RESUMO
In this research, the adsorption of three synthetic dyes dissolved in an aqueous solution on chitosan cryogel beads (Q-C-EGDE) was compared. The effect of the pH of the solution on the adsorption capacity of each dyes was analyzed. Furthermore, the kinetics and adsorption isotherms were compared, at temperatures of 283.15 K, 303.15 K and 323.15 K, and the kinetic and adsorption equilibrium data were fitted to three mathematical models, respectively. The biosorbent was characterized by scanning electron microscopy (SEM), the nitrogen physisorption BET method and Fourier transform infrared spectroscopy (FTIR). The characterization results show that the cryogel is composed of low-surface, macroporous, porous grooved walls. The functional groups that took part in the adsorption were mainly amino groups (NH3+). When comparing the adsorption capacities, it was found that the dyes adsorb in the following order Blue 1 > Red 2 > Yellow 5 reaching capacities from 1600 mg/L to 850 mg/L. The results of the adsorption and mathematical modelling suggest that the process is regulated mainly by physisorption and is largely limited by mass transfer mechanisms within the cryogel, where the electrostatic charges present affect adsorption. The latter was corroborated by the Monte Carlo simulation.
Assuntos
Quitosana/química , Corantes/química , Criogéis/química , Adsorção/efeitos dos fármacos , Concentração de Íons de Hidrogênio , Cinética , Microscopia Eletrônica de Varredura/métodos , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Temperatura , Poluentes Químicos da Água/química , Purificação da Água/métodosRESUMO
The azo dyes, Yellow 5 (Y5), Red 2 (R2) and Blue 1 (B1), quantified in solutions and in mixtures of binary dyes, were studied by means of UV-Vis spectroscopy. In this work was used a CIE algorithm developed in Visual Basic for Applications (VBA). The CIE algorithm is based on the tristimulus chromaticity diagram, as an alternative to the shielding effect that arises in dye mixtures, and it can also be applied to complex quantification methods such as HPLC (High Performance Liquid Chromatography). The results obtained through of the algorithm, showed a higher accuracy from 97 to 99% in relation with similar UV-Vis quantification methods. In contrast, linear methods only managed to reach an accuracy from 78 to 98%. Additionally, the algorithm yielded significant similar values to the UHPLC reference method. The results showed that the method CIE algorithm was accessible and reliable to quantify binary mixtures of the dyes used which suggests the possibility to apply this method on other dyes, within the limits of quantification obtained in this study (0.076-24.56 mg/L) and the pH values from 2 to 10.
Assuntos
Compostos Azo/análise , Colorimetria/métodos , Colorimetria/normas , Espectrofotometria Ultravioleta/métodos , Espectrofotometria Ultravioleta/normas , Espectrofotometria/métodos , Espectrofotometria/normas , Algoritmos , Calibragem , Cromatografia Líquida de Alta Pressão , Limite de Detecção , Linguagens de ProgramaçãoRESUMO
Functional groups of the activated carbon play the major role in metals removal from aqueous solutions and, for this reason, different treatments can be used to modify the adsorbent surface improving the adsorption capacity for a particular pollutant. In this research, oxidation with nitric acid, heating under an inert atmosphere, and ammonia treatment were applied to modify the activated carbon surface. The modified adsorbents were used for the removal of hexavalent chromium (Cr(VI)) from aqueous solutions at different concentrations (10-500â¯mgâ¯L-1), pH 6, and 25⯰C. Adsorption mechanisms of Cr(VI) on the activated carbon were proposed based on the surface chemistry, adsorption/reduction, and desorption experiments. Findings demonstrate that acid functional groups of the activated carbon had an important effect on the hexavalent chromium removal. For instance, a high reduction of Cr(VI) to Cr(III) (50%) was obtained by the oxidized adsorbents, whereas the heat treated adsorbents achieved a low reduction (35%), but the ammonia-treated activated carbon achieved the lowest reduction (20%). The heat-treated adsorbent showed the best Cr(VI) adsorption capacity (48â¯mgâ¯g-1), especially at equilibrium Cr(VI) concentration lower than 200â¯mgâ¯L-1, and the fastest adsorption kinetics among the studied adsorbents. Furthermore, the highest Cr(VI) desorption (90%) was achieved with 0.1â¯N NaOH-NaCl solutions. In summary, an anionic/reduction coupled adsorption mechanism of Cr(VI) seems to be feasible, and the heat-treated activated carbon is an interesting option for sequestering Cr(VI) species from aqueous effluents.
