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The nature of anti-Stokes luminescence centers excited in the temperature range 77–300 K by light with wavelengths from 620 to 710 nm and intensities in the range 1015–1016 photons/cm2 in Zn0.75Cd0.25S microcrystals annealed in the presence of oxygen has been investigated. It is shown that the centers of two-photon excitation of this luminescence are clusters of native metal oxides (ZnO) n and (CdO) n, whose energy levels in the Zn0.75Cd0.25S band gap are 1.70–1.95 eV below the bottom of the conduction band. [ABSTRACT FROM AUTHOR]

The sensitized anti-Stokes luminescence excited by radiation with wavelengths from 610 to 750 nm and flux densities of 1014–1015 quanta/(cm2·s) is detected for microcrystals of Zn 0.6 Cd 0.4 S solid solutions with adsorbed organic malachite green and methylene blue dye molecules. The position of its excitation spectra coincides with that of the absorption spectra of adsorbed dye molecules, which suggests the cooperative mechanism of its occurrence. The possibility of amplification of the anti-Stokes luminescence by means of adsorption of silver atoms and few-atomic silver clusters, in addition to the dye molecules, on the Zn 0.6 Cd 0.4 S surface is investigated. It is assumed that in the latter case, the anti-Stokes luminescence is excited as a result of two-quantum optical transitions with electron or electron excitation energy transfer from the dye molecules adsorbed on the Zn 0.6 Cd 0.4 S surface to silver atoms and few-atomic silver clusters creating deep local states with photoionization energies of 1.8–2.0 eV in the gap. [ABSTRACT FROM AUTHOR]

For microcrystals of Zn0.6Cd0.4S with adsorbed molecules of a number of organic dyes, we have observed sensitized anti-Stokes luminescence excited by radiation with wavelengths in the range 610–750 nm and flux density 1014–1015 photons/cm2·sec. The positions of the bands in the excitation spectra for such luminescence match those of the absorption spectra for the adsorbed dye molecules, which is evidence in favor of a cooperative mechanism for its appearance. We have shown that enhancement of the anti-Stokes luminescence is possible when silver atoms and few-atom clusters appear on the Zn0.6Cd0.4S surface in addition to the dye molecules. We hypothesize that its excitation in the latter case occurs as a result of two-photon optical transitions. These transitions occur sequentially, with transfer of an electron or the electronic excitation energy from the dye molecules to silver atoms and few-atom clusters adsorbed on the surface of Zn0.6Cd0.4S, creating deep localized states in the bandgap with photoionization energies 1.80–2.00 eV. [ABSTRACT FROM AUTHOR]

We have studied the effect of the characteristic features of aggregation of some organic dye molecules during adsorption on the parameters of low-temperature sensitized anti-Stokes luminescence (SASL) in microcrystals of AgCl0.95I0.05 solid solutions. We have demonstrated the possibility in principle of varying the position of the maximum in the SASL excitation spectrum and its intensity by varying the concentration of the dye molecules deposited on the surface of the AgCl0.95I0.05 microcrystals. We have observed that the intensity of SASL excitation for these samples increases as different types of dye aggregates form on their surface. [ABSTRACT FROM AUTHOR]

An anti-Stokes luminescence band with λmax = 515 nm of microcrystals of solid AgCl0.95I0.05 solutions excited by a radiation flux of density 1013–1015 quanta/cm2·sec in the range 600–800 nm at 77 K was detected. It is shown that the intensity of this luminescence and the frequency of its excitation depend on the prior UV-irradiation of samples. Analysis of the stimulated-photoluminescence spectra and the anti-Stokes luminescence excitation spectra of the indicated microcrystals has shown that to the centers of anti-Stokes luminescence excitation correspond local levels in the forbidden band of the crystals. These states are apparently due to the atomic and molecular disperse silver particles that can be inherent in character or formed as a result of a low-temperature photochemical process. [ABSTRACT FROM AUTHOR]

The results of mathematical model measurements of the speed of the transverse current in the Fram Strait are presented. The method is based on the statistical processing of the propagation time fluctuations of the probing signals along 16 acoustic tracks. The dependence of the sound velocity on depth is assumed to correspond to winter conditions. For the imitation of the current, the three-dimensional field of environmental inhomogeneities observed in the strait is computed. The complex profile of the current in the direction across the strait is represented by the motion of 10 layers of this field that move with different velocities. The measuring system consists of four transmitters and four receivers positioned near both coasts of the strait. The rays used for the measurements do not touch the bottom and do not change their type under the effect of environmental inhomogeneities crossing the acoustic tracks. [ABSTRACT FROM AUTHOR]

