Polydepsipeptides I. Synthesis and Characterization of Copolymers of α-Amino and α-Hydroxy Acids

Copolymers of the type were synthesized and characterized. The syntheses of these copolymers were achieved by copolymerization of an α-amino acid N-carboxy anhydride and an α-hydroxy acid anhydrosulfite in the presence of a catalyst. The copolymers were characterized by spectroscopic methods including infrared, circular dichroism and nuclear magnetic resonance. Specific cleavage of the ester bonds by hydroxylamine in the cold confirmed the A-B block structure where the A represents the poly(amino acid) segment and the B indicates the polyester segment. Measurements by nmr and viscosity indicate that the blocks consist of short chain lengths.     

Bacteriophages as viral pollution indicators

f2 Phage, attenuated Polio I (LSC) strain introduced daily to a 350 l. experimental oxidation pond showed no decrease in bacterial viruses f2 or other coliphages or Polio I strain.Ratios of coliphages to human enteric viruses ranged in flood waters from concentrations as low as 1:1 to as high as 10³:1; in wastewater at various seasons the ratio was 10⁵:1; in trickling filter effluents in winter it was 10⁴:1; in spring 10⁵:1, in summer and fall 10⁴:1, in oxidation pond effluents in winter 10³:1; in spring 10⁴:1; and in summer and fall 10³:1. Out of three epidemics in small communities caused by failure of water supply, coliphages were found to be positive. At the same time only two samples of human enteric viruses were positive (the third was contaminated with yeasts).Chlorination experiments using the experimental oxidation pond showed that f2 was most resistant, MS₂ was very resistant, and coliphages were more resistant than attenuated Polio I virus. Experiments with the oxidation pond effluents showed that coliphages were at least as or even more resistant to chlorine than human enteric viruses.     

Absorption of a multicomponenet gaseous mixtures in the presence of instantaneous surface reaction

The rate of absorption from a multicomponent gaseous mixture into a flowing stream in the presence of instantaneous surface reaction is investigated. This is effected by using the generalized Fick's Law for multicomponent diffusion and also by applying the approximate approach based on the assumption that the concentrations of the reactive species are small. Constant properties are assumed for the mixture which are taken at a reference state. As an example, the absorption of C0₂-H₂S and C0₂-H₂ from air are considered. The results show that when the binary diffusion coefficients of the species in the inert gas are greatly different, the error introduced in calculations based on the “Low Concentration” approach is quite appreciable.     

Introduction of Formal Reliability Engineering in Israel

During my sabbatical leave in Israel, I approached reliability engineering in a number of ways. The papers I delivered in conferences, lectures, workshops, short courses, in-plant training, and indoctrination in reliability engineering appreciably increased interest in the reliability discipline. Engineers in Israel for the first time took the 1981 American Society for Quality Control (ASQC) examination for ASQC certification as reliability engineers. The results of the 1981 April examination were gratifying: 11 passed the examination and were awarded the CRE (ASQCCertified Reliability Engineer).     

Effect of Molybdenum on Metallurgical and Wear Properties of Fe–Cr–C Hard facing alloy

Protection of Metals and Physical Chemistry of Surfaces - In this research, Surface hardening was performed by two types of Flux Cored Arc Welding (FCAW) filler metals based on Fe–Cr–C...     

Skin smoothing effects of Dead Sea minerals: comparative profilometric evaluation of skin surface

The skin smoothing effects of three different liquid gels were compared on 20 mature women. Treatment applications were performed twice a day over a period of 4 weeks, and the skin roughness parameter (Rz) of all test participants was determined at the beginning and at the end of the study using a computer-aided laser profilometry, in accordance with DIN 4768 ff. At the end of the application period, the liquid gel with 1% of a Dead Sea mineral solution had an average skin roughness parameter reduction of 40.7%. The liquid gel without mineral additives showed an average reduction in skin roughness of 27.8%. The control gel without anti-wrinkle agents or the additives showed an average reduction of only 10.4%.