High Temperature Alters Secondary Metabolites and Photosynthetic Efficiency in Heracleum sosnowskyi

Due to global warming, invasive species have spread across the world. We therefore studied the impact of short-term (1 day or 2 days) and longer (7 days) heat stress on photosynthesis and secondary metabolites in Heracleum sosnowskyi, one of the important invasive species in the European Union. H. sosnowskyi leaves exposed to short-term heat stress (35 °C/1 d) showed a decrease in chlorophyll and maximum potential quantum efficiency of photosystem II (Fv/Fm) compared to control, 35 °C/2 d, or 30 °C/7 d treatments. In turn, the high level of lipid peroxidation and increased H₂O₂ accumulation indicated that the 30 °C/7 d stress induced oxidative damage. The contents of xanthotoxin and bergapten were elevated in the 2 d and 7 d treatments, while isopimpinellin was detected only in the heat-stressed plants. Additionally, the levels of free proline and anthocyanins significantly increased in response to high temperature, with a substantially higher increase in the 7 d (30 °C) treatment. The results indicate that the accumulation of proline, anthocyanins, and furanocoumarins, but not of phenolic acids or flavonols, contributes to protection of H. sosnowskyi plants against heat stress. Further studies could focus on the suppression of these metabolites to suppress the spread of this invasive species.     

Gradient piezoelectricity for cracks under an impact load

The flexoelectric effect on elastic waves is investigated in nano-sized cracked structures. The strain gradients are considered in the constitutive equations of a piezoelectric solid for electric displacements and the higher-order stress tensor. The governing equations with the corresponding boundary conditions are derived from the variational principle. The finite element method (FEM) is developed from the principle of virtual work. It is equivalent to the weak-form of derived governing equations in gradient elasticity. The computational method can be applied to analyze general 2D boundary value problems in size-dependent piezoelectric elastic solids with cracks under a dynamic load. The FEM formulation is implemented for strain-gradient piezoelectricity under a dynamic load.     

Soviet VIC Cipher: No Respector of Kerckoff's Principles

In this article, the author demonstrates that cracking the Soviet VIC cipher is possible if one knows the enciphering algorithm. Without this knowledge, the VIC cipher appears to be very strong, and it is almost impossible to crack a single message encrypted with it.     

Computing minimal doubly resolving sets of graphs

In this paper we consider the minimal doubly resolving sets problem (MDRSP) of graphs. We prove that the problem is NP-hard and give its integer linear programming formulation. The problem is solved by a genetic algorithm (GA) that uses binary encoding and standard genetic operators adapted to the problem. Experimental results include three sets of ORLIB test instances: crew scheduling, pseudo-boolean and graph coloring. GA is also tested on theoretically challenging large-scale instances of hypercubes and Hamming graphs. Optimality of GA solutions on smaller size instances has been verified by total enumeration. For several larger instances optimality follows from the existing theoretical results. The GA results for MDRSP of hypercubes are used by a dynamic programming approach to obtain upper bounds for the metric dimension of large hypercubes up to 2⁹⁰$2^{90}$ nodes, that cannot be directly handled by the computer.     

Drawing of self‐reinforced cellulose films

Self‐reinforced cellulose films were prepared by incomplete dissolution of commercial microcrystalline cellulose in LiCl/DMAc solvent and subsequent coagulation of regenerated cellulose in the presence of undissolved microcrystalline cellulose. By drawing in wet conditions and subsequent drying, preferred orientation was introduced into the self‐reinforced cellulose films, resulting in significantly improved tensile strength of up to 430 MPa and modulus of elasticity of up to 33 GPa. A linear relationship was observed between applied draw, and the orientation of cellulose in the films, and the measured elastic modulus and tensile strength, respectively. The optically transparent drawn films significantly surpass the strength and modulus of elasticity of current all‐bio‐based planar materials and may therefore present a bio‐degradable alternative to nonbio‐based materials with similar performance. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2703–2708, 2007     

Positron annihilation and Mössbauer spectroscopy applied to WWER-1000 RPV steels in the frame of IAEA High Ni Co-ordinated Research Programme

Positron annihilation spectroscopy (PAS) and Mössbauer spectroscopy (MS) were applied in the evaluation of the microstructure parameters and degradation processes of nuclear reactor pressure vessel (RPV) steel surveillance specimens. Study was oriented to the material investigation of Russian WWER-1000 steels (15Kh2MNFAA and 12Kh2N2MAA) with high Ni content (1.26 wt% in base metal and 1.7 wt% in weld). For comparison, the WWER-440 weld metal (Sv10KhMFT) without Ni was also measured. Specimens were studied in as-received form, after irradiation in LVR-15 experimental reactor to the neutron fluence F_(E>0.5MeV)=1.47×10²⁴ m⁻² s⁻¹ and after annealing process in vacuum at 475 °C per 2 h. Changes due to different chemical composition and irradiation were registered using MS. Post-irradiation thermal treatment and annealing of defects was well detected by different PAS techniques. Results confirm the hypothesis that Ni affects size (decrease) and distribution (more homogeneous) of the Cu- and P-rich clusters and M_xC_x carbides.     

Atom Location by Channeling-Enhanced Microanalysis (ALCHEMI) Study of Structure of Complex Concentrated Alloys Derived From FeAl Iron Aluminide

Metallurgical and Materials Transactions A - Two sets of alloys derived from FeAl iron aluminide, with the ratio of Fe and Al equal 55:45 and 50:50, respectively, were investigated. The FeAl alloys...     

Superhydrophobic Polyester/Cotton Fabrics Modified by Barrier Discharge Plasma and Organosilanes

In this paper, diffuse coplanar surface barrier discharge plasma at atmospheric pressure has been used for surface modification of polyester/cotton (PESc) fabric, which was subsequently modified by sol–gel process using suitable organofunctional silanes to enhance its hydrophobicity. Modified PESc fabric surfaces were conditioned during the gelling process to obtain the permanent hydrophobicity. The contact angle of water before washing of plasma and sol–gel pretreated PESc fabric was found to be 154° and 151° after standardized washings. It was also demonstrated that the process is applicable at the industrial scale.     

Transparent polycrystalline nanoceramics consisting of triclinic Al2SiO5 kyanite and Al2O3 corundum

Transparent polycrystalline nanoceramics consisting of triclinic Al₂SiO₅ kyanite (91.4 vol%) and Al₂O₃ corundum (8.6 vol%) were fabricated at 10 GPa and 1200‐1400°C. These materials were obtained by direct conversion from Al₂O₃‐SiO₂ glasses fabricated using the aerodynamic levitation technique. The material obtained at 10 GPa and 1200°C shows the highest optical transparency with a real in‐line transmission value of 78% at a wavelength of 645 nm and a sample‐thickness of 0.8 mm. This sample shows equigranular texture with an average grain size of 34 ± 13 nm. The optical transparency increases with decreasing mean grain size of the constituent phases. The relationship between real in‐line transmission and grain size is well explained by a grain‐boundary scattering model based on a classical theory.