Viscosity Of Silicone Oil Research Articles

The changes in physical properties of silicone oil after intraocular tamponade

Objective To observe the changes in physical properties of silicone oil after intraocular tamponade. Methods The silicone oil was removed from 99 patients (99 eyes) of primary retinal detachment with 23G vitreous cutter system. The upper silicone oil was collected after put the vitrectomy samples at room temperature for 3 days. According to the time of intraocular tamponade, the silicone oil samples were divide into six groups including group A (1 month, 12 samples), group B (2 months, 15 samples), group C (3 months, 25 samples), group D (6 months, 22 samples), group E (1 - 2 years, 13 samples) and group F (above 2 years, 12 sample). Fresh unused silicone oil was set as blank control group. Then the emulsion particles, kinematic viscosity, surface tension, density, transmittance and refractive index were measured. Results The difference between group A - F and the control was statistical significant (P 0.05). The number of silicone oil emulsion particles has no statistical difference between group A and the control (P>0.05), but was significantly different between group B - F (P 0.05), but was significantly different between group C - F (P 0.05), but is significantly different between group E and F (P 0.05), but was significantly different between group E and F (P 0.05). Conclusions The physical properties of silicone oil will change during the intraocular tamponade. The emulsion particles number will increase and the transmittance will decrease after 2 months, the kinematic viscosity of silicone oil will decrease significantly after 3 months, and the density and surface tension will change significantly after 1 year of tamponade. Key words: Silicone oils/therapeutic use; Silicone oils/ adverse effects

Analysis of Action Viscous Torsional Vibration Damper of the Crankshaft Based on Transverse Vibration the Engine Block

The article presents an example of research results of the mechanical vibrations of the internal combustion engine with a viscous torsional vibration damper of the crankshaft for different values of the viscosity of silicone oil. A comparison of the crankshaft torsional vibration and the transverse vibration motor body was made. There was proposed the use of the information contained in the transverse vibration signals in order to determine the changes in the technical condition of the viscous damper (changes in viscosity of silicone oil fillingthe damper). Accepting the argument which assumes that there exists the coupling vibration and torsional shaft bent in transverse vibration signals, there should appear symptoms associated with changes in the torsional vibrations. In order to prove this thesis there was conducted active research experiment. Measurements of transients during engine acceleration were made. There was presented the example of the results of measurements of the crankshaft torsional vibrationand the transverse vibration of the motor body.

In Vitro Modeling of Emulsification of Silicone Oil as Intraocular Tamponade Using Microengineered Eye-on-a-Chip.

There is a lack of a standardized methodology or a physiologically realistic in vitro model to investigate silicone oil (SO) emulsification. In this study, we replicated the SO-aqueous interface within a microfluidic chip to study the formation of SO emulsion droplets in the eye cavity. A chip made of poly(methylmethacrylate) was used to represent a cross-section of the posterior eye chamber. A retinal ganglion cell line was coated on the inner surface of the chamber to mimic the surface property of the retina. Silicone oil of different viscosities were tested. The SO-aqueous interface was created inside the chip, which, in turn, was affixed to a stepper-motor-driven platform and subjected to simulated saccadic eye movement for four days. Optical microscopy was used to quantify the count and size of SO emulsified droplets. Among SO of different viscosities, SO 5 centistokes (cSt) emulsifies readily, and a high number of droplets formed inside the chip. Silicone oil 100 cSt led to fewer droplets than 5 cSt, but the droplet count was still significantly higher than other SO of higher viscosities. There were no significant differences in the number of droplets among SO with viscosities of 500, 1000, and 5000 cSt. In all SOs tested, the number of droplets increased, whereas their size decreased with longer duration of simulated saccades. The study platform allows quantification of the number and size of emulsified SO droplets in situ. More importantly, this platform demonstrates the potential of microtechnology for constructing a more physiologically realistic in vitro eye model. Eye-on-a-chip technology presents exciting opportunities to study emulsification and potentially other phenomena in the human eye.

