Welcome to this NPTEL lectures on cryogenic engineering. I am Mellin Dutray, Professor in Department of Mechanical Engineering IIT Bombay and this is my first lecture on cryogenic engineering. Before I go into the details of what cryogenic engineering is all about, I just want to let you know what is cryogenics. Cryogenics is basically coming from the word cryo which means very cold. From Greek language this word has come and genics means to produce. So basically cryogenics means science and technology associated with generation of low temperature below 123 Kelvin. Now why this 123 Kelvin? We can study about that later in the next lecture. However, what you have to understand is till 123 Kelvin what you call is refrigeration and if I want to achieve temperatures below 123 Kelvin what we call is cryogenic engineering or cryogenics. This course aims at students who are interested to study the science and technology of low temperature. Basically cryogenics is generation of low temperature. What is the science behind generation of this low temperature? What is the technology to achieve this low temperatures? This is all we are going to study in cryogenic engineering. The purpose of this course is to give introductory knowledge of cryogenic engineering. This is a course which normally we will aim at the PG level students or the final year undergraduate students having good background of various subjects and this course is meant for them. The course is both theoretical as well as mathematical. I am sure it will engross the students. This course will interest students who want to take career in cryogenic engineering. We know that cryogenic engineering is very widely used in space and atomic energy and things like that. I am sure lot of students will get motivated from this course in order to take their research career in cryogenic engineering. The prerequisites of this course are engineering mathematics, heat transfer, thermodynamics, refrigeration. Those who have done this course which possibly can happen at the final year undergraduate learning or in the post graduates or ME or M Tech, I am sure those students will definitely appreciate this course. The points to remember while doing this course are each lecture presentation ends with a self assessment test based on the particular lecture. So, after each lecture or after a few lectures, we will have self assessment test where the student can assess himself or herself. The best knowledge is gained when the student solve the self assessment test very honestly and with proper understanding. So, we believe in that whatever assessment, self assessment is to be done at the end of each lecture or after a few lectures. We feel that the student should take this test very seriously. At the end of the lecture, when he or she does this assessment, when they follow that a particular thing has been followed or not, will be visible to themselves when they do self assessment. So, we expect that the students will do this very, very honestly. A greater insight into the subjects can be obtained by referring to the books specified. We are specifying some books for extra reading, for more general reading, for more special reading also and we believe that this students will have hands on these books. They will go through these books and get some extra knowledge. Assignments are included wherever necessary in order to have clear understanding of concepts. We believe that whatever knowledge one gains out of this course, we have to do some assignments wherein lot of fundamentals get cleared. A lot of mathematical problems will be there. Some theory could be there. It will be clear only when you do these assignments very honestly. Before each assignment an example tutorial problem will be solved with a detailed explanation. So, depending on the kind of assignment you want to solve, we will take a tutorial here. We will solve the problem step by step. We will see to it that when follows all the steps involved in those tutorials, in this example or assignment problems and after that we expect that the student will go through all the assignments honestly and come to an answer. Answers also will be given at the end of these lectures. The best knowledge is gained when the students solve the assignment problems honestly and with proper understanding of concept. I am sure you are clear with this. Now, there are various books available on cryogenic engineering. I am giving you some references here so that while doing this course, you may follow some extra reading with these books. The important book is by Randall Barron on cryogenic systems available from Oxford University Press and the last edition available is of 1985. This gives in summary on most of the topics I am going to cover in this course in short, however, but then it will touch up on all the points. For some specialized reading, you will have to go to specialized books or journals. Then a book by Tim Haraus and Fleen on cryogenic process engineering by Plenum Press also is available. It is also a good reading for cryogenic engineering. Cryogenics also goes with vacuum and therefore, I have given here a book by Pipcov on fundamentals of vacuum engineering where some fundamentals of vacuum which are necessary from cryogenic engineering perspective are given in this book. The next book is Thomas Fleen. The book is cryogenic engineering. The second edition is available as late as 2005. It is an interesting reading and a lot of problems assignments could be taken up from this particular book. Then we have got cryocoolers. I am going to talk about cryocoolers for about six or seven lectures and we have got books on cryocoolers part one and part two by Walker. The very famous books, in fact, possibly these are the only two books on cryocoolers as per and this also will give you some basic understandings on different cryocoolers including pulse tip coolers, sterling coolers. In addition to the books which I just talked about, we have got various proceedings of the conferences that also gives a very interesting results related to contemporary research happening in the world. For which we propose the proceedings of advances in cryogenic engineering, the proceedings of international cryocooler conference, proceedings of ICEC or international cryogenic engineering conference or ICMC which is international cryogenics materials conference. In addition to these conference proceedings, what we have is cryogenic journal and what we have in addition to this is Indian journal of cryogenics. Cryogenic journal is published almost every month. It is a very prestigious journal. To get paper in this journal is also supposedly very prestigious. In addition to that, we have conferences alternate year in India which are called national symposiums on cryogenics and many times the papers which we present at this conference in the national symposium are also becoming part of Indian journal of cryogenics and that also can give you a perspective of what kind of research is being carried out in India or elsewhere. So, all these books in addition to the proceedings which I gave you and the journals will form a very interesting and important reading as far as cryogenic engineering is considered. With this background, I will now talk about what I am going to teach in this course. So, what is the syllabus for this course? The course syllabus is as follows. Now, this course I am going to give under different topics and there will be around 12 topics and under each topic, I will give you one or two or five or say one kind of lectures depending on the scope of that particular topic. For example, the first topic or today's lecture is on introduction to cryogenics and its application. Today's lecture, I am going to cover the topic number one which is introduction to cryogenics and its application. The next topic is properties of cryogenic fluids. Now, there are different cryogenic fluids or they are called as cryogens also. For example, we have got liquid nitrogen, liquid helium, liquid hydrogen, liquid neon, liquid oxygen, etcetera. All these are normally called as cryogens and they have got very specific properties associated with them. For example, liquid nitrogen has got its own properties like what it is boiling point, what it is a density, what is the latent heat of it. All these form a very important characteristics of liquid nitrogen. For example, liquid oxygen, liquid oxygen has a boiling point of 90 Kelvin. It has got its own density. Liquid helium has a boiling point of 4.2 Kelvin. So, there are various important properties associated with these cryogens or cryogenic fluid. Now, depending on the end use of this cryogenic fluid or the requirement of the cryogenic fluid, you will select a cryogen. If I want to get a temperature of 77 Kelvin, I will choose liquid nitrogen. If I want to use oxygen, then I will use liquid oxygen. If I want to go below very low temperature, in that case I will go for liquid helium, which gives me 4.2 Kelvin. So, these properties are very important data in order to decide what is the cooling effect I am going to get from this particular cryogen. Depending on the density, depending on its latent part, latent heat, I have to select a particular cryogen and therefore, it is very important to study the properties of these cryogens or these cryogenic fluids. So, this will cover in the next topic and under this topic possibly we will have two or three lectures covering different important cryogens. One of the most important parts for cryogenic engineering is the properties of material at cryogenic temperature. The materials are very, very important and you cannot use all the materials in cryogenics. One can use only specific materials at very low temperature. It will be understood. I will show a demo sometime from now, how the material properties change at low temperature. So, there are different material for example, stainless steel, copper, carbon steel, aluminum, the properties of these materials change drastically at low temperature. This is a very important property. For example, specific heat capacity, what happened to its shrinkage, the material shrinks at very low temperature. What happens to this property? What happens to its conductivity? What happens to its ductility? These are very important properties and this will study in detail in the topic called properties of materials at cryogenic temperature. Now, here I would like to conduct a small experiment to show you cryogen that is liquid nitrogen and I will show some material that are available with me right now and you can have a look at this experiment. I am sure you will get lot of knowledge after seeing this experiment. So, let us see the liquid nitrogen because you must not have seen liquid nitrogen. So, what you see here in this video is a liquid nitrogen container which is around 1 to 1.5 liter. So, here you can see that this is a specially made container which has got special insulation capacity and what you can see also on this person is basically some safety devices because you cannot touch liquid nitrogen directly. Also, you should not be able to see, you should not see the fumes which come as soon as liquid nitrogen exposed to atmosphere. So, one has to be very careful about the safety that has to be taken into consideration while having a cryogenic experimentation. In fact, you will refer to my last lecture in this lectures which basically addresses the point related to safety in cryogenics. Now, what we will do? This has around 1 liter of liquid nitrogen. I will put this liquid nitrogen into this container which is a thermocool container and let us then put some devices like some materials like a rubber or potato and see what happens to the property, the simple properties of these