We present the results of our study of nonlinear optical response observed in plasmon–exciton nanostructures based on PbS quantum dots passivated with thioglycolic acid and gold nanorods under the influence of 10 ns second harmonic pulses (532 nm) of Nd3+:YAG laser. We show that the association of components of a hybrid nanostructure leads to increase in the reverse saturable absorption in PbS quantum dots against the background of nonlinear refraction. Coating quantum dots with a monolayer of SiO2 reduces this effect due to blocking the process of phototransfer of charge from a quantum dot to a metal nanoparticle, which is confirmed by the quenching and reduction in the luminescence lifetime of PbS quantum dots in the presence of gold nanorods. [ABSTRACT FROM AUTHOR]

Extended abstract of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010. [ABSTRACT FROM PUBLISHER]

Abstract: The results of studies of the optical properties of ensembles of colloidal CdS quantum dots passivated by thioglycolic acid are reported. The average dimensions of the quantum dots lie in the range from 1.7 to 5.8 nm. By X-ray diffraction studies and Raman spectroscopy, it is established that quantum dots crystallize with the formation of a cubic crystal lattice. The systematic features of the quantum-confinement effect in the optical absorption and luminescence spectra, as well as in the luminescence excitation spectra, are established. The features manifest themselves as a blue shift of the corresponding bands with decreasing quantum-dot dimensions. From analysis of the nanosecond luminescence kinetics, it is concluded that experimentally observed radiative recombination proceeds by the donor-acceptor mechanism. [ABSTRACT FROM AUTHOR]

The optoacoustic method is used to evaluate local elastic anisotropy of rocks and sediments. The method is based on laser sound generation by irradiating a spot on the wall of the oil or gas borehole. The optoacoustic method offers an advantage of precise non-contact placing of a short-pulse point sound source. Pulses of a compression wave, shear waves, and a surface wave are induced in the formation as a result of optoacoustic conversion. The surface trace of the bulk compression wave propagating along the borehole surface has a velocity corresponding to that of a bulk wave. Hence, measurements of the trace propagation time along several predetermined paths on the surface of a borehole provide evaluation of local elastic anisotropy in situ. The pick-up is provided with a piezoelectric ceramic transducer positioned at a predetermined point on the surface of the borehole. The optoacoustic conversion regime parameters were chosen to provide separation of the trace pulse of another surface perturbance at the travel distance of about 0.1 m. The local measurements on the borehole wall are aimed to support accurate depth imaging of seismic data. Understanding these common anisotropy effects is important when interpreting seismic data where they are present. [ABSTRACT FROM AUTHOR]

The structure and electrical and optical properties of heterostructures formed on the surface of single-crystal silicon wafers as a result of the heat treatment and pulsed photon treatment of Ti films in oxygen, air, and nitrogen are investigated. It is shown that a TiO/TiSi/ p-Si heterostructure is formed upon heat treatment in air, whereas a TiO/TiSi/ p-Si heterostructure is formed upon photon treatment. It is established that rutile films with pronounced n-type conductivity are formed as a result of the heat treatment of Ni-doped Ti films in oxygen. Rutile films with p-type conductivity are formed upon the thermal annealing of Ti films in air with subsequent photon treatment in nitrogen. [ABSTRACT FROM AUTHOR]

Using the spectral methods of induced absorption, luminescence, and photostimulated luminescence flash, we have experimentally investigated processes of decay of electronic excitations in CdS colloidal quantum dots and in CdS/ZnS “core-shell” systems synthesized in gelatin by the sol-gel method. It has been shown that the decay of electronic excitations in colloidal quantum dots of this type is predominantly related to a fast localization of nonequilibrium charge carriers on surface defects and their subsequent recombination during times on the order of units and tens of picoseconds. The passage to core-shell systems eliminates, to a large extent, surface defects of the core, some of which are luminescence centers. However, upon using the sol-gel synthesis, a noticeable fraction of luminescence centers are formed in the interior of the CdS quantum dot, which, as well as in the case of CdS/ZnS systems, ensures localization of exciton, blocks its direct annihilation, and maintains recombination radiation. [ABSTRACT FROM AUTHOR]

