Hydrogen drainage from the pressurizer system

V tlakovodních reaktorech jaderných elektráren vzniká radiolýzou vody a také chemickými procesy v primárním médiu nežádoucí vodík, který je nutno z bezpečnostních důvodů z primárního okruhu odvádět řízeným způsobem. Systém odvodu vodíku dle projektu ŠJS slouží k oddělování a odvádění vodíku z paroplynné směsi ze systému kompenzace objemu jaderné elektrárny typu VVER a PWR. V tomto příspěvku je popsána historie vývoje tohoto systému v ČR a ve světě – a především je poprvé oficiálně představen tento systém odborné veřejnosti, a to u příležitosti konference v Srní.In pressurized water reactors of nuclear power plants, unwanted hydrogen is generated by radiolysis of water and also by chemical processes in the primary medium. For safety reasons, this undesirable hydrogen must be removed from the primary circuit in a controlled manner. The hydrogen removal system designed by ŠJS serves to separate and remove hydrogen from the steam-gas mixture in the volume compensation system of VVER and PWR nuclear power plants. This document describes the history of the development of this system in the Czech Republic and in the world – and above all, for the first time, this system is officially introduced to the professional public on the occasion of the conference in Srní

Two New Species of the Genus Stenamoeba Smirnov, Nassonova, Chao et Cavalier-Smith, 2007

As a result of light microscopical, ultrastructural and molecular study of three amoeba strains isolated from organs of three freshwater fish hosts, Stenamoeba amazonica sp. n. and S. limacina sp. n. are described as new amoeba species. The mutual comparison of isolated strains has extended the knowledge of morphological diversity within the genus Stenamoeba Smirnov, Nassonova, Chao et Cavalier-Smith, 2007. Molecular data obtained for these strains have complemented the phylogenetic tree that so far has contained only one nominal species within the single-genus Stenamoeba clade

Understanding Spatio-Temporal Usage Patterns of Cargo Bike Sharing to Foster Market Diffusion

Cargo bikes promote urban resilience as they ensure a local supply of goods, can be used flexibly, are reliable and require low energy, and can even be driven by muscle power. Further, they contribute to socially inclusive mobility. Although driving cargo bikes may require some training, they do not require a driving licence and can be available for different income ranges (e.g. in the form of cargo bike sharing). Thus, they also contribute to health-promoting mobility. Cargo bike sharing is a relevant solution to offer households a practical, environmentally friendly and cheaper mode of transport. According to public welfare-oriented goals, cargo bike sharing is often provided on behalf of, or with (financial) public sector support, in cooperation with residential developers or based on voluntary work in Austria and Germany. However, peer-to-peer cargo bike sharing offers and host-based sharing systems often do not meet all the criteria attributed to shared mobility services. In order to reach the full potential of cargo bike sharing, a better understanding of spatio-temporal usage patterns is needed to foster a shift towards higher quality service provision, especially regarding tailor-made services for different user groups. The following article investigates the role of availability and type of service provision by evaluating booking data and spatio-temporal data in three case studies. GPS tracking is rarely used to better understand cargo bike usage, but it reveals further knowledge of the characteristics of users and their spatial usage patterns. Based on three use cases, usage, users and spatial patterns of cargo bike sharing usage are analysed, the respective potentials are shown, and the added value of spatial data collection is discussed

Nationwide increases in anti-SARS-CoV-2 IgG antibodies between October 2020 and March 2021 in the unvaccinated Czech population

Background: The aim of the nationwide prospective seroconversion (PROSECO) study was to investigate the dynamics of anti-SARS-CoV-2 IgG antibodies in the Czech population. Here we report on baseline prevalence from that study. Methods: The study included the first 30,054 persons who provided a blood sample between October 2020 and March 2021. Seroprevalence was compared between calendar periods, previous RT-PCR results and other factors. Results: The data show a large increase in seropositivity over time, from 28% in October/November 2020 to 43% in December 2020/January 2021 to 51% in February/March 2021. These trends were consistent with government data on cumulative viral antigenic prevalence in the population captured by PCR testing – although the seroprevalence rates established in this study were considerably higher. There were only minor differences in seropositivity between sexes, age groups and BMI categories, and results were similar between test providing laboratories. Seropositivity was substantially higher among persons with history of symptoms (76% vs. 34%). At least one third of all seropositive participants had no history of symptoms, and 28% of participants with antibodies against SARS-CoV-2 never underwent PCR testing. Conclusions: Our data confirm the rapidly increasing prevalence in the Czech population during the rising pandemic wave prior to the beginning of vaccination. The difference between our results on seroprevalence and PCR testing suggests that antibody response provides a better marker of past infection than the routine testing program

