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Robot-assisted surgery platforms are utilized globally thanks to their stereoscopic vision systems and enhanced functional assistance. However, the necessity of ergonomic improvement for their use by surgeons has been increased. In surgical robots, issues with chronic fatigue exist owing to the fixed posture of the conventional stereo viewer (SV) vision system. A head-mounted display was adopted to alleviate the inconvenience, and a virtual vision platform (VVP) is proposed in this study. The VVP can provide various critical data, including medical images, vital signs, and patient records, in three-dimensional virtual reality space so that users can access medical information simultaneously. An availability of the VVP was investigated based on various user evaluations by surgeons and novices, who executed the given tasks and answered questionnaires. The performances of the SV and VVP were not significantly different; however, the craniovertebral angle of the VVP was 16.35° higher on average than that of the SV. Survey results regarding the VVP were positive; participants indicated that the optimal number of displays was six, preferring the 2 × 3 array. Reflecting the tendencies, the VVP can be a neoconceptual candidate to be customized for medical use, which opens a new prospect in a next-generation surgical robot. [ABSTRACT FROM AUTHOR]

This study investigates the fuel atomization effect of alternating magnetic field (AMF)-based preprocessing equipment that promotes the atomization of automobile fuel. Two coils are connected to the output terminal of the preprocessing equipment and wound on an STS 316 L fuel pipe in the form of a solenoid. Positive sine waves and negative sine waves are output to the two coils, and the AMF in the solenoids causes atomization of the fuel flowing inside the pipe. A spray visualization experiment was conducted with fine particles sprayed from the injector, and the spray arrival distance, spray angle, and spray area were recorded. The information was analyzed to digitize the spray penetration, angle, and area at 2 ms after firing the injector. The fuel atomization effect of the AMF-based preprocessing equipment was also investigated Gasoline was used as the fuel, and the fuel atomization effect was analyzed using the number of windings around the STS 316 L fuel pipe, the frequency applied to the coil, the distance between the two solenoid coils, and the fuel injection pressure as variables. [ABSTRACT FROM AUTHOR]

Biotic ligand models (BLMs) and the sensitivities of indigenous species are used to assess the environmental risk considering the bioavailability of metals, such as nickel. However, the BLM‐based acute–to–chronic ratio (ACR) is required if the predicted no‐effect concentration (PNEC) cannot be derived from the chronic species sensitivity distribution (SSD). The applicability of the ACR approach for estimating BLM‐based PNEC for nickel from acute toxicity data was evaluated in the present study. The BLM‐based acute SSD for nickel was built using the sensitivities of 21 indigenous species and different taxon‐specific BLMs for each taxonomic group. To predict the acute sensitivity of invertebrates, the chronic crustacean nickel BLM with pH effect term, which can account for nickel toxicity at high pH levels, was used. This was used instead of the existing acute BLM for crustacean, which has too narrow a pH range to cover the pH dependency of toxicity. The final BLM‐based ACR of nickel, determined within a factor of 1.53 from the species‐specific acute and chronic sensitivities of the six species, was more reliable than the typical ACR estimated within a factor of 1.84. A linear relationship (r2 = 0.95) was observed between the PNECs using BLM‐based ACR and the PNECs derived from the BLM‐based chronic SSD of the European Union Risk Assessment Reports. In conclusion, the BLM‐based PNEC for nickel could be derived using the ACR approach, unlike when copper BLM was applied. The BLM‐based ACR for nickel is the first result calculated by directly comparing acute and chronic species sensitivities, and will contribute to the application of BLM‐based risk assessment in broader ecoregions. Environ Toxicol Chem 2023;42:914–927. © 2023 SETAC [ABSTRACT FROM AUTHOR]

This study aimed to verify the relationship between ideal sleep duration and physical fitness in South Korean adults and older adults. The secondary analysis data of 2,832 adults (19–64 years) and 629 older adults (65 years and above), obtained from the 2015 National Fitness Survey, were analyzed. Participants completed various physical fitness tests (grip strength, sit-ups, standing long jump, 50 m dash, sit-and-reach, and 20 m shuttle run in adults; grip strength, sit-up, sit-to-stand, sit-and-reach, back-scratch, one-leg standing test, and 6-minute walk in older adults) and were divided into four groups based on self-reported sleep duration. Group differences in physical fitness variables were analyzed with one-way analysis of variance, and Pearson's correlation was used to verify the relationship between sleep duration and physical fitness; statistical significance was set at p <.05. In adult males, there was a positive correlation between explosive muscular strength (standing long jump) and sleep duration (p =.046), whereas in adult females, there was a negative correlation between cardiopulmonary endurance (20 m shuttle run) and sleep duration (p =.026). However, in older adults, there was no significant correlation between sleep duration and physical fitness (p >.05). Further, across the sample, there were no significant group differences in physical fitness variables. A positive correlation exists between sleep duration and muscular strength in adult males and a negative correlation between sleep duration and cardiorespiratory endurance in adult females. Designing sleep and exercise programs based on these results may improve physical fitness among adults and older adults. Future studies that include controlled variables that affect physical fitness and sleep patterns are warranted. [ABSTRACT FROM AUTHOR]

Carbon nanostructures (CNSs) have sparked significant interest in modern science and industry due to their distinct properties and various carbon hybridization states. This makes them appealing for applications, including developing new energy storage devices, filtering systems, catalysts, sensors, and biomedical scaffolds. However, traditional methods' high production costs have prompted researchers to investigate more cost-effective manufacturing techniques. Among these, self-propagating high-temperature synthesis (SHS) has emerged as a promising option, using various carbon-based precursors as feedstock. This manuscript is the first comprehensive attempt to summarize and review a variety of carbon nanostructures synthesized using the SHS method. The review begins with an overview of carbon nanostructure characteristics and fabrication techniques, then delves into the main features of the SHS synthesis method and its suitability for CNS fabrication. It then looks at current approaches for CNS synthesis using the SHS, categorizing them based on the type of carbon precursors used. This analysis includes combustion thermodynamics, adiabatic temperatures and equilibrium phases; experimentally measured combustion temperatures and wave velocities; and combustion reaction chemistry. Simultaneously, we discuss the morphology, phase composition, and other physical-chemical properties of CNS synthesized using SHS. A dedicated section investigates the performance of CNSs in energy storage devices, catalysis, waste adsorption, and polymer reinforcement. Finally, we discuss methodological challenges, opportunities, and future research directions, offering a comprehensive overview of the current state and potential areas for research in this field. [Display omitted] [ABSTRACT FROM AUTHOR]

