Search

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]

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]

Abstract: In this paper, the cumulative risks of Di(2-ethylhexyl) phthalate (DEHP), Di-n-butyl phthalate (DBP), and Benzyl-butyl phthalate (BBP) to 2-year-old children in two countries: one European (Denmark) and one Asian (South Korea) were compared. Denmark does not produce phthalates as a raw material, while Korea produces more than 0.4milliontons of the three above-mentioned phthalates each year. First, a comparative review of the existing phthalate regulations in the two countries was performed. Next, the level of childhood phthalate exposure from environmental and food sources was estimated using an exposure scenario approach. Then, the scenario based exposure level was compared with back-calculated exposure levels based on biomonitored urinary phthalate metabolite concentrations. The result verifies the existence of varying territorial human background exposure levels and the gap between exposure estimations based on exposure modeling and biomonitoring data. Cumulative childhood risk levels in Denmark were lower than in Korea. For both countries, risk levels from back calculation were higher than those from scenario estimation. The median cumulative risk levels from scenario estimation and back calculation respectively were 0.24 and up to 0.5 in Denmark while 0.52 and up to 0.95 in Korea. Food and indoor dust were the main exposure sources for all three phthalates. In order to protect human health from cumulative risks of these phthalates, the exposure scenarios in existing regulations such as the EU REACH need to be strengthened. Moreover, based on the contributions from different exposure sources, national specific risk management tools need to be developed and strengthened, applying a systemic approach to promote sustainable material flows. [Copyright &y& Elsevier]

Abstract: Fetal and maternal exposure levels of two emerging pollutants, polybrominated diephenyl ethers (PBDEs) and synthetic musks, were measured in Korean general population to assess prenatal and postnatal exposures in infants. For this purpose, paired samples of breast milk, maternal and cord blood were collected from 20 Korean women in 2007. In comparison to data from other countries and previous data from Korea, relatively higher and gradually increasing concentrations for PBDEs were found in Korean breast milk (

Quantitative investigation of the shape selectivity for the competitive intercalation reaction of isomeric mixtures in the interlayer of LDH was achieved by analyzing the solid phases synthesized by the reaction of [LiAl2(OH)6]Cl·yH2O with various compositional mixtures of (E,E)- and (Z,Z)-muconates. The apparent partition constant K′ for the anion-exchange reaction between (E,E)- and (Z,Z)-muconates was quite dependent on the mole fraction of muconates in solution. The only single phase saturated with [LiAl2(OH)6]2[(E,E)-C6H4O4]·zH2O could be obtained in the range of the initial mole fraction of (E,E)-muconate larger than 0.6 in the starting solution, while mixed phases intercalated with (E,E)- and (Z,Z)-muconates could be obtained at lower mole fractions of (E,E)-muconate. The shape selectivity for the competitive reaction of two muconates on the [LiAl2(OH)6]+ lattice could be ascribed to thermodynamic processes, and the conditions under which that pure (E,E)-muconate was efficiently separated from isomeric mixtures of two muconates were successfully evaluated. [Copyright &y& Elsevier]

Efficient hydrogen production relies on cost-effective and durable non-noble metal electrocatalysts for the hydrogen evolution reaction (HER). In this work, a liquid metal-assisted solid-flame combustion synthesis (SF-CS) method was used to create transition metal carbide TMC) nanocrystals with exposed facets. The TMCs include TiC, VC, NbC, TaC, Ta 2 C, WC, and Mo 2 C. In acidic solutions, the TMC nanocrystals show enhanced conductivity and superior HER performance, as evidenced by their lower Tafel slope, higher current density, and decreased overpotential. In particular, Mo 2 C nanocrystals exhibit an overpotential of 95 mV and a Tafel slope of 26 mV dec−1. These findings highlight a noteworthy improvement over previously reported nanostructures in recent years in terms of the HER properties of Mo 2 C with particular facets. This improvement is attributed to the unique surface characteristics, such as energy and active sites, which are impacted by various factors and require more investigation to meet the intended goals. [Display omitted] [ABSTRACT FROM AUTHOR]

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]

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]

• 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]

Abstract: This work describes the role of temperature and rolling method on density and microstructure changes in Cu–15% In (wt%) alloy powder during normal and cross-roll rolling. The rolled specimen consisted of two distinct microstructures: α-Cu and Cu7In3 intermetallic compounds. The specimen obtained with 5° of cross rolling degree and 60% of rolling reduction ratio at 600°C has the highest density of 8.812g/cm3. A detailed analysis of these results in terms of the microstructural changes and densification mechanisms is also presented. [Copyright &y& Elsevier]

