SCIENCE TRIBUNE Thursday, March 2, 2000, Chandigarh, India
 

Nanotechnology: A new world of matter
NOW that nanomania has gripped researchers worldwide, nanotechnology, which deals with matter in the scale of one-billionth of a metre (nanometre), is being considered as the harbinger of a new realm of matter with unusual and unique properties.

Cybersurfing with Amar Chandel
Analyse nuclear-weapons problem
The nuclear spectre is the biggest threat before the world today. Obviously there is also tremendous quest for knowledge on the subject. Most of this can be found under one roof at www.nukefix.org.

Science Quiz
by J. P. Garg

Carbon nanotubes
CARBON NANOTUBES — tiny tubes about 10,000 times thinner than a human hair — consist of rolled up sheets of carbon hexagons.

   
 


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Nanotechnology: A new world of matter

NOW that nanomania has gripped researchers worldwide, nanotechnology, which deals with matter in the scale of one-billionth of a metre (nanometre), is being considered as the harbinger of a new realm of matter with unusual and unique properties.

The technology throws open a wide range of research fields that include nanostructures, nanocomposites, nanowires, nanocrystalline powders, mesoporous material (material having pore sizes in range of 2-50 nanometres), and nanostructured coatings and devices.

But why so much of interest in the nanometer regime?

As chemistry professor Moungi G Bawendi of Massachusetts Institute of Technology (MIT) puts it, solutions of semiconductor nanoparticles fluoresce in a rainbow of different colours depending on the size of the particles. Individual particles behave in other unusual ways like winking on and off, that are not seen in bulk materials.

Also nanoscale particles have a very high surface-to-volume ratio, which can enhance catalytic and other properties.

Furthermore, the bulk behaviour of materials can be dramatically altered by controlling their nanostructure, which can lead to greatly improved performance.

Many nanostructured materials have already been commercialised, in areas like printing, sunscreens, photography and pharmaceuticals. Other potential applications are being studied or developed.

Thin titanium dioxide (TiO2) coating is one commercially used nanoparticle-based material that has self-cleaning antifouling, antifogging and sterilising properties.

Jointly developed by researchers of Tokyo University and Hashimoto’s Research Centre in Japan, the nanocrystalline coating contains TiO2 particles smaller than 20 nanometres (nm), which results in a transparent film that can be applied to ceramics, glass, plastics, polyvinyl chloridecoated fabrics (used for tents), paper, and other materials.

TiO2, a well-known photocatalyst, absorbs ultraviolet light and can oxidise organic compounds at room temperature. Thus, when a TiO2 film is deposited on the glass covers of lighting fixtures used inside an expressway tunnel, the carbonaceous grime that otherwise accumulates on these glass surface is decomposed.

The photocatalytic effect may also account for the finding that bacteria are destroyed on TiO2 located ceramic tiles, making such tiles attractive for hospital operating rooms.

TiO2-coated building tiles can be used to make self-cleaning buildings and self-cleaning paints for automobiles. Auto giant Nissan is already selling Cima, a luxury car, with TiO2-coated side-view mirrors that resist fogging and Toyota is adopting a similar mirror for its model Corolla.

Nanoscale particles also have attracted great interest for their optical properties. Researchers at Nippon Paint Co. in Neyagawa, Japan have been exploring the use of gold and silver colloidal dispersions as paint colorants.

Colloidal gold is well known as a red colorant for glasses. The aim of the researchers was to reproduce this elegant and stable colouring in plastic materials, including paint films.

Compared with ordinary paints, the colloidal paints, because of their small particle size, offer higher transparency and a greater “flip-flop effect” — the colour of the painted surface appears lighter when viewed in direct sunlight and darker when viewed in the shade.

As gold-based paint will be more expensive than conventional paints, so its use may be limited to luxury cars and other high-end applications.

A group of minerals called zeolites which have pore sizes smaller than two nanometres have found widespread use as adsorbents, ion exchangers and heterogenous catalysts for small molecules. Heterogenous catalysts act at the boundary of any two of the three phases of matter — solid, liquid and gas.

A group of MIT scientists are involved in the study of bismuth nanowire arrays.

Nanowire systems are of great interest because of their potential applications in electronic and optical devices.

Bismuth nanowire has unique properties such as high electronic mobility and low thermal conductivity, and is the material of choice for studying new phenomena related to electronic structures.

Bismith nanowire arrays could be useful for thermoelectric refrigeration, in which cooling is produced directly from electrical energy. Bismuth in the bulk is not a promising thermoelectric material, but its prospects improve markedly if it is fashioned into arrays of uniform nanowires, MIT researchers suggest.

An MIT researcher has reported that studies of the electrical resistance, magneto resistance, and optical properties of bismuth nanowire have revealed many usual effects. Measurements provide strong evidence that bismuth in the form of a nanowire makes a transition from a semimetal to a semiconductor because of a phenomenon called “quantum confinement effect.”

The results hold promise for thermoelectric applications. But the immediate objective is to improve the odds of success by making slightly thinner nanowires in the range of five to 10 nanometres.

A group of researchers at Sandia National Laboratories and University of New Mexico have jointly developed a rapid and efficient method for growing layered nanostructured films similar to nacre — the hard pearly and iridescent substance forming the inner layer of a mollusk shell.

Nacre is a nanocomposite consisting of alternating layers of calcium carbonate and a biopolymer. Its laminated structure is remarkable for its strength, hardness, and toughness.

