Synthesis of glycerol-thiophene nanoparticles,a suitable sensing platform for voltammetric determination of guaifenesin

Boronic acid functionalized materials have gained much attention in both chemistry and biology fields due to their multivalent covalent interactions with cis-diol containing (macro) molecules. The remarkable progress in this field has resulted in the development of their biomedical applications, such as, biosensors and nanocarriers. In this study, the spherical nanoparticles consisting of glycerol and 2,5-thiophenediylbisboronic acid were synthesized by one-pot ring opening copolymerization of a mixture of glycidol and 2,5-thiophenediylbisboronic acid. The synthesized nanoparticles were used for the modification of the glassy carbon electrode and the determination of Guaifenesin. The synthesized polymeric nanoparticles were characterized by different spectroscopic and microscopic methods including UV–vis, IR, NMR, DLS, and SEM. Additionally, the electrochemical behavior of the fabricated electrode toward Guaifenesin was investigated with cyclic voltammetry and electrochemical impedance spectroscopy.     

One-Pot Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones and Their Sulfur Derivatives with H2SO4 Supported on Silica Gel or Alumina

The one-pot condensation of aromatic aldehydes, β-dicarbonyl compounds, and urea or thiourea in the presence of H₂SO₄ supported on silica gel or alumina (80% m/m) in refluxing n-hexane produces 3,4-dihydropyrimidin-2(1H)-ones and their sulfur derivatives in high to excellent yields.     

Novel toughened automotive clearcoats modified by a polyester‐amide hyperbranched polymer: structural and mechanical aspects

The present work attempts to study the mechanical properties and toughness behavior of a typical acrylic melamine clearcoat modified by a polyester‐amide hyperbranched polymer (HBP). Formulations were such that 0, 5, 10, 25 and 50% (molar percent) of total acrylic hydroxyl groups were stoichiometrically substituted by those of HBP. Bulk and surface of the clearcoats were studied by various mechanical techniques including hardness, tensile, dynamic mechanical thermal analysis (DMTA), nano‐indentation and scratch tests. In addition a scanning electron microscope (SEM) was utilized to observe the morphology of the fractured films. The bulk mechanical properties showed that a low loading (5 molar %) of HBP was sufficient to considerably increase the bulk hardness, cross‐linking density and toughness. DMTA and SEM results proved the occurrence of a single‐phase blend and that the shear deformation was the main toughening mechanism of HBP modified clearcoats. In general, it was revealed that the HBP not only could act as an excellent compatible toughening agent, but also maintained the clarity of the clearcoat and increased its scratch resistance. Copyright © 2013 John Wiley & Sons, Ltd.     

Corrosion behavior of low energy,high temperature nitrogen ion-implanted AISI 304 stainless steel

This work presents the results of a low-energy nitrogen ion implantation of AISI 304 type stainless steel (SS) at a moderate temperature of about 500°C. The nitrogen ions are extracted from a Kauffman-type ion source at an energy of 30 keV, and ion current density of 100 μA cm⁻². Nitrogen ion concentration of 6 × 10¹⁷, 8 × 10¹⁷ and 10¹⁸ ions cm⁻², were selected for our study. The X-ray diffraction results show the formation of CrN polycrystalline phase after nitrogen bombardment and a change of crystallinity due to the change in nitrogen ion concentration. The secondary ion mass spectrometry (SIMS) results show the formation of CrN phases too. Corrosion test has shown that corrosion resistance is enhanced by increasing nitrogen ion concentration.      

Highly sensitive carbon paste electrode with silver-filled carbon nanotubes as a sensing element for determination of free cyanide ion in aqueous solutions

We report on newly synthesized Ag(I)-filled multiwall carbon nanotubes as a potential sensing element in ion-selective carbon paste electrodes for the determination of free cyanide in aqueous solution. The electrode was obtained by entrapping the silver-filled nanotubes into a carbon paste and displays a Nernstian response with a slope of 59.8?±?0.3?mV decade^?1, a very wide linear range (from 21.0?nM to 0.1?M of cyanide), a lower detection limit of 13.0?nM, and a response time of <2?min. The operational lifetime is up to 3?months without significant deviation in normal function.

