Electrochemical reduction of Eu3+ in aqueous ethylene glycol solutions

The electrochemical behavior of the system Eu³⁺/Eu²⁺ in aqueous ethylene glycol solutions was studied by current reversal chronopotentiometry at a mercury pool electrode in the temperature range 20.0-50.0°C, with 1 M NaClO₄ as supporting electrolyte.Kinetic parameters for the charge transfer reaction and activation energies for diffusion and viscosity are presented.     

On the max-entropy rule for a binary search tree

Summary A modified max-entropy rule is proposed for constructing nearly optimum binary search tree in the case of ordered keys with given probabilities. The average cost of the trees obtained by this rule is shown to be bounded by the entropy of the probability distribution plus a constant not larger than one. An algorithm for implementing this rule is then suggested and its complexity is investigated in a probabilistic setting.     

College student drinking and meaning in the pursuit of life goals.

The current study was designed to examine the association between risky alcohol use and life goals among college students. Introductory psychology students completed a questionnaire that included measures of typical life goals and alcohol use behavior. Students listed their 5 most typical life goals and rated them each on a series of dimensions from which 2 factors were derived (i.e., Goal Meaning, Goal Efficacy). Hierarchical regression analyses showed that the lower levels of goal meaning were associated with more heavy episodic use of alcohol and alcohol-related negative consequences. Results are consistent with motivational models of drinking that depict alcohol use as a function of satisfaction from other life goals. Findings support the importance of understanding college student drinking within the broader context of life goal appraisal. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ultrasound effect on structure and properties of Cu–0.5Cr under upsetting

ABSTRACT

We studied the effect of the regimes of ultrasonic action on the structural transformation during free upsetting with 50% reduction of the copper alloy Cu–0.5Cr. In the process of deformation, the samples were subjected to intermittent and continuous ultrasonic actions. It can be noted that the application of ultrasonic vibrations in the process of deformation leads in both cases to a reduction in yield strength. Under a continuous ultrasonic action with a power of 640?W, the most developed structure is formed, with a fraction of high-angle boundaries equal to 32.4%, with the lowest values of coherent scattering regions, density of dislocations and microdistortions, while the decline in yield strength of the material under deformation is 40?MPa.

This paper is part of a Thematic Issue on Copper and its Alloys.     

Highly connected molecular graphs are rigid in three dimensions

We show that every 7-vertex-connected molecular graph is generically rigid in three dimensions. This verifies a special case of a conjecture of Lovász and Yemini. For this family of graphs the bound is best possible.     

Impact of gate poly doping and oxide thickness on the N- and PBTI in MOSFETs

We study n- and pMOS devices with 3.2–30 nm thick SiON or SiO₂ gate dielectrics and n⁺⁺ or p⁺⁺ doped polysilicon gates to identify the type and energetic location of defects created through bias temperature stress. The results clearly indicate a dependence of the type of BTS induced defects on the stress polarity and the gate poly doping. If holes are provided from the p⁺⁺ poly gate and the gate dielectric is sufficiently thin, NBTI-type donor-like defects may occur even under positive bias stress conditions. For devices with sufficiently thick dielectrics or n⁺⁺ poly gated devices, holes are absent during PBTI stress and acceptor-like defects are created.     

Comparison of urinary excretion of radon from the human body before and after radon bath therapy

Theoretically, the human body absorbs radon through the lungs and the skin and excretes it through the lungs and the excretory organs during radon bath therapy. To check this theory, the radon concentrations in urine samples were compared before and after radon bath therapy. During the therapy, the geometric mean (GM) and the geometric standard deviation of the radon concentration in air and in the bath water were 979 Bq m(-3), 1.58 and 73.6 Bq dm(-3), 1.1, respectively. Since radon was detected in each urine sample (GM around 3.0 Bq dm(-3)), urinary excretion of radon was confirmed. The results of this study can neither reject nor confirm the hypothesis of radon absorption through the skin. A 15 times higher increment of inhaled radon level did not cause significant changes in radon of urine samples.     

Characterization of ethylene‐propylene copolymers with high‐temperature gradient adsorption liquid chromatography and CRYSTAF

Blends of linear polyethylene (PE) and isotactic polypropylene (iPP) with different average molar masses and a series of ethylene‐propylene (EP) copolymers with different chemical composition as well as blends of PE, Ipp, and EP copolymers were separated using a carbon‐column packing (Hypercarb®) and gradients of 1‐decanol or 2‐ethyl‐1‐hexanol → 1,2,4‐trichlorobenzene (TCB). The separation is based on full adsorption of linear PE on the carbon sorbent at temperature 160°C. However, iPP is not adsorbed and elutes in size exclusion mode. The random EP copolymers have been adsorbed in the column packing and separated according to their average chemical composition after application of the gradient starting with alcohol and ending with pure TCB. The elution volumes of the copolymers depended linearly on the average concentration of ethylene in the copolymers. The HPLC elution profiles were correlated with the CRYSTAF elution profiles. In contrast to CRYSTAF, fully amorphous polyolefin samples were separated with the high‐temperature adsorption liquid chromatography. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Highly functionalized polystyrene by direct metalation—carboxylation

Summary Polystyrene was directly metalated using 1:1 mixture of n-butyllithium (n-BuLi) and potassium-t-butoxide (t-BuOK) in cyclohexane/hexanes at ambient temperature. The metalated polymer on reaction with solid carbon dioxide followed by a metal-proton exchange gave a carboxylated polymer containing 6.38–6.57 mmol acid/g polymer which corresponds to the introduction of carboxyl groups on 94–97% of the repeat units of polystyrene.Based on ¹³C nMR spectra meta, para and ortho aromatic ring substitution was proposed. No detectable backbone carboxylation occurs. the distribution of carboxylated sites on the aromatic ring: 9% ortho, 58% meta and 33% para. Quantitative ¹³C NMR analyses indicates essentially quantitative functionalization.