Layer Of Silicone Oil Research Articles

Thermocapillary convection in a liquid layer with a quasi-point heat source in the substrate

By the method of tracer particles the velocity field of thermocapillary convection in a thin layer of silicone oil, excited by a quasi-point heat source in the rigid substrate, is investigated as a function of the layer thickness, the temperature of the heater, and the liquid viscosity. The vertical velocity distributions are plotted in several cross-sections at different distances from the vortex axis. A novel method of measuring the profile of the thermocapillary depression, based on mirror reflection from the free liquid surface of radiation scattered by a tracer particle, is proposed. The central segment of the profile of the thermocapillary depression is obtained for different values of the layer thickness, the liquid viscosity and the heater temperature.

Improving Hydrophobicity of Glass Surface Using Dielectric Barrier Discharge Treatment in Atmospheric Air

Non-thermal plasmas under atmospheric pressure are of great interestin industrial applications, especially in material surfacetreatment. In this paper, the treatment of a glass surface forimproving hydrophobicity using the non-thermal plasma generated bydielectric barrier discharge (DBD) at atmospheric pressure inambient air is conducted, and the surface properties of the glassbefore and after the DBD treatment are studied by using contactangle measurement, surface resistance measurement and wet flashovervoltage tests. The effects of the applied voltage and time durationof DBD on the surface modification are studied, and the optimalconditions for the treatment are obtained. It is found that a layerof hydrophobic coating is formed on the glass surface after sprayinga thin layer of silicone oil and undergoing the DBD treatment, andthe improvement of hydrophobicity depends on DBD voltage andtreating time. It seems that there exists an optimum treating timefor a certain applied voltage of DBD during the surface treatment.The test results of thermal aging and chemical aging show that thehydrophobic layer has quite stable characteristics. The interactionmechanism between the DBD plasma and the glass surface is discussed.It is concluded that CH3 and large molecule radicals can reactwith the radicals in the glass surface to replace OH, and thehydrophobicity of the glass surface is improved accordingly.

Novel coating method for artificial opal films and its process analysis

Closely packed colloidal crystals, artificial opal, have been actively studied as materials that exhibit structural colors and photonic band gap. Opal films were self-assembled with mono-dispersed submicron particles. The author proposed a novel and simple method to grow a uniform opal film comprised cubic closely packed, ccp (1 1 1) planes on a 4 in. silicon wafer without using any special equipment. The coating method enables to form colloidal crystal films on a solid substrate in an area over 70 cm 2 under silicone oil. The author observed the change of structural color of the colloidal crystal from red to green and Bragg's diffraction peaks of 603.5 nm and 565.7 nm, respectively. This result suggests that colloidal crystal was grown on the substrate under covered silicone oil layer from colloidal suspension. Non-close-packed colloidal crystal was firstly formed during crystallization. Then the distance among the colloidal particles decreased evolution of evaporating water from the non-close-packed colloidal crystal. Finally, closely packed colloidal crystal, opal, films were formed on the substrate after perfectly evaporating water among the colloidal particles. The paper proposes a mechanism of packing process of oil covering method for opal film coating.

Friction enhancement via micro-patterned wet elastomer adhesives on small intestinal surfaces

A micro-pillar-based silicone rubber adhesive coated with a thin silicone oil layer is investigated in this paper for developing friction-based clamping mechanisms for robotic endoscopic microcapsules. These adhesives are shown to enhance the frictional force between the capsule and the intestinal wall by a factor of about seven over a non-patterned flat elastomer material. In this study, tests performed on fresh samples of pig small intestine are used to optimize the diameter of the micro-pillars to maximize the frictional forces. In addition, the effects of other factors such as the oil viscosity and applied normal forces are investigated. It is demonstrated that the proposed micro-pillar pattern based elastomer adhesive exhibits a maximal frictional force when the pillar diameter is 140 µm and coated silicon oil has a very high viscosity (10 000 cSt). It is also found that the frictional force of the micro-patterned adhesive increases nonlinearly in proportion to the applied normal force. These adhesives would be used as a robust attachment material for developing robotic capsule endoscopes inside intestines with clamping capability.

