An experimental evaluation of the transmission of shock waves from a detonating gas mixture in a 0.5-in-inner-diameter open-ended tube into an inert atmosphere is described in this paper. ...Stoichiometric H
2
/O
2
at 1 atm was used as the reactive gas medium. Results from in-tube diagnostics indicated successful deflagration-to-detonation transition (DDT), which leads to an overdriven detonation before exiting the tube at near Chapman–Jouguet (CJ) conditions. Out-of-tube diagnostics characterized the transmission of the shock wave into the surrounding environment, where the shock wave decays into an acoustic wave as it travels away from the tube exit. A mathematical treatment of overpressure and time-of-arrival data allowed for a direct analytical description of the transmitted shock wave’s transient velocity. This description is combined with a first-principles gas-dynamics treatment of the moving normal shock wave to describe the conditions behind the attenuating shock wave. This work furthers the understanding of shock transmission from an open-ended detonation tube and provides a theoretical framework to estimate the resulting conditions.
The KArlsruhe TRItium Neutrino experiment (KATRIN) aims to determine the effective electron (anti)-neutrino mass with a sensitivity of 0.2eV/c \(^2\) by precisely measuring the endpoint region of the ...tritium \(\beta \) -decay spectrum. It uses a tandem of electrostatic spectrometers working as magnetic adiabatic collimation combined with an electrostatic (MAC-E) filters. In the space between the pre-spectrometer and the main spectrometer, creating a Penning trap is unavoidable when the superconducting magnet between the two spectrometers, biased at their respective nominal potentials, is energized. The electrons accumulated in this trap can lead to discharges, which create additional background electrons and endanger the spectrometer and detector section downstream. To counteract this problem, “electron catchers” were installed in the beamline inside the magnet bore between the two spectrometers. These catchers can be moved across the magnetic-flux tube and intercept on a sub-ms time scale the stored electrons along their magnetron motion paths. In this paper, we report on the design and the successful commissioning of the electron catchers and present results on their efficiency in reducing the experimental background.
The trigger system for the AUGER fluorescence detector is presented. The main goals of the design were low price, high flexibility of the trigger, high reliability and good testability even at remote ...operation. The simulation of all boards using VHDL tools resulted in a design which is optimal with respect to these goals and highly independent of existing commercial solutions. The large-scale integration of modern FPGAs yielded a massive parallel system for recognition of tracks and suppression of background. The readout and control is carried out by low cost PCs under the LINUX operating system.
The KATRIN experiment is designed for a direct and model-independent determination of the effective electron anti-neutrino mass via a high-precision measurement of the tritium \(\beta\)-decay ...endpoint region with a sensitivity on \(m_\nu\) of 0.2\(\,\)eV/c\(^2\) (90% CL). For this purpose, the \(\beta\)-electrons from a high-luminosity windowless gaseous tritium source traversing an electrostatic retarding spectrometer are counted to obtain an integral spectrum around the endpoint energy of 18.6\(\,\)keV. A dominant systematic effect of the response of the experimental setup is the energy loss of \(\beta\)-electrons from elastic and inelastic scattering off tritium molecules within the source. We determined the \linebreak energy-loss function in-situ with a pulsed angular-selective and monoenergetic photoelectron source at various tritium-source densities. The data was recorded in integral and differential modes; the latter was achieved by using a novel time-of-flight technique. We developed a semi-empirical parametrization for the energy-loss function for the scattering of 18.6-keV electrons from hydrogen isotopologs. This model was fit to measurement data with a 95% T\(_2\) gas mixture at 30\(\,\)K, as used in the first KATRIN neutrino mass analyses, as well as a D\(_2\) gas mixture of 96% purity used in KATRIN commissioning runs. The achieved precision on the energy-loss function has abated the corresponding uncertainty of \(\sigma(m_\nu^2)<10^{-2}\,\mathrm{eV}^2\) arXiv:2101.05253 in the KATRIN neutrino-mass measurement to a subdominant level.
