Search Results (147)

As a ferrite material with excellent magnetic and dielectric properties, CoFe₂O₄ is in high demand for applications in areas such as wave absorption and magnetic storage. Effective regulation of its nanoscale morphology is central to improving application performance. Conventional synthesis methods often face challenges including poor particle dispersion and irregular morphology, which limit further optimization of material properties. In this study, a combined approach of microwave hydrothermal synthesis and annealing was employed to systematically investigate the effects of hydrothermal temperature, reaction time, and annealing parameters on the morphology and properties of CoFe₂O₄. The samples were characterized using X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and other techniques. Experimental results show that process parameters exert a notable influence on the crystallinity, particle dispersibility, magnetic and wave-absorbing properties of CoFe₂O₄: the sample prepared by microwave hydrothermal treatment at 75 °C for 30 min exhibits relatively better wave-absorbing performance, with a minimum reflection loss of less than −30 dB and an effective absorption bandwidth covering 8~16 GHz; the sample treated at 100 °C for 15 min shows a more balanced magnetic performance, with the saturation magnetization approaching 60 emu/g. The quantitative structure–property relationships of pure-phase CoFe₂O₄ across microwave hydrothermal and post-annealing processes, and achieve stable, reproducible performance enhancements under optimized mild conditions. These results supplement key experimental data for the low-temperature preparation of CoFe₂O₄ and establish a practical, energy-efficient parameter framework for future structural design and process optimization of this important magnetic material. Full article

Linear α-olefins (LAOs) from CO/H₂ represent an attractive non-petroleum route, yet their selective formation over Fe catalysts is often limited by CO₂ formation via water–gas shift (WGS) reaction and by secondary hydrogenation that consumes terminal olefins. In this work, we demonstrate that these competing pathways can be regulated on carbon-nanotube (CNT) supported Fe catalysts by controlling the CNT interfacial oxygen environment through NO treatment or high-temperature annealing and by adjusting the Mn incorporation protocol between co-impregnation and stepwise addition. Under identical reaction conditions at 280 °C and 3.0 MPa with an H₂-to-CO ratio of 1, high-temperature treated CNTs improve olefin preservation and LAO retention compared with NO-treated CNTs. Mn promotion further shifts selectivity toward α-olefins and lowers CO₂ selectivity. At the same Fe-to-Mn ratio, the Mn introduction sequence produces distinct reducibility and CO-binding behaviors that lead to different steady-state oxide and carbide phases. XPS, H₂-TPR, and CO-TPD collectively suggest that CNT pretreatment and the Mn protocol modulate near-surface oxygen speciation, reduction kinetics, and CO adsorption strength. Mössbauer spectroscopy confirms a predominantly χ-Fe₅C₂ population and indicates the presence of ε-Fe₂C in selected samples together with residual oxide and superparamagnetic Fe species. These results highlight the importance of controlling the CNT–metal interface and Mn–Fe proximity to enhance LAO retention under high-temperature CO hydrogenation. Full article

Adjusting the Schottky barrier height is an important approach to enhancing the gas-sensing performance of TiO₂ Schottky sensors. In this study, micro TiO₂ nanotube Schottky sensors were fabricated via magnetron sputtering and anodic oxidation, with their Schottky barrier height adjusted by varying the annealing temperature. The morphology, phase composition, oxygen vacancy concentration, band structure, and Schottky junction of the samples were investigated using SEM, GIXRD, EPR, Hall effect measurements, XPS, I-V curves, and AC impedance. The sensor annealed at 500 °C demonstrated the highest gas-sensing response, outperforming sensors treated at other temperatures by over 100 times. Its response value to 1 ppm H₂ was 242. The annealing temperature significantly affects the TiO₂ phase and oxygen vacancy concentration, resulting in the highest Schottky barrier height in the 500 °C-annealed sensor, which contributes to its superior sensing performance. AC impedance measurements revealed no significant Fermi-level pinning in TiO₂. Based on the gas-sensing mechanism analysis, the response of the TiO₂ sensor can be divided into three regimes: Schottky junction control, TiO₂ resistance control, and co-control. Full article

