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In this study, granite wastes based glass-ceramics containing Eu 2 O 3 as simulated radionuclides is successfully synthesized via solid-state sintering method. The structure, mechanical properties and chemical durability are deeply investigated. The main phase in this glass-ceramics is oxyapatite (Ca 2 Eu 8 (SiO 4) 6 O 2), which is dispersed homogenously in glass matrix. The density dominates the properties of Vickers hardness and bending strength. The glass-ceramics containing 40 wt % of Eu 2 O 3 has the optimal mechanical properties, with the Vickers hardness, bending strength and density of 5.12 GPa, 79.44 MPa and 98.77 %, respectively. The 28 days leaching experiments show that the glass-ceramics containing 40 wt % of Eu 2 O 3 possess excellent chemical durability. The leaching rate of Al3+, Si4+, Fe3+, Ca2+, Eu3+ are 2.3 × 10−4 g m−2 d−1, 6.0 × 10−4 g m−2 d−1, 1.2 × 10−7 g m−2 d−1, 1.4 × 10−4 g m−2 d−1, 3.6 × 10−8 g m−2 d−1, respectively. This study indicates that granite wastes based glass-ceramics have excellent chemical stability and mechanical properties, which provides a novel idea for the immobilization of radioactive wastes. [ABSTRACT FROM AUTHOR]

In this study, a secondary sintering process was adopted to optimize the preparation process of single-phase high entropy A 2 Zr 2 O 7 pyrochlore-based waste forms by spark plasma sintering (SPS). This method eliminates the significant internal stress when preparing samples directly by SPS, and thus well preserves the integrity of the samples after annealing. The phase composition, microstructure, and leaching properties of high entropy A 2 Zr 2 O 7 pyrochlore were systematically investigated. Owning to the low sintering temperature (1450 °C) and short held time (3 min), the high entropy A 2 Zr 2 O 7 pyrochlore exhibited a fine average grain size of 0.8 μm. The high entropy A 2 Zr 2 O 7 pyrochlore oxides exhibit a reliable leaching resistance with low normalized release rates around 10−5 g/(m2∙d) for all elements. For the high entropy systems, the aqueous durability is mainly determined by the average grain size of ceramics and the temperature of the leaching test as well as traditional pyrochlore ceramics solidification. [ABSTRACT FROM AUTHOR]

In this work, an efficient method for the synthesis of high-entropy pyrochlore ceramic (La 1/7 Nd 1/7 Sm 1/7 Eu 1/7 Gd 1/7 Dy 1/7 Ho 1/7) 2 Zr 2 O 7 (7RE 2 Zr 2 O 7) was developed via reactive spark plasma sintering. The sintering reactivity, phase composition, microstructure, and mechanical properties of 7RE 2 Zr 2 O 7 were systematically investigated. With the aid of uniaxial pressure and direct current (DC) pulse voltage, the entire sintering process was greatly shortened to less than 1 h. Owing to the synergistic effects of the compositional complexity and severe lattice distortion, 7RE 2 Zr 2 O 7 exhibited a reduced average grain size of only 1.45 μm, which is approximately 1/6 of that for Gd 2 Zr 2 O 7 prepared using the same sintering process. Furthermore, 7RE 2 Zr 2 O 7 possessed a high hardness of up to 13.86 GPa, while a low fracture toughness of 1.1 MPa m1/2, which can be mainly attributed to the severe internal stress and defects originated from the fast-sintering process. This work is expected to provide a guidance for the highly efficient and rapid preparation of high-entropy A 2 B 2 O 7 oxides, especially for those compositions that are difficult to densify. [ABSTRACT FROM AUTHOR]

Spark plasma sintering (SPS) is a fast and efficient method for preparing functional ceramics. This article investigates the phase evolution, thermal expansion and chemical stability of traditional (Y 1.2 Nd 1.8 Fe 5 O 12) and high-entropy ((Y, Gd, Sm, Eu, Dy) 3 Fe 5 O 12) garnet ceramics. Prepared under conventional SPS (50 MPa) conditions at 900–1100 °C. The results indicate that using SPS sintering method can significantly reduce the sintering temperature (1100 °C) and time (3 min) of garnet ceramics. (Y, Gd, Sm, Eu, Dy) 3 Fe 5 O 12 (1.6 × 10−6 K−1) exhibits superior thermal expansion stability compared to Y 1.2 Nd 1.8 Fe 5 O 12 (5.4 × 10−6 K−1). The strong REE-O bond energy and severe lattice distortion of high entropy garnet ceramics hinder the migration and diffusion of cations, resulting in higher leaching resistance of high-entropy garnet ceramics (∼10−7 g m−2 d−1-10−8 g m−2 d−1) compared to traditional garnet ceramics (∼10−5 g m−2 d−1-10−6 g m−2 d−1). Therefore, SPS has broad application prospects in the low-temperature preparation of high-entropy garnet ceramics for immobilization of actinide elements. [ABSTRACT FROM AUTHOR]

