High-entropy alloy screening for halide perovskites.

As the concept of high-entropy alloying (HEA) extends beyond metals, new materials screening methods are needed. Halide perovskites (HP) are a prime case study because greater stability is needed for photovoltaics applications, and there are 322 experimentally observed HP end-members, which leads to more than 1057 potential alloys. We screen HEAHP by first calculating the configurational entropy of 106 equimolar alloys with experimentally observed end-members. To estimate enthalpy at low computational cost, we turn to the delta-lattice parameter approach, a well-known method for predicting III-V alloy miscibility. To generalize the approach for non-cubic crystals, we introduce the parameter of unit cell volume coefficient of variation (UCV), which does a good job of predicting the experimental HP miscibility data. We use plots of entropy stabilization versus UCV to screen promising alloys and identify 102 HEAHP of interest.

Understanding opportunities and challenges with telemedicine-delivered buprenorphine during the COVID-19 pandemic.

INTRODUCTION: Opioid use disorder (OUD) is a debilitating illness that remains a serious public health issue in the United States. Use of telemedicine to deliver medications for the treatment of OUD (MOUD) was limited until the confluence of the COVID-19 and opioid addiction epidemics in spring 2020. Starting in spring 2020, the Department of Veterans Health Affairs (VHA) transitioned from in-person to mostly telemedicine-delivered OUD care to reduce COVID-19 transmission among veterans and providers. To gain a nuanced understanding of provider perspectives on MOUD care delivery using telemedicine, we conducted semi-structured interviews with VHA providers who were using telehealth to deliver MOUD care. METHODS: We conducted semi-structed Zoom interviews with VA clinicians at nine VA Medical Centers (VAMCs) in eight states. Potential study participants were identified as providers who were involved in referrals and provision of buprenorphine treatment for chronic pain and opioid addiction. Audio-recordings of all interviews were transcribed and entered into Atlas. Ti qualitative analysis software. The study team analyzed the transcripts for major themes related to tele-prescribing practices for buprenorphine. RESULTS: Twenty-three VA providers participated in the study, representing 32% of all providers invited to participate in the study. The research team identified the following four themes: (1) COVID-19 spurred a seismic shift in OUD treatment; (2) Video calls provided a rare window into veterans' lives; (3) Providers experienced numerous challenges to virtual visits; and (4) Providers wrestled with paternalism and trust. CONCLUSIONS: The pandemic accelerated the movement toward harm reduction approaches. Prior to the pandemic, stringent requirements existed for patients receiving MOUD care. Providers in this study reflected on the need for these requirements (e.g., in-person visits, toxicology screens) and how reducing this monitoring implied more trust in patients' autonomous decisions. Providers' observation that videoconferencing offered them a window into patients' lives may offer some ways to improve rapport, and research should explore how best to incorporate the additional information conveyed in virtual visits.

Increasing buprenorphine access for veterans with opioid use disorder in rural clinics using telemedicine.

Background:Having prescribers use clinical video teleconferencing (telemedicine) to prescribe buprenorphine to people with opioid use disorder (OUD) has shown promise but its implementation is challenging. We describe barriers, facilitators and lessons learned while implementing a system to remotely prescribe buprenorphine to Veterans in rural settings. Methods: We conducted a quality improvement project aimed at increasing the availability of medications for OUD (MOUD) to Veterans. This project focused on tele-prescribing buprenorphine to rural sites via a hub (centralized prescribers) and spoke (rural clinics) model. After soliciting a wide-range of inputs from site visits, qualitative interviews of key stakeholders at rural sites, and review of preliminary cases, a "how-to" toolkit was developed and iteratively refined to guide tele-prescribing of buprenorphine. After internal and external facilitation strategies were employed, Veterans with OUD at three clinics were transitioned to buprenorphine treatment via telemedicine. Results: Factors impacting adoption of the tele-prescribing intervention were mapped to the Consolidated Framework for Implementation Research (CFIR) constructs. Barriers to adoption included concerns about legality of tele-prescribing a controlled substance, conflicting interests between different stakeholders, and coordination with an existing buprenorphine program requiring more attendance and abstinence from Veterans than the tele-prescribing program required. Factors facilitating adoption included a sense of mission around combating the opioid epidemic, preexisting use of and comfort with tele-prescribing, and rural sites' control over Veterans referred to tele-prescribers. A total of 12 patients from rural areas were successfully transitioned onto buprenorphine, of whom 9 remained on buprenorphine 6 months after initiation of treatment. Conclusions: Implementing tele-prescribing was negotiated with stakeholders at the target clinics and operationalized in a toolkit to guide future efforts. Implementation issues can be addressed by activities that foster collaboration between hubs (centralized prescribers) and spokes (rural clinics) and by a toolkit that operationalizes tele-prescribing procedures.

