The Revival Wave Induced Spontaneously in a BZ-Type Mixture

We have examined the unusual behavior of wave propagation in the BrO₃ ^- - 1,4- cyclohexanedione - ferroin reaction system. Two patterns of traveling wave have been induced spontaneously with long time lag in the reaction process. A new wave has been induced as a concentric pattern after an initially induced wave has disappeared. The initially induced wave shows an irregular spiral pattern with a high wave frequency. The two waves show very different behavior in the pattern and in other wave characteristics as well. We compared the behavior of the two waves and suggested an appropriate reaction process for unusual behavior of wave propagation in the system by considering the reaction intermediates of the organic compounds. This revised version was published online in June 2006 with corrections to the Cover Date.     

Fuzzy polynomial regression analysis using shape preserving operation

In this paper, we describe a method for fuzzy polynomial regression analysis for fuzzy input-output data using shape preserving operations based on Tanaka’s approach. Shape preserving operations simplifies the computation of fuzzy arithmetic operations. We derive the solution using general linear program.     

Effect of Water Hardness on Catechin and Caffeine Content in Green Tea Infusions

The health benefits of green tea are associated with its high catechin content. In scientific studies, green tea is often prepared with deionized water. However, casual consumers will simply use their local tap water, which differs in alkalinity and mineral content depending on the region. To assess the effect of water hardness on catechin and caffeine content, green tea infusions were prepared with synthetic freshwater in five different hardness levels, a sodium bicarbonate solution, a mineral salt solution, and deionized water. HPLC analysis was performed with a superficially porous pentafluorophenyl column. As water hardness increased, total catechin yield decreased. This was mostly due to the autoxidation of epigallocatechin (EGC) and epigallocatechin gallate (EGCG). Epicatechin (EC), epicatechin gallate (ECG), and caffeine showed greater chemical stability. Autoxidation was promoted by alkaline conditions and resulted in the browning of the green tea infusions. High levels of alkaline sodium bicarbonate found in hard water can render some tap waters unsuitable for green tea preparation.     

Adsorption of argon from sub- to supercritical conditions on graphitized thermal carbon black and in graphitic slit pores: a grand canonical Monte Carlo simulation study

In this paper we consider the adsorption of argon on the surface of graphitized thermal carbon black and in slit pores at temperatures ranging from subcritical to supercritical conditions by the method of grand canonical Monte Carlo simulation. Attention is paid to the variation of the adsorbed density when the temperature crosses the critical point. The behavior of the adsorbed density versus pressure (bulk density) shows interesting behavior at temperatures in the vicinity of and those above the critical point and also at extremely high pressures. Isotherms at temperatures greater than the critical temperature exhibit a clear maximum, and near the critical temperature this maximum is a very sharp spike. Under the supercritical conditions and very high pressure the excess of adsorbed density decreases towards zero value for a graphite surface, while for slit pores negative excess density is possible at extremely high pressures. For imperfect pores (defined as pores that cannot accommodate an integral number of parallel layers under moderate conditions) the pressure at which the excess pore density becomes negative is less than that for perfect pores, and this is due to the packing effect in those imperfect pores. However, at extremely high pressure molecules can be packed in parallel layers once chemical potential is great enough to overcome the repulsions among adsorbed molecules.     

Esters of 2-iodoxybenzoic acid: hypervalent iodine oxidizing reagents with a pseudobenziodoxole structure

Esters of 2-iodoxybenzoic acid (IBX-esters) were prepared by the hypochlorite oxidation of the corresponding 2-iodobenzoate esters and isolated as chemically stable, microcrystalline products. These hypervalent iodine compounds are potentially valuable oxidizing reagents belonging to a new class of pentavalent iodine compounds with a pseudobenziodoxole structure. Methyl 2-iodoxybenzoate can be further converted to the diacetate or a bis(trifluoroacetate) derivative by treatment with acetic anhydride or trifluoroacetic anhydride, respectively. Single-crystal X-ray diffraction analysis of methyl 2-[(diacetoxy)iodosyl]benzoate 8a reveals a pseudobenziodoxole structure with three relatively weak intramolecular I...O interactions. The dimethyl and diisopropyl esters of 2-iodoxyisophthalic acid were prepared by oxidation of the respective iodoarenes with dimethyldioxirane. Single-crystal X-ray diffraction analysis of diisopropyl 2-iodoxyisophthalate 6b showed intramolecular I...O interaction with the carbonyl oxygen of only one of the two carboxylic groups, while NMR spectra in solution indicated equivalency of both ester groups. IBX-esters, methyl 2-[(diacetoxy)iodosyl]benzoate, and 2-iodoxyisophthalate esters can oxidize alcohols to the respective aldehydes or ketones in the presence of trifluoroacetic acid or boron trifluoride etherate. The bis(trifluoroacetate) derivative can oxidize alcohols to carbonyl compounds without acid catalyst.     

