Higher Tensile Load Research Articles

Discuss on Preparation Method of Composite Sports Equipment Based on Stretchable Nanofiber Fabric

Stretchable nanofiber fabrics refer to fabrics woven with elastic nanofibers, and nanofibers are defined as fibers with a diameter less than 100 nm. For example, nanofibers are implanted on the surface of the fabric to form a stable gas film. The biphobic interface can be used for the purification and filtration of sports equipment, chemical products, medical drugs and other products. The development of sports is increasingly dependent on science and technology, and stretchable nanofibers, as an emerging field of science and technology, are undoubtedly widely used in sports materials. This article first explains the role and background of stretchable nanofiber fabrics in sports equipment, and explains related methods, such as the slurry method for preparing rubber thermally conductive composites in sports equipment, and testing the thermal conductivity and thermal conductivity of composite materials. Diffusion coefficient, density and specific heat capacity; and then explain the polyrhodanine coating method, coating stretchable nano fabric, testing its mechanical properties and thermal conductivity, calculating the agglomeration phenomenon of particles in the rubber, you can get the wrapped PRh- The effect of BNNSs’ self-aggregation is suppressed; then the stress and strain of the nano-layer are tested using electrospinning technology, that is, the mechanical properties; finally, the tensile test of carbon fiber three-directional nano-fabric sports composite material is carried out, the tensile model is set, and the test is performed The strain and deformation in the stretching process at 0° and 90°, the load change and tensile elongation at break of the two are analyzed, the tensile attenuation rate in the 0° direction is lower than the attenuation rate in the 90° direction, 0° The tensile elongation at break in the direction of 90° is less than the tensile elongation at break in the direction of 90°, and one of the differences is judged that there is no carbon nanofiber on the parallel load in the 90° direction. The application of the above, taking bicycle tires and golf clubs as examples, combined with the average expected lift and 90° three-dimensional weaving method, the tensile strength direction can be obtained. This nanofiber three-dimensional weaving method has a higher tensile load than the composite material in the 90° direction. The average expected improvement of the ordinary weaving method is 36.1%, and the use of 90° three-dimensional nano fabric materials can improve the performance of sports equipment under this material by 16.9% to 51.8%.

Analysis and optimization of rivet load distribution in multi-rivet connections of thermoplastic composite rivets

GF/PP thermoplastic composite components predominantly employ metallic fasteners, leading to corrosion and weight issues. This study utilized an extrusion process to fabricate GF/PP thermoplastic composite rivets with properties akin to laminated panel materials. Through the controlled application of heat and pressure to the rivet ends, a novel connection structure was established. The article fabricated thermoplastic composite joints with varying end configurations and compared them with metallic rivet joints. Emphasizing the convex form, diverse multi-rivet links were crafted for single-lap tensile samples. Integrating tensile tests and strain gauge measurements, this research explored load distribution patterns across diverse rivet quantities and assessed the impact of size on distribution. Furthermore, finite element software was used to dissect the load distribution patterns and failure mechanisms in the multi-riveted connection structure. Drawing from experimental findings, convex GF/PP rivets exhibited an 18% higher tensile load than metallic ones, with a simultaneous 32% weight reduction. In multi-rivet connections, end rivets demonstrated higher load-bearing capacity. Enhanced spacing and plate width improved load distribution, elevating joint load capacity by 7% (spacing 25 mm to 55 mm) and 6% (width 30 mm to 55 mm). The simulation results indicate that increasing the spacing reduces the stress concentration at the first nail location.

