Effect of methane concentration on physical properties of diamond-coated cemented carbide tool inserts obtained by hot-filament chemical vapour deposition

Diamond-coated tools can greatly improve the productivity of machining highly abrasive materials such as high silicon–aluminium alloys used in the automotive industry. Cemented-carbide diamond-coated tool inserts have not become an off-the-shelf product owing to several difficulties including insufficient adhesion of diamond to the substrate and questionable reproducibilty in their machining performance in the manufacturing. In order to overcome these difficulties, a better understanding of the effects of the chemical vapour deposition (CVD) conditions such as methane concentration, reactor pressure and substrate temperature is important. In this work, cemented tungsten carbide tool inserts with 6 wt% Co (WC–Co) were coated with diamond films deposited at five different methane concentrations (1–9 vol%). Here we present preliminary results of the effect of methane concentration variation on the following physical properties of the diamond coating: surface morphology; crystal structure; chemical quality; surface roughness; residual stress. The results indicate that the best physical properties of diamond-coated tool inserts using hot-filament CVD are achieved with diamond coatings deposited at methane concentrations ranging from 1 to 3%.     

Information processing in recovered depressed children and adolescents

Previous research into subjective probability estimates for negative events revealed that depressed children estimated events as equally likely to happen to themselves as to other children. In contrast, both controls and anxious children estimated that negative events were more likely to happen to others than to themselves. The present study followed up this finding by investigating the subjective probability judgements concerning future negative events generated by children and adolescents who have recovered from depression. Subjects generated probability estimates either for themselves or for other children for a range of negative events on a visual analogue scale. The results revealed that both recovered depressed and matched control groups estimated negative events as significantly more likely to happen to others than to themselves. It was also found that the recovered depressed subjects estimated that negative events were less likely overall, compared to the controls. These results are discussed in the context of the adult literature.     

Determining the optimum replacement policy for Holstein dairy herds in Iran

The objective of this study was to determine the optimum replacement policy for Holstein dairy herds in Iran using a dynamic programming model. Cows were described in terms of state variables that included milk production class, parity, pregnancy status, and month in milk with a 1-mo stage length. The objective function maximized the net present value of cows over a 15-yr planning horizon. Markov simulation was used to estimate expected herd dynamics under the optimal decision plan determined by dynamic programming. Stochastic elements included probabilities of pregnancy and abortion, production level, and involuntary culling. The optimum annual culling rate was estimated to be 31.4%, and cows had an expected herd life (time from first calving until culling) of 3.18 yr. High replacement cost and low carcass value resulted in only 2.87% voluntary culling (i.e., optimal model-based replacement). Assuming a heat detection rate of 0.4, cows averaged 2.8 services per lactation under the optimal policy. Sensitivity analyses were carried out to evaluate the effect of milk price, herd-average production, feed cost, heifer price, and carcass value on optimum replacement decisions. Herd-average production, replacement cost, and risk of involuntary culling were important factors affecting the optimal culling policy. Changes in the price of feed, calves, and milk and the probability of pregnancy had no considerable effect on the optimal policy considering the market situation in Iran during 2008.     

Effect of ultrasound- and pulsed electric field-assisted enzymatic treatment on the recovery and quality of sunflower oil

The aim of this study was to evaluate the effect of cavitation and electroporation on enzymolysis extraction of sunflower oil. The optimum extraction conditions during 2 h under enzyme-assisted extraction (EAE) with a maximum oil yield of ≈23.70 ± 0.11% were as follows: cellulase/pectinase ratio 2:1, enzyme concentration 2%, pH 4.5, liquid/solid ratio 6:1 ml/g, and extraction temperature 40°C. Under the optimized enzymatic conditions, the application of ultrasound- (250 W) and pulsed electric field- (1.2 kV/cm; 52.4 kJ/kg) assisted enzymatic extraction for 30 min significantly increased the oil extraction yield by 91.1% and 18.6%, respectively, as compared with EAE.     

