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1.
于冀勇  陆善祥  陈辉 《现代化工》2007,27(Z1):60-64
简述了钒在催化裂化过程中对催化剂所产生的危害及污染机理,讨论了在污染中钒与有关因素的相互作用,对国外捕钒剂的应用情况进行了重点阐述,最后对国内捕钒剂的研究现状进行了分析.  相似文献   

2.
以草酸钒、偏钒酸盐、V2O5的水溶液作为捕钒催化剂的钒源,以分子筛结晶度的破坏程度做考察基准,对不同钒源,在同样水热老化条件下,取老化前后样品,做钒含量分析和相对结晶度测定.结果表明,钒危害和捕钒剂研究中,不同钒源的实验数据间不具有可比性,以计算钒含量做对比更要在相同的钒源基础上进行.  相似文献   

3.
通过改变老化处理气氛,研究其对催化裂化捕钒剂性能的影响。在水蒸汽和氮气气氛下,含有捕钒组分的催化剂与不含捕钒组分的催化剂催化活性接近,捕钒组分的捕钒效果不显著。在水蒸汽和空气气氛下,随着空气体积分数由0增加到50%,不含捕钒组分的催化剂微反活性由58%升高到69%,重油转化率由68. 82%升高到74. 02%;含有捕钒组分的催化剂微反活性由60%升高到73%,重油转化率由70. 04%升高到77. 10%,焦炭和干气选择性也优于不含捕钒组分样品,体现了捕钒组分的捕钒效果。通过控制老化气氛中SO2质量分数为0或0. 16%,考察SO2对捕钒组分的影响,结果表明,SO2对此捕钒组分的性能影响较小。  相似文献   

4.
脂肪酸系列辅集剂在废纸中的浮洗脱墨实验   总被引:1,自引:0,他引:1  
刘江涛 《湖北化工》2001,18(6):28-29
简介了脂肪酸捕集剂的捕集机理,选择了一系列脂肪酸配以TX-10作实验脱墨剂进行了相应了应用试验,结果不饱和脂肪酸捕集油墨性能优于饱和脂肪酸,C18 的脂肪酸优于C12、C16的脂肪酸。  相似文献   

5.
介绍了钒对流化催化裂化(FCC)催化剂的危害与机理,针对钒的特性研制出水溶性高效抗钒钝化剂.并刚实验验证了其极强的钝钒效果。  相似文献   

6.
氯气的突发泄漏事故会对周边环境产生极大危害,为减轻氯气泄漏对环境的影响,可采用捕消剂捕获氯气。分别采用活性炭捕消剂和钠基复配捕消剂对氯气进行捕消,考察了钠基复配捕消剂配比对氯气捕消效能的影响。结果表明,电石渣-氢氧化钠复配捕消剂、氢氧化钙-氢氧化钠复配捕消剂的氯气捕消效能优于活性炭捕消剂;在氢氧化钙∶氢氧化钠=3.0∶1(质量比)的条件下,氢氧化钙-氢氧化钠复配捕消剂平衡吸附3 min和10 min后的氯气吸附率分别高达97.7%和98.8%,且捕消稳定性好。  相似文献   

7.
脂肪酸系列捕集剂在废纸中的浮选脱墨实验   总被引:2,自引:0,他引:2  
简介了脂肪酸捕集剂的捕集机理 ,选择了一系列脂肪酸配以TX -10作实验脱墨剂进行了应用试验 ,结果不饱和脂肪酸捕集油墨性能优于饱和脂肪酸 ,C18的脂肪酸优于C12 、C16的脂肪酸  相似文献   

8.
阐述了硫化氢的理化性质、毒性危害、来源、其在生产中的分布以及硫化氢泄漏监测的方法。着重介绍了硫化氢泄漏处置的新技术——硫化氢捕消剂和硫化氢捕消器。通过对现场验证实验数据的分析证明了硫化氢捕消剂的有效性和实用性。  相似文献   

9.
陈鹏  许可  兰勇  张敏 《耐火材料》2000,34(4):220-221
针对攀钢提钒转炉的操作特点及钒渣特性,分析了炉衬的侵蚀机理及损毁原因,并为提高提钒转炉炉龄提供了可靠的对策,取得了显著的经济效益。  相似文献   

