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Bacterial cell wall peptidoglycan is essential, maintaining both cellular integrity and morphology, in the face of internal turgor pressure. Peptidoglycan synthesis is important, as it is targeted by cell wall antibiotics, including methicillin and vancomycin. Here, we have used the major human pathogen Staphylococcus aureus to elucidate both the cell wall dynamic processes essential for growth (life) and the bactericidal effects of cell wall antibiotics (death) based on the principle of coordinated peptidoglycan synthesis and hydrolysis. The death of S. aureus due to depletion of the essential, two-component and positive regulatory system for peptidoglycan hydrolase activity (WalKR) is prevented by addition of otherwise bactericidal cell wall antibiotics, resulting in stasis. In contrast, cell wall antibiotics kill via the activity of peptidoglycan hydrolases in the absence of concomitant synthesis. Both methicillin and vancomycin treatment lead to the appearance of perforating holes throughout the cell wall due to peptidoglycan hydrolases. Methicillin alone also results in plasmolysis and misshapen septa with the involvement of the major peptidoglycan hydrolase Atl, a process that is inhibited by vancomycin. The bactericidal effect of vancomycin involves the peptidoglycan hydrolase SagB. In the presence of cell wall antibiotics, the inhibition of peptidoglycan hydrolase activity using the inhibitor complestatin results in reduced killing, while, conversely, the deregulation of hydrolase activity via loss of wall teichoic acids increases the death rate. For S. aureus, the independent regulation of cell wall synthesis and hydrolysis can lead to cell growth, death, or stasis, with implications for the development of new control regimes for this important pathogen.
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Parede Celular/fisiologia , Peptidoglicano/metabolismo , Staphylococcus aureus/crescimento & desenvolvimento , Antibacterianos/farmacologia , Anti-Infecciosos/metabolismo , Anti-Infecciosos/farmacologia , Proteínas de Bactérias/metabolismo , Parede Celular/metabolismo , Homeostase , Meticilina/farmacologia , N-Acetil-Muramil-L-Alanina Amidase/metabolismo , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/metabolismo , Ácidos Teicoicos/metabolismo , Vancomicina/farmacologiaRESUMO
BACKGROUND: The ward round is an integral part of everyday surgical practice. It is a complex clinical activity that requires both sound clinical management and communication skills. This study reports the results of a consensus-building exercise on the common aspects of the general surgical ward rounds. METHODS: The consensus-building committee involving a range of stakeholders from 16 United Kingdom (UK) National Health Service trusts took part in this consensus exercise. The members discussed and suggested a series of statements concerning surgical ward round. An agreement of ≥ 70% among members was regarded as a consensus. RESULTS: Thirty-two members voted on 60 statements. There was a consensus on fifty-nine statements after the first round of voting, and one statement was modified before it reached consensus in the second round. The statements covered nine sections: a preparation phase, team allocation, multidisciplinary approach to the ward round, structure of the round, teaching considerations, confidentiality and privacy, documentation, post-round arrangements, and weekend round. There was a consensus on spending time to prepare for the round, a consultant-led round, involvement of the nursing staff, an MDT round at the beginning and end of the week, a minimum of 5 min allocated to each patient, utilisation of a round checklist, afternoon virtual round, and a clear handover and plan for the weekend. CONCLUSION: The consensus committee achieved agreement on several aspects concerning the surgical ward rounds in the UK NHS. This should help improve the care of surgical patients in the UK.
