The release of Ag+ confined in the cavities of nanoscale inorganic clusters can be selectively triggered by the Na+ present in solutions or biological media for long-lasting bacteriostasis.

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Product, packaging and vehicle constitute a complex product transport system in logistics. It is very difficult to obtain accurately the dynamic response of a product transport system under the action of environmental vibration and shock. In this paper, product transport system is treated as a two substructure‐coupled system composed of product system (including critical element) and vehicle connected by packaging and its fixing (location pattern, securing, etc.); the inverse substructure method is applied to the analysis of the dynamic characteristics of the system. For verification of the validity of the inverse substructure method for product transport system, a typical lumped mass model is taken as an example for numerical validation. To check out the accuracy of the method, we completed the experiment, and the predicted substructure‐level frequency response functions are in overall agreement with those measured. The sensitivity of the method to measurement error is also made. To study the influences of the product parameters, packaging and its fixing, we investigated the effects of the coupling stiffness, mass ratio, frequency parameter ratio and damping on the dynamic response of critical element. Reducing the coupling static stiffness of product–vehicle interface can effectively lower the response of critical element, especially when the coupling stiffness is less than the stiffness of product and vehicle. Copyright © 2011 John Wiley & Sons, Ltd.

This study investigates the release of thymol, cinnamaldehyde and vanillin from soy protein isolate (SPI) films into olive oil. The SPI‐based films were casted with thymol, cinnamaldehyde and vanillin to obtain antimicrobial packaging films. The release of thymol, cinnamaldehyde and vanillin from the SPI films into olive oil at temperatures of 5°C, 20°C, 40°C and 60°C was determined by high‐performance liquid chromatography. The partition coefficients of thymol, cinnamaldehyde and vanillin between the SPI film and the olive oil were obtained. They decreased linearly with the increase of temperature. The diffusion coefficients of thymol, cinnamaldehyde and vanillin were determined by fitting the mathematical model to the experimental data. The Arrhennius equation could adequately describe the relationship between the temperature and the diffusion coefficients of thymol, cinnamaldehyde and vanillin, respectively. The activation energies for the release of thymol, cinnamaldehyde and vanillin were obtained, and they were respectively 55.92, 57.34 and 18.32 kJ mol−1. Copyright © 2011 John Wiley & Sons, Ltd.

Understanding the diffusion of migrants in polyethylene terephthalate (PET) and calculating the diffusion coeffi cients are very important for migration research. In this study, the diffusion coeffi cients of 13 kinds of small molecules with molecular weights ranging from 32 to 339 g/mol in amorphous PET are calculated based on molecular dynamics (MD) simulation. By comparison of diffusion coeffi cients simulated by MD simulation techniques, predicted by the Piringer model and by experiments, the accuracy of the Piringer model and MD simulation techniques for the estimation of diffusion coeffi cients of migrants in PET is evaluated. The MD simulation shows that D simu is very close to D exp , within one order of magnitude of the experimental diffusion coeffi cients except for a few samples. The possible reasons for the differences among D simu , D pred and D exp are analysed from the molecular weight and temperature. The results show that the Piringer-model-predicted values at high temperatures overestimate signifi cantly higher than that at lower temperatures. The activation energy is calculated by the Arrhenius equation, which shows the relationship between diffusion coeffi cient and temperature. It is shown that the MD simulation yields acceptable activation energy. The study suggests that MD simulation may be a useful approach to calculate the diffusion coeffi cients of small molecules in PET.

In this study, the low methoxyl pectin-carboxymethyl cellulose-based montmorillonite (LMP-CMC-MMT, LCM) nanocomposite films with nine ratios of LMP:CMC (from 10:0 to 0:10) and different MMT contents (1-8 wt%) were prepared. The mechanical properties, colour, opacity and water vapour permeability (WVP) of composite films were investigated. The maximum of tensile strength (TS) of composite films was 39.85 AE 2.51 MPa at LMP:CMC ratio of 4:6 and 4 wt% MMT (LCM47), which indicated the formation of hydrogen bonds between MMT and LMP-CMC. The reduction of WVP of the LCM47 composite film was 333% of that of the CMC film due to the tortuous path caused by MMT incorporation. LCM composite films had the higher b*-and DE*-values and lower L*-values in comparison with LMP-CMC (LC) composite films. The LCM composite films showed a decrease in transparency as MMT content increased.

This study investigates the determination and migration of stabilizers and plasticizers from polyethylene terephthalate (PET). Two methods [ultrasonic extraction with dichloromethane or methanol and total dissolution with phenol/tetrachloroethane (m:m/1:1)] for pre-concentration of additives in PET material were performed. The diffusion of these additives from PET was evaluated by immersing in deionized water, acetic acid 3% (w/v), ethanol 20% (v/v), ethanol 50% (v/v) and isooctane at 20, 40, 55 and 70°C, respectively. The amount of additives in PET and food simulants was quantified by high-performance liquid chromatography-photodiode array detector (HPLC-PDA). The optimized HPLC method showed high correlation coefficients (R ≥ 0.9993), good precision, accuracy and reproducibility. Experimental diffusion coefficients (DP) were calculated according to a mathematical model based on Fick's second law, and the DP values of considered compounds ranged from 9.8 × 10(-15) to 1.4 × 10(-8) cm(2) s(-1) The experimental DP values were also compared with that predicted by currently used diffusion models. In addition, the effect of temperature on the diffusion rate was assessed. The effect of temperature on the diffusion coefficients followed an Arrhenius-type model with active energies ranged from 40.4 to 113.8 kJ mol(-1) for the target compounds.

Molecular dynamics (MD) simulation was used to investigate the diffusion behaviour of five additives [2,6-di-tert-butyl-4-methylphenol (BHT), 2-(2-Hydroxy-5-methylphenyl)benzotriazole (UV-P), 2,4-Ditert-butyl-6-(5-chloro-2H-benzotriazol-2-yl) phenol(UV-327), 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3tetramethylbutyl) phenol (UV-329) and 2-hydroxy-4-(octyloxy)benzophenone (UV-531)] in polypropylene (PP) at the temperature of 293, 313 and 343 K. The diffusion coefficients were determined through Einstein relation connecting the data of mean square displacement at different times. The simulated diffusion coefficients were compared with that predicted by Piringer model and by experiments to evaluate the accuracy of MD simulation technique for estimating the diffusion coefficients of chemical additives in PP. Results showed that the simulated values were generally within one order of magnitude of the corresponding experimental values. The activation energies of additives were calculated by plotting the logarithm of diffusion coefficients versus the reciprocal of temperature according to Arrhenius equation. The activation energies calculated from MD simulation were also more closely to experimental values. Subsequently, the diffusion mechanism of additives inside PP was tentatively explored by analysing the interaction energy between diffusion molecules and polymer, free volume, molecular weight, size and shape, and the mobility of polymer chain. The movements of the additives in PP cell models at different simulation time suggested that for a long time, the additive molecules vibrate rather than hopping until they find the equal or larger transport channel to diffuse. It is demonstrated that the MD simulation may be a useful approach for predicting the microstructure and the diffusion coefficient of chemical additive with large molecular size and complex structure in polypropylene.