Maximum Load Force Research Articles

PHYSICAL CHARACTERIZATION AND MASS MODELING BY GEOMETRICAL ATTRIBUTES OF BLACK SAPOTE (Diospyros nigra (J.F.Gmel.) Perr.)

The fruit of black sapote (Diospyros nigra (J.F.Gmel.) Perr.) has been consumed in Mexico and Central America since pre-Hispanic times. They contain antioxidant compounds, minerals, and vitamins, making them valuable for nutraceutical and agro-industrial applications. Despite this, there is no scientific information on the physical and mechanical characterization of the fruit that helps in the design and development of protocols and equipment for storage, handling, processing, and added value for a better use of the fruit. In the present work, the physical and mechanical qualities of physiologically ripe black sapote fruit from the State of Hidalgo, Mexico, were characterized after one day of storage after harvest under environmental storage conditions. Models were also determined for the prediction of the mass of the fruit using their dimensional characteristics, finding that the quadratic models based on the volume of the ellipsoid (R2 = 0.8919) and width of the fruit (R2 = 0.8252) were the most appropriate to predict their mass. Likewise, a maximum compressive load force of 869.99 N and an apparent modulus of elasticity of 0.0.088 MPa were determined.

Development of a compact impact two-degree-of-freedom linear-rotary piezoelectric motor using one piezoelectric actuator.

A compact impact two-degree-of-freedom linear-rotary piezoelectric motor is proposed using a single actuator. The proposed piezoelectric actuator has a pair of deformation counteracting helical interdigitated electrodes on its outside surface, which can be divided into two parts. When the two parts of the piezoelectric actuator are driving under the same driving voltage signals, the motor can realize independent linear motion. When the two parts of the piezoelectric actuator are driving under the driving voltage signals with opposite duty cycles, the motor can realize independent rotary motion. The fabricated piezoelectric motor can produce a maximum average linear velocity of 1.9 and -2.3 mm/s with a saw-shaped driving signal of 400Vp-p (peak-to-peak driving voltage) at 9kHz. Experiments also show that the fabricated piezoelectric motor can realize a maximum average rotary velocity of 2440 and -2235 mrad/s with a driving signal of 400Vp-p at 9kHz. The maximum load force and torque of the prototype are about 0.4 N and 1.5mNm, respectively. The proposed motor provides a wide driving frequency and realizes high velocity in both linear and rotary motions.

NAMPT-Improved Mitochondrial Function Alleviates Degenerative Rotator Cuff Tendinopathy in Aged Mice.

Age-related rotator cuff tendinopathy (RCT) is associated with increased rotator cuff tear and postoperative retear rates. This study aimed to determine whether nicotinamide phosphoribosyltransferase (NAMPT) can alleviate degenerative RCT and prevent postoperative retears by reversing mitochondrial dysfunction in aged mice. We assigned 32 young (4 months) and 64 aged (19 to 20 months) male wild-type C57BL/6 mice to young, aged, and aged NAMPT-treated (ANAMPT) groups (n = 32 each). Mice in the ANAMPT group underwent subacromial injection with NAMPT-loaded fibrin gel, whereas the other 2 groups were injected with fibrin gel alone. Histological staining and each of the biomechanical and mitochondrial function tests were performed using 8 samples each. Histological staining in the aged group revealed decreased cellularity, disrupted fiber architecture, and reduced type-I collagen content inside tendon tissues proximal to the enthesis, demonstrating the spontaneous development of age-related degenerative RCT. Compared with the young group, the maximum tendon-to-bone failure load (4.22 ± 0.81 versus 5.52 ± 0.81 N, p = 0.0106) and maximum suture cut-through force (0.83 ± 0.08 versus 1.07 ± 0.10 N, p = 0.0006) of degenerated tendon tissues in the aged group were significantly lower. Significantly reduced nicotinamide adenine dinucleotide (NAD + ) levels, adenosine triphosphate (ATP) production, and citrate synthase activity indicated that mitochondrial dysfunction was closely related to the development of the degenerative RCT. Furthermore, NAMPT-improved mitochondrial function alleviated age-induced degenerative histological changes and increased the maximum failure load (5.32 ± 0.68 N, p = 0.0375) and maximum suture cut-through force (0.99 ± 0.13 N, p = 0.0285). Spontaneously developed degenerative RCT in aged mice mimicked the clinical situation in elderly patients. NAMPT-improved mitochondrial function could alleviate age-induced degenerative RCT and prevent postoperative suture cut-through of tendons with degenerative RCT. This study confirmed the spontaneous development of degenerative RCT in aged mice, which will facilitate future studies of this condition. The results also suggest that NAMPT offers a novel therapeutic approach for treating age-related degenerative RCT.