Expanding the Scene of Tunnel Behaviour Through the DEM Model: a Case Study from ZaB-Zentrum Am Berg

The displacement of a tunnel plays a crucial role in conventional tunneling methods, serving as a key parameter for support requirement. Therefore, analyzing tunnel displacement is important for ensuring safety and optimizing costs by determining the appropriate level of tunnel support and installation time. Numerical analysis methods are commonly employed for assessing tunnel displacement, and two widely recognized approaches used worldwide are the continuum and discontinuum methods. While previous studies have highlighted differences in the analysis results obtained from these two methods, the magnitude of such disparities has not been extensively explored. Hence, the objective of this study is to quantify the extent of variation between the two methods through various scenarios, encompassing unsupported and supported excavated ground. Specifically, the focus is on tunnel displacement and the tensile force generated on axial tunnel supports, such as rock bolts. To facilitate this investigation, three tunnel sections from the Zentrum am Berg, tunnel research centre located in Austria, are utilized. The results show that discontinuum models exhibit higher displacements and higher tensile loads on axial support than continuum numerical models of the same tunnel geometry and equivalent rock masses. We show that discontinuum models can also capture asymmetric behaviour, and thus should be preferentially used in fractured rock masses where displacement of rock blocks dominate the rock mass behaviour.

A novel composite connecting rod: study on mechanical and dynamic behaviour through experimental and finite element approach

The increase in strength and stiffness of a metal matrix composite connecting (MMC) rod when compared to conventional rods have motivated researchers in this area. This opens a new window for the present research, here Al7075 alloy and Al7075-based composite connecting rods were fabricated by machining composite blocks using computer numerical control machining centre. Al7075-based composite connecting rods comprises of 91 % Al7075, 3 % hexagonal boron nitride (h-BN) and 6 % of zirconium dioxide (ZrO2). Modal characteristics and mechanical performance of the prepared components were analysed. An experimental modal analysis was conducted on the connecting rod under fixed-free condition to identify the natural frequency and its mode shapes, further the outcomes were compared with the numerical values. The ANSYS workbench is used to estimate the component's failure load based on finite element (FE) approach. The results obtained from modal analysis revealed that the composite connecting rod is more dynamically stable than its unreinforced counterpart. Composite connecting rods also showed better load-bearing capacity as compared to Al7075 in terms of tensile and compressive loading. Failure load analysis results indicate that under compressive load the component bends along the shank (I-beam), while under tensile load, cracks originate at the section connecting the piston pin end and the I-beam. The composite connecting rod sustained 13.5 % higher compressive load and16.5 % higher tensile load than the Al7075 connecting rod, making it a suitable alternative material. The failure mechanisms have been investigated by extensive scanning electron micrography of fabricated connecting rods.

Effect of long‐term stress aging on aluminum‐BFRP hybrid adhesive joint's mechanical performance: Static and dynamic loading scenarios

AbstractComposite‐aluminum hybrid adhesive joints represent an ideal solution for designing lightweight structures for the marine industry. However, seawater aging is a serious concern, limiting the safe service life of the joint. Notably, efforts to understand the impact of aging have largely focused on the short‐term periods without considering actual operating conditions. Here, we report the mechanical performance of hybrid joints subjected to the long‐term stress aging. Besides, we modified the epoxy adhesive with halloysite nanotubes (HNTs) to limit the aging driven adhesive degradation and improve the adhesive's rigidity. We evaluated mechanical performances of hybrid joints by performing tensile, flexural, and drop‐weight impact tests. While we increased the load‐carrying capacity by over 25% with the HNTs modification before the stress aging process, modified adhesive withstood almost 55% higher tensile load than the neat epoxy adhesive after six‐month stress aging. The modified adhesive also absorbed 41% less impact energy, indicating the efficiency of HNTs on limiting the degradation due to the stress aging. Furthermore, the damage mode transformed from adhesion to cohesion, thanks to the improved adhesive‐composite interface performance. We envisage that these exciting results will pave the way for designing robust hybrid joints for the marine industry.