Sound Transmission Loss of a Sandwich Plate with Adjustable Core Layer Thickness

Compressible Constrained Layer Damping (CCLD) is a novel, semi-active, lightweightcompatible solution for vibration mitigation based on the well-known constrained layer damping principle. The sandwich-like CCLD set-up consists of a base structure, a constraining plate, and a compressible open-cell foam core in between, enabling the adjustment of the structure’s vibration behaviour by changing the core compression using different actuation pressures. The aim of the contribution is to show to what degree, and in which frequency range the acoustic behaviour can be tuned using CCLD. Therefore, the sound transmission loss (TL), as an important vibro-acoustic index, is determined in an acoustic window test stand at different actuation pressures covering a frequency range from 0.5 to 5 kHz. The different actuation pressures applied cause a variation of the core layer thickness (from 0.9 d₀ to 0.3 d₀), but the resulting changes of the stiffness and damping of the overall structure have no significant influence on the TL up to approximately 1 kHz for the analysed CCLD design. Between 1 kHz and 5 kHz, however, the TL can be influenced considerably well by the actuation pressure applied, due to a damping-dominated behaviour around the critical frequenc

Effects of sodium nitrite reduction, removal or replacement on cured and cooked meat for microbiological growth, food safety, colon ecosystem, and colorectal carcinogenesis in Fischer 344 rats

Epidemiological and experimental evidence indicated that processed meat consumption is associated with colorectal cancer risks. Several studies suggest the involvement of nitrite or nitrate additives via N-nitroso-compound formation (NOCs). Compared to the reference level (120 mg/kg of ham), sodium nitrite removal and reduction (90 mg/kg) similarly decreased preneoplastic lesions in F344 rats, but only reduction had an inhibitory effect on Listeria monocytogenes growth comparable to that obtained using the reference nitrite level and an effective lipid peroxidation control. Among the three nitrite salt alternatives tested, none of them led to a significant gain when compared to the reference level: vegetable stock, due to nitrate presence, was very similar to this reference nitrite level, yeast extract induced a strong luminal peroxidation and no decrease in preneoplastic lesions in rats despite the absence of NOCs, and polyphenol rich extract induced the clearest downward trend on preneoplastic lesions in rats but the concomitant presence of nitrosyl iron in feces. Except the vegetable stock, other alternatives were less efficient than sodium nitrite in reducing L. monocytogenes growth

Dynamic changes in genomic and social structures in third millennium BCE central Europe

Europe’s prehistory oversaw dynamic and complex interactions of diverse societies, hitherto unexplored at detailed regional scales. Studying 271 human genomes dated ~4900 to 1600 BCE from the European heartland, Bohemia, we reveal unprecedented genetic changes and social processes. Major migrations preceded the arrival of “steppe” ancestry, and at ~2800 BCE, three genetically and culturally differentiated groups coexisted. Corded Ware appeared by 2900 BCE, were initially genetically diverse, did not derive all steppe ancestry from known Yamnaya, and assimilated females of diverse backgrounds. Both Corded Ware and Bell Beaker groups underwent dynamic changes, involving sharp reductions and complete replacements of Y-chromosomal diversity at ~2600 and ~2400 BCE, respectively, the latter accompanied by increased Neolithic-like ancestry. The Bronze Age saw new social organization emerge amid a ≥40% population turnover.Peer reviewe

Differential (2+1) Jet Event Rates and Determination of alpha_s in Deep Inelastic Scattering at HERA

Events with a (2+1) jet topology in deep-inelastic scattering at HERA are studied in the kinematic range 200 < Q^2< 10,000 GeV^2. The rate of (2+1) jet events has been determined with the modified JADE jet algorithm as a function of the jet resolution parameter and is compared with the predictions of Monte Carlo models. In addition, the event rate is corrected for both hadronization and detector effects and is compared with next-to-leading order QCD calculations. A value of the strong coupling constant of alpha_s(M_Z^2)= 0.118+- 0.002 (stat.)^(+0.007)_(-0.008) (syst.)^(+0.007)_(-0.006) (theory) is extracted. The systematic error includes uncertainties in the calorimeter energy calibration, in the description of the data by current Monte Carlo models, and in the knowledge of the parton densities. The theoretical error is dominated by the renormalization scale ambiguity.Comment: 25 pages, 6 figures, 3 tables, submitted to Eur. Phys.

Hadron Production in Diffractive Deep-Inelastic Scattering

Characteristics of hadron production in diffractive deep-inelastic positron-proton scattering are studied using data collected in 1994 by the H1 experiment at HERA. The following distributions are measured in the centre-of-mass frame of the photon dissociation system: the hadronic energy flow, the Feynman-x (x_F) variable for charged particles, the squared transverse momentum of charged particles (p_T^{*2}), and the mean p_T^{*2} as a function of x_F. These distributions are compared with results in the gamma^* p centre-of-mass frame from inclusive deep-inelastic scattering in the fixed-target experiment EMC, and also with the predictions of several Monte Carlo calculations. The data are consistent with a picture in which the partonic structure of the diffractive exchange is dominated at low Q^2 by hard gluons.Comment: 16 pages, 6 figures, submitted to Phys. Lett.