New approach to enhance adhesions between carbon nanotube emitters and substrate by the combination of electrophoresis and successive electroplating

Complementary electroplating combined with electrophoresis enhanced the field emission characteristics of emitters by improving the adhesions between CNT emitters and substrate. The emitting current of the CNT emitters prepared by our combined method increased nine times higher than that of CNT emitters prepared by electrophoresis only, since electroplating improved the adhesion of CNT emitters. During the life-time measurement for 10 h, the emitting current of CNT emitters fabricated by electrophoresis only was drastically decreased to 13% of the initial current, while that prepared by the combination of electrophoresis and successive electroplating decreased to 64% of the initial current. We suggest that our method is a promising approach for the efficient fabrication of reliable CNT emitters.     

Stabilization of PCC dispersions prepared directly in the mother-liquid after synthesis through the carbonation of (hydrated) lime

Various CaCO₃-based products are often used in the form of concentrated aqueous dispersions. This study investigates the stabilization of PCC dispersions prepared directly in the mother-liquid after the carbonation of (hydrated) lime through the adsorption of a commercial sodium polyacrylate dispersant. The results demonstrate that the composition of the mother-liquid, particularly the Ca²⁺ activity, profoundly influences virtually all processes pertinent to dispersion stabilization—from the initial charging of the CaCO₃ surface in base PCC dispersions, to the surface charge regulation and dispersion stabilization efficiency of the polyacrylate dispersing agent. Rising prominence of the counterion condensation effects in Ca²⁺ rich solutions limits the conditions conducive to the surface charge regulation through dispersant adsorption to an optimum pH range of about 8-11. Furthermore, dispersion stability analysis, based on the classical DLVO theory of colloid stability, and corroborated by experimental evidence in the form of particle size distribution analyses, also indicates that optimum stability conditions for such PCC dispersions are established with small dispersant doses (0.25-0.5% per dry weight) in the pH range of about 9-11.     

Performance evaluation of electrodewatering system for sewage sludges

A laboratory-scale electrodewatering system, incorporating an electric field as an additional driving force to conventional pressure dewatering, has been developed to decrease the water content of sludges generated in wastewater treatment. Consisting of a piston-type filter press, a power supply and a data acquisition system, the electrodewatering system’s performance was evaluated as a function of applied pressure, applied voltage, sludge type and filtration time. Experiments were carried out using sewage sludges with the electric field up to 120 V/cm and pressure ranging from 98.1 to 392.4 kPa. Electrodewatering involving a combination of electric field and pressure enhances both the dewatering rate and final dewatered volume. The final water content of sewage sludges in the electrodewatering system can be reduced to 62 wt%, as compared to 78 wt% achieved with the pressure filtration alone. The electrodewatering system shows the potential to be an effective method for reducing the water content in sludges.     

Development of a simple capillary electrophoretic determination of glucosamine in nutritional supplements using in-capillary derivatisation with o-phthalaldehyde

A simple capillary electrophoretic method was developed for the determination of glucosamine using in-capillary derivatisation. Glucosamine in commercial products was extracted with purified water. The CE separation was achieved on an uncoated fused-silica capillary using a 20 mM borate buffer (pH 9.2) containing 5 mM o-phthalaldehyde (OPA) and 5 mM 3-mercaptopropionic acid (MPA) at 25 kV, followed by UV detection at 340 nm. The detector response was linear (r² > 0.999) in the concentration range 10–1000 μg/mL. The limit of detection (LOD) was 1.3 mg/g. Spiked glucosamine recoveries at 50 and 100 mg/g level were 95.1% and 104.3%, respectively. The method was applied to 16 commercial products. The concentrations of glucosamine were 109–705 mg/g, and the ratios of detected glucosamine content to the labelled value were 88.8–124%. No significant bias was observed (r² = 0.989, p < 0.01), between results obtained by the proposed CE method and an official colorimetric method (Japanese Health Food & Nutrition Food Association).     

Electrophoretic deposition of manganese dioxide films using new dispersing agents

Abstract

Electrophoretic deposition (EPD) method has been developed for the fabrication of manganese dioxide (MD) films for application in electrochemical supercapacitors (ES). Anionic dyes were used as dispersing agents for MD synthesis and EPD. The adsorption of pyrogallol red (PGR) and aurintricarboxylic acid (ACA) dyes on MD was attributed to catecholate and salicylate type of bonding respectively involving chelation of Mn atoms on the MD particle surface. The adsorption of the dyes on MD allowed efficient dispersion, charging and deposition. The higher charge/mass ratio of ACA, compared to that of PGR, allowed deposition at lower dye concentration and lower voltages. The kinetics and mechanism of deposition were discussed. Electrochemical testing results showed that the MD films prepared by the EPD method are promising for application in ES. The highest specific capacitance of 409 F g^?1 was obtained at a scan rate of 2 mV s^?1.     

