Produtos naturais para o controle da transmissão da dengue: atividade larvicida de Myroxylon balsamum (óleo vermelho) e de terpenóides e fenilpropanóides

The bioassay-guided fractionation of the hexane extract obtained from the medicinal plant Myroxylon balsamum (red oil) was conducted in preparative thin layer chromatography on silica gel. The obtained fractions and some terpenoids and phenylpropanoids were assayed as larvicidal on third instar Aedes aegypti larvae, NPPN colony. The results indicate that the sesquiterpene nerolidol was the active constituent in the extract and that the sesquiterpenes were more active than the monoterpenes and phenylpropanoids utilized in this study. Lipophilicity seems to be an important property for the activity since the compounds with hydroxyl, carbonyl and methoxyl groups were less active. The results confirm also that essential oils can be a good tool for the control of dengue.

A importância da análise de especiação do chumbo em plasma para a avaliação dos riscos à saúde

Lead absorption is influenced by the species that are formed and the physicochemical characteristics of lead, among others. Lead plasma concentration is < 5% of total blood lead and represents the biologically active fraction able to cross the cell membranes. Health risks mainly depend on a specific metal and its species. Speciation analysis is the analytical activity of identifying and determining different metal species. Chromatographic methods are very useful in the identification of species and the techniques most used to determine metals in biological fluids are ICP OES/MS and AAS. Lead speciation analysis in blood plasma is fundamental for understanding and evaluating the interaction mechanisms between that analyte and its biological targets.

A poluição gerada por máquinas de combustão interna movidas à diesel - a questão dos particulados. Estratégias atuais para a redução e controle das emissões e tendências futuras

The exhaust emissions of vehicles greatly contribute to environmental pollution. Diesel engines are extremely fuel-efficient. However, the exhaust compounds emitted by diesel engines are both a health hazard and a nuisance to the public. This paper gives an overview of the emission control of particulates from diesel exhaust compounds. The worldwide emission standards are summarized. Possible devices for reducing diesel pollutants are discussed. It is clear that after-treatment devices are necessary. Catalytic converters that collect particulates from diesel exhaust and promote the catalytic burn-off are examined. Finally, recent trends in diesel particulate emission control by novel catalysts are presented.

Estresse oxidativo, lesões no genoma e processos de sinalização no controle do ciclo celular

The generation of reactive oxygen species (ROS) may be both beneficial to cells, performing functions in intracellular signaling and detrimental, modifying cellular biomolecules. ROS can cause DNA damage, such as base damage and strand breaks. Organisms respond to chromosome insults by activation of a complex and hierarchical DNA-damage response pathway. The extent of DNA damages determines cell fate: cell cycle arrest and DNA repair or cell death. The ATM is a central protein in the response to DNA double-strand breaks by acting as a transducer protein. Collected evidences suggest that ATM is also involved in the response to oxidative DNA damage.

Controle da biossíntese de poli-hidroxialcanoatos bacterianos através do fluxo de substratos

Manipulation of the flux of substrates was utilized to control the amount of 3-hydroxyvalerate and 3-hydroxy-4-pentenoate produced by Burkohlderia sp. The 3HV production rate was directly proportional to the propionic acid uptake rate with the last one completely directed to 3HV biosynthesis. The 3HPE production rate was inversely proportional to the sucrose uptake rate probably due to operation of the glyoxylate cycle.

Uso da pressão gerada por uma coluna de água para controle da vazão em sistemas de análises em fluxo

This work presents a new approach to control the flow rate in hydrodynamic flow experiments. The combination of air pressure generated by an aquarium air pump and the pressure generated by a water column were used for this purpose. This device supports a stable flow rate without pulsation for a long period of time. Furthermore, the flow rate can be easily controlled at various values in one or more streams. The performance of this approach was investigated using Fe(CN)6(4-) solutions in flowing systems using amperometric and voltammetric detection in wall-jet configuration. The results showed that the performance of the proposed device was better than a commercial peristaltic pump. It suggests that this approach can be used successfully in flow analysis systems.

O papel dos sulfetos volatilizados por acidificação no controle do potencial de biodisponibilidade de metais em sedimentos contaminados de um estuário tropical, no sudeste do Brasil

Measurements of acid volatile sulfide (AVS) and simultaneously extracted metals (SEM) were combined in order to verify the ecological hazard of contaminated sediments from the Santos-Cubatão Estuarine System (SE Brazil), which is located in one of the most industrialized areas in the Latin America. Intertidal sediments from the Morrão River estuary were collected seasonally in short cores. The redox conditions, organic matter contents and grain-size were the main controlling factors on SEM distribution. However, clear relationships among these variables and AVS were not observed. The molar SEM/AVS ratios were frequently > 1 especially in the summer, suggesting major metal bioavailability hazard in this humid hot season.

