Tip Of Rod Research Articles

Arthroscopic approach to the spring (calcaneonavicular) ligament

BackgroundThis research studied the safety and efficacy of a new portal to the spring ligament. This portal is located just plantar to the insertion of the posterior tibial tendon and above the fibrous septum between the posterior tibial and the flexor digitorum longus tendons. MethodsTwelve fresh frozen foot and ankle specimens were used. The distance between the accessory medial portal and the medial plantar nerve was measured. The relation between the medial plantar nerve and the spring ligament was studied. The depth that can be reached through the portal was also assessed. ResultsThe average distance between the insertion point of the 3mm diameter metal rod and the medial plantar nerve was 20(6–27)mm. The medial plantar nerve located at lateral third of the ligament in 8 specimens (67%), middle third in 2 specimens (17%) and medial third in 2 specimens (17%). The tip of rod can reach Zone A in all specimens. ConclusionThis study demonstrated that arthroscopic approach and repair of the spring ligament can injure the medial plantar nerve. Clinical relevanceThe clinical relevance of this cadaver study is that it confirmed the feasibility of arthroscopic approach to the whole span of the spring ligament and alerted the potential risk of injury to the medial plantar nerve during arthroscopic assisted repair of the ligament.

Boosting and Localizing Near-Field in Plasmonic Mirror-Image Nanoepsilon

A novel plasmonic mirror-image nanoepsilon (MINE) structure is studied to achieve significantly enhanced and localized near-field. It is well-known that the nanorod dimer is able to gain a high local field at the center of the structure by adjusting its rod width, rod length, and gap distance. When adopting an auxiliary nanoring structure electron reservoirs surrounding the nanorod-dimer to form the MINE structure, the local field can be further enhanced owing to a large amount of charges into sharp dimer structure which can confine the accumulation of charges to apexes. Thus, better synergistic interaction of gap effect and lightning-rod effect can be achieved for high field enhancement around nanoscale gap. The symmetric mode in the MINE structure enables strong near-field with a concentrated distribution around the gap. The influences of rod-tip angle and gap distance on the optical properties of plasmonic MINE structures are numerically investigated. With reducing the rod-tip angle and gap distance, considerable enhancements on the field intensities at the rod tips and the gap center can be attributed to the improved lightning-rod and gap effects. The near-field intensities at the rod tip and gap center are dramatically enlarged ~1.94 × 104 and ~1.41 × 104 times with the rod-tip angle of 41° and gap distance of 10 nm, and the near-field is localized within an extremely small range. These features are very beneficial for various plasmonic applications.

Development of a Low-Temperature Irradiation Capsule for Research Reactor Materials at HANARO

A new capsule design was prepared and tested at the High Flux Advanced Neutron Application Reactor (HANARO) for neutron irradiation of the core materials of research reactors at a low temperature (of <100°C). The capsule was first designed at HANARO to have the coolant flow through the capsule to cool down the irradiation temperature of the specimens. The safety of the newly designed capsule should be fully checked before irradiation testing. Out-pile performance and endurance testing before HANARO irradiation testing was performed using a capsule in the HANARO out-pile test facilities. The new capsule had a much higher coolant flow-induced vibration than a standard capsule, resulting in fatigue failure at the rod tip of the capsule. The lifetime of the rod tip was greatly improved by changing the material from Type 304 stainless steel to Type 316L stainless steel and by changing the welding method from tungsten inert gas welding to electron beam welding. With the optimized design, the capsule was successfully irradiated at low temperatures of <100°C for up to eight cycles (6075 MWd) at HANARO.