10.
重金属捕集剂对废水中铅捕集效果研究   总被引:6,自引:0,他引:6  
研究了几种重金属捕集剂对含铅废水的处理效果,讨论了反应时间、捕集剂加入量、pH值及多种重金属离子共存条件下各种捕集剂对铅处理效果的影响。实验结果表明,在反应时间为20min,捕集剂加入量为理论用量的1.2倍,pH值为2~6时处理效果较好,捕集效率在99%以上,且多种重金属离子共存条件下对捕集效果没有影响,处理后的废水能达到重金属国家排放标准。因此采用该方法优于传统处理方法,有很好的应用前景。  相似文献   

11.
The dentate gyrus (DG), an important part of the hippocampus, plays a significant role in learning, memory, and emotional behavior. Factors potentially influencing normal development of neurons and glial cells in the DG during its maturation can exert long-lasting effects on brain functions. Early life stress may modify maturation of the DG and induce lifelong alterations in its structure and functioning, underlying brain pathologies in adults. In this paper, maturation of neurons and glial cells (microglia and astrocytes) and the effects of early life events on maturation processes in the DG have been comprehensively reviewed. Early postnatal interventions affecting the DG eventually result in an altered number of granule neurons in the DG, ectopic location of neurons and changes in adult neurogenesis. Adverse events in early life provoke proinflammatory changes in hippocampal glia at cellular and molecular levels immediately after stress exposure. Later, the cellular changes may disappear, though alterations in gene expression pattern persist. Additional stressful events later in life contribute to manifestation of glial changes and behavioral deficits. Alterations in the maturation of neuronal and glial cells induced by early life stress are interdependent and influence the development of neural nets, thus predisposing the brain to the development of cognitive and psychiatric disorders.  相似文献   

12.
Crystal-bearing cells or idioblasts, which deposit calcium oxalate, are located in various tissues and organs of many plant species. The functional significance of their formation is currently unclear. Idioblasts in the leaf parenchyma and the development of crystal-bearing cells in the anther tissues of transgenic tomato plants (Solanum lycopersicon L.), expressing the heterologous FeSOD gene and which showed a decrease in fertility, were studied by transmission and scanning electron microscopy. The amount of calcium oxalate crystals was found to increase significantly in the transgenic plants compared to the wild type (WT) ones in idioblasts and crystal-bearing cells of the upper part of the anther. At the same time, changes in the size and shape of the crystals and their location in anther organs were noted. It seems that the interruption in the break of the anther stomium in transgenic plants was associated with the formation and cell death regulation of a specialized group of crystal-bearing cells. This disturbance caused an increase in the pool of these cells and their localization in the upper part of the anther, where rupture is initiated. Perturbations were also noted in the lower part of the anther in transgenic plants, where the amount of calcium oxalate crystals in crystal-bearing cells was reduced that was accompanied by disturbances in the morphology of pollen grains. Thus, the induction of the formation of crystal-bearing cells and calcium oxalate crystals can have multidirectional effects, contributing to the regulation of oxalate metabolism in the generative and vegetative organs and preventing fertility when the ROS balance changes, in particular, during oxidative stresses accompanying most abiotic and biotic environmental factors.  相似文献   

13.
王彦  左宁  姜媛媛  陈芳媛 《化工进展》2020,39(4):1539-1549
污泥生物炭中氮硫元素含量高,其氮硫行为和环境效应对全球气候变化的影响不容忽视。以往的研究中,研究者往往以富碳生物炭作为主要研究对象,关注碳对全球气候变化的行为和功效,而对氮硫元素的作用关注不够。本文从原始污泥基本性质到其热解过程,再到生物炭的老化,逐步对污泥生物炭整个生命周期内氮硫的行为及其环境效应研究进行综述,并对未来应注重开展的研究方向进行展望,为生物炭中氮硫元素固定、释放及与之关联的环境效应和温室气体排放控制研究提供理论基础。分析表明,污泥中氮元素含量普遍高于硫元素,且热解过程中氮比硫更容易转移至气相产物。氮硫元素随热解温度的增加,在三相产物中的分配都是炭中持续减少,油中先增后减,气中一直增加。高温(>800℃)条件下,气相中的氮含量高于固相,而硫元素则仍然主要存在于固相中。污泥生物炭老化及其环境效应研究表明,污泥生物炭氮硫元素与土壤的相互作用及其温室效应问题在今后的研究中应引起重视。  相似文献   

