Host–Guest Doping in Flexible Organic Crystals for Room-Temperature Phosphorescence

Organic single crystals (OSCs) with excellent flexibility and unique optical properties are of great importance due to their broad applicability in optical/optoelectronic devices and sensors. Nevertheless, fabricating flexible OSCs with room-temperature phosphorescence (RTP) remains a great challenge. Herein, we propose a host–guest doping strategy to achieve both RTP and flexibility of OSCs. The single-stranded crystal is highly bendable upon external force application and can immediately return to its original straight shape after removal of the stress, impressively emitting bright deep-red phosphorescence. The theoretical and experimental results demonstrate that the bright RTP arises from Förster resonance energy transfer (FRET) from the triphenylene molecules to the dopants. This strategy is both conceptually and synthetically simple and offers a universal approach for the preparation of flexible OSCs with RTP.     

三功能策略设计制备具有优异低温抗积碳性能的Ni-CeO2@SiO2催化剂催化甲烷干重整反应

随着全球人为温室气体排放量(主要是甲烷和二氧化碳)的增加,全球变暖的趋势逐渐增加,因此,迫切需要通过各种技术来捕获和利用这些温室气体.甲烷干气重整反应(DRM)可以有效地将甲烷和二氧化碳这两种资源丰富、价格低廉的温室气体转化为高附加值化学品,减少它们向大气排放.尽管DRM工艺的应用具有许多优势,但是反应期间碳沉积和活性组分的烧结是阻碍其工业应用的两个主要原因.这些碳沉积物可能覆盖活性中心或阻塞催化剂的孔道,从而导致催化剂活性降低.镍基催化剂因其价格低廉、初始活性高和资源丰富而得到广泛的应用.但应用于DRM反应的Ni基催化剂在反应中容易烧结和积碳,导致催化剂迅速失活.为解决上述问题,本文从三功能策略角度出发,即SiO2壳层的限域作用和Ni-Ce之间的协同作用以及CeO2的消除积碳作用,采用原位一锅法设计合成了一种限域型Ni-CeO2核壳结构催化剂(Ni-CeO2@SiO2).通过X射线衍射、透射电子显微镜、能量色散X射线光谱、N2吸附/脱附、氢气程序升温还原和脱附、氧气程序升温脱附、拉曼光谱、热重分析和原位漫反射红外傅里叶变换光谱测试对催化剂进行了系统的表征,来揭示催化剂的理化性质和反应机理.催化剂应用于甲烷干气重整反应结果表明,在温度区间为550～800℃时,与传统浸渍法合成的催化剂相比,Ni-CeO2@SiO2催化剂具有更高的活性.高温800℃下的稳定性测试结果显示,传统浸渍法合成的催化剂在反应20 h后就出现了大量的积碳且活性下降明显;而Ni-CeO2@SiO2催化剂在800℃下反应100 h后未检测到积碳,并且催化剂中的Ni纳米颗粒的平均粒径从5.01 nm仅增长到5.77 nm,表现出很好的高温抗积碳和耐烧结性能.值得注意的是,Ni-CeO2@SiO2催化剂在低温600℃(形成碳沉积的最可能温度区域)下反应20h后也未检测到积碳的形成,表现出催化剂良好的低温稳定性和抗积碳性能.这可能归因于对Ni-CeO2@SiO2催化剂的三功能作用,即多孔二氧化硅壳层的限域作用、Ni与CeO2之间强的金属-金属氧化物相互作用以及具有丰富活性氧物种CeO2的消除积碳的作用.通过原位漫反射红外傅里叶变换光谱测试来探究反应机理.结果 表明,DRM反应在Ni-CeO2@SiO2催化剂上遵循L-H机理,添加CeO2可以消除碳沉积并促进CO2活化.该三功能策略为设计其他应用于DRM的高性能催化剂提供了指导,有望加快该工艺的工业化.     

Effects of a High-Molecular-Weight Polysaccharides Isolated from Korean Persimmon on the Antioxidant,Anti-Inflammatory,and Antiwrinkle Activity

Persimmon (Diospyros kaki), a familiar and widespread fruit worldwide, is known to exhibit several physiological effects because of the presence of pharmacologically active compounds called phytochemicals. However, its high-molecular-weight compounds, particularly polysaccharides, have not been extensively studied. In this study, D. kaki extract (DK) was fractionated into low- and high-molecular-weight fractions (DK-L and DK-H, respectively) through ethanol fractionation, and their effects on antioxidant, anti-inflammatory, and antiwrinkle activities were investigated by an in vitro system. DK-H contained significantly higher contents of neutral sugar, uronic acid, and polyphenols compared to DK and DK-L. Furthermore, DK-H exhibited significantly improved pharmacological activities, such as antioxidant, anti-inflammatory, and antiwrinkle properties, compared to those of DK and DK-L, demonstrating that DK-H may play an important role in mediating the beneficial effects of persimmon. Sugar composition analysis and molecular characterization indicated that DK-H consisted of a galacturonic acid (GalA)-rich polysaccharide with a molecular weight of >345 kDa that mainly comprised GalA and small amounts of neutral sugar and polyphenol residues. These results suggest that the bioactive fraction DK-H is likely to be a GalA-rich pectic polysaccharide containing a small number of polyphenol residues, which may be a novel candidate in the pharmaceutical and cosmeceutical industries.     

