Vibrational spectroscopy in the development of surface hydrophilic elastomer latex (SHEL)

An illustrative example is given to show how various vibrational spectroscopy techniques coupled with two-dimensional (2D) correlation analysis can be effectively utilized in the development of a novel and functional material. Surface-hydrophilic elastomer latex (SHEL) is a material exhibiting rather unusual permanently water-wettable surface feature despite having a soft and rubbery bulk property, which can be successfully analyzed with vibrational spectroscopy. 2D photoacoustic (PAS) IR spectra of a SHEL film indicate the localized surface segregation of long-chain ethoxylate moiety of the oligomeric surfactant used in the preparation of this material. The accumulation of the hydrophilic long-chain ethoxylate produces the high energy polar surface over the hydrophobic bulk phase of SBR copolymer. The persistence of very low water contact angle, even after repeated washing of a SHEL film with an excess amount of water, indicates permanent covalent attachment of long-chain ethoxylate group to the SBR copolymer. 2D Raman spectra generated from the process monitoring of the emulsion copolymerization of SHEL reveal the mechanism of the covalent attachment of long-chain ethoxylate. The reaction involves a separate step of oleyl moiety of the block surfactant reacting with 1,3-butadiene prior to the onset of copolymerization to produce the SBR latex product.     

Efficient computation of operator‐type response sensitivities for uncertainty quantification and predictive modeling: illustrative application to a spent nuclear fuel dissolver model

This work honors the 75th birthday of Professor Ionel Michael Navon by presenting original results highlighting the computational efficiency of the adjoint sensitivity analysis methodology for function‐valued operator responses by means of an illustrative paradigm dissolver model. The dissolver model analyzed in this work has been selected because of its applicability to material separations and its potential role in diversion activities associated with proliferation and international safeguards. This dissolver model comprises eight active compartments in which the 16 time‐dependent nonlinear differential equations modeling the physical and chemical processes comprise 619 scalar and time‐dependent model parameters, related to the model's equation of state and inflow conditions. The most important response for the dissolver model is the time‐dependent nitric acid in the compartment furthest away from the inlet, where measurements are available at 307 time instances over the transient's duration of 10.5 h. The sensitivities to all model parameters of the acid concentrations at each of these instances in time are computed efficiently by applying the adjoint sensitivity analysis methodology for operator‐valued responses. The uncertainties in the model parameters are propagated using the above‐mentioned sensitivities to compute the uncertainties in the computed responses. A predictive modeling formalism is subsequently used to combine the computational results with the experimental information measured in the compartment furthest from the inlet and then predict optimal values and uncertainties throughout the dissolver. This predictive modeling methodology uses the maximum entropy principle to construct an optimal approximation of the unknown a priori distribution for the a priori known mean values and uncertainties characterizing the model parameters and the computed and experimentally measured model responses. This approximate a priori distribution is subsequently combined using Bayes' theorem with the “likelihood” provided by the multi‐physics computational models. Finally, the posterior distribution is evaluated using the saddle‐point method to obtain analytical expressions for the optimally predicted values for the parameters and responses of both multi‐physics models, along with corresponding reduced uncertainties. This work shows that even though the experimental data pertains solely to the compartment furthest from the inlet (where the data were measured), the predictive modeling procedure used herein actually improves the predictions and reduces the predicted uncertainties for the entire dissolver, including the compartment furthest from the measurements, because this predictive modeling methodology combines and transmits information simultaneously over the entire phase‐space, comprising all time steps and spatial locations. Copyright © 2016 John Wiley & Sons, Ltd.     

Combinatorial and approximative analyses in a spatially random division process

For a spatial characteristic, there exist commonly fat-tail frequency distributions of fragment-size and -mass of glass, areas enclosed by city roads, and pore size/volume in random packings. In order to give a new analytical approach for the distributions, we consider a simple model which constructs a fractal-like hierarchical network based on random divisions of rectangles. The stochastic process makes a Markov chain and corresponds to directional random walks with splitting into four particles. We derive a combinatorial analytical form and its continuous approximation for the distribution of rectangle areas, and numerically show a good fitting with the actual distribution in the averaging behavior of the divisions.     

Computer Controlled AAS Scanning Method to Study Flame Atomization Processes

By slightly changing the optical and burner systems of the conventional atomic absorption spectrometer, a computer controlled scanning method has been developed, which enables us to get a picture of absorbance distribution over the entire cross section of the analytical flames quickly, reproducibly and in high resolution. The plotting of different distribution functions obtainable by computerized data processing and the conclusions drawn from them are illustrated with some examples of flame atomization of cobalt and magnesium salts. The newly discovered method, by its reliability and little demand on time, allows the extension of the general applicability of AAS in revealing analytical interference effects and in the study of flame-chemical processes.     

Investigation of a UV-laser generated waveguide in a planar polymer chip using an improved interferometric method

Polymeric integrated-optical waveguides are prepared in a planar polymer chip by UV-laser lithographic methods. The waveguide samples are irradiated by an excimer laser at a wavelength Λ=248 nm with various irradiation parameters (different fluencies and irradiation doses). Mach-Zehnder interferometer is employed and the refractive index depth profiles of the waveguide samples are obtained. This profile covers two regions having exponential and Gaussian shapes. The model field distributions strongly depend on the refractive index of each region. The mode field distribution and the effective mode indices for each region have been calculated on the basis of a theoretical model and the experimentally measured data.     

次线性期望下的一般中心极限定理

受Peng-中心极限定理的启发,本文主要应用G-正态分布的概念,放宽Peng-中心极限定理的条件,在次线性期望下得到形式更为一般的中心极限定理.首先,将均值条件E[X_n]=ε[X_n]=0放宽为|E[X_n]|+|ε[X_n]|=O(1/n);其次,应用随机变量截断的方法,放宽随机变量的2阶矩与2+δ阶矩条件;最后,将该定理的Peng-独立性条件进行放宽,得到卷积独立随机变量的中心极限定理.     

Ideal Free Distribution in Two Patches

In this paper, the formats of Julia sets for a class of nonlinear complex dynamic systems with variable coefficients were studied under certain conditions. For the complex dynamic systems in piecewise cases, we proposed some methods to control the forms of their Julia sets and stable domains analytically. What’s more, we illustrated that our methods worked well by computational simulations. Our work provides a better understanding about how to control the Julia sets of certain complex dynamic systems.     

塑料薄膜撕扯实验在聚合物教学中的应用及讨论

结合新课标要求,揭示塑料薄膜撕扯实验在聚合物教学中的重要性、必要性。通过教学片段设计,发展学生“宏观辨识与微观探析、证据推理与模型认知”化学学科核心素养,并让学生认识物质的性能不仅取决于结构,也取决于生产工艺。并对人教版初、高中化学教材和教参中相关问题展开讨论和解释,以期更好地服务教学。     

Bayesian Analysis of Exafs Data

In this paper we demonstrate the use of Bayesian analysis methods for the analysis of EXAFS data. We will discuss the physical parameters that may be estimated by the method and demonstrate the applicability of the method to Molybdenum coordination compounds.