Topaz is one of the most economically important fluorine-rich nesosilicates, which are predominantly colorless in natural crystals. Hence, the trade relies almost entirely on irradiated blue topaz with an unstable color center, which has been shown to fade over time. The cobalt (Co) diffusion treatment is a stable alternative process for converting colorless topaz to blue by a solid-state diffusion mechanism. To investigate the potential role of Co²⁺ substitution in the formation of the blue layer and the coupled behavior of F/OH dehydroxylation in facilitating this process, systematic diffusion treatments have been successfully conducted and compared. In this study, gem-quality topazes were annealed in air at 1000 °C for 20–40 h (hr) along with CoO, Fe₂O₃, Cr₂O₃, and CuO powders. The diffused products were characterized using Scanning Electron Microscope (SEM), Ultraviolet-Visible absorption spectroscopy (UV-Vis), Near-Mid Infrared spectroscopy (NMIR), and X-ray photoelectron spectroscopy (XPS). Parallel runs with CuO, Fe₂O₃, or Cr₂O₃ alone confirmed that none of these oxides produces a stable blue layer, underscoring the unique role of Co. The Co-diffused sample displays an intense blue layer characterized by a Co²⁺ octahedral isomorphism triplet at 540, 580, and 630 nm, which are absent from both untreated and heat-only controls. XPS analysis reveals the emergence of Co²⁺ (binding energy: 780.63 eV) and a concomitant depletion in F⁻, along with the disappearance of the OH overtone absorption at 7123 cm⁻¹. These observations confirm that defluorination generates octahedral vacancies accommodated by the coupled substitution: CoF₂ (solid reactant) + (AlO₂)⁻ (fragment of topaz structure) → AlOF (solid product) + (CoOF)⁻ (fragment of topaz structure). Prolonged annealing leads to decreased relative atomic percentages of K⁺ and F⁻ ions, consistent with volatilization losses during the high-temperature process, thereby directly correlating color intensity with cobalt valence state, which transfers from Co²⁺ to Co³⁺. These findings establish a Co-incorporation chronometer for F–rich aluminosilicate systems, with an optimal annealing time of approximately 20 hr at 1000 °C. Furthermore, the above results demonstrate that the color mechanism in nesosilicate gems is simultaneously governed by volatile release and cation availability. Full article

This work focuses on developing resistive switching (RS) devices using thermally annealed (TA) SiO₂/Si multilayers (ML). Three SiO₂/Si bilayers were deposited with an additional 10 nm SiO₂ layer as a dielectric barrier layer on top of the ML. The SiO₂ layers were 6 nm thick, while the thickness of the Si layers varied from 2, 4, and 6 nm, and were labeled as ML-62, ML-64, and ML-66, respectively. X-ray photoelectron spectroscopy analysis revealed well-defined ML structures before TA. However, after TA, samples ML-64 and ML-62 showed discontinuities due to diffusion between neighboring Si layers, increasing the dimensions of the Si-rich regions. In fact, the concentration of elemental Si (Si⁰) within the intermediate Si layer increases as the Si layer becomes thinner. Consequently, the size of Si-nanocrystals, created after TA, increases from 6 to 8.5 nm for ML-66 to ML-62, as confirmed by Raman and transmission electron microscopy analysis. The composition discontinuities and loss of the ML structure resulted in erratic electrical behavior, with an electroforming (EF) voltage as high as −14 V in sample ML-62. For the ML-66, which retained the ML structure, the EF voltage was reduced to −4 V, showing SET/RESET values of around ±3 V and stable electrical behavior, with an ON/OFF ratio of up to seven orders of magnitude. This demonstrates the importance of the ML design in the operation of RS devices. Full article

Coating plays an important role in advancing sensing technology by significantly enhancing sensitivity, stability, and response time. The unique properties of nanostructures, including high surface-to-volume ratio and tunable porosity, make them suitable candidates for improving sensor performance. By optimizing nanostructure coatings, advancements in high-precision humidity sensing devices are achievable, enabling a wide range of industrial applications, especially in humidity-controlled industries. In this study, the effects of annealing time, annealing temperature, and the number of coating layers on the properties of additive-enhanced SnO₂ nanostructure were investigated. The experiment was carried out by subjecting the additive-enhanced SnO₂ nanostructure to different annealing times and annealing temperatures to analyze its impact on crystallinity, porosity, and moisture adsorption properties. Upon optimizing the annealing parameters, multilayer coatings were carried out to assess the effect of the total number of coating layers on hygroscopic behavior. A hygroscopicity test was carried out on each sample to evaluate its moisture adsorption and desorption capabilities. The results demonstrated that controlled annealing conditions significantly improve the nanostructure’s hygroscopic properties, and the optimized coating layers further enhanced the moisture retention, making the developed SnO₂ nanostructure a promising candidate for advanced sensing applications. Full article

