Radial Compression Research Articles

Is radial artery occlusion and local vascular complications following transradial coronary procedures affected by the type of haemostasis device used? A non-inferiority Randomized Controlled Trial (RadCom trial).

Vascular access site complications following transradial coronary procedures are less common and severe compared to femoral approach. Radial artery occlusion is considered the main adverse effect. As radial access is gaining more acknowledgement, complication awareness, and understanding is important. The aim was to assess complication rates following transradial coronary procedures and to compare two radial compression devices in a non-inferiority randomized controlled trial. Four hundred and ninety-nine patients were randomized to radial compression with a new device (RY Stop, n = 248) or the reference device (TR Band, n = 251) following transradial coronary procedures. Radial artery occlusion persistent at 90 days was the primary endpoint. Discomfort and accounts of vascular complications at access site were secondary endpoints. Radial artery occlusion was observed in 5% (n = 26) for the entire cohort with no difference between groups (RY Stop 6% vs. TR Band 5%; P = 0.69). Patients overall reported low levels of discomfort and the median scores were similar in both groups; RY Stop: 7 vs. TR Band: 10 (P = 0.90). There were few incidents of bleeding (7%), however, they were significantly more frequent with the RY Stop (12%) than with the TR Band (3%; P = 0.001). Few patients (4%) developed access site haematomas, and the incidence was similar in the two groups (P = 0.98). We observed a radial artery occlusion rate of 5% at 90 days post-procedure. Access site discomfort and vascular complication rates were low. Overall, the RY Stop compression device was not inferior to the TR Band except occurrences of bleeding.

The Mechanical Investigation of Filament-Wound CFRP Structures Subjected to Different Cooling Rates in Terms of Compressive Loading and Residual Stresses-An Experimental Approach.

Although cooling at ambient temperature is widely used and is said to be safe and convenient, faster cooling may have an influence not only on the time of the manufacturing process but also on the mechanical response, especially the residual stress. The study aimed to investigate the influence of the cooling rate after curing on the mechanical response of filament-wound thick-walled carbon fiber reinforced polymer (CFRP) rings. Three cooling rates were taking into consideration: cooling with the oven, at room temperature, and in the water at 20 °C. The splitting method was used to examine the residual strains. In the radial compression test, the mechanical response was investigated between the rings with different cooling regimes. The FEM analysis of the compression test in elastic range was also performed. Both the splitting method and the radial compression test showed no significant difference in the mechanical response of the CFRP rings. The presented results showed that the fast-cooling rate slightly decreases the mechanical performance of the filament-wound rings.

Axial and Radial Compression Behavior of Composite Rocket Launcher Developed by Robotized Filament Winding: Simulation and Experimental Validation.

The principal objective of the work is to compare among carbon-glass filament wound epoxy matrix hybrid composites with a different fiber ratio made by robotized winding processes and optimize the geometry suitable for the Rocket Propelled Grenade Launcher. ANSYS based finite element analysis was used to predict the axial as well as radial compression behavior. Experimental samples were developed by a robot-controlled filament winding process that was incorporated with continuous resin impregnation. The experimental samples were evaluated for the corresponding compressional properties. Filament wound tubular composite structures were developed by changing the sequence of stacking of hoop layers and helical layers, and also by changing the angle of wind of the helical layers while keeping the sequence constant. The samples were developed from carbon and glass filaments with different carbon proportions (0%, 25%, 50%, 75%, and 100%) and impregnated with epoxy resin. The compressional properties of the tubular composites that were prepared by filament winding were compared with the predicted axial and radial compressional properties from computational modelling using the finite element model. A very high correlation and relatively small prediction error was obtained.

Study on Mechanical Properties and Failure Mechanism of Axial Braided C/C Composite

In order to study the mechanical properties and failure mechanism of the axial braided C/C composites, the microscopic and macroscopic mechanical properties of the composite were investigated. In view of the size effect of the samples, the properties of the samples with different thickness were tested. The strain during loading was measured by optical method, and the failure morphology was observed by SEM. The changing characteristics of stress-strain curve were analyzed, and the failure characteristics of materials and failure mechanism under various loads were obtained. It was found that brittle fracture was observed during the tensile process of axial braided C/C composites, and the main failure forms were fiber rod pulling and partial fiber rod breaking in the axial direction. Radial failure was mainly in the form of fiber bundle fracture and crack stratification propagation. When compressed, the material exhibited pseudoplastic characteristics. The radial compression sample was cut along a 45-degree bevel. The axial compression curve was in the form of double fold, the axial fiber rod was unstable, and the transverse fiber bundle was cut. During in-plane shearing, the axial fracture was brittle and the fiber rod was cut. The radial direction showed the fracture and pulling of the fiber bundle, and the material had the characteristics of pseudoplasticity. The research methods and results in this paper could provide important references for the optimization and rational application of C/C composite materials.

