Carbon Nanotubes Uses and Properties

Carbon Nanotubes Uses and Properties ABSTRACT: For the first time in the human history, we are close to being able to manipulate the basic forms of all the things, living and inanimate, take them apart and put them together in almost anyway the mind can imagine. The sophistication with which scientists are learning to engineer matter at the nanometer scale is giving us unprecedented mastery of a large part of our environment. The world of the future will be defined by how we use this mastery. Nanotechnology is engineering at the molecular (groups of atoms) level. It is the collective term for a range of technologies, techniques and processes that involve the manipulation of matter at the smallest scale(from 1 to 100 nm2). Carbon nanotubes have been under scientific investigation for more than fifteen years because of their unique properties that predestine them for many potential applications. The field of nanotechnology and nanoscience push their investigation forward to produce carbon nanotubes with suitable parameters for future applications. Carbon nanotubes are one of the most commonly mentioned building blocks of nanotechnology. With one hundred times the tensile strength of steel, thermal conductivity better than all but the purest diamond and electrical conductivity similar to copper, but with the ability to carry much higher currents, they seem to be a wonder material. Field effect transistors using carbon nanotubes came into existence, these have a extremely good properties. CARBON NANOTUBES: Evolution of Nano Importance of Nano in present day scenario Moores Law Greatness of Carbon Graphene Carbon nanotube Synthesis of CNT Properties of CNT Purification methods Real time applications GREATNESS OF CARBON: Carbon is the 4th most abundant element in the Universe by mass after( Hydrogen, Helium and Oxygen). Forms more compounds that any other element, with almost 10 million pure organic compounds. Abundance, unique diversity and unusual polymer forming ability at the temperatures makes the element the chemical basis of life. CARBON NANOTUBES: Carbon nanotubes are long, thin cylinders of carbon which were discovered in 1991 by Sumio Iijima. A sheet of graphene rolled in cylindrical structure results in Carbon nanotube of 1 atom thickness and diameter in nano scale. Nanotubes have a very broad range of electronic, thermal, and structural properties that changes due to change in length, diameter and chirality or twist. Types of Carbon Nano Tubes: Single walled: In these single walled nano tubes are narrower than the multi walled nano tubes ,the diameters typically in the range of 1-2nm ,and tend to be curved rather than straight. In these SWNT only single layer of grephene .Catalyst is required for synthesis .Bulk synthesis is difficult as it requires proper control over growth and atmospheric condition .In these SWNT Purity is poor and less accumulation in body .Characterization and evaluation is easy .It can be easily twisted and are more pliable. These tubes are used to make super strong amour bodies .These single walled nano tubes are used as elastic property and used to make bullet proof vests. Multi walled: Multi walled nano tubes consists of multiple layers of graphite rolled in on themselves to for a tube shape .There are two models which can be used to describe the structures of multi walled nano tubes .In these MWNT multiple layer of grephene and can be produced without catalyst Bulk synthesis is easy .Purity is high ,more accumulation in body .It has very complex structure .It can not be easily twisted. Synthesis: Laser ablation: A pulsed or continuous laser is used which will vaporize a graphite target in an oven at 1200c . Oven is filled with helium argon gas .In order to keep the pressure at 500 torr ,Since the optimum background gas as catalyst mixture is the same as in the arc discharge process Laser ablation method is similar to arc discharge method .This method is vey expensive so it is mainly used for SWNT’s laser vapourization results in higher yield of SWNT’s with narrow size distribution