Phénomène d'instabilité paramétrique dans la réponse RF d'une antenne immergée dans un plasma

Plasma -- Gaine ionique -- Ondes de gaine -- Instabilités paramétriques -- Hypothèses de travail -- Expérimentation -- Système antenne-plasma -- Montage de mesure RF -- Résultats expérimentaux -- Résonances des ondes de gaine -- Instabilités paramétriques -- Étude de simulation -- Modélisation du système antenne-gaine-plasma -- Simulation analogique -- Simulation numérique -- Discussion -- Sur les résonances de gaine -- Sur l'instabilité paramétrique -- Sur la modélisation

Spatiotemporal evolution of SARS-CoV-2 Alpha and Delta variants during large nationwide outbreak of COVID-19, Vietnam, 2021

We analyzed 1,303 SARS-CoV-2 whole-genome sequences from Vietnam, and found the Alpha and Delta variants were responsible for a large nationwide outbreak of COVID-19 in 2021. The Delta variant was confined to the AY.57 lineage and caused >1.7 million infections and >32,000 deaths. Viral transmission was strongly affected by nonpharmaceutical interventions

Pilotażowe oczyszczanie wód powierzchniowych z wykorzystaniem technologii mikrohydraulicznej łączącej ozon i węgiel aktywny

The technological line proposed in the research process is a combination of Micro Hydraulic reaction technology combined with Ozone and activated carbon filtration. The processing line will be simulated by a test model with a capacity of 5 cubic meters per hour. Installation location at Nhi Thanh Water Supply Plant, Long An Province. The Pilot will operate in 9 different stages, in order to comprehensively evaluate the Pilot. The results of water quality analysis after the operation showed that the DO index increased from 3ppm to 7ppm, the pH remained stable at 7, turbidity (NTU) after treatment is always very low and averages at 0.01 NTU, Permanganate index after treatment is lower than 2 mg/l, average iron content is 0.05 mg/l, average manganese content is lower than 0.2 mg/l. Most of the water quality indicators are within the allowable limits according to QCVN 01-1: 2018/BYT, National technical regulation on Domestic Water Quality. This result will be compared with the quality of clean water after treatment at the Nhi Thanh water supply plant. Thereby, we can see the advantages and disadvantages when comparing the two water treatment technologies.Zaproponowana w procesie badawczym linia technologiczna jest połączeniem technologii reakcji Micro Hydraulic połączonej z filtracją ozonem i węglem aktywnym. Linia technologiczna będzie symulowana przez model testowy o wydajności 5 metrów sześciennych na godzinę. Miejsce instalacji w zakładzie wodociągowym Nhi Thanh w prowincji Long An. Instalacja pilotażowa będzie działała w 9 różnych etapach. Wyniki analizy jakości wody po procesie wykazały, że wskaźnik DO wzrósł z 3 ppm do 7 ppm, pH utrzymywało się na stabilnym poziomie 7, mętność (NTU) po uzdatnianiu jest zawsze bardzo niska i średnio 0,01 NTU, wskaźnik nadmanganianowy po uzdatnianiu jest niższy niż 2 mg/l, średnia zawartość żelaza wynosi 0,05 mg/l, średnia zawartość manganu jest niższa niż 0,2 mg/l. Większość wskaźników jakości wody mieści się w dopuszczalnych granicach zgodnie z QCVN 01-1: 2018/BYT, krajowymi przepisami technicznymi dotyczącymi jakości wody użytkowej. Wynik ten został porównany z jakością czystej wody po uzdatnieniu w wodociągu Nhi Thanh. W ten sposób pokazano zalety i wady dwóch technologii uzdatniania wody

