Biguanidine‐functionalized chitosan to immobilize palladium nanoparticles as a novel,efficient and recyclable heterogeneous nanocatalyst for Suzuki–Miyaura coupling reactions

Biguanidine‐functionalized chitosan was synthesized and combined with palladium nanoparticles to yield a recyclable, environmentally benign, heterogeneous catalytic system for the Suzuki–Miyaura C–C coupling reaction. The catalyst was characterized using various techniques. The catalyst was used in Suzuki cross‐coupling reactions of various aryl halides, including less reactive chlorobenzenes, with phenylboronic acid to give biaryls without any additive or ligand. A reusability test demonstrated that the catalyst was highly efficient even after six runs. Solid‐phase poisoning and leaching tests indicated that the catalyst has a heterogeneous nature. Copyright © 2016 John Wiley & Sons, Ltd.     

Laser Induced Surface Morphology of Molybdenum Correlated with Breakdown Spectroscopy

Surface modifications of laser irradiated molybdenum have been correlated with plasma parameters. Nd:YAG laser (1064 nm, 10 ns) was employed at various laser irradiances ranging from 6 to 50 GW/cm² under argon environment. The ablation efficiency has been investigated by measuring the crater depth using surface profilometry analysis. Scanning electron microscope (SEM) analysis reveals the formation of coarse grains along with cracked boundaries, cavities and cones at the central ablated areas. Whereas, uplifted re-solidified material, cavities, ridges, droplets and cones were observed at boundary regions. Laser Induced Breakdown Spectroscopy (LIBS) analysis has been performed to evaluate electron temperature and number density of molybdenum plasma. Electron temperature and electron density varies from 6670 to 9305 K and 0.62 × 10¹⁸ to 0.72 × 10¹⁸ cm^?3 respectively. Both the parameters showed similar trend in variation with laser irradiance i.e. an initial increase from 13 to 19 GW/cm² followed by a decrease from 19 to 25 GW/cm² and then a saturation from 25 to 50 GW/cm². The initial increasing trend is attributed to the enhanced excited vapor content of the ablated material, confinement effects of the surrounding argon and absorption of laser energy into the molybdenum vapor plasma during the trailing part of laser pulse leading to ignition of laser supported combustion (LSW) waves. The decreasing trend is attributed to the shielding effect and saturation is explainable on the basis of the formation of a self-regulating regime. Surface modifications of laser irradiated molybdenum were correlated with the plasma parameters.     

Green synthesis and chemical characterization of gold nanoparticle synthesized using Camellia sinensis leaf aqueous extract for the treatment of acute myeloid leukemia in comparison to daunorubicin in a leukemic mouse model

According to chemotherapeutic properties of medicinal plants, pharmacologists have always tried to synthesize and formulate the new chemotherapeutic supplements or drugs of metallic nanoparticles using plants. In this study, Camellia sinensis leaf aqueous extract-based gold nanoparticles (AuNPs) are reported for the first time to exert a dietary therapeutic potential compared to Daunorubicin in an animal model of acute myeloid leukemia. The synthesized AuNPs were characterized using different techniques including UV-Vis., FT-IR spectroscopy, TEM, EDS, FE-SEM, and XRD. DPPH free radical scavenging test was done to evaluate the antioxidant potentials of HAuCl₄, C. sinensis, AuNPs, and daunorubicin. For the analyzing of cytotoxicity effects of HAuCl₄, C. sinensis, AuNPs, and daunorubicin, MTT assay was used on HUVEC, Human HL-60/vcr, 32D-FLT3-ITD, and Murine C1498 cell lines. In vivo design, induction of acute myeloid leukemia was done by 7,12-Dimethylbenz[a]anthracene (DMBA) in 75 mice. Then, the animals were randomly divided into six subgroups, including control, untreated, HAuCl₄, C. sinensis, AuNPs, and daunorubicin. FTIR findings suggested antioxidant compounds in the nanoparticles were the sources of reducing power, reducing gold ions to AuNPs. SEM and TEM images exhibited a uniform spherical morphology and diameters of ~20-30 nm for the nanoparticles. DPPH test revealed similar antioxidant potentials for daunorubicin and AuNPs. These nanoparticles similar to daunorubicin had low cell viability dose-dependently against Human HL-60/vcr, 32D-FLT3-ITD, and Murine C1498 cell lines without any cytotoxicity on HUVEC cell line. AuNPs similar to daunorubicin, significantly (p≤0.05) increased the anti-inflammatory cytokines and the lymphocyte, platelet, and RBC parameters and decreased the weight and volume of liver and spleen, the pro-inflammatory cytokines, and the total WBC, blast, neutrophil, monocyte, eosinophil, and basophil counts, as compared to the untreated mice. According to the above results, it appears that AuNPs can be used as a chemotherapeutic drug for the treatment of acute myeloid leukemia in the clinical trial.     

