Mm In Outer Diameter Research Articles

Polymer-clad silica fibers for tailoring modal area and dispersion.

We demonstrate higher-order-mode (Aeff up to ∼2000 μm2) propagation in a 100μm outer diameter pure-silica fiber with a low-index polymer jacket commonly used for fiber laser pump guidance. This simple structure obviates the need for complex designs deemed necessary for realizing large-mode-area fibers. Modes ranging from HE1,12 to HE1,22 were found to propagate stably over 15m in this fiber. The index step is approximately 4 times larger than that obtained with fluorine down doping; thus the fiber supports even higher-order modes, which may have implications for building rare-earth-doped fiber lasers or achieving enhanced dispersion tunability for high-energy fiber nonlinear phenomena.

Development of a compact cryocooler system for high temperature superconductor filter application

Seeking a higher specific power of the pulse tube cryocooler is an important trend in recent studies. High frequency operation (100Hz and higher), combined with co-axial configuration, serve as a good option to meet this requirement. This paper introduces a high efficiency co-axial pulse tube cryocooler operating at around 100Hz. The whole system weighs 4.3kg (not including the radiator) with a nominal input power of 320W, namely, power density of the system is around 74W/kg. The envelop dimensions of the cold finger itself is about 84mm in length and 23mm in outer diameter. Firstly, numerical model for designing the system and some simulation results are briefly introduced. Distributions of pressure wave, the phase difference between the pressure wave and the volume flow rate and different energy flow are presented for a better understanding of the system. After this, some of the characterizing experimental results are presented. At an optimum working point, the cooling power at 80K reaches 16W with an input electric power of 300W, which leads to an efficiency of 15.5% of Carnot.

Trapped Field Characteristics and Fracture Behavior of REBaCuO Bulk Ring During Pulsed Field Magnetization

We have performed pulsed field magnetization (PFM) for the GdBaCuO ring bulk (60 mm in outer diameter, 36 mm in inner diameter, and 17 mm in thickness) with an aluminum alloy bandage at 65 K. When a magnetic pulsed field over 3 T was applied, a fracture was confirmed in the bulk by the trapped field profile. Using a numerical simulation by a finite-element method, the trapped field and the hoop (σ θ ) and radial (σ r ) stresses were analyzed. A huge compressive stress concentrated at the inner peripheral edge of the ring bulk mainly by the thermal contraction. The additional compressive stress was applied by the flux-pinning-induced magnetostriction around the maximum field during PFM. The mechanical reinforcement in the inner periphery part of the ring bulk must be considered during PFM using a cylinder.

CTOD‐R curves of the metal‐clad interface of API X52 pipes cladded with an Inconel 625 alloy by welding overlay

AbstractCrack‐tip opening displacement resistance curves (CTOD‐R) of the substrate/cladding interface of an API 5 L X52 steel pipe internally coated with Inconel 625 applied by TIG (GTAW) welding were experimentally evaluated. A small pipe section with 168 mm of outer diameter and 22.5 mm of thickness was internally coated with a 15 mm thick layer of Inconel 625 corrosion resistant alloy. Tension test specimens were obtained from both substrate and cladding, as well as compact tension test specimens (C(T)) for the evaluation of CTOD‐R curves. The fracture testing specimens were notched at the interface in RL orientation. In addition to fracture and tensile testing, microstructural characterization was conducted at the interface using optical microscopy (OM) and scanning electron microscopy (SEM). Qualitative chemical composition scanning and microhardness determination were also performed. The results indicated high fracture toughness for the substrate/cladding interface and the absence of low toughness regions at the interface of the tested samples.

