Critical Evaluation of Rate Constants and Equilibrium Constants of Hydrogen Peroxide Photolysis in Acidic Aqueous Solutions Containing Chloride Ions

Equilibrium constants and rate constants involving Cl⋅(aq),Cl⋅(aq), Cl−,Cl−, Cl2−⋅(aq), HO⋅,Cl2−⋅(aq),HO⋅, H2O,H2O, and H2O2(aq)H2O2(aq) determined at 297±2 K297±2K in the aqueous phase are updated and evaluated. Most of the rate constants and equilibrium constants are obtained by either pulse radiolysis or laser flash photolysis. The recommended values of rate constants and equilibrium constants are achieved by un-weighted averaging of the reliable experimental measurements. © 2004 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87747/2/747_1.pd

Comparative Analysis of Polyhedral Oligomeric Silsesquioxane (POSS) Using ToF-SIMS

Polyhedral Oligomeric Silsesquioxane, often referred to as POSS, is an important type of nanostructured chemical compound because of its properties which bridge the gap between ceramic and organic materials. POSS has a variety of applications as an additive, a plastic, as well as a preceramic. Some more detailed examples of these categories are thermal modifiers when used as an additive, medical material when used as a plastic, and cladding or electronic coating when used as a preceramic. The two main valuable features of POSS chemical technology are how large the molecule building block is and what the intermediate composition is between SiO2 and R2SiO. Such information is crucial in POSS design and synthesis. Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) is used to study POSS to provide more insight in its molecular structure and functioning group. Four POSS samples with different Si-O bond and functioning groups were analyzed. SIMS is widely used to analyze the surfaces by exposing the surface of the specimen with a primary focused ion beam and then analyzing the secondary ions which were ejected. POSS powder samples were analyzed in this study. Both positive ion and negative ion spectral plots were analyzed to obtain a more thorough understanding of characteristic peaks of the POSS samples. Peaks were then identified by searching for compounds masses and the intensity of these peaks reconfirmed the existence of that compound in the examined sample. The results of this comparative analysis revealed that each POSS sample had unique molecular fragments indicative of its structure and building block. Spectral principal component analysis (PCA) was conducted to identify the key peaks differentiating these samples. Our initial SIMS analysis demonstrates that useful structural information can be gained using SIMS

The Effects of Electrolyte Chemical Composition, Concentration and pH on the Electrochemical Redox Reactions

Electrolyte composition, concentration, pH, ionic strength, and temperature have long been known to play a role in the interface of the electrode-electrolyte. However, detailed studies are not sufficient. Cyclic voltammetry (CV) is a widely used electrochemical technique for obtaining qualitative information in electroanalysis. CV is often the first experiment performed in an electrode surface in an electrochemical study. It measures the number of electrons transferred and intermediates formed during oxidation-reduction (redox) reactions by observing its current, intensity and position of peak potential with applied voltage. This is accomplished by using a three-electrode system including working electrode (WE), counter electrode (CE) and reference electrode (RE). In this work, our system consists of gold (Au) We, platinum (PT) CE and silver/silver chloride (Ag/AgCl) RE. The potential relative to the reference electrode is forward- and reverse-scanned at the working electrode while the current flows through the counter electrode is observed in a solution. In this study, we investigate systematically the redox potential of the different analytes under various conditions in concentration and pH. Therefore, this study can be referenced for studies in exploring a variety range of biological samples, cells, tissues, lipids, and proteins on surfaces

Warped Brane worlds in Critical Gravity

We investigate the brane models in arbitrary dimensional critical gravity presented in [Phys. Rev. Lett. 106, 181302 (2011)]. For the model of the thin branes with codimension one, the Gibbons-Hawking surface term and the junction conditions are derived, with which the analytical solutions for the flat, AdS, and dS branes are obtained at the critical point of the critical gravity. It is found that all these branes are embedded in an AdS$_{n}$ spacetime, but, in general, the effective cosmological constant $\Lambda$ of the AdS$_{n}$ spacetime is not equal to the naked one $\Lambda_0$ in the critical gravity, which can be positive, zero, and negative. Another interesting result is that the brane tension can also be positive, zero, or negative, depending on the symmetry of the thin brane and the values of the parameters of the theory, which is very different from the case in general relativity. It is shown that the mass hierarchy problem can be solved in the braneworld model in the higher-derivative critical gravity. We also study the thick brane model and find analytical and numerical solutions of the flat, AdS, and dS branes. It is find that some branes will have inner structure when some parameters of the theory are larger than their critical values, which may result in resonant KK modes for some bulk matter fields. The flat branes with positive energy density and AdS branes with negative energy density are embedded in an $n$-dimensional AdS spacetime, while the dS branes with positive energy density are embedded in an $n$-dimensional Minkowski one.Comment: 14 pages, 7 figures, updated version, accepted by EPJ

A Note on Symplectic, Multisymplectic Scheme in Finite Element Method

We find that with uniform mesh, the numerical schemes derived from finite element method can keep a preserved symplectic structure in one-dimensional case and a preserved multisymplectic structure in two-dimentional case in certain discrete version respectively. These results are in fact the intrinsic reason that the numerical experiments indicate that such finite element algorithms are accurate in practice.Comment: 7 pages, 3 figure

General stationary charged black holes as charged particle accelerators

We study the possibility of getting infinite energy in the center of mass frame of colliding charged particles in a general stationary charged black hole. For black holes with two-fold degenerate horizon, it is found that arbitrary high center-of-mass energy can be attained, provided that one of the particle has critical angular momentum or critical charge, and the remained parameters of particles and black holes satisfy certain restriction. For black holes with multiple-fold degenerate event horizons, the restriction is released. For non-degenerate black holes, the ultra-high center-of-mass is possible to be reached by invoking the multiple scattering mechanism. We obtain a condition for the existence of innermost stable circular orbit with critical angular momentum or charge on any-fold degenerate horizons, which is essential to get ultra-high center-of-mass energy without fine-tuning problem. We also discuss the proper time spending by the particle to reach the horizon and the duality between frame dragging effect and electromagnetic interaction. Some of these general results are applied to braneworld small black holes.Comment: 23 pages, no figures, revised version accepted for publication in Phys. Rev.