基于生态砖构建的新型河堤结构及位移分析

结合生态治理的要求,在分析国内外生态河堤的发展状况及相关的优缺点的基础上,提出了新型生态河堤,并通过ANSYS有限元软件对生态河堤的承载力及刚度进行有限元分析,对局部河堤结构进行了试验探究,并将有限元结果与试验结果进行对比,吻合情况较好。同时有限元结果也表明结构有较好的承载力、刚度、稳定性以及生态效果等,真正达到了人与自然的关系的和谐

沙眼衣原体致小鼠输卵管炎的病理研究

【: 目的】研究沙眼衣原体阴道内感染引起小鼠输卵管炎症的机理、病理改变。【方法】通过雌性小 鼠阴道内接种小鼠肺炎(MoPn)沙眼衣原体, 感染后不同时间观察小鼠输卵管病变情况, 并通过光镜、免疫组化 和电镜研究其病理改变。【结果】感染早期小鼠输卵管出现急性炎症改变, 病理表现为黏膜层水肿、脱落和坏 死; 电镜下, 在黏膜上皮细胞中找到沙眼衣原体。感染后期小鼠输卵管出现输卵管阻塞和积水, 病理表现为黏 膜皱襞减少, 黏膜层纤毛柱状上皮细胞成矮柱状, 顶部纤毛消失, 输卵管壁增厚、纤维组织增生和淋巴细胞浸 润, 免疫组化显示以CD4+ T 细胞浸润为主。【结论】阴道内沙眼衣原体感染可逆行感染引起输卵管炎症、粘 连、阻塞和积水; 其病理基础早期为黏膜层急性炎症改变和后期为输卵管壁增厚、纤维组织增生;局部以Th1 细胞介导为主的细胞免疫,导致了慢性输卵管炎的病理改变

