Transition metal chalcogenides (TMCs) have gained worldwide interest owing to their outstanding renewable energy conversion capability. However, the poor mechanical flexibility of most existing TMCs limits their practical commercial applications. Herein, triggered by the recent and imperative synthesis of highly ductile α-Ag2S, an effective approach based on evolutionary algorithm and ab initio total-energy calculations for determining stable, ductile phases of bulk and two-dimensional Ag x Se1–x and Ag x Te1–x compounds was implemented. The calculations correctly reproduced the global minimum bulk stoichiometric P212121-Ag8Se4 and P21/c-Ag8Te4 structures. Recently reported metastable AgTe3 was also revealed but it lacks dynamical stability. Further single-layered screening unveiled two new monolayer P4/nmm-Ag4Se2 and C2–Ag8Te4 phases. Orthorhombic Ag8Se4 crystalline has a narrow, direct band gap of 0.26 eV that increases to 2.68 eV when transforms to tetragonal Ag4Se2 monolayer. Interestingly, metallic P21/c-Ag8Te4 changes to semiconductor when thinned down to monolayer, exhibiting a band gap of 1.60 eV. Present findings confirm their strong stability from mechanical and thermodynamic aspects, with reasonable Vickers hardness, bone-like Young’s modulus (E) and high machinability observed in bulk phases. Detailed analysis of the dielectric functions ε­(ω), absorption coefficient α­(ω), power conversion efficiency (PCE) and refractive index n(ω) of monolayers are reported for the first time. Fine theoretical PCE (SLME method ∼11–28%), relatively high n(0) (1.59–1.93), and sizable α­(ω) (104–105 cm–1) that spans the infrared to visible regions indicate their prospects in optoelectronics and photoluminescence applications. Effective strategies to improve the temperature dependent power factor (PF) and figure of merit (ZT) are illustrated, including optimizing the carrier concentration. With decreasing thickness, ZT of p-doped Ag–Se was found to rise from approximately 0.15–0.90 at 300 K, leading to a record high theoretical conversion efficiency of ∼12.0%. The results presented foreshadow their potential application in a hybrid device that combines the photovoltaic and thermoelectric technologies.

Herein we report the synthesis and characterization of electro-conductive chitosan–gelatin–agar (Cs-Gel-Agar) based PEDOT: PSS hydrogels for tissue engineering. Cs-Gel-Agar porous hydrogels with 0–2.0% (v/v) PEDOT: PSS were fabricated using a thermal reverse casting method where low melting agarose served as the pore template. Sample characterizations were performed by means of scanning electron microscopy (SEM), attenuated total reflectance–Fourier transform infrared spectroscopy (ATR–FTIR), X-ray diffraction analysis (XRD) and electrochemical impedance spectroscopy (EIS). Our results showed enhanced electrical conductivity of the cs-gel-agar hydrogels when mixed with DMSO-doped PEDOT: PSS wherein the optimum mixing ratio was observed at 1% (v/v) with a conductivity value of 3.35 × 10−4 S cm−1. However, increasing the PEDOT: PSS content up to 1.5 % (v/v) resulted in reduced conductivity to 3.28 × 10−4 S cm−1. We conducted in vitro stability tests on the porous hydrogels using phosphate-buffered saline (PBS) solution and investigated the hydrogels’ performances through physical observations and ATR–FTIR characterization. The present study provides promising preliminary data on the potential use of Cs-Gel-Agar-based PEDOT: PSS hydrogel for tissue engineering, and these, hence, warrant further investigation to assess their capability as biocompatible scaffolds.

Summary New, nontoxic and earth‐abundant materials for heat‐energy interconversion are urgently required to mitigate the over‐reliance on finite fossil fuels supply. Herein, using ab initio quantum mechanical calculations and Boltzmann theory, optimization of thermoelectric performances instable, mechanically robustCm‐SnSSe and P3m1‐SnSeS phases was performed. These phases exhibit an intrinsically low thermal conductivity of ~1.00 W m−1 K−1 at room temperature. Beyond 400 K, both phases display satisfactory thermoelectric performances, namely figure of merit ZT > 0.7 and power factor PF > 3.0 mW K−2 m−1. Better performances were obtained through holes doping at 1020 cm−3 concentration, where their ZT values reach 0.9 at 500 K and fluctuate minimally over broad temperature plateau, retaining the high PF over 3.0 mWK−2 m−1. Evolution into layered structure is also possible, with the calculated p‐type doping of P3m1‐SnSSe monolayer displaying decent ZT ~ 0.7 and very high PF > 6.0 mWK−2 m−1 beyond 300 K. In bulk form, the study specimens display superior machinability and mechanical properties, as evidenced by the approximately 8‐fold increase in their Vickers hardness when compared to PbTe and Bi2Te3 materials, while maintaining their plasticity characteristic. The computed E2D of 55.50 N m−1 is relatively low, which means Sn‐S‐Se alloy remains ductile when progressing to 2D state. Biaxial strain‐induced results show enhanced anharmonicity phonon scattering and thermopower increment, enabling maximum ZT ~ 1.0 and PF > 7.0 mW m−1 K−2 to be achieved in the appealing industrial waste heat akin 373 ≤ T ≤ 773 K range under 10% tensile strain.

