Abstract: ABSTRACT The purpose of this study was to determine the antioxidant and antiradical activities in aqueous and ethanol extracts of Crataegus meyeri Pojark leaf, additionally, to examine some vitamins (A, E, C), trace elements (Cu, Zn, Mn, Se, Cr, Co). In this study, vitamin C, antioxidant and antiradical properties were determined using spectrophotometer. The results are compared with the reference antioxidants such as trolox, α-tocopherol and BHT. Levels of vitamin (A, E) measured using HPLC method. Trace elements were carried out using method of dry ashing with ICP-MS. The results of this study showed that C. meyeri leaf has a high antioxidant capacity and vitamin levels. C. meyeri is thought to be used as additives for food products and pharmaceutical industries with appropriate antioxidant properties and an antioxidant in future studies of experimental animal models, against free radicals generated in response to oxidative stress.
Abstract: ABSTRACT In order to deepen understanding the interactions between ionic liquid and chitin/chitosan/cellulose at the molecular level, we have performed a study on the electronic structures, topological properties, nonconvalent interactions between 1-ethyl-3-methyl imidazolium chloride and chitin/chitosan/cellulose by using density functional theory. The results indicate that interactions between chitin/chitosan/cellulose and 1-ethyl-3-methyl imidazolium chloride are stronger that the intra-interaction of chitin/chitosan/cellulose, implying that chitin/chitosan/cellulose can dissolve in 1-ethyl-3-methyl imidazolium chloride.
Abstract: ABSTRACT To gain more information about the effect of surfactant on salicylic acid derivatives, the stoichiometric protonation constants of 5-Sulphosalicylic acid and 5-Hydroxysalicylic acid in 0.0%-2.5% (w/v) cetyltrimethylammonium bromide (CTAB) - water mixtures were determined at an ionic strength of 0.16 mol dm-3 and at 303 K. A potentiometric method was used and the calculation of constants was carried out using the computer program MINIQUAD75. These protonation constants values have been found to shift in micellar media as compared to those in pure water. The differences in the values have been attributed to the solvent properties of the interfacial and bulk phases involving contribution from the micellar surface potential in the case of charged micelles. The trend of log values of step-wise protonation constants with mole fraction of the medium have been explained based on specific solute-solvent interactions. In this study Distributions of species, percentage of species composition, protonation equilibria and effect of influential parameters on the protonation were also discussed.
Abstract: ABSTRACT Nanomaterials synthesize by different techniques exhibit excellent photocatalytic activity. These catalysts could be employed for environmental remediation, renewable energy sources, photocatalysis and many other applications in various fields. Nanophotocatalyst has been used for the treatment of hazardous materials such as industrial effluents containing complex organic compounds, dyes and metal ions successfully. The multidimensional study of composition, shape, size, surface area and nanostructure and different operating parameters like pH, concentration, temperature etc, of these photocatalyst help in current and further development of photocatalysts for different applications. The photocatalytic activity of nanoparticles has made a great contribution in providing definitive mechanistic information about the photocatalytic processes. The main aim of this review paper is to give an overview of the enhanced photocatalytic activities of titanium dioxide (TiO2) nanoparticles. This review includes the basic properties of photocatalyst and mechanim of photocatalysis process followed by unique photocatalytic properties and research of TiO2 nanoparticles as photocatalysts. An effort has also been made to give an overview of expedient photocatalytic activity of these doped nanoparticles. Many investigators have reported the enhanced photocatalytic activity by the degradation of dyes as a model compound.
Abstract: ABSTRACT Inorganic-organic hybrid structures based on metal-complexes particularly, octahedral bis-2,2′:6′,2″- terpyridine metal complexes provide an advantages of increased symmetry and in the case of ruthenium(III)/ruthenium(II) complexation an entrance to a directed complexation Method. The Ru (II) terpyridine methane thiolate protected gold nanoparticle was synthesized through covalent bonding of Ru terpyridine methane thiolates over gold nanoparticles surfaces. The ligand terpyridine methanethiolate was synthesized successfully in good percentage of yield. The structures were confirmed and characterized by different physical, analytical, spectral data like FTIR, UV, SEM and Cyclic voltammetry. All the data are shown the expected results.
