Predição da demanda química de oxigênio em chorume maduro contendo reagente de Fenton, por meio de modelo matemático empírico gerado com planejamento fatorial completo

COD is an important parameter to estimate the concentration of organic contaminants. The closed system technique with the use of K2Cr2O7 is the most important one, however, it has the inconvenience to suffer positive chemical interferences from inorganic compounds such as Fe2+ and H2O2 (not enough reported in the literature). This paper considers a statistical-experimental set capable to validate a empirical mathematical model generated from a 23 experimental design, in the presence of Fe2+ and H2O2. The t test shows that mathematical model has 99,99999% confidence degree and the experimental validation test indicates absolute mean error of 4,70%.

Parâmetros bioquímicos foliares das espécies Licania tomentosa (Benth.) e Bauhinia forficata (Link.) para avaliação da qualidade do ar

Foliar analysis of biochemical parameters were carried out in order to investigate the influence of air pollutants on two tropical tree species (Licania tomentosa (Benth.) and Bauhinia forfícata (Link.)). Special attention was given to tropospheric ozone due to the fact that concentration levels in the region were found to be up to 140 µg m-3 for a 4 h average time, which is well above the value that can cause injuries to orchides and tobacco (59 µg m-3). Other pollutants such as nitrogen and sulphur oxides were measured and their ambient concentrations were also associated to biochemical alterations in the investigated species.

Caracterização do mel produzido por espécies de Melipona Illiger, 1806 (apidae: meliponini) da região nordeste do Brasil: 1. Características físico-químicas

Thirty three honey samples produced by four Melipona species from different areas of the State of Bahia, were analyzed with the aim to determine their physico-chemical characteristics, contributing to the establishment of standards for quality control. The majority of the average values for physico-chemical parameters fulfilled the quality criteria established by the Brazilian and international Legislations for Apis honey, except for moisture content, which afforded higher values. Concerning the high number of samples wich did not fit the limits for reducing sugars, it is necessary to define minimum values in order to characterize Melipona honeys, as well as criteria for use of diastasic activity.

Efeitos de agentes oxidantes e oxigênio dissolvido na descoloração do azo corante acid orange 7 por fotólise e fotocatálise

The decolorization of acid orange 7 azo dye by photolysis and photocatalysis by ZnO was investigated in the presence of oxidants such as NaClO3, NaBrO3, NaIO4, and K2S2O8 in an open reactor at 30 ºC. The decolorization was relatively fast at lower oxidants concentrations and slow rate at larger concentrations, except for persulfate in the photocatalysis. Concerning photolysis the rate constant enhanced gradually, except for chlorate, outreaching the obtained values by photocatalysis, at higher concentrations. The air saturation decreased the rate constant in both processes and indicated that the azo dye can be decolorized without dissolved oxygen in persulfate medium.

Degradação de espécies nitroaromáticas e remediação de efluentes da indústria de explosivos, utilizando-se processos redutivos-oxidativos fundamentados no uso de ferro metálico

In this work the potentiality of reductive-oxidative processes based on zero-valent iron was studied aiming the degradation of nitroaromatic compounds and the remediation of residues from the explosive industry. The reductive process was applied as a continuous treatment system, using steel-wool as zero-valent iron source. The process permitted an almost total degradation of nitrobenzene, nitrophenol, nitrotoluene, dinitrotoluene and trinitrotoluene, probably with generation of the respective amine-derivative. The yellow-water residue, containing soluble trinitrotoluene, was notably modified by the reductive process, a fact that permitted a substantial enhancement of its biodegradability. Furthermore, the subsequent photo-Fenton process allowed TOC removal of about 80%.

Composição química de óleos essenciais de espécies de Aniba e Licaria e suas atividades antioxidante e antiagregante plaquetária

Leaves and stems from Aniba panurensis (Meisn.) Mez, Aniba rosaeodora Ducke and Licaria martiniana (Mez) Kosterm. were collected in the Reserva Florestal Adolpho Ducke-AM and their essential oils were obtained by hydrodistillation procedures. The oils were analyzed by GC-FID and GC-MS resulting on fifty and six compounds being identified. The major components were linalool in A. rosaeodora, and β-caryophyllene in A. panurensis and L. martiniana. At qualitative assays the oils showed antioxidant and antiplatelet activities, but only weak activities were found at quantitative spectrometric assays.