Rheological properties of African yam bean (Sphenostylis stenocarpa Hochst. Ex A. Rich.) calcium proteinate and isoelectric protein isolates

The rheological characterizations of African yam bean (Sphenostylis stenocarpa) protein dispersions were investigated. Isoelectrically precipitated protein-IP_alk and IP_salt isolates obtained from alkaline and salt extractions respectively were more soluble than calcium precipitated proteins (CaP_alk and CaP_salt) at pH 3, 7 and 8. Regression analysis showed that Power law, Casson and Bingham rheological models adequately described rheological behaviors of S. stenocarpa protein dispersion. However, Power law gave the best fit. The flow behavior indices (n), at different ionic strength, pH, and temperature media were less than unity, indicating that S. stenocarpa protein dispersion exhibited pseudoplastic behaviors under the conditions tested. Salt extracted proteins were more pseudoplastic than alkali extracted counterpart with n for salt extracted proteins (IP_salt & CaP_salt) lower than that of alkali extracted protein (CaP_alk & CaP_salt). This is a numerical indication that salt extracted S. stenocarpa proteins were of larger shear-thinning tendency than the alkali extracted proteins. The consistency coefficients, k of isoelectrically precipitated protein (0.305-0.327 Pasⁿ) were significantly (P < 0.05) higher than that of calcium proteinates in the range ranged 0.167-0.180 Pasⁿ. Both isoelectrically precipitated proteins and calcium proteinates exhibited yield stress, however, isoelectrically precipitated S. stenocarpa protein exhibited significantly (P < 0.05) higher yield stress (0.275-0.308 Pa) than the calcium proteinates (0.148-0.165 Pa). The effect of temperature on apparent viscosity of the proteins was evaluated using an Arrhenius-type equation. The activation energies (E_a) obtained were in the range 33-51.2 and 42.6-55.5 Jmol⁻¹ for calcium proteinate and isoelectrically precipitated protein respectively.     

功率晶体管芯片的电泳法玻璃钝化研究

本文介绍了电泳法淀积7801—5锌系玻璃粉钝化功率晶体管芯,并对电泳法原理、影响因素、玻璃粉烧结工艺进行了探讨;对钝化前后的器件做了测试;管芯反向漏电流得到改善,钝化后管芯分别在250℃和175℃温度下进行高温贮存试验取得满意结果.说明电泳法淀积7801—5锌系玻璃粉钝化工艺可提高半导体器件的稳定性和可靠性.     

不同荧光色桑蚕丝蛋白的电泳研究

本文用聚丙烯酰胺凝胶电泳法研究了不同荧光色桑蚕丝蛋白的电泳谱。发现:不同荧光色的绢丝蛋白的电泳谱,仅与其在蚕体中的部位有关,而与品种无关;不同荧光色的茧层丝胶具有相同的电泳谱;少量荧光性物质与丝胶蛋白发生了某种结合,但未影响丝蚕白的基本结构。     

Computational dynamics method for evaluating the mobility of charged biomolecules passing through the electrical potential field within the ion selective channel on an excitable membrane

A mathematical method is introduced to characterize the electrokinetic behavior (electrophoresis) of a biomolecular particle which passes through a specific channel pore on an excitable biological membrane. The basic approach was first proposed by Booth (1950). The system was described by an equation of continuity and an equation of motion in which the driving force involves the diffusion effect, the hydrostatic pressure, and the electrostatic potential. By assuming linear relations between the velocity and the applied electrical field, solutions for the potential, pressure, and velocity were given by a series expansion of the charges on the particle. To examine the influence of ions surrounding the particle and forming an ionic cloud, the Debye–Huckel parameter was introduced. As the thickness of the double layer around the particle increased, the potential, velocity, pressure, and viscosity were changed significantly. The maximum influence was obtained when the radius of the particle became equal to the thickness of the double layer. Although this theory is valid for a charged, spherical, nonconducting particle only, the method is available for evaluating the kinetic behavior of a biomolecule that passes through a channel pore on a cellular membrane.This work was presented, in part, at the 8th International Symposium on Artificial Life and Robotics, Oita, Japan, January 24–26, 2003     

Combined effects of thermophoresis and electrophoresis on particle deposition onto a wavy surface disk

In this paper, the coordinate transformation method is used to analyze the aerosol particle deposition from a stagnation flow onto an axisymmetric wavy disk under to the coupling effects of Brownian diffusion, convection, sedimentation, thermophoresis and electrophoresis. The transformed governing equations obtained by coordinate transformation are solved by the spline alternating-direction implicit method. Numerical results show that electrophoresis will increase the particle deposition effect. It reveals that the thermophoresis effect of the cold wall will induce a driving effort to force particles toward the wall and accelerate the deposition onto the wall. When Brownian diffusion and thermophoresis dominate the particle deposition process, the influence of the lumpy surface geometry will become stronger with the increase of the disk radius, and the mean particle deposition effect of the wavy disk would be less than that of the flat disk.