As this surface area to volume ratio increases with decreasing size, a general trend is for smaller particles to transfer heat more effectively than larger particles. If you take the same volume of particles, but instead compress it into one large particle, then that large particle will warm slowly. If you place a large quantity of small cold particles in a warm body of water, the particles will heat quickly. Since thermal conduction through volume is a function of surface area, particles with large ratios of surface area to volume are able to change temperature very quickly. But how does this relate to nanoparticles? As a particle becomes very small, the ratio of the particle’s surface area to its volume increases very rapidly. A larger contact surface area leads to faster conduction. Conductive heat transfer from one object to another depends on the area over which the thermal transfer takes place. This is an example of thermal energy transfer via conduction. Placing your entire hand over the top half of the ice cube increases the melting rate, and placing the ice cube in your hand and closing your fist further increases the melting rate. If you place the ice cube on a chilled dish and touch the ice cube with one finger, the cube will melt, but probably fairly slowly. Clearly, you are (hopefully!) warmer than the ice cube. Consider the process of transferring the thermal energy of your body from your hands to an ice cube. One important implication for our discussion is the flow of thermal energy. Visionary researchers are now looking into ways in which these interesting properties may make nuclear power plants more efficient. This has far reaching implications for how particles interact with light, heat, and other particles. As a sphere shrinks, the ratio of the surface area to the volume grows. Some of these changes are due to how basic properties such as volume and surface area change as an object becomes smaller. Because of their small size, the physical principles governing how particles behave and interact with their environments change. Of course, the Romans did not know they were using nanoparticles in the process of making this glass.īut what makes nanoparticles interesting or unique? The answer to this question depends on the specific material and application, but a few themes persist. Higgitt, Gold Bulletin 40, 270-277, 2007. The effect results from the glass filtering various wavelengths of light differently depending on the various lighting conditions. The result is a glass that appears green when lit from the outside, but red when lit from the inside.I. 737, 元0, 2011. One of the oldest documented applications of nanomaterials dates back to the Lycurgus Cup, a 4 th century Roman glass which was made out of a glass containing gold and silver particles. Some researchers have even discovered signs of nanoscale materials in space.D.A. These objects represent natural materials with significant, and often highly functional, nanoscale features. This includes viruses, the coatings of a lotus leaf, the bottom of a gecko’s foot, and some finely powdered clays. Nanomaterials are not new, and indeed occur naturally all over Earth. This new category of materials has ignited the imaginations of scientists and engineers who envision nanomaterials capable of tackling difficult problems in energy, healthcare, and electronics. To provide a sense of scale, most viruses are a few hundred nanometers in size, most bacteria are a few thousand nanometers in size, and a period at the end of a sentence is about a million nanometers. Hornyak, Fundamentals of Nanotechnology, 2009. – and researchers are now implementing these materials in areas as disparate as neuroscience and environmental remediation. The past twenty five years have ushered in an era of nanomaterials and nanoparticles – objects with at least one dimension between 1 and 100 nanometersG.L. The race to synthesize, engineer, test, and apply new nanoscale materials for solving difficult problems in energy and defense is in full swing. This article will briefly introduce nanomaterials and discuss ways in which some of these particles may make nuclear power plants more efficient. However, a class of very small particles may be gearing up to lend a helping hand in making power plants more efficient and less costly to operate. Energy Information Administration, Annual Energy Review, 2011. and in the process consume enormous quantities of water. They provide approximately 19 percent of U.S. Nuclear power plants are large, complex, and expensive facilities.
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