Electron injection and defect passivation for high-efficiency mesoporous perovskite solar cells.

Printable mesoscopic perovskite solar cells (p-MPSCs) do not require the added hole-transport layer needed in traditional p-n junctions but have also exhibited lower power conversion efficiencies of about 19%. We performed device simulation and carrier dynamics analysis to design a p-MPSC with mesoporous layers of semiconducting titanium dioxide, insulating zirconium dioxide, and conducting carbon infiltrated with perovskite that enabled three-dimensional injection of photoexcited electrons into titanium dioxide for collection at a transparent conductor layer. Holes underwent long-distance diffusion toward the carbon back electrode, and this carrier separation reduced recombination at the back contact. Nonradiative recombination at the bulk titanium dioxide/perovskite interface was reduced by ammonium phosphate modification. The resulting p-MPSCs achieved a power conversion efficiency of 22.2% and maintained 97% of their initial efficiency after 750 hours of maximum power point tracking at 55 ± 5°C.

The Effect of Mindfulness on Death Escape Acceptance in Young People: Emotion Regulation as a Mediator.

Few studies have examined young people's attitudes toward death escape acceptance and its relationship to mindfulness. This study addressed this issue and examined the mediating role of emotion regulation. In Study 1, 61 undergraduate students aged 19-22 years participated in a mindfulness intervention program, and the results showed that increasing young people's levels of mindfulness could improve their attitudes toward death escape acceptance. The Study 2, which recruited 440 young people aged 18-26 years to complete a cross-sectional survey, replicated the main effect and showed that young people's difficulty in emotion regulation fully mediated the coping effect of mindfulness. These findings suggest that individuals with high levels of mindfulness may have low levels of difficulty in emotion regulation and in turn promote healthy attitudes toward death escape acceptance.

Effects of Chinese heart-healthy diet on blood lipids, glucose, and estimated 10-y cardiovascular disease risk among Chinese adults: results on secondary outcomes of a randomized controlled trial.

BACKGROUND: Healthy diet is essential for cardiovascular disease risk management, but its effects among Chinese patients, whose diets differ from Western diets, remain largely unknown. METHODS: In this multicenter, patient- and outcome assessor-blind, randomized controlled feeding trial, 265 Chinese adults with baseline systolic blood pressure 130 to 159 mmHg were randomly assigned into Chinese heart-healthy (CHH) diet or usual diet for a 28-d intervention after a 7-d run-in period on usual diet. Blood lipids and glucose were measured from overnight fasting blood samples before and after the intervention. Ten-year cardiovascular disease risk was estimated using models previously developed and validated in Chinese. The changes in secondary outcomes of serum total cholesterol (TC), blood glucose, and 10-y cardiovascular disease risk over the intervention period were compared between intervention groups, adjusting for center, among participants with baseline and follow-up blood samples available. Sensitivity analyses were done with further adjustment for baseline values and covariables; missing data imputed; and among per-protocol population. RESULTS: Among 256 eligible participants (130 on CHH diet, 126 on control diet), 42% had hypercholesterolemia and 15% had diabetes at baseline. In the control group, TC and 10-y cardiovascular disease risk decreased after the intervention by 0.16 mmol/L and 0.91%, respectively, but blood glucose increased by 0.25 mmol/L. Compared with usual diet, the CHH diet lowered TC (-0.14 mmol/L, P = 0.017) and 10-y cardiovascular disease risk (-1.24%, P = 0.001) further. No effect on blood glucose was found. All sensitivity analyses confirmed the results on TC and 10-y cardiovascular disease risk, and analysis with multiple variables adjusted showed a borderline significant effect on blood glucose (-0.17 mmol/L, P = 0.051). The differences in intake of nutrients and food groups between intervention groups explained the results. CONCLUSIONS: The CHH diet reduced TC and 10-y cardiovascular disease risk and was likely to reduce blood glucose among Chinese adults with mild hypertension. Further studies with longer terms are warranted. This trial was registered at clinicaltrials.gov as NCT03882645.

Effect of fear of missing out on learning burnout in medical students: a moderated mediation.

Introduction: Learning burnout has a significant negative impact on students' academic performance and professional development, which has been exacerbated by the growing trend of problematic smartphone use, such as smartphone addiction, among young people. Recently, the literature on excessive social media use has revealed a critical role of fear of missing out. Objective The purpose of this study was to examine how fear of missing out affects smartphone addiction and its subsequent effect on learning burnout in college students. Methods: In Study 1, 352 medical students were recruited to complete a cross-sectional survey. In Study 2, 2,948 college students were recruited to complete a cross-sectional survey. Further in Study 3, 30 medical students were recruited into a mindfulness-based intervention program. Results: Study 1 preliminarily confirmed that fear of missing out was positively correlated with learning burnout. Study 2 then revealed a moderated mediation model showing that fear of missing out may increase smartphone addiction, which in turn affects their sleep quality and finally leads to learning burnout. This chain mediation model was moderated by the participants' level of mindfulness. To confirm the promoting role of mindfulness, Study 3 further confirmed that mindfulness training indeed can improve smartphone addiction and reduce learning burnout in medical students. Discussion: Theoretical and practical contributions were discussed, highlighting the effects of fear of missing out on smartphone addiction and a moderating role of mindfulness training.

F-doping-Enhanced Carrier Transport in the SnO2/Perovskite Interface for High-Performance Perovskite Solar Cells.

