Abstract: ABSTRACT Clay/nylon 6,6 nanocomposites were prepared via solution casting technique. Kaolin clay was used as filler in polymer matrix. The morphological study presented that clay particles were dispersed and embedded well in nylon 6,6 matrix. The thermal stability of the clay/nylon 6,6 nanocomposites (20-50 °C) were higher than neat nylon 6,6 polymer. The polarized optical microscopy (POM) analyses showed that the spherulites size of clay/nylon 6,6 nanocomposite reduced highly as compare to neat nylon 6,6. The decrease in size of spherulites after loading the clay is might due to nucleation effect of kaolin clay in the nylon 6,6 polymer. The mechanical properties of nanocomposite were decreased as increased kaolin amount. The solvent uptake study presented that the nanocomposite uptake was low as compared to neat nylon 6,6. It was also found that the solvent uptake decreased as increased the amount of kaolin in nylon 6,6.
Abstract: ABSTRACT Enantioseparation of nine extensively used chiral pharmaceutical substances from different pharmacological classes and with different structural characteristics has been investigated by capillary zone electrophoresis using Captisol® (sulfobuthylether-β-cyclodextrin sodium salt) as chiral selector. The influence on the chiral separation of several parameters including pH and concentration of the background electrolyte, chiral selector concentration, applied voltage, system temperature and injection parameters were studied and optimized in order to obtain increased chiral resolution and shorten analysis time. The results were compared with those obtained with native and derivatized neutral cyclodextrins (β-cyclodextrin and hydroxypropryl-β-cyclodextrin). All model molecules were resolved using Captisol® as chiral additive and optimized electrophoretic conditions, proving the efficiency of this anionic derivative of β- cyclodextrin as chiral selector in capillary electrophoresis.
Abstract: ABSTRACT A simple and isocratic HPLC method with stability indicating nature was developed and then subsequently validated for simultaneous determination of ciprofloxacin and dexamethasone in pharmaceutical formulations, human serum and urine. Best chromatographic separations were attained within run time of 10 minutes using C8 as stationary phase and mixture of phosphate buffer and methanol (41:59 v/v) as mobile phase. The mobile phase was flowed at 1.5 mL min−1 with detection of both the analytes at 270 nm using photodiode array detector. Validation of the method was accomplished using specificity, linearity, accuracy, precision, robustness, LOD and LOQ. The method was found linear from 3-21 mg mL−1 for ciprofloxacin (r2 ≥ 0.999) and 1-7 mg mL−1 for dexamethasone (r2 ≥ 0.999). The %age recoveries of ciprofloxacin in spiked human urine and serum were ≥99% and ≥85% respectively, while for dexamethasone they were ≥97% in both matrices. The method proficiently separated the peaks of ciprofloxacin and dexamethasone from all types of interfering substances including degradation products/impurities with purity index ≥ 0.9998. The method thus was stability-indicating and can be employed for simultaneous analysis of ciprofloxacin and dexamethasone in complex matrices involving multiple components in the mixture.
Abstract: ABSTRACT We report here a facile, mild and efficient synthesis of functionalized tetrahydropyrimidine quinolones via one pot three-component condensation of aromatic aldehydes, N,N-dimethyl barbituricacid (barbituricacid), 4-hydroxy-1-methylquinolin-2(1H)-one and using a cerium ammonium nitrate (CAN) as a green catalyst in aqueous media-water (as a green ideal solvent) is described. The significant advantages of this protocol are short reaction time, simple work up procedure and reduced environmental impact, wide substrate scope; generally very good to excellent yields and starting materials are inexpensive and commercially available. The structures of these compounds were established on the basis of IR, 1H NMR, 13C NMR spectra.
Abstract: ABSTRACT The essential oil content in the fruits of Artemisia aucheri growing wild in south of Iran was found to be 2.4% (v/w). The essential oil was analyzed by gas chromatography (GC) and GC–mass spectrometry (GC–MS). Characterization of individual components was performed using a commercial mass spectrometry library, and twenty nine components, representing 89.0% of the fruits essential oil were identified. This analysis showed the presence of three volatile components, including camphor (46.5%) and 1,8-cineol (23.4%) as the main compounds.
