Intermetallic compounds in the M–Cu–Sn systems with M = Eu,Sr, Ba

Several samples were prepared in the title systems, starting from the elements sealed under argon in Ta crucibles, melting in an induction fornace and annealing at 823 K. Six ternary phases were found: EuCu₂Sn₂, a = 11.100 (3), b = 4.307 (1), c = 4.824 (1) Å, β = 108.88 (1)°, and SrCu₂Sn₂, a = 11.197 (4), b = 4.322 (2), c = 4.859 (1) Å, β = 108.43 (1)°, C2/m, CaCu₂Sn₂-type, closely related to the BaAl₄ structure; Sr₃Cu₈Sn₄, a = 9.3280 (2), c = 7.8826 (4) Å, P6₃mc, Nd₃Co₈Sn₄-type, ordered variant of the BaLi₄-type; SrCu₄Sn₂, a = 8.176 (1), c = 7.799 (1) Å, I4/mcm, CaNi₄Sn₂-type; SrCu₉Sn₄, a = 8.663 (1), c = 12.457 (2) Å, and BaCu₉Sn₄, a = 8.717 (1), c = 12.545 (2) Å, I4/mcm, LaFe₉Si₄-type, ordered variant of the NaZn₁₃ structure. The structure of the first compound was refined by the Rietveld method, while single crystal data were used for the others. Some remarks are given on the crystal chemistry of the encountered and related structure types.     

A PC-interfaced, compact laser-diode feedback interferometer fordisplacement measurements

We describe a laser-diode feedback interferometer for displacement measurements with directional discrimination and resolution better than 10^-6 m. This new, compact instrument consists of a small optical head and a signal processing board, which is interfaced to a personal computer. The prototype developed has a dynamic range of 2 m and an accuracy of about 5 μm/m, using a corner cube as a remote reflector. Thanks to PC interfacing, the displacement is directly available in metric units and errors due to temperature fluctuations can be corrected with software signal processing     

Isolation, characterization and differentiation of mesenchymal stem cells from amniotic fluid, umbilical cord blood and Wharton's jelly in the horse

Mesenchymal stem cells (MSCs) have been derived from multiple sources of the horse including umbilical cord blood (UCB) and amnion. This work aimed to identify and characterize stem cells from equine amniotic fluid (AF), CB and Wharton's Jelly (WJ). Samples were obtained from 13 mares at labour. AF and CB cells were isolated by centrifugation, while WJ was prepared by incubating with an enzymatic solution for 2 h. All cell lines were cultured in DMEM/TCM199 plus fetal bovine serum. Fibroblast-like cells were observed in 7/10 (70%) AF, 6/8 (75%) CB and 8/12 (66.7%) WJ samples. Statistically significant differences were found between cell-doubling times (DTs): cells isolated from WJ expanded more rapidly (2.0±0.6 days) than those isolated from CB (2.6±1.3 days) and AF (2.3±1.0 days) (P<0.05). Positive von Kossa and Alizarin Red S staining confirmed osteogenesis. Alcian Blue staining of matrix glycosaminoglycans illustrated chondrogenesis and positive Oil Red O lipid droplets staining suggested adipogenesis. All cell lines isolated were positive for CD90, CD44, CD105; and negative for CD34, CD14 and CD45. These findings suggest that equine MSCs from AF, UCB and WJ appeared to be a readily obtainable and highly proliferative cell lines from a uninvasive source that may represent a good model system for stem cell biology and cellular therapy applications in horses. However, to assess their use as an allogenic cell source, further studies are needed for evaluating the expression of markers related to cell immunogenicity.     

The high temperature corrosion resistance of α-phase bronzes

The oxidation of Cu-Sn alloys containing up to 13 wt% Sn in oxygen (1 atm) has been studied in the temperature range 550 °C to 800 °C at 50 °C intervals; the investigation involved the study of the kinetics and of the morphology and structure of the scales by appropriate physical methods, with the aim of correlating the two aspects of the oxidation behaviour. The oxidation rate of a 3 wt% Sn alloy is lower than for pure Cu at 550 and 600 °C, but higher above 600°C. The effect of the tin addition is related to the interplay of many different factors affecting the reaction rate, the overall result depending on temperature. The rate of oxidation of the more concentrated alloys, however, is always lower than that of pure Cu. This result is attributed to the formation of an SnO₂ layer at the base of the scale which, although thin and usually discontinous, slows down the outward diffusion of copper. The highest tin concentration allowed by its high temperature solubility in copper is not sufficient to produce a continous thick healing layer of SnO₂ at the alloy surface, but nevertheless it produces a pronounced decrease of the oxidation rate.     

Somatic deletion mapping on chromosome 10 and sequence analysis of PTEN/MMAC1 point to the 10q25-26 region as the primary target in low-grade and high-grade gliomas

The 10q25-26 region between the dinucleotide markers D10S587 and D10S216 is deleted in glioblastomas and, as we have recently shown, in low-grade oligodendrogliomas. We further refined somatic mapping on 10q23-tel and simultaneously assessed the role of the candidate tumor suppressor gene PTEN/MMAC1 in glial neoplasms by sequence analysis of eight low-grade and 24 high-grade gliomas. These tumors were selected for partial or complete loss of chromosome 10 based on deletion mapping with increased microsatellite marker density at 10q23-tel. Three out of eight (38%) low-grade and 3/24 (13%) high-grade gliomas exclusively target 10q25-26. We did not find a tumor only targeting 10q23.3, and most tumors (23/32, 72%) showed large deletions on 10q including both regions. The sequence analysis of PTEN/MMAC1 revealed nucleotide alterations in 1/8 (12.5%) low-grade gliomas in a tumor with LOH at l0q21-qtel and in 5/21 (24%) high-grade gliomas displaying LOH that always included 10q23-26. Our refined mapping data point to the 10q25-26 region as the primary target on 10q, an area that also harbors the DMBT1 candidate tumor suppressor gene. The fact that we find hemizygous deletions at 10q25-qtel in low-grade astrocytomas and oligodendrogliomas - two histologically distinct entities of gliomas - suggests the existence of a putative suppressor gene involved early in glial tumorigenesis.