Point Of Attachment Research Articles

Synthesis, (bio)degradation, and utilization of starch-derived biopolymers in defined hard waters

Climate change is causing a change in local rainfall, which generally brings with it a reduction in rainfall and, consequently, an increase in water hardness. This study explores the suitability and stability of various dextrin-derived polymers for cation removal in simulated hard water conditions. Thermal analysis and Fourier-transform infrared spectroscopy confirm the polymers' thermal stability and proper formation. Biodegradability assessments reveal KLEPTOSE®LINECAPS (LC) and GLUCIDEX2® (Glu2) dextrin with pyromellitic dianhydride (PMDA) derivatives have higher durability as they were able to endure enzymatic activity. Adsorption experiments at 300 and 600 ppm indicate significant variations influenced by monomer and crosslinker types, with linear monomers demonstrating superior performance. Notably, different crosslinkers exhibit varying affinities for calcium and magnesium ions, with PMDA derivatives excelling for magnesium and citric acid (CA) derivatives for calcium. Kinetic and isotherm studies reveal a favorable trend towards quasi-second-order kinetics and Freundlich isotherm models, attributed to cavity heterogeneity and diverse attachment points as evidenced in existing literature. These findings suggest promising applications for these polymers, traditionally employed for organic contaminant removal, as additional filters to mitigate water hardness.

Calcineurin-fusion facilitates cryo-EM structure determination of a Family A GPCR

Advances in singe-particle cryo-electron microscopy (cryo-EM) have made it possible to solve the structures of numerous Family A and Family B G protein-coupled receptors (GPCRs) in complex with G proteins and arrestins, as well as several Family C GPCRs. Determination of these structures has been facilitated by the presence of large extramembrane components (such as G protein, arrestin, or Venus flytrap domains) in these complexes that aid in particle alignment during the processing of the cryo-EM data. In contrast, determination of the inactive state structure of Family A GPCRs is more challenging due to the relatively small size of the seven transmembrane domain (7TM) and to the surrounding detergent micelle that, in the absence of other features, make particle alignment impossible. Here, we describe an alternative protein engineering strategy where the heterodimeric protein calcineurin is fused to a GPCR by three points of attachment, the cytoplasmic ends of TM5, TM6, and TM7. This three-point attachment provides a more rigid link with the GPCR transmembrane domain that facilitates particle alignment during data processing, allowing us to determine the structures of the β2 adrenergic receptor (β2AR) in the apo, antagonist-bound, and agonist-bound states. We expect that this fusion strategy may have broad application in cryo-EM structural determination of other Family A GPCRs.

Intrinsic characteristics of three-dimensional flow around a wall-mounted conical cylinder

To investigate the flow characteristics around a wall-mounted conical cylinder, three-dimensional direct numerical simulations are carried out for a conical cylinder with an end diameter ratio ranging from 0.5 to 1.5 at three low Reynolds numbers (Re = 100, 150, 200). The flow features are examined in terms of time-mean streamlines, singularity points location, topological structure, time-mean streamwise vortices, and instantaneous spanwise vortices denoted with different vortex identification methods. The downwash effect also happens even without a free end. The upwash streamlines clash with the downwash streamlines and then coalesce to the saddle (impingement) point P2. The occurrence of the symmetry plane belongs to a new topology, where the saddle point on the bottom wall is an attachment point (NA), instead of the separation point (SS). The singular point verifies the topological existence of the attachment–attachment combination of the horseshoe vortex system. The “Quadrupole Type,” “Sextupole Type,” and “Octupole Type” are identified. The “Octupole Type” is reported first, consisting of a pair of “time-mean streamwise tip vortices,” two pairs of “time-mean streamwise base vortices” and a pair of “time-mean streamwise bottom vortices.” Moreover, the vorticity magnitude cannot represent the occurrence of vortices. The instantaneous iso-surfaces of Q = 0.2 and λ2 = –0.2 in the wake are similar to the threshold of Ω = 0.52. In contrast, the Liutex/Rortex method is easier to identify the streamwise bottom vortices than the former two methods.

