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Summary: 2D Ruddlesden‐Popper (RP) perovskites (R‐NH3)2An−1BnX3n+1 with tailorable photovoltaic features of low toxicity, reduced dimensionality, and defect tolerance hold promise to overcome the main constraints of perovskite solar cells (PSCs). A systematic investigation of the structural and electronic properties of pure and mixed (R‐NH3)2Pb1−xGexI4 systems was performed with and without spin‐orbit coupling (SOC), by using density functional theory (DFT). The organic spacer cations (R‐NH3+)2 of methylammonium (MA‐CH3NH3+) and Phenylethyl ammonium (PEA‐C6H5[CH2]2NH3+) with x = 0.0, 0.25, 0.50, 0.75, 1.0, resulted in the compositionally modified 32‐permutations by systematically substituting the inorganic cations. Short‐range ordering has categorized all studied compositions of (R‐NH3)2Pb0.50Ge0.50I4 into column and battenberg schemes depending on the Ge defect site. The competing effects of octahedral tilting and lattice distortion with bandgap bowing and SOC, across Pb‐Ge compositional systems, provide a systematic strategy to tune bandgaps. By controlling the cations' composition, these mixed 2D‐perovskites outlined the strategy to achieve the desired bandgap and band positions. A rational design approach of low dimensional perovskites was adopted to tune the electronic properties through the spacer and inorganic cation engineering. Our findings expose the scope of monolayer‐based systems as an ideal choice of absorber for the bottom sub‐cell in all‐perovskites 2D‐3D tandem solar cell, harvesting light from visible (2.4 eV) up to infrared (1.2 eV) in the solar spectrum with features of defect tolerance, quantum and dielectric confinement, low bandgap, low effective masses, and high mobility. [ABSTRACT FROM AUTHOR]

Half-Heusler alloys are anticipated to impact real applications for instance industrial waste heat recovery due to their high thermoelectric (TE) properties, good thermal stability, and excellent elastic properties. The state-of-the-art density functional theory (DFT) is used to calculate the electronic structure, magnetic, elastic, thermodynamic, and transport properties of the cubic CrMnS half-Heusler (HH) alloy. Ferromagnetic (FM) configuration is found to be energetically most favorable than non-magnetic (NM) and antiferromagnetic (AFM) states for the HH CrMnS alloy. The spin‐resolved band structure of HH CrMnS prevails its half‐metallicity at the Fermi level with a total magnetic moment of 1 μ B . The cohesive and formation energy analysis along with the phonon dispersion curve indicate that HH CrMnS is a chemically, thermodynamically, and vibrationally stable compound. Elastic properties for the studied compound show its mechanical stability, anisotropic & brittle nature with high hardness, and Debye temperature of 410 K. Thermodynamic parameters are also calculated which depict the stability of the studied alloy at varied pressure and temperature. Furthermore, thermoelectric (TE) properties indicate that HH CrMnS alloy has a maximum value of power factor (PF) equal to 3.3 × 1011 WK−2 m−1 s−1 at 1000 K and ZT value of 0.72 at 600 K. The vibrational and mechanical stability, higher bandgap (~ 0.96 eV) and 100% spin-polarization demonstrate that HH CrMnS can be a potential alloy for TE and spintronic applications. [ABSTRACT FROM AUTHOR]

Summary: We present a comparative study on the structural, electronic, elastic, and thermoelectric properties of the cubic inverse‐perovskites A3OX (where A = Li, Na, K and X = Cl, Br, I) by density functional theory (DFT). The cohesive, formation, and elastic properties analysis indicates that all studied materials are chemically, thermodynamically, and mechanically stable. Electronic properties reveal that all the inverse A3OX perovskite are direct bandgap semiconductors except Li3OCl and Li3OBr with ionic nature which is confirmed by electron localization function (ELF) analysis. We have also calculated Debye temperature (ΘD) and Grüneisen parameter (γ) to determine the lattice thermal conductivity for all the A3OX materials. Furthermore, thermoelectric (TE) properties are explored by calculating the Seebeck coefficient (S), electronic thermal conductivity, power factor (PF), electrical conductivity (σ/τ), lattice thermal conductivity, and ZT value. Our investigated A3OX inverse‐perovskites provide a fertile base that can improve the overall TE performance for TE applications and green energy production. [ABSTRACT FROM AUTHOR]

