40 results on '"Vladimir Y. Zaitsev"'
Search Results
2. Nonlinear acoustics in studies of structural features of materials
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Vladimir Y. Zaitsev
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Materials science ,business.industry ,Linear elasticity ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Microstructure ,01 natural sciences ,Amorphous solid ,Moduli ,Nonlinear system ,Nonlinear acoustics ,Nondestructive testing ,Lattice (order) ,0103 physical sciences ,General Materials Science ,Statistical physics ,Physical and Theoretical Chemistry ,0210 nano-technology ,business ,010301 acoustics - Abstract
Linear elastic moduli of solids with similar chemical compositions usually vary fairly insignificantly. However, for a broad class of apparently similar materials, their higher-order (nonlinear) moduli may differ by many times or even by orders of magnitude. Besides their large magnitude, nonlinear effects often demonstrate qualitative/functional features inconsistent with predictions of the classical theory of nonlinear elasticity based on consideration of weak lattice (atomic) nonlinearity. The latter is mostly applicable to ideal crystals and flawless amorphous solids, whereas the presence of structural heterogeneities can drastically modify the acoustic nonlinearity of materials without appreciable variation in the linear elastic properties. Despite often rather nontrivial/nonstraightforward relationships between microstructural features of the material and the resultant “nonclassical” acoustic nonlinearity, the extremely high structural sensitivity makes utilization of nonlinear acoustic effects attractive for a broad range of diagnostic applications that have been emerging in recent years in various areas—from seismic sounding and nondestructive testing to materials characterization down to the nanoscale.
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- 2019
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3. Spatially-resolved slow dynamics of strains due to residual stresses in cartilaginous implants visualized by phase-sensitive optical coherence tomography
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Alexander L. Matveyev, Alexander A. Sovetsky, Emil N. Sobol, Yulia M. Alexandrovskaya, Vladimir Y. Zaitsev, Olga I. Baum, and Lev A. Matveev
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Materials science ,medicine.anatomical_structure ,Optical coherence tomography ,medicine.diagnostic_test ,Residual stress ,Cartilage ,medicine ,Stress relaxation ,Relaxation (physics) ,Shape-memory alloy ,Elastography ,Deformation (engineering) ,Biomedical engineering - Abstract
Laser-assisted relaxation of internal stresses can be used to stabilize the new shape of cartilaginous implants. The ability of cartilage tissue to experience irreversible deformation under certain conditions, as well as to restore its original configuration after external mechanical stress, is studied in near real time using a new method of optical coherent elastography (OCE), developed to visualize slow deformation. The OCE technique allows one to monitor the efficiency of laser-induced stress relaxation at 1–2 minute intervals using 2D subsurface strain mapping. It has been shown that the redistribution of the interstitial fluid due to the applied load is an important factor for the mechanism of "shape memory" of the cartilage. Deviations in the behavior of cartilage from the usual elastic properties of homogeneous materials, such as subsurface dilatation opposing the applied load, are identified and analyzed.
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- 2021
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4. Assessing elastic properties of cracks in rock samples subjected to thermo-hydro-chemo-mechanical damage
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Tiziana Vanorio, Anthony C. Clark, Andrey V. Radostin, and Vladimir Y. Zaitsev
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Materials science ,Chemo mechanical ,Composite material - Abstract
An understanding of micro- and macrofracture behavior in low porosity rocks is pertinent to several areas of energy and environmental science such as petroleum production, carbon sequestration, and enhancement of technologies based on geothermal energy, etc. For example, the carbonate reservoirs in dolomitic or micritic formations with matrix porosities below 6% suggest the importance of fracture-augmented permeability in production. Similarly, hydrocarbons have been found on nearly every continent in tight basement rocks, all of which have little matrix porosity and their permeability therefore rely solely on hydraulic connectivity from fractures. For geothermal energy, various igneous and sedimentary rocks (granites, basalts, and limestones) are being exploited across the globe, with some of the lowest porosity and permeability. In all these cases, fractures are necessary to improve rock permeability and thermal exchange between the rock and working fluid, which can be enabled by hydraulic stimulation, as well as by secondary cracking due to extreme temperature gradients from the injection of cold water. The fracture geometry, density, and distribution all together control not only fluid and thermal transport in the rocks, but also their seismic attributes that can be used to extract information about the fractures. In order to accurately interpret the seismo-acoustic data (usually, the velocities of compression and shear waves) reliable rock physics models are required. Here, we report the results of interpretation of such experimental data for both as-cored rock samples and those subjected to thermo-hydro-chemo-mechanical damage (THCMD) in the laboratory. For interpretation, we use a convenient model of fractured rock in which fractures are represented as planar defects with decoupled shear and normal compliances. The application of such an approach makes it possible to assess and compare the elastic properties of fractures in the rocks before and after application of THCMD procedures. For the analyzed samples of granites, basalts, and limestones it has been found that for a significant portion of rocks, the ratio of normal-to-shear compliances of cracks significantly differ from the value typical of conventionally assumed penny-shape cracks. Furthermore, for some samples, this ratio appears to be noticeably different for fractures existing in the as-cored rock and arising in the same rock after THCMD procedures. These results indicate that damage to a rock typically changes its compliance ratio since the old and new cracks are likely to have different elastic properties. Our results are also consistent with the notion that a specific damage process occurring for a given microstructure will consistently create cracks with a particular set of elastic properties. The proposed methodology for assessment of elastic properties of cracks in rock samples subjected to thermo-hydro-chemo-mechanical damage has given previously inaccessible useful information about the elastic properties of fractures and can be extended to interpretation of seismic attributes of rocks for a broad range of other applications.
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- 2021
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5. Quantitative Mapping of Strains and Young Modulus Based on Phase-Sensitive OCT
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Vladimir Y. Zaitsev, Alexander A. Sovetsky, Alexander L. Matveyev, and Lev A. Matveev
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symbols.namesake ,Materials science ,Phase sensitive ,InformationSystems_INFORMATIONSTORAGEANDRETRIEVAL ,symbols ,Young's modulus ,Composite material ,GeneralLiterature_REFERENCE(e.g.,dictionaries,encyclopedias,glossaries) - Published
- 2020
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6. Compressional optical coherence elastography as a tool for feasible in vivo histology-like morphological segmentation of cancer-tissue constituents
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Ekaterina V. Gubarkova, Alexander L. Matveyev, Vladimir Y. Zaitsev, Alexander A. Sovetsky, Natalia D. Gladkova, Anton A. Plekhanov, Elena V. Zagaynova, S.S. Kuznetsov, Marina A. Sirotkina, and Lev A. Matveev
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Specific modulus ,Optical coherence elastography ,Materials science ,Murine tumor ,In vivo ,medicine ,Stiffness ,Segmentation ,Histology ,medicine.symptom ,Morphological segmentation ,Biomedical engineering - Abstract
We report a new application of compressional optical coherence elastography (OCE) to discriminate morphological constituents of biological tissues by analyzing OCE images obtained either in vivo or for freshly excised samples. The new technique enables quantitative morphological segmentation of OCE images with delineation of several (~4-6) tissue constituents. As the first step, the method uses compressional OCE to reconstruct stiffness maps for a pre-chosen standardized pressure over the entire area of the OCE image. Then specific stiffness ranges (characteristic "stiffness spectra") are initially determined by careful comparison of the OCE-based stiffness maps with the results of segmentation of "gold-standard" histological slices. After such pre-calibration, the stiffness maps can be automatically segmented into regions, for which the Young’s modulus (stiffness) falls in specific ranges corresponding to the morphological constituents to be discriminated. The results of such automated segmentation of OCE-images demonstrate a striking correlation with the results of conventional segmentation of histological slices in terms of percentages of the segmented zones. High sensitivity of the OCE-method to histological alterations was demonstrated in vivo in comparative studies of various types of anti-tumor therapies using murine tumor models. Studies of >100 samples of freshly excised breast cancer samples revealed strong correlation between the tumor-tissue subtype and its morphological composition determined by the developed OCE method. Thus, the developed approach can be used as a basis for express OCE-based biopsy (feasible intraoperatively). Longitudinal in vivo monitoring of morphological alterations in tumors under therapy or during natural development is also possible for locations accessible to OCT.
