Some Studies on Circadian Rhythm in the Culture of Omphalina Quelet sp. (Basidiomycota, Agaricales) A Mycobiont of an Unidentified Basidiolichen

This paper reports the discovery of circadian rhythm in Omphalina Quelet, in pure culture under laboratory conditions. The species was collected as a mycobiont from an unidentified basidiolichen

Exploring hidden dimensions of soil fungal biodiversity: A simple technique to detect soil fungi resistant to antifungal compounds

Soils are known to be ultimate and complex reservoirs of microbial diversity. The complex dimensions of bacterial and fungal diversity in tropical soils and microbial community dynamics are underexplored. Isolation techniques aimed at Actinomycetes generally employ highly selective media, powerful antibiotics and antifungal compounds to suppress undesirable bacteria and fungi. However some soil fungi may show their resistance towards these antifungal compounds. During our work to explore soil actinomycetes diversity, slides coated with Arginine Vitamin agar (AVA) incorporating a cocktail of antibiotics and antifungal compounds such as Nystatin, Cycloheximide, Terbinafin, Griseofulvin, and Fluconazole were exposed to soil environment and were retrieved at intervals of 4, 7, 15 and 28 days for detail microscopic studies of surface colonies. Along with actinomycetes the presence of unidentified aseptate and septate fungi was revealed indicating their resistance to combination and concentration of antifungals. Heat treatment of the soil was found to cause considerable decrease in fungal contamination probably due to elimination of heat labile fungi. Our results have led us to develop a simple procedure to sample the interesting and industrially useful strains of soil fungi resistant to common antifungal compounds. Some fungal strains are reported resistant to certain antifungals with resulting therapeutic failures as use of these antifungals inevitably selects resistant fungi, thereby pressing the urge for continuing and cyclical need of new antifungals (Augustin et al., 2004). This technique could prove useful to detect novel antifungal resistant strains with potential to emerge as novel human pathogens. It has not escaped our notice that the probability of such finding could also help to verify whether these fungi could utilize such antifungal compounds through use of hitherto undiscovered metabolic pathways and novel enzymes leading to identification of genes responsible for antifungal resistance

Digital Image Analysis of Actinomycetes Colonies as a Potential Aid for Rapid Taxonomic Identification

High frequency isolation of actinomycetes poses a challenge for the taxonomists hence simple and rapid identification methods are required. Our work to catalogue biodiversity of actinomycetes of Goa yielded several distinct morphotypes. After their tentative identification, the feasibility to distinguish these using digital image analyses (DIA) was explored. Digital images of wild colony morphotypes were processed using public domain SCION image analysis software. DIA revealed some intricate digital characters. A combination of these with standard morphological and microscopic characters could be potentially useful for preparing a digital identification key of the actinomycetes strains with potential application in rapid taxonomic identification

Two-stroke linear engine

Linear, crankless, internal combustion engines may find application in the generation of electrical power without the need to convert linear to rotary motion. The elimination of the connecting rod and crankshaft can improve the efficiency of the engine significantly and the reduced weight and cost are added advantages. A linear, crankless, internal combustion engine prototype has been developed for electrical power generation in combination with a linear alternator. The operation of this engine is distinct from that of a conventional slider-crank mechanism engine, insofar as the motion of the two horizontally opposed pistons is not externally constrained. A two-stroke engine prototype, with a bore of 36.5 mm and a maximum stroke of 50 mm, operating in a gasoline-fueled spark-ignited mode, was tested successfully under varying externally-applied load and ignition timing conditions. An idealized model analysis also provided an insight into the behavior of the linear engine for different stroke-to-bore (L/b) ratios and under different air-to-find ratios. (Abstract shortened by UMI.)

Improving solubility and supersaturation of poorly soluble drugs using solid dispersions based on natural polymers and mixtures thereof

