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Due to the small thermal neutron absorption cross section of 11B isotope, high abundance 11BF3 is regarded as an important ion implanted gas and P-type doping source, and is mainly used in semiconductor material manufacturing process to significantly improve the anti-radiation interference ability of semiconductor devices. In order to achieve the optimal design of the high-abundance 11BF3 isotope separation process, the mechanism of chemical exchange separation of 11BF3 isotopes was analyzed firstly, and the results show that the difference of intermolecular forces is responsible for the isotope separation. Then, the relative molecular weight and saturated vapor pressure data of isotope molecules were supplemented by self-defined components, and the parameters of the extended Antoine equation were regression extended in the Aspen Plus commercial chemical process simulation software. The process model of 11BF3 isotope separation based on Aspen Plus was established. RStoic reactor module was used for complexation and cracking reaction calculation, and Radfrac strict rectification module was used for exchange process calculation. Since the separation coefficient calculated by using NRTL-RK thermodynamic method was the closest to the experimental value, NRTL-RK thermodynamic method was selected for calculation in the exchange tower. In the complex tower and the cracking tower, the gas-liquid exchange process was not considered, so NRTL thermodynamic method was used. Next, based on the two sets of experimental data, the Murfree plate efficiency was used to correct the model in Aspen Plus, and the relative errors between the two sets of simulated and experimental values are -2.69% and 0.91%, respectively. It shows that the modified model can describe the process of 11BF3 isotope separation well. Finally, according to the established mathematical model, the effects of theoretical plate number, reflux ratio and column top pressure on the 11BF3 isotopic abundance at the top of the exchange column were analyzed. The results show that the decrease of the column top pressure, the increase of the reflux ratio and the increase of the theoretical plate number are all beneficial to the 11BF3 isotopic abundance. The maximum abundance of the exchange tower reaches 99.95% when the column top pressure is atmospheric pressure, the theoretical plate number is 720 and the reflux ratio is 300. The results of this paper can provide a theoretical basis for the subsequent optimization design. Subsequently, the 11BF3 isotope separation process model established in this paper can be further used to conduct multi-objective comprehensive analysis of investment cost, operating cost and abundance.

The decision regarding the distance education method in Turkey on March 15, 2020, has completely changed the learning and teaching methodology of all university students and educators, and it has been seen that all courses have started to be given with distance education. The purpose of this research is to examine the perspectives of engineering university students towards distance education during the Covid-19 pandemic. The research consists of engineering faculty students studying at various universities in the Aegean region and Russian Federation. In the research, a scanning model was used. The data of the research were collected from 520 engineering department university studentsfrom various universities in our country, according to the convenience sampling method, and through an online questionnaire filled out by the students. Thanks to this wide participation, results have been obtained that will explain the Covid-19 process related to distance education in a good way. In general, it has been concluded that students are happy to see them in distance education model courses, so they do not fall behind in their education, and university students watch their courses mostly with the help of smart devices. [ABSTRACT FROM AUTHOR]

In most organisms, various physiological and behavioral functions are expressed rhythmically. Previous studies have shown that thermoperiod is an important factor affecting circadian clock-related genes that regulate insect locomotor activity. Bradysia odoriphaga Yang & Zhang is an underground pest that attacks more than 30 crops but is especially damaging to Chinese chives. In this study, we analyzed the adult eclosion time and period (Boper) gene expression in B. odoriphaga as affected by temperature (cycling vs constant temperature), insect stage, and tissue specific. We found that the eclosion time and expression of the Boper gene changed during the temperature cycle but not under a constant temperature. Silencing of Boper expression significantly decreased the adult eclosion rate and significantly increased adult mortality and malformation. The findings indicate that thermoperiod alters Boper expression and regulates the eclosion rhythm. [ABSTRACT FROM AUTHOR]

