Nonequilibrium model on Archimedean lattices

On (4, 6, 12) and (4, 8²) Archimedean lattices, the critical properties of the majority-vote model are considered and studied using the Glauber transition rate proposed by Kwak et al. [Kwak et al., Phys. Rev. E, 75, 061110 (2007)] rather than the traditional majority-vote with noise [Oliveira, J. Stat. Phys. 66, 273 (1992)]. We obtain T _c and the critical exponents for this Glauber rate from extensive Monte Carlo studies and finite size scaling. The calculated values of the critical temperatures and Binder cumulant are T _c = 0.651(3) and U ₄ ^* = 0.612(5), and T _c = 0.667(2) and U ₄ ^* = 0.613(5), for (4, 6, 12) and (4, 8²) lattices respectively, while the exponent (ratios) β/ν, γ/ν and 1/ν are respectively: 0.105(8), 1.48(11) and 1.16(5) for (4, 6, 12); and 0.113(2), 1.60(4) and 0.84(6) for (4, 8²) lattices. The usual Ising model and the majority-vote model on previously studied regular lattices or complex networks differ from our new results.     

Charge and substituent effects on the stability of porphyrin/G-quadruplex adducts

The adduct ions of two tetramolecular G-quadruplexes formed from the d(TGGGGT) and d(TTGGGGGT) single strands with a group of cationic porphyrins, with different charges and substituents, and one neutral porphyrin, were investigated by ESI-MS and ESI-MS/MS in the negative ion mode. Formation of [Q + nNH(4)(+)+P(p+)-(z + n + p)H(+)](z-) adduct ions (where Q = quadruplex, n = number of quartets minus 1, P = porphyrin and p(+) = 0,1,2,3,4) indicates that the porphyrins are bound outside the quadruplexes providing an additional stabilization to those structures. The fragmentation pathways of the [Q + nNH(4)(+)+P(p+)-(z + n + p)H(+)](z-) adduct ions depend on the number of positive charges (p(+)) of the porphyrins and on the overall complex charge (z(-)), but do not show a significant dependence on the type of the substituent groups in the porphyrins. Formation of the 'unfilled' ions [Q + P(p+)-(z + p)H(+)](z-) predominates for porphyrins with a higher number of positive charges. Strand separation with the formation of [T + P(p+)-(z-2 + p)H(+)]((z-2)-) and (SS-2H(+))(2-) ions, where T = [d(TG(4)T)](3) and [d(T(2)G(5)T)](3) and SS = d(TG(4)T) and d(T(2)G(5)T) is only observed for the complexes with a higher overall negative charge. Porphyrin loss with the formation of [Q + nNH(4)(+)-(z + n)H(+)](z-) ions occurs predominantly for the neutral and monocharged porphyrins. The predominant formation of the 'unfilled' ions, [Q + P(p+)-(z + n)H(+)](z-), for porphyrins with a higher number of charges shows that these porphyrins can prevent strand separation and preserve, at least partially, the quadruplex structure.     

Cluster analysis and finite-size scaling for Ising spin systems

Based on the connection between the Ising model and a correlated percolation model, we calculate the distribution function for the fraction (c) of lattice sites in percolating clusters in subgraphs with n percolating clusters, f(n)(c), and the distribution function for magnetization (m) in subgraphs with n percolating clusters, p(n)(m). We find that f(n)(c) and p(n)(m) have very good finite-size scaling behavior and that they have universal finite-size scaling functions for the model on square, plane triangular, and honeycomb lattices when aspect ratios of these lattices have the proportions 1:square root[3]/2:square root[3]. The complex structure of the magnetization distribution function p(m) for the system with large aspect ratio could be understood from the independent orientations of two or more percolation clusters in such a system.     

