Adhesion comparison of human bone marrow stem cells on a gradient wettable surface prepared by corona treatment

Corona discharge treatment was applied to modify the surface of polyethylene (PE). The wettability of PE surface was gradually increased by power increase of a corona treatment along the PE length, indicating that the hydrophilicity of PE surface increased gradually. The adhesion and proliferation behavior of human bone marrow stem cells (hBMSCs) on the gradient PE surface was evaluated. We found that hBMSCs were adhered to and proliferated on better highly hydrophilic than hydrophobic surfaces. The plot of proliferation rate vs. the water contact angles was parabolic. These results indicate that surface wettability plays an important role in the cell attachment and proliferation.     

ⅡA,ⅡB族第一激发态原子中的角动量耦合

随着主子量子数ｎ增大，ⅡＡ，ⅡＢ族第一激发态原子中价壳电子间库仑排斥作用减弱，电子自身自旋－轨道相互作用相对增强，从而导致其对ＬＳ耦合方式的逐渐偏离和ｉｊ耦合方式的逐渐介入，组态混合方法可用来定量计算ＬＳ耦合方式的偏离程度。     

Possible stretched exponential parametrization for humidity absorption in polymers

Polymer thin films have irregular transient current characteristics under constant voltage. In hydrophilic and hydrophobic polymers, the irregularity is also known to depend on the humidity absorbed by the polymer sample. Different stretched exponential models are studied and it is shown that the absorption of humidity as a function of time can be adequately modelled by a class of these stretched exponential absorption models.     

Particle Creation in Cosmological Models with Varying Gravitational and Cosmological “Constants”

Einstein's field equations with variablegravitational coupling G = G(t) and decaying vacuumenergy density jj63v64145m388g4/xxlarge923.gif" alt="Lambda" align="BASELINE" BORDER="0"> = jj63v64145m388g4/xxlarge923.gif" alt="Lambda" align="BASELINE" BORDER="0">(t) are considered asdescribing matter creation in a cosmological framework.The particle creation rate is determined by thevariation rate of both G and jj63v64145m388g4/xxlarge923.gif" alt="Lambda" align="BASELINE" BORDER="0">. By consideringsimple phenomenological evolution laws for G and Lambda,an exact solution of the gravitational field equationsfor a flat Friedmann-Robertson-Walker (FRW)space-time is obtained leading to a self-consistentcosmological model describing matter and entropygeneration in the very early Universe.     

Functionalization and bioactivity in vitro of mesoporous bioactive glasses

Amino and carboxylic groups functionalized mesoporous bioactive glasses (denoted as N-MBGs and C-MBGs, respectively) were successfully synthesized through a post-grafting process and characterized by XRD, N₂ sorption, TEM, FT-IR and TG techniques. Their in vitro bioactivity and degradation behavior were investigated in simulated body fluid and examined by various techniques. The results demonstrate that the bioactivity of all the samples and the morphology of carbonated hydroxyapatite were affected remarkably by the introduction of functional groups. Spherical carbonated hydroxyapatite particles were observed grown on the N-MBGs surfaces after soaking in simulated body fluid for 8 h, which is different from the rod-like carbonated hydroxyapatite grown on conventional mesoporous bioactive glasses. While for C-MBGs, the nucleation and growth rate of carbonated hydroxyapatite was decreased at increased contents of carboxylic groups.     

Self-assembly of silanated poly(ethylene glycol) on silicon and glass surfaces for improved haemocompatibility

Surface immobilization of poly(ethylene glycol) (PEG) is an effective method to produce a material surface with protein repulsive property. This property could be made permanent by using covalent grafting of the PEG molecules onto material surfaces. In this study, self-assembled monolayers (SAMs) of PEG on silicon-containing materials (silicon chip and glassplate) were obtained through a one-step coating procedure of one kind of silanated PEG molecules made through the reaction between monomethoxy PEG and 3-isocyanatopropyltriethoxysilane. Atomic force microscopy (AFM) and water static contact angle measurement were employed to investigate the surface topography and wettability of the PEGylated material surfaces. The changes in the topography and the water contact angle of the surfaces with time of incubation in PBS solution were also measured. The results revealed that stable and uniform self-assembled monolayers of PEG could be formed on silicon or glass surfaces by simply soaking the substrates in the solution of silanated PEGs. The covalent coupling of PEGs to the substrates was also confirmed. In order to evaluate the stability of the SAMs, blood compatibility of the modified glassplate surface was evaluated by measuring full blood activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT), as well as by scanning electron microscopy (SEM) analysis of the appearance of adherence and denaturation of blood platelets onto the glassplate. The silanated PEGs were shown to have good effect on the protein-repulsion as well as haemocompatibility of the substrates.     

