Application of magnetic poly(styrene-glycidyl methacrylate) microspheres for immunomagnetic separation of bone marrow cells

Surface-functionalized magnetic poly(styrene-glycidyl methacrylate) (PS-GMA) microspheres were prepared and coupled with Sca-1 antibody for cell selection from murine bone marrow mononuclear cells (MNCs). Biotinylated Sca-1 antibody could be directly coupled to avidin-bound magnetic microspheres. Alternatively, oxidized goat anti-mouse antibody was covalently bound onto the amino group-containing magnetic microspheres in a site-directed manner, and the resultant conjugate was coupled with non-modified Sca-1 antibody. Using the indirect antibody-bound magnetic microspheres, the purity of isolated Sca-1⁺ cells increased with bead-to-cell ratio. Using a bead-to-cell ratio of 10 beads/cell, a purity of 85% Sca-1⁺ cells corresponding to a 17-fold enrichment was achieved.     

Hadronic Matrix Elements in the Cornell Potential Model

Using the relativized Cornell potential model and with some relativistic correction,we calculate the decay constants of pseudoscalar mesons and the B parameters of D⁰-D⁰ and B⁰-B⁰ systems.     

Exclusive semileptonicB decays in the bag model

Using a recoil corrected version of the MIT bag model, we compute the relevant form factors and decay rates for the exclusive semileptonic decays \(B \to De\bar v_e and B \to D*e\bar v_e \) . Our results are similar to other quark model calculations, but we find that theD ^* mode is suppressed due to the influence of the spectator quark. TheD ^*′ s produced are almost unpolarized in this model.     

VEGFR-2 targeted cellular delivery of doxorubicin by gold nanoparticles for potential antiangiogenic therapy

We report a novel gold nanobioconjugate system that achieves targeted delivery of the small molecule drug doxorubicin to endothelial cells using anti-VEGFR-2 antibody conjugated gold nanoparticles (GNPs). The reported nanobioconjugate system combines the inherent ability of GNPs to undergo high levels of derivatization with the precision of antibody recognition of a cell surface antigen. Transmission electron microscopy (TEM) and surface-enhanced Raman spectroscopy (SERS) confirmed intracellular presence of the GNPs. Using a VEGFR-2 expressing cell line and a cell line that is negative for the receptor, in combination with competition assay we established the cell specific targeted delivery of the nanobioconjugate. The nanobioconjugate system described here may have potential drug delivery applications for antiangiogenic cancer therapy.     

Phase transitions in a probabilistic cellular automaton: Growth kinetics and critical properties

We investigate a discrete-time kinetic model without detailed balance which simulates the phase segregation of a quenched binary alloy. The model is a variation on the Rothman-Keller cellular automaton in which particles of type A (B) move toward domains of greater concentration of A (B). Modifications include a fully occupied lattice and the introduction of a temperature-like parameter which endows the system with a stochastic evolution. Using computer simulations, we examine domain growth kinetics in the two-dimensional model. For long times after a quench from disorder, we find that the average domain sizeR(t) t ^1/3, in agreement with the prediction of Lifshitz-Slyozov-Wagner theory. Using a variety of methods, we analyze the critical properties of the associated second-order transition. Our analysis indicates that this model does not fall within either the Ising or mean-field classes.     

Universality of the Kondo effect in quantum dots with ferromagnetic leads

We investigate quantum dots in clean single-wall carbon nanotubes with ferromagnetic PdNi-leads in the Kondo regime. Most of the Kondo resonances exhibit a splitting, which depends on the tunnel coupling to the leads and an external magnetic field B, but only weakly on the gate voltage. Using numerical renormalization group calculations, we demonstrate that all salient features of the data can be understood using a simple model for the magnetic properties of the leads. The magnetoconductance at zero bias and low temperature depends in a universal way on gμ(B)(B-B(c))/k(B)T(K), where T(K) is the Kondo temperature and B(c) the external field compensating the splitting.     

