Search Results (66)

Allium ursinum (wild garlic) has long been collected and consumed as food and medicine in the north temperate zone, where its popularity is growing. Colchicum autumnale and Convallaria majalis contain toxic alkaloids. Their habitats overlap, and without flowers, their vegetative organs are similar. Confusing the leaves of Colchicum or Convallaria with the leaves of wild garlic has repeatedly led to serious human and animal poisonings. Our goal was to find a histological characteristic that makes the separation of these leaves clear. We compared the anatomy of foliage leaves of these three species grown in the same garden (Debrecen, Hungary, Central Europe). We used a bright-field microscope to characterize the transversal sections of leaves. Cell types of epidermises were compared based on peels and different impressions. We established some significant differences in the histology of leaves. The adaxial peels of Allium consist of only “long” cells without stomata, but the abaxial ones show “long”, “short” and “T” cells with wavy cell walls as a peculiarity, and stomata. Convallaria and Colchicum leaves are amphystomatic, but in the case of Allium, they are hypostomatic. These traits were confirmed with herbarium specimens. Our results help to clearly identify these species even in mixed, dried plant material and may be used for diagnostic purposes. Full article

Fractures in marine sediments are critical zones for hydrate formation. The kinetics and morphological characteristics of hydrates within sandstone fractures are comprehensively investigated in this study by employing a high-pressure visualization reaction vessel to examine their formation, dissociation, and reformation processes. The results are presented below: (1) In 3 mm Type I fractures, the induction time is longer than that observed in the other two fracture widths. Hydrates predominantly form on the fracture walls and gradually expand toward both sides of the fracture. (2) Gas enters the fracture from multiple directions, causing the hydrate in Type X fractures to expand toward the center from all sides, which shortens the induction time and increases the quantity of hydrate formation. (3) An increase in fracture roughness promotes nucleation of the hydrate at surface protrusions but inhibits the total quantity of hydrate formation. (4) Hydrate dissociation typically propagates from the fracture wall into the interior, exhibiting a wavy surface morphology. Gas production is influenced by the fracture width, with the highest gas production observed in a 3 mm fracture. (5) Due to the memory effect, the hydrate induction time for reformation is significantly shorter, though the quantity of hydrate formed is lower than that of the first formation. This study aims to provide micro-level insights into the distribution of hydrates in sandstone fractures, thereby facilitating more efficient and safe extraction of hydrates from fractures. Full article

The goal of the present investigation is to explore the heater position and tilting angle of geometry on a buoyant convective stream and energy transport in a tilted, curved porous cavity. This work can be utilized in the field of solar panel construction and electrical equipment cooling. Since no study has explored the impact of the heater location in an inclined wavy porous chamber, three locations of the heater of finite length on the left sidewall, viz., the top, middle, and bottom, are explored. The stream through the porous material is explained by the Darcy model. The upper and lower walls, as well as the remaining area in the left wall, are covered with thermal insulation, while the curved right sidewall maintains the lower temperature. The governing equations and related boundary conditions are discretized by the finite difference approximations. The equations are then iteratively solved for different heater positions, inclinations, Darcy–Rayleigh number (Ra_D), and corrugation of the right walls. It is witnessed that the heater locations and cavity inclinations alter the stream and thermal fields within the curved porous domain. Furthermore, all heating zones benefit from improved heat conduction due to the right sidewall’s waviness and the tilted porous domain. Full article

This publication presents the results of research on selected quality features of sample models made using 3D printing technology from the Powder Bed Fusion (PBF) group and a material based on aluminum powder. Two quality areas were analyzed: tensile strength and geometric surface structure. Strength tests of thin-walled models were carried out for samples with four given thicknesses of 1, 1.4, 1.8, and 2 mm and four printing directions, namely, three in the XZ plane and one in the XY plane. The measurement of the geometric structure was carried out using optical measuring devices and by taking into account the assessment of roughness and waviness parameters. Using scanning electron microscopy (SEM), an analysis of the fracture of samples after rupture was carried out and the surface was assessed for technological defects created in the manufacturing process. The test results showed that for thin-walled sample models, there are certain technological limitations regarding the minimum sample thickness in the manufacturing process and that the strength of thin-walled models in relation to “solid” samples depends on both the sample thickness and the printing direction. Roughness parameters that determine functional quality characteristics such as friction and wear were determined and also showed a dependence on the printing direction. Full article