Characters of surface deformation and surface wave in thermal capillary convection

In the field of fluid mechanics, free surface phenomena is one of the most important physical processes. In the present research work, the surface deformation and surface wave caused by temperature difference of sidewalls in a rectangular cavity have been investigated. The horizontal cross-section of the container is 52 mm×42 mm, and there is a silicon oil layer of height 3.5 mm in the experimental cavity. Temperature difference between the two side walls of the cavity is increased gradually, and the flow on the liquid layer will develop from stable convection to un-stable convection. An optical diagnostic system consisting of a modified Michelson interferometer and image processor has been developed for study of the surface deformation and surface wave of thermal capillary convection. The Fourier transformation method is used to interferometer fringe analysis. The quantitative results of surface deformation and surface wave have been calculated from a serial of the interference fringe patterns. The characters of surface deformation and surface wave have been obtained. They are related with temperature gradient and surface tension. Surface deformation is fluctuant with time, which shows the character of surface wave. The cycle period of the wave is 4.8 s, and the amplitudes are from 0 to 0.55 μm. The phase of the wave near the cool side of the cavity is opposite and correlative to that near the hot side. The present experiment proves that the surface wave of thermal capillary convection exists on liquid free surface, and it is wrapped in surface deformation.

In vitro investigation on the impact of Solutol HS 15 on the uptake of colchicine into rat hepatocytes

In the current investigation, the impact of the surface-active formulation ingredient Solutol HS 15 on the uptake of colchicine into freshly isolated rat hepatocytes was investigated using a centrifugal filtration technique through a silicone oil layer. Colchicine is taken up into the cells by an active transport mechanism. When conducting the experiment at 37 °C, it was found that at concentrations below its critical micellar concentration (CMC) of 0.021% (0.0003 and 0.003%, w/v), Solutol HS 15 did not impact the uptake of colchicine. By contrast, at a Solutol HS 15 concentration above its CMC (0.03%, w/v), the amount of colchicine taken up into the cells as well as its uptake velocity were significantly decreased. However, in control experiments performed at 4 °C, a temperature at which active transport processes should be significantly slowed down, Solutol HS 15 at 0.03% did not affect colchicine uptake and/or its association with the cells. The described findings might be rationalized by inhibition of colchicine transport either due to direct interaction at the transport site or due to alterations of membrane properties in the presence of Solutol HS 15 at concentrations above its CMC. Moreover, a strong molecular interaction between Solutol HS 15 and colchicine as well as an incorporation of colchicine into micelles formed by Solutol HS 15, this way resulting in a limited contact of colchicine with the cells, cannot be excluded as contributors to the observed effect.

A sensitive and robust method for quantification of intracellular short-chain coenzyme A esters

A procedure for the analysis of short-chain intracellular coenzyme A (CoA) esters and adenine nucleotide pools in microbial cells is described. The simultaneous isolation of bacterial cells from media, quenching of their metabolism, and extraction of metabolites was accomplished by centrifugation of cells through a layer of silicone oil into a denser solution of trichloroacetic acid. The acid was neutralized by extraction into Freon containing tri- n-octylamine to provide a salt-free solution of cell metabolites. After high-performance liquid chromotography separation, CoA, CoA esters, and adenine-containing nucleotides were derivatized by postcolumn reaction with bromoacetaldehyde to form the fluorescent 1, N 6-ethenoadenine adducts which were analyzed by a fluorescence detector at picomolar levels.

Highly VOC-selective hollow fiber membranes for separation by vapor permeation

A thin layer of silicone oil was immobilized in part of the micropores of the polypropylene hollow fiber substrate beneath the plasma-polymerized polydimethylsiloxane (PDMS) skin on the outer surface of the hollow fiber. Such a liquid in the hollow fiber membrane was used to study the separation properties for the following volatile organic compound (VOC)-containing systems: toluene–N 2, methanol–N 2, acetone–N 2. The observed benefits of having the thin immobilized liquid membrane (ILM) incorporated in the microporous structure were, 2–5 times more VOC-enriched permeate since the nitrogen flux was drastically reduced and the separation factor was 5–20 times increased depending on the type of the VOC and the feed gas flow rate. The stability of such a thin ILM-based hollow fibers membrane was studied over an extended period of time (six months to two years). The stable results demonstrated the potential utility of such an ILM-based hollow fiber device for VOC–N 2/air separation. A mathematical model was also developed for VOC–N 2 permeation–separation in a hollow fiber permeator having this special type of membrane containing a thin ILM. Experimental results were compared with the results obtained by numerically simulating the mathematical model of the permeator. The values of various parameters used for the simulations were experimentally determined. The VOC outlet concentrations for all VOC–N 2 systems were well anticipated by the model simulations.

