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991.
A general stereoselective route to functionalized and substituted tricyclo [5.2.2.0(1,5)]undecenones, tricyclo[6.2.2.0(1,6)]dodecenones, and [3.3.3]- and [4.3.3]propellanes from simple aromatic precursors is reported. The methodology involves generation and cycloaddition of annulated cyclohexa-2,4-dienones with various acrylates followed by manipulation of the resulting tricyclic adducts, leading to functionalized tricyclo[5.2.2.0(1,5)]undecenones and tricyclo[6.2.2.0(1,6)]dodecenones endowed with a beta,gamma-enone chromophore. Photochemical reaction of the tricyclic chromophoric systems followed by reductive cleavage provided an efficient entry into propellanes. 相似文献
992.
993.
Ocaña MF Fraser PD Patel RK Halket JM Bramley PM 《Rapid communications in mass spectrometry : RCM》2007,21(3):319-328
The potential of protein fractionation hyphenated to mass spectrometry (MS) to detect and characterize the transgenic protein present in Roundup Ready soya and maize has been investigated. Genetically modified (GM) soya and maize contain the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene from Agrobacterium tumefaciens CP4, which confers resistance to the herbicide glyphosate. The GM soya and maize proteomes were fractionated by gel filtration, anion-exchange chromatography and sodium dodecyl sulfate/polyacrylamide gel electrophoresis (SDS-PAGE) prior to MS. This facilitated detection of a tryptic peptide map of CP4 EPSPS by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MS and nanoelectrospray ionization quadrupole time-of-flight (nanoESI-QTOF) MS. Subsequently, sequence information from the CP4 EPSPS tryptic peptides was obtained by nanoESI-QTOF MS/MS. The identification was accomplished in 0.9% GM soya seeds, which is the current EU threshold for food-labeling requirements. 相似文献
994.
The catalyzed reporter deposition (CARD) method of signal amplification, also called “tyramide signal amplification”, has
been used in immunoassays not only to increase sensitivity but also to reduce assay time. The current approach to tyramide
amplification in immunoassays involves slow incubation with agitation. In this paper we describe new filtration-based tyramide
amplification and substrate visualization techniques. Compared with the standard method, this new approach greatly enhances
spot intensities in membrane immunoassay and reduces biotinylated tyramide (B-T) and substrate consumption approximately fiftyfold,
without loss of specificity. An improved test device and a cost-effective method for preparation of membranes for Super-CARD
amplification have also been developed. The techniques have been used for rapid detection of aflatoxin B1 (AFB1) in a variety of foodstuffs with a detection limit of 12.5 μg kg−1. The assay procedure involves sequential addition of standards or sample, AFB1–horseradish peroxidase (HRP) conjugate, B-T, avidin–HRP, and substrate solution over anti-AFB1 antibody-spotted zones of the membrane surface. The method saves time, improves reproducibility, eliminates many washing
steps and avoids manipulation of the membranes between the different steps, while maintaining the sensitivity of the standard
method. Average recoveries from different non-infected food samples spiked with AFB1 at concentrations from 25 to 100 mg kg−1 were between 95 and 105%. AFB1 results obtained on different days for Aspergillus parasiticus infection of corn and groundnut samples correlated well with estimates obtained by HPLC.
Figure The principle of filtration-based tyramide filtration technique 相似文献
995.
Raj K. Bansal Neelima Gupta Mukta Baweja Leena Hemrajani Vimal K. Jain 《Heteroatom Chemistry》2001,12(7):602-609
Seven new pyridinium dichlorophosphinomethylides 2 have been obtained from dichlorophosphinylation of the pyridinium methylides generated in situ. 2 give 1,3‐bis(alkoxycarbonyl)‐2‐phosphaindolizines 4 through 1,5‐electrocyclization of the intermediate, bis(pyridinium ylidyl)phosphenium chloride 3 which is generated either from disproportionation of 2 or from the reaction of 2 with pyridinium methylide. Formation of 3 has been confirmed by carrying out a crossed reaction. 3‐Substituted 2 forms 4 regiospecifically. Intramolecular 1,5‐cyclocondensation of 2‐methylpyridinium dichlorophosphinomethylide is preferred over its disproportionation. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:602–609, 2001 相似文献
996.
