Influence of Discretization Step on Asymptotic Stability of a Certain Class of Two-dimensional Continuous-discrete Fractional Linear Systems

The effectiveness of this paper lies in the influence of the discretization step on the asymptotic stability of the positive two-dimensional fractional linear systems. It aims at investigating whether, how and when this step affects the asymptotically stable two-dimensional positive fractional linear continuous-discrete systems. To accomplish this study, a new test was outlined and used so that the asymptotic stability of the system was measured both before and after being exposed to the samplin...     

Minimality of invariant submanifolds in metric contact pair geometry

Annali di Matematica Pura ed Applicata (1923 -) - We study invariant submanifolds of manifolds endowed with a normal or complex metric contact pair with decomposable structure tensor $$\phi $$ ....     

Synthesis of heterocyclic nitrogen derivatives from aryl‐1,4‐benzoquinones

Treatment of 2‐aryl‐3,6‐bis(arylamino)‐1,4‐benzoquinones 2a‐h with different acid chlorides, namely acetyl, phenylacetyl and chloroacetyl chloride yields 3a,7a‐dihydropyrrolo[2,3‐f]indole‐2,6‐dione 3, 5‐(N‐phenylacetylarylamino)‐3‐phenylindole‐2,6‐dione 4 and 3‐chloro‐5‐(N‐chloroacetylarylamino)indole‐2,6‐dione 5 respectively. Stirring 2‐aryl‐1,4‐benzoquinones ( 1 ) with ethylenediamine and/or o‐phenyl‐enediamine in methylene chloride gives pyrazino[2,3‐g]quinoxalines derivative 6 and/or tetrapentacene derivative 7 respectively. The products 5‐aryl‐ and 6‐aryl‐1/H‐indazole‐4,7‐diones 8 and 9 were obtained in the 1,3‐dipolar cycloaddition of diazomethane to ( 1 ).     

Uranium micelle-mediated extraction in acetate medium: factorial design optimization

A micelle-mediated extraction (CPE) procedure has been developed to remove trace amounts of uranium from wastewater using a non-ionic surfactant (Triton (X-100)) and lipophilic chelating extracting agent (D2EHPA) in acetate medium. The methodology used is based on the formation of metal complexes soluble in a micellar phase of a non-ionic surfactant. The uranyl ions complexes are then extracted into the surfactant-rich phase at a ambient temperature. The effects of different operating parameters such as the concentrations of Triton (X-100), D2EHPA and metal ions, temperature, sodium acetate rate and pH on the cloud point extraction of uranyl ions were studied in details and a set of optimum conditions were obtained. The results showed, without contribution of energy (ambient temperature), that up to 1000?ppm of uranyl ions can quantitatively be removed (>97?%) in a single CPE extraction using optimum conditions.     

Lower bounds on fluctuations for internal DLA

We consider internal diffusion limited aggregation in dimension two or more. This is a random cluster growth model, where random walks start at the origin of the lattice, one at a time, and stop moving when reaching a site that is not occupied by previous walks. When $n$ random walks are sent from the origin, we establish a lower bound for the inner and outer errors fluctuations of order square root of the logarithm of $n$ . When dimension is three or more, this lower bound matches the upper bound recently obtained in independent works of Asselah and Gaudillière (Ann Prob arXiv:1011.4592, 2010) and Jerison et al. (Internal DLA and the Gaussian free field arXiv:1012.3453, 2010). Also, we produce as a corollary of our proof of Asselah and Gaudillière (Ann Prob arXiv:1011.4592, 2010), an upper bound for the fluctuation of the inner error in a specified direction.     

Positive Solutions of Nonlinear Elliptic Problem in a Non-Smooth Planar Domain

We find and prove 3G inequalities for the Laplacian Green function with the Dirichlet boundary condition, which are applied to show the existence of positive continuous solutions of the nonlinear equation Δu-Vu=g（·,u）, where V and g are Borel measurable functions, required to satisfy suitable assumptions related to a new functional class J. Our approach uses the Schauder fixed point theorem.     

Surface chemistry effects on the performance of an electrochemical DNA sensor

E-DNA sensors are a reagentless, electrochemical oligonucleotide sensing platform based on a redox-tag modified, electrode-bound probe DNA. Because E-DNA signaling is linked to hybridization-linked changes in the dynamics of this probe, sensor performance is likely dependent on the nature of the self-assembled monolayer coating the electrode. We have investigated this question by characterizing the gain, specificity, response time and shelf-life of E-DNA sensors fabricated using a range of co-adsorbates, including both charged and neutral alkane thiols. We find that, among the thiols tested, the positively charged cysteamine gives rise to the largest and most rapid response to target and leads to significantly improved storage stability. The best mismatch specificity, however, is achieved with mercaptoethanesulfonic and mercaptoundecanol, presumably due to the destabilizing effects of, respectively, the negative charge and steric bulk of these co-adsorbates. These results demonstrate that a careful choice of co-adsorbate chemistry can lead to significant improvements in the performance of this broad class of electrochemical DNA sensors.     

Stripping voltammetric determination of mercury(II) and lead(II) using screen-printed electrodes modified with gold films, and metal ion preconcentration with thiol-modified magnetic particles

A novel approach to the electrochemical determination of heavy metals in tap water using anodic stripping voltammetry was developed using screen-printed electrodes modified with gold films. After optimisation of the experimental conditions, the screen-printed electrodes modified with gold films displayed excellent linear behaviour in the examined concentration range from 2 to 16 µg L^-1 mercury and lead in 50 mM HCl with a detection limit of 1.5 µg L^-1 and 0.5 µg L^-1 for mercury and lead, respectively. In order to decrease the working range down to less than 1 µg L^-1, a preconcentration step based on the use of magnetic particles modified with thiols was introduced into the protocol. Applying optimum binding conditions, the assay using screen-printed electrodes modified with gold films displayed excellent linear behaviour in the concentration range 0.1 to 0.8 µg L^-1 in 50 mM HCl. The detection limit after a 120 s deposition time for mercury and lead were 0.08 µg L^-1 and 0.02 µg L^-1, respectively. The method has been applied to the determination of mercury and lead traces in tap water