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Crack detection is one of the important contents of the nuclear fuel pellet quality inspection. Aiming at the problem of high crack false detection rate caused by low image contrast of nuclear fuel...

The chemical-potential multiphase lattice Boltzmann method (CP-LBM) has the advantages of satisfying the thermodynamic consistency and Galilean invariance, and it realizes a very large density ratio and easily expresses the surface wettability. Compared with the traditional central difference scheme, the CP-LBM uses the Thomas algorithm to calculate the differences in the multiphase simulations, which significantly improves the calculation accuracy but increases the calculation complexity. In this study, we designed and implemented a parallel algorithm for the chemical-potential model on a graphic processing unit (GPU). Several strategies were used to optimize the GPU algorithm, such as coalesced access, instruction throughput, thread organization, memory access, and loop unrolling. Compared with dual-Xeon 5117 CPU server, our methods achieved 95 times speedup on an NVIDIA RTX 2080Ti GPU and 106 times speedup on an NVIDIA Tesla P100 GPU. When the algorithm was extended to the environment with dual NVIDIA Tesla P100 GPUs, 189 times speedup was achieved and the workload of each GPU reached 96%.

Photocatalytic materials are often used in the field of electrolysis of water for its competitive performance and low cost. This study describes the use of TiO2 for providing free electrons to prepare hydrated negative air ions together with the Lenard effect caused by air–water collision. The lifetime of HNAIs increased by 47.62% in comparison with the traditional corona discharge method; both the stability and the actual yield of the HNAIs increased significantly. The stability of HNAIs has a correlative relationship with the molecular weight and relative humidity. Lower mobility of the HNAIs with larger molecular weight results in low probability of collision with other air particles, making it relatively stable. Water molecules could form a water shell around the cluster ions in a high relative humidity environment, which can protect the ions, avoiding physical collision to extend the lifetime.

Suspensions of an elliptical particle in Poiseuille flow are investigated by using the multiple-relaxation-time lattice Boltzmann method coupled with the Galilean-invariant momentum exchange method. The elliptical particle shows lateral migration and final equilibrium, which are similar to the classical Segre–Silberberg effect. Because the elliptical shape interacts with the parabolic velocity distribution of the Poiseuille flow, the particulate behaviors remarkably contain regular wave accompanied by nonuniform rotation. When the blockage ratio grows up, the equilibrium position of the particle moves towards the channel centerline and the rotation period becomes long. With the increase of the aspect ratio, the rotation period becomes short; the equilibrium position shows a shape of saddle and reaches its bottom at nearby aspect ratio 0.5. Surprisingly, the numerical results show that the equilibrium position is insensitive to Reynolds number (Re) of Poiseuille flows in the range 3 ≤ R e ≤ 300 . This work can make active promotions to the researches of blood circulation of birds, whose red blood cell is oval or elliptical in shape.

This work focused on the chemisorption of volatile organic compounds (VOCs) on particulate matter of less than 2.5 μm (PM2.5). The detection results illustrated that VOCs on PM2.5 containing hydrox...

AgCl was incorporated with clay montmorillonite to improve the individual catalytic or adsorption performance. A green method was proposed to synthesize AgCl/montmorillonite composite by intercalating silver-ammonia complexes into the interlayers of montmorillonite followed by reacting with HCl vapor to in situ form AgCl particles on montmorillonite. The as-prepared samples were characterized by X-ray diffraction, scanning electron microscope, energy dispersive X-ray spectroscopy, transmission electron microscope, Brunauer–Emmett–Teller analysis, X-ray photoelectron spectra, and UV–vis diffuse reflectance spectrum. It was shown that AgCl not only intercalated into the interlamination of montmorillonite but also anchored on its exterior surfaces. AgCl on clay surface was cube-like particles, which were dominated by the higher activity of {1 0 0} planes. The photocatalytic activity of AgCl/montmorillonite (AgCl-Mt) composites were evaluated by degradation of azo dye Acid Red 18 (AR18) under UV-irradiation. AgCl in AgCl-Mt composites had an optimum amount. When 3CEC of silver-ammonia was used to prepare [Ag(NH3)2]+-exchanged Mt, the obtained 3AgCl-Mt had the best activity. The degradation of 50 mL AR18 at pH 6 with 1 g L−1 of catalyst only needed 10 min. The low pH and dye concentration, and high catalyst loading favored the removal of dye. Moreover, the superoxide radicals and holes were found to be major reactive species responsible for the photocatalytic degradation of AR18. PL revealed that besides reducing the aggregation of AgCl and tailoring morphology of AgCl, montmorillonite also suppressed the combination of photogenerated electron-hole pairs, and thus enhanced the photocatalytic activity and stability. This study may offer an efficient approach for fabricating silver-halide-based composite photocatalysts for environmental cleanup.

