A digital pseudo-random number generator based on sawtooth chaotic map with a guaranteed enhanced period

Nonlinear Dynamics - We investigate tunneling behavior between two bright solitons in a Bose–Einstein condensate with attractive contact interactions between atoms. The explicit tunneling...     

Refolding of detergent‐denatured lysozyme using β‐cyclodextrin‐assisted ion exchange chromatography

Chromatography‐based protein refolding is widely used. Detergent is increasingly used for protein solubilization from inclusion bodies. Therefore, it is necessary to develop a refolding method for detergent‐denatured/solubilized proteins based on liquid chromatography. In the present work, sarkosyl‐denatured/dithiothreitol‐reduced lysozyme was used as a model, and a refolding method based on ion exchange chromatography, assisted by β‐cyclodextrin, was developed for refolding detergent‐denatured proteins. Many factors affecting the refolding, such as concentration of urea, concentration of β‐cyclodextrin, pH and flow rate of mobile phases, were investigated to optimize the refolding conditions for sarkosyl‐denatured lysozymes. The results showed that the sarkosyl‐denatured lysozyme could be successfully refolded using β‐cyclodextrin‐assisted ion exchange chromatography. Copyright © 2012 John Wiley & Sons, Ltd.     

Direct electrochemistry of glucose oxidase immobilized on porous carbon nanofiber/room temperature ionic liquid/chitosan composite film and its biosensing application

The direct electron transfer of glucose oxidase (GOD) immobilized on a composite matrix based on porous carbon nanofibers (PCNFs), room-temperature ionic liquid (RTIL), and chitosan (CHIT) underlying on a glassy carbon electrode was achieved. The combination of the PCNFs, RTIL, and CHIT provided a suitable microenvironment for GOD to transfer electron directly. In deaerated buffer solutions (pH 7.0), the cyclic voltammetry of the GOD/PCNFs/RTIL/CHIT composite films showed a pair of well-defined redox peaks with the formal potential of −0.45 V (vs. SCE). The synergistic effort of the PCNFs, RTIL, and CHIT also promoted the stability of GOD in the composite film and retained its bioactivity.     

Enhanced Sensitive Electrochemical Sensor for Simultaneous Catechol and Hydroquinone Detection by Using Ultrasmall Ternary Pt-based Nanomaterial

The simple and effective method for the novel synthesis of Pt-based nanoparticle was presented with high efficiency. The sensitive catalyst for the simultaneous detection of catechol and hydroquinone was prepared by depositing ternary metal complex on fluorine-doped tin-oxide (FTO). The composition and morphology of nanomaterials were characterized by TEM, HRTEM, XRD, XPS, and EDS (energy dispersive spectroscopy). The size of the Pt-based nanomaterial was about 5±1 nm. The electrochemical performance of the modified catalyst was studied by CV, DPV, and EIS. The modified PtNiCu@FTO catalyst possessed good electro-oxidation activity for hydroquinone and catechol and used for simultaneous detection of catechol and hydroquinone at scan rate of 20 mV s⁻¹ (vs. Ag/AgCl). Detection responses were found in the ranges of 5–2900 μM for hydroquinone and 5–3000 μM for catechol. The detection limits (LOD) for HQ and CC were observed as 0.35 and 0.29 μM, respectively. The sensitivity of HQ and CC were 1515.55 and 1485 μA mM⁻¹ cm⁻², respectively. The prepared nanomaterial were effectively applied for the determination of CC and HQ in real samples.     

On the role of nonlinearities in the Boussinesq-type wave equations

Longitudinal mechanical waves in biomembranes are described by a Boussinesq-type wave equation. It is shown that in this case the nonlinearities are of a different type compared with conventional models of solids. The governing equation analysed in this paper is the improved Heimburg–Jackson model with two dispersive terms. The soliton-type solutions of such a wave equation are found and analysed. The existence of solitons depends on the ratio of nonlinear terms and the width of solitons is governed by dispersive terms.     

Synthesis and toxicity assay of ceramic nanophosphors for bioimaging with near-infrared excitation

Yttrium hydroxyl carbonate (Y(OH)CO₃) precursors were synthesized by the homogeneous co-precipitation method in the presence of polyacrylic acid (PAAc). Resultant precursor particle size is about 15–20 nm with narrow size distribution whereas the particle size is smaller than those acquired by the conventional homogeneous precipitation method. Effective decrease of Y(OH)CO₃ particle size was found to be higher for the presence of weak polyanionic ionomer such as PAAc than the presence of strong polyanionic ionomer such as sodium polystyrene sulfonate (PSS). It was observed that the morphology and size of the precursors are almost unchanged after the calcination process. Er³⁺ doped Y₂O₃ nanoparticles were synthesized by PAAc assisted homogeneous co-precipitation method showed bright green (550 nm) and red (660 nm) upconversion (UC) as well as near-infrared (NIR) fluorescence (1550 nm) under 980-nm excitation. UC and NIR fluorescence bioimaging and in-vitro cytotoxicity assay of Er³⁺ doped Y₂O₃ nanoparticles were successfully attempted with commercially available macrophages and B-cell hybridomas. Cellular uptake of nanoparticles is evidenced from bright field, UC and NIR fluorescence images of macrophages.     

Triple condensation of aryl methyl ketones catalyzed by amine and trifluoroacetic acid: straightforward access to 1,3,5-triarylbenzenes under mild conditions

An efficient triple condensation reaction of aryl methyl ketones catalyzed by ethylenediamine and trifluoroacetic acid was reported. A broad scope of 1,3,5-triarylbenzenes was obtained in good to excellent yields. The reaction provides a novel and practical approach to access organic materials of polycyclic aromatic hydrocarbons under mild conditions.