Efficient and tunable photoluminescence for terbium-doped rare-earth-based Cs2NaYCl6 double perovskite.

Lead-free double perovskite materials with efficient and stable self-trapped exciton (STE) emissions show enormous potential for next-generation solid-state lighting. However, the low-emission efficiency and difficulty of spectral regulation are two major obstacles to their application. Here, all-inorganic rare-earth-based double perovskite Cs2NaYCl6 single crystals with strong blue emissions were reported as effective hosts to accommodate lanthanide ion doping. By controlling the introduction of Tb3 + ions and efficient energy transfer from the STEs to the dopants, the emission color of Cs2NaYCl6 single crystals was flexibly modulated from blue to green. The quantum yields were also significantly improved from 10% to 78.81% by optimizing the Tb3 + ion concentration. Further, stable light-emitting diode prototypes based on Cs2NaYCl6 color conversion materials were fabricated to demonstrate the practical applications of rare-earth-based double perovskite.

Double perovskite microcrystals-based white light-emitting diodes without reabsorption of multiphase phosphors.

Here, Tb3+ ions are incorporated into Cs2Ag0.6Na0.4InCl6:Bi double perovskite microcrystals via a re-crystallization method. Tb3+ ions doping not only makes the white light spectrum adjustable, but also maintains the high photoluminescence quantum yield (PLQY). The optimal value of PLQY is 95%. These are comparable to the current highest values. Noteworthy is that, intrinsic emission of Tb3+ ions is attributed to the effective energy transfer from the trapped exciton state of the double perovskite host to Tb3+ ions. Finally, mixing 30% Tb3+ alloyed Cs2Ag0.6Na0.4InCl6:Bi and Cs2NaInCl6:10%Sb phosphors, a series of double-perovskite-based white light-emitting diodes (WLEDs) are prepared. The color coordinates of the best WLEDs are (0.34, 0.32), the lumen efficiency is 42 lm/W, and the color rendering index is 94.3. It is worth mentioning here that there is no blue light loss caused by energy reabsorption between the two phosphors, because the excitation wavelengths of the two phosphors are concentrated in the ultraviolet band. This work provides a new strategy for preparing high-performance WLED.

Stable and Efficient Upconversion Single Red Emission from CsPbI3 Perovskite Quantum Dots Triggered by Upconversion Nanoparticles.

Here, composites including highly efficient inert shell-modified NaYF4:Yb/Tm@NaYF4 upconversion nanoparticles (UCNPs) and CsPbI3 perovskite quantum dots (PQDs) have been successfully synthesized by the assistance of (3-aminopropyl)triethoxysilane (APTES) as a precursor for a SiO2 matrix. UCNPs and CsPbI3 PQDs in this composite structure show excellent stability in ambient conditions. Importantly, the efficient UC emission of CsPbI3 PQDs was realized, which means that the single red emission of inert shell-modified UCNPs can be easily obtained by depending on these composite structures. Furthermore, the single red emission wavelength can be easily regulated from 705 to 625 nm by introducing appropriate proportion of Br- ions, which is very difficult to achieve for traditional UCNPs. Moreover, benefiting from the efficient downshifting (DS) red emission of CsPbI3 PQDs, the composites possess the dual-wavelength excitation characteristics. So, the excellent dual-mode anticounterfeiting application has been demonstrated. This work will provide a new idea for the development of perovskite-based multifunctional materials.

Associations of problematic smartphone use with depressive symptoms and suicidal ideation in university students before and after the COVID-19 outbreak: A meta-analysis.

BACKGROUND AND AIM: Problematic smartphone use (PSU) has been suggested to present with depressive symptoms and suicidal ideation (SI) as well as sleep disturbance, lack of social support, and emotional isolation. The aim of this systematic review and meta-analysis was to evaluate the association between PSU with depressive symptoms and SI in university students, and to determine the potential influence of the coronavirus disease 2019 (COVID-19) outbreak. METHODS: Observational studies pertinent to our research were identified through comprehensive searches of the PubMed, Embase, Cochrane Library, and Web of Science databases. To account for potential heterogeneity, the random-effects models were employed to aggregate the findings. RESULTS: Eighteen datasets from 17 case-control studies, including 24,019 university students, were included. Among them, 8,775 (36.5 %) had PSU. A higher prevalence of depressive symptoms (odds ratio [OR]: 2.40, 95 % confidence interval [CI]: 2.19 to 2.63, p < 0.001; prediction interval: 1.95 to 2.96) was observed in university students with higher scores for PSU measures. A subgroup analysis showed a stronger association between PSU and depressive symptoms after the COVID-19 outbreak as compared to that before the outbreak (OR: 2.76 versus 2.16, p for subgroup difference = 0.002), which explained the heterogeneity. The association between PSU and depressive symptoms in university students was similar to those reported in studies from China and other countries, and in studies with different quality scores. Finally, a meta-analysis of three studies suggested that PSU was also associated with the prevalence of SI (OR: 2.18, 95 % CI: 1.77 to 2.68, p < 0.001; I2 = 0 %). CONCLUSION: In university students, PSU may be a risk factor for depressive symptoms and SI, and the association between PSU and depressive symptoms became stronger after the COVID-19 outbreak.