Entropic rigidity of randomly diluted two- and three-dimensional networks

In recent work, we presented evidence that site-diluted triangular central-force networks, at finite temperatures, have a nonzero shear modulus for all concentrations of particles above the geometric percolation concentration p(c). This is in contrast to the zero-temperature case where the (energetic) shear modulus vanishes at a concentration of particles p(r)>p(c). In the present paper we report on analogous simulations of bond-diluted triangular lattices, site-diluted square lattices, and site-diluted simple-cubic lattices. We again find that these systems are rigid for all p>p(c) and that near p(c) the shear modulus mu approximately (p-p(c))(f), where the exponent f approximately 1.3 for two-dimensional lattices and f approximately 2 for the simple-cubic case. These results support the conjecture of de Gennes that the diluted central-force network is in the same universality class as the random resistor network. We present approximate renormalization group calculations that also lead to this conclusion.     

Universality class of criticality in the restricted primitive model electrolyte

The 1:1 equisized hard-sphere electrolyte or restricted primitive model has been simulated via grand-canonical fine-discretization Monte Carlo. Newly devised unbiased finite-size extrapolation methods using loci in the temperature-density or (T,rho) plane of isothermal rho(2-k) vs pressure inflections, of Q identical with(2)/ maxima, and of canonical and C(V) criticality, yield estimates of (T(c),rho(c)) to +/-(0.04,3)%. Extrapolated exponents and Q ratio are (gamma,nu,Q(c)) = [1.24(3), 0.63(3); 0.624(2)], which support Ising (n = 1) behavior with (1.23(9), 0.630(3); 0.623(6)), but exclude classical, XY (n = 2), self-avoiding walk (n = 0), and n = 1 criticality with potentials varphi(r)>Phi/r(4.9) when r-->infinity.     

Elliptic flow of identified hadrons in Au+Au collisions at sqrt sNN =200 GeV

The anisotropy parameter (v(2)), the second harmonic of the azimuthal particle distribution, has been measured with the PHENIX detector in Au+Au collisions at sqrt[s(NN)]=200 GeV for identified and inclusive charged particle production at central rapidities (|eta|<0.35) with respect to the reaction plane defined at high rapidities (|eta|=3-4 ). We observe that the v(2) of mesons falls below that of (anti)baryons for p(T)>2 GeV/c, in marked contrast to the predictions of a hydrodynamical model. A quark-coalescence model is also investigated.     

含ME4(M＝Mo,W;E＝S,Se)单元簇合物的合成和红外谱表征

合成了一系列单立方烷Ｍ－Ｆｅ－Ｓｅ和Ｍ－Ｃｕ（Ａｇ）－Ｓ（Ｓｅ）簇合物,并用ＵＶ,ＩＲ和Ｘ－光衍射等方法对上述簇合物进行了分析。     

Linking numbers for self-avoiding loops and percolation: application to the spin quantum hall transition

Nonlocal twist operators are introduced for the O(n) and Q-state Potts models in two dimensions which count the numbers of self-avoiding loops (respectively, percolation clusters) surrounding a given point. Their scaling dimensions are computed exactly. This yields many results: for example, the number of percolation clusters which must be crossed to connect a given point to an infinitely distant boundary. Its mean behaves as (1/3sqrt[3] pi) |ln( p(c)-p)| as p-->p(c)-. As an application we compute the exact value sqrt[3]/2 for the conductivity at the spin Hall transition, as well as the shape dependence of the mean conductance in an arbitrary simply connected geometry with two extended edge contacts.     

Peptide internal motions on nanosecond time scale derived from direct fitting of (13)C and (15)N NMR spectral density functions

