The development of non-noble metal electrocatalysts for the Oxygen Evolution Reaction(OER)is advancing towards the use of multi-element *** reveal the complex correlations of multielement OER electrocatalysts,we devel...
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The development of non-noble metal electrocatalysts for the Oxygen Evolution Reaction(OER)is advancing towards the use of multi-element *** reveal the complex correlations of multielement OER electrocatalysts,we developed an iterative workflow combining high-throughput experiments and AI-generated content(AIGC)*** increased number of 909(compared to 145 in previous literature)universal descriptors for inorganic materialsscience were constructed and used as Artificial Neural Network(ANN)input.A large number of statistical ensembles with each ANN individual ensemble having a reduced number of descriptors were integrated with a new Hierarchical Neural Network(HNN)*** algorithm addresses the longstanding challenge of balancing overwhelming descriptor numbers with insufficient datasets in traditional ANN approaches to materialsscience *** a result,the combination of AIGC and experimental validation significantly enhanced prediction accuracy,increase the R2 values from 0.7 to 0.98 for Tafel slopes.
The nature of the surface basicity of two series of highly pure, chemically and/or thermally pretreated carbons has been investigated by (a) HCl adsorption, (b) stepped temperature-programmed desorption, (c) electroph...
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The nature of the surface basicity of two series of highly pure, chemically and/or thermally pretreated carbons has been investigated by (a) HCl adsorption, (b) stepped temperature-programmed desorption, (c) electrophoresis, and (d) mass titration. Following a comprehensive review of the pertinent literature, it is concluded that two mechanisms are necessary and sufficient to account for the basic properties of carbons. For carbons having low oxygen contents, molar HCl/O adsorption ratios exceeding two indicate that an oxygen-free type of site is involved in the adsorption process. Evidence favoring electron donor-acceptor (EDA) interactions of the type C(pi) + H3O+ double-line arrow pointing left and right C(pi)-H3O+ is presented. The postulated C(pi) site and its interaction with adsorbed H3O+ ions is described in detail. As the oxygen content of the carbon increases, the molar HCl/O ratios decrease sharply and level off at nonzero values, which are small due to the presence of nonbasic surface oxides. When these are removed by heat treatment (at 1073 K), the molar HCl/O adsorption ratio is again found to exceed two at low oxygen coverages, but levels off at ca. 1 for higher oxygen coverages. Of all the basic surface oxides proposed in the literature, only the pyrone-type groups can account for this HCl/O ratio. Therefore, it is proposed that the basicity of carbon surfaces arises from a combination of EDA and pyrone-type interactions. The predominance of either will be dictated by the oxygen content of the carbon in question.
Conventional flash pyrolysis-gas chromatography-mass spectrometry has traditionally been used for the characterization of complex geological substances such as humic materials, but the technique appears to provide a b...
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Conventional flash pyrolysis-gas chromatography-mass spectrometry has traditionally been used for the characterization of complex geological substances such as humic materials, but the technique appears to provide a biased representation of the structural components of very polar materials such as humic substances, probably because the polar compounds have insufficient volatility to be analyzed efficiently by gas chromatography. A new technique of in situ methylation (ISM) with tetramethyl ammonium hydroxide, introduced for oxygenated polymers, is applied to humic substances and shown to yield methylated products believed to be more characteristic of the structural components of these polar macromolecules from soils than are data from conventional pyrolysis without methylation. The discovery of benzenecarboxylic acids and long-chain aliphatic acids as the predominant constituents of three humic acids in ISM pyrolysis indicates that a reevaluation of recent structural models of humic acids which are based on conventional pyrolysis studies is in order.
The gasification reactivity profiles of different carbons (chars) are analyzed from both a theoretical and an experimental point of view. The virtues of and/or problems with utilizing the concepts of total surface are...
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The gasification reactivity profiles of different carbons (chars) are analyzed from both a theoretical and an experimental point of view. The virtues of and/or problems with utilizing the concepts of total surface area (TSA), active surface area (ASA), and reactive surface area (RSA) to explain or predict gasification rate variations with conversion are discussed. An analysis of several models of char gasification kinetics which predict the evolution of TSA with conversion revealed that the experimentally observed reactivity variations with conversion in carbon dioxide may be explained using just the initial properties of the char. An experimental investigation of char gasification in carbon dioxide using the transient kinetics approach gave a direct measurement of RSA. Gasification rates normalized with respect to RSA were essentially constant over the entire conversion range. A temperature-programmed desorption technique was also used to determine the amount of reactive surface intermediate formed on these chars during gasification in carbon dioxide; the results were in agreement with those obtained from transient kinetics. The application of these two independent but complementary techniques provided the heretofore elusive quantitative experimental explanation of reactivity variations with conversion for char gasification in carbon dioxide.
An investigation of the influence of crystalline morphology on fatigue crack propagation (FCP) resistance in a slightly branched polyethylene is presented. Various thermal histories have been utilized to generate samp...
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An investigation of the influence of crystalline morphology on fatigue crack propagation (FCP) resistance in a slightly branched polyethylene is presented. Various thermal histories have been utilized to generate samples with different crystalline microstructures and the samples were characterized thoroughly using standard methods. Estimation of tie molecule densities was obtained from measurements of brittle fracture stress. Differences in FCP behaviour for the quenched and annealed samples were shown to be dictated by a competing effect between the degree of crystallinity and tie molecule density. Further, larger spherulite size and distribution appeared to have a deleterious effect on fatigue properties. In general, crystalline microstructure is shown to have a significant influence on fatigue crack propagation behaviour.
