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91.
Carmieli R Manikandan P Kalb Gilboa AJ Goldfarb D 《Journal of the American Chemical Society》2001,123(34):8378-8386
High-field (95 GHz) pulsed EPR and electron-nuclear double resonance (ENDOR) techniques have been used for the first time to determine coordinates of ligand protons of a high-spin metal center in a protein single crystal. The protein concanavalin A contains a Mn(2+) ion which is coordinated to two water molecules, a histidine residue, and three carboxylates. Single crystals of concanavalin A were grown in H(2)O and in D(2)O to distinguish the exchangeable water protons from the nonexchangeable protons of the imidazole group. Distinct EPR transitions were selected by performing the ENDOR measurements at different magnetic fields within the EPR spectrum. This selection, combined with the large thermal polarization achieved at 4.5 K and a magnetic field of approximately 3.4 T allowed us to assign the ENDOR signals to their respective M(S) manifolds, thus providing the signs of the hyperfine couplings. Rotation patterns were acquired in the ac and ab crystallographic planes. Two distinct crystallographic sites were identified in each plane, and the hyperfine tensors of two of the imidazole protons and the four water protons were determined by simulations of the rotation patterns. All protons have axially symmetric hyperfine tensors and, by applying the point-dipole approximation, the positions of the various protons relative to the Mn(2+) ion were determined. Likewise, the water protons involved in H-bonding to neighboring residues were identified using the published, ultrahigh-resolution X-ray crystallographic coordinates of the protein (Deacon et al. J. Chem. Soc., Faraday Trans. 1997, 93(24), 4305-4312). 相似文献
92.
93.
Propagation-invariant vectorial Bessel beams with linearly polarized axial symmetry based on quantized Pancharatnam-Berry phase optical elements are described. The geometric phase is formed through the use of discrete computer-generated space-variant subwavelength dielectric gratings. We have verified the polarization properties of our elements for laser radiation at 10.6-microm wavelength and also demonstrated propagation-invariant, controlled rotation of a propeller-shaped intensity pattern through the simple rotation of a polarizer. 相似文献
94.
LetG be a finite transitive permutation group on a finite setS. LetA be a nonempty subset ofS and denote the pointwise stabilizer ofA inG byC
G
(A). Our main result is the following inequality: [G :C
G
(A)]≥|G||A|/|S|.
This paper is a part of the author’s Ph.D. thesis research, carried out at Tel Aviv University under the supervision of Professor
Marcel Herzog. 相似文献
95.
Avi Lin 《国际流体数值方法杂志》1985,5(4):381-391
A new method for solving elliptic difference equations is derived based on the strongly implicit method. This parametrized strongly implicit method has three free parameters which may be functions of the field's nodal point. The method has some resemblance to the SOR techniques, but in the present method the off-diagonal entries are also over-relaxed. The main application of this method is for transport equations such as those governing the fluid flow and heat transfer fields. 相似文献
96.
Lavi A Cohen H Bendikov T Vilan A Cahen D 《Physical chemistry chemical physics : PCCP》2011,13(4):1293-1296
We show that electronic transport quality alkyl chain mono-layers can be prepared from dilute solution, rather than from neat alkanes, and on Si (100) instead of (111) surfaces. High monolayer quality was deduced from XPS and from comparing current-voltage curves of Hg/alkyl/Si junctions with those for junctions with monolayers made from neat alkanes. XPS shows that limited surface oxidation does not harm the integrity of the monolayer. Solution preparation significantly widens the range of molecules that can be used for transport studies. 相似文献
97.
It has been shown that the orbits of motion for a wide class of non-relativistic Hamiltonian systems can be described as geodesic
flows on a manifold and an associated dual by means of a conformal map. This method can be applied to a four dimensional manifold
of orbits in spacetime associated with a relativistic system. We show that a relativistic Hamiltonian which generates Einstein
geodesics, with the addition of a world scalar field, can be put into correspondence in this way with another Hamiltonian
with conformally modified metric. Such a construction could account for part of the requirements of Bekenstein for achieving
the MOND theory of Milgrom in the post-Newtonian limit. The constraints on the MOND theory imposed by the galactic rotation
curves, through this correspondence, would then imply constraints on the structure of the world scalar field. We then use
the fact that a Hamiltonian with vector gauge fields results, through such a conformal map, in a Kaluza-Klein type theory,
and indicate how the TeVeS structure of Bekenstein and Saunders can be put into this framework. We exhibit a class of infinitesimal gauge transformations
on the gauge fields Um(x){\mathcal{U}}_{\mu}(x) which preserve the Bekenstein-Sanders condition UmUm=-1{\mathcal{U}}_{\mu}{\mathcal{U}}^{\mu}=-1. The underlying quantum structure giving rise to these gauge fields is a Hilbert bundle, and the gauge transformations induce
a non-commutative behavior to the fields, i.e. they become of Yang-Mills type. Working in the infinitesimal gauge neighborhood
of the initial Abelian theory we show that in the Abelian limit the Yang-Mills field equations provide residual nonlinear
terms which may avoid the caustic singularity found by Contaldi et al. 相似文献
98.
