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The process of superhard particle breakage in the grinding zone of the fluidized bed opposed jet mill is investigated using the CFD-DEM (computational fluid dynamics-discrete element method) coupling method with the Tavares UFRJ Breakage Model in the present study. The effects of structural and operational parameters, such as target plate structure, nozzle position, air inlet velocity, and feed rate, on the equipment stress distribution, airflow velocity, pressure field, particle velocity, and cumulative particle size distribution are thoroughly studied to determine the optimal structural and operational parameters. Experimental validation is conducted, including scanning electron microscope (SEM) observation of particle morphology and analysis of particle size distribution of ground product particles. The simulation results indicate that the wear rate of the structure without a target plate is lower than that of the structure with a target plate in the grinding central zone. Therefore, the structure without a target plate is chosen for further investigation. The cumulative particle size distribution after grinding is influenced by nozzle position, air inlet velocity, and feed rate. The particle D50 is positively correlated with nozzle spacing and feed rate, while it is negatively correlated with air inlet velocity. The optimal grinding effect is achieved when the distance between the nozzle and the center of the grinding zone ranges from 52.5 mm to 72.55 mm, the air inlet velocity is 950 m/s, and the feed rate is 10.5 g/s. Through experimental investigation, it has been observed that when the feed rate is 10 g/s, the particle size distribution becomes more uniform. Furthermore, consistent trends in the cumulative particle size distribution in the experiment and simulation results can be found, which validates the present numerical model. It was observed that particles at low feed rates retain certain angular edges, while particle roundness increases at high feed rates. [ABSTRACT FROM AUTHOR]

Pressure nozzles are widely used in spray drying and other industries. In order to improve the atomization characteristics of pressure cyclone nozzles, a new type of annular jet gas impingement atomization device is developed. We use high-speed imaging and digital image processing and other methods to analyze the spray characteristics of the different annular device configurations (using four, six, and eight tubes) and under different gas–liquid mass flow rates. It is shown that with an increase in the Air–Liquid mass Ratio (ALR), the liquid film breakup process changes from undulating sheet breakup to perforated sheet breakup and the breakup length decreases. The breakup length decreases the most under the condition of six-tube airflow with the range of 31–55%, while the Sauter mean diameter (SMD) basically does not change. With the increase in ALR and the Weber number of liquid (Wel), the droplet size distribution becomes more uniform. The spray characteristics of the atomizer assisted by gas jets reaches the best state when Wel = 4596.3 and m ˙ g = 1.97 g/s. The experimental conclusions have some guiding significance for the design and optimization of the atomization devices in spray drying towers. [ABSTRACT FROM AUTHOR]

Manganese dioxide (MnO2) has been extensively investigated as an electrode material for supercapacitors because of its high theoretical capacitance, great abundance, and low toxicity. To obtain satisfactory capacitance performance, in recent years, many efforts have been dedicated to the fabrication of MnO2 nanoparticles that offer a larger specific surface area and an escalated chemical activity. Beyond them, the ideal dispersibility of nanoparticles in a liquid medium is also of vital importance when processing those powdery materials into slurry ones for some particular uses, such as editable and ink‐printing supercapacitor devices. In this study, the as‐synthesized ultrafine MnO2 nanoparticles having excellent dispersibility in water can be prepared via a facile one‐step hydrothermal route, with a uniform size in diameter of 200 nm exhibiting a large specific surface area of ~389.7 m2 g−1, and a high specific capacitance of 135.7 F g−1 at 5 mV s−1. [ABSTRACT FROM AUTHOR]

