Nonlinear optical (NLO) crystals are the key component in solid‐state lasers. New second‐harmonic generation (SHG) effective halides, Cs3Pb2(CH3COO)2X5 (X=I, Br), have been rationally synthesized by ...introducing acetate groups into lead halide perovskites under moderate solvothermal conditions. Cs3Pb2(CH3COO)2X5 (X=I, Br) feature highly oriented anionic chains constructed by distorted PbX4O2 (X=I, Br) polyhedrons. Both the theoretical studies and the dipole moment calculations uncover that their SHG effects are mainly originated from the distorted PbX4O2 (X=I, Br) polyhedrons. Remarkably, Cs3Pb2(CH3COO)2I5 exhibits strong phase‐matching SHG response (8×KDP) and large birefringence (0.26@ 1064 nm). Moreover, Cs3Pb2(CH3COO)2X5 (X=I, Br) also possess high laser damage threshold (LDT) which are almost 27 and 41 times that of AgGaS2, respectively.
Cs3Pb2(CH3COO)2X5 (X=I, Br) featuring 1D highly oriented chain with strong second harmonic generation response are designed by rationally converting the idealized PbX6 octahedron into the distorted PbX4O2 polyhedron.
A novel niobium oxyiodate sulfate, Nb2O3(IO3)2 (SO4), was fabricated by a rational multi‐component design under moderate hydrothermal conditions. This multi‐component design is inspired by an ...interesting niobium oxysulfate reaction, which opens a new door for synthetic method to effectively introduce refractory metals such as Nb into crystal structures by hydrothermal synthesis. Nb2O3(IO3)2(SO4) features a cube‐like topological structure with a large phase‐matching second harmonic generation (SHG) response (6×KDP), a wide transparency window (0.38–8 μm), and a high laser damage threshold (LDT) (20×AgGaS2). It has the highest thermostability (stable up to 580 °C under air) among reported non‐centrosymmetric (NCS) iodates and sulfates and is stable in water and even concentrated H2SO4. Furthermore, Nb2O3(IO3)2(SO4) is a unique nonlinear optical (NLO) material among iodates and sulfates, because its SHG effect is mainly caused by the MO6 units rather than the IO3 or SO4 units, which is demonstrated by density functional theory (DFT) calculations.
Oh my‐obium! The synthesis of crystalline Nb2O3(IO3)2(SO4) under moderate hydrothermal conditions is reported. The highly thermostable crystal features a strong second‐harmonic‐generation response, a wide transparency window, and a high laser damage threshold.
A stretchable and multiple‐force‐sensitive electronic fabric based on stretchable coaxial sensor electrodes is fabricated for artificial‐skin application. This electronic fabric, with only one kind ...of sensor unit, can simultaneously map and quantify the mechanical stresses induced by normal pressure, lateral strain, and flexion.
The rapid and reversible lithiation/delithiation of silicon materials remains a challenging yet marvelous goal. Herein, harnessing the “nanoporous to compact” gradient design, a dual‐film consisting ...of flexible porous zincone and rigid compact TiO2 (zincone/TiO2) is controllably deposited onto a silicon electrode using molecular layer deposition and atomic layer deposition techniques. This dual‐film can tailor the stress and ionic diffusion kinetics for silicon anodes. That is, the elastic zincone acts as a buffer layer to dissipate inner stress through the deformation of pores, while the rigid TiO2 (≈5 nm) provides silicon particles a satisfying mechanical strength and protects the silicon from engulfing by the solid electrolyte interphase. The density functional theory and galvanostatic intermittent titration technique results indicate the fast Li+ diffusion kinetics in Si@zincone/TiO2 electrode, resulting in a high initial Coulombic efficiency of 81.9% and an advantageous rate capability of 1224 mAh g−1 at 4 A g−1. More importantly, a low capacity‐fading rate of only 0.051% per cycle can be achieved (discharge capacity of 753 mAh g−1 after 1000 cycles). Additionally, fractal theory verifies the Si@zincone/TiO2 undergoes gentle reversible evolutions during cycling with a box fractal dimension (DB) of 1.73.
A dual‐film consisting of flexible porous zincone and rigid compact TiO2 (zincone/TiO2) is controllably deposited onto a silicon electrode using molecular layer deposition and atomic layer deposition techniques.
To determine distribution of severe acute respiratory syndrome coronavirus 2 in hospital wards in Wuhan, China, we tested air and surface samples. Contamination was greater in intensive care units ...than general wards. Virus was widely distributed on floors, computer mice, trash cans, and sickbed handrails and was detected in air ≈4 m from patients.
The cellulose nanofibers of bacterial cellulose aerogel (BCA) are modified only on their surfaces using a trimethylsilylation reaction with trimethyichlorosilane in liquid phase followed by ...freeze-drying. The obtained hydrophobic bacterial cellulose aerogels (HBCAs) exhibit low density (≤6.77 mg/cm3), high surface area (≥169.1 m2/g), and high porosity (≈ 99.6%), which are nearly the same as those of BCA owing to the low degrees of substitution (≤0.132). Because the surface energy of cellulose nanofibers decreased and the three-dimensional web-like microstructure, which was comprised of ultrathin (20–80 nm) cellulose nanofibers, is maintained during the trimethylsilylation process, the HBCAs have hydrophobic and oleophilic properties (water/air contact angle as high as 146.5°) that endow them with excellent selectivity for oil adsorption from water. The HBCAs are able to collect a wide range of organic solvents and oils with absorption capacities up to 185 g/g, which depends on the density of the liquids. Hence, the HBCAs are wonderful candidates for oil absorbents to clean oil spills in the marine environment. This work provides a different way to multifunctionalize cellulose aerogel blocks in addition to chemical vapor deposition method.
