Vibrational energy transfer in H2 + He

A semiclassical approach is developed to study vibrational energy transfer in H₂ + He by use of the a priori interaction potential including all nonzero impact parameter collisions. The calculated values of the rate coefficient are found to be in excellent agreement with experimental data which are available in the temperature ranges 60–450 K and 1350-3000 K. The temperature dependence is shown to seriously deviate from the Landau-Teller prediction below 1000 K. The calculation was carried out over the temperature range of 30 to 10000 K.     

Surface-initiated growth of poly d(A-T) by Taq DNA polymerase

In this paper, we report surface-initiated d(A-T) polymerization by Taq DNA polymerase as a method for constructing DNA-tethered surfaces using an enzyme. The enzymatic polymerization was conducted successfully via two steps: tethering of oligo d(A-T)s onto the surface presenting carboxylic acids by amide coupling and surface-initiated polymerization using Taq DNA polymerase. In this enzymatic polymerization process, the design and construction of carboxylic acid-presenting surfaces were found to be an important factor: DNA growth did not occur on the gold surface coated only with the self-assembled monolayer (SAM) of 16-mercaptohexadecanoic acid (MHDA), but effectively proceeded on the surfaces presenting mixed SAMs of MHDA and 1-pentadecanethiol. The coupling of oligo d(A-T)s and the subsequent DNA polymerization reaction were characterized by polarized infrared external reflectance spectroscopy, ellipsometry, X-ray photoelectron spectroscopy, and atomic force microscopy.     

N-isobutyloxycarbonylation for improved detection of 3'-hydroxystanozolol and its 17-epimer in doping control

An improved screening method was developed for 3'-hydroxystanozolol and its 17-epimer in human urine involving gas chromatography-mass spectrometry (GC-MS) with N-isobutyloxycarbonyl (isoBOC) and O-trimethylsilyl (TMS) derivatization. A procedure was reported previously for the pentane extraction of many steroids from urine in doping control, but it was not suitable for the detection of stanozolol metabolites. Compared with the n-pentane extraction method, which gave a poor recovery (< 10%), isoBOC extraction resulted in a good recovery (> 80%). The sensitivity and specificity of mixed N-isoBOC-O-TMS derivatization were adequate for the detection of 3'-hydroxystanozolol and its 17-epimer when 3 ml of urine was used with spiking at a level of 2 ng ml-1. When applied to a stanozolol-positive urine sample, the proposed method allowed rapid and sensitive screening for the detection of 3'-hydroxystanozolol and its 17-epimer.     

Thermal properties of bio flour-filled polypropylene bio-composites with different pozzolan contents

In this study, the thermal properties of bio-flour-filled, polypropylene (PP) bio-composites with different pozzolan contents were investigated. With increasing pozzolan content, the thermal stability, 5% mass loss temperature and derivative thermogravimetric curve (DTG_max) temperatures of the bio-composites slightly increased. The coefficient of thermal expansion (CTE) and thermal expansion of the bio-composites decreased as the pozzolan content increased. The glass transition temperature (T _g), melting temperature (T _m) and percentage of crystallinity (X _c) of the bio-composites were not significantly changed. The thermal stability, thermal expansion and X _c of the maleic anhydride-grafted PP (MAPP)-treated bio-composites were much higher than those of non-treated bio-composites at 1% pozzolan content due to enhanced interfacial adhesion. X-ray diffraction (XRD) analysis confirmed the crystallinity of pozzolan-added bio-composites. From these results, we concluded that the addition of pozzolan in the bio-composites was an effective method for enhancing the thermal stability and thermal expansion.     

Alcohol sensing membrane based on immobilized ruthenium(II) complex in carboxylated PVC and surface covalently bonded alcohol oxidase

Alcohol sensing membranes coated on overhead transparency films for the continuous monitoring of ethanol, propanol and butanol are presented. Alcohol oxidation catalyzed by alcohol oxidase in conjunction with the fluorescence quenching reaction of oxygen-sensitive dye ion-pair, tris(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) didodecylsulphate was chosen for the determination. Alcohol oxidase was immobilized covalently on a plasticized carboxylated poly(vinyl chloride) membrane and the oxygen-sensitive dye ion-pair was entrapped in the same membrane. The sensing membrane relates oxygen consumption, as a result of enzymatic oxidation, to alcohol concentration. Measurements have been performed in air-saturated alcohol standard solutions of pH 7.0. Storage stability, reproducibility and the effect of pH on sensing membrane performance have been studied in detail. The alcohol sensing membrane proposed here is simple to prepare and has a fairly rapid response time of <1 min. It has been successfully applied to the determination of the ethanol contents in various spirits.     

Determination of copper(II) in various samples by flame atomic absorption spectrophotometry after column preconcentration onto pulverized Amberlite XAD-4 loaded with N-benzoylphenylhydroxylamine

A sensitive technique for the determination of trace Cu(II) in various samples after column preconcentration by adsorbing onto pulverized Amberlite XAD-4 loaded with N-benzoylphenylhydroxylamine (BPHA) was developed. Several experimental conditions, such as the size of XAD-4, adsorption flow rate, pH of sample solution, and so forth, were optimized. The interfering effects of diverse concomitant ions were investigated. Al(III), Fe(III), Ni(II), and Co(II) interfered, but the interference by these ions was completely eliminated by adjusting the amount of XAD-4-BPHA resin to 0.30 g. The dynamic range, the correlation coefficient (R₂), and the detection limit obtained by the proposed technique were 1.0–60, 0.9953, and 0.83 ng/mL, respectively. For validating the technique, the aqueous samples (stream water, reservoir water, and wastewater), the diluted brass sample, and the plastic sample were used as real samples. Recovery yields of 94–102% were obtained. These measured data were not different from ICP-MS data at the 95% confidence level. This method was also validated by rice flour CRM (normal, fortified) samples. Based on the results of the experiment, it has been found that the proposed technique can be applied to the determination of Cu(II) in various real samples. The text was submitted by the authors in English.     

Tuning chirality of single-wall carbon nanotubes by selective etching with carbon dioxide

CO2 molecule chemisorbs selectively on the zigzag tube edge without an activation barrier, whereas it physisorbs on the armchair edge of nanotubes. In addition, carbon nanotubes can be etched by an adsorbed oxygen atom of CO2 molecule. From our results, we suggest a selective etching mechanism for tuning the chirality of the mass-produced carbon nanotubes.     

On an elaboration of M. Kac's theorem concerning eigenvalues of the Laplacian in a region with randomly distributed small obstacles

We removem-balls of centersw ₁,...,w _m with the same radius α/m from a bounded domain Ω inR ³ with smooth boundary γ. Let μ _k (α/m;w(m)) denote thek-th eigenvalue of the Laplacian in Ω/m-balls under the Dirichlet condition. We consider μ _k (α/m;w(m)) as a random variable on a probability space (w ₁,...,w _m)∈Ω × ... × Ω and we examine a precise behaviour of μ _k (α/m;w(m)) asm → ∞. We give an elaboration of. M. Kac's theorem.