КОМП'ЮТЕРНИЙ МОДУЛЬ ДЛЯ АНІМАЦІЇ РУХУ ШАТУННО-ПОВЗУНКОВОЇ ГРУПИ ПРОГРАМИ KDAM ПРИ ВИЗНАЧЕННЯ КІНЕМАТИЧНИХ ТА ДИНАМІЧНИХ ПАРАМЕТРІВ

The development of new schemes of the thread feeding system requires an operational assessment of the value of the tension in front of the working zone. The objective function in the tasks of optimizing technological processes is the minimum necessary tension. The development of special computer programs for determining the tension in the working area makes it possible to determine the necessary technological parameters. The variable parameter in the objective function is the sum of the angles of coverage of the working bodies by the thread. The use of a computer program allows you to determine the tension and change in relative tension in the filling zones of technological machines, which allows you to optimize the shape of the thread supply line even at the stage of designing the technological process. A computer module was developed for the animation of the movement of the connecting rod-slider group, which is a component of the KDAM program for determining the kinematic and dynamic parameters of the connecting rod-slider group of the mechanisms of textile and light industry machines, which allows at the preliminary design stage to visually evaluate the behavior of individual links of the connecting rod mechanism of the slider group and determine the coordinates, projections of velocities and accelerations of the center of mass of the connecting rod, the slider and the points of attachment of the links of the Asura groups on the connecting rod. The KDAM program is a structural element of a computer software complex for assessing the intensity of technological processes in the light and textile industry when determining the change in the relative tension of the thread in the filling zones on the technological equipment. Kinematic and dynamic analysis of flat mechanisms plays a significant role in the design of new mechanisms and modernization of existing ones. The results obtained during these studies can be used to calculate the strength of individual links, their inertial characteristics, optimization of structural parameters of mechanisms, and minimization of consumed energy. The computer module of the KDAM program for determining the kinematic and dynamic parameters of the connecting rod-slider group of mechanisms of light industry machines allows you to determine the coordinates, projections of velocities and accelerations of the center of mass of the connecting rod, slider and the point of attachment of the links of the Asura groups on the connecting rod. During the dynamic analysis of the operation of the connecting rod-slider group, the projections of the full reaction in the joints between the crank and the connecting rod, between the connecting rod and the slider, and between the slider and the fixed guide are determined.

Методика фотограмметричного вимірювання люфтів та пружних податли-востей в шарнірних вузлах транспортних маніпуляторів та штанг косміч-них апаратів

The experimental study on multi-link structures and their components is of extreme relevance and importance to modern science and technology. These structures are widely used in various fields, including the aerospace and the automotive industry, robotics, and construction. The presence of numerous interconnected components makes their behavior complex and nonlinear. The accuracy and reliability of such systems depend on their dynamic characteristics, which are difficult to predict theoretically due to numerous factors, such as the material compliance, hinge backlashes, and intercomponent interaction. This study presents the authors’ verified methodology for experimentally determining backlashes and elastic compliances in hinges of transport manipulators and spacecraft booms, which is based on the photogrammetric method. The versatility of the method as applied to different types of mechanical experiments was analyzed. The obtained measurement accuracy and applicability to various structures under heterogeneous conditions make the methodology substantially universal. The methodology was tried out using a two-link fragment of a transport manipulator designed by the authors. A computational scheme was constructed to determine the effect of a hinge backlash. The scheme was used to obtain rotation trajectories of the manipulator section for different backlash values. It was found that photogrammetry can be used to determine the trajectories of each control marker on the hinge throughout its operational time. This allows one to refine computational schemes with calculated backlash values. The proposed methodology can easily be adapted to studying the elastic compliance of multi-link structure components in local stiffness reduction zones, such as flange connections and auxiliaries-to-link attachment points. The measurement methodology may be used in studying the dynamics of multi-link and ultralong structures by synchronizing several digital cameras. This enables remote monitoring of moving structures in space.

A percolation-type criticality threshold controls immune protein coating of surfaces.

