Processing and characterization of cobalt-containing SiC fiber

目前，先驱体转化法制备碳化硅（SiC）纤维的发展趋势是低成本化、高性能化以及多功能化。因此，将过渡金属元素引入SiC纤维当中，降低电阻率，提高磁性能，赋予纤维铁磁吸波性能，具有继承和发展功能化SiC纤维的重要意义。 本文发展了纳米钴溶胶的制备新路线，将其成功地引入到聚碳硅烷先驱体基体当中，制备出纳米钴粒子高度分散的Co-SiC纤维。具体过程是，首先将Co2(CO)8与低分子量的液态聚碳硅烷（LPCS）在十氢萘中分解反应形成稳定的钴溶胶；其次，将钴溶胶与固态纺丝级的聚碳硅烷（HPCS）互溶形成相容性良好的Co-PCS先驱体；最后经熔融纺丝、不熔化处理以及高温热解等工序制备出Co-SiC纤维。 ...At present, lower cost, higher performance and multifuction are acknowledged as the trend of development in the preparation of SiC fibers by precursor convertion method. Therefore, it will be much meaningful to carry on and develop the study on the functional SiC fiber by adding transition metal elements into them, which results in fiber being electromagnetic-wave-absorbing with a low electrical r...学位：理学硕士院系专业：材料学院_高分子化学与物理学号：2072010115010

剖宫产术后感染相关因素的回顾性分析

目的回顾性分析剖宫产术后感染的相关因素。方法随机抽取行剖宫产的产妇病历347份,以术后感染为结局指标,应用Logistic单因素与多因素分析剖宫产术后感染的独立高危因素,以及不同给药方案(包括给药品种、给药时间、给药时机)对术后感染的影响。结果阴道试产、术中出血量大、产后出血量大以及盆腔粘连是术后感染的独立高危因素(P 24 h组、给药时机为断脐后组与术前组,其术后感染的差异无统计学意义(P> 0. 05)。结论术中出血量大、阴道试产、盆腔粘连等高危因素以及预防性抗菌药物使用与剖宫产术后感染均相关

同步氢化/热缩聚法制备中间相沥青的工艺研究

系统地研究了在氢化剂量固定情况下,反应温度与时间对同步氢化/热缩聚法所制得的中间相沥青(MP)性质的影响,并制得了可纺MP。研究表明反应时间同为4h时,MP的软化点和不溶分含量随反应温度的提高而升高;偏光结果显示,低温产物为中间相小球和各向同性基质的混合物,高温产物为连续中间相。反应温度同为410℃时,MP软化点和不溶分含量均随反应时间的延长而显著提高,经历了从中间相小球到小球发生融并,最后形成了马赛克织构的中间相。纺丝性能测试表明,反应温度为410或420℃,反应4h制得的中间相沥青,可以熔融纺丝,经氧化和碳化后制得两组碳纤维

Effect of Flue-gas Cleaning Devices on Mercury Emission From Coal-fired Boiler

为研究燃煤锅炉烟气净化设施对汞排放特性的影响,采用Ontario-Hydro方法,对设有催化脱硝、静电除尘、海水脱硫的300MW燃煤锅炉排放烟气中汞的含量与形态进行分析,同时测定锅炉的煤、底渣、飞灰等固体样品以及脱硫塔前后、曝气之后海水样品中的汞含量。实验结果为:烟气中的气态汞占总汞的79.1%以上,脱硝催化剂对汞的价态具有强烈的转化作用,烟气中83.4%的气态Hg0被氧化成气态Hg2+;静电除尘对颗粒态汞的去除率几乎达到100%;在脱硫塔中,海水对烟气中汞的洗脱率高达73.6%,曝气后排放前的海水中含汞量是新鲜海水的5.5倍。研究表明锅炉烟气净化设施对汞的排放特性有着重要的影响。In order to study the effect of flue-gas cleaning devices on mercury emission from coal-fired boiler, Ontario-Hydro method had been applied to determine the mercury concentration and speciation in the flue-gas emitted from a 300MW coal-fired boiler, which was equipped with various pollution control devices, including selective catalyst reduction (SCR) De-NOx system, electrostatic precipitator (ESP), and flue-gas seawater De-SO2 system (FGD). Mercury concentration in raw coal, bottom ash and fly ash of the boiler, seawater at the inlet and outlet of SO2 absorption reactor and the drainage of aeration sink, were also analyzed. The results indicate that the percentage of gaseous mercury in total mercury discharged is more than 79.1%. De-NOx catalyst strongly affects the mercury speciation transformation, showing a conversion rate of 83.4% for Hg0 to Hg2+. The removal efficiency of particulate mercury by ESP is close to 100%. With seawater FGD, the removal efficiency of mercury is as high as 73.6%. The mercury concentration in the seawater of drainage from aeration sink is 5.5 times higher than that in fresh seawater. The study shows that the flue-gas cleaning devices in coal-fired power plant play an important role on mercury emission characterization

