Coupling-Induced Dynamic Off-Centering of Cu Drives High Thermoelectric Performance in TlCuS.

Seeking new and efficient thermoelectric materials requires a detailed comprehension of chemical bonding and structure in solids at microscopic levels, which dictates their intriguing physical and chemical properties. Herein, we investigate the influence of local structural distortion on the thermoelectric properties of TlCuS, a layered metal sulfide featuring edge-shared Cu-S tetrahedra within CuS layers. While powder X-ray diffraction suggests average crystallographic symmetry with no distortion in CuS tetrahedra, the synchrotron X-ray pair distribution function experiment exposes concealed local symmetry breaking, with dynamic off-centering distortions of the CuS tetrahedra.

Electrically and magnetically readable memory with a graphene/1T-CrTe heterostructure: anomalous Hall transistor.

Using first-principles theoretical analysis, we demonstrate the spin-polarized anomalous Hall conductivity (AHC) response of a 2D vdW heterostructure of graphene and ferromagnetic CrTe that can be controlled with a perpendicular electric field . The origins of AHC and linear magnetoelectric responses are traced to (a) the transfer of electronic charge from graphene to ferromagnetic CrTe causing an out-of-plane electric polarization = 1.69 μC cm and (b) the crystal field and spin-split Dirac points of graphene.

Spontaneous weathering of natural minerals in charged water microdroplets forms nanomaterials.

In this work, we show that particles of common minerals break down spontaneously to form nanoparticles in charged water microdroplets within milliseconds. We transformed micron-sized natural minerals like quartz and ruby into 5- to 10-nanometer particles when integrated into aqueous microdroplets generated via electrospray. We deposited the droplets on a substrate, which allowed nanoparticle characterization.

Prehospital Cervical Spine (C-spine) Stabilization and Airway Management in a Trauma Patient: A Review.

Severe traumatic damage to the brain-to-body signaling bundle that results in bruising and a partial or total tear of the spinal cord is known as a spinal cord injury (SCI). SCI may develop at the time of an event or after. It can also develop while handling the patient and can worsen during the transportation of the patient.

Interplay of missed opportunity for vaccination and poor response to the vaccine led to measles outbreak in a slum area of Eastern Mumbai, India.

In the third week of September 2022, an outbreak of measles was reported from a slum in Eastern Mumbai, India. We sought to investigate whether failure to vaccinate or vaccine failure was the cause. We constructed an epidemic curve, drew a spot map, and calculated the attack rate and case-fatality ratio.

Electrostatically tunable interaction of CO with MgO surfaces and chemical switching: first-principles theory.

Electric field-assisted CO capture using solid adsorbents based on basic oxides can immensely reduce the required energy consumption compared to the conventional processes of temperature or pressure swing adsorption. In this work, we present first-principles density functional theoretical calculations to investigate the effects of an applied external electric field (AEEF) within the range from -1 to 1 V Å on the CO adsorption behavior on various high and low-index facets of MgO. When CO is strongly adsorbed on MgO surfaces to form carbonate species, the coupling of electric fields with the resulting intrinsic dipole moment induces a 'switch' from a strongly chemisorbed state to a weakly chemisorbed or physisorbed state at a critical value of AEEF.

Surface Tailoring-Modulated Bifunctional Oxygen Electrocatalysis with CoP for Rechargeable Zn-Air Battery and Water Splitting.

The transition metal phosphide (TMP)-based functional electrocatalysts are very promising for the development of electrochemical energy conversion and storage devices including rechargeable metal-air batteries and water electrolyzer. Tuning the electrocatalytic activity of TMPs is one of the vital steps to achieve the desired performance of these energy devices. Herein, we demonstrate the modulation of the bifunctional oxygen electrocatalytic activity of nitrogen-doped carbon-encapsulated CoP (CoP@NC) nanostructures by surface tailoring with ultralow amount (0.

Metavalent or Hypervalent Bonding: Is There a Chance for Reconciliation?

A family of solids including crystalline phase change materials such as GeTe and Sb Te , topological insulators like Bi Se and halide perovskites such as CsPbI possesses an unconventional property portfolio that seems incompatible with ionic, metallic, or covalent bonding. Instead, evidence is found for a bonding mechanism characterized by half-filled p-bands and a competition between electron localization and delocalization. Different bonding concepts have recently been suggested based on quantum chemical bonding descriptors which either define the bonds in these solids as electron-deficient (metavalent) or electron-rich (hypervalent).

Metavalent Bonding in 2D Chalcogenides: Structural Origin and Chemical Mechanisms.

An unusual set of anomalous functional properties of rocksalt crystals of Group IV chalcogenides were recently linked to a kind of bonding termed as metavalent bonding (MVB) which involves violation of the 8-N rule. Precise mechanisms of MVB and the relevance of lone pair of Group IV cations are still debated. With restrictions of low dimensionality on the possible atomic coordination, 2D materials provide a rich platform for exploration of MVB.

Ultrafast glimpses of the excitation energy-dependent exciton dynamics and charge carrier mobility in CsSnI nanocrystals.

Advancements in photovoltaic research suggest that tin-based perovskites are potential alternatives to traditional lead-based structures. CsSnI, specifically, stands out as a notable candidate, exhibiting impressive performance. However, its complete potential remains untapped primarily owing to the limited understanding of its photophysics.

Raman Evidence of Multiple Adsorption Sites and Structural Transformation in ZIF-4.

