DFT Investigation of Structural Stability, Optical Properties, and PCE for All-Inorganic Csx(Pb/Sn)yXz Halide Perovskites.

Employing all-inorganic perovskites as light harvesters has recently drawn increasing attention owing to the strong-bonded inorganic components in the crystal. To achieve the systematic and comprehensive understanding for the structures and properties of Csx(Pb/Sn)yXz (X = F, Cl, Br, I) perovskites, this work provides the comparison details about crystal structures, optical properties, electronic structures and power conversion efficiency (PCE) of 18 perovskites. The suitable band gaps are detected in CsSnCl3-Pm3̅m (0.96 eV), γ-CsPbI3-Pnma (1.75 eV), and CsPbBr3-Pm3̅m (1.78 eV), facilitating the conversion from absorbing photon energy to generating hole-electron pairs. γ-CsPbI3-Pnma and CsSnI3-P4/mbm show superior visible-absorption performance depending on their higher absorption coefficient (α); meanwhile, strong peaks can be observed in the real part (Re) of photoconductivity of CsPbBr3-Pbnm, γ-CsPbI3-Pnma, and CsSnI3-P4/mbm in the visible-light range, implying their better photoelectric conversion abilities. The perovskite/tungsten disulfide (WS2) heterojunctions are constructed to calculate the PCE. Although just the PCE result (14.43%) of CsSnI3-Pnma/WS2 is reluctantly competitive, the predictions of PCEs indicate that the PCE of PSCs (perovskite solar cells) can be improved by not only regulating the perovskite to upgrade its own performance but also designing the PSC structure reasonably including the selection of appropriate ETL/HTL (electron/hole transport layer), etc.

Practical and psychological challenges faced by Wuhan graduates after COVID-19 was controlled.

Introduction: This study seeks to understand the reality and psychological difficulties faced by university graduates in Wuhan after the COVID-19 epidemic was controlled. Methods: A total of 6,417 graduate students were surveyed through an online questionnaire from late May to early June 2020. The questionnaire asked questions on depression, anxiety, insomnia, and suicidal behavior. In addition, self-administered epidemic-related questionnaires consisting of eight items were collected from university graduates. Results: Participants' positive detection rates for depression, anxiety, insomnia, and suicidal behavior are 13.4%, 8.3%, 4.4%, and 12.1%, respectively. The three biggest challenges faced by graduates are future development, economic difficulties, and employment problems. Conclusion: The detectable rate of depression, anxiety, and insomnia is low, and the detectable rate of suicide symptoms should be given more attention. The biggest problem of this group is their future development, and what they want to solve the most is the economic difficulty.

Psychological stress of university students in the hardest-hit areas at different stages of the COVID-19 epidemic.

BACKGROUND: The outbreak of COVID-19 has caused extremely many serious consequences for the country and the world. In fact, it has seriously affected people's mental health. The purpose of this study is to understand the psychological stress among college students in different stages of epidemics in hard-hit areas such as Hubei. Moreover, to highlight the factors that influencing, their psychological conditions with the emphasis of further corresponding suggestions. METHODS: This study includes self-designed questionnaires in order to assess and analyze the psychological state of over 17,000 college students during the outbreak period in January and home quarantine in February. The questionnaire contains three aspects and six dimensions: pressure responses: stress susceptibility (SS), stress adjustment (SA), risk cognition: cognition of danger (CD), cognition of illness (CI) and stress reactions: emotional responses (ER), somatic responses (SR). This survey was done by an online questionnaire (www.wjx.cn) to investigate the psychological stress information of college students, and analyzed the data by SPSS 22.0 for Windows. RESULTS: Regarding the stress susceptibility, participants were more likely stressed in February than in January. Regarding the stress adjustment, the number of participants requiring pressure regulation or release in the February survey was significantly lower than that the effective in the January survey. The mean of the cognition of danger reduced significantly in February than in January, in other words, participants were highly worried about the epidemic in January than in February. Regarding the cognition of illness, participants in January had a more pessimistic attitude towards the epidemic than those in February. The emotional responses of the participants in February were more severe than those in January, while the somatic responses reduced significantly in February compared with January. Furthermore, females have stronger stress reactions than males. However, the SR doesn't have significant differences between females and males. CONCLUSION: After two surveys in January and February, it was found that the psychological stress of college students in Hubei was significantly different at different stages of the epidemic, where the epidemic developed, the psychological stress of college students become more severe. The psychological stress of the college students in Hubei Province, as a severely affected area, should be paid more attention.

