François diederich

"My favorite food is Japanese cuisine. The most important thing I learned from my parents is a love for dedicated and reliable craftsmanship …?" This and more about Fran?ois Diederich can be found on page 3302.     

François-Marie Raoult: Past and Modern Look

The academic and research career of Raoult is an example of success against the odds. He was born into a family of modest means and made his academic career far from Paris, the center of scientific power and means. He did his research on the behavior of solutions in general, and electrolytes in particular, before the concepts of molecular association, salt dissociation, and molecular structure had been established. In spite of this, by precise experimental work and brilliant intuition he made fundamental and everlasting contributions to thermodynamics. Raoults results are discussed against the scientific background of his time and then reanalyzed using current thermodynamic ideas.     

Comprehensive two-dimensional gas chromatography for fingerprint pattern recognition in cachaça production

Cacha?a samples were studied by means of comprehensive two-dimensional gas chromatography and time-of-flight mass spectrometry (GCxGC/TOFMS) during the fermentation process and after ageing in different wood materials. The analyses of the aroma compounds were performed after headspace-solid phase microextraction method (HS-SPME) using an 85microm polyacrylate (PA) fibre. Fingerprint monitoring of the distillation process allowed the easy determination of the turning points of the process and high-resolution comparison of cabe?a (head), cora??o (core) and cauda (tail) fractions. The ageing process in different wood materials was well characterised through fingerprint similarity observations; in the absence of a suitable metric for expressing the overall similarity, here we use a visual and retention time comparison to identify co-incident peaks and those that differ between samples. For quality control purposes, a simple observation of the contour plots obtained can thus allow the identification of the type of wood used in the ageing process, and the process of ageing, without further statistical treatment or peak identifications. In this manner, peaks, which discriminated most between the different mixtures studied were readily found, i.e. unique compounds were identified in each stage of the distillation process. Approximate first dimension linear retention indices (LRI) for these identified compounds were calculated in a bi-dimensional polar/non-polar column set in the GCxGC experiment and were used in conjunction with mass spectral library searching for tentative identification. Along the progression of the distillation process, 70 compounds appear to visually discriminate between samples and their retention indices are indicated, presenting good correlation with literature data.     

Amorçage de la décohésion dans l'essai d'arrachement

By revisiting the classical formulation of fracture mechanics, the study of debonding in composite materials can be modelised by a principle of least energy. We are interested in the study of the fibre pull-out problem. Considering a cylindric reinforced beam characterised by the ε ratio of its radius to its length, an energy study shows, by taking into account free-edge effects near the interface, that debonding happens suddenly when the length is of order √ε.     

Quantitative determination of jatrophone in "cachaça" prepared with Jatropha elliptica

A method for sample preparation and analysis by high performance liquid chromatography with UV detection (HPLC-UV) was developed for analysis of jatrophone in "cacha?a" prepared with Jatropha elliptica, administered orally, employed in Brazil for the treatment of venomous snake bites. The linearity, accuracy, precision of the procedure was evaluated. Analytical curve for jatrophone was linear in the range of 16.24-81.20 microg ml(-1). The recovery of the jatrophone in the samples analyzed was 98.99-99.89%. The percent coefficient of variation for the quantitative analysis of the "cacha?a" in the analyses was under 2%.     

Differentiation of rum and Brazilian artisan cachaça via electrospray ionization mass spectrometry fingerprinting

Rum and cacha?a are sugarcane distillates produced on large scales and of similar composition, and their differentiation is currently a subject of commercial dispute and a challenging analytical task. We have investigated the ability of direct-infusion electrospray ionization mass spectrometry in the negative ion mode, i.e. ESI(-)-MS, to distinguish between samples of these distillates. ESI(-)-MS fingerprints were collected for some samples of Brazilian artisan cacha?a, aged in two types of wooden casks, i. e. amburana (Amburana cearensis) and jequitibá (Cariniana estrellensis), and of commercial rum. The mass spectra were found to be very distinctive, showing sets of diagnostic ions for each type of sample, i. e. (1) cacha?a aged in amburana (m/z 271, 313, 377) and jequitibá (m/z 171, 255, 455) casks; and (2) commercial rum (m/z 89, 97, 179, 255, 283). When applied to the ESI(-)-MS data, principal component analysis and hierarchical cluster analysis split rum and cacha?a samples into well-defined groups. Moreover, the two types of cacha?a samples aged in wooden casks of amburana or jequitibá were also split into two distinct groups. Direct-infusion ESI(-)-MS can therefore be potentially applied to the rapid, simple, and accurate differentiation of these commercially important sugarcane distillates.     