Abstract: ABSTRACT Indole-based tetraarylimidazoles were prepared by multicomponent reaction of substituted 2-arylindole-3-carbaldehydes, benzil, substituted anilines and ammonium acetate in acetic acid. The new compounds were evaluated for their antiurease and antioxidant activity. The synthesized compounds exhibited potent antiurease activity.
Abstract: ABSTRACT In the present study, general and versatile method for the functionalization of silica coated Fe3O4 nanoparticles by surface carboxylic group have been established. We have shown that malic acid functionalized magnetic nanoparticles (MA-MNPs) are an effective sorbent material for toxic metals such as cadmium and nickel. This magnetic sorbent was characterized by X-ray diffraction, scanning electron microscope and infra-red spectra. The adsorption of all studied metal ions onto Malic acid functionalized magnetic nanoparticles was found to be dependent on pH. Batch adsorption equilibrium was very fast under optimum conditions and maximum monolayer capacity, Qm, obtained from Langmuir isotherm for Cd2+ and Ni2+ were 81.627 and 63.995mgg−1, respectively at 25°C. Adsorption data were fitted well to Langmuir and Freundlich isotherm (R2 ≈ 0.99). The malic acid grafted on Fe3O4@SiO2 enhanced the adsorption capacity because of the complexing abilities of the multiple hydroxyl and carboxyl groups with metal ions.
Abstract: ABSTRACT Nonsteroidal anti-inflammatory drugs are widely used by humans as therapeutic agents to treat or prevent illnesses. Once ingested, part of them is excreted and enters the wastewater treatment plants generating biosolids that they may be used as fertilizing complements. The purpose of this study was to investigate the mobility of nonsteroidal anti-inflammatory drugs (ketoprofen, naproxen, diclofenac and ibuprofen) in soils and soils amended with biosolid. Studies of NSAIDs adsorption on two different soils were carried through batch equilibrium at room temperature. The mobility of NSAIDs in soils was studied through the use of leaching columns incorporating in the top section soil enriched with NSAIDs with and without biosolid. Ketoprofen, naproxen and ibuprofen were determined in the leaching columns. Anti-inflammatory mobility in the soil profile depends on the specific characteristics of each system soil-biosolid. In both soils there was little mobility of anti-inflammatory in the soil profile. In Linderos soil were found in greater quantity of Ibuprofen, naproxen and diclofenac that in Lonquén soil.
Abstract: ABSTRACT A variety of organic compounds and their metabolites used in pharmaceutical and personal care products (PPCP´s) are continuously introduced into the environment by domestic or industrial wastewater. Solid phase extraction (polymeric dinivylbenzene cartridge) and stir bar sorptive extraction (polydimethylsiloxane phase) methodologies were optimized for the determination of some selected PPCP´s in aqueous matrices. Carbamazepine, β estradiol, 3-(4-methylbenzylidene)champhor, benzophenone-1 and ibuprofen were extracted from aqueous samples and methanol was used as conditioning/eluting solvent. The variables involved in the extraction of the analytes in the original sample were studied, pH between 3 and 6 and sample volume between 50 and 500 mL were considered. Three concentration levels were extracted at the optimal conditions of pH 5 and 500 mL of sample volume with a recovery up to 89%. The determination was performed in a GC-MS, and a derivatization step using BSTFA+TMCS (99:1) was needed previous to the injection. Real samples from Maipo River and Villarrica Lake were analyzed with the optimized method, and concentrations below the detection limit were detected.
Abstract: ABSTRACT In this work, four secondary metabolites were isolated from leaves of Pachystroma longifolium (Euphorbiaceae): loliolide, gallic acid, methyl protocatechuate and ethyl gallate. Their structures were established by physical and spectroscopic methods. The extracts of P. longifolium and the purified compounds were tested as cathepsins inhibitors and the extracts were active.
