Chemoenzymatic approaches to SCH 56592, a new azole antifungal

Chemoenzymatic approaches to the synthesis of two key chiral-precursors of a new azole antifungal agent, SCH 56592, are described. In particular, the enzymatic diastereoselective acylation of 2-benzyloxy-3-pentanol (7) was developed to produce (2S;3R)-7 in >97% diastereomeric excess (de) from otherwise unusable mixtures of (2S,3R)/(2S,3S)-7 (40–80% de). The selectivity and reactivity of commercially available Candida rugosa and Mucor miehei lipases are compared for the acylation of 7 and the hydrolysis of the corresponding butyrate 16a. Of the 17 C. rugosa enzyme preparations that were examined for acylation of 7, two purified enzyme preparations showed no reactivity, five enzymes showed high diastereoselectivity with preference for the (2S,3R)-isomer, and seven showed a slight preference for the (2S,3S)-isomer.     

Nanoporous zirconium oxide prepared using the supramolecular templating approach

Hexagonal (Hx-ZrO₂) and lamellar (L-ZrO₂) phases of zirconium oxide have been prepared using the supramolecular templating approach. Long chain primary alkyl amines led to the formation of lamellar phases, while quaternary ammonium surfactants gave hexagonal phases. The materials have been characterized by XRD, TG/DTG, IR, XPS, SEM and EDX techniques. The influence of various synthesis parameters such as (i) the ZrO₂ surfactant ratio, (ii) the surfactant/water ratio, (iii) the nature of surfactant, (iv) the crystallization temperature and (v) the crystallization time have been investigated. The final solid products were found to be thermally unstable regardless of their structure. Removal of the surfactant from the mesopores by solvent extraction without damaging the structure was not possible.     

Emission analysis of CdO–Bi2O3–B2O3 glasses doped with Eu and Tb

This article reports on the emission properties of cadmium bismuth borate (CdBiB) glasses as a function of doping concentrations of Eu³⁺ and Tb³⁺ ions. The functional groups present in the glasses have been identified by analyzing FT-IR spectra. The emission spectra of Eu³⁺ and Tb³⁺:CdBiB glasses have shown reddish green emissions at 616 nm (⁵D₀→⁷F₂) under the excitation at 465 nm and at 547 nm (⁵D₄→⁷F₅) under the excitation at 485 nm, respectively. The Judd–Ofelt (J–O) theory was applied to evaluate the J–O intensity parameters from the absorption and the emission spectra; by using the J–O intensity (Ω_λ) parameters, spontaneous emission transition probability (A), total radiative transition rate (A_T), radiative lifetime (τ_R) and branching ratios (β) of the various emission transitions have been computed for both Eu³⁺ and Tb³⁺:CdBiB glasses. The quenching behavior in the emission intensity with increased concentration of Eu³⁺ and Tb³⁺ was observed, which could be useful for optimizing the compositions toward practical applications.     

Iterative weighted EM and iterative weighted EM′-index for scientific assessment of scholars

Scientometrics - In the field of scientific assessment of scholars, there were several metrics has been given by the scholars. From the list of indices, the h-index is widely accepted for the...     

Statistical-information-based performance criteria for Richardson-Lucy image deblurring

Iterative image deconvolution algorithms generally lack objective criteria for deciding when to terminate iterations, often relying on ad hoc metrics for determining optimal performance. A statistical-information-based analysis of the popular Richardson-Lucy iterative deblurring algorithm is presented after clarification of the detailed nature of noise amplification and resolution recovery as the algorithm iterates. Monitoring the information content of the reconstructed image furnishes an alternative criterion for assessing and stopping such an iterative algorithm. It is straightforward to implement prior knowledge and other conditioning tools in this statistical approach.     

