The Oxidation of Thiocyanate to Polythiocyanic Acid Using Peroxydisulfate in Aqueous Solution

Abstract

The oxidation of thiocyanate to polythiocyanic acid by peroxydisulfate was carried out in an aqueous solution at room temperature. The primary step is the decomposition of peroxydisulfate into sulfate-free radicals. At room temperature in the presence of peroxydisulfate as a oxidizing agent, HSCN polymerizes to (HSCN)_n. The oxidation of thiocyanate in an aqueous solution is often complicated, but here we obtained the polythiocyanic acid as a major product. The products were characterized by elemental analysis, IR, UV- visible, H-NMR spectroscopy, and X-ray powder diffraction.     

Ultra high performance liquid chromatography-quadrupole-time of flight analysis for the identification and the determination of resveratrol and its metabolites in mouse plasma

Resveratrol is a polyphenol that has numerous interesting biological properties, but, per os, it is quickly metabolized. Some of its metabolites are more concentrated than resveratrol, may have greater biological activities, and may act as a kind of store for resveratrol. Thus, to understand the biological impact of resveratrol on a physiological system, it is crucial to simultaneously analyze resveratrol and its metabolites in plasma. This study presents an analytical method based on UHPLC-Q-TOF mass spectrometry for the quantification of resveratrol and of its most common hydrophilic metabolites. The use of ¹³C- and D-labeled standards specific to each molecule led to a linear calibration curve on a larger concentration range than described previously. The use of high resolution mass spectrometry in the full scan mode enabled simultaneous identification and quantification of some hydrophilic metabolites not previously described in mice. In addition, UHPLC separation, allowing run times lower than 10 min, can be used in studies that requiring analysis of many samples.     

Stability, rheological, magnetorheological and volumetric characterizations of polymer based magnetic nanofluids

The Fe₃O₄ nanoparticles and Fe₃O₄ nanoparticles coated with oleic acid have been dispersed in base fluid of poly(ethylene glycol) (PEG). Stability and particle size distribution of these nanofluids have been studied by result analysis of UV–Vis spectroscopy, zeta potential and dynamic light scattering. Blue shift of UV–Vis spectra has been related to quantum effects such as band gap enlargement with particle size decreasing and also to effect of oleic acid on the ultraviolet wavelength. Flow behavior and suspension structure of Fe₃O₄ nanoparticles dispersed in PEG have been determined by rheological properties. Viscosity values of Fe₃O₄-PEG nanofluid as a function of temperature have also been investigated. The chain-like structure of Fe₃O₄ nanoparticles coated with oleic acid in base fluid of PEG has been verified by measuring the magnetorheological properties. The effect of temperature on magnetorheological properties of Fe₃O₄ nanoparticles coated with oleic acid has also been investigated in base fluid of PEG. The volumetric properties of Fe₃O₄-PEG and Fe₃O₄ coated with oleic acid–PEG nanofluids and PEG–oleic acid solution have also been measured at different temperatures to specify the suspension structure and also interactions of Fe₃O₄, PEG and oleic acid molecules.     

Extraction of methocarbamol from human plasma with a polypyrrole/multiwalled carbon nanotubes composite decorated with magnetic nanoparticles as an adsorbent followed by electrospray ionization ion mobility spectrometry detection†

In this work, a polypyrrole/multiwalled carbon nanotubes composite decorated with Fe₃O₄ nanoparticles was chemically synthesized and applied as a novel adsorbent for the extraction of methocarbamol from human plasma. Electrospray ionization ion mobility spectrometry was used for the determination of the analyte. The properties of the magnetic‐modified adsorbent were characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform IR spectroscopy, and X‐ray diffraction. The effects of experimental parameters on the extraction efficiency of the sorbent were investigated. Under the optimized conditions, the linear dynamic range was found to be 2–150 ng/mL with the detection limit of 0.9 ng/mL. The relative standard deviation was 5.3% for three replicate measurements of methocarbamol in plasma sample. The extraction efficiency of the sorbent for the determination of different drugs with various polarities was also compared to that of Fe₃O₄‐polypyrrole and Fe₃O₄‐multiwalled carbon nanotubes sorbents. Finally, the method was used for the determination of methocarbamol in blood samples.     