Hidróxidos duplos lamelares: nanopartículas inorgânicas para armazenamento e liberação de espécies de interesse biológico e terapêutico

Studies about the inorganic nanoparticles applying for non-viral release of biological and therapeutic species have been intensified nowadays. This work reviews the preparation strategies and application of layered double hydroxides (LDH) as carriers for storing, carrying and control delivery of intercalated species as drugs and DNA for gene therapy. LDH show low toxicity, biocompatibility, high anion exchange capacity, surface sites for functionalization, and a suitable equilibrium between chemical stability and biodegradability. LDH can increase the intercalated species stability and promote its sub-cellular uptake for biomedical purposes. Concerning the healthy field, LDH have been evaluated for clinical diagnosis as a biosensor component.

Reaproveitamento de óxidos de manganês de pilhas descartadas para eletrocatálise da reação de redução de oxigênio em meio básico

The oxygen reduction reaction was studied in alkaline media using manganese oxides obtained from spent batteries as electrocatalysts. Three processes were used to recover manganese oxides from spent batteries. The particles obtained were in the range from 8 to 11 nm. The electrochemical experiments indicated a good electrocatalytic activity toward oxygen reduction using the different samples and showing approximately a direct transference of 4 electrons during the process. Even though all the processes were efficient, the best result was observed for the prepared sample using reactants of low cost.

Espécies tropicais de pteridófitas em associação com fungos micorrízicos arbusculares em solo contaminado com arsênio

The symbiosis of plants with mycorrhizal fungi represents an alternative to be considered during the processes of revegetation and rehabilitation of arsenic-contaminated soil. The aim of this study was to evaluate under greenhouse conditions the effect of arsenic on the mycorrhizal association of two species of tropical fern (Thelypteris salzmannii and Dicranopteris flexuosa). T. salzmannii had higher rates of colonization and higher density of spores while D. flexuosa showed greater sensitivity to smaller concentrations of arsenic and association with mycorrhizal fungi. Our results indicate that screening and selection of mycorrhizal fungal isolates/species is possible and effective for phytoremediation of arsenic-contaminated soils.

Constituintes fenólicos e atividade antioxidante da geoprópolis de duas espécies de abelhas sem ferrão amazônicas

We investigated the phenolic constituents and antioxidant activity of geopropolis from two species of stingless Amazonian bees, Melipona interrupta and Melipona seminigra. The chemical investigation of geopropolis from Melipona interrupta led to the isolation of 5,7,4'-trihydroxyflavonone, 3,5,6,7,4'-pentahydroxyflavonol, naringenine-4'-O-b-D-glucopyranoside and myricetin-3-O-b-D-glucopyranoside. Their structures were assigned based on spectroscopic analyses, including two-dimensional NMR techniques. Antioxidant activity of methanol and ethanol extracts of M. interrupta and M. seminigra were measured using the 1,2-diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging assay. This is also the first work reporting the chemical investigation of stingless bee species from the Amazonian region.

Efeitos energético-estruturais em compostos heteropolicíclicos com oxigénio ou enxofre

The present article involves a comparative study of the influence of oxygen or sulfur heteroatoms present in the central ring of polycyclic compounds, in order to clarify the correlation between the respective thermophysical or thermochemical properties and structural characteristics. Considering the importance of these types of compounds for their broad spectrum of application in diverse fields, from pharmacology to the development of new materials, the critical interpretation of such properties for their crucial role in the reactivity of these substances is of great interest. Knowledge on these thermodynamic data for key compounds is also relevant to the prediction and understanding of the properties and behavior of other parent compounds.

