Experimental and numerical study on the detection of fatigue failure in hydraulic turbines

Xavier Sánchez-Botello,Adolfo de la Torre,Rafel Roig,Esteve Jou,Oscar de la Torre,Javier Ayneto,Xavier Escaler 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.10

Detecting fatigue cracks in hydraulic turbine runners is costly, as it requires stopping the unit, emptying it of water and accessing the runner for inspection. Thus, an alternative way based on monitoring the changes of the structural modal response induced by the formation and growth of a crack was investigated. To do so, the crack propagation induced by a resonance was numerically predicted and experimentally machined on a disk-like structure that resembles a Kaplan turbine runner. The analysis of the results shows how the different stages of the fatigue crack growth can be monitored based on the change of the natural frequencies and mode shapes of several specific modes. Based on the obtained results, a structural health monitoring system is being designed to monitor the turbine runner modes of vibration without the need to stop and inspect the unit.

Experimental and numerical study of turbulent mixing in a model of a polymerization reactor

Xavier Ingle`s,Jordi Pallares,Marı´a Teresa Larre,Luis Me´ndez,Francesc Xavier Grau 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.4

In this study the turbulent mixing in a model of a polymerization reactor is analyzed experimentally and numerically. The model corresponds to a zone of an autoclave reactor equipped with a stirrer. Two different configurations of the stirrer, with different arrangement of the paddles, have been considered. The mixing process has been monitored by following the time-evolution of injections of a passive scalar through the different inlets of the model. The time-evolution of the mixing quality in a laboratory scale model of the reactor has been measured using water and the Planar Laser Induced Fluorescence (PLIF)technique. Numerical simulations of the flow and of the mixing processes were carried out and results of the evolution of the mixing are compared successfully with measurements. The mixing processes are dominated by the flow topology generated by the rotation of the stirrer. Superimposed to the tangential flow, secondary flows divide the length of the reactor in different zones. It has been found that macro mixing in each individual zone is a relatively fast process and that the mixing rates within each zone are very similar. However, the mixing rate between different zones is a relatively slow process.

The letter of François-Xavier Dumortier S.J.

François-Xavier Dumortier 서강대학교 서강대학교 신학연구소 2016 신학과 철학 Vol.- No.29

The letter of Francois-Xavier Dumortier S.J.

Francois-Xavier Dumortier S.J.(프랑수아-하비에르 뒤모르티에르 S.J.) 서강대학교 신학연구소 2016 신학과 철학 Vol.- No.29

Sensitive and selective turn-off-on fluorescence detection of Hg²⁺ and cysteine using nitrogen doped carbon nanodots derived from citron and urine

Xavier, S. Stanly John,Siva, G.,Annaraj, J.,Kim, Ae Rhan,Yoo, Dong Jin,kumar, G. Gnana Elsevier 2018 Sensors and actuators. B Chemical Vol.259 No.-

<P><B>Abstract</B></P> <P>An environmentally benign and cost efficient cysteine fluorescence sensor is constructed on the basis of nitrogen doped carbon nanodots (NCNDs) prepared by using citron fruit extract and human urine waste as carbon and nitrogen sources, respectively. The turn-off-on fluorescence technique is exploited for the sensing of cysteine, in which the initial fluorescence of NCNDs is quenched with Hg<SUP>2+</SUP> <I>via</I> an electron transfer process. Owing to the competitive binding of Hg<SUP>2+</SUP> with cysteine, the ‘turn-off’ fluorescence sensor is switched to the ‘turn-on’ state. Under optimized conditions, NCNDs-Hg<SUP>2+</SUP> assembly demonstrates a lower detection limit and a wide linear range toward cysteine detection. Furthermore, NCNDs display the discriminative detection of cysteine from the similar bioactive molecules and the co-existence of interference species does not influence the detection of NCNDs toward the interest of an analyte. Furthermore, the practical application of NCNDs based fluorescence sensor is validated with the good recovery in human urine samples, which explores the new avenues in the fluorescence sensing of biomolecules.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Environmentally benign NCNDs are prepared from citron and human urine. </LI> <LI> Turn-off-on fluorescence technique is exploited for the cysteine sensing. </LI> <LI> Fluorescence behavior of NCNDs is quenched with Hg<SUP>2+</SUP> and is regenerated with cysteine. </LI> <LI> NCNDs exhibit rapid fluorometric response with a LOD of 40 nM toward cysteine. </LI> <LI> NCNDs demonstrate selective cysteine detection and real sample analysis. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Radiological anatomy of the thoracic outlet and imaging assessment of a thoracic outlet syndrome

Xavier DEMONDION 대한체질인류학회 2007 대한체질인류학회 학술대회 연제 초록 Vol.50 No.-

Toxicity of TiO2 nanoparticles on the NRK52E renal cell line

Xavier Valentini,Lara Absil,Guy Laurent,Alexandre Robbe,Sophie Laurent,Robert Muller,Alexandre Legrand,Denis Nonclercq 대한독성 유전단백체 학회 2017 Molecular & cellular toxicology Vol.13 No.4

