This PDF file contains the front matter associated with SPIE Proceedings Volume 9448, including the Title Page, Copyright information, Table of Contents, Author Index, Introduction, and Conference Committee listing.

In this article, the implementation of low-coherence interferometer with signal processing in time domain for sugar content determination in aqueous solution is presented. The elaborated measurement set-up was tested with the use of synthesized source made of two low-coherence sources. The use of two sources with dedicated parameters enabled to obtain a proper metrological parameters of the measurement system. The elaborated low-coherence system enables to measure sugar content in aqueous solution with correlation coefficient R2 equal to 1, and the relative error of measurement in the range of ± 5,8%.

Fluorescent spectroscopy (FS) is becoming more widely used in chemistry, biology, in various fields of medical technology and medicine in general. Many purulent wounds, burns and other destructive inflammatory processes are accompanied by changes in the fluorescent activity of the tissues, which occurs due to a misbalance in accumulation of natural fluorophores: FAD, NADH, lipofuscin, porphyrins, structural proteins, etc. The study of redox ratio (RR), characterizing the metabolic processes, is important in the assessment of the metabolic activity ofmicrocirculatory-tissue systems (MTS). However, one of the big problems of the FS method is still the correct interpretation of the data and the development of practical methods for its application in clinical medicine. To solve this problem and create new diagnostic criteria, we propose to evaluate the adaptive capacity of MTS using indicators of links between nutritive blood flow and redox ratio during a physiological rest and functional load (occlusion test). As is known, these parameters (RR and nutritive blood flow) characterize the metabolic activity of tissues.We have performedan experimental study of the relationship between the RR, defined by FS, and nutritive blood flow, defined by the methods of laser Doppler flowmetry. Preliminary results in the study of a complex approach to diagnosis of the state of biological tissue were obtained. A positive relationship between the nutritive blood flow in the microcirculatory channel and RR of skin tissue is observed.The speed of change of metabolism in the phase of occlusion and reperfusion and duration of phase of recovery may be the criteria for adaptive capabilities of MTS, which has practical significance for physiology and medicine.

The study is aimed to determine the digital capillaroscopy possibilities in early diagnostics of an arterial hypertension. A total of 123 adult persons were examined in the study. The first group consisted of 40 patients with prehypertension (BP 130–139/85–89 mm Hg). The second group included 36 patients with 1-2 stage of hypertension (mean systolic BP 152.7±12 mm Hg). Patients in both groups did not receive regular drug therapy. The group of volunteers (n=47) included healthy adults without signs of cardiovascular pathology. The capillary circulation was examined on the nailbed using the optical digital capillaroscope developed by the company "AET", Russia. Diameters of the arterial and venous segments, perivascular zone size, capillary blood velocity, the degree of arterial loops narrowing and the density of the capillary network were estimated. In patients with arterial hypertension and even in patients with prehypertension remodeling and rarefaction of capillaries and the expressed narrowing their arterial loops were manifested. The results of the study revealed the presence of abnormalities of microcirculation parameters in patients of both groups. The capillaries density in both groups of patients was significantly lower than in healthy persons. The significant narrowing of arterial loops was revealed in patients with both arterial hypertension and prehypertension, in comparison with healthy volunteers. Capillary blood velocity did not differ significantly between healthy volunteers group and the group of prehypertensive patients. However in patients with hypertension this parameter was significantly lower in comparison with control group.

A new method of an optical inhomogeneity detection in strongly scattering media having optical properties of biological tissue Time-Resolved Diffuse Optical Tomography (TR-DOT) is described. The method is based on preliminary processing of a three-dimensional surfaces obtained from the set of time-resolved data in the Cartesian coordinate system, followed by their conformal transform into surfaces in the cylindrical coordinate system. The key feature of the method is application of Late-Arriving Photons (LAP) diffusely transmitted through turbid objects. (i) LAP of each TPSF (Time Point Spread Function) standardized for a minimum angle; (ii) the resulting normalized function approximated by straight lines; (iii) normalized function is modified with the additional factor, K; (iv) final transform to the cylindrical coordinates.

We demonstrate an optical parametric oscillator (OPO) based on two HgGa₂S₄ (HGS) crystals with exceedingly wide tuning range from 4.2 μm to 10.73 μm. The HGS OPO was pumped by Q-switched Nd:YLF laser at 1.053 μm with a 5-7 ns pulse duration. Absorption spectrum of ammonia was presented to demonstrate the feasibility of the OPO system for spectroscopic measurements and gas detection.

The advantages of microstructured fibers application to photometrical determination of positive and negative agglutination reaction is discussed. One can use this method for blood typing and determination of Rh affinity. The method is based on discrimination of the scattering properties of blood probes with a specific and a non-specific agglutinating serum.

It is proposed an integrated approach to the study of basilar artery blood flow using 3D laser Doppler anemometer for identifying the causes of the formation and development of cerebral aneurysms. Feature of the work is the combined usage of both mathematical modeling and experimental methods. Described the experimental setup and the method of measurement of basilar artery blood flow, carried out in an interdisciplinary laboratory of Hospital Rechts der Isar of Technical University of Munich. The experimental setup used to simulate the blood flow in the basilar artery and to measure blood flow characteristics using 3D laser Doppler anemometer (3D LDA). Described a method of numerical studies carried out in Tambov State Technical University and the Bakoulev Center for Cardiovascular Surgery. Proposed an approach for sharing experimental and numerical methods of research to identify the causes of the basilar artery aneurysms.

This paper reports preliminary studies on use of Raman spectroscopy for investigation of blood. High quality blood spectra were recorded in-vitro with excitation wavelengths of 830 nm. Because of complex composition of the blood as well as by light attenuation and scattering in the tissues, spectra set up from wide, low-intensive Raman bands and intensive optical background. To get information about origin of bands in Raman spectra it is necessary to create phantom, which would show influence of this parameter and can be used to calibrate the Raman measurement system. Spectra of phantoms of selected blood components were acquired and discussed.

As a phantom of native blood capillary the plastic capillary tube and as a model of red blood cells the yeast cells are considered. Plastic capillary has circular a cross-section with diameter ranging between 20 and 40 μ. For velocity estimation of polystyrene beads which had a role of tracers in water the particle image velocimetry method is realized using NI Labview Vision standard functions of image processing. It is shown that in spite of the presence of uncompensated spherical aberration emerging from refraction incident beam in curved plastic capillary walls yeast cells can be confined in stable 3D trap.

The study of blood microcirculation is one of the most important problems of the medicine. This paper presents results of experimental study of cerebral blood flow microcirculation in mice with alloxan-induced diabetes using Temporal Laser Speckle Imaging (TLSI). Additionally, a direct effect of glucose water solution (concentration 20% and 45%) on blood flow microcirculation was studied. In the research, 20 white laboratory mice weighing 20-30 g were used. The TLSI method allows one to investigate time dependent scattering from the objects with complex dynamics, since it possesses greater temporal resolution. Results show that in brain of animal diabetic group diameter of sagittal vein is increased and the speed of blood flow reduced relative to the control group. Topical application of 20%- or 45%-glucose solutions also causes increase of diameter of blood vessels and slows down blood circulation. The results obtained show that diabetes development causes changes in the cerebral microcirculatory system and TLSI techniques can be effectively used to quantify these alterations.