Liquid Steel at Low Pressure: Experimental Investigation of a Downward Water Air Flow

In the continuous casting of steel controlling the steel flow rate to the mould is critical because a well-defined flow field at the mould level is essential for a good quality of the cast product. The stopper rod is a commonly used device to control this flow rate. Agglomeration of solid material near the stopper rod can lead to a reduced cross section and thus to a decreased casting speed or even total blockage (“clogging”). The mechanisms causing clogging are still not fully understood. Single phase considerations of the flow in the region of the stopper rod result in a low or even negative pressure at the smallest cross section. This can cause degassing of dissolved gases from the melt, evaporation of alloys and entrainment of air through the porous refractory material. It can be shown that the degassing process in liquid steel is taking place mainly at the stopper rod tip and its surrounding.The steel flow around the stopper rod tip is highly turbulent. In addition refractory material has a low wettability to liquid steel. So the first step to understand the flow situation and transport phenomena which occur near the stopper is to understand the behaviour of this two phase (steel, gas) flow. To simulate the flow situation near the stopper rod tip, water experiments are conducted using a convergent divergent nozzle with three different wall materials and three different contact angles respectively. These experiments show the high impact of the wettability of the wall material on the actual flow structure at a constant gas flow rate.

Nanofocus x-ray diffraction and cathodoluminescence investigations into individual core–shell (In,Ga)N/GaN rod light-emitting diodes

Employing nanofocus x-ray diffraction, we investigate the local strain field induced by a five-fold (In,Ga)N multi-quantum well embedded into a GaN micro-rod in core–shell geometry. Due to an x-ray beam width of only 150 nm in diameter, we are able to distinguish between individual m-facets and to detect a significant in-plane strain gradient along the rod height. This gradient translates to a red-shift in the emitted wavelength revealed by spatially resolved cathodoluminescence measurements. We interpret the result in terms of numerically derived in-plane strain using the finite element method and subsequent kinematic scattering simulations which show that the driving parameter for this effect is an increasing indium content towards the rod tip.

Experimental and numerical investigation of the influence of thermal boundary conditions on premixed swirling flame stabilization

This paper focuses on the experimental and numerical investigation of the shape taken by confined turbulent CH4/H2/air premixed flames stabilized over a bluff-body swirling injector. Two configurations, which correspond to two levels of H2 enrichment in the CH4/H2 fuel blend, are investigated. Experiments show that high H2 concentrations promote M flame shapes, whereas V flame shapes are observed for lower values of H2 enrichment. In both cases, non-reacting and reacting flow Large Eddy Simulation (LES) calculations were performed. Numerical results are compared with detailed velocimetry measurements under non-reacting and reacting conditions, OH-laser induced fluorescence and OH* chemiluminescence measurements. All temperatures of solid walls of the experimental setup including the combustor dump plane, the injector central rod tip, the combustor sidewalls and the quartz windows were also characterized. Assuming a fully adiabatic combustion chamber, LES always predicts an M flame shape and does not capture the V to M shape transition observed in the experiments when the hydrogen concentration in the fuel blend is increased. By accounting for non-adiabaticity using measured thermal boundary conditions, simulations predict the correct flame stabilization for both V and M flames and show a good agreement with experiments in terms of flame shape. Key features that need to be included in non-adiabatic simulations are finally stressed out.

Joint-Angle Coordination Patterns Ensure Stabilization of a Body-Plus-Tool System in Point-to-Point Movements with a Rod.

When performing a goal-directed action with a tool, it is generally assumed that the point of control of the action system is displaced from the hand to the tool, implying that body and tool function as one system. Studies of how actions with tools are performed have been limited to studying either end-effector kinematics or joint-angle coordination patterns. Because joint-angle coordination patterns affect end-effector kinematics, the current study examined them together, with the aim of revealing how body and tool function as one system. Seated participants made point-to-point movements with their index finger, and with rods of 10, 20, and 30 cm attached to their index finger. Start point and target were presented on a table in front of them, and in half of the conditions a participant displacement compensated for rod length. Results revealed that the kinematics of the rod's tip showed higher peak velocity, longer deceleration time, and more curvature with longer rods. End-effector movements were more curved in the horizontal plane when participants were not displaced. Joint-angle trajectories were similar across rod lengths when participants were displaced, whereas more extreme joint-angles were used with longer rods when participants were not displaced. Furthermore, in every condition the end-effector was stabilized to a similar extent; both variability in joint-angle coordination patterns that affected end-effector position and variability that did not affect end-effector position increased in a similar way vis-à-vis rod length. Moreover, the increase was higher in those conditions, in which participants were not displaced. This suggests that during tool use, body and tool are united in a single system so as to stabilize the end-effector kinematics in a similar way that is independent of tool length. In addition, the properties of the actual trajectory of the end-effector, as well as the actual joint-angles used, depend on the length of the tool and the specifics of the task.