Abstract: ABSTRACT In this work, a matrix based on silica xerogel, synthesized from TEOS, water, ibuprofen (as template) and acetic acid at room temperature, was used for ibuprofen (IBF) incorporation, aiming to create a drug delivery system capable of releasing this compound under a basic pH condition (considering desirable and optimal release in the intestines). The IBF release was checked at different pH values (ranging from 2 to 8), using appropriate buffered solutions. After observing the IBF release performance from the silica xerogel and its dependence on the pH, the same matrix containing IBF was submitted to a novel assay, using only a pH 7 buffered solution as the best way to check the chronological release. This was carried out at 1, 2, 5 and 10 minutes to determine aliquot removal, as well as IBF concentration at each elapsed period.
Abstract: ABSTRACT Increase in NOx emission is one of the important drawbacks for using biodiesel as an alternative for petroleum diesel. Several studies had been carried out to reduce the NOx emissions level in biodiesel. The present work is the result of an attempt wherein ferrofluid is added to rice bran oil methyl ester in the way of analyzing its effects on emission characteristics. Magnetite concentrate is exothermic and is known for its characteristics of releasing copious heat at higher temperatures. Nanofluid using magnetite was synthesized by reacting Iron II (FeCl2) and Iron III (FeCl3) in an aqueous ammonia solution to form Magnetite Fe3O4 (Ferro fluid). Release of heat by magnetite during the combustion process would counterbalance the conventional limitations related with biodiesel such as increased delay period, inferior combustion rate and higher NOx emissions etc. Experiments were conducted with Rice Bran Oil Methyl Ester (RBOME) and Rice Bran Oil Methyl Ester with addition of ferrofluid (RBOMEF) and are compared with petroleum diesel. RBOMEF was prepared comprising 97.7% biodiesel, 2% magnetite based ferrofluid and 0.3 % surfactant by volume was used in a Compression Ignition engine. The experimental analysis found a decrease in HC, CO and NOx emissions of 10.8%, 9.1% and 8.49% respectively.
Abstract: ABSTRACT The iron-manganese mixed monolithic catalysts were obtained by impregnation from nitrates as precursors. A monolithic support was studied with and without alumina as surface generator. The characterization consisted in XRD, SEM, Adherence test, SBET and TPR. The monolith was evaluated in the combustion of ethyl acetate. The preparation method was very satisfactory in terms of reproducibility and adherence of the deposited phase. The higher activity of IFeMnx with respect to Al3FeMnx may be attributed for the formation of the solid solution where the Fe is introduced to the bixbyite structure. However, the presence of defective MnOx species in monoliths without alumina which might help to improve their performance is observed.
Abstract: ABSTRACT Water resistance, mechanical properties, and limiting oxygen index (LOI) of wood plastic composites (WPCs) and neat polypropylene filled with different amounts (3, 6, and 9% by weight) of dolomite powder and wood flour (15 and 30 by weight) were investigated. Wood flour, dolomite powder, polypropylene, and wax were dry-mixed in a high-intensity mixer to produce a homogeneous blend. This blend was then compounded in a laboratory-scale single screw extruder. Test specimens were produced by injection moulding process from the pellets dried to moisture content of 1%. The thickness swelling and water absorption of the dolomite polypropylene composites (DPCs) and WPCs slightly increased with increasing dolomite powder content but the differences were not significant. The flexural modulus and tensile modulus of the WPCs and DPCs increased with increasing dolomite powder content while the flexural strength and tensile strength slightly decreased. The LOI of the WPCs and DPCs increased with increasing dolomite powder content, which extended the times to ignition of WPC and polypropylene. Based on the findings obtained from the present study, it can be said that 6 wt% dolomite powder is the optimum amount in the manufacture of WPC and DPC.