The thermal history of a part deposited via wire arc additive manufacturing (WAAM) and hence its as-built properties can vary significantly depending on the thermal management applied, especially for metallurgically complex materials. Thus, this work aimed to assess the feasibility of processing thin-walled Scalmalloy^® (Al-Mg-Sc-Zr) structures by WAAM while examining the effects of arc energy and heat dissipation on their response to direct age-hardening heat treatment (without solution annealing). As a complement, the geometry, porosity, and processing time of such parts were also analyzed. The walls were built via the cold metal transfer (CMT) deposition process with different arc energy levels in combination with near-immersion active cooling (NIAC) settings (as thermal management solution), as well as with natural cooling (NC), resulting overall in both low surface waviness and porosity levels. Based on hardness testing, the resultant Scalmalloy^® direct-aging response (relative increase in hardness after direct age-hardening from WAAM as-built state) depended more on the arc energy per unit length of deposit applied. In contrast, the other thermal management approaches (NIAC or NC) helped in maintaining Sc in a supersaturated solid solution during deposition. Thus, Scalmalloy^® strengthening was demonstrated as feasibly triggered by means of a post-WAAM direct age-hardening heat treatment solely. Additionally, in comparison with a thermally equivalent (same interpass temperature) condition based on NC, the NIAC technique allowed the achievement of such a positive result on direct-aging response with much shorter WAAM processing times, therefore improving productivity. Full article

Background: Nowadays, exotoxic substance intake is among the most frequently employed methods of suicide. Self-poisoning is quite common among psychiatric patients treated in hospitals. Psychotropic drugs used for suicide include phenothiazines. Promazine hydrochloride (Talofen©) is an alpha-lytic phenothiazine neuroleptic with a high affinity for histaminergic H1 receptors and a low affinity for dopaminergic D2, serotoninergic 5-HT, alpha1-adrenergic, and muscarinic receptors, which may explain its potent sedative effect. The most common adverse effects include extrapyramidal syndromes, weight gain, orthostatic hypotension, QTc prolongation, convulsions, delirium, and psychosis. Rare adverse events include the potential occurrence of autoimmune syndromes and vasculitis. Methods: We report herein the delayed death of a 59-year-old woman due to cardiocirculatory arrest on an arrhythmic basis in the context of vasculitis of the small pulmonary vessels and prolongation of the QTc interval secondary to voluntary acute intoxication with promazine hydrochloride. Results: The incident occurred in a psychiatric patient with a history of prior self-harming acts. Histological investigations revealed wavy fibers in the heart, a lymphocytic granulocyte infiltrate in the walls of small- and medium-caliber vessels, and spotty perivascular deposition of histiocyte-macrophage cells in the lungs. Immunophenotypic investigations showed the prevalence of CD15+ and T-CD3+ elements, thus identifying a small vessel vasculitis. These findings were consistent with the literature regarding adverse events following the intake of promazine hydrochloride, although vasculitis is rare. Conclusions: Thus, while QTc lengthening and arrhythmic incidents are widely reported events associated with promazine hydrochloride use, the development of a rare condition such as pulmonary vasculitis undoubtedly played a synergistic and decisive stressogenic role in the genesis of the cardiac event, leading to irreversible functional arrest. Full article

In order to figure out the wall effect on the propulsive property of an auto-propelled foil, the commercial open-source code ANSYS Fluent was employed to numerically evaluate the fluid dynamics of flexible foil under various wall distances. A virtual model of NACA0015 foil undergoing travelling wavy motion was adopted, and the research object included 2D and 3D models. To capture the foil’s moving boundary, the dynamic grid technique coupled with the overlapping grid was utilized to realize the foil’s positive deformation and passive forward motion. The ground wall effect on fluid dynamics (thrust force, lift force and propulsive efficiency) and the flow structures of travelling wavy foil were analyzed. The numerical results show that the existence of the ground wall is beneficial for the propulsive property of foil. Specifically, the existence of the wall can improve the forward speed and efficiency of foil, with a maximum increase of 13% in moving velocity and a 10.5% increase in propulsive efficiency. The conclusions acquired in the current study are of great significance for the design of bionic UUV. Full article

