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The endothelial cells of the blood circulation are exposed to hemodynamic forces, such as cyclic strain, hydrostatic forces, and shear stress caused by the blood fluid's frictional force. Endothelial cells perceive mechanical forces via mechanosensors and thus elicit physiological reactions such as alterations in vessel width. The mechanosensors considered comprise ion channels, structures linked to the plasma membrane, cytoskeletal spectrin scaffold, mechanoreceptors, and junctional proteins. This review focuses on endothelial mechanosensors and how they alter the vascular functions of endothelial cells. The current state of knowledge on the dysregulation of endothelial mechanosensitivity in disease is briefly presented. The interplay in mechanical perception between endothelial cells and vascular smooth muscle cells is briefly outlined. Finally, future research avenues are highlighted, which are necessary to overcome existing limitations. [ABSTRACT FROM AUTHOR]

This activity gives students the opportunity to design an experiment, collect data, and solve for the spring constant of different springs. The use of low-cost materials and the inquiry-based structure makes it more accessible for teachers and more engaging for students. It can be scaffolded in several different ways, so that each teacher can differentiate according to the needs of their physics students. Some common student misconceptions are also addressed to assist teachers in their preparation for leading this activity. [ABSTRACT FROM AUTHOR]

Introduction. Deformations in bolted joints of elements in theoretical studies were taken into account by introducing linear deformation modules of elements instead of elasticity modules. The necessity to take into account the deformability of the interfaces is due to the fact that rigid nodes of rod structures are actually deformable, while hinged ones are able to perceive moments. The pliability of bolted joints leads to increase in the total deformations of structural structures by 40 % and change in the forces in the elements by up to 30 %. In some cases, the forces in the elements change the sign.Materials and methods. The experiment was carried out with the assistance of Bridge Crew No. 81 on a full-scale design of an auxiliary support for the semi-mounted assembly of the bridge span structure, coordinated with the Central Research Institute and Glavmoststroy. The vertical load on the support was created by the weight of the bridge superstructure being mounted, the horizontal load was created using a cable attached to a C-100 bulldozer tractor. Cable tension control with a bulldozer was performed with a dynamometer. Relative deformations were measured using beacons drilled into the body of the elements using a strainmeter with a base of 505 mm and a division price of 0.01 mm. The displacements in the bolted joints of the elements were measured with a strainmeter with a base of 125 mm.Results. The experimental force values obtained in the presence of displacements in the joints of the auxiliary support are quite close to the calculation results according to the proposed method. The average value of the ratio of experimental forces in the elements, taking into account displacements in the joints, to the values of theoretical forces without displacements (according to the hinge scheme) and to the values of theoretical forces, taking into account displacements in bolted joints, according to the proposed methodology, are 0.84 and 1.05, respectively. The average relative change in forces caused by displacements in the joints of the elements is 48 % for braces and 18 % for racks.Conclusions. It is shown that the experimental values of the forces in the elements are close to their calculated values determined by the calculated modules of linear deformation. At the same time, the magnitude of the forces differs significantly from their values obtained by calculation without taking into account the displacements in the elements.

The article presents the results of numerical simulation of the technological parameters of the process of milling polycarbonate workpieces at different combinations of cutter tooth spacing, cutting depth, and cutting speed with and without using ultrasonic vibrations. The influence of cutter tooth spacing and milling mode features on the technological parameters of the process, including friction and cutting forces and temperature, is established. Using ultrasonic vibrations achieves a decrease in the main component of the cutting force and in the average and maximum temperatures in the chip-tooth and tooth-workpiece contact areas. [ABSTRACT FROM AUTHOR]

The endothelial cells of the blood circulation are exposed to hemodynamic forces, such as cyclic strain, hydrostatic forces, and shear stress caused by the blood fluid’s frictional force. Endothelial cells perceive mechanical forces via mechanosensors and thus elicit physiological reactions such as alterations in vessel width. The mechanosensors considered comprise ion channels, structures linked to the plasma membrane, cytoskeletal spectrin scaffold, mechanoreceptors, and junctional proteins. This review focuses on endothelial mechanosensors and how they alter the vascular functions of endothelial cells. The current state of knowledge on the dysregulation of endothelial mechanosensitivity in disease is briefly presented. The interplay in mechanical perception between endothelial cells and vascular smooth muscle cells is briefly outlined. Finally, future research avenues are highlighted, which are necessary to overcome existing limitations.

Advances in biomaterial science have allowed for unprecedented insight into the ability of material cues to influence stem cell function. These material approaches better recapitulate the microenvironment, providing a more realistic ex vivo model of the cell niche. However, recent advances in our ability to measure and manipulate niche properties in vivo have led to novel mechanobiological studies in model organisms. Thus, in this review, we will discuss the importance of material cues within the cell niche, highlight the key mechanotransduction pathways involved, and conclude with recent evidence that material cues regulate tissue function in vivo.

