Detailed study of the luminescence of multiple brown CVD diamonds was performed. It has been found that the well-known optical center with zero-phonon line at 468 nm is a characteristic of brown ...color. It has been found that the defects responsible for 468 nm center are located within brown striations suggesting close relation of the 468 nm center and the vacancy clusters. Simultaneous reduction of the intensity of 468 nm center and brown color during annealing support the assumption of their close relation. Identical spectroscopic parameters of the 468 nm center and the radiation center with ZPL at 492 nm suggest that the former relates to an intrinsic defect probably containing vacancies. The distribution of intensity of the 468 nm center in some brown diamonds follows the distribution of the NV− center while being opposite to that of the NV0 center and the dislocation-related A-band. This observation suggests the negative charge state of the 468 nm center. Due to its high luminescence efficiency, the 468 nm center can be used as a highly sensitive indicator of the traces of vacancy clusters. We found that the 468 nm center is detected practically in every as-grown CVD diamond including colorless CVD diamonds of high structural perfection and high purity.
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•468 nm center is the luminescence signature of brown CVD diamonds.•468 nm center is assigned to negatively-charged intrinsic defects located at vacancy clusters in CVD diamonds.•468 nm luminescence can be used for detection of trace concentrations of vacancy clusters in CVD diamonds.
We present a non-invasive (albeit contact) method based on Optical Coherence Elastography (OCE) enabling the in vivo segmentation of morphological tissue constituents, in particular, monitoring of ...morphological alterations during both tumor development and its response to therapies. The method uses compressional OCE to reconstruct tissue stiffness map as the first step. Then the OCE-image is divided into regions, for which the Young's modulus (stiffness) falls in specific ranges corresponding to the morphological constituents to be discriminated. These stiffness ranges (characteristic "stiffness spectra") are initially determined by careful comparison of the "gold-standard" histological data and the OCE-based stiffness map for the corresponding tissue regions. After such pre-calibration, the results of morphological segmentation of OCE-images demonstrate a striking similarity with the histological results in terms of percentage of the segmented zones. To validate the sensitivity of the OCE-method and demonstrate its high correlation with conventional histological segmentation we present results obtained in vivo on a murine model of breast cancer in comparative experimental study of the efficacy of two antitumor chemotherapeutic drugs with different mechanisms of action. The new technique allowed in vivo monitoring and quantitative segmentation of (1) viable, (2) dystrophic, (3) necrotic tumor cells and (4) edema zones very similar to morphological segmentation of histological images. Numerous applications in other experimental/clinical areas requiring rapid, nearly real-time, quantitative assessment of tissue structure can be foreseen.
The present work is aimed at supplementing the authors’ paper (2018). Our results on the approximation of distributions of sums of independent summands by the accompanying compound Poisson laws and ...the estimates of the proximity of sequential convolutions of multidimensional distributions on convex polyhedra are shown to be applicable almost automatically to the infinite-dimensional case.
The severe COVID-19 pandemic drives the research toward the SARS-CoV-2 virion structure and the possible therapies against it. Here, we characterized the β-propiolactone inactivated SARS-CoV-2 ...virions using transmission electron microscopy (TEM) and atomic force microscopy (AFM). We compared the SARS-CoV-2 samples purified by two consecutive chromatographic procedures (size exclusion chromatography SEC, followed by ion-exchange chromatography IEC) with samples purified by ultracentrifugation. The samples prepared using SEC and IEC retained more spikes on the surface than the ones prepared using ultracentrifugation, as confirmed by TEM and AFM. TEM showed that the spike (S) proteins were in the pre-fusion conformation. Notably, the S proteins could be recognized by specific monoclonal antibodies. Analytical TEM showed that the inactivated virions retained nucleic acid. Altogether, we demonstrated that the inactivated SARS-CoV-2 virions retain the structural features of native viruses and provide a prospective vaccine candidate.
