Aspects of radical cation chemistry and possible applications to coal model compound reactions.

The following manuscript is a description of our efforts over the last five years to investigate and elucidate the chemical parameters and mechanisms that lead to the C-C bond cleavage reactions in organic compounds. Motivation to perform this work was provided by the reactions of certain coal model compounds under coal liquefaction conditions. These coal model compounds were found to cleave the bond connecting the naphthalene ring to the remainder of the molecule and the reactivity was attributed to be due to radical cation behavior. This behavior was different than the reactivity of radical cations of similar phenyl-containing compounds. Our contribution to this field involves the investigation of the C-C bond cleavage reactions of the radical cations of naphthyl-containing compounds. Chapter I illustrates the generation of the radical cations of naphthyl-containing compounds in solution and gas phase and their bond cleavage reactions. Their reactivity was compared to the corresponding reactivity under catalytic conditions. Chapter II examines the general oxidation reactions of the above-mentioned compounds. The purpose was to investigate the effects of counterion on the reactions. The remainder of this chapter is devoted to the investigations of the dehydrogenation reactions of related compounds. There has been interest recently in the development of new and milder dehydrogenating reagents. Three Fe compounds were found to produce the desired dehydrogenation reactivity at relatively low temperatures (130{dollar}\\sp\\circ{lcub}\\rm C{rcub}).{dollar} The final chapter of this manuscript discusses the results and conclusions derived from the sensitized irradiation of a series of esters by a triphenylpyrylium salt and oxygen. These esters were found to undergo C-C bond cleavage reactions and these reactions were found to arise by a oxygen-induced radical chain autoxidation reaction and not by radical cationic behavior as has been proposed in the literature. It is my hope that future work will be devoted to further our understanding of the general oxidations and dehydrogenations of some substrates by Fe compounds. What role does the C10{dollar}\\sb4\\sp{lcub}-{rcub}{dollar} play in these reactions? Is a radical cation intermediate involved here? These are only a few of the potential avenues that can be examined by using this manuscript as a guide. I am sure that there are more unexpected and exciting reactions waiting to be observed in the systems such as those described in this text

Retinal nerve fiber layer thickness measurements in rats with spectral domain-optical coherence tomography.

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Accuracy of depth-integrated nonhydrostatic wave models

Depth-integrated nonhydrostatic models have been wildly used to simulate propagation of waves. Yet, there lacks a well-documented theoretical framework that can be used to assess the accuracy and scope of applications of these models and the related numerical approaches. In this work, we carry out Stokes-type Fourier and shoaling analyses to examine the linear and nonlinear properties of a popular one-layer depth-integrated nonhydrostatic model derived by Stelling and Zijlema (2003). The theoretical analysis shows that the model can satisfactorily interpret the dispersity for linear waves but presents evident divergence for nonlinear solutions even when kd → 0. A generalized depth-integrated nonhydrostatic formulation using arbitrary elevation as a variable is then derived and analyzed to examine the effects of neglecting advective and diffusive nonlinear terms in the previous studies and explore possible improvements in numerical solutions for wave propagation. Compared with the previous studies, the new generalized formulation exhibits similar dispersion relationship and improved shoaling effect. However, no significant improvement is presented for the nonlinear properties, indicating that retaining neglected nonlinear terms may not significantly improve the nonlinear performance of the nonhydrostatic model. Further analysis shows that the nonlinear properties of the depth-integrated nonhydrostatic formulation may be improved by defining variables at one-third of the still water level. However, such an improvement comes at the price of decreasing accuracy in describing dispersion and shoaling properties

A new multilayer nonhydrostatic formulation for surface water waves

This work presents a new multilayer nonhydrostatic formulation for surface water waves. The new governing equations define velocities and pressure at an arbitrary location of a vertical layer and only contain spatial derivatives of maximum second order. Stoke-type Fourier and shoaling analyses are carried out to scrutinize the mathematical properties of the new formulation, subsequently optimizing the representative interface and the location to define variables in each layer to improve model accuracy. Following the analysis, the one-layer model exhibits accurate linear and nonlinear characteristics up to kd = I, demonstrating similar solution accuracy to the existing second-order Boussinesq-type models. The two-layer model with optimized coefficients can maintain its linear and nonlinear accuracy up to kd = 4I, which boasts of better solution accuracy a larger application range than most existing fourth-order Boussinesq model and two-layer Boussinesq models. The three-layer model presents accurate linear and nonlinear characteristics up to kd = 10Ï, effectively removing any shallow water limitation. The current multilayer nonhydrostatic water wave model does not predefine the vertical flow structures, and more accurate vertical velocity distributions can be obtained by considering the velocity profiles in coefficient optimization

Meta-analysis of optical lowcoherence reflectometry versus partial coherence interferometry biometry

This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/A meta-analysis to compare ocular biometry measured by optical low-coherence reflectometry (Lenstar LS900; Haag Streit) and partial coherence interferometry (the IOLMaster optical biometer; Carl Zeiss Meditec). A systematic literature search was conducted for articles published up to August 6th 2015 in the Cochrane Library, PubMed, Medline, Embase, China Knowledge Resource Integrated Database and Wanfang Data. A total of 18 studies involving 1921 eyes were included. There were no statistically significant differences in axial length (mean difference [MD] 0 mm; 95% confidence interval (CI) −0.08 to 0.08 mm; p = 0.92), anterior chamber depth (MD 0.02 mm; 95% CI −0.07 to 0.10 mm; p = 0.67), flat keratometry (MD −0.05 D; 95% CI −0.16 to 0.06 D; p = 0.39), steep keratometry (MD −0.09 D; 95% CI −0.20 to 0.03 D; p = 0.13), and mean keratometry (MD −0.15 D; 95% CI −0.30 to 0.00 D; p = 0.05). The white to white distance showed a statistically significant difference (MD −0.14 mm; 95% CI −0.25 to −0.02 mm; p = 0.02). In conclusion, there was no difference in the comparison of AL, ACD and keratometry readings between the Lenstar and IOLMaster. However the WTW distance indicated a statistically significant difference between the two devices. Apart from the WTW distance, measurements for AL, ACD and keratometry readings may be used interchangeability with both devices