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Silicate dust particles are part of many astronomical objects such as comets and circumstellar disks. In a spectrum, silicates exhibit a number of characteristic silicate emission features. To study these features, Mie’s theory is usually used. This theory assumes that the scattering object is an ideal sphere. In this work, we investigated the contribution of non-spherical quartz particles (SiO2) to these features. We studied the influence of the deviation from sphericity on the 10-micron silicate feature of quartz. It is shown that the deviation from sphericity has a significant effect on both the scattered light intensity and the scattering factor Qsca, and this effect increases with increasing scattering particle size. The main peculiarities of the 10-micron silicate feature have been studied for both prolate and oblate spheroids.

The peak positions and halfwidths of the Q-branch of the ν1 band and the ratios of intensities of the Q-branches of ν3 and 2ν2 bands of methane are measured in a methane–helium mixture at different pressures and concentrations. An empirical model is developed for estimation of the He concentration in a methane-containing medium from measurements of the above parameters. The error in the He concentration is found to be less than 1% when using the ν1 band halfwidth. The paths of improvement of this technique and enhancement of its accuracy are considered.

Morphology, structure, magnetic properties and magnetic circular dichroism (MCD) were studied for the FexSy and FexSey nanoparticles (NPs) synthesized with the polyol mediated and the thermal decomposition processes, correspondingly, at different regimes. For all NPs samples, but Fe3S4, MCD was measured for the first time. It has been shown that in the case of sulfides, the character of the MCD spectrum changes as the NPs phase composition transforms from Fe3S4 to FeS with the synthesis temperature increase. At the same time, the shape of the MCD spectrum is almost independent of the NPs phase in the case of iron selenides

Raman spectroscopy is a promising tool for combustion processes optimization, due to the possibility of rapid determination of the exhaust gases composition. An important gas component in this task is carbon monoxide whose emission limits vary from 100 to 200 parts per million (ppm), depending on the heat generator technology. However, for the correct determination of its concentration from the sample Raman spectrum, it is necessary to take into account the contribution of nitrogen lines intensity due to their mutual overlap. This paper discusses a technique for deriving carbon monoxide intensity based on fitting the nitrogen spectrum at various temperatures. It is shown that ignoring the Herman–Wallis factors in the fitting procedure lead to an additional measurement error, which increases with temperature and exceeds 350 ppm at T = 1800 K.

Raman spectroscopy is a unique tool for fast analysis of multicomponent gas media. In this work, we studied the features of application of this method for monitoring the syngas (mixture of CO + H2 + CH4 + CO2 + N2) composition. To determine concentrations, we used contour fit method, where the Raman spectrum of mixture is compared with a synthetically calculated spectrum. The effects of pressure changes and various exposure times on the accuracy of measurements are investigated. It was found that effect of pressure and environment on band contours results in measurement errors several times higher than the errors caused by deviations of the signal intensities.

There is great interest in the development of renewable and environmentally friendly fuel sources such as biogas and syngas for generation of heat and electricity. Raman spectroscopy is a promising method for rapid quantitative analysis of the composition of such gases. To improve the accuracy of the method, information is needed on changes in the spectra of the main components as a function of pressure and gas composition. In this work the spectral characteristics of the most intense peaks of methane, carbon monoxide, carbon dioxide and hydrogen in the range of 200–3800 cm−1 were investigated in the range of 1–25 bar for pure gases and binary mixtures. It has been revealed that, under these conditions, the change in the characteristics of pure rotational hydrogen lines is negligible, while the Q-branches of the main vibrational bands of methane, carbon monoxide and carbon dioxide shift to a few tenths of cm−1. The values of errors that can occur in the case of ignoring such changes in the spectra are estimated.

Study of the effect of molecular hydrogen on the behavior adaptation of chinchilla in conditions of cage keeping. The experimental animals received drinking water enriched with molecular hydrogen at a dosage of 0.1-1.1 ppm for 10 months. It was found that the peak of activity of the behavior of chinchillas of both groups fell on the period from 19:00 to 9:00. A significant difference between the experimental and control groups were identified by the shape of behavior “movement within the cage” activity in experimental group daytime was higher at 24 minutes (p˂0.05) than in the control. The dynamics of daily activity of experimental animals came eh for the period from 19:00 to 08:00 (on average by 12 minutes) and the control group - 22:00-08:00 (an average of 6 minutes). The introduction of drinking water enriched with molecular hydrogen into the diet of the experimental group of chinchillas for 10 months increased the proportion of active behavior of animals by 20.6%.

