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Biology 代写:An Introduction To Nanoscience And Nanotechnology

1.4.4 Environmental Protection

Nanotechnology has the potential to benefit the environment through pollution treatment and remediation as any waste atoms could be recycled, since they could be kept under control. This would include improved detection and sensing, removal of the finest contaminants from air, water and soil, and creation of new industrial processes that reduce waste products and are ecofriendly. Airborne nanorobots could be programmed to rebuild the thinning ozone layer. Immense tonnage of excess carbon dioxide in the atmosphere could be economically removed air bone. One of the biggest environmental challenges that humanity faces today is clean water. The potential benefits of nanotechnology also help to remove the finest [i.e. smallest] contaminants from water and air, promoting a cleaner environment and potable water at an affordable cost. Nanoparticles of iron can be effective in the cleanup of chemicals in groundwater because they react more efficiently to those chemicals than larger iron particles.

1.4.5 Agriculture

Nanotechnology will improve agricultural yields for an increased population, provide more economical water filtration and desalination, and improve renewable energy sources, such as solar energy conversion. Nanotechnology has a significant effect in the main areas of the food industry: development of new functional materials, product development and design of methods and instrumentation for food safety and bio-security. Using nanoparticle technology, Bayer has developed an airtight plastic packaging that will keep food fresher and longer than their previous plastics. Nanotechnology will also help to modify the genetic constitution of the crop plants, thereby helping improvement of crop plants. Nanotechnology based plant disease diagnostics help to detect exact strain of virus and stage of application of some therapeutic to stop the disease.

1.4.6 Energy

Energy applications of nanotechnology include storage, conversion, manufacturing improvements by reducing materials and process rates, energy saving and enhanced renewable energy sources. Nanotechnology could help increase the efficiency of light conversion of solar cells by using nanostructures with a continuum of band gaps. Nanotechnological approaches like light-emitting diodes (LEDs) or quantum caged atoms (QCAs) could lead to a strong reduction of energy consumption for illumination. An environmental friendly form of energy is the use of fuel cells powered by hydrogen. The most prominent nanostructured material in fuel cells is the catalyst consisting of carbon supported noble metal particles with diameters of 1-5 nm. Suitable materials for hydrogen storage contain a large number of small nanosized pores. Therefore many nanostructured materials like nanotubes, zeolites or alanates are under investigation.

1.4.7 Nano products/devices

The ability to see nano-sized materials has opened up a world of possibilities in a variety of industries and scientific endeavors. As mentioned earlier, nanotechnology is essentially a set of techniques that allow manipulation of properties at a very small scale and it may help to revolutionize products everywhere, creating a vast array of new products and devices. The promise of these products and devices is tremendous. Nanotechnology can change the nature of almost every manufactured product. Because of this, nanotechnology will have more influence than the silicon integrated circuit, medical imaging, or computer-aided engineering. Amazingly, more than 1000 commercial nanomaterial-based products are available in the market.

The properties of familiar materials are being changed by manufacturers who are adding nano-sized components to conventional materials to improve performance. For example, some clothing manufacturers are making water and stain repellent clothing using nano-sized whiskers in the fabric that cause water to bead up on the surface. Companies are now manufacturing nanoparticles for use in hundreds of commercial products – from crack-resistant paints and stain-resistant clothing, to self cleaning windows and anti-graffiti coatings for walls.

Some examples of nano products/devices:

Exploiting the anti-bacterial properties of nano-scale silver, Smith & Nephew developed wound dressings (bandages) coated with silver nano-crystals designed to prevent infection. Hundreds of products incorporating nanosilver are now on the market, including sheets, towels, appliances, socks, toothbrushes, toothpastes and children’s toys.

Nanoparticles of titanium dioxide (TiO2) are transparent and block ultraviolet (UV) light. Nano-scale TiO2 is now being used in sunscreens and in clear plastic food wraps for UV protection.

Nano-scale particles of hydroxyapatite have the same chemical structure as tooth enamel. Researchers at BASF are hoping to incorporate the nanoparticles in toothpaste to build enamel-like coating on teeth and to prevent bacteria from penetrating. Sangi Co. Ltd. (Japan) has been selling a toothpaste containing nano-hydroxyapatite since 1980.

Nano-Tex sells “Stain Defender” for khaki pants and other fabrics – a molecular coating that adheres to cotton fiber, forming an impenetrable barrier that causes liquids to bead and roll off.

Pilkington sells a “self-cleaning” window glass covered with a surface layer of nano-scale titanium dioxide particles. When the particles interact with UV rays from sunlight, the dirt on the surface of the glass is loosened, washing off when it rains.

BASF sells nano-scale synthetic carotenoids as a food additive in lemonade, fruit juices and margarine (carotenoids are antioxidants and can be converted to Vitamin A in the body). According to BASF, carotenoids formulated at the nano-scale are more easily absorbed by the body and also increase product shelf life.

Syngenta, the world’s largest agrochemical corporation, sells two pesticide products containing nano-scale active ingredients. The company claims that the extremely small particle size prevents spray tank filters from clogging and the chemical is readily absorbed into the plant’s systems and cannot be washed off by rain or irrigation.