When exposed to severe environments, the short-range order in pyrochlores significantly influences their physicochemical properties. Using the DFT + U method, this study investigates the effect of short-range order on the solubility of actinides (An = Th, U, Np, Pu, Am, and Cm) in Gd 2 Zr 2 O 7 with distinct coordinated Gd and Zr sites. Our findings indicate that all the actinides under consideration are susceptible to being incorporated into the 7-fold Zr-site of quasi -weberite Gd 2 Zr 2 O 7. The weberite-like short-range order also favors immobilization of these actinides in the 6-fold Zr-site. The effect of the weberite-like motif on the solubility of actinides in the Gd-site of quasi -WB Gd 2 Zr 2 O 7 depends on the chemistry of the actinides. Furthermore, the short-range order results in a lower solution energy for An incorporation into the Gd and Zr sites of the quasi -weberite Gd 2 Zr 2 O 7 with cation antisites, thereby favoring An immobilization in a disordered environment. These results strongly demonstrate the importance of the short-range order on the solubility of actinides in disordered pyrochlores. [ABSTRACT FROM AUTHOR]

Equiatomic multicomponent transition metal carbides containing different metal element numbers and carbide components were prepared from monocarbides by spark plasma sintering. The compositional effect on their mechanical properties were investigated in detail. Results indicate that all solid solutions exhibit higher hardness, strength, and modulus values than those obtained from rule of mixture, and it is prone to obtain higher mechanical properties in high-entropy compositions. Nevertheless, the variations of hardness, strength, toughness, and modulus show diverse trends upon the change of composition in carbide solid solutions. By comparison and analysis, it was concluded that entropy-related solid solution effect is a crucial parameter influencing the mechanical properties of metal carbides, however, other parameters such as microstructure, type of base monocarbides, phase purity are also negligible parameters which can have big influence on the overall mechanical properties. [ABSTRACT FROM AUTHOR]

In this study, 37 kinds of high-entropy pyrochlore/fluorite ceramics with equiatomic multicomponent compositions were successfully synthesized and the process of phase transformation was also investigated. Eventually, the experimental results show that 33 among the high-entropy compounds exhibit a single pyrochlore/fluorite structure with all cations randomly and uniformly distributed at A and B sites. Meanwhile, the ionic radii, valence, and size disorder may be the main driving forces for the formation of single-phase high-entropy pyrochlore/fluorite oxides. Furtherly, the average radius ratio(r A /r B) is the main factor of the pyrochlore/fluorite phase transformation. And when the average radius ratio(r A /r B) extends from 1.46 to 1.78, the high-entropy pyrochlore structure is stable. When the average radius ratio r A /r B is less than 1.46, it transforms into the defective fluorite structure. This study not only further expands the high-entropy pyrochlore family and but also is expected to guide the design of high-entropy pyrochlore through composition customization. [ABSTRACT FROM AUTHOR]

• Mesua ferrea flower is a rich source of polycyclic polyprenylated acylphloroglucinols (PPAPS). • PPAPs are responsible for the antibacterial activity of Mesua ferrea. • The ester substitution at C-29 in PPAPs increased their antibacterial activity. Five new polycyclic polyprenylated acylphloroglucinols (PPAPs), named mesuaferroic acids H, I, J, K and L (1 – 5), together with mesuaferroic acid C (6) and laxifloranone (7), were isolated from the petroleum ether extract of Mesua ferrea flower. Their structures were elucidated by comprehensive spectroscopic techniques including 1D, 2D NMR and HRESIMS. Compounds 1 and 7 exhibited excellent antibacterial activity against Staphylococcus aureus ATCC25923 and a series of multi-drug resistant Gram-positive clinic isolates and the MIC values ranged from 1.0 –16.0 μg/mL, which indicated that the PPAPs might be a new leading structure in antibiotic research. [ABSTRACT FROM AUTHOR]

Multicomponent oxides with pyrochlore structure (A 2 Zr 2 O 6 O') containing up to 7 different cations with equiatomic amounts have been successfully synthesized, which broadens pyrochlore solid solutions to high entropy pyrochlore oxides. XRD and Raman results indicate that all compositions possessed single-phase pyrochlore structure and the HAADF-STEM images with corresponding EDS mapping demonstrate that all cations were randomly and homogeneously distributed. This new class of high-entropy pyrochlore oxides may open a new research direction in pyrochlore-based materials. [ABSTRACT FROM AUTHOR]

