Terms Of Rigidity Research Articles

Dynamic characteristics of the tip leakage vortex in an oil–gas multiphase pump based on vorticity decomposition theory

AbstractThe paper combines experimental and numerical simulation methods to investigate the tip leakage vortex (TLV) in an oil–gas multiphase pump. The study aims to understand the evolution and dynamic characteristics of the TLV. The vorticity decomposition theory is used to analyze the spatial–temporal evolution, transient behavior, and rigid vorticity of the TLV. The findings reveal that the TLV is formed near the pressure surface when the tip clearance jet passes through the shear layer. In one impeller rotation period, transient fluctuations of the TLV are attributed to pressure differences and velocity changes across the tip clearance, and the TLV undergoes two split–dissipation–recurrence processes within one impeller rotation cycle. The presence of the gas phase enhances the scale and strength of the TLV while prolonging its existence in the flow channel. Analysis based on the rigid vorticity transport equation shows that the growth of the TLV and collapse are primarily governed by the rigid vortex generation term. The Coriolis force term contributes to stabilizing the TLV, while the rigid vorticity stretching term affects its shape. Furthermore, the gas phase significantly increases the value of the Rigid vorticity Curl of pseudo‐Lamb vector Term (RCT), which plays a crucial role in the prolonged existence of the TLV under gas–liquid two‐phase conditions. From an inlet gas void fraction of 0%–20%, the RCT value increases by 4.8 × 106/s2, the entropy production value increases by 75.55%, and the hydraulic efficiency decreases by 16.29%.

A Volterra edge dislocation problem in second-order elasticity theory

A displacement function technique has been developed to study plane strain problems in second-order elasticity theory for incompressible elastic materials. The formulation culminates in the development of a single inhomogeneous biharmonic equation of the form [Formula: see text] for the second-order displacement function [Formula: see text]. In the second-order, the isotropic stress associated with constitutive behaviour is governed by an inhomogeneous harmonic equation of the form [Formula: see text]. Both functions [Formula: see text] and [Formula: see text] depend only on the solution to the analogous problem in classical elasticity. While there are similarities to the Airy stress function, the displacement function approach enables the evaluation of the first- and second-order displacement fields purely through its derivatives, thus eliminating the introduction of arbitrary rigid body terms normally associated with formulations where the strains derived from a stress function approach need to be integrated. The displacement function approach is applied to develop a second-order elasticity solution to the problem of a Volterra edge dislocation.

FABRICACIÓN ADITIVA DE FÓRCEPS CON FIBRA DE CARBONO CONTINUA PARA EL ENTRENAMIENTO VIRTUAL DEL PARTO

Vaginal delivery assisted with forceps (FAVD) is an obstetric technique that involves the extraction of the fetus by traction and/or expansion of the birth canal with an instrument. Currently, the use of forceps allows for the resolution of pathological situations that would otherwise require a cesarean section with the risks of morbidity and mortality that this surgery entails. For this reason, there is a growing interest in increasing the percentage of FAVD, after obstetricians feel more confident after practicing in simulation workshops with mannequins and acquiring the necessary competencies for their correct use. The forceps is an instrument that requires a precise introduction and placement, so an electromagnetic tracking tool has been developed that knows, with high precision, the position of the instrument both inside the vagina and around the fetal head. With this, childbirth training is complemented by a virtual simulation, in real-time, that allows the internal position of the forceps to be seen, thus facilitating the learning and improvement of the introduction and placement technique. For this, the instrument must not contain any ferrous residue that interferes electromagnetically, so commercial forceps (made of stainless steel) are not valid. In this context, the reproduction of forceps has been proposed through additive manufacturing based on material extrusion (MEX). To obtain forceps that are as realistic as possible in terms of rigidity compared to commercial models, a nylon filament reinforced with carbon microfibers (Onyx) has been used to which continuous carbon fiber is added in successive layers. Given the limitations in the printing volume of the technology used (Mark Two), numerical simulations were carried out by finite element analysis and different proposals for dividing each piece and subsequent union by adhesives were made, finally developing the final solution. Keywords: additive manufacturing; carbon fiber extrusion; vaginal delivery forceps; medical training; electromagnetic tracking.

