Dielectric barrier discharge-based defect engineering method to assist flash sintering

Oxygen vacancy OV plays an important role in a flash sintering (FS) process. In defect engineering, the methods of creating oxygen vacancy defects include doping, heating, and etching, and all of them often have complex processes or equipment. In this study, we used dielectric barrier discharge (DBD) as a new defect engineering technology to increase oxygen vacancy concentrations of green billets with different ceramics (ZnO, TiO2, and 3 mol% yttria-stabilized zirconia (3YSZ)). With an alternating current (AC) power supply of 10 kHz, low-temperature plasma was generated, and a specimen could be treated in different atmospheres. The effect of the DBD treatment was influenced by atmosphere, treatment time, and voltage amplitude of the power supply. After the DBD treatment, the oxygen vacancy defect concentration in ZnO samples increased significantly, and a resistance test showed that conductivity of the samples increased by 2–3 orders of magnitude. Moreover, the onset electric field (E) of ZnO FS decreased from 5.17 to 0.86 kV/cm at room temperature (RT); while in the whole FS, the max power dissipation decreased from 563.17 to 27.94 W. The defect concentration and conductivity of the green billets for TiO2 and 3YSZ were also changed by the DBD, and then the FS process was modified. It is a new technology to treat the green billet of ceramics in very short time, applicable to other ceramics, and beneficial to regulate the FS process

The Double Burdens of Mental Health Among AIDS Patients With Fully Successful Immune Restoration: A Cross-Sectional Study of Anxiety and Depression in China

Background: Anxiety and depression continue to be significant comorbidities for people with HIV infection. We investigated the prevalence of and factors associated with anxiety and depression among adult HIV-infected patients across China.Methods: In this cross-sectional study, we described clinical and psychosocial variables related to depression and anxiety in 4103 HIV-infected persons. Doctors assessed anxiety and depression by asking patients whether they had experienced anxiety or depression in the prior month. Patients also self-administered the Hospital Anxiety and Depression (HAD) scale; those with score ≥8 on HAD-A/D were considered to be at high risk of anxiety or depression.Results: Associations between socio-demographic, psychosocial, and ART-related clinical factors and risk of depression or anxiety were investigated using multivariable logistic regression. Among patients assessed between 9/2014 and 11/2015, 27.4% had symptoms of anxiety, 32.9% had symptoms of depression, and 19.0% had both. Recentness of HIV diagnoses (P = 0.046) was associated with elevated odds of anxiety. Older age (P = 0.004), higher educational attainment (P < 0.001), employment (P = 0.001), support from family / friends (P < 0.001), and sleep disturbance (P < 0.001), and number of ART regimen switches (P = 0.046) were associated with risk of depression, while neither sex nor transmission route showed any associations. There were no significant associations with HIV-specific clinical factors including current CD4+ T cell count and current viral load.Conclusions: Prevalence of symptoms of anxiety and depression is high in this cohort of treatment-experienced HIV patients. Psychological and social-demographic factors, rather than HIV disease status, were associated with risk of depression and anxiety. This finding highlights the need to deliver interventions to address the mental health issues affecting HIV-infected persons with fully successful immune restoration across China

Citizen experiences of smart learning in China’s cities

Abstract Citizen learning experiences can be understood as their perceptions, responses, and performances to learning resources, learning approaches, in different fields in the city. This study aimed to analyze the characteristics of citizen learning experiences of smart learning in cities, as well as the influencing factors of citizen learning experiences. Data were collected through the telephone interview, and 13,600 individuals from 68 cities were involved. Pearson correlation analysis, crosstab analysis, and chi-square analysis were used to analyze the collected data. Findings revealed that there are strong correlations among learning engagement, learning approach, and learning achievement. However, there is a weak relationship between city’s per-capita Gross Domestic Product (GDP) and learning engagement. Also, results showed that gender and age influence citizens’ perceptions of learning experiences

Garantizar un aprendizaje a distancia efectivo durante la disrupción causada por la COVID-19 : guía para docentes

El objetivo es ayudar a los docentes a comprender cuestiones clave relacionadas con la educación a distancia en el hogar durante el cierre de las escuelas por la COVID-19, así como a diseñar y facilitar actividades de aprendizaje eficaces, con un énfasis especial en la educación desde el nivel preescolar hasta el de la enseñanza secundaria.FR

Smart learning environments for a smart city: from the perspective of lifelong and lifewide learning

Abstract In the perspective of lifelong learning, lifewide learning and learning society, learning environments have expanded from schools to a more broader space, and even to the whole city. School, family, community, workplace, and museum can be regarded as typical learning environments in a smart city. But few research about learning environments had been found on the combination of schools, families, communities and other learning situations. The purpose of this paper is to describe and analyze the characteristics of typical learning environments in smart cities, as well as the relationship of these learning environments. A mixed survey was carried out, a secondary analysis of statistical data of 68 cities was conducted, and a telephone survey with a sample of 13,600 people in 68 cities was used for data collection. It was found that there were significant differences in the development levels of five typical learning environments in smart cities, i.e., school, family, community, workplace, and museum learning environments. Some relations among the five typical learning environments were found.School had high relationship with community and museum learning environments. Family was strongly correlated with workplace and museum learning environments. Community was associated with museum, family, and school learning environments, but no significant relation existed between participation in community activities and workplace learning. As a public learning space, museum was related to all other learning environments. Further research should be taken to explore the reasons behind these correlations and their influencing factors