Abstract: ABSTRACT In this study, performance of nano structure Co/γ-Al2O3 catalysts in partial oxidation of butane was investigated. The catalysts were produced through chemical reduction and incipient wetness impregnation methods. Prepared catalysts were characterized with X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM),N2 adsorption/desorption (BET), temperature programmed reduction (TPR) and thermal gravity analysis (TGA). The characterization results confirmed the uniform dispersion of Co nanoparticles over γ-Al2O3 by using chemical reduction. Butane conversion, H2 and CO selectivities increased by decreasing of Co particle size due to higher dispersion and reducibility. The optimum value of H2/CO ratio of 2 obtained from chemical reduction technique. The results showed that the stability of catalyst produced by chemical reduction method was higher than incipient wetness impregnation ones.
Abstract: ABSTRACT A novel decavanadate salt, [V0.50(H2O)5]2[H2(V10O28)]·4(H2O), was obtained by the reaction of NH4VO3 with chinhydrone in an acidic medium. The title compound was characterized in the solid and solution phases by FT-IR, single crystal X-ray diffraction, voltammetry, UV-Vis., EPR and NMR measurements. The crystal data of the compound are: H30O42V11, triclinic, Pī, a = 8.4906 (4) Å, b = 10.4236 (5) Å, c = 11.2861 (6) Å, α = 68.490 (4)°, β = 87.251 (4)°, γ = 67.145 (4)°, V = 851.11 (8) Å3, and Z = 1. In the structure, [H2(V10O28)]4− anion is bound via hydrogen bonds to the dimer state of [V0.50(H2O)5]2+ cations and the water molecules. At this dimer moiety, it has been thought that the oxygen atoms of two water molecules form the bridges between two V(IV) center ions. The presence of high spin V(IV) (I = 7/2) in the compound was verified by EPR measurements. In addition, decavanadate unit gave a shoulder at about 400 nm on the UV-Vis. spectrum of the compound. Moreover, at the FT-IR spectrum, the symmetric and asymmetric stretching vibrations of the bridging V–O–V units were observed. On the cyclic voltammogram of the compound, two reduction peaks (V(V)-V(IV) and V(IV)-V(II) reduction steps, respectively) at −1.03 and −1.35 V were observed at the cathodic scan; however, one oxidation peak (V(II)-V(III) oxidation step) at −1.22 V showed at the anodic scan. NMR results also support that the synthesized salt includes the coordinated water molecules and hydroxo groups.
Abstract: ABSTRACT Several studies examining vesicle fusion have been reported in last decades and have established a number of factors favoring the process of vesicle fusion. To determine whether variations to the physicochemical properties of the membrane affect the process of vesicle fusion, we worked with binary and ternary mixtures of large unilamellar vesicles (LUVs). The selected binary models were dioleoyl phosphocholine-cholesterol (DOPC-chol) and disteraroyl phosphocholine-cholesterol (DSPC-chol), and the tertiary mixtures were phosphatidylcholine-phsophatidylethanolamine-cholesterol (PC-PE-Chol); phosphatidylcholine-sphingomyelin-cholesterol (PC-SM-Chol); and phosphatidylcholine-phosphatidylserine-cholesterol (PC-PS-Chol). For all these models, the effect of cholesterol content on the lamella physicochemical properties was determined using 1,6-diphenyl-1,3,5-hexatriene (DPH) anisotropy, generalized polarization of 2-dimethylamino-6-lauroylnaphthalene (Laurdan), and DPH fluorescence lifetime. To determine whether fusion of these vesicles varied according to lipid composition, the % mixing content and the % leakage were determined. Examining membrane incorporation using fluorescence steady-state and time-resolved probe assays in the models indicated that cholesterol content affected packing order and lamellar hydration. In most of the models, nonmonotonic variations were observed for these parameters, and these variations could be interpreted as increases in the proportion of ordered microdomains. When the proportion of these domains is higher, the packing order increases, and the lamellar water decrease. Similarly, the % mixing, which was assessed as a fusion parameter, also exhibited nonmonotonic behavior, indicating that the fusion process is enhanced at these concentrations of cholesterol. However, DSPC vesicles do not merge, so more than the presence of microdomains is required to stabilize fusion.
