Showing papers on "Surface-area-to-volume ratio published in 2008"

Improvement in surface degradation properties of polymer composites due to pre-processed nanometric alumina fillers

Abstract: Insulating materials in power apparatus are often exposed to surface discharges in the course of normal operation, resulting in deterioration of the material surface. In an earlier work, the authors have shown that the inclusion of nanometric particles (Al2O3) improves the ability of a polymeric dielectric (epoxy) to resist degradation when exposed to surface discharges. In the current work, the effect of pre-processing the alumina nanoparticles before preparation of the composite, is investigated. Laser Surface Profilometry (LSP) was used to measure the degradation of the composite specimens after exposure to surface discharges. The use of a surfactant, viz. Sodium Dodecyl Sulfate (SDS) was found to be ineffective. However, the simple action of heating the nanoparticles before use, improved the resistance of the bulk composite to surface discharges. Further, the particles were functionalized using 3-glycidoxy-propyltrimethoxysilane (GPS). This process greatly enhanced the ability of the nanocomposite to resist surface degradation. In fact, best results were obtained when the particles were first heated and then coated with GPS. Fourier Transform Infra-Red (FTIR) spectroscopy and other techniques were used to investigate chemical changes at the particle-epoxy interfaces. A direct correlation was observed between the improvement of the resistance of the composite to surface degradation and the ability of the pre-processed nanoparticles to form strong bonds with the neighboring epoxy. Effect of pre-processing particles of larger dimensions (platelets) was negligible compared to nanoparticles, indicating the possible importance of the interfacial surface to volume ratio of the fillers.

Surface stress effects on the resonant properties of silicon nanowires

Abstract: The purpose of the present work is to quantify the coupled effects of surface stresses and boundary conditions on the resonant properties of silicon nanowires. We accomplish this by using the surface Cauchy–Born model, which is a nonlinear, finite deformation continuum mechanics model that enables the determination of the nanowire resonant frequencies including surface stress effects through solution of a standard finite element eigenvalue problem. By calculating the resonant frequencies of both fixed/fixed and fixed/free ⟨100⟩ silicon nanowires with unreconstructed {100} surfaces using two formulations, one that accounts for surface stresses and one that does not, it is quantified how surface stresses cause variations in nanowire resonant frequencies from those expected from continuum beam theory. We find that surface stresses significantly reduce the resonant frequencies of fixed/fixed nanowires as compared to continuum beam theory predictions, while small increases in resonant frequency with respect to continuum beam theory are found for fixed/free nanowires. It is also found that the nanowire aspect ratio, and not the surface area to volume ratio, is the key parameter that correlates deviations in nanowire resonant frequencies due to surface stresses from continuum beam theory.

Microfluidic differential resistive pulse sensors.

Abstract: This study demonstrates an on-chip resistive pulse-sensing scheme with a design of symmetric mirror channels, which significantly reduces the noise and achieves better signal-to-noise ratio. Polystyrene particles of different sizes have been detected with the developed sensing scheme and a record low volume ratio of the particle to the sensing channel, or 0.0004%, has been detected with particles of 520 nm in diameter in a sensing aperture of 50×16×20 μm3. This volume ratio is about ten times lower than the lowest volume ratio reported in the literature including that specified for commercial Coulter counters.

Nanostructured Aluminium Hydroxyfluorides Derived from β-AlF3

Abstract: Microwave-assisted synthesis has been applied for the preparation of aluminum hydroxyfluorides derived from β-AlF3. In the course of obtaining high-surface-area and homogeneous nanocrystallites, several key parameters have been adjusted. A relationship between the OH/F molar ratio and the stabilized allotropic forms has been pointed out. The surface area has been monitored depending on the water/isopropanol volume ratio. The microstructural properties of the as-prepared material have been thoroughly investigated highlighting X-ray line broadening arising from strains and size effects. It has been concluded from X-ray diffraction data refinements and TEM results that the prepared crystallites possess a platelet shape with an average particle size of 15 nm associated with a high surface area of 82 m2 g−1. The occurrence of hydroxyl groups inside the network has been detected by FTIR spectroscopy and considered angles and bond distances are probably located in peculiar crystallographic sites, i.e., 8f (F1) a...

