In this note we sharpen the lower bound previously obtained by Lobanov et al [LLP10] for the spectrum of the 2D Schrödinger operator with a δ-interaction supported on a planar angle. Using the same method we obtain the lower bound on the spectrum of the 2D Schrödinger operator with a δ-interaction supported on crossing straight lines. The latter operators arise in the three-body quantum problem with δ-interactions between particles.

The problem of particle storage in nanolayered structures will be considered. Local perturbations of nanolayers can lead to the appearanceof eigenvalues of the corresponding one-particle Hamiltonian. To study particle storage it is necessary to deal with the multi-particle problem. This problem faces essential computational difficulties due to the great increase of the spatial dimension. Using a composite of natural physical models, analytical methods and computational approaches allows one to simplify the problem and to obtain useful results for application. Particularly, the Hartree method and Finite Elements Method (FEM) are used. The discrete spectrum of the Hamiltonian for two interacting particles is considered. Two different types of perturbation are considered: deformation of the layer boundary and a small window in a wall between two layers. The relation between the system parameters (interaction intensity- waveguide deformation) ensuring the existence of a non-empty discrete spectrum is studied. A comparison of particle storage efficiencies is made for these two cases.

Living systems and free water were studied with the help of near-field radio-frequency (NFRF) probing methods. The results of this analysis suggest that processes within biological systems are comparable with those in ordinary water. The presented data suggest that near-field radio-frequency probing can be a useful diagnostic tool for the analysis of the radio-frequency fields generated by biological objects.

We performed theoretical analysis of a sidebands-based quantum cryptography system with two types of detec tors: an avalanche photodiode and a superconducting photon counter. The influence of detector parameters on eavesdropper “Intercept-resend” attack efficiency was investigated.

In the present experimental study, the precipitation of basic yttrium nitrate from aqueous solutions allowed the optimization of conditions for the preparation of loosely aggregated Y₂(OH)₅NO₃·1.5H₂O, the thermal decomposition of which, under controlled annealing, permitted the synthesis of yttria nanoparticles with desirable microstructure. The latter material can be widely used to manufacture yttria optical ceramics. Y₂(OH)₅NO₃·1.5H₂O thermolysis occurs via the formation of a metastable hexagonal Y₂O₃-based phase (a = 8.04, c = 12.37 Å).

The spatial and temporal dependence of the electric field amplitude of a terahertz (THz) pulse of several oscillations in the far field near the focal plane of a parabolic mirror was experimentally obtained. During experimentation a space-time anomaly was discovered in the diffraction patterns. In the wave front of the field the amplitude decreases to zero, and going through this spatial plane, the phase of oscillations changes, while in the integrated intensity, there is a dip in the curve. The results can be applied in pulsed terahertz optics and spectroscopy.

Oxyfluoride nano-glass-ceramics doped with neodymium ions have been developed and synthesized. The precipitation of crystalline phase in neodymium nano-glass-ceramics after heat treatment has been experimentally investigated. The neodymium ions are incorporated into the nanosize crystalline phase of PbY(_1-x)Nd(_x)OF₃.

The effect of high energy electron beam irradiation on the optical properties of TiO₂ nanoparticles was studied in order to improve the optical absorption performance and photo-activity. Electron beam irradiation may have resulted in size reduction, which in turn caused an increase of the optical band gap and photoluminescence intensity. Irradiation at a suitable dose rate was found to enhance the optical absorption performance and photo-activity of the tested TiO₂ nanoparticles.

In this paper a stepwise compaction process of a ring semi-stiff polymer chain placed in a 3d conical nano-cavity and being under the action of the increasing external field is studied. Compaction from a circle like shape to several toroidal-like loops for a three-dimensional system was observed. The thermodynamic stability of these toroidal-like structures was investigated by observing a hysteresis of the compaction extension curves. This study extends our previous work [1] with investigation of the effect of the cone opening angle variation on the distinct shape transitions.

A system of Kohn-Sham equations was solved self-consistently for the two-dimensional, spatially separated electrons and holes. A series of magic numbers were found for the total angular momentum of the electrons and holes in a strong magnetic field. The change of the angular momentum of the charge carriers was shown to lead to oscillations of the persistent current.

