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In this study, the evolution of microstructure and its correlation with the viscosity of CaO–SiO 2 -based melts, incorporating various Al 2 O 3 additives, have been investigated by employing in situ high temperature Raman spectroscopy and viscosity model. Raman spectra of the melts were procured at 1823 K by using in situ high temperature Raman spectroscopy. After considering the intricate influences of temperature and Raman scattering cross section (RSCS), the original Raman spectra of aluminosilicate melts underwent calibration. Subsequently, the distribution of microstructure species Q i (i = 0–4) was quantitatively performed through meticulous deconvolution of calibrated Raman spectra. The evolution of Q i species with the increasing Al 2 O 3 content reveals a decrease in Q 1 and Q 2 species, while the fully polymerized Q 4 experiences a continuous and significant growth. Concurrently, Q 3 initially exhibits an upward trend followed by a subsequent decline. The Q i evolution culminates in an overall enhancement of the degree of polymerization. Viscosity was determined by utilizing a rigorously selected viscosity model, elucidating a consistent upward trajectory as Al 2 O 3 content is incrementally added. Furthermore, a quantitative analysis of the relationship between viscosity and structure was conducted based on the average number of non-bridging oxygen per network-forming tetrahedron (NBO/T). The findings demonstrate a robust linear relationship between the logarithm of viscosity and NBO/T, thereby offering valuable insights for examining and predicting viscosity behavior of aluminosilicate systems. [ABSTRACT FROM AUTHOR]

To investigate the structural behaviors of Al3+ in aluminosilicate systems, the microstructural characteristics of CaO–SiO 2 -based glassy samples with various Al 2 O 3 contents were examined quantitatively by Raman spectroscopy and 27Al MAS NMR. A sequence of multiple model clusters of aluminosilicate systems modified with Ca2+ and Na ​+ ​cations was designed. Then quantum chemistry (QC) ab initio calculations were performed for geometric optimization, and Raman spectral simulations were carried out. The functional relationship between the Raman scattering cross section (RSCS) and stress index of silicon-oxygen tetrahedron (SIT) for aluminosilicates was established, which was successfully applied to calibrate experimental Raman spectra. Some fivefold coordinated aluminum (AlⅤ, approximately 5%) and less than 2% sixfold coordinated aluminum (AlⅥ) were detected by 27Al MAS NMR, while most aluminum remained in tetrahedral sites (AlⅣ). The ever-finer quantitative results of Raman spectroscopy and NMR showed a gradual production of AlⅣ with the addition of Al 2 O 3 , along with a significant adjustment in Q i species distribution. Specifically, Q 1 , Q 2 decreased, fully polymerized Q 4 increased and Q 3 showed a nonmonotonic variation and obtained the maximum at Al 2 O 3 ​= ​12 ​mol%. Furthermore, the effects of aluminum on bridging oxygen bond types (T-O b , T ​= ​Si, Al) and the degree of polymerization were discussed in detail. These structural features related to composition are essential theoretic foundations for understanding the properties of these systems. [ABSTRACT FROM AUTHOR]

• A mechanical equivalent model for rock-concrete composite considering interface roughness was established • A failure criterion for the compressive-shear strength of rock-concrete assemblies was derived • By combining eight types of rock with concrete, single-axis and triaxial compression tests were conducted on the composite bodies • The strength of the rock-concrete assemblies is governed by the low-strength components The combination of rock and concrete lining structures is a typical composite structure in the field of engineering. This study is based on the concept of equivalent strain energy and establishes a mechanical equivalent model for rock-concrete assemblies (RCA). Assuming that both rock and concrete satisfy the Mohr-Coulomb criterion, we derive the shear failure criterion of the equivalent model considering the roughness of the rock-concrete interface. The applicability of the model was verified through uniaxial and triaxial tests on eight different types of RCA structures. The research results indicate that an increase in confining pressure enhances the strength of the RCA. When the confining pressure reaches a certain value, concrete only experiences shear failure, and no macroscopic cracks appear in the rock. The structure of the RCA tends towards isotropy. As the height ratio of the RCA increases, its strength decreases. At minimal concrete height ratios, the strength of the RCA gradually approaches that of concrete. This study can provide valuable insights for designing and evaluating stability in engineering rock bodies within diverse geological environments. [ABSTRACT FROM AUTHOR]

