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Synthesis of nanocrystals of gadolinium carbonate by reaction crystallization.
He, Xin-Kuai,Shin, Dongmin,Kim, Woo-Sik American Scientific Publishers 2012 Journal of Nanoscience and Nanotechnology Vol.12 No.3
<P>The formation of nano-sized crystals of gadolinium carbonate via reaction crystallization was studied in a semi-batch crystallizer using gadolinium chloride and ammonium hydrogen carbonate as the reactants. The gadolinium carbonate crystals were formed by the aggregation of primary particles sized about 5 nm. Thereby, the crystallization parameters acting directly on the aggregation of the primary particles, such as the reactant concentrations, non-stoichiometry of the reactants, solution pH, acoustic energy, and agitation speed, were mechanistically investigated. As such, increasing the reactant concentrations enhanced the crystal size due to higher nucleation of the primary particles for the aggregation. Non-stoichiometric reactant concentrations resulted in a significant reduction of the crystal size, due to the adsorption of the excess species on the primary particles. Similarly, the surface charge of the primary particles depended on the solution pH. Thus, the crystal size was reduced when the pH deviated from the neutral point. The acoustic cavitation of the ultrasound was much more effective than the turbulent fluid motion of the agitation in inhibiting the primary particle aggregation. Thus, the crystal size was remarkably reduced, even at a low acoustic energy of 6 watts.</P>
Wettability contrast on the surface of CuO nanostructures for highly efficient fog harvesting
He Wen-xin,Jin Lian-lian,Ma Xiu-jia,Li Xiao,Li Jia,Wang Xue-wei 한국물리학회 2023 Current Applied Physics Vol.53 No.-
Fog collection can provide a sustainable and efficient method for solving the shortage of water resources. In this article, CuO nanostructures were designed and synthesized on the Cu mesh by a one-step oxidation method and used to collect water from fog. Their morphology and surface wettability are characterized through scanning electron microscopy and dynamic contact angle measuring device, while the process of fog collection is investigated by a high-speed camera. The fog collection efficiency depends on the microstructure of the sample surface, which could be well controlled by adjusting the reaction temperature. Compared with CuO nanoneedles and CuO nanowire clusters, CuO nanosheets promote the rapid falling of liquid droplets, improving the fog harvesting efficiency, which can achieve 3168 mg/cm2 within 120 s. CuO nanosheets have ultra-low adhesion due to high roughness and high air restraint ability, accelerating the transport of water droplets and reducing the re-evaporation of water droplets.
Acoustic Effect on Induction of Cerium Carbonate in Reaction Crystallization
He, Xin-Kuai,Kim, Rayoung,Shin, Dongmin,Kim, Woo-Sik The Society of Chemical Engineers, Japan 2012 Journal of chemical engineering of Japan Vol.45 No.4
<P>The influence of ultrasonication and agitation on the induction of nucleation in the reaction crystallization of cerium carbonate has been investigated in a semi-batch crystallizer. When the cerium chloride and sodium carbonate reactants are constantly injected, the induction time depends significantly on ultrasonication and agitation. Due to the acoustic cavitation of ultrasonication promoting micromixing of the reactants, the induction time of cerium carbonate is markedly reduced. Simultaneously, the acoustic cavitation appears to reduce the energy barrier of nucleation, inducing nucleation at a lower supersaturation level than with the turbulent fluid motion of agitation. However, the acoustic stream of ultrasonication does not promote the induction of nucleation. Meanwhile, agitation also facilitates the induction of nucleation due to turbulent mixing of the reactants. The micromixing resulting from agitation meant the supersaturation in the solution increases rapidly when increasing the agitation speed, thereby reducing the induction time. The influence of ultrasonication and agitation on the induction of nucleation has also been compared in terms of the energy dissipation. With the same energy dissipation, ultrasonication is much more effective than agitation for induction, possibly due to its unique feature of acoustic cavitation.</P>
He, Xin-Feng,Xu, Yong-Chun,He, Zhen The Youngnam Mathematical Society 2011 East Asian mathematical journal Vol.27 No.1
In this paper, we consider an iterative scheme for finding a common element of the set of fixed points of a asymptotically quasi nonexpansive mapping and the set of solutions of the variational inequality for an inverse strongly monotone mapping in a Hilbert space. Then we show that the sequence converges strongly to a common element of two sets. Using this result, we consider the problem of finding a common fixed point of a asymptotically quasi-nonexpansive mapping and strictly pseudocontractive mapping and the problem of finding a common element of the set of fixed points of a asymptotically quasi-nonexpansive mapping and the set of zeros of an inverse-strongly monotone mapping.