The KArlsruhe TRItium Neutrino experiment (KATRIN) aims to determine the effective electron (anti)neutrino mass with a sensitivity of \(0.2\textrm{ eV/c}^2\) (90\(\%\) C.L.) by precisely measuring ...the endpoint region of the tritium \(\beta\)-decay spectrum. It uses a tandem of electrostatic spectrometers working as MAC-E (magnetic adiabatic collimation combined with an electrostatic) filters. In the space between the pre-spectrometer and the main spectrometer, an unavoidable Penning trap is created when the superconducting magnet between the two spectrometers, biased at their respective nominal potentials, is energized. The electrons accumulated in this trap can lead to discharges, which create additional background electrons and endanger the spectrometer and detector section downstream. To counteract this problem, "electron catchers" were installed in the beamline inside the magnet bore between the two spectrometers. These catchers can be moved across the magnetic-flux tube and intercept on a sub-ms time scale the stored electrons along their magnetron motion paths. In this paper, we report on the design and the successful commissioning of the electron catchers and present results on their efficiency in reducing the experimental background.
Escherichia coli K-12 W3110 grows in the presence of membrane-permeant organic acids that can depress cytoplasmic pH and accumulate in the cytoplasm. We conducted experimental evolution by daily ...diluting cultures in increasing concentrations of benzoic acid (up to 20 mM) buffered at external pH 6.5, a pH at which permeant acids concentrate in the cytoplasm. By 2,000 generations, clones isolated from evolving populations showed increasing tolerance to benzoate but were sensitive to chloramphenicol and tetracycline. Sixteen clones grew to stationary phase in 20 mM benzoate, whereas the ancestral strain W3110 peaked and declined. Similar growth occurred in 10 mM salicylate. Benzoate-evolved strains grew like W3110 in the absence of benzoate, in media buffered at pH 4.8, pH 7.0, or pH 9.0, or in 20 mM acetate or sorbate at pH 6.5. Genomes of 16 strains revealed over 100 mutations, including single-nucleotide polymorphisms (SNPs), large deletions, and insertion knockouts. Most strains acquired deletions in the benzoate-induced multiple antibiotic resistance (Mar) regulon or in associated regulators such as rob and cpxA, as well as the multidrug resistance (MDR) efflux pumps emrA, emrY, and mdtA Strains also lost or downregulated the Gad acid fitness regulon. In 5 mM benzoate or in 2 mM salicylate (2-hydroxybenzoate), most strains showed increased sensitivity to the antibiotics chloramphenicol and tetracycline; some strains were more sensitive than a marA knockout strain. Thus, our benzoate-evolved strains may reveal additional unknown drug resistance components. Benzoate or salicylate selection pressure may cause general loss of MDR genes and regulators.
Benzoate is a common food preservative, and salicylate is the primary active metabolite of aspirin. In the gut microbiome, genetic adaptation to salicylate may involve loss or downregulation of inducible multidrug resistance systems. This discovery implies that aspirin therapy may modulate the human gut microbiome to favor salicylate tolerance at the expense of drug resistance. Similar aspirin-associated loss of drug resistance might occur in bacterial pathogens found in arterial plaques.
Only a few studies have been conducted in which regenerability of barley has been examined. In the current study, 17 barley genotypes (nine two-row malting type: Aster, Emon, Ruen, Jubiley, PV101, ...Korten, Krassi 2, Perun and Igri, and eight six-row feed types: Karnobat, Hemus, Jerun, Veslets, Aheloi 2, Diana, Panagon, and Izrgev) were evaluated for tissue-culture response from seedlings during a three-year period. Regenerable calli were obtained from all tested genotypes. Although there was much variation in regeneration capacity among the cultivars, plants were obtained from all cultivars. The majority of green plants grown to maturity were fertile and normal in appearance. The frequency of embryogenic callus induction and regenerability was influenced by genotype and growth conditions of the donor plants. Genotype was the most important determinant of the in vitro response. The best in vitro performance, based on ability to form regenerable calli and to regenerate plants was observed for Ruen, Aster, and Emon.
Two 200 mg quinidine sulfate tablets were administered to nine healthy male subjects in the fasting state, immediately after a balanced meal, and with 30 ml of aluminum hydroxide gel using a complete ...crossover design. Serum and urine samples were taken over 32 and 60 h, respectively. Quinidine concentrations were measured using a high-performance liquid chromatography assay specific for quinidine. Computer fitting of the data to several models indicated that a one-compartment model with zero-order absorption and a lag time best fit all the data. Quinidine elimination and urine pH were unaffected by the study conditions. While the maximum serum concentration (Cmax) and area under the serum concentration-time curve (AUC) were unaffected by administration of quinidine with food or antacid, there was a 44 per cent increase (p less than 0.10) in time to Cmax (tmax) following quinidine administration with food. Thus, while the extent of quinidine absorption was unaffected by food or the antacid used, the rate of quinidine absorption was significantly reduced by food as reported earlier.
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