Localized neutron flux assessment and verification studies using MCNPX PWR full core model

The existence of significant local intra-assembly and azimuthal neutron flux variations at or around PWR control rod fingers and which would eventually not be captured by lower order transport deterministic reactor analysis methods, was examined using simplified full-core Monte Carlo calculations. The locations of specific interest were the clad surfaces and absorber material zones around the tips of partially inserted control rods in controlled assemblies located at various core locations. A fixed-source option was adopted in order to reduce the modeling efforts and computational costs. However, the validity of the fixed-source approach for predictions of the local flux distributions was verified by comparisons against corresponding calculations performed in eigenmode and against deterministic CASMO/SIMULATE solutions. Noticeable azimuthal neutron flux variations up to ∼30% were observed but only for the thermal energy range. For the fast (>1MeV) neutron flux, the predicted azimuthal variations were found to be bounded by an upper value of about ∼10%. On the other hand, significant planar flux non-uniformities between individual control rods within a controlled assembly were seen for all energies. Hence, in addition of having allowed for a strengthened knowledge on the behavior of local flux variations around PWR control rods, these results also provide a first assessment of the likely uncertainty level in control rod tip fluence estimations based on lower resolution deterministic reactor analysis codes.

Nonlinear argumental oscillators: A few examples of modulation via spatial position

Under certain conditions, an oscillator can enter a stable regime when submitted to an external harmonic force whose frequency is far from the natural frequency of the oscillator. This may happen when the external force acts on the oscillator in a way which depends on the oscillator's spatial position. This phenomenon is called “argumental oscillation”. In this paper, six argumental oscillators are described and modeled, and experimental results are given and compared to numerical simulations based on the models. A polar Van der Pol representation, with embedded time indications, is used to allow a precise comparison. The pendulums are modeled as Duffing oscillators. The six models are based on various pendulums excited by spatially localized magnetic-field sources consisting of wire coils. Each pendulum receives the excitation via a steel element, or a permanent magnet, fitted at the tip of the pendulum's rod. The spatial localization induces another nonlinearity besides the Duffing nonlinearity. A control system allowing a real-time Van der Pol representation of the motion is presented. Attractors are brought out from experimental results.

Effect of variation in main field and nanoparticle content on the partial discharge characteristics of polypropylene nanocomposites

The effect of varying the main and local field on the partial discharge characteristics of polypropylene film is studied by analyzing the temporal behavior of partial discharge parameters. In the first set of experiments, keeping the applied voltage constant, the gap spacing is varied altering the applied field. When the gap is relatively small, discharges appear in quick succession deepening the craters in front of the rod tip where space charges are widely distributed, precipitating discharges of wide range of amplitudes. At relatively larger spacing, the discharge behavior is largely controlled by electric field distribution. In the fixed gap experiments, the local field is varied by introducing polymer nanocomposites that have different filler content. For a fixed gap and constant voltage, discharge magnitudes are lower in samples with nanofiller content below the percolation threshold than in the base polymer. The scatter in discharge magnitudes is lower in samples with nanoparticle content below the percolation threshold than in samples with nanofiller content above the threshold. The major conclusion is the maximum advantage of adding nanofillers is gained only when the particle content is below the percolation threshold.

Experimental research on lightning shielding performance of large scaled UHV transmission line

In actual operation, the shielding failure rate of UHV transmission line is much higher than that in simulation, so it is crucial to study the lightning shielding performance by experimental research. The testing UHV transmission line model is scaled down in the ratio of 12.5 which is relatively large comparing to other testing models. Two kinds of negative switching impulse waveform were applied to HV rod to simulate the lightning descending leader. The probability of transmission line being stroked was calculated statistically by recording more than two thousand discharges and the factors that affecting the discharge probability were studied through contrast tests. The results show that the grounding condition, DC bias, the protection angle, the switching impulse voltages have an influence on the discharge probability, breakdown voltage and breakdown time. The spatial boundary of shielding failure area was determined in the middle of the span. The upper and lower spatial boundary and the distance between them increased with the increasing of the lateral distance between HV rod tip and transmission line model simultaneously.