Étude expérimentale des transferts de chaleur fluide-paroi induits par convection thermocapillaire : influence du nombre de Prandtl

This article concerns heat transfer due to thermocapillary convection induced by an air bubble introduced under a heated wall into a silicone oil layer. An experimental study is carried out under normal gravity conditions with direct measurements by means of a heat fluxmeter. Effects of the bubble size and the temperature gradient are systematically investigated for two values of viscosity. The nature of the thermocapillary convection state (stationary or oscillatory) is determined by shadowgraphy. Two regimes of heat transfer are made evident. They depend on the Prandtl number but are independent of the state of the flow. To cite this article: C. Reynard et al., C. R. Mecanique 331 (2003).

Determination of ferrichrome binding to the FhuA outer membrane transport protein, periplasmic accumulation of ferrichrome, or transport of ferrichrome into cells using a three-layer oil technique

A new method for the determination of ferrichrome binding to the FhuA transporter in the Escherichia coli outer membrane, ferrichrome accumulation in the periplasmic space, and ferrichrome transport into the cytoplasm was developed. Cells were separated from residual, soluble, radiolabeled ferrichrome by centrifugation in a micro-test tube containing three layers of nonmixable solutions of different densities. Cells in the upper aqueous layer passed through the middle silicone oil layer, but did not enter the underlying NaI layer, thereby accumulating on top of the NaI layer; soluble compounds remained in the upper aqueous layer. Cells were then easily recovered by centrifugation, and radioactivity was determined by liquid scintillation counting. Reproducible results for all applications tested were obtained without the need for any washing steps. The method was tested by determination of receptor binding and transport of ferrichrome with various FhuA mutants which, in contrast to their transport activity, showed only a weak binding of ferrichrome to FhuA and compared with the commonly used cellulose nitrate filter method. Similar transport rates were obtained with the two methods, but binding of ferrichrome to the mutated FhuA proteins and accumulation of ferrichrome in the periplasm could be measured only with the new method.

Flow observation in two immiscible liquid layers subject to a horizontal temperature gradient

Marangoni convection, driven by an interfacial instability due to a surface tension gradient, has become a significant problem in the crystal growth on the ground or in a microgravity environment. To suppress and control the convection is important for material processing. Especially in the crystal growth by liquid encapsulated czochralski or liquid encapsulated floating zone technique, in which the melt is encapsulated with an immiscible medium, Marangoni convection can occur on the liquid–liquid interface and on the gas–liquid free surface. In the present paper, experiments were carried out with a double liquid layer of silicone oil and fluorinert both in an open-boat system and in an enclosed system. Flow in a cavity subject to a horizontal temperature gradient was observed. An interactive flow near the interface was measured by using particle image velocimetry technique. The measured flow field seemed to agree sufficiently with the numerical prediction.

Experimental study of the gravity influence on the periodic thermocapillary convection around a bubble

The 3D periodic state, following the steady thermocapillary convection state, around an air bubble immersed in a low-Prandtl-number silicone oil layer under a heated wall was experimentally investigated on the ground and during parabolic flights. This oscillation was observed under reduced gravity conditions for the first time. Consequently, the initiation of this oscillation seems to be independent of gravity and so of buoyancy convection. The reduced and increased gravity conditions showed that the gravity level modifies the oscillation. Its frequency increases with the gravity level. The comparison with the results obtained on the ground shows the bubble aspect ratio is not a relevant parameter when the gravity varies.

Light-Enhanced Uptake of Metabolites in Mesophyll Protoplasts: Evidence for a Novel Pyruvate Transport System

) and sorghum (C4) leaves for the measurements of osmotic volume change and metabolite uptake. We first investigated whether the silicone oil layer filtering centrifugation method could be applied to the protoplasts. The density of the silicone oil was optimized (ρ =1.026) and 0.5M betaine was chosen as an osmoticum in the protoplast suspending medium. By using [14C] sorbitol and [14C] inulin as the marker of the medium carried over into the pellet, protoplast osmotic or internal volume was estimated to be 200–300 μl (mg Chl)−1, with the medium space in the pellet of 8–15 μl (mg Chl)−1. Lowering of the osmotic pressure of the medium induced protoplast swelling as expected. Light also induced swelling. Using this system, we could detect light-enhanced uptake of ascorbate, glutamate and pyruvate in both barley and sorghum protoplasts. Pyruvate uptake was far higher in barley than in sorghum and inhibited by various inhibitors, showed saturation kinetics and, therefore, seemed to be mediated by a translocator protein.

Influence of Injected Ar Gas on the Involvement of the Mold Powder under Different Wettabilities between Porous Refractory and Molten Steel.

