Second-order Constants Research Articles

Ultrafast degradation of Cu(II)-EDTA by peroxymonosulfate activated with polyoxometalate clusters intercalated layered double hydroxides: Simultaneous decomplexation and resourcelization

Technologies used to handle metal pollution are often ineffective for complexed metals, which have refractory biodegradability, high solubility, and strong mobility, posing significant threats to the ecological environment. This work proposed a novel catalytic system for the proper disposal of Cu(II)-EDTA pollution. Polyoxometalate cluster intercalated CaFe layered double hydroxide (LDH-CoPW) prepared through a mild and convenience method was applied to activate peroxymonosulfate (PMS) for the degradation of Cu(II)-EDTA and the simultaneous immobilization of the released Cu(II). Compared to direct waste or complex regeneration of catalysts, the application of used LDH-CoPW in clean energy production was proposed to further reduce carbon emissions. Under the combination of 0.1 g/L of LDH CoPW and 0.1 mM of PMS, nearly 100 % of Cu(II)-EDTA was removed within 3 min of reaction time, and 49.6 % of Cu(II) was adsorbed within 60 min of reaction time. The second-order reaction kinetic constants of Co(IV) = O with various probes were confirmed by competition kinetics method. Based on this, Co(IV) = O was identified as the dominant RSs using a scientific probe-based kinetic model. Furthermore, CaFe-LDH did not directly activate PMS but ensured the reactivity of the catalytic system by promoting the redox cycle of cobalt species. Finally, due to the regulation of Cu on the electronic structure of the catalyst, the electrochemical performance of the used LDH-CoPW surpassed that of fresh LDH-CoPW and CaFe-LDH, showing great potential in clean energy production.

Simultaneous Emerging Contaminant Removal and H2O2 Generation Through Electron Transfer Carrier Effect of Bi─O─Ce Bond Bridge Without External Energy Consumption.

Conventional advanced oxidation processes (AOPs) require significant external energy consumption to eliminate emerging contaminants (ECs) with stable structures. Herein, a catalyst consisting of nanocube BiCeO particles (BCO-NCs) prepared by an impregnation-hydrothermal process is reported for the first time, which is used for removing ECs without light/electricity or any other external energy input in water and simultaneous in situ generation of H2O2. A series of characterizations and experiments reveal that dual reaction centers (DRC) which are similar to the valence band/conducting band structure are formed on the surface of BCO-NCs. Under natural conditions without any external energy consumption, the BCO-NCs self-purification system can remove more than 80% of ECs within 30min, and complete removal of ECs within 30min in the presence of abundant electron acceptors, the corresponding second-order kinetic constant is increased to 3.62 times. It is found that O2 can capture electrons from ECs through the Bi─O─Ce bond bridge during the reaction process, leading to the in situ production of H2O2. This work will be a key advance in reducing energy consumption for deep wastewater treatment and generating important chemical raw materials.

High throughput screening of semiconductors with low lattice thermal transport induced by long-range interactions.

Semiconductors with long-range interactions (LRI) due to resonant bonding exhibit delocalized electronic states and low lattice thermal conductivity, contributing to the efficiency of heat-to-electricity conversion. Here, we build a descriptor for high-throughput screening of LRI materials from the second-order interaction force constants. We identify 75 semiconducting candidates from the binary compounds in the MatHub-3d database that contain LRI. By analyzing the bonding properties of LRI atoms, we classify LRI in materials into two categories: type I and type II. In the structural unit of type I LRI, the atoms have strong bond connections, while a weak bond exists between the two groups in the structural unit of type II LRI. We have identified atypical type I LRI formed by Sb-Sb and Mg-Mg pairs in the emerging thermoelectric material Mg3Sb2, resulting in the softening of TA1 phonons and large anharmonicity. For type II LRI, the LRI of Ge-Ge and Se-Se pairs in R3m-GeSe can cross different layers. Moreover, we observe a combination of type II LRI and rattling effect in BaSe2 to restrict thermal transport. This work is of great significance for understanding the relationship between LRI and thermal transport properties, and for designing new LRI-induced low lattice thermal conductivity materials.

