Dieterici gas as a Unified Model for Dark Matter and Dark Energy

The dominance of dark energy in the universe has necessitated the introduction of a repulsive gravity source to make q0 negative. The models for dark energy range from a simple lambda-term to quintessence, Chaplygin gas, etc. We look at the possibility of how change of behaviour of missing energy density, from DM to DE, may be determined by the change in the equation of state of a background fluid instead of a form of potential. The question of cosmic acceleration can be discussed within the framework of theories which do not necessarily include scalar fields.Comment: 9 pages, 38 equation

The evolution of new generaton 'single-site' Ziegler-Natta polymerization catalysts

Since the discovery of stereospecific polymerization of olefins by K. Ziegler and G. Natta in 1955, tremendous developments have occurred in the area of designing polymerization catalysts. Rapid advances in organometallic chemistry research practised both at academic and industrial laboratories throughout the world have led to the emergence of new generation olefin polymerization catalysts and polyolefin products. The purpose of this article is to highlight some of the major events that have occurred in the area of Ziegler- Natta catalysis and to illustrate the contributions of organometallic chemistry in the exciting story of the evolution of well-defined, 'single-site' metallocene catalysts. The developments in the mechanistic understanding of key steps of polymerization processes such as generation of active species, chain propagation and chain termination emerging from organometallic modeling studies are also highlighted. Also, the recent discovery of late transition metal olefin polymerization catalyst systems and its implications for further research in Ziegler- Natta catalysis is described

Phase Space Constraints on Neutrino Luminosities

While the importance of phase space constraints for gravitational clustering of neutrinos (which are fermions) is well recognized, the explicit use of such constraints to limit neutrino emission from ultra energetic sources has not been stressed. Special and general relativistic phase space constraints are shown to limit neutrino luminosities in compact sources in various situations.Comment: 13 pages, 20 equation

A Critique of Drexler Dark Matter

Drexler dark matter is an alternate approach to dark matter that assumes that highly relativistic protons trapped in the halo of the galaxies could account for the missing mass. We look at various energetics involved in such a scenario such as the energy required to produce such particles and the corresponding lifetimes. Also we look at the energy losses from synchrotron and inverse Compton scattering and their signatures. The Coulomb repulsive instability due to the excess charge around the galaxies is also calculated. The above results lead us to conclude that such a model for DM is unfeasible.Comment: 4 pages, 10 equation

Synthesis and characterization of polyurethane microspheres

A novel particle forming polymerization technique for the preparation of polyurethane microspheres with particle size in the range 0.1-100 micron is described. The method is general, applicable to wide variety of diols and isocyanates and is very simple. The key to successful particle forming polymerization is the use of novel steric stabilizers, such as, a reactive diol containing two primary hydroxyl groups with a long hydrophobic acrylate ester moiety and an amphiphilic block copolymer. The effect of various reactiorr variables on the particle forming polymerization process will be discussed