The synthesis of group IV transition metals (TMs) such as Ti, Zr, and Hf from their respective oxides (TMO 2) poses significant challenges with current methods. There is an urgent need for an environmentally friendly and versatile approach to establish sustainable, efficient, and adaptable TM synthesis technology from TMO 2. In this study, the LN process (Lee-Nersisyan), a novel and straightforward approach that employs CaMg 2 as the reductant for TMO 2 powders is introduced. This innovative strategy involves the thermal processing of TMO 2 + k CaMg 2 mixtures (with k values ranging from 2 to 5 moles) in an argon atmosphere at temperatures between 800 and 1200 °C. The process yields high-purity TM powder with particle sizes in the range of 5–25 μm and oxygen content of less than 0.2 wt%. We apply density-functional theory (DFT) to elucidate the interaction energies and equilibrium interatomic distances between Ti-Ca, Ti-Mg, Ca-Mg, Mg-Mg, Ca-Ca, and Ti-Ti metallic pairs. Additionally, we discuss the growth behavior of TM particles through molecular dynamics simulation (MD) employing LAMMPS. Our LN process represents a promising solution for efficient and sustainable TM synthesis from TMO 2. • An innovative method for producing TM (Ti, Zr, Hf) powders from oxides is presented. • Utilizing CaMg 2 as reductant results TM particles with 0.2 wt% of oxygen is obtained. • Calciothermic reduction of TMO 2 is found to be the primary driving force of reaction. • The interaction energies and interatomic distances of M-M pairs are calculated by DFT. • TM particles sintering and growth behavior based on MD simulation is highlighted. [ABSTRACT FROM AUTHOR]

In this study, we demonstrated the temperature effect of our previously developed topotatic catalysis for the formation of Mn0.005Co2.995O4 (MnCoO) spinel nanoparticles. Topotatic catalysis induces spinel MnCoO nanoparticles through the redox reaction of the metal cation (Co2+ and Mn2+) on the Co(OH)2 nanosheet surface, acting as a growth template. This study particularly elucidates the temperature effect on spinel MnCoO nanoparticles' size, morphology, and crystallinity based on their electrocatalytic performance in an oxygen reduction reaction (ORR). We found that lower temperature produces an amorphous phase, whereas higher temperature induces a large aggregate. We obtained the monodispersed MnCoO nanocubes at approximately 90°C, exhibiting the best ORR performance with an electron‐transfer number of 3.86. [ABSTRACT FROM AUTHOR]

A Mg(II)‐based coordination polymer was synthesized by a solvothermal reaction between Mg2+ and 2,5‐dimercaptoterephthalic acid (H4dmtp) in N,N‐diethylformamide (DEF). The thiol (─SH) groups in the H4dmtp ligand were oxidized to form the sulfinato (─SO2−) groups, which were structurally stabilized through coordination to the Mg2+ centers. The temperature‐dependent proton conductivities exhibited relatively low activation energy (0.19 eV) for proton transfer, suggesting that the hydrogen‐bonded networks formed by the water molecules and the sulfinato oxygen atoms produced efficient proton‐hopping pathways. [ABSTRACT FROM AUTHOR]

Piezoelectric devices such as piezoelectric speaker, motor, and actuator have been actively researched. Accordingly, for developing the ceramics capable of being sintered at low temperature for piezoelectric devices, 0.97(Na0.52K0.443Li0.037)(Nb0.923Sb0.04 Ta0.037)O3 − 0.03(Bi0.5Na0.5)0.9(Sr)0.1ZrO3 ceramics were manufactured according to x (=sintering time) and their piezoelectric and dielectric properties were systematically investigated. At the x = 9 h, the best piezoelectric properties of d33 = 244.33pC/N εr = 1475, and kp = 0.441 were appeared, respectively, for piezoelectric devices. [ABSTRACT FROM AUTHOR]

Recent developments have seen breakthroughs in zero-, one-, two-, and three-dimensional AlN micro- and nanostructures, such as nanoparticles, nanowires, nanotubes, thin films and 3D multifold symmetry crystals. The attractive electrical, optical, and thermal properties of AlN make these materials irreplaceable for microelectrochemical systems (MEMS), surface acoustic waves (SAWs) and light emitting diodes (LED). The significant interest in the field of AlN nanostructure synthesis and application encouraged us to summarise the reported data to better understand the physical and chemical aspects of AlN crystal growth processes. Four main topics are covered in this review article: (1) the morphological diversity of AlN nano- and microstructures; (2) formation mechanisms and growth dynamics; (3) theoretical simulation of growth processes based on density functional theory (DFT) and phase field (PF) modelling approaches; (4) application and devices. This article also provides a perspective on future research relevant to AlN micro- and nanostructures. [ABSTRACT FROM AUTHOR]

We developed a topotatic growth method involving an exfoliated cobalt hydroxide nanosheet, which allows water-based mild reaction conditions (90 °C) for the formation of the homogeneous cubic structure of MnxCo3−xO4 spinel oxides with Mn(II)/Co(II) salts. The size of the nanocubes increased as the Mn content increased, e.g., 13 nm (x = 0.0), 23 nm (x = 0.005), 50 nm (x = 0.05), and 140 nm (x = 1.0). The incorporation of Mn into Co3O4 dramatically increased the ORR performance because the catalytically active Mn cations exclusively substitute the less active Co2+ in the MnxCo3−xO4 structure. We effectively reduced the Mn content in the spinel Co3O4 structure to a value of 0.005, representing the Mn0.005Co2.995O4 spinel nanocubes that unexpectedly exhibited the best ORR activity among the samples. In addition, the XPS and ICP characterizations suggest an Mn-rich shell/Co-rich core for the MnxCo3−xO4 nanocubes. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Daily intakes of PFASs on individual basis by multiple exposure sources are reported. • PFASs in dust showed most significant correlation with PFASs in serum. • Food ingestion was the main contributor of PFASs intake to human. • Indirect dust ingestion was the second contributor of PFASs intake to human. • Individual-based intake of PFASs was higher than the intake on group/scenario basis. Abstract Individual exposure of perfluoroalkyl substances (PFASs) was assessed by analyzing serum, food, dust, drinking water, and hand wipes from 50 individuals. The PFASs concentrations in serum were correlated most strongly with exposure to PFASs through the (direct and indirect) ingestion of dust (p < 0.01). Daily PFOA intakes were estimated to be 2.07 ng/kg/day from food, 0.003 ng/kg/day from dust, 0.053 ng/kg/day from hand-to-mouth activity, and 0.020 ng/kg/day from drinking water. Daily perfluorooctanesulfonic acid (PFOS) intakes were estimated to be 0.689 ng/kg/day from food, 0.001 ng/kg/day from dust, 0.018 ng/kg/day from hand-to-mouth activity, and 0.005 ng/kg/day from drinking water. The daily PFOA and PFOS intakes calculated for individuals in this study and in group/scenario based exposure assessment of previous studies were compared. The estimated PFOS intake on individual basis (0.695 ng/kg/day) was a little bit higher than the intake on group/scenario basis (0.652 ng/kg/day). However, the estimated daily PFOA intake on individual basis (1.41 ng/kg/day) was about four times higher than the intake on group/scenario basis (0.339 ng/kg/day). Among the exposure pathways, food ingestion was major contributor to the total daily PFOA and PFOS intakes on individuals (99% of total intake) and group/scenario basis (64% of total intake). [ABSTRACT FROM AUTHOR]