materials as soon as they are put or they are subjected to cryogenic condition. So, let us see while we transfer liquid nitrogen have a look at how the liquid nitrogen looks and how it boils off immediately when it is put to the atmosphere. So, you can see the boil of fumes and you can see the liquid nitrogen is like water actually you know except that this is starts boiling immediately and the evaporation and the fumes are obviously there, they will always be there. Please note the safety devices again. So, here are two materials one is a simple flexible rubber you can see alright quite elastic in nature and we will put this rubber in the liquid nitrogen also we have got a potato. You know potato has got lot of water and as soon as we put this potato and the rubber the properties will change. So, let us put this two materials for let us say one or two minutes and you can see that suddenly evaporation has increased. You can see how vigorous the boiling is right. You can see the evaporation happening, you can see the fumes coming out of this and you can see now how boiling is happening now. It has become still now, but you can still see the bubbles over there. It is getting settled now basically and you can see some cracks having appeared over here right now only. Now, let us take out this rubber and let us see what happens to its properties and you can see that it is not standing, it is standing like a very strong object and you can see now it has actually become very very hard. It is no more flexible, it can be broken into pieces, it can in fact it can be crushed now. It has become as hard as knife also and let us see potato and potato. One can do the powdering of potato, it has become as hard as a stone and one can actually make a powder out of this potato. So, you can see what has happened to these materials as soon as they were subjected to cooling, they were subjected to cryogenic conditions and you can see these parts. In fact now this rubber also can be powdered, the potato also can be powdered if they are crushed by some hard device hard rock and this is what happens, this is what shows what happens to these materials when they are subjected to very very low temperature. This shows obviously that as soon as engineering materials also when they are subjected to low temperature the properties change. The first topic is gas, liquefaction and refrigeration system. Now liquid nitrogen, liquid oxygen or liquid helium they become liquid only when you cool the gas for example, when you cool nitrogen gas slowly from room temperature to its boiling point then what you get is liquid nitrogen. But what is important to understand is how to reduce this gas temperature from 300 Kelvin to its boiling point. This is very important thing for which you have to apply various technique like compression and expansion of gas the way we do in domestic refrigerator. In order to reach the lower and lower temperatures nearer to the boiling point of this gases for example, 77 Kelvin for nitrogen 4.2 Kelvin for helium and thing like that I have to device a system whereby I reduce the temperature of gas from room temperature to the boiling point of these gases and this is the most important thing. Not only that it is important that how do I do that thing but what is most important is how efficient I am doing because in order to achieve a particular temperature I can go by a process A or process B or process C. What is important for me to understand is which process is more efficient that means my work input should be as minimum as possible in order to reach the boiling point of this particular gases. I need not compress the gas to a very high pressure because the compressor work input is very high in those cases. This is what we will cover different gas liquefaction cycle and for a particular cryogen then we will have to select that this particular cycle is the best. Similarly, like liquefaction what we have is a refrigeration system also. These gases are ultimately utilized for giving cooling effect or the cold or the refrigeration effect. For example, when I take the latent heat from these gases at their boiling points what I get is a cooling effect at constant temperature. If I want to have I want to have a object which I want to cool it down to 77 Kelvin, 80 Kelvin, 50 Kelvin, 40 Kelvin, 4.2 Kelvin or 2 Kelvin. Accordingly, I will have to design the refrigeration system. For example, to have a superconducting magnet what I need to have a refrigeration system or a cooling system. So, this topic number 4 is a very important topic and a very broad topic. I may take around 6 to 7 lectures in order to cover the gas liquefaction and refrigeration system at lower temperatures. Having done this for industrial gases utilization what is most important is gas separation. As you know air is a mixture of various gases. If I want to get my hands on oxygen gas or nitrogen gas or neon, aragon, helium etc. ultimately I get it from air which is a mixture of various gases. I have to ultimately liquefy air which happens at 78 Kelvin around and from where I will have to separate all these gases. Now, because of the mixture this whole air as a mixture has got completed different properties because different gases will liquefy at different temperatures or they will condense at various temperature and what is important is to understand the phase diagram of this mixture. So, the gas separation will depend on the boiling points of different gases in a mixture. For example, I have got a mixture of nitrogen and oxygen or nitrogen and helium. I have got two different boiling points one for nitrogen one for oxygen or I have got a boiling point for nitrogen and helium which is 77 Kelvin and 4.2 Kelvin or 90 Kelvin for oxygen and 77 Kelvin for nitrogen. In order to separate out this mixture effectively in order to get pure gases from this I have to devise a gas separation system. Basically I have to understand how do I separate these gases? What should my work input be in these cases? This is normally done by fractional distillation, but then you have to devise or design a distillation column and this is the most important part of it. So, gas separation along with gas liquefaction or 4 and 5 topics are very important to study in cryogenic engineering. The next topic is cryocoolers and this also forms a very important topic of research. As I said earlier there is an international cryocooler conference which happens only to bring out the research work that is being done all over the world at one place. For example, at IIT Bombay also we have been doing a lot of work on cryocoolers and I will show now a simple cryocooler. What is a cryocooler? Cryocool is just a refrigerator which produces very low temperature in a close cycle manner. For example, I have got different types of cryocooler what is called as sterling cooler, what is called as Gifford-Mackamon cryocooler, what is called as pulse tube cryocooler. This is a cryocooler which is a sterling type cryocooler developed at IIT Bombay. What you can see here is this is a cryocooler and this part houses a compressor. In fact, it is called a linear compressor. It is a dry compressor there is no lubrication in this. So, this is a compressor and this is a expander. The way you see in domestic refrigerator you have got a compressor at the bottom of the refrigerator and you got a expander which is actually a capillary tube. Then you got different heat exchangers also. Similarly, in this cryocooler which is nothing but a refrigerator which produces very low temperature. This has also got a compressor. There houses a heat exchanger inside this and there is a expander at the top of this thing. Now, I will show you what it is here. What you can see at the top is the cold finger. This is called as cold finger and if I want to cool certain object I have to conductively couple that particular object to get connected with this cold finger. This cold finger is going to generate around 80 Kelvin temperature. For example, this cooler has been designed to produce around 0.5 watts at 80 Kelvin to cool some other object. So, in a closed cycle manner there is a gas which is helium in this case is continuously compressed and expanded in a closed cycle manner in order to produce 80 Kelvin temperature at this point. So, this is nothing but a closed cycle cooler which works on sterling cycle. That is why I call it sterling cooler. So, it is called a sterling cycle cooler producing around 0.5 watts at 80 Kelvin. In a very efficient design, if I want to carry a very efficient design of this cryocooler my power input to this compressor should be as minimum as possible. So, that the coefficient of performance or the COP is very very high. So, whole design analysis has to be carried out in order to understand or predict the performance of this cryocooler and then when I have to devise the dimensions of this cryocooler fabricated accordingly and see the experimental results for this cryocoolers. In this way we do sterling cycle cryocoolers, GM cryocoolers or Gifford Macmon cryocoolers or pulse tube cryocoolers and thing like that the various types of cryocoolers which one can design. The next topic is cryogenic insulation. As you know when I am going to talk about cryogenics, I am going to talk about very very low temperature and outside temperature of the ambient is 300 Kelvin which is very high temperature. So, the heat is going to rush from outside to inside which is what we do not want. Otherwise I want to cool a particular object but because of the leakage of heat ambient heat from outside my cooling effect will be nullified. In fact some of the cooling effect will be getting wasted as losses. So, in order to minimize that what is more important or what is most important is the insulation. Now insulation is a critical part of cryogenics and depending on the low temperature I am talking about. For example, if I am talking about 80 Kelvin or if I am talking about very low temperature of 4.2 Kelvin, I have got different types of insulation and these insulation are in different forms like pearlite powder. It could be vacuum insulation. Vacuum is a very important part in cryogenics and that is why my next topic is going to be vacuum. So, vacuum basically nullifies all the conduction and convection or it removes all the air around the colder part. If I do not do that thing, the moisture in that air will get frozen down. Therefore, I have to remove all the air around the cold finger and that is why vacuum insulation also is a very important part. I am going to show a very typical insulation here. What you can see is a very typical insulation and here this is called as multilayer insulation and it has got highly reflecting surface like aluminum, aluminum foil, aluminized mylar like that. So, we can have a very highly poly surface and we can have different layers of this. We can have different layers of this and each layer is separated by a non-conducting medium like nylon net. We can have some non-metallic stuff which is a nylon net or any other things we separate out and this is what is called as multilayer insulation. Now, this multilayer insulation is wrapped around. For example, this is a cold finger. I will wrap this multilayer insulation in a very typical manner and what is most important is how many layers are there. So, one has to have 10 layers or 20 layers or 30 layers that also one has to optimize depending on the temperature and heat in leak and also the vacuum around. So, multilayer insulation works only when there is a vacuum around it making effectively the thermal conductivity across this direction from outside to inside as minimum as possible. It could be 0.0001 conductivity could be of this order. So, the conductivity gets drastically reduced