Durability of bonded interfaces between dentin and a polymer material in resin-based composite restorations remains a clinical dentistry challenge. In the present study the evolution of bonded interfaces in biological active environment is estimated in vivo. A novel in vivo method of visual diagnostics that involves digital processing of color images of composite restorations and allows the evaluation of adhesive interface quality over time, has been developed and tested on a group of volunteers. However, the application of the method is limited to the analysis of superficial adhesive interfaces. Low-coherent optical computer tomography (OCT) has been tested as a powerful non-invasive tool for in vivo, in situ clinical diagnostics of adhesive interfaces over time. In the long-term perspective adhesive interface monitoring using standard methods of clinical diagnostics along with colour image analysis and OCT could make it possible to objectivise and prognosticate the clinical longevity of composite resin-based restorations with adhesive interfaces.

A new method of hard tooth tissues laser treatment is described. The method consists in formation of regular microdefects on tissue surface by mid−infrared erbium laser radiation with propagation ratio M²<2 (Er-laser microprocessing). Proposed method was used for preparation of hard tooth tissues surface before filling for improvement of bond strength between tissues surface and restorative materials, microleakage reduction between tissues surface and restorative materials, and for caries prevention as a result of increasing microhardness and acid resistance of tooth enamel.

Optical clearing of the rat skin under the action of propylene glycol was studied ex vivo. It was found that collimated transmittance of skin samples increased, whereas weight and thickness of the samples decreased during propylene glycol penetration in skin tissue. A mechanism of the optical clearing under the action of propylene glycol is discussed. Diffusion coefficient of propylene glycol in skin tissue ex vivo has been estimated as (1.35±0.95)×10^-7 cm²/s with the taking into account of kinetics of both weight and thickness of skin samples. The presented results can be useful for enhancement of many methods of laser therapy and optical diagnostics of skin diseases and localization of subcutaneous neoplasms.

For correct identification of fluorophores in fluorescence lifetime imaging in vivo it is important to account for widening of fluorescent kinetics curve due to light scattering and absorption in turbid medium. This widening leads to the difference between real and measured lifetimes of a fluorescent agent. We studied this effect for media with different optical properties and lifetimes corresponding to those of real fluorophores applying Monte-Carlo simulation. We found that for the fluorophore depths up to 15 mm for reduced scattering coefficient varying from 0.15 to 4.8 mm^-1 and absorption coefficient varying from 0.0025 to 0.08 mm^-1 this difference is insignificant for long-lived fluorophores (typical fluorescent proteins), however, it should be taken into account for fluorophores with lifetimes of several hundred picoseconds. Results of numerical simulation are confirmed by the results of the model experiment.

The research results of monitoring of viable cells in a cellular-tissue graft using confocal laser fluorescence microscopy at 488 nm and 561 nm with the use of fluorophore propidium iodide (propidium iodide, PI Sigma Aldrich USA) are presented. The processing of the received images was carried out using the software ANDOR. It is experimentally shown that the method of confocal fluorescence microscopy is one of the informational methods for detecting cells populated in a 3-D bio-carrier with a resolution of at least 400 nm. Analysis of the received micrographs suggests that the cells that were in a bio-carrier for 30 days in a synchronous ground-based experiment retained their viability compared to a similar space-based experiment in which the cells were hardly detected in a bio-carrier.

Spectral Fourier analysis of experimentally acquired velocity time dependencies, V(t), of shuttle endoplasmic motility in an isolated strand of plasmodium of slime mold Physarum Polycephalum has been realized. V(t) registration was performed in normal conditions and after the treatment by respiration inhibitors, which lead to a complete cessation of endoplasmic motion in the strand. Spectral analysis of the velocity time dependences of the endoplasm allows obtaining two distinct harmonic components in the spectra. Their ratio appeared to be constant in all cases, ν2/ν1=1.97±0.17. After the inhibitors are washed out respiratory system becomes normal, gradually restoring the activity of both harmonic oscillatory sources with time. Simulated velocity time dependences correspond to experimental data with good accuracy.

As a result of a recent years study on the Karelia shore of the White Sea more than ten relict lakes in different stages of separation from the sea have been discovered. Five of them are located close to the Nikolai Pertsov White Sea Biological Station of Moscow State University. Such separated lakes are interesting to explore for their firm vertical stratification. Water layers differ not only by temperature, salinity and other physic and chemical characteristics and optical properties, but also by ibhabiting microorganisms and by the quality of dissolved organic matter. To study phototropic organisms in water sampled from different depths we used spectroscopic techniques. Identification of the main bands in the absorption and fluorescence spectra showed that there are two main groups of photosynthetic organisms in the redox zone (chemocline): unicellular algae containing chlorophyll a and green sulfur bacteria with bacteriochlorophylls c, d, e. Spectral data were compared with physical and chemical characteristics of the water layer (temperature, salinity, pH, dissolved oxygen and sunlight illumination at certain depth). It gave an opportunity to compare vertical profiles of oxygen and hydrogen sulphide concentration with the number and distribution of oxygenic and anoxygenic phototrophic microorganisms. Maximum abundance of both algae and green sulfur bacteria were achieved within the redox zone. Typical thickness of the layer with the highest concentration of microorganisms did not exceed 10-20 cm.

In this paper results of application of laser Raman spectroscopy for increasing reliability of molecular DNA computations are presented. It is shown that elaborated method provides the accuracy of determination of concentration of individual nitrogenous bases 0.03 g/l and the accuracy of determination of total DNA concentration in the solutions 0.04 g/l by Raman spectra.

One of the complicating factors for environmental situation is degassing of land. The high concentrations of hydrogen near the bearing metal structures can weaken them as a result of embrittlement. Therefore, the study problems of hydrogen concentration in the soil and hydrogen influence on living organisms are relevant. However, the exit of deep hydrogen has a volley character. This problem can be solved by the plant bioobjects as the local integral indicators. The dandelion (Taráxacum) was selected as the research object. The collection of objects was produced from the degassing zone and a zone without degassing. Selection of degassing zone was driven by information that was provided by the Volga branch of the Institute of Geology and Exploration of fossil fuels of the Samara Region. Experimental studies of the hydrogen influence on the optical properties of plants were conducted using a complex of Raman spectroscopy and confocal microscopy. Laboratory and field research were conducted. Raman spectroscopy was implemented using the experimental stand that includes a radiation source, a fiber system for collect and feed of radiation and SR-303i spectrophotometer with integrated digital camera ANDOR DV-420A-OE (1024 * 256). The experimental stand allows to work in the spectral range of 180 - 1200 nm and with a registration accuracy about 0.2 nm. A detailed analysis of the structural changes in plant cells under the hydrogen influence was performed by confocal microscopy.