CBCT (cone beam computed tomography) is an imaging investigation that provides three-dimensional (3D) images of craniofacial structures. The purpose of this study is to determine the mechanical behavior of an orthodontic system where the lingual treatment technique was used in a 25-year-old female patient from whom a set of CBCT scans was used. CBCT images were processed through software programs such as Invesalius, Geomagic, and Solid Works, to create models containing virtual solids. These models were then imported into Ansys Workbench 2019 R3 (a finite element method software program) for successive simulations to generate displacement maps, deformations, stress distributions, and diagrams. We observed that in the lingual technique, the lowest force occurring on the maxillary teeth is at 1.1, while the highest force appears at 2.3. In the mandible, the lowest force occurs at 4.6, and the highest force at 3.1. The values of the forces and the results of the finite element method can represent a basis for the innovation of new orthodontic springs and also of bracket elements. Thus, by using new technologies, orthodontic practice can be significantly improved for the benefit of patients. Other virtual methods and techniques can be used in future studies, including the application of virtual reality for orthodontic diagnosis. [ABSTRACT FROM AUTHOR]

We sought to understand how leaflet forces change in response to annular dilation and leaflet tethering in single ventricle physiology. Explanted fetal bovine tricuspid valves were sutured onto image-derived annuli and ventricular mounts. Control valves (CV) were secured to a size-matched HLHS-type annulus and compared to: 1) normal tricuspid valves (NTV) secured to a size-matched saddle-shaped annulus, 2) HLHS-type annulus with leaflet tethering (LT), 3) HLHS-type annulus with annular dilation (DIL), or 5) a combined disease model with both dilation and tethering (DIS). The specimens were tested in a systemic heart simulator at various SVPs. Leaflet forces were measured using optical strain sensors sutured to each leaflet edge. Average force in the anterior leaflet was 43.2% lower in CV compared to NTV (p<0.001). LT resulted in a 6.6% increase in average forces on the anterior leaflet (p=0.04), 10.7% increase on the posterior leaflet (p=0.03), and 14.1% increase on the septal leaflet (p<0.001). In DIL, average septal leaflet forces increased relative to the control valves by 42.2% (p=0.01). In DIS, average leaflet forces increased by 54.8% in the anterior leaflet (p<0.001), 37.6% in the posterior leaflet (p=0.03), and 79.9% in the septal leaflet (p<0.001). The anterior leaflet experiences the highest forces in the normal tricuspid annulus under SVP conditions. Annular dilation resulted in an increase in forces on the septal leaflet and leaflet tethering resulted in an increase in forces across all 3 leaflets. Annular dilation and leaflet tethering combined resulted in the largest increase in leaflet forces across all 3 leaflets. [ABSTRACT FROM AUTHOR]

This research investigates the impact of the Problem-Based Learning (PBL) model on enhancing students' critical thinking abilities within civic education in third-grade classes at SDN Srewendari, Malang City. The study aims to assess the influence of the PBL approach on students' proficiency in analyzing facts, articulating reasons and arguments, drawing conclusions, and effectively presenting their findings. Employing a quasi-experimental design with Nonequivalent Groups Pretest-Posttest Control Group methodology, the research compares the average post-test scores of critical thinking skills between the experimental and control groups through a t-test. The study population comprises third-grade students from SDN Srewendari, Malang City, with the sample consisting of experimental class IIIa and control class IIIb. Data collection involves observation utilizing rating scale instruments and assessments comprising test or evaluation questions administered during class sessions. The analysis is conducted descriptively and quantitatively, employing a difference test with a confidence level exceeding 95%. Findings indicate a positive and statistically significant impact of the Problem-Based Learning model on students' critical thinking skills within civic education. [ABSTRACT FROM AUTHOR]

Engineering activities often emphasize the practices of engineers but can sometimes feel disconnected from content. This engineering design activity ties together multiple Next Generation Science Standards and explicitly addresses the nature of engineering. We help students connect to authentic engineering through an activity wherein students design a capsule to transport samples from the surface of Mars back to Earth for NASA. Through this process, students define criteria for a successful design by contemplating the role of rovers and then design capsules by drawing on their knowledge of forces, motion, and thermal energy transfer. Finally, students test their designs and evaluate whether they met the criteria they set. [ABSTRACT FROM AUTHOR]

