[en] In this work, density functional theory plane-wave pseudo potential method with generalized gradient approximation is used to investigate the elastic, mechanical, phonon and thermodynamic properties of LuAuPb and YAuPb compounds. The physical properties such as elastic constants, bulk modulus, shear modulus, Young's modulus, Poisson's ratio and shear anisotropy factor of both the compounds are calculated. The elastic properties of these compounds reveal that these compounds are mechanically stable. Further, the phonon dispersion curves prove that these compounds are also dynamically stable. The study of shear anisotropic factor gives purely anisotropic nature of these compounds. Pugh's and Frantsevich's ratio shows that both these compounds exhibit ductile nature. The sound velocities and Debye temperature of these compounds are also estimated from elastic constants. Using the slack equation, the lattice thermal conductivity of these compounds is also estimated. At room temperature, LuAuPb attains low thermal conductivity as compared to YAuPb. At 300 K, the calculated values of specific heat capacity per atom at constant volume for LuAuPb and YAuPb compounds are 24.37 Jmol⁻¹ K⁻¹ and 23.95 Jmol⁻¹ K⁻¹ respectively. This is the first quantitative theoretical estimation of these properties. - Highlights: • We found that LuAuPb and YAuPb are mechanically as well as dynamically stable. • The elastic properties of these compounds are calculated for the first time. • At 300 K, LuAuPb attains low lattice thermal conductivity as compared to YAuPb. • The Debye temperature of these compounds are estimated also.

[en] In this work, we have studied the Isoelectronic Sn-Ge substitution effect on electronic and thermoelectric properties of ZrNiSn compounds using the density functional theory and Boltzmann transport equations. The calculation shows that band gap decreases with doping and exhibit semiconductor nature. The negative value of Seebeck coefficient of all systems indicates that conduction is due to electrons. With increase in concentration of Ge, Seebeck coefficient decreases, while electrical conductivity and electronic thermal conductivity increases. At x=0.125, the maximum value of power is attained at 1200 K, which is equal to 9x10¹¹V²SK^-2ms^-1. (paper)

[en] Tensor network decompositions offer an efficient description of certain many-body states of a lattice system and are the basis of a wealth of numerical simulation algorithms. We discuss how to incorporate a global symmetry, given by a compact, completely reducible group G, in tensor network decompositions and algorithms. This is achieved by considering tensors that are invariant under the action of the group G. Each symmetric tensor decomposes into two types of tensors: degeneracy tensors, containing all the degrees of freedom, and structural tensors, which only depend on the symmetry group. In numerical calculations, the use of symmetric tensors ensures the preservation of the symmetry, allows selection of a specific symmetry sector, and significantly reduces computational costs. On the other hand, the resulting tensor network can be interpreted as a superposition of exponentially many spin networks. Spin networks are used extensively in loop quantum gravity, where they represent states of quantum geometry. Our work highlights their importance in the context of tensor network algorithms as well, thus setting the stage for cross-fertilization between these two areas of research.

[en] In this paper, we describe a refined matrix product representation for many-body states that are invariant under SU(2) transformations and use it to extend the time-evolving block decimation (TEBD) algorithm to the simulation of time evolution in the presence of an SU(2) symmetry. The resulting algorithm, when tested in a critical quantum spin chain, proved to be more efficient than the standard TEBD.

[en] The optimized geometry and electronic structure of an organic compound nickel phthalocyanine tetrasulfonic acid tetra sodium salt have been investigated using density functional theory. We have also optimized the structure of nickel phthalocyanine tetrasulfonic acid tetra sodium salt in dimethyl sulfoxide to study effects of solvent on the electronic structure and transitions. Experimentally, the electronic transitions have been studied using UV-VIS spectroscopic technique. It is observed that the electronic transitions obtained from the theoretical studies generally agree with the experiment.

[en] The Metal Phthalocyanine (MPc) have attracted much interest because of chemical and high thermal stability. Molecules forming a crystal of MPc are held together by weak attractive Vander Waals forces. Organic semiconductors have π conjugate bonds which allow electrons to move via π-electron cloud overlaps. Conduction mechanisms for organic semiconductor are mainly through tunneling; hopping between localized states, mobility gaps, and phonon assisted hopping. The photo conductivity of thin films of these complexes changes when exposed to oxidizing and reducing gases. Arrhenius plot is used to find the thermal activation energy in the intrinsic region and impurity scattering region. Arrhenius plotsare used to find the thermal activation energy.

