Grain-oriented calcium hydroxyapatite ceramic and film prepared by magnetic alignment

Grain-oriented calcium hydroxyapatite (HA) ceramics are potential to enhance or select their bioactive properties. In the current work, highly a-axis oriented calcium HA bulk and thick film samples were prepared by a novel process combining magnetic alignment and polymerization techniques. The slurry containing 40 vol.% commercial HA powder, monomer, initiator and catalyst were poured into a rubber mold for bulk samples or drop-coated on Al₂O₃ substrate for films at first, and then moved them into a vertical 10 T magnetic field. The HA particles in the low viscosity slurry were aligned by magnetic force and then in situ locked via polymerization of the slurry. After sintering, the grain-oriented HA ceramic bulk and thick film samples with a-axis parallel to the magnetic field direction were obtained. Theoretically, the grain-orientation can be easily controlled by adjusting the magnetic field direction.     

Medicare's search for effective obesity treatments: Diets are not the answer.

The prevalence of obesity and its associated health problems have increased sharply in the past 2 decades. New revisions to Medicare policy will allow funding for obesity treatments of proven efficacy. The authors review studies of the long-term outcomes of calorie-restricting diets to assess whether dieting is an effective treatment for obesity. These studies show that one third to two thirds of dieters regain more weight than they lost on their diets, and these studies likely underestimate the extent to which dieting is counterproductive because of several methodological problems, all of which bias the studies toward showing successful weight loss maintenance. In addition, the studies do not provide consistent evidence that dieting results in significant health improvements, regardless of weight change. In sum, there is little support for the notion that diets lead to lasting weight loss or health benefits. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Subchannel analysis of supercritical light water-cooled fast reactor assembly

Subchannel analyses have been carried out for supercritical water-cooled fast reactor fuel assembly. Peak cladding surface temperature difference arising from subchannel heterogeneities have been calculated by using the improved subchannel analysis code STARS and was evaluated to be about 18.5 °C. Several suggestions have been also made for reducing the PCST difference arising from channel heterogeneity. Influences of local power peaking on deflection of cladding surface temperature are explained with pin power distribution taken from core depletion calculation in this paper. Maximum cladding surface temperature at nominal condition is evaluated to be 645.3 °C over the cycle. Statistical thermal design uncertainty associated with PCST calculation is evaluated by Monte-Carlo sampling technique combined with subchannel analysis code. Maximum statistical design uncertainty of PCST is calculated to be 31 °C and is in a good agreement with that from RTDP method. Influence of downward flow in seed region on system sensitivity is investigated by improved Monte-Carlo thermal design procedure. Limiting thermal condition of MCST is 681 °C (650 °C of nominal + 31 °C) within 95/95 limit for SWFR.     

Block FEM for Time-Dependent Shear-Lag Behavior in Two I-Girder Composite Bridges

This paper presents a time-dependent finite-element analysis of a two I-girder composite bridge with a concrete slab. The creep and shrinkage of the concrete slab are considered as sources of time-dependent behavior. This analysis, unlike others, includes the shear-lag effect of the concrete slab on the time-dependent behavior of two I-girder bridges. An example calculation is given for a two-span continuous composite bridge with a cracking region in the concrete deck near the interior support. It is shown that the shear-lag effect becomes significant at the edge of the cracking region and at the bridge ends.     

Polyacylated Anthocyanins in Bluish-Purple Petals of Chinese Bellflower,Platycodon grandiflorum

The bluish-purple petals of Chinese bellflower, Platycodon grandiflorum (kikyo in Japanese), contain platyconin (1) as the major anthocyanin. Platyconin (1) is a polyacylated anthocyanin with two caffeoyl residues at the 7-position, and its color is stable in a diluted, weakly acidic aqueous solutions. HPLC analysis of the fresh petal extract showed the presence of several minor pigments. Photo-diode array detection of minor pigments suggested that some of these were polyacylated anthocyanins. To establish the relationship between structure and stability of the acylated anthocyanins and to obtain information on their biosynthetic pathways, minor pigments were isolated from the petals, and their structures were determined by MS and NMR analyses. Four known (2–5) and three new anthocyanins (6–8) were identified, which contained a delphinidin chromophore, and four of these (5–8) were diacylated anthocyanins, in which the acyl-glucosyl-acyl-glucosyl chain was attached at the 7-O-position of the delphinidin chromophore. These diacylated anthocyanins exhibited a bluish-purple color at pH 6, which was stable for more than a week.     

Production of Monopolar Ions from Streamer Coronas Induced by Very Short Pulse Voltage

The initial and time-dependent concentration of ions in the streamer coronas produced by very short pulse voltages with a half-tail of 100-500 as are measured under the condition that a dc bias voltage is applied between the corona and plate electrodes. The waveform of the corona current of both positive and negative polarities indicates that, although the plasma formation is made in a very short time of about 10 ns, the ionic current flowing across the electrode gap has a very long duration time of 1-3 ms. This is due to the slow processes of ion recombination and migration. The theoretical model of the ion separation process for production of monopolar ionic current is presented and confirmed by the experimental results. The initial ion concentration in these streamer coronas amounts to (5-6) x 109 ion paires/cm3 for both negative and positive streamers.     

