Surface Of Vessel Research Articles

Cellular heterogeneity and stem cells of vascular endothelial cells in blood vessel formation and homeostasis: Insights from single-cell RNA sequencing.

Vascular endothelial cells (ECs) that constitute the inner surface of blood vessels are essential for new vessel formation and organ homeostasis. ECs display remarkable phenotypic heterogeneity across different organs and the vascular tree during angiogenesis and homeostasis. Recent advances in single cell RNA sequencing (scRNA-seq) technologies have allowed a new understanding of EC heterogeneity in both mice and humans. In particular, scRNA-seq has identified new molecular signatures for arterial, venous and capillary ECs in different organs, as well as previously unrecognized specialized EC subtypes, such as the aerocytes localized in the alveolar capillaries of the lung. scRNA-seq has also revealed the gene expression profiles of specialized tissue-resident EC subtypes that are capable of clonal expansion and contribute to adult angiogenesis, a process of new vessel formation from the pre-existing vasculature. These specialized tissue-resident ECs have been identified in various different mouse tissues, including aortic endothelium, liver, heart, lung, skin, skeletal muscle, retina, choroid, and brain. Transcription factors and signaling pathways have also been identified in the specialized tissue-resident ECs that control angiogenesis. Furthermore, scRNA-seq has also documented responses of ECs in diseases such as cancer, age-related macular degeneration, Alzheimer's disease, atherosclerosis, and myocardial infarction. These new findings revealed by scRNA-seq have the potential to provide new therapeutic targets for different diseases associated with blood vessels. In this article, we summarize recent advances in the understanding of the vascular endothelial cell heterogeneity and endothelial stem cells associated with angiogenesis and homeostasis in mice and humans, and we discuss future prospects for the application of scRNA-seq technology.

Spatiotemporal microvascular changes following contusive spinal cord injury.

Microvascular integrity is disrupted following spinal cord injury (SCI) by both primary and secondary insults. Changes to neuronal structures are well documented, but little is known about how the capillaries change and recover following injury. Spatiotemporal morphological information is required to explore potential treatments targeting the microvasculature post-SCI to improve functional recovery. Sprague-Dawley rats were given a T10 moderate/severe (200 kDyn) contusion injury and were perfuse-fixed at days 2, 5, 15, and 45 post-injury. Unbiased stereology following immunohistochemistry in four areas (ventral and dorsal grey and white matter) across seven spinal segments (n = 4 for each group) was used to calculate microvessel density, surface area, and areal density. In intact sham spinal cords, average microvessel density across the thoracic spinal cord was: ventral grey matter: 571 ± 45 mm-2, dorsal grey matter: 484 ± 33 mm-2, ventral white matter: 90 ± 8 mm-2, dorsal white matter: 88 ± 7 mm-2. Post-SCI, acute microvascular disruption was evident, particularly at the injury epicentre, and spreading three spinal segments rostrally and caudally. Damage was most severe in grey matter at the injury epicentre (T10) and T11. Reductions in all morphological parameters (95-99% at day 2 post-SCI) implied vessel regression and/or collapse acutely. Transmission electron microscopy (TEM) revealed disturbed aspects of neurovascular unit fine structure at day 2 post-SCI (n = 2 per group) at T10 and T11. TEM demonstrated a more diffuse and disrupted basement membrane and wider intercellular clefts at day 2, suggesting a more permeable blood spinal cord barrier and microvessel remodelling. Some evidence of angiogenesis was seen during recovery from days 2 to 45, indicated by increased vessel density, surface area, and areal density at day 45. These novel results show that the spinal cord microvasculature is highly adaptive following SCI, even at chronic stages and up to three spinal segments from the injury epicentre. Multiple measures of gross and fine capillary structure from acute to chronic time points provide insight into microvascular remodelling post-SCI. We have identified key vascular treatment targets, namely stabilising damaged capillaries and replacing destroyed vessels, which may be used to improve functional outcomes following SCI in the future.