than those produced in arc discharge process .Catalyst used for SWNT is NI:Y (4.2:1 At%). Arc Discharge Method: Arc Discharge method has been reported for producing carbon nano tubes .In these method nano tubes are produced through arc vapourization of two carbon rods placed end to end with a distance of 1mm in an environment of inert gases such as helium argon at pressure b/w 50 to 100 amps driven by 20v which will create high temperature discharge b/w two electrodes ,due to this anode wil get evaporated and rod shaped tubes will be deposited on cathode.Bulk production of CNT’s depends on uniformity of plasma arc and temperature of depositon The Main principle is carbon nano fibres are good at absorbing energy so they can absorb the energy coming from the bullet .The inherent property of elasticity makes the bullet to rebound .Its is 100% stronger thean steel.Lighter than aluminium.Conduct electricity as copper .These fibres can be used as space elevators . Purification Of CNT’s: Nanotubes usually contain a large amount of impurities such as metal particles ,amorphous carbon ,and multishell .These are different steps in purification of nano tubes . Air Oxidation: The Carbon nano tubes are having less purity ,the average purity is about 5-10%.So,Purification is needed before attachment of drugs onto CNT’s .Air oxidation is useful in Reducing the amount of amorphous carbon and metal catalyst particles (Ni,Y). Acid Reflexing: Refluxing the sample in strong acid is effective in reducing the amount of metal particles and amorphous carbon ,different acids used were hydrochloric acid (HCL),nitric acid(HNO3)and sulphuric acid (H2so4)bt HCL is identified to e ideal reflexing acid . Surfactant aided sonication, filtration and annealing: After the acid reflexing ,the CNT’s were purer but ,tubes were entagled together ,trapping most of the impurities,such as carbon particles and catalyst particles ,which were difficult to remove with flitration .so,surfactant –aided sonication was carried out .sodium dodecyl benezene sulphonate (SDBS) aided sonication with ethanol or methanol ,as organic solvent were preferred cz it took the longest ime time fr CNTS to settle down ,indicating an even suspension state was achieved .The sample was then filtered with un ultra filtration unit and annealed at 1273k in N2 for 4H .Annealing is effective in optimizing the CNT structures .It was provided the surfactant –aided sonication is effective to untangle CNT’s thus to free the particulate impurities embedded in the entanglement .Nano tube can also be purified by multistep purification method . Real time applications: Carrier for drug delivery: Carbon Horns (CNHs) are the speherical aggregates of CNT’s with irregular Horn like shape .Research studies have proved CNT’s CNH’s as a potential carrier for drug delivery system . Genetic Engineering: In Genetic engineering ,CNT’s and CNH’s are used to manipulate genes and atoms in the development of bio imaging geneomas protemics and tissue engineering .The unwound DNA (single stranded )winds around SWNT by connecting its specific neucletoids and causes change in its electrostatic property .this creates its potential application diagnostics and in therapeutics Nano tubes and nanohorn’s can adehere various antigens on their surface ,hence act as source of antigen in vaccines .Hence by use of nanotubes ,use of dead bacteria as source for antigen which is sometimes dangerous can be avoided . Pseudo spark switches: These are switches which work upon principle of field emission, this emission is achieved by triggering. Generally the triggering methods are Surface discharge triggering Optical triggering Pulsed low-current glow discharge triggering But cnt’s have a good emitting properties when compared from above methods. For field emission cnt’s are used as cold cathode emitters. The field emission characteristics of cnt’s are mostly reported at high vacuum pressures of 10^-6 and 10^-7 torr. Usage of cnt’s for field emission resulted in good properties and working of pseudo spark switches in both high pressure and low pressure vacuum..