Real-time application of a dynamic disturbance suppression control approach for an axial active magnetic bearing system

Active Magnetic Bearings (AMBs) use magnetic forces to suspend the rotor, allowing contactless operation and the ability to adjust stiffness and damping. However, compared to mechanical bearings, magnetic bearings are much weaker in terms of rigidity. A large external force can lead to rotor/stator collision. This study proposes a Dynamic Stiffness Controller (DSC) for AMBs. The DSC dynamically adjusts the AMB stiffness to counter external disturbance forces in real-time. Experimental results show the effective change of AMB stiffness by DSC based on the magnitude of the external load. Furthermore, not only the AMB stiffness can be real-time adjusted to counterbalance disturbances but the steady-state energy consumption is improved as there is little disturbances applied to the system. The AMB-DSC system exhibiting only 33% energy consumption compared to AMBs with constant stiffness. DSC for AMB systems offers benefits like lower risk of rotor-stator collisions, preventing coil burnouts, and improved energy efficiency.

The vortex dynamics characteristics in a pump-turbine: A rigid vorticity analysis while varying guide vane openings in turbine mode

In off-design conditions, pump-turbines generate vortex structures of varying scales and intensities, jeopardizing energy conversion due to unstable flow phenomena. While off-design pump-turbine internal flow dynamics have been analyzed, understanding the spatiotemporal evolution of complex vortex structures within runner blade passages, which are prone to inducing hydraulic instabilities, has to be still addressed properly. This paper applies the rigid vorticity theory, also known as Liutex, to explore vortex characteristics in the pump-turbine under different guide vane openings during turbine mode operation. The investigation focuses on three main aspects: i) spatial distribution characteristics, ii) temporal evolution characteristics, and iii) vortex morphological features along with deformation mechanisms. Results showed that the suction surface side of the blade's trailing edge commonly experiences significant shear effects, while vortices tend to emerge on both pressure and suction surface sides. Under small Guide Vane Opening (GVO) condition, vortices in blade passages show periodic evolution, and Enstrophy of the Rigid Vorticity Dilatation Term (ERDT) predominantly contributes to the helical deformation of these vortices. Conversely, under large GVO condition, vortices maintain high helicity and remain stable. This study provides insights to reduce hydraulic instability in pump-turbines and optimize energy conversion efficiency. The proposed Reynolds-averaged transport equation for enstrophy of the rigid vorticity and the relative streamline coordinate system provide advanced tools for analyzing unstable flow structures.

Effect of reinforcement ratio and textile pre-impregnation on the mechanical properties of flax textile reinforced sulfoaluminate matrix

This study evaluates the effect of reinforcement ratio and textile pre-impregnation on the tensile behavior of flax textile, embedded in an inorganic CSA matrix (sulfoaluminate cementitious matrix), known as Fabric Reinforced Cementitious Matrix (FRCM). Two reinforcement ratios of (3 and 6%) and two impregnation techniques (polymeric and mineral) are applied. Direct tensile tests are conducted on FRCM specimens as well as on bare flax textiles featuring three configurations: NP (non-impregnated), PP (polymeric-impregnated), and PM (mineral-impregnated), between 1L (one layer) and 2L (two layers) of flax textile. The results show a direct correlation between the reinforcement ratio and the enhancement of mechanical properties, with a notable 44% increase in mechanical strength observed for NP FRCM specimens between 1L and 2L of flax textile. Mineral pre-impregnation enhances yarn-cement matrix bonding inside FRCM, while FRCM specimens with polymeric-impregnated textiles have limited influence on the mechanical properties due to premature failure. Polymeric impregnation has a pronounced effect when applied to bare flax textiles, with PP flax textiles demonstrating exceptional mechanical strength and rigidity, reaching up to 480 MPa and 37 GPa, respectively. In contrast, this effect was mitigated when employing PP textiles in FRCM specimens, where the lowest fabric efficiency reached 12% for the 2L.PP configuration suggests significant chemical incompatibility between epoxy resin and CSA matrix. Mineral-impregnated specimens display consistent efficiency regardless of reinforcement ratio, suggesting a novel and homogeneous distribution of cement matrix particles within the yarns of textiles. Two distinct failure modes of FRCM are observed in this study, a delamination for PP configurations and a fiber pullout for NP and PM configurations. No effect of reinforcement ratio is remarked on the failure mode. The cracking mode in PM FRCM configurations showcased improved aesthetics, durability, and elongation after rupture (6.28%). As a result, 2L.PM FRCM is the best configuration in terms of mechanical strength, rigidity, ductility, and durability.