It was found that the inclusion of water enriched with molecular hydrogen into the diet of a long-tailed chinchilla changed the fur quality indicators. In animals of the experimental group, the guard and downy hairs were thinner than in the control group. The length of downy hair in the experimental group was higher, the number of hairs in the follicle in the chinchillas of the experimental group was greater than in the control group, besides, the hair was stronger and softer. The animals of the experimental group showed less tendency to gnaw out fur. When considering the data on the chemical composition, it was found that in the dry matter of the hair of the animals of the experimental group, there were less organic substances, and there were more minerals in comparison with the animals of the control group.

The present state of laser glasses production for optoelectronic systems and devices is considered. The limitations of existing laser glasses and the necessity to create new ones have been viewed. The urgency of the development and introduction of new types of laser glass for its use in both civilian and defense equipment sectors is shown. The technological complexity of the phosphate erbium glasses production is substantiated. The purpose of the work is to create laser glasses and make a laser element, will be operating wavelength of 1.54 μm. Optimum concentration of rare earth oxides in laser glasses has been determined. The quality control methodology and technology of laser glasses were developed. The production of a new laser glass makes it possible to use it in modern optoelectronic systems. The laser elements were fabricated and their generation characteristics were investigated. The results of the laser elements industrial testing are presented.

Pressure effects on the Raman spectrum of gaseous propane in methane are investigated. It is found that propane Raman bands located in the range 2700–3100 cm–1 shift to lower frequencies although Raman bands in the range 300–1600 cm–1 change negligibly as the density of the medium containing the analyzed propane increases.

We have studied the particular features of the Raman spectra of gaseous n-butane, isobutane, n-pentane, and isopentane in a methane medium at a pressure of 25 atm. It has been found that, under these conditions, changes in the conformational equilibria of these molecules are negligible, and most significant changes in the spectra are observed in the range of 2850–3000 cm–1, in which bands corresponding to the stretching vibrations of CH2 and CH3 groups shift to lower frequencies. The data obtained will be usefull in determining the composition of natural gas using Raman spectroscopy.

The paper demonstrates the possibility of measuring the carbon dioxide (CO2) concentration in atmospheric air using Raman spectroscopy. Three methods have been studied for deriving the CO2 concentration from the Raman spectra (the peak intensity ratio, the integrated intensity ratio, the contour fit method). The best results were obtained when the contour fit method is applied for Raman spectra processing. In this case the deviations from reference mixtures of known concentration were below 3 ppm. Methods for improving the sensitivity of the Raman gas analysis method are proposed and the possibility for using this technique for the simultaneous determination of the concentrations of significant amount of greenhouse gases in air with single device is discussed.

Tuning optical or magnetic properties of nanoparticles, by addition of impurities, for specific applications is usually achieved at the cost of band gap and work function reduction. Additionally, conventional strategies to develop nanoparticles with a large band gap also encounter problems of phase separation and poor crystallinity at high alloying degree. Addressing the aforementioned trade-offs, here we report Ni-Zn nanoferrites with energy band gap (Eg) of ≈3.20 eV and a work function of ≈5.88 eV. While changes in the magnetoplasmonic properties of the Ni-Zn ferrite were successfully achieved with the incorporation of bismuth ions at different concentrations, there was no alteration of the band gap and work function in the developed Ni-Zn ferrite. This suggests that with the addition of minute impurities to ferrites, independent of their changes in the band gap and work function, one can tune their magnetic and optical properties, which is desired in a wide range of applications such as nanobiosensing, nanoparticle based catalysis, and renewable energy generation using nanotechnology.

The influence of temperature in the range 20–40oC on the main vibrational-rotational Raman bands (ν1, ν2, ν3, 2ν2, and 2ν4) of methane was investigated. An increase of temperature caused the frequencies of the Q-branches to shift differently and the relative intensities of the 2ν2 and 2ν4 overtones that were in Fermi resonance with ν1 to decrease. A method for determining the temperature of a methane-containing gaseous medium was proposed. The impact of temperature fluctuations on results from Raman analyses of natural-gas compositions was estimated.