A shear transformation has previously been shown to account for the discontinuities or jumps in the crystallographic thermal expansion coefficients across the normal to superconducting transition temperature. The crys...
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A shear transformation has previously been shown to account for the discontinuities or jumps in the crystallographic thermal expansion coefficients across the normal to superconducting transition temperature. The crystallographic stress dependence of the superconducting transition temperature is shown here to also support a shear transformation;dT(c)/dtau = 4 K/GPa. The shear motion of the lattice restricts the elastic compliances involved in superconductivity to tetragonal symmetry while considering all nine elastic interactions with the orthorhombic super-conducting crystal. The shear transformation has isothermal elastic interactions with the lattice through the orthorhombic shear compliance changes of (DELTAs11 + DELTAs22 - 2DELTAs12). The onset of superconductivity restricts to a higher symmetry the shear motion of the orthorhombic lattice with DELTAs11 = DELTAs22 and DELTAs23 = DELTAs13 across the superconducting phase boundary. Crystallographic second order thermodynamics predicts that isothermally DELTAs11 = -DELTAs12 = 1.7 X 10(-15)/Pa. It is shown that the jumps in the elastic compliance matrix are unique functions of the thermal expansion matrix jumps and the heat capacity jumps for any second order phase transition.
The mechanical properties, chemical properties and biocompatibility of Mg-3Sn-0.5Mn alloy were tested. A series of in vitro evaluations such as tensile test, static and dynamic immersion test, hemocompatibility test a...
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The mechanical properties, chemical properties and biocompatibility of Mg-3Sn-0.5Mn alloy were tested. A series of in vitro evaluations such as tensile test, static and dynamic immersion test, hemocompatibility test as well as cytotoxicity test were presented, with commercial magnesium alloy WE43 as the control. Mg-3Sn-0.5Mn alloy possesses suitable strength and superior ductility compared with WE43 and AZ31. Static immersion and dynamic degradation tests showed more uniform degradation with a more moderate rate for Mg-3Sn-0.5Mn alloy （0.34 mm/y in static condition and 0.25 mm/y in dynamic condition） compared with WE43 alloy （0.42 mm/y in static condition and 0.33 mm/y in dynamic condition） in Hank＇s solution. Blood compatibility evaluation suggested that Mg-3Sn-0.5Mn alloy had no destructive effect on erythrocyte and showed excellent anti-thrombogenicity to blood system. Besides, Mg-3Sn-0.5Mn alloy showed no inhibition effect to L929 metabolic activity and mild toxicity to vascular smooth muscle cell （VSMC） in preliminary cell viability assessment. By considering its excellent mechanical strength, corrosion resistance, low ion release rate and good biocompatibility, Mg-3Sn-0.5Mn alloy may be a promising economical candidate as biomedical implant material for load-bearing clinical applications in the future.
The electrochemical behavior of iron has been characterized in aqueous ammoniacal ammonium carbonate solution. Pure iron anodically polarized in He‐ or solutions exhibits both stable active (, SHE) and passive region...
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The electrochemical behavior of iron has been characterized in aqueous ammoniacal ammonium carbonate solution. Pure iron anodically polarized in He‐ or solutions exhibits both stable active (, SHE) and passive regions. A cathodic loop was observed in the potential range of −380 to 100 mV. It is suggested, on the basis of cathodic polarization curves of a graphite electrode in various concentrations of ammoniacal solution, that the cathodic loop is due to oxygen discharge. The addition of to the ammoniacal solution has the same effect as oxygen in that it increases the cathodic current and potential range of the cathodic loop and, as such, functions as a strong oxidant.
Stability level of tunnels that exist in an underground mine has a great influence on the safety,production and economic performance of *** of stability for soft-rock tunnels is an important task for deep coal mines l...
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Stability level of tunnels that exist in an underground mine has a great influence on the safety,production and economic performance of *** of stability for soft-rock tunnels is an important task for deep coal mines located in high in situ stress *** the available information on stratigraphy,geological structures,in situ stress measurements and geo-mechanical properties of intact rock and discontinuity interfaces,a three-dimensional numerical model was built by using 3DEC software to simulate the stress conditions around a tunnel located under high in situ stress conditions in a coal rock mass in *** were conducted for several tunnel shapes and rock support *** obtained for the distribution of failure zones,and stress and displacement felds around the tunnel were compared to select the best tunnel shape and support pattern to achieve the optimum stability conditions.
The miscibility of blends of poly(butylene terephthalate) and poly(bisphenol A-carbonate) was investigated using differential scanning calorimetry. Contrary to previously reported data, PBT and PC were found to be alm...
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The miscibility of blends of poly(butylene terephthalate) and poly(bisphenol A-carbonate) was investigated using differential scanning calorimetry. Contrary to previously reported data, PBT and PC were found to be almost completely immiscible over the entire compostion range studied. The minor change in Tg's observed for samples quenched form the melt can be attributed to transesterification at elevated temperatures. The melting behavior and normalized enthalpy of fusion are somewhat dependent on composition but the behavior is erratic.
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