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871.
The plant Tanacetum coccineum (painted daisy) is closely related to Tanacetum cinerariifolium (pyrethrum daisy). However, T. cinerariifolium produces large amounts of pyrethrins, a class of natural insecticides, whereas T. coccineum produces much smaller amounts of these compounds. Thus, comparative genomic analysis is expected to contribute a great deal to investigating the differences in biological defense systems, including pyrethrin biosynthesis. Here, we elucidated the 9.4 Gb draft genome of T. coccineum, consisting of 2,836,647 scaffolds and 103,680 genes. Comparative analyses of the draft genome of T. coccineum and that of T. cinerariifolium, generated in our previous study, revealed distinct features of T. coccineum genes. While the T. coccineum genome contains more numerous ribosome-inactivating protein (RIP)-encoding genes, the number of higher-toxicity type-II RIP-encoding genes is larger in T. cinerariifolium. Furthermore, the number of histidine kinases encoded by the T. coccineum genome is smaller than that of T. cinerariifolium, suggesting a biological correlation with pyrethrin biosynthesis. Moreover, the flanking regions of pyrethrin biosynthesis-related genes are also distinct between these two plants. These results provide clues to the elucidation of species-specific biodefense systems, including the regulatory mechanisms underlying pyrethrin production.  相似文献   
872.
Experimental and epidemiological studies have demonstrated that fine particulate matter with a diameter of <2.5 μm (PM2.5) affects both the respiratory and immune systems. However, effective approaches to reduce PM2.5-induced hazardous effects have not been discovered yet. Streamer discharge is a category of plasma discharge in which high-speed electrons collide with oxygen and nitrogen molecules. Although streamer discharge can reportedly eliminate bacteria, molds, chemical substances, and allergens, its ability to decontaminate PM2.5 has not been previously demonstrated. The present study explored whether streamer discharge treatment could reduce PM2.5-induced inflammatory responses by employing an in vitro system. PM2.5 was collected under four conditions (Bangkok (Sep.–Dec.), Bangkok (Dec.–Mar.), Singapore, and Taipei). Airway epithelial cells and antigen-presenting cells exposed to non-treated PM2.5 in several conditions resulted in inflammatory responses. Streamer-discharged PM2.5 (Bangkok (Sep.–Dec.)) decreased the expression of interleukin (IL)-6 and IL-8 compared to non-treated PM2.5. Moreover, composition analysis demonstrated that streamer discharge reduced some compounds, such as endotoxins and polycyclic aromatic hydrocarbons, included in PM2.5 that can elicit inflammatory responses. Streamer discharge treatment can reduce endotoxins, polycyclic aromatic hydrocarbons, and the subsequent inflammatory responses induced by PM2.5 in vitro.  相似文献   
873.
The experimental result of the collection efficiency of the axial flow cyclone with the fixed guide vanes is lowerthan that with the tangential inlet pipe to the cyclone body due to the weak angular momentum transfer given byflowing through the guide vanes.However,one of the interesting points is the control of the collection efficiencydepended on the funnel shaped exit pipes.The collection efficiencies for these funnel shaped exit pipes aredepended on the Froude number.Then,in this paper,the experimental results of the pressure drop and also thecollection efficiency using the fly-ash particles and also the comparison of the calculated results of the collectionefficiency with the experimental results are described in detail.  相似文献   
874.
The influence of the sprayed layer thickness on rolling contact fatigue of a thermally sprayed alumina ceramics with a nominal composition of Al2O3–2.3 mass% TiO2 was investigated using a two-roller test machine under pure rolling contact condition with oil lubricant. The influence of undercoating of sprayed nickel-based alloy on rolling contact fatigue was also investigated. Thicknesses of the ceramics-sprayed layer of tested rollers were 0.2, 0.5 and 1.0 mm. The failure mode of sprayed rollers was spalling caused by subsurface cracking. In the case of sprayed rollers without undercoating, rolling contact fatigue strength of rollers with 0.2 mm thickness sprayed layer was the smallest. Rolling contact fatigue strength of sprayed roller with 0.2 mm thickness sprayed layer was improved by undercoating. In case the failure depth was small as compared with the thickness of sprayed layer, effect of undercoating on the rolling contact fatigue strength was little. The depths where the maximum values of subsurface shear stresses occurred, almost corresponded to the observed depth of spalling cracks.  相似文献   
875.
