Ab initio Study of Misfit Dislocations at the SiC/Si(001) Interface

The high lattice mismatched SiC/Si(001) interface was investigated by means of combined classical and ab initio molecular dynamics. Among the several configurations analyzed, a dislocation network pinned at the interface was found to be the most efficient mechanism for strain relief. A detailed description of the dislocation core is given, and the related electronic properties are discussed for the most stable geometry: we found interface states localized in the gap that may be a source of failure of electronic devices

Application and validation of the notch master curve in medium and high strength structural steels

This paper applies and validates the Notch master curve in two ferritic steels with medium (steel S460M) and high (steel S690Q) strength. The Notch master curve is an engineering tool that allows the fracture resistance of notched ferritic steels operating within their corresponding ductile-to-brittle transition zone to be estimated. It combines the Master curve and the Theory of critical distances in order to take into account the temperature and the notch effect respectively, assuming that both effects are independent. The results, derived from 168 fracture tests on notched specimens, demonstrate the capability of the Notch master curve for the prediction of the fracture resistance of medium and high strength ferritic steels operating within their ductile-to-brittle transition zone and containing notches

Theoretical investigations of a highly mismatched interface: the case of SiC/Si(001)

Using first principles, classical potentials, and elasticity theory, we investigated the structure of a semiconductor/semiconductor interface with a high lattice mismatch, SiC/Si(001). Among several tested possible configurations, a heterostructure with (i) a misfit dislocation network pinned at the interface and (ii) reconstructed dislocation cores with a carbon substoichiometry is found to be the most stable one. The importance of the slab approximation in first-principles calculations is discussed and estimated by combining classical potential techniques and elasticity theory. For the most stable configuration, an estimate of the interface energy is given. Finally, the electronic structure is investigated and discussed in relation with the dislocation array structure. Interface states, localized in the heterostructure gap and located on dislocation cores, are identified

Water and lysozyme: Some results from the bending and stretching vibrational modes

The dynamic or glass transition in biomolecules is important to their functioning. Also essential is the transition between the protein native state and the unfolding process. To better understand these transitions, we use Fourier transform infrared spectroscopy to study the vibrational bending and stretching modes of hydrated lysozymes across a wide temperature range. We find that these transitions are triggered by the strong hydrogen bond coupling between the protein and hydration water. More precisely, we demonstrate that in both cases the water properties dominate the evolution of the system. We find that two characteristic temperatures are relevant: in the supercooled regime of confined water, the fragile-to-strong dynamic transition occurs at T[subscript L], and in the stable liquid phase, T* ≈ 315 ± 5 K characterizes the behavior of both isothermal compressibility K[subscript T] (T,P) and the coefficient of thermal expansion a[subscript P] (T,P)

Alternative Approaches in Development of Heterogeneous Titania-Based Photocatalyst

Three alternative approaches for the development of heterogeneous photocatalysts are comparatively evaluated, namely (i) the use of molecular imprinting concept for the development of heterogeneous catalysts employing rhodamine B as template and sol–gel as synthesis route; (ii) the impregnation of TiCl4 on mixed nano- and micro-metric silicas, followed by calcination; (iii) the use of industrial and academic chemical residues as source of potential photocatalyst species impregnated on supports. All tests were carried on with rhodamine B as target molecule. For comparative reasons, photocatalytic tests were carried out with commercial titania (P25). The solids were characterized by nitrogen porosimetry, small-angle X-ray scattering (SAXS), zeta potential (ZP), diffuse reflectance spectroscopy in the ultraviolet region (DRS-UV), diffuse reflectance infrared Fourier transmission spectroscopy (DRIFTS), and Rutherford backscattering spectrometry (RBS). The supported catalysts resulting from silica nanoparticles and residue of the petrochemical industry achieved higher percentage of the dye degradation under ultraviolet (68.0 and 66.8%, respectively) radiation. The industrial waste reached the highest photocatalytic activity under visible (61%) radiation, while the commercial P25 achieved 82.0and 12.3% for ultraviolet and visible radiation, respectively. The textural and structural characteristics of the supported catalyst prepared with fumed silica and petrochemical waste (SiPe), namely the low-energy bandgap (1.8 eV), large surface area (280 m2 g−1), high pore volume (1.9 cm3 g−1), and high zeta potential value (−36.4 mV), may have been responsible for their high activity

Subjective Cognitive Decline Higher Among Sexual and Gender Minorities in the United States, 2015–2018

Introduction: Subjective cognitive decline (SCD) represents self-reported problems with memory, a possible early sign of dementia. Little is known about SCD among sexual and gender minority (SGM) adults who identify as lesbian, gay, bisexual, and/or transgender or gender non-binary. Methods: Data were weighted to represent population estimates from 25 states’ 2015–2018 Behavioral Risk Factor Surveillance System to describe SCD in adults ≥ 45 years by SGM status. Logistic regression tested associations between demographic and health conditions. Results: SCD prevalence was higher in SGM (15.7%; 95% confidence interval [CI]:13.1–18.2) than in non-SGM adults (10.5%; 95% CI:10.1–10.9; P \u3c .0001). SGM adults with SCD were also more likely to report functional limitations due to SCD than non-SGM adults with SCD, 60.8% versus 47.8%, P =.0048. Differences in SCD by SGM status were attenuated after accounting for depression. Discussion: Higher prevalence of SCD in SGM adults highlights the importance of ensuring inclusive screenings, interventions, care services, and resources for SGM adults