The pro-apoptotic transcription factor p53 is involved in cell responses to injurious impacts. Using its inhibitor pifithrin- α and activators tenovin-1, RITA and WR-1065, we studied its potential participation in inactivation and death of isolated crayfish mechanoreceptor neuron and satellite glial cells induced by photodynamic treatment, a strong inducer of oxidative stress. In dark, p53 activation by tenovin-1 or WR-1065 shortened activity of isolated neurons. Tenovin-1 and WR-1065 induced apoptosis of glial cells, whereas pifithrin-α was anti-apoptotic. Therefore, p53 mediated glial apoptosis and suppression of neuronal activity after axotomy. Tenovin-1 but not other p53 modulators induced necrosis of axotomized neurons and surrounding glia, possibly, through p53-independent pathway. Under photodynamic treatment, p53 activators tenovin-1 and RITA enhanced glial apoptosis indicating the pro-apoptotic activity of p53. Photoinduced necrosis of neurons and glia was suppressed by tenovin-1 and, paradoxically, by pifithrin-α. Modulation of photoinduced changes in the neuronal activity and necrosis of neurons and glia was possibly p53-independent. The different effects of p53 modulators on neuronal and glial responses to axotomy and photodynamic impact were apparently associated with different signaling pathways in neurons and glial cells.

Nitric oxide (NO) is an important second messenger, involved in the implementation of various cell functions. It regulates various physiological and pathological processes such as neurotransmission, cell responses to stress, and neurodegeneration. NO synthase is a family of enzymes that synthesize NO from L-arginine. The activity of different NOS isoforms depends both on endogenous and exogenous factors. In particular, it is modulated by oxidative stress, induced by photodynamic therapy (PDT). We have studied the possible role of NOS in the regulation of survival and death of neurons and surrounding glial cells under photo-oxidative stress induced by photodynamic treatment (PDT). The crayfish stretch receptor consisting of a single identified sensory neuron enveloped by glial cells is a simple but informative model object. It was photosensitized with alumophthalocyanine photosens (10 nM) and irradiated with a laser diode (670 nm, 0.4 W/cm2). Antinecrotic and proapoptotic effects of NO on the glial cells were found using inhibitory analysis. We have shown the role of inducible NO synthase in photoinduced apoptosis and involvement of neuronal NO synthase in photoinduced necrosis of glial cells in the isolated crayfish stretch receptor. The activation of NO synthase was evaluated using NADPH-diaphorase histochemistry, a marker of neurons expressing the enzyme. The activation of NO synthase in the isolated crayfish stretch receptor was evaluated as a function of time after PDT. Photodynamic treatment induced transient increase in NO synthase activity and then slowly inhibited this enzyme.

Photodynamic therapy (PDT) is used for selective destruction of cells, in particular, for treatment of brain tumors. However, photodynamic treatment damages not only tumor cells, but also healthy neurons and glial cells. To study the possible role of NF-κB in photodynamic injury of neurons and glial cells, we investigated the combined effect of photodynamic treatment and NF-κB modulators: activator betulinic acid, or inhibitors parthenolide and CAPE on an isolated crayfish stretch receptor consisting of a single neuron surrounded by glial cells. A laser diode (670 nm, 0.4 W/cm2) was used as a light source. The inhibition of NF-κB during PDT increased the duration of neuron firing and glial necrosis and decreased neuron necrosis and glial apoptosis. The activation of NF-κB during PDT increased neuron necrosis and glial apoptosis and decreased glial necrosis. The difference between the effects of NF-κB modulators on photosensitized neurons and glial cells indicates the difference in NF-κB-mediated signaling pathways in these cell types. Thus, NF-κB is involved in PDT-induced shortening of neuron firing, neuronal and glial necrosis, and apoptosis of glial cells.

Radachlorin is a chlorine-derivative photosensitizer used currently in photodynamic therapy (PDT). We studied photodynamic effect of Radachlorin on neurons and surrounding glial cells. The crayfish abdominal stretch receptor and abdominal nerve cord of were used as models. Radachlorin absorption spectrum contained maximums at 420 and 654 nm and fluorescence maximum at 664 nm. In the crayfish stretch receptor Radachlorin localized predominantly to the glial envelope and penetrated only slightly into the neuron. Radachlorin accumulated rapidly in the nerve cord tissue within 30 min. Its elimination in the dye-free solution occurred slower: 11% loss during 2h. Radachlorin-PDT inactivated the neuron, induced necrosis of neurons and glial cells and glial apoptosis at concentrations as low as 10^-10-10^-9 M. rapidly accumulates in the nervous tissue, mainly in glial cells. High photodynamic efficacy, the adsorption spectrum with the red maximum within the “transparency window," rapid accumulation and elimination characterize Radachlorin as a promising photosensitizer for photodynamic therapy.

On the model of photodynamic haemolysis, the membranoprotective properties of a plant origin antioxidant, Gratiola officinalis L. extract, have been studied based on its ability to inhibit photodamage of sensitized erythrocyte membranes. The effect of different concentrations of the antioxidant on the photodynamic hemolysis has been studied; and the influence of incubation time on the membranoprotective properties of Gratiola officinalis L. extract has also been revealed.

New method of photoinactivation of plague microbes (bacteria Yersinia pestis) has been suggested. Rate of growth of colonies of Y. pestis EV NIIEG at specific regimes of photo processing have been analyzed. Dependence of growth on exposure time and concentrations of photosensitizer (methylene blue) has been studied. Number of colony forming units of Y. pestis EV NIIEG bacteria as a function of intensity of light and concentration of methylene blue has been scrutinized.

The effect of conformation and electronic structure of fluorescent probes based on 1,8-naphthalimide and aniline derivatives (4-methoxyaniline and N,N-dimethyl-p-phenylenediamine) on the intramolecular photoinduced electron transfer (PET) was investigated by density functional theory calculations (B3LYP/6-31G (d, p)). We established restricted rotation around spacer bonds of the model compounds and their protonated and oxidized forms do not block the convergence of the nitrogen atoms involved in the electron transfer at a distance of ~3Å, which is adequately for PET. Computed values of protonation free energy for the gas-phase (ΔG²⁹⁸ _r) show that the investigated fluorescent probes are predominantly protonated on the nitrogen atoms of the donor moiety. Electron population and localization of the frontier orbitals (LUMO, HOMO, HOMO_-1) on the donor and acceptor moieties are transformed under protonation and one-electron oxidation of fluorescent probes. The results show that appearance or disappearance of the PET can be predicted by the energy difference between the frontier orbitals and the nature of their location of donor and acceptor moieties, which is in agreement with the PET theory and observed experimental data.