Analysis of the shapes of clay vessels from the Chekanovsky Log-2 burial ground of the An-dronovo (Fedorovo) Culture in the foothills of Altai

The shapes of 32 vessels from the burials of Chekanovsky Log-2 cemetery were examined by a technique applied within the historical-and-cultural approach to study pottery shapes. The analysis was carried out at the levels of general proportionality of the shape, its natural structure, and the formedness of the functional parts. The aim of the study was to characterize the pottery traditions of the Andronovo population in terms of pottery shaping and to clarify their cultural dynamics. As the result, two mass traditions were identified, manifested by vessels of similar overall proportionality (35–36 degrees) but of two different structural types: ‘Lip+Neck+Pre-Shoulder+ Body+Body Base’ (5 parts) and ‘Lip+Pre-Shoulder+Body+Body Base’ (4 parts). Comparative analysis of the ves-sels from two excavated sections of the burial ground (northern and southern), making use of the information about other morphological features of the vessels (decoration and surface treatment), as well as about the speci-fics of the burial ritual, enabled revealing the dynamics in the development of the considered pottery traditions and the cultural composition of the population that used the burial ground. It appears that the vessels of 5-part shapes with a fully formed body and a more pronounced neck tend to the classical Andronovo (Fedorovo) period. They are characterized by burnished surface and ornamentation with fine-toothed stamps in a variety of geometric mo-tifs. The vessels of these shapes prevail in the burials of the northern dig, which demonstrated considerable cul-tural homogeneity. The vessels of 5-part shapes with a partly-formed body and a lower neck, along with 4-part shapes, probably became more widespread in the Late Fedorovo period. These items were less thoroughly bur-nished, but, more often, smoothed, with simplified ornamentation applied with a coarse-toothed or smooth stamp. These traditions are represented to a greater extent in the southern dig, which, in addition, appeared to be not so homogeneous due to the distribution of squater pots of various structures. This peculiarity may attest to the in-creasing complexity of the cultural composition of the population and intensification of cultural contacts at the late stage of the burial ground.

Characterization of ultracold neutron production in thin solid deuterium films at the PSI Ultracold Neutron source

We determined the ultracold neutron (UCN) production rate by superthermal conversion in the solid deuterium $({\mathrm{sD}}_{2})$ moderator of the UCN source at the Paul Scherrer Institute (PSI). In particular, we considered low amounts of less than 20 mol of ${\mathrm{D}}_{2}$, deposited on the cooled moderator vessel surfaces in thin films of a few mm in thickness. We measured the isotopic $({c}_{\text{HD}}<0.2%)$ and isomeric $({c}_{\text{para}}\ensuremath{\le}2.7%)$ purity of the deuterium to conclude that absorption and up-scattering at 5 K have a negligible effect on the UCN yield from the thin films. We compared the calculated UCN yield based on the previously measured thermal neutron flux from the heavy water thermal moderator with measurements of the UCN count rates at the beamports. We confirmed our results and thus demonstrated an absolute characterization of the UCN production and transport in the source by simulations.

Pottery of the Kalinkino Culture from the Barsov Gorodok III/2 Settlement: Technical and Technological Characteristics

Purpose. Barsova Gora is a unique archaeological and landscape site located in the Tyumen Region (West Siberia) of the Russian Federation. The technical and technological analysis of Kalinkino ceramics from the Barsov gorodok III/2 settlement (25 vessels) was performed in accordance with the method developed by A. A. Bobrinsky.Results. For the manufacture of vessels at the Barsov gorodok III/2 settlement, ferruginous clays were selected. Five subspecies of clay have been identified, differing in the sandiness degree and natural impurities composition. The most common subspecies of clay is weakly sandy clay with natural inclusions of brown ironstone. Three recipes for molding compond were defined: 1) clay + chamotte (21 vessels); 2) clay + chamotte + sand (3 vessels); 3) clay + sand (1 vessel). Vessels were made using patchwork molding, presumably on a base mold. Surfaces of vessels were processed by mechanical smoothing and glossing. There are 10 variants of combining different tools. The most common variant is smoothing vessel both surfaces using a serrated tool. Firing of pottery could take place in reducing or semireducing gas environment.Conclusion. A comparison of pottery traditions of the Kalinkino culture from the Barsov gorodok III/2 settlement and the Barsova Gora III/20 settlement revealed their similarity. It is manifested in the selection of weakly sandy ferruginous clays for vessels production. The dominant recipe for molding compound on both sites is clay + chamotte. Vessels were made using patchwork overlay. There are differences in the range of artificial additives used in the ceramic production, recipes for molding compound, surface treatment options. Pottery of the Kalinkino culture from the Barsov Gorodok III/2 settlement demonstrates similarity with the Barsovo culture products. The similarity is manifested in the use of weakly sanded ferruginous clays and the use of chamotte as the main mineral impurity. It also converges with the pottery of the Surgut variant of the Kulay cultural-historical community due to use of chamotte and patchwork overlay. However, there are significant differences between ceramics of the Surgut variant of the Kulay cultural-historical community and the Kalinkino culture from the Barsov gorodok III/2 settlement manifested: it lies in the use of shadings and flap veneer in the Kulay pottery.

