Analysis of thermo-mechanical wear problems for reciprocal punch sliding

The relative sliding motion of two elastic bodies in contact induces wear process and contact shape evolution. In the case of a punch sliding on a substrate the transient process tends to a steady state for which the fixed contact stress and strain distribution develops in the contact zone. This state usually corresponds to a minimum of the wear dissipation power. The optimality conditions of the wear dissipation functional provide the contact stress distribution and the wear rate compatible with the rigid body punch motion. The present paper is aimed to extend the previous analyses [1], [2], [3], [4], [5] of steady state conditions to cases of periodic sliding of punch, assuming cyclic steady state conditions for both mechanical and thermal fields.     

Synthesis and electrochemical properties of nickel oxide/carbon nanofiber composites

The electrospinning of polyacrylonitrile (PAN) with a polyaniline and graphene sol–gel mixture produced uniform, smooth fibers with an average diameter of 0.3 μm. These electrospun fibers were stabilized for 2 h at 200 °C and then carbonized at 800 °C for 5 h. Composites were prepared by depositing Ni(OH)₂ on the carbon nanofibers (CNFs) and calcining them at different temperatures. The composites were characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The effect of the calcination temperatures on the electrochemical properties was studied using cyclic voltammetry and electrochemical impedance spectroscopy. The specific capacitance (SC) was found to be highest (738 F g⁻¹) at a calcination temperature of 400 °C. The charge transfer resistance (R_p) decreased as the calcination temperature was increased. However, the electrical double layer capacitance (EDLC) increased with an increase in the calcination temperature. The EDLC increased from 0.144 F g⁻¹ at a calcination temperature of 100 °C to 485 F g⁻¹ at a calcination temperature of 500 °C.     

Development of efficient docking strategies and structure-activity relationship study of the c-Met type II inhibitors

c-Met is a transmembrane receptor tyrosine kinase and an important therapeutic target for anticancer drugs. In the present study, we systematically investigated the influence of a range of parameters on the correlation between experimental and calculated binding free energies of type II c-Met inhibitors. We especially focused on evaluating the impact of different force fields, binding energy calculation methods, docking protocols, conformation sampling strategies, and conformations of the binding site captured in several crystallographic structures. Our results suggest that the force fields, the protein flexibility, and the selected conformation of the binding site substantially influence the correlation coefficient, while the sampling strategies and ensemble docking only mildly affect the prediction accuracy. Structure-activity relationship study suggests that the structural determinants to the high binding affinity of the type II inhibitors originate from its overall linear shape, hydrophobicity, and two conserved hydrogen bonds. Results from this study will form the basis for establishing an efficient computational docking approach for c-Met type II inhibitors design.     

The rapid selecting of precursor ions and product ions of thirty-four kinds of pesticide for content determination by GC–EI/MS/MS

Pesticide residues caused great threat to human body health, and all countries protected the health of human body by specifying its upper limit. However, pesticide residues were generally very low, similar to trace analysis and as low as millionth or less, the content determination of pesticide residues was a troublesome problem. With the application and promotion of tandem mass spectrometry, it was able to do trace analysis. GC–EI/MS/MS was a common method for the determination of pesticide residues. The multiple reaction monitoring (MRM) mode was the most common quantitative method used in GC–EI/MS/MS. It has the characteristics of high sensitivity, good reproducibility, high accuracy, strong anti-interference and high ion flux. Multiple-twin precursor ions, product ions and collision energy of thirty-four pesticides were provided for MRM. It could play an important role in developing MRM method for the quantifying of 34 kinds of pesticide. Meanwhile, the development of MRM method for the quantifying of other compounds could also refer to this paper.     

Unsupervised method for sentiment analysis in online texts

In recent years, the explosive growth of online media, such as blogs and social networking sites, has enabled individuals and organizations to write about their personal experiences and express opinions. Classifying these documents using a polarity metric is an arduous task. We propose a novel approach to predicting sentiment in online textual messages such as tweets and reviews, based on an unsupervised dependency parsing-based text classification method that leverages a variety of natural language processing techniques and sentiment features primarily derived from sentiment lexicons. These lexicons were created by means of a semiautomatic polarity expansion algorithm in order to improve accuracy in specific application domains. The results obtained for the Cornell Movie Review, Obama-McCain Debate and SemEval-2015 datasets confirm the competitive performance and the robustness of the system.     

Synthesis and characterization of microporous polymer microspheres with strong cation-exchange character

In this paper the synthesis and characterization of microporous polymer microspheres with ultra-high specific surface areas (>1000 m²/g) and strong cation-exchange character is described. The microspheres were synthesized by the hypercrosslinking of swellable precursor particles which had been produced by precipitation polymerization. The strong cation-exchange character, arising from the presence of sulfonic acid groups, was introduced through post-hypercrosslinking chemical modification reactions. Two alkyl sulfate reagents of differing polarity were compared as reagents for the sulfonation reactions, and a synthetic methodology was devised that allowed the sulfonic acid content of the microspheres to be controlled. Following a series of small-scale optimization experiments, optimized conditions were applied on a larger scale to the synthesis of three distinct polymers (HXLPP-SCX) tailored for use as strong cation-exchange (SCX) sorbents in solid-phase extraction (SPE) studies. All three polymers were in the form of polymer microspheres (mean particle diameters 3–5 μm) with relatively narrow particle size distributions and specific surface areas up to 1370 m²/g, and had tuneable ion-exchange capacities (IECs) ranging from 1.7–2.8 mmol/g.     

Clarification of Peritectic Reaction Between Diffusion and Heat Transfer Mechanisms in Sn-Ni Alloy Through Confocal Laser Scanning Microscopy

Metallurgical and Materials Transactions A - The nucleation and intermittent growth of peritectic Ni3Sn4 phase along the liquid/primary Ni3Sn2 interface were observed through high-temperature...     

Effect of sol–gel MgO spin-coating on the performance of TiO2-based dye-sensitized solar cells

This paper is concerned with the improvement of dye-sensitized solar cell (DSSC) efficiency upon MgO post-treatment of the TiO₂ electrode. A simple sol–gel technique, involving magnesium acetate as precursor, ethanol as solvent and nitric acid as stabilizer, is applied to prepare a solution of suspended MgO nanoparticles. A single drop of MgO sol at 0.1 M precursor concentration was spin-coated at 3000 rpm for 30 s onto the TiO₂ electrode and sintered at 500 K for 1 h. Dye-loading using N3-dye was applied for 6 h. An increase in the average efficiency of the DSSC from 2.5% to 3.9% (over 50% enhancement) was recorded. Measurements of the dark I–V characteristics, the open circuit voltage decays, the SEM images and the dye absorbance spectra, for both uncoated and MgO-coated electrodes were examined. The improvement of the DSSC efficiency was attributed to an upward shift of the TiO₂ flat band energy and a reduction of the rate of back-transport and recombination.