Several CVI-SiC/SiC composites were fabricated and the mechanical properties were investigated using unloading–reloading tensile tests. The composites were reinforced with a new Tyranno-SA fiber (2-D, plain-woven). Various carbon and SiC/C layers were deposited as fiber/matrix interlayers by the isothermal CVI process. The Tyranno-SA/SiC composites exhibited high proportional limit stress (∼120 MPa) and relatively small strain-to-failure. The tensile stress/strain curves exhibited features corresponding to strong interfacial shear and sliding resistance, and indicated failures of all the composites before matrix-cracking saturation was achieved. Fiber/matrix debonding and relatively short fiber pullouts were observed on the fracture surfaces. The ultimate tensile strength displayed an increasing trend with increasing carbon layer thickness up to 100 nm. Further improvement of the mechanical properties of Tyranno-SA/SiC composites is expected with more suitable interlayer structures.  相似文献   
876.
Sixty millimeter diameter single crystal of Nd3+ doped LiLuF4 was successfully grown by the Czochralski technique. No remarkable absorption due to unfavorable impurities was observed from optical absorption measurements in the vacuum ultra-violet spectral region. The high crystallinity and homogeneous luminescence characteristics were found from X-ray rocking curve and cathode-ray luminescence respectively. X-ray excited luminescence spectrum was measured and the significant 4f25d-4f3 luminescence at 182 nm was observed in the grown crystal. The pulse height spectrum was taken upon γ-ray irradiation. As a result, the grown crystals demonstrated sufficient response to the γ-ray showing the light yield of 420 ± 30 photons/MeV. The decay curve under α-ray irradiation was also investigated and described by two component decay kinetics which consists of the decay constants of 34 and 450 ns.  相似文献   
877.
The device parameter optimization for 1.48 mu m InGaAs/InGaAsP multiple quantum well laser diodes (MQW-LDs) was reported. Approximately 800- mu m-long MQW-LDs with five wells were found to give a moderately low driving current for 100 mW light output, as well as high maximum power. 250 mW maximum CW power was achieved for a long-cavity (1800 mu m) MQW LD. The MQW LDs were shown to operate stably at 100 mW output power as well.<>  相似文献   
878.
Four unknown peaks were detected in GC chromatograms during analysis of organophosphorus pesticide residues in foods. They were identified by using GC/MS as triethyl phosphate (TEP), tributyl phosphate (TBP), diphenyl 2-ethylhexyl phosphate (DPEHP) and N-ethyltoluenesulfoneamide (NETSA), which are used as plasticizers or flame retardants in food packaging. These chemical substances were detected in the range of tr. (below 0.01 microg/g) to 11 micro/g from 29 samples, and they were also detected in the packaging. It was supposed that they were transferred to the foods from the packaging. Furthermore, they were detected in some cereals and cereal products which contain fat and had been preserved for a long time.  相似文献   
879.
对于“直流电机+滚珠丝杠”驱动机构,摩擦是实现大行程具有纳米级分辨率点位控制的主要障碍.通过设计高增益PID控制器,可以抑制摩擦的影响并在大范围内实现纳米定位,只是系统的性能受到执行机构饱和的影响.通过将时间优化的Bang—Bang控制器与该PID控制器结合在一起构成变结构控制系统,使用PID闭环控制跟踪Bang—Bang控制下的理论减速轨迹,并实现最终定位,从而消除了饱和所造成的超调.实验和仿真结果显示,该系统可以在较大摩擦力和模型参数变化的情况下获得大范围无超调的纳米定住,并且响应时间最优.  相似文献   
880.
Binding activities and estrogenic/antiestrogenic activities of polycyclic aromatic hydrocarbons (PAHs) and hydroxylated PAHs (OHPAHs) having 2 to 6 rings were evaluated by competition assay and yeast two-hybrid assay expressing human estrogen receptor (hER), respectively. PAHs did not bind to hER and did not show any activity. On the other hand, OHPAHs bound to hER and several OHPAHs showed estrogenic or antiestrogenic activity. Relative estrogenic activity (REP E ) and antiestrogenic activity (REP AE ) were calculated from the values of E 2 and 4-hydroxytamoxyfen as positive controls, respectively. Several OHPAHs having 4 rings showed strongly estrogenic activity. 4-Hydroxybenzo[a]anthracene exhibited the strongest estrogenic activity (REP E = 7.5 × 10?3 ) followed by 3-hydroxybenzo[a]anthracene and 2-hydroxychrysene (REP E = 4.2 × 10?3 ). Several other 4-ring OHPAHs showed strongly antiestrogenic activity. 3-Hydroxybenzo[c]phenanthrene exhibited the strongest antiestrogenic activity (REP AE = 190) followed by 2-hydroxybenzo[c]phenanthrene (REP AE = 69) and 2- hydroxybenz [a]anthracene (REP AE = 0.42). The results suggested that there is a strong structure – activity relationship.  相似文献   
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