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排序方式: 共有3146条查询结果,搜索用时 15 毫秒
151.
Lee TS Lee SW Seok WS Yoo MY Yoon JW Park BK Moon KD Oh DH 《Journal of food protection》2004,67(6):1123-1127
A total of 673 ready-to-eat vegetable samples were collected in Korea from 2001 to 2002 and analyzed for the presence of Yersinia spp. We analyzed biotypes, serotypes, and susceptibility to 12 antibiotics and tested for virulence genes of pathogenic Yersinia enterocolitica isolates by PCR assay. Among the samples, 27 (4.0%) were found to be contaminated with Yersinia spp. Among the 27 strains of Yersinia spp. isolates, 18 strains (66.7%) of Y. enterocolitica, 5 strains (18.5%) of Y. frederiksenii, 3 strains (11.1%) of Y. intermedia, and 1 strain (3.7%) of Y. kristensenii were identified. According to the serotypes of Y. enterocolitica isolates, O:3 (11.1%) and O:5 (11.1%) were the most predominant, followed by O:8 (5.6%) and others (72.2%). For biotypes of Y. enterocolitica isolates, 1A (77.8%) was the most predominant, followed by 3B (11.1%), 3 (5.6%), and 5A (5.6%). Also, an antibiotic susceptibility test showed that Y. enterocolitica isolates were very susceptible to the antibiotics tested but highly resistant to ampicillin (94%), cephalothin (100%), and carbenicillin (83%). PCR assays with specific primers derived from yst and ail genes of Y. enterocolitica were applied to confirm the presence of pathogenic Y. enterocolitica. Among the 18 strains of Y. enterocolitica isolates, only 3 strains (O:3/1A, UT/3B, and UT/1A isolated from Chinese cabbage, onion, and spinach, respectively) were shown to have a virulence gene. 相似文献
152.
A gene homologous to Saccharomyces cerevisiae MNN9 has been cloned and characterized in the methylotrophic yeast Hansenula polymorpha. This gene was cloned from a H. polymorpha genomic DNA library using the S. cerevisiae MNN9 gene as a probe. The H. polymorpha MNN9 homologue (HpMNN9) contained a 1062 bp open reading frame encoding a predicted protein of 354 amino acids. The deduced amino acid sequence showed 58% and 51% identity, respectively, with the S. cerevisiae and Candida albicans Mnn9 proteins. Disruption of HpMNN9 leads to phenotypic effects suggestive of cell wall defects, including detergent sensitivity and hygromycin B sensitivity. The hygromycin B sensitivity of S. cerevisiae mnn9 null mutant was complemented in the presence of the HpMNN9 gene. The DNA sequence of the H. polymorpha homologue has been submitted to GenBank with the Accession No. AF264786. 相似文献
153.
Synthesis and properties of click coupled graphene oxide sheets with three‐dimensional macromolecules 下载免费PDF全文
Sibdas Singha Mahapatra Madeshwaran Sekkarapatti Ramasamy Hye Jin Yoo Dong Hun Yi Jae Whan Cho 《应用聚合物科学杂志》2016,133(17)
A facile click chemistry approach to the functionalization of three‐dimensional hyperbranched polyurethane (HPU) to graphene oxide (GO) nanosheets is presented. HPU‐functionalized GO samples of various compositions were synthesized by reacting alkyne‐functionalized HPU with azide‐functionalized GO sheets. The morphological characterization of the HPU‐functionalized GO was performed using transmission electron microscopy and its chemical characterization was carried out using Fourier transform‐infrared spectroscopy, nuclear magnetic resonance spectroscopy, and X‐ray photoelectron spectroscopy. The graphene sheet surfaces were highly functionalized, leading to improved solubility in organic solvents, and consequently, enhanced mechanical, thermal, and thermoresponsive and photothermal shape memory properties. The strategy reported herein provides a very efficient method for regulating composite properties and producing high performance materials. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43358. 相似文献
154.
Polyurethane nanocomposites with click‐coupled nanodiamonds exhibiting enhanced mechanical and shape memory effects 下载免费PDF全文
Hye Jin Yoo Byung Hak Lee Sibdas Singha Mahapatra Cheol-Min Yang Jae Whan Cho 《应用聚合物科学杂志》2017,134(43)
Poly(?‐caprolactone)diol (PCL)–functionalized nanodiamonds (f‐NDs) were synthesized using a click chemistry reaction between the azide‐moiety PCL and alkyne‐moiety NDs and were incorporated into shape memory polyurethane (PU) at f‐ND concentrations of 0, 0.5, 1, and 2 wt % to produce high‐performance shape memory nanocomposites. The PU/f‐ND nanocomposites exhibited better shape recovery, shape recovery stress, and breaking stresses than pure PU. Shape recovery of greater than 95% was demonstrated for all the nanocomposites in the third cycle, and the shape recovery stresses increased significantly with the f‐ND content. These enhanced mechanical and shape recovery properties are ascribed to increased interactions between the f‐NDs and PU matrix due to incorporation of click‐coupled f‐NDs. The click‐coupled NDs can be used as nanofillers to enhance the mechanical and shape memory properties of polymers. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45465. 相似文献
155.