Kinetic constants and transformation products of ornidazole during ozonation

Ornidazole (ONZ), a nitroimidazole antibiotic detected in water bodies, may negatively impact the aquatic ecosystem. Its reaction kinetics during ozonation which is a feasible and applicable technology to control the contamination of emerging contaminants, however, has not been reported in literature. In this study, we measured the apparent second-order kinetic constant of ONZ with ozone molecules via the excessive ozone method and the competing method which led to an average value of 103.8 ± 2.7 M−1 s−1 at pH 7. The apparent second-order kinetic constant of ONZ with HO• was calculated to be 4.65 × 109 M−1 s−1 with the concept of Rct measured via para-chlorobenzoic acid as a probe. The transformation products (TPs) of ONZ during ozonation at pH 3 and pH 11 were separately analyzed with HPLC-MS/MS and some unique products were found at pH 11, reflecting the influence of HO•. The toxicity of individual TPs was predicted with the tool of T.E.S.T. It was found that 62% of 21 identified TPs could be more toxic than ONZ in terms of at least one acute toxicity endpoint, including chlorinated amines and N-oxides. The analysis with a respirometer further revealed that the toxicity of mixing TPs generated at HO• rich conditions was slightly lower than O3 dominated conditions. In general, this study provides the basic kinetic data for designing ozonation processes to eliminate ONZ and the important reference for understanding the toxicity evolution of ONZ during ozonation.

The influence of a permanent magnetic field on the crystallization of calcium carbonate from carbonate aqueous solutions

The effect of a permanent magnetic field on the crystallization of calcium carbonate from carbonate aqueous solutions was studied. Based on the equations for the first- and second-order dissociation constants of carbonic acid, the stability constants of NaCO3- and NaHCO30 complexes, the mass balance and electroneutrality equations, the values of the system components and the ratio between the components of the carbonate subsystem were determined, and it was established that the main species in experimental conditions are СО32-, NaСО3- and HСО3- and the main components of the carbonate subsystem are СО32- (86.7%) and HСО3- (13.19%). Studies have shown that with a significant excess of CO32- over HCO3- ions in the solution at temperatures of 18-20˚C, calcite and vaterite are most likely formed. During the crystallization of calcium carbonate from an aqueous carbonate solution in a magnetic field of 125-250 mT, the size of the crystallites increases significantly compared to the absence of a magnetic field.

Tracking Multiphase Flows through Steep Reservoirs with External Constraint

Problem statement: The study offers theoretical formulations for high-viscosity particulate flows in inclined reservoirs, taking into account the presence of homogeneous spheroidal particles of various types to produce discrete two-phase suspensions. Purpose: The primary objective of this analytical and comparative study is to identify the most dependable nanoparticles among hafnium and crystal metals that are suspended in an Eyring–Powell fluid through an inclined channel while being subjected to external magnetic and gravitational forces. Solution methodology: The flow dynamics of multiphase flows are formulated utilizing the stress tensor of the base fluid. The regular perturbation method (RPM) is employed to attain a more closed-form solution. The perturbation method is frequently employed in engineering problems to obtain an approximated solution, even when demonstrating the convergence of the solution is challenging. The rough solution is also validated through a thorough parametric analysis that shows the role of relevant parameters that contribute to the multiphase flow. Results: A concise parametric study is carried out against some of the most pertinent parameters and reveals that additional particles have promising effects on the momentum of each multiphase flow, whereas Eyring–Powell multiphase suspensions lessen in momentum due to strong internal viscous forces. The velocity of fluid and particle phases diminish with Hartmann number M and Froude number Fr. The second-order material constant B and concentration of nanoparticles C boost the motion of the fluid. The velocities of the particulate phase are quicker than the fluid phase. The hafnium particle is more reliable than crystal particles. Solution benchmark: Numerical and graphical findings have also been compared with the existing literature for the limiting case and found to be fully in agreement. Applications: This study’s findings provide a wider understanding of subterranean flows, specifically within the petroleum sector, with a focus on multiphase flows. Originality: The current study represents the authors’ original work and has not been previously submitted or published elsewhere.

