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1.
Nat Commun ; 13(1): 5275, 2022 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-36071065

RESUMO

Lithium-rich disordered rocksalt cathodes display high capacities arising from redox chemistry on both transition-metal ions (TM-redox) and oxygen ions (O-redox), making them promising candidates for next-generation lithium-ion batteries. However, the atomic-scale mechanisms governing O-redox behaviour in disordered structures are not fully understood. Here we show that, at high states of charge in the disordered rocksalt Li2MnO2F, transition metal migration is necessary for the formation of molecular O2 trapped in the bulk. Density functional theory calculations reveal that O2 is thermodynamically favoured over other oxidised O species, which is confirmed by resonant inelastic X-ray scattering data showing only O2 forms. When O-redox involves irreversible Mn migration, this mechanism results in a path-dependent voltage hysteresis between charge and discharge, commensurate with the hysteresis observed electrochemically. The implications are that irreversible transition metal migration should be suppressed to reduce the voltage hysteresis that afflicts O-redox disordered rocksalt cathodes.

2.
BMJ Open ; 12(8): e061850, 2022 08 24.
Artigo em Inglês | MEDLINE | ID: mdl-36002207

RESUMO

BACKGROUND: Over the years, countries reformed their pandemic plans but still healthcare systems were unprepared to handle the COVID-19 pandemic. Throughout the COVID-19 pandemic, healthcare workers (HCWs) raised issues around shortage of personal protective equipment (PPE), inadequate occupational infection prevention and control (IPC) training, lack of guidance regarding reuse/extended use of PPE and absence of HCWs. OBJECTIVE: The objective of this scoping review was to compare national and transnational pandemic plans and COVID-19 guidelines for the inclusion of recommendations regarding pandemic-specific occupational IPC training for HCWs, as well as strategies for managing the surge in PPE needs and staffing. INCLUSION CRITERIA: From each of the six WHO defined world regions, four countries with the highest burden of COVID-19 cases (as of mid-2020) were selected and attempted to locate the relevant pandemic plans and COVID-19 guidelines. METHODS: Searches were undertaken of 1: National Guidelines Clearinghouse, 2: websites of international public healthcare agencies such as WHO, the European Centre for Disease Prevention and Control (ECDC) and, 3: in-country health departments/Ministry of Health/Department of Public Health, between June 2020 and July 2021. The data were summarised under six themes drawn from publicly available pandemic plans and COVID-19 (IPC) guidelines of WHO, ECDC and 23 countries. RESULTS: The WHO, ECDC and 14 countries reported pandemic-specific IPC training; however, only four discussed training HCWs on correct PPE use; six countries listed strategies to manage the surge in demand of HCWs, while only five discussed managing the shortage of PPE. None of the COVID-19 guidelines recommended training HCWs for correct reuse or extended use of PPE and only one country's guideline outlined mandatory HCWs attendance and delivery of training in a regional language. CONCLUSION: Pandemic plans should be revised to include guiding principles regarding the delivery of pandemic specific IPC training. There is also a need to provide guidance on when countries should consider reuse and extended use of PPE. This discourse should also be reflected in disease-specific pandemic guidelines, like COVID-19 (IPC) guidelines. The aim of this review is to assist international health agencies in generating evidence-based guideline updates.


Assuntos
COVID-19 , Pandemias , COVID-19/epidemiologia , COVID-19/prevenção & controle , Pessoal de Saúde , Humanos , Controle de Infecções , Pandemias/prevenção & controle , Equipamento de Proteção Individual , SARS-CoV-2
3.
Nat Mater ; 21(9): 1066-1073, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35902748

RESUMO

Solid-state ionic conduction is a key enabler of electrochemical energy storage and conversion. The mechanistic connections between material processing, defect chemistry, transport dynamics and practical performance are of considerable importance but remain incomplete. Here, inspired by studies of fluids and biophysical systems, we re-examine anomalous diffusion in the iconic two-dimensional fast-ion conductors, the ß- and ß″-aluminas. Using large-scale simulations, we reproduce the frequency dependence of alternating-current ionic conductivity data. We show how the distribution of charge-compensating defects, modulated by processing, drives static and dynamic disorder and leads to persistent subdiffusive ion transport at macroscopic timescales. We deconvolute the effects of repulsions between mobile ions, the attraction between the mobile ions and charge-compensating defects, and geometric crowding on ionic conductivity. Finally, our characterization of memory effects in transport connects atomistic defect chemistry to macroscopic performance with minimal assumptions and enables mechanism-driven 'atoms-to-device' optimization of fast-ion conductors.


