Rod Diameter Research Articles

The effect of C2 screw type on perioperative outcomes and long-term stability after C2-T2 posterior cervical decompression and fusion.

To determine if C2 pedicle versus pars screw type predicts change in fusion status, C2 screw loosening, cervical alignment, and patient-reported outcomes measures (PROMs) after C2-T2 posterior cervical decompression and fusion (PDCF). All adult patients who underwent C2-T2 PCDF for myelopathy or myeloradiculopathy between 2013-2020 were retrospectively identified. Patients were dichotomized by C2 screw type into bilateral C2 pedicle and bilateral C2 pars screw groups. Preoperative and short- and long-term postoperative radiographic outcomes and PROMs were collected. Univariate and multivariate analysis compared patient factors, fusion status, radiographic measures, and PROMs across groups. A total of 159 patients met the inclusion/exclusion criteria (76 bilateral pedicle screws, 83 bilateral pars screws). Patients in the C2 pars relative to C2 pedicle screw group were on average more likely to have bone morphogenic protein (p = 0.001) and four-millimeter diameter rods utilized intraoperatively (p = 0.033). There were no significant differences in total construct and C2-3 fusion rate, C2 screw loosening, or complication and revision rates between C2 screw groups in univariate and regression analysis. Changes in C2 tilt, C2-3 segmental lordosis, C0-2 Cobb angle, proximal junctional kyphosis, atlanto-dens interval, C1 lamina-occiput distance, C2 sagittal vertical axis, C2-7 lordosis, and PROMs at all follow-up intervals did not vary significantly by C2 screw type. There were no significant differences in fusion status, hardware complications, and radiographic and clinical outcomes based on C2 screw type following C2-T2 PCDF. Accordingly, intraoperative usage criteria can be flexible based on patient vertebral artery positioning and surgeon comfort level.

Formation and growth of wipe blockages due to a vertical obstruction in sewers: Experimental analysis to policy and management strategies

Improper disposal of wipes results in significant sewer blockages, especially during the COVID-19 pandemic. However, the formation and growth of wipe blockages and their backwater effect in sewers have not been studied. This study employed a vertical rod to simulate sewer obstructions such as tree root intrusion in sewers. Stochastic interactions among wipes, turbulent flow, and the obstruction were experimentally studied in a circular pipe (diameter D = 25 cm), with systematic variations in flow Froude number (Fr), wipe length (L), flow depth (H), submerged rod length (hrod), and rod diameter (drod). It was found that the mean area ratio of wipes (ratio of projected area in water to original surface area of the wipe) ranged from 0.14 to 0.30, indicating the distorted shapes in water. The entrapment probability P (ratio of entrapped to released wipes) for a single wipe was closely correlated with Fr, H/D, L/H, drod/H, and hrod/H, with a maximum value of 0.90. With the increase in the number of wipes released, the influence of the obstruction on wipe accumulation processes became negligible. New equations were developed for characterizing entrapment probability, blockage length, and backwater rise, which can be used to predict the development of wipe blockages and sewage levels. Based on the research findings, policy and management strategies were proposed for wipe blockage reduction in sewers.

475 Molybdenum-Rhenium Rods in Complex Adult Spine Surgery Without Rod Fractures: A Multicenter Retrospective Case Series

INTRODUCTION: In complex spine surgery, current pedicle screw systems with 5.5 mm titanium, cobalt chromium or stainless steel rods have rod failure rates of approximately 9% with a minimum of 1-year follow-up. The fracture rate with these alloys increases to approximately 22% in PSO cases.1 Molybdenum-rhenium has demonstrated superior yield strength and fatigue endurance limit compared to Ti-6Al-4V and CoCr. METHODS: Retrospective, multicenter, case series. Inclusion criteria were = 4 levels posterior instrumented fusion with 4.5 mm molybdenum-rhenium rods, age = 18 yrs and 6 months or longer radiographic and followup. RESULTS: One hundred and fifty-nine (159) consecutive patients from ten different medical centers that had spinal surgery from August 2019 until April 2022 met inclusion criteria. Mean age was 63 ± 11.8 years; 50% women; 31% smokers; 19% diabetic and the mean BMI was 30 ± 7.3. The mean number of levels fused was 5.9 ± 2.7; 22.6% 4 levels, 64.2% 5-9 levels and 13.2% 10 levels or greater. Approximately half were thoracolumbar (27.7%) or thoracolumbar to pelvis (24.5%) and approximately half were lumbar-sacral (47.2%). Thirty-eight patients (24%) had a PSO and 59 patients (39%) had a SPO. All cases were done with molybdenum-rhenium 4.5 mm diameter rods. There were no RFs reported in the 159 cases (0/159; 0.0%) at 22.36 months mean follow-up. CONCLUSIONS: There was no incidence of RF in the 159 consecutive patients who underwent complex spine surgery involving multiple levels and osteotomies. A pedicle screw system based upon molybdenum-rhenium 4.5 mm rods provides superior fracture resistance particularly in complex spine procedures. 1 Smith JS, et al., Prospective multicenter assessment of risk factors for rod fracture following surgery for adult spinal deformity. J Neurosurg Spine. 2014 Dec; 21(6): 994-1003.

