Semi-empirical study of ortho-cresol photo degradation in manganese-doped zinc oxide nanoparticles suspensions

ABSTRACT: The optimization processes of photo degradation are complicated and expensive when it is performed with traditional methods such as one variable at a time. In this research, the condition of ortho-cresol (o-cresol) photo degradation was optimized by using a semi empirical method. First of all, the experiments were designed with four effective factors including irradiation time, pH, photo catalyst's amount, o-cresol concentration and photo degradation % as response by response surface methodology (RSM). The RSM used central composite design (CCD) method consists of 30 runs to obtain the actual responses. The actual responses were fitted with the second order algebraic polynomial equation to select a model (suggested model). The suggested model was validated by a few numbers of excellent statistical evidences in analysis of variance (ANOVA). The used evidences include high Fvalue (143.12), very low P-value (<0.0001), non-significant lack of fit, the determination coefficient (R2 = 0.99) and the adequate precision (47.067). To visualize the optimum, the validated model simulated the condition of variables and response (photo degradation %) by a few number of three dimensional plots (3D). To confirm the model, the optimums were performed in laboratory. The results of performed experiments were quite close to the predicted values. In conclusion, the study indicated that the model is successful to simulate the optimum condition of o-cresol photo degradation under visible-light irradiation by manganese doped ZnO nanoparticles.     

Water dynamics in a lithium chloride aqueous solution probed by Brillouin neutron and x-ray scattering

We studied the collective excitations in an aqueous solution of lithium chloride over the temperature range of 270-205 K using neutron and x-ray Brillouin scattering. Both neutron and x-ray experiments revealed the presence of low- and high-frequency excitations, similar to the low- and high-frequency excitations in pure water. These two excitations were detectable through the entire temperature range of the experiment, at all probed values of the scattering momentum transfer (0.2 ?(-1) < Q < 1.8 ?(-1)). A wider temperature range was investigated using elastic intensity neutron and x-ray scans. Clear evidence of the crossover in the dynamics of the water molecules in the solution was observed in the single-particle relaxational dynamics on the μeV (nanosecond) time scale, but not in the collective dynamics on the meV (picosecond) time scale.     

Green biosynthesis of silver nanoparticles using Callicarpa maingayi stem bark extraction

Different biological methods are gaining recognition for the production of silver nanoparticles (Ag-NPs) due to their multiple applications. The use of plants in the green synthesis of nanoparticles emerges as a cost effective and eco-friendly approach. In this study the green biosynthesis of silver nanoparticles using Callicarpa maingayi stem bark extract has been reported. Characterizations of nanoparticles were done using different methods, which include; ultraviolet-visible spectroscopy (UV-Vis), powder X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray fluorescence (EDXF) spectrometry, zeta potential measurements and Fourier transform infrared (FT-IR) spectroscopy. UV-visible spectrum of the aqueous medium containing silver nanoparticles showed absorption peak at around 456 nm. The TEM study showed that mean diameter and standard deviation for the formation of silver nanoparticles were 12.40 ± 3.27 nm. The XRD study showed that the particles are crystalline in nature, with a face centered cubic (fcc) structure. The most needed outcome of this work will be the development of value added products from Callicarpa maingayi for biomedical and nanotechnology based industries.     

<Emphasis Type="Italic">N</Emphasis>-Bromo Reagent Mediated Oxidation of Urazoles to Their Corresponding Triazolinediones under Mild and Heterogeneous Conditions

Summary. Various N-bromo reagents [HMTAB, DABCO-bromine, DPTBE, and TBCA] were used as effective oxidizing agents for the oxidation of urazoles and bisurazoles to their corresponding triazolinediones under mild and heterogeneous conditions at room temperature with good to excellent yields. Also the oxidation of some new 4-phenylurazole derivatives with these reagents is discussed.     

Fe(HSO4)3·SiO2 as an efficient,heterogeneous and recyclable catalyst for the synthesis of bis-(β-enaminones) and bis-(β-enamino esters)

Fe(HSO₄)₃·SiO₂ is used to catalyze the condensation of β-diketones and β-keto esters with aromatic and aliphatic diamines in solvent-free conditions at room temperature. This afforded the corresponding bis-(β-enaminones) and bis-(β-enamino esters) in very good to excellent yields. Short reaction times, easy work-up procedure, and reusability of the catalyst are the merits of this study.     

One‐pot,Green and Efficient Synthesis of 3,4‐Dihydropyrimidin‐2(1H)‐ones or Thiones Catalyzed by Citric Acid

One‐pot three‐component condensation of ethyl acetoacetate, aldehyde and urea or thiourea in refluxing ethanol in the presence of catalytic amounts of citric acid afforded the corresponding 3,4‐dihydropyrimidin‐2(1H)‐ones/thiones in high yields. The catalyst is reusable and can be applied several times without any decrease in product yield.     

Synthesis and Characterization of Silica Nanostructures in the Presence of Schiff-Base Ligand Via Simple Sonochemical Method

Silica nanostructures were synthesized on the basis of modified Stöber procedure via a sonochemical method and the reaction between tetraethyl orthosilicate (TEOS), ethylenediamine (en) and methanol in water, in the attendance of Schiff-base ligand (H₂Salen) as capping agent. The effects of synthesis parameters such as: sonochemical irradiation time, sonochemical power and molar aspect ratio of Schiff-base ligand to TEOS were considered to achieve optimum situation. It was established that particle size, morphology and phase of the products could be affected by these parameters. The as synthesized silica nanostructures were characterized by X-ray powder diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, and X-ray energy dispersive spectroscopy.     

DABCO,A REAGENT FOR DEPROTECTION OF BENZYLIC TRIMETHYLSILYL ETHERS UNDER MICROWAVE IRRADIATION IN A SOLVENTLESS SYSTEM

Deprotection of trimethylsilyl ethers of benzylic alcohols to the corresponding alcohols using 1,4-diazobicyclo[2,2,2]octane (DABCO) under microwave irradiation under solvent-free conditions is reported.     

The equilibrium melting temperature and isothermal crystallisation kinetics of cyclic poly(butylene terephthalate) and styrene maleimide (c-PBT/SMI) blends

The equilibrium melting point ( $ T_{\text{m}}^{0} $ ) and isothermal crystallisation kinetics of cyclic poly(butylene terephthalate) (c-PBT) and styrene maleimide (SMI) blends prepared by solid dispersion and in situ polymerisation of cyclic butylene terephthalate oligomers (CBT) within SMI were investigated. This c-PBT/SMI blend is a miscible semicrystalline–amorphous blend system. The $ T_{\text{m}}^{0} $ of c-PBT/SMI blends was determined using the Hoffman and Weeks method, while Avrami crystallisation kinetic model have been applied to study their isothermal crystallisation kinetics. It was found that $ T_{\text{m}}^{0} $ decreased with increasing SMI content in the blend compositions. All the crystallisation exotherms were obtained from differential scanning calorimetry under isothermal experimental conditions. The average value of Avrami exponent, n, is in the range of 2.4–2.8 for the primary crystallisation process for c-PBT and its blends, which suggest that heterogeneous nucleation of spherulites occurred and growth of spherulites was between two-dimensional and three-dimensional.