This research studied the involvement of mold powder and the influence of argon gas injection by means of a silicon oil-water model experiment and a 3-D numerical model. In this experiment argon gas was injected into the submerged entry nozzle through two kinds of cylinder-like porous refractory with and without wax film on inner surface. Investigation indicates that injected argon influence the involvement of silicon oil by give rise to a strong fluctuation on the interface between the water and the silicon oil layer that was used to simulate the mold powder of the continuous casting process. Silicon oil was involved more easily when the porous refractory with wax film was used than that as the porous refractory without wax film was used. This is because injected argon gas through the porous refractory with wax film produced a gas curtain inside the nozzle and in turn caused unstable water flow inside the mold and a strong fluctuation of the silicon oil-water interface. The results of experiment and numerical simulation agree with each other when gas injection rate is small. The involvement behavior of the mold powder the continuous casting process is thought to be similar to that as porous refractory with wax film was used because in both cases the wettability between the liquid and the porous refractory is poor.

NMR decoration study of the mixed state in high- Tc cuprates

A systematic NMR decoration study of the field inhomogeneity in the mixed state of high- T c cuprates is presented. A thin layer of silicone oil formed around individual grains due to wetting was used as the NMR probe. We have measured the temperature dependence of the additional NMR line broadening Δw, caused by the field modulation in the mixed state. Using the relation Δw ≃ 1/ λ 2( T) we have determined the temperature dependence of the London penetration depth λ( T). The λ( T) variation can be characterized by a simple power law, λ 2(0) λ 2(T) = 1 − ( T T c ) n . We have obtained for YBa 2Cu 3O 7, Bi 2Sr 2Ca 2Cu 3O 10 and Bi 2Sr 2CaCu 2O 8 the power n = 3, 2.35 and 2.26 and the values λ(0) = 2500, 2400 and 3350 ± 10 A ̊ , respectively. These λ(0) values, derived from the fit, correspond to an average over different grain orientations. The power n decreases with an increasing anisotropy of the studied high- T c cuprates.

Electrical performance of non-ceramic insulators in artificial contamination tests. Role of resting time

The paper presents the results of an investigation on the electrical performance of artificially contaminated non-ceramic insulators as a function of resting time. Resting time is defined as the time interval between the application of contamination and start of testing. New (unaged), full scale, 69 kV non-ceramic insulators using different types of silicone rubber and ethylene propylene diene monomer (EPDM) rubber as weathersheds were studied. Their electrical performance was assessed using the clean fog technique. The applied voltage was kept constant throughout the test, while contamination severity and resting time were varied as parameters. The transfer of hydrophobicity through the contamination layer was demonstrated by flashover tests. This was also visually depicted by analyzing samples in a scanning electron microscope. The results show that resting time exerts little influence on the electrical performance of EPDM insulators. However, for silicone rubber insulators, resting time is shown to drastically improve its electrical performance. Experimental evidence indicates that the transfer or recovery process of hydrophobicity in silicone rubber insulators occurs as a progressive superposition of silicone oil layers with time. Thus, the net effect of resting such insulators before tests can be thought of as a gradual reduction of the effective contamination layer thickness. Such a reduction alters the way in which the contaminant layer interacts with external stressing agents, which could impact the insulator's electrical performance in service. In this work, an attempt has been made to identify and quantify the electrically significant changes introduced by a reduction in the effective contamination thickness. It is in the light of this reduced effective contamination layer that we explain how a seemingly wettable silicone rubber insulator is still able to hold the applied voltage without flashover.

An experimental investigation of the electrical breakdown phenomena of interface insulation in prefabricated‐type joints

AbstractTo establish the reliability of the insulating performance of prefabricated‐type joints (PJs), dielectric breakdown characteristics of interface insulation were studied.Using two types of electrodes, which simulate the interface configuration in an actual 275‐kV PJ, ac and impulse BDSs, together with long‐term performance of the interface, were evaluated under various conditions. Among the many factors which would influence the insulating characteristics of the interface, the effect of the silicone oil layer, as well as the applied external pressure, were examined. It was determined that the BDSs were influenced greatly by silicone oil application, by the applied interface pressure, and by the pretreatment of the surface of XLPE insulation. On the basis of the result of experiments, the functions of the silicone oil layer in the insulation interface of the PJ were examined.The authors concluded that the thinner silicone oil layer in the insulation interface is favorable for the establishment of the insulation interface of the PJ.

