红、绿CdSe@ZnS量子点配比对三波段标准白光LED器件的影响

将一步法合成的具有梯度合金结构的红光、绿光CdSe@ZnS量子点与硅胶均匀混合后,作为光转换层涂覆到蓝色InGaN LED芯片上,制备了不含荧光材料的三波段白光LED器件。研究了峰值为650 nm和550 nm的高效率红、绿量子点在硅胶中的含量及配比对白光LED色坐标以及效率的影响。结果表明,当红、绿量子点配比为2：3时,可得到发射纯正白光的QDs-LED器件,色坐标为（0.322 8,0.335 9）、色温为5 725 K,功率效率为26.61 lm/W,显色指数为72.7。光谱中红、蓝、绿三色发光峰的半高宽分别为30,25,38 nm,表明器件具有很好的单色性和高色纯度。     

覆盖多柔性层的有限长圆柱壳声辐射特性

研究了有限长圆柱壳覆盖多层柔性材料的声辐射特性。根据相邻柔性层界面上的边界条件推导了柔性层系的传递矩阵,结合薄壳理论和声波动方程建立了分析覆盖多柔性层后圆柱壳声辐射的理论模型。通过数值计算表明,减小柔性层的声速或者密度均能增加辐射声功率降低量,而采用多柔性层结构能比相应的单层均匀柔性材料获得更好的降噪效果。     

核-壳结构CdSe/ZnS量子点的制备、硫醇修饰及其光学性能

采用高温有机相包覆技术制备了CdSe/ZnS核壳结构量子点材料,考察了包覆量对量子点材料的光学性能的影响,研究了含脂肪链和芳香基的双硫醇分子1,4-苯二甲硫醇和1,8-辛二硫醇对于具有核-壳结构的CdSe/ZnS量子点材料的修饰作用,考察了修饰作用对于量子点的量子效率和荧光强度等光学性能的影响.实验结果表明:随着硫化锌包覆量的增加,量子点的量子效率及其荧光发射强度明显提高;硫醇的修饰能显著增强量子点的发光强度,随着硫醇浓度的增加,其发光性能增强,但是达到一定程度后,光学性能基本不随硫醇浓度的变化而变化.根据固体核磁共振等实验结果推测:硫醇分子可能部分替代了量子点体系中的正三辛基氧膦配体,稳定了量子点体系,对量子点起修饰保护作用,从而提高了量子点的光学性能.     

表面水热碳层对磁性NiFe2O4八面体光催化活性的影响

采用葡萄糖水热碳化法合成了一系列碳层包覆的NiFe₂O₄核壳八面体(NiFe₂O₄@C). 通过调控葡萄糖的含量可以有效控制NiFe₂O₄表面包覆的碳层厚度. 利用X射线衍射(XRD)、 拉曼光谱(Roman)、 X射线光电子能谱(XPS)、 扫描电子显微镜(SEM)、 透射电子显微镜(TEM)和紫外-可见漫反射光谱(UV-Vis DRS)等对NiFe₂O₄@C的组成、 结构、 形貌和光学性能进行了表征. 考察了表面水热碳层对NiFe₂O₄光催化降解亚甲基蓝(MB)性能的影响. 结果表明, NiFe₂O₄的光催化活性很大程度上依赖于在其表面包覆的碳层厚度, 碳层厚度为5.5 nm的NiFe₂O₄@C-3展现了最佳的光催化活性. 荧光光谱(PL)、 瞬态光电流和电化学阻抗谱(EIS)表征结果证明, NiFe₂O₄@C的光催化性能的提升归因于在NiFe₂O₄核和碳壳之间形成了异质结, 有效地促进了光生载流子的传输和分离效率. NiFe₂O₄@C复合材料展现了较好的稳定性和可回收性, 在污水处理方面有很大的应用潜力.     

