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981.
Dong-Jin Shim Hong-Wei Sun Vengallatore S.T. Spearing S.M. 《Journal of microelectromechanical systems》2006,15(1):246-258
The design, fabrication, and testing of microfluidic joints consisting of Kovar metal tubes attached to silicon using borosilicate glass for high pressure microelectromechanical systems devices are presented. The MIT microrocket, which requires microfluidic joints to sustain pressures of at least 12.7 MPa and temperatures in excess of 700 K, is used to demonstrate the feasibility of the glass sealing methodology. A key concern in such joints is the occurrence of cracks due to residual stresses during fabrication, which can affect the load-carrying capability. To obtain a better understanding of the damage and failure characteristics, a hierarchical approach was taken. First, two types of joint configurations with several glass compositions and geometries were considered at the joint-level. Axial tension and pressure tests were performed, and finite element models were used to obtain the residual stress field and to predict failure loads based on linear elastic fracture mechanics. Subsequently, tests were performed on actual and dummy microrockets to validate the methodology at the device-level. Key observations include the importance of bonding between the Kovar tube and the silicon sidewall, which can help increase joint strength, and the detrimental effects of joint proximity under differential pressure loading and manufacturing defects in multiple joint specimens. In addition to specific experimental and analyses results that allow a physical understanding of the damage and failure mechanisms, another key contribution of this work is the overall insight of the design and analysis of reliable glass-sealed microfluidic packages. This insight will help one make better design and process selections for packages in other high-pressure silicon-based MEMS applications. 相似文献
982.
Xi-Wen Liu Hyun Jung Shim Chan Wok Son Mi Yeon Kim Min Hee Kim Hui Song Cui Cheon Ho Park Dai-Eun Sok Mee Ree Kim 《European Food Research and Technology》2009,228(3):411-416
Lysophospholipase D (lysoPLD) is known to convert lysophosphatidylcholine (LPC) to lysophosphatidic acid (LPA). In this study,
we examined the inhibitory effect of fish egg extracts, containing lipids, on bovine lysoPLD activity. Fish eggs extracts
were tested for the inhibition of lysoPLD activity, and the inhibitory action was expressed as 50% inhibitory concentration
(IC50). Among fish egg extracts of 20 fish species, the most potent inhibition was expressed by Hairtail egg extract (IC50, 0.07 ± 0.01 mg egg weight/mL), followed by extract of Spanish mackerel egg extract (0.11 ± 0.02 mg egg weight/mL) and extract
of Pacific saury egg (0.48 ± 0.03 mg egg weight/mL). In ESI/MS analysis, major lysoPLD-inhibitory lipid components in egg
extracts were identified to be species of LPC, LPA and fatty acid. From these results, it is suggested that the strong inhibition
of lysoPLD activity by fish egg extracts might be ascribed to the presence of lysophospholipids. In a separate study, enzymatic
oxidation using lipoxygenase or non-enzymatic oxidations such as HOCl oxidation or Cu2+-catalyzed oxidation enhanced the inhibitory activity to some extent, suggesting that the oxidation of polyunsaturated lysophospholipids
might contribute to the increase of lysoPLD-inhibitory action. Taken together, it is suggested that fish eggs may contain
potent lipid inhibitors of lysoPLD, and that the inhibitory action of lipid inhibitors was enhanced by oxidative process. 相似文献
983.
The partial placement of electromagnetic bandgap unit cells only near the sources of noise is proposed as a means of both suppressing the noise propagation and minimising the effects of a discontinuous reference plane. The simultaneous switching noise suppression performance of the proposed structure is verified and investigated experimentally. 相似文献
984.
