Fretting Fatigue in Alumina Tested under Oscillating Normal Load

The effect of an oscillating normal force (fretting Mode II) on the degradation mechanism in an alumina versus a WC-Co ball-on-flat contact is presented. A sinusoidal oscillation of the normal force at a fixed frequency and normal force amplitude was applied for different numbers of cycles. The evolution of the surface damage with an increasing number of cycles at a constant force amplitude is reported. In general, wear is taking place in the slip region on alumina balls and on WC-Co flats. The oscillating normal force generates fatigue cracks on the surface of the alumina balls, but not on the WC-Co flats. Fatigue crack initiation life under fretting Mode II test conditions is evaluated for alumina in a plot of maximum normal load versus number of fretting cycles.     

Electrochemical investigation of the codeposition of SiC and SiO2 particles with nickel

The use of electrochemical impedance spectroscopy (EIS) for the in situ control of the electrolytic codeposition of Ni/SiO₂ and Ni/SiC was investigated. An attempt was made to clarify why silica particles hardly codeposit in comparison to silicon carbide particles. It was found that the presence of SiO₂ and SiC particles influences the metal deposition process in different ways. SiC particles that are being embedded in the growing metal layer cause an apparent decrease in the electrode surface area, probably due to blocking off a part of the surface by partly engulfed particles. In the case of SiO₂ particles, which embed in the metal matrix to a very limited extent, no blocking was observed. It was found that the presence of particles in the solution causes an apparent increase in the electrode surface area, probably due to increased surface roughness.     

Effect of the electrodeposition conditions on the morphology,composition and physicomechanical properties of Co-Mo-P alloys

By means of electron microscopy, EDX analysis, and tribotesting, there is found a correlation between the composition, morphology, and properties of Co-Mo-P alloy coatings deposited at direct current from a citrate electrolyte containing ammonium hypophosphite in a current density range of 1–15 A/dm², at temperatures of 28 and 60°C, and pH of 4–6. It is shown that the electrolyte pH increase from 4 to 6 leads to a decrease in the phosphorus content and to an increase in the molybdenum concentration in the electrodeposits. A direct correlation between the microhardness and the wear resistance of electrodeposits and the phosphorus content in coatings is shown.     

Proteome profiling of bladder squamous cell carcinomas: identification of markers that define their degree of differentiation

One hundred fifty fresh bladder tumors were analyzed blindly by two-dimensional PAGE in combination with proteome identification techniques (microsequencing and mass spectrometry) and immunofluorescence of cryostat sections. Of these, six showed protein expression patterns corresponding to squamous cell carcinomas (SCCs). All tumors were already invasive at the time of presentation, and in most cases, the histopathological grade could not be determined with certainty. The more differentiated of the tumors included SCC 589-1, a lesion showing extensive keratinization, and 536-1, a pure SCC that resembled normal skin growing invasively into the muscle. Both tumors expressed keratins 5, 6, 10, 14, 16, 17, and 20, as well as the differentiation-associated proteins psoriasin, psoriasis-associated fatty acid-binding protein (PA-FABP), and galectin 7. SCC 589-1, however, exhibited higher levels of keratin 10, PA-FABP, and galectin 7 and, in addition, expressed keratins 13, 15, and 19, which were not detected in the pure SCC. Involucrin, glutathione S-transferase pi, stratifin (14-3-3 sigma), and the SCC antigen 1, on the other hand, were less abundant in SCC 589-1. In comparison, less-differentiated tumors did not express keratin 10 and were characterized by a decreased expression of keratin 14, psoriasin, PA-FABP, galectin 7, and stratifin (14-3-3 sigma). Indeed, two of these lesions (553-1 and 651-1) could be readily lined up in order of decreasing degree of differentiation based on the expression of these markers. The degree of differentiation of the other two SCCs could not be assessed with certainty because they may represent special cases (SCC 646-1, solid tumor; SCC 485-1, special differentiation pattern). All six SCCs externalized psoriasin to the urine, supporting the contention that this protein, alone or in combination with other polypeptides, may represent a useful marker for the early detection of these lesions.     

Synthesis of intermetallics for high temperature structural applications: (Mn5Si3)16H crystal structure

The Zr-Si system was chosen to study the potentiality of the (Mn₅Si₃)16H crystal structure for high temperature structural applications. A procedure was devised for the synthesis of intermetallics that have very high melting points. By hot isostatic pressing in a glass capsule, highly densified samples of Zr₅Si₃ were produced. Mechanical properties were measured. This compound is a good candidate for high temperature structural applications.     