Intercalation of large organic spacer cations with inorganic layers of octahedral metal halide cages in 2D-Ruddlesden–Popper (RP) monolayer perovskites (R–NH3) 2 A n −1 B n X 3n+1 by using a rational design approach has shown structural versatility and energetic stability. A systematic theoretical investigation of the structural, electronic, and mechanical properties was conducted with and without spin-orbit coupling (SOC) under the influence of a range of organic monovalent spacer cations [R–NH 3 ] + with different inorganic halide anions. This resulted in 12 compositions. Lattice distortion and octahedral tilting provided gradient band gaps that displayed a good linear relationship with equatorial Sn–X–Sn angles in debt of larger halide anions. By fixing halide ions, larger spacer cations reduce the band gap further. The halides function as acceptors, whereas Sn and N function as donors. Intermingled N -atoms of spacer cations incorporate additional charges to axial halide ions of [SnX 6 ] 4- with state-of-the-art features of defect tolerance, quantum and dielectric confinement, low effective masses, and high mobility. Graphical representation of compositionally modified 2D-Ruddlesden – Popper (RP) monolayer perovskites (R–NH 3) 2 An −1 B n X 3n+1 configured into 12 structures by systematically substituting the inorganic anions (X = Cl, Br, I) in [SnX 6 ]4- octahedra and monovalent organic spacer cations [R–NH 3 ]+, including butyl-ammonium (C 8 H 24 N 2), hexyl-ammonium (C 12 H 32 N 2), phenyl-ammonium (C 16 H 24 N 2), and octyl-ammonium (C 16 H 40 N 2). [Display omitted] • Density functional theory (DFT) validates experimentally designed structures. • New 2D semiconductor perovskites are designed with appropriate band gaps closer to the optimal band gap of solar cells. • The degree of structural stability of 2D-perovskites gets improved with smaller spacer cations and halide anions. • The band gap of 2D-perovskites gets reduced in the order of larger A-cations and X-halide anions. • The octahedral tilting by varied halide anions and lattice compression by spacer cations tune the properties. [ABSTRACT FROM AUTHOR]

First principles-based DFT investigation of strain-influenced 2D-monolayer Ruddlesden-Popper (RP) Phenyl-ammonium Tin Iodide (PH 2 SnI 4) perovskite under biaxial strain ranging from ±2%, ±4%, ±6%, to ±8%) was performed. The compressive (-ve) strain caused band gap reduction while tensile strain produced structural elongation with a higher band gap. The competing effects of structural distortion and octahedral tilting offered a band gap tuning, with compressive-strain (Eg 1), zero-strain (Eg 2), and tensile-strain (Eg 3) following the order of Eg 1 < Eg 2 < Eg 3. Unstrained band gap (1.329 eV) gets reduced to 1.262 eV and 1.235, under compressive strain (-ε xx) of −6% and −8%, respectively. However, tensile strains (+ε xx) of +6% and +8% increased the band gap to 1.331 eV and 1.367 eV, respectively. [Display omitted] • A metallic to semiconductor transition is observed under the effect of strain and spin orbit coupling. • All structures are found mechanically stable, with compression offering enhanced stabilization. • Strain induced states are found defects tolerant states contributing to band edges. • Under compressive forces, average bond lengths (Å) and polyhedral volume (Å3) shrink with a higher in-plane tilting of peripheral octahedrons, thus offering a larger bond angle variance (deg.2) of corner octahedrons than the central one. • For compressive-strained configurations, the smaller exciton binding energy corresponds to easily separated electron − hole pairs. • The high absorption coefficient, low reflectivity, and high optical conductivity make these materials suitable for photovoltaic and other optoelectronic device applications. Based on RP perovskites, we put 2%, 4%, 6%, and 8% biaxial strains on 2D monolayers of phenyl-ammonium tin iodide (PH 2 SnI 4) perovskites. Density functional theory (DFT) is used to study the structural distortion, octahedral tilting, band gap tuning, Bader charge analysis, and mechanical stability of the resulting configurations. Band gaps under the effects of compressive strain (Eg1), zero strain (Eg2), and tensile strain (Eg3) follow a decreasing order of Eg 1 (1.262 eV) < Eg 2 (1.329 eV) < Eg 3 (1.331 eV) for 6%-strain. The absence of trap states in energy band gaps and dominant cation and anion contributions at conduction and valence band edges supports the defect tolerance. All the structures analyzed are mechanically stable. The covalently bonded structures are ductile/brittle under tensile/compressive strain, with a prominent stretching mode. Strain improves the optical performance with dielectric constant increased (red-shifted) under compressive strain and reduced (blue-shifted) under compressive strain. [ABSTRACT FROM AUTHOR]