The poor solubility of existing drug substances and new chemical entities is a problem in modern pharmaceutical development. There are various strategies to overcome the solubility limited bioavailability of poorly soluble drugs. One of the strategies is preparing amorphous solid dispersion (ASDs) using spray drying or hot-melt extrusion (HME). Despite the efforts of several marketed formulations of ASDs, there are fewer research efforts in using natural polymers/excipients for improving solubility and supersaturation maintenance. The objective of this work is to promote the use of natural polymers as a matrix in ASDs a comprehensive study of its application and understanding its influence on the improvement of solubility with supersaturation is essential. To address this, we used different natural polymers in combination with synthetic polymers. The first part of my thesis is dedicated to the pre-screening of the natural polymer inulin in combination in a binary mixture with hydroxy propyl methyl cellulose acetate succinate (HPMC-AS). The film cast in organic solvent showed a single glass transition temperature (Tg) indicating that these two polymers are miscible with each other and subsequently be potentially suitable for spray drying. Other mixtures of shellac (SSB 55) with Affinisol HPMC 15 LV (A15) showed an improved solubility in organic solvent mixtures and the film cast showed a single Tg, in this case, a solvent mixture of acetone/ethanol (50/50) showed improved results in terms of clarity of the casted film. The mixture containing inulin with shellac was insoluble in various organic solvents (acetone, ethanol) and mixtures of acetone/ethanol (50/50) and ethanol/water (95/5). Additionally, inulin/shellac mixtures did not form a one-phasic melt or solid as was showed by two Tgs in DSC measurements, thereby clearly indicating that this combination is not a suitable matrix for manufacturing of ASDs. Lastly, A15 in combination with HPMC-AS was soluble in all tested organic solvents and mixtures thereof and showed a single Tg in DSC measurements making this combination one of the potential lead candidates for the manufacturing of ASDs. Thus, using the pre-screening enabled the selection of natural excipients alone or in combination as a matrix in ASDs development. In continuation of the selection of two lead polymers and their miscibility in each other A15 with shellac was used for the formulation of ASDs. The second part of my work focuses on the use of shellac for preparing binary and ternary ASDs with HPMC, using the model API loratadine (LOR) via spray drying and hot-melt extrusion helped to achieve solubility improvement and supersaturation maintenance. We observed that among various shellac fractions within the ternary ASDs, the 10 % weight fraction optimally increased the solubility 30 folds and maintained the supersaturation for 3 h compared to other binary and ternary formulations. However, lower and higher fractions of shellac decreased the solubility again. This superiority for 10 % weight fraction was due to specific and stronger API matrix interactions detected via ATR-IR, which was further studied in terms of stability. Also, it was found that there exists a correlation between the amount of the dissolved API and the API crystallinity, which dictates the level of supersaturation. While the crystallinity is set by the LOR concentration at the end of the test, the dissolution rate (LOR in dissolution medium) depended on the origin of the crystals i.e., due to recrystallization of previously molecular dispersed LOR or undissolved LOR from HME processing. Thus, the use of shellac is proposed and it will add to the understanding of ternary mixture development with the application of solubility improvement and supersaturation maintenance. The final part of my work highlights the application of shellac for pH-dependent release using HME without the need for coating. The binary solid dispersion (SDD) of API indomethacin (IND) with shellac and IND with Eudragit FS 100 (EFS) and ternary mixtures of IND, SSB 55 together with a new grade of HPMC (A15) were prepared using HME. The SDD were characterized and tested for in-vitro dissolution performance using a pH shift dissolution method from 1.1, 5.5, 6.8, and 7.4. A ternary extrudate of IND, SSB 55, and A15 showed improved protection below pH 5.5 with a complete release of 99.5 % at pH 7.4 compared to IND neat and binary extrudates from IND-A15, IND-SSB 55, and IND-EFS. This increased level of intermolecular interaction was confirmed by AT-IR and studied for stability. It was found that in a ternary mixture containing IND, A15, and SSB 55 an increased hydrogen bonding interaction is present, which resulted in improved dissolution performance compared to binary mixtures with the maintenance of supersaturation. Therefore, ternary SDD proved to be a promising concept for the future development of colon targeting of poorly soluble drugs

Ecological, phenological and biochemical significance of bimodal fruiting of Boletus alutaceus morgan

Boletus alutaceus Morgan an ectomycorrhizal species was extensively studied from an ecologically fragmented microhabitt colonized by its' host plant Ficus benghalensis L. in the Goa University campus, Taleigao, Goa, India. Qualitatively the fruiting cycles were monitored for three years and thereafter detail ecological and morphological investigations were carried out in May and November 2004. A bimodal temporal fruting pattern emerged which may have significant ecological, phenological and biochemical role in EM dynamics

Calibration of flexural design of concrete members reinforced with FRP bars

Fiber Reinforced Polymer (FRP) composites have been increasingly accepted in the construction industry as a promising substitute for steel. Bridge deck deterioration is one of the most common deficiencies in a bridge system. The use of FRP bars as reinforcement for concrete bridge decks provides a potential for increased service life, economic, and environmental benefits. This research presents the development of resistance models for concrete members (beams and slabs) reinforced with FRP bars (FRP-RC), for carrying out reliability analysis. The scope of this model is limited to the flexural behavior only; i.e. the failures are not shear failure and debonding. Probability of Failure,Pf , and Reliability Index, â, of FRP-RC sections are calculated using the developed resistance model. A wide range of design variables is covered in calibrating the flexural design of FRP-RC members, using First Order Reliability Method (FORM). This study results in the development of resistance models for FRP-RC bridge decks and girders which can also be used as resistance models for FRP-RC slabs and beams respectively. Also, the flexural reliability study on FRP-RC slabs and beams yielded parameters that affect the Probability of Failure,Pf , in terms of the Reliability Index, â. These results may be used to enhance the current recommendations for resistance factors