Recent achievements in R&D on fibre optics current sensor for ITER

ITER is expected to achieve new milestones on the way to commercial fusion energy production. This will be still a research machine where numerous diagnostic systems are deployed, both already used on existing tokamaks and developed specifically for burning plasma operation. One of the innovative diagnostics is the Fibre Optics Current Sensor (FOCS). This paper describes recent results of the ITER FOCS development, concentrating on the front-end design. The FOCS sensing fibre, likely acrylate coated, will be located directly on the external surface of the vacuum vessel. During operation, it will be exposed to temperatures of 100–110 °C and multi-MGy level total radiation doses, while during vacuum vessel baking intervals the temperature will be 200–210 °C with low levels of radiation. Such temperatures are outside the nominal range for acrylate coatings even for acrylate coatings specially designed for high temperature applications. We provide experimental results that indicate that acrylate coated fibres FOCS fibres nevertheless can survive ITER environment without critical degradation and attribute this to the system design, for which the fibre operates in an inert gas (neon) atmosphere.

Spread of premalignant mutant clones and cancer initiation in multilayered tissue

Over 80% of human cancers originate from the epithelium, which covers the outer and inner surfaces of organs and blood vessels. In stratified epithelium, the bottom layers are occupied by stem and stem-like cells that continually divide and replenish the upper layers. In this work, we study the spread of premalignant mutant clones and cancer initiation in stratified epithelium using the biased voter model on stacked two-dimensional lattices. Our main result is an estimate of the propagation speed of a premalignant mutant clone, which is asymptotically precise in the cancer-relevant weak-selection limit. We use our main result to study cancer initiation under a two-step mutational model of cancer, which includes computing the distributions of the time of cancer initiation and the size of the premalignant clone giving rise to cancer. Our work quantifies the effect of epithelial tissue thickness on the process of carcinogenesis, thereby contributing to an emerging understanding of the spatial evolutionary dynamics of cancer.

Molecular and Cellular Aspects of the Endothelial-Mesenchymal Transition in Cardiovascular Diseases

Endothelial cells (ECs), which form the inner surface of the blood vessels, contact the blood, withstand mechanical pressure, and demonstrate heterogeneous reactions to exogenous and endogenous stimuli. ECs have unique properties in accordance with their niches and play an important role in regulating vascular homeostasis. Endothelial cells may undergo a dynamic phenotypic switch in terms of its heterogeneity, which may lead to endothelial dysfunction and a number of associated pathologies. Endothelial-mesenchymal transition (EndMT) is one of the possible molecular and cellular mechanisms of this kind. EndMT is characterized by phenotypic changes in ECs through which endothelial cells acquire new properties, i.e., start producing mesenchymal markers such as alpha-SMA and vimentin, change morphology, and become able to migrate. EndMT is a complex biological process that can be induced by inflammation, hypoxia, or oxidative stress and be involved in pathogenesis of cardiovascular disease. This review describes the key markers, inhibitors, and inducers of endothelial-mesenchymal transition and overall state-of-the-art of EndMT in cardiovascular diseases.

Topography and Composition of the Iliolumbar Veins in a South African Cohort: Implications for Spinal Surgery.

