The regularities of deformation and fracture of sandstone under nonproportional biaxial and triaxial cyclic compression accompanied by the rotation of the Lamé ellipsoid and in situ continuous ...detection of acoustic emission are investigated experimentally on the “Triaxial Independent Loading Test System” at the Ishlinskii Institute for Problems in Mechanics, Russian Academy of Sciences. It is found that the manifestation of the Kaiser effect in the current cycle of multiaxial nonproportional compression depends on the behavior of the size, shape, and orientation of the Lamé ellipsoid with respect to the previous cycle. The Kaiser effect is observed in the case when the material has already been subjected to active loading corresponding to the set orientation of the stress ellipsoid. The degree of the specified-effect manifestation is determined by the behavior of the shape of the Lamé ellipsoid.
The changes in the substituted La0.5Sr0.5FeO3−γ orthoferrite under vacuum annealing in the temperature range of 200–650 °C have been studied by X-ray diffraction analysis, as well as Mössbauer and ...Raman spectroscopy. Annealing of the as–prepared ferrite with the rhombohedral structure (R3‾c) resulted in its transition to the cubic one (Pm3‾m) at 650 °C. In the as–prepared ferrite being paramagnetic at room temperature, Fe ions were detected in an averaged–valence state between Fe3+ and Fe4+, which was not revealed with a decrease in the temperature down to 85 K. Gradual oxygen loss and an increase in the number of oxygen vacancies took place with an increase in the vacuum annealing temperature. Only Fe3+ ions were present in the ferrite at a vacuum annealing temperature above 500 °C. Several Zeeman sextets in the Mössbauer spectra associated with Fe3+ ions were resulted from the presence of oxygen vacancies and Fe4+ ions in the local environment of Fe3+ ions. The variations in the ratio of the valence states of Fe ions obtained from Mössbauer data depending on a vacuum annealing temperature allowed determining the content of oxygen in all the investigated samples. The contribution of Fe3+ ions that did not have Fe4+ ions and oxygen vacancies in their local environment was shown to increase with a vacuum annealing temperature from 12% (for the as–prepared sample) to 60% (for the sample annealed at 650 °C). On a whole, the process taking place under vacuum annealing can be characterized as a variation of the local environment of Fe3+ ions towards a decrease in its distortion. It was found that the width of the peaks of the Raman spectra decreased and their amplitude increased with an increase in the vacuum annealing temperature, which also demonstrated the improvement of the structural perfection of the samples.
This paper presents the results of analysis of the chemical composition of molasses obtained in the conditions of agricultural organizations from locally produced grain. The research was carried out ...on wheat and barley taken from one of the farms in Russia. The prepared grain molasses is a homogeneous mass. In the finished product, moisture, energy feed unit, exchange energy, crude and digestible protein, crude fiber, sugar, and starch were determined by standard methods. The chemical composition in the finished grain product was determined at natural moisture and air-dry condition. Grain syrup obtained from wheat contains exchangeable energy of 9.56 MJ, crude protein 12.57 %, digestible protein 93.0.0 gkg−1 and crude fiber 2.33 %. In addition, 1 kg of the product contains 299.0 and 133.0 g, respectively, of sugar and starch. The finished product obtained from barley contains 73.6 % moisture, 2.48 MJ of exchangeable energy, 30.3 and 22.7 gkg−1 of raw and digestible protein, respectively, 1.37 % of fiber, 69.3 and 46.7 g sugar and fiber, respectively. Thus, according to the results of the material obtained, it was concluded that it is possible to prepare grain feed syrup under the conditions of a farm from local grain raw materials, in particular from barley and wheat.
Children are more likely to develop epileptic seizures (ictal discharges lasting tens of seconds) than adults. A higher predisposition of the juvenile brain to the generation of epileptiform activity ...is thought to be due to a prevalence of inhibition over excitation at the early stage of brain development. However, the molecular and physiological mechanisms underlying these age-related differences are yet to be clarified. We compared the ictal activity induced by a convulsant 4-aminopyridine (4-AP) in the horizontal slices of the entorhinal cortex and hippocampus of 3- and 8-week-old Wistar rats. In 3-week-old rats, the ictal discharge was always preceded by a detectable preictal activity, as manifested in one or several 3–4-s GABA-glutamate events, whereas in 8-week-old rats, such events were typically absent or very rare (no more than one occasional short event). The ictal activity resistance to external exposures was also age-dependent. In 8-week-old rats, by contrast to 3-week-old animals, ictal discharge generation in the entorhinal cortex was blocked completely and replaced by 0.2–0.3 Hz interictal activity (simultaneous 1–3-s burst discharges) by a partial blockade of KCC2 cotransporter or Na
+
–K
+
-pump, as well as by low-frequency electric stimulation. Thus, our data indicate that ictal discharges in the immature (3-week-old) brain are more resistant to external exposures than in the brain of adult rats. Interictal and ictal epileptiform activities are antagonistic in 8-week-old animals. In contrast, the appearance of interictal activity interrupts the generation of ictal discharges completely. It can therefore be considered as one of the putative antiepileptic mechanisms in the mature rat brain.
