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1.
M. M. Abdillahi M. S. Gharami M. A. B. Siddiqui 《Journal of Thermal Analysis and Calorimetry》1994,42(6):1275-1284
Confirmations of the successful synthesis of a particular zeolite demand investigation of the crystals by XRD, SEM, MAS-NMR and chemical analysis. In this work, we have used the DTA exothermic lattice breakdown of theA-zeolite, which gives typical peaks at around 900–1200°C for characterization. The effects ofpH, concentration, time of crystallization and temperature were studied and it was quickly and easily possible to distinguishA-zeolite formation from others originating from the synthesis matrix under different conditions by using DTA/TG analyses. The parameters were optimized for the synthesis of the zeolite and DTA measurements yielded enough information to identify theA-zeolite; this was confirmed by XRD and SEM. 相似文献
2.
3.
BinaS. Siddiqui M.Nadeem Kardar S.Tariq Ali Shazia Khan 《Helvetica chimica acta》2003,86(6):2164-2169
A new obtusafuran derivative, lawsonicin ( 1 ), and a new naphthaquinone, lawsonadeem ( 2 ), along with a known constituent, vomifoliol ( 3 ), were isolated from the aerial parts of Lawsonia alba and characterized by chemical transformation and spectroscopic experiments, including 2D‐NMR techniques. 相似文献
4.
Berhan Teclé Kaniz F. Siddiqui Christopher Ceccarelli John P. Oliver 《Journal of organometallic chemistry》1983,255(1):11-15
The structure of di-trans-β-styrylmercury has been determined by single crystal X-ray methods from counter data. The compound crystallizes in the orthorhombic space group Pbcn with unit cell dimensions a 15.413(6), b 11.161(9), c 7.668(5) Å, V 1319(1) Å3, Dcalc 2.049 g/cm3, and Z = 4. The crystal was solved by conventional heavy atom techniques. The crystal consists of individual molecular units with the mercury atom located on a two fold axis of symmetry. The CHgC fragment is nearly linear with an angle of 178°. The β-styryl groups are oriented so that a dihedral angle of 66.8° is formed between the planes defined by HgC(1)C(2) and HgC(1)′C(2)′ fragments. The HgC bond distance is 2.07(4) Å. 相似文献
5.
Shah BH Siddiqui A Qureshi KA Khan M Rafi S Ujan VA Yakoob MY Yaqub Y Rasheed H Saeed SA 《Experimental & molecular medicine》1999,31(1):42-46
Our previous studies have shown that subthreshold concentrations of two platelet agonists exert synergistic effects on platelet aggregation. Here we studied the mechanism of synergistic interaction of 5-hydroxytryptamine (5-HT) and epinephrine mediated platelet aggregation. We show that 5-HT had no or little effect on aggregation but it did potentiate the aggregation response of epinephrine. The synergistic interaction of 5-HT (1-5 microM) and epinephrine (0.5-2 microM) was inhibited by alpha2-adrenoceptor blocker (yohimbine; IC50= 0.4 microM), calcium channel blockers (verapamil and diltiazem with IC50 of 10 and 48 mM, respectively), PLC inhibitor (U73122; IC50=6 microM) and nitric oxide (NO) donor, SNAP (IC50=1.6 microM)). The data suggest that synergistic effects of platelet agonists are receptor-mediated and occur through multiple signalling pathways including the activation PLC/Ca2+ signalling cascades. 相似文献
6.
Syed A. Ali Mohammed A. Siddiqui and Mohammed A. Ali 《Reaction Kinetics and Catalysis Letters》2005,87(1):199-206
Summary A parametric study of catalytic reforming process in a pilot plant was carried out by varying the pressure, H2/HC ratio, and space velocity. The results show that lower aromatics and higher hydrogen yields can be accomplished by increasing
the space velocity in existing reformers, which will also result in better C5+yield. 相似文献
7.
R. Rajagopal S. A. Siddiqui Thomas Daniel R. J. Lahoti K. V. Srinivasan 《Journal of molecular catalysis. A, Chemical》2004,210(1-2):165-169
Regioselective monobromination of aromatic substrates with N-bromosuccinimide has been achieved in excellent isolated yields (84–98%) using phosphotungstic acid supported on zirconia as a novel heterogeneous catalyst. The catalyst has been characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), surface area and acidity measurements. Remarkably, the new catalyst system described brought about the side-chain bromination of aromatics to afford bromomethyl arenes in excellent yields (86–98%) without the need for a radical initiator. Recovery and recylability of the catalyst have been well established. 相似文献
8.
Afshan Siddiqui Kajal Singh Kanchan Lata Singh Shailendra Kumar Gupta Mohd Safi Ahmad U. N. Tripathi 《应用有机金属化学》2012,26(5):203-211
Mixed ligand complexes of Iron(III) with aspartic acid and 3(2′‐hydroxy phenyl)‐5‐(4′‐substituted phenyl) pyrazolines of type [Fe(C4O4NH6)2(C15H12N2OX)] and [Fe(C4O4NH6)(C15H12N2OX)2], where (C4O4NH6) = aspartate, (C15H12N2OX) = deprotonated 3(2′‐hydroxyphenyl)‐5‐(4′‐substituted phenyl) pyrazolines (X = H, CH3, OCH3, Cl), have been synthesized. These newly synthesized derivatives have been physicochemically characterized by elemental analysis (C, H, N, Cl and Fe), magnetic moment data, thermogravimetric analysis, molar conductance, cyclic voltammetry, spectral analysis (UV–visible, IR, far IR and fast atom bombardment mass spectrometry). Scanning electron microscopy, transmission electron microscopy and X‐ray powder diffraction studies have been carried out for powdered samples, which show nanometric particles of these derivatives. Antibacterial and antifungal potential of free pyrazoline and some iron(III) complexes have been evaluated. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
9.
Malik Abdul Waseem ShireenAnjali Srivastava Arjita SrivastavaRahila I.R. Siddiqui 《Tetrahedron letters》2014
Reusable [bmIm]OH was found to be a highly efficient renewable homogenous catalyst for the rapid and convenient synthesis of benzoxazine-4-one derivatives from o-iodobenzoic-acid and benzonitrile at 75 °C in moderate to good yields. This methodology provides a facile and straightforward path to construct other related heterocycles in an eco-compatible fashion. 相似文献
10.
This paper presents the optimized K-means (OKM) algorithm that can homogenously segment an image into regions of interest with the capability of avoiding the dead centre and trapped centre at local minima phenomena. Despite the fact that the previous improvements of the conventional K-means (KM) algorithm could significantly reduce or avoid the former problem, the latter problem could only be avoided by those algorithms, if an appropriate initial value is assigned to all clusters. In this study the modification on the hard membership concept as employed by the conventional KM algorithm is considered. As the process of a pixel is assigned to its associate cluster, if the pixel has equal distance to two or more adjacent cluster centres, the pixel will be assigned to the cluster with null (e. g., no members) or to the cluster with a lower fitness value. The qualitative and quantitative analyses have been performed to investigate the robustness of the proposed algorithm. It is concluded that from the experimental results, the new approach is effective to avoid dead centre and trapped centre at local minima which leads to producing better and more homogenous segmented images. 相似文献