피복아크 용접봉의 직경에 따른 용접봉 소요량, 용접시간, 용접 경제성에 관한 비교 연구

This study compared the characteristics of welding rod consumption, welding time, and welding economy of welding rods of various diameters commonly used in shielded metal arc welding to select an appropriate welding method for structures. The results of the study revealed that for welding a test piece, an average of 3.5 rods was consumed for ø3.2-mm welding rods, while an average of 1.93 rods was consumed for ø4-mm welding rods. Converting the consumption to the cost of welding revealed approximately 601 KRW for ø3.2-mm welding rods and approximately 560.3 KRW for ø4-mm welding rods. Using larger ø4-mm welding rods reduced the cost by 40.7 KRW, which is equivalent to a 7.3% savings in rod welding expenses.

Measurement of Postoperative Apical Vertebral Rotation Using Radiographic Images in Adolescent Idiopathic Scoliosis-Quantitative Evaluation Using Inverse Trigonometric Functions.

Conventional methods for analyzing vertebral rotation are limited to postoperative patients who underwent posterior fusion. A previous methodology calculated vertebral rotation using inverse trigonometric functions based on the length of the pedicle screw (PS). Accordingly, this study evaluates rotational deformity in patients with postoperative adolescent idiopathic scoliosis (AIS) using inverse trigonometric functions. This retrospective single-center study includes patients with AIS who underwent posterior fusion surgery. Postoperative radiography and computed tomography (CT) scans were retrospectively evaluated. The magnification ratio was calculated using the rod diameter (δ=lateral/frontal rod diameter), and the visible screw lengths were measured using radiographs. The rotation angle was calculated using the apex of the main curve and the lower instrumented vertebra (LIV) (rotation angle=tan-1 (lateral PS length/(δ×frontal PS length))) immediately following the surgery as well as two and five years postoperatively. The correlation between the direct CT measurement and postoperative rotation angle progression was investigated. The crankshaft phenomenon (CSP) and distal adding-on (DAO) were evaluated as postoperative deformities. CSP was defined as a 5° increase in rotation angle. Seventy-eight patients (age: 15.3±2.0 years, eight boys and seventy girls) were included. The rotation angle was strongly correlated with CT rotation measurements (r=0.87). The mean rotation angle at the apex and LIV did not change within five years postoperatively (mean: 0.5±3.6° and 0.4±3.4°, respectively). CSP and DAO were observed in 6.4% and 3.8% of patients, respectively. The inverse trigonometric method is useful to quantitatively evaluate the postoperative rotation angle and identify CSP.

Utilizing numerical simulation to determine the reasonable parameters for the design of hydraulic rock-splitting head

The hydraulic rock splitter with a wedge-type splitting head has various advantages, such as simple operation, high work efficiency, safety, shortened work time, and minimal environmental impact. The splitting head driven by a hydraulic cylinder, is the focus of this research, as it directly influences work efficiency. This paper introduces the general structure of the rock splitter machine and the hydraulic cylinder-driven splitting head, along with the method for selecting suitable parameters. To evaluate and select suitable variables, this study establishes procedures and calculation methods for two sets of problems: determining the parameters for the wedge and the parameters for the hydraulic cylinder. The numerical test results provide a design dataset applicable to real-world scenarios, including the wedge angle, cylinder stroke, cylinder diameter, pressure, minimum cylinder wall thickness, and piston rod diameter, corresponding to the respective rock-splitting forces. These parameters meet the set objectives of cylinder pushing force and minimize the cross-sectional area of the cylinder body, contributing to weight reduction and operational convenience.

