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191.
Some new complexes of tetravalent molybdenum containing acetylacetone have been synthesized by the reaction of acetylacetone with hydrated molybdenum(IV) oxide. Two series of complexes having varied coordination linkages for acetylacetone have been isolated under appropriate conditions. All the compounds were characterized through their elemental analyses, spectral data, magnetic moment and conductance measurement. 相似文献
192.
Somenath Sarkar Arun Kumar I.C. Goyal Enakshi K. Sharma Ramanand Tewari 《Optics Communications》1985,53(2):91-94
We present an analytical method to evaluate the auxiliary function and spot sizes determining microbending loss in single mode fibers with arbitrary refractive index profiles. Comparison with the exact numerical results shows that the present method gives very accurate results for spot sizes. The method is simple and requires relatively less computational effort. 相似文献
193.
Pratul Bandyopadhyay Brahmananda Bhattacharya Harish Sarkar 《International Journal of Theoretical Physics》1983,22(8):677-689
In quantum neutrinodynamics (photon-neutrino weak coupling) all the renormalization constants vanish and therefore the field equations cannot be expressed in terms of unrenormalized field quantities. This helps us to formulate quantum neutrinodynamics as a convergent quantum field theory. It is also pointed out that from the viewpoint of the unified model of weak and electromagnetic interaction as developed on the basis of the photon-neutrino weak coupling by Bandyopadhyay, quantum electrodynamics also manifests itself as a convergent field theory. 相似文献
194.
195.
Summary [Zn(NH3)4](ReO4)2 and [Cd(NH3)4](ReO4)2 have been prepared from M(ReO4)2 and aqueous ammonia. The tetrapyridine compounds [Zn(py)4(ReO4)2] and [Cd(py)4(ReO4)2] have been obtained by reacting M(NO3)2 with aqueous pyridine followed by the addition of HReO4. Pyrolysis of these complexes gives [Zn(NH3)2(ReO4)2], [Cd(NH3)2(ReO4)2], [Zn(py)2(ReO4)2] and [Cd(py)2(ReO4)2] respectively. The kinetics of the decomposition steps: [ML4(ReO4)2] [ML2(ReO4)2] M(ReO4)2 have been studied from the t.g.a. curves. I.r. and Raman spectral and x-ray powder diffraction studies indicate that all the pyridine complexes and the two diammine complexes contain coordinated perrhenate, while the two tetrammine complexes contain ionic perrhenate. 相似文献
196.
197.
(NEt4)2[WIVO(S2C2(CN)2)2] (1), isolated by reaction of Na2 WO4, Na2S2C2(CN)2 (Na2mnt) in acidified (pH5.5) aqueous medium in the presence of excess of sodium dithionite and NEt4Br, reduces CO2/HCO
3
−
(pH 7.5) to yield HCOO− and (NEt4)2[WVIO2(S2C2(CN)2)2] (2) mimicking tungsten-formate dehydrogenase (W-FDH) activity. (1) reacts with Na2MoO4 in acidic medium to produce [MoIvO(S2C2(CN)2)2]2− implicating the displacement of tungsten by molybdenum from the cofactor complex in W-FDH. 相似文献
198.
We consider the cosmological constraints on unstable particles with masses O(mW). Constraints from the energy density during primordial nucleosynthesis, from subsequent entropy generation, and from perturbations of the microwave background are not as restrictive as bounds from the dissociation of light elements. Most restrictive is the need to avoid over-production of D and 3He through the photo-dissociation of 4He. When applied to gravitinos, this bound imposes an upper limit of O(108) GeV on the reheating temperature after inflation, which could create problems for baryosynthesis in supersymmetric theories. These problems can be avoided if the photino is heavier than the gravitino. 相似文献
199.
Synchronization for a collection of oscillators residing in a finite two dimensional plane is explored. The coupling between any two oscillators in this array is unidirectional, viz., master-slave configuration. Initially the oscillators are distributed randomly in space and their autonomous time-periods follow a Gaussian distribution. The duty cycles of these oscillators, which work under an on-off scenario, are normally distributed as well. It is realized that random hopping of oscillators is a necessary condition for observing global synchronization in this ensemble of oscillators. Global synchronization in the context of the present work is defined as the state in which all the oscillators are rendered identical. Furthermore, there exists an optimal amplitude of random hopping for which the attainment of this global synchronization is the fastest. The present work is deemed to be of relevance to the synchronization phenomena exhibited by pulse coupled oscillators such as a collection of fireflies. 相似文献
200.
Srinivasa Rao Karumuri Joydeep Choudhury Nirmal Kumar Sarkar Ramendu Bhattacharjee 《Pramana》2010,74(1):57-66
Using Lie algebraic techniques and simpler expressions of the matrix elements of Majorana and Casimir operators given by us,
we obtain an effective Hamiltonian operator which conveniently describes stretching vibrations of biomolecules. For a copper
tetramesityl porphyrin molecule, the higher excited vibrational levels are calculated by applying the U(2) algebraic approach. 相似文献