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81.
82.
Jung Sang Cho Jeong-Cheol Lee Shin Hye Chung Jeong Kon Seo Sang-Hoon Rhee 《Ceramics International》2014
The effect of grain size and density of hydroxyapatite particles, which were prepared by different spray-pyrolysis temperatures, on the sinterability of hydroxyapatite disk was investigated. Calcium phosphate solution (Ca/P ratio of 1.67 and 0.1 M concentration) was prepared by reacting calcium nitrate tetrahydrate and diammonium hydrogen phosphate solutions, and adding nitric acid. Spray-pyrolysis was carried out at 900 °C, 1200 °C, and 1500 °C at a carrier gas flowing rate of 10 L/min. The particles synthesized at 900 °C were large, hollow spheres with a hole at the outer surface, a broad size distribution, but had small grain sizes. Conversely, the particles synthesized at 1500 °C were small, solid spheres with a narrow size distribution, but had large grain sizes. The particles synthesized at 1200 °C had intermediate properties. A sinterability test conducted at 1100 °C for 1 h demonstrated that small and dense particles with large grain sizes showed a higher relative sintered density compared with large and hollow particles with small grain sizes. The results were explained in terms of the grain size and density of a particle, which were inversely and proportionally affected to sinterability. The practical implication of these results is that highly sinterable hydroxyapatite powders can be synthesized through spray-pyrolysis at a high temperature under a fixed initial concentration of calcium phosphate solution and flow rate of carrier gas. 相似文献
83.
Tae-Hyun Kim Jin-Goo Kang Jeong-Soo Sohn Kang-In Rhee Seoung-Won Lee Shun-Myung Shin 《Metals and Materials International》2008,14(5):655-658
The treatment of spent zinc-carbon batteries for the recovery of valuable metals followed by conversion to Mn−Zn ferrite has
been conducted employing two-stage alkali and acid leaching and co-precipitation method. In the first stage, leaching process
was carried out with 4 M NaOH, which resulted in a recovery of 63.4 %Zn and 0.1% Mn. Electrowinning of alkali leaching solution
containing 12.75 g/L Zn at a current density of 0.2 A/cm2 produced Zn metal of 15 nm to 30 nm size and 99.9% purity. The second stage leaching of residue with 3 M H2SO4 and 6 vol.% H2O2 at a solid/liquid ratio of 1∶10 indicated the leaching efficiency of 98.0% Zn, 97.9% Mn and 55.2% Fe. The obtained leaching
solution was finally adjusted to suitable mole ratios of Mn∶Zn∶Fe (1∶1∶4) by the addition of Zn and Fe sulfate salts followed
by pH control to produce Mn−Zn ferrite powder. The characterization of the ferrite powder showed uniform nano-crystalline
particles of about 20 nm size with spinel structure. 相似文献
84.
Sung-Chan Kim Baek-Seok Ko Tae-Jong Baek Byeong-Ok Lim An D. Dong-Hoon Shin Jin-Koo Rhee 《Microwave and Wireless Components Letters, IEEE》2005,15(10):652-654
The hybrid ring coupler was designed and fabricated on a GaAs substrate using surface micromachining techniques, which adopted dielectric-supported air-gapped microstrip line (DAML) structure. The fabrication process of DAML is compatible with the standard monolithic microwave integrated circuit (MMIC) techniques, and the hybrid ring coupler can be simply integrated into a plane-structural MMIC. The fabricated hybrid ring coupler shows wideband characteristics of the coupling loss of 3.57 /spl plusmn/ 0.22dB and the transmission loss of 3.80 /spl plusmn/ 0.08dB across the measured frequency range of 85 to 105GHz. The isolation characteristics and output phase differences are -34dB and 180/spl plusmn/1/spl deg/, at 94GHz, respectively. 相似文献
85.
S. Nourbakhsh O. Sahin W. H. Rhee H. Margolin 《Metallurgical and Materials Transactions A》1991,22(12):3059-3064
A pressure-cast NiAl composite reinforced with polycrystalline alumina (PRD-166) fibers containing 0.2 weight fraction of
partially stabilized zirconia was examined by optical and transmission electron microscopy (TEM). Fibers in the preform used
for casting were forced into contact, and fiber bonding occurred in a number of instances. Fiber volume fraction was increased
from an initial value of 0.4 to 0.6 as a consequence of the applied pressure. An explanation is offered for the interaction
of applied pressure, wetting angle, and the rigidity of the fiber preform on the final volume fraction of the fibers in the
composite. At the fiber/matrix interface, the alumina was free of zirconia particles. It is proposed that alumina grain growth
forced the zirconia into the molten NiAl, where it dissolved. As solidification took place, the concentration of zirconium
in the molten NiAl increased to a point where zirconium reacted with alumina to form zirconia again. 相似文献
86.
