Observation of neutron truncation rod scattering

We report measurements of neutron truncation rod scattering. This surface-induced neutron scattering has been observed at the (111) surface of a perfect Si single crystal by a high-resolution three-crystal scattering experiment. We describe the details of the experiment and discuss the experimental findings within a kinematic approach. Possible applications of this new neutron scattering method lie in the field of surface magnetism and the study of surfaces of light-element systems.     

Synthesis,Configuration, and Antimicrobial Properties of Novel Substituted and Cyclized ‘2′,3″‐Thiazachalcones’

Nine new thiazachalcone‐based drugs, compounds 1 – 9 , were prepared and fully characterized. The configurations of the photochemical‐dimerization products 7 – 9 were rationalized by semi‐empirical calculations. Both the experimental data and the theoretical calculations showed that the δ‐truxinic acid type dimer is the most stable isomer of all. All compounds were tested for their antibacterial and antifungal activities. The N‐alkylated congeners 4 – 6 showed strong antimicrobial activities against various bacteria and a yeast‐like fungus. The MIC and MBC values were as low as 0.1 μg/ml. All the compounds were active against the Gram‐positive bacterium Staphylococcus aureus.     

GC–MS analysis and anti–microbial activity of Prunella vulgaris L. extracts

In this study, the chemical composition of the methanol, hexane and ethyl acetate extracts of Prunella vulgaris L. were investigated by gas chromatography–mass spectrometry (GC–MS) method. 2-hydroxy-5-methylbenzaldehyde (15.70%), linolenic acid (45.50%) and icosane (16.24%) were found to be the most abundant in methanol, hexane and ethyl acetate extracts, respectively. Following the determination of chemical components of the Prunella vulgaris L. extracts, their anti–microbial activities against certain human pathogenic bacteria were tested and minimal inhibitory concentrations (MIC) were determined. While some extracts of Prunella vulgaris L. show anti–microbial activity well above the standards (penicillin and tetracycline), it was determined that in general all the extracts showed good anti–microbial activity against these pathogenic bacteria.     

Effect of ethyl acetate on carbohydrate components and crystalline structure of pulp produced in aqueous acetic acid pulping

The aim of this study was to investigate the changes in carbohydrate components and the crystalline structure in hemp bast fibers by adding ethyl acetate to acetic acid/water pulping processes. It was found that ethyl acetate added to acetic acid/water process had a positive effect on yield, viscosity and carbohydrate components in pulp. It was assumed that the delignification ratio increased by adding ethyl acetate to aqueous acetic acid pulping. Xylose content in hemp bast fibers was affected more negatively in the ethyl acetate/acetic acid/water process than in the acetic acid/water one. Crystallinity and crystallite size were higher in pulp sample obtained by the acetic acid/water process without ethyl acetate.     

Designing patterned substrates to regulate the movement of capsules in microchannels

Using computational modeling, we simulate the fluid-driven motion of microcapsules on patterned surfaces to establish guidelines for creating simple microfluidic devices for bioassays and multistage chemical reactions. The microcapsules, which consist of an elastic shell and an encapsulated fluid, model biological cells or polymeric particles. We focus on patterned substrates that encompass chemically adhesive and mechanically compliant domains. By probing the interactions between the microcapsules and these patterned surfaces, we determine the factors that control the movement of the capsules along the substrates. Using this information, we optimize the arrangement of the adhesive and compliant surface domains to create robust systems that effectively discriminate between various soft particles moving through the microchannels and "autonomously" direct certain species to specific locations. These findings could facilitate the fabrication of low-cost, portable microfluidic devices for sorting cells or performing fundamental chemical studies.     

Solution-deposited organic-inorganic hybrid multilayer gate dielectrics. Design, synthesis, microstructures, and electrical properties with thin-film transistors

We report here on the rational synthesis, processing, and dielectric properties of novel layer-by-layer organic/inorganic hybrid multilayer dielectric films enabled by polarizable π-electron phosphonic acid building blocks and ultrathin ZrO(2) layers. These new zirconia-based self-assembled nanodielectric (Zr-SAND) films (5-12 nm thick) are readily fabricated via solution processes under ambient atmosphere. Attractive Zr-SAND properties include amenability to accurate control of film thickness, large-area uniformity, well-defined nanostructure, exceptionally large electrical capacitance (up to 750 nF/cm(2)), excellent insulating properties (leakage current densities as low as 10(-7) A/cm(2)), and excellent thermal stability. Thin-film transistors (TFTs) fabricated with pentacene and PDIF-CN(2) as representative organic semiconductors and zinc-tin-oxide (Zn-Sn-O) as a representative inorganic semiconductor function well at low voltages (<±4.0 V). Furthermore, the TFT performance parameters of representative organic semiconductors deposited on Zr-SAND films, functionalized on the surface with various alkylphosphonic acid self-assembled monolayers, are investigated and shown to correlate closely with the alkylphosphonic acid chain dimensions.     

An EPR study on cytosine irradiated

In this study, paramagnetic centers over the cytosine were formed by photolysis then these centers were investigated using EPR method. EPR signals were not recorded from non‐irradiated the cytosine, but irradiated polycrystalline exhibited complex EPR spectra. For obtaining of cytosine polycrystalline, novel crystallization method was performed on powder cytosine. Effective crystallization conditions were achieved by adjustment of the concentration of the metal ions, chemical solutions, NaCl, KCl, glacial asetic acid, nitric oxide, percloric acid, glutamic acid, and pH of buffer. Cytosine (C₄H₅N₂O) polycrystalline obtained were irradiated with ⁶⁰Co – rays at room temperature for 24 and 72 h. At the sample irradiated for 72 h, the paramagnetic centers were determined between 120 and 450 K by X‐band EPR spectrometer. The spectra were found to be dependent slightly on temperature. Two cation radicals were determined in the structure and these were called Radicals I and II. The g and hyperfine constants were found to be a_H2a = 61 G, a_N2 = 9.39 G, a_N1 = 7.15 G, and g₁=2.0026 for the Radical I; a_H3 = 10.57 G, a_H1 = 3 G, a_N3 = 6.72 G, a_N1 = 5.36 G for, and g₂=2.0034 the Radical II. Copyright © 2010 John Wiley & Sons, Ltd.     

X-band EPR study on benzo[c]cinnoline single crystals

The benzo[c]cinnoline compound has been crystallized in ethanol solution. These crystals have been irradiated with ⁶⁰Coγ-rays at room temperature. The crystals have been investigated by an X-band electron spin resonance (ESR) spectrometer two days after irradiation. Very strong ESR peaks have been observed at the temperatures between 130 and 430 K. However, a line broadening has been observed at 130 K. Also analyses found that EPR specra are temperature-dependent and show anisotropic behaviour.     

Magnetoresistance of two-dimensional tight-binding electrons in a weak magnetic field

We study the Anderson model on a two-dimensional square lattice with an applied weak magnetic field B which causes the hopping matrix elements to have Peierls phase factors. The recursion method is applied and B dependent conductivity σ(B) is calculated from the Kubo formula for different system sizes N and degree of disorder W. For large W there is no appreciable change of σ(B) with B, but its system size dependence is first an increasing and then a decreasing behavior.