Assuntos
Eletrólitos , Difusão , Condutividade Elétrica , Eletrólitos/química , Transporte de Íons , Íons/química
4.
ACS Mater Lett ; 4(2): 424-431, 2022 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-35572738

RESUMO

The discovery of the lithium superionic conductor Li10GeP2S12 (LGPS) has led to significant research activity on solid electrolytes for high-performance solid-state batteries. Despite LGPS exhibiting a remarkably high room-temperature Li-ion conductivity, comparable to that of the liquid electrolytes used in current Li-ion batteries, nanoscale effects in this material have not been fully explored. Here, we predict that nanosizing of LGPS can be used to further enhance its Li-ion conductivity. By utilizing state-of-the-art nanoscale modeling techniques, our results reveal significant nanosizing effects with the Li-ion conductivity of LGPS increasing with decreasing particle volume. These features are due to a fundamental change from a primarily one-dimensional Li-ion conduction mechanism to a three-dimensional mechanism and major changes in the local structure. For the smallest nanometric particle size, the Li-ion conductivity at room temperature is three times higher than that of the bulk system. These findings reveal that nanosizing LGPS and related solid electrolytes could be an effective design approach to enhance their Li-ion conductivity.

5.
J Am Chem Soc ; 144(18): 8223-8230, 2022 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-35482958

RESUMO

A recently discovered new family of 3D halide perovskites with the general formula (A)1-x(en)x(Pb)1-0.7x(X)3-0.4x (A = MA, FA; X = Br, I; MA = methylammonium, FA = formamidinium, en = ethylenediammonium) is referred to as "hollow" perovskites owing to extensive Pb and X vacancies created on incorporation of en cations in the 3D network. The "hollow" motif allows fine tuning of optical, electronic, and transport properties and bestowing good environmental stability proportional to en loading. To shed light on the origin of the apparent stability of these materials, we performed detailed thermochemical studies, using room temperature solution calorimetry combined with density functional theory simulations on three different families of "hollow" perovskites namely en/FAPbI3, en/MAPbI3, and en/FAPbBr3. We found that the bromide perovskites are more energetically stable compared to iodide perovskites in the FA-based hollow compounds, as shown by the measured enthalpies of formation and the calculated formation energies. The least stable FAPbI3 gains stability on incorporation of the en cation, whereas FAPbBr3 becomes less stable with en loading. This behavior is attributed to the difference in the 3D cage size in the bromide and iodide perovskites. Configurational entropy, which arises from randomly distributed cation and anion vacancies, plays a significant role in stabilizing these "hollow" perovskite structures despite small differences in their formation enthalpies. With the increased vacancy defect population, we have also examined halide ion migration in the FA-based "hollow" perovskites and found that the migration energy barriers become smaller with the increasing en content.

6.
J Biochem ; 171(2): 187-199, 2022 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-34878535

RESUMO

N-Glycanase 1 (NGLY1) deficiency is a rare and complex genetic disorder. Although recent studies have shed light on the molecular underpinnings of NGLY1 deficiency, a systematic characterization of gene and protein expression changes in patient-derived cells has been lacking. Here, we performed RNA-sequencing and mass spectrometry to determine the transcriptomes and proteomes of 66 cell lines representing four different cell types derived from 14 NGLY1 deficient patients and 17 controls. Although NGLY1 protein levels were up to 9.5-fold downregulated in patients compared with parents, residual and likely non-functional NGLY1 protein was detectable in all patient-derived lymphoblastoid cell lines. Consistent with the role of NGLY1 as a regulator of the transcription factor Nrf1, we observed a cell type-independent downregulation of proteasomal genes in NGLY1 deficient cells. In contrast, genes involved in ribosome biogenesis and mRNA processing were upregulated in multiple cell types. In addition, we observed cell type-specific effects. For example, genes and proteins involved in glutathione synthesis, such as the glutamate-cysteine ligase subunits GCLC and GCLM, were downregulated specifically in lymphoblastoid cells. We provide a web application that enables access to all results generated in this study at https://apps.embl.de/ngly1browser. This resource will guide future studies of NGLY1 deficiency in directions that are most relevant to patients.


