Estudo eletroanalítico do herbicida paraquat em soluções aquosas por voltametria de onda quadrada utilizando ultramicroeletrodos

The electrochemical behavior of paraquat on Pt, Au and carbon fiber ultramicroelectrodes were studied in laboratory samples by square wave voltammetry at high frequencies. The results showed two reversible peaks for paraquat reduction, in agreement to the literature data. The first peak was associated to the reduction of paraquat molecule in solution, with the further adsorption of the intermediate on the electrode surface. This adsorbed species undergoes to electroreduction in a reaction associated to the second voltammetric peak. The variation in pH and square wave parameters showed the best conditions to reduce paraquat as pH 5.0, frequency as high as 1000 s-1, scan increment of 2 mV and square wave amplitude of 50 mV. At such conditions, a variation of paraquat concentrations from 4.3 x 10-6 to 1.66 x 10-4 mol L-1 presented values for the detection limit equal to 3.9, 6.2 and 20.3 ppb on Pt, Au and carbon, respectively, at 1000 s-1. These values are quite below17 the allowed limit of paraquat in drinking water.

Método para a determinação de hexazinone e tebutiuron em água

This work presents an alternative method for determination of the herbicides tebuthiuron and hexazinone in ground water. The extraction was made with dichloromethane and the analyses by high performance liquid chromatography (HPLC), using reversed-phase column, C-18, mobile phase methanol/water 50:50, v/v, detection and quantification at 247 nm. The following validation parameters were obtained: limit of detection of method 0.02 and 0.03 µg L-1, limit of quantification of method 0.07 and 0.09 µg L-1; linear range limit of quantification of instrument - 300 µg L-1 (r² > 0.998); recoveries from 90.3 to 108.2% and 90.3 to 101.6%; intermediary precision (%RSD) < 8 and < 6%, for hexazinone and tebuthiuron, respectively. The method showed to be efficient and reliable for determination of the herbicides in ground water.

On the application of knoevenagel condensation for the synthesis of benzylidene benzothiazine compounds and structural study

The synthesis and physico-chemical properties of new 6-acetylamino or 6-benzoyl-amino 2-benzylidene-4-methyl-4H-benzo[1,4]thiazin-3-ones and 6-benzoylamino or 6-nitro 2-benzylidene-4H-benzo[1,4]thiazin-3-ones are described. These benzylidene benzothiazine compounds were prepared by the Knoevenagel condensation with benzaldehydes. The configurations and conformations of benzylidene benzothiazine derivatives were optimised using the semi-empirical method AM1.

Some pneumococcal serotypes are more frequently associated with relapses of acute exacerbations in COPD patients

Objectives: To analyze the role of the capsular type in pneumococci causing relapse and reinfection episodes of acute exacerbation in COPD patients. Methods: A total of 79 patients with 116 recurrent episodes of acute exacerbations caused by S. pneumoniae were included into this study (1995–2010). A relapse episode was considered when two consecutive episodes were caused by the same strain (identical serotype and genotype); otherwise it was considered reinfection. Antimicrobial susceptibility testing (microdilution), serotyping (PCR, Quellung) and molecular typing (PFGE/MLST) were performed. Results: Among 116 recurrent episodes, 81 (69.8%) were reinfections, caused by the acquisition of a new pneumococcus,and 35 (30.2%) were relapses, caused by a pre-existing strain. Four serotypes (9V, 19F, 15A and 11A) caused the majority (60.0%) of relapses. When serotypes causing relapses and reinfection were compared, only two serotypes were associatedwith relapses: 9V (OR 8.0; 95% CI, 1.34–85.59) and 19F (OR 16.1; 95% CI, 1.84–767.20). Pneumococci isolated from relapses were more resistant to antimicrobials than those isolated from the reinfection episodes: penicillin (74.3% vs. 34.6%, p,0.001), ciprofloxacin (25.7% vs. 9.9%, p,0.027), levofloxacin (22.9% vs. 7.4%, p = 0.029), and co-trimoxazole (54.3% vs. 25.9%, p,0.001). Conclusions: Although the acquisition of a new S. pneumoniae strain was the most frequent cause of recurrences, a third ofthe recurrent episodes were caused by a pre-existing strain. These relapse episodes were mainly caused by serotypes 9V and 19F, suggesting an important role for capsular type

Vid frågornas port

Soitinnus: sekakuoro. (SATB)

A Midsummer Night's Dream

Digitoitu 5. 9. 2008.