Ammonia is deemed one of the most important pollutants in the freshwater environment because of its highly toxic nature and ubiquity in surface water. This study thus aims to derive the criteria for ammonia in freshwater to protect aquatic life because there are no water quality criteria for ammonia in Korea. Short-term lethal tests were conducted to perform the species sensitivity distribution (SSD) method. This method is widely used in ecological risk assessment to determine the chemical concentrations to protect aquatic species. Based on the species sensitivity distribution method using Korean indigenous aquatic biota, the hazardous concentration for 5% of biological species (HC 5 ) value calculated in this study was 44 mg/L as total ammonia nitrogen (TAN). The value of the assessment factor was set at 2. Consequently, the criteria for ammonia were derived as 22 mg/L at pH 7 and 20 °C. When the derived value was applied to the monitoring data nationwide, 0.51%, 0.09%, 0.18%, 0.20%, and 0.35% of the monitoring sites in Han River, Nakdong River, Geum River, Youngsan River, and lakes throughout the nation, respectively, exceeded this criteria. The Ministry of Environment in Korea has been considering introducing water quality standard of ammonia for protecting aquatic life. Therefore, our results can provide the basis for introducing the ammonia standard in Korea. [ABSTRACT FROM AUTHOR]

The combustion phenomenon is characterized by rapid self-sustaining reactions, which can occur in the solid, liquid, or gas phase. Specific types of these reactions are used to produce valuable materials by different combustion synthesis (CS) routes. In this article, all three CS approaches, i.e. solid-phase, solution, and gas-phase flame, are reviewed to demonstrate their attractiveness for fabrication of zero-, one-, two-, and three-dimensional nanostructures of a large variety of inorganic compounds. The review involves five sections. First, a brief classification of combustion synthesis methods is given along with the scope of the article. Second, the state of art in the field of solid-phase combustion synthesis is described. Special attention is paid to the relationships between combustion parameters and structure/properties of the produced nanomaterials. The third and fourth sections describe details for controlling material structures through solution combustion synthesis and gas-phase flame synthesis, respectively. A variety of properties (e.g., thermal, electronic, electrochemical, and catalytic) associated with different types of CS nanoscale materials are discussed. The conclusion focuses on the most promising directions for future research in the field of advanced nanomaterial combustion synthesis. [ABSTRACT FROM AUTHOR]

We have developed a simple and facile method to fabricate gold nanoparticles (Au NPs) deposited on thin films of layered double hydroxide (LDH) nanocrystals. The oriented thin film of LDH nanocrystals was employed for the preferential deposition of Au NPs by in situ growth of Au NPs on the monolayer thin film of LDH nanocrystals, which effectively provided a large and uniform active hydroxide surface for deposition of a dense monolayer of Au NPs. The reactive hydroxide groups and the positive potential of the LDH surfaces play an important role in the uniform growth of the Au NPs and in their stabilization against agglomeration. This LDH-supported Au NP catalyst exhibits superior catalytic efficiency and reusability without significant loss in conversion efficiency for the reduction of p-nitrophenol with NaBH4, maintaining more than 96 % catalytic conversion efficiency. [ABSTRACT FROM AUTHOR]

The article presents a study on electrochemical properties of gold nanoparticles (Au NPs) and its electrocatalytics activity for glucose oxidation. Topics discussed include use of electrochemical oxidation of glucose for applications in glucose-oxygen fuel cells and in glucose sensors, optical properties of the nanocomposite of Au NPs and layered double hydroxide (LDH) nanosheet, and development of Au NPs and exfoliated LDH nanosheet by chemical reduction with sodium borohydride (NaBH4).

Age estimation is important in forensics, and numerous techniques have been investigated to estimate age based on various parts of the body. Among them, dental tissue is considered reliable for estimating age as it is less influenced by external factors. The advancement in deep learning has led to the development of automatic estimation of age using dental panoramic images. Typically, most of the medical datasets used for model learning are non-uniform in the feature space. This causes the model to be highly influenced by dense feature areas, resulting in adequate estimations; however, relatively poor estimations are observed in other areas. An effective solution to address this issue can be pre-dividing the data by age feature and training each regressor to estimate the age for individual features. In this study, we divide the data based on feature clusters obtained from unsupervised learning. The developed model comprises a classification head and multi-regression head, wherein the former predicts the cluster to which the data belong and the latter estimates the age within the predicted cluster. The visualization results show that the model can focus on a clinically meaningful area in each cluster for estimating age. The proposed model outperforms the models without feature clusters by focusing on the differences within the area. The performance improvement is particularly noticeable in the growth and aging periods. Furthermore, the model can adequately estimate the age even for samples with a high probability of classification error as they are located at the border of two feature clusters. • Most of the medical datasets are non-uniform in the feature space. • Non-uniformity causes distortion of the age estimation regressor. • Feature cluster-based age estimation model can resolve the distortion problem. • Classification head predicts the cluster in which the input image was included. • Regression head precisely estimates the age within the predicted cluster. [ABSTRACT FROM AUTHOR]

The intraoperative estimated blood loss (EBL), an essential parameter for perioperative management, has been evaluated by manually weighing blood in gauze and suction bottles, a process both time-consuming and labor-intensive. As the novel EBL prediction platform, we developed an automated deep learning EBL prediction model, utilizing the patch-wise crumpled state (P-W CS) of gauze images with texture analysis. The proposed algorithm was developed using animal data obtained from a porcine experiment and validated on human intraoperative data prospectively collected from 102 laparoscopic gastric cancer surgeries. The EBL prediction model involves gauze area detection and subsequent EBL regression based on the detected areas, with each stage optimized through comparative model performance evaluations. The selected gauze detection model demonstrated a sensitivity of 96.5% and a specificity of 98.0%. Based on this detection model, the performance of EBL regression stage models was compared. Comparative evaluations revealed that our P-W CS-based model outperforms others, including one reliant on convolutional neural networks and another analyzing the gauze’s overall crumpled state. The P-W CS-based model achieved a mean absolute error (MAE) of 0.25 g and a mean absolute percentage error (MAPE) of 7.26% in EBL regression. Additionally, per-patient assessment yielded an MAE of 0.58 g, indicating errors < 1 g/patient. In conclusion, our algorithm provides an objective standard and streamlined approach for EBL estimation during surgery without the need for perioperative approximation and additional tasks by humans. The robust performance of the model across varied surgical conditions emphasizes its clinical potential for real-world application. [ABSTRACT FROM AUTHOR]