when multilayer insulation is there. So, if I want to reach very very low temperature, I have to use multilayer insulation in presence of vacuum in those cases. So, insulation is a very important part in cryogenic engineering. This has to be taken care of effectively depending on the end temperatures or the low temperatures we are going to be talking about 77 Kelvin or 4.2 Kelvin or 25 Kelvin. This will decide what insulation I am going to use. As I just said, vacuum technology is a very important part and vacuum is a very integral part of cryogenics. So, what is this vacuum? What are different types of vacuum? How do you get these vacuums? What are different vacuum pumps is also have to be studied in cryogenics. So, this part also will be covered in cryogenics while learning this topic. The next important part is instrumentation in cryogenics. You can understand instrumentation at room temperature and instrumentation at very low temperature has to be different. For example, if I want to carry out temperature measurement, pressure measurement or I have got different cryogenics kept in a cryostat and therefore, I should know how much liquid nitrogen is left there. So, what I call is a level measurement. I should know that it was 100 liters today. Tomorrow it could be 90 liters. Day after it could be 75 liter depending on the usage and depending on the losses. So, I have to measure in cryogenics the temperature, pressure, level, mass flow rates and whatever technique I devise at room temperature are not applicable at low temperature. One has to follow a different technique because the properties or the calibration is completely different at low temperature. For example, just for today's lecture, if I talk about measurement of temperature at very low temperature, for example, at 4.2 Kelvin or 10 Kelvin, what I use is something called as silicon diode.  This is a very small piece and this has been calibrated to measure temperatures up to 1 Kelvin. This is a very costly piece. If you get it calibrated, it is a very, very costly piece still. This is a diode at lower and lower temperature. The voltage or the resistance starts increasing and this is calibrated in terms of temperature at lower and lower temperature. In addition to this, what I have also is a Pt 100. This is called platinum 100 and what you can see from here is Pt 100 can measure the temperature up to 30 to 40 Kelvin. Let us say 50 Kelvin is better. From room temperature to 50 Kelvin, I can measure the temperature. When I say Pt 100, it has got 100 ohms resistance at 0 degree centigrade. So, these are the two things I can show. I can measure the temperature up to 50 Kelvin using Pt 100 and I can measure temperature up to 1 Kelvin using silicon diode. So, these two are very important temperature measuring sensors which are generally used in cryogenics. All right. So, one has to understand how do I measure temperature? What is the philosophy behind the temperature measurement in these cases? What are corresponding errors? How do I employ these things in the actual instrumentation and thing like that are very important aspects of cryogenic engineering instrumentation. And finally, what is most important cryogenics is safety. When has to observe certain norms, when has to use certain glows, we have to use goggles and thing like that. And why do I have to do all these things? Because you are working at very low temperature. If there is small accident, if the nitrogen in atmosphere increases or oxygen level drops down, you can suffer from some called as asphyxiation. And I will talk about all these things later in the chapter, very important chapter or topic on safety in cryogenics. These are different topics which I am going to cover in this syllabus. I will take several lectures under each topic in order to cover these. Now, after understanding what is covered in this, what I want to bring your attention to is what are different applications of cryogenics. Now, cryogenics has got different application in space, in mechanical engineering, in medicine, in superconductivity and thing like that. I am just going to show certain examples. I may not go into the details of each of those application because each of those applications are chapter by themselves. What I am going to go is to go through this slide. You might read that with me and I will just take you through this slide so that you get a glimpse of what those applications are of cryogenic engineering in this different special topics. For example, space. Under space, I got cryogenics in rocket propulsion, cooling of infrared sensors or space simulation. These are very important aspects of cryogenics used in space. Now, what are they? Cryogenics engines are powered by cryogenic propellants. You know different propellants are there, but if I use cryogenic propellant, for example, liquid hydrogen can be used as a fuel to propel the rocket. Most of you have heard about cryogenic engine and cryogenic engine uses liquid hydrogen as a fuel. It also uses liquid oxygen as an oxidizer. So, these two are important components. Liquid hydrogen is liquid at 20 Kelvin, liquid oxygen is liquid at 90 Kelvin. These two form the fuel for cryogenic engine and therefore, it can work as cryogenic propellant and these are very, very important. The next is cooling of infrared detectors or telescopes or cold probes or some of the major applications of cryogenics. I have to use infrared detector in space because when I am taking night surveillance, when I am taking picture, I have got infrared detectors. Now, in order to get a good signal to noise ratio, that means in order to get a good image, I have to have detector at very low temperature. In fact, lower the temperature of this detector is better in the picture or less is the noise and therefore, infrared detectors have to be kept cool at 80 Kelvin or less than that. As I said, lower the temperature, better it is. Similarly, I have got lot of electronic circuits in space. If I cool these circuits down, for example, amplifiers or any electronics, which gets heated over a period of time. If I have got cold probes, I can keep it very cold and therefore, the noise level will be minimum in this case. This form a very important application of cryogenics in space. In order to do that, what I do is normally develop miniature cryocooler which goes in space and the cold finger I just showed you earlier, sterling cooler for example, is very widely used to cool the infrared detector in space and what is important therefore, is to design a miniature version of sterling coolers, less weight and less volume, which are very important things for space. Space simulation chambers are realistic environment for spacecraft. The cold space is simulated at cryogenic temperature by use of ln 2 or liquid nitrogen.  What is space? Space has got very less temperature of around 4 Kelvin and very, very less pressure that is vacuum. All these things have to be simulated on the ground. If any part you want to take in space, it has to first gets space qualified, which will what is what will happen in space simulation chamber. It is a small, it is a small case which is done on the ground which simulates condition in a space, wherein the low temperatures are generated by different cryogenics like liquid nitrogen, liquid oxygen etcetera. At the same time, different levels of vacuum are required in space and what we do for this? We use cryo pumps or a turbomolecular pumps. In this way, we can achieve lower and lower vacuums to simulate condition like what it is in space. This is a very important applications of cryogenics in space. If I move away from space, I go to mechanical engineering now, wherein the applications of cryogenic engineering are in magnetic separation, heat treatment of different materials or recycling of certain materials. There are various applications, but I will touch upon only three of these aspects in this particular lecture. What is magnetic separation? The magnetic separation technique is used in variety of applications like enhancing the brightness of kaolin, this is the clay, improving the quality of ultra high purity quartz etcetera. What we use is a superconducting magnet ensures proper separation. So what I am doing is basically, when I get this kaolin clay from different ores or mines on the eastern part of India for example, it gets associated with lot of metals. And in order to separate these materials or metals like silicates etcetera, what I use? I pass the whole thing through some magnet and these materials or metals will get attracted towards this magnet. After that, the kaolin will be free of these metals. However, in order to separate out these materials from the kaolin clay, what I need is a very high magnetic fields and these high magnetic fields can be achieved only by superconducting magnets and not by electromagnets. If I were to use electromagnets, then my current passing through these wires will be very, very high and therefore, losses will be very high. So what I have to use for this is basically superconducting magnet. This is very widely used techniques. Superconducting magnets are meant for magnetic separation or very big magnets through with the kaolin passes and it comes out without these metals at the other end. Similarly, cryogenic heat treatment is given to lot of metals. As you go on cooling the object, for example, what we do in tempering and annealing is you first go to a very high temperature and start cooling the object and we stopped at ambient temperature. If I do not stop at ambient temperature and go below to cryogenic temperatures, there is something called as written austenite which will get converted to martensite and which is what we want. The written austenite is very, very brittle sometimes and therefore, I would like to have complete conversion of this austenite to martensite. And therefore, cryogenic treatment of very special metals is carried out and you get a better metal at the end of the heat treatment. What do you get at the end is the lives of the tools, die castings, their dies, forging, jigs and fixtures, etc. increase when subjected to cryogenic heat treatment. This is very important. The life of guitar string increases by 4 to 5 times with no need for tuning. So here you can see that the life increase is there because of cryogenic heat treatment carried out to liquid nitrogen temperatures. Cryogenic recycling turns the scrap into raw materials by subjecting it to cryogenic temperatures. There are certain materials like rubber or plastic which we want to scrap and it is not very easy to scrap these things. So, what you do? You expose this material to very low temperature. You put them in a liquid nitrogen bath. As soon as you do that thing, as we saw in the experiment, this material become very hard. It becomes very rock hard and then one can use some kind of press in order to crush. The whole scrap can be crushed like a metal in those cases and it will ultimately get converted to powder. It is very easy to scrap in the form of powder. So, if you have got a huge raw material, for example PVC, rubbers and plastics etc., you can give a cryogenic treatment to those things. You can give a cryogenic recycling treatment to those subjected to low temperature and crush it to powders. Various designs are available.  