Genotypic and phenotypic diversity of Bacillus spp. isolated from Freshwater Ecosystems

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Periodic review inventory policy for non-instantaneous deteriorating items with time dependent deterioration rate

The paper studies a periodic review inventory model with no shortages and different demand rates during pre- and post- deterioration periods . Deterioration of units start after a fixed time interval, and the deterioration rate is time dependent. The model determines the optimal reorder interval and the optimal order quantity so as to minimize the total cost per unit length of an inventory cycle. An extension of the model to include price discount has been further considered. Numerical examples are presented to illustrate the model and a sensitivity analysis is also reported

Low Thermal Conductivity and High Thermoelectric Performance in (GeTe)_{1–2<i>x</i>}(GeSe)_<i>x</i>(GeS)_<i>x</i>: Competition between Solid Solution and Phase Separation

GeTe and its derivatives constituting Pb-free elements have been well known as potential thermoelectric materials for the last five decades, which offer paramount technological importance. The main constraint in the way of optimizing thermoelectric performance of GeTe is the high lattice thermal conductivity (κ_lat). Herein, we demonstrate low κ_lat (∼0.7 W/m·K) and a significantly high thermoelectric figure of merit (ZT = 2.1 at 630 K) in the Sb-doped pseudoternary (GeTe)_{1–2<i>x</i>}(GeSe)_<i>x</i>(GeS)_<i>x</i> system by two-step strategies. The (GeTe)_{1–2<i>x</i>}(GeSe)_<i>x</i>(GeS)_<i>x</i> system provides an excellent podium to investigate competition between an entropy-driven solid solution and enthalpy-driven phase separation. In the first step, small concentrations of Se and S were substituted simultaneously in the position of Te in GeTe to reduce the κ_lat by phonon scattering due to mass fluctuations and point defects. When the Se/S concentration increases significantly, the system deviates from a solid solution, and phase separation of the GeS_1–<i>x</i>Se_<i>x</i> (5–20 μm) precipitates in the GeTe_1–<i>x</i>Se_<i>x</i> matrix occurs, which does not participate in phonon scattering. In the second stage, κ_lat of the optimized sample is further reduced to 0.7 W/m·K by Sb alloying and spark plasma sintering (SPS), which introduce additional phonon scattering centers such as excess solid solution point defects and grain boundaries. The low κ_lat in Sb-doped (GeTe)_{1–2<i>x</i>}(GeSe)_<i>x</i>(GeS)_<i>x</i> is attributed to phonon scattering by entropically driven solid solution point defects rather than conventional endotaxial nanostructuring. As a consequence, the SPS-processed Ge_0.9Sb_0.1Te_0.9Se_0.05S_0.05 sample exhibits a remarkably high ZT of 2.1 at 630 K, which is reproducible and stable over temperature cycles. Moreover, Sb-doped (GeTe)_{1–2<i>x</i>}(GeSe)_<i>x</i>(GeS)_<i>x</i> exhibits significantly higher Vickers microhardness (mechanical stability) compared to that of pristine GeTe

Evidence of Highly Anharmonic Soft Lattice Vibrations in a Zintl Rattler

Here, we present lattice dynamics associated with the local chemical bonding hierarchy in Zintl compound TlInTe$_2$, which cause intriguing phonon excitations and strongly suppress the lattice thermal conductivity to an ultralow value (0.46–0.31 W m$^{−1}$ K$^{−1}$) in the 300–673 K. We established an intrinsic rattling nature in TlInTe$_2$ by studying the local structure and phonon vibrations using synchrotron X‐ray pair distribution function (PDF) (100–503 K) and inelastic neutron scattering (INS) (5–450 K), respectively. We showed that while 1D chain of covalently bonded [InTe$_2$]$^{-n}_n$ transport heat with Debye type phonon excitation, ionically bonded Tl rattles with a frequency ca. 30 cm$^{−1}$ inside distorted Thompson cage formed by [InTe$_2$]$^{-n}_n$. This highly anharmonic Tl rattling causes strong phonon scattering and consequently phonon lifetime reduces to ultralow value of ca. 0.66(6) ps, resulting in ultralow thermal conductivity in TlInTe$_2$

Association of depression with disease duration, quality of life and adherence in Parkinson's disease: A cross sectional study