Biography of Robert Frost Essay -- American Poets Robert Frost Biograp

â€Å"Rightly or wrongly, Robert Frost has achieved a reputation as a poet of nature†¦Ã¢â‚¬  (Gerber 155). Yes, Frost does use imagery of nature in his poems, but to say he is a â€Å"nature poet† is distorting his poetry by overlooking the poem’s darker complexions (Gerber 155). An aspect of his poems that is frequently overlooked is the main character’s internal conflict. In â€Å"The Road Not Taken† and â€Å"Stopping By Woods On A Snowy Evening† characters are faced with an inner conflict metaphorically described by nature. In these two poems Frost uses nature to hide the reality of how self-conscious the main character actually is. Robert Frost was born in San Francisco, California on March 26, 1874. When his father died in 1885 he moved to Massachusetts with his mom and sister (Sweeny and Lindroth 5). He spent his whole life in the Massachusetts area. â€Å"Frost attended high school in that state, and then Dartmouth College, but remained less than one semester† (Michalowski). At the age of thirty-eight Frost decided to move him and his family to England. While in England his first book, A Boy’s Will, was published in 1913. A few years later he returned to America where his second book, North of Boston, was published (Michalowski). Although he spent three years of his life in England, â€Å"†¦little of his verse reflects any specific English imagery† (Sweeny and Lindroth 11). Massachusetts and other New England areas were the setting for the majority of Frost’s poetry. The nature in the New England area played a big role in his life and influenced his poetry a lot (Sweeny and Lindroth 7). â€Å"Nine generations of New Englanders had produced Robert Frost, and he in turn produced in his poetry a distillation of all that is New Engla... ...chusetts. 1982 Michalowski, Jay. â€Å"Biography of Robert Frost†. The Robert Frost Web Page. 3 May 2015 http://www.robertfrost.org/indexgood.html Richardson, Mark â€Å"Robert Frost† Modern American Poetry. 5 April 2015. http://www.english.uiuc.edu/maps/poets/a_f/frost/frost.htm Sweeny, John David and Lindroth, James. The Poetry of Robert Frost. New York: Monarch Press, 1965 Van Doren, Mark. â€Å"Robert Frost’s America: June 1951† The Atlantic Online. 5 April 2015. The Atlantic Monthly http://www.theatlantic.com/unbound/poetry/frost/vand.html Wakefield, Richard. â€Å"Thomas Eakins and Robert Frost: â€Å"To be a natural man in a man-made world.† Proquest Online. 5 April 2015. http://proquest.umi.com/pqdweb?TS=1049560053&RQT=309&TS=1049559567&Did=000000056482194&Fmt=3&Deli=1&Mtd=1&Idx =20&Sid=3&Button.x=0&Button.y=0&TS=1049559631&Button.x=0&Button.y=0&TS=1049560082