Ultrasensitive Detection of Dimethylamine Gas for Early Diagnosis of Parkinson's Disease Using CeO2-Coated Ti3C2Tx MXene/Carbon Nanofibers.

Parkinson's disease is a prevalent neurological disorder, with dimethylamine (DMA) recognized as a crucial breath biomarker, particularly at the parts per billion (ppb) level. Detecting DMA gas at this level, especially at room temperature and high humidity, remains a formidable challenge. This study presents an ultrasensitive chemiresistor DMA gas sensor, leveraging the CeO2-coated Ti3C2Tx MXene/carbon nanofiber (CeO2/MXene/C NFs) heterostructure to enhance dimethylamine sensing. The high conductivity of MXene, combined with C-Ti-O bonds and a sp2 hybridized hexagonal carbon structure, increases surface active sites. The presence of Ce3+ promotes the formation of surface-active oxygen species, while the MXene-CeO2 heterojunction broadens the electron depletion layer. Theoretical calculations reveal that the highest adsorption energy for DMA gas is at the Ce top site, explaining the sensor's satisfactory sensitivity, rapid response and recovery process, low detection limit (5 ppb), and high selectivity at room temperature. The Ce3+/Ce4+ dynamic self-refresh mechanism, involving surface hydroxyl elimination, enhances the sensor's performance under high-humid conditions. Clinical breath tests demonstrate the sensor's ability to distinguish between healthy individuals and Parkinson's disease patients, paving the way for developing next-generation sensors for early diagnosis of neurological disorders.

Advancements in defect engineering of two-dimensional nanomaterial-based membranes for enhanced gas separation.

The advent of two-dimensional nanomaterials, a revolutionary class of materials, is marked by their atomic-scale thickness, superior aspect ratios, robust mechanical attributes, and exceptional chemical stability. These materials, producible on a large scale, are emerging as the forefront candidates in the domain of membrane-based gas separation. The concept of defect engineering in 2D nanomaterials has introduced a novel approach in their application for membrane separation, offering an effective technique to augment the performance of these membranes. Nonetheless, the development of customized microstructures in gas separation membranes via defect engineering remains nascent. Hence, this review is designed to serve as a comprehensive guide for the application of defect engineering in 2D nanomaterial-based membranes. It delves into the most recent developments in this field, encompassing the synthesis methodologies of defective 2D nanomaterials and the mechanisms underlying gas transport. Special emphasis is placed on the utilization of defect-engineered 2D nanomaterial-based membranes in gas capture applications. Furthermore, the paper encapsulates the burgeoning challenges and prospective advancements in this area. In essence, defect engineering emerges as a promising avenue for enhancing the efficacy of 2D nanomaterial-based membranes in gas separation, offering significant potential for advancements in membrane-based gas separation technologies.

[Analysis and Modeling of Risk Factors for Children with Intestinal Acute Graft-Versus-Host Disease after Allogeneic Hematopoietic Stem Cell Transplantation].

