G?rungserscheinungen

Ohne Zusammenfassung     

Identification of Entry Inhibitors against Delta and Omicron Variants of SARS-CoV-2

Entry inhibitors against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are urgently needed to control the outbreak of coronavirus disease 2019 (COVID-19). This study developed a robust and straightforward assay that detected the molecular interaction between the receptor-binding domain (RBD) of viral spike protein and the angiotensin-converting enzyme 2 (ACE2) receptor in just 10 min. A drug library of 1068 approved compounds was used to screen for SARS-CoV2 entry inhibition, and 9 active drugs were identified as specific pseudovirus entry inhibitors. A plaque reduction neutralization test using authentic SARS-CoV-2 virus in Vero E6 cells confirmed that 2 of these drugs (Etravirine and Dolutegravir) significantly inhibited the infection of SARS-CoV-2. With molecular docking, we showed that both Etravirine and Dolutegravir are preferentially bound to primary ACE2-interacting residues on the RBD domain, implying that these two drug blocks may prohibit the viral attachment of SARS-CoV-2. We compared the neutralizing activities of these entry inhibitors against different pseudoviruses carrying spike proteins from alpha, beta, gamma, and delta variants. Both Etravirine and Dolutegravir showed similar neutralizing activities against different variants, with EC50 values between 4.5 to 5.8 nM for Etravirine and 10.2 to 22.9 nM for Dolutegravir. These data implied that Etravirine and Dolutegravir may serve as general spike inhibitors against dominant viral variants of SARS-CoV-2.     

Indications for the applicability of element signature analysis for the determination of the geographic origin of dried beef and poultry meat

In order to determine the geographic origin of poultry and dried beef, concentrations of a total of 72 different elements (occasionally represented with several isotopes) were analyzed by inductively coupled plasma high resolution mass spectrometry (ICP-HRMS). Additionally, gross chemical composition (GCC) was analyzed. The 25 poultry breast filets samples originated from Switzerland, France, Germany, Hungary, Brazil, and Thailand, and the 23 dried beef samples, made from M. biceps femoris and M. semitendinosus, were produced in Switzerland, Austria, Australia, United States, and Canada out of raw meat originating either from these or from other countries. A total of 66 and 46 of the elements and isotopes followed were detected in beef and poultry, respectively. For statistical analyses, only the most abundant isotopes per element were used. For both poultry meat and dried beef, a differentiation of the origins was possible using those elements, which were significantly different across countries (As, Na, Rb, and Tl in poultry; B, Ca, Cd, Cu, Dy, Eu, Ga, Li, Ni, Pd, Rb, Sr, Te, Tl, Tm, V, Yb, and Zn in beef). No sufficient differentiation between origins was possible with GCC. Further studies have to confirm the suitability of this approach for meat authentication with more samples.     

Harnstoffhydrolyse für die selektive katalytische Reduktion von NOx: Vergleich der Flüssig‐ und Gasphasenzersetzung

In order to reduce the NO_x concentration in car exhausts usually the selective catalytic reduction with ammonia is used. However, to avoid the transport of ammonia in vehicles urea is applied as NH₃ precursor. Controlled urea decomposition before the injection into the exhaust gas system itself may be accomplished by the use of a separate reactor. Urea decomposition to ammonia in the liquid phase under pressure in a heated reactor was compared to its decomposition in the gas phase. In the liquid phase, higher conversion rates relative to the reactor volume were realized than in the gas phase. Catalysts which showed high activity in the gas phase influenced the decomposition in the liquid phase only slightly.     

Deformation-morphology correlations in electrically conductive carbon nanotube—thermoplastic polyurethane nanocomposites

Addition of small amounts (0.5-10 vol%) of multiwall carbon nanotubes (CNT) to thermoplastic elastomer Morthane produced polymer nanocomposites with high electrical conductivity (σ∼1-10 S/cm), low electrical percolation (?∼0.005) and enhancement of mechanical properties including increased modulus and yield stress without loss of the ability to stretch the elastomer above 1000% before rupture. In situ X-ray scattering during deformation indicated that these mechanical enhancements arise not only from the CNTs, but also from their impact on soft-segment crystallization. The deformation behavior after yielding of the nanocomposites, irrespective of CNT concentration, is similar to the unfilled elastomer, implying that the mechanistics of large deformation is mainly governed by the matrix. The relative enhancement of the Young's modulus of the nanocomposites is comparable to other elastomeric nanocomposites, implying that to the first order specific chemical details of the elastomeric system is unimportant.     