An investigation of mechanical and electrical properties of friction stir welded Al and Cu busbar for battery pack applications

The aluminum and copper (Al–Cu) busbar is widely used as a core component in Lithium-Ion (Li-ion) batteries. The Al–Cu busbar is challenging to fabricate with the traditional welding processes because of its high thermal conductivity. The Al–Cu busbar is fabricated using the friction stir welding method in the present study. The effect of temperature and vibration generated during the welding process on intermetallic compounds (IMCs) is studied using the effective formation model and found that Al2Cu is the first to form at the interface. The IMC formation at the joint interface had detrimental (Al-rich IMC) and beneficial (Cu-rich IMC) effects. The presence of detrimental IMCs affects the joint strength of about 36% as compared to the sample with the highest tensile load. The surface electrical conductivity is measured by using a Gaussian profile method and found in the range of 0.94–5.37 μ Ω·mm. The welded samples with the presence of Al2Cu3 and Al4Cu9 IMC at the interface are found to have higher electrical conductivity. Interestingly, the sample with a higher tensile load had observed higher electrical conductivity due to the formation of Cu-rich IMC, i.e., Al4Cu9.

More Powerful Twistron Carbon Nanotube Yarn Mechanical Energy Harvesters.

Stretching a coiled carbon nanotube (CNT) yarn can provide large, reversible electrochemical capacitance changes, which convert mechanical energy to electricity. Here, it is shown that the performance of these "twistron" harvesters can be increased by optimizing the alignment of precursor CNT forests, plastically stretching the precursor twisted yarn, applying much higher tensile loads during precoiling twist than for coiling, using electrothermal pulse annealing under tension, and incorporating reduced graphene oxide nanoplates. The peak output power for a 1 and a 30Hz sinusoidal deformation are 0.73 and 3.19kWkg-1 , respectively, which are 24- and 13-fold that of previous twistron harvesters at these respective frequencies. This performance at 30Hz is over 12-fold that of other prior-art mechanical energy harvesters for frequencies between 0.1 and 600Hz. The maximum energy conversion efficiency is 7.2-fold that for previous twistrons. Twistron anode and cathode yarn arrays are stretched 180° out-of-phase by locating them in the negative and positive compressibility directions of hinged wine-rack frames, thereby doubling the output voltage and reducing the input mechanical energy.

A biomechanical analysis of flowable injectable calcium bone void filler on acromial tensile stresses: a method to reduce acromial stress fractures

IntroductionAcromial fracture after reverse shoulder arthroplasty (RSA) is a known complication. These fractures are difficult to treat and negatively impact outcomes in patients who experience them. As the rate of RSA increases worldwide, it will be valuable to identify ways to decrease the risk of postoperative acromion fractures. The goal of this study was to evaluate if injecting an acromion with a synthetic bone graft substitute can strengthen the acromion and theoretically provide a means to reduce the incidence of acromial fractures after reverse shoulder arthroplasty. MethodsEight cadaveric scapulae matched pairs (n = 16) were randomly allocated to two groups with the contralateral side in the different group. The experimental group (n = 8) had synthetic bone graft filler (CERAMENT) injected while the control group (n = 8) did not. The experimental group had the injection both through an anterolateral and posterolateral corners of the acromion for filling of the acromion. Each scapulae was fixed to the base of a MTS Bionix test frame. Cantilever bending testing to failure was performed on each scapulae with a loading rate of 0.1 mm/s. Failure load (N), force (N/mm), and displacement (mm) were recorded and compared for each specimen. CT scans and fluoroscopy imaging was performed for each specimen before and after testing. ResultsAll 16 specimens were available for analysis. The experimental group was injected with 4 cc +/- 0.5 showed material-to-area ratio fill of 39% mid-acromial area and 38% of the acromial area at the Levy I-II junction. The load to failure was 396 N +/- 89 in the control group and 521 N +/-147 in the experimental group (P = .017). Displacement at failure was less for the control group at 8 mm +/- 2 mm compared to the experimental group at 12 mm +/- 4 mm (P = .051). All samples failed with Levy Type II acromion fractures. ConclusionThis biomechanical study showed that injection of 4 cc of flowable synthetic bone graft filler into the acromion increased load to failure 32% compared to control scapulae. The stiffness was greater and the displacement before failure was greater in the control group compared to the experimental group, although not statistically significant. The ability for the acromion to plastically deform a greater distance prior to failure allow for greater resistance to fracture under higher tensile loads when flowable bone graft filler is injected. Level of evidenceBasic Science Study.