NMR relaxation-derived spectral densities provide information on molecular and internal motions occurring on the picosecond to nanosecond time scales. Using (13)C and (15)N NMR relaxation parameters [T(1), T(2), and NOE] acquired at four Larmor frequencies (for (13)C: 62.5, 125, 150, and 200 MHz), spectral densities J(0), J(omega(C)), J(omega(H)), J(omega(H) + omega(C)), J(omega(H) - omega(C)), J(omega(N)), J(omega(H) + omega(N)), and J(omega(H) - omega(N)) were derived as a function of frequency for (15)NH, (13)C(alpha)H, and (13)C(beta)H(3) groups of an alanine residue in an alpha-helix-forming peptide. This extensive relaxation data set has allowed derivation of highly defined (13)C and (15)N spectral density maps. Using Monte Carlo minimization, these maps were fit to a spectral density function of three Lorentzian terms having six motional parameters: tau(0), tau(1), tau(2), c(0), c(1), and c(2), where tau(0), tau(1) and tau(2) are correlation times for overall tumbling and for slower and faster internal motions, and c(0), c(1), and c(2) are their weighting coefficients. Analysis of the high-frequency portion of these maps was particularly informative, especially when deriving motional parameters of the side-chain methyl group for which the order parameter is very small and overall tumbling motions do not dominate the spectral density function. Overall correlation times, tau(0), are found to be in nanosecond range, consistent with values determined using the Lipari-Szabo model-free approach. Internal motional correlation times range from picoseconds for methyl group rotation to nanoseconds for backbone N-H, C(alpha)-H, and C(alpha)-C(beta) bond motions. General application of this approach will allow greater insight into the internal motions in peptides and proteins.     

疏水性离子液体萃取-原子吸收光谱法分离分析微量金

以N-甲基咪唑和溴代正丁烷及六氟磷酸铵合成了疏水性离子液体1-丁基-3-甲基咪唑六氟磷酸盐([Bmim][PF6])。运用该离子液体分离富集分析了微量金。以火焰原子吸收光谱法(FAAS)为分析检测手段,探讨了离子液体萃取预富集微量金的条件。实验结果表明:金的浓度在0.40～16.00μg·mL-1范围内与吸光度成线性关系,线性方程为A=0.00763c+0.07387(c:μg·mL-1),r=0.9991,检测限为0.072μg·mL-1。该法用于样品测定结果令人满意。     

Centrality dependence of pi(+/-), K(+/-), p,and (-)p production from sqrt[s(NN)] = 130 GeV Au + Au collisions at RHIC

Identified pi(+/-), K(+/-), p, and (-)p transverse momentum spectra at midrapidity in sqrt[s(NN)] = 130 GeV Au+Au collisions were measured by the PHENIX experiment at RHIC as a function of collision centrality. Average transverse momenta increase with the number of participating nucleons in a similar way for all particle species. Within errors, all midrapidity particle yields per participant are found to be increasing with the number of participating nucleons. There is an indication that K(+/-), p, and (-)p yields per participant increase faster than the pi(+/-) yields. In central collisions at high transverse momenta (p(T) > or =2 GeV/c), (-)p and p yields are comparable to the pi(+/-) yields.     

Sharply Dominating MV-Effect Algebras

Some open questions on Archimedean atomic MV-effect algebras are answered. Namely we prove that there are Archimedean atomic MV-effect algebras which are not sharply dominating. Equivalently, they don’t have a basic decomposition of elements. Moreover, if their set of sharp elements (their center) is a complete lattice then they need not be complete lattices. The existence of infinite orthogonal sums of their elements is discussed.     

S-layers on cell walls of cyanobacteria.