In order to study the effect of MgO on the microstructure and macroscopic thermos-physical properties of calcium silicate melt, quantitative analysis of the various silicon-oxygen Q i species in magnesium-calcium silicate glasses and melts at a constant alkalinity has been performed by in-situ high temperature Raman spectroscopy, 29Si MAS NMR and DFT (Density Functional Theory) calculation. Several cluster models, probably existed in magnesium-calcium silicate glasses and melts, modified by Ca2+ or Mg2+ have been designed, their Raman vibrational modes and scattering activities were thus simulated and calculated. A function correlating the wavenumbers of Si-O nb (non-bridge oxygen) of various SiOTs (silicon-oxygen tetrahedrons) with their RSCS (Raman scattering cross sections) was constructed and used to calibrate the experimental Raman spectra. The abundance of each primary Q i species of various magnesium-calcium silicate glasses can be composed by all the deconvoluted hyperfine peaks within the same Q i species. The quantitative description for glasses was proven to be consistent with the result from 29Si MAS NMR. Thus, Q i species distributions for melts were also quantitatively derived. It demonstrated that the abundances of Q 1 and Q 3 species increased while Q 2 species decreased with the increasing replacing amount of MgO. The relationship between the viscosity and Q i species distributions as well as different cations has been investigated and correlated. Q 3 species was predominantly responsible for the contribution of viscosity of melt. [ABSTRACT FROM AUTHOR]

• A model test for failure mechanisms of deep soft rock roadways is conducted. • U shape yielding steel arches are developed. • The attenuation of radial stress leads to the initiation of cracks. • The concentration of tangential stress promotes the cracks to open. • Excavation compensation method inhibits the propagation of cracks. Traditional support (TS) is not sufficient to address the issue of large deformations in deep soft rock roadways with high stress. Based on model tests, this study considered the superposition effects of the evolution of tangential stress σ 1 and radial stress σ 3 on the crack propagation of excavated rock mass. Moreover, it explored the response characteristics and failure mechanisms of surrounding rock under different support modes. The results showed that, compared with the TS, the compensation support (CS) reduces the surrounding rock deformation, fracture and expansion area, and crack length by 73.7, 86.5, and 37.7%, respectively, while the roadway cross-sectional area increases by 36.8%. At 0.5R, σ 3 of the shallow surrounding rock increases by 68.3%, and the peak value of σ 1 at this location drops by 18.2%. The excavation effect causes σ 3 and σ 1 of the surrounding rock to decrease and increase, respectively. The decrease in σ 3 leads to initiation of microcracks in the shallow surrounding rock, whereas the increase in σ 1 causes the cracks to further open and propagate deeper. Finally, the dislocation, slippage and overturning of the fractured rock blocks along the structural planes result in bulking deformation of the shallow surrounding rock. The occurrence of microcracks in the deep surrounding rock leads to dilatation deformation. The CS strongly compensates for the stress of surrounding rock through negative Poisson's ratio (NPR) cables, giving full play to the triaxial strength of the surrounding rock and mobilising the self-bearing capacity of the deep rock mass, thereby inhibiting the propagation and penetration of cracks. In contrast, the TS cables have a low prestress and weak excavation compensation effect, which makes it difficult to inhibit the evolution and coalescence of cracks, leading to large deformations in the surrounding rock. [ABSTRACT FROM AUTHOR]

It's well known that the lamellar (LAM) and five-fold-twinning (FFT) structures are two primary patterns during the early crystallization stage of FCC (face-centered cubic) metals. In this letter, we add a new third one, i.e. a nested tetrahedral lamellar (NTL) structure. In common with LAM and FFT, NTL is also a mixture of FCC and HCP (hexagonal close-packed). Differently, NTL has four tetrahedral growth orientations corresponding to four cellular bulges and a central core of tetrahedral shells nested one-by-one. This NTL acts also as the precursor of FFT and it has great differences in growth morphology and kinetics with LAM. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Abstract: The Raman spectra of aluminum nitride were measured over the temperature range from room temperature to 1273 K. Frequencies of the E21, A1(TO), E22, E1(TO), A1(LO) and E1(LO) phonon modes are 252, 614, 658, 672, 894 and 912 cm−1, respectively. The Raman peaks of A1(TO) and E22 modes are shifted toward lower frequency with temperature, which indicate that the compressive stress in the compact of aluminum nitride relax gradually when temperature is increased. The width of the Raman peaks of the A1(TO) and E22 modes are also broadened with increasing temperature. The powders of aluminum nitride readily react with water vapor in the air to product Al(OH)3 or AlOOH. These reaction products will decompose at elevated temperatures; this will affect the measurement of the Raman spectra. [Copyright &y& Elsevier]