[Display omitted] • Catalyst membrane for continuous-flow reaction. • Hybrid based on layered double hydroxide and gold nanoparticles. • Porous nanocomposite catalyst for fast and convenient catalysis. • Hydrangea-like porous LDH for dense decoration of gold nanoparticle. • Reusable hybrid porous clay-gold catalyst developed. We synthesized the hybrid catalyst of a porous layered double hydroxide (LDH) decorated with ultrasmall Au nanoparticles. The porous LDH was prepared by coprecipitation and ethanol washing, producing thin LDH nanoplatelets. Thereafter, spray drying was carried out, affording a few hundred nm of the hydrangea-like structure of the LDH with an extensive open network and a Brunauer–Emmett–Teller surface area of 386 m2/g. Its sizable open frame and active hydroxide surface enabled the uniform decoration of average 4-nm-diameter Au nanoparticles (Au/P-LDH) through one-pot chemical reduction using NaBH 4 at room temperature. We applied the Au/P-LDH for the fabrication of catalyst membranes, which are potentially valuable for the continuous flow of catalytic reactions, e.g., the hydrogenation of p-nitrophenol. This study suggested that their porous structure and active Au nanoparticle catalyst allowed fast and mass catalytic functions by simple filtration without washing or catalyst recovery steps. We found no significant damage to the hybrid membrane during the reactions with a few liters; thus, we expect strong bindings of the Au nanoparticles on the surface of the porous LDH. [ABSTRACT FROM AUTHOR]

The copper (Cu) biotic ligand model (BLM) has been used for ecological risk assessment by taking into account the bioavailability of Cu in freshwater. The Cu BLM requires data for many water chemistry variables, such as pH, major cations, and dissolved organic carbon, which can be difficult to obtain from water quality monitoring programs. To develop an optimized predicted no‐effect concentration (PNEC) estimation model based on an available monitoring dataset, we proposed an initial model that considers all BLM variables, a second model that requires variables excluding alkalinity, and a third model using electrical conductivity as a surrogate for the major cations and alkalinity. Furthermore, deep neural network (DNN) models have been used to predict the nonlinear relationships between the PNEC (outcome variable) and the required input variables (explanatory variables). The predictive capacity of DNN models was compared with the results of other existing PNEC estimation tools using a look‐up table and multiple linear and multivariate polynomial regression methods. Three DNN models, using different input variables, provided better predictions of the Cu PNECs compared with the existing tools for the following four test datasets: Korean, United States, Swedish, and Belgian freshwaters. Consequently, it is expected that Cu BLM–based risk assessment can be applied to various monitoring datasets, and that the most applicable model among the three different types of DNN models could be selected according to data availability for a given monitoring database. Environ Toxicol Chem 2023;42:2271–2283. © 2023 SETAC [ABSTRACT FROM AUTHOR]

The hot corrosion behaviors of Inconel alloys with different Cr contents (Inconel 600, 601, and 690), which are used widely in nuclear plants, were investigated in molten LiCl–Li2O salts. The hot corrosion behaviors were studied by measuring the mass and attack depth changes, surface and cross-sectional morphologies and elemental distributions, and compositional changes at the subscale and substrate scale as well as the spalled oxide scale. At 288 h, the weight losses of Inconel 601 and Inconel 690 were approximately four and twelve times higher, respectively, than that of Inconel 600. The corrosion products of all tested alloys were Cr2O3, NiO, and FeCr2O4. Inconel 600, which exhibited a dense and continuous external corrosion layer and an internal corrosion layer with localized corrosion behavior, exhibited superior corrosion resistance compared with those of Inconel 601 and 690, which showed a spalled external corrosion layer and an internal corrosion layer with uniform corrosion behavior. Thus, the corrosion resistance of the Inconel alloys tested in the hot lithium molten salts in an oxidizing atmosphere is closely related to the contents of the primary alloying elements in the alloys. Of the various alloys analyzed in this study, Inconel 600 exhibited the highest corrosion resistance. Thus, a Cr content of 16.30 wt% or less, Ni content of at least 73.66 wt%, and Fe content considerably lower than 8.15 wt% can result in excellent corrosion resistance. [ABSTRACT FROM AUTHOR]

A highly effective way to produce an oxygen reduction electrocatalyst was developed through the self‐assembly of exfoliated single layers of cobalt hydroxide (Co(OH)2) and graphene oxide (GO). These 2D materials have complete contact with one another because of their physical flexibility and the electrostatic attraction between negatively charged GO and positively charged Co(OH)2 layers. The strong coupling induces transformation of the Co(OH)2 single layer into a discrete nanocrystal of spinel Co3O4 with an average size of 8 nm on reduced GO (RGO) during calcination, which could not be obtained with bulk‐layered cobalt hydroxide because of its rapid layer collapse. The ultrafine Co3O4/RGO hybrid exhibited not only comparable performance in the oxygen reduction reaction but also higher durability compared with the commercial 20 wt % Pt/C catalyst. [ABSTRACT FROM AUTHOR]

In this study, tantalum network nanoparticles are prepared from a Ta 2 O 5 + k Mg system via a liquid magnesium-controlled combustion reaction. Super-stoichiometric amounts of magnesium are used in the preparation of a reaction mixture to produce a liquid magnesium pool capable of lowering the combustion temperature and leading to the formation of Ta network structures. The heat transfer kinetics from the hot reaction zone of 'cold' Mg particles is determined using heat transfer-coupled fluid dynamics simulation software. The formation of network structures is characterized through SEM, TEM, XRD, and BET analysis techniques. The mechanism of network formation is explained based on solid particle collisions in liquid media. Our method is able to produce Ta network structures in which the size of individual particles ranges between 50 and 700 nm. [ABSTRACT FROM AUTHOR]

The concentrations of 17 perfluoroalkyl substances (PFASs) were investigated in paddy soil, void water, and brown rice collected from 30 paddy fields to examine the uptake of PFASs from soil by rice. The total concentrations of PFASs ranged from 7.76 to 3020 ng/L (average = 166 ng/L) in void water, 0.120 to 13.9 ng/g dry-weight (dw) (1.92 ng/g dw) in paddy soils, and from not-detected to 1.85 ng/g (0.403 ng/g) in brown rice samples. The highest PFAS concentrations were observed in brown rice cultivated in a paddy field where high levels of PFASs were observed in void water and paddy soil. Among target PFAS compounds, perfluorocarboxylic acids were dominant and detected in all matrices, and perfluorooctanoic acid (PFOA) was the most predominant compound in brown rice and void water. Significant positive correlations were examined for some detected PFASs between each matrix. PFOA in brown rice was positively correlated with PFOA in void water as well as perfluorodecanoic acid (PFDA) in paddy soil (p < 0.01). PFOA in void water also had correlated with PFDA in paddy soil. However, there was no correlation of other compounds between each matrix, except for correlations of perfluorononanoic acid (PFNA) and PFDA in paddy soil with those in void water, respectively (p < 0.05). Moreover, PFOA concentration in brown rice (0.093 ng/g) was much higher than one in white rice detected with a non-detectable level. Unlabelled Image • PFASs were analyzed in paddy soil, void water and brown rice to examine rice uptake. • PFDA in paddy soil showed a positive correlation with PFDA and PFOA in void water. • PFOA in brown rice was correlated with PFOA in void water and PFDA in paddy soil. [ABSTRACT FROM AUTHOR]

