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排序方式: 共有612条查询结果,搜索用时 31 毫秒
91.
In this study the deactivation of Pt/wire mesh and vanadia/monolith catalysts by aerosol particles of some inorganic salts (K2SO4, KCl and ZnCl2) with high or low melting points has been investigated. The aerosol particles may either diffuse within the matrix of the catalysts and block the mezzo and micro pores, or deposit on the outer surface of the catalysts and form a porous layer causing a mass transfer resistance that ultimately deactivates the catalysts. It has been observed that in both Pt/wire mesh and vanadia/monolith catalysts the deactivation effect of ZnCl2 was more pronouced compared to other salts. As an example, after 31 hours of exposure to ZnCl2, 10% of the catalysts activities was lost. This may be related to the ZnCl2 lower melting point in comparison with other poisons. These results are in agreement with the previous findings for deactivation of wire-mesh catalysts used for oxidation of volatile organic compounds (VOC) and CO by exposing the catalysts to the aerosols generated from inorganic salts.  相似文献   
92.
Synthesis of bio-based polyamide/acid-functionalized multiwalled carbon nanotube nanocomposites (PA/FCNT NCs) is reported in this investigation. New aliphatic–aromatic bio-based polyamide (PA) was synthesized through direct polycondensation reaction between bio-based diacid derived from a renewable resource; vanillin and diamine containing ether linkages. To obtain a homogeneous dispersion of multiwalled carbon nanotubes (MWCNTs) in the PA matrix, acid-functionalized MWCNTs (FCNTs) were used and PA nanocomposites with three different FCNT contents (1, 5 and 7?wt%) were prepared. The resulting NCs were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and thermogravimetric analysis (TGA).  相似文献   
93.
In this study, the photocatalytic degradation of Direct Red 23 (Scarlet F-4BS) was investigated in UV/TiO2 system. The effect of catalyst loading and pH on the reaction rate was ascertained and optimum conditions for maximum degradation were determined. The results obtained showed that acidic pH is proper for the photocatalytic removal of Direct Red 23. In addition, the effects of several cations (Cu2+, Al3+, Cr3+, and Sn4+) and anions (BiO3(-), SO4(2-), and CN(-)) and C2H5OH were examined in this photocatalytic process. On the order hand, three types of catalysts (Fe2O3, SnO2, and ZnO) were compared with TiO2. After 90 min reaction, the relative decomposition order established was UV/TiO2>UV/SnO2>UV/Fe2O3>UV/ZnO.  相似文献   
94.
The study investigated crossover of stress and strain in the workplace on a sample of 47 school principals and 183 teachers in Israeli elementary schools. The main goal of this study was to examine whether the crossover effect found among couples in the family also exists in the workplace. A 2nd aim of the study as to unravel the mechanisms that account for the crossover process. Using structural equation modeling, the authors found a significant crossover of job-induced tension but not of burnout from principals to teachers and vice versa. Being undermined by their principals elevated teachers' burnout and job-induced tension. This is the 1st study to demonstrate crossover of strain in the workplace and to discuss the implications of contagious job-induced tension in work environments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
95.
制革固体废弃物的吸附特性   总被引:6,自引:1,他引:5  
廖学品  张米娜  王茹  石碧 《化工学报》2004,55(12):2051-2059
分别研究了含铬废革屑和含单宁废革屑对染料和金属离子的吸附特性.结果表明:含铬废革屑对酸性染料和直接染料具有较强的吸附能力,而对碱性染料的吸附能力较弱;含单宁废革屑对Au3+、U6+、Th4+及Hg2+具有较强的吸附能力.含铬废革屑对染料的吸附平衡符合Langmuir方程;含单宁废革屑对Cu2+、U6+、Pb2+和Hg2+的吸附平衡符合Freundlich方程,而对Au3+及Th4+的吸附平衡符合Langmuir方程,因此含单宁废革屑对不同的金属离子可能具有不同的吸附机理.含铬废革屑对染料的吸附动力学以及含单宁废革屑对金属离子的吸附动力学均符合拟二级速度方程.含铬废革屑固定床对染料具有良好的吸附特性,固定床易再生和重复使用.含单宁废革屑固定床对Au3+的吸附量很大,但不易再生;而吸附其他金属离子后则容易再生,而且其吸附性能变化不大.  相似文献   
96.
An experimental study was conducted on the liquid‐liquid extraction of isobutyric acid by means of cumene from its aqueous solutions in an air‐operated impinging streams contactor (AOISC) with spray nozzles. Aqueous and organic streams may or may not contact one another inside the spray nozzles depending on the modes of operation. The overall volumetric mass transfer coefficient, KLa, determined enabled us to evaluate the performance capability of the contactor. The effects of air and solution flow rates, contactor length and diameter, impingement zone as well as modes of operation have been investigated. These experimental results verify the capability of the method of impinging streams in liquid‐liquid extraction.  相似文献   
97.