Detailed crystallization study of co-precipitated Y1.47Gd1.53Fe5O12 and relevant magnetic properties

The crystallization process of co-precipitated Y1.5Gd1.5Fe5O12 powder heated up to 1000 ºC at rate of 5 °C min-1 was investigated. Above 810 ºC crystalline Y1.47Gd1.53Fe5O12 was obtained with a lattice parameter of 12.41 Å and a theoretical density of 5.84 g cm-3. Dry pressed rings were sintered at 1270 and 1320 ºC, increasing the grain-size from 3.1 to 6.5 µm, the theoretical density by 87.6 to 95.3% and decreasing Hc from 2.9725 to 1.4005 Oe. Additionally, Hc increased when the frequency of the hysteresis graph varied from 60 Hz to 10 kHz, the curie temperature was 282.4 ºC and Ms equalled 9.25 emu g-1 (0.17 kG) agreeing well with the Bs-value of the hysteresis graph and literature values.

Purificação e caracterização de uma gentioexaose obtida de botriosferana por hidrólise ácida parcial

A hexa-oligosaccharide was obtained by partial acid hydrolysis from botryosphaeran, an exopolysaccharide (EPS) ^6;(1→3; 1→6)-D-glucan type, produced by the ascomyceteous fungus Botryosphaeria rhodina. The oligosaccharide was purified by gel filtration and charcoal-Celite column chromatography and the analysis was followed by HPAEC/PAD. The structure was determined by NMR spectroscopy and mass spectrometry, which showed that the oligosaccharide consists of six ^6;-D-glucopiranosyl units O-6 substituted (gentiohexaose).

Caracterização da pureza de fosfatidilcolina da soja através de RMN de ¹H e de 31P

A strategy is proposed to evaluate the purity of phosphatidylcholine from soybean lecithin, obtained by extraction or column chromatography, using the integrals ratio of ¹H NMR spectra. Integrals of methylene signals, around 1.3 and 1.6 ppm, are added and divided by the integral of the choline methyl groups, around 3.3 ppm. Before purification, a ratio of 19.68±1.37 was determined. Using extraction, a ratio of 10.70±0.61 was found, while from column chromatography, a value of 2.99±0.25 was detected. 31P NMR of standard phosphatidylcholine showed signals at -0.2 and -0.9 ppm, whereas the purified one showed a single signal at -0.9 ppm.

Constituintes químicos do caule de Senna reticulata Willd. (Leguminoseae): Chemical constituents isolated from the wood of Senna reticulata Willd.

The phytochemical investigation of the wood extracts of Senna reticulata (Leguminoseae) yielded six anthraquinones: chrysophanol, physcion, aloe-emodin, 1,3,8-trihydroxyanthraquinone, 3-methoxy-1,6,8-trihydroxyanthraquinone, emodin and the chrysophanol-10,10' bianthrone. The triterpenes a and b-amirin, the steroids b-sitosterol and stigmasterol as well as the flavonoid kaempferol were also identified. The structures were established by spectral analysis, including two-dimensional NMR techniques. It is the first report of 1,3,8-trihydroxyanthraquinone and 3-methoxy-1,6,8-trihydroxyanthraquinone in higher plants.