Even though clinoptilolite mineral is the most important natural zeolite for technical applications, the molecular-level insights and detailed knowledge of their true local structures and adsorption behavior are largely lacking. An experimental determination of their surface structures, in particular, could be very challenging due to the sensitivity of some facets to temperature and impurities. In this study, we present a robust multiscale modeling framework to investigate the adsorption of 5-fluorouracil, an anticancer drug, on dispersion-corrected density functional theory (DFT-D3)-optimized Na-clinoptilolite surfaces. Using a combination of interface force field and polymer consistent force field-based molecular dynamics with simulated annealing and parallel replica sampling, followed by DFT-D3 optimizations, we explore a wide configurational space of surface–molecule interactions. Our results show that Na-clinoptilolite surfaces support very strong adsorption, with adsorption energies ranging from −430.0 to −174.4 kJ/mol. Surface models with exposed Na cations consistently exhibit stronger binding, in contrast to their known steric hindrance effects in bulk environments. Furthermore, cation-free surfaces displayed relatively weaker interactions, yet configurations exposing the 8-membered rings (8 MR) demonstrated more favorable adsorption than those exposing 10 MR channels due to enhanced hydrogen bonding and spatial and entropic confinement effects. These findings reveal the importance of surface composition, local geometry, and configurational sampling in determining adsorption performance and lay the groundwork for future studies on cation-specific and multicationic clinoptilolite systems. Full article

This study investigated the influence of various annealing treatments on the microstructure and corrosion behavior of 20MnCr5 steel in a 3.5% NaCl solution. A combination of microstructural analysis, hardness testing, and electrochemical techniques was used to comprehensively characterize each condition. To enhance data interpretability, a correlation analysis was performed and visualized through a correlation diagram, enabling statistical assessment of the relationships between grain features, phase distribution, mechanical properties, and corrosion indicators. The results demonstrated that corrosion resistance in 20MnCr5 steel is not governed by a single parameter but by the interplay between grain size, morphology, and phase balance. Excessive pearlite content or coarse, irregular grains were consistently associated with higher corrosion rates and lower electrochemical stability. In contrast, a moderate phase ratio and equiaxed grain structure, achieved through normalization, resulted in better corrosion resistance, confirmed by the highest polarization resistance and lowest corrosion current density values among all samples. Although increased grain refinement improved the hardness, it did not always correlate with a better corrosion performance, especially when morphological uniformity was lacking. This highlights the importance of balancing mechanical and corrosion properties through carefully controlled thermal processing. Full article

We studied the influence of annealing on the magnetic properties and microstructure of ultrathin (metallic nucleus diameter ≈ 5 μm, total diameter ≈ 19 μm) Heusler-type NiMnGa glass-coated microwires prepared using the Taylor–Ulitovsky method. The as-prepared NiMnGa microwires exhibit unexpectedly strong magnetic anisotropy, characterized by a coercivity exceeding 3 kOe at room temperature. Furthermore, their Curie temperature (T_c) lies above room temperature. Additionally, a spontaneous exchange bias of approximately 120 Oe is observed in the as-prepared sample at 100 K. Annealing the microwires leads to a decrease in coercivity, spontaneous exchange bias, and T_c values. Notably, the annealing process shifts the T_c of the samples closer to room temperature, making them more suitable for magnetic solid-state refrigeration applications. Moreover, the hysteresis observed in the temperature dependence of magnetization for the samples annealed for 1 h and 2 h, along with the magnetic softening observed at around 260 K, is attributed to a first-order phase transformation. The observed changes are discussed in the context of internal stress relaxation after annealing, the nanocrystalline structure of both the as-prepared and annealed samples, the recrystallization process, and the magnetic ordering of phases identified in the as-prepared sample and those appearing during recrystallization. The glass coating on microwires offers benefits like better flexibility and resistance to damage and corrosion. However, it is important to recognize that this coating can substantially alter the microwires’ magnetic characteristics. Consequently, precise control over the annealing process is vital to obtain the specific martensitic transformation needed. Full article

