96 research outputs found
Leveraging Low-Energy Structural Thermodynamics in Halide Perovskites
Metal halide perovskites (MHPs) combine extraordinary optoelectronic
properties with chemical and mechanical properties not found in their
semiconductor counterparts. For instance, they exhibit optoelectronic
properties on par with single-crystalline gallium arsenide yet exhibit
near-zero formation energies. The small lattice energy of MHPs means they
undergo a rich diversity of polymorphism near standard conditions similar to
organic materials. MHPs also demonstrate ionic transport as high as
state-of-the-art battery electrodes. The most widespread applications for metal
halide perovskites (e.g. photovoltaics and solid-state lighting) typically view
low formation energies, polymorphism, and high ion transport as a nuisance that
should be eliminated. Here, we put these properties into perspective by
comparing them to other technologically relevant semiconductors in order to
highlight how unique this combination of properties is for semiconductors and
to illustrate ways to leverage these properties in emerging applications
Thermochromic Metal Halide Perovskite Windows with Ideal Transition Temperatures
Urban centers across the globe are responsible for a significant fraction of
energy consumption and CO2 emission. As urban centers continue to grow, the
popularity of glass as cladding material in urban buildings is an alarming
trend. Dynamic windows reduce heating and cooling loads in buildings by passive
heating in cold seasons and mitigating solar heat gain in hot seasons. In this
work, we develop a mesoscopic building energy model that demonstrates reduced
building energy consumption when thermochromic windows are employed. Savings
are realized across eight disparate climate zones of the United States. We use
the model to determine the ideal critical transition temperature of 20 to 27.5
{\deg}C for thermochromic windows based on metal halide perovskite materials.
Ideal transition temperatures are realized experimentally in composite metal
halide perovskite film composed of perovskite crystals and an adjacent
reservoir phase. The transition temperature is controlled by co-intercalating
methanol, instead of water, with methylammonium iodide and tailoring the
hydrogen-bonding chemistry of the reservoir phase. Thermochromic windows based
on metal halide perovskites represent a clear opportunity to mitigate the
effects of energy-hungry buildings
CsIâAntisolvent Adduct Formation in AllâInorganic Metal Halide Perovskites
The excellent optoelectronic properties demonstrated by hybrid organic/inorganic metal halide perovskites are all predicated on precisely controlling the exact nucleation and crystallization dynamics that occur during film formation. In general, highâperformance thin films are obtained by a method commonly called solvent engineering (or antisolvent quench) processing. The solvent engineering method removes excess solvent, but importantly leaves behind solvent that forms chemical adducts with the leadâhalide precursor salts. These adductâbased precursor phases control nucleation and the growth of the polycrystalline domains. There has not yet been a comprehensive study comparing the various antisolvents used in different perovskite compositions containing cesium. In addition, there have been no reports of solvent engineering for high efficiency in allâinorganic perovskites such as CsPbI3. In this work, inorganic perovskite composition CsPbI3 is specifically targeted and unique adducts formed between CsI and precursor solvents and antisolvents are found that have not been observed for other Aâsite cation salts. These CsI adducts control nucleation more so than the PbI2âdimethyl sulfoxide (DMSO) adduct and demonstrate how the Aâsite plays a significant role in crystallization. The use of methyl acetate (MeOAc) in this solvent engineering approach dictates crystallization through the formation of a CsIâMeOAc adduct and results in solar cells with a power conversion efficiency of 14.4%.It is found that unique adducts form between CsI and dimethyl sulfoxide (DMSO) and certain antisolvents, such as methyl acetate, during film formation of the allâinorganic perovskite CsPbI3. These adducts significantly influence crystallization and the power conversion efficiency of the resulting solar cells.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154525/1/aenm201903365-sup-0001-SuppMat.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154525/2/aenm201903365.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154525/3/aenm201903365_am.pd
CsIâAntisolvent Adduct Formation in AllâInorganic Metal Halide Perovskites
