Mostafa El-Sayed

August 25, 2011 by · Leave a Comment 

By Syed Aslam

el-sayedMostafa  El-Sayed was born in the year 1933  at Zifta, Egypt. He graduated  with bachelor of  science degree from  Ein Shams University, Cairo,  and completed PhD. in chemistry at Florida State University, Tallahassee, Florida in1958. He held Research Associate  positions at Harvard, Yale and the California Institute of Technology. He was appointed to the faculty of the Department of Chemistry and Biochemistry, University of California at Los Angeles,  where he worked till 1994.  At present he is the Julius Brown Chair and Regents Professor and Director of the Laser Dynamics Laboratory at the Georgia Institute of Technology.

Dr. Mostafa El-Sayed  have contributed to many areas of physical and materials chemistry research, including the development of new techniques such as magnetophoto selection, picosecond Raman spectroscopy and phosphorescence microwave double resonance spectroscopy. Using spectroscopic techniques, they have been able to answer fundamental questions regarding ultrafast dynamical processes involving molecules, solids and photobiological systems. His work earned him a 2007 US. National Medal of Science award in Chemistry for his seminal and creative contributions to our understanding of the electronic and optical properties of nano-materials and to their applications in nano-catalysis and nano-medicine. His work has opened a brand new method to understand nanoparticles which can be used in nano-technology. 

Dr. Mostafa El-Sayed’s group were the first to synthesize metallic nanoparticles of different shape. It would be quite profitable if one can determine the type of reactions each shape would catalyze. Selectivity in catalysis saves a great deal of energy and money in reducing the need for exhaustive and expensive separation costs. Different nanocrystal shapes have different facets and so it can be used for different  catalytic functions. The El-Sayed’s group is also studying different techniques to stabilize the nanocrystal shapes, which can be used for a particular catalytic effect.  

Mostafa  El-Sayed is an internationally renowned nanoscience researcher whose work in the synthesis and study of the properties of nanomaterials of different shape may have applications in the treatment of cancer. He has a spectroscopy rule named after him, the El-Sayed rule. He has over 300 publications in the areas of spectroscopy and molecular dynamics. He uses short pulsed lasers to understand relaxation, transport and conversion of energy in molecules, in solids and in photosynthetic systems. He supervised the research of 50 PhD. students, 30 postdoctoral fellows and 15 visiting professors. Among his other many honors are the 2009 Ahmed Zewail Prize in Molecular Science.

Aslamsyed1@yahoo.com

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Wings Explained

April 1, 2010 by · Leave a Comment 

tufail

A wing is a surface used to produce lift for flight through the air or another gaseous or fluid medium. The cross-sectional shape of a wing is referred to as an airfoil. The word originally referred only to the foremost limbs of birds, but has been extended to include the wings of insects, bats, pterosaurs, and aircraft. The term is also applied to an inverted wing used to generate down-force in auto racing.

A wing’s aerodynamic quality is expressed as a Lift-to-drag ratio. The lift generated by a wing at a given speed and angle of attack can be 1-2 orders of magnitude greater than the drag. This means that a significantly smaller thrust force can be applied to propel the wing through the air in order to obtain a specified lift.

The science of wings is one of the principal applications of the science of aerodynamics. In order for a wing to produce lift it has to be at a positive angle to the airflow. In that case a low pressure region is generated on the upper surface of the wing which draws the air above the wing downwards towards what would otherwise be a void after the wing had passed. On the underside of the wing a high pressure region forms accelerating the air there downwards out of the path of the oncoming wing. The pressure difference between these two regions produces an upwards force on the wing, called lift.

The pressure differences, the acceleration of the air and the lift on the wing are intrinsically one mechanism. It is therefore possible to derive the value of one by calculating another. For example lift can be calculated by reference to the pressure differences or by calculating the energy used to accelerate the air. Both approaches will result in the same answer if done correctly.

A common misconception is that it is the shape of the wing that is essential to generate lift by having a longer path on the top rather than the underside. While wings with this shape are always used in subsonic aircraft and sailing, symmetrically shaped wings can also generate lift by having a positive angle of attack and deflecting air downward. The symmetric approach is less efficient, lacking the lift provided by cambered wings at zero angle of attack.

The common aerofoil shape of wings is due to a large number of factors many of them not at all related to aerodynamic issues, for example wings need strength and thus need to be thick enough to contain structural members. They also need room to contain items such as fuel, control mechanisms and retracted undercarriage. The primary aerodynamic input to the wing’s cross sectional shape is the need to keep the air flowing smoothly over the entire surface for the most efficient operation.

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