A study of a slim compact piezo inertia actuator

Most previously reported inertia actuators suffer from the problems of low speed and large size. To overcome these shortcomings, this study proposes a slim compact piezo inertia actuator based on the principle of stick–slip drive. Actuated by the transverse motion of a cantilever beam forming part of a monolithic elastomer, this actuator achieves a high velocity. The construction and basic operating principle of the actuator are discussed in detail. Commercial finite element analysis software is employed to determine the appropriate geometry for the monolithic elastomer. To study the actuator’s mechanical characteristics, a prototype is fabricated and a series of experimental tests are performed. According to the results of these tests, the maximum velocity and maximum load force are about 24.03 mm/s and 1.96 N, respectively, and the minimum step size is about 0.47 μm. It is shown that the inertia actuator based on a monolithic elastomer with a cantilever beam not only has a slim compact structure, but also exhibits good output characteristics.

A parasitic-inertia piezoelectric actuator with isosceles trapezoidal flexible mechanism base on parasitic motion exploration and asymmetrical installation

Parasitic-inertia piezoelectric actuators have been widely studied for their ability to achieve both high positioning accuracy and large working strokes. However, backward motion results in parasitic-inertia piezoelectric actuators with the disadvantages of low efficiency and abrasion of driving foot. In this study, a parasitic-inertia piezoelectric actuator with an isosceles trapezoidal flexible mechanism is diegned and optimized to reduce backward motion considering the influence of parasitic motion proportion. It applies the asymmetrical installation of the piezoelectric stack to increase parasitic motion hence the reducing of backward motion. This study discusses the structure and working process of piezoelectric actuators and optimizes the design of flexible mechanism structure parameters with matrix displacement method and finite element method. A prototype of an parasitic-inertia piezoelectric actuator was manufactured, and a series of experiments were conducted. From the experiment, the piezoelectric actuator obtained a minimum backward motion percentage α = 18.36% and forward motion time percentage β = 95.9% at the frequency f = 1 Hz and the voltage U = 80 V. At U = 120 V, f = 500 Hz, the maximum motion speed of the actuator is 916 μm s−1; At U = 20 V and f = 1 Hz, the minimum positioning resolution of the actuator is 0.69 μm. At U = 120 V, f = 1 Hz, the maximum vertical load force is 1600 g, and the maximum parallel load force is 50 g. It has shown that the proposed isosceles trapezoidal flexible mechanism is feasible and can significantly reduce backward motion at the appropriate voltage. The mentioned characteristics of isosceles trapezoidal flexible mechanism can significantly alleviate the abrasion of driving foot, improve working efficiency. Also, it is vital for the miniaturization and practical application of parasitic-inertia piezoelectric actuators.

Influence of Size and Orientation of 3D Printed Fiber on Mechanical Properties under Bending Stress

The principle of FFF/FDM (Fused Filament Fabrication/Fused Deposition Modeling) 3D printing technology is the melting and application of a continuous fiber made of thermoplastic material, according to predefined routes on the substrate. A layer is created on which other layers are placed until the object is finished. It is the orientation of these fibers that greatly affects the resulting mechanical properties. Therefore, the printed object behaves orthotropic. The material does not blend perfectly or evenly between the individual fibers, which is why the resulting strength is limited by adhesion. Within the fibers themselves, it is also its dimension that affects the size of the contact surface and therefore the effect of adhesion. This contribution aims to compare the effect of fiber size in a given direction and its rotation in 3-point bending according to the standard ČSN EN ISO 178. The maximum bending load force was obtained and the bending stress and modulus of elasticity were determined. The influence of layer cohesion on the failure of the specimens is compared. One of the other important studied aspects for the effective production is the printing time of each specimen.