Fabrication,characterization and comparison of DSSC using anatase TiO2 synthesized by various methods

In this study, anatase TiO₂ nanoparticles were synthesized by three techniques, namely, sol–gel, acid-base co-catalyst and room temperature colloidal methods. The synthesized materials were characterized by X-ray diffraction, scanning electron microscopy, pore diameter, pore volume and surface area. The dye-sensitized solar cells were fabricated using the synthesized materials and characterized for incident photon to current conversion efficiency, photocurrent density to photo voltage measurement and electrochemical impedance analysis. Among the studied materials, TiO₂ synthesized by sol–gel method displayed highest photon to current conversion of 76.8% and a maximum solar cell efficiency of 7.85% with J_sc of 14.75 mA/cm², V_oc of 0.76 V and FF of 0.7. This is the first study to report a high power conversion efficiency of DSSC using a sol–gel synthesized titania and its comparison with other two synthesized materials. The high power conversion efficiency of the solar cell using TiO₂ synthesized by sol–gel method is attributed to its characteristic properties such high surface area, larger pore diameter and larger pore volume and highest dye loading capacity.     

Correction to: EM-index: a new measure to evaluate the scientific impact of scientists

Scientometrics - In the original publication, Acknowledgements was published with incomplete information. The complete Acknowledgements is given in this correction.     

Electron Tomography Reveals the Droplet Covered Surface Structure of Nanowires Grown by Aerotaxy

For the purpose of functionalizing III‐V semiconductor nanowires using n‐doping, Sn‐doped GaAs zincblende nanowires are produced, using the growth method of Aerotaxy. The growth conditions used are such that Ga droplets, formed on the nanowire surface, increase in number and concentrations when the Sn‐precursor concentration is increased. Droplet‐covered wires grown with varying Sn concentrations are analyzed by transmission electron microscopy and electron tomography, which together establish the positioning of the droplets to be preferentially on {?111}B facets. These facets have the same polarity as the main wire growth direction, [?1?1?1]B. This means that the generated Ga particles can form nucleation sites for possible nanowire branch growth. The concept of azimuthal mapping is introduced as a useful tool for nanowire surface visualization and evaluation. It is demonstrated here that electron tomography is useful in revealing both the surface and internal morphologies of the nanowires, opening up for applications in the analysis of more structurally complicated systems like radially asymmetrical nanowires. The analysis also gives a further understanding of the limits of the dopants which can be used for Aerotaxy nanowires.     

Efficient mapping of backpropagation algorithm onto a network ofworkstations

In this paper, we present an efficient technique for mapping a backpropagation (BP) learning algorithm for multilayered neural networks onto a network of workstations (NOW's). We adopt a vertical partitioning scheme, where each layer in the neural network is divided into p disjoint partitions, and map each partition onto an independent workstation in a network of p workstations. We present a fully distributed version of the BP algorithm and also its speedup analysis. We compare the performance of our algorithm with a recent work involving the vertical partitioning approach for mapping the BP algorithm onto a distributed memory multiprocessor. Our results on SUN 3/50 NOW's show that we are able to achieve better speedups by using only two communication sets and also by avoiding some redundancy in the weights computation for one training cycle of the algorithm.     

Starch-gum Interactions: Formulations and Functionality Using Amaranth/Corn Starch and CMC

Formulations exploiting starch-gum interactions and using waxy amaranth starch and corn starch (1–5%), and CMC (0–1%) have been worked out. The combinations giving a Brookfield viscosity equivalent to 5% corn starch were found for both the starches. Amaranth starch CMC combinations showed higher viscosities than corn starch-CMC combinations. However, an efficient synergism was observed for corn starch, as seen from Brabender amylograph peak viscosity values. Freeze-thaw stability as well as stability under acidic conditions, retort conditions of 15psig/30min and mechanical shear improved admirably on interaction with CMC. No significant differences between corn and/or amaranth starch were observed when studied for functional properties after interaction with CMC. The only exeption was much better freeze-thaw stability for amaranth starch-CMC combination. This is explained to be due to inherently good freeze-thaw stability of waxy amaranth starch.