Reducing the dimensionality of three-dimensional hybrid metal halide perovskites can improve their optoelectronic properties. Here, we show that the third-order optical nonlinearity, n 2, of hybrid lead iodide perovskites is enhanced in the two-dimensional Ruddlesden-Popper series, (CH3(CH2)3NH3)2(CH3NH3)n-1PbnI3n+1 (n = 1–4), where the layer number (n) is engineered for bandgap tuning from E g = 1.60 eV (n = ∞; bulk) to 2.40 eV (n = 1). Despite the unfavorable relation, , strong quantum confinement causes these two-dimensional perovskites to exhibit four times stronger third harmonic generation at mid-infrared when compared with the three-dimensional counterpart, (CH3NH3)PbI3. Surprisingly, however, the impact of dimensional reduction on two-photon absorption, which is the Kramers-Kronig conjugate of n 2, is rather insignificant as demonstrated by broadband two-photon spectroscopy. The concomitant increase of bandgap and optical nonlinearity is truly remarkable in these novel perovskites, where the former increases the laser-induced damage threshold for high-power nonlinear optical applications.

Objective.: To report the high incidence of barotrauma in critically ill patients admitted to the intensive care unit (ICU) with coronavirus disease 2019 (COVID-19) and to discuss its implications. Design.: Retrospective cohort study. Setting.: ICU of an academic county hospital in Los Angeles, CA admitted from March 15-June 20, 2020. Patients.: 77 patients with COVID-19 pneumonia. 75 patients met inclusion criteria. Results.: 21% of patients with severe COVID-19 sustained barotrauma (33% of patients receiving IMV, 8% of patients receiving (NIV). There were no differences between the barotrauma and non-barotrauma groups regarding demographics, illness severity, or medications received, nor tidal volume or average/peak airway pressures in those receiving IMV. In the barotrauma group there was a greater proportion of patients receiving therapeutic anticoagulation (81% vs. 47%, p = 0.023) and ventilated using airway pressure release ventilation mode (13% vs. 0%, p = 0.043). Barotrauma was associated with increased likelihood of receiving a tracheostomy (OR 2.58 [0.23-4.9], p = 0.018]), longer median ICU length of stay (17 days vs. 7 days, p = 0.03), and longer median length of hospitalization (26 days vs. 14 days, p < 0.001). There was also a trend toward prolonged median duration of IMV (12.5 days vs 7 days, p = 0.13) and higher average mortality (56% vs 37%, p = 0.25). Conclusions.: Barotrauma is seen in 5-12% of patients with ARDS receiving IMV and is exceedingly rare in patients receiving NIV. We report a high incidence of barotrauma observed in critically ill patients with COVID-19 requiring either NIV or IMV. While there was a trend toward increased mortality in patients with barotrauma, this did not reach statistical significance. The increased incidence of barotrauma with COVID-19 may be a product of the pathophysiology of this disease state and a heightened inflammatory response causing rampant acute lung injury. Evidence-based medicine and lung-protective ventilation should remain the mainstay of treatment.

We conducted super-resolution light microscopy (LM) imaging of the distribution of ryanodine receptors (RyRs) and caveolin-3 (CAV3) in mouse ventricular myocytes. Quantitative analysis of data at the surface sarcolemma showed that 4.8% of RyR labeling colocalized with CAV3 whereas 3.5% of CAV3 was in areas with RyR labeling. These values increased to 9.2 and 9.0%, respectively, in the interior of myocytes where CAV3 was widely expressed in the t-system but reduced in regions associated with junctional couplings. Electron microscopic (EM) tomography independently showed only few couplings with caveolae and little evidence for caveolar shapes on the t-system. Unexpectedly, both super-resolution LM and three-dimensional EM data (including serial block-face scanning EM) revealed significant increases in local t-system diameters in many regions associated with junctions. We suggest that this regional specialization helps reduce ionic accumulation and depletion in t-system lumen during excitation-contraction coupling to ensure effective local Ca²⁺ release. Our data demonstrate that super-resolution LM and volume EM techniques complementarily enhance information on subcellular structure at the nanoscale.

A novel two-dimensional Ge-based hybrid perovskite is proposed for potential optoelectronic applications.

Organic–inorganic hybrid perovskites with a prototype formula MAPbI3 (MA = CH3NH3) have shown great promise in next-generation solar cells, yet a full understanding of their high power conversion efficiency relative to their inorganic counterparts has not been achieved. One of the most plausible arguments for their high efficiency is the ability of organic cations to form ferroelectric (FE) domains. By using first-principles calculations to examine the rotational behavior of MA cations in MAPbI3, here we show a relationship between the lattice structures and the FE dipole ordering of MA cations. It is found that the MA cations could form a spontaneous FE dipole ordering in tetragonal MAPbI3 at room temperature. The tendency of the FE formation is strongly related to the ratio of lattice parameters of MAPbI3. On the basis of the developed structure–ferroelectric-property relationship, we propose that a biaxial or uniaxial compressive strain and an anion doping with small halogen ions can further enhance the FE dipole ordering. These findings are in good agreement with the experimental discoveries that high-performance solar cells always incorporate mixed halide hybrid perovskites involving Br or Cl ions. This work may provide some guidelines for rational designs of highly efficient hybrid perovskite solar cells.

