Linearly polarized, 3.35 W narrow-linewidth, 1150 nm fiber master oscillator power amplifier for frequency doubling to the yellow

A high-power linearly polarized Yb-doped silica fiber master oscillator power amplifier at 1150 nm is reported. It produced 3.35 W cw and 2.33 W of average power in 1 micros pulses at a 100 kHz repetition rate, both with 8 pm linewidth. This is the first report, to the best of our knowledge, of a high-power Yb-doped fiber amplifier at a wavelength longer than 1135 nm. The pulsed output was frequency doubled in a bulk periodically poled near-stoichiometric LiTaO(3) chip to generate 976 mW of average power at 575 nm with an overall system optical-to-optical efficiency of 9.8% with respect to launched pump power.     

Adaptation strategies of the sheathed cyanobacterium Lyngbya majuscula to ultraviolet-B

Lyngbya majuscula is a dominant organism in the east coast of India forming characteristic mat in dried saline soils simultaneously exposed to solar radiation of the tropics. Studies on the growth response, changes in the spectral properties of the methanolic extract and protein profile of this estuarine sheathed cyanobacterium to UV-B revealed existence of effective adaptation mechanism to withstand prolonged UV-B radiation. Carotenoids along with MAAs of the organism was increased with increase in UV irradiation. Increase in thickness of the mucilaginous sheath layer as well as cellular carbohydrate content was observed upon exposure to prolonged UV-B dose. Induction of 21 and 33 kDa low molecular weight proteins, and a 99 kDa protein together with formation of distinct multilayered sheath embedding trichomes with granulated cells were the adaptive features of the organism to cope with UV-B stress. The organism was considerably revived after incubating the irradiated cells in mineral medium under florescent light and in the dark suggesting existence of photoreactivation and dark repair in this cyanobacterium. However more experiments are needed to establish the existence of photoreactivation and dark repair mechanism in the studied cyanobacterium.     

Theoretical study of excited state proton transfer in pyrrole-2-carboxylic acid

Pyrrole 2-carboxylic acid (PCA) shows dual emission (310 nm and 430 nm) in water on photo-excitation, which indicates that more than one species is in the excited state. This paper reports on the quantum chemical analysis of pyrrole 2-carboxylic acid (PCA) in the light of a possible excited state proton transfer. Dipole moment, excited state energy and findings in molecular orbital calculations (HOMO, LUMO) establish that PCA is a likely candidate for transfer of a proton from the pyrrole moiety to the C=O of carboxylic moiety (possible zwitterionic form) in the excited state. Overall, the computed predicted results of intramolecular and intermolecular excited state proton transfer corroborates the experimental results.     

Novel glitazones as PPARγ agonists: molecular design,synthesis, glucose uptake activity and 3D QSAR studies

Background

An alarming requirement for finding newer antidiabetic glitazones as agonists to PPARγ are on its utmost need from past few years as the side effects associated with the available drug therapy is dreadful. In this context, herein, we have made an attempt to develop some novel glitazones as PPARγ agonists, by rational and computer aided drug design approach by implementing the principles of bioisosterism. The designed glitazones are scored for similarity with the developed 3D pharmacophore model and subjected for docking studies against PPARγ proteins. Synthesized by adopting appropriate synthetic methodology and evaluated for in vitro cytotoxicity and glucose uptake assay. Illustrations about the molecular design of glitazones, synthesis, analysis, glucose uptake activity and SAR via 3D QSAR studies are reported.

Results

The computationally designed and synthesized ligands such as 2-(4-((substituted phenylimino)methyl)phenoxy)acetic acid derivatives were analysed by IR, ¹H-NMR, ¹³C-NMR and MS-spectral techniques. The synthesized compounds were evaluated for their in vitro cytotoxicity and glucose uptake assay on 3T3-L1 and L6 cells. Further the activity data was used to develop 3D QSAR model to establish structure activity relationships for glucose uptake activity via CoMSIA studies.

Conclusion

The results of pharmacophore, molecular docking study and in vitro evaluation of synthesized compounds were found to be in good correlation. Specifically, CPD03, 07, 08, 18, 19, 21 and 24 are the candidate glitazones exhibited significant glucose uptake activity. 3D-QSAR model revealed the scope for possible further modifications as part of optimisation to find potent anti-diabetic agents.

