Nylon Balls Research Articles

Novel CAD–CAM fabrication of a custom-made ball attachment retentive housing: an in-vitro study

PurposeThis study aims to evaluate the digitally designed ball attachment housing in its initial retentive force and after 2 years of simulated clinical use and to compare it with the regular nylon ball attachment housing.Materials and methodsTwenty implants with their corresponding ball abutments (diameter 4.5 × 4.0 mm) were inserted in resin blocks. They were divided into two groups. In Group I, ten ball abutments each received their corresponding conventional attachment with nylon rings. In Group II, ten ball abutments received the novel CAD–CAM polyetheretherketone ball attachment housing. A universal testing machine was used to measure the retention force. The achieved maximum values of retention force were recorded at the beginning of the study (initial retention) and after 2 years of artificial ageing (2000 cycles of insertion and removal). Results were statistically analyzed using an independent sample T test.ResultsThe PEEK attachment housing showed high retention forces (25.12 ± 0.99 N) compared to the conventional attachment with a nylon ring (15.76 ± 0.93 N) in the initial dislodgement test. There was a statistically significant difference in mean retention at the initial retention test and after 2 years of stimulated usage between the two studied groups, p = 0.000.ConclusionsWithin the limitations of this study, the novel CAD–CAM–PEEK attachment showed high retention characteristics compared to the conventional attachment with nylon rings, initially and after simulated long-term use.

Development of large size crystal growth technology of oxide eutectic scintillator and a proto-type Talbot–Lau imaging system

Wafers of Tb-doped GdAlO3/α-Al2O3 eutectic were fabricated by the micro-pulling-down method using an Ir crucible with a 25 × 25 mm2 die. A prototype X-ray phase imaging detector was developed using a CMOS sensor with a fiber optic plate and the eutectic wafer. X-ray spots with an 8.24 μm period were observed using the detector. X-ray phase imaging of a nylon ball with a diameter of 4 mm was also carried out. It was observed that a phase change of approximately 2 μm occurs at the air–nylon interface. This technique of X-ray phase imaging can be realized in the absence of an absorption grating.

A Permanent Common Carotid Filter for Stroke Prevention in Atrial Fibrillation: Ex Vivo and In Vivo Pre-Clinical Testing

Background and purposeA novel, permanent, bilateral, common carotid artery (CCA) coil filter implant was designed to capture stroke-producing emboli in atrial fibrillation patients. Under ultrasound guidance, it is automatically deployed through a 24-guage needle and is retrievable up to 4 h post-procedure. We assessed the feasibility, safety, and effectiveness of the CCA filter in pre-clinical testing. MethodsIn a pulsatile flow simulator, the filter's embolic capture efficiency and integrity of simulated (1.2 mm diameter nylon balls) and actual thromboemboli were tested. Implant insertion, retrieval, and chronic safety were tested in sheep by ultrasound and X-ray. At termination, the CCAs were explanted and examined by pathology, histopathology and scanning electron microscopy. The fate of captured emboli was evaluated in sheep 3 weeks after upstream injection of autologous thromboemboli. ResultsIn the flow simulator, 10 filters captured 29 of 29 (100%) 1.2 mm diameter nylon balls. In the thromboemboli integrity test, all captured thromboemboli (99 of 99) were adherent to the filter, without fragmentation. All sheep (n = 30/60 implants) underwent successful CCA filter implantation. During follow-ups at 4, 12, 13, 23, and 31 weeks (6 sheep/12 implants at each follow-up), there were no (0%) major bleeds, CCA damage/stenosis, implant migration, flow obstruction, or thrombi detected by ultrasound. Two organized microthrombi (<100 μm) were observed by histopathology at the puncture site. After 3 weeks, autologous captured thromboemboli (n = 10) either completely regressed (5 of 5) or did not progress (5 of 5). ConclusionThese favorable pre-clinical results prompt clinical testing of the CCA filter in stroke prevention clinical trials.

