Connective Elements Research Articles

Bifenox induces hepatotoxicity and vascular toxicity in zebrafish embryos via ROS production and alterations in signaling pathways

Existing evidence shows that currently used pesticides pose toxicological risks to exposed wildlife. Chemically, bifenox belongs to diphenyl ethers, a well-known group of herbicides. Its mechanism of action primarily involves inducing lipid peroxidation and blocking protoporphyrinogen oxidases. Toxicity of diphenyl ether herbicides has been elucidated in animal cells; however, in vivo toxicological evaluations of bifenox are required to determine its unexpected effects. This study aimed to determine the negative effects of bifenox, and its effects on higher eukaryotes. We found that early stages of zebrafish embryo exposed to bifenox demonstrated increased mortality and physiological defects, based on the LC50 value. Bifenox severely inhibited blood vessel growth by reducing key elements of complex connectivity; fluorescently tagged transgenic lines (fli1a:EGFP) showed morphological changes. Additionally, transgenic lines that selectively identified hepatocytes (fabp10a:DsRed) showed reduced fluorescence, indicating that bifenox may inhibit liver development. To evaluate the level of oxidative stress, we used 2′,7′-dichlorofluorescein diacetate (DCFH-DA) probes in zebrafish embryos to identify the underlying mechanisms causing developmental damage. Our findings demonstrate that exposure to bifenox causes abnormalities in the hepatic and cardiovascular systems during zebrafish embryogenesis. Therefore, this study provides new information for the evaluation of toxicological risks of bifenox in vertebrates.

The Use of PVD Coatings for Anti-Wear Protection of the Press-In Connection Elements

Press-in connections are the commonly used methods for connecting machinery components. In relation to that wide use, those connections are liable to various types of damage and wear. Therefore, this article proposes one of the methods which may improve the life of the press-in connection. CrN+OX, TiN, and ZrN coatings made in the PVD technology were used. The coatings were applied on shafts mating with sleeves and subjected to a rotational bending moment. Tests and observations were conducted that enabled the assessment of the influence of those coatings on the development of wear, in particular fretting, in the tribological kinematic pair. The tests showed the development of wear on all the observed shaft surfaces, with a lower intensity of damage recorded on coated shafts compared to uncoated ones. The traces of fretting wear were noted each time at the edges of the connection, which is due to the mechanism of wear development under rotational bending conditions. In the case of uncoated shafts, wear occurs at the entire circumference of the axle seat in the form of a 3–4 mm wide ring; however, that width is different on either side. In the case of coated shafts, wear occurs on the circumference of the axle seat in the form of a thin ring 1–3 mm wide, depending on the coating. In the case of a ZrN coating, fretting wear appears locally. The largest surface area occupied by wear is 0.75 cm2. Fretting wear comprises mainly material build-ups, pits, and surface scratches. In addition to fretting wear, damage resulting from the process of forcing the sleeve onto the shaft was observed on the tested surfaces.

Retraction Note: Dynamic analysis of structures installed hysteretic dampers with hardening post-yielding stiffness using connection element method

Retraction Note: Dynamic analysis of structures installed hysteretic dampers with hardening post-yielding stiffness using connection element method

Towards the realization of composite metastructures: A failure analysis of connections

Metastructures hold significant potential for applications such as adaptive structures and soft robotics. Architectures of fiber-reinforced polymer metastructures may relate to modular arrangement of straight and curved laminates, with their connections to resemble perfect cracks, thus susceptible to delamination. This study investigated geometrical effects on the load-carrying capabilities of these connections upon a global tensile deformation, as well as lean modeling tools to facilitate the development of architected composite metastructures. Numerical fracture mechanics approach on different connection geometries and thicknesses showed that connection delamination is a critical failure mode, but crack-driving-force has low dependence on connection shape for given ligament thickness (and stiffness). Adopted analytical models could capture either moment or force-driven delamination failure, while the intermediate regime necessitates numerical tools. First-ply failure may precede depending on shape and ligament stiffness. These trends were also verified on an exemplary rotating chiral composite geometry. Furthermore, interface load-carrying capability improvements were studied via design considerations including connection filler material and element variable thickness. Indicatively, the latter showed a 157 % increase in bending deflection (and global deformations), while reducing crack driving force by 38 % for a given load case. The conducted analysis offers valuable insights into the design of lightweight, load-carrying composite metastructures.

