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91.
V.K. Sinha S.K. Malik D.T. Adroja J. Elbicki S.G. Sankar W.E. Wallace 《Journal of magnetism and magnetic materials》1989,80(2-3):281-284
The DyTiFe11 - xCox (x = 0, 1, 3), HoTiFe11 - xCox (x = 0, 3) and ErTiFe11 compounds, all exhibiting the T hMn12-type structure, were studied for their ac susceptibility in the temperature range 20–300 K. The Dy- and Ho-containing compounds exhibited spin reorientation from axial to cone to planar, or from axial to cone in the temperature range 250-50 K, as expected. In this structure Dy and Ho with negative second-order Stevens' coefficients (J < 0) favor planar rare earth sublattice anisotropy, while Fe and Co sublattices favor uniaxial and planar anisotropies, respectively and would be in competition as a function of temperature. A spin-reorientation type of behavior was also observed in the ErTiFe11 compound near 50 K. This observation appears to imply that, in this compound, the higher-order crystal-field terms are important. The magnetization data revealed that in these systems the rare earth and transition metal sublattices coupled antiparallel, as is normally the case in the heavy rare-earth-transition-metal compounds. 相似文献
92.
By reexamining the analysis of Basu and Biswas, based on the stereographic projection method of Fock and Levy, it is shown
that the general solution of the Wick-Cutkosky model in the instantaneous approximation, hitherto unreported, involves only
one quantum number; this is contrasted with the well-known solution which involves two quantum numbers, but for which the
spectrum is degenerate with respect to one of them. The latter situation is shown to hold under a rather special circumstance. 相似文献
93.
Yihao Tang Malik Hassanaly Venkat Raman Brandon A. Sforzo Jerry Seitzman 《Proceedings of the Combustion Institute》2021,38(2):2589-2596
Fast and reliable high altitude re-ignition is a critical requirement for the development of alternative jet fuels (AJFs). To achieve stable combustion, a spark kernel needs to transit in a partially or fully extinguished flow to develop a flame front. Understanding the relight characteristics of the AJFs is complicated by the chaoticity of the turbulent flow and variations in the spark properties. The focus of this study is the prediction of such characteristics by high-fidelity simulations, with a specific focus on fuel composition effect on the ignition process. For this purpose, a previously developed computational framework is applied, which utilizes high-fidelity LES simulations, a hybrid tabulation approach for modeling forced ignition and detailed quantification of uncertainty resulting from initial and boundary conditions to predict ignition probability. The method is applied to two alternative fuels (named C1 and C5) and Jet-A fuel (named A2) under gaseous conditions. Results show that the mixing of kernel and fuel–air mixture is not affected by the ignition process, but chemistry effects strongly dominate ignition probability. In particular, C1 exhibits much lower ignition probability than the other two fuels, especially at lean operating conditions. More importantly, this behavior is contradictory to ignition delay experiments which predict longer delay times for C5 compared to C1. Comparisons with experiments show that the comprehensive modeling approach captures the ignition trends. Analysis of kernel trajectories in composition space shows that the variations are caused by the relative effects of kernel mixing, response to strain, and ignition properties of the fuel. 相似文献
94.
95.
D. P. Singh V. Malik R. Kumar K. Kumar 《Russian Journal of Coordination Chemistry》2010,36(3):220-225
The condensation reaction of succinyldihydrazide with glyoxal in the presence of divalent metal ions (1: 1: 1) results in
the formation of the complexes of type [M(C6H8N4O2)X2], where M = Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and X = Cl−, NO3−, CH3COO−. The complexes have been characterized with the aid of elemental analyses, conductance measurements and electronic, NMR,
infrared spectral studies. On the basis of these studies, a six-coordinated distorted octahedral geometry in which two nitrogen
and two carbonyl oxygen atoms are suitably placed for coordination toward metal ion, has been proposed for all the complexes.
The complexes were tested for their in vitro antibacterial activity. Some of the complexes showed remarkable antibacterial
activities against some selected bacterial strains. 相似文献
96.
