We can see your screen. See a slide. Yep. We see slides. Very good. Thanks so much, Megan. My name's Liz. I'm presenting from Wurundjeri country. Always was always will be Wurundjeri country. I'm talking about taxonomy or vocabulary projects that I led a few not too many years ago now at the analysis and policy observatory. I barely have time to explain what apo.org.au is, but do visit it sometime. It's a digital library with policy information. It's got a great search interface. I'm going to be talking about a vocabulary project there as a case study. And then I'm going to offer some reflections about what about things like tools and governance and techniques, you know, that we encountered and used during the process. I guess just quickly the short answer to the question how the public taxonomy was made was really in that photograph there. That was the team when I was there. And it was really, I think just a quick reflection is that vocabularies and vocabulary projects really do impact every corner of an organization. You can probably imagine how vocabs and changes to vocabs impact the website development sort of area. It's also editors and catalogs, people who sort of create the value in these digital libraries. It's also leadership. I think Amanda might even be here today. But really you need to get leaders involved in defining the scope and the purpose of the vocabulary. It's important to have that sort of buy in. But even marketing as well. And we'll see that vocabularies used at APA were used to organize, you know, marketing products sort of thing. So everyone was impacted and everyone helped me with this project and it was a wonderful, wonderful experience. The reason that we were doing the project was because of a project called the link semantic platforms, which was an ARC funded project involving a few agencies. And one of the objectives of the project was to make APO taxonomies shareable. In fact, I think it was actually taxonomy in the singular. But we'll see how interesting that situation was about the plurality of the vocabularies. I'm going to dive straight into this slide, which is this is not a screenshot. This is actually a mock-up that I've created. But this is a true representation of something I encountered when I first started working at APO. So imagine that you're looking at a description of some metadata and a description of an article. And you like the look of what you see and you want to explore and find some other things that are similar. And on the right-hand side, you've got some links. But of course, you've found that you've got the word economics three times under different headings. So when I encountered this situation, my first thought was, well, there's some significant usability issues here, no matter what's going on behind these fields. But the other thing that occurred to me was, I'm sure there's an interesting story that took behind each of these fields. And it was part of my job was to uncover and document that story and to get requirements out of that investigation. It did remind me slightly of the multi-haul problem, but that's a digression. So excuse me, we skipped ahead. First of all, subject. What did subject mean? Well, it was a subset of the faceted application of subject terms or fast. And it was really there in the APO database because it had been sort of adopted after a minute out of harvest. Luckily, the fast IDs had been retained and that's an important factoid for this presentation. And also, APO had a seat in the fast working group. So APO was actually contributing directly into the working group for the development of fasts. Secondly, broad subjects. Now, the broad subjects was a short list, 15 or actually 13 topics at the time. And it was really there to address a system limitation where it was difficult to pull out a top level from the subjects. I think mainly because the subjects was itself a subset of another vocabulary. I noticed that some alignment work had been done to align the broad subjects with the fields of research, which is an Australian research classification system. And that I had to continue some of the alignment work as well. And the broad subjects were very important in driving marketing, such as newsletters and certain parts of the website and things and generation of icons and things like this. And last keyword, so what was the keyword? Essentially, it was a term that was not in fast, but we needed the term. It's not entirely true. Some of the terms that were in the keywords were also in fast. But the two of the terms that the editors came up with, so the people doing the cataloging came up with these terms and they stored them in the database as well. And I thought it was quite interesting that the keywords were referred to internally as an uncontrolled vocabulary. And I thought that was interesting. So the fast terms were regarded as controlled. The keywords were regarded as uncontrolled. And I took the editors a little bit of a journey there exploring the idea that maybe there was different types of control that were being applied. And there was certainly rules involved in how the editors decided what was the keyword and what wasn't. And I sort of led the move to document those rules and to refine those rules as well, taking them away from this idea that there was a controlled and an uncontrolled vocabulary. So to make a taxonomy shareable, there are a few things I needed to do. And so I've got this in five steps. And I just want to quickly mention that when I created this slide, I asked Microsoft PowerPoint to come up with some icons and it came up with the dinosaur for the third step. Can only imagine that's because of the Thesaurus Rex cartoon that probably many of you are familiar with. I thought I'd leave the dinosaur ring because I thought it was funny. I'll take you through these one at a time. First of all, improve the improve the keywords taxonomy. The reason I wanted to start with the keywords is because that is basically where the value was that API had created API created this word stock by keeping these keywords and this is over several years. Yeah. So this was API's intellectual property, if you like. The only problem with the keywords was that it had a very long tail of low use terms. So many terms that had only been used once or twice. And that's not surprising because sentence were not being controlled hierarchy was not being established. And the tools for looking up the terms in the database were a bit clunky. So it was very difficult to keep track of what had been added and where there were duplications in whether labels or meaning. So we worked with the data sciences at Swinburne, Yongbin Kang and very clever guy who use something called a subsumption method. This was some artificial intelligence method to identify co-occurrence between terms. And we had that checked by API editors and manual checking of the artificial intelligence and training the AI. And this helped me to clean up the tail. This helped me to find many synonyms and to assert those synonyms relationships. Wrong way. Sorry. Secondly, once that cleaning up of the long tail was done, it was time to merge the vocabularies. And there was a little bit of hesitation around the team. I have to say about this idea of merging the subjects, so-called subjects with the keywords. And I think I mitigated those concerns by saying we're keeping the fast IDs in the terms that had the fast IDs. So we'll always know that these were taken from fast. I also brought in some more metadata from fast like some of the alternative labels that were stored there that hadn't been imported before. Because we're starting to store synonyms for the first time at APO. And once that merge had been completed, I started applying, you know, more the Soros conventions, making sure that there was a full hierarchy, also associations, cleaning up orphans, terms that had no relationships. There were more synonyms from this process, which was great. We implemented those in the search engine. More updating of catalogs and cataloging forms and guides and so on. I'm going to go through this one a little bit more slowly if I've got time, I think. So to enrich the one taxonomy that we had now, I used the term analysis where we found that we had high-use terms. We targeted those terms to make more matches with fasts. And so we used a Scotts exact match relationship to those fast terms, which we were able to do because we have retained the IDs. But also, there's another vocabulary that was relevant to this project, APACE or the Australian Public Affairs Information Service, the Soros. It was a vocabulary that really is only officially published if you like, you know, in print format. It has not been maintained for some time. But one of our partners in the project, which was Australian data archive, you may have heard of them, was using APACE and its database. And so it made sense to us to do some mapping between our taxonomy and APACE. And this was an interesting story because I wanted a copy of APACE to import into the research vocabularies Australia editor. And I had a bit of trouble finding a machine-readable copy. I did approach the National Library of Australia, who's from what I could work out, owned APACE. They told me that I should go and talk to RMIT Training because they were managing APACE now. I said, okay, fine. So I went to RMIT Training and they told me I'd better go back to the National Library of Australia to get a copy of that. So I ended up using sort of an unofficial version that I found on the web. So I pulled that into the research vocabularies Australia editor and I used that to do the mapping. I'll show you a bit more about how the mapping was done. We also matched terms from our vocab with AGIFT, or the Australian Government Interactive Function Cessaurus, which made sense to APA because probably half of our audience was government as well as the other half being a sort of research or academic audience. And that was AGIFT was at the time hosted by the National Archives. I understand there's a bit of movement as to where AGIFT sits and how it's being managed. So some of those links have probably broken now. Also matching with the fields of research codes or these research classifications