Controlling the reactivity of hydrophilic bark extractives as biopolyols in urethane-formation reactions using various catalysts

The composition, functionality, and reactivity of black alder (Alnus glutinosa) bark extractives as a biopolyol with polymeric diphenyl methane diisocyanate (PMDI) have been studied using a variety of methods, including HPLC, GPC, GC, wet chemistry, and isothermal calorimetry. The Black alder (BA) bark extractives were identified as a prospective polyol consisting mainly of the oregonin-xyloside form of diarylheptanoid, which contains OH groups that are almost equally represented by phenolic and aliphatic origins. To identify catalysts that effectively increase the reactivity of low-active phenolic OH groups in urethane formation reactions, the kinetics of extractives and model compounds' interaction with PMDI catalyzed with tin organic, dibutyl tin dilaurate (DBTDL) and tertiary amine, 1,4-diazabicyclo[2.2.2]octane (DABCO) catalyst in dimethylsulfoxide (DMSO) solution were studied. The results showed that DABCO resulted in a fourfold higher reactivity of phenolic groups with PMDI compared to DBTDL catalyzed reactions. Furthermore, the reactivity of phenolic groups with PMDI catalyzed by DABCO was almost twofold greater than that of aliphatic OH catalyzed by DBTDL. The second-order constants of 31.9 × 10−4 mol·L−1·s−1 and 53.7 × 10−4 mol·L−1·s−1 were determined for the interaction of extractives with PMDI in the presence of DBTDL and DABCO, respectively. The disappearance of the radical scavenging effect of phenolic compounds in extractives derived PU elastomers obtained with DABCO catalyst indicates complete reactions of phenolic groups with isocyanate, while these groups remain partly free in the case of DBTDL catalysis. It is assumed that a combination of DBTDL and DABCO catalysts will be necessary to achieve high crosslinking while leaving a small portion of free phenolic groups in the bio-based PU network, thus obtaining material with high mechanical properties and thermal oxidative stability.

Water Self-Purification with Zero External Consumption by Livestock Manure Resource Utilization.

Improper disposal of waste biomass and an increasing number of emerging contaminants (ECs) in water environment are universal threats to the global environment. Here, we creatively propose a sustainable strategy for the direct resource transformation of livestock manure (LM) into an innovative catalyst (Fe-CCM) for water self-purification with zero external consumption. ECs can be rapidly degraded in this self-purification system at ambient temperature and atmospheric pressure, without any external oxidants or energy input, accompanied by H2O and dissolved oxygen (DO) activation. The performance of the self-purification system is not affected by various types of salinity in the wastewater, and the corresponding second-order kinetic constant is improved 7 times. The enhanced water self-purification mechanism reveales that intermolecular forces between anions and pollutants reinforce electron exchange between pollutants and metal sites on the catalyst, further inducing the utilization of the intrinsic energy of contaminants, H2O, and DO through the interfacial reaction. This work provides new insights into the rapid removal of ECs in complicated water systems with zero external consumption and is expected to advance the resource utilization of livestock waste.

A novel ZnO/CQDs/PVDF piezoelectric system for efficiently degradation of antibiotics by using water flow energy in pipeline: Performance and mechanism

Using clean and natural energy from the environment to treatment of organic pollutants is a sustainable approach to alleviate energy and environmental problem. This work prepared a novel ZnO/CQDs/PVDF pipe system with excellent piezoelectric properties for efficient tetracycline (TC) degradation. The piezoelectric catalytic activity of ZnO/CQDs/PVDF was excited by hydrodynamic force to achieve a removal rate of 95.17 % of TC within 70 min with a second-order kinetic constant of 0.0185 L∙(mg min)−1, it can still maintain high stability after 35 h cycles. Most importantly, the water flow-driven piezoelectric catalytic system has extremely low energy consumption, is only 17.57 % of that of the ultrasonic system. The CQDs promote the transfer rate of ZnO surfaces charges, and PVDF with flexible β-rich phases were more sensitive to low-frequency pressure responses. ∙OH and ∙O2- radicals were demonstrated to the main radicals for the degradation of tetracycline. Based on LC-MS results and DFT calculations, the degradation mechanisms of tetracycline molecules, including hydroxylation, C-C, and C-N bond cleavage processes, were successfully predicted. In addition, ZnO/CQDs/PVDF pipe have obvious inhibitory effect on the biotoxicity of intermediates generated during the degradation process and exhibit excellent antibacterial ability. This work demonstrated that ZnO/CQDs/PVDF pipe have efficient utilization of low-frequency water flow energy and shows great potential in practical applications.