Potential Biodegradable Sticker Based on Carrageenaan and Chitosan with Addition of Lauric Acid: A Mini Review

Plastic pollution is a significant problem with detrimental effects on the environment and human health. Conventional plastic stickers, widely used in various sectors, contribute to plastic waste accumulation and slow degradation. To address this issue, review has focused on developing biodegradable stickers made from natural polymers such as carrageenan and chitosan. Carrageenan, derived from red seaweed, forms gels and has potential as a biodegradable film due to its stability and high fiber content. Chitosan, derived from crustacean waste, is non-toxic and can act as a stabilizer, thickener, and protective layer in food products. However, chitosan alone has limitations in terms of brittleness and rigidity. Lauric acid, a medium-chain fatty acid found in coconut oil, can be added as a film-forming material to improve the mechanical properties and reduce water vapor permeability. Biodegradable films thickness, tensile strength & Percent elongation, and surface morphology play important roles in their quality characteristics. Biodegradable stickers made from lauric acid-based biodegradable films offer ink resistance, biodegradability, water resistance, and water solubility as key characteristics.

Experimental and numerical investigation of bolted steel endplate with bonded sleeve end connections for pultruded GFRP circular tubular hollow beams

The paper presents an experimental and numerical investigation of bolted steel endplates with bonded sleeve connections developed for connecting pultruded glass fibre-reinforced polymer (GFRP) circular tubular beams. The moment-rotational responses were investigated in detail in terms of initial rotational stiffness, moment capacity, and rotation capacity for all the connections. The effect of endplate thickness and bonded sleeve length was also investigated. Predominant failure modes include bending and yielding of thinner endplates, while thicker endplates with low bonded sleeve lengths exhibit splitting failure in the bonded GFRP beam region. Available design codes for steel joints were used to classify the developed connections in terms of rigidity and strength. The failure modes from the finite element models were well matched by the experimental observations, which include the deformation of the endplate and the cohesive failure within the bonded sleeve region with the GFRP beam.

Effect of Bending Rigidity and Nonlinear Strains on Free Vibration of Hemi-Ellipsoidal Shells

Abstract This paper focuses on free vibration of hemi-ellipsoidal shells with the consideration of the bending rigidity and nonlinear terms in strain energy. The appropriate form of the energy functional is formulated based on the principle of virtual work and the fundamental form of surfaces. Natural frequencies and their corresponding mode shapes are determined using the modified direct iteration method. The obtained results, which show a close agreement with previous research, are compared with those obtained based on the membrane theory. The effect of the support condition, thickness, size ratio, and volume constraint condition on frequency parameters and mode shapes is demonstrated. With the bending rigidity, shell thickness has a significant impact on the frequency, especially in higher vibration modes and in shells with a considerable thickness but the frequency parameter converges to that determined by using the membrane theory while the reference radius-to-thickness ratio is increasing. In addition, accounting for the bending rigidity solves the issue of determining natural frequencies and mode shapes of the shells using the membrane theory without the volume constraint condition. The obtained results also indicate that the free vibration analysis with bending is essential for the hemi-ellipsoidal shell with a base radius-to-thickness ratio of less than 100, which gives over 2.84% difference compared with that of the shell derived by membrane theory, and this allows engineers to perform the analysis in more applications.

Utilization of Microencapsulated Thyme Essential Oil for Aroma Treatment of Wool Fabric