The phase transition to the quark-gluon plasma and its effect on hydrodynamic flow

It is shown that in ideal relativistic hydrodynamics a phase transition from hadron to quark and gluon degrees of freedom in the nuclear matter equation of state leads to a minimum in the excitation function of the transverse collective flow.     

Synthesis of boronic acid‐functionalized poly(glycerol‐oligoγ‐butyrolactone): Nano‐networks for efficient electrochemical sensing of biosystems

Despite the outstanding properties of hyperbranched polyglycerols such as biocompatibility and multifunctionality, enough attention has not been paid to the synthesis of their functional copolymers. This problem has limited the structural diversity of hyperbranched polyglycerols and hampers further developments and their practical usage. In this work, butyrolactone segments were incorporated into the backbone of polyglycerols by one‐pot ring‐opening copolymerization of a mixture of glycidol and γ‐butyrolactone in the presence of tin(II) 2‐ethylhexanoate. Poly(glycerol‐oligoγ‐butyrolactone)s were then crosslinked by 2,5‐thiophenediylbisboronic acid to obtain polymeric nanonetworks with 140 nm average size. Afterwards, the gold electrode was modified by the polymeric nano‐networks, and it was used for the determination of glucose, glycated hemoglobin, and Escherichia coli in phosphate buffer solution (pH = 9.0) through cyclic voltammetry and impedance spectroscopic. Taking advantage of the straightforward synthesis, cheap precursors and multifunctionality of poly(glycerol‐oligoγ‐butyrolactone)s, they could be used for real‐time sensing of a wide range of biosystems. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1430–1439     

Dye doped Eosin yellowish silica nanoparticles as novel fluorophore for a peroxyoxalate chemiluminescence system

In this work, we report the preparation and characterization of novel dye doped fluorophore Eosin yellowish silica nanoparticles (ESNPs). We synthesized ESNPs by the St?ber method via encapsulation of Eosin Yellowish in silica particles by the condensation of tetraethyl orthosilicate under alkaline condition at room temperature. The resulted ESNPs were characterized by transmission electron microscopy, atomic force microscopy; UV–Visible, fluorescence and Fourier transform infrared spectroscopy. The sizes of the nanoparticles have been found to be 300.0 (±1.0), 400.0 (±1.1) and 500.0 (±5.2) nm depending the reaction conditions under which they were synthesized. Furthermore, because of intense light emission, the ESNPs were used as fluorophore in a peroxyoxalate chemiluminescence system. The effect of solvent and concentrations of necessary reagents, bis(2,4,6-trichlorophenyl)oxalate, sodium salicylate, hydrogen peroxide and the effects of size of the ESNP and temperature on the luminescence efficiency of the system were examined. The activation kinetic parameters of the system were also evaluated from the temperature investigation.     

Fabrication of a renewable syringe carbon paste electrode with a motor rotary blade and using for voltammetric measurement of dipyridamole

In this work, we fabricated a new renewable syringe carbon paste electrode (SCPE) equipped with a motor rotary cutting blade and used for voltammetric determination of dipyridamole (DIP) in aqueous solution, at room temperature. The cutter rotates by a small electrical motor and easily renews the surface of the carbon paste electrode by removing the spotty surface. Electrochemical performance of the constructed electrode was investigated with cyclic voltammetry (CV) and compared to some other previously reported works. The new sensor showed several advantages such as excellent repeatability, high stability, good sensitivity and easily surface renewable. The results indicated that the presence of methyltrioctyl ammonium chloride (MTOAC) could remarkably enhance the oxidation of DIP due to feasible electrical conductivity properties in a phosphate buffer solution. At optimum conditions for the new syringe CPE, the square wave voltammetry (SWV) was used to measure the concentration of DIP in a linear range of 0.08–30.0 µM and a detection limit of 0.02 µM was obtained after 100 s of accumulation time. The sensor was then tested for the simple, rapid and sensitive electrochemical determination of DIP in real samples such as pharmaceutical formulations.