A rotary lead viscoelastic damper with force-resisting capacity: Experimental verification and parametric analysis

The seismic safety of buildings can be improved by installing energy dissipators. A rotary lead viscoelastic damper (RLVD) with force-resisting capacity is proposed in this paper. RLVD consists of laminated rubber, lead rods, a cylindrical pin, and steel plates. The RLVD will rotate around the cylindrical pin when an earthquake shakes the building, resulting in the shaking energy mainly being dissipated by the plastic deformation of lead rods. To justify the reasonability and feasibility of RLVD, a prototype of RLVD was manufactured and tested under cyclic loading. The test results showed that the working mechanism of RLVD is reasonable and effective. The hysteretic curves of RLVD were plump and characterized by a bilinear behavior. A numerical model of RLVD in Abaqus was established and calibrated by the test results. A parametric analysis was conducted to further investigate the effect of the key design parameters of RLVD on its mechanical behavior. The parameter analysis showed that the number and diameter of lead rods have little effect on the mechanical properties of RLVD under the constraint of the same total cross-section area of lead rods. The yielding moment and energy dissipation of RLVD were affected by the distance from the center of the lead rod to the center of the cylindrical pin while the post-yielding stiffness of RLVD was affected by the thickness and shear modulus of the laminated rubber. The concept of the RLVD is justified.

Growth of β-Ga2O3 crystal with a diameter of 30 mm by laser-diode-heated floating zone (LDFZ) method

To investigate the effect of high-power laser heating on the floating zone (FZ) method, a crystal of β-Ga2O3 was grown by the LDFZ method using a newly developed optical system equipped with a 20-kW laser diode (LD) system as a heat source. The growth started from a twin-free seed crystal with a diameter of 7 mm and the diameter of the crystal was increased gradually up to 30 mm. With increasing the diameter of the crystal, three patterns of the beam intensity profile were switched to heat the whole of the molten zone locally and intensively. The intensity profile of the five beamlets irradiating the sample was adjusted with a combination of the zooming by the optical system and the partial blocking by the alumina cylinder. By the proper tuning of the beam profile and the proper selection of the diameter of the feed rod, the molten zone was kept stable against gravity. The obtained crystal has a layer texture without clear facets or cracks. It almost conserves the crystallographic direction of the seed crystal but is twinned except for a twin-free region near the seed crystal.

Natural Vibration Analysis of a Simple Vibration Absorber

The slender rod + mass block system is a typical elastic vibration absorber structure, with a simple structural form and strong design ability. It has wide application in engineering. This paper focuses on the inherent vibration characteristics of elastic structures and discusses the effects of gravity and typical geometric parameters on the modal frequency of the absorber structure. The calculation results show that, under the action of gravity, the overall strain rate is very low, and the impact of gravity on the structure's vibration characteristics can be ignored. With the increase of the length of mass block, length of slender rod, and the diameter of the mass block or with the decrease of diameter of slender rod, modal frequency of the elastic structure gradually decreases. The research conclusions can provide reference for the optimization design of simple elastic structures in engineering projects.

Experimental study on the influence of abrasive flow machining on the surface quality and mechanical properties of BCC lattice structure manufactured by L-PBF

During the L-PBF process for preparing porous biomaterials, the "spheroidization effect" and the "stair-step effect" lead to defects such as pore clogging and rod diameter thickening in the actual components. These defects affect the part's dimensional accuracy, which in turn has the critical influence on the mechanical properties of the workpiece. Thus, suitable post treatment methods are required to improve the surface quality of porous biomaterials. This paper aims to investigate the effects of abrasive flow machining on the surface quality and mechanical properties of body-centered cubic (BCC) lattice-structured specimens molded by L-PBF at different pressures and abrasive concentrations and their mechanisms. Experimental results indicate that the number of powders adhering to the rod diameter of the member is significantly reduced after the abrasive grain flow process treatment. The roughness of the rod diameter surface is reduced from 17.48 μm to 6.82 μm, and the surface finishing is improved by 60.98%. The abrasive flow machining can effectively eliminate the "spheroidization effect" on the mechanical properties of the lattice structure. The maximum compressive strength of specimens subjected to abrasive flow machining have all been increased. Especially, with the abrasive flow machining under the pressure of 4 MPa and the abrasive grain concentration of 60%, the maximum compressive strength of the specimens was even been increased by 8.89%.