This study outlines and developed a multilayer perceptron (MLP) neural network model for adolescent hypertension classification focusing on the use of simple anthropometric and sociodemographic data collected from a cross-sectional research study in Sarawak, Malaysia. Among the 2,461 data collected, 741 were hypertensive (30.1%) and 1720 were normal (69.9%). During the data gathering process, eleven anthropometric measurements and sociodemographic data were collected. The variable selection procedure in the methodology proposed selected five parameters: weight, weight-to-height ratio (WHtR), age, sex, and ethnicity, as the input of the network model. The developed MLP model with a single hidden layer of 50 hidden neurons managed to achieve a sensitivity of 0.41, specificity of 0.91, precision of 0.65, F -score of 0.50, accuracy of 0.76, and Area Under the Receiver Operating Characteristic (ROC) Curve (AUC) of 0.75 using the imbalanced data set. Analyzing the performance metrics obtained from the training, validation and testing data sets show that the developed network model is well-generalized. Using Bayes’ Theorem, an adolescent classified as hypertensive using this created model has a 66.2% likelihood of having hypertension in the Sarawak adolescent population, which has a hypertension prevalence of 30.1%. When the prevalence of hypertension in the Sarawak population was increased to 50%, the developed model could predict an adolescent having hypertension with an 82.0% chance, whereas when the prevalence of hypertension was reduced to 10%, the developed model could only predict true positive hypertension with a 33.6% chance. With the sensitivity of the model increasing to 65% and 90% while retaining a specificity of 91%, the true positivity of an adolescent being hypertension would be 75.7% and 81.2%, respectively, according to Bayes’ Theorem. The findings show that simple anthropometric measurements paired with sociodemographic data are feasible to be used to classify hypertension in adolescents using the developed MLP model in Sarawak adolescent population with modest hypertension prevalence. However, a model with higher sensitivity and specificity is required for better positive hypertension predictive value when the prevalence is low. We conclude that the developed classification model could serve as a quick and easy preliminary warning tool for screening high-risk adolescents of developing hypertension.

Structural and electronic properties of ternary clusters AlkTilNim, where k, l, and m are integers and k + l + m = 4, are investigated. These clusters are generated and studied by performing a two‐stage density functional theory (DFT) calculations using the Slater, Vosko, Wilks, and Nusair (SVWN) and Becke three‐parameter, Lee‐Yang‐Parr (B3LYP) functional exchange correlations. In the first stage, an unbiased global search algorithm coupled with a DFT code with a light exchange‐correlation and smaller basis sets are used to generate the lowest energy cluster structures. It is then followed by further optimization using another round of DFT calculation with heavy exchanged correlations and large basis set. Electronic properties of the structures obtained via the two‐stage procedure are then studied via DFT calculations. The results are illustrated in the form of ternary diagram. Our DFT calculations find that the stability of the cluster increases with the increase in the number of nickel atoms inside the clusters. Our findings provide new insight into the ternary metallic cluster through the structure, stability, chemical order, and electronic properties studies.

No abstract

Based on first-principles calculations, we propose a new two-dimensional (2D) van der Waal (vdW) heterostructure that can be used as a photocatalyst for water splitting. The heterostructure consists of vertically...

Crystalline ZnTeO thin films are promising materials for next generation photovoltaics. However, their structural stability and optical nonlinearity potential in bulk form have not been reported. Here, structural, electronic and optical properties of ZnTeO composites have been thoroughly studied using genetic algorithm and density functional theory (DFT). Energetically, mechanically and dynamically stable O-rich phases, namely Zn 2 Te 2 O 6 and ZnTeO 4 , were obtained. Ground-state properties such as lattice constants and simulated XRD were analyzed and compared to the experimental literature wherever possible. With a G 0 W 0 corrected band gap, these semiconducting phases display several desirable features, namely, Jahn-Teller distorted cations, hardness and shear anisotropy-induced optical nonlinearity that increase monotonically as O concentration elevates. Such trends appear to be consistent with that seen in the experimental study of ZnTeO thin film. It is observed that Zn-d, Te-p and O-p states have immense influence towards the electronic properties of these structures. Both phases exhibit steep elevation of absorption throughout the ultraviolet (UV) range, hitting peak value of ~5.0 × 10 5 cm −1 . Of particular interest, the non-centrosymmetric ZnTeO 4 has second harmonic generation coefficients (9.84 pm V −1 and 2.33 pm V −1 at static limit) greater than borates crystal and large birefringence that exceeds 0.08 in deep UV region, thus highlighting its potential pedigree as new optical materials in UV range.