Microdroplet generation using an ultrasonic torsional transducer which has a micropore with a tapered nozzle

A generation of monodisperse droplets in various liquids is an important subject. In this study, we have generated droplets by using an ultrasonic torsional transducer and the micropore plate. Firstly, we have evaluated an effect of the micropore shape to droplet generation. The diameter of the micropore and the flection angle of the tapered nozzle are \(50 \, \upmu \hbox {m}\) and \(25^{\circ }\), respectively. The micropore with a tapered nozzle prevented liquid from spreading on the micropore. Therefore, the micropore with a tapered nozzle generates liquid column. In addition, we have generated droplets in the air by using pure water and various viscosity silicone oils and evaluated the generated droplets. The uniform size droplets of various liquids were generated when the ultrasonic torsional transducer and the micropore plate vibrate in torsional direction. We have evaluated the relationship between the diameter and some values which affect droplet formation. The diameter of droplet is decided by the applied pressure, the resonance frequency and the diameter of liquid column.

Experimental investigation of electrohydrodynamic instabilities in micro channels

An electric field is applied to destabilize the interface between two Newtonian and immiscible liquids flowing in a rectangular micro channel. The liquids are pumped into the micro channel with a syringe pump and a DC electric field is applied either parallel or normal to the flat interface between these liquids. The two liquids used in the experiments are a combination of ethylene glycol, different viscosity silicone oils, castor oil, and olive oil. The onset of electrohydrodynamic instability is investigated for various parameters, including the ratios of the flow rates, and viscosities of the liquids, the width of the micro channel, and the direction of the applied electric field. The order of the voltage applied to destabilize the interface is in the range 95 and 1190 V. The results of the experiments show that an increase in the viscosity ratio and the flow rate ratio of silicone oil to ethylene glycol have a stabilizing effect. It is also found that the important parameter to determine the critical voltage is the flow rate ratio, not the individual flow rates of the liquids. Also, as the width of the micro channel increases, the critical voltage increases. Lastly, for the liquid combinations used in the experiments, the interface could not be destabilized under the influence of a parallel electric field.

Evaporation enhancement effect of TiO2 nanoparticles on silicone oil in electrorheological fluid suspension

Electrorheological (ER) fluids are suspensions which consist of dielectric particles and insulation fluid. The ER fluids can change from liquid-like to solid-like state under the applied electric field. For traditional ER fluids, the maximum yield/shear stress is only several kPa and the size of dielectric particles is generally of micron. Since 2003, a series of new type ER fluids have been discovered, of which the yield/shear stress is as high as several hundred kPa. Such a type of ER fluid is called giant ER fluid or polar molecule-dominated ER fluid (PM-ER fluid), in which the size of dispersed particles is of nanoscale. Dimethyl silicone oil is the most commonly used dispersing agent in ER fluids, because of its stable physical and chemical behaviors. There is no obvious evaporation in traditional ER fluids when it is mixed with micron grade particles. However, when it is mixed with nanoparticles to prepare giant ER fluids, the silicone oil volatilizes easily in atmosphere. If time is long enough, the silicone oil in ER suspension can even be evaporated completely. In this paper, the existence of TiO2 nanoparticles in ER suspensions enhances the volatilization phenomenon has been studied through experiment. Analysis shows that the nanoparticles caused convex nanoscale curved surfaces on the gas-solid interface makes the vapor pressure increase greatly at the silicone oil surface, and leads to the enhancement of its volatilization. Influence of particle concentration, environmental temperature and viscosity of silicone oil on the evaporation enhancement effect is also studied and analysed systematically. Results show that the increase of the fraction of nanoparticles, viscosity of silicone oil as well as the temperature would promote the effect of evaporation enhancement of silicone oil in the suspensions.

중합도에 따른 저점도 실리콘유의 유전 특성

The characteristics of dielectric constant and of low viscosity silicone oils with changing degree of polymerization were investigated. The result shows dipole loss mechanism at low temperature range. The dielectric loss in the range of low frequencies are predominantly of ionic nature with temperature increase. The peak of dielectric loss is the detrapping of the electrons which is were trapped in the localized level of the silicone oils at the frequency of 30 kHz. The increase of ionic conduction is attributed to the presence of ionizable oxidation products and their increased dissociation feature. The activation energy and dipole moment were increased whit increasing degree of polymerization.