Biflavones and Furanone Glucosides from Zabelia tyaihyonii

Two new biflavones, (aR)‐3′‐methoxycupressuflavone ( 1 ) and (aR)‐3′,3′′′‐dimethoxycupressuflavone ( 2 ), and two new furanone glucosides, zabeliosides A and B ( 3 and 4 , resp.), along with two known biflavones, cupressuflavone ( 5 ) and amentoflavone ( 6 ), were isolated from the leaves of Zabelia tyaihyonii. The structures of the new compounds were elucidated by 1D‐ and 2D‐NMR, HR‐ESI‐MS, and circular dichroism.     

The banded spherulites of iPP induced by pressure vibration injection molding

Isotactic polypropylene(i PP) samples obtained by pressure vibration injection molding(PVIM) and conventional injection molding(CIM) were studied by polarized-light microscopy(PLM), respectively. It was found that the alternating bright and dark banded spherulites were generated in the transitional region of PVIM parts. It is the first time that the banded spherulites of isotactic polypropylene were observed in polymer processing. What's more, the banded spherulites were proved to be constituted of ?-form crystal by hot stage polarized-light microscopy(HT-PLM) and wide angle X-ray diffraction(WAXD). Morphology of the banded spherulites was also studied by scaning electronical microscopy(SEM).     

有机相变材料的发展及在纺织领域的应用

相变材料因为其优良的热性能,被广泛应用于纺织品、航空航天、交通运输、农业、国防、建材、太阳能系统和医疗设备等领域。近年来,开发应用新型相变材料已经成为研究热点。本文首先概括介绍了相变材料发展进程,着重介绍了有机相变材料,包括它的分类、性能和应用。详细介绍了有机相变材料在纺织行业的应用,以及对调温纺织品测试手段的研究和建立的相关数学模型的建立。     

Cysteine‐Mediated Intracellular Building of Luciferin to Enhance Probe Retention and Fluorescence Turn‐On

The development of sensitive and selective small molecular probes that enable real‐time detection of endogenous cysteine (Cys) has become an attractive topic because of the essential roles played by Cys in controlling the cellular nitrogen balance and in maintaining biological redox homeostasis. Herein, we report a Cys‐specific probe, 2‐cyanobenzothiazol‐6‐yl acrylate (CBTOA), that shows not only fluorescence turn‐on for sensitive detection of endogenous Cys but also enhanced probe retention inside cells for real‐time monitoring of Cys levels upon external stimulation. Cys‐mediated intracellular formation of luciferin from CBTOA was the key strategy leading to this new type of fluorogenic probe. CBTOA showed fast response to Cys in living cells and liver tissue slices with high sensitivity and selectivity. By using CBTOA as a real‐time probe, we were able to monitor the change in Cys levels in living HeLa cells under ROS‐induced oxidative stress as well as in human mesenchymal stem cells during adipogenic differentiation.     

Distributed Bragg reflector laser(1.8 μm) with 10 nm wavelength tuning range

We report a 1.8 μm two-section distributed Bragg reflector laser using butt-jointed In Ga As P bulk material as the waveguide core layer. The threshold current is 17 m A and the output power is 8 m W on average. The threshold current, output power, and emitting wavelength dependences on temperature are measured. The obtained wavelength tuning range is 10 nm. This device has potential applications in simultaneous multiple-gas detection.     

几种外场对费米共振的影响:费米共振的拉曼光谱研究

费米共振是分子内和分子间发生的基团间的振动耦合和能量转移现象。有关外场中费米共振的认识、拉曼光谱的研究方法及应用均待开发和推广。本文系统阐述了利用高压DAC技术、变温技术特别是课题组独创的变换溶剂浓度、LCOF等方法获得的有关费米共振的研究成果,即分子场、压力场、温度场等外场对分子内和分子间费米共振的影响:(1)分子场中a.由C_5H_5N在CH_3OH和H_2O中拉曼光谱变化研究表明溶剂效应对费米共振有明显影响;b.通过改变溶液浓度发现了其他方法未能发现的费米共振双线对非对称移动及双线对中倍频的基频亦受费米共振调谐的现象;c.溶液中的氢键、反氢键使分子基团重组而对费米共振产生显著影响;d.C_7H_8和m-C_8H_(105分子间发生会费米共振,且费米共振特性随溶液浓度明显改变;(2)压力场中a.随压强增加谱线蓝移,且频差△随压强改变而引起W改变;b.随压强增加CCl_4在C_6H_6中的v_1+v_4~v_3的W减小速度比纯液体中快,费米共振消失提前。这表明,压强引起的费米共振现象可揭示溶剂效应机理;(3)温度场中温度会影响分子费米共振特性,且对不同分子影响亦不同,温度对CO_2的费米共振影响较大,而对CS_2几乎无影响。本文对分子谱线的认证与归属、分子构象的确定及异构体的鉴别、氢键对分子结构与性质的影响等方面的研究提供了系统的理论与实验依据。