Authors: Raji Heyrovska
Comments: Pages. In Introduction, line 6: "methane [4,5]" should be "ethane "
The structure of benzene and the stacking distances in its dimers have long been of interest for scientists. As the various rigorous approaches over the years to understand these have been complicated, the author presents here a new and simple interpretation through the additivity of atomic covalent radii in bond lengths. Considered here are the distances in pi-pi stacking and T-stacking dimers. The latter appears to be a hydrogen bond between a C atom of one benzene ring and the pi-system of the other.
Authors: H.H. Masjuki, M. Varman, M.Y. Cheah, Y.H. Cheng, M.A. Kalam, A.M. Liaquat, M. Shahabuddin, M. Mofijur
Comments: 13 pages. Paper presented at 2012 International Symposium on Energy Technology and Strategy, Tainan, Taiwan.
Biofuel is one of the prime candidates to take over the role played by fossil fuel as the main
source of energy in the future. Numerous studies have been done on the potential of biofuel to
produce similar power output generated by the current petrol and diesel which are depleting
without any drawbacks. The objective of this particular study is to investigate 4 of the more
established vegetable oil in the energy industry namely jatropha, palm, coconut and canola oil in
terms of storage stability of biofuel at room temperature and 80ºC. The biofuels were tested in
terms of density, kinematic viscosity, Total Acid Number (TAN), flash point and oxidation stability every 2 weeks for 10-12 weeks or 3 months at 2 different temperatures to obtain a conspicuous result. At the end of the experiment and test, it is found that palm oil is the biofuel with the best storage stability. The next biofuel that followed is jatropha oil, canola oil and finally coconut oil. Although palm oil showed poor kinematic viscosity, however it has good
stability in terms of density, Total Acid Number (TAN) and also relatively stable oxidation and
flash point in comparison with the 4 samples tested. The experiment result and data also showed
that effect of continuous heating at 80ºC promotes oxidation process, higher Total Acid Number (TAN), lower flash point as well as increase in density and kinematic viscosity.
Next, experimental investigations were carried out to evaluate the storage stabilities of various
biodiesel fuels. The biodiesel fuels were palm methyl ester (PME), jatropha methyl ester (JME),
coconut methyl ester (COME), 20% blends of PME with diesel fuel and 20% blends of JME with diesel fuel. The ordinary diesel fuel was used for comparison purposes. The biodiesel were
tested in terms of density, kinematic viscosity, Total Acid Number (TAN), flash point and oxidation stability every week for 3 months. The results show that almost all fuel samples met
the standard specifications regarding oxidation stability. The trends for density, viscosity and
TAN increased due to oxidation. For the flash point, the trend also decreased, but the rate was
very low. In overall consideration, among the biodiesel, COME was found to be better with
respect to storage stabilities. The results of this investigation will be used for sustainable
development of biodiesel fuel from various feedstocks
Authors: Raji Heyrovska
Comments: 5 pages, 3 Figures
Diborane is an unusual molecule with two boron atoms bonded to four terminal hydrogen atoms and two bridging hydrogen atoms. This has puzzled many scientists and gave rise to many theories, with no final definitive explanation. This article brings a simple explanation of the bond lengths and angles in diborane, based on the additivity of atomic and Golden ratio based ionic radii, which was found applicable for many other bonds in small as well as small molecules.
Authors: Sosale Chandrasekhar
Comments: 13 Pages.
The Hansch equation is a key mathematical relationship and a conceptual guiding principle (QSAR) in the practice of modern medicinal chemistry. Recent years have apparently witnessed a debate on the utility of QSAR, hence it seems opportune to explore its fundamental origins. The Hansch equation leads to a parabolic relationship between drug activity and hydrophobicity. Currently, this is explained on the basis of more efficient drug-receptor interaction at low to moderate hydrophobicity, and decreasing aqueous solubility of the drug at moderate to high hydrophobicity. Herein is presented an alternative kinetic model, essentially based on the rate of the drug-receptor interaction; thus, binding is rate determining up to moderate levels of hydrophobicity, beyond which drug release is rate determining. The overall model is based on the idea that the release of the drug occurs concurrently with a physiological response, although alternative variants are also discussed. Overall, it is argued that QSAR essentially indicates the primacy of electronic over steric effects. This has fundamental implications for the classical theory of drug-receptor binding, which may need to be appropriately reassessed. Thus, the observed structure-activity relationships possibly apply to the kinetics of drug-receptor binding, likely involving substrate-induced conformational changes within the receptor, prior to the binding event. Recent developments in receptor-based drug design methodology apparently support these views.