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Medicina Estatal , Humanos , Consenso , Técnica Delphi , Reino UnidoRESUMO
BACKGROUND: The COVID-19 pandemic has negatively impacted people living with obesity. The aim was to examine the continued impact of the COVID-19 pandemic on the mental health of people living with obesity and associations with food insecurity, loneliness and health-related behaviours. METHODS: The study recruited 1187 UK adults living with obesity who completed an online survey, which examined mental health and associations with food insecurity, loneliness and health-related behaviours from July 2020 (end of the first lockdown in the United Kingdom) to the point they completed the survey in 2021. Regression analyses were used to examine relationships between outcome variables and demographic factors, and hierarchical linear regression models were used to assess levels of loneliness, depression and well-being. RESULTS: Participants reported worse loneliness, depression, well-being and food insecurity compared to pre-COVID. However, participants reported attempting to lose weight, healthier food shopping, diet and increased physical activity. Quality and quantity of sleep deteriorated compared to prior to COVID-19. CONCLUSIONS: Adults living with obesity in the United Kingdom report a continued negative impact of the COVID-19 pandemic upon their mental health together with increased loneliness and food insecurity. However, our findings suggest that UK adults living with obesity have increased their engagement in positive health behaviours and were attempting to lose weight.
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COVID-19 , Adulto , Humanos , COVID-19/epidemiologia , Saúde Mental , Solidão , Pandemias , Controle de Doenças Transmissíveis , Obesidade/epidemiologia , Comportamentos Relacionados com a Saúde , Insegurança Alimentar , Redução de PesoRESUMO
BACKGROUND: Bariatric and Metabolic Surgery (BMS) is a popular weight loss intervention worldwide, yet few scientific studies have examined variations in preoperative practices globally. This study aimed to capture global variations in preoperative practices concerning patients planned for BMS. METHODS: A 41-item questionnaire-based survey was designed and the survey link was freely distributed on social and scientific media platforms, email groups and circulated through personal connections of authors. The survey included eight parts: basic information; criteria for BMS; preoperative nutritional screening; preoperative weight loss; preoperative diets for liver size reduction; preoperative glycemic control; other laboratory investigations and preparations; decision making, education, and consents. Descriptive statistics were used to analyse data and graphs were used for representation where applicable. RESULTS: Six hundred thirty-four bariatric healthcare professionals from 76 countries/regions completed the survey. Of these, n = 310 (48.9%) were from public hospitals, n = 466 (73.5%) were surgeons, and the rest were multidisciplinary professionals. More than half of respondents reported using local society/association guidelines in their practice (n = 310, 61.6%). The great majority of respondents routinely recommend nutritional screening preoperatively (n = 385, 77.5%), mandatory preoperative diets for liver size reduction (n = 220, 53.1%), routine screening for T2DM (n = 371, 90.7%), and mandate a glycemic control target before BMS in patients with T2DM (n = 203, 55.6%). However, less than half (n = 183, 43.9%) recommend mandatory preoperative weight loss to all patients. Most respondents (n = 296, 77.1%) recommend psychological intervention before surgery for patients diagnosed with psychological conditions. Variations were also identified in laboratory investigations and optimisation; and in the aspects of decision making, education and consent. CONCLUSIONS: This survey identified significant global variations in preoperative practices concerning patients seeking primary BMS. Our findings could facilitate future research for the determination of best practice in these areas of variations, and consensus-building to guide clinical practice while we wait for that evidence to emerge.
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Cirurgia Bariátrica , Diabetes Mellitus Tipo 2 , Obesidade Mórbida , Atenção à Saúde , Humanos , Avaliação Nutricional , Estado Nutricional , Obesidade Mórbida/cirurgia , Inquéritos e Questionários , Redução de PesoRESUMO
BACKGROUND: This is the second updated Enhanced Recovery After Surgery (ERAS®) Society guideline, presenting a consensus for optimal perioperative care in bariatric surgery and providing recommendations for each ERAS item within the ERAS® protocol. METHODS: A principal literature search was performed utilizing the Pubmed, EMBASE, Cochrane databases and ClinicalTrials.gov through December 2020, with particular attention paid to meta-analyses, randomized controlled trials and large prospective cohort studies. Selected studies were examined, reviewed and graded according to the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system. After critical appraisal of these studies, the group of authors reached consensus regarding recommendations. RESULTS: The quality of evidence for many ERAS interventions remains relatively low in a bariatric setting and evidence-based practices may need to be extrapolated from other surgeries. CONCLUSION: A comprehensive, updated evidence-based consensus was reached and is presented in this review by the ERAS® Society.
