Current status of cataract surgery. Modern methods--internal medicine risk factors and contraindications

Modern cataract surgery is characterized by minimal invasive techniques that have been introduced during the past decade. These include phacoemulsification, capsulorhexis, foldable intraocular lenses and small tunnel incisions. High success rates coupled with low complication rates have resulted in a change in indications--cataract surgery is no longer performed merely to prevent blindness, but also to improve vision in patients whose professional or private visual demands are compromised by the onset of lens opacification. To ensure that their cooperation with the ophthalmic surgeon results in optimal benefit to the patient, it is important for general practitioners and internists to be conversant with the risk factors and contraindications for cataract surgery.     

Feasibility studies of chemical reactions for thermochemical water splitting cycles of the iron-chlorine,iron-sulfur and manganese-sulfur families

The number of chemical reactions in water splitting cycles of the iron-chlorine, iron-sulfur and manganese-sulfur families is quite high from a thermodynamic point of view. Applying chemical engineering criteria to the reactions allows the cancelling of unfavorable steps. The remaining reactions can be systemized to typical groups. Experimental results of these groups of reactions are presented, depending on temperature, ratio of reactants and reaction performance. The results are discussed with respect to the performance of the chemical reactions in water splitting cycles.     

Bücherschau

Ohne Zusammenfassung     

Low-temperature thermal conductivity of diolmodified epoxies

Summary The thermal conductivity at low temperatures (between 0.5 K and 100 K) was measured for diolmodified epoxies. Diglycidyl ether of bisphenol A (DGEBA) was modified for this purpose by aliphatic diols with the structure HO-(-CH₂-)_n-OH in the presence of catalyst (either N,N-dimethyl benzylamine or magnesium perchlorate). Sample series with diols of n=4,8 and 12 were synthesized and measured. The results at T<20K shows a clear dependence of the thermal conductivity values on the chain length of the diols. The increasing amount of diol in the epoxies cause a larger change on these values in the same temperature range.     

Zur copolymerisation von α-methylstyrol und butadien. V. Bestimmung der chemischen heterogenität durch gelchromatographie

The distribution function of the compositional heterogeneity of copolymers from α-methyl styrene and butadiene has been determined from gel permeation chromatography by detection of refractive index and ultraviolet absorption.     

A study on the biosynthesis ofcis-9,10-epoxyoctadecanoic acid

Preliminary studies show that red stem, rust-infected wheat plants provide a means for investigating the biosynthesis of epoxy fatty acids. The incorporation of 1-¹⁴C-acetate intocis-9,10-epoxyoctadecanoic acid occurs at the stage of the infection when sporulation is proceeding, and at the same stage there is at least a fourfold increase in the synthesis of other fatty acids. The epoxy acid appears to be formed by the condensation of acetate units in a process that requires oxygen and is not stimulated appreciably by light. Labeled stearic and oleic acid are also incorporated into the epoxy acid without undergoing β-oxidation. The rate of conversion of oleic acid is greater than stearic acid, thus indicating that oleic acid is an immediate precursor to 9,10-epoxyoctadecanoic acid. Published with the approval of the director as Paper. No. 2161. Journal Series, Nebraska Agricultural Experiment Station.     

Etude electrochimique de la corrosion d'acier massif et d'acier fritte,en milieu acide sulfurique,avant et apres chromisation

Chemical vapor deposition (C.V.D.) of chromium on bulk steel and on sintered steel, increases the corrosion resistance at first sight, if results of potentiokinetic polarisation in a normal sulfuric acid solution are only considered. Nevertheless a decrease of the polarisation resistance and a localized corrosion occur on chromised samples after a few hours of immersion in acid solution.