Background: With rising global trends and changing lifestyles in fashion, beauty as well as healthcare, the awareness of consumers has enforced the evolution of specialty value-added textiles. Essential oils and basic aromatherapy ingredients are microencapsulated and applied to the materials to provide a therapeutic effect and long-lasting aromas. The present study was carried out to prepare thyme essential oil microcapsules using a complex coacervation technique. The prepared microcapsules were applied on wool fabric using pad-dry-cure method by optimizing various variables of aroma treatment.
 Methods: Thyme essential oil was used based on its aromatic and therapeutic properties. A complex coacervation technique of microencapsulation was used to prepare thyme oil microcapsules. The padding bath components and treatment variables were optimized based on the presence of microcapsules on wool fabric as observed under a stereo zoom microscope, aroma durability to washing and improved properties of treated material regarding bending length, flexural rigidity and crease recovery angle. The aroma treatment was given on wool fabric using pad-dry-cure method.
 Results: Optimized variables for aroma treatment were 60 g/l microcapsule gel, two g/l softeners and ten g/l binder concentration, 1:20 material to liquor ratio, 35 ºC temperature, and 30 minutes treatment time as at these conditions more number of microcapsules, longer wash durability and better fabric properties in terms of bending length, flexural rigidity and crease recovery angle were observed. Aroma-treated wool fabric were dried at 70 ºC temperature for 4 minutes and cured at 100 ºC for 60 seconds.
 Conclusions: Thyme essential oil has many reported therapeutic properties therefore microencapsulated thyme basic oil-treated wool fabric can be used for apparel, home, and healthcare textiles. Higher concentrations of microcapsule gel and lower concentrations of softener and binder promoted the deposition of a maximum number of microcapsules on wool fabric. Complex coacervation techniques of microencapsulation for preparation of thyme essential oil microcapsules and pad-dry-cure method to impart durable aroma treatment on wool are needed to acquire long term sustained finish.

SpikeShip: A method for fast, unsupervised discovery of high-dimensional neural spiking patterns.

Neural coding and memory formation depend on temporal spiking sequences that span high-dimensional neural ensembles. The unsupervised discovery and characterization of these spiking sequences requires a suitable dissimilarity measure to spiking patterns, which can then be used for clustering and decoding. Here, we present a new dissimilarity measure based on optimal transport theory called SpikeShip, which compares multi-neuron spiking patterns based on all the relative spike-timing relationships among neurons. SpikeShip computes the optimal transport cost to make all the relative spike-timing relationships (across neurons) identical between two spiking patterns. We show that this transport cost can be decomposed into a temporal rigid translation term, which captures global latency shifts, and a vector of neuron-specific transport flows, which reflect inter-neuronal spike timing differences. SpikeShip can be effectively computed for high-dimensional neuronal ensembles, has a low (linear) computational cost that has the same order as the spike count, and is sensitive to higher-order correlations. Furthermore, SpikeShip is binless, can handle any form of spike time distributions, is not affected by firing rate fluctuations, can detect patterns with a low signal-to-noise ratio, and can be effectively combined with a sliding window approach. We compare the advantages and differences between SpikeShip and other measures like SPIKE and Victor-Purpura distance. We applied SpikeShip to large-scale Neuropixel recordings during spontaneous activity and visual encoding. We show that high-dimensional spiking sequences detected via SpikeShip reliably distinguish between different natural images and different behavioral states. These spiking sequences carried complementary information to conventional firing rate codes. SpikeShip opens new avenues for studying neural coding and memory consolidation by rapid and unsupervised detection of temporal spiking patterns in high-dimensional neural ensembles.

SPaM: soft patch matching for non-rigid pointcloud registration.

3d reconstruction of deformable objects in dynamic scenes forms the fundamental basis of many robotic applications. Existing mesh-based approaches compromise registration accuracy, and lose important details due to interpolation and smoothing. Additionally, existing non-rigid registration techniques struggle with unindexed points and disconnected manifolds. We propose a novel non-rigid registration framework for raw, unstructured, deformable point clouds purely based on geometric features. The global non-rigid deformation of an object is formulated as an aggregation of locally rigid transformations. The concept of locality is embodied in soft patches described by geometrical properties based on SHOT descriptor and its neighborhood. By considering the confidence score of pairwise association between soft patches of two scans (not necessarily consecutive), a computed similarity matrix serves as the seed to grow a correspondence graph which leverages rigidity terms defined in As-Rigid-As-Possible for pruning and optimization. Experiments on simulated and publicly available datasets demonstrate the capability of the proposed approach to cope with large deformations blended with numerous missing parts in the scan process.