When a material enters the body, it is immediately attacked by hundreds of proteins, organized into complex networks of binding interactions and reactions. How do such complex systems interact with a material, "deciding" whether to attack? We focus on the "complement" system of ∼40 blood proteins that bind microbes, nanoparticles, and medical devices, initiating inflammation. We show a sharp threshold for complement activation upon varying a fundamental material parameter, the surface density of potential complement attachment points. This sharp threshold manifests at scales spanning single nanoparticles to macroscale pathologies, shown here for diverse engineered and living materials. Computational models show these behaviors arise from a minimal subnetwork of complement, manifesting percolation-type critical transitions in the complement response. This criticality switch explains the "decision" of a complex signaling network to interact with a material, and elucidates the evolution and engineering of materials interacting with the body.

Issues of Manufacturability of Roller Machines

Issues of maintenance of manufacture adaptability are considered in the article on an example of roller squeezing machines; recommendations to increase the manufacture adaptability of designs are offered. The geometry and kinematics of the attachment points of the base plate of a vertical-type squeezing roller machine are considered.

Effectiveness of Retraction 30 over Gross Stretch For Relieving Pectoralis Minor Tightness Among College Students

Background: The Pectoralis minor muscle originates from different 3 ribs and converges into one attachment point. Pectoralis minor shortening can contribute to many syndromes and impairments, especially at the shoulder. Some of them are impingement of the soft tissues, adhesive capsulitis etc. The prevalence of pectoralis minor tightness is very high in college-going students. The gross stretch is the stretching procedure that increases the length of the pectoralis minor muscle. This shoulder position produces tension in the muscle insertion in a posterior direction in conjunction with the scapular motion that is performed at flexion and elevation in the scapular plane, thereby lengthening the muscle. Retraction 30 is stretching with scapular retraction at 30 degrees of shoulder flexion; the flexion angle at 30 degrees can lengthen the muscle along the muscle fiber direction in the coronal plane. 30 degrees of flexion is considered to be more comfortable than a higher angle of flexion, as well as the angle is closest to the line of force Objectives of the study: To compare the effectiveness of gross stretch and retraction 30 in relieving pectoralis minor muscle tightness which can be co-operated in further treatment protocols. Study Design: Comparative Study Methodology: Two group pre–test–post–test design was used with purposive sampling. Selected subjects were allocated to two groups. Fourty subjects (20 males and 20 females) who fulfilled inclusion and exclusion criteria were recruited for the study. The independent variables are gross stretch and retraction 30 whereas the dependent variables were PMI (pectoralis minor index), pectoralis minor length test and Cervical Curvature. Result: This study results imply that retraction 30 is better when compared to gross stretch for correcting pectoralis minor tightness. Hence should be included as an inevitable part of stretching treatment. Practicing clinicians should continue to use evidence-based decisions when treating pectoralis minor tightness.

Re-investigation of Bowmanites laxus Halle, 1927, a sphenopsid fructification from the Permian of China

Halle (1927) described and illustrated sphenopsid plant remains from Permian strata (Shihottse Formation) in Shanxi Province, China in the early 1920s. He designated the particular stratigraphic sources as Plant Bearing Beds 14 and 31 and described Bowmanites laxus, n. sp. from the former and Bowmanites sp. from the latter. The illustrated specimens, as well as additional ones from both beds were borrowed from the Palaeobotanical Collections of the Swedish Museum of Natural History, Stockholm, Sweden and re-investigated in order to prepare, re-illustrate, describe, and compare the species. The preparations revealed that the leaves in both species have the same morphology in the strobili as well as in the sterile axes and are arranged in open, not laterally fused whorls. Each leaf is arcuate and upwardly turned, the lamina is narrow at the point of attachment，and gradually expanded to become bilaterally laciniate and medially elongated into a sharply pointed apex. The sporangiophore in both species is axillary to the subtending sporophyll, remains free, following the upward curve of the sporophyll, and terminally, bears two peltately suspended sporangia that are aligned parallel to the lamina of the sporophyll. A single lectotype is chosen from/among the lectotype suite previously defined by Hoskins and Cross (1943). A systematic classification of the species is proposed. The summary of revisions of other sphenopsid species as suggested by Hoskins and Cross (1943) is presented in relationship to their proposal to divide the species of Bowmanites into three Sections in one of which B. laxus is included.

