Enabling Thin and Flexible Solid-State Composite Electrolytes by the Scalable Solution Process

All solid-state batteries (ASSBs) have the potential to deliver higher energy densities, wider operating temperature range, and improved safety compared with today's liquid-electrolyte-based batteries. However, of the various solid-state electrolyte (SSE) classes - polymers, sulfides, or oxides - none alone can deliver the combined properties of ionic conductivity, mechanical, and chemical stability needed to address scalability and commercialization challenges. While promising strategies to overcome these include the use of polymer/oxide or sulfide composites, there is still a lack of fundamental understanding between different SSE-polymer-solvent systems and its selection criteria. Here, we isolate various SSE-polymer-solvent systems and study their molecular level interactions by combining various characterization tools. With these findings, we introduce a suitable Li7P3S11SSE-SEBS polymer-xylene solvent combination that significantly reduces SSE thickness (∼50 μm). The SSE-polymer composite displays high room temperature conductivity (0.7 mS cm-1) and good stability with lithium metal by plating and stripping over 2000 h at 1.1 mAh cm-2. This study suggests the importance of understanding fundamental SSE-polymer-solvent interactions and provides a design strategy for scalable production of ASSBs

Methodological Review and Revision of the Global Hunger Index

The Global Hunger Index (GHI) is a multidimensional measure of hunger that considers three dimensions: (1) inadequate dietary energy supply, (2) child undernutrition, and (3) child mortality. The initial version of the index included the following three, equally weighted, non-standardized (i.e. unscaled) indicators that are expressed in percent: the proportion of the population that is calorie deficient (FAO's prevalence of undernourishment); the prevalence of underweight in children under five; and the under-five mortality rate. Several decisions regarding the original formulation of the GHI are reconsidered in light of recent discussions in the nutrition community and suggestions by other researchers, namely the choice of the prevalence of child underweight for the child undernutrition dimension, the use of the under-five mortality rate from all causes for the child mortality dimension, and the decision not to standardize the component indicators prior to aggregation. Based on an exploration of the literature, data availability and comparability across countries, and correlation analyses with indicators of micronutrient deficiencies, the index is revised as follows: (1) The child underweight indicator is replaced with child stunting and child wasting; (2) The weight of one third for the child undernutrition dimension is shared equally between the two new indicators; and (3) The component indicators of the index are standardized prior to aggregation, using fixed thresholds set above the maximum values observed in the data set. The under-five mortality rate from all causes is retained, because estimating under-five mortality attributable to nutritional deficiencies would be very costly and make the production of the GHI dependent on statistics about cause-specific mortality rates by country and year that are published irregularly, while the expected benefits are limited

Potential role of tenofovir vaginal gel for reduction of risk of herpes simplex virus in females

DHS TanDivisions of Infectious Diseases, St Michael's Hospital, University Health Network, and University of Toronto, Toronto, CanadaAbstract: A surprising result of the groundbreaking CAPRISA-004 trial, which demonstrated the efficacy of vaginal tenofovir 1% gel in reducing the risk of human immunodeficiency virus (HIV)-1 infection by 39% in heterosexual women, was the added benefit of this microbicide in reducing acquisition of herpes simplex virus type 2 (HSV-2) by 51%. HSV-2 is the most common cause of genital ulcer disease worldwide, and is responsible for considerable morbidity among women and neonates. The virus is further implicated in increasing the risk of both HIV acquisition and transmission, and may have additional adverse consequences in HIV-coinfected persons, making HSV-2 prevention an important clinical and public health objective. While tenofovir had not previously been widely considered to be an anti-herpes drug, in vitro activity against HSV is well documented, raising interest in potential future applications of tenofovir and its prodrugs in HSV-2 control. This article reviews the currently available data for tenofovir as an anti-herpes agent, as well as unanswered questions about delivery systems, drug formulation, rectal administration, drug resistance, and clinical applications.Keywords: tenofovir, herpes simplex virus type 2, microbicide, CAPRISA-00

Feasibility of vitamin D supplementation interventions to mitigate HIV pre-exposure prophylaxis-related bone mineral density loss: a cross-sectional survey

Shaoyuan Wang,1 Jean-Luc Kortenaar,1,2 Mark W Hull,3 Gordon Arbess,4 James RM Owen,4 Darrell HS Tan1,5,6 1Division of Infectious Diseases, St Michael’s Hospital, Toronto, ON, Canada; 2Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada; 3Department of Medicine, University of British Columbia, Vancouver, BC, Canada; 4Department of Family and Community Medicine, St. Michael’s Hospital, Toronto, ON, Canada; 5Centre for Urban Health Solutions, St. Michael’s Hospital, Toronto, ON, Canada; 6Division of Infectious Diseases, University of Toronto, Toronto, ON, Canada Background: Daily tenofovir disoproxil fumarate (TDF)/emtricitabine as HIV pre-exposure prophylaxis (PrEP) causes subclinical decreases in bone mineral density (BMD). We surveyed PrEP users to assess feasibility for a clinical trial of vitamin D supplementation to mitigate TDF-induced BMD loss. Methods: We recruited participants using or starting PrEP in Toronto and Vancouver. The primary objective was to assess the acceptability of daily or weekly vitamin D supplementation. We also assessed the acceptability of calcium supplementation, existing use of non-pharmacological bone health interventions, prevalence of osteoporosis risk factors, and bone health knowledge (Osteoporosis Knowledge Test, OKT). Results: Of 161 participants, 72.1% were current PrEP users, 18.0% were starting PrEP, and 9.9% did not indicate their PrEP status. All identified as males, 88.8% as gays, and 67.1% as Whites. Median (IQR) age was 32.0 (29.0, 40.0) years, and 62.1% reported family income ≥$60,000/year. Among those not already using the interventions, willingness to supplement with daily vitamin D, weekly vitamin D, or daily calcium was very high at 90.9%, 96.4%, and 93.0 %, respectively. Only 31.0% reported adequate dietary calcium intake, while 42.9% reported ≥1 osteoporosis risk factor (most commonly, alcohol and smoking). Overall bone health knowledge was low, as median (IQR) OKT score was 16/32. In post hoc comparisons, current PrEP users may have been more likely than new PrEP users to engage in bone loading exercise (Bone-specific Physical Activity Questionnaire score=12.5 vs 3.6, P=0.001) and have greater bone health knowledge (OKT=17 vs 14, P=0.08), but they had similar levels of current vitamin D supplementation (37.4% vs 21.4%, P=0.11), calcium supplementation (11.2% vs 13.8%, P=0.70), and adequate dietary calcium intake (32.7% vs 25.0%, P=0.43). Discussion: The high acceptability of vitamin D and calcium supplementation in this cohort suggests that enrollment into a clinical trial of such interventions to mitigate PrEP-induced BMD loss is feasible. Keywords: HIV, pre-exposure prophylaxis, vitamin D, calcium, bone and bones, bone densit