Abstract: Zirconium-based ceramics and composites such as ZrC, ZrB2, ZrC–SiC, ZrB2–SiC–ZrC, and ZrB2–SiC–ZrC–ZrSi were synthesized in fine powder form via combustion synthesis (CS) using ZrSiO4, Mg, C, B, and NaCl as raw materials. Temperature distributions in the combustion wave were measured by thermocouples and used to estimate the combustion temperature and wave propagation velocity. The influence of the NaCl mole fraction on the combustion parameters, phase composition, and particle size of the composite powders was investigated. The experimental results revealed that the combustion temperature and particle size of the composites have a stable decreasing tendency with increase in the NaCl mole fraction in the starting mixture. It was found that near the combustion limit (1.5mol NaCl), the combustion temperature drops below 1500°C and the particle size reaches the nanometer scale. [Copyright &y& Elsevier]

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]

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 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]

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]

In this study, the isothermal and cyclic corrosion behaviors of custom-made nickel-based alloys (N105, N107, and N108) with various elemental compositions in a LiCl-Li 2 O molten salt were investigated at 650 °C in argon atmosphere. The isothermal and cyclic corrosion behaviors were studied by measuring the mass changes, surface morphologies, cross-sectional morphologies with elemental distribution, and the compositional changes of the subscale and substrate as well as the spalled oxide scale. Under the isothermal and cyclic corrosion test, the corrosion rate was in the order of N108 < N105 < N107, and N107 < N105 < N108, respectively, which depended on the morphology and structure of the crystals formed on the surface of the outer scale in contact with the molten salt, and was also related to the region of Al and Cr depletion. After the isothermal corrosion test, the hot corrosion products formed in N105 were Cr 2 O 3 , NiCr 2 O 4 , and Li 2 Ni 8 O 10 and those in N107 were Cr 2 O 3 and NiCr 2 O 4 , while Cr 2 O 3 , NiCr 2 O 4 , and LiTiO 2 were identified as the hot corrosion products of N108. However, the hot corrosion products of N105, N107, and N108 were Cr 2 O 3 , NiCr 2 O 4 , and LiFeO 2 after the cyclic corrosion test. [ABSTRACT FROM AUTHOR]

In this study, a combustion process for a TiO 2 + 0.12Al + (2.5 + 6 k )Mg + 0.021V 2 O 5 + k MgCl 2 ·6H 2 O mixture was studied to fabricate Ti-6Al-4V alloy spherical particles. From the temperature-time profiles, the average value of the synthesis temperature was estimated to be 1650 ± 20 °C. Based on FESEM observations, spherical shape particles were obtained when 0.05–0.1 mol MgCl 2 ·6H 2 O was added to the initial reaction mixture. Therefore, spherical alloy particles were achieved by consecutive processes of cooling and acid purification of the burned down sample. According to laser particle size analysis, the average diameter of the spheres was between 5 and 25 μm. A selective laser melting process was applied to build dense Ti-6Al-4V alloy samples. The tensile properties and the microhardness were evaluated and compared to those characteristics of a reference sample prepared from commercial Ti-6Al-4V alloy spherical powder. [ABSTRACT FROM AUTHOR]

This study deals with combustion behavior of B 2 O 3 /Mg/NH 4 Cl/C complex systems for the synthesis of amorphous boron (B), boron carbide (B 4 C), and boron nitride (BN) nanostructures. The raw mixtures used in the experiments were prepared on the base of a B 2 O 3 –Mg precursor mixture, which is sufficiently exothermic to maintain a self-propagating regime of the combustion reaction. Thermodynamic analysis of the combustion temperatures and experimental validation indicate that the 1000–1500 °C temperature range is very effective for synthesizing the nanostructures of B, B 4 C, and BN. It was found that B-containing functional nanostructures are mainly spherical nanoparticles (B) or nanosheets (B 4 C, BN). The phase composition and microstructural characteristics of the final products were evaluated based on the combustion temperature and solid/liquid phase changes. [ABSTRACT FROM AUTHOR]

The present investigation studied the recycling of zinc from brass ash which is a secondary product produced during the brass smelting process. A retiring cycle was devised to produce high-purity ZnO nanopowders. Recovery of > 90 wt% of the total zinc available was achieved after the calcination of brass ash at 700 °C and a multistage hydrometallurgical treatment at room temperature. ZnO powder produced by the developed method was analyzed by X-ray diffraction, transmission electron scanning microscopy, ICP-AES and BET analysis. The ZnO nanopowder obtained from the brass ash was well dispersed and the size of the individual particles was in the range of 30–50 nm. The purity of the powder was 99.83 wt%, and the surface area was about 30.5 m 2 /g. A relative density level of about 98.1% was reached with ZnO pellets sintered at 1300 °C. [ABSTRACT FROM AUTHOR]