We have studied the processes of quenching of photoexcited states of fluorescent probes and quenching of the fluorescence of the chromophores of human serum albumin (HSA) by heavy metal ions (HM): cations Tl⁺, Pb²⁺, Cu²⁺, Cd²⁺, and the anion of iodine (I^-). We used the dye from xanthene series – eosin as a fluorescent probe. By quenching of the fluorescence of protein chromophores we found an influence of HM on the structure of proteins, resulting in a shift of the peak of the fluorescence of HSA tryptophanyl. This can be explained by proteins denaturation under the influence of heavy metals and penetration of water into the inner environment of HSA tryptophan. It was established that the constant of the quenching of the probe phosphorescence is much higher than the fluorescence, which is explained by significantly longer lifetime of the photoexcited states of fluorescent probes in the triplet state than in the singlet.

Photodynamic therapy is a prospective treatment modality of brain cancers. It is of importance to have information about relative survival rate of different cell types in nerve tissue during photodynamic treatment. Particularly, for development of sparing strategy of the photodynamic therapy of brain tumors, which pursuits both total elimination of malignant cells, which are usually of glial origin, and, at the same time, preservation of normal blood circulation as well as normal glial cells in the brain. The aim of this work was to carry out comparative survival study of glial cells and cells composing walls of blood vessels after photodynamic treatment, using simple model object – ventral nerve cord of crustacean.

In study the evaluation of the influence of gold nanorods on morphological indicators of red bone marrow and peripheral blood of rats with diabetes and transplanted liver tumor after intravenous administration of gold nanorods was conducted. We used gold nanorods with length 41 ± 8 nm and diameter of 10.2±2 nm, synthesized in the laboratory of nanobiotechnology IBPPM RAS (Saratov). After intravenous administration of gold nanorods the decrease of leukocytes, platelets and lymphocytes was observed in animals of control group in blood. It was marked the decrease of the number of mature cellular elements of the leukocyte germ in bone marrow - stab neutrophils and segmented leukocytes, and the increase of immature elements- metamyelocytes, indicating the activation of leukocyte germ after nanoparticle administration. The decrease of leukocyte amount was noted in blood and the increase of cellular elements of the leukocyte germ was revealed in bone marrow, indicating the activation of leukocyte germ in rats with alloxan diabetes and transplanted tumors. The changes of morphological indicators of blood and bone marrow testify about stimulation of myelocytic sprouts of hemopoiesis in bone marrow as a result of reduction of mature cells in peripheral blood after gold nanoparticle administration.

Internal temperature of biological tissues was measured in real-time mode under close-to-in-vivo conditions. Research technique is based on the comparison of the temperature inside the biological object and changes in the fluorescence spectra of temperature-sensitive fluorescent semiconductor ZnCdS nanoparticles introduced into muscle tissue. The temperature dependence of the ratio of maximum fluorescence intensities of the nanoparticles and the biological tissue was approximately linear.

In the past several decades the problem of longevity and durability of adhesive interfaces between hard tooth tissues and composite resin-based materials are of great interest among dental researchers and clinicians. These parameters are partially determined by adhesive system mechanical properties. In the present research project nanoindentation has been examined to test hardness of dental adhesive systems. A series of laboratory experiments was performed to study the effect of light curing time and oxygen inhibition phenomenon on light-cured adhesive material hardness. An adhesive system Adper^TM Single Bond (3M ESPE) was selected as a material for testing. The analysis of experimental data revealed that the maximum values of hardness were observed after the material had been light-cured for 20 seconds, as outlined in guidelines for polymerization time of the adhesive system. The experimental studies of oxygen inhibition influence on adhesive system hardness pointed out to the fact that the dispersive layer removal led to increase in adhesive system hardness. A long – time exposure of polymerized material of adhesive system at open air at room temperature resulted in no changes in its hardness, which was likely to be determined by the mutual effect of rival processes of air oxygen inhibition and directed light curing.

Freeze-drying as known as lyophilization has been considered as a possible technique to improve the long-term stability of colloidal luminescent quantum dots (QDs) for perspective biomedical application. The paper describes synthesis of biocompatible CdSe-based core/shell QDs and discusses their optical and physical properties before and after freezedrying. Importantly, the dried nanoparticles can be stored for a long time under usual conditions and then can easily be redisperse in water at a desired concentration without such hard manipulations as sonication or heating. In this work two PEG-amine derivatives were applied for QDs pegylation: monoamine Jeffamine M1000 and diamine JeffamineED-2003. The use of different Jeffamines allows us to obtain QDs with different length of PEG chains and different ζ-potential. The influence of polymer composition on optical properties of the nanocrystals and on their stability after freeze-drying was studied.

It is demonstrated that the nonlinear photo-integrated micro- and nano-periodic second-order susceptibility lattices with very small amplitudes which were preliminarily recorded using bi-chromatic powerful laser light in amorphous glass materials can be increased up to some orders of magnitude under the action of a simple coherent monochromatic radiation. The optical increase of the small lattices takes place independent of the polarization and direction of propagation of the optical amplifying radiation and is achieved at various wavelengths. The observed phenomenon is not be explained only by nonlinear wave interaction in medium and also may be related to the microscopic asymmetry processes of the optical transitions between local centers in an isotropic medium that leads to the appearance and growth of the all-optically induced small micro- and nano-periodic electrical charges separations inside the sample. Possible mechanisms that may be responsible for the observed effects in the studied phosphate glasses are discussed.

Perspectives of photo-modification of different glass materials for creating of the optical frequency micro- and nanoconverters are considered. The experimental results of the nonlinear conversions of the visible laser radiation on the photo-integrated volumetric lattices of the second-order susceptibility, which were fabricated in isotropic glass materials by the action of the pulsed powerful bi-chromatic inter-coherent radiation of YAG:Nd laser, are presented. The experimental investigations of the frequency conversion of the light laser radiation have been performed in potentially perspective materials with variations of the chemical compounds of the fundamental matrix and also by the small changes of the additional doped concentrates. The separate attention was given to considering the samples with content of the rare-earth elements and the detailed analysis of the influence of the chemical compound was carried out.

Theoretical consideration of the nonlinear conversion of light in photo-integrated micro- and nano-periodic susceptibility lattices which could be created in different isotropic materials is presented. The phenomena of the frequency doubling of light and the parametrical amplification of light in transformed isotropic medium are investigated according into account the realistic picture of the possible formation of the space structures of second order susceptibility with micro- and nanoperiodicities by action of the intersecting Gaussian beams of the fundamental and doubled harmonics of the mutualcoherent powerful laser radiation. The developed theory is based on a model of the formation of long-lived electrostatic field in isotropic material by means of the coherent photo-galvanic effect and gives the interesting peculiarities of processes of the frequency doubling and parametrical amplification of light which are connected with the formation of the long-lived susceptibility structures in volumetric media. In contrast to the well known nonlinear crystals, it has been demonstrated that in photo-integrated space-periodic susceptibility there is a possibility to obtain a new regime of twobeam frequency conversion of light. Fundamental properties of the phenomena have been studied and the possible mechanisms of processes are discussed.

The dispersion characteristics characteristic of the hyperbolic metamaterial consists of graphene and semiconductor layers titled according to outer boundary are presented. The graphene – SiC structure seems promising due to realistic technology condition for its manufacturing. Possibility of control of the light propagating through such structure will be discussed.