Psychological Typhoon Eye Effect During the COVID-19 Outbreak.

Background: The COVID-19 outbreak in Wuhan, Hubei, has brought serious consequences to the lives and mental health of people and has induced psychological stress and affected behavior. Methods: This study used self-designed questionnaires and SPSS to analyze the psychological and behavioral responses of people in different regions during the COVID-19 pandemic and to check for the presence of "psychological typhoon eye" (PTE) effects. The questionnaires adopted three measurement subscales, namely, the risk cognitive subscale, stress response subscale, and behavioral response subscale, and these were administered online (www.wjx.cn) to investigate the psychological and behavioral conduct of respondents from three areas that have been affected by COVID-19 to varying degrees. Exploratory factor analysis and principal component analysis were conducted to explore the factorial structure of these subscales, and confirmatory factor analysis was conducted to explore the structural validity of the questionnaires. The analysis results were used to build a revised 18-item questionnaire which validity was evaluated via ANOVA and LSD. Results: Results confirm the presence of PTE in the research areas during the onset of the COVID-19 outbreak and highlight some significant differences in the cognition and emotions of the residents in these areas. PTE affected the cognition, emotions, and cognitive and emotional responses of the respondents but did not affect their behavioral responses. Conclusion: The findings underscore the urgency of providing sustainable mental health care services across different areas during the COVID-19 outbreak. The residents of those areas worst hit by the pandemic, who may not have taken the situation seriously, require emotional guidance the most. Meanwhile, the residents of other areas, who showed the most negative psychological reactions to the pandemic, require a sense of security, a timely "disconnection" from negative information, an accurate cognition of stress, and an acceptance of self-responses.

Emotional "inflection point" in public health emergencies with the 2019 new coronavirus pneumonia (NCP) in China.

BACKGROUND: The outbreak of the new coronavirus pneumonia (NCP) in Wuhan, Hubei, has caused very serious consequences and severely affected people's lives and mental health. The outbreak will cause bad emotions such as tension, anxiety, fear, and so on. College students who have returned home from school face infection, isolation, and delay in starting school, and thus, their emotional stress should be observed. METHODS: This study used self-designed questionnaires and artificial intelligence (AI) to assess and analyze the emotional state of over 30,000 college students during the outbreak period in January (T1) and home quarantine in February (T2). This survey used online questionnaire (www.wjx.cn) to investigate the emotion information of college students. RESULTS: In the T1 survey, the "Typhoon Eye Effect" appeared. College students in Hubei are calmer than those outside Hubei in T1. However, in T2, an emotional "infection point" appeared, there was an "Exposure Effect", the negative emotions of students in Hubei largely increased and became higher than students outside Hubei. CONCLUSION: This survey found that there is an emotional "infection point" in February among college students, especially in the Hubei area. College students in Hubei are calmer than those outside Hubei in T1. In contrast, college students in Hubei were more nervous and scared than those outside Hubei in T2. This epidemic has caused the students to experience significant pressure and negative emotions. Therefore, universities and society should pay attention to their emotional adjustment, there are some suggestions such as establish the mental health organizations, test students' emotion status regularly.

Psychological stress of medical staffs during outbreak of COVID-19 and adjustment strategy.

COVID-19 has a significant impact on public health and poses a challenge to medical staffs, especially to front-line medical staffs who are exposed to and in direct contact with patients. To understand the psychological stress status of medical staffs during the outbreak of COVID-19, random sample questionnaire survey was conducted among 2110 medical staffs and 2158 college students in all provinces of China through a questionnaire, which was compiled and completed through the Questionnaire Star platform relying on Wechat, QQ, and other social software. The differences in psychological stress status of different groups were compared through the analysis of the questionnaire. Results revealed that in all provinces of China, medical staffs scored significantly higher on all items of psychological stress than college students (P < .001). In Wuhan, medical staffs scored significantly higher than college students in all items of psychological stress (P < .001). While among medical staffs, the group in Wuhan area scored significantly higher than the group outside Wuhan on the following items: "Thought of being in danger," "The possibility of self-illness," "Worrying about family infection" (P < .05), "Poor sleep quality," "Needing psychological guidance," and "Worrying about being infected" (P < .01) in the Psychological Stress Questionnaire, but on the item "Confidence in the victory of the epidemic," the group in Wuhan area scored significantly lower than the group outside Wuhan (P < .05). The emotion, cognition, physical, and mental response of front-line medical staff showed obvious "exposure effect", which calls for a psychological crisis intervention strategy that can be helpful.