14.
The relationship of lacunocanalicular network structure and mechanoresponse has not been well studied. The lacunocanalicular structures differed in the compression and tension sides, in the regions, and in genders in wild-type femoral cortical bone. The overexpression of Sp7 in osteoblasts resulted in thin and porous cortical bone with increased osteoclasts and apoptotic osteocytes, and the number of canaliculi was half of that in the wild-type mice, leading to a markedly impaired lacunocanalicular network. To investigate the response to unloading, we performed tail suspension. Unloading reduced trabecular and cortical bone in the Sp7 transgenic mice due to reduced bone formation. Sost-positive osteocytes increased by unloading on the compression side, but not on the tension side of cortical bone in the wild-type femurs. However, these differential responses were lost in the Sp7 transgenic femurs. Serum Sost increased in the Sp7 transgenic mice, but not in the wild-type mice. Unloading reduced the Col1a1 and Bglap/Bglap2 expression in the Sp7 transgenic mice but not the wild-type mice. Thus, Sp7 transgenic mice with the impaired lacunocanalicular network induced Sost expression by unloading but lost the differential regulation in the compression and tension sides, and the mice failed to restore bone formation during unloading, implicating the relationship of lacunocanalicular network structure and the regulation of bone formation in mechanoresponse.  相似文献   

15.
Soil pH and Eh play an important role in reducing heavy metal solubility in paddy soils. To assess the effects of flooding and organic matter application on changes in Eh, pH and solubility of Cd, Ni and Zn in contaminated soils, a growth chamber experiment with rice plants(Oryza sativa L.) was conducted. Eh values decreased with flooding time in all three soils. The changes of Eh values were more negative in the tannery and alum shale contaminated soils and stabilized after 30 days of submergence. The Eh changes were not so large in the city sewage contaminated soil as in the other two soils. Soil pH increased with flooding time. During the 65 days of submergence, pH increase was about 2, 1 and 0.6units in the tannery, city sewage and alum shale soils, respectively. In all three soils, organic matter treated soil showed lower Eh and higher pH values compared to untreated soil. Concentration of Cd, Ni and Zn in soil solution decreased with flooding time. The solution concentration of Cd and Zn in the city sewage soil and of Ni in the tannery soil was higher than in the alum shale soil. The soluble metal concentration in all three soils was lower inorganic matter treated soils. Reduced solubility of metals in the organic matter treated soils was related to larger changes of Eh and pH values in these soils. Correlation coefficient calculations also showed that metal solubility decreased with decreased Eh and increased pH in the soil solution. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

16.
为了评价莠去津在玉米上使用的安全性,于2009―2010年在济南、焦作两地通过田间试验和气相色谱分析方法研究了莠去津在玉米和土壤中的消解动态和最终残留。莠去津在玉米植株和土壤中的降解行为均符合一级降解动力学方程,降解半衰期分别为3.6~4.2 d和6.5~12.9 d。土壤中莠去津消解速率焦作慢于济南,这可能与土壤中微生物菌群有关。莠去津在玉米植株、籽粒和土壤中的最终残留量均低于莠去津在玉米上的最大残留限量(MRL)0.05 mg/kg。本研究为制定该农药在玉米上的合理使用准则以及风险评估提供了科学依据。  相似文献   

17.
The evolutionary and ontogenetic development of the carotid body is still understudied. Research aimed at studying the comparative morphology of the organ at different periods in the individual development of various animal species should play a crucial role in understanding the physiology of the carotid body. However, despite more than two centuries of study, the human carotid body remains poorly understood. There are many knowledge gaps in particular related to the antenatal development of this structure. The aim of our work is to study the morphological and immunohistochemical characteristics of the human carotid body in the antenatal and postnatal periods of development. We investigated the human carotid bodies from 1 embryo, 20 fetuses and 13 adults of different ages using samples obtained at autopsy. Immunohistochemistry revealed expression of βIII-tubulin and tyrosine hydroxylase in the type I cells and nerve fibers at all periods of ontogenesis; synaptophysin and PGP9.5 in the type I cells in some of the antenatal cases and all of the postnatal cases; 200 kDa neurofilaments in nerve fibers in some of the antenatal cases and all of the postnatal cases; and GFAP and S100 in the type II cells and Schwann cells in some of the antenatal cases and all of the postnatal cases. A high level of tyrosine hydroxylase in the type I cells was a distinctive feature of the antenatal carotid bodies. On the contrary, in the type I cells of adults, the expression of tyrosine hydroxylase was significantly lower. Our data suggest that the human carotid body may perform an endocrine function in the antenatal period, while in the postnatal period of development, it loses this function and becomes a chemosensory organ.  相似文献   