Novel design of weld vector route for dissimilar nonferrous plates laser welding in battery manufacturing for electric vehicles

In this research, Al/Cu thicker plates are overlap-joined based on an experimental simulation to improve the metallurgical quality of laser welding the busbar tab to interconnect plate in manufacturing production for electric vehicle battery. The influence of weld vector route on the weld formation, microstructure and mechanical properties has been investigated via stereological microscope, metallographic microscope, material tensile testing machine, scanning electron microscope and energy dispersive spectroscope. Ductility-dip cracking (DDC) easily takes place along fusion zone migrated grain boundaries (MGBs) in local zones of brittle medium-concentrated IMC phases (AlCu+Al3Cu4) of the plain straight weld produced by conventional process, which leads to a maximum load force of only 915 N in tensile shear test. The designed Al/Cu laser welding with novel weld vector route could reduce the level of restraint in the weld metal and the degree of stress relaxation during reheating, which in turn prevents the occurrence of cracks. In tensile shear test, the dummy specimens have achieved an excellent performance with a maximum load force of 1380 N and a prominent plasticity owning a certain degree of dimple-like ductile fracture composition during deformation to break. This novel design of laser welding can successfully improve both the product quality and production efficiency for a green low-carbon manufacturing process, and concurrently reduce the time cost and energy consumption in rework process for nonconforming battery modules. Furthermore, from aspect of failure mode and effects analysis (FMEA), the novel process could enhance the safety and reliability of battery pack in physics and to refrain from potential failures resulting from thermal runaway, vibration, or impact due to pressure and dynamic mechanical loads when electric vehicles are running on the roads.

Evaluating Pull-Out Strength of Barbed Suture In Vitro by Using Porcine Tissue and Polydimethylsiloxane (PDMS).

Using barbed thread lifting for facial rejuvenation has become popular these days due to its minimally invasive procedures with reduced complications. However, only limited studies regarding its mechanical properties for face suspension were published. The aim of this study was to evaluate suture-holding ability regarding its facelift property, and different specimens were tested in order to establish an in vitro model. Fresh porcine tissue and the synthetic material polydimethylsiloxane (PDMS) were selected to simulate human skin for evaluating barbed suture pull-out strength by the universal material testing machine. The results showed that the pull-out strength of barbs between different porcine tissues varied without consistency. By contrast, PDMS (30:1) showed more consistent pull-out strength in each testing, and the average maximum load force was close to porcine tissue. Furthermore, after submerging barbed sutures in PBS for 0 days (T0), 7 days (T7) and 14 days (T14), a trend of decreased average maximum load force, displacement and force of 1.5 mm/2 mm/3 mm displacement could be detected by in vitro testing with PDMS (30:1). These results provide support for using PDMS (30:1) to evaluate suture pull-out strength and holding/lifting capacities in vitro to obtain consistent and objective information for evaluating substantial equivalence of devices. The established in vitro method could be used for the future development of barbed thread lifting technology.

МЕТОДИКА ПРОЄКТНОГО РОЗРАХУНКУ ЕЛЕКТРОГІДРАВЛІЧНОГО СЛІДКУЮЧОГО ПРИВОДА ТЕХНОЛОГІЧНОГО ОБЛАДНАННЯ

Machine-building industries and enterprises for modernization of railway rolling stock are constantly increasing the requirements for the technical and functional characteristics of technological equipment drives. The improvement of equipment drives ensures the implementation of the optimal laws of working bodies motion, the accuracy of regulation of their movementsand the stability of speeds under variable load conditions, that has a direct impact on the quality of products and productivity.The use of automatic drives of technological equipment, in particular electrohydraulic servo drives, ensures the achievement of arbitrary kinematics of the working body and the possibility of software implementation of the optimal laws of its motion. The development of high-performance electrohydraulic servo drives and their implementation in specialized technological equipment is a rather labor-intensive process and requires the use of engineering methods of project calculation that make it possible to evaluate the main parameters, select drive elements and devices, and predict its static and dynamic characteristics.Currently, there are separate methods and procedures for designing of automatic electro-hydraulic drives for various technological equipment for mechanical processing, in particular equipment for processing materials by pressure, metal-cut-ting machine tools and systems, tool equipment, etc. The available methods are not universal, as a rule they are focused on different classes of both conventional and specialized equipment, they use different initial data, apply various calculation methods and, as a result, have incompatible calculation results.The continuous improvement of the technological equipment of modern machine-building industries and enterprises for the modernization of rolling stock of railways requires the creation of generally accepted engineering methods of project calculation of electrohydraulic servo drives of technological equipment. Based on the works of the authors by design of automatic drives of technological equipment, mathematical modeling and research of their static and dynamic characteristics, as well as correction of the quality ofregulation, a unified engineering method for the design calculation of servo electrohydraulic drives is proposed.The work is devoted to the development of an engineering methodology for the project calculation of an electrohydraulic servo drive with a throttle adjustment of technological equipment, which makes it possible to evaluate the main parameters, select drive elements and devices, and predict its static and dynamic characteristics.An engineering methodology of project calculation of an electrohydraulic servo drive with throttle control for specialized tech-nological equipment of machine-building industries and enterprises for the modernization and repair of rolling stock of railways is presented. The application of engineering methodology involves setting of the following initial data: maximum load (force); maximum tracking speed without load; maximum tracking error (or allowable tracking error at maximum speed); piston stroke; the mass of moving elements. According to the methodology the calculations are made in the following order: design of a drive scheme, selection of a working fluid and nominal working pressure; calculation of design parameters and selection of a hydraulic cylinder; choice of electrohydraulic amplifier; determination of feedbackparameters, determination of the quality factor of the drive and calculation of the transmission coefficient of electrical unit; assessment of drive static characteristics, calculation of speed and load characteristics; designing of drive linear model; durability assessment; study of drive dynamic characteristics and the quality of regulation; drive correction. An example of a project calculation of an electrohydraulic servo drive of specialized pressure processing equipment for a maximum force of 160 kN and a maximum tracking speed without load of 0,05 m/s is given. The results of calculations of the static and dynamic characteristics of the drive using the MATLAB application package are presented.An engineering method for project calculation of an electrohydraulic servo drive for specialized technological equipment is proposed. An example of a project calculation of an electrohydraulic servo drive of specialized technological equipment is given.