We analyze the features of nonlinear refraction in colloidal solutions containing Ag2S quantum dots capped with thioglycolic acid (Ag2S/TGA) or L-cysteine (Ag2S/L-Cys), with the quantum-dot (QD) sizes ranging from 1.7 to 5.5 nm and their concentration in the solution being 0.1%. The Z-scans of the samples were obtained using 10 ns pulses of 532 nm radiation. For samples with various average sizes and positions of the characteristic feature in the optical density spectrum, both self-focusing and self-defocusing of radiation were observed. The contribution of thermal refraction to the recorded Z-scans was estimated, and the impact of thermal effects on the observed nonlinear refraction was shown to be negligible. The solutions of the Ag2S/TGA QDs with the ground state exciton absorption peaked at 590 nm exhibit self-focusing. The samples with recombination luminescence and the ground state exciton absorption peaked at 750 nm reveal self-defocusing. We show that nonlinear refraction in the case of nanosecond pulses is predominantly nonthermal in nature and is due to absorption by free charge carriers, as well as due to the band filling effect in the Ag2S QDs, which involves localized states of impurities. [ABSTRACT FROM AUTHOR]

A series of 3-R-6,8,8,9-tetramethyl-2H-pyrano[3,2-g]quinolin-2-ones was obtained by condensation of 7-hydroxy-1,2,2,4-tetramethylhydroquinoline-6-carbaldehydes with aroylacetic acid esters. The dependence of the UV and photoluminescence spectra on the structure of the obtained compounds was studied. [ABSTRACT FROM AUTHOR]

High-pulse repetition rate lasers allow significant enhancement in the average power of the low-order harmonics generation in isotropic media. We report on the third (343-nm) and fifth (206-nm) harmonics generating in air and different nanoparticle-containing laser-produced plasmas by applying Yb-doped fiber laser delivering 37-fs, 100-kHz, 1030-nm, 0.5-mJ pulses. Different characteristics of these processes (power and density dependences, influence of impeding processes, role of synthesized nanoparticles, variations of the spectral modulation of driving pulses, etc.) are analyzed. We compare the formation of the plasmas on the surfaces of aluminum, carbon, manganese, and titanium bulk species, as well as quantum dots of metal sulfides as the media for low-order harmonics generation, using 250-fs (1030-nm) and 5-ns (1064-nm) heating pulses at different delays between the heating and driving pulses. Average power of about 20 mW was estimated for the third harmonic emission from metal plasmas, with 3 × 1016 UV photons (343 nm) emitted per second. [ABSTRACT FROM AUTHOR]

The optical absorption spectra of TiO thin films with different phase compositions (anatase, rutile-brookite, anatase-rutile-brookite) are studied. The films are produced by the reactive radio-frequency magnetron sputtering of titanium in different atmospheres. It is shown that, on the assumption of the additivity of the contributions of each phase to the general spectrum with the fraction of the phase in the layer known, it is possible to use the method of subtraction of the spectra of individual phases. The fundamental absorption spectra of all of the crystal modifications detected in the multiphase films by structural studies are separated out, and the edges of the optical transitions in all of the phase components are established. [ABSTRACT FROM AUTHOR]

Abstract: Highly c-axis-oriented polycrystalline LiNbO3 films on Si(001) substrates were prepared by the radio-frequency magnetron sputtering process. Measurements of the fundamental absorption edge indicated that the optical band gap corresponds to direct and indirect transitions with energies Eg dir =4.2eV and Eg ind =2.2eV, respectively. Analysis of the Rutherford backscattering data suggested that Li atoms penetrate into silicon substrate forming inhomogeneous donor distribution. Based on the analysis of current–voltage and capacitance-voltage characteristics, the band diagram of the Si-LiNbO3 heterojunction was proposed. It was demonstrated that charge transport is affected by the barrier's properties at the heterojunction and it can be described in the framework of the Richardson–Schottky emission and Fowler–Nordheim tunneling. [Copyright &y& Elsevier]

We have observed a significant increase in the intensity with anti-Stokes excitation of recombination luminescence in AgCl(I) microcrystals sensitized by methylene blue molecules in the presence of silver nanoparticles. [ABSTRACT FROM AUTHOR]

The influence of dysprosium doping on the photoelectric and luminescent properties of AgCl crystals is studied by methods of microwave photoconductivity and photoluminescence. Doping affects both the loss kinetics of photogenerated electrons and luminescence spectra and parameters of photostimulated burst of luminescence. It is shown that the charged [Dy · V′] or neutral [Dy · 2 V′] complexes are responsible for a new luminescence band peaked at 470 nm, which manifests itself at weight concentrations of the doping additive >10%. The long-wavelength shoulder at 570 nm in the photoluminescence spectra is attributed to intracenter transitions in the Dy ions. The rate constant of the reaction of electron capture into the traps forming upon introduction of the dopant, k = (3-5) × 10 cm s, is evaluated. It is assumed that the traps are Dy dysprosium ions. [ABSTRACT FROM AUTHOR]