Drying of salt solutions in porous materials: Intermediate-time dynamics and efflorescence

Abstract: Drying of salt solutions leads to the accumulation of salt at any surface where evaporation occurs. When this drying occurs within porous media, the precipitation of salts or efflorescence is generally to be avoided. A one-dimensional model for the drying processes in initially saturated porous materials was presented by Huinink et al. [Phys. Fluids 14, 1389 (2002)] and analytical results were obtained for short times when the concentration distribution evolves diffusively. Here, we present analytical results for intermediate times when convective and diffusive fluxes balance. Moreover, the approach is extended to symmetrical geometries and is generalized for porous objects with arbitrary shape, which highlights the role of the surface area to volume ratio. Estimates for the Peclet number dependence of the maximum salt concentration at the surface are obtained and the conditions that allows to avoid efflorescence are characterized.

Simulation of fluid flow in hydrophobic rough microchannels

Abstract: Surface effects become important in microfluidic setups because the surface to volume ratio becomes large. In such setups the surface roughness is not any longer small compared to the length scale of the system and the wetting properties of the wall have an important influence on the flow. However, the knowledge about the interplay of surface roughness and hydrophobic fluid-surface interaction is still very limited because these properties cannot be decoupled easily in experiments. We investigate the problem by means of lattice Boltzmann (LB) simulations of rough microchannels with a tunable fluid-wall interaction. We introduce an 'effective no-slip plane' at an intermediate position between peaks and valleys of the surface and observe how the position of the wall may change due to surface roughness and hydrophobic interactions. We find that the position of the effective wall, in the case of a Gaussian distributed roughness, depends linearly on the width of the distribution. Further, we are able to show that roughness creates a nonlinear effect on the slip length for hydrophobic boundaries.

Atomistic structure dependence of the collective excitation in metal nanoparticles.

Abstract: From a simple time-dependent tight-binding model, we calculate the absorption spectra of a series of metallic nanoparticles of varying size and shape. Spheres and spheroids of varying aspect ratios as well as a number of polyhedral particle shapes are studied. The frequency of the maximum absorption is found to scale linearly with the surface to volume ratio of the particle with a slope and intercept, which depends on particle shape, in particular, on the deviation from sphericity. In the case of spheroids, the shifts of the two different plasmon peaks that are observed are characterized as a function of the aspect ratio. The influence of shape is seen to be a determining factor for the frequency of the plasmon resonance. The influence of adatoms is studied. Linear relations between surface adatom concentration and the width of the spectral feature as well as the peak energy are observed.

Applying the experimental statistical method to deal the preparatory conditions of nanometric-sized TiO2 powders from a two-emulsion process

Abstract: Nanometric-sized titanium oxide powders have been synthesized successfully through the two-emulsion method. It was found that the anatase phase is formed at 400 °C and converted to rutile phase as heat-treated at 700 °C. The synthesized TiO 2 powders exhibit particle sizes at 10–30 nm, in a specific surface area of about 30–88 m 2 /g. Furthermore, the surface response method (including Box-Behnken design) was applied to deal with the preparatory conditions of the two-emulsion process. It reveals that the optimal preparatory conditions were obtained at the volume ratio of surfactant/ n -hexane = 0.03, volume ratio of water/oil = 0.04, molar ratio of acetylacetone/titanium isopropoxide = 4, molar ratio of isopropanol/titanium isopropoxide = 23.1. By combining the optimal settings of those variables, a nanometric-sized TiO 2 powder has been obtained with specific surface area of 96 m 2 /g. It demonstrates the photocatalytic degradation of methylene blue solution effectively by exposing the as-synthesized TiO 2 powders in aqueous solution under ultraviolet light.

Method for surface treating substrate and plasma treatment apparatus

Abstract: A method for surface treating a substrate includes supplying first plasma generated by using nitrogen gas and oxygen gas toward a substrate surface to surface treat the substrate surface in air. In the method, a volume ratio of the oxygen gas to a total supply of the nitrogen gas and the oxygen gas is smaller than a volume ratio of oxygen contained in air.

