University of Bordeaux

About: University of Bordeaux is a education organization based out in Bordeaux, France. It is known for research contribution in the topics: Population & Laser. The organization has 28811 authors who have published 55536 publications receiving 1619635 citations. The organization is also known as: UB.

Identification of a powerful aromatic component of Vitis vinifera L. var. sauvignon wines: 4-mercapto-4-methylpentan-2-one

Abstract: p-Hydroxymercuribenzoic acid (pHMB), reacts reversibly with thiols. Using this principle, an extraction method of the thiols present in wines has been established. Injecting the extracts from Vitis vinifera L. var. Sauvignon wines on to a gas-chromatographic column using the purge and trap technique and a flame photometric detector enabled us to discover some sulphur compounds present in wines from this cultivar. On several capillary columns of different polarities, one of the peaks possesses the same retention time as the potent odourant, 4-mercapto-4-methylpentan-2-one, which evokes odours of box tree and cat urine. The identification of this compound in Sauvignon wines was confirmed by mass spectrometry. These results confirm previous work obtained by coupling gas chromatography and olfactometry, and show that this thiol is present in Sauvignon wines. The perception threshold of this compound in water and in wine is very low (close to 0.1 ng/1 and 3 ng/1s respectively) and despite its low concentration in Sauvignon wines, 4-mercapto-4-methylpentan-2-one seems to play a major role in the varietal aroma of the wines from this cultivar.

Laser-matter interaction in the bulk of a transparent solid: confined microexplosion and void formation

Abstract: We present here the experimental and theoretical studies of a single femtosecond laser pulse interaction inside a bulk of transparent media (sapphire, glass, polymer). This interaction leads to the drastic transformations in a solid resulting in a void formation inside a dielectric. The laser pulse energy is absorbed within a volume of approximately $0.15\phantom{\rule{0.3em}{0ex}}\mathrm{\ensuremath{\mu}}{\mathrm{m}}^{3}$ creating a pressure and temperature comparable to that in the core of a strong multi-kilo-tons explosion. The material within this volume is rapidly atomized, ionized, and converted into a tiny super-hot dense cloud of expanding plasma that generates strong shock and rarefaction waves which result in the formation of a void, whose diameter is $\ensuremath{\sim}200\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ (for a $100\phantom{\rule{0.3em}{0ex}}\mathrm{nJ}$ pulse in sapphire). The way this structure forms can be understood from high-temperature plasma hydrodynamics. We demonstrate that unique states of matter characterized by temperatures $\ensuremath{\sim}{10}^{5}\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, heating rates up to the ${10}^{18}\phantom{\rule{0.3em}{0ex}}\mathrm{K}∕\mathrm{s}$, and pressures more than 100 times the strength of any material were created using a standard table-top laser in well-controlled laboratory conditions. We discuss the properties of the laser-affected solid and possible routes of laser-affected material transformation to the final state long after the pulse end. These studies will find application for the design of new materials and three-dimensional optical memory devices, and for formation of photonic band-gap crystals.