Effect of free water removal from early-age hydrated cement pastes on thermal analysis

In order to follow the progress of cement hydration by analytical techniques, the ongoing hydration reactions must be stopped by complete removal of free water. A comparison between solvent exchange, oven drying and vacuum drying, using thermal analysis, is presented for early-age hydrated cement pastes. Results show that oven drying at 105 °C accelerates hydration, causes dehydration of some hydrated cement phases and favours carbonation. Solvent exchange with ethanol, ether and methanol results in a strong absorption and an incomplete removal of solvents. FT-IR and XRD gave evidence of the formation of carbonate-like phases due to an interaction upon heating, i.e. during thermal analysis, between the strongly absorbed solvents and the cement compounds or hydrates. Vacuum drying reveals reliable results as no interaction products can be formed and the Ca(OH)₂ content, determined by thermal analysis, gives a good approximation of the real amount of Ca(OH)₂.     

Precursor-Derived Si-B-C-N Ceramics: Oxidation Kinetics

The oxidation behavior of three precursor-derived ceramics—Si_4.46BC_7.32N_4.40 (AMF2p), Si_2.72BC_4.51N_2.69 (AMF3p), and Si_3.08BC_4.39N_2.28 (T2/1p)—was investigated at 1300° and 1500°C. Scale growth at 1500°C in air can be approximated by a parabolic rate law with rate constants of 0.0599 and 0.0593 μm²/h for AMF3p and T2/1p, respectively. The third material does not oxidize according to a parabolic rate law, but has a similar scale thickness after 100 h. The results show that at least within the experimental times these ceramics develop extremely thin scales, thinner than pure SiC or Si₃N₄.     

Reinforcement of a Magnesium‐Ammonium‐Phosphate Cement with Calcium Phosphate Whiskers

Self‐setting resorbable phosphate cements are characterized by an excellent biocompatibility and bioactivity. However, poor mechanical properties restrict their application. Most studies which characterize phosphate cements mechanically focus on strength measurements. Examinations of mechanical reliability and facture toughness were hardly performed. In this study, calcium phosphate whisker‐reinforced magnesium‐ammonium‐phosphate (struvite) cements were examined at the whisker–matrix interface and the measured strength, reliability and toughness values were correlated to these observations. Moreover, the toughening mechanisms were evaluated. It was shown that whisker incorporation is not beneficial for material strength. It led to a strength decrease from 29.8 to 21.8 MPa by the incorporation of 15 vol% calcium‐deficient hydroxyapatite (CDHA) whiskers compared to the pure struvite cement. Weibull statistics and microstructural observations revealed that this is caused by the whisker–matrix interface, which acts as a flaw. In contrast with that, the reliability increases upon whisker incorporation. Furthermore, the critical stress intensity factor K_IC as well as the work‐of‐fracture γ_wof increase from 0.52 to 0.60 MPam^1/2 and from 9.5 to 12.9 J/m² by the addition of 15 vol% CDHA whiskers compared to the original struvite cement. It was shown that whisker pull‐out and crack deflection are the main mechanisms responsible for this increase.     

Blast furnace slags as functional fillers on rheological,thermal, and mechanical behavior of thermoplastics

Blast furnace slags (BFS) is a secondary byproduct of iron industry, which has a combination of acidic and basic oxides and show a complex, multiphase structure. If appropriately tailored, BFS could be an effective functional filler, improving the property profile of thermoplastics such as polypropylene (PP) and polystyrene (PS). As a raw material, the proposed filler may introduce both economic and ecological advantages, as it is considered an inexpensive secondary product rather than a natural resource. The current study aims at investigating the effect of incorporating BFS as a micro‐sized filler on the rheological, thermal, and mechanical behavior of PP and PS. BFS types in this study are air‐cooled, crystalline, and amorphous, grounded types. Both types are ground into 71, 40, and 20 μm batches and introduced in 10, 20, and 30 weight fractions via melt kneading. Mixtures are then formed into 4‐mm and 2‐mm thick plates via compression molding. Slight increase in rheological factors is observed with increasing filler loading. BFS hinders the crystallization of PP, resulting in slight increase of crystallization temperatures (T_c) and lowering of crystallization enthalpy (ΔH_c). No significant effect of filler on transition temperatures (T_g) is reported. Mechanically, BFS increases the tensile modulus of PP, but decreases its strength. For PS formulations, a modest toughening effect is observed by slag filler. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43021.     