Australia slashes wheat forecast Essay

In Australia, the commodity markets for wheat hit a formidable loss, as an ongoing drought reduced the predicted crop forecast by a crushing 30%. Australia being the second largest wheat exporter in the world, only behind the United States of America, plays an important role in the distribution of food. Although, in recent years the quantity demanded has risen due to the change in eating habits in China, the growing interest in the use of durum wheat as a bio-fuel, and rising demand for wheat in developing countries. These factors have all contributed to the shortage of wheat, and rising prices of wheat products. For example, pasta in Italy has risen from à ¯Ã‚ ¿Ã‚ ½0.26 per kg to à ¯Ã‚ ¿Ã‚ ½0.45 per kg, and supermarkets may further increase this price by 20% by the end of the year (2007). This rise in price of pasta has created major problems, and protests in Italy, as pasta is Italy’s national dish. Italian’s average consumption of pasta is 28kg a year, making it their staple food. Overall, international wheat prices have risen by a startling 350% in the past five years, and global reserves are at their lowest since the early 1980’s causing geopolitical stress in terms of shortage of food. Since the price of wheat, which is a commodity, (Homogenous goods that are raw materials in critical industries)1 has risen dramatically over the past 5 years, governments across the world should (in a graphical sense) try to shift the demand curve left. The demand (the quantity of goods and services that consumers are willing and able to buy at all prices, for a given time period, ceteris paribus)2 for wheat has been going up, but due to the supply shock (in unplanned change in supply usually occurring because of changes in weather conditions or an external change outside the control of the company or economy)3 – the drought in Australia – the supply (the quantity of goods and services that producers are willing and able to produce for a given time period, ceteris paribus)4 of wheat has decreased dramatically, which has caused a shortage (A deficiency in amount; an insufficiency)5 of it on the global market. Shifting the demand curve left can be done though manipulating the non-price determinants of demand for wheat. Some realistic options of doing this are: the Italian government can reduce taxes to give people a higher income (buy less pasta), the Chinese government can increase income taxes to lower people’s income (buy less meat), negative advertising of wheat and lowering the price of substitutes for wheat (buckwheat, rice, soy products, or other grains). In Italy, since pasta is an inferior good (Items for which an increase in income results in a fall in the amount bought e.g. bread, linoleum and coal)6, in theory people should buy less of it if their incomes rise. In China, since eating habits are changing to eating more meat, farmers are feeding their livestock more wheat for them to grow. By decreasing the Chinese people’s income, they will automatically buy less meat (normal good – Goods to which the general law of demand tends to apply)7. Also, negative advertising of wheat will dissuade people from buying wheat, and will thus push people to buy a wheat substitute, which will be even more of an incentive if the prices of the substitutes are lower than wheat. Also, the demand for wheat used as a bio-fuel can be solved by using other substitutes, such as experimenting with different bio-fuels, like corn. Therefore, the price of wheat can and should be lowered through decreasing the demand for the commodity, as the marginal social benefit of feeding people, has more weight compared to the marginal social costs of the governmental costs of increasing incomes, and lowering prices of substitutes. Shifting the supply curve to the right through the use of a buffer stock scheme (A buffer stock scheme is a form of intervention to try to stabilize the price of a commodity. Stocks of the commodity are kept and sold when the price is high to try to reduce it. When the price is low further stocks of the commodity are bought)8 will be too difficult, or impossible as the reserves of wheat are very low. In short, there would be no other alternatives to fully rectify the shortage, other than rationing, which would still keep some people hungry as there is a shortage. 1 Notes: Commodity Markets – 29th September, 2008 2 Notes: The Law of Demand – September 17th, 2008 3 http://www.bized.co.uk/cgi-bin/glossarydb/browse.pl?glostopic=0&glosid=1213 4 Notes: The law of Supply – September 24th, 2008 5 http://www.answers.com/topic/shortage 6 http://www.bized.co.uk/cgi-bin/glossarydb/browse.pl?glostopic=0&glosid=623 7 http://www.bized.co.uk/cgi-bin/glossarydb/browse.pl?glostopic=0&glosid=680 8 http://www.bized.co.uk/cgi-bin/glossarydb/browse.pl?glostopic=0&glosid=1121

Evolution And Evolution Of Natural Selection - 1826 Words

i. Evolution refers to change over time due to natural selection as organisms adapt and diverge to produce multiple descendant species (Huxley L., Walter M., 2005, p. 698). Two pillars which form the basis of all current knowledge of evolution originate from the historical record of evolutionary change, fossil record and the study of the process of evolutionary change, specifically the effect of natural selection. Recent developments in science, including molecular and developmental biology, have greatly contributed to the understanding of biological diversity and how evolution has changed multiple species, particularly the human species (Losos J., 2014, pp. 3). ii. The concept of natural selection was partially introduced by naturalist Charles Darwin in 1859 when he proposed and provided scientific evidence to describe evolution as the idea that all species have evolved over time from common ancestors through the process of natural selection. To survive in a particular environment, Darwin’s theory proposes that natural selection is the mechanism where organisms must possess attributes that increase their chance of survival in that environment (Chidrawi G., Robson M., Hollis S., 2010, pp 114). Therefore, there will be a tendency for these attributes to be perpetuated and other less appropriate attributes to be lost from the population over successive generations (Huxley L., Walter M., 2005, pp. 698, 704). iii. Fossils are the remains of dead plants and animals that have notShow MoreRelatedEvolution Of Natural Selection Evolution1005 Words   |  5 PagesNatural Selection-Evolution Natural selection is the evolutionary process through which factors in the environment exert pressure, favoring some individuals over others to produce the next generation. Charles Darwin (1809-1882) formulated this theory that has stood the test of time. Natural selection is important to anthropology for understanding how species change. 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