that we use in Australia. So instead of just having the top level of the terms aligned with the fields of research, I actually made machine readable links to those research codes for all the high use terms, I guess, in the Thesaurus. All this work resulted in more synonyms, which was wonderful and really enriched the Thesaurus structure so there was lots of synonym control. I had pulled a couple of these external vocabularies into the research vocabularies Australia editor, and it has a nice batch linking feature, which means that it can automatically detect where there are matches between vocabularies, but also makes it protection using alternative labels as well as preferred labels. So that's a really neat little feature there. Step number five, publish. So the public policy taxonomy is published at Research Vocabularies Australia in RDF and all the formats that you would expect to find, I suppose. We set up a bit of an interesting situation where we have the Thesaurus or taxonomy is managed there in pool party. It pushes a version back to Drupal, and when Drupal creates a new taxonomy page, the token that it creates is then copied back into Research Vocabularies Australia as a slightly messy manual step there at the end, but it works. The taxonomy is still being maintained, which is really good. And it's available over a slightly restrictive Creative Commons license. Just some quick reflections. I found it difficult to establish a community of practice for feedback into the public policy taxonomy. Policy is certainly a multi-domain area. It's a very multi-domain area. It's not the whole of knowledge, but it's an awful lot of things. It's anything that could be governed, I suppose. And while we had some special interest groups, for example, we would have a project decolonizing the taxonomy. We never really established, I think, probably a good ongoing source of feedback from the policy community. It's probably something that I would like to have done if I'd stayed in the project longer. 15 minutes, Liz, 15 minutes. Rules of engagement were unclear, as I think I've indicated, with things like approaching, you know, National Archives or the National Library or whoever, about things like A-Pace and A-Gift. And trying to understand, you know, could we, should we work with these vocabularies? How should we, what are the rules? They seem to be a little unclear at times. We never actually established proper URIs for the public policy taxonomy. We only use the ones that were generated by the software there. I was advised, thank you, Rowan, by you that I should approach the Australian Government Link Data Working Group to get that sorted out. I never got that far, although I will say at the time that it seemed an odd idea to approach a working group about something that would seem to be a service. I've already learned today that there's been some movement in this area. So I think I'm really interested to find out what happens with providing a URI service to people working in that environment. And also, yes, consuming the vocabulary back into Drupal, we weren't doing that as using sort of an open data situation. We had an application-to-application connection, which is a little bit of a non-standard thing to do, which is not, I suppose in a sense it's not great because if I was ever asked, you know, how should I integrate this with a system, I didn't have a very good example to point out. Okay. Thanks, Rowan. I'm finishing.


Thanks a lot Patricia. Hi everyone. So I'll be presenting a paper called arm groups taxation and fishing in the Zamboanga Peninsula in the Philippines So I'm good to Marche and I'm presenting on behalf of a wider team led by Anna Maria Ibanez from Universidad de los Andes Teresita Narváez from Western Mindanao State University and Patricia Justino from UNU wider and IDS and there was also Maria Adelaida Ortega, Manuel de Vera, Ryan Tingelin, Benjamin Cross and Jorge Maldonado. I just wanted to say that I'm not an expert on the Philippines I work on the effects of island conflict mostly in Central Africa But I was very happy to be part of this project and to present on behalf of this team So I just wanted to say something about the rationale of the project So we know that there is a strong and negative environmental impact of island conflict Generally tied to destruction, tied to the cost of war, tied to pollution, to deregulation And that there is a direct impact also on priority environmental regions such as the Amazon, the Congo Basin, the Sahel and the Philippines Archipelago, but there is limited disaggregated evidence of the impact on the environment We know that conflict affected regions are heterogeneous They're mocked by strong variation in terms of political, social, economic organization and that can condition variegated impacts on the environment We also know that control over environmental resources such as land, forests and the sea are key stakes in violent conflict And that environmental conservation has often been exposed by external actors Be it colonial states, contemporary states, even NGOs Along with other forms of impositions and notably taxation and that's these impositions And conservation impositions can be part of grievances that underpin supports for insurgent groups Another important aspect is the role of local communities So we know that the communal management of environmental resources is key for environmental protection We can think about the work of Eleanor Ostrom or Abinah Agarwal But communities are severely impacted by the presence of armed groups through violence, of course But also through taxation, which is really a hallmark of contemporary violent conflict But also through other forms of interference and governance by armed groups that has been documented by the literature on wartime political order and rebel governance and this is likely to impact communal management of environmental resources yet There is limited disaggregated evidence on this issue and particularly in the fishing sector which has received Relatively little attention in the literature on violent conflict. So this led us to our two research questions first How does the presence of armed groups affect the fishing sector and environmental protection and what are the implications for policy interventions? Today I'll be presenting some preliminary results of what is a non-going analysis and key work done by this summer by Maria Adelaida Ortega and this will be published as a UNU wider working paper hopefully in early 2024 So a bit about the project So the project is a partnership between Universidad de los Andes in Colombia the Western Minda now a state university in the Philippines in Zambonga City and the Institute of Development Studies in the UK The data collection was funded by the UK Economic and Social Research Council and this paper is Funded also by the UNU wider The project focuses on municipal fishing communities in Zambonga Peninsula, which is in the south of the Philippines on the island of Mindanao It's to it's the peninsula to the west of the island of Mindanao The peninsula is actually the largest sardines exporting region in the Philippines It represents 70% of the Philippines production of sardines There is a large industrial fishing sector which actually is its presence is historically tied to the history of colonialism in the region and There has been long-standing Historical tensions with the municipal fishing sector, which also is very much developed around along the coastal areas of the Zambonga Peninsula But also the Sulu archipelago So there's this long-standing tension between the industrial fishing sector the municipal fishing sector and in 2011 There was a conservation measure imposed Seasonal fishing ban and I'll come back to that if there is some time So the project use a mixed methods approached with on one side a quantitative component a survey of 1,500 fishing households in 59 barangays. There was also Community surveys at the barangay level with community leaders in these 59 barangays in the Zambonga Peninsula And a smaller qualitative component which was composed of 32 key informant interviews with Fisher folk military authorities industrial fishers State representatives and a set of other actors experts on the question on this question in the Philippines And the expertise of the Western Mindanao State University on fishing in the Zambonga Peninsula was very much leveraged by the project as Well as the expertise of the University that they losundice on the effects of island conflict, but also on fishing So Importantly the Zambonga Peninsula as the island of Mindanao has been marked by a long-standing history of armed insurgency Which is historically tied to moral nationalism? historical nationalism and resistance and including armed resistance against Spanish occupation against the United States against Japan and Since 1946 the independence of the Philippines against the central government of the Philippines Conceived to some extent as being a colonial actor within the region and there are these large large and long-standing Rebel groups the Moro national liberation front the MNLF and the moral Islamic liberation from the front the MILF and Then a constellation of other armed groups some notorious ones being the Abu Sayyaf group Which has historical links to Al Qaeda and more recently the Islamic States And the bank Samora Islamic freedom fighters and then a constellation of other armed groups There is also on the island of Mindanao a long-standing communist insurgency the new people's army that emerged in 1969 the project itself actually happened at a critical juncture, so Most of the data collection was carried out in 2019 and 2020 There were then delays tied to the COVID pandemic and the restrictions at the moment But this was a historical moment because in 2014 there was a peace agreement signed between the moral Islamic liberation front and the government which led to the creation of the Bank Samora autonomous region in Muslim Mindanao Which is an autonomous region within the Philippines and very much a historical moment in the in the history of the country So a critical juncture But also an interesting configuration of the project because the Zambuanga Peninsula