This study addresses the challenge of modeling temperature-dependent photoluminescence (PL) in CdS colloidal quantum dots (QD), where PL properties fluctuate with temperature, complicating traditional modeling approaches. The objective is to develop a predictive model capable of accurately capturing these variations using Long Short-Term Memory (LSTM) networks, which are well suited for managing temporal dependencies in time-series data. The methodology involved training the LSTM model on experimental time-series data of PL intensity and temperature. Through numerical simulation, the model's performance was assessed. Results demonstrated that the LSTM-based model effectively predicted PL trends under different temperature conditions. This approach could be applied in optoelectronics and quantum dot-based sensors for enhanced forecasting capabilities.

The luminescence properties of Ag 2 S quantum dots passivated with L-Cysteine (Ag 2 S/L-Cys QDs) are studied in the presence of Au nanorods passivated with cetyltrimethylammonium bromide molecules (Au/CTAB NRs). The effect of plasmonic Au/CTAB NRs on IR trap state luminescence (750 nm) is considered. It has been found that the direct interaction between the components of the plexcitonic nanostructure leads to a significant luminescence quenching of Ag 2 S/L-Cys QDs, with the luminescence lifetime being constant. This is the evidence for photoinduced charge transfer. The spatial separation of the components of plexcitonic nanostructures due to the introduction of a polymer - Poly(diallyldimethylammonium chloride) (PolyDADMAC) provides a means to change their mutual arrangement and achieve an increase in the IR trap state luminescence intensity and a decrease in the luminescence lifetime from 7.4 ns to 4.5 ns. With weak plexcitonic coupling in the nanostructures [Ag 2 S QD/L-Cys]/[PolyDADMAC]/[Au/CTAB NRs], the possibility of increasing the quantum yield of trap state luminescence for Ag 2 S QDs due to the Purcell effect has been demonstrated.

In the 20 th century, microelectronics was revolutionized by silicon-its semiconducting properties finally made it possible to reduce the size of electronic components to a few nanometers. The ability to control the semiconducting properties of Si on the nanometer scale promises a breakthrough in the development of Si-based technologies. In this paper, we present the results of our experimental studies of the photovoltaic effect in Ag 2 S QD/Si heterostructures in the short-wave infrared range. At room temperature, the Ag 2 S/Si heterostructures offer a noise-equivalent power of 1.1 × 10 -10 W/√Hz. The spectral analysis of the photoresponse of the Ag 2 S/Si heterostructures has made it possible to identify two main mechanisms behind it: the absorption of IR radiation by defects in the crystalline structure of the Ag 2 S QDs or by quantum QD-induced surface states in Si. This study has demonstrated an effective and low-cost way to create a sensitive room temperature SWIR photodetector which would be compatible with the Si complementary metal oxide semiconductor technology., Competing Interests: The authors declare no conflict of interest.

The mechanism features of colloidal quantum dots (QDs) passivation with thioglycolic acid molecules (TGA) for cases of different luminescent properties is considered using FTIR. This problem is considered based on FTIR spectra analysis for various ionic forms of TGA. Experimental TGA molecules FTIR spectra is interpreted, basing on the data on modeling of TGA vibrational modes, realized in the framework of density functional method (DFT /B3LYP/6-31+G(d)) taking into account the vibrations anharmonicity of every functional group. This approach provides a significant improvement in the agreement between the experimental and calculated data. FTIR spectra of Ag 2 S/TGA QDs with exciton and recombination luminescence are differ from each other and B "freeB" TGA molecules. The ν ( S - H ) TGA peak (2559 cm - 1 ) disappears in FTIR spectra of Ag 2 S/TGA QD samples. This fact indicates the interactions between TGA thiol group and dangling bonds of Ag 2 S nanocrystals. Ag 2 S QDs passivation with TGA molecules leads to emergence ν a s (COO - ) (1584 cm - 1 ) and ν s (COO - ) (1387 cm - 1 ) peaks. It indicates TGA adsorption in ionic form. For Ag 2 S/TGA QDs with exciton luminescence we observed (a) significant low-frequency shift of ν s (COO - ) peak from 1388 cm - 1 to 1359 cm - 1 and high-frequency shift of ν a s (COO - ) peak from 1567 cm - 1 to 1581 cm - 1 ; (b) change in the ratio of intensities of ν a s (COO - ) and ν s (COO - ) vibrations. This feature is caused by the change in the symmetry of TGA molecules due to passivation of Ag 2 S quantum dots.For Ag 2 S/TGA QDs with recombination luminescence, the insignificant high-frequency shift of 7-10 cm - 1 for ν a s (COO - ) at 1567 cm - 1 and low-frequency shift of 3-5 cm - 1 for ν s (COO - ) at 1388 cm - 1 , probably caused by the interaction of thiol with Ag 2 S surface is observed. Using FTIR spectra, it was found that IR luminescence photodegradation is also accompanied by changes in the thioglycolic acid molecules, which capped Ag 2 S QDs. In the case of Ag 2 S QDs with exciton luminescence, the degradation process is non-reversible. It is accompanied by TGA photodegradation with the formation of α -thiol-substituted acyl radical (S-CH 2 -CO • ) TGA.