Didesoxy-Ribonucleoside durch Schmelzkondensation

Dideoxy Ribonucleosides by Fusion Method The dideoxy nucleosides 2 , 4 and 6 are synthesized from the 1-O-acetyl-2,3-dideoxyribose derivatives 1 , 3 and 5 by fusion with chlorinated purines and other nitrogen heterocycles at 110–120°C without added catalyst. The ¹H-NMR and ¹³C-NMR spectra of the compounds are given.     

COMPARISON OF METHODS FOR THE DETERMINATION OF CELL VIABILITY IN STORED BAKER'S YEAST

The classical plate method for discriminating between viable and nonviable yeast cells in stored baker's yeast was compared with dead cell staining techniques using methylene blue and three fluorochrome stains. The increase of dead yeast cells during storage of baker's yeast for up to 16 days at 5°C, 20°C and 35°C was determined. During prolonged storage, especially at 35°C, the death rate increased rapidly and the yeast cake began to soften because of autolysis. In these conditions the choice of method for determining the proportion of dead cells proved to be of great importance. Useful results for yeast stored for some time at 35°C could be obtained only by the fluorochrome technique using primuline, acridine orange or acriflavine as fluorochromes.     

Phase Transformation and Optimized Growth of TFA-MOD REBa2Cu3O7-x Films for Coated Conductors

Several types of REBa2Cu3O7-x (REBCO, RE=Y, Ho etc.) films are prepared on single crystal substrate LaAlO3 by TFA-MOD method. The phase transformation and optimized growth conditions in the crystallization are studied. Compared with SmBCO and GdBCO, high quality YBCO and HoBCO films are relatively easy to produce. It is revealed that the YBCO grains can form at low temperatures such as 730℃ during the initial heating ramp. With a high heating rate of 20 K/min and a low oxygen pressure of 100 ppm, the optimum growth temperature is around 780℃, at which the films show a Jc value of 2.88 MA/cm2. Further decrease of the heating rate may produce the highquality YBCO film with a higher Jc of 3.65 MA/cm2. The temperature dependence of resistances in various magnetic fields up to 9 T shows that the present TFAMOD YBCO and HoBCO films have similar superonducting transition temperature and magnetotransport properties.     

Assessment of alimentary histamine exposure of consumers in Austria and development of tolerable levels in typical foods

Although alimentary intake of histamine can cause intoxication, legal limits for histamine content in the EU, exist for certain seafish species only. The present study suggests tolerable levels for fermented sausage, fish and cheese which are based on relating the amount of histamine not expected to cause any health effects after ingestion to typically consumed amounts of food. Limits of 500 and 400 mg/kg would seem to be justifiable for fermented sausage and cheese, respectively. For fish species other than those already regulated in EU, the “m”/”M” limits of 100 and 200 mg/kg can be adopted. These limits can be met by current food technology.     

Discounting future green: Money versus the environment.

In 3 studies, participants made choices between hypothetical financial, environmental, and health gains and losses that took effect either immediately or with a delay of 1 or 10 years. In all 3 domains, choices indicated that gains were discounted more than losses. There were no significant differences in the discounting of monetary and environmental outcomes, but health gains were discounted more and health losses were discounted less than gains or losses in the other 2 domains. Correlations between implicit discount rates for these different choices suggest that discount rates are influenced more by the valence of outcomes (gains vs. losses) than by domain (money, environment, or health). Overall, results indicate that when controlling as many factors as possible, at short to medium delays, environmental outcomes are discounted in a similar way to financial outcomes, which is good news for researchers and policy makers alike. (PsycINFO Database Record (c) 2010 APA, all rights reserved)