A nickel oxide nanoflakes/reduced graphene oxide composite and its high-performance lithium-storage properties

Journal of Solid State Electrochemistry - Since conventional graphite-based anode possesses a low capacity, seeking for high-capacity anode candidates becomes significant for constructing emerging...     

Opposed flame spread over folded PMMA plate with various internal angles

The effect of the internal angle on downward flame spread over a thick folded plate is experimentally investigated in this study. The lateral side of a thermoplastic plate is cut at desired angles and two of these plates are welded to form a single folded sample. All the faces other than the front and two 5-mm areas of the front face from each side were coated to inhibit the combustion. Experiments are conducted for various folded plates of different angles, 60°, 90°, 120°, and 180°. Following ignition at the upper edge of the sample, the opposed flame spread on the front face is observed and the flame spread rate at various positions is quantified by image analysis. The flame spreads more rapidly at the folding edge, while the other parts then accelerate to catch up with the corner spread and, eventually, all the parts across the width achieve the same flame spread rate as the folding edge. This result indicates that the flame spread rate at the folding edge is the characteristic value which represents the steady-state of the system of interest. A simple model is developed considering change of heated volume against the flame and change of the induced flow velocity due to the geometry. The former effect is formulated from geometrical consideration in the vicinity of the edge, while the latter is formulated based on an experimental fact that the flame height is inversely proportional to the internal angle. A prediction formula of the flame spread rate at the folding edge is established by modifying the conventional one for the flat plate. The calculated flame spread rate shows reasonably good agreement with the experimental data. This study helps fundamental understanding of the flame spread behavior of practical combustibles such as pillars or rods with various cross-sectional shapes.     

Analysis of model dimensionality,particle shrinkage,boundary layer reactions on particle-scale modelling of biomass char conversion under pulverized fuel combustion conditions

In this work, the effects of model dimensionality, particle shrinkage, and boundary layer reactions on particle-scale modelling of biomass char conversion under pulverized fuel combustion conditions have been analysed by using six models: zero-dimensional models with constant particle size (0D_Cons) or shrinking particle size (0D_SPM), one-dimensional models with/without considering particle shrinkage (1D_Cons/1D_SPM), and 1D_Cons and 1D_SPM with considering boundary layer reactions (1D_Cons_BH and 1D_SPM_BH). A comparison with existing experimental data shows that the 1D_SPM_BH model with consideration of intra-particle heat and mass transfer, particle shrinkage, and boundary layer reactions is an appropriate model to describe biomass char conversion over a wide range of conditions. The 0D_Cons model is a good approximation for the conditions of small particle size (< 1 mm) at 1273–1473 K, but overestimates the char conversion rate for larger biomass char particle or at high temperatures (regime III). The 0D_SPM model gives a reasonable prediction on char conversion time but predicts a larger contribution of reaction between char and O₂ as compared to the 1D_SPM_BH model. The consideration of intra-particle heat and mass transfer in particle-scale modelling (1D_Cons and 1D_SPM) is beneficial to improving the model prediction of char conversion time and the contributions of char oxidation and gasification reactions. The boundary layer reactions have a significant effect on the prediction of char conversion for large particles (> 1 mm) and high temperatures (> 1473 K). An implication for the selection of a particle-scale model in CFD modelling is also given.     

Effect of coral powder and ground-granulated blast‑furnace slag on the hydration behavior of cement paste

Journal of Thermal Analysis and Calorimetry - Coral wastes are produced during the construction of island. The use of coral wastes in concrete is beneficial to economy and environment. Coral waste...     

Precisely installing gold nanoparticles at the core/shell interface of micellar assemblies of triblock copolymers

Two reduction-cleavable ABA triblock copolymers possessing two disulfide linkages, PMMA-ss-PMEO₃MA-ss-PMMA and PDEA-ss-PEO-ss-PDEA were synthesized via facile substitution reactions from homopolymer precursors, where PMMA, PMEO₃MA, PDEA, and PEO represent poly(methyl methacrylate), poly(tri(ethylene glycol) monomethyl ether methacrylate, poly(2-(diethylamino)ethyl methacrylate), and poly(ethylene oxide), respectively. Spherical micelles were obtained through supramolecular self-assembly of these two triblock copolymers in aqueous solutions. The resultant micelles with abundant disulfide bonds could serve as soft templates and precisely accommodate gold nanoparticles in the core/shell interface as a result of the formation of Au-S bonds.     

盾构渣土基碳复合陶粒的制备及除磷性能

以固体废弃物地铁盾构渣土、稻草秸秆和氧化镁为主要原料,通过烧结法制备了一种盾构渣土基碳复合陶粒。考察了陶粒吸附磷的主要影响因素及平衡吸附量,并采用模型对实验数据进行拟合分析。结果表明,当盾构渣土、稻草秸秆粉末和氧化镁质量比为7∶2∶1,在最佳烧结条件700℃烧结可得到除磷性能最佳的陶粒。当吸附pH=6.3时,陶粒具有较高的磷吸附性能。吸附在12 h内基本能达到吸附平衡,该过程适合准二级动力学方程。盾构渣土基碳复合陶粒对磷酸盐的吸附符合Temkin等温模型,随温度升高吸附量逐渐增大,40℃下最大吸附量为12.76 mg/g。热力学参数ΔH=5.64 k J/mol0,ΔS=8.00 J/(K·mol)0,ΔG=3.16 k J/mol0,呈吸热、非自发的热力学特征,陶粒吸附磷后可通过2.0 mol/L的氢氧化钠溶液重新解吸回收。