n-alkanes from Paepalanthus Mart. species (Eriocaulaceae)

Este trabalho apresenta o estudo de substâncias apolares obtidas a partir de plantas pertencentes ao gênero Paepalanthus Mart. (Eriocaulaceae). Hidrocarbonetos alifáticos de cadeias longas lineares foram identificados por CG-DIC e CG-EM. Os resultados indicam que as espécies de Paepalanthus subg. Platycaulon apresentam perfil homogêneo, com cadeias carbônicas de n-alcanos variando de C25 a C31, com a maioria das amostras apresentando freqüências maiores dos homólogos C27 e C29. As espécies do subgênero Paepalocephalus podem ser diferenciadas pela distribuição dos n-alcanos principais. P. macrocephalus, uma espécie da subseção Aphorocaulon, apresenta perfil com alcanos de cadeia ímpar, enquanto P. denudatus e P. polyanthus, espécies da seção Actinocephalus, apresentam perfil bem distinto, com grande número de cadeias mais curtas e alta freqüência de cadeias com número par de carbonos, especialmente P. polyanthus. Os resultados obtidos indicam que a distribuição de nalcanos pode ser útil como caráter taxonômico, assim como as substâncias mais polares, como os flavonóides glicosilados.

Multi-method Study on Aquatic Humic Substances from the Rio Negro - Amazonas State/Brazil: Emphasis on Molecular-Size Classification of their Metal Contents

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Thermal behavior of copper(II) pseudohalide complexes containing bidentate amines

Pseudohalide complexes of copper(II) with aliphatic bidentate amines, [Cu(N-3)(2)(N,N-diEten)](2) 1, [Cu(NCO)(2)(N,N-diEten)](2) 2, [Cu(NCO)(2)(N,N-diMeen)](2) 3, [Cu(N-3)(NCS)(N,N'-diMeen)](2) 4 and [Cu(N-3)(NCO)(N,N-diMeen)](2) 5 (N,N-diEten=N,N-diethylethylenediamine; N,N-diMeen=N,N- dimethyl-ethylenediamine and N,N'-diMeen = N,N'-dimethylethylenediamine), were prepared, characterized and their thermal behavior was investigated by TG curves. According to thermal analysis and X-ray diffraction patterns all compounds decomposed giving copper(II) oxide as final product. The mechanisms of decomposition were proposed and an order of thermal stability was established.

Qualitative determination of indole alkaloids, triterpenoids and steroid of Tabernaemontana hilariana

This paper reports the separation and identification of indole alkaloids, steroids and triterpenoids from the ethanolic extracts of Tabernaemontana hilariana (Apocynaceae). The alkaloidal fractions from the ethanolic extracts obtained (root barks, green fruits, ripe fruits and seeds) were fractionated and analysed by thin-layer chromatography, capillary gas chromatography-flame ionization detection (cGC-FID) as well as by high-resolution gas chromatography-mass spectrometry (HRGC-MS). 3-Hydroxycoronaridine, ibogamine, coronaridine pseudoindoxyl, coronaridine, catharanthine, voacangine hydroxyindolenine, voacangine pseudoindoxyl, tabernanthine, tetraphyllicine, 3-hydroxyvoacangine, voacangine, isovoacangine and 3-oxocoronaridine were identified. The insoluble fraction of ethanolic extracts obtained from the root barks and green fruits were analysed and ten aliphatic constituents were also identified by cGC-FID and HRGC-MS. (C) 1998 Elsevier B.V. B.V. All rights reserved.

Assessment of maturity degree of composts from domestic solid wastes by fluorescence and fourier transform infrared spectroscopies

Methods of assessment of compost maturity are needed so the application of composted materials to lands will provide optimal benefits. The aim of the present paper is to assess the maturity reached by composts from domestic solid wastes (DSW) prepared under periodic and permanent aeration systems and sampled at different composting time, by means of excitation-emission matrix (EEM) fluorescence spectroscopy and Fourier transform infrared spectroscopy (FT-IR). EEM spectra indicated the presence of two different fluorophores centered, respectively, at Ex/Em wavelength pairs of 330/425 and 280/330 nm. The fluorescence intensities of these peaks were also analyzed, showing trends related to the maturity of composts. The contour density of EEM maps appeared to be strongly reduced with composting days. After 30 and 45 days of composting, FT-IR spectra exhibited a decrease of intensity of peaks assigned to polysaccharides and in the aliphatic region. EEM and FT-IR techniques seem to produce spectra that correlate with the degree of maturity of the compost. Further refinement of these techniques should provide a relatively rapid method of assessing the suitability of the compost to land application.

