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Search Results: 1 - 10 of 19880 matches for " Type-I Dyotropic Reactions "
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An Adjusted Model for Simple 1,2-Dyotropic Reactions. Ab Initio MO and VB Considerations  [PDF]
Henk M. Buck
Open Journal of Physical Chemistry (OJPC) , 2013, DOI: 10.4236/ojpc.2013.33015
Abstract:

With an adjusted model, we reconsider simple 1,2-dyotropic reactions with the introduction of a concept based on the intramolecular dynamics of a tetrahedron (van ’t Hoff modeling). In fact the dyotropic reactions are strongly related to conversions originated from neighbouring group participation or anchimeric assistance, defined as the interaction of a center with a lone pair of electrons in an atom and the electrons present in aδor π bond. The researchful 1,2-dyotropic reactions, based on the 1,2-interchange of halogens, methyl and hydrogen taking place in a concerted fashion, are in competition with the two-step reaction in which the neighbouring group participation or anchimeric assistance comes to full expression by ionic dissociation of the other exchangeable (halogen) atom. As to be expected there is an essential difference between halogen or methyl exchange regarding the number of electrons participating in the transition state. This aspect becomes evident in the geometries of the corresponding transition state geometries. In this paper we refer to ab initio MO calculations and VB considerations. We consider the 1,2-halogen exchange as a combination of two SN2 reactions each containing four electrons. The van ’t Hoff dynamics appears a useful model in order to illustrate the computations in a straightforward manner.

2-A Cosmological Model with Varying G and ∧ in General Relativity  [PDF]
Harpreet  , R. K. Tiwari, H. S. Sahota
Open Journal of Applied Sciences (OJAppS) , 2013, DOI: 10.4236/ojapps.2013.31B1015
Abstract:

Spatially homogeneous and anisotropic Cosmological models play a significant role in the description of the early stages of evolution of the universe. The problem of the cosmological constant is still unsettled. The authors recently considered time dependent G and L with Bianchi type–I Cosmological model .We considered in this paper homogeneous Bianchi type -I space-time with variable G and L containing matter in the form of a perfect fluid assuming the cosmological term proportional to R-2 (where R is scale factor). Initially the model has a point type singularity, gravitational constant G (t) is decreasing and cosmological constant L is infinite at this time. When time increases L decreases. Unlike in some earlier works we have neither assumed equation of state nor particular form of G. The model does not approach isotropy, if ‘t’ is small .The model is quasi-isotropic for large value of ‘t’.

1-A Cosmological Model with Varying G and ∧ in General Relativity  [PDF]
Harpreet  , R. K. Tiwari, H. S. Sahota
Open Journal of Applied Sciences (OJAppS) , 2013, DOI: 10.4236/ojapps.2013.31B1018
Abstract:

In this paper homogeneous Bianchi type -I space-time with variable G and L containing matter in the form of a perfect fluid assuming the cosmological term proportional to H2 (where H is Hubble Parameter). Initially the model has a point type singularity, gravitational constant G (t) is decreasing and cosmological constant L is infinite at this time. When time increases,L decrease. The model does not approach isotropy, if it is small. The model is quasi-isotropic for large value of it.

Bulk Viscous Anisotropic Cosmological Models with Dynamical Cosmological Parameters G and ∧  [PDF]
S. Kotambkar, G. P. Singh, R. Kelkar
Natural Science (NS) , 2015, DOI: 10.4236/ns.2015.74021
Abstract: This paper deals with the Bianchi type I anisotropic models of the universe, filled with a bulk viscous cosmic fluid, in the presence of variable gravitational and cosmological constants. Some exact solutions of Einstein’s gravitational field equations with bulk viscosity, gravitational and cosmological constants have been obtained. Several well known forms of cosmological terms have been considered to discuss the effect of cosmological variables. The new cosmological models presented in this paper approaches to isotropic model with evolution of universe. The physical and dynamical properties of the models have also been discussed.
Parameter Estimations for Generalized RayleighDistribution under Progressively Type-I IntervalCensored Data  [PDF]
Y. L. Lio, Ding-Geng Chen, Tzong-Ru Tsai
Open Journal of Statistics (OJS) , 2011, DOI: 10.4236/ojs.2011.12006
Abstract: In this paper, inference on parameter estimation of the generalized Rayleigh distribution are investigated for progressively type-I interval censored samples. The estimators of distribution parameters via maximum likelihood, moment method and probability plot are derived, and their performance are compared based on simulation results in terms of the mean squared error and bias. A case application of plasma cell myeloma data is used for illustrating the proposed estimation methods.
LRS Bianchi Type-I Universe with Anisotropic Dark Energy in Lyra Geometry  [PDF]
Kishor S. Adhav
International Journal of Astronomy and Astrophysics (IJAA) , 2011, DOI: 10.4236/ijaa.2011.14026
Abstract: The exact solutions of the Einstein field equations for dark energy (DE) in Locally Rotationally Symmetric (LRS) Bianchi type-I metric under the assumption on the anisotropy of the fluid are obtained for exponential volumetric expansion within the frame work of Lyra manifold for uniform and time varying displacement field. The isotropy of the fluid and space is examined.
LRS Bianchi Type-I Cosmological Model with Anisotropic Dark Energy and Special Form of Deceleration Parameter  [PDF]
Kishor Shankarrao Adhav, Rajesh Purushottam Wankhade, Abhijit Shankarrao Bansod
Journal of Modern Physics (JMP) , 2013, DOI: 10.4236/jmp.2013.48139
Abstract:

We have studied Locally Rotationally Symmetric (LRS) Bianchi type-I cosmological model filled with anisotropic fluid in general theory of relativity. The solutions of the field equations are obtained by using special form of deceleration parameter which gives early deceleration and late time accelerating cosmological model. The geometrical and physical aspect of the model is also studied.