High-quality two-dimensional (2D) nanosheets of B 4 C were synthesized using a facile combustion reaction with a reaction mixture comprising boron oxide (B 2 O 3 ), magnesium (Mg), and polyvinylchloride (C 2 H 3 Cl) n . The ability to tune the nanosheets of boron carbide was achieved by controlling the combustion temperature within a range of 1500–1700 °C and by using polyvinylchloride powder as the carbon source. FE-SEM and TEM images of the acid leached combustion products show sheet-like B 4 C particles with thicknesses of about 10–50 nm and edge lengths from 0.1 to several micrometers. The chemistry of the combustion process and the formation mechanism of B 4 C nanosheets are discussed based on the experimental findings. [ABSTRACT FROM AUTHOR]

Combustion based synthesis of AlN nanoparticles using the "solid nitrogen" promotion reaction was investigated in Al2O3 + 3Mg system in nitrogen atmosphere. A controlled amount of Mg + 0.5NH4Cl mixture as a solid source of nitrogen was blended with the Al2O3 + 3Mg starting system and the synthesis reaction of AlN nanoparticles was conducted using the exothermic heat of the entire reaction system. The resulting AlN nanoparticles were characterized by X-ray diffraction (XRD), Raman and Fourier transform infrared spectroscopy (FTIR), PL spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy, and Brunauer-Emmett-Teller surface area techniques. The analysis results confirmed that single phase and crystalline AlN nanoparticles with an average size of 50-500 nm were obtained from the developed approach. Photoluminescence spectra of AlN nanopowders under the excitation of 230-270 nm UV light revealed that AlN emits yellow-red light having a wavelength near to 590 nm. The chemistry of the combustion process is discussed and the basic reactions that led to the formation of AlN are presented. [ABSTRACT FROM AUTHOR]

The harsh atmosphere of the sulfur–iodine process used for producing hydrogen requires better corrosion resistance and mechanical properties than are possible to obtain with pure tantalum. Ta–W alloy is superior to pure tantalum but is difficult to alloy due to its high melting temperature. In this study, substrate samples were coated with Ta–W (Ta–7W, Ta–4W and Ta–1W) using the Multi-Anode Reactive alloy Coating (MARC) process in molten salt (LiF–NaF–K 2 TaF 7 ), with varying distances between cathode and anode. In the case of Ta–4W, a corrosion rate of less than 0.011 mm/year was attained in hydriodic acid at 160 °C, and thickness uniformity was 80.3 ± 2.15 μm. Also, the resulting coated films had hardnesses up to 12.9% stronger than pure tantalum coated film. The alloy coating films also contributed to significant enhancement of corrosion resistance. [ABSTRACT FROM AUTHOR]

A melt-assisted solid flame synthesis approach was applied to synthesize boron nanoparticles in argon gas and air atmospheres. For this purpose, we investigated the characteristics of a thermally induced combustion wave in B 2 O 3 + α Mg mixtures ( α = 1.0–1.5 mol) in argon and air atmospheres. Utilizing stoichiometrically insufficient amounts of magnesium ensured that a large portion of molten B 2 O 3 remained in the sample, which reduced the combustion parameters and favored the formation of boron nanoparticles. Under these conditions the combustion temperature and burning velocity were controlled in the range of 1300–1580 °C and 0.065–0.18 cm/s, respectively, and boron nanoparticles in a ∼20–200 nm size range were obtained. The characteristics of boron nanoparticles (morphology, purity, specific surface area, oxidation activity, etc.) were analyzed and a reaction pathway leading to boron nanoparticles synthesis was proposed. [ABSTRACT FROM AUTHOR]

The importance of ZT in thermoelectric (TE) materials is critical for green power generation and cooling applications. Therefore, tremendous efforts were underway to improve ZT, in which we proposed a layer structured approach by successively arranging of coarse Bi 0.5 Sb 1.5 Te 3 (BST) and fine BST/0.07Cu microstructure materials and investigated their transportation mechanism. The dual bulk microstructure was well-bonded and confirmed by analyzing the microstructure through scanning electron microscope (SEM), electron backscatter diffraction analysis (EBSD) and simulated the electrical potential and temperature distribution during spark plasma sintering with COMSOL software. The results indicate that the highest power factor of 3.8 mW/m-K2 was attained in the layer structured sample, which is significantly higher than other samples due to its synergistically optimized electrical conductivity and Seebeck coefficient. Through the varied microstructure, the κ was decreased at 400 K and consequently the ZT was improved to 1.25 at 400 K for the layer structure samples. Therefore, it is suggested that layered arrangement of different microstructure material could improve the thermoelectric properties of materials. [Display omitted] • Novel fabrication of hierarchical structured material with successive arrangement of two different microstructures. • Successful consolidation of well-bonded hierarchical material and confirming by simulating results from COMSOL software. • Highest power factor of 3.8 * 10−3 W/m-K2 obtained by transportation of charge carriers through two different energy levels. • Hierarchical structured sample show highest figure of merit of 1.25 at 400 K which is highest among all reported samples. [ABSTRACT FROM AUTHOR]