Determination of twisting angle of electrospun nanofiber bundle for continuous electrospinning system 下载免费PDF全文
Electrospinning continuously produced twisted nanofibers with a convergence coil and a rotating ring collector. The positively charged nozzle was used in the electrospinning process to deposit electrospun fibers of polyacrylonitrile onto a rotating ring collector. By withdrawing the electrospun fibers from the rotating ring collector, it was possible to spin the electrospun fibers yarn. In this study, theoretical approaches and numerical simulations were used to determine the twisting angle of the yarn. Using the equations developed in this study, we performed numerical simulations and compared the experimental results with the numerical simulation results. Mechanical properties of the fiber bundle were analyzed for twisting angle. It was confirmed the relationship among the winding drum, the ring collector, and flux of the fibers mass per time during electrospinning in the developed system. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45528. 相似文献
156.
157.
Shankara S. Kalanur Jaewoo Heo Il-Han Yoo Hyungtak Seo 《International Journal of Hydrogen Energy》2017,42(26):16901-16908
The ultrathin two-dimensional (2D) nanomaterials display unique properties owing to their ultrahigh specific surface area and strong quantum confinement of electrons in two dimensions. In this work, we fabricated a rapid gasochromic and electrical hydrogen sensing system containing 2D WO3 and Pd nanoparticles. 2D WO3 nano-plates (NP) are synthesized using sol–gel method and Pd nanoparticles are coated on WO3 by green photochemical deposition method. The sensor is fabricated by dispersing the 2D WO3/Pd composite on filter paper. In presence of hydrogen gas, 2D WO3/Pd composite produces visible change in color from brown to dark blue. With the fabricated sensor, as low as 0.1% H2 gas in air at room temperature can be easily detected using electrical sensing scheme whereas for higher concentration from 1 to 100%, eye readable gasochromic scheme can be utilized. The use of 2D WO3 decreased the response time in great deal compared to WO3 nanoparticles indicating the advantage of 2D structure in fabricating rapid response H2 sensors. The proposed method is simple and can be easily employed to large scale fabrication system for commercial applications. 相似文献
158.
Jin-Young Kim Min Jong Bae Shang Hyeun Park Taewon Jeong Sunjin Song Jeonghee Lee Intaek Han Ji Beom Yoo Donggeun Jung SeGi Yu 《Carbon》2012,50(1):170-174
Inorganic powder electroluminescence (IPEL) devices with the insertion of a carbon nanotube (CNT) layer were investigated to verify the effect of the increased local field produced by CNTs on electroluminescence (EL). To increase the field strength effectively, the CNTs were shortened using the cryogenic crushing method. IPEL devices with the insertion of a short CNT layer exhibited an increase in brightness and efficiency with increasing amount of CNTs. The local field enhancement by CNTs, further enlarged by the triple-junction, could increase the field strength applied to the phosphor, resulting in improved EL performance. In addition, short CNTs in an EL device can lead to field enhancement without an unintentional current flowing into the device. 相似文献
159.
Se‐Hee Jo Jeung Kun Kim Chang Geun Yoo Jin‐Il Kim Yoon‐Mo Koo Sunyong Mun 《加拿大化工杂志》2007,85(6):874-882
A ternary separation usually requires the use of two simulated moving bed (SMB) units in series. Since an increase in the number of SMB units leads to a significant increase in capital and operational costs, the use of a single SMB unit is preferred if its structure can be modified to treat a ternary separation. Such a modified single SMB unit has been typified by a five‐zone SMB or a two‐zone SMB so far. The separation performances‐of a five‐zone SMB and a two‐zone SMB are compared in this paper by using the ternary amino acid mixture as a model system. A five‐zone SMB is designed with the safety margin method while a two‐zone SMB is optimized using genetic algorithm. A five‐zone SMB based on the maximum allowable safety margin, although it may not guarantee the global optimum solution, results in much better separation performance than a two‐zone SMB at its global optimum state. 相似文献
160.
Seung-Joon Yoo Se-Il Lee Dong-Heui Kwak Kwang-Gil Kim Kyung-Jun Hwang Jae-Wook Lee Un-Yeon Hwang Hyung-Sang Park Jong-Ok Kim 《Korean Journal of Chemical Engineering》2008,25(5):1232-1238
Nanosized TiO2 sol synthesized by sol-gel method was successfully coated on the porous red clay tile (PRC tile) with micrometer sized pores.
PRC tile was first coated with a low-firing glaze (glaze-coated PRC tile) and then TiO2 sol was coated on the glaze layer. A low-fired glaze was prepared at various blending ratios with frit and feldspar, and
a blending ratio glazed at 700 °C was selected as an optimum condition. Then TiO2 sol synthesized from TTIP was dip-coated on the glazed layer (TiO2/glaze-coated PRC tile), and it was calcined again at 500 °C. Here, these optimum calcination temperatures were selected to
derive a strong bonding by a partial sintering between TiO2 sol particles and glaze layer. Photocatalytic activity on the TiO2/glaze-coated PRC tile was evaluated by the extent of photocatalytic degradation of methylene blue and acetaldehyde. Methylene
blue with the high concentration of 150 mg/l on the surface of TiO2/glaze-coated PRC tile was almost photodegraded within 5 hours under the condition of average UV intensity of 0.275 mW/cm2, while no photodegradation reaction of methylene blue occurred on the glaze-coated PRC tile without TiO2. Another photocatalytic activity was also evaluated by measuring the extent of photocatalytic degradation of gaseous acetaldehyde.
The photodegradation efficiency in TiO2/glaze-coated PRC tile showed about 77% photocatalytic degradation of acetaldehyde from 45,480 mg/l to 10,536 mg/l after the UV irradiation of 14 hours, but only about 16% in the case of the glaze-coated PRC tile. 相似文献