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Cirurgia Bariátrica , Recuperação Pós-Cirúrgica Melhorada , Consenso , Humanos , Assistência Perioperatória/métodos , Estudos ProspectivosRESUMO
PURPOSE OF REVIEW: Bariatric surgery is an effective treatment option for severe and complex obesity; however, those who undergo such surgery need access to nutritional monitoring and vitamin and mineral supplementation to avoid the development of nutritional deficiencies. RECENT FINDINGS: The British Obesity and Metabolic Surgery Society and the American Society for Metabolic and Bariatric Surgery have recently updated their recommendations on preoperative and postoperative nutritional monitoring and supplementation. There is a growing interest in the more malabsorptive procedures that are associated with an increased risk of nutritional deficiencies. Nutritional monitoring and prevention of nutritional deficiencies are discussed.Long-term follow-up that includes annual nutritional monitoring and access to a dietetic annual review is recommended; however, in the United Kingdom, many bariatric surgery centres are only commissioned to provide 2 years of follow-up, after which care is transferred to the general practitioner. Consideration should be given to developing shared care models for aftercare and also for the aftercare of malabsorptive procedures to remain with specialist centres. SUMMARY: Bariatric surgery is a safe and effective treatment option for severe and complex obesity. It is essential that patients have access to lifelong nutritional monitoring adjustment of vitamin and mineral supplements to prevent nutritional issues.
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Cirurgia Bariátrica , Desnutrição , Terapia Nutricional , Obesidade Mórbida , Cirurgia Bariátrica/efeitos adversos , Suplementos Nutricionais , Humanos , Desnutrição/diagnóstico , Desnutrição/etiologia , Desnutrição/prevenção & controle , Obesidade/prevenção & controle , Obesidade Mórbida/cirurgiaRESUMO
Obesity now affects 25% of the UK population. This volume of patients cannot be managed by current NHS services. It really needs a public health approach which encourages an environment where it is easier for the public to take healthy rather than unhealthy actions. However, there remain substantial numbers of patients who will benefit from medical intervention. This needs a joined-up service which extends from a healthy environment, linking gyms, weight loss groups, community cooking lessons, etc. with pathways connecting primary and secondary healthcare. To date, the National Health Service has not managed to develop a coherent policy that addresses obesity as a major cause of health and social care expenditure. The most important step in primary care is probably to identify the presence of obesity. The medical steps should be in the identification and management of comorbidities. The purpose of treating obesity is not weight loss alone but improving health, so the narrative needs to change from weight to blood pressure, glucose tolerance, physical fitness, etc. Many physicians believe that weight loss is an unwinnable battle but there are several well conducted studies in which primary care, supported by specialists, can deliver successful clinical weight loss. Specialist medical and surgical care for obesity will be required for complex cases and is essential for overseeing long-term postsurgical follow-up to prevent and treat nutritional and metabolic complications. Obesity management suffers from a lack of coherent national public health policies, fragmentation of care and a lack of knowledge of what successful treatment entails. Health benefits do not require a return to a healthy BMI.
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Índice de Massa Corporal , Obesidade/terapia , Saúde Pública/métodos , Redução de Peso , Peso Corporal , Doenças Cardiovasculares/epidemiologia , Doenças Cardiovasculares/prevenção & controle , Comorbidade , Exercício Físico , Conhecimentos, Atitudes e Prática em Saúde , Serviços de Saúde/normas , Nível de Saúde , Humanos , Neoplasias/epidemiologia , Neoplasias/prevenção & controle , Obesidade/epidemiologia , Saúde Pública/normas , Reino Unido/epidemiologiaRESUMO
Obesity surgery is an appropriate treatment option for patients with severe and complex obesity and helps in the improvement of comorbidities. In the first 2 years following surgery, follow-up is provided by the obesity surgery centre. Ongoing care is then usually returned to the general practitioner. Patients need access to ongoing support and monitoring otherwise may be at risk of developing nutritional deficiencies such as anaemia or protein malnutrition. The British Obesity and Metabolic Surgery Society have developed guidelines on nutritional monitoring and nutritional supplements to support both bariatric centres and general practitioners. The Royal College of General Practitioners and BOMSS have worked collaboratively to develop Ten Top Tips for the management of obesity surgery patients to aid with the long-term management in primary care. Women, planning to get pregnant, need access to preconception advice and additional monitoring during pregnancy. It is essential that long-term data are collected and inputted into the National Bariatric Surgery Register. Obesity surgery improves comorbidities; however, patients must have access to long-term nutritional monitoring.