As an alternative to wet processing, pyroprocessing shows promise in recycling transuranic elements with high proliferation resistance. The ceramic crucible used in the electrowinning process is a critical issue encountered in pyroprocessing. These ceramic crucibles are frequently damaged by thermal stress and chemical reaction, which results in significant volumes of crucible waste that must be properly disposed. The volume of generated radioactive waste is a concern when dealing with nuclear power plants and decontamination issues. In this study, a chemically stable Sc 2 O 3 crucible was developed, based on thermodynamic calculations, and sintered using a LiCl–KCl electrowinning system. Secondary ion mass spectroscopy was used to measure the intrusion depth of Li in the sintered ceramics. X-ray diffraction was used to measure the reactivity with ceramic and liquid Li. [ABSTRACT FROM AUTHOR]

The waste salt treatment process is required for the reuse of purified salts, and for the disposal of the fission products contained in waste salt during pyroprocessing. As an alternative to existing fission product separation methods, the horizontal zone refining process is used in this study for the purification of waste salt. In order to evaluate the purification ability of the process, three-dimensional simulation is conducted, considering heat transfer, melt flow, and mass transfer. Impurity distributions and decontamination factors are calculated as a function of the heater traverse rate, by applying a subroutine and the equilibrium segregation coefficient derived from the effective segregation coefficients. For multipass cases, 1d solutions and the effective segregation coefficient obtained from three-dimensional simulation are used. In the present study, the topic is not dealing with crystal growth, but the numerical technique used is nearly the same since the zone refining technique was just introduced in the treatment of waste salt from nuclear power industry because of its merit of simplicity and refining ability. So this study can show a new application of single crystal growth techniques to other fields, by taking advantage of the zone refining multipass possibility. The final goal is to achieve the same high degree of decontamination in the waste salt as in zone freezing (or reverse Bridgman) method. [ABSTRACT FROM AUTHOR]

Pyroprocessing has shown promise as an alternative to wet processing for the recycling of transuranics with a high proliferation resistance. However, a critical issue for pyroprocessing is the ceramic crucibles used in the electrowinning process. These ceramic crucibles are frequently damaged by thermal stress, which results in significant volumes of crucible waste that must be properly disposed. Transuranic waste (TRU) elements intrude throughout the pores of a damaged crucible. The volume of generated radioactive waste is a concern when dealing with nuclear power plants and decontamination issues. In this study, laser treatment and sintering were performed on the crucibles to minimize the TRU elements trapped within. Secondary ion mass spectroscopy was used to measure the intrusion depth of Li in the surface-treated ceramics. [ABSTRACT FROM AUTHOR]

We synthesized binder-free Co(OH)2 nanocrystals on nickel electrodes by the ammonia transfer method in an aqueous solution and kinetically-controlled their thickness and height to enhance the capacitance through the facile diffusion of electrolytes in the nanocrystals. As thinner Co(OH)2 films were developed, the specific capacitance increased up to 1260 F g−1 at a current density of 10 A g−1. A thin layer of graphene oxide (GO) was used to wrap the Co(OH)2 nanocrystals to create a pseudocapacitor with high specific capacitance and good cyclic stability. This synthetic strategy enabled us to maximize the electrochemical cell performance, reaching a specific capacitance of 2710 F g−1 under 10 A g−1. The GO coating provides an effective method to increase adhesion on the nickel electrodes and to reduce the decomposition of Co(OH)2 during the charge–discharge process under high pH conditions. The prepared GO/Co(OH)2 nanocomposite layers provided not only high electron mobility but also ionic conductivity, especially when operated at a high current density. [ABSTRACT FROM AUTHOR]

RATIONALE: Quantifying polymers by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) with a conventional crystalline matrix generally suffers from poor sample-to-sample or shot-toshot reproducibility. An ionic-liquid matrix has been demonstrated to mitigate these reproducibility issues by providing a homogeneous sample surface, which is useful for quantifying polymers. In the present study, we evaluated the use of an ionic liquid matrix, i.e., 1-methylimidazolium α-cyano-4-hydroxycinnamate (1-MeIm-CHCA), to quantify polyhexamethylene guanidine (PHMG) samples that impose a critical health hazard when inhaled in the form of droplets. METHODS: MALDI-TOF mass spectra were acquired for PHMG oligomers using a variety of ionic-liquid matrices including 1-MeIm-CHCA. Calibration curves were constructed by plotting the sum of the PHMG oligomer peak areas versus PHMG sample concentration with a variety of peptide internal standards. RESULTS: Compared with the conventional crystalline matrix, the 1-MeIm-CHCA ionic-liquid matrix had much better reproducibility (lower standard deviations). Furthermore, by using an internal peptide standard, good linear calibration plots could be obtained over a range of PMHG concentrations of at least 4 orders of magnitude. CONCLUSIONS: This study successfully demonstrated that PHMG samples can be quantitatively characterized by MALDI-TOFMS with an ionic-liquid matrix and an internal standard. [ABSTRACT FROM AUTHOR]

Nanocomposites based on biomaterials are promising candidates for emerging green‐ electronics benefiting from environment‐friendly, renewable, biocompatible, and biodegradable resources for sustainable research and development. Especially, the application of biocomposites‐based memristor for simulating artificial synapses called bio‐memristor has further facilitated the progress of ecologically benign bioelectronics. In this study, the authors present that the environment‐friendly nanocomposites films, consisting of Ag nanoparticles and cellulose nanocrystal (CNC)‐based bio‐memristor with excellent bipolar resistive switching behavior can perform the artificial bio‐synaptic emulation with continuous resistance modulation for memory storage and neuromorphic computing applications. The bio‐memristor exhibits a large resistive switching (ION/OFF as high as ≈104 and ultralow SET/RESET voltage of ≈0.2 V) and reliable switching characteristics through the electrochemical formation/rupture of Ag metallic filaments within the nanocomposite layer. The device presents coexistence of digital and analog switching properties favorable for both nonvolatile digital memory and neuromorphic computing applications. By applying appropriate pulse stimulations to the device, the authors demonstrate biological synaptic functions, including long‐term potentiation/depression, spike‐rate‐dependent plasticity, excitatory post‐synaptic current, paired‐pulse facilitation, and paired‐pulse depression. Thus, this CNC‐based bio‐memristor as an effective artificial synaptic device is beneficial towards the realization of green‐electronics and bio‐inspired neuromorphic systems. [ABSTRACT FROM AUTHOR]