Contact angle is an essential characteristic in wetting, capillarity and moving contact line; however, although contact angle phenomena are effectively simulated, an accurate and real-time measurement for contact angle has not been well studied in computational fluid dynamics, especially in dynamic environments. Here, we design a geometry-based mesoscopic scheme for on-the-spot measurement of the contact angle in the lattice Boltzmann method. The measuring results without gravity effect are in good agreement with the benchmarks from the spherical cap method. The performances of the scheme are further verified in gravitational environments by simulating sessile and pendent droplets on smooth solid surfaces and dynamic contact angle hysteresis on chemically heterogeneous surfaces. This scheme is simple and computationally efficient. It requires only the local data and is independent of multiphase models.

A highly efficient Fenton-like catalyst was successfully developed by covalently immobilizing a Cu(II)–pyridine group complex onto silica microspheres. The catalyst was characterized by SEM, FTIR and XPS measurements. The catalytic activity was evaluated by heterogeneous degradation of Rhodamine B (RhB) with H2O2 in the dark. The effects of pH, catalyst loading, H2O2 concentration, initial dye concentration, and temperature on the degradation kinetics were investigated to optimize operational variables and find the potential mechanisms. It was found that the optimum pH of medium was near neutral, at which over 98% of RhB (5–7.5 mg L−1) was efficiently decolorized in 6 hours with 2 g L−1 catalyst and 200 mg L−1 H2O2. The TOC removal of RhB (10 mg L−1) also reached 72% after the reaction duration. Meanwhile, the acute toxicity of RhB to marine bacteria Vibrio fischeri was almost completely eliminated. The degradation of RhB could be well described with a pseudo-first order kinetic model. The reaction activation energy was approximately 38.60 kJ mol−1. Fluorescence analysis and free radical scavenging experiments were performed, and revealed that the hydroxyl radical was the main active species for RhB degradation. The stability of the catalyst was confirmed by insignificant leaching of copper species and loss of activity after four cycles. Based on these results and the literature, a possible mechanism for RhB degradation was proposed.

In this work we demonstrate that blood glucose can be controlled remotely through light stimulated release of insulin from an injected cutaneous depot. Human insulin was tethered to an insoluble but injectable polymer via a linker, which was based on the light cleavable di-methoxy nitrophenyl ethyl (DMNPE) group. This material was injected into the skin of streptozotocin-treated diabetic rats. We observed insulin being released into the bloodstream after a 2 min trans-cutaneous irradiation of this site by a compact LED light source. Control animals treated with the same material, but in which light was blocked from the site, showed no release of insulin into the bloodstream. We also demonstrate that additional pulses of light from the light source result in additional pulses of insulin being absorbed into circulation. A significant reduction in blood glucose was then observed. Together, these results demonstrate the feasibility of using light to allow for the continuously variable control of insulin release. This in turn has the potential to allow for the tight control of blood glucose without the invasiveness of insulin pumps and cannulas.

High solid content waterborne polyurethane-acrylate (WPUA) emulsions have been successfully synthesized in two steps. Firstly, we prepared a waterborne polyurethane emulsion, then reacted it with acrylate monomer by emulsion polymerization using the semi-continuous seeded method. The effects of the type and amount of emulsifier, the amount of dimethylolpropionic acid (DMPA), the choice of capping group, the ratio of PU/PA, and the method of adding a water-soluble monomer to the properties of the composite emulsion were investigated. The reactive emulsifier replaced the traditional emulsifier and there were no metal ions introduced to the reaction, whether by the emulsifier or the initiator. Through a variety of tests, we proved that the prepared emulsion has the advantages of small particle size, narrow distribution, good stability, good performance of the film, and solid content of 46%.

Chemical potential is an effective way to drive phase transition or express wettability. In this letter, we present a chemical-potential-based lattice Boltzmann model to simulate multiphase flows. The nonideal force is directly evaluated by a chemical potential. The model theoretically satisfies thermodynamics and Galilean invariance. The computational efficiency is improved owing to avoiding the calculation of pressure tensor. We have derived several chemical potentials of the popular equations of state from the free-energy density function. An effective chemical-potential boundary condition is implemented to investigate the wettability of a solid surface. Remarkably, the numerical results show that the contact angle can be linearly tuned by the surface chemical potential., 14 pages,2 figures

The stability of hydroxyl polyacrylate emulsion was studied from two aspects of the structure of latex particles and polymerization conditions. Waterborne polyacrylate was prepared through seeded semicontinuous emulsion polymerization method with pre-emulsification process. HEMA was used to provide a high content of hydroxyl group, and the reactive emulsifier SE-10 was introduced to substitute for the traditional emulsifier. The best conditions including polymerization process and temperature, monomer types and dropping time were determined, and the effects of emulsifier content and addition method, HEMA content, chain transfer agent content, and soft/hard monomer ratio on the properties of emulsion were investigated. Through the optimization of polymerization conditions and the control of the structure of particles, we have successfully synthesized the core-shell structure of polyacrylate emulsion with a good appearance, low viscosity and a solid content of 46.5%. The hydroxyl polyacrylate exhibits good performance, which has great potential in development and application. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 133, 44844.