Results of investigation of changing peak positions, half widths, and peak intensities of Q-branches of the ν2, 2ν4, ν1, ν3, and 2ν2 methane Raman bands are presented at pressures in the range 1–55 bar and а temperature of 298 K. The peak position of the ν2 band remains practically unchanged, and peak positions of all other bands, by analogy with the ν1 band, are shifted toward lower wavenumbers with pressure increase. It is demonstrated that the peak intensity ratio of any pair of the previously enumerated bands (except the pair of 2ν4 and 2ν2) is sensitive to pressure changes. When pressure increases, the decreased peak intensities of Q-branches of depolarized ν2 and ν3 bands are caused by broadening of their rotational–vibrational lines, and the increased peak intensities of Q-branches of the 2ν4 and 2ν2 bands are most likely caused by their increased interaction with the ν1 and ν3 bands. A set of data obtained will be useful for the Raman analysis of natural gas and can also be used for determination of the pressure of methane-containing media. Copyright © 2017 John Wiley & Sons, Ltd.

The effect of methane environment and increased pressure (up to 25 bar) on the stability of the conformational equilibrium of gaseous n-butane was investigated using Raman spectroscopy. It is established that under these conditions the change in the concentration of trans and gauche-conformers of n-butane is less than 1%. The results obtained will be useful for Raman diagnostics of natural gas composition.

The main components of the synthesis gas are hydrogen, carbon monoxide, methane and carbon dioxide. In this work, we studied the spectral characteristics of the most intensive Raman bands of these components as a function of environment at a fixed pressure of 25 bar. It has been established that, under these conditions, the change in the characteristics of pure rotational hydrogen lines is negligible, and the vibrational bands of methane, carbon monoxide and carbon dioxide shift to a few tenths of cm–1. The data obtained allow to improve the accuracy of determining the composition of the synthesis gas using Raman spectroscopy.

At present gas analysis based on Raman, spectroscopy is actively developed. In most cases, to achieve the required Raman signal intensity, compression of the gas medium is used. However, in comparison with normal conditions, the character of motion of molecules and their electric properties change in high-pressure gas media, thereby violating a linear dependence of the Raman signal intensity on the concentration of molecules and the gas pressure. In the present work, a theoretical model is presented that describes the Raman signal intensity as a function of the pressure of the gas medium considering the compressibility factor, the internal field factor, and the instrumental factor. To verify the model, changes in the Raman signal intensities of vibrational bands of nitrogen and oxygen in the pressure range 1–80 atm and carbon dioxide in the pressure range 1–60 atm are investigated. Under these conditions, we observe a deviation of ~3% from a linear dependence for nitrogen, ~7% for oxygen and ~80% for carbon dioxide, which is in good agreement with the theoretical model. Raman shifts, half-widths of Q-branches of vibrational bands ν1 (and 2ν2 for carbon dioxide) of these molecules and also ratio of integral intensities I(2ν2)/I(ν1) for carbon dioxide under these conditions are investigated. Copyright © 2016 John Wiley & Sons, Ltd.

In the present work, an improved model of the Raman gas analyzer (RGA) of natural gas (NG) developed by us is described together with its operating principle. The sensitivity has been improved and the number of measurable gases has been expanded. Results of its approbation on a real NG sample are presented for different measurement times. A comparison of the data obtained with the results of chromatographic analysis demonstrates their good agreement. The time stability of the results obtained using this model is analyzed. It is experimentally established that the given RGA can reliably determine the content of all molecular NG components whose content exceeds 0.005% for 100 s; moreover, in this case the limiting sensitivity for some NG components is equal to 0.002%.

It was found that the inclusion of water enriched with molecular hydrogen in the diet of animals increased the overall proportion of active behavior. According to the form of behavior "moving around the cage", it was found that males and females of the experimental group spent more time than animals of the control group. Males of the experimental group were 24% more active at night, and females were 60% more active than in the control group. In the daily dynamics, the period of activity of animals in the experimental group was from 19:00 to 8:00, and in the control group-from 22:00 to 8:00. In the daily balance according to the form of behavior "moving around the cage", chinchillas of the experimental group spent 5% more than in the control group.

Silicate dust particles are part of many astronomical objects such as comets and circumstellar discs. In the spectrum, silicates exhibit a number of characteristic emission features. In this paper, we studied the contribution of quartz (SiO2) particles to these features. Using the Mie theory, calculations were made of the intensity of light scattered by such particles. Two spectral features were found in the spectrum—near 9 μm and near 20.5 μm. The main properties of these features are investigated. It is established, that the 9 μm feature is much narrower than the 20.5 μm; with an increase in the size of the scattering particle from very small values the position of spectral features (both 9 μm and 20.5 μm) shifts toward longer wavelengths; the 9 μm feature cannot be clearly seen with particle sizes greater than 18 μm, while the 20.5 μm feature is apparent even at particle radius 60 μm.

