Active sliding observer scheme based fractional chaos synchronization

In this paper, a novel observer scheme is proposed for synchronization of fractional order chaotic systems. Our approach employs a combination of a classical sliding observer and an active observer, where the active observer serves to increase the attraction strength of sliding surface. Using the theory of Lyapunov function, synchronization of the fractional order response with the fractional order drive system is achieved in both ideal and mismatched cases. By merit of fractional order differentiation and integration, i.e. differintegration formula, it is proved that state synchronization is established in a finite time. Numerical simulations are presented to verify the effectiveness of the proposed observer.     

Magnetic properties of NdAu2Ge2

Physical properties of NdAu₂Ge₂, crystallising with the tetragonal ThCr₂Si₂-type crystal structure, were investigated by means of magnetic, calorimetric and electrical transport measurements as well as by neutron diffraction. The compound exhibits antiferromagnetic ordering below T_N=4.5 K with a collinear magnetic structure of the AFI-type. The neodymium magnetic moments are parallel to the c-axis and amount to 1.04(4) μ_B at 1.5 K. The observed magnetic behaviour is strongly influenced by crystalline electric field effect.     

Formation, characterization, and chemistry of undecanoic acid-terminated silicon surfaces: patterning and immobilization of DNA

This paper describes a simple strategy for DNA immobilization on chemically modified and patterned silicon surfaces. The photochemical modification of hydrogen-terminated Si(111) with undecylenic acid leads to the formation of an organic monolayer covalently attached to the surface through Si-C bonds without detectable reaction of the carboxylic acid group, providing indirect support of a free radical mechanism. Chemical activation of the acid function was achieved by a simple chemical route using N-hydroxysuccinimide (NHS) in the presence of N-ethyl-N'-(3-dimethylaminopropyl) carbodiimide hydrochloride. Single strand DNA with a 5'-dodecylamine group was then coupled to the NHS-activated surface by amide bond formation. Using a previously reported chemical patterning approach, we have shown that DNA can be immobilized on silicon surfaces in spatially well-resolved domains. Methoxytetraethyleneglycolamine was used to inhibit nonspecific adsorption. The resulting DNA-modified surfaces have shown good specificity and chemical and thermal stability under hybridization conditions. The sequential reactions on the surface were monitored by ATR-FTIR, X-ray Photoelectron Spectroscopy, and fluorescence spectroscopy.     

A simple approach to micropatterning and surface modification of poly(dimethylsiloxane)

Ozone treatment is an efficient economical, alternative method for surface activation of poly(dimethylsiloxane) (PDMS). This is illustrated by the derivatization of a PDMS surface with (3-aminopropyl)triethoxysilane (APTES). The apparent surface concentration of amino groups was found to be ca. 10(-8) mol/cm2 using UV/visible spectroscopy of the product from the reaction of the amino groups and fluorescamine. Potential application for micropatterning of biologically active interfaces was demonstrated by the covalent immobilization of oligonucleotides. A simple process for photolithographic patterning on PDMS surfaces has been developed.     

Excess volumes of the binary mixtures 1,2-dichloroethane ? n -alkanols [C2?C6]

Volume changes on mixing of binary systems formed by 1,2-dichloroethane andn-alcohols, namely, ethanol,n-propanol,n-butanol,n-pentanol andn-hexanol were measured as a function of composition at 30, 35, 40 and 45 °C. At all compositions theV ^E values are all positive for all systems. The molar excess volumes of mixing for equimolar mixtures increase as the length of carbon chain increases.V ^E becomes more positive on increasing temperature. The positive value of the excess volume has been attributed to breaking of hydrogen bonds of associated species of alcohol by dilution with 1,2-dichloroethane.     

Delamination of surfactant-intercalated brucite-like hydroxy salts of cobalt and copper and solvothermal decomposition of the resultant colloidal dispersions

Surfactant anion intercalated hydroxy salts of copper and cobalt of the formula M(OH)2- x (surf)x.mH2O [M = Cu, Co; surf = dodecyl sulfate, dodecyl benzene sulfonate, and x = 0.5 for Cu and 0.67 for Co] delaminate readily in 1-butanol to give translucent colloidal dispersions that are stable for months. The extent of delamination and the colloidal dispersion observed in these solids is higher than what had been observed for layered double hydroxides. The dispersions yield the corresponding nanoparticulate oxides on solvothermal decomposition. While the copper hydroxy salt forms approximately 300 nm dendrimer-like CuO nanostructures comprising nanorods of approximately 10 nm diameter, the cobalt analogue forms approximately 20 nm superparamagnetic particles of Co3O4.     

Mobility of O+ in He and interaction potential of HeO+

New experimental measurements are reported for the mobility of O(+) ions in He gas at 300 K. The accuracy of these new values is estimated as +/-2.5%, which allows them to serve as a stringent test of a new ab initio potential that we have calculated using the RCCSD(T) method. We employed the aug-cc-pV5Z basis set with counterpoise corrections and took spin-orbit coupling into account. The present experimental values lie below the calculated ones, but the difference becomes statistically significant only at moderate and high values of the ratio of the electric field strength to the gas number density; even there they are only marginally significant.     

Diastereoselective synthesis of chloro‐ and fluoro‐aniline containing phosphonate esters in a three‐component condensation

New phosphonate ester derivatives were obtained by in situ stereo‐specific reaction between triphenyl phosphite and dialkyl acetylenedicarboxylates in the presence of a series of halogenated anilines. Spectroscopic data and X‐ray crystallography analysis are in agreement with the gauche arrangement for the two vicinal protons in the structures. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:222–227, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20600     

A Highly Sensitive and Selective Multiwall Carbon Nanotubes/Nafion/Au Microarrays Electrode for Dopamine Determination

This work presents the fabrication of Nafion (Nf) or Nafion/Multiwalled Carbon Nanotubes (Nf/MWCNTs) modified gold microarray (Au‐µA) and macro‐(Au‐M)electrode biosensors. The surface morphologies of the above electrodes were examined using SEM. The catalytic properties of the above electrodes towards dopamine were tested using square wave voltammetric technique. The Nf/MWCNT/Au‐µA electrode exhibited a wide range (0.1–1000 nM) of linearity among the other electrodes. The LOD of Nf/MWCNT/Au‐µA electrode was 50 pM for dopamine in the presence of 5000 µM ascorbic acid. Therefore, the Nf/MWCNT/Au‐µA biosensor was applied for the determination of dopamine in human serum.