A flexible porous chiral auxetic tracheal stent with ciliated epithelium

Tracheal stent placement is a principal treatment for tracheobronchial stenosis, but complications such as mucus plugging, secondary stenosis, migration, and strong foreign body sensation remain unavoidable challenges. In this study, we designed a flexible porous chiral tracheal stent intended to reduce or overcome these complications. The stent was innovatively designed with a flexible tetrachiral and anti-tetrachiral hybrid structure as the frame and hollows filled with porous silicone sponge. Detailed finite element analysis (FEA) showed that the designed frame can maintain a Poisson's ratio that is negative or close to zero at up to 50% tensile strain. This contributes to improved airway ventilation and better resistance to migration during physiological activities such as respiration and neck movement. The preparation process combined indirect 3D printing with gas foaming and particulate leaching methods to efficiently fabricate the stent. The stent was then subjected to uniaxial tension and local radial compression tests, which indicated that it not only has the same desirable auxetic performance but also has flexibility similar to the native trachea. The porous sponge facilitated the adhesion of cells, allowed nutrient diffusion, and would prevent the ingrowth of granulation tissue. Furthermore, a ciliated tracheal epithelium similar to that of the native trachea was differentiated from normal human bronchial primary epithelial cells on the internal wall of the stent under air-liquid interface conditions. These results suggest that the designed stent has the potential for application in the treatment of tracheobronchial stenosis.

Mechanical Assessment of Tissue Properties During Tourniquet Application.

Successful tourniquet application increases survival rate of exsanguinating extremity hemorrhage victims. Tactile feedback during tourniquet application training should reflect human tissue properties in order to increase success in the field. This study aims to understand the mechanical properties of a human limb during tourniquet application. Six cadaveric extremities-three uppers and three lowers-were tested from three body mass index groups: low (<19) healthy (19-24), and overweight (>24). Each specimen donned with a tourniquet and mounted to a servo-hydraulic testing machine, which enabled controlled tightening of the tourniquet while recording the tourniquet tension force and strap displacement. A thin-film pressure sensor placed between the specimen and the tourniquet recorded contact pressure. Each limb was tested with the tourniquet applied at two different sites resulting in testing at the upper arm, forearm, thigh, and shank. The load displacement curves during radial compression were found to be nonlinear overall, with identifiable linear regions. Average contact pressure under the tourniquet strap at 200N and 300N of tension force was 126.3 (σ = 41.2) mm Hg and 205.3 (σ = 75.3) mm Hg, respectively. There were no significant differences in tissue stiffness or contact pressure at 300N of tension force between limb (upper vs. lower) or body mass index. At 200N of tension, the upper limb had significantly higher contact pressure than the lower limb (P = 0.040). Relative radial compression was significantly different between upper (16.74, σ = 4.16%) and lower (10.15, σ = 2.25%) extremities at 200N tension (P = 0.005). Simulation of tissue compression during tourniquet application may be achieved with a material exhibiting elastic properties to mimic the force-displacement behavior seen in cadaveric tissue or with different layers of material. Different trainers for underweight, healthy, and overweight limbs may not be needed. Separate tourniquet training fixtures should be created for the upper and lower extremities.

Printable smart 3D architectures of regenerated silk on poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

In this study, we report the fabrication of two different three-dimensional (3D) architectures of regenerated silk (RS) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) with embedded functionalities. 3D printed cylinders with an internal layer of PHBV and an external of calcium ions (Ca++) or potassium nitrate (KNO3) modified RS were designed to control the radial shrinkage, water uptake and compression strength. Such cylinders were then used as sutureless thermoresponsive clips, measuring the bursting resistance once applied on an anastomized porcine intestine. Experimental data are supported by finite element simulations that model the tube contraction, demonstrating the possibility to program the shape-changing behavior of 3D printed structures. Printing RS on PHBV, we obtained responsive 3D grids to external force with self-powering properties. The synergic effect obtained by combining materials on appropriate architectures paves the way to potential clinical applications ranging from monitoring of vital signs to sutureless sealant patches.

Static and Flexural Fatigue Behavior of GFRP Pultruded Rebars.

