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31.
Kinetic studies on the reduction of iron ore nuggets by devolatilization of lean-grade coal
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Chanchal Biswas Prithviraj Gupta Arnab De Mahua Ghosh Chaudhuri Rajib Dey 《矿物冶金与材料学报》2016,23(12):1360-1368
An isothermal kinetic study of a novel technique for reducing agglomerated iron ore by volatiles released by pyrolysis of lean-grade non-coking coal was carried out at temperature from 1050 to 1200°C for 10–120 min. The reduced samples were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and chemical analysis. A good degree of metallization and reduction was achieved. Gas diffusion through the solid was identified as the reaction-rate-controlling resistance; however, during the initial period, particularly at lower temperatures, resistance to interfacial chemical reaction was also significant, though not dominant. The apparent rate constant was observed to increase marginally with decreasing size of the particles constituting the nuggets. The apparent activation energy of reduction was estimated to be in the range from 49.640 to 51.220 kJ/mol and was not observed to be affected by the particle size. The sulfur and carbon contents in the reduced samples were also determined. 相似文献
32.
Poisson integer‐valued auto‐regressive process of order 1 (PINAR(1)) due to Al‐Osh and Alzaid (Journal of Time Series Analysis 1987; 8 (3): 261–275) and McKenzie (Advances in Applied Probability 1988; 20 (4): 822–835) has received a significant attention in modelling low‐count time series during the last two decades because of its simplicity. But in many practical scenarios, the process appears to be inadequate, especially when data are overdispersed in nature. This overdispersion occurs mainly for three reasons: presence of some extreme values, large number of zeros, and presence of both extreme values with a large number of zeros. In this article, we develop a zero‐inflated Poisson INAR(1) process as an alternative to the PINAR(1) process when the number of zeros in the data is larger than the expected number of zeros by the Poisson process. We investigate some important properties such as stationarity, ergodicity, autocorrelation structure, and conditional distribution, with a detailed study on h‐step‐ahead coherent forecasting. A comparative study among different methods of parameter estimation is carried out using some simulated data. One real dataset is analysed for practical illustration. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
33.
Draper-dependent glial phagocytic activity is mediated by Src and Syk family kinase signalling 总被引:1,自引:0,他引:1
Ziegenfuss JS Biswas R Avery MA Hong K Sheehan AE Yeung YG Stanley ER Freeman MR 《Nature》2008,453(7197):935-939
The cellular machinery promoting phagocytosis of corpses of apoptotic cells is well conserved from worms to mammals. An important component is the Caenorhabditis elegans engulfment receptor CED-1 (ref. 1) and its Drosophila orthologue, Draper. The CED-1/Draper signalling pathway is also essential for the phagocytosis of other types of 'modified self' including necrotic cells, developmentally pruned axons and dendrites, and axons undergoing Wallerian degeneration. Here we show that Drosophila Shark, a non-receptor tyrosine kinase similar to mammalian Syk and Zap-70, binds Draper through an immunoreceptor tyrosine-based activation motif (ITAM) in the Draper intracellular domain. We show that Shark activity is essential for Draper-mediated signalling events in vivo, including the recruitment of glial membranes to severed axons and the phagocytosis of axonal debris and neuronal cell corpses by glia. We also show that the Src family kinase (SFK) Src42A can markedly increase Draper phosphorylation and is essential for glial phagocytic activity. We propose that ligand-dependent Draper receptor activation initiates the Src42A-dependent tyrosine phosphorylation of Draper, the association of Shark and the activation of the Draper pathway. These Draper-Src42A-Shark interactions are strikingly similar to mammalian immunoreceptor-SFK-Syk signalling events in mammalian myeloid and lymphoid cells. Thus, Draper seems to be an ancient immunoreceptor with an extracellular domain tuned to modified self, and an intracellular domain promoting phagocytosis through an ITAM-domain-SFK-Syk-mediated signalling cascade. 相似文献
34.
A. Chaudhuri D. Ghosh A. K. Chatterjee N. M. Biswas P. K. Ghosh 《Cellular and molecular life sciences : CMLS》1991,47(1):86-88
Summary Removal of the ventral prostate gland in adult male rats causes an increase in adrenal weight, and stimulation of adrenal
5-3-hydroxysteroid dehydrogenase activity along with elevation of serum levels of corticosterone and prolactin. 相似文献
35.
Decreased expression of the insulin-responsive glucose transporter in diabetes and fasting 总被引:23,自引:0,他引:23
Cellular resistance to insulin caused by a reduction in insulin-mediated glucose uptake can be produced in rats by chemically inducing diabetes with streptozotocin and by fasting. Two glucose transporter isoforms are expressed in fat cells: (1) the insulin-responsive species which is found only in fat and muscle, and (2) a species corresponding to the erythrocyte/Hep G2/rat brain transporter. We show here that fat cells isolated from streptozotocin diabetic rats and from fasted rats show a significant (60-80%) decrease in the amount of immunologically detectable insulin-sensitive glucose transporter and no change in the level of the Hep G2/rat brain transporter. Administration of insulin and refeeding, respectively, result in a return of the insulin-sensitive glucose transporter to levels that are normal or slightly above normal. Thus, peripheral tissue insulin resistance could be due to the specific reduction in the amount of insulin-sensitive glucose transporter. 相似文献
36.
Résumé La dégénération des testicules des rats nourris d'une dose toxique de « tyrosine » a été évitée par le traitement à l'acide ascorbique. 相似文献
37.
Zusammenfassung Unter dem Einfluss der Indolessigsäure ist die Aminoacyl-SRNA-Synthese nicht verändert, dagegen zeigen die Ribosomen eine gesteigerte Fähigkeit von Aminosäure-Inkorporation. 相似文献
38.
Zusammenfassung Es scheint, dass DNase und RNase bei der photosynthetischen Fixierung des CO2 verschiedene und komplizierte Wirkung ausüben. Die Saccharaose-Synthese wird durch die Behandlung mit DNase und RNase deutlich vermindert. 相似文献
39.
S. Ghosal D. K. Chakrabarti K. Biswas Y. Kumar 《Cellular and molecular life sciences : CMLS》1979,35(12):1633-1634
Summary Accumulation of mangiferin and degraded carotenoids, in response toFusarium moniliforme infection, has been suggested to be responsible for the malformation disease ofMangifera indica L. (Anacardiaceae).Acknowledgments. The authors are indebted to the University Grants Commission, New Delhi, for financial assistance to carry out this project. 相似文献