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21.
We recently described our finding that recombinant baculovirus-produced virus-like particles (VLPs) can induce cell-cell fusion similar to that induced by intact rotavirus in our assay for viral entry into tissue culture cells (J. M. Gilbert and H. B. Greenberg, J. Virol. 71:4555-4563, 1997). The conditions required for syncytium formation are similar to those for viral penetration of the plasma membrane during the course of viral infection. This VLP-mediated fusion activity was dependent on the presence of the outer-layer proteins, viral protein 4 (VP4) and VP7, and on the trypsinization of VP4. Fusion activity occurred only with cells that are permissive for rotavirus infection. Here we begin to dissect the role of VP4 in rotavirus entry by examining the importance of the precise trypsin cleavage of VP4 and the activation of VP4 function related to viral entry. We present evidence that the elimination of the three trypsin-susceptible arginine residues of VP4 by specific site-directed mutagenesis prevents syncytium formation. Two of the three arginine residues in VP4 are dispensable for syncytium formation, and only the arginine residue at site 247 appears to be required for activation of VP4 functions and cell-cell fusion. Using the recombinant VLPs in our syncytium assay will aid in understanding the conformational changes that occur in VP4 involved in rotavirus penetration into host cells. 相似文献
22.
23.
M Tolnay A Probst AU Monsch HB Staehelin R Egensperger 《Canadian Metallurgical Quarterly》1998,96(3):225-227
Glanzmann's thrombasthenia is a rare inherited hematological disorder defined by deficiency or abnormality of the glycoprotein (GP) IIb-IIIa complex. Presenting symptoms are hemorrhagic events, mainly epistaxis, purpura, or menorrhagia. We describe the clinical course and management of a 14-year-old girl with Glanzmann's thrombasthenia and severe menorrhagia. Following treatment with 20 U of packed red blood cells, 37 U of platelets, 7 U of fresh frozen plasma, cryoprecipitate, intravenous estrogens, and methylergotrine maleate with no improvement, the uterine cavity was packed for 48 hr. This unusual procedure halted the bleeding and avoided the necessity for a hysterectomy. When treating acute menorrhagia in patients with Glanzmann's thrombasthenia, the physician should be familiar with the characteristics and all treatment modalities for this disorder. 相似文献
24.
A model for predicting film thickness profiles around topographical features during spin coating is presented. This model is applicable to features of arbitrary geometry in the two lateral dimensions. This generally permits study of the planarization of real device structures, including both isolated and neighboring features, with any orientation with respect to the wafer center. Predictions from this model agree qualitatively with measured thin-film profiles from interferograms taken during spinning. Phenomena such as pile-up and wakes result from interactions between surface tension and other driving forces in the flow 相似文献
25.
Hysteresis effects are reported for ZrO2 oxygen sensors exposed to non-equilibrium oxygen/hydrocarbon gas mixtures. With oxygen/toluene at 800° C, voltage-composition curves differ following composition changes (a) from excess oxygen to excess toluene and (b) from excess toluene to excess oxygen. A catalysis model is developed to account for this behaviour: the Thiele modulus of the catalyst/electrode is presumed to differ under (a) net oxidizing and (b) net reducing conditions. Large scale voltage fluctuations, sometimes exceeding 400 mV, were observed in experiments with oxygen/isobutane mixtures at 600° C. This behaviour is analysed in terms of a kinetic model involving stochastic variations of relative mass transfer coefficients of oxygen and isobutane. 相似文献
26.
普遍称为Benzofuroxan(BFO)的苯并呋咱-1-氧化物已证明能降低填充炭黑的硫化胶的滞后损失30%以上。BFO大概能促进弹性体和炭黑之间的键合,导致硫化胶“佩恩效应”降低。BFO在母炼胶混炼期间于不同温度下加入。为了最大限度地降低滞后损失,需要高温混炼,而且采用高比表面积的炭黑会更有效。镍盐会改善BFO和弹性体/炭黑间的反应。 相似文献
27.
HB Wielandt 《Canadian Metallurgical Quarterly》1994,156(10):1438-1441
In October 1989 a representative sample consisting of 359 women (response rate = 77.9%) and 400 men (response rate = 76.3%) aged 16-20 years old was interviewed by the professional interviewer staff of the Institute for Social Research. The purpose of the investigation was to illustrate whether AIDS and "Safe sex"-campaigns have influenced young people. This paper consider the attitudes to contraception among teenagers. Generally, the reports are in accordance with an increasing popularity of the condom. Almost all answered that it was all right for a girl to bring a condom. The majority (313 (89.4%) among women and 311 (78.7%) among men) reported both partners to be responsible in relation to contraception. Still, it is commonly the female who brings up the question. Communication about contraception between the female and the male partner is of importance in order to impede sexually transmitted diseases and reduce the number of legally induced abortions among teenagers. The widespread attitude towards contraception as being a joint concern forms an appropriate basis to attain equality between the sexes in relation to communication about contraception. 相似文献
28.
In this research, we model a job shop that produces a set of discrete parts in a make-to-stock setting. The intent of the research is to develop a planning model to determine the optimal tactical policies that minimise the relevant manufacturing costs subject to workload variability and capacity limits. We consider two tactical decisions, namely the production lot size for each part and the planned lead time for each work station. We model the relevant manufacturing costs, entailing production overtime costs and inventory-related costs, as functions of these tactical decisions. We formulate a non-linear optimisation model and implement it in the Excel spreadsheet. We test the model with actual factory data from our research sponsor. The results are consistent with our intuition and demonstrate the potential value from jointly optimising over these tactical policies. 相似文献
29.
Direct Observation of Localized Radial Oxygen Migration in Functioning Tantalum Oxide Memristors
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30.
Alan Davis Sean Graves Terry Murray 《Journal of The Association for Laboratory Automation》2001,6(6):28-31
The genomics, proteomics, clinical, and drug discovery laboratories have a growing need to maintain valuable samples at ultra-low (−80°C) temperatures in a validated, secure environment. Automated sample processing systems have until now required manual (off-line) storage of samples at −80°C, reducing system reliability and speed. Both of these important needs are addressed by the Sample Process Management System being introduced by BIOPHILE Inc. Conventional sample management processes, such as storage, retrieval, and cataloging, are increasingly strained by the growing sample populations. There are variable sample types, access requirements and storage requirements. Security and inventory procedures are implemented manually. The evolving technologies present in the laboratory cannot interface with conventional manual storage techniques. Addressing these limitations, the primary benefits of BIOPHILE's solutions are:
- • Fully validated sample management process that coordinates the life-cycles of samples and their related data.
- • Robotic technology to securely store and retrieve samples, improving their accessibility and stability. Thermal shock is reduced, improving sample longevity and quality. The robotic technology allows integration with larger automation systems.
- • A process program to develop a Sample Management Strategy. This strategy is developed by analyzing long-term research goals, current baseline processes, and identification of current sample life cycles. A full validation documentation package can be generated, providing a high level of quality assurance.
- • Improved sample visibility and quality assurance - automated sample population cataloging; controlled sample management access and security.