For the most popular method of scan formation in Optical Coherence Tomography (OCT) based on plane-parallel scanning of the illuminating beam, we present a compact but rigorous K-space description in ...which the spectral representation is used to describe both the axial and lateral structure of the illuminating/received OCT signals. Along with the majority of descriptions of OCT-image formation, the discussed approach relies on the basic principle of OCT operation, in which ballistic backscattering of the illuminating light is assumed. This single-scattering assumption is the main limitation, whereas in other aspects, the presented approach is rather general. In particular, it is applicable to arbitrary beam shapes without the need for paraxial approximation or the assumption of Gaussian beams. The main result of this study is the use of the proposed K-space description to analytically derive a filtering function that allows one to digitally transform the initial 3D set of complex-valued OCT data into a desired (target) dataset of a rather general form. An essential feature of the proposed filtering procedures is the utilization of both phase and amplitude transformations, unlike conventionally discussed phase-only transformations. To illustrate the efficiency and generality of the proposed filtering function, the latter is applied to the mutual transformation of non-Gaussian beams and to the digital elimination of arbitrary aberrations at the illuminating/receiving aperture. As another example, in addition to the conventionally discussed digital refocusing enabling depth-independent lateral resolution the same as in the physical focus, we use the derived filtering function to perform digital "super-refocusing." The latter does not yet overcome the diffraction limit but readily enables lateral resolution several times better than in the initial physical focus.
Application of optical coherence tomography (OCT) in neurosurgery mostly includes the discrimination between intact and malignant tissues aimed at the detection of brain tumor margins. For particular ...tissue types, the existing approaches demonstrate low performance, which stimulates the further research for their improvement. The analysis of speckle patterns of brain OCT images is proposed to be taken into account for the discrimination between human brain glioma tissue and intact cortex and white matter. The speckle properties provide additional information of tissue structure, which could help to increase the efficiency of tissue differentiation. The wavelet analysis of OCT speckle patterns was applied to extract the power of local brightness fluctuations in speckle and its standard deviation. The speckle properties are analysed together with attenuation ones using a set of ex vivo brain tissue samples, including glioma of different grades. Various combinations of these features are considered to perform linear discriminant analysis for tissue differentiation. The results reveal that it is reasonable to include the local brightness fluctuations at first two wavelet decomposition levels in the analysis of OCT brain images aimed at neurosurgical diagnosis.
Kinetics of WC coarsening during sintering of WC-10 wt% Co cemented carbide grades was examined by use of submicron WC powders with a broad grain size distribution containing much nanograin fraction, ...medium-fine-grain powders with a narrow grain size distribution containing little nanograin fraction and medium-grain powders with a very narrow grain size distribution not containing nanograin fraction. Based on the kinetic curves re-constructed in the Arrhenius coordinates, values of the apparent activation energy for each carbide grade were obtained, which allowed the limiting stage of the WC coarsening process to be evaluated. The limiting stage of the WC coarsening process for the medium-grain grade is related to the diffusion of W and C atoms in the liquid binder during sintering. For the submicron grade the limiting stage of the WC coarsening process is related to interfacial reactions at WC/liquid interfaces. In this case, the diffusion of W and C atoms dissolved in the liquid binder is fast due to a very significant difference between sizes of the fine/nano WC grains and coarser WC grains. When increasing the sintering temperature and time above a certain level, the significant acceleration of WC coarsening takes place indicating the transition of the process to the stage of anomalous grain growth, at which the formation of abnormally large WC grains in the microstructure determines the whole WC coarsening process. The limiting stage of the WC coarsening process for the medium-fine-grain grade is mainly related to diffusion of W and C atoms dissolved in the liquid binder.
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•WC coarsening during sintering of cemented carbide grades of three types was examined.•Activation energies of WC grain growth for each type of carbide grade were obtained.•Diffusion of W and C in liquid Co is limiting stage of WC coarsening for medium-fine grade.•Diffusion of W and C in liquid is also limiting stage of WC coarsening for medium-grain grade.•Reactions at WC/liquid interfaces are limiting stages of WC coarsening for submicron grade.
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•The temperature difference is 40°C.•The heat exchange with atmosphere is found to contribute to the temperature field.•Increase of the evaporative mass flux near the contact line.•At ...the final stage of the drop life the specific evaporation rate abruptly increases.•The specific evaporation rate is inversely proportional to the contact radius.