Intrusion and retraction with an innovative crane spring

Today, one of the most common lines of treatment for gummy smiles is the use of temporary anchorage devices (TADs). One of the major issues with the TADs is the unpredictability of stability during treatment. Additional to the loosening of TAD, gingival tissue overgrowth, especially when placed above the attached gingiva, is a persistent issue. During the process of intrusion and retraction, the point of force attachment in relation to the center of resistance is of prime importance to achieve the correct and required vector of force. This, at most times, is not achievable with TADs due to the interference of the roots of teeth. Thus, an alternative to TADs with the convenience of placing the point of force attachment anywhere in the buccal vestibule is discussed here in. This article describes the design and action of an innovative spring (Crane spring) wherein the point of force attachment can be varied to suit the biomechanics apart from delivering light and continuous forces using looped mechanics. The spring is of a simple design and can be easily constructed. It is highly efficient with intrusion and retraction.

Diagnosis and Analysis of Vasa Previa Types With Flow HD Glass Body.

To explore the value of applying flow high definition (HD) glass body in prenatal diagnosis of vasa previa and to preliminarily discuss the types of vasa previa. Two-dimensional ultrasound, flow HD, and flow HD glass body were used to image the umbilical cord insertion site and placenta, observe the cervical internal os and surrounding areas, and retrospectively analyze cases of vasa previa. There were 15 cases of vasa previa, including 14 cases of singleton pregnancies and 1 case of twin pregnancy, with a total of 22 vasa previa, including 10 veins and 12 arteries. There was 1 case with 3 vessels, 5 cases with 2 vessels, and 9 cases with a single vessel. Among them, in 3 cases of vasa previa detected at 12, 14, and 24 weeks, respectively, the vasa previa were relocated to a normal position at 24, 29, and 35 weeks of gestation when re-examined. Routine 2-dimensional ultrasound examination in this group showed tubular or circular hypoechoic areas near the cervical internal os, but vasa previa could not be confirmed. Flow HD could display color blood flow at and near the cervical internal os in 15 cases, but it was difficult to continuously show the course and source of the blood vessels under the chorion. Flow HD glass body from multiple angles could display the relationship between 15 cases of 22 vasa previa and the placenta and cervix. Combined with color Doppler blood flow spectra, flow HD glass body could determine the types of vasa previa. Flow HD glass body imaging can clearly display vasa previa, showing their origin and the spatial relationship with the cervix and placenta in a 3-dimensional manner, displaying the course and attachment points of umbilical vessels under the chorion. It can observe the area of interest at any angle, and combined with color Doppler blood flow spectra, it can judge the vasa previa of the umbilical vein, providing a more definite imaging basis for clinical management.

Finite element analysis of the Fibula's contribution to lower extremity torsional stiffness

AimsThe purpose of this article is to investigate the effects of the fibula on the torsional stiffness of the lower limb. A comprehensive model of the lower limb was constructed, including the resected femur, patella, tibia, fibula, and foot, with tendons and ligaments. Two configurations were developed, with and without the presence of the fibula, to evaluate the resulting stress state and consequently determine the contribution of the fibula to the torsional stiffness of the lower limb. MethodsThe finite element method was used to analyse how the fibula affects the stress distribution in the lower extremity under body weight loading and torsional forces. A detailed three-dimensional solid model of the lower extremity with and without the fibula was constructed. Loading conditions were imposed simulating an axial compressive load of 700 N applied to the upper extremity of the resected femur and a torsional load of 6000 Nmm applied to the proximal femur, and a fixed constraint was imposed on the foot. ResultsRemoving the fibula results in an increase in stress on all the tendons and ligaments tested. The increases ranged from 4 % (patellar tendon) to 21 % (lateral retinaculum). This suggests that the fibula plays a significant role in the distribution of mechanical stress in the lower extremity. The most affected structures are the lateral retinaculum and the posterior cruciate ligament, both with a 21 % increase in stress, suggesting that these structures may compensate more for the absence of the fibula. ConclusionThe fibula plays a critical role in maintaining the structural integrity and biomechanical function of the lower extremity. It acts as a lateral strut, contributing to the stability of the ankle and knee by providing an attachment point for several muscles and ligaments that are essential for coordinating complex movements and providing stability during dynamic activities.