The discovery of new nonlinear optical (NLO) crystals with excellent properties is in urgently demand because of their ability to generate coherent light. Herein, we report an unique NLO lead bromide ...formate, KCs2Pb2Br5 (HCOO)2, which has been synthesized by a mix‐solvothermal method. KCs2Pb2Br5(HCOO)2 exhibits strong phase‐matching second‐harmonic generation (SHG) response (6.5×KDP), large birefringence (0.16@ 1064 nm), and a wide transparent window in most visible light and mid‐IR region. Interestingly, KCs2Pb2Br5(HCOO)2 features a polar 3D lead‐bromide framework in which adjacent Pb−Br layers containing coplanar Pb6Br6 rings are not only parallel to each other, but also orient in the same direction. These oriented arrangements are responsible for the strong SHG response and large birefringence that are elucidated by both local dipole moment and theoretical calculations. This research provides a new strategy to explore subsequent NLO crystals.
KCs2Pb2Br5(HCOO)2 possessing strong second‐harmonic generation (SHG) response, large birefringence, and a wide transparent window in most visible light and mid‐IR region, has been obtained by the combination of HCOO groups and lead bromides. Interestingly, KCs2Pb2Br5(HCOO)2 features a polar 3D lead‐bromide framework in which adjacent Pb−Br layers containing coplanar Pb6Br6 rings not only parallel to each other, but also orient in the same direction. These oriented arrangements are responsible for the strong SHG response and large birefringence that are elucidated by both local dipole moment and theoretical calculations.
Introduction
We examined the coronavirus disease 2019 (COVID-19) pandemic impact on weekly trends in the billing of virtual and in-person physician visits in Ontario, Canada.
Methods
In this ...retrospective cohort study, physician billing records from Ontario were aggregated on a weekly basis for in-person and virtual visits from 3 January 2016 to 27 March 2021. For each type of visit, a segmented negative binomial regression analysis was performed to estimate the weekly pre-pandemic trend in billing volume per thousand adults (3 January 2016 to 14 March 2020), the immediate change in mean volume at the start of the pandemic, and additional change in weekly volume in the pandemic era (15 March 2020 to 27 March 2021).
Results
Before the start of the pandemic, the weekly volume of virtual visits per thousand adults was low with a 0.5% increase per week (rate ratio RR: 1.0053, 95% confidence interval CI: 1.0050–1.0056). A dramatic 65% reduction in in-person visits (RR: 0.35, 95% CI: 0.32–0.39) occurred at the start of the pandemic while virtual visits grew by 21-fold (RR: 21.3, 95% CI: 19.6–23.0). In the pandemic era, in-person visits rose by 1.4% per week (RR: 1.014, 95% CI: 1.011–1.017) but no change was observed for virtual visits (p-value = 0.31). Overall, we noted a 57.6% increase in total weekly physician visits volume after the start of the pandemic.
Discussion
These results are meaningful for virtual care reimbursement models. Future study needs to assess the quality of care and whether the increase in virtual care volume is cost-effective to society.
Nonlinear optical (NLO) crystals are widely applied in information technology, micro‐manufacturing and medical treatment. Herein, a new lead mixed halide with strong second‐harmonic generation (SHG) ...response, Cs3Pb2(CH3COO)2Br3I2, has been designed and rationally synthesized. Cs3Pb2(CH3COO)2Br3I2 represents the rare NLO crystal featuring that three different anions (I−, Br− and O2−) simultaneously coordinate the Pb(II) atom to form a severely distorted PbBr2I2O2 polyhedron with a large polarizability. Remarkably, Cs3Pb2(CH3COO)2Br3I2 not only exhibits a very strong phase‐matching SHG response of 9×KH2PO4 (KDP), but also possesses a large birefringence (0.27@1064 nm) and high laser damage threshold (LDT). The strong SHG effect of Cs3Pb2(CH3COO)2Br3I2 mainly originates from the oriented arrangement of Pb2Br3I2 chains. This study points out an effective strategy to develop new NLO crystals with strong SHG response.
A new lead mixed halide, Cs3Pb2(CH3COO)2Br3I2, has been designed and rationally synthesized. Cs3Pb2(CH3COO)2Br3I2 featuring that three different anions (I−, Br− and O2−) simultaneously coordinate the Pb(II) atom into a severely distorted PbBr2I2O2 polyhedron, exhibits a very strong phase‐matching second‐harmonic generation (SHG) response of 9×KH2PO4 (KDP) and a large birefringence (0.27@1064 nm). Systematic theoretical calculations demonstrate that the strong SHG effect of Cs3Pb2(CH3COO)2Br3I2 mainly originates from the oriented arrangement of Pb2Br3I2 chains.
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