How and when the forces are applied during neonatal intubation are currently unknown. This study investigated the pattern of the applied forces by using sensorized laryngoscopes during the intubation process in a neonatal manikin. Nine users of direct laryngoscope and nine users of straight-blade video laryngoscope were included in a neonatal manikin study. During each procedure, relevant forces were measured using a force epiglottis sensor that was placed on the distal surface of the blade. The pattern of the applied forces could be divided into three sections. With the direct laryngoscope, the first section showed either a quick rise of the force or a discontinuous rise with several peaks; after reaching the maximum force, there was a sort of plateau followed by a quick drop of the applied forces. With the video laryngoscope, the first section showed a quick rise of the force; after reaching the maximum force, there was an irregular and heterogeneous plateau, followed by heterogeneous decreases of the applied forces. Moreover, less forces were recorded when using the video laryngoscope. Conclusions: This neonatal manikin study identified three sections in the diagram of the forces applied during intubation, which likely mirrored the three main phases of intubation. Overall, the pattern of each section showed some differences in relation to the laryngoscope (direct or video) that was used during the procedure. These findings may provide useful insights for improving the understanding of the procedure. What is Known: • Neonatal intubation is a life-saving procedure that requires a skilled operator and may cause direct trauma to the tissues and precipitate adverse reactions. • Intubation with a videolaryngoscope requires less force than with a direct laryngoscope, but how and when the forces are applied during the whole neonatal intubation procedure are currently unknown. What is New: • Forces applied to the epiglottis during intubation can be divided into three sections: (i) an initial increase, (ii) a sort of plateau, and (iii) a decrease. • The pattern of each section shows some differences in relation to the laryngoscope (direct or videolaryngoscope) that is used during the procedure. [ABSTRACT FROM AUTHOR]

Background: This research has been conducted to assess the effect of orthodontic treatment on endodontically treated tooth. Materials and Methods: Overall, fifty subjects had been recruited. The participants received root canal therapy within 3 months as well as had an appointment for fixed orthodontic therapy. All candidates underwent an intraoral investigation. Radiographic evaluation as well as therapy planning were completed. Fixed orthodontic therapy had been initiated. All of the participants had been recalled. Endodontically restored teeth had been evaluated. All outcomes were assessed via Statistical Package for the Social Sciences (SPSS) software. Results: In this study, there were 25 males and 25 females. Pulp stones were seen in 15 subjects. Apical periodontitis was seen in nine subjects. Apical root resorption was seen in seven subjects, and enamel decalcification was seen in four subjects. Overall, 35 out of 50 subjects showed negative effects of orthodontic treatment on endodontically treated teeth. Conclusion: Excessive orthodontic force may result in increased pulp and peri-apical inflammation.

Annulus fibrosus (AF) plays a crucial role in the biomechanical loading of intervertebral disc (IVD). AF is difficult to self-heal when the annulus tears develop, because AF has a unique intricate structure and biologic milieu in vivo. Tissue engineering is promising for repairing AF rupture, but construction of suitable mechanical matching devices or scaffolds is still a grand challenge. To deeply know the varied forces involved in the movement of the native annulus is highly beneficial for designing biomimetic scaffolds to recreate the AF function. In this review, we overview six freedom degrees of forces and adhesion strength on AF tissue. Then, we summarize the mechanical modalities to simulate related forces on AF and to assess the characteristics of biomaterials. We finally outline some current advanced techniques to develop mechanically adaptable biomaterials for AF rupture repair.

Les recherches en psychologie positive suggèrent que certaines pratiques en psychothérapie engendrent des bénéfices cliniques importants, mais il n'est pas toujours clair pour les cliniciens quelles pratiques prioriser ou bien encore comment les intégrer en psychothérapie. Cette recherche vise à identifier et expliquer, pour les cliniciens, certaines pratiques cliniques à intégrer dans la pratique psychothérapeutique. Huit professionnels (incluant : professeurs-chercheurs, psychologues et étudiants au doctorat) se sont réunis durant six rencontres de deux heures afin d'identifier, classifier et décrire comment les résultats de recherches récentes pourraient informer les interventions auprès des clients. Ces conclusions ont subséquemment été spécifiées et bonifiées via une comparaison plus approfondie avec la littérature. Nous décrivons huit pratiques : (1) Évaluer également ce qui va bien chez les clients (2) Favoriser leur motivation autodéterminée ; (3) Mettre en valeur leurs forces et compétences ; (4) Mettre en lumière leur résilience ; (5) Favoriser l'autocompassion et la bienveillance ; (6) Favoriser le soutien et la cohésion sociale, notamment par la gratitude et la compassion ; (7) Favoriser le développement d'une mentalité de croissance ; et (8) Intégrer soi-même les principes qui favorisent le bien-être psychologique. Les cliniciens et leurs clients gagneraient à favoriser ces pratiques en psychothérapie. Research in positive psychology suggests that certain psychotherapy practices yield substantial clinical benefits, but it is not always clear to clinicians which practices to prioritize or how to integrate them into psychotherapy. This research aims to identify and explain, for clinicians, certain clinical practices to be integrated into psychotherapeutic practice. Eight professionals (including: professor-researchers, psychologists, and doctoral students) gathered during six two-hour meetings to identify, classify, and describe how the results of recent research could inform interventions with clients. These conclusions were subsequently specified and developed via a more in-depth comparison with the literature. We describe eight practices: (1) Also assess what is going well with clients (2) Foster their self-determined motivation; (3) Highlight their strengths and skills; (4) Highlight their resilience; (5) Promote self-compassion and loving-kindness; (6) Foster support and social cohesion through gratitude and compassion; (7) Foster the development of a growth mindset; and (8) Integrate, as a therapist, those same principles that promote psychological well-being. Clinicians and their clients would benefit from promoting these practices in psychotherapy. [ABSTRACT FROM AUTHOR]

