Caracterização dos produtos líquidos e do carvão da pirólise de serragem de eucalipto

This study proposes the low temperature pyrolysis as an alternative conversion process for residual biomass and for obtaining gaseous, liquid and solid chemical feedstocks. Using a bench electrical pyrolysis oven, four product fractions from eucalyptus sawdust were obtained: a gaseous one, two liquid (aqueous and oily), and a solid residue (char). These products were characterized by different analytical methods. The liquid fractions showed themselves as potential sources for input chemicals. The residual char revealed appreciable adsorption capability. The process demonstrated good efficiency, generating at least two fractions of great industrial interest: bio oil and char.

Teores de carbamato de etila e outros componentes secundários em diferentes cachaças produzidas em três regiões do estado de Minas Gerais: Zona da mata, sul de minas e vale do jequitinhonha

Minas Gerais is the highest producer of handmade spirits. Research has been carried out aiming to contribute to progress. Thus, the goal of this work is to evaluate the quality of spirits in three different regions of Minas Gerais state. We analyzed ethyl carbamate, alcoholic grade, volatile acidity, higher alcohols, aldehyde, esters, methanol, furfural and copper. The values obtained for ethyl carbamate varied from undetectable to 643.5 µg L-1, with only one region not following the legislation (150 µg L-1). Most of the compounds in the spirits were present within the limits estabilished by the legislation.

Isolamento e atividades biológicas de produtos naturais das esponjas monanchora arbuscula, aplysina sp. petromica ciocalyptoides e topsentia ophiraphidites, da ascídia didemnum ligulum e do octocoral carijoa riisei

The investigation of extracts from six species of marine invertebrates yielded one new and several known natural products. Isoptilocaulin from the sponge Monanchora aff. arbuscula displayed antimicrobial activity at 1.3 mg/mL against an oxacillin-resistant strain of Staphylococcus aureus. Five inactive known dibromotyrosine derivatives, 2 6, were isolated from a new species of marine sponge, Aplysina sp. The sponges Petromica ciocalyptoides and Topsentia ophiraphidites yielded the known halistanol sulfate A (7) as an inhibitor of the antileishmanial target adenosine phosphoribosyl transferase. The ascidian Didemnum ligulum yielded asterubin (10) and the new N,N-dimethyl-O-methylethanolamine (11). The octocoral Carijoa riisei yielded the known 18-acetoxypregna-1,4,20-trien-3-one (12), which displayed cytotoxic activity against the cancer cell lines SF295, MDA-MB435, HCT8 and HL60.

Biologia química: uma estratégia moderna para a pesquisa em produtos naturais

This paper presents an overview of the Natural Products Research in Brazil in the last five years (2002-2006), and also discusses how some relevant aspects of the Chemical Biology area could create new research opportunities and challenges for the natural product chemists. In addition, some aspects of the scientific policies and their impact on current projects are discussed.

Estudo da mobilização de metais e elementos traços em ambientes aquáticos do semi-árido brasileiro aplicando análises de componentes principais

The spatial and temporal retention of metals has been studied in water and sediments of the Gavião River, Anagé and Tremedal Reservoirs, located in the semi-arid region, Bahia - Brazil, in order to identify trends in the fluxes of metals from the sediments to the water column. The determination of metals was made by ICP OES and ET AAS. The application of statistical methods showed that this aquatic system presents suitable conditions to move Cd2+ and Pb2+ from the water column to the sediment.

Determinação voltamétrica de ciclamato de sódio em produtos dietéticos empregando um eletrodo de diamante dopado com boro

The use of square-wave voltammetry in conjunction with a cathodically pre-treated diamond electrode for the analytical determination of sodium cyclamate is described. The samples were analyzed as received in a 0.5 mol L-1 H2SO4 solution in the concentration range from 5.0 × 10-5 mol L-1 to 4.1 × 10-4 mol L-1, with a detection limit of 4.8 × 10-6 mol L-1. The RSD was smaller than 1.2 % and the proposed method was applied with success in the determination of sodium cyclamate in several dietary products.

Classificação de refrigerantes através de análise de imagens e análise de componentes principais (PCA)

This paper describes an approach for the colour-based classification of RGB (red-green-blue) images, acquired using a common scanner, of commercial carbonated soft drinks. Mean histograms of image colour channels were evaluated for the PCA classification of 29 brands of Guaraná, Cola, and orange flavors. Loadings for principal component axes resulted in different patterns for sample grouping on score plots according to RGB histograms. pH, sorbic acid and sucrose measurements were also correlated to the analyzed brands through PCA score plots of the digitalized images.

