Cold Plasma Treatment of Biodegradable films and smart packaging

Cold plasma is an emerging technology offering many potential applications for food packaging. While it was originally developed to increase the surface energy of polymers, enhancing their adhesion and printability, it has recently emerged as a powerful tool for surface sterilisation of both food and food packaging materials. The food packaging industry is still dominated by petroleum derived polymers but in the past few decades there has been significant interest in the development of environment friendly, biodegradable green polymers. In this study, the interaction and effects of cold plasma with biopolymer based packaging materials (polylactic acid, zein, sodium caseinate, starch, chitosan and gelatin) and its potential for active and intelligent packaging was investigated. DBD (Dielectric Barrier Discharge) plasma increased the surface roughness of all the treated polymers films. DBD plasma treatments did not induce significant changes in the thermal profile of the polymers, but significant increases in the initial degradation temperature and maximum degradation temperature was observed for poly(lactic acid) and starch. DBD plasma also increased the equilibrium moisture content of both protein films: zein and sodium caseinate, but no significant increases in the water vapour and oxygen permeability was noticed for any of the films. An increase in overall migration was observed in PLA for various food simulants however they were below the EU regulatory limits. Plasma treatment increased the polar component of the total surface energy of all the polymers. The increase in the O/C atomic ratio shows the formation of new oxygen-containing polar groups on the film surface of the plasma treated films. Plasma treatments of both zein and sodium caseinate film lead to a change in the protein conformation which was confirmed by X-ray diffraction and Fourier transform infrared spectroscopy. Plasma treatment of antimicrobial films (zein and chitosan) also increased their surface roughness. A significant increase in the diffusion coefficient was observed which lead to an accelerated release of the active compound into the food simulant. Phosphorescent optochemical oxygen sensors (Optech™ and PP based) were also evaluated for compatibility with DBD in-package plasma treatment under different gaseous environments. Both sensors worked well under the modified atmospheric condition (devoid of any oxygen) during plasma treatment. However, the PP based sensor was found to be largely degraded after plasma treatment when packed under atmospheric air. Optech™ sensors were found to be compatible with the plasma treatment under both gaseous environment tested, although, a re-calibration was required for sensor accuracy

Impact of Nuclear Deformation on Neutron Dripline Prediction: A Study of Mg Isotopes

We have employed the relativistic Hartree-Bogoliubov (RHB) model with density-dependent meson-exchange interaction and separable pairing to investigate neutron dripline mechanisms for heavy Mg isotopes. In the present study, 40Mg is predicted to be dripline nuclei. The calculations are carried out by taking axial deformation into account. An investigation of shape transition is also done for even-even 32-42Mg isotopes. Our prediction for neutron dripline for 40Mg is consistent with some recent studies

Characterization of Polylactic Acid Films for Food Packaging as Affected by Dielectric Barrier Discharge Atmospheric Plasma

Dielectric barrier discharge (DBD) air plasma is a novel technique for in-package decontamination of food, but it has not been yet applied to the packaging material. Characterization of commercial polylactic acid (PLA) films was done after in-package DBD plasma treatment at different voltage and treatment time to evaluate its suitability as food packaging material. DBD plasma increased the roughness of PLA film mainly at the site in contact with high voltage electrode at both the voltage levels of 70 and 80 kV. DBD plasma treatments did not induce any change in the glass transition temperature, but significant increase in the initial degradation temperature and maximum degradation temperature was observed. DBD plasma treatment did not adversely affect the oxygen and water vapor permeability of PLA. A very limited overall migration was observed in different food simulants and was much below the regulatory limits

Deformation Effect on Proton Bubble Structure in N = 28 Isotones

Purpose: To study the effect of nuclear deformation on proton bubble structure of N = 28 isotones and and compare it with the spherical limits. The reduction of depletion fraction due to deformation can be explained by studying the relative differences in the central densities.Methods: In this work, we have employed relativistic Hartree-Bogoliubov (RHB) model withdensity-dependent meson-exchange (DD-ME2) interaction and separable pairing interaction. We have performed axially constrained calculations to investigate the deformed proton bubble structure in 40Mg, 42Si, 44S, and 46Ar, isotones of N = 28 shell closure.Results: We have observed that the nuclear deformation play againsts the formation of bubble structure. In the spherical limits, the isotones of N = 28 shell closure have pronounced bubble structure with large value of depletion fraction. But, the increase in deformation leads to the disappearance of bubble structure. The internal densities in deformed nuclei are found to increase with deformation which can be related to the decrease in depletion fraction.Conclusion: By using RHB model, we have investigated the ground state and proton bubble structure of N = 28 isotones. In 44S, and 46Ar, the 2s1/21d3/2 states get inverted due to the weakning of spin-orbit strength. Due to strong dynamical correlations, arising from deformation, the central depletion of proton density is greatly affected in these isotones. The decrease in depletion fraction can be related to increase in the internal density due to deformatio

Zein film: Effects of Dielectric Barrier Discharge Atmospheric Cold Plasma

Dielectric barrier discharge atmospheric plasma is a novel non-thermal technology for the food and packaging industry. The effects of dielectric barrier discharge plasma on the surface, structural, thermal and moisture sorption properties of edible zein films have been examined. Plasma treatment increased the surface roughness and equillibrium moisture content of the zein film in a direct relationship with the applied voltage level. No significant difference in the thermal stability of the zein film is also observed after plasma treatment. Dielectric barrier discharge plasma treatments of zein film lead to a change in the protein conformation which is confirmed by X-ray diffraction and Fourier transform Infrared spectroscopy. The evaluation of films modifications by plasma discharge will contribute to enhance the in-package decontamination studies of food products by plasma

