Multiple Rods Research Articles

182. Catastrophic acute failure of pelvic fixation in adult spinal deformity requiring revision surgery: a multicenter review of incidence, failure mechanisms, and risk factors

182. Catastrophic acute failure of pelvic fixation in adult spinal deformity requiring revision surgery: a multicenter review of incidence, failure mechanisms, and risk factors

236. Rod failures continue to plague the surgical treatment of adult spinal deformity (ASD)

<h3>BACKGROUND CONTEXT</h3> Rod failure and pseudarthrosis are common complications following the surgical treatment of adult spinal defomity (ASD). Many strategies have been employed in mitigating these problems, such as interbody fusion, multiple rods, use of more effective biologics, and optimizing spinal alignment. We aimed to study the frequency and type of rod failures in a large ASD population over time. <h3>PURPOSE</h3> To study the frequency and type of rod failures in a large ASD population over time. <h3>STUDY DESIGN/SETTING</h3> Retrospective review of prospective data. <h3>PATIENT SAMPLE</h3> This study included 647 adult spinal deformity patients surgically treated between 2008 and 2018. <h3>OUTCOME MEASURES</h3> Rod failures. <h3>METHODS</h3> ASD patients with a fusion extended from minimum L1 to pelvis and min 2-year follow-up were included. Radiographs and records were examined to identify characteristics of the rod failures: timing, unilateral vs bilateral, vertebral level, unilateral progressing to bilateral failure, revision and failure rates over time. <h3>RESULTS</h3> Among the study population, 647/1052 patients met inclusion criteria (age: 64±10 yrs., 78% F, BMI: 28.3±5.7, Mean follow-up: 37 months ±13). Surgeries for these patients were performed from 2008 to 2018. The UIV was T7 or above in 306 and T8 or below in 338 patients, most frequent UIV: T4 (121) and T10 (208). A total of 146 patients had a 3COs; 435 had interbody fusion with 187 ALIF, 202 TLIF,135 XLIF; 286 patients had BMP use post only and 203 had BMP use interbody and posteriorly. Overall rod failure rate was 135/647 (21%), of which 9.3% occurred before by 2 years postop. Mean days to failure was 795 day +/- 485 (Median 733). Most frequent failures were in the lower lumbar spine L3-4 (32) 24%, L4-5 (34) 25% and L5-S1 (44) 32%. Of the 97 Unilateral failures, 35 (36.1%) were revised and only 8 progressed to bilateral failure of which 6/8 were revised; 46 Bilateral failure, 24 (52.2%) were revised.Kaplan-Meier analysis shows a survival rate of 89.7% at 2 years with decrease of 5% per year. No significant difference was found between the first 5 years and last 5 years. Comparison of primary vs revision index procedures did not reveal any differences in time to failure nor time to revision. Use of BMP improved survival rate to 91.2% compared to no BMP 83.4% at 2 years. <h3>CONCLUSIONS</h3> Rod failures remain a common complication when treating ASD with a rate of 21%. Among those rod failures, 9.3% occurred within 2 years. The most frequent sites of failure were in the lower lumbar spine. Unilateral failures underwent a lower rate of revision than bilateral. BMP increased rod survivability. Kaplan-Meier analysis demonstrated a survival rate of 89.7% at 2 years with a decrease of 5% per year. The failure rate has not improved when comparing the first 5 years. to last 5 years. We must continue to seek solutions to improve rod durability challenges to improve long-term outcomes. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

P92. Compared to multi rod (≥3) constructs, interbody fusion does not reduce the rate of rod failure at 2-year minimum follow-up

