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Experimental and Numerical Investigation of the Erosive Potential of a Leading Edge Cavity
Jean-Bastien Carrat,Regiane Fortes-Patella,Jean-Pierre Franc 한국유체기계학회 2019 International journal of fluid machinery and syste Vol.12 No.2
This paper presents a joint experimental and numerical analysis of the erosive potential of an unsteady cavity that develops at the leading edge of a two-dimensional hydrofoil and periodically sheds vapour clouds. From an experimental viewpoint, the erosive potential was characterized by pressure pulse height spectra. The hydrofoil was equipped with eight pressure sensors made of PVDF piezoelectric film that allowed the measurement of flow aggressiveness at different locations along the hydrofoil chord. It was shown that the mean peak rate over a large number of cavity pulsations exhibits a maximum at a distance from the leading edge close to the maximum cavity length. Moreover, the increase in flow aggressiveness caused by an increase in flow velocity can be explained by an increase in both amplitude and frequency of impact loads. From a numerical viewpoint, the unsteady Reynolds averaged Navier-Stokes (RANS) equations were solved using a modified k-ε RNG turbulence model together with a homogeneous cavitation model within a two-dimensional approach. Flow aggressiveness was estimated from the Lagrangian derivative of the computed void fraction that allows identifying the regions of collapse of vapour structures. Three different critical regions from an erosive viewpoint were numerically identified. Apart from the region of collapse of the shed cloud (which was not instrumented in the present study), the computations showed a maximum of aggressiveness around the maximum cavity length as found experimentally. Another region of high aggressiveness closer to the leading edge and associated to the upward movement of the re-entrant jet was predicted by the present numerical model but not confirmed experimentally, which probably shows the limitation of a two-dimensional approach.
Microstrip EHF Butler Matrix Design and Realization
Jean-Sébastien Néron,Gilles-Y. Delisle 한국전자통신연구원 2005 ETRI Journal Vol.27 No.6
This paper describes the design and realization of an extra high frequency band 8 × 8 microstrip Butler matrix. Operation at 36 GHz is achieved with a frequency bandwidth exceeding 400 MHz. The circuit is implemented on a bi-layer microstrip structure using conventional manufacturing processes. This planar implementation of a Butler matrix is a key component of a switched beam smart antenna with printed antenna elements integrated on-board. Conception details, simulation results, and measurements are also given for the components (hybrid couplers, cross-couplers, and vertical inter-connections) used to implement the matrix.
Dubé,e, Vincent,Triboulet, Sé,bastien,Mainardi, Jean-Luc,Ethè,ve-Quelquejeu, Mé,lanie,Gutmann, Laurent,Marie, Arul,Dubost, Lionel,Hugonnet, Jean-Emmanuel,Arthur, Michel American Society for Microbiology 2012 Antimicrobial agents and chemotherapy Vol.56 No.8
<B>ABSTRACT</B><P>The structure ofMycobacterium tuberculosispeptidoglycan is atypical since it contains a majority of 3→3 cross-links synthesized byl,d-transpeptidases that replace 4→3 cross-links formed by thed,d-transpeptidase activity of classical penicillin-binding proteins. Carbapenems inactivate thesel,d-transpeptidases, and meropenem combined with clavulanic acid is bactericidal against extensively drug-resistantM. tuberculosis. Here, we used mass spectrometry and stopped-flow fluorimetry to investigate the kinetics and mechanisms of inactivation of the prototypicM. tuberculosisl,d-transpeptidase LdtMt1by carbapenems (meropenem, doripenem, imipenem, and ertapenem) and cephalosporins (cefotaxime, cephalothin, and ceftriaxone). Inactivation proceeded through noncovalent drug binding and acylation of the catalytic Cys of LdtMt1, which was eventually followed by hydrolysis of the resulting acylenzyme. Meropenem rapidly inhibited LdtMt1, with a binding rate constant of 0.08 μM<SUP>−1</SUP>min<SUP>−1</SUP>. The enzyme was unable to recover from this initial binding step since the dissociation rate constant of the noncovalent complex was low (<0.1 min<SUP>−1</SUP>) in comparison to the acylation rate constant (3.1 min<SUP>−1</SUP>). The covalent adduct resulting from enzyme acylation was stable, with a hydrolysis rate constant of 1.0 × 10<SUP>−3</SUP>min<SUP>−1</SUP>. Variations in the carbapenem side chains affected both the binding and acylation steps, ertapenem being the most efficient LdtMt1inactivator. Cephalosporins also formed covalent adducts with LdtMt1, although the acylation reaction was 7- to 1,000-fold slower and led to elimination of one of the drug side chains. Comparison of kinetic constants for drug binding, acylation, and acylenzyme hydrolysis indicates that carbapenems and cephems can both be tailored to optimize peptidoglycan synthesis inhibition inM. tuberculosis.</P>
Borondifluoride complexes of hemicurcuminoids as bio-inspired push–pull dyes for bioimaging
Kim, Eunsun,Felouat, Abdellah,Zaborova, Elena,Ribierre, Jean-Charles,Wu, Jeong Weon,Senatore, Sé,bastien,Matthews, Cé,dric,Lenne, Pierre-Franç,ois,Baffert, Carole,Karapetyan, Artak,G The Royal Society of Chemistry 2016 Organic & Biomolecular Chemistry Vol.14 No.4
