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991.
研究了一种新型纳米铂修饰玻碳电极的制备方法,并对其电化学催化性能进行了研究。实验结果表明,通过电沉积前在金刚石粉末悬浊液中对玻碳电极进行超声处理,可制备出新型玻碳电极。经超声处理后,金刚石颗粒在玻碳电极基体上产生了数微米长的划痕。电沉积过程中,在该电极上可沉积分布较密集的平均尺寸为110nm的Pt颗粒。这种新型纳米铂修饰玻碳电极的表面电化学活性值为0.397 m2/g,高于普通铂修饰玻碳电极,且在0.5 mol/L H2SO4溶液中具有良好的电化学稳定性。 相似文献
992.
葡萄果皮中黄酮醇以糖苷形式存在,采用正交实验设计,建立了葡萄果皮中黄酮醇糖苷的适宜提取方法,并优化了色谱分析条件。以体积分数50%乙醇和1%乙酸混合液为提取溶剂,室温下超声处理35 min,提取4次,可获得最大提取率;在流动相A为V(乙腈):V(甲酸):V(水)=5∶8.5∶86.5,B为V(乙腈):V(甲醇):V(甲酸):V(水)=25∶45∶8.5∶21.5下梯度洗脱,50 min内可将12种黄酮醇糖苷有效分离。糖甘含量在0.94~423 mg/L范围内线性关系良好,相关系数达到0.999,检出限为35μg/L,定量限为106μg/L;加标回收率在80%~120%之间,相对标准偏差均小于6%。研究表明,以槲皮素-3-O-葡萄糖苷为外标,以质谱信息为基础,应用所建立的方法可以满足不同发育期葡萄果皮中黄酮醇糖苷定性和相对定量分析的要求。 相似文献
993.
应用气相色谱-质谱法测定酒中23种邻苯二甲酸酯残留量。样品在沸水浴中加热除去乙醇后用正己烷提取。离心分离后上清液经DB-5MS石英毛细管色谱柱分离,在选择离子检测模式下进行质谱测定。23种邻苯二甲酸酯的质量浓度均在0.1~10mg·L-1范围内与其峰面积呈线性关系,方法的测定下限(10S/N)为0.5mg·kg-1(DINP及DIDP)和0.1mg·kg-1(其余21种邻苯二甲酸酯)。以空白样品为基体进行加标回收试验,所得回收率在84.1%~100%之间。 相似文献
994.
995.
半个多世纪以来,碳纤维及碳纤维增强复合材料因其优异的力学性能、比强度、比模量、轻质、导电性以及热/化学稳定性,逐渐成为航空航天、建筑、运输、生物医用、体育用品以及电子电气等诸多应用领域一类非常重要的高性能结构材料。近二十多年来,得益于纳米材料与技术以及高效可再生能源器件的迅速发展,力学性能突出的碳纤维(包括工业化碳纤维、碳纤维织物、碳纳米纤维以及碳纳米管纤维等)凭借高的导电性、电化学特性、多孔以及表面可修饰性等优点,开始作为良好的电极材料应用于多种电化学能源器件与光电转换能源器件中,并得到了广泛的研究。本文首次综述了碳纤维基能源器件的研究进展,从认识碳纤维的发展历史与应用出发,介绍了碳纤维的表面功能化与电极制备的相关基础知识,重点综述了当前国内外碳纤维能源器件的发展概况,详细介绍了碳纤维作为功能电极材料在燃料电池、微生物燃料电池、锂离子电池、电化学电容器以及太阳能电池等领域的研究和发展概况。最后,通过分析当前碳纤维能源器件研究领域的现状,对该领域在材料制备工艺、电极设计、器件性能优化与器件集成技术等方面面临的挑战和未来研究方向进行了预测和探讨。 相似文献
996.
Dr. Guanjun Xiao Dr. Chunye Zhu Prof. Yanming Ma Prof. Bingbing Liu Prof. Guangtian Zou Prof. Bo Zou 《Angewandte Chemie (International ed. in English)》2014,53(3):729-733
There is an urgent need for the development in the field of the magnetism of topological insulators, owing to the necessity for the realization of the quantum anomalous Hall effect. Herein, we discuss experimentally fabricated nanostructured hierarchical architectures of the topological insulator Bi2Te3 without the introduction of any exotic magnetic dopants, in which intriguing room‐temperature ferromagnetism was identified. First‐principles calculations demonstrated that the intrinsic point defect with respect to the antisite Te site is responsible for the creation of a magnetic moment. Such a mechanism, which is different from that of a vacancy defect, provides new insights into the origins of magnetism. Our findings may pave the way for developing future Bi2Te3‐based dissipationless spintronics and fault‐tolerant quantum computation. 相似文献
997.
