title: Bryan Danielson

text: In response to fans on Twitter mistaking a part of his skin for a nicotine patch in 2011, Danielson clarified that he does not smoke and that the skin discoloration stems from his vitiligo. He is a fan of the Seattle Seahawks American football team and was given control of the team's Twitter account for a Q&A session in 2015, as well as wearing Seahawks-themed wrestling gear at SummerSlam in 2018. He also supports English football team Everton FC. A self-described environmentalist and anti-consumerist, he has discussed feeling like a hypocrite for selling WWE merchandise, and endorsed Green Party nominee Jill Stein in the 2016 presidential election.


title: Lewis and Clark Expedition

text: The Lewis and Clark Expedition, also known as the Corps of Discovery Expedition, was the United States expedition to cross the newly acquired western portion of the country after the Louisiana Purchase. The Corps of Discovery was a select group of U.S. Army and civilian volunteers under the command of Captain Meriwether Lewis and his close friend Second Lieutenant William Clark. Clark and 30 members set out from Camp Dubois, Illinois, on May 14, 1804, met Lewis and ten other members of the group in St. Charles, Missouri, then went up the Missouri River. The expedition crossed the Continental Divide of the Americas near the Lemhi Pass, eventually coming to the Columbia River, and the Pacific Ocean in 1805. The return voyage began on March 23, 1806, at Fort Clatsop, Oregon, and ended on September 23 of the same year.


title: Lewis and Clark Expedition

text: President Thomas Jefferson commissioned the expedition shortly after the Louisiana Purchase in 1803 to explore and to map the newly acquired territory, to find a practical route across the western half of the continent, and to establish an American presence in this territory before European powers attempted to establish claims in the region. The campaign's secondary objectives were scientific and economic: to study the area's plants, animal life, and geography, and to establish trade with local Native American tribes. The expedition returned to St. Louis to report its findings to Jefferson, with maps, sketches, and journals in hand.


title: Lewis and Clark Expedition

text: One of Thomas Jefferson's goals was to find "the most direct and practicable water communication across this continent, for the purposes of commerce." He also placed special importance on declaring US sovereignty over the land occupied by the many different Native American tribes along the Missouri River, and getting an accurate sense of the resources in the recently completed Louisiana Purchase. The expedition made notable contributions to science, but scientific research was not the main goal of the mission.


title: Lewis and Clark Expedition

text: During the 19th century, references to Lewis and Clark "scarcely appeared" in history books, even during the United States Centennial in 1876, and the expedition was largely forgotten. Lewis and Clark began to gain attention around the start of the 20th century. Both the 1904 Louisiana Purchase Exposition in St. Louis and the 1905 Lewis and Clark Centennial Exposition in Portland, Oregon, showcased them as American pioneers. However, the story remained relatively shallow until mid-century as a celebration of US conquest and personal adventures, but more recently the expedition has been more thoroughly researched.


title: Lewis and Clark Expedition

text: As of 1984, no US exploration party was more famous, and no American expedition leaders are more recognizable by name.


title: Lewis and Clark Expedition

text: In 2004, a complete and reliable set of the expedition's journals was compiled by Gary E. Moulton. Circa 2004, the bicentennial of the expedition further elevated popular interest in Lewis and Clark.


title: Lewis and Clark Expedition

text: The timeline covers the primary events associated with the expedition, from January 1803 through January 1807.


title: Lewis and Clark Expedition

text: For years, Thomas Jefferson read accounts about the ventures of various explorers in the western frontier, and consequently had a long-held interest in further exploring this mostly unknown region of the continent. In the 1780s, while Minister to France, Jefferson met John Ledyard in Paris and they discussed a possible trip to the Pacific Northwest. Jefferson had also read Captain James Cook's "A Voyage to the Pacific Ocean" (London, 1784), an account of Cook's third voyage, and Le Page du Pratz's "The History of Louisiana" (London, 1763), all of which greatly influenced his decision to send an expedition. Like Captain Cook, he wished to discover a practical route through the Northwest to the Pacific coast. Alexander Mackenzie had already charted a route in his quest for the Pacific, following Canada's Mackenzie River to the Arctic Ocean in 1789. Mackenzie and his party were the first to cross America north of Mexico, reaching the Pacific coast in British Columbia in 1793–a dozen years before Lewis and Clark. Mackenzie's accounts in "Voyages from Montreal" (1801) informed Jefferson of Britain's intent to establish control over the lucrative fur trade of the Columbia River and convinced him of the importance of securing the territory as soon as possible. At Philadelphia, Israel Whelan, the purveyor of public supplies, purchased supplies for the expedition after a list provided by Lewis. Among the purchased items were found 193 pounds of portable soup, 130 rolls of pigtail tobacco, 30 gallons of strong spirit of wine, a wide assortment of Native American presents,


title: Lewis and Clark Expedition

text: Two years into his presidency, Jefferson asked Congress to fund an expedition through the Louisiana territory to the Pacific Ocean. He did not attempt to make a secret of the Lewis and Clark expedition from Spanish, French, and British officials, but rather claimed different reasons for the venture. He used a secret message to ask for funding due to poor relations with the opposition Federalist Party in Congress. Congress subsequently appropriated $2,324 for supplies and food, the appropriation of which was left in Lewis's charge.


title: Lewis and Clark Expedition

text: In 1803, Jefferson commissioned the Corps of Discovery and named Army Captain Meriwether Lewis its leader, who then invited William Clark to co-lead the expedition with him. Lewis demonstrated remarkable skills and potential as a frontiersman, and Jefferson made efforts to prepare him for the long journey ahead as the expedition was gaining approval and funding. Jefferson explained his choice of Lewis:


title: Lewis and Clark Expedition

text: It was impossible to find a character who to a complete science in botany, natural history, mineralogy & astronomy, joined the firmness of constitution & character, prudence, habits adapted to the woods & a familiarity with the Indian manners and character, requisite for this undertaking. All the latter qualifications Capt. Lewis has.


title: Lewis and Clark Expedition

text: In 1803, Jefferson sent Lewis to Philadelphia to study medicinal cures under Benjamin Rush, a physician and humanitarian. He also arranged for Lewis to be further educated by Andrew Ellicott, an astronomer who instructed him in the use of the sextant and other navigational instruments. From Benjamin Smith Barton, Lewis learned how to describe and preserve plant and animal specimens, from Robert Patterson refinements in computing latitude and longitude, while Caspar Wistar covered fossils, and the search for possible living remnants. Lewis, however, was not ignorant of science and had demonstrated a marked capacity to learn, especially with Jefferson as his teacher. At Monticello, Jefferson possessed an enormous library on the subject of the geography of the North American continent, and Lewis had full access to it. He spent time consulting maps and books and conferring with Jefferson.


title: Lewis and Clark Expedition

text: The keelboat used for the first year of the journey was built near Pittsburgh, Pennsylvania, in the summer of 1803 at Lewis's specifications. The boat was completed on August 31 and was immediately loaded with equipment and provisions. While in Pittsburgh, Lewis bought a Newfoundland dog, Seaman, to accompany them. Newfoundlands are working dogs and good swimmers; commonly found on fishing boats, they can assist in water rescues. Seaman proved a valuable member of the party, helping with hunting and protection from bears and other wildlife. He was the only animal to complete the entire trip.


title: Lewis and Clark Expedition

text: Lewis and his crew set sail that afternoon, traveling down the Ohio River to meet up with Clark near Louisville, Kentucky in October 1803 at the Falls of the Ohio. Their goals were to explore the vast territory acquired by the Louisiana Purchase and to establish trade and US sovereignty over the Native Americans along the Missouri River. Jefferson also wanted to establish a US claim of "discovery" to the Pacific Northwest and Oregon territory by documenting an American presence there before European nations could claim the land. According to some historians, Jefferson understood that he would have a better claim of ownership to the Pacific Northwest if the team gathered scientific data on animals and plants. However, his main objectives were centered around finding an all-water route to the Pacific coast and commerce. His instructions to the expedition stated:


title: Lewis and Clark Expedition

text: The US mint prepared special silver medals with a portrait of Jefferson and inscribed with a message of friendship and peace, called Indian Peace Medals. The soldiers were to distribute them to the tribes that they met. The expedition also prepared advanced weapons to display their military firepower. Among these was an Austrian-made .46 caliber Girandoni air rifle, a repeating rifle with a 20-round tubular magazine that was powerful enough to kill a deer. The expedition was prepared with flintlock firearms, knives, blacksmithing supplies, and cartography equipment. They also carried flags, gift bundles, medicine, and other items that they would need for their journey.


title: Lewis and Clark Expedition

text: The route of Lewis and Clark's expedition took them up the Missouri River to its headwaters, then on to the Pacific Ocean via the Columbia River, and it may have been influenced by the purported transcontinental journey of Moncacht-Apé by the same route about a century before. Jefferson had a copy of Le Page's book in his library detailing Moncacht-Apé's itinerary, and Lewis carried a copy with him during the expedition. Le Page's description of Moncacht-Apé's route across the continent neglects to mention the need to cross the Rocky Mountains, and it might be the source of Lewis and Clark's mistaken belief that they could easily carry boats from the Missouri's headwaters to the westward-flowing Columbia.


title: Lewis and Clark Expedition

text: The Corps of Discovery departed from Camp Dubois (Camp Wood) at 4pm on May 14, 1804. Under Clark's command, they traveled up the Missouri River in their keelboat and two pirogues to St. Charles, Missouri where Lewis joined them six days later. The expedition set out the next afternoon, May 21. While accounts vary, it is believed the Corps had as many as 45 members, including the officers, enlisted military personnel, civilian volunteers, and Clark's African-American slave York.


title: Lewis and Clark Expedition

text: From St. Charles, the expedition followed the Missouri through what is now Kansas City, Missouri, and Omaha, Nebraska. On August 20, 1804, Sergeant Charles Floyd died, apparently from acute appendicitis. He had been among the first to sign up with the Corps of Discovery and was the only member to die during the expedition. He was buried at a bluff by the river, now named after him, in what is now Sioux City, Iowa. His burial site was marked with a cedar post on which was inscribed his name and day of death. up the river, the expedition camped at a small river which they named Floyd's River. During the final week of August, Lewis and Clark reached the edge of the Great Plains, a place abounding with elk, deer, bison, and beavers.


title: Lewis and Clark Expedition

text: The Lewis and Clark Expedition established relations with two dozen Native American nations, without whose help the expedition would have risked starvation during the harsh winters or become hopelessly lost in the vast ranges of the Rocky Mountains.


