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排序方式: 共有881条查询结果,搜索用时 15 毫秒
871.
The influence of bacterial inoculation methods on the efficacy of sanitizers against pathogens was examined. Dip and spot inoculation methods were employed in this study to evaluate the effectiveness of acidic electrolyzed water (AcEW) and chlorinated water (200 ppm free available chlorine) against Escherichia coli O157:H7 and Salmonella spp. Ten pieces of lettuce leaf (5 by 5 cm) were inoculated by each method then immersed in 1.5 liters of AcEW, chlorinated water, or sterile distilled water for 1 min with agitation (150 rpm) at room temperature. The outer (abaxial) and inner (adaxial) surfaces of the lettuce leaf were distinguished in the spot inoculation. Initial inoculated pathogen population was in the range 7.3 to 7.8 log CFU/g. Treatment with AcEW and chlorinated water resulted in a 1 log CFU/g or less reduction of E. coli O157:H7 and Salmonella populations inoculated with the dip method. Spot inoculation of the inner surface of the lettuce leaf with AcEW and chlorinated water reduced the number of E. coli O157:H7 and Salmonella by approximately 2.7 and 2.5 log CFU/g, respectively. Spot inoculation of the outer surface of the lettuce leaf with both sanitizers resulted in approximately 4.6 and 4.4 log CFU/g reductions of E. coli O157:H7 and Salmonella, respectively. The influence of inoculation population size was also examined. Each sanitizer could not completely eliminate the pathogens when E. coli O157:H7 and Salmonella cells inoculated on the lettuce were of low population size (10(3) to 10(4) CFU/g), regardless of the inoculation technique. 相似文献
872.
873.
Hotta A Saito Y Kyogoku K Kawabe Y Nishijima K Kamihira M Iijima S 《Journal of Bioscience and Bioengineering》2006,101(4):361-368
The production of retroviral vectors using a transient expression system has been improved to obtain a high-titer virus preparation that is difficult to produce using packaging cell lines due to the cytotoxic or cytostatic effect of transgenes. Here, we used one such production method, the so-called Q-vector system, and examined its potential for virus production. The Q-vector system could produce a similar level of viral vectors compared with the packaging cell system but the production seemed to depend on the size and nature of transgenes. In the process of investigation of the quantitative difference in viral components between the transient expression system and the packaging cell system, we found that the Q-vector system could express higher amounts of viral RNA and proteins compared with the packaging cell system. However, this did not lead to a higher virus titer compared with that produced by the packaging cell system. This suggests that retroviral RNA transcribed from the plasmid in the transient system seemed to be used mainly for translation and only some of the RNA molecules were packaged in viral particles. 相似文献
874.
Photocatalytic decolorization of azo-dye Orange II in water has been examined in an external UV light irradiation slurry photoreactor using zinc oxide (ZnO) as a semiconductor photocatalyst. The effects of process parameters such as light intensity, initial dye concentration, photocatalyst loading and initial solution pH on the decolorization rate of Orange II have been systematically investigated. A two-stage photocatalytic decolorization of Orange II, the first stage of fast decolorization rate and the subsequent second stage of rather slow decolorization rate, was found. The efficiency of decolorization of Orange II increased as initial Orange II concentration decreased and UV light intensity increased. There was the optimal ZnO concentration being around 1000 mg L(-1). The optimal pH was around 7.7, which was at the natural pH of the dye solution. The effect of aeration rate on the decolorization of Orange II has been also investigated and the enhancement of decolorization of Orange II with increasing aeration rate was found. By using a model for the light intensity profile in the external UV light irradiation slurry photoreactor, the simulation model for the decolorization of Orange II with ZnO photocatalyst has been developed. The proposed model in which the slow decolorization in the second stage as well as the initial fast decolorization is also taken into account could simulate the experimental results for UV light irradiation satisfactorily. The proposed simulation model in which the change of light intensity with time due to the decolorization of Orange II and the light scatter due to solid photocatalysts are considered will be very useful for practical engineering design of the slurry photoreactor of wastewater including textile dyes. 相似文献
875.
Tokunaga Y Lottermoser T Lee Y Kumai R Uchida M Arima T Tokura Y 《Nature materials》2006,5(12):937-941
Nanoscale self-organization of electrons is ubiquitously observed in correlated electron systems such as complex oxides of transition metals. The phenomenon of charge ordering (CO) or the formation of charge stripes, as observed for layered-structure cuprates and nickelates, is one such example. Among them, CO in manganites is closely tied to the orbital degree of freedom of 3d electrons, leading to staggered orbital ordering or the formation of orbital stripes in the layered structure. Here, we describe the phenomena of thermally induced rotation of the orbital stripes by 90( composite function) for bilayered manganite crystals with half hole doping, that is, a 1:1 ratio of Mn3+/Mn4+. The rotation of orbital stripes and the consequent CO coupled with the underlying lattice distortion were found to produce the charge-polarized state, as also shown by its optical second-harmonic generation activity. 相似文献
876.
