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1.
OBJECTIVE: The initially well-fixed implants of total hip replacement (THR) are in the long-term subject to aseptic loosening. Many cytokines can contribute to osteolysis due to osteoclast recruitment and/or activation. However, in this respect tumor necrosis factor-alpha (TNF-alpha) plays a pivotal role, because it upregulates interleukin-1 and 6 and granulocyte-macrophage colony stimulating factor. The aim of this study was to assess the eventual presence, cellular localization and extent of expression of TNF-alpha in the synovial-like membrane at the implant or at the cement to bone interface compared to control synovial membrane. METHODS: Twenty samples from the synovial-like membrane of the periprosthetic tissues were compared to control samples. TNF-alpha containing cells were visualized using an avidin-biotin-peroxidase complex (ABC) method and analyzed by light microscopy, double labelling and image analysis. RESULTS: TNF-alpha was found in the periprosthetic tissues in fibroblasts and vascular endothelial cells, but mainly in the macrophages was it found to coincide with areas containing implant-derived debris. TNF-alpha containing cells were more numerous in the synovial-like membrane in the interface tissue from the proximal stem area (2816 +/- 318 cells) than in the control synovial membrane (565 +/- 93 cells, p < 0.01). Interestingly, similarly high TNF-alpha expression (3452 +/- 582 cells) was also seen in the synovial-like membrane of the pseudocapsule. CONCLUSION: These findings suggest that the foreign body-type host reaction caused by THR is characterized by the high expression of TNF-alpha. Because such expression occurred in the interface tissue between the implant and surrounding bone, TNF-alpha, due to its pivotal direct and indirect role in the activation and recruitment of osteoclasts, may contribute to periprosthetic osteolysis and to the loosening of THR.  相似文献   
2.
A semi-empirical gas-liquid equilibrium model for the absorption of CO2 in aqueous 3M AMP (2-amino-2-methyl-1-propanol) is presented. It applies to high CO2 loadings (y > 0.5) in the temperature range between 20 and 50 °C, and is based on experimental solubility and pH determinations. For a given amine concentration, it yields the equilibrium partial pressure of CO2 as a function of only two variables: the CO2 loading and temperature. The model correlates the expressions for the chemical equilibria involved as follows: p = m y × 10x, where p is the equilibrium partial pressure, x = logK - pH, m is the amine molarity, y the CO2 loading, and K is a parameter involving Henry's law constant, H, and the first dissociation constant, K1, of carbonic acid. pH is found to depend on both temperature and CO2 loading while logK depends only on the CO2 loadIng. Correlations for pH and logK are presented. The model fits own data for 3M AMP very well as well as the equilibrium data found in recent literature.  相似文献   
3.
Conclusion It is expected that the research in high-temperature alloy development will reach a critical mass in about five years. This will not only raise the materials science of magnesium to a higher level but will also increase the confidence of the industry in magnesium as a structural performance material. Currently, applications are being actively pursued in United States Council for Automotive Research power train programs and European Council for Automotive R&D engine block programs to develop the technology for elevated-temperature magnesium. More research is still needed in this interesting materials field.  相似文献   
4.
In distributed database systems, tables are frequently fragmented and replicated over a number of sites in order to reduce network communication costs. How to fragment, when to replicate and how to allocate the fragments to the sites are challenging problems that has previously been solved either by static fragmentation, replication and allocation, or based on a priori query analysis. Many emerging applications of distributed database systems generate very dynamic workloads with frequent changes in access patterns from different sites. In such contexts, continuous refragmentation and reallocation can significantly improve performance. In this paper we present DYFRAM, a decentralized approach for dynamic table fragmentation and allocation in distributed database systems based on observation of the access patterns of sites to tables. The approach performs fragmentation, replication, and reallocation based on recent access history, aiming at maximizing the number of local accesses compared to accesses from remote sites. We show through simulations and experiments on the DASCOSA distributed database system that the approach significantly reduces communication costs for typical access patterns, thus demonstrating the feasibility of our approach.  相似文献   
5.
Five-year changes in episodic and semantic memory were examined in a sample of 829 participants (35-80 years). A cohort-matched sample (N=967) was assessed to control for practice effects. For episodic memory, cross-sectional analyses indicated gradual age-related decrements, whereas the longitudinal data revealed no decrements before age 60, even when practice effects were adjusted for. Longitudinally, semantic memory showed minor increments until age 55, with smaller decrements in old age as compared with episodic memory. Cohort differences in educational attainment appear to account for the discrepancies between cross-sectional and longitudinal data. Collectively, the results show that age trajectories for episodic and semantic memory differ and underscore the need to control for cohort and retest effects in cross-sectional and longitudinal studies, respectively. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
6.
Bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) from coal tar pitch polluted sediments was predicted by (1) a generic approach based on organic carbon-water partitioning and Gibbs linear free energy relationship (between K(OW) and K(OC)), and (2) measurements of freely dissolved concentrations of PAHs in the sediment pore water, using passive samplers and solid phase extraction. Results from these predictions were compared with those from in vivo bioaccumulation experiments using Nereis diversicolor (Polychaeta), Hinia reticulata (Gastropoda), and Nuculoma tenuis (Bivalvia). Measured sediment/water partition coefficients were higher than predicted by the generic approach. Furthermore, predicted biota-to-sediment accumulation factors (BSAFs) derived from measured pore water concentrations were more in agreement with the bioaccumulation observed for two of the three species. Discrepancies associated with the third species (N. tenuis) were likely a result of particles remaining in the intestine (as shown by microscopic evaluation). These results indicate the importance of conducting site-specific evaluations of pore water concentrations and/or bioaccumulation studies by direct measurements to accurately provide a basis for risk assessment and remediation plans. The importance of knowledge regarding specific characteristics of model organisms is emphasized.  相似文献   
7.
Reducing sugars and free amino acids were analysed in slices from three potato cultivars before and after blanching (0-3 min). The potato crisps were deep fried at 185 °C for different times (3-8.5 min), and analysed for the concentration of acrylamide (AA) and moisture. Potato cultivar and the temperature during processing were important parameters for AA formation in potato crisps. The amount increased with an increase in the processing time. Blanching before deep-frying reduced the concentration of free asparagine and reducing sugar in the raw material. We found no effect of blanching as pretreatment on the concentration of AA in the potato crisps. Any relationship was not detected between the levels of asparagine in the different cultivars, before and after blanching, and the formation of AA in the crisp products. However, it was shown that the content of reducing sugars determined the level of AA after frying.  相似文献   
8.
An investigation of the shape of the lactation curve and the mastitis incidence was conducted to identify whether management interventions of the lactation curve constitute a potential for reducing incidence of mastitis at herd level. Lactation curves were estimated to describe the variation of daily milk yield during the 305-d lactation period in Norwegian Red cows. Associations between mastitis incidence at herd level and lactation curve characteristics such as production level at onset of lactation, magnitude and time of peak milk yield, and increase and decrease of milk yield rates were studied. Data from 250,303 lactations occurring during 2005 and 2006 from 14,766 herds were obtained from the Norwegian Dairy Herd Recording System. Besides veterinary treatments, the records included information on monthly test-day milk yields. The shapes of the lactation curves at herd level were parameterized using a modified Wilmink model in two separate mixed model analyses. In the first analysis a subset of lactations with no records of veterinary treatments was used. Lactation curves from herds with high (>0·31 cases/305-d lactation) and low (<0·07 cases/305-d lactation) herd mastitis incidence rate were parameterized and compared for three separate strata of parity. The result showed that high herd mastitis incidence rate was associated with a low intercept (P<0·05), a steep slope before peak milk yield (P<0·01) and a rapid decline after peak milk yield (P<0·01). In the second analysis a subset of high-yielding lactations with veterinary treatments of mastitis only and lactations with no records of veterinary treatment were compared. This was done to investigate whether the findings at herd level were also reflected at cow level. These results showed that lactation curves from lactations with mastitis cases were associated with a steep slope before peak milk yield (P<0·05) in second and later parities and a rapid decline after peak milk yield (P<0·01) in all three parity groups.  相似文献   
9.
During the past several years, and particularly since the Clean Air Mercury Rule (CAMR) was promulgated in June of 2005, the electric utility industry, product vendors, and the research community have been working diligently to develop and test Hg control strategies for a variety of coal types and plant configurations. Some of these strategies include sorbent injection and chemical additives designed to increase mercury capture efficiency in particulate control devices. These strategies have the potential to impact the fate of other inorganic hazardous air pollutants (HAPs), which typically include As, Be, Cd, Cr, Co, Mn, Ni, Pb, Se, and Sb. To evaluate this impact, flue gas samples using EPA Method 29, along with representative coal and ash samples, were collected during recent pilot-scale and field test projects that were evaluating Hg control technologies. These test programs included a range of fuel types with varying trace element concentrations, along with different combustion systems and particulate control devices. The results show that the majority of the trace element HAPs are associated with the particulate matter in the flue gas, except for Se. However, for five of the six projects, Se partitioning was shifted to the particulate phase and total emissions reduced when Hg control technologies were applied.  相似文献   
10.
The use of the personal computer and the wide availability of powerful spreadsheet programs has given the motor designer a very powerful but simple-to-use tool. The use of the Symphony spreadsheet program, presently used to design pancake-type and linear induction motors, is described. As the original design process involved the development of a Fortran program to obtain similar design capabilities, a direct comparison between the development time, using a high-level language, and a spreadsheet program is made. In addition, it is shown how the Fortran program results can be incorporated into the spreadsheet programs to use the graphics capability and documentation features. This topic will be of interest to motor designers and educators.  相似文献   
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