Electron-nuclear entanglement in the cold lithium gas

We study the ground-state entanglement and thermal entanglement in the hyperfine interaction of the lithium atom. We give the relationship between the entanglement and both temperature and external magnetic fields.Comment: 7 pages, 3 figure

A PAGERANK-BASED MINING ALGORITHM FOR USER INFLUENCES ON MICRO-BLOGS

With the development of Web technology, the Micro-Blog has become one of the most popular social platforms, and calculating and ranking the influences of the users on Micro-Blogs has been issuing an important research problem. Through improving the traditional the PageRank model, this paper presents a called PR4MB (PageRank for Micro-Blog) algorithm, which can obviously improve mining precisions for evaluating user influences on a Micro-Blog. While considering user link relations like the PageRank method, the PR4MB algorithm also takes attention to the activity, quality and credibility of a user on a Micro-Blog, so it constructs a dynamic mining model for user influences on a Micro-Blog by evaluation user online behaviors. The experimental results show that PR4MB algorithm, in comparing with the traditional PageRank algorithm, can more truly reflects the actual influences of different users on a Micro-Blog

2-Amino-6-(naphthalen-1-yl)-4-phenyl­pyridine-3-carbonitrile

In the title compound, C22H15N3, the naphthyl ring system makes dihedral angles of 67.40 (2) and 59.80 (3)° with the pyridyl and phenyl rings, respectively. In the crystal, the mol­ecules are connected via inter­molecular N—H⋯N hydrogen bonds, forming a three-dimensional network

New spectrum of negative-parity doubly charmed baryons: Possibility of two quasistable states

The discovery of $\Xi_{cc}^{++}$ by the LHCb Collaboration triggers predictions of more doubly charmed baryons. By taking into account both the $P$-wave excitations between the two charm quarks and the scattering of light pseudoscalar mesons off the ground state doubly charmed baryons, a set of negative-parity spin-1/2 doubly charmed baryons are predicted already from a unitarized version of leading order chiral perturbation theory. Moreover, employing heavy antiquark-diquark symmetry the relevant low-energy constants in the next-to-leading order are connected with those describing light pseudoscalar mesons scattering off charmed mesons, which have been well determined from lattice calculations and experimental data. Our calculations result in a spectrum richer than that of heavy mesons. We find two very narrow $J^P=1/2^-$ $\Omega_{cc}^P$, which very likely decay into $\Omega_{cc}\pi^0$ breaking isospin symmetry. In the isospin-1/2 $\Xi_{cc}^P$ sector, three states are predicted to exist below 4.2~GeV with the lowest one being narrow and the other two rather broad. We suggest to search for the $\Xi_{cc}^{P}$ states in the $\Xi_{cc}^{++}\pi^-$ mode. Searching for them and their analogues are helpful to establish the hadron spectrum.Comment: 6 pages, 3 figures; accepted for publication as a Rapid Communication in Physical Review

Sensor placement in the noise source identification based on acoustic radiation modes

The noise source identification technology based on acoustic radiation modes could identify the noise source under less measuring points, while the sensor placement has great influence on the result of noise source identification. Under the prescribed number of sensors, a method to configure the measuring points is proposed. By the means of successive removal, select a set of measuring points in the candidate field points, which make the orthogonality of the acoustic field distribution modes matrix achieve the maximum value. The results of numerical simulation and sound box experiment have shown that when sensors are arranged in accordance with the measuring points selected by this method, the noise source could be identified effectively, and the identification result is better than that when sensors are arranged evenly

Quantitative evaluation of protein–DNA interactions using an optimized knowledge-based potential

Computational evaluation of protein–DNA interaction is important for the identification of DNA-binding sites and genome annotation. It could validate the predicted binding motifs by sequence-based approaches through the calculation of the binding affinity between a protein and DNA. Such an evaluation should take into account structural information to deal with the complicated effects from DNA structural deformation, distance-dependent multi-body interactions and solvation contributions. In this paper, we present a knowledge-based potential built on interactions between protein residues and DNA tri-nucleotides. The potential, which explicitly considers the distance-dependent two-body, three-body and four-body interactions between protein residues and DNA nucleotides, has been optimized in terms of a Z-score. We have applied this knowledge-based potential to evaluate the binding affinities of zinc-finger protein–DNA complexes. The predicted binding affinities are in good agreement with the experimental data (with a correlation coefficient of 0.950). On a larger test set containing 48 protein–DNA complexes with known experimental binding free energies, our potential has achieved a high correlation coefficient of 0.800, when compared with the experimental data. We have also used this potential to identify binding motifs in DNA sequences of transcription factors (TF). The TFs in 79.4% of the known TF–DNA complexes have accurately found their native binding sequences from a large pool of DNA sequences. When tested in a genome-scale search for TF-binding motifs of the cyclic AMP regulatory protein (CRP) of Escherichia coli, this potential ranks all known binding motifs of CRP in the top 15% of all candidate sequences

catena-Poly[[[tetra­aqua­samarium(III)]-di-μ-isonicotinato-κ4 O:O′] chloride]

In the structure of the title compound, {[Sm(C6H4NO2)2(H2O)4]Cl}n, the unique SmIII atom lies on a crystallographic twofold axis and is eight-coordinated by four O atoms from four isonicotinate ligands and four water mol­ecules in a slightly distorted square-anti­prismatic coodination environment. The SmIII atoms are bridged by two carboxyl­ate groups of two isonicotinate ligands, forming an extended chain along the c-axis direction. These chains are cross-linked through hydrogen bonds, forming a three-dimensional framework, with channels which accommodate the chloride anions

Inhibition of DNA polymerase reactions by pyrimidine nucleotide analogues lacking the 2-keto group

To investigate the influence of the pyrimidine 2-keto group on selection of nucleotides for incorporation into DNA by polymerases, we have prepared two C nucleoside triphosphates that are analogues of dCTP and dTTP, namely 2-amino-5-(2′-deoxy-β-d-ribofuranosyl) pyridine-5′-triphosphate (d*CTP) and 5-(2′-deoxy-β-d-ribofuranosyl)-3-methyl-2-pyridone-5′-triphosphate (d*TTP) respectively. Both proved strongly inhibitory to PCR catalysed by Taq polymerase; d*TTP rather more so than d*CTP. In primer extension experiments conducted with either Taq polymerase or the Klenow fragment of Escherichia coli DNA polymerase I, both nucleotides failed to substitute for their natural pyrimidine counterparts. Neither derivative was incorporated as a chain terminator. Their capacity to inhibit DNA polymerase activity may well result from incompatibility with the correctly folded form of the polymerase enzyme needed to stabilize the transition state and catalyse phosphodiester bond formatio