The present study has proposed a promising liquid-liquid extraction system using novel extractants of 15-crown-5 (15C5), benzo-15-crown-5 (B15C5), and thia-benzo-15-crown-5 (TB15C5) for selective indium recovery from end-of-life liquid crystal displays (LCDs) leaching solution. The focus was placed on the selectivity of the crown ethers toward In3+ over the most competing ion of Sn2+. The molecular design of the crown ethers and their complexations with In3+ were theoretically evaluated through density functional theory (DFT) modeling from the perspectives of geometrical structure, electrostatic potential, independent gradient model, molecular orbital and thermodynamic analysis. The results show that the complexation affinity of the crown ethers toward In3+ is in the order of 15C5 > B15C5 > TB15C5. On the basis of the theoretical analysis, the target crown ethers of 15C5, B15C5, and TB15C5 were synthesized and the corresponding solvent extraction experiments were carried out. The experimental results are in excellent agreement with the theoretical evaluations that 15C5 has the best selectivity to In3+ over Sn2+ among the three crown ethers with the separation coefficient being 5.5, which is followed by 4.1 for B15C5 and 1.6 for TB15C5. [Display omitted] • Novel indium-selective extractants of 15C5 and its derivatives were synthesized. • The complexes of In3+ with 15C5 and its derivatives were theoretically evaluated. • Solvent extraction experiments were conducted for indium and tin separation. • The complexation mechanisms of In3+ with 15C5 and its derivatives were clarified. • An efficient In3+ extraction system was developed based on supramolecular chemistry. [ABSTRACT FROM AUTHOR]

In the present study, a novel process for effective recoveries of Te and Cu from copper telluride from anode slime processing in copper smelters was proposed. The process consists of two hydrometallurgical steps of atmospheric alkaline leaching for Cu and Te separation, and TeO 2 precipitation with H 2 SO 4 for Te recovery. The effects of NaOH concentration, liquid to solid ratio, temperature, H 2 O 2 to Cu 2 Te mole ratio, and reaction time on the dissolution behavior of tellurium were investigated. A Te leaching efficiency of about 91% was obtained under the optimal experimental conditions. The results of thermodynamic and kinetic analysis indicate that a lower temperature is favorable for the dissolution of Te, and mass transfer inside the solid particle is the rate-determining step. In addition, a mechanochemical-assisted leaching was conducted, by which Te leaching efficiency was enhanced to approximately 93% with ball milling at 180 rpm for 5 h. After Te leaching, H 2 SO 4 was utilized to adjust the pH value of the Te-containing alkaline leach solution to 4.5 for TeO 2 precipitation. The crystallization of TeO 2 can be completed by reacting for 1 h and the overall tellurium recovery has reached nearly 90%. Image 1 • One-step separation of Cu and Te was achieved by atmospheric alkaline leaching. • Thermodynamic and kinetic analysis of Te dissolution process were conducted. • Ball milling treatment was employed to enhance Te selective dissolution process. • An overall Te recovery of 90% was achieved by precipitating TeO 2 from solution. • A complete and efficient technology for copper telluride recycling was proposed. [ABSTRACT FROM AUTHOR]

Copper telluride is a sort of solid waste generated from copper anode slime processing, from which the recovery of copper and particularly the high-value element of tellurium always encounter technical difficulties due to the complex physicochemical properties of tellurium. In this study, an efficient and compact process for copper telluride recycling has been developed. Efficient separation of tellurium and copper from copper telluride was achieved through a pressure oxidizing alkaline leaching process under the optimal conditions of 5 mol/L for NaOH concentration, 5:1 for liquid to solid ratio, 150 °C for temperature, 0.7 Mpa for system pressure, and 2 h for reaction time, by which over 95% of tellurium was selectively dissolved in the solution and copper was enriched in the solid phase mainly in the form of copper oxides. Tellurium was subsequently recovered as TeO 2 by neutralization of the alkaline leaching solution with sulfuric acid to pH 4.5, delivering a TeO 2 precipitation efficiency of over 95%. In general, the masses of tellurium and copper balanced well in both the liquid and solid phases for each step, and the overall recovery efficiencies of Te and Cu reached as high as approximately 91% and 98%, respectively. Unlabelled Image • Atmospheric and pressure oxidizing alkaline leaching processes were compared. • One-step separation of Cu and Te was achieved by pressure alkaline leaching. • Thermodynamic and kinetic analysis of Te dissolution process were conducted. • Overall recovery efficiency of 91% and 98% for Te and Cu respectively were reached. • A complete and efficient technology for copper telluride recycling was proposed. [ABSTRACT FROM AUTHOR]