Cloning, expression, and chromosome mapping of human galectin-7

The galectins are a family of beta-galactoside-binding proteins implicated in modulating cell-cell and cell-matrix interactions. Here we report the cloning and expression of a novel member of this family (galectin-7) that correspond to IEF (isoelectric focusing) 17 (12,700 Da; pI, 7.6) in the human keratinocyte protein data base, and that is strikingly down-regulated in SV40 transformed keratinocytes (K14). The cDNA was cloned from a lambda gt11 cDNA expression library using degenerated oligodeoxyribonucleotides back-translated from an IEF 17 peptide sequence. The protein encoded by the galectin-7 clone comigrated with IEF 17 as determined by two-dimensional (two-dimensional gel electrophoresis) analysis of proteins expressed by transiently transfected COS-1 cells, and bound lactose. Alignment of the amino acid sequences with other members of the family showed that the amino acids central to the beta-galactoside interaction are conserved. Galectin-7 was partially externalized to the medium by keratinocytes although it has no typical secretion signal peptide. Immunoblotting as well as immunofluorescence analysis of human tissues with a specific galectin-7 antibody revealed a narrow distribution of the protein which was found mainly in stratified squamous epithelium. The antigen localized to basal keratinocytes, although it was also found, albeit at lower levels, in the suprabasal layers where it concentrated to areas of cell to cell contact. Both, its cellular localization as well as its striking down-regulation in K14 keratinocytes imply a role in cell-cell and/or cell-matrix interactions necessary for normal growth control. The galectin-7 gene was mapped to chromosome 19.     

Alcohol and traumatic death in Jalisco

Percutaneous fine needle aspiration biopsy (FNAB) were performed in 22 cases of pancreatic lesions. FNAB was done with the help of ultrasonographic guidance in 14 cases and intraoperatively in 2 cases. In rest of the cases it was done without any radiological guidance. Diagnosis was confirmed either by histopathology or exploratory laparotomy by follow-up data in rest of the cases. There was no false positive or negative diagnosis. Nuclear crowding, nuclear enlargement and prominent nucleoli were the important cytological criteria for pancreatic adenocarcinoma. Cytology smears of the islet cell tumour show round to oval monomorphic cells with central to eccentric nuclei and fine reddish granulations in cytoplasm. There was no complication following aspiration. Thus FNAB of pancreas is a relatively safe, reliable and quick technique which can be performed under ultrasound guidance.     

Heterogeneous nuclear ribonucleoproteins H, H', and F are members of a ubiquitously expressed subfamily of related but distinct proteins encoded by genes mapping to different chromosomes

Molecular cDNA cloning, two-dimensional gel immunoblotting, and amino acid microsequencing identified three sequence-unique and distinct proteins that constitute a subfamily of ubiquitously expressed heterogeneous nuclear ribonucleoproteins corresponding to hnRNPs H, H', and F. These proteins share epitopes and sequence identity with two other proteins, isoelectric focusing sample spot numbers 2222 (37.6 kDa; pI 6.5) and 2326 (39.5 kDa; pI 6.6), indicating that the subfamily may contain additional members. The identity between hnRNPs H and H' is 96%, between H and F 78%, and between H' and F 75%, respectively. The three proteins contain three repeats, which we denote quasi-RRMs (qRRMs) since they have a remote similarity to the RNA recognition motif (RRM). The three qRRMs of hnRNP H, with a few additional NH2-terminal amino acids, were constructed by polymerase chain reaction amplification and used for ribohomopolymer binding studies. Each qRRM repeat bound poly(rG), while only the NH2-terminal qRRM bound poly(rC) and poly(rU). None of the repeats bound detectable amounts of poly(rA). The expression levels of hnRNPs H and F were differentially regulated in pairs of normal and transformed fibroblasts and keratinocytes. In normal human keratinocytes, the expression level of H was unaffected by treatment with several substances tested including two second messengers and seven cytokines. Likewise the expression level of F was independent of these substances, although it was strikingly down-regulated by long term treatment with 4 beta-phorbol 12-myristate 13-acetate, indicating that the protein kinase C signaling pathway regulates its expression. No effect of 4 beta-phorbol 12-myristate 13-acetate was observed on the expression of hnRNP H. The genes coding for hnRNPs H, H', and F were chromosome-mapped to 5q35.3 (HNRPH1), 6q25.3-q26, and/or Xq22 (HNRPH2) and 10q11.21-q11.22 (HNRPF), respectively.     

Fretting Laboratory Tests: Analysis of the Mechanical Response of Test Rigs

The current state of the art of the experimental approach to fretting is discussed. The mechanical response of fretting equipment is analysed to establish the limits of the reliable use of fretting rigs. The effect of stiffness and dynamic response of fretting test rigs are extensively discussed, and a simple one freedom-degree model is proposed to describe, in a first approach, the response of the tangential force measuring systems.