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991.
Konstantis F. Konidaris Michalis Kaplanis Catherine P. Raptopoulou Spyros P. Perlepes Evy Manessi-Zoupa Eugenia Katsoulakou 《Polyhedron》2009
The initial employment of pyridine-3-carbaldehyde oxime, (3-py)C(H)NOH, and pyridine-4-carbaldehyde oxime, (4-py)C(H)NOH, in zinc(II) carboxylate chemistry is reported. The syntheses, crystal structures and IR characterization are described for [Zn3(O2CPh)6{(3-py)C(H)NOH}2] (1) and [Zn2(O2CPh)4{(4-py)C(H)NOH}2] (2). The trinuclear molecule of 1 has a linear structure, with one monoatomically bridging η1:η2:μ and two syn, syn-η1:η1:μ benzoate groups spanning each pair of ZnII ions; the terminal metal ions are each capped by one (3-py)C(H)NOH ligand coordinating through its pyridyl nitrogen. Complex 2 exhibits a dinuclear paddle–wheel structure with a Zn···Zn distance of 2.990(2) Å; each ZnII ion has a square pyramidal geometry with four carboxylate oxygens in the basal plane and the pyridyl nitrogen of one monodentate (4-py)C(H)NOH ligand at the apex. Both complexes form 1D architectures by virtue of hydrogen bonding interactions involving the free oxime group as donor and the oxime nitrogen (1) or carboxylate oxygens (2) as acceptors. IR data are discussed in terms of the known structures and coordination modes of the ligands. 相似文献
992.
Hireche O Weisman C Baltean-Carlès D Le Quéré P Bauwens L 《The Journal of the Acoustical Society of America》2010,128(6):3438-3448
A model of an idealized thermoacoustic engine is formulated, coupling nonlinear flow and heat exchange in the heat exchangers and stack with a simple linear acoustic model of the resonator and load. Correct coupling results in an asymptotically consistent global model, in the small Mach number approximation. A well-resolved numerical solution is obtained for two-dimensional heat exchangers and stack. The model assumes that the heat exchangers and stack are shorter than the overall length by a factor of the order of a representative Mach number. The model is well-suited for simulation of the entire startup process, whereby as a result of some excitation, an initially specified temperature profile in the stack evolves toward a near-steady profile, eventually reaching stationary operation. A validation analysis is presented, together with results showing the early amplitude growth and approach of a stationary regime. Two types of initial excitation are used: Random noise and a small periodic wave. The set of assumptions made leads to a heat-exchanger section that acts as a source of volume but is transparent to pressure and to a local heat-exchanger model characterized by a dynamically incompressible flow to which a locally spatially uniform acoustic pressure fluctuation is superimposed. 相似文献
993.
Matthieu Virot Valérie Tomao Carine Le Bourvellec Catherine M.C.G. Renard Farid Chemat 《Ultrasonics sonochemistry》2010,17(6):1066-1074
Apple pomace, a by-product of the cider production, has been studied as a potential source of polyphenols, compounds of great interest for the industry. Ultrasound has been used to improve extraction efficiency in terms of time needed and total polyphenol content. A preliminary study has been first investigated to optimize ethanol proportion of aqueous extractant (50%, v/v) and solid/liquid ratio (<15%, w/v). A response surface methodology has then been used to maximize total polyphenol content of extracts and investigate influence of parameters involved in extraction procedures for both total polyphenols content and composition of extracts. Optimal settings reached from a central composite design were applied for ultrasound-assisted extraction and were compared to conventional procedure: yields were increased by more than 20%. Ultrasound-assisted polyphenols extraction from apple pomace appears to be a relevant, rapid, sustainable alternative to conventional procedure, and that scale up of the process is possible. 相似文献
994.
Serdar Durdagi Manthos G. Papadopoulos Panagiotis G. Zoumpoulakis Catherine Koukoulitsa Thomas Mavromoustakos 《Molecular diversity》2010,14(2):257-276
When X-ray structure of a ligand-bound receptor is not available, homology models of the protein of interest can be used to
obtain the ligand-binding cavities. The steroelectronic properties of these cavities are directly related to the performed
molecular model coordinates. Thus, the use of different template structures for homology may result in variation of ligand-binding
modes. We have recently reported the MD simulations of a potent CB ligand at bovine rhodopsin-based CB1 and CB2 receptors
(Durdagi et al., Bioorg Med Chem 16:7377–7387, 2008). In this present study, a homology modeling study based on the β2-adrenergic receptor for both CB1 and CB2 receptors was performed, and the results were compared with rhodopsin-based models.
In addition, the role of membrane bilayers to the adopted conformations of potent AMG3 CB ligand has been analyzed for receptor-free
and membrane-associated receptor systems. The performed MD trajectory analysis results have shown that gauche conformations at the terminal segment of the alkyl side chain of AMG3 are not favored in solution. Different adopting dihedral
angles defined between aromatic and dithiolane rings at the active sites of the CB1 and CB2 receptors, which are adapted lead
to different alkyl side chain orientations and thus, may give clues to the medicinal chemists to synthesize more selective
CB ligands. The binding sites of receptors derived by rhodopsin-based models have been regenerated using the β2-adrenergic based template receptors. The re-obtained models confirmed the ligand-binding pockets that were derived based
on rhodopsin. 相似文献
995.