Surgical outcomes and incidence of retinal redetachment in cases with complicated retinal detachment after silicone oil removal: univariate and multiple risk factors analysis.

To analyze the surgical outcomes and retinal redetachment frequency after silicone oil (SO) removal for complex retinal detachment. This institutional-based study included 894 consecutive patients who underwent pars plana vitrectomy with SO endotamponade for complicated retinal detachment. The effects of preoperative best-corrected visual acuity, vitreous base shaving, intraoperative scleral buckling, retinectomy, SO viscosity, duration of SO, and vitreous hemorrhage at the first postoperative week on the risk of redetachment were investigated. During a mean follow-up of 39.9 months, anatomical success was not achieved in 118 patients (13.2%) after SO removal. On multivariate analysis, risk factors for recurrent retinal detachment included giant retinal tear (adjusted odds ratio [aOR], 12.39; P < 0.001), high myopia (aOR, 2.70; P = 0.011), surgeries without scleral buckling (aOR, 1.97; P = 0.039), inadequate vitreous base shaving (aOR, 117.62; P < 0.001), and vitreous hemorrhage at the first postoperative week (aOR, 12.13; P < 0.001). Retinal detachment etiology, inadequate vitreous base shaving, lack of intraoperative scleral buckling, and vitreous hemorrhage at the first postoperative week after SO removal were significant risk factors for retinal redetachment after SO removal, but preoperative visual acuity, SO viscosity, and duration of SO had no significant effect on redetachment.

Onset of Marangoni convection in low viscosity silicon oil inside a heated capillary tube

In the present experimental investigation the onset of Marangoni convection inside a heated capillary tube filled with low viscosity silicon oil is presented and discussed. The 1 cSt viscosity silicon oil used evaporates spontaneously at ambient temperature. The evaporation of silicon oil inside the 1 mm internal diameter tube is not uniform, being larger near the meniscus triple line region than in the centre; this creates gradients of temperatures (which have been measured by InfraRed thermography) and therefore of surface tension. For the unheated tubes this gradient of surface tension is found to be not big enough to set a convection motion (Marangoni convection) which was reported by one of the present authors in previous studies using alcohols. With increasing power supplied to the tube by an electric heater, the Marangoni convection sets in and strengthens at increasing powers till the pinned meniscus detaches from the tube mouth and recedes inside the capillary.

Preparation of spherical and cubic Fe55Co45 microstructures for studying the role of particle morphology in magnetorheological suspensions

Cubic and spherical Fe55Co45 alloyed microstructures were synthesized by borohydride reduction from aqueous solutions of metallic precursors, using stabilizers and polymer. Monosodium citrate, sodium acetate and PEG 6000 were utilized as electrostatic stabilizers and polymeric surface modifier. Suitable reaction conditions were maintained for synthesis of predominantly larger particles (0.7µm to 1.2µm), that facilitates use in magnetorheological fluids. Surface morphological studies by scanning electron microscopy revealed well shaped cubic and spherical geometry for the citrate and polymer-stabilized Fe55Co45 alloys, while the alloy compositions remained nearly the same for both. X-ray diffractions of the as-prepared and annealed samples under various temperatures showed high degree of crystallinity with increasing temperatures. Studies of D.C. magnetization of the systems reveal that the particles have a core–shell structure, with inner magnetic core having a diameter around 30nm with a log-normal distribution. Magnetorheological studies were performed with 8vol% suspensions of as-synthesized particles dispersed in silicone oil (viscosity 30mPas at 25°C) under different magnetic fields. Detailed studies of the magnetorheological properties were studied on these systems for practical use.

Preparation and Characterization of Hyperbranched Silicone Oil by Hydrosilylation Reaction

Hyperbranched silicone oil was prepared using low-polyhydrosiloxane and vinyl terminated methylphenyl silicone oil as the raw materials through hydrosilylation reaction. The structures and properties of hyperbranched silicone oil were characterized through 1H NMR, TG and dynamic viscosity. The influence on synthesis of hyperbranched silicone oil was discussed, which was caused by ratio of different raw materials. When molar ratio of Si-H bond and Si-Vi bond of raw materials was 3.5:1 (mol), the reaction degree of hyperbranched silicone oils double bond was as high as 80%. At room temperature and 100°C, comparing the dynamic viscosity of hyperbranched silicone oil and straight chain silicone oil, we found that viscosity decrease rate of hyperbranched silicone oil was obviously lower. TG curve of hyperbranched silicone oil and straight chain silicone oil also certified that the hyperbranched silicone oil has higher thermal stability than the straight chain phenyl silicone oil. Therefore hyperbranched silicone oil is more suitable for the preparation of high-performance elastic clay than straight chain silicone oil.

