Syntheses of nickel sulfides from 1,2-bis(diphenylphosphino)ethane nickel(II)dithiolates and their application in the oxygen evolution reaction

In this work, four heteroleptic Ni(II)dppe dithiolates complexes, [Ni(NED)(dppe)] (Ni-NED), [Ni(ecda)(dppe)] (Ni-ecda), [Ni(i-mnt)(dppe)] (Ni-i-mnt) and [Ni(cdc)(dppe)] (Ni-cdc) (dppe = 1,2-bis(diphenylphosphino)ethane; NED = 1-nitroethylene-2,2-dithiolate; ecda = 1-ethoxycarbonyl-1-cyanoethyelene-2,2-dithiolate; i-mnt = 1,1-dicyanoethylene-2,2-dithiolate and cdc = cyanodithioimidocarbonate), have been synthesized and characterized by analytical and spectroscopic techniques (Elemental analysis, vibrational, electronic absorption and multinuclear NMR spectroscopy). Structural characterization of all the four complexes by single crystal X-ray diffraction study suggests distortion in regular square planar geometry at Ni(II) center by coordination with two phosphorus of the dppe and two sulfur of the dithiolate ligands, respectively. The decomposition of all four complexes have been done to produce nickel sulfides and the resulting nickel sulfides have been utilized for electrocatalytic oxygen evolution reaction (OER). The nickel sulfide obtained by decomposing Ni-cdc shows best activity with overpotential η = 222 mV at j = 10 mA cm^?2 and a Tafel slope of 44.2 mV dec^?1 while other catalysts shows η > 470 mV at j = 5 mA cm^?2 and η > 600 mV at j = 10 mA cm^?2 at loading of 1.3 mg cm^?2.     

A variable neighbourhood search algorithm for the flexible job-shop scheduling problem

The flexible job-shop scheduling problem (FJSP) is a generalisation of the classical job-shop scheduling problem which allows an operation of each job to be executed by any machine out of a set of available machines. FJSP consists of two sub-problems which are assigning each operation to a machine out of a set of capable machines (routing sub-problem) and sequencing the assigned operations on the machines (sequencing sub-problem). This paper proposes a variable neighbourhood search (VNS) algorithm that solves the FJSP to minimise makespan. In the process of the presented algorithm, various neighbourhood structures related to assignment and sequencing problems are used for generating neighbouring solutions. To compare our algorithm with previous ones, an extensive computational study on 181 benchmark problems has been conducted. The results obtained from the presented algorithm are quite comparable to those obtained by the best-known algorithms for FJSP.     

Simultaneous optimisation of multiple performance characteristics in micro-EDM drilling of titanium alloy

Micro-electrical discharge machining (micro-EDM) has become a widely accepted non-traditional material removal process for machining conductive and difficult-to-cut materials effectively and economically. Being a difficult-to-cut material, titanium alloy suffers poor machinability for most cutting processes, especially the drilling of micro-holes using traditional machining methods. Although EDM is suitable for machining titanium alloys, selection of machining parameters for higher machining rate and accuracy is a challenging task in machining micro-holes. In this study, an attempt has been made for simultaneous optimization of the process performances like, metal removal rate, tool wear rate and overcut based on Taguchi methodology. Thus, the optimal micro-EDM process parameter settings have been found out for a set of desired performances. The process parameters considered in the study were pulse-on time, frequency, voltage and current while tungsten carbide electrode was used as a tool. Verification experiments have been carried out and the results have been provided to illustrate the effectiveness of this approach.     

Deoxynivalenol exposure assessment in a cohort of pregnant women from Bradford, UK

Deoxynivalenol (DON) is a ubiquitous contaminant of cereal crops in temperate regions of the world. It causes growth faltering and immune suppression in animals. Limited information is available on DON exposure in UK subpopulations. The objective of this study was to provide DON exposure assessment in a subset of pregnant women scheduled for an elective caesarean in a large multi-ethnic mother/infant birth cohort from Bradford, UK. Women aged 16-44 years (n = 85) provided a urine sample for DON analysis in the last trimester of pregnancy, and concurrently completed a food-frequency questionnaire (FFQ). The urinary DON biomarker was detected in all measured samples (geometric mean (GM)?= 10.3 ng DON mg(-1) creatinine, range = 0.5-116.7 ng mg(-1)). Levels were higher in women classified as South Asian in origin (GM: 15.2 ng mg(-1); 95% CI = 10.7-21.5 ng mg(-1)) compared with non-South Asians (GM = 8.6 ng mg(-1); 95% CI = 6.6-11.8 ng mg(-1)), p = 0.02). Estimated DON intake from FFQ data and typical levels of DON contamination of food suggest that this was mainly due to higher levels of exposure from bread, particularly daily intake of DON from chapattis in South Asians (estimated mean = 2.4 μg day(-1); 95% CI = 1.2, 3.7 μg day(-1)) compared with non-South Asians (estimated mean = 0.2 μg day(-1); 95% CI = 0-0.4 μg day(-1)), p < 0.001. This is the first biomarker demonstration of DON exposure in pregnant women, and several urinary DON levels were the highest ever recorded in any study. A larger survey within this birth cohort is warranted to investigate any potential risk to mothers and their babies, from DON exposure during pregnancy.     

On‐line system identification of structures using wavelet‐Hilbert transform and sparse component analysis

A new wavelet‐Hilbert transform based sparse component analysis (WHT‐SCA) method is presented for online system identification in indeterminate conditions. The instantaneous phase ratios of output signals are obtained by using a wavelet‐Hilbert transform based filter; and the out‐of‐phase data, that causes errors in identification accuracy, is detected and eliminated. Then, modal parameters of the structure are identified through existing relationships between the dispersion of filtered data in the frequency domain. Subsequently, to demonstrate the capability of the online identification, a new controller is introduced by combining the WHT‐SCA and a semi‐active tuned mass damper (STMD), resulting in creation of smart structures. The performance of the proposed method and controller is investigated through examples. The results demonstrate that, modal parameters of structures are identified accurately even with noise contamination and limited number of sensors. Also, the STMD is effectively robust against any variations in modal parameters of the structure.     