Enabling Thin and Flexible Solid-State Composite Electrolytes by the Scalable Solution Process

All solid-state batteries (ASSBs) have the potential to deliver higher energy densities, wider operating temperature range, and improved safety compared with today's liquid-electrolyte-based batteries. However, of the various solid-state electrolyte (SSE) classes - polymers, sulfides, or oxides - none alone can deliver the combined properties of ionic conductivity, mechanical, and chemical stability needed to address scalability and commercialization challenges. While promising strategies to overcome these include the use of polymer/oxide or sulfide composites, there is still a lack of fundamental understanding between different SSE-polymer-solvent systems and its selection criteria. Here, we isolate various SSE-polymer-solvent systems and study their molecular level interactions by combining various characterization tools. With these findings, we introduce a suitable Li7P3S11SSE-SEBS polymer-xylene solvent combination that significantly reduces SSE thickness (∼50 μm). The SSE-polymer composite displays high room temperature conductivity (0.7 mS cm-1) and good stability with lithium metal by plating and stripping over 2000 h at 1.1 mAh cm-2. This study suggests the importance of understanding fundamental SSE-polymer-solvent interactions and provides a design strategy for scalable production of ASSBs

Quantifying lithium loss in amorphous silicon thin-film anodes via titration-gas chromatography

Silicon with a high theoretical capacity (3,579 mAh/g) is a promising anode candidate for lithium-ion batteries. However, commercialization is still impeded by low Coulombic efficiency, caused by solid electrolyte interphase (SEI) formation and trapped lithium (Li)-silicon (Si) alloy during repeated volume change. Quantifying capacity losses from each factor is crucial to formulate rational design strategies for further improvement. In this work, titration-gas chromatography and cryogenic transmission electron microscopy are applied to characterize the evolution of trapped Li-Si alloy and SEI growth in a silicon thin-film anode. It is found that continuous growth of the SEI is the dominant factor for lithium inventory loss during cycling, with only a marginal increase in trapped Li-Si alloy. This study offers a quantitative approach to differentiate Li in the SEI from trapped Li in Li-Si alloy through a silicon thin-film anode, providing unique insights into identifying critical bottlenecks for developing Si anodes

Imaging real-time amorphization of hybrid perovskite solar cells under electrical biasing

Perovskite solar cells have drawn much attention in recent years, owing to its world-record setting photovoltaic performances. Despite its promising use in tandem applications and flexible devices, its practicality is still limited by its structural instability often arising from ion migration and defect formation. While it is generally understood that ion instability is a primary cause for degradation, there is still a lack of direct evidence of structural transformation at the atomistic scale. Such an understanding is crucial to evaluate and pin-point how such instabilities are induced relative to external perturbations such as illumination or electrical bias with time, allowing researchers to devise effective strategies to mitigate them. Here, we designed an in-situ TEM setup to enable real-time observation of amorphization in double cation mixed perovskite materials under electrical biasing at 1 V. It is found that amorphization occurs along the (001) and (002) planes, which represents the observation of in-situ facet-dependent amorphization of a perovskite crystal. To reverse the degradation, the samples were heated at 50 oC and was found to recrystallize, effectively regaining its performance losses. This work is vital toward understanding fundamental ion-migration phenomena and address instability challenges of perovskite optoelectronics

Imaging Real-Time Amorphization of Hybrid Perovskite Solar Cells under Electrical Biasing

Perovskite solar cells have drawn much attention recently owing to their world-record-setting photovoltaic performances, whereas their practicality is still limited by the structural instability that often arises from ion migration and defect formation. Despite the general understanding that ion instability is a primary cause for degradation, there is no observation of structural transformation at the atomistic scale. Such observation is crucial to understand how instabilities are induced by external perturbations such as illumination or electrical bias, allowing researchers to devise effective strategies to mitigate them. Here, we designed an in situ transmission electron microscopy setup to enable real-time observation of amorphization in perovskite materials under electrical biasing. To reverse the device performance degradation due to such structural changes, the samples were heated at 50 °C and were found to recrystallize, effectively regaining their performance losses. This work presents vital insights on understanding ion-migration phenomena and addressing instability challenges of perovskite optoelectronics