石墨烯辐照损伤及力学性能研究

石墨烯的加工和掺杂是其工程应用和性能开发的重要手段,离子辐照技术是实现上述目的的有效途径.利用分子动力学方法建立了硅离子辐照石墨烯和辐照后拉伸的数值模型.考虑辐照剂量、辐照能量和辐照角度这3个主要影响因素,研究了不同辐照条件下石墨烯的缺陷类型和数量,并分析了在辐照剂量影响下的拉伸破坏.结果表明:当辐照能量较小时,入射粒子会吸附在石墨烯表面.随着辐照能量的增大,入射粒子会穿透石墨烯而形成缺陷,当辐照能量到达一定值时,再无吸附原子.随着辐照剂量的增加,溅射原子和缺陷数目均增多,且缺陷类型以空位缺陷为主,其拉伸力学性能随着缺陷数量的增加而减小,二者近似成线性关系.辐照后石墨烯的拉伸破坏机理与完美石墨烯的有所不同,应力强化阶段明显缩短,缺陷带决定其起裂位置和断裂走向.      

连通容器泄爆过程的影响因素

以甲烷/空气混合物为研究对象,开展了连通容器气体泄爆影响因素的实验研究。结果表明:连通容器泄爆片泄爆时,随着破膜压力和量纲一泄压比的减小,大、小球容器的最大泄爆压力均增大;在等量纲一泄压比条件下,随着连接管道长度的增加,传爆容器的最大泄爆压力增大。连通容器无膜泄爆时,大球点火条件下,无论管长如何,起爆容器和传爆容器均比单个容器最大泄爆压力大。小球点火条件下,当管道长度为0.45 m时,起爆容器和传爆容器的最大泄爆压力均小于单个容器。连通容器无膜泄爆且量纲一泄压比相同时,当管道长度为0.45 m时,大、小容器内的最大泄爆压力基本相等;当管道长度为2.45 m时,大容器点火时,传爆容器最大爆炸压力大于起爆容器,但小容器点火时,起爆容器最大泄爆压力大于传爆容器;当管道长度为4.45和6.45 m时,传爆容器最大泄爆压力均大于起爆容器。     

负载钯纳米粒子聚电解质空心微球的制备及其还原对硝基苯酚的催化活性

用表面引发原子转移自由基聚合法(SI-ATRP)在二氧化硅纳米粒子表面接枝聚碘化甲基丙烯酸三甲基胺基乙酯(PMETAI),原位还原静电吸附的PdCl62-后刻蚀除去二氧化硅模板,成功制备了Pd纳米粒子复合聚电解质空心微球(air@PMETAI@Pd)。 用透射电子显微镜(TEM)、红外光谱仪(FTIR)、能谱仪(EDX)、热重分析仪(TGA)等技术手段对所制备的空心微球进行表征。 结果表明,Pd纳米粒子均匀负载在聚电解质微球上,其直径约为(1.5±0.2) nm。 将负载Pd纳米粒子的微球作为催化剂应用于硼氢化钠还原4-硝基苯酚反应,显示出很好的催化效果且具有较好的回收利用性。     

直线变压器驱动源磁芯能量传递效率

磁芯是直线变压器驱动源(LTD)的关键部件之一,起着初、次级能量传递和次级电压感应叠加的作用,磁芯的能量传递效率对LTD系统的效率、体积和重量影响显著。对LTD系统中影响磁芯能量传递效率的原因进行了初步的分析,并利用Pspice软件的非线性磁芯模型对磁芯的工作过程和损耗进行了模拟计算,最后对LTD磁芯的能量传递效率进行了初步的实验研究,在工作电压为20 kV时、脉宽约220 ns时,在2.8 Ω负载上获得了大于60%的能量传递效率。     

球形容器泄爆过程影响因素的数值模拟

为了研究球形容器内气体泄爆过程的影响因素及压力传播的基本规律,从能量守恒方程、质量守恒方程、动量守恒方程及化学组分平衡方程出发,建立了泄爆的数学模型,采用k-ε湍流模型和涡耗散概念模型即EDC燃烧模型,利用Fluent软件对该过程进行数值模拟,得到泄爆过程中不同时刻监测点的压力。用响应面曲线的方法讨论泄孔比、泄爆压力、容器体积对球形容器泄爆过程的影响,结果表明:泄孔比越大,危险系数越大;破膜压力过大或过小都将增大危险性;容器体积越大,越容易产生危险。因此,实际球形容器防爆泄压中,合理控制泄爆孔径、破膜压力和容器体积将对泄爆过程中产生的影响及泄爆效果至关重要。     