A descriptive cross-sectional study of the anatomical variations, morphometry, and histology of the iliolumbar veins (ILVs). This study aimed to describe the anatomical variations of the ILVs and determine their tissue composition in South African cadavers of European descent. A safe anterior surgical approach to the L4/L5 intervertebral disc space requires understanding the anatomy of the ILVs. Limited understanding of ILVs and their variations may lead to inadvertent avulsion of veins with subsequent hemorrhage and damage to the adjacent nerves intraoperatively. Variations in ILVs are population specific, but such reports are limited in the South African population. Eighty-nine adult cadavers were dissected to reveal ILV patterns. The variations (origin, course, and drainage pattern), morphometries, and topography of the ILVs were studied. A total of 19 (10 proximal, nine distal) ILVs were processed for hematoxylin and eosin, Masson's trichrome, and Verhoeff's histological staining to determine the tissue composition. The ILVs were identified in 100% of the cases, and 45% of the ILVs were anastomosed to each other bilaterally. The rightside ILVs terminated into the posterior surfaces of the iliac vessels (p =0.001), whereas the left-side ILVs terminated into the lateral surfaces (p =0.001). The left-side proximal ILVs had higher elastic fiber composition (p =0.030). The ratio of the ILVs' elastic fibers to collagen fibers was 1:9, and 61% of the cadavers exhibited type 1 ILV pattern. Moreover, 42% of the ILVs were at the S1 vertebral level with 31% lying between L4 and L5 spinal nerve roots. The obturator nerve coursed anteriorly to the ILVs in 96% of cases. The ILV variations described for South Africans present new additional patterns, such as bilateral anastomosis and laterality of the terminal drainage. The ILVs have more collagen fibers than elastic fibers, predisposing them to avulsion during surgical retraction. The identification of all the ILVs is crucial to minimize inadvertent hemorrhage and damage to adjacent structures.

Noninvasive liquid level sensing with laser generated ultrasonic waves

This article proposes a noninvasive liquid level sensing technique using laser-generated ultrasound waves for nuclear power plant applications. Liquid level sensors play an important role of managing the coolant system safely and stably in the plant structure. Current sensing techniques are mostly intrusive, performing inside the fluidic structure, which is disadvantageous in terms of the regular maintenance of the plant system. Furthermore, typical intrusive sensors do not perform stably under varying environmental conditions such as temperature and radiation. In this study, sensing units are attached to the outer surface of a liquid vessel to capture guided ultrasound waves in a nonintrusive manner. The signal intensity of the guided wave dissipates when the signal interacts with the internal liquid media. The sensing mechanism is mathematically expressed as an index value to correlate the liquid level with the sensor signal. For the acoustic wave generation, laser-generated ultrasound was adopted instead of using typical contact type transducers. Following the simulation validation of the proposed concept, the performance of the developed sensor was confirmed through experimental results under elevated liquid temperature conditions. The nonlinear multivariable regression exhibited the best-fit to the datasets measured under the variable liquid level and temperature conditions.

Energy Consumption Analysis of a Continuous Flow Ohmic Heater with Advanced Process Controls

This paper presents an analysis of the energy consumption of a continuous flow ohmic heater (CFOH) with advanced process controls for heating operations in the food and drinks industry. The study was carried out by using operational data collected from a CFOH pilot plant that was designed and constructed at the National Centre of Excellence for Food Engineering (NCEFE), Sheffield Hallam University. The CFOH is controlled by a PC and includes an onboard Programmable Logic Controller (PLC) and a Human Machine Interface (HMI) so that it can be operated as a stand-alone unit with basic on/off and power setting control but without any advanced control features. The technical solution presented in this paper for heating foods demonstrates significant energy saving compared with conventional heating methods. Using the CFOH, the electric current generated in the food products by the Joule effect produces a rapid temperature increase with very high energy efficiency. This technique eliminates the low efficiency of heat transfer from the surface of vessels typically used to heat and cook food products. The analysis presented in this paper describes the energy consumption of the CFOH and compares the efficiency of the CFOH when different advanced process control techniques are used. Experimental results and analysis have shown that the CFOH can achieve an energy efficiency conversion of at least 87.9%. It has also shown that the energy conversion percentage can be increased by applying advanced controllers such as model predictive control (MPC) or adaptive model predictive control (AMPC).

