Das Verhalten von Glas beim maschinellen Geschirrspülen

The Behaviour of Glass in Mechanical Dish-Washing Under the conditions involved in mechanical dish-washing there is only a slight difference in the behaviour of glasses of different compositions. The higher temperatures attained thereby are mostly responsible for the damages to the glass. Alkaline, especially strongly alkaline solutions, attack more than the acidic ones. The percentage of the complaints lodged for the glass damages is still relatively small. However, the rapidly increasing number of household dish-washing machines makes it necessary that everybody concerned should discuss the problem of cloudiness of glass.     

Hydrothermal synthesis, characterization and structure refinement of chlorate- and perchlorate-sodalite

Chlorate- and perchlorate-sodalites were synthesized hydrothermally in the temperature range of 160°C to 500°C. IR absorption bands indicate the enclathration of NaClO₃ (624 cm⁻¹) and NaClO₄ (624 cm⁻¹ and 2050 cm⁻¹) in the sodalite cages. The thermal decomposition has been characterized by simultaneous thermal analysis (TG, DTG, DTA) and high temperature X-ray powder diffraction. The total collapse of the sodalite framework structure and the formation of nepheline could be observed at 750°C and 1100°C for chlorate-sodalite and perchlorate-sodalite, respectively.

The crystal structure has been determined for NaClO₄-sodalite showing cubic symmetry (a₀=9.071 Å, SG P 3n) and complete ordering of Si and Al in the silicate framework; the Si-O-Al angle is 146.7°. The Cl atoms of the enclathrated perchlorate are located at the central positions of the sodalite cages. For the oxygen atoms of the Cl₄⁻ anions the structure refinement led to orientationally disordered sites having a close resemblance to the well-known O(2) positions of basic sodalite Na₈[AlSiO₄]₆(OH)₂·2 H₂O.     

The relationship between the physico-mechanical properties and the filler concentration in the HD polyethylene-dispersed filler system

The relationship of 10 basic physico-mechanical properties and the concentration of the filler is investigated through narrow filling intervals of seven different composite series containing various types of HD polyethylene and different grades of kaolin. A variety of mixing techniques for the preparation of the composites is used, and testing is carried out by applying different techniques and conditions. The investigations show that, in all cases when an identical mixing technique is applied for a given series of composite formulations, the relationship linking the physico-mechanical and dynamic-mechanical G′, G″, and tan δ properties with the concentration of the filler is not a monotonous curve, and displays a multiextermal character. We propose as one possible explanation that a periodic change in the free volume and the content of crystal polyethylene phase exists, as a function of the filling. The nonmonotonous character of the changes of properties is related to the proposed mechanism for the change of the physical structure of composites, which are composed of filler particles coated with n monolayers of polyethylene crystallites, when, as filling continues, periodically new types of filler particles are formed. The nonmonotonous character of the relationship between the properties and the concentration of the filler should be taken into consideration when these relationships are approximated or expressed in a mathematical-analytical form, especially when high amounts of fillers (more than 20 vol %) are used.     

Ultraschallabbau und Mikromorphologie amorpher Hochpolymerer

The microstructure of polydimethylsiloxane and polychloroprene, thermically treated polychloroprene and natural rubber was investigated by ultrasonic degradation and electron microscopy. The rate of ultrasonic depolymerisation in solution was determined by viscosity measurements. The limits of molecular weight were found between about 10000 and 30000. The irradiation times needed differed very much from the investigated polymers. The ultrasonic intensity has no influence on the limit of molecular weight. For thermically not treated polymers was found that following molecular weights are identical: 1. the limiting molecular weight after ultrasonic degradation, measured by viscosimetric method, 2. the molecular weight of tertiary structural units of undegraded and degraded polymer, determined by measuring electron micrographs. The ultrasonic degradation consequently has no influence on the size of tertiary units of a polymer. This result proves that pearlstring-molecules also exist in solution. The result suggests following mechanism of ultrasonic degradation: the molecule resembling a string of pearls is broken at the chain between the spherical units. For thermically treated and not treated polychloroprene the same size of tertiary units was found, but in the thermically treated product there was a big share with smaller structural units.     

Powder mixing in a horizontal batch mixer

The mixing process in a horizontal batch mixer with a twin spiral rotor has been investigated.A mixture of crushed wheat and sodium chloride was mixed in a model mixer. The concentration of sodium chloride in mixture samples was checked as a function of the mixing time and sampling place for various degrees of mixer filling. The sample composition was determined by conductometric determination of sodium chloride in water extracts of the sample. From the values obtained, the mixing degree was calculated as defined by the variation coefficient along the whole mixer, as a function of the mixing time.In analysing the data and empirical correlation between the concentration of component under study and the place and time of mixing, C/C? = f(x, t) was obtained and compared with industrial experiments using radionuclides as tracers.     

The relation between the adsorption characteristics of polar organic compounds (alcohols and acids) and their orientation polarization on activated carbon

The high temperature adsorption of n-alcohols (methanol, ethanol, propanol and butanol) and the aliphatic acids (formic, acetic, propionic and buteric) was studied on steam activated carbon using micro Chromatographic technique. In the light of the theory of polarization, it was found that the adsorption of these polar alcohols depends on their orientation polarization. A relation was found between the high temperature adsorption characteristics and the orientation polarization of the alcohols and the aliphatic acids on activated carbon.     

The deleterious effects of human erythropoietin gene driven by the rabbit whey acidic protein gene promoter in transgenic rabbits

Human erythropoietin (EPO) gene and cDNA associated with the rabbit whey acidic protein (WAP) gene promoter were used to tentatively produce the recombinant protein in milk of transgenic mice and rabbits. Several gene constructs showed good efficiency in the mouse mammary cell line HC11. None of them was able to direct the expression of the hormone at a concentration higher than 50 micrograms/mL in mouse and rabbit milk. With one of the construct, the rabbits had an abnormally high amount of red blood cells irrespectively of their sex, they could not reproduce and no milk could be obtained from them. These animals died prematurely. In these animals, the EPO gene was therefore expressed at a low but supraphysiological level in organs other than the mammary gland. These experiments show that transgenic animals obtained with gene constructs which do not contain insulators cannot be used as living fermentors to produce human erythropoietin in their milk at an industrial scale.     

Corrosion of yttria-fully stabilized zirconias in molten fluorides

Yttria-fully stabilized zirconia ceramics were manufactured from home-made and commercially available powders and were sintered under different conditions. The ceramics were immersed in the corrosive environment of molten LiF, NaF, KF (FLINAK) eutectic for up to 360 h from 700–900 °C. The changes caused in the crystal structure were probed with laser Raman spectroscopy and X-ray diffraction. The degree of corrosion (phase transformation) depends on immersion period, FLINAK temperature, and ceramics microstructure. From the tested ceramics, ZrO₂-8 mol % Y₂O₃ with a grain size larger than 8 μm and having zero open porosity, exhibits the best resistance to the corrosive influence of FLINAK.