This paper presents the experimental results of composite rebars based on GFRP manufactured by a pultrusion system. The bending and radial compression strength of rods was determined. The elastic modulus of GFRP rebars is significantly lower than for steel rebars, while the static flexural properties are higher. The microstructure of the selected rebars was studied and discussed in light of the obtained results—failure processes such as the delamination and fibers fracture can be observed. The bending fatigue test was performed under a constant load amplitude sinusoidal waveform. All rebars were subjected to fatigue tests under the R = 0.1 condition. As a result, the S-N curve was obtained, and basic fatigue characteristics were determined. The fatigue mechanism of bar failure under bending was further analyzed using SEM microscopy. It is worth noting that the failure and fracture mechanism plays a crucial role as a material quality indicator in the manufacturing process. The main mechanism of failure under static and cyclic loading during the bending test is widely discussed in this paper. The results obtained from fatigue tests encourage further analysis. The diametral compression test reflects the weakest nature of the composite materials based on the interlaminar compressive strength. The proposed methodology allows us to invariantly describe the experimental transversal strength of the composite materials. Considering the expected durability of the structure, the failure mechanism is likely to significantly improve their fatigue behavior under the influence of cyclic bending. The reasonable direction of searching for reinforcements of composite structures should be the improvement of the bearing capacity of the outer layers. In comparison with steel rebars (fatigue tensile test), the obtained results for GFRP are comparable in the HCF regime. It is worth noting that in the near fatigue endurance regime (2–5 × 106 cycles) both rebars exhibit similar behavior.

Silk reservoir implants for sustained drug delivery.

Biomaterial implants for the sustained delivery of therapeutics can be utilized to deliver drugs at near-constant rates over extended time frames to provide an alternative to daily oral medications. The biomaterials used to construct these systems, however, are often not bioresorbable and thus require a secondary surgery for removal from the body, and fabrication of these systems may require the use of harsh chemical solvents. To address these shortcomings, a fabrication process was developed to generate biodegradable drug reservoir systems from regenerated silk fibroin protein solution (23% w/v). The tubular systems, with an inner diameter of 2.0 mm and wall thickness < 250µm, were developed using an all-aqueous solution-gel-solid phase transition curing process. Two different clinically-relevant therapeutics were released at near-constant rates for 30 days (> 100µg/day). The protein secondary structure of the devices consisted of 40% crystalline beta sheet. Mechanically, radial compression (1mm/min) of unloaded systems demonstrated Young's moduli similar to cancellous (spongy) bone (100 to 250 MPa) and the systems showed good recovery under cyclic compression (to 17.5% strain). The devices could be generated in complex shapes (e.g., hollow cylinders) via an additive molding process, offering the potential for drug delivery but also for broader applications in tissue engineering and diagnostics.

Orchard biomass residues: Chemical composition, biological activity and wood characterization of apricot tree (Prunus armeniaca L.)

AbstractRecent EU directives have encouraged member states to follow circular economy guidelines on waste reuse, especially for waste originating from wood agro‐forest biomass. Delineating the antioxidant and chemical activity of biomass is a starting point to find new ways to utilize such materials. Here, an 8‐year‐old apricot (Prunus armeniaca L.) tree stand located in southern Italy was evaluated. First, dendrometric parameters (total volume, diameter, and height of trunk below the branches) and physical‐mechanical properties (density, total, tangential and radial shrinkage, moisture content, and compression strength) of timber collected from five experimental plots was evaluated. Bark and wood from apricot pruning were then subjected to different extraction techniques, in vitro antioxidant assays, and gas chromatographic studies to determine their antioxidant activity and their phytochemical composition. Bark had the highest antioxidant activity compared to wood. Several antioxidant compounds (e.g., scopoletin and naringenin) were detected in the samples, explaining the measured antioxidant activity. In conclusion, this study demonstrates the potential of using apricot extracts in nutraceutical, cosmeceutical, and industrial fields. © 2021 Society of Chemical Industry and John Wiley &amp; Sons, Ltd

Mechatronic System’s Permeable Materials with Controlled Porosity

Up-to-date directions in the development of modern industry increase the requirements for the quality of technical products. The design and manufacture of competitive process equipment require accuracy, productivity, and efficiency. Therefore, in this article, a new mechatronic system has been designed and developed to help porous, permeable materials with predicted porosity have been produced. The research aims to develop a mechatronic system for technology optimization in manufacturing permeable porous materials with controlled properties. As a result, the method of computer modeling of porous, permeable materials was developed. It allows us to consider the peculiarities of porosity distribution and radial velocity in radial isostatic compression. Additionally, a new mechatronic system for producing permeable materials allows us to determine the porosity distribution and particular characteristics of permeable powder material. The proposed approach allows us to evaluate the impact of technological modes on the main operational characteristics.