The intertwined expansion of telehealth and buprenorphine access from a prescriber hub.

In this manuscript, we describe how efforts to increase access to buprenorphine for Opioid Use Disorder (OUD) through a telemedicine hub before and since the COVID-19 pandemic have played out in the Veterans Healthcare Administration (VHA) in New England. We look at how the COVID-19 pandemic and subsequent spike in opioid overdoses tilted the risk: benefit calculation for tele-prescribing a controlled substance such as buprenorphine toward expanding access to tele-buprenorphine. We conclude that there is a need for tele-buprenorphine hubs that can fill gaps in geographically dispersed healthcare systems.

Reversible multicolor chromism in layered formamidinium metal halide perovskites.

Metal halide perovskites feature crystalline-like electronic band structures and liquid-like physical properties. The crystal-liquid duality enables optoelectronic devices with unprecedented performance and a unique opportunity to chemically manipulate the structure with low energy input. In this work, we leverage the low formation energy of metal halide perovskites to demonstrate multicolor reversible chromism. We synthesized layered Ruddlesden-Popper FAn+1PbnX3n+1 (FA = formamidinium, X = I, Br; n = number of layers = 1, 2, 3 … ∞) and reversibly tune the dimensionality (n) by modulating the strength and number of H-bonds in the system. H-bonding was controlled by exposure to solvent vapor (solvatochromism) or temperature change (thermochromism), which shuttles FAX salt pairs between the FAn+1PbnX3n+1 domains and adjacent FAX "reservoir" domains. Unlike traditional chromic materials that only offer a single-color transition, FAn+1PbnX3n+1 films reversibly switch between multiple colors including yellow, orange, red, brown, and white/colorless. Each colored phase exhibits distinct optoelectronic properties characteristic of 2D superlattice materials with tunable quantum well thickness.

Medical-Surgical Hospitalization Among Veterans With Psychiatric and Substance Use Disorders.

BACKGROUND: Mental illness is associated with an increased risk for medical hospitalizations. OBJECTIVE: This study investigates the degree to which nonpsychiatric factors account for these hospitalizations. METHODS: Using National Veterans Health Administration (VHA) fiscal year 2012 data for 2 million veterans under the age of 60 years, hospitalization risks were compared for veterans with and without mental illnesses. Bivariate analyses identified factors associated with mental illnesses. Multiple logistic regression was used to calculate adjusted psychiatric risk for medical hospitalization, controlling for these factors. RESULTS: Veterans carrying mental health diagnoses were at increased risk for hospitalizations (odds ratio [OR] = 2.52, 2.48-2.55). Among individual diagnoses, alcohol use disorder (AUD) (OR = 3.84, 3.78-3.91) and drug use disorders (OR = 4.58, 4.50-4.66) were associated with the highest risk. After adjusting for nonpsychiatric medical, addiction-related, and care utilization factors and the use of outpatient medical services, veterans with mental illnesses were at increased risk for medical hospitalization (OR = 1.43, 1.41-1.45). After further adjustment for AUD and drug use, hospitalization risk decreased further (OR = 1.23, 1.21-1.26) while the association of AUD and hospitalizations remained high (OR = 1.77, 1.73-1.81). CONCLUSIONS: Medical comorbidities and service use accounted for most, but not all, of the increased risk of medical hospitalizations associated with mental illness. Even after accounting for poor health, AUD remained strongly associated with medical hospitalization.

The existence and impact of persistent ferroelectric domains in MAPbI3.

