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51.
Pressurized hot water extraction (PHWE) using a laboratory made system was applied for the extraction of thermally labile and reasonably polar components such as berberine in coptidis rhizoma, glycyrrhizin in radix glycyrrhizae/liquorice and baicalein in scutellariae radix. PHWE was carried out dynamically at a flow of 1 ml/min, temperature between 95 and 140 °C, an applied pressure of 10-20 bar and extraction time of 40 min. Extraction by PHWE was found to give efficiencies comparable to Soxhlet extraction for baicalein in scutellariae radix and sonication for berberine in coptidis rhizoma, and glycyrrhizin in radix glycyrrhizae. Effects of ethanol added into the water used in PHWE were explored. Pressurized liquid extraction (PLE) with methanol as solvent was used for extraction of baicalein in scutellariae radix. The marker compounds present in the various medicinal plant extracts were determined by gradient elution HPLC. 相似文献
52.
A novel oligothiophene derivative containing the triphenylamine moiety with high glass transition temperature (Tg; 135 °C), 5,5′‐{bis[4‐di(4‐thiophenyl)amino]phenyl}‐2,2′‐bithiophene (TTPA‐dimer) was synthesized by the dimerization of tris[4‐(2‐thienyl)phenyl]amine (TTPA) with a palladium catalysis. Some types of electroluminescent (EL) devices that use the amorphous material for a hole‐ and an electron‐transporting with an emitting layer were fabricated. These devices emitted a bright green‐yellowish light (λemi; around 510 nm) with a small full width at half maximum (FWHM) rather than that of Alq3. The single layer EL device showed a maximum luminance of 221 cd/m2 at 8 V (0.06 lm/W at 100 cd/m2). On the other hand, the double layer (TTPA‐dimer/Alq3) EL device that used Alq3 as the electron transport material was increased up to 10830 cd/m2 at 12 V (0.89 lm/W at 300 cd/m2) and with a lower turn‐on voltage (3.2 V at 0.1 cd/m2) than other types of EL devices. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
53.
Chemical Reduction of CO2 to Different Products during Photo Catalytic Reaction on TiO2 under Diverse Conditions: an Overview
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The chemical reduction of CO_2 remains a challenge with respect to the reversal of the oxidative degradation of any organic materials.The conversion of CO_2 into useful substances is essential in developing al- ternative fuels and various raw materials for different in- dustries.This also aids in preventing the continuous rise in tropospheric temperature due to the green house effect of CO_2.In this article an overview of the growth taken place so far in the field of CO_2 chemical reduction is pre- sented.The discussion comprises of photochemical meth- ods for the development of different products,viz.CO, CH_3O_H and CH_4,through chemical reduction of CO_2. This includes the use of photo catalysts,mainly TiO_2, and the role of a hole scavenger(such as 2-propanol)for this purpose. 相似文献
54.
甲烷氧化偶联Na2WO4-Mn/SiO2催化剂热效应的研究 总被引:1,自引:2,他引:1
采用固定床微型反应装置,研究了甲烷氧化偶联反应过程中Na2WO4-Mn/S iO2催化剂床层的热效应和催化性能的关系,考察了反应炉温、CH4/O2比和反应气体空速对催化剂床层热点分布的影响.研究结果表明,甲烷氧化偶联催化剂床层的热效应强烈依赖于反应条件.反应炉温越高,CH4/O2比越低,反应气体空速越大,催化剂床层的热点温度越高.结合催化性能和热效应关系的研究,为优化甲烷氧化偶联的反应操作提供了实验依据. 相似文献
55.
Nogami Masayuki Nagakura Takehito Hayakawa Tomokatsu Kasuga Toshihiro 《Journal of Sol-Gel Science and Technology》2000,19(1-3):253-256
Persistent spectral hole burning was studied in Eu3+ ions-doped Al2O3-SiO2 glass prepared by a sol-gel method. The gel synthesized by the hydrolysis of Si- and Al-alkoxides and EuCl3·6H2O was heated in air and hydrogen gas atmospheres. For the glass heated in air to contain OH bonds, the hole was formed by the photoinduced rearrangement of the OH bonds surrounding the Eu3+ ions, and was thermally refilled and erased above 200 K. On the other hand, the glass heated in hydrogen gas showed the hole spectrum above 200 K. It was found that the hole depth was independent of the temperature and was 7% of the total intensity at room temperature. The proposed mechanism was the electron transfer between the Eu3+ ions and the defect centers formed in glass matrix. 相似文献
56.
星状四芳胺类空穴传输材料的合成 总被引:1,自引:0,他引:1
有机电致发光器件 (OELD)是继阴极射线管平板显示器 (CRT)和液晶显示器 (LCD)之后的第三代平板显示器。它具有主动发光、驱动电压低(2伏左右 )、发光亮度高 (1 3 0 0 0cd m2 以上 ) ,无软X 射线污染 ,响应速度快 (1 0 -6 ~ 1 0 -8秒 )等优点。从 1 987年美藉华人邓清云等提出多层结构的OELD的器件结构以来的十多年间 ,OELD以及其材料的研究已成为显示技术以及显示材料等方面的研究热点 ,发展很快[1~ 3] 。在 1 999年日本先锋公司已开发出了单色的汽车用OEL平板显示器商品 ,今年东芝公司又开发出了 2 .7英寸的彩… 相似文献
57.