• Fabricated porous structure in p-type Cu 0.07 Bi 0.5 Sb 1.5 Te 3 compounds by assisting PVA as pore former and studied TE properties. • Lattice thermal conductivity effectively decreased by ~ 38% due to intensified phonon scattering at microscale pores. • The maximum ZT of 1.342 at 400 K and η max of ~ 9.4% at ∆T = 200 K was obtained for the sample with porosity of 10.58%. • The hardness and compressive strength of porous bulks show significantly higher than commercial zone melting materials. [Display omitted] In the background of enhancing thermoelectric (TE) figure of merit of solid-state materials, the introduction of porous structure can significantly decrease lattice thermal conductivity by intensifying phonon scattering at the inhomogeneous microscale pores. Herein, we developed a porous structure in Cu 0.07 Bi 0.5 Sb 1.5 Te 3 compounds by utilizing PVA as the pore former, and systematically studied its effect on thermoelectric properties. The results revealed that the reduction in thermal conductivity (~28%) was greater than the decrease in electrical conductivity (~17%) with increasing porosity, indicating long-wavelength phonon scattering was enhanced at micro-scale pores. Consequently, a peak zT of 1.342 at 400 K, and a zT avg of 1.254 in the temperature range of 300–500 K and an η max of ~9.4% at ΔT = 200 K were achieved in the porous sample (10.58%), which all are higher than that of dense sample. The hardness and compressive strength of the porous samples were significantly higher than commercial zone melting ingots. The proposed methodology is a cost-effective and efficient way of producing high-performance TE devices with good mechanical stability for real life practical applications. [ABSTRACT FROM AUTHOR]

Thousands of radiation portal monitors (RPMs) have been deployed around the world to detect radioactive materials that are outside of regulatory control. The detection capability of the RPMs can be evaluated by conducting a field test with various radioactive materials. However, field tests are limited because the RPMs are operated 24 h a day. The Monte Carlo N-Particle (MCNP) transport code provides an alternative. To evaluate the performance of the RPM with MCNP-based simulation model, the simulation results should be experimentally validated and the measurement result for the validation should be corrected for dead time effect. In this study, an MCNP-based RPM simulation model was developed and the accuracy of the RPM simulation model was improved by correcting dead-time effect. Static and dynamic measurements were conducted and the dead-time correction for the measurement data was factored in. With the static measurement data, the simulation model was developed and the comparing results with the static measurement data show that it satisfied an average relative difference of less than 10%. The simulation model was validated with 17 dynamic measurement datasets and the validation results show that the average relative differences are also within 10% even though the experimental conditions of the static and dynamic measurements were different. • A simulation model of radiation portal monitor was precisely constructed. • Counting losses of measurement data were corrected. • The modified simulation model satisfies 10% of errors with static measurement data. • Validation of the model with dynamic measurement data satisfies 10% of errors. [ABSTRACT FROM AUTHOR]

In this study, the isothermal and cyclic corrosion behaviours of Haynes 282 and Haynes 214 in a lithium molten salt were investigated at 650°C for 168 h and 7 thermal cycles, respectively; this was achieved by measuring the mass changes, surface and cross-sectional morphologies with their elemental distributions, and compositional changes in the subscale, substrate and spalled oxide scale. The weight loss of Haynes 282 comprising an external corrosion layer was approximately four times lower than that of Haynes 214 with a spalled external corrosion layer, depending on the effects of their alloying elements and the preservation, spallation and dissolution of the corrosion layer. After 168 h and 7 thermal cycles, corrosion products of Haynes 282 were Cr2O3 and CoCr2O4 and those of Haynes 214 were Cr2O3, LiFeO2 and FeCr2O4. In addition, the internal corrosion layers of Haynes 282 and Haynes 214 exhibited localised and uniform corrosion behaviours, respectively. [ABSTRACT FROM AUTHOR]

The fabrication of high-quality metallic powders has been attracted considerable attention in terms of producing advanced materials through additive manufacturing (AM) technology. The efficiency of AM products mainly dependent on the initial powder, therefore, characterisation of pre-alloyed powders become important. In this study, we explored the fabrication of Al0.5CoCrFeMnNi high-entropy alloy (HEA) powders by gas atomisation process and investigated their powder characteristics according to particle size distribution. X-ray diffraction results revealed the formation of major face-centred cubic and minor body-centred cubic phase by the addition of Al content. The detailed characterisations such as scanning electron microscopy, Auger electron spectroscopy and XPS analysis was carried out to examine the chemical composition of HEA powders. The relationship between secondary dendrite arm spacing and cooling rate was evaluated. The results demonstrated that produced alloy powders are spherical in shape with smooth surfaces, compositional homogeneity, indicating the gas-atomised powders are widely acceptable for additive manufacturing applications. [ABSTRACT FROM AUTHOR]

The porous nanocomposite of layered double hydroxide (LDH) nanosheets and naturally abundant chitosan biopolymer was developed for facile uptake and selective release of cosmetic liposome capsules (50–200 nm). This study investigated the calcination-reconstruction method to obtain a well-organized and porous LDH/chitosan polymer structure. We used BET analysis and confocal fluorescence microscopy images to show the porous structure and anion-acceptable LDH surface of the nanocomposite. The nanocomposite exhibited a 64.4 m2/g BET surface area, which is eight times higher than commercial LDH particles. These properties allow for facile uptake and controlled release of large liposome particles, depending on the solution pH and anions. This result suggests that the nanocomposite polymer network effectively blocks liposome release. Moreover, we successfully reused collected nanocomposites several times after washing with ethanol to remove residual liposomes. [Display omitted] • Nanocomposite delivery system for cosmetic ingredients. • Hybrid based on layered double hydroxide nanosheets and chitosan. • Porous nanocomposite for large liposome capture. • LDH properties for pH and anion selective release. • Reusable hybrid carrier developed. [ABSTRACT FROM AUTHOR]

Cubic MnxCo3−xO4 (x = 0–0.5) spinel nanocrystal thin films were fabricated on carbon fibre electrodes via one-step topotactic catalysis using Co(OH)2 nanosheets under aqueous and mild reaction conditions (<120 °C). The MnCo3O4 (Mn = 0.01)/CFP catalyst showed the best charge transport efficiency, exhibiting excellent OER activity and stability. [ABSTRACT FROM AUTHOR]

This study investigates two-dimensional REB 6 nanostructures formation from a reaction mixture of RE 2 O 3 –B 2 O 3 –Mg–NaCl composition (RE is Ce, La, Nd, or Eu). The reaction mixture is sealed in a metal cup and is preliminarily heated in argon to reach the flash point. A combustion wave forms on the top surface of the pellet after self-ignition at ~650 °C. This wave quickly propagates through the sample and increases the sample temperature to 800–950 °C, converting the raw mixture into the final product. Processing of the final product leads to the formation of pure hexaboride phases of RE, the particles of which are in the form of nanosheets with a thickness of 50 nm (or less) and a BET surface of 23.8–50.8 m2/g. In addition, CeB 6 nanosheets were tested as a catalyst in NaAlH 4 dehydrogenation/hydrogenation processes. The results demonstrated that the catalytic activity of CeB 6 nanosheets increases with higher portions of NaCl. [ABSTRACT FROM AUTHOR]

The high-temperature corrosion behavior of anode current collectors in liquid Ag under an oxidizing atmosphere was investigated. The weight gain in oxygen was higher than that of liquid Ag because of the effective barrier formed by Ag-rich layer coated on the corrosion layer. The thickness of the corrosion layer under oxygen was approximately twice that of the layer developed under liquid Ag because of the effective barrier originating from the Ag-rich layer. The corrosion products on the surface of the specimens in both oxygen and liquid Ag were Al2O3 and FeAl2O4 from 24 to 168 h. The surface morphology that was developed on the scale of the corroded layer represented a buckle structure in liquid Ag and a convoluted structure in oxygen, which resulted from the lateral growth of the oxide. This study proved the improved stability and cost-effectiveness of using FeCrAl alloy as a current collector in a solid oxide membrane system. [ABSTRACT FROM AUTHOR]