where we carried out the study is Not part of the Bank Samora autonomous region in Muslim Mindanao But it's adjacent to it and it has the presence of the armed groups on the peninsula and here on this map you can see These are the bearing gays where the survey was carried out and you can see in red So in the provinces of Zambuanga del Norte Zambuanga del Sur and Zambuanga Sibugai And you can see in red those barangays where there is the presence of armed groups So I wanted to say some things about the dynamics of violence in Zambuanga Peninsula. They're very complex There are several levels. There is first of all combat for control territorial control political influence and resources between these large insurgent groups the national army and then a constellation of other groups There is also a political economy of piracy of extortion of kidnapping for ransom that has emerged over the last decades And there is also a strong implantation of the drug trade particularly in Zambuanga City There is also the the persisting importance of clan politics and also clan related violence Ritualized violence known as Rideau Overall there has been a general decrease in violence since the 2010s. This is a Philippine military officials who have been telling us this and you can see the evolution of the different types of violence that we found In the barangays, which we studied on these graphs And what we found was clear evidence of targeting by armed actors of the fishing industry First of all violent extortion by the larger armed groups, but also by a constellation of the other smaller groups targeting industrial fishing so industrial fishing vessels and then complex elite arrangements between the industrial fishing sector and the National Army on one side, but even The non-state armed groups on the other and these have been studied by Manuel de Vera who was part of this project And who wrote a dissertation on this topic There are also conflicts in the fishing sector Conflicts around fishing zones fishing gear catch that can lead to violence and this is something that has been observed across the world There's a recent article by Lou and Yamazaki On Indonesia where they document similar types of fishing wars and fishing conflicts Yet there is little empirical evidence of the effects on municipal fishing, which was the focus of this project so here I'm going to present some Descriptives and preliminary data on that that that we we found so first of all we found evidence of a strong implantation of the armed groups Particularly the MILF more Islamic Liberation Front and then groups designated as pirates Which is actually a wide range of groups that can be of various size and varying Affiliation with the larger armed insurgencies and we can see that the presence It's much stronger in Zambuanga, Sibugei and Zambuanga del Sur than in Zambuanga del Norte We find for example here you can see on the graph that 69.2% of community leaders in Zambuanga del Sur say that the armed groups are present in their barangay against Only 8.7% in Zambuanga del Norte The presence of these groups is very much covert rather than overt This is something that I'll come back to at the end There is evidence also that the armed groups provide various forms of public services in particular various forms of protection But sometimes they actually build schools or they can be involved in the building of public infrastructure And then there is evidence of far-reaching social networks of these groups within the population and we use basic measures of social networks Here you can see that for example in Zambuanga del Sur 26.9% of the households that were interviewed say that they have an acquaintance either a family member or a friend that is part of one of these armed groups So this is really an indication of a very very strong social penetration One could say of these armed groups a social penetration also within the fishing sector because In Zambuanga del Sur for example 18.9% of the households interviewed say that the traders that buy their fish because these are municipal fishing households Are related to the armed groups so an invocation of the armed groups within the fish trade? We then found a further evidence of interference what we call interference in the fishing sector through the form of taxation and rudimentary forms of governance The main form of presence is taxation. So in Zambuanga del Sur 17.1% of households say that armed groups collect taxes It's not a huge number, but it's nevertheless a consequential number. I would say And 15.4% in Zambuanga Sibuge The taxes collected by armed groups are levied both in money and in fish and they're informed enforced by sanctions both violence and various forms of harassment on fisherfolk There is also some evidence of interference in the governance of fishing sector of the fishing sector We can see here in panel B some descriptives around governance For example in Zambuanga del Sur 11.4% of households say that armed groups influence when people can't fish much less with regards to the size of a fish catch And We found on the contrary a little evidence of popular support for the regulation of the fishing sector by armed actors It's only 4.6% in Zambuanga del Sur and 1.6% in Zambuanga Sibuge of Households who say that it's justified that armed groups would regulate fishing Nevertheless what we find is a clear presence of these armed groups interference in the form of taxation and five minutes and In the form of various forms of governance, so I just wanted to say something about where the I'm running late a little bit obviously So we also looked at the impact of the presence of these armed groups notably on the fish trade and on fish stocks This is more regression analysis with fixed effects and controls We found for example a negative impact on the fish trade and this is municipal fish trade So how municipal fisher folks sell their fish on the market and we find that? Households are more likely to sell at a loss or be forced to sell at a loss in those barangays Where there is the presence of these on groups and these are results of 14.8 percent and 12.6 percent That are statistically significant They also sell at a lower price in those barangays where there is the presence of these armed groups This is a negative effect also statistically significant so what this points to is forms of levies or Indirect taxation on the fishing sector on municipal fisher folk that is being enacted by these armed groups at the same time We were trying to get to this question of environmental protection and conservation So we looked at fish stocks and perceptions of fish stocks And what we find is that households are more likely to report that fish stocks have decreased over the last ten years in those Barangays where there is the presence of these on groups This is also a positive and statistically significant Effect of 13.3 percent So this is not an objective measure of fish fish stocks and environmental protection Yet it is an indication in as much as fisher folk actually know the waters in which they fish That there is an impact on the fish stocks of the presence of these on groups So very quickly about where we want to go from here So we want to consolidate the results on the environmental impact by bringing in other data sets We want to look at various forms of exchanges that might exist for these forms of levies or taxation by the on groups and Perhaps evidence of nascent form or existing forms of social contracts But more importantly what we want to get at is the mechanisms that mediate the impact of the its own groups on Fishing and fish stocks notably a political economy arguments via which basically The presence of these groups facilitates illegal and environmentally destructive fishing practices Such as dynamite fishing or the use of toxic chemicals and these types of things But more importantly this impact on collective action and communal management of fishing resources and here we have variables on social capital on trust on participation of fisher folk in Associations and we're trying to see whether that might be the mediating explanation of this impact of the presence of these groups on the environment So I just wanted to give a few broader policy implications so with regards to Mindanao itself Mindanao is still at a critical juncture of its history The peace process is both on track and in peril as a recent international crisis group reports has said There are threats tied to ongoing pockets of insecurity activism by on groups in certain areas underlying political dynamics of the peace process delays tied to COVID-19 which creates frustration among the stakeholders of this peace process and the fishing sector Importantly is really one of the key stakes and the ongoing negotiations particularly with regards to delimitation of municipal waters and taxation of industrial fishing But here I want to extrapolate a little bit and make some points about taxation in conflict affected areas First of all a very important but obvious but important point is that the social contract that's normally underpins state taxation is Severely challenged in zones of violent conflict I think that's really one thing that needs to be thought about in any type of taxation policy in relation to post-conflict context But also context of ongoing conflict Second of all there is an invisible tax burden on populations and on economic activity in those zones that we saw You know we have evidence of this tax burden to some extent that also needs to be taken into account in policy in relation to these To these regions There is also a durable implantation of the armed groups. We saw the social penetration of the armed groups This means that There can be various forms of support for these groups and implantation that can persist beyond formal peace or elite arrangements that end the conflict at a higher level But at the local level these arrangements and these forms of support and social implantation can persist and The durability of the protection and taxation Arrangements in is not just tied to the implantation of these groups It can also serve a purpose notably with regards to protection for example of fisherfolk So these are things that are very important to take into account in any type of policy that is related to zones of ongoing Conflict and post-conflict as well And finally a point about environmental protection and violent conflicts Alongside this hidden tax burden that exists in those zones where there is the presence and activism of these armed groups There is often a hidden toll on the environment, which is important Given the protracted nature of violent conflict and the fact that most zones of violent conflict today are Long-standing and show no signs of resolution There is really a question of you know how to protect the environment in regions that are not directly controlled by the state So, thank you very much