A study on the magneto-assisted spiral polishing on the inner wall of the bore with magnetic hot melt adhesive particles (MHMA particles)

The spiral polishing mechanism employed a fast turning screw rod to drive the abrasive for workpiece surface polishing. In this study, the powerful ring magnet installed around the workpiece would attract the self-developed magnetic hot melt adhesive particles (MHMA particles) during the process of polishing, driving the SiC particles against the workpiece, the inner wall of the bore. At the same time, the flexibility of MHMA particles helped improve the surface quality of the bore by preventing the SiC particles from heavily scratching it. The effects of magnetic flux density, size and concentration of SiC particles, concentration of MHMA particles, viscosity of silicone oil, revolution speed of the spindle as well as machining time and machining gap on operation temperature, slurry viscosity, surface roughness, and material removal were discussed and the best parameter combination was identified based on the results of the experiment. The effects of each machining parameter on the finished surface topography of the workpiece were also examined. Both analysis of variance and F-test indicated that magnetic flux density and the concentration of MHMA particles were the two most important variables affecting the surface roughness. In other words, magnetic force helped improve spiral polishing. Furthermore, the results showed that adding new MHMA particles to the slurry greatly improved the surface quality, at a rate of 90 %, and reduced the workpiece surface roughness from 0.9 μm down to 0.094 μm.

Reptation Aggregation of Liquid Silicon Oils Modified by Ar Plasmas

The aggregation behavior of silicone oil polymers exposed to Ar plasmas was investigated. A reptation aggregation related to the viscosity of silicone oil was found. The viscosity dependence η ∼ Lb on the reptation length L with b = 3.37 in the viscous coefficient range of 20 and 500 mm2 · s−1 was obtained. The formation of reptation aggregation is thought to relate to the gradient viscosity in the vertical direction due to crosslinking and formation of SiO network at the surfaces of silicone oils induced by energetic ions bombardment and the vacuum‐ultraviolet irradiation, as well as the temperature gradient in vertical direction induced by energetic ions bombardment.

Erratum to: Conductive Hearing Loss Induced by Experimental Middle-Ear Effusion in a Chinchilla Model Reveals Impaired Tympanic Membrane-Coupled Ossicular Chain Movement

Otitis media with effusion (OME) occurs when fluid collects in the middle-ear space behind the tympanic membrane (TM). As a result of this effusion, sounds can become attenuated by as much as 30-40 dB, causing a conductive hearing loss (CHL). However, the exact mechanical cause of the hearing loss remains unclear. Possible causes can include altered compliance of the TM, inefficient movement of the ossicular chain, decreased compliance of the oval window-stapes footplate complex, or altered input to the oval and round window due to conduction of sound energy through middle-ear fluid. Here, we studied the contribution of TM motion and umbo velocity to a CHL caused by middle-ear effusion. Using the chinchilla as an animal model, umbo velocity (V U) and cochlear microphonic (CM) responses were measured simultaneously using sinusoidal tone pip stimuli (125 Hz-12 kHz) before and after filling the middle ear with different volumes (0.5-2.0 mL) of silicone oil (viscosity, 3.5 Poise). Concurrent increases in CM thresholds and decreases in umbo velocity were noted after the middle ear was filled with 1.0 mL or more of fluid. Across animals, completely filling the middle ear with fluid caused 20-40-dB increases in CM thresholds and 15-35-dB attenuations in umbo velocity. Clinic-standard 226-Hz tympanometry was insensitive to fluid-associated changes in CM thresholds until virtually the entire middle-ear cavity had been filled (approximately >1.5 mL). The changes in umbo velocity, CM thresholds, and tympanometry due to experimentally induced OME suggest CHL arises primarily as a result of impaired TM mobility and TM-coupled umbo motion plus additional mechanisms within the middle ear.