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Cirurgia Bariátrica/métodos , Necessidades Nutricionais , Obesidade Mórbida/cirurgia , Cuidados Pós-Operatórios/métodos , Adulto , Serviços de Planejamento Familiar , Feminino , Seguimentos , Humanos , Guias de Prática Clínica como Assunto , Gravidez , Fatores de TempoRESUMO
PURPOSE: The focus of measuring success in obesity treatment is shifting from weight loss to patients' health and quality of life. The objective of this study was to select a core set of patient-reported outcomes and patient-reported outcome measures to be used in clinical obesity care. MATERIALS AND METHODS: The Standardizing Quality of Life in Obesity Treatment III, face-to-face hybrid consensus meeting, including people living with obesity as well as healthcare providers, was held in Maastricht, the Netherlands, in 2022. It was preceded by two prior multinational consensus meetings and a systematic review. RESULTS: The meeting was attended by 27 participants, representing twelve countries from five continents. The participants included healthcare providers, such as surgeons, endocrinologists, dietitians, psychologists, researchers, and people living with obesity, most of whom were involved in patient representative networks. Three patient-reported outcome measures (patient-reported outcomes) were selected: the Impact of Weight on Quality of Life-Lite (self-esteem) measure, the BODY-Q (physical function, physical symptoms, psychological function, social function, eating behavior, and body image), and the Quality of Life for Obesity Surgery questionnaire (excess skin). No patient-reported outcome measure was selected for stigma. CONCLUSION: A core set of patient-reported outcomes and patient-reported outcome measures for measuring quality of life in clinical obesity care is established incorporating patients' and experts' opinions. This set should be used as a minimum for measuring quality of life in routine clinical practice. It is essential that individual patient-reported outcome measure scores are shared with people living with obesity in order to enhance patient engagement and shared decision-making.
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Obesidade , Medidas de Resultados Relatados pelo Paciente , Qualidade de Vida , Humanos , Obesidade/terapia , Obesidade/psicologia , Países Baixos , Feminino , Masculino , Inquéritos e Questionários , Imagem Corporal/psicologia , Autoimagem , Cirurgia Bariátrica , Redução de Peso , AdultoRESUMO
Metabolic and bariatric surgery (MBS) is widely considered the most effective option for treating obesity, a chronic, relapsing, and progressive disease. Recently, the American Society of Metabolic and Bariatric Surgery (ASMBS) and the International Federation for the Surgery of Obesity and Metabolic Disorders (IFSO) issued new guidelines on the indications for MBS, which have superseded the previous 1991 National Institutes of Health guidelines. The aim of this study is to establish the first set of consensus guidelines for selecting procedures in Class I and II obesity, using an Expert Modified Delphi Method. In this study, 78 experienced bariatric surgeons from 32 countries participated in a two-round Modified Delphi consensus voting process. The threshold for consensus was set at an agreement or disagreement of ≥ 70.0% among the experts. The experts reached a consensus on 54 statements. The committee of experts reached a consensus that MBS is a cost-effective treatment option for Class II obesity and for patients with Class I obesity who have not achieved significant weight loss through non-surgical methods. MBS was also considered suitable for patients with Type 2 diabetes mellitus (T2DM) and a body mass index (BMI) of 30 kg/m2 or higher. The committee identified intra-gastric balloon (IGB) as a treatment option for patients with class I obesity and endoscopic sleeve gastroplasty (ESG) as an option for patients with class I and II obesity, as well as for patients with T2DM and a BMI of ≥ 30 kg/m2. Sleeve gastrectomy (1) and Roux-en-Y gastric bypass (RYGB) were also recognized as viable treatment options for these patient groups. The committee also agreed that one anastomosis gastric bypass (OAGB) is a suitable option for patients with Class II obesity and T2DM, regardless of the presence or severity of obesity-related medical problems. The recommendations for selecting procedures in Class I and II obesity, developed through an Expert Modified Delphi Consensus, suggest that the use of standard primary bariatric endoscopic (IGB, ESG) and surgical procedures (SG, RYGB, OAGB) are acceptable in these patient groups, as consensus was reached regarding these procedures. However, randomized controlled trials are still needed in Class I and II Obesity to identify the best treatment approach for these patients in the future.