The zeolitic imidazolate framework, ZIF-4, exhibits soft porosity and is known to show pore volume changes with temperatures, pressures, and guest adsorption. However, the mechanism and adsorption behavior of ZIF-4 are not completely understood. In this work, we report an open to narrow pore transition in ZIF-4 around ∼ 253 K upon lowering the temperature under vacuum (10 Torr) conditions, facilitated by C-H···π interactions.

Metavalent Bonding Origins of Unusual Properties of Group IV Chalcogenides.

A distinct type of metavalent bonding (MVB) is recently proposed to explain an unusual combination of anomalous functional properties of group IV chalcogenide crystals, whose electronic mechanisms and origin remain controversial. Through theoretical analysis of evolution of bonding along continuous paths in structural and chemical composition space, emergence of MVB in rocksalt chalcogenides is demonstrated as a consequence of weakly broken symmetry of parent simple-cubic crystals of Group V metalloids. High electronic degeneracy at the nested Fermi surface of parent metal drives spontaneous breaking of its translational symmetry with structural and chemical fields, which open up a small energy gap and mediate strong coupling between conduction and valence bands making metavalent crystals highly polarizable, conductive, and sensitive to bond-lengths.

Tuberculosis diagnosis and management in the public versus private sector: a standardised patients study in Mumbai, India.

Background: There are few rigorous studies comparing quality of tuberculosis (TB) care in public versus private sectors.

Methods: We used standardised patients (SPs) to measure technical quality and patient experience in a sample of private and public facilities in Mumbai.

Results: SPs presented a 'classic, suspected TB' scenario and a 'recurrence or drug-resistance' scenario.

Electron-Phonon Coupling Mediated Self-Trapped-Exciton Emission and Internal Quantum Confinement in Highly Luminescent Zero-Dimensional (Guanidinium)MnX (X = Cl and Br).

We report a large Stokes shift and broad emission band in a Mn-based organic-inorganic hybrid halide, (Guanidinium)MnBr [GuMBr], consisting of trimeric units of distorted MnBr octahedra representing a zero-dimensional compound with a liquid like crystalline lattice. Analysis of the photoluminescence (PL) line width and Raman spectra reveals the effects of electron-phonon coupling, suggestive of the formation of Frenkel-like bound excitons. These bound excitons, regarded as the self-trapped excitons (STEs), account for the large Stokes shift and broad emission band.

Glassy thermal conductivity in CsBiICl single crystal.

As the periodic atomic arrangement of a crystal is made to a disorder or glassy-amorphous system by destroying the long-range order, lattice thermal conductivity, κ, decreases, and its fundamental characteristics changes. The realization of ultralow and unusual glass-like κ in a crystalline material is challenging but crucial to many applications like thermoelectrics and thermal barrier coatings. Herein, we demonstrate an ultralow (~0.

Unusual CO Adsorption in ZIF-7: Insight from Raman Spectroscopy and Computational Studies.

Here, we use Raman spectroscopy to investigate temperature-dependent changes in the atomic-scale structure of the zeolitic imidazolate framework ZIF-7 in a CO atmosphere and uncover the mechanism of maximal CO adsorption at 206 K. At 301 K, the Raman spectra of ZIF-7 at various CO gas pressures reveal a narrow-pore (np) to large-pore (lp) phase transition commencing at 0.1 bar as a result of adsorption of CO, as evident in the appearance of Fermi resonance bands of CO at 1272 and 1376 cm.

CO Utilization Through its Reduction to Methanol: Design of Catalysts Using Quantum Mechanics and Machine Learning.

Reducing levels of CO, a greenhouse gas, in the earth's atmosphere is crucial to addressing the problem of climate change. An effective strategy to achieve this without compromising the scale of industrial activity involves use of renewable energy and waste heat in conversion of CO to useful products. In this perspective, we present quantum mechanical and machine learning approaches to tackle various aspects of thermocatalytic reduction of CO to methanol, using H as a reducing agent.

Opportunities and challenges for 2D heterostructures in battery applications: a computational perspective.

With an increasing demand for large-scale energy storage systems, there is a need for novel electrode materials to store energy in batteries efficiently. 2D materials are promising as electrode materials for battery applications. Despite their excellent properties, none of the available single-phase 2D materials offers a combination of properties required for maximizing energy density, power density, and cycle life.

Local Symmetry Breaking Suppresses Thermal Conductivity in Crystalline Solids.

Understanding the correlations of both the local and global structures with lattice dynamics is critical for achieving low lattice thermal conductivity (κ ) in crystalline materials. Herein, we demonstrate local cationic off-centring within the global rock-salt structure of AgSbSe by using synchrotron X-ray pair distribution function analysis and unravel the origin of its ultralow κ ≈0.4 W mK at 300 K.

Activation of CO and CH on MgO surfaces: mechanistic insights from first-principles theory.

One of the most challenging topics in heterogeneous catalysis is conversion of CH to higher hydrocarbons. Direct conversion of CH to ethylene can be achieved the oxidative coupling of methane (OCM) reaction. Despite studies which have shown MgO to activate CH and initiate the OCM reaction, its large-scale applications face a significant impediment due to formation of a byproduct, CO, and poisoning of the catalyst due to carbonate formation.

Modulation of the electronic structure and thermoelectric properties of orthorhombic and cubic SnSe by AgBiSe alloying.

Recently, single-crystals of tin selenide (SnSe) have drawn immense attention in the field of thermoelectrics due to their anisotropic layered crystal structure and ultra-low lattice thermal conductivity. Layered SnSe has an orthorhombic crystal structure () at ambient conditions. However, the cubic rock-salt phase (3̄) of SnSe can only be stabilized at very high pressure and thus, the experimental realization of the cubic phase remains elusive.