Physical forces are ubiquitous in biological processes across scales and diverse contexts. This review highlights the significance of mechanical forces in nervous system development, homeostasis, and disease. We provide an overview of mechanical signals present in the nervous system and delve into mechanotransduction mechanisms translating these mechanical cues into biochemical signals. During development, mechanical cues regulate a plethora of processes, including cell proliferation, differentiation, migration, network formation, and cortex folding. Forces then continue exerting their influence on physiological processes, such as neuronal activity, glial cell function, and the interplay between these different cell types. Notably, changes in tissue mechanics manifest in neurodegenerative diseases and brain tumors, potentially offering new diagnostic and therapeutic target opportunities. Understanding the role of cellular forces and tissue mechanics in nervous system physiology and pathology adds a new facet to neurobiology, shedding new light on many processes that remain incompletely understood. Pillai and Franze provide a comprehensive overview of recent advancements in our understanding of how mechanical cues, e.g., tissue stiffness and cellular forces, contribute to nervous system development, homeostasis, and disorder. They illuminate experimental approaches, mechanotransduction pathways, and open questions. [ABSTRACT FROM AUTHOR]

This paper is concerned with the experimental investigation and mechanistic prediction of cutting forces for flat-end milling with tool runout. The effects of the tool geometry, the workpiece material and cutting parameters such as spindle speed, tool engagement and cutting direction are investigated. The mechanistic force model uses the trochoidal flute path to calculate the undeformed chip thickness. Average cutting force and linear regression model are applied for identifying the coefficients of the force model, and tool runout parameters are established from the radii of all flutes at the free end of the cutting tool. A series of milling processes are conducted on AZ31 Magnesium (Mg) alloy and titanium alloy (Ti6Al4V) to analyze the instantaneous cutting force curves, amplitudes of cutting forces and peak forces over a wide range of conventional spindle speeds, namely 600, 1200 and 3000 rev/min. It is found that the values of the cutting force coefficients are higher at lower spindle speed and decrease with an increase in spindle speed, especially when machining Ti6Al4V alloy. For the edge force coefficients, it is observed a slight variation when using cutting tools with different helix angles. Besides, the cutting force amplitudes strongly depend upon the workpiece material. The helix angle has a significant influence on the transverse force amplitude at the spindle speed of 600 rev/min. The cutting forces obtained mechanistically are also substantiated by comparison with measurements. [ABSTRACT FROM AUTHOR]

The present paper focuses on analyzing the occurrence of defects such as dents and local deformations by laboratory simulations of a real case of a defect detected on a natural gas distribution pipeline lain at a depth of approximately 0.6 m. The defect is caused by a river stone which due to the compression forces, damages the pipe to the point of cracking. In the laboratory, the simulation was carried out on a steel pipe insulated with extruded polyethylene which was acted upon by a mandrel made of duralumin. The purpose of the tests is to determine the maximum values at which the pipe material fractures. It was found that the fracture of the pipes when there are rigid bodies in the protective layer of sand is accelerated by the sand existing between them and the pipe and by the change in the properties of the steel the pipes are made of when they are kept in water. [ABSTRACT FROM AUTHOR]

Stamping of round hollow semi-finished products by hot reverse extrusion is one of the initial operations in the manufacture of hollow products for special purposes. The force and shape change of the metal during hot plastic forming is significantly affected by the deformation rate or the speed of movement of the deforming tool. For special-purpose products, certain mechanical properties are required in the wall height and bottom part. The wall height properties are ensured at subsequent stretching transitions with thinning of the semifinished product obtained by hot extrusion, which involves working out the metal structure by plastic deformation to achieve the required properties. Therefore, it is an urgent task to study the effect of the deformation rate on the force and shape change of the metal during hot reverse extrusion of hollow semi-finished products. To determine the influence of the deformation rate on the parameters of hot reverse extrusion with the dispensing of hollow semifinished products from round and square billets by means of finite element method (FEM) modeling and to compare the results of theoretical researches. Theoretical researches of extrusion power modes, specific forces, and the stress-strain state of metal were carried out by modeling using the FEM in the DEFORM software environment. The FEM was used to model the process of hot reverse extrusion with dispensing of round hollow semi-finished products from mild steel with protrusions at the end of the bottom part on the side of the cavity and on the outer surface. The deformation rate was in the range of 20 to 80 mm/sec. Round and square cross-sectional blanks were used. The dependence of the extrusion force on the punch displacement was determined. The distribution of specific forces on the deforming tool was determined. The stress-strain state and temperature distribution in the deformed metal at the end of extrusion were determined. The development of the metal structure by hot plastic deformation was evaluated and the results obtained were compared The effect of the deformation rate on the parameters of hot reverse extrusion with dispensing of round hollow semi-finished products was determined. [ABSTRACT FROM AUTHOR]