Abstract We report a new application of compression optical coherence elastography (C‐OCE) to monitor the emergence of ruptures in individual layers of longitudinally stretched small‐intestine walls ...using tissue samples ( n = 36) from nine minipigs. Before stretching, C‐OCE successfully estimated stiffness for each intestine‐wall layer: longitudinal muscular layer with serosa, circumferential muscular layer, submucosa and mucosa. In stretched samples, C‐OCE clearly visualized initial stiffening in both muscular layers. By 25% elongation, a sharp stiffness decrease for the longitudinal muscular layer, indicated emergence of tears in all samples. With further stretching, for most samples, ruptures emerged in the circumferential muscular layer and submucosa, while mucosa remained undamaged. Histology confirmed the OCE‐revealed damaging and absence of tissue damage for ~15% elongation. Thus, C‐OCE has demonstrated a high potential for determining the safety tissue‐stretching threshold which afterward may be used intraoperatively to prevent rupture risk in intestinal tissues stretched during various diagnostic/therapeutic procedures.
The possibility to assess molecular-biological and morphological features of particular breast cancer types can improve the precision of resection margin detection and enable accurate determining of ...the tumor aggressiveness, which is important for treatment selection. To enable reliable differentiation of breast-cancer subtypes and evaluation of resection margin, without performing conventional histological procedures, here we apply cross-polarization optical coherence tomography (CP-OCT) and compare it with a novel variant of compressional optical coherence elastography (C-OCE) in terms of the diagnostic accuracy (Ac) with histological verification. The study used 70 excised breast cancer specimens with different morphological structure and molecular status (Luminal A, Luminal B, Her2/Neo+, non-luminal and triple-negative cancer). Our first aim was to formulate convenient criteria of visual assessment of CP-OCT and C-OCE images intended (i) to differentiate tumorous and non-tumorous tissues and (ii) to enable more precise differentiation among different malignant states. We identified such criteria based on the presence of heterogeneities and characteristics of signal attenuation in CP-OCT images, as well as the presence of inclusions/mosaic structures combined with visually feasible assessment of several stiffness grades in C-OCE images. Secondly, we performed a blinded reader study of the Ac of C-OCE versus CP-OCT, for delineation of tumorous versus non-tumorous tissues followed by identification of breast cancer subtypes. For tumor detection, C-OCE showed higher specificity than CP-OCT (97.5% versus 93.3%) and higher Ac (96.0 versus 92.4%). For the first time, the Ac of C-OCE and CP-OCT were evaluated for differentiation between non-invasive and invasive breast cancer (90.4% and 82.5%, respectively). Furthermore, for invasive cancers, the difference between invasive but low-aggressive and highly-aggressive subtypes can be detected. For differentiation between non-tumorous tissue and low-aggressive breast-cancer subtypes, Ac was 95.7% for C-OCE and 88.1% for CP-OCT. For differentiation between non-tumorous tissue and highly-aggressive breast cancers, Ac was found to be 98.3% for C-OCE and 97.2% for CP-OCT. In all cases C-OCE showed better diagnostic parameters independently of the tumor type. These findings confirm the high potential of OCT-based examinations for rapid and accurate diagnostics during breast conservation surgery.
Quantification of the immunoreactive fraction (IRF) of radioactive isotope-labeled antibodies or their fragments is necessary to assess the specific activity of radiopharmaceuticals. Traditionally, ...cells expressing the target molecules on their surface are used to determine IRF, but such analysis is time-consuming and has difficulties with standardization. The aim of the study was to develop a fast and reliable method for quantitative determination of IRF by 68Ga-labeled VHH antibodies to PD-L1 based on the use of magnetic particles coated with antigen molecules.Materials and MethodsCommercially available magnetic particles coated with protein A have been used in our study. The antigen conjugated with the Fc fragment (PD-L1-Fc) was immobilized on the particles. The IRF value of 68Ga radionuclide-labeled nanobodies (VHH) against PD-L1 (68Ga-VHH-PD-L1) was determined using magnetic particles coated with antigen molecules and cells expressing the antigen on their surface. When VHH antibodies were conjugated to 68Ga radionuclide, protein molecules were modified using bifunctional chelating agents: tetraazacyclododecanetetraacetic acid (DOTA) or deferoxamine (DFO). The magnitude of IRF was defined as the ratio of radioactivity specifically bound to particles or cells to the total radioactivity added to the sample.ResultsThe specificity of the 68Ga-VHH-PD-L1 radioimmunoconjugate binding to the antigen-coated magnetic particles has been proved. Some special aspects, which should be taken into consideration when using this method, have been established. The comparison of the IRF estimates using the antigen-expressing cells and magnetic particles has not revealed any significant differences in the results obtained in our study. Nevertheless, the presented method based on magnetic particles with immobilized antigen molecules requires only 15 min to determine the radioimmunoconjugate IRF, which is of fundamental importance for the routine assessment of the specificity of radiopharmaceuticals containing short-lived isotopes.
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