A method for disrupting conidia of Neurospora

Method for disrupting conidi

Catabolite effects on enzymes

Catabolite effects on enzyme

Selecting RNA aptamers for synthetic biology: investigating magnesium dependence and predicting binding affinity.

The ability to generate RNA aptamers for synthetic biology using in vitro selection depends on the informational complexity (IC) needed to specify functional structures that bind target ligands with desired affinities in physiological concentrations of magnesium. We investigate how selection for high-affinity aptamers is constrained by chemical properties of the ligand and the need to bind in low magnesium. We select two sets of RNA aptamers that bind planar ligands with dissociation constants (K(d)s) ranging from 65 nM to 100 microM in physiological buffer conditions. Aptamers selected to bind the non-proteinogenic amino acid, p-amino phenylalanine (pAF), are larger and more informationally complex (i.e., rarer in a pool of random sequences) than aptamers selected to bind a larger fluorescent dye, tetramethylrhodamine (TMR). Interestingly, tighter binding aptamers show less dependence on magnesium than weaker-binding aptamers. Thus, selection for high-affinity binding may automatically lead to structures that are functional in physiological conditions (1-2.5 mM Mg(2+)). We hypothesize that selection for high-affinity binding in physiological conditions is primarily constrained by ligand characteristics such as molecular weight (MW) and the number of rotatable bonds. We suggest that it may be possible to estimate aptamer-ligand affinities and predict whether a particular aptamer-based design goal is achievable before performing the selection

OPTIMIZATION AND CHARACTERIZATION OF ION ACTIVATED OCULAR IN-SITU GEL FORMULATION FOR BACTERIAL CONJUNCTIVITIS

Objective: The present research work aims at describing the formulation, optimization and evaluation of ion activated ocular in-situ gel of gatifloxacin for treatment of bacterial conjunctivitis so as to overcome patient inconvenience, precorneal drug elimination, variation in efficacy, vision blurring and frequent instillation associated with conventional eye drops and ointments. Methods: In-situ gel was prepared using gellan gum as an ion activated phase transition polymer and HPMC K100M as release retardant. Gatifloxacin was characterized by spectrophotometry. Crystalline state of the drug was determined using X Ray Diffraction study. The developed formulation exhibited instantaneous gel formation in simulated lacrimal fluid (pH 7.4), which was further evaluated for its rheology, irritancy parameters, in vitro release, trans-corneal permeation and antimicrobial activity. Results: Gatifloxacin exhibited λmax 286 nm obeying Beer Lambert’s law and pH-dependent solubility at a pH range of 2 to 4. 0.6% gellan gum and 0.4% HPMC K100M were optimized in the formulation which exhibited a viscosity of 55 cps in sol form and 325 cps in gel form with pseudoplastic behavior and prolonged in vitro release. Permeation of formulation was 75.8% in 7 h with log P of drug 0.59. Developed isotonic and non-irritant formulation had a lower apparent permeability coefficient of 8.15 x 10-5 cm/sec as compared to marketed formulation. Conclusion: A Formulation can be viewed as an efficacious medicine by virtue of its higher zone of inhibition, ability to enhance precorneal residence time and consequently ocular bioavailability with lesser frequency of administration attributed to slow and prolonged diffusion of the drug from the polymeric solutions

The Band Gap in Silicon Nanocrystallites

The gap in semiconductor nanocrystallites has been extensively studied both theoretically and experimentally over the last two decades. We have compared a recent ``state-of-the-art'' theoretical calculation with a recent ``state-of-the-art'' experimental observation of the gap in Si nanocrystallite. We find that the two are in substantial disagreement, with the disagreement being more pronounced at smaller sizes. Theoretical calculations appear to over-estimate the gap. Recognizing that the experimental observations are for a distribution of crystallite sizes, we proffer a phenomenological model to reconcile the theory with the experiment. We suggest that similar considerations must dictate comparisons between the theory and experiment vis-a-vis other properties such as radiative rate, decay constant, absorption coefficient, etc.Comment: 5 pages, latex, 2 figures. (Submitted Physical Review B

Submicron gate InP power MISFET's with improved output power density at 18 and 20 GHz

The microwave characteristics are presented at 18 and 20 GHz of submicron gate indium phosphide (InP) metal-insulator-semiconductor field-effect transistors (MISFET's) for high output power density applications. InP power MISFET's were fabricated and the output power density was investigated as a function of drain-source spacing. The best output power density and gain were obtained for drain-source spacing of 3 microns. The output power density is 2.7 times greater than was previously measured for InP MISFET's at 18 and 20 GHz, and the power-added efficiency also increased

Examining consumer acceptance of green innovations using innovation characteristics: A conceptual approach

In the wake of global warming and environmental preservation, all processes and actions are now being directed along the lines of creating a greener environment. Household solar equipments are one such initiative, whereby people around the world are being encouraged to adopt green innovations even within homes. Recent emphasis is particularly along the usage of solar energy for home lighting, heating and cooking. To achieve increased adoption of these green innovations, it is important to understand the behaviours of various factors that may influence consumers in forming favourable intentions towards such innovations. This article aims to develop a theory-based conceptual framework for examining user adoption of household solar innovations. Attributes from Rogers’ Diffusion of Innovations theory, Tornatzky and Klein’s Meta-Analysis, and Moore and Benbasat’s Perceived Characteristics of Innovating theory will be used to design the intended framework for examining the adoption of household solar and other green innovations