Temperature-dependent Behavior Research Articles

Polarity-Reversal of Exchange Bias in van der Waals FePS3/Fe3GaTe2 Heterostructures.

Exchange bias (EB) in antiferromagnetic (AFM)/ferromagnetic heterostructures is crucial for the advancement of spintronic devices and has attracted significant attention. The common EB effect in van der Waals heterostructures features a low blocking temperature (Tb) and a single polarity. In this work, a significant EB effect with a Tb up to 150K is observed in FePS3/Fe3GaTe2 heterostructures, and in particular, the EB exhibits an unusual temperature-dependent polarity-reversal behavior. Under a high positive field-cooling condition (e.g., μ0H ≥0.5T), a negative EB field (HEB) is observed at low temperatures, and with increasing temperature, the HEB crosses zero at ≈20K, subsequently becomes positive and later approaches zero again at Tb. A model composed of a top FePS3/interfacial FePS3/Fe3GaTe2 sandwich structure is proposed. The charge transfer from Fe3GaTe2 to FePS3 at the interface induces net magnetic moments (∆M) in FePS3. The interface favors AFM coupling, and thus the reversal of ∆M of the interfacial FePS3 leads to the polarity-reversal of EB. Moreover, the EB can be extended to the bare Fe3GaTe2 region of the Fe3GaTe2 flake partially covered by FePS3. This work provides opportunities for a deeper understanding of the EB effect and opens a new route toward constructing novel spintronic devices.

Computer Simulation of Triazole-Modified Urethane Segments

The focus is on the development of siloxane-urethane block copolymer matrices for additive manufacturing applications, including soft robotics. Molecular dynamics simulations compare classical urethane segments with the triazole-modified ones, revealing temperature-dependent behaviors in their conformational structures. The results suggest the potential for tailoring the mechanical properties of polyurethanes through molecular modification, which is crucial for optimizing additive manufacturing processes. Further research could advance material design for customizable objects with desired mechanical response.

First Principle Study of Electronic, Optoelectronic, and Thermoelectric Properties of Zintl Phase Alloys BaAg2X2 (X = S, Se, Te) for Renewable Energy

Novel Zintl phases exhibiting promising thermoelectric properties have garnered considerable traction, largely attributed to the accuracy of computational estimates. In the present investigation, the density functional theory-based WIEN2k code is employed to analyze the structural, optoelectronic, and transport behavior of the BaAg2X2 (X = S, Se, Te) Zintl phase. All these compositions belong to the stable trigonal phase with nominal expansion in the unit cell with the replacement of S with Se and Te. A negative value of enthalpy of formation of -2.30, -2.0, and -1.80 for BaAg2S2, BaAg2Se2, and BaAg2Te2, respectively, assures their thermodynamic stability. These compositions demonstrate dynamic stability, as evidenced by the nonexistence of negative (-ve) frequency values in their phonon spectra. Increasing the size of chalcogens enhances the spin-orbit coupling and reduces the bandgap value from 2.10 - 1.55 eV. The examination of optical response suggests that studied compositions display high absorption and low energy loss in the visible range, rendering them suitable for optoelectronic devices. The temperature-dependent transport behavior is computed using BoltzTrap code, and the RT value of power factor is recorded as 0.89 × 1011, 0.65 × 1011, and 0.54 × 1011 Wm− 1K− 2 for BaAg2X2 (X = S, Se, Te). A high power factor value at elevated temperatures indicates the promising efficacy of studied compositions in thermoelectric device applications.

Experimental and Computational Study of Ethanolamine Ices under Astrochemical Conditions

