Complex free energy landscapes in biaxial nematics and role of repulsive interactions : A Wang - Landau study

General quadratic Hamiltonian models, describing interaction between crystal molecules (typically with $D_{2h}$ symmetry) take into account couplings between their uniaxial and biaxial tensors. While the attractive contributions arising from interactions between similar tensors of the participating molecules provide for eventual condensation of the respective orders at suitably low temperatures, the role of cross-coupling between unlike tensors is not fully appreciated. Our recent study with an advanced Monte Carlo technique (entropic sampling) showed clearly the increasing relevance of this cross term in determining the phase diagram, contravening in some regions of model parameter space, the predictions of mean field theory and standard Monte Carlo simulation results. In this context, we investigated the phase diagrams and the nature of the phases therein, on two trajectories in the parameter space: one is a line in the interior region of biaxial stability believed to be representative of the real systems, and the second is the extensively investigated parabolic path resulting from the London dispersion approximation. In both the cases, we find the destabilizing effect of increased cross-coupling interactions, which invariably result in the formation of local biaxial organizations inhomogeneously distributed. This manifests as a small, but unmistakable, contribution of biaxial order in the uniaxial phase.The free energy profiles computed in the present study as a function of the two dominant order parameters indicate complex landscapes, reflecting the difficulties in the ready realization of the biaxial phase in the laboratory.Comment: 23 pages, 12 figure

Static and dynamic scheduling in a two station mixed queuing network

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1994.Includes bibliographical references (leaves 77-78).by Kamala P. Murti.M.S

Tip Withering Bug, Anoplocnemis phasiana (Fab.), Halts Grape Shoots: Friend or Foe, Arrival Time Explains

Pruning is a regular practice followed in grapevine, Vitis vinefera L., to keep the vine manageable and productive. However, immediately after pruning, the plants put out a new flush of leaves which attract several leaf-feeding insects, leading to defoliation and crinkling. Incidence of tip withering bug, Anoplocnemis phasiana (Fab.), usually coinciding with the period of halting practice, results in die-back of shoot tip and prevents extension of the shoot, thus halting shoot growth. Intricacies involved in incidence of this coreid bug on grapevine are discussed here

FORMULATION AND EVALUATION OF ORODISPERSIBLE TABLETS OF DONEPEZIL HYDROCHLORIDE

Objective: The present study was aimed to develop the formulation and in vitro evaluation of Orodispersible tablets by wet granulation method using Donepezil HCl as a model drug to enhance patient compliance. Methods: In the wet granulation method, a mixture of microcrystalline cellulose and hydroxypropyl methylcellulose were used along with superdisintegrants, i.e., croscarmellose sodium and crospovidone. The prepared granules were subjected to both pre and post-compression evaluation parameters including; FTIR spectroscopy, micromeritics properties, tablet weight variation, hardness, friability, drug content, disintegration time and in vitro drug release. Results: FTIR studies indicated that there was nointeraction between the drug and the excipients used. The formulation containing high concentration of crospovidone and mixture as the best formulation F2 based on in vitro drug release characteristics of tablet formulation. Conclusion: The results of this work suggested that orodispersible tablets of Donepezil hydrochloride with rapid disintegration time, fast drug release and good hardness can be efficiently and successfully formulated by wet granulation method

Potent antimicrobial activity of Rhizophora mucronata

The antimicrobial activity of n-hexane, chloroform and methanol extracts of leaves and roots of the plant Rhizophora mucronata were studied. Ampicillin and clotrimazole were used as standard antibacterial and antifungal agents respectively. The result of the study revealed that the n-hexane extract and chloroform extract of leaves exhibited strong inhibitory action against Bacillus subtilis, Staphylococcus aureus, Candida albicans, Aspergillus fumigatus and Aspergillus niger and moderate inhibitory action against Pseudomonas aeruginosa and Proteus vulgaris. The rest of the extracts showed good inhibitory activity