BiVO4, a visible-light response photocatalyst, has shown tremendous potential because of abundant raw material sources, good stability and low cost. There exist some limitations for further applicaitions due to poor capability to separate electron–hole pairs. In fact, a single-component modification strategy is barely adequate to obtain highly efficient photocatalytic performance. In this work, P substituted some of the V atoms from VO4 oxoanions, namely P was doped into the V sites in the host lattice of BiVO4 by a hydrothermal route. Meanwhile, Ag as an attractive and efficient electron-cocatalyst was selectively modified on the (010) facet of BiVO4 nanosheets via facile photo-deposition. As a result, the obtained dually modified BiVO4 sheets exhibited enhanced photocatalytic degradation property of methylene blue (MB). In detail, photocatalytic rate constant (k) was 2.285 min−1 g−1, which was 2.78 times higher than pristine BiVO4 nanosheets. Actually, P-doping favored the formation of O vacancies, led to more charge carriers, and facilitated photocatalytic reaction. On the other hand, metallic Ag loaded on (010) facet effectively transferred photogenerated electrons, which consequently helped electron–hole pairs separation. The present work may enlighten new thoughts for smart design and controllable synthesis of highly efficient photocatalytic materials. [ABSTRACT FROM AUTHOR]

BACKGROUND: Over recent decades, many efficacious insecticides have been applied for control of Bemisia tabaci, one of the most notorious insect pests worldwide. Field‐evolved insecticide resistance in B. tabaci has developed globally, but remains poorly understood in China. RESULTS: In this study, a total of 30 field samples of the whitefly Bemisia tabaci from eight provinces of China were collected in 2015 to 2018. Twenty‐four of the populations were identified as Mediterranean, 'Q' type (MED), three were Middle East‐Asia Minor 1, 'B' type (MEAM1), and three were mixtures of MED/ MEAM1. After identifying whether they belong to MED or MEAM1, the selected individuals were used in bioassays assessing insecticide resistance to abamectin, thiamethoxam, spirotetramat, cyantraniliprole, and pyriproxyfen. Our results showed that all populations in the eight regions had little or no resistance to abamectin; abamectin resistance was highest in the Hunan (Changsha) and Hubei (Wuhan) regions and was lowest in the island region of Hainan (Sanya). The resistance of B. tabaci to spirotetramat, cyantraniliprole, and pyriproxyfen increased each year. The resistance to thiamethoxam remained low because of the high LC50value for the laboratory strain. CONCLUSION: These findings suggest that a rotation system using efficacious B. tabaci insecticides with differing mode of actions ought to be implemented for sustainable control to reduce the potential of resistance development. This study provides important data to support the integrated pest management and insecticide resistance management of B. tabaci in China. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

BACKGROUND: Tomato spotted wilt orthotospovirus (TSWV), one of the most devastating viruses of ornamental plants and vegetable crops worldwide, is transmitted by the western flower thrips, Frankliniella occidentalis (Pergande), in a persistent‐propagative manner. How TSWV influences the reproduction of its vector to enhance transmission and whether infection with TSWV changes the mating behavior of F. occidentalis are not fully understood. RESULTS: TSWV‐exposed thrips had a significantly longer developmental time than non‐exposed individuals. More importantly, increased developmental time was predominantly associated with adults, a stage critical for dispersal and virus transmission. In addition, TSWV‐exposed F. occidentalis produced substantially more progeny than did non‐exposed thrips. Interestingly, most of the increase in progeny came from an increase in males, a sex with a greater dispersal and virus transmission capability. Specifically, the female/male ratio of progeny shifted from 1.3–7.0/1 to 0.6–1.1/1. As for mating behavior, copulation time was significantly longer in TSWV‐exposed thrips. Finally, females tended to re‐mate less when exposed to the virus. Resistance to re‐mating may lead to reduced sperm availability in females, which translates to a larger number of male progeny under a haplodiploid system. CONCLUSION: These combined results suggest that TSWV can influence the developmental time, mating behavior, fecundity, and offspring sex allocation of its vector F. occidentalis to facilitate virus transmission. As such, a monitoring program capable of the earlier detection of the virus in host plants and/or its insect vector, thrips, using double‐antibody sandwich enzyme‐linked immunosorbent assay (DAS‐ELISA), real time quantitative polymerase chain reaction (RT‐qPCR) or virus detection strips might be beneficial for long‐term, sustainable management. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]