<h3>BACKGROUND CONTEXT</h3> Pseudarthrosis with distal mechanical failure is a common complication after long constructs in adult spinal deformity (ASD). Multiple strategies have been proposed to improve fusion rates and reduce the rate of rod fracture, including the use of interbody fusion (IBF) and multi-rod (≥3) techniques. Whether rod fracture rates are lower with the utilization of IBF versus multi-rod constructs remains unknown. <h3>PURPOSE</h3> To assess for any difference in rod fracture rate between constructs with IBF and multiple rods up to 2 years postoperatively. <h3>STUDY DESIGN/SETTING</h3> Retrospective Cohort. <h3>PATIENT SAMPLE</h3> ASD patients undergoing fusion of ≥6 levels to ilium and a minimum follow-up of 24 months. <h3>OUTCOME MEASURES</h3> Rate of postoperative rod fracture. <h3>METHODS</h3> ASD patients undergoing fusion of ≥6 levels to ilium and a minimum follow-up of 24 months were included. Patients with a history of prior fusion to L4 or below, and those with neuromuscular disease, inflammatory arthritis, or skeletal dysplasia were excluded. Patients were grouped by construct types: 2 rods w/ IBF (IBF) and w/o IBF (2R) and ≥3 rods w/o IBF (3R). Demographics, perioperative and radiographic data, and evidence of rod fracture were collected. ANOVA, chi-square and Fisher exact tests were used to compare across construct types. <h3>RESULTS</h3> Seventy-one patients were included, with mean age 65.0 years (±8.5) and BMI 26.7 kg/m2 (±5.4). In total, 20 patients had 2R constructs, 12 had IBF, and 39 had 3R. There were no significant differences in sagittal or coronal parameters at baseline or 2 years, or in OR time, EBL, or number of levels fused across groups. There were 76.1% of patients with posterior column osteotomy (2R 75.0%, IBF 50.0%, 3R 84.6%; p=0.063) and 9.9% had 3 column osteotomy. There were 12 total rod fractures (15.2%) with no significant difference between groups (2R 25.0%, IBF 16.7%, 3R 12.8%; p=0.423) and no differences in revision rate for rod fracture. <h3>CONCLUSIONS</h3> Compared to multi-rod techniques, the addition of IBF does not reduce the rate of rod fracture at two years after long constructs for ASD. These findings suggest that increasing the rigidity of the construct with the addition of a third rod may be sufficient to prevent rod fractures while IBF may provide no additional benefit at 2 years follow-up. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

216. Does interbody fusion at L4-L5 and L5-S1 lead to a lower rate of revision surgery for pseudarthrosis and rod fracture at the lumbosacral junction?

<h3>BACKGROUND CONTEXT</h3> Pseudarthrosis and rod fracture at the lumbosacral junction can lead to pain and loss of deformity correction requiring complex revision surgery. Multiple rods spanning the lumbosacral junction and interbody fusion may minimize the risk for pseudarthrosis and instrumentation failure. It remains unclear if interbody fusion at the caudal levels of a long fusion reduces long-term complications. <h3>PURPOSE</h3> To evaluate rates of revision for pseudarthrosis and rod fracture with interbody fusion at L4-L5 and L5-S1, compared to PSF only in long fusion constructs for adult spinal deformity (ASD) surgery. <h3>STUDY DESIGN/SETTING</h3> Retrospective review of prospectively collected single center database. <h3>PATIENT SAMPLE</h3> This study included 367 ASD patients (age: 58 ± 16 y; mFI: .6 ± .7; levels fused: 10.1 ± 4.8) with mean follow-up 68.1 months. <h3>OUTCOME MEASURES</h3> Outcomes evaluated were the rates of revision surgery for pseudarthrosis or rod fracture at the lumbosacral junction. <h3>METHODS</h3> A total of 367 ASD patients were divided into two groups: PSF only (PSF, n=192), and ALIF or TLIF (interbody fusion [IBF], n=175). Patient and surgical characteristics were assessed. Radiographic criteria were evaluated for association with incurrence of pseudarthrosis or rod fracture. <h3>RESULTS</h3> There was no significant difference in patient comorbidities. Estimated blood loss (EBL) was significantly greater in the IBF group (2.4 L vs 1.6 L, p<0.0001). Titanium interbody devices were used in 79.2% of cases and 5.5 mm cobalt chrome rods in 86.4%. There were no differences in BMP utilization. At final follow-up there was no difference in correction of SVA (PSF, IB) (20.5 mm, 32.2 mm, p=0.13), coronal alignment (5.3 mm, 6.7 mm, p=0.65), or lumbar lordosis (6.9°, 9.9°, p=0.29) compared to preoperative baseline. There was no difference in rates of rod fracture at the lumbosacral junction (13.5%, 17.7%, p=0.27), or revision surgery for L4-L5 or L5-S1 pseudarthrosis (7.3%, 10.9%, p=0.23), sagittal malalignment (3.1%, 0.5%, p=0.07), or PJK (4.2%, 6.3%, p=0.36). There was no difference in the rate of neurologic complications between the two groups (19.8%, 28%, p=0.17), or rate of revision surgery for neurologic complications (3.1%, 4.6%, p=0.47). <h3>CONCLUSIONS</h3> At long-term follow-up in a cohort of single institution patients, there were no differences in maintenance of deformity correction, or revision rates for rod fracture, pseudarthrosis, PJK, or neurologic complications when interbody fusion was utilized. The utilization of interbody technique at the lumbosacral junction is not clearly superior to posterior fusion only. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Numerical simulation of bundling of helical elastic rods in a viscous fluid