<P>Hemicurcuminoids are based on half of the pi-conjugated backbone of curcuminoids. The synthesis of a series of such systems and their borondifluoride complexes is described. The electrochemical and photophysical properties of difluorodioxaborine species were investigated as a function of the nature of electron donor and acceptor groups appended at either terminal positions of the molecular backbone. The emissive character of these dipolar dyes was attributed to an intraligand charge transfer process, leading to fluorescence emission that is strongly dependent on solvent polarity. Quasi-quantitative quenching of fluorescence in high polarity solvents was attributed to photoinduced electron transfer. These dyes were shown to behave as versatile fluorophores. Indeed, they display efficient two-photon excited fluorescence emission leading to high two-photon brightness values. Furthermore, they form nanoparticles in water whose fluorescence emission quantum yield is less than that of the dye in solution, owing to aggregation-induced fluorescence quenching. When cos7 living cells were exposed to these weakly-emitting nanoparticles, one-and two-photon excited fluorescence spectra showed a strong emission within the cytoplasm that originated from the individual molecules. Dye uptake thus involved a disaggregation mechanism at the cell membrane which restored fluorescence emission. This off-on fluorescence switching allows a selective optical monitoring of those molecules that do enter the cell, which offers improved sensitivity and selectivity of detection for bioimaging purposes.</P>
Cytologic Aspect of Fibrous Osteodystrophy in a Juvenile Siberian Husky
지향,최을수,방동하,김대용,황철용,윤화영,Jean-Sébastien Latouche 한국임상수의학회 2009 한국임상수의학회지 Vol.26 No.1
A 5-month-old intact female Siberian Husky dog was presented for evaluation of severely enlarged maxilla. Abnormalities in CBC, serum chemistry and urinalysis indicated purulent inflammation and renal failure. Cytologic examination of the swollen maxilla showed a mixed population of multinucleated giant cells and round to polygonal to spindle shaped cells either individualized or aggregated. Both type of cells showed moderate anisokaryosis, and anisocytosis, prominent nucleolus or multiple nucleoli, and coarse chromatin. On histopathology maxilla and turbinate were diffusely expanded and replaced by variably dense fibrous connective tissue, and the kidneys showed changes consistent with renal dysplasia. Based on these findings, the diagnosis of fibrous osteodystrophy due to renal dysplasia and fibrosis was made. Despite the supportive care, the dog continued to decline and was euthanized.
Frigault Jonathan,Avoine Samuel,Drolet Sébastien,Letarte François,Bouchard Alexandre,Gagné Jean-Pierre,Thibault Claude,Grégoire Roger C.,Bouthillette Naomee Jutras,Gosselin Maude,Bouchard Philippe 대한대장항문학회 2023 Annals of Coloproctolgy Vol.39 No.2
Purpose: Laparoscopic right hemicolectomy (LRH) can be performed with an intracorporeal anastomosis (IA) or extracorporeal anastomosis (EA). It is not clear which technique is best. This study evaluated the impact of each anastomosis technique on perioperative safety and postoperative evolution. Methods: We performed a retrospective study at a tertiary colorectal surgery center. All patients who had an elective LRH from 2015 to 2019 were analyzed according to the anastomosis technique used. Results: In total, 285 patients were included in the study. IA was performed in 64 patients (22.5%). Mean operative time was longer in the patients with IA (IA, 160±31 minutes vs. EA, 138±42 minutes; P<0.001). No differences were observed in intraoperative complications, time to first bowel movement, length of stay, reoperation, or rehospitalization. Time to first flatus was longer in the patients with IA (P=0.049). At 30 days after surgery, there were no differences in the frequency of anastomotic leak (IA, 0% vs. EA, 2.3%; P=0.59), bleeding (IA, 3.1% vs. EA, 2.7%; P>0.99), or intraabdominal abscess (IA, 0% vs. EA, 0.5%; P>0.99). During follow-up, we noted more incisional hernias in patients with EA (IA, 1.6% vs. EA, 11.3%; P=0.01) and a trend toward more hernia in patients with EA in multivariate analysis (hazard ratio, 7.13; P=0.06). Anastomosis technique had no influence on recurrence. Conclusion: For LRH, both IA and EA are safe, with a low incidence of complications when performed by experienced surgeons. IA may be associated with a lower incidence of incisional hernia.
Lisa Humbertjean-Selton,Jérôme Selton,Nolwenn Riou-Comte,Jean-Christophe Lacour,Gioia Mione,Sébastien Richard 대한간학회 2018 Clinical and Molecular Hepatology(대한간학회지) Vol.24 No.4
Anemia appears frequently in patients with alcoholic liver disease (ALD) but has never been linked to bilateral nonarteritic anterior ischemic optic neuropathy (NAION). A 65-year-old woman with a medical history of alcoholic cirrhosis was admitted for bilateral NAION. On admission, she was found to have a low arterial pressure and severe normocytic anemia (48 g/L). The anemia was related to chronic bleeding due to antral gastritis along with other factors associated with ALD. The applied treatment consisted of urgent transfusion followed by high doses of proton-pump inhibitors, iron and vitamin supplementation, and support in lifestyle measures. Her hemoglobin levels remained stable after 2 years but the patient still suffered from visual loss. This case highlights the link between anemia and bilateral NAION in ALD patients. The optic nerve head is prone to infarction in this context due to the vascularization characteristics of ALD. Hemoglobin levels should be monitored in ALD patients to avoid the severe complication of NAION.