Investigation of the Mechanical Properties of Oxide Scales on Nickel and TiAl

In this paper, a modified four-point bending test is described, which allows a quantitative determination of the mechanical properties of oxide scales on metallic substrates at temperatures from ambient to 900°C. Scale failure is detected by acoustic emission. By combining deformation data with the physical defect-structure values for the scales, fracture toughnesses have been evaluated for the cases of through-scale cracking and delamination/spalling. The test was applied to NiO scales on pure nickel and to the oxide scales on an intermetallic TiAl alloy at room temperature and 900°C, respectively. The fracture-toughness values determined in these investigations correspond to the order of magnitude expected from the rare literature data. The test itself can also be applied to a variety of brittle coatings on more-or-less ductile substrates.     

Intramedullary pressure reduction in the femur shaft in total hip endoprosthesis. Effect on the rate of thrombosis]

PROBLEM: Factors in seminal plasma stimulate an intense but transient inflammatory response in the murine endometrium at mating. The aim of our current studies is to delineate the cytokine-leukocyte interactions comprising this response and to elucidate the significance of these events in changes in the maternal immune system and as determinants of pregnancy outcome. METHOD: We have reviewed our recent findings. RESULTS: Transforming growth factor (TGF)-beta1 has been identified as the inflammation-inducing moiety in seminal plasma. Seminal TGFbeta1 initiates endometrial leukocyte infiltration by up-regulating epithelial cell expression of granulocyte-macrophage colony-stimulating factor. Other cytokines and chemokines including regulated and normal T-cell expressed and secreted (RANTES), macrophage inflammatory protein (MIP)-1alpha, MIP-1beta, and monocyte chemotactic protein-1 are also implicated as mediators of macrophage and granulocyte recruitment and activation. One consequence of this inflammatory response is the induction of a transient state of hyporesponsiveness to paternal major histocompatibility class I antigens. CONCLUSION: Our studies suggest that semen may play a critical role in providing the antigenic and environmental signals necessary to initiate an appropriate maternal immune response to the conceptus during pregnancy.     

The effect of tolerance to noninherited maternal HLA antigens on the survival of renal transplants from sibling donors

BACKGROUND: During pregnancy and nursing, a baby's developing immune system is intimately exposed to the mother's antigens. To determine whether this exposure is of clinical benefit to patients who later receive an allograft as an adult, we analyzed the outcome of primary renal transplantations from sibling donors. METHODS: We retrospectively studied graft survival and rejection episodes in 205 patients who had received renal transplants at nine centers between 1966 and 1996 from sibling donors bearing maternal or paternal HLA antigens not inherited by the recipient. The sibling donors were categorized by analysis of family HLA-typing data. RESULTS: In the multicenter analysis, graft survival was higher at 5 years and at 10 years after transplantation in recipients of kidneys from siblings expressing maternal HLA antigens not inherited by the recipient than in recipients of kidneys from siblings expressing paternal HLA antigens not inherited by the recipient (86 percent vs. 67 percent at 5 years and 77 percent vs. 49 percent at 10 years, P=0.006 for both). Paradoxically, there was a higher incidence of early rejection in the former group, suggesting that fetal and neonatal exposure to maternal antigens results in immunologic priming. Pretransplantation transfusions of donor blood reduced the incidence of acute rejection while preserving the beneficial effect of tolerance to noninherited maternal antigens on graft survival. Since 1986, new immunosuppressive drugs have lessened the short-term, but not the long-term, survival advantage of grafts expressing maternal HLA antigens not inherited by the recipient. CONCLUSIONS: In the transplantation of a kidney from a sibling donor who is mismatched with the recipient for one HLA haplotype, graft survival is higher when the donor has maternal HLA antigens not inherited by the recipient than when the donor has paternal HLA antigens not inherited by the recipient.     

Donor-specific anti-human leukocyte antigen class I antibodies after implantation of cardiac valve allografts

The allospecific humoral immune response was examined in 31 patients in the first year after implantation of cryopreserved human cardiac valves. We determined the percentage antibodies against human leucocyte antigens (HLA) class I in a complement-dependent microlymphocytotoxicity test against a panel of 50 selected donors carrying most of the defined HLA-A and HLA-B specificities (panel-reactive antibodies). In blood samples taken immediately before implantation, no antibodies could be detected. Thereafter, antibodies were present in 23 of 31 (74%) patients (median panel-reactive antibodies: 57%, range 9% to 91%). In 21 patients the HLA-type of the valve donor was available. In four patients no blood samples taken after 4 weeks were available. In 14 of 17 patients (82%) with a follow-up of more than 1 month antibodies were present, and in 12 of these 14 (86%) antibodies were specifically directed against HLA class I of the donor. In conclusion, the formation of donor-specific antibodies is frequently observed after human cardiac valve replacement. It could be one of the factors leading to valve destruction and dysfunction.     

纳米操纵机器人及其自动化设计

在纳米技术和纳米材料领域,纳米操纵机器人已经成为一种用于分析和制作原型纳米器件的使能技术.这类纳米操纵机器人拾放操作灵活,可将单个纳米器件集成到现有的微器件中来提高微器件的总体性能和灵敏度.如今这种被称作微纳米集成装配的自动化装置不再局限于实验室使用,还需要应用于工业领域.本文综述了纳米微操作机器人的产生、集成装配和自动化等方面的基础技术,同时探讨了不同种类原子力显微镜超级探针的装配方案.     

