Molecular dynamics simulations of oxygen Frenkel pairs in cerium dioxide

Molecular dynamics simulations of oxygen Frenkel pairs (FPs) in cerium dioxide (CeO₂) were carried out in order to understand their kinetic behavior. The results show that an oxygen FP recombine with the vacancy and the interstitial after the vacancy jump preferentially along the 〈1 0 0〉 direction. When multiple oxygen FPs are introduced, the interstitials aggregate into a (1 1 1) plate-like cluster at relatively lower temperature lower than 600 K, while they recombine with vacancies at elevated temperatures higher than 900 K within 10 ps. Molecular mechanics calculations of oxygen FPs on a (1 1 1) plane show that the formation energy per a FP decreases with increase of the number of FPs. The theoretical results are consistent with the transmission electron microscopy observations of formation of 1/9〈1 1 1〉{1 1 1} oxygen interstitial platelets in CeO₂ under electron irradiation.     

Evaluation of the potential of functionalised calcium carbonate as carrier for essential oils with regard to antimicrobial packaging applications

Functionalised calcium carbonates (FCCs) are inorganic mineral-based particles with a high porosity and extended surface area consisting of hydroxyapatite and calcium carbonate crystal structures. Therefore, FCCs have a high potential to be used as a carrier for active substances such as essential oils (EOs), which are well known for their antimicrobial activities, and control their release in antimicrobial packaging applications. In this study, different EOs were loaded on FCCs, and their antimicrobial activities were studied against Listeria innocua in in vitro tests and in food tests using sliced cooked chicken breast. FCCs loaded with thyme or oregano EO (10 wt%) showed the highest reduction in microbial load in in vitro tests at 37°C (≥8.6 log cfu/filter) as well as at 7°C after 6 days (≥7.0 log cfu/filter for thyme EO and 6.5 log cfu/filter for oregano EO). However, in food tests, FCC loaded with either EO did not show any significant antimicrobial activity. FCCs loaded with cinnamon or rosemary EO (10 wt%) did not show any significant antimicrobial activity in in vitro tests. On the other hand, they showed a significant reduction in microbial load (1.7 log cfu/g for cinnamon and 2 log cfu/g for rosemary) in food tests. Differences in antimicrobial activities in in vitro and food tests are probably due to the interaction of the components of the EOs and the components of the food such as fat and proteins.     

Metamodel-assisted optimization based on multiple kernel regression for mixed variables

While studies in metamodel-assisted optimization predominantly involve continuous variables, this paper explores the additional presence of categorical data, representing for instance the choice of a material or the type of connection. The common approach consisting in mapping them onto integers might lead to inconsistencies or poor approximation results. Therefore, an investigation of the best coding is necessary; however, to build accurate and flexible metamodels, a special attention should also be devoted to the treatment of the distinct nature of the variables involved. Consequently, a multiple kernel regression methodology is proposed, since it allows for selecting separate kernel functions with respect to the variable type. The validation of the advocated approach is carried out on six analytical benchmark test cases and on the structural responses of a rigid frame. In all cases, better performances are obtained by multiple kernel regression with respect to its single kernel counterpart, thereby demonstrating the potential offered by this approach, especially in combination with dummy coding. Finally, multi-objective surrogate-based optimization is performed on the rigid frame example, firstly to illustrate the benefit of dealing with mixed variables for structural design, then to show the reduction in terms of finite element simulations obtained thanks to the metamodels.     

Efficient Inhibition of Telomerase by Nickel–Salophen Complexes

Four nickel(II)–salophen complexes containing alkyl‐imidazolium chains connected at the ortho or meta positions were prepared: N,N′‐bis(2‐hydroxy‐4‐methyl‐3H‐imidazol‐1‐iumbenzylideneamino)phenylenediamine ( 1 ), N,N′‐bis(2‐hydroxy‐3‐methyl‐3H‐imidazol‐1‐iumbenzylideneamino)phenylenediamine ( 2 ), N,N′‐bis(2‐hydroxy‐3‐methyl‐3H‐imidazol‐1‐iumbenzylideneamino)methyl‐3H‐imidazol‐1‐iumphenylenediamine ( 3 ), and N,N′‐bis(2‐hydroxy‐4‐methyl‐3H‐imidazol‐1‐iumbenzylideneamino)methyl‐3H‐imidazol‐1‐iumphenylenediamine ( 4 ). They protect G‐quadruplex DNA (G₄‐DNA) against thermal denaturation and show K_A values in the range of 7.4×10⁵ to 4×10⁷ m ^?1 for G₄‐DNA models. Complex 4 exhibits an IC₅₀ value of 70 nm for telomerase inhibition.     

Dispersion of multiwalled carbon nanotubes in water by lignin

Multiwalled carbon nanotubes (MWCNT) can be stably dispersed in water with small amount of lignin. One-step dispersion in the 20.0 g/L concentration range is achieved at room temperature with excellent electrical properties of MWCNT. Lignin is depicted to act as an anti-static agent.     

Effect of household and industrial processing on levels of five pesticide residues and two degradation products in spinach

Spinach (Spinacia oleracea) was sprayed with four fungicides (boscalid, mancozeb, iprodione and propamocarb) and one insecticide (deltamethrin) to quantify the effect of household and industrial processing on the pesticide residues. To ensure sufficiently high levels of residues, the most concentrated formulations were applied pursuant to Good Agricultural Practices (GAPs). The subsequent processing conditions were established in accordance with industrial practice corresponding as closely as possible to the actual conditions that are normally used in practice. The effects of household and industrial processing on the levels of the five pesticide residues and the two degradation products were quantified. Washing with tap water reduced residues by 10-50%. The blanching step allowed decreasing the concentration of residues for the 5 pesticides by 10-70%. It is the most effective step to remove pesticide residues from spinach. The presence of heat in combination with a large quantity of water enhanced the elimination of residues. Microwave cooking hardly reduced residues (up to 39%) whereas in-pack sterilization resulted in a decrease of pesticide residues up to 99%. The cumulative loss in concentration varied between 50 and 95% for the pesticide residues, except for deltamethrin. Degradation products were also investigated in this study. Sterilization produced the most degradation products (namely 3,5-dichloroaniline from iprodione and ethylenethiourea from mancozeb). That can be attributed to heat-induced hydrolysis of mancozeb and iprodione, respectively. Most of the processing factors could be explained in terms of water solubility, the log-octanol-water-partitioning coefficients and the systemic properties of the studied pesticides.     

Comparative study of free and glycoconjugated volatile compounds of three banana cultivars from French West Indies: Cavendish,Frayssinette and Plantain

Free and glycoconjugated volatile composition of three bananas from cultivars of Musa sp. grown in the French West Indies (FWI): Cavendish, Frayssinette and Plantain were investigated. They were extracted from the pulp of bananas thanks to an accelerated solvent extraction method for the free volatile compounds. Glycosides were isolated from aqueous extracts then aglycons were obtained after enzymatic hydrolysis of glycosidic extracts. Free volatile compounds and aglycons were analysed by GC–MS. The main volatile compounds found in Cavendish banana were (E)-2-hexenal and acetoin, in Plantain: (E)-2-hexenal and hexanal, and in Frayssinette: 2,3-butanediol and two diastereomer solerols. The most abundant of aglycons were 3-methyl-butanol, 3-methyl-butanoic acid, solerol (two disatereoisomers) and acetovanillone. This compound, rarely identified in fruits, is detected for the first time in glycoconjugated volatile compounds of fruits. The abundance of these two isomers in the extracts of Frayssinette seemed to be characteristic of this variety of banana.