Selective and competitive removal of three basic dyes from single,binary and ternary systems in aqueous solutions: A combined experimental and theoretical study

The present study evaluates the selective and competitive adsorption of three basic dyes, namely, Basic blue 9 (BB9), Basic blue 41 (BB41) and Basic yellow 28 (BY28) from single, binary and ternary solutions onto natural safiot clay (NSC). For this, the effect of various parameters such as initial pH, initial dye concentration, adsorbent dose and temperature of the solution was studied and examined in a batch mode. The tested adsorbent was characterized by X-ray fluorescence (XRF), Scanning Electron Microscopy (SEM), Dispersive X-ray spectroscopy (EDX), Fourier Transform Infrared (FT-IR) and X-Ray Diffraction (XRD). XRF results indicate high percentages of SiO₂ (47.44%) and Al₂O₃ (31.24%). X-ray diffraction diffractogram identified kaolinite as the main mineral phase in the presence of quartz, illite, calcite, and dolomite. The adsorption data were examined by Langmuir, Freundlich and Dubinin-Radushkevich isotherms. It was found that for single, binary and ternary systems the results indicated that Langmuir model provided the better correlation of experimental data. The experimental results obtained demonstrate high adsorption efficiency of dyes in the mono and multi systems by NSC. DFT calculations show that BB9 (ω = 6.18) is more electrophilic than BB41 (ω = 4.10) and BY28 (ω = 2.60) which indicates that BB9 is adsorbed first and favored compared to BB41 and BY28. Moreover, Molecular dynamics (MD) and Monte Carlo (MC) simulations are used as a powerful tool to provide a better theoretical scenario for understanding the mode of adsorption on the natural safiot clay (NSC).     

基于纤维随机分布的单向复合材料拉伸破坏过程模拟

单向复合材料的极限拉伸强度受纤维强度变化和纤维随机分布的影响。本文提出了一种合理的纤维随机分布假设,并以此建立了剪滞数值模型。利用蒙特卡罗模拟方法结合现有模型分析了单向复合材料的拉伸失效过程,得到极限拉伸强度。与文献模型相比较的结果表明,本文的模型结果更理想。     

Ge/Pb/Si(111)生长中Ge原子沿团簇边缘扩散的三维Monte-Carlo模拟

用动态Monte-Carlo方法对Ge在单层表面活性剂Pb覆盖的Si(111)表面上沿团簇边缘扩散进行三维模拟.重点讨论Ge原子是否沿团簇边缘扩散,沿边缘扩散时的最大扩散步数及最近邻原子数对三维生长的影响,并计算薄膜表面粗糙度研究三维生长模式.模拟表明Ge沿团簇边缘扩散的行为对薄膜生长模式的影响很大,同时讨论了ES势对三维生长模式的影响.     

光在苹果组织中传输的光谱特性

用Monte-Carlo方法模拟研究了激光波长632 nm与750 nm的高斯光束在苹果组织中传输的吸收、散射光谱特性。结果表明：高斯光束特殊的能量分布特性对激光在苹果组织中的传播有重要的影响,苹果组织对750 nm激光的反射、吸收、透射都较低,有更多的光子在组织内部与组织相作用,能够更清楚的反映组织内部信息。因此,在生物组织中近红外光波的传输性比较好,便于应用于研究生物组织。     

ON THE POWER OF STANDARD INFORMATION FOR APPROXIMATION IN RANDOMIZED SETTING

This article considers weighted approximation of multivariate function inreproducing kernel Hilbert space, and gives a relation between nth minimal errors for standard and linear information in the randomized setting. Using this relation we canestimate the nth minimal error for standard information by the nth minimal errorfor linear information, and study the tractability and strong tractability for these twoclasses of information.     

不同模式耦合下偏振模色散几率分布的研究

研究了偏振模色散的统计特性,在不同模式耦合条件下,应用蒙特-卡罗方法模拟偏振模色散矢量的几率分布,并对模拟结果进行了函数拟合。发现随着耦合次数增加差分群时延的几率分布从一个类似δ函数分布逐渐过渡到麦克斯韦分布;在一定的耦合下,几率分布可以呈现高斯分布。对偏振模矢量的两个方向余弦进行统计分析,发现随着耦合次数的增加,偏振模矢量两个方向余弦函数的分布从高斯分布和δ函数分布都变为均匀分布。     

Bayesian uncertainty quantification in inverse modeling of electrochemical systems

This present study proposes a novel approach to quantifying uncertainties of constitutive relations inferred from noisy experimental data using inverse modeling. We focus on electrochemical systems in which charged species (e.g., Lithium ions) are transported in electrolyte solutions under an applied current. Such systems are typically described by the Planck-Nernst equation in which the unknown material properties are the diffusion coefficient and the transference number assumed constant or concentration-dependent. These material properties can be optimally reconstructed from time- and space-resolved concentration profiles measured during experiments using the magnetic resonance imaging (MRI) technique. However, as the measurement data is usually noisy, it is important to quantify how the presence of noise affects the uncertainty of the reconstructed material properties. We address this problem by developing a state-of-the-art Bayesian approach to uncertainty quantification in which the reconstructed material properties are recast in terms of probability distributions, allowing us to rigorously determine suitable confidence intervals. The proposed approach is first thoroughly validated using “manufactured” data exhibiting the expected behavior as the magnitude of noise is varied. Then, this approach is applied to quantify the uncertainty of the diffusion coefficient and the transference number reconstructed from experimental data revealing interesting insights. © 2018 Wiley Periodicals, Inc.     

Exploration of large amplitude motions in the Ca+Ar2 complex

ABSTRACT

We present a theoretical study of the ground electronic state potential of the Ca⁺Ar₂ complex and of its photoabsorption spectra, simulated at temperatures ranging between 20 and 220?K. These calculations exploit a Monte-Carlo (MC) method, based on a one-electron pseudo-potential approach. A pairwise additive potential fitted to coupled cluster ab initio points, is used to model the Ca⁺Ar₂ complex. Our study shows that the most stable form of Ca⁺Ar₂ is a bent C_2v structure, whereas the linear isomer is located at around 90?±?10?cm^?1 above in energy. The analysis of the photoabsorption spectra establishes that a structural transition from bent Ca⁺Ar₂ to linear ArCa⁺Ar occurs at T～100?K. Trends in binding energies of both isomers, bond lengths and bond angles are also discussed. Molecular orbital overlaps provide an explanation for the order of stability between the bent and linear structures.     

Classical density functional theory meets Monte-Carlo simulations

ABSTRACT

Typically the quality of an approximate density functional is evaluated by a direct comparison of its predictions in a given test case to exact data obtained by computer simulations. An important example for such an approach is the test of equilibrium structure of a simple fluid as measured by the pair distribution function g(r) or the cavity correlation function y(r). However, the combination of exact density profiles and the analytical structure of density functional theory allows one to determine and potentially improve the quality of a functional in a more sophisticatedway.