Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

In this paper, the zinc carbonate hydroxide (Zn5(OH) 6(CO2)2, ZCHO) was prepared by a facile hydrothermal method assisted chitosan (CS). The as-prepared product was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TG). Results indicated that every micro-sized ZCHO particle had a multi-layered structure and was composed of many ZCHO nanoplates. The used CS played the role of the template in the formation of well multi-layered ZCHO particles. TG measurements had further indicated that the remained content of CS in the as-prepared ZCHO powders was about 8 Wt.%. The adsorption isotherm results showed that the ZCHO powders with CS exhibited massive removal of Cu2+ from aqueous solution at room temperature. The equilibrium adsorption was well described by the Freundlich isotherm model. Based on the above experimental results, the possible removal mechanism of Cu2+ by the multi-layered ZCHO was proposed.

The graphene-modified glassy carbon electrode (Gr/GCE) was fabricated by casting graphene (Gr). Some electrochemical parameters for diethylstilbestrol (DES) detection, such as pH, scan rate, and accumulation time were discussed. The interaction of DES with DNA at a Gr/GCE was studied by electrochemical method and factors influencing the interaction were optimized. Under the optimized conditions, the results revealed that the peak current decreased and the peak potential shifted to the positive side after adding DNA into the solution containing DES. We deduced that the interaction of DES with DNA mainly is intercalation. The interaction of DES with DNA was studied by ultraviolet and visible (UV-Vis) absorption spectroscopy. Also, with the addition of DNA, hyperchromic effect and small red shifts were observed in its UV-VIS spectra upon addition of DNA, results indicated that the DES molecule intercalated into the DNA, and the complex of DES-DNA was formed.

Trifluoroacetic acid was applied as an efficient catalyst for the one-pot four-component synthesis of N-aryl/alkyl-3-aminodihydropyrrol-2-one-4-carboxylates via the domino reaction of amines, formaldehyde and dialkyl acetylenedicarboxylates at ambient temperature in methanol. This methodology includes number of advantages such as: short reaction time, clean work-up, use of inexpensive catalyst, high yields and clean work-up. The work-up of this reaction involves only a filtration and a simple washing step with MeOH, and there is no need for column chromatography.

In this manuscript, thermal and kinetic features of a tannic acid was studied by simultaneous TG-DTA techniques in the nitrogen atmosphere at four heating rate. It was observed that thermal decomposition of its constituents occurred in two steps. Model free isoconversional methods namely modified Coast-Redfern (CR), Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (FWO) and Freidman (FR) were used for revelation of decomposition kinetics (Ea and lnA) on the whole range of temperature. Mechanisms of decomposition process have been found to follow first order of decomposition rate. Reaction order does not have a substantial effect on the process because of the high value of pre-exponential factor. It was observed that, at the last stage of decomposition process, value of activation energy and pre-exponential factor increased. Decomposition of tannic acid was confirmed by IR spectroscopy.

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.

The paracetamol–water (PA–H2O) complexes formed by hydrogen bonding interactions were investigated at the MP2/6–311++G(d,p) level. Six PA–H2O complexes possessing various types of hydrogen bonds (H–bonds) were characterized by geometries, energies, vibrational frequencies. Natural bond orbital (NBO), quantum theory of atoms in molecules (QTAIM) and the localized molecular orbital energy decomposition analysis (LMO–EDA) were performed to explore the nature of the hydrogen–bonding interactions in these complexes. The intramolecular H–bond formed between the methylene and carbonyl oxygen atom of paracetamol is retained in most of complexes. The H–bonds in PW1 and PW6 are stronger than other H–bonds, moreover, the researches show that both the hydrogen bonding interaction and structural deformation play important roles for the relative stabilities of PA–H2O complexes.

In this paper, we present an approach and investigation on the evolution of the icosahedral and decagonal phases of quasicrystalline alloys Al62.2Cu25.3Fe12.5 E Al65Ni15Co20, the oxidation behavior in them. The quantification of the quasicrystalline and crystalline phases present in the quasicrystals provides important information in the mass transport by diffusion, as well as the phase transformations that occurred. For this purpose, X-ray diffraction (XRD) and Rietveld Method Quantification, Scanning Electron Microscopy (SEM) / Dispersive Energy Spectroscopy (EDS), Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis). The results showed structural aspects of the two compositions of quasicrystals, these were elaborated and obtained in an arc induction furnace. The oxidation of the alloy Al62.2Cu25.3Fe12.5 showed intermetallic phases with associations of the elements of the alloy and above 735 °C was observed that the crystalline phase is stable in the icosahedral phase. The quasicrystals Al65Ni15Co20, with the interaction of oxygen, happens in the surface of symmetry 10 times plane perpendicular vector. The formation of a thin film of the aluminum oxide with a well ordered hexagonal shape structure, with a domain opposite the decagonal phase with lateral size at about 35 Å.

Starting from ibuprofen, a non-steroidal anti-inflammatory drug, N,N’-disubstituted thiourea derivatives were synthesized by refluxing the acid chloride of ibuprofen with potassium thiocyanate followed by substituted anilines to get N-2-(4-(2-methylpropyl)phenyl)propionoyl-N´-(2´-bromophenyl) thiourea (1), N-2- (4-(2-methylpropyl)phenyl)propionoyl-N´-(2´-chlorophenyl) thiourea (2) and N-2-(4-(2-methylpropyl)phenyl)propionoyl-N´-(3´,4´-dichlorophenyl) thiourea (3). Metal complexes (4-15) of (1-3) were synthesized by refluxing it with one equivalence salts of Co (ΙΙ), Ni(ΙΙ), Pb(ΙΙ) and Cu(Ι). Structures of all the synthesized thiourea ligands and their metal complexes were determined by FTIR and 1HNMR spectroscopy. Shift in stretching frequency in FTIR and resonance frequency in 1HNMR spectroscopic data suggested that the ligands and metal are coordinated to afford respective metal complexes M[L]n. The synthesized compounds were tested against urease enzyme and the results were compared with standard thiourea, as positive control. Most of the investigated compounds showed potential inhibitory activity against Jack bean urease. Compound 5 was found to be the most potent urease inhibitor with IC50 of 14.6 μM, whereas compounds 8, 11 and 12 possessed potent urease inhibition. The tested compounds can be taken as lead molecules for gastrointestinal ulcer therapy.

Entocid syrup is a balanced composition of vigilantly selected and formulated with effective herbs of proven efficacy in intestinal ailments covering the segment of hyper-acidity symptoms. Entocid is scientifically formulated in such a way that it not only neutralizes the acid secretion but at the same time it strengthens the stomach thus acts promptly and relieves the symptoms of GI upsets and in the long-run prevents the recurrence of such symptoms. The ingredients of Entocid syrup are rich in alkaloids, proteins, vitamins, glycosides, bioflavonoid and trace elements, formulated using ten potent herbal drugs namely Amomum sabulatum, Berberis aristata, Cinnamomum tamala, Coriandrum sativum, Cuminum cyminum, Foeniculum vulgare, Vitis vinifera, Mesua ferrea, Glycyrrhiza glabra and Mentha piperita. The flavonoid compounds exhibit preventive effects from colon carcinogenesis, lipid lowering effects, anti-oxidant, anti-inflammatory, anti-depressant and anti-atherogenic properties. To develop the assay method, high-performance liquid chromatography (HPLC) with a diode-array detector (DAD) was used. Using HPLC/DAD, catechin was eluted with gradient program. The UV characteristic of catechin, the detection wavelength was monitored at 265 nm. Method validation including limit of quantitation, the accuracy, inter and intra day and limitation was performed by using recovery tests. The future development of flavonoids-based drugs is limitation and assumes to provide significant effects on digestion related diseases.

This work describes the catalytic study of [(Cp*)Co(Ind)] (with Cp*= pentamethylcyclopentadienyl, Ind= Indenyl, (C9H7)) complex in cyclotrimerization of phenylacetylene. From the cylcotrimerization reaction was possible to obtain products such as substituted pyridines 2-methyl-3,5-diphenylpyridine (3), 2-methyl- 4,6-diphenylpyridine (4) and the compound 1,2,4-triphenylbenzene (5) using acetonitrile as solvent. On the other hand, using toluene as solvent under the same working conditions, the product of reaction was 1,3,5-triphenylbenzene (1). Furthermore, by varying the working conditions, the reaction is 90% selective towards the formation of pyridines. In addition, has been appreciated the formation of another product 1,4-diphenilbuta-1,3-diyne (2), which was isolated and characterized by means NMR and GC-Mass spectrometry.