Electrochemical performance of NixCo1-xMoO4 (0 ≤ x ≤ 1) nanowire anodes for lithium-ion batteries

NixCo1-xMoO4 (0 ≤ x ≤ 1) nanowire electrodes for lithium-ion rechargeable batteries have been synthesized via a hydrothermal method, followed by thermal post-annealing at 500°C for 2 h. The chemical composition of the nanowires was varied, and their morphological features and crystalline structures were characterized using field-emission scanning electron microscopy and X-ray powder diffraction. The reversible capacity of NiMoO4 and Ni0.75Co0.25MoO4 nanowire electrodes was larger (≈520 mA h/g after 20 cycles at a rate of 196 mA/g) than that of the other nanowires. This enhanced electrochemical performance of NixCo1-xMoO4 nanowires with high Ni content was ascribed to their larger surface area and efficient electron transport path facilitated by their one-dimensional nanostructure

Creep and Oxidation Behaviors of Alloy 617 in Air and Helium Environments at 1173K

AbstractCreep and oxidation behaviours of Alloy 617 in air and helium (He) environments at 1173K were comparatively investigated under different applied stress levels. There were no large differences in the shapes of the creep curves between the air and He environments. Creep rupture time in the He environment was shorter than that in air. The outer Cr-oxide thickness of the air specimens was thicker in short-tested duration than that of the He specimens. However, in the long- tested duration over 3,000h, the Cr-oxide thickness in the He environment was larger than in air. It was found that creep rupture life was closely related to the thickness of the outer Cr-oxide layer, because the form of the outer Cr-rich oxide layer brings about the Cr-depleted region which may deteriorate material strength or creep life

Microspinning: Local Surface Mixing via Rotation of Magnetic Microparticles for Efficient Small-Volume Bioassays

The need for high-throughput screening has led to the miniaturization of the reaction volume of the chamber in bioassays. As the reactor gets smaller, surface tension dominates the gravitational or inertial force, and mixing efficiency decreases in small-scale reactions. Because passive mixing by simple diffusion in tens of microliter-scale volumes takes a long time, active mixing is needed. Here, we report an efficient micromixing method using magnetically rotating microparticles with patterned magnetization induced by magnetic nanoparticle chains. Because the microparticles have magnetization patterning due to fabrication with magnetic nanoparticle chains, the microparticles can rotate along the external rotating magnetic field, causing micromixing. We validated the reaction efficiency by comparing this micromixing method with other mixing methods such as simple diffusion and the use of a rocking shaker at various working volumes. This method has the potential to be widely utilized in suspension assay technology as an efficient mixing strategy

Low-temperature synthesis of CuO-interlaced nanodiscs for lithium ion battery electrodes

In this study, we report the high-yield synthesis of 2-dimensional cupric oxide (CuO) nanodiscs through dehydrogenation of 1-dimensional Cu(OH)2 nanowires at 60°C. Most of the nanodiscs had a diameter of approximately 500 nm and a thickness of approximately 50 nm. After further prolonged reaction times, secondary irregular nanodiscs gradually grew vertically into regular nanodiscs. These CuO nanostructures were characterized using X-ray diffraction, transmission electron microscopy, and Brunauer-Emmett-Teller measurements. The possible growth mechanism of the interlaced disc CuO nanostructures is systematically discussed. The electrochemical performances of the CuO nanodisc electrodes were evaluated in detail using cyclic voltammetry and galvanostatic cycling. Furthermore, we demonstrate that the incorporation of multiwalled carbon nanotubes enables the enhanced reversible capacities and capacity retention of CuO nanodisc electrodes on cycling by offering more efficient electron transport paths

Characteristics of Soil Heavy Metal Contamination in the Intensive Livestock Farming Watersheds

Soil contamination of agricultural watersheds can increase to deteriorate water quality, human health, crop production and aquatic ecology. In particular, it is important to understand the impacts of soil heavy metal contamination from livestock excretion because the excretion has been gradually increasing due to the rapid growth of the livestock industry. In this study, to analyze the characteristics of soil heavy metal contamination in intensive livestock farming watersheds, we selected intensive livestock farming watersheds where livestock heads and amount of livestock excretion by species were spatiotemporally surveyed. We also investigated the characteristics of five soil heavy metals (As, Cd, Pb, Cu, Zn) contamination. The Cheongmi Stream watershed in Anseong, Kyungi-do and Gwangcheon Stream watershed in Hongseong, Chungcheongbuk-do, Korea were one of the most intensive livestock rearing regions where there were very large amounts of livestock excretion. It was also found that Cu and Zn among heavy metals exceeded the soil contamination concern standard at two of the sampling points in the Gwangcheon Stream watershed. Compared to the national soil measurement network data, it was showed that the concentrations of Cd, Cu, and Zn in the intensive livestock farming areas such as both Cheongmi Stream and Gwangcheon Stream watersheds were higher than in other areas. Thus, we suggested that the soil in intensive farming watersheds was contaminated by heavy metals compared to other areas. Therefore, it is necessary to manage not only livestock excretion, but also animals’ welfare, humans, and the environment to use less heavy metals in their feeds. We also believed that various impacts of livestock excretion on the environment need to be studied soon

Degree distributions under general node removal: Power-law or Poisson?

Perturbations made to networked systems may result in partial structural loss, such as a blackout in a power-grid system. Investigating the resultant disturbance in network properties is quintessential to understand real networks in action. The removal of nodes is a representative disturbance, but previous studies are seemingly contrasting about its effect on arguably the most fundamental network statistic, the degree distribution. The key question is about the functional form of the degree distributions that can be altered during node removal or sampling, which is decisive in the remaining subnetwork's static and dynamical properties. In this work, we clarify the situation by utilizing the relative entropies with respect to the reference distributions in the Poisson and power-law form. Introducing general sequential node removal processes with continuously different levels of hub protection to encompass a series of scenarios including random removal and preferred or protective removal of the hub, we classify the altered degree distributions starting from various power-law forms by comparing two relative entropy values. From the extensive investigation in various scenarios based on direct node-removal simulations and by solving the rate equation of degree distributions, we discover in the parameter space two distinct regimes, one where the degree distribution is closer to the power-law reference distribution and the other closer to the Poisson distribution.Comment: 12 pages, 7 figure

Reduced systemic vascular resistance is the underlying hemodynamic mechanism in nitrate-stimulated vasovagal syncope during head-up tilt-table test

AbstractBackgroundNitroglycerin (NTG) challenge during head-up tilt-table testing (HUTT) is often utilized to determine the etiology of unexplained vascular syncope. However, conflicting results concerning nitrate-induced hemodynamic changes during HUTT have been reported. The purpose of this study was to assess the determinants of presyncopal symptoms during NTG-stimulated HUTT.MethodsWe evaluated 40 patients with suspected vasovagal syncope. Beat-to-beat changes in blood pressure, heart rate (HR), cardiac index (CI), and systemic vascular resistance (SVR) during HUTT were measured with thoracic impedance cardiography and a plethysmographic finger arterial pressure monitoring device.ResultsNone of the 40 patients complained of presyncopal symptoms during passive HUTT. However, after the administration of NTG 28 patients showed presyncopal symptoms (NTG+ group) and the remaining 12 patients did not (NTG– group). HR, CI, and the stroke index did not significantly differ between the two groups, whereas mean arterial pressure and SVR were significantly lower in the NTG+ group.ConclusionsPresyncopal symptoms during NTG-stimulated HUTT are SVR mediated, not cardiac output mediated. This study challenges the conventional idea of a decrease in cardiac output mediated by NTG as the overriding cause of presyncopal symptoms during HUTT