Ethanolamine (NH2CH2CH2OH) has recently been identified in the molecular cloud G+0.693-0.027, situated in the SgrB2 complex in the Galactic center. However, its presence in other regions, and in particular in star-forming sites, is still elusive. Given its likely role as a precursor to simple amino acids, understanding its presence in the star-forming region is required. Here, we present the experimentally obtained temperature-dependent spectral features and morphological behavior of pure ethanolamine ices under astrochemical conditions in the 2–12 μm (MIR) and 120–230 nm (VUV) regions for the first time. These features would help in understanding its photochemical behavior. In addition, we present the first chemical models specifically dedicated to ethanolamine. These models include all the discussed chemical routes from the literature, along with the estimated binding energies and activation energies from quantum chemical calculations reported in this work. We have found that surface reactions CH2OH + NH2CH2 → NH2CH2CH2OH and NH2 + C2H4OH → NH2CH2CH2OH in warmer regions (60–90 K) could play a significant role in the formation of ethanolamine. Our modeled abundance of ethanolamine complements the upper limit of ethanolamine column density estimated in earlier observations in hot core/corino regions. Furthermore, we provide a theoretical estimation of the rotational and distortional constants for various species (such as HNCCO, NH2CHCO, and NH2CH2CO) related to ethanolamine that have not been studied in existing literature. This study could be valuable for identifying these species in the future.

Fluorescence temperature dependent behaviors of Eu3+/Mn4+ co-doping cubic and hexagonal ZnO-TiO2 compounds: Application in high sensitive optical thermometers

ZnTiO3:Eu3+,Mn4+ phosphors with hexagonal and cubic structure were synthesized by solvothermal method. The structure of ZnTiO3 depends on precursors and the annealing temperature. Inverse spinel Zn2TiO4 phase revealed the highest thermostability compared with cubic ZnTiO3 and hexagonal ZnTiO3 phases. The different phases of ZnTiO3 crystals exhibited different photoluminescence properties. The forbidden transition of 4A2g→2T2g for Mn4+ was observed in Zn2TiO4 and hexagonal ZnTiO3 (h-ZnTiO3) due to the decreased symmetry. The zero photon line (ZPL) assigned to 2Eg→4A2g transition of Mn4+ was absent in all type ZnTiO3 phases. A sharp emission peak at 714nm assigned to ν6 (Stokes emission) mode of Mn4+ in h-ZnTiO3, was present when the temperature was below 270K, and increased sharply in intensity with the temperature decreasing. The similar PL spectra of cubic ZnTiO3 and Zn2TiO4 co-doped with Eu3+ and Mn4+ show a wide emission band composed of Stokes and anti-Stokes modes. The calculated nephelauxetic parameter increases from 0.84 to 1.03 and 1.18 for Mn4+ in h-ZnTiO3, cubic ZnTiO3 and Zn2TiO4, respectively, indicating the covalency decreasing, which causes the red shift of ZPL in h-ZnTiO3. The Mn4+ emissions show stronger temperature dependence than that of Eu3+, especially for that in h-ZnTiO3 matrix. Based on the fluorescence intensity ratio between IEu3+ and IMn4+, the highest relative temperature sensitivity of 2.46%K-1 is observed in cubic ZnTiO3 (c-ZnTiO3) and Zn2TiO4. Under the excitation at 550nm, the highest relative sensitivity of 2.9%K-1 is achieved in c- and h-ZnTiO3 mixed phases.

Pitting corrosion resistance of tempered N08825 alloy in the inner layer of bimetallic composite pipe

Pitting corrosion resistance of N08825 alloy in the inner layer of bimetallic composite pipe SA210A/N08825 tempered at 570∼720 ℃ was investigated in NH4Cl solution by scanning electron microscopy (SEM), X-ray diffraction (XRD), and electrochemical measurement techniques. The M23C6 precipitates, observed at the grain boundaries of inner layer alloy 825, exhibit a temperature-dependent behavior during tempering at 570∼720 ℃. The quantity of M23C6 precipitates and the pitting corrosion resistance change with the tempering temperature. When the tempering temperature increases from 570 to 660 ℃, the quantity of M23C6 precipitates increases, with the pitting potential (Ep) decreasing from about 499 ± 8.6 to 354 ± 6.7 mVSCE, the passive current density (ip) increases from about 1.9 ± 0.2 to 2.45 ± 0.3 μA cm-2, and the average number of pits on the specimen surface rises from 3 to 7. Conversely, when the tempering temperature increases from 660 to 720 ℃, the quantity of M23C6 precipitates decreases, leading to the Ep increases from about 354 ± 6.7 to 394 ± 14.6 mVSCE, the ip decreases from about 2.45 ± 0.3 to 2.34 ± 0.4 μA cm-2, and the average number of pits on the specimen surface decreases from 7 to 6. There is a strong relationship between the M23C6 precipitates and the pitting corrosion resistance. As the quantity of M23C6 precipitates increases, it results in the expansion of Cr-depleted zones on the specimen surface, the rise of passive film defects, and a subsequent reduction in the pitting corrosion resistance of inner layer alloy 825.