Effect of Bovine Type-I Collagen-Based Films Containing Red Propolis on Dermal Wound Healing in Rodent Model
Albuquerque-Júnior,Ricardo Luiz Cavalcanti de; Barreto,André Luiz Santos; Pires,J?natas Almeida; Reis,Francisco Prado; Lima,S?nia Oliveira; Ribeiro,Maria Amália Gonzaga; Cardoso,Juliana Cordeiro;
International Journal of Morphology , 2009, DOI: 10.4067/S0717-95022009000400025
Abstract: propolis, an apitherapic product widely employed in natural medicine, presents various biological properties, such as bactericidal and anti-inflammatory activities, but only few reports have looked at the brazilian red propolis variety. collagen films have been employed to improve wound healing and some studies have investigated the effect of natural products incorporated into these films. thus, the aim of this study was to analyze the effect of collagen-based films containing red propolis on wound healing. therefore, wounds performed in the back of rats were dressed with collagen-based films (g2), and collagen-based films containing red propolis (g3); undressed worked as control (g1). after 3, 7 and 14 days the animals were euthanized, and the wounds were microscopically evaluated. in 7 days, g3 showed switch of the inflammatory profile from acute into chronic, increased plasma cells differentiation, replacement of type-iii for type-i collagen fibers, and better architectural organization of those fibers. furthermore, a slight tendency for a better epithelization was verified in g3, but it was not statistically significant. also in 7 days, the microvessels count was higher in g1 than in g2 (p=0.000) and g3 (p=0.001), but similar between the last groups (p=0,15), whereas the microvessels perimeter was higher in g1 than in g2 (p=0.000) and g3 (p=0.002), but equivalent in g2 and g3 (p=0.175) in 14 days. in conclusion, the incorporation of brazilian red propolis into collagen-based films was able to improve wound healing, probably by modulating the dynamics of the inflammatory evolution and collagen deposition process.
Synthesis and high temperature thermoelectric transport properties of Si-based type-I clathrates

Deng Shu-Kang,Tang Xin-Feng,Tang Run-Sheng,

中国物理 B , 2009,
Abstract: N-type Si-based type-I clathrates with different Ga content were synthesized by combining the solid-state reaction method, melting method and spark plasma sintering (SPS) method. The effects of Ga composition on high temperature thermoelectric transport properties were investigated. The results show that at room temperature, the carrier concentration decreases, while the carrier mobility increases slightly with increasing Ga content. The Seebeck coefficient increases with increasing Ga content. Among all the samples, Ba$_{7.93}$Ga$_{17.13}$Si$_{28.72 }$exhibits higher Seebeck coefficient than the others and reaches $-135~\mu $V$\cdot$K$^{ - 1}$ at 1000 K. The sample prepared by this method exhibits very high electrical conductivity, and reaches 1.95$\times $10$^{5 }$~S$\cdot$m$^{ - 1}$ for Ba$_{8.01}$Ga$_{16.61}$Si$_{28.93}$ at room temperature. The thermal conductivity of all samples is almost temperature independent in the temperature range of 300--1000~K, indicating the behaviour of a typical metal. The maximum {ZT} value of 0.75 is obtained at 1000~K for the compound Ba$_{7.93}$Ga$_{17.13}$Si$_{28.72}$.
基于混合I型删失数据威布尔模型的可接受抽样计划
Acceptance Sampling Plans with Type-I Hybrid Censoring Scheme of Weibull Distribution
 [PDF]

李嘉伟
Advances in Applied Mathematics (AAM) , 2014, DOI: 10.12677/AAM.2014.34027
Abstract:
寿命是产品质量的一个重要指标。根据产品的寿命指标,用于确定产品的接受程度的可靠性试验,被称为可接受抽样计划。本文研究了基于混合I型删失数据的威布尔模型可接受抽样计划。首先,我们给出了威布尔分布尺度参数最大似然估计的精确分布。进而根据枢轴量的精确分布,在消费者与生产者风险可控的条件下,我们给出了可接受抽样计划的执行方法。最后为了展示本文的方法,我们给出了一些可接受抽样计划的数值模拟结果。
Lifetime is an important quality variable of a product. Sampling plans used to determine the ac-ceptability of a product, with respect to its lifetime, are known as acceptance sampling plans. In this paper, we discuss acceptance sampling plans of Weibull distribution with considering the Type-I hybrid censoring schemes. Firstly, we give the exact conditional distribution of the maximum likelihood estimator (MLE) of the scale parameter. Secondly, using the exact distribution of a pivotal quantity, we establish an acceptance sampling procedure satisfying the producer and consumer risks. Finally, some numerical results are tabulated for illustration.
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