Assuntos
Defeitos Congênitos da Glicosilação , Defeitos Congênitos da Glicosilação/genética , Defeitos Congênitos da Glicosilação/metabolismo , Regulação da Expressão Gênica , Humanos , Peptídeo-N4-(N-acetil-beta-glucosaminil) Asparagina Amidase/deficiência , Peptídeo-N4-(N-acetil-beta-glucosaminil) Asparagina Amidase/genética , Peptídeo-N4-(N-acetil-beta-glucosaminil) Asparagina Amidase/metabolismo , Complexo de Endopeptidases do Proteassoma/metabolismo
7.
Nat Commun ; 12(1): 2853, 2021 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-33990560

RESUMO

Tin perovskites have emerged as promising alternatives to toxic lead perovskites in next-generation photovoltaics, but their poor environmental stability remains an obstacle towards more competitive performances. Therefore, a full understanding of their decomposition processes is needed to address these stability issues. Herein, we elucidate the degradation mechanism of 2D/3D tin perovskite films based on (PEA)0.2(FA)0.8SnI3 (where PEA is phenylethylammonium and FA is formamidinium). We show that SnI4, a product of the oxygen-induced degradation of tin perovskite, quickly evolves into iodine via the combined action of moisture and oxygen. We identify iodine as a highly aggressive species that can further oxidise the perovskite to more SnI4, establishing a cyclic degradation mechanism. Perovskite stability is then observed to strongly depend on the hole transport layer chosen as the substrate, which is exploited to tackle film degradation. These key insights will enable the future design and optimisation of stable tin-based perovskite optoelectronics.

8.
J Infect Public Health ; 14(5): 588-597, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33848888

RESUMO

BACKGROUND: Healthcare workers (HCWs) in high tuberculosis (TB) burden countries are at increased risk of TB infection due to increased exposures to TB patients and inadequate implementation of TB infection prevention and control (TB IPC) measures in health settings. While various guidelines on TB IPC exist, there is little understanding of the content of these guidelines, whether they are relevant to the context and are being appropriately implemented in low-and middle-income high TB burden countries. This study aimed to critically examine the implementation of TB IPC guidelines, along with factors impacting TB IPC implementation in health settings in seven high TB burden countries. METHODS: The WHO 2009 and national level TB IPC guidelines and the published literature from seven TB high burden countries were reviewed and relevant information extracted. Eleven key-stakeholders from the case study countries were interviewed to elucidate further facilitators and barriers impacting TB IPC guidelines implementation. RESULTS: Our study identified that all the study countries adopted the WHO 2009 guidelines with no or minimal modifications for the local context. Therefore, the subsequent translation of the TB IPC recommendations into practice has been limited and impaired in some settings. Poor infrastructure, inadequate space for isolation, lack of TB IPC training, limited supply of personal protective equipment, the discomfort of using N95 respirators, and a high number of TB patients were some of the factors impacting the implementation of TB IPC guidelines. CONCLUSION: The implementation of TB IPC guidelines in all seven countries was limited. It was affected by the diverse context where each of the countries and each of the facilities had a different health infrastructure and TB disease burdens. The findings warrant re-assessment of the current context prevailing in these high TB burden countries and subsequent revisions of national guidelines based to account for local context and evidence.


Assuntos
Tuberculose Latente , Tuberculose , Antibioticoprofilaxia , Pessoal de Saúde , Humanos , Controle de Infecções , Equipamento de Proteção Individual , Tuberculose/prevenção & controle
9.
Environ Res ; 194: 110689, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33412099

