Minimization of Energy Level Mismatch of PCBM and Surface Passivation for Highly Stable Sn-Based Perovskite Solar Cells by Doping n-Type Polymer.

Developing high-performance and stable Sn-based perovskite solar cells (PSCs) is difficult due to the inherent tendency of Sn2+ oxidation and, the huge energy mismatch between perovskite and Phenyl-C61-butyric acid methyl ester (PCBM), a frequently employed electron transport layer (ETL). This study demonstrates that perovskite surface defects can be passivated and PCBM's electrical properties improved by doping n-type polymer N2200 into PCBM. The doping of PCBM with N2200 results in enhanced band alignment and improved electrical properties of PCBM. The presence of electron-donating atoms such as S, and O in N2200, effectively coordinates with free Sn2+ to prevent further oxidation. The doping of PCBM with N2200 offers a reduced conduction band offset (from 0.38 to 0.21 eV) at the interface between the ETL and perovskite. As a result, the N2200 doped PCBM-based PSCs show an enhanced open circuit voltage of 0.79 V with impressive power conversion efficiency (PCE) of 12.98% (certified PCE 11.95%). Significantly, the N2200 doped PCBM-based PSCs exhibited exceptional stability and retained above 90% of their initial PCE when subjected to continuous illumination at maximum power point tracking for 1000 h under one sun.

Effect of water, sanitation, handwashing and nutrition interventions on enteropathogens in children 14 months old: a cluster-randomized controlled trial in rural Bangladesh.

BACKGROUND: We evaluated the impact of low-cost water, sanitation, handwashing (WSH) and child nutrition interventions on enteropathogen carriage in the WASH Benefits cluster-randomized controlled trial in rural Bangladesh. METHODS: We analyzed 1411 routine fecal samples from children 14±2 months old in the WSH (n = 369), nutrition counseling plus lipid-based nutrient supplement (n = 353), nutrition plus WSH (n = 360), and control (n = 329) arms for 34 enteropathogens using quantitative PCR. Outcomes included the number of co-occurring pathogens; cumulative quantity of four stunting-associated pathogens; and prevalence and quantity of individual pathogens. Masked analysis was by intention-to-treat. RESULTS: 326 (99.1%) control children had one or more enteropathogens detected (mean 3.8±1.8). Children receiving WSH interventions had lower prevalence and quantity of individual viruses than controls (prevalence difference for norovirus: -11% [95% confidence interval [CI], -5 to -17%]; sapovirus: -9% [95%CI, -3 to -15%]; and adenovirus 40/41: -9% [95%CI, -2 to - 15%]). There was no difference in bacteria, parasites, or cumulative quantity of stunting-associated pathogens between controls and any intervention arm. CONCLUSIONS: WSH interventions were associated with fewer enteric viruses in children aged 14 months. Different strategies are needed to reduce enteric bacteria and parasites at this critical young age.

Ce-Doped SnO2 Electron Transport Layer for Minimizing Open Circuit Voltage Loss in Lead Perovskite Solar Cells.

In the planar heterostructure of perovskite-based solar cells (PSCs), tin oxide (SnO2) is a material that is often used as the electron transport layer (ETL). SnO2 ETL exhibits favorable optical and electrical properties in the PSC structures. Nevertheless, the open circuit voltage (VOC) depletion occurs in PSCs due to the defects arising from the high oxygen vacancy on the SnO2 surface and the deeper conduction band (CB) energy level of SnO2. In this research, a cerium (Ce) dopant was introduced in SnO2 (Ce-SnO2) to suppress the VOC loss of the PSCs. The CB minimum of SnO2 was shifted closer to that of the perovskite after the Ce doping. Besides, the Ce doping effectively passivated the surface defects on SnO2 as well as improved the electron transport velocity by the Ce-SnO2. These results enabled the power conversion efficiency (PCE) to increase from 21.1% (SnO2) to 23.0% (Ce-SnO2) of the PSCs (0.09 cm2 active area) with around 100 mV of improved VOC and reduced hysteresis. Also, the Ce-SnO2 ETL-based large area (1.0 cm2) PSCs delivered the highest PCE of 22.9%. Furthermore, a VOC of 1.19 V with a PCE of 23.3% was demonstrated by Ce-SnO2 ETL-based PSCs (0.09 cm2 active area) that were treated with 2-phenethylamine hydroiodide on the perovskite top surface. Notably, the unencapsulated Ce-SnO2 ETL-based PSC was able to maintain above 90% of its initial PCE for around 2000 h which was stored under room temperature condition (23-25 °C) with a relative humidity of 40-50%.