Comparison of the mechanical properties of biodegradable and titanium osteosynthesis systems used in oral and maxillofacial surgery

To guide the selection of osteosynthesis systems, this study compared the mechanical properties of biodegradable and titanium osteosynthesis systems. SonicPins Rx and xG were subjected to pull-out tests. Additionally, 15 biodegradable (Inion CPS 2.0 and 2.5 mm; LactoSorb 2.0 mm; Macropore 2.0 mm; Polymax 2.0 mm; BioSorb FX 2.0 mm; ResorbX 2.1 mm; Osteotrans-MX 2.0 mm with plate thicknesses 1.0 and 1.4 mm; SonicWeld Rxplate/Rxpins, xGplate/Rxpins and xGplate/xGpins 2.1 mm without and with tapping the burr hole) and six titanium (CrossDrive (2006), CrossDrive (2018), MaxDrive; all 1.5 and 2.0 mm) straight, four-hole osteosynthesis systems were evaluated. All systems were subjected to tensile, bending and torsion tests. Pull-out loads of the SonicPins were comparable (P = 0.423). Titanium systems’ tensile loads were higher than biodegradable systems (P < 0.001). CrossDrive (2018) and MaxDrive systems’ tensile and torsional stiffness were lower, accompanied with higher ductility, than corresponding CrossDrive (2006) systems (P < 0.001). Bending stiffness of 1.5 mm titanium systems was comparable to, and of the 2.0 mm systems higher than, all biodegradable systems (P < 0.001). Regarding biodegradable systems, Inion CPS 2.5 mm had highest tensile load and torsional stiffness, SonicWeld 2.1 mm highest tensile stiffness, and BioSorbFX 2.0 mm highest bending stiffness (P < 0.001). On the basis of the results of this study, the CrossDrive (2018) and MaxDrive 1.5 mm titanium systems are recommended for midface fractures (e.g., zygomatic or maxillary fractures) and osteotomies (e.g., Le Fort I osteotomy), and the CrossDrive (2018) and MaxDrive 2.0 mm titanium systems for mandibular fractures and osteotomies when a titanium osteosynthesis system is used. When there is an indication for a biodegradable osteosynthesis system, the SonicWeld 2.1 mm or BioSorbFX 2.0 mm are recommended for midface fractures and osteotomies, and the Inion CPS 2.5 mm biodegradable system for mandibular osteotomies and non-load bearing mandibular fractures, especially when high torsional forces are expected (e.g., mandibular symphysis fractures).

Corrosion of Ni-Ti Rotary Instruments: A Review

The nickel-titanium (Ni-Ti) alloys used in endodontics contain 56% Ni and 44% Ti. The 2 unique features related to clinical dentistry (i.e., shape memory effect and superelasticity) are due to the transition from austenite to martensite in Ni-Ti alloy. When a superelastic Ni-Ti alloy undergoes a low tensile loading, normal elastic behavior occurs. In fact, at higher tensile loads, the elastic stress may reach a level at which there is extended horizontal region of elastic strain. The shape-memory property of Ni-Ti is derived from an atomic arrangement different from that of alloys like stainless steel. The purpose of this paper was to review the unique features of this alloy and mechanism of corrosion.

Technology Focus: Coiled Tubing (June 2019)