One-stage medium-pressure hydrogenation method for producing food-level white oil

Abstract: The invention relates to a method for producing food-grade white oil through a medium pressure hydrogenation. After raw oil and hydrogen gas are mixed, the hydrogenation reaction is performed, under the reaction conditions as follows: the temperature is 180 to 320 DEG C, the hydrogen partial pressure is 4.0 to 1.0 Mpa, the volume space velocity is 0.1 to 1.0h , and the hydrogen and oil volume ratio is (200-1000):1; the catalyst pore volume is 0.4 to 1.0ml.g , and the specific surface area is 150 to 280m .g ; the content of active component metal Ni is 1 to 55 percent of the total weight of the catalyst, the carrier adopts the mixture of macropore aluminium oxide and microbore aluminium oxide, the weight ratio of the both is (2-4):1, silicon or/and phosphor is (are) added in the carrier as the additive, the content of the silicon in aluminium oxide is 1 to 20 percent, the content of the phosphor is 1 to 10 percent, or the content of the silicon and the phosphor is 1 to 10 percent. The method has the advantages that the process is simple, the operation is convenient, the investment and the operation costs are low, the raw material source is wide, and the method is applied to the production of the food-grade white oil.

Amplitude damping for single-qubit system with single-qubit mixed-state environment

Abstract: We study a generalized amplitude damping channel when environment is initially in the single-qubit mixed state. Representing the affine transformation of the generalized amplitude damping by a three-dimensional volume, we plot explicitly the volume occupied by the channels simulatable by a single-qubit mixed-state environment. As expected, this volume is embedded in the total volume by the channels which is simulated by a two-qubit enviroment. The volume ratio is approximately 0.08 which is much smaller than 3/8, the volume ratio for generalized depolarizing channels.

Light diffusion plate, light diffusion layer forming liquid, and light diffusion plate manufacturing method

Abstract: A light diffusion plate arranged in an immediately-below type backlight unit used for a liquid crystal display or the like has problems that it does not have sufficient diffusion performance and it is difficult to increase its size. Moreover, it is difficult to manufacture the light diffusion plate at a low cost. Provided is a light diffusion plate including a glass substrate and a light diffusion layer formed on the glass substrate. The light diffusion layer is formed by a matrix and a light diffusion member. The absolute value Δn of the difference between the refractivity values of the matrix and the light diffusion member is not smaller than 0.05 and not greater than 0.5. The volume ratio of the light diffusion member in the light diffusion layer is 30% or above.

Factors Affecting In Vitro Bioactivity of Glasses

Abstract: In this work we summarize the most important findings of the influence of glass composition, sample shape and fluid circulation on in vitro behavior of bioactive glasses in the system Na2O-K2O-MgO-CaO-B2O3-P2O5-SiO2. The sample shapes included plates, particulates, powdered glasses, glass fibers and sintered cones with interconnected porosity. The in vitro bioactivity was measured as the changes observed in the immersion solution, SBF, and the formation of reaction layers on the samples at 4 to 168 h immersion. A lower surface area to volume ratio gave smaller changes on the ion concentrations and pH of the immersion solution but thicker reaction layers on the glass surfaces. In particulate systems with circulating fluid the pH gradients in SBF were lower but surface layers more even than in static systems. The influence of glass composition on reaction layer formation as suggested by glass plates correlated with the in vitro behavior of glass particulates larger than 250 µm, porous cones and fibers when using similar SA/V ratio.

Method for preparing network interpenetration type diamond coat multi-pore electrode

Abstract: The invention discloses a preparation method for a mesh interpenetration type diamond coating porous electrode which adopts a porous activated carbon material produced by carbonaceous mesophase and different filling materials as a base, the liquid acetone as a carbon source, and the hydrogen as a carrier, wherein, the honeycombed diamond coating porous electrode is prepared on a multi-pore activated carbon substrate by using microwave plasma chemical vapor deposition (MPCVD) process; a reaction chamber is extracted into vacuum and then is filled with reaction gas, the pressure in the reaction chamber is adjusted, then the diamond coating is deposited by chemical vapor deposition method (CVD); the process parameters are that: the pressure is between 2 and 4 kPa, the total flow of the gas is between 90 and 120 ml/m, the ratio of acetone/hydrogen is between 1 and 3 percent (volume ratio). The invention solves the problems that the diamond porous electrode has high preparation cost, complex process and limited electrode area.