Titanium dioxide nanoparticles are widely used in industry to produce a number of products (cosmetics, paints, foods). TiO2 nanoparticles form aggregates and their toxicity varies in function of their size. In this study, aggregate sizes were determined using dynamic light scattering (DLS). The stability of the suspension was evaluated by turbidimetry and the size by transmission electronic microscopy (TEM). In the present study the toxicity of TiO2 nanoparticles was evaluated in vitro on rat kidney proximal tubular cells(NRK-52E). Cells were exposed to TiO2 nanoparticles (20 μg/mL) for 24, 48, 72 and 96 hours. TiO2 nanoparticles induce the production of reactive oxygen species(ROS). The relative number of mitosis decreased, while an increase of apoptotic cells was noted. The number of S-phase cells evidenced by BrdU immunoreactivity in cultures was significantly reduced by the exposure to the nanoparticles. These results attest to the toxic effect of the TiO2 nanoparticles on NRK-52E cells.

Clozapine in the Time of COVID-19

Xavier Boland,Luiz Dratcu 대한정신약물학회 2020 CLINICAL PSYCHOPHARMACOLOGY AND NEUROSCIENCE Vol.18 No.3

Clozapine is the most effective antipsychotic for treatment resistant schizophrenia but adverse reactions to clozapine include neutropenia. The current COVID-19 pandemic may raise specific concerns for clinicians prescribing clozapine for patients who need it. We report on two actively psychotic patients with treatment resistant schizophrenia who required admission to our inner-London acute psychiatric unit during the COVID-19 pandemic and who were treated with clozapine. One was a young patient who developed COVID-19 symptoms and tested positive for the SARS-CoV-2 virus while receiving clozapine and the other was an aging man who tested negative for the SARS-CoV-2 virus but had contact with COVID-19 during initiation of clozapine treatment. Both responded to clozapine treatment and were safely discharged from hospital without any complication. These cases suggest that, in the absence of complications, exposure to COVID-19 per se and the onset of mild symptoms in those infected may not warrant withdrawal or postponement of clozapine treatment when this is indicated.

Unacceptable but Indispensable: Opium Law and Regulations in Guangdong, 1912-1936

Xavier Paulès 고려대학교 민족문화연구원 2013 Cross-Currents Vol.- No.7

During most of the period from 1912 to 1936, Guangdong Province was independent from the central government. The local authorities there were facing a dilemma regarding opium, as others were elsewhere in China. On the one hand, opium was considered the symbol of China’s weakness, and its suppression was a top priority; on the other hand, opium taxes represented an indispensable source of fiscal income. Some Guangdong power holders were truly committed to a suppression agenda, especially from 1913 to 1924. During this period, with the exception of a brief interlude from 1915 to 1916, opium laws were prohibition laws. Even if these laws were not always enforced with full vigor, the drug remained illegal in Guangdong. After 1924, opium was legalized, and the authorities openly ruled an opium monopoly. They came out with increasingly comprehensive regulations, which proved successful in increasing opium revenues. Yet, as this article makes clear, there was nothing like direct government control: traditional tax-farming arrangements with local opium merchants (though under stricter supervision) remained the backbone of the monopoly. The article also pays attention to the influence of the Six-Year Plan (1935–1940) launched by the Nanking government. As a credible set of suppression laws, it appealed to the Guangdong progressive elites who were hostile to opium. They urged the local autocrat Chen Jitang to take similar action. Chen made attempts to launch his own plans for suppressing opium, but they were unconvincing and nothing concrete came out of them. This article suggests that, in order to obtain a better understanding of how easily Chen Jitang was driven out of power in the summer of 1936, it is necessary to take into account the significant contribution of the Six-Year Plan in undermining his legitimacy.

Growth of 2D-layered double hydroxide nanorods heterojunction with 2D tungsten carbide nanocomposite: Improving the electrochemical sensing of norfloxacin

Xavier Benadict Joseph,Megha Maria Stanley,Sea-Fue Wang,Mary George 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.110 No.-

The potential impact of antibiotics in water environments affects aquatic organisms, microbial communitystructure, and resistance genes. In this work, we report the hydrothermal synthesis of twodimensional(2D) tungsten carbide (WC) nanoparticles on CO32- anion intercalated three-dimensional(3D) self-assembled nickel–cobalt layered double hydroxide (NiCo-LDH) nanorods, for the electrochemicaldetermination of norfloxacin (NRF). The synergistic impact between the dual active components ofthe prepared electrode offered increased active surface area, high electrical conductivity, and promptmass and ion diffusion, resulting in improved electrochemical performance for NRF monitoring. In idealconditions, WC@NiCo-LDH modified electrode exhibited enhanced electrochemical characteristics, widelinear response (DPV = 0.02–83.4 lM and in i-t = 0.002–346 lM), and lowdetection limit (LOD) (DPV = 0. 005 lM and i-t = 0.002 lM). Furthermore, good reproducibility, virtuous operational and cycle stabilities,were obtained. The practical applications in real-world samples with acceptable recovery ranges wereverified the interference-free sensing of NRF.