The gate reliability issues in SiC-based devices with a gate dielectric formed through heat oxidation are important factors limiting their application in power devices. Aluminum oxide (Al₂O₃) and titanium dioxide (TiO₂) were combined using the ALD process to form a composite AlTiO gate dielectric on a 4H-SiC substrate. TDMAT and TMA were the precursors selected and deposited at 200 °C, and the samples were Ar or N₂ annealed at temperatures ranging from 300 °C to 700 °C. An XPS analysis suggested that the AlTiO film had been deposited with a high overall quality and the involvement of Ti atoms had increased the interfacial bonding with the substrate. The as-deposited MOS structure had band shifts of ΔE_C = 1.08 eV and ΔE_V = 2.41 eV. After annealing, the AlTiO bandgap increased by 0.85 eV at most, and better band alignment was attained. Leakage current and breakdown voltage characteristic investigations were conducted after Al electrode deposition. The leakage current density and electrical breakdown field of an MOS capacitor structure with a SiC substrate were ~10⁻³ A/cm² and 6.3 MV/cm, respectively. After the annealing process, both the measures of the JV performance of the MOS capacitor had improved to ~10⁻⁶ A/cm² and 7.2 MV/cm. The interface charge N_eff of the AlTiO layer was 4.019 × 10¹⁰ cm⁻². The AlTiO/SiC structure fabricated in this work proved the feasibility of adjusting the properties of single-component gate dielectric materials using the ALD method, and using a suitable thermal annealing process has great potential to improve the performance of the compound MOS dielectric layer. Full article

Tomato leaf curl New Delhi virus (ToLCNDV) and tomato yellow leaf curl virus (TYLCV) are two important viral pathogens that severely affect Solanaceae and Cucurbitaceae plants. In order to reduce the further spread of these viruses, it is crucial to establish an efficient and reliable method to accurately detect the viruses. In this study, a multiplex PCR assay for the simultaneous detection of TYLCV and ToLCNDV was established. Three primer pairs designed from conserved regions within the coat protein or movement protein-encoding regions of the respective viruses were employed in the assay. The optimization of parameters such as primer concentration was set at 0.15 μM/0.15 μM, 0.25 μM/0.25 μM, and 0.50 μM/0.50 μM for ToLCNDV-DNA-A-F/R, TYLCV-F/R, and ToLCNDV-DNA-B-F/R primer pairs. At optimal primer concentrations, the multiplex PCR method demonstrates effective performance with an annealing temperature ranging from 51 °C to 66 °C. The specificity of the assay evaluated by testing against other begomoviruses showed no evidence of cross-amplification. Further sensitivity analysis performed using a serially diluted plasmid containing viral targets as templates demonstrated high sensitivity with a detection limit of 10³ copies/μL. Field surveys utilizing the multiplex PCR assay successfully identified the infection of TYLCV and ToLCNDV in field-collected samples. Full article

Dynamic relaxations play an important role in understanding the nature of glass. The conventional methods to explore dynamic relaxations rely on the measurement of mechanical and thermic properties, while new methods that may provide a new perspective to probe dynamic relaxation are desperately required. Here, we show that the β-relaxation of metallic glasses (MGs) can be unveiled by electrical resistivity (ER). Irreversible β-relaxation leads to an increment in electrical resistivity, which can be fitted by the Kohlrausch–Williams–Watts equation well. In contrast, the ER results of the initialized sample only exhibit a negligible change during annealing, which indicates that the reversible β-relaxation change cannot be manifested by ER testing. This work provides the ER measurement as a new means to explore the dynamic relaxation of MGs, which may offer a new insight into the understanding of β-relaxation in glass materials. Full article

