An electrodeposited inhomogeneous metal-insulator-semiconductor junction for efficient photoelectrochemical water oxidation.

The photoelectrochemical splitting of water into hydrogen and oxygen requires a semiconductor to absorb light and generate electron-hole pairs, and a catalyst to enhance the kinetics of electron transfer between the semiconductor and solution. A crucial question is how this catalyst affects the band bending in the semiconductor, and, therefore, the photovoltage of the cell. We introduce a simple and inexpensive electrodeposition method to produce an efficient n-Si/SiOx/Co/CoOOH photoanode for the photoelectrochemical oxidation of water to oxygen. The photoanode functions as a solid-state, metal-insulator-semiconductor photovoltaic cell with spatially non-uniform barrier heights in series with a low overpotential water-splitting electrochemical cell. The barrier height is a function of the Co coverage; it increases from 0.74 eV for a thick, continuous film to 0.91 eV for a thin, inhomogeneous film that has not reached coalescence. The larger barrier height leads to a 360 mV photovoltage enhancement relative to a solid-state Schottky barrier.

Disparities Among Limited English Proficient Patients in Colon Cancer Screening with Multi-target DNA Stool Test.

Racial and language minority groups in the U.S. are at a higher risk for morbidity and mortality from colorectal cancer (CRC), partially due to lower screening rates. This is a retrospective cohort study comparing successful multi-target stool DNA test (mt-sDNA) test completion among patients with limited English proficiency (LEP) and English proficient (EP) patients, from 2015 to 2018. Patients with LEP were frequency matched to EP patients by age at a 3:1 ratio. The percentage of mt-sDNA tests without useful results was 53% among patients with LEP compared to 29% among EP patients (p < 0.0001). The median number of days from order placement to test completion was 62.5 among patients with LEP compared to 33 for EP patients (p = 0.003). This study demonstrates a significant disparity in CRC screening completion using the mt-sDNA test among populations with LEP, which may widen existing disparities in CRC mortality.

Association Between SARS-CoV-2 Cycle Threshold Values and Clinical Outcomes in Patients With COVID-19: A Systematic Review and Meta-analysis.

Cycle threshold (CT) values are correlated with the amount of viral nucleic acid in a sample and may be obtained from some qualitative real-time polymerase chain reaction tests used for diagnosis of most patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, CT values cannot be directly compared across assays, and they must be interpreted with caution as they are influenced by sample type, timing of sample collection, and assay design. Presently, the correlation between CT values and clinical outcomes is not well understood. We conducted a systematic review and meta-analysis of published studies through April 19, 2021, that reported an association between CT values and hospitalization, disease severity, and mortality in patients ≥18 years old with SARS-CoV-2. A meta-analysis of 7 studies showed no significant difference in mean CT values between hospitalized and nonhospitalized patients. Among hospitalized patients, those with CT values <25 had a high risk of more severe disease and mortality than patients with CT values >30 (odds ratio [OR], 2.31; 95% CI, 1.70 to 3.13; and OR, 2.95; 95% CI, 2.19 to 3.96; respectively). The odds of increased disease severity and mortality were less pronounced in patients with CT values of 25-30 compared with >30.

Cell-based therapy to reduce mortality from COVID-19: Systematic review and meta-analysis of human studies on acute respiratory distress syndrome.

Severe cases of COVID-19 infection, often leading to death, have been associated with variants of acute respiratory distress syndrome (ARDS). Cell therapy with mesenchymal stromal cells (MSCs) is a potential treatment for COVID-19 ARDS based on preclinical and clinical studies supporting the concept that MSCs modulate the inflammatory and remodeling processes and restore alveolo-capillary barriers. The authors performed a systematic literature review and random-effects meta-analysis to determine the potential value of MSC therapy for treating COVID-19-infected patients with ARDS. Publications in all languages from 1990 to March 31, 2020 were reviewed, yielding 2691 studies, of which nine were included. MSCs were intravenously or intratracheally administered in 117 participants, who were followed for 14 days to 5 years. All MSCs were allogeneic from bone marrow, umbilical cord, menstrual blood, adipose tissue, or unreported sources. Combined mortality showed a favorable trend but did not reach statistical significance. No related serious adverse events were reported and mild adverse events resolved spontaneously. A trend was found of improved radiographic findings, pulmonary function (lung compliance, tidal volumes, PaO2 /FiO2 ratio, alveolo-capillary injury), and inflammatory biomarker levels. No comparisons were made between MSCs of different sources.

