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排序方式: 共有458条查询结果,搜索用时 15 毫秒
101.
AM Chinnaiyan WL Hanna K Orth H Duan GG Poirier CJ Froelich VM Dixit 《Canadian Metallurgical Quarterly》1996,6(7):897-899
Cytotoxic T lymphocytes (CTLs) and natural killers (NK) cells provide immune surveillance against viruses and neoplasms, and play a central role in the pathogenesis of autoimmune disease, AIDS and graft rejection. Thus, it is important to understand the precise molecular mechanism(s) whereby cytotoxic lymphocytes destroy susceptible target cells. Granule-mediated cytotoxicity requires a combination of both perforin and granzyme B. Perforin polymerizes to form transmembrane channels and presumably allows granzyme B access to target cell substrates, which until recently, were unknown. One clue to the identity of the physiological substrate(s) activated by granzyme B comes from its unusual specificity for cleaving synthetic substrates after aspartate residues. Members of the ICE/CED-3 family of cysteine proteases are prime candidates as they are important apoptotic effectors and are expressed as zymogens, which can be processed to form active heterodimeric enzymes after cleavage at specific aspartate residues. Previous studies have shown that granzyme B proteolytically activates the cell death effector Yama/CPP32/apopain (referred to here as Yama). Here we report that granzyme B also activates ICE-LAP3/Mch3/CMH-1 (referred to here as ICE-LAP3), which, along with Yama and Mch2, forms a subset of the ICE/CED-3 family of cysteine proteases most closely related to the Caenorhabditis elegans cell death gene, CED-3. Importantly, Jurkat T cells incubated with granzyme B and a sublytic concentration of perforin undergo apoptosis, which is preceded by the activation of endogenous ICE-LAP3. Thus, we propose that granzyme B mediates apoptosis by directly engaging the target cell's death effector machinery, which is probably composed of an arsenal of intracellular, CED-3-like cysteine proteases. 相似文献
102.
Customer involvement plays a crucial role in engineered-to-order (ETO) projects. The present study investigates the involvement of customers, with thorough technical knowledge, as resources and co-producers. The study also analyses the impact of customer involvement in sourcing decisions and project execution on project performance (PP) of ETO shipbuilding projects by considering project and customer characteristics. The contributions of this study to the current body of knowledge on customer involvement in ETO projects are twofold. First, it demonstrates that customer involvement at different stages of shipbuilding projects have differential impacts on PP. Customer involvement in sourcing decisions during the early stages of the project has a positive impact, whereas involvement in project execution during the later stages of the project has a negative impact on PP. Second, it reveals that project complexity and customer type together significantly affect the PP. Therefore, the role of project complexity and customer type as potential contingent factors in explaining PP is emphasised. This study also makes a significant methodological contribution by demonstrating the use of fuzzy inference system and rough set theory to analyse qualitative inputs from interviews, when conducting surveys is not possible. 相似文献
103.
Anuj Kumar Sharma Arun Kumar Tiwari Amit Rai Dixit 《Materials and Manufacturing Processes》2015,30(7):813-828
A colloidal mixture of nanometer-sized (<100 nm) metallic and non-metallic particles in conventional cutting fluid is called nanofluid. Nanofluids are considered to be potential heat transfer fluids because of their superior thermal and tribological properties. Therefore, nano-enhanced cutting fluids have recently attracted the attention of researchers. This paper presents a summary of some important published research works on the application of nanofluid in different machining processes: milling, drilling, grinding, and turning. Further, this review article not only discusses the influence of different types of nanofluids on machining performance in various machining processes but also unfolds other factors affecting machining performance. These other factors include nanoparticle size, its concentration in base fluid, lubrication mode (minimum quantity lubrication and flood), fluid spraying nozzle orientation, spray distance, and air pressure. From literature review, it has been found that in nanofluid machining, higher nanoparticle concentration yields better surface finish and more lubrication due to direct effect (rolling/sliding/filming) and surface enhancement effect (mending and polishing) of nanoparticles compared to dry machining and conventional cutting fluid machining. Furthermore, nanofluid also reduces the cutting force, power consumption, tool wear, nodal temperature, and friction coefficient. Authors have also identified the research gaps for further research. 相似文献
104.
N.S. Dixit N. Venkatramani V.K. Rohatgi 《International Journal of Heat and Mass Transfer》1987,30(12):2617-2625
The electrical conductivity of the working medium of a combustion driven MHD generator is increased by introducing a low-ionization potential additive (seed). This seed is in the form of a fine spray of an aqueous solution of K2CO3 by an atomizer. However, the electrical conductivity depends strongly on the evaporation process and the evaporation in turn depends on the size of droplets. In this paper, the effect of seed droplet size on evaporation (and hence on electrical conductivity and plasma temperature) have been analysed by formulating a single step finite rate evaporation model. Experiments were conducted to measure plasma temperature and conductivity on a potassium seeded combustion plasma system by introducing seed droplets of different sizes. The measured and the predicted values have been compared to substantiate the model. 相似文献
105.
Sanjay Dwivedi A. Mishra A. Kumar P. Tripathi R. Dave G. Dixit K. K. Tiwari S. Srivastava M. K. Shukla R. D. Tripathi 《Clean Technologies and Environmental Policy》2012,14(2):223-228
During the present study, two species of Portulaca, i.e., P. tuberosa and P. oleracea were collected from two field sites in Vadodara, Gujarat, India; one irrigated with industrial effluent and other with tube
well water, and were analyzed for heavy metal accumulation in different plant parts viz., roots, stem, leaves, and flowers.