The electroreduction of indium tin oxide (ITO) using a solid oxide membrane anode was investigated in a molten salt of CaF 2 –NaF–CaO at 1150 °C under an inert atmosphere. In the CaF 2 –NaF blank salt, the first reduction peak did not change from −0.25 V (vs. W pseudo reference electrode (R. E.)) for the addition of up to 2 wt% CaO, but the second reduction peak was observed at −0.55 V (vs. W pseudo R. E.) in 1 wt% CaO, and −0.4 V (vs. W pseudo R. E.) in 2 wt% CaO. Cyclic voltammetry analysis was carried out using ITO as the cathode, and a reduction peak was observed at +0.31 V (vs. W pseudo R. E.). This is a positive value about 0.24 V greater than the theoretical value, probably arising because of the increase in the oxygen ion activity of CaO. The optimum ITO particle size was determined to be 600–1000 μm considering the maximum reduction efficiency dependent on the sedimentation rate, specific melt droplet growth, and reduced InSn film formation. The formation of an InSn alloy with almost the same mass ratio as the initial ITO was confirmed by combining the results of X-ray diffraction and energy dispersive X-ray spectroscopy analysis. [ABSTRACT FROM AUTHOR]

Highlights • Corrosion mechanism of Ni-Co-based alloys in LiCl-Li 2 O molten salt is proposed. • Weight loss of alloys with low cobalt was less compared to those with high. • High content of Cr caused intergranular corrosion in the corrosion layer. • Excess Cr has a deleterious effect on kinetics during the hot corrosion process. Abstract In this study, hot corrosion behaviours of Haynes 282 (H282), Nimonic 90 (N90), and Haynes HR160 (HR160) in LiCl-Li 2 O molten salt were investigated at 650 °C under argon atmosphere. The corrosion rate was in the order of H282 < N90 < HR160, depending on the morphology and structure of the scale. H282 showed a localised corrosion behaviour, while N90 showed a uniform corrosion behaviour. For HR-160, intergranular corrosion was observed. The high Cr content caused intergranular corrosion in the corrosion layer. Thus, excess Cr has a deleterious effect on the corrosion kinetics during hot corrosion in LiCl-Li 2 O molten salt. [ABSTRACT FROM AUTHOR]

Abstract A lot of efforts being invested into producing efficient thermoelectric devices based on Bi 0.5 Sb 1.5 Te 3 materials for room temperature applications. Key research achievements of these efforts that incorporation of oxide nanoparticles into Bi 0.5 Sb 1.5 Te 3 materials exhibit higher thermoelectric performance in nano-composite form. Here, we prepared Bi 0.5 Sb 1.5 Te 3 nanocomposite incorporated with TeO 2 nanoparticles (NPs) by high energy ball milling and spark plasma sintering, where in-situ Sb 2 O 3 phase and triple functional interfaces were developed. The formation mechanism of in-situ Sb 2 O 3 phase in the Bi 0.5 Sb 1.5 Te 3 /TeO 2 composites was explored by the thermodynamic calculations; microstructural features and material composition in the bulk samples were investigated using high-resolution transmission electron microscopy (HRTEM) coupled with energy dispersive X-ray spectroscopy (EDS). The formation of interfaces between in situ senarmontite Sb 2 O 3 nanophase and Bi 0.5 Sb 1.5 Te 3 matrix causes an enhanced Seebeck coefficient by ∼20% due to increase of carrier energy filtering and significant reduction of thermal conductivity by ∼77% ascribed to intensified phonon scattering or trapping at 350 K. As a result, an improved dimensionless figure of merit (ZT) of 1.07 at 350 K was achieved in a Bi 0.5 Sb 1.5 Te 3 /3 wt%TeO 2 composites. The proposed in-situ reaction and interface formation mechanisms are expected to open the possibility of further increases in ZT. Graphical abstract Image 1 Highlights • Formation of in-situ Sb 2 O 3 phase in the Bi 0.5 Sb 1.5 Te 3 /TeO 2 composites was explored. • Sb 2 O 3 phase is obtained by in-situ reaction of Sb with TeO 2 during milling and SPS. • The Seebeck coefficient was enhanced owing to increase of energy filtering effect. • Thermal conductivity was reduced (77%) due to phonon scattering at interfaces. [ABSTRACT FROM AUTHOR]

Abstract This study investigated the high-temperature stability of CSZ, YSZ, and MSZ specimens in a CaCl 2 -CaF 2 -CaO molten salt at 1200 °C for the application of the materials as oxygen-ion-conducting solid-oxide membrane anodes in the electroreduction process of metal oxides. YSZ exhibited the lowest degradation among the tested specimens in a high-temperature stability test, whereas CSZ showed the highest degradation. The weight loss was not severe with concentrations of CaO up to 10 wt%. CSZ showed peaks for m-ZrO 2 , YSZ showed peaks for t-ZrO 2 and CaZrO 3 , and MSZ showed peaks for t-ZrO 2 and m-ZrO 2 in 0 wt% CaO. In the case of 5 wt% CaO, all specimens exhibited m-ZrO 2 and CaZrO 3 peaks, In the cases of 10 wt% and 20 wt% CaO, CSZ and MSZ showed peaks for CaZrO 3 , and YSZ showed peaks for m-ZrO 2 and CaZrO 3. While CSZ and MSZ became significantly looser as the CaO concentration was increased to 10 wt%, YSZ became significantly denser due to the formation of a protective layer and attack dependent on the solubility of CaO in the molten CaCl 2. In terms of long-term operation, YSZ was demonstrated to possess superior high-temperature stability compared to CSZ and MSZ, and CaO concentrations from 5 wt% to 10 wt% were found to be significantly more stable than other concentrations. Highlights • The degradation mechanism of CSZ, YSZ, and MSZ in CaCl 2 -CaF 2 -CaO molten salt is proposed. • The formation of CaZrO 3 acts as a protective layer. • YSZ shows high degradation resistance to CaCl 2 -CaF 2 molten salt that contains up to 10 wt% of CaO. • In view of long-term operation, YSZ is demonstrated to possess superior high-temperature stability compared to CSZ and MSZ. [ABSTRACT FROM AUTHOR]

