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11.
以典型的双稳态系统——屈曲梁结构为例,基于等效模型,结合解析、数值和实验手段,研究了双稳态结构中的1/2次谐波共振特性、演化过程、参数调节规律及其对隔振特性的影响.研究发现,当非线性刚度系数或激励幅值增加到一定程度时,系统会在一定带宽下产生显著的1/2次谐波共振;随着激励幅值增加,阻尼系统的1/2次谐波遵循“产生-增强-衰退-消失”的过程,该过程对峰值频率和峰值传递率有重要影响;适当提高非线性强度能有效改善双稳态结构隔振特性.针对双稳态屈曲梁结构开展的实验验证了1/2次谐波特性和隔振特性变化规律. 相似文献
12.
Yanxia Xu Yanbing Lv Ruili Wu Huaibin Shen Huawei Yang Han Zhang Jinjie Li Lin Song Li 《Particle & Particle Systems Characterization》2020,37(3):1900441
Indium phosphide (InP) quantum dots (QDs) are ideal substitutes for widely used cadmium-based QDs and have great application prospects in biological fields due to their environmentally benign properties and human safety. However, the synthesis of InP core/shell QDs with biocompatibility, high quantum yield (QY), uniform particle size, and high stability is still a challenging subject. Herein, high quality (QY up to 72%) thick shell InP/GaP/ZnS core/shell QDs (12.8 ± 1.4 nm) are synthesized using multiple injections of shell precursor and extension of shell growth time, with GaP serving as the intermediate layer and 1-octanethiol acting as the new S source. The thick shell InP/GaP/ZnS core/shell QDs still keep high QY and photostability after transfer into water. InP/GaP/ZnS core/shell QDs as fluorescence labels to establish QD-based fluorescence-linked immunosorbent assay (QD-FLISA) for quantitative detection of C-reactive protein (CRP), and a calibration curve is established between fluorescence intensity and CRP concentrations (range: 1–800 ng mL−1, correlation coefficient: R2 = 0.9992). The limit of detection is 2.9 ng mL−1, which increases twofold compared to previously reported cadmium-free QD-based immunoassays. Thus, InP/GaP/ZnS core/shell QDs as a great promise fluorescence labeling material, provide a new route for cadmium-free sensitive and specific immunoassays in biomedical fields. 相似文献
13.
Polypyrrole Shell@3D‐Ni Metal Core Structured Electrodes for High‐Performance Supercapacitors 下载免费PDF全文
Gao‐Feng Chen Yu‐Zhi Su Pan‐Yong Kuang Zhao‐Qing Liu Dao‐Yi Chen Xu Wu Nan Li Prof. Shi‐Zhang Qiao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(12):4614-4621
Three‐dimensional (3D) nanometal films serving as current collectors have attracted much interest recently owing to their promising application in high‐performance supercapacitors. In the process of the electrochemical reaction, the 3D structure can provide a short diffusion path for fast ion transport, and the highly conductive nanometal may serve as a backbone for facile electron transfer. In this work, a novel polypyrrole (PPy) shell@3D‐Ni‐core composite is developed to enhance the electrochemical performance of conventional PPy. With the introduction of a Ni metal core, the as‐prepared material exhibits a high specific capacitance (726 F g?1 at a charge/discharge rate of 1 A g?1), good rate capability (a decay of 33 % in Csp with charge/discharge rates increasing from 1 to 20 A g?1), and high cycle stability (only a small decrease of 4.2 % in Csp after 1000 cycles at a scan rate of 100 mV s?1). Furthermore, an aqueous symmetric supercapacitor device is fabricated by using the as‐prepared composite as electrodes; the device demonstrates a high energy density (≈21.2 Wh kg?1) and superior long‐term cycle ability (only 4.4 % and 18.6 % loss in Csp after 2000 and 5000 cycles, respectively). 相似文献
14.
在中国科学技术大学夏季学期的研究型实验课程"化学科研基础训练"中开设"壳聚糖的制备与表征"综合实验,以龙虾壳为原料,通过除蛋白、脱盐、脱色、脱乙酰等一系列反应,制备得到目标产物壳聚糖。运用红外光谱、核磁共振仪、黏度法、滴定等对产品的结构及性能进行表征。 相似文献
15.
The construction of nanoscopic materials by synthetic methodologies that iterate covalent and supramolecular interactions has been developed over the past three decades as a powerful method to afford complex functional materials. Indeed, the present study was nearly lost in the archives of dissertation research completed in 2001, which revealed nanoscale conformational dynamics in the segmental reorganization, and partial inversion, of topologically shell crosslinked knedel-like (SCK) nanoparticles. © 2019 Wiley Periodicals, Inc. J. Polym. Sci. 2020 , 58, 204–214 相似文献
16.
Dr. Guang-Lan Li Bei-Bei Yang Xiao-Cun Xu Shuo Cao Prof. Yantao Shi Dr. Yang Yan Dr. Xuedan Song Prof. Ce Hao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(13):2890-2896
The development of cost-effective and durable oxygen electrocatalysts remains highly critical but challenging for energy conversion and storage devices. Herein, a novel FeNi alloy nanoparticle core encapsulated in carbon shells supported on a N-enriched graphene-like carbon matrix (denoted as FeNi@C/NG) was constructed by facile pyrolyzing the mixture of metal salts, glucose, and dicyandiamide. The in situ pyrolysis of dicyandiamide in the presence of glucose plays a significant effect on the fabrication of the porous FeNi@C/NG with a high content of doped N and large specific surface area. The optimized FeNi@C/NG catalyst displays not only a superior catalytic performance for the oxygen reduction reaction (ORR, with an onset potential of 1.0 V and half-wave potential of 0.84 V) and oxygen evolution reaction (OER, the potential at 10 mA cm−2 is 1.66 V) simultaneously in alkaline, but also outstanding long-term cycling durability. The excellent bifunctional ORR/OER electrocatalytic performance is ascribed to the synergism of the carbon shell and FeNi alloy core together with the high-content of nitrogen doped on the large specific surface area graphene-like carbon. 相似文献
17.
Ni-Dimethylglyoxime complex immobilized on functionalized Fe3O4 was synthesized by a post-grafting way and utilized as a novel, thermally stable, recoverable, and efficient for green synthesis of dicoumarols through reaction of 4-hydroxycoumarin with various aldehydes in excellent yields and higher rate. Fe3O4@SiO2-silylcyclopropyl-dimethylglyoxime-Ni superparamagnetic nanoparticles (MNPs) were investigated by Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, vibrating sample magnetometer, and Brunauer–Emmett–Teller technique. This nanocatalyst could be conveniently recovered via the use of an external magnetic field and reused for subsequent reactions for at least 7 times without any remarkable change and decrease in catalytic activity. 相似文献
18.
Yue Liu Mingxin Lv Lu Li Hailong Yu Qiong Wu Jinhui Pang Yuxiang Liu Congxia Xie Shitao Yu Shiwei Liu 《应用有机金属化学》2019,