title: Lewis and Clark Expedition

text: The Americans and the Lakota nation (whom the Americans called Sioux or "Teton-wan Sioux") had problems when they met, and there was a concern the two sides might fight. According to Harry W. Fritz, "All earlier Missouri River travelers had warned of this powerful and aggressive tribe, determined to block free trade on the river. ... The Sioux were also expecting a retaliatory raid from the Omaha tribe, to the south. A recent Sioux raid had killed 75 Omaha men, burned 40 lodges, and taken four dozen prisoners." The expedition held talks with the Lakota near the confluence of the Missouri and Bad Rivers in what is now Fort Pierre, South Dakota.


title: Lewis and Clark Expedition

text: One of their horses disappeared, and they believed the Sioux were responsible. Afterward, the two sides met and there was a disagreement, and the Sioux asked the men to stay or to give more gifts instead before being allowed to pass through their territory. They came close to fighting several times, and both sides finally backed down and the expedition continued on to Arikara territory. Clark wrote they were "warlike" and were the "vilest miscreants of the savage race".


title: Lewis and Clark Expedition

text: In the winter of 180405, the party built Fort Mandan, near present-day Washburn, North Dakota. Just before departing on April 7, 1805, the expedition sent the keelboat back to St. Louis with a sample of specimens, some never seen before east of the Mississippi. One chief asked Lewis and Clark to provide a boat for passage through their national territory. As tensions increased, Lewis and Clark prepared to fight, but the two sides fell back in the end. The Americans quickly continued westward (upriver), and camped for the winter in the Mandan nation's territory.


title: Lewis and Clark Expedition

text: After the expedition had set up camp, nearby Native Americans came to visit in fair numbers, some staying all night. For several days, Lewis and Clark met in council with Mandan chiefs. Here they met a French-Canadian fur trapper named Toussaint Charbonneau, and his young Shoshone wife Sacagawea. Charbonneau at this time began to serve as the expedition's translator. Peace was established between the expedition and the Mandan chiefs with the sharing of a Mandan ceremonial pipe. By April 25, Captain Lewis wrote his progress report of the expedition's activities and observations of the Native American nations they have encountered to date: "A Statistical view of the Indian nations inhabiting the Territory of Louisiana", which outlined the names of various tribes, their locations, trading practices, and water routes used, among other things. President Jefferson would later present this report to Congress.


title: Lewis and Clark Expedition

text: They followed the Missouri to its headwaters, and over the Continental Divide at Lemhi Pass. In canoes, they descended the mountains by the Clearwater River, the Snake River, and the Columbia River, past Celilo Falls, and past what is now Portland, Oregon, at the meeting of the Willamette and Columbia Rivers. Lewis and Clark used William Robert Broughton's 1792 notes and maps to orient themselves once they reached the lower Columbia River. The sighting of Mount Hood and other stratovolcanos confirmed that the expedition had almost reached the Pacific Ocean.


title: Lewis and Clark Expedition

text: The expedition sighted the Pacific Ocean for the first time on November 7, 1805, arriving two weeks later. The expedition faced its second bitter winter camped on the north side of the Columbia River, in a storm-wracked area. Lack of food was a major factor. The elk, the party's main source of food, had retreated from their usual haunts into the mountains, and the party was now too poor to purchase enough food from neighboring tribes. On November 24, 1805, the party voted to move their camp to the south side of the Columbia River near modern Astoria, Oregon. Sacagawea, and Clark's slave York, were both allowed to participate in the vote.


title: Lewis and Clark Expedition

text: On the south side of the Columbia River, upstream on the west side of the Netul River (now Lewis and Clark River), they constructed Fort Clatsop. They did this not just for shelter and protection, but also to officially establish the American presence there, with the American flag flying over the fort. During the winter at Fort Clatsop, Lewis committed himself to writing. He filled many pages of his journals with valuable knowledge, mostly about botany, because of the abundant growth and forests that covered that part of the continent. The health of the men also became a problem, with many suffering from colds and influenza.


title: Lewis and Clark Expedition

text: Knowing that maritime fur traders sometimes visited the lower Columbia River, Lewis and Clark repeatedly asked the local Chinooks about trading ships. They learned that Captain Samuel Hill had been there in early 1805. Miscommunication caused Clark to record the name as "Haley". Captain Hill returned in November 1805, and anchored about from Fort Clatsop. The Chinook told Hill about Lewis and Clark, but no direct contact was made.


title: Lewis and Clark Expedition

text: Lewis was determined to remain at the fort until April 1, but was still anxious to move out at the earliest opportunity. By March 22, the stormy weather had subsided and the following morning, on March 23, 1806, the journey home began. The Corps began their journey homeward using canoes to ascend the Columbia River, and later by trekking over land.


title: Lewis and Clark Expedition

text: Before leaving, Clark gave the Chinook a letter to give to the next ship captain to visit, which was the same Captain Hill who had been nearby during the winter. Hill took the letter to Canton and had it forwarded to Thomas Jefferson, who thus received it before Lewis and Clark returned.


title: Lewis and Clark Expedition

text: They made their way to Camp Chopunnish in Idaho, along the north bank of the Clearwater River, where the members of the expedition collected 65 horses in preparation to cross the Bitterroot Mountains, lying between modern-day Idaho and western Montana. However, the range was still covered in snow, which prevented the expedition from making the crossing. On April 11, while the Corps was waiting for the snow to diminish, Lewis's dog, Seaman, was stolen by Native Americans, but was retrieved shortly. Worried that other such acts might follow, Lewis warned the chief that any other wrongdoing or mischievous acts would result in instant death.


title: Lewis and Clark Expedition

text: On July 3, before crossing the Continental Divide, the Corps split into two teams so Lewis could explore the Marias River. Lewis's group of four met some men from the Blackfeet nation. During the night, the Blackfeet tried to steal their weapons. In the struggle, the soldiers killed two Blackfeet men. Lewis, George Drouillard, and the Field brothers fled over in a day before they camped again.


title: Lewis and Clark Expedition

text: Meanwhile, Clark had entered the Crow tribe's territory. In the night, half of Clark's horses disappeared, but not a single Crow had been seen. Lewis and Clark stayed separated until they reached the confluence of the Yellowstone and Missouri Rivers on August 11. As the groups reunited, one of Clark's hunters, Pierre Cruzatte, mistook Lewis for an elk and fired, injuring Lewis in the thigh. Once together, the Corps was able to return home quickly via the Missouri River. They reached St. Louis on September 23, 1806.


title: Lewis and Clark Expedition

text: In March 1804, before the expedition began in May, the Spanish in New Mexico learned from General James Wilkinson that the Americans were encroaching on territory claimed by Spain. After the Lewis and Clark expedition set off in May, the Spanish sent four armed expeditions of 52 soldiers, mercenaries , and Native Americans on August 1, 1804, from Santa Fe, New Mexico northward under Pedro Vial and José Jarvet to intercept Lewis and Clark and imprison the entire expedition. They reached the Pawnee settlement on the Platte River in central Nebraska and learned that the expedition had been there many days before. The expedition was covering a day and Vial's attempt to intercept them was unsuccessful.


title: Lewis and Clark Expedition

text: The Lewis and Clark Expedition gained an understanding of the geography of the Northwest and produced the first accurate maps of the area. During the journey, Lewis and Clark drew about 140 maps. Stephen Ambrose says the expedition "filled in the main outlines" of the area.


title: Lewis and Clark Expedition

text: The expedition documented natural resources and plants that had been previously unknown to Euro-Americans, though not to the indigenous peoples. Lewis and Clark were the first Americans to cross the Continental Divide, and the first Americans to see Yellowstone, enter into Montana, and produce an official description of these different regions. Their visit to the Pacific Northwest, maps, and proclamations of sovereignty with medals and flags were legal steps needed to claim title to each indigenous nation's lands under the Doctrine of Discovery.


title: Lewis and Clark Expedition

text: The expedition was sponsored by the American Philosophical Society (APS). Lewis and Clark received some instruction in astronomy, botany, climatology, ethnology, geography, meteorology, mineralogy, ornithology, and zoology. During the expedition, they made contact with over 70 Native American tribes and described more than 200 new plant and animal species.


title: Lewis and Clark Expedition

text: Jefferson had the expedition declare "sovereignty" and demonstrate their military strength to ensure native tribes would be subordinate to the U.S., as European colonizers did elsewhere. After the expedition, the maps that were produced allowed the further discovery and settlement of this vast territory in the years that followed.


title: Lewis and Clark Expedition

text: In 1807, Patrick Gass, a private in the U.S. Army, published an account of the journey. He was promoted to sergeant during the course of the expedition. Paul Allen edited a two-volume history of the Lewis and Clark expedition that was published in 1814, in Philadelphia, but without mention of the actual author, banker Nicholas Biddle. Even then, the complete report was not made public until more recently. The earliest authorized edition of the Lewis and Clark journals resides in the Maureen and Mike Mansfield Library at the University of Montana.


title: Lewis and Clark Expedition

text: One of the expedition's primary objectives as directed by President Jefferson was to be a surveillance mission that would report back the whereabouts, military strength, lives, activities, and cultures of the various Native American tribes that inhabited the territory newly acquired by the United States as part of the Louisiana Purchase and the northwest in general. The expedition was to make native people understand that their lands now belonged to the United States and that "their great father" in Washington was now their sovereign. The expedition encountered many different native nations and tribes along the way, many of whom offered their assistance, providing the expedition with their knowledge of the wilderness and with the acquisition of food. The expedition had blank leather-bound journals and ink for the purpose of recording such encounters, as well as for scientific and geological information. They were also provided with various gifts of medals, ribbons, needles, mirrors, and other articles which were intended to ease any tensions when negotiating their passage with the various Native American chiefs whom they would encounter along their way.


title: Lewis and Clark Expedition

text: Many of the tribes had friendly experiences with British and French fur traders in various isolated encounters along the Missouri and Columbia Rivers, and for the most part the expedition did not encounter hostilities. However, there was a tense confrontation on September 25, 1804, with the Teton-Sioux tribe (also known as the Lakota people, one of the three tribes that comprise the Great Sioux Nation), under chiefs that included Black Buffalo and the Partisan. These chiefs confronted the expedition and demanded tribute from the expedition for their passage over the river. The seven native tribes that comprised the Lakota people controlled a vast inland empire and expected gifts from strangers who wished to navigate their rivers or to pass through their lands. According to Harry W. Fritz, "All earlier Missouri River travelers had warned of this powerful and aggressive tribe, determined to block free trade on the river. ... The Sioux were also expecting a retaliatory raid from the Omaha tribe, to the south. A recent Sioux raid had killed 75 Omaha men, burned 40 lodges, and taken four dozen prisoners."