Technology Focus During the past several years, lean philosophies, methods, and techniques have been applied steadily and increasingly within the upstream segment of the oil and gas industry. Perhaps one of the more notable areas for this growth has been in unconventional well completions and field development with references to such endeavors as the “well factory.” In part, this has been focused on optimizing well and pad construction to establish a uniformity of processes and equipment. This allows a greater focus on elimination of the various forms of waste, as defined in lean concepts, to drive various efficiency gains. However, applying these concepts to well interventions proves challenging. The coiled-tubing (CT) industry, like other well-intervention segments, has applied lean philosophies to some aspects of its management, operations, processes, and equipment. When it comes to CT application to specific in-well operations, no two wells are the same. Even though the operations may be nominally similar, well variables such as temperature, pressure, depth, and fluids can make it difficult to understand the cause and effect. The continued high activity level in the unconventional and shale well segments in the US has provided a unique opportunity to apply the scientific method to CT interventions because of a reduced number of variables and the fact that the plan/do/check/adjust cycle can be applied. Paper SPE 191689 exemplifies the use of the scientific method for in-well CT operations. Another way to bring efficiency to operations is through the sharing or compounding of data to increase the sample group. Conflicts of interest or fair-competition concerns can make this approach difficult. One paper in the recommended additional reading list, SPE 194277, may offer a practical solution. Part of the operational challenges for CT in unconventional wells is the lateral length that must be accessed. Paper SPE 194300 also shows that these challenges are being encountered similarly offshore and how they are being addressed. Additionally, the continued development of high-performance CT steels and workstring designs (paper SPE 194255) drives these significant enabling technologies in meeting the challenges. The continuing general trend to operate with larger-diameter CT at higher tensile loads brings other operational issues, such as avoiding imparting mechanical damage to the CT’s surface by handling the equipment. Examining how the CT injector might be optimized by design, or by usage, from a finite-element-analysis and a mathematical perspective is discussed in paper SPE 194254 and introduces an interesting factor to the discussion. I am sure that there will be diverse opinions on this work. SPE 194300 Highly Engineered 2.375-in. Coiled Tubing Provides Effective and Reliable Interventions on 30,000-ft Megareach Wells Offshore Abu Dhabi by Irma Galvan, Global Tubing, et al. SPE 194277 Remote Monitoring and Modeling of Coiled-Tubing Operations in Real Time by Paul Brown, CoilData, et al. SPE 192000 Rigless Intervention To Secure Internal Blowout Monitoring Gas Wells Offshore Brunei by Axemi Leong, Halliburton, et al.

The lasso-loop, lasso-mattress and simple-cinch stitch for arthroscopic rotator cuff repair: are there biomechanical differences?

Various stitching techniques have been described to facilitate arthroscopic repair of rotator cuff tears. The aim of the present study was to compare the biomechanical properties of the lasso-loop, lasso-mattress and simple-cinch stitch for rotator cuff repair. Twelve infraspinatus tendons were harvested from sheep and split in half. The tendons were randomized into three different stitch configuration groups for biomechanical testing: lasso-loop, lasso-mattress and simple-cinch stitch. Each specimen was first cyclically loaded on a universal materials testing machine under force control from 5 to 30N at 0.25Hz for twenty cycles. Then, each specimen was loaded to failure under displacement control at a rate of 1mm/s. Cyclic elongation, peak-to-peak displacement and ultimate tensile load were reported as mean±standard error and compared using one way analysis of variance. The type of failure was recorded. No differences in cyclic elongation (1.31±0.09mm for the simple-cinch vs. 1.49±0.07mm for the lasso-mattress vs. 1.61±0.09mm for the lasso-loop stitch, p=0.063) or peak-to-peak displacement (0.58±0.04mm for the simple-cinch, 0.50±0.03mm for the lasso-mattress and 0.62±0.06mm for the lasso-loop stitch, p=0.141) were seen between all tested stitch configurations. In the load-to-failure test, the simple cinch stitch (149.38±11.89N) and the lasso-mattress (149.38±10.33N) stitch demonstrated significantly higher ultimate load than the lasso-loop stitch (65.88±4.75N, p<0.001). All stitch configurations failed with suture pull out. The lasso-mattress and the simple-cinch stitch showed similar biomechanical properties with significant higher tensile loads needed for failure than the lasso-loop stitch.

An anatomical study of the pathophysiology of carotid cavernous sinus fistula associated with Le Fort III osteotomy.