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Cirurgia Bariátrica , Diabetes Mellitus Tipo 2 , Derivação Gástrica , Obesidade Mórbida , Humanos , Técnica Delphi , Diabetes Mellitus Tipo 2/cirurgia , Obesidade/cirurgia , Cirurgia Bariátrica/métodos , Derivação Gástrica/métodos , Gastrectomia , Obesidade Mórbida/cirurgia , Resultado do Tratamento , Estudos RetrospectivosRESUMO
Severe malnutrition following one-anastomosis gastric bypass (OAGB) remains a concern. Fifty studies involving 49,991 patients were included in this review. In-hospital treatment for severe malnutrition was needed for 0.9% (n = 446) of patients. Biliopancreatic limb (BPL) length was 150 cm in five (1.1%) patients, > 150 cm in 151 (33.9%), and not reported in 290 (65%) patients. OAGB was revised to normal anatomy in 126 (28.2%), sleeve gastrectomy in 46 (10.3%), Roux-en-Y gastric bypass in 41 (9.2%), and shortening of BPL length in 17 (3.8%) patients. One hundred fifty-one (33.8%) patients responded to treatment; ten (2.2%) did not respond and was not reported in 285 (63.9%) patients. Eight (0.02%) deaths were reported. Standardisation of the OAGB technique along with robust prospective data collection is required to understand this serious problem.
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Derivação Gástrica , Desnutrição , Obesidade Mórbida , Desnutrição Proteico-Calórica , Humanos , Derivação Gástrica/métodos , Obesidade Mórbida/cirurgia , Desnutrição/etiologia , Desnutrição/cirurgia , Desnutrição Proteico-Calórica/etiologia , Gastrectomia/métodos , Estudos RetrospectivosRESUMO
BACKGROUND: Obesity affects 1.5 billion people worldwide, yet few are treated effectively and considerable variability exists in its management. In 2020, a joint International Federation of Surgery for Obesity and Metabolic Diseases (IFSO) and World Gastroenterology Organization (WGO) advisory committee initiated the drafting of consensus guidelines on obesity management, to be based on detailed literature reviews and the results of an extensive multi-disciplinary survey of intercontinental experts. This paper reports on the latter. The objective of this study is to identify areas of consensus and non-consensus among intercontinental, inter-disciplinary experts in obesity management. METHODS: Guided by an international consensus-survey expert, a three-round online Delphi survey was conducted in the summer of 2021 of international obesity-management experts spanning the fields of medicine, bariatric endoscopy and surgery, psychology, and nutrition. Issues like epidemiology and risk factors, patient selection for metabolic and bariatric surgery (ASMBS-Clinical-Issues-Committee, Surg Obes Relat Dis : Off J Am Soc Bariatric Surg. 8:e27-32, 1), psychological issues, patient preparation for MBS, bariatric endoscopy, and outcomes and follow-up were addressed. RESULTS: Ninety-four experts from six continents voted on 180 statements, with consensus reached on 158, including consensus agreement with 96 and disagreement with 24 statements (38 had other response options besides agree/disagree). Among unanimous opinions were the need for all medical societies to work together to address obesity, for regular regional and national obesity surveillance, for multi-disciplinary management, to recognize the increasing impact of childhood and adolescent obesity, to accept some weight regain as normal after MBS, and for life-long follow-up of MBS patients. CONCLUSIONS: Obesity is a major health issue that requires aggressive surveillance and thoughtful multidisciplinary management.