Conductive Hearing Loss Induced by Experimental Middle-Ear Effusion in a Chinchilla Model Reveals Impaired Tympanic Membrane-Coupled Ossicular Chain Movement

Otitis media with effusion (OME) occurs when fluid collects in the middle-ear space behind the tympanic membrane (TM). As a result of this effusion, sounds can become attenuated by as much as 30-40dB, causing a conductive hearing loss (CHL). However, the exact mechanical cause of the hearing loss remains unclear. Possible causes can include altered compliance of the TM, inefficient movement of the ossicular chain, decreased compliance of the oval window-stapes footplate complex, or altered input to the oval and round window due to conduction of sound energy through middle-ear fluid. Here, we studied the contribution of TM motion and umbo velocity to a CHL caused by middle-ear effusion. Using the chinchilla as an animal model, umbo velocity (V U) and cochlear microphonic (CM) responses were measured simultaneously using sinusoidal tone pip stimuli (125Hz-12kHz) before and after filling the middle ear with different volumes (0.5-2.0mL) of silicone oil (viscosity, 3.5 Poise). Concurrent increases in CM thresholds and decreases in umbo velocity were noted after the middle ear was filled with 1.0mL or more of fluid. Across animals, completely filling the middle ear with fluid caused 20-40-dB increases in CM thresholds and 15-35-dB attenuations in umbo velocity. Clinic-standard 226-Hz tympanometry was insensitive to fluid-associated changes in CM thresholds until virtually the entire middle-ear cavity had been filled (approximately >1.5mL). The changes in umbo velocity, CM thresholds, and tympanometry due to experimentally induced OME suggest CHL arises primarily as a result of impaired TM mobility and TM-coupled umbo motion plus additional mechanisms within the middle ear.

Enhanced Fluorescence, Morphological and Thermal Properties of CdSe/ZnS Quantum Dots Incorporated in Silicone Resin

Our research focused on the morphological and optical properties of core/shell cadmium selenide/zinc sulfide (CdSe/ZnS) quantum dots incorporated in silicone resin. After dispersing ligand-coated quantum dots into Dow Corning two-component silicone resins (OE6630A and OE6630B at 1:4 mixing ratio by weight), the resins were cured at 150 degrees C for 1.5 hours to produce the quantum dot-silicone resin nanocomposites. The optical, morphological and thermal properties of the quantum dot incorporated in silicone resin were investigated by ultraviolet-visible, fluorescence, atomic force microscopy, field emission scanning electron microscopy, differential scanning calorimetry and thermogravimetric analysis. When the quantum dots, originally coated with trioctylamine ligand, were transferred from a chloroform solvent to methyl phenyl silicone oil and silicone resins of high viscosity, the quantum dots showed increased turbidity and lowered fluorescence intensity. Fluorescence enhancement was investigated by using various functional ligands such as poly(1, 1-dimethyl silazane) (multi-silazane), hexamethylenediamine (diamine), cysteamine (amino-thiol), triethylsilane (reactive hydrosilane), hexamethyldisilazane, nonamethyltrisilazane, octamethylcyclotetrasilazane (reactive amines). The results showed that the reactive amines were good additive ligands for enhancing the fluorescence of CdSe/ZnS quantum dots dispersed in the silicone resins, providing 1.2-2.48 Im/W and 4.2-5.56% higher luminous efficiency and photoluminescence conversion efficiency, respectively. We speculate that these reactive amines donate electrons to the surface electron traps, thereby reducing charge recombination. In addition, quantum dots aggregate to form quantum dot clusters with a relatively homogeneously dispersed in the silicone resin matrices, showing good emission properties due to surface passivation and good colloidal stability with the addition of silazane compounds to the resin. Furthermore, the addition of silazane compounds to quantum dots-silicone resin system also shows the improved thermal stability of the as-synthesized nanocomposites.

S083023 Stratification Behavior of Two Fluids by Gravity : (2) Analysis with MPS Method

The Moving Particle Semi-implicit (MPS) method is improved to analyze the stratification behavior of highly viscous fluids. The stratifying processes of silicone oil and salt water are simulated in 2D and 3D respectively, and the time history of fluid shapes is compared with experimental results. Characteristic fluid shapes for high and low silicone oil viscosity conditions are well predicted and the results show good agreement with experiments.