Functional studies of phototaxis in Dictyostelium discoideum mutants

Abstract Dictyostelium discoideum has proven indispensable to elucidate cytoskeletal dynamics. The cytoskeleton plays a key role in almost all cellular processes, including motility, cytokinesis, cell-to-cell and cell-substrate adhesions and intracellular transport. Several actin binding proteins are also involved in these processes, among them are actin crosslinking proteins (for example, filamin and a-actinin). Filamin (also known as ddfilamin or gelation factor or ABP 120) consists of an actin binding domain and six rod repeats of 100 amino acids, its last repeat being responsible for the formation of the homodimer. Both the domains are necessary for the actin crosslinking activity of filamin. Dictyostelium mutants lacking filamin have severe defects in multicellular slug migration towards light, phototaxis, and preferable temperature, thermotaxis. To study the phototaxis defect in filamin- mutants at the molecular level we expressed various domains in the mutant and tested their rescue potential. Expression of C terminally truncated and point mutated (at a putative phosphorylation site) filamin rescued the phototaxis defect partially. Full-length filamin when expressed under the control of the ecmA promoter in the anterior tip of the slug rescues the phototaxis, but not when expressed under the control of the cotB promoter which allows expression in the posterior ¾th of the slug. Phototaxis is a complex phenomenon, which includes more than 55 genes. To identify genes involved in this process we carried out a microarray analysis. Amoung 65 genes we selected in microarray analysis, 40 genes were up regulated and 25 genes were down regulated. From the functions of most of theses genes, we conclude that the phototactic behaviour of slugs is controlled by extracellular cAMP, Ca2+ ions and cell adhesion. To further focus on filamin's function in phototaxis we searched for proteins interacting with filamin by a yeast two hybrid screen and by immunoprecipitation. TipA, GAPA and SapA proteins were pulled down in the immunoprecipitation approach while the FIP, filamin interacting protein, was found earlier in a yeast two hybrid screen. Biochemical studies suggest that FIP is associated with F-actin and may function in vesicle trafficking. Detailed analysis of the mutants of LIM proteins, villidin and filamin for chemotactic migration towards cAMP, led us to conclude that alteration in chemotactic motility of individual cells may not affect the phototactic migration of the slug

Plate Vibration Dispalcement Curve Measurement Using PVDF

Beam and plate dynamics are often measured using accelerometers and in some cases laserbased systems. Natural frequencies, mode shapes, and deflections are then derived from these measurements. The work presented here describes a method to directly measure the deflection curve of a vibrating beam and plate using piezoelectric films. The sensor consists of constant shape segment of PolyVinyliDene Fluoride (PVDF) films bonded to the surface of the structure. We show in here that each segment of the sensor measures the deflection slope at its particular location. The overall lateral displacement curve of the structure (beam/plate) is calculated from these slopes using central difference formulas. In this work, the equations of the sensor are presented along with the results of the numerical verifications. Numerical simulations are executed through MATLAB, whereas Multiphysics simulation is accomplished through ANSYS, and the results of these simulations are compared to the experimental results. The results indicate that the proposed sensors can be used to efficiently and respectively measure the lateral vibration displacements curves of beams and plates with various boundary conditions

Carbon Ignition in Type Ia Supernovae: An Analytic Model

The observable properties of a Type Ia supernova are sensitive to how the nuclear runaway ignites in a Chandrasekhar mass white dwarf - at a single point at its center, off-center, or at multiple points and times. We present a simple analytic model for the runaway based upon a combination of stellar mixing-length theory and recent advances in understanding Rayleigh-Benard convection. The convective flow just prior to runaway is likely to have a strong dipolar component, though higher multipoles may contribute appreciably at the very high Rayleigh number (10$^{25}$) appropriate to the white dwarf core. A likely outcome is multi-point ignition with an exponentially increasing number of ignition points during the few tenths of a second that it takes the runaway to develop. The first sparks ignite approximately 150 - 200 km off center, followed by ignition at smaller radii. Rotation may be important to break the dipole asymmetry of the ignition and give a healthy explosion.Comment: 14 pages, 0 figures, submitted to ApJ, corrected typo in first author's nam