Plants collected from effluent irrigated areas showed high accumulation of all the investigated heavy metals in all plant
parts with the maximum being in roots and the least in flowers. Interestingly, both species of Portulaca demonstrated hyperaccumulation of multiple elements viz., Cu, Ni, Hg, and Pb. The total shoot concentrations (μg g−1 dw) of Cu, Ni, Hg, and Pb in P. tuberosa were 1538, 1191, 789, and 2744, respectively, while in P. oleracea, these were 1940, 1542, 534, and 2312, respectively. Besides this, selective hyperaccumulation of Se (2,327 μg g−1 dw) and Al (1,164 μg g−1 dw) was shown by P. tuberosa and P. oleracea, respectively. Total shoot concentrations (μg g−1 dw) of Mo were about 399 and 668 in P. tuberosa and P. oleracea, respectively. Overall, P. oleracea accumulated higher amounts of multiple metals from industrial effluent contaminated site, hence appears to be a suitable
candidate for phytoremediation purposes of metal contaminated areas. 相似文献
106.
107.
Kannojia Harindra Kumar Sidhique Aboobackkar Shukla Ambika Shanker Pednekar Jaising Gupta Shalabh Dixit Pradeep 《Microsystem Technologies》2022,28(4):955-964
Microsystem Technologies - Design and fabrication of the through-glass via (TGV) based three-dimensional (3D) spiral inductors in the fused silica substrates by a simpler electrochemical discharge... 相似文献
108.
Bharat Chandrashekhar Dixit Ritu B. Dixit Dhirubhai J. Desai 《Journal of Polymer Research》2010,17(4):481-488
Novel ion-exchange resin (PBMDDMCMHQ polyimide) having 8-hydroxyuinoline as a pendent groups was prepared using phenylenebismaleimide-diamine polyimide (PBMDDM) and 5-chloromethyl-8-hydroxyquinoline hydrochloride (CMHQ). Phenylenebismaleimide-diamine polyimide (PBMDDM) was prepared by Michael addition reaction of 1,3-phenylenebismaleimide (PBM) and 4,4’-diaminodiphenyl methane (DDM). The resulting ion-exchange resin was characterized by spectral techniques. Polymeric metal chelates of ion-exchange resin were also prepared using transition metal ions Zn(II), Cu(II), Ni(II), Co(II) and Mn(II), and were duly characterized. Ion-exchange properties of ion-exchange resin (PBMDDMCMHQ) for Fe(III), Zn(II), Ni(II) and Cu(II) metal ions were also studied by batch-equilibration method. The produced ion-exchange resin (PBMDDMCMHQ) has thermal stability up to 220°C and can be used over a wide pH range. It has good metal up take capacity at varying pH range and can be recycled. 相似文献
109.
Jammu and Kashmir the northern most state of India is blessed with immense potential for utilization of renewable energy. The state at present is fairly untapped in terms of energy utilization and thus venturing into this region would definitely prove to be profitable. The natural energy sources like sunshine, wind, vegetation, water flow, biomass and other biological wastes though abundantly available in the state yet are not being potentially harnessed resulting in very low per capita energy availability, deforestation and poor health. Renewable energy acquires a promising option not only for energy availability next view and of environment protection but also the socio-economic conditions of the people residing in these areas can be improved to a great extent. The hydroelectric power has tremendous potential for generation of electricity in the state because the topography of the state provides extensive network of canals and streams. This paper describes the resource potential and opportunity to enter the market and bring more renewable energy projects in the form of solar, biomass derived fuels, biogas and hydroelectric in the state. 相似文献
110.
Apoptosis induction by caspase-8 is amplified through the mitochondrial release of cytochrome c 总被引:1,自引:0,他引:1
T Kuwana JJ Smith M Muzio V Dixit DD Newmeyer S Kornbluth 《Canadian Metallurgical Quarterly》1998,273(26):16589-16594
Apoptosis often involves the release of cytochrome c from mitochondria, leading to caspase activation. However, in apoptosis mediated by CD95 (Fas/APO-1), caspase-8 (FLICE/MACH/Mch5) is immediately activated and, in principle, could process other caspases directly. To investigate whether caspase-8 could also act through mitochondria, we added active caspase-8 to a Xenopus cell-free system requiring these organelles. Caspase-8 rapidly promoted the apoptotic program, culminating in fragmentation of chromatin and the nuclear membrane. In extracts devoid of mitochondria, caspase-8 produced DNA degradation, but left nuclear membranes intact. Thus, mitochondria were required for complete engagement of the apoptotic machinery. In the absence of mitochondria, high concentrations of caspase-8 were required to activate downstream caspases. However, when mitochondria were present, the effects of low concentrations of caspase-8 were vastly amplified through cytochrome c-dependent caspase activation. Caspase-8 promoted cytochrome c release indirectly, by cleaving at least one cytosolic substrate. Bcl-2 blocked apoptosis only at the lowest caspase-8 concentrations, potentially explaining why CD95-induced apoptosis can often evade inhibition by Bcl-2. 相似文献