title: Lewis and Clark Expedition

text: Captain Lewis made his first mistake by offering the Sioux chief gifts first, which insulted and angered the Partisan chief. Communication was difficult, since the expedition's only Sioux language interpreter was Pierre Dorion who had stayed behind with the other party and was also involved with diplomatic affairs with another tribe. Consequently, both chiefs were offered a few gifts, but neither was satisfied and they wanted some gifts for their warriors and tribe. At that point, some of the warriors from the Partisan tribe took hold of their boat and one of the oars. Lewis took a firm stand, ordering a display of force and presenting arms; Captain Clark brandished his sword and threatened violent reprisal. Just before the situation erupted into a violent confrontation, Black Buffalo ordered his warriors to back off.


title: Lewis and Clark Expedition

text: The captains were able to negotiate their passage without further incident with the aid of better gifts and a bottle of whiskey. During the next two days, the expedition made camp not far from Black Buffalo's tribe. Similar incidents occurred when they tried to leave, but trouble was averted with gifts of tobacco.


title: Lewis and Clark Expedition

text: As the expedition encountered the various Native American tribes during the course of their journey, they observed and recorded information regarding their lifestyles, customs and the social codes they lived by, as directed by President Jefferson. By European standards, the Native American way of life seemed harsh and unforgiving as witnessed by members of the expedition. After many encounters and camping in close proximity to the Native American nations for extended periods of time during the winter months, they soon learned first hand of their customs and social orders.


title: Lewis and Clark Expedition

text: One of the primary customs that distinguished Native American cultures from those of the West was that it was customary for the men to take on two or more wives if they were able to provide for them and often took on a wife or wives who were members of the immediate family circle, e.g. men in the Minnetaree and Mandan tribes would often take on a sister for a wife. Chastity among women was not held in high regard. Infant daughters were often sold by the father to men who were grown, usually for horses or mules.


title: Lewis and Clark Expedition

text: They learned that women in Sioux nations were often bartered away for horses or other supplies, yet this was not practiced among the Shoshone nation who held their women in higher regard. They witnessed that many of the Native American nations were constantly at war with other tribes, especially the Sioux, who, while remaining generally friendly to the white fur traders, had proudly boasted of and justified the almost complete destruction of the once great Cahokia nation, along with the Missouris, Illinois, Kaskaskia, and Piorias tribes that lived about the countryside adjacent to the upper Mississippi and Missouri rivers.


title: Lewis and Clark Expedition

text: Sacagawea, sometimes spelled Sakajawea or Sakagawea ( 1788December 20, 1812), was a Shoshone Native American woman who arrived with her husband and owner Toussaint Charbonneau on the expedition to the Pacific Ocean.


title: Lewis and Clark Expedition

text: On February 11, 1805, a few weeks after her first contact with the expedition, Sacagawea went into labor which was slow and painful, so the Frenchman Charbonneau suggested she be given a potion of rattlesnake's rattle to aid in her delivery. Lewis happened to have some snake's rattle with him. A short time after administering the potion, she delivered a healthy boy who was given the name Jean Baptiste Charbonneau.


title: Lewis and Clark Expedition

text: When the expedition reached Marias River, on June 16, 1805, Sacagawea became dangerously ill. She was able to find some relief by drinking mineral water from the sulphur spring that fed into the river.


title: Lewis and Clark Expedition

text: Though she has been discussed in literature frequently, much of the information is exaggeration or fiction. Scholars say she did notice some geographical features, but "Sacagawea ... was not the guide for the Expedition, she was important to them as an interpreter and in other ways." The sight of a woman and her infant son would have been reassuring to some indigenous nations, and she played an important role in diplomatic relations by talking to chiefs, easing tensions, and giving the impression of a peaceful mission.


title: Lewis and Clark Expedition

text: In his writings, Meriwether Lewis presented a somewhat negative view of her, though Clark had a higher regard for her, and provided some support for her children in subsequent years. In the journals, they used the terms "squar" (squaw) and "savages" to refer to Sacagawea and other indigenous peoples.


title: Lewis and Clark Expedition

text: An enslaved black man known only as York took part in the expedition as personal servant to William Clark, his owner. York did much to help the expedition succeed. He proved popular with the Native Americans, who had never seen a black man. He also helped with hunting and the heavy labor of pulling boats upstream. Expecting his freedom after the expedition, he was disappointed when Clark refused repeatedly. While all the other explorers enjoyed rewards of double pay and land, York received nothing. Clark would not allow York to remain in Louisville with his wife and probably children. He whipped York and put him in jail. The last years of York's life are disputed. In the 1830s, a black man who said he had first come with Lewis and Clark was living as a chief with Native Americans they met on the expedition, in modern Wyoming.


title: Lewis and Clark Expedition

text: The Corps met their objective of reaching the Pacific, mapping and establishing their presence for a legal claim to the land. They established diplomatic relations and trade with at least two dozen indigenous nations. They did not find a continuous waterway to the Pacific Ocean but located a Native American trail that led from the upper end of the Missouri River to the Columbia River which ran to the Pacific Ocean. They gained information about the natural habitat, flora and fauna, bringing back various plant, seed and mineral specimens. They mapped the topography of the land, designating the location of mountain ranges, rivers and the many Native American tribes during the course of their journey. They also learned and recorded much about the language and customs of the Native American tribes they encountered, and brought back many of their artifacts, including bows, clothing and ceremonial robes.


title: Lewis and Clark Expedition

text: Two months passed after the expedition's end before Jefferson made his first public statement to Congress and others, giving a one-sentence summary about the success of the expedition before getting into the justification for the expenses involved. In the course of their journey, they acquired a knowledge of numerous tribes of Native Americans hitherto unknown; they informed themselves of the trade which may be carried on with them, the best channels and positions for it, and they are enabled to give with accuracy the geography of the line they pursued. Back east, the botanical and zoological discoveries drew the intense interest of the American Philosophical Society who requested specimens, various artifacts traded with the Native Americans, and reports on plants and wildlife along with various seeds obtained. Jefferson used seeds from "Missouri hominy corn" along with a number of other unidentified seeds to plant at Monticello which he cultivated and studied. He later reported on the "Indian corn" he had grown as being an "excellent" food source. The expedition helped establish the U.S. presence in the newly acquired territory and beyond and opened the door to further exploration, trade and scientific discoveries.


title: Lewis and Clark Expedition

text: Lewis and Clark returned from their expedition, bringing with them the Mandan Native American Chief Shehaka from the Upper Missouri to visit the "Great Father" in Washington. After Chief Shehaka's visit, it required multiple attempts and multiple military expeditions to safely return Shehaka to his nation.


title: Lewis and Clark Expedition

text: In the 1970s, the federal government memorialized the winter assembly encampment, Camp Dubois, as the start of the Lewis and Clark voyage of discovery and in 2019 it recognized Pittsburgh, Pennsylvania as the start of the expedition.


title: Lewis and Clark Expedition

text: Since the expedition, Lewis and Clark have been commemorated and honored over the years on various coins, currency, and commemorative postage stamps, as well as in a number of other capacities. In 2004, the American elm cultivar "Ulmus americana" 'Lewis & Clark' (selling name ) was released by North Dakota State University Research Foundation in commemoration of the expedition's bicentenary; the tree has a resistance to Dutch elm disease.


title: Lewis and Clark Expedition

text: In 1682, René-Robert Cavelier, Sieur de La Salle traveled down the Mississippi from the Great Lakes to the Gulf. The French then established a chain of posts along the Mississippi from New Orleans to the Great Lakes. There followed a number of French explorers including Pedro Vial and Pierre Antoine and Paul Mallet, among others. Vial may have preceded Lewis and Clark to Montana. In 1787, he gave a map of the upper Missouri River and locations of "territories transited by Pedro Vial" to Spanish authorities.


title: Lewis and Clark Expedition

text: Early in 1792, the American explorer Robert Gray, sailing in the "Columbia Rediviva", discovered the yet to be named Columbia River, named it after his ship and claimed it for the United States. Later in 1792, the Vancouver Expedition had learned of Gray's discovery and used his maps. Vancouver's expedition explored over up the Columbia, into the Columbia River Gorge. Lewis and Clark used the maps produced by these expeditions when they descended the lower Columbia to the Pacific coast.


title: Nora Ephron

text: Nora Ephron ( ; May 19, 1941 – June 26, 2012) was an American journalist, writer, and filmmaker. She is best known for her romantic comedy films and was nominated three times for the Writers Guild of America Award and the Academy Award for Best Original Screenplay for "Silkwood" (1983), "When Harry Met Sally..." (1989), and "Sleepless in Seattle" (1993). She won the BAFTA Award for Best Original Screenplay for "When Harry Met Sally...", which the Writers Guild of America ranked as the 40th greatest screenplay of all time.


title: Nora Ephron

text: Ephron's first produced play, "Imaginary Friends" (2002), was honored as one of the ten best plays of the 2002–03 New York theatre season. She also co-authored the Drama Desk Award–winning theatrical production "Love, Loss, and What I Wore". In 2013, Ephron received a posthumous Tony Award nomination for Best Play for "Lucky Guy".


title: Nora Ephron

text: Ephron also directed films, usually from her own screenplays, including "Sleepless in Seattle" (1993) and "You've Got Mail" (1998), both starring Meg Ryan and Tom Hanks.


title: Nora Ephron

text: Ephron was born in New York City on May 19, 1941, to a Jewish family. She was the eldest of four daughters, and grew up in Beverly Hills, California. Her parents, Phoebe (née Wolkind) and Henry Ephron, were both East Coast-born and were noted playwrights and screenwriters. Her parents named her Nora after the protagonist in the play "A Doll's House" by Henrik Ibsen. Nora's younger sisters, Delia and Amy, are also screenwriters. Her sister Hallie Ephron is a journalist, book reviewer, and novelist who writes crime fiction. Ephron's parents based the ingenue character in the play and film version of "Take Her, She's Mine" on the 22-year-old Nora and her letters from college; Sandra Dee played the character based on Nora in the film version, with James Stewart portraying her father. Both her parents became alcoholics during their declining years.


title: Nora Ephron

text: As a high school student, Ephron dreamed of going to New York City to become another Dorothy Parker, an American poet, writer, satirist, and critic. Ephron has cited her high school journalism teacher, Charles Simms, as the inspiration for her pursuit of a career in journalism. She graduated from Beverly Hills High School in 1958, and from Wellesley College in Massachusetts, in 1962 with a degree in political science.