Miniaturized acoustic concentrators for ultrafast 3D ultrasound imaging

Ultrafast 3D ultrasound imaging is a rapidly growing research field that enables real-time imaging at a high frame rate and in a non-invasive manner. Currently, to achieve ultrafast 3D ultrasound, plane or diverging waves from virtual sources are used. These virtual sources can be considered as focal points during emission, allowing for improved transmission of ultrasonic energy. However, they have limitations in terms of transmitted energy, complex electronics, and timing issues, which impact the quality of the resulting images. To address this, a study was conducted to design and experiment with new miniaturized ultrasound transmitters based on cylindrical waveguides with tapered sections. These transmitters, with a diameter of approximately 100 μm, can replace the virtual sources. A numerical study based on 2D axisymmetric Finite Element Modeling (FEM) is first performed to model the transmission and reflection of longitudinal ultrasonic waves through various cylindrical rods. The results demonstrated that the transmission depends on the diameter ratio, frequency and longitudinal mode order (L0, L1, L2, etc.). An experimental study is then conducted on a stainless steel waveguide instrumented with 6mm piezo discs. The mechanical energy, estimated using Laser Doppler Vibrometer is transmitted through a 150 μm diameter rod, allowing mechananical focusing in the frequency range between 0.5 and 5 MHz. The application of this method to separate emission/reception transducers is then demonstrated for 3D ultrafast imaging.

Numerical and experimental study of directional annealing to prepare columnar grains of TiAl alloy

Directional annealing (DA) is a novel technique to prepare colunmar grains or single crystal in TiAl alloys without melt contamination. Both numerical simulation and experiments were conducted to investigate the directional annealing (DA) of a Ti48Al alloy in this paper. The temperature distribution of the TiAl rod under different DA parameters were calculated and discussed by Finite Element (FE) method. The results showed that the temperature field was significantly influenced by hot zone temperature, moving rate of induction coil, rod diameter and cooling condition. Once induction heating started, the temperature of Ti48Al rod rose rapidly and reached a steady state after about 400 s. The effective heat area (single phase zone) enlarged with the increase of preset temperature. With the decreasing movement rate of induction coil, the α/α+γ interface became more planar, and this rule also applied to the effect of the rod diameter on α/α+γ interface. Under the guidance of calculation results, optimized parameters were proposed to directionally annealing Ti48Al alloy. Rods with a diameter of 8 mm were induction-heated under the hot zone temperatures of 1673 K and 1693 K correspondingly. In the range of α single phase, the transformation of γ→α phase occurred completely and α grains directionally coarsened with the movement of hot zone. In this way, columnar grains in Ti48Al alloy were successfully formed in a solid state.

Effects of structure parameters on performances of laser powder bed fusion processed AlSi10Mg body-centered cubic lattices

The study aims to explore the impact of structural parameters on the formability, mechanical properties, and heat conductivity of body centered cubic (BCC) lattice structures produced through laser powder bed fusion (LPBF). The BCC lattice structures with varied cell diameters and cell sizes were fabricated using LPBF. Surface morphologies, compression properties, and numerical simulation of heat transfer were carried out. Results indicated that the relative density of the BCC structure was influenced by the diameter and size of the cell. An increase in the diameter or a decrease in the size of the cell led to an increase in the relative density of the BCC lattice structure. However, the surface forming quality decreased. On the other hand, the compressive strength of the structure increased, and the heat transfer property was also enhanced. The BCC lattice structure achieved its highest relative density and obtained a peak compressive strength of 320.66 MPa when the cell rod diameter was 1.5 mm and the cell size was 3 mm.

