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41.
Polysaccharides extracted from Pleurotus eryngii were chemically modified by sulfation and the effects on the structural and biological properties of the polysaccharides were investigated as a function of the degree of sulfation. 13C NMR spectroscopy demonstrated that polysaccharides from P. eryngii were mainly composed of β-(1 → 3)-glucans with β-(1 → 6) branches. The structure of the sulfated polysaccharides was confirmed by FT-IR and their degree of substitution (DS) was determined to be 0.12–0.92. When P. eryngii polysaccharides were sulfated they were shown to be effective in inhibiting cancer cell growth in a dose-dependent way. Furthermore, their DPPH radical quenching effects were improved with increasing degree of sulfation. Thus, it seemed that the chemical modification of P. eryngii polysaccharides by sulfation effectively enhanced their potential biological properties. 相似文献
42.
A total of 115 desiccated food samples, including agricultural and marine products, were investigated for the presence of Cronobacter. Cronobacter species were characterized with biochemical tests. Antibiotic resistance was assessed with the disk diffusion method, and the molecular subtypes of Cronobacter isolates were identified using an automated repetitive sequence-based PCR (rep-PCR) system. A total of 18 (15.7%) Cronobacter strains were isolated from 115 desiccated food products. Fifteen Cronobacter isolates were C. sakazakii (13%), followed by 2 C. dublinensis (1.7%), and 1 C. universalis (0.9%). The most common antibiotic resistance of Cronobacter observed was against cephalothin (77.8%) followed by ampicillin (5.6%). With exception of 2 strains, all Cronobacter strains isolated from different sources were successfully differentiated by using the automated rep-PCR system, indicating that it can be used for the purpose of contamination or outbreak source tracking of the bacteria. 相似文献
43.
Young Jae Shin Do Hyeon Yang Mee Hye Oh Yeo Seong Yoon Jae Sup Shin 《Journal of Industrial and Engineering Chemistry》2009,15(2):238-242
Hard coatings were deposited on a polycarbonate plate using a sol–gel process with a melamine derivative, poly(vinyl alcohol) (PVA), and silicates and examined as potential substitutes for glass in cars. PVA was partially functionalized with (3-isocyanatopropyl)triethoxysilane, and the synthesized polymer was used to form a coating solution with methylated poly(melamine-co-formaldehyde), tetraethoxysilane, and methyltriethoxysilane. The coatings that contained both the melamine and silicate structures were deposited using a sol–gel process. The optimum conditions and formulation to obtain excellent physical properties of the coating were determined. Smooth coatings with the hardness of a 3H class pencil, excellent abrasion resistance and transparency were formed. 相似文献
44.
Orthorhombic‐pseudocubic phase transition and piezoelectric properties of (Na0.5K0.5)(Nb1−xSbx)‐SrZrO3 ceramics 下载免费PDF全文
Ku‐Tak Lee Dae‐Hyeon Kim Jong‐Seong Park Tae‐Gon Lee Sung‐Hoon Cho Su‐Jin Park Jong‐Yoon Kang Sahn Nahm 《Journal of the American Ceramic Society》2017,100(10):4827-4835
0.96(Na0.5K0.5)(Nb1?xSbx)‐0.04SrZrO3 ceramics with 0.0≤x≤0.06 were well sintered at 1060°C for 6 hours without a secondary phase. Orthorhombic‐tetragonal transition temperature (TO‐T) and Curie temperature (TC) decreased with the addition of Sb2O5. The decrease in TC was considerable compared to that in TO‐T, and thus the tetragonal phase zone disappeared when x exceeded 0.03. Therefore, a broad peak for orthorhombic‐pseudocubic transition as opposed to that for orthorhombic‐tetragonal transition appeared at 115°C‐78.2°C for specimens with 0.04≤x≤0.06. An orthorhombic structure was observed for specimens with x≤0.03. However, the polymorphic phase boundary structure containing orthorhombic and pseudocubic structures was formed for the specimens 0.04≤x≤0.06. Furthermore, a specimen with x=0.055 exhibited a large piezoelectric strain constant of 325 pC/N, indicating that the coexistence of orthorhombic and pseudocubic structures could improve the piezoelectric properties of (Na0.5K0.5)NbO3‐based lead‐free piezoelectric ceramics. 相似文献
45.