Maybe you've started getting acupuncture or even weirder, you've told your friends or family that you are seeing a Chinese medicine practitioner or a Chinese medicine doctor. And maybe their response was, isn't Chinese medicine a bunch of bull, or maybe they stated it as a fact. Or maybe they even said that they read a research paper that showed that acupuncture by itself is one big placebo. But it's helped you a lot. How do you respond? And what does all this really, really mean? And what is it really doing? What's up, you guys? Dr. Alex Hein, Doctor of Chinese Medicine and Licensed Acupuncturist. So before we jump into this video here today, there are two very important links right below it. The first is if you'd like to become a local patient of mine in Los Angeles or a telemedicine patient throughout California, the link to contact my private practice is right below this video. Now, the second link is for a free PDF download, which is four daily rituals that can potentially help you add years to your life with traditional Chinese medicine. So you can check those out right below this video here. So when your friends and your family think Chinese medicine is a bunch of bull, just remember this story. My mom had asked me when I was about to graduate what my title would be because she knew I was doing a doctorate. She didn't know really what doctorates in Chinese medicine are actually called. Now I told her it's I have a doctor in what technically what's called Oriental medicine, but they were trying to be inclusive of East Asian medicine, but it's a doctor of Chinese medicine. And my mom said, but if I tell my friends that you're a Chinese medicine doctor, it kind of sounds like voodoo or witchcraft. My thought was, well, if I just fixed your friend's problem that their Ivy League trained physician couldn't, then who cares what you call me. And it's clear that the mainstream media is really not trying to improve the reputation of Chinese medicine. I mean, one of the dominant narratives right now is that COVID came from a wet market in China that was consuming all these weird animals like bats. And they always throw in a little quip about Chinese medicine consuming weird animals, right? So the mainstream media is not really interested in the evidence on Chinese medicine. It's really interested in furthering the reputation of it being some superstitious bull that probably started COVID. Now the reality is maybe a little bit different. So let's talk about some of the prestigious institutions within the U.S. that have presented research and information on maybe more specifically acupuncture. That seems to be the most well studied in this country. And there is obviously reimbursement for it for many insurance companies. But let's talk about the big three in America. Harvard, Johns Hopkins, and Yale. These are the Kremlin Medical Institutions in our country and often throughout the world. They are some of the leaders, leading physicians, leading researchers. Now what's interesting is that each one of these universities has information and even research on Chinese medicine, including acupuncture, right on their very website. So Harvard, for example, says it offers acupuncture and even has studies listed on their website. Now one particular paper actually that they have listed right on their website describes studying acupuncture with these really cool fMRI studies. So they are actually testing what needling certain points. And if there is something to point location being a valid thing, can we verify that if you needle the spleen channel versus the stomach channel, does it really do something different that we can measure? And they are finding that with these fMRI studies, this kind of very active in the moment scan of the brain, we can see that that is true for many of the different points. That's very cool. That's on Harvard's website. Now the second being Yale. Now Yale School of Medicine has a publication listed on their website with the patients that have all benefited from getting acupuncture. And it says right on that article that it's, I don't know if it's a PR piece or a local news piece, but it's showing all these people saying how much it had helped them. The third is Johns Hopkins. Now Johns Hopkins has a whole list of conditions that may be benefited from acupuncture. Now, if these three organizations thought acupuncture and Chinese medicine was bullshit, why would they ever risk their reputation listing them on their website? Right? That's something worth considering. So if you have a skeptical friend or a skeptical family member, if what they want is research and evidence, there is research and evidence. And I try my best to publish it weekly on my website. If you go to alexhine.com, there's a weekly article with at least 10 citations per article on Chinese formulas and acupuncture. But let's talk about some other factors here. Now, your friends and your family, even though you may have said, this has helped me so much, it has helped me much more than my doctor or my specialist or the worldwide specialist. Why don't they take it seriously? Why don't my friends and family take it seriously? Let's talk about a couple of reasons. One is that they are a late adopter. Some people will never believe anything until the whole world believes it. The scientific establishment believes it has published front page news on it, etc. So some people are inherently late adopters. They're the last person to get the iPhone, the last person to try that new thing. They will always do what an old fashioned, trusted authority has done for the longest period of time. And that is really a psychological bias more than anything. And that's not something really you can fix. So it's worth understanding and worth remembering that some people just have that bias. The second reason is they haven't seen the evidence, which there is now. There's even more evidence for the use of Chinese herbs and herbal formulas because you can measure the biochemistry. So if you don't believe in biochemistry, then you don't really believe in anything that's scientific. So there is evidence now. The third real bias is that they don't really want to change. You know, some people may say things like, well, that works for you, but for me, I need this. You know, I need the antibiotics for my strep throat again. I need my antidepressant, I need my Xanax. I need this nasal drain. I need my mucinex, you know, whatever it is. When someone says, well, that may have worked for you, but for me, and this is often someone who's not really ready to heal. That's why if there is something that could possibly make you feel better, even if you don't believe in it, if it's not harmful, why would you not just try it? Right? So this is not a logical thing. This is an emotional thing and a psychological bias. Yet again, this is someone who's not open really to anything that could be used to heal themselves. There is some kind of resistance they have, and it's really not your problem to fix that, just as it's not my problem. If someone comes in, I'm going to do my best to help them. And if they don't believe it, it doesn't really matter. I can still help them. And I can only do what I can do. Now, I would say the fourth reason why some people don't believe in this is that they have other preconceived notions that are either cultural or religious or something with upbringing. So they have a, it has Chinese in the name, right? They have some beliefs about China and the Chinese and the wet markets and where COVID came from. They have some beliefs about China. So there's a, there's some prejudice or even some racism going on here. Maybe it sounds too woo-woo, right? Maybe the person they know that goes to get acupuncture is their crystal-wearing hippie friend that believes that if they put a crystal in their third eye, it's going to unlock their pineal gland and they'll see Jesus, right? I would be skeptical of Chinese medicine too if that was the person who wanted to refer me to go see an acupuncturist. But I think understanding that if this is something that can help someone and the resistance they have, whether it's psychological bias, emotional, they're not ready to heal, they don't like Chinese or China. They believe it's the devil's work. Understanding that they are missing out on potentially the most profound healing that may ever happen to them. And I mean healing in the sense of not ever needing medications ever again, permanent healing. So I think ultimately it's not really worth trying to convince friends and family, showing people how good you feel is probably the best proof after all, right? What do they say the best revenge is to be either really successful or really happy? I think just the evidence of your healing is probably the most effective sales pitch after all. So those are some of my thoughts on if your friends and family think acupuncture and Chinese medicine is a bunch of bull. Ultimately, if it's helping you, it's helped you more than anyone else had then who really cares what your friends and family think because you feel well again. All right guys, that's all I have for today. Again, if you want to become a patient of mine locally in Los Angeles or a virtually throughout California via telemedicine, the link below is to contact my private practice. There's also a free download there for you for daily rituals that can potentially help you add years to life with traditional Chinese medicine. That is also right below this video. Before you go, I have two other related videos for you here.


