Structure and thickness optimization of active layer in nanoscale organic solar cells

 This paper presents the development of a two-dimensional model of multilayer bulk heterojunction organic nanoscale solar cells, consisting of the thickness of active layer and morphology of the device. The proposed model is utilized to optimize the device parameters in order to achieve the best performance using particle swarm optimization algorithm. The organic solar cells under research are from poly (3-hexylthiophene) and [6,6]-phenyl C61-butyric acid methyl ester type which are modelled to be investigated for performance enhancement. A three-dimensional fitness function is proposed involving domain size and active layer thickness as variables. The best results out of 20 runs of optimization show that the optimized value for domain size is 17 nm, while the short-circuit current vs. voltage characteristic shows a very good agreement with the experimental results obtained by previous researchers. © 2014 Springer Science+Business Media New York

A novel aggregate gene selection method for microarray data classification

This paper introduces a novel method for gene selection based on a modification of analytic hierarchy process (AHP). The modified AHP (MAHP) is able to deal with quantitative factors that are statistics of five individual gene ranking methods: two-sample t-test, entropy test, receiver operating characteristic curve, Wilcoxon test, and signal to noise ratio. The most prominent discriminant genes serve as inputs to a range of classifiers including linear discriminant analysis, k-nearest neighbors, probabilistic neural network, support vector machine, and multilayer perceptron. Gene subsets selected by MAHP are compared with those of four competing approaches: information gain, symmetrical uncertainty, Bhattacharyya distance and ReliefF. Four benchmark microarray datasets: diffuse large B-cell lymphoma, leukemia cancer, prostate and colon are utilized for experiments. As the number of samples in microarray data datasets are limited, the leave one out cross validation strategy is applied rather than the traditional cross validation. Experimental results demonstrate the significant dominance of the proposed MAHP against the competing methods in terms of both accuracy and stability. With a benefit of inexpensive computational cost, MAHP is useful for cancer diagnosis using DNA gene expression profiles in the real clinical practice.

Isotherm, kinetic, and thermodynamic equations for cefalexin removal from liquids using activated carbon synthesized from loofah sponge

Activated carbon (AC) developed from loofah sponge with phosphoric acid activation was applied to absorb cefalexin (CEX) in aqueous solution. AC was characterized by N2 adsorption–desorption isotherms and Fourier transform infrared spectroscopy (FTIR). Factors influencing the adsorption process were investigated. The equilibrium adsorption isotherms and kinetics of CEX were also studied. The results showed that AC prepared from loofah sponge had rough surface and abundant pores. The determination results of specific surface area (810.12 m²/g) and average pore size (5.28 nm) suggested the high adsorption capability. At low concentration, the AC could adsorb about 95% of CEX. The adsorption effect was independent of the temperature and pH. The maximum adsorption amount of CEX was about 55.11 mg/g at 308 K. The equilibrium data agreed well with Freundlich isotherm equation (R² = 0.9957) at 308 K, which indicated multilayer adsorption. FTIR analysis suggested the existence of phosphorus-containing functional groups, C–O bond, and C=C bond on the surface of AC of which the peak intensity of AC after adsorption was slightly lower after adsorption, indicating that the AC surface groups interacted with or were covered by the CEX species.

Synergistic effects of sodium lauroyl sarcosinate and glutamic acid in inhibition assembly against copper corrosion in acidic solution

© 2015 Elsevier B.V. All rights reserved. A self-assembled multilayer (SAM) from sodium lauroyl sarcosinate (SLS) and glutamic acid (GLU) is formed on copper surface. Its inhibition ability against copper corrosion is examined by electrochemical analysis and weight loss test. In comparison to SAM formed by just SLS or GLU, a synergistic effect is observed when the coexistence of SLS and GLU in SAM. The SLS/GLU SAM has an acicular multilayer structure, and SAM prepared under the condition of 5 mM SLS and 1 mM GLU shows the best protection efficiency. PM6 calculation reveals that the synergistic effect stems from interactions between SLS, GLU and cupric ions.

Strain gradients in Cu-Fe thin films and multilayers during micropillar compression

Plastic strain gradients can influence the work-hardening behaviour of metals due to the accumulation of geometrically necessary discolations at the micron/submicron scale. A finite element model based on the conventional theory of mechanism-based strain-gradient plasticity has been developed to simulate the micropillar compression of Cu–Fe thin films and multilayers. The modelling results show that the geometric constraints lead to inhomogeneous deformation in the Cu layers, which agrees well with the bulging of Cu layers observed experimentally. Plastic strain gradients develop inside the individual layers, leading to extra work-hardening due to the accumulation of geometrically necessary dislocations. In the multilayer specimens, the Cu layers deform more severely than the Fe layers, resulting in the development of tensile stresses in the Fe layers. It is proposed that these tensile stresses are responsible for the development of micro-cracks in the Fe layers.