Spin-dependent phase diagram of the nuT=1 bilayer electron system

We show that the spin degree of freedom plays a decisive role in the phase diagram of the nu(T)=1 bilayer electron system using an in-plane field B( parallel) in the regime of negligible tunneling. We observe that the phase boundary separating the quantum Hall and compressible states at d/l(B) = 1.90 for B(parallel) = 0 (d: interlayer distance, l(B): magnetic length) steadily shifts with B(parallel) before saturating at d/l(B) = 2.33 when the compressible state becomes fully polarized. Using a simple model for the energies of the competing phases, we can quantitatively describe our results. A new phase diagram as a function of d/l(B) and the Zeeman energy is established and its implications as to the nature of the phase transition are discussed.     

有机PIN型太阳能电池的数值模拟

从有机太阳能电池的工作机理出发,给出了有机P-I-N型有机太阳电池的理论模型,并对模型的激子产生率和载流子浓度分布进行了数值模拟,分析了光强和载流子迁移率对电池效率的影响,为高效率的此类电池的设计提供了理论依据。     

Weak radiative decays of baryons

Using recent experimental baryon weak radiative decay data for the fiveB→B′γ decays, we employ the pole model self-consistently to extract the reduced matrix elements 〈B′|H _w|B〉. The resulting pattern is compatible with weak pion decaysB→B′π and also with the quark model.     

Cluster Separability in Relativistic Quantum Mechanics

Using a simple model we provide a quantitative study of the size of the corrections needed to restore cluster properties to the construction of Poincaré invariant dynamical models with kinematic spins, first provided by B. Bakamjian and L. H. Thomas. Our model calculations suggest that these corrections are too small to have a quantitative impact on nuclear physics observables calculated using models with meson and nucleon degrees of freedom.     

Interplay of noncoding RNAs,mRNAs, and proteins during the growth of eukaryotic cells

Numerous biological functions of noncoding RNAs (ncRNAs) in eukaryotic cells are based primarily on their ability to pair with target mRNAs and then either to prevent translation or to result in rapid degradation of the mRNA-ncRNA complex. Using a general model describing this scenario, we show that ncRNAs may help to maintain constant mRNA and protein concentrations during the growth of cells. The possibility of observation of this effect on the global scale is briefly discussed.     

Spectral variations in the optical transition matrix element and their impact on the optical properties associated with hydrogenated amorphous silicon

Using an empirical model for the density of states functions associated with hydrogenated amorphous silicon, in conjunction with an elementary model for the optical transition matrix elements, we aim to explore how variations in the matrix elements impact upon the spectral dependence of the optical properties associated with this material. We also wish to ascertain as to whether or not the hydrogenated amorphous silicon mobility gap result suggested by Jackson et al. [W.B. Jackson, S.M. Kelso, C.C. Tsai, J.W. Allen, S.-J. Oh, Phys. Rev. B 31 (1985) 5187] is consistent with the results of the experiment. We find that the mobility gap value suggested by Jackson et al. is too large. An upper bound on the mobility gap associated with hydrogenated amorphous silicon of 1.68 eV is suggested instead. Electrical measurements performed on undoped hydrogenated amorphous silicon yield a mobility gap value that is consistent with this bound.     

Improved Measurement of the Cabibbo-Kobayashi-Maskawa angle alpha using B0(B) --> rho+rho- decays

We present results from an analysis of B(0)B(0)--> rho(+)rho(-) using 232 x 10(6) Gamma (4S) --> BB decays collected with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. We measure the longitudinal polarization fraction f(L) = 0.978 +/- 0.014(stat) + 0.021 / -0.029(syst) and the CP-violating parameters S(L)= -0.33 +/- 0.24(stat) + 0.08 / -0.14(syst) and C(L)= -0.03 +/- 0.18(stat) +/- 0.09(syst). Using an isospin analysis of B --> rhorho decays, we determine the unitarity triangle parameter alpha. The solution compatible with the standard model is alpha = (100 +/- 13) degrees.     