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- 2020
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7. Optical coherence elastography for characterization of natural interstitial gaps and laser-irradiation-produced porosity in corneal and cartilaginous samples
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A. V. Yuzhakov, Lev A. Matveev, Emil N. Sobol, Alexander A. Sovetsky, Olga I. Baum, Alexander Omelchenko, Vladimir Y. Zaitsev, and Alexander L. Matveyev
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Materials science ,Modulus ,Stiffness ,Context (language use) ,Young's modulus ,Compression (physics) ,symbols.namesake ,symbols ,medicine ,Fiber ,medicine.symptom ,Composite material ,Porosity ,Elastic modulus - Abstract
We use novel possibilities opened by compressional Optical Coherence Elastography (OCE) to characterize both natural interstitial gaps and laser-irradiation-produced porosity in collagenous tissues (corne and cartilage). Under increasing moderate compression up to strains ~several percent, the current Young modulus of cornea gradually increases from initial values below 100 kPa to values >MPa that are closer to Young's modulus of cartilages in which collagen fibers are much denser packed. The lower stiffness of cornea can reasonably be attributed to the initially looser packed collagenous fiber layers, so that initial high compressibility of cornea is dominated by interlayer voids (gaps). By analogy with geophysics, we apply a model describing the reduction in the tissue elastic modulus due to the presence of a system of nearly parallel, thin "crack-like" voids/pores between the collagenous fiber layers. Initially they are highly compressible, but with increasing compression are getting closed, so that the material gets stiffer. Characterization of such porous component in water-saturated packing of collagenous layers in the natural state is inaccessible to AFM and conventional microscopy, whereas OCE enables earlier unavailable possibility to non-invasively characterize such pores/gaps (their total volume and distribution over the aspect ratio) by analogy with crack characterization in geophysics. Also we apply OCE to characterize spatially-inhomogenous modification of pore characteristics by moderate IR-laser-irradiation in regimes typical of collagenous-tissue reshaping. The obtained results are important for obtaining better insight in the structural modificatons in collagenous packings in the context of the development of novel methods of laser-assisted non-surgical methods of cornea-refraction correction and biologically non-destructive reshaping of cartilaginous samples for fabrication of implants in otolaryngology and maxillofacial surgery.
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- 2020
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8. Characterization of elastic nonlinear properties of the tissues using compressional optical coherence elastography
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Alexander A. Sovetsky, Natalia D. Gladkova, Vladimir Y. Zaitsev, A. L. Matveyev, Ekaterina V. Gubarkova, and Lev A. Matveev
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Materials science ,medicine.diagnostic_test ,Young's modulus ,Characterization (materials science) ,Stress (mechanics) ,symbols.namesake ,Optical coherence elastography ,Nonlinear system ,Optical coherence tomography ,Nonlinear parameters ,symbols ,medicine ,Elastography ,Biomedical engineering - Abstract
Compressional optical coherence elastography (OCE) is the emerging tool to evaluate Young modulus of the tissue with resolution close to optical coherence tomography. Recent versions of compressional OCE based on the strain comparison within the tissue and the calibrated reference silicone layer (sensor) located between the OCT probe and tissue. For standard realizations of compressional OCE the evaluation of the strain within the tissue and the sensor performed only at one point of the stress-strain curve. In the same way the applied stress can be easily estimated in a wide range on the base on the stress-strain relation for calibrated sensor strain that allow to evaluate the stress-strain relation for the underlying tissue not in one point but in the wider range. In this report we demonstrate this approach to nonlinear parameter evaluation for wide range of the tissues. We demonstrate the application of this new tool to breast tissue, vaginal wall, bladder, brain, cartilages, coronary arteries walls in various states. The preliminary results shows that several states of the tissues such as vaginal wall state in case of pelvic organ prolapse, benign breast tumor and coronary arteries plague can be determined on the base of elastic nonlinear parameters.
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- 2020
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9. OCT-based strain mapping and compression optical coherence elastography to study and control laser-assisted modification of avascular collagenous tissues
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A. V. Yuzhakov, Vladimir Y. Zaitsev, Alexander L. Matveyev, Emil N. Sobol, Alexander I. Omelchenko, Lev A. Matveev, Olga I. Baum, and Alexander A. Sovetsky
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Materials science ,genetic structures ,medicine.diagnostic_test ,Strain mapping ,Compression (physics) ,Laser ,Laser assisted ,eye diseases ,law.invention ,Optical coherence elastography ,Corneal edema ,law ,medicine ,Elastography ,Biomedical engineering - Abstract
We consider application of optical coherence elastography (OCE) to problems of laser-assisted structural modification/reshaping of avascular collagenous tissues used for fabrication of cartilaginous implants and corneal tissue reshaping for perspective technologies of vision-correction. The developed OCE technique allows one to quantitatively visualize aperiodic strains during the IR-laser irradiation of the tissue samples and evaluate cumulative strains produced by the laser irradiations. OCE can assess stability of laser-modeled implants via monitoring of post-irradiation slow strains and to study the interplay of temperature and thermal stresses to optimize tissue reshaping. Irradiation-induced micro-porosity in the tissue can be assessed via combination of strain mapping with compressional optical elastography.