To obtain a finite element algorithm in the three-field formulation, a conditional functional was used, based on the equality of the actual work of the internal force factors (internal forces and moments) at the strains and curvatures of the middle surface. As an addition, the functional assumed the condition that the work of the residual of internal forces at the strains and curvatures of the middle surface had been equal to zero. The difference between the adopted internal forces and the internal forces represented through the strains and curvatures of the middle surface according to Hooke's law was used as the residual of internal forces. A quadrilateral fragment of the middle surface of a thin shell was used as the finite element. Kinematic quantities (displacements and their first order derivatives), strain quantities (strains and curvatures of the middle surface) and force quantities (internal forces and moments) were taken as the nodal unknowns. Approximating expressions with Hermite polynomials of third degree were used to approximate kinematic quantities. The sought strain and force quantities were approximated through the corresponding nodal unknowns by bilinear shape functions. A finite element stiffness matrix (with the dimensions 36x36) with respect to the kinematic nodal unknowns was formed through the functional minimization. Specific examples showed the efficiency of the three-field finite element algorithm in determining the displacements, strains and internal forces.

Being one of the most functionally loaded systems, the human hand and its anatomical structures are damaged quite often. Thus, injuries to the interphalangeal joints account for up to 60 % of all hand injuries. Post-traumatic arthrosis, contractures with persistent pain syndrome, stiffness and ankylosis of the joints are distinguished among the consequences of hand joint injuries. With the development of the endoprosthesis method, the use of which allows to restore the lost function of the organs of the musculoskeletal system, new opportunities are opening up in the rehabilitation of patients with various injuries of the joints of the hand. However, when using this method, there are certain complications associated with the wear of the implant, the reaction of the surrounding tissues to the material from which the prosthesis is made, and the design features of endoprostheses. That is, the success of treatment when using endoprostheses depends to some extent on the design of the implant. It is possible to carry out a primary analysis of the effectiveness of the proposed design of the endoprosthesis with the help of specialized software complexes. Despite the power of specialized software, building digital models of biological objects and performing calculations is quite a difficult task. In order to carry out a numerical study, in addition to knowing of the geometry of objects and their mechanical properties, it is also necessary to understand the conditions of interaction between the model fragments and the loading scheme. Aim. Develop a technique for analytical determination of forces in the tendons of the fingers. Materials and methods. The research was carried out using the provisions and methods of theoretical mechanics and resistance of materials. As a calculation case, this paper proposes to consider the determination of forces in the tendons of the index finger of the right upper limb. Results. As a result of the performed calculations, analytical expressions were obtained to determine the forces that occur in the flexor tendons of the index finger. Conclusions. The obtained analytical expressions allow us to estimate the magnitude of forces that occur in the tendons of the fingers. The results of the calculations can be used in the construction of digital models of the fingers and perform numerical studies.

The present article describes a new and innovative method of producing an inseparable joint with the use of expansion jaws. The effect of jaw tool geometry on the reaction forces and ultimate strength of an inseparable joint formed on a prototype stand was analyzed. The results are also compared of joints produced by jaws with single movement method and with complex movement method. The tool responds with bending and pressing one part into the other, which results in their permanent connection. In the tests, differentiation was introduced with regard to the height of the applied force to the collar of the connection pipe. A novelty is also a solution based on a complex, parameterized trajectory of the stamp movement consisting of horizontal and vertical displacements. This paper presents the tests of the joints formed at the stand. The new approach described in this article has resulted in a joint strength increase of approximately 30% using the innovative complex jaw movement of the biaxial clinching process. A joint tensile strength close to 1000 N was achieved.

This study attempts to shed new light on the dynamics of a turning ship using the principles of free body diagrams (FBDs). Unexpectedly, the literature gap is defined by incomplete and flawed FBDs. The method behind this new approach involves the FBD of a turning ship, with all the essential forces included, namely propulsive force, sideward thruster force (producing the initial turning moment), drag force, lift force, centrifugal force, inertial force, and hydrodynamic force couple. From these forces, the force and moment equations are derived. The accelerations are calculated from the force and moment equilibria to simulate the dynamics from input parameters such as mass m, length L, draught D, and fluid density ρ. The turning dynamics are explained in terms of velocities, accelerations, forces, and moments, based on two conditions: flat and steep angles of attack (AoA) and long and short turning radii R. A critical result is the proportionality of lift and centrifugal forces, leading to the proposal of a pleometric index (m·L–2·D–1·ρ–1), which is nonlinearly proportional to the product of AoA and R/L, characterising the dynamics of a turning ship. The FBD approach of this study also identified missing databases required for accurate simulation of turning dynamics, such as drag and lift coefficients of different hull geometries.