Background: Parkinson's disease (PD) is a progressive motor disorder often accompanied by non-motor symptoms such as depression. Objectives: The objective was to estimate the prevalence of depression in PD patients, and assess its association with disease duration, quality of life and adherence to treatment. Materials and Methods: This cross-sectional study was conducted in a tertiary care centre for patients diagnosed with PD. Depression was diagnosed using Hamilton Depression Rating Scale. The Chi-square test was used to assess the difference in proportions of depression in various types and severity of PD. Depression was also correlated with disease duration, quality of life (QOL) and adherence to treatment using the Pearson correlation test. A P value of <0.05 was considered statistically significant. Results: Among 51 patients, 20 (39.22%) patients were found to have depression. The mean duration of disease in depressed patients was significantly longer compared to that in non-depressed patients (7.99 ± 4.53 vs. 3.62 ± 2.23, P < 0.001), respectively. The non-depressed patients were better adherent to treatment (1.71 ± 1.5 vs. 0.56 ± 0.91). The quality of life of patients was significantly low for depressed patients (21.90 ± 6.91 vs. 13.16 ± 6.93, P < 0.001). Depression in Parkinson's patients was positively correlated with the duration of the disease (P-value <0.001); disease staging (P-value <0.001). Quality of life (QOL) had a strong correlation with depression (P-value <0.001) and Hoehn and Yahr (HY) staging (P-value <0.05). Conclusion: Depression was found in 39.22% of PD patients and was more significantly associated with disease duration, non-adherence to treatment and decreased quality of life

Evidence of Highly Anharmonic Soft Lattice Vibrations in a Zintl Rattler

Here, we present lattice dynamics associated with the local chemical bonding hierarchy in Zintl compound TlInTe$_2$, which cause intriguing phonon excitations and strongly suppress the lattice thermal conductivity to an ultralow value (0.46–0.31 W m$^{−1}$ K$^{−1}$) in the 300–673 K. We established an intrinsic rattling nature in TlInTe$_2$ by studying the local structure and phonon vibrations using synchrotron X-ray pair distribution function (PDF) (100–503 K) and inelastic neutron scattering (INS) (5–450 K), respectively. We showed that while 1D chain of covalently bonded $[InTe_2]_{n}^{-n}$ transport heat with Debye type phonon excitation, ionically bonded Tl rattles with a frequency ca. 30 cm$^{−1}$ inside distorted Thompson cage formed by $[InTe_2]_{n}^{-n}$. This highly anharmonic Tl rattling causes strong phonon scattering and consequently phonon lifetime reduces to ultralow value of ca. 0.66(6) ps, resulting in ultralow thermal conductivity in TlInTe$_2$

Evidence of Highly Anharmonic Soft Lattice Vibrations in a Zintl Rattler

Here, we present lattice dynamics associated with the local chemical bonding hierarchy in Zintl compound TlInTe$_2$, which cause intriguing phonon excitations and strongly suppress the lattice thermal conductivity to an ultralow value (0.46–0.31 W m$^{−1}$ K$^{−1}$) in the 300–673 K. We established an intrinsic rattling nature in TlInTe$_2$ by studying the local structure and phonon vibrations using synchrotron X‐ray pair distribution function (PDF) (100–503 K) and inelastic neutron scattering (INS) (5–450 K), respectively. We showed that while 1D chain of covalently bonded [InTe$_2$]$^{-n}_n$ transport heat with Debye type phonon excitation, ionically bonded Tl rattles with a frequency ca. 30 cm$^{−1}$ inside distorted Thompson cage formed by [InTe$_2$]$^{-n}_n$. This highly anharmonic Tl rattling causes strong phonon scattering and consequently phonon lifetime reduces to ultralow value of ca. 0.66(6) ps, resulting in ultralow thermal conductivity in TlInTe$_2$

Localized Vibrations of Bi Bilayer Leading to Ultralow Lattice Thermal Conductivity and High Thermoelectric Performance in Weak Topological Insulator <i>n-</i>Type BiSe