Effects of shear stress on the properties of colonyforming endothelial cells in comparison with coronary artery endothelial cells

Highlights. It is assumed that pre-colonization by endothelial cells of the inner surface of tissue-engineered vessels of small diameter can serve as an effective way to prevent thrombosis. The question of choosing the optimal source of endothelial cells for use in tissue engineering remains debatable. The paper considers the features of the culture of colony-forming endothelial cells obtained from the peripheral blood of patients with coronary heart disease, in comparison with mature endothelial cells from the coronary artery.Aim. To study the effect of laminar flow on the morphological and functional characteristics of mature endothelial cells and peripheral blood-derived endothelial colony-forming cells.Methods. Coronary artery endothelial cells were purchased from the Cell Applications, Inc. Colony-forming endothelial cells were obtained from the peripheral blood of patients with coronary artery disease who underwent percutaneous coronary intervention. The cells were isolated using a Ficoll gradient and cultured in EGM-2MV culture medium containing 5% fetal bovine serum. The cells of the experimental group were cultured in µ-Luer plates in a perfusion system with a shear stress of 3 dyn/cm2 . The cultivation time was 2 days. The cells of the control group were cultured under static conditions. At the end of the cultivation we performed immunofluorescent staining for CD31, KDR/CD309, CD144, vWF, type IV collagen, F-actin.Results. Colony-forming endothelial cells and coronary artery endothelial cells retained high density and viability both under static and laminar flow conditions. Shear stress stimulated a change in the phenotype of colony-forming endothelial cells towards a mature endothelial cells, in particular, a significant increased the expression of KDR/CD309 and CD31. The action of laminar flow reduced the synthesis of von Willebrand factor, stimulated the synthesis of type IV collagen. Shear stress promoted the development of structural rearrangements in cells in response to transduction, which manifested in a change in F-actin fibrils orientation on the flow direction.Conclusion. Colony-forming endothelial cells showed a characteristic response to the action of shear stress, consisting in a change in morphology, phenotype, and secretory activity of cells, comparable to that of coronary artery endothelial cells.

Interaction of Two Growing Corrosion Pits on the Surface of a Spherical Pressure Vessel

Interaction of Two Growing Corrosion Pits on the Surface of a Spherical Pressure Vessel

A Robust Learned Feature-Based Visual Odometry System for UAV Pose Estimation in Challenging Indoor Environments

Unmanned Aerial Vehicles (UAVs) are becoming popular nowadays due to their versatility and flexibility for indoor applications, such as the autonomous visual inspection for the inner surface of a pressure vessel. Nevertheless, robust and reliable position estimation is critical for completing these tasks. Visual Odometry (VO) and Visual Simultaneous Localisation and Mapping (VSLAM) allow the UAV to estimate its position in unknown environments. However, traditional feature-based VO/VSLAM systems struggle to deal with complex scenes such as low illumination and textureless environments. Replacing the traditional features with deep learning-based features provides the advantage of handling the challenging environment, but the efficiency is ignored. In this work, an efficient VO system based on a novel lightweight feature extraction network for UAV onboard platforms has been developed. The Deformable Convolution (DFConv) is utilised to improve the feature extraction capability. Owing to the limited onboard computing capability, the Depth-wise Separable Convolution (DWConv) is adopted to calculate the offsets for the deformable convolution and construct the backbone network to improve the feature extraction efficiency. Experiments on public datasets indicate that the efficiency of the VO system is improved by 30.03% while preserving the accuracy on embedded platforms with the feature points and descriptors detected by the proposed Convolutional Neural Network (CNN). Moreover, the proposed VO system is verified through UAV flying tests in a real-world scenario. The results prove that the proposed VO system is able to handle the challenging environments where both the latest traditional and deep learning feature-based VO/VSLAM systems fail, and it is feasible for UAV self-localisation and autonomous navigation in the confined, low illumination and textureless indoor environment.