A walking type piezoelectric actuator based on the parasitic motion of obliquely assembled PZT stacks

In order to decrease the backward motion and improve the motion efficiency, a walking type piezoelectric actuator has been proposed with two ‘legs’ based on the parasitic motion of obliquely assembled PZT stacks. The structure and motion principle of the proposed walking type piezoelectric actuator are described, and its experiment system is set up. Experimental results indicate the proposed piezoelectric actuator could reduce the backward motion effectively. The minimum backward rate α= 2.26% is achieved under the condition of the phase difference θ= 180°, the input voltage U= 120 V and the input frequency f= 1 Hz; the minimum stepping displacement is 0.24 μm under the condition of U= 5 V, f= 1 Hz and θ= 180°; the maximum speed V max is 2472 μm s−1 under the condition of U =120 V and θ= 180°; the maximum vertical load force F Vmax = 6850 g under the condition of U = 120 V, f = 1 Hz and θ = 180°. Furthermore, a dynamic model of the whole walking type piezoelectric actuator is established, and it has been employed to simulate the motion of the proposed walking type piezoelectric actuator. Simulation results present a great agreement of experimental results. This study shows a novel idea for the design of piezoelectric actuators to eliminate the influence of backward motion and improve the output efficiency of the actuator.

Anticipation and compensation for somatosensory deficits in object handling: evidence from a patient with large fiber sensory neuropathy.

The purpose of this study was to determine the contributions of feedforward and feedback processes on grip force regulation and object orientation during functional manipulation tasks. One patient with massive somatosensory loss resulting from large fiber sensory neuropathy and 10 control participants were recruited. Three experiments were conducted: 1) perturbation to static holding; 2) discrete vertical movement; and 3) functional grasp and place. The availability of visual feedback was also manipulated to assess the nature of compensatory mechanisms. Results from experiment 1 indicated that both the deafferented patient and controls used anticipatory grip force adjustments before self-induced perturbation to static holding. The patient exhibited increased grip response time, but the magnitude of grip force adjustments remained correlated with perturbation forces in the self-induced and external perturbation conditions. In experiment 2, the patient applied peak grip force substantially in advance of maximum load force. Unlike controls, the patient's ability to regulate object orientation was impaired without visual feedback. In experiment 3, the duration of unloading, transport, and release phases were longer for the patient, with increased deviation of object orientation at phase transitions. These findings show that the deafferented patient uses distinct modes of anticipatory control according to task constraints and that responses to perturbations are mediated by alternative afferent information. The loss of somatosensory feedback thus appears to impair control of object orientation, whereas variation in the temporal organization of functional tasks may reflect strategies to mitigate object instability associated with changes in movement dynamics.NEW & NOTEWORTHY This study evaluates the effects of sensory neuropathy on the scaling and timing of grip force adjustments across different object handling tasks (i.e., holding, vertical movement, grasping, and placement). In particular, these results illustrate how novel anticipatory and online control processes emerge to compensate for the loss of somatosensory feedback. In addition, we provide new evidence on the role of somatosensory feedback for regulating object orientation during functional prehensile movement.