We organized and led a European study course for American undergraduate university students to explore the early history of relativity and quantum theory. We were inspired by The Physical Tourist articles published in this journal on Munich, Bern, Berlin, Copenhagen, and Göttingen. We describe this adventure both for others wishing to teach such a course and for anyone wishing to walk in the footsteps of the physicists who revolutionized physics in the early decades of the twentieth century. 相似文献
996.
Newly generated cells are increased in hippocampus of adult mice lacking a serine protease inhibitor
Maddalena M Lino Catherine Vaillant Slobodanka Orolicki Melanie Sticker Mirna Kvajo Denis Monard 《BMC neuroscience》2010,11(1):70
Background
Neurogenesis in the hippocampal dentate gyrus and the subventricular zone occurs throughout the life of mammals and newly generated neurons can integrate functionally into established neuronal circuits. Neurogenesis levels in the dentate gyrus are modulated by changes in the environment (enrichment, exercise), hippocampal-dependent tasks, NMDA receptor (NMDAR) activity, sonic hedgehog (SHH) and/or other factors. 相似文献997.
Teo Lombardo Lidia Lancellotti Christelle Souprayen Catherine Sella Laurent Thouin 《Electroanalysis》2019,31(11):2103-2111
Microfluidic devices were designed to electrochemically detect in a two‐phase flow the velocity, size and content of aqueous droplets containing redox species. The principle of these determinations is based on the analysis of a unique chronoamperometric response recorded during the passage of a droplet over channel microelectrodes. Two configurations of electrochemical cell with different geometries were investigated both theoretically and experimentally. Velocity and size of droplets, as well as internal recirculating convection within droplets, were evaluated from chronoamperometric curves by specific transition times depending on the cell configuration. In addition, the droplet content was probed from the Faradaic current controlled by mass transport and by internal hydrodynamic regime. For droplet velocity and size, experimental data were systematically compared to optical measurements. All the results demonstrated the high performance of the electrochemical detection reached under these conditions. They successfully validate the concept of self‐consistent electrochemical detections of aqueous droplets within microchannels for the simultaneous determination of their velocity, size and content. 相似文献
998.
Catherine Silvestre 《The European Physical Journal C - Particles and Fields》2009,61(4):841-845
In this paper, we calculate the decay rates of the D
+→D
0
e
+
ν, D
S
+→D
0
e
+
ν,
, D
S
+→D
+
e
−
e
+ and B
S
0→B
0
e
−
e
+ semileptonic decay processes, in which only the light quarks decay, while the heavy flavors remain unchanged. The branching
ratios of these decay processes are calculated with the flavor SU(3) symmetry. The uncertainties are estimated by considering
the SU(3) breaking effect. We find that the decay rates are very tiny in the framework of the standard model. We also estimate
the sensitivities of the measurements of these rare decays at future experiments, such as BES-III, super-B and LHC-b. 相似文献
999.
Jianli Wang Long Pu Yujia Han Shuyin Wu Gang Tang Sandong Guo Catherine Stampfl 《The European Physical Journal B - Condensed Matter and Complex Systems》2017,90(9):178
The replacement of traditional SiO2 with high-k oxides allows the physical thickness of the gate dielectric to be thinner without the tunneling problem in Si-based metal-oxide-semiconductor field-effect transistors. LaAlO3 appears to be a promising high-k material for use in future ultra large scale integrated devices. In the present paper, the electronic properties of Si/LaAlO3 (001) heterojunctions are investigated by first-principles calculations. We studied the initial adsorption of Si atoms on the LaAlO3 (001) surface, and found that Si atoms preferentially adsorb on top of oxygen atoms at higher coverage. The surface phase diagrams indicate that Si atoms may substitute oxygen atoms at the LaO-terminated surface. The band offsets, electronic density of states, and atomic charges are analyzed for the various Si/LaAlO3 heterojunctions. Our results suggest that the Si/AlO2 interface is suitable for the design of metal oxide semiconductor devices because the valence and conduction band offsets are both larger than 1 eV. 相似文献
1000.
Marro KI Lee D Shankland EG Mathis CM Hayes CE Amara CE Kushmerick MJ 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2008,195(1):67-75
The limited bandwidths of volume selective RF pulses in localized in vivo MRS experiments introduce spatial artifacts that complicate spectral quantification of J-coupled metabolites. These effects are commonly referred to as a spatial interference or "four compartment" artifacts and are more pronounced at higher field strengths. The main focus of this study is to develop a generalized approach to numerical simulations that combines full density matrix calculations with 3D localization to investigate the spatial artifacts and to provide accurate prior knowledge for spectral fitting. Full density matrix calculations with 3D localization using experimental pulses were carried out for PRESS (TE=20, 70 ms), STEAM (TE=20, 70 ms) and LASER (TE=70 ms) pulse sequences and compared to non-localized simulations and to phantom solution data at 4 T. Additional simulations at 1.5 and 7 T were carried out for STEAM and PRESS (TE=20 ms). Four brain metabolites that represented a range from weak to strong J-coupling networks were included in the simulations (lactate, N-acetylaspartate, glutamate and myo-inositol). For longer TE, full 3D localization was necessary to achieve agreement between the simulations and phantom solution spectra for the majority of cases in all pulse sequence simulations. For short echo time (TE=20 ms), ideal pulses without localizing gradients gave results that were in agreement with phantom results at 4 T for STEAM, but not for PRESS (TE=20). Numerical simulations that incorporate volume localization using experimental RF pulses are shown to be a powerful tool for generation of accurate metabolic basis sets for spectral fitting and for optimization of experimental parameters. 相似文献