Carotid-cavernous sinus fistula (CCF) is a rare complication occurring after the Le Fort osteotomy. We aimed to elucidate the cause of CCF in the Le Fort osteotomy. Eleven fresh cadavers were used. After craniotomy, a Le Fort III bipartition osteotomy was then performed. On the left side, both the lateral wall of the maxilla and the pterygomaxillary junction (PMJ) were divided, in addition to the conventional osteotomy line. On the right side, those parts were kept intact. After the osteotomy, a tensiometer was fixed to the skull base. The sensor was linked with the wall of the carotid artery in the cavernous portion. A down-fracture was then performed initially from the left, followed by the right. Tensile force data of both sides were recorded. In all cases, a higher tensile load was observed on the right side compared to the left side. In right side, two skull base fractures complexed with high pterygoid process fractures, and nine pure high fractures of the pterygoid process were identified. During down-fracture, the wall of the carotid artery experiences significant tensile load. The tensile load on the arterial wall may collapse the fine branches of the carotid artery in the cavernous portion.

Vibration analysis of a carbyne-based resonator in nano-mechanical mass sensors

Carbyne is a chain of C atoms held together by double or alternating single and triple chemical bonds, and has twice the tensile stiffness of carbon nanotubes (CNTs) and graphene sheets (GSs). In this study, we propose a nano-mechanical mass sensor using a tensioned carbyne resonator. The carbyne resonator is modeled as an equivalent continuum circular cross section beam with diameter 0.772 Å, Young’s modulus 32.71 TPa, shear modulus 11.8 TPa, Poisson’s ratio 0.386 and density 32.21 g cm−3. We analyze the resonant frequency of the proposed sensor carrying with a concentrated mass based on the Timoshenko beam theory and verify the theoretical approach using Rayleigh’s energy method and molecular dynamics simulation. The results show that the proposed mass sensor can measure a tiny mass with weight below 10−5 zg, and provide much higher sensitivity than CNTs- and GSs- based nano-mechanical mass sensors. In addition, the effects of carbyne length, mass position and tensile load on the frequency shift are also analyzed in detail, and it is preferred to use shorter carbyne and higher tensile load in the proposed mass sensor.

Comparison of sodium naphthenate and air-ionization corona discharge as surface treatments for the ethylene-tetrafluoroethylene polymer (ETFE) to improve adhesion between ETFE and acrylonitrile-butadiene-styrene polymer (ABS) in the presence of a cyanoacrylate adhesive (CAA)

This study compares two ethylene-tetrafluoroethylene (ETFE) surface activation treatments, namely chemical attack with a solution of sodium naphthenate and plasma erosion via air-ionization corona discharge in order to improve the adhesive properties of the ETFE. An experimental design was prepared for both treatments in order to assess the effect of the treatment characteristics on the tensile load needed to break the bond between the ETFE and the acrylonitrile-butadiene-styrene polymer (ABS) formed with a cyanoacrylate adhesive (CAA) applied between them. The reason for the selection of this problem is that both polymers are frequently used in the biomedical industry for their properties, and they need to be joined firmly in biomedical devices, and the cyanoacrylate adhesive is the adhesive traditionally used for fluoropolymers, in this case the ETFE, and the same CAA has also shown good adhesion with ABS. However, the strength of the bond for the triplet ETFE-CAA-ABS has not been reported and the improvement of the strength of the bond with surface treatments is not found in scholarly journals for modern medical devices such as stents and snares. Both treatments were compared based on the aforementioned design of experiments. The case where ETFE receives no surface treatment serves as the reference. The results indicated that the three factors evaluated (initial drying of the material, temperature of the chemical bath, and immersion time), and their interactions have no significant effect over the tensile load at failure (tensile strength) of the adhesive bond being evaluated. For the air-ionization corona discharge treatment, two factors were evaluated: discharge exposition time and air pressure. The results obtained from this experimental design indicate that there is no significant difference between the levels of the factors evaluated. These results were unexpected as the ranges used were representative of the maximum ranges permissible in manufacturing operations. As for the comparison of the treatments, it was determined that the treatments have statistically significant differences. It was also determined that there is a significant statistical difference between the processes where a surface treatment is performed and the process where no surface treatment is applied to the ETFE. The chemical treatment results in a higher tensile load at failure (tensile strength) of 276.6 N on average, the air ionization treatment has an average of 248.4 N, and the process with no treatment has the lower ultimate tensile strength average of 53 N. This comparison has demonstrated that the best treatment is the chemical treatment with sodium naphthenate under the conditions tested.