title: Nora Ephron

text: After graduating from Wellesley College in 1962, Ephron worked briefly as an intern in the White House of President John F. Kennedy. She also applied to be a writer at "Newsweek". After she was told they did not hire women writers, she accepted a position as a mail girl.


title: Nora Ephron

text: After eventually quitting "Newsweek" because she was not allowed to write, Ephron participated in a class action lawsuit against the magazine for sexual discrimination, described in the book "The Good Girls Revolt: How the Women of Newsweek Sued Their Bosses and Changed the Workplace" by Lynn Povich, and both the lawsuit and Ephron's role were fictionalized in a 2016 Amazon series by the similar main title "Good Girls Revolt".


title: Nora Ephron

text: After a satire in "Monocle" she wrote lampooning the "New York Post" caught the editor's eye, Ephron accepted a job at the "Post", where she worked as a reporter for five years. In 1966, she broke the news in the "Post" that Bob Dylan had married Sara Lownds in a private ceremony. Upon becoming a successful writer, she wrote a column on women's issues for "Esquire". In this position, Ephron made a name for herself by writing "A Few Words About Breasts," a humorous essay about body image that "established her as the enfant terrible of the New Journalism." While at "Esquire", she took on subjects as wide-ranging as Dorothy Schiff, her former boss and owner of the "Post"; Betty Friedan, whom she chastised for pursuing a feud with Gloria Steinem; and her alma mater Wellesley, which she said had turned out "a generation of docile and unadventurous women." A 1968 send-up of "Women's Wear Daily" that she wrote for "Cosmopolitan" resulted in threats of a lawsuit from "WWD."


title: Nora Ephron

text: Ephron rewrote a script for "All the President's Men" in the mid-1970s, along with her then husband, investigative journalist Carl Bernstein. While the script was not used, it was seen by someone who offered Ephron her first screenwriting job, for a television movie, which began her screenwriting career.


title: Nora Ephron

text: In 1983, Ephron coscripted the film "Silkwood" with Alice Arlen. The film, directed by Mike Nichols, stars Meryl Streep as Karen Silkwood, a whistleblower at the Kerr McGee Cimarron nuclear facility who dies under suspicious circumstances. Ephron and Arlen were nominated for the Best Original Screenplay Oscar in 1984 for "Silkwood."


title: Nora Ephron

text: Ephron's novel "Heartburn" was published in 1983. The novel is a semi-autobiographical account of her marriage with Carl Bernstein. The film adaptation was released in 1986, directed by Mike Nichols starring Meryl Streep and Jack Nicholson. Ephron adapted her own novel into the screenplay for the film. In the film, Ephron's fictionalized portrayal of herself, played by Streep, is a pregnant food writer when she learns about her husband's affair.


title: Nora Ephron

text: Ephron wrote the script for the romantic comedy "When Harry Met Sally..." in 1986. The film, released in 1989, was directed by Rob Reiner, starred Billy Crystal and Meg Ryan. The film depicts the decade-long relationship between Harry (Crystal) and Sally (Ryan) as they navigate their own romantic relationships. Ephron has claimed that she wrote this screenplay with Reiner in mind as the character of Harry, and herself as the character of Sally. The film has become iconic in the romantic comedy genre, most notably for the scene in which Sally pretends to have an orgasm in the middle of Katz's Deli during lunch. Ephron said she wrote the part of Sally simulating an orgasm into the script per Meg Ryan's suggestions. Additionally, the comment "I'll have what she's having" said by a deli patron (played by Rob Reiner's real-life mother Estelle Reiner) watching the scene unfold nearby, was an idea from Billy Crystal. Ephron's script was nominated for the 1990 Oscar in Best Writing, Screenplay Written Directly for the Screen.


title: Nora Ephron

text: Ephron's directorial debut was the 1992 film "This Is My Life." Ephron and her sister Delia Ephron wrote the script based on Meg Wolitzer's novel "This is Your Life." The film is about a woman who decides to pursue a career in stand-up comedy after inheriting a substantial sum of money from a relative. In a conversation released by Criterion Channel between Lena Dunham, and Ephron, she stated "That movie I made completely for Woody Allen." She later stated in the conversation that he saw it and liked it.


title: Nora Ephron

text: In 1993, Ephron directed and wrote the script for the romantic comedy "Sleepless in Seattle". The film stars Tom Hanks as Sam Baldwin, a recently widowed father whose son calls into a Chicago-based radio talk show in an attempt to find his father a new partner. After hearing this call, Baltimore resident Annie Reed, played by Meg Ryan, becomes infatuated with Sam, and sets up a rendezvous for the two to meet in New York City.


title: Nora Ephron

text: In 1998, Ephron released the film "You've Got Mail", which she wrote the script for, with her sister Delia Ephron, and directed. The story is a loose adaptation of the Ernst Lubitsch film from 1940 "The Shop Around the Corner." "You've Got Mail" stars Meg Ryan as Kathleen Kelly, an owner of a small, independent children's bookstore in New York City. Her quiet life is then threatened by Fox Books, a Barnes & Noble-esque book selling chain, which opens near her shop. Fox Books is run by Joe Fox, played by Tom Hanks. Joe and Kathleen navigate a tumultuous business rivalry, while unknowingly forming an intimate connection with each other via email.


title: Nora Ephron

text: In 2007, Ephron received the Golden Plate Award of the American Academy of Achievement presented by Awards Council member George Lucas.


title: Nora Ephron

text: In 2009, Ephron directed and co-wrote the screenplay for "Julie & Julia". The film is based on Julie Powell's blog and memoir of the same title. The film is about Julia Child, the famous American chef played by Meryl Streep, and Julie Powell, a New Yorker attempting to cook her way through Child's cookbook, played by Amy Adams. As Powell blogs her experience, the film flashes back to the story of Child's first stages of her career as she trains in a French culinary school. The film was a commercial success.


title: Nora Ephron

text: Ephron's 2002 play "Imaginary Friends" explores the rivalry between writers Lillian Hellman and Mary McCarthy. She co-authored the play "Love, Loss, and What I Wore" (based on the book by Ilene Beckerman) with her sister Delia, and it has played to sold-out audiences in Canada, New York City and Los Angeles.


title: Nora Ephron

text: Ephron was married three times. Her first marriage, to writer Dan Greenburg, ended in divorce after nine years. In 1976, she married journalist Carl Bernstein. In 1979, Ephron had a toddler son, Jacob, and was pregnant with her second son Max when she discovered Bernstein's affair with their mutual friend, married British journalist Margaret Jay, daughter of former British prime minister James Callaghan. Ephron was inspired by this to write the 1983 novel "Heartburn", which was then made into a 1986 Mike Nichols film starring Jack Nicholson and Meryl Streep. In the book, Ephron wrote of a husband named Mark, who was "capable of having sex with a Venetian blind." She also wrote that the character Thelma (based on Margaret Jay) looked like a giraffe with "big feet". Bernstein threatened to sue over the book and film, but never did.


title: Nora Ephron

text: Ephron was married for more than 20 years to screenwriter Nicholas Pileggi, from 1987 until her death in 2012. The couple lived in the Hollywood Hills in Los Angeles, and in New York City.


title: Nora Ephron

text: Ephron's friend Richard Cohen said of her, "She was very Jewish, culturally and emotionally. She identified fully as a Jewish woman." However, Ephron was not religious. "You can never have too much butter – that is my belief. If I have a religion, that's it", she quipped in an NPR interview about her 2009 movie "Julie & Julia".


title: Nora Ephron

text: Ephron's son, Jacob Bernstein, directed an HBO movie on her life titled "Everything Is Copy". As of 2021, he is a reporter for "The New York Times".


title: Nora Ephron

text: For many years, Ephron was one of the very few people who knew the identity of Deep Throat, the anonymous informer for articles written by her ex-husband Carl Bernstein and Bob Woodward uncovering the Watergate scandal. Ephron read Bernstein's notes, which referred to Deep Throat as "MF"; Bernstein said it stood for "My Friend," but Ephron correctly guessed it stood for Mark Felt, the former associate director of the FBI.


title: Nora Ephron

text: After Ephron's marriage with Bernstein ended, Ephron revealed Deep Throat's identity to her son Jacob and anyone else who asked. She once said, "I would give speeches to 500 people and someone would say, 'Do you know who Deep Throat is?' And I would say, 'It's Mark Felt.'" Classmates of Jacob Bernstein at the Dalton School and Vassar College recall Jacob's revealing to numerous people that Felt was Deep Throat. This revelation attracted little media attention during the many years that the identity of Deep Throat was a mystery. Ephron said, "No one, apart from my sons, believed me." Ephron was invited by Arianna Huffington to write about the experience in "The Huffington Post", for which she was a regular blogger and part-time editor.


title: Nora Ephron

text: In 2006, Ephron was diagnosed with myelodysplasia. She chose not to disclose her diagnosis to friends or colleagues, fearing that the knowledge that she was ill would have impeded her career, and would make it impossible to get projects financed or insured. On June 26, 2012, Ephron died at Weill Cornell Medical Center in Manhattan from pneumonia, as a complication of leukemia, at the age of 71.


title: Nora Ephron

text: Ephron's memorial service at Alice Tully Hall at Lincoln Center in New York City was attended by Meryl Streep, Tom Hanks, Billy Crystal, Meg Ryan, Rob Reiner, Barbara Walters, Diane Sawyer, Steven Spielberg, Martin Scorsese, Woody Allen, Alan Alda, Steve Martin, Martin Short, Lorne Michaels, Larry David, Joy Behar, Rosie O'Donnell, Annette Bening, Matthew Broderick, Nicole Kidman, Michael Bloomberg, Charlie Rose, Ron Howard, and Gayle King, among others.


title: Nora Ephron

text: At that year's Karlovy Vary Film Festival, actresses Helen Mirren and Susan Sarandon, who were honored with lifetime achievement awards, paid tribute to Ephron during their acceptance speeches.


title: Nora Ephron

text: Lena Dunham's 2014 memoir "Not That Kind of Girl" is dedicated to Ephron as is Steven Spielberg's film "The Post" (2017).


title: Nora Ephron

text: The Nora Ephron Prize is a $25,000 award by the Tribeca Film Festival for a female writer or filmmaker "with a distinctive voice". The first Nora Ephron Prize was awarded in 2013 to Meera Menon for her film "Farah Goes Bang".