为确定组成复杂、浮油和高价金属离子含量高、酸性强的塔里木油田酸压返排液处理后能否顺利地配制压裂液,通过对返排液水质分析,提出了一套"过滤-化学沉淀-絮凝沉降-压裂液配制"的处理工艺。大量的浮油影响压裂液的溶胀及交联,滤布过滤可去除浮油与块状杂质组成的黏稠物;高价金属离子阻碍稠化剂分子的伸展,影响压裂液的携砂性能,碳酸钠可直接沉淀金属离子并中和残酸;简单处理之后需絮凝剂进一步絮凝处理,除去返排液中的小颗粒杂质。将处理后的水调节至中性或弱酸性直接配制成压裂液使用,可杜绝环境污染,缓解油田水资源匮乏问题。沉淀剂质量浓度为145g/L、絮凝剂质量浓度为1 000mg/L时,返排液中悬浮颗粒杂质的去除率达98%,水质平均粒径2.36μm。利用处理后的酸压返排液配制的压裂液挑挂性能良好,其流变性能和黏弹性能与清水直接配制的压裂液相差不大,均满足SY/T 6376-2008《压裂液通用技术条件》常规压裂液性能标准,适用于塔里木油田超深井高温高剪切要求。研究表明,酸压返排液重复利用配制压裂液的工艺是可行的。  相似文献   
98.
Interleukin (IL) 23 (p19/p40) plays a critical role in the pathogenesis of psoriasis and is upregulated in psoriasis skin lesions. In clinical practice, anti-IL-23Ap19 antibodies are highly effective against psoriasis. IL-39 (p19/ Epstein-Barr virus-induced (EBI) 3), a newly discovered cytokine in 2015, shares the p19 subunit with IL-23. Anti-IL-23Ap19 antibodies may bind to IL-39; also, the cytokine may contribute to the pathogenesis of psoriasis. To investigate IL23Ap19- and/or EBI3-including cytokines in psoriatic keratinocytes, we analyzed IL-23Ap19 and EBI3 expressions in psoriasis skin lesions, using immunohistochemistry and normal human epidermal keratinocytes (NHEKs) stimulated with inflammatory cytokines, using quantitative real-time polymerase chain reaction (RT-PCR), enzyme-linked immunosorbent assay (ELISA), and liquid chromatography-electrospray tandem mass spectrometry (LC-Ms/Ms). Immunohistochemical analysis showed that IL-23Ap19 and EBI3 expressions were upregulated in the psoriasis skin lesions. In vitro, these expressions were synergistically induced by the triple combination of tumor necrosis factor (TNF)-α, IL-17A, and interferon (IFN)-γ, and suppressed by dexamethasone, vitamin D3, and acitretin. In ELISA and LC-Ms/Ms analyses, keratinocyte-derived IL-23Ap19 and EBI3, but not heterodimeric forms, were detected with humanized anti-IL-23Ap19 monoclonal antibodies, tildrakizumab, and anti-EBI3 antibodies, respectively. Psoriatic keratinocytes may express IL-23Ap19 and EBI3 proteins in a monomer or homopolymer, such as homodimer or homotrimer.  相似文献   
99.
Yoo  Byoung-Wook  Kim  Bom  Joshi  Pankaj  Kwon  Sung-Ok  Kim  YeonJin  Oh  Jung-Sook  Kim  Jeongseon  Oh  Se-Young  Lim  Ji-Ae  Choi  Byung-Sun  Kim  Yu-Mi  Eom  Sang-Yong  Hong  Young-Seob  Sohn  Seok-Joon  Park  Kyung-Su  Pyo  Heesoo  Kim  Ho  Ha  Mina  Park  Jung-Duck  Kwon  Ho-Jang  Lee  Sang-Ah 《Food science and biotechnology》2018,27(4):1227-1237
Food Science and Biotechnology - This study was aimed to examine the association the blood/urinary concentration of toxic metal (Hg, Pb, and Cd) with children’s dietary patterns. This...  相似文献   
100.
为开发单环刺螠内脏中活性多糖成分,利用两步酶解法提取单环刺螠多糖,对其单糖组成、分子质量和连接方式等理化性质和结构特征进行研究,并通过体外清除脂质过氧化物实验对其活性进行初步评价。结果表明:采用木瓜蛋白酶和胰蛋白酶两步酶解后,单环刺螠内脏多糖得率为6.2%。单环刺螠内脏多糖(viscera polysaccharide,VP)分子质量约为4.1×103 u,从单糖组成可以看出,VP为组成复杂的类糖胺聚糖,主要含有葡萄糖(Glc),其次还含有氨基葡萄糖(GlcN)、甘露糖(Man)、半乳糖(Gal)和岩藻糖(Fuc),还含有少量的木糖(Xyl)、鼠李糖(Rha)、葡萄糖醛酸(GlcUA)和氨基半乳糖(GalN)。其单糖组成物质的量比为n(Man)∶n(GlcN)∶n(Rha)∶n(GlcUA)∶n(GalN)∶n(Glc)∶n(Gal)∶n(Xyl)∶n(Fuc)=1∶1.38∶0.87∶0.53∶0.52∶5.37∶1.38∶1.05∶2.40。VP还含有少量的硫酸基,含量为8.9%。葡萄糖作为VP中最主要的单糖,其连接方式主要为Glcp(1→、→4)-Glcp(1→、→4,6)-Glcp(1→和→3,6)-Glcp(1→。甘露糖主要含有Manp(1→、→2)-Manp(1→和→6)-Manp(1→连接方式。半乳糖含有Galp(1→和→4)-Galp(1→连接方式。而岩藻糖主要含有→4)-Fucp(1→,另外还有Fucp(1→、→3)-Fucp(1→和→3,4)-Fucp(1→连接方式。类糖胺聚糖具有丰富的生物活性,对VP进行初步体外抗氧化活性研究表明,其具有显著的脂质过氧化物清除活性,半数清除质量浓度为2.47 mg/mL。  相似文献   
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