We have investigated a thermally induced combustion route for preparing 2D hexagonal BN nanoplates from B 2 O 3 +(3+0.5 k )Mg+ k NH 4 Cl solid system, for k =1–4 interval. Temperature–time profiles recorded by thermocouples indicated the existence of two sequential exothermic processes in the combustion wave leading to the BN nanoplates formation. The resulting BN nanoplates were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy, PL spectrometry, and Brunauer–Emmett–Teller surface area analysis. It was found that B 2 O 3 was converted into BN completely (by XRD) at 1450–1930 °C within tens of seconds in a single-step synthesis process. The BN prepared at a k =1–4 interval comprised well-shaped nanoplates with an average edge length ranging from 50 nm to several micrometer and thickness from 5 to 100 nm. The specific surface area of BN nanoplates was 13.7 g/m 2 for k =2 and 28.4 m 2 /g for k =4. [ABSTRACT FROM AUTHOR]

Background: In South Korea, a cluster of acute lung disease patients included lung injury disease suspected of being caused by the use of humidifier disinfectants. We examined the relationship between humidifier disinfectant exposure and clinically diagnosed humidifier disinfectant-associated lung injury (HDLI) in a family-based study. Methods: This case-control study included 169 clinically confirmed HDLI cases and 303 family controls who lived with the HDLI patients. A range of information on exposure to humidifier disinfectants was obtained using a structured questionnaire and field investigations. Odds ratios (ORs) and confidence intervals (CIs) were estimated using unconditional logistic regression models that were adjusted for age, sex, presence of a factory within 1 km of residence, and the number of household chemical products used. Results: HDLI risk increased approximately two-fold or more among the highest quartile compared with the lowest quartile in terms of the hours sleeping in a room with an operating humidifier treated with disinfectant (adjusted OR = 2.0, 95 % CI = 1.1-3.7), average hours of disinfectant-treated humidifier use per day (adjusted OR = 2.1, 95 % CI = 1.0-4.5), airborne disinfectant intensity (adjusted OR = 2.6, 95% CI = 1.2-5.3), and cumulative disinfectant inhalation level (adjusted OR = 2.0, 95% CI = 1.0-4.1). HDLI risk increased as the distance of the bed from humidifier gets shorter; compared with longer distance (> 1 m), the odds ratio was 2.7 for 0.5 to 1 m (95 % CI = 1.5-5.1) and 13.2 for <0.5 m (95 % CI = 2.4-73.0). Conclusions: The use of household humidifier disinfectants was associated with HDLI risk in a dose-response manner. [ABSTRACT FROM AUTHOR]

Amorphous boron nanoparticles were synthesized by heating a B 2 O 3 + 3 Mg + k NaCl ( k is the number of moles of NaCl) exothermic mixture in a laboratory oven at 800 °C under argon flow. NaCl was used as inert material to decrease the maximum combustion temperature of the reaction mixture when it was self-ignited after the melting of Mg at 650 °C. The size of the boron nanoparticles extracted from the final product by acid leaching ranged between 30 and 300 nm for k values ranging from 1 to 5. Moreover, increasing the value of k from 1 to 5 resulted in an increase in the specific surface area of the nanoparticles from 40 to 74 m 2 g −1 . However, at k = 10, a decrease in the specific surface area to 47.56 m 2 g −1 was recorded due to incomplete reduction of B 2 O 3 . The ignition point of boron nanoparticles in air as estimated using a thermocouple was approximately 300 °C. Digital camera recording of the combustion process of boron nanoparticles in air revealed that the burning speed of the nanoparticles increased significantly from 0.3 to 15 cm/s when k increased from 1 to 5. [ABSTRACT FROM AUTHOR]

Spent nuclear fuel is electro-reduced in a chemically aggressive atmosphere wherein oxygen is generated at the anode in the presence of lithium molten salt containing a strong basic oxide, Li 2 O. Herein, the effect of the Li 2 O concentration on the hot corrosion behaviour of Haynes 263 and Inconel X-750 was investigated by immersion in molten LiCl–Li 2 O salt (1, 3, and 5 wt% Li 2 O) for 72–288 h at 650 ℃ under oxidizing atmosphere. For Li 2 O concentrations of approximately 3%, the weight loss and the products formed by the basic fluxing mechanism differed due to the dependence on the O2− concentration. • Effect of Li2O concentration on corrosion of Ni-based alloys was investigated. • Corrosion occurred by basic fluxing with O2 − ; products varied with ≥ 3 wt% Li2O. • Dense and continuous Cr-rich oxide layer prevented the inward diffusion of oxygen. • Ni-rich layer hindered outward diffusion of the alloying elements in the base metal. • Excess Fe appeared to be deleterious to the overall corrosion resistance. [ABSTRACT FROM AUTHOR]