We introduce a numerical framework to study the fluid-structure interaction between two helical filaments rotating under low Reynolds number condition, motivated by the propulsion of bacteria using helical flagella. Our numerical framework couples the elasticity of the thin filaments, nonlocal hydrodynamic loading, and the contact between multiple elastic rods. Each of these three ingredients is respectively modeled by the Discrete Elastic Rods method (for a geometrically nonlinear description of soft filaments), Regularized Stokeslet Segments method (for the nonlocal drag force in a viscous fluid), and non-penetration condition between rod segments. Two helical rods rotating side by side attract each other and become closer because of their hydrodynamic interplay in a viscous environment. Depending on the initial distance between the two and their rotational frequency, the two filaments can come in physical contact. Exploiting the efficiency and robustness of the simulator, we perform a systematic parameter sweep to quantify the bundling behavior. The findings may shed light on the physics of the bio-locomotion of microorganisms and inspire the design of novel biomimetic soft robots.

Rigid reconstruction with periacetabular multiple screws after the resection of malignant pelvic tumours involving the sacroiliac joint.

Reconstruction of the pelvic ring after the resection of pelvic tumours involving the sacroiliac joint is challenging. Although pedicle screw and rod system reconstructions are commonly performed, failure at the early stage has been reported. Surgical procedures Reconstruction involving two or more strong anchor screws (iliac, ischial, and pubis screws) into the residual pelvis, connecting with at least two rods with minimal bending to the residual lumbosacral vertebra and contralateral pelvis. The above reconstruction was performed for six malignant bone and soft-tissue pelvic tumours requiring Enneking type I + IV resection. A double-barreled free non-vascularized fibular graft was used in all patients, except for one. Patients were followed up for a mean period of 51months (range, 9 to 96months), and peri-operative complications, implant failure within the follow-up period, and the clinical results of surgery were investigated. The mean age of four females and two males at the initial surgery was 37.2years. One patient developed a deep wound infection. Two patients died due to metastasis of the tumor. All patients were able to walk on their own within 12weeks of surgery. There was no implant failure, except in two patients with contralateral lumbosacral rod fracture three and fouryears after surgery, for which one patient required rod replacement. The incidence of implant failure, particularly around the resection site, was low, which may be attributed to multiple periacetabular screws and rods with minimal bending. Our rigid reconstruction method enables the rapid resumption of walking.

Innovative earthing systems for electric power substations using conductive nanoparticles

The earthing system is very important to safe human’s lives and protect power system from normal and abnormal faults. High soil resistivity regions is the main problem of installation the earthing systems in electric power substations to pass the current through the earth's surface. This paper has been overcome on high soil resistivity regions by penetrating conductive nanoparticles to have extremely low grounding resistance. Moreover, it has been succeeded to examine the methodology of the proposed Nano-Tech earthing systems in case of single rods, multiple rods and grids. Also, it has been defined optimal types and concentrations of nanoparticles for Nano-Tech grounding system to provide excellence protection for electrical substations with respect to built beneath of soil where substation is located. A comparative study has been discussed and analyzed the results of traditional and nanotechnology grounding systems.