Preparation of silicon nitride fibers by pyrolysis nitridation of polycarbosilance

将PCS电子束交联丝在氨气氛中氮化热解、脱碳氨化,继在氮气氛中高温热引发缩合/转氨基反应,生成硅氮烷并最终形成氮化硅(SI3n4)纤维。所制备的SI3n4纤维白色透明,横截面和表面均光滑致密,无明显缺陷和孔洞。还研究了氮化热解的反应机理以及热解工艺对氮化硅(SI3n4)纤维结构和性能的影响。红外光谱和元素分析的结果显示,氮化热解脱碳彻底,SI3n4纤维C含量<1%;烧结温度提高,n含量随之增加,O含量则先增后减;烧结温度不超过1500℃,纤维为无定型。力学性能结果分析表明,随热解温度的提高,纤维力学性能先提后降,1300℃时达到最大值。氮化热解过程是采用nH3进行脱碳氨化,并在n2气氛下高温热引发缩合/转氨基反应产生硅氮烷并最终形成SI3n4的过程。In this work,PCS cured fibers were pyrolysis nitridation in the ammonia atmosphere for carbon removal and amination,and then condensation/nitridation reaction at high temperature in the nitrogen to produce Si3 N4 fibers.Results showed that as-prepared Si3 N4 fibers were colorless and transparent.What was more,the skin of the fiber was smooth and the cross section was rather dense without identifiable defects.This paper also discussed the mechanism of nitridation and the influence of pyrolysis conditions on the structure and properties of Si3 N4 fibers.The results of FT-IR spectra and elemental analysis showed that the carbon content was extremely low after amination and pyrolysis,which was less than 1%,while the nitrogen content increased with the elevated pyrolysis temperature,and the oxygen content first increased and then decreased with the elevated pyrolysis temperature.The fibers were amorphous when the pyrolysis temperature was less than 1500℃,while the tensile strength reached a maximum at 1300℃.The processes of pyrolysis nitridation were a process of decarburization and ammonification,and then condensation/nitridation at high temperature in the nitrogen,finally producing Si3N4fibers.国家自然科学基金面上资助项目(51002127;51072169

The influence of oxygen content on the structure and properties of Co-SiC fibers

系统研究了含钴聚碳硅烷交联丝的氧含量对所成含钴碳化硅(CO-SIC)纤维结构与性能的影响。研究结果显示,较之交联丝CO-PCS-AIr,CO-PCS-O2的氧含量较高,陶瓷产率较高,所成纤维的SICXOy相含量较高、β-SIC和COSI晶粒的增长速度较快,晶粒的尺寸较大,达到最大力学性能的烧结温度较低,电阻率也较低。该纤维电阻率在100~103Ω·CM之间可调,且具有一定的磁性,有望用作吸波纤维。In this work,it was systematically studied that how oxygen content of cured cobalt-containing polycarbosilance(PCS) fibers influences the structure and properties of cobalt-containing silicon carbide(Co-Si C) fibers.Compared to cured Co-PCS-air fibers,Co-PCS-O2 fibers have a higher oxygen content and higher ceramic yield.For Co-PCS-O2 fibers derived from cured Co-PCS-O2,lower pyrolysis temperature was required to reach maximum mechanical properties.And higher Si CxOycontent,higher growing speed and final sizes of β-Si C and Co Si grains and lower electrical conductivity were observed.Co-PCS-O2 fibers have a electrical conductivity controllable between 100-103Ω·cm and were magnetic to some degree,enabling this kind of fibers to have the potential to be used as wave-absorbing materials.国家自然科学基金面上资助项目(51002127;51072169