S-layers are surface layers of bacterial cell walls. They are formed by two-dimensional, monomolecular crystalline arrays of identical units of protein or glycoprotein macromolecules (subunits). In general, each S-layer exhibits one of four possible 2-D lattice types: oblique (p1 or p2 symmetry), triangle (p3 symmetry), square (p4 symmetry) or hexagonal (p6 symmetry). The S-layer protein compasses up to 15% of the total protein of the bacterial cell and thus represents its major protein.Since 1972, S-layers have also been found in cyanobacteria. So far, they have been observed in 60 strains (isolates) of 23 species, belonging to 12 genera of unicellular Chroococcales and in just five strains or isolates (four species, four genera-only with p1 and p4 lattice symmetry) of filamentous Oscillatoriales; in further families of filamentous cyanobacteria (Nostocales, Stigonematales) they have not been detected, although filamentous cyanobacteria have been frequently studied in the electron microscope. In Chroococcales, relatively large cells of planktonic genera harbouring gas vesicles, S-layers are often present, while picoplanktonic species without gas vesicles usually do not have them.The p6 lattice symmetry appears to be the most common in cyanobacteria, having been found in 41 out of the 60 S-layers observed. All cells of a given strain, all strains capable of forming S-layers and all S-layer forming species of a given genus (as far as it is known) form S-layers of the same lattice type. Hence, the ability to form an S-layer appears to be useful as a supportive morphological marker for species classification.In 41 S-layer formers, the center-to-center spacing of their lattice unit arrays has been measured; the lattice constants range from 5 to 22nm, measured directly on surface of fixed cells. Coarse S-layers of p6 symmetry are the most frequent (with spacing of 15.0-22.0nm); p1 and p2 S-layers are the finest ones (with spacing of 5.0-10.0nm). Medium-spaced lattices (11.0-14.0nm) may be both of the p4 or p6 symmetry types. When measured on isolated S-layers, the spacings show a 10-60% higher value.All the hexagonal unit lattices have the same molecular architecture. Each S-layer unit resembles a truncated cone with an axial pore and with six protein subunits symmetrically placed around its opening. Adjoining units are interspaced by relatively fine channels. The fine detail of every S-layer of every individual strain is unique.Only the S-layer protein subunits of Synechococcus sp. strain GL24 have been analysed by electrophoresis. When incorporated into the S-layer units they confer a net neutral charge to the cell surface. This cyanobacterium induces mineralization of fine-grain gypsum and calcite in a saturated lake fresh water solution. This process is involved in the formation of stromatolites.     

Suppressed pi(0) production at large transverse momentum in central Au+Au collisions at sqrt[s(NN)]=200 GeV

Transverse momentum spectra of neutral pions in the range 1相似文献   

Laser ablation synthesis of new gold phosphides using red phosphorus and nanogold as precursors. Laser desorption ionisation time-of-flight mass spectrometry

Gold phosphides show unique optical or semiconductor properties and there are extensive high technology applications, e.g. in laser diodes, etc. In spite of the various AuP structures known, the search for new materials is wide. Laser ablation synthesis is a promising screening and synthetic method. Generation of gold phosphides via laser ablation of red phosphorus and nanogold mixtures was studied using laser desorption ionisation time-of-flight mass spectrometry (LDI TOFMS). Gold clusters Au(m)(+) (m?=?1 to ~35) were observed with a difference of one gold atom and their intensities were in decreasing order with respect to m. For P(n)(+) (n?=?2 to ~111) clusters, the intensities of odd-numbered phosphorus clusters are much higher than those for even-numbered phosphorus clusters. During ablation of P-nanogold mixtures, clusters Au(m)(+) (m?=?1-12), P(n)(+) (n?=?2-7, 9, 11, 13-33, 35-95 (odd numbers)), AuP(n)(+) (n?=?1, 2-88 (even numbers)), Au(2)P(n)(+) (n?=?1-7, 14-16, 21-51 (odd numbers)), Au(3)P(n)(+) (n?=?1-6, 8, 9, 14), Au(4)P(n)(+) (n?=?1-9, 14-16), Au(5)P(n)(+) (n?=?1-6, 14, 16), Au(6)P(n)(+) (n?=?1-6), Au(7)P(n)(+) (n?=?1-7), Au(8)P(n)(+) (n?=?1-6, 8), Au(9)P(n)(+) (n?=?1-10), Au(10)P(n)(+) (n?=?1-8, 15), Au(11)P(n)(+) (n?=?1-6), and Au(12)P(n)(+) (n?=?1, 2, 4) were detected in positive ion mode. In negative ion mode, Au(m)(-) (m?=?1-5), P(n)(-) (n?=?2, 3, 5-11, 13-19, 21-35, 39, 41, 47, 49, 55 (odd numbers)), AuP(n)(-) (n?=?4-6, 8-26, 30-36 (even numbers), 48), Au(2)P(n)(-) (n?=?2-5, 8, 11, 13, 15, 17), A(3) P(n)(-) (n?=?6-11, 32), Au(4)P(n)(-) (n?=?1, 2, 4, 6, 10), Au(6)P(5)(-), and Au(7)P(8)(-) clusters were observed. In both modes, phosphorus-rich Au(m)P(n) clusters prevailed. The first experimental evidence for formation of AuP(60) and gold-covered phosphorus Au(12)P(n) (n?=?1, 2, 4) clusters is given. The new gold phosphides generated might inspire synthesis of new Au-P materials with specific properties.     