RESUMO

Lead is a potent neurotoxin that is particularly detrimental to children's cognitive development. Batteries account for at least 80% of global lead use and unsafe battery recycling is a major contributor to childhood lead poisoning. Our objectives were to assess the intensity and nature of child lead exposure at abandoned, informal used lead acid battery (ULAB) recycling sites in Kathgora, Savar, Bangladesh, as well as to assess the feasibility and effectiveness of a soil remediation effort to reduce exposure. ULAB recycling operations were abandoned in 2016 due to complaints from residents, but the lead contamination remained in the soil after operations ceased. We measured soil and blood lead levels (BLLs) among 69 children living within 200 m of the ULAB recycling site once before, and twice after (7 and 14 months after), a multi-part remediation intervention involving soil capping, household cleaning, and awareness-raising activities. Due to attrition, the sample size of children decreased from 69 to 47 children at the 7-month post-intervention assessment and further to 25 children at 14 months. We conducted non-parametric tests to assess changes in soil lead levels and BLLs. We conducted baseline surveys, as well as semi-structured interviews and observations with residents throughout the study period to characterize exposure behaviors and the community perceptions. We conducted bivariate and multivariate regression analyses of exposure characteristics to determine the strongest predictors of baseline child BLLs. Prior to remediation, median soil lead concentrations were 1400 mg/kg, with a maximum of 119,000 mg/kg and dropped to a median of 55 mg/kg after remediation (p < 0.0001). Among the 47 children with both baseline and post-intervention time 1 measurements, BLLs dropped from a median of 21.3 µg/dL to 17.0 µg/dL at 7 months (p < 0.0001). Among the 25 children with all three measurements, BLLs dropped from a median of 22.6 µg/dL to 14.8 µg/dL after 14 months (p < 0.0001). At baseline, distance from a child's residence to the nearest abandoned ULAB site was the strongest predictor of BLLs and baseline BLLs were 31% higher for children living within 50 m from the sites compared to those living further away (n = 69, p = 0.028). Women and children spent time in the contaminated site daily and relied on it for their livelihoods and for recreation. Overall, this study highlights the intensity of lead exposure associated with the ULAB recycling industry. Additionally, we document the feasibility and effectiveness of a multi-part remediation intervention at a contaminated site embedded within a residential community; substantially reducing child BLLs and soil lead concentrations.


Assuntos
Intoxicação por Chumbo , Chumbo , Bangladesh , Criança , Exposição Ambiental/análise , Feminino , Humanos , Chumbo/análise , Intoxicação por Chumbo/epidemiologia , Intoxicação por Chumbo/prevenção & controle , Fatores de Risco , Solo
10.
Chem Mater ; 33(14): 5652-5667, 2021 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-34483480

RESUMO

Solid electrolytes are crucial for next-generation solid-state batteries, and Na3PS4 is one of the most promising Na+ conductors for such applications, despite outstanding questions regarding its structural polymorphs. In this contribution, we present a detailed investigation of the evolution in structure and dynamics of Na3PS4 over a wide temperature range 30 < T < 600 °C through combined experimental-computational analysis. Although Bragg diffraction experiments indicate a second-order phase transition from the tetragonal ground state (α, P4̅21 c) to the cubic polymorph (ß, I4̅3m) above ∼250 °C, pair distribution function analysis in real space and Raman spectroscopy indicate remnants of a tetragonal character in the range 250 < T < 500 °C, which we attribute to dynamic local tetragonal distortions. The first-order phase transition to the mesophasic high-temperature polymorph (γ, Fddd) is associated with a sharp volume increase and the onset of liquid-like dynamics for sodium-cations (translational) and thiophosphate-polyanions (rotational) evident by inelastic neutron and Raman spectroscopies, as well as pair-distribution function and molecular dynamics analyses. These results shed light on the rich polymorphism of Na3PS4 and are relevant for a range host of high-performance materials deriving from the Na3PS4 structural archetype.

11.
R Soc Open Sci ; 8(9): 210684, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34527274

RESUMO

We report the effect of controlled particle size (obtained by using 80, 100, 120, 140 and 200 mesh) of the source materials on the synthesis of a well-known biomaterial, hydroxyapatite (Hap). In addition to this, we have also mapped the consequence of applied temperature (700°C, 800°C and 900°C) on the crystallographic properties and phase composition of the obtained Hap. Nevertheless, although with Hap, in each case, ß-tricalcium phosphate (ß-TCP) was registered as the secondary phase the ANOVA test revealed that the results of the crystallographic parameters are significantly different for the applied sintering temperature 700°C and 800°C (p < 0.05), while the data obtained for calcination temperature 800°C are not significantly different from that acquired at 900°C (p > 0.05). Fourier transform infrared spectrophotometer data ensured that, irrespective of mesh size and calcination temperature, the synthesized Hap samples were of carbonated apatite with B-type substitution. Interestingly, for all cases, the % of carbonate content was below the maximum limit (8%) of the CO32- ion present in bone tissue hydroxyapatite.