Undulating compression and multistage relaxation in a granular column consisting of dust particles or glass beads

For fundamentally characterizing the effect of hierarchical structure in granular matter, a set of compression-relaxation tests for dust particles and glass beads confined in a cylindrical cell was performed. Typical diameter of both grains is approximately 1~mm. However, dust particles are produced by binding tiny ($\sim 5$~{\textmu}m) glass beads. The granular columns were compressed with a piston until reaching a maximum load force of 20~N with a constant compression rate $v$ ($0.17 \leq v \leq 2000$~{\textmu}m~s$^{-1}$). After that, the piston was stopped and the relaxation process was quantified. From the experimental results, we found that the compression force $F$ nonlinearly increases with the increase of compression stroke $z$ depending on particles. Besides, periodic undulation and sudden force drops were observed on $F(z)$ in dust particles and glass beads, respectively. The relaxation process was characterized by an exponential decay of stress followed by a logarithmic dependence one in both kinds of particles. These experimental findings are the main point in this study. To understand the underlying physics governing the compression mechanics, we assumed empirical forms of $F(z)$; $F\propto z^{\alpha}$ for dust particles and $F \propto \exp(z/z_G)$ for glass beads ($\alpha=2.4$ and $z_G=70$~{\textmu}m). Then, we found that the growing manners of periodic undulation and force drops were identical to those of mean compression forces, i.e., power law in dust particles and exponential in glass beads. In addition, the undulation amplitude and wavelength decreased as $v$ increased in dust-particles compression. On the basis of experimental results and the difference between dust particles and glass beads, we also discuss the origin of undulation and the physical meaning of granular-compression models used in engineering fields.

Biological Mechanism of Extracorporeal Shock Wave Combined with Platelet-Rich Plasma on the Healing of Reconstructed Tendon Bone in a Rabbit Model of Rotator Cuff Tear

To investigate the biological mechanism of the effect of extracorporeal shock wave combined with plateletrich plasma on the healing of reconstructed tendon bone in a rabbit model of rotator cuff tear. 40 New Zealand white rabbits aged 4-5 mo were selected, 32 rabbits were randomly selected and each rabbit was executed at 4-8 w postoperatively and these rabbits were randomly divided into control group, shockwave group, platelet-rich plasma group and shockwave+platelet-rich plasma group. The tendon bone healing site was observed at 2, 4 and 8 w after surgery and the content of transforming growth factor beta 1 and basic fibroblast growth factor were measured by reverse transcription-polymerase chain reaction and western blot, while the biomechanical test was performed on the tendon bone healing specimens. The results showed that the content of neovascularization at the tendon-bone interface at 4 w and 8 w was significantly increased in shockwave, platelet-rich plasma and shockwave+platelet-rich plasma groups. The basic fibroblast growth factor and transforming growth factor beta 1 messenger RNA and protein expression tended to increase after surgery in all four groups and the levels in shockwave, plateletrich plasma and shockwave+platelet-rich plasma groups was significantly increased, while the highest expression in shockwave+platelet-rich plasma group. The maximum load force of the 3 experiment groups was all significantly increased. Besides, the maximum tensile distance was significantly longer in shockwave+platelet-rich plasma group. The combination of extracorporeal shockwave and plateletrich plasma showed optimal performance in the tensile performance of the supraspinatus tendon-bone combination, the maturity of the tendon-bone interface and the content of growth factors that promote the healing of the tendon bone, indicating that the combination of extracorporeal shock wave and plateletrich plasma can promote the healing process of the tendon bone after rotator cuff tears and improve its strength and ultimate load.