title: Nora Ephron

text: As an actress, Nora Ephron appeared in two films, both made by her friend Woody Allen.She is credited as being a wedding guest in "Crimes and Misdemeanors" (1989), as a Dinner Party Guest in "Husbands and Wives" (1992).


title: Anemia

text: Anemia or anaemia (British English) is a blood disorder in which the blood has a reduced ability to carry oxygen due to a lower than normal number of red blood cells, or a reduction in the amount of hemoglobin. When anemia comes on slowly, the symptoms are often vague, such as tiredness, weakness, shortness of breath, headaches, and a reduced ability to exercise. When anemia is acute, symptoms may include confusion, feeling like one is going to pass out, loss of consciousness, and increased thirst. Anemia must be significant before a person becomes noticeably pale. Symptoms of anemia depend on how quickly hemoglobin decreases. Additional symptoms may occur depending on the underlying cause. Preoperative anemia can increase the risk of needing a blood transfusion following surgery. Anemia can be temporary or long term and can range from mild to severe.


title: Anemia

text: Anemia can be caused by blood loss, decreased red blood cell production, and increased red blood cell breakdown. Causes of bleeding include trauma and gastrointestinal bleeding. Causes of decreased production include iron deficiency, vitamin B12 deficiency, thalassemia and a number of bone marrow tumors. Causes of increased breakdown include genetic disorders such as sickle cell anemia, infections such as malaria, and certain autoimmune diseases. Anemia can also be classified based on the size of the red blood cells and amount of hemoglobin in each cell. If the cells are small, it is called microcytic anemia; if they are large, it is called macrocytic anemia; and if they are normal sized, it is called normocytic anemia. The diagnosis of anemia in men is based on a hemoglobin of less than 130 to 140 g/L (13 to 14 g/dL); in women, it is less than 120 to 130 g/L (12 to 13 g/dL). Further testing is then required to determine the cause.


title: Anemia

text: A large number of patients diagnosed with anemia of chronic disease present with no active inflammation or dietary issues. These include many with reduced limb loading, such as spinal cord injured patients, astronauts, elderly people with limited mobility, bed-bound and experimental bed-rest subjects.


title: Anemia

text: Certain groups of individuals, such as pregnant women, benefit from the use of iron pills for prevention. Dietary supplementation, without determining the specific cause, is not recommended. The use of blood transfusions is typically based on a person's signs and symptoms. Symptoms of anemia depend on how quickly hemoglobin decreases. In those without symptoms, they are not recommended unless hemoglobin levels are less than 60 to 80 g/L (6 to 8 g/dL). These recommendations may also apply to some people with acute bleeding. Erythropoiesis-stimulating agents are only recommended in those with severe anemia.


title: Anemia

text: Anemia is the most common blood disorder, affecting about a third of the global population. Iron-deficiency anemia affects nearly 1 billion people. In 2013, anemia due to iron deficiency resulted in about 183,000 deaths – down from 213,000 deaths in 1990. This condition is most prevalent in children with also an above average prevalence in elderly and women of reproductive age (especially during pregnancy). The name is derived from "", meaning "lack of blood", from ἀν- "an-", "not" and αἷμα "haima", "blood".


title: Anemia

text: Anemia is one of the six WHO global nutrition targets for 2025 and for diet-related global targets endorsed by World Health Assembly in 2012 and 2013. Efforts to reach global targets contribute to reaching Sustainable Development Goals (SDGs), with anemia as one of the targets in SDG 2 for achieving zero world hunger.


title: Anemia

text: Anemia is considered to be the most common blood disorder. A person with anemia may not have any symptoms, depending on the underlying cause, and no symptoms may be noticed, as the anemia is initially mild, and then the symptoms become worse as the anemia worsens. A patient with anemia may report feeling tired, weak, decreased ability to concentrate, and sometimes shortness of breath on exertion.


title: Anemia

text: Symptoms of anemia can come on quickly or slowly. Early on there may be few or no symptoms. If the anemia continues slowly (chronic), the body may adapt and compensate for this change. In this case, no symptoms may appear until the anemia becomes more severe. Symptoms can include feeling tired, weak, dizziness, headaches, intolerance to physical exertion, shortness of breath, difficulty concentrating, irregular or rapid heartbeat, cold hands and feet, cold intolerance, pale or yellow skin, poor appetite, easy bruising and bleeding, and muscle weakness. Anemia that develops quickly, often, has more severe symptoms, including, feeling faint, chest pain, sweating, increased thirst, and confusion. There may be also additional symptoms depending on the underlying cause.


title: Anemia

text: In more severe anemia, the body may compensate for the lack of oxygen-carrying capability of the blood by increasing cardiac output. The person may have symptoms related to this, such as palpitations, angina (if pre-existing heart disease is present), intermittent claudication of the legs, and symptoms of heart failure.


title: Anemia

text: On examination, the signs exhibited may include pallor (pale skin, mucosa, conjunctiva and nail beds), but this is not a reliable sign. A blue coloration of the sclera may be noticed in some cases of iron-deficiency anemia. There may be signs of specific causes of anemia, "e.g." koilonychia (in iron deficiency), jaundice (when anemia results from abnormal break down of red blood cells – in hemolytic anemia), nerve cell damage (vitamin B deficiency), bone deformities (found in thalassemia major) or leg ulcers (seen in sickle-cell disease). In severe anemia, there may be signs of a hyperdynamic circulation: tachycardia (a fast heart rate), bounding pulse, flow murmurs, and cardiac ventricular hypertrophy (enlargement). There may be signs of heart failure.


title: Anemia

text: Pica, the consumption of non-food items such as ice, paper, wax, grass, hair or dirt, may be a symptom of iron deficiency; although it occurs often in those who have normal levels of hemoglobin .


title: Anemia

text: Chronic anemia may result in behavioral disturbances in children as a direct result of impaired neurological development in infants, and reduced academic performance in children of school age. Restless legs syndrome is more common in people with iron-deficiency anemia than in the general population.


title: Anemia

text: The causes of anemia may be classified as impaired red blood cell (RBC) production, increased RBC destruction (hemolytic anemia), blood loss and fluid overload (hypervolemia). Several of these may interplay to cause anemia. The most common cause of anemia is blood loss, but this usually does not cause any lasting symptoms unless a relatively impaired RBC production develops, in turn, most commonly by iron deficiency.


title: Anemia

text: Anemias of increased red blood cell destruction are generally classified as hemolytic anemias. These types generally feature jaundice, and elevated levels of lactate dehydrogenase.


title: Anemia

text: The roots of the words "anemia" and "ischemia" both refer to the basic idea of "lack of blood", but anemia and ischemia are not the same thing in modern medical terminology. The word "anemia" used alone implies widespread "effects" from blood that either is too scarce (e.g., blood loss) or is dysfunctional in its oxygen-supplying ability (due to whatever type of hemoglobin or erythrocyte problem). In contrast, the word "ischemia" refers solely to the lack of blood (poor perfusion). Thus ischemia in a body part can cause localized anemic effects within those tissues.


title: Anemia

text: Certain gastrointestinal disorders can cause anemia. The mechanisms involved are multifactorial and not limited to malabsorption but mainly related to chronic intestinal inflammation, which causes dysregulation of hepcidin that leads to decreased access of iron to the circulation.


title: Anemia

text: There are a number of definitions of anemia; reviews provide comparison and contrast of them. A strict but broad definition is an absolute decrease in red blood cell mass, however, a broader definition is a lowered ability of the blood to carry oxygen. An operational definition is a decrease in whole-blood hemoglobin concentration of more than 2 standard deviations below the mean of an age- and sex-matched reference range.


title: Anemia

text: It is difficult to directly measure RBC mass, so the hematocrit (amount of RBCs) or the hemoglobin (Hb) in the blood are often used instead to indirectly estimate the value. Hematocrit; however, is concentration dependent and is therefore not completely accurate. For example, during pregnancy a woman's RBC mass is normal but because of an increase in blood volume the hemoglobin and hematocrit are diluted and thus decreased. Another example would be bleeding where the RBC mass would decrease but the concentrations of hemoglobin and hematocrit initially remains normal until fluids shift from other areas of the body to the intravascular space.


title: Anemia

text: The anemia is also classified by severity into mild (110 g/L to normal), moderate (80 g/L to 110 g/L), and severe anemia (less than 80 g/L) in adults. Different values are used in pregnancy and children.


title: Anemia

text: Anemia is typically diagnosed on a complete blood count. Apart from reporting the number of red blood cells and the hemoglobin level, the automatic counters also measure the size of the red blood cells by flow cytometry, which is an important tool in distinguishing between the causes of anemia. Examination of a stained blood smear using a microscope can also be helpful, and it is sometimes a necessity in regions of the world where automated analysis is less accessible.


title: Anemia

text: A blood test will provide counts of white blood cells, red blood cells and platelets. If anemia appears, further tests may determine what type it is, and whether it has a serious cause. although of that, it is possible to refer to the genetic history and physical diagnosis. These tests may include:


title: Anemia

text: Reticulocyte counts, and the "kinetic" approach to anemia, have become more common than in the past in the large medical centers of the United States and some other wealthy nations, in part because some automatic counters now have the capacity to include reticulocyte counts. A reticulocyte count is a quantitative measure of the bone marrow's production of new red blood cells. The reticulocyte production index is a calculation of the ratio between the level of anemia and the extent to which the reticulocyte count has risen in response. If the degree of anemia is significant, even a "normal" reticulocyte count actually may reflect an inadequate response.


title: Anemia

text: If an automated count is not available, a reticulocyte count can be done manually following special staining of the blood film. In manual examination, activity of the bone marrow can also be gauged qualitatively by subtle changes in the numbers and the morphology of young RBCs by examination under a microscope. Newly formed RBCs are usually slightly larger than older RBCs and show polychromasia. Even where the source of blood loss is obvious, evaluation of erythropoiesis can help assess whether the bone marrow will be able to compensate for the loss and at what rate.


title: Anemia

text: When the cause is not obvious, clinicians use other tests, such as: ESR, serum iron, transferrin, RBC folate level, hemoglobin electrophoresis, renal function tests (e.g. serum creatinine) although the tests will depend on the clinical hypothesis that is being investigated.


title: Anemia

text: When the diagnosis remains difficult, a bone marrow examination allows direct examination of the precursors to red cells, although is rarely used as is painful, invasive and is hence reserved for cases where severe pathology needs to be determined or excluded.


