Evaluation of ozonation as a method for mycotoxins degradation in malting wheat grains

The influence of ozone (O3) gas on reducing the contamination with Fusarium mycotoxins in malting wheat grains was investigated. Ultra-high performance liquid chromatography coupled to triple quadrupole tandem mass spectrometry (UHPLC-QqQ-MS/MS) and Orbitrap high resolution mass spectrometry (UHPLC-Orbitrap-HRMS) were used to determine mycotoxins in wheat grains before and 40 to 130 min after the exposure to 20 mg/l O3. Pearson’s analysis (R2=0.96-0.98) showed a good correlation between the performance efficiency of both mass spectrometry quantification techniques. The concentrations of determined mycotoxins (zearalenone (ZEA): 19.5-459 µg/kg, deoxynivalenol (DON): 3,370-4,620 µg/kg, T-2 toxin: 19.5-35.4 µg/kg, and HT-2 toxin: 258-819 µg/kg) decreased notably, depending on the duration of contact with ozone. A notable elimination of ZEA, HT-2, and T-2 in wheat grain was observed: the content of these compounds was reduced on average by 58.6, 64.6, and 62%, respectively, already after 40 min of ozonation. The effect was less pronounced in the case of DON, for which the average degradation rate reached the maximum of only 25% after 130 min exposure. We conclude that ozonation for up to 130 min was effective for reducing the content of most mycotoxins determined in this study, except for DON, in contaminated grains to concentrations below the acceptable maximum levels in wheat in accordance to the EU regulations.

Dependence of single-walled carbon nanotube adsorption kinetics on temperature and binding energy

We present results for the isothermal adsorption kinetics of methane, hydrogen, and tetrafluoromethane on closed-ended single-walled carbon nanotubes. In these experiments, we monitor the pressure decrease as a function of time as equilibrium is approached, after a dose of gas is added to the cell containing the nanotubes. The measurements were performed at different fractional coverages limited to the first layer. The results indicate that, for a given coverage and temperature, the equilibration time is an increasing function of E/(k(B)T), where E is the binding energy of the adsorbate and k(B)T is the thermal energy. These findings are consistent with recent theoretical predictions and computer simulations results that we use to interpret the experimental measurements.

Argon adsorption on Cu3(benzene-1,3,5-tricarboxylate)2(H2O)3 metal-organic framework

Using volumetric adsorption techniques, we have measured the adsorption of argon on Cu3(BTC)2(H2O)3, (BTC = benzene-1,3,5-tricarboxylate), a microporous metal-organic framework structure, at temperatures between 66 and 143 K. In addition to the experiments, we have used Grand Canonical Monte Carlo simulations to calculate the adsorption isotherm of argon at 87 K. Our experimental and theoretical results are compared to those of previous studies. The experiments were performed using a high density of points, allowing us to obtain, in detail, the isosteric heat's coverage dependence. Our values from the simulations are in reasonable agreement with those obtained in the experiments.

Higher coverage gas adsorption on the surface of carbon nanotubes: evidence for a possible new phase in the second layer

We present adsorption isotherm results for Ne, CH4, and Xe on bundles of close-ended single-wall carbon nanotubes, for coverages above the completion of the first layer. We find a small, sharp, substep present in the second-layer data for Ne and CH4, and a weaker feature, that produces an isothermal compressibility peak, for Xe. The size and location of the feature allows its tentative identification as a new, second-layer, one-dimensional phase, in which the atoms sit atop high binding energy sites in the second layer.