Self-assembled lamellar MoS2, SnS2 and SiO2 semiconducting polymer nanocomposites

Lamellar nanocomposites based on semiconducting polymers incorporated into layered inorganic matrices are prepared by the co-assembly of organic and inorganic precursors. Semiconducting polymer-incorporated silica is prepared by introducing the semiconducting polymers into a tetrahydrofuran (THF)/water homogeneous sol solution containing silica precursor species and a surface-active agent. Semiconducting polymer-incorporated MoS(2) and SnS(2) are prepared by Li intercalation into the inorganic compound, exfoliation and restack in the presence of the semiconducting polymer. All lamellar nanocomposite films are organized in domains aligned parallel to the substrate surface plane. The incorporated polymers maintain their semiconducting properties, as evident from their optical absorption and photoluminescence spectra. The optoelectronic properties of the nanocomposites depend on the properties of both the inorganic host and the incorporated guest polymer as demonstrated by integrating the nanocomposite films into light-emitting diodes. Devices based on polymer-incorporated silica and polymer-incorporated MoS(2) show no diode behaviour and no light emission due to the insulating and metallic properties of the silica and MoS(2) hosts. In contrast, diode performance and electroluminescence are obtained from devices based on semiconducting polymer-incorporated semiconducting SnS(2), demonstrating that judicious selection of the composite components in combination with the optimization of material synthesis conditions allows new hierarchical structures to be tailored for electronic and optoelectronic applications.     

Dietary intake and stress fractures among elite male combat recruits

Background

We examined the effect of four weeks of ??-alanine supplementation on isometric endurance of the knee extensors at 45% maximal voluntary isometric contraction (MVIC).

Methods

Thirteen males (age 23?±?6 y; height 1.80?±?0.05?m; body mass 81.0?±?10.5?kg), matched for pre-supplementation isometric endurance, were allocated to either a placebo (n?=?6) or ??-alanine (n?=?7; 6.4?g·d^-1 over 4?weeks) supplementation group. Participants completed an isometric knee extension test (IKET) to fatigue, at an intensity of 45% MVIC, before and after supplementation. In addition, two habituation tests were completed in the week prior to the pre-supplementation test and a further practice test was completed in the week prior to the post-supplementation test. MVIC force, IKET hold-time, and impulse generated were recorded.

Results

IKET hold-time increased by 9.7?±?9.4?s (13.2%) and impulse by 3.7?±?1.3 kN·s^-1 (13.9%) following ??-alanine supplementation. These changes were significantly greater than those in the placebo group (IKET: t ₍₁₁₎?=?2.9, p ??0.05; impulse: t ₍₁₁₎?=?3.1, p????0.05). There were no significant changes in MVIC force in either group.

Conclusion

Four weeks of ??-alanine supplementation at 6.4?g·d^-1 improved endurance capacity of the knee extensors at 45% MVIC, which most likely results from improved pH regulation within the muscle cell as a result of elevated muscle carnosine levels.     

New Process for Recovery of Zinc Sulfate and Sulfuric Acid from Zinc Electrowinning Bleed Solutions

Acid-base couple extractants extract sulfuric acid and zinc sulfate efficiently, selectively and reversibly. Their properties allowed development of a new, solvent extraction process for treating zinc electrowinning waste streams. In this process, about 95% of the sulfuric acid and 95% of the zinc can be recovered at concentrations high enough to be directly recycled to zinc production. Lime consumption and gypsum formation are substantially reduced. Only one extractant is used in the process, and zinc is recovered as zinc sulfate.     

One‐Step Solvent‐Free Synthesis and Characterization of Zn1−xMnxSe@C Nanorods and Nanowires

The carbon‐encapsulated, Mn‐doped ZnSe (Zn_1−xMn_xSe@C) nanowires, nanorods, and nanoparticles are synthesized by the solvent‐free, one‐step RAPET (reactions under autogenic pressure at elevated temperature) approach. The aspect ratio of the nanowires/nanorods is altered according to the Mn/Zn atomic ratio, with the maximum being observed for Mn/Zn = 1:20. A 10–20 nm amorphous carbon shell is evidenced from electron microscopy analysis. The replacement of Zn by Mn in the Zn_1−xMn_xSe lattice is confirmed by the hyperfine splitting values in the electron paramagnetic resonance (EPR) experiments. Raman experiments reveal that the Zn_1−xMn_xSe core is highly crystalline, while the shell consists of disordered graphitic carbon. Variable‐temperature cathodoluminescence measurements are performed for all samples and show distinct ZnSe near‐band‐edge and Mn‐related emissions. An intense and broad Mn‐related emission at the largest Mn alloy composition of 19.9% is further consistent with an efficient incorporation of Mn within the host ZnSe lattice. The formation of the core/shell nanowires and nanorods in the absence of any template or structure‐directing agent is controlled kinetically by the Zn_1−xMn_xSe nucleus formation and subsequent carbon encapsulation. Mn replaces Zn mainly in the (111) plane and catalyzes the nanowire growth in the [111] direction.     