SnO2 is widely used as the electron transport layer (ETL) in n-i-p perovskite solar cells. However, the deep-level defects at the interface between SnO2 and the perovskite film will lead to energy loss, reducing the open-circuit voltage. Therefore, the interface optimization is essential to raise the efficiency and enhance the stability of perovskite solar cells. In this work, we introduce NH4F into the SnO2 electron transport layers, and the optimized SnO2 films reduce the interface defect density, improve the charge extraction, and reveal a better energy-level arrangement. Compared to the conventional SnO2 perovskite solar cell, the average Voc is improved by 70 mV with the champion efficiency up to 22.12%. Moreover, the unencapsulated F-doped SnO2 perovskite solar cells show better thermal stability (maintained 86.2%) and humidity stability (maintained 80.8%) after 35 days.

Effects of Cuisine-Based Chinese Heart-Healthy Diet in Lowering Blood Pressure Among Adults in China: Multicenter, Single-Blind, Randomized, Parallel Controlled Feeding Trial.

BACKGROUND: More than one-fifth of the world's population consumes Chinese cuisines regularly, but no evidence-based healthy diets fitting the Chinese food culture are available for implementation. METHODS: A multicenter, patient- and outcome assessor-blind, randomized feeding trial was conducted among 265 participants with 130 to 159 mm Hg baseline systolic blood pressure (SBP) for 4 major Chinese cuisines (Shangdong, Huaiyang, Cantonese, Szechuan). After a 7-day run-in period on a control diet matching the usual local diets, participants were randomized to continue with the control diet or the cuisine-based Chinese heart-healthy diet for another 28 days. The primary outcome was SBP, and secondary outcomes included diastolic blood pressure and food preference score. Linear regression models were used to estimate the intervention effects and adjustments for the center. The incremental cost per 1 mm Hg reduction in SBP was also calculated. RESULTS: A total of 265 participants were randomized (135 on the Chinese heart-healthy diet and 130 on the control diet), with 52% women, mean age of 56.5±9.8 years, and mean SBP and diastolic blood pressure of 139.4±8.3 and 88.1±8.0 mm Hg, respectively, at baseline. The change in SBP and diastolic blood pressure from baseline to the end of the study in the control group was -5.0 (95% CI, -6.5 to -3.5) mm Hg and -2.8 (95% CI, -3.7 to -1.9) mm Hg, respectively. The net difference of change between the 2 groups in SBP and diastolic blood pressure were -10.0 (95% CI, -12.1 to -7.9) mm Hg and -3.8 (95% CI, -5.0 to -2.5) mm Hg, respectively. The effect size did not differ among cuisines (P for interaction=0.173). The mean food preference score was 9.5 (with 10 the best preferred) at baseline, and the net change during intervention was 0.1 (95% CI, -0.1 to 0.2; P=0.558). The incremental cost-effectiveness ratio per 1 mm Hg SBP reduction was CNY 0.4 (USD 0.06) per day. No difference in the number of adverse events was found between the 2 groups (P=0.259), and none of the adverse events was associated with the intervention. CONCLUSIONS: The Chinese heart-healthy diet is effective, palatable, and cost-effective in reducing blood pressure in Chinese adults with high blood pressure, with a clinically significant effect applicable across major Chinese cuisine cultures. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT03882645.

Modeling and Balancing the Solvent Evaporation of Thermal Annealing Process for Metal Halide Perovskites and Solar Cells.

Triple-mesoscopic perovskite solar cells (PSCs) have attracted intensive attention due to the high stability, simple fabrication process, and low material cost. In this structure, the perovskite layer is hosted by a triple-mesoscopic scaffold of TiO2 /ZrO2 /carbon, and thus the crystal quality is sensitive to the thermal annealing process. Typically, the annealing process is conducted in a petri dish, for which the solvent evaporation of the perovskite precursor is slowed down, but not controllable and designable. To control the solvent evaporation, annealing chambers are first designed with different shape and vapor releasing channels. Then, physical simulations are performed by a finite element method, and it is found out that the chamber with a crowned top and releasing channels on the bottom sides can realize homogeneous distribution of the solvent vapor. To verify the simulation results, chambers are fabricated by 3D printing technique, for which the printing deviation can be as low as 100 µm. By balancing the solvent evaporation and release, the optimal solvent evaporation is achieved of the perovskite precursor in the triple-mesoscopic scaffold. This work offers a method to obtain homogeneous distribution of solvent vapor, and provides a new insight into understanding the influence of solvent evaporation during the thermal annealing process for PSCs.

Interfacial Energy Band Alignment Enables the Reduction of Potential Loss for Hole-Conductor-Free Printable Mesoscopic Perovskite Solar Cells.

Perovskite solar cells (PSCs) have achieved high efficiencies with diversified device architectures. In particular, printable mesoscopic PSC has attracted intensive research attention due to its simple fabrication process and superior stability. However, in the absence of hole conductors, the unfavorable energy band alignment between the perovskite and the carbon electrode usually leads to the reduction of device performance, especially the open-circuit voltage (VOC). Here, a p-type molecule, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), is utilized to post-treat the perovskite/carbon interface, which benefits the charge transfer and suppresses the charge recombination within the device. As a result, the post-treated device delivers a power conversion efficiency of 18.05% with an enhanced VOC of 1044 mV. This work provides a facile method for tuning the interfacial energy band alignment and improving performance of printable mesoscopic PSCs.

Investigating the iodide and bromide ion exchange in metal halide perovskite single crystals and thin films.

The anion exchange between MAPbX3 (X = I- or Br-) and MAX salts in a solution environment is investigated. We find that I- can enter MAPbBr3 single crystals (SC) in millimeter scale, while Br- can only penetrate the surface of MAPbI3 SC in a micrometer scale. Due to the lattice variation, the reaction is partially reversible.