your growth, your development, often your healing and recovery more importantly, may be asking you not to save someone else from their disappointment, frustration, expectations at the expense of you, but for a change, to look after yourself. And if you have people in your world that keep putting you in a position to choose either between honoring yourself or relieving their discomfort, then you must learn to choose yourself because your own mental health and emotional health is at stake in many of these interactions that you have with people in your world who just want you to keep saying no to you so they keep getting a yes to them. It's time for you to get comfortable in saying yes to you even though it's no to them. It's gonna be okay. I learned this the hard way. Practice it a bit today.


Hello again, this is the next session of the course on nanoelectronic device fabrication and characterization and we have been discussing nanostructures and the formation on nanostructures. And last time we went on to discuss the formation of nanowires by the vapor liquid solid method and followed by the solution liquid solid method. We also pointed out that there are variations of these methods that use for example, lasers to assist the formation of nanowires. And then we went on to discuss the formation of nanowires and nanostructures in general by the solution process where the assistance of microwave radiation is used to obtain nanostructures of high quality much more rapidly by the microwave assisted method than by other methods. What we shall do this time is to discuss some general aspects of nanomaterial preparation and then go on to carbon nanostructures and thin films. We have already discussed aspects of heterogeneous nucleation which is where they come in the context of thin film deposition which are very important for nanotechnology in general, device fabrication in particular and then we will try to deal with physical vapor deposition, physical vapor deposition and atomic layer deposition. Now, some general comments we have discussed bottom up methods and mostly so far we have confined ourselves to the discussion of different chemical methods that are bottom up in their approach. It is useful to note that there are physical methods that are capable of producing nanoparticles and nanostructures as listed here vapor and gas condensation that is you have vapor which generally involves high kinetic energies and therefore correspondingly high temperatures and you suddenly subject them to cooling condensation. And if you do not allow that condensation to take place over a relatively long period of time that is if you quench it then in the absence of time for these atoms in this condensate to relax into crystallographic position proper positions you often get either nano crystals very small crystals or you get amorphous material. Jet pyrolysis is really much the same you have jet a jet of particles moving at a high speed which means high kinetic energy and high temperature and then you suddenly cool it to obtain a condensate that would contain nano crystals or even amorphous materials as I just mentioned. The quenching of metal alloys to obtain glassy metallic materials known as met glass which is actually an important part of technology for important part of materials technology that is a physical method where one obtains nano structure material through quenching. Thermal evaporation we have discussed evaporation condensation again thermal evaporation of let us say metals or metal oxides or some such material in a vacuum system which is often the way to produce thin films of these materials. Suppose you collect these evaporants including metals on a cold substrates normally this is done on substrates that is at room temperature in a high vacuum one evaporates material and collects it on a substrate often held at room temperature. But suppose you deliberately cool the substrate then again these particles that are full of kinetic energy and therefore correspondingly high temperature they get quenched and usually get thin films now with nano structured material. Laser evaporation is also the same thing lasers pump in a huge amount of energy into the target at which they are aimed and therefore there is instantaneous evaporation of the top layer of the material when it is bombarded by the laser and if one collects these material and one collects it on a substrate that is not heated then once again one can get nano structured material or even when it is heated even when the substrate on which this laser evaporated material is collected is heated even so it is possible to obtain nano structured material indeed an important part of thin film technology a physical method of deposition of thin films known as pulsed laser deposition PLD is based on this laser evaporation technique. Now most of these techniques that are listed here except really that of the technology of matte glass they are of low yield so you do not get much nano structured material given the amount of material one starts with. They may require elevated temperatures subsequently to obtain useful nano structured material and often involve costly apparatus for synthesis. But all of these constitute physical methods that are bottom up in nature one of the things to remember which I am not sure that I alluded to earlier is that nano structured material nano crystalline material that is whether it is formed by a physical method or a chemical method as long as it is a bottom up method as opposed to a top down method where for example one uses a ball milling to cut down material to very small sizes in such cases as we mentioned at that time defects are induced. But if you consider nano crystals of dimensions of the order of a few nanometers produced by let us say the solution based methods as in the case of metals or in the case of compound semiconductors the sol gel method and so on which we refer to or even the microwave assisted solution based processing. In all these methods the crystals that are produced are of very high quality which means technically that they have a low density of defects and that is in a way natural if you think about how atoms are progressively assembled into a periodic array. If the array is large very large let us say you are talking about a crystal of the order of a you know let us say a centimeter in size containing our number of atoms then as the assembly process proceeds as the atoms come together to form such a macroscopic crystal the chances of defect formation such as dislocations that is atoms in the wrong place wrong crystallographic phase. So, the chances of defect formation are increased when the total number of atoms that are assembled together is increased. So, in a crystal that has around the Avogadro number of atoms then naturally the chances of formation of defects is much greater than in the case of a nano crystal which might have let us say 10000 or 50000 atoms. So, in general given the scale of these crystals they have few defects much fewer therefore nano crystals are generally more perfect than macroscopic crystals of the same material and that is important to keep in mind because it has consequences we will come back to that. We come to carbon nanostructures carbon is a truly unique material as you know in terms of its chemical reactivity and ability to form compounds with virtually every element on the periodic table. Even so it has been even even the even though it has been known for a very long time carbon has really thrown as surprises in the recent decades with the discovery of bucky balls carbon 60 carbon 70 carbon 80 and so on carbon nanotubes soon thereafter and more recently the discovery of graphene a truly two dimensional carbon structure all of these are showing up to be very important technologically and certainly of course there has been a very considerable amount of new science that has come out of these carbon structures carbon nanostructures. Fullerians first C 60 C 70 and polymer forms I mean polymorphs I should say polymorphs of C 80 one in a so called rugby ball configuration the other one in a Nicosahedron configuration. These are all molecules of carbon with their respective number of atoms so these are macromolecules of carbon and these have been investigated for example C 60 has had the surprising property that if there is a metal that sits at the center of this or within this C 60 shell then it becomes a superconductor and so forth. Carbon nanotubes really have been much more relevant technologically speaking and these were discovered rather soon after carbon the bucky balls in 1991 and these have unique material properties and they are in if it is a single walled carbon nanotube because one can also have multi walled tubes as shown in this cartoon you know the one here is a multi walled tube you have concentric tubes whereas you have in the center a an array of single walled nanotubes if it is a multi single walled carbon nanotube as in the center over here then it is as nearly a one dimensional structure as one can practically have with diameters that can be as small as about a nanometer. Some features of these carbon nanotubes is that you know mechanically it is stronger than steel multiple tubes can slide inside of each other with the minimal effects of friction. So, it can be a very good lubricant material it can support electric currents of density 1000 times greater than