Inhibition of Inflammation‐Associated Thrombosis with ROS‐Responsive Heparin‐DOCA/PVAX Nanoparticles

Inflammation‐associated thrombosis is a non‐negligible source of mortalities and morbidities worldwide. To manipulate inflammation‐associated coagulation, nanoparticles that contain anti‐inflammatory polymer (copolyoxalate containing vanillyl alcohol, PVAX) and anti‐thrombotic heparin derivative deoxycholic acid (Hep‐DOCA) are prepared. The strategy takes advantage of the reducted side effects of heparin through heparin conjugation, achievement of long‐term anti‐inflammation by inflammation‐trigged release of anti‐inflammatory agents, and formation of PVAX/heparin‐DOCA nanoparticles by co‐self‐assembly. It is demonstrated that the Hep‐DOCA conjugate and PVAX are synthesized successfully; PVAX and Hep‐DOCA nanodrugs (HDP) are obtained by co‐assembly; the HDP nanoparticles effectively reduce the inflammation and coagulation without inducing lethal bleeding both in vivo and in vitro. The method provided here is versatile and effective, which paves new way to develop nanodrugs to treat inflammation‐associated thrombosis safely.     

Highly efficient sorption of U(VI) from aqueous solution using amino/amine-functionalized magnetic mesoporous silica nanospheres

The amino/amine-functionalized magnetic mesoporous silica nanospheres (MSN-DETA) exhibited relatively high sorption capacity (q_m?=?153.68 mg/g) as well as excellent selectivity for U(VI). The U4f_7/2 X-ray photoelectron spectrometry revealed two binding energies at 380.8?±?0.3 eV (with the proportion of 75.2%) and 382.3?±?0.3 eV, which indicated the inner-surface complexation mechanism. The sorption isotherms fitted well with the Langmuir model, whereas the sorption kinetics could be fitted by pseudo-second-order model. The U(VI)-loaded MSN-DETA could be efficiently regenerated by acidified EDTA (0.4 M). These findings indicated that MSN-DETA could be used as a potential material for the efficient sorption/separation of U(VI) from wastewater.

     

Synthesis and Characterization of Cyclopropaosmanaphthalenes Containing a Fused σ‐Aromatic Metallacyclopropene Unit

Metalla‐aromatics are important complexes that show unique properties owing to their highly conjugated systems, which show Hückel or Möbius aromaticity. Recently, several metalla‐aromatics showing spiro‐aromaticity or σ‐aromaticity have been reported. Herein, we report the isolation of the first cyclopropametallanaphthalenes, in which the metallacyclopropene ring shows σ‐aromaticity and weak hyperconjugative aromaticity. The reaction of OsCl₂(PPh₃)₃ with o‐ethynylphenyl alkynes in the presence of PPh₃ followed by protonation with HCl yielded the first cyclopropametallanaphthalenes. The reaction mechanism and the aromaticity were also investigated by density functional theory studies.     

基于硅材料的分子印迹聚合物的制备及应用*

分子印迹聚合物因制备简单、稳定性好、且具有分子识别功能使其在色谱分离、固相萃取、化学传感、模拟酶催化等方面有了广泛的应用。近年来,基于硅的分子印迹聚合物发展较为快速。本文主要介绍了以硅为母体材料和以硅为基质材料的分子印迹聚合物的制备及分子识别性质研究,并对其应用进行了分类,在此基础上对其将来的发展进行了展望。     

基于压缩感知与小波域奇异值分解的图像认证

提出了一种基于压缩感知与小波域奇异值分解的图像哈希认证新方法.该方法首先通过小波变换得到图像的低频子带,然后对低频子带进行基于块的奇异值分解,最后对产生的最大奇异值数组进行基于压缩感知的随机投影,产生哈希认证信息,并偕同原图像传送到接收端.图像接收端通过比较哈希信息完成图像认证,并通过利用传递的哈希信息重建原始图像的奇异值,进一步映射奇异值差值到图像像素域,从而实现对图像篡改的识别与定位.大量实验结果证明了该方法的有效性.