NH3-SCR催化剂与纤维陶瓷膜复合方法与性能研究

氮氧化物（NOx）是一类重要的大气污染物，可以导致雾霾、光化学烟雾和酸雨等污染。目前我国氮氧化物的固定源排放仍然占据较大比例，在燃煤电厂大多实现超低排放情况下，非电行业的NOx排放控制成为现阶段主要攻坚环节之一。氨选择性催化还原技术（NH3-selective catalytic reduction，NH3-SCR）是控制NOx排放的主要技术，已在电厂锅炉中广泛应用。然而非电行业工业锅炉烟气成分复杂（经常同时含有二氧化硫、氮氧化物、颗粒物等组分）和温度窗口偏低等特点限制了NH3-SCR技术在该行业中的快速应用。目前非电行业工业锅炉烟气的治理技术是将单一控制模块串联使用，存在着流程长、占地面积大、投资运行费用高等问题。多组分协同治理与功能化耦合技术是解决上述问题的有效途径，其中气体处理技术与除尘模块的耦合是其研究重点之一。现有的除尘模块多集中在不耐高温的布袋和自重大的碳化硅陶瓷上，亟需轻质高强且耐高温的载体。本论文以高孔隙率（68%）和轻质高强（表观密度为0.625 g/cm3）的纤维陶瓷膜为载体，设计制备了NH3-SCR催化剂与除尘陶瓷膜功能耦合模块，重点研究了SCR催化剂的结构设计、负载方法以及催化性能的优化，目的在于研发低阻力、高催化效率的复合净化模块。研究内容和主要结果如下：（1）以轻质高强低阻的纤维陶瓷膜为基体，通过浸渍法，调节锰铈硝酸盐前驱体的负载量和摩尔比，经过煅烧得到锰铈系列的脱硝陶瓷膜块，并考察了负载量和锰铈摩尔比对催化性能的影响。锰铈摩尔比为6:4时得到的催化剂陶瓷膜脱硝性能最佳，可以在120-250 oC保持90%以上的脱硝效率，主要原因是丰富的Mn4+、表面活性氧和酸性位点有利于低温SCR反应。此外，NO转化率会随着氧浓度的增加而增加，随着空速的增加而降低。但是由于纤维陶瓷膜上催化组分含量较少，且锰系催化剂性能限制，所得到的膜催化剂耐硫性较差。（2）以三种商用分子筛ZSM-5、25beta（数字为硅铝比）和40beta为载体，以铁和锰硝酸盐为前驱体，通过浸渍法制备了Fe-Mn/分子筛催化剂，考察了分子筛载体对于脱硝性能的影响，将脱硝性能最好的Fe-Mn/25beta催化剂负载到陶瓷膜上，得到催化陶瓷膜。以分子筛为载体的催化剂适用脱硝温度窗口明显拓宽，其中Fe-Mn/25beta催化剂在220-450 oC可以将NO完全转化，主要原因是Fe和Mn更容易进入到beta分子筛的内部形成孤立的Fe(III)和Mn物种。更多的铁锰元素会在ZSM-5分子筛的表面形成氧化物颗粒，导致Fe-Mn/ZSM-5耐硫性变差。将Fe-Mn/25beta催化剂负载到陶瓷膜载体中，发现相比于粉末催化剂，低温活性稍有下降，高温活性稍有上升，耐硫性下降。（3）以自制的多孔氧化硅（MCM，比表面积为1188.7 m2/g）为载体，乙酰丙酮钒和钛酸四丁酯为前驱体，通过溶胶-凝胶方法制备比表面积改善的催化剂，将催化剂粉末以浆液涂覆的方式引入到陶瓷膜中，得到了钒钛系催化陶瓷膜。结果表明，5V2O5-20TiO2/MCM粉体（数字为相比于MCM的质量百分比）可以在250-450 oC内保持90%以上的NO脱除效率；且在SO2存在时，脱硝效率从90%下降到80%（T = 330 oC）；然而该系列的催化陶瓷膜的最高脱硝效率不到50%。（4）以正硅酸乙酯、钛酸四丁酯和乙酰丙酮氧钒为前驱体，采用一步溶胶-凝胶方法合成了钒钛硅系列复合氧化物；通过一步溶胶-凝胶（FC-sg）、两步溶胶凝胶（FC-2）和颗粒负载法（FC-p）三种负载方式将催化剂负载到陶瓷膜载体，对比研究了复合催化陶瓷膜的催化性能。结果表明，高硅含量可以提高催化剂粉末的比表面积，但是会降低钒物种的分散性，引起脱硝性能下降；高钒含量样品的脱硝温度窗口向低温区间移动。脱硝性能最好的配方为2V-90Ti10Si，可以在230-470 oC内达到90% 以上的NO转化率。从负载方式对脱硝性能的影响发现，在相同条件下的脱硝活性顺序为：FC-sg&asymp;FC-p&gt;FC-2；FC-2的效果最差，其原因是钒组分在制备过程中发生了迁移，在膜表面形成了聚集态的V2O5物种。;Nitrogen oxides (NOx) are kinds of the most important air pollutants, which can participate in the formation of haze, photochemical smog, acid rain, et al. The flue gas from stationary source still accounts for the majority of NOx in China. With the ultra-low emission in power industry, control of NOx from non-power industry is becoming crucial. Selective catalytic reduction of NOx by NH3 (NH3-SCR) is widely used in powder industry. However, the special temperature window and complexity of flue gas in non-power industry confines the use of NH3-SCR. The flue gas from industry boiler comprises particulates, sulfur oxide, and nitrogen oxides. In practical applications, the pollution control in flue gas is mostly completed by the combination of various separate units corresponding to one single pollutant. How to design the multifunctional units in which yielding the coupled effects of de-NOx and dust precipitation becomes more interesting. The dust precipitation modules comprise bag filters that intolerance to high temperature and SiC filter with large self-weight. Therefore, a support with light weight and high dust precipitation efficiency is needed. In this thesis, the fibrous ceramic membrane (porosity-68%, apparent density-0.625 g/cm3) with high strength were used as support, and loaded with NH3-SCR catalysts in order to obtain catalytic membrane with low pressure drop and high de-NOx efficiency. The catalysts composition, microstructure, depositing method and the catalytic performance were investigated. The main research content and conclusions were as follows.(1) Using manganese and cerium nitrates as raw materials, Mn-Ce oxides catalysts were loaded on fibrous ceramic membrane with light weight, high strength and low pressure drop, in order to obtain catalytic ceramic membrane. The effects of loading weights and molar ratios of Mn/Ce on catalytic performance were investigated. The catalytic membrane with Mn/Ce molar ratio of 6/4 performed a best de-NOx performance, with more than 90% de-NOx efficiency in the temperature range of 120-250 oC; mainly because the abundance of Mn4+, surface oxygen species, and acid sites facilitate the low temperature SCR. The de-NOx efficiency of catalytic membrane increased with oxygen concentration, and decreased with space velocity. Due to a small amount of catalysts on membrane, and the poor anti-sulfur characteristics of manganese catalysts, the catalytic performance of Mn-Ce based membrane decreased when introducing SO2 in flue gas. (2) The Fe-Mn/zeolite catalysts were prepared by employing ZSM-5, 25beta and 40beta as supports and iron nitrates, manganese nitrates as precursors through a co-precipitation method. The influence of support on de-NOx and its mechanism were analyzed. Fe-Mn/25beta catalyst showed the best catalytic performance, and it was loaded onto the membrane to obtain catalytic membrane with good low temperature SCR and anti-sulfur performance. Fe-Mn/25beta can obtain 100% NO conversion in a wide temperature window of 220-450 oC, mainly beacause Fe and Mn elements can easily enter the matrix of beta zeolites. However, more metal oxides aggregated on the surface of ZSM-5, leading to poor anti-sulfur performance of Fe-Mn/ZSM-5. Fe-Mn/25beta powder were loaded onto ceramic membrane, and compared with powder catalysts, its high temperature performance increased, low temperature and anti-sulfur performance decreased.(3) The vanadium-titanium composites with large specific surface area were obtained by employing porous silica (MCM, BET = 1188.7 m2/g) as supports and vanadyl acetylacetonate, tetrabutyl titanate as precursors through a sol-gel route. The powder catalysts were then loaded onto ceramic membrane to obtain vanadium titanium based catalytic membrane. It was shown that 5V2O5-20TiO2/MCM (the number denoted as loading weight of V2O5 and TiO2 on MCM) performed more than 90% NO conversion in 250-450 oC. The NO conversion decreased from 90% to 80% when introducing SO2 into flue gas (T = 330 oC). However, when loading the powder onto ceramic membrane, the NO conversion of catalytic membrane decreased to less than 50%. (4) The vanadium-titanium-silicon porous composites were synthesized by using tetraethyl orthosilicate, tetrabutyl titanate and vanadyl acetyacetonate as raw materials through a sol-gel route. The catalysts with best SCR performance were loaded onto ceramic membrane by one-step sol-gel method (FC-sg), two-step sol-gel method (FC-2) and particle loading method (FC-p) to obtain catalytic membrane. The specific area of composites was increased with the contents of silica; however, more silica would lead to worse dispersion of vanadium oxide, thus leading to NO conversion decrease. The de-NOx temperature window moved to low temperature range with high vanadium loading. The catalysts with wide temperature window (230-470 oC with more than 90% NO conversion) was 2V-90Ti10Si. The influence of loading methods were investigated, and it was shown the catalytic performance followed FC-sg&asymp;FC-p&gt;FC-2. The FC-2 sample showed the worst catalytic performance, mainly because the vanadium species removed to membrane surface, leading to aggregated V2O5 species.&nbsp;</p

