Thermal- and Light-driven Metathesis Reactions Between Different Diselenides

Thermal- and light-driven diselenide metathesis reactions with different types of diselenides are investigated systematically. Their exchange reaction rates and equilibrium conversions are compared in the aspects of the different diselenide structures, activation conditions and solvents. As a result, the metathesis reactions between diselenide small molecules are demonstrated with high dynamic and sensitive features, which can be broadly tuned by varying the electron affinity and aromaticity of the diselenide substituents and external conditions(e.g., solvent, stimulus mode). The current work thus will not only advance our understanding on diselenide metathesis chemistry, but also promote concrete and impactful studies in selenium-containing materials.     

Development of the Self-doping Porous Carbon and Its Application in Supercapacitor Electrode

The massive discharge of biomass wastes not only causes waste of resources, but also pollutes the environment. Therefore, converting biomass wastes into carbon materials is an effective way to solve the above problems. Here, using biomass waste pig nails as raw materials and K₂CO₃ as chemical activators, the N-doped porous carbon(KPNC) is prepared by direct pyrolysis. As an electrode for supercapacitors, the electrochemical tests of KPNCs showed that they exhibited good electrochemical performance and excellent cycling stability. When the current density is 0.2 A/g, the specific capacitance is up to 344.6 F/g. Moreover, it still maintains 97.6% initial capacitance retention after 2000 cycles at a high current density of 5 A/g. Above exceptional electrochemical performances may be ascribed to an appropriate porous structure(S_micro/S_total=80.31%, V_micro/V_total=76.19%), high nitrogen contents(4.44%, atomic fraction), oxygen contents(9.13%, atomic fraction) as well as small internal resistance. The above experimental results show that the conversion of pig nails to porous carbon can reduce the waste of resources and alleviate environmental pollution.     

Surface Functionalization of PEO Nanofibers Using a TiO2 Suspension as Sheath Fluid in a Modified Coaxial Electrospinning Process

Convenient and integration fabrication process is a key issue for the application of functional nanofibers. A surface functionalization method was developed based on coaxial electrospinning to produce ultraviolet(UV) protection nanofibers. The titanium dioxide(TiO₂) nanoparticles suspension was delivered through the shell channel of the coaxial spinneret, by which the aggregation of TiO₂ nanoparticles was overcome and the distribution uniformity on the surface of polyethylene oxide(PEO) nanofiber was obtained. With the content of TiO₂ increasing from 0 to 3%(mass fraction), the average diameter of nanofibers increased from (380±30) nm to (480±100) nm. The surface functionalization can be realized during the electrospinning process to gain PEO/TiO₂ composite nanofibers directly. The uniform distribution of TiO₂ nanoparticles on the surface of nanofibers enhanced the UV absorption and resistance performance. The maximum UV protection factor(UPF) value of composite nanofibers reaches 2751. This work presented a novel surface-functionalized way for the preparation of composite nanofiber, which has great application potential in the field of micro/nano system integration fabrication.     

水体中TN/TP与藻类产生周期及产生量的关系

通过室内模拟的方法研究了用自来水作为试验水,当TN/TP在25∶1～4∶1的范围变化时,藻类的产生周期及产生量的变化情况.试验设置了25∶1,20∶1,15∶1,12∶1,10∶1,4∶1 6个比值.为了探讨温度对藻类产生的影响,分别在夏季和冬季做了对比试验.结果表明:当TN/TP在25∶1～12∶1的范围时,藻类的产生周期随TN/TP的减少而缩短,产生量随着TN/TP的减少而增加.在TN/TP为12∶1时藻类的产生周期最短,产生量最多.而TN/TP从12∶1～10∶1时,藻类的产生周期却随TN/TP的减少而增加,产生量随TN/TP的减少而减少.在TN/TP为4∶1时,没有产生藻类.季节对藻类的产生影响比较大.在夏季,藻类的产生周期较短,生产量较多;在冬季,藻类的产生周期较长,生产量相对较少.     

