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11.
We use Zimm's single-contact approximation to investigate the concentration dependence of the first cumulant for partially labeled chains in dilute solutions. This approximation allows us to express interchain properties (such as the interference part of the generalized mobility) in terms of static structure factors, which are then modeled using a Gaussian chain model. We present numerical results for three specific labeling sequences. 相似文献
12.
Rossi P Mirazita M Ronchetti F De Sanctis E Adams G Ambrozewicz P Anciant E Anghinolfi M Asavapibhop B Audit G Avakian H Bagdasaryan H Ball JP Barrow S Battaglieri M Beard K Bektasoglu M Bellis M Benmouna N Berman BL Bertozzi W Bianchi N Biselli AS Boiarinov S Bonner BE Bouchigny S Bradford R Branford D Briscoe WJ Brooks WK Burkert VD Butuceanu C Calarco JR Carman DS Carnahan B Chen S Cole PL Cords D Corvisiero P Crabb D Crannell H Cummings JP De Vita R Degtyarenko PV Denizli H Dennis L 《Physical review letters》2005,94(1):012301
13.
Stavinsky AV Mikhailov KR Lednicky R Vlassov AV Adams G Ambrozewich P Anciant E Anghinolfi M Asavapibhop B Asryan G Audit G Auger T Avakian H Bagdasaryan H Ball JP Barrow S Batourine V Battaglieri M Beard K Bektasoglu M Bellis M Benmouna N Bianchi N Biselli AS Boiarinov S Bonner BE Bouchigny S Bradford R Branford D Brooks WK Burkert VD Butuceanu C Calarco JR Carman DS Cetina C Chen S Cole PL Cords D Coleman A Corvisiero P Crabb D Cummings JP Dashyan N Sanctis ED Vita RD Degtyarenko PV Denizli H 《Physical review letters》2004,93(19):192301
Two-proton correlations at small relative momentum q were studied in the eA(3He,4He,C,Fe)-->e(')ppX reaction at E(0)=4.46 GeV using the CLAS detector at Jefferson Lab. The enhancement of the correlation function at small q was found to be in accordance with theoretical expectations. Sizes of the emission region were extracted, and proved to be dependent on A and on the proton momentum. The size of the two-proton emission region for He was measured in eA reactions for the first time. 相似文献
14.
Let P=(P
t
)
t>0 be a submarkovian semigroup of kernels on a measurable space (X,). An additive kernel of P is a kernel K from X into ]0,[ such that P
t
K(x,A)=K(x,A+t) for every t>0,xX and every Borel subset A of ]0,[. It is proved in this paper that for every potential f of P, there exits an additive kernel K of P, unique (up to equivalence) such that f=K1=0
K(,dt). This result is already well known for regular potentials of right processes. If U=(U
p
)
p>0 is a sub-Markovian resolvent of kernels on (X,), we give a notion of additive kernel of U and we prove a similar integral representation of potentials of U. 相似文献
15.
Diffusion of 111In/Cd impurity atoms was studied in Ga7Pt3 at the atomic level using the method of perturbed angular correlation of gamma rays (PAC). As in previous measurements on Ga7Pd3, probes were observed to occupy two inequivalent Ga-sublattices. Quadrupole interaction perturbation functions for each site exhibited damping at elevated temperatures that is attributed to nuclear relaxation caused by stochastic jumps of the probe atoms accompanied by reorientation of axes of the electric field gradient tensor. Fitted relaxation frequencies, proportional to mean jump frequencies of the probe, were thermally activated. Arrhenius plots revealed jump-frequency activation enthalpies of 0.94 (8) and 0.67 (4) eV for the two sites and frequency prefactors close to 1 THz. Results were similar to those found previously for Ga7Pd3, although jump frequencies are about 100 times lower in Ga7Pt3. 相似文献
16.