Exposição humana a substâncias químicas potencialmente tóxicas na dieta e os riscos para saúde

Humans are exposed to a variety of chemicals from the consumption of food, including undesirable compounds such as pesticides and mycotoxins. Chemical human risk assessment is a process intended to estimate the risk to a given population from the exposure to a chemical (or to a chemical group having the same mechanism of action). The process consists of four steps, namely hazard identification, hazard characterization, exposure assessment and risk characterization. Chemical dietary risk assessment is an essential procedure to establish safe food standards. In this review the tools and data sources currently used in the risk assessment process will be discussed.

Uso de CLAE no controle de qualidade em produtos comerciais de Nim: reprodutibilidade da ação inseticida

The Neem tree, Azadirachta indica, provides many useful compounds that are used as pesticides. However, the efficiency in field of products like neem oil can be committed because they have not been observed reproductive content of secondary metabolic like azadirachtin. Based on reverse-phase high-performance liquid chromatography (HPLC) a new method was developed to permit the rapid quantitative analysis of azadirachtin from seeds, extracts and oil of Neem. In the present study it was evaluated the azadirachtin quantitative variation among various Neem's extracts and seeds showing the importance of quality control for reproduction of the insecticide efficiency, using S. frugiperda as target insect.

Formação de carbamato de etila em aguardentes recém-destiladas: proposta para seu controle

The commercial sugar cane spits redistillation decreased up to 92,5% their ethyl carbamate (EC) original content. Quantitative analysis of EC in 15 samples of sugar cane spirit (alembic and column), fresh distilled and collected in situ demonstrated that the urethane is formed mostly after distillation. The average time to achieve the complete EC formation is independent of the diffuse light presence and of the distillation apparatus used. The k obs for urethane formation at 25 ºC was calculate as (3,3 ± 0,5) x 10-5/s and the activation parameters are: ΔH‡ 34 kcal/mol; ΔS‡ - 69 cal/mol K; and ΔG‡ 54 kcal/mol.

Controle da qualidade na determinação potenciométrica de sulfetos volatilizáveis por acidificação (SVA) utilizando adições de padrão

This paper presents a quality assurance and quality control protocol in order to ensure the reliability of analytical results for the determination of acid volatile sulfides in environmental samples by potentiometry. The monitoring of the ion selective sensor readings must be realized continually and particularly in this situation where the analyte is susceptible to transformation and volatilization. Potentiometry with the standard addition was presented as a rapid, accurate, precise, feasible as well as a low cost technique. Concentrations of the analyte in the range of 0.49 to 1.02 mg L-1 were tested with percentage recoveries varying from 89 to 113%.

Síntese e controle de qualidade da ureia enriquecida em 13C para diagnóstico da Helicobacterpylori (HP)

The aim of the study was to synthesize the urea (13CO(NH2)2), with 99% 13C atoms, and to perform a quality analysis for the diagnosis (breath test) of Helicobacter pylori. Furthermore, the process was submitted to economic analysis. The reaction was performed in a stainless steel reactor, lined with polytetrafluoroethylene, under low pressure and temperature. The synthesis method was shown to be appropriate (2.35 g; 81.9% yield), evidenced by physico-chemical and microbiological results, according to Brazilian legislation. The production and diagnosis costs were competitive compared with national and international market values, rendering this a valuable tool in clinical medicine.

Implementação de um método robusto para o controle fiscal de umidade em queijo minas artesanal. Abordagem metrológica multivariada

This study developed and validated a method for moisture determination in artisanal Minas cheese, using near-infrared spectroscopy and partial-least-squares. The model robustness was assured by broad sample diversity, real conditions of routine analysis, variable selection, outlier detection and analytical validation. The model was built from 28.5-55.5% w/w, with a root-mean-square-error-of-prediction of 1.6%. After its adoption, the method stability was confirmed over a period of two years through the development of a control chart. Besides this specific method, the present study sought to provide an example multivariate metrological methodology with potential for application in several areas, including new aspects, such as more stringent evaluation of the linearity of multivariate methods.

TRIHALOMETANOS EM ÁGUA POTÁVEL E RISCOS DE CÂNCER: SIMULAÇÃO USANDO POTENCIAL DE INTERAÇÃO E TRANSFORMAÇÕES DE BÄCKLUND

We briefly investigated the well-known correlation of trihalomethanes, present in fresh water, with cancer hazard in humans. A transient alternative method of chemical simulation using Bäcklund Transformations and Quantum Mechanics is presented. Finally, the method was applied to simulate the interaction between Trichloridemethane and Alanine - as well as its amino and carboxyl groups.