Assuntos
Carvão Vegetal , Poluentes Químicos da Água , Adsorção , Cromo , Concentração de Íons de Hidrogênio , SoluçõesRESUMO
The concept of a 'proteomic constraint' proposes that the information content of the proteome exerts a selective pressure to reduce mutation rates, implying that larger proteomes produce a greater selective pressure to evolve or maintain DNA repair, resulting in a decrease in mutational load. Here, the distribution of 21 recombination repair genes was characterized across 900 bacterial genomes. Consistent with prediction, the presence of 17 genes correlated with proteome size. Intracellular bacteria were marked by a pervasive absence of recombination repair genes, consistent with their small proteome sizes, but also consistent with alternative explanations that reduced effective population size or lack of recombination may decrease selection pressure. However, when only non-intracellular bacteria were examined, the relationship between proteome size and gene presence was maintained. In addition, the more widely distributed (i.e. conserved) a gene, the smaller the average size of the proteomes from which it was absent. Together, these observations are consistent with the operation of a proteomic constraint on DNA repair. Lastly, a correlation between gene absence and genome AT content was shown, indicating a link between absence of DNA repair and elevated genome AT content.
Assuntos
Bactérias/genética , Reparo de DNA por Recombinação/genética , Proteínas de Bactérias/genética , Composição de Bases , Análise por Conglomerados , Enzimas Reparadoras do DNA/genética , Genoma Bacteriano , Modelos Genéticos , Proteoma/genéticaRESUMO
BACKGROUND: Hyperhomocysteinaemia is a factor related to the development of atherosclerosis in rheumatoid arthritis (RA). However, Hispanics with RA develop high rates of coronary disease; there are no studies about the frequency and factors related to high levels of homocysteine in Mexican patients. OBJECTIVE: To evaluate the prevalence and characteristics associated with hyperhomocysteinaemia in Mexican patients with RA. METHODS: One hundred and fifty-two patients with RA were compared with 153 controls. The assessment in RA included clinical characteristics, disease activity (RADAR), functioning (HAQ-Di and global functional status), comorbidity, and radiological damage. Laboratory determinations included total serum homocysteine (tHcy), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), rheumatoid factor (RF), and lipid profile. RESULTS: Median levels of homocysteine were higher in RA compared with controls (11.3 vs. 9.3, p<0.001). Twenty per cent of the patients with RA had hyperhomocysteinaemia (>15 micromol/L) compared with 6% in controls (p<0.001). There was statistical association between hyperhomocysteinaemia in RA with male gender (p<0.001), impairment in the global functional status (p = 0.004), higher radiological damage (p = 0.001), and CRP (p = 0.04). There was no association with RADAR, HAQ-Di, or RF, methotrexate dose or duration of use. In the adjusted multivariate model, the two variables associated with higher risk for hyperhomocysteinaemia were male gender (OR = 4.2, 95% CI 2 to 12, p = 0.006) and higher radiological damage (III-IV) (OR = 3.4, 95% CI 1.3 to 9, p = 0.01). CONCLUSIONS: Our data show a high prevalence of hyperhomocysteinaemia in Mexican patients with RA. More effort is required to evaluate and treat earlier this coronary risk factor.