Excessive methylmercury (MeHg) accumulation in dietary fish is a global concern due to its harmful effects on human health, however, environmental factors affecting MeHg accumulation in reservoir ecosystems are not clearly known. In this study, we aim to identify the main sources of MeHg in the water column and the critical factors related to MeHg concentration and methylation rate constant (k m) in sediment and total Hg concentration in fish using five-year (2016–2020) monitoring data of the five artificial reservoirs. The preliminary mass budgets constructed using the measurement and online data showed that sediment transport dominated over runoff in the long residence time reservoirs (400–475 days), while runoff dominated over sediment transport in the short residence time reservoirs (10 days). Whereas the sediment k m showed a comparable variation with the algal biomass, the sediment MeHg concentration and the length-normalized Hg concentration in the barbel steed and bluegill increased in the longer residence time reservoirs with lower algal biomass. As MeHg accumulation in sediment and fish tends to increase in the slowly overturning reservoirs, the hydraulic residence time should be carefully managed to meet the best protection of human health from chronic Hg exposure by fish consumption. [Display omitted] • MeHg mass budgets were estimated using the Hg data from five artificial reservoirs. • Sediment was the main source of MeHg in the long residence time reservoirs. • Runoff was the main source of MeHg in the short residence time reservoirs. • MeHg in sediment and fish were higher in the long residence time reservoirs. • Turnover period should be carefully managed to lower MeHg in reservoir fish. [ABSTRACT FROM AUTHOR]

Abstract: Herein, we present the low-temperature solid-phase combustion synthesis of tantalum carbide (TaC), TaC/tantalum silicide (TaSi2), and TaC/tantalum boride (TaB) nanoparticles by the silicothermic reduction of potassium fluorotantalate (K2TaF7) in the presence of carbon, boron, and polytetrafluoroethylene (PTFE, 1 [1] BJH, Barrett–Joyner–Halenda; HRTEM, high-resolution transmission electron microscopy; MMC, metal matrix composite; PFTE, polyfluorotetraethylene; PTFE; polytetrafluoroethylene; RF, radio frequency; SAED, selected area electron diffraction pattern; T c , combustion temperature; TEM, transmission electron microscopy; U c , combustion velocities; XRD, X-ray diffractometer. (C2F4) n ). The temperature–time profiles of the combustion wave were measured by thermocouples and used to calculate the combustion parameters: temperature and wave velocity. The flame temperature was found to increase with the concentration of PTFE. Using high resolution transmission electron microscopy, a homogeneous distribution of highly crystalline nanoparticles was observed. The thermal–kinetic activation energy, the heat released during each of the individual reactions, and the chemical mechanism of the overall combustion process are discussed with respect to the final products. [Copyright &y& Elsevier]

Tantalum nitride nanoparticles were produced from a (K2TaF7 +5NaN3) exothermic mixture under the combustion regime. The effects of the K2TaF7/NaN3 ratio and KF and NH4F concentrations on the combustion parameters, product composition, and size of the tantalum nitride particles were studied. Depending on the synthesis conditions, the combustion temperature was maintained in the 700–1200°C range, resulting in hexagonal ε-TaN, TaN0.8, and Ta2N phases. The dominant phases were TaN and TaN0.8 in the 1000–1200°C range, whereas only the Ta2N phase was present in the 700–100°C range. Pure-phase cubic tantalum nitride (δ-TaN) was produced with 4.0mol of NH4F at a combustion temperature of ~800°C. Under controlled reaction conditions, the size of the tantalum nitride particles was about 10–50nm. We also found that during the synthesis, the stainless steel tube located inside of the reaction mixture was partially coated with fine TaN crystals. The mechanism of the combustion process is discussed in regards to the experimental results. [ABSTRACT FROM AUTHOR]

Abstract: Mercury (Hg) concentrations were monitored in wild and cultured fish collected from fresh and coastal waters in the Korean peninsula from April 2006 to August 2008 nationwide. Total Hg concentrations were reported for 5043 fish samples, including 78 species from 133 locations. Significant interspecies variation was noted in the Hg levels. The average Hg concentration in each fish species ranged from 6.31μgkg−1 for mullet (Mugil cephalus) to 200μgkg−1 for mandarin fish (Siniperca scherzeri). Among the species collected, the maximum concentration of Hg, 1720μgkg−1, was measured in an Amur catfish (Silurus asotus). Only wild freshwater fish exceeded the WHO ingestion standard. Wild freshwater piscivorous fish samples from a large artificial upstream lake contained the highest Hg levels. Hg concentrations were compared between fish groups categorized as wild and farmed fish from freshwater and coastal waters. Although the wild freshwater fish had similar size ranges, their Hg concentrations were higher than those of the other groups. Compared to the feed of farmed marine and freshwater fishes, the prey of wild freshwater fish had a higher Hg concentration, and the total Hg concentrations in freshwater and associated sediment samples were higher than those in coastal water and associated sediment samples. In the freshwater environment, piscivorous fish bioaccumulated two times more Hg than carnivorous and omnivorous fish and four times more than planktivorous fish. The difference in Hg concentrations among trophic groups might have been due to differences in the size of fish, in addition to the variations among different trophic groups. These data will be useful for developing the fish consumption advisory as a management measure to reduce Hg exposure. [Copyright &y& Elsevier]