Análise espacial e quimiométrica da distribuição de espécies metálicas em solos alagáveis e não alagáveis da Bacia do Médio Rio Negro, Amazônia

This study used chemometric tools and a Geographic Information System (GIS) to determine the influence of organic matter and anthropogenic activity on the distribution of metal species between two major communities of the Middle Negro River Basin-AM. Higher concentrations of metal species were determined in flooded regions. The chemometric analysis showed the affinity of organic matter for potentially toxic metals, indicating its selectivity. GIS spatial analysis has shown that proximity to urban areas is a variable that is likely to influence the pattern of concentration of organic matter, and consequently the distribution of metal species between flooded and non-flooded areas.

SISTEMAS ALTERNATIVOS DE CALIBRAÇÃO PARA DETERMINAÇÃO ESPECTROFOTOMÉTRICA SIMULTÂNEA DE ESPÉCIES COM INTERFERÊNCIA ESPECTRAL

Two simple and efficient procedures have been developed for the rapid simultaneous determination of compounds with mutual spectral interference (rifampicin (RIF) and isoniazid (INH)). The first method was based on the UV–Vis spectral signal (190–600 nm) of synthetic RIF and INH aqueous solutions, whereas the second method involved the visible spectral signal registered between 350 and 800 nm after the reaction of INH with a Cu2+/neocuproine complex. Both multivariate spectrophotometric methods show excellent prevision capacity, providing results that are statistically equivalent with those provided by the standard chromatographic procedure. The methods were validated according to criteria established by ANVISA, showing precision, accuracy and robustness compatible with the requirements for new analytical methods, additionally allowing the reduction of waste generation.

REDUÇÃO DE VARIÁVEIS DE ENTRADA DE REDES NEURAIS ARTIFICIAIS A PARTIR DE DADOS DE ANÁLISE DE COMPONENTES PRINCIPAIS NA MODELAGEM DE OXIGÊNIO DISSOLVIDO

The objective of this work is to demonstrate the efficient utilization of the Principal Components Analysis (PCA) as a method to pre-process the original multivariate data, that is rewrite in a new matrix with principal components sorted by it's accumulated variance. The Artificial Neural Network (ANN) with backpropagation algorithm is trained, using this pre-processed data set derived from the PCA method, representing 90.02% of accumulated variance of the original data, as input. The training goal is modeling Dissolved Oxygen using information of other physical and chemical parameters. The water samples used in the experiments are gathered from the Paraíba do Sul River in São Paulo State, Brazil. The smallest Mean Square Errors (MSE) is used to compare the results of the different architectures and choose the best. The utilization of this method allowed the reduction of more than 20% of the input data, which contributed directly for the shorting time and computational effort in the ANN training.

Identificação sorológica de espécies de vírus que infetam cucurbitáceas em áreas produtoras do Maranhão

Os vírus representam sérios obstáculos para o sucesso da olericultura no mundo inteiro, constituindo a identificação daqueles de maior incidência numa região, papel fundamental para o estabelecimento de estratégias de controle. Visitas de campo foram realizadas a plantios de espécies de cucurbitáceas em áreas produtoras do Maranhão e amostras foliares foram coletadas de 118 plantas com sintomas ou suspeita de sintomas de vírus, sendo 46 de abóbora (Cucurbita moschata), 30 de melancia (Citrullus lanatus), 23 de maxixe (Cucumis anguria), 13 de pepino (C. sativus) e seis de melão (C. melo). Todas as amostras foram testadas contra anti-soros específicos para os principais vírus das famílias Bromoviridae, Comoviridae e Potyviridae que infetam cucurbitáceas no Nordeste, mediante "enzyme-linked immunosorbent assay" (ELISA) indireto e dupla difusão em agar. Os resultados revelaram a identificação sorológica de Papaya ringspot vírus (PRSV) em 64,4% das amostras analisadas, seguido de Watermelon mosaic virus-2 (WMV-2) em 15,2%, Cucumber mosaic virus (CMV) em 6,8%, Squash mosaic virus (SqMV) em 3,4% e Zucchini yellow mosaic virus (ZYMV) em 3,4%. Este levantamento confirma a predominância do PRSV em espécies de cucurbitáceas cultivadas no estado do Maranhão.