Design and Testing of a Motor-Based Capsule Robot Powered by Wireless Power Transmission

This paper presents a motor-based capsule robot powered by wireless power transmission, a device with a small size of $\Phi$ 13 mm $ \times$ 42 mm for exploring the intestinal tract. The active locomotion of the capsule robot is achieved with an inchworm mechanism, which consists of two expanding devices at both ends and a middle extensor. The expanding device features a large expanding diameter range of 13 to 29.9 mm by adopting a four-bar linkage and it is sealed by two O-rings. Based on the Hertz contact theory, the design parameters of the two O-rings (i.e., wire diameter, hardness, and compression ratio) were optimized, and the optimized O-rings caused 17.6% torque loss at most. To take full advantage of the space in the inchworm mechanism, a novel hollow-cylinder-like 3-D receiving coil was proposed, which employed a combined ferrite core and measured 6 mm in inner diameter, 12.9 mm in outer diameter, and 11.5 mm in length. By selecting appropriate numbers of turns for the 3-D coils, the output power fluctuation of the receiving coil was minimized within a range of 485.7 to 1459.2 mW. Finally, the system performance of the capsule robot was successfully tested in an ex vivo intestine using a fabricated prototype with inspection function.

Pathologic electrographic changes after experimental traumatic brain injury.

To investigate possible electroencephalography (EEG) correlates of epileptogenesis after traumatic brain injury (TBI) using the fluid percussion model. Experiments were conducted on adult 2- to 4-month-old male Sprague-Dawley rats. Two groups of animals were studied: (1) the TBI group with depth and screw electrodes implanted immediately after the fluid percussion injury (FPI) procedure, and (2) a naive age-matched control group with the same electrode implantation montage. Pairs of tungsten microelectrodes (50 μm outer diameter) and screw electrodes were implanted in neocortex inside the TBI core, areas adjacent to TBI, and remote areas. EEG activity, recorded on the day of FPI, and continuously for 2 weeks, was analyzed for possible electrographic biomarkers of epileptogenesis. Video-EEG monitoring was also performed continuously in the TBI group to capture electrographic and behavioral seizures until the caps came off (28-189 days), and for 1 week, at 2, 3, and 6 months of age, in the control group. Pathologic high-frequency oscillations (pHFOs) with a central frequency between 100 and 600 Hz, were recorded from microelectrodes, beginning during the first two post-FPI weeks, in 7 of 12 animals in the TBI group (58%) and never in the controls. pHFOs only occurred in cortical areas within or adjacent to the TBI core. These were associated with synchronous multiunit discharges and popSpikes, duration 15-40 msec. Repetitive pHFOs and EEG spikes (rHFOSs) formed paroxysmal activity, with a unique arcuate pattern, in the frequency band 10-16 Hz in the same areas as isolated pHFOs, and these events were also recorded by screw electrodes. Although loss of caps prevented long-term recordings from all rats, pHFOs and rHFOSs occurred during the first 2 weeks in all four animals that later developed seizures, and none of the rats without these events developed late seizures. pHFOs, similar to those associated with epileptogenesis in the status rat model of epilepsy, may also reflect epileptogenesis after FPI. rHFOSs could be noninvasive biomarkers of epileptogenesis.

In Vivo Magnetic Stimulation of Rat Sciatic Nerve With Centimeter- and Millimeter-Scale Solenoid Coils.

Previous reports of magnetic stimulation of the peripheral nervous system (PNS) used various coil geometries, all with outer diameters larger than 35 mm, and stimulation energies in the 50 J range to evoke neural excitation. Recent reports of central nervous system (CNS) activation used sub-mm-scale solenoid coils with mJ energy levels. The goal of this study was to translate the lower energy levels from the CNS to the PNS via using smaller coils placed in closer proximity to the neural tissue. Such a performance improvement would advance the state of the art of magnetic stimulation and provide a path towards new neuroprosthetic devices. Primarily, we investigated the range of coil outer diameters from 25 mm down to 5 mm to better understand the dependence of coil diameter on energy required for PNS activation. Nine cm- and mm-scale copper solenoid coils, with various resistances, inductances, inner and outer diameters, and heights were compared by quantizing neuromuscular responses to magnetic stimulation via capacitive discharge excitation of rat sciatic nerves in vivo. Additionally, the effects of stimulus duration and coil position were investigated. As opposed to prior work, this study compares a subset of stimulation parameters in an intact nerve preparation, and shows that magnetic stimulation with coils that abut the nerve is a reliable, effective method of neuromuscular stimulation. Although we observed different energies required for neuromuscular activation depending on the coil and excitation parameters used, for the experimental configuration, devices, and stimulus waveform shapes presented in this manuscript, no systematic dependence of PNS activation on coil diameter was found, even for the mm-scale coils investigated herein. However, there was a clear relationship between discharge circuit capacitance and energy required to evoke a neuromuscular response. Coils approximately 12 mm in outer diameter and larger consistently evoked responses, whereas coils 5 mm in outer diameter did not. Furthermore, we observed meaningful neuromuscular excitation when stimulating with energies as low as 20 J. Although this is an improvement over prior work, it is still orders of magnitude greater than the energy required for conventional electrical stimulation, suggesting that these devices are presently not suitable for use in an application requiring continued pulsed stimulation. Nevertheless, these devices are suitable for basic research and as clinical tools that infrequently stimulate, such as in diagnostic applications.