The excellent optoelectronic properties demonstrated by hybrid organic/inorganic metal halide perovskites are all predicated on precisely controlling the exact nucleation and crystallization dynamics that occur during film formation. In general, highâperformance thin films are obtained by a method commonly called solvent engineering (or antisolvent quench) processing. The solvent engineering method removes excess solvent, but importantly leaves behind solvent that forms chemical adducts with the leadâhalide precursor salts. These adductâbased precursor phases control nucleation and the growth of the polycrystalline domains. There has not yet been a comprehensive study comparing the various antisolvents used in different perovskite compositions containing cesium. In addition, there have been no reports of solvent engineering for high efficiency in allâinorganic perovskites such as CsPbI3. In this work, inorganic perovskite composition CsPbI3 is specifically targeted and unique adducts formed between CsI and precursor solvents and antisolvents are found that have not been observed for other Aâsite cation salts. These CsI adducts control nucleation more so than the PbI2âdimethyl sulfoxide (DMSO) adduct and demonstrate how the Aâsite plays a significant role in crystallization. The use of methyl acetate (MeOAc) in this solvent engineering approach dictates crystallization through the formation of a CsIâMeOAc adduct and results in solar cells with a power conversion efficiency of 14.4%.It is found that unique adducts form between CsI and dimethyl sulfoxide (DMSO) and certain antisolvents, such as methyl acetate, during film formation of the allâinorganic perovskite CsPbI3. These adducts significantly influence crystallization and the power conversion efficiency of the resulting solar cells.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154525/1/aenm201903365-sup-0001-SuppMat.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154525/2/aenm201903365.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154525/3/aenm201903365_am.pd
Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine
[This corrects the article DOI: 10.1186/s13054-016-1208-6.]
Apophis planetary defense campaign
We describe results of a planetary defense exercise conducted during the close approach to Earth by the near-Earth asteroid (99942) Apophis during 2020 Decemberâ2021 March. The planetary defense community has been conducting observational campaigns since 2017 to test the operational readiness of the global planetary defense capabilities. These community-led global exercises were carried out with the support of NASA's Planetary Defense Coordination Office and the International Asteroid Warning Network. The Apophis campaign is the third in our series of planetary defense exercises. The goal of this campaign was to recover, track, and characterize Apophis as a potential impactor to exercise the planetary defense system including observations, hypothetical risk assessment and risk prediction, and hazard communication. Based on the campaign results, we present lessons learned about our ability to observe and model a potential impactor. Data products derived from astrometric observations were available for inclusion in our risk assessment model almost immediately, allowing real-time updates to the impact probability calculation and possible impact locations. An early NEOWISE diameter measurement provided a significant improvement in the uncertainty on the range of hypothetical impact outcomes. The availability of different characterization methods such as photometry, spectroscopy, and radar provided robustness to our ability to assess the potential impact risk
Italian guidelines for primary headaches: 2012 revised version
The first edition of the Italian diagnostic and therapeutic guidelines for primary headaches in adults was published in J Headache Pain 2(Suppl. 1):105â190 (2001). Ten years later, the guideline committee of the Italian Society for the Study of Headaches (SISC) decided it was time to update therapeutic guidelines. A literature search was carried out on Medline database, and all articles on primary headache treatments in English, German, French and Italian published from February 2001 to December 2011 were taken into account. Only randomized controlled trials (RCT) and meta-analyses were analysed for each drug. If RCT were lacking, open studies and case series were also examined. According to the previous edition, four levels of recommendation were defined on the basis of levels of evidence, scientific strength of evidence and clinical effectiveness. Recommendations for symptomatic and prophylactic treatment of migraine and cluster headache were therefore revised with respect to previous 2001 guidelines and a section was dedicated to non-pharmacological treatment. This article reports a summary of the revised version published in extenso in an Italian version
Photography-based taxonomy is inadequate, unnecessary, and potentially harmful for biological sciences
The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & NemĂ©sio 2007; Donegan 2008, 2009; NemĂ©sio 2009aâb; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported
by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per the editorial rules of Nature) was submitted to Nature, which on
18 October 2016 refused to publish it. As we think this problem is a very important one for zoological taxonomy, this text is published here exactly as submitted to Nature, followed by the list of the 493 taxonomists and collection-based
researchers who signed it in the short time span from 20 September to 6 October 2016
Choice and self: how synchronic and diachronic identity shape choices and decision making
Multiorgan MRI findings after hospitalisation with COVID-19 in the UK (C-MORE): a prospective, multicentre, observational cohort study
Introduction:
The multiorgan impact of moderate to severe coronavirus infections in the post-acute phase is still poorly understood. We aimed to evaluate the excess burden of multiorgan abnormalities after hospitalisation with COVID-19, evaluate their determinants, and explore associations with patient-related outcome measures.