Rovibrational Analysis of the nu(2) Band of Diazirine-d(2)

The gas-phase IR spectrum of the nu(2) (A(1), 1610.33 cm(-1)) band of the deuterated isotopomer of diazirine, D(2)CN(2), a three-membered ring compound which belongs to the molecular symmetry point group C(2v), has been studied at a resolution of about 0.005 cm(-1). This vibrational mode which can be approximately described as N&dbond;N stretching is widely perturbed. This is due to various interactions with the tetrad consisting of the binary combinations nu(6) + nu(7) (A(1)), nu(7) + nu(9) (A(2)), nu(5) + nu(6) (B(2)), and nu(5) + nu(9) (B(1)), which form a relatively isolated pentad together with nu(2) in the wavenumber region 1560-1610 cm(-1). A simultaneous upper state analysis of nu(2) from a pentad model including these resonances has been performed and a set of spectroscopic parameters has been obtained. Since the four combination bands of the pentad are dark states, only band centers could be determined; in addition for nu(5) + nu(9) and nu(7) + nu(9) also the term (B - C)/2 has been obtained. A number of Coriolis interaction constants and the vibrational resonance (with nu(6) + nu(7)) parameter have been calculated as well. Copyright 2001 Academic Press.     

掺杂三价铽离子的碱土金属钨酸盐的光谱特性研究

本文合成了一系列掺杂三价铽离子的碱土金属钨酸盐,测定了晶体的X射线粉末衍射数据及发射光谱和激发光谱.所合成的化合物均属四方晶系,I41/a空间群,晶胞多数随金属离子半径的增大而增大.研究了在这些晶体中三价铽离子5D3→7Fi和5D4→7Fi跃迁发射的激发态及其能量传递机理和浓度猝灭机制.讨论了发射光谱和激发光谱与铽离子浓度、金属离子半径及铽离子在晶体中的溶解度的关系.     

The Landau gauge gluon propagator in lattice QCD

A Monte Carlo calculation of the gluon propagator in the Landau gauge in SU(3) lattice gauge theory is described. The results of calculations at β = 5.6 (200 4³ × 8 lattices), β = 5.8 (400 4³ × 10 lattices and 100 6³ × 12 lattices), and β = 6.0 (100 4³ × 8 lattices) indicate that the gluon propagator resembles a massive particle propagator in which the mass grows with separation. At the largest distances accessible with these lattices, the mass is about 600 MeV.     

Relaxation length of a polymer chain in a quenched disordered medium

Using Monte Carlo simulations, we study the relaxation and short-time diffusion of polymer chains in two-dimensional periodic arrays of obstacles with random point defects. The displacement of the center of mass follows the anomalous scaling law r(c.m.)(t)(2)=4D(*)t(beta), with beta<1, for times t相似文献   

Observation of inverse diproton photodisintegration at intermediate energies

The fundamental reaction pp-->{pp}_{s}gamma, where {pp}_{s} is a proton pair with low excitation energy, has been observed with the ANKE spectrometer at COSY-Jülich for proton beam energies of T_{p}=0.353, 0.500, and 0.550 GeV. This is equivalent to photodisintegration of a free 1S0 diproton for photon energies E_{gamma} approximately T_{p}/2. The differential cross sections measured for c.m. angles 0 degrees gammad is on the 10;{-3}-10;{-2} level. The increase of the pp-->{pp}_{s}gamma cross section with T_{p} might reflect the influence of the Delta(1232) excitation.