A nets fixing device embedded in a circular floating net cage

A nets fixing device embedded in a circular floating net cage is presented in this paper, it consists of arc metal rods, wire ropes and sleeves. The arc metal rod is a circular arc metal rod with a connecting plate at both ends and a shroud ring at the inner side of the middle. Multiple arc metal rods can be fixedly connected to form a ring shape; During assembly, each arc metal rod is assembled into a circular ring. A wire rope is bound on each ring of a circular arc metal rod, and then the wire rope is pulled to sink the circular arc metal rod into the water inside the cage. Then, in the depth range of the nets, the interval and alternating sleeves of the wire ropes are inserted into the casing pipe and the circular arc metal bars, and the wire ropes are straightened and bound to the cage frame, thus forming the nets fixing device. The proposed device has simple structure, light weight, less material, high strength, and low overall price, which can effectively reduce the volume loss rate of nets, and is convenient for installation and removal.

Experimental investigation of joints with multiple glued-in rods in glued-laminated timber under axial tensile loading

This project focused on the investigation of the short-term behaviour of connections with 4, 6, 8 and 10 threaded steel rods bonded-in parallel to the grain of glulam timber and loaded in axial tension. The joints were designed with the intent to achieve the yielding failure of the rods while optimizing the cross-sections with an equal stiffness of the timber members and of the steel rods. In parallel, experimental tests and a finite element analysis (FEA) were conducted to determine the impact of the variability of the strength of the rods, the impact of the tightening of nuts and the impact of the stiffness of the load-transferring devices on the load distribution, on the behaviour of the joints.

Filamentous tangles with nemaline rods in MYH2 myopathy: a novel phenotype

The MYH2 gene encodes the skeletal muscle myosin heavy chain IIA (MyHC-IIA) isoform, which is expressed in the fast twitch type 2A fibers. Autosomal dominant or recessive pathogenic variants in MYH2 lead to congenital myopathy clinically featured by ophthalmoparesis and predominantly proximal weakness. MYH2-myopathy is pathologically characterized by loss and atrophy of type 2A fibers. Additional myopathological abnormalities have included rimmed vacuoles containing small p62 positive inclusions, 15–20 nm tubulofilaments, minicores and dystrophic changes. We report an adult patient with late-pediatric onset MYH2-myopathy caused by two heterozygous pathogenic variants: c.3331C>T, p.Gln1111* predicted to result in truncation of the proximal tail region of MyHC-IIA, and c.1546T>G, p.Phe516Val, affecting a highly conserved amino acid within the highly conserved catalytic motor head relay loop. This missense variant is predicted to result in a less compact loop domain and in turn could affect the protein affinity state. The patient’s genotype is accompanied by a novel myopathological phenotype characterized by centralized large myofilamentous tangles associated with clusters of nemaline rods, and ring fibers, in addition to the previously reported rimmed vacuoles, paucity and atrophy of type 2A fibers. Electron microscopy demonstrated wide areas of disorganized myofibrils which were oriented in various planes of direction and entrapped multiple nemaline rods, as corresponding to the large tangles with rods seen on light microscopy. Nemaline rods were rarely observed also in nuclei. We speculate that the mutated MyHC-IIA may influence myofibril disorganization. While nemaline rods have been described in myopathies caused by pathogenic variants in genes encoding several sarcomeric proteins, to our knowledge, nemaline rods have not been previously described in MYH2-myopathy.

