EXTENDED VALIDATION OF DYNAMIC IRREVERSIBLE THERMOPORATION: A NOVEL THERMAL PROCESS FOR MICROBIAL INACTIVATION

A novel thermal treatment for microorganism inactivation, characterized by a very rapid temperature increase (up to 30C/s) and a low final temperature (up to 65C) maintained for a relatively short holding time, has been recently presented and tested by the authors, showing microbial load reduction greater than 5 log units against several common bacteria and yeasts. With the aim of extending the possible use of the new thermal treatment to a wider microorganisms class, in this work the dynamic irreversible thermoporation (DIT) treatment was further tested on a well-known thermoresistant strain, the Enterococcus hirae: The results of these new experimental tests confirmed the reliability of t…

Extended Validation of Dynamic Irreversible Thermoporation: A Novel Thermal Process for Microbial Inactivation

A novel thermal treatment for microorganism inactivation, characterized by a very rapid temperature increase (up to 30°C/s) and a low final temperature (up to 65°C) maintained for a relatively short holding time, has been recently presented and tested by the authors, showing microbial load reduction greater than 5 log units against several common bacteria and yeasts. With the aim of extending the possible use of the new thermal treatment to a wider microorganisms class, in this work the dynamic irreversible thermoporation (DIT) treatment was further tested on a well-known thermoresistant strain, the Enterococcus hirae: The results of these new experimental tests confirmed the reliability of…

Butene Isomerization and Double-Bond Migration on the H-ZSM-5 Outer Surface: A Density Functional Theory Study

Isomerization of trans-but-2-ene to cis-but-2-ene and double bond migration of trans-but-2-ene to but-1-ene have been investigated by means of density functional theory calculations on a suitable model of H-ZSM-5 surface. The study has been afforded on outer surface sites by considering the hydroxyl group of either a SiO2(OH)2 or a AlO2H(OH)2 moiety. On these outer surface sites, one alkoxide species occurs as a stable intermediate both along the isomerization and double bond migration pathways. The latter process could also occur via a single-step mechanism, which involves a six-center transition state. The energy barriers of the outer surface processes above do not take any advantage by t…

Molecular-Level Characterization of Heterogeneous Catalytic Systems by Algorithmic Time Dependent Monte Carlo

Monte Carlo algorithms and codes, used to study heterogeneous catalytic systems in the frame of the computational section of the NANOCAT project, are presented along with some exemplifying applications and results. In particular, time dependent Monte Carlo methods supported by high level quantum chemical information employed in the field of heterogeneous catalysis are focused. Technical details of the present algorithmic Monte Carlo development as well as possible evolution aimed at a deeper interrelationship of quantum and stochastic methods are discussed, pointing to two different aspects: the thermal-effect involvement and the three-dimensional catalytic matrix simulation. As topical app…

Catalytic Supported System Modelled by Computational Approaches

Experimental Evaluation of a New Thermal Process for Microorganisms Inactivation

A new thermal process for the inactivation of microorganisms in beverages has been studied and is presented in this paper. The treatment, not yet studied in the scientific literature, mainly consists of a thermal shock characterized by temperature increases up to 30°C/s, with final temperatures up to 65°C. This study presents the first experimental results obtained by the application of the new thermal treatment, with different combinations of the process parameters (rate of temperature rise, final temperature and holding time), on separate suspensions of Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Listeria innocua and Candida albicans. The required rapid temperature in…

Dielectric Characterization of Fruit Nectars at Low RF Frequencies

Dielectric properties of apple, apricot, peach, and pear nectars were studied in the frequency range from 15 kHz to 30 MHz and the temperature range from 25 to 60 degrees C. Both the relative dielectric constants and the dielectric loss factors decreased by increasing frequency and increased linearly with increasing temperature with values in the order 10(4)-10(2) and 10(5)-10(2), respectively. The power dissipation densities and the power penetration depths were found to increase linearly with temperature. Power dissipation densities remained essentially constant for all the samples while power penetration depths decreased significantly on increasing frequency. The dependence of each of th…

Computational Study of the Hydrogenolysis of Hydroxymatairesinol to Matairesinol

Structural and Kinetic DFT Characterization of Materials to Rationalize Catalytic Performance

This review shortly discusses recent results obtained by the application of density functional theory for the calculations of the adsorption and diffusion properties of small molecules and their reactivity on heterogenous catalytic systems, in the ambit of the Nanocat project. Particular focus has been devoted to palladium catalysts, either in atomic or small cluster form. Some protocols have been tested to obtain efficient ways able to treat the electronic and geometric influence of supports like zeolites and carbon nanotubes on the catalytic properties of palladium. The hydroisomerization of cis-but-2-ene is discussed as model reaction on supported and unsupported Pd clusters. Some prelim…

Catalysis in confined spaces: computational study of H-ZSM5 zeolite reactivity

Modeling of catalytic materials: advances in studying different supports

Confined But-2-ene catalytic isomerization inside H-ZSM-5 models: A DFT study

The isomerization of cis-but-2-ene to trans-but-2-ene within a 22T H-ZSM-5 zeolite model, also in the presence of two adsorbed Pd atoms, has been studied by DFT calculations. The results obtained allow us to state that the cis/trans but-2-ene isomerization can easily proceed inside unsupported zeolite cavities. In this case, differently than in the gas phase reaction, the trans-but-2-ene is less stable than the cis-but-2-ene, when adsorbed on the zeolite inner surface. Excluding the adsorption-desorption steps, the isomerization process involves two intermediates and three transition states, whose energy content is always very low with respect to that of reagents and intermediate species. T…