Quantum dots are bright and stable fluorescence signal sources, but for most of applications they need an additional hydrophilization step. Unfortunately, most of existing approaches lead to QD’s fluorescence quenching, so there is a need for additional enhancing of hydrophilized QD’s brightness like UV irradiation, which can be used both on water insoluble QD’s with oleic acid ligands (in toluene) and on hydrophilized QD’s covered with UV-stable polymer (in aqueous solution). For synthesis of bright water-soluble fluorescent labels CdSe/CdS/ZnS colloidal quantum dots were covered with PAMAM dendrimer and irradiated with UV lamp in quartz cuvettes for 3 hours at the room temperature and then compared with control sample.

The development of new complexes of rare earth elements (REE) with chelating organic ligands opens up the possibility of purposeful alteration in the composition and structure of the complexes, and therefore tuning their optical properties. New ligands possessing two pyridine rings in their structure were synthesized to improve coordination properties and photophysical characteristics of REE compounds. Complexes of trivalent europium with novel chelating ligands were investigated using luminescence and absorption spectroscopy, as well as atomic force microscopy. Luminescence properties of new compounds were studied both for solutions and films deposited on the solid support. All complexes exhibit the characteristic red luminescence of Eu (III) ion with the absolute lumenescence quantum yield in polar acetonitrile solution varying from 0.21 to 1.45 % and emission lifetime ranged from 0.1 to 1 ms. Excitation spectra of Eu coordination complexes correspond with absorption bands of chelating ligand. The energy levels of the triplet state of the new ligands were determined from the phosphorescence at 77 K of the corresponding Gd (III) complexes. The morphology of films of europium complexes with different substituents in the organic ligands was investigated by atomic force microscopy (AFM). It strongly depends both on the type of substituent in the organic ligand, and the rotation speed of the spin-coater. New europium complexes with chelating ligands containing additional pyridine fragments represent outstanding candidates for phosphors with improved luminescence properties.

The surface morphology and optical activity of films based on chitosan in different chemical forms were investigated by methods of scanning electron and atomic force microscopy, spectropolarimetry. These film samples are used as substrates for optical waveguides, sorption material and as substrates for cell culturing tissue-engineering and scaffold constructions. The essential differences in the structural and morphological relief of thin films from chitosan of different chemical forms are established. It was found that the spectra of optical rotatory dispersion and circular dichroism of films of chitosan in the form of polysalts and polybases are significantly different in absolute values of the optical rotation of the plane and circularly polarized light.

The parameters of hydrogen bridges and oscillation spectra of complementary pairs of adenine-uracil formed by Watson- Crick and Hugstin and two reverse to them structures are calculated. Performed analysis shows that due to the characteristic oscillations of the IR spectra in the area of 1600-1800 and 2900-3500 cm^-1 it is possible to identify uniquely each of the four pairs in the gas phase and aqueous solution.

We present a novel technique for 3D-tracking micro- and nanoparticles with original lens-free dark-field holographic microscope. Combining lens-free and dark-field microscopy principles this technique allows for high accuracy localization of micro- and nanoparticles using single hologram acquired with compact setup built with minimal use of optical components. In this paper, we present technique of particles localization, experimental setup, technique of digital correction of spherical aberration, results of simulation and experimental data.

Fourier optics approach is employed in the work do describe formal theory of diffraction phase microscope (DPM). Final expression for optical field in registration plain is given. Optimal spatial filter diameter and numerical aperture is calculated theoretically. DPM is used in the work for reconstruction of phase map of red blood cells in blood slide. The filter windows diameter influence on phase map reconstruction is shown experimentally.

Particularities of interference signal shaping in white-light interferometer with uncompensated dispersive layer are discussed. We especially attended to dependence of interference pulse position on the dispersive layer properties. Phase refractive index of the layer tends to be substantially nonlinear function of wavelength within the wide emission band of ultra-low coherence thermal light source. In this case, it is the group refractive index dispersion that is beginning to exert an influence on interference signal formation. It is shown experimentally that influence consists in nonlinear dependence of interference pulse position on geometrical thickness of the dispersive layer. The results show that mismatch of the dispersive layer and compensator refractive indices in the third place can produce interference signal shift on the order of pulse width.

Suitability of zinc oxide (ZnO) layers grown using Atomic Layer Deposition for operation in optical-fiber extrinsic Fabry-Perot sensors is investigated using a numerical model. Reflectance spectra obtained using the developed model indicate that the application of these layers in optical-fiber extrinsic Fabry-Perot sensors is difficult as it may require a source whose spectrum width is about 300 nm. A series of ZnO layers grown on end faces of SMF-28 fiber were prepared and their reflectance spectra were recorded by an optical spectrum analyser in order to verify the modelling results. The spectra contain a series of peaks not predicted by the model, which is attributed to two-mode propagation in the SMF-28 fiber connecting the ZnO layer with the rest of the measurement system.

A digital optical system focused on work with laboratory animals for intravital capillaroscopy has been developed. It implements the particle image velocimetry (PIV) based approach for measurements of red blood cells velocity in laboratory rat stomach capillaries. We propose a method of involuntary displacement compensation of the capillary network images. Image stabilization algorithm is based on correlation of feature tracking. The efficiency of designed image stabilization algorithm was experimentally demonstrated. The results of capillary blood flow analysis are demonstrated.

A technique for spectral filtration of interference images in full-field optical coherence tomography is proposed, implemented and tested. It is based on the spectral selection of light in the registration channel of the interferometer by imaging acousto-optic tunable filter. It is demonstrated that the diffraction of two interfering optical beams via the same ultrasound wave does not destruct the coherence. This new technique, which can be named tunable-imaging-filter-based full-field spectral-domain optical coherence tomography (TIF FF SD OCT), is applicable for 3D surface and inner structure visualization of optically inhomogeneous biomedical objects with moderate spectral, lateral and axial resolution, however with rather high speed.

The acousto-optic-tunable-filter-based (AOTF-based) spectral imaging systems for non-invasive photoluminescence diagnostics are discussed. The problem of image distortion caused by AO interaction which causes the inaccuracy of spectral measurements is considered. The existing methods of AOTF calibration do not provide the full information about the image structure and the individual aberrations. It is proposed to reconstruct the optical path difference (OPD) caused by AOTF. For this purpose the experimental setup based on Shack-Hartmann sensor was assembled. It is shown that it allows defining the magnitude of the main aberrations of double AOTF are meridional and sagittal coma and some high-order components. Spectral dependence of OPD and its components is rather weak and shows a small chromatic image distortion. The obtained data is in good correspondence with the results of the theoretical studies of the double AOTFs. Wave front measurement may be effectively used for the study and optimization of existing AOTF-based spectral imagers. The effectiveness of this technique is demonstrated on the measurement of the spectrums of real biomedical tissues obtained by the endoscopic AOTF-based imager.

Prospective composite bioceramic titania coatings were obtained on intraosseous implants fabricated from medical titanium alloy VT16 (Ti-2.5Al-5Mo-5V). Consistency changes of morphological characteristics, physico-mechanical properties and biocompatibility of experimental titanium implant coatings obtained by oxidation during induction heat treatment are defined. Technological recommendations for obtaining bioceramic coatings with extremely high strength on titanium items surface are given.

