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121.
Rasheed AhmadKhera Rasheed Ahmad Ihsan Ullah Obaid‐Ur‐Rahman Abid Olumide Fatunsin Muhammad Sher Alexander Villinger Peter Langer 《Helvetica chimica acta》2010,93(9):1705-1715
2‐Aryl‐2,3‐dihydro‐4H‐pyran‐4‐ones were prepared in one step by cyclocondensation of 1,3‐diketone dianions with aldehydes. The use of HCl (10%) for the aqueous workup proved to be very important to avoid elimination reactions of the 5‐aryl‐5‐hydroxy 1,3‐diones formed as intermediates. The TiCl4‐mediated cyclization of a 2‐aryl‐2,3‐dihydro‐4H‐pyran‐4‐one with 1,3‐silyloxybuta‐1,3‐diene resulted in cleavage of the pyranone moiety and formation of a highly functionalized benzene derivative. 相似文献
122.
Iridium oxide nanoparticles are grown on a glassy carbon electrode by electrodepositing method. The electrochemical behavior and electrocatalytic activity of modified electrode towards reduction of iodate and periodate are studied. The reductions of both ions occur at the unusual positive peak potential of 0.7 V vs. reference electrode. The modified electrode is employed successfully for iodate and periodates detection using cyclic voltammetry, hydrodynamic amperometry and flow injection analysis (FIA). In the performed experiments, flow injection amperometric determination of iodate and periodate yielded calibration curves with the following characteristics: linear dynamic range up to 100 and 80 μM, sensitivity of 140.9 and 150.6 nA μM−1 and detection limits of 5 and 36 nM, respectively. The repeatability of the modified electrode for 21 injections of 1.5 μM of iodate solution is 1.5%. The interference effects of NO2−, NO3−, ClO3−, BrO3−, ClO4−, SO42−, Cu2+, Zn2+, Mn2+, Mg2+, Cd2+, Ca2+, Na+, K+, NH4+ and K+, CH3COO− and glucose were negligible at the concentration ratio of more than 1000. The obtained attractive analytical performance together with high selectivity and simplicity of the proposed method provide an effective and e novel modified electrode to develop an iodate and periodate sensor. Sensitivity, selectivity, the liner concentration range and the detection limit of the developed sensor are all much better than all known similar sensors in the literature for iodate and periodate determination. 相似文献
123.
Aejazur Rahman Saumya S Srivastava Amita Sneh Neesar Ahmed Musti V Krishnasastry 《BMC biochemistry》2010,11(1):35
Background
Mycobacterium tuberculosis is a virulent bacillus causing tuberculosis, a disease responsible for million deaths each year worldwide. In order to understand its mechanism of pathogenesis in humans and to help control tuberculosis, functions of numerous Mycobacterium tuberculosis genes are being characterized. In this study we report the dual functionality of tlyA gene product of Mycobacterium tuberculosis annotated as Rv1694, a 268 amino acid long basic protein. 相似文献124.
Anas M. Abdel Rahman Andreas L. Lopata Robyn E. O'Hehir John J. Robinson Joseph H. Banoub Robert J. Helleur 《Journal of mass spectrometry : JMS》2010,45(4):372-381
The protein tropomyosin (TM) is a known major allergen present in shellfish causing frequent food allergies. TM is also an occupational allergen generated in the working environment of snow crab (Chionoecetes opilio) processing plants. The TM protein was purified from both claw and leg meats of snow crab and analyzed by electrospray ionization and matrix‐assisted laser desorption/ionization (MALDI) using hybrid quadruple time‐of‐flight tandem mass spectrometry (QqToF‐MS). The native polypeptide molecular weight of TM was determined to be 32 733 Da. The protein was further characterized using the ‘bottom‐up’ MS approach. A peptide mass fingerprinting was obtained by two different enzymatic digestions and de novo sequencing of the most abundant peptides performed. Any post‐translational modifications were identified by searching their calculated and predicted molecular weights in precursor ion spectra. The immunological reactivity of snow crab extract was evaluated using specific antibodies and allergenic reactivity assessed with serum of allergic patients. Subsequently, a signature peptide for TM was identified and evaluated in terms of identity and homology using the basic local alignment search tool (BLAST). The identification of a signature peptide for the allergen TM using MALDI‐QqToF‐MS will be critical for the sensitive and specific quantification of this highly allergenic protein in the work place. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
125.