title: Anemia

text: In the morphological approach, anemia is classified by the size of red blood cells; this is either done automatically or on microscopic examination of a peripheral blood smear. The size is reflected in the mean corpuscular volume (MCV). If the cells are smaller than normal (under 80 fl), the anemia is said to be microcytic; if they are normal size (80–100 fl), normocytic; and if they are larger than normal (over 100 fl), the anemia is classified as macrocytic. This scheme quickly exposes some of the most common causes of anemia; for instance, a microcytic anemia is often the result of iron deficiency. In clinical workup, the MCV will be one of the first pieces of information available, so even among clinicians who consider the "kinetic" approach more useful philosophically, morphology will remain an important element of classification and diagnosis.


title: Anemia

text: Limitations of MCV include cases where the underlying cause is due to a combination of factors – such as iron deficiency (a cause of microcytosis) and vitamin B12 deficiency (a cause of macrocytosis) where the net result can be normocytic cells.


title: Anemia

text: The "kinetic" approach to anemia yields arguably the most clinically relevant classification of anemia. This classification depends on evaluation of several hematological parameters, particularly the blood reticulocyte (precursor of mature RBCs) count. This then yields the classification of defects by decreased RBC production versus increased RBC destruction or loss. Clinical signs of loss or destruction include abnormal peripheral blood smear with signs of hemolysis; elevated LDH suggesting cell destruction; or clinical signs of bleeding, such as guaiac-positive stool, radiographic findings, or frank bleeding.


title: Anemia

text: "*" "For instance, sickle cell anemia with superimposed iron deficiency; chronic gastric bleeding with B and folate deficiency; and other instances of anemia with more than one cause."


title: Anemia

text: "**" "Confirm by repeating reticulocyte count: ongoing combination of low reticulocyte production index, normal MCV and hemolysis or loss may be seen in bone marrow failure or anemia of chronic disease, with superimposed or related hemolysis or blood loss."


title: Anemia

text: Other characteristics visible on the peripheral smear may provide valuable clues about a more specific diagnosis; for example, abnormal white blood cells may point to a cause in the bone marrow.


title: Anemia

text: Microcytic anemia is primarily a result of hemoglobin synthesis failure/insufficiency, which could be caused by several etiologies:


title: Anemia

text: Iron deficiency anemia is the most common type of anemia overall and it has many causes. RBCs often appear hypochromic (paler than usual) and microcytic (smaller than usual) when viewed with a microscope.


title: Anemia

text: The Mentzer index (mean cell volume divided by the RBC count) predicts whether microcytic anemia may be due to iron deficiency or thalassemia, although it requires confirmation.


title: Anemia

text: Macrocytic anemia can be further divided into "megaloblastic anemia" or "nonmegaloblastic macrocytic anemia". The cause of megaloblastic anemia is primarily a failure of DNA synthesis with preserved RNA synthesis, which results in restricted cell division of the progenitor cells. The megaloblastic anemias often present with neutrophil hypersegmentation (six to 10 lobes). The nonmegaloblastic macrocytic anemias have different etiologies (i.e. unimpaired DNA globin synthesis,) which occur, for example, in alcoholism.


title: Anemia

text: Normocytic anemia occurs when the overall hemoglobin levels are decreased, but the red blood cell size (mean corpuscular volume) remains normal. Causes include:


title: Anemia

text: A dimorphic appearance on a peripheral blood smear occurs when there are two simultaneous populations of red blood cells, typically of different size and hemoglobin content (this last feature affecting the color of the red blood cell on a stained peripheral blood smear). For example, a person recently transfused for iron deficiency would have small, pale, iron deficient red blood cells (RBCs) and the donor RBCs of normal size and color. Similarly, a person transfused for severe folate or vitamin B12 deficiency would have two cell populations, but, in this case, the patient's RBCs would be larger and paler than the donor's RBCs. A person with sideroblastic anemia (a defect in heme synthesis, commonly caused by alcoholism, but also drugs/toxins, nutritional deficiencies, a few acquired and rare congenital diseases) can have a dimorphic smear from the sideroblastic anemia alone. Evidence for multiple causes appears with an elevated RBC distribution width (RDW), indicating a wider-than-normal range of red cell sizes, also seen in common nutritional anemia.


title: Anemia

text: Heinz bodies form in the cytoplasm of RBCs and appear as small dark dots under the microscope. In animals, Heinz body anemia has many causes. It may be drug-induced, for example in cats and dogs by acetaminophen (paracetamol), or may be caused by eating various plants or other substances:


title: Anemia

text: Refractory anemia, an anemia which does not respond to treatment, is often seen secondary to myelodysplastic syndromes. Iron deficiency anemia may also be refractory as a manifestation of gastrointestinal problems which disrupt iron absorption or cause occult bleeding.


title: Anemia

text: Transfusion dependent anemia is a form of anemia where ongoing blood transfusion are required. Most people with myelodysplastic syndrome develop this state at some point in time. Beta thalassemia may also result in transfusion dependence. Concerns from repeated blood transfusions include iron overload. This iron overload may require chelation therapy.


title: Anemia

text: Treatment for anemia depends on cause and severity. Vitamin supplements given orally (folic acid or vitamin B) or intramuscularly (vitamin B) will replace specific deficiencies.


title: Anemia

text: Nutritional iron deficiency is common in developing nations. An estimated two-thirds of children and of women of childbearing age in most developing nations are estimated to have iron deficiency without anemia; one-third of them have iron deficiency with anemia. Iron deficiency due to inadequate dietary iron intake is rare in men and postmenopausal women. The diagnosis of iron deficiency mandates a search for potential sources of blood loss, such as gastrointestinal bleeding from ulcers or colon cancer.


title: Anemia

text: Mild to moderate iron-deficiency anemia is treated by oral iron supplementation with ferrous sulfate, ferrous fumarate, or ferrous gluconate. Daily iron supplements have been shown to be effective in reducing anemia in women of childbearing age. When taking iron supplements, stomach upset or darkening of the feces are commonly experienced. The stomach upset can be alleviated by taking the iron with food; however, this decreases the amount of iron absorbed. Vitamin C aids in the body's ability to absorb iron, so taking oral iron supplements with orange juice is of benefit.


title: Anemia

text: In the anemia of chronic kidney disease, recombinant erythropoietin or epoetin alfa is recommended to stimulate RBC production, and if iron deficiency and inflammation are also present, concurrent parenteral iron is also recommended.


title: Anemia

text: In cases where oral iron has either proven ineffective, would be too slow (for example, pre-operatively), or where absorption is impeded (for example in cases of inflammation), parenteral iron preparations can be used. Parenteral iron can improve iron stores rapidly and is also effective for treating people with postpartum haemorrhage, inflammatory bowel disease, and chronic heart failure. The body can absorb up to 6 mg iron daily from the gastrointestinal tract. In many cases, the patient has a deficit of over 1,000 mg of iron which would require several months to replace. This can be given concurrently with erythropoietin to ensure sufficient iron for increased rates of erythropoiesis.


title: Anemia

text: Blood transfusions in those without symptoms is not recommended until the hemoglobin is below 60 to 80 g/L (6 to 8 g/dL). In those with coronary artery disease who are not actively bleeding transfusions are only recommended when the hemoglobin is below 70 to 80g/L (7 to 8 g/dL). Transfusing earlier does not improve survival. Transfusions otherwise should only be undertaken in cases of cardiovascular instability.


title: Anemia

text: A 2012 review concluded that when considering blood transfusions for anaemia in people with advanced cancer who have fatigue and breathlessness (not related to cancer treatment or haemorrhage), consideration should be given to whether there are alternative strategies can be tried before a blood transfusion.


title: Anemia

text: In many cases, vitamin B is used by intramuscular injection in severe cases or cases of malabsorption of dietary-B. Pernicious anemia caused by loss of intrinsic factor cannot be prevented. If there are other, reversible causes of low vitamin B levels, the cause must be treated.


title: Anemia

text: Vitamin B deficiency anemia is usually easily treated by providing the necessary level of vitamin B supplementation. The injections are quick-acting, and symptoms usually go away within one to two weeks. As the condition improves, doses are reduced to weeks and then can be given monthly. Intramuscular therapy leads to more rapid improvement and should be considered in patients with severe deficiency or severe neurologic symptoms. Treatment should begin rapidly for severe neurological symptoms, as some changes can become permanent. In some individuals lifelong treatment may be needed.


title: Anemia

text: The objective for the administration of an erythropoiesis-stimulating agent (ESA) is to maintain hemoglobin at the lowest level that both minimizes transfusions and meets the individual person's needs. They should not be used for mild or moderate anemia. They are not recommended in people with chronic kidney disease unless hemoglobin levels are less than 10 g/dL or they have symptoms of anemia. Their use should be along with parenteral iron. The 2020 Cochrane Anaesthesia Review Group review of Erythropoietin plus iron versus control treatment including placebo or iron for preoperative anaemic adults undergoing non‐cardiac surgery demonstrated that patients were much less likely to require red cell transfusion and in those transfused, the volumes were unchanged (mean difference -0.09, 95% CI -0.23 to 0.05). Pre-op Hb concentration was increased in those receiving 'high dose' EPO, but not 'low dose'.


title: Anemia

text: Treatment of exceptional blood loss (anemia) is recognized as an indication for hyperbaric oxygen (HBO) by the Undersea and Hyperbaric Medical Society. The use of HBO is indicated when oxygen delivery to tissue is not sufficient in patients who cannot be given blood transfusions for medical or religious reasons. HBO may be used for medical reasons when threat of blood product incompatibility or concern for transmissible disease are factors. The beliefs of some religions (ex: Jehovah's Witnesses) may require they use the HBO method. A 2005 review of the use of HBO in severe anemia found all publications reported positive results.


title: Anemia

text: An estimated 30% of adults who require non-cardiac surgery have anemia. In order to determine an appropriate preoperative treatment, it is suggested that the cause of anemia be first determined. There is moderate level medical evidence that supports a combination of iron supplementation and erythropoietin treatment to help reduce the requirement for red blood cell transfusions after surgery in those who have preoperative anemia.


title: Anemia

text: Anemia affects 27% of the world's population with iron-deficiency anemia accounting for more than 60% of it. A moderate degree of iron-deficiency anemia affected approximately 610 million people worldwide or 8.8% of the population. It is somewhat more common in females (9.9%) than males (7.8%). Mild iron deficiency anemia affects another 375 million. Severe anaemia is prevalent globally, and especially in sub-Saharan Africa where it is associated with infections including malaria and invasive bacterial infections.


title: Silicon

text: Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic table: carbon is above it; and germanium, tin, lead, and flerovium are below it. It is relatively unreactive.