Maciej Garbarczyk Farida Grinberg Nikolaus Nestle Winfried Kuhn 《Journal of Polymer Science.Polymer Physics》2001,39(18):2207-2216
We present a novel NMR approach to the determination of crosslink densities in rubber materials. The method is based on the dipolar correlation effect (DCE) on the stimulated echo examined in a series of rubber samples and linear polyisoprene. The parameter evaluated from the echo attenuation curves is the mean‐squared dipolar fluctuation associated with anisotropic reorientations of macromolecular backbones. The contributions to the DCE of the constraints due to excluded volume effects and chemical crosslinks are estimated. A strong dependence of the mean‐squared dipolar fluctuation on the crosslink density of rubber combined with the simplicity of performing the measurements with inexpensive low‐field instruments suggests that the DCE is a useful tool for routine applications. The potential and problems of performing DCE measurements in low‐magnetic‐field conditions are discussed in detail. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2207–2216, 2001 相似文献
17.
Navasardyan T Adams GS Ahmidouch A Angelescu T Arrington J Asaturyan R Baker OK Benmouna N Bertoncini C Blok HP Boeglin WU Bosted PE Breuer H Christy ME Connell SH Cui Y Dalton MM Danagoulian S Day D Dodario T Dunne JA Dutta D El Khayari N Ent R Fenker HC Frolov VV Gan L Gaskell D Hafidi K Hinton W Holt RJ Horn T Huber GM Hungerford E Jiang X Jones M Joo K Kalantarians N Kelly JJ Keppel CE Kubarovski V Li Y Liang Y Malace S Markowitz P McGrath E McKee P Meekins DG Mkrtchyan H Moziak B 《Physical review letters》2007,98(2):022001
A large data set of charged-pion (pi+/-) electroproduction from both hydrogen and deuterium targets has been obtained spanning the low-energy residual-mass region. These data conclusively show the onset of the quark-hadron duality phenomenon, as predicted for high-energy hadron electroproduction. We construct several ratios from these data to exhibit the relation of this phenomenon to the high-energy factorization ansatz of electron-quark scattering and subsequent quark-->pion production mechanisms. 相似文献
18.
Dr. Lucy Clark Dr. Farida H. Aidoudi Dr. Cameron Black Dr. Kasun S. A. Arachchige Prof. Dr. Alexandra M. Z. Slawin Prof. Dr. Russell E. Morris Prof. Dr. Philip Lightfoot 《Angewandte Chemie (International ed. in English)》2015,54(51):15457-15461
The ionothermal synthesis, structure, and magnetic susceptibility of a novel inorganic–organic hybrid material, imidazolium vanadium(III,IV) oxyfluoride [C3H5N2][V9O6F24(H2O)2] (ImVOF) are presented. The structure consists of inorganic vanadium oxyfluoride slabs with kagome layers of V4+ S=${{ 1/2 }}$ ions separated by a mixed valence layer. These inorganic slabs are intercalated with imidazolium cations. Quinuclidinium (Q) and pyrazinium (Pyz) cations can also be incorporated into the hybrid structure type to give QVOF and PyzVOF analogues, respectively. The highly frustrated topology of the inorganic slabs, along with the quantum nature of the magnetism associated with V4+, means that these materials are excellent candidates to host exotic magnetic ground states, such as the highly sought quantum spin liquid. Magnetic susceptibility measurements of all samples suggest an absence of conventional long‐range magnetic order down to 2 K despite considerable antiferromagnetic exchange. 相似文献
19.
New polystyrene-supported 4-amino pyridines are described. Some of them exhibit a good catalytic activity in acylation reactions. 相似文献
20.
We consider the variation of the coherent elastic scattering structure factor S(q) with momentum transfer q for a solution of block copolymers at finite concentration. We introduce the effect of concentration using a generalization of Zimm's model to copolymers which enables us to express intermolecular scattering functions in terms of intramolecular form factors only. We show that the shape of the scattering curve is very sensitive to the polymer concentration as well as to the contrast factors, the relative composition of co units, and the second virial coefficients characterizing constituents of the copolymer. In particular, we show that the scattering curve develops a maximum at low q for certain values of these parameters. We also discuss the variation of the apparent radius of gyration with polymer concentration. 相似文献