Drop deformation in stokes flow through converging channels

This work presents an application of a direct BEM formulation for drop deformation and interaction in Stokes flows through converging channels. Parametric studies are conducted to investigate the effect, on drop deformation, of the channel’s convergence ratio, the drop-fluid viscosity ratio, the interfacial tension and the initial relative position of the drops

Evaluation of bacteriological profile and antibiotic susceptibility pattern of patients with otorrhea in a tertiary care teaching hospital

Background: Otitis media is very common disease in developing country and if not treated properly can lead to hearing loss and serious neurological complications. Its bacteriology and antibiotic sensitivity varies in different population. Thus knowledge of the microbiological pattern with antibiotic susceptibility is important to deliver efficacious treatment of this disease. So, purpose of the present study was to determine the microbiological profile and antimicrobial susceptibility pattern of isolates from ear discharge in patients of otitis media.Methods: This study was conducted in Department of Microbiology of our institute for duration of one year. A total of 100 patients’ samples visiting ENT OPD were taken who complaining of ear discharge. Identification of organism was done by using standard biochemical reactions and antibiotic susceptibility testing done by using modified Kirby Bauer method as per CLSI guidelines.Results: Majority of the patients were between 21-30 years of age group (28%). The most common organism isolated was Pseudomonas aeruginosa (25.88%), highly sensitive to aminoglycosides and β-lactam + β-lactamase inhibitor (100%) followed by Staphylococcus aureus (21.17%), highly sensitive to aminoglycosides (100%) and fluoroquinolones (72.22%).Conclusions: Knowledge of the pathogenic agents responsible for otitis media and choice of effective antibiotics according to susceptibility pattern will guide the treatment. It also helps in reducing complications of the disease and decreasing emergence of resistance to antibiotics.

A study of long range order in certain two-dimensional frustrated lattices

We have studied the Heisenberg antiferromagnets on two-dimensional frustrated lattices, triangular and kagome lattices using linear spin-wave theory. A collinear ground state ordering is possible if one of the three bonds in each triangular plaquette of the lattice becomes weaker or frustrated. We study spiral order in the Heisenberg model along with Dzyaloshinskii-Moriya (DM) interaction and in the presence of a magnetic field. The quantum corrections to the ground state energy and sublattice magnetization are calculated analytically in the case of triangular lattice with nearesr-neighbour interaction. The corrections depend on the DM interaction strength and the magnetic field. We find that the DM interaction stabilizes the long-range order, reducing the effect of quantum fluctuations. Similar conclusions are reached for the kagome lattice. We work out the linear spin-wave theory at first with only nearest-neighbour (nn) terms for the kagome lattice. We find that the nn interaction is not sufficient to remove the effects of low energy fluctuations. The flat branch in the excitation spectrum becomes dispersive on addition of furthet neighbour interactions. The ground state energy and the excitation spectrum have been obtained for various cases.Comment: 18 pages, 9 figure

Isolation and characterization of adenosine kinase from Leishmania donovani

Adenosine kinase (ATP:adenosine 5'-phosphotransferase, EC 2.7.1.20) has been purified 3250-fold from Leishmania donovani promastigotes using ion-exchange, gel filtration, and affinity chromatography techniques. Both native and sodium dodecyl sulfate-gel electrophoresis of the enzyme revealed a single polypeptide of around 38,000 molecular weight. Biophysical and biochemical analyses of the enzyme reveal unique characteristics different from those of adenosine kinases from other eukaryotic sources. The isoelectric pH of the enzyme is 8.8. In native acrylamide gels the enzyme moves with an RF of about 0.62. The enzyme displays a maximum activity at pH between 7.5 and 8.5 and is dependent upon an optimum ATP/Mg2+ ratio. ATP at high concentration inhibits the reaction. Adenosine and Mg2+ are not inhibitory. EDTA completely knocks off the activity. Enzyme activity is dependent upon the presence of active thiol group(s) at or near the active center. Under a defined set of conditions the enzyme exhibited an apparent Km for adenosine and ATP of 33 and 50 microM, respectively. Of the nucleoside triphosphates tested ATP and GTP were the most effective phosphate donors. Marginal inhibition of activity was detected with other nucleosides as competitors. However, adenosine analogs, such as 7-deaza-adenosine (tubercidin) and 6-methylmercaptopurine riboside at very low concentrations, were found to be excellent inhibitors and substrates as well. S-Adenosylhomocysteine does not inhibit the reaction even at very high concentration