Nucleic Acids
Introduction The first isolation of what we now refer to as DNA was accomplished by Johann Friedrich Miescher circa 1870. He reported finding a weakly acidic substance of unknown function in the nuclei of…
DNA: Damage Types and Repair Mechanisms
Introduction to DNA Damage and Repair: DNA is a highly stable and versatile molecule. Though sometimes the damage is caused to it, it is able to maintain the integrity of…
What are monoclonal antibodies?
Monoclonal antibodies (mAb or moAb) are identical immunoglobulins, generated from a single B-cell clone. These antibodies recognize unique epitopes, or binding sites, on a single antigen. Derivation from a single B-cell…
Environmental Diversity of Microbes
Microbes are ubiquitous on Earth and their diversity and abundance are determined by the biogeographical habitat they occupy. The microbial world encompasses most of the phylogenetic diversity on Earth, as…
Nutritional Requirements of Cells
Every organism must find in its environment all of the substances required for energy generation and cellular biosynthesis. The chemicals and elements of this environment that are utilized for bacterial…
Types of boilers
Boilers can be classified as follows: 1. According to the flow of water and hot gases – fire tube (or smoke tube) and water tube boilers. In fire tube boilers,…
Simple Harmonic Motion
What is Simple Harmonic Motion (SHM)? Amplitude, Frequency and Periodic Time of a body moving with SHM? A body is said to move or vibrate with simple harmonic motion (briefly…
Fire Fighting Strategies
Now we know all the constituents of a fire and various kinds of fire-extinguishers. If you have to fight a fire, depending on the circumstances, you have to decide as…
Timing Belts
Belt drives have a major role in rotary power transmission. Just try to peep under the hood of your automobile whether it’s a car or a SUV, you are sure…
Corrosion and Degradation of Materials
Corrosion of Metals The corrosion resistance of metals and alloys is a basic property related to the easiness with which these materials react with a given environment. Corrosion is a natural process that seeks to reduce the binding energy in metals. The end result of corrosion involves a metal atom being oxidized, whereby it loses one or more electrons and leaves the bulk metal. The lost electrons are conducted through the bulk metal to another site where they are reduced. In corrosion parlance, the site where metal atoms lose electrons is called the anode, and the site where electrons are transferred to the reducing species is called the cathode. Pure metals are used in many applications. Copper, for example, is used to make the wire which goes inside electrical cables. Copper was chosen because it can be drawn into long thin wires very easily (it is ductile) and because it is a good conductor of electricity. Pure aluminum can also be used in wiring. It is also used as a cladding material for aluminum alloy substrates. Currently there are 86 known metals. Before the 19th century only 24 of these metals had been discovered and, of these 24 metals, 12 were discovered in the 18th century. Therefore, from the discovery of the first metals, gold and copper, until the end of the 17th century, some 7700 years, only 12 metals were known. Four of these metals, arsenic, antimony , zinc and bismuth , were discovered in the thirteenth and fourteenth centuries, while platinum was discovered in the 16th century. The other seven metals, known as the Metals of Antiquity, were the metals upon which civilization was based. These seven metals are Gold, Copper, Silver, Lead, Tin, Iron,Mercury.
