Methodology to evaluate stress corrosion cracking in ethanol environments, applied to circumferential welds on API 5 L steel pipelines.

This work presents an experimental methodology developed to perform fatigue crack growth (FCG) and slow strain rate (SSR) tests in ethanol environments aiming to evaluate stress corrosion cracking (SCC) susceptibility of circumferential welds on steel pipelines. FCG and SSR specimens were machined from a welded pipe and the notches were properly designed to promote crack propagation in the different regions of the weld. Tests were carried out keeping the crack-tip region fully immersed in an ethanol solution, which was fueled by a circulation system to ensure replenishment and aeration throughout the test.

DESI-MS imaging and NMR spectroscopy to investigate the influence of biodiesel in the structure of commercial rubbers.

Biodiesel has been introduced as an energetic matrix in several countries around the world. However, the affinity of biodiesel with the components of petrodiesel engines is a growing concern. In order to obtain information regarding the effect of biodiesel on the rubber structure, nuclear magnetic resonance technics under a new technology named as comprehensive multiphase (CMP NMR) and the imaging through desorption electrospray ionization mass spectrometry (DESI-MS imaging) were used.

Endophytic fungi as a source of biofuel precursors.

Endophytic fungi, isolated from a number of different species of tropical plants, were investigated for lipid biodiesel precursor production. The extracts produced from liquid cultures of these fungi were subjected to acidcatalyzed transesterification reactions with methanol producing methyl esters and then analyzed through chromatographic (GC-FID) and spectrometric techniques (MS, NMR ¹H). The European Standard Method, EN 14103, was used for the quantification of methyl esters extracted from the fungi of the species and genera studied.

Evaluation of biodiesel-diesel blends quality using 1H NMR and chemometrics.

In this work, the use of (1)H NMR spectroscopy and statistical approach to the evaluation of biodiesel-diesel blends quality is described. Forty-six mixtures of oil-diesel, biodiesel-diesel, and oil-biodiesel-diesel were analyzed by (1)H NMR and such data were employed to design four predictive models. Thirty-six mixtures were used in the calibration set and the others in the validation.

Trypanocidal activity of quinonemethide triterpenoids from Cheiloclinium cognatum (Hippocrateaceae).

We report the trypanocidal activity of quinonemethide triterpenoids isolated from root extracts of Cheiloclinium cognatum, a plant of the Hippocrateaceae family, collected in the Cerrado Reserve at Universidade Federal de Goiás, Brazil. The trypanocidal activity assays showed an effect on the blood trypomastigote forms of the Y strain of Trypanosoma cruzi where tingenone and tingenol demonstrated activity on the parasite. Their structures were elucidated on the basis of spectral data, particularly COSY, HMQC and HMBC experiments, and chemical transformations.