Fused thiophene-split oligothiophenes with high ionization potentials for OTFTs

Fused thiophene-split oligothiophenes were synthesized by Suzuki coupling. The relationship between the structure of these fused thiophene-split oligothiophenes and DH-6T (α,ω-dihexylsexithiophene) and their performance in OTFTs was discussed. The realignment of HTTfTTTH (2,5-bis-(5′-hexyl-[2,2′]bithiophenyl-5-yl)-thieno[3,2-b] thiophene) molecule on the substrate after annealing was revealed by X-ray diffraction and atomic force microscopy. A similar but novel compound, TTfTTT (2,5-bis-[2,2′]bithiophenyl-5-yl-thieno[3,2-b]thiophene), was also prepared and evaluated as an organic transistor material. Air stabilities of these three compounds in OTFT devices were affected mainly by chemical properties, but also by the ionization potentials (I_p) of these materials. Among the three compounds, HTTfTTTH had a higher I_p because the thiophene sequence was split by fused thiophene and the best air stability, due to the end-capping of its active α-positions by hexyl substitution.     

Non-isothermal kinetics of the thermal decomposition of gadolinium nitrate

High-level liquid waste (HLLW) contains more than 30 kinds of nitrates which consist of fission products. A series of such phenomena as evaporation, melting and thermal decomposition of HLLW takes place within the ‘cold cap’, which is floating on top of the molten glass pool. An understanding of the varied thermal decomposition behavior of various nitrates constituting HLLW is necessary to elucidate a series of phenomena occurring within the cold cap. In this study, gadolinium nitrate, which is one of main compositions of HLLW, was chosen as an example of the nitrate salt and its thermal decomposition was investigated using non-isothermal thermogravitmetry-differential thermal analysis-mass spectrometry and X-ray powder diffraction. Ozawa method was applied for gaining kinetic parameters for the consecutive reaction of gadolinium nitrate. Reaction rate equation of the decomposition under non-isothermal condition was described.     

Sedimentation behavior of mixed solid particles

During the material relocation phase of core-disruptive accidents in sodium-cooled fast reactors, the sedimentation behavior of fragmented debris discharged from the reactor core into the lower plenum region leading to a debris-bed formation is crucial in regard to in-vessel retention and safety concerns. The height of the beds formed may influence both the cooling of the bed from the decay heat in the fuel and the neutronic characteristics. To develop an experimental database of bed formation behavior, a series of experiments using simulant materials, namely, Al₂O₃, ZrO₂, and stainless steel, were performed under gravity-driven discharge of solid particles from a nozzle into a quiescent cylindrical water pool. The bed height was measured for particles of different size, density, and sphericity, and an injection nozzle with varying diameter, injection velocity, and injection height. From these experiments, an empirical correlation was established to predict the bed height for both homogeneous and mixed particles for the different properties. This correlation reproduces reasonably well the experimental trend in bed height with critical factors, which were identified in this and previous experiments.     

A Highly Active 4‐Siloxyproline Catalyst for Asymmetric Synthesis

trans‐4‐tert‐Butyldimethylsiloxy‐L ‐proline displays a greater catalytic activity than the parent proline without compromising the enantioselectivity, which widens the substrate scope in the α‐aminoxylation of carbonyl compounds, as well as O‐nitroso‐aldol/Michael, and Mannich reactions.     

On the approximation of protein threading

In this paper, we study the protein threading problem, which was proposed for predicting a folded 3D protein structure from an amino acid sequence. Since this problem was already proved to be NP-hard, we study polynomial time approximation algorithms. We show several hardness results for the approximation, which includes a MAX SNP-hardness result. We also show approximation algorithms for a special case and a general case, where a graph representing interactions between amino acid residues is restricted to be planar in a special case. For this special case, we obtain a constant approximation ratio.     