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- 2020
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10. Extracting shear and normal compliances of crack-like defects from pressure dependences of elastic-wave velocities
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Andrey V. Radostin, Arcady Dyskin, Vladimir Y. Zaitsev, and Elena Pasternak
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Materials science ,010504 meteorology & atmospheric sciences ,business.industry ,Structural engineering ,Mechanics ,Pure shear ,010502 geochemistry & geophysics ,Geotechnical Engineering and Engineering Geology ,Poisson distribution ,01 natural sciences ,Moduli ,symbols.namesake ,Shear (geology) ,symbols ,business ,Porosity ,0105 earth and related environmental sciences - Abstract
We present a differential formulation of effective-medium model in which the normal and shear compliances of the high-compliance porosity are explicitly decoupled. This feature of the decoupled-compliance model (DC model) is in contrast to conventional models in which such defect's properties are implicitly assumed and are subject to strong limitations defined by the used particular crack model. Comparison with the DC model makes it possible to reveal such implicit assumptions in the conventional models. Furthermore, for the conventional cracks, our approach gives the same results as the conventional models. The ability of the DC model to incorporate arbitrary defect properties in terms of their normal-to-shear compliance ratio ( q -ratio) is used to formulate an analogue of Hashin-Shtrikman constraints on the range of feasible crack-induced variations in the moduli. Comparison of the DC model with experimental pressure dependences of elastic-wave velocities in rocks makes it possible to extract the q -ratio for real crack-like defects. These results demonstrate that properties of real cracks usually noticeably differ from those of popular crack models such as cracks with free faces (e.g., penny-shape) or pure shear cracks. We discuss an example of sandstone with pronouncedly negative Poisson's ratio that is due to the fact that the ratio of normal-to-shear compliances of voids in this rock ( q ~7–8) is significantly higher than for the conventional cracks ( q ~2). Ability of the DC model to accurately extrapolate pressure dependences of the moduli from relatively low pressures to several times greater is demonstrated, including the cases, for which the conventional models give huge errors. The introduced parameter q – the ratio of normal-to-shear compliances of voids – provides additional insight into properties of real crack-like defect in rocks.
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- 2017
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11. Optical coherence elastography for strain dynamics measurements in laser correction of cornea shape
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Olga I. Baum, A. V. Bolshunov, Alexander I. Omelchenko, V. I. Siplivy, Alex Vitkin, Emil N. Sobol, Alexander L. Matveyev, Lev A. Matveev, Avetisov Se, Vladimir Y. Zaitsev, Dmitry V. Shabanov, and Grigory V. Gelikonov
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Materials science ,genetic structures ,General Physics and Astronomy ,01 natural sciences ,General Biochemistry, Genetics and Molecular Biology ,law.invention ,Cornea ,010309 optics ,03 medical and health sciences ,0302 clinical medicine ,Optics ,Optical coherence tomography ,law ,0103 physical sciences ,medicine ,General Materials Science ,Transparency (data compression) ,Sparse matrix ,medicine.diagnostic_test ,business.industry ,Scattering ,Lasers ,Temperature ,General Engineering ,General Chemistry ,Laser ,eye diseases ,Visualization ,medicine.anatomical_structure ,Temporal resolution ,030221 ophthalmology & optometry ,Stress, Mechanical ,sense organs ,business ,Tomography, Optical Coherence - Abstract
We describe the use of elastographic processing in phase-sensitive optical coherence tomography (OCT) for visualizing dynamics of strain and tissue-shape changes during laser-induced photothermal corneal reshaping, for applications in the emerging field of non-destructive and non-ablative (non-LASIK) laser vision correction. The proposed phase-processing approach based on fairly sparse data acquisition enabled rapid data processing and near-real-time visualization of dynamic strains. The approach avoids conventional phase unwrapping, yet allows for mapping strains even for significantly supra-wavelength inter-frame displacements of scatterers accompanied by multiple phase-wrapping. These developments bode well for real-time feedback systems for controlling the dynamics of corneal deformation with 10-100 ms temporal resolution, and for suitably long-term monitoring of resultant reshaping of the cornea. In ex-vivo experiments with excised rabbit eyes, we demonstrate temporal plastification of cornea that allows shape changes relevant for vision-correction applications without affecting its transparency. We demonstrate OCT's ability to detect achieving of threshold temperatures required for tissue plastification and simultaneously characterize transient and cumulative strain distributions, surface displacements, and scattering tissue properties. Comparison with previously used methods for studying laser-induced reshaping of cartilaginous tissues and numerical simulations is performed.
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- 2017
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12. Interplay of temperature, thermal‐stresses and strains in laser‐assisted modification of collagenous tissues: Speckle‐contrast and OCT‐based studies
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Emil N. Sobol, Alexander P. Sviridov, Olga I. Baum, Alexander L. Matveyev, Alexander A. Sovetsky, Vladimir Y. Zaitsev, A. V. Yuzhakov, Maria Novikova, and Lev A. Matveev
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Materials science ,General Physics and Astronomy ,01 natural sciences ,General Biochemistry, Genetics and Molecular Biology ,law.invention ,Cornea ,010309 optics ,Speckle pattern ,Optical coherence elastography ,law ,0103 physical sciences ,Thermal ,General Materials Science ,Irradiation ,Lasers ,010401 analytical chemistry ,Far-infrared laser ,Relaxation (NMR) ,Temperature ,General Engineering ,General Chemistry ,Laser ,0104 chemical sciences ,Cartilage ,Elasticity Imaging Techniques ,Monochromatic color ,Biomedical engineering - Abstract
Moderate heating of collagenous tissues such as cartilage and cornea by infrared laser irradiation can produce biologically nondestructive structural rearrangements and relaxation of internal stresses resulting in the tissue reshaping. The reshaping results and eventual changes in optical and biological properties of the tissue strongly depend on the laser-irradiation regime. Here, a speckle-contrast technique based on monochromatic illumination of the tissue in combination with strain mapping by means of optical coherence elastography (OCE) is applied to reveal the interplay between the temperature and thermal stress fields producing tissue modifications. The speckle-based technique ensured en face visualization of cross correlation and contrast of speckle images, with evolving proportions between contributions of temperature increase and thermal-stresses determined by temperature gradients. The speckle-technique findings are corroborated by quantitative OCE-based depth-resolved imaging of irradiation-induced strain-evolution. The revealed relationships can be used for real-time control of the reshaping procedures (e.g., for laser shaping of cartilaginous implants in otolaryngology and maxillofacial surgery) and optimization of the laser-irradiation regimes to ensure the desired reshaping using lower and biologically safer temperatures. The figure of waterfall OCE-image demonstrates how the strain-rate maximum arising in the heating-beam center gradually splits and drifts towards the zones of maximal thermal stresses located at the temperature-profile slopes.
