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91.
Life-long viral persistence is a hallmark of human herpesvirus infection. In the Epstein-Barr virus (EBV)-positive Burkitt's lymphoma (BL) cell line, Mutu, spontaneous loss of all viral episomes accompanied productive viral DNA replication. The molecular configuration of intracellular EBV DNA evolved from monoclonal episomes in cells retaining the original tumor phenotype to predominantly replicating linear DNA and, subsequently, only integrated forms in BL cells that had acquired the lymphoblastoid cell phenotype. Transient appearance of deleted, rearranged WZhet EBV DNA capable of disrupting viral latency, along with the integration of viral DNA into human chromosomes, indicates a genetic instability in the host cell which, if duplicated in vivo, may affect configuration and persistence of the viral genome in expanding malignant cell clones. 相似文献
92.
This paper presents a finite element-based model for the prediction of 2-D and 3-D internal flow problems. The Eulerian velocity
correction method is used which can render a fast finite element code comparable with the finite difference methods. Nine
different models for turbulent flows are incorporated in the code. A modified wall function approach for solving the energy
equation with high Reynolds number models is presented for the first time. This is an extension of the wall function approach
of Benim and Zinser and the method is insensitive to initial approximation. The performance of the nine turbulent models is
evaluated by solving flow through pipes. The code is used to predict various internal flows such as flow in the diffuser and
flow in a ribbed channel. The same Eulerian velocity correction method is extended to predict the 3-D laminar flows in various
ducts. The steady state results have been compared with benchmark solutions and the agreement appears to be good. 相似文献
93.
94.
95.
Vikas G. Sadvilkar Srinivas D. Samant Vilas G. Gaikar 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1995,62(4):405-410
The Claisen–Schmidt condensation of benzaldehydes with acetophenones was carried out in an aqueous medium using sodium butylmonoglycolsulfate (NaBMGS) and sodium salts of aromatic sulfonic acids as hydrotropes. Substantial enhancement in the rate of the reaction was obtained, along with the easy recovery of the product. Recycling of the hydrotrope solutions has been tested without any loss in the rate of the reaction. 相似文献
96.
GR Srinivas CO Chichester HJ Barrach V Pillai AL Matoney 《Canadian Metallurgical Quarterly》1994,23(2):85-98
Immunoassays are used for the specific measurement of type II collagen, a major cartilage protein, which is lost in osteoarthritic joints. Poor immunogenicity and species dependent immune response to type II collagen make it difficult to obtain specific antibodies required for immunoassay development. In addition, type II collagen antibodies exhibit reactivity to structurally dissimilar antigens such as actin, myoglobin, thyroglobulin and ssDNA, complicating the isolation of specific antibodies. It is therefore necessary to characterize the antibody reactivity against both noncollagenous antigens and different collagen types. In this study, immune response to type II collagen was improved by conjugation to carrier proteins, KLH and BSA. Hybridomas were generated by fusions of lymphocytes derived from lymph nodes or spleens with X63-653-Ag8 myeloma cells. Compared to spleens, the utilization of lymph nodes as a source of lymphocytes resulted in a 23% higher number of hybridomas secreting type II collagen antibodies. Hybridomas secreting polyreactive antibodies were identified based on their reactivity to thyroglobulin and eliminated. Extensive testing of the remaining monoclonal antibodies with other structurally dissimilar antigens and various types of collagen for reactivity, allowed us to isolate specific monoclonal antibodies to type II collagen. We emphasize the importance of characterization of the reactivity of type II collagen monoclonal antibodies before employing them for immunoassays. 相似文献
97.
The diffusion, stability and monotonicity properties of the first order local stability scheme are investigated by resorting to both analysis and numerical experimentation. The scheme, deducible from either the first order Rusanov scheme or the first order van Leer scheme, is optimally stable. The magnitude of the truncation viscosity of the scheme is in between that of the Rusanov scheme and of the second order Lax-Wendroff scheme. The scheme does not, in general, yield monotonic profiles of shocks. A modified version of the local stability scheme (which preserves the local stability character at each point in the flow region and switches over to the van Leer scheme near shocks only) is proposed for practical application. Tests on one-dimensional problems show that the scheme achieves a better resolution of the flow features than is possible with the Rusanov scheme. The scheme is found to be capable of yielding a resolution which is almost equal to that of the second order schemes. Furthermore, it offers other advantages in that it resists nonlinear instabilities, is easy to programme and requires only a modest amount of storage and time on the computer. 相似文献
98.
A model is developed to study the intraparticle effects of char combustion which incorporates the reactions, C + 1/202 → CO, CO + 1/202 → CO2 and CO2 + C → 2CO with appropriate intrinsic kinetics. Based on some limiting cases a feasibility region, inside which the solution should lie, is developed. In almost all cases the major product is CO with CO2 production 2 to 3 orders of magnitude lower. A maximum of three steady states is observed for the parameters chosen. The combustion rate decreases with increase in particle size and increase in boundary layer thickness. The solution structure depends strongly on the radiation conditions which obtain and on the transport properties inside the particle. The purpose of this study is to determine the effect of intraparticle transport without the confounding effects of other phenomena. 相似文献
99.
KambalaV Subba Rao Basavaraju Srinivas Pierre Boule Machiraju Subrahmanyam 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2002,77(5):568-575
Regioselective photooxidative demethylation of methyl‐substituted N‐containing heterocyclic compounds is investigated in non‐aqueous (ethane nitrile) solutions containing semiconductor oxide (TiO2) as photocatalyst in the presence of molecular oxygen upon irradiation at room temperature conditions. A plausible electron transfer mechanism, in which an electron‐hole pair is generated on the surface of TiO2 by illumination, is proposed for the semiconductor‐mediated photocatalysis. Molecular orbital calculation by the AM 1 method has been performed for the electron densities of N‐atoms of heterocyclics in the present study. © 2002 Society of Chemical Industry 相似文献
100.
In this paper an anlytical model for the calculation of the pressure pulse in hexagonal ducts due to discharge of gas from a failed fuel pin is developed. The analysis yields the time history of the pressure pulse which can be used in the calculation of permanent deformation of the duct or in the assessment of the susceptibility of the duct to fracture. In this model the analysis is divided into two stages. In the first stage the gas expands as a spherical bubble, but the influence of duct wall is taken into account. At the end of the first stage the spherical shape of the bubble is assumed to be lost and the gas is assumed to expand axially as a column. The end conditions of stage 1 are the initial conditions for stage 2. The analysis involves solving the continuity and momentum equations for the liquid along with the energy balance equation for the gas. In the analysis the liquid is assumed to be incompressible. 相似文献