Multiple Auer rods in a mixed-phenotype acute leukemia

Multiple Auer rods in a mixed-phenotype acute leukemia

Numerical Method for Direct Solution to Form-Finding Problem in Convex Gridshell

AbstractElastic gridshell is a class of net-like structure formed by an ensemble of elastically deforming rods coupled through joints, such that the structure can cover large areas with low self-weight and allow for a variety of aesthetic configurations. Gridshells, also known as X-shells or Cosserat Nets, are a planar grid of elastic rods in its undeformed configuration. The end points of the rods are constrained and positioned on a closed curve—the final boundary—to actuate the structure into a 3D shape. Here, we report a discrete differential geometry-based numerical framework to study the geometrically nonlinear deformation of gridshell structures, accounting for non-trivial bending-twisting coupling at the joints. The form-finding problem of obtaining the undeformed planar configuration given the target convex 3D topology is then investigated. For the forward (2D to 3D) physically based simulation, we decompose the gridshell structure into multiple one-dimensional elastic rods and simulate their deformation by the well-established discrete elastic rods (DER) algorithm. A simple penalty energy between rods and linkages is used to simulate the coupling between two rods at the joints. For the inverse problem associated with form-finding (3D to 2D), we introduce a contact-based algorithm between the elastic gridshell and a rigid 3D surface, where the rigid surface describes the target shape of the gridshell upon actuation. This technique removes the need of several forward simulations associated with conventional optimization algorithms and provides a direct solution to the inverse problem. Several examples—hemispherical cap, paraboloid, and hemi-ellipsoid—are used to show the effectiveness of the inverse design process.

Research of multiple metal rods joining node in spatial construction, using one welding connection

Elements in the nodes of spatial bar structures can be assembled either with bolted connections or with welding. For welded nodal connections, each element should be attached separately. This complicates the process of manufacturing the structure and increases the labour input while assembling this structure. The so-called “tub welding node” does not have such flaws as several bars are joined by a single weld formed during a single pass of the welding machine. The weld of such a node is in a complex stress and strain state. It means that a relatively small weld should constantly take heavy loads. To assess the stress and strain state of the welding node, the researchers conducted numerical studies in the SolidWorks software system. The calculation model of the structural node was based on the results of a particular existing structure examination. These empirical numerical studies revealed that stresses are evenly distributed in the body of the weld, but its surface stresses exceed the stresses inside the weld. There are some areas on the weld surface that exceed the yield strength of steel. Still, the size of these areas is negligible.

Comprehensive Evaluation of Accessory Rod Position, Rod Material and Diameter, Use of Cross-connectors, and Anterior Column Support in a Pedicle Subtraction Osteotomy Model: Part I: Effects on Apical Rod Strain: An In Vitro and In Silico Biomechanical Study.

In silico finite element study. The aim of this study was to evaluate the effect of six construct factors on apical rod strain in an in silico pedicle subtraction osteotomy (PSO) model: traditional inline and alternative Ames-Deviren-Gupta (ADG) multi-rod techniques, number of accessory rods (three- vs. four-rod), rod material (cobalt-chrome [CoCr] or stainless steel [SS] vs. titanium [Ti]), rod diameter (5.5 vs. 6.35 mm), and use of cross-connectors (CC), or anterior column support (ACS). Rod fracture following lumbar PSO is frequently reported. Clinicians may modulate reconstructs with multiple rods, rod position, rod material and diameter, and with CC or ACS to reduce mechanical demand or rod contouring. A comprehensive evaluation of these features on rod strain is lacking. A finite element model (T12-S1) with intervertebral discs and ligaments was created and validated with cadaveric motion data. Apical rod strain of primary and accessory rods was collected for 96 constructs across all six construct factors, and normalized to the Ti two-rod control. Regardless of construct features, CoCr and SS material reduced strain across all rods by 49.1% and 38.1%, respectively; increasing rod diameter from 5.5 mm to 6.35 mm rods reduced strain by 32.0%. Use of CC or lumbosacral ACS minimally affected apical rod strain (<2% difference from constructs without CC or ACS). Compared to the ADG technique, traditional inline reconstruction reduced primary rod strain by 32.2%; however, ADG primary rod required 14.2° less rod contouring. The inline technique produced asymmetrical loading between left and right rods, only when three rods were used. The number of rods and position of accessory rods affected strain distribution on posterior fixation. Increasing rod diameter and using CoCr rods was most effective in reducing rod strain. Neither CC nor lumbosacral ACS affected apical rod strain. N/A.