Thermally conductive adhesives and heat radiation module using the same and power converter

Abstract: PROBLEM TO BE SOLVED: To provide thermally conductive adhesives that can improve thermal conductivity without degrading adhesivity and insulation and can be also used appropriately to connect a semiconductor device and a heat dissipating member, and to provide a heat radiation module using the same and a power converter. SOLUTION: The thermally conductive adhesives is used to connect a semiconductor device and a heat dissipating member directly or by means of other members. It contains an insulation resin, aluminum nitride particles of 15 to 30 μm in average particle size and nearly spherical alumina particles of 0.5 to 2 μm in average particle size, and the mixing ratio (volume ratio) of the aluminum nitride particles and the nearly spherical alumina particles is 70:30-80:20. In addition, the total volume of them is 60-70 vol% of that of the insulation resin, the aluminum nitride particles and the alumina particles. COPYRIGHT: (C)2009,JPO&INPIT

Surface layer fine granular steel part and producing method therefor

Abstract: PROBLEM TO BE SOLVED: To provide a surface layer fin granular steel part having high yield strength equal to or higher than a conventional quenching and tempering treated material, and to provide a producing method therefor. SOLUTION: This surface layer fine granular steel part contains, by mass%, of 0.45-0.60% C, 0.01-0.60% Nb, 0.10-1.50% Si, 0.40-3.0% Mn, ≤2.0% (containing 0) Cr, ≤0.10% P, 0.001-0.15% S, 0.003-0.025% N and the balance Fe with inevitable impurities and is observed that till at least 1.0mm depth under a part or the whole surface, the whole average grain diameter of a packet of protectoid ferrite crystal grain, bainitic ferrite crystal grain and tempering martensite , surrounding the large angle granular boundary having 15° or more the orientation differential angle, is 5μm or lower, and this part is the ferrite-bainite-martensite-based structure having 30% or lower of the volume ratio of the proeutentoid ferrite crystal. COPYRIGHT: (C)2008,JPO&INPIT

Decomposing Sodium Aluminate by Solventing-out Process to Prepare Aluminium Hydroxide

Abstract: The novel method of decomposing sodium aluminate solution to aluminium hydroxide using solventing-out crystallization has been proposed and ultra-fine aluminium hydroxide particles were prepared by the method.Effects of crystallization temperature,solution concentration,molar ratio and volume ratio of the solventing-out process were investigated.The experimental results indicated that qualified particles with the decomposition rate of more than 90% were obtained at the condition of lower crystallization temperature,1∶1 volume ratio solvent,sodium aluminate solution concentration of 100～200g/L Al2O3 with the molar ratio of 1.4~2.0.In addition,the obtained product was characterized by SEM,laser diffraction-based particle size analyzer,XRD and TG-DTA.The results showed that the product was bayrite tabular crystal with uniform morphology,narrow particle size distribution and high purity.

Gallium nitride substrate and method of manufacturing the same

Abstract: A gallium nitride substrate is provided to reduce cracks capable of being generated in mechanical machining of a substrate by adjusting the size of a hillock formed on the surface of a gallium nitride substrate. A buffer layer(120) is formed on a base substrate(110). A gallium source and a nitrogen source are supplied to a growth furnace until the volume ratio(V/III group ratio) of the nitrogen source to the gallium source becomes a first volume ratio so that a gallium nitride layer(130) with a predetermined thickness is grown on the buffer layer. A gallium source and a nitrogen source are supplied to the growth furnace until the volume ratio of the nitrogen source to the gallium source becomes a second volume ratio higher than the first volume ratio so that a surface layer is formed on the gallium nitride layer. The process for forming the buffer layer can include the following steps. Ammonia gas is supplied to the growth furnace. Mixture gas of ammonia and hydrogen chloride is supplied to the growth furnace. Ammonia gas is supplied to the growth furnace.