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Cirurgia Bariátrica , Gastroenterologia , Manejo da Obesidade , Obesidade Mórbida , Obesidade Infantil , Humanos , Adolescente , Obesidade Mórbida/cirurgia , Obesidade Infantil/cirurgia , Cirurgia Bariátrica/métodosRESUMO
MAJOR UPDATES TO 1991 NATIONAL INSTITUTES OF HEALTH GUIDELINES FOR BARIATRIC SURGERY: Metabolic and bariatric surgery (MBS) is recommended for individuals with a body mass index (BMI) >35 kg/m2, regardless of presence, absence, or severity of co-morbidities.MBS should be considered for individuals with metabolic disease and BMI of 30-34.9 kg/m2.BMI thresholds should be adjusted in the Asian population such that a BMI >25 kg/m2 suggests clinical obesity, and individuals with BMI >27.5 kg/m2 should be offered MBS.Long-term results of MBS consistently demonstrate safety and efficacy.Appropriately selected children and adolescents should be considered for MBS.(Surg Obes Relat Dis 2022; https://doi.org/10.1016/j.soard.2022.08.013 ) © 2022 American Society for Metabolic and Bariatric Surgery. All rights reserved.
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Cirurgia Bariátrica , Doenças Metabólicas , Obesidade Mórbida , Adolescente , Criança , Humanos , Estados Unidos/epidemiologia , Obesidade Mórbida/cirurgia , Obesidade/complicações , Obesidade/cirurgia , Cirurgia Bariátrica/métodos , Doenças Metabólicas/cirurgia , Índice de Massa CorporalRESUMO
Unlike various countries and organisations, including the World Health Organisation and the European Parliament, the United Kingdom does not formally recognise obesity as a disease. This report presents the discussion on the potential impact of defining obesity as a disease on the patient, the healthcare system, the economy, and the wider society. A group of speakers from a wide range of disciplines came together to debate the topic bringing their knowledge and expertise from backgrounds in medicine, psychology, economics, and politics as well as the experience of people living with obesity. The aim of their debate was not to decide whether obesity should be classified as a disease but rather to explore what the implications of doing so would be, what the gaps in the available data are, as well as to provide up-to-date information on the topic from experts in the field. There were four topics where speakers presented their viewpoints, each one including a question-and-answer section for debate. The first one focused on the impact that the recognition of obesity could have on people living with obesity regarding the change in their behaviour, either positive and empowering or more stigmatising. During the second one, the impact of defining obesity as a disease on the National Health Service and the wider economy was discussed. The primary outcome was the need for more robust data as the one available does not represent the actual cost of obesity. The third topic was related to the policy implications regarding treatment provision, focusing on the public's power to influence policy. Finally, the last issue discussed, included the implications of public health actions, highlighting the importance of the government's actions and private stakeholders. The speakers agreed that no matter where they stand on this debate, the goal is common: to provide a healthcare system that supports and protects the patients, strategies that protect the economy and broader society, and policies that reduce stigma and promote health equity. Many questions are left to be answered regarding how these goals can be achieved. However, this discussion has set a good foundation providing evidence that can be used by the public, clinicians, and policymakers to make that happen.