Many insects, including the Plutella xylostella (L.), have developed varying degrees of resistance to many insecticides, including Bacillus thuringiensis (Bt) toxins, the bioinsecticides derived from Bt. The polycalin protein is one of the potential receptors for Bt toxins, and previous studies have confirmed that the Cry1Ac toxin can bind to the polycalin protein of P. xylostella, but whether polycalin is associated with the resistance of Bt toxins remains controversial. In this study, we compared the midgut of larvae from Cry1Ac-susceptible and -resistant strains, and found that the expression of the Pxpolycalin gene was largely reduced in the midgut of the resistant strains. Moreover, the spatial and temporal expression patterns of Pxpolycalin showed that it was mainly expressed in the larval stage and midgut tissue. However, genetic linkage experiments showed that the Pxpolycalin gene and its transcript level were not linked to Cry1Ac resistance, whereas both the PxABCC2 gene and its transcript levels were linked to Cry1Ac resistance. The larvae fed on a diet containing the Cry1Ac toxin showed no significant change in the expression of the Pxpolycalin gene in a short term. Furthermore, the knockout of polycalin and ATP-binding cassette transporter subfamily C2 (ABCC2) genes separately by CRISPR/Cas9 technology resulted in resistance to decreased susceptibility to Cry1Ac toxin. Our results provide new insights into the potential role of polycalin and ABCC2 proteins in Cry1Ac resistance and the mechanism underlying the resistance of insects to Bt toxins. [ABSTRACT FROM AUTHOR]

Trapezoidal roadways in large inclination coal seams show asymmetrical tectonic characteristics, while there is still a lack of theoretical results on stress, deformation, and efficient and effective supporting methods on high walls. In this paper, based on the geological characteristics of a large, inclined coal seam roadway, a mechanical model for stress–deformation analysis of trapezoidal section roadway was established. Complex analysis and a comfort map were employed to investigate the stress and deformation distribution on the roadway surface, and a novel yielding prop with high load capacity and constant working resistance was employed to support a high wall side based on analytical results. The results are as follows: (1) The deformation of the high wall is larger than that of the low wall, and the deformation of the roof is larger than that of the floor. The overall deformation of the surrounding rock shows that the rib closure is larger than the roof-to-floor closure. (2) The stress of the surrounding rock shows that both horizontal and vertical stresses are highest in the upper corner, indicating that the broken zone is most likely to occur at this location. (3) A new support employed with a high-yielding prop and a high-strength cable in a large, inclined angle roadway is proposed. On-site experiments were conducted in a large 5-1081 roadway of a coal mine in Shanxi, China. Under the influence of mining disturbance, the deformations at the top corner decreased by 40% compared with before. The test results show that the new support scheme can effectively control the development of roadway deformation and damage during the mining process. The new support also shows friendly environmental support and fast installation. [ABSTRACT FROM AUTHOR]

The CRISPR/Cas9 system is an efficient tool for reverse genetics validation, and the application of this system in the cell lines provides a new perspective on target gene analysis for the development of biotechnology tools. However, in the cell lines of diamondback moth, Plutella xylostella, the integrity of the CRISPR/Cas9 system and the utilization of this cell lines still need to be improved to ensure the application of the system. Here, we stabilize the transfection efficiency of the P. xylostella cell lines at different passages at about 60% by trying different transfection reagents and adjusting the transfection method. For Cas9 expression in the CRIPSPR/Cas9 system, we identified a strong endogenous promoter: the 217–2 promoter. The dual-luciferase and EGFP reporter assay demonstrated that it has a driving efficiency close to that of the IE1 promoter. We constructed pB-Cas9-Neo plasmid and pU6-sgRNA plasmid for CRISPR/Cas9 system and subsequent cell screening. The feasibility of the CRISPR/Cas9 system in P. xylostella cell lines was verified by knocking out endogenous and exogenous genes. Finally, we generated a transgenic Cas9 cell line of P. xylostella that would benefit future exploitation, such as knock-in and multi-threaded editing. Our works provides the validity of the CRISPR/Cas9 system in the P. xylostella cell lines and lays the foundation for further genetic and molecular studies on insects, particularly favoring gene function analysis. [ABSTRACT FROM AUTHOR]