Identification of polycyclic aromatic hydrocarbons in sugar cane soot by gas chromatography mass spectrometry

Fly soot samples collected in the sugar cane fields after the process of burning were extracted in a Soxhlet apparatus (methylene chloride:methanol 4:1). The extracts were fractionated on silica gel Sep-Pak cartridges into three fractions. A gas chromatographic-mass spectrometric study of the fly soot extracts allowed the identification of the PAH with mutagenic and carcinogenic properties. Large amounts of aliphatic hydrocarbons, fatty acid esters and some PAHs were identified by GCMS in full scan mode. GC-MS in the selective ion monitoring mode (SIM) was suitable for the determination of many PAHs, which are often present in the burnt biomass. 31 PAHs and 7 thiophens derivatives were identified. The presence of these compounds should be regarded as a caution to workers and the general population to avoid exposure to the fly soot.

BEHAVIOR OF THE ANION-RADICALS ELECTROCHEMICALLY GENERATED IN THE REDUCTION OF NOSYL AMIDES

The behaviour of nitrobenzenesulfonamide anion radicals generated from the electrochemical reduction of aliphatic and aromatic amines protected by nitrobenzenesulfonyl (nosyl) groups in N,N-' dimethylformamide has been reported. The species have been characterized by voltammetry and optical and electron spin resonance spectroscopies. The visible spectra of the anion radicals were recorded and the hyperfine splitting constants were assigned to specific proton positions and nitrogen nuclei of the molecule. The stabilities of the anion radicals are affected by electronic properties of the protecting group and specific features of the amines, which show direct influence on the route of cathodic cleavage of the nitrobenzenesulfonamides.

Butanolides as a common feature of Iryanthera lancifolia and Virola surinamensis

A comparative phytochemical study between pericarps of Iryanthera lancifolia and Virola surinamensis showed that the first one contains a new pair of epimeric 2-alkenyl-gamma-lactones, besides an aryltetralinic lignan and one tocotrienol, while the second species contains the lignans, galgravin and veraguensin, seven juruenolides: juruenolides C, D, F, G and epi-juruenolides D, F, G, together with three pairs of epimeric aliphatic 2-alkenyl-gamma-lactones. Juruenolide F, epi-juruenolides D, F, G and the 2-alkenyl-gamma-lactones are new natural compounds. (C) 1998 Elsevier B.V. Ltd. All rights reserved.

EVOLUTION PATTERNS OF THE SOIL ORGANIC-MATTER IN SOME AGRICULTURAL SYSTEMS IN THE BRAZILIAN CERRADO REGION

Several changes in the soil humus characteristics were observed after clearing the Central Brazil virgin forest. When compared with the original ''Cerrado'' forest, the soils from the agricultural systems showed increased values for cation exchange capacity, total organic matter and non-extractable humin. The humic acid fraction underwent some changes suggesting increased oxidation and decreased aliphatic content. The soil organic N tends to accumulate in the insoluble humus fractions.The above changes were much less intense when the virgin forest was transformed into pastures. Under these conditions, the most significant changes were the reduction of readily biodegradable soil organic matter fractions.In view of the intensity of the lixiviation processes in the area studied, the above changes may be connected with the reduction in aggregate stability observed in the cleared sites.In general, the characteristics of the humus formations in the ''Cerrado'' region suggested high resistance to external factors, which is in part attributed to the active insolubilization of humic colloids by the Al and Fe oxides. In the absence of erosive processes in the cleared sites, additional humus stability may conform both to selective biodegradation and/or lixiviation of the humic colloids, or to the effects of the fire used in soil management.