低温非钒基NH_3选择性催化还原催化剂的技术需求和研究进展

低温脱硝技术对于氮氧化物(NOX)的脱除意义深远,而NH3选择性催化还原(NH3-SCR)NO技术不仅在燃煤工厂里有应用,也在移动源的NOX的脱除上有应用的潜能。在低温NH3-SCR技术领域,很多非钒基的催化剂材料因其优异的催化性能受到重视。简述了低温SCR技术在能源、水泥、冶金行业的技术需求,并着重介绍了各种催化剂的SCR活性、不同催化剂的催化机制和抗SO2、H2O性能。并由此得出未来工业脱硝对催化剂的高SCR催化活性、高的N2选择性以及良好的抗SO2和H2O性能的要求

一种Polar码删余方法及其在图像传输中的应用

文章提出一种基于权值的Polar码删余方法,并将其应用于高斯信道下的图像传输中。该方法对图像灰度值权值相同的比特进行Polar码编码,并根据图像灰度值权值的大小确定删余位数,权值大的二进制序列编码后删余位数少,权值小的删余位数多。用峰值信噪比（PSNR）来衡量重建图像的性能,仿真结果表明,在信噪比为6dB的高斯信道下的图像传输中,所提方法得到的PSNR相比于固定Polar码删余法提高了18dB,相比于随机删余法提高了11dB。信噪比越大,改进的删余Polar码的性能优于固定删余码率的Polar码和随机删余法的性能越明显