Nonlinear dynamic collapse analysis of space semi-rigid frames using finite particle method

Based on the finite particle method, this work presents a general numerical method to perform the nonlinear dynamic collapse analysis of space semi-rigid structures. A space connection element composed of two particles and six zero-length springs is proposed to simulate the space semi-rigid connection. Geometrical nonlinearity is addressed through fictitious motion, while material and connection behavior nonlinearities are captured by updating the element stiffness matrix and the connection stiffness matrix, respectively. Member and connection fracture models are convenient for simulating fracture behaviors during collapse processes. To verify the effectiveness of the proposed method, the numerical results are compared with those from previous studies, and energy conversion analyses are adopted. The analysis results indicate that only member fractures occur at beam ends in the rigid and linear semi-rigid frames, while only connection fractures occur at beam ends in the nonlinear semi-rigid frame.

GIS-BASED REAL-TIME GAS LEAK DETECTION SYSTEM AT BASKENT NATURAL GAS DISTRIBUTION COMPANY

Abstract. Natural gas has been used for heating and production purposes in Turkey since 1987, and every passing year, the natural gas pipeline network continues to expand with investments. The distribution of natural gas within urban areas is achieved through a complex network structure formed by the joining of Polyethylene (PE) and Steel (ST) pipes using various connection elements. This complex structure is susceptible to deformation over time due to various reasons such as corrosion in steel lines, manufacturing errors in connection elements in PE lines, and other factors. As a result, natural gas leaks occasionally occur in these pipelines. The leakage control process in natural gas pipelines is carried out using specially designed equipment and vehicles equipped for this purpose. However, while these systems may be sufficient for collecting the necessary data for leak detection, the complex structure of the distribution network and the necessary data for leak detection, the complex structure of the distribution network and the necessity of performing this process with multiple teams bring about many challenges in terms of tracking, management, and reliability of the operation. At this point, the advancement of GIS (Geographic Information System), mobile, and communication technologies has made it possible to overcome these challenges. In this study, a real-time GIS-supported leak detection system developed using these technologies for Başkent Natural Gas Distrubition Inc. (Başkentgaz), which provides natural gas distribution services in Ankara, has been described. The study discusses the benefits brought by this system to the natural gas leak detection process.

Nonlinear Dynamic Analysis for a Jeffcott Rotor Considering Varying Connection Stiffness of Bolted Joint

Bolted joints have been widely used in rotor assemblies of aircraft engines. A typical bolt joint is composed of two metal parts connected mechanically with pre-tensioned bolts. During operations, the bolting pretensions can vary with the changing contacting relationship between the parts, which makes the connection stiffness of the joint nonlinear on the macroscopic scale. The fundamental problems of the dynamical analysis for bolted joints are (1) to identify the transition of the change of the connection stiffness and properly model the overall connection stiffness and (2) to investigate the influence of such variable stiffness on the rotor vibration. In this paper, an analytical model is proposed considering the effect of bolted joints. The bolt of the joint is simplified as a two-node spring-like connection element considering different axial tension and compression stiffness, non-uniform preload of bolts and the contact interface friction described based on Coulomb friction. The dynamic equations of the rotor system are established based on the lumped mass modeling and the proposed connection element, and numerically solved through the Runge–Kutta method. The results indicate that the rotor system exhibits a variety of states, such as period-1 motion, multi-period motion, quasi-periodic motion and chaotic motion. The effects of friction coefficient and preload of the bolts on the nonlinear dynamic behaviors of the bolted rotor system are demonstrated in detail.

Preliminary experimental tests of a novel friction damper for seismic retrofit of RC precast structures

Precast RC structures have been widely adopted for industrial and commercial buildings since the ’60 s in the most developed countries. For this structural typology, connections between structural elements set a crucial point in the presence of lateral loads, such as earthquakes, since the deficiency, or lacking, of connection elements is the main responsible for their structural collapse. This paper shows the preliminary mechanical testing of an innovative damping device conceived to be installed in beam-to-column joints of precast RC structures, with a bidirectional dissipative potential due to its geometry. This new Bidirectional Rotation Friction Damper (BRFD) has been designed and optimised after a tribological campaign, which led to the selection of the two different friction interfaces investigated in this work. The mechanical tests have been performed considering the guidelines of EN15129 and the previous tribological investigation findings, showing the influence of sliding frequency and bolt torque increment on the steadiness of the BRFD hysteresis cycle.

