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The development of geothermal power generation in recent years has not given cause for optimism, and the reasons behind this situation are complicated. Nevertheless, if the global geothermal power generation market is studied, some interesting phenomena are revealed. First, the development of geothermal power generation around the world is unbalanced and highly correlated with the distribution of geothermal resources; therefore, the geothermal power generation potential in each country is examined and candidate countries are selected to analyze this unbalanced global development. Further, considering that the exploitation of energy does not rest solely on resource endowment and that the market is a critical factor, the factors that may influence the market are identified by studying the history of global geothermal power generation. Although the influencing factors in each country are not the same, the analysis indicates that factors such as a country's energy strategy, energy resource location, and the sustainable development of geothermal resources play critical roles in the development of geothermal power generation. Finally, the resource endowment is jointly considered with the main factors that influence the market to create a well-organized analytical framework for other researchers. The proposed analytical framework is then applied to make a tentative preliminary judgment about the development of geothermal power generation in China. The analysis shows that China has considerable potential for geothermal power generation; however, the development prospects under the current conditions are not promising. • GPG development correlates with distribution of medium-high temperature resources. • Critical external factors influencing the development of GPG are also discussed. • Geothermal power generation in China is not promising based on current conditions. [ABSTRACT FROM AUTHOR]

• The gangue micropores are converted into mesopores and macropores. • The content of various functional groups increased and reached the maximum at S60. • Dry cracking temperature increases, other characteristic temperatures decrease. • The combustion properties all following the chemical reaction mechanism(n = 3). A large amount of coal gangue (CG) produced in coal mining accumulates to form CG hills, and the combustion properties change under the effect of leaching, increasing the risk of spontaneous combustion. The study was mainly carried out by nitrogen adsorption, infrared spectroscopy and thermogravimetry on the physicochemical properties of the CG under different immersion times (30, 60, 90 days). And the activation energy of the immersion CG at different oxidation or combustion states was calculated. The results show that the pyrite contained in gangue is oxidized after immersion, and the heat released by oxidation and the acid solution formed have an obvious effect on the pore expansion of gangue. The mesoporous and macroporous increase by 2.61% and 0.95% respectively, which strengthens the physical and chemical adsorption of oxygen for CG. The immersion process also destroys the structure of the gangue, transforming stable functional groups into active ones, especially the most significant increase in hydroxyl and oxygen-containing functional groups. The characteristic temperature changed under the action of water immersion, the cracking temperature increased, and other characteristic temperatures decreased, among which the ignition temperature decreased by about 20℃. In addition, the water immersion process inhibits the low-temperature oxidation stage of CG and promotes the high-temperature combustion stage, and the risk of spontaneous combustion is the strongest after 60 days of immersion in water. The results can provide guidance for the prevention of spontaneous combustion in drenched CG hills. [ABSTRACT FROM AUTHOR]

The crushing behavior of foamed concrete is utilized to assess the arresting properties of the Engineered Materials Arresting System (EMAS). In this study, polypropylene fibers (PPF) are used to improve the crushing behavior of foamed concrete with and without wet-dry cycles. The results indicate that the compressive strength, initial crushing stress and maximum energy absorption efficiency of foamed concrete with 0.6 % PPF is increased by 71.89 %, 60.85 % and 9.52 %, respectively. After 30 wet-dry cycles, the above three parameters are reduced to 0.21 MPa, 0.71 MPa, and 0.42, respectively, for foamed concrete without fibers, and 0.28 MPa, 0.97 MPa, and 0.44 for foamed concrete with 0.6 % PPF. The analysis based on the tire/foam interface model reveals the potential reduction of the arresting force on the landing gear caused by wet-dry cycles while the fiber reinforcement could partially offset this deterioration. Adding PPF to foamed concrete for EMAS construction has the potential to optimize cement costs and enhance arresting properties. • Crushing behavior of foamed concrete was utilized to assess the arresting properties of EMAS. • Polypropylene fibers (PPF) were used to improve the crushing behavior of foamed concrete with and without wet-dry cycles. • In the range of 0.2–1.0 % PPF fiber content, the best improvement is achieved at 0.6 % fiber content. [ABSTRACT FROM AUTHOR]

Nanoindentation and nanoscratch tests of YAG single crystals were systematically performed. The mechanical properties including elastic recovery rate, elastic modulus, nano hardness and fracture toughness of YAG single crystals were obtained by the nanoindentation tests. The surface morphologies of the scratched grooves were analysed using scanning electron microscopy. The formation characteristics of YAG single crystals induced by varied-depth nanoscratch indicated that there was distinct brittle-to-ductile transition phenomenon during the scratching process. Surface radial cracks occurred prior to the edge-breaking phenomenon, and transverse cracks extending to the surface of the work material dominated the brittle removal of YAG single crystals. A theoretical model of the edge-breaking size during the nanoscratch process was developed by considering the stress intensity factor, elastic recovery rate, and residual force. This model indicated that the edge-breaking size increased as the normal force, average elastic recovery rate and elastic modulus increased, but decreased as the nanoindenter tip radius, fracture toughness and nano hardness increased. When the average elastic recovery rate was within 17.5%–20% (the maximum elastic recovery rate was within 35%–40%), the values predicted by the theoretical model agreed well with the experimental values, and the average error was less than 5%. The model could provide theoretical guidance for analysing the surface generation characteristics of brittle solid materials during the abrasive processing at brittle removal regime. [ABSTRACT FROM AUTHOR]

