A novel facile synthesis and characterization of molybdenum nanowires

We describe a straightforward technique to synthesize pure Mo nanowires (NWs) from Mo₆S_yI_z (8,2 <y + z ≤ 10) NWs as precursor templates. The structural transformations occur when Mo₆S_yI_z NWs are annealed in Ar/H₂ mixture leading to the formation of pure Mo NWs with similar structures as initial morphologies. Detailed microscopic characterizations show that large diameters (>15 nm) Mo NWs are highly porous, while small diameters (<7 nm) are made of solid nanocrystalline grains. We find NW of diameter 4 nm can carry up to 30 μA current without suffering structural degradation. Moreover, NWs can be elastically deformed over several cycles without signs of plastic deformation.     

Effects of structures of pyrolyzed corrin,corrole and porphyrin on oxygen reduction reaction

The effects of the structures of various pyrolyzed cobalt-based macrocyclic compounds, which are pyrolyzed cobalt-corrin compounds (py-Co-Corrin/C), pyrolyzed cobalt-corrole compounds (py-Co-Corrole/C) and pyrolyzed cobalt-porphyrin compounds (py-Co-Porphyrin/C), on their activities in the oxygen reduction reaction (ORR) are studied. Following the pyrolysis, py-Co-Corrin/C has a higher ORR activity than py-Co-Corrole/C and py-Co-Porphyrin/C, which their electron-transfer numbers are 3.90, 3.87 and 3.37 at 0.3 V, respectively. According to the analysis of near edge X-ray absorption fine structure in N K-edge, only py-Co-Corrin/C has the Co–N₄ chelate and poly-aromatic hydrocarbons when pyrolyzed at high temperature. The X-ray absorption spectra reveal the oxidation states of central cobalt in cobalt-based macrocyclic compounds which are changed from high to low. Also, the atomic distances of cobalt to its neighbors vary among all of the samples. The experimental results suggest that the structure and the coordination of cobalt-based macrocyclic compounds strongly affect their ORR activities.     

A Modified Method Based on the Discrete Sliding Norm Transform to Reduce the PAPR in OFDM Systems

Orthogonal frequency division multiplexing (OFDM) is a modulation technique that allows the transmission of high data rates over wideband radio channels subject to frequency selective fading by dividing the data into several narrowband and flat fading channels. OFDM has high spectral efficiency and channel robustness. However, a major drawback of OFDM is that the peak‐to‐average power ratio (PAPR) of the transmitted signals is high, which causes nonlinear distortion in the received data and reduces the efficiency of the high power amplifier in the transmitter. The most straightforward method to solve this problem is to use a nonlinear mapping algorithm to transform the signal into a new signal that has a smaller PAPR. One of the latest nonlinear methods proposed to reduce the PAPR is the L₂‐by‐3 algorithm, which is based on the discrete sliding norm transform. In this paper, a new algorithm based on the L₂‐by‐3 method is proposed. The proposed method is very simple and has a low complexity analysis. Simulation results show that the proposed method performs better, has better power spectral density, and is less sensitive to the modulation type and number of subcarriers than L₂‐by‐3.     

Active–reactive power approaches for optimal placement of charge stations in power systems

Electric Vehicles (EVs) have been suggested as alternatives to conventional vehicles for reducing petrol consumption and carbon dioxide (CO₂) emissions. When a large number of EVs connect to the grid, they can cause a large amount of power loss. Where to install multiple charge stations in the grid, so as to mitigate losses caused by EVs when providing energy to those EVs, is becoming vitally important. In this paper, a distribution test-network model is described. A new analytical method is proposed, using the stations’ cooperation in terms of optimal active and reactive power dispatch as well as power flow analysis for locating the optimal placement of charge stations, so as to reduce power losses. This method is compared with the previously developed current density method for single charge stations using system simulation results. It was demonstrated that the methods proposed in this paper are more accurate than the current density method, and that 17% of the average active power loss can be saved for three different types of load profile. In addition, 27% of the average active power loss was saved by installing two charge stations rather than no charge stations in the test-line. It is shown that this could represent a 2.6% annual yield above inflation for investing in installing and running such charge stations.     

Highly active Pt decorated Pd/C nanocatalysts for oxygen reduction reaction

This article describes findings of the correlation between the atomic scale surface structure and the electrocatalytic performance of nanoengineered Pt-Pd/C catalysts for oxygen reduction reaction (ORR), aiming at providing a new fundamental insight into the role of the detailed atomic decorated structure of the catalysts in fuel cell reactions. Carbon-supported Pt decorated Pd nanoparticles (donated as Pt-Pd/C), with Pt coverage close to a monolayer, were prepared from a simple galvanic replacement reaction between Pd/C particles and PtCl₄^2? at room temperature. The decorated architecture was confirmed by extensive microstructural characterization techniques, including TEM, XRD, XPS, HAADF-STEM, ICP and HS-LEIS. The catalysts were also examined for their intrinsic kinetic activities towards oxygen reduction reaction. The results have shown that the Pt-Pd/C catalysts are highly active towards molecular oxygen electrocatalytic reduction. These findings have profound implications to the design and nanoengineering of decorated surfaces of catalysts for oxygen reduction reaction.     