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- 2019
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13. Optical coherence elastography for visualization of spatio-temporal strain dynamics in thermo-mechanical modification of corneal and cartilaginous tissues
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Vladimir Y. Zaitsev, Alexander A. Sovetsky, L. A. Matveev, Olga I. Baum, and Alexander L. Matveyev
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Optical coherence elastography ,Materials science ,Strain (chemistry) ,Dynamics (mechanics) ,Cartilaginous Tissue ,Thermo mechanical ,Visualization ,Biomedical engineering - Published
- 2019
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14. Comparison of elastic properties of tissue samples in various pathological states using optical coherence elastography
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Elena B. Kiseleva, Lydia B. Timofeeva, Dmitriy A. Vorontsov, Lev A. Matveev, Ekaterina V. Gubarkova, Natalia D. Gladkova, Irina A. Kuznetsova, Alexander A. Sovetsky, Alexander L. Matveyev, Alexey Yu. Vorontsov, and Vladimir Y. Zaitsev
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Optical coherence elastography ,Materials science ,Pathological ,Biomedical engineering - Published
- 2019
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15. Phase-sensitive OCT in monitoring of slow-rate strains in laser tissue reshaping
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A. V. Yuzhakov, Lev A. Matveev, A. A. Sovetsky, Aleksand I. Omelchenko, Vladimir Y. Zaitsev, Emil N. Sobol, Grigory V. Gelikonov, Alexander L. Matveyev, and Olga I. Baum
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Materials science ,Phase sensitive ,law ,Spatially resolved ,Slow rate ,Strain estimation ,Inter frame ,Strain mapping ,Laser ,Stability (probability) ,Biomedical engineering ,law.invention - Abstract
We present a realization of real-time OCT-based strain mapping by estimating interframe phase-variation gradient using the developed "vector" method. This technique allows for mapping both fairly fast and large, as well as rather small strains, slowly-varying on intervals ~tens of minutes. Optimization of interframe interval for improving signal-to-noise ratio is discussed and experimentally demonstrated. Ultimate stability of strain estimation with the designed OCT setup is experimentally estimated using stable phantoms. Examples of spatially resolved maps of slowly-varying strains are demonstrated. The developed methods can be used in emerging techniques of laser-assisted modification of collagenous tissues (e.g., for such perspective application as fabrication of cartilaginous implants).
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- 2019
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16. Observation of internal stress relaxation in laser-reshaped cartilaginous implants using OCT-based strain mapping
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Alexander L. Matveyev, Lev A. Matveev, Olga I. Baum, Alexander A. Sovetsky, Vladimir Y. Zaitsev, Yulia M. Alexandrovskaya, and Emil N. Sobol
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Optical coherence elastography ,Materials science ,Nuclear magnetic resonance ,Physics and Astronomy (miscellaneous) ,law ,Relaxation (physics) ,Strain mapping ,Laser ,Instrumentation ,Internal stress ,law.invention - Published
- 2020
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17. Extracting real-crack properties from non-linear elastic behaviour of rocks: abundance of cracks with dominating normal compliance and rocks with negative Poisson ratios
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Elena Pasternak, Andrey V. Radostin, Vladimir Y. Zaitsev, and Arcady Dyskin
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Materials science ,010504 meteorology & atmospheric sciences ,Auxetics ,lcsh:QC801-809 ,Geometry ,Seismic noise ,Dissipation ,010502 geochemistry & geophysics ,Poisson distribution ,01 natural sciences ,Ellipsoid ,Poisson's ratio ,lcsh:QC1-999 ,Nonlinear system ,symbols.namesake ,lcsh:Geophysics. Cosmic physics ,mental disorders ,symbols ,lcsh:Q ,Elasticity (economics) ,lcsh:Science ,lcsh:Physics ,0105 earth and related environmental sciences - Abstract
Results of examination of experimental data on non-linear elasticity of rocks using experimentally determined pressure dependences of P- and S-wave velocities from various literature sources are presented. Overall, over 90 rock samples are considered. Interpretation of the data is performed using an effective-medium description in which cracks are considered as compliant defects with explicitly introduced shear and normal compliances without specifying a particular crack model with an a priori given ratio of the compliances. Comparison with the experimental data indicated abundance (∼ 80 %) of cracks with the normal-to-shear compliance ratios that significantly exceed the values typical of conventionally used crack models (such as penny-shaped cuts or thin ellipsoidal cracks). Correspondingly, rocks with such cracks demonstrate a strongly decreased Poisson ratio including a significant (∼ 45 %) portion of rocks exhibiting negative Poisson ratios at lower pressures, for which the concentration of not yet closed cracks is maximal. The obtained results indicate the necessity for further development of crack models to account for the revealed numerous examples of cracks with strong domination of normal compliance. Discovering such a significant number of naturally auxetic rocks is in contrast to the conventional viewpoint that occurrence of a negative Poisson ratio is an exotic fact that is mostly discussed for artificial structures.
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- 2018
18. Quantitative compressional OCE: obviating pitfalls in using pre-calibrated compliant layers and some other practical obstacles
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Elena V. Zagaynova, Ekaterina V. Gubarkova, Grigory V. Gelikonov, Alexander L. Matveyev, Vladimir Y. Zaitsev, A. A. Sovetsky, Alex Vitkin, Lev A. Matveev, Natalia D. Gladkova, and Marina A. Sirotkina
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Materials science ,medicine.diagnostic_test ,Acoustics ,Stiffness ,Strain mapping ,Young's modulus ,Curvature ,Nonlinear system ,symbols.namesake ,Optical coherence tomography ,Strain distribution ,medicine ,symbols ,Elastography ,medicine.symptom - Abstract
In this report we discuss some practical obstacles/pitfalls arising in realization of quantitative compressional OCE, as well as discuss possible ways of their resolution. More specifically we consider (i) complications in quantification of the Young modulus of tissues related to influence of partial adhesion between the OCT probe and pre-calibrated reference layers - "compliant sensors", (ii) distorting influence of surface curvature/corrugation on strain distribution in the tissue bulk, (iii) ways of enhancement of effective SNR in OCT-based strain mapping without periodic averaging, and (iv) potentially significant influence of nonlinearity of the elastic response of biological tissues on quantification of their stiffness.
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- 2018
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19. Monitoring of slow deformations in laser tissue reshaping with optical coherence elastography
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Vladimir Y. Zaitsev, L. A. Matveev, Aleksander L. Matveev, Dmitry V. Shabanov, Emil N. Sobol, A. A. Sovetsky, A. V. Yuzhakov, Grigory V. Gelikonov, and Olga I. Baum
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Materials science ,medicine.diagnostic_test ,Ir laser ,Strain rate ,Laser ,Signal ,law.invention ,Optical coherence elastography ,medicine.anatomical_structure ,Optical coherence tomography ,law ,Cornea ,medicine ,Elastography ,Biomedical engineering - Abstract
Strain mapping based on analysis of complexvalued signal of optical coherence tomography (OCT) is applied to monitor slow deformations of biological tissues (e.g., cartilage or cornea) subjected to thermo-mechanical reshaping by moderate heating with an IR laser. Insufficiently relaxed internal stresses may slowly distort the required tissue shape on a scale from minutes to hours with strain rate ~10−4 s−1. We show the ability of the developed OCT method to monitor strains with uncertainly ~10−5 on ~102 s intervals sufficient for shape-stability verification in intra-operational preparation of cartilaginous implants.
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- 2018
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20. OCT-based label-free 3D mapping of lymphatic vessels and transparent interstitial-fluid-filled dislocations
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Vladimir Y. Zaitsev, Lev A. Matveev, Valentin Demidov, A. A. Moiseev, Grigory V. Gelikonov, A. A. Sovetsky, A. L. Matveyev, and Alex Vitkin
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Materials science ,genetic structures ,medicine.disease ,eye diseases ,3d mapping ,Lymphatic system ,Oct angiography ,In vivo ,Interstitial fluid ,Pancreatic cancer ,medicine ,sense organs ,Lymph ,Biomedical engineering ,Label free - Abstract
Approach to OCT-lymphangiography (OCT-LA) and interstitial-fluid-filled dislocations mapping that complement speckle variance (SV) OCT angiography is presented. OCT-LA can be extracted from the same OCT raw datasets that were acquired for SV OCT angiography. Lymphatic vessels and interstitial dislocations are filled with transparent fluids (e.g. lymph) and can be separated from the blood vessels and tissue. In vivo application of the OCT-LA approach is demonstrated on NRG mouse with grown BX-PC3 tumor (human pancreatic cancer cells).