Methylammonium lead iodide (MAPbI3) exhibits exceptional photovoltaic performance, but there remains substantial controversy over the existence and impact of ferroelectricity on the photovoltaic response. We confirm ferroelectricity in MAPbI3 single crystals and demonstrate mediation of the electronic response by ferroelectric domain engineering. The ferroelectric response sharply declines above 57°C, consistent with the tetragonal-to-cubic phase transition. Concurrent band excitation piezoresponse force microscopy-contact Kelvin probe force microscopy shows that the measured response is not dominated by spurious electrostatic interactions. Large signal poling (>16 V/cm) orients the permanent polarization into large domains, which show stabilization over weeks. X-ray photoemission spectroscopy results indicate a shift of 400 meV in the binding energy of the iodine core level peaks upon poling, which is reflected in the carrier concentration results from scanning microwave impedance microscopy. The ability to control the ferroelectric response provides routes to increase device stability and photovoltaic performance through domain engineering.

Direct Measurements of Carrier Transport in Polycrystalline Methylammonium Lead Iodide Perovskite Films with Transient Grating Spectroscopy.

Hybrid organic-inorganic halide perovskites have been proposed in many optoelectronic applications, but critical to their increasing functionality and utility is understanding and controlling carrier transport. Here, we use light-induced transient grating spectroscopy to probe directly carrier transport in polycrystalline methylammonium lead iodide perovskite thin films using a weakly perturbative and noncontact method. The data reveal intrinsic diffusion characteristics of the charge carriers in the material and agree well with a simulated model of charge transport in which grain boundaries act as barriers to carrier movement.

A Focused Addiction Curriculum and Its Impact on Student Knowledge, Attitudes, and Confidence in the Treatment of Patients with Substance Use.

BACKGROUND: Assessment of attitudes towards addiction in medical students has largely gone unexplored. This study examines the impact of a supplemental substance use disorder curriculum in the psychiatry clerkship on medical student attitudes towards addiction. METHODS: The curriculum was only administered to students at one clerkship site. Subsequently, medical students were surveyed across all sites regarding their attitudes towards addiction. RESULTS: The survey response rate was 37.5% (N = 75/200), with 25 (33%) completing the supplemental addiction curriculum. In bivariate analysis, medical students receiving the curriculum were more likely to express confidence in managing patients with alcohol and opiate use disorders (T = 2.01, p = 0.05) and were more knowledgeable about Alcoholics Anonymous (AA) as a treatment option available to patients (T = 2.27, p = 0.03). CONCLUSIONS: A supplemental addiction curriculum can improve medical student confidence in managing substance-using patients as well as improve knowledge of AA.

Switchable photovoltaic windows enabled by reversible photothermal complex dissociation from methylammonium lead iodide.

Materials with switchable absorption properties have been widely used for smart window applications to reduce energy consumption and enhance occupant comfort in buildings. In this work, we combine the benefits of smart windows with energy conversion by producing a photovoltaic device with a switchable absorber layer that dynamically responds to sunlight. Upon illumination, photothermal heating switches the absorber layer-composed of a metal halide perovskite-methylamine complex-from a transparent state (68% visible transmittance) to an absorbing, photovoltaic colored state (less than 3% visible transmittance) due to dissociation of methylamine. After cooling, the methylamine complex is re-formed, returning the absorber layer to the transparent state in which the device acts as a window to visible light. The thermodynamics of switching and performance of the device are described. This work validates a photovoltaic window technology that circumvents the fundamental tradeoff between efficient solar conversion and high visible light transmittance that limits conventional semitransparent PV window designs.

Synthesis and Spectroscopy of Silver-Doped PbSe Quantum Dots.

Electronic impurity doping of bulk semiconductors is an essential component of semiconductor science and technology. Yet there are only a handful of studies demonstrating control of electronic impurities in semiconductor nanocrystals. Here, we studied electronic impurity doping of colloidal PbSe quantum dots (QDs) using a postsynthetic cation exchange reaction in which Pb is exchanged for Ag. We found that varying the concentration of dopants exposed to the as-synthesized PbSe QDs controls the extent of exchange. The electronic impurity doped QDs exhibit the fundamental spectroscopic signatures associated with injecting a free charge carrier into a QD under equilibrium conditions, including a bleach of the first exciton transition and the appearance of a quantum-confined, low-energy intraband absorption feature. Photoelectron spectroscopy confirms that Ag acts as a p-type dopant for PbSe QDs and infrared spectroscopy is consistent with k·p calculations of the size-dependent intraband transition energy. We find that to bleach the first exciton transition by an average of 1 carrier per QD requires that approximately 10% of the Pb be replaced by Ag. We hypothesize that the majority of incorporated Ag remains at the QD surface and does not interact with the core electronic states of the QD. Instead, the excess Ag at the surface promotes the incorporation of <1% Ag into the QD core where it causes p-type doping behavior.