12.
J Am Chem Soc ; 142(52): 21799-21809, 2020 Dec 30.
Artigo em Inglês | MEDLINE | ID: mdl-33321041

RESUMO

In the search for high energy density cathodes for next-generation lithium-ion batteries, the disordered rocksalt oxyfluorides are receiving significant attention due to their high capacity and lower voltage hysteresis compared with ordered Li-rich layered compounds. However, a deep understanding of these phenomena and their redox chemistry remains incomplete. Using the archetypal oxyfluoride, Li2MnO2F, we show that the oxygen redox process in such materials involves the formation of molecular O2 trapped in the bulk structure of the charged cathode, which is reduced on discharge. The molecular O2 is trapped rigidly within vacancy clusters and exhibits minimal mobility unlike free gaseous O2, making it more characteristic of a solid-like environment. The Mn redox process occurs between octahedral Mn3+ and Mn4+ with no evidence of tetrahedral Mn5+ or Mn7+. We furthermore derive the relationship between local coordination environment and redox potential; this gives rise to the observed overlap in Mn and O redox couples and reveals that the onset potential of oxide ion oxidation is determined by the degree of ionicity around oxygen, which extends models based on linear Li-O-Li configurations. This study advances our fundamental understanding of redox mechanisms in disordered rocksalt oxyfluorides, highlighting their promise as high capacity cathodes.

13.
J Am Chem Soc ; 142(43): 18422-18436, 2020 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-33054192

RESUMO

Fast-ion conductors are critical to the development of solid-state batteries. The effects of mechanochemical synthesis that lead to increased ionic conductivity in an archetypical sodium-ion conductor Na3PS4 are not fully understood. We present here a comprehensive analysis based on diffraction (Bragg and pair distribution function), spectroscopy (impedance, Raman, NMR and INS), and ab initio simulations aimed at elucidating the synthesis-property relationships in Na3PS4. We consolidate previously reported interpretations regarding the local structure of ball-milled samples, underlining the sodium disorder and showing that a local tetragonal framework more accurately describes the structure than the originally proposed cubic one. Through variable-pressure impedance spectroscopy measurements, we report for the first time the activation volume for Na+ migration in Na3PS4, which is ∼30% higher for the ball-milled samples. Moreover, we show that the effect of ball-milling on increasing the ionic conductivity of Na3PS4 to ∼10-4 S/cm can be reproduced by applying external pressure on a sample from conventional high-temperature ceramic synthesis. We conclude that the key effects of mechanochemical synthesis on the properties of solid electrolytes can be analyzed and understood in terms of pressure, strain, and activation volume.

14.
BMC Infect Dis ; 20(1): 607, 2020 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-32807087

RESUMO

BACKGROUND: During an evolving outbreak or pandemic, non-pharmaceutical interventions (NPIs) including physical distancing, isolation, and mask use may flatten the peak in communities. However, these strategies rely on community understanding and motivation to engage to ensure appropriate compliance and impact. To support current activities for COVID-19, the objectives of this narrative review was to identify the key determinants impacting on engagement. METHODS: An integrative narrative literature review focused on NPIs. We aimed to identify published peer-reviewed articles that focused on the general community (excluding healthcare workers), NPIs (including school closure, quarantine, isolation, physical distancing and hygiene behaviours), and factors/characteristics (including social, physical, psychological, capacity, motivation, economic and demographic) that impact on engagement. RESULTS: The results revealed that there are a range of demographic, social and psychological factors underpinning engagement with quarantine, school closures, and personal protective behaviours. Aside from the factors impacting on acceptance and compliance, there are several key community concerns about their use that need to be addressed including the potential for economic consequences. CONCLUSION: It is important that we acknowledge that these strategies will have an impact on an individual and the community. By understanding the barriers, we can identify what strategies need to be adopted to motivate individuals and improve community compliance. Using a behavioural framework to plan interventions based on these key barriers, will also ensure countries implement appropriate and targeted responses.