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Sugar radicals formed by photoexcitation of guanine cation radical in oligonucleotides

This work presents evidence that photoexcitation of guanine cation radical (G+*) in dGpdG and DNA-oligonucleotides TGT, TGGT, TGGGT, TTGTT, TTGGTT, TTGGTTGGTT, AGA, and AGGGA in frozen glassy aqueous solutions at low temperatures leads to hole transfer to the sugar phosphate backbone and results in high yields of deoxyribose radicals. In this series of oligonucleotides, we find that G+* on photoexcitation at 143 K leads to the formation of predominantly C5'* and C1'* with small amounts of C3'*. Photoconversion yields of G+* to sugar radicals in oligonucleotides decreased as the overall chain length increased. However, for high molecular weight dsDNA (salmon testes) in frozen aqueous solutions, substantial conversion of G+* to C1'* (only) sugar radical is still found (ca. 50%). Within the cohort of sugar radicals formed, we find a relative increase in the formation of C1'* with length of the oligonucleotide, along with decreases in C3'* and C5'*. For dsDNA in frozen solutions, only the formation of C1'* is found via photoexcitation of G+*, without a significant temperature dependence (77-180 K). Long wavelength visible light (>540 nm) is observed to be about as effective as light under 540 nm for photoconversion of G+* to sugar radicals for short oligonucleotides but gradually loses effectiveness with chain length. This wavelength dependence is attributed to base-to-base hole transfer for wavelengths >540 nm. Base-to-sugar hole transfer is suggested to dominate under 540 nm. These results may have implications for a number of investigations of hole transfer through DNA in which DNA holes are subjected to continuous visible illumination.     

A Comparison of the Fluorescence Spectra of Murine and Bovine Central Nervous System and Other Tissues

We describe a comparison of the fluorescence spectra of bovine tissues with murine tissues in order to determine whether spectral features are conserved and whether an appropriate and practical laboratory small animal model system could be identified to be used for investigation of tissue- and age-related fluorescence signal patterns. Recently it has been shown that spectral signatures of lipofuscin have enabled the detection of bovine central nervous system (CNS) tissue in meat products with high sensitivity (Schönenbrücher, H., Adhikary, R., Mukherjee, P., Casey, T.A., Rasmussen, M.A., Maistrovich, F.D., Hamir, A.N., Kehrli, M.J., Richt, J., Petrich, J.W. [2008] J Agric Food Chem 56 , 6220–6226). We report that brain and spinal cord of mice provide fluorescence spectra similar to those of bovine brain and spinal cord. It is concluded that murine CNS tissue is an appropriate model system for bovine CNS tissue for the development of fluorometric CNS detection assays.     

Kadomtsev-Petviashvili (KP) Burgers Equation in Dusty Negative Ion Plasmas: Evolution of Dust-Ion Acoustic Shocks

We study the nonlinear propagation of dust-ion acoustic (DIA) shock waves in an un-magnetized dusty plasma which consists of electrons, both positive and negative ions and negatively charged immobile dust grains. Starting from a set of hydrodynamic equations with the ion thermal pressures and ion kinematic viscosities included, and using a standard reductive perturbation method, the Kadomtsev-Petviashivili-Burgers (K-P-Burgers) equation is derived, which governs the evolution of DIA shocks. A stationary solution of the K-P-Burgers equation is obtained and its properties are analysed with different plasma number densities, ion temperatures and masses. It is shown that a transition from shocks with negative potential to positive one occurs depending on the negative ion concentration in the plasma and the obliqueness of propagation of DIA waves.     

Spin dynamics and spin noise in the presence of randomly varying spin-orbit interaction in a semiconductor quantum wire

Using ensemble Monte Carlo simulation, we have studied hot carrier spin dynamics and spin noise in a multi-subband GaAs quantum wire in the presence of a randomly varying Rashba spin-orbit interaction. The random variation reduces the carrier ensemble's spin dephasing time due to the D'yakonov-Perel' mechanism, but otherwise makes no qualitative difference to the temporal spin relaxation characteristics. However, it makes a qualitative difference to the spatial spin relaxation characteristics which change from monotonic and smooth to non-monotonic and chaotic because of a complex interplay between carriers in different subbands. As far as spin fluctuation and spin noise are concerned, the random variation has no major effect except that the low-frequency noise power spectral density increases slightly when the magnitude of the Rashba spin-orbit interaction field is varied randomly while holding the direction constant.     

String Cloud with Quark Matter in Self-creation Cosmology

We have constructed Bianchi type-III cosmological model with strange quark matter attached to the string cloud in Barber’s (Gen. Relativ. Gravit. 14:117, 1982) second self-creation theory of gravitation which is inflationary. Further it is obtained that the theory leads to Einstein theory at initial epoch and at infinite future.