IBM-2 calculations of some even-even selenium nuclei

In this study, we determined the most appropriate Hamiltonian that is needed for present calculations of nuclei in the A≅ 80 region by the view of interacting boson model (IBM-2). Using the best-fitted values of parameters in the Hamiltonian, we have calculated energy levels and B(E2) values for a number of transitions in some doubly even Se nuclei. The results were compared with the previous experimental and theoretical data and it is observed that they are in good agreement. The calculations have been extended to Se isotopes with A < 76 for which some B(E2) values are still not known.     

Reorientational optical nonlinearity of nematic liquid-crystal cells near the nematic-isotropic phase transition temperature

We address the reorientational optical nonlinearity of homogeneously aligned neamtic liquid-crystal (NLC) cells. The propagation of light in NLC cells depend strongly on temperature. At a temperature approaching the clearing point, an undulating beam and multifocal points are observed in the NLC cell by use of a polarizing optical microscope. Using a conoscopic technique, we observed novel consecutive concentric and parabolic patterns projected onto a screen. Optical energy is considered to compete with thermal energy to affect NLC's orientation and to generate singularities in the steady state. A model of the configuration of the liquid crystal's orientation is proposed.     

Order-disorder transitions: structural and magnetic ordering in double perovskites

Using an effective lattice gas-like model for B-B′ site ordering we study order-disorder transitions in double perovskite materials A₂BB′O₆. We motivate this effective model from a microscopic hamiltonian. Using this model, we are able to address several experimentally observed issues including nonmonotonic dependence of the degree of order on annealing temperature, and the rapid decrease of order upon overdoping with either B or B′ species. We also study ordering in the ‘ternary’ compounds A₂BB′_1−yB″_yO₆, using a variant of the Blume-Emery-Griffiths model. Several issues related to structural and magnetic ordering are discussed.     

Contribution to the study of structural and elastic properties of wüstite under pressure up to 140 GPa by pseudopotential calculations

Using first-principles calculations based on the density functional theory and the generalized gradient approximations, we have studied the effect of high pressures up to 140 GPa on the structural and elastic properties of wüstite. Our results indicate that FeO undergoes a structural phase transition from NaCl-type (B1) to NiAs-type (B8) almost at the pressure of 77 GPa. The density increases across this transition by about 5%, which is a higher value than that obtained in other researches. We can clearly present the wüstite elastic properties and isotropic wave velocities which are not already studied in this range of pressure, and we could compare these results with the available experiment data, especially with that of PREM model.     

Zipf's law in gene expression

Using data from gene expression databases on various organisms and tissues, including yeast, nematodes, human normal and cancer tissues, and embryonic stem cells, we found that the abundances of expressed genes exhibit a power-law distribution with an exponent close to -1; i.e., they obey Zipf's law. Furthermore, by simulations of a simple model with an intracellular reaction network, we found that Zipf's law of chemical abundance is a universal feature of cells where such a network optimizes the efficiency and faithfulness of self-reproduction. These findings provide novel insights into the nature of the organization of reaction dynamics in living cells.     

Search for B0 decays to invisible final states and to nunugamma

We establish upper limits on branching fractions for B0 decays to final states where the decay products are purely invisible (i.e., no observable final state particles) and for B0 decays to nunugamma. Within the standard model, these decays have branching fractions that are below current experimental sensitivity, but various models of physics beyond the standard model predict significant contributions from these channels. Using 88.5 x 10(6) BB pairs collected at the Upsilon(4S) resonance by the BABAR experiment at the PEP-II e(+)e- storage ring at the Stanford Linear Accelerator Center, we establish upper limits at the 90% confidence level of 22 x 10(-5) for the branching fraction of B0-->invisible and 4.7 x 10(-5) for the branching fraction of B0-->nunugamma.     

Understanding ultrahigh doping: the case of boron in silicon

Using first-principles calculations, we develop a theory for ultrahigh impurity doping in semiconductors. Our study of B in Si explains why boron solubility in epitaxial growth could exceed the solid solubility to reach the kinetic solubility, and, with adequate surface passivation, to reach even higher values. We further show that the partial ionization at high B concentration, C(B), observed by experiment is predominantly an electron chemical potential effect, not a boron clustering effect. Our calculated hole concentration over a wide C(B) range is in reasonable agreement with experiments.