Comparison of diagnostic accuracy of early screening for pre-eclampsia by NICE guidelines and a method combining maternal factors and biomarkers: results of SPREE

Objective To test the hypothesis that the performance of first-trimester screening for pre-eclampsia (PE) by a method that uses Bayes’ theorem to combine maternal factors with biomarkers is superior to that defined by current National Institute for Health and Care Excellence (NICE) guidelines. Methods This was a prospective multicenter study (screening program for pre-eclampsia (SPREE)) in seven National Health Service maternity hospitals in England, of women recruited between April and December 2016. Singleton pregnancies at 11–13weeks’ gestation had recording of maternal characteristics and medical history and measurements of mean arterial pressure (MAP), uterine artery pulsatility index (UtA-PI), serum placental growth factor (PlGF) and serum pregnancy-associated plasma protein-A (PAPP-A). The performance of screening for PE by the Bayes’ theorem-based method was compared with that of the NICE method. Primary comparison was detection rate (DR) using NICE method vs mini-combined test (maternal factors, MAP and PAPP-A) in the prediction of PE at any gestational age (all-PE) for the same screen-positive rate determined by the NICE method. Key secondary comparisons were DR of screening recommended by the NICE guidelines vs three Bayes’ theorem-based methods (maternal factors, MAP and PAPP-A; maternal factors, MAP and PlGF; and maternal factors, MAP, UtA-PI and PlGF) in the prediction of preterm PE, defined as that requiring delivery <37 weeks. Results All-PE developed in 473 (2.8%) of the 16 747 pregnancies and preterm PE developed in 142 (0.8%). The screen-positive rate by the NICE method was 10.3% and the DR for all-PE was 30.4% and for preterm PE it was 40.8%. Compliance with the NICE recommendation that women at high risk for PE should be treated with aspirin from the first trimester to the end of pregnancy was only 23%. The DR of the mini-combined test for all-PE was 42.5%, which was superior to that of the NICE method by 12.1% (95% CI, 7.9–16.2%). In screening for preterm PE by a combination of maternal factors, MAP and PlGF, the DR was 69.0%, which was superior to that of the NICE method by 28.2% (95% CI, 19.4–37.0%) and with the addition of UtA-PI the DR was 82.4%, which was higher than that of the NICE method by 41.6% (95% CI, 33.2–49.9%). Conclusions The performance of screening for PE as currently recommended by NICE guidelines is poor and compliance with these guidelines is low. The performance of screening is substantially improved by a method combining maternal factors with biomarkers

Unveiling oxygen vacancy impact on lizardite thermo and mechanical properties

Here, we performed a systematic DFT study assisted by the workflow framework SimStack for the mechanical and thermodynamic properties of the clay mineral lizardite in pristine and six different types of O vacancies configurations. In most cases, the defect caused a structural phase transition in the lizardite from the trigonal (pristine) to the triclinic phase. The results show that oxygen vacancies in lizardite significantly reduce the lattice thermal conductivity, accompanied by an elastic moduli reduction and an anisotropy index increase. Through the P–V relation, an increase in compressibility was evidenced for vacancy configurations. Except for the vacancy with the same crystalline structure as pristine lizardite, the sound velocities of the other vacancy configurations produce a decrease in these velocities, and it is essential to highlight high values for the Grüneisen parameter. We emphasize the great relevance of the punctual-defects introduction, such as O vacancies, in lizardite, since this microstructural design is responsible for the decrease of the lattice thermal conductivity in comparison with the pristine system by decreasing the heat transfer ability, turning lizardite into a promising candidate for thermoelectric materials

Spectrally narrow polarisation conversion in a slow-light photonic crystal waveguide

A narrow-band (3dB bandpass < 2 nm) transmission notch based on polarisation conversion within a SOI photonic crystal waveguide is demonstrated. Signal contrast between quasi- TE and TM eigenstates exceeding 40 dB is achieved. Further, multiple resonant wavelength coupling between the two eigenstates is also observed

Energy Consumption in Peer-to-Peer Protocols for Ubiquitous Devices

This paper studies energy consumption in peer-to-peer protocols in the context of file distribution among border devices and wireless sensors, which are limited in processing power and battery duration. Gnutella, Chord, CAN, Pastry, and Tapestry protocols were compared to the client-server approach insimulations using SimGrid and Triva, analyzing the energy cost of message exchanging. The peer-topeerprotocols presented less consumption to distribute a file among 10 devices, and the best results were achieved by the Chord protocol. The client-server architecture presented the worst results, as expected, due to the high concentration of load in a single server. Processing costs of the Gnutella protocol were comparedto the client-server’s, with very similar results.Keywords: peer-to-peer, ubiquitous computing, green computing