title: Silicon

text: Because of its high chemical affinity for oxygen, it was not until 1823 that Jöns Jakob Berzelius was first able to prepare it and characterize it in pure form. Its oxides form a family of anions known as silicates. Its melting and boiling points of 1414 °C and 3265 °C, respectively, are the second highest among all the metalloids and nonmetals, being surpassed only by boron.


title: Silicon

text: Silicon is the eighth most common element in the universe by mass, but very rarely occurs as the pure element in the Earth's crust. It is widely distributed in space in cosmic dusts, planetoids, and planets as various forms of silicon dioxide (silica) or silicates. More than 90% of the Earth's crust is composed of silicate minerals, making silicon the second most abundant element in the Earth's crust (about 28% by mass), after oxygen.


title: Silicon

text: Most silicon is used commercially without being separated, often with very little processing of the natural minerals. Such use includes industrial construction with clays, silica sand, and stone. Silicates are used in Portland cement for mortar and stucco, and mixed with silica sand and gravel to make concrete for walkways, foundations, and roads. They are also used in whiteware ceramics such as porcelain, and in traditional silicate-based soda-lime glass and many other specialty glasses. Silicon compounds such as silicon carbide are used as abrasives and components of high-strength ceramics. Silicon is the basis of the widely used synthetic polymers called silicones.


title: Silicon

text: The late 20th century to early 21st century has been described as the Silicon Age (also known as the Digital Age or Information Age) because of the large impact that elemental silicon has on the modern world economy. The small portion of very highly purified elemental silicon used in semiconductor electronics (<10%) is essential to the transistors and integrated circuit chips used in most modern technology such as smartphones and other computers. In 2019, 32.4% of the semiconductor market segment was for networks and communications devices, and the semiconductors industry is projected to reach $726.73 billion by 2027.


title: Silicon

text: Silicon is an essential element in biology. Only traces are required by most animals, but some sea sponges and microorganisms, such as diatoms and radiolaria, secrete skeletal structures made of silica. Silica is deposited in many plant tissues.


title: Silicon

text: Owing to the abundance of silicon in the Earth's crust, natural silicon-based materials have been used for thousands of years. Silicon rock crystals were familiar to various ancient civilizations, such as the predynastic Egyptians who used it for beads and small vases, as well as the ancient Chinese. Glass containing silica was manufactured by the Egyptians since at least 1500 BC, as well as by the ancient Phoenicians. Natural silicate compounds were also used in various types of mortar for construction of early human dwellings.


title: Silicon

text: In 1787, Antoine Lavoisier suspected that silica might be an oxide of a fundamental chemical element, but the chemical affinity of silicon for oxygen is high enough that he had no means to reduce the oxide and isolate the element. After an attempt to isolate silicon in 1808, Sir Humphry Davy proposed the name "silicium" for silicon, from the Latin "silex", "silicis" for flint, and adding the "-ium" ending because he believed it to be a metal. Most other languages use transliterated forms of Davy's name, sometimes adapted to local phonology (e.g. German "Silizium", Turkish "silisyum", Catalan "silici", Armenian "Սիլիցիում" or "Silitzioum"). A few others use instead a calque of the Latin root (e.g. Russian "кремний", from "кремень" "flint"; Greek "πυρίτιο" from "πυρ" "fire"; Finnish "pii" from "piikivi" "flint", Czech "křemík" from "křemen" "quartz", "flint").


title: Silicon

text: Gay-Lussac and Thénard are thought to have prepared impure amorphous silicon in 1811, through the heating of recently isolated potassium metal with silicon tetrafluoride, but they did not purify and characterize the product, nor identify it as a new element. Silicon was given its present name in 1817 by Scottish chemist Thomas Thomson. He retained part of Davy's name but added "-on" because he believed that silicon was a nonmetal similar to boron and carbon. In 1824, Jöns Jacob Berzelius prepared amorphous silicon using approximately the same method as Gay-Lussac (reducing potassium fluorosilicate with molten potassium metal), but purifying the product to a brown powder by repeatedly washing it. As a result, he is usually given credit for the element's discovery. The same year, Berzelius became the first to prepare silicon tetrachloride; silicon tetrafluoride had already been prepared long before in 1771 by Carl Wilhelm Scheele by dissolving silica in hydrofluoric acid.


title: Silicon

text: Silicon in its more common crystalline form was not prepared until 31 years later, by Deville. By electrolyzing a mixture of sodium chloride and aluminium chloride containing approximately 10% silicon, he was able to obtain a slightly impure allotrope of silicon in 1854. Later, more cost-effective methods have been developed to isolate several allotrope forms, the most recent being silicene in 2010. Meanwhile, research on the chemistry of silicon continued; Friedrich Wöhler discovered the first volatile hydrides of silicon, synthesising trichlorosilane in 1857 and silane itself in 1858, but a detailed investigation of the silanes was only carried out in the early 20th century by Alfred Stock, despite early speculation on the matter dating as far back as the beginnings of synthetic organic chemistry in the 1830s. Similarly, the first organosilicon compound, tetraethylsilane, was synthesised by Charles Friedel and James Crafts in 1863, but detailed characterisation of organosilicon chemistry was only done in the early 20th century by Frederic Kipping.


title: Silicon

text: Starting in the 1920s, the work of William Lawrence Bragg on X-ray crystallography successfully elucidated the compositions of the silicates, which had previously been known from analytical chemistry but had not yet been understood, together with Linus Pauling's development of crystal chemistry and Victor Goldschmidt's development of geochemistry. The middle of the 20th century saw the development of the chemistry and industrial use of siloxanes and the growing use of silicone polymers, elastomers, and resins. In the late 20th century, the complexity of the crystal chemistry of silicides was mapped, along with the solid-state physics of doped semiconductors.


title: Silicon

text: The first semiconductor devices did not use silicon, but used galena, including German physicist Ferdinand Braun's crystal detector in 1874 and Indian physicist Jagadish Chandra Bose's radio crystal detector in 1901. The first silicon semiconductor device was a silicon radio crystal detector, developed by American engineer Greenleaf Whittier Pickard in 1906.


title: Silicon

text: In 1940, Russell Ohl discovered the p–n junction and photovoltaic effects in silicon. In 1941, techniques for producing high-purity germanium and silicon crystals were developed for radar microwave detector crystals during World War II. In 1947, physicist William Shockley theorized a field-effect amplifier made from germanium and silicon, but he failed to build a working device, before eventually working with germanium instead. The first working transistor was a point-contact transistor built by John Bardeen and Walter Brattain later that year while working under Shockley. In 1954, physical chemist Morris Tanenbaum fabricated the first silicon junction transistor at Bell Labs. In 1955, Carl Frosch and Lincoln Derick at Bell Labs accidentally discovered that silicon dioxide () could be grown on silicon, and they later proposed this could mask silicon surfaces during diffusion processes in 1958.


title: Silicon

text: The "Silicon Age" refers to the late 20th century to early 21st century. This is due to silicon being the dominant material of the Silicon Age (also known as the Digital Age or Information Age), similar to how the Stone Age, Bronze Age and Iron Age were defined by the dominant materials during their respective ages of civilization.


title: Silicon

text: Because silicon is an important element in high-technology semiconductor devices, many places in the world bear its name. For example, Santa Clara Valley in California acquired the nickname Silicon Valley, as the element is the base material in the semiconductor industry there. Since then, many other places have been dubbed similarly, including Silicon Wadi in Israel, Silicon Forest in Oregon, Silicon Hills in Austin, Texas, Silicon Slopes in Salt Lake City, Utah, Silicon Saxony in Germany, Silicon Valley in India, Silicon Border in Mexicali, Mexico, Silicon Fen in Cambridge, England, Silicon Roundabout in London, Silicon Glen in Scotland, Silicon Gorge in Bristol, England, Silicon Alley in New York, New York and Silicon Beach in Los Angeles, California.


title: Silicon

text: A silicon atom has fourteen electrons. In the ground state, they are arranged in the electron configuration [Ne]3s3p. Of these, four are valence electrons, occupying the 3s orbital and two of the 3p orbitals. Like the other members of its group, the lighter carbon and the heavier germanium, tin, and lead, it has the same number of valence electrons as valence orbitals: hence, it can complete its octet and obtain the stable noble gas configuration of argon by forming sp hybrid orbitals, forming tetrahedral derivatives where the central silicon atom shares an electron pair with each of the four atoms it is bonded to. The first four ionisation energies of silicon are 786.3, 1576.5, 3228.3, and 4354.4 kJ/mol respectively; these figures are high enough to preclude the possibility of simple cationic chemistry for the element. Following periodic trends, its single-bond covalent radius of 117.6 pm is intermediate between those of carbon (77.2 pm) and germanium (122.3 pm). The hexacoordinate ionic radius of silicon may be considered to be 40 pm, although this must be taken as a purely notional figure given the lack of a simple cation in reality.


title: Silicon

text: At standard temperature and pressure, silicon is a shiny semiconductor with a bluish-grey metallic lustre; as typical for semiconductors, its resistivity drops as temperature rises. This arises because silicon has a small energy gap (band gap) between its highest occupied energy levels (the valence band) and the lowest unoccupied ones (the conduction band). The Fermi level is about halfway between the valence and conduction bands and is the energy at which a state is as likely to be occupied by an electron as not. Hence pure silicon is effectively an insulator at room temperature. However, doping silicon with a pnictogen such as phosphorus, arsenic, or antimony introduces one extra electron per dopant and these may then be excited into the conduction band either thermally or photolytically, creating an n-type semiconductor. Similarly, doping silicon with a group 13 element such as boron, aluminium, or gallium results in the introduction of acceptor levels that trap electrons that may be excited from the filled valence band, creating a p-type semiconductor. Joining n-type silicon to p-type silicon creates a p–n junction with a common Fermi level; electrons flow from n to p, while holes flow from p to n, creating a voltage drop. This p–n junction thus acts as a diode that can rectify alternating current that allows current to pass more easily one way than the other. A transistor is an n–p–n junction, with a thin layer of weakly p-type silicon between two n-type regions. Biasing the emitter through a small forward voltage and the collector through a large reverse voltage allows the transistor to act as a triode amplifier.


