In situ measurements of density fluctuations and compressibility in silica glass as a function of temperature and thermal history

In this paper, small-angle X-ray scattering measurements are used to determine the different compressibility contributions, as well as the isothermal compressibility, in thermal equilibrium in silica glasses having different thermal histories. Using two different methods of analysis, in the supercooled liquid and in the glassy state, we obtain respectively the temperature and fictive temperature dependences of the isotheraml compressibility. The values obtained in the glass and supercooled liquid states are very close to each other. They agree with previous determinations of the literature. The compressibility in the glass state slightly decreases with increasing fictive temperature. The relaxational part of the compressibility is also calculated and compared to previous determinations. We discussed the small differences between the different determinations

Characterization of the glass transition in vitreous silica by temperature scanning small-angle X-ray scattering

The temperature dependence of the x-ray scattering in the region below the first sharp diffraction peak was measured for silica glasses with low and high OH content (GE-124 and Corning 7980). Data were obtained upon scanning the temperature at 10, 40 and 80 K/min between 400 K and 1820 K. The measurements resolve, for the first time, the hysteresis between heating and cooling through the glass transition for silica glass, and the data have a better signal to noise ratio than previous light scattering and differential thermal analysis data. For the glass with the higher hydroxyl concentration the glass transition is broader and at a lower temperature. Fits of the data to the Adam-Gibbs-Fulcher equation provide updated kinetic parameters for this very strong glass. The temperature derivative of the observed X-ray scattering matches that of light scattering to within 14%.Comment: EurophysicsLetters, in pres

Cytotoxics compounded sterile preparation control by HPLC during a 16-month assessment in a French university hospital: importance of the mixing bags step

The Centralized Chemotherapy Reconstitution Unit (CCRU) of Paul Brousse Hospital Pharmacy Department assessed the reliability of its Cytotoxics Compounded Sterile Products (CCSP) preparation method in order to improve its CCSP quality assurance system. Five cytotoxic drugs — gemcitabine, 5-fluorouracil, docetaxel, paclitaxel, and oxaliplatin — were assayed by high performance liquid chromatography (HPLC) to determine CCSP concentration. During the observation period, 23,892 CCSP were prepared. Overall, 12,964 preparations contained one of the five analyzed drugs; 7382 (56.9%) out of 12,964 CCSP were analyzed by HPLC; 646 (8.8%) out of 7382 concentrations were outside ± 20% of the prescribed dose; 544 (84.2%) out of 646 were post-administration results and could not be verified. Out of 102 (15.8%) pre-administration results that were re-tested after re-shaking, 94 (92.2%) were found to be acceptable upon re-testing, and 8 (7.8%) were confirmed to be unacceptable and needed to be re-compounded. The 8.8% of tested CCSP were outside ± 20% of the prescribed dose, but extrapolating the results on re-tested CCSP, we can say that our CCSP preparation is reliable with an estimation of only 0.7% of 7382 CCSP analyzed, confirmed as being ± 20% outside the prescribed dose. Nevertheless, this ± 20% magnitude of error should be reduced. Based on pre-administration results, the primary cause of concentration errors appeared to be insufficient mixing of the finished product. Most CCSP dosages occurred after it had been administered, the organization should, therefore, be improved to include testing all CCSP prior to administration. Pharmaceutical companies should endeavor to manufacture compounded injectible drugs in a ‘ready to use’ form and provide vehicles in accurate volumes in order to improve compounding precision

Environmental stress affects the expression of a carotenoid-based sexual trait in male zebra finches.

Abiotic factors including thermal stress are suggested to exert constrains on sexual ornaments through trade-offs between sexual displays and physiological functions related to self-maintenance. Given the health properties of carotenoid pigments, carotenoid-based ornaments offer a relevant context in which to investigate the effect of environmental stress, such as ambient temperature, on the production and maintenance of secondary sexual traits and, also, to explore the proximate mechanisms shaping their expression. In this study, we exposed male zebra finches (Taeniopygia guttata) to environmental stress by exposing them to two temperature regimes (6 and 26 degrees C) over a 4 week period. Simultaneously, half of the males in each temperature group were supplemented with carotenoids, whereas the other half were not. The expression of a carotenoid-based sexual trait (bill colour) and the amount of circulating carotenoids were assessed before and at the end of the experiment. Carotenoid-supplemented males developed a redder bill, but the effect of supplementation was reduced under cold exposure. However, we found evidence that birds facing a cold stress were carotenoid limited, since supplemented males developed redder bills than the non-supplemented ones. Interestingly, while cold-exposed and non-supplemented males developed duller bills, they circulated a higher amount of carotenoids at the end of the experiment compared to the pre-experimental values. Together, these results suggest that ambient temperature might contribute to the modulation of the expression of carotenoid-based ornaments. Our findings suggest that carotenoids are a limiting resource under cold exposure and that they might be prioritized for self-maintenance at the expense of the ornament. The physiological functions related to self-maintenance that might have benefited from carotenoid saving are discussed