SiO2/聚甲基丙烯酸叔丁酯核壳复合微粒的制备与表征

以甲基丙烯酸-3-(三甲氧基硅基)丙酯(MPS)修饰的SiO2胶体粒子为种子,甲基丙烯酸叔丁酯(tBMA)为单体、十二烷基硫酸钠(SDS)为乳化剂,采用种子乳液聚合法制备了SiO2/聚甲基丙烯酸叔丁酯的核壳复合微粒。微粒经水解后形成具有pH敏感性的无机/有机复合微粒。研究了影响核壳复合微粒形态结构的因素,结果发现,控制SiO2种子乳液的质量分数在1.5%～2%,可避免聚合过程中生成纯聚甲基丙烯酸叔丁酯乳胶粒子;反应体系中乳化剂SDS的用量超过质量分数0.3%时,易形成纯聚合物乳胶粒子;SDS用量低于质量分数0.15%时,生成的核壳复合微粒易产生团聚;单体和交联剂用量升高,核壳复合微粒的壳层厚度增加,用量过高会导致核壳复合微粒出现团聚现象,并且有纯聚合物乳胶粒子生成。采用TEM、NMR和FTIR及接触角测试技术分析结果表明,复合微粒是由SiO和聚甲基丙烯酸叔丁酯组成的核壳结构微粒。     

基于两势方法系统研究壳结构对原子核α衰变的影响

基于两势方法（two-potential-approach,TPA）系统研究了偶-偶核、奇-A核和奇-奇核α衰变半衰期。为了考虑原子核的壳结构的影响而导致的实验半衰期与计算结果之间的偏差,引入了与α结团形成概率相关的禁戒因子和预形成因子。结合前期相关工作[X.D.Sun et al.,Phys.Rev.C 93,034316（2016）;X.D.Sun et al.,Phys.Rev.C 95,014319（2017）;X.D.Sun et al.,Phys.Rev.C 95,044303（2017）],考虑到壳效应对α粒子预形成的影响,通过分析α衰变半衰期的实验数据,拟合得到了α粒子预形成因子/禁戒因子修正公式的参数,得到了α衰变预形成因子/禁戒因子的计算结果,证实了壳效应及质子-中子相互作用在α结团形成过程中起着重要的作用,离壳越近预形成概率越小离壳越远预形成概率越大。In the present work, the α decay half-lives are systematically studied within the two-potentialapproach for even-even nuclei, odd-A nuclei and odd-odd nuclei. To describe the deviations between experimental half-lives and calculated results due to the nuclear shell structure, α preformation factor and hindrance factor related with α cluster preformation probability are introduced. It is consistent with our previous works[X. D. Sun et al., Phys. Rev. C 93, 034316 (2016); X. D. Sun et al., Phys. Rev. C 95, 014319 (2017); X. D. Sun et al., Phys. Rev. C 95, 044303 (2017)]. Considering the shell effect on the preformation of α and by analyzing the experimental data of the α decay half-lives, the parameters of the α preformation factor/hindrance factor correction formula are obtained. we confirm that the shell effect and the proton-neutron correlation play key roles in the α preformation where the preformation probability near the shell is less than the preformation probability far from the shell.     

