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51.
Won-Ho Lee Hyoun-Ee Kim Seong-Jai Cho 《Journal of the American Ceramic Society》1997,80(10):2737-2740
Microstructural evolution of gas-pressure-sintered Si3 N4 with Yb2 O3 as a sintering aid was observed. Microstructures typical for in situ toughened Si3 N4 , i.e., large elongated grains randomly distributed in a fine matrix, were observed. However, the size of the elongated grains near the surface was much larger than that at the center, resulting in two distinct regions: an inner region and an outer region. The smaller the amount of Yb2 O3 added, the larger the difference in the size of the elongated grains between the outer and inner regions. The difference between microstructures was diminished when 16 wt% Yb2 O3 was added. The microstructural change with Yb2 O3 content was attributed to the evaporation of Yb-containing liquid phase from the surface. 相似文献
52.
Hyeon Gyu Kim Yoo Hyun Park Yang Hyun Cho Myoung Ho Kim 《Journal of Intelligent Information Systems》2014,43(2):323-347
The join is an important operator in processing data streams. To produce outputs continuously over unbounded data streams, sliding windows are generally used to limit the scope of the join at a certain time. In the existing join algorithms, only a simple type of windows have been considered, which are updated whenever a new data item arrives on any input stream. On the other hand, a more common type of windows have not been addressed yet, whose intervals are updated periodically, i.e., slid by a predefined time interval. In this paper, we consider the time-slide windows in joining multiple data streams. The algorithm for the time-slide window join can vary according to (i) how frequently the join is evaluated and (ii) which structure is used for windowing. Regarding this, possible algorithms are discussed, and experimental results that compare their performances are provided in this paper. 相似文献
53.
The effects of estrogen-induced hyperlipidemia on plasma lipid peroxidation, fatty acid composition and osmotic fragility
of erythrocytes in chickens were studied. Young male chickens implanted with estrogen for three wk developed a marked hyperlipidemia.
Plasma levels of triglyceride, cholesterol and phospholipid were elevated 68-, four- and 24-fold, respectively, over controls.
There was also a two-fold increase in plasma lipid peroxidation measured by the thiobarbituric acid test. Vitamin E supplement
(1,000 IU/kg diet) reduced the plasma lipid peroxidation to the control level, but had no effect on the plasma lipid content.
Estrogen-induced hyperlipidemia resulted in changes in the fatty acid composition of membrane lipids of erythrocytes. The
major changes were an increase in oleic acid from 10.0% to 14.2% and a decrease in linoleic acid from 31.3% to 26.0%. The
erytrocytes with an altered membrane fatty acid composition were found to have an increased osmotic fragility. It was apparent
that there was a direct correlation between the oleic acid content and the osmotic fragility of erythrocytes. 相似文献
54.
Summary The cyclopolymerization of 1,8-diethynylnaphthalene(DEN) and its copolymerization with diethyl dipropargylmalonate(DEDPM) were carried out by various transition metal catalysts. MoCl5-based catalyst was found to be very effective and gave almost a quantitative polymer yield. The resulting dark-brown homopolymer(PDEN) was partially soluble in chloroform, tetrahydrofuran, and dimethyl sulfoxide, whereas copolymer (1:1) with number avaerage molecular weight
of 2.1x104 by GPC showed good solubility in those solvents. The structure of the polymers was analysed by IR, NMR, and UV-VIS spectroscopies. From the spectral and solubility data, it is proposed that cyclized products with the conjugated system are formed. Room temperature conductivities of the I2-doped homo and copolymer were found to be about 7.5x10-3 and 5.1x10-3 S/cm, respectively. 相似文献
55.
Sung-Yong Cho Seung-Shik Park Seung-Jai Kim Tae-Young Kim 《Korean Journal of Chemical Engineering》2006,23(4):638-644
Adsorption and desorption characteristics of the 2-methyl-4-chlorophenoxyacetic acid (MCPA) from aqueous solution onto the
activated carbon (GAC, F-400) were studied. Adsorption equilibrium capacities of the MCPA increased with decreasing pH and
temperature of the solution. Adsorption equilibrium of the MCPA could be represented by the Sips equation. The internal diffusion
coefficients were determined by comparing the experimental concentration decay curves with those predicted from surface diffusion
model and pore diffusion model. The adsorption model based on the linear driving force approximation (LDFA) was used for simulating
the adsorption behavior of the MCPA in a fixed bed. Over ninety five percent desorption of the MCPA could be obtained using
distilled water. 相似文献
56.