Abstract: ABSTRACT A kinetical study about the Co electrodeposition onto Highly Oriented Pyrolytic Graphite electrodes from an aqueous solution containing 0.01 M CoCl2 + 1 M NH4CI (pH = 7) was conducted at overpotential conditions through potentiostatic studies. The entire chronoamperograms were adequately predicted, considering the contribution to the total current of three different processes: a Langmuir-type adsorption process, a three-dimensional nucleation and growth and a proton reduction process. In all cases, the nucleation rate and the number of active nucleation sites are potential dependent. The Atomic Force Microscopy study revealed the presence of homogeneous cobalt clusters of less of 100 nm in height and 50 nm in diameter at different potential values.
Abstract: ABSTRACT The development of new biomaterials has gained increasing attention in the last decade. One of the most important aspects in the development of these new materials is to understand the chemical cues presents in the native niche. Among all the techniques currently available for measuring those interactions, Raman spectroscopy offers a unique and non-invasive tool for exploring the behavior of the components within a given biomaterial and their surrounding microenvironment. This technique exploits the unique molecular vibrational fingerprints for pinpointing those interactions. The vibrational response can be improved to the single molecule level, in the presence of metal nanoparticles (NPs) with plasmonic properties (silver, gold and copper) in the so-called Surface-Enhanced Raman Scattering (SERS), which can be used for in-situ measurements. Another technique recently developed is the Shell-Isolated Nanoparticle-Enhanced Raman Spectroscopy (SHINERS), which overcomes signal contamination from chemical interactions between biomolecules and the metal surface; it does this by coating the metal surface with an inert layer of alumina or silica. In the present contribution, the role and the applications of Raman, SERS and related spectroscopic techniques in the study of biomolecules in biomaterials are reviewed and discussed.
Abstract: ABSTRACT The development of new biomaterials has gained increasing attention in the last decade. One of the most important aspects in the development of these new materials is to understand the chemical cues presents in the native niche. Among all the techniques currently available for measuring those interactions, Raman spectroscopy offers a unique and non-invasive tool for exploring the behavior of the components within a given biomaterial and their surrounding microenvironment. This technique exploits the unique molecular vibrational fingerprints for pinpointing those interactions. The vibrational response can be improved to the single molecule level, in the presence of metal nanoparticles (NPs) with plasmonic properties (silver, gold and copper) in the so-called Surface-Enhanced Raman Scattering (SERS), which can be used for in-situ measurements. Another technique recently developed is the Shell-Isolated Nanoparticle-Enhanced Raman Spectroscopy (SHINERS), which overcomes signal contamination from chemical interactions between biomolecules and the metal surface; it does this by coating the metal surface with an inert layer of alumina or silica. In the present contribution, the role and the applications of Raman, SERS and related spectroscopic techniques in the study of biomolecules in biomaterials are reviewed and discussed.
Abstract: ABSTRACT In this study, we examined the synthesis, and characterization of TiO2/poly(N-maleoylglycine-co-acrylic acid) (TiO2/poly(MG-co-AA)) nanocomposite. The nanocomposite was prepared by the dispersion of TiO2 nanotubes in a water solution of the polymer (3% w/w) and then it was lyophilized. The nanocomposite was characterized by FTIR and Raman spectroscopies. The incorporation of TiO2 nanotubes to the polymeric matrix was determined by transmission electron microscopy (TEM) from which TiO2 nanotubes in the inner of copolymer with diameters ranging between 90 and 100 nm were observed. The overall morphology of the previously synthetized nanotubes was determined by scanning electron microscopy (SEM). For the nanocomposite system, the morphology was studied by atomic force microscopy (AFM) from which a grain shape structure was observed. This process resulted in a new nanocompsite material with an average grain diameter estimated by SEM and AFM ranging between 210-240 nm. It was observed that the nanotubes were homogeneously dispersed within the polymeric matrix. The prepared material could be suitable in the design of electronic devices and additionally could have potential applications as biomaterial.