Microextraction of Rosmarinic Acid Using CMK-3 Nanoporous Carbon in a Packed Syringe

CMK-3 nanoporous carbon was prepared and used as an efficient sorbent for microextraction in packed syringe of rosmarinic acid in Rosmarinus officinalis L. (rosemary). In the proposed method, only 2 mg of the nanoporous material, inserted between a syringe’s barrel and needle, was sufficient for the extraction with minimum consumption of organic solvents. Sample preparation was performed on the packed bed using a laboratory-made programmable apparatus. The apparatus was designed and used for automation of the conditioning, sampling, washing and elution steps of the method, and increasing the reproducibility of the experiments. For optimization of the experimental parameters, a central composite design method was used. Under the optimized conditions (i.e., number of adsorption cycles 14 times, number of elution cycles ten times and volume of elution 100 μL), an extraction recovery of 90 (±4.5) % was obtained for rosmarinic acid. The same packing bed could be used for at least 80 extractions without significant changes in its properties. The efficiency of the nanoporous sorbent was found to be superior to that of activated carbon, by a factor of about 17. The proposed method was successfully applied to the extraction of three rosemary samples before analysis by HPLC.

     

Optimal Non-Linear Models for Sparsity and Sampling

Given a set of vectors (the data) in a Hilbert space ?, we prove the existence of an optimal collection of subspaces minimizing the sum of the square of the distances between each vector and its closest subspace in the collection. This collection of subspaces gives the best sparse representation for the given data, in a sense defined in the paper, and provides an optimal model for sampling in union of subspaces. The results are proved in a general setting and then applied to the case of low dimensional subspaces of ? ^N and to infinite dimensional shift-invariant spaces in L ²(? ^d ). We also present an iterative search algorithm for finding the solution subspaces. These results are tightly connected to the new emergent theories of compressed sensing and dictionary design, signal models for signals with finite rate of innovation, and the subspace segmentation problem.     

Slanted matrices, Banach frames, and sampling

In this paper we present a rare combination of abstract results on the spectral properties of slanted matrices and some of their very specific applications to frame theory and sampling problems. We show that for a large class of slanted matrices boundedness below of the corresponding operator in ?p for some p implies boundedness below in ?p for all p. We use the established result to enrich our understanding of Banach frames and obtain new results for irregular sampling problems. We also present a version of a non-commutative Wiener's lemma for slanted matrices.     

Evaluation of toxic metals in the industrial effluents and their segregation through peanut husk fence for pollution abatement

The industrial pollution is exponentially growing in the developing countries due to the discharge of untreated effluents from the industries in the open atmosphere. This may cause severe health hazards in the general public. To reduce this effect, it is essential to remove the toxic and heavy metals from the effluents before their disposal into the biosphere. In this context, samples of the effluents were collected from the textile/yarn, ceramics and pulp/paper industries and the concentrations of the toxic metal ions were determined using neutron activation analysis (NAA) technique. The observed concentration values of the As, Cr and Fe ions, in the unprocessed industrial effluents, were 4.91 ± 0.8, 9.67 ± 0.7 and 9.71 ± 0.8 mg/L, respectively which was well above the standard recommended limits (i.e. 1.0, 1.0 and 2.0 mg/L, respectively). In order to remove the toxic metal ions from the effluents, the samples were treated with pea nut husk fence. After this treatment, 91.5% arsenic, 81.9% chromium and 66.5% iron metal ions were successfully removed from the effluents. Then the treated effluents contained concerned toxic metal ions concentrations within the permissible limits as recommended by the national environmental quality standards (NEQS).     

An exclusive kinetic model for the methylcyclohexane dehydrogenation over alumina-supported Pt catalysts

The experimental data of six different types of Pt-containing alumina catalysts are used to study the detailed and rigorous kinetics of the methylcyclohexane dehydrogenation reaction. A large number of kinetic rate equations were formulated using the power law kinetics and the Langmuir-Hinshelwood-Hougen-Watson (LHHW) kinetics, which were tested against the experimental data. For each catalyst, the elementary reaction step “the loss of first molecular hydrogen” in the LHHW single-site surface reaction mechanism was observed to be the rate-determining step. The form of the kinetic rate model developed in the study is believed to be applicable to any Pt-loaded alumina catalyst.     

Synthesis of tetracyclic pyrido-fused dibenzodiazepines via a catalyst-free cascade reaction

Molecular Diversity - An efficient, eco-friendly protocol has been described for the chemoselective synthesis of tetracyclic pyrido-fused dibenzodiazepines derivatives via catalyst-free,...