The kernel of DWBA transition amplitude in atom–diatom reactive scattering

The kernel of the distorted-wave Born approximation (DWBA ) transition amplitude will be explored with attention to the atom–diatomic molecule reactive scattering process of A + BC → AB + C. Our study of the kernel reveals valuable intrinsic properties regarding the state-to-state reactive scattering process. In particular, such a study will help us to better understand (i) the favored geometric configuration during collision, (ii) the spatial domain of contribution to the differential and total cross sections, and (iii) the structural dependence of the kernel distribution on the mass ratio of the reactant molecule BC and the departing atom C, particularly in the case of colinear rearrangement collisions. In this study we choose the FH₂ system as an illustration.     

Study of the electronic energy band structure of polyethylene using MINDO/3

The electronic structure of polyethylene has been calculated using crystal orbital theory and the latest version (MINDO/3) of the MINDO semi-empirical SCF MO method. The results are in better agreement with the observed photoelectron spectrum than those given by an analogous calculation using MINDO/2, which in turn has been shown superior to treatments based on EHT, CNDO, INDO, or ab initio SCF procedures.     

Total dynamic structure factor of icosahedral and As-quenched and relaxed glassy Pd58.8Si20.6U20.6 measured at 296 K

The total dynamic structure factorsS(Q, ) of icosahedral, glassy Pd_58.8Si_20.6U_20.6, and the crystallized sample have been determined at room temperature using inelastic scattering of cold neutrons (IN6 of ILL). In contrast to the static structure factorS(Q), where the long range bond orientational order (BOO) leads to pronounced diffraction peaks with finite half width, the dynamic structure factor shows little or no influence of the long range BOO on the atomic dynamics of icosahedral PdSiU in the range of frequencies (0.525 meV) and momentum transfers Q(5Q30 nm^–1 for inelastic scattering) investigated here. The wavelength-dependence of the atomic dynamics of icosahedral PdSiU is very similar to that of the metallic glass and is different from that of the crystallized sample. As for glassy PdSiU no well defined vibrational collective excitations are found as peaks in the inelastic part ofS(Q, ) of the icosahedral sample,-quite in contrast to theoretical expectations and to the dispersions of pronounced excitations determined under identical experimental conditions fromS(Q, ) of the crystallized sample. On structural relaxation of the metallic glass Pd_58.8Si_20.6U_20.6 the largest amount of low energy modes is annealed out at lowest energy.Dedicated to Professor Harry Thomas on the occasion of his 60th birthday     

Self-assembling semicrystalline polymer into highly ordered, microscopic concentric rings by evaporation

A drop of semicrystalline polymer, poly(ethylene oxide) (PEO), solution was placed in a restricted geometry consisting of a sphere on a flat substrate (i.e., sphere-on-flat geometry). Upon solvent evaporation from the sphere-on-flat geometry, microscopic concentric rings of PEO with appropriate high molecular weight were produced via controlled, repetitive pinning ("stick") and depinning ("slip") cycles of the contact line. The evaporation-induced concentric rings of PEO exhibited a fibrillar-like surface morphology. Subsequent isothermal crystallization of rings at 40 and 58 degrees C led to the formation of multilayer of flat-on lamellae (i.e., spiral morphology). In between adjacent spirals, depletion zones were developed during crystallization, as revealed by AFM measurements. The present highly ordered, concentric PEO rings may serve as a platform to study cell adhesion and motility, neuron guidance, cell mechanotransduction, and other biological processes.     

Self-assembly of gradient concentric rings via solvent evaporation from a capillary bridge

A drop of solution containing nonvolatile solute is allowed to evaporate from a sphere-on-flat geometry. Left behind is a striking pattern of gradient concentric rings with unprecedented regularity. The center-to-center distance between adjacent rings, lambda(C-C), and the height of the ring, h(d), are strongly affected by the concentration of the solution and the properties of the solvent. The nature of the formation of regular gradient ring patterns during the course of irreversible solvent evaporation is revealed through theoretical calculations based on the mass conservation of the solution.     

A Biodegradable Polymersome Containing Bcl‐xL siRNA and Doxorubicin as a Dual Delivery Vehicle for a Synergistic Anticancer Effect

Combined cancer treatment via co‐delivery of siRNAs and an anticancer drug can be a promising strategy due to the synergistic effect of simultaneously minimizing gene/drug administration. In this study, Bcl‐xL siRNA and doxorubicin (DOX) are encapsulated into designed methoxy‐poly(ethylene glycol)‐block‐poly(D ,L ‐lactic acid) (mPEG‐b‐PLA) block copolymer polymersomes (PSomes). A study of the cytotoxicity of Bcl‐xL siRNA and DOX co‐encapsulated PSomes (CPSomes) shows more inhibited proliferation of MKN‐45 and MKN‐28 human gastric cancer cell lines than only gene‐ and drug‐loaded ones. Consequently, these results demonstrate that co‐delivery of genes and drugs using PSomes results in a synergistic efficacy and indicates the potential of PSomes as efficient nanocarriers for combined cancer therapy.

     

Adsorption and separation of proteins by a synthetic hydrotalcite

In this study, the potential use of a synthetic Mg/Al hydrotalcite (layered double hydroxide) as a novel chromatography material for protein purification was investigated. The hydrotalcite is present in its carbonate form and is characterized by an Al/Mg-ratio of 1.85. Zetapotential measurements confirm a positive surface potential up to pH 10 suggesting applicability as anion exchanger. The binding of model proteins covering a broad range of isoelectric points and molecular weights was performed at different pH-values under batch conditions to evaluate the binding behaviour of the hydrotalcite. Furthermore, static binding capacities were exemplarily determined for hemoglobin and human serum albumin. Additionally, the adsorption and elution of hemoglobin was studied under dynamic conditions. The binding behaviour of the hydrotalcite was compared to commercially available anion exchangers and was found to be a function of pH, depending on the model protein. Variant adsorption behaviour is explained by further interactions like hydrogen bonds and by an unequal charge distribution over the protein surfaces. The hydrotalcite reveals high adsorption capacities under static (260 mg/g) as well as under dynamic conditions (88 mg/g at 34 cm/h; 61 mg/g at 340 cm/h). With appropriate buffers like 500 mM carbonate (pH 10) the adsorbed proteins can be nearly completely desorbed making regeneration possible. Due to the binding and elution properties it is concluded, that the hydrotalcite can serve anion exchange material for chromatographic protein separations.