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81.
Vasant R. Choudhary Subhabrata Banerjee Suryakant G. Pataskar 《Journal of Chemical Sciences》2003,115(4):287-298
Combustion of dilute propane (0.9 mol%) over Mn-doped ZrO2 catalysts prepared using different precipitating agents (viz. TMAOH, TEAOH, TPAOH, TBAOH and NH4OH), having different Mn/Zr ratios (0.05—0.67) and calcined at different temperatures (500—800°C), has been thoroughly investigated
at different temperatures (300—500°C) and space velocities (25,000–100,000 cm3 g−1 h−1) for controlling propane emissions from LPG-fuelled vehicles. Mn-doped ZrO2 catalyst shows high propane combustion activity, particularly when its ZrO2 is in the cubic form, when its Mn/Zr ratio is close to 0.2 and when it is prepared using TMAOH as a precipitating agent and
calcined at 500—600°C. Pulse reaction of propane in the absence of free-O2 over Mn-doped ZrO2 (cubic) and Mn-impregnated ZrO2 (monoclinic) catalysts has also been investigated for studying the relative reactivity and mobility of the lattice oxygen
of the two catalysts. Both reactivity and mobility of the lattice oxygen of Mn-doped ZrO2 are found to be much higher than that of Mnimpregnated ZrO2. Propane combustion over Mn-doped ZrO2 catalyst involves a redox mechanism 相似文献
82.
Smrati Gupta Dirk Kuckling Katja Kretschmer Veena Choudhary Hans‐Jürgen Adler 《Journal of polymer science. Part A, Polymer chemistry》2007,45(4):669-679
The aim of this work was the development of a versatile route for the preparation of temperature‐ and pH‐responsive hydrogels with small dimensions. The copolymerization of N,N‐dimethylaminoethyl methacrylate with various amounts (5 and 10 mol %) of dimethylmaleimidoethyl methacrylate in solution with 2,2′‐azobisisobutyronitrile as an initiator is described. The structural and molecular characterization of the copolymers was performed with proton nuclear magnetic resonance, Fourier transform infrared, and ultraviolet spectroscopy, as well as size exclusion chromatography. Differential scanning calorimetry and thermogravimetry were used for the thermal characterization of the copolymers. Micro‐ and nanohydrogels of the copolymers were prepared by photocrosslinking. The gels obtained by photocrosslinking were characterized with a combination of surface plasmon resonance and optical waveguide spectroscopy, dynamic light scattering, and scanning electron microscopy. The hydrogels showed temperature‐ and pH‐responsive behavior. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 669–679, 2007 相似文献
83.
P. G. Oza H. S. Mazumdar A. K. Choudhary K. Gopalan 《Journal of Chemical Sciences》1984,93(2):189-193
A microcomputer system has been designed for semi-automatic operation of a solid source mass spectrometer used for geochronological
studies. It sequentially steps the magnetic field through pre-selected values, reads the digitized ion currents for a given
time and temporarily stores the data which can be transferred to a paper tape or directly to a desk top calculator for further
analysis. The unit is relatively inexpensive, made of readily available components and can be adapted to many laboratory automation
tasks 相似文献
84.
The monoclinic crystal structure of NaH2PO4 at room temperature has been refined from neutron-diffraction measurements on a single-crystal sample and complied with the closely related structure of monoclinic KD2PO4. Attention is paid to the information obtained from these two structures about the geometry of hydrogen (deuterium) bonds ?2.6 A. 相似文献
85.
Choudhary MI Musharraf SG Siddiqui ZA Khan NT Ali RA Ur-Rahman A 《Chemical & pharmaceutical bulletin》2005,53(8):1011-1013
The microbial transformation of an oral contraceptive, mestranol (1) by Cunninghamella elegans yielded two hydroxylated metabolites, 6beta-hydroxymestranol (2) and 6beta,12beta-dihydroxymestranol (3). Metabolite 3 was found to be a new compound. These metabolites were structurally characterized on the basis of spectroscopic techniques. 相似文献
86.