Realization of high thermoelectric performance in <i>n</i>-type semiconductors is of imperative need on account of the dearth of efficient <i>n</i>-type thermoelectric materials compared to the <i>p</i>-type counterpart. Moreover, development of efficient thermoelectric materials based on Te-free compounds is desirable because of the scarcity of Te in the Earth’s crust. Herein, we report the intrinsic ultralow thermal conductivity and high thermoelectric performance near room temperature in <i>n-</i>type BiSe, a Te-free solid, which recently has emerged as a weak topological insulator. BiSe possesses a layered structure consisting of a bismuth bilayer (Bi₂) sandwiched between two Bi₂Se₃ quintuple layers [Se–Bi–Se–Bi-Se], resembling natural heterostructure. High thermoelectric performance of BiSe is realized through the ultralow lattice thermal conductivity (κ_lat of ∼0.6 W/mK at 300 K), which is significantly lower than that of Bi₂Se₃ (κ_lat of ∼1.8 W/mK at 300 K), although both of them belong to the same layered homologous family (Bi₂)_<i>m</i>(Bi₂Se₃)_<i>n</i>. Phonon dispersion calculated from first-principles and the experimental low-temperature specific heat data indicate that soft localized vibrations of bismuth bilayer in BiSe are responsible for its ultralow κ_lat. These low energy optical phonon branches couple strongly with the heat carrying acoustic phonons, and consequently suppress the phonon mean free path leading to low κ_lat. Further optimization of thermoelectric properties of BiSe through Sb substitution and spark plasma sintering (SPS) results in high ZT ∼ 0.8 at 425 K along the pressing direction, which is indeed remarkable among Te-free <i>n-</i>type thermoelectric materials near room temperature

Ultrathin Free-Standing Nanosheets of Bi2O2Se: Room Temperature Ferroelectricity in Self-Assembled Charged Layered Heterostructure

Ultrathin ferroelectric semiconductors with high charge carrier mobility are much coveted systems for the advancement of various electronic and optoelectronic devices. However, in traditional oxide ferroelectric insulators, the ferroelectric transition temperature decreases drastically with decreasing material thickness and ceases to exist below certain critical thickness owing to depolarizing fields. Herein, we show the emergence of an ordered ferroelectric ground state in ultrathin (similar to 2 nm) single crystalline nanosheets of Bi2O2Se at room temperature. Free-standing ferroelectric nanosheets, in which oppositely charged alternating layers are self-assembled together by electrostatic interactions, are synthesized by a simple, rapid, and scalable wet chemical procedure at room temperature. The existence of ferroelectricity in Bi2O2Se nanosheets is confirmed by dielectric measurements and piezoresponse force spectroscopy. The spontaneous orthorhombic distortion in the ultrathin nanosheets breaks the local inversion symmetry, thereby resulting in ferroelectricity. The local structural distortion and the formation of spontaneous dipole moment were directly probed by atomic resolution scanning transmission electron microscopy and density functional theory calculations

The Weyl Semimetals MIrTe4 (M = Nb, Ta) as Efficient Catalysts for Dye-sensitized Hydrogen Evolution

The prevalent global energy crisis calls for searching viable pathways for generating green hydrogen as an alternative energy resource. Dye-sensitized photocatalytic water splitting is a feasible solution to produce green hydrogen. However, identifying suitable catalysts has been one of the bottlenecks in driving dye-sensitized photocatalysis efficiently. In this work, we report a new class of electrocatalysts based on the layered Weyl semimetals MIrTe4 (M = Nb, Ta) for the Eosin Y (EY)-sensitized hydrogen evolution reaction (HER) under visible light illumination. NbIrTe4 and TaIrTe4 exhibit HER activities of ~ 18000 and ~ 14000 mol.g-1, respectively after 10h of irradiation with visible light. Time-dependent UV-Vis spectroscopy and high-pressure liquid chromatography coupled with mass spectroscopy analysis shed light on the reaction dynamics and enable deeper understanding of the observed trend in hydrogen evolution rates for MIrTe4 materials. MIrTe4 (M = Nb, Ta) semimetals outperform related catalysts including transition metal dichalcogenides and other Weyl semimetals in terms of HER activity using EY as photosensitizer and triethanolamine as the sacrificial agent. We hypothesize that the topology-related band inversion in MIrTe4 Weyl semimetals promotes a high density of metal d-states near the Fermi level, driving their high catalytic performance. This study introduces a new class of layered Weyl semimetals as efficient catalysts, and provides perspectives for designing topology-enhanced catalysts