Printable Smart 3D Architectures of Regenerated Silk on Poly(3- Hydroxybutyrate-Co-3-Hydroxyvalerate)

In this study, we report the fabrication of two different three-dimensional (3D) architectures of regenerated silk (RS) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) with embedded functionalities. 3D printed cylinders with an internal layer of PHBV and an external of calcium ions (Ca++) or potassium nitrate (KNO3) modified RS were designed to control the radial shrinkage, water uptake and compression strength. Such cylinders were then used as sutureless thermoresponsive clips, measuring the bursting resistance once applied on an anastomized porcine intestine. Experimental data are supported by finite element simulations that model the tube contraction, demonstrating the possibility to program the shape-changing behavior of 3D printed structures. Printing RS on PHBV, we obtained responsive 3D grids to external force with self-powering properties. The synergic effect obtained by combining materials on appropriate architectures paves the way to potential clinical applications ranging from monitoring of vital signs to sutureless sealant patches.

Mathematical Modeling of Elastic Plastic Transitional Stresses in CNT-GS based Hybrid Nanocomposite Thin Walled Spherical Pressure Vessels

In this paper, an analytical solution is being provided for calculation of elastic plastic transitional stresses in Hybrid Nanocomposite made of Carbon Nano Tubes (CNT) and Graphene Sheets (GS) modeled in the form of thin walled Spherical shells, subjected to radial compression at the internal surface. The results are compared with a general use Carbon Nano Tubes based nanocomposite. The transition function given by Seth is being used to obtain the pressure at which the initial yielding takes place. The trends for radial and circumferential transitional stresses are obtained using the elastic stiffness constants obtained from young’s moduli, shear moduli and poisson’s ratios of the materials at the initial yielding and fully plastic state. The expressions for principal stresses are derived from the transition function considering the material anisotropy.

Electron transport properties of carbon nanotubes with radial compression deformation

研究径向压缩形变对碳纳米管电子输运性质的影响对搭建微纳碳基电子器件具有重要意义．本文利用分子动力学模拟方法研究了端部开口的碳纳米管与金属界面接触构型，得出碳纳米管径向压缩形变的规律．模拟结果表明：碳纳米管在水平地接触金属表面后，其稳定状态下的径向压缩形变大小会受接触长度、管径大小、金属种类和片层数量的影响．基于紧束缚密度泛函理论和非平衡格林函数结合的第一性原理，系统地研究了不同直径、手性、片层、径向形变碳纳米管的电子输运性质．研究表明：金属性单壁碳纳米管的电流呈线性增长趋势，且电流-电压的大小只与偏压有关，与直径大小无关；受到径向压缩形变时，电流在大偏压下增长趋势减缓，甚至会出现平台效应．半导体性单壁碳纳米管的导通电流随着径向压缩形变的增加而减小，电流-电压曲线逐渐从半导体特性向金属特性转变．随径向压缩形变的增加，双壁碳纳米管的电流-电压变化规律与金属性单壁碳纳米管的电流-电压曲线变化规律一致，但在相同偏压下，双壁碳纳米管的电流比单壁碳纳米管的电流高一倍；三壁碳纳米管的电流-电压曲线存在较大的震荡波动．

Creep and Residual Properties of Filament-Wound Composite Rings under Radial Compression in Harsh Environments.

This work focuses on the viscoelastic response of carbon/epoxy filament-wound composite rings under radial compressive loading in harsh environments. The composites are exposed to three hygro-thermo-mechanical conditions: (i) pure mechanical loading, (ii) mechanical loading in a wet environment and (iii) mechanical loading under hygrothermal conditioning at 40 C. Dedicated equipment was built to carry out the creep experiments. Quasi-static mechanical tests are performed before and after creep tests to evaluate the residual properties of the rings. The samples are tested in (i) radial compression, (ii) axial compression, and (iii) hoop tensile strength. Different laminates wound at off-axis orientations are manufactured via filament winding and analyzed. Key results show that creep displacement is affected by both hygrothermal and mechanical conditionings, especially at a higher temperature. Moreover, residual properties are quantified showing that creep generates permanent damage in the cylinders.