Hotels in some countries or regions can not currently establish the energy benchmarking model based on statistical analysis due to the lack of building data. In this case, it is a question how to define an energy benchmarking model with fairness and comparability. To alleviate this problem, this paper, taking the budget (limited service) hotel as an example, develops an energy benchmarking model with composite indicator. At first an energy efficiency indicator is defined as EEUI (Equivalent Energy Use Intensity), which is indicated by energy consumption of unit hotel characteristics. The hotel characteristics involve both the business characteristics and energy use characteristics. The proposed energy benchmarking model is expressed by the weighted sum of major factors impacting on energy use, where EEUI is regarded as the dependent variable while the major factors are regarded as the independent variables. The coefficients of the independent variables are determined by the optimization model built in this paper. In the optimization model, the benchmark value of EUI (energy use intensity) provided by the nation or hotel industry is used as the benchmarking target. Finally the proposed energy benchmarking model is tested on the budget hotels. The purpose of this paper is to provide a simple energy benchmarking model with fairness and comparability to support the macro planning and management of energy saving and emission reduction urgently required by the hotel industry. [ABSTRACT FROM AUTHOR]

Carbide solid solutions show diverse oxidation behaviors at 1000–1400 °C in water vapor. (Ti,Nb,Ta,Hf,Zr)C and (Ti,Nb,Ta,Hf)C exhibit parabolic or near-parabolic oxidation kinetics, while the oxidations of (Ti,Nb,Ta) and (Ti,Nb)C are mainly controlled by linear oxidation kinetics. The oxidation kinetics of (Ti,Nb,Ta,Hf,Zr)C shows a tendency of transition from parabolic to linear oxidation rate law with increasing temperature. On the contrary, a tendency of transition from linear to parabolic rate law with increasing temperature was observed in (Ti,Nb)C, which exhibits the highest oxidation resistance at investigated temperatures. The presence of dense Nb-doped TiO 2 oxidation layer is responsible for the high oxidation resistance. • Compositional influence on oxidation behaviors of metal carbide solid solutions in 1000–1400 °C water vapor was investigated. • Diverse oxidation behaviors were observed for different carbide solutions. • Binary (Ti,Nb)C shows optimized oxidation resistance among all carbides solid solutions investigated. [ABSTRACT FROM AUTHOR]

The properties of rare-earth (RE) monosilicates can be regulated by solid solution engineering based on the mixture rule. The combination and number of RE principals are critical factors for better performances. In the present study, four single-phase equimolar multicomponent RE-monosilicate solid solutions including (Dy 1/3 Er 1/3 Yb 1/3) 2 SiO 5 , (Ho 1/3 Er 1/3 Yb 1/3) 2 SiO 5 , (Y 1/4 Er 1/4 Tm 1/4 Lu 1/4) 2 SiO 5 and (Dy 1/4 Er 1/4 Tm 1/4 Yb 1/4) 2 SiO 5 were synthesized by solid-state reaction and hot-pressing method. The microstructures, thermal and mechanical properties, and corrosion resistance to high-temperature water vapor were systematically investigated. Compared to the single-principal and ternary RE-monosilicates, the quaternary RE-monosilicates exhibited lower thermal conductivity of 1.32 Wm−1K−1 at 400 °C, matched thermal expansion coefficients (3.3 × 10−6/oC ∼ 5.8 × 10−6/oC from 200 °C to 1000 °C) with SiC, and much lower weight loss during water vapor corrosion. The results indicate that the increase of the RE element number can promote the grain growth, lower the thermal conductivity and thermal expansion coefficient, and enhance corrosion resistance. [ABSTRACT FROM AUTHOR]

A novel strategy of fabricating compositionally complex MAX phases was successfully developed. Multicomponent 413 MAX phase solid solutions (Ti 0.36 Nb 0.27 Ta 0.37) 4 AlC 2.8 and (Ti 0.28 Nb 0.26 Ta 0.28 V 0.18) 4 AlC 2.9 simultaneously containing 3 and 4 transition-metal elements at M site were experimentally synthesized via hot pressing equimolar mixture of 211 type MAX phase powders. By elemental analysis and structural characterization, it can be verified that those uniform compositionally complex solid solutions can be obtained only in the presence of Cr 2 AlC in raw powders. Those compositionally complex MAX phase solid solutions exhibit typical layered structures with distinct elongated grains. This discovery further enriches the MAX phases family and provide a new avenue for tailoring the properties of these materials. MAX phase composites containing around 87.5 vol.% (Ti 0.36 Nb 0.27 Ta 0.37) 4 AlC 2.8 exhibit a high flexural strength of 720 MPa and a high fracture toughness of 9.5 MPa m0.5. [ABSTRACT FROM AUTHOR]