Catalytic composition for hydrocracking and method of converting hydrocarbon raw material to low-boiling point material

Abstract: FIELD: chemistry. ^ SUBSTANCE: description is given of a catalytic composition for hydrocracking, which consists of a carrier, containing zeolite with a faujasite structure with cell dimension ranging from 24.10 to 24.40 A , volume ratio of silicon oxide:aluminium oxide (SAR) of approximately 12, and surface area of at least 850 m2/g, according to the BET and ASTM D 4365-95 measurement method on adsorption of nitrogen with p/po 0.03 value, and volume of micropores of at least 0.28 ml/g, hydrogenating component - at least one metal, chosen from group VIB and VIII metals, and optionally a binding substance. The catalytic composition is obtained using a method which involves a) preparation of the initial zeolite with faujasite structure with ratio of silicon oxide to aluminium oxide ranging from 4.5 to 6.5 and content of alkali less than 1.5 wt %; b) hydrothermal treatment of the above mentioned zeolite at temperature of 600-850°C and partial pressure, coming from an external source, in the range of 0.2-1 atm for a period of time, sufficient for obtaining intermediate zeolite with cell dimension of 24.30-24.45 A ; c) contacting intermediate zeolite with an acidifying solution, containing an acid and optionally an ammonium salt, under conditions conducive for obtaining zeolite with large surface area of faujasite structure with cell dimension in the range 24.10-24.40 A , volume ratio of silicon oxide:aluminium oxide greater than 12 and surface area of at least 850 m2/g, according to the BET and ASTM D 4365-95 measuring method, on adsorption of nitrogen with p/po 0.03 value, and volume of micropores of at least 0.28 ml/g and d) optional mixing of the above mentioned zeolite with a binding substance and/or a second cracking component, extrusion and baking; and e) adding at least one hydrogenating component to zeolite from stage (c) or to a catalyst at stage (d) or after it. Description is also given of a method of converting hydrocarbon raw material to low-boiling point materials, by contacting the raw material with hydrogen at high temperature and pressure in the presence of the above mentioned catalyst. ^ EFFECT: obtaining a catalytic composition with high selectiveness on average disciplines. ^ 10 cl, 5 tbl, 3 ex

Porous fired body and manufacturing method thereof

Abstract: A porous fired body including a structure that aggregates are bonded by a bonding material, wherein the aggregates include oxide particles having a larger thermal capacity per unit volume than an SiC particle and SiC, the bonding material includes metallic Si, volume ratio of the metallic Si in the whole porous fired body is between 8 and 43% by volume, volume ratio of the particles of the oxide in the whole aggregates is between 14 and 55% by volume, the SiC particles and the oxide particles respectively include one or more particle groups, and an average particle size of each particle group is within a range of between 5 and 100 μm.

Resin ceramic composite material, method for producing the same, composite material sheet, film capacitor and multilayer capacitor

Abstract: PROBLEM TO BE SOLVED: To obtain a resin ceramic composite material that has a relatively high dielectric constant and is suitable for forming the dielectric layer of a multilayer capacitor. SOLUTION: The resin ceramic composite material comprises ceramic particles in the volume ratio of 60-70% dispersed in a resin. The ratio of the number of neckings between ceramic particles and other ceramic particles is made ≥40% in a state in which when the diameter of the mutually contact part of adjacent first and second ceramic particles 1 and 2 is 2a and the diameter of the first ceramic particle 1 is 2R, a condition in which a/R is ≥0.3 is defined as the necking and in a surface element of 1μm square on an arbitrary cross section, the ratio of the number of surface elements in which the area ratio of the ceramic particles is ≥40% is made ≥90%. COPYRIGHT: (C)2008,JPO&INPIT

Morphology Control of AlPO_4-5 Molecular Sieve in Mixed-solvents System Under Microwave Irradiation

Abstract: The morphology control of AlPO4-5 crystals was achieved by microwave irradiation in mixed-solvents system.The results show that the aspect ratio of the AlPO4-5(c/a)crystals decreases significantly with the increase of the volume ratio of EG to H2O.Interestingly,the dumbbell shaped AlPO4-5 crystals can be obtained when the volume ratio of n-butanol to H2O reaches to 5∶1 in the mixed-solvents of n-butanol and H2O.With the addition of the crystal seeds,the size of the AlPO4-5 crystals decreases with the increase of the amount of crystal seeds and the stirring time.

