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31.
An experimental study of the effects produced by different parameters of the heat-quenching cycle permitted the optimization of the properties typical of these martensitic stainless steels: hardness and corrosion resistance. The results obtained demonstrate that the heating temperatures currently used in industrial quenching treatment of these steels should be modified. 相似文献
32.
R. Burlot R. Moncorgé H. Manaa G. Boulon Y. Guyot J. Garcia Solé D. Cochet-Muchy 《Optical Materials》1996,6(4):313-330
The polarized absorption and luminescence properties of Nd3+ doped isostructural LiNbO3, MgO:LiNbO3 and LiTaO3 nonlinear bulk single crystals are reported. Pump-probe experiments associated with the Judd-Ofelt approach are used to estimate two types of room temperature cross sections: polarized emission cross sections of the dominant 4F3/2 → 4I1//2 transition near 1085 and 1093 nm and polarized excited-state absorption cross sections in the same spectral domain and in the green spectral range corresponding to self frequency doubling. Self frequency-doubling results are also given in Nd:LiNbO3 and Nd:MgO:LiNbO3 versus sample temperature. 相似文献
33.
M Nimtz W Martin V Wray KD Kl?ppel J Augustin HS Conradt 《Canadian Metallurgical Quarterly》1993,213(1):39-56
The native structures of the Asn-linked oligosaccharides and the O-glycans at Ser126 of human erythropoietin expressed from recombinant BHK cells have been elucidated. Enzymatically released N-glycans were studied by methylation analyses, fast-atom-bombardment mass spectrometry as well as one- and two-dimensional 1H-NMR spectrometry at 600 MHz. Many (82.7%) were found to be tetraantennary N-acetyllactosamine-type (22.8% with one, 3.6% with two and 0.4% with three N-acetyllactosamine repeats) being tetrasialylated (41%), trisialylated (29.6%) and disialylated (12.2%). A few (9.7%; 4.1% 2,4-branched, 5.6%, 2,6-branched) of the chains were triantennary (5.4% trisialyl, 4.3% disialyl) and 4.6% were of the disialyl diantennary type. Almost all of the innermost GlcNAc residues were alpha 1-6 fucosylated and NeuAc was exclusively alpha 2-3 linked to Gal beta 1-4GlcNAc-R; 60% of the protein was found to be O-glycosylated at Ser126; structures were monosialylated (70%) or disialylated (30%) forms of the Gal beta 1-3GalNAc core type. Glycosylation patterns at individual Asn-Xaa-Thr/Ser sites were determined by analytical high-pH anion-exchange chromatography with pulsed amperometric detection. Only tetraantennary chains with 0-3 N-acetyllactosamine repeats were detected at Asn38 and Asn83, while almost all of the di- and triantennary oligosaccharides were attached to Asn24. Batch analysis of different preparations of recombinant erythropoietin revealed the high reproducibility of the production procedure. Structures containing terminal GalNAc-GlcNAc were detected in small amounts in a few batches. 相似文献
34.
A major concern of researchers using state data sets for population-based analyses and market share studies in the health care sector is the potential bias caused by 'border crossing'--patients receiving care out of state. By using the Health Care Financing Administration (HCFA) discharge abstract files for 1987 and 1988, we found that 'border crossing' is not a serious problem for the two large states we examined. Only 4.4% of New York patients and 2.15% of California patients received care out of state. At the county and zip code level, 'border crossing' is more frequent but tends to be concentrated in areas adjacent to other states. Even excluding all zips with more than 10% of patients crossing the 'border' results in a small loss of patients (2.2% for New York and 1.0% for California). 相似文献
35.
36.
