Photorefractive polymeric optical spatial solitons

We predict the formation of optical spatial solitons in photorefractive polymers. The orientational enhancement from the doped chromophores and the dependency of the quantum efficiency of generating mobile holes on the electric field make the polymeric solitons behave differently from other photorefractive solitons.     

Glycolipids from the formosan soft coral Lobophytum crassum

Three glycolipids (1--3), possessing a sugar moiety at C-2 of glycerol ether, have been isolated from the Formosan soft coral Lobophytum crassum. Their structures were elucidated by spectroscopic methods, particularly in 1D- and 2D-NMR experiments. The absolute configurations on the sugar portion and lipid aglycon of 1--3 were determined by methanolysis, chemical transformation and the application of Mosher's method on 1 and 3. Compounds 1--3 exhibited weak cytotoxic activities.     

Neolemnane-type sesquiterpenoids from a formosan soft coral Paralemnalia thyrsoides

Six new sesquiterpenoids, paralemnolins D-I (1-6), have been isolated from the EtOAc extract of the soft coral Paralemnalia thyrsoides. The structures of these metabolites were determined by extensive spectroscopic analysis and by comparison of their spectral data with those of related metabolites. The absolute stereochemistry of these metabolites was established by application of the Mosher's method on 1 and on the basis of the absolute structures of other related compounds previously isolated from the soft corals of the genera Paralemnalia and Lemnalia. Cytotoxicity of these metabolites toward a limited panel of cancer cell lines also is reported.     

Reactivity and mechanism of stable heterocyclic silylenes with carbon tetrachloride

The potential energy surfaces for the reactions of stable silylenes with carbon tetrachloride have been characterized in detail using density functional theory [B3LYP/6-311G(d)], including zero-point corrections. Five stable silylene species (1-5) have been chosen in this work as model reactants. The activation barriers and enthalpies of the reactions are compared to determine the relative reactivity of the stable silylenes on the reaction potential energy surface. Our theoretical findings suggest that stable silylene 5, which has two carbon atoms bonded to the silicon center and does not contain a resonance structure, is relatively unstable with respect to the reaction with haloalkanes, in comparison with the other stable silylenes (1-4). Of the three possible reaction paths, Cl abstraction (path 1), CCl3 abstraction (path 2), and CCl4 insertion (path 3), path 1 is found to be most favorable, with a very low activation energy and a large exothermicity. In short, electronic as well as steric factors play a dominant role in determining the chemical reactivity of the stable silylene species kinetically as well as thermodynamically. Furthermore, a configuration mixing model based on the work of Pross and Shaik is used to rationalize the computational results. The results obtained allow a number of predictions to be made.     

Development of a titanium dioxide nanoparticle pipette-tip for the selective enrichment of phosphorylated peptides

The selective enrichment of specific proteins or peptides on micropipette tips prior to mass spectrometry analysis, which can minimize non-specific interferences as well as sample loss, has been an important issue in current proteomics field. In this paper, we have developed an easy-to-use phosphopeptide-selective pipette tip in which titanium dioxide nanoparticles were embedded in monolithic structure photopolymerized from ethylene glycol dimethacrylate. The simple and convenient fabrication was feasible in a commercial polypropylene pipette tip. Phosphorylated peptides were isolated from non-phosphopeptides by TiO(2) nanoparticle and eluted by 100 mM ammonium phosphate (pH 8.5), which was compatible with 2,5-dihydroxybenzoic acid (DHB)/1% phosphoric acid matrix and allowed for direct analysis of the elution fraction by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) without the necessity of desalting pretreatment. Tryptic digested alpha-casein and beta-casein spiked into bovine serum albumin (BSA) nonphosphorylated peptides (molar ratio 1:1:10) were used to assess the selectivity of TiO(2) tips. The effect of 50 mM ammonium hydrogencarbonate, pH 8 in 50% acetonitrile used as a wash buffer in reduction of nonspecific bound peptide to TiO(2) tip was dramatic. Almost all non-phosphopeptides were not detected by MALDI-MS analysis. The lowest detectable amount of phosphopeptide was estimated at low femtomole level. The easy-to-use TiO(2)-embeded tips operated in combination with the modified wash and elution conditions enable an efficient phosphopeptide enrichment for mass spectrometric analysis.     