In this work, we measured the intensities of Q-branches of the &nu, 1, &nu, 2 and &nu, 3 bands in the polarized and depolarized methane Raman spectra in the pressure range of 1&ndash, 60 atm. It was established that the pressure dependence of depolarization ratios of the &nu, 3 bands are negligible. In turn, the depolarization ratio of the &nu, 1 band increases with increasing pressure and reaches approximately 0.0045 at 60 atm. These data are more precise than previously published ones because &nu, 1 band intensities were determined taking into account the contribution of overlapping lines of &nu, 3 band. The presented data will be useful in calculating the methane polarizabilities at high pressure, as well as in calculating methane Raman spectra for measuring the natural gas composition using Raman spectroscopy.

Alzheimer's disease (AD) is a degenerative neurological disorder that is the most common cause of dementia and disability in older patients. Available treatments are symptomatic in nature and are only sufficient to improve the quality of life of AD patients temporarily. A potential strategy, currently under investigation, is to target cell-signaling pathways associated with neurodegeneration, in order to decrease neuroinflammation, excitotoxicity, and to improve cognitive functions. Current review centers on the role of neuroinflammation and the specific contribution of mast cells to AD pathophysiology. The authors look at masitinib therapy and the evidence presented through preclinical and clinical trials. Dual actions of masitinib as an inhibitor of mast cell-glia axis and a Fyn kinase blocker are discussed in the context of AD pathology. Masitinib is in Phase III clinical trials for the treatment of malignant melanoma, mastocytosis, multiple myeloma, gastrointestinal cancer and pancreatic cancer. It is also in Phase II/III clinical trials for the treatment of multiple sclerosis, rheumatoid arthritis and AD. Additional research is warranted to better investigate the potential effects of masitinib in combination with other drugs employed in AD treatment.

Previous studies suggest that Alzheimer's disease (AD) neurobiology could not be explained solely by an increase in β-amyloid levels. Recently, it has been proposed that alterations in brain cholesterol metabolism may contribute to the pathogenesis of AD. In the present work, we focus on early changes in the hippocampal phenotypes of two mouse models in which cognitive impairments were previously described: a) the hypercholesterolemic LDL receptor knockout (LDLr -/-) and b) the APPswe/PS1dE9 (APP/PS1) transgenic model of familial AD. Our initial analysis, subsequent validation and additional experiments at the mRNA and protein levels demonstrate some parallels between the hippocampal phenotypes of these 2 mouse models, however our data suggest that the molecular mechanisms leading to cognitive decline are distinct in LDLr -/- and APP/PS1 animals. Genes related to cytokine signaling were significantly down-regulated in LDLr -/- mice when compared to both the wild-type and APP/PS1 mice, and these include prostaglandin-endoperoxide synthases 1 and 2 (ptgs1 and 2) and nerve grow factor (ngf). We have also detected reduced expression of genes related to lipid metabolism in LDLr -/- mice: peroxisome proliferator activated receptor gamma (pparg), pro-opiomelanocortin-alpha (pomc) and of protein kinase, AMP-activated, alpha 1 catalytic subunit of AMPK (prkaa1). Our array data also indicate that transcriptional activity of early genes involved in memory process, such as FBJ osteosarcoma oncogene (Fos) and the activity regulated cytoskeletal-associated protein (Arc) gene, are increased in the hippocampus of LDLr -/- mice. Several proteins like insulin degrading enzyme (IDE), PGC-1α, OXPHOS 1, NMDAR1 and cyclic AMP response element binding protein (CREB) are up-regulated in the LDLr -/- mice, while in the APP/PS1 mouse model only OXPHOS complexes 2, 3 and 5 are slightly downregulated. Further studies are necessary to understand the molecular pathways involved in memory loss in hypercholesterolemic LDLr -/- mice.