Flame spray synthesis of nano lanthanum strontium manganite for solid oxide fuel cell applications

Lanthanum strontium manganite is a classic cathode material for solid oxide fuel cells (SOFC). Nanosized LSM particles, due to their higher specfic surface area, have been found to enhance the electrode performance by providing a larger three phase boundary (TPB) area. However conventional processes like solid state, sol-gel or co-precipitation, produce particles having low specic surface area (< 8 m²/g) and hence require high sintering temperatures. Moreover these processes are multi-step and are hence time consuming. In the present work, single phase LSM with a crystallite size of 26 nm and a specfic surface area as high as 40 m²/g was produced by a flame spray pyrolysis method. The as-synthesized powder was characterized by X-ray diffraction (XRD), nitrogen adsorption, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Porous thin films were prepared by spin coating a water based dispersion of LSM. Electrochemical performance of the nanoparticulate cathode films were studied using impedance spectroscopy. Interfacial polarization resistance value of as low as 0.085 Ωcm ² at 850°C was obtained by this method. This method thus offers a very cost effective approach for the preparation of highly active cathode thin films for SOFC applications.     

Nondestructive Strength Assessment of In-Place Wood Utility Poles

In-place nondestructive simulation evaluation of the remaining bending strength of wooden utility poles is vital to the continued and successful operation of the poles, viability of the electrical transmission and delivery system, and reduction of system disruption potential. A methodology for nondestructively assessing the strength of in-place wood utility poles was developed and is proposed in this paper. Because of the nonhomogeneous and anisotropic nature of wood and the variability of in-place utility poles, a deterministic approach does not seem feasible. The proposed method combines multiple variables to statistically predict the breaking strength, or modulus of rupture, of wood poles. The full-scale testing methodology was tested on real life poles. Results from in-field simulation tests were correlated to data from failure testing of the full-scale poles. The proposed static bending approach is quite accurate, utilizing a device that applies a horizontal force on an in-place utility pole and measures the resulting deflection. The slope of the force-deflection curve and the pole moment of inertia from a regression analysis correlate well to the breaking strength of the poles. Additionally, a method for measuring and adjusting for the tilt of the utility pole under test was determined. Full-scale field simulated testing and break testing data that provide significant insight into nondestructive wood pole testing are provided in this paper. Recommendations for increasing the validity of the proposed model with additional test data, together with implementation of additional relevant parameters, are made.     

Morphological effects of Ni nanostructures on electropolymerization of aniline

Electrochemical polymerization of aniline on nanostructured Ni substrates was investigated. To this aim, the Ni substrate electrodes were prepared by casting various samples of Ni nanoparticles having different morphologies. The electropolymerization on these different nanostructured Ni substrates was systematically investigated by means of comparative results obtained from cyclic voltammetry and electron microscopy as representatives of electrochemical behavior and morphology, respectively. Since the Ni nanoparticles are the beginning sites for the polymer growth, polyaniline morphology is strongly controlled by the nature of the Ni nanoparticles associated with chemical properties rather than geometrical shape. In conclusions, although the substrate surfaces had a similar nanostructure, but due to the difference in their chemical properties, the morphologies electrochemical behaviors of the polyaniline films electrodeposited on these substrates are significantly different. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Comparative Study of Hysteresis Models in Immiscible Water Alternating Gas (WAG) Process

Abstract

To simulate multiphase flow in complex recovery processes such as water alternating gas (WAG), it is essential to consider the influences of saturation history on relative permeabilities and capillary pressures of the present phases. This effect, which is known as hysteresis, is generally handled by use of empirical models, and deciding which combinations of hysteresis options and parameters are appropriate for a specific study is required.

This study investigates how reservoir simulation results are influenced by the use of different modeling options for hysteresis effect in three-phase flow. Hysteresis models were categorized for wetting and nonwetting phases, and they were applied to relative permeability and capillary pressures. In addition, sensitivity analysis was performed on effective parameters on hysteresis behavior of relative permeability.

Laboratory hysteresis data were used in simulation of an immiscible WAG process. It was observed that including hysteresis options in simulation influenced the outputs significantly, mainly on oil recovery and breakthrough times (water and gas). Changing the type of nonwetting model had a negligible influence on the results, whereas the type of wetting hysteresis option had a considerable effect on prediction of recovery and breakthrough times. Furthermore, using hysteresis, capillary pressure was found to have a very weak effect on the outputs. Finally, it was observed that the significance of the hysteresis effect is very sensitive to imbibition residual saturation of oil in the presence of water.     

Pareto-optimal clustering scheme using data aggregation for wireless sensor networks

The presence of cluster heads (CHs) in a clustered wireless sensor network (WSN) leads to improved data aggregation and enhanced network lifetime. Thus, the selection of appropriate CHs in WSNs is a challenging task, which needs to be addressed. A multicriterion decision-making approach for the selection of CHs is presented using Pareto-optimal theory and technique for order preference by similarity to ideal solution (TOPSIS) methods. CHs are selected using three criteria including energy, cluster density and distance from the sink. The overall network lifetime in this method with 50% data aggregation after simulations is 81% higher than that of distributed hierarchical agglomerative clustering in similar environment and with same set of parameters. Optimum number of clusters is estimated using TOPSIS technique and found to be 9–11 for effective energy usage in WSNs.