Wireless technologies are gaining increased acceptance as a viable technology within the industrial solution space. However, it is important for control system architects to fully understand not only the benefits but also the challenges and limitations of wireless technologies. The complex interrelationships between the various wireless technology characteristics require careful tradeoffs to be made in the design of the solution. This is especially true for applications that need to handle continuous data streams where high capacity is critical to maintain the scalability and reliability of the network. Although still relatively new, mesh networks have proven themselves to have significant advantages in robustness, scalability, and low-power consumption over other wireless technologies for use in industrial monitoring applications. Mesh networks employing PDR address the scalability challenges of wireless sensor networking that can limit implementation in production situations by significantly increasing overall packet-delivery rate and reducing network communication overhead. HC_WSN, an approach that will emerge as the important next trend in the wireless sensor networking industry, can be implemented in addition to PDR techniques and will further support the increasing number of applications that require the wireless sensor network to handle greater amounts of data. 相似文献
87.
H Kook JH Rhee SE Lee SY Kang SS Chung KW Cho YH Baik 《Canadian Metallurgical Quarterly》1999,365(2-3):267-272
Recently we reported that Vibrio vulnificus hemolysin, an exotoxin produced by V. vulnificus, dilates rat thoracic aorta via elevated cGMP levels without affecting nitric oxide synthase. We investigated the mechanism further by observing the guanylyl cyclase activities in cytosolic, membrane, unfractionated, or reconstituted preparations. Hemolysin did not activate guanylyl cyclase in the membrane or cytosolic fraction, while it activated guanylyl cyclase in unfractionated or reconstituted preparation. The increased activity was not inhibited by the HS-142-1, a microbial polysaccharide which antagonizes atrial natriuretic peptide receptor, or 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), a soluble guanylyl cyclase inhibitor. However, it was attenuated by 6-(phenylamino)-5,8-quinolinedione (LY 83.583), which inhibits the catalytic domain of both guanylyl cyclases, and by cholesterol, which blocks hemolysin-incorporation into the membrane. Removing ATP, a cofactor of particulate guanylyl cyclase, attenuated the activation and ATPgammaS, a non-phosphorylating analog, restored it. These results suggest that V. vulnificus hemolysin activates particulate guanylyl cyclase via hemolysin incorporation into the vascular smooth muscle cell membrane in cooperation with certain unidentified cytosolic component(s). 相似文献
88.
Se-Ra Won Deug-Chan Lee Seuk Hyun Ko Jang-Won Kim Hae-Ik Rhee 《Food research international (Ottawa, Ont.)》2008,41(10):952-956
The major proteins in honey have different molecular weights depending upon the honeybee species. To confirm the origin of major honey proteins, honey protein produced by Apis cerana or Apis mellifera were purified and analyzed by MALDI-TOF. Two major proteins were identified as a major royal jelly protein 1. Although two major proteins shared primary structure, they showed different molecular weights of 56 and 59 kDa, respectively. To discriminate the honeybee species producing honey using SDS–PAGE, artificial marker proteins, 56 and 59 kDa, were produced from Escherichia coli. Two artificial marker proteins were co-electrophoresed with honey samples and the difference in molecular weight was readily distinguished by SDS–PAGE. Therefore, the measurement of major proteins in honey is a useful method to discriminate the honey that produced from different honeybee species. 相似文献
89.
M. R. Geller D. J. Thouless S. W. Rhee W. F. Vinen 《Journal of Low Temperature Physics》2000,121(5-6):411-416
It has been known since the pioneering work of Onsager and Feynman that the statistical mechanics and dynamics of vortices play an essential role in the behavior of superfluids and superconductors. However, the theory of vortices in quantum fluids remains in a most unsatisfactory state, with many conflicting results in the literature. In this paper we review the theory of Thouless, Ao and Niu, which gives an expression for the total transverse force acting on a quantized vortex that is in apparent disagreement with the word of lordanskii and of Lifshitz and Pitaevskii. In particular, no transverse force proportional to the asymptotic normal fluid velocity was found. We use two-fluid hydrodynamics to study this discrepancy. 相似文献
90.
Effects of cooking methods on starch hydrolysis kinetics and digestion-resistant fractions of rice and soybean 总被引:1,自引:0,他引:1
In this study, we investigated the effects of cooking methods and digestion-resistant fractions on the starch hydrolysis kinetics
of rice and soybeans. The RS1 contents in unheated rice and soybeans were found to be high at 5.3 and 4.9%, respectively.
After heating, the RS1 levels of the rice and soybeans were significantly reduced to 0.4 and 2.4%, respectively. The total
nonstarch polysaccharide (NSP) content was not significantly different according to heat treatment, but the heat treatments
affected the amounts of water insoluble nonstarch polysaccharides (WISNSP) and water soluble nonstarch polysaccharides (WSNSP).
The level of WISNSP in the unheated samples was higher than the WSNSP of both samples; however, the WISNSP level showed a
reducing trend after heating. Also, total pentosan and water soluble pentosan contents showed similar trends with total NSP
and WSNSP. The hydrolysis indices (HI) of the unheated rice and soybeans were low (36.2 and 40.3%), while the heated group
had high levels (89.5 and 45.0%). Among the cooking methods, the highest kinetic constants (0.284 and 0.199) were found with
autoclaving for both rice and soybeans, followed by electric cooker (0.282 and 0.170), microwave oven (0.256 and 0.155), and
stone pot (0.238 and 0.167). Particularly, all soybean samples appeared to have lower starch hydrolysis kinetics than the
rice samples. The RS contents of the rice and soybeans were highest in the samples that were cooked in the stone pot, at 1.2
and 3.8%, respectively. 相似文献