The influence of oxygen content on the structure and properties of silicon oxynitride(Si—O—N)fibers

令不同氧含量的聚碳硅烷氧化交联丝在高纯氨气中氮化热解、脱碳氨化,继而在高纯氮气下高温热引发缩合/转氨基反应,生成硅氧氮烷并最终形成氧含量不同的硅氧氮(SI—O—n)陶瓷纤维。Xrd、EPMA和TEM研究结果显示,所有元素在硅氮氧纤维中均匀分布,随着交联丝O含量增加,SI—O—n陶瓷纤维的O含量随之增加,力学性能下降,而陶瓷产率则先升后降。高氧时纤维陶瓷产率下降是因为在高温热解时发生了相分解。Xrd和TEM结果表明,氧含量不同的陶瓷纤维经1 500℃高温处理后,均仍为无定型。氧可能对氮化硅的结晶有抑制作用。In this work,PCS fibers,cured with different oxygen contents,were conducted by pyrolysis nitridation for carbon removal and amination in the ammonia atmosphere,and then through condensation/nitridation reaction at high temperature in the nitrogen atmosphere to produce silicon oxynitride fibers.Results of XRD, EPMA and TEM showed that,all of the elements in the ceramic fibers dispersed uniformly,and as the oxygen content in the cured fibers increased,it also increased in the ceramic fibers but with a drop in mechanical properties.However,the ceramic yield rose first and then fell because of the phase decomposition at high temperature.Indicated by the results of XRD and TEM,even after heat treatment at 1 500℃,ceramic fibers were still amorphous regardless of how much the oxygen content was.The oxygen maybe play a role like impurity in the fibers,which inhibites the crystallization of silicon nitride.国家自然科学基金面上资助项目(51002127;51072169

具有光热性能的碳龙配合物材料（英文）

金属有机化合物很少作为光热材料.报道一系列碳龙配合物的合成及其光热性能,将OsCl2（PPh3）3与有机多炔碳链反应获得金属杂戊搭炔,再与末端炔烃发生[2+2]环加成反应得到此类碳龙配合物--锇杂戊搭烯并环丁二烯.这些共轭的金属杂环化合物在紫外-可见区具有宽吸收并表现出优异的光热性能,有望成为一类新型的光热材料.Project supported by the National Natural Science Foundation of China(Nos.21302158,U1705254,21490573)~

具有光热性能的碳龙配合物材料（英文）

金属有机化合物很少作为光热材料。本文报道一系列碳龙配合物的合成及其光热性能。将OsCl2(PPh3)3与有机多炔碳链反应可获得金属杂戊搭炔,再与末端炔烃发生[2+2]环加成反应即可得到此类碳龙配合物——锇杂戊搭烯并环丁二烯。这些共轭的金属杂环化合物在紫外-可见区具有宽吸收并表现出优异的光热性能,有望成为一类新型的光热材料

可见光通信定位集成系统仿真研究

为了提升可见光通信（VLC）定位系统的频谱和功率利用率,文章提出了一种基于非对称限幅和直流偏置的光正交频分复用（ADO-OFDM）的VLC定位集成系统。该通信定位集成系统具有比基于非对称限幅的光正交频分复用（ACO-OFDM）的VLC定位集成系统更高的频谱利用率和比基于加直流偏置的光正交频分复用（DCO-OFDM）的VLC定位集成系统更高的功率利用率。同时,文章还提出了一种差分修正定位算法,所提算法较于传统的三边定位算法其具有更高的定位精度