Against the backdrop of the COVID-19 outbreak, an emergency policy initiative called "Suspending Classes Without Stopping Learning" was launched by the Chinese government to continue teaching ...activities as schools across the country were closed to contain the virus. However, there is ambiguity and disagreement about what to teach, how to teach, the workload of teachers and students, the teaching environment, and the implications for education equity. Possible difficulties that the policy faces include: the weakness of the online teaching infrastructure, the inexperience of teachers (including unequal learning outcomes caused by teachers' varied experience), the information gap, the complex environment at home, and so forth. To tackle the problems, we suggest that the government needs to further promote the construction of the educational information superhighway, consider equipping teachers and students with standardized home-based teaching/learning equipment, conduct online teacher training, include the development of massive online education in the national strategic plan, and support academic research into online education, especially education to help students with online learning difficulties.
Human skin color is highly heritable and one of the most variable phenotypic traits. However, the genetic causes and environmental selective pressures underlying this phenotypic variation have ...remained largely unknown. To investigate whether the pigmentation related-genes polymorphisms are associated with the geographic environmental variables. We selected randomly 795 healthy individuals from eight ethnic groups in nine provinces in China. Six single nucleotide polymorphisms (SNPs) of SLC45A2 and TYR were genotyped using Agena MassARRAY. The Chi-square test and Spearman correlation analysis were used to compare the frequency distribution of genotypes among different ethnic groups and evaluate the relationship between SNP genetic diversity and environmental variables, respectively.
The results indicated that rs28777 and rs183671 (SLC45A2) and rs1042602 (TYR) genotype frequency distributions were significantly different between the Xinjiang-Uighur and other ethnic groups (P < 0.05). Spearman correlation analysis found that rs28777-A (r = - 0.090, P = 0.011), rs183671-G (r = - 0.105, P = 0.003), rs1042602-A (r = - 0.108, P = 0.002), rs1126809-A (r = - 0.151, P < 0.001) allele frequencies were negatively correlated with the longitude; rs183671-G (r = 0.151), rs1042602-A (r = 0.157) and rs1126809-A (r = 0.138) allele frequencies were positively associated with the latitude (P < 0.001); rs183671-G (r = 0.116, P = 0.001), rs1042602-A (r = 0.105, P = 0.003) and rs1126809-A (r = 0.070, P = 0.048) allele frequencies were positively correlated with the sunshine hours; rs183671-G (r = - 0.076, P = 0.033), rs1042602-A (r = - 0.079, P = 0.027) and rs1126809-A (r = - 0.076, P = 0.031) were negatively correlated with the annual average temperature.
Our results confirmed the idea that environmental factors have been an important selective pressure upon pigmentation related gene polymorphisms.
gene, as a tumor suppressor gene was involved in the development and progress of breast cancer (BC). However, the effect of
polymorphisms on BC has rarely been reported. In the study, we aimed to ...evaluate the relation between
variants and BC risk.
Among 563 BC patients and 552 healthy controls, ten single-nucleotide polymorphisms (SNPs) in
were genotyped by Agena MassARRAY. Odds ratios (ORs) and 95% confidence interval (CI) were calculated using logistic regression model.
Our study demonstrated that rs1907168 polymorphism (heterozygous: OR = 0.71,
= 0.017) was related to the reduced risk of BC in the overall. In stratified analyses by age, rs1907168 was associated with the decreased (heterozygous: OR = 0.53,
= 0.002) while rs78205284 (homozygote: OR = 2.83,
= 0.034) increased BC susceptibility among the population at age ≤51 years. Rs6551122 (recessive: OR = 0.51,
= 0.028) and rs12635768 (homozygote, OR = 0.36,
= 0.023) polymorphisms were related to the smaller BC tumor size (<2 cm). In addition, rs112276562 (heterozygote OR = 0.56,
= 0.002), rs6551122 (heterozygote OR = 0.63,
= 0.016), and rs73150416 (heterozygote OR = 0.57,
= 0.005) variants contributed to the lower incidence of PR-positive BC. Moreover, rs6788033 was associated with a lower expression level of Ki-67 (log-additive: OR = 0.68,
= 0.024). Furthermore, we found an association of 'GATT' haplotype with an increased risk for BC. In addition,
gene was down-regulated in BC tumor and had a poor prognosis in BC in
analysis.