Influence of composition and temperature on oxide film formation for Fe-Cr-Ni alloys in simulated PWR primary water

ABSTRACT The growth of oxide films on Fe-Cr-Ni alloys in simulated pressurized water reactor (PWR) primary system environments was investigated, with focus on the influence of alloy composition and temperature. Oxide film thicknesses were measured for 90 specimens prepared from compact tension (CT) test pieces. Cross-sectional observations were also conducted on coupon specimens using scanning transmission electron microscopy (STEM). The behavior of Ni-based alloys, specifically Alloy 600, and Fe-based alloys, specifically Type 316 stainless steel, were compared. Ni-based alloys exhibit superior corrosion resistance due to slower Fe diffusion kinetics compared to Fe-based alloys, leading to the formation of a nickel-enriched protective layer at the metal-oxide interface. The oxidation rates of Ni-based alloys follow an Arrhenius-type temperature dependence. In contrast, Fe-based alloys show a more complex temperature-dependent behavior, with reduced oxidation rates at higher temperatures that are likely due to changes in oxide dissolution. Higher chromium concentrations in both alloy types improve the protectiveness of the oxide film towards corrosion by forming a more compact inner oxide layer. The study identifies three primary factors influencing oxide film growth: reactions at the metal-oxide interface, diffusion within the oxide layer, and processes at the oxide-solution interface. The relative significance of these processes varies depending on the alloy composition and temperature.

Computational analysis of wildland fire resistance for transmission line tower

Finite element (FE) analysis of the transmission towers under a fire event and the accompanying wind is presented. Several key aspects (including temperature-dependent non-linear material properties, geometric non-linearity, member eccentricity due to the single-leg bolted connection, and the temperature-dependent connection behaviour in both the axial and the rotational directions) are considered. A quasi-static analysis is also employed in the FE model using the explicit solver available in Abaqus. The member temperature variation during a realistic fire event is derived analytically based on the fire intensity and the resultant vertical gas temperature distribution so that the effect of the realistic wildland fire can be input as a member temperature profile. First, fire design guidance in terms of the most critical heating and wind pattern, as well as the effect of fire-affected heights are provided based on the case study results. Then, further fire analysis is carried out to investigate the most critical fire scenario and to evaluate the vulnerability of the tower during a realistic fire event. Lastly, an evaluation of a commonly used spray-on thermal insulation and its effectiveness in reducing the member temperature and preserving ultimate strength during a catastrophic wildland fire event are presented. The FE simulations revealed that a 45-degree wind associated with partial side heating leads to a more critical degradation of the overall strength, whereas the effect of fire height is less obvious. In terms of the fire scenario, a longer fire duration associated with a slower wind is more critical for the fire resistance/rating.

Frequency and temperature-dependent dielectric behaviour of fresh Aloe vera at 1 to 20 GHz microwave frequency using time domain reflectometry

Frequency and temperature-dependent dielectric behaviour of fresh Aloe vera at 1 to 20 GHz microwave frequency using time domain reflectometry

Green synthesis of boehmite-reinforced cashew gum/polypyrrole biopolymer blend for advanced biomaterials

