Molecular matters van der Waals molecules: 1. History and some perspectives on intermolecular forces

van der waals introduced his equation of state in 1867 modifying the ideal gas equation. His equation had two constants a and b, which accounted for the fact that molecules have attractive forces and finite size. The constant a accounted for the attractive forces, the nature of which was not outlined by van der waals. This series of articles will discuss about the nature of intermolecular forces

Molecule matters van der Waals molecules: 2. Noble gas clusters are London molecules!

In Part 2 of this series, we discuss homo- and hetero-nuclear noble gas dimers. Experimental and theoretical results for dimers containing He, Ne, Ar, Kr and Xe are reviewed. These dimers are bound by London dispersive forces, which is one component of the van der Waals or intermolecular forces. Though these are usually called van der Waals complexes or van der Waals molecules, these dimers may be more appropriately called London molecules. Helium dimer is a particularly interesting case with the equilibrium internuclear distance estimated to be about 50 Angstrom

Parambumalai (Piranmalai) in the Liberation Struggle

Parambumalai, which days back to the Sangam period, is now known as Piranmalai. It was a separate area from the rule of the Chera, Chola and Pandya empires. Sivagangai and Ramanathapuram were part of the princely state during the Indian Liberation War. The battlefield where the heroes Maruthupandiyar, Velunachchiyar, Veerapandiya Kattabomman and Oomaithurai fought valiantly is Piranmalai. There is a huge fort and an armoury here. History has shown that the greatest wars against the British army took place here. Rocket launchers, artillery, guns, etc. had been used in combat. The Battle of Piranmalai has been hailed as the foremost and most important war in the history of the Indian liberation struggle. T hese histories are scattered without being fully compiled. The English general Welsh’s notes, military records, and folk songs are now updating these histories. These will help to open the unknown pages of the history of Indian independence struggle. Thus, the unknown Piranmalai will become as important as other symbols of India's liberation struggle

Molecule matters van der Waals molecules: 3 - Rg•••HF complexes are Debye molecules!

In this article, Debye's contributions to understanding van der Waals attractive forces, specifically, dipole-induced dipole interaction, is discussed. The Rg•••••••••HF complex structure is influenced by this interaction. Hence, these types of van der Waals molecules can be more specifically called Debye molecules

Peter debye

"Not to despair and always be ready to grab the Good which whisks by, without granting the Bad any more room than is absolutely necessary. That is a principle of which I have already made much use. Hopefully, the new year will bring more good than our little faith allows us to see at this moment.

C5H9N Isomers: Pointers to Possible Branched Chain Interstellar Molecules

The astronomical observation of isopropyl cyanide further stresses the link between the chemical composition of the ISM and molecular composition of the meteorites in which there is a dominance of branched chain amino acids as compared to the straight. However, observations of more branched chain molecules in ISM will firmly establish this link. In the light of this, we have considered C5H9N isomeric group in which the next higher member of the alkyl cyanide and other branched chain isomers belong. High-level quantum chemical calculations have been employed in estimating accurate energies of these isomers. From the results, the only isomer of the group that has been astronomically searched, n-butyl cyanide is not the most stable isomer and therefore, which might explain why its search could only yield upper limits of its column density without a successful detection. Rather, the two most stable isomers of the group are the branched chain isomers, tert-butylnitrile and isobutyl cyanide. Based on the rotational constants of these isomers, it is found that the expected intensity of tert-butylnitrile is the maximum among this isomeric group. Thus, this is proposed as the most probable candidate for astronomical observation. A simple LTE (Local thermodynamic equilibrium) modelling has also been carried out to check the possibility of detecting tert-butyl cyanide in the millimetre-wave region.Comment: 16 pages, 1 figur

Study on the Effect of Lime on Biofuel-based (Palm Fatty Acid Distillate) Drilling Fluid

The rising world energy demand has led to exploration for oil and gas in increasingly difficult environments. The exploration has now gone into sensitive regions combining with deviated wells and horizontal well developments under challenging geological formations. Oil-based drilling fluids are widely used in drilling in all parts of the world for highly technical wells and cases. This is because oil-based drilling fluids perform much better than water-based fluids in borehole stabilization and providing lubricity and subsequently faster rates of penetration and performance. However, they are a cause for environmental concern and with the potential of causing bad damage to the environment through mud spills and improper disposal of oil-contaminated drill cuttings and etc. The industry therefore needed an urge to find a fluid that satisfies both the environmental and technical criteria by showing excellent technical performance and it would have to behave like a traditional OBM with all the technical advantages obtaining regulatory approval and being cost-effective. Thus, this project focuses on this concern of developing an environmentally safe biofuel-based drilling fluid with use of Palm fatty acid distillate oil as the base fluid. The drilling fluid produced should satisfy all the needed criteria with required rheological readings and mud performance as compared to conventional diesel-based drilling fluid. Firstly, the main idea behind this project is to study the suitability of palm fatty acid distillate (PFAD) to be used as a continuous fluid in drilling fluids replacing the diesel and mineral oils. Next phase is focused on producing a new drilling fluid system using the PFAD as the base oil. Finally, the effect of different concentrations of lime, which is used as fatty acid activator and alkalinity control agent in drilling fluids is analyzed and studied through the regular mud tests for further optimization

Relationship Between Equilibrium Forms of Lysozyme Crystals and Precipitant Anions

Molecular forces, such as electrostatic, hydrophobic, van der Waals and steric forces, are known to be important in determining protein interactions. These forces are affected by the solution conditions and changing the pH, temperature or the ionic strength of the solution can sharply affect protein interactions. Several investigations of protein crystallization have shown that this process is also strongly dependent on solution conditions. As the ionic strength of the solution is increased, the initially soluble protein may either crystallize or form an amorphous precipitate at high ionic strengths. Studies done on the model protein hen egg white lysozyme have shown that different crystal forms can be easily and reproducibly obtained, depending primarily on the anion used to desolubilize the protein. In this study we employ pyranine to probe the effect of various anions on the water structure. Additionally, lysozyme crystallization was carried out at these conditions and the crystal form was determined by X-ray crystallography. The goal of the study was to understand the physico-chemical basis for the effect of changing the anion concentration on the equilibrium form of lysozyme crystals. It will also verify the hypothesis that the anions, by altering the bulk water structure in the crystallizing solutions, alter the surface energy of the between the crystal faces and the solution and, consequently, the equilibrium form of the crystals

Analysis of Monomer Aggregation and Crystal Growth Rates of Lysozyme

This project was originally conceived to analyze the extensive data of tetragonal lysozyme crystal growth rates collected at NASA/MSFC by Dr. Marc L. Pusey's research group. At that time the lack of analysis of the growth rates was hindering progress in understanding the growth mechanism of tetragonal lysozyme and other protein crystals. After the project was initiated our initial analysis revealed unexpected complexities in the growth rate behavior. This resulted in an expansion in the scope of the project to include a comprehensive investigation of the growth mechanisms of tetragonal lysozyme crystals. A discussion of this research is included as well a list of presentations and publications resulting from the research. This project contributed significantly toward the education of several students and fostered extensive collaborations between investigators