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- 2018
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21. Thermo-mechanical mechanism of laser-induced pore-formationin sclera for glaucoma treatment: AFM and OCT investigations
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Emil N. Sobol, A. V. Yuzhakov, Olga I. Baum, Vladimir Y. Zaitsev, Alexander I. Omelchenko, A. A. Sovetsky, and L. A. Matveev
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Intraocular pressure ,Materials science ,genetic structures ,medicine.diagnostic_test ,Glaucoma ,Nanoindentation ,medicine.disease ,Laser ,eye diseases ,Sclera ,law.invention ,medicine.anatomical_structure ,Optical coherence tomography ,law ,Intraocular fluid ,medicine ,sense organs ,Irradiation ,Biomedical engineering - Abstract
A new laser method for increasing uveoscleral outflow path for normalization of intraocular pressure in glaucomatous eyes is presented. Nonuniform laser heating affects the porous system of biological tissues. Formation of new pores in the paralimbal region of the eye can accelerate the flow of the intraocular fluid through the eye sclera and, thus, facilitate normalization of the intraocular pressure. A positive effect of laser impact is achieved, as a rule, in a narrow range of laser radiation parameters, which makes it difficult to choose the intensity and time parameters of laser irradiation due to such factors as nonstationary temperature fields, thermotensions and pressure that can give rise to undesirable effects and complications. The comparison between reflected and transmitted laser light through the eye tissue has allowed to establish the main requirements for laser settings parameters responsible for efficacy and safety of the laser irradiation. The positive effect is achieved only by using relatively small intensity of the laser radiation. At high intensity, the hydraulic permeability decreases due to denaturation and tissue hardening. Atomic Force Microscopy (AFM) measurements with nanoindentation and optical coherence tomography (OCT) based compressional phase-sensitive optical coherence elastography (OCE). OCE measurements demonstrated laser-induced dilatation areas attributed to formation of ensembles of micro-and nano-pores in sclera providing increase in its hydraulic permeability. Much higher resolution AFM examinations directly demonstrated such individual irradiation-produced pores. At the same time, the collagen structure of the sclera is not destroyed, and tissue mechanical properties do not degrade under laser radiation. The process of pore formation is in good agreement with computer simulations of the dynamics of thermal stress fields induced by laser irradiation.
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- 2018
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22. OCT-based characterization of the nonlinear properties of biological tissues in various states
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Alexander L. Matveyev, Natalia D. Gladkova, Ekaterina V. Gubarkova, A. A. Sovetsky, Vladimir Y. Zaitsev, Lev A. Matveev, and Marina A. Sirotkina
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Materials science ,medicine.diagnostic_test ,food and beverages ,Young's modulus ,02 engineering and technology ,Tissue characterization ,021001 nanoscience & nanotechnology ,01 natural sciences ,Viscoelasticity ,Characterization (materials science) ,010309 optics ,Nonlinear system ,symbols.namesake ,Optical coherence tomography ,0103 physical sciences ,medicine ,symbols ,Elastography ,0210 nano-technology ,Biomedical engineering - Abstract
Soft biological tissues manifest strongly pronounced nonlinear elastic behavior. Namely, the Young modulus for some tissues strongly depends on the applied stress. This property can be evaluated by compressional OCT elastography. We demonstrate the evaluation of nonlinear elastic properties on the samples of coronary arteries, breast cancer and cornea. The developed technique can be used for further investigation of the nonlinear properties of healthy and pathological tissues.
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- 2018
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23. Optical coherence elastography assesses tissue modifications in laser reshaping of cornea and cartilages
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A. L. Matveyev, Dmitry V. Shabanov, Alexander I. Omelchenko, Alex Vitkin, Vladimir Y. Zaitsev, Emil N. Sobol, G. V. Gelikonov, A. A. Sovetsky, Olga I. Baum, and L. A. Matveev
- Subjects
Materials science ,medicine.diagnostic_test ,Stiffness ,Laser ,Work related ,law.invention ,Optical coherence elastography ,medicine.anatomical_structure ,Optical coherence tomography ,law ,Cornea ,Microscopy ,medicine ,medicine.symptom ,Tissue stiffness ,Biomedical engineering - Abstract
Non-surgical thermo-mechanical reshaping of avascular collagenous tissues (cartilages and cornea) using moderate heating by IR-laser irradiation is an emerging technology that can find important applications in visioncorrection problems and preparation of cartilaginous implants in otolaryngology. To estimate both transient interframe strains and cumulative resultant strains produced by the laser irradiation of the tissue we use and improved version of strain mapping developed in our previous work related to compressional phase-sensitive optical coherence tomography. To reveal microstructural changes in the tissue regions where irradiation-produced strains do not disappear after temperature equilibration, we apply compressional optical coherence elastography in order to visualize the resultant variations in the tissue stiffness. The so-found regions of the stiffness reduction are attributed to formation of microscopic pores, existence of which agree with independent data obtained using methods of high-resolution microscopy.
- Published
- 2018
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24. Quasistatic in-depth local strain relaxation/creep rate mapping using phase-sensitive optical coherence tomography
- Author
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Vladimir Y. Zaitsev, Alexander L. Matveyev, Aleksandr A. Sovetsky, Dmitry V. Shabanov, Lev A. Matveev, Irina N. Druzhkova, Grigory V. Gelikonov, Dmitry A. Karashtin, Ekaterina V. Gubarkova, Marina A. Sirotkina, Alex Vitkin, Natalia D. Gladkova, Elena V. Zagaynova, and Valentin M. Gelikonov
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Materials science ,genetic structures ,medicine.diagnostic_test ,Strain (chemistry) ,Phase sensitive ,eye diseases ,Viscoelasticity ,Nuclear magnetic resonance ,Optical coherence tomography ,Creep ,Creep rate ,medicine ,Relaxation (physics) ,Composite material ,Quasistatic process - Abstract
OCT-based local strain relaxation/creep evaluation is an emerging tool for tissue viscoelasticity characterization. We present a tool for 2D visualization of local strain relaxation and creep time/rate inside the tissue.