Nuclear shape evolution and shape coexistence in Zr and Mo isotopes

The phenomena of shape evolution and shape coexistence in even-even $^{88-126}$Zr and $^{88-126}$Mo isotopes is studied by employing covariant density functional theory (CDFT) with density-dependent point coupling parameter sets DD-PCX and DD-PC1, and with separable pairing interaction. The results for rms deviation in binding energies, two-neutron separation energy, the differential variation of two-neutron separation energy, and rms charge radii, as a function of neutron number, are presented and compared with available experimental data. In addition to the oblate-prolate shape coexistence in $^{96-110}$Zr isotopes, the correlation between shape transition and discontinuity in the observables are also examined. A smooth trend of charge radii in Mo isotopes is found to be due to the manifestation of triaxiality softness. The observed oblate and prolate minima are related to the low single-particle energy level density around the Fermi level of neutron and proton respectively. The present calculations also predict a deformed bubble structure in $^{100}$Zr isotope.Comment: this preprint contains incomplete data and some mistake

In-package Nonthermal Plasma Degradation of Pesticides on Fresh Produce

In-package nonthermal plasma (NTP) technology is a novel technology for the decontamination of foods and biological materials. This study presents the first report on the potential of the technology for the degradation of pesticide residues. A cocktail of pesticides, namely Azoxystrobin, Cyprodinil, Fludioxonil and Pyriproxyfen was tested on strawberries. The concentrations of these pesticides were monitored in priori and post- plasma treatment using GC-MS/MS. An applied voltage and time dependent degradation of the pesticides was observed for treatment voltages of 60, 70 and 80 kV and treatment durations ranging from 1 to 5 min, followed by 24 h in-pack storage. The electrical characterisation revealed the operation of the discharge in a stable filamentary regime. The discharge was found to generate reactive oxygen and excited nitrogen species as observed by optical emission spectroscopy

Relativistic Mean Field Model parameterizations in the light of GW170817, GW190814, and PSR J0740 + 6620

Three parameterizations DOPS1, DOPS2, and DOPS3 (named after the Department of Physics Shimla) of the Relativistic Mean Field (RMF) model have been proposed with the inclusion of all possible self and mixed interactions between the scalar-isoscalar (\sigma), vector-isoscalar (\omega) and vector-isovector (\rho) mesons up to quartic order. The generated parameter sets are in harmony with the finite and bulk nuclear matter properties. A set of Equations of State (EOSs) composed of pure hadronic (nucleonic) matter and nucleonic with quark matter (hybrid EOSs) for superdense hadron-quark matter in \beta-equilibrium is obtained. The quark matter phase is calculated by using the three-flavor Nambu-Jona-Lasinio (NJL) model. The maximum mass of a non-rotating neutron star with DOPS1 parameterization is found to be around 2.6 M$\odot$ for the pure nucleonic matter which satisfies the recent gravitational wave analysis of GW190814 Abbott et al.,(2020) with possible maximum mass constraint indicating that the secondary component of GW190814 could be a non-rotating heaviest neutron star composed of pure nucleonic matter. EOSs computed with the DOPS2 and DOPS3 parameterizations satisfy the X-Ray observational data and the recent observations of GW170817 maximum mass constraint of a stable non-rotating neutron star in the range 2.01 \pm 0.04 - 2.16 \pm 0.03 M\odot and also in good agreement with constraints on mass and radius measurement for PSR J0740+6620 (NICER) Riley et al., L27 (2021)}, Miller et al., (2021). The hybrid EOSs obtained with the NJL model also satisfy astrophysical constraints on the maximum mass of a neutron star from PSR J1614-2230 and Demorest et al., (2010) .We also present the results for dimensionless tidal deformability, ${\Lambda}$ which are consistent with the waveform models analysis of GW170817.Comment: 14 Pages, 10 Figures. arXiv admin note: text overlap with arXiv:2110.07877 by other author

Characterization of Dielectric Barrier Discharge Atmospheric Air Plasma Treated Chitosan Films

Dielectric barrier discharge (DBD) plasma is a novel non-thermal food decontamination technology. The effects of DBD plasma on the surface topography, chemical composition and crystal structure, film hydrophilicity, water vapor permeability and oxygen permeability of chitosan films have been examined. DBD plasma treatment increased the surface roughness of chitosan films with emergence of sharp protuberances. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy spectra confirm a significant increase in the oxygen containing groups in the chitosan film after plasma treatment. Significant increase in the film hydrophilicity was observed after plasma treatment. X-ray diffraction results showed that DBD plasma treatment do not affect the crystal type, although an increase in the structural compactness was observed. No significant change was observed in barrier properties of the chitosan film after DBD plasma treatment. Practical Applications: In-package cold plasma is an innovative technology for the decontamination of foods products and has shown significant potential for industrial applications. This article accesses the suitability of chitosan film to be used with cold plasma treatment. This work characterizes the effect of DBD plasma on the surface, chemical, structural and barrier properties of chitosan film. The work described in this research offers an alternative to the traditional petro-chemical based polymers dominant in food packaging industry where in-package cold plasma can serve as an effective decontamination process avoiding any post-process recontamination or hazards from the package itself

Effects of Cold Plasma on Surface, Thermal and Antimicrobial Release Properties of Chitosan Film

This work aims to analyze the effects of cold atmospheric air plasma treatment of antimicrobial chitosan film with different levels of thymol. Optical characterization of the dielectric barrier discharge showed the generation of reactive nitrogen and oxygen species by the system. A significant increase in the surface roughness was observed after cold plasma treatment of the films. No significant difference was observed in the thermal profile of the plasma-treated films. A significant increase in the thymol diffusion coefficient was observed after the plasma treatment for all the active films