Synthesis and photoresponse of PbBiSrCaCuO films

Thin films of PbBiSrCaCuO superconductor have been produced by means of single target magnetron rf sputtering followed by a heat treatment. The effects of deposition and post-annealing parameters on film properties were investigated. It was found that film thickness decreases near the discharge center, possibly due to the preferential ion bombardment of the film during deposition. Superconducting films with the high Tc 2223 phase could be obtained after a heat treatment as short as 60 min. A structural transition from the semiconducting phase to the low T c 2212 phase took place in the film during the preannealing in O 2 (20 min). During the subsequent annealing in air (40 min), a gradual structural transition from the 2212 phase to 2223 phase occurred when the annealing temperature and duration were increased. The resulting films showed Tc ~ 107 K and Jc exceeding 8 x 103 A/cm2 at 79 K. For all stages of the transition, the phases revealed in the temperature characteristics of electrical resistance and magnetic susceptibility are consistent with those identified in the XRD spectra of the film. Heat treatments of shorter duration or at lower temperatures resulted in films with mixed 2212 and 2223 phases, in which a superconducting percolation path could still be established at temperatures as high as 100 K. The evolution of film compositions with annealing time suggested that Pb is a precursor of the chemical reactions behind the accelerated formation of the 2223 phase.The photoresponse of PbBiSrCaCuO film was investigated at temperatures below, around, and beyond Tc. Consistency was found between photoresponse and temperature derivative of film resistivity near Tc, suggesting that the photoresponse is bolometric in origin. Other bolometric signatures include the long recovery time and linear dependence of photoresponse with supplied current. Below Tc, a fast response appeared when the power density of optical excitation exceeded a certain threshold. The effect of bias temperature on transient structure, magnitude, and time delay of the fast response showed that this response is also bolometric. A bolometric model was developed using the solutions of the problem of linear heat flow in a solid bounded by a pair of parallel planes. The photoresponses predicted by this model were in good agreement with those obtained experimentally. Beyond T c, it was found that a nonbolometric photoresponse coexists with the bolometric counterpart in electrically biased films. These components superimpose linearly and can be extracted from the responses measured with forward and reverse bias currents. The nonbolometric component also manifested itself as the response of electrically unbiased films. Its behavior was consistent with prediction of a model based on the Seebeck effect. In this model the film was depicted as a number of parallel layers having different thermopowers and forming a tilt angle to the substrate surface. Such a structure can be seen as the equivalent of a number of thermocouples connected in series along the length of the film. Upon thermal heating of the film, the temperature gradient in the individual thermocouples results in Seebeck voltages that add up to the transverse nonbolometric voltage

Sheath-wave related resonances in the frequency response of a cylindrical monopole in a plasma

Experimental details -- Results -- Discussion

Efficacy and safety of zero‐fluoroscopy ablation of ventricular arrhythmias originating from the right ventricular outflow tract: Comparison with fluoroscopy‐guided ablation without a three‐dimensional electroanatomic mapping system

Abstract Background Radiofrequency catheter ablation is the preferred treatment choice for ventricular arrhythmias (VAs) originating from right ventricular outflow tract (RVOT) in symptomatic patients and is usually performed under fluoroscopy guidance. Zero‐fluoroscopy (ZF) ablations using 3D mapping system applied for treatment of various types of arrhythmias are trending and practiced in many centers around the world, but rarely done in Vietnam. The objective of this study was to evaluate the efficacy and safety of zero‐fluoroscopy ablation of RVOT VAs, compared with fluoroscopy‐guided ablation without a 3D electroanatomic mapping (EAM) system. Methods and Results We conducted a nonrandomized, prospective single‐center study including 114 patients with RVOT VAs that had electrocardiographic features of typical left bundle branch block, inferior axis QRS morphology, and a precordial transition ≥ V3, from May 2020 to July 2022. The patients were assigned (without randomization) to two different approaches of either zero‐fluoroscopy ablation under the guidance of the Ensite system (ZF group) or fluoroscopy‐guided ablation without a 3D EAM (fluoroscopy group) in a 1:1 ratio. After a follow‐up time of 5.0 ± 4.9 months and 6.9 ± 9.3 months in the ZF and fluoroscopy groups, respectively, the results showed a higher success rate in the fluoroscopy group than in the complete ZF group (87.3% vs 86.8%), although the difference was not statistically significant. No major complication was noted in both the groups. Conclusion ZF ablation for RVOT VAs can be done safely and effectively using the 3D electroanatomic mapping system. The results of ZF approach are comparable to that of the fluoroscopy‐guided approach without a 3D EAM system

Utilization of Response Surface Methodology in Optimization of Polysaccharides Extraction from Vietnamese Red Ganoderma lucidum by Ultrasound-Assisted Enzymatic Method and Examination of Bioactivities of the Extract

Red Ganoderma lucidum (G. lucidum) is a popular medicinal herb commonly used in Vietnamese traditional remedies due to its potential value for health. In this study, polysaccharides were extracted from G. lucidum using ultrasound-assisted enzymatic extraction method. The response surface methodology and Box–Behnken design were employed to investigate the effects of pH, extraction temperature, extraction time, and ultrasonic power on the content of polysaccharides. Based on ultraviolet-visible spectroscopy analysis, the highest content of polysaccharides in the extract was 32.08 mg/g under optimum experimental parameters including enzyme concentration of 3%, pH of 5.5, extraction temperature of 45°C, extraction time of 30 min, and ultrasonic power of 480 W. The Fourier-transform infrared spectroscopy was also used to identify the functional groups in the extracts. The molecular weights of polysaccharides were determined by gel permeation chromatography. The obtained extract was then evaluated for anticancer activities by using (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, showing the anticancer activities with the half-maximal inhibitory concentration value of more than 512 μg/mL. This result suggested that UAEE could be considered as an appropriate and effective extraction method for bioactive crude polysaccharides from G. lucidum