Influence of electron beam irradiation on growth of Phytophthora cinnamomi and its control in substrates

Very extensive production procedure, especially in plants growing under covering, require methods, which would allow quick elimination or substantial reduction of populations of specific pathogens without affecting the growth and development of the cultivated plants. Among soil-borne pathogens, the Phytophthora species are especially dangerous for horticultural plants. In this study, irradiation with electron beam was applied to control Phytophthora cinnamomi. The influence of irradiation dose on the reduction of in vitro growth and the population density of the pathogen in treated peat and its mixture with composted pine bark (1:1), as well as the health of Chamaecyparis lawsoniana and Lavandula angustifolia plants were evaluated. Application of irradiation at a dose of 1.5 kGy completely inhibited the in vitro development of P. cinnamomi. This irradiation effect was connected with the disintegration of the hyphae and spores of the species. Irradiation of peat and its mixture with composted pine bark with 10 kGy resulted in the inhibition of stem base rot development in Ch. lawsoniana. Symptoms of the disease were not observed when the substrates were treated with 15 kGy. In the case of L. angustifolia, stem root rot was not observed on cuttings transplanted to infected peat irradiated at a dose of 10 kGy. Irradiation of the horticultural substrates did not affect plant growth.     

Porous alumina membranes with branched nanopores as templates for fabrication of Y-shaped nanowire arrays

Porous anodic alumina membranes with Y-branched and double-branched nanopores were fabricated by the stepwise reduction of anodizing potential during the second step of anodization carried out in 0.3 M oxalic acid. The process of nanoporous layer formation and influence of anodizing parameters on structural features of as-obtained anodic aluminum oxide (AAO) membranes were discussed in detail. The pore rearrangement process occurring after the potential decrease was investigated on the basis of the current density vs. time curves, and results were correlated with the field-emission scanning electron microscope images of the pore bottoms taken after different anodizing durations. It was found that the reorganization of nanopores begins after 600 and 500 s from the time of the potential reduction to 42 and 30 V and the process seems to be completed after about 900 and 800 s, respectively. The through-hole AAO membranes were used as templates for the fabrication of gold and polystyrene nanowires via electrochemical deposition and simple immersing in the polymer solution, respectively. The arrays of hierarchically branched nanowires were synthesized, and the dimensions of nanowires were consistent with the shape and structure of used AAO templates.

     

Neumann problems resonant at zero and infinity

We consider a semilinear Neumann problem with a reaction which is resonant at both zero and ±∞. Using a combination of methods from critical point theory, together with truncation techniques, the use of upper–lower solutions and of the Morse theory (critical groups), we show that the problem has at least five nontrivial smooth solutions, four of which have constant sign (two positive and two negative).     

IR spectra of CH3F in liquid and solid noble gas solutions

The IR absorption spectra of CH3F doped Ar, Kr and Xe solutions have been recorded near the melting point. The full widths at half maximum of fundamental bands increase noticeably after crystallization of the Xe and Kr solutions. A slight narrowing of the bands is observed just below the freezing point of the Ar solution. Treated in the framework of the Debye model for the J-diffusion of a symmetric top rotation, the results suggest a weaker perturbation of rotational motion of CH3F in the ordered Xe and Kr solids at least near the freezing point. At the same time, molecular rotation becomes more hindered when going to solid Ar. The broadening effect has been found to correlate with a hopping increase of the vibrational energy relaxation time, measured by the IR-IR double resonance method.     

Existence and multiplicity of solutions for second order periodic systems with the <Emphasis Type="Italic">p</Emphasis>-Laplacian and a nonsmooth potential

In this paper we study nonlinear periodic systems driven by the ordinary p-Laplacian with a nonsmooth potential. We prove an existence theorem using a nonsmooth variant of the reduction method. We also prove two multiplicity results. The first is for scalar problems and uses the nonsmooth second deformation lemma. The second is for systems and it is based on the nonsmooth local linking theorem.     

Microelectrode array fabricated in low temperature cofired ceramic (LTCC) technology

This work presents the development of a novel construction of an integrated microelectrode array. The device was fabricated on a ceramic support, with the use of low temperature cofired ceramics technology. Model potassium-selective membranes were applied on the surface of PdAg/AgCl electrodes formed on the ceramic substrate. The obtained microsensors exhibited very good repeatability, reproducibility, and sensitivity. The array of microelectrodes covered with polymeric layers of various selectivities was applied as an electronic tongue to differentiate between various diet supplements.     

A Bistable Molecular Switch Driven by Photoinduced Hydrogen‐Atom Transfer

The occurrence of photoinduced hydrogen atom transfer between two remote spots of a molecule is experimentally demonstrated. This photoprocess involves the intermediacy of an intramolecular “crane”. In an experimental case study, 7‐hydroxy‐4‐methylquinoline‐8‐carbaldehyde monomers isolated in low‐temperature Ar matrices are investigated. On UV (λ>295 nm) irradiation, a hydrogen atom is transferred from the O⁷H group to the N¹ atom of the quinoline ring. Subsequent irradiation with UV (λ>360 nm) light reveals that the phototransformation is partially photoreversible. In the studied hydrogen‐atom‐transfer process, the exocyclic carbaldehyde group plays the role of an intramolecular crane. The possible application of systems analogous to 7‐hydroxy‐4‐methylquinoline‐8‐carbaldehyde as optically driven molecular switches is discussed.     

On the Interplay of Regularity and Decay in Case of Radial Functions II. Homogeneous Spaces

We deal with decay and boundedness properties of elements of radial subspaces of homogeneous Besov and Triebel-Lizorkin spaces. For the region of parameters which are of interest for us these homogeneous spaces are larger than the inhomogeneous counterparts. By switching from the inhomogeneous spaces to the homogeneous classes the properties of the radial elements change. Our investigations are based on the atomic decompositions for radial subspaces in the sense of Epperson and Frazier (J.?Fourier Anal Appl. 1:311?C353, 1995). Finally, we apply these results for deriving some assertions on compact embeddings on unbounded domains.     

GSH Protects the Escherichia coli Cells from High Concentrations of Thymoquinone

The aim of the present study was to evaluate the potential protective effect of glutathione (GSH) on Escherichia coli cells grown in a high concentration of thymoquinone (TQ). This quinone, as the main active compound of Nigella sativa seed oil, exhibits a wide range of biological activities. At low concentrations, it acts as an antioxidant, and at high concentrations, an antimicrobial agent. Therefore, any interactions between thymoquinone and glutathione are crucial for cellular defense against oxidative stress. In this study, we found that GSH can conjugate with thymoquinone and its derivatives in vitro, and only fivefold excess of GSH was sufficient to completely deplete TQ and its derivatives. We also carried out studies on cultures of GSH-deficient Escherichia coli strains grown on a minimal medium in the presence of different concentrations of TQ. The strains harboring mutations in gene ΔgshA and ΔgshB were about two- and fourfold more sensitive (256 and 128 µg/mL, respectively) than the wild type. It was also revealed that TQ concentration has an influence on reactive oxygen species (ROS) production in E. coli strains—at the same thymoquinone concentration, the level of ROS was higher in GSH-deficient E. coli strains than in wild type.     

Crystal nucleation in an electric field

Nucleation of polar and apolar crystals in an electrostatic field has been analyzed. The analysis is based on the extended nucleation theory which takes into account orientation of amorphous kinetic elements and the resulting crystals. In an electric field free energy of transformation is orientation-dependent which leads to orientation and field effects in thermodynamic (critical crystallization temperature) and kinetic crystallization characteristics (thermal and athermal nucleation rates).