- Published
- 2017
- Full Text
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25. Manifestations of nonlinear elasticity of biological tissues in compressional optical coherence elastography
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Lev A. Matveev, Alex Vitkin, Vladimir Y. Zaitsev, Aleksandr A. Sovetsky, Elena V. Zagaynova, Marina A. Sirotkina, Grigory V. Gelikonov, Alexander L. Matveyev, Natalia D. Gladkova, and Ekaterina V. Gubarkova
- Subjects
Materials science ,medicine.diagnostic_test ,business.industry ,Scattering ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,010309 optics ,Nonlinear system ,Optical coherence elastography ,Optics ,Optical coherence tomography ,0103 physical sciences ,medicine ,Elastography ,Elasticity (economics) ,0210 nano-technology ,Soft layer ,business ,Nonlinear elasticity ,Biomedical engineering - Abstract
We discuss the application of compressional OCT-based elastography for measuring elastic response of biological tissues in the strain range from fractions of one per cent up to strains over ~10% and greater. Such fairly large strains are not typical of phase-sensitive OCT-based elastographic methods and can be measurable due to application of interframe strain-estimation method in which interframe phase gradients are estimated without the necessity of preliminary measuring total displacements of scattering particles in combination with summation of interframe strains. For estimating applied stresses, intervenient soft layer of translucent silicone is used a a reference fairly linear material. The obtained results based on comparison of strains in the reference layer and tissue demonstrate highly nonlinear character of elasticity of biological tissues even for rather moderate strains on order of several per cent.
- Published
- 2017
- Full Text
- View/download PDF
26. Multiparameter thermo-mechanical OCT-based characterization of laser-induced cornea reshaping
- Author
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Alexander A. Sovetsky, Emil N. Sobol, Lev A. Matveev, Alex Vitkin, A. L. Matveyev, Olga I. Baum, Alexander I. Omelchenko, Grigory V. Gelikonov, Dmitry V. Shabanov, and Vladimir Y. Zaitsev
- Subjects
Materials science ,genetic structures ,02 engineering and technology ,01 natural sciences ,law.invention ,010309 optics ,Speckle pattern ,020210 optoelectronics & photonics ,Optics ,Optical coherence tomography ,law ,Cornea ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,medicine ,medicine.diagnostic_test ,business.industry ,Tissue heating ,Laser ,eye diseases ,Characterization (materials science) ,medicine.anatomical_structure ,sense organs ,Elastography ,business ,Thermo mechanical - Abstract
Phase-sensitive optical coherence tomography (OCT) is used for visualizing dynamic and cumulative strains and corneashape changes during laser-produced tissue heating. Such non-destructive (non-ablative) cornea reshaping can be used as a basis of emerging technologies of laser vision correction. In experiments with cartilaginous samples, polyacrilamide phantoms and excised rabbit eyes we demonstrate ability of the developed OCT system to simultaneously characterize transient and cumulated strain distributions, surface displacements, scattering tissue properties and possibility of temperature estimation via thermal-expansion measurements. The proposed approach can be implemented in perspective real-time OCT systems for ensuring safety of new methods of laser reshaping of cornea.
- Published
- 2017
- Full Text
- View/download PDF
27. Optimization of phase-resolved optical coherence elastography for highly-sensitive monitoring of slow-rate strains
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G. V. Gelikonov, Alexander I. Omelchenko, A. V. Yuzhakov, Sergey Yu. Ksenofontov, Olga I. Baum, Lev A. Matveev, Emil N. Sobol, A. L. Matveyev, A. A. Sovetsky, Vladimir Y. Zaitsev, and Dmitry V. Shabanov
- Subjects
Optical coherence elastography ,Optics ,Materials science ,Physics and Astronomy (miscellaneous) ,business.industry ,Slow rate ,Phase (waves) ,Strain mapping ,business ,Instrumentation ,Highly sensitive - Published
- 2019
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28. Strong enhancement of surface diffusion by nonlinear surface acoustic waves
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Anthony J. Manzo, Henry Helvajian, Leonid V. Zhigilei, Vladimir Y. Zaitsev, Chengping Wu, and Maxim V. Shugaev
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Surface diffusion ,Nonlinear acoustics ,Materials science ,Thermal ,Acoustic wave ,Substrate (electronics) ,Diffusion (business) ,Condensed Matter Physics ,Ion acoustic wave ,Molecular physics ,Spectral line ,Electronic, Optical and Magnetic Materials - Abstract
The phenomenon of acoustic activation of surface diffusion is investigated in a combined computational and experimental study. The ability of pulsed laser-generated surface acoustic waves (SAWs) to enhance the mobility of small atomic clusters is demonstrated by directly tracking, with fluorescence microscopy, individual $\mathrm{A}{\mathrm{u}}_{8}$ clusters moving on a (111) silicon substrate. A 19-fold increase in the effective diffusion coefficient is measured in room temperature experiments in the presence of SAWs generated by nanosecond pulse laser irradiation at a 100 Hz repetition rate. A strong enhancement of cluster mobility by SAWs is also observed in large-scale molecular dynamics simulations of surface diffusion of small atomic clusters. The analysis of the computational results demonstrates that the nonlinear sharpening of SAWs and the corresponding enrichment of the SAW spectra by high frequency harmonics which are capable of dynamic coupling to the cluster vibrations are responsible for the efficient acoustic activation of surface mobility in the simulations. The increase in the effective diffusion coefficient is proportional to the number of the SAW pulses passing through the diffusion region per unit time and a dramatic 4500-fold diffusion enhancement (corresponds to an equivalent temperature increase by $\ensuremath{\sim}{10}^{3}\phantom{\rule{0.16em}{0ex}}\mathrm{K}$) is predicted in the simulations for $15\phantom{\rule{0.16em}{0ex}}\mathrm{GHz}$ SAWs. The ability of SAWs to affect atomic-level surface processes has far-reaching implications for the design of new techniques where the acoustic energy serves as an effective substitution for thermal activation in applications where heating must be avoided or rapid switching of surface conditions is required.