Natural graphite, which is used as an anode material in lithium-ion batteries, is thermally treated to improve its cycleability and reduce irreversible reactions with the electrolyte. Natural graphite is treated in air at 550 °C. The weight loss increases when the thermal oxidation time is increased. The BET surface area of the graphite decreases with increasing weight loss. The cycleability and efficiency of the thermally oxidized natural graphite improves significantly. Thermal oxidation decreases the irreversible capacity for side-reactions with the electrolyte on the first cycle. By contrast, it does not change the reversible capacity and rate capability. The improvement in the cycleability after thermal oxidation may be due to the removal of imperfect sites on the graphite. 相似文献
985.
A novel method for the synthesis of transition-metal boride nanopowder has been developed using a mechanochemical reaction between LiBH4, LiH and transition-metal chloride (TiCl3 and VCl3) by high energy ball milling. This method successfully produces TiB2 and VB2 particles dispersed within a soluble LiCl matrix. Subsequent washing with distilled water, ethanol and acetone to remove the LiCl matrix phase yields TiB2 and VB2 nanopowders of 15-60 nm particle size. From the X-ray diffraction patterns and high resolution transmission electron microscopy image, it is found that each particle is polycrystalline consisting of 3-5 nm crystallites. Neither particle nor crystallite size are increased significantly after heating at 680 °C. 相似文献
986.
Jaekyung Yoon Sanghyun Bae Eunjung Shim Hyunku Joo 《Korean Journal of Chemical Engineering》2007,24(6):1031-1036
In this work, Pt- and Ru-deposited, nitrogen-substituted TiO2 were prepared and characterized by the discoloration of MB and H2 evolution. The characteristics were evaluated in terms of methylene blue (MB) discoloration, open circuit voltage (OCV),
photocurrent (I
ph
), and hydrogen production. First, the Pt-deposited TiON revealed comparable activity in MB discoloration, while both TiONs
resulted in somewhat less activity than P25. Second, an external bias was systematically applied to electrodes made of the
prepared samples, resulting in −0.41∼0.51 OCV, −400∼400 μA and noticeable hydrogen evolution above 300 μA in absolute value
when a bias of −1.5∼1.5 V was applied to the working electrode of P25. The electrolyte and light intensity affected the light-responsive
characteristics of the photocatalysts, confirming the relationship between OCV, I
ph
and H2 and that metal deposition slightly inhibited the I
ph
and H2 evolution while Ru-deposited TiON did not degrade MB effectively. 相似文献
987.
988.
Synthesis of functionalized SBA-15 with ordered large pore size and its adsorption properties of BSA 总被引:2,自引:0,他引:2
Thi Phuong Binh Nguyen Jae-Wook Lee Wang Geun Shim Hee Moon 《Microporous and mesoporous materials》2008,110(2-3):560-569
SBA-15, mesoporous material, is a very excellent candidate for drug delivery system because its pore size is easy to control according to synthesis conditions and the presence of swelling agent. In this study, a known swelling agent, 1,3,5-trimethylbenzene (TMB), was used to increase the pore size with increased aging temperature and prolonged aging time. Furthermore, 3-aminopropyltriethoxysilane (APTES) was incorporated on SBA-15 surface via post synthesis method to separate protein effectively. The samples were characterized by X-ray diffraction (XRD), nitrogen adsorption and desorption analyses, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier Transform Infrared (FT-IR). Adsorption capacity increased with temperature at the isoelectric point (pI) of bovine serum albumin (BSA) regardless of the pore size of SBA-15 samples. Release studies were carried out in the range of pH from neutral to basic solution on unmodified and amine-modified samples. In addition, the adsorption mechanism was investigated by employing the pseudo-first order, pseudo-second order, and intraparticle diffusion models. 相似文献
989.
For pt. I see ibid., vol.16, no.3, pp.6-12 (2000). This article is the second in the series of four related to digital signal processing to enhance partial discharge (PD) detection. In the first overview paper, several methods of removing noise from PD measurements were discussed briefly. In this paper, signal acquisition utilizing time-domain sampling, analog-to-digital (A/D) conversion (quantizing and coding), and signal reconstruction in the context of PD detection will be discussed 相似文献
990.