Production of biocompatible nano-ceramic coatings is one of the major goals in prospective materials technology, particularly, in biomedical items, e.g. intraosseous implants and joint endoprostheses. Ceramic coatings obtained by the existing methods do not have the required structural properties of biocompatibility, which causes quality reduction. It has been stated that thermal induction preheating of substrate ensures the required structural organization of hydroxyapatite coating, grain size and shape in particular.

Object of study: Improvement of life quality of patients with high stroke risk ia the main goal for development of system for patient-specific modeling of cardiovascular system. This work is dedicated at increase of safety outcomes for surgical treatment of brain blood supply alterations. The objects of study are common carotid artery, internal and external carotid arteries and bulb. Methods: We estimated mechanical properties of carotid arteries tissues and patching materials utilized at angioplasty. We studied angioarchitecture features of arteries. We developed and clinically adapted computer biomechanical models, which are characterized by geometrical, physical and mechanical similarity with carotid artery in norm and with pathology (atherosclerosis, pathological tortuosity, and their combination). Results: Collaboration of practicing cardiovascular surgeons and specialists in the area of Mathematics and Mechanics allowed to successfully conduct finite-element modeling of surgical treatment taking into account various features of operation techniques and patching materials for a specific patient. Numerical experiment allowed to reveal factors leading to brain blood supply decrease and atherosclerosis development. Modeling of carotid artery reconstruction surgery for a specific patient on the basis of the constructed biomechanical model demonstrated the possibility of its application in clinical practice at approximation of numerical experiment to the real conditions.

Blood-brain barrier, which is a barrage system between the brain and blood vessels, plays a key role in the "isolation" of the brain of unnecessary information, and reduce the "noise" in the interneuron communication. It is known that the barrier function of the BBB strictly depends on the initial state of the organism and changes significantly with age and, especially in developing the "vascular accidents". Disclosure mechanisms of regulation of the barrier function will develop new ways to deliver neurotrophic drugs to the brain in the newborn. The aim of this work is the construction of atomistic models of structural components of the blood-brain barrier to reveal the mechanisms of regulation of the barrier function.

In this paper, we discuss a relationship between stress-induced formation of hypertension and ulcer bleeding and the level of serum testosterone in female and male rats. We show that the secretion of testosterone is an important sign of severity of stress-induced damages of vascular homeostasis in males but not in females.

We study pathological changes in cerebral venous dynamics in newborn mice using the laser speckle contrast imaging and the detrended fluctuation analysis with a special attention to the latent stage of the development of the intracranial hemorrhage. We show that this stage is characterized by a high responsiveness of the sagittal sinus to pharmacological stimulations of adrenorelated dilation. We conclude that this effect can be considered as an important mechanism underlying the development of ICH in newborns.

We address the problem of conducted vasodilation, the phenomenon which is also known as functional hyperemia. Specifically, we test the mechanism of nondecremental propagation of electric signals along endothelial cell layer recently hypothesized by Figueroa et al. By means of functional modeling we focus on possible nonlinear mechanisms that can underlie such regenerative pulse transmission (RPT). Since endothelial cells (EC) are generally known as electrically inexcitable, the possible role of ECs in RPT mechanisms is not evident. By means of mathematical modeling we check the dynamical self-consistency of Figueroa's hypothesis, as well as estimate the possible contribution of specific ionic currents to the suggested RPT mechanism.

A method is presented to obtain information on tissue perfusability from capillary velocimetry experiments coupled with venous occlusion probe. The method based on data fitting to developed mathematical model describing the blood flow redistribution caused by the introduced occlusion. Using mathematical modeling, we identify the segment of velocity time courses that corresponds to tissue swelling process and thus allows ones quantify it. We also compared the results of direct measurement of red blood cells (RBCs) velocity with time courses obtained from finger-placed sensors of two types: (i) photoplethysmographic sensor used in pulsometry and (ii) piezoelectric sensor for sphygmography. The obtained results suggest the measurable contribution of RBCs aggregation process in optical pulse signal formation.

The elimination of low-frequency noise of breath and motion artifacts is one of the most difficult challenges of preprocessing rheographic signal. The data filtering is the conventional way to separate useful signal from noise and interferences. Conventionally, linear filtering is used to easy design and implementation. However, in some cases such techniques are difficult, if possible, to apply, since the data frequency range is overlapped with one of interferences. Specifically, it happens in aortic rheography, where some breathing process and pulmonary blood flow contributions are unavoidable. We suggest an alternative approach for breathing interference reduction, based on adaptive reconstruction of baseline deviation. Specifically, the computational scheme based on multiple calculation of Akima splines is suggested, implemented using C# language and validated using surrogate data. The applications of proposed technique to the real data processing deliver the better quality of aortic valve opening detection.

We propose a modification of OCT scanning pattern and corresponding signal processing for 3D visualizing blood microcirculation from complex-signal B-scans. We describe the scanning pattern modifications that increase the methods’ robustness to bulk tissue motion artifacts, with speed up to several cm/s. Based on these modifications, OCT-based angiography becomes more realistic under practical measurement conditions. For these scan patterns, we apply novel signal processing to separate the blood vessels with different decorrelation times, by varying of effective temporal diversity of processed signals.

We developed a Laser Doppler anemometer which uses a novel technique of signal processing to minimize the effect of undesirable light scattering. The technique has been applied to estimate Doppler frequency shift at flow velocity measurements. We have shown that technique is applicable for measurements in turbid media like biological tissues.

We address the problem of characterization of chaotic dynamics at the input of a threshold device described by an integrate-and-fire (IF) or a threshold crossing (TC) model from the output sequences of interspike intervals (ISIs). We consider the conditions under which quite short sequences of spiking events provide correct identification of the dynamical regime characterized by the single positive Lyapunov exponent (LE). We discuss features of detecting the second LE for both types of the considered models of events generation.

Sleep spindles are known to appear spontaneously in the thalamocortical neuronal network of the brain during slow-wave sleep; pathological processes in the thalamocortical network may be the reason of the absence epilepsy. The aim of the present work is to study developed changes in the time-frequency structure of sleep spindles during the progressive development of the absence epilepsy in WAG/Rij rats. EEG recordings were made at age 7 and 9 months. Automatic recognition and subsequent analysis of sleep spindles on the EEG were performed using the continuous wavelet transform. The duration of epileptic discharges and the total duration of epileptic activity were found to increase with age, while the duration of sleep spindles, conversely, decreased. In terms of the mean frequency, sleep spindles could be divided into three classes: ‘slow’ (mean frequency 9.3Hz), ‘medium’ (11.4Hz), and ‘fast’ (13.5Hz). Slow and medium (transitional) spindles in five-month-old animals showed increased frequency from the beginning to the end of the spindle. The more intense the epilepsy is, the shorter are the durations of spindles of all types. The mean frequencies of ‘medium’ and ‘fast’ spindles were higher in rats with more intense signs of epilepsy. Overall, high epileptic activity in WAG/Rij rats was linked with significant changes in spindles of the transitional type, with less marked changes in the two traditionally identified types of spindle, slow and fast.