- Published
- 2015
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29. Slow Relaxation and Aging Phenomena at the Nanoscale in Granular Materials
- Author
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Patrick Richard, Vladimir Y. Zaitsev, Vitalyi Gusev, Vincent Tournat, Institute of Applied Physics of RAS, Russian Academy of Sciences [Moscow] ( RAS ), Radiosphysics departement, Nizhny Novgorod State University, Laboratoire d'acoustique de l'université du Mans ( LAUM ), Le Mans Université ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Granulats et Procédés d'Elaboration des Matériaux ( IFSTTAR/MAST/GPEM ), Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux ( IFSTTAR ) -PRES Université Nantes Angers Le Mans ( UNAM ), Russian Academy of Sciences [Moscow] (RAS), Laboratoire d'Acoustique de l'Université du Mans (LAUM), Centre National de la Recherche Scientifique (CNRS)-Le Mans Université (UM), Granulats et Procédés d'Elaboration des Matériaux (IFSTTAR/MAST/GPEM), and Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-PRES Université Nantes Angers Le Mans (UNAM)
- Subjects
Materials science ,Bistability ,granular materials ,FOS: Physical sciences ,General Physics and Astronomy ,Thermal fluctuations ,Mechanism based ,Nanotechnology ,02 engineering and technology ,Condensed Matter - Soft Condensed Matter ,Granular material ,01 natural sciences ,Physics - Geophysics ,83.80.Fg, 43.25.+y, 45.70.-n, 83.10.Tv ,Granular matter ,Metastability ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,0103 physical sciences ,010306 general physics ,Nanoscopic scale ,Condensed Matter - Mesoscale and Nanoscale Physics ,nanoscale ,[ PHYS.COND.CM-GEN ] Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other] ,021001 nanoscience & nanotechnology ,Geophysics (physics.geo-ph) ,Chemical physics ,[PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other] ,slow relaxation ,Soft Condensed Matter (cond-mat.soft) ,Relaxation (physics) ,0210 nano-technology - Abstract
Complex systems having metastable elements often demonstrate nearly log-time relaxations and a kind of aging: repeated stimuli weaken the system's relaxational response. Granular matter is known to exhibit a wealth of such behaviors, for which the role of thermal fluctuations is usually ignored. However, we demonstrate that the latter can pronouncedly affect contacting mesoscopic-scale asperities and be macroscopically observed via appropriate acoustic effects. We also propose a mechanism comprising slow relaxations and aging as intrinsic properties of a wide class of systems with metastable states., Comment: 5 pages, 4 figures
- Published
- 2014
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30. To the problem of stiffness-contrast quantification in the correlation-stability approach to OCT elastography
- Author
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Vladimir Y. Zaitsev, Lev A. Matveev, A. L. Matveyev, Valentin M. Gelikonov, and Grigory V. Gelikonov
- Subjects
Digital image correlation ,Materials science ,genetic structures ,medicine.diagnostic_test ,business.industry ,Stiffness ,Image processing ,eye diseases ,Visualization ,Speckle pattern ,Optical coherence tomography ,medicine ,Computer vision ,Elastography ,Artificial intelligence ,medicine.symptom ,Elasticity (economics) ,business ,Biomedical engineering - Abstract
In the initial variant, the recently proposed correlation-stability approach to elasticity mapping in optical coherence tomography (OCT) of tissues was intended for qualitative visualization of the relative stiffness of different regions in tissue. Further development of this approach is aimed at obtaining the stiffness ratio between different tissue regions. In the proposed modified variant, the correlation-stability approach has much in common with the speckle variance approach which is used for visualizing blood microcirculation in OCT. We present preliminary demonstrations of implementation of the modified correlation-stability approach to quantify the relative stiffness using processing of the speckle-structure variability of OCT images of deformed tissues.
- Published
- 2014
- Full Text
- View/download PDF
31. Identification of avalanche precursors by acoustic probing in the bulk of tilted granular layers
- Author
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Vladimir Y. Zaitsev, Patrick Richard, Vincent Tournat, Renaud Delannay, Mickaël Duranteau, Institut de Physique de Rennes ( IPR ), Université de Rennes 1 ( UR1 ), Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire d'acoustique de l'université du Mans ( LAUM ), Le Mans Université ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Institute of Applied Physics of RAS, Russian Academy of Sciences [Moscow] ( RAS ), This work is supported by ANR 2010-BLAN-0927-01 grant 'STABINGRAM' (for STABility loss IN GRAnu-lar Media)., Institut de Physique de Rennes (IPR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Acoustique de l'Université du Mans (LAUM), Le Mans Université (UM)-Centre National de la Recherche Scientifique (CNRS), Russian Academy of Sciences [Moscow] (RAS), and Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
Surface (mathematics) ,granular flow ,Materials science ,[SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] ,granular materials ,Dispersity ,Analytical chemistry ,[PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph] ,02 engineering and technology ,Granular material ,01 natural sciences ,[ SDU.STU.GP ] Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] ,[ PHYS.PHYS.PHYS-GEO-PH ] Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph] ,07.64.+z, 45.70.Ht, 45.70.Mg ,0103 physical sciences ,acoustic measurement ,010306 general physics ,Millisecond ,stability ,021001 nanoscience & nanotechnology ,Condensed Matter::Soft Condensed Matter ,Nonlinear system ,Chemical physics ,Free surface ,0210 nano-technology ,Constant angular velocity ,Event (particle physics) - Abstract
International audience; Understanding the precursors of granular avalanches is important for the prediction of critical events. As part of the dynamics leading to the avalanche, precursors are identified as collective motions of grains on the free surface. When a granular pile is tilted at a constant angular velocity, precursors appear quasi-periodically. In this paper we simultaneously caracterize precursors on the free surface with an optical method and in the bulk with acoustic methods (nonlinear and linear). Surprisingly, the use on nonlinear acoustic method is not necessary to probe rearrangements in the bulk of the granular material. A linear method can also be used provided that the frequency region is the one where the acoustic propagation is sensitive to the solid skeleton formed by the bead-contact network. Our experiments conducted with monodisperse glass beads show that their surface features are by far the most important for the precursor propreties. Our results allow to probe with a few millisecond time resolution (less than 10−2 degree of inclination) the relaxation phenomena associated to each precursor event. Interpretations of different precursors and different experiments provide an interesting train of thought for the understanding of destabilization mechanisms in granular systems.
- Published
- 2013
- Full Text
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32. Correlation-stability approach in optical microelastography of tissues
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Grigory V. Gelikonov, Vladimir Y. Zaitsev, A. L. Matveyev, Lev A. Matveev, and Valentin M. Gelikonov
- Subjects
Correlation ,Digital image correlation ,Rigidity (electromagnetism) ,Materials science ,Optics ,Optical coherence tomography ,medicine.diagnostic_test ,business.industry ,medicine ,Geometry ,Image processing ,Elastography ,business - Abstract
In the conventional cross-correlation approach to reconstruction of displacements (and then the strain field), the reduction of correlation between the consequently obtained images caused by distortions of scatterer patterns in deformed tissues is a negative factor reducing the accuracy of the displacement-field reconstruction. However, just this reduction in the cross-correlation between the images of deformed tissues can be intentionally used for evaluation of the tissue rigidity. Evidently, in areas with higher rigidity the distortions of the scatterer pattern in deformed tissues are smaller and, correspondingly, the reduction in the cross-correlation between the consequent OCT images is also smaller. Observation of such a cross-correlation field we call the correlation-stability approach (CS-approach) to mapping the relative rigidity of biological tissues. The proposed CS-approach is illustrated by numerical simulations corresponding to two characteristic cases (sheared or compressed samples with average strain range 25 - 100 %). This strain level is favorable for performing such mapping "by hand" and in vivo conditions. Some examples of such in vivo obtained relative-rigidity images are presented in this report.