Comprehensive In Silico Evaluation of Accessory Rod Position, Rod Material and Diameter, Use of Cross-connectors, and Anterior Column Support in a Pedicle Subtraction Osteotomy Model: Part II: Effects on Lumbosacral Rod and Screw Strain.

In silico finite element study. The aim of this study was to evaluate effects of six construct factors on rod and screw strain at the lumbosacral junction in an in silico pedicle subtraction osteotomy (PSO) model: traditional inline and alternative Ames-Deviren-Gupta (ADG) multi-rod techniques, number of accessory rods (three-rod vs. four-rod), rod material (cobalt-chrome [CoCr] or stainless steel [SS] vs. titanium [Ti]), rod diameter (5.5 vs. 6.35 mm), and use of cross-connectors (CC), or anterior column support (ACS). Implant failure and pseudoarthrosis at the lumbosacral junction following PSO are frequently reported. Clinicians may modulate reconstructs with multiple rods, rod position, rod material, and diameter, and with CC or ACS to reduce mechanical demand. An evaluation of these features' effects on rod and screw strains is lacking. A finite element model (T12-S1) with intervertebral discs and ligaments was created and validated with cadaveric motion data. Lumbosacral rod and screw strain data were collected for 96 constructs across all six construct factors and normalized to the Ti 2-Rod control. The inline technique resulted in 12.5% to 51.3% more rod strain and decreased screw strain (88.3% to 95%) compared to ADG at the lumbosacral junction. An asymmetrical strain distribution was observed in the three-rod inline technique in comparison to four-rod, which was more evenly distributed. Regardless of construct features, rod strain was significantly decreased by rod material (CoCr > SS > Ti), and increasing rod diameter from 5.5 mm to 6.35 mm reduced strain by 9.9% to 22.1%. ACS resulted in significant reduction of rod (37.8%-59.8%) and screw strains (23.2%-65.8%). Increasing rod diameter, using CoCr rods, and ACS were the most effective methods in reducing rod strain at the lumbosacral junction. The inline technique decreased screw strain and increased rod strain compared to ADG. N/A.

Load-carrying capacity of timber joints with multiple glued-in steel rods loaded parallel to grain

The joints with glued-in steel rods are efficient joints in the design of timber structures, due to their high stiffness, strength and fire resistance. The ductile behaviour of joints can be achieved through designing the yielding of steel rods prior to wood failure. In practice, the joints are generally with multiple rods rather than single rod. In the case of multiple glued-in rods, the yielding of single rod is designed as prior failure by using mild steel rod, and the load-carrying capacity of joints is expected to be equal to the yield capacity of single rod multiplied by the number of rods. However, the actual pull-out capacity of single rod in timber joints with multiple glued-in rods can be less than that in timber joints with a single glued-in rod, due to the group effect of glued-in rods. Thus, the brittle failure of pull-out of rods can still occur prior to the yielding of steel rods in timber joints with multiple glued-in rods, though the yielding of single rod is designed as prior failure. The pull-out capacity of multiple rods can generally be considered as the pull-out capacity of single rod multiplied by the effective number of rods instead of the actual number of rods. Therefore, it is necessary to determine the effective number of rods in the case of pull-out of rod.This paper presented an experimental investigation on joints composed of multiple glued-in steel rods (two and four rods with different rod spacing) in glued-laminated timber with the pull-out failure mode. The actual experimental results combined with those from literatures, were used to analyze the influence of main factors, e.g. rod diameter, slenderness ratio of rods, number of rods and rod spacing to diameter, on the effective number of rods. Afterwards, based on these main factors, an empirical expression of the effective number of rods was derived. Finally, a model of load-carrying capacity for timber joints with multiple glued-in rods was proposed. The load-carrying capacity of timber joints with multiple rods should be calculated as the minimal value between yielding capacity of a single rod multiplied by the number of rods and pull-out capacity of a single rod multiplied by the effective number of rods. The proposed model is capable of predicting the failure mode and load-carrying capacity for multiple rods.

