Thermal and viscoelastic behaviour of copolymers of propene and 1-hexene

Summary The thermal and viscoelastic behaviour of several copolymers of propene and 1-hexene have been studied in a wide range of compositions. The samples were prepared with a Ziegler-Natta catalyst with both internal and external donors. A significant amount of crystallinity has been found for the sample with a comonomer content as high as 19 mol %. The dynamic mechanical results show a considerable decrease of the storage modulus in the copolymers in relation to that of iPP. A single relaxation, corresponding to the glass transition, has been found in all the samples. Only the copolymer with the highest hexene content seems to display the beginning of another relaxation at low temperature.     

Genomic alterations in fallopian tube carcinoma: comparison to serous uterine and ovarian carcinomas reveals similarity suggesting likeness in molecular pathogenesis

Serous carcinomas of the fallopian tube, uterus, and ovary resemble each other both histologically and in clinical behavior. Comparative genomic hybridization was performed on 20 primary fallopian tube carcinoma specimens to find regions of the genome involved in tubal carcinogenesis and to compare the genomic alterations with those previously detected in serous ovarian and uterine carcinomas. The most frequent changes detected in fallopian tube carcinoma were gains at 3q (70%) and 8q (75%), with high-level amplifications in several cases. Other common gains occurred at 1q, 5p, 7q, 12p, and 20q. The most frequent losses were found at 18q, 8p, 4q, and 5q. The frequency and the pattern of chromosomal changes detected in tubal carcinoma were strikingly similar to those observed in serous ovarian and uterine carcinomas, suggesting common molecular pathogenesis.     

Delayed elastic recovery of hardness indentations in polyethylene

The depth of Vickers microindentations in high density, low density and linear low density polyethylenes has been studied by two wave interferometry. The evolution of the delayed depth recovery is explained in terms of the Burgers model of viscoelastic behaviour and the numerical parameters associated with the model are related to the crystallinity, elastic modulus and yield stress of the polyethylenes studied.     

Size effect tests of torsional failure of plain and reinforced concrete beams

The current design code formulae for the torsional failure of plain or longitudinally reinforced beams exhibit no size effect, i.e. the failure of geometrically similar beams of different sizes is supposed to occur at the same nominal stress. Experiments on reduced-scale beams were carried out, and the results confirm that there is a significant size effect, such that the nominal stress at failure decreases as the beam size increases. This is found for both plain and longitudinally reinforced beams. The results are consistent with the recently proposed Bažant's size-effect law. However, the scatter of the results and the scope, and range limitations prevent it from being concluded that the applicability of this law is proven.     

TP53-Induced Glycolysis and Apoptosis Regulator (TIGAR) Is Upregulated in Lymphocytes Stimulated with Concanavalin A

The glycolytic modulator TP53-Inducible Glycolysis and Apoptosis Regulator (TIGAR) is overexpressed in several types of cancer and has a role in metabolic rewiring during tumor development. However, little is known about the role of this enzyme in proliferative tissues under physiological conditions. In the current work, we analysed the role of TIGAR in primary human lymphocytes stimulated with the mitotic agent Concanavalin A (ConA). We found that TIGAR expression was induced in stimulated lymphocytes through the PI3K/AKT pathway, since Akti-1/2 and LY294002 inhibitors prevented the upregulation of TIGAR in response to ConA. In addition, suppression of TIGAR expression by siRNA decreased the levels of the proliferative marker PCNA and increased cellular ROS levels. In this model, TIGAR was found to support the activity of glucose 6-phosphate dehydrogenase (G6PDH), the first enzyme of the pentose phosphate pathway (PPP), since the inhibition of TIGAR reduced G6PDH activity and increased autophagy. In conclusion, we demonstrate here that TIGAR is upregulated in stimulated human lymphocytes through the PI3K/AKT signaling pathway, which contributes to the redirection of the carbon flux to the PPP.     

Relationship between collagen characteristics,lipid content and raw and cooked texture of meat from young bulls of fifteen European breeds

Variations in texture were determined for 10 day aged raw and cooked Longissimus thoracis (LT) muscle from 436 bulls of 15 European cattle breeds slaughtered at an age of 13–16 months. Variations in texture were related to differences in pH 24 h post-mortem, sarcomere length, collagen characteristics and lipid content. The shear force of cooked meat samples varied from 43.8 to 67.4 N/cm². Simmental, Highland and Marchigiana cattle had the highest shear force values and Avileña-Negra Ibérica, Charolais, Casina and Pirenaica cattle had the lowest values. Cooked meat toughness showed a weak negative correlation to lipid content (P < 0.001) but no correlation to collagen characteristics. Raw meat texture measured by compression correlated positively (P < 0.001) with total and insoluble collagen. In conclusion, collagen characteristics showed correlation to raw meat texture but not to cooked meat toughness of LT muscle in European young bulls.     

Crosslinking of trimellitimide glycidyl ester derivatives

The cure reaction of diglycidyl trimellitimide esters with 4‐dimethylaminopyridine, diaminodiphenylmethane, and dicyandiamide as hardener was studied by differential scanning calorimetry (DSC). Isoconversional kinetic analysis was applied to nonisothermal DSC data and the dependences of activation energies on conversion degrees were obtained. Differences in the shape of these plots were found in accordance to the different kinetic schemes of the curing agents. The thermal properties of the final products evaluated by thermogravimetry do not show noteworthy differences. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 537–542, 1999