Background and Objective Patient portal use has increased over the last two decades in response to consumer demand and government regulation. Despite growing adoption, few guidelines exist to direct successful implementation and governance. We describe the policies and procedures that have governed over a decade of continuous My Health at Vanderbilt (MHAV) patient portal use. Methods We examined MHAV usage data between May 2007 and November 2017. We classified patient portal activity into eight functional categories: Appointment, Billing, Document Access, Genetics, Health Result, Immunization, Medication, and Messaging. We describe our operating policies and measure portal uptake, patient account activity, and function use over time. Results By the end of the study period, there were 375 517 registered accounts. Policies made MHAV available to competent adults and adolescents 13 and over. Patients signed up for a limited access account online, which could be upgraded to a full-access account after identity verification. Patients could assign proxy accounts to family and caregivers, which permitted nonpatient access to select MHAV functions. Laboratory and radiology results were accessible via MHAV. Results were classified into three groups based on sensitivity, which govern the length of delay before results appeared in MHAV. Discussion and Conclusion Patient portals offer significant opportunity to engage patients in their healthcare. However, there remains a need to understand how policies can promote uptake and use. We anticipate that other institutions can apply concepts from our policies to support meaningful patient portal engagement.

The hybrid organic-inorganic halide perovskites have emerged as one class of most promising light-harvesting materials for the next-generation solar cells because of their exceptional optoelectronic properties and low-temperature solution processability that allows for large-scale fabrication. [1-14] The hybrid halide perovskites are one class of semiconductors in a formula of ABX 3 that comprises a network of corner-sharing BX 6 octahedra. In this structure, A is an organic cation such as methylammonium (MA: CH 3 NH þ 3); B is a divalent metal cation such as Pb 2þ and Sn 2þ , located in the center; and X is a monovalent anion such as Cl À , Br À , and I À. These structural and compositional features determine their exceptional optoelectronic properties such as tunable bandgaps, [6-11] high absorption coefficient, [7-9,12-14] long carrier diffusion length [14-17] and lifetime, [6,17-23] low trap density, [16,17] and high carrier mobility. [7,8,14,17,24-27] Just in the past few years, the power conversion efficiency (PCE) of these halide perovskites solar cells at labscale testing has increased from 3.8% to 25.2% (in the perovskite/silicon tandem device). [28] Despite promising applications of halide perovskites in the photovoltaic industry, there are still several major challenges that inhibit their large-scale industrial applications. [29-32] These challenges include poor stability in ambient conditions, particularly in the moisture environment, and the demand for lead-free perovskites. For instance, ðMAÞPbI 3 will degrade into MAI and PbI 2 in ambient conditions in which the water molecules will facilitate the degradation process, sharply dropping perovskite thin film absorption in a matter of days. [33] Although encapsulation can mitigate the degradation from water molecules, [34] the hybrid perovskites were considered as intrinsically unstable in the long term due to unfavorable formation enthalpies. [35,36] 2D hybrid perovskites (2DHPs) offer a promising solution to overcome this instability issue. [37-47] The 2D nature refers to the layer structure of corner-sharing inorganic octahedra. These inorganic metal halide layers are interdigitated between bulky organic molecules such as butylammonium (BA: CH 3 ðCH 2 Þ 3 NH þ 3). The bulky organic molecules are bonded to the inorganic octahedra via hydrogen bonds, causing the large hydrophobic chain to orient away from the inorganic perovskite layers. This configuration forms organic bilayers that separate neighboring sheets, creating a repeating pattern of organic and inorganic layers that define the 2DHP crystal structure, see Figure 1. 2DHPs demonstrate some advantageous materials properties compared to the 3D hybrid perovskites (3DHPs), including high materials stability and robustness in the presence of water, [39,50] reasonable performance, and cheap solution processability. [37,51-54] Moreover, the interchangeability of the large organic cations and the control of layer dimensionality allow for greater tunability and flexibility of the physical and optoelect...

A rapid and highly sensitive miniaturized amperometric biosensor for the detection α-ketoglutarate (α-KG) based on a carbon fiber electrode (CFE) is presented. The biosensor is constructed by immobilizing the enzyme, glutamate dehydrogenase (GLUD) on the surface of single carbon fiber modified by co-deposition of ruthenium (Ru) and rhodium (Rh) nanoparticles. SEM and EDX shed useful insights into the morphology and composition of the modified microelectrode. The mixed Ru/Rh coating offers a greatly enhanced electrocatalytic activity towards the detection of β-nicotinamide adenine dinucleotide (NADH), with a substantial decrease in overpotential of ~400 mV compared to the unmodified CFE. It also imparts higher stability with minimal surface fouling, common to NADH oxidation. Further modification with the enzyme, GLUD leads to effective amperometric biosensing of α-KG through monitoring of the NADH consumption. A very rapid response to dynamic changes in the α-KG concentrations is observed with a response time of 6s. The current response is linear between 100 and 600 μM with a sensitivity of 42 μA M −1 and a detection limit of 20 μM. This proof of concept study indicates that the GLUD-Ru/Rh-CFE biosensor holds great promise for real-time electrochemical measurements of α-KG.