The Precipitation of Alumina Hydrate from Aluminate Solutions in the Presence of Some Higher Alcohols and Starch

The effect of low concentrations of isopropyl alcohol, n -butyl alcohol, isovaleryl alcohol, glycol, glycerol , glucose and starch on the rate of precipitation of alumina hydrate from metastable aluminate solution s was studied. The changes of electric conductivity during the precipitation were also measured. Only glycol accelerated the precipitation of alumina hydrate at concentrations covered by the experiments; the other substances retarded the precipitation. Glycerol in a concentration of about 0.2 M/ 1., glucose in a concentration of 6.7 g./ 1., and starch in a concentration of 6.7 g./l, prevented the precipitation

On the Changes of Viscosity Preceding the Precipitationof Aluminium Hydrate from Aluminate Solutions

In order to ascertain whether and in what way the structure of clear aluminate solutions is modified prior to the precipitation of aluminium hydrate, the viscosity and specific gravity of these solutions were measured from the moment of their preparation to the moment of incipient precipitation

Investigation of Sintering Kinetics of Magnesium Titanate

Obtaining new materials including sintered electronic materials using different procedures is the consequence of long complex and expensive experimental work. However, the dynamics of expansive development of electronic devices requires fast development of new materials, especially sintered oxide materials. The recent rapid development of electronics is among other things due to development and improvement of new components based on titanate ceramics. Research in this work has included an experimental study of the synthesis of dielectric ceramics in the system MgCO3 - TiO2. Starting powders were mechanically activated by milling in a high energy planetary mill for different times. Samples were prepared for isothermal sintering at 1100 degrees C by dual pressing of powders into cylindrical samples in a hydraulic press

Kinetic Measurements on Alkylammonium Halides

Chemical relaxation measurements are reported on alkylammonium halides having carbon atoms in the alkyl chain from 10 to 16. Two relaxation times were observed for most of the studied systems. Data are interpreted on the basis of a theory recently developed by G. Aniansson and S. Wall. According to this theory, the fast process is due to a shift of the micellar distribution curve. The residence time of a detergent molecule in the micelle and the half width of the micellar distribution curve are obtained from the fast process. The slow relaxation process is characteristic for the change of the concentration of micelles and permits the evaluation of the concentration of the micellar nuclei and their thermodynamic properties. The obtained results are compared with available data on alkylpyridinium halides

Microbiological quality and inhibitory potential of selected Croatian apiary honeys

The quality of honey is mainly determined by its sensorial, chemical, physical and microbiological properties. The purpose of this research was to evaluate microbiological properties of 72 honey samples and to determine the number and/or presence of aerobic mesophilic and spore-forming bacteria, moulds, yeasts, sulphite-reducing clostridia, bacteria from the Enterobacteriaceae family and Staphylococcus aureus. Microbiological quality of tested samples was considered good and pathogenic bacteria were not present. Inhibitory potential of selected honey samples was also investigated. Among tested honey concentrations (0.1%, 5%, 10%, 25%, 50% and 75%), the final concentration of 75% had the highest potential. Honeydew and chestnut honey exhibited the strongest inhibitory effect against tested bacterial species, while the lowest inhibition was exhibited by linden (lime tree) honey. Comparing the samples of the same honey type, considerably different inhibitory activity can be detected. Overall, the most sensitive bacterium to the inhibitory effect of tested honey samples was S. aureus, while the most resistant one was Enterococcus faecalis

Identification of deep trap levels from thermally stimulated current spectra of semi-insulating CdZnTe detector material

Deep trap levels in the semi-insulating (SI) CdZnTe detector material were characterized by simultaneous multiple peak analysis based on thermally stimulated current (TSC) measurements. In our TSCs that have been published previously electron hole pairs were created through the use of proton beam irradiation. Charge carriers were captured in deep traps and afterward released by thermal emission, which was recorded in the 90–300 K range. We showed that the obtained TSC spectra could be well fitted with a unique set of 14 different deep traps, which were all simultaneously and completely characterized. The obtained trap data are in good accordance with earlier deep trap characterizations of the other authors obtained on similar SI CdZnTe materials using different methods

Hepatic Cytochrome P-450. A Proton Magnetic Relaxation Study of Microsomal, Solubilized and Partially Reconstituted Enzyme System

The longitudiJ:ial proton magnetic relaxation times, Ti, were measured from -5 to 40 °c for microsomal, solubilized and reconstituted cytochrome P-450 obtained from phenobarbital-induced rat livers. The paramagnetic contribution to the rates was derived by subtraction of the rates measured on dithionite-CO-reduced samples. The same values were obtained for microsomal P-450 on reduction with NADPH. PMR titratio.n by KCN yielded a dissociation constant of about 30 mM. This is three orders of magnitude larger than for metmyoglobin. It is concluded that the measured PMR rates are most likely due to the P-450 (and P-420) haem-iron while the 300/o non-haem iron found in both the microsomal and s olubilized P-450 is .ineffective for the PMR rates. These rates increase several times on isotopic dilution (D20 for H20) with the microsomes and diminish for the solubilized samples. Microsomes show 170/o residual, encaged, H20. Most of their paramagnetic PMR rate is due to the parama.gnetic iron located on the outside of microsomes. This is demonstrated by measurements with deuterated samples to which 190/o H20 had been added. Hence, the solubilized P-450 is homogeneous regarding PMR, but the microsomes are not