[en] Thin films of copper phthalocyanine have been deposited on KBr and glass substrates by thermal evaporation method and characterized by the X-ray diffraction and optical absorption techniques. The observed X-ray pattern suggests the presence of α crystalline phase of copper phthalocyanine in the as-deposited thin films. Infrared spectra of thin films on the KBr pallet before and after exposure to the vapours of ammonia and methanol have been recorded in the wavenumber region of 400-1650 cm^-1. The observed infrared bands also confirm the α crystalline phase. On exposure, change in the intensity of some bands is observed. A new band at 1385 cm^-1, forbidden under ideal D_4h point group symmetry, is also observed in the spectra of exposed thin films. These changes in the spectra are interpreted in terms of the lowering of molecular symmetry from D_4h to C_4v. Axial ligation of the vapour molecules on fifth coordination site of the metal ion is responsible for lowering of the molecular symmetry

[en] Thin films of zinc phthalocyanine have been deposited on KBr and glass substrates by the thermal evaporation method and characterized by the x-ray diffraction, optical, infrared and Raman techniques. The observed x-ray diffraction and infrared absorption spectra of as-deposited thin films suggest the presence of an α crystalline phase. Infrared and Raman spectra of thin films after exposure to vapours of ammonia and methanol have also been recorded. Shifts in the position of some IR and Raman bands in the spectra of exposed films have been observed. Some bands also show changes in their intensity on exposure. Increased charge on the phthalocyanine ring and out-of-plane distortion of the core due to interaction between zinc phthalocyanine and vapour molecules involving the fifth coordination site of the central metal ion may be responsible for the band shifts. Changes in the intensity of bands are interpreted in terms of the lowering of molecular symmetry from D_4h to C_4v due to doming of the core. Molecular parameters and Mulliken atomic charges of zinc phthalocyanine and its complexes with methanol and ammonia have been calculated from density functional theory. The binding energy of the complexes have also been calculated. Calculated values of the energy for different complexes suggest that axially coordinated vapour molecules form the most stable complex. Calculated Mulliken atomic charges show net charge transfer from vapour molecules to the phthalocyanine ring for the most stable complex.

[en] Integrin receptors are heterodimeric transmembrane receptors with critical functions in cell adhesion and migration, cell cycle progression, differentiation, apoptosis, and phagocytosis of apoptotic cells. Integrins are activated by intracellular signaling that alter the binding affinity for extracellular ligands, so-called inside to outside signaling. A common element for integrin activation involves binding of the cytoskeletal protein talin, via its FERM domain, to a highly conserved NPxY motif in the β chain cytoplasmic tails, which is involved in long-range conformation changes to the extracellular domain that impinges on ligand affinity. When the human beta-5 (β5) integrin cDNA was expressed in αv positive, β5 and β3 negative hamster CS-1 cells, it promoted NPxY-dependent adhesion to VTN-coated surfaces, phosphorylation of FAK, and concomitantly, β5 integrin-EGFP protein was recruited into talin and paxillin-containing focal adhesions. Expression of a NPxY destabilizing β5 mutant (Y750A) abrogated adhesion and β5-Y750A-EGFP was excluded from focal adhesions at the tips of stress fibers. Surprisingly, expression of β5 Y750A integrin had a potent gain-of-function effect on apoptotic cell phagocytosis, and further, a β5-Y750A-EGFP fusion integrin readily bound MFG-E8-coated 10 μm diameter microspheres developed as apoptotic cell mimetics. The critical sequences in β5 integrin were mapped to a YEMAS motif just proximal to the NPxY motif. Our studies suggest that the phagocytic function of β5 integrin is regulated by an unconventional NPxY-talin-independent activation signal and argue for the existence of molecular switches in the β5 cytoplasmic tail for adhesion and phagocytosis

[en] Detection and discrimination of volatile organic compounds (VOCs) is important to provide a more realistic assessment of their potential implication in complex environments and medical diagnostics based on volatile biomarkers. Herein, chemiresistive sensors are fabricated using stacked MoS${}_2$ nanoflakes with defects and exposed-edge sites. The sensor is found to be extremely selective to triethylamine (TEA) over polar, non-polar VOCs and atmospheric gases. The sensor exhibits a sensitivity of 1.72% ppm${}^{-<!--\; ???\; -->1}$, fast response/recovery (19 s/39 s) to 100 ppm TEA at room temperature, low limit of detection (64 ppb), device reproducibility, humidity tolerance (RH 90%) and stability tested up to 60 days. The kinetic analysis of sensing curves reveals two discrete adsorption sites corresponding to edge and basal sites of interaction, with a higher rate constant of association and dissociation for TEA. The Density Functional Theory (DFT) studies support higher adsorption energy of TEA on MoS${}_2$ surface with respect to other volatile amines. The sensor demonstrates TEA recognition and composition estimation capability in a binary mixture of a similar class of VOCs using Machine Learning driven analysis with 95% accuracy. The ability to discriminate amines in binary mixture of other volatile amines paves the way for the advancement of next-generation devices in the field of disease diagnosis. (© 2024 Wiley‐VCH GmbH)