Influence of hydrometeorological risk factors on child diarrhea and enteropathogens in rural Bangladesh.

BACKGROUND: A number of studies have detected relationships between weather and diarrhea. Few have investigated associations with specific enteric pathogens. Understanding pathogen-specific relationships with weather is crucial to inform public health in low-resource settings that are especially vulnerable to climate change. OBJECTIVES: Our objectives were to identify weather and environmental risk factors associated with diarrhea and enteropathogen prevalence in young children in rural Bangladesh, a population with high diarrheal disease burden and vulnerability to weather shifts under climate change. METHODS: We matched temperature, precipitation, surface water, and humidity data to observational longitudinal data from a cluster-randomized trial that measured diarrhea and enteropathogen prevalence in children 6 months-5.5 years from 2012-2016. We fit generalized additive mixed models with cubic regression splines and restricted maximum likelihood estimation for smoothing parameters. RESULTS: Comparing weeks with 30°C versus 15°C average temperature, prevalence was 3.5% higher for diarrhea, 7.3% higher for Shiga toxin-producing Escherichia coli (STEC), 17.3% higher for enterotoxigenic E. coli (ETEC), and 8.0% higher for Cryptosporidium. Above-median weekly precipitation (median: 13mm; range: 0-396mm) was associated with 29% higher diarrhea (adjusted prevalence ratio 1.29, 95% CI 1.07, 1.55); higher Cryptosporidium, ETEC, STEC, Shigella, Campylobacter, Aeromonas, and adenovirus 40/41; and lower Giardia, sapovirus, and norovirus prevalence. Other associations were weak or null. DISCUSSION: Higher temperatures and precipitation were associated with higher prevalence of diarrhea and multiple enteropathogens; higher precipitation was associated with lower prevalence of some enteric viruses. Our findings emphasize the heterogeneity of the relationships between hydrometeorological variables and specific enteropathogens, which can be masked when looking at composite measures like all-cause diarrhea. Our results suggest that preventive interventions targeted to reduce enteropathogens just before and during the rainy season may more effectively reduce child diarrhea and enteric pathogen carriage in rural Bangladesh and in settings with similar meteorological characteristics, infrastructure, and enteropathogen transmission.

Inhibition of Sn2+ Oxidation in FASnI3 Perovskite Precursor Solution and Enhanced Stability of Perovskite Solar Cells by Reductive Additive.

Tin-based halide perovskite solar cells (Sn-PSCs) have attracted a progressive amount of attention as a potential alternative to lead-based PSCs (Pb-PSCs). Sn-perovskite films are fabricated by a solution process spin-coating technique. However, the efficiency of these devices varies significantly with the different batches of precursor solution due to the poor chemical stability of SnI2-DMSO and the oxidation of Sn2+ to Sn4+. This study investigated the origin of Sn2+ oxidation before film formation, and it was identified that the ionization of SnI2 in dimethyl sulfoxide (DMSO) causes the oxidation of free Sn2+ and I- ions. To address these issues, this study introduces the reductive additive 4-fluorophenylhydrazine hydrochloride (4F-PHCl) in the FASnI3 perovskite precursor solution. The hydrazine functional (-NH-NH2) group converted detrimental Sn4+ and I2 defects back to Sn2+ and I- in precursor solution while retaining the properties of the perovskite solution. Furthermore, the addition of 4F-PHCl in the precursor solution effectively slows the crystallization process, enhancing the crystallinity of FASnI3 perovskite films and guaranteeing the Sn2+/I- stoichiometric ratio, ultimately leading to a power conversion efficiency (PCE) of 10.86%. The hydrophobic fluorinated benzene ring in 4F-PHCl ensures moisture stability in perovskite films, allowing unencapsulated PSCs to retain over 92% of their initial PCE in an N2-filled glovebox for 130 days. Moreover, the 4F-PHCl-modified encapsulated PSCs showed superior operational stability for 420 h and maintained 95% of their initial PCE for 300 h under maximum power point tracking at 1 sun continuous illumination. This study's findings provide a promising pathway to create a controlled Sn-based perovskite precursor solution for highly reproducible and stable Pb-free Sn-PSCs.

Application of Potassium after Waterlogging Improves Quality and Productivity of Soybean Seeds.