Boosting thermoelectric performance of molecular junction by utilizing edge branches and weak coupling

In this study, we investigated the thermoelectric properties of molecular junctions, created by trapping naphthacene (C18H12) and rubrene (C42H28) molecules between two graphene electrodes. It is found that the charge transport of naphthacene-based and rubrene-based graphene junctions is not sensitive to the introduction of edge side branches or the increase in molecular length and still maintains resonance transport at the Fermi level. Notably, the presence of pendant branches on the molecular trunk in rubrene-based graphene junctions leads to a suppression of phonon transport, attributed to multiple scattering at the branch attachment points or Fano resonance scattering. The phonon thermal conductance of the rubrene junctions can be reduced by nearly half compared to that of naphthalene junctions. Furthermore, the room-temperature figure of merit (ZT) is significantly enhanced from 0.2 to 1.1 upon constructing weak coupling junctions, representing an almost tenfold increase over covalent junctions. These findings mean that it is highly desirable to find a mechanism that can suppress the phonon thermal conductance of self-assembled molecular films, while preserving their power factor at optimal levels to obtain high-efficiency thermoelectric performance.

Modern view on predicting outcomes after fetoscopic laser coagulation of placental anastomoses in polyuria-oliguria syndrome (review)

The purpose of this literature review is to analyze the results of fetoscopic laser photocoagulation of placental anastomoses, obtained in various studies published in foreign and domestic medical publications in recent years.Materials and methods. The review included published data over the last 10 years. The literature search was conducted in Medline, Scopus, Web of Science, Google Scholar, PubMed, Wiley and Cochrane Library databases.Result. As a result of the analysis, the main ultrasound and fetoscopic markers influencing the outcome of the surgical treatment were determined: the location of the placenta on the anterior and posterior walls, the location of the umbilical cord attachment, the number of placental anastomoses; abnormal graphs of blood flow rates in the umbilical cord arteries; the distance between the attachment points of the umbilical cord; dissociated growth of the fetuses; the duration of gestation and the stage of severity of twin-to-twin transfusion syndrome, as measured with the R. Quintero staging system, at the time of the operation; the experience of the operating surgeons; and the duration of the operation.Conclusion. Analysis of the literature data has shown that these markers are extremely unreliable in predicting the chances of survival for one or both fetuses. Further study of ultra-sound and fetoscopy predictors of adverse outcome of laser photocoagulation of placental anastomoses will allow for a more balanced approach to the choice of surgical tactics and personalized consultations with patients.

The Physics and Mathematics of Ziplining

We study the kinematic and dynamic characteristics of body motion along an inclined hanging cable in the approximation of its masslessness and inextensibility. It is shown that in this case, the motion of the suspended body occurs along an inclined ellipse, the foci of which are the cable attachment points. Herewith, at any given moment, the net tension force of the cable is perpendicular to the instantaneous velocity of the body. Besides, the tension force is a dynamic characteristic of the cable and increases as the body descends along with the increase in the speed. There is also a sharp increase in the tension at the end of the trajectory, which is explained by a decrease in its radius of curvature.

Influence of Porosities of 3D Printed Titanium Implants on the Tensile Properties in a Rat Tendon Repair Model.

There is a desire in orthopaedics to have soft tissue, particularly tendon, grow into metallic implants. With the introduction of three-dimensional (3D) printed porous metal implants, we hypothesized that tendons could directly attach to the implants. However, the effects of the porous metal structure on tissue growth and penetration into the pores are unknown. Using a rat model, we investigated the effect of pore size on tendon repair fixation using 3D printed titanium implants. There were three experimental groups of eight Sprague Dawley rats (n = 24) plus control (n = 3). Implants had defined pore sizes of 400µm (n = 8), 700µm (n = 8), and 1000µm (n = 8). A defect was created in the Achilles tendon and the implant positioned between cut ends and secured with suture. Specimens were harvested at twelve weeks. Half the specimens underwent mechanical testing to assess tensile load to failure. The remaining specimens were fixed and processed for hard tissue histological analysis. The average load to failure was 72.6N for controls (SD 10.04), 29.95N for 400µm (SD 17.95), 55.08N for 700µm (SD 13.47), and 63.08N for 1000µm (SD 1.87). The load to failure was generally better in the larger pore sizes. The 700µm and 1000µm specimens performed similarly, while the 400µm showed significant differences vs control (p = 0.039), vs 1000µm (p = 0.010), and approached significance vs 700µm (p = 0.066). There was increasing ingrowth as pore size increased. Histology showed fibrous tendon tissue within and around the implants, with collagen fibers organized in bundles. Tendon repair utilizing implants with 700µm and 1000µm pores exhibited similar load to failure as controls. Using a defined pore structure at the attachment points of tendons to implants may allow predictable tendon ingrowth onto/into an implant at the time of revision arthroplasty.