Polarizations on Abelian Varieties and Self-dual ℓ-adic Representations of Inertia Groups

It is well known that every finite subgroup of GL _d (Q _{jj386r0v264l/xxlarge8467.gif" alt="ell" align="BASELINE" BORDER="0">}) is conjugate to a subgroup of GL _d (Z _{jj386r0v264l/xxlarge8467.gif" alt="ell" align="BASELINE" BORDER="0">}). However, this does not remain true if we replace general linear groups by symplectic groups. We say that G is a group of inertia type of G is a finite group which has a normal Sylow-p-subgroup with cyclic quotient. We show that if jj386r0v264l/xxlarge8467.gif" alt="ell" align="BASELINE" BORDER="0">>d+1, and G is a subgroup of Sp _2d (Q _{jj386r0v264l/xxlarge8467.gif" alt="ell" align="BASELINE" BORDER="0">}) of inertia type, then G is conjugate in GL _2d (Q _{jj386r0v264l/xxlarge8467.gif" alt="ell" align="BASELINE" BORDER="0">}) to a subgroup of Sp _2d (Z _{jj386r0v264l/xxlarge8467.gif" alt="ell" align="BASELINE" BORDER="0">}). We give examples which show that the bound is sharp. We apply these results to construct, for every odd prime jj386r0v264l/xxlarge8467.gif" alt="ell" align="BASELINE" BORDER="0">, isogeny classes of Abelian varieties all of whose polarizations have degree divisible by jj386r0v264l/xxlarge8467.gif" alt="ell" align="BASELINE" BORDER="0">². We prove similar results for Euler characteristic of invertible sheaves on Abelian varieties over fields of positive characteristic.     

Staged Development of Modified Silicon Dioxide Films

The hydrolytic generation of SiO₂ films from chlorosilanes or alkoxysilanes is interrupted by incorporating labile organic groups which stop SiO₂ formation at a processable prepolymer stage. The monomers for the prepolymer have electron withdrawing substituents in the jj25320223n37722/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0"> -position. The organic groups are removed from the prepolymer at low temperature, extruding ethylene. The formation of SiO₂ proceeds by intramolecular condensation of the electronegative substituents which are now in a hydrolytically unstable bond with silicon and hydroxyl groups or ambient moisture. Films of the prepolymer spun onto silicon wafers are converted into uniform SiO₂-rich films at temperatures between 150–400°C.     

Tunable Photoluminescence Spectra of Doped Semiconductor Superlattices

Taking into account the density state tails appearing due to fluctuations of impurity concentrations, the spontaneous emission spectra of doped semiconductor superlattices are calculated. In the framework of the model developed, the explanation of the experimentally observed longwave edge and the shift of the photoluminescence spectra with increase in the excitation level and temperature is given. The role of the defects formed on jj5m82262v25w/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-irradiation is discussed, and the lifetime of current carriers is evaluated depending on the design parameters and excitation conditions of the GaAs doped superlattices.     

Molecular dynamics simulations of the interaction between 60° dislocation and self-interstitial cluster in silicon

Molecular dynamics simulations are performed to investigate the interaction between 60° shuffle dislocation and tetrainterstitial (I₄) cluster in silicon, using Stillinger-Weber (SW) potential to calculate the interatomic forces. Based on Parrinello-Rahman method, shear stress is exerted on the model to move the dislocation. Simulation results show that the I₄ cluster can bend the dislocation line and delay the dislocation movement. During the course of intersection the dislocation line sections relatively far away from the I₄ cluster accelerate first, and then decelerate. The critical shear stress unpinning the 60° dislocation from the I₄ cluster decreases as the temperature increases in the models.