Evaluation of antiparallel SiC Schottky diode in SiC MOSFET phase-leg configuration of synchronous rectifier

The MOSFET synchronous rectification (SR) is widely used to reduce the conduction loss during the freewheeling period. Due to the wide band gap of silicon carbide (SiC), the intrinsic body diode of SiC MOSFET exhibits a high voltage drop. Therefore, SiC Schottky diodes (SBD) and SiC MOSFETs are usually used in reverse parallel to reduce power loss. However, the increase of equivalent junction capacitance due to the addition of an external SiC SBD could bring larger turn-on current on opposite power transistor of the phase-leg. Furthermore, as the parasitic inductance associated with layout hinders the prompt transfer of current between SiC SBD and body diode, the external SiC SBD cannot be fully utilized, and it may deteriorate the overall performance, especially at heavy load. We comprehensively compare power losses when SiC SBD are antiparallel or not, at different working conditions, including different layout compactness, load current and dead time. It’s hard to get the effect of loss reduction loss when add antiparallel SiC SBD due to the parasitic inductance induced by the layout. The results can provide a guidance to properly select SiC SBD in a phase-leg configuration under SR mode for freewheeling during the dead time

Design of Online-Merge-Offline (OMO) learning environments in the post-COVID-19 era: case study analysis

Due to the new health restrictions imposed by the COVID-19 pandemic, The Online merge Offline (OMO) Learning wave has emerged, providing more open and immersive learning experiences. OMO learning relies on hybrid infrastructure and open educational practices to merge online and offline (i.e., physical classrooms) learning spaces together in real-time while simultaneously seamlessly teaching students in both the physical classroom and online. A systematic design of the learning environment is therefore needed by identifying relevant areas and success factors that support the design process of the OMO Learning environment, based on conceptual, human-centered, and didactic principles. This research used a collective case study analysis technique. Specifically, four international OMO learning case studies were collected and analyzed. The findings demonstrated the significance of designing an active learning environment, selecting technology-based on representational and communication needs, and preparing spaces and teachers for OMO learning. Additionally, it is found that technology limitations are persistent in the OMO learning contexts, requiring teachers to carefully reflect on their course designs and to apply instructional strategies and workarounds to maximize learning, community building, and the student experience

Validity of food and nutrient intakes assessed by a food frequency questionnaire among Chinese adults

Abstract Background Studies regarding the validity of the food frequency questionnaire (FFQ) and the food composition table (FCT) are limited in Asian countries. We aimed to evaluate the validity of a 64-item FFQ and different methods of constructing the FFQ FCTs for assessing dietary intakes of foods and nutrients among adults in eastern China. Methods A total of 2325 participants (aged 56.2 ± 14.9 years, 51.6% female) from nine cities in Zhejiang province who completed a 64-item FFQ and 3-day 24-hour dietary recalls (24HRs) in 2015 were included. Eight FFQ FCTs were generated covering food items and specific weights estimated using professional knowledge, representative 24HRs data, or the Chinese FCT (CFCT). Energy-adjusted intakes of foods and nutrients were estimated by residual and energy density methods. Spearman correlation coefficients (SCCs) of intakes of 14 food groups and 17 nutrients between FFQ and 24HRs were calculated to evaluate the overall validity of FFQ. Results The average intakes of most food groups and nutrients assessed with FFQ were higher than those assessed using the 24HRs. For the food groups, the averaged energy-adjusted (residual method) SCC between FFQ and 24HRs was 0.27, ranging from 0.14 (starch-rich beans) to 0.49 (aquatic products). For nutrient assessment, the weighted FCT (WFCT) performs the best, and the averaged energy-adjusted (residual method) SCC was 0.26, ranging from 0.16 (iron) to 0.37 (potassium). Similar correlations with 24HRs were observed when using other FFQ FCT in the calculation of nutrient intakes. Conclusion The 64-item Chinese FFQ and the WFCT were reasonably valid to assess the dietary intakes of certain foods and nutrients among adults in eastern China

Association of Mushrooms and Algae Consumption with Mortality among Chinese Older Adults: A Prospective Cohort Study

Mushrooms and algae are important sources of dietary bioactive compounds, but their associations with mortality remain unclear. We examined the association of mushrooms and algae consumption with subsequent risk of all-cause mortality among older adults. This study included 13,156 older adults aged 65 years and above in the Chinese Longitudinal Healthy Longevity Survey (2008–2018). Consumption of mushrooms and algae at baseline and age of 60 were assessed using a simplified food frequency questionnaire (FFQ). We used Cox proportional hazards models to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs). During 74,976 person-years of follow-up, a total of 8937 death cases were documented. After adjustment for demographic, lifestyle, and other dietary factors, participants who consumed mushrooms and algae at least once per week had a lower risk of all-cause mortality than rare consumers (0–1 time per year) (HR = 0.86; 95% CI: 0.80–0.93). Compared to participants with rare intake at both age 60 and the study baseline (average age of 87), those who maintained regular consumptions over time had the lowest hazard of mortality (HR = 0.86; 95% CI: 0.76–0.98). Our findings supported the potential beneficial role of long-term consumption of mushrooms and algae in reducing all-cause mortality among older adults. Further studies are warranted to evaluate the health benefit for longevity of specific types of mushrooms and algae