The Effect of Allogenic Bone Marrow on Integration Dev-Mesenchymal Stem Cell And Vascular Endothelial Growth Factor

Background: The integration of the tendon graft within the bone tunnel is one of the decisive success factors of the Anterior Cruciate Ligament (ACL) reconstruction. In ACL reconstruction that uses tendons as graft, the healing process that occurs in the bone tunnel is healing with fibrotic tissue. Aim: This study aims to determine the role of bone marrow mesenchymal stem cells and vascular endothelial growth factor intraarticularly in improving the biomechanical strength. Methods: This study uses experimental research design by using animal as a testing tool. The animals used in this study are male New Zealand white rabbits (Oryctolagus cuniculus), with the weight ranging of 2000 grams up to 3000 grams. Results: From the experiment, all samples from both treatment and control groups were all evaluated and no post-operative complication was found. At the evaluation time of 3 weeks, the difference between the mean of maximum strain rate between the treatment group and the control group was not statistically significant (p >0.05). At the evaluation time of 6 weeks, it was found that the difference in mean value of the maximum strain load force between the treatment groups versus the group was statistically significant. Conclusions: From this study, it can be concluded that intraarticular BM-MSC and VEGF administration can increase the ultimate tension strength of postoperative graft tendon rosary ACL reconstruction.

Fabrication, Mechanical Modeling, and Experiments of a 3D-Motion Soft Actuator for Flexible Sensing

This paper introduces the modular design and manufacturing method, mechanical model, and test verification of a new type of soft actuator driven by fluid. First, the modular design scheme and driving principle of omnidirectional bending and elongation of the soft actuator are described. Three print-based elastic air cavities constrained by fire lines are distributed radially inside the actuator. The actuator can complete the 3 DOF motions of omnidirectional bending and elongation. From the basic principle of material mechanics, a novel mechanical model of the soft elastomer actuator is established. By numerically solving the nonlinear model, the relationship between actuator elongation/bending angle and driving pressure is obtained. The theoretical prediction and test results show that the deformation of the actuator exhibits a linear relationship with pressure when the chambers are charged. Additionally, the maximum allowable load force on the actuator terminal also exhibits good linearity when the driving pressure increases. Furthermore, the established mechanical model, which considers gravity effects can more accurately describe the features of bend and elongation of the actuator. The results shows that the proposed model is more convenient than the FEM models. This study provides theoretical support for accurate control of a soft actuator.

In vitro retention efficiency of temporary type zinc oxide cement for orthodontic forced eruption

To assess the retention efficiency of three types of temporary zinc oxide cement trademarks on forced eruption using intracranal wire device. An in vitro evaluation included intracanal wire device displacement and detachment at 50g load force for 120 days and then the retention resistance at maximum load force. All groups of temporary zinc oxide cements were efficient to support 50g load forces after 120 days. None statistical differences were found between groups. Zinc oxide cements supported a maximum retention load force, which exceeded in more than 84 times the lowest value obtained in controls (420g). Zinc oxide cements are efficient to retain intracanal wire devices on forced eruption processes in vitro and allows removal of both when necessary (wire device and cement, respectively).

Analysis of the effect of structural defects on the fatigue strength of RFSSW joints using C‐scan scanning acoustic microscopy and SEM

AbstractSolid‐state refill friction stir spot welding (RFSSW) technology offers significant benefits in the fabrication of aluminium structures in the transport and aerospace industries. In this paper, the joining of 1.6‐mm‐thick Alclad 7075‐T6 aluminium alloy sheets is investigated. High‐cycle fatigue strength tests of single‐lap welded joints were carried out on an Instron E10000 testing machine with a limited number of cycles equal to 2 × 106. The welding of overlap fatigue specimens was conducted using an RPS100 spot welder by Harms & Wende GmbH & Co KG. C‐mode scanning acoustic microscopy (C‐SAM) and scanning electron microscopy (SEM) were utilised to evaluate the joint quality and characterise the microstructure. The paper discusses the effect of the maximum load force and defects (voids, hook, kissing bond, bonding ligament, etc) associated with the material flow in the weld on the failure mechanism. Insufficient plasticisation of sheet material and mixing of the material in the weld area are crucial defects that influence the number of destructive cycles. The weld defects in the joint structure are a source of a decrease in the fatigue life compared with the fatigue life of defect‐free welds. It was also found that RFSSW joint defects can be effectively detected by the nondestructive C‐SAM method.