57.
Acicular goethite particles were synthesized by oxidation of an alkaline suspension of ferrous hydroxide using a bubble column with draft tubes of different diameters at a constant temperature of 40°C. The oxidation rate increased with decreasing draft tube diameter. The mean size based on the major axis of acicular particle decreased with increasing oxidation rate and decreasing draft tube diameter. The major axis was found to grow preferentially compared with the minor axis. The mean size of major axis was correlated well to the modified reaction rate defined as a product of the reaction rate per unit volume of the reactor multiplied by the ratio of the column diameter to the draft tube diameter, irrespective of the draft tube diameter. 相似文献
58.
In a previous study, CETP inhibitory peptide (3 kDa) was isolated from hog plasma. The peptide, synthesized chemically according
to the amino acid sequence of the 3-kDa peptide (designated P28), showed CETP inhibitory activity both in vitro and in vivo [Cho et al. (1998) Biochim. Biophys. Acta 1391, 133–144]. We report herein further unique features of P28 when it was associated with the cholesteryl ester (CE)-donor and-acceptor lipoproteins. Lipoprotein substrates with P28 present in both HDL (as a CE-donor) and LDL (as a CE-acceptor) served as poor substrates, with CE-transfer activity decreased
up to 60% compared to normal substrates without P28. P28 was found to be located in HDL fractions of hog plasma and showed the same electromobility as that visualized by PAGE on
7% polyacrylamide gel under nondenaturing conditions. Addition of apolipoprotein A-1 (apoA-1) or apoB antibody to a normal
CE-transfer mixture did not alter CE-transfer activity. However, addition of apoA-1 or −B antibody to a CETP-inhibition mixture
decreased the inhibitory activity of P28 by ca. 20%. Western blot analysis revealed that P28 was associated only with human and hog HDL among several lipoproteins purified from human, hog, and rabbit. CFTP-inhibition
assays with various lipoprotein substrates revealed that P28 exhibited substrate-specific inhibitory activity. The inhibitory activity of P28 was highly dependent on the type of lipoprotein substrate (whether CE-donor or-acceptor); P28 inhibited CE transfer from HDL to LDL, but it did not inhibit CE transfer from HDL to HDL. 相似文献
59.
Autoxidation of ethyl eicosapentaenoate and docosahexaenoate 总被引:2,自引:0,他引:2
Soon-Yeong Cho Kazuo Miyashita Teruo Miyazawa Kenshiro Fujimoto Takashi Kaneda 《Journal of the American Oil Chemists' Society》1987,64(6):876-879
The extent of oxidation of ethyl esters of eicosapentaenoic (EPA) and docosahexaenoic acids (DHA) was compared quantitatively
with that of ethyl linoleate (Lo) and ethyl linolenate (Ln) by oxygen uptake and formation of conjugated diene, hydroperoxide
and secondary oxidation products. EPA and DHA esters were oxidized rapidly even at 5 C in the dark after an induction period
of 3–4 days, while the induction periods of Ln and Lo esters were 20 days and more than 60 days, respectively. Oxygen uptake
of EPA and DHA esters after the induction period was 5.2 and 8.5 times faster than that of ethyl Ln, respectively. Hydroperoxides
of EPA and DHA esters are much less stable than those of ethyl Lo. The peroxide value is not necessarily a good indication
of oxidation in these polyenoic acids because a considerable amount of secondary products is formed at the early stage of
oxidation. Polymers were found to be major secondary products in these polyenoic esters. 相似文献
60.
Chul-Kun Cho Kil Sang Chang Timothy S. Cale 《Korean Journal of Chemical Engineering》1993,10(4):195-202
Magnetic crystallite thermometry has been used to measure the average nickel crystallite temperature in packed bed reactors
during ethane hydrogenolysis, an exothermic reaction. The technique is based on the temperature dependence of the magnetic
moment of dispersed nickel catalysts. Measurement of the average catalyst temperature is very useful for reactor control because
of its shorter time constant compared with exit fluid temperature. Bed temperature control based on the exit fluid temperature,
which has often been used as a control variable, is too slow to protect thermal runaway of the bed. The advantage of short
time constant by measuring the average catalyst temperature has been incorporated with enhanced feedback control system to
control the bed temperature and prevent the thermal runaway of the catalyst bed. An enhanced feedback control structure with
supervisory action performed better than the classical proportional-integral control in runaway prevention when the two control
schemes were compared with each other on the basis of the trippoint (incipient thermal runaway). 相似文献