Electrically conducting biopolymer blend nanocomposites based on different contents of boehmite (BHM) reinforced cashew gum (CG) /polypyrrole (PPy) blend is synthesized by an in situ polymerization technique using water as a green solvent. The resulting bio-blend nanocomposites underwent comprehensive analysis concerning their structural, morphology, thermal, and electrical properties, such as dielectric constant, dielectric loss, electric modulus, and AC conductivity. The Fourier transform infrared spectroscopy (FTIR) spectra revealed the presence of metal oxide stretching in the blended nanocomposite at 512 cm−1. Field emission scanning electron microscopy (FE-SEM) confirmed the attachment and uniform dispersion of BHM within the CG/PPy blend at 7 wt% loading, and beyond this loading, the nanoparticles get agglomerated in the biopolymer blend. The glass transition temperature and thermal stability of all the blended nanocomposites are higher than that of the pure CG/PPy blend and these thermal properties increase with the loading of nanoparticles. Conductivity experiments demonstrated that as the nanofiller content increases up to 7 wt%, there is a concurrent rise observed in AC conductivity, dielectric loss, and dielectric constant. There is a substantial difference of 1.21 Scm−1 between the maximum and minimum AC electrical conductivity, at 102 Hz. However, a decrease in electrical properties is observed at the highest loadings of BHM due to the agglomeration of nanoparticles in the polymer blend matrix. The lowest activation energy value (0.049 × 10−4 eV) is also exhibited by 7 wt% BHM nanocomposites. Furthermore, the electrical properties of both CG/PPy and CG/PPy/BHM nanocomposites exhibited a temperature-dependent behavior, progressively increasing until reaching maximum values. This study suggests that such bio-based polymer dielectrics could be promising materials for various applications, offering enhanced thermal and electrical properties through careful control of nanofiller content and dispersion.

Opto/Thermoresponsive Multimode Luminescence in Eu- and Er-Activated CaF2 Phosphor for High-Security Anticounterfeiting.

As the landscape of information storage and security continues to evolve, the deployment of sophisticated anticounterfeiting strategies with robust security features and multimodal luminescent capabilities becomes imperative. In this work, Eu3+ and Er3+ ions are codoped into CaF2 phosphors to achieve multimodel optical output. The self-reduction of Eu3+ within the CaF2 matrix gives rise to the coexistence of Eu3+ and Eu2+ ions, which manifests as a color transition from orange to blue as the excitation wavelength is varied from 300 to 335 nm. Moreover, the distinct temperature-dependent behaviors of Eu3+ and Eu2+ ions underscore the material's visible temperature-sensitive luminescence properties, characterized by remarkable thermal sensitivity (Sa = 0.0156 K-1, Sr = 0.83%K-1). Additionally, the strategic introduction of Er3+ ions adds an extra dimension, enabling the realization of color-tunable upconversion luminescence through the fine-tuning of Er3+ concentration. This synergistic integration culminates in the establishment of an efficient three-path authentication model within the CaF2 host matrix, facilitating a dynamic multicolor response to changes in the excitation wavelength and temperature. By harnessing these diverse luminescent modalities, the study delivers a versatile and potent anticounterfeiting solution, advancing the frontiers of information security.

Two-Dimensional Hydration and Triple-Interlayer Lattice Structures in Sulfate-Intercalated Graphene Oxide Nanosheets

Sulfate anions (SO42−) are pivotal in various scientific and industrial domains, including mineralogy, biology, and materials science. While extensive research has elucidated sulfate hydration in bulk solids, liquids, and gaseous clusters, a significant gap persists in understanding sulfate interactions within two-dimensional materials, particularly graphene oxide (GO) nanosheets. This study investigates the intricate hydration phenomena and novel triple-interlayer lattice configurations that emerge from sulfate intercalation in GO nanosheets. Utilizing a straightforward methodology for obtaining precise X-ray measurements of confined nanospaces, we analyzed the temperature-dependent behavior and structural characteristics of these systems. Our findings reveal how sulfate ions modulate interlayer spacing, the dynamics of GO layers, and phase transitions. This research offers an atomic-scale understanding of hybrid hydration behaviors within confined SO4-H2O nano-environments, advancing our knowledge of sulfate interactions in two-dimensional materials.

A 0D Ge(II)-Halide-Based Perovskite with Enhanced Semiconducting Behavior for Electronic Capacitors.