Altair Nanotechnologies is developing a water-cleaning product for swimming pools and fishponds. It incorporates nano-scale particles of a lanthanum-based compound that absorbs phosphates from the water and prevents algae growth.

Silicon-based, disposable blood-pressure sensor chips were introduced in the early 1990s by NovaSensor for blood pressure monitoring.

A variety of biosensors are manufactured by various companies, including ACLARA, Agilent Technologies, Calipertech, and I-STAT.

1.5 Risks of Nanomaterials

Although nanotechnology has a significant impact on society, and every sector of economy, nanomaterials may pose new risks to workers, consumers, public and environment. Risks can occur anywhere nanomaterials come in contact with people, animals or environment. Key risks relate to liability, privacy, financing and safety of products. For the health arena, the most immediate concerns are likely the safe and ethical use of nanomaterials. The microscopic size of nanoparticles makes them difficult to be detected and controlled. Researchers, staff, consumers or patients may inadvertently inhale therapeutic products. The models and predictability of these molecular interactions are not yet known. Thus, precautions to avoid inhalation and emergency methods to disable the technology will be needed. Current gloves, masks, and gowns may not provide adequate protection, creating a need for new evaluation research, new protective equipment, and a calculation of the associated costs before the technology is widely used. Only a few research findings are available about the safety of nanomaterials. Researchers found that nanoparticles can provoke increased inflammatory responses and potentiate the effect of medications.

People have started to raise serious questions about the possible impact of nanomaterials on human health. The small size of nanoparticles can give them greater access to body tissues and organs than larger particulates. Animal studies have reported that some inhaled nanomaterials pass easily from the nose directly into the brain via olfactory neurons, and from lungs into the blood stream. Once nanomaterials enter the body, the larger surface area of nanomaterials per unit of mass makes them more chemically reactive than their normal-scale counterparts, and therefore more likely to interact with biological molecules. Cell studies indicate that some nanomaterials may interact with cell DNA, cause inflammation and oxidative damage, and impair cell function. Engineered modifications to nanomaterials, such as surface coatings, can alter a material’s solubility, chemical activity, toxicity, and other properties, providing an opportunity to reduce the risks associated with a material early in its design. Although there is a paucity of toxicity data specific to engineered nanomaterials, the hazards of nanosize air pollutants are well documented. Particulate matter less than 10μm (10,000 nm) has been linked to increased lung cancer and cardiopulmonary disease. While all particulate air pollution is hazardous, smaller inhaled particles have long been known to be more damaging to body tissues than larger particles, inducing inflammation and tissue damage. The risks are especially high among individuals with pre-existing heart and lung ailments, including asthma and chronic obstructive pulmonary disease, suggesting that millions of people with these conditions may be vulnerable to the hazards of inhaled nanomaterials. A variety of nanomaterials has the capacity to cause tissue and cellular damage by causing oxidative stress. Report shows that Bulkyballs caused oxidative damage to brain and liver cells in a study in largemouth bass. Other nanoparticles have also been shown to cause oxidative stress in skin cells and liver. Oxidative stress may also cause damage to lung tissue. These kinds of disquieting behaviours have generated an urgent need for more research about the safety of nanomaterials.

The ethical use of nanomaterials is a major area of concern for health care providers. Obviously, guidelines along with the risk possible with nanoamaterials should be created to preserve human dignity and integrity. Much of the current focus is to determine what research should be done about the risks of nanomaterials. Nanotechnologists have published five grand challenges for the safe handling of nanotechnology. They are,

develop instruments to assess exposure to engineered nanomaterials in air and water,

develop and validate methods to evaluate the toxicity of engineered nanomaterials,

develop models for predicting the potential impact of engineered nanomaterials on the environment and human health,

iv) develop robust systems for evaluating the health and environmental impacts of engineered nanomaterials over a human lifetime, and

v) develop strategic programmes that enable relevant risk-focused research.

Further Reading

Bhusion B, Handbook of nanotechnology (NY: Springer – Verlag Berlin Heidelberg, 2004).

Borm PJA, Particle and Fibre Toxicology 3, 11 (2006).

Dockery DW and Pope CA, Annual Revision Public Health, Vol. 15, pp.107-32 (1994).

Dockery DW and Stone PH, New England Journal of Medicine, Vol. 356, No. 5, pp. 511-12 (2007).

Drexler KE, Nanosystems: Molecular Machinery, Manufacturing, and Computation (John Wiley & Sons, Inc.: NY, 1992).

Drexler KE, Proc. Natl Acad. Sci. USA 78 5275-5278 (1981).

Feynman RP, Engineering and Science Magazine of Cal. Inst. of Tech., 23, 22, (1960).

Feynman RP, J. of Microelectromechanical Systems, 2,1,4, (1993).

Iijima S, Nature 354, 56 (1991).

Luth H, Surfaces and Interfaces of Solid Materials (Heidelberg: Springer, 1995).

Moore G, Electronics, 38, No. 8 (1965).

Moore G, IEDM Technical Digest 11 (1975).

Peters A, Dockery DW, Heinrich J, and Wichmann HE, European Respiratory Journal Vol. 10, No. 4, pp. 872-9 (1997).

Poole CP and Owens FJ, Introduction to Nanotechnology (John Wiley & Sons, 2006).