Effects of Tear-Associated Scapula Shape on the Stabilizing Potential of Glenohumeral Muscles

Glenohumeral muscles stabilize the humerus by providing compressive forces directed into the glenoid or by resisting opposing forces from larger muscles like the deltoid. Scapula shape is correlated to rotator cuff tear likelihood and previous research found that tear-associated shapes shift the supraspinatus’ line-of-action (LOA) anteriorly, potentially inhibiting its stabilizing potential. We predicted that the tear-associated scapula shape would cause an anterior shift in all glenohumeral muscles’ LOA. We expanded previous finite element models and computational scripts to compute the stability ratios of the teres major, teres minor, infraspinatus, supraspinatus and subscapularis on tear-associated and non-tear control scapulas. We identified insertion and attachment points for each muscle and created respective straight muscle meshes in Matlab. Then, we wrapped those meshes around the scapula and humerus surfaces and simulated an arm-raising motion in the open-source modelling package, Artisynth. In Matlab, we computed the muscle LOAs and their anterior-posterior (AP) and superior-inferior (SI) stability ratios, which describe how muscles tend to pull on the humerus relative to the glenoid. We found that the mean AP stability ratios of all five glenohumeral muscles were higher in the tear-associated scapula shape compared to the control shape, indicating an anterior shift in the muscles’ LOA. Aside from the teres minor, all other muscles exhibited slightly larger SI ratios for the tear-associated scapula shape, indicating a shift superiorly in their LOA. The tear-associated scapula shape may impact certain glenohumeral muscles’ ability to stabilize the humerus, placing higher demand on posterior fibres, subscapularis and teres major to maintain anterior stability. These findings indicate a potential injury mechanism caused by scapula shape and may help to inform rotator cuff tear prevention and rehabilitation. This method can also be applied to in vivo measurements of shoulder motions and bones to provide precise, patient-specific information on rotator cuff stabilizing potential.

BLUE SABINO: Development of a BiLateral Upper-Limb Exoskeleton for Simultaneous Assessment of Biomechanical and Neuromuscular Output

Arm and hand function play a critical role in the successful completion of everyday tasks. Lost function due to neurological impairment impacts millions of lives worldwide. Despite improvements in the ability to assess and rehabilitate arm deficits, knowledge about underlying sources of impairment and related sequela remains limited. The comprehensive assessment of function requires the measurement of both biomechanics and neuromuscular contributors to performance during the completion of tasks that often use multiple joints and span three-dimensional workspaces. To our knowledge, the complexity of movement and diversity of measures required are beyond the capabilities of existing assessment systems. To bridge current gaps in assessment capability, a new exoskeleton instrument is developed with comprehensive bilateral assessment in mind. The development of the BiLateral Upper-limb Exoskeleton for Simultaneous Assessment of Biomechanical and Neuromuscular Output (BLUE SABINO) expands on prior iterations toward full-arm assessment during reach-and-grasp tasks through the development of a dual-arm and dual-hand system, with 9 active degrees of freedom per arm and 12 degrees of freedom (six active, six passive) per hand. Joints are powered by electric motors driven by a real-time control system with input from force and force/torque sensors located at all attachment points between the user and exoskeleton. Biosignals from electromyography and electroencephalography can be simultaneously measured to provide insight into neurological performance during unimanual or bimanual tasks involving arm reach and grasp. Design trade-offs achieve near-human performance in exoskeleton speed and strength, with positional measurement at the wrist having an error of less than 2 mm and supporting a range of motion approximately equivalent to the 50th-percentile human. The system adjustability in seat height, shoulder width, arm length, and orthosis width accommodate subjects from approximately the 5th-percentile female to the 95th-percentile male. Integration between precision actuation, human–robot-interaction force-torque sensing, and biosignal acquisition systems successfully provide the simultaneous measurement of human movement and neurological function. The bilateral design enables use with left- or right-side impairments as well as intra-subject performance comparisons. With the resulting instrument, the authors plan to investigate underlying neural and physiological correlates of arm function, impairment, learning, and recovery.

