No abstract

No abstract

The question of whether the metal chalcogenides (phosphides) that have been acknowledged to be efficient materials for bifunctional electrocatalysts really perform as the active species or just “pre-catalysts” has been debated. Herein, a series of operando measurements, including in situ X-ray absorption spectroscopy, liquid-phase transmission electron microscopy, and in situ Raman spectroscopy, were conducted to unravel in real time the structural and chemical stability of P-substituted CoSe2 electrocatalysts under both hydrogen and oxygen evolution reactions (HER and OER, respectively) in an alkaline electrolyte. It can be conclusively revealed that, in an alkaline electrolyte, the P-substituted CoSe2 electrocatalyst was acting as the “pre-catalyst” rather than the real reactive species. The introduction of phosphorus is speculated to generate more vacancies or defects around Co cations in the initial CoSe2 and considerably facilitates the structural transformation into the “real reactive species”, such as metallic cobalt (for HER) and cobalt oxyhydroxide (for OER).

No abstract

No abstract

The distribution of soil inorganic phosphorus in soils was found to measure the degree of chemical weathering, the chemical weathering sequence being calcium phosphate, aluminium phosphate, iron phosphate, and occluded phosphate. The latter category includes reductant soluble iron phosphate and aluminium-iron phosphate occluded in iron oxides. For example, three horizons of one Chernozem profile, a Dark Brown soil, and the calcareous C, horizon of a Grey-Brown Podzolic soil containqd 68-95 per cent. of their inorganic phosphorus in the form of calcium phosphate, the other forms decreasing exponentially in the sequence. The inorganic phosphorus of two Latosols increased exponentially in the order calcium phosphate (I yo), aluminium phosphate (0-3 yo), iron phosphate (10-13 %), and occluded (reductant soluble) phosphate (66-78%). Three samples of podzolized soils contained intermediate, sigmoidal distributions of the four phosphates.In two Miami silt loam profiles, the 0-002 N H,SO,-extractable-phosphorus test was much higher in the subsoils down to 3+ ft. than in the surface soil, and was correlated mostly with the calcium-phosphate content, somewhat with aluminium and iron phosphate, and none at all with occluded phosphates which constituted a high percentage of the total phosphorus. The higher content of available phosphorus in the subsoils and release of phosphorus in the surface soil by decrease of A1 and Fe activity through liming most probably explain the lack of crop response to added phosphate fertilizer even though the surface soil had a low phosphorus test.Application of phosphate fertilizer to Almena silt loam greatly increased the amount of aluminium and iron DhosDhate at three lime levels : onlv a slight increase of calcium phosphate occurred; at tge highest lime level. The amount of occluded phosphate remained unchanged by liming or fertilization. The relatively small increase of calcium phosphate through phosphate application is attributable partly to crop removal but is shown to be due mostly to formation of the less soluble iron and aluminium phosphates.

Abstract. In numerical computations, unstructured grids can be used easily to fit computational domains involving complex geometries. The method of spacetime conservation element and solution element (CE/SE method) [i,2] can be used in conjunction with unstructured grids. In this paper, the procedure of developing a non-splitting unstructured-triangular-mesh Euler solver based on the CE/SE method is described. Numerical examples involving complex features of shock waves are presented to show that the CE/SE method works very well even for unstructured triangular grids. IntroductionThe CE/SE method is a new numerical framework that was conceived and formulated from basic physical principles to overcome several major limitations of the traditional methods, i.e., finite difference, finite volume, finite element, and spectral methods. It was built from ground zero and aimed to be a simple, coherent, robust, and general-purpose numerical method for accurate and efficient simulation of CFD problems. Various flow problems have previously been solved by using the CE/SE method. For example, some complex physical phenomena that involve shock waves and their reflections, rarefactions, and interactions with bodies or other waves have been successfully simulated using CE/SE Euler solvers based on structured grids(uniform or nonuniform) [3,4]. Previous work in the application of the CE/SE method to computational aeroacoustics [5], chemical reacting flows [6], and dam-break and hydraulic jump [7] has demonstrated the robustness and efficiency of this method.To further broaden the applicability of the CE/SE method, the 2-D CE/SE Euler solver based on an unstructured mesh is developed in this paper. The major difference between the CE/SE Euler solver based on structured and unstructured meshes is described. Two representative numerical results are presented and compared with experimental data to show the per-

No abstract