18.
The ideal immunosuppressive regimen should provide for excellent immunosuppression with no side effects. Yet, current immunosuppressive therapy regimens commonly used in clinical applications fail to meet this criterion. One of the complications caused by immunosuppressive drugs is mineralization disorders in hard tissues. In this study, we evaluated the effects of three immunosuppressive therapies used after transplantation on the levels of potassium, iron, chromium, zinc, aluminum, sodium and molybdenum in the bones and teeth of female rats and their offspring. The study was conducted on 32 female Wistar rats, subjected to immunosuppressive regimens (cyclosporine A, mycophenolate mofetil and prednisone; tacrolimus, mycophenolate mofetil and prednisone; and cyclosporine A, everolimus and prednisone). The hard tissues of rats were analyzed using inductively coupled plasma optical emission spectrometry (ICP-OES, ICAP 7400 Duo, Thermo Scientific) equipped with a concentric nebulizer and a cyclonic spray chamber. All the immunosuppressive regimens included in the study affected the concentrations of the studied minerals in hard tissues of female rats and their offspring. The therapy based on cyclosporine A, everolimus and prednisone led to a decline in the levels of iron in bone, zinc in teeth, and molybdenum in the bone and teeth of mothers, while in the offspring, it caused a decline of bone potassium, with a decrease in iron and increase of molybdenum in teeth. Moreover, the regimen caused an increase in aluminum and chromium in the teeth and aluminum in the bones of the offspring, and consequently, it seems to be the therapy with the most negative impact on the mineral metabolism in hard tissues.  相似文献   

19.
Neuropathic pain (NeP) in humans is often a life-long condition with no effective therapy available. The higher incidence of female gender in NeP onset is worldwide reported, and although the cause is generally attributed to sex hormones, the actual mechanisms and the players involved are still unclear. Glial and immune cells take part in NeP development, and orchestrate the neuroimmune and inflammatory response, releasing pro-inflammatory factors with chemoattractant properties that activate resident immune cells and recruit immune cells from circulation. The neuro-immune crosstalk is a key contributor to pain hypersensitivity following peripheral nervous system injury. Our previous works showed that in spite of the fact that female mice had an earlier analgesic response than males following nerve lesion, the recovery from NeP was never complete, suggesting that this difference could occur in the very early stages after injury. To further investigate gender differences in immune and neuroimmune responses to NeP, we studied the main immune cells and mediators elicited both in plasma and sciatic nerves by peripheral nerve lesion. After injury, we found a different pattern of distribution of immune cell populations showing either a higher infiltration of T cells in nerves from females or a higher infiltration of macrophages in nerves from males. Moreover, in comparison to male mice, the levels of cytokines and chemokines were differently up- and down-regulated in blood and nerve lysates from female mice. Our study provides some novel insights for the understanding of gender-associated differences in the generation and perseveration of NeP as well as for the isolation of specific neurodegenerative mechanisms underlying NeP. The identification of gender-associated inflammatory profiles in neuropathy is of key importance for the development of differential biomarkers and gender-specific personalized medicine.  相似文献   

20.
Forms and nature of organic N in soil   总被引:3,自引:0,他引:3  
Most of the N in surface soils occurs in organic forms. The organic N in soil plays a key role in plant nutrition and soil fertility through its effects on microbial activity and nutrient availability. Typically, about one-third of the fertilizer N applied to temperate-zone soils is immobilized and retained in organic forms at the end of the growing season. A significant portion of this newly immobilized N is no more available to microorganisms and plants than the native humus N. Stabilization processes, probably involving polymerization of amino compounds and polyphenols, result in incorporation of N into humic substances with a concurrent reduction in N availability. This paper presents an account of the forms and nature of organic N in soil, emphasizing possible formation pathways, chemical characterization of humic substances through conventional and solid-state techniques, and the fate and composition of newly immobilized N in soil.  相似文献   

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