Wide spectral photoresponse of layered platinum diselenide-based photodiodes

Platinum diselenide (PtSe2) is a group-10 transition metal dichalcogenide (TMD) that has unique electronic properties, in particular a semimetal-to-semiconductor transition when going from bulk to monolayer form. We report on vertical hybrid Schottky barrier diodes (SBDs) of two-dimensional (2D) PtSe2 thin films on crystalline n-type silicon. The diodes have been fabricated by transferring large-scale layered PtSe2 films, synthesized by thermally assisted conversion of predeposited Pt films at back-end-of-the-line CMOS compatible temperatures, onto SiO2/Si substrates. The diodes exhibit obvious rectifying behavior with a photoresponse under illumination. Spectral response analysis reveals a maximum responsivity of 490 mA/W at photon energies above the Si bandgap and relatively weak responsivity, in the range of 0.1–1.5 mA/W, at photon energies below the Si bandgap. In particular, the photoresponsivity of PtSe2 in infrared allows PtSe2 to be utilized as an absorber of infrared light with tunable sensitivity. The results of our study indicate that PtSe2 is a promising option for the development of infrared absorbers and detectors for optoelectronics applications with low-temperature processing conditions

Quantum confinement-induced semimetal-to-semiconductor evolution in large-area ultra-thin PtSe2 films grown at 400 °C

In this work, we present a comprehensive theoretical and experimental study of quantum confinement in layered platinum diselenide (PtSe2) films as a function of film thickness. Our electrical measurements, in combination with density functional theory calculations, show distinct layer-dependent semimetal-to-semiconductor evolution in PtSe2 films, and highlight the importance of including van der Waals interactions, Green’s function calibration, and screened Coulomb interactions in the determination of the thickness-dependent PtSe2 energy gap. Large-area PtSe2 films of varying thickness (2.5–6.5 nm) were formed at 400 °C by thermally assisted conversion of ultra-thin platinum films on Si/SiO2 substrates. The PtSe2 films exhibit p-type semiconducting behavior with hole mobility values up to 13 cm2/V·s. Metal-oxide-semiconductor field-effect transistors have been fabricated using the grown PtSe2 films and a gate field-controlled switching performance with an ION/IOFF ratio of >230 has been measured at room temperature for a 2.5–3 nm PtSe2 film, while the ratio drops to <2 for 5–6.5 nm-thick PtSe2 films, consistent with a semiconducting-to-semimetallic transition with increasing PtSe2 film thickness. These experimental observations indicate that the low-temperature growth of semimetallic or semiconducting PtSe2 could be integrated into the back-end-of-line of a silicon complementary metal-oxide-semiconductor process

Large-area growth of MoS2 at temperatures compatible with integrating back-end-of-line functionality

Direct growth of transition metal dichalcogenides over large areas within the back-end-of-line (BEOL) thermal budget limit of silicon integrated circuits is a significant challenge for 3D heterogeneous integration. In this work, we report on the growth of MoS2 films (~1-10 nm) on SiO2, amorphous-Al2O3, c-plane sapphire, and glass substrates achieved at low temperatures (350 C-550 C) by chemical vapor deposition in a manufacturing-compatible 300 mm atomic layer deposition reactor. We investigate the MoS2 films as a potential material solution for BEOL logic, memory and sensing applications. Hall-effect/4-point measurements indicate that the ~10 nm MoS2 films exhibit very low carrier concentrations (1014-1015 cm-3), high resistivity, and Hall mobility values of ~0.5-17 cm2 V-1 s-1, confirmed by transistor and resistor test device results. MoS2 grain boundaries and stoichiometric defects resulting from the low thermal budget growth, while detrimental to lateral transport, can be leveraged for the integration of memory and sensing functions. Vertical transport memristor structures (Au/MoS2/Au) incorporating ~3 nm thick MoS2 films grown at 550 C (~0.75 h) show memristive switching and a stable memory window of 105 with a retention time >104 s, between the high-low resistive states. The switching set and reset voltages in these memristors demonstrate a significant reduction compared to memristors fabricated from pristine, single-crystalline MoS2 at higher temperatures, thereby reducing the energy needed for operation. Furthermore, interdigitated electrode-based gas sensors fabricated on ~5 nm thick 550 C-grown (~1.25 h) MoS2 films show excellent selectivity and sub-ppm sensitivity to NO2 gas, with a notable self-recovery at room temperature. The demonstration of large-area MoS2 direct growth at and below the BEOL thermal budget limit, alongside memristive and gas sensing functionality, advances a key enabling technology objective in emerging materials and devices for 3D heterogeneous integration

MRI-derived g-ratio and lesion severity in newly diagnosed multiple sclerosis

Myelin loss is associated with axonal damage in established multiple sclerosis. This relationship is challenging to study in vivo in early disease. Here, we ask whether myelin loss is associated with axonal damage at diagnosis, by combining non-invasive neuroimaging and blood biomarkers. We performed quantitative microstructural MRI and single molecule ELISA plasma neurofilament measurement in 73 patients with newly diagnosed, immunotherapy naïve relapsing-remitting multiple sclerosis. Myelin integrity was evaluated using aggregate g-ratios, derived from magnetization transfer saturation (MTsat) and neurite orientation dispersion and density imaging (NODDI) diffusion data. We found significantly higher g-ratios within cerebral white matter lesions (suggesting myelin loss) compared with normal-appearing white matter (0.61 vs 0.57, difference 0.036, 95% CI 0.029 to 0.043, p &amp;lt; 0.001). Lesion volume (Spearman’s rho rs= 0.38, p &amp;lt; 0.001) and g-ratio (rs= 0.24 p &amp;lt; 0.05) correlated independently with plasma neurofilament. In patients with substantial lesion load (n = 38), those with higher g-ratio (defined as greater than median) were more likely to have abnormally elevated plasma neurofilament than those with normal g-ratio (defined as less than median) (11/23 [48%] versus 2/15 [13%] p &amp;lt; 0.05). These data suggest that, even at multiple sclerosis diagnosis, reduced myelin integrity is associated with axonal damage. MRI-derived g-ratio may provide useful additional information regarding lesion severity, and help to identify individuals with a high degree of axonal damage at disease onset. York, Martin et al. simultaneously measured g-ratio and plasma neurofilament in 73 relapsing-remitting multiple sclerosis patients at diagnosis using advanced MRI and single molecule ELISA. They demonstrate that g-ratio of cerebral white matter lesions varies at diagnosis, and show that high g-ratio of lesions is associated with elevated plasma neurofilament

Report from the Annual Conference of the British Society of Echocardiography, November 2017, Edinburgh International Conference Centre, Edinburgh

No abstract available

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Darkness on the edge of town: an exploratory study of heroin misuse in Athlone and Portlaoise.

This report was commissioned by the Midlands Regional Drugs Task Force. It examines, using quantitative and qulaitative methods, the extent and nature of heroin misuse in Athlone and Portlaoise towns. The report provides a range of short, medium and long term recommendations to policy makers and service providers