Effects of the Surface Texture and Weight of a Pinch Apparatus on the Reliability and Validity of a Hand Sensorimotor Control Assessment

ObjectivesTo investigate the reliability and validity of a modified pinch apparatus devised with 3 surface textures and 2 different weights for clinical application. DesignCase-controlled study. SettingA university hospital. ParticipantsThe participants (N=32) included carpal tunnel syndrome (CTS) patients (n=16) with 20 sensory neuropathy hands, and an equal number of age-sex matched volunteers without CTS, as well as young volunteers without CTS (n=16 with 20 hands) used to analyze both the testing validity and reliability of the modified device. InterventionsNot applicable. Main Outcome MeasuresThe Semmes-Weinstein monofilament (SWM) and two-point discrimination (2PD) tests were conducted, and the force ratio between the FPpeak (peak pinch force during lifting phase) and FLmax (maximum load force at maximum upward acceleration onset) detected from a pinch-holding-up activity (PHUA) under various testing conditions was obtained. ResultsThe range of the intraclass correlation coefficient of this pinch device was 0.369-0.952. The CTS patients exhibited poorer force modulation ability according to the inertial change in a dynamic lifting task when compared to the controls under all testing conditions (P<.001). The area under the receiver operating characteristic force ratio curve was 0.841, revealing high accuracy of the test for diagnosing CTS neuropathic hands under the testing condition in which the 125-g coarse texture device was used. In addition, the weight factor was shown to have significant effects on the sensitivity and accuracy of the PHUA assessment. ConclusionsThis study showed that the PHUA test via the modified pinch apparatus is a sensitive tool that can be used in clinical practice for detecting neuropathic CTS hands. In addition, changing the weight of the pinch device has a significant effect on the sensitivity and accuracy of the PHUA assessment.

Arc characteristics and droplet transfer process in CMT welding with a magnetic field

Al6061-T6 and TC4 alloys were successfully joined via an external axial magnetic field hybrid cold metal transfer process. The visual sensing of arc behavior and droplet transfer process based on high-speed camera method has been adopted in an attempt to investigate the study of the welding process under magnetic field. The results showed that both the weld arc and the droplet transfer process were modified by the magnetic field. The charged particles exhibited a spiral motion and the weld arc changed to rotating bell shape. The droplet rotated around the wire and the spray transfer process was restrained with the application of magnetic field. Furthermore, the magnetic field could increase the spreading ability of molten pool. The temperature and holding time at the interface decreased, suppressing the growth behavior of brittle intermetallic compounds at the weld/Ti interface. The thickness of the intermetallic layer decreased from 9.7 μm in the normal welding process to 1.8 μm with a magnetic field. The maximum tensile shear load force of 4.21 kN was obtained and the fracture occurred at the heat affected zone of Al side.

Repair of segmental bone defects in rabbits' radius with domestic porous tantalum encapsulated with pedicled fascial flap

To investigate the effect of domestic porous tantalum encapsulated with pedicled fascial flap on repairing of segmental bone defect in rabbits' radius. A total of 60 New Zealand white rabbits (aged 6- 8 months and weighing 2.5-3.0 kg) were randomly divided into the experimental group and control group (30 rabbits each group). A 1.5 cm segmental bone defect in right radius was established as the animal model. The porous tantalums encapsulated with pedicled fascial flaps (30 mm×20 mm) were implanted in the created bone defect in the experimental group, and the porous tantalums were only implanted in the control group. X-ray films were observed at the day after operation and at 4, 8, and 16 weeks after operation. Specimens were taken out at 4, 8, and 16 weeks after operation for HE staining and toluidine blue staining observation. The maximum load force and bending strength were detected by three point bending biomechanical test, and the Micro-CT analysis and quantitative analysis of the new bone volume fraction (BV/TV) were performed at 16 weeks after operation to compare the bone defect repair ability in vivo in 2 groups. All incisions healed by first intention without wound infection. At 4, 8, and 16 weeks after operation, the X-ray films showed that the implants were well maintained without apparent displacement. As followed with time, the combination between the implants and host bone became more and more closely, and the fracture line gradually disappeared. HE staining and toluidine blue staining showed that new bone mass and maturity gradually increased at the interface and inside materials in 2 groups, and the new bone gradually growed from the interface to internal pore. At 16 weeks after operation, the three point bending biomechanical test showed that the maximum load force and bending strength in the experimental were (96.54±7.21) N and (91.26±1.76) MPa respectively, showing significant differences when compared with the control group [(82.65±5.65) N and (78.53±1.16) MPa respectively] ( t=3.715, P=0.004; t=14.801, P=0.000). And Micro-CT analysis exhibited that there were a large amount of new bone at the interface and the surface of implant materials and inside the materials. The new bone BV/TV in the experimental group (32.63%±3.56%) was significantly higher than that in control group (25.07%±4.34%) ( t=3.299, P=0.008). Domestic porous tantalum encapsulated with pedicled fascial flap can increase local blood supply, strengthen material bone conduction ability, and promote the segmental bone defect repair.