Assuntos
Infecções por Coronavirus/epidemiologia , Infecções por Coronavirus/prevenção & controle , Higiene , Pandemias/prevenção & controle , Pneumonia Viral/epidemiologia , Pneumonia Viral/prevenção & controle , Quarentena/métodos , Isolamento Social , COVID-19 , Surtos de Doenças , Humanos , Instituições Acadêmicas
15.
J Infect Public Health ; 13(8): 1057-1060, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32241724

RESUMO

Hospital-acquired tuberculosis infection among healthcare workers is a global concern due to the increased attributable risk of tuberculosis infection among this group. To reduce healthcare workers' exposure to airborne Mycobacterium tuberculosis, various policies and guidelines have been developed and updated by the World Health Organisation (WHO) since 1999. In March 2019, the WHO published the updated tuberculosis infection control guidelines. It had previously been suggested that the existence of multiple guidelines and the changes in the contents across versions may confuse end-users and challenge the implementation. With this issue in mind, we examined the updated WHO 2019 TB infection control guidelines. The WHO 2019 updated guideline is a shorter and more focused document that includes more of the evidence from published systematic reviews for TB infection prevention and control. The guidelines focus on implementing TB infection control as an integrated infection control and prevention 'package'. However, a few key elements have been omitted or integrated with other WHO policies that were previously included in the guidelines, many of which are also still present in other international and in many national level TB infection control guidelines. In this commentary, we highlighted the inconsistencies in the different versions of the guidelines, the challenges that the high TB burden and low-income countries may face while implementing the guidelines and some factors that may be considered in the future guidelines. The arguments we made have important implications for tuberculosis infection control strategy development and implementation in low-income and high TB burden countries.


Assuntos
Guias como Assunto , Controle de Infecções , Tuberculose , Organização Mundial da Saúde , Humanos , Controle de Infecções/economia , Tuberculose Latente/epidemiologia , Tuberculose Latente/prevenção & controle , Tuberculose/epidemiologia , Tuberculose/prevenção & controle
16.
ACS Appl Mater Interfaces ; 12(13): 15328-15337, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32159945

RESUMO

Two-dimensional (2D) halide perovskites are receiving considerable attention for applications in photovoltaics, largely due to their versatile composition and superior environmental stability over three-dimensional (3D) perovskites, but show much lower power conversion efficiencies. Hence, further understanding of the structure-property relationships of these 2D materials is crucial for improving their photovoltaic performance. Here, we investigate by means of first-principles calculations the structural and electronic properties of 2D lead and tin Ruddlesden-Popper perovskites with general formula (BA)2An-1BnI3n+1, where BA is the butylammonium organic spacer, A is either methylammonium (MA) or formamidinium (FA) cations, B represents Sn or Pb atoms, and n is the number of layers (n = 1, 2, 3, and 4). We show that the band gap progressively increases as the number of layers decreases in both Sn- and Pb-based materials. Through substituting MA by FA cations, the band gap slightly opens in the Sn systems and narrows in the Pb systems. The electron and hole carriers show small effective masses, which are lower than those of the corresponding 3D perovskites, suggesting high carrier mobilities. The structural distortion associated with the orientation of the MA or FA cations in the inorganic layers is found to be the driving force for the induced Rashba spin-splitting bands in the systems with more than one layer. From band alignment diagrams, the transfer process of the charge carriers in the 2D perovskites is found to be from smaller to higher number of layers n for electrons and oppositely for holes, in excellent agreement with experimental studies. We also find that, when interfaced with 3D analogues, the 2D perovskites could function as hole transport materials.