Abstract Objective The objective of this study was to measure the forces and moments exerted by direct printed aligners (DPAs) with varying facial and lingual aligner surface thicknesses, in all three planes of space, during lingual movement of a maxillary central incisor. Materials and methods An in vitro experimental setup was used to quantify forces and moments experienced by a programmed tooth to be moved and by adjacent anchor teeth, during lingual movement of a maxillary central incisor. DPAs were directly 3D-printed with Tera Harz TC-85 (Graphy Inc., Seoul, South Korea) clear photocurable resin in 100-µm layers. Three multi-axis sensors were used to measure the moments and forces generated by 0.50 mm thick DPAs modified with labial and lingual surface thicknesses of 1.00 mm in selective locations. The sensors were connected to three maxillary incisors (the upper left central, the upper right central, and the upper left lateral incisors) during 0.50 mm of programmed lingual bodily movement of the upper left central incisor. Moment-to-force ratios were calculated for all three incisors. Aligners were benchtop tested in a temperature-controlled chamber at intra-oral temperature to simulate intra-oral conditions. Results The results showed that increased facial thickness of DPAs slightly reduced force levels on the upper left central incisor compared to DPAs of uniform thickness of 0.50 mm. Additionally, increasing the lingual thickness of adjacent teeth reduced force and moment side effects on the adjacent teeth. DPAs can produce moment-to-force ratios indicative of controlled tipping. Conclusions Targeted increases in thickness of direct 3D-printed aligners change the magnitude of forces and moments generated, albeit in complex patterns that are difficult to predict. The ability to vary labiolingual thicknesses of DPAs is promising to optimize the prescribed orthodontic movements while minimizing unwanted tooth movements, thereby increasing the predictability of tooth movements.

Measurement of forces and torques in flexible connection joints for parabolic trough collectors (PTC) during their life time is important to prevent damage or breakage of these elements. Plataforma Solar de Almería (PSA) has developed and patented a device for measuring these forces and torques in flexible connection joints installed in solar power plants. The device consists of three dynamometers and one torque transducer coupled to a rotation assembly that can be externally coupled to a ball joint installed in interconnections of parabolic-troughs, with no interference in the hydraulic circuit. To calibrate the device and perform initial performance checks at lab scale, a test bench was prepared for applying forces and torques on a set-up composed of a multicomponent sensor connected in series to a standard rotary ball joint and measuring simultaneously the forces and torques by mean of the designed device. Calibration tests have been performed applying a range of forces and torques to the multicomponent sensor-ball joint at different rotation positions. Multicomponent sensor and developed device measurements have been compared to obtain a calibration matrix for the last one. Results show good performance of the device once calibrated, but that will be improved measuring angular deviations from reference axes position of each of the dynamometers that compose the device during the operation, to increase the accuracy of the measurements.

Introduction: We study optimization methods for poses and movements of chained Stewart platforms (SPs) that we call an “Assembler” Robot. These chained SPs are parallel mechanisms that are stronger, stiffer, and more precise, on average, than their serial counterparts at the cost of a smaller range of motion. By linking these units in a series, their individual limitations are overcome while maintaining truss-like rigidity. This opens up potential uses in various applications, especially in complex space missions in conjunction with other robots. Methods: To enhance the efficiency and longevity of the Assembler Robot, we developed algorithms and optimization models. The main goal of these methodologies is to efficiently decide on favorable positions and movements that reduce force loads on the robot, consequently minimizing wear. Results: The optimized maneuvers of the interior plates of the Assembler result in more evenly distributed load forces through the legs of each constituent SP. This optimization allows for a larger workspace and a greater overall payload capacity. Our computations primarily focus on assemblers with four chained SPs. Discussion: Although our study primarily revolves around assemblers with four chained SPs, our methods are versatile and can be applied to an arbitrary number of SPs. Furthermore, these methodologies can be extended to general overactuated truss-like robot architectures. The Assembler, designed to function collaboratively with several other robots, holds promise for a variety of space missions. [ABSTRACT FROM AUTHOR]

The myth about special quantum mechanics, different from classical mechanics, has been debunked. In fact, there is a branch of classical mechanics, which belongs to wave theory and considers a particle-like wave, rather than a particle having the properties of a wave. New quantum mechanics, free from unnecessary entities, assumptions, and hypotheses, makes it possible to get rid of many accumulated contradictions in theoretical physics, physical chemistry, and quantum chemistry and expands the methodological base of engineering disciplines by opening up new ways and means for solving practical problems, as shown by the example of consideration of chemical bonding as a resonant-selective interaction. [ABSTRACT FROM AUTHOR]