The optical limiting properties of alloyed Cd 0.5 Zn 0.5 S quantum dots associated with erythrosine dye are analyzed using 532 nm, 40 ps pulses. We show that joint influence of saturable absorption, reverse saturable absorption and two-photon absorption cause the optical limiting of 532 nm radiation at the pulse energies exceeding 1 mJ. The nonlinear refraction and nonlinear absorption of these quantum dots associated with different organic dyes were studied using 1064 nm and 532 nm radiation. The nonlinear refraction index and nonlinear absorption coefficient of Cd 0.5 Zn 0.5 S quantum dots were measured at λ = 1064 nm to be 2 × 10 -13 cm 2 W -1 and 1.2 × 10 -8 cm W -1 , while the reverse saturable absorption of Cd 0.5 Zn 0.5 S quantum dots and erythrosine at λ = 532 nm was almost two orders larger. The potential applications of these quantum dots for high-order harmonic generation are discussed.

Background: An altered IL-18 pathway in patients with coronary artery disease has recently been described and this cytokine was shown to be of clinical and prognostic utility. Cardiomyocytes are a target of this cytokine which exerts inflammatory, hypertrophic and profibrotic activities., Objectives: The aim of the study was to verify the ability of IL-18 to induce expression of other pro/anti-inflammatory cytokines and to analyse the relationship between these molecules in serum from patients with heart rhythm disorders and coronary artery disease., Methods: All patients in the study were divided into two groups: with heart rhythm disorders and without but with diagnosed coronary artery disease. Heart rhythm disorders included sinus node dysfunction, bradycardia and tachycardia., Results: The interrelationships among all tested clinical, biochemical and inflammatory parameters with a dependence on median IL-18 values were checked. From all tested parameters only cytokines IL-8, IL-10 and VEGF, were associated with the serum IL-18 levels., Conclusion: IL-18, IL-8 and VEGF were identified as a factors involved in heart rhythm disorders and coronary artery disease patho-physiology and regarded as markers of prognostic significance and potential therapeutic targets. The demonstration of their in vivo relationship added new insights into the understanding of the interdependence of inflammatory pathways in patients with heart rhythm disorders or coronary artery disease., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

The atomic-level sculpting of 3D crystalline oxide nanostructures from metastable amorphous films in a scanning transmission electron microscope (STEM) is demonstrated. Strontium titanate nanostructures grow epitaxially from the crystalline substrate following the beam path. This method can be used for fabricating crystalline structures as small as 1-2 nm and the process can be observed in situ with atomic resolution. The fabrication of arbitrary shape structures via control of the position and scan speed of the electron beam is further demonstrated. Combined with broad availability of the atomic resolved electron microscopy platforms, these observations suggest the feasibility of large scale implementation of bulk atomic-level fabrication as a new enabling tool of nanoscience and technology, providing a bottom-up, atomic-level complement to 3D printing., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Advances in fabrication techniques, electronics, and mechanical cooling systems have given rise to germanium detectors suitable for biomedical imaging. We are developing a small-animal SPECT system that uses a double-sided Ge strip detector. The detector's excellent energy resolution may help to reduce scatter and simplify processing of multi-isotope imaging, while its ability to measure depth of interaction has the potential to mitigate parallax error in pinhole imaging. The detector's energy resolution is <1% FWHM at 140 keV and its spatial resolution is approximately 1.5 mm FWHM. The prototype system described has a single-pinhole collimator with a 1-mm diameter and a 70-degree opening angle with a focal length variable between 4.5 and 9 cm. Phantom images from the gantry-mounted system are presented, including the NEMA NU-2008 phantom and a hot-rod phantom. Additionally, the benefit of energy resolution is demonstrated by imaging a dual-isotope phantom with 99m Tc and 123 I without cross-talk correction.

