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The nature of the newly proposed two-positron bond in (PsH)2, which is composed of two protons, four electrons and two positrons, is considered in this contribution. The study is done at the multi-component-Hartree-Fock (MC-HF) and the Diffusion Monte Carlo (DMC) levels of theory by comparing ab initio data, analyzing the spatial structure of the DMC wavefunction, and applying the multi-component quantum theory of atoms in molecules and the two-component interacting quantum atoms energy partitioning schemes to the MC-HF wavefunction. The analysis demonstrates that (PsH)2 to a good approximation may be conceived of two slightly perturbed PsH atoms, bonded through a two-positron bond. In contrast to the usual two-electron bonds, the positron exchange phenomenon is marginal in the considered two-positron bond. The main stabilizing mechanism of bonding is a novel type of classical electrostatic interaction between the positrons, which are mainly localized between nuclei, and the surrounding electrons. To emphasize its uniqueness, this mechanism of bonding is proposed to be called gluonic which has also been previously identified as the main deriving mechanism behind formation of the one-positron bond in [H-, e+, H-] . We conclude that the studied two-positron bond should not be classified as a covalent bond and it must be seen as a brand-new type of bond, foreign to the electronic bonding modes discovered so far in the purely electronic systems., Comment: main text plus supporting information

Modified atmosphere packaging and related technologies are increasingly used to extend shelf-life of fresh products. This paper covers the effect of such techniques on increasing shelf life. Salad-cut lettuce was washed in different solutions for a period of 1 min. Then, salad-cut lettuce was packed in modified atmosphere (3–5% CO2, 3–5% O2, 97–95% N2) and stored at 4 °C for 12 days. Quality indicators of packaged lettuce including color, texture, sensory properties, total phenol content and antioxidant activity were analyzed at 1, 3, 6, 9 and 12 days of storage. This study showed that combination of sodium hypochlorite and ascorbic acid was the best treatment to maintain most of the qualitative indicators of lettuce during storage at 4 °C (p

Today, with the growth in application of communication equipment as well as the use of Internet for information exchange, the need for data security and protection is felt more than before. Various methods have been proposed in recent years to realize this goal. One efficient, widely used method is hiding of information within data of insignificant value. An image, due to its large amount of information, may embed different data within, hence providing a decent safety margin for critical data. Three methods, including least significant bit (LSB), discrete wavelet transform (DWT) and singular value decomposition (SVD) were used in this study for image-in-image steganography. Each method has advantages and disadvantages. Advantages of LSB include high capacity and simplicity, however, as for the disadvantages, it is vulnerable against attacks such as cropping, salt and pepper noise, and compression. Therefore, the other two methods, DWT and SVD, which are robust against the mentioned attack, are used as steganography in frequency domain. Among the methods used in this study, SVD least affects the host image, making it more suitable as compared with its other two counterparts.