Measurements of driving energy in SPT and various dynamic cone penetration tests

Driving energy was measured in a standard penetration test (SPT) and 12 types of dynamic cone penetration tests (DCPTs) having different configurations for the hammer, driving rod, anvil and cone tip. The driving energy transferred from the free falling hammer to the driving rod was estimated from the measurements of strain and acceleration below the anvil. Basically, the driving energy was estimated for 21 successive blows in order to obtain the mean value, the standard deviation (σ) and the coefficient of variance (COV) in the SPT and DCPTs. The dynamic cone resistance, qdyn, was estimated from the driving energy, the corresponding set per blow, and masses of the hammer and the total rods. Thus, the estimated dynamic cone resistance was compared with the static cone resistance, qt, from a cone penetration test (CPT). The main objective of this report is to provide information on the driving efficiency in the SPT and each DCPT. The mean values for ef in the tests ranged from 52% to 76%. The values of COV for ef ranged from 0.024 to 0.265. Even though the test results are limited, the dynamic cone resistance, qt, estimated from the dynamic measurements were relatively good measures of the cone resistance from the CPT, showing the importance of the dynamic measurement in the SPT and DCPTs.In addition, possible factors influencing the driving efficiency, such as the hammer mass, the configuration of the driving rod (solid or hollow), the ratio of the diameter of the anvil and the diameter of the hammer, and the existence of a cushion or cushions between the anvil and the hammer, are discussed on the basis of the limited test results.

Visualization of Liquid Metal Two-phase Flows in a Physical Model of the Continuous Casting Process of Steel

We present an experimental study concerned with investigations of the two-phase flow in a mock-up of the continuous casting process of steel. A specific experimental facility was designed and constructed at HZDR for visualizing liquid metal two-phase flows in the mold and the submerged entry nozzle (SEN) by means of X-ray radioscopy. This setup operates with the low melting, eutectic alloy GaInSn as model liquid. The argon gas is injected through the tip of the stopper rod into the liquid metal flow. The system operates continuously under isothermal conditions. First results will be presented here revealing complex flow structures in the SEN widely differing from a homogeneously dispersed bubbly flow. The patterns are mainly dominated by large bubbles and large-area detachments of the liquid metal flow from the inner nozzle wall. Various flow regimes can be distinguished depending on the ratio between the liquid and the gas flow rate. Smaller gas bubbles are produced by strong shear flows near the nozzle ports. The small bubbles are entrained by the submerged jet and mainly entrapped by the lower circulation roll in the mold. Larger bubbles develop by coalescence and ascend toward the free surface.

초저온 피스톤 펌프의 성능 향상에 관한 연구

In order to develop a universal cryogenic piston pump of small size for increasing utilization of liquid hydrogen, dynamic compression performance of piston pump were evaluated and improvements were also discussed for piston rod and piston tip. The cryogenic piston pump has crosshead structure and inclined cup shape piston tip. As the results, it was found that i) insulation of heat flow from piston-rod part is required for stable operation ii) improving the self-clearance adjustment effect of piston tip and reducing piston eccentricity were desirable to promote pumping pressure and operating range.

Rod-to-hook transition for extracellular flagellum assembly is catalyzed by the L-ring-dependent rod scaffold removal.

