Influence of the temperature of positive ions on the sheath formation and parameter space region in magnetized electronegative plasmas

The parameter space regions and the sheath formation in an electronegative discharge in the presence of thermal positive ions and oblique magnetic field are investigated. It is assumed that the negative species are in thermal equilibrium and the positive ions have a finite temperature. Three regimes of uniform, multilayer stratified and pure stratified are found as functions of positive and negative ion temperature, electronegativity and the magnetic field. The influence of positive ion temperature in the presence of magnetic field on the profiles of the positive ion density, positive ion velocity and electric potential are investigated. The positive ion flux at the sheath edge as a function of magnetic field is obtained for different collisionality and positive and negative ion temperatures. Finally, the influence of the magnetic field, collision frequency and the positive ion temperature on the parameter space regions are discussed.     

A comparison between optical properties of TiO2 nanowires obtained by EMA method and experiment

Optical properties of TiO₂ nanowires, synthesized by two-step thermal evaporation process, have been studied experimentally and theoretically. Based on the theoretical method optical constants of nanowires have been calculated with the use of the effective medium approximation (EMA). As evidenced by X-ray diffraction patterns our synthesized nanowires, whose diameters and lengths were within the ranges of 50-90 nm and 500-1500 nm, respectively, were found to be crystalline rutile TiO₂ with the major refraction being along the (1 1 0) direction. The experimental data of the reflectance of TiO₂ nanowires has been obtained using spectrometer in wavelength 250-800 nm, and then, compared with the spectrum of reflectance predicted by the EMA theoretical model. Our measured experimental optical data has been found to be in good accord with our predicted results spectrum with the use of the EMA modeling; this agreement indicates that our estimation of the volume fraction from atomic force microscopy (AFM) data was accurate.     

Development of cloud point extraction using pH-sensitive hydrogel for preconcentration and determination of malachite green

A novel and sensitive cloud point extraction procedure using pH-sensitive hydrogel was developed for preconcentration and spectrophotometric determination of trace amounts of malachite green (MG). In this extraction method, appropriate amounts of poly(styrene-alt-maleic acid), as a pH-sensitive hydrogel, and HCl were added respectively into the aqueous sample so a cloudy solution was formed. The cloudy phase consists of hydrogel particles distributed entirely into the aqueous phase. Organic or inorganic compounds having the potential to interact with polymer particles (chemical interaction or physical adsorption) could be extracted to cloudy phase. After centrifuging, these particles of hydrogel were sedimented in the bottom of sample tube. The sedimented hydrogel-rich phase was diluted with acetonitrile and its absorbance was measured at 617 nm (λ_max of malachite green in hydrogel). Central composite design and response surface method were applied to design the experiments and optimize the experimental parameters such as, concentration of hydrogel and HCl, extraction time and salting out effect. Under the optimum conditions, the linear range was 1 × 10⁻⁸-5 × 10⁻⁷ mol L⁻¹ malachite green with a correlation coefficient of 0.992. The limit of detection (S/N = 3) was 4.1 × 10⁻⁹ mol L⁻¹. Relative standard deviation (RSD) for 7 replicate determinations of 10⁻⁷ mol L⁻¹ malachite green was 3.03%. In this work, the concentration factor of 20 was reached. Also the improvement factor of the proposed method was 23. The advantages of this method are simplicity of operation, rapidity and low cost.     