Our study firstly found
SNPs contributed to the risk of BC, suggesting
variants might help to predict BC progression.
China’s rapid economic development since the reform and opening up has attracted the attention of the world, while a sharp deterioration of the environment accompanies the rapid economic development. ...Starting from the current situation of economic development and environmental pollution in Shanxi Province, the interaction between economic growth and environmental pollution in Shanxi Province is comprehensively analyzed, and the influence mechanism between the two is revealed. The EKC theoretical econometric model for the relationship between economic growth and environmental pollution in Shanxi Province is constructed and empirically analyzed by combining the multicollinearity test, correlation test, unit root test, and cointegration test to obtain the data required for this study, and at the same time, to determine the research indexes and parameters. The correlation coefficients between GDP per capita and industrial wastewater discharge per capita, industrial exhaust emissions per capita, and industrial solid waste generation per capita in Shanxi province reach more than 0.5, and the Sig values (0.001, 0.004, and 0.005) are less than 0.05, which is a significant correlation, and the R
coefficient of determination of the fit of the EKC curves of GDP and exhaust emissions is 0.8532, and the expression is
= –0.1169 + 5×10
– 1×10
–1.6×10
. This study profoundly reveals the relationship between economic growth and ecological environment and promotes Shanxi Province to achieve the goals of environmental improvement and sustainable economic development.
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•Micro-mesoporous UiO-66 was synthesized with P123 as structure-directing agent.•Micro-mesoporous UiO-66 shows 2.6 times toluene adsorption capacity of UiO-66.•Micro-mesoporous ...structure improves the mass transfer rate and adsorption capacity.•Efficient regeneration of exhausted adsorbent was achieved by heating.
In this work, micro-mesoporous UiO-66 was successfully prepared with P123 (EO20PO70EO20) as structure-directing agent by a simple solvothermal method. Adsorption/desorption kinetics of gaseous toluene over pristine UiO-66 and micro-mesoporous UiO-66 were investigated by breakthrough experiments, toluene vapor adsorption isotherm measurements and temperature programmed desorption (TPD) experiments. The interactions between toluene and UiO-66 samples were assessed through the Henry’s law constant (KH) and the isosteric adsorption heat (ΔHads). The micro-mesoporous UiO-66 crystal demonstrated 2.6 times toluene adsorption capacity of the pristine UiO-66 when the P123/Zr4+ molar ratio was 0.2. Results showed that micropore adsorption was the main adsorption process and the larger pores in micro-mesoporous UiO-66 increased molecular diffusion rate and reduced the mass transfer resistance. This result indicated that micro-mesoporous structures and defect sites had a positive effect on toluene molecules capture. The breakthrough times and the working capacities decreased with the increase of the relative humidity and adsorption temperature. A good thermal stability and reproducibility were revealed over the micro-mesoporous UiO-66 in this paper.
The continuous evolution toward semiconductor technology in the “more-than-Moore” era and rapidly increasing power density of modern electronic devices call for advanced thermal interface materials ...(TIMs). Here, we report a novel strategy to construct flexible polymer nanocomposite TIMs for advanced thermal management applications. First, aligned polyvinyl alcohol (PVA) supported and interconnected 2D boron nitride nanosheets (BNNSs) composite fiber membranes were fabricated by electrospinning. Then, the nanocomposite TIMs were constructed by rolling the PVA/BNNS composite fiber membranes to form cylinders and subsequently vacuum-assisted impregnation of polydimethylsiloxane (PDMS) into the porous cylinders. The nanocomposite TIMs not only exhibit a superhigh through-plane thermal conductivity enhancement of about 10 times at a low BNNS loading of 15.6 vol % in comparison with the pristine PDMS but also show excellent electrical insulating property (i.e., high volume electrical resistivity). The outstanding thermal management capability of the nanocomposite TIMs was practically confirmed by capturing the surface temperature variations of a working LED chip integrated with the nanocomposite TIMs.
A survey of transformers Lin, Tianyang; Wang, Yuxin; Liu, Xiangyang ...