A heating process for obtaining free-standing carbon nanotube emitters is presented with the aim of improving field-emission properties from the screen-printed multiwalled carbon nanotube (MWCNT) films. Using an atmosphere with an optimum combination of nitrogen and air for heat treatment of CNT films, the CNT emitters can be made to protrude from the surface. This allows for a high emission current and the formation of very uniform emission sites without special surface treatment. The morphological change of the CNT film by this technique has eliminated additional processing steps, such as surface treatment which may result in secondary contamination and damage to the film. Despite its simplicity the process provides a high reproducibility in emission current density which makes the films suitable for practical applications. 相似文献
46.
47.
The preparation conditions of Ca-pectinate microparticles reinforced with liposome and hydroxypropylmethylcellulose (HPMC), including CaCl2 concentration (X1), HPMC concentration (X2), and hardening time (X3), were optimized for the sustained-release of catechin into simulated gastric and intestinal fluids using response surface methodology. The optimized values of X1, X2, and X3 were found to be 5.20%, 0.08%, and 12.63 min, respectively. The microparticles prepared according to the optimized conditions released about 50% of the entrapped catechin into simulated gastric fluid during 24-h incubation period, whereas almost complete catechin release was observed in simulated intestinal fluid after 8-h incubation. Antioxidant activity of catechin in rat plasma was more effectively maintained when the catechin-loaded microparticles were fed, compared to the case of feeding free catechin, indicating that the microparticles can protect catechin molecules in the rat model and release them in a sustained manner. 相似文献
48.
Bo Yeon Kim Chang-Boo Kim Seung Gwan Song Hyeon Gyu Beom Chongdu Cho 《Journal of Mechanical Science and Technology》2009,23(5):1396-1405
A finite thin circular beam element for the out-of-plane vibration analysis of curved beams is presented in this paper. Its
stiffness matrix and mass matrix are derived, respectively, from the strain energy and the kinetic energy by using the natural
shape functions derived from an integration of the differential equations in static equilibrium. The matrices are formulated
with respect to the local polar coordinate system or to the global Cartesian coordinate system in consideration of the effects
of shear deformation and rotary inertias. Some numerical examples are analyzed to confirm the validity of the element. It
is shown that this kind of finite element can describe quite efficiently and accurately the out-of-plane motion of thin curved
beams.
This paper was recommended for publication in revised form by Associate Editor Seockhyun Kim
Chang-Boo Kim received his B.S. degree in Mechanical Engineering from Seoul University, Korea in 1973. He then received his D.E.A., Dr.-Ing.
and Dr.-es-Science degrees from Nantes University, France in 1979, 1981 and 1984, respectively. Dr. Kim is currently a Professor
at the School of Mechanical Engineering at Inha University in Incheon, Korea. His research interests are in the area of vibrations,
structural dynamics, and MEMS. 相似文献
49.
The effect of CO2 laser irradiation on the refractive-index change in optical fibers is investigated by measuring the interference fringe shift formed by a long-period fiber grating pair. The refractive-index decrease on CO2 laser irradiation was due to relaxation of the residual stress, which was formed in optical fibers during the drawing process, and the refractive-index decrease was found to increase linearly with the drawing force. The effect of the CO2 laser output power on residual-stress relaxation, and fiber elongation was also studied. 相似文献
50.
Several types of detector, such as ultraviolet, infrared, visible light, differential pressure, flame rod, and others, are
employed to detect fire flame in power generation plants. However, these flame detectors have some performance problems. This
article describes the image-processing method of fire detection as well as neural network modeling. Nowadays, the image-processing
technique is broadly applied in industrial fields. The neural network model has strong adaptability and learning capability,
and is suitable for pattern classification. The Ulsan Steam Power Generation Plant in Korea was employed as the test field.
If this technique can be implemented, boilers will be able to operate more economically and effectively.
This work was presented, in part, at the 8th International Symposium on Artificial Life and Robotics, Oita, Japan, January
24#x2013;26, 2003. 相似文献