Fast and Ultraclean Approach for Measuring the Transport Properties of Carbon Nanotubes

In this work, a fast approach for the fabrication of hundreds of ultraclean field‐effect transistors (FETs) is introduced, using single‐walled carbon nanotubes (SWCNTs). The synthesis of the nanomaterial is performed by floating‐catalyst chemical vapor deposition, which is employed to fabricate high‐performance thin‐film transistors. Combined with palladium metal bottom contacts, the transport properties of individual SWCNTs are directly unveiled. The resulting SWCNT‐based FETs exhibit a mean field‐effect mobility, which is 3.3 times higher than that of high‐quality solution‐processed CNTs. This demonstrates that the hereby used SWCNTs are superior to comparable materials in terms of their transport properties. In particular, the on–off current ratios reach over 30 million. Thus, this method enables a fast, detailed, and reliable characterization of intrinsic properties of nanomaterials. The obtained ultraclean SWCNT‐based FETs shed light on further study of contamination‐free SWCNTs on various metal contacts and substrates.     

A robust scheduling for the multi-mode project scheduling problem with a given deadline under uncertainty of activity duration

The problem of this paper deals with the multi-mode project scheduling problem under uncertainty of activity duration where only the renewable resources are taken into account and a given deadline has to be met at the cost of recruiting additional resources. A heuristic algorithm is employed to solve this problem, and to maintain the robustness of the baseline schedule, the concept of critical chain project management (CCPM) is applied in which a new definition to resource buffer is considered. A simulation methodology is used to determine the size and location of resource buffers in the schedules in which three different buffer sizes and three different uncertainty levels are considered. Results and analysis of the simulation outcomes illustrate that resource buffers are useful and should be simulated by the CCPM schedules, as they help to decrease the total duration of the project during implementation and meet the deadline of the project with more assurance.     

Optical and photocatalytic properties of the Fe-doped TiO2 nanoparticles loaded on the activated carbon

In this work, Fe-doped (1?wt%) TiO₂ loaded on the activated carbon nano-composite was prepared using a sol-gel method. A prepared nano-composite was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), BET surface area, Fourier transform infrared spectroscopy (FTIR), photoluminescence (PL) spectroscopy and UV–Vis diffuse reflectance spectroscopy (DRS). The photocatalytic activity of the nano-composite was evaluated through degradation of synthetic textile wastewater, reactive red 198, under visible light irradiations. The XRD result indicated that the TiO₂ nano-composite contained only anatase phase. The surface area of the TiO₂ increased from 48?m²/g to 100?m²/g through the fabrication of the nano-composite. The FE-SEM results indicate that the TiO₂ particles with an average particle size of 35–70?nm can be deposited homogeneously on the activated carbon surface. DRS showed that the Fe doping in the TiO₂ -activated carbon nano-composite induced a significant red shift of the absorption edge and then the band gap energy decreased from 3.3 to 2.9?eV. Photocatalytic results indicated that the photocatalytic activity of the Fe doped TiO₂ increased under visible light irradiation in the presence of the activated carbon.     

Highly Conductive Ti3C2Tx MXene Hybrid Fibers for Flexible and Elastic Fiber‐Shaped Supercapacitors

Fiber‐shaped supercapacitors (FSCs) are promising energy storage solutions for powering miniaturized or wearable electronics. However, the scalable fabrication of fiber electrodes with high electrical conductivity and excellent energy storage performance for use in FSCs remains a challenge. Here, an easily scalable one‐step wet‐spinning approach is reported to fabricate highly conductive fibers using hybrid formulations of Ti₃C₂T_x MXene nanosheets and poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate. This approach produces fibers with a record conductivity of ≈1489 S cm^?1, which is about five times higher than other reported Ti₃C₂T_x MXene‐based fibers (up to ≈290 S cm^?1). The hybrid fiber at ≈70 wt% MXene shows a high volumetric capacitance (≈614.5 F cm^?3 at 5 mV s^?1) and an excellent rate performance (≈375.2 F cm^?3 at 1000 mV s^?1). When assembled into a free‐standing FSC, the energy and power densities of the device reach ≈7.13 Wh cm^?3 and ≈8249 mW cm^?3, respectively. The excellent strength and flexibility of the hybrid fibers allow them to be wrapped on a silicone elastomer fiber to achieve an elastic FSC with 96% capacitance retention when cyclically stretched to 100% strain. This work demonstrates the potential of MXene‐based fiber electrodes and their scalable production for fiber‐based energy storage applications.