Potassium (K) improves the stress tolerance of crop plants, which varies on the timing of K application and crop varieties. Soybean is a promising crop that can easily fit with the cropping pattern during kharif I season, when water logging occurs due to sudden rain. Therefore, an experiment was conducted to determine the effect of K management on the productivity and seed quality of soybean under normal and waterlogged conditions. The treatments comprised three factors, namely soybean genotypes (BU Soybean-1 and BU Soybean-2), waterlogging (WL) (control and WL for 4 days at the flowering stage (FS)), and K application (full dose as basal and 50% as basal +50% as top dress after termination of the flooding). The trial was laid out in a randomized complete block design with three replications. Findings revealed that BU Soybean-1 produced a higher number of pods and seeds pod-1 under control conditions with basal application of K. On the other hand, BU Soybean-2 produced taller plants and heavier grain, improving grain and straw yield under WL conditions when K was top dressed. The varieties absorbed a higher amount of nitrogen, phosphorus, and potassium under control conditions compared to WL when K was top dressed. Similarly, the seed protein content of both varieties was higher in the control condition with a top dressing of K. However, a higher percentage of seed germination was obtained from BU Soybean-2 in the control condition with a top dressing of K. Further, more electrical conductivity and more mean germination time were recorded in the case of BU Soybean-2 under WL with the basal application of K. Split application of 50% of recommended K fertilizer after the recession of flood water could be suggested for improved grain yield in flood-affected soybean growing areas.

Epidemiology of Imported Malaria in Netrokona District of Bangladesh 2013-2018: Analysis of Surveillance Data.

INTRODUCTION: Netrokona is one of the first phase malaria elimination targeted 8 districts of Bangladesh by 2021. The district constitutes only 7% of the population but contributes half of the malaria cases in that area. Most of the cases of that district are imported from Meghalaya State of India. The study was conducted to understand the epidemiology of these imported malaria cases for further strategy development to prevent both imported and introduced cases. METHODOLOGY: The study was retrospectively conducted on the malaria cases confirmed by microscopy and/or RDT by the government and/or NGO service providers between 2013 and 2018. The information of the cases was collected from the verbal "investigation" report of individual malaria confirmed cases. The respondents of the "investigation" were either the patients or their family members. Out of the 713 cases during the study period, descriptive analysis of 626 cases (based on the completeness of "investigation form") of the district was done using MS Excel version 2016. RESULTS: Proportion of imported malaria in Netrokona district increased from 60% in 2013 to 95% in 2018 which persists throughout the year with a little seasonal fluctuation. The overall contribution of these imported cases is 93% by cross-border workers by population type and 84%, 66%, and 95% by male, labour, and tribal population considering the factors of sex, occupation, and ethnicity, respectively. Population aged between 15 and 49 years contributed 82% of these imported cases. All of these cases occurred in the internationally bordering belt with Meghalaya State of India. Species-wise distribution revealed lower P. falciparum (63%) and higher mixed (28%) infection in imported cases compared to the 71% Pf and 20% mixed infection among the indigenous infections whereas P. vivax is similar in both cases. CONCLUSION: Imported malaria is an emerging issue that has a potential risk of increased local transmission which might be a challenge to malaria elimination in that area. Appropriate interventions targeting the cross-border workers are essential to prevent the introduced cases and subsequently avoid reestablishment when elimination of the disease is achieved.

Assessing informed consent practices during normal vaginal delivery and immediate postpartum care in tertiary-level hospitals of Bangladesh.

INTRODUCTION: This study was conducted to assess the informed consent practices during normal vaginal delivery (NVD) process and immediate postpartum care in the tertiary-level hospitals of Bangladesh. METHODS: A cross-sectional study was conducted at Dhaka Medical College Hospital (DMCH) and Sir Salimullah Medical College & Mitford Hospital (SSMCH) in November 2015. The study population and respondents were mothers who gave normal vaginal childbirth within the past 24 hours and received postpartum care in the study sites (N=190). The interview of every alternate mother from the patient register was conducted by researchers using a structured questionnaire. Descriptive analysis of findings was carried out using MS Excel 2013. RESULTS: The study findings revealed the complete absence of informed consent practices during NVD and postpartum care in the tertiary-level hospitals in Bangladesh. Consent (not informed consent) was taken from 95% of the mothers before proceeding with the NVD process, 50-72% of examinations (except breast examination, 0%) and 8-72% of procedures during postpartum care. Choice and preferences of mothers for taking an alternative process/examination/procedure were absent in all cases. CONCLUSIONS: The Respectful Maternity Care (RMC) Charter endorsed informed consent as one of the basic rights of child-bearing women. Absence of informed consent practices in the study sites indicates disrespect to maternity care and violation of this right. The Standard Clinical Management Protocols of Bangladesh also lacks clarification of this right. Improvement of the existing protocol, increased awareness and practices are essential to address protection of this right.