Ahmad I Nawaz SA Afza N Malik A Fatima I Khan SB Ahmad M Choudhary MI 《Chemical & pharmaceutical bulletin》2005,53(8):907-910
Onosmins A (1) and B (2), lipoxygenase inhibitors, have been isolated from Onosma hispida. Their structures were established as 2-[(4-methylbenzyl)amino]benzoic acid (1) and methyl 2-[(4-methylbenzyl)amino]benzoate (2) through spectroscopic studies, including 2D-NMR. The known compounds apigenin (3), 6,4'-dimethoxy-3,5,7-trihydroxyflavone (4), 6,7-dimethoxy-3,5,4'-trihydroxyflavone (5) and apigenin 7-O-beta-D-glucoside (6) are also reported for the first time from this species. Compounds (1) and (2) inhibited lipoxygenase (LOX, EC 1.13.11.12) enzyme in a concentration-dependent fashion with IC50 values of 24.0 and 36.2 microM, respectively. Lineweaver-Burk as well as Dixon plots and their secondary replots indicated that the nature of inhibition was purely a non-competitive type, with K(i) values 22.0 microM and 31.1, respectively. 相似文献
87.
Aziz-Ur-Rehman Malik A Riaz N Ahmad H Nawaz SA Choudhary MI 《Chemical & pharmaceutical bulletin》2005,53(3):263-266
A lignan and two acylphloroglucinols have been isolated from the ethyl acetate soluble fraction of the whole plant of Indigofera hetrantha. Their structures have been assigned on the basis of spectral analysis including 1D and 2D NMR techniques. Compounds 1-3 displayed promising inhibitory potential against enzyme lipoxygenase in concentration-dependent manner. 相似文献
88.
Khan SB Azhar-Ul-Haq Afza N Malik A Khan MT Shah MR Choudhary MI 《Chemical & pharmaceutical bulletin》2005,53(1):86-89
Long-chain esters 1 and 2 have been isolated from the chloroform-soluble fraction of Amberboa ramosa and their structures assigned to be methyl 2beta(2S)-hydroxyl-7(E)-tritriacontenoate (1) and methyl 2beta(2S)-O-beta-D-galactopyranosyl-7(E)-tetratriacontenoate (2). In addition, tricontane (3) and apigenin (4) are also reported for the first time from this species. The structures were assigned on the basis of 1D and 2D NMR techniques. Compounds 1 and 2 showed strong to moderate inhibitory activity against tyrosinase. 相似文献
89.
The ferroelectric lead germanate (Pb5Ge3O11) and its isomorphous compounds are important because of their uses as pyroelectric and electro-optic devices. Comparison
of inter-planar d-spacings of Pb5Ge3−x
Si
x
O11 (x=0, 0.3, 0.7 and 1.00) suggests that there is no change in basic structure of Pb5Ge3−x
Si
x
O11 when Si is substituted for Ge in small quantity (x<1). The dielectric properties of the Si-substituted compounds have been studied as a function of temperature (30 to 200°C).
The ferroelectric-paraelectric phase transition has been observed at 185°C. The Si doping causes (a) Curie point to shift
towards low temperature, (b) peak value of the dielectric constant to decrease and (c) phase transition diffuse. The fast
increase in dielectric constant of pure Pb5Ge3O11 with temperature (beyond transition temperature) may be attributed to the development of space charge polarization in the
system. 相似文献
90.
Michael DG Adamson P Alexopoulos T Allison WW Alner GJ Anderson K Andreopoulos C Andrews M Andrews R Arms KE Armstrong R Arroyo C Auty DJ Avvakumov S Ayres DS Baller B Barish B Barker MA Barnes PD Barr G Barrett WL Beall E Becker BR Belias A Bergfeld T Bernstein RH Bhattacharya D Bishai M Blake A Bocean V Bock B Bock GJ Boehm J Boehnlein DJ Bogert D Border PM Bower C Boyd S Buckley-Geer E Bungau C Byon-Wagner A Cabrera A Chapman JD Chase TR Cherdack D Chernichenko SK Childress S Choudhary BC 《Physical review letters》2006,97(19):191801
This Letter reports results from the MINOS experiment based on its initial exposure to neutrinos from the Fermilab NuMI beam. The rates and energy spectra of charged current nu(mu) interactions are compared in two detectors located along the beam axis at distances of 1 and 735 km. With 1.27 x 10(20) 120 GeV protons incident on the NuMI target, 215 events with energies below 30 GeV are observed at the Far Detector, compared to an expectation of 336+/-14 events. The data are consistent with nu(mu) disappearance via oscillations with |Delta(m)2/32|=2.74 +0.44/-0.26 x10(-3)eV(2) and sin(2)(2theta(23))>0.87 (68% C.L.). 相似文献