Laser based-powder bed fusion (LB-PBF) enables fast, efficient, and cost-effective production of high-performing products. While advanced functionalities are often derived from geometric complexity, the capability to tailor material properties also offers significant opportunities for technical innovation across many fields. This study explores the optimization of the LB-PBF process parameters for producing Ti6Al4V titanium alloy parts with controlled porosity. To this end, cuboid and lamellar samples were fabricated by systematically varying laser power, hatch distance, and layer thickness according to a full factorial Design of Experiments, and the resulting specimens were thoroughly characterized by analyzing envelope porosity, surface roughness and waviness, surface morphology, and surface area. A selection of specimens was further examined using small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) to investigate the atomic structure and nanometric porosity of the material. The results demonstrated the possibility to finely control the porosity and surface characteristics of Ti6Al4V within specific LB-PBF process ranges. The pores were found to be mostly closed even for thin walls, while the surface roughness was recognized as the primary factor impacting the surface area. The lamellar samples obtained by exposing single scan tracks showed nearly an order-of-magnitude increase in both surface area and pore volume, thereby laying the groundwork for the production of parts with optimized porosity. Full article

The leaf surface micromorphology and the size of the stomatal complex of hybrids in the eighth seed generation from the crossing of ×Trititrigia cziczinii × Elymus farctus (f11814) on the wheat-like wheat-wheatgrass hybrid w107 were investigated by performing scanning electron microscopy of frozen samples (cryoSEM). The micromorphological characteristics of the paternal plants (w107) were dominant in the hybrid leaves. Costal long cells with silicified wavy walls, characteristic of w107 but absent in the mother plants f11814 and E. farctus, were observed in all hybrid samples examined. Conversely, shield-shaped prickles, a characteristic feature of E. farctus, were retained only in some hybrids. In addition, the maternal feature of Ω-shaped junctions of long epidermal cells in the intercostal zone was completely absent in hybrids. Quantitative parameters of the stomatal apparatus showed a weak correlation with micromorphological markers. Stomatal density on the adaxial side was inversely correlated with stomatal size, while variation in these parameters on the abaxial side occurred independently. The prevalence of paternal micromorphological traits in the hybrids seems to be a consequence of the elimination of genetic material from E. farctus, analogous to the loss of chromosomes from wild species observed in other distant crosses. Full article

Background: Neonatal rats that receive sucrose during a critical postnatal period (CP, days 12 to 28) develop hypertension by the time they reach adulthood. Inflammation might contribute to changes during this period and could be associated with variations in the vascular smooth muscle (VSMC) phenotype. Objective: We studied changes in inflammatory pathways that could underlie the expression of the secretory phenotype in the VSMC in the thoracic aorta of rats that received sucrose during CP. Methods: We analyzed histological changes in the aorta and the expression of the COX-2, TLR4, iNOS, eNOS, MMP-2 and -9, and β- and α-actin, the quantities of TNF-α, IL-6, and IL-1β using ELISA, and the levels of fatty acids using gas chromatography. Results: The aortic wall presented disorganization, decellularization, and wavy elastic fibers and an increase in the lumen area. The α- and β-actin expressions were decreased, while COX-2, TLR4, TNF-α, and the activity of IL-6 were increased. Oleic acid was increased in CP in comparison to the control group. Conclusions: There is transient hypertension at the end of the CP that is accompanied by inflammation and a change in the phenotype of VSMC to the secretory phenotype. The inflammatory changes could act as epigenetic signals to determine the development of hypertension when animals reach adulthood. Full article

Cold bending forming is a complex forming process, and its product quality is closely related to the forming process parameters. To mitigate issues such as bulging and waviness arising from the extension of the material at the edges during the forming process of thin-walled circular tubes, a comprehensive comparative analysis was conducted on four forming methods. This analysis determined that the combined bending method is the optimal forming technique for the equipment. For the impact of different parameters on the equivalent plastic strain distribution of the product and the force on the rollers, numerical simulations were carried out using the software COPRA (COPRA FEA RF 2023.1) after designing the pattern diagram based on the integrated bending method. The results showed that different processing speeds on the equivalent plastic strain distribution and work hardening of the plate have little effect. As the spacing between the upper and lower rollers increases, the equivalent plastic strain of the plate to a certain extent and the value of the moment of the rollers is significantly reduced. Analyzing the performance characteristics of high-strength steel materials from the aspects of the thickness strain and cross-sectional forming of the plate, this verifies the advantages of forming high-strength steel plates. The numerical simulation results of this study are in good agreement with actual production experimental results. Full article

