Fungizide und bakterizide Anstrichmittel — neue Wirkstoffe für Öl- und Kunstharz-Lacke

Fungicidal and Bactericidal Paints — New Additives for the Oil and Synthetic Resin Lacquers New fungicides, which replace completely the mercury additives in oil, alkyd and synthetic resin lacquers, were developed. In contrast to the mercury additives, they can also be used in the stoving lacquers. They are only of limited use in insulating varnishes. The experience with these additives in different lacquer systems is reported. A combined testing method can give a practicable judgement about the fungicidal activity of such paints in a short time.     

Optimality criteria for the components of anisotropic constitutive matrix

In a free material formulation, the problem of minimizing a weighted sum of compliance’s from multiple load cases, subject to an active constraint on material volume, is solved in a formulation with two optimality criteria. The first optimality criterion for the distribution of material volume densities is equal value for the weighted elastic energy densities, as a natural extension of the optimality criterion for a single load case. The second optimality criterion for the components of a constitutive matrix (of unit norm) is proportionality to corresponding weighted strain components with the same proportionality factor \(\widehat \lambda \) for all the components, as shortly specified by \(C_{i j k l} = \widehat \lambda \sum _{n} \eta _{n} (\epsilon _{i j})_{n} (\epsilon _{k l})_{n}\) , in traditional notation (n indicate load case). These simple analytical results should be communicated, in spite of the practical objection against design for weighted sum of compliance’s, as compared to worst case design and design considering strength. The application of the approach of the two optimality criteria is illustrated by a 2D example with 8 load cases. Stable and fast convergence is shown.     

Determination of local hydrodynamic parameters in bubble columns by the electrodiffusion method with oxygen as depolarizer

An electrodiffusional three-segment probe was developed with which local axial and radial liquid velocities can be determined. Application of this probe in gas-liquid flow yields information on local gas hold-up. In coalescing media the commonly used redox-system Fe(CN) ₆ ³⁻ /Fe(CN) ₆ ⁴ should be replaced by dissolved oxygen as depolarizer. Measurements of local axial and radial liquid velocity and turbulence intensity in different bubble columns (D = 150 and 600 mm) showed good agreement with data obtained by hotfilm anemometry. This paper was presented at the International Workshop on Electrodiffusion Diagnostics of Flows held in Dourdan, France, May 1993.     

Influence of carbonate intercalation in the surface-charging behavior of Zn–Cr layered double hydroxides

The influence of interlayer composition in the surface charge and reactivity of layered double hydroxides (LDHs) has been explored. With this purpose, a chloride-intercalated Zn–Cr-LDH has been synthesized by the constant pH coprecipitation method and afterwards exchanged with carbonate to obtain solids with different Cl^?/CO₃^2? ratios. The solids structure has been characterized by elemental chemical analysis, powder X-ray diffraction and infrared spectroscopy, while its surface-charging behavior and reactivity have been studied by acid–base potentiometric titrations and electrophoretic mobility determinations. The chloride-intercalated sample shows an increasing hydroxyl adsorption with increasing pH and decreasing support electrolyte concentration and the particles present positive electrophoretic mobility in the measured pH range. As carbonate content increases in the samples, the total OH^? uptake diminishes and the samples show an isoelectric point at pH around 10. When the gallery is totally occupied by carbonate anions, the OH uptake vs. pH curves registered at different electrolyte concentrations merge at around pH 10. A LDH–water interface model has been used to give an interpretation to the experimental data. The model indicates that as carbonate content increases, the sample behavior becomes similar to that of a metal (hydr)oxide and that surface (bi)carbonate anions undergo acid–base reactions.     

Assignment of the nonexchanging protons of the alpha-spectrin SH3 domain by two- and three-dimensional 1H-13C solid-state magic-angle spinning NMR and comparison of solution and solid-state proton chemical shifts

The assignment of nonexchanging protons of a small microcrystalline protein, the alpha-spectrin SH3 domain (7.2 kDa, 62 residues), was achieved by means of three-dimensional (3D) heteronuclear (1H-13C-13C) magic-angle spinning (MAS) NMR dipolar correlation spectroscopy. With the favorable combination of a high B(0)-field, a moderately high spinning frequency, and frequency-switched Lee-Goldburg irradiation applied during 1H evolution, a proton linewidth < or =0.5 ppm at 17.6 Tesla was achieved for the particular protein preparation used. A comparison of the solid-state 1H chemical shifts with the shifts found in solution shows a remarkable similarity, which reflects the identical protein structures in solution and in the solid. Significant differences between the MAS solid- and liquid-state 1H chemical shifts are only observed for residues that are located at the surface of the protein and that exhibit contacts between different SH3 molecules. In two cases, aromatic residues of neighboring SH3 molecules induce pronounced upfield ring-current shifts for protons in the contact area.     

Use of NMR imaging to measure interfacial properties of asphalts

An NMR imaging method that allows for direct calculation of interfacial surface tensions of asphalts is described. The method is based upon acquiring NMR images of water drops on the surface of asphalt as a function of time. By expressing the contact angle for the water drop either in terms of Young's equation, or the liquid lens equation for the initial placement of the water drop on the asphalt surface, and for a later time when the water drop has penetrated below the asphalt surface, two equations that incorporate the asphalt-air surface and asphalt-water interfacial tensions are obtained which can be solved analytically. The NMR imaging method was used to determine the surface tensions of the eight Strategic Highway Research Program (SHRP) core asphalts at 25 °C. Asphalt-water interfacial tension values ranged from 25 to 40 dynes/cm, and asphalt-air surface tension values ranged from about 38-50 dynes/cm. These results are in general agreement with other asphalt surface tension measurements that have been made using the du Noüy ring tensiometer, or the Wilhelmy Plate method. Spreading coefficients and capillary numbers derived from the surface tension calculations are also reported.     

Intercellular junctions in FANFT-induced carcinomas of rat urinary bladder in tissue culture: in situ thin-section, freeze-fracture, and scanning electron microscopy studies.

This paper describes a set of simple methods for comparative light and electron microscopy studies on tissue cultured tumour cells derived from both noninvasive and invasive carcinogen-induced rat urinary bladder carcinomas. Cells are grown on Thermanox plastic coverslips and fixed in situ. Each plastic coverslip is then divided with scissors into four parts: the first is processed for light microscopy, the second for thin-section electron microscopy, the third for freeze-fracture electron microscopy, and the fourth for scanning electron microscopy. In some experiments, portions of the culture which have first been examined by light microscopy are subsequently prepared for electron microscopy. In this way, the culture conditions are kept constant and comparison of structural features (i.e. intercellular junctions) by several preparative techniques is possible. Noninvasive and invasive rat bladder tumour cells, characterized by numerous pleomorphic microvilli, have normal zonulae occludentes at the apices of lateral surfaces of tumour cells in all cultures. In some areas of invasive tumour cells, occludens junctions are focally attenuated, consisting of only one or two strands, and occasionally the strands are discontinuous. Gap junctions, type PF-1, as well as numerous demosomes are present in all cell lines. Thus, intercellular junctions in noninvasive and invasive rate bladder epithelial cell lines bear a striking resemblance to those previously described in the comparable solid primary tumours. These culture systems may be useful for studying factors which influence the formation of intercellular junctions during malignant transformation.