This forms a very important applications of cryogenics in mechanical engineering. Moving away from mechanical engineering to medicine, this again is a very important aspect of cryogenic engineering usage in medicine. One can use cryogenics in cryo surgery, cell preservation or food preservation. Preservation industry is huge as far as cryogenics is concerned. From the medical point of view, I will show you what its usages are. Cryo surgery is a novel technique in which the harmful tissues are destroyed by freezing them to cryogenic treatment. This surgery is carried out for various aspects. For example, dermatologists use this surgery just to remove unwanted moles or something like that on your body. Some treatment is given on your skin by doing a small surgery at very low temperature. Why? Cryo surgery has shorter hospital stay, less blood loss and small recovery time. This is a very important aspect. One can go in the morning and come back in the evening. That kind of cryo surgery are also possible, which is done at very low temperature. It is generally used in patients with localized prostate or kidney cancer, skin disorders, retinal problems, etc. This list is actually increasing with time. However, the data is keep coming. There are certain heart elements also that could be treated using cryogenic techniques. When it comes to preservation, the preserving food at low temperature is a well known technique. This is what we do in a domestic refrigerator. Cooling of seafood, meat, milk products, long time preservation is achieved using liquid nitrogen. Liquid nitrogen is very widely used for transporting seafood or meat or milk from a port A to port B. One can keep everything reserved in an original form frozen at cryogenic temperature. Therefore, it is a very important technique. A very massive work is being carried out as far as preservation of food using cryogenic techniques is considered. Systems are developed to preserve blood cells. This is again a usage in medicine. You can preserve blood cells, plasma cells, human organ and animal organs at cryogenic temperature. So, the preservation using liquid nitrogen bath to preserve blood cells, plasma cells, human cells, stem cells also is the latest addition to this list. This all thing is done at cryogenic temperature. Coming next from here to the gas industry. As you know, gas industry is basically the gases. The industrial gases is a very sort after. For example, oxygen, nitrogen are used, oxygen is used medical hospitals and therefore the gas industry is a very, very big industry and the gas industry therefore uses cryogenic techniques for liquefaction, separation and storage. The very important aspect of cryogenics, very important usage of cryogenic. The transportation of gases across the world is done in liquid state. One need not do the transportation of the gases in the gaseous form because if you want to do the transport of gases in gaseous form, the gases are compressed at a very high pressure, which is sometimes unsafe, which is not accepted sometimes. So, what you do? You convert those gases to liquid by lowering the temperature, by liquefying those gases using cryogenic techniques and this is done by storing the liquid at cryogenic temperature. If I get liquid of those particular gases, I can store those liquids at cryogenic temperature and in this way I can do transportation much easily as compared to those in case of gases. The use of inert gases in the welding industry has initiated higher demand for gas production in the recent past. Nitrogen, oxygen, all these things are very widely used in the industry and therefore these gases require cryogenic techniques to liquefy those gases and transport those gases and store those gases and this is a very high demand of gases for cryogenic gases like nitrogen, oxygen, neon, argon, etc. Cryogenic is like LOX, which is liquid oxygen. LH2, which is liquid hydrogen, are used in rocket propulsion as we have just seen earlier while liquid hydrogen is also being considered for automobile. You may know that lot of research is being carried out to use hydrogen as a fuel in an automobile. In fact, a car is already ready which uses liquid hydrogen like as a fuel like what we do in using petrol or diesel. So, here all these gases, all these liquefied gases play a very important role as they are needed to be consumed in these forms. Liquid nitrogen is used as pre-coolant in most of the cryogenic system. Whenever I want to do cooling, I have got liquid nitrogen as a very cost effective way which will reduce the temperature from room temperature to 77 Kelvin. As you know, nitrogen is available in air. So, nitrogen is freely available. One can say it is a very cost effective solution to reach 77 Kelvin. And most of the liquefaction cycles, nitrogen is used as a pre-coolant in order to reduce the temperature from room temperature to 77 Kelvin. The steel industry is a very important consumer of these gases. And you can find lot of liquid oxygen plants on the campus where the steel industry is housed. So, in steel industry, oxygen is used in the production of steel. Basic oxygen furnace uses oxygen instead of air. So, you will find a lot of places liquid oxygen becomes a very important requirement for the steel industry. Nitrogen and argon are primarily used to provide an inert atmosphere in chemical, metallurgical and building industries. So, these gases being inert gases, they are stored in the form of liquid nitrogen or liquid argon instead of storing in the forms of very highly compressed cylinders. It creates problem as far as safety considerations are taken in. The next biggest application is superconductivity. Superconductivity has got various uses in NMR, MRI, magnetically levitated trains, transformers and generators. This is a very important aspect of cryogenics. In fact, superconductivity came into existence because of cryogenics and it has got important usage in various aspects, important being the NMR or the nuclear magnetic resonance and MRI which is a magnetic resonance imaging which you find in hospitals. So, one of the major important usages of superconducting magnet is a NMR which is a nuclear magnetic resonance. It is used by the various pharmaceutical industry to study the molecular structure. If I want to devise a new drug against any particular disease, I have to do NMR in order to understand the molecular structure in three dimensions. What I do for that is an NMR and NMR has superconducting magnets here. What you can see here is a superconducting magnet and in the superconducting magnet, what I have got is a small sample of a chemical of which I want to study certain properties. In order that this magnet becomes superconducting, this magnet could be kept dipped in liquid helium and one can have liquid nitrogen outside. So, if you have seen any NMR facility, you can always see that NMR facility will continuously require liquid nitrogen or liquid helium in order to keep this superconducting magnets in a superconducting state all the time because slowly the liquid helium level will start going down and slowly liquid helium state also will start going down and therefore, we need cryogens to be supplied all the time. The magnetic field which is generated by these is around 10 to 25 tesla. Higher the magnetic field, better is the structure that is visible to us and therefore, the need of superconducting magnet in this case. Similar to that, what you have got is MRI which is a magnetic resonance imaging and this is again used for body scanning. As you can see a picture over here, this is a magnet and then we have got different coils which take a signal of this person sitting over here. MRI is meant for basically body scan while NMR is meant for chemicals. In order that these magnets are kept in superconducting state all the time, they are dipped in liquid helium here and then you can find different shields outside. Sometime this liquid helium will be surrounded by liquid nitrogen or we can use a cryocooler which can produce shields of 40 to 50 Kelvin or 20 Kelvin outside of this liquid helium so that the boil off is minimum in this case. This is a very, very important application of cryocoolers in MRI field. In fact, MRI field has really initiated the research better and better efficient cryocoolers and functioning and also minimum vibrations in these cases and this is the way MRI will be done. The superconducting magnets for both NMR and MRI machines are cooled with liquid helium and nowadays with cryocoolers also. Next application is magnetically levitated trains which run on the principle of magnetic levitation. The train gets levitated from the guideway by using electromagnetic forces between superconducting magnets in the vehicle and coils on the ground. This is the very important applications of superconducting magnet which uses cryogenics to go into superconducting region. This particular thing results in no contact motion and therefore no friction. So, imagine a train running with a speed of 600 kilometer per hour having no contacts with the rails and therefore no friction, therefore no wear and tear, therefore no servicing requirements. It is a great application of cryogenics. Similar to this, the next applications are superconducting transformers, motors and generators. Wherever there are windings involved, wherever there are I square R losses are there. If we could put those winding in liquid nitrogen or liquid helium, the I square R losses are going to be absolute minimum or zero. There are different ways in which this superconducting wires could be achieved. Superconductivity of these wires could be achieved by various cryogenic arrangements, cryogenic systems that we have to study. However, because of superconducting transformers, generators and motors, cryogenics is reaching to a commercial state now. And lastly, I would say the recent experiments which most of you have seen at CERN and now the biggest project on earth is ETER are the important applications of cryogenics in high energy physics. CERN is an European organization for nuclear research which was founded in 1954. It consists of a 27 kilometer accelerator ring with four detectors. Possibly most of you have heard recently the results what you got at CERN. It houses superconducting magnet ring. All the magnet system which is there in this 27 kilometer accelerator, it has got superconducting magnets and all these magnets are kept at 1.9 Kelvin using liquid helium. So, you can imagine an immensely application of cryogenics, the biggest application of cryogenics at CERN. In fact, lot of research in cryogenics originated from CERN because of this big applications. A liquid nitrogen layer of 77 Kelvin is used as shielding for liquid helium. It is an experiment, most of you know it is an experiment seeking answers to Big Bang theory and collision of atomic particles. Basically, it studies the origin of universe in this way. The next big application after CERN has been ETER international thermonuclear experimental reactor. This is an engineering project for nuclear fusion reactor. This is a very important project which is I think the biggest project right now on the earth. The superconducting magnets are maintained at low temperature by gaseous helium. These experiments are carried out to enable mankind to generate energy for future. So, ETER experiments, if you go on NET, you can get lot of information on CERN and ETER experiments and these experiments we seek that this will possibly solve our problems for energy in future. So, I have given you various applications of cryogenics and just in summary, I would like to give space application, application of cryogenics in medicine, application of cryogenics in mechanical engineering, high energy physics, then gas industry and superconductivity. This is in short all the applications of cryogenics in various field which are very important. In addition to that, what we have is a cryo biology, in biotechnology, in cryophysics and thing like that, where they got fantastic applications of cryogenics in this field also. I will stop here. Thank you very much and in the next lectures, we will cover different aspect of cryogenics engineering. Thank you.


