Greener,solvent free three component Biginelli reaction over different recyclable solid acid catalysts

Solid acids comprising 12-tungstophosphoric acid and 12-tungstosilicic acid anchored on to metal oxide (ZrO₂), zeolites (Hβ and HZSM-5), and mesoporous material (MCM-41) were synthesized, characterized and used as the catalysts. A solvent free green route to carry out the Biginelli cyclocondensation reaction is described over synthesized catalysts. The method provides an efficient and much improved protocol of Biginelli reaction in terms of solvent free conditions, high yields up to 98 %, very short reaction time of 15 min, and simple work-up procedure. Based on the above study a best catalyst among all is proposed and is recycled up to four times without any significant change in % yields of the product. Another important feature of this method is survival of a variety of functional groups under the reaction conditions.     

Solvent-Free Selective Oxidation of Benzyl Alcohol and Benzaldehyde by tert-Butyl Hydroperoxide Using MnO- 4-Exchanged Mg–Al–Hydrotalcite Catalysts

MnO^- ₄ (0.4 mmol/g)-exchanged Mg-Al-hydrotalcite is an active and highly selective catalyst for the oxidation of benzyl alcohol to benzaldehyde by tert-butyl hydroperoxide under reflux in the absence of solvent. It also shows high activity for the oxidation of benzaldehyde to benzoic acid. The higher the Mg/Al ratio, the higher is the catalytic activity (in both the reactions) and basicity of the hydrotalcite catalyst.     

Layer‐by‐layer assembly of halogen‐free polymeric materials on nylon/cotton blend for flame retardant applications

Thin films of environmentally safe, halogen free, anionic sodium phosphate and cationic polysiloxanes were deposited on a Nyco (1:1 nylon/cotton blend) fabric via layer‐by‐layer (LbL) assembly to reduce the inherent flammability of Nyco fabric. In the coating process, we used three different polysiloxane materials containing different amine groups including, 35–45% (trimethylammoniummethylphenythyl)‐methyl siloxane‐55‐65% dimethyl siloxane copolymer chloride salt (QMS‐435), aminoethylaminopropyl silsesquioxane‐methylsilsesquioxane copolymer oligomer (WSA‐7021) and aminopropyl silesquioxane oligomers (WSA‐991), as a positive polyelectrolyte. Thermo‐gravimetric analysis showed that coated fabric has char yield around 40% at 600 °C whereas control fabric was completely consumed. The vertical flame test (VFT) on the LbL‐coated Nyco fabric was passed with after flame time, 2 s, and the char length of 3.81 cm. Volatile and nontoxic degradation products of flame retardant‐coated fabric were analyzed by pyrolysis gas chromatography mass spectroscopy (Py‐GCMS). Surface morphology of coated fabrics and burned fabric residues were studied by scanning electron microscopy. Copyright © 2014 John Wiley & Sons, Ltd.     

Antioxidant effects of broccoli powder extract in goat meat nuggets

The antioxidant potential of broccoli powder extract (BPE) was determined and evaluated in goat meat nuggets at three different levels 1, 1.5 and 2%, compared with control and butylated hydroxyl toluene (100ppm BHT). Total phenolics in 5mg broccoli powder was higher (P<0.05) than 100ppm BHT. Free radical scavenging activity of 2.25mg and 3mg broccoli powder was found similar to 50 and 100ppm BHT. Reducing power of 10mg broccoli powder was comparable to the 100ppm BHT. Incorporation of 1.5 and 2% BPE decreased (P<0.05) the pH value of the products. Total phenolics in product with 2% BPE was similar to BHT nuggets. Chroma value of products with 1.5 and 2% BPE was lower (P<0.05) than control and BHT nuggets. Thiobarbituric acid reactive substances number of BPE nuggets was lower (P<0.05) than control throughout the storage. Thus 2% BPE can be used as natural antioxidant in goat meat nuggets without affecting product acceptability.     

Keggin-type lacunary and transition metal substituted polyoxometalates as heterogeneous catalysts: A recent progress

In this article we discussed synthesis and catalytic applications of heterogeneous catalysts based on lacunary polyoxometalates (LPOMs) and transition metal substituted polyoxometalates (TMSPOMs), however exclusively the focus has been given to the mono LPOMs and mono-TMSPOMs. As the field of supported LPOMs/TMSPOMs is upcoming important field, some aspects about choice of support as well as methods of supporting have also been described. We also include a few of our new research results in order to understand the effect of support and active species as well as choice of organic transformation.     

