Simultaneous strength and ductility enhancements of high thermal conductive Ag7.5Cu alloy by selective laser melting

High electrical and thermal conductive metals (HETCM) play a key role in smart electronics, green energy, modern communications and healthcare, however, typical HETCM (e.g., Ag, Au, Cu) usually have relatively low mechanical strength, hindering further applications. Selective laser melting (SLM) is a potentially transformative manufacturing technology that is expected to address the issue. Ag is the metal with the highest thermal conductivity, which induces microscale grain refinement, but also leads to high internal stresses by SLM. Here, we select Ag7.5Cu alloy as an example to demonstrate that multi-scale (micro/meso/macro) synergies can take advantage of high thermal conductivity and internal stresses to effectively strengthen Ag alloy. The mimicry of metal-hardened structures (e.g., large-angle boundary) is extended to the mesoscale by controlling the laser energy density and laser scanning strategy to manipulate the macroscale internal stress intensity and mesoscale internal stress direction, respectively, to form mesoscale large-angle "grains", resulting in multiple mutual perpendicular shear bands during fracture. The presented approach achieved a significant enhancement of yield strength (+ 145%) and ductility (+ 28%) without post-treatment. The results not only break the strength-ductility trade-off of conventional SLM alloys, but also demonstrate a multi-scale synergistic enhancement strategy that exploits high thermal conductivity and internal stresses

Techno-economic analysis of optimal hybrid renewable energy systems – A case study for a campus microgrid

People are becoming more aware of the benefits of renewable energy. In recent years, a lot of research deals with the use of energy systems during on-grid or off-grid conditions, however, grid-connected systems may cause a power crisis to the grid. With the addition of renewable components, it is hard for the grid to keep balance. In hybrid systems, contradiction between net present cost (NPC) and excess electricity, unmet load, and capacity shortage always appears. Excess electricity, unmet load, and capacity shortage appear when the demand and supply are unbalanced, indicating the underutilization of energy. In this paper, we aim to overcome the aforementioned contradiction by conducting a case study for the first time on the implementation of a Hybrid Renewable Energy System (HRES) for a university campus in Selangor, Malaysia. Four different designs of HRES are proposed and compared. They are the Wind-Biogas-Battery System (Design A), Wind-Biogas-PV-Battery System (Design B), Wind-Biogas-Hydrogen Module-Battery System (Design C), Wind-Biogas-Diesel Generator-Battery System (Design D). The most optimal system will be selected based on the evaluation of three main criteria, i.e., cost analysis, electricity production analysis, and gas emission analysis

A robust method for determining DNA binding constants using capillary zone electrophoresis

Capillary zone electrophoresis (CZE or CE) with online UV detection was utilized to measure the binding constants between purified calf thymus DNA and a library of designed tetrapeptides which had been constructed using unnatural amino acids with thiazole ring side chains. Mixtures containing a constant amount of a tetrapeptide, the neutral marker (mesityl oxide), and varying concentrations of DNA were prepared and equilibrated at 8°C for 12 h. CE was then utilized to separate unbound tetrapeptides from the DNA- peptide complex. The UV absorbance of the peak representing unbound tetrapeptide decreased incrementally as a result of increasing the concentration of DNA in the equilibrium mixture. The absorbance of the peak corresponding to the unbound tetrapeptide was obtained directly from the electropherogram and used in the calculation of the DNA-peptide binding constants. The binding constant for each tetrapeptide to calf thymus DNA was obtained from the negative slope of a Scatchard plot and a comparison of the binding constants for different peptides showed that the tetrapeptides in the library have DNA-binding affinities ranging from 102 to 106 M-1

Boosting the Electrocatalytic Activity of Nickel-Iron Layered Double Hydroxide for the Oxygen Evolution Reaction byTerephthalic Acid

The development of a new type of oxygen evolution reaction (OER) catalyst to reduce the energy loss in the process of water electrolysis is of great significance to the realization of the industrialization of hydrogen energy storage. Herein, we report the catalysts of NiFe double-layer hydroxide (NiFe-LDH) mixed with different equivalent terephthalic acid (TPA), synthesized by the hydrothermal method. The catalyst synthesized with the use of the precursor solution containing one equivalent of TPA shows the best performance with the current density of 2 mA cm−2 at an overpotential of 270 mV, the Tafel slope of 40 mV dec−1, and excellent stable electrocatalytic performance for OER. These catalysts were characterized in a variety of methods. X-ray diffraction (XRD), Fourier Transform Infrared Spectrometer (FTIR), and Raman spectrum proved the presence of TPA in the catalysts. The lamellar structure and the uniform distribution of Ni and Fe in the catalysts were observed by a scanning electron microscope (SEM) and a transmission electron microscope (TEM). In X-ray photoelectron spectroscopy (XPS) of NiFe-LDH with and without TPA, the changes in the peak positions of Ni and Fe spectra indicate strong electronic interactions between TPA and Ni and Fe atoms. These results suggest that a certain amount of TPA can boost catalytic activity

New ferromagnetic (Fe1/3Co1/3Ni1/3)(80)(P1/2B1/2)(20) high entropy bulk metallic glass with superior magnetic and mechanical properties

New ferromagnetic (Fe1/3Co1/3Ni1/3)(80)(P1/2B1/2)(20) high entropy bulk metallic glass with superior magnetic and mechanical propertie

Fixed-Bed and Mobile-Bed Resistance of Channels with Steep Gradients in Mountainous Areas

Flood discharge and sediment transport are closely linked to channel resistance in steep mountain streams. Previous research has mainly focused on the resistance of fixed-bed channels with steep gradients and mobile-bed channels in alluvial rivers. The present study performs an experiment and establishes a calculation method for the fixed-bed resistance of mountain channels. The basic expression of the mobile-bed resistance of steep mountain channels is derived by determining the controlling factors of the bed load movement on the riverbed resistance. The proposed formula can accurately predict the variation of the bed load resistance. The results of the present research improve the understanding of fluid dynamics and sediment transport in steep mountain channels