Fiber optic endoscope

To view objects which are located at inaccessible regions, fiber optic endoscopes are used. This device is an important tool for a medical practitioner for diagnosis. Fine examination of internal organs of the human body can be done by this device. Bronchoscope is an endoscope which is used to inspect the interior of upper portion of patient’s body. Normally an optical endoscope is composed of two bundles of fibers mounted co-axially in a tube. Through one bundle light is sent and the light reflected from the internal organs is received through the other bundle. Separation of the bundles is very easy to execute since they are flexible. A light source is fitted to one bundle and the other bundle is fitted to eyepiece through which the surgeon can view the internal parts. The internal parts can be displayed on a computer monitor. Colonoscope is another example of fiber optic endoscope.

Methods of preparation of nanomaterials

There exist many methods for the preparation of nanomaterials. These methods are broadly classified into two: top-down approach and bottom-up approach. Milling (mechanical grinding) and lithography are examples of top-down methods. . During milling, balls in the vial impart energy to powder material splitting them further to nanoscale. Lithography deals with the nanoelectromechanical systems which can be developed by using light, electron beam or ion beam. Wet chemical methods, plasma chemical methods, sol gel methods, physical vapour deposition, chemical vapour deposition, sputtering, Laser ablation, Molecular beam epitaxy, thermolysis, electrodeposition, Self assembly method etc are examples of bottom-up methods.

Introduction to nanoscience and nanotechnology

Nanoscience is the study of atoms and molecular structures whose size, at least in one dimension is between 1-100 nm. Nanotechnology is the design and fabrication of devices using such nanostructures. Nanomaterials exhibit properties strikingly different from those of bulk materials. Both surface effects and size effects plays crucial role in the properties of nanomaterials. The state of matter around nanosize is referred to as mesoscopic state. The physics of nanotechnology is also called as mesoscopic physics. Fullerenes, carbon nanotubes and nanowires are examples of inorganic nanomaterials. Each fullerene molecule comprises of sixty carbon atoms arranged in globular shape. Nanowires are arrangements in one direction made of silicon, zinc oxide and various metals. Artificially synthesized DNA strands are examples of organic nanomaterials.

Hydrogen Over-voltage

In some cathodic reactions, the reduction of the electro-active materials occurs in several steps. Polarization may occur if any of these steps is slow and irreversible. This polarization is termed as over-voltage and may take place at one or both the electrodes. Over-voltage is actually the extra voltage to be applied over and above the theoretical decomposition potential of an electrolyte to start the electrolysis of the electrolyte. There exist many parameters which affects the over-voltage. They are nature and physical state of the electrodes, nature of the material deposited, current density, temperature and nature of electrolyte. Hydrogen over-voltage plays an important role in the electrodeposition of metals.