silver or copper and surprisingly it can have properties ranging from that of a metal to those of a semiconductor based on the configuration of the carbon nanotubes. So, these are some of the unique features of carbon nanotubes which are as I said especially if the single walled then you have a nearly one dimensional structure. Now what is shown as left here is the hexagonal graphene template this is the so called sp2 bonded carbon that sits at each of these vertices of hexagons over here and what is shown on the right are three different configurations of carbon nanotubes that can be generated by folding this graphene sheet this is actually the so called graphene sheet that is graphene is a single layer a single two dimensional layer of carbon. In fact graphene is obtained by literally peeling off layers of graphite with a adhesive tape for example there is a physical method of producing a graphene sheet. So, what is this this is a graphene sheet and by folding the graphene sheet along different directions with respect to the position of the atoms in this hexagonal lattice as shown here one can get you know if the axis of folding runs through the atoms then one gets this arm chair structure of carbon nanotube which is closed at this end for example one generally wants to think of carbon nanotubes which are closed at both ends. So, this end where it is closed easily half a bucky ball. So, depending on the axis around which the graphene sheet is folded you would get an arm chair configuration or a so called zigzag configuration or a chiral configuration which lacks mirror symmetry. So, you have different configurations of carbon that can be derived quite readily by folding it along different directions of this two dimensional lattice and one can describe these things in terms of the basis vectors a 1 and a 2 as shown here basis vectors which will allow you to translate from any spot in the lattice hexagonal lattice to any other in terms of integral numbers of a 1 and a 2. The remarkable thing is that carbon nanotubes of the metallic type or rather of the arm chair configuration or metallic in character whereas, the other two configurations are semiconducting in character. So, it turns out that if one produces single walled carbon nanotubes if one manages to produce them then about one third of them would be of the arm chair configuration and therefore, metallic and the rest would be semiconducting on the average. So, this is the remarkable property of carbon nanotubes that they can be of both the metallic and the semiconducting types depending on the weight they are folded. So, this is a further demonstration of the construction on nanotubes in terms of the primitive lattice vectors that I just described a 1 and a 2. So, as shown here you can have the zigzag configuration by folding it along the line that bisects opposite faces of this hexagon and then the arm chair I have described and anything in between gives you the chiral symmetry therefore, this is the way one constructs the carbon nanotubes and this is a further expansion of the same thing to tell us about the left handed and right handed versions because there is no mirror symmetry and that is the characteristic of folding the carbon nanotubes along a line that is between the arm chair configuration and the zigzag configuration. A great deal of work has been done on these things and these are now really textbook material. I mentioned that you can have semiconducting carbon nanotubes in the zigzag and the chiral configurations what is shown here is the energy band gap semiconducts have energy band gap. So, this is the energy band gap as a function of the inverse diameter. So, we are talking about the diameter is increasing this way because this is the inverse diameter. So, as the diameter is increased from low values to higher values the energy gap falls from about 1.2 and approaches to 0 approaches 0 as the diameter of the carbon nanotube is increased. What it really means in terms of this folding is that if you have a for this vector for example, n 1 and n 2 if n 1 and n 2 are large relatively large then you would have a relatively large diameter carbon nanotube because you are folding it with many more unit cells in them. Therefore, that will have a larger diameter and those ones with the larger diameter usually have a smaller energy band gap. One of the earliest methods by which carbon nanotubes were grown is the laser assisted growth method. What is done here is to take a graphite piece in which either cobalt or nickel particles are embedded small particles preferably nanoparticles of cobalt and nickel are embedded in this graphite piece and this graphite piece is then bombarded with lasers. Remembering that the graphite piece itself is at a high temperature in a furnace and bombarded by this laser beam then the graphite is evaporated and then this evaporated graphite material is carried by the argon that is flowing through it as the carrier gas. So, this vapor of graphite that is evaporated is carried by the argon gas and it is condensed on a water cooled copper collector. So, it is a rather simple method direct method of a physical kind. When this process is conducted then it turns out that the copper collector collects single walled carbon nanotubes and it turns out that cobalt and nickel catalyze the formation of carbon nanotubes from this evaporated graphite material. So, this is a an early method of producing carbon nanotubes single walled carbon nanotubes. Subsequently chemical vapor deposition chemical methods such as CBD were developed to produce carbon nanotubes typically using a gas like methane as the precursor gas and it turns out that a catalyst such as cobalt, nickel or iron is required to catalyze the formation of carbon nanotubes from the decomposition of methane and the carbon that is obtained from that is then catalyzed into carbon nanotubes by these tiny particles of metals that are present. For example, on a substrate you can grow nano wires or rather nano tubes of carbon by spreading nickel or cobalt or iron particles on let us say silicon substrate which is heated to a high temperature and methane gas for example is then made to flow over that one. So, this is the general methodology it turns out that what is seen here is the two dimensional graphite lattice which is actually the graphene sheet. It turns out that graphene single walled carbon nanotubes, multi walled carbon nanotubes all of these can be produced by essentially the same chemical vapor deposition method using a variety of precursors that is it is possible to employ methane, acetylene, benzene, ethyl alcohol, carbon monoxide, ferrocene and so on a variety whole variety of carbon containing vaporous compounds and then by slightly altering the methodology for decomposition and catalysis of these things into carbon nanotubes it is possible to get carbon nanotubes, multi walled single walled and so forth by the general CVD method which works at around 700 to 800 degree Celsius. This is actually a piece of apparatus a chemical vapor deposition reactor thermal CVD that is only temperature is used to conduct the reaction as opposed to anything like a plasma CVD where a plasma is employed to accelerate the process typically. So, in this furnace one places a substrate and then uses a gas for example here ethylene C 2 H 4 hydrogen and argon. So, there are certain protocols over here that allows you to deposit carbon nanotubes on a substrate like silicon at a temperature of about 700 degree Celsius. The formation of carbon nanotubes by thermal CVD is really quite analogous to the vapor liquid solid method that we discussed earlier except that this is not really of there is no liquid formation. What happens is that in the metal particles that we mentioned cobalt decolor iron iron is really most effective. So, this metal particle acts as the substrate on which the surface on which the impinging hydrocarbon decomposes to produce carbon elemental carbon that carbon dissolves in the metal without the metal itself becoming liquid. And the dissolved carbon then emerges emerges as a carbon nanotube and the carbon nanotube grows out of this metal deposit. So, in practice something like this is done one takes ferric nitrate and decomposes ferric nitrate to give iron particles on a substrate like that of silicon that is kept inside the furnace.  