Response of real-time black carbon mass instruments to mini-CAST soot

Soot is a climate forcer and a dangerous air pollutant that has been increasingly regulated. In aviation, regulatory measurements of soot mass concentration in the exhaust of aircraft turbine engines are to be based on measurements of black carbon (BC) calibrated to elemental carbon (EC) content of diffusion flame soot. The calibration soot must currently meet only one criterion: minimum EC to total carbon (TC) ratio of 0.8. However, not including soot properties other than the EC/TC ratio may potentially lead to discrepancies between different BC measurements. We studied the response of two instruments, the AVL Micro-Soot Sensor (MSS) and the Artium Laser-Induced Incandescence 300 (LII), to soot from two miniature combustion aerosol standard (mini-CAST) burners. By changing the air-fuel ratio, premixing nitrogen into the fuel, and using a catalytic stripper to remove volatile compounds, we produced a wide range of particle morphologies and EC contents. As the EC content decreased, both the instruments underreported the EC mass, but the LII diverged more severely. Upon closer investigation of eight conditions with EC/TC > 0.8, the LII underreporting was found independent of primary particle size, but increased with decreasing geometric mean diameter of the soot agglomerates. As the geometric mean diameter decreased from 160 nm to 50 nm, the differences between the LII and MSS increased from 15% to 50%. The results suggest that in addition to EC content, calibration procedures for the regulatory BC measurements may need to take particle size distributions into account.

© 2016 American Association for Aerosol Research     

Large-scale production of bioactive ingredients as supplements for healthy human and animal nutrition

In this review, synthetic strategies and the development of environmentally benign methods for the production of economically important vitamins, carotenoids, and nutraceuticals used as food and feed supplements are illustrated by selected examples. The application of efficient catalytic transformations in multi-step chemical syntheses of such natural products enables technically feasible and cost-effective processes. For the preparation of fat-soluble (isoprenoid) vitamins A and E and the water-soluble vitamin (+)-biotin, homogeneous metal catalysis, including enantioselective transformations, heterogeneous and enzymatic catalysis serve as key methodologies. In the area of carotenoids, general building concepts and coupling methods for the total synthesis of beta-carotene and astaxanthin are discussed. Biotechnological methods and isolation from natural sources are also employed successfully, as exemplified for the xanthophyll lutein and the antioxidant (-)-epigallocatechin gallate. Lastly, key steps of the chemical synthesis of the polyphenol resveratrol are highlighted.     

Production of Furfural from Lignocellulosic Biomass Using Beta Zeolite and Biomass-Derived Solvent

The production of furfural from the C₅ monosaccharides xylose, arabinose and ribose, as well as from real biomass (corn fiber), was studied using H-Beta zeolite as catalyst in a monophasic system with the biomass-derived solvent, gamma-valerolactone. Due to the combination of Brønsted and Lewis acid sites on this catalyst (Brønsted:Lewis ratio = 1.66), H-Beta acts as a bifunctional catalyst, being able to isomerize (Lewis acid) and dehydrate (Brønsted acid) monosaccharides. The combination of Lewis and Brønsted acid functionality of H-Beta was shown to be effective for the isomerization of xylose and arabinose, followed by dehydration. While no advantages were found in the conversion of xylose, higher furfural yields were achieved from arabinose, using H-Beta, 73 %, compared to sulfuric acid (44 %) and Mordenite (49 %). The furfural yields from corn fiber for H-Beta, H-Mordenite and sulfuric acid were 62, 44, and 55 %, respectively, showing that H-Beta is particularly effective for conversion of this biomass feedstock composed of 45 wt% hemicellulose, of which 66 % is xylose and 33 % arabinose.