OBJECTIVE: To analyze factors associated with intestinal acute graft-versus-host disease (aGVHD) after allogeneic hematopoietic stem cell transplantation(allo-HSCT) in children and to develop a prediction model for intestinal aGVHD after allo-HSCT in children. METHODS: The clinical data of 62 children who underwent allo-HSCT at the Department of Hematology of the People's Hospital of Xinjiang Uygur Autonomous Region from February 2018 to September 2021 were retrospectively analyzed. Intestinal aGVHD was evaluated according to the Mount Sinai Acute GVHD International Consortium (MAGIC) grading criteria, the variables were screened by LASSO (least absolute shrinkage and selection operator) regression analysis with 10-fold cross-validation, and developed a model for predicting intestinal aGVHD after allo-HSCT in children. RESULTS: A total of 33 (53.2%) of the 62 children developed intestinal aGVHD, of which 25 were degree II and 8 were degree III-IV. The results of screening variables by 10-fold cross-validated LASSO regression showed that the significant variables included ethnic minorities (OR =7.229; 95%CI: 2.337-22.354), platelet (PLT) (OR =0.971; 95%CI: 0.932-0.993), uric acid (UA) (OR =0.971; 95%CI: 0.935-0.988), C-reactive protein (CRP) (OR =1.217; 95%CI: 1.053-1.545), and viral infection (OR =10; 95%CI: 3.021-32.668), and these variables were independently associated with intestinal aGVHD in children (all P <0.05). A prediction model was constructed based on above variables. The area under the receiver operating characteristic (ROC) curve (AUC) of the model was calculated, and the AUC value was 0.985 (0.966-1), the Brier score was 0.055. The evaluation showed that the model has a high degree of discrimination and calibration. CONCLUSION: Ethnic minorities, low PLT, low UA, high CRP, and viral infections are independently associated with intestinal aGVHD in children, and early attention should be paid to these high-risk children.

Disseminated visceral Kaposi's sarcoma after allogeneic hematopoietic stem cell transplantation: a case report.

Cases of disseminated visceral Kaposi's sarcoma (KS) after allogenic hematopoietic stem cell transplantation (HSCT) are very rare worldwide, and disseminated visceral KS is often rapidly progressive and life-threatening, especially in paediatric patients. Here, the case of a 6-year-old female patient with disseminated visceral KS after allogeneic HSCT for treating severe aplastic anaemia is presented. The authors encountered difficulties in making the diagnosis due to lack of experience, but the diagnosis was achieved relatively quickly and accurately using metagenomic next-generation sequencing. After tapering and withdrawal of immunosuppressant drugs, the patient's condition was controlled. In conclusion, although HSCT-related KS is very rare, it should be considered during differential diagnosis.

Tunable and Efficient Photoluminescence of Lanthanide-Doped Cs2NaScCl6 Double Perovskite Single Crystals toward Multifunctional Light-Emitting Diode Applications.

Lead-free halide double perovskite, as one of the promising candidates for lead halide perovskite materials, shows great potential in light-emitting diodes (LEDs), benefiting from its environmental friendliness and high chemical stability. However, the poor regulation of the emission spectra severely limits its application range. Herein, various lanthanide ions were successfully doped in Cs2NaScCl6 double perovskite single crystals (DPSCs) to yield effective and stable emissions spanning from visible to near-infrared (NIR) regions. Notably, efficient energy transfer from the host to the dopants enables tunable emissions with good chromaticity, which is rarely reported in the field of lead-free double perovskite. Moreover, density functional theory calculations reveal that the high local electron density around the [LnCl6]3- octahedron in DPSCs plays a key role in the improvement of photoluminescence quantum yields (PLQYs). The optimal PLQYs are up to 84%, which increases around 3 times over that of the undoped sample. Finally, multicolor and NIR LEDs based on Ln3+-doped Cs2NaScCl6 DPSCs were fabricated and had different application functions. Specifically, the single-composite white LED shows adjustable coordinates and correlated color temperatures, while the NIR LED shows good night vision imaging. This work provides new inspiration for the application of efficient multifunctional LEDs based on lead-free double perovskite materials.

Trajectories of Job Burnout among Bus Drivers in China: A Three-Year Follow-Up Study.

This study aimed to characterize job burnout in longitudinal trajectories among bus drivers and examine the impact of variables related to job burnout for trajectories. A longitudinal study was conducted in 12,793 bus drivers in Guangdong province, China, at 3-year follow-up assessments. Growth mixture modeling (GMM) was used to estimate latent classes of burnout trajectories and multinomial logistic regression models were applied to predict membership in the trajectory classes. In general, there was a decrease in job burnout in 3 years [slope = -0.29, 95%CI = (-0.32, -0.27)]. Among those sub-dimensions, reduced personal accomplishment accounted for the largest proportion. GMM analysis identified five trajectory groups: (1) moderate-decreased (n = 2870, 23%), (2) low-stable (n = 5062, 39%), (3) rapid-decreased (n = 141, 1%), (4) moderate-increased (n = 1504, 12%), and (5) high-stable (n = 3216, 25%). Multinomial logistic regression estimates showed that depression symptoms, anxiety symptoms, and insomnia were significant negative predictors, while daily physical exercise was a significantly positive predictor. We found an overall downward trend in bus drivers' burnout, particularly in the sub-dimension of personal accomplishment. Mentally healthier drivers and those who were usually exercising were more resilient to occupational stress and less likely to suffer burnout.