Dipole moments in Langmuir monolayers from aromatic carboxylic acids

The three-layer capacitor model proposed by Demchak and Fort [J. Colloid Interface Sci. 46 (1974) 191] is employed to relate measured surface potentials of Langmuir monolayers from a series of polyphenyl carboxylic acids to molecular dipole moments calculated using semiempirical quantum methods. The effective dielectric constant at the air/monolayer interface is 3.0 +/- 0.6, very close to that estimated for aliphatic compounds. Good agreement between theory and experiment is obtained by adopting a dielectric constant of 6.4 for the monolayer/water interface and a contribution from the water reorientation of -0.064 +/- 0.006 D, which shows that the parameters in the DF model are essentially the same as for aliphatic amphiphiles, such as esters, acids, alcohols and ethers. (C) 2000 Elsevier B.V. B.V. All rights reserved.

Influence of different types of non-resorbable suture material on the healing of extraction wounds--a histological study in rats.

The influence of different non-resorbable suture materials on the healing of tooth extraction wounds was examined in 120 adult male albino rats. Nylon gave the best biological results for healing of the mucosa and dental socket. Silk and cotton produced considerable delay of socket healing. Healing was only mildly delayed by polyester suture, with a short moderate inflammatory reaction at the initial stage.

Reaction of the human gingival tissue to different suture materials used in periodontal surgery.

The gingival reaction to 4 different suture materials used in periodontal surgery was studied in 36 patients. The gingiva was sutured prior to surgery and biopsies were taken at 3, 7 and 14 days to observe the tissue reaction. The histological examination showed that silk caused the most intense and longest inflammatory response. Polyester and perlon provoked shorter, less intense tissue reactions than silk, and nylon caused the least inflammatory response, with earlier tissue repair.

Natural fiber reinforced unsaturated polyester composites - An approach on compression molding

This work has been performed at Tapetes Sao Carlos-Brazil with the cooperation of the DaimlerChrysler Research Center Team in Ulm - Germany. The objective of the present paper is to report the results obtained with natural fiber reinforced unsaturated polyester (UP) composites, concerning surface quality measurements. The fibers that have been chosen for this work were sisal and curaua. The samples were produced by compression molding technique and afterwards submitted to three different tests, namely: a) thermal aging; b) water absorption and c) artificial weathering. The surface parameters measured before and after the tests were gloss, haze, short and long-waviness. The results have shown that after the tests there is a high loss of gloss, a high increase in haze, and a high increase in short and long-waviness as well. Curaua reinforced composites had a slightly better behavior when compared with sisal reinforced composites. The effect of the presence of filler and the addition of thermoplastic polyester (TP) on the material behavior has not been evidently detected. This result shows that the conventional technology/methods applied to UP-Fiberglass systems cannot be transferred to natural fibers without any modification. The fiber-matrix interaction and its response to the presence of additives must be fully understood before a successful processing route can be developed for painted natural fibers reinforced UP. Copyright © 2001 Society of Automotive Engineers, Inc.

Clinical evaluation of proximal contacts of Class II esthetic direct restorations

Objective: This study evaluated the effectiveness of proximal contacts in Class II restorations using two types of matrix bands (steel and polyester) with two different restoration techniques (incremental and with prepolymerized particles). Method and materials: Eighty-eight Class II adjacent restorations using Prodigy resin composite were performed: 44 with the incremental technique (22 with steel matrix bands, 22 with polyester matrix bands) and 44 utilizing prepolymerized resin particles (22 steel matrix, 22 polyester matrix). The restorations were clinically evaluated at baseline and at 6, 12, and 18 months. Proximal contacts obtained immediately after restoration procedure in all restorations were satisfactory. Results: No statistically significant alterations were found in 18 months of evaluation. Conclusion: Regardless of the utilized resin composite, there were no differences in the amount of proximal contact variations with respect to tested techniques and matrices.

Thermoanalytical study of praziquantel-loaded PLGA nanoparticles

Polymeric nanoparticles have received great attention as potential controlled drug delivery systems. Biodegradable polymers has been extensively used in the development of these drug carriers, and the polyesters such as polylactic acid, polyglycolic acid and their copolymers as poly-lactide-co- glycolide are the most used, considering its biocompatibility and biodegradability. Thermal analysis techniques have been used for pharmaceutical substances for more than 30 years and are routine methods for screening drug-excipient interactions. The aim of this work is to use thermal analysis to characterize PLGA nanoparticles containing a hydrophobic drug, praziquantel. The results show that the drug is in an amorphous state or in disordered crystalline phase of molecular dispersion in the PLGA polymeric matrix and that the microencapsulation process did not interfere with the chemical structure of the polymer, mantaining the structural drug integrity.