TH Lim HS An T Hasegawa L McGrady KY Hasanoglu CR Wilson 《Canadian Metallurgical Quarterly》1995,20(23):2565-8; discussion 2569
STUDY DESIGN: A biomechanical study was performed to investigate a relation between the bone mineral density of the vertebral body and the number of loading cycles to induce fatigue loosening of an anterior vertebral screw. OBJECTIVES: The objective of this study was to investigate the potential usefulness of dual energy x-ray absorptiometry of measuring bone mineral density of the vertebral body in predicting the fatigue loosening of th anterior vertebral screw. SUMMARY OF BACKGROUND DATA: Loosening of the vertebral body screw is a well know failure in spinal instrumentation, and more commonly observed than pullout failure. The relation between bone mineral density and pullout strength of the screw has been investigated previously, but no studies are available on the fatigue loosening in anterior spinal fixation. METHODS: Bone mineral density was measured using dual energy x-ray absorptiometry and the screw loosening was produce by a cyclic loading in the cephalad-caudal direction. Screw loosening was defined as 1 mm displacement of the screw relative to bone, and the number of loading cycles to induce the screw loosening was obtained and statistically correlated with bone mineral density. RESULTS: There was a positive correlation between the number of loading cycles to induce screw loosening and bone mineral density (R = 0.8, P < 0.01). The average number of loading cycles to induce screw loosening was significantly less for specimens with bone mineral density < 0.45 g/cm2 compared to those with bone mineral density > or = g/cm2. CONCLUSIONS: These findings suggest that bone mineral density may be a good predictor of anterior vertebral screw loosening. Bone mineral density < 0.45 g/cm2 may be critical value of loosening of the anterior vertebral body screw. However, further biomechanical and clinical studies are required before using threshold value clinically. 相似文献
37.
F Devlieghere B De Meulenaer P Sekitoleko AA Estrella Garcia A Huyghebaert 《Canadian Metallurgical Quarterly》1997,14(6-7):671-683
In this study several types of bottle materials (glass, PET (polyethylene terephthalate), PC (polycarbonate), HDPE (high density polyethylene), PP (polypropylene) and PVC (polyvinyl chloride)) were evaluated in order to be used as food refillables, comparing the residual chemical contamination after classical caustic washing. Bottles were contaminated with model chemicals (chloroxylenol and d-limonene) and caustic washed with varied process parameters using a simulated laboratory-scale washing procedure. After washing, the chemical-contaminated bottles were filled with water and stored for 28 days at 37 degrees C. The concentrations of the model chemicals in the water after storage were taken as a measure of chemical contamination. The influence of the cleaning parameters (temperature, caustic and commercial additive concentration) was studied using response surface methodology. Washing temperature showed a significant influence on the removal of absorbed chemicals from surfaces compared with the effect of the caustic and especially the additive concentration. Optimization of caustic cleaning for the cleaning process in question led to better cleaning effectiveness, although none of the different washing conditions were able to remove all absorbed chemicals out of the polymeric resins. Commercially available plastic refillables (PET and PC) showed the best chemical rinsability. Glass bottles, however, had in every case the best rinsing characteristics. 相似文献
38.
Lean body mass (LBM), total body bone mineral mass (BMC), total body bone areal density (BMD), and body fat mass (FM) were measured in rats by dual photon absorptiometry (DXA), using two different instruments. The coefficients of variation for repeated measurements of LBM and FM were about 0.4 and 2.5%, respectively, over an animal body weight range of 150 to 600 g. For BMC and BMD, the coefficients of variation were less than 2%. The correlation coefficients for LBM, FM, BMC, and BMD measured on the two densitometers were all greater than 0.94. The slope of the regression line relating LBM measured by DXA and LBM measured by carcass analysis was 0.999, and the correlation coefficient was 0.99. For FM the slope was 1.05, and the correlation coefficient was 0.98. BMC measures by DXA were falsely low in small animals. For larger animals, the correlation between BMC and ash weight was 0.93, but the slope of the regression line was 0.78. DXA measures of LBM and FM were accurate and reproducible for rats weighing between 150 and 600 g. There was a size-dependent error in BMC, which will be significant in longitudinal measurements of bone mass. 相似文献
39.
The crystallization of Pd40Ni40P20 glass, produced by melt-spinning in air, has been studied by optical metallography. Crystallization is predominantly from the surface and is more prevalent on the wheel-side. The non-uniformity is attributed to variation in quench rate during production. A three-stage anneal permits crystals which have nucleated at the surface to be identified and their size distribution to be analysed. The surface nucleation is heterogeneous and appears to be hindered by mild oxidation. The annealing atmosphere markedly affects the surface crystallization behaviour, as does removal of the original ribbon surface. When nucleation is sparse, partial crystallization causes the development of noticeable relief on the sample surfaces. 相似文献
40.