- Published
- 2013
- Full Text
- View/download PDF
33. Optical coherence tomography for visualizing transient strains and measuring large deformations in laser-induced tissue reshaping
- Author
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Vladimir Y. Zaitsev, Alexander L. Matveyev, Alexander I. Omelchenko, Dmitry V. Shabanov, V. M. Svistushkin, Emil N. Sobol, Olga I. Baum, Grigory V. Gelikonov, and Lev A. Matveev
- Subjects
Materials science ,genetic structures ,Physics and Astronomy (miscellaneous) ,Context (language use) ,02 engineering and technology ,01 natural sciences ,law.invention ,010309 optics ,Speckle pattern ,020210 optoelectronics & photonics ,Optics ,Optical coherence tomography ,law ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,medicine ,Instrumentation ,medicine.diagnostic_test ,business.industry ,Strain mapping ,Laser ,Phase unwrapping ,eye diseases ,sense organs ,Transient (oscillation) ,business - Abstract
In the context of the development of emerging laser-assisted thermo-mechanical technologies for non-destructive reshaping of avascular collagenous tissues (cartilages and cornea), we report the first application of phase-sensitive optical coherence tomography (OCT) for visualizing transient strains involving supra-wavelength inter-frame displacements of scatterers. Usually phase-sensitive OCT assumes the visualization of sub-pixel and even sub-wavelength displacements of scatterers and fairly small strains (say
- Published
- 2016
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- View/download PDF
34. Probing Granular Media via Nonlinear Acoustic Effects
- Author
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Bernard Castagnède, Vladimir Y. Zaitsev, V. E. Nazarov, Vincent Tournat, and Vitalyi Gusev
- Subjects
Physical acoustics ,Shear waves ,symbols.namesake ,Materials science ,Nonlinear acoustics ,Acoustics ,symbols ,Acoustic wave equation ,Acoustic wave ,Mechanics ,Rayleigh wave ,Ion acoustic wave ,Granular material - Abstract
Probing of a granular medium by a parametric nonlinear emitting antenna is reported. Shear waves are used for this purpose for the first time. Strong anisotropy of nonlinearity for shear waves with different polarizations is observed. Excitation of longitudinal acoustic wave at the second harmonic by sinusoidal shear acoustic wave and subharmonics generation caused by propagation of the acoustic wave have been observed. The ensemble of the experiments confirms that the nonlinear interactions of acoustic waves in granular assemblages are highly sensitive to the fraction of weakly loaded (and weakly “unloaded”) contacts. Evidence is given that a significant portion of weak contact forces is localized below 0.01 of the mean force — a range previously inaccessible by any other techniques.
- Published
- 2005
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- View/download PDF
35. Anomalous nonlinearity of microstructured solids: From diverse manifestations to common roots
- Author
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I. Belyaeva and Vladimir Y. Zaitsev
- Subjects
Nonlinear system ,Materials science ,Nonlinear acoustics ,Acoustic wave absorption ,Linear elasticity ,Mineralogy ,Composite material ,Microstructure ,Granular material ,Crystallographic defect - Abstract
The report presents an instructive physical model applicable to a wide class of microinhomogeneous solids (e.g., rocks, grainy materials, concretes, damaged metals, etc.). It follows readily from the suggested model that the microinhomogeneities can insignificantly influence linear elasticity, whereas a sharp increase of the elastic nonlinearity and the occurrence of a frequency-independent Q-factor appear to be complementary manifestations of the same microstructure.
- Published
- 2000
- Full Text
- View/download PDF
36. Nonlinear Vibro-Acoustic Response of a Metal Sample With a Discontinuity-Like Defect As Related to Damage Detection Problems
- Author
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Paul Sas and Vladimir Y. Zaitsev
- Subjects
Vibration ,Damage detection ,Nonlinear system ,Materials science ,Discontinuity (geotechnical engineering) ,business.industry ,Acoustics ,Structural engineering ,business ,Structural acoustics ,Sample (graphics) ,Acoustic response - Abstract
The nonlinear vibro-acoustic response of solid samples containing quite a small amount of defects can be anomalously high in magnitude compared to the case of undamaged intact solids. Functional dependencies of the nonlinear effects exhibit rather interesting behavior. In this paper, experimental results on nonlinearity-induced cross-modulation of a high-frequency (HF) f = 15...30 kHz signal by a low-frequency (LF) F = 20–60 Hz vibration in an aluminium plate with a small single crack are reported. Comparison with a reference sample (the identical plate without a crack) has proven that the presence of such a small defect can be easily detected due to its nonlinear manifestations. It is demonstrated that under proper choice of the sounding signal parameters, the effect level can be so pronounced that the amplitude of the modulation side-lobes originated due to the nonlinearity exceeds the amplitude of the fundamental harmonic of the HF signal. Main physical features of the observed phenomena are pointed out, their physical explanation is suggested and some simulation results are also presented.
- Published
- 1999
- Full Text
- View/download PDF
37. Linear mode coupling and polarization statistics of coherent light in twisted single-mode fibers with random inhomogeneities
- Author
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Vladimir Y. Zaitsev, Vl. V. Kocharovsky, Vitaly V. Kocharovsky, and Yu. M. Mironov
- Subjects
Optics ,Birefringence ,Materials science ,Polarization mode dispersion ,business.industry ,Optical engineering ,Mode coupling ,Broadband ,Single-mode optical fiber ,Physics::Optics ,business ,Polarization (waves) ,Linear coupling - Abstract
Linear coupling of helical optical modes in twisted and birefringent inhomogeneous fibers is rigorously incorporated to the newly derived polarization transfer equations, and statistical polarization parameters of partially coherent light emitted by a broadband source and transmitted through a dispersive single-mode fiber with random inhomogeneities are calculated analytically in the limiting case of slow cross talk between helical modes.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
- Published
- 1997
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38. [Untitled]
- Author
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Vladimir Y. Zaitsev, Veniamin E. Nazarov, and Vladimir I Talanov
- Subjects
Materials science ,General Physics and Astronomy ,Microstructure ,Engineering physics - Published
- 2006
- Full Text
- View/download PDF
39. Comparison of linear and nonlinear elastic moduli for rocks by use of a granular medium model
- Author
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Irina Yu. Belyaeva, Vladimir Y. Zaitsev, Alexander Sutin, and Lev A. Ostrovsky
- Subjects
Stress (mechanics) ,Nonlinear system ,Nonlinear acoustics ,Materials science ,Acoustics and Ultrasonics ,Arts and Humanities (miscellaneous) ,Mathematical model ,Structure (category theory) ,Mechanics ,Granular material ,Elastic modulus ,Moduli - Abstract
Comparative analysis of linear and nonlinear elastic parameters variability depending on material structure and initial stress is given based on the model of the medium as of a granular structure with fluid pore filling. Examples of such variations for some geological conditions presumably interesting for seismoprospecting, are presented. It is demonstrated that the nonlinearity parameter may be used in exploration seismology as a characteristic much more sensitive to the changes of the medium structure than conventially measured linear moduli.
- Published
- 1994
- Full Text
- View/download PDF
40. Thermoelastic mechanism for logarithmic slow dynamics and memory in elastic wave interactions with individual cracks
- Author
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Bernard Castagnède, Vitalyi Gusev, and Vladimir Y. Zaitsev
- Subjects
Condensed Matter::Materials Science ,Materials science ,Thermoelastic damping ,Nonlinear acoustics ,Logarithm ,Hardening (metallurgy) ,General Physics and Astronomy ,Nonlinear perturbations ,Acoustic wave ,Mechanics ,Softening - Abstract
Logarithmic-in-time slow dynamics has been found for individual cracks in a solid. Furthermore, this phenomenon is observed during both the crack acoustic conditioning and the subsequent relaxation. A thermoelastic mechanism is suggested which relates the log-time behavior to the essentially 2D character of the heating and cooling of the crack perimeter and inner contacts. Nonlinear perturbation of the contacts by a stronger (pump) wave causes either softening or hardening of the sample, and induces either additional absorption or transparency for a weaker (probe) acoustic wave depending on frequency of the latter.
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