Promoting bridging in adhesively bonded composites with polymer inserts: A computational perspective

Preventing catastrophic failure due to delamination in adhesively bonded carbon fiber reinforced polymer (CFRP) is crucial to enhancing the reliability of structures. Experimental evidence from another study demonstrated that introducing inserts into the adhesive bond line creates bridging, effectively arresting the delamination process. In this paper, a numerical model was proposed to mimic the experiment and then utilized for conducting parametric studies. An embedded cell approach was adopted, representing a double cantilever beam (DCB) with linear-elastic continuum shell elements, beam elements for the bridging bundles, and connector elements for the adhesive. The crack propagation was initiated with adhesive failure and subsequently followed by bridging bundle failure. The numerical simulation results closely replicated the experiment’s global response in the force–displacement curve, thereby effectively validating the existence of the bridging effect. Furthermore, our study revealed that enhancing the adhesive strength and insert ductility can further improve crack resistance.

Exploring the Crucial Role of Maxillary Sinus in the Success of Dental Implants: A Comprehensive Review

The procedure known as maxillary sinus augmentation has been increasingly embraced by dental professionals, who are recognizing its value and efficacy. This comprehensive review article’s goal is to give a complete and current examination of several important features relating to the anatomy, physiology, and common clinical problems of the maxillary sinus in light of this expanding acceptance. Moreover, the review intends to highlight the clinical significance of these key elements in connection to the sinus augmentation operation and the subsequent placement of dental implants.

МЕТОДЫ МАГНИТНО-ИМПУЛЬСНОЙ СВАРКИ (ОБЗОР)

The article presents the features of various methods of pulsed welding in the solid phase using magnetic pressure according to a scheme with normal loading. A scheme of magnetic-pulse welding, implemented through electrical discharge cleaning without oblique impact, is described. Magnetic pressure is used for forming and welding. The authors proposed an original scheme for producing enclosing structures from dissimilar alloys by preheating the assembled unit in a vacuum, followed by crimping through the transmitting medium «shell» with an inductor according according to the «crimp» scheme. To obtain joints of the «rod-sheet» type in a heterogeneous combination of materials and structures of different thicknesses, the authors proposed to carry out a sequential connection of a magnetic hammer with the parts being welded, which allows synchronizing the process of thermal and force effects on the surfaces being welded. Various schemes for mating parts to be welded have been developed, including those using powder compositions as a connecting element. To implement the presented technological processes, universal special technological discharge-pulse equipment has been created, which makes it possible to implement the processes of welding, stamping, pressing, crimping, electric explosion of conductors and electrohydropulse processing of materials.

Efficiency of timber-concrete composite floors with discrete perfobond connections: A numerical study

To evaluate the behaviour of a single timber-concrete composite (TCC) T-beam, a simplified 2D finite element (FE) model in Abaqus is developed and validated using experimental tests and the Gamma method given in Annex B of EN 1995–1-1. The shear connection used in the beam consist of perfobond connectors, which are adhesively bonded to the timber beam. In the developed model, beam and shell finite elements have been used to simulate/reproduce the timber beam and the concrete slab, respectively. These have then been connected using connector elements which incorporate the mechanical behaviour of the tested shear connections, obtained in a previous research. After the successful validation of the FE model, this is used to further analyse different parameters such as: i) different number of connections (varying from 8 to 20), ii) different types of loading (point load, distributed load and line load), iii) different concrete slab widths and iv) connection models with elastic perfectly plastic behaviour applied to TCC T-beam and a 5 m by 5 m floor system. The results of the conducted study provide an in-depth understanding of the effect and impact of the investigated parameters which can support a future optimisation of the structural solution. Moreover, the results show that the use of a simplified 2D model can support designers to overcome the limitations of analytical approaches, such as the Gamma method, to analyse large spacing and to take benefit of bidirectional effects (load sharing) if analysed as a whole instead of a single T-beam.