Perovskite materials have surged to the forefront of materials science, captivating researchers worldwide with their distinctive crystal lattice arrangement and remarkable optical, electric and dielectric attributes. The current study focuses on the development of a novel zero-dimensional (0D) Ge(II)-based hybrid perovskite, formulated as NH3(CH2)2NH3GeF6, and synthesized through a gradual evaporation process conducted at room temperature. The crystal structure is characterized by an arrangement of organic cations and isolated octahedral [GeF6]2- groups. This configuration is stabilized by relatively weak intermolecular bonds. A comprehensive analysis of the material's thermal properties using differential scanning calorimetry (DSC) revealed a distinct phase transition occurring at approximately 323 K, which was further confirmed through electrical measurements. The studied compound provided a broad absorption range across the visible spectrum and an optical band gap of 3.30 eV, indicating its potential for semiconducting applications in optoelectronic devices. Photoluminescence PL analysis displays a blueish broad-band emission with a high color rendering index CRI value of 91, when excited at 325 nm. This emission primarily originates from the self-trapped excitons (STEs) recombination in the inorganic [GeF6]2-. Herein, the temperature-dependent behavior of grain conductivity exhibited an Arrhenius-type pattern, with an activation energy (E a) of 0.46 eV, confirming the semiconductor nature of the investigated compound. In addition, a deep investigation of the alternating current conductivity, analyzed using Jonscher's law, demonstrates that the conduction mechanism is effectively described by the correlated barrier hopping (CBH) model. The dielectric performances show a significant dielectric constant (ε' ∼ 103). Thus, all these interesting physical properties of this hybrid perovskite have paved the way for advancements in various technological applications, particularly in the field of electronic capacitors.

Effect of succinonitrile on the structural, ion conductivity, and dielectric properties of PVDF‐HFP based solid polymer electrolytes

AbstractA detailed account of the poly(vinylidene difluoride‐co‐hexafluoropropylene) (PVDF‐HFP)/succinonitrile (SN)/lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) based solid polymer electrolytes (SPEs) of various compositions is reported. SN is incorporated as plasticizer, while LiTFSI is employed as the source of lithium ions. Fourier transfer infrared (FTIR) spectroscopy reveals the formation of polar and electroactive γ crystal phase by PVDF in pristine PVDF‐HFP and the prepared SPE films. FTIR further confirms the interaction between the host polymer and the salt and between the salt and the plasticizer. The interaction between the salt and plasticizer suggests that SN not only offers the plasticization effect but also facilitates salt dissociation. The ion conductivity increases with increasing salt content up to 20 wt% but beyond that concentration a decline in ion conductivity is observed, which could be attributed to the ion pair association or cluster formation due to the excess salt concentration that reduces the availability of free ions and ultimately leads to the reduction in ion conductivity. After including SN in the SPE formulation, electrochemical impedance spectroscopy reveals a substantial increase in room temperature ion conductivity of the SPE from ~1.08 × 10−5 S cm−1 for pristine SPE with 20 wt% salt to ~2.7 × 10−4 S cm−1 for plasticized SPE with 40 wt% SN and 20 wt% salt. This is attributed to the plasticizing effect of SN that enhances ion mobility through the matrix and to the increased charge carrier concentration (SN facilities salt dissociation). The fabricated SPEs exhibit a significant enhancement in ion conductivity with increasing temperature and the maximum ion conductivity of 1.1 × 10−3 S cm−1 is attained at 393 K by plasticized SPE with 40 wt% SN content. The ion conductivity of all the prepared SPEs follows the temperature dependent Arrhenius behavior, suggesting the thermally activated ion hopping mechanism of ionic conduction. Further, the plasticized SPEs display near unity ion transference number indicating the predominance of the ionic mode of conduction. The dielectric and electric modulus analysis reveal a faster relaxation phenomenon and hence higher ion conductivity of the prepared SPEs with increasing salt and plasticizer content.

STUDY THE ELECTRICAL PROPERTIES OF GRAPHENE OXIDE – NANOCELLULOSE COMPOSITE

This study investigates the electrical properties of a graphene oxide (GO) and nanocellulose (NC) composite using impedance spectroscopy, complemented by thorough characterization through Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and scanning electron microscopy (SEM). FTIR analysis revealed characteristic peaks corresponding to functional groups present in both GO and NC, providing insights into their chemical composition. XPS spectra exhibited distinctive peaks indicative of carbon and oxygen bonding states, elucidating the surface chemistry of the materials. Raman spectroscopy provided information on the structural order and defects within the samples, particularly highlighting the graphitic structure of GO. SEM images revealed the morphological features of the composite membrane, showcasing the distribution of NC particles and structural modifications induced by their incorporation. Impedance spectroscopy was utilized to investigate the electrical conductivity of the GO-NC composite. Results indicated a temperaturedependent behavior, with an increase in conductance observed as the temperature rose within the operational range of fuel cells. Remarkably, the addition of NC did not significantly alter the conductive behavior of the composite, suggesting compatibility and stability. In summary, this comprehensive characterization using multiple analytical techniques offers valuable insights into the electrical properties of the GO-NC composite. The findings suggest its potential for various applications requiring enhanced electrical conductivity, particularly in fuel cell technology.