Okay, we can't talk about IOLs without going back to Mr. Ridley, the original maker of the IOL. This is one of his surgical videos from 1951. I have to show you this. That's a graphe knife.  That's a graphe knife. Now he replaced some, some four-row silk sutures in there.  You just tear it out, as some of you guys do in surgery. Now you'll see he's just squeezing out the nucleus and of course we didn't realize about endothelial cells there. That's about 20,000 endothelial cells. And then you just flush out the cortex and wash it out. And then this is the, this is the Ridley lands being plighted. This is done with loops. No microscope. And no gloves. Yeah, yeah. So 1951. All right, very good. So I just need to show you that before we go back to our talk. So bear with what's been done to this point. So we want to go ahead and just, just go over IOLs from alpha to omega from start to finish. And of course we have to go back to Copenhagen and see that this is the canals and this is the famous street where all the shops and restaurants that are full of tourists.  And this is just showing you the, the old parliament building from behind. And of course you've got all your classic spires. Now there's kind of like dragging gargoyles climbing up here and snakes going up the tops. I'm not sure what the point of snakes and gargoyles were, but obviously very important when they were carving these out. And there's another close-up. There's the gargoyle and eating the snake that's going up the top of the tower. Well, if you're going to start talking about IOLs, you have to start talking about Mr. Ridley. And this is St. Thomas's Hospital in London. And this is right across the street from part of it. So of course Crandall and I were there. This was at least 10 years ago when we went to there because you can see I still have brown hair. Crandall's hair hasn't changed any so, but that's all natural. He just says good genes. So we decided that we wanted to find the famous plaque for Ridley and St. Thomas's. So we went to St. Thomas's and we said, where is the Ridley plaque? And, you know, of course the response of the people at the desk was, who? What's Jeff talking about? You know, so we finally found it. And this was in some bottom hallway tucked in the back of the hospital. We found it and we took a picture now. So here this says this was the first intraocular lens that planted by Mr. Harold Ridley. Since that time, Mr. Ridley became a Sir Harold Ridley. So he was actually knighted by Queen Elizabeth. And then they've actually moved this plaque up and they've had a little bit of a kind of a little shrine there to honor him. But when we first went, we had to really go down a back hallway to find this. So this honors Mr. Ridley. Here's Mr. Ridley and some of his fishing lures. And he lived to be into his mid 90s. Unfortunately at the end, he was quite deaf. And so if you had to try to have a conversation with him, he just couldn't couldn't hear anything, which was too bad. And when they honored him at the ASCRS meeting, sadly, he kind of got his notes mixed up and fumbled around. And so it was, you know, just thought a happy time, but he couldn't hear anything. But in any event, the bottom line is people honored Mr. Ridley. And that was the important thing at the ASCRS. So this was Ridley's original lens. And what was interesting is that Ridley was a surgeon in the United Kingdom during World War Two. And he started off doing tropical medicine, which is interesting. So he was in Southeast Asia. And then at the beginning of World War Two, and then he was called back to England. By then he'd become, you know, just an ophthalmologist. And he was treating Royal Air Force fighter pilots during the Blitz when the Nazis were bombing London. And what was interesting is as these planes were being attacked and hit by machine guns, the cockpits were shattering and bits of the cockpit were going into their eye. Fertuitously, the cockpit was made up of plexiglass, which is PMMA, Paulingotha methacrylate. And Ridley noted that this material was very inert in the eye. It did not cause any inflammation. And so as he started thinking about ways to treat cataract patients, you know, legend has it that he did a cataract surgery and a student in the OR said, well, what do you put in to replace the cataract?  And I'm not sure if that's true or not. He sadly didn't live long enough for me to ask him. But in any event, during the cataract surgery that was done in the 40s and 1950s, we would remove the cloudy cataract and give people a fake expectacles. I don't know if you guys still see people in clinic with a fake expectacles. They're pretty amazing. They're like a plus 20 coke bottom, basically really thick in the middle and thin in the periphery. And although people could conceivably see 2020 with these, they had just terrible quality of vision. They would have it would be magnified 25 percent. They'd have this rim in the periphery where it would just go around the edge of the lens and you just couldn't see. So they had what's called the jack-in-the-box phenomenon where you could be driving your car and there'd be a car next to you and you wouldn't see them. And then suddenly they pop up out of nowhere. So very, very difficult. So Ridley started thinking about it and saying, you know what? Why don't we come up with a lens implant that goes back inside the eye to replace the cataractless lens that we removed? Now, during this time, a lot of people were doing intracaps where you would remove the entire lens, its caps or bag and its contents. So there's no place to put an eye on. Well, but Ridley was playing around with crude extra caps, as you saw in that video. And so his thought was, you know, we're going to put this implant where God intended it in the posterior chamber. And so he invented this round disc. This is what it looks like. This is an EM of an old Ridley lens. It's this round disc with a little flange around it. The idea is you should put it back inside the lens capsular bag. This was an eye that had a Ridley lens in it for greater than 30 years. And you can see fortuitously it ended up inside the capsular bag. The bag kind of scored around it. Well, as you can see from the video, there were really crude capsule atomies. And so the idea of putting this in the bag was, you know, not a real good idea. I mean, it was a good idea, but it didn't happen much of the time. And so these implants ended up in the sulcus. They ended up dislocating. They ended up with pupil area block. And so lots and lots and lots of problems with this implant. But the idea was set. So that was the idea. And here's the edge of it, too. And so you could see a little bit of rough edge there. They were kind of hand polishing these. Now, interestingly, the company that made this was Rainer, which is still in England and still making implants all these years later. So, you know, 65 years later, Rainer is still making these original implants. So just to give you a little bit of a history of what Ridley went through. So Ridley did these secretly. I mean, the hierarchy in the hospital was very suspicious of, you know, change. Not a, you know, 1950s, not a time of really radical change going on anywhere. And so as a result, Ridley did these in secret and had to really be careful about people knowing about this. And so slowly, but surely, he started presenting this in England and in Europe in this new idea, this intraocular lens. So he came to the United States and he did a presentation at the American Academy of Ophthalmology and Otolaryngology. Following which, the president of the Academy stood up and said, if anyone in America puts one of these dangerous devices inside a patient's eye, I will personally testify for the lawyer that's suing them. This is the chairman of the American Academy of Ophthalmology annual meeting. So this was 53, maybe 54. So needless to say, organized ophthalmology was not in favor of implants or not in favor of fake emulsification. I find it really ironic that this year is the 50th anniversary of Charles Kellman inventing the fecal machine. And the Academy is going to do a big gala. This followed their meeting in New Orleans celebrating that. Again, after the Academy said that fecal was, you know, the, you know, made by the devil and was just these cowboys and buccaneers and sharks using an extra cap is just as good a surgery. So we find it really ironic that the Academy is actually honoring Kellman for his invention. Now, ASCRS, because our meeting is first, it's in May, we're actually doing the true 50-year anniversary because the ASCRS was actually a rebel organization founded to oppose the Academy's opposition to intracular lenses and fecal. So, you know, at that time it was called the American Intracular Implant Society. It was a real rebel organization, so just to give you some background. All right. So bottom line was Ridley came up with this idea and said, you know, I think this is a great idea. Americans were banned from doing anything. So all IOL research that took place for the next 15 years took place in Europe. Now, because most doctors were not doing extra caps as Ridley did, they were doing intracaps. So what you would do is you would put in some alpha chymotrypsin, you would dissolve the zonules, you'd pop the whole lens out, bag and all, nice clean surgery, put in lots of stitches and give them any fake-head glasses. So that did not leave you a lens capsule to support an IOL. So doctors said, well, why don't we put an IOL in the anterior chamber? So here you see kind of a schematic of one of the crude anterior chamber IOLs. Now they hit on a good material. PMMA is very inert, still material that we use today. And so one of Mr. Ridley's students, Peter Choice, decided, OK, why don't we develop some anterior chamber IOLs? And so Choice went through nine different iterations of his IOL. So this was the, you know, this was the Mach 1, the first one that he did.  