The effect of shape and size distribution of abrasive particles on the volume loss of enamel using micro-abrasion

Wear of enamel during tooth brushing is a complex phenomenon with many variables affecting the level of loss. Toothpastes contain angular abrasive particles at a concentration of 12%–15% v/v abrasive designed to remove biofilm and extrinsic stains that also have the potential to harm the tooth enamel resulting in wear. Toothpastes contain multi-modal particles in the size range of 4μm–12μm. The aim of this paper is to develop an understanding of the relationship between the combined effects of particle shape, size, size distribution and load on the volume loss of enamel under abrasive testing. Micro-abrasion testing using a Nylon ball, to simulate the toothbrush, was undertaken on hydrated bovine enamel disks using volume concentrations of 5% – 20% v/v alumina and silica. Post experimental surface analysis was performed to analyse the wear scar morphology and groove analysis. The synergistic effects were calculated of bimodal particles vs. mono sized particles. Mono-sized particles as compared to bimodal, appeared to give the best outcome and least wear of enamel. A positive synergy existed for the alumina and silica bimodal tests, indicating the bimodal particle distribution was causing more wear than the mono-sized particles. The mechanism of material removal was a combination of crushing and fracture of the enamel prisms (rods), followed by micro-chipping and removal of enamel. The magnitude and the distribution of the particle sizes is the most dominant factor in determining the levels of wear, with smaller particles and narrow distributions of the particle size reducing the magnitude of wear. The shape of the particles is also a major factor influencing wear, with the spherical tests generating lower wear rates than the angular tests.

Volume fracturing Of Temporary plugging Agent for Oil Well

There are many classification methods for temporary plugging volume fracturing. According to different temporary plugging positions and temporary plugging targets, temporary plugging volume fracturing technology can be divided into temporary plugging in fractures and temporary plugging between fractures. According to the number of temporary plugging, it can be divided into one temporary plugging and multi-level temporary plugging. According to the action mode of temporary plugging, it can be divided into physical temporary plugging and chemical temporary plugging. According to the type of temporary plugging agent, it can be divided into plugging balls (plastic balls, rubber balls, nylon balls, wax balls) temporary plugging, fiber temporary plugging, large particle size proppant temporary plugging, etc. In Changqing, Daqing and Xinjiang oilfields in China, temporary plugging agents have been reported to be used for in-fracture diversion fracturing to improve reservoir productivity, and certain effects have been achieved. Compared with conventional staged fracturing, the temporary plugging of the seam to fracturing technology has the following advantages: conventional staged fracturing is difficult to implement, the temporary plugging of the seam to fracturing technology can be used to realize effective layering (segment) reconstruction, general fracturing reconstruction is insufficient, and temporary plugging of the seam to fracturing can be used to improve thereconstruction effect.

オオミジンコによる水中物体搬送作業の検討

We have been investigating how to use behavior controlled Daphnia as a living micromachine The Daphnia's control was done by applying their phototaxes. In this study, we developed underwater operation tool for Daphnia. We installed an operational tool called 'Y-Wing custom' to the Daphnia's back and investigated the vertical object transportation performance of the tool installed Daphnia. In the beginning of the development, the attached tool disturbed Daphnia's swimming, and the object transportation performance of the Daphnia with operational tool was not improved comparing to the Daphnia without any tool. After the improvement of the tool shape, we succeeded to move and drop a nylon ball on the shelf from the designated end point of the shelf by manually controlled Daphnia in the vertical plane pool.

Tribology of Graphite-Filled Polystyrene

Self-lubricating polymer compounds are currently used for a wide range of applications such as bearings, gears, and water meters. Under severe conditions such as high pressure, high velocity, and/or high temperatures, the material fails (PV limit). In this study, we investigated the effect of graphite on the tribological properties of polystyrene (PS) with “ball-on-three-plates” tests. Graphite-filled PS plates were produced via an internal mixer and compression molding. Unhardened steel (1.4401) and nylon (PA66) balls were used for the tribological tests. Our results indicate that graphite loading, graphite type, and particle size have a big influence on the friction coefficient, the wear resistance, and the PV limit of PS both against steel and PA66. In particular, primary synthetic graphite performs better than secondary synthetic graphite due to the higher degree of crystallinity.