Preparation and biological evaluation of radiolabeled-folate embedded superparamagnetic nanoparticles in wild-type rats

In this study, superparamagnetic iron oxide nanoparticles (SPION) embedded by folic acid (SPION-folate) were prepared by a modified co-precipitation method. The structure, size, morphology, magnetic property and relaxivity of the SPION-folate were characterized systematically by means of XRD, VSM, HRSEM and TEM and the interaction between folate and iron oxide (Fe₃O₄) was characterized by FT-IR. The particle size was shown to be ≈5–10 nm. To ensure biocompatibility, the interaction of these SPION with mouse connective tissue cells (adhesive) was investigated using an MTT assay. Consequently, gallium-67 labeled nanoparticles ([⁶⁷Ga]-SPION-folate) were prepared using ⁶⁷Ga with a high labeling efficiency (over 96%, RTLC method) and they also showed an excellent stability at room temperature for at least 2 days and were evaluated for their biodistribution in normal rats up to 24 h compared with free Ga³⁺ cation and [⁶⁷Ga]-SPION biodistribution. The biodistribution of the tracer among 3 other folate tracers were compared, showing lower liver uptake and higher blood circulation after 24 h leading to better bioavailability. The bone:muscle, kidney:muscle, lung:muscle, stomach:muscle ratios were 9.3, 9.32, 7.6 and 5.83 respectively. The developed folate-containing nano-system can be an interesting folate receptor tracer, capable of better cell membrane permeability while possessing paramagnetic properties for thermotherapy.     

Preparation of Silica Nanoparticles from Organic Laboratory Waste of Silica Gel HF254 and Their Use as a Highly Efficient Catalyst for the One‐Pot Synthesis of 2,3‐Dihydro‐1H‐isoindolone Derivatives

Reaction of an isocyanide with an iminium ion intermediate, formed by reaction between 6‐formyl‐2,3‐dimethoxybenzoic acid and secondary amines (dibenzyl‐ or benzyl(isopropyl)amine) in the presence of silica nanoparticles (silica NPs, ca. 70 nm) proceeds smoothly at room temperature to afford 2,3‐dihydro‐1H‐isoindolone derivatives in high yields.     

Magnetic fluid hyperthermia: focus on superparamagnetic iron oxide nanoparticles

Due to their unique magnetic properties, excellent biocompatibility as well as multi-purpose biomedical potential (e.g., applications in cancer therapy and general drug delivery), superparamagnetic iron oxide nanoparticles (SPIONs) are attracting increasing attention in both pharmaceutical and industrial communities. The precise control of the physiochemical properties of these magnetic systems is crucial for hyperthermia applications, as the induced heat is highly dependent on these properties. In this review, the limitations and recent advances in the development of superparamagnetic iron oxide nanoparticles for hyperthermia are presented.     

L-Gel Formulation and Decontamination Reaction of Its Active Ingredient (Oxone) Against Mustard and VX Nerve Agent Simulants

Abstract

L-Gel is an effective decontamination reagent against chemical and biological warfare agents. To achieve optimized formulation of L-Gel, several formulations with different proportional amounts of oxone (oxidizer) and Cab-O-Sil (gelling agent) were prepared and their viscosities and densities were measured. Final optimized formulation of gel was obtained as a 0.25 M aqueous solution of oxone gelled with 13%W/W of Cab-O-Sil EH-5. The L-Gel active ingredient (oxone) was tested against O,O,S-triethyl phosphorothioate (TEPT) as VX simulant and methyl phenyl sulfide (MPS) and chloroethyl phenyl sulfide (CEPS) as HD simulants. Decontamination of TEPT by a 10-fold excess amount of oxone was completed within 7.5 min with a kinetic rate constant of 0.097 S^?1. In the presence of oxone, MPS was converted to methyl phenyl sulfoxide and methyl phenyl sulfone with a higher reaction rate than CEPS, decontaminated product of which was chloroethyl phenyl sulfone.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.

GRAPHICAL ABSTRACT      

Synthesis and characterization of nickel sulfide nanoparticles via cyclic microwave radiation

In current study, nanoparticles of NiS were synthesized by applying microwave radiation. The effect of concentration of sulfur source, reaction time, and power of microwave irradiation on the treatment process was investigated. The morphology, structure, and composition of the as-synthesized nanostructures have been confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Optical properties of as-prepared sample were investigated by photoluminescence spectroscopy; the emission peak is at 555.04 nm and shows the blue shift.