It sounds pretty cool. Like, you know, the Razors, the Mach 8, you know, Schaver from Gillette. So this was the Mach 1 and he went through nine different iterations. And now this was the one that took hold. This was the Mach 8, Roman numeral 8. So this was the Choice lens. And you can see it's a one-piece PMMA. It's got these foot plates on it. And if this lens were well-finished and well-sized and placed under the eye properly, it did OK. And so this lens was the lens that most people started using when they were starting to use IOLs. This was the later version. This was the Mach 9. This one didn't take off quite so well. Now some of the problems that these lenses could cause is that they're in the anterior chamber. They're scraping on the iris. They're, you know, going into the anterior chamber angle. If you look right here, there's a little bit of blood here. In fact, when the U.S. tried to jump on the bandwagon and copy these, several U.S. companies popped up and said, hmm, this is maybe a good idea. Why don't we start making these? They started making choice rip-offs. And the problem with the choice rip-offs is they weren't well-made. And that caused the beginning of what you guys now know as the UG syndrome, uveitis glaucoma hyphaema for anterior chamber inflammation. You can see another problem with these lenses. They came in two sizes, kind of like cutting knots, you know, too long and too short. And so if they were too long, or if you were putting them in and pinch the iris, you would get this oval cat's eye pupil. And of course, you'd get the chronic uveitis, chronic glaucoma, and the UG syndrome. And so here you see, this is an eye, this is an eye that's been cut in half. Here's the anterior chamber angle there. You can see that it's actually tucked. The root of that iris behind where that foot plate was that actually caught it and tucked it, gave it cat's eye pupil. What do we have? Ah, Eileen, we do have a senior. What's going on here in the angle? There's a lot of pigment there. Yeah, so pigment dispersion, pigmentary glaucoma. So you're right into a lot of problem with these, these anterior chamber lenses. This is the edge of a copy choice lens that was made in the U.S. Look at that. I mean, just for fun when I was a fellow, I wish I still had that picture. We took a Coke while it broke it and then did an EM of the edge of the Coke bottle and it looked smoother than that. So you can imagine what that's gonna do, scraping the iris or scraping any part of the anterior chamber of the eye. So these lenses had to be properly sized, properly finished. And so choice, I made the mistake. I was a young Dave Apple fellow presenting our work on these choice lenses and of course, choice was on the panel as I'm presenting this and he was very upset, very huffy. These are not my lenses. These are unlicensed copies. So we had to say at that point, choice copy or choice-like lenses after that because his lenses did not do this. All right, so because these one-piece lenses were hard to fit and couldn't go well in the anterior chamber, companies started to say, well, why don't we make three-piece lenses? And as the technology improved, the optic was still made out of PMMA. It still wasn't foldable, but they were able to fashion haptics out of proline, polypropylene. Okay, so those of you who are outdoorsmen, polypropylene is Gore-Tex basically. And so they took a very low-water content Gore-Tex and they made these polypropylene haptics. And so these were the beginning of what are called the closed-loop IOLs, closed-loop anterior chamber lenses. And this is the Azar 9 lens Z lens. This was an interesting lens because at one time, this was the most popular lens in the United States. Very easy to put in.  These looked really good for about 18 months. So all these papers started coming out, saying, oh, these are great. Well, the problem is is after a while, these lenses were not so good and caused some problems that we'll talk about. So immediately people jumped on the bandwagon. So this was, and you named it after yourself. So if you were a surgeon, you would design one of these, the company would take it and you'd name it. So this was the Leiske lens, Larry Leiske named it after himself. And this one instead of the loops being a little bit rounded, they were more rectangular. And then they would even make them out of one piece PMMA. If you look at these carefully, look at these that were removed, look at all that pigment and stuff on the edge of the haptics that are there.  And then you see these around. These were called the stable flex lenses. Now, unfortunately, these were used length by a couple of busy surgeons here in Salt Lake. And so Alan Crandall and Randy Olson took out more of these than they want to talk about. And these were a real bugger to take out. These would fibrose into the angle and these were just held to remove. So bottom line is what happened to these? What did all these closed lube IOLs cause? Well, first of all, if you take a closed lube IOL and you squeeze it, that optic will either bound forward or bound backward as what's called vaulting. And so every time a patient rubs the eye, which patients never do, right?  These haptics would bounce off the endothelium. And so one of the side effects of these closed lube anti-chamber lenses is you got significant corneal edema. These closed lube would dig into the iris. And as a result, you'd get breakdown of the blood, aqueous barrier, you'd get chronic ugg syndrome. So they'd get corneal edema, they'd get chronic ugg syndrome. These were very, very difficult to do. And this is a cornea from one of them. And so one of my first projects when I was a Dave Apple fellow is we gathered about 18 of these Azar 911Z lenses that cause corneal edema. And so I had 18 corneas sitting in jars on my desk at which time an ocular surgeon here who set up the first cataract institute in Utah, the so-called Eye Institute, was sending limos around to pick up patients from their house to drive them for surgery and giving them flowers afterward. And was lecturing all over Utah that this lens was fantastic and he was advertising in the papers that he's the only one to use this and that there's no complications. And as he's doing this, I have 18 of these in a jar on my desk saying, no, no, there are complications. And so we did our best through Dave Apple's lab to get the word out that maybe this isn't the best lens to use. Here's a close-up of one of these open loop, I mean closed loop enter chamber lenses. This is an autopsy, I just had the cornea removed. Here's the iris, here's the edge of the eye well. Look at the open loop, look at it going into the angle now. Where does that go? It's buried in a tunnel. So you get this tunnel of iris growing over it in the angle. Here's what it looks like pathologically. Here's the root of the iris, iris stroma and loop digging in. So you can imagine what this would do. It would cause chronic glaucoma, oxyndrome, corneal edema. Here's another one with one of these stable flex lenses. These were really difficult because you could get all four of those little loops to have an individual tunnel over them. And so when you remove these, these were tough.  If you pulled directly toward the center of the pupil, you'd get an aerodialysis and a massive hyphema. So you had to really cut these on the edge and then back them out of the tunnel. It's very, very difficult to do. Now this is an interesting lens. A guy named Dubroff in Washington, D.C. said, well, these closed loops are causing problems. Why don't we make them open looped? And so this, you see it's got a propeller. It's got three loops on it. These broad, C-shaped haptics. The problem with this is these broad, C-shaped haptics would go into the angle and would close it off.  You'd get a severe glaucoma. And these were not very well finished. So you'd get a chronic plug syndrome from these. Unfortunately, there was an old stubborn surgeon in town here who bought a whole consignment of them and insisted on putting them in up until 1987, when I came back here as I'm attending. And he did intracaps in 87 when everybody's doing extracaps and put in these anterior chamber Dubroff lenses. And so he's since passed away, but Alan Kendall said deftly that he was the leading cause of preventable blindness in Utah. And so I had the uncomfortable position of actually testifying against him as his privileges were being pulled, so. But doctors are stubborn. Sometimes we stick with what we believe, whether it's correct or not. Does that sound familiar with an election? Post-truth era, sorry about that. Okay, so what are the most common side effects of these lenses? Corneal edema. If you look right here, you can see significant corneal edema. All right, so what are we looking at right here, Chris? Some corneal edema. What do we call that? It's a bolus carotopathy. Bolus carotopathy, exactly. So you see that big boli there, separating the corneal epithelium from underlying bone layers. Bolus carotopathy, very commonly seen. Why would I be showing this? Let's see a second here. Ashley, why would I be showing this? What is this? This is retinase. What part of the retinase are we in? See, so it's also, it's not in the macula. It's in the macula. What are we seeing right here? That's actually exudate, sitting in the outer plexiform layer in the macula, which is called Henle's layer. So this is cystoid macular edema. So that's another side effect of chronic breakdown of the blood aqueous barrier, cystoid macular edema. So in two weeks, you will know these layers cold. Lots of layers in the retinase in two weeks, you have that to look forward to. So these chronic inflammation could cause corneal edema, could cause glaucoma, could cause, ux, not drugs in German, could cause cystoid macular edema. See, I mean. All right, so finally, Charlie Kellman, the guy who invented the fake emulsification, said, all right, these lenses are causing problems because they're closed loop. Why don't we make an open loop into your chamber IOL? And so his first iteration, we used to call this the pregnant seven. So if you look at it, there's a seven and it's pregnant. The pregnant seven. And so he had this, it was shaped like a seven and it was three piece, three point fixation. And Charlie's argument was, if you were in a bar and had an unstable, unlevel floor, a three-legged stool was more stable than a four-legged stool. Four-legged stool would wobble, three-legged stool would be stable. So that was his argument behind this. The problem is that if you put this in, it was very stiff. And so you would get, overling of the pupil, you'd get a lot of problems with these. And so he tried to make the haptics thinner, which was good, but still that three-piece design just didn't work. So Kelvin being a smart man within about a week decided, okay, maybe I was wrong with the three-piece. And so he, or with the three-point fixation. So he immediately jumped in and said, okay, four-point fixation is better. So the nice thing is, is you never have to say, gee, I was wrong. You just have to say, here's the latest, most improved version of Tide. It gets your clothes even wider. It's not that the old Tide was worse. It's that this is even new and improved. So the new and improved Kelvin lens, called the Multiflags, now had four-point fixation in the interior chamber. And it's open looped. And the nice thing about that is if you compress those haptics, they take the compression and the optic doesn't vault. So we did a bunch of studies in the lab, squeeze them and these would not vault. And so as a result, you get much less corneal edema, much less Ux syndrome with these. And is this a familiar? Yeah, this is a lens we use right now, 30 years later. And so Kelvin hit on a nice idea. The other nice things about these is these were relatively flat rather than round. So they wouldn't dig into the angle they'd slide over them. And so if we have to put in an anterior chamber IOL to this day, this is the one we use, the Kelvin Multiflags. All right, so here's the old Apple Corp. Sitting in the corner of the cafeteria. Dave Apple couldn't do this in the lab. So he had to go to the cafeteria to get coffee and we lay out all of our stuff here. And he would dictate and we would put these pictures together beautifully, fellows and students. And we now notice we held that up right there because we were on the cover there. So we held that up for the picture. The original Ocular IOL and Ocular Surgery News. You'll recognize that it's still the Ocular Surgery News. It still comes out, you know, twice a month. So there's the original Apple Corp. All right, so we had t-shirts made too. We took the Apple Apple and took a bite out of it and said Apple Corp. So at the time that people were doing these anterior chamber IOL modifications, people said, well, why don't we just clip an IOL to the iris? And that's a good idea, right? You clip it to the iris, it's gonna be away from the corny. It's not gonna cause any problems. So this is called the B-course lens. B-course was an ophthalmologist in the Netherlands and so this is the B-course lens, this is the for loop. And the idea, let me see if I've got one in cross-section. But the idea is two of those loops go in front of the iris, two