Novel intermittent solid slug feeder for fast pyrolysis reactors: Fundamentals and modeling

To prevent plugging and help the raw biomass particles effectively penetrate and spread into the pyrolysis fluidized beds, one could inject the particles using intermittent slugs created by propelling loosely packed particles with gas pulses and transporting them along horizontal or inclined feeding pipes into the fluidized bed section of the reactor; this would combine the advantages of the low gas consumption of the screw feeders and the short residence time in high temperature zones of dilute phase feeders.Dried distillers' grain (DDG) and meat and bone meal residues (MBM) were selected as model feedstocks for experimental testing and modeling of a novel intermittent solid slug feeder technology. These feedstocks were chosen as much work has been done to attempt to process them into value-added products via fast pyrolysis, but they also possess very challenging flow characteristics and properties that are very different from each other (particle size, cohesivity, temperature sensitivity, density). As a result, creating a predictive model that can successfully model these challenging feedstocks is the basis to model any biomass of interest.The biomass flow in the feeding tube begins as an induced dense-phase flow and develops into a high velocity ‘aerated bed flow’. Gas leakage, solid friction and force-momentum balances were considered in the model. The model was developed from experimental data collected with simplified plugs (modified nylon ball), as well as real biomass slug flow.Several important variables were identified. They included the material flow properties, the gas capacitance pulse pressure and volume, and the length and material of feeding tube. The goals of this study were to (a) characterize the fundamental dynamic behavior of the biomass slugs in the feeder, (b) maximize the solid-to-gas feeding ratio, and thus minimize energy consumption, (c) minimize the accumulation of “straggler” biomass material in the feeding tube between pulses, and thus preventing biomass pre-cooking in the feeding tube and plugging (d) develop and validate a predictive model for the slug velocity at any point in the feeding tube (and thus the maximum feeding tube length), that can be applied for feeder and reactor design for any biomass feedstock, and (e) identify future areas of work for the ICFAR intermittent solid feeder.

Effects of Rotational Stirring on Zn-0.05%Sn Alloy Castings

Tin is effective for reducing the grain size of pure zinc castings, but on the contrary causes intergranular corrosion of the castings when more than 0.05 % is added. The cast structure of Zn-0,05 % Sn alloy solidified in stirring was investigated. To observe the effects of stirring on the movement of liquid, a solution of water and 60 % glycerin with 66 nylon balls were stirred in an acryl vessel at various conditions. The results obtained are as follows. Granular crystals that had separated accumulated at the bottom of vessel when the effects of stirring on the water or solution were not observed at the bottom of vessel. But columnar crystals were seen to develop from the bottom of vessel when they were indicating, stirring at 2∼3 s -1 was effective for reducing grain size.

Effects Of Exercise On Appetite And Whole Saliva in Humans

We previously confirmed that the sight and smell of food enhance appetite and salivary flow, and decrease salivary viscosity. PURPOSE AND METHODS: To examine the effect of exercise on appetite and the characteristics of saliva, six subjects performed high-intensity exercise for 12 min [2.0 and 1.6 W/kg (weight) for males and females, respectively] and low-intensity exercise for 24 min [1.0 and 0.8 W/kg (weight) for males and females, respectively] after a 3-min baseline. Then subjects rested for 36 min as a recovery phase. Whole saliva was collected for 3 min at the baseline and every 12 min during exercise and recovery phase. Subjects rated prospective food consumption on a 100-mm visual analog scale (Question: How much food do you think you could eat? Answer: 0 = nothing at all, 100 = a large amount). Subjects placed a nylon ball (15 mm in diameter) in their oral cavity to promote salivary flow. We then measured the flow and viscosity of saliva. RESULTS: The rate of prospective food consumption increased 30 min after the end of low-intensity exercise (p < 0.05), but did not change during and after high-intensity exercise. Compared to the resting baseline, salivary flow significantly decreased during high-intensity exercise, but not during and after low-intensity exercise. The viscosity of saliva did not significantly change in response to exercise. There was no significant correlation between the changes in appetite and saliva variables. CONCLUSION: These results suggest that the effects of exercise on appetite and salivary flow depend on the intensity of the exercise, and that the change in appetite associated with exercise does not relate to the characteristics of saliva. Supported by a grant from the Asahi Brewries Foundation awarded to NH.