Radial nerve palsy following uncomplicated percutaneous nephrolithotomy

Injury to nerve is a well known complication of shoulder subluxation. Radial nerve injury is most commonly seen during percutaneous nephrolithotomy in lateral decubitus region. If the posterior aspect of the humerus is positioned incorrectly leads to radial nerve compression. Lateral decubitus position in percutaneous nephrolithotomy is the main position for posterior and lateral approaches. After percutaneous nephrolithotomy in lateral decubitus position reported the case of radial nerve palsy. A man of 26 year old from left (contralateral) percutaneous nephrolithotomy with signs of right radial nerve palsy on postoperative day number one. The body mass index is 28 &amp; underwent laterally attempted percutaneous nephrolithotomy on the left and he was located about 6 h and 30 min in the lateral decubitus position. Orthopedics, physiotherapy and electromyography were done to treat radial nerve palsy in the post-operative period. It demonstrates complication of the radial nerve palsy which may be related with percutaneous nephrolithotomy. Being aware of the complication can be used to stop pressure points at percutaneous nephrolithotomy in the lateral decubitus position.

Nerve Response to Superelastic Shape Memory Polyurethane Aerogels.

We have previously shown the suitability of aerogels as scaffolds for neuronal cells. Here, we report on the use of superelastic shape memory polyurethane aerogels (SSMPA). SSMPA have a distinctly different stiffness than previously reported aerogels. The soft and deformable nature of SSMPA allowed for radial compression of the aerogel induced by a custom designed apparatus. This radial compression changed the pore diameter and surface roughness (Sa) of SSMPA, while maintaining similar stiffness. Two varieties of SSMPA were used, Mix-14 and Mix-18, with distinctly different pore diameters and Sa. Radial compression led to a decreased pore diameter, which, in turn, decreased the Sa. The use of custom designed apparatus and two types of SSMPA allowed us to examine the influence of stiffness, pore size, and Sa on the extension of processes (neurites) by PC12 neuronal cells. PC12 cells plated on SSMPA with a higher degree of radial compression extended fewer neurites per cell when compared to other groups. However, the average length of the neurites was significantly longer when compared to the unrestricted group and to those extended by cells plated on SSMPA with less radial compression. These results demonstrate that SSMPA with 1.9 µm pore diameter, 1.17 µm Sa, and 203 kPa stiffness provides the optimum combination of physical parameters for nerve regeneration.

In vitro and in silico testing of partially and fully bioresorbable vascular scaffold

Coronary artery disease (CAD), one of the leading causes of death globally, occurs due to the growth of atherosclerotic plaques in the coronary arteries, causing lesions which restrict the flow of blood to the myocardium. Percutaneous transluminal coronary angioplasty (PTCA), including balloon angioplasty and coronary stent deployment is a standard clinical invasive treatment for CAD. Coronary stents are delivered using a balloon catheter inserted across the lesion. The balloon is inflated to a nominal pressure, opening the occluded artery, deploying the stent and improving the flow of blood to the myocardium.All stent manufacturers have to perform standard in vitro mechanical testing under different physiological conditions. In this study, partially and fully bioresorbable vascular scaffolds (BVS) from Boston Scientific Limited have been examined in vitro and in silico for three different test methods: inflation, radial compression and crush resistance.We formulated a material model for poly-L-lactic acid (PLLA) and implemented it into our in-house software tool. A comparison of the different experimental results is presented in the form of graphs showing displacement-force curves, diameter – load curves or diameter - pressure curves. There is a strong correlation between simulation and real experiments with a coefficient of determination (R2) > 0.99 and a correlation coefficient (R) > 0.99.This preliminary study has shown that in-silico tests can mimic the applicable ISO standards for mechanical in vitro stent testing, providing the opportunity to use data generated using in-silico testing to partially or fully replacing the mechanical testing required for regulatory submission.

Combination of InnoSEAL plus TR band compared with TR band alone for radial artery outcomes in patients undergoing transradial coronary intervention (InnoSEAL-II): an open-label randomised controlled trial (protocol)

IntroductionAbout 2%–30% of cardiac catheterisation procedures get complicated by radial artery occlusion (RAO). Ensuring patent haemostasis appears to be an important factor in reducing RAO. Currently employed method is a...

Effects of constraint between filaments on the radial compression properties of poly (l-lactic acid) self-expandable braided stents

With the application of bioresorbable materials in self-expandable braided stent, current analytical model for radial compression property of the stent is not applicative if considering the constraint between the polymeric filaments. Poly (l-lactic acid) (PLLA) is one of the broadly used bioresorbable materials in stents due to its superior biocompatibility and mechanical properties. The radial compression properties of PLLA braided stents were investigated by considering two types of constraints between filaments in this work. Weak constraint indicates the friction between filaments of PLLA stents and strong constraint indicates the close looped end (extremity configuration) of PLLA stents. It is found that the radial stiffness can be enhanced by two types of constraints, and strong constraint improves the peak compression force slightly in the radial compression behavior of PLLA braided stents. This work provides suggestions for the study of PLLA braided stents theoretical development.