Band structure optimization of superconducting photonic crystals based on transmission spectrum calculation.

The design of photonic crystals using novel materials is of great significance for the construction of high-performance, next-generation photonic crystal devices. We propose a universal Band structure-Transmission optimization-Band structure method based on moving asymptotic (MMA) method, which can be widely applied to photonic crystal structures. In this paper, we use the method to optimize the band structure of high temperature superconducting photonic crystal, and obtain a wider photonic bandgap and better band flatness in a specific frequency band. This method avoids the disadvantages of traditional scanning methods such as low efficiency and high resource consumption, allows multi-parameter optimization, and improves the accuracy and effectiveness of band modulation based on the iterative process of numerical calculation. The study provides some insights for the design of novel wide-bandgap optical devices.

Investigation of Vacancy-Ordered Double Perovskite Halides A2Sn1-xTixY6 (A = K, Rb, Cs; Y = Cl, Br, I): Promising Materials for Photovoltaic Applications.

In the present study, the structural, mechanical, electronic and optical properties of all-inorganic vacancy-ordered double perovskites A2Sn1-xTixY6 (A = K, Rb, Cs; Y = Cl, Br, I) are explored by density functional theory. The structural and thermodynamic stabilities are confirmed by the tolerance factor and negative formation energy. Moreover, by doping Ti ions into vacancy-ordered double perovskite A2SnY6, the effect of Ti doping on the electronic and optical properties was investigated in detail. Then, according to the requirement of practical applications in photovoltaics, the optimal concentration of Ti ions and the most suitable halide element are determined to screen the right compositions. In addition, the mechanical, electronic and optical properties of the selected compositions are discussed, exhibiting the maximum optical absorption both in the visible and ultraviolet energy ranges; thus, the selected compositions can be considered as promising materials for application in solar photovoltaics. The results suggest a great potential of A2Sn1-xTixY6 (A = K, Rb, Cs; Y = Cl, Br, I) for further theoretical research as well as experimental research on the photovoltaic performance of stable and toxic-free perovskite solar cells.

Exploring the effect of C6H5-x/FxBr (x = 0-3) passivating agent on surface properties at different termination ends: first principles.

To prevent further decomposition of organic-inorganic hybrid perovskite by defects, in this work density functional theory was applied to explore the electronic properties, carrier surface mobility and theoretical photoelectric conversion efficiency (PCE) of passivating molecules with different fluorine atom content at the symmetric site of the benzene ring at different termination ends of MAPbI3, which shed light on the control of perovskite surface passivation by different element atoms in the same molecule. We found that the same molecule acts as a different passivation agent at different termination faces. Passivating molecules on the surface termination end by MAI play a Lewis acid role, with molecules with stronger dipole moments narrowing the band gap from the original 1.77 to 1.73 eV. The exciton binding energy of molecules with stronger dipole moments (0.187-0.292 meV) is significantly lower than that of MAPbI3 (0.332 meV), so the effective separation of interface electrons and holes can be realized. Bromopenta-fluorobenzene has a lower adsorption energy of -0.17 eV, which can stably adsorb on the surface of perovskite and increase visible light absorption. Ultimately, the theoretical PCE increased from 15.8% to 16.16%. In addition, on the surface terminated by PbI2, BrB with a strong dipole moment can provide electrons for Pb2+ and act as a Lewis base. At the surface end, it can form an ionic bond with Pb2+, while the antibonding molecular orbital characteristic is dominant, which increases the band gap from 1.76 to 1.87 eV. After increasing to 4-F-BrB, the fluorine atom has strong electronegativity and can easily bond with Pb2+. The conjugate π cycle intensifies the promotion of electron transfer, reducing the work function from 5.262 to 4.703 eV, reducing the effective electron and hole mass (0.514, 0.204 m0), and improving the photovoltaic performance. Finally, increasing the number of passivation molecules resulted in a decrease in the PCE from 15.93% to 14.75%.

Stent-Graft Fabrics Incorporating a Specific Corona Ready to Fenestrate.