go behind it. You literally clip it to the iris. And so that was the B-course lens. And then another doctor named Jan Worst, who was in Belgium, came up with this and a nice thing, the funny thing we had a good time with this one, this was the Worst lens. And so we agreed fully in the lab that this was the Worst lens. And so the idea is is that you would put this little peg on here and it would help clip it to the iris with the loops. And then it even had these suture holes so you could suture it onto the superior part of the iris. And so the problem is when you put these for loop IOLs and what happens when the retina guys won't examine the peripheral retina, you dilate them lively and the IOL would fall into the anterior chamber, fall into the vitreous. So these Worst lenses, you put a suture in them, they would hold them in place when you dilated the pupil. But the problem is is all this hardware rubbing against the iris, you can imagine what that's gonna do. These caused lots and lots of ugg syndromes. The other problem is these haptics that were made out of proline degraded. So this was the mud flap degradation that you could see in the proline when proline touches uveal tissue. Now, how is this applicable now? If you take a proline suture and you suture an IOL to the iris or to the silvery sulcus, a 10-0 proline will degrade just like this. And eventually that suture will break and that will dislocate. So you don't wanna use 10-0 proline when you suture an IOL. You wanna use something bigger and stronger, at least 9-0 proline is not Gore-Tex sutures. And so this degradation happened to proline haptics. It also happens to proline sutures. So it's a surface degradation. So because of that, a company said, hey, why don't we make these out of titanium? Great idea, right? Titanium, does it degrade? It's good stuff. Well, first of all, titanium is really heavy. So these IOLs will like sink down. Also, if you're gonna put them in any kind of a magnetic field, that may be an issue. So titanium lasted for about three days. So that lasted about as long as the pregnant seven. So not a very long. But again, I'm showing you this to say, look, people thought of all kinds of stuff. Very many people had ophthalmology. All right, so here's one of the worst lenses. It was held on here by a suture, which is since broken. That little tab that was attaching it to the iris caused a tremendous amount of iris atrophy there. You can see corneal edema here. And look how irregular that pupil subussed the worst lens. Now, what happens to these lenses that were attached to the iris? This is the haptic of one of these iris-fixated lenses. It's literally fixated to the iris. I mean, there's iris attached to that. When you take this out, you couldn't remove it without removing part of the iris. So these were very, very difficult to take out when you were taking them out. So this was the one, the four-loop lens. The idea is you would put it into the ciliary sulcus. And then as people started going to extra caps, they even started trying to put it in the bag. Now, this was fun. Copeland, a company came up with IOLs that are shaped like a propeller. Two props would go forward, two would go backward. You'd fix it to the iris. These are little Copeland elves at Christmas time, wishing you happy holidays, making a little IOL. So this was an ad from the journal that was there. These were pretty cool, because it gave you a square pupil. So here's the tabs in front of the iris. There's the tabs behind there. She'd get a square pupil from these. Imagine the retina guys. They must have loved these, because it was really difficult to see the peripheral retina. There are the pigment granules on the surface there. And you can't even see through this. This is because of the corneal edema that this caused. My favorite is like this one, proven, safe and effective. Discontinued. So I love that ad, you know? It's like proven, safe and effective. But we discontinued it anyway. You end up with safe and effective. So over time, as surgical techniques evolved, people went from doing intracaps to doing extra caps and then eventually fake go. And so because of that, as the capsular bag became available again in the early 80s, then people started saying, wait a minute, why don't we put an IOL inside the capsular bag, which is where it belongs, right? In the posterior chamber and the capsular bag away from the anterior chamber. And so Steve Shearing, which is interesting, invented this posterior chamber lens now. Again, I've been doing IOL research forever. This is all he ever did. I mean, he's a private guy in Las Vegas and he invented the lens, which is fantastic. But he never did anything after that. So this is the Shearing lens. And you'll see it looks like an umbrella. It's that little J-shaped lens right there. It looks like a little umbrella stand. So the problem with that is, as you can see that J was straight out and it tended to ovalize the capsule. So this is when people saw this and immediately jumped on it. IOL evolution was taking place at this point by the day. And so a guy named Simco in Oklahoma City said, well, if those J-loops aren't very good, why don't we make C-loops? You know, make it fit better in the bag. And so he made these broad C-loops. So the idea is you put that in the capsular bag, these are all fixation holes. Why so many fixation holes? Well, remember, we didn't have fiscal aesthetics then. There was no heel on yet. It was just coming on board. And so people had to try to squeeze these in just under air or under BSS. And so he had these various little holes to try to put them in. And then Bob Sinski came up with his variation of this, which was the modified J. And so you can see his modified little bit instead of coming off in the middle, it came off to the side and he put this to the look. And now in IOL, one of the first companies to make these, of course they put their name on here and the power. So you would never have any question. That was the IOL power. The problem is, is these would act as a little nitrous. So you'd get little inflammatory cells around these and so that you don't want raised letters on an IOL optic. But this is the lens I trained on. This was the ultimate lens. There would never be a lens better than this. I caution you guys as you're going through residency, you're gonna go through very good and say, wow, we have the most up-to-date surgery that's ever been invented in all of mankind's history. It'll never get better than this.  Geez, that was so crude. So just wait, 10 years from now you'll be laughing on what you're running now. But this was the ultimate. You did an extra cap. You put this implant in, you tie off the eight stitches 12 weeks later, patients would come back and you'd give them their glasses. No CME, no UGG syndrome, oh my God, this was the ultimate surgery. It would never get better than this. So this was the Sinsky lens. Well, initially people argued about where you should put that lens. And there was a group at Johns Hopkins at Wilmer because they were Wilmer, they were obviously correct, that said you should put it in the sulkas. Because people can't get it in the bag, they're just not good enough yet. So just put it in the sulkas and you won't have any tilting in their regularities. So again, Dick Green and Dave Apple went the rounds for a couple of years saying we said put it in the bag and they said no, put it in the sulkas. Well, okay, I'll let history judge. Where do we put the implants in the bag? So the Apple Core was correct on this one. So what's the problem if you put an IOL in the sulkas? What's going on here?  What's going on here? It's like iris atrophy. And look at the pattern of the iris atrophy. How come it's shaped like that? Because of where the haptics are. Exactly, so if you put haptics in an optic in the sulkas, they can scrape on that posterior iris, you can get atrophy there where the haptic optic junction is, you can get atrophy where the haptics are. So the idea is don't put it in the sulkas, put it in the bag. And so this is an eye, here's the iris, here's the angle back here. So look, big, peripheral anterior synecine. Here's that Iowa loop all the way back, almost at the major Iowa circle. So you put a loop like that, a big Iowa loop like that in the sulkas, it can erode all the way in there. So the idea is you want to put it in the bag. And this was an old Sinsky lens. This had been in the eye for about 20 years. And look how beautiful that looks. I mean, it's completely in the capsular bag, there's no transillumination, there's no iris scraping. So we really want to put Iowels in the capsular bag. And there's a nice path picture, here's the root of the iris, here's the ciliary body, look at that loop in the bag, look how beautiful that looks. So that's what we put in right now. All right, so as companies got better at making Iowels, they started making now one piece instead of three piece poster chamber lenses. This is PMMA, and they came up with a technology called lathe cutting. And so you could actually do a micro lathe that would cut this out like a cookie cutter. You'd cut out this one piece lens and look at the finish on there. I mean, it's just beautiful, they would tumble polish them.  And it would micro polish these beautiful, I don't know if you guys as kids had rock polishers, and you put a rock in there and you tumble them for like two weeks, and then it would make them really smooth. It's the same idea with Iowels. And so this is a one piece modified C. lube, PMMA poster chamber Iowel. Look at how beautiful that looks. So the late 40s and 50s women really started doing these and then he spoke here, and so no one was doing any sort of cataract surgery at that point or at least they did in Iowels. So then at what point does the US start doing things again? In the 1970s, Americans snuck over to Europe and smuggled these illegally in their bags, and then came back and tried to put them in. And then- They just were doing only AC, only cataract chamber. Anterior or iris fixated, that's what they were at that time. Yeah, yeah. So again, I gotta tell you the story. Some of you guys who were in path readouts heard the story, but I have to repeat it for everybody here. When Iowels first started being widespread, and this was in the very, very early 80s, people started putting these in, I was a climber, put these in and put a minimal Ralph Nader, and his Nader's Raiders got with of this, that surgeons were putting these dangerous devices illegally in people's eyes and they were gonna shut it down. So they got a hold of a congressman that were very receptive to them, and so they set up a big congressional hearing to shut down the use of Iowels in the US. Well, at that time, fortuitously, Dick Kratz, who was a surgeon in Southern California, his one of his patients was an actor named Robert Young. And so you gotta realize, this is pre-cable, pre-internet, there were three networks, and so on, you know, whatever, Thursday nights, you know, two thirds of Americans sat in front of their TVs and watched the same shows, and so the number one show in America was called Marcus Weld, MD, starring Robert Young. And he was America's doctor. He was the most trusted man in America, more trusted than Walter Cronkite, and he was a character in a TV show. He would see two patients a day, he was a private practitioner, he would visit them in the hospital, he'd go to their houses and bring them medicine, he was America's doctor, well, he had cataracts, Dick Kratz put an IOL in his eye. And so when it came time, they did all this testimony against