Green biosynthesis of silver nanoparticles and nanomolar detection of p-nitrophenol

Green biosynthesis of nanoparticles and their applications in sensor field is of great interest to the researchers. We report herein a simple green approach for the synthesis of silver nanoparticles (Ag-NPs) using Acacia nilotica Willd twig bark and its application for the detection of 4-nitro phenol (4-NP). The synthesized Ag-NPs were characterized by Transmission electron microscopy, X-ray diffraction and elemental analysis. The size of synthesized Ag-NPs was in the range of 10–50 nm. The Ag-NPs modified electrode shows a high sensitivity and selectivity towards the sensing of 4-NP. The fabricated modified electrode shows a low detection limit of 15 nM on the wider linear response range from 100 nM to 350 μM with the sensitivity of 2.58?±?0.05 μAμM^?1 cm^?2. In addition, the fabricated sensor shows good repeatability and reproducibility.

A convenient synthesis of enantiomerically pure (R)-mexiletine using hydrolytic kinetic resolution method

Enantiopure (R)-mexiletine was prepared in a simple and practical way using hydrolytic kinetic resolution method of terminal epoxide by Jacobsen’s catalyst. High enantiomeric purity (98% ee) was achieved and the method is well amenable to industrial scale-up.     

A facile enantioselective synthesis of enantiomerically pure (R)-phenoxybenzamine hydrochloride using the hydrolytic kinetic resolution method

A practical and highly efficient enantioselective synthesis of (R)-phenoxybenzamine hydrochloride has been described for the first time using Jacobsen’s hydrolytic kinetic resolution of a terminal epoxide as a key step and source of chirality.     

The microwave absorption of emulsions containing aqueous micro- and nanodroplets: a means to optimize microwave heating

The microwave absorption at frequencies between 10 MHz and 4 GHz is measured for aqueous brine droplets dispersed in a dielectric medium (epsilon(')=2.0). By varying the size of the droplets, ion type and ion concentration, it is found that the microwave absorption goes through a maximum which depends on the type of ions and their concentration. The absorption process is attributed to the polarization of the microdroplets through surface charges. Means to optimize microwave heating in emulsions is discussed.     

Immobilized hyperbranched glycoacrylate films as bioactive supports

[Image: see text] We report on the low-pressure plasma immobilization, characterization and application of thin films of hyperbranched glycoacrylates, poly(3-O-acryloyl-alpha,beta-D-glucopyranoside) (AGlc), on PTFE-like fluorocarbon surfaces. This method is an efficient and versatile way to immobilize sugar-carrying branched acrylates as thin films of approximately 5 nm thickness on polymeric substrates while the functional groups and properties of the immobilized molecules are largely retained. The extent of poly(AGlc) degradation during plasma immobilization was investigated using FTIR-ATR spectroscopy and XPS. The thickness and topography of the immobilized films were characterized using spectroscopic ellipsometry and SFM, respectively. Studies of protein adsorption, as well as cell adhesion and proliferation on the poly(AGlc) surfaces, showed that these materials are suitable for the control of biointerfacial phenomena. Fluorescence images of fibronectin adsorbed on to the branched glycoacrylate with a mask.     

A parallel interior point decomposition algorithm for block angular semidefinite programs

We present a two phase interior point decomposition framework for solving semidefinite (SDP) relaxations of sparse maxcut, stable set, and box constrained quadratic programs. In phase 1, we suitably modify the matrix completion scheme of Fukuda et al. (SIAM J. Optim. 11:647–674, 2000) to preprocess an existing SDP into an equivalent SDP in the block-angular form. In phase 2, we solve the resulting block-angular SDP using a regularized interior point decomposition algorithm, in an iterative fashion between a master problem (a quadratic program); and decomposed and distributed subproblems (smaller SDPs) in a parallel and distributed high performance computing environment. We compare our MPI (Message Passing Interface) implementation of the decomposition algorithm on the distributed Henry2 cluster with the OpenMP version of CSDP (Borchers and Young in Comput. Optim. Appl. 37:355–369, 2007) on the IBM Power5 shared memory system at NC State University. Our computational results indicate that the decomposition algorithm (a) solves large SDPs to 2–3 digits of accuracy where CSDP runs out of memory; (b) returns competitive solution times with the OpenMP version of CSDP, and (c) attains a good parallel scalability. Comparing our results with Fujisawa et al. (Optim. Methods Softw. 21:17–39, 2006), we also show that a suitable modification of the matrix completion scheme can be used in the solution of larger SDPs than was previously possible.     

High temperature rate constants for OH+ alkanes

Rate constants for H-atom abstractions by OH radicals from a series of alkanes (propane, n-butane, i-butane and neo-pentane) have been measured at high temperatures with the reflected shock tube technique using multi-pass absorption spectrometric detection of OH radicals at 308 nm. The experiments represent the first direct measurements of these rate constants at T > 1000 K and span a wide T-range, 797-1259 K.The present work utilized 80 optical passes corresponding to a total path length of ∼7 m. As a result of this increased path length, the high [OH] detection sensitivity permitted pseudo-first-order analysis for unambiguously measuring the total rate constants. The experimental rate constants can be represented in Arrhenius form as,

     

Thallium(III) Nitrate Mediated Ring Contraction of 2‐Aryl‐1,2,3,4‐tetrahydro‐4‐quinolones: Stereoselective Synthesis of trans Methyl 2‐Aryl‐2,3‐dihydroindol‐3‐carboxylates

The ring contraction of N‐acetyl‐2‐aryl‐1,2,3,4‐tetrahydro‐4‐quinolones 1a–d with thallium(III) nitrate in trimethyl orthoformate afforded stereoselectively trans methyl N‐acetyl‐2‐aryl‐2,3‐dihydroindol‐3‐carboxylates 5a–d by oxidative rearrangement of aryl ring A.