In situ fenestration of endovascular stent-grafts has become a mainstream bailout technique to treat complex emergent aneurysms while maintaining native anatomical visceral and aortic arch blood supplies. Fabric tearing from creating the in situ fenestration using balloon angioplasty may extend beyond the intended diameter over time. Further tearing may result from the physiologic pulsatile motion at the branching site. A resultant endoleak at the fenestrated sites in stent-grafts could ultimately lead to re-pressurization of the aortic sac and, eventually, rupture. In an attempt to address this challenge, plain woven fabrics were designed. They hold a specific corona surrounding a square-shaped cluster with a plain weave fabric structure, a 2/2 twill, or a honeycomb. The corona was designed to stop potential further tearing of the fabric caused by the initial balloon angioplasty and stent or later post-implantation motion. The cluster within the corona was designed with relatively loose fabric structures (plain weave, 2/2 twill weave, and honeycomb) to facilitate the laser fenestration. Two commercial devices, Anaconda (Vascutek, Terumo Aortic) and Zenith TX2 (Cook), were selected as controls for comparison against this new design. All the specimens were characterized by morphology, thickness, and water permeability. The results demonstrated that all specimens with a low thickness and water permeability satisfied the requirements for a stent graft material that would be low profile and resistant to endoleaks. The in situ fenestrations were performed on all fabrics utilizing an Excimer laser followed by balloon angioplasty. The fabrics were further observed by light microscopy and scanning electron microscopy. The dimension of the fenestrated apertures was smaller than the balloon's diameter. The tearing was effectively confined within the corona. The clinical acceptability of this concept deserves additional bench testing and animal experimentation.

First-principles calculation of the optical properties of the YBa2Cu3O7-δ oxygen vacancies model.

We used first-principles methods to investigate how oxygen vacancy defects affect the optical properties of YBa2Cu3O7-δ (0 < δ < 1), a high-temperature superconductor with potential applications in optical detectors. We calculated the electronic structure of YBa2Cu3O7-δ with different amounts of oxygen vacancies at three different sites: Cu-O chains, CuO2 planes, and apical oxygens. The formation energy calculations support the formation of oxygen vacancies in the Cu-O chain at higher concentrations of vacancy defects, with a preference for alignment in the same chain. The presence of oxygen vacancies affects the optical absorption peak of YBa2Cu3O7-δ in different ways depending on their location and concentration. The optical absorption peaks in the visible range (1.6-3.2 eV) decrease in intensity and shift towards the infrared spectrum as oxygen vacancies increase. We demonstrate that oxygen vacancies can be used as a powerful tool to manipulate the optical response of YBa2Cu3O7-δ to different wavelengths in optical detector devices.

First-trimester surgical abortion practice in Canada in 2012.

OBJECTIVE: To evaluate practices among first-trimester surgical abortion facilities and providers in Canada in 2012 and examine the characteristics of the surgical abortion work force. DESIGN: Self-administered paper or electronic survey adapted from a survey previously fielded in the United States. SETTING: Canada. PARTICIPANTS: Facility administrators and physicians. MAIN OUTCOMES MEASURES: Descriptive statistics on reported first-trimester surgical abortion practice and provider demographic characteristics. RESULTS: Eighty-three percent of identified facilities (78 of 94) and 178 physicians responded. Of the respondents, 99% of facilities and 96% of physicians provided first-trimester surgical abortions. Responding facilities provided 68,154 first-trimester surgical abortions in 2012. This represented 96% of their reported total (combined medical and surgical) first-trimester abortions. More than half (55%) of responding facilities were community based, while 45% were hospital affiliated. Most physician providers were female (68%) and were family doctors (59%). Preoperatively, 96% of physicians routinely used ultrasound and 89% gave perioperative antibiotics. Almost half (48%) used manual vacuum aspiration, but less than 35% did so beyond 9 weeks after the last menstrual period. At most facilities, most procedures were performed under combined local anesthesia and intravenous sedation (73%); only 7% indicated deep sedation or general anesthesia were used exclusively. Postoperatively, 81% of physicians performed immediate tissue examination and 96% offered postabortion contraception on the same day as the abortion. Other assessed outcomes included medication regimens and cervical preparation, with a high degree of consistency among facilities and physicians. CONCLUSION: First-trimester surgical abortion providers are mostly family physicians and most are female. Practices across Canada were mostly uniform and followed evidence-based guidelines. Uptake of the most recent Canadian practice guidelines may help further standardize patient care and improve routine perioperative antibiotic use and immediate tissue examination.

Prolonged Use of Surgical Masks and Respirators Affects the Protection and Comfort for Healthcare Workers.