Joël Delville 《Applied Scientific Research》1994,53(3-4):263-281
Experiments are performed in an incompressible plane turbulent mixing layer, using various hot wire rake configurations. From these experiments, the Proper Orthogonal Decomposition is applied for kernels where the space-time correlation tensor is evaluated over different spatial meshes and velocity components configurations. The resulting decompositions are then discussed in terms of characterization of the organization of the flow for various scalar or vectorial approaches of the POD. An incrtial range law is evidenced. The instantaneous contribution of the first modes of the POD to the organization of the flow is analyzed. A dynamical behavior for the organization of the flow is observed from the correlation between the first two modes contribution. 相似文献
58.
Chunya Du Hui Liu Zhuang Cheng Shaoqin Zhang Zexing Qu Dezhi Yang Xianfeng Qiao Zujin Zhao Ping Lu 《Advanced functional materials》2023,33(45):2304854
The pursuit for efficient deep blue material is an ever-increasing issue in organic optoelectronics field. It is a long-standing challenge to achieve high external quantum efficiency (EQE) exceed 10% at brightness of 1000 cd m−2 with a Commission International de L'Eclairage (CIEy) <0.08 in non-doped organic light-emitting diodes (OLEDs). Herein, this study reports a deep blue luminogen, PPITPh, by bonding phenanthro[9,10-d]imidazole moiety with m-terphenyl group via benzene bridge. The non-doped OLED based on PPITPh exhibits an exceptionally high EQE of 11.83% with a CIE coordinate of (0.15, 0.07). The EQE still maintains 10.17% at the brightness of 1000 cd m−2, and even at a brightness as high as 10000 cd m−2, an EQE of 7.5% is still remained, representing the record-high result among non-doped deep-blue OLEDs at 1000 cd m−2. The unprecedented device performance is attributed to the reversed intersystem crossing process through hot exciton mechanism. Besides, the maximum EQE of orange phosphorescent OLED with PPITPh as host is 32.02%, and remains 31.17% at the brightness of 1000 cd m−2. Such minimal efficiency roll-off demonstrates that PPITPh is also an excellent phosphorescent host material. The result offers a new design strategy for the enrichment of high-efficiency deep blue luminogen. 相似文献
59.
Pimpisut Worakajit Pinit Kidkhunthod Thanasee Thanasarnsurapong Saran Waiprasoet Hideki Nakajima Taweesak Sudyoadsuk Vinich Promarak Adisak Boonchun Pichaya Pattanasattayavong 《Advanced functional materials》2023,33(25):2209504
Solution-processed copper(I) thiocyanate (CuSCN) typically exhibits low crystallinity with short-range order; the defects result in a high density of trap states that limit the device's performance. Despite the extensive electronic applications of CuSCN, its defect properties are not understood in detail. Through X-ray absorption spectroscopy, pristine CuSCN prepared from the standard diethyl sulfide-based recipe is found to contain under-coordinated Cu atoms, pointing to the presence of SCN− vacancies. A defect passivation strategy is introduced by adding solid I2 to the processing solution. At small concentrations, the iodine is found to exist as I− which can substitute for the missing SCN− ligand, effectively healing the defective sites and restoring the coordination around Cu. Computational study results also verify this point. Applying I2-doped CuSCN as a p-channel in thin-film transistors shows that the hole mobility increases by more than five times at the optimal doping concentration of 0.5 mol.%. Importantly, the on/off current ratio and the subthreshold characteristics also improve as the I2 doping method leads to the defect-healing effect while avoiding the creation of detrimental impurity states. An analysis of the capacitance-voltage characteristics corroborates that the trap state density is reduced upon I2 addition. 相似文献
60.
Yong Ryun Kim Oskar J. Sandberg Stefan Zeiske Gregory Burwell Drew B. Riley Paul Meredith Ardalan Armin 《Advanced functional materials》2023,33(16):2300147
Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) has been one of the most established hole transport layers (HTL) in organic solar cells (OSCs) for several decades. However, the presence of PSS− ions is known to deteriorate device performance via a number of mechanisms including diffusion to the HTL-active layer interface and unwanted local chemical reactions. In this study, it is shown that PSS− ions can also result in local p-doping in the high efficiency donor:non-fullerene acceptor blends – resulting in photocurrent loss. To address these issues, a facile and effective approach is reported to improve the OSC performance through a two-component hole transport layer (HTL) consisting of a self-assembled monolayer of 2PACz ([2-(9H-Carbazol-9-yl)ethyl]phosphonic acid) and PEDOT:PSS. The power conversion efficiency (PCE) of 17.1% using devices with PEDOT:PSS HTL improved to 17.7% when the PEDOT:PSS/2PACz two-component HTL is used. The improved performance is attributed to the overlaid 2PACz layer preventing the formation of an intermixed p-doped PSS− ion rich region (≈5–10 nm) at the bulk heterojunction-HTL contact interface, resulting in decreased recombination losses and improved stability. Moreover, the 2PACz monolayer is also found to reduce electrical shunts that ultimately yield improved performance in large area devices with PCE enhanced from 12.3% to 13.3% in 1 cm2 cells. 相似文献