Iowels, and then Dick Kratz testified, and then they brought Robert Young out, and he testified that this device saved his career and his sight. And so afterward, he walks into the hallway and there's a million cameras and lights and flashes, and so the press is always, you know, Dr. Weld, these are the greatest thing, and so Congress couldn't shut it down, which is really fortuitous. And so because of that, they set up a quote IOL study, and that went on for years, the FDA sponsored it, and so even when I was a resident, you had to sign up to be an investigator for every company to put in an IOL. So at that time, there were like 20 of them, so it would be like the first day of your internship, you would have to fill out 20 investigator forms to be an investigator, and you have to report your results for these, and so they did this, and it did show that Iowels were safe, and so the rest is history, but it's fortuitous that Dick Kratz was operating on America's doctor who testified, or else they would have shut these down. All right, so we can't talk about Iowels without talking about cataract surgery technique evolution because you can't understand that, so this is how cataract surgery was done in the olden days when Crandall was a resident, so this is an intracap. So you would make an 11 millimeter opening, you put some stay sutures in there because you didn't want to let the eye get any explosive, you lift up the cornea, and then you'd put in alpha chymotrypsin, dissolve the zonions, and you'd take a cryoprobe, just like retina cryoprobe, and you'd stick it to the anterior lens capsule, it would freeze and hold it, then you'd go through it, and pop the whole thing out, and then you would have just nothing posteriorly, and then you'd put in your anterior chamber, your eye was fixated, Iowel, and then you'd close all those sutures.  It was kind of cool because you could vary your aspiration rate from zero to 500 millimeters of mercury, depending on how hard you pulled back on the syringe, so you really did have good control of doing that, so you would suck out the cortex manually, and then you could put an IOL in the posterior chamber. Look at these pretty wounds we made. You made this nice 11-millimeter wound, and then when you were done, you put in about eight interrupted stitches, and you would cut them periodically to fit your stigmatism. Well, of course, finally, Kelman invented the FACO 50 years ago in this year. Interesting story because Kelman was at the dentist, and the hygienist was treating his plaque with his gums with an ultrasound. And so he says, well, wait a minute, if ultrasound can, in a removed plaque, can't we use ultrasound to grind up a cataract? And so that was his idea, and his first ultrasound machine was like, as big as this whole platform, and this high, and of course took him three hours to take out the IOL, but that was the cataract, but that was the impotence, and from that, we have the FACO mostification we have today. Along with the evolution of the equipment, the wounds evolved too. And so as we were able to make smaller and smaller incisions, we were able to make better incisions. So this was the standard three-plane incision we made. If you'd start about a millimeter and a half back from Lula, and we should go down halfway, then you dissect out, and you enter the corner, and that was your standard three-plane incision. As foldable IOLs were invented, then we're able to make our clip-coating incisions like we do today. So that's our clip-coating incision. So it didn't make any sense if you're doing this wonderful FACO through a three-millimeter incision, then you have to open your incision to six millimeters to put in an IOL. So because of that, companies started working on foldable IOLs. And the first foldable IOL was the plate-type silicone, Tom Masako invented it in Southern California, so they called it the Masako Taco. And you can see you put it in an injector and roll up like a soft-shell taco, and you just put it in the eye. You could put this through a three-and-a-half-millimeter incision, you'd have to expand the incision. So interesting idea, so silicone was the first available material that they could make an IOL out of. And here is a plate-silicone lens, and whoever was in the lab with us last week, we had one of these. They still put in ones in a while, and it was a plate-silicone lens that had these large holes in it, and you were just injected right in the bag. Well, immediately, companies jumped on that and said, hey, why don't we make these three-piece? So they would put proline haptics on this, make them three-piece, you could either put them in with a force-up or an injector. Initially, the injectors weren't good enough to put in three-piece lens, yet put them in with a force-up. But silicone still, low refractive index, not as bio-compatible as some of the other materials. So not the ideal material for foldable IOL. And so people started looking at other materials that they could use. And I'm not gonna talk a bunch about star, but one of the other materials they looked at is a hydrophilic acrylic, a water-loving acrylic, or so-called hydrogel. This was one of the original ones that was made in the US. They would graph the haptics on it. This was the hydrophilicone lens. And these look great, again, for about 18 months. The problem is, is that these early hydrophilics would calcify. And so in the US, the two most popular brands, both would calcify after a couple of years. And so you can imagine that killed both companies. So these died in the US. In England, Rainer kept working on these, and there are companies in Europe now that make very good hydrophilic acrylics, and they're used a lot in Europe, not so much in the US. Well, finally, we came to the present, at least gold standard, the hydrophobic acrylic. And so Alcon was the first one to make the AgriSoft, and the idea is that it's a very high refractive index, and so you can make it thinner. It has relatively good biocompatibility. It's got relatively low capsulotomy rates, and so this is the material that we do now. And initially it was a three-piece, and now it's a one-piece with half-take. And so hydrophobic acrylic is pretty much the material that we use now. And the rest is history.  So this is the Oddfellows Palace. So we had our triple IC dinner there at the Oddfellows Palace. Kind of a cool, 400-year-old palace there in Copenhagen. So I think we say goodbye to Copenhagen now, so next week I'll find some other travel slides with you. So next week, you're back on the hot seat again. I believe it's called Khoma, and then Retina. So look up your schedule. I think that's the next two weeks. So look, you know, read that section in the BCSC, okay? Questions in four minutes? Why is it called the Oddfellows Palace? Ooh, good question. Oddfellows is an organization that's been around for about 400 years, and I'm not sure what the organization stood for, but it's an organization that built this. But very ornate in science. I love these European palaces and very ornate. Oh, so I can tell you the triple IC story. Triple IC is the International Inplant Club. And basically, Mr. Ridley, and by another dozen people, started their own society, their own club in 1967. And so it's written by him that it is a society that is by invitation only. So who special people are invited? So every year, about four or five new people who have done work in Iowa are being invited, and it's just an excuse to get together.  I am. All right, all right, make sure your attention. Thank you. Thanks.


motion under gravity right down is motion under the influence of how much is that gravity m into g that is g, m into g is the force, so if object constant ok direction motion right direction is down which is constant and right to the easy ok this acceleration if observations from this topic under the gravity motion to be constant which is g which is 9.8 meter per second square unless taken otherwise ok. Now this chapter is motion in one dimensional one dimension ok so when the stationary net force is 0 when I release alright so how should I release it or how should I throw it so that it moves in a straight line cross straight line or in an object from here g is g I don't know root to s by g square or t you will get to h by g understood ok what time it takes to be in terms of g and h just write down the equation initial and final equation h if you take it down initial classes ok so use s equal to ut plus half at least this is minus you understood another question


Hey everybody, welcome back to magic orthodoxy.  He's out in Germany.  This is his second deck release Okay, you might remember he did the first black roses playing cards deck and we did a review for that as well This is his second deck release if you want to learn more about him You can go check out his website at blackrosesplayingcards.com this second deck polyantha is very simple and very streamlined It's actually completely devoid of any color. It's entirely black and white deck And as you can see just the tuck case is very minimal Just that black roses symbol all the way around with no other scripting or wording And then the bottom has a little bit about black roses playing cards, but that is it So that is pretty much it for the tuck case. Let's take a look at these cards These cards were printed from a makeplayingcards.com, MPC As you can see from the back design, it is very similar to the tuck case It's just a black roses playing card icon repeated throughout on the back And it goes all the way to the edges. It's a full bleed So I guess it kind of makes it a casino back Kind of a little bit in that there's no poker border. Okay, and so again completely devoid of any color There's no any of reds or blues or yellows or anything like that It's a completely a black and white deck with this deck are going to get two original jokers It's the black roses black roses one going up and one going down So it is a two-way image and you get two of these and they're completely identical The other thing you get in this deck is a little tiny pamphlet It's a little in instructions that tells you how to read the back design. Yes These are reader backs And so this is the magical device that allows a magician or a mind reader or a gambler to be able to Determine the face value of the cards without looking at the face It's pretty cool and it stays completely hidden from your spectators Although once you know the secret you'll be able to see it right away again because it is a black and white deck That means that there are no red pips and indices every single pip every single font in the corner is black And so one card looks just like the next as with the previous black roses deck The thing that sets this deck aside from others is the unique and original playing cards Daniel Schneider has put together these cards have all original faces and court cards These people are all either backers of the original black roses deck or the some of them are celebrities And some of them are just friends of Daniel Schneider's that is my review for the polyethy deck from black roses playing cards We'd like to thank Daniel Schneider for allowing us to have this deck so that we could do the review for you And as always we recommend that you like this video just so other people can find it faster We also recommend that you subscribe to this channel just to stay up to date on the latest in cards and card magic If you want to follow me on social media, you can I'm at facebook.com slash magic orthodoxy twitter.com slash magic orthodoxy And instagram.com slash magic underscore orthodoxy. Thanks. Bye