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排序方式: 共有174条查询结果,搜索用时 15 毫秒
81.
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
82.
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
83.
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
84.
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
85.
Yamir Bandala Judit Aviña Tania González Ignacio A. Rivero Eusebio Juaristi 《Journal of Physical Organic Chemistry》2008,21(5):349-358
Thirty‐four novel α/β‐tetrapeptides ( 1–34 ) have been prepared employing solid‐phase and in‐parallel synthetic protocols. α/β ‐Tetrapeptides 1 – 34 were prepared by a combination of three α‐amino acid residues (alanine (Ala), phenylalanine (Phe), and isoleucine (Ile)) with one β‐amino acid residue (β3‐homophenylglycine). The corresponding complexes of several selected α/β‐tetrapeptides with alkali, alkaline earth, and transition metals, [tP + M+], were evaluated using ion electrospray‐ionization mass spectrometry (ESI‐MS). According to the results from analysis of mixtures, we can conclude that the position of the β‐amino acid is determinant in the affinity toward different metal cations. Computational modeling (DFT, B3LYP 6‐311++G) provided useful information regarding the most likely coordination sites of the metal ions on the receptor α/β‐tetrapeptide 12 , HO2C‐α‐Phe‐α‐Phe‐α‐Ile‐β3‐hPhg‐NH2, as well as the conformational changes induced by the metal upon [tP + M+] complex formation. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
86.
Avi Shalav Dinesh K. Venkatachalam Robert G. Elliman 《Applied Physics A: Materials Science & Processing》2012,107(3):749-754
Silica nanowires, grown via the active oxidation of a silicon substrate, have been coated with TiO2 using two coating methods: solution-based deposition of Ti-alkoxides and atomic layer deposition. Analysis of as-deposited and annealed films shows that it is possible to produce stable conformal coatings of either the anatase or rutile phases of TiO2 on nanowires with diameters greater than 100 nm when annealed between 500–600°C and 800–900°C, respectively, with annealing at higher temperatures (1050°C) producing coatings with a highly facetted rutile morphology. The efficacy of the process is shown to depend on nanowire diameter, with nanowires having diameters less than about 100 nm fusing together during solution-based coating and decomposing during TiO2 atomic layer deposition. The use of a suitable buffer layer is shown to be an effective means of minimizing nanowire decomposition. Finally, annealing coated nanowires under active oxidation conditions (1100°C) is shown to be an effective technique for depositing additional conformal SiO x coatings, thereby providing a means of fabricating multi-layered coaxial nanostructures. 相似文献
87.
An optical encryption method based on a geometrical phase produced by space-variant polarization manipulation is presented. The decrypted picture is retrieved either by a polarization measurement of the beam emerging from the encrypted element or by a single intensity measurement of the beam transmitted through the encrypted element followed by an optical key element. Both elements are realized by use of computer-generated space-variant subwavelength dielectric gratings. Theoretical analyses of the optical concept are presented along with experimental results. 相似文献
88.
89.
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
90.
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