Half-Heusler (HH) alloys are a well-known and extensively researched family of thermoelectric (TE), magnetic, and spintronic materials. Doping may significantly increase the thermoelectric conversion efficiency of these materials; nevertheless, practical applications remain far. As a result, the hunt for superior parent TE alloys is critical. Using extensive first-principles density functional calculations, we predicted a novel class of vanadium-based four HH VXTe alloys, where X is one of the four elements: Cr, Mn, Fe, and Co. Their TE properties, as well as their mechanical, magnetic, electrical, and structural stability, have been studied in depth. Their mechanical and thermodynamic stability is confirmed using the predicted elastic constants, formation and cohesive energies, and phonon spectra. A comprehensive analysis of elastic constants and moduli demonstrates that HH VXTe alloys possess elastic anisotropy with reasonably good machinability, higher melting and Debye temperatures, mixed bonding characteristics with ionic and covalent contributions, and brittle nature, except for VCoTe, which is ductile. We find that the ground state of HH VCrTe and VFeTe is ferrimagnetic, while HH VCoTe is ferromagnetic and HH VMnTe is non-magnetic. Three VXTe (X = Cr, Fe, & Co) alloys demonstrated half-metallicity with 100% spin-polarization, whereas HH VMnTe is an 18-electron indirect semiconductor. In the studied HH VXTe alloys, most of the heat flow is caused by the phonon-group velocity of the acoustic phonons. Further studies on the relationship between carrier concentration and temperature dependence of TE properties reveal that the high ZT ∼1.2 at 1000 K of the pristine HH VMnTe alloy is obtained due to its high-power factor of 249.4 × 10 12 W m − 1 K − 2 and this value is greater than the values of some known pristine and doped HH TE materials. Our findings pave the way for further investigation into the HH VXTe alloys in the quest for improved TE and spintronic materials for use in domains that necessitate high thermoelectricity and spintronic performance. [ABSTRACT FROM AUTHOR]

Objectives: The objective of this study was to assess the knowledge of acute coronary syndrome (ACS) patients regarding revascularization procedure following coronary angiography at a tertiary care cardiac center of Karachi, Pakistan. Methodology: This descriptive cross-sectional study included newly diagnosed adult patients of ACS admitted to the inpatients department. However, patients with the diagnosis of STsegment elevation myocardial infarction (STEMI) undergone primary PCI were excluded. Patients' knowledge level was assessed by interviewing patients with questionnaire consisted of a total of 10 multiple choice questions. Patients' response against each of the question was verified by the patient's hospital record file and categorized as correct or incorrect. Patients with =70% correct responses (7 out of 10) were categorized to have had sufficient knowledge about revascularization. Results: A total of 130 patients were included with mean age of patients was 57.42±18.43 years and majority of patients, 86.2%(112), were males. Sufficient knowledge regarding revascularization procedure was observed in only 37.7%(49) patients. Male patients had significantly higher frequency of sufficient knowledge than female patients (40.2%(45/112) vs. 22.2%(4/18); p<0.001). Similarly, knowledge level was significantly higher among urban resident than rural residents with frequency of 41.1%(39/95) vs. 28.6%(10/35); p=0.009. Likewise educational status (p<0.030) and age of the patients (p=0.003) were also found to be a significant factors associated with sufficient knowledge. Conclusion: Majority of patients had insufficient knowledge regarding acute coronary syndrome and its revascularization options among ACS patients. It is the need of hour to define strategies to so educate and counsel these patients properly. [ABSTRACT FROM AUTHOR]

This study reports a systematic density functional theory-based analysis on electronic properties of individual doping and codoping of Ti and Ce into GaN. In the case of codoped GaN, the placement of Ti and Ce at nearest neighbour sites appeared as the most stable configuration. The unoccupied states in the case of individual doped material are observed to become occupied after codoping, and a metal-to-metal charge transfer of the Ti-N-Ce character is observed in the material. The interaction between dopants suggests 4f-5d-CB hybridization that opens the way to the exploitation of novel luminescence phenomena. A model showing charge transfer and interaction between the dopants is proposed. [ABSTRACT FROM AUTHOR]

Diagnosis of tumor and definition of tumor borders intraoperatively using fast histopathology is often not sufficiently informative primarily due to tissue architecture alteration during sample preparation step. Confocal laser microscopy (CLE) provides microscopic information of tissue in real-time on cellular and subcellular levels, where tissue characterization is possible. One major challenge is to categorize these images reliably during the surgery as quickly as possible. To address this, we propose an automated tissue differentiation algorithm based on the machine learning concept. During a training phase, a large number of image frames with known tissue types are analyzed and the most discriminant image-based signatures for various tissue types are identified. During the procedure, the algorithm uses the learnt image features to assign a proper tissue type to the acquired image frame. We have verified this method on the example of two types of brain tumors: glioblastoma and meningioma. The algorithm was trained using 117 image sequences containing over 27 thousand images captured from more than 20 patients. We achieved an average cross validation accuracy of better than 83%. We believe this algorithm could be a useful component to an intraoperative pathology system for guiding the resection procedure based on cellular level information. [ABSTRACT FROM AUTHOR]