Hexagonal shaped LaF₃ nanocrystals (NC) doped by Nd³⁺ and Sm³⁺ ions were synthesized using a domestic microwave oven. The powder XRD study confirmed that the crystalline size of the particle was approximately 20 nm (JCPDS standard card (32–0483) of pure hexagonal LaF₃ crystals). The Transmission Electron Microscope (TEM) analysis indicated the size of the primary and secondary particles were between 15–20 nm. The presence of fundamental groups was verified by FTIR spectra. The synthesized nanocrystals were also studied for Non-Linear Optical (NLO) properties. The Second Harmonic Generation (SHG) efficiencies of LaF₃: Nd³⁺, Sm³⁺containing rare earth elements were found to be less than that of pure Potassium Dihydroxyl Phosphate (KDP) crystals. Keywords: microwave radiation, hexagonal shape, luminescent properties, x-ray diffraction.

Different carbon sources (e.g. hydrocarbons, oxygen containing organic compounds) were evaluated for their use in the chemical vapor deposition (CVD) process of carbon nanotube (CNT) production with regards to their efficiency and environmental safety. The effects of both the carbon source and gas feed rates on the yield of the obtained CNT’s were determined. The data obtained indicate that intermediate species formed in gas-phase thermal transformations of carbon sources play important roles in the CVD process of CNTs growth. Particularly, it is supposed that ketene, which is an intermediate species in the thermal decomposition of acetone , is the immediate source of carbon for CNTs growth in the CVD processes utilizing acetone as a carbon source.

 The effect of the oxide-chemostimulator V₂O₅ and the inert component Al₂O₃ binary compositions on the thermal oxidation of InP have been studied. The area of negative deviation of nanoscale oxide film thickness on InP from the additive joint effect has been established with a minimum for a composition of 20% Al₂O₃ + 80% V₂O₅. A decrease in the transit efficiency effect of V₂O₅ chemostimulator in composition with Al₂O₃ has been associated with an intensification of the transformation of V₂O₅ into V₂O₃, which is not an oxygen transitor.

Fe³⁺ ion doped barium titanate (BT) nanopowders were synthesized by the sol gel route. The average size of tetragonal bariun titanate (t-BT) powders lies in the range 16–40 nm. The specimens show ultraviolet (UV) emission (peak at 376 nm) along with emission in violet, blue, green and yellow color. The blue band (peak at 452 nm) is seen to grow significantly with annealing temperature. This band arises due to Ti³⁺ defects which are stabilized by Fe³⁺ ions in BT specimens. The samples show two distinct Electron Paramagnetic Resonance (EPR) bands of g-value around 4.11 and 1.98, which originated from Fe³⁺ ions and Ti³⁺ defects respectively. A correlation between the photoluminescence (PL) and EPR band intensity, grown from same species, was found.

Cis-[Co^III(tn)₂(Rpy)Br]Br₂, (R =4-CN, H, 4-Bz, 4-Me, 4-Et, and 4-MeNH), in aqueous 2-propanol exhibit varying adsorption characteristics and led to surface compound formation. UV (λ = 254) excitation of the nano-TiO₂//cobalt(III)-(Rpy) surface compound resulted in interfacial electron transfer (IFET) reaction. The IFET has been found to be dependent upon the coordination environment of the complex, more precisely due to the Rpy ligand. In addition, the proposed mechanism of the IFET reaction includes the formation of a Co^II ion implanted in nanocrystalline TiO₂. This photoreduction was found to be solvent controlled. The photoefficiency of the Co^II_aq formation was spectrally analyzed simultaneously as Co^II:TiO₂ was isolated from the photolyte solution. The isolated solid was subjected to FTIR, DRS, PXRD, and SEM-EDX instrumental analysis. It is concluded that the removal of metal ion in the form of a complex is coordination structure dependent, hence, seems more specific in removal efficiency and in doping the anatase lattice.

The density and Coefficient of Viscosity for Polyvinyl chloride/poly(methyl methacrylate)(PVC/PMMA)blends in tetrahydrofuran at 303.15 K and 313.15 K were measured. These measured parameters were then used to estimate few other related physical quantities like Huggin’s constants and the interaction parameters μ and α proposed by Chee and Sun et al. to identify the molecular interaction arising in the mentioned polymer blend solutions. The peculiar deviation confirms the structural changes in the solution of blends.

The conductance of a molecular device is sensitive to the contact geometry between the molecules and the probing electrodes. Combining the density functional theory calculations (DFT) for molecular electronic structure with a non-equilibrium Green’s function (NEGF) method for electron transport, we calculate the molecular conductance of carbon dimer connected between Au leads through two different anchoring atoms  Se and Te. The current-voltage characteristics and transmission spectra of two systems are studied. The results exhibit that, depending on the anchoring groups and the subsequent different metal-molecule chemical bonds, the current varies over more than four times of magnitude under the same bias. Furthermore, the system exhibits negative differential resistance (NDR) effect, when anchored with Te atom. This emphasizes  the great importance of the anchoring groups in molecular devices.