Combining linear polarization spectroscopy and the Representative Layer Theory to measure the Beer–Lambert law absorbance of highly scattering materials

Visible and Near Infrared (Vis–NIR) Spectroscopy is a powerful non destructive analytical method used to analyze major compounds in bulk materials and products and requiring no sample preparation. It is widely used in routine analysis and also in-line in industries, in-vivo with biomedical applications or in-field for agricultural and environmental applications. However, highly scattering samples subvert Beer–Lambert law's linear relationship between spectral absorbance and the concentrations. Instead of spectral pre-processing, which is commonly used by Vis–NIR spectroscopists to mitigate the scattering effect, we put forward an optical method, based on Polarized Light Spectroscopy to improve the absorbance signal measurement on highly scattering samples. This method selects part of the signal which is less impacted by scattering. The resulted signal is combined in the Absorption/Remission function defined in Dahm's Representative Layer Theory to compute an absorbance signal fulfilling Beer–Lambert's law, i.e. being linearly related to concentration of the chemicals composing the sample. The underpinning theories have been experimentally evaluated on scattering samples in liquid form and in powdered form. The method produced more accurate spectra and the Pearson's coefficient assessing the linearity between the absorbance spectra and the concentration of the added dye improved from 0.94 to 0.99 for liquid samples and 0.84–0.97 for powdered samples.     

SCR催化剂碱(土)金属中毒的研究进展

在选择性催化还原(SCR)烟气脱硝系统中,催化剂碱(土)金属中毒和再生受到广泛关注。本文综述了SCR脱硝催化剂碱(土)金属中毒的失活机理及基于分子水平上碱金属中毒的研究新思路,并根据催化剂的各种失活机理,有针对性地综述了提高催化剂抗碱金属中毒的途径及中毒催化剂的再生方法。     

弹塑性有限变形的拟流动理论

本文提出一种弹塑性有限变形的拟流动理论。该理论从正交性法则出发，通过引入“拟弹性模量”和模量衰减函数并改进应变率的弹塑性分解，实现了由有限变形Ｐｒａｎｄｔｌ－Ｒｅｕｓｓ流动理论（Ｊ２Ｆ）向基于非正交法则的率形式形变理论（Ｊ２Ｄ）的合理的光滑过渡；并适用于初始及后继各向异性变形分析。在特殊条件下，可退化为Ｊ２Ｆ、Ｊ２Ｄ理论以及由任意各向异性屈服函数描述的流动理论。将该理论用于韧性金属平面应力／应变拉伸失稳与变形局部化的有限元模拟，并与理论分析及实验结果相比较，表明了本文理论的正确性。     

Viscosity of liquid suspensions with fractal aggregates: Magnetic nanoparticles in petroleum colloidal structures

New physical model is presented resulting in a simple formula for the dependence of viscosity η of colloidal liquid solution on the shear rate G applicable to a wide variety of systems including complex natural liquids like petroleum. The principal point of the model is the fractal nature of colloid particle aggregates present in the liquid. Such aggregates are experimentally detected now in non-Newtonian liquids. The model is based on calculation of energy loss on colloidal particle aggregate of fractal structure localized in the flow of liquid with shear rate. We have performed the viscosity measurement experiments which confirmed successfully the developed physical model. Also, we demonstrate experimentally that petroleum colloidal particles and magnetic iron oxide nanoparticles can form composite fractal-like aggregates in natural petroleum materials. Our model can explain both the non-Newtonian properties of petroleum and sensitivity of petroleum viscosity to external magnetic fields.     

Insuring against loss of evidence in game-theoretic probability

Statistical testing can be framed as a repetitive game between two players, Forecaster and Sceptic. In each round, Forecaster sets prices for various gambles, and Sceptic chooses which gambles to make. If Sceptic multiplies by a large factor the capital he puts at risk, he has evidence against Forecaster’s ability. His capital at the end of each round is a measure of his evidence against Forecaster so far. This can go up and then back down. If you report the maximum so far instead of the current value, you are exaggerating the evidence against Forecaster. In this article, we show how to remove the exaggeration. Removing it means systematically reducing the maximum in such a way that a rival to Sceptic can always play so as to obtain current evidence as good as Sceptic’s reduced maximum. We characterize the functions that can achieve such reductions. Because these functions may impose only modest reductions, we think of our result as a method of insuring against loss of evidence. In the context of an actual market, it is a method of insuring against the loss of what an investor has gained so far.     