Kinetic analysis of the complex process of poly(vinyl alcohol) pyrolysis using a new coupled peak deconvolution method

A peak deconvolution procedure used for the analysis of data corresponding to simultaneous overlapping processes begins with separation of individual processes using functions such as Gaussian, Lorentzian, Weibull, and Fraser–Suzuki (FS) followed by application of kinetic analysis methods to the separated peaks. We propose a coupled peak deconvolution procedure to link the parameters of the FS functions of similar peaks in two DTG curves obtained at different linear heating rates, so that the coordinates of each peak can be obtained in a constrained manner. The proposed technique is a kinetic deconvolution method rather than a pure mathematical deconvolution technique. To analyze individual peaks in our study, the non-parametric kinetic and Freidman’s isoconversional methods have been applied to determine kinetic triplet of each process. This technique has been tested with both simulated and experimental data. Using this technique, the effects of molecular weight and degree of hydrolysis of polyvinyl alcohol (PVA) samples on reaction mechanism and activation energy of thermal degradation were studied. The presence of acetate group in the PVA samples causes thermal stability, decreases the rate of main reactions, and increases the activation energy. The results of this study may help tailor heat-resistant materials with proper choice of polymer characteristics.     

Schemes for Single Electron Transistor Based on Double Quantum Dot Islands Utilizing a Graphene Nanoscroll,Carbon Nanotube and Fullerene

The single electron transistor (SET) is a nanoscale switching device with a simple equivalent circuit. It can work very fast as it is based on the tunneling of single electrons. Its nanostructure contains a quantum dot island whose material impacts on the device operation. Carbon allotropes such as fullerene (C₆₀), carbon nanotubes (CNTs) and graphene nanoscrolls (GNSs) can be utilized as the quantum dot island in SETs. In this study, multiple quantum dot islands such as GNS-CNT and GNS-C₆₀ are utilized in SET devices. The currents of two counterpart devices are modeled and analyzed. The impacts of important parameters such as temperature and applied gate voltage on the current of two SETs are investigated using proposed mathematical models. Moreover, the impacts of CNT length, fullerene diameter, GNS length, and GNS spiral length and number of turns on the SET’s current are explored. Additionally, the Coulomb blockade ranges (CB) of the two SETs are compared. The results reveal that the GNS-CNT SET has a lower Coulomb blockade range and a higher current than the GNS-C₆₀ SET. Their charge stability diagrams indicate that the GNS-CNT SET has smaller Coulomb diamond areas, zero-current regions, and zero-conductance regions than the GNS-C₆₀ SET.     

Application of moiré technique to the measurement of modulation transfer functions (MTF) of printing systems

It is shown theoretically and verified experimentally that by writing a low spatial frequency Ronchi grating by a computer and printing two copies of it on two transparencies by a printer, the modulation transfer function (MTF) of the printed image can be evaluated by measuring the transmittance of the superimposed gratings in a moiré fringe spacing. Application of the technique is quite simple and the results are reasonably reproducible. The technique does not require a high sensitive intensity detector and a very narrow slit for transmission scanning. Also, the presented technique can be applied to other imaging systems.     

(Liquid + liquid) and (liquid + solid) equilibrium of aqueous two-phase systems containing poly ethylene glycol di-methyl ether 2000 and di-sodium hydrogen phosphate

(Liquid + liquid) equilibrium (LLE) for the {poly ethylene glycol di-methyl ether 2000 (PEGDME₂₀₀₀) + Na₂HPO₄ + H₂O} system have been determined experimentally at T = (298.15, 308.15, 313.15, and 318.15) K. The effects of temperature on the binodals and tie-lines for the investigated aqueous two-phase system (ATPS) have been studied. An empirical non-linear expression developed by Merchuk was used for reproducing the experimental binodal data. In this work, the three fitting parameters of the Merchuk equation were obtained with the temperature dependence expressed in the linear form with (T ? T₀) K as a variable. Furthermore, the modified local composition segment-based NRTL and Wilson models and also osmotic virial equation were used to describe the LLE data of the studied system. Also, the effects of the type of salt on LLE are discussed. In addition, the effects of end groups of the polymers PEGDME₂₀₀₀ and poly ethylene glycol 2000 on phase forming ability were studied. The complete phase diagram for the poly ethylene {glycol di-methyl ether 2000 (PEGDME₂₀₀₀) + Na₂HPO₄ + H₂O} system has also been determined at T = 298.15 K.