A novel cable-net buffer device for recovering reusable launch vehicle: Design, dynamic modeling, and performance analysis

At present, reusable launch vehicle technology (RLV) has become a research hotspot in the aerospace field and one of the major development trends in this industry. With reference to the aircraft carrier’s arresting cable technology, this paper puts forward a novel cable-net buffer device for recovering the first stage of launch vehicle. The device can transfer load through a cable-pulley mechanism, and then complete the first stage recovery by losing the kinetic energy and gravitational potential energy of the first stage through hydraulic dampers and preloaded counterweights. In order to analyze the performance of this cable-net buffer device, the finite element software ABAQUS is adopted to establish a rigid-flexible coupling dynamic model. In this model, the cable-pulley mechanism is simulated by connector and shell elements, the damping force of the hydraulic dampers by VUAMP subroutine, and the preloaded counterweights by mass point. And then, performance evaluation indexes of this buffer device are proposed in this paper. Meanwhile, the dynamic simulation, using the established dynamic model, is carried out under different device design parameters and working condition parameters. On the one hand, the simulation results show that the tower span and damping force have remarkable effects on the buffer performance. On the other hand, among all working condition parameters, only the fall point deviation has a significant effect on the buffer performance, but this effect is less than that of the design parameters. Finally, combing the dynamic model and the surrogate model technique, this paper obtains feasible boundaries of design parameters of the device for the subsequent detailed design of it. Researches in this paper will provide new ideas for the development of RLV.

Digital technologies, closeness, and practices of being together in the context of the new normal in Serbia

At the beginning of 2020, the global community faced a dramatic collapse of everyday life due to the pandemic caused by the emergence of a new coronavirus. The widespread changes in both public and private life led to the breakdown of routines and rhythms of daily life as we knew them, ushering us into a period known as the new normal. One of the main characteristics of life in the new normal has been the requirement for physical distancing and the reduction of physical contacts, or physical isolation. Under these conditions, it has become noticeable that digital technologies have become the primary element and link for establishing and maintaining social connections within the complex network of human sociability, permeating all our social relations and interactions. With this in mind, in this paper, relying on ethnography from a methodological perspective and materially oriented ontology from a theoretical perspective, I will attempt to analyze and present the changes in practices of social connection, specifically the ways in which close social ties (family, friends, and partners) and new social practices and rituals, associated with the increased use of digital technologies under the conditions of the new normal, mutually constitute each other. In this paper, the new normal is perceived as a period of uncertainty and continuous waiting, where waiting is not seen as a form of doing nothing, but rather as activity, as a time filled with a range of different behaviors and emotional reactions, shaped by the changing conditions in which people adapt to liv?, creating new practices and routines in the process, while digital technologies are considered integral and equal elements of social connections and worlds, as well as active and intertwined components of everyday life. This work is based on part of the material collected during field research conducted for the purpose of writing a doctoral dissertation.

Predicting Road Condition using Linear Hierarchical Modelling

Roads are vital elements of societal connectivity, facilitating the seamless flow of goods and people. Increased use of roads because of population growth and urbanization, combined with increased intensity and frequency of extreme events due to climate change have been accelerating road pavement deterioration. This leads to a cascade of adverse consequences, increasing safety risks, traffic congestion, and maintenance costs. Predictive maintenance can reduce failure risks, optimize resource allocation, and extend road lifespan, but it requires accurate deterioration models. Presented herein is an application of linear hierarchical modeling for predicting road condition. Hierarchical modelling is a state-of-the-art technique in industrial health management for data representing a population. The proposed method quantifies the uncertainty of prediction and considers the heterogeneity across different subpopulations of pavements caused by different design, traffic and environmental conditions. The results suggest that this technique can be effectively used for avoiding high variance caused by sparse health inspection data for some of the road sections. This method has the potential to significantly contribute to enhance asset predictive maintenance and consequently to operation and safety of roads and other infrastructure assets.

Histological and morphological development of the prepuce from birth to prepubertal age.

To study the histological changes of the preputial tissue from birth to prepubertal age in order to define unnoticed morphological changes. Prepuce samples were obtained from 79 healthy boys who underwent routine ritual circumcision. Specimens were divided into six groups according to the boys' age: newborn, 0-1 year of age, 2-3 years of age, 4-5 years of age, 6-7 years of age, and 8-9 years of age. Histologic analysis of the specimens was performed by H&E, Masson's trichrome, Verhoeff-Von Gieson, immunohistochemical staining. Microscopic examinations showed that average epithelial thickness increased after the neonatal period (p=0.001). When collagen fiber density was evaluated, no significant differences between groups were found (p=0.083). When the elastic fibers in the dermis were evaluated, it was determined that the number and thickness of elastic fibers increased with age. Immunohistochemical examinations showed that the number of peripheral nerves marked with S100 was lower in the neonatal period than at other ages (p=0.048). When the vessels marked with CD105 antibody were counted, there was no significant difference between the groups (p=0.078). This is the first study to examine the age-related structure of connective tissue elements in the foreskin. Our results showed that the prepuce's prepubertal maturation process is continuous, and the first 2 years of life are appropriate not only in relation to the physiological effects of age but also the optimum structural changes for wound healing, such as vessel diameter, epithelium thickness, peripheral nerve count.