Preparation of Micrometer‐ to Sub‐micrometer‐Sized Nanostructured Silica Particles Using High‐Energy Ball Milling

Nanostructured porous silica particles with sizes in the micrometer to sub‐micrometer range are of great interest due to their potential applications as catalyst supports and nanocomposite materials. However, if these particles are to be used in industry, a process must be developed to affordably produce them on a large scale. This paper reports on a high‐energy ball‐milling process that has been used to create micrometer‐ to sub‐micrometer‐sized mesoporous silica particles starting from a silica xerogel prepared by a surfactant self‐assembly sol–gel process. We have studied various milling conditions such as milling media (zirconia, stainless steel, or steel‐centered nylon balls), milling time, and the presence of surfactants during milling and the resulting effect on particle size and pore structure. Results from transmission electron microscopy, scanning electron microscopy, X‐ray diffraction, light scattering, and nitrogen adsorption demonstrate the feasibility of producing large quantities of nanostructured particles by this simple milling process.

Characterization of small nodules by automatic segmentation of X-ray computed tomography images.

To characterize the ability of an automatic lung nodule segmentation algorithm to measure small nodule dimensions and growth rates. A phantom of 20 sets of 6 balls each (11 different nylon balls and 9 acrylic balls) of 1 to 9.5 mm in diameter, in foam, was imaged using x-ray computed tomography with slice thicknesses of 5, 2.5, and 1.25 mm, pitches of 3 and 6, and standard and lung resolution. Measurements consisted of volume and maximum in-plane cross-sectional areas and their derived maximum and effective diameters. Growth rates were simulated using pairs of groups of balls. Volume measurements overestimate volume, more so for thicker slices. For the largest balls, the error is 60% for 5-mm slices and 20% for 1.25-mm slices. Effective diameter calculated from volume better approximates actual diameter. For area measurements, errors are 0% to 5% for the largest balls, and the effective and actual diameters are closely matched. Below 5 mm in diameter, changes in volume should reach 100% for reliable indication of growth. Above 6 mm, the threshold for detecting change is on the order of 25% growth. Even under ideal conditions, results indicate the need for caution when making a diagnosis of malignancy on the basis of volume change.

Micron to Sub-Micron Sized Highly Ordered Mesoporous Silica Particles Prepared Using a High Energy Ball Milling Process

AbstractHighly ordered mesoporous silica particles with sizes in the micron to sub-micron range are of great interest due to their applications as catalysts and filler materials. Currently, mesoporous silica particles are synthesized using large amounts of solvent, which is impractical for large scale-up in industry. This paper reports on a high-energy ball milling process that has been employed to create micron to sub-micron sized mesoporous silica particles starting from a silica xerogel prepared by a surfactant self-assembly sol-gel process. We have studied the effect of parameters such as milling media (e.g., zirconia, stainless steel, and steel centered nylon balls), milling time, the presence of surfactants during milling, particle size, and pore structure. Results from transmission electron microscopy (TEM), scanning electron microscopy (SEM), Xray diffraction (XRD), and nitrogen adsorption demonstrate the feasibility of producing large quantities of mesostructured particles by a simple milling process.