The microstructure of 40CrMnMoA during hot forging determines its macroscopic mechanical properties. Dynamic recrystallization (DRX) behavior is commonly used to refine grains and improve the microstructure of materials; therefore, it is important to be able to predict mechanical behavior during hot forging and the microstructure evolution during dynamic recrystallization. In order to accurately determine the DRX model parameters of 40CrMnMoA steel, an inverse optimization method is proposed in this work. The uniaxial isothermal compression experiment of 40CrMnMoA steel was carried out on a Gleeble-1500D thermal simulation tester (Dynamic Systems Inc. (DSI), Poestenkill, NY, USA) under the temperature range of 900~1200 °C and the strain rate range of 0.005 to 5 s⁻¹. Based on the true stress–strain data obtained by a compression test, the DRX model of 40CrMnMoA was initially established using the traditional averaging method. Subsequently, the DRX model parameters calculated by the conventional averaging method were used as the initial values, the mean-square error between the experimental and calculated values of the DRX volume fraction was set as the objective function, and the DRX model parameters were optimized by the adaptive simulated annealing (ASA) algorithm. By comparing the correlation coefficient R, average absolute relative error (AARE), and the root mean square error (RMSE) of the predicted DRX percentage with the experimental values before and after optimization, it was found that the optimized model achieved an R-value of 0.992, with AARE and RMSE decreased by 34% and 2%, respectively, which verified the accuracy of the optimized DRX model. Through the program’s secondary development, the optimized DRX model of 40CrMnMoA was integrated into finite element software Forge^® 3.2 to simulate the isothermal compression process. The comparison between grain size from the central region of simulation results and actual samples revealed that the relative error is less than 3%. This result demonstrated that the inverse optimization method can accurately identify the DRX model parameters of 40CrMnMoA alloy steel. Full article

Probabilistic models in physics often require the evaluation of normalized Boltzmann factors, which in turn implies the computation of the partition function Z. Obtaining the exact value of Z, though, becomes a forbiddingly expensive task as the system size increases. A possible way to tackle this problem is to use the Annealed Importance Sampling (AIS) algorithm, which provides a tool to stochastically estimate the partition function of the system. The nature of AIS allows for an efficient and parallel implementation in Restricted Boltzmann Machines (RBMs). In this work, we evaluate the partition function of magnetic spin and spin-like systems mapped into RBMs using AIS. So far, the standard application of the AIS algorithm starts from the uniform probability distribution and uses a large number of Monte Carlo steps to obtain reliable estimations of Z following an annealing process. We show that both the quality of the estimation and the cost of the computation can be significantly improved by using a properly selected mean-field starting probability distribution. We perform a systematic analysis of AIS in both small- and large-sized problems, and compare the results to exact values in problems where these are known. As a result, we propose two successful strategies that work well in all the problems analyzed. We conclude that these are good starting points to estimate the partition function with AIS with a relatively low computational cost. The procedures presented are not linked to any learning process, and therefore do not require a priori knowledge of a training dataset. Full article

Porcine astrovirus (PoAstV), porcine sapovirus (PoSaV), porcine norovirus (PoNoV), and porcine rotavirus A (PoRVA) are newly discovered important porcine diarrhea viruses with a wide range of hosts and zoonotic potential, and their co-infections are often found in pig herds. In this study, the specific primers and probes were designed targeting the ORF1 gene of PoAstV, PoSaV, and PoNoV, and the VP6 gene of PoRVA. The recombinant standard plasmids were constructed, the reaction conditions (concentration of primers and probes, annealing temperature, and reaction cycle) were optimized, and the specificity, sensitivity, and reproducibility were analyzed to establish a quadruplex real-time quantitative RT-PCR (RT-qPCR) assay for the detection of these four diarrheal viruses. The results demonstrated that the assay effectively tested PoAstV, PoSaV, PoNoV, and PoRVA without cross-reactivity with other swine viruses, and had limits of detection (LODs) of 138.001, 135.167, 140.732, and 132.199 (copies/reaction) for PoAstV, PoSaV, PoNoV, and PoRVA, respectively, exhibiting high specificity and sensitivity. Additionally, it displayed good reproducibility, with coefficients of variation (CVs) of 0.09–1.24% for intra-assay and 0.08–1.03% for inter-assay. The 1578 clinical fecal samples from 14 cities in Guangxi Province, China, were analyzed via the developed assay. The results indicated that the clinical samples from Guangxi Province exhibited the prevalence of PoAstV (35.93%, 567/1578), PoSaV (8.37%, 132/1578), PoNoV (2.98%, 47/1578), and PoRVA (14.32%, 226/1578), and had a notable incidence of mixed infections of 18.31% (289/1578). Simultaneously, the 1578 clinical samples were analyzed with the previously established assays, and the coincidence rates of these two approaches exceeded 99.43%. This study developed an efficient and precise diagnostic method for the detection and differentiation of PoAstV, PoSaV, PoNoV, and PoRVA, enabling the successful diagnosis of these four diseases. Full article