Assuntos
Artrite Reumatoide/complicações , Homocisteína/sangue , Hiper-Homocisteinemia/epidemiologia , Adolescente , Adulto , Idoso , Artrite Reumatoide/sangue , Artrite Reumatoide/epidemiologia , Aterosclerose/epidemiologia , Aterosclerose/etiologia , Biomarcadores/sangue , Proteína C-Reativa/metabolismo , Colesterol/sangue , Feminino , Seguimentos , Humanos , Hiper-Homocisteinemia/sangue , Hiper-Homocisteinemia/complicações , Incidência , Masculino , México/epidemiologia , Pessoa de Meia-Idade , Estudos Retrospectivos , Fator Reumatoide/sangue , Fatores de Risco , Índice de Gravidade de DoençaRESUMO
BACKGROUND: Rat hind-foot carrageenan induced edema (CIE) is a widely used model to evaluate anti-inflammatory drugs. It shows two well-defined phases, however a third not fully characterized phase has been observed. Superoxide dismutase (SOD) is a free radical-scavenger with anti-inflammatory activity. In our country there is not a specifically designed instrument to evaluate edema in CIE. METHODS: Edema was induced by intraplantar injection of carraageenan. Fours groups were evaluated: placebo, two different doses of SOD, and Naproxen. Edema was evaluated by a specially designed mercury plethismograph. Intensity of the inflammatory reaction was determined during the classical early and late phases and during the third very late phase. RESULTS: All treatments, but higher dose of SOD, showed good anti-inflammatory activity throughout early, late, and very late phases. Naproxen was more effective than SOD during first and second phase, however this difference disappeared during the third phase. In terms of equimolar basis the enzyme appeared 1,800 time more potent than Naproxen. Mercury plethysmometer performance was fine. CONCLUSIONS: The anti-inflammatory activity of SOD and Naproxen is extended until the very late phase in the CIE model. In this bioassay, this long lasting activity of the enzyme should be ascribed to a mechanism supplementary to its free radical-scavenger property. SOD may be indeed an alternative treatment in inflammatory diseases.
Assuntos
Anti-Inflamatórios não Esteroides/uso terapêutico , Edema/tratamento farmacológico , Sequestradores de Radicais Livres/uso terapêutico , Naproxeno/uso terapêutico , Superóxido Dismutase/uso terapêutico , Animais , Carragenina/toxicidade , Edema/induzido quimicamente , Pletismografia , Ratos , Ratos Wistar , Reprodutibilidade dos TestesAssuntos
Emigrantes e Imigrantes , Etnicidade , Eugenia (Ciência) , Preconceito , Prática de Saúde Pública , Condições Sociais , Problemas Sociais , Distúrbios Civis/economia , Distúrbios Civis/etnologia , Distúrbios Civis/história , Distúrbios Civis/legislação & jurisprudência , Distúrbios Civis/psicologia , Cuba/etnologia , Coleta de Dados/história , Emigrantes e Imigrantes/educação , Emigrantes e Imigrantes/história , Emigrantes e Imigrantes/legislação & jurisprudência , Emigrantes e Imigrantes/psicologia , Etnicidade/educação , Etnicidade/etnologia , Etnicidade/história , Etnicidade/legislação & jurisprudência , Etnicidade/psicologia , Eugenia (Ciência)/história , Eugenia (Ciência)/legislação & jurisprudência , História do Século XX , Humanos , Informática em Saúde Pública/economia , Informática em Saúde Pública/educação , Informática em Saúde Pública/história , Informática em Saúde Pública/legislação & jurisprudência , Prática de Saúde Pública/economia , Prática de Saúde Pública/história , Prática de Saúde Pública/legislação & jurisprudência , Condições Sociais/economia , Condições Sociais/história , Condições Sociais/legislação & jurisprudência , Políticas de Controle Social/economia , Políticas de Controle Social/história , Políticas de Controle Social/legislação & jurisprudência , Problemas Sociais/economia , Problemas Sociais/etnologia , Problemas Sociais/história , Problemas Sociais/legislação & jurisprudência , Problemas Sociais/psicologia , Valores Sociais/etnologia , Migrantes/educação , Migrantes/história , Migrantes/legislação & jurisprudência , Migrantes/psicologiaRESUMO
Our goal is to study the work carried out by the Cuban naturalist Antonio Parra between 1790-1792, that didn't limit to the making of herbariums and to the shipment of plants and seeds to Spain with the purpose of acclimatizing them to the Peninsula, but rather he fathomed in the composition of a catalog and a discourse on the means to naturalize in Spain the trees of the Habana.