The rich functionalities in the ABO3 perovskite oxides originate, at least in part, from the ability of the corner-connected BO6 octahedral network to host a large variety of cations through distortions and rotations. Characterizing these rotations, which have significant impact on both fundamental aspects of materials behavior and possible applications, remains a major challenge at heterointerfaces. In this work, we have developed a unique method to investigate BO6 rotation patterns in complex oxides ABO3 with unit cell resolution at heterointerfaces, where novel properties often emerge. Our method involves column shape analysis in ABF-STEM images of the ABO3 heterointerfaces taken in specific orientations. The rotating phase of BO6 octahedra can be identified for all three spatial dimensions without the need of case-by-case simulation. In several common rotation systems, quantitative measurements of all three rotation angles are now possible. Using this method, we examined interfaces between perovskites with distinct tilt systems as well as interfaces between tilted and untilted perovskites, identifying an unusual coupling behavior at the CaTiO3/LSAT interface. We believe this method will significantly improve our knowledge of complex oxide heterointerfaces.

Spatially resolved polarization switching in ferroelectric nanocapacitors was studied on the sub-25 nm scale using the first-order reversal curve (FORC) method. The chosen capacitor geometry allows both high-veracity observation of the domain structure and mapping of polarization switching in a uniform field, synergistically combining microstructural observations and probing of uniform-field polarization responses as relevant to device operation. A classical Kolmogorov-Avrami-Ishibashi model has been adapted to the voltage domain, and the individual switching dynamics of the FORC response curves are well approximated by the adapted model. The comparison with microstructures suggests a strong spatial variability of the switching dynamics inside the nanocapacitors., (© 2011 American Chemical Society)

Relaxors constitute a large class of ferroelectrics where disorder is introduced by doping with ions of different size and valence, in order to maximize their useful properties in a broad temperature range. Polarization disorder in relaxors is typically studied by dielectric and scattering techniques that do not allow direct mapping of relaxor parameters, such as correlation length or width of the relaxation time spectrum. In this paper, we introduce a novel method based on measurements of local vibrations by Piezoresponse Force Microscopy (PFM) that detects nanoscale polarization on the relaxor surface. Random polarization patterns are then analyzed via local Fast Fourier Transform (FFT) and the FFT PFM parameters, such as amplitude, correlation radius and width of the spectrum of spatial correlations, are mapped along with the conventional topography. The results are tested with transparent (Pb, La) (Zr, Ti)O₃ ceramics where local disorder is due to doping with La 3+ . The conclusions are made about the distribution of the defects responsible for relaxor behavior and the role of the grain boundaries in the macroscopic response.

We present a physical model that explains several sequential stages of the conversion of optical to acoustical energy when irradiating diluted suspensions of metal nanoparticles with laser pulses. Optical absorption and scattering of a single particle driven by plasmon resonance interactions in an aqueous medium are considered. Thermal effects produced by laser-irradiated nanoparticles, dynamics of vapor bubble formation, and acoustic signals from expanding bubbles formed around heated nanoparticles are calculated. Stochastic features of the pressure magnitude emitted as a result of low-fluence irradiation of suspensions are also discussed. The probabilistic distribution of pressure magnitude from individual bubbles was found to obey Zipf's law for low concentrations of nanoparticles, while increasing their concentration brings the pressure magnitude distribution into conformance with the Gaussian law.

A method for the estimation of the spike probability reduction caused by a preceding spike is proposed for central auditory neurons. The method is based upon a comparison of the normalized poststimulus time histogram with the normalized latency histogram and the expected probability function. For the solution of the superfluous system of linear equations, the least-squares fit was used. The result (temporal course of discharge history effect) was then approximated by a function that included several initial zero points (absolute refractory period). Three points were approximated by the error function (short relative refractory period) and all following points were equal to one. The only variable parameter was the number of zero points, the duration of refractoriness. This method was tested on a descriptive model of an auditory neuron in which each interspike interval consists of an absolute refractory period and a random-length waiting time to the next spike. The estimation of the model absolute refractory period by the proposed method was in reasonable coincidence with input data after several thousands of stimulus presentations. The same method was used for the estimation of dead-time in 87 single units of the midbrain auditory region of the frog. A great variability of refractory time (from less than 2 ms to more than 18 ms) was shown. The duration of refractoriness correlated with the latency period of neurons.