Rapid quantification of coliforms in ready-to-eat foods using lateral-flow immunochromatographic assay

The degree of coliform contamination in pastries was estimated based on culturing times until positive results were obtained with the lateral-flow immunochromatographic assay (LFIA). Coliform genera Citrobacter, Cronobacter, Enterobacter, Klebsiella, Kluyvera, Pantoea, Raoultella, and Serratia were detected in spoiled pastries, as established with next-generation sequencing. A lateral-flow test strip was constructed using antibodies recognizing the above genera. The culture times required for positive detection with LFIA were 0, 3, 6, and 9 hr at initial inoculation concentrations of 3.8, 2.8, 1.8, and 0.8 log₁₀ (cfu/ml), respectively. In pastries contaminated with >5.0, 3.0–5.0, 2.0–3.0 log₁₀ (cfu/g) coliform bacteria, samples became LFIA-positive from 3, 6, and 9 hr culture, respectively. LFIA showed negative for pastries with <2.0 log₁₀ (cfu/g) coliform contamination. The quantitative category of initial coliform content before culture was predictable with 87% accuracy. This novel method can be applied to monitor food safety of other ready-to-eat consumables.     

Ionic Conductivity of Cross-linked Polymethacrylate Derivatives/Cyclophosphazenes/Li<Superscript>+</Superscript> Salt Complexes

The role of cyclophosphazenes with oxyethylene chains (N₃P₃(OCH₂CH₂)_nOCH₃, (n = 3, 3, n = 7.2, 4) and N₄P₄[OC₆H₄O(CH₂CH₂O)_7.2CH₃]₈ (8) for the synthesis and ionic conductivity in polymethacrylate networks was studied. Reflecting the structural features of cyclophosphazenes, the ⁷Li NMR spectra of the mixture of 3 and LiN(SO₂CF₃)₂ showed that more than 40% of the Li⁺ salt could exist as a free ion at room temperature. Similar values were obtained for 4 and 8. Cross-linked methacrylate polymers (12–14, and 16–18) were prepared from the reaction of poly(ethylene glycol) methyl ether methacrylate and poly(ethylene glycol) dimethacrylate both in the presence of these cyclophosphazenes which act as molecular imprinting molecules (method II, M-II) and without the cyclophosphazene (method I) DSC studies of the imprinted polymer, 12(20)/3/Li⁺ system after removal of the cyclophosphazene showed that the glass transition temperature range (ΔT_g) becomes significantly narrower compared to that of the unimprinted 11(20)/3/Li⁺ system, where cross-linked polymer 11(20) was prepared in the absence of the cyclophosphazenes (method I, M-I). The ionic conductivity of the Li⁺/cross-linked polymer system was improved by the subsequent readdition of the cyclophosphazenes. The 12(20)/3/Li⁺ complex showed a conductivity of 1.1 × 10⁻³ S/cm at 90 °C, which was two times higher than that of the 11(20)/3/Li⁺ complex. The effectiveness of the small molecule imprinting technique for the preparation of cross-linked polyelectrolytes with high conductivity and mechanical stability is discussed. We dedicate this paper to Professor Christopher W. Allen for his creative, pioneering work in inorganic ring and inorganic-organic hybrid polymers.     

Dispersion control of immiscible polymer blend using selective heating by infrared laser irradiation

In this study, a selective heating technique by irradiating an infrared laser to an immiscible polymer blend was proposed to actively control the distribution of the dispersed phase in the blend. In the technique, the viscosity ratio between the matrix and dispersed phases was not changed by the molecular weight or shear rate but was changed by the controlled temperature distribution due to selective heating. The feasibility of the proposed technique was investigated through a numerical simulation of the temperature field and an experimental study using a test blend. The results showed that the technique successfully caused the deformation of relatively large droplets and enhanced the micro‐scale dispersion. It was also confirmed that the droplet size of the dispersed phase could be estimated by a simple method similar to the conventional technique: the chart of capillary number change with respect to the viscosity ratio. From the obtained results, it was concluded that the technique proposed in this study is a promising candidate for the development of a new blend process. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013