核壳结构NH2-UiO-66@TiO2的制备及其可见光下的甲苯降解性能研究

Metal-organic frameworks (MOFs) are of significant interest for photocatalysis using visible light, but they are typically limited by the instability and high recombination ratio of photoexcited pairs. Integrating MOFs into an inorganic semiconductor is one of the most widespread methods to promote their activity. In this study, a core-shell structured MOF@TiO₂ (NH₂-UiO-66@TiO₂) was synthesized as an efficient photocatalyst for the degradation of toluene. Pristine NH₂-UiO-66 was synthesized by a hydrothermal method as the core, which was then coated with an amorphous TiO₂ shell. Compared with pristine NH₂-UiO-66 and other samples prepared by the direct mixing of NH₂-UiO-66 and TiO₂, NH₂-UiO-66@TiO₂ exhibited a higher degradation rate of toluene. Using NH₂-UiO-66@TiO₂ as a catalyst, the degradation efficiency of toluene reached 76.7% within 3 h, which is 1.48 times higher than that of NH₂-UiO-66. The degradation performance was also stable in four repeated reuse experiments, and the slight deactivation was reactivated after washing with ethanol. A series of characterization methods were used to determine the physicochemical properties of NH₂-UiO-66@TiO₂, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Using the measured physicochemical properties, the photocatalytic mechanism of NH₂-UiO-66@TiO₂ was explored. NH₂-UiO-66 is an ideal photocatalyst, with visible-light response and a huge specific surface area (914.9 m²·g^-1), which is favorable for the utilization of sunlight as well as the absorption of pollutants in indoor air. In addition, a new interface formed between the two components (NH₂-UiO-66 and TiO₂), which efficiently broaden the light absorption area and enhanced the utilization of photogenerated species. The photogenerated holes and electrons could transfer through the interlayer as soon as they were formed. It is speculated that holes would transfer to the HOMO of NH₂-UiO-66, and then combine with H₂O molecules to form hydroxyl radicals (·OH). At the same time, more electrons tended to combine with oxygen molecules in the conduction band of TiO₂ rather than recombine with holes. Consequently, the recombination rate of electrons and holes decreased, while the quantity of oxygen radicals and hydroxyl radicals increased. Toluene was efficiently oxidized by these two types of radicals. Owing to the outstanding properties mentioned above, the strategy of constructing NH₂-UiO-66@TiO₂ is considered to be an effective approach. This work may provide new insights into the design of core-shell structured MOF@photocatalysts for the photocatalytic degradation of indoor air pollutants.      

核壳结构的Co3O4@δ-MnO2/Pt作为锂氧电池高效催化正极

通过简易、可控的水热方法在泡沫镍基体上直接生长了核壳结构的阵列型Co₃O₄@δ-MnO₂/Pt正极。阵列电极有利于电极的润湿、氧气的传输和Li₂O₂的负载。Co₃O₄@δ-MnO₂/Pt正极对氧还原和氧析出反应具有高的催化性能,可促使Li₂O₂依附Co₃O₄@δ-MnO₂/Pt阵列生长,从而保持阵列结构。该生长行为有利于Li₂O₂在充电时分解。以Co₃O₄@δ-MnO₂/Pt为催化正极的锂氧电池显示出高的容量（在电流密度100 mA·g^-1时容量为2 480 mAh·g^-1）,以及长的循环寿命（容量限定在500 mAh·g^-1时,在200 mA·g^-1电流密度下,可循环65次）,该性能超过了使用Co₃O₄或Co₃O₄@δ-MnO₂催化剂的电池。     

海胆状氧化锌/羰基铁粉核壳结构复合粒子的抗氧化及吸波性能

针对羰基铁粉吸收剂在温度较高时易被氧化的问题,采用水热法制备了氧化锌包覆羰基铁粉核壳结构复合粒子,并分别将羰基铁粉和氧化锌/羰基铁粉核壳粒子与石蜡混合,制备复合材料。结果表明,氧化锌纳米棒致密的包覆在羰基铁粉颗粒表面形成海胆状核壳结构复合粒子,正是这种结构将羰基铁粉颗粒与空气隔绝,使得复合粒子的抗氧化性能得到显著改善。与羰基铁粉复合吸波材料相比,氧化锌/羰基铁粉核壳粒子的复合材料吸收峰稍向低频移动,反射损耗小于-5dB的带宽几乎保持不变,在不改变电磁吸波性能的前提下,提高了羰基铁粉粒子的使用温度。     

预应力杂交结构的屈曲分析

含有预应力索的半刚性大跨度空间结构是一种非常有生命力的杂交钢结构形式,对应用日益广泛的空间杂交结构的正确分析是保证结构安全设计的前提,屈曲分析通常是这类结构分析的主要内容之一,结构的屈曲分析可分为特征值屈曲分析和非线性屈曲分析。论文首先阐述了结构特征值屈曲分析和非线性屈曲分析中的分枝屈曲分析的基本理论,提出了含有恒定荷载的预应力结构特征值的求解方法,明确正确应用屈曲理论对保证工程安全设计的重要性,然后应用有限元软件ANSYS对待建的安徽大学体育馆新型弦支网壳屋盖结构进行了特征值屈曲分析和分枝屈曲分析,提出应用通用有限元程序跟踪结构分枝屈曲路径的方法,本文结论对预应力杂交结构的屈曲分析具有指导意义。