title: Silicon

text: Silicon crystallises in a giant covalent structure at standard conditions, specifically in a diamond cubic lattice (). It thus has a high melting point of 1414 °C, as a lot of energy is required to break the strong covalent bonds and melt the solid. Upon melting silicon contracts as the long-range tetrahedral network of bonds breaks up and the voids in that network are filled in, similar to water ice when hydrogen bonds are broken upon melting. It does not have any thermodynamically stable allotropes at standard pressure, but several other crystal structures are known at higher pressures. The general trend is one of increasing coordination number with pressure, culminating in a hexagonal close-packed allotrope at about 40 gigapascals known as Si–VII (the standard modification being Si–I). An allotrope called BC8 (or bc8), having a body-centred cubic lattice with eight atoms per primitive unit cell (), can be created at high pressure and remains metastable at low pressure. Its properties have been studied in detail.


title: Silicon

text: Silicon boils at 3265 °C: this, while high, is still lower than the temperature at which its lighter congener carbon sublimes (3642 °C) and silicon similarly has a lower heat of vaporisation than carbon, consistent with the fact that the Si–Si bond is weaker than the C–C bond.


title: Silicon

text: Naturally occurring silicon is composed of three stable isotopes, Si (92.23%), Si (4.67%), and Si (3.10%). Out of these, only Si is of use in NMR and EPR spectroscopy, as it is the only one with a nuclear spin ("I" =). All three are produced in Type Ia supernovae through the oxygen-burning process, with Si being made as part of the alpha process and hence the most abundant. The fusion of Si with alpha particles by photodisintegration rearrangement in stars is known as the silicon-burning process; it is the last stage of stellar nucleosynthesis before the rapid collapse and violent explosion of the star in question in a type II supernova.


title: Silicon

text: Twenty radioisotopes have been characterized, the two stablest being Si with a half-life of about 150 years, and Si with a half-life of 2.62 hours. All the remaining radioactive isotopes have half-lives that are less than seven seconds, and the majority of these have half-lives that are less than one tenth of a second. Silicon has one known nuclear isomer, Si, with a half-life less than 210 nanoseconds. Si undergoes low-energy beta decay to P and then stable S. Si may be produced by the neutron activation of natural silicon and is thus useful for quantitative analysis; it can be easily detected by its characteristic beta decay to stable P, in which the emitted electron carries up to 1.48 MeV of energy.


title: Silicon

text: The known isotopes of silicon range in mass number from 22 to 44. The most common decay mode of the isotopes with mass numbers lower than the three stable isotopes is inverse beta decay, primarily forming aluminium isotopes (13 protons) as decay products. The most common decay mode for the heavier unstable isotopes is beta decay, primarily forming phosphorus isotopes (15 protons) as decay products.


title: Silicon

text: Silicon can enter the oceans through groundwater and riverine transport. Large fluxes of groundwater input have an isotopic composition which is distinct from riverine silicon inputs. Isotopic variations in groundwater and riverine transports contribute to variations in oceanic Si values. Currently, there are substantial differences in the isotopic values of deep water in the world's ocean basins. Between the Atlantic and Pacific oceans, there is a deep water Si gradient of greater than 0.3 parts per thousand. Si is most commonly associated with productivity in the oceans.


title: Silicon

text: Crystalline bulk silicon is rather inert, but becomes more reactive at high temperatures. Like its neighbour aluminium, silicon forms a thin, continuous surface layer of silicon dioxide () that protects the metal from oxidation. Thus silicon does not measurably react with the air below 900 °C, but formation of the vitreous dioxide rapidly increases between 950 °C and 1160 °C and when 1400 °C is reached, atmospheric nitrogen also reacts to give the nitrides SiN and . Silicon reacts with gaseous sulfur at 600 °C and gaseous phosphorus at 1000 °C. This oxide layer nevertheless does not prevent reaction with the halogens; fluorine attacks silicon vigorously at room temperature, chlorine does so at about 300 °C, and bromine and iodine at about 500 °C. Silicon does not react with most aqueous acids, but is oxidised and complexed by hydrofluoric acid mixtures containing either chlorine or nitric acid to form hexafluorosilicates. It readily dissolves in hot aqueous alkali to form silicates. At high temperatures, silicon also reacts with alkyl halides; this reaction may be catalysed by copper to directly synthesise organosilicon chlorides as precursors to silicone polymers. Upon melting, silicon becomes extremely reactive, alloying with most metals to form silicides, and reducing most metal oxides because the heat of formation of silicon dioxide is so large. In fact, molten silicon reacts virtually with every known kind of crucible material (except its own oxide, ). This happens due to silicon's high binding forces for the light elements and to its high dissolving power for most elements. As a result, containers for liquid silicon must be made of refractory, unreactive materials such as zirconium dioxide or group 4, 5, and 6 borides.


title: Silicon

text: Tetrahedral coordination is a major structural motif in silicon chemistry just as it is for carbon chemistry. However, the 3p subshell is rather more diffuse than the 2p subshell and does not hybridise so well with the 3s subshell. As a result, the chemistry of silicon and its heavier congeners shows significant differences from that of carbon, and thus octahedral coordination is also significant. For example, the electronegativity of silicon (1.90) is much less than that of carbon (2.55), because the valence electrons of silicon are further from the nucleus than those of carbon and hence experience smaller electrostatic forces of attraction from the nucleus. The poor overlap of 3p orbitals also results in a much lower tendency toward catenation (formation of Si–Si bonds) for silicon than for carbon, due to the concomitant weakening of the Si–Si bond compared to the C–C bond: the average Si–Si bond energy is approximately 226 kJ/mol, compared to a value of 356 kJ/mol for the C–C bond. This results in multiply bonded silicon compounds generally being much less stable than their carbon counterparts, an example of the double bond rule. On the other hand, the presence of radial nodes in the 3p orbitals of silicon suggests the possibility of hypervalence, as seen in five and six-coordinate derivatives of silicon such as and . Lastly, because of the increasing energy gap between the valence s and p orbitals as the group is descended, the divalent state grows in importance from carbon to lead, so that a few unstable divalent compounds are known for silicon; this lowering of the main oxidation state, in tandem with increasing atomic radii, results in an increase of metallic character down the group. Silicon already shows some incipient metallic behavior, particularly in the behavior of its oxide compounds and its reaction with acids as well as bases (though this takes some effort), and is hence often referred to as a metalloid rather than a nonmetal. However, metallicity does not become clear in group 14 until germanium and dominant until tin, with the growing importance of the lower +2 oxidation state.


title: Silicon

text: Silicon shows clear differences from carbon. For example, organic chemistry has very few analogies with silicon chemistry, while silicate minerals have a structural complexity unseen in oxocarbons. Silicon tends to resemble germanium far more than it does carbon, and this resemblance is enhanced by the d-block contraction, resulting in the size of the germanium atom being much closer to that of the silicon atom than periodic trends would predict. Nevertheless, there are still some differences because of the growing importance of the divalent state in germanium compared to silicon, which result in germanium being significantly more metallic than silicon. Additionally, the lower Ge–O bond strength compared to the Si–O bond strength results in the absence of "germanone" polymers that would be analogous to silicone polymers.


title: Silicon

text: Many metal silicides are known, most of which have formulae that cannot be explained through simple appeals to valence: their bonding ranges from metallic to ionic and covalent. Some known stoichiometries are , , , , , , , , , MSi, , , , and . They are structurally more similar to the borides than the carbides, in keeping with the diagonal relationship between boron and silicon, although the larger size of silicon than boron means that exact structural analogies are few and far between. The heats of formation of the silicides are usually similar to those of the borides and carbides of the same elements, but they usually melt at lower temperatures. Silicides are known for all stable elements in groups 1–10, with the exception of beryllium: in particular, uranium and the transition metals of groups 4–10 show the widest range of stoichiometries. Except for copper, the metals in groups 11–15 do not form silicides. Instead, most form eutectic mixtures, although the heaviest post-transition metals mercury, thallium, lead, and bismuth are completely immiscible with liquid silicon.


title: Silicon

text: Usually, silicides are prepared by direct reaction of the elements. For example, the alkali metals and alkaline earth metals react with silicon or silicon oxide to give silicides. Nevertheless, even with these highly electropositive elements true silicon anions are not obtainable, and most of these compounds are semiconductors. For example, the alkali metal silicides contain pyramidal tricoordinate silicon in the anion, isoelectronic with white phosphorus, . Metal-rich silicides tend to have isolated silicon atoms (e. g. ); with increasing silicon content, catenation increases, resulting in isolated clusters of two (e. g. ) or four silicon atoms (e. g. ) at first, followed by chains (e. g. CaSi), layers (e. g. ), or three-dimensional networks of silicon atoms spanning space (e. g. ) as the silicon content rises even higher.


title: Silicon

text: The silicides of the group 1 and 2 metals usually are more reactive than the transition metal silicides. The latter usually do not react with aqueous reagents, except for hydrofluoric acid; however, they do react with much more aggressive reagents such as liquid potassium hydroxide, or gaseous fluorine or chlorine when red-hot. The pre-transition metal silicides instead readily react with water and aqueous acids, usually producing hydrogen or silanes:


title: Silicon

text: Products often vary with the stoichiometry of the silicide reactant. For example, is polar and non-conducting and has the anti- structure with single isolated silicon atoms, and reacts with water to produce calcium hydroxide, hydrated silicon dioxide, and hydrogen gas. CaSi with its zigzag chains of silicon atoms instead reacts to give silanes and polymeric , while with its puckered layers of silicon atoms does not react with water, but will react with dilute hydrochloric acid: the product is a yellow polymeric solid with stoichiometry .


title: Silicon

text: Speculation on silicon hydride chemistry started in the 1830s, contemporary with the development of synthetic organic chemistry. Silane itself, as well as trichlorosilane, were first synthesised by Friedrich Wöhler and Heinrich Buff in 1857 by reacting aluminium–silicon alloys with hydrochloric acid, and characterised as and by Charles Friedel and Albert Ladenburg in 1867. Disilane ) followed in 1902, when it was first made by Henri Moissan and Samuel Smiles by the protonolysis of magnesium silicides. Further investigation had to wait until 1916 because of the great reactivity and thermal instability of the silanes; it was then that Alfred Stock began to study silicon hydrides in earnest with new greaseless vacuum techniques, as they were found as contaminants of his focus, the boron hydrides. The names "silanes" and "boranes" are his, based on analogy with the alkanes. The Moissan and Smiles method of preparation of silanes and silane derivatives via protonolysis of metal silicides is still used, although the yield is lowered by the hydrolysis of the products that occurs simultaneously, so that the preferred route today is to treat substituted silanes with hydride reducing agents such as lithium aluminium hydride in etheric solutions at low temperatures. Direct reaction of HX or RX with silicon, possibly with a catalyst such as copper, is also a viable method of producing substituted silanes.