Histopathology of rabbit eyes with silicone-fluorosilicone copolymer oil as six months internal retinal tamponade

Silicone-fluorosilicone copolymer oil has low viscosity (175–185 cSt) and is heavier than water (density, 1·16 g cm −3). Short term retinal tolerance (within 2 months) of the silicone-fluorosilicone copolymer oil has been reported to be the same as that of currently used intraocular silicone oil. Ocular response of the purified silicone-fluorosilicone copolymer oil were examined clinically and histopathologically from 2·5 months to 6 months after vitreous cavity injection in rabbit phakic eyes, and compared the oil tolerance with that of purified silicone oil (0·97 g cm −3, 5000 cSt). The effects in anterior chamber also were examined within 4 weeks of the silicone-fluorosilicone copolymer oil injection in different rabbits. Silicone-fluorosilicone copolymer oil recovered from the vitreous cavity at 6 months was analysed for cholesterol and retinol content by high performance liquid chromatography. Because of its low viscosity, silicone-fluorosilicone copolymer oil was easy to inject and remove from the vitreous cavity with a 20-G needle. After the vitreous injection, discrete droplet formation by the silicone-fluorosilicone copolymer oil occurred more easily than by silicone oil. Medullary ray detachment was seen in a silicone oil-, and some silicone-fluorosilicone copolymer oil-injected eyes at 4–6 months. Histopathologically, after 3–6 months disappearance of outer plexiform layer and disorganization of the photoreceptor layer of silicone oil-, and silicone-fluorosilicone copolymer oil-injected eyes were seen in the superior and the inferior retina, respectively. Migration of the photoreceptor cell nuclei to the photoreceptor layer was found in the inferior retina of silicone-fluorosilicone copolymer oil-injected eyes at 5–6 months. Small droplets ingested by mononuclear cells were found in the vitreous cavity or preretina at 4–6 months in silicone-fluorosilicone copolymer oil-injected eyes. After the anterior chamber injection, silicone-fluorosilicone copolymer oil induced endothelial cell damage in the area where the oil contacted continuously. Retinol and cholesterol were identified in silicone-fluorosilicone copolymer oil removed from the vitreous cavity. Silicone-fluorosilicone copolymer oil may be useful as an intraoperative device in retinal detachment surgery and as a short term (up to about 2 months) retinal tamponade but we do not recommend it for long term retinal tamponade.

Study of the vortex state in YBa 2Cu 3O 7 and Bi 2Sr 2CaCu 2O x by the NMR decoration technique

The field inhomogeneity in the mixed state of a type II superconductor can be studied by the NMR decoration technique. We calibrated this technique using the classical superconductor Nb 3Sn [1]. As NMR probe we have taken thin silicone oil layers formed around the individual grains of superconducting powder. We measured the additional NMR line broadening of the oil as a function of temperature. This method is applied to study the characteristic field inhomogeneity of YBa 2Cu 3O 7 (YBCO) and Bi 2Sr 2CaCu 2O x (BSCCO) powders in the field cooled and zero field cooled regimes. For YBCO, the temperature dependence of the additional line broadening follows the temperature dependence of the penetration depth given by the fwo fluid model. The penetration depth λ 0=3040 Å for YBCO derived from the two fluid model fit, is an average over different grain orientations and lies in between the values λ ab and λ c reported previously [2]. For BSCCO, the additional line broadening vs temperature strongly deviates from the predicton based on the two fluid model.

Dental plaque inhibition by a combination of triclosan and polydimethylsiloxane (silicone oil)

It has previously been shown that a toothpaste which contains triclosan and polydimethylsiloxane (silicone oil) improved gingival health in a test panel with established gingivitis more markedly than usually observed when testing commercial triclosan-containing toothpastes. In the present study the mode of action of combinations of silicone oil and triclosan was investigated. An in vitro experiment showed that triclosan was retained in a thin layer of silicone oil on the inner surfaces of test tubes that had been treated with the combination of triclosan and silicone oil. This triclosan was slowly released and inhibited the growth of bacteria in the test tubes. Silicone oil alone and in combination with triclosan was able to inhibit polysaccharide adhesion to the test tubes in the presence of a strain of Streptococcus sobrinus and a sucrose-containing medium. Corresponding in vivo experiments showed similar results; teeth topically treated with silicone oil and triclosan showed a marked plaque reduction, and those treated with silicone oil alone showed a moderate reduction, as compared with a placebo. The silicone oil plus 0.3% triclosan combination inhibited plaque formation also on proximal surfaces. It appears likely that this combination provides a reservoir of triclosan in the thin layer of silicone oil which binds strongly to teeth because of its low surface tension. Triclosan is then slowly released into saliva because of its low solubility in this fluid.