Molecule matters Dinitrogen

Dinitrogen (N₂) is a very stable and inert molecule due to the formation of a triple bond between the two atoms. Surprisingly isoelectronic molecules are quite reactive making dinitrogen very useful and unique.     

Evolution of the atmosphere and oceans: Evidence from geological records 3. Evolution of the early oceans

The proto-ocean owes its origin to condensation of water vapour from the proto-atmosphere. Much of this ocean was lost to subsequent giant impacts. The water of the modern ocean is largely secondary, delivered by cometary impacts soon after the Moon-forming event. The early ocean had low dissolved O₂ and SO ₄ ²⁻ but had high pH and dissolved Fe²⁺.     

Silicon photonics Silicon Raman lasers

The increased use of optoelectronic devicessuch as TV screens and computer monitors in everyday life, calls for a material on which integration of all circuits may be performed. Silicon, the most widely used material in electronics, has limited application in optoelectronics due to its poor light emission property. In this article, the need for silicon photonics in present day ICs, and communication, the reason for its inefficient light emission, and recent breakthrough in the form of Si Raman laser are discussed.     

Fire synthesis Preparation of alumina products

The novel ‘solution combustion method’ or ‘fire synthesis’ has been used to make high temperature synthesised ceramic materials. The process, which can be initiated at low temperature, is self-propagating and gas-producing. Fine-particle alumina and its related oxides can be easily prepared in bulk by the redox mixture method.     

Mangroves The most fragile forest ecosystem

Mangroves, an exclusive group of plants with remarkable ecological importance, inhabit mostly the zones washed by the back and forth movement of tides. They are disappearing rapidly from their natural habitat due to various reasons. Mangroves create a unique ecological environment that is composed of rich assemblages of species. Economic importance of mangroves is also noteworthy.     

The Indian monsoon 5. Prediction of the monsoon

In this article we first consider the importance of prediction of the monsoon, and events such as the intense rainfall event over Mumbai in July 2005. We then discuss how meteorologists make short-, medium-, and long-range forecasts and the concept of the limit of predictability in a chaotic system such as the atmosphere. Problems and prospects of prediction on different time-scales are discussed by using one example of short-range forecasts and the prediction of the monsoon by dynamical and statistical methods. Finally we consider measures of the skill of a forecast and how high the skill has to be for it to be useful for applications.     

The Freudenstein equation Design of four-link mechanisms

Ferdinand Freudenstein is widely acknowledged to be the father of modern kinematics of mechanisms and machines. His PhD thesis in 1954 and subsequent research papers by him and his students have influenced academic and industrial research, teaching and practice related to the analysis and design of mechanisms and machines throughout the world. In this article, we revisit Freudenstein’s thesis and the equation named after him. The Freudenstein equation results from an analytical approach towards analysis and design of four-link mechanisms which, along with its variants, are present in a large number of machines used in daily life.     

Willis H carrier Father of air conditioning

Willis H Carrier, the Father of Air Conditioning, placed the science of air conditioning on a firmscientific basis in the year 1911, in his paper ‘Rational Psychrometric Formulae’ — widely known also as the ‘Magna Carta of Psychrometrics’. This paper was presented at the annual meeting of American Society of Mechanical Engineers (ASME). The centenary of this historic event happens to be the past year 2011. Amongst his many achievements are his contributions to development of the Psychrometric Chart (which remains essentially the same as the chart presentedmore than a century ago), the Law of Constant Dew-Point Depression, Dew-Point Control and the invention of the Centrifugal Refrigeration Machine.     

Concept of green chemistry Redesigning organic synthesis

Green chemistry is the utilization of a set of principles that will help reduce the use and generation of hazardous substances during the manufacture and application of chemical products. Green chemistry aims to protect the environment not by cleaning up, but by inventing new chemical processes that do not pollute. It is a rapidly developing and an important area in the chemical sciences. Principles of green chemistry, developments in this field and some industrial applications are discussed.     

Irving Langmuir A pioneering industrial physical chemist

This is a biography of one of the most famous industrial chemists of the last century. Irving Langmuir showed that developing new devices leads to fundamental work of the highest order. Langmuir was the first industrial chemist to get the Noble Prize.