This study explored the ideal period for wearing masks to prevent the physiological and psychological problems associated with long-term face mask use during respiratory infections by healthcare workers. Breathing simulators, surgical masks (SM) and medical respirators (PM) were prepared for two to eight hours. Changes in the comfort of masks (facial skin temperature, breathing resistance, and moisture permeability) and protection (filtration efficiency, resistance to blood penetration, and colony count) were assessed. The results demonstrated that the masks offered efficient liquid-particle filtering even after eight hours of use. However, the number of bacterial colonies using PM and SM grew significantly after two and four hours, respectively. Concerning comfort, the inspiratory resistance of masks rose dramatically after two hours, whereas the moisture permeability declined considerably after four hours. In addition, skin temperature had a significant increase within two hours, which may result in facial discomfort. When conditions permitted, the hospital staff was instructed to replace their masks every two hours.

A promising type-II ß-AsP/g-C6N6 van der Waals heterostructure photocatalyst for water splitting: a first-principles study.

Photocatalytic water splitting, which can use abundant and clean solar energy, is friendly to the environment and consumes less energy. This work predicts the type-II ß-AsP/g-C6N6 van der Waals (vdW) heterostructure as a promising photocatalyst for water splitting using first-principles calculations. Compared with the g-C6N6 monolayer, the ß-AsP/g-C6N6 heterostructure not only can effectively separate photogenerated electron and hole pairs but also shows considerable light absorption and better photocatalyst performances. The optical absorption coefficient of the ß-AsP/g-C6N6 heterostructure has also extremely increased, more than ten times that of the g-C6N6 monolayer. The ß-AsP/g-C6N6 heterostructure with little compression (-2%) could be conducive to the hydrogen evolution reaction with a Gibbs free energy closer to zero (-0.46 eV) compared to monolayers. The oxygen evolution reaction has a low theoretical overpotential of 0.63 V. These results indicate that it exhibits favorable performances as a photocatalyst. This work predicts the possible application of the ß-AsP/g-C6N6 heterostructure as a photocatalyst and expands the scope of renewable energy devices.

Building Capacity for Community Pediatric Autism Diagnosis: A Systemic Review of Physician Training Programs.

OBJECTIVES: Training primary care providers to provide diagnostic assessments for autism spectrum disorder (ASD) decreases wait times and improves diagnostic access. Outcomes related to the quality of these assessments and the impacts on system capacity have not been systematically examined. This systematic review identifies and summarizes published studies that included ASD diagnostic training for primary care providers (PCPs) and aims to guide future training and evaluation methods. METHODS: Systematic searches of electronic databases, reference lists, and journals identified 6 studies that met 3 inclusion criteria: training for PCPs, community setting, and training outcome(s) reported. These studies were critically reviewed to characterize (1) study design, (2) training model, and (3) outcomes. RESULTS: All studies were either pre-post design or nonrandomized trials with a relatively small number of participants. There was considerable heterogeneity among studies regarding the training provided and the program evaluation process. The most evaluated outcomes were access to autism diagnosis and accuracy of diagnosis. CONCLUSION: Training PCPs to make ASD diagnoses can yield high diagnostic agreement with specialty teams' assessments and reduce diagnostic wait times. Current data are limited by small sample size, poor to fair quality study methodology, and heterogenous study designs and outcome evaluations. Evidence is insufficient to draw conclusions about the overall effects of training PCPs for ASD diagnostic assessments. Since further research is still needed, this review highlights which outcomes are relevant to consider when evaluating the quality of ASD assessments across the continuum of approaches.

In Vitro Laser Fenestration of Aortic Stent-Grafts: A Qualitative Analysis Under Scanning Electron Microscope.

In situ fenestration of stent-grafts allows patients with life threatening aortic pathologies to be amenable to emergent "off the shelf indications for use" percutaneous treatments as a bail out technique. Three types of aortic stent-grafts were subjected to laser fenestration in a physiological saline solution followed by balloon angioplasty using 8, 10 or 12 mm in diameter noncompliant balloons. The morphology and the size of fenestrations were observed under optical and scanning electron microscopy. The damage to the fabrics was analyzed and quantified. The creation of fenestrations was feasible in all devices, with varying degrees of fraying and/or tearing. The monofilament twill weave (Medtronic Valiant) tore in two directions (warp and weft) while the multifilament weave fenestrations showed more fraying (Anaconda Vascutek and Zenith TX2 Cook). The size and directions of tearing were more predictable with the 8 mm diameter balloon whereas the results obtained with the 10 and 12 mm diameter balloons were more unpredictable. The fenestrations were free of melting of the yarns and blackening of the filaments. The in situ fenestration is feasible but the observed damage to the fabric constructions must be carefully considered. This procedure must currently be limited to urgent and emergent life threatening cases because it is off indications for use for approved devices.