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INTRODUCTION: Obesity significantly increases the risk of developing (or worsening) more than 200 chronic diseases, and it is also a risk factor for severe COVID-19. With the rising prevalence of obesity in the UK, there is a need to develop obesity care competencies that apply to healthcare professionals (HCPs) at all levels of the health service, to increase the capacity for contemporary, evidence-based treatment that is effective, compassionate, and avoids stigmatising patients. METHODS: A UK Obesity Care Competencies Working Group consisting of experts by profession and experts by experience was created to provide a framework of obesity care competencies for HCPs involved in specialist obesity care (tiers 2-4 in the UK). The framework was adapted from a set of competencies recently published by the USA-based Obesity Medicine Education Collaborative (OMEC) and was intended to be adaptable to nurses and allied health professionals, as well as physicians, owing to the multidisciplinary team approach used in healthcare in the UK. RESULTS: The UK Obesity Care Competencies Working Group developed a set of 29 competencies, divided into five focal areas, namely obesity knowledge, patient care and procedural skills, practice-based learning and improvement, professionalism and interpersonal communication skills, and systems-based practice. The working group recommends that the obesity care competencies are targeted at HCPs training as specialists. The competencies could be imported into existing training programmes to help standardise obesity-related medical education and could also be used to direct a new General Practitioner with Extended Role (GPwER) qualification. CONCLUSION: This list of obesity care competencies aims to provide an initial framework to improve education for HCPs and therefore to improve patient care in obesity. The acceptance and integration of these competencies into the healthcare system should provide a stepping stone toward addressing trends in health inequality.
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COVID-19 , Competência Clínica , Atenção à Saúde , Disparidades nos Níveis de Saúde , Humanos , Obesidade/terapia , Reino UnidoRESUMO
Tailoring the solution chemistry of metal halide perovskites requires a detailed understanding of precursor aggregation and coordination. In this work, we use various scattering techniques, including dynamic light scattering (DLS), small angle neutron scattering (SANS), and spin-echo SANS (SESANS) to probe the nanostructures from 1 nm to 10 µm within two different lead-halide perovskite solution inks (MAPbI3 and a triple-cation mixed-halide perovskite). We find that DLS can misrepresent the size distribution of the colloidal dispersion and use SANS/SESANS to confirm that these perovskite solutions are mostly comprised of 1-2 nm-sized particles. We further conclude that if there are larger colloids present, their concentration must be <0.005% of the total dispersion volume. With SANS, we apply a simple fitting model for two component microemulsions (Teubner-Strey), demonstrating this as a potential method to investigate the structure, chemical composition, and colloidal stability of perovskite solutions, and we here show that MAPbI3 solutions age more drastically than triple cation solutions.
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Self-assembled monolayers (SAMs) are becoming widely utilized as hole-selective layers in high-performance p-i-n architecture perovskite solar cells. Ultrasonic spray coating and airbrush coating are demonstrated here as effective methods to deposit MeO-2PACz; a carbazole-based SAM. Potential dewetting of hybrid perovskite precursor solutions from this layer is overcome using optimized solvent rinsing protocols. The use of air-knife gas-quenching is then explored to rapidly remove the volatile solvent from an MAPbI3 precursor film spray-coated onto an MeO-2PACz SAM, allowing fabrication of p-i-n devices with power conversion efficiencies in excess of 20%, with all other layers thermally evaporated. This combination of deposition techniques is consistent with a rapid, roll-to-roll manufacturing process for the fabrication of large-area solar cells.
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Spray coating is an industrially mature technique used to deposit thin films that combines high throughput with the ability to coat nonplanar surfaces. Here, we explore the use of ultrasonic spray coating to fabricate perovskite solar cells (PSCs) over rigid, nonplanar surfaces without problems caused by solution dewetting and subsequent "run-off". Encouragingly, we find that PSCs can be spray-coated using our processes onto glass substrates held at angles of inclination up to 45° away from the horizontal, with such devices having comparable power conversion efficiencies (up to 18.3%) to those spray-cast onto horizontal substrates. Having established that our process can be used to create PSCs on surfaces that are not horizontal, we fabricate devices over a convex glass substrate, with devices having a maximum power conversion efficiency of 12.5%. To our best knowledge, this study represents the first demonstration of a rigid, curved perovskite solar cell. The integration of perovskite photovoltaics onto curved surfaces will likely find direct applications in the aerospace and automotive sectors.
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Major updates to 1991 National Institutes of Health guidelines for bariatric surgery.