A local feature method for the detection of flaws in automated X-ray inspection of castings

A local feature method is described which is applicable to automatic X-ray inspection of cast aluminium car parts. The method is applied as follows: A local feature operator reduces the incoming grey-level image to a feature image yielding high feature values for the flaws (shrink-holes) and low values for most of the regular regions of the test piece. The final good/no-good decision is based on flexible matching of the feature image with the feature image of a good reference part. Results are given showing the performance of the method when applied to X-ray radiographs of small aluminium castings.     

Multifunctional FeCo/TiN Multilayer Thin Films with Combined Magnetic and Protective Properties

Coatings with thicknesses ranging from a few nanometer up to several micrometer produced by physical vapor deposition (PVD) processes have been established in engineering technologies since the early 1980s. In particular, magnetron sputtered wear resistance coatings are industrially established and capable to enhance tool lifetimes significantly. However, in cases where optical inspection of a coating in use is not possible, an intrinsic sensor function of the film would be beneficial. Therefore, the development of wear resistant coatings with an integrated sensor functionality based on the insertion of a magnetoelastic ferromagnetic phase is suggested. In combination with appropriate read‐out electronics such a film system would be ready for online monitoring of the coatings' actual state (e.g., strain, temperature, volume loss). This paper focuses on the development of wear resistance coatings which simultaneously supply beneficial mechanical properties as well as ferromagnetic properties optimized for online non‐contact read‐out applications. Multilayer coatings obtained through alternate stacking of magnetron sputtered TiN and FeCo layers with a nominal total thickness of 1000 nm were produced as a model system meeting the above conditions. The bilayer period was varied down to 2.6 nm while the individual layer thickness ratio t_TiN/t_FeCo was determined by the deposition rates and maintained constant at a value of about 3/1. The films were vacuum annealed ex situ in a static magnetic field subsequent to the deposition. The constitution of the as‐deposited and annealed coatings as well as their mechanical (nanohardness, Young's modulus) and magnetic properties (magnetization hysteresis, frequency‐dependent permeability) are described. Finally, the suitability of the coatings for the use in remote‐interrogable wear sensor applications is briefly discussed.     

Zinc and flunitrazepam modulation of GABA-mediated currents in rat suprachiasmatic neurons

We know that upper body obesity is associated with metabolic complications, but we don't know how regional body fat distribution influences postprandial lipemia in obese adults. Thus, this study explored the respective effects of android or gynoid types of obesity and fasting triglyceridemia on postprandial lipid metabolism and especially triglyceride-rich lipoproteins. Twenty-four obese and 6 lean normotriglyceridemic women (control), age 24-57 yr, were enrolled. Among obese women with an android phenotype, 9 exhibited normal plasma triglyceride levels (mean: 1.38 mmol/L) (NTAO), and 7 displayed a frank hypertriglyceridemia (mean: 2.40 mmol/L) (HTAO). The 8 patients with a gynoid phenotype had normal triglyceride levels (mean: 1.00 mmol/L) (GO). All were given a mixed test meal providing 40 g triglycerides. Serum and incremental chylomicron triglycerides 0-7 h areas under the curve (AUCs) as well as triglyceride levels in apoB-48-containing triglyceride-rich lipoprotein (TRLs) or chylomicrons were significantly higher in HTAOs and NTAOs than in GOs and controls postprandially. The size of chylomicron particles was bigger in controls and GOs than in HTAOs and NTAOs postprandially. Android obese subjects showed abnormally elevated fasting apoB-48 and apoB-100 triglyceride-rich lipoprotein (TRL) levels. Most abnormalities that were found correlated to plasma levels of insulin and apoC-III. In conclusion, an abnormal postprandial lipid pattern is a trait of abdominal obesity even without fasting hypertriglyceridemia.     

Centering Single Cells in Microgels via Delayed Crosslinking Supports Long‐Term 3D Culture by Preventing Cell Escape

Single‐cell‐laden microgels support physiological 3D culture conditions while enabling straightforward handling and high‐resolution readouts of individual cells. However, their widespread adoption for long‐term cultures is limited by cell escape. In this work, it is demonstrated that cell escape is predisposed to off‐center encapsulated cells. High‐speed microscopy reveals that cells are positioned at the microgel precursor droplets' oil/water interface within milliseconds after droplet formation. In conventional microencapsulation strategies, the droplets are typically gelled immediately after emulsification, which traps cells in this off‐center position. By delaying crosslinking, driving cells toward the centers of microgels is succeeded. The centering of cells in enzymatically crosslinked microgels prevents their escape during at least 28 d. It thereby uniquely enables the long‐term culture of individual cells within <5‐µm‐thick 3D uniform hydrogel coatings. Single cell analysis of mesenchymal stem cells in enzymatically crosslinked microgels reveals unprecedented high cell viability (>90%), maintained metabolic activity (>70%), and multilineage differentiation capacity (>60%) over a period of 28 d. The facile nature of this microfluidic cell‐centering method enables its straightforward integration into many microencapsulation strategies and significantly enhances control, reproducibility, and reliability of 3D single cell cultures.