Structure‐Based Rational Design of Prodrugs To Enable Their Combination with Polymeric Nanoparticle Delivery Platforms for Enhanced Antitumor Efficacy 下载免费PDF全文
Dr. Hangxiang Wang Haiyang Xie Jiaping Wu Xuyong Wei Dr. Lin Zhou Prof. Xiao Xu Prof. Shusen Zheng 《Angewandte Chemie (International ed. in English)》2014,53(43):11532-11537
Drug‐loaded nanoparticles (NPs) are of particular interest for efficient cancer therapy due to their improved drug delivery and therapeutic index in various types of cancer. However, the encapsulation of many chemotherapeutics into delivery NPs is often hampered by their unfavorable physicochemical properties. Here, we employed a drug reform strategy to construct a small library of SN‐38 (7‐ethyl‐10‐hydroxycamptothecin)‐derived prodrugs, in which the phenolate group was modified with a variety of hydrophobic moieties. This esterification fine‐tuned the polarity of the SN‐38 molecule and enhanced the lipophilicity of the formed prodrugs, thereby inducing their self‐assembly into biodegradable poly(ethylene glycol)‐block‐poly(d,l ‐lactic acid) (PEG‐PLA) nanoparticulate structures. Our strategy combining the rational engineering of prodrugs with the pre‐eminent features of conventionally used polymeric materials should open new avenues for designing more potent drug delivery systems as a therapeutic modality. 相似文献
998.
Hybrid Fibers Made of Molybdenum Disulfide,Reduced Graphene Oxide,and Multi‐Walled Carbon Nanotubes for Solid‐State,Flexible, Asymmetric Supercapacitors 下载免费PDF全文
Dr. Gengzhi Sun Xiao Zhang Rongzhou Lin Jian Yang Prof. Hua Zhang Prof. Peng Chen 《Angewandte Chemie (International ed. in English)》2015,54(15):4651-4656
One of challenges existing in fiber‐based supercapacitors is how to achieve high energy density without compromising their rate stability. Owing to their unique physical, electronic, and electrochemical properties, two‐dimensional (2D) nanomaterials, e.g., molybdenum disulfide (MoS2) and graphene, have attracted increasing research interest and been utilized as electrode materials in energy‐related applications. Herein, by incorporating MoS2 and reduced graphene oxide (rGO) nanosheets into a well‐aligned multi‐walled carbon nanotube (MWCNT) sheet followed by twisting, MoS2‐rGO/MWCNT and rGO/MWCNT fibers are fabricated, which can be used as the anode and cathode, respectively, for solid‐state, flexible, asymmetric supercapacitors. This fiber‐based asymmetric supercapacitor can operate in a wide potential window of 1.4 V with high Coulombic efficiency, good rate and cycling stability, and improved energy density. 相似文献
999.
Precise Macroscopic Supramolecular Assembly by Combining Spontaneous Locomotion Driven by the Marangoni Effect and Molecular Recognition 下载免费PDF全文
Meng Xiao Yiming Xian Prof. Dr. Feng Shi 《Angewandte Chemie (International ed. in English)》2015,54(31):8952-8956
Macroscopic supramolecular assembly bridges fundamental research on molecular recognition and the potential applications as bulk supramolecular materials. However, challenges remain to realize stable precise assembly, which is significant for further functions. To handle this issue, the Marangoni effect is applied to achieve spontaneous locomotion of macroscopic building blocks to reach interactive distance, thus contributing to formation of ordered structures. By increasing the density of the building blocks, the driving force for assembly transforms from a hydrophobic–hydrophobic interaction to hydrophilic–hydrophilic interaction, which is favorable for introducing hydrophilic coatings with supramolecular interactive groups on matched surfaces, consequently realizing the fabrication of stable precise macroscopic supramolecular assemblies. 相似文献
1000.
Organic Crystals with Near‐Infrared Amplified Spontaneous Emissions Based on 2′‐Hydroxychalcone Derivatives: Subtle Structure Modification but Great Property Change 下载免费PDF全文
Xiao Cheng Kai Wang Shuo Huang Dr. Houyu Zhang Prof. Dr. Hongyu Zhang Prof. Dr. Yue Wang 《Angewandte Chemie (International ed. in English)》2015,54(29):8369-8373
A series of highly efficient deep red to near‐infrared (NIR) emissive organic crystals 1 – 3 based on the structurally simple 2′‐hydroxychalcone derivatives were synthesized through a simple one‐step condensation reaction. Crystal 1 displays the highest quantum yield (Φf) of 0.32 among the reported organic single crystals with an emission maximum (λem) over 710 nm. Comparison between the bright emissive crystals 1 – 3 and the nearly nonluminous compounds 4 – 7 clearly gives evidence that a subtle structure modification can arouse great property changes, which is instructive in designing new high‐efficiency organic luminescent materials. Notably, crystals 1 – 3 exhibit amplified spontaneous emissions (ASE) with extremely low thresholds. Thus, organic deep red to NIR emissive crystals with very high Φf have been obtained and are found to display the first example of NIR fluorescent crystal ASE. 相似文献