D. M. H. Leung B. M. A. Rahman N. Kejalakshmy K. T. V. Grattan 《Optical and Quantum Electronics》2011,42(8):499-509
The Poynting vector and the full-vectorial H and E-field profiles are considered for use in nanoscale silicon waveguides in this article. This paper reveals that the mode profile
of a circular silicon nanowire is not circular and also has a strong axial field component. From the analysis, the characteristics
of single mode operation and the vector field profiles of both circular and planar silicon nanowires are presented. The modal
birefringence of rectangular silicon nanowires and power density in low-index region of a slot-type waveguide and designs
of a compact polarization rotator are also presented in this work. 相似文献
126.
H. El-Ghandoor Ibraheem Nasser M. A. Abd-El Rahman R. Hassan 《Optics & Laser Technology》2000,32(4):281
A new technique (El-Ghandoor et al., Opt. Laser Technol. 31(7) (1999) 481–488) has been applied to study the shape of transverse interference fringes, instead of multiple beam Fizeau fringes (Marhic, Stein, Appl. Phys. Lett. 35 (1975) 1678–1682), from a GRIN optical fiber. In this technique, a laser light sheet is used to illuminate and pass directly through the optical fiber. Theoretical expressions are derived for the optical path differences of three groups of interference beams. The first one passes through the cladding, the core, and then the cladding once again; the second passes through the cladding only, and the third passes through the surrounding air. Theoretical expressions for the shape of transverse interference fringes formed across isotropic non-absorbing optical fibers are also calculated. 相似文献
127.
128.
Inelastic deformations of stainless steel leaf springs-experiment and nonlinear analysis 总被引:1,自引:0,他引:1
A stainless steel leaf spring is designed and constructed followed by its performance evaluation by experiment and non-linear
analysis so that an insight into the optimum use of material can be made. Cantilever beams of uniform strength, popularly
termed as leaf springs, undergo much larger deflections in comparison to a beam of constant cross-section; that needs inclusions
of geometric non-linearity for rigorous analysis. This study deals with such a cantilever beam, but takes into account the
material non-linearity as well. Experiments were conducted for such a cantilever beam, with highly non-linear stress-strain
curves. In addition to the experiment, a computer code in ‘C’ has been developed using the Runge-Kutta technique for the purpose of simulation. Effective modulus-curvature relations
are obtained from the non-linear stress-strain relations for different sections of the beam and used for the analysis. It
is seen that non-linear stress-strain curve governs the bending of the beam. Importantly, non-linear analysis shows the stresses
are not so high as predicted by the linear theory without end-shortening. Moreover, the tensile and compressive stresses are
different in magnitude and both decrease along the span. Experimental load-deflection curves are found to be initially concave
upward but, non-linear and convex upward at a high load. Comparison of the numerical results with the available experimental
results from another research group and theory shows excellent agreement verifying the soundness of the entire numerical simulation
scheme. 相似文献
129.
V. V. Egorov P. L. Lyaskovskii M. G. Taribo V. A. Nazarov E. M. Rahman’ko L. S. Stanishevskii E. B. Okaev 《Journal of Analytical Chemistry》2010,65(11):1181-1190
Selectivity coefficients of ion-selective electrodes on the basis of liquid anion exchangers, a quaternary phosphonium salt,
and 20 higher quaternary ammonium and other nitrogen-containing salts differing in the length of hydrocarbon radicals, the
nature of the quaternary nitrogen atom, and the presence of polar groups near to the exchange center with respect to 17 mineral,
organic, and metal complex anions are presented. The effect of the nature of the anion-exchanger on the anion selectivity
is discussed. 相似文献
130.