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31.
In the present paper, we have investigated the high-pressure structural phase transition of divalent metal oxides using the three-body potential modified by incorporating the covalency effects. Phase transition pressures are associated with a sudden collapse in volume. The phase transition pressures and associated volume collapses obtained from present potential model show a generally better agreement with available experimental data than others. The elastic constants and their pressure derivatives are also reported. It is found that the present model has a promise to predict the phase transition pressure and, the elastic constants and their pressure derivatives of other chalcogenides as well. Moreover the thermophysical properties have also been obtained successfully. 相似文献
32.
E. G. Rini N. K. Gaur V. Shelke J. Galgale M. P. Verma R. K. Singh 《Journal of Superconductivity》2002,15(6):583-585
We have developed a shell model, which includes the long-range coulomb, van der Waals interaction, and the short-range Hafemeister–Flygare repulsive interaction operative up to second neighbor atom to study the cohesive and thermal properties of LaMnO3 + . The results on cohesive energy obtained by us are in good agreement with that of calculated value by DeSouza et. al. (R. A. DeSouza, M. S. Islam, and E. I. Tiffee, J. Mater. Chem.
9, 1621 (1999)). In addition, we have also calculated molecular force constant (f), compressibility (), restrahlen frequency (o), Debye temperature (D), and the low temperature specific heat at 50 K T 160 K. Our results on Debye temperature and specific heat for the temperature range 50 K T 160 K are closer to the recently measured data with an automated quasi-adiabatic pulse technique. 相似文献
33.
Yeoh T.S. Swint R.B. Gaur A. Elarde V.C. Coleman J.J. 《IEEE journal of selected topics in quantum electronics》2002,8(4):833-838
We report results of both strain-driven surface segregation of indium from InGaAs thin films as well as selective area epitaxy of InAs quantum dots using these films. InAs segregation from an underlying InGaAs film allows for preferential growth of quantum dots when additional InAs is deposited. By using standard lithography techniques, a two-step selective growth process for quantum dots is achieved. Furthermore, by utilizing self-assembled nanostructures as a template, selective growth of coalesced wires and dots with 100-nm feature sizes are realized. 相似文献
34.
L Ohno-Machado JH Gennari SN Murphy NL Jain SW Tu DE Oliver E Pattison-Gordon RA Greenes EH Shortliffe GO Barnett 《Canadian Metallurgical Quarterly》1998,5(4):357-372
Carboxylate and sulfate groups were introduced at the surface of poly(ethylene) (PE) samples. This was accomplished by coating and immobilizing sodium 10-undecenoate (C11(:)) and 10-undecene sulfate (S11(:)) on the polymer by means of an argon plasma treatment. The composition of the coated surfactant layer was proportional to the composition of the coating solution. The thickness of the surfactant layer on the surface of PE samples, which were precoated from an aqueous solution with a total surfactant concentration of 0.30 M, was about 55 A. The presence of carboxylate and sulfate groups after plasma treatment of the precoated surfaces was confirmed by X-ray photoelectron spectroscopy (XPS). About 20% of the initial amount of functional groups of the coated surfactants was retained at the PE surface. The ratio of carboxylate/sulfate groups at the plasma treated surfaces was dependent on the composition of the precoated surfaces. The minimum surface density of these groups on the resulting samples was about one group per 40 A2. 相似文献
35.
AE Medvedev T Flo RR Ingalls DT Golenbock G Teti SN Vogel T Espevik 《Canadian Metallurgical Quarterly》1998,160(9):4535-4542
This study was undertaken to evaluate the role of CD14 and complement receptors type 3 (CR3) and 4 (CR4) in mediating TNF release and NF-kappaB activation induced by LPS and cell wall preparations from group B streptococci type III (GBS). LPS and GBS caused TNF secretion from human monocytes in a CD14-dependent manner, and soluble CD14, LPS binding protein, or their combination potentiated both LPS- and GBS-induced activities. Blocking of either CD14 or CD18, the common beta-subunit of CR3 and CR4, decreased GBS-induced TNF release, while LPS-mediated TNF production was inhibited by anti-CD14 mAb only. Chinese hamster ovary cell transfectants (CHO) that express human CD14 (CHO/CD14) responded to both LPS and GBS with NF-kappaB translocation, which was inhibited by anti-CD14 mAb and enhanced by LPS binding protein. While LPS showed fast kinetics of NF-kappaB activation in CHO/CD14 cells, a slower NF-kappaB response was induced by GBS. LPS also activated NF-kappaB in CHO cells transfected with either human CR3 or CR4 cDNA, although responses were delayed and weaker than those of CHO/CD14 cells. In contrast to LPS, GBS failed to induce NF-kappaB in CHO/CR3 or CHO/CR4 cells. Both C3H/OuJ (Lps[n]) and C3H/HeJ (Lps[d]) mouse peritoneal macrophages responded to GBS with TNF production and NF-kappaB translocation, whereas LPS was active only in C3H/OuJ macrophages. Thus, LPS and GBS differentially involve CD14 and CR3 or CR4 for signaling NF-kappaB activation in CHO cells and TNF release in human monocytes, and engage a different set of receptors and/or intracellular signaling pathways in mouse macrophages. 相似文献
36.