A review on weight initialization strategies for neural networks

Over the past few years, neural networks have exhibited remarkable results for various applications in machine learning and computer vision. Weight initialization is a significant step employed before training any neural network. The weights of a network are initialized and then adjusted repeatedly while training the network. This is done till the loss converges to a minimum value and an ideal weight matrix is obtained. Thus weight initialization directly drives the convergence of a network. Therefore, the selection of an appropriate weight initialization scheme becomes necessary for end-to-end training. An appropriate technique initializes the weights such that the training of the network is accelerated and the performance is improved. This paper discusses various advances in weight initialization for neural networks. The weight initialization techniques in the literature adopted for feed-forward neural network, convolutional neural network, recurrent neural network and long short term memory network have been discussed in this paper. These techniques are classified as (1) initialization techniques without pre-training, which are further classified into random initialization and data-driven initialization, (2) initialization techniques with pre-training. The different weight initialization and weight optimization techniques which select optimal weights for non-iterative training mechanism have also been discussed. We provide a close overview of different initialization schemes in these categories. This paper concludes with discussions on existing schemes and the future scope for research.

     

PSO Aided Adaptive Complementary Filter for Attitude Estimation

Attitude estimation is one of the core frame- works used for navigating an unmanned aerial vehicle from one place to the other. This paper presents an Euler-based non-linear complementary filter (CF) whose gain parameters are obtained using particle swarm optimization (PSO) technique. It relieves the user from feeding the K _P and K _I parameters manually and adjust these parameters automatically when the error between the attitude measured from accelerometer and the CF increases above a particular threshold. The measurement unit for this research consists of micro-electro-mechanical-systems (MEMS) based low cost tri-axial rate gyros, accelerometers and magnetometers, without resorting to global positioning system (GPS) data. The efficiency of the CF is experimentally investigated with the help of reference attitude and the raw sensor data obtained from commercial inertial measurement unit (IMU). Simulation results based on the test data show that the proposed PSO aided non-linear complementary filter (PNCF) can automatically obtain the required gain parameters and exhibits promising performance for attitude estimation.     

Synthesis and evaluation of luliconazole loaded biodegradable nanogels prepared by pH-responsive Poly (acrylic acid) grafted Sodium Carboxymethyl Cellulose using amine based cross linker for topical targeting: In vitro and Ex vivo assessment

ABSTRACT

Fungal infection in immuno compromised patients causes skin syndromes and problems. At Present, innovative alternatives are required to cure skin disorders and infections. Luliconazole is a novel, broad spectrum, imidazole antifungal agent. The purpose of this study was to develop biodegradable, pH responsive, chemically cross-linked and Poly (acrylic acid) grafted sodium carboxymethyl cellulose nanogels. Nanogels had been synthesized to evaluate its applicability as an effective carrier of luliconazole for topical (skin) targeting. Chemically cross-linked sodium carboxymethyl cellulose-grafted-Poly acrylic acid (NaCMC-g-PAA) was synthesized from acrylic acid and sodium carboxymethyl cellulose using N, N’-methylene bisacrylamide (cross-linker) and potassium persulfate (initiator) using free radical polymerization. Variation of reaction parameters such as pH, cross linker, initiator and temperature has been used to optimize the best one. The developed nanogels reveal significant pH sensitive drug releasing behavior. NaCMC-g-PAA nanogels has been characterized using various physicochemical characterization techniques. Nanogels characteristics were evaluated through the In vitro drug release, Ex vivo permeation study, Nuclear magnetic resonance spectroscopy, Fourier Transform Infrared Spectroscopy, Field Emission Scanning Electron Microscope, Stability Study and antifungal activity. All batches were characterized for particle size analysis and ranged from 78.82 nm to 190 nm. The viscosity of developed nanogels was found to be 5941 cps. It was observed that the developed drug-loaded NaCMC-g-PAA nanogels were more effective in killing the fungus. Consequently, Nanogels incorporated with luliconazole could be a new approach with improved antifungal activity and increased topical delivery for a drug with poor aqueous solubility rather than coarse drug-containing cream.     

Hydrated and anhydrous zinc borate fillers for tuning the flame retardancy of epoxy nanocomposites

In this study, hydrous (Zn₃B₆O₁₂·3.5H₂O) and anhydrous (ZnB₂O₄) forms of zinc borates were synthesized at 150 and 175°C under moderate pressure conditions (85 and 150 psi, respectively). Synthesized zinc borates were controllably incorporated (1, 5, and 10 wt%) in epoxy resin to prepare their nanocomposites. The flame-retardant and mechanical properties of these nanocomposites were determined and compared in terms of their flame spread testing, smoke density, limiting oxygen index, and flexural strength. Superior properties in terms of flame retardancy were observed for epoxy composites containing hydrous filler as compared to anhydrous zinc borates. Although flexural strength was observed to be decreased with increasing filler concentration, the marked drop is lower for composites with hydrous zinc borate as compared to the anhydrous one. The variations in flame-retardant and mechanical properties of composites with both types of fillers are related to their morphological (field emission scanning electron microscopy), X-ray diffraction (XRD) analysis, Fourier Transform Infrared (FTIR), differential scanning calorimetry, and thermogravimetry analysis and explained with condensed phase mechanism.