Constituintes químicos de Parmotrema lichexanthonicum Eliasaro & Adler: isolamento, modificações estruturais e avaliação das atividades antibiótica e citotóxica

From the lichen Parmotrema lichexantonicum were isolated the depsidone salazinic acid, the xanthone lichexanthone, and the depside atranorin. The two major compounds, salazinic acid and lichexanthone, were selected for structure modifications. Salazinic acid afforded O-alkyl salazinic acids, some of them potentially cytotoxic against tumor cell lines (HCT-8, SF-295 and MDA/ MB - 435). From lichexanthone were obtained norlichexanthone, 3-O-methylnorlichexanthone, 3-O-methyl-6-O-prenylnorlichexanthone, 3,6-di-O-prenyl-norlichexanthone, 3,6-bis[(3,3-dimethyloxyran-2-il)methoxy]-1-hydroxy-8-methyl-9H-xanten-9-one and 3,6-bis[3-(dimethylamine)propoxy]-1-hydroxy-8-methyl-9H-xanten-9-one. The last compound was the most active against S. aureus.

Evaluation of anti-Mycobacterium tuberculosis activity of Campomanesia adamantium (Myrtaceae)

The anti-Mycobacterium tuberculosis activity of Campomanesia adamantium fruits extracts were evaluated. Six compounds, identified as flavanones and chalcones were quantified by HPLC-DAD-UV. Promising antitubercular activity was observed with ethyl acetate extract (MIC 62.5 µg/mL) and their fractions (MIC values ranging from 39 to above 250 µg/mL). The better MIC result of 39 µg/mL was associated with two fractions that contain bigger amounts of 5,7-dihydroxy-6, 8-di-C-methylflavanone and 2',4'-dihydroxy-3',5'-dimethyl-6'-methoxychalcone. These compounds exhibited MICs >250 and 62.5 µg/mL, respectively, while their mixtures showed values ranging from 62.5 to 7.8 µg/mL, demonstrating a synergism between them.

Synthesis of resorcinolic lipids bearing structural similarities to cytosporone A

Inspired by the structure and biological activities of resorcinolic lipids and, particularly cytosporone A- a potent inhibitor of plantule germination and growth, we have performed the synthesis of the analogs 3-heptyl-3-hydroxy-5,7-dimethoxy-2-benzofuran-1(3H)-one (1) and 3-heptyl-3-hydroxy-4,6-dimethoxy-2-benzofuran-1(3H)-one (2). The intermediates and products were submitted to allelopathic test using Lactuca sativa L. seeds. Target compound 1 showed an inhibitory effect on germination and growth of hypocotyl and radicle in milimolar range.

Efficient synthesis of benzothiazine and acrylamide compounds

This article describes the synthesis of the new (2Z)-2-(4-methoxybenzylidene)-6-nitro-4H -benzo[1,4]thiazin-3-one, (2Z)-2-(4-methoxybenzylidene)-4-methyl-6-nitro-4H-benzo[1,4]thiazin-3-one, (2Z)-6-amino-2-(4-methoxybenzylidene)-4H -benzo[1,4]thiazin-3-one, (2Z)-6-butylamino-2-(4-methoxybenzylidene)-4-methyl-4H-benzo[1,4]-thiazin-3-one and (2E)-N-alkyl-N-(2-hydroxy-5-nitrophenyl)-3-phenylacrylamides and the spectroscopic data. The arylidenebenzothiazine compounds were prepared using the Knoevenagel condensation with substituted benzaldehydes in the presence of sodium methoxide in DMF. The presence of a nitro substituent in the 4-position, water and a slightly acid reaction medium in this condensation caused the rupture of the benzothiazine ring and subsequent formation of the phenylacrylamide compounds. A crystallographic data was presented for (2E)-3-(4-bromophenyl)-N-dodecyl-N -(2-hydroxy-5-nitrophenyl) acrylamide.

Poluição e a densidade de vegetação: BTEX em algumas áreas públicas de Curitiba - PR, Brasil

The occurrence of benzene, toluene, ethylbenzene, and xylenes (BTEX) in some public areas of Curitiba-PR, Brazil, was evaluated. Their concentrations were then related to the vegetation's density in each area. Average benzene concentrations varied from 3.9 to 6.1 _6;g m-3, with higher values occurring in poorly dense vegetation areas. For toluene, average concentrations ranged from 6.5 to 7.2 _6;g m-3. The effect of such pollutants was evaluated by means of a bio indicator, Tillandsia stricta. Variation in total chlorophyll content and in stomatic density were detected in some samples and may be related to the BTEX concentrations found in the studied areas.