When the gas explosion occurs in a coal mine, the pressure wave will induce coal dust (CD) to participate in the explosion reaction, which will further expand the accident and eventually cause more serious casualties. Based on this hazard, experiments were performed on three representative types of CD with the aid of a self-built experimental pipeline for gas/CD explosion. The explosion characteristics under the condition that pressure waves entrain different CD to participate in the explosion were studied. Furthermore, the influence of volatile content in CD on the compound explosion was analyzed from a microscopic perspective. The following beneficial conclusions were obtained: The overpressure peak value and the flame propagation velocity in the compound explosion are positively correlated with the volatile content in CD. Under those three conditions, the maximum overpressure is obtained at P2 position, and obvious stratification occurs in the process of flame propagation. However, compared with the other two working conditions, the average flame propagation speed of the composite explosion system with anthracite decreased by 51.2% and 52.6%, respectively, and flame surface breaks and becomes discontinuous earlier. After the explosion, the volatile content of three kinds of CD is significantly reduced, and the volatile content of lignite, bituminous coal and anthracite is 75.6%, 75.7% and 44.7% of the industrial analysis value of raw coal, respectively. With reference to the analysis on the microscopic test results, the amount of volatile gas decomposed from volatiles determines the intensity of the homogeneous reaction in the whole combustion process, while the coke formed after the reaction determines the intensity of the non-homogeneous reaction. Therefore, the volatile content in CD is a key factor affecting CD explosion. The research results provide an important scientific and theoretical basis for the prevention, control and reduction of CD explosion disasters. [ABSTRACT FROM AUTHOR]

Recent developments in the in-situ transformation of coal resources have heightened the possibility of exploring the oxidized coal regasification in coalfield fires. For further understanding the regasification characteristics of oxidized lignite residues in coalfield fire, Shengli lignite was selected for conducting ultra-lean oxygen pre-oxidation under different isothermal temperatures and CO 2 regasification experiments. Fourier transform infrared spectroscopy results indicate that higher temperature leads to the increase of aromatic hydrocarbon and reduction of aliphatic hydrocarbon side chains on the coal structure. It is found that the pre-oxidation of under 1% oxygen concentration and 300 °C will increase the specific surface area and pore volume, which would be beneficial for the following regasification. The analysis of gasification parameters suggests that the gasification quality and performance of lignite residues decline with the increasing oxygen concentration and rising isothermal temperatures in pre-oxidation. The kinetic analysis demonstrates that when the oxygen concentration ranges from 1% to 5%, the activation energy of gasification increases by 16.744 kJ/mol. The findings suggest that the lignite pre-oxidation under ultra-lean oxygen conditions will inevitably increase the activation energy of CO 2 gasification, which causes the coal more difficult to be utilized effectively. • The structural characteristics of lignite oxidized residues were analyzed by FT-IR. • The gasification performance of lignite residues was revealed. • The pre-oxidation with ultra-lean oxygen increases the activation energy of CO 2 regasification. • There exists dynamic compensation effect of the lignite residues in regasification. [ABSTRACT FROM AUTHOR]

[Display omitted] • Potent and selective HDAC6 inhibitors based on the Tetrahydro- β -carboline scaffold. • Computational simulations suggested the key interactions between representative 11d and HDAC6. • 11d exhibited promising neurite outgrowth-promoting activity and neuroprotective activity. Histone deacetylase 6 (HDAC6) has drawn more and more attention for its potential application in Alzheimer's disease (AD) therapy. A series of tetrahydro- β -carboline (TH β C) hydroxamic acids with aryl linker were synthesized. In enzymatic assay, all compounds exhibited nanomolar IC 50 values. The most promising compound 11d preferentially inhibited HDAC6 (IC 50 , 8.64 nM) with approximately 149-fold selectivity over HDAC1. Molecular simulation revealed that the hydroxamic acid of 11d could bind to the zinc ion by a bidentate chelating manner. In vitro, 11d induced neurite outgrowth of PC12 cells without producing toxic effects and showed obvious neuroprotective activity in a model of H 2 O 2 -induced oxidative stress. [ABSTRACT FROM AUTHOR]