ПЕРСПЕКТИВЫ ИСПОЛЬЗОВАНИЯ ДЕЗИНФИЦИРУЮЩЕГО СРЕДСТВА НА ОСНОВЕ ПОРФИРИНОВОГО МАКРОЦИКЛА

The paper presents the incorporating method of FeIIICl-tetraphenylporphyrin (FeClTPP) into the poly-N-vinylpyrrolidone (PVP) polymeric matrix. The resulting FeClTPP-PVP complex was diluted to final concentrations of 10, 20, 40, 60, 80 and 100 mmol and deposited on the inner surfaces of glass vessels. These vessels were used to simulate the surfaces of objects of veterinary and sanitary control that require periodic disinfection. The antibacterial activity of indicated concentrations of FeClTPP-PVP against antibiotic-resistant gram-negative and gram-positive microorganisms – Escherichia coli (strain 1257) and Staphylococcus aureus (strain 209-P) was demonstrated. As these microorganisms are also representatives of the most frequently encountered contaminants, we have studied the prepared bacterial suspensions from daily cultures of E. coli and S. aureus in dilutions from 108 to 104 CFU/mL. After that, the artificial contamination of the inner surfaces of the test objects was carried out. Antibacterial activity was determined by the degree of inhibition and was recorded visually and spectrophotometrically (OD600 nm ). The inhibitory effect on the growth of E. coli and S. aureus was directly proportional to the concentration of FeClTPP-PVP and inversely proportional to the degree of microorganism’s dilution. The greatest effect (about 87% reduction in bacterial growth) was achieved by the influence of FeClTPP-PVP maximum concentration.

In Vivo Profiling of the Vascular Cell Surface Proteome in Murine Models of Bacteremia.

Vascular dysfunction is a hallmark of systemic inflammatory responses such as bacterial sepsis. The luminal surface of the blood vessels is coated with a dense layer of glycans and proteoglycans, collectively known as the glycocalyx. Surface associated glycoproteins of endothelial origin, or derived from pericytes, intravascular leukocytes, and plasma, are other important components of the glycocalyx, constituting a vascular cell surface proteome that is dynamic, tissue-specific, and sensitive to changes in vascular homeostasis, blood infection, and inflammation. Here, we describe an experimental protocol to chemically tag and quantify the vascular cell surface proteome in murine models of bacteremia, in a time-resolved and organ-specific manner. This method facilitates the identification of markers of vascular activation and provides a molecular framework to understand the contribution of vascular dysfunction to the organ pathology of systemic inflammation.

Analysis of Monocyte Recruitment During Inflammation by Intravital Imaging.

Monocytes play essential roles in the inflammatory and anti-inflammatory processes that take place during an immune response, acting both within the vascular network and interstitially. Monocytes are activated, mobilized, and recruited in response to an inflammatory stimulus or different forms of tissue injury. The recruitment of circulating monocytes to the inflamed tissue is essential to resolving the injury.Monocyte recruitment is a multistep process that begins with a decrease in rolling velocity, is followed by adhesion to the endothelium and crawling over the luminal vessel surface, and culminates in monocyte transmigration into the surrounding tissue. Intravital microscopy is a powerful visualization tool for the study of leukocyte behavior and function, intercellular interactions, cell trafficking, and recruitment in pathological and physiological conditions. This modality is therefore widely used for the detailed analysis of the immune response to multiple insults and the molecular mechanisms underlying monocyte interactions within the vascular system in vivo. This chapter describes a protocol for the use of intravital microscopy to analyze monocyte recruitment from the blood vessel to the inflammatory site.

Endothelial glycocalyx in hepatopulmonary syndrome: An indispensable player mediating vascular changes.