Kinetics and Mechanisms of Aqueous-Phase Reactions of Triplet-State Imidazole-2-carboxaldehyde and 3,4-Dimethoxybenzaldehyde with α,β-Unsaturated Carbonyl Compounds.

Reactions in the atmospheric aqueous phase are an important source of secondary organic aerosols (SOA). Within the present study, the reactions of triplet-state imidazole-2-carboxaldehyde (32-IC*) with methyl vinyl ketone (MVK, R1), methacrolein (MACR, R2), and methacrylic acid (MAA, R3), as well as the reaction of triplet-state 3,4-dimethoxybenzaldehyde (3DMB*) with the unsaturated compounds (MVK, R4), (MACR, R5), and (MAA, R6), in the aqueous phase were investigated using laser flash excitation-laser long path absorption and ultraperformance liquid chromatography coupled with high definition electrospray ionization spectrometry. The second-order reaction constants for 32-IC* were determined to be k1 = (1.0 ± 0.1) × 109 L mol-1 s-1 at pH 4-5 and 9, k2 = (1.4 ± 0.4) × 109 L mol-1 s-1 and (1.5 ± 0.1) × 109 L mol-1 s-1 at pH 4-5 and 9, and k3 = (1.4 ± 0.4) × 109 L mol-1 s-1 and (1.1 ± 0.4) × 108 L mol-1 s-1 at pH 4-5 and 9, respectively. The main products of the [2 + 2] photocycloaddition reactions of 32-IC* with both monomer and dimer of MVK as well as MACR were characterized. Similarly, the [2 + 2] photocycloaddition of the carbonyl of the excited triplet state of 3,4-dimethoxybenzaldehyde (3DMB*) with MVK was observed. The second order rate constants for the reactions of 3DMB* were determined: k4 = (1.5 ± 0.2) × 108 L mol-1 s-1, k5 = (2.8 ± 0.5) × 108 L mol-1 s-1, and k6 = (5.2 ± 1.2) × 106 L mol-1 s-1 at pH 9. The studied reactions show that different triplet photosensitizers react with strongly varying rate constants. Advanced CAPRAM process model studies show that active photosensitizers such as 3DMB* can quickly react with unsaturated organic compounds under deliquesced aerosol conditions modifying SOA, while the quenching with oxygen dominates the excited photosensitizer loss under cloud conditions.

Environmental Persistence of the Antidepressant Fluoxetine and Its Pharmaceutical Alternative: Kinetics of Oxidation and Mathematical Simulations

To investigate the impact of antidepressants (ANT) in water, estimates of the direct and indirect photolysis of standard fluoxetine hydrochloride (FLX) and a pharmaceutical alternative, fluoxetine sulfate (FLXSO4), were evaluated. The second-order kinetic constants of the ANT and reactive photoinduced species (RPS) (singlet oxygen, 1O2; hydroxyl radicals, HO•; and triplet excited states of chromophoric dissolved organic matter, 3CDOM*) were obtained by competition kinetics under simulated solar radiation. These parameters were used in combination with water characteristics to assess the environmental persistence of the ANT based on mathematical kinetic simulations. The results indicated that the reactions with HO• (kFLX,HO• = (2.54 ± 0.06) × 109 L mol−1 s−1; kFLXSO4,HO• = (3.07 ± 0.03) × 109 L mol−1 s−1) and 3CDOM* (kFLX,3CDOM* = (2.67 ± 0.05) × 109 L mol−1 s−1; kFLXSO4,3CDOM* = (1.48 ± 0.03) × 109 L mol−1 s−1) play a more important role in the degradation of ANT compared to the reactions with 1O2 (kFLX,1O2 = (1.37 ± 0.07) × 107 L mol−1 s−1; kFLXSO4,1O2 = (1.63 ± 0.33) × 107 L mol−1 s−1). The main removal pathways were biodegradation and direct photolysis with persistence in the following order FLX > FLXSO4. Therefore, the presence of sulfate anions can contribute to the degradation of fluoxetine in sunlit environmental waters.