Study on cold metal transfer welding–brazing of titanium to copper

3mm Pure titanium TA2 was joined to 3mm pure copper T2 by Cold Metal Transfer (CMT) welding–brazing process in the form of butt joint with a 1.2mm diameter ERCuNiAl copper wire. The welding–brazing joint between Ti and Cu base metals is composed of Cu–Cu welding joint and Cu–Ti brazing joint. Cu–Cu welding joint can be formed between the Cu weld metal and the Cu groove surface, and the Cu–Ti brazing interface can be formed between Cu weld metal and Ti groove surface. The microstructure and the intermetallic compounds distribution were observed and analyzed in details. Interfacial reaction layers of brazing joint were composed of Ti2Cu, TiCu and AlCu2Ti. Furthermore, crystallization behavior of welding joint and bonding mechanism of brazing interfacial reaction were also discussed. The effects of wire feed speed and groove angle on the joint features and mechanical properties of the joints were investigated. Three different fracture modes were observed: at the Cu interface, the Ti interface, and the Cu heat affected zone (HAZ). The joints fractured at the Cu HAZ had higher tensile load than the others. The lower tensile load fractured at the Cu interface or Ti interface was attributed to the weaker bonding degree at the Cu interface or Ti interface.

Extracorporeal Shock Wave Therapy in Treatment of Delayed Bone-Tendon Healing

Background Extracorporeal shock wave therapy is indicated for treatment of chronic injuries of soft tissues and delayed fracture healing and nonunion. No investigation has been conducted to study the effect of shock wave on delayed healing at the bone-tendon junction. Hypothesis Shock wave promotes osteogenesis, regeneration of fibrocartilage zone, and remodeling of healing tissue in delayed healing of bone-tendon junction surgical repair. Study Design Controlled laboratory study. Methods Twenty-eight mature rabbits were used for establishing a delayed healing model at the patella–patellar tendon complex after partial patellectomy and then divided into control and shock wave groups. In the shock wave group, a single shock wave treatment was given at week 6 postoperatively to the patella–patellar tendon healing complex. Seven samples were harvested at week 8 and 7 samples at week 12 for radiologic, densitometric, histologic, and mechanical evaluations. Results Radiographic measurements showed 293.4% and 185.8% more new bone formation at the patella–patellar tendon healing junction in the shock wave group at weeks 8 and 12, respectively. Significantly better bone mineral status was found in the week 12 shock wave group. Histologically, the shock wave group showed more advanced remodeling in terms of better alignment of collagen fibers and thicker and more mature regenerated fibrocartilage zone at both weeks 8 and 12. Mechanical testing showed 167.7% and 145.1% higher tensile load and strength in the shock wave group at week 8 and week 12, respectively, compared with controls. Conclusion Extracorporeal shock wave promotes osteogenesis, regeneration of fibrocartilage zone, and remodeling in the delayed bone-to-tendon healing junction in rabbits. Clinical Relevance These results provide a foundation for future clinical studies toward establishment of clinical indication for treatment of delayed bone-to-tendon junction healing.

Effect of Disinfecting Solutions on the Mechanical Properties of Orthodontic Elastomeric Ligatures