Comprehensive services delivery and emergency department use among chronically homeless adults.

Homeless adults use emergency department (ED) services more frequently than other adults, but the relationships between homelessness, health status, outpatient service use, and ED utilization are poorly understood. Data from the Collaborative Initiative to Help End Chronic Homelessness (CICH) were used to compare ED use among chronically homeless adults receiving comprehensive housing, case management, mental health, addiction, and primary care services through CICH at 5 U.S. sites (n = 274) and ED use among comparison group clients receiving generally available community services (n = 116) at the same sites. Multiple imputation was used to account for missing data and differential rates of attrition between the cohorts. Longitudinal models were constructed to compare ED use between the 2 groups during the first year after initiation of CICH services. A mediation analysis was performed to determine the relative contributions of being housed, the receipt of outpatient services, and health status to group differences in ED utilization. Participants receiving CICH services were significantly less likely to report ED use (odds ratio = 0.78, 95% confidence interval [0.65, 0.93]) in the year after program entry. Decreased ED use was primarily mediated by decreased homelessness-not by increased access to other services or health status. This suggests that becoming housed is a key driver of reduced ED utilization and that efforts to provide housing for homeless adults may result in significantly decreased ED use. Further research is needed to determine the long-term effects of housing on health status and to develop services to improve health outcomes. (PsycINFO Database Record

Quantum dot-induced phase stabilization of α-CsPbI3 perovskite for high-efficiency photovoltaics.

We show nanoscale phase stabilization of CsPbI3 quantum dots (QDs) to low temperatures that can be used as the active component of efficient optoelectronic devices. CsPbI3 is an all-inorganic analog to the hybrid organic cation halide perovskites, but the cubic phase of bulk CsPbI3 (α-CsPbI3)-the variant with desirable band gap-is only stable at high temperatures. We describe the formation of α-CsPbI3 QD films that are phase-stable for months in ambient air. The films exhibit long-range electronic transport and were used to fabricate colloidal perovskite QD photovoltaic cells with an open-circuit voltage of 1.23 volts and efficiency of 10.77%. These devices also function as light-emitting diodes with low turn-on voltage and tunable emission.

Mechanism for rapid growth of organic-inorganic halide perovskite crystals.

Optoelectronic devices based on hybrid halide perovskites have shown remarkable progress to high performance. However, despite their apparent success, there remain many open questions about their intrinsic properties. Single crystals are often seen as the ideal platform for understanding the limits of crystalline materials, and recent reports of rapid, high-temperature crystallization of single crystals should enable a variety of studies. Here we explore the mechanism of this crystallization and find that it is due to reversible changes in the solution where breaking up of colloids, and a change in the solvent strength, leads to supersaturation and subsequent crystallization. We use this knowledge to demonstrate a broader range of processing parameters and show that these can lead to improved crystal quality. Our findings are therefore of central importance to enable the continued advancement of perovskite optoelectronics and to the improved reproducibility through a better understanding of factors influencing and controlling crystallization.

Directly Activating the Integrin αIIbß3 Initiates Outside-In Signaling by Causing αIIbß3 Clustering.

αIIbß3 activation in platelets is followed by activation of the tyrosine kinase c-Src associated with the carboxyl terminus of the ß3 cytosolic tail. Exogenous peptides designed to interact with the αIIb transmembrane (TM) domain activate single αIIbß3 molecules in platelets by binding to the αIIb TM domain and causing separation of the αIIbß3 TM domain heterodimer. Here we asked whether directly activating single αIIbß3 molecules in platelets using the designed peptide anti-αIIb TM also initiates αIIbß3-mediated outside-in signaling by causing activation of ß3-associated c-Src. Anti-αIIb TM caused activation of ß3-associated c-Src and the kinase Syk, but not the kinase FAK, under conditions that precluded extracellular ligand binding to αIIbß3. c-Src and Syk are activated by trans-autophosphorylation, suggesting that activation of individual αIIbß3 molecules can initiate αIIbß3 clustering in the absence of ligand binding. Consistent with this possibility, incubating platelets with anti-αIIb TM resulted in the redistribution of αIIbß3 from a homogenous ring located at the periphery of discoid platelets into nodular densities consistent with clustered αIIbß3. Thus, these studies indicate that not only is resting αIIbß3 poised to undergo a conformational change that exposes its ligand-binding site, but it is poised to rapidly assemble into intracellular signal-generating complexes as well.