Актуализация методики прогнозирования финансовой устойчивости с учётом ликвидационной стоимости основных средств

The article is devoted to the development of scientific and methodological foundations of economic analysis and theoretical basis formation of its modern direction. Formation of methods that take into account innovative development of accounting support is an urgent methodological task, which is important for scientific substantiation of instrumental and analytical base of tactical and strategic forecasting in order to obtain the necessary effect at all stages of economic entity development. The purpose of the study is to update economic analysis methodology and financial stability forecasting in the context of changing accounting legislation. The set of applied methods includes the following: general scientific research methods (monographic, materials generalization, and system research) and special methods of economic science (comparison, analysis, synthesis, and modeling). The article assesses the changes in fixed assets accounting, which are introduced by the Federal Accounting Standard 6/2020 "Fixed assets". The analytical value of this document, connected with liquidating value accounting of fixed assets, is proved. It can have a significant impact on relevant cash flows when assessing the level of financial stability. The interrelation of cost indicators forming the book value and expenditure component (loss-making) of fixed assets and cash flows in the context of accounting (financial) reporting forms is determined. The model of analytical tools to control fixed assets in forecasting financial stability is substantiated, the construction of which is based on the connecting elements of the balance sheet characterizing the type and level of financial stability.

Assessment of the load-loading capacity of bolted joints during bolt bending and the combination of materials used

Abstract: based on the physical model of a hinged-bolt joint, which takes into account the possible bending of the bolt and, consequently, the real nature of the distribution of contact loads, the influence of the main design parameters of the joints on the distribution of loads between individual elements depending on the combination of their materials is analyzed. Dependencies for determining normal stresses in a given section of a connection element are presented, variants of the structural and technological design of typical hinge-bolt connections are analyzed according to the degree of influence of their geometric and material science features on the level of contact loads.

Uticaj vrste elementa veze i lepka na cvrstocu ugaonih spojeva kod prozora: Deo 1

In the article, the effect of the surface on the strength of the corner joint on the window was analyzed. The corner joint on the window is made in the variant with double and triple dowel and slot using PVaC adhesive. Samples were made from pine tree (Pinus Nigra). For research purposes, a special holder was made for the samples to enable testing according to the EN514:2018 standard method. The aim of the work is to determine the influence of the connection element on the strength of the corner joint of the window when using PVaC glue. The samples were divided into 2 groups of 30 samples each, depending on the number of dowels. The standard methods of statistical analysis were used. The test showed that the connection with triple dowel and slot has higher breaking strength values compared to double dowel and slot.

Histological demonstration of changes in connective tissue components in uterine tissue undergoing decidualization on days 4th, 5th, and 8th days of mouse pregnancy

This study examined the changes in connective tissue elements of the uterine undergoing decidualization on the 4th, 5th, and 8th days of pregnancy by histochemical methods. The study divided 6-8 weeks-old Balb/c mice into four groups non-pregnant estrous phase, 4th, 5th, and 8th-day pregnancy models. 5µm thick sections were taken from paraffin blocks obtained from uterine tissues. Samples were stained with Hematoxylin&Eosin, Mallory Azan, Orsein, and Periodic Acid Schiff stains. As a result of the staining, the uterine tissue in the non-pregnant estrus phase showed standard histological structure. On the 4th day of pregnancy, the amount of intensely stained collagen and elastic fiber decreased on the 5th day of gestation; On the 8th day of pregnancy, it was determined that the density of the fibers increased again. As a result, both increased collagen and elastic fibers for its placement to an elastic-solid uterine tissue and increased carbohydrates for its nutrient needs and immune privilege were demonstrated in the uterus for the 4th-day embryo. The decrease in connective tissue elements with the acceleration of decidualization on the 5th and increased collagen and elastic fibers in the myometrium and the PAS + NK cells in the endometrium on the 8th-day was noted.