In Salmonella, the rod substructure of the flagellum is a periplasmic driveshaft that couples the torque generated by the basal body motor to the extracellular hook and filament. The rod subunits self-assemble, spanning the periplasmic space and stopping at the outer membrane when a mature length of ~22 nm is reached. Assembly of the extracellular hook and filament follow rod completion. Hook initiation requires that a pore forms in the outer membrane and that the rod-capping protein, FlgJ, dislodges from the tip of the distal rod and is replaced with the hook-capping protein, FlgD. Approximately 26 FlgH subunits form the L-ring around the distal rod that creates the pore through which the growing flagellum will elongate from the cell body. The function of the L-ring in the mature flagellum is also thought to act as a bushing for the rotating rod. Work presented here demonstrates that, in addition to outer membrane pore formation, L-ring formation catalyzes the removal of the FlgJ rod cap. Rod cap removal allows the hook cap to assemble at the rod tip and results in the transition from rod completion in the periplasm to extracellular hook polymerization. By coupling the rod-to-hook switch to outer membrane penetration, FlgH ensures that hook and filament polymerization is initiated at the appropriate spatial and temporal point in flagellar biosynthesis.

27. Advances towards standardised freezing protocols

In the field of cryopreservation cells are stored at cryogenic temperatures in order to maintain their quality after thawing. Lowering the temperature reduces the metabolism of cells and therefore can prevent their loss of quality over time. During the freezing process different parameters have been identified as cell damaging mechanisms [1] . Thus, a correct setting of process parameters including the cooling and warming rate, nucleation temperature ( T n ), sample geometry, as well as type and concentration of cryoprotective agents can reduce cellular damage and result in high quality output after freezing. For comparison of the qualities of different biological specimens, freezing protocols and viability analyses need to be standardised. Most of the earlier studies did not account for the control of all process parameters, especially the nucleation temperature [1] . Therefore, the aim of this study was to control all possible process parameters during freezing of human endothelial cells (ECs) and mesenchymal stem cells (MSCs) of the marmoset monkey using different experimental methods. A standardised freezing protocol was developed which is based on our earlier experimental results [2] . The protocol includes a cooling rate of 5 K/min, heating rate of 100 K/min, 5% (v/v) DMSO and a nucleation temperature of −8 °C. The first method used was a μ -freezer (CM2000, Carburos Metalicos) where 1 mL cell suspensions were frozen in cryovials. For the control of the nucleation temperature a new setup was developed which is based on nucleation via Peltier elements [3]. A second method used a commercially available cryomicroscopic setup to visualise the cells in suspension which involves a LINHAM cryostage FDCS 196. and a digital camera (Retiga, QImaging). The temperature of the samples was controlled from 40 to −196 °C. The manual cell seeding process required the removal of the lid of the cryostage when a cooled copper rod touches the supercooled sample. To overcome this limitation, we developed a new seeding device for cryomicroscopic investigations of aqueous samples. This device applies a copper rod which is cooled via liquid nitrogen flushed heat exchanger. A USB camera is used to identify the position of the copper rod tip during an initial local calibration procedure which is electronically stored. Thus, the system can automatically calculate the distance to the sample. Nucleation is induced by a liquid nitrogen cooled copper rod which is positioned towards the specimen by a step motor system. The device allows for the control of the nucleation temperature at cooling rates up to 10 K/min with an accuracy of ±0.2 K. Both construction designs allow the control of the nucleation temperature and contribute to a further standardisation of freezing protocols. After cell freezing, the quality of the protocol was determined using staining methods based on trypan blue, calcein AM and ethidium homodimer. As a general quality test the absolute viability was determined which is defined as the ratio of viable cell number after freezing to the total cell number before freezing. Using this method, the viability of ECs after freezing was 90%. After thawing, MSCs were tested for proliferation and differentiation into the osteogenic and adipogenic lineage. To achieve a standardisation of freezing protocols we propose to control all process parameters including the nucleation temperature and the use of the absolute viability as a general method for quality comparison of different cellular specimens after freeze/thawing.

Does the magnetic field of a magnetic stirrer in an optical aggregometer affect concurrent platelet aggregation?

