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Areli Burgueño‑Roman,Gloria M. Castañeda‑Ruelas,Ramón Pacheco‑Arjona,Maribel Jimenez‑Edeza 한국유전학회 2019 Genes & Genomics Vol.41 No.7
Background River water has been implicated as a source of non-typhoidal Salmonella (NTS) serovars in Mexico. Objective To dissect the molecular pathogenesis and defense strategies of seven NTS strains isolated from river water in Mexico. Methods The genome of Salmonella serovars Give, Pomona, Kedougou, Stanley, Oranienburg, Sandiego, and Muenchen were sequenced using the whole-genome shotgun methodology in the Illumina Miseq platform. The genoma annotation and evolutionary analyses were conducted in the RAST and FigTree servers, respectively. The MLST was performed using the SRST2 tool and the comparisons between strains were clustered and visualized using the Gview server. Experimental virulence assay was included to evaluate the pathogenic potential of strains. Results We report seven high-quality draft genomes, ranging from ~ 4.61 to ~ 5.12 Mb, with a median G + C value, coding DNA sequence, and protein values of 52.1%, 4697 bp, and 4,589 bp, respectively. The NTS serovars presented with an open pan-genome, offering novel genetic content. Each NTS serovar had an indistinguishable virulotype with a core genome (352 virulence genes) closely associated with Salmonella pathogenicity; 13 genes were characterized as serotype specific, which could explain differences in pathogenicity. All strains maintained highly conserved genetic content regarding the Salmonella pathogenicity islands (1–5) (86.9–100%), fimbriae (84.6%), and hypermutation (100%) genes. Adherence and invasion capacity were confirmed among NTS strains in Caco-2 cells. Conclusion Our results demonstrated the arsenal of virulence and defense molecular factors harbored on NTS serovars and highlight that environmental NTS strains are waterborne pathogens worthy of attention.
Grain Size Dependent Bandgap Shift of SnO2 Nanofibers
Roman Viter,Akash Katoch,Sang-Sub Kim 대한금속·재료학회 2014 METALS AND MATERIALS International Vol.20 No.1
SnO2 nanofibers with various grain sizes ranging from 18.5 to 31.6 nm in diameter were fabricated byelectrospinning a polymeric solution and subsequent controlled calcination of the as-spun fibers. The cal-cined fibers were polycrystalline and composed of densely packed nano-sized SnO2 grains. The effect ofthe nanograin size on the optical bandgap of SnO2 nanofibers was examined by ultraviolet-visible spec-troscopy. The bandgap showed a strong dependence on the nanograin size. The bandgap decreased withincreasing nanograin size. Some calculations were performed to understand the relationship between theexperimentally obtained bandgaps of the SnO2 nanofibers and the theoretical ones. Quantum confinementand lattice strain of the SnO2 nanofibers are likely responsible for the bandgap shift. This suggests thatoptimization of the nanograin size is essential not only for achieving the required optical properties ofoxide nanofibers, but also to secure superior working properties of electronic devices that are fabricatedwith electrospinning-synthesized oxide nanofibers.
Roman M. Janas,Anna Rybak,Aldona Wierzbicka-Rucińska,Piotr Socha,Rafał Śnitko,Anna Szaflarska-Popławska,Anna Stolarczyk,Beata Oralewska,Elżbieta Cytra-Jarocka,Barbara Iwańczak,Urszula Grzybowska-Chleb 거트앤리버 소화기연관학회협의회 2016 Gut and Liver Vol.10 No.4
Background/Aims: The roles of the many bioactive peptides in the pathogenesis of celiac disease remain unclear. To evaluate the serum concentrations of insulin, ghrelin, adiponectin, leptin, leptin receptor, and lipocalin-2 in children with celiac disease who do and do not adhere to a gluten-free diet (GFD, intermittent adherence). Methods: Prepubertal, pubertal, and adolescent celiac children were included in this study (74 girls and 53 boys on a GFD and 80 girls and 40 boys off of a GFD). Results: Insulin levels in prepubertal (9.01±4.43 μIU/mL), pubertal (10.3±3.62 μIU/mL), and adolescent (10.8±4.73 μIU/mL) girls were higher than those in boys (5.88±2.02, 8.81±2.88, and 8.81±2.26 μIU/mL, respectively) and were neither age-dependent nor influenced by a GFD. Prepubertal children off of a GFD exhibited higher ghrelin levels than prepubertal children on a GFD. Adiponectin levels were not age-, sex- nor GFD-dependent. Adherence to a GFD had no effect on the expression of leptin, leptin receptor, and lipocalin-2. Conclusions: Adherence to a GFD had no influence on the adiponectin, leptin, leptin receptor, and lipocalin-2 concentrations in celiac children, but a GFD decreased highly elevated ghrelin levels in prepubertal children. Further studies are required to determine whether increased insulin concentrations in girls with celiac disease is suggestive of an increased risk for hyperinsulinemia.