Zinc has an important place amongst inhibitors of crystallisation and crystal growth. These views are supported by in vivo and in vitro studies which suggest that the urinary zinc level is a significant factor in urolithiasis. Some recent studies have given contradictory results. Blood serum and urinary zinc levels were measured in 30 normal healthy controls and 42 stone forming patients (renal, ureteric and vesical). Statistically significant levels were found in all groups, varying according to the number of calculi. Increased urinary zinc levels and decreased serum zinc levels appear to be secondary to the process of stone formation. The role of zinc as an inhibitor of urolithiasis is questionable. 相似文献
37.
JJ Gao MB Filla MJ Fultz SN Vogel SW Russell WJ Murphy 《Canadian Metallurgical Quarterly》1998,161(9):4803-4810
38.
IM Bell JM Erb RM Freidinger SN Gallicchio JP Guare MT Guidotti RA Halpin DW Hobbs CF Homnick MS Kuo EV Lis DJ Mathre SR Michelson JM Pawluczyk DJ Pettibone DR Reiss S Vickers PD Williams CJ Woyden 《Canadian Metallurgical Quarterly》1998,41(12):2146-2163
The previously reported oxytocin antagonist L-371,257 (2) has been modified at its acetylpiperidine terminus to incorporate various pyridine N-oxide groups. This modification has led to the identification of compounds with improved pharmacokinetics and excellent oral bioavailability. The pyridine N-oxide series is exemplified by L-372,662 (30), which possessed good potency in vitro (Ki = 4.1 nM, cloned human oxytocin receptor) and in vivo (intravenous AD50 = 0.71 mg/kg in the rat), excellent oral bioavailability (90% in the rat, 96% in the dog), good aqueous solubility (>8.5 mg/mL at pH 5.2) which should facilitate formulation for iv administration, and excellent selectivity against the human arginine vasopressin receptors. Incorporation of a 5-fluoro substituent on the central benzoyl ring of this class of oxytocin antagonists enhanced in vitro and in vivo potency but was detrimental to the pharmacokinetic profiles of these compounds. Although lipophilic substitution around the pyridine ring of compound 30 gave higher affinity in vitro, such substituents were a metabolic liability and caused shortfalls in vivo. Two approaches to prevent this metabolism, addition of a cyclic constraint and incorporation of trifluoromethyl groups, were examined. The former approach was ineffective because of metabolic hydroxylation on the constrained ring system, whereas the latter showed improvement in plasma pharmacokinetics in some cases. 相似文献
39.
EA Koller L Green JM Gertner M Bost SN Malozowski 《Canadian Metallurgical Quarterly》1998,83(7):2380-2383
A role for GH in the pathogenesis of diabetic retinopathy has long been postulated. Previous clinical studies, however, have been confounded by hyperglycemia. We have identified 2 cases of retinopathy associated with exogenous GH therapy in nondiabetic patients. Cases were identified through the MedWatch drug surveillance system of the U.S. Food and Drug Administration. Causality by concomitant medications was excluded by a search of the literature and the FDA data base. The first patient, an obese, 31-yr-old male with traumatic hypothalamic injury, presented with nonproliferative retinopathy and macular edema, resulting in decreased visual acuity (OD 20/40-1; OS count fingers), which required laser surgery. Human GH had been initiated at 0.009 mg/ kg.day, 14 months earlier, and titrated to 0.017 mg/kg.day. The second patient, a nonobese, 11-yr-old girl receiving GH for the management of short stature in Turner's Syndrome, presented with neovascularization. GH doses were 0.033 mg/kg.day for the first 17 months and 0.043 mg/ kg.day for the following 5 months. Cumulative laboratory and clinical observations suggest that GH and related peptides have a role in retinal pathology independent of the degree of glucose tolerance. 相似文献
40.
PURPOSE: To analyze the likelihood of perioperative transfusion using the data of the abstracted patient discharge records. MATERIAL AND METHODS: It was studied the data of the records of the pediatric patients in whom were done surgical procedures for 1996. The abstracted patient discharge records are codified according the ICD-9-CM codes. RESULTS: 1,166 pediatric patients were operated, of whom were transfused 25 (2.1%). The transfusion rate was higher in patients less than 3 years old, who were operated with three o more surgical procedures simultaneously, who were admitted newly after the admittance here studied, and patients operated of spine, dorsolumbar spine, pharynx, thorax and mediastinum, central nervous system, colon, vessels and hip. CONCLUSIONS: Given the variability of the transfusion rate, to know it will allow a better planning of the surgical transfusions, the policy of the hospital blood bank and to increase the information to patient about the risk of the elective surgery. 相似文献