Anharmonicity-induced strong temperature-dependent thermal conductivity in CuInX2 ( X=Se , Te)

The lattice thermal $\mathrm{conductivity}({\ensuremath{\kappa}}_{\mathrm{L}}$) of most single crystals usually follows ${T}^{\ensuremath{-}1}$ temperature dependent relation at high temperature region. Here, we investigate the microscopic mechanism of the significant deviation of ${\ensuremath{\kappa}}_{\mathrm{L}}\ensuremath{\sim}{T}^{\ensuremath{-}1}$ rule in Cu-based chalcopyrite compounds $\mathrm{CuIn}{X}_{2}$($X$=Se, Te) by performing first-principles calculations and solving Peierls-Boltzmann transport equation with phonon anharmonic renormalization. The temperature sensitive second-order force constants lead to the dramatically softened optical phonon bands, which contributes to the enlarged phonon scattering phase space and consequent enhanced scattering rate. The strong temperature dependent thermal conductivity in $\mathrm{CuIn}{X}_{2}$($X$=Se, Te) can be well reproduced when calculating thermal conductivity with renormalization force constants. The motion of Cu contributes the most to the large anharmonicity at high temperature, which makes the anharmonic renormalization non-negligible for estimating accurate lattice dynamic and thermal conductivity. Our work will deepen the understanding of thermal transport property of Cu-based chalcopyrite, which is helpful for designing better thermoelectric or photovoltaic devices.

First-principles prediction of the lattice thermal conductivity of two-dimensional (2D) h-BX (X = P, As, Sb) considering the effects of fourth-order and all-order scattering

Recently, cubic boron arsenide (c-BAs) has attracted global attention due to its higher lattice thermal conductivity (κL), which is comparable to diamond, and excellent thermal properties. Can c-BAs achieve the leap in κL after transforming its structure from three-dimensional (3D) to two-dimensional (2D) like diamond to graphene? Previous studies have only investigated the κL considering three-phonon scattering and isotope scattering, and the calculated results are diverse. In this study, we first calculate second-order interatomic force constants (IFCs) and third-order IFCs to iteratively solve the Boltzmann transport equation (BTE) and to obtain the κL3 of monolayer hexagonal BX (X = P, As, Sb), h-BX (X = P, As, Sb), considering only three-phonon and isotope scattering. The corresponding κL3 of h-BX are 278.2, 205.7, and 20.2 W/mK at room temperature, and we explain the monotonous change that κL3 decreases with the increase of average atomic mass (mavg) different from previous studies. Subsequently we use regular residual analysis (RRA) to determine the necessity of including four-phonon scattering when calculating the κL of monolayer h-BX. By calculating the fourth-order IFCs, we obtain the κL3+4 of monolayer h-BX including four-phonon scattering. The values of κL3+4 at room temperature are 61.12, 37.99, and 5.73 W/mK, which are highly consistent with the κL∞ of monolayer h-BX as predicted by the phonon spectral energy density (SED) method. The phonon SED method considers all-order scattering and gives values of 54.05 ± 21.48 W/mK (h-BP), 18.20 ± 4.47 W/mK (h-BAs), and 2.46 ± 0.34 W/mK (h-BSb), respectively. Our results show that the influence of four-phonon scattering on the κL of monolayer h-BX is significant, and the κL3+4 and κL∞ still undergo monotonic changes after including four-phonon scattering. The main factors that determine the low (ultra-low) κL of monolayer h-BAs (h-BSb) are large mavg and weaker bonding strength, the existence of intermediate frequency ZO and scattered acoustic branches, the strong anharmonicity caused by the in-plane vibrations of As (Sb) atoms, and four-phonon scattering. This study aims to end the variance within monolayer h-BAs κL numerical simulation and demonstrate the potential of monolayer h-BSb in thermoelectric field applications.