Abstract: ABSTRACT Carbon paste electrodes modified with a family of ionic liquids (as binders) derived from N-octyl-pyridinium hexafluorophosphate, (composite-ionic liquid electrodes (CILEs)) were studied toward the oxidation of sulfite as an inner-sphere probe reaction and compared to a conventional carbon paste electrode (CPE) in which the binder was mineral oil. The ionic liquids were modified at para-position with substituents that are electron withdrawing: -CN (CILE/CN) and −CF3 (CILE/CF3) and substituents that are electron donating: -CH3 (CILE/CH3) and −OCH3 (CILE/OCH3), and compared with the ionic liquid without substituents (CILE/OPy). The results showed that CILEs are capable of catalyzing the sulfite oxidation, shifting the oxidation potential to more negative values compared to CPE. Also, they showed linear correlations between increasing sulfite concentration and increasing current density. The best system in terms of sensitivity was the electrode modified with the 4-methyl-N-octylpyridiniumhexafluorophosphate CILE/CH3 and, then, that modified with the non-substituted ionic liquid CILE/OPy measured by amperometry. In terms of potential, the best systems are the CILEs modified with ILs with inductive-substituents, -CH3 and −CF3 and OPy, indicating that the delocalization of the charge of the cation produced by the mesomeric-substituent (-OCH3, -CN) diminishes the electrocatalytic behavior of these binders for that oxidation. On the other hand, the analytical parameters of all the amperometric sensors studied here (all CILEs excepts CILE/OCH3) are good enough to be applied in food industry for samples without polyphenols at concentrations higher than ca. 1mM of sulfite. Their stability is very high (at least 100 cycles after obtaining a stable response without changing its current, exposed to air and humidity) and they can be used to remove sulfite from wastewaters. Finally, to our knowledge, there are not comparative studies about the effect of changing the substituent of the cation in electrocatalysis of modified IL-electrodes.
Abstract: A glassy carbon electrode was modified by drop-coating technique using 1,4,10,13-Tetraoxa-7,16-diazaciclooctadecano (diaza-18 -crown-6 or DA18C6) and Nafion (NF) for the determination of Pb (II) by square wave anodic stripping voltammetric (SWASV). The new electrode exhibits an increase in due to major pre-concentration of aza crown ether and ionic exchange of NF with metal cations. Optimal conditions were: 3 mmol L-1 DA18C6, 3 wt % NF, 10 mmol L-1 HCl as supporting electrolyte, a frequency of 15 Hz, an accumulation time of 300 s and an accumulation potential of -0.80 V. The detection limit was 0.09 μg L-1 and linear range was 10-50 μg L-1. Interference from metal ions such us Fe (II), Pb (II), Cd (II) and Cu (II) was also studied. The method is sensitive, selective and simple with a relative standard deviation of 11%.
Abstract: ABSTRACT A new macrocycle Schiff base, by the reaction between benzene-1,2-diamine and 3-bromo-pentane-2,4-dione, is introduced and a series of its complexes with Co(II), Ni(II), Cu(II) and Zn(II) have been synthesized. FTIR, 1H and 13C NMR, and TGA, also biological activities of all complexes and the electronic spectral data have been investigated. The results show that there are no water molecules, also that macrocycle Schiff base is bonded to the metal ions through nitrogen atoms of four azomethine groups via an octahedral arrangement containing N4 tetra-dentate donor sites on planar and two Cl atoms occupying the other two opposed sites. The corresponding Cu(II) and Zn(II) complexes showed good antibacterial and antifungal activities. The molecular geometry, frontier molecular orbitals and Mulliken atomic charge of the compounds are investigated theoretically using DFT method.