AI open,
2022, 2022-00-00, 2022-01-01, Letnik:
3
Journal Article
Recenzirano
Odprti dostop
Transformers have achieved great success in many artificial intelligence fields, such as natural language processing, computer vision, and audio processing. Therefore, it is natural to attract lots ...of interest from academic and industry researchers. Up to the present, a great variety of Transformer variants (a.k.a. X-formers) have been proposed, however, a systematic and comprehensive literature review on these Transformer variants is still missing. In this survey, we provide a comprehensive review of various X-formers. We first briefly introduce the vanilla Transformer and then propose a new taxonomy of X-formers. Next, we introduce the various X-formers from three perspectives: architectural modification, pre-training, and applications. Finally, we outline some potential directions for future research.
Polymer-based gate dielectrics have received growing attention due to their important role in field-effect transistors (OFETs). This review article aims to present the recent progress of polymer ...dielectrics for high-performance OFET applications. We first discuss the requirements for polymer dielectrics in tailoring the overall performance of OFETs from the perspective of both bulk material properties and surface characteristics of the polymers. On this basis, we introduce the design strategies and desired processing techniques of polymer dielectrics for optimizing the charge transport and stabilizing the operation of OFETs. Then, we highlight the recent advances in polymer-based dielectrics by classifying and comparing different categories of polymeric materials as well as polymer nanocomposites, and focus is also given to elucidating the critical relationships between polymer structures, gate dielectric properties and OFET performance. Finally, a perspective of future research directions and challenges for polymer dielectrics is provided.
Per- and polyfluoroalkyl substances (PFAS) are persistent chemicals and have been detected throughout the environment. Thermal treatment is the most common remediation approach for PFAS-contaminated ...solid wastes. Although various thermal treatment techniques have demonstrated the potential to destruct PFAS, the fate of PFAS, removal efficacy, potential emissions, and the formation of incomplete combustion products during thermal treatment are little known. This study provides a critical review on the behavior of PFAS based on different types of thermal treatment technologies with various PFAS-impacted environmental medias that include water, soil, sewage sludge, pure PFAS materials, and other PFAS-containing wastes. Different extents of PFAS thermal destruction are observed across various thermal treatment techniques and operating conditions. PFAS removal and destruction efficiencies rely heavily on PFAS structures, the complex combustion chemistry, the presence or absence of oxygen, temperature, and other operational conditions. This review also covers proposed PFAS thermal destruction mechanisms. Different thermal destruction mechanisms for perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS), and other PFAS are reviewed and compared. The majority of studies about PFAS thermal destruction mechanisms were focused on a specific list of PFAS and based mostly on the pyrolysis treatment. The basic pathway for PFAS destruction during pyrolysis is hydrodefluorination, which could be largely influenced by the alkaline condition. Future field-scale research that involves the characterization of PFAS destruction products and incomplete combustion products is needed to address public concerns and better emission control.
A new porous composite nanofiber manufacturing route, combining electrospinning and foaming processes, was developed. In this process, aluminum acetylacetonate (AACA) was introduced as the foaming ...agent in nanofibers made of polyacrylonitrile (PAN)/silicon (Si) nanoparticles. PAN/Si composite nanofibers were first produced through an electrospinning process and mesopores were then generated by foaming nanofibers via AACA sublimation. After further carbonization, the obtained mesoporous carbon/silicon composite nanofiber mats were tested as the anode material for lithium ion batteries. Within this composite anode, mesopores provide needed buffering space to accommodate the large volume expansion and consequent stress induced inside silicon during lithiation. This effectively mitigates silicon pulverization issue and helps achieve higher reversible capacity and better capacity retention in later battery tests when compared with anodes made of nonporous composites nanofibers and carbon nanofibers alone.
A cost-effective manufacturing process for mesoporous carbon/Si composite nanofibers, a combination of electrospinning and sublimation-based foaming processes, is introduced. When used as the anode of LIBs, mesopores provide needed buffering space to accommodate the large volume expansion and consequent stress of silicon during lithiation to successfully achieve high reversible capacity and better capacity retention when compared with anodes made of nonporous counterparts. Display omitted
•Aluminum acetylacetonate serves as a homogeneous foaming agent to produce pores in electrospun nanofibers.•Integrate sublimation-based foaming with carbon nanofiber manufacturing process.•Foamed mesopores effectively mitigate volume expansion & stress in Si lithiation.•Porous C/Si composite anode showed higher capacity and better cycling stability.
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