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11.
Nanoparticles (NPs) of TiO2 and ZnO are receiving increasing attention due to their widespread applications. To evaluate their toxicities to the earthworm Eisenia fetida (Savigny, 1826) in soil, artificial soil systems containing distilled water, 0.1, 0.5, 1.0 or 5.0 g kg−1 of NPs were prepared and earthworms were exposed for 7 days. Contents of Zn and Ti in earthworm, activities of antioxidant enzymes, DNA damage to earthworm, activity of cellulase and damage to mitochondria of gut cells were investigated after acute toxicity test. The results from response of the antioxidant system combined with DNA damage endpoint (comet assay) indicated that TiO2 and ZnO NPs could induce significant damage to earthworms when doses were greater than 1.0 g kg−1. We found that Ti and Zn, especially Zn, were bioaccumulated, and that mitochondria were damaged at the highest dose in soil (5.0 g kg−1). The activity of cellulase was significantly inhibited when organisms were exposed to 5.0 g kg−1 of ZnO NPs. Our study demonstrates that both TiO2 and ZnO NPs exert harmful effects to E. fetida when their levels are higher than 1.0 g kg−1 in soil and that toxicity of ZnO NPs was higher than TiO2. 相似文献
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通过对西南地区浅圆仓的隔热性能、气密性能、相配套的环流熏蒸系统以及通风系统性能的研究,总结出一些经济而有效的储粮方法,以指导储粮工作。 相似文献
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为了方便地控制机械密封实验台流体的温度,运用单片机作为主控机,设计了一套流体温度控制系统。主要介绍了机械密封流体温度控制的基本原理,并建立了机械密封流体温度控制的数学模型。系统软件的设计采用C语言,通过C51编译器将C程序转化为汇编语言程序。对该控制系统进行了仿真。设计结果表明,该方案是可行的并适用于其他温度控制系统,为机械密封实验台的设计提供了参考。 相似文献
16.
Antonious GF 《Pest management science》2002,58(1):85-91
The efficacy of esfenvalerate (84 g litre-1 EC; Asana XL) at 7.0 g AI ha-1 on broccoli was tested against the flea beetle, Phyllotreta cruciferae Goeze (Chrysomelidae: Coleoptera) and the imported cabbage worm, Pieris rapae L (Pieridae: Lepidoptera) under field conditions. Insect populations were monitored before and after treatment. Periodic sweep-net collections and examination of the leaves in treated and untreated broccoli plots revealed mean reductions of P cruciferae levels of nearly 98% 1 week post-application compared with untreated plots. The residual toxicity of esfenvalerate was also effective for 2 weeks in reducing population density of P rapae by 69% on broccoli leaves. The impact of esfenvalerate on feeding damage to broccoli leaves was established by counting the number of feeding holes made by P cruciferae on spring broccoli and P rapae on fall broccoli. As the leaf area ingested increased, a linear relationship was seen between the number of holes and number of insects. Results indicated that forage destruction by the two pests was significantly reduced by esfenvalerate application. Esfenvalerate was extracted from broccoli at 1 h and 1, 3, 7, 10, and 14 days post-application for residue analysis. Residues on spring broccoli were 12.2, 5.2 and 2.9 micrograms cm-2 on the leaves and 0.13, 0.05 and 0.02 microgram g-1 on the heads at 1 h, 1 and 3 days, respectively. Only trace levels (0.001 microgram g-1) were detected in/on the heads 14 days after spraying. On the basis of half-life (T1/2) values, persistence of esfenvalerate on spring broccoli leaves (T1/2 = 1 day) was shorter than on fall broccoli (T1/2 = 1.6 days). T1/2 values were 2.1 and 3.6 days on spring and fall broccoli heads, respectively. The implications of these residue levels on re-entry times into treated fields are discussed. 相似文献
17.
Smouldering wildfires propagate slowly through surface and subsurface organic layers of the forest ground and severely affect the soil, producing physical, chemical and biological changes. These effects are caused by the prolonged heating and the large loss of soil mass but are poorly documented in the literature. A series of smouldering experiments with boreal peat have been conducted under laboratory conditions to quantify these effects using small-scale samples. Peat samples of 100 mm by 100 mm in cross section and 50 mm in depth of different moisture were exposed to an external ignition source. Thermocouples placed throughout the sample bed measured the temperature evolution and tracked the peat ignition, intensity and spread of the smouldering front. The results show that moisture content controls peat ignition and that moisture below 125 ± 10% (in dry base) are required. The severity of the smouldering peat on the soil has been quantified in terms of temperature vs. residence time curves and mass loss. The measurements show temperatures in excess of 300 °C for residence times of 1 h leading to sterilization of the soil and mass loss in burnt layers above 90%. 相似文献
18.
在充分考虑机械臂伺服电机智能速度检测装置的结构和闭环运动过程控制的基础上,将智能交流接触器引入到了采摘机器人机械臂关节伺服电机的反馈控制中,并建立了PID闭环反馈调节回路,有效地提高了机械臂的控制精度。同时,将智能交流接触器以速度控制函数的形式嵌入到了PID控制环节,采用ADMAS和MatLab软件对机械臂的轨迹控制精度进行了测试,并利用Mat Lab软件计算得到了关节的控制变量,以Spline形式将变量导入到了ADMAS中对机械臂两关节进行控制。通过仿真得到了机械臂关节的输入和输出位移随时间变化曲线和机械臂末端的运动结果,结果表明:输入和输出的位移基本吻合,并且机械臂末端可以按照预定的圆环轨迹运动,从而验证了智能交流接触器PID控制的控制精度。 相似文献
19.
应用Ｃ语言编程实现架空送电线路（简称架空线路）导线机械计算,讨论了状态方程求解方法的选择。通过运行程序可输出弧垂表格和应力弧垂表格,提高了架空线路工程设计的速度和精度。 相似文献
20.
Wei-Ping Ma Shi-Ning Yin Jia-Peng Chen Xi-Cheng Geng Ming-Fei Liu Hai-Hua Li Ming Liu Hong-Bing Liu 《Marine drugs》2022,20(3)
Hematopoietic damage is a serious side effect of cytotoxic drugs, and agents promoting hematopoiesis are quite important for decreasing the death rate in cancer patients. In our previous work, we prepared the simulated digestive product of fucoidan from Sargassum fusiforme, DSFF, and found that DSFF could activate macrophages. However, more investigations are needed to further evaluate whether DSFF could promote hematopoiesis in the chemotherapy process. In this study, the protective effect of DSFF (1.8–7.2 mg/kg, i.p.) on cyclophosphamide-induced hematopoietic damage in mice and the underlying mechanisms were investigated. Our results show that DSFF could restore the numbers of white blood cells, neutrophils, and platelets in the peripheral blood, and could also retard bone marrow cell decrease in mice with cyclophosphamide-induced hematopoietic damage. UPLC/Q-Extraction Orbitrap/MS/MS-based lipidomics results reveal 16 potential lipid biomarkers in a serum that responded to hematopoietic damage in mice. Among them, PC (20:1/14:0) and SM (18:0/22:0) were the key lipid molecules through which DSFF exerted protective actions. In a validation experiment, DSFF (6.25–100 μg/mL) could also promote K562 cell proliferation and differentiation in vitro. The current findings indicated that DSFF could affect the blood cells and bone marrow cells in vivo and thus showed good potential and application value in alleviating the hematopoietic damage caused by cyclophosphamide. 相似文献