Abstract: ABSTRACT Thermal degradation of Poly(ethylene terephthalate) (PET) bottles waste was carried out by glycolysis using triethyleneglycol (TEG) as nucleophilic agent and N1,N2-bis(2-aminobenzyl)-1,2-diaminoethane zinc(II) (ABEN), in order to test this compound as catalyst in the degradation of PET until to obtain short chains of polyester (oligomers). The depolymerization processes was tested at 180, 190 and 210 °C, and two molar ratios of PET:TEG (1:1.3 and 1:2.6), the amount of catalyst used was fixed at 1% in relation to PET, the best experiment of PET glycolysis was found at 190 °C during two hours in a mass relation PET:TEG 1:1.3. All products were analyzed by Fourier transform infrared spectroscopy (IR), gel permeation chromatography (GPC) and differential scanning calorimetry (DSC), the behavior of the reaction rate was studied for the best experiment by measuring the amount of degraded PET at different glycolysis time. The degradation of PET was favored with the use of ABEN, which accelerates the reaction, obtaining oligomers in the absence of an organic solvent or reaction medium, this is the most efficient catalyst found so far. The oligomers were obtained with molecular weight between 900 and 1500 g mol-1 depending on the reaction time, 60 min was the less time of the total glycolysis of PET. Also was found that the molecular weight of the oligomers increased along the glycolysis, due to the recombination with TEG and ethylene glycol produced in degradation.
Abstract: ABSTRACT The mononuclear cobalt (III) complex derived from 1,10-phenanthroline with lactose [Co(phen)2lactose]Cl2·3H2O (1) has been prepared and its properties have been compared with the sucrose complex [Co(Phen)2sucrose]Cl2·3H2O(2) and the complex without carbohydrate [Co(Phen)2Cl2]Cl·3H2O(3). The chemical structure of (1) was assigned by 1H-NMR, IR, CD and UV-Vis spectral data. The antibacterial activity of (1) - (3) was evaluated by disc-diffusion assays, using Gram-negative and positive bacteria. The minimum inhibitory concentration of the three complexes on the studied bacteria and their cytotoxicity on HEK293 human cells was determined. A colorimetric plate assay was used to distinguish bacteriostatic from bactericidal effect. Finally, the complexes uptake mechanism was evaluated using bacteria with mutated genes that encode for carbohydrate and siderophore receptors. The results indicate that complex (1) has an antibacterial activity similar to (3), while (2) presents a more restricted one. Moreover, all three complexes act by a bacteriostatic effect against bacterial cells and both (1) and (3) use a siderophore uptake mechanism to enter on bacterial cytoplasm. Cytotoxicity assays show that carbohydrate complexes are not cytotoxic to human cells, in contrast with complex (3), which is highly toxic. These results suggest that the use of the lactose ligand would maintain the antibacterial activity and uptake mechanism of the complex at reasonable levels, and would also reduce its toxicity against human cells. Thus, its strategic use would allow a decrease in toxicity of complexes used in eventual studies on eukaryotic systems.
Abstract: ABSTRACT The activity of Fe2O3/Al2O3 catalysts prepared by impregnation of Al2O3 with different amounts of Fe and calcination temperatures (650 and 900 °C) in the direct N2O decomposition reaction was studied. High calcination temperature was introduced to study the effect of “aging”, which are the conditions prevailing in the process-gas option for N2O abatement. The catalysts were characterized by BET, XRD, UV-DRS, and H2-TPR. The incorporation of Fe promotes the alumina phase transition (γ-Al2O3 to α-Al2O3) when the catalysts are calcined at 900 °C, which is accompanied by a decrease in the specific area. The activity of the catalysts and the specific surface area depend on Fe loading and calcination temperature. It was found that highly dispersed Fe species are more active than bulk type Fe2O3 particles. We conclude that Fe2O3/Al2O3 catalysts prepared by impregnation method are active in the decomposition of N2O, to be used at low or high reaction temperatures (tail-gas or process-gas treatments, respectively), as part of nitric acid production plant.