143 雨滴によるGFRP衝撃の損傷機構に関する研究(OS5-2 異物衝突損傷)(OS5 材料の衝撃強度・損傷に関する最近の知見)

When being subjected to high speed-low density particle impact such as a raindrop impact against the FRP aircraft in flight, FRP may be damaged. To evaluate the integrity of the structures, the damage mechanism caused by such impact must be clarified. GFRP disks of 100 mm in diameter were exposed to repeated impact of nylon balls in the experiments. Observation of the disk specimens during and after the experiments revealed that a white zone caused by nylon ball collision spread through the disk thickness. Sectioning of the disk specimen enables to observe the de-lamination between the second and the third layer. The close observation of the white zone indicated that the damage inside the zone consists of micro-cracking, and de-bonding of the fibers and the matrix To understand mechanisms of the observed damage modes, dynamic stress analysis was carried out by ANSYS FEM code. The analytical results indicated that shear stress component plays a dominant role to cause the white zone damage.

Colloidal filtration of silicon nitride aqueous slips. Part I: optimization of the slip parameters

The slip parameters for the manufacture of dense, pressureless sintered silicon nitride by colloidal forming methods, such as slip or pressure casting, are studied. This work focuses the optimization of the rheological behaviour of the slip considering different kinds and concentrations of dispersants and it has been stated that the electrostatic stabilizing mechanism is essential. The best rheological conditions are achieved with tetramethylammonium hydroxide (TMAH) or any strong base (as NaOH), but the use of TMAH limits the progressive oxidation of the particles suspended in water by action of a partially oxidized protective screen. The study has been made with Al 2O 3 and Y 2O 3 as sintering aids, in concentrations of 3 and 6 wt% each. An optimum pH for dispersing has been located at 11·3±0·2, where neither yield point nor thixotropy are found for 65 wt% slips. Different homogenizing techniques are used and compared, such as strong mechanical agitation, centrifugal milling or mixing in a rotatory bottle with nylon balls. Since the starting silicon nitride powder is submicronic, no milling is required, but a long homogenization time is convenient to assure an equilibrium state at the particles surface.

Function of upper esophageal sphincter during swallowing: the grabbing effect.

This study investigated deglutitive axial force developed within the pharynx, upper esophageal sphincter (UES), and cervical esophagus. Position and deglutitive excursion of the UES were determined using combined manometry and videofluoroscopy in eight healthy volunteers. Deglutitive clearing force was quantified with a force transducer to which nylon balls of 6- or 8-mm diameter were tethered and positioned within the oropharynx, hypopharynx, UES, and cervical esophagus. Axial force recordings were synchronized with videofluoroscopic imaging. Clearing force was dependent on both sphere diameter (P < 0.05) and location, with greater force exhibited in the hypopharynx and UES compared with the oropharynx and esophagus (P < 0.05). Within the UES, the onset of traction force coincided with passage of the pharyngeal clearing wave but persisted well beyond this. On videofluoroscopy, the persistent force was associated with the aboral motion of the ball caught within the UES. Force abated with gradual slippage of the UES around the ball. The force attributable to the combination of UES contraction and laryngeal descent was named the grabbing effect. The grabbing effect functions to transfer luminal contents distal to the laryngeal inlet at the end of the pharyngeal swallow, presumably acting to prevent regurgitation and/or aspiration of swallowed material.

Surface damage of polymethylmethacrylate plates by ice and nylon ball impacts

A study is described of the impact process and the corresponding surface damage to PMMA (polymethylmethacrylate) targets impacted by ice and nylon spheres. A gas gun system was used to project the spheres and the impacts were recorded using a high-speed image converter camera (Imacon 792). Special attention was paid to the conditions causing projectile failure and the surface damage to the target. The experimental results show that although the deformation and failure modes for ice and nylon are different, the surface damage to the PMMA target has a similar failure pattern, i.e., a central, circular undamaged region surrounded by an annular damaged region containing many short circumferential cracks. Analysis shows that the diameter d of the central undamaged region and the annular damaged area Am can be used to characterize the surface damage which depends on the projectile material, sphere radius R, as well as the impact velocity V0. For a given projectile, two critical impact velocities exist: One is the threshold velocity (V0)th, below which no visible surface damage is observed, and another is the fracture velocity (V0)f, above which a plate target is broken. Damage in the annular region is caused by the Rayleigh surface wave in the present experiments. The conditions for the Rayleigh surface wave to pass ahead of the expanding edge contact velocity are analyzed. Comparisons between the theoretical predictions and experimental results, including the present study and earlier data, are made for PMMA plates impacted by projectiles of different materials (ice, nylon spheres, and water drops) and at different impact angles.