Abstract: In this paper, we describe an attractive and rapid process for preparing zirconium metal (sponge and powder) by reacting zirconium tetrachloride with magnesium powder. The process was carried out in the combustion synthesis (shortly CS) mode using a ZrCl4–2Mg exothermic mixture, which provided a temperature of 1000–1100°C and a final product consisting of MgCl2 and Zr sponge. The separation of Zr sponge from the reaction product was accomplished by dissolving MgCl2 into warm acidified water. The average size of the Zr sponge particles ranged from about 1mm to about 10mm. Micrometer-sized (from 10 to 300μm) Zr powders were also obtained after mechanical processing of sponge. The characteristics of the Zr metal were established by X-ray diffraction, scanning electron microscopy, and inductively coupled plasma spectroscopy techniques. [Copyright &y& Elsevier]

Abstract: Quasi-aligned, high-aspect-ratio AlN micro- and nanostructures were synthesized under high nitrogen pressure by the exothermic reaction of an Al+0.015mol (C2F4) n mixture. Structurally uniform AlN micro- and nanofibers with hexagonal and cylindrical morphologies were obtained when the system temperature was maintained within the range of 1600–1700°C. The fibers had aspect ratios as high as 2000, diameters in the range of ∼0.05–20μm, and were ∼100–1000μm in length. High-resolution transmission electron microscopic and selected area diffraction analyses indicated that the as-synthesized AlN micro- and nanostructures are perfectly single crystalline with preferential growth along the [001] direction. Branching was also observed in some of the micro-fibers, giving rise to randomized, two-dimensional comb textures. Based on the results obtained in the present study, a mechanism for the formation of AlN micro- and nanostructures under combustion conditions was proposed. [Copyright &y& Elsevier]

Abstract: An experimental study on the preparation of zirconium silicides was conducted using ZrSiO4–Mg, ZrSiO4–SiO2–Mg and ZrSiO4–ZrO2–Mg powder mixtures by the combustion synthesis (CS) technique. Test specimens having different composition ratios including Zr:Si=1:2, 1:1, 5:4, 5:3, 2:1, and 3:1 were employed in this study. Temperature profiles relative to all the starting compositions were measured using thermocouples, and the values of the combustion parameters (combustion temperature and wave velocity) were estimated using the same. The formation of ZrSi, ZrSi2, Zr5Si3, and Zr3Si2 phases was confirmed by X-ray analysis; however, only ZrSi was produced as a single-phase product. The proposed method was also extended to synthesize spherical ZrSi particles having mean diameters of 0.2–3.0μm. A comprehensive chemical pathway to describe the sequence of chemical reactions in the combustion wave was also proposed. [ABSTRACT FROM AUTHOR]

Abstract: Hot corrosion studies were performed on superalloy specimens. The IN713LC superalloy were sprayed with an aluminized NiCrAlY-bond coat and then with an yttria–zirconia top coat. The bare superalloy reveals an obvious weight loss due to spalling of the scales by the rapid scale growth and thermal stress. The top coatings showed a much better hot corrosion resistance in the presence of LiCl–3 wt.% Li2O molten salt when compared with those of the bare superalloy and the aluminized bond coatings. These coatings have been found to be beneficial for increasing hot corrosion resistance of structural materials for lithium molten salts. [Copyright &y& Elsevier]

Commercially available low-cost air quality sensors have low accuracy. The improved accuracy of low-cost PM2.5 sensors allows the use of low-cost sensor systems to reasonably investigate PM2.5 emissions from industrial activities or to accurately estimate individual exposure to PM2.5. In this work, we developed a new PM2.5 calibration model (HybridLSTM) by combining a deep neural network (DNN) optimized in calibration problems and a long short-term memory (LSTM) neural network optimized in time-dependent characteristics to improve the performance of conventional calibration algorithms of low-cost PM sensors. The PM2.5 concentrations, temperature and humidity by low-cost sensors and gravimetric-based PM2.5 measuring instrument were sampled for a sufficiently long time. The proposed model was compared with benchmarks (multiple linear regression model (MLR), DNN model) and low-cost sensor results. The gravimetric measurements were used as reference data to evaluate sensor accuracy. For root-mean-square error (RMSE) for PM2.5 concentrations, the proposed model reduced 41–60% of error when compared with the raw data of low-cost sensors, reduced 30–51% of error when compared with the MLR model and reduced 8–40% of error when compared with the MLR model. R2 of HybridLSTM, DNN, MLR and raw data were 93, 90, 80 and 59%, respectively. HybridLSTM showed the state-of-the-art calibration performance for a low-cost PM sensor. In other words, the proposed ML model has state-of-the-art calibration performance among the tested calibration algorithms. [ABSTRACT FROM AUTHOR]