Methods:
In a prospective, UK-wide, multicentre MRI follow-up study (C-MORE), adults (aged â„18 years) discharged from hospital following COVID-19 who were included in Tier 2 of the Post-hospitalisation COVID-19 study (PHOSP-COVID) and contemporary controls with no evidence of previous COVID-19 (SARS-CoV-2 nucleocapsid antibody negative) underwent multiorgan MRI (lungs, heart, brain, liver, and kidneys) with quantitative and qualitative assessment of images and clinical adjudication when relevant. Individuals with end-stage renal failure or contraindications to MRI were excluded. Participants also underwent detailed recording of symptoms, and physiological and biochemical tests. The primary outcome was the excess burden of multiorgan abnormalities (two or more organs) relative to controls, with further adjustments for potential confounders. The C-MORE study is ongoing and is registered with ClinicalTrials.gov, NCT04510025.
Findings:
Of 2710 participants in Tier 2 of PHOSP-COVID, 531 were recruited across 13 UK-wide C-MORE sites. After exclusions, 259 C-MORE patients (mean age 57 years [SD 12]; 158 [61%] male and 101 [39%] female) who were discharged from hospital with PCR-confirmed or clinically diagnosed COVID-19 between March 1, 2020, and Nov 1, 2021, and 52 non-COVID-19 controls from the community (mean age 49 years [SD 14]; 30 [58%] male and 22 [42%] female) were included in the analysis. Patients were assessed at a median of 5·0 months (IQR 4·2â6·3) after hospital discharge. Compared with non-COVID-19 controls, patients were older, living with more obesity, and had more comorbidities. Multiorgan abnormalities on MRI were more frequent in patients than in controls (157 [61%] of 259 vs 14 [27%] of 52; p<0·0001) and independently associated with COVID-19 status (odds ratio [OR] 2·9 [95% CI 1·5â5·8]; padjusted=0·0023) after adjusting for relevant confounders. Compared with controls, patients were more likely to have MRI evidence of lung abnormalities (p=0·0001; parenchymal abnormalities), brain abnormalities (p<0·0001; more white matter hyperintensities and regional brain volume reduction), and kidney abnormalities (p=0·014; lower medullary T1 and loss of corticomedullary differentiation), whereas cardiac and liver MRI abnormalities were similar between patients and controls. Patients with multiorgan abnormalities were older (difference in mean age 7 years [95% CI 4â10]; mean age of 59·8 years [SD 11·7] with multiorgan abnormalities vs mean age of 52·8 years [11·9] without multiorgan abnormalities; p<0·0001), more likely to have three or more comorbidities (OR 2·47 [1·32â4·82]; padjusted=0·0059), and more likely to have a more severe acute infection (acute CRP >5mg/L, OR 3·55 [1·23â11·88]; padjusted=0·025) than those without multiorgan abnormalities. Presence of lung MRI abnormalities was associated with a two-fold higher risk of chest tightness, and multiorgan MRI abnormalities were associated with severe and very severe persistent physical and mental health impairment (PHOSP-COVID symptom clusters) after hospitalisation.
Interpretation:
After hospitalisation for COVID-19, people are at risk of multiorgan abnormalities in the medium term. Our findings emphasise the need for proactive multidisciplinary care pathways, with the potential for imaging to guide surveillance frequency and therapeutic stratification
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