Beobachtung des Stickstoffstoffwechsels bei Leguminosen mittels 15N

Es war Ziel dieser Arbeit, zu ermitteln, welchen Einfluß höhere Dosen von Stickstoffdüngemitteln in Form von KNO₃ auf die Menge des in der Pflanze fixierten Luftstickstoffs haben. Als Versuchspflanze wählten wir Pferdebohnen (Vicia faba, Chlumetzer Abart) wegen ihrer vielseitigen Verwendung in der Landwirtschaft und ihrer besonderen experimentellen Eignung.     

Analysis of PCBs in Biotic Matrices by Two-Dimensional GC-ECD

Abstract

The suitability of three GC-ECD systems for the separation of a model mixture containing various congeners of PCBs together with persistent chlorinated aromatics (pesticides and their metabolites, industrial chemicals) was tested. Analyses were performed on two parallel capillaries, the stationary phase of one of them was always in routine practice very common 5% phenyl-methylpolysiloxane, the second one was either 50% phenylmethylpolysiloxane or 7% phenyl-7% cyanopropyl-methylpolysiloxane. The number of unresolved (coeluted) analytes was significantly reduced in these systems and thus unbiased quantitation of PCBs and other components used for regulation was possible. The utilization of this type of multidimensional chromatography for rapid and reliable analysis of real samples (fish oil, human fat) was documented.     

The effect of drying method on the properties and nanoscale structure of cellulose whiskers

Cellulose whiskers were prepared from wood- and cotton-based microcrystalline cellulose and dried by two methods: freeze-drying or air-drying. The effect of drying method on the properties and structure of the whiskers were studied. Furthermore, the influence of the source of cellulose on the nanoscale structure was investigated. Drying method was observed to slightly influence the thermal stability of cellulose whiskers, whereas the char residue varied significantly depending on the drying process performed. Small- and wide-angle X-ray scattering and solid state nuclear magnetic resonance spectroscopy were used to examine the crystallinity and nanoscale structure of the dried whiskers. It was observed that the crystal structure and crystallinity of cellulose whiskers remained during all treatments, whereas their nanoscale structure was significantly influenced by drying method, neutralization, and source of cellulose. Relationships between thermal behavior and nanoscale structure were reported and discussed.     

DSC study of stabilizing effect of antioxidant mixtures in styrene-butadiene rubber

The type of cooperation between antioxidants in the binary mixtures of four substituted diphenylamines and phenotiazine in the stabilization of styrene-butadiene rubber has been tested. Thermooxidation of the samples has been studied by differential scanning calorimetry under non-isothermal conditions. The protection factors of the individual stabilizers and their mixtures were determined. The synergy factors were applied to asses the type of cooperation of antioxidants in the mixtures. From their values it can be concluded that the type of cooperation depends on temperature. The highest synergistic effect has been observed for the mixture of phenotiazine and [4-(1-methyl-1-phenyl-ethyl)-phenyl]-phenylamine.     

Numerical simulation for the temperature changing rule of the crude oil in a storage tank based on the wavelet finite element method

In order to study the temperature changing rule of the crude oil in the storage tank, the wavelet finite element method, the traditional finite element method and the test were used to carry out the numerical simulation. Firstly, the thermal wavelet finite element was put forward established based on thermal finite element theory and the wavelet theory. And the computational model and three boundary conditions were established. And then the temperature changing rule of the crude oil in the storage tank in 24 h for three boundary conditions was obtained by using three methods, and the results showed that the wavelet finite element method had advantages in the numerical analysis of the temperature changing rule of the crude oil in the storage. And then the temperature distribution rule of the crude oil in the storage tank under different conditions in 5 h was obtained. And the temperature changing mechanism of the crude oil was summarized finally.     

Quantification methods of amorphous/crystalline fractions in high-energy ball milled pharmaceutical products

In this work, thermoanalytical, diffractometry, and microscopy measurements have been performed in order to characterize the effect of high energy milling on a drug active in the migraine prophylaxis and smoke cessation. We can assert that the mechanical treatment induces only a partial amorphisation of the solid phase, in particular it reduces the crystal order by producing lattice defects which propagate from the surface to the bulk crystal. For this reason, the DSC is able to detect the presence of ordered solid, while the powder X-ray diffractometry, because of its low penetration depth, does not reach the crystalline core of the particles.     

A corresponding states principle-based equation for the surface tension of Alkenes

This study presents a new formula for the surface tension prediction of alkenes. As a first step, an analysis of the available data of the experimental surface tension data for alkenes was performed. The experimental data were collected, after a careful literature survey, for the following pure fluids: propene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-tetradecene, and 1-pentadecene. Then, the experimental data were regressed with the most reliable semi-empirical correlating methods based on the corresponding state theory existing in the literature. As a final step, an analysis of the available data of the experimental surface tension data for alkenes was performed starting from the two recently proposed equations for the prediction of the surface tension of refrigerants based on the corresponding states principle. To minimize the deviation between the predicted data and the experimental data and to find the optimal equation coefficients for experimental data regression, a (μ + λ)-evolution strategy was adopted. The analysis showed that the equation that gave the best results for the prediction of the surface tension of alkenes was the one with a very limited number of parameters. The finally proposed equation is very simple and gives a noticeable improvement with respect to the existing equations. It is based on the corresponding state principle, containing the acentric factor, the critical temperature, and pressure.     

Some remarks on equilibrium state in dynamic condition

For dehydration of CaC₂O₄·H₂O and thermal dissociation of CaCO₃ carried out in Mettler Toledo TGA/SDTA-851^e/STAR^e thermobalance similar experimental conditions was applied: 9–10 heating rates, q = 0.2, 0.5, 1, 2, 3, 6, 12, 24, 30, and 36 K min⁻¹, for sample mass 10 mg, in nitrogen atmosphere (100 ml min⁻¹) and in Al₂O₃ crucibles (70 μl). There were analyzed changes of typical TGA quantities, i.e., T, TG and DTG in the form of the relative rate of reaction/process intended to be analyzed on-line by formula (10). For comparative purposes, the relationship between experimental and equilibrium conversion degrees was used (for P = P^ominus P = P^{{ominus}} ). It was found that the solid phase decomposition proceeds in quasi-equilibrium state and enthalpy of reaction is easily “obscured” by activation energy. For small stoichiometric coefficients on gas phase side (here: ν = 1) discussed decomposition processes have typical features of phenomena analyzable by known thermokinetic methods.