The electron beam irradiation of collagen in the dry and gel states: The effect of the dose and water content from the primary to the quaternary levels.

The aim of our study was to describe the impact of collagen in the gel and dry state to various doses of electron beam radiation (1, 10 and 25 kGy) which are using for food processing and sterilization. The changes in the chemical compositions (water, amino acids, lipids, glycosaminoglycans) were analyzed and the changes in the structure (triple-helix or ß-sheet, the integrity of the collagen) were assessed. Subsequently, the impact of the applied doses on the mechanical properties, stability in the enzymatic environment, swelling and morphology were determined. The irradiated gels evinced enhanced degrees of cross-linking with only partial degradation. Nevertheless, an increase was observed in their stability manifested via a higher degree of resistance to the enzymatic environment, a reduction in swelling and, in terms of the mechanical behaviour, an approximation to the non-linear behavior of native tissues. In contrast, irradiation in the dry state exerted a somewhat negative impact on the observed properties and was manifested mainly via the scission of the collagen molecule and via a lower degree of stability in the aqueous and enzymatic environments. Neither the chemical composition nor the morphology was affected by irradiation.

Influence of Disinfection Methods on Cinematographic Film.

Microbiological contamination of cinematographic films can cause damage and loss of image information. A large part of the films is made with the base of cellulose triacetate, which has been used from the 1940s until today. Cellulose triacetate is relatively resistant to common organic solvents, but some types of microorganisms can contribute to its faster degradation. In this work, we tested four types of disinfectants suitable for mass disinfection and sufficiently effective against various types of microorganisms. Butanol vapours, a commercial mixture of alcohols (Bacillol® AF), Septonex® (an aqueous solution of [1-(ethoxycarbonyl)pentadecyl] trimethylammonium bromide) and ethylene oxide applied as a gas mixed with carbon dioxide were tested. Samples of a commercial film made of cellulose triacetate were disinfected. The samples were aged for 56 days at 70 °C and 55% RH. Changes in optical, mechanical and chemical properties were studied. None of the disinfectants affected the change in the degree of substitution. For samples disinfected with Bacillol® AF (alcohol mixture), part of the plasticiser (triphenyl phosphate) was extracted and the intrinsic viscosity of the cellulose triacetate solution was reduced after ageing. A slight decrease in intrinsic viscosity also occurred after disinfection with ethylene oxide. Compared to the non-disinfected samples, butanol vapours and Septonex® appear to be the most gentle disinfectants for the cellulose triacetate film base, within the studied parameters.

Evaluation of Permulgin 3274 as a Material for the Conservation of Beeswax Seals.

When treating historical beeswax seals, it seems a natural choice to use materials as similar to the original as possible. The properties of analogous recent materials, however, differ from those of the aged ones, not to mention the fact that the exact composition of the particular sealing wax is usually uncertain. In order to obtain the material of desired properties, recent beeswax is often combined with various additives, including petroleum waxes, or even replaced by mixtures based solely on these products. Within this study, the relevant properties of Permulgin 3274, a ceresin-type wax, were compared with the characteristics of recent and historical beeswaxes. The aim was to evaluate its advantages and limitations, in terms of its possible use for the conservation of beeswax seals. The properties studied were comprised of the chemical composition, thermal properties, mechanical properties, possibilities of colour adjustment and ageing properties. Permulgin 3274's workability was evaluated by conservators from the National Archives in Prague. The results indicate that, from the technological point of view, Permulgin 3274 could be considered a welcome alternative to the use of traditional conservation mixtures.

CO2/CH4 and H2/CH4 Gas Separation Performance of CTA-TNT@CNT Hybrid Mixed Matrix Membranes.

This study explored the underlying synergy between titanium dioxide nanotube (TNT) and carbon nanotube (CNT) hybrid fillers in cellulose triacetate (CTA)-based mixed matrix membranes (MMMs) for natural gas purification. The CNT@TNT hybrid nanofillers were blended with CTA polymer and cast as a thin film by a facile casting technique, after which they were used for single gas separation. The hybrid filler-based membrane depicted a higher CO2 uptake affinity than the single filler (CNT/TNT)-based membrane. The gas separation results indicate that the hybrid fillers (TNT@CNT) are strongly selective for CO2 over CH4 and H2 over CH4. The increment in the CO2/CH4 and H2/CH4 selectivities compared to the pristine CTA membrane was 42.98 from 25.08 and 48.43 from 36.58, respectively. Similarly, the CO2 and H2 permeability of the CTA-TNT@CNT membrane increased by six- and five-fold, respectively, compared to the pristine CTA membrane. Such significant improvements in CO2/CH4 and H2/CH4 separation performance and thermal and mechanical properties suggest a feasible and practical approach for potential biogas upgrading and natural gas purification.

CeO2-Blended Cellulose Triacetate Mixed-Matrix Membranes for Selective CO2 Separation.

Due to the high affinity of ceria (CeO2) towards carbon dioxide (CO2) and the high thermal and mechanical properties of cellulose triacetate (CTA) polymer, mixed-matrix CTA-CeO2 membranes were fabricated. A facile solution-casting method was used for the fabrication process. CeO2 nanoparticles at concentrations of 0.32, 0.64 and 0.9 wt.% were incorporated into the CTA matrix. The physico-chemical properties of the membranes were evaluated by SEM-EDS, XRD, FTIR, TGA, DSC and strain-stress analysis. Gas sorption and permeation affinity were evaluated using different single gases. The CTA-CeO2 (0.64) membrane matrix showed a high affinity towards CO2 sorption. Almost complete saturation of CeO2 nanoparticles with CO2 was observed, even at low pressure. Embedding CeO2 nanoparticles led to increased gas permeability compared to pristine CTA. The highest gas permeabilities were achieved with 0.64 wt.%, with a threefold increase in CO2 permeability as compared to pristine CTA membranes. Unwanted aggregation of the filler nanoparticles was observed at a 0.9 wt.% concentration of CeO2 and was reflected in decreased gas permeability compared to lower filler loadings with homogenous filler distributions. The determined gas selectivity was in the order CO2/CH4 > CO2/N2 > O2/N2 > H2/CO2 and suggests the potential of CTA-CeO2 membranes for CO2 separation in flue/biogas applications.

Evaluation of Second-Generation Lipophosphonoxins as Antimicrobial Additives in Bone Cement.

Successful surgeries involving orthopedic implants depend on the avoidance of biofilm development on the implant surface during the early postoperative period. Here, we investigate the potential of novel antibacterial compounds-second-generation lipophosphonoxins (LPPOs II)-as additives to surgical bone cements. We demonstrate (i) excellent thermostability of LPPOs II, which is essential to withstand elevated temperatures during exothermic cement polymerization; (ii) unchanged tensile strength and elongation at the break properties of the composite cements containing LPPOs II compared to cements without additives; (iii) convenient elution kinetics on the order of days; and (iv) the strong antibiofilm activity of the LPPO II-loaded cements even against bacteria resistant to the medicinally utilized antibiotic, gentamicin. Thus, LPPOs II display promising potential as antimicrobial additives to surgical bone cements.