低温非钒基NH_3选择性催化还原催化剂的技术需求和研究进展

低温脱硝技术对于氮氧化物（NOX）的脱除意义深远,而NH3选择性催化还原（NH3-SCR）NO技术不仅在燃煤工厂里有应用,也在移动源的NOX的脱除上有应用的潜能。在低温NH3-SCR技术领域,很多非钒基的催化剂材料因其优异的催化性能受到重视。简述了低温SCR技术在能源、水泥、冶金行业的技术需求,并着重介绍了各种催化剂的SCR活性、不同催化剂的催化机制和抗SO2、H2O性能。并由此得出未来工业脱硝对催化剂的高SCR催化活性、高的N2选择性以及良好的抗SO2和H2O性能的要求

低温非钒基NH_3选择性催化还原催化剂的技术需求和研究进展

低温脱硝技术对于氮氧化物（NOX）的脱除意义深远,而NH3选择性催化还原（NH3-SCR）NO技术不仅在燃煤工厂里有应用,也在移动源的NOX的脱除上有应用的潜能。在低温NH3-SCR技术领域,很多非钒基的催化剂材料因其优异的催化性能受到重视。简述了低温SCR技术在能源、水泥、冶金行业的技术需求,并着重介绍了各种催化剂的SCR活性、不同催化剂的催化机制和抗SO2、H2O性能。并由此得出未来工业脱硝对催化剂的高SCR催化活性、高的N2选择性以及良好的抗SO2和H2O性能的要求

过渡金属、Zr、Ce三元SCR催化剂的制备和性能

制备了由过渡金属M(M=Cr、Mn、V、Fe、Cu、Co)与Zr、Ce氧化物组成的三元选择性催化还原(SCR)催化剂,用低温氮吸附(BET)、X射线衍射分析(XRD)、X射线光电子能谱(XPS)、氨-程序升温脱附(NH3-TPD)、氢-程序升温还原(H2-TPR)等手段表征了样品的比表面和孔结构、晶体结构、元素价态、酸性位类型以及氧化还原能力,研究了催化剂的性能。结果表明,MnZr-Ce三元催化剂的低温(250℃)活性较差;Cr-Zr-Ce三元催化剂在低温和高温(100-300℃)下性能均比较稳定,V-Zr-Ce三元催化剂在低温(&lt;200℃)下性能较差,但是其...</p

基于多体系统理论面齿轮数控磨床综合误差建模及分析

运用多体系统运动学理论及Denavit-Hartenberg齐次坐标变换,分析了面齿轮数控磨床几何误差和热误差。根据面齿轮啮合原理及磨削误差产生机理,建立了包含几何误差和热误差的面齿轮数控磨削加工机床综合误差数学模型。基于小误差假设,运用matlab软件,得到了磨床6个自由度的误差表达式。并对砂轮主轴运动所产生的6个误差与6个自由度之间的关系进行了分析和验证。对面齿轮加工精度的提高和机床误差建模提供了依据

阻断内侧前额叶皮质TrkB受体对大鼠认知和海马BDNF表达的影响

脑源性神经营养因子（brain-derived neurotrophic factor,BDNF）广泛参与了个体学习和记忆等认知功能,通过与其酪氨酸激酶受体（tyrosine kinase,TrkB）特异性结合,实现其多种神经生化功能。本研究观察了TrkB受体阻断剂ANA-12的慢性内侧前额叶皮质（medial prefrontal cortex,mPFC）注射对大鼠旷场行为、Morris水迷宫空间学习和逆反学习的影响。研究结果表明,mPFC的慢性BDNF阻断显著降低了大鼠在逆反学习测试中的逃离潜伏期和运动距离即增强了大鼠的逆反学习能力,但不影响其旷场行为和水迷宫空间学习能力。同时,慢性阻断mPFC-TrkB受体也并未导致大鼠海马BDNF蛋白含量的显著改变。这些结果提示,对于大鼠的Morris水迷宫空间学习和逆反学习,mPFC-BDNF主要在逆反学习调节中发挥重要作用。这对于进一步探索海马和mPFC在调节个体认知功能中各自的作用及其潜在的相互关系提供了有力的证据和支持