We have developed a spectrometer designed to record spontaneous Raman scattering (SRS) spectra in gaseous media. The spectrometer has improved sensitivity due to using a high-performance spectral instrument and also a device for compressing the analyte gaseous medium. We present the results of an experimental test of the spectrometer, and show that its limiting sensitivity for methane is

The present work focuses on the influence of CH4 environment on the changes in Raman spectra of n-C5H12 and i-C5H12 in the gaseous phase. It was found that in binary gas mixtures with an overwhelming content of CH4, the majority of the n-C5H12 and i-C5H12 Raman bands shifted toward lower wavenumbers. Moreover, there is also a redistribution of intensities between certain Raman bands of n-C5H12 and i-C5H12. The obtained results will be essential for Raman diagnostics of natural gas composition.

The study is dedicated to the problems of wavenumber calibration of multichannel Raman spectrometers. We present a calibration method based on the combined use of the neon emission spectrum and pure rotational lines of the hydrogen Raman spectrum.

Using binary CH4 - mixtures with varied concentrations of H2, N2, CO2, C2H6 and C3H8 and a fixed ambient pressure of 25 bar, the influence of the environment on spectral characteristics (Raman shift, half-width, peak intensity) of Q-branches of the ν1, ν2, ν3, and 2ν4 methane Raman bands are investigated. It is found that depending on the environment these bands demonstrate different changes in their Raman shifts and half-widths. It is shown that the ratios of peak intensities I(ν2)/I(ν1), I(ν3)/I(ν1) and I(2ν4)/I(ν1) are very sensitive to the environment. The Raman shifts and half-widths of CH4 bands are assumed to depend on the absolute concentration of molecules in the analyzed medium. The data obtained would be useful in Raman diagnostics of natural gas.

Amyotrophic lateral sclerosis (ALS) is a devastating condition with an estimated mortality of 30,000 patients a year worldwide. The median reported survival time since onset ranges from 24 to 48 months. Riluzole is the only currently approved mildly efficacious treatment. Riluzole received marketing authorization in 1995 in the USA and in 1996 in Europe. In the years that followed, over 60 molecules have been investigated as a possible treatment for ALS. Despite significant research efforts, the overwhelming majority of human clinical trials (CTs) have failed to demonstrate clinical efficacy. In the past year, oral masitinib and intravenous edaravone have emerged as promising new therapeutics with claimed efficacy in CTs in ALS patients. Given their advanced phase of clinical development one may consider these drugs as the most likely near-term additions to the therapeutic arsenal available for patients with ALS. In terms of patient inclusion, CT with masitinib recruited a wider, more representative, less restrictive patient population in comparison to the only successful edaravone CT (edaravone eligibility criteria represents only 18% of masitinib study patients). The present manuscript reviews >50 CTs conducted in the last 20 years since riluzole was first approved. A special emphasis is put on the analysis of existing evidence in support of the clinical efficacy of edaravone and masitinib and the possible implications of an eventual marketing authorisation in the treatment of ALS.

Nowadays the sources of long-wavelength optical radiation (far infrared, terahertz range) are developed intensively. They have good perspectives in different fields of biology, medicine, security systems etc. This implies the need to have the detectors of radiation with advanced parameters 1,2. Golay cell 3 is one of the most sensitive detector types available at the time being despite, the strong development of semiconductor detectors 4 – 6. In Golay cell the energy is measured by the expansion of the gas in the sealed chamber: the gas absorbs the energy and presses the flexible membrane, thus the change of volume is registered. The disadvantages of these detectors are relatively high price, big size and vibration susceptibility. In our paper we consider the method of radiation detecting that is similar to one that is used in Golay cell but based on gas temperature measurement.

In the present work, the method of evaluation of component composition of natural gas is based on the decomposition of Raman spectrum into spectra of the individual components is described. To implementing of this method the spectral ranges 250-2500 cm -1 and 3600-3700 cm -1 were selected. The Raman spectra of the main components of natural gas are presented. Results of Raman gas analyzer approbation on a real natural gas sample are presented. A comparison of the experimental results obtained with the results of chromatographic analysis demonstrates their good agreement. It is experimentally established that the given Raman gas analyzer can reliably determine the content of all molecular natural gas components whose content exceeds 0.005% for 100 s.

It is shown that the main problem, arising when designing a stationary Raman gas analyzer intended to monitor gaseous air pollutions, is to get SRS signals of sufficient intensity. The engineering solutions are presented that provide the required sensitivity (~ 50–100 ppb). It is achieved by compressing a gas medium under analysis and gaining intensity of the exciting laser radiation.