Marbles in the façade of the "Certosa di Pavia": a physico-chemical study

In the framework of an interdisciplinary research project on the well known monastery "Certosa di Pavia", the thermal and structural properties of marbles employed in the construction of the fa?ade of the basilica were investigated in order to detect the main decomposition phenomena occurring on the monument surface. The results obtained by means of thermogravimetric and differential thermal analyses, as well as by means of X-ray diffraction and IR spectroscopy, allowed one to characterize samples taken from various sculptures of the fa?ade and to bring out the degradation phenomena occurring in some of them, in particular the formation of "black crusts" with a high content in gypsum. The present findings are in fair agreement with those reported by other research groups which also studied with different techniques the construction materials of this monument.     

Development of a certified reference material for cachaça: an effective material for quality assurance

Cachaça is the typical and genuine denomination for the sugar cane beverage produced in Brazil. It has an alcoholic content between 38 and 48 % by volume, at 20 °C, and is obtained from the distillation of fermented sugar cane juice with the possible addition of up to 6 g/L of sugar, expressed by sucrose. This paper aims to outline the approach taken for the certification of the mass fraction of individual alcohols and their associated uncertainties in a cachaça certified reference material (CRM) produced by the Organic Analysis Laboratory of the Chemical Metrology Division of Inmetro. The requirements of ISO Guide 31, ISO Guide 34 and ISO Guide 35 were followed for the certification. This included the assessment of the degree of homogeneity of the material, the short-term stability study to determine the transport conditions, the long-term stability study to establish the shelf life and storage conditions of the CRM and the characterization process. The certified values were determined by two analytical techniques: gas chromatography coupled to mass spectrometry and gas chromatography with flame ionization detection. In order to support the routine testing of cachaça, in helping analytical laboratories validate and standardize their methods, the certified reference material (CRM 02.1/10.003b) was developed and certified for the mass fractions of methanol (9.18 mg/100 g ± 0.82 mg/100 g), 2-butanol (4.15 mg/100 g ± 0.40 mg/100 g), 1-butanol (1.30 mg/100 g ± 0.18 mg/100 g), isobutanol (24.0 mg/100 g ± 1.0 mg/100 g) and 1-propanol (29.4 mg/100 g ± 1.3 mg/100 g) in a spiked cachaça.     

Mouvement hydrodynamique de fluide visqueux entre deux plans se déplaçant parallèlement

A model of exact solution is proposed about flows with domains bounded by two planes moving in any manner but remaining parallel. Gravity, stratification and dilatations owing to small differences of temperature are taken into account. The miscellaneous forms of streamlines occuring in the flow are characterised and classified thorougthly.     

Phenolic compounds and antimicrobial activity of olive (Olea europaea L. Cv. Cobrançosa) leaves

We report the determination of phenolic compounds in olive leaves by reversed-phase HPLC/DAD, and the evaluation of their in vitro activity against several microorganisms that may be causal agents of human intestinal and respiratory tract infections, namely gram positive (Bacillus cereus, B. subtilis and Staphylococcus aureus), gram negative bacteria (Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae) and fungi (Candida albicans and Cryptococcus neoformans). Seven phenolic compounds were identified and quantified: caffeic acid, verbascoside, oleuropein, luteolin 7-O-glucoside, rutin, apigenin 7-O-glucoside and luteolin 4'-O-glucoside. At low concentrations olive leaves extracts showed an unusual combined antibacterial and antifungal action, which suggest their great potential as nutraceuticals, particularly as a source of phenolic compounds.     

Conventional and ultrasound-assisted methods for extraction of bioactive compounds from red araçá peel (Psidium cattleianum Sabine)

The present study aimed to maximize the conventional extraction and compare it with the ultrasound-assisted method for extracting bioactive compounds obtained from the red araçá peel. The behavior of anthocyanins related to the pre-treatment of the vegetal matrix, employed solvent, extraction kinetics of both methods, the levels of total phenolic compounds, flavonoids and carotenoids, as well as the antioxidant activity were evaluated. The ultrasound-assisted extraction (40 KHz −154 W and 90 min) had an increase of 12% in the levels of anthocyanins (121.85 Eq. mg of cyanidin-3-glycoside/100 g of peel) and a 25% reduction in time extraction compared to conventional extraction by maceration (116.81 Eq. mg of cyanidin-3-glycoside/100 g of peel) using 90% ethanol, for 2 h, pH 1.5, at 40 °C and mass/volume ratio 1 g/10 mL). Analyses of the total phenolic compounds, flavonoids and carotenoids presented promising results for the ultrasound-assisted and conventional extractions, respectively. Analyzes of total phenolic compounds, flavonoids and carotenoids, show promising results for ultrasound-assisted extractions, respectively, indicating that red araçá is rich in bioactive compounds beneficial to human health, in addition to being considered natural pigments that can be used in food.     

Rôle de l'ecrouissage et des contraintes residuelles dans il'amorçage de la fissuration est corrosion sous contraintes

In this work, the influence of residual stresses and stress corrosion of cold work on cracking were studied using X ray diffraction. The results show that the crack initiation depends on the applied loading level, initial residual stresses and work hardening on the surface.