Impact on aggregate/matrix bonding when a refractory contains zinc aluminate instead of spinel and magnesia-chrome

The high hot strength of MgO–Cr₂O₃ refractory is often ascribed to its intimate aggregate/matrix bonding. For a fundamental comparison with it, ∼2 mm aggregates of MgO and Al₂O₃ were separately embedded in ZnAl₂O₄ and MgAl₂O₄ matrices, sintered at 1600°C, and examined. It was found that similarity of thermal expansion coefficient (TEC) between the aggregate and the matrix is critical to achieve good bonding and this is more important than the extent of interdiffusion. The TEC mismatch of ≥5.7 × 10⁻⁶ K⁻¹ caused significant undesirable debonding in MgO aggregate/MgAl₂O₄ matrix sample and MgO/ZnAl₂O₄ despite >736 μm Zn²⁺ diffusion depth in the latter. Direct bonding, as inferred from a thicker interfacial reaction layer and a greater shift of the aggregate/matrix interface before and after firing, was better in MgAl₂O₄/ZnAl₂O₄ combination, followed by tabular Al₂O₃/ZnAl₂O₄ and Al₂O₃/MgAl₂O₄. Powder X-ray diffraction indicated that the volatilization of ZnAl₂O₄ at 1600°C in air was negligible compared to MgO–Cr₂O₃.     

Erosive wear behavior of spark plasma-sintered SiC–TaC composites

Spark plasma sintering of SiC-10, 20, or 30 wt% TaC composites was performed at 1800°C. Microstructures of sintered composites revealed uniform dispersion of TaC particles in SiC matrix. With the increase in TaC content, hardness decreased from 25.75 to 23.30 GPa and fracture toughness increased from 3.48 to 3.85 MPa m^1/2. Erosion testing was performed to evaluate the potential of sintered composites at room temperature and 400°C by a stream of SiC particles impinging at different angles (30°, 60°, or 90°). The erosion rate varied from 25 to 166 mm³/kg, with change in TaC content, impingement angle, or temperature. The erosion rate increased as the angle of impingement and temperature increased, but reduced when the TaC concentration increased. Worn surfaces revealed that the material was dominantly removed via fracture of SiC grains and TaC particles pull-out. SiC-30 wt% TaC composites exhibited superior erosive wear resistance at low impingement angle and room temperature.     

Recovery and purification of copper sulfide nanoparticles from acid mine drainage by biological sulfate reduction and microfiltration using low-cost ceramic membrane

Clean Technologies and Environmental Policy - Acid mine drainage (AMD) typically has a high amount of copper that can be recovered in pure form for different industrial applications. This study...     

UAV-IoT collaboration: Energy and time-saving task scheduling scheme

UAVs are capable of providing significant potential to IoT devices through sensors, cameras, GPS systems, and so forth. Therefore, the smart UAV-IoT collaborative system has become a current hot research topic. However, other concerns require in-depth investigation and study, such as resource allocation, security, privacy preservation, trajectory optimization, intelligent decision-making, energy harvesting, and so forth. Here, we suggest a task-scheduling method that splits IoT devices into distinct clusters based on physical proximity and saves time and energy. Cluster heads can apply an auto regressive moving average (ARMA) model to predict intelligently the timestamp of the arrival of the next task and associated estimated payments. Based on the overall expected payment, a cluster head can smartly advise the UAV about its time of next arrival. According to the findings of the simulation, the proposed ETTS algorithm significantly outperforms Task TSIE and TDMA-WS in terms of energy use (67%) and delays (36%).     

5’-Phosphorylation Increases the Efficacy of Nucleoside Inhibitors of the DNA Repair Enzyme SNM1A

Certain cancers exhibit upregulation of DNA interstrand crosslink repair pathways, which contributes to resistance to crosslinking chemotherapy drugs and poor prognoses. Inhibition of enzymes implicated in interstrand crosslink repair is therefore a promising strategy for improving the efficacy of cancer treatment. One such target enzyme is SNM1A, a zinc co-ordinating 5’–3’ exonuclease. Previous studies have demonstrated the feasibility of inhibiting SNM1A using modified nucleosides appended with zinc-binding groups. In this work, we sought to develop more effective SNM1A inhibitors by exploiting interactions with the phosphate-binding pocket adjacent to the enzyme's active site, in addition to the catalytic zinc ions. A series of nucleoside derivatives bearing phosphate moieties at the 5’-position, as well as zinc-binding groups at the 3’-position, were prepared and tested in gel-electrophoresis and real-time fluorescence assays. As well as investigating novel zinc-binding groups, we found that incorporation of a 5’-phosphate dramatically increased the potency of the inhibitors.     

Stable and fast oil recovery by environmentally friendly and easy to synthesize pristine graphitic carbon nitride

Clean Technologies and Environmental Policy - Fast oil recovery from the ocean after an oil spill is crucial before permanent damage happens to the ecological balance and marine life. Sorbents that...