This paper describes a lattice Boltzmann-based binary fluid model for inkjet printing. In this model, a time-dependent driving force is applied to actuate the droplet ejection. As a result, the actuation can be accurately controlled by adjusting the intensity and duration of the positive and negative forces, as well as the idle time. The present model was verified by reproducing the actual single droplet ejection process captured by fast imaging. This model was subsequently used to investigate droplet formation in piezoelectric inkjet printing. It was determined that wettability of the nozzle inner wall and the surface tension of the ink are vital factors controlling the print quality and speed. Increasing the contact angle of the nozzle inner delays the droplet breakup time and reduces the droplet velocity. In contrast, higher surface tension values promote earlier droplet breakup and faster drop velocity. These results indicate that the hydrophilic modification of the nozzle inner wall and the choice of inks with high surface tensions will improve printing quality., Comment: 15 pages, 7 figures, 4000 words

A high hydroxyl content waterborne polyester-acrylate emulsion was successfully synthesized in two steps. Firstly, the carboxyl terminated unsaturated polyester was synthesized, then it was reacted as a monomer with acrylate monomer by emulsion polymerization using the semi-continuous seeded method. The effects of the amount of hydroxyethyl methacrylate (HEMA), the ratio of polyester/acrylic, the ratio of soft/hard monomer, and the content of chain transfer agent to the properties of the composite emulsion were investigated. Through a variety of tests, both the emulsion and film properties of the composite emulsion were better than polyacrylate emulsion. The introduction of polyester improved the flexibility and impact resistance of hydroxyl acrylate film, and made the modified resin have advantages of both.

Antibiotics are emerging contaminants due to their potential risks to human health and ecosystems. Poor biodegradability makes it necessary to develop effective physical-chemical methods to eliminate these contaminants from water. The cobalt-modified MCM-41 was prepared by a one-pot hydrothermal method and characterized by SAXRD, N2 adsorption-desorption, SEM, UV–Vis DR, and FTIR spectroscopy. The results revealed that the prepared 3% Co-MCM-41 possessed mesoporous structure with BET surface areas at around 898.5 m2g−1. The adsorption performance of 3% Co-MCM-41 toward levofloxacin (LVF) was investigated by batch experiments. The adsorption of LVF on 3% Co-MCM-41 was very fast and reached equilibrium within 2 h. The adsorption kinetics followed the pseudo-second-order kinetic model with the second-order rate constants in the range of 0.00198–0.00391 g mg−1 min−1. The adsorption isotherms could be well represented by the Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherm equations. Nevertheless, D-R isotherm provided the best fit based on the coefficient of determination and average relative error values. The mean free energy of adsorption (E) calculated from D-R model was about 11 kJ mol−1, indicating that the adsorption was mainly governed by a chemisorption process. Moreover, the adsorption capacity was investigated as a function of pH, adsorbent dosage, LVF concentration, and temperature with help of respond surface methodology (RSM). A quadratic model was established, and an optimal condition was obtained as follows: pH 8.5, adsorbent dosage of 1 g L−1, initial LVF concentration of 119.8 mg L−1, and temperature of 31.6 °C. Under the optimal condition, the adsorption capacity of 3% Co-MCM-41 to LVF could reach about 108.1 mg g−1. The solution pH, adsorbent dosage, LVF concentration, and a combination of adsorbent dose and LVF concentration were significant factors affecting the adsorption process. The adsorption thermodynamic functions were also determined. The negative ΔH 0 (−33.50 kJ mol−1) and ΔS 0 (−43.57 J mol−1 K−1) suggested that the adsorption was an exothermic process accompanied by decreasing disorder. This study may indicate that 3% Co-MCM-41 is a promising adsorbent for removing emerging pollutants of LVF from water.

The electrical properties of WS2 nanotubes (NTs) were studied through measuring 59 devices. Important electrical parameters, such as the carrier concentration, mobility, and effective barrier height at the contacts, were obtained through fitting experimental non-linear I-V curves using a metal-semiconductor-metal model. The carrier mobility was found to be several orders of magnitude higher than that have been reported previously for WS2 NTs. Water absorption was found to decrease the conductivity and carrier mobility of the NTs, and could be removed when the sample was dried. Oxygen absorption also slightly decreased the conductivity of WS2 NTs.

We propose that a photodetector based on nanotubes formed from layered structure may have a faster response than nanowires or nanobelts. The layered compound tungsten disulfide (WS2) can absorb visible and near-infrared lights. We fabricated photodetectors based on individual WS2 nanotubes. The photodetectors exhibited a remarkable response to excitation with 633 and 785 nm light. The nanotube-based photodetectors exhibited short rise and decay times of a few hundred μs, high on/off ratio, and high spectral responsivity and external quantum efficiency. Our results imply that WS2 nanotubes are prospective candidates for high-performance nanoscale optoelectronic devices.

Individual WS(2) nanotubes (NTs) were bended and released in-situ inside a transmission electron microscope. Kinks appeared in the NTs suddenly during the bending process. Shell distortion, shell breaking and rotation of broken shells were observed in these kinks. Spontaneous self-healing and focused electron beam-assisted healing of the structure were observed after the load was removed. More importantly, the strength and electrical conductivity of the NTs were also restored to their original level when the structure recovered.