This paper presents an experimental and theoretical study of the evaporation of a sessile water drop to open atmosphere when the temperature difference between the solid substrate and the atmosphere is about 40°C. Using substrates with different wettability we investigate all three modes of droplet evaporation: pinning, partial pinning and depinning. One of the most important results is that at the final stage of the drop life the specific evaporation rate abruptly increases especially for drops with small and moderate contact angle hysteresis. The coupled heat and mass transfer model is considered where the temperature field on the drop surface determines the distribution of vapor concentration on liquid–gas interface. The heat exchange of liquid drop with gas phase strongly affects the temperature distribution on the droplet surface. There is an appreciable increase of temperature close to periphery of the droplet near the contact line. And this leads to increasing of evaporative mass flux near the contact line. We calculate the evaporation rate and conclude that the global evaporation rate is proportional to the contact radius rb while the drop area is proportional to the drop contact radius squared rb2. Thus, the specific evaporation rate (evaporation rate per drop area) is a function of 1/rb and diverges at the end of the evaporation when the drop contact radius tends to zero. The calculated specific evaporation rate is in excellent agreement with the experimental data.
•Behavioral patterns in rats were evaluated using the lithium-pilocarpine model.•Motor activity is increased during both latent and chronic phases of the model.•Spatial and fear-associated memory ...disturbances are observed.•Rats exhibit decreased anxiety and no changes in depressive-like behavior.•Epileptic rats exhibit disturbed communicative behavior.
The aim of this study was to evaluate in detail behavioral patterns and comorbid disturbances in rats using the lithium-pilocarpine model. A comprehensive set of behavioral tests was used to investigate behavioral patterns, including the open field test, Morris water maze, Y-maze, fear conditioning, the elevated plus maze, the forced swimming test, and the resident-intruder paradigm. Motor and explorative activity, learning and memory, anxiety and depressive-like behavior, aggression, and communication were evaluated 8–15 d after pilocarpine-induced status epilepticus (SE) (latent phase of the model) and 41–53 d (chronic phase) after pilocarpine-induced SE. Increased motor activity and impaired memory function were the most noticeable behavioral modifications in the epileptic rats. Both the movement speed and distance traveled increased in the open field test in both the latent and chronic phases. Significant impairments were detected in short-and long-term spatial memory in the Morris water maze during the latent phase. Besides the alterations in spatial memory, behaviors indicative of short- and long-term fear-associated memory disturbances were observed in the fear conditioning test during the chronic phase of the model. In the resident-intruder paradigm, epileptic rats exhibited disturbed communicative behavior, with impaired social behaviors. In contrast, emotional disturbances were less prominent, with the rats exhibiting decreased anxiety. There were no changes in depressive-like behavior. The data suggest that the lithium-pilocarpine model of TLE in rodents is more useful for studies of comorbid disturbances in memory, hyperactivity, and social behavior than for research on psychoemotional impairments, such as anxiety and depression.
The transcriptional regulatory machinery in mitochondrial bioenergetics is complex and is still not completely understood. We previously demonstrated that the histone methyltransferase Smyd1 ...regulates mitochondrial energetics. Here, we identified Perm1 (PPARGC-1 and ESRR-induced regulator, muscle specific 1) as a downstream target of Smyd1 through RNA-seq. Chromatin immunoprecipitation assay showed that Smyd1 directly interacts with the promoter of Perm1 in the mouse heart, and this interaction was significantly reduced in mouse hearts failing due to pressure overload for 4 weeks, where Perm1 was downregulated (24.4 ± 5.9% of sham, p<0.05). Similarly, the Perm1 protein level was significantly decreased in patients with advanced heart failure (55.2 ± 13.1% of donors, p<0.05). Phenylephrine (PE)-induced hypertrophic stress in cardiomyocytes also led to downregulation of Perm1 (55.7 ± 5.7% of control, p<0.05), and adenovirus-mediated overexpression of Perm1 rescued PE-induced downregulation of estrogen-related receptor alpha (ERRα), a key transcriptional regulator of mitochondrial energetics, and its target gene, Ndufv1 (Complex I). Pathway enrichment analysis of cardiomyocytes in which Perm1 was knocked-down by siRNA (siPerm1), revealed that the most downregulated pathway was metabolism. Cell stress tests using the Seahorse XF analyzer showed that basal respiration and ATP production were significantly reduced in siPerm1 cardiomyocytes (40.7% and 23.6% of scrambled-siRNA, respectively, both p<0.05). Luciferase reporter gene assay further revealed that Perm1 dose-dependently increased the promoter activity of the ERRα gene and known target of ERRα, Ndufv1 (Complex I). Overall, our study demonstrates that Perm1 is an essential regulator of cardiac energetics through ERRα, as part of the Smyd1 regulatory network.
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