Abstract: SUMMARY One of the applications of chitosan is based on its ability to stabilized metallic nanoparticles with minimum chitosan metal molar ratio. This work describes the synthesis and characterization of Ag, Au, Pt, and Cu nanoparticles stabilized by chitosan through chemical reduction of metallic salts by sodium borohydride (NaBH4). The properties of bionanocomposites were studied in terms of their surface plasmon resonance, crystalline structure, average diameter size, particle distributions and functional groups. The samples were characterized by TEM, electron diffraction, UV-Visible and FTIR. The stability of the colloids at room temperature were also measured. A high stability for the colloidal dispersion with chitosan can be observed (> three months). We found that TEM studies show a size distribution between 6 and 10 nm, depending on metals and chitosan metal relation. Electron diffraction analysis for the metallic nanoparticles shows the presence of Ag, Au, Pt and Cu. The FT-IR exhibit the presence of the chitosan in the stabilisation of metallic nanoparticles.
Abstract: ABSTRACT Several research to explore the possible conversion of CO2 using rhenium(I) tricarbonyl complexes have been reported the last years. In the present work, we investigated a potential use of fac-Re(CO)3(4,4′-di-methyl-2,2′-bipyridyl)L+ complex (C2), where L is an electron-withdrawing ancillary ligands which present an intramolecular hydrogen bond (IHB), in a preliminary electrocatalytic reduction of CO2. The C2 complex was synthesized and characterized according to reported methods earlier. The cyclic voltammogram profile for the C2 complex were studied in dichloromethane under inert atmosphere, and it shows a typical behavior for an electrocatalytic process, the C2 complex illustrate the electrochemical reaction mechanism corresponds to an electrochemical–chemical–electrochemical pathway (ECE). Also, a Vitreous Carbon plate used as working electrode was employed and modified by cycling the anodic region of C2 in CH2Cl2 which involve the oxidative redox response for the −NH2 and −OH groups. The voltammogram profile involve shows a polymeric deposit on the plate surface in a CO2 saturated solution (pH=7.0). A strong electrocatalytic discharge of current is obtained with a wave foot of -1.3 V showing that C2 have the potential to be used in electrocatalyst CO2 reduction.
Abstract: ABSTRACT Single crystals of 1,3-bis(cyanomethoxy)calix[4]arene (1) were grown from Chloroform/Methanol mixture and these were nanodecorated with colloidal gold nanoparticles (AuNps). The single crystals were then characterized by single-crystal X-ray diffraction (XRD) and Scanning Electronic Microscopy (SEM). The nanodecorated crystals were characterized by UV-Visible Absorption Spectroscopy, Transmission Electronic Microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). In this work, it is shown that the stabilization of the nanoparticles occurs through of the interactions of these with the nitrile group, maintaining their shape and size.
Abstract: ABSTRACT The effect of supports and the addition of CS2 in the feed were studied on hydrodenitrogenation of Quinoline in a continuous flow reactor over ReS2/support catalysts at 300, 325 and 350 °C and 3MPa of H2. The ReS2 supported on TiO2 displayed the highest activity followed by ZrO2, γ-Al2O3 and SiO2 supports. The activity trend was correlated with the Re dispersion on the support. The effect of the addition of CS2 was increased activity until 2.5 v/v % content. At higher CS2 content the activity decreased due to competitive adsorption between CS2 and Quinoline on the active sites.
Abstract: ABSTRACT The effects of temperature, pH and agitation time (equilibrium) on the adsorption process of different pesticides on N3P3(OC6H4COOCH2CH2CH3)6 was studied. With optimal conditions experimental, the adsorption isotherms have been realized with through Langmuir and Freundlich models. Pesticides are compounds used mainly in agriculture to control various species (plants, insects, worms, fungi). Due to their physicochemical properties, they can remain for a long time in the application sites, bioaccumulating and moving between environmental compartments which generate various environmental problems. The results obtained showed a physisorption mechanism for the five pesticides studied, with higher sorption for: azinphos methyl (93,5 mg kg-1), carbaryl (290.5 mg kg-1) and carbofuran (580.5 mg kg-1) at 20 ° C, according to the models used.
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