Dubroka A Rössle M Kim KW Malik VK Munzar D Basov DN Schafgans AA Moon SJ Lin CT Haug D Hinkov V Keimer B Wolf T Storey JG Tallon JL Bernhard C 《Physical review letters》2011,106(4):047006
We show that a multilayer analysis of the infrared c-axis response of RBa2Cu3O(7-δ) (R=Y, Gd, Eu) provides important new information about the anomalous normal-state properties of underdoped cuprate high temperature superconductors. In addition to competing correlations which give rise to a pseudogap that depletes the low-energy electronic states below T*?T(c), it enables us to identify the onset of a precursor superconducting state below T(ons)>T(c). We map out the doping phase diagram of T(ons) which reaches a maximum of 180 K at strong underdoping and present magnetic field dependent data which confirm our conclusions. 相似文献
97.
A dynamical non-Abelian 2-form gauge theory (with B∧F term) is endowed with the “scalar” and “vector” gauge symmetry transformations. In our present endeavor, we exploit the latter
gauge symmetry transformations and perform the Becchi–Rouet–Stora–Tyutin (BRST) analysis of the four (3+1)-dimensional (4D)
topologically massive non-Abelian 2-form gauge theory. We demonstrate the existence of some novel features that have, hitherto,
not been observed in the context of BRST approach to 4D (non-)Abelian 1-form as well as Abelian 2-form and 3-form gauge theories.
We comment on the differences between the novel features that emerge in the BRST analysis of the “scalar” and “vector” gauge
symmetries. 相似文献
98.
R. P. Malik 《Physics of Particles and Nuclei Letters》2011,8(3):244-250
We derive absolutely anticommuting Becchi-Rouet-Stora-Tyutin (BRST) and anti-BRST symmetry transformations for the 4D free
Abelian 2-form gauge theory by exploiting the superfield approach to BRST formalism. The antisymmetric tensor gauge field
of the above theory was christened as the “notoph” (i.e. the opposite of “photon”) gauge field by Ogievetsky and Palubarinov
way back in 1966–67. We briefly outline the problems involved in obtaining the absolute anticonimutativity of the (anti-)
BRST transformations and their resolution within the framework of geometrical superfield approach to BRST formalism. One of
the highlights of our results is the emergence of a Curci-Ferrari type of restriction in the context of 4D Abelian 2-form
(notoph) gauge theory which renders the nilpotent (anti-) BRST symmetries of the theory to be absolutely anticommutative in
nature. 相似文献
99.
Mauji Ram Salim Khan Prabhakar Jha Mather A. Khan Usha Kiran Saleem Javed Malik Z. Abdin 《Chromatographia》2008,68(1-2):129-133
A simple, rapid, specific and sensitive thin layer chromatographic (TLC) method has been developed for the quantitative estimation of mevalonic acid (MVA) in leaves of medicinal plants; Artemisia annua, Psorelia corylifolia, Vinca rosea, Withania somnifera and Barleria proinites. The assay procedure involved conversion of MVA to its lactone, mevalonolactone (MVAL). Mevalonic acid was extracted from the leaf tissues of plants. Separation of MVAL was carried out on silica gel 60 F254 TLC plates using benzene:acetone (3:2) as the mobile phase. The densitometric determination of MVAL was performed at 600 nm after derivatization with anisaldehyde reagent in absorption–reflectance mode. The method was validated over the linearity range of 100–500 ng spot?1 and correlation coefficient for the calibration curve was >0.99. The average recovery of MVAL, used as internal standard, was higher than 98%. The lower limit of detection was found to be 50 ng spot?1. 相似文献
100.
Asad Ali Munawar Hussain Imran Malik Alexander Villinger Christine Fischer Peter Langer 《Helvetica chimica acta》2010,93(9):1764-1772
Double Heck cross‐coupling reactions of 2,3‐ and 3,5‐dibromopyridine with various alkenes afforded the corresponding novel di(alkenyl)pyridines. The Heck reaction of 2,5‐dibromopyridine unexpectedly afforded 5,5′‐di(alkenyl)‐2,2′‐bipyridines by palladium‐catalyzed dimerization to give 5,5′‐dibromo‐2,2′‐bipyridine and subsequent twofold Heck reaction. 相似文献