Hepatopulmonary syndrome (HPS) is a serious pulmonary vascular complication that causes respiratory insufficiency in patients with chronic liver diseases. HPS is characterized by two central pathogenic features-intrapulmonary vascular dilatation (IPVD) and angiogenesis. Endothelial glycocalyx (eGCX) is a gel-like layer covering the luminal surface of blood vessels which is involved in a variety of physiological and pathophysiological processes including controlling vascular tone and angiogenesis. In terms of lung disorders, it has been well established that eGCX contributes to dysregulated vascular contraction and impaired blood-gas barrier and fluid clearance, and thus might underlie the pathogenesis of HPS. Additionally, pharmacological interventions targeting eGCX are dramatically on the rise. In this review, we aim to elucidate the potential role of eGCX in IPVD and angiogenesis and describe the possible degradation-reconstitution equilibrium of eGCX during HPS through a highlight of recent literature. These studies strongly underscore the therapeutic rationale in targeting eGCX for the treatment of HPS.

An experience of the experimental use-wear analysis of made of tools pottery shards (based on the materials of the fortified settlement of Marai 4)

The paper concerns the determination of the functional purpose of scraper-shaped pottery tools of the forti-fied settlement of Marai 4 of the initial period of the Early Bronze Age. The site is located in the territory of the Lower Ishim River basin in Kazan District of Tyumen Oblast. Its materials are dated to the 6th (7th) — end of the 5th centuries BCE; culture-wise, they belong to the circle of the Zhuravlevo antiquities. The collection of the pot-tery scrapers of the site amounts to 78 items. Initially, the majority of them were interpreted as scrapers for fle-shing. However, a series of features gave rise to doubts, and the problem of the functional purpose of the scraper-like implements from Maray 4 remained open. In order to elaborate and correct the conclusions, in 2019–2022 the author conducted experiments on the use of pottery shards in the process of skin treatment, wood scraping, abrasive treatment of copper and bronze, in pottery making — at the stage of smoothing, compacting and sleeking the walls of pottery containers. The purpose of this paper is to present the results of the experimen-tal use-wear study of the scraper-like pottery artefacts from the Early Iron Age sites of Maray 4. The investigation is based upon the use of the experimental use-wear method, which involves the study of the traces of wear on the surface of implements, and their functional attribution. The use-wear analysis and microphotography of the traces of wear were carried out with the aid of a pancratic microscope MC-2 Z00M with a magnification from 10× to 40× with a Canon EOS-1100 camera. The performed studies allowed refining the previously conjectured hypothesis on the functional purpose of the scraper-shaped tools from Maray 4 and reaching the conclusion that most of them were used for smoothing and compacting the surface of pottery vessels. This conclusion is supported by the preliminary view of V.V. Ilyushina based upon the comparison of available reference experimental samples of surface treatment of clay vessels with pottery tools with the vessels from the site.

Passive heat removal in horizontally oriented micro-HTGRs

There are novel, horizontally oriented high-temperature gas-cooled micro-reactor (HTGR) designs under consideration because of their portability, simplicity, and reliable operation. These features of the micro-HTGR design can meet the fission battery attributes, such as economic, standardize, installed, unattended and reliable. Although there have been HTGR related safety studies, micro-HTGRs when horizontally oriented are expected to exhibit significantly different thermal physics. During the unavailability of helium circulation, the internal reactor core is designed to cool by block-to-block conduction and radiation, and the reactor vessel surface is cooled by the ambient air. This scenario is anticipated during the transport of the micro-HTGR in a shipping container. The conduction and radiation between the prismatic micro-HTGR blocks in the core can be influenced by variances in the thermal contacts. This work investigated the conduction within a simulated horizontal HTGR core. An experimental setup was used to validate a numerical model. The experimental setup consisted of a hexagonal assembly with scaled prismatic blocks placed within a high-temperature vacuum environment. The gaps between the blocks were well controlled and monitored. The experimental setup was designed in such a way that the temperature variation in the axial direction was minimal, such that the experiment could be observed as a 2D (r, θ) heat transfer problem. The pressurized tube was equipped with Infra-Red (IR) transparent windows, and an IR camera was used to capture the spatio-temporal temperature evolution in the hexagonal block assembly during the cooldown experiments. The experimental scenario was computationally modeled with a finite element analysis (FEA) program. Once validated, the computational model was used to investigate the impact of gap conductance on overall decay heat removal. Using a conservative estimate for gap conductance value (100 W/m2−K) between the prismatic blocks, there is a negligible increase in temperature observed during decay heat generation.