Aamodt K Abelev B Abrahantes Quintana A Adamová D Adare AM Aggarwal MM Aglieri Rinella G Agocs AG Agostinelli A Aguilar Salazar S Ahammed Z Ahmad N Ahmad Masoodi A Ahn SU Akindinov A Aleksandrov D Alessandro B Alfaro Molina R Alici A Alkin A Almaráz Aviña E Alt T Altini V Altsybeev I Andrei C Andronic A Anguelov V Anson C Antičić T Antinori F Antonioli P Aphecetche L Appelshäuser H Arbor N Arcelli S Arend A Armesto N Arnaldi R Aronsson T Arsene IC Arslandok M Asryan A Augustinus A Averbeck R 《Physical review letters》2011,107(3):032301
We report on the first measurement of the triangular v3, quadrangular v4, and pentagonal v5 charged particle flow in Pb-Pb collisions at sqrt(s(NN)) = 2.76 TeV measured with the ALICE detector at the CERN Large Hadron Collider. We show that the triangular flow can be described in terms of the initial spatial anisotropy and its fluctuations, which provides strong constraints on its origin. In the most central events, where the elliptic flow v2 and v3 have similar magnitude, a double peaked structure in the two-particle azimuthal correlations is observed, which is often interpreted as a Mach cone response to fast partons. We show that this structure can be naturally explained from the measured anisotropic flow Fourier coefficients. 相似文献
99.
Aamodt K;ALICE Collaboration Abrahantes Quintana A Adamová D Adare AM Aggarwal MM Aglieri Rinella G Agocs AG Aguilar Salazar S Ahammed Z Ahmad N Ahmad Masoodi A Ahn SU Akindinov A Aleksandrov D Alessandro B Alfaro Molina R Alici A Alkin A Almaráz Aviña E Alt T Altini V Altinpinar S Altsybeev I Andrei C Andronic A Anguelov V Anson C Antičić T Antinori F Antonioli P Aphecetche L Appelshäuser H Arbor N Arcelli S Arend A Armesto N Arnaldi R Aronsson T Arsene IC Asryan A Augustinus A Averbeck R 《Physical review letters》2011,106(3):032301
The centrality dependence of the charged-particle multiplicity density at midrapidity in Pb-Pb collisions at sqrt[s_{NN}]=2.76 TeV is presented. The charged-particle density normalized per participating nucleon pair increases by about a factor of 2 from peripheral (70%-80%) to central (0%-5%) collisions. The centrality dependence is found to be similar to that observed at lower collision energies. The data are compared with models based on different mechanisms for particle production in nuclear collisions. 相似文献
100.
Avi Singh 《Phase Transitions》2013,86(11):990-1008
The study aimed to explore the influence of eleven excipients (in three groups) on the phase transition of CaCO3. The groups were; Group 1: Ca-TEG (CaCO3- Tetraethylene Glycol), Ca-PVP (Polyvinylpyrollidone), Ca-LUT (Lutrol Micro 127 MP), Ca-HPMC (Hydroxypropylmethyl Cellulose) and Ca-Blank, Group 2: Ca-G44/14 (Gelucire 44/14), Ca-CRH40 (Cremophor RH40), Ca-SHS (Solutol HS15), Ca-LAB (Labrasol) and Group 3: Ca-GE (Garlic extract), Ca-CAS (Casein), Ca-TCT (Transcutol). Group 1 confers the characteristics of only Calcite, while, Group 2, gave the highest mole fraction of Vaterite. Group 3 gave the highest mole fraction of Vaterite followed by Calcite/Aragonite. FESEM of Ca-CRH40 illustrated numerous parallel stacks of nano-hexagonal vaterite columns building the inner structure of bacillus type Vaterite, while that of Ca-TCT suggested the presence of sunflower shaped Vaterite particles and rhombohedral calcite. The % dissolution efficiency was found maximum for Ca-TEG (90.65%) followed by Ca-PVP (86.13%), Ca-HPMC (76.25%), Ca-LUT (52.12%) and CaBlank (22.96%). 相似文献