Abstract: ABSTRACT Four acceptor-donor organic conjugated molecules based on thieno[3,4-b]pyrazine-terthienyls were analyzed in order to explore the effect of the donor substituent on their molecular structures, electronic and optical properties. Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TD/DFT) calculations were carried out employing the B3LYP hybrid functional in combination with the 6-31G(d,p) basis set. The results suggests that the addition of electron-donating substituents to the conjugated molecules can diminish their energy gap value, which is beneficial to the photon harvesting. The lowest-lying absorption spectra of compounds substituted with electron donor groups exhibited a red-shift and a high oscillation factor compared with the unsubstituted molecule. Additionally, the ionization potential (IP), electron affinity (EA), reorganization energy (λ) and open-circuit voltage (Voc) of the molecules were evaluated. According to these values, the molecules show good photovoltaic properties, and efficient charge transfer for hole and electron and balanced charges.
Abstract: ABSTRACT This work is focused on the removal of Cr(VI) ions from aqueous solution using water-soluble poly(diallyldimethylammonium chloride), PDDA, coupled to an ultrafiltration membrane of regenerated cellulose and subsequent electrochemical reduction of Cr(VI) to Cr(III). The removal of Cr(VI), using the washing mode, was studied as a function of pH, the molar ratio of polymer:Cr(VI), and the presence of interfering ions. The enrichment mode was used to determine the maximum retention capacity of the polymer, and the release of Cr(VI) and regeneration of the polymer were analysed by sorption-desorption process. Subsequently, the electroanalysis of Cr(VI) was conducted by linear sweep voltammetry and full electrolysis at controlled-potential in acidic media and in the presence of PDDA. The results show an efficient removal of Cr(VI) (95%, 30 mg/L in the feed) using PDDA at pH 9 and a polymer:Cr molar ratio of 20:1. The retention capacity of the polymer was decreased by the presence of sulphate anions. The maximum retention capacity of PDDA was 33 mg Cr/g polymer at pH 9. Using the sorption–desorption process, the results indicated that this water-soluble polymer can release Cr(VI) and be regenerated. Finally, the electrolysis of Cr(VI) to Cr(III) was performed successfully in the presence of PDDA.
Abstract: ABSTRACT Studies on the bioavailability of As, of impacted vegetables; and As bioaccesibility in the edible parts of carrots (daucus carota), beets (beta vulgaris) and quinoa (chenopodium) growing in polluted soils thought “in vitro” gastrointestinal process; the As speciation both in the edible parts of vegetables and in their gastrointestinal extracts have been performed. Elemental analysis and As speciation have been performed by ICP-MS and LC-ICP-MS, respectively. The Arsenic recovery after the in vitro gastrointestinal digestion was from 98, 90 and 40% for carrots, beets and quinoa, respectively; with no significant transformation of original As species. These studies provide a clearer understanding of the impact that As and other contaminant elements may present in the population of this high polluted Chilean region.
Abstract: ABSTRACT The structure of this mulinolic acid consists of a mulinane skeleton and the corresponding isopropyl, methyl, carboxyl and methyl groups at C3, C8, C5, C13, respectively, which are β-oriented, whereas the hydroxyl group at C13 is α-oriented. The cyclopentane (A), ciclohexane (B) and cicloheptene (C) rings are trans (A/B) and (B/C) cis fused, and in an envelope, chair, and twist conformation respectively. In the crystal the molecules are linked by two intermolecular O—H⋅⋅⋅O hydrogen bond forming bidimensional supramolecular structures with graph-set notation R44(12), R44(40), R66(46) and C44(46). The absolute configuration of the title compound has been determined from the refinement of the Flack parameter16. On this basis the absolute configuration was assigned as C3R, C5S, C8S, C9S, C10S and C13R.
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