Experimental investigation of the difference in B-term dominated band broadening between fully porous and porous-shell particles for liquid chromatography using the Effective Medium Theory

The difference in B-term diffusion between fully porous and porous-shell particles is investigated using the physically sound diffusion equations originating from the Effective Medium Theory (EMT). Experimental data of the B-term diffusion obtained via peak parking measurements on six different commercial particle types have been analyzed (3 porous and 3 non porous). All particles were investigated using the same experimental design and test analytes, over a very broad range of retention factor values. First, the B-term reducing effect of the solid core (inducing an additional obstruction compared to fully porous particles) has been quantified using the Hashin-Shtrikman expression, showing that the presence of a solid core can account for a reduction of about 11% when the core diameter makes up 63% of the total particle diameter (Halo and Poroshell-particles) and a reduction of 16% when the core diameter makes up 73% (Kinetex). Remaining differences can be attributed to differences in the microscopic structure of the meso-porous material (meso-pore diameter, internal porosity or relative void volume). The much lower B-term diffusion of Halo and Kinetex particles compared to the fully porous Acquity particles (some 20-40% difference, of which about 10-15% can be attributed to the presence of the solid core) can hence largely be attributed to the much smaller internal porosity and the smaller pore size of the meso-porous material making up the shell of these particles.     

Hypergraph list coloring and Euclidean Ramsey theory

A hypergraph is simple if it has no two edges sharing more than a single vertex. It is s‐list colorable (or s‐choosable) if for any assignment of a list of s colors to each of its vertices, there is a vertex coloring assigning to each vertex a color from its list, so that no edge is monochromatic. We prove that for every positive integer r, there is a function d_r(s) such that no r‐uniform simple hypergraph with average degree at least d_r(s) is s‐list‐colorable. This extends a similar result for graphs, due to the first author, but does not give as good estimates of d_r(s) as are known for d₂(s), since our proof only shows that for each fixed r ≥ 2, d_r(s) ≤ 2 We use the result to prove that for any finite set of points X in the plane, and for any finite integer s, one can assign a list of s distinct colors to each point of the plane so that any coloring of the plane that colors each point by a color from its list contains a monochromatic isometric copy of X. © 2011 Wiley Periodicals, Inc. Random Struct. Alg., 2011     

二氧化铬阴离子光电子能谱的理论研究

凭借密度泛函理论,采用不同基组对中性分子CrO2的基态（ 3B1）以及阴离子CrO2‾的基态（ 4B 1）进行几何优化和振动频率分析;应用量化计算得到的力常数及结构和光谱参数,基于推得的两维四模Franck-Condon重叠积分的代数表示,对CrO2 ( 3B1)－CrO2‾ ( 4B1) 的光脱附过程进行Franck-Condon分析和光谱模拟,理论上得到光电子能谱的谱线相对强度及振动结构分布,理论谱与实验测得的二氧化铬阴离子光电子能谱达到一致,并对光电子能谱的振动结构进行归属及热带分析;另外,在光谱模拟过程中通过迭代Franck-Condon分析过程,推得CrO2‾（ 4B1）与CrO2（ 3B1）平衡几何结构之差：ΔR(Cr-O)= 0.05Å,Δ(O-Cr-O)=12o.     

Nin(n=1-9)小团簇的密度泛函理论研究

采用密度泛函理论(DFT)方法对Nin(n=1-9)团簇的结构, 稳定性和磁性进行了详细的研究. 得到了一些以前文献中没有提到的稳定结构, 并与其它方法得到的结构进行了比较, 得到的最稳定结构与实验结果相一致. 团簇能量的二阶差分、分裂能、HOMO-LUMO能隙随团簇尺寸的演化都没有表现出明显的奇偶振荡行为, 但在n=5、7时均有较大的值, 说明相对应的团簇具有较高的稳定性、较低的化学活性. 团簇磁性的研究表明团簇的平均每原子磁矩随团簇尺寸的增加有一定振荡, 但有逐渐减小的趋势, n≥5时团簇的构型对团簇磁性的影响较小.     

Hyperthermal cluster-surface scattering

Using molecular-dynamics simulation, we study the processes occurring after impact of clusters on a rigid wall. Comparing the impact of model clusters consisting of 13 atoms, or of 13 diatomic molecules with varied bond strength, the systematics in the results of the collision process are investigated. Four regimes of impact-induced cluster fragmentation are identified: intact reflection, shattering into large fragments, complete fragmentation, and molecule dissociation. The effect of the number of degrees of freedom activated in the collision on the translational and internal energies of the reflected fragments is discussed in detail. As a rule, with increasing number of degrees of freedom which can be activated in the collision, the translational energy sinks. On the other hand, for weak intramolecular bonding, intramolecular vibrations are easily excited at small impact energies, reducing the resulting translational energy. The presence of even a very weak attractive well epsilon_w at the surface has a major influence on the sticking behavior of the clusters — and hence also on the absolute reflected energies — even at impact energies E₀ ≫ epsilon_w.