Alliance or no alliance—Bargaining power in competing reverse supply chains

This work investigates how bargaining power affects negotiations between manufacturers and reverse logistics providers in reverse supply chains under government intervention using a novel three-stage reverse supply chain model for two scenarios, a reverse logistics provider alliance and no reverse logistics provider alliance. Utilizing the asymmetric Nash bargaining game, this work seeks equilibrium negotiation solutions. Analytical results indicate that the reverse logistics provider alliance increases the bargaining power of reverse logistics providers when negotiating with a manufacturer for a profitable recycled-component supply contract; however, manufacturer profits are often reduced. Particularly in the case of an recycled-component vender-dominated market, a reverse logistics alliance with extreme bargaining power may cause a counter-profit effect that results in the decreases of profits for all players involved, including buyers (i.e., manufacturers) and allied recycled-component venders (i.e., reverse logistics providers). Additional managerial insights are provided for discussion.     

Optimal age-replacement time with minimal repair based on cumulative repair-cost limit for a system subject to shocks

An operating system is subject to random shocks that arrive according to a non-homogeneous Poisson process and cause the system failed. System failures experience to be divided into two categories: a type-I failure (minor), rectified by a minimal repair; or a type-II failure (catastrophic) that calls for a replacement. An age-replacement model is studied by considering both a cumulative repair-cost limit and a system’s entire repair-cost history. Under such a policy, the system is replaced at age T, or at the k-th type-I failure at which the accumulated repair cost exceeds the pre-determined limit, or at any type-II failure, whichever occurs first. The object of this article is to study analytically the minimum-cost replacement policy for showing its existence, uniqueness, and the structural properties. The proposed model provides a general framework for analyzing the maintenance policies, and presents several numerical examples for illustration purposes.     

A speech encryption using fractional chaotic systems

In this paper, a new speech encryption using fractional chaotic systems is presented. A two-channel transmission method is used where the original speech is encoded using a nonlinear function of the chaotic states. Conditions for synchronization between fractional chaotic systems through one variable have been investigated theoretically by using the Laplace transform. The keys, key space, key selection rules, and sensitivity to keys are discussed in detail. Results show that the original speech is well masked in the ciphertexts yet recovered faithfully and efficiently by the present schemes.     

Technology behind commercial devices for blood glucose monitoring in diabetes management: a review

The blood glucose monitoring devices (BGMDs) are an integral part of diabetes management now-a-days. They have evolved tremendously within the last four decades in terms of miniaturization, rapid response, greater specificity, simplicity, minute sample requirement, painless sample uptake, sophisticated software and data management. This article aims to review the developments in the technologies behind commercial BGMD, especially those in the areas of chemistries, mediators and other components. The technology concerns, on-going developments and future trends in blood glucose monitoring (BGM) are also discussed.     

Sodium ion ordering and vacancy cluster formation in NaxCoO2 (x=0.71 and 0.84) single crystals by synchrotron X-Ray diffraction

In the rich phase diagram of NaxCoO2, x=0.71 enjoys special stability and is called the Curie-Weiss metal due to its anomalous properties. Similarly, x=0.84 prepared from high temperature melt is a special end point beyond which the system phase separates. Using synchrotron x-ray diffraction on single crystals, we discovered sqrt[12]a and sqrt[13]a superlattice structures which we interpret as the ordering of Na (vacancy) clusters. These results lead to a picture of coexisting local moments and itinerant carriers and form the first step towards understanding the many anomalous properties of cobaltates.