http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Physical Modeling of SiC Power Diodes with Empirical Approximation
Hernandez, Leobardo,Claudio, Abraham,Rodriguez, Marco A.,Ponce, Mario,Tapia, Alejandro The Korean Institute of Power Electronics 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.3
This article presents the development of a model for SiC power diodes based on the physics of the semiconductor. The model is able to simulate the behavior of the dynamics of the charges in the N- region based on the stored charge inside the SiC power diode, depending on the working regime of the device (turn-on, on-state, and turn-off). The optimal individual calculation of the ambipolar diffusion length for every phase of commutation allows for solving the ambipolar diffusion equation (ADE) using a very simple approach. By means of this methodology development a set of differential equations that models the main physical phenomena associated with the semiconductor power device are obtained. The model is developed in Pspice with acceptable simulation times and without convergence problems during its implementation.
Lihua Wei,Miguel A. PEREZ-RODRIGUEZ,Mario A. RODRIGUEZ-PEREZ 한국곤충학회 2016 Entomological Research Vol.46 No.3
Baculoviruses can be genetically engineered to express foreign genes; thus, their lethal potency and host range can be improved to produce more virulent bioinsecticides. Polydnavirus (PDV) genes have insecticidal bioactivities and could enhance the pathogenicity of the baculoviruses to control insect pests. The CrV1 gene from Cotesia rubecula polydnavirus is responsible for depolymerization of actin cytoskeleton in hemocytes, disabling its spread on foreign object surfaces. In this study, we tested the efficacy of the recombinant baculovirus (AcMNPV‐CrV1) under p10 promoter against second instar P. rapae larvae. The expression of the CrV1 gene in P. rapae larvae was verified with reverse transcription–polymerase chain reaction (RT‐PCR). AcMNPV‐CrV1 showed a significantly lower median lethal concentration (LC50) and shorter median lethal time (LT50) as compared with the AcMNPV wild‐type virus. These results suggested that the expression of CrV1 protein could successfully improve the insecticidal toxicity of baculovirus.
Physical Modeling of SiC Power Diodes with Empirical Approximation
Leobardo Hern´andez,Abraham Claudio,Marco A. Rodriguez,Mario Ponce,Alejandro Tapia 전력전자학회 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.3
This article presents the development of a model for SiC power diodes based on the physics of the semiconductor. The model is able to simulate the behavior of the dynamics of the charges in the N- region based on the stored charge inside the SiC power diode, depending on the working regime of the device (turn-on, on-state, and turn-off). The optimal individual calculation of the ambipolar diffusion length for every phase of commutation allows for solving the ambipolar diffusion equation (ADE) using a very simple approach. By means of this methodology development a set of differential equations that models the main physical phenomena associated with the semiconductor power device are obtained. The model is developed in Pspice with acceptable simulation times and without convergence problems during its implementation.
Isolation and Molecular Characterization of Xylella fastidiosa from Coffee Plants in Costa Rica
Mauricio Montero-Astua,Carlos Chacon-Diaz,Estela Aguilar,Carlos Mario Rodriguez,Laura Garita,William Villalobos,Lisela Moreira,John S. Hartung,Carmen Rivera 한국미생물학회 2008 The journal of microbiology Vol.46 No.5
Coffee plants exhibiting a range of symptoms including mild to severe curling of leaf margins, chlorosis and deformation of leaves, stunting of plants, shortening of internodes, and dieback of branches have been reported since 1995 in several regions of Costa Rica’s Central Valley. The symptoms are referred to by coffee producers in Costa Rica as “crespera” disease and have been associated with the presence of the bacterium Xylella fastidiosa. Coffee plants determined to be infected by the bacterium by enzyme linked immunosorbent assay (ELISA), were used for both transmission electron microscopy (TEM) and for isolation of the bacterium in PW broth or agar. Petioles examined by TEM contained rod-shaped bacteria inside the xylem vessels. The bacteria measured 0.3 to 0.5 μm in width and 1.5 to 3.0 μm in length, and had rippled cell walls 10 to 40 nm in thickness, typical of X. fastidiosa. Small, circular, dome-shaped colonies were observed 7 to 26 days after plating of plant extracts on PW agar. The colonies were comprised of Gram-negative rods of variable length and a characteristic slight longitudinal bending. TEM of the isolated bacteria showed characteristic rippled cell walls, similar to those observed in plant tissue. ELISA and PCR with specific primer pairs 272-1-int/272-2-int and RST31/RST33 confirmed the identity of the isolated bacteria as X. fastidiosa. RFLP analysis of the amplification products revealed diversity within X. fastidiosa strains from Costa Rica and suggest closer genetic proximity to strains from the United States of America than to other coffee or citrus strains from Brazil.
