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81.
M. Lazar H. Vang P. Brosselard C. Raynaud P. Cremillieu J.-L. Leclercq A. Descamps S. Scharnholz D. Planson 《Superlattices and Microstructures》2006,40(4-6):388
SiC is currently an important topic in power devices. This new technology leads to lower power losses, faster switching, and higher working temperature. The design of SiC power devices requires the integration of edge termination techniques to obtain a high blocking voltage. The mesa structure approach is one well-established method. It could be used alone or in combination with a Junction Termination Extension (JTE). The mesa consists of a structure that removes material around the pn-junction. Due to the strong Si–C bonds, conventional chemical–wet etching solutions are inefficient on SiC, so plasma methods are required to etch SiC.The presented work is based on the use of an RIE reactor with an SF6/ O2 plasma. Its geometry structure and parameters were optimized. An etch rate of 0.35 μm/min was obtained without any trenching phenomenon. Trenches deeper than 10 μm deep were realized with a nickel etching mask that shows a high selectivity. AFM analysis revealed an etched surface as smooth as the initial one. 相似文献
82.
M. Lazar 《Annalen der Physik》2004,13(10):617-622
We show the correspondence between a screw dislocation in gradient elasticity and a regularized vortex. The effective Burgers vector, nonsingular distortion and stress fields of a screw dislocation and the effective circulation, smoothed velocity and momentum of a vortex are given and discussed. 相似文献
83.
Junko Matsuda Marie T. Vanier Iuliana Popa Jacques Portoukalian Kunihiko Suzuki 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2006,82(6):189-196
Gangliosides in the brain of the knockout mouse deficient in the activity of β1,4 N-acetylgalactosaminyl transferase (β1,4 GalNAc-T)(GM2 synthase) consisted of nearly exclusively of GM3- and GD3-gangliosides as expected from the known substrate specificity of the enzyme and in confirmation of the initial reports from two laboratories that generated the mutant mouse experimentally. The total molar amount of gangliosides was approximately 30% higher in the mutant mouse brain than that in the wild-type brain. However, contrary to the initial reports, one-fourth of total GD3-ganglioside was O-acetylated. It reacted positively with an anti-O-acetylated GD3 monoclonal antibody and disappeared with a corresponding increase in GD3-ganglioside after mild alkaline treatment. The absence of O-acetylated GD3 in the initial reports can be explained by the saponification step included in their analytical procedures. Although quantitatively much less and identification tentative, we also detected GT3 and O-acetylated GT3. Anti-GD3 and anti-O-acetylated GD3 monoclonal antibodies gave positive reactions in the brain of mutant mouse as expected from the analytical results. Either antibody barely stained wild-type brain except for immunoreactivity of GD3 in the cerebellar Purkinje cells. The distributions of GD3 and O-acetylated GD3 in the brain of mutant mouse were similar but differential localization was noted in the cerebellar Purkinje cells and cerebral cortex. 相似文献
84.
85.
The performance of a network subject to either state dependent or state independent flow control is investigated. In the state dependent case, the flow control policy is a function of the total number of packets for which the controller has not yet received an acknowledgment. In this case it is shown that the optimal flow control is a sliding window mechanism. The effect of the delayed feedback on the network performance as well as the size of the window are studied. The state independent optimal rate is also derived. The performance of the state dependent and state independent flow control policies are compared. Conditions for employing one of the two types of flow control policies for superior end-to-end network performance are discussed. All the results obtained are demonstrated using simple examples. 相似文献
86.
Rodica
Olar Mihaela Badea Veronica Lazar Carmen Balotescu Elena Cristurean Dana Marinescu 《Journal of Thermal Analysis and Calorimetry》2007,88(2):323-327
N,N-Dimethylbiguanide derivatives (HDMBG)X, where X=CH3COO
(1), Cl (2)
and NO3 (3) respectively,
exhibit in vitro antimicrobial activity
on representative bacterial and fungal strains. The presence of N,N-dimethylbiguanidium
ion for all derivatives was evidenced by IR and 1H
NMR spectra. Thermal analysis gave information on their decomposition steps
and also on the accompanying thermodynamic effects. According to TG and DTG
curves processes as melting, oxidative degradation as well as oxidative condensation
of –C=N– units occur. The different nature of the anions results
different melting points. Paracyanide formation at various condensation degrees
was observed. 相似文献
87.
The synthesis of various 2H-1,5-benzodioxepin and 2,5-dihydro-1,6-benzodioxocin derivatives is described. The key step involves the construction of seven- and eight-membered rings via ring-closing metathesis reaction. 相似文献
88.
Prof. Dr. C. Drăgulescu E. Petrovici Iuliana Lupu 《Monatshefte für Chemie / Chemical Monthly》1974,105(6):1184-1189
Complex compounds of trivalent metal chlorides (AlCl3, CrCl3, FeCl3) are described, which had been obtained in a double complexation reaction in CCl4 as a solvent with nitro compounds and SbCl5:M
III(C6H5NO2)
m
(SbCl6)3 (m=3,6),M
2
III(C6H5NO2)4(SbCl6)4 and Al(-C10H7NO2)3(SbCl6)3. Synthesis, analytical results and i.r. spectra are discussed. 相似文献
89.
90.
Daniela Iuliana Sora Elena Cristea Florin Albu Victor David Andrei Medvedovici 《Biomedical chromatography : BMC》2010,24(6):663-674
Analytical aspects related to the assay of pentoxifylline (PTX), lisofylline (M1) and carboxypropyl dimethylxanthine (M5) metabolites are discussed through comparison of two alternative analytical methods based on liquid chromatography separation and atmospheric pressure electrospray ionization tandem mass spectrometry detection. One method is based on a ‘pure’ reversed‐phase liquid chromatography mechanism, while the second one uses the additional polar interactions with embedded amide spacers linking octadecyl moieties to the silicagel surface (C‐18 Aqua stationary phase). In both cases, elution is isocratic. Both methods are equally selective and allows separation of unknowns (four species associated to PTX, two species associated to M1) detected through specific mass transitions of the parent compounds and owning respective structural confirmation. Plasma concentration–time patterns of these compounds follow typical metabolic profiles. It has been advanced that in‐vivo formation of conjugates of PTX and M1 is possible, such compounds being cleaved back to the parent ones within the ion source. The first method was associated with a sample preparation procedure based on plasma protein precipitation by strong organic acid addition. The second method used protein precipitation by addition of a water miscible organic solvent. Both analytical methods were fully validated and used to assess bioequivalence between a prolonged release generic formulation and the reference product, under multidose and single dose approaches. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献