17.
Environ Res ; 179(Pt A): 108722, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31550596

RESUMO

Adulteration is a growing food safety concern worldwide. Previous studies have implicated turmeric as a source of lead (Pb) exposure due to the addition of lead chromate (PbCrO4), a yellow pigment used to enhance brightness. We aimed to assess the practice of adding yellow pigments to turmeric and producer- consumer- and regulatory-factors affecting this practice across the supply chain in Bangladesh. We identified and visited the nine major turmeric-producing districts of Bangladesh as well as two districts with minimal turmeric production. In each district, we conducted semi-structured interviews and informal observations with individuals involved in the production, consumption, and regulation of turmeric. We explored perceptions of and preferences for turmeric quality. We collected samples of yellow pigments and turmeric from the most-frequented wholesale and retail markets. We collected samples of turmeric, pigments, dust, and soil from turmeric polishing mills to assess evidence of adulteration. Interviews were analyzed through an inductive, thematic coding process, with attention focused on perceptions of and preferences for turmeric quality. Samples were analyzed for Pb and chromium (Cr) concentrations via inductively coupled plasma mass spectrometry and x-ray fluorescence. In total, we interviewed 152 individuals from across the supply chain and collected 524 samples of turmeric, pigments, dust, and soil (Table S3, Table S4). Turmeric Pb and Cr concentrations were highest in Dhaka and Munshiganj districts, with maximum turmeric powder Pb concentrations of 1152 µg/g, compared to 690 µg/g in the 9 major turmeric-producing districts. We found evidence of PbCrO4-based yellow pigment adulteration in 7 of the 9 major turmeric-producing districts. Soil samples from polishing mills contained a maximum of 4257 µg/g Pb and yellow pigments contained 2-10% Pb by weight with an average Pb:Cr molar ratio of 1.3. Turmeric wholesalers reported that the practice of adding yellow pigments to dried turmeric root during polishing began more than 30 years ago and continues today, primarily driven by consumer preferences for colorful yellow curries. Farmers stated that merchants are able to sell otherwise poor-quality roots and increase their profits by asking polishers to adulterate with yellow pigments. Adulterating turmeric with lead chromate poses significant risks to human health and development. The results from this study indicate that PbCrO4 is being added to turmeric by polishers, who are unaware of its neurotoxic effects, in order to satisfy wholesalers who are driven by consumer demand for yellow roots. We recommend immediate intervention that engages turmeric producers and consumers to address this public health crisis and ensure a future with Pb-free turmeric.


Assuntos
Cromatos/análise , Curcuma/química , Contaminação de Alimentos/estatística & dados numéricos , Substâncias Perigosas/análise , Chumbo/análise , Bangladesh/epidemiologia , Curcumina , Monitoramento Ambiental , Humanos , Saúde Pública
18.
Environ Sci Technol ; 53(19): 11429-11436, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31525910

RESUMO

Lead (Pb) exposure is a major public health problem worldwide. Although high levels of Pb in blood in Bangladesh have been documented, the dominant Pb sources contributing to human exposure in rural Bangladesh have not been determined. Here, we first obtained blood from pregnant women from three rural Bangladeshi districts who were previously assessed by a case-control and sampling study, and we then conducted semistructured in-depth interviews to understand Pb exposure behavior and finally collected samples of the suspected Pb sources. We measured the Pb isotopic composition of both potential Pb sources and 45 blood samples in order to understand which of three sources predominate: (1) food from Pb-soldered cans, (2) turmeric, or (3) geophagous materials (clay, soil, or ash). The Pb isotope ratios of the three sources are distinct (p = 0.0001) and blood isotope ratios are most similar to turmeric. Elevated lead and chromium (Cr) concentrations in turmeric and a yellow pigment used in turmeric processing are consistent with reported consumption behavior that indicated turmeric as a primary contributor to blood Pb. The Pb isotopic composition analyses combined with a case-control and sampling approach provides evidence that turmeric adulterated with the yellow Pb-bearing pigment is the main Pb exposure source in these districts and illustrates the need to assess drivers and practices of turmeric adulteration, as well as the prevalence of adulteration across South Asia.


Assuntos
Isótopos , Solo , Ásia , Bangladesh , Monitoramento Ambiental , Feminino , Humanos , Gravidez , População Rural
19.
Nat Mater ; 18(12): 1278-1291, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31427742

RESUMO

In the critical area of sustainable energy storage, solid-state batteries have attracted considerable attention due to their potential safety, energy-density and cycle-life benefits. This Review describes recent progress in the fundamental understanding of inorganic solid electrolytes, which lie at the heart of the solid-state battery concept, by addressing key issues in the areas of multiscale ion transport, electrochemical and mechanical properties, and current processing routes. The main electrolyte-related challenges for practical solid-state devices include utilization of metal anodes, stabilization of interfaces and the maintenance of physical contact, the solutions to which hinge on gaining greater knowledge of the underlying properties of solid electrolyte materials.

20.
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