The Learning Curve for Peroral Endoscopic Myotomy in Latin America: A Slide to the Right?
Michel Kahaleh,Amy Tyberg,Supriya Suresh,Arnon Lambroza,Fernando Rodriguez Casas,Mario Rey,Jose Nieto,Guadalupe Ma Martínez,Felipe Zamarripa,Vitor Arantes,Maria G Porfilio,Monica Gaidhane,Pietro Fami 대한소화기내시경학회 2021 Clinical Endoscopy Vol.54 No.5
Background/Aims: Peroral endoscopic myotomy (POEM) has been increasingly used for achalasia in Latin America, where Chagasdisease is prevalent, and this makes POEM more challenging. The aim of this study was to determine the learning curve for POEMin Latin America. Methods: Patients undergoing POEM in Latin America with a single operator were included from a prospective registry over 4 years. Non-linear regression and cumulative sum control chart (CUSUM) analyses were conducted for the learning curve. Results: A total of 125 patients were included (52% male; mean age, 59 years), of which 80 had type II achalasia (64%), and 38 hadChagas disease (30%). The average pre-procedure and post-procedure Eckardt scores were 6.79 and 1.87, respectively. Technicalsuccess was achieved in 93.5% of patients, and clinical success was achieved in 88.8%. Adverse events occurred in 27 patients (22%)and included bleeding (4 patients), pneumothorax (4 patients), mucosal perforation (13 patients), mediastinitis (2 patients), andleakage (4 patients). The CUSUM chart showed a median procedure time of 97 min (range, 45-196 min), which was achieved at the 61st procedure. Procedure duration progressively decreased, with the last 10 procedures under 50 min approaching a plateau (p-value <0.01). Conclusions: Mastering POEM in Latin America requires approximately 61 procedures for both POEM efficiency and to accomplishthe procedure within 97 minutes.
Spindle-shaped viruses infect marine ammonia-oxidizing thaumarchaea
Kim, Jong-Geol,Kim, So-Jeong,Cvirkaite-Krupovic, Virginija,Yu, Woon-Jong,Gwak, Joo-Han,Ló,pez-Pé,rez, Mario,Rodriguez-Valera, Francisco,Krupovic, Mart,Cho, Jang-Cheon,Rhee, Sung-Keun National Academy of Sciences 2019 Proceedings of the National Academy of Sciences Vol.116 No.31
<P><B>Significance</B></P><P>Ammonia-oxidizing archaea (AOA) are major players in global nitrogen cycling. The physicochemical and metabolic factors affecting the composition of AOA communities and their efficiency of resource utilization have been studied extensively. However, viral predation on AOA remains unexplored due to lack of isolated virus–host systems. Here we report on the isolation and characterization of three <I>Nitrosopumilus</I> spindle-shaped viruses (NSVs) that infect AOA hosts. NSVs represent a potentially important group of marine viruses with a chronic infection cycle, providing important insights into the diversity and evolution of the archaeal virosphere. The wide spread of NSVs in AOA-containing marine environments suggests that NSV predation might regulate the diversity and dynamics of AOA communities, thereby affecting the carbon and nitrogen cycling.</P><P>Ammonia-oxidizing archaea (AOA) from the phylum Thaumarchaeota are ubiquitous in marine ecosystems and play a prominent role in carbon and nitrogen cycling. Previous studies have suggested that, like all microbes, thaumarchaea are infected by viruses and that viral predation has a profound impact on thaumarchaeal functioning and mortality, thereby regulating global biogeochemical cycles. However, not a single virus capable of infecting thaumarchaea has been reported thus far. Here we describe the isolation and characterization of three <I>Nitrosopumilus</I> spindle-shaped viruses (NSVs) that infect AOA and are distinct from other known marine viruses. Although NSVs have a narrow host range, they efficiently infect autochthonous <I>Nitrosopumilus</I> strains and display high rates of adsorption to their host cells. The NSVs have linear double-stranded DNA genomes of ∼28 kb that do not display appreciable sequence similarity to genomes of other known archaeal or bacterial viruses and could be considered as representatives of a new virus family, the “Thaspiviridae.” Upon infection, NSV replication leads to inhibition of AOA growth, accompanied by severe reduction in the rate of ammonia oxidation and nitrite reduction. Nevertheless, unlike in the case of lytic bacteriophages, NSV propagation is not associated with detectable degradation of the host chromosome or a decrease in cell counts. The broad distribution of NSVs in AOA-dominated marine environments suggests that NSV predation might regulate the diversity and dynamics of AOA communities. Collectively, our results shed light on the diversity, evolution, and potential impact of the virosphere associated with ecologically important mesophilic archaea.</P>