Macroscopic parallel aligned non-woven carbon fibers were incorporated into Al 2 O 3 composites in this study to evaluate the contribution of multiple reflections to the total electric magnetic interference (EMI) shielding. Results indicate that parallel aligned non-woven carbon fiber layers contribute significantly to the total EMI shielding effectiveness (SE T) of Al 2 O 3 composites by largely enhancing the EMI absorption, and seven parallel aligned thin non-woven carbon fiber layers finally make the almost microwave-transparent Al 2 O 3 an excellent EMI shielding material with an EMI SE T as high as 29–32 dB in the X-band frequency range. The volume fraction of carbon fibers in Al 2 O 3 composites with seven carbon fiber layers is calculated to be only 0.5%, and therefore the EMI SE enhancement efficiency by parallel aligned large non-woven carbon fiber layers is much higher than other highly conducting nano fillers. It validates the significance of multiple reflections in achieving high EMI shielding properties in ceramic composites and provides an instructive approach to design efficient EMI shielding ceramic composites. [ABSTRACT FROM AUTHOR]

In order to achieve government's supervision on enterprise's carbon emissions, it should be considered how to introduce carbon tax of carbon tax system into product design and how to handle resulting chain reaction and impact. Thus, it needs to handle not only the coupling or conflict among the design objectives of performance, cost, and carbon tax of enterprise product, but also the coupling or conflict of requirements among enterprise, user, and government. For handling this problem, this paper develops a low-carbon product multi-objective optimization design method for meeting triple win requirements of enterprise, user, and government, which is called L-CPMOD for short. This method successively builds trilateral requirement model, enterprise, user, and government their own requirement submodel, a three-level coupled systematic multi-objective optimization problem that is very difficult to solve. Thus, this paper proposes a solving approach that uses Non-dominated Sorting Genetic Algorithm II (NSGA-II) with a simplified solving strategy (NSGA with strategy way for short), which employs system decomposition, coupling relationship among variables and transformations among models in every layer. Finally, a case study shows that the proposed method is feasible. [ABSTRACT FROM AUTHOR]

Multi-components and equimolar rare earth monosilicates, (Y 1/3 Dy 1/3 Er 1/3) 2 SiO 5 , (Y 1/3 Dy 1/3 Lu 1/3) 2 SiO 5 , (Y 1/4 Dy 1/4 Ho 1/4 Er 1/4) 2 SiO 5 and (Yb 1/4 Dy 1/4 Ho 1/4 Er 1/4) 2 SiO 5 , were prepared by solid-state reactions and the following hot-pressing. Dense microstructures with uniform elemental distributions were obtained for all samples. These investigated multi-components monosilicates exhibit low thermal conductivities and similar coefficients of thermal expansion with SiC. Moreover, they exhibit high corrosion resistances in 1400 °C water vapor, especially, four-components (Y 1/4 Dy 1/4 Ho 1/4 Er 1/4) 2 SiO 5 and (Yb 1/4 Dy 1/4 Ho 1/4 Er 1/4) 2 SiO 5 experienced almost invariable weights after small weight losses during the initial 0.5 h. All those results indicate that multi-components rare earth monosilicates are promising candidates of environmental barrier coatings for SiC/SiC composites. [ABSTRACT FROM AUTHOR]

(Ti 0.8 Nb 0.2)C exhibits high oxidation resistance in water vapor up to 1300 ºC, with the addition of 10% wt. SiC, even higher oxidation resistance could maintain up to 1500 ºC. The oxidation scales of both (Ti 0.8 Nb 0.2)C and (Ti 0.8 Nb 0.2)C-SiC composite show preferential oxidation and steep, opposite chemical gradients of Ti and Nb, implying that the predominant controlling factor is the outward diffusion of the metal elements by the interstitialcy mechanism. Dense and oriented (Ti 1−x Nb x)O 2 oxidation scale accounts for the high oxidation resistance. A continuous and dense SiO 2 layer further improved the oxidation resistance in (Ti 0.8 Nb 0.2)C-SiC composite. • (Ti 0.8 Nb 0.2)C and (Ti 0.8 Nb 0.2)C-SiC with high oxidation resistance in water vapor up to 1500 °C were reported. • The outward diffusion of metal elements through interstitialcy mechanism plays a dominating role. • (Ti 1−x Nb x)O 2 oxidation scale and the contentious SiO 2 layer are responsible for the high oxidation resistance. [ABSTRACT FROM AUTHOR]