1D α-NiMoO4 nanorods/reduced graphene oxide nanocomposite based efficient electrocatalyst for oxygen evolution reaction and p-nitrophenol sensing

In this work, nickel molybdate/reduced graphene oxide (α-NiMoO4/rGO) based bifunctional electrocatalysts for oxygen evolution reaction (OER) and p-nitrophenol (p-NP) sensing were studied. To replace noble metal-based catalysts for oxygen evolution reactions, it is essential to develop a potential alternative low-cost, electrochemically active catalyst. Even at a very low level p-NP present in water is harmful to the environment, so a rapid and sensitive method for detecting the presence of p-NP is indispensable. In this study, α-NiMoO4/rGO nanocomposite has been synthesized by hydrothermal method and used for OER and p-NP sensing. The XRD and Raman analysis confirm the α phase of NiMoO4 and SEM, and HRTEM studies confirm that 1D NiMoO4 growing on 2D rGO and the length and diameter of NiMoO4 rod are 5–10 μm and 50 nm, respectively. The α-NiMoO4 and α-NiMoO4/rGO showed an over-potential of 510 mV and 450 mV vs RHE, respectively for OER. The Tafel slope of the α-NiMoO4 and α-NiMoO4/rGO exhibited 159 mV dec−1 and 121 mV dec−1, respectively. The composite was found to split water into oxygen continuously for 23 h indicating its good stability for OER. For the electrochemical sensing of p-NP, the best OER performed α-NiMoO4/rGO-10 composite was chosen and modified with GCE. The sensor exhibits two sets of the linear range 0.5–10 μM and 30–500 μM for sensing of p-NP with a limit of detection 0.256 μM and sensitivity of 3.5042 μA cm2/μM. Cyclic voltammetry of α-NiMoO4/rGO/GCE differentiate different nitrophenol isomers.

Experimental and machine learning study on a novel high-performance hybrid steel-grout connector for cross-laminated timber panels under pre-yield cyclic loads

This work presents the results from quasi-static cyclic tests on a novel hybrid steel-grout connector for cross-laminated timber (CLT) panels. These test series are part of an experimental, analytical, and numerical research program to develop reliable and resilient connections for hybrid CLT mass timber structural assemblies. Each designated connector arrangement’s cyclic loading step path has been anchored to the yield point; this latter was obtained as the average of the seven replicates of monotonic tests. From the cyclic test results, mechanical characteristics, namely, the secant stiffness and the residual slip, have been evaluated and discussed. Furthermore, machine learning (ML) models based on deep neural networks have been developed to predict the mechanical characteristics of connectors in the function of the mechanical and geometrical properties of each material used. The developed ML models proved to be able to predict the connector’s stiffness and residual slip and were used to infer the effects of experimental variables on these performance parameters. It was shown that the steel rod and grout diameters are the most influencing parameters regarding the secant stiffness of connectors. As for the residual slip, it was found that the grout diameter and the steel rod strength class are the most influencing parameters. Furthermore, it was observed that a grout-to-rod diameter ratio of about 3.6 enables maximization of the secant stiffness while minimizing the residual slip. Lastly, polynomial equations were developed and found to be able to predict the secant stiffness and residual slip of connectors with a coefficient of determination of 0.99 and 0.98, respectively.

X-ray Fluorescence Analysis of the Elemental Composition of Tungsten, Nickel and Copper

The purpose of this work was to conduct an X-ray fluorescence analysis of the elemental composition of tungsten, nickel and copper metal waste using an Olympus Delta portable spectrometer.Methods. To determine the chemical composition of raw materials, samples of metal waste in the form of copper rods, tungsten rods of various diameters and scraps of nickel plates intended for recycling were examined. To determine the elemental composition of metal waste, the method of X-ray fluorescence analysis (XFA) was chosen. The X-ray fluorescence method is based on the ratio of the intensity of X-ray fluorescence to the concentration of elements in the sample. Samples irradiated with powerful X-ray tube radiation, in response, emit characteristic fluorescent radiation of atoms proportional to their concentration in the sample. This method allows us to qualitatively assess the elemental composition of complex samples without violating their physico-chemical properties with minimal time costs. The Olympus Delta spectrometer was used as an express analyzer of metals and alloys, with the help of which experimental data on the composition of metal waste of tungsten, nickel and copper were obtained.Results. Based on the conducted studies aimed at X-ray fluorescence analysis of the elemental composition of tungsten, nickel and copper metal waste using the Olympus Delta portable spectrometer, it was found that the samples of the studied metal waste correspond to the following grades of alloys: tungsten rod made of tungsten grade VA; nickel plate made of nickel grade PNK-0T1; copper rod made of copper grade M3r.Conclusion. The results obtained will allow further research on their processing by the method of electroerosive dispersion and reuse in the production of heavy tungsten alloys. Renovation of metal waste, including tungsten, nickel and copper metal waste, will contribute to resource conservation, import substitution and ensuring the technological sovereignty of the Russian Federation.

