Droplet Evaporation on a Hydrophilic Mesh Considering Their Sunken Shapes in Holes

The evolution of droplet shapes on a hydrophilic copper mesh was studied by using high-speed microscopic imaging technology. When a water droplet wets a hydrophilic mesh, the liquid-vapor interface initially adopts a convex shape, named as the “first darkness”. Then, as the water evaporates, the liquid-vapor interface flattens, and then it gradually adopts a concave shape; meanwhile, a “second darkness” forms. Taking the shapes of droplets sunken in holes into consideration, the quantitative liquid-vapor interface area was acquired. The evaporation coefficient becomes lower and more reasonable when considering the area increase due to the pentahedron sunken liquid in the holes. A speculation was employed to understand the observed evaporation behavior and the overprediction of the evaporation coefficient.     

Facile preparation of NaV3O8/polytriphenylamine composites as cathode materials towards high-performance sodium storage

NaV₃O₈/polytriphenylamine composites were synthesized by an in situ oxypolymerization way for the first time. Among them, the NaV₃O₈/20 wt.% polytriphenylamine composite shows better cycling and rate performance. Its discharge capacity retains at 118.9 mAh g⁻¹ after 300 cycles at 120 mA g⁻¹. It also obtains a reversible capacity of 101.7 mAh g⁻¹ at 300 mA g⁻¹ after 100 cycles. These enhanced results arise from the excellent morphology, that is, smaller particles of clear edges and uniform distribution suppress the expansion and deformation of the crystal structure, and avoid large agglomerate particles gathering during the electrochemical reaction. In addition, tight polytriphenylamine (PTPAn) coating also improves the conductivity of NaV₃O₈ cathode and suppresses the dissolution of NaV₃O₈ in electrolyte.     

Reference Point Based Multi-Objective Optimization of Reservoir Operation: a Comparison of Three Algorithms

Traditional multi-objective evolutionary algorithms treat each objective equally and search randomly in all solution spaces without using preference information. This might reduce the search efficiency and quality of solutions preferred by decision makers, especially when solving problems with complicated properties or many objectives. Three reference point based algorithms which adopt preference information in optimization progress, e.g., R-NSGA-II, r-NSGA-II and g-NSGA-II, have been shown to be effective in finding more preferred solutions in theoretical test problems. However, more efforts are needed to test their effectiveness in real-world problems. This study conducts a comparison of the above three algorithms with a standard algorithm NSGA-II on a reservoir operation problem to demonstrate their performance in improving the search efficiency and quality of preferred solutions. Under the same calculation times of the objective functions, Pareto optimal solutions of the four algorithms are used in the empirical comparison in terms of the approximation to the preferred solutions. Three performance indicators are then adopted for further comparison. Results show that R-NSGA-II and r-NSGA-II can improve the search efficiency and quality of preferred solutions. The convergence and diversity of their solutions in the concerned region are better than NSGA-II, and the closeness degree to the reference point can be increased by 42.8%, and moreover the number of preferred solutions can be increased by more than 3 times when part of objectives are preferred. By contrast, g-NSGA-II shows worse performance. This study exhibits the performance of three reference point based algorithms and provides insights in algorithm selection for multi-objective reservoir optimization problems.

     

In Situ Investigation and Numerical Simulation of the Failure Depth of an Inclined Coal Seam Floor: A Case Study

Mine Water and the Environment - The 1131 working face of the Yangcheng coal mine was used for a research demonstration to study the failure characteristics of an inclined coal seam floor. A...     

Effect of Heat Treatment on Microstructure and Mechanical Properties of Alloy Mg – 10% Gd – 3% Y – 0.6% Zr

Metal Science and Heat Treatment - The microstructure, mechanical properties and fracture behavior of magnesium alloy Mg – 10% Gd – 3% Y – 0.6% Zr is studied in cast condition and...     

Polymer Template Synthesis of Flexible BaTiO3 Crystal Nanofibers

BaTiO₃ crystals are attractive materials due to their high dielectric properties, but they are brittle and inelastic ceramics, which limits their broader applications in emerging fields, such as flexible electronics. A scalable strategy for the fabrication of ultra‐flexible crystalline BaTiO₃ nanofiber (NF) films by a sol–gel electrospinning method, followed by a brief calcination, is reported. It facilitates the formation of perovskite BaTiO₃ crystals with intricate grain boundaries at a low temperatures by growing them within polymer NF templates. The ceramic films have a polymer‐like softness of 50 mN, a large Young's modulus of 61 MPa, and an elastic strain of 0.9%. Moreover, they have a low density of 28 mg cm^?3 and demonstrate superior softness without fracture after deformation. Piezoelectric sensors fabricated based on these films exhibit a high sensitivity of 80 ms with an output voltage of 1.05 V at a pressure of 100 kPa. This approach allows for the large‐scale fabrication of flexible BaTiO₃ crystal NF films.     

Systematic Control of the Orientation of Organic Phosphorescent Pt Complexes in Thin Films for Increased Optical Outcoupling

Orienting light‐emitting molecules relative to the substrate is an effective method to enhance the optical outcoupling of organic light‐emitting devices. Platinum(II) phosphorescent complexes enable facile control of the molecular alignment due to their planar structures. Here, the orientation of Pt(II) complexes during the growth of emissive layers is controlled by two different methods: modifying the molecular structure and using structural templating. Molecules whose structures are modified by adjusting the diketonate ligand of the Pt complex, dibenzo‐(f,h)quinoxaline Pt dipivaloylmethane, (dbx)Pt(dpm), show an ≈20% increased fraction of horizontally aligned transition dipole moments compared to (dbx)Pt(dpm) doped into a 4,4′‐bis(N‐carbazolyl)‐1,1′‐biphenyl, CBP, host. Alternatively, a template composed of highly ordered 3,4,9,10‐perylenetetracarboxylic dianhydride monolayers is predeposited to drive the alignment of a subsequently deposited emissive layer comprising (2,3,7,8,12,13,17,18‐octaethyl)‐21H,23H‐porphyrinplatinum(II) doped into triindolotriazine. This results in a 60% increase in horizontally aligned transition dipole moments compared to the film deposited in the absence of the template. The findings provide a systematic route for controlling molecular alignment during layer growth, and ultimately to increase the optical outcoupling in organic light‐emitting diodes.