Wirkung von N-Trichlormethylthio-tetrahydrophthalimid auf Weinhefen

N-Trichlormethylthio-tetrahydrophthalimid (NTT) ist in mehreren käuflichen Fungiziden enthalten, die im Rebschutz verwendet werden. Diese Substanz ist infolge der Inaktivierung einiger glykolytischer Enzyme als wirksamer Inhibitor der Weinhefengärung anzusprechen. Versuchergebnisse mit Atmungs-Hefentypen weisen auch auf Eingriffe von NTT an verschiedenen Stellen der oxidativen Phosphorylierung hin. Die Inhibition dieses Vorganges sowie der Glykolyse beruht auf einer Abänderung der Proteine, die für ihre katalytische Aktivität Thiolgruppen benötigen. Als Folge mehrfacher Eingriffe von NTT in den energetischen Stoffwechsel der Hefen kommt es zur Hemmung biosynthetischer Prozesse und damit auch zur Einstellung des Zellwachstums. Hierauf deuten die Ergebnisse von Untersuchungen über die Aufnahme 14C-markierter Präkursoren der Protein- und Nukleinsäuresynthese hin. Es werden ferner Angaben mitgeteilt, die es ermöglichen, die Hemmwirkung verschiedener Fungizidpräparate des Handels gegenüber Hefen zu vergleichen. Die Bedeutung der Hefen als Modellorganismen zur Aufklärung des Wirkungsmechanismus fungitoxischer Substanzen wird unterstrichen.Effect of N-trichloromethylthio-tetrahydropbtbalimide on wine yeastsN-trichloromethylthio-tetrahydrophthalimide (NTT), an active component of many commercial fungicidal preparations used in viticulture, is a powerful in hibitor of yeast fermentation due to the inactivation of some glycolytic enzymes. In experiments especially with respiratory yeast types the results obtained show also interferences of NTT with the oxidative phosphorylation. The inhibition of this process and also of glycolysis is a result of modificaticn of proteins requiring thiol groups for their catalytic activity. As a consequence of the multitarget effect of NTT on yeast energy metabolism, biosynthetic processes are inhibited and, finally, yeast growth is blocked. These facts are indicated by the results obtained from study of NTT influence on incorporation of 14Clabelled precursors of both protein and nucleic acid biosynthesis. Data included in the paper make it also possible to compare the antiyeast activities of different types of commercial fungicides. The importaRce of yeasts as a model for the elucidation of the mode of action of antifungal substances is emphasized

Barkhausen noise emission of AISI 304 stainless steel originating from strain induced martensite by shot peening

This study deals with magnetic Barkhausen noise emission produced by strain-induced martensite generated during shot peening of austenitic AISI 304 stainless steel. The transformation from the paramagnetic to ferromagnetic state and the corresponding birth of the magnetic domain structure are important with respect to irreversible motion of domain walls and the corresponding Barkhausen noise emission. Barkhausen noise is investigated and explained with respect to the residual stress state as well as the micro-structure expressed in terms of the martensite fraction, its crystallite size, preferred orientation, surface topography, and microhardness. The strength of the Barkhausen noise is mainly linked with the number of shot peening cycles, corresponding Almen intensity, and the associated volume fraction of strain-induced martensite as well as the extent of its depth. The role of the residual stress state in the martensite phase is minor. Surface strengthening expressed in terms of the microhardness in the near-surface region is very high for the medium shot peening intensity. A remarkable decrease in the near-surface microhardness as well as the presence of heavily thinned folds indicate over shot peen-ing and surface microcracking in the case of a longer shot peening time and the corre-sponding higher Almen intensity.Web of Science2076274

Grain Refinement after Various Thermo-Mechanical Treatments in AZ80 and ZK60 Magnesium Alloys

The effect of thermal processing prior to severe plastic deformation by extrusion and swaging on grain refinement in ZK60 and AZ80 alloys was studied. The alloys received in direct-chill cast condition were homogenized at 415C and annealed (over-aged) at temperatures from 200 to 380°C. Both the direct-hill cast and over-aged conditions were extruded at T = 300C using an extrusion ratio of ER = 19. Hot extrusion resulted in substantial grain refinement in both cases, the effect being stronger in the over-aged material. The extruded bars were severe plastically deformed at 250C by swaging. Swaging refined further the grain size depending on the deformation ratio (number of passes). At optimal processing conditions the grain size was 450 nm and 570 nm for the AZ80 and ZK60 alloys, respectively

Effect of Microstructure on the Corrosion Resistance of the AE42 Magnesium Alloy Processed by Rotary Swaging

Microstructure and corrosion resistance of the AE42 commercial alloy processed by extrusion and rotary swaging were investigated. Microstructure characterization showed an increasing volume fraction of the refined grains with increasing stage of swaging processing. However, their presence was limited solely to the peripheral ring of ≈1 mm in all studied conditions of swaged material. Corrosion resistance investigation showed continuous decrease of polarization resistance that was attributed to the grain refinement and insufficient homogenization of the alloying elements during the swaging process

Grain Refinement after Various Thermo-Mechanical Treatments in AZ80 and ZK60 Magnesium Alloys

The effect of thermal processing prior to severe plastic deformation by extrusion and swaging on grain refinement in ZK60 and AZ80 alloys was studied. The alloys received in direct-chill cast condition were homogenized at 415C and annealed (over-aged) at temperatures from 200 to 380°C. Both the direct-hill cast and over-aged conditions were extruded at T = 300C using an extrusion ratio of ER = 19. Hot extrusion resulted in substantial grain refinement in both cases, the effect being stronger in the over-aged material. The extruded bars were severe plastically deformed at 250C by swaging. Swaging refined further the grain size depending on the deformation ratio (number of passes). At optimal processing conditions the grain size was 450 nm and 570 nm for the AZ80 and ZK60 alloys, respectively

Understanding the interrelationship between the synthesis of urea and gluconeogenesis by formulating an overall balanced equation

Understanding the interrelationship between the synthesis of urea and gluconeogenesis by formulating an overall balanced equation. Adv Physiol Educ 41: 286–290, 2017; doi: 10.1152/advan.00180.2016.—It is well known that a strong metabolic interrelationship exists between ureagenesis and gluconeogenesis. In this paper, we present a detailed, overall equation, describing a possible metabolic link between ureagenesis and gluconeogenesis. We adopted a guided approach in which we strongly suggest that students, when faced with the problem of obtaining the overall equation of a metabolic pathway, carefully account for all atoms and charges of the single reactions, as well as the cellular localizations of the substrates, and the related transport systems. If this suggestion is always taken into account, a balanced, overall equation of a metabolic pathway will be obtained, which strongly facilitates the discussion of its physiological role. Unfortunately, textbooks often report unbalanced overall equations of metabolic pathways, including ureagenesis and gluconeogenesis. Most likely the reason is that metabolism and enzymology have been neglected for about three decades, owing to the remarkable advances of molecular biology and molecular genetics. In this paper, we strongly suggest that students, when faced with the problem of obtaining the overall reaction of a metabolic pathway, carefully control if the single reactions are properly balanced for atoms and charges. Following this suggestion, we were able to obtain an overall equation describing the metabolic interrelationship between ureagenesis and gluconeogenesis, in which urea and glucose are the final products. The aim is to better rationalize this topic and to convince students and teachers that metabolism is an important and rewarding chapter of human physiology