Cytokinesis in plant cells begins with the fusion of vesicles that transport cell wall materials to the center of the cell division plane, where the cell plate forms and expands radially until it fuses with the parental cell wall. Vesicle fusion is facilitated by trans-SNARE complexes, with assistance from Sec1/Munc18 (SM) proteins. The SNARE protein KNOLLE and the SM protein KEULE are required for membrane fusion at the cell plate. Due to the crucial function of KEULE, all Arabidopsis (Arabidopsis thaliana) keule mutants identified to date are seedling lethal. Here, we identified the Arabidopsis serrata4-1 (sea4-1) and sea4-2 mutants, which carry recessive, hypomorphic alleles of KEULE. Homozygous sea4-1 and sea4-2 plants are viable and fertile but have smaller rosettes and fewer leaves at bolting than the wild type. Their leaves are serrated, small, and wavy, with a complex venation pattern. The mutant leaves also develop necrotic patches and undergo premature senescence. RNA-seq revealed transcriptome changes likely leading to reduced cell wall integrity and an increase in the unfolded protein response. These findings shed light on the roles of KEULE in postembryonic development, particularly in the patterning of rosette leaves and leaf margins. Full article

In this research, the wavy ice patterns that form due to the evolution of morphological perturbations on the water–ice phase transition interface in the presence of a fluid flow are studied. The mathematical model of heat transport from a relatively warm fluid to a cold wall includes the mechanism of convective–conductive heat transfer in liquid and small sinusoidal perturbations of the water–ice interface. The analytical solutions describing the main state with a flat phase interface as well as its small morphological perturbations are derived. Namely, the migration velocity of perturbations and the dispersion relation are found. We show that the amplification rate of morphological perturbations changes its sign with variation of the wavenumber. This confirms the existence of two different crystallization regimes with (i) a stable (flat) interfacial boundary and (ii) a wavy interfacial boundary. The maximum of the amplification rate representing the most dangerous (quickly growing) perturbations is found. The theory is in agreement with experimental data. Full article

During the production of components, manufacturers of structures are obliged to meet certain requirements and ensure appropriate quality characteristics. It is especially important during the manufacturing of thin-walled structures, which are subject to many errors during machining due to the reduced rigidity of the products, including the deformation of thin walls, which may be the result of the vibration of the system. The appearance of vibrations reduces the quality of the machined surface affecting the increase in the values of surface topography parameters—waviness and roughness. Thin-wall structures—titanium or nickel alloy, among others—play a key role in the aerospace industry, which constantly strives to reduce the weight of the entire structure while meeting requirements. The present work focuses on the evaluation of the parameters of surface topography, dimensional and shape accuracy during the milling of nickel alloy Inconel 625 samples containing a thin wall in a vertical orientation. The experiment was conducted under controlled cutting conditions using a constant material removal rate. As part of the surface topography section, the distribution of waviness, Wa and Wz, and roughness, Ra and Rz, was determined in selected measurement areas in the direction parallel to the direction of the feed motion. Dimensional deviations, measured with a 3D optical scanner, were determined in selected cross sections in the direction perpendicular and parallel to the bottom of the sample presenting the deflection of the thin-walled structure. The results provide information that the used parameter sets affect the measured quantities to varying degrees. Full article

Titanium and nickel alloys are used in the creation of components exposed to harsh and variable operating conditions. Such components include thin-walled structures with a variety of shapes created using milling. The driving factors behind the use of thin-walled components include the desire to reduce the weight of the structures and reduce the costs, which can sometimes be achieved by reducing the machining time. This situation necessitates, among other things, the use of new machining methods and/or better machining parameters. The available tools, geometrically designed for different strategies, allow working with similar and improved cutting parameters (increased cutting speeds or higher feed rates) without jeopardizing the necessary quality of finished products. This approach causes undesirable phenomena, such as the appearance of vibrations during machining, which adversely affect the surface quality including the surface roughness. A search is underway for cutting parameters that will minimize the vibration while meeting the quality requirements. Therefore, researching and evaluating the impact of cutting conditions are justified and common in scientific studies. In our work, we have focused on the quality characteristics of horizontal thin-walled structures from Ti₆Al₄V titanium alloys obtained in the milling process. Our experiments were conducted under controlled cutting conditions at a constant value of the material removal rate (2.03 cm³⁄min), while an increased value of the cut layer was used and tested for use in finishing machining. We used three different cutting tools, namely, one for general purpose machining, one for high-performance machining, and one for high-speed machining. Two strategies were adopted: adaptive face milling and adaptive cylindrical milling. The output quantities included the results of acceleration vibration amplitudes, and selected surface topography parameters of waviness (W_a and W_z) and roughness (R_a and R_z). The lowest values of the pertinent quantities were found for a sample machined with a high-performance tool using adaptive face milling. Surfaces typical of chatter vibrations were seen for all samples. Full article