• Self-sensing property of cement-based sensors under flexural load is unsatisfactory. • PVA fibers increase the electrical resistivity of cement-based sensors. • PVA fibers enhance stress–strain sensing of cement-based sensors under flexural load. Cement-based sensors have great potential for structural health monitoring, especially carbon fiber filled functional sensors. In order to improve the sensing efficiency of carbon fiber reinforced cement-based sensors under cyclic flexural loading, polyvinyl alcohol (PVA) fibers were incorporated into cement-based sensors. The PVA fibers, although increasing the electrical resistivity, significantly improved the strain and stress self-sensing properties of carbon fiber reinforced cement-based sensors under cyclic flexural loading. This study provides a new way to accurately measure the parameters of cement-based sensors under cyclic flexural loading. [ABSTRACT FROM AUTHOR]

• R 3 -CH structure especially the H atom is the most active site in coal self-heating with oxygen. • The free energy barrier of oxygen attacking R 3 -CH site is 8.28 kJ/mol. • The aromatic hydrocarbon radicals and hydroxyl radicals are significant for coal self-heating. • The carbon radical combining with an O plays a vital role in initial coal spontaneous combustion. R 3 -CH structure is a typical active group during coal self-heating. In this paper, Ph-CH(CH 3)–CH 2 -Ph was selected to analyze reaction activity as well as mechanism between R 3 -CH structure and oxygen in coal self-heating by Multiwfn and Gaussian calculation. The results demonstrate that R 3 -CH structure especially the H atom is the most active site in coal self-heating with oxygen. The oxygen attacks R 3 -CH site in the Ph-CH(CH 3)–CH 2 -Ph, which results in the breaking of C–H bond and formation of O–H bond. The free energy barrier of this oxidation reaction is 8.28 kJ/mol and the heat release of the process is 86.89 kJ/mol, which indicates that it can easily occur at room temperature. From the perspective of products, the aromatic hydrocarbon radicals and hydroxyl radicals related to the initial spontaneous combustion of coal are generated, which is of great significance for the further development of coal self-heating. Subsequently, the carbon radical is combined with a single oxygen atom to generate oxygen-containing free radical which plays vital roles in initial coal spontaneous combustion. [ABSTRACT FROM AUTHOR]

• A large-area, periodic porous Au nanoparticle (PGNP) array is fabricated. • The morphology of the PGNP can be easily tailored. • The PGNP arrays exhibit outstanding SERS activities and excellent reproducibility. • The PGNP arrays show excellent polarization independence for SERS performances. Porous noble metal nanoparticles have attracted great attention in surface enhanced Raman scattering (SERS) applications due to the presence of high-density and built-in hotspots. Herein, we develop a facile route to fabricate large-area, periodic porous Au nanoparticle (PGNP) array based on ultra-thin alumina membrane (UTAM) incorporated with annealing and dealloying techniques. The size and ligament of the PGNP can be easily tailored by changing the thickness of the deposited Au/Ag film and the dealloying time. The PGNP array exhibits excellent uniformity and high sensitivity in SERS analysis due to the periodic structure and the enormous built-in hotspots. A large Raman enhancement factor (EF) of 1.4 × 107 is achieved with a relative standard deviation (RSD) less than 6.6%. Furthermore, experimental results and numerical simulations demonstrate that this PGNP array substrate exhibit polarization independence. The facile and controllable fabrication strategy makes the substrate promising for practical applications in many SERS-based qualitative and quantitative analyses. [ABSTRACT FROM AUTHOR]

The effect of titanium-alloying on microstructure and mechanical properties of Fe35Ni35Cr20Mn10 high-entropy alloy (HEA) was studied. The microstructure was characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The mechanical properties were examined by tensile and hardness tests. After the homogenization treatment at 1000 °C for 12 h, a great amount of thick/thin η flakes are observed to form at the grain boundaries, regularly intersect-arraying with specific directions that form η-locks. It is found that both the thick and thin η-Ni 3 Ti flakes are well coherent with face-centered cubic (FCC) matrix. Ti-alloying makes the homogenized Fe35Ni35Cr20Mn10 HEA possess high yield strength (331 MPa) and excellent ductility (47.2% in elongation), exhibiting a better strength-ductility. The remarkable rise in yield strength is from fine grain strengthening, dislocation hardening and second phase strengthening that are induced by Ti alloying. The refinement of grains induced by Ti alloying, the formation of a number of clear dislocation cells in FCC matrix and many stacking faults in FCC matrix and inside η flakes during the tensile deformation, and especially the coordinated deformation between η flakes and matrix, are thought to be responsible for the excellent ductility. The excellent strength-ductility in homogenized (Fe35Ni35Cr20Mn10) 95.3 Ti 4.7 HEA is, more importantly, due to the formation of regular intersect-arraying of η flakes (η-locks) with specific directions. The thick/thin η flakes are all along keeping the coherent relationship with FCC matrix during the total tensile deformation and hence can coordinately deform with the matrix. • Thick/thin η flakes are regularly intersect-arraying that form η-locks. • The thick/thin η flakes in η-locks are well coherent with FCC matrix. • The prepared HEA exhibits an excellent strength-ductility. • The η flakes keep the coherent relationship with FCC matrix during tensile deformation. • It is found that η flakes can coordinately deform with the matrix. [ABSTRACT FROM AUTHOR]