• Consumer exposure to permethrin via the use of home insecticide spray was assessed. • Biomonitoring and mathematical modeling were conducted for 27 consumers. • The levels of metabolites increased significantly with the application of home insecticides. • The total amount of excreted metabolites was lower than estimated by the exposure model. Pyrethroids have been widely used as an active ingredient in home insecticide products since the 1960 s. Although their occurrence in indoor environments has been studied, the contribution of home insecticide application to the aggregate exposure to pyrethroids is not well known. The objective of this study was to estimate the consumer exposure to permethrin, a representative pyrethroid, via the use of home insecticide spray during the summer season using biomonitoring and personal exposure modeling. Exposure to permethrin was assessed by analyzing its urinary metabolites, 3-phenoxybenzoic acid (3-PBA) and cis / trans -3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropan carboxylic acid (cis / trans -DCCA), for a group of consumers (n = 27). The levels of metabolites were also compared with those predicted by a screening exposure model considering personal exposure parameters. The levels of metabolites in 15 participants increased significantly (p < 0.05) with the application of home insecticide products, thereby suggesting that the heavy use of home insecticides during summer could be an important exposure route of permethrin in addition to other sources, such as food consumption. The total amount of excreted 3-PBA and cis / trans -DCCA was lower than the amount estimated by the exposure model for most participants by a factor of 0.9–861.0. These differences could be attributed to the rapid loss of permethrin after application, including sorption to indoor surfaces, reaction with indoor substances, individual biological variations, and ventilation during application. However, the screening exposure model used for the initial safety assessment of biocidal products generally performed well because it did not underestimate the personal exposure to permethrin during the application of home insecticide spray. [ABSTRACT FROM AUTHOR]

The purpose of this work is to quantify the effects of dissolved zinc cations on corrosion and release rates from a pre-filmed Alloy 690 steam generator tubing material that was subsequently exposed to water containing zinc. The corrosion tests were performed in circulating 2 ppm Li and 1000 ppm B water without and with 60 ppb zinc at 330 °C. Gravimetric analyses and oxide characterization revealed that the corrosion rates, release rates, and oxide thicknesses decreased by subsequent exposure of the pre-filmed Alloy 690 to zinc. These benefits are attributed to the formation of a chromium-rich inner oxide layer incorporating zinc. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are considered to act additively when exposed as congener mixtures. Additive internal concentrations at the site of toxic action is the basis for recent efforts to establish a sum PAH guideline for sediment-associated PAH toxicity. This study determined the toxicity of several PAH congeners on a body residue basis in Diporeia spp. These values were compared to the previously established LR50 value for a PAH mixture based on the molar sum of PAH congeners and demonstrated similar LR50 values for individual PAH. These results support the contention that the PAH act at the same molar concentration whether present as individual compounds or in mixture. Aqueous exposures were conducted for 28 d, and the water was exchanged daily to maintain the exposure concentration. The concentration in the exposures declined by an average of 22% between water exchanges across all compounds, and ranged from 11% to 32%. The toxicokinetics were determined using both time-weighted-average (TWA) and time-variable water concentrations and were not statistically different between the two source functions. Toxicity was determined for both mortality and immobility (failure to swim on prodding) and on both a TWA water concentration and a body residue basis. The LC50 values ranged from 1757 μg l−1 for naphthalene after 10 d exposure to 79.1 μg l−1 for pyrene after 28 d exposure, and the EC50 ranged from 1587 μg l−1 for naphthalene after 10 d exposure to 38.2 μg l−1 for pyrene after 28 d exposure. The LR50 values for all congeners at all lengths of exposure were essentially constant and averaged 7.5±2.6 μmol g−1, while the ER50 for immobility averaged 2.6±0.6 μmol g−1. The bioconcentration factor declined with increasing exposure concentration and was driven primarily by a lower uptake rate with increasing dose, while the elimination remained essentially constant for each compound. [Copyright &y& Elsevier]