Photocatalytic conversion of CO2 into methanol using graphitic carbon nitride under solar,UV laser and broadband radiations

Photocatalytic conversion of carbon dioxide into methanol using highly efficient g‐C₃N₄, in conjunction with three different radiations (solar radiation, broad‐band ultraviolet (UV)–visible lamp, and laser beam) is presented. The optical, structural, and morphological properties of the synthesized g‐C₃N₄ were studied using advanced analytical techniques like Fourier transform infrared spectroscopy, UV–visible spectrometer, X‐ray diffraction, high‐resolution transmission electron microscopy, high‐angle annular dark field, and X‐ray photoelectron spectroscopy. The relative merits of the three sources of radiation in the presence of g‐C₃N₄ were studied in terms of key figures of merit of the photocatalytic process, namely, methanol production yield and quantum yield. As expected, after 40 min of irradiation, 355‐nm laser (40 mJ/pulse, 10 Hz) with g‐C₃N₄ rendered the best methanol production yield (510 μmol g ^{? 1} h ^{? 1}), followed by solar radiation (130 μmol g ^{? 1} h ^{? 1}), and UV broadband lamp. This indicates that the photon flux and the spectral properties of incident light are the key factors for the enhancement of methanol production yield. Although the methanol production yield with 355‐nm laser radiation is quite impressive because of the inherent high photon flux and the monochromatic nature of laser, the methanol yield of 130 μmol g ^{? 1} h ^{? 1} with natural sunlight is quite an important result, as it can be used for the development of large‐scale solar fuel generation facilities by harnessing the naturally abundant solar radiation. Copyright © 2017 John Wiley & Sons, Ltd.     

Consumer acceptance of reformulated food products: A systematic review and meta-analysis of salt-reduced foods

Food product reformulation is promoted as an effective strategy to reduce population salt intake and address the associated burden of chronic disease. Salt has a number of functions in food processing, including impacting upon physical and sensory properties. Manufacturers must ensure that reformulation of foods to reduce salt does not compromise consumer acceptability.

The aim of this systematic review is to determine to what extent foods can be reduced in salt without detrimental effect on consumer acceptability.

Fifty studies reported on salt reduction, replacement or compensation in processed meats, breads, cheeses, soups, and miscellaneous products. For each product category, levels of salt reduction were collapsed into four groups: <40%, 40–59%, 60–79% and ≥80%. Random effects meta-analyses conducted on salt-reduced products showed that salt could be reduced by approximately 40% in breads [mean change in acceptability for reduction <40% (?0.27, 95% confidence interval (CI) ?0.62, 0.08; p = 0.13)] and approximately 70% in processed meats [mean change in acceptability for reductions 60–69% (?0.18, 95% CI ?0.44, 0.07; p = 0.15)] without significantly impacting consumer acceptability. Results varied for other products.

These results will support manufacturers to make greater reductions in salt when reformulating food products, which in turn will contribute to a healthier food supply.     

Improving bit error rate under burst noise in OFDM power line communications

Noise in Power Line Communications is typically impulsive, with impulses being a fraction of the OFDM symbol length. Because of their large duration the impulse can also be called bursts. The short duration of the burst compared with the OFDM symbol length implies that there is a strong correlation between the noise at different carriers, given a determined burst position. The position can be determined using an estimate of the noise after a first demodulation. The high correlation is used to develop demodulators with a reduced bit error rate in comparison with conventional demodulators, so increasing the capacity. The demodulators use a smoothed estimate of the noise signal or a new metric for the distance based on the new correlation matrix. About half of the bit errors can be corrected in this way, corresponding to a 1 dB improvement in Signal Noise Ratio (SNR). How to split the OFDM symbol without increasing the overhead due to the circular prefix is also shown. Noise measurements in power lines are presented. These measurements are used in the simulations.     

Estimation of biosurfactant yield produced by Klebseilla sp. FKOD36 bacteria using artificial neural network approach

Environmental and medium parameters estimation is an essential step in Bioprocess engineering. In the present study, artificial neural network (ANN) was employed in estimation of biosurfactants yield from bacterial strain Klebseilla sp. FKOD36, surface tension reduction as well emulsification index. The data obtained from experimental design were used in modelling and optimization of ANN method. Temperature, pH value, incubation period, carbon, nitrogen and hydrocarbon sources were used as input of ANN model independently in the prediction of biosurfactants yield, surface tension reduction and emulsification index. Using the optimized values of critical input elements of ANN, the experimental values of biosurfactant yield, emulsification index and surface tension showed close agreement with the model estimate. The most efficient ANN model assessment was 0.030 g/l for actual value 0.038 g/l of biosurfactant yield, 31.67% for actual value 31.68% of emulsification index, and 21.6 dyne/cm for actual value 21.5 dyne/cm of surface tension respectively.     

高炉入炉焦比影响因素的分析与应用

本文统计了莱钢2#高炉生产情况,分析了制约入炉焦比的因素,制定了解决措施。通过优化,成功将炉焦比进一步降低,取得了良好效果,经济效益显著。