Parameters identification of fractional models of viscoelastic dampers and fluids
Roman Lewandowski,Mieczyslaw Slowik,Maciej Przychodzki 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.63 No.2
An identification method for determination of the parameters of the rheological models of dampers made of viscoelastic material is presented. The models have two, three or four parameters and the model equations of motion contain derivatives of the fractional order. The results of dynamical experiments are approximated using the trigonometric function in the first part of the procedure while the model parameters are determined as the solution to an appropriately defined optimization problem. The particle swarm optimization method is used to solve the optimization problem. The validity and effectiveness of the suggested identification method have been tested using artificial data and a set of real experimental data describing the dynamic behavior of damper and a fluid frequently used in dampers. The influence of a range of excitation frequencies used in experiments on results of identification is also discussed.
Fatigue Life Prediction for Distortion-Induced Cracking of Steel Bridges
Roman Okelo 한국강구조학회 2017 International Journal of Steel Structures Vol.17 No.2
Fatigue is the main reason for the limited service life of welded plate girders built before the mid-1970s. Although, current bridge design specifications provide estimates of fatigue life for load-induced cases, fatigue cracking due to out-of-plane distortion is not adequately addressed, despite its severity. This paper presents a three-dimensional (3D) finite element analysis (FEA) of two units of the I-345 Bridge using the commercially available software LUSAS. The modeling procedure is used to determine the magnitude of the distortion-induced stresses, the fatigue life, and the effectiveness of the retrofit strategies. The results in terms of contour plots for the as-built and repaired connections show a high stress concentration at crack initiation sites, in agreement with the bridge inspection reports. The used retrofits methods, when properly carried out, provide a full restoration of the service life of the connections. A relationship is proposed to predict the fatigue life for distortion-induced cracking.
Roman Mukin,Ivor Clifford,Omar Zerkak,Hakim Ferroukhi 한국원자력학회 2018 Nuclear Engineering and Technology Vol.50 No.3
A series of tests dedicated to station blackout (SBO) accident scenarios have been recently performed at thePrim€arkreislauf-Versuchsanlage (primary coolant loop test facility; PKL) facility in the framework of theOECD/NEAPKL-3 project. These investigations address current safety issues related to beyond design basis accidenttransients with significant core heat up. This work presents a detailed analysis using the best estimatethermalehydraulic code TRACE (v5.0 Patch4) of different SBO scenarios conducted at the PKL facility; failuresof high- and low-pressure safety injection systems together with steam generator (SG) feedwatersupply are considered, thus calling for adequate accidentmanagement actions and timelyimplementation ofalternative emergency cooling procedures to prevent core meltdown. The presented analysis evaluates thecapability of the applied TRACE model of the PKL facility to correctly capture the sequences of events in thedifferent SBO scenarios, namely the SBO tests H2.1, H2.2 run 1 and H2.2 run 2, including symmetric orasymmetric secondary side depressurization, primary side depressurization, accumulator (ACC) injection inthe cold legs and secondary side feeding with mobile pump and/or primary side emergency core coolantinjection from the fuel pool cooling pump. This study is focused specifically on the prediction of the core exittemperature, which drives the execution of the most relevant accident management actions. This workpresents, in particular, the key improvements made to the TRACE model that helped to improve the codepredictions, including the modeling of dynamical heat losses, the nodalization of SGs' heat exchanger tubesand theACCs. Another relevant aspect of thiswork is to evaluate howwell themodel simulations of the threedifferent scenarios qualitatively and quantitatively capture the trends and results exhibited by the actualexperiments. For instance, howthenumber of SGs considered for secondary side depressurization affects theheat transfer from primary side; how the discharge capacity of the pressurizer relief valve affects the dynamicsof the transient; how ACC initial pressure and nitrogen release affect the grace time between ACCinjection and subsequent core heat up; and howwell the alternative feeding modes of the secondary and/orprimary side with mobile injection pumps affect core quenching and ensure stable long-term core coolingunder controlled boiling conditions.