Modification of polycarbonate surface properties by nano-, micro-, and hierarchical micro–nanostructuring

Polycarbonate surfaces were patterned with nanopillars, microbumps, or nanopillars superimposed on microbumps. Patterning was achieved by applying nanoporous anodized aluminum oxide (AAO) membranes, microstructured aluminum foil, or anodic alumina on microstructured aluminum as mold inserts in injection molding. The effect of the different-sized structures on properties of the polycarbonate surface was investigated in contact angle measurements with water and oleic acid. The water contact angle increased from 82° on the smooth surface to 139° on the hierarchical micro–nanostructure. The transmittance of the polycarbonate increased with nanopatterning, while the reflection properties of the polycarbonate surface decreased. Reflection was lowest for the nanostructure with 53 nm pillar diameter and 77 nm interpillar distance. Values ranged from 0.6 to 1.1% over the whole wavelength range of visible light, which was 4–5% units lower than the corresponding values for the smooth polycarbonate.     

Lattice structures and spreading models

We consider problems concerning the partial order structure of the set of spreading models of Banach spaces. We construct examples of spaces showing that the possible structure of these sets include certain classes of finite semi-lattices and countable lattices and all finite lattices. Research of the second named author was partially supported by the National Science Foundation. The third named author had a visiting appointment at the University of South Carolina for the 2004–05 academic year during part of his research.     

Microcalorimetric study of the binding of methotrexate and its metabolites to thymidylate synthase

Direct microcalorimetric measurements allow determination of both the δH and association constant of biological complexes ifK _a value does not exceed 10⁶ M ^?1. For higherK _a values, δH can obviously be determined; this paper describes an original microcalorimetric method that permits determination of such high association constants. This method is based on the analysis of the competitive effect between two ligands having the same binding site in their receptor. As an example, the affinity constant for thymidylate synthase of a novel antifolate, CB 3717. was found to be 1.4 · 10⁷ M ^?1 using methotrexate polyglutamate MTX-G2 (K _a=2.3·10⁵ M ^?1) as competitor.     

New Energetic Copper(II) Complexes With Pyrazolyl Type Ligands

Nine Cu^II complexes ( I – IX ) containing the azide ion and bis‐2,6‐(pyrazol‐1‐yl)pyridine (pp), bis‐2,6‐(pyrazol‐1‐yl)pyridine (dmpp), and 2‐(pyrazol‐1‐yl)‐6‐(3,5‐dimethylpyrazol‐1‐yl)pyridine (mpp), which are derivatives of pyrazolylpyridine, were prepared in nonaqueous medium. These complexes were characterized by elemental analyses and IR spectroscopy. Crystals of one of these complexes [CumppClN₃ ( VII )] were prepared in suitable size, and a molecular structure of this complex was obtained with X‐ray diffraction method. Complexes were examined by thermogravimetry and differential scanning calorimetry methods. Thermal decomposition was observed in complexes including two azide groups similar to that seen in explosives. In the complexes containing one azide group, formation of the Cu^I complexes was observed after thermal decomposition of the azide group.     

Study of the Coordination Properties of 1,2-Bis(2,6-dimethphenylamino) Glyoxime and Determine the Stability Constant of Its Complexes with Ni(II), Cu(II) and Zn(II) Metal Ions in Solution

This study aims to investigate the nature and type of complexes formed in solution between 1,2-bis(2,6-dimethphenylamino) glyoxime (DPG) and the ions Ni²⁺, Cu²⁺ and Zn²⁺. Potentiometric titration was used to follow the formation of complexes.The complexes formed were studied through the determination of stability constants of these complexes in mixed ethanol–aqueous solution at 25±0.1?°C and ionic strength of 0.1 mol?dm^?3 NaCl. The basicity of the ligand was also assessed by the determination of the dissociation constants of the ligand. All of the constants were determined by computer refinement of pH–volume data using the SUPERQUAD program. The species distribution diagrams were also calculated.Comparison with other vic-dioximes was made to provide reliable support for the formation of the proposed complexes in solution.     

The effect of hydrostatic pressure on subband structure and optical transitions in modulation-doped quantum well

Within the framework of effective-mass approximation, we have calculated theoretically the effects of hydrostatic pressure and doping concentration on subband structure and optical transitions in modulation-doped GaAs/Al_xGa_1−xAs quantum well for different well widths. The electronic structure of modulation-doped quantum well under the hydrostatic pressure is determined by solving the Schrödinger and Poisson equations self-consistently. The results obtained show that intersubband transitions and the subband energy levels in the modulation-doped quantum well can be significantly modified and controlled by the well width, donor concentration and hydrostatic pressure.     

Wood surface functionalization by means of low-pressure air plasma

Low-pressure plasma treatments in an radio frequency (RF) discharge of air have been used on the surface of wood to stimulate polar function groups onto pine and beach surfaces to enhance the wettability and activation. The effects of plasma treatments on the morphology and wettability of surfaces were characterized by using static contact angle measurements, attenuated total reflection Fourier transform infrared spectroscopy and scanning electron microscopy. A clear increase in the surface energy of the wood surface due to air plasma treatment was observed. The surfaces became highly hydrophilic when woods were exposed for 5 s or longer to the plasma discharge. The wettability of wood surface can be improved when oxygen functionalities were generated, which can be achieved directly in O-containing plasma or via post plasma reaction. A small reduction in the surface energy of the treated wood after 12 days of aging showed that the plasma-induced cross-linking in the surface of the wood was not the dominant phenomenon.     

Atmospheric pressure chemical vapour synthesis of silicon–carbon nanoceramics from hexamethyldisilane in high temperature aerosol reactor

Silicon–carbon nanoceramics have been synthesised from hexamethyldisilane (HMDS) by the atmospheric pressure chemical vapour synthesis (APCVS). Direct aerosol phase synthesis enables continuous production of high purity materials in one-stage process. The particle formation is based on the decomposition of the precursor in a high temperature reactor. Reaction of the gas phase species leads to homogeneous nucleation and formation of the nanoparticles with a narrow size distribution (geometric mean diameter range of particle number size distribution 160–200 nm with 1.5–1.6 geometric standard deviation at reaction temperatures 800–1200 °C). A systematic investigation of the influence of the process temperature on the powder characteristics, including the particle size, crystallinity, chemical structure, surface and bulk composition and surface morphology, was carried out. At the reactor temperature of 800 °C, the synthesised nanoparticles were amorphous preceramics containing mostly SiC₄, Si–CH₂–Si and Si–H units. The composition of the powder turned towards nanocrystalline 3C–SiC (crystal size under 2 nm) when the reaction temperature was increased to 1200 °C. The reaction temperature appeared to be a key parameter controlling the structure and properties of the synthesised powders.     

A three-component,one-pot synthesis of 1,8-naphthyridine and isoxazole derivatives and computational elucidation of the mechanism

Research on Chemical Intermediates - An efficient and general method for the synthesis of substituted 3,4-dimethylisoxazolo[5,4-b]pyridine-5-carboxamide and benzo[b][1,8]naphthyridine-3-carboxamide...