Variation in electrosurgical vessel seal quality along the length of a porcine carotid artery.

Electrosurgical vessel sealing has been demonstrated to have benefits for both patients and practitioners, but significant variation in the strength of the seal continues to be a concern. This study aims to examine the variation in electrosurgical seal quality along the length of a porcine common carotid artery and explore the relationships between seal quality, vessel size and morphology. Additionally, the study aimed to investigate the minimum safety threshold for successful seals and the influence of vessel characteristics on meeting this requirement. A total of 35 porcine carotid arteries were sealed using the PlasmaKinetic Open Seal device (Gyrus). Each seal was burst pressure tested and a sample taken for staining with elastin van Gieson’s stain, with morphological quantification using image processing software ImageJ. With increasing distance from the bifurcation, there was an increase in seal strength and a reduction in both elastin content and vessel outer diameter. A significant correlation was found between burst pressure with both outer diameter (p < 0.0001) and elastin content (p = 0.001). When considering the safe limits of operation, vessels of less than 5 mm in outer diameter were shown to consistently produce a seal of a sufficient strength (burst pressure > 360 mmHg) irrespective of vessel morphology.

Two-photon polymerization of a branched hollow fiber structure with predefined circular pores

Porous fiber structures are of great concern to many fields of life-science engineering, but require a complex assembly processes that have geometric constraints. For this reason, tremendous efforts were expended in recent years to develop micro-/nano fabrication techniques. We report on the 3D structuring of a 3.5 mm long branched hollow fiber with 150 μm outer diameter and predefined circular pores (diameter: 30 μm). The investigated process is based on two-photon polymerization (2PP) of the UV curing resin OrmoComp®. The incident light of a femtosecond pulsed laser at 790 nm wavelength is used to generate the structure. Utilizing the non-linear behavior of two-photon absorption due to a tightly focused, high-intensity laser beam allows the local fabrication of three-dimensional structures in the photoresist. Voxels fabricated by 2PP are studied by controlling average laser power and exposure time. The appropriate average pulse energy and writing speed are determined to apply the optimal exposure parameters concerning the geometric accuracy and overall quality of the structure. The 2PP direct laser writing process is employed to generate the hollow fiber at an average laser power of 105 mW, and a writing speed of 5.0 mm/s. Water flowing through the fiber provides evidence that the core is hollow.

Bump-Type Foil Bearings and Flexure Pivot Tilting Pad Bearings for Oil-Free Automotive Turbochargers: Highlights in Rotordynamic Performance