Formulas for Calculating the Deflections of a Triangular Truss of Spatial Cover

Statement of the problem. The scheme of triangular in terms of dome type cover is proposed. The construction is statically determinate. The formulas for the dependence of the deflection on the number of panels and sizes are derived by generalizing a series of individual solutions by induction. Materials and methods. The forces in the coating rods are performed by cutting nodes in symbolic form using operators of the Maple symbolic mathematics system. The unknown systems of equilibrium equations in projections on the coordinate axis include the reactions of vertical supports located on the sides of the truss. One of the corners of the truss also has a spherical support, one is cylindrical. The Maxwell—Mohr formula is used to calculate the deflection of the vertex. The analysis of sequences of coefficients in solutions for individual trusses with different numbers of panels yields expressions for common terms included in the desired calculation formula. Results. Formulas for the dependence of the deflections of the truss on the number of panels for a vertical load evenly distributed over the nodes of the truss and a horizontal wind load applied to one of the sides of the structure are obtained. The solutions have a simple polynomial form. The curves of the dependence of the horizontal displacement of the dome top on the number of panels reveal a minimum. Asymptotics of the solutions is identified. Conclusions. A scheme of a statically determinate symmetric spatial dome is developed and its mathematical model is constructed, allowing analytical solutions with an arbitrary number of panels. The identified dependencies can be used both to evaluate the accuracy of numerical solutions and to find optimal combinations of structural dimensions in terms of rigidity.

Force dipole interactions in tubular fluid membranes

We construct viscous fluid flow sourced by a force dipole embedded in a cylindrical fluid membrane, coupled to external embedding fluids. We find analytic expressions for the flow in the limit of infinitely long and thin tubular membranes. We utilize this solution to formulate the in-plane dynamics of a pair of pusher-type dipoles along the cylinder surface. We find that a mutually perpendicular dipole pair generically moves together along helical geodesics. Since the cylindrical geometry breaks the in-plane rotational symmetry of the membrane, there is a difference in flows along the axial (ẑ) and transverse (θ̂) directions of the cylinder. This in turn leads to anisotropic hydrodynamic interaction between the dipoles and is remarkably different from flat and spherical fluid membranes. In particular, the flow along the compact θ̂ direction of the cylinder has a local rigid rotation term (independent of the angular coordinate but decays along the axis of the cylinder). Due to this feature of the flow, we observe that the interacting dipole pair initially situated along the axial direction ẑ exhibits an overall “drift” along the compact angular direction θ̂ of the tubular fluid membrane. We find that the drift for the dipole pair increases linearly with time. Our results are relevant for non-equilibrium dynamics of motor proteins in tubular membranes arising in nature, as well as in vitro experiments.

A Review Assessment of Fiber-Reinforced Polymers for Maritime Applications

Composite materials, comprised of fibre-reinforced polymers, offer a high strength-to-weight ratio, making them excellent for the building of complex, lightweight structures in several industries, including the marine industry. There is an improvement in fuel efficiency and cost-effectiveness in general marine component developments as a result of the lightweight and flexible design characteristics. Fibre-reinforced polymer (FRP) composites are often used to construct boats, ships, and other marine compounds, such as the hull, column beams, piling structures, and other internal ship components, since they meet the aforementioned characteristics. In terms of durability, rigidity, and corrosion resistance, these FRPs may readily replace their conventional metal counterparts. So, thisreview gives an overview of FRP composites' application in marine industries for various potential applications. Fibre-reinforced polymer composites offer a significant advantage in strength and weight when compared to conventional materials.

Sewing and adhesive bonding technologies for smart clothing production

PurposeThis paper aims to present investigations of the influence of sewing and adhesive bonding technology on the aesthetic, mechanical and conductive properties of the e-textile package. Commercially available conductive textiles are tested for the production of e-textile package by most common cut-and-sewn clothing production technologies.Design/methodology/approachSewing, adhesive bonding and seam sealing technologies used to obtain e-textile packages with woven and knitted conductive textiles. Produced e-textile packages described in terms of thickness, bending rigidity and general appearance. Exploitation properties of prepared samples tested by cycle tensile experiment and discussed on the basis of variation of linear electrical resistance property.FindingsResearch has shown that a reliable e-textile package can be obtained by applying cut-and-sew technology for conductive tracks of silver coated woven and knitted material. Seam sealing by thermoplastic polymer layer has an impact on the electrical and deformation properties of the samples. To create attractive smart clothing design, the appropriate joining method and its technological parameters must be chosen to ensure the durability and safety of e-textile packages.Originality/valueThe findings of the research are of substantial value for the production of e-textiles by cut-and-sewn technologies. The required shape of the conductive textile element for various applications can be cut and joined to the garment parts using traditional sewing or adhesive bonding techniques.

