Search

Porosity is a key parameter that affects the heat and moisture transfer within a grain pile. In order to investigate the distribution law of porosity in bulk grain piles in grain silos, grain compression experiment was carried out to obtain the porosity of different grain types under different moisture content and vertical pressure conditions. A porosity prediction model for grain cell based on GWO-BP neural network was proposed, and the model was compared with the porosity prediction results of BP neural network model and random forest model. Finally, the generalization ability of the model was verified using the grain cell box test. The results showed that the porosity prediction performance of the GWO-BP neural network model was the best, and the evaluation indexes of the model, including R2 of 0.960 5, RMSE of 0.013 7 and MAE of 0.013 1, were all within the permissible range. This study has provided a neural network prediction method for the determination of grain porosity, which could provide an important foundation for in-depth multi-field coupling analysis of grain piles and theoretical support for safe grain storage.

Objective: In order to solve the quality problems of YB517 transparent packaging machine, such as folds and unevenness of transparent paper on the sides of cigarette packages, a new cigarette-packaging side seal and shaping device was developed. Methods: After the improvements, the drive shaft of cigarette receiving plate of output turntable of YB517 was used as a power source, and the heating and shaping of cigarette package side seals were achieved by designing reciprocating mechanisms, heater components, cigarette package positioning components, and optimizing push seats; and using Solidworks software to simulate and analyze the displacement, velocity and acceleration of the shaping device. At the same time, it was connected to the temperature measurement and control system of "Heat sealer for Drawstring" so that the temperature parameters can be displayed and adjusted on the IPC control surface. Finally, the method of sampling in the test was used to compare and analyze the wrinkle of boxed transparent paper before and after the transformation. Results: The side seal shaping device had the advantages of no interference, gentle velocity and acceleration curve, no obvious impact and stable operation. The wrinkle ratio of boxed transparent paper decreased from 11.58% to 2.50%, which decreased 78.40%. Conclusion: It ensures product quality and improves consumers satisfaction.

ObjectiveTo evaluate the effects of different pretreatment methods and preservation time on RNA quality of peripheral blood samples, and to optimize the preservation method of peripheral blood samples.MethodsEight pretreatment methods were used to preprocess the peripheral blood from 3 healthy unrelated individuals and the treated samples were stored at -80 ℃. Total RNA of samples was extracted using Quick-RNATM Miniprep Plus kit. DNA/RNA ShieldTM was added to peripheral blood and total RNA was extracted after preservation at -80 ℃ for 0, 5, 10, 15, 30 and 60 days, respectively. The concentration, purity and integrity of RNA were determined. Statistical analyses were performed by SPSS 22.0 software to compare the differences in RNA yield, purity and integrity among the eight pretreatment methods.ResultsIn terms of purity, leukocyte pretreated with RNAlaterTM and directly cryopreservation peripheral blood showed the worst purity. The other six methods showed better purity. In terms of yield, blood cells with DNA/RNA ShieldTM came out with the highest yield, followed by peripheral blood with DNA/RNA ShieldTM. In terms of integrity, peripheral blood preserved in PAXgene Blood RNA tube method had the best integrity. Except for peripheral blood pretreated with DNA/RNA ShieldTM and blood cells pretreated with DNA/RNA shieldTM, the other five methods had statistical differences when compared to the method by keeping peripheral blood in PAXgene Blood RNA tube. The purity of RNA stored at six-time gradients ranged from 1.815 to 1.952. With the increase of storage time, RNA yield decreased from 4.516 ng to 1.039 ng, and RNA integrity decreased from 8.533 to 7.150.ConclusionAccording to the results of total RNA’s yield, purity and integrity, peripheral blood pretreated with DNA/RNA ShieldTM was the best pretreatment method. After the pretreatment, samples can be preserved for up to 60 days in low temperature.