A prototype of a stationary Raman gas analyzer with the improved sensitivity is described. The improvement is provided by using both a device for compressing analyzed gas media and a specialized effective spectral device as a part of the gas analyzer. The experimental testing of the modified Raman gas analyzer was performed in the probing of atmospheric air that confirmed the extreme sensitivity of the prototype was equal to ~ 1 ppm.

A major unresolved issue in the Parkinson's disease (PD) treatment is the development of l-DOPA-induced dyskinesias (LIDs) as a side effect of chronic L-DOPA administration. Currently, LIDs are managed in part by reducing the L-DOPA dose or by the administration of amantadine. However, this treatment is only partially effective. A potential strategy, currently under investigation, is the coadministration of metabotropic glutamate receptor 5 (mGluR5) negative allosteric modulators (NAMs) and L-DOPA; a treatment that results in the improvement of dyskinesia symptoms and that permits reductions in l-DOPA dosage frequency.The authors examine the role of mGluR5 in the pathophysiology of PD and the potential use of mGluR5 NAM as an adjuvant therapy together with a primary treatment with L-DOPA. Specifically, the authors look at the mavoglurant therapy and the evidence presented through preclinical and clinical trials.Interaction between mGluR5 NAM and L-DOPA is an area of interest in PD research as concomitant treatment results in the improvement of LID symptoms in humans, thus enhancing the patient's quality of life. However, few months ago, Novartis decided to discontinue clinical trials of mavoglurant for the treatment of LID, due to the lack of efficacy demonstrated in trials NCT01385592 and NCT01491529, although no safety concerns were involved in this decision. Nevertheless, the potential application of mGluR5 antagonists as neuroprotective agents must be considered and further studies are warranted to better investigate their potential.

We studied features of Raman scattering and the third-harmonic generation in silicon nanowire (SiNW) ensembles formed by means of chemical etching of crystalline silicon (c-Si) wafers with preliminary deposited silver nanoparticles in hydrofluoric acid. The c-Si wafers of different crystallographic orientations and doping levels were used, which results in variations of the formed nanostructure size and degree of order. For the excitation at 1064 nm the ratio of Raman scattering signals for SiNWs and those for initial c-Si wafer ranges from 2 to 5, whereas for shorter wavelengths the ratio increases for more ordered arrays of SiNWs of greater diameter and decreases for less ordered SiNW structures. The TH signals in SiNW ensembles demonstrate both fall and one- or two-orders-of-magnitude rise in comparison with c-Si depending on the structure of the SiNW ensemble. The obtained results are explained by the effect of partial light localization in SiNW ensembles.

We study the structure and optical properties of arrays of silicon nanowires (SiNWs) with a mean diameter of approximately 100 nm and length of about 1-25 μm formed on crystalline silicon (c-Si) substrates by using metal-assisted chemical etching in hydrofluoric acid solutions. In the middle infrared spectral region, the reflectance and transmittance of the formed SiNW arrays can be described in the framework of an effective medium with the effective refractive index of about 1.3 (porosity, approximately 75%), while a strong light scattering for wavelength of 0.3 ÷ 1 μm results in a decrease of the total reflectance of 1%-5%, which cannot be described in the effective medium approximation. The Raman scattering intensity under excitation at approximately 1 μm increases strongly in the sample with SiNWs in comparison with that in c-Si substrate. This effect is related to an increase of the light-matter interaction time due to the strong scattering of the excitation light in SiNW array. The prepared SiNWs are discussed as a kind of 'black silicon', which can be formed in a large scale and can be used for photonic applications as well as in molecular sensing.

The derivation of the Sh-matrices using the T-matrix method allows the shape-dependent parameters to be separated from size- and refractive-index-dependent parameters. This separation also allows for the surface integrals to be solved and for analytic solutions to the light-scattering from some irregular morphologies to be found. In this manuscript we derive solutions for capsule-shaped and bi-sphere particles. We analyze the two-dimensional patterns resulting from these two different simulants of B. subtilis spores. The large differences between the patterns suggest that simple approximations to complicated particles may not be adequate.

A comparison of acoustooptic efficiency in both Ti:LiNbO3 and GaAlAs waveguides is made with the help of known results and additional experiments. It is shown that the acoustooptic figure of merit for the frequency of 100 MHz in a GaAlAs waveguide is one order of magnitude higher than in Ti:LiNbO3 waveguide.