Improving Bond Performance of Near-Surface Mounted Steel Ribbed and Threated Rods in the Concrete

In this study, the experimental findings of twenty pull-out tests on the bond efficiency of threaded/ribbed steel rods used in near-surface mounting (NSM) are presented. On a groove (20 × 20 mm) that was slotted in one of the sides of a concrete block measuring 250 × 250 × 200 mm, a pull-out experiment was performed. The primary factors are the slot-filling materials (substrate concrete and epoxy paste), bonded length (equal to 5, 7, 10, and 15 times the rod diameter), surface pattern conditions (conventional ribbed reinforcing rebar and threaded bolt), use of nuts or rings welded at the free end of the bonded length, and use of straight or spiral wire welded along the length of the bonded length. The tested specimens' ultimate bond strength, slip, bond stress–slip response, failure patterns, stiffness, and ductility are recorded and assessed. The results showed that the ultimate bond strength and corresponding slip of ribbed rods cemented with epoxy were higher by 11.11% and 199%, respectively, than those of ribbed rods submerged in the substrate. Over the controls, all NSM epoxy-rods exhibited a greater ductility. As the bonded length increased, the ultimate bond strength of NSM rods fell by 12–32%. As the bonded length increased, the stiffness decreased. On the other hand, the ductility of NSM epoxy-rods increased as the bonded length increased. All applied schemes such as nuts, rings, longitudinal bars, and spiral bars significantly improved the ultimate bond strength (maximum = 25.93%) and corresponding slip (maximum = 166.67%) of NSM threaded rods as compared to the control ones.

Modelling analysis and optimisation of porous structural scaffolds for human bones

Two different types of unit structure models, ortho tetrahedral and hexahedral, are established, and a series of different porosities are obtained by controlling the parameters such as rod diameter and rod length, and the porous structure can be obtained by stacking the unit structure in an orderly manner in the three-dimensional space, and then finite element simulation and analysis are carried out by simulating compression experiments using Ansys to obtain the equivalent stresses, deformation maps and data, and the elastic modulus, which is close to that of the human hip bone, is calculated to investigate the mechanical properties under different porous structures and different porosities. The modulus of elasticity was calculated to be close to that of the human hip bone, and the mechanical properties were investigated under different porous structures and different porosities. The Fluent module is also used to simulate the fluid field, and the pressure and velocity maps of the fluid inside the two porous structures are obtained for comparative and comprehensive analyses. From the simulation of the created porous model, it is learnt that, for the same structure, with the increase of porosity, the equivalent force and deformation increase and the elastic modulus decreases significantly; for the same porosity, under the same loading environment, the longitudinal deformation of the hexahedron is smaller than that of the tetrahedron, its equivalent force is much lower than that of the tetrahedron, and it has suitable elastic modulus. Its strength is higher than that of the tetrahedron when under pressure. When the fluid flows in the hexahedron, the hexahedral structure is less compressed than the ortho tetrahedral structure, and the flow rate is more suitable for the blood flow rate in the human body.

Demonstration of a high-performance continuous casting process for cobalt alloy ASTM F75

A modified horizontal high performance continuous casting configuration was investigated by the introduction of a mechanically durable and thermally insulating zirconia-based break-ring and the application of a copper-beryllium die for the casting of cobalt alloy ASTM F75 (Co: balance, Cr: 27 wt%, Mo: 5 wt%). Successful casting was demonstrated with an 8 mm diameter rod with good physical properties and a metallic phase structure and distribution consistent with the standard.

Numerical Analysis for Effects of Grid Spacer Vane on Flow-Thermal Characteristics of Two Phase Flow in a 5×5 Rod Bundle

Numerical Analysis for Effects of Grid Spacer Vane on Flow-Thermal Characteristics of Two Phase Flow in a 5×5 Rod Bundle