Degradation of Chloroquine Phosphate by UV-activated Persulfate

The degradation of chloroquine phosphate (CQP), an anti-COVID-19 drug, was investigated in a UV-activated persulfate system (UV/PS). The second-order rate constants of CQP with hydroxyl radicals (HO·) and sulfate radicals (SO4-·) were determined using a competition kinetics experiment, and the effects of persulfate concentration, pH, and inorganic anions on the degradation of CQP were also systematically studied. Furthermore, a kinetic model was established to predict the concentration of CQP and major free radicals to explore its mechanism of influence. The results showed that the degradation efficiency of CQP could reach 91.3% after 10 min under UV/PS, which was significantly higher than that under UV, sunlight, or PS alone. At pH=6.9, the second-order rate reaction constants of CQP with HO· and SO4-· were 8.9×109 L·(mol·s)-1and 1.4×1010 L·(mol·s)-1, respectively, and the main active species was SO4-·. The degradation rate of CQP increased with increasing concentrations of PS and decreased with the addition of HCO3- and Cl-. The removal efficiency of CQP was inhibited under stronger alkaline conditions. N-de-ethylation, cleavage of the C-N bond, and hydrogen abstraction were proposed as the principal pathways of CQP degradation based on LC-MS analysis. The mineralization rate of CQP could be improved by increasing PS concentration and pH values. This study could be helpful for the treatment of anti-COVID-19 pharmaceutical wastewater.

Bioinspired enzymatic compartments constructed by spatiotemporally confined in situ self-assembly of catalytic peptide

Enzymatic compartments, inspired by cell compartmentalization, which bring enzymes and substrates together in confined environments, are of particular interest in ensuring the enhanced catalytic efficiency and increased lifetime of encapsulated enzymes. Herein, we constructed bioinspired enzymatic compartments (TPE-Q18H@GPs) with semi-permeability by spatiotemporally controllable self-assembly of catalytic peptide TPE-Q18H in hollow porous glucan particles (GPs), allowing substrates and products to pass in/out freely, while enzymatic aggregations were retained. Due to the enrichment of substrates and synergistic effect of catalytic nanofibers formed in the confined environment, the enzymatic compartments exhibited stronger substrate binding affinity and over two-fold enhancement of second-order kinetic constant (kcat/Km) compared to TPE-Q18H nanofibers in disperse system. Moreover, GPs enabled the compartments sufficient stability against perturbation conditions, such as high temperature and degradation. This work opens an intriguing avenue to construct enzymatic compartments using porous biomass materials and has fundamental implications for constructing artificial organelles and even artificial cells.

Improved Extraction of Second-Order Material Constants for Current Generation Y-Grown La₃Ga5.5Nb0.5O₁₄ (LGN) Crystal.

With higher demand for sensor development, piezoelectric materials with advanced performance and wide availability draw more attention today. Accurate second-order material constants are necessary for modeling and mechanical design of sensors that make use of langanite (La3Ga5.5Nb0.5O14, LGN) crystals. We report here on room temperature LGN bulk acoustic wave (BAW) velocities obtained with reduced uncertainties using ultrasound measurements and taking advantage of the cross correlation signal processing technique, and a full set of LGN material constants extracted from the BAW velocity results. Our results compare favorably with prior results assessed as using a reliable measurement technique, and differ in expected fashion from other results based on techniques that do not address a known weakness in the measurement technique.

Purification and Characterization of Extracellular Cr(VI) Reductase from Bacillus amyloliquefaciens (CSB 9) isolated from Chromite Mine Soil for Detoxification of Hexavalent Chromium