Extracellular Vesicle MicroRNA That Are Involved in β-Thalassemia Complications

Beta thalassemia major (βT) is a hereditary anemia characterized by transfusion-dependency, lifelong requirement of chelation, and organ dysfunction. MicroRNA (miRNA) can be packed into extracellular vesicles (EVs) that carry them to target cells. We explored EV-miRNA in βT and their pathophysiologic role. Circulating EVs were isolated from 35 βT-patients and 15 controls. EV miRNA was evaluated by nano-string technology and real-time quantitative polymerase chain reaction (RT-qPCR). We explored effects of EVs on cell culture proliferation, apoptosis, and signal transduction. Higher amounts of small EV (exosomes) were found in patients than in controls. The expression of 21 miRNA was > two-fold higher, and of 17 miRNA < three-fold lower in βT-EVs than control-EVs. RT-qPCR confirmed differential expression of six miRNAs in βT, particularly miR-144-3p, a regulator of erythropoiesis. Exposure of endothelial, liver Huh7, and pancreatic 1.1B4 cells to βT-EVs significantly reduced cell viability and increased cell apoptosis. βT-EV-induced endothelial cell apoptosis involved the MAPK/JNK signal-transduction pathway. In contrast, splenectomized βT-EVs induced proliferation of bone marrow mesenchymal stem cells (BM-MSC). In summary, the miR-144-3p was strongly increased; βT-EVs induced apoptosis and decreased endothelial, pancreatic, and liver cell survival while supporting BM-MSC proliferation. These mechanisms may contribute to βT organ dysfunction and complications.     

Effects of rating format on goal-setting dimensions: A field experiment.

Atotal of 10 managers and their 62 subordinates participated in a field experiment that examined the effects of performance appraisal feedback deriving from two rating formats—behavioral observation scales (BOS) and graphic rating scales—on three goal-setting dimensions. Multivariate analyses of variance and a priori t tests revealed, as hypothesized, that the BOS format yielded significantly higher levels of goal clarity, goal acceptance, and goal commitment, the three goal-setting dimensions. Results are discussed in terms of systemic characteristics, that is, a "built-in" focus on specific behaviors, rather than a translation of generic performance dimensions into specific work behaviors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Proposed thermodynamic method to determine the vortex mass in layered superconductors

We describe a simple method to study vortex dynamics that can determine or set an upper limit on the vortex mass. The specific heat of the vortex lattice in layered superconductors has a classical limit of 1 k_B per pancake vortex if the vortex mass is zero. If the vortex mass m_v is finite, a new Einstein branch of normal modes will appear with a crossover temperature E m_v ^–1, and the specific heat will saturate at a new classical limit of 2 k_B per pancake vortex.This work was supported in part by AFOSR under project F49620-92-C-0004 and by NSF under grant DMR 91-20361. We acknowledge helpful discussions with Shoucheng Zhang and S. R. Patel.     

Decidable fragments of many-sorted logic

Many natural specifications use types. We investigate the decidability of fragments of many-sorted first-order logic. We identified some decidable fragments and illustrated their usefulness by formalizing specifications considered in the literature. Often the intended interpretations of specifications are finite. We prove that the formulas in these fragments are valid iff they are valid over the finite structures. We extend these results to logics that allow a restricted form of transitive closure.     

Reflexive transitive invariant relations: A basis for computing loop functions

Invariant assertions play an important role in the analysis and verification of iterative programs. In this paper, we introduce a related but distinct concept, namely that of invariant relation. While invariant assertions are useful to prove the correctness of a loop with respect to a specification (represented by a precondition/ postcondition pair) in Hoare’s logic, invariant relations are useful to derive the function of the loop in Mills’ logic.