Platelets are subjected to extremely low frequency electromagnetic fields during standard aggregometry measurements owing to the use of a magnetic stir bar in the instrument. This study evaluates the effects of this magnetic field exposure on platelet aggregation by comparing the results obtained in a modified aggregometer. Blood samples from healthy volunteers were anticoagulated using citrate or heparin. Platelet-rich plasma (PRP) samples were prepared. A mechanical stirring device was attached to the aggregometer instead of the magnetic stir bar system. The PRP samples were stirred using a stirring rod tip that did not produce any magnetic fields in one channel of the aggregometer; in the other channel, a stirring rod carrying a small magnet at its tip was used. As a result, a magnetic field in the extremely low frequency range and in the amplitude range of 1.9-65 mT was applied to the platelets assigned to the channel where the magnetic stirring rod tip was used. Aggregation was induced using adenosine diphosphate (ADP), collagen, or epinephrine. The slopes, maximum aggregation values, and areas under the aggregation curves were compared between the magnetic and neutral stirring rod tip groups. For samples stirred with the magnetic stirring rod tip, a significant decrease was observed in 12 of the 14 parameters evaluated for aggregations induced with ADP or collagen compared to the neutral stirring rod tip, regardless of the method used for anticoagulation. This observation indicates that the magnetic stir bars used in standard aggregometry may significantly alter aggregation parameters and platelets may be possible targets of electromagnetic fields.

Dynamical Analysis on a Mass at the Tip of a Flexible Rod on a Rotating Base

Abstract: A dynamical analysis on a mass fixed at the tip of a massless flexible rod mounting on a rotating rigid body is presented in which the motion of the mass is kept in the plane of rotation as small deformation of the rod is assumed. For the rigid body undergoing a constant angular velocity the centrifugal forces and Coriolis force on the mass are considered. There exist two dynamic frequencies in which the first order dynamic frequency decreases with rotational velocity up to zero that is associated with a limit rotational velocity of the system. The motion trajectories of the mass in the rotational plane at different rotational velocities exhibit multiple traces with respect to the conventional line trace and may be split into the non-eccentric and eccentric portions. With a view on the change of amplitudes a critical rotational velocity is discussed.

Influence of Operation Procedures on Vicat Softening Temperature of Thermoplastic Materials

Vicat softening temperature (VST) is one of the most important parameters to evaluate heat resistance of thermoplastic materials. However, the initial test temperature is difficult to control, which may reduce the testing efficiency and the precision of VST. Moreover, according to the procedure of GB/T 1633-2000, the specimen should be placed horizontally under the indenting tip of unloaded rod for 5min. After that, add a sufficient weight to the weight-carrying plate, and then set the penetration indicator to zero to start the experiment. However, the waiting period between adding the extra mass and starting the test may be different during the real operation. Such longer or shorter waiting periods can also influence the tested VST. In this paper, ultra-high molecular weight polyethylene (UHMWPE) was used to discuss the influence of initial temperature and waiting period on its final VST. The results show that, in order to satisfy the practices of standard GB/T 1633-2000, the initial temperature and the waiting period should not exceed 40°C and 25min, respectively.

Fracture in long bones stabilised by telescopic intramedullary rods in patients with osteogenesis imperfecta

We investigated the fracture-free survival of long bones stabilised by a telescopic intramedullary rod (TIMR) in patients with osteogenesis imperfecta with respect to the remodelling status of fracture or osteotomy sites and TIMR regions, in order to identify risk factors for fracture. A total of 44 femora and 28 tibiae in 25 patients with a mean age of 5.0 years (1.9 to 10.5) at presentation were studied. There were six patients with Sillence type I, five with type III, 13 with type IV and one with type V osteogenesis imperfecta. All received bisphosphonate treatment at the same stage during the mean follow-up of 7.3 years (0.5 to 18.1). The fracture-free survival was estimated at 6.2 years (95% confidence interval 5.1 to 7.3) by Kaplan-Meier analysis. More than half the fracture or osteotomy sites remained in a less-remodelled state at the latest follow-up or time of fracture. Of the 33 fractures, 29 (87.9%) occurred in long bones containing a less-remodelled site, and these fractures were located at this site. The relative fracture risk at the rod tip was significantly greater than in any other TIMR region (p < 0.001), and this was higher in bone segments having a less-remodelled site. This study shows a persistent fracture risk in TIMR-stabilised long bones, especially at less-remodelled fracture or osteotomy sites and at the rod tip.