The Psychological Impact of the COVID-19 Epidemic on Guangdong College Students: The Difference Between Seeking and Not Seeking Psychological Help.

BACKGROUND: Coronavirus disease 2019 (COVID-19) has considerably psychologically impacted Chinese college students. Several types of online mental health services were widely implemented for college students during the outbreak. This study investigated the relationship between college students' mental health status and psychological help-seeking behavior to test the phases-decision-making model (PDM). METHODS: A cross-sectional survey was conducted among college students in Guangdong Province using an online platform. In total, 4,164 students were assigned to the "counseling group" or "non-counseling group" according to whether they had sought psychological help because of the COVID-19 outbreak; the groups were matched based on age, sex, and grade. Demographics, perceived mental health, and experience with seeking psychological help were recorded. Fear, depression, and trauma were assessed by the COVID-19 Fear Screening Scale, Patient Health Questionnaire, and Impact of Event Scale-6. RESULTS: The fear, depression, and trauma scores were significantly higher in the counseling group than in the non-counseling group (P s < 0.001). Fear (OR = 1.27, p < 0.001), depression (OR = 1.02, p = 0.032), trauma (OR = 1.08, p < 0.001), poor perceived mental health status (OR = 3.61, p = 0.001), and experience with seeking psychological help (OR = 7.06, p < 0.001) increased the odds of seeking psychological help. CONCLUSION: During the COVID-19 epidemic, the rate of psychological help-seeking was still low, and college students in poor psychological condition sought psychological counseling more. Fear, depression, trauma, experience with seeking psychological help, and perceived mental health can effectively predict psychological help-seeking behavior. These findings emphasized the importance of closely monitoring college students' psychological status, providing psychological intervention, and improving the probability of seeking psychological help.

COVID-19 in Guangdong: Immediate Perceptions and Psychological Impact on 304,167 College Students.

The outbreak of COVID-19 has brought unprecedented psychological pressure to people across China and more widely across the entire globe. The aim of this study was to assess the immediate perceptions of COVID-19 among college students in Guangdong Province, China, and to assess the psychological impact of the outbreak. We conducted a cross-sectional survey of college students via online questionnaires between February 13th and February 22nd, 2020. A total of 304,167 students completed the Impact of Event Scale 6 (IES-6) and other items. The results showed that 155,077 (50.9%) of the students reported stress symptoms, 1,565 (0.5%) reported poor mental health, and 9,752 (3.2%) reported poor sleep quality. Analysis indicated that the students' perceptions of COVID-19 were correlated with psychological stress, self-perceived mental health and sleep quality. Moreover, the analysis revealed that the relationship between types of perception and levels of stress symptoms varied according to the students' demographic characteristics. These findings allow us to better understand psychological stress among students and the factors influencing stress during the COVID-19 outbreak. Understanding these factors will help us to design intervention programs with the aim of alleviating stress among students and reducing the potential for developing psychological disorders.

Correlations between working memory impairment and neurometabolites of prefrontal cortex and lenticular nucleus in patients with major depressive disorder.

BACKGROUND: The mechanism of working memory (WM) impairment in MDD remains unclear. We aimed to find out the mechanism by using neuropsychological tests and proton magnetic resonance spectroscopy (1H-MRS). METHODS: 31 MDD patients and 31 healthy controls were recruited in our study. The WM performance and neurometabolite ratios of prefrontal cortex (PFC) and lenticular nucleus (LN) between two groups were evaluated and compared. And the correlations between abnormal neurometabolite ratios and WM dysfunction were computed. RESULTS: Scores of SDMT, DST(forwards), VRS and 2-back Task(accuracy rate) in MDD were lower than HCs. NAA/Cr ratios of bilateral PFC in MDD were significantly lower than HCs, while no significant differences showed in NAA/Cr ratios of LN and Cho/Cr, mI/Cr values of the bilateral PFC and LN between two groups. And for MDD patients, NAA/Cr ratios in the right PFC were positively correlated with scores of DST (Forwards). CONCLUSIONS: Our findings suggest that depressed patients may have impairments in working memory, including phonological loop, visual-spatial sketchpad, episodic buffer and central executive. And the impairment of verbal WM and WM capacity may be associated with the abnormal neurometabolites in the right PFC.