A comparative study of conventional FRET and light harvesting properties of Rh-110/Rh-6G and Rh-19/Rh-B organic dye pairs impregnated in sol-gel glasses

Two different pairs of laser dyes, Rhodamine-110 (Rh-110)/Rhodamine-6G (Rh-6G) and Rhodamine-19 (Rh-19)/Rhodamine-B (Rh-B) (the first dye in each pair as a donor and the second as an acceptor) were impregnated in silica samples prepared by the sol-gel method and spectroscopically studied using absorption and steady-state fluorescence techniques. The critical transfer distance (R0), actual distance (r) between the donor and acceptor, overlap integral [J()], FRET (fluorescence resonance energy transfer) efficiency (E), and antenna effect efficiency (AE) were investigated in detail based on the variation in acceptor concentration. The FRET efficiency, antenna effect efficiency, and actual donor-acceptor distance for Rh-110/Rh-6G and Rh-19/Rh-B dye pairs corresponding to acceptor concentration ranges (3.83 to 7.65) × 10−5 M l−1 and (3.71 to 8.34) × 10−5 M l−1, respectively, were found to be in the ranges of 57.38% to 74.89%, 36.97% to 24.13%, 5.44 nm to 4.77 nm, and 77.01%. Furthermore, maximum FRET efficiencies of 85.68% and 87.63% and antenna effect efficiencies of 36.97% and 40.95% for Rh-110/Rh-6G and Rh-19/Rh-B, respectively, were also reported. Our results demonstrate the superior FRET efficiency of Rh-19/Rh-B over Rh-110/Rh-6G dye pair in sol-gel glasses, while the antenna effect efficiency of Rh-110/Rh-6G is higher than that of Rh-19/Rh-B for the same donor to acceptor (D/A) ratio. Finally, Rh-110/Rh-6G is a better energy harvester than the Rh-19/Rh-B dye pair at the common D/A ratio. These results are explained in terms of molecular structure similarity, polarity, and rigidity of donor and acceptor.

Identifying Optimal Locations for Hardwood CLT Plants in Tennessee: Application of a Spatially Explicit Framework

Abstract The prospect of using mass timber products, such as cross-laminated timber (CLT), for building material has increased in recent years because of the advantage of these products over their substitutes in terms of structural rigidity, cost efficiency, and climate benefits. However, the American National Standard developed for CLT currently applies to softwood only. With the expected increase in the market for CLT, the supply chain needs to address the projected rise in demand for hardwood as well. Promoting the production of hardwood mass timber like CLT requires studying the feasibility of quality hardwood lumber supply and identifying the optimal locations for investing capital in CLT manufacturing plants. By presenting a case from Tennessee, this study provides a spatially explicit framework to use a variety of factors such as transportation networks, proximity to sawmills, sawmill capacity, and roundwood supply to identify optimal CLT plant locations. Specifically, fuzzy multicriteria analysis was used to identify potential locations, which provided inputs for a location-allocation model to identify optimal locations for CLT plants. Among the several potential locations, three optimal locations suitable for CLT plants were identified with 12,504 thousand cubic feet (MCF) annual production potential of CLT panels in Tennessee. Although increasing transportation distance for lumber procurement would increase CLT production capacity, it would also result in increased lumber supply costs. Potential investors and regional planners interested in using hardwood forest products can benefit from these findings to locate suitable sites for new investment.