Optimisation, dielectric properties, and antibacterial efficacy of copper-grafted MgO nanoparticles synthesized via sol-gel method

This is the first study to optimize magnesium oxide nanoparticles by grafting copper as an effective antibacterial against prevalent pathogenic microorganisms, which were synthesized by sol-gel method with a particle size of 11–17 nm. At a preparation temperature of 70 °C, copper was added at rates of 2.5 wt%, 5 wt%, 7.5 wt% and 10 wt%. The particles were heated at 600 °C. Nanoparticles were analyzed using XRD, FTIR, UV–Vis spectrum, Raman, TGA-DTA, SEM, EDX, zeta potential and TEM. XRD study revealed the crystal structure of the space group of MgO nanoparticles is cubic. Optical measurements yielded optical gap values falling within the range of 2.35 eV, which was reduced to 2.20 eV. The presence of the copper dopants in the MgO host lattice was confirmed by FTIR analysis. It reveals the existence of Mg-O-Cu, Mg-O, and Mg-O-Mg bonds. Additionally, the dielectric and electrical characterization of MgO was conducted using complex impedance spectroscopy over a frequency range of 10–106 Hz and conductivity measurements across a temperature range of 60–380 °C. The real and imaginary parts of the dielectric constant showed both frequency-dependent and temperature-dependent behaviors. Notably, the variations observed in the imaginary component of the modulus and impedance at the maximum frequency indicates a relaxation process that is not of the Debye type, with calculated activation energies (Ea). Moreover, the samples were evaluated against various bacteria, including, -ve gram (Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa), and +ve gram (Staphylococcus aureus, and Streptococcus pneumonia) using two different techniques. Studies have shown that copper-containing samples exhibit resistance to these bacteria. These findings suggest that the samples have potential as useful biomaterials in nanobiotechnology.

Structure analysis (XRD and Neutrons) and hydrogen storage properties of Hf1-xTixNbVZr BCC high entropy alloys

The hydrogen storage properties of Hf1-xTixNbVZr high entropy alloys (HEAs) synthesized by arc melting have been investigated. The first hydrogenation of the alloys was performed at room temperature under 20 bars of hydrogen pressure. Results show an increase in gravimetric hydrogen content with Ti substitutions. Upon hydrogenation, the multiphase alloys (x = 0 and x = 0.25) exhibit a combination of faces-centred-cubic (FCC) hydride and C15 Laves phases, while single-phase alloys (x = 0.5, 0.75, and 1) display FCC structures.The crystal structure evolution during dehydrogenation of HfNbVZr (x = 0) and TiNbVZr (x = 1) HEAs was examined using in-situ neutron diffraction. The analysis demonstrates temperature-dependent desorption behaviour, with HfNbVZr displaying lower desorption temperatures compared to TiNbVZr. Additionally, in-situ neutron diffraction experiments during deuterium desorption indicate a two-step phase transition from FCC dihydride to BCT monohydride, followed by a transition to BCC.

Temperature-dependent deformation behavior of Hastelloy X Ni-based superalloy fabricated via laser powder bed fusion

Understanding the deformation behavior of additive manufacturing components across a wide spectrum of operating temperatures is crucial from an application standpoint. This study investigated the tensile deformation behavior of Hastelloy X (HX), fabricated via laser powder bed fusion (LPBF), over a temperature range of -50 °C to 900 °C through uniaxial tensile tests. The focus was on the temperature-dependent tensile properties and deformation mechanisms of HX in a fully heat-treated condition, involving initial hot isostatic pressing followed by solution treatment. The results indicate that as the temperature increases, the ultimate tensile strength decreases sharply from approximately 790 MPa at -50 °C to 610 MPa at 200 °C, then gradually declines to 530 MPa at 600 °C, and finally drops to 230 MPa at 900 °C. Meanwhile, the yield strength falls rapidly from 345 MPa at -50 °C to 230 MPa at 200 °C, then slowly reduces to 170 MPa at 600 °C, stabilizing up to 900 °C. Electron back scattered diffraction analysis revealed that with rising temperature, the predominant plastic deformation mechanism transitions from deformation twinning to slip bands and eventually to dynamic recrystallization. Remarkably, the strain hardening capacity increases with rising temperature below 600 °C, attributed to the beneficial effects of deformation twins and subsequent slip bands. Furthermore, dynamic strain aging takes place between 300 °C and 600 °C, slightly limiting the improvement of plasticity within this intermediate temperature range. Understanding these temperature-dependent deformation mechanisms in heat-treated LPBF HX would provide valuable insights into its performance over a wide range of service temperatures.

