Archive for February, 2013

The Tunguska Event - Meteorite or Comet ?

 The Tunguska Giant Explosion

A meteorite is a meteoroid (a solid piece of debris from such sources as asteroids or comets) originating in outer space that survives impact with the Earth’s surface. A meteorite’s size can range from small to extremely large. Most meteorites derive from small astronomical objects called meteoroids, but they are also sometimes produced by impacts of asteroids.

When a meteoroid enters the atmosphere, frictional, pressure, and chemical interactions with the atmospheric gasses cause the body to heat up and emit light, thus forming a fireball, also known as a meteor or shooting/falling star. The term bolide refers to either an extraterrestrial body that collides with the Earth, or to an exceptionally bright, fireball-like meteor regardless of whether it ultimately impacts the surface.

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Nano Welding

Nano Welding Reviews

US researchers have found a new way to weld together metal nanowires - simply by bathing them in white light. The finding could offer a new way to fabricate transparent nanowire meshes for electronic applications in areas such as touchscreens and organic photovoltaics.

Erik Garnett and colleagues at Stanford University used a technique called the polyol process to synthesise silver nanowires 30-80nm in diameter and 3-10µm long. The process results in nanowires that are coated in a molecular sheath of polyvinylpyrrolidine (PVP). The nanowires were deposited on a surface randomly by dropping or spraying. This resulted in many of the wires lying over one another in a criss-cross pattern. Due to the layer of PVP where the nanowires cross, a gap of about 2nm exists between them.

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Advanced Ceramics an Introduction

Ceramics an Introduction

The 20th century has produced the greatest advancement in ceramics and materials technology since humans have been capable of conceptive thought. As the limits of metal-based systems are surpassed, new materials capable of operating under higher temperatures, higher speeds, longer life factors and lower maintenance costs are required to maintain pace with technological advancements.

Metals, by virtue of their unique properties: ductility, tensile strength, abundance, simple chemistry, relatively low cost of production, case of forming, case of joining, etc. have occupied the vanguard position in regard to materials development. This combination enables large shapes to be made; the Space Shuttle is a typical example of the application of advanced materials and an excellent example of the capability of advanced materials.

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