Avaliação da qualidade do corpo hídrico do rio Tibagi na região de Ponta Grossa utilizando análise de componentes principais (PCA)

The aim of this paper was to evaluate alterations in the quality of the water of the Tibagi River caused by the urban and industrial activities in the region of Ponta Grossa. The study involved the monitoring of physico-chemical and microbiological parameters of the water body, which were evaluated by a principal components analysis routine. Sample collections were carried out monthly during one year (October of 2005 to September of 2006), at 3 sampling points: upstream and downstream of the industrial district and downstream from the city of Ponta Grossa. The principal components analysis showed the effect of point sources associated with industrial activity, which contribute to the rise of total concentration of amoniacal nitrogen and the reduction of dissolved oxygen in the studied region.

Desenvolvimento de um procedimento biamperométrico para determinação de sacarina em produtos dietéticos

In this work was developed a method for the determination of saccharin in dietary products by a biamperometric titration, using two silver electrodes as working electrodes and silver nitrate as titrant. It were used products as juices (light) and sweeteners with saccharin in concentrations ranged from 8.73 x 10-5 mol L-1 to 1.0 x 10-2 mol L-1, and the results were in close agreement with those data found using a HPLC method at a confidence level of 95%. The main advantages of the proposed method are its simplicity, rapid and low cost.

Gliceroquímica: novos produtos e processos a partir da glicerina de produção de biodiesel

Glycerol is a byproduct of biodiesel production through transesterification of oils and fat. This article discusses the chemical transformation of glycerol in ethers, acetals and esters of high technological applications, especially in the fuel sector. Glycerol hydrogenolysis, dehydration to acrolein and oxidation are discussed as well, to show the potential use of glycerol for production of plastic monomers. Finally, the article shows other transformations, such as syn gas production, epichloridrin and glycerin carbonate.

Fotoprotetores derivados de produtos naturais: perspectivas de mercado e interações entre o setor produtivo e centros de pesquisa

Ultraviolet radiation is the major exogenous mediators of skin damage. To prevent such damage, sunscreen products are used. New research aims at both the elucidation of new sunscreen compounds, as well as new assets for supporting and synergistic action. In this article it is presented a systematic data of innovation for sunscreen and a discussion on prospects for partnership between universities and enterprises, where it is believed that the innovations in cosmetics, driven by the constant demand of the market in new products, may be a stimulus for the interactions between university and company in Brazil.

Modificação química de argilas: desafios científicos e tecnológicos para obtenção de novos produtos com maior valor agregado

Chemical modification of clays is possible due to their ion-exchange and adsorption capacities, which allows the adjustment of the physicochemical properties of the surfaces of their layers. This modification makes possible the use of clays to produce a great number of new materials, which range from coarse applications such as oil based drilling fluids to refined applications such as pharmaceutical products. This article intends to expose where there is still space for research and investment aiming at the performance improvement of clay-based materials.

Sistema multicomutado de análise em fluxo para determinação de amônio e monocloramina em águas residuais e produtos de desinfecção

A binary sampling flow analysis system equipped with gas diffusion cell was developed for NH4+ and/or NH2Cl determination in wastewater and disinfection products samples based on the Berthelot reaction of the NH2Cl diffused through the semi-permeable PTFE membrane. The effect of the analytical conditions related to the reaction and flow parameters were evaluated and N-NH4+ and N-NH2Cl were determined in concentration ranges from 0.17 to 5 mg L-1 and from 0.5 to 14.5 mg L-1, respectively. Limits of detection (3σ) of 50 and 140 µg L-1 for N-NH4+ and N-NH2Cl were calculated, respectively, and RSD of 5 and 2% were calculated for 10 consecutive determinations of N-NH4+ (1 and 3 mg L-1) and N-NH2Cl (3 and 9 mg L-1), respectively with 30 determinations h-1.

Contaminação de produtos de higiene e cosméticos por n-nitrosaminas

N-nitrosamines are carcinogenic compounds that have been found during the last three decades in a variety of consumer products, including cosmetic and personal care products, and their raw materials. These compounds are formed from amine precursors and nitrosating agents present in the formulations. This paper reviews the formation and occurrence of N-nitrosamines in cosmetic products, as well as presents considerations about analytical, toxicological and regulatory aspects.

Composição química dos componentes voláteis de Capsicodendron dinisii Schwancke (Canellaceae)

The volatile components of the stem bark of Capsicodendron dinisii were obtained by hydrodistillation using a modified Clevenger-type apparatus. The chemical compounds were identified using the arithmetic index and confirmed by GC-MS. Twenty-three compounds suggest the identified representing almost 90% of the total oil composition. Limonene (68.5%) was the major compound found. The stereochemistry of limonene was determined and was found to be represented by (+)-limonene (94%) and (-)-limonene (6%). The presence of drimenol (0.7%), a drimane sesquiterpenoid, confirmed the volatile components characteristics of the Canellaceae family.