Facile and Sensitive Spectrophotometric Determination of Propoxur in Formulations and Environmental Samples

A facile, rapid, and sensitive spectrophotometric method for the determination of propoxur in insecticidal formulations, fortified water, vegetables, agricultural wastewater, and agricultural soil samples has been elaborated. The proposed method is based on the hydrolysis of propoxur under basic conditions, followed by instantaneous azo coupling of the resulting 2‐isopropoxyphenol with the anilines 2a – c . This yielded the orange‐red chromophore 3a (λ_max=at 470 nm), the pale‐red coupling product 3b (490 nm), or the red derivative 3c (478 nm), which are stable for 46 h, 38 h, and 24 h, respectively, and could be readily analyzed spectrophotometrically.     

Regioselective cleavage of the bis-benzylidene acetal of d-mannitol under oxidative and reductive conditions: a new approach to C2-symmetric chiral ligands

A highly regioselective oxidative cleavage of 1,3:4,6-di-O-benzylidene-d-mannitol was carried out using NBS and the resultant product was readily converted to the C₂-symmetric chiral ligand, (R,R)-3,4-dihydroxy-1,5-hexadiene. On the other hand, reductive cleavage of 1,3:4,6-di-O-benzylidene-d-mannitol was achieved in a highly regioselective manner using BF₃·OEt₂ and Et₃SiH to give a highly functionalized benzyl ether, which was converted to a synthetically useful C₂-symmetric bis-amino alcohol derivative.     

Determination of rhodium in water samples using cloud point extraction (CPE) coupled with flame atomic absorption spectrometry (FAAS)

Cloud point extraction was applied as a method for preconcentration of rhodium after formation of a complex with 2-propylpiperidine-1-carbodithioate (2-PPC), and later determined by flame atomic absorption spectrometry using TritonX-114 as surfactant. Rhodium was complexed with 2-PPC in an aqueous phase and kept for 15 min in a thermostatted bath at 40 °C. Separation of the two phases was accomplished by centrifugation for 15 min at 4000 rpm. The chemical variables affecting the cloud point extraction were optimized and successfully applied to rhodium determination in various water samples. Under optimized conditions, the preconcentration system (100 mL sample) permitted an enhancement factor of 50. The detection limits obtained under optimal conditions was 0.052 ng mL⁻¹. The extraction efficiency was investigated at different rhodium concentrations (7.0–42.0 μg mL⁻¹), and good recoveries (96.42–99.14%) were obtained using this method. It has been applied to the determination of rhodium in water and was compared with reported methods in terms of Student’s ‘t’-test and variance ratio ‘f’-test.     

Shotgun proteomics‐based clinical testing for diagnosis and classification of amyloidosis

Shotgun proteomics technology has matured in the research laboratories and is poised to enter clinical laboratories. However, the road to this transition is sprinkled with major technical unknowns such as long‐term stability of the platform, reproducibility of the technology and clinical utility over traditional antibody‐based platforms. Further, regulatory bodies that oversee the clinical laboratory operations are unfamiliar with this new technology. As a result, diagnostic laboratories have avoided using shotgun proteomics for routine diagnostics. In this perspectives article, we describe the clinical implementation of a shotgun proteomics assay for amyloid subtyping, with a special emphasis on standardizing the platform for better quality control and earning clinical acceptance. This assay is the first shotgun proteomics assay to receive regulatory approval for patient diagnosis. The blueprint of this assay can be utilized to develop novel proteomics assays for detecting numerous other disease pathologies. Copyright © 2013 John Wiley & Sons, Ltd.     

Scalable bottom‐up assembly of suspended carbon nanotube and graphene devices by dielectrophoresis

Bottom‐up assembly by dielectrophoresis (DEP) has emerged in recent years as a viable alternative to conventional top–down fabrication of electronic devices from nanomaterials, particularly carbon nanotubes and graphene. Here, we demonstrate how this technique can be extended to fabricate devices containing carbon nanotubes and graphene suspended between two electrodes over a back‐gate electrode. The suspended device geometry is critical for the development of nano‐electromechanical devices and to extract maximum performance out of electronic and optoelectronic devices. This technique allows for parallel assembly of devices over large scale. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Optimization of the Production of Thermostable endo-β-1,4 Mannanases from a Newly Isolated <Emphasis Type="Italic">Aspergillus niger gr</Emphasis> and <Emphasis Type="Italic">Aspergillus flavus gr</Emphasis>

The aim of this work was to establish optimal conditions for the maximum production of endo-β-1,4 mannanases using cheaper sources. Eight thermotolerant fungal strains were isolated from garden soil and compost samples collected in and around the Gulbarga University campus, India. Two strains were selected based on their ability to produce considerable endo-β-1,4 mannanases activity while growing in liquid medium at 37 °C with locust bean gum (LBG) as the only carbon source. They were identified as Aspergillus niger gr and Aspergillus flavus gr. The experiment to evaluate the effect of different carbon sources, nitrogen sources, temperatures and initial pH of the medium on maximal enzyme production was studied. Enzyme productivity was influenced by the type of polysaccharide used as the carbon source. Copra meal defatted with n-hexane showed to be a better substrate than LBG and guar gum for endo-β-1,4 mannanases production by A. niger gr (40.011 U/ml), but for A. flavus gr (33.532 U/ml), the difference was not significant. Endo-β-1,4 mannanases produced from A. niger gr and A. flavus gr have high optimum temperature (65 and 60 °C) and good thermostability in the absence of any stabilizers (maintaining 50% of residual activity for 8 and 6 h, respectively, at 60 °C) and are stable over in a wide pH range. These new strains offer an attractive alternative source of enzymes for the food and feed processing industries.     

HOW REYE'S CONFIGURATION HELPS IN PROVING THE BELL–KOCHEN–SPECKER THEOREM: A CURIOUS GEOMETRICAL TALE

It is shown that the 24 quantum states or rays used by Peres (J. Phys. A 24, 174-8 (1991)) to give a proof of the Bell–Kochen–Specker (BKS) theorem have a close connection with Reye's configuration, a system of twelve points and sixteen lines known to projective geometers for over a century. The interest of this observation stems from the fact that it provides a ready explanation for many of the regularities exhibited by the Peres rays and also permits a systematic construction of all possible non-coloring proofs of the BKS theorem based on these rays. An elementary exposition of the connection between the Peres rays and Reye's configuration is given, following which its applications to the BKS theorem are discussed.     

A stable high-order Spectral Difference method for hyperbolic conservation laws on triangular elements

Numerical schemes using piecewise polynomial approximation are very popular for high order discretization of conservation laws. While the most widely used numerical scheme under this paradigm appears to be the Discontinuous Galerkin method, the Spectral Difference scheme has often been found attractive as well, because of its simplicity of formulation and implementation. However, recently it has been shown that the scheme is not linearly stable on triangles. In this paper we present an alternate formulation of the scheme, featuring a new flux interpolation technique using Raviart–Thomas spaces, which proves stable under a similar linear analysis in which the standard scheme failed. We demonstrate viability of the concept by showing linear stability both in the semi-discrete sense and for time stepping schemes of the SSP Runge–Kutta type. Furthermore, we present convergence studies, as well as case studies in compressible flow simulation using the Euler equations.