C. Justin Raj G. Mangalam S. Mary Navis Priya J. Mary Linet C. Vesta S. Dinakaran B. Milton Boaz S. Jerome Das 《Crystal Research and Technology》2007,42(4):344-348
Good optical quality single crystals of zinc hydrogen phosphate (ZnHPO4) having dimensions up to 8×2×2 mm3 have been grown with the aid of sodium meta silicate gel. Single crystal XRD studies confirm that the crystal belongs to the orthorhombic system with space group P212121. The functional groups present in the crystals were confirmed using FTIR technique. Optical absorbance shows very low absorption in the entire visible region. Differential thermal and thermo gravimetric analysis confirmed that the crystal is stable up to 193°C. Photoconductivity study reveals positive photoconductivity in the presence of photo active centers formed by trap energy levels. The NLO activity of the crystal was confirmed by Kurtz powder technique. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
997.
A. Moses Ezhil Raj L. C. Nehru M. Jayachandran C. Sanjeeviraja 《Crystal Research and Technology》2007,42(9):867-875
Transparent dielectric thin films of MgO has been deposited on quartz substrates at different temperatures between 400 and 600°C by a pneumatic spray pyrolysis technique using Mg(CH3COO)2·4H2O as a single molecular precursor. The thermal behavior of the precursor magnesium acetate is described in the results of thermogravimetry analysis (TGA) and differential thermal analysis (DTA). The prepared films are reproducible, adherent to the substrate, pinhole free and uniform. Amongst the different spray process parameters, the substrate temperature effect has been optimized for obtaining single crystalline and transparent MgO thin films. The films crystallize in a cubic structure and X‐ray diffraction measurements have shown that the polycrystalline MgO films prepared at 500°C with (100) and (110) orientations are changed to (100) preferred orientation at 600°C. The MgO phase formation was also confirmed with the recorded Fourier Transform Infrared (FTIR) results. The films deposited at 600°C exhibited highest optical transmittivity (>80%) and the direct band gap energy was found to vary from 4.50 to 5.25 eV with a rise in substrate temperature from 500 to 600°C. The measured sheet resistance and the resistivity of the film prepared at 600°C were respectively 1013Ω/□ and 2.06x107Ω cm. The surface morphology of the prepared MgO thin films was examined by atomic force microscopy. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
998.
V. Mathivanan T. Raghavalu M. Kovendhan S. Gokul Raj G. Ramesh Kumar R. Mohan K. Suriya Kumar 《Crystal Research and Technology》2007,42(9):895-898
L‐histidinium acetate dihydrate {abbreviated as LHAc; [C6H10 N3O2+ C2H3O2‐ 2H2O], a new nonlinear optical (NLO) material has been grown from aqueous solution. The grown crystals were subjected to X‐ray diffraction, Fourier transform infrared (FTIR) and FT‐Raman analyses. Thermal studies have been carried out for its thermal stability. Optical behaviour such as UV‐Vis‐NIR spectrum and second harmonic generation (SHG) were also investigated. Its SHG efficiency was found as deff = 2.2 deff (KDP). (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
999.
S. Krishnan C. Justin Raj R. Robert A. Ramanand S. Jerome Das 《Crystal Research and Technology》2007,42(11):1087-1090
Single crystals of ferroelectric succinic acid were grown from aqueous solution by low temperature solution growth technique. The cell parameters and space group are found using powder X‐ray diffraction analysis. The presence of the functional groups has been estimated qualitatively by FTIR analysis. The UV‐Visible spectrum shows the cut‐off wavelength at 240 nm. The thermal stability of the crystal was studied by TG/DTA. The dielectric constant of the crystal studied as a function of frequency shows the pyroelectric property. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
1000.
In the present study, five different invert trap configurations (rectangular with and without lids on both sides; trapezoidal, trapezoidal with rectangular base and rectangular with trapezoidal base with lids on both sides) were simulated for both two-dimensional (2D) and three-dimensional (3D) flow conditions for three sediment types (sand, styrocell and plastic beads) at six flow rates (0.35, 0.70, 1.05, 1.35, 4.55 and 9.95 L/s) for each trap. Computational fluid dynamics (CFD)-based modeling using FLUENT software with Renormalization Group (RNG) k-e model along with discrete phase model (DPM) were used in the simulations. A hexagonal/tetrahedral and map-type non-uniform grid was chosen to discretize the entire computational domain and a control volume finite difference method was used to solve the governing equations. The flow rates selected in the present study cover the entire range of flow rate expected for dry weather and monsoon. The simulation is capable of differentiating between 2D and 3D modeling of particle trajectories, the effects of flow rate and trap geometry on flow patterns developed in the trap. The sediment retention ratio for 2D is higher than that for 3D modeling for all flow conditions, particle types and model geometry due to inclusion of lateral effects in 3D modeling. The invert trap having rectangular shape with trapezoidal base is found to be the most efficient configuration in both 2D and 3D modeling. 相似文献