An efficient bio-stabilization technology with bio‑carbonation of reactive magnesia for soil improvement in cold regions

Low curing temperature conditions (5–15 °C) in cold regions pose major challenges for soil improvement using conventional binders, underscoring the urgent need for solutions to enhance soil strength and ensure engineering safety. This study investigated the feasibility and temperature-dependent behaviors of bio‑carbonation of reactive magnesia (BCRM) technology for soil improvement in cold regions. Unconfined compressive strength tests were conducted to explore the effects of curing temperature (T) and curing age (t) on strength enhancement. Combined with macro- (water content and dry density) and micro- (mineral composition and microstructure) analysis, the underlying mechanisms were elucidated. Experimental results showed that low T retarded the bio‑carbonation reaction of reactive magnesia, resulting in longer t required to obtain stable ultimate strength. However, despite lower increase rates, bio‑carbonized samples achieved higher ultimate strength and secant modulus at lower T. It was primarily attributed to the preferential formation of hydrated magnesia carbonates with higher content and crystallinity at low T, which enhanced the bridging and bonding performance. Comparative analyses with ordinary Portland cement (OPC) highlighted the superior efficiency of BCRM technology in stabilizing soil at low T, showing higher ultimate strength and shorter curing age. Notably at 5 °C, the ultimate strength of the bio‑carbonized sample cured for 12 days was up to 2.94 times that of the OPC-reinforced sample cured for 28 days. This study provides an efficient solution for soil improvement in low-temperature conditions. It is expected to enhance soil stability and hold significant implications for preventing and mitigating geological and geotechnical risks associated with soil deterioration in cold region engineering.

Theoretical insights into the diverse stabilizing effects of fenchyl alcohol/thymol eutectic solvent on carotenoids

Carotenoids, a class of vital natural pigments, are known for their antioxidant properties and are integral to various industrial applications. However, their instability during processing and storage has limited their broader utilization. This study investigated the stabilizing effects of a fenchyl alcohol/thymol-based deep eutectic solvent (DES) on a spectrum of carotenoids, including lutein, zeaxanthin, astaxanthin, and β-carotene. Through a combination of ab initio molecular dynamics (AIMD) simulations and quantum chemical calculations, we elucidated the molecular interactions and stabilization mechanisms within the DES environment (methanol as the benchmark). Our findings reveal that the DES could exert varying degrees of influence on the stability of different types of carotenoids. The temperature-dependent behavior of carotenoids in the DES suggested a complex interplay between hydrogen bonding, dispersion forces, and the inherent structural properties of carotenoids. AIMD simulations provided a detailed picture of the structural organization and hydrogen bond network topology within the DES, highlighting the role of temperature on the stability and orientation of solvent molecules around carotenoids. Energy decomposition analysis (EDA), Hirshfeld surface analysis, and visual study of interactions further dissected the non-covalent interactions, emphasizing the significance of electrostatic and dispersion forces-driven non-covalent interactions (van der Waals dispersion interactions) in stabilizing carotenoids within the DES matrix. In comparison to methanol, the interactions between components of the eutectic system and the target molecules demonstrate enhanced dynamism, increased complementarity, and a greater variety of interaction patterns. This research presented a novel perspective on the use of DESs for the stabilization of carotenoids, offering potential solutions to enhance their industrial applicability and performance. The insights gained from this study are crucial for the development of sustainable and eco-friendly solvent systems, aligning with the growing demand for green chemistry in the pharmaceutical, cosmetic, and food industries.