The architecture of the new transparent film coating is similar to that of nacre, although chemically it is quite different. Its characteristics, such as hardness, toughness and strength, would be useful for automotive finishes or other abrasion-resistant coatings.

A lot more may come up in the future with obsessed researchers trying to further reduce the scale of nanotechnology. (PTI)
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Cybersurfing with Amar Chandel
Analyse nuclear-weapons problem

The nuclear spectre is the biggest threat before the world today. Obviously there is also tremendous quest for knowledge on the subject. Most of this can be found under one roof at www.nukefix.org. You can access hundreds of articles that appeared in various newspapers and magazines on the subject during 1999 and earlier years. These are categorised according to the subject area. You can get quite a bit of information about the nuclear programmes of India and Pakistan.

It is often asserted that nations will learn to live with nuclear weapons and that they will reach a state of relative safety. This presumes some kind of learning curve. In the graphs attached to Nukefix’s learning curve page, you can model and see the outcomes for two “learning” curves (accidental and wilful use).

Nukefix screen snapshots show probability of a nuclear use, effects of proliferation, START II treaty, deterrence, simultaneous detonations etc. Another section contains original pictures and much new information (see photo alongside).

One can get answers to questions such as what is the chance of a nuclear use occurrence during one’s remaining lifetime and one’s children’s lifetime? What is the health risk?

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Many web engines answer your various questions on any topic under the sun. However, there is an impersonal coldness about this exchange. A website, www.xpertsite.com , goes a step further. It has a large number of experts on various subjects like health, art and leisure, home and garden, money and services, entertainment, education, society and culture, science, etc. Once you post a question, you are given a long list of similar questions posed by others before you. If your query matches any of these, you can read it to get the answer. If not, then your question in posted on the Net. Soon enough, one or the other experts comes up with a reply.

If you have the time, expertise and inclination, you too can register as an expert and offer to answer questions in your field of specialisation.

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For those who have a taste for the unusual, www.strange pages.net has a lot to offer. It deals with such subjects as forensics, serial crime, cults and crime prevention. For the astrology buffs, there are horoscopes, predictions, tarot cards and what not. You can also download astrology softwares.

For $25, one can download a software, NetDetective 2000, through which you can find out anything about yourself, your boss, friends or family members. It even claims to give you the details that the FBI has about you. Apparently, it is meant for use in the USA.

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Music lovers can download a lot of free stuff from www.audiohighway.com and play the music either on Media Player or Real Player. The hottest singers these days are Carlos Santana, winner of a whopping eight Grammy awards, and Christini Aguilera, who won the Grammy for the best new female artist of the year.

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Reports of hacking notwithstanding, e-commerce is picking up even in India. For the lay computer buffs, one interesting website is www.koolmaal.com. Here one can buy and sell a lot of material. Among the many items currently available for auction are a 100-year-old Jamini Roy painting. The reserve price: Rs 4 lakh.

One has to submit one’s name, address and e-mail etc to become a seller. It is not clear how one can check the authenticity and the actual condition of items available on sale. The information given about these is sketchy at best.
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Science Quiz
by J. P. Garg

1. Who is the leader of “CHIPKO Movement” in India? What does this movement mean?

2. NASA scientists have recently found that galaxies (including our own Milky Way) keep on recycling the material of their stars through a violent series of processes. The discovery has been made using a space probe FUSE which was put into orbit above the earth only last year. What is the full name of this space probe?

3. A computer can be used to analyse a complex process or operation in order to improve efficiency. What is this method of analysis called?

4. Integrated circuits made from proteins or organic polymers may revolutionise technology industry in the near future. What is this type of integrated circuit called and which technology are we talking about?

5. This camera has 30 lenses which can simultaneously capture images from 30 different points of view. What is this camera called?

6. The tilt of the Leaning Tower of Pisa in Italy was recently reduced by 3 cm. Why is this tower famous in physics?

7. Radio Frequency Cathether Ablation is a new technique to treat patients having abnormally rapid beats and rhythms in some parts of the heart. What are the main symptoms of this disease?

8. What is the technique of dating (estimating time) by examining the characteristic pattern of growth rings in trees called?

9. What term is used for the sum of the internal energy of a system and the product of its pressure and volume? What does this sum represent?

10. We know that haemoglobin is a protein present in red blood cells. What function does this protein perform? Who discovered its structure?

Answers

1. Sunder Lal Bahuguna; People embrace the trees to save them from being cut 2. Far Ultraviolet Spectroscopic Explorer 3. Systems analysis 4. Biochip; biotechnology 5. Array camera 6. Galileo Galilei performed his famous experiment on falling bodies from this tower 7. Dizziness, fainting and breathlessness 8. Dendochronology 9. Enthalpy; heat energy of the system 10. It carries oxygen to all cells in the body; British biochemist John Kendrew in 1960.
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Carbon nanotubes

CARBON NANOTUBES — tiny tubes about 10,000 times thinner than a human hair — consist of rolled up sheets of carbon hexagons.

Discovered in 1991 by researchers at NEC, they have the potential for use as minuscule wires or in ultrasmall electronic devices.

To build those devices, scientists must be able to manipulate the nanotubes in a controlled way.

IBM researchers using an atomic force microscope (AFM), an instrument whose tip can apply accurately measured forces to atoms and molecules, have recently devised a means of changing a nanotube’s position, shape and orientation, as well as cutting it.


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