In this paper we perform a time-frequency analysis of epileptic EEG patterns based on two approaches for characterizing nonstationary multi-frequency signals, namely, the continuous wavelet transform (CWT) and the empirical mode decomposition (EMD). Possibilities and limitations of both these techniques are considered, and a combined approach for automatic pattern detection is proposed.

This work proposes a new method for automatic marking epileptic spike-wave discharges in local field potential (LFP) signals. The method is based on empirical modelling using radial basis functions to approximate dependency of a further state on the current one. Number and type of radial basis functions used are adjusted to data based on statistical criteria. Due to this the method needs only a few manual efforts for its application to new data. The time resolution of the method is close to the sampling interval of the original data, and real time detection is possible. Detection accuracy of the proposed approach is validated analysing the LFP signals obtained using WAG/Rij rats.

This paper is devoted to the analysis of topological changes in complex networks that are reflected in the macroscopic characteristics. We consider a model of the complex network with the adaptive links, in which the synchronous dynamics leads to the appearance of clusters of strongly coupled elements and show that structural changes significantly affect the macroscopic dynamics. As the result, we demonstrate a high possibility of cluster formation in the network that can be analyzed via the consideration of macroscopic characteristics. We also discuss a prospective application for the detection of structural features of neural networks.

The one of most important problem in modern genetics, biology and medicine is determination of the primary nucleotide sequence of the DNA of living organisms (DNA sequencing). This paper describes the label-free DNA sequencing approach, based on the observation of a discrete dynamics of DNA sequence elongation phase. The proposed DNA sequencing principle are studied by numerical simulation. The numerical model for proposed label-free DNA sequencing approach is based on a cellular automaton, which can simulate the elongation stage (growth of DNA strands) and dynamics of nucleotides incorporation to rising DNA strand. The estimates for number of copied DNA sequences for required probability of nucleotide incorporation event detection and correct DNA sequence determination was obtained. The proposed approach can be applied at all known DNA sequencing devices with "sequencing by synthesis" principle of operation.

In the report the approach to protection of transmitted data by creation of pair symmetric keys for the sensor and the receiver is offered. Since biosignals are unique for each person, their corresponding processing allows to receive necessary information for creation of cryptographic keys. Processing is based on reconstruction of the mathematical model generating time series that are diagnostically equivalent to initial biosignals. Information about the model is transmitted to the receiver, where the restoration of physiological time series is performed using the reconstructed model. Thus, information about structure and parameters of biosystem model received in the reconstruction process can be used not only for its diagnostics, but also for protection of transmitted data in telemedicine complexes.

The problem of spatiotemporal pattern formation in the wall of arterial vesselsmay be reduced to 1D or 2D models of nonlinear active medium. We address this problem using the discrete array of non-oscillating (bistable) active units. We show how the specific choice of initial conditions in a 1D model with periodic boundary conditions triggers the self-sustained behaviour. We reveal the core of observed effects being the dynamical formation of localized (few-element size) autonomous pacemakers.

Basing on Dirac equation for interacting massless fermions, we propose a nonlinear model that describes a possible mechanism of ferromagnetism in graphene structures, resulting from electron-electron interaction and spontaneous breaking of spin symmetry of valence electrons. Qualitative predictions of the model are important for practical applications in spintronics. Localized kink-antikink patterns of valence electron spin density on the graphene surface are calculated, their interaction is described, and, finally, the formation of their quasi-bound metastable states (breathers) is investigated. The spectrum of breathers is calculated in both the analytical and the numerical form. Once created, the inverted population of the appropriate states may be used to generate quantum coherent nonlinear spin waves that can find practical applications in nanoelectronics and spintronics. Optical excitation and possible lasing transitions between the breather discrete states are discussed.

The article considers a mechanism for temperature distribution within metal surfaces subjected to laser irradiation as well as zones not affected by laser light. It is shown that the growth of the laser heating zone facilitates more even temperature distribution. Under an alternate laser pulse at a shorter distance, the temperature of the surface increases; it is added up to the residual temperature of the previous laser pulse, and then slowly decreases. All this stabilizes the residual voltage within metals.

The article considers a mechanism for combining surface temperatures of the closest laser pulse under a discrete laser treatment. It is shown that a minimal transfer of the working surface causes a uniform surface heating within the laser irradiation zone, in addition to slow cooling of the surface outside the laser heating area. This facilitates stabilization of the properties of the working surface and reduction of the residual voltage. A case of the rational mode for the laser treatment of slender parts, such as torque shafts, is also provided.

We study the problem of rotational excitation of molecules by an ultrashort laser pulse sequence. Recent experimental investigations [Phys. Rev. Lett. 109, 043003 (2012)] shows that there are quantum resonances in rotational dynamics of dinitrogens molecules for some values of pulse train period. We describe these results theoretically. Physical parameters of ultrashort laser pulse sequence for effective selective rotational excitation of dinitrogens isotopes were defined by numerical simulations.

The numerical model for calculating the dynamics of bidirectional ring fiber laser is presented. The model based on the transport equations for the complex amplitudes of electrical field of oppositely running waves and CIR method. The model includes equations for laser levels populations and its longitudinal harmonics due to saturation by oppositely running waves. The effect of SBS on the laser dynamics is investigated.

The numerical simulation results of the probe pulse duration influence on this pulse evolution in presence of electromagnetically induced transparency are presented. We investigate the cases of weak and strong input pulses in degenerated quantum transition Λ -scheme with inhomogeneous line broadening. The linear polarizations of probe and control radiation are supposed. According to our calculations, the weak input probe pulse regime is the most favorable for formation of more than one nanosecond duration probe pulse with small varying of envelop form by its transition. The strong input probe pulse condition is disadvantageous for preservation of pulse shape when the probe pulse travels across the medium, for duration less than several nanoseconds. This circumstance imposes restriction on operating speed of the perspective equipments, principle operation of which bases on the electromagnetically induce transparency effect.

Dispersion tailoring using photonic crystal cladding for slot waveguide is proposed. Numerical modeling based on the Maxwell equation for Te and TM modes of the photonic crystal is performed. Slot waveguide provide high intencity at the central area. Photonic crystal cladding of the slot waveguide allow us to compensate high values of the host glass dispersion.

Optical properties of open-ended single-wall carbon nanotubes (SW-CNT) are investigated by numerical simulation. The polarizability tensor, which describes changes in optical properties depending on the propagation direction of electromagnetic radiation, is analysed for different types of single-wall carbon nanotubes with various configurations. IR spectrums are investigated for nanotubes without impurities and nanotubes which contain carboxylic group – COOH.

This article describes the algorithm and the creation of programs for the input process automate the scaling factors of quantum mechanical force fields calculated in the natural coordinates using ab initio methods and the density functional theory (DFT-methods).