The analyses of phase composition, microstructure and the mechanical properties were conducted for as-cast Ta x Al 0.7 CoCrFeNi 2.1 (x = 0.3, 0.5, 0.6 and 0.7) eutectic high entropy composites (EHECs). With the x value increases from 0.3 to 0.6, the phases of dendrite changed from L1 2 to B2 and volume fraction of ultrafine-eutectic matrix consisting of Face-centered cubic and Laves phases increased. When x = 0.7, the Laves phase appears as the primary dendrite and the matrix region changed into the bimodal eutectic structure (L1 2 + Laves and B2 + Laves). Thermo-physical parameters could be used for understanding phase formation in EHECs. Experimental and theoretical comparison using thermo-physical parameters shows a reasonable consistency. Depending on the microstructural variation, the yield strength increased from 1304 MPa (x = 0.3) to 2154 MPa (x = 0.6) and plasticity decreased from 17% (x = 0.5) to 4% (x = 0.6). In order to understand the nano-to-micronscale deformation mechanisms depending on the microstructural variations, the systematic investigations of post-deformed samples (x = 0.5 and 0.6) were carried out by multi-scale SEM, TEM, and AFM analyses. [Display omitted] [ABSTRACT FROM AUTHOR]

Evaporation of tellurium (Te) occurs during most of the fabrication methods which leads to a strong deviation on thermoelectric properties. Due to the existence of volatile tellurium has been a great challenge to determine the accurate chemical compositions in the Bi 0.5 Sb 1.5 Te 3 compound for optimizing the carrier concentration. Herein, we systematically verify the reliability and understand the correlations between chemical composition and thermoelectric properties at different portions of large (25 mm), thick (30 mm) samples. The results reveal that spark plasma sintered samples didn't show any significant evaporation of Te. However, the chemical composition slightly changed, resulting in the final thermoelectric figure of merit at different portions of thick samples varied typically within a 10% error. Moreover, this work supports that the selection of the powder fabrication and compaction method plays a crucial role on the final thermoelectric properties of the material, as the combining of gas atomization and spark plasma sintering can prohibit the evaporation of tellurium and any possible inhomogeneous stress field or temperature distribution in large-sized graphite die to SPS. Image 1 • Determined the chemical composition at different portions of large (25 mm) and thick (30 mm) samples. • Gas atomization and subsequent spark plasma sintering process utterly prohibited the evaporation of Te. • Elucidated the relation between chemical composition and thermoelectric properties. • Verified the homogeneity effect at different positions of large-size bulk samples. [ABSTRACT FROM AUTHOR]

Decoupling the Seebeck coefficient, electrical and thermal conductivity has been a great challenge in efforts to obtain thermoelectric materials with a high figure of merit (ZT) for power generation and cooling applications. In this work, p-type Bi 0.5 Sb 1.5 Te 3 samples were fabricated by combining gas atomization and spark plasma sintering. Heat-treatment and subsequent consolidation during SPS stimulated the recrystallization of grains and reduced texture, contributing to reduced carrier scattering. This enhanced carrier mobility by 29%. The recrystallization also induces a hierarchy of fine and coarse crystal grains with random orientations. This mixed microstructure contributed to the simultaneous enhancement of the Seebeck coefficient and electrical conductivity, while reducing lattice thermal conductivity, due to effective phonon scattering by the fine grains and Sb 2 O 3 nanoparticles. The significant improvement in power factor and relatively low κ L resulted in a peak ZT of 1.1 at 350 K for the 470 °C treated sample. This was about 47% higher than the initial sample (ZT = 0.75 at 350 K). The average ZT for all the heat treated samples reached over unity in the range of 300–500 K. This work suggests that the spark plasma heat treatment and consolidation processes enable the recrystallization, allowing the thermoelectric properties to be decoupled, enhancing ZT. Image 1 • The hierarchical structures were formed in Bi 0.5 Sb 1.5 Te 3 alloys via recrystallization. • Decoupled the electrical and thermal properties by forming the hierarchical structures. • Heat-treatment and subsequent consolidation during SPS stimulated the recrystallization of grains and reduced texture. • ZT enhanced by 47% for recrystallized samples than the initial samples. [ABSTRACT FROM AUTHOR]

• The corrosion resistance of YSZ was investigated in CaCl 2 -CaF 2 -CaO molten salt. • The reactivity between YSZ and molten salt was dependent on grain size. • Chemical attack occurred preferentially at the grain boundaries over YSZ grains. • With increasing grain size, grain boundary area decreased, reducing the attack path. • Larger grain sizes resulted in reduced reaction between YSZ and the molten salt. The hot corrosion behaviour of YSZ specimens sintered at 1500 °C (6 and 11 h) and 1600 °C (11 h) was evaluated in CaCl 2 -CaF 2 -CaO molten salt at 1150 °C. YSZ sintered at 1600 °C for 11 h exhibited the lowest corrosion, whereas YSZ sintered at 1500 °C for 6 h showed the most corrosion, with a grain size dependency. XRD analysis showed that all YSZ contained mainly CaZrO 3 with a small t-ZrO 2 peak. To use SOM anodes for the electrowinning of various metals, the corrosion resistance of YSZ can be improved by adjusting the grain size instead of adding stabilizers. [ABSTRACT FROM AUTHOR]