Improved wear properties of high energy ion-implanted polycarbonate

Polycarbonate (LexanTM) (PC) was implanted with 2 MeV B+ and O+ ions separately to fluences of 5 × 1017, 1 × 1018, and 5 × 1018 ions/m2, and characterized for changes in surface hardness and tribological properties. Results of tests showed that hardness values of all implanted specimens increased over those of the unirradiated material, and the O+ implantation was more effective in improving hardness for a given fluence than the B+ implantation. Reciprocating sliding wear tests using a nylon ball counterface yielded significant improvements for all implanted specimens except for the 5 × 1017 ions/m2 B+-implanted PC. Wear tests conducted with a 52100 steel ball yielded significant improvements for the highest fluence of 5 × 1018 ions/m2 for both ions, but not for the two lower fluences. The improvements in properties were related to Linear Energy Transfer (LET) mechanisms, where it was shown that the O+ implantation caused greater ionization, thereby greater cross-linking at the surface corresponding to much better improvements in properties. The results were also compared with a previous study on PC using 200 keV B+ ions. The present study indicates that high energy ion irradiation produces thicker, more cross-linked, harder, and more wear-resistant surfaces on polymers and thereby improves properties to a greater extent and more efficiently than lower energy ion implantation.

Wear properties of argon implanted poly(ether ether ketone)

The sliding wear properties of Ar +-implanted poly(ether ether ketone) (PEEK) using nylon 66 and SAE 52100 high carbon chrome steel ball counterfaces have been investigated in this study. PEEK was implanted with 1 MeV Ar + to fluences of 5 × 10 18, 1 × 10 19 and 5 × 10 19 ions m −2. Reciprocating sliding wear tests were conducted using a 1 N normal load, 3 mm sliding distance and 100 cpm frequency for 10 000 sliding cycles. The implantation significantly improved the wear properties of PEEK for the nylon ball tests to the extent that no wear tracks were evident on the PEEK surface. This was attributed to significant strengthening of the PEEK surface by ion beam induced cross-linking which, in turn, caused corresponding wear of the softer nylon counterface. For the steel counterface tests, the intermediate-fluence implanted specimen showed no wear damage on the surface. There was wear damage for the unimplanted, lower and higher fluence implanted specimens. The results indicate that the best wear properties appeared at some optimum level of ion-beam induced cross-linking of PEEK for the steel counterface. Friction coefficient data were correlated with the observed wear behavior. Mechanisms of energy transfer from the energetic ions to the polymer molecules were analyzed to explain the wear improvements. This study shows that ion implantation is a promising technique for significant improvements in the tribological properties of PEEK.

Immobilized enzyme catalyzed removal of 4-chlorophenol from aqueous solution

The ability of horseradish peroxidase enzyme attached on three different reactor matrices: cellulose filter paper, nylon balls and nylon tubing, to remove 4-chlorophenol from aqueous solution is evaluated. The enzymatic reaction is extremely fast and the reaction products remained on the reactor matrix. Detachment or release of the reaction products from the reactor matrix is not observed. Results indicate that, over 80% removal efficiency can be obtained as long as enzyme activity is not limiting in the reactor. Systematic recycle batch reactor studies reveal that, initial reaction rates exhibit saturation with substrate concentration under conditions of excess peroxide. Inactivation of enzyme active sites by reaction intermediates is observed in the reactor studies. Immobilized peroxidase also catalyzes the oxidation of other chlorophenols and cresols.