Optimal and effective technique for particle packing

In various fields ranging from manufacturing or pharmaceutical industry to agriculture or automotive industry air filters and -dryers filled with porous desiccant media are used for industrial air preparation. It is necessary to increase the mass of particulate material filled into the dryer for improving its efficiency. Practically this means decreasing porosity of the filler media. In order to achieve this, mechanical excitation (ensured by a vibration platform) is commonly used. However, applying outer excitation decreases the efficiency of filling procedure because of the high energy consumption of the vibratory device. To avoid unnecessary energy consumption it is recommended to examine the possibility of filling more particles into the canister without outer excitation. According to this in our present paper the gravitational deposition of particulate materials was investigated from viewpoint of porosity. Main idea of this research was the usage of the so called “snowstorm” filling technique. A conical hopper and under this multiple cylindrical rods were used to reach uniform deposition and high value of particle packing density. Thus efficiency of air preparation units may be increased as it is possible to fill more material into the container without additional energy usage compared to normal gravitational deposition.

An investigation into the fatigue damage of a long flexible cylinder with multiple control rods in crossflow

In the field of offshore engineering, the control rod is a common passive device to suppress the vortex-induced vibration (VIV) of cylindrical structures. Some key parameters of control rods (diameter ratio, spacing distance, coverage rate and attack angle) have a great influence on the VIV fatigue life of the cylinder. This paper aims to investigate the fatigue damage of the main flexible cylinder with multiple control rods caused by VIV based on rainflow counting and a standard S–N curve, with the final purpose of studying the effectiveness of multiple control rods, in different configurations around the cylinder in improving the structural fatigue life. The results show that control rods can suppress the VIV response of the cylindrical structure and reduce its fatigue damage effectively. The reduction effect of the control rods is very sensitive to the spatial arrangement. The reduction effect of the 3 control rods is the best at the attack angle of 40°, while that of the 4 control rods is the best at the attack angle of 30°. The fatigue damage of the flexible cylinder can be reduced to a lower level with 4 control rods. In addition, “mode transition”, a specific feature of VIV in uniform flow, is found in the experiment and has a strong influence on fatigue life.

High-performance boron-doped silicon micron-rod anode fabricated using a mass-producible lithography method for a lithium ion battery

Although silicon (Si) attracts great attention as a high-capacity anode material in lithium ion batteries (LiBs), a large volume being expanded during charge/discharge (de/lithiation) cycling is a significant problem resulting in a fast capacity fade. To prevent the problem, a variety of Si structures with nano/microscales have been incorporated into the anode, but such structures still have difficulties in terms of mass production. Herein, we present a new way to repetitively produce micron boron (B)-doped Si rods from Si wafer through laser interference lithography (LIL) in combination with the metal assisted chemical etching (MACE) process, enabling the mass-production of multiple Si rods at low cost. Moreover, the effects of the B-doping level of the produced Si rods on the electrochemical LiB performances are studied in detail. As a result, the lightly B-doped Si rod (~1015 atoms cm−3) anodes exhibit the highest initial capacity of 3524 mAh g−1 and cyclic performance, showing a high average Coulombic efficiency (CE) of 98.1% and a capacity fading rate (per cycle) of 0.11% during 500 cycles. It is due to the highest kinetics of de/lithiation on the surface of the lightly B-doped Si rod attributed to favorable phase transition of Si and diffusion of Li ions.

Advances in Spinal Fusion Strategies in Adult Deformity Surgery.

As the frequency of adult deformity surgery (ADS) continues to increase, our understanding of techniques that enhance fusion must continue to evolve because pseudarthrosis can be a serious and costly event. We sought to conduct a review of the literature investigating techniques that can enhance outcomes of ADS. Two databases were searched for keywords such as "advances in spinal fusion," "new technology in adult spinal deformity," "interbody devices for adult spinal deformity," "adult spinal deformity rods," and "screw design in adult spinal deformity" to examine recent literature and trends in ADS. We identified 45 articles for our review. Topics studied include the use of multiple rods, interbody fusion, distal fixation techniques, and bone morphogenetic protein or iliac crest bone graft. Many recent innovations in treatments to enhance fusion in ADS have been studied, some more controversial than others. Further research into the efficacy of these techniques may increase fusion rates in ADS.