Kommentar II

Ohne Zusammenfassung     

Niederdruckumkehrosmose mit modifizierten polyacrylnitril-ultrafiltrationsmembranen

The chemical modification of polyacrylonitrile ultrafiltration (PAN-UF) membranes by hydroxylamine yields low-pressure reverse-osmosis (LP-RO) membranes containing amidoxime and hydroxamic acid groups besides nitrile groups. These membranes are positively charged at pH values of 4.0 to 6.5. The water permeability of the membranes decreases from 400 L h^?1 m^?2 to 15 L h^?1 m^?2 (p = 0.3 MPa) by this modification. A comprehensive characterization was carried out by retention curves, IR and NMR spectra, Hg porosimetry, measurement of membrane potentials and separation performance regarding different metal salts. Due to the Donnan exclusion these membranes have a retention of 88% at a filtrate flux of 8 L h^?1 m^?2(p = 0.3 MPa) regarding bivalent metal ions like Ca²⁺ and Mg²⁺ which cause the water hardness. Regarding heavy metal ions like Cu²⁺ and In³⁺ much higher filtrate fluxes from 90 to 100 L h^?1 m^?2 (p = 0.3 MPa) are possible. In water medium without any heavy metal ions the amidoxime and hydroxamic acid groups are hydrolysed to carboxylic acid groups which are able to reject multivalentanions. By this the water softening ability remains.     

Zur Konzentrationsabhängigkeit der Fällungspunkte von Polymerlösungen

The concentration dependence of the cloud points of dilute benzene solutions of polystyrenes with broad and narrow molecular distributions was determined via titration with methanol or isopropanol using visuell determination, colorimetry and light scattering. All methods gave a linear dependence of the volume fraction φFM of the non-solvent from the logarithm of the polymer concentration c_p at the cloud point for three decades of c_p if certain evaluation techniques are used. Light scattering was the most accurate, visuell observation the least accurate method. The slope coefficients k of the function φFM = f(log c_p) depend linearly on 1/M^0,6 for polystyrenes of narrow molecular weight distribution.     

Power comparator based on-site calibration of isolating current transformers

A portable system for on-site calibrations of isolating current transformers in stationary energy meter test systems is described. The uncertainties of the calibration system are in the order of 0.005 % for the ratio error and 0.01 crad for the phase displacement of the current transformer at power frequencies. The power comparator based measurements can be done at test currents from 50 mA to 120 A.     

Wasserstoffbrückenbindungen in Lösungen ortho-phosphorylsubstituierter Phenole

Hydrogen Bonds in Solutions of Ortho Phosphoryl Substituted Phenols In contrast to open-chained phosphoryl-enols 1 the ortho-P(O)-substituted phenols 4 may be conveniently obtained by cleavage of phenol alkylethers. R_f-values (TLC) demonstrate that the phenols 4 exhibit PO ⃛ HO hydrogen bonds in solution if the basizity of the phosphoryl O-atom is sufficient. Electronwithdrawing P-substituents lower the probability of this interaction. δ_OH and P_ka data demonstrate that in dimethylsulfoxide only phosphinoxides 4a–g give PO ⃛ HO bridges. Arylesters of phosphonic acids 4i–k add DMSO-molecules via SO … HO hydrogen bonds. This difference is mainly a result of inductive effects. UV-spectra refer to a probably small contribution of P-phenyl substituents to conjugation.     

Darstellung und 1H-NMR-spektroskopische Untersuchung von β-substituierten Äthylen-phenylphosphinsäure-äthylestern

Preparation and ¹H N.M.R. Spectroscopic Investigation of β-Substituted Ethyl Esters of Ethylene-phenylphosphinic Acid The ethyl ester 3 of diphenylphosphorylmethyl-phenyl-phosphinic acid in benzene reacts regiospecifically and stereoselectively with aldehydes, in presence of sodium hydride, to 2-substituted ethyl esters of trans-ethylene-1-phenylphosphinic acid 8 (E-isomers) in satisfactory yields. The ABX type H-n.m.r. spectra of isolated pure products 8 were analysed. The trans configuration of these compounds is characterized by the specific signal sequence of ethylene proton H_B.     

Application of Prediction Error Filters for the Detection of Weak Teleseismic Events

This paper analyzes how the signal-to-noise ratio (SNR) for digital registrations of weak earthquakes can be enhanced by application of prediction error filters. Two prediction algorithms are considered: A linear prediction filter and an adaptive autoregressive moving average (ARMA) filter. The effects of the filter parameters on the noise suppression rate and on the quality of spectral approximation are discussed. Results are given for broad-band and short period data of the Graefenberg array. The signal-to-noise gains achieved by prediction error filtering are examined for a series of weak events.     

Temperature-enthalpy diagrams of different operating methods in blast-furnace processes

This report is concerned with the representation of temperature profiles for gas and solid in temperature-enthalpy-diagrams for the example of the blast-furnace process. Of particular interest is the point at which the gas and solid temperatures approach each other the most. For this, the temperature profiles for gas and solid are required, which can both be represented as a function of the specific enthalpy of the solid. With such diagrams we are able to judge the effects on process changes with reference to the position and the level of the minimum temperature difference between gas and solid, and to the level of the top-gas temperature and the caloric temperature dominating in front of the air-blast tuyères. In this context the influence of the coke ratio, of the furnace blast temperature, of the oxygen enrichment of the furnace blast, of the specific heat losses, as well as of the injected replacement fuels was studied for the example of pulverized coal and heavy oil. As a rule, the minimum temperature difference is to be found at the beginning of the smelting of the burden. Depending on the change of the process quantities the temperature difference can also arise at the top, as for example during oxygen enrichment.