The results of the study are aimed at developing a nonlinear strain model for reinforced concrete beam elements in the general case of force actions and temperature effects for different durations. As a rule, temperature effects on structures involve temperature drops, causing heterogeneity of mechanical and rheological properties of concrete and reinforcement. The article has approximating expressions needed to take into account the effects of temperature and heating time on the values of temperature-induced strain and mechanical and rheological properties of heavy concretes with C30–C60 strength classes. The properties of concrete and rebars are heterogeneous from top to bottom and across the width of the cross section. A physically nonlinear problem is solved using the method of elastic solutions combined with the method of stepwise increases in temperature and force loading. The cooling of a heated reinforced concrete element to normal temperature is considered a short-term effect. Strength criteria of portions of a concrete cross section, crack closure conditions, and the ability of cracked sections to take loads in compression amid a change in the sign of stresses are determined. The stress–strain state (SSS) analysis of reinforced concrete beams, made according to the proposed method, is compared with the experimental studies using (i) values of thermal bending moments in statically indeterminate structures, (ii) cracking forces, and (iii) values of deformations (elongations and curvatures) of the elements in the longitudinal axis. Good agreement between the calculated and experimental values of controllable criteria confirms the reliability of physical relationships (i) developed for heterogeneous reinforced concrete beam elements and (ii) applied to the complex cases of temperature and force effects. [ABSTRACT FROM AUTHOR]

Numerical studies on rocket pumps are computationally expensive and hence the secondary passages such as sidewall clearance gaps, wear ring gaps, axial balancing mechanism, coolant/lubricant paths, etc. in the pump are usually not considered. In this study, a liquid propellant pump with and without secondary passages are modelled and flow simulation results are compared to analyse the differences in cavitation, vortices and radial force predictions arising due to the presence/absence of the secondary flow passages. Single-phase and multiphase simulations are conducted for the design and two off-design points. It is predicted that the presence of secondary passages has a significant effect on the type of cavitation instability predicted and on the volume of cavity generated in the inducer due to which the radial forces generated also differ significantly. The presence of secondary passages predicted large fluctuations from the average radial forces generated by the inducer. These are not obtained if the leakages are not considered. This type of underprediction during the design phase might cause severe wear and tear in the bearings during actual operation. Thus, this study stresses the need for incorporating the secondary passages even at the design stages. This study also highlights the possibility of cavitation instability type manipulation using some means in the inducer which would be significant for cavitation control research in rocket pumps. [ABSTRACT FROM AUTHOR]

The article presents a compact and exhaustive interpretation of the foundations of energodynamics and shows that it significantly extends the horizons of natural science and opens new avenues to improve the scientific bases of chemical technology. [ABSTRACT FROM AUTHOR]

The present paper aims to study the behavior of tailor welded blanks subjected to a single point incremental forming (SPIF) process from an experimental point of view. This process was chosen to deform truncated cone shapes of AA1050 aluminum alloy with different thicknesses. A uniaxial tensile test was performed to determine the mechanical characteristics of the alloy. Initial experimental tests implicated the use of variable wall angle parts which were processed on unwelded sheet blanks for determination of the behavior of the material and the forming forces. Afterwards, the wolfram inert gas (WIG) welding technique was used for joining two sheet blanks with different thicknesses either through one pass on one side, or by one pass on both sides. The conclusion of this paper indicates that one-sided welded blanks cannot be deformed successfully without fracture. In case of two-sided welded blanks, the results showed that the desired depth of 25 mm can be reached successfully. In case of the SPIF process, if welded blanks must be deformed, then the suitable method is to weld the blanks on both sides. [ABSTRACT FROM AUTHOR]

The purpose of the work is to develop a model and a method for determining the stress-strain state of the tool for abrasive processing of materials as an orthotropic composite with an arbitrary number of regularly spaced discrete grains connected by a bond material under the condition of a thermal increase in the size of an arbitrary grain of the working surface. The work establishes the following. The extreme shear stresses of the bond material in the plane normal to the working surface of the tool are almost twice as small as the corresponding stresses in the plane parallel to the working surface of the tool. The thermal increase in grain size, in accordance with the Saint-Venant’s principle, locally disturbs the stress-strain state of the tool. The size of the zone of local disturbance caused by the thermal expansion of the grain in the direction of expansion depends on the mechanical properties of the components of the tool (moduli of elasticity for the tension of the grain material and for the shear of the bond material). In all directions, the size of the disturbance zones of the stress-strain state depends on the number of grains in the tool in directions orthogonal to the direction of the thermal change in grain size. The obtained results make it possible to comprehensively take into account the composite orthotropic construction, the mechanical properties of the components of the tool in which, due to thermal expansion, the size of the arbitrary grain of the working surface has increased. The linearity of the problem statement allows, by summing up the results for the changes in the sizes of individual, several arbitrarily located grains, and at an arbitrary heating temperature of the grains, to determine the total stress-strain state. The obtained dependencies, at the stage of development of the processing technology, allow us to quantitatively estimate the stress level in the tool, to predict the likely number of load cycles before failure, to influence the value of stresses by selecting materials at the stage of tool manufacturing, to choose cutting modes at the stage of technology development, how to increase the efficiency of using the abrasive tool processing