Xin-feng He,Yong-chun Xu,Zhen He 영남수학회 2011 East Asian mathematical journal Vol.27 No.1
In this paper, we consider an iterative scheme for finding a common element of the set of fixed points of a asymptotically quasi-nonexpansive mapping and the set of solutions of the variational inequality for an inverse strongly monotone mapping in a Hilbert space. Then we show that the sequence converges strongly to a common element of two sets. Using this result, we consider the problem of finding a common fixed point of a asymptotically quasi-nonexpansive mapping and a strictly pseudocontractive mapping and the problem of finding a common element of the set of fixed points of a asymptotically quasi-nonexpansive mapping and the set of zeros of an inverse-strongly monotone mapping.
ON THE EXISTENCE OF SOLUTIONS OF EXTENDED GENERALIZED VARIATIONAL INEQUALITIES IN BANACH SPACES
He, Xin-Feng,Wang, Xian,He, Zhen The Youngnam Mathematical Society 2009 East Asian mathematical journal Vol.25 No.4
In this paper, we study the following extended generalized variational inequality problem, introduced by Noor (for short, EGVI) : Given a closed convex subset K in q-uniformly smooth Banach space B, three nonlinear mappings T : $K\;{\rightarrow}\;B^*$, g : $K\;{\rightarrow}\;K$, h : $K\;{\rightarrow}\;K$ and a vector ${\xi}\;{\in}\;B^*$, find $x\;{\in}\;K$, $h(x)\;{\in}\;K$ such that <Tx-$\xi$, g(y)-h(x)> $\geq$ 0, for all $y\;{\in}\;K$, $g(y)\;{\in}\;K$. [see [2]: M. Aslam Noor, Extended general variational inequalities, Appl. Math. Lett. 22 (2009) 182-186.] By using sunny nonexpansive retraction $Q_K$ and the well-known Banach's fixed point principle, we prove existence results for solutions of (EGVI). Our results extend some recent results from the literature.
He, Xin-Feng,Xu, Yong-Chun,He, Zhen The Youngnam Mathematical Society Korea 2008 East Asian mathematical journal Vol.24 No.1
The approximate solvability of a generalized system for non-linear variational inequality in Hilbert spaces was studied, based on the convergence of projection methods. But little research was done in Banach space. The primary reason was that projection mapping lacked preferably property in Banach space. In this paper, we introduced the generalized projection methods. By using these methods, the results presented in this paper extended the main results of S. S. Chang [3] from Hilbert spaces to Banach space.
A Four-dimensional (4D) Cosmology Model from a 5D Einstein Manifold Reduction
Xin-He Meng,Jie Ren,Hong-Guang Zhang 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.56 No.5
A five-dimensional Einstein equation with its right-hand side empty, one of the simplest extended gravity models by one more spatial dimension, induces a four-dimensional cosmological model accordingly,which suggests that the matter in the Universe originates from the one extra dimension. We consider the case in which a cosmological constant Λ exists in the 5D Universe and obtain exact solutions for Λ > 0 and Λ < 0. In the 5D Universe with a cosmological constant, not only can it be naturally reduced to the power-law Λ Cold Dark Matter (Λ CDM) model for the 4D real Universe,but also the arbitrary functions and constants in the metric are endowed with explicit physical meanings.