ANALYSIS OF THE CAUSES OF CYLINDER HEAD FAILURE OF INTERNAL COMBUSTION ENGINES

The problem of failure of the cylinder head of an internal combustion engine is considered. The factors influencing the reliability of the cylinder head over a given service life are analyzed. Among the areas that suffer the most are considered: partition between valves and between the valve and the nozzle, exhaust channels, attachment points, the plane of the surface that is in contact with the block. An analysis of existing works was carried out. Usually, the issue of reliability of a separate zone is solved, about which you can find many articles and patents. To date, there are no known works that comprehensively consider the problem of the reliability of all problem areas related to the cylinder head. This work describes the nature of the influence on the stressed state of the cylinder head from various factors: temperature loads, loads from the pressure of the working body in the cylinder, loads arising during fastening. Ways to solve problems with the reliability of individual elements exist and are being solved by many researchers, but the expediency of their implementation is ambiguous. Thus, improving heat removal from the hottest surfaces can lead to an increase in the share of influence from other factors. Solving the problem of reliability requires comprehensive consideration and a comprehensive approach. Thus, when modernizing or developing a new design, it becomes mandatory to carry out a calculation study taking into account the most complete range of factors affecting the system, which combines all the constituent elements included in this node. Modern engineering analysis systems allow such studies to be performed. It is also important to have sufficient knowledge about the properties of materials, which significantly affects the quality of the results of calculation studies. The change in heat dissipation parameters over time can be taken into account with the help of boundary conditions, which will allow us to study how the cylinder head will behave after some time of operation.

Morphometric and anatomic characteristics of pronator quadratus muscle

PurposeIn surgical procedures commonly employed for the management of scaphoid and distal radial fractures, the incision and dissection of the pronator quadratus muscle play a pivotal role. Nevertheless, comprehensive investigations into the anatomical intricacies of the pronator quadratus muscle have been relatively scarce within the clinical community. In light of this, our study endeavors to make a substantive contribution to the medical literature by conducting a meticulous examination of the morphology and morphometry of this muscle. MethodsThis study is a cross-sectional observational study conducted on 22 cadaveric upper extremities (44 sides) preserved between January 2005 and December 2018 at Istanbul University. The study included specimens with intact dissection areas and no prior surgical intervention. Observations focused on the morphometry of the pronator quadratus muscle and related anatomical structures. Statistical analysis was performed using SPSS v23.0, employing Student's t-test and paired t-test, with significance set at p < 0.05. ResultsSignificant differences were found in the morphometric measurements of the pronator quadratus muscle between the right and left upper extremities, particularly in the vertical distance between the proximal and distal attachment points of the pronator quadratus to the radius (p = 0.008). Additionally, significant differences were observed between male and female samples for radius length (p < 0.001), ulna length (p < 0.001), pronator quadratus width (p < 0.001), and the vertical distance between pronator quadratus attachment points on both the radius (p = 0.001) and ulna (p = 0.001). Furthermore, significant correlations were identified between radius length and parameters such as the vertical distance between pronator quadratus attachment points on both the radius (p = 0.002) and pronator quadratus width (p = 0.03), and between ulna length and parameters including the vertical distances on the radius (p = 0.001) and ulna (p = 0.024). ConclusionIn light of our comprehensive analysis, which encompasses not only the anatomical features of the pronator quadratus muscle but also its vascular supply and the organization of its neurovascular structures, we posit that our study holds significant implications for the field of orthopedic surgery. We anticipate that this research will furnish valuable insights that can inform and enhance orthopedic procedures.