And then one goes through the process of chemical vapor deposition using an appropriate hydrocarbon and as a result of it typically at about 700 degrees one gets the growth of carbon nanotubes by a process analogous to as I said the VLS process. It turns out that in such a system one can conduct these reactions under an applied electric field giving rise to carbon nanotubes that are essentially perpendicular to the substrate. So, you can have a well organized array of carbon nanotubes going on a silicon substrate by having an applied electric field during the deposition process. So, what is shown on the left here is an array of carbon nanotubes produced by the process that was just described. And what is shown here in the inset is the Raman spectrum of the carbon nanotubes that are obtained and it turns out that this particular signature this particular spectrum is the signature of single walled carbon nanotubes. The multi walled carbon nanotubes have a slightly different signature and therefore from the Raman spectrum it is possible to tell whether what you have got is single walled or multi walled carbon nanotubes through a CVD process. Now it turns out that depending on the flow rate of ethylene in the CVD process we described and the catalyst particle size that is employed in the process depending on that it is possible to obtain either single walled nanotubes or multi walled nanotubes. So, it is possible to control the nature of the carbon nanotubes that are obtained by tinkering with the process in a predictable manner as a matter of fact. So, what is shown here is a forest of multi walled carbon nanotubes that are obtained in the same chamber that was shown earlier in the same chamber by greatly increasing the ethylene concentration that is the precursor to carbon nanotubes by increasing the ethylene concentration it is possible to obtain a forest of multi walled carbon nanotubes. What is shown here is a diagram that tells us how for example, using a catalyst metal catalyst which could be nickel, cobalt or iron into which carbon of various types dissolve. For example, carbon atoms in the gas, carbon molecules in the gas, amorphous carbon, bucky balls all these things can go into the metal particle at an elevated temperature and then come out of this as carbon nanotubes under appropriate conditions. So, this really is sort of a devouring of carbon different kinds of carbon to yield carbon nanotubes what is noteworthy is that if one had bucky balls for example, then by a relatively small expenditure of energy 0.045 electron volts it is possible to fold it into a carbon nanotube fold the carbon into a carbon nanotube whereas, the energy required for doing the same thing with atoms in the gas is much greater several electron volts. So, if you had free carbon atoms then a great deal of expenditure of energy is required to produce carbon nanotubes from such disordered carbon. What is shown here is how the C V D process allows you to grow carbon nanotubes around let us say a glass fiber in this case. So, what is in the center is a glass fiber and you know all around that as shown in this magnified photograph carbon nanotubes have grown essentially perpendicular to the to the glass fiber surface. So, locally perpendicular. So, these things are done now quite can be done quite routinely quite predictably by the chemical vapor deposition process. What is shown here is how the process of C V D whether it is thermal or whether it is plasma assisted can alter the topology of the carbon nanotubes. So, what is shown here is that initially this process is conducted as a thermal C V D process that is only temperature is used to conduct the chemical reactions that result in the formation of carbon nanotubes. Subsequently as plasma is turned on now plasma C V D being a more rapid process would then pick it up and then allow you to grow this kind of a forest of nearly parallel carbon nanotubes at a pretty fast clip. So, there are ways in which therefore, one can alter the process to obtain carbon nanotubes structures by the way these carbon nanotubes can be as long as several hundred micrometers in length with a diameter of the order of 10 to 20 nanometers. So, the aspect ratio of these things can be very high. In fact, there are reports of how millimeter long carbon nanotubes can be obtained by suitably altering the process. So, far we have shown how using hydrocarbons carbon nanotubes can be obtained. What is shown here is how a different kind of a starting material in this case ferric acetylacetonate. I would like to recall to you that last time we used zinc acetylacetonate to produce zinc oxide nano rods from a solution under microwave bombardment. MOCVD stands for metal organic C V D. So, this is a metal organic compound with iron at the core of it and then methyl groups as terminations. Now, it turns out that this is a sublime in crystalline solid and one can employ this as a C V D precursor because it sublimes and produces vapor. When that is done in a rather simple C V D reactor where you have a high temperature over here for the substrate and then you vaporize the iron compound and you know carry it with argon vapor and so on. So, when this is done in an inert ambient that is argon and iron compound nothing else no oxygen and so forth. So, when it is in the ambient is inert then it turns out that depending on the pressure at which this reaction is conducted it turns out that it is possible to obtain carbon nanotubes as shown in the right hand micrograph simultaneously with iron oxide. So, what you get is carbon nanotubes that are interspersed with iron oxide in a composite material. Now, when the pressure is changed it turns out that this is now carbon nanotube rich. So, there is a smaller proportion of the oxide than of the carbon nanotubes. In other words by using a different starting material altogether not a hydrocarbon it turns out that it is possible to obtain carbon nanotubes along with in this case an oxide to form a composite which can be a very interesting material. Now, here is the Raman spectrum and the Raman spectrum has signature of multivolt carbon nanotubes here and it also has a signature of iron oxide Fe3O4. Fe3O4 are these particles that are seen here. So, you have the simultaneous formation of Fe3O4 and multivolt carbon nanotubes by this kind of a process. We move on to a somewhat general discussion of thin film deposition because thin film formation is an important part of device technology including nano device technology. There are physical methods and there are chemical methods. We have just now gone through the chemical vapor deposition process. So, there are numerous methods like sputtering and plasma enhanced material methods iron beam deposition and so on. Now, there are PVD and CVD methods with advantages for CVD over PVD and PVD over CVD. Now, one general feature is that in physical vapor deposition you have for example, in sputtering a target from which material is knocked out by bombarding ions like organ ions and those particles of target material that are shot out of the target collect on the substrate to form a film. So, this is the a physical vapor deposition method where the material that forms the target becomes the material that forms the film. In the chemical vapor deposition process you have some vaporous material including gases that flow through the reactor as we have shown in the case of the carbon nanotubes and they react on the hot substrate surface and produce film of the material that is the result of the chemical reaction. So, the material that is deposited is different from the material of which the vapors are allowed into the chamber whereas here the material of the film is the same as the material of the target. One of the important features of chemical vapor deposition is conformal deposition that is if you have contours on the substrate which of course is a very important part of semiconductor fabrication then chemical vapor deposition is capable of conformally covering that contour on the substrate that usually a patterned contour that is you can have conformal coverage of all these features that are produced by patterning. Whereas in physical vapor deposition because it is a line of sight process you have direct deposition proper deposition on these surfaces that are normal to the flow of the vapor whereas on these walls that are parallel to the flow of the vapor you can have little or no deposition. So, it is not conformal coverage in the case of physical vapor deposition and as you well know from the earlier part of the course you need conformal deposition in order to be able to cover features in devices which are constantly becoming smaller. These are examples of where for example you know here you have a high aspect ratio whole that you have to fill with a material and chemical vapor deposition turns out to be capable of doing so which normally physical vapor deposition processes are not capable of doing. So, C V D has advantages of uniform deposition over large areas and as we just said conformal coverage and usually high rates of deposition and so on and therefore it is often the process of choice for VLSI fabrication especially where highest high aspect ratios are involved. There are various kinds of C V D processes thermal and row pressure and so forth high pressure and all that. Now the chemical vapor deposition process can be of various kinds can have different kinds of reaction here is a decomposition of silane into silicon tungsten fluoride is reduced by hydrogen into tungsten which is again an important part of the tungsten plug process in VLSI fabrication. Silane is oxidized into SiO2 and so forth. Now all these are reactions that occur on hot substrates and the temperatures required depend on the kind of reaction. So, it can vary from a couple of hundred degrees to several hundred degrees and each of these is a case of heterogeneous nucleation. So, that reaction has to take place on the substrate surface and then of course as we discussed in the other the other day regarding the formation of regarding heterogeneous nucleation much the same kind of a process is required. So, you have the diffusion of reactants and then the adsorption of reactants on the substrate surface, reaction taking place and then the mobility of the react the growth species on the substrate to form this film through nucleation and growth and then the ejection of reaction by products into the chamber