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21.
A thermodynamically guided atomistic Monte Carlo methodology is presented for simulating systems beyond equilibrium by expanding the statistical ensemble to include a tensorial variable accounting for the overall structure of the system subjected to flow. For a given shear rate, the corresponding tensorial conjugate field is determined iteratively through independent nonequilibrium molecular dynamics simulations. Test simulations for the effect of flow on the conformation of a C50H102 polyethylene liquid show that the two methods (expanded Monte Carlo and nonequilibrium molecular dynamics) provide identical results. 相似文献
22.
Fong-Fu Hsu Irfan J. Lodhi John Turk Clay F. Semenkovich 《Journal of the American Society for Mass Spectrometry》2014,25(8):1412-1420
We describe a linear ion-trap (LIT) multiple-stage (MSn) mass spectrometric approach towards differentiation of alkylacyl, alk-1-enylacyl- and diacyl-glycerophoscholines (PCs) as the [M – 15]– ions desorbed by electrospray ionization (ESI) in the negative-ion mode. The MS4 mass spectra of the [M – 15 – R2′CH = CO]– ions originated from the three PC subfamilies are readily distinguishable, resulting in unambiguous distinction of the lipid classes. This method is applied to two alkyl ether rich PC mixtures isolated from murine bone marrow neutrophils and kidney, respectively, to explore its utility in the characterization of complex PC mixture of biological origin, resulting in the realization of the detailed structures of the PC species, including various classes and many minor isobaric isomers. Graphical abstract
? 相似文献
23.
Meirong Hu Xue Zhou Yiping Shi Jianhui Lin Muhammad Irfan Yong Tao 《Applied biochemistry and biotechnology》2014,174(5):2007-2017
POXA1b is the most thermostable laccase isoenzyme from Pleurotus ostreatus. POXA1b is remarkably stable at alkaline pH (the t1/2 at pH 10 was 30 days), and its C-terminal affects its catalytic and stability properties. We cloned POXA1c from P. florida, which showed 99 % identity with POXA1b. POXA1c was functionally expressed in Pichia pastoris. The functions of the N and C termini of POXA1c were investigated using site-directed mutagenesis. Compared with POXA1c, the N-terminal R5V site effectively increased the specific activities for 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and guaiacol by 2- and 3.5-fold, respectively. A C-terminal truncated mutant, POXA1c△13, also increased the specific activities for ABTS and guaiacol by 2.3- and 3.4-fold, respectively. A double mutant, POXA1cΔ13-R5V, combined the R5V and △13 effects. The specific activity of this double mutant for ABTS was 1,321 U/mg, which indicated a 4-fold increase compared with the wild type. The role of residue V5 on laccase catalytic properties was also observed for laccases from Trametes versicolor and Rigidoporus lignosus. The specific activities of the V5R of the laccases from T. versicolor and R. lignosus were half of that of the wild type. The pH and thermal stability analysis of POXA1c and its mutants showed that the enzymes were remarkably stable because they showed 63 % residual activity after incubation for 108 h at 30 °C over a pH range of 4.5 to 9.0. Similar results were observed for POXA1cΔ13-R5V. POXA1cΔ13-R5V can be widely used in industrial biotechnology because of its excellent catalytic properties. 相似文献
24.
Atta-Ur-Rahman Nasim S Baig I Ara Jahan I Sener B Orhan I Choudhary MI 《Chemical & pharmaceutical bulletin》2002,50(8):1100-1102
Four isoflavone glycosides were isolated from the rhizomes of Iris germanica. Compounds 1 and 2 are new, while compounds 3 and 4 are known isoflavone glycosides. These compounds were identified as iriskashmirianin 4'-O-beta-D-glucoside (1), nigricin 4'-O-beta-D-glucoside (2), irilone 4'-O-beta-D-glucoside (3) and iridin (4). Their structures were determined with the help of spectroscopic methods. 相似文献
25.
The absorption spectra of7LiH have been photographed in the 3,500?2,900 Å region using the second order of a 3.4 M Ebert spectrograph. Observations comprise previously observedA 1 Σ +-X 1 Σ + transitions and several new vibrational bands of this system near the ionisation limit. Rotational and vibrational analysis of these bands (16≦V′≦20) have been carried out and the rotational constants for the upper states have been determined. 相似文献
26.
Multiparticle production data on proton-nucleus collisions have been analyzed taking the number of ‘created’ charged particles
instead of the observed number of shower particles as the variable. The mean normalized multiplicity,R
A
, has been found to be independent of energy in the energy range (7–8000) GeV and its mass number dependence has been obtained.
The modified analysis introduces some more regularities in the experimental results onp-nucleus collisions like the invariance with respect to energy of the relationshipR
A
= α + βN
h
and the KNO-like scaling of the multiplicity distributions of the created charged particles. The functional form of the scaling
function has been calculated. 相似文献
27.
We demonstrate how to create artificial external non-Abelian gauge potentials acting on cold atoms in optical lattices. The method employs atoms with k internal states, and laser assisted state sensitive tunneling, described by unitary k x k matrices. The single-particle dynamics in the case of intense U2 vector potentials lead to a generalized Hofstadter butterfly spectrum which shows a complex mothlike structure. We discuss the possibility to realize non-Abelian interferometry (Aharonov-Bohm effect) and to study many-body dynamics of ultracold matter in external lattice gauge fields. 相似文献
28.
Choudhary MI Nur-E-Alam M Akhtar F Ahmad S Baig I Ondögnii P Gombosurengyin P Atta-ur-Rahman 《Chemical & pharmaceutical bulletin》2001,49(10):1295-1298
Five new peltogynoids, irisoids A-E (1-5), have been isolated from the underground parts of Iris bungei. The structures of the new compounds were established on the basis of spectroscopic methods and were found to be 1,8,10-trihydroxy-9-methoxy-[1]benzopyrano-[3,2-c][2]-benzopyran-7(5H)-one (1), 1,8-dihydroxy-9,10-dimethoxy-[1]benzopyrano-[3,2-c][2]-benzopyran-7(5H)-one (2), 1,10-dihydroxy-8,9-dimethoxy-[1]benzopyrano-13,2-c][2]-benzopyran-7(5H)-one (3), 1,8-dihydroxy-9,10-methylenedioxy-[1]benzopyrano-[3,2-c][2]-benzopyran-7(5H)-one (4), and 1,8,11-trihydroxy-9,10-methylenedioxy-[1]benzopyrano-[3,2-c][2]-benzopyran-7(5H)-one (5). The structure of irisoid B (2) was established unambiguously by X-ray diffraction study. 相似文献
29.
One of the most important problems of coding theory is to constructcodes with best possible minimum distances. In this paper, we generalize the method introduced by [8] and obtain new codes which improve the best known minimum distance bounds of some linear codes. We have found a new linear ternary code and 8 new linear codes over
with improved minimumdistances. First we introduce a generalized version of Gray map,then we give definition of quasi cyclic codes and introduce nearlyquasi cyclic codes. Next, we give the parameters of new codeswith their generator matrices. Finally, we have included twotables which give Hamming weight enumerators of these new codes. 相似文献
30.
Quantum states can be used to encode the information contained in a direction, i.e., in a unit vector. We present the best encoding procedure when the quantum state is made up of N spins (qubits). We find that the quality of this optimal procedure, which we quantify in terms of the fidelity, depends solely on the dimension of the encoding space. We also investigate the use of spatial rotations on a quantum state, which provide a natural and less demanding encoding. In this case we prove that the fidelity is directly related to the largest zeros of the Legendre and Jacobi polynomials. We also discuss our results in terms of the information gain. 相似文献