Clinical presentation of a mixed 23-gauge infusion and 20-gauge pars plana technique for active silicone oil removal.

To present with a clinical case series of a mixed 23-gauge infusion and 20-gauge pars plana technique for 5,700-centipoise silicone oil removal (SOR), and to discuss its efficacy and safety. This is a retrospective, non-randomized controlled study. We performed SOR with 23-gauge infusion and 20-gauge active suction technique on 29 patients 29 eyes from April to October, 2011 (mixed group). During the surgeries, a 23-gauge sclerotomy was made for infusion and a 20-gauge sclerotomy was used for active silicone oil suction. Anterior segment optical coherence tomography (OCT) was applied for 23-gauge sclerotomy analysis 1 day post-operation. Traditional 20-gauge SOR was performed on another consecutive 29 patients 29 eyes, the control group (20G group). There were 2 eyes (6.9%) in mixed group and 5 eyes (17.2%) in 20G group which had recurrent retinal detachment after surgery. Hopytony (IOP≤6mmHg) occurred in 8 eyes (27.6%) of mixed group and in 10 eyes (34.5%) of 20G group post-operation, but all of them recovered to the normal level finally. There were no statistical significant differences. Final visual acuity was significantly increased after surgery in both groups. Anterior segment OCT images were acquired from 13 eyes of mixed group, and all of them had a proper wound apposition. But local ciliary detachment was found in 9 eyes (69%). It was hard to define the OCT image of the sclerotomies and ciliary body because of the serious conjunctival hemorrhages and chemosis in 20G group. This mixed technique is a convenient and effective way to remove high viscosity silicone oil. Compared with traditional 20-gauge SOR, it does not increase the risk of post-operative complications and has less conjunctival reactions.. Transient postoperative hypotony is common for this procedure and subclinical ciliochoroidal detachment is a probable cause.

A Study on the Inner Wall Spiral Polishing with Magnetic Force

The spiral polishing mechanism in the present experiment employed a turning screw rod to drive the SiC and the steel grits. With a powerful magnet set around the workpiece interacting with the steel grits, the SiC abrasives were driven and then achieve the surface’s polishing effects. The best parameters combination was discussed with the control of magnetic flux density, size and weight of SiC particles, weight of steel abrasives, viscosity of silicon oil, turning speed of spindle, as well as machining time and their influences on the surface roughness. The effects of each machining parameter on the appearance of workpiece surface were also studied. Based on the results of the experiment, with the increase of machining time, the fluidity of the abrasives becomes better, and thus higher quality of polishing surface could be expected after the process of precision spiral polishing. The results also showed that the best polishing surface was found when the magnet of magnetic flux density was controlled at 90mT, particle size at 12μm, 110g of SiC grams, 60 grams of polystyrene balls, silcon oil at 1000 mm2/s viscosity, and the screw revolution speed at 3500 rpm. The surface roughness was successfully improved from 0.9μm to 0.134μm.

Evaluation of generated micro droplets using micropore plates oscillated by ultrasonic torsional transducers

This paper reports on generating micro and uniform droplets in various viscosity liquids by using a micropore plate oscillated by an ultrasonic torsional transducer. When the micropore plate was not oscillated, generated droplet diameter was not stable. On the other hand, when the micropore plate was oscillated, generated droplets became small and uniform by ruffling the liquid column surface. Droplets were generated experimentally in the air by using pure water and silicone oil of various viscosities and then evaluated. We have designed the ultrasonic torsional transducer and a droplet generation device to apply a high pressure for the use of higher viscosity liquids. We have succeeded in generating droplets by using pure water when the ultrasonic torsional transducer and the micropore plate that had an 18-μm-diameter micropore were used. The average diameter of droplets was 30.0μm and the standard deviation was 0.98. We have also succeeded in generating 50-cSt silicone oil droplets by using the droplet generation device and the micropore plate that had the 50-μm-diameter micropore. The average diameter of droplets was 98.0μm and the standard deviation was 0.76.