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71.
Humayun Ajaz Sajjad Hussain Muhammad Altaf Helen Stoeckli‐Evans Anvarhusein A. Isab Rashid Mahmood Shahnila Altaf Saeed Ahmad 《中国化学》2011,29(2):254-258
Antimony(III) complexes of thioamides [thioamides=thiourea (Tu), N,N′‐dimethylthiourea (Dmtu), tetramethylthiourea (Tmtu), imidazolidine‐2‐thione (Imt) and diazinane‐2‐thione (Diaz)] with the general formulae, Sb(thione)nCl3 (n=1, 2, 2.5, 3) were prepared and characterized by elemental analysis, IR and NMR (1H, 13C) spectroscopic methods. The spectral data of the complexes are consistent with the coordination of the thiones to antimony(III). The crystal structure of one of them, {[Sb(Imt)2Cl2]2(μ2‐Imt)}Cl2 ( 1 ), was determined by X‐ray crystallography, which shows that the complex is dinuclear consisting of two [Sb(Imt)2Cl2] units bridged by an Imt molecule. In 1 , the antimony atom is bonded to two chlorine atoms, two sulfur atoms of coordinated Imt molecules and one sulfur atom of a bridging Imt molecule. The antimony environment can be considered to be distorted octahedral with one Cl? ion weakly bound to antimony. 相似文献
72.
Dengue fever is one of the most dangerous vector‐borne diseases in the world in terms of death and economic cost. Hence, the modeling of dengue fever is of great significance to understand the dynamics of dengue. In this paper, we extend dengue disease transmission models by including transmit vaccinated class, in which a portion of recovered individual loses immunity and moves to the susceptibles with limited immunity and hence a less transmission probability. We obtain the threshold dynamics governed by the basic reproduction number R0; it is shown that the disease‐free equilibrium is locally asymptotically stable if R0 ≤ 1, and the system is uniformly persistence if R0 > 1. We do sensitivity analysis in order to identify the key factors that greatly affect the dengue infection, and the partial rank correlation coefficient (PRCC) values for R0 shows that the bitting rate is the most effective in lowering dengue new infections, and moreover, control of mosquito size plays an essential role in reducing equilibrium level of dengue infection. Hence, the public are highly suggested to control population size of mosquitoes and to use mosquito nets. By formulating the control objective, associated with the low infection and costs, we propose an optimal control question. By the application of optimal control theory, we analyze the existence of optimal control and obtain necessary conditions for optimal controls. Numerical simulations are carried out to show the effectiveness of control strategies; these simulations recommended that control measures such as protection from mosquito bites and mosquito eradication strategies effectively control and eradicate the dengue infections during the whole epidemic. 相似文献
73.
An analysis of quasiparticle correlations with special emphasis on transition matrix elements have been done for a self-consistent
cranking model. It is pointed out that a second order of the boson representation of a transition operator leads to a signature
dependence of transition probabilities between excited one-phonon states in even-even nuclei. Moreover, it brings about the
new contribution to an expectation value of electromagnetic moments in the yrast line states of deformed nuclei. 相似文献
74.
A method is described for the determination of 10–100 nmole of methanal and 20–150 nmole of ethanal and propanal. The method is based on the oxidation of aldehydes to the corresponding acids by mercuric ion which in turn is reduced to elemental mercury, followed by cold-vapour atomic absorption spectrometry. Calibration plots were constructed between the concentration of each aldehyde and absorbance, while the calibration from the conventional cold vapour procedure was used for total aldehydes determination. The method is selective and can be used for aldehyde determination in the presence of ketones, acetals, alcohols, acids, esters, ethers, organic chlorides and epoxides. This simple method is characterised by 98–102% recoveries and standard deviations of 3%. 相似文献
75.
The paramagnetic resonance absorption spectrum of the OD radical in the excited vibrational levels up to v = 5 of the ground , state has been observed at X-band frequencies. The theory of the Zeeman effect of a paramagnetic 2Π state of a light diatomic molecule has been applied to analyze the spectrum. The Λ-doubling frequencies, the molecular g factors, coefficients of the second order Zeeman effect, and the hyperfine interaction constants were determined for each of the vibrational levels. The experimental results agree reasonably well with the values calculated from (a) optical data and (b) ab initio data. The experimental determinations are still much better than theoretical calculations. 相似文献
76.
The temporal characteristics of the output of a single-clad Ho3+, Pr3+-co-doped ZBLAN fibre laser pumped by a Nd:YAG laser at 1064 nm has been found to exhibit a range of cw, self pulsation and
self Q-switching output dynamics, dependent on the excitation and fibre conditions. An interpretation is considered based
on stimulated Brillouin scattering and the effect of the excited state absorption (ESA). For long fibre (∼13 m) and for uni-directional
pumping, the output was a continuous wave (cw), but for bi-directional pumping, a significant decrease in the stability of
the output is observed and the output displayed well developed self pulsations. A train of self Q-switched pulses with mean
pulse duration of 767 ns, a peak pulse power of about 2.8 W and an average power of 183 mW and with more than 80% pulse-to-pulse
stability has been observed when pumped with 4.4 W into each end of the fibre. Self pulsation phenomena are also observed
in unidirectional pumping for shorter fibre lengths of ∼9.2 m at high pump power and for 1.5 m fibre length at all pumps power.
PACS 42.55.Wd; 42.60.Gd; 42.60.Mi 相似文献
77.
Using the Multi-Configuration Dirac-Fock (MCDF) method we calculate with 9 configuration state functions the correlation energy as well as the total energy of the lowestJ=0 ground state of all two-electron systems from H? to Thorium (Z=90). A comparison with experimental data, which are available only in the lowZ region, shows a very good agreement. 相似文献
78.
The condensation process catalysed by 2-amino-3-oxobutyrate CoA ligase (KBL; also known as 2-amino-3-ketobutyrate ligase) involves the loss of the pro-R hydrogen atom of glycine and occurs with the inversion of stereochemistry; a similar scenario is envisaged for the condensation step of other alpha-oxoamine synthases. 相似文献
79.
M. Umar Farooq Mubasher Jamil Muneer A. Rashid 《International Journal of Theoretical Physics》2010,49(10):2334-2347
Holographic dark energy (HDE), presents a dynamical view of dark energy which is consistent with the observational data and
has a solid theoretical background. Its definition follows from the entropy-area relation S(A), where S and A are entropy and area respectively. In the framework of loop quantum gravity, a modified definition of HDE called “entropy-corrected
holographic dark energy” (ECHDE) has been proposed recently to explain dark energy with the help of quantum corrections to
the entropy-area relation. Using this new definition, we establish a correspondence between modified variable Chaplygin gas,
new modified Chaplygin gas and the viscous generalized Chaplygin gas with the entropy corrected holographic dark energy and
reconstruct the corresponding scalar potentials which describe the dynamics of the scalar field. 相似文献
80.
The index of a graded ideal measures the number of linear steps in the graded minimal free resolution of the ideal. In this paper, we study the index of powers and squarefree powers of edge ideals. Our results indicate that the index as a function of the power of an edge ideal I is strictly increasing if I is linearly presented. Examples show that this needs not to be the case for monomial ideals generated in degree greater than two. 相似文献