High pressure thermal denaturation kinetics of whey proteins

Pressure processing of foodstuff has been applied to produce or modify proteinaceous gel structures. In real pressure processing the treatment is non-isothermal, due to the adiabatic nature of the process and the heat loss from the product to the vessel. In order to estimate the effect of pressurization on milk constituents pressure and temperature dependent kinetics were determined separately from each other. In a detailed kinetic study whey protein isolate was treated under isobaric (200 to 800 MPa) and isothermal conditions (-2 to 70 degrees C), and the resulting degree of denaturation of beta-lactoglobulin A and B and alpha-lactalbumin was analysed. Kinetic parameters of denaturation were estimated using a one step non-linear regression method which allowed a global fit of the whole data set. The isobaric isothermal denaturation of beta-lactoglobulin and alpha-lactalbumin was found to follow third and second order kinetics, respectively. Isothermal pressure denaturation of both beta-lactoglobulin fractions do not differ significantly and were characterized by an activation volume decreasing with increasing temperature from -10 to about -30 ml mol(-1), which demonstrates that the denaturation rate is accelerated with increasing temperature. The activation energy of about 70 to 100 kJ mol(-1) obtained for beta-lactoglobulin A and B is not dependent to a great extent on the pressure which indicates that above 200 MPa denaturation rate is limited by the aggregation rate while pressure forces unfolding of the molecule.     

Contents of heavy metals in tree components of economical important species in relation to their residual utilisation

Zusammenfassung An 7 forstlich genutzten Standortsgruppen mit Kiefern- Fichten-, Eichen- oder Buchenbestockung wurden die Schwermetallgehalte ermittelt. Die Gehalte unterschieden sich je nach Baumart, Baumkompartiment und Standort z.T. erheblich. Bei den Schwermetallen hing die Höhe der Gehalte weniger von der Baumart ab, hier hatte die Belastungssituation des Standortes den stärksten Effekt auf die Elementgehalte. So wiesen beispielsweise nahezu alle Biomassesortimente aus Bergwerks- oder Hüttenregionen deutlich erhöhte Schwermetallgehalte auf, die die Grenzwerte zahlreicher Verordnungen übertreten und die Verwertung verschiedener Biomassesortimente für einzelne Nutzungen einschränken oder verhindern können. Dagegen können die Schwermetallgehalte von Biomassesortimenten gering belasteter Standorte i.d.R. als unbedenklich gelten

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Contents of heavy metals in tree components of economical important species in relation to their residual utilisation

At seven forest site classes with pine, spruce, oak or beech stands the heavy metal contents of the trees were determined. The element contents differed substantially among tree species, tree compartments and forest sites. The amount of heavy metal content depended very little on tree species but mostly on the degree of pollutant inputs. For example, all tree components had high levels of heavy metals when grown on mine sits (open pits) and on close to ore treated areas. Biomass from some of these areas may exceed the limit of allowed values by several folds and thereby may not be allowed to be used for specific purposes. Heavy metal contents of biomass components from unpolluted areas may be low providing no constrain to their use.

     

Are inclined screw blades for vertical grain augers advantageous?

Due to modern technology, screw blades are often manufactured by rolling them out of one single strip of steel. When simultaneously some blade inclination is applied, less residual stresses and/or larger possible ratios between outer and shaft diameter are claimed by some manufacturers, which seems plausible. However, it is sometimes also claimed that the efficiency of the conveyors is increased by such an inclined blade. The underlying idea is that the blade will cause extra pressure between the material to be conveyed and the tube of the conveyor. This in turn would delay the angular speed of the material, thus resulting in a steeper upward motion.In order to investigate this phenomenon, previous investigations based upon the conveyance of a single point mass have been modified for an inclined screw blade. It appeared that such a blade has no significant advantages over a normal one, which was confirmed by a series of tests. For completeness, tests were also carried out with a leading screw, resulting in worse results.In the case that the pitch equals the diameter and for friction coefficients of 0.3 at both screw blade and tube wall, an increase of no more than 5% in capacity will occur, even for blade inclination angles up to 30°. At the same time, however, the efficiency can drop by 15%.     

Wall effects observed in tissue-equivalent proportional counters from 1.05 GeV/nucleon iron-56 particles

A strong overlap between P-glycoprotein (Pgp) and cytochrome P450 3A (CYP3A) substrates and modulators has been reported. To test the hypothesis that CYP3A and Pgp are coordinately regulated, we examined the effects of known inducers of CYP3A (triacetyloleandomycin, rifampicin, dexamethasone, pregnenolone 16alpha-carbonitrile) on Pgp expression in rat liver. We also investigated the gender-specific expression of Pgp and compared its response to dexamethasone between male and female rats. In male rats, western blot analyses showed that rifampicin and dexamethasone caused 50% and 5-fold increases in Pgp levels, respectively. RNase protection assays using gene-specific probes for the three Pgp isoforms revealed a 3-fold increase in mdr2 mRNA levels after dexamethasone administration and a 2-fold increase following rifampicin treatment. Triacetyloleandomycin and pregnenolone 16alpha-carbonitrile had no effect on Pgp expression and mRNA levels. We also observed that the basal level of Pgp was 40% lower in male rats than in females and that mdr2 mRNA levels in male rats were one-half those in females. As opposed to the results in male rats, dexamethasone reduced Pgp expression by approximately 60% and caused a 30% decrease in mdr2 mRNA levels in female rats. Mdr1a was not affected and mdr1b was not detected in female or male rats. We conclude that, at the dosage regimen used, CYP3A and Pgp responses to CYP3A inducers are regulated independently in rat liver. In addition, this study shows that Pgp expression and regulation are gender specific.     

Determination of the place conditioning and locomotor effects of amperozide in rats: A comparison with cocaine.

Amperozide promotes social interactions in rats (Rattus norvegicus) and reduces craving for cocaine and alcohol without producing adverse side effects. Amperozide administration produced a place preference in the dose range from 3.0 to 10.0 mg/kg. Locomotor behavior tended to be suppressed on the days of amperozide pairings, elevated on the days of vehicle pairings, and elevated on test days. Administration of 20.0 mg/kg but neither 2.0 nor 0.2 mg/kg cocaine produced place preference. Rats exhibited a greater place preference for the chamber paired with 2.0 mg/kg and 20.0 mg/kg but not 0.2 mg/kg cocaine compared to the chamber paired with 5.0 mg/kg amperozide. The results indicate that amperozide is appetitive. The most appetitive dose of amperozide (5.0 mg/kg) is less appetitive than the most appetitive dose of cocaine (20.0 mg/kg). More research is needed before conclusions regarding the degree of abuse potential for amperozide can be made. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Zur Bestimmung der Wärmeleitfähigkeit von Eisenschwamm

Messung der Wärmeleitfähigkeit von Eisenschwamm nach der Laserimpuls-Methode bei Temperaturen zwischen 20 und 1400°C. Vergleich der Meßwerte mit der Wärmeleitfähigkeit von Reineisen. Theoretische Überlegungen zum Temperaturverlauf der Wärmeleitfähigkeit des Eisenschwamms.