Rolling-motion part and manufacturing method therefor

Abstract: PROBLEM TO BE SOLVED: To provide a rolling-motion part of which a long service life can be achieved in the case that the rolling motion part is used under lubricating atmosphere with foreign matter mixed therein without substantially increasing the cost and a manufacturing method of the same. SOLUTION: The rolling-motion part is formed by performing spheroidizing, processing, carburizing/nitriding treatment and finishing processing to a steel material composed of, by mass, 0.90-1.10% C, >0.35-0.70% Si, <0.80% Mn, 1.85-2.50% Cr, ≤0.12 ppm O. The average C content on the surface is 1.20-1.50 mass%, and the average N content on the surface is 0.10-0.60 mass%. The precipitation on the surface of ≥0.1 μm grain diameter is ≤0.6 μm average grain diameter and ≥700,000 pieces per 1 mm 2 number of grains and ≥10% area ratio. The volume ratio of the retained austenite quantity on the surface is 25-45% and the hardness on the surface is ≥750 Hv. The volume ratio of the retained austenite quantity in the inner part of the rolling-motion part is ≤20%. COPYRIGHT: (C)2009,JPO&INPIT

Electrode and actuator using the electrode

Abstract: [PROBLEMS] To provide an actuator which is stably operated in air, is inexpensive, and has a high level of displacement and initiation stress. [MEANS FOR SOLVING PROBLEMS] An electrode for use in an actuator using a polymeric solid electrolyte comprising an ion liquid and a polymer component. The actuator comprises an electrode using an alkali-activated carbon as an active material, a polymeric solid electrolyte comprising an ion liquid and a polymer component, and one electrode and the other electrode, which are located to hold the polymeric solid electrolyte therebetween, are not in contact with each other, and each satisfy the above requirement. The actuator can be deformed upon the application of a potential difference between the electrodes. The electrodes preferably satisfy, in addition to the above requirement, the requirement that the Ip/Io ratio, the total functional group content on the activated carbon surface, the BET specific surface area of the activated carbon, and the micropore total volume/mesopore total volume ratio are in respective ranges.

New cleaning method for mask and mask blank

Abstract: PROBLEM TO BE SOLVED: To provide a method using an alkaline based composition which is used in a pre-treatment step of the crystalline base-material surface, usable even for a photo-mask usage and has a various pH range and conductivity. SOLUTION: The cleaning method of the base-material surface enables the treatment of the base-material using a ud SC1 composition which has NH 4 OH, H 2 O 2 and a deionized water by a volume ratio of NH 4 OH:H 2 O 2 :H 2 O=1:2:200-1:1:100, and pH of 8-12, and then treatment of the base-material using a nonionic detergent composition which has a nonionic detergent and the deionized water by the volume ratio of 1-100, and pH of 8-11, wherein pH of the ud SC1 is higher than pH of the nonionic detergent composition. COPYRIGHT: (C)2008,JPO&INPIT

Raman-Spectroscopy for Measuring Chemical Reactions in Micro Reactors

Abstract: Micro heat exchangers, micro mixers and micro reactors have gained importance in chemical, pharmaceutical and life sciences applications. Due to the large surface to volume ratio these devices provide efficient mass and heat transfer. This results in greater selectivity and higher yield for chemical reactions. The Institute for Micro Process Engineering is working on the development, manufacturing, and testing of micro channel devices mainly manufactured of stainless steel, where channel widths and depths lie in the range of 0.2 mm. In order to obtain a better understanding of the physical and chemical processes within such components and to optimize these devices it is necessary to get a look into these micro channels during a mixing process or a chemical reaction. For this purpose laser Raman spectroscopy can be applied. This method is very selective for individual chemical compounds and allows a spatial resolution better than 0.01 mm. Figure 1 shows the experimental setup. The light of an air cooled cw argon ion laser is focused by a microscope objective into a micro channel, measuring the Raman bands over its cross section at several distances from the mixing point. A spectrograph with a CCD-array detects the Raman light, which consists of lines that are characteristic for the chemical compounds flowing through the micro channels and can therefore be used to calculate their concentrations.Copyright © 2008 by ASME