Nanometer-Thick Gold on Silicon as a Proxy for Single-Crystal Gold for the Electrodeposition of Epitaxial Cuprous Oxide Thin Films.

Single-crystal Au is an excellent substrate for electrochemical epitaxial growth due to its chemical inertness, but the high cost of bulk Au single crystals prohibits their use in practical applications. Here, we show that ultrathin epitaxial films of Au electrodeposited onto Si(111), Si(100), and Si(110) wafers can serve as an inexpensive proxy for bulk single-crystal Au for the deposition of epitaxial films of cuprous oxide (Cu2O). The Au films range in thickness from 7.7 nm for a film deposited for 5 min to 28.3 nm for a film deposited for 30 min. The film thicknesses are measured by low-angle X-ray reflectivity and X-ray Laue oscillations. High-resolution TEM shows that there is not an interfacial SiOx layer between the Si and Au. The Au films deposited on the Si(111) substrates are smoother and have lower mosaic spread than those deposited onto Si(100) and Si(110). The mosaic spread of the Au(111) layer on Si(111) is only 0.15° for a 28.3 nm thick film. Au films deposited onto degenerate Si(111) exhibit ohmic behavior, whereas Au films deposited onto n-type Si(111) with a resistivity of 1.15 Ω·cm are rectifying with a barrier height of 0.85 eV. The Au and the Cu2O follow the out-of-plane and in-plane orientations of the Si substrates, as determined by X-ray pole figures. The Au and Cu2O films deposited on Si(100) and Si(110) are both twinned. The films grown on Si(100) have twins with a [221] orientation, and the films grown on Si(110) have twins with a [411] orientation. An interface model is proposed for all Si orientations, in which the -24.9% mismatch for the Au/Si system is reduced to only +0.13% by a coincident site lattice in which 4 unit meshes of Au coincide with 3 unit meshes of Si. Although this study only considers the deposition of epitaxial Cu2O films on electrodeposited Au/Si, the thin Au films should serve as high-quality substrates for the deposition of a wide variety of epitaxial materials.

Electrodeposition of Epitaxial Lead Iodide and Conversion to Textured Methylammonium Lead Iodide Perovskite.

Applications for lead iodide, such as lasing, luminescence, radiation detection, and as a precursor for methylammonium lead iodide perovskite photovoltaic cells, require highly ordered crystalline thin films. Here, an electrochemical synthesis route is introduced that yields textured and epitaxial films of lead iodide at room temperature by reducing molecular iodine to iodide ions in the presence of lead ions. Lead iodide grows with a [0001] fiber texture on polycrystalline substrates such as fluorine-doped tin oxide. On single-crystal Au(100), Au(111), and Au(110) the out-of-plane orientation of lead iodide is also [0001], but the in-plane orientation is controlled by the single-crystal substrate. The epitaxial lead iodide on single-crystal gold is converted to textured methylammonium lead iodide perovskite with a preferred [110] orientation via methylammonium iodide vapor-assisted chemical transformation of the solid.

Preparation of Bi-Based Ternary Oxide Photoanodes BiVO4, Bi2WO6, and Bi2Mo3O12 Using Dendritic Bi Metal Electrodes.

The major limitation to investigating a variety of ternary oxides for use in solar energy conversion is the lack of synthesis methods to prepare them as high-quality electrodes. In this study, we demonstrate that Bi-based n-type ternary oxides, BiVO4, Bi2WO6, and Bi2Mo3O12, can be prepared as high-quality polycrystalline electrodes by mild chemical and thermal treatments of electrodeposited dendritic Bi films. The resulting oxide films have good coverage, adhesion, and electrical continuity, allowing for facile and accurate evaluation of these compounds for use in solar water oxidation. In particular, the BiVO4 electrode retained the porosity and nanocrystallinity of the original dendritic Bi film. This feature increased the electron-hole separation yield, making this compound more favorable for use as a photoanode in a photoelectrochemical cell.