Chromate is widely used industrial pollutant which can be detoxified effectively using chromate reductase from chromium resistant bacteria. A soluble Cr(VI) reductase from Bacillus amyloliquefaciens (CSB 9) was extracted and purified to electrophoretic homogeneity through (NH4)2SO4 precipitation followed by dialysis and gel filtration chromatography with specific activity of 0.167 U/mg and 6% yield with 30.36-fold increase in purity. Based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the molecular weight of the purified enzyme was estimated to be ~ 116 KDa. Further, functional characterization with respect to pH, temperature and storage stability showed optimum Cr(VI) activity at 35 °C and pH 7.0 on standard analysis conditions. Using potassium dichromate as substrate, the enzyme kinetics showed maximum activity (Vmax) of 3.5 U/mL with its corresponding KM value of 27.78 μM and the second-order constant (Vmax/Km) 0.125 U/μM mL. The purified enzyme exhibited higher stability (μM/mg/min) when treated with additives such as metal ions K+ (1.3 ± 0.056), surfactant tween 80 (2.33 ± 0.52), inhibitor β-mercaptoethanol (0.67 ± 0.15) and organic solvent glycerol (1.33 ± 0.011). These remarkable qualities found with the chromate reductase produced by B. amyloliquefaciens (CSB 9) could make it an ideal candidate for bioremediation of hexavalent chromium under a wide range of environmental conditions.

Second-order magnetoelastic effects: From the Dirac equation to the magnetic properties of ultrathin epitaxial films for magnetic thin-film applications

Abstract It has always been the endeavour of Professor Kronmüller to combine various methods in order to attain a comprehensive understanding of a physical phenomenon on all relevant scales. In this spirit, we combine the phenomenological nonlinear theory of magnetoelasticity with the relativistic density functional electron theory to describe the magnetoelastic behaviour of epitaxial films. We explain the two already performed cantilever bending beam experiments on the magnetoelasticity and underpin the assumption that second-order magnetoelastic effects are very important for epitaxial Fe films. A complete set of six cantilever experiments is introduced which allows to calculate the intrinsic first- and second-order magnetoelastic constants for cubic materials, and these constants are calculated ab initio for Fe, face-centred cubic Co, Ni, Ni3Fe and CsCl-type CoFe.

Finite-temperature force constants are essential for accurately predicting the thermal conductivity of rutile TiO2

Phonon transport in rutile $\mathrm{Ti}{\mathrm{O}}_{2}$ between temperatures of 100 and 900 K is investigated using lattice dynamics calculations and the Boltzmann transport equation. Zero- and finite-temperature force constants are extracted from density functional theory calculations to examine the effects of finite temperature on phonon properties and thermal conductivity. Using the zero-temperature force constants leads to thermal conductivity predictions along the $a$ and $c$ axes that are 50% lower than experimental measurements at a temperature of 300 K. The underprediction increases as the temperature is further increased. Using temperature-specific force constants, however, leads to thermal conductivity predictions that fall within the uncertainty bounds of multiple sets of experimental measurements. Phonon mode analysis reveals that the thermal conductivity underprediction from the zero-temperature force constants is a result of an underprediction of phonon lifetimes. The lifetime underprediction results from the temperature dependence of (i) the second-order force constants, which set the phonon frequencies and thus the three-phonon scattering phase space, and (ii) the third-order force constants, which influence the intrinsic scattering rates. Our results emphasize the importance of including finite-temperature effects when studying phonon transport in oxides and inform how nanostructuring impacts the thermal conductivity of rutile $\mathrm{Ti}{\mathrm{O}}_{2}$.

The Thermal Stability of Janus Monolayers SnXY (X, Y = O, S, Se): Ab-Initio Molecular Dynamics and Beyond.

In recent years, the Janus monolayers have attracted tremendous attention due to their unique asymmetric structures and intriguing physical properties. However, the thermal stability of such two-dimensional systems is less known. Using the Janus monolayers SnXY (X, Y = O, S, Se) as a prototypical class of examples, we investigate their structure evolutions by performing ab-initio molecular dynamics (AIMD) simulations at a series of temperatures. It is found that the system with higher thermal stability exhibits a smaller difference in the bond length of Sn–X and Sn–Y, which is consistent with the orders obtained by comparing their electron localization functions (ELFs) and atomic displacement parameters (ADPs). In principle, the different thermal stability of these Janus structures is governed by their distinct anharmonicity. On top of these results, we propose a simple rule to quickly predict the maximum temperature up to which the Janus monolayer can stably exist, where the only input is the ADP calculated by the second-order interatomic force constants rather than time-consuming AIMD simulations at various temperatures. Furthermore, our rule can be generalized to predict the thermal stability of other Janus monolayers and similar structures.