V11-11 A 3-D PRINTED SYNTHETIC VAS DEFERENS FOR MICROSURGERY PRACTICE AND TRAINING

You have accessJournal of UrologyCME1 Apr 2023V11-11 A 3-D PRINTED SYNTHETIC VAS DEFERENS FOR MICROSURGERY PRACTICE AND TRAINING Parth Joshi, Brian Gillette, and Richard Schoor Parth JoshiParth Joshi More articles by this author , Brian GilletteBrian Gillette More articles by this author , and Richard SchoorRichard Schoor More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003337.11AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Microsurgery is difficult to perform and to teach. While other models for microsurgical practice exist, such as rubber tubing, dog neuter specimens, bull reproductive tracts, and human cadaver specimens, these are either not realistic enough to be useful as practice tools or are expensive or are not readily available. We believe that practicing microsurgery improves performance in real world conditions. As such, in order to become better microsurgeons ourselves and for our patients and to improve the quality of microsurgical training for our residents, we developed a synthetic vas deferens that has the physical characteristics of native human vas deferens. This video demonstrates the results of that endeavor. METHODS: We determined the physical characteristics of native human vas deferens in terms of inner lumen diameter, outer diameter, flexibility, axial rigidity, and tactile similarity using previously published anatomic studies, ultrastructural and imaging research and professional knowledge. We then used to a 3-D printer to create a cylindrical tube that had similar characteristics to native vas deferens and then tested it by performing anastomoses on the model using 7-0, 8-0, and 9-0 suture. After a process of trial and error, we eventually developed a working prototype that met our specifications. RESULTS: The synthetic 3-D printed vas deferens models had similar inner luminal diameter and outer diameter to native human vas deferens. The synthetic vas deferens had a similar tactile feel and physical characteristics as native vas. Surgical placement of 7-0, 8-0, and 9-0 nylon suture into the wall of the synthetic vas deferens and its lumen mimicked closely the experience of operating on native vas deferens. While tying good quality square knots was straightforward using 7-0 and 8-0 nylon suture, the synthetic vas deferens was too springy for the 9-0 suture and often resulted in either air-knots or suture breakage. However, by using excellent microsurgical techniques, it was possible to perform a quality modified one layer anastomosis using our 3-D printed synthetic vas deferens. The experience of practice with our model system simulated the experience of doing an actual anastomosis on a human. Aside for research and development costs, the cost for each synthetic vas specimen is less than $1.00 and the specimens have an unlimited shelf-life. CONCLUSIONS: The time to learn microsurgery or to practice it is not when the patient is on the operating table. We have developed a excellent, inexpensive, and readily available simulation vas deferens that is useful for both the experienced microsurgeon and the trainee or novice. Our research team is continually refining the synthetic vas deferens so that it becomes more lifelike and better accommodates 9-0 sutures and even everted 10-0 inner layer suture placement. Our goal is to share this technology with other training programs and standardize microsurgical education nationally and internationally. Source of Funding: Internal funding © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e1002 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Parth Joshi More articles by this author Brian Gillette More articles by this author Richard Schoor More articles by this author Expand All Advertisement PDF downloadLoading ...

Evolution of degradation mechanism and fixation strength of biodegradable Zn–Cu wire as sternum closure suture: An in vitro study

This work reports the first in vitro study on the in-situ biodegradation behaviour and the evolution of fixation strength of Zn–Cu alloy wires in a simulated sternum closure environment. Zn–Cu wires were used to reapproximate the partial bisected sternum models, and their fixation effect was compared with traditional surgical grade 316 L stainless steel (SS) wires in terms of fixation rigidity, critical load, first/ultimate failure characteristics. The metal sutures were then immersed in Hank's balanced salt solution for 12 weeks immersion period, and their corrosion behaviours assessed.Zn–Cu wires showed similar fixation rigidity at 70.89 ± 6.97 N/mm as SS, but the critical load, first failure and ultimate failure characteristics were inferior to SS. The key challenges that limited the fixation effect of the Zn–Cu wires were poor mechanical strength, short elastic region, and strain softening behaviours, which resulted in poor load-bearing capabilities and reduced the knot security of the sutures. The in-situ biodegradation of the Zn–Cu suture was accompanied by the early onset of localised corrosion within the twisted knot and the section located next to the incision line. Crevice corrosion and strain-induced corrosion were the dominant mechanisms in the observed localised corrosion. The localised corrosion on the Zn–Cu sutures did not lead to a significant shift in fixation rigidity, critical load and the first failure characteristics. The findings suggest that the Zn-based biodegradable metallic wires could be a promising sternum closure suture material once the limitations in mechanical characteristics are addressed.