To assess the effect extended exposure to disinfectant solutions has on the tensile load at failure and glass transition temperature (T(g)) of orthodontic elastomeric ligatures. Elastomeric ligatures from three manufacturers: Rocky Mountain Orthodontics (RMO, Denver, Colo), American Orthodontics (AO, Sheboygan, Wis), and 3M Unitek (3M, Monrovia, Calif) were exposed to two disinfectant solutions, Vital Defense-D and Cidexplus, for up to 28 days. Unexposed ligatures were also tested. Tensile load at failure was determined by stretching the ligatures using a universal testing machine until they fractured. Glass transition temperature was determined using differential scanning calorimetry (DSC). For tensile load at failure and glass transition temperature of the ligatures, significant differences were observed among the different manufacturers and exposure times. Type of disinfectant solution was a significant factor with T(g), but not with failure load. The 3M ligatures had the highest tensile load at failure and most positive T(g) followed by AO and RMO, respectively. Compared to unexposed ligatures, strength significantly decreased after one hour of disinfectant exposure. Glass transition temperature was also significantly affected with extended disinfectant exposure, but the different disinfectants changed T(g) in opposite directions. Exposure of elastomeric ligatures to disinfectant solution for one hour or more decreases their strength.

Tensile deformation behavior of plasma-sprayed Ni–45Cr coatings

Deformation behavior of plasma-sprayed Ni–45Cr coatings was studied in terms of stress–strain relation and modulus changes under tensile loading. The tensile loading was applied in both directions parallel and perpendicular to the lamellar plane of the coatings. The influences of spray distance on Young's modulus and Poisson's ratio of the coatings were investigated. The Young's modulus was measured from both directions parallel and perpendicular to the lamellar plane. Results showed a linear relation between the stress and strain in the direction parallel to the lamellar plane. The similar linear stress–strain relation in the direction perpendicular to the lamellar plane was revealed only when the tensile loading with up to a certain value was applied, while a nonlinear stress–strain relation prevailed under a higher tensile load. The increase of the proportional limit of the coating was observed under repetitive tensile loading perpendicular to the lamellar plane. The modulus measured from the direction parallel to the lamellar plane changed from 78 GPa to 92 GPa. Spray distance showed minor effect on the Young's modulus. Moreover, the modulus measured from the direction perpendicular to the lamellar plane, changing from 48 GPa to 64 GPa, was lower than that obtained from the direction parallel to the lamellar plane. It is clear that plasma-sprayed metallic coating presented an anisotropic elastic behavior. In addition, it was found that the coatings yielded a Poisson's ratio of 0.13–0.15 which is lower than that of bulk materials. Spray distance also has no significant influence on the Poisson's ratio of coatings.

Rotator Cuff Repair: An Ex Vivo Analysis of Suture Anchor Repair Techniques on Initial Load to Failure

To determine the best combination of anchors and suture techniques for repairing torn rotator cuff tendons. Ex vivo biomechanical investigation. Sixty fresh-frozen sheep infraspinatus tendons were repaired using 6 different repair techniques: transosseous sutures with 2 sutures and mattress stitches; 2 suture anchors with 1 suture per anchor using either simple stitches, mattress stitches, or modified Kessler stitches; 2 suture anchors with 2 sutures per anchor using simple stitches; or 5 suture anchors with 1 suture per anchor and a mattress stitch pattern. No difference was identified between transosseous sutures (mean +/- SD, 147 +/- 68 N) and suture anchors (140 +/- 36 N) when 2 mattress stitches were used. The weakest construct with suture anchors was when the tendon was grasped with 2 suture anchors with 1 suture per anchor and a simple stitch pattern (72 +/- 25 N). Repair strength increased 2-fold with 2 suture anchors single loaded and a mattress stitch configuration (140 +/- 36 N; P = .026), 3-fold with 2 suture anchors single loaded and a modified Kessler stitch pattern (204 +/- 32 N; P < .001), and 3-fold with 2 suture anchors double loaded and a simple stitch suture pattern (212 +/- 39 N; P < .001). The highest tensile load was observed with 5 suture anchors in a double-row configuration, single loaded, that grasped the tendon with mattress stitches (336 +/- 59 N; P < .001). This study shows that in an ovine model, initial rotator cuff repair strength can be enhanced by increasing the number of suture anchors used in the repair and by using anchors that are double loaded with suture and suture configurations that pass more frequently through the tendon. The clinical relevance of this ex vivo investigation is that the initial load to failure of a rotator cuff repair may be increased by increasing the number of suture anchors, the number of sutures per anchor, or using suture patterns that grab more adjacent tendon fibers.