多径衰落信道下TCP协议的分析及改进

为了区分大尺度传播模型和多径衰落的小尺度模型在实际传播环境下的不同,针对无线信道多径衰落的特点,分析了TCP(Transmission Control Protocol)在多径衰落信道下的特性,提出了一种根据当前网络实际情况进行带宽估计而采取相应拥塞控制机制的TCP协议,并对不同TCP版本和改进后的协议进行了仿真分析。结果表明,改进后的协议能够根据网络的状况进行有效的拥塞控制,在既存有网络拥塞又有多径衰落导致丢包的情况下,其算法的吞吐率比TCP-Sack提高了约17.8%。     

新庄特稠油藏蒸汽吞吐井动态特征及水侵识别分析

河南新庄油田核桃园组的油藏是典型的边水驱动特稠油藏,在分析温度对分流方程的影响后,对该区蒸汽吞吐生产井的含水率变化规律进行了总结.根据油藏的实际地质特征,建立了数值模型,对所总结的含水率变化规律进行了模拟验证.在此基础上,结合存水量变化等参数,提出了一种综合判断地层水侵入规律的方法.实际的开采井动态分析证明了该判断方法的可行性,对类似的水侵特稠油藏的生产动态分析有借鉴作用.     

黔南石炭系层序地层格架中碳酸盐岩成岩作用研究

在三级层序地层格架内,从体系域及层序界面的角度对黔南石炭系碳酸盐岩的成岩作用进行了研究.结果表明,与LST有关的成岩作用主要为范围广泛的暴露溶蚀作用;与TST有关的成岩作用主要发育于海底成岩环境和混合水成岩环境,其中后者会随着海平面的不断上升而向大陆迁移;与HST有关的成岩作用主要包括发育于海底成岩环境的胶结作用及高位晚期的大气淡水成岩环境中的溶蚀、胶结和白云石化作用.与Ⅰ型层序界面有关的成岩作用主要有溶蚀作用、胶结作用和白云石化作用,成岩时间长、强度大,并且在黔南可进行区域对比;与Ⅱ型层序界面相关的成岩作用发育规模小,对碳酸盐岩的改造能力较弱.与HST有关的成岩作用及与Ⅰ型层序界面有关的成岩作用对碳酸盐岩储层的改造能力强,往往可形成厚层的白云岩及规模较大的溶蚀孔洞体系,因此,可以作为有利储层追踪对比及预测的有力地质依据之一.     

Tm3+/Yb3 :LiYF4单晶的高效近红外量子剪裁及其在光伏电池中的应用

采用改进的坩埚下降法成功地生长了Tm/Yb共掺氟化钇锂单晶. 该单晶体具有每吸收一个蓝色光子并能发射出2个1000 nm近红外光子的下转换发光效应. 测定了样品的激发光谱、发射光谱和荧光衰减曲线. 在465 nm蓝光激发下观察到由Yb³⁺：²F_5/2→²F_7/2能级跃迁所致的960～1050 nm 波段的发射带,此发光带源于Tm³ 对Yb³ 离子的能量下转换过程. 应用Inokuti-Hirayama模型,研究了晶体的能量转换过程,结果表明Tm³ 向Yb³ 的能量传递是一个电偶极子相互作用机制过程. 当Tm³ 与Yb³ 离子的掺杂浓度为0.49mol%与5.99mol%时,单晶的量子剪裁效率达到最大值167.5%.     

含各向异性左手材料的一维Thue-Mores准周期结构的反射带隙

采用传输矩阵法,研究了由各向同性右手材料和各向异性左手材料组成的Thue-Morse准周期结构的反射带隙,分析了入射角、偏振和晶格比例缩放因子对反射带隙的影响.结果表明该结构存在一个全方向反射带隙,该带隙的宽度由TE模的低频带边缘和TM模的高频带边缘决定.当在该结构中插入一层缺陷时,在全方向带隙中出现一条缺陷模.对TE模,缺陷模的位置受入射角的影响很弱,而对TM模,缺陷模的位置随入射角的增大,向高频方向移动.     

含Ti的HMS介孔材料催化剂及其对丙烯环氧化催化性能的研究

分别用水热合成法和气相四氯化钛(TiCl4)接枝法制备了Ti-HMS和Ti/HMS催化剂.表征结果表明,经过气相TiCl4接枝后的样品依然保持HMS(Hexagonal Mesoporous Silica,缩写为HMS)介孔材料特征,钛(Ti)物种主要以四配位的活性位形式存在.经过甲基接枝处理的催化材料,增加了表面的疏水性.丙烯环氧化反应结果表明,SN-Ti/HMS具有更高的催化性能.在2 500 h的稳定试验中,过氧化氢异丙苯(CHP)转化率大于99.0%,环氧丙烷(PO)选择性大于96.0%.研究和优化了环氧化反应工艺条件.采用浓度为30%的CHP为原料,CHP重量空速为1.0 h-1,床层温度为100℃,反应压力为3.0 MPa.