CBCT (cone beam computed tomography) is an imaging investigation that provides three-dimensional (3D) images of craniofacial structures. The purpose of this study is to determine the mechanical behavior of an orthodontic system where the lingual treatment technique was used in a 25-year-old female patient from whom a set of CBCT scans was used. CBCT images were processed through software programs such as Invesalius, Geomagic, and Solid Works, to create models containing virtual solids. These models were then imported into Ansys Workbench 2019 R3 (a finite element method software program) for successive simulations to generate displacement maps, deformations, stress distributions, and diagrams. We observed that in the lingual technique, the lowest force occurring on the maxillary teeth is at 1.1, while the highest force appears at 2.3. In the mandible, the lowest force occurs at 4.6, and the highest force at 3.1. The values of the forces and the results of the finite element method can represent a basis for the innovation of new orthodontic springs and also of bracket elements. Thus, by using new technologies, orthodontic practice can be significantly improved for the benefit of patients. Other virtual methods and techniques can be used in future studies, including the application of virtual reality for orthodontic diagnosis.

Single Point Incremental Forming (SPIF) is an emerging materials processing technology. Owing to a number of merits, like reduced tooling, cycle time and cost and ability to produce sculptured profiles, in comparison to the traditional methods, the recent past has witnessed a growing interest in the application of SPIF to composite materials. This article authoritatively reviews the advancements in this area made since 2008. The review covers several aspects of the process including deformation characteristics, forming limits, failure modes forming forces, strain recovery, surface quality and analytical models. The current state of the technology and challenges are revealed, and many valuable findings are identified thereby setting guidelines for the process users. [ABSTRACT FROM AUTHOR]

Women's wartime sexual violence experiences have largely been constructed as negative, leaving little room for women's resistance and strength-based outcomes. Using Interpretative Phenomenological Analysis, this study examines women's resistance using semi-structured interviews with 13 ethnically diverse women victimized by sexual violence during the war in Bosnia and Herzegovina. Using partial results from the study highlighting strengths that are both external and internal to the women, I show that women resist traditional discourses of victimization and gender stereotypes as they speak about the strengths they have acquired and retained after they were sexually victimized. [ABSTRACT FROM AUTHOR]

In this study, the machinability of test pieces obtained from two different white cast irons, NiHARD-4 and HCWCI, were investigated by boring method, a machining process. The impacts of cutting parameters on cutting forces were identified. Analysis of variance was used to determine the effect ratios of the cutting parameters. Moreover, Taguchi analyses were used in the experiments to examine the impacts of cutting parameters on cutting forces. Considering the results in terms of dry and wet test conditions, it has been revealed that the cutting forces such as Fc, Fr and Ff of HCWCI material are lower than NiHARD-4 material in all test conditions. In dry cutting, high cutting speed and low feed have decreased the cutting forces. In wet cutting when the cutting speed has increased, Fr and Ff have increased. In terms of the cutting parameters, it was found that the most impact parameter on Fc is feed rate, the most impact parameter on Fr is material and the most impact parameter on Ff is cutting speed in dry cutting. In wet cutting, the most effective factor on Fc is feed rate, whereas the most effective factor on Fr and Ff is the material. Consequently, it can be said that to lower the cutting forces is required to reduce the feed rate and raise the cutting speed when NiHARD-4 and HCWCI materials are machined by boring operations with CBN inserts. [ABSTRACT FROM AUTHOR]

The present article describes a new and innovative method of producing an inseparable joint with the use of expansion jaws. The effect of jaw tool geometry on the reaction forces and ultimate strength of an inseparable joint formed on a prototype stand was analyzed. The results are also compared of joints produced by jaws with single movement method and with complex movement method. The tool responds with bending and pressing one part into the other, which results in their permanent connection. In the tests, differentiation was introduced with regard to the height of the applied force to the collar of the connection pipe. A novelty is also a solution based on a complex, parameterized trajectory of the stamp movement consisting of horizontal and vertical displacements. This paper presents the tests of the joints formed at the stand. The new approach described in this article has resulted in a joint strength increase of approximately 30% using the innovative complex jaw movement of the biaxial clinching process. A joint tensile strength close to 1000 N was achieved. [ABSTRACT FROM AUTHOR]