Recent Electrokinetic and Microfluidic Strategies for Detection of Amyloid Beta Peptide Biomarkers: Towards Molecular Diagnosis of Alzheimer's Disease

Among all neurodegenerative diseases, Alzheimer's Disease (AD) is the most prevalent worldwide, with a huge burden to the society and no efficient AD treatment so far. Continued efforts have been being made towards early and powerful diagnosis of AD, in the hope for a successful set of clinical trials and subsequently AD curative treatment. Towards this aim, detection and quantification of amyloid beta (Aβ) peptides in cerebrospinal fluid (CSF) and other biofluids, which are established and validated biomarkers for AD, have drawn attention of the scientific community and industry over almost two decades. In this work, an overview on our major contributions over 15 years to develop different electrokinetic and microfluidic strategies for Aβ peptides detection and quantification is reported. Accordingly, discussions and viewpoints on instrumental and methodological developments for microscale electrophoresis, microfluidic designs and immuno‐enrichment / assays on magnetic beads in microchannels for tracing Aβ peptides in CSF are given in this review.     

Development of the diffusive gradient in thin films technique for the measurement of labile mercury species in waters

The diffusive gradients in thin films (DGT) technique, utilizing resin gel with ion-exchange resin Duolite GT73 and new ion-exchange resin Ambersep GT74, was investigated for the accumulation of four mercury species (Hg²⁺, CH₃Hg⁺, C₂H₅Hg⁺, C₆H₅Hg⁺). The diffusion coefficients of mercury species in agarose gel calculated on the basis of Fick’s Law were mercury species-specific. The diffusion coefficients of Hg²⁺ and CH₃Hg⁺ at 25 °C (9.07 ± 0.23 × 10⁻⁶ cm² s⁻¹ and 9.06 ± 0.30 × 10⁻⁶ cm² s⁻¹, respectively) were very similar, but the diffusion coefficients of C₂H₅Hg⁺ (6.87 ± 0.23 × 10⁻⁶ cm² s⁻¹) and C₆H₅Hg⁺ (3.86 ± 0.19 × 10⁻⁶ cm² s⁻¹) were significantly lower. Influence of experimental conditions (pH, selected cations, chlorides and humic substance) on mercury species accumulation by DGT was studied. The DGT technique was applied to river water spiked with mercury species.     

Advanced nanostructure Ti0.7In0.3O2 support enhances electron transfer to Pt: Used as high performance catalyst for oxygen reduction reaction

ABSTRACT

The slow rate of the oxygen reduction reaction (ORR) and the instability of Pt based catalysts are two of the most important issues which must be solved in order to make proton exchange membrane fuel cells (PEMFCs) a reality. Here, we present a new approach by exploring robust non-carbon Ti_0.7In_0.3O₂ used as a novel functionalised co-catalytic support for Pt. This approach is based on the novel nanostructure Ti_0.7In_0.3O₂ support with “electronic transfer mechanism” from Ti_0.7In_0.3O₂ to Pt that can modify surface electronic structure of Pt, owing to a shift in the d-band centre of the surface Pt atoms. The 20 wt% Pt/Ti_0.7In_0.3O₂ catalyst shows high activity than that of that of the commercial 20 wt% Pt/C (E-TEK). Our data suggest this enhancement is a result of both the electronic structure change of Pt upon its synergistic interaction with Ti_0.7In_0.3O₂ and the inherent structural and chemical stability and the corrosion-resistance of the Ti_0.7In_0.3O₂ in acidic and oxidative environments.     

The Resurgence of the Highly Ylidic N‐Heterocyclic Olefins as a New Class of Organocatalysts

In recent decades, N‐heterocyclic carbenes have become established as a prevalent family of organocatalysts. N‐Heterocyclic olefins, the alkylidene derivatives of N‐heterocyclic carbenes, have recently also emerged as efficient promoters for CO₂ fixation and polymerization reactions. Their extraordinarily strong Lewis/Brønsted basicity suggests great potential as a new class of organocatalysts for a broad range of reactions in synthetic chemistry.