Returns to the time axis in directed configurations

Directed configurations in dimensions 2 to 4 are investigated regarding the average number of returns to the anisotropy, or time, axis. Series expansions for this quantity, show that it vanishes asymptotically with a dimension dependent exponent equal to the critical exponent for directed animals in the corresponding dimensionality.     

On the approach to the final aperiodic regime in maps of the interval

We present a global approach to the final aperiodic regime in maps of the interval displaying a simple pattern with similarities to the Feigenbaum scheme.     

Time domain investigation on vibrational dephasing and spectral diffusion in CO-doped solid N2

Infrared picosecond accumulated photon echo experiments have been performed for the first time, using the Orsay Free Electron Laser, on the v = 0-->v = 1 transition of CO in solid nitrogen. The vibrational dephasing time is found to be exceptionally long ( T2>/=120 ns) at low temperature. The analysis of the observed spectral diffusion leads one to assume different energy transfer mechanisms depending on the CO concentration.     

A quartz crystal microbalance sensor for the determination of nitroaromatics in landfill gas

A new sensor based on oxidative combustion of nitroaromatics to NO₂ and its detection with a quartz crystal microbalance (QCM) coated with copper phthalocyanine (CuPc) was developed for determination of nitroaromatics in landfill gas. An alternative method based on gas chromatography–mass spectrometry (GC–MS) was also used in order to assess the performance of the proposed method. The results show that the analytical apparatus based on the QCM is less expensive than the GC–MS, and that the analytical error is 0.8% for both methods.     

Semisynthesis of long-chain alkyl ether derivatives of sulfated oligosaccharides via dibutylstannylene acetal intermediates

Long-chain alkyl ether derivatives of sulfated oligosaccharides were semisynthesized as follows: two naturally occurring red seaweed galactans (neutral agarose and kappa-carrageenan) were submitted to partial reductive hydrolysis to give neutral and sulfated oligosaccharide alditols. The neutral disaccharide alditol (1) and its trityl ether (5) were sulfated and/or alkylated through formation of their dibutylstannylene or (bis)dibutylstannylene acetals. In these reactions, the dibutylstannylene acetals of the terminal 1,2-diols in the alditol units were more reactive than those formed on the cis-diols of the galactopyranosidic units. This property allowed the regioselective monoalkylation of a neutral tetrasaccharide alditol (2), which contained eleven free hydroxyl groups, the highest selectivity ever observed with dibutylstannylene acetals. An alkylated/sulfated derivative (11) was also obtained through the regioselective alkylation of a naturally sulfated disaccharide alditol (10, a kappa-carrageenan derivative).     

Ethanol/water pulps from sugar cane straw and their biobleaching with xylanase from Bacillus pumilus

The influence of independent variables (temperature and time) on the cooking of sugar cane straw with ethanol/water mixtures was studied to determine operating conditions that obtain pulp with high cellulose contents and a low lignin content. An experimental 2(2) design was applied for temperatures of 185 and 215 degrees C, and time of 1 and 2.5 h with the ethanol/water mixture concentration and constant straw-to-solvent ratio. The system was scaled-up at 200 degrees C cooking temperature for 2 h with 50% ethanol-water concentration, and 1:10 (w/v) straw-to-solvent ratio to obtain a pulp with 3.14 cP viscosity, 58.09 kappa-number, and the chemical composition of the pulps were 3.2% pentosan and 31.5% lignin. Xylanase from Bacillus pumilus was then applied at a loading of 5-150 IU/g dry pulp in the sugar cane straw ethanol/water pulp at 50 degrees C for 2 and 20 h. To ethanol/water pulps, the best enzyme dosage was found to be 20 IU/g dry pulp at 20 h, and a high enzyme dosage of 150 IU/g dry pulp did not decrease the kappa-number of the pulp.     

Influence of viral infection on essential oil composition of Ocimum basilicum (Lamiaceae)

Ocimum basilicum L., popularly known as sweet basil, is a Lamiaceae species whose essential oil is mainly composed of monoterpenes, sesquiterpenes and phenylpropanoids. The contents of these compounds can be affected by abiotic and biotic factors such as infections caused by viruses. The main goal of this research was an investigation of the effects of viral infection on the essential oil profile of common basil. Seeds of O. basilicum L. cv. Genovese were sowed and kept in a greenhouse. Plants presenting two pairs of leaves above the cotyledons were inoculated with an unidentified virus isolated from a field plant showing chlorotic yellow spots and foliar deformation. Essential oils of healthy and infected plants were extracted by hydrodistillation and analyzed by GCMS. Changes in essential oil composition due to viral infection were observed. Methyleugenol and p-cresol,2,6-di-tert-butyl were the main constituents. However, methyleugenol contents were significantly decreased in infected plants.     

Radiolysis of astrophysical ice analogs by energetic ions: the effect of projectile mass and ice temperature

An experimental study of the interaction of highly charged, energetic ions (52 MeV (58)Ni(13+) and 15.7 MeV (16)O(5+)) with mixed H(2)O : C(18)O(2) astrophysical ice analogs at two different temperatures is presented. This analysis aims to simulate the chemical and the physicochemical interactions induced by cosmic rays inside dense, cold astrophysical environments, such as molecular clouds or protostellar clouds as well at the surface of outer solar system bodies. The measurements were performed at the heavy ion accelerator GANIL (Grand Accelerateur National d'Ions Lourds) in Caen, France. The gas samples were deposited onto a CsI substrate at 13 K and 80 K. In situ analysis was performed by a Fourier transform infrared (FTIR) spectrometer at different fluences. Radiolysis yields of the produced species were quantified. The dissociation cross section at 13 K of both H(2)O and CO(2) is about 3-4 times smaller when O ions are employed. The ice temperature seems to affect differently each species when the same projectile was employed. The formation cross section at 13 K of molecules such as C(18)O, CO (with oxygen from water), and H(2)O(2) increases when Ni ions are employed. The formation of organic compounds seems to be enhanced by the oxygen projectiles and at lower temperatures. In addition, because the organic production at 13 K is at least 4 times higher than the value at 80 K, we also expect that interstellar ices are more organic-rich than the surfaces of outer solar system bodies.