A first-principle study of one-dimensional carbon atomic chain inserted single-wall carbon nanotubes
Using first principles calculations, we investigate the atomic and electronic structure of carbon nanowires (CNWs) as the carbon chain inserted into single wall carbon nanotubes (SWCNTs). It indicates that the (5,5) CNW system exhibits metallic character, however, the insertion of carbon chain can transit a semi-conducting (9,0) SWCNT into a metallic. 相似文献
877.
This article reports on the extraction behavior of heme proteins from an aqueous phase into ionic liquids (ILs) with dicyclohexano-18-crown-6 (DCH18C6), and the structure-function relationship of cytochrome c (Cyt-c) dissolved in ILs. We have found that DCH18C6 enables transfer of Lys-rich proteins into ILs via supramolecular complexation. The hydrophobicity and functional groups of ILs have a great influence on protein partitioning, and a hydroxyl group-containing IL with DCH18C6 is capable of the quantitative partitioning of Cyt-c. On the other hand, protein transfer using conventional organic solvents is negligibly small. UV-visible, CD, and resonance Raman spectroscopic characterizations indicate that the sixth ligand Met 80 in the heme group of the Cyt-c-DCH18C6 complex in IL is replaced by other amino acid residues of the peptide chain and that a non-natural, six-coordinate, low-spin ferric heme structure is induced in IL. Solubilization of Cyt-c in IL causes the environmental change of the heme vicinity of Cyt-c, which triggers the functional conversion of Cyt-c from an electron-transfer protein to peroxidase. The Cyt-c-DCH18C6 complex in IL provides remarkably high peroxidase activity compared with native Cyt-c, because of enhancement of the affinity for H2O2. 相似文献
878.
Tsunashi Kamo Yoshinori Tokuoka Masahisa Miyazaki 《Journal of chemical ecology》2012,38(12):1552-1560
The cowpea aphid Aphis craccivora that infests the black locust Robinia pseudoacacia shows toxicity to its predator, the multicolored Asian ladybird beetle, Harmonia axyridis. In contrast, the same aphid species that infests the common vetch, Vicia angustifolia, is suitable prey for H. axyridis larvae. Previously, it was reported that the toxicity of A. craccivora infesting R. pseudoacacia was due to canavanine and 2-aminoethanol, but there was some doubt about the toxicity of these compounds and their concentrations in the aphids. In the present study, we determined the concentrations of cyanamide, canavanine, and 2-aminoethanol in A. craccivora infesting the two host plants. In the extracts of A. craccivora that infested either of the host plants, canavanine was undetectable, and 2-aminoethanol was detected at the concentration of 3.0–4.0 μg/g fresh weight. Cyanamide was detected in the extract of A. craccivora that infested R. pseudoacacia (7.7 μg/g fresh weight) but not in that infesting V. angustifolia. The toxicity of canavanine, 2-aminoethanol, and cyanamide was evaluated against H. axyridis larvae in a bioassay by using an artificial diet containing these compounds at various concentrations. Cyanamide exhibited 10–100 times stronger toxicity than canavanine and 2-aminoethanol. These results indicate that the toxicity is at least partly due to cyanamide, which is present in the toxic A. craccivora that infests R. pseudoacacia but absent from the non-toxic A. craccivora that infests V. angustifolia. 相似文献
879.
Izumi Yoshizaki Takehiko Ishikawa Satoshi Adachi Etsuro Yokoyama Yoshinori Furukawa 《Microgravity science and technology》2012,24(4):245-253
An ice crystal growth experiment was performed on board the International Space Station. The experiment was repeated 134 times with various undercooling conditions. Dendrite crystal growth velocity and tip radius were precisely measured by using a newly developed software. The results are compared with those obtained previously on the ground as well as with those reported by Glicksman et al. for Succinonitrile (SCN). The plot of the dimensionless velocity V as a function of the dimensionless undercooling ?? under microgravity revealed values that were consistently lower than those obtained under 1-G which indicates that thermal convection was suppressed. The plot of the dimensionless radius R0 as a function of ?? showed a less scattered value. The stability factor ??* became close to that of SCN when it was calculated using the geometrical mean radius. 相似文献
880.
Wenxing Quan Hitoshi Niwa Naoto Ishikawa Yoshinori Kobayashi Yoshinori Kuno 《Computers in human behavior》2011,27(5):1527-1534
This paper presents our on-going work in developing service robots that provide assisted-care to the elderly in multi-party settings. In typical Japanese day-care facilities, multiple caregivers and visitors are co-present in the same room and any caregiver may provide assistance to any visitor. In order to effectively work in such settings, a robot should behave in a way that a person who needs assistance can easily initiate help from the robot. Based on findings from observations at several day-care facilities, we have developed a robot system that displays availability to multiple persons and then displays recipiency to an individual who initiates interaction with the robot. In this paper we detail this robot system and its experimental evaluation. 相似文献