Improving mixing characteristics with a pitched tip in kneading elements in twin‐screw extrusion

In twin‐screw extrusion, the geometry of a mixing element mainly determines the basic flow pattern, which eventually affects the mixing ability as well as the dispersive ability of the mixing element. The effects of geometrical modification, with both forward and backward pitched tips, of a conventional forward kneading disks element (FKD) in the pitched‐tip kneading disks element on the flow pattern and mixing characteristics are discussed. Numerical simulations of fully filled, nonisothermal polymer melt flow in the melt‐mixing zone were performed, and the flow pattern structure and the tracer trajectories were investigated. The pitched tips largely affect the inter‐disk fluid transport, which is mainly responsible for mixing. These changes in the local flow pattern are analyzed by the distribution of the strain‐rate state. The distribution of the finite‐time Lyapunov exponent reveals a large inhomogeneity of the mixing in FKD is suppressed both by the forward and backward tips. By the forward tips on FKD, the mixing ability is relatively suppressed compared to FKD, whereas for the backward tips on FKD, the mixing ability is enhanced while maintaining the same level of dispersion efficiency as FKD. From these results, the pitched tips on the conventional KD turn out to be effective at reducing the inhomogeneity of the mixing and tuning the overall mixing performance. © 2017 American Institute of Chemical Engineers AIChE J, 64: 1424–1434, 2018     

Structural determination of stretched helix and contracted helix having yellow and red colors of poly(2-ethynylnaphthalene) prepared with a [Rh(norbornadiene)Cl]2-triethylamine catalyst

The Rh-catalyzed polymerization of 2-ethynylnaphthalene (2EN) using ethanol or toluene solvents afforded helical poly(2-ethynylnaphthalene)s (P2EN)s, i.e., yellow-colored P2EN(Y) and red-colored P2EN(R) in good yields, respectively. The diffuse reflective UV–vis (DRUV–vis) spectra of P2EN(Y) and P2EN(R) in the solid phase showed broad absorption peaks at 445 nm and 510 nm, respectively. These helical and its crystal structures were investigated using wide angle X-ray scattering (WAXS), resonance laser Raman, and molecular mechanics calculation using MMFF94 force field. Based on these analyses, we found that P2EN(Y) was composed of stretched cis-transoid helices and P2EN(R) was composed of contracted cis-cisoid helices in which form intramolecular π-stacking by ca. 3.4 Å in distance between neighboring naphthyl rings. Furthermore, the contracted helix was energetically more stable than the stretched helix. The P2EN(Y) changed to a red-colored polymer, P2EN(Y-R), by immersion in toluene. This P2EN(Y-R) completely coincides with the P2EN(R) in its crystal structure and DRUV–vis spectrum.     

Generation of polyacetylene sulfoxide radicals through spin migration from the main-chain to the sulfoxide moiety in the side chain of poly[p-(n-butylsulfoxide)phenylacetylene] prepared with a [Rh(norbornadiene)Cl]2 catalyst

A phenylacetylene bearing an n-butylsulfoxide group, i.e., p-(n-butylsulfoxide)phenylacetylene (1) was prepared in high yields using the [Rh(norbornadiene)Cl]₂-NEt₃ catalyst in the presence of various solvents under mild conditions. The resulting polymer, poly[p-(n-butylsulfoxide)phenylacetylene] (poly(1)), was characterized in detail by ¹H NMR, ESR, laser Raman, and diffuse reflective UV-vis methods. The data clearly showed that cis-to-trans isomerization of the polymer can be induced when pressure is imposed to the polymer at room temperature, rotationally breaking the cis CC bonds to generate the cis and trans radicals. Further, the spin density in the cis radical was migrated from the main-chain to the sulfoxide moiety as the side chain of the phenyl ring to magnetically interact with the first two methylene protons in the n-butyl group giving a triplet line ESR spectrum with an extremely large g value, g = 2.0081.     

100‐period, 1.23‐eV bandgap InGaAs/GaAsP quantum wells for high‐efficiency GaAs solar cells: toward current‐matched Ge‐based tandem cells

Major challenges for InGaAs/GaAsP multiple quantum well (MQW) solar cells include both the difficulty in designing suitable structures and, because of the strain‐balancing requirement, growing high‐quality crystals. The present paper proposes a comprehensive design principle for MQWs that overcomes the trade‐off between light absorption and carrier transport that is based, in particular, on a systematical investigation of GaAsP barrier effects on carrier dynamics that occur for various barrier widths and heights. The fundamental strategies related to structure optimization are as follows: (i) acknowledging that InGaAs wells should be thinner and deeper for a given bandgap to achieve both a higher absorption coefficient for 1e‐1hh transitions and a lower compressive strain accumulation; (ii) understanding that GaAs interlayers with thicknesses of just a few nanometers effectively extend the absorption edge without additional compressive strain and suppress lattice relaxation during growth; and (iii) understanding that GaAsP barriers should be thinner than 3 nm to facilitate tunneling transport and that their phosphorus content should be minimized while avoiding detrimental lattice relaxation. After structural optimization of 1.23‐eV bandgap quantum wells, a cell with 100‐period In_0.30GaAs(3.5 nm)/GaAs(2.7 nm)/GaAsP_0.40(3.0 nm) MQWs exhibited significantly improved performance, showing 16.2% AM 1.5 efficiency without an anti‐reflection coating, and a 70% internal quantum efficiency beyond the GaAs band edge. When compared with the GaAs control cell, the optimized cell showed an absolute enhancement in AM 1.5 efficiency, and 1.22 times higher efficiency with 38% current enhancement with an AM 1.5 cut‐off using a 665‐nm long‐pass filter, thus indicating the strong potential of MQW cells in Ge‐based 3‐J tandem devices. Copyright © 2013 John Wiley & Sons, Ltd.