Performance of an active paper based on cinnamon essential oil in mushrooms quality.

The antioxidant capacity of two active papers (based on solid and emulsion paraffin) with cinnamon essential oil was studied. Mushroom samples were introduced in macroperforated PET trays covered with the active papers, and weight loss and browning monitored for 9 days. The antioxidant capacity of the different papers was evaluated based on scavenging 1,1-diphenyl-2-picryl-hydrazyl (DPPH) and tyrosinase inhibition kinetics, and the release of aromatic volatile oils was determined by HSPME-GC-MS. Differences in performance were observed: the active papers were more efficient at avoiding weight loss and mushroom browning when compared to the non-active paraffin-based papers. The efficiency increased when the bottom and walls of the trays were covered rather than the bottom alone. Better results were observed when cinnamon was incorporated as emulsion paraffin instead of a solid.

Study of the surface chemistry of modified carbon nanofibers by oxidation treatments in liquid phase.

Carbon nanofibers (CNF) were grown by thermocatalytic decomposition of methane. Their texture and surface chemistry were modified by different oxidation treatments with HNO3 at different concentrations or a mixture of HNO3-H2SO4 to optimise their ability of dispersing active metal particles, because this material will be used as electrocatalytic support for polymeric electrolyte fuel cells. The effect of liquid phase oxidation on the surface chemistry and the textural properties of the CNF was studied by temperature programmed desorption (TPD), scanning electron microscopy (SEM) and N2-physisorption. Moreover, their thermal stability was studied by temperature programmed oxidation (TPO). During oxidation treatments functional groups were created and their number was function of the oxidation treatment conditions. Results indicated that an increase in severity of the oxidation treatment produces an increase in the number of surface oxygen groups and in the thermal stability. However, a very severe treatment can destroy partially the structure of carbon nanofibers.

Characterization of carbon nanofibers grown over Ni and Ni-cu catalysts.

Carbon nanofibers were obtained by thermo-catalytic decomposition of methane at 700 degrees C over Ni and Ni-Cu catalysts prepared by different methods (co-precipitation, impregnation and fusion) and using either Al or Mg as textural promoter. Characterization of the carbon thus obtained was performed by N2 adsorption isotherms (BET surface area), temperature programmed desorption (TPD), temperature programmed oxidation (TPO), X-ray diffraction, Raman spectrometry, and electron microscopy SEM and TEM. The carbon obtained possesses high crystallinity and poor surface chemistry. The crystallinity is enhanced when using Mg as textural promoter and in the presence of copper. SEM and TEM examinations show that the fibers have fishbone structure and they grow generally from one nickel particle (tip growing) although there are some bidirectional growing. Copper-doping lead to the formation of thicker filaments and promotes the formation of bamboo-like structures. Catalyst particles higher than 100 nm do not promote the formation of nanofibers and the carbon deposits as uniform coatings.

Antimony(V) volatilization with bromide and determination by inductively coupled plasma atomic emission spectrometry.

Antimony(V) is volatilized by reaction with potassium bromide in concentrated sulfuric acid media. After volatilization, the gases can be transported to an inductively coupled plasma spectrometer for atomic emission of antimony and its analytical determination. The influent factors, concentrated sulfuric acid volume, concentration and volume of the potassium bromide aqueous solution and carrier gas flow were investigated and optimized using different alternatives. A detection limit of 48ngml(-1) of Sb was achieved under the optimized conditions with a precision of 7.6% and the calibration graph was linear from 0.10 to 10.0mugml(-1) for a sample injection of 130mul. The study of interferences from common cations and anions revealed a good tolerance for most ions, although there was a significant improvement in Sb(V) volatility when As(III) was present. Furthermore, the As(III) sensitization was only produced with Sb(V) species, while the volatility of the Sb(III) bromide species was unaltered. The method was applied to the determination of Sb in real river waters. The results were checked using alternative atomic spectroscopy methods.