so that they are pumped out and so on. Therefore, just as in the case of a physical heterogeneous nucleation process which we discussed a couple of days ago this one also is a complex process that involves multiple steps. One thing to remember in the context of nanomaterials is that this process can be slowed down by controlling the substrate temperature as long as the substrate temperature is high enough for the reaction to take place. If the substrate temperature is not high enough to allow the reaction to take place of course then there is no nucleation. But usually these reactions take place over a range of temperatures and therefore it would be possible to lower the temperature in order to get smaller crystals that are generated out of this heterogeneous nucleation process. So, one way to obtain a nanostructured thin films is to lower the temperature of growth in a CBD process as long as I said as long as the reaction takes place at that temperature. Another way is to choose the reactants appropriately. What I have shown here is you know there are numerous ways in which for example one can obtain silicon this is trichlorosilane. You can have as I showed in previous you can have silane directly silane directly giving a silicon you can have trichlorosilane giving a silicon. It is possible to alter these reactants so that it allows us to alter the range of temperatures or the conditions over which the reaction thing can take place and that way to control the structure the microstructure or the nanostructure of the resulting film. Now, epitaxial growth of gallium arsenide. Gallium arsenide is a direct banded semiconductor and we mentioned gallium arsenide and gallium aluminum arsenide in the context of formation of quantum wells for the formation of lasers for example.  We mentioned thicknesses of the order of 1 or 2 nanometers so they actually nanostructured in that sense. So, epitaxial growth of gallium arsenide is possible by the CVD process by using trimethyl gallium and arsine to obtain gallium arsenide typically at about 600 degree Celsius. So, one gets high quality crystalline layers of a controlled small thickness through such a process. So, this epitaxial growth is actually an important part of nanostructured materials because these processes can be controlled with great precision to obtain let us say precisely 10.4 nanometers of thickness of gallium arsenide for example. CVD is versatile a whole host of materials this can be deposited by the chemical vapor deposition process elemental semiconductors compound semiconductors oxides nitrides and so forth. All of these can be the microstructure of all of these things or should I say the nanostructure of all these things can be controlled by the controlling of the by the choosing of the parameters of the CVD reaction. For example, micro crystalline silicon is an important part of technology under development. So, it is possible to obtain by the same CVD process not only single crystal silicon as shown here, but also micro crystalline silicon by choosing the appropriate conditions actually micro crystalline is generally speaking of nano crystalline dimension nanometric dimension. So, nanostructures of a whole host of materials can be obtained in film form by the CVD process. The CVD process has various parameters which we control as I was just saying flow rates deposition pressure temperature and the precursors themselves as I said there is usually a choice of these precursors. So, by choosing them one can choose the conditions under which the reaction takes place which influences the structure of these materials the crystalline structure of these materials. Therefore, all these give handles on obtaining film material by the CVD process with a highly controlled set of structures possible a whole host of precursors are there and so forth. So, you know this is a kind of a laundry list of different precursors inorganic precursors. The point is that one should have volatile materials as precursors that goes without saying because this is a chemical vapor deposition process. So, silane is really a gas at room temperature tungsten hexafluoride is a gas at room temperature titanium tetrachloride is a liquid at room temperature, but all of these have substantial vapor pressures which allow us to use them as precursor materials for CVD. So, these are all different precursors and one of the things I mentioned is the formation of gallium aluminum arsenide usually in epitaxial structures of nanometric dimensions that is just obtained by having an appropriate proportion of the gallium precursor with this which is trimethyl gallium, aluminum precursor which is trimethyl aluminum and then having the reaction with or seen at about 6 to 700 degrees to give us gallium aluminum arsenide of the chosen or desired composition. Similarly, nitrides which are now of course of great technological importance in the context of blue and green sources of light ferrocene is another precursor that is been employed for the CVD of carbon nanotubes. This you know TOS tetraethoxy ortho silicate is widely employed in semiconductor technology to produce SiO 2. I mentioned metal organic CVD which is again a particular process of CVD particular version of CVD where metal organic precursors are used such as the acetyl acetonates and so forth that would give films of metals and metal oxides including complex metal oxides as listed here it is a versatile process. CVD is a complex process because transport phenomena are involved because gases are flowing vapours are flowing. There is a whole variety of chemistry and often reactions in the gas phase may occur. So, the design of reactors and the geometry of reactors and so on are quite important for the successful execution of chemical vapour deposition to obtain the kind of material that one wants. So, there are thermodynamic factors because there are chemical reactions involved hydrodynamic factors because there is flow of gases and vapours involved kinetics involved both because of flow rates as well as because of temperature and the nature of precursors and so forth. CVD is a complex process, but fortunately it is possible to control it well model it also to obtain materials of the sort that one wants including very specifically nanostructured material. This describes the effect of temperature in an Arrhenius plot how the deposition rate of films in a CVD process varies with temperature. Therefore, you have because it is an Arrhenius plot you have inverse temperature. So, we are talking about low temperature here and high temperature on the left over here. So, as the temperature is increased the growth rate increases linearly in this region over here. So, this is the kinetic region at a middle range of temperatures because the growth rate is essentially independent of temperature. So, this is the region where one would like to operate the CVD process where the growth rate is relatively insensitive to temperature. This is how the concentration of the reactant the vapour pressure of the reactant affects the CVD process. So, again over here where nucleation in the gas phase occurs this is the region to avoid for the CVD process one operates in this region where the deposition rate depends on the concentration of the reactant in a linear fashion. So, since the concentration of the reactant can be controlled quite well one operates along this region to get the deposition rate one wants in a given process. Different types of reactors and the involvement hydrodynamics and the analysis of the hydrodynamics of the reactors to obtain what one wants and these are all of this is very important for the semiconductor industry and done with a great deal of care. Again flow patterns and the visualization of flow. So, that one can design these things properly to obtain uniform films and so forth. Different kinds of configurations to obtain multi multi substrate reactor over here and so forth. So, these are all different versions of the reactor to obtain CVD films. This again a demonstration of the capability of CVD to provide us with conformal coverage. Now, so far we have dealt with CVD in the context of high technology applications, but CVD is also obtained or used to obtain cutting tool coatings for the machine shop actually. So, it turns out CVD is very effective in obtaining multi layer coatings of aluminum oxide and carbide and nitride and so forth to enhance the tool life in cutting tool operations. So, CVD is used in such a much more mundane process as well. We will conclude there for today. So, what you have dealt with today is to review some general aspects of nano materials by the physical method by physical methods and then we went on to discuss carbon nanostructures and how carbon nanostructure in particular carbon nanotubes and how carbon nanotube properties depend on the configuration of carbon nanotubes and the production of carbon nanotubes by the chemical vapor deposition process and then we went on to review the general aspects of chemical vapor deposition process and how it has advantages over the physical vapor deposition process and certain applications of the chemical vapor deposition process both in high technology and what we just mentioned at the end in mundane technology. We will continue with this discussion next time and then go on to discuss the analysis, the characterization of nano materials by different methods. Thank you.