Cylindrical vector beams (CVBs) with unique spatial polarization states have attracted great interest in recent years. However, the generation of high-power CVBs faces a significant challenge due to the limited output power of a single laser. Here, we capitalize on the brightness enhancement offered by coherent beam combining (CBC) technique and propose an architecture for generating arbitrary CVBs based on a CBC system. The phase noise is effectively compensated using an all-fiber internal phase-locking technique. By designing the polarization direction of each beamlet in the laser array, the desired mode of CVB can be generated. This work could provide a reference for generating high-power CVBs. [ABSTRACT FROM AUTHOR]

Magnesium matrix composites are essential lightweight metal matrix composites, following aluminum matrix composites, with outstanding application prospects in automotive, aerospace lightweight and biomedical materials because of their high specific strength, low density and specific stiffness, good casting performance and rich resources. However, the inherent low plasticity and poor fatigue resistance of magnesium hamper its further application to a certain extent. Many researchers have tried many strengthening methods to improve the properties of magnesium alloys, while the relationship between wear resistance and plasticity still needs to be further improved. The nanoparticles added exhibit a good strengthening effect, especially the ceramic nanoparticles. Nanoparticle-reinforced magnesium matrix composites not only exhibit a high impact toughness, but also maintain the high strength and wear resistance of ceramic materials, effectively balancing the restriction between the strength and toughness. Therefore, this work aims to provide a review of the state of the art of research on the matrix, reinforcement, design, properties and potential applications of nano-reinforced phase-reinforced magnesium matrix composites (especially ceramic nanoparticle-reinforced ones). The conventional and potential matrices for the fabrication of magnesium matrix composites are introduced. The classification and influence of ceramic reinforcements are assessed, and the factors influencing interface bonding strength between reinforcements and matrix, regulation and design, performance and application are analyzed. Finally, the scope of future research in this field is discussed. [ABSTRACT FROM AUTHOR]

We introduce a more flexible optogenetics-based mapping system attached on a stereo microscope, which offers automatic light stimulation to individual regions of interest in the cortex that expresses light-activated channelrhodopsin-2 in vivo. Combining simultaneous recording of electromyography from specific forelimb muscles, we demonstrate that this system offers much better efficiency and precision in mapping distinct domains for controlling limb muscles in the mouse motor cortex. Furthermore, the compact and modular design of the system also yields a simple and flexible implementation to different commercial stereo microscopes, and thus could be widely used among laboratories.

Recently, researches on copy number variation （CNV） have extended to every field, such as etiological exploration and precise treatment of complex diseases, as well as genetic breeding and evolution. The unique genetic characteristics of CNV have made people gradually believe that it could be used as a biological genetic marker to solve related problems. With the development of detection technology, application of CNV in forensic medicine will increase gradually. In this paper, the concept and development of CNV, as well as its application in forensic medicine are summarized, to provide new ideas for the practical application of CNV in the future.

The research on improving the photocatalytic activity of polyoxometalates (POMs) has attracted considerable attention. In this work, a functionalized calix[4]-resorcinarene ligand with four terpyridine groups (TPYR4A) was rationally designed, and then a POM-calix[4]-resorcinarene based inorganic–organic complex [Cu4Cl4(TPYR4A)]2[PWVI10WV2O40]-[PWVI12O40]·6DMA·8H2O (DMA= N,N′-dimethylacetamide) (1) was achieved by a self-assembly process. Strikingly, POM clusters were successfully encapsulated in noncovalent dimeric calix[4]-resorcinarene-copper-(II) based nanocapsules with a size of 3 nm. Markedly, 1 features a visible light absorption response with an optical band gap of 2.3 eV. More importantly, 1 exhibits obviously enhanced photocatalytic activity for oxidation of benzaldehyde upon simulated solar light excitation. Particularly, the photocatalytic performance of 1 is better than that of pure H3PW12O40 or a mixture of TPYR4A and H3PW12O40. This work offers a feasible strategy for designing POM-based hybrid materials with enhanced photocatalytic activity. [ABSTRACT FROM AUTHOR]