Abstract The adiabatic temperatures and equilibrium phases in the FeTiO 3 - α Mg-C(B, Si)- k NaCl system (where α = 0.2–15, k = 0–3) were analyzed to predict the formation of fine powders of titanium compounds from natural ilmenite sand. From the parametric study, the critical variables were identified and optimized for the synthesis of FeTi, TiC, TiB 2 , and TiFeSi 2 under a combustion regime. The experimentally measured temperatures were in good agreement with those predicted from thermochemical calculations in the 900–1800 °C range. The purified products were characterized using X-ray diffraction, transmission electron microscopy, and Raman spectroscopy. The fine powders of titanium compounds were mainly single phase with a purity of at least 95 wt%. Considering the various stages of the synthetic process, a mechanism is proposed to explain how the process of ilmenite recovery occurred. Graphical abstract Image Highlights • Natural ilmenite was used as a precursor for synthesizing Ti compounds. • Combustion temperatures and phases were determined in FeTiO 3 -αMg-C(B, Si)- k NaCl system. • The effect of Mg and NaCl concentration on the combustion temperature was revealed. • The ilmenite was converted into FeTi, TiC, TiB 2, and FeTiSi 2 fine powders. • A reduction pathway in the synthesis of Ti compounds was proposed. [ABSTRACT FROM AUTHOR]

Abstract This paper reports the preparation of Ti microparticles that are angular and spherical in shape through the combustion of a TiO 2 + αCa (where α is moles of Ca) exothermic mixture in an inert atmosphere. The relationship between the combustion parameters and the properties of the resultant Ti particles is discussed with consideration of the effect of Ca concentration. Using excess amounts of Ca in the experiment was effective in modifying the shape of the particles from angular to spherical. The Ti powder was found to be well-dispersed and the diameter of individual particles ranged from 5 µm to 50 µm. Based on the combustion parameters, the activation energy for the redox reaction was calculated as ∼ 138 kJ/mol. This paper discusses the chemistry of the reduction process and highlights the effects of combustion temperature and the amount of liquid calcium on the characteristics of the Ti particles. Graphical abstract The combustion process in TiO 2 + Ca mixture developed a maximum temperature of about 1820 °C and resulted in Ti spherical particles. fx1 [ABSTRACT FROM AUTHOR]

Abstract We developed an attractive combustion approach for synthesizing uniformly shaped AlN dendritic crystals by combustion of Al + 0.1AlF 3 + k Al 2 O 3 powder mixtures in a nitrogen atmosphere. The combustion temperature measured for various k values was between 1650 and 1750 °C and the micro-droplets of Al formed in the beginning stages of the process were enveloped by the solid layers of Al 2 O 3 , and the subsequent multipoint nucleation and crystallization produced morphologically and size uniform dendritic crystals. We proposed a theoretical model for calculating the thickness and the number of Al 2 O 3 layers around of Al microdroplets at known concentration of Al 2 O 3. Depending on the concentration of Al 2 O 3 , these structures were simple stars with six points and stellar dendrites with multiple petals. [ABSTRACT FROM AUTHOR]

Abstract: The high‐temperature stability of YSZ and MSZ specimens was investigated in CaF2–MgF2–MgO molten salt at 1200°C. YSZ was mostly composed of m‐ZrO2 and a small part of YF3 in the early stages. The formation of YF3 was attributed to the chemical reaction between Y2O3 and MgF2, which can lead to the leaching of Y2O3 from YSZ. With an increase in exposure time, the degraded surface was coarser, and considerable amount of cracks, pores, and spallations were formed. Furthermore, no Y2O3 was found up to 120 μm of the YSZ bulk in the early stages. MSZ was composed of t‐ZrO2 after 24 hours. However, the volume fraction of m‐ZrO2 was 72% after 72 hours, and CaZrO3 was formed by the chemical reaction between CaO and ZrO2 after 168 hours. In addition, the volume fraction of m‐ZrO2 was 60% in 2.5 wt% MgO and 49% in 10 wt% MgO. In 5 wt% MgO, CaZrO3 was formed. We demonstrate that the high‐temperature stability of MSZ was better than that of YSZ, and that 10 wt% MgO was much more stable than the other concentrations of MgO. [ABSTRACT FROM AUTHOR]

We have developed a controllable method for high density of ultrafine gold nanoparticles (NP) and their uniform aggregates on exfoliated nanosheet of layered double hydroxide (LDH). The LDH nanosheet effectively supports the growth of ultrafine gold NP because the freshly exfoliated hydroxide prevents the formation of large and irregular aggregation of gold NP. We found that the reduction conditions allowed controlling the sizes and morphologies of gold NP during their growth on LDH layers. Additionally, pre-added ascorbic acid effectively induced a narrow distribution of gold NP during their reduction reactions by NaBH 4 or hydrazine hydrate. This hybrid material exhibited excellent durability and catalytic activity (>99% conversion efficiency) in the reduction of p -nitrophenol. The nanoscopic nature of exfoliated LDH nanosheets affects the catalytic performances of the hybrid catalyst, such as a high positive charge for strong binding to gold NP, and a fresh hydroxide surface for a good dispersion of the hybrid catalyst in reacting solutions. Our method can be very useful to make stable and reusable Au/LDH nanohybrids for a variety of applications. [ABSTRACT FROM AUTHOR]

In this study, a single-step combustion process for the synthesis 1-D, 2-D, and 3-D micro and nanostructures of AlN was developed. The structures were grown by combustion of Al+ k AlF 3 (or ZnF 2 )+ m NH 4 Cl reaction mixture under 4.0 MPa nitrogen atmosphere. Based on experimental data, the growth conditions, morphology, and composition, optical, and thermal properties of AlN micro and nanostructures were determined. The formation of structures was associated with the combustion temperature, liquid and gas-phase reactions, and the type of additives used in the experiments. The new insight, we gleaned from this study may help in the selective growth of AlN micro and nanostructures of different morphology, enhancing their functionality. [ABSTRACT FROM AUTHOR]

In this study, we examined the effect of potassium perchlorate (KClO 4 ) and magnesium hydroxide (Mg(OH) 2 ) additives on the combustion behavior of a ZrO 2  + 2Mg mixture to produce a fine powder of zirconium metal. The results of thermodynamic analysis and experiments imply that nearly 0.04 mol of KClO 4 is needed to initiate a combustion reaction in the ZrO 2  + 2Mg system. As the amount of KClO 4 increases from 0.04 to 0.1 mol, the combustion temperature increases from 1250 to 1850 °C. This results in formation of fine zirconium powder with a typical particle size of less than 5 µm, and with 1.4–2.2 wt% residual oxygen. Subsequent reduction of particle size to 100–500 nm, and oxygen content to <1.0 wt% was achieved by adding Mg(OH) 2 . The as-prepared Zr powder was mixed with nitrocellulose and printed onto 10–100 µm thin-layers to study their burning stability. The wave propagation in a thin layer was on the order of 0.35–30 cm/s, which is suitable for applications requiring localized power generation. [ABSTRACT FROM AUTHOR]

Combustion of inorganic powder mixtures is not only one of the chemical routes of fabrication of advanced inorganic materials but is also drawing attention as a high-temperature process to grow inorganic nanocrystals of various shapes and morphologies. Here, we demonstrate the formation of AlN 3-D structures with diverse morphologies: from 6-fold patterned crystals to multilayer hierarchical structures. We examined the possible chemical mechanisms governing the formation of AlN crystals and the growth behaviour based on FESEM and TEM observations. [ABSTRACT FROM AUTHOR]