Oil-free turbochargers (TCs) require gas bearings in compact units of enhanced rotordynamic stability, mechanical efficiency, and improved reliability with reduced maintenance costs compared with oil-lubricated bearings. Implementation of gas bearings into automotive TCs requires careful thermal management with accurate measurements verifying model predictions. Gas foil bearings (GFBs) are customarily used in oil-free microturbomachinery because of their distinct advantages including tolerance to shaft misalignment and centrifugal/thermal growth, and large damping and load capacity compared with rigid surface gas bearings. Flexure pivot tilting pad bearings (FPTPBs) are widely used in high-performance turbomachinery since they offer little or no cross-coupled stiffnesses with enhanced rotordynamic stability. The paper details the rotordynamic performance and temperature characteristics of two prototype oil-free TCs; one supported on foil journal and thrust bearings and the other one is supported on FPTP journal bearings and foil thrust bearings of identical sizes (outer diameter (OD) and inner diameter (ID)) with the same aerodynamic components. The tests of the oil-free TCs, each consisting of a hollow rotor (∼0.4 kg and ∼23 mm in OD at the bearing locations), are performed for various imbalances in noise, vibration, and harshness (NVH; i.e., cold air driven rotordynamics rig) and gas stand test facilities up to 130 krpm. No forced cooling air flow streams are supplied to the test bearings and rotor. The measurements demonstrate the stable performance of the rotor–gas bearing systems in an ambient NVH test cell with cold forced air into the turbine inlet. Post-test inspection of the test FPTPGBs after the hot gas stand tests evidences seizure of the hottest bearing, thereby revealing a notable reduction in bearing clearance as the rotor temperature increases. The compliant FPTPGBs offer a sound solution for stable rotor support only at an ambient temperature condition while demonstrating less tolerance for shaft growth, centrifugal, and thermal, beyond its clearance. The current measurements give confidence in the present GFB technology for ready application into automotive TCs for passenger car and commercial vehicle applications with increased reliability.

Gel phantom study of a cryosurgical probe with a thermosiphon effect and liquid nitrogen-cooled aluminum thermal storage blocks.

Cryosurgery is a minimally invasive treatment for certain types of cancers. Argon-based cryosurgical devices are available at present, however a large compressed gas cylinder with the pressure of 300 atmospheres is needed. To overcome these drawbacks, we developed a new cryosurgical probe measuring about 50 cm in length with separate lumens inside for liquid and gaseous ethylene to be used as a thermosiphon and liquid nitrogen-cooled aluminum thermal storage blocks. The probe needle was 8 cm in length and 3 mm in outer diameter. To investigate the freezing capabilities of our new cryosurgical system we inserted the needle 5cm into a poly-acrylamide gel phantom warmed to 36.5 ℃. Thermal storage blocks made of aluminum, cooled at -196 ℃ in liquid nitrogen, were attached to the condenser of the probe and replaced with thermal storage blocks every 4 to 5 minutes to compensate for warming. We took digital camera images of the ice ball at the needle and measured the temperature in certain locations of the cryoprobe. Ice ball formation started at one minute after cooling. The sizes (longest diameter × minimum diameter) at 10, 20 and 30 minutes after the start of the procedure were 4.5×2.1, 4.5×3.1 and 4.6×3.7 cm, respectively. During the procedure the minimum temperature of the condenser was -85 ℃ and the needle was -65 ℃. This newly developed compact cryosurgical probe with thermosiphon effect and cooled thermal storage blocks created an ice ball that can be used for cryosurgery within 20 minutes.

Fabrication of Low-Invasive Patch Glucose Sensors

1. IntroductionRecently, implantable glucose sensors for continuous glucose monitoring (CGM) are provided significant advantage on diabetic health care, since it not only lower the physical and mental load on glucose measurement, but also present continuous glucose trend, which is useful for treatment evaluation. However, since the length of sensor device inserted in skin is about 1 cm, development of lower invasive CGM system is expected for the improvement of diabetic patients' quality of life. In this study, a fine needle tube type glucose sensor, which has sensing region at the tip of a fine tapered electrode, was proposed. The schematic illustration of such glucose sensor is shown in Fig. 1. Since the sensing region is at the tip of tapered electrode, it only requires the sensor tip to be implanted in the tissue for glucose monitoring, which makes it possible to perform as a patch type sensor instead of implanting sensor. Fine platinum-iridium alloy wire was placed inside the tapered PEEK tube and glucose oxidase (GOx) was immobilized on the surface of platinum electrode by using the combination of electrodeposition and electropolymerization technique. Properties of the obtained sensor were evaluated mainly by in vitro measurement.2．ExperimentalPt-Ir alloy wire (0.17 mm in diameter) was fixed in a PEEK tube (0.20 mm in inner diameter and 0.8 mm in outer diameter). The prepared assembly was mechanically polished to form a fine tapered needle structure. According to the procedure proposed by Wilson's group [1], the biosensor was prepared.The amperometric responses of the prepared electrodes to glucose were examined at 40°C in a 0.1 M PBS (pH 7.4) containing 0.1 M NaCl, by measuring the electrooxidation current at a potential of 0.6 V (vs. Ag/AgCl).3．ResultsCurrent-time response of the prepared electrode was investigated. The response current increased with increasing concentration of glucose. Response current provided good linear relationship with glucose concentration. Variation of response in time on the prepared electrode was investigated for two weeks. The response of the electrode was measured at 40°C and stored in phosphate buffer at 4°C when not in use. After initial increase of response current for few days, the electrode provided stable response current.(1) N. Matsumoto, X. Chen and G. S. Wilson, Anal Chem, 74, 368 (2002). Figure 1