Squeezing for one- and two-mode two-atom Jaynes-Cummings model with intensity-dependent coupling has been investigated assuming the field to be initially in the coherent state. The time-dependent squeezing parameters have been calculated. The influence of the intensity of the cavity field and initial atomic state on the squeezing parameters has been analyzed.

In this paper we have investigated the atom-atom entanglement for degenerate two-photon Tavis-Cummings model with taking into account Stark shift and initial atomic coherence. Considering different initial coherent states we have derived that the atom-atom entanglement can be greatly increased or decreased due to the presence of the Stark shift. In addition, we have derived that the entanglement sudden death effect vanishes due to the presence of Stark shift for some initial states.

We have investigated the influence of dipole-dipole interaction and initial atomic coherence on dynamics of two-atom systems. We have considered a model, in which only one atom is trapped in a cavity, and the other one can be spatially moved freely outside the cavity. We have shown the possibility of disappearance of the entanglement sudden death effect in the presence of the dipole interaction of atoms. We have also derived that the initial atomic coherence can be used for effective control of the degree of the atom-atom entanglement.

We study a non-paraxial family of nondiffracting laser beams whose complex amplitude is proportional to an n-th order Lommel function of two variables. These beams are referred to as Lommel modes. We also study finite-energy paraxial Lommel-Gaussian beams with their complex amplitude being proportional to the Lommel function and to the amplitude of the Gaussian beam. Explicit analytical relations for orbital angular momentum of the Lommel modes and Lommel-Gaussian beams have been derived. Asymmetry of the Lommel modes depends on a complex parameter с. Besides, with the modulus of the с parameter increasing from 0 to 1, the orbital angular momentum of the Lommel modes increases from a finite value proportional to the topological charge n to infinity. The orbital angular momentum of the Lommel modes undergoes continuous variations, in contrast to its discrete changes in the Bessel modes. Simulation by the beam propagation method showed that in initial plane the transverse intensity distribution of the Lommel-Gaussian beam contains a light ellipse with two bright spots. During propagation, these spots rotate by an angle, close to 90 degrees, at a much smaller distance than the Rayleigh range.

We consider theoretically laser-assisted ionization of a helium atom by electron impact at large momentum transfer. Fully differential cross sections of these processes are studied as functions of the recoil-ion momentum for the cases when the residual He⁺ ion is left both in the bound (n = 1 and n = 2) and in the continuum states in the presence of a linearly-polarized laser field with frequency w = 1.55 eV and intensity I = 5×10¹¹W/cm². We inspect how the orientation of the polarization influences the laser-assisted momentum profiles using different models of the helium wave function. It is found that the Kroll-Watson sum rule is well applicable in the (e, 3 − 1e) case.

Highly non-linear chalcogenide glasses are considered as a prospective material for frequency comb generation in optical microresonators. Using of a 2D microresonator for tailoring the normal material dispersion of chalcogenide glass is analyzed by evaluation of the group velocity dispersion coefficient in near- and mid- infrared. This is done for both approximate and accurate modal resonances of the whispering gallery modes of a 2D circular chalcogenide resonators. The results show that the using of a chalcogenide resonator extends the spectral range of normal dispersion regime to longer wavelengths.

We consider superposition of two paraxial two-dimensional half Pearcey laser beams. By the beam propagation method (BPM), we study the beam intensity distribution in focal plane. For superposition with zero phase delay between the beams, the simulation showed that focal spot has a width of 0.36 free-space wavelengths, while superposition with phase delay of π allows obtaining two focal spots with a width of 0.42 free-space wavelengths.

It was numerically and experimentally shown that square-profile microsteps with width of 0.4 μm, 0.5 μm, 0.6 μm, 0.8 μm and height of 500 nm illuminated by linearly polarized laser light with wavelength λ = 633 nm formed near its’ surface photonic nanojets with intensity that is 6 times higher than the intensity of incident light. Experimentally measured diameters of photonic nanojets were equal to 0.44λ, 0.43λ, 0.39λ and 0.47λ (less than the diffraction limit 0.51λ).

In this paper we consider using the terahertz (THz) time domain spectroscopy (TDS) for non destructive testing and determining the chemical composition of the vanes and rotor-blade spars. A versatile terahertz spectrometer for reflection and transmission has been used for experiments. We consider the features of measured terahertz signal in temporal and spectral domains during propagation through and reflecting from various defects in investigated objects, such as voids and foliation. We discuss requirements are applicable to the setup and are necessary to produce an image of these defects, such as signal-to-noise ratio and a method for registration THz radiation. Obtained results indicated the prospects of the THz TDS method for the inspection of defects and determination of the particularities of chemical composition of aircraft parts.

Binary diffraction optical element was designed for polarization conversion from linear to radial. A grating period was equal to 400 nm, a relief height was equal to 110 nm. Simulation by FDTD method and Rayleight-Zommerfeld integral shown that there are radial polarized light beam in the far field with smooth angle dependence on the beam circle observation position. It was shown experimentally, that a gaussian laser beam with wavelength of 633 nm reflected from the polarization conversion plate contain a radially polarized light.

Nematic layers with a fine-domain random planar structure obtained using nonrubbed polymer alignment films exhibit a mixed, partly regular and partly diffuse transmission with complementary high-contrast channeled spectra of the regular and diffuse transmittances. We show experimentally that the power of the light scattered by such a layer can be controlled by an applied electric field. We demonstrate that under certain conditions, when a layer with random planar alignment is illuminated by a quasimonochromatic light beam, the power of the scattered component of the light transmitted by the layer has a nonmonotonic dependence on the voltage applied to the layer and that there are electrically-induced states in which the layer scatters all the transmitted light and states in which the layer scatters only a very small portion of the transmitted light. These features allow using electrically-driven cells with such layers as polarization-independent tunable diffusers.

A coherent dynamics of two-and three-level atoms in the ideal cavity were investigated. In particular, the investigation of the dynamics of three-level atoms (qutrits) interacting with photons in the cavity having two resonant frequencies close to the frequencies of the two allowed atomic transitions were performed. This model generalizes the well-known Tavis-Cummings model. Time dependencies of mean number of the cavity photons and level populations of atoms are computed and entanglement of atoms and photon fields states are discussed.

We study the dynamics of a neodymium-doped fiber laser coupled to ytterbium-doped fiber laser via nonlinear crystal which is placed inside the resonator. The transient signals may present different profiles depending on several conditions (degree of coupling between both lasers, pump powers of each one, resonator length, etc.) In particular, an appropriate choice of working conditions makes possible to suppress relaxation oscillations and to shorten the time elapsed since the moment of pump switch-on till steady state.

We study the evolution of quantum entanglement in the model of two identical qubits interacting with a singlemode laser field. The density matrix and Peres-Horodecki parameter are calculated within the frameworks of path-integral formalism. The quantum entanglement measure is shown to be strongly dependent upon the phase difference between the laser radiation acting on each cubit. This observation may offer the possibility of quantum entanglement stationary control by varying the distance between the qubits.