The Tyrosine Kinase c-Src Specifically Binds to the Active Integrin αIIbß3 to Initiate Outside-in Signaling in Platelets.

It is currently believed that inactive tyrosine kinase c-Src in platelets binds to the cytoplasmic tail of the ß3 integrin subunit via its SH3 domain. Although a recent NMR study supports this contention, it is likely that such binding would be precluded in inactive c-Src because an auto-inhibitory linker physically occludes the ß3 tail binding site. Accordingly, we have re-examined c-Src binding to ß3 by immunoprecipitation as well as NMR spectroscopy. In unstimulated platelets, we detected little to no interaction between c-Src and ß3. Following platelet activation, however, c-Src was co-immunoprecipitated with ß3 in a time-dependent manner and underwent progressive activation as well. We then measured chemical shift perturbations in the (15)N-labeled SH3 domain induced by the C-terminal ß3 tail peptide NITYRGT and found that the peptide interacted with the SH3 domain RT-loop and surrounding residues. A control peptide whose last three residues where replaced with those of the ß1 cytoplasmic tail induced only small chemical shift perturbations on the opposite face of the SH3 domain. Next, to mimic inactive c-Src, we found that the canonical polyproline peptide RPLPPLP prevented binding of the ß3 peptide to the RT- loop. Under these conditions, the ß3 peptide induced chemical shift perturbations similar to the negative control. We conclude that the primary interaction of c-Src with the ß3 tail occurs in its activated state and at a site that overlaps with PPII binding site in its SH3 domain. Interactions of inactive c-Src with ß3 are weak and insensitive to ß3 tail mutations.

Crystallization kinetics of organic-inorganic trihalide perovskites and the role of the lead anion in crystal growth.

Methylammonium lead halide perovskite solar cells continue to excite the research community due to their rapidly increasing performance which, in large part, is due to improvements in film morphology. The next step in this progression is control of the crystal morphology which requires a better fundamental understanding of the crystal growth. In this study we use in situ X-ray scattering data to study isothermal transformations of perovskite films derived from chloride, iodide, nitrate, and acetate lead salts. Using established models we determine the activation energy for crystallization and find that it changes as a function of the lead salt. Further analysis enabled determination of the precursor composition and showed that the primary step in perovskite formation is removal of excess organic salt from the precursor. This understanding suggests that careful choice of the lead salt will aid in controlling crystal growth, leading to superior films and better performing solar cells.

Ultrasmooth organic-inorganic perovskite thin-film formation and crystallization for efficient planar heterojunction solar cells.

To date, there have been a plethora of reports on different means to fabricate organic-inorganic metal halide perovskite thin films; however, the inorganic starting materials have been limited to halide-based anions. Here we study the role of the anions in the perovskite solution and their influence upon perovskite crystal growth, film formation and device performance. We find that by using a non-halide lead source (lead acetate) instead of lead chloride or iodide, the perovskite crystal growth is much faster, which allows us to obtain ultrasmooth and almost pinhole-free perovskite films by a simple one-step solution coating with only a few minutes annealing. This synthesis leads to improved device performance in planar heterojunction architectures and answers a critical question as to the role of the anion and excess organic component during crystallization. Our work paves the way to tune the crystal growth kinetics by simple chemistry.

Thermally induced structural evolution and performance of mesoporous block copolymer-directed alumina perovskite solar cells.

Structure control in solution-processed hybrid perovskites is crucial to design and fabricate highly efficient solar cells. Here, we utilize in situ grazing incidence wide-angle X-ray scattering and scanning electron microscopy to investigate the structural evolution and film morphologies of methylammonium lead tri-iodide/chloride (CH3NH3PbI(3-x)Cl(x)) in mesoporous block copolymer derived alumina superstructures during thermal annealing. We show the CH3NH3PbI(3-x)Cl(x) material evolution to be characterized by three distinct structures: a crystalline precursor structure not described previously, a 3D perovskite structure, and a mixture of compounds resulting from degradation. Finally, we demonstrate how understanding the processing parameters provides the foundation needed for optimal perovskite film morphology and coverage, leading to enhanced block copolymer-directed perovskite solar cell performance.