Su1591 Magnetic Resonance Cholangio-Pancreatography (MRCP) Has Low Sensitivity in Diagnosing Biliary Strictures After Liver Transplantation: a Single Tertiary Care Center Experience

Su1591 Magnetic Resonance Cholangio-Pancreatography (MRCP) Has Low Sensitivity in Diagnosing Biliary Strictures After Liver Transplantation: a Single Tertiary Care Center Experience

Su1590 Role of the Direct PerOral Cholangioscopy Using an Ultra-Slim Endoscope After Endoscopic Extraction of Choledocholithiasis for Detecting Small Bile Duct Lesions Obscure in Conventional Imagings

Su1590 Role of the Direct PerOral Cholangioscopy Using an Ultra-Slim Endoscope After Endoscopic Extraction of Choledocholithiasis for Detecting Small Bile Duct Lesions Obscure in Conventional Imagings

Magnetocardiogram measured by fundamental mode orthogonal fluxgate array

Magnetocardiography (MCG) of healthy volunteers has been measured by using a fundamental mode orthogonal fluxgate magnetometer array of 32 channels in a magnetic shielded room (MSR). Sensor heads, which are employed, consist of a 45 mm long U-shaped amorphous wire core and a 1000-turn solenoid pick-up coil of 30 mm in length and 3 mm in outer diameter. The excitation current of 100 kHz with large dc bias current is fed directly into wire cores, which are connected in series, whereas the signal detection circuit is provided to each of the sensor heads. A special technique to avoid mutual interaction between sensor heads is implemented, where all the sensor heads are excited synchronously by using a single ac source. A 2-D array having 32 sensors with 4 cm grid spacing was used to measure MCG signals inside an MSR. Measured data from each channel were first filtered (0.16–100 Hz pass band), then averaged for 2 min synchronously with electrocardiogram's peaks taken from both hands. Noise remaining after the average is about 1.8 pTrms for the band-width of 0.16–100 Hz. The QRS complex and the T-wave are clearly detected.

Bone regeneration of hydroxyapatite/alumina bilayered scaffold with 3 mm passage-like medullary canal in canine tibia model.

The aim of this study was to evaluate the bone regeneration of hydroxyapatite (HA)/alumina bilayered scaffold with a 3 mm passage-like medullary canal in a beagle tibia model. A porous HA/alumina scaffold was fabricated using a polymeric template-coating technique. HA/alumina scaffold dimensions were 10 mm in outer diameter, 20 mm in length, and with either a 3 mm passage or no passage. A 20 mm segmental defect was induced using an oscillating saw through the diaphysis of the beagle tibia. The defects of six beagles were filled with HA/alumina bilayered scaffolds with a 3 mm passage or without. The segmental defect was fixated using one bone plate and six screws. Bone regeneration within the HA/alumina scaffolds was observed at eight weeks after implantation. The evaluation of bone regeneration within the scaffolds after implantation in a beagle tibia was performed using radiography, computerized tomography (CT), micro-CT, and fluorescence microscopy. New bone successfully formed in the tibia defects treated with 3 mm passage HA/alumina scaffolds compared to without-passage HA/alumina scaffolds. It was concluded that the HA/alumina bilayered scaffold with 3 mm passage-like medullary canal was instrumental in inducing host-scaffold engraftment of the defect as well as distributing the newly formed bone throughout the scaffold at 8 weeks after implantation.

Tensile Strength of GFRP Reinforcing Bars with Hollow Section

Fiber reinforced polymer (FRP) has been proposed to replace steel as a reinforcing bar (rebar) due to its high tensile strength and noncorrosive material properties. One obstacle in using FRP rebars is high price. Generally FRP is more expensive than conventional steel rebar. There are mainly two ways to reduce the cost. For example, one is making the price of each composition cost of FRP rebar (e.g., fibers, resin, etc.) lower than steel rebar. Another is making an optimized design for cross section and reducing the material cost. The former approach is not easy because the steel price is very low in comparison with component materials of FRP. For the latter approach, the cost could be cut down by reducing the material cost. Therefore, an idea of making hollow section over the cross section of FRP rebar was proposed in this study by optimizing the cross section design with acceptable tensile performance in comparison with steel rebar. In this study, glass reinforced polymer (GFRP) rebars with hollow section and 19 mm of outer diameter were manufactured and tested to evaluate the tensile performance in accordance with the hollowness ratio. From the test results, it was observed that the tensile strength decreased almost linearly with increase of hollowness ratio and the elastic modulus decreased nonlinearly.

Structural Health Monitoring in Cylindrical Structures Using Helical Guided Wave Propagation

Defect detection and characterization are critical tasks for structural health monitoring of pipe-like engineering structures. Propagation and detection of ultrasonic helical Lamb waves using macro fiber composite (MFC) sensors is studied. Experiments for defect detection and characterization on an aluminum hollow cylinder (114mm in outer-diameter and 6mm of wall thickness) were carried out. An experimental setup using MFC sensors coupled to the cylinder's surface in a pitch-catch configuration is presented. Time-frequency representation (TFR) using wavelets is employed to accurately perform mode identification of the ultrasonic captured signals. The initial results indicate that the use of helical waves could allow the monitoring of damage in difficult to access critical areas by locating the sensors only on a small region of the periphery of the cylindrical structure under inspection.

The influence of axial compressive stresses on the formability and scattering of process parameters in micro-hydroforming processes of tubes

Feasible product geometries manufactured with micro-hydroforming, as well as process stability are crucially influenced by the microstructure of the used tube material. The higher ratio of grain size to tube wall thickness d k / t 0 in micro-hydroforming, compared to conventional tube hydroforming, leads to an increase of scattering of process parameters and instabilities. This paper presents experimental and theoretical results for the micro-hydroforming of tubes made from stainless steel and from platinum with a focus on the correlations between the microstructure of the workpiece material, the stress state during forming and the resulting stability of the forming process. Investigated tube dimensions were 800 µm outer diameter and 40 µm wall thickness of the steel tubes, respectively 1650 µm and 76 µm of the platinum tubes. The average ratio d k / t 0 was about 0.3 for the steel material and about 0.9 for the platinum alloy. It has been shown that superimposed axial stresses are suitable to reduce the restricting influence of an increased ratio d k / t 0 and to improve the forming result as well as the process stability.

Mid-term clinical results of total hip arthroplasty using a Wagner standard cup for dysplastic hip

BackgroundThe outcome of cementless total hip arthroplasty depends on many factors. We must not forget fundamental things those are design of outer surface of the component, that leads bone ingrowth into the prosthesis, better initial stability, and better insertional techniques. The purpose of this study was to review our experience with metal-on-metal total hip arthroplasty with a Wagner standard cup for patients who had acetabular dysplasia. Patients and methodsFifty-four patients with 55 hips underwent primary metal-on-metal total hip arthroplasty (Metasul prosthesis) with a Wagner standard cup (44–48 mm in outer diameter) and were followed for a minimum of 10 years. All patients received the same type of cementless femoral component (Natural hip stem) and femoral head (28 mm in diameter). ResultsSeventeen of the 55 Wagner standard cups (30.9%) showed aseptic loosening over a mean period of 3.6 years after surgery, and there were no bone anchors on the outer surface of the 16 retrieved cups. ConclusionFrom our experience, the small Wagner standard cup does not achieve sufficient osteointegration and we do not recommend the use of this cup, especially for patients with acetabular dysplasia and/or those with a small stature.