[en] Cr(VI) in low concentrations is reduced at room temperature by either concentrated perchloric acid or 1M perchloric acid to produce Cr³⁺, CrCl²⁺ and CrCl⁺₂. (Author)

[en] In this work, it was studied the behavior of the nonionic surfactant aqueous solutions, containing or not a hydrotropic agent, by resonance magnetic nuclear (NMR). We have studied monofunctional diblock copolymers of poly (propylene oxide-ethylene oxide) (R-PPO-PEO-OH, where R length is linear C₄) as nonionic surfactant and sodium p-toluenesulfonate (Na-PTS) as hydrotropic agent. The critical micelle concentration (CMC) of the aqueous copolymers solution was obtained from ¹H-NMR. The primary study of the interaction between the copolymer, under the unimer and micelle forms, and the hydrotrope, in aqueous solutions, was evaluated by ¹H-NMR and ¹³ C-NMR. (author)

[en] A spectrometer of non-sophisticated construction for ultra weak emission measurements is described. (Author)

[en] Simple and sensitive procedures for the extraction/preconcentration of molybdenum based on vortex-assisted solidified floating organic drop microextraction (VA-SFODME) and cloud point combined with flame absorption atomic spectrometry (FAAS) and discrete nebulization were developed. The influence of the discrete nebulization on the sensitivity of the molybdenum preconcentration processes was studied. An injection volume of 200 μ resulted in a lower relative standard deviation with both preconcentration procedures. Enrichment factors of 31 and 67 and limits of detection of 25 and 5 μ L^-1 were obtained for cloud point and VA-SFODME, respectively. The developed procedures were applied to the determination of Mo in mineral water and multivitamin samples. (author)

[en] This paper reports the synthesis of methanones and esters bearing different substitution patterns as spacer groups between aromatic rings. This series of compounds can be considered phenstatin analogs. Two of the newly synthesized compounds, 5a and 5c, strongly inhibited tubulin polymerization and the binding of [³H] colchicine to tubulin, suggesting that, akin to phenstatin and combretastatin A-4, they can bind to tubulin at the colchicine site. (author)

[en] Superparamagnetic iron oxide nanoparticles are suitable contrast agents for magnetic resonance imaging due to their effect on proton relaxation times, and excellent biocompatibility and biodistribution in tissue. In the present study, a ferrofluid formed by dextran coated iron oxide nanoparticles was prepared by the coprecipitation method and with subsequent steps of crosslinking and addition of functionalizations on the nanoparticle's surface (amino groups and a fluorophore). The effect of differences in the synthesis route (ratio of dextran to iron salts and temperature of the reaction) on the physico-chemical characteristics of the nanoparticles and their performance as contrast agents for magnetic resonance imaging was investigated. Overall, the nuclear magnetic relaxation times of water protons in aqueous suspensions of the nanoparticles did not show major differences among different batches, with no significant effect due to the addition of the fluorophore or changes in the dextran fraction of up to 50%. Larger reductions in the ratio of dextran to iron salts resulted in particles with slightly larger sizes, higher saturation magnetization and distinct nuclear magnetic relaxation times. (author)

[en] The chemical investigation of the stem EtOH extract of S. buddleifolium resulted in the isolation of terpenoids, amides, lignans and a steroidal alkaloid. Based on HRMS, IR and ¹H and ¹³C NMR data analysis, the structures of the isolated compounds were identified as: 13-hydroxysolavetivone, betulinic acid, N-trans-caffeoyltyramine, N-trans-feruloyldopamine, N-trans-p-cumaroyltyramine, N-trans-feruloyltyramine, N-trans-feruloyl- 3’-O-methoxydopamine, alangilignoside C, isolariciresinol, polistachiol, (+)-(8R,7’S,8’S)-3α-O-(β-D-glucopiranosyl)-lioniresinol, (-)-(8S,7’R,8’R)-3α-O-(β-D-glucopiranosyl)-lioniresinol and solamargine. The occurrence of terpenoids and amides is common in Solanum, unlike lignans which are rare. The isolated lignans described in this work are reported for the first time in the genus Solanum. (author)

[en] Nuclear magnetic resonance (NMR) is one of the most versatile analytical techniques for chemical, biochemical and medical applications. Despite this great success, NMR is seldom used as a tool in industrial applications. The first application of NMR in flowing samples was published in 1951. However, only in the last ten years Flow NMR has gained momentum and new and potential applications have been proposed. In this review we present the historical evolution of flow or online NMR spectroscopy and imaging, and current developments for use in the automation of industrial processes. (author)

[en] Phytochemical studies of the leaves and fruits have led to the identification of the known amides (E)-N-methyl-cinnamamide, N-benzoyltyramine, N-benzoyl-O-geranyl tyramine, N-benzoyl-O-(4-acetoxyl)-geranyl tyramine, in addition to the new N-{2-[4-(butoxyl-3-one)phenyl]ethyl}benzamide, N-{2-[4-(2,3-dihydroxy-2-methyl-butoxylanal)phenyl]ethyl}benzamide, N-{2-[4-(2,3-dihydroxy-2-methyl-butoxyloic) phenyl]ethyl}benzamide, N-benzoyl-O-(4-acetoxyl-6,7-epoxy)-geranyltyramine, N-benzoyl-O-(4-acetoxyl-6,7-dihydroxy)-geranyltyramine and N-benzoyl-O-(6-acetoxyl-4,7-dihydroxy)-geranyltyramine. The isolated compounds clearly point to Swinglea phytochemical affinities with other Aurantioideae species. (author)

[en] The importance of medicinal plants and their use in industrial applications is increasing worldwide, especially in Brazil. Phyllanthus species, popularly known as 'quebra-pedras' in Brazil, are used in folk medicine for treating urinary infections and renal calculus. This paper reports an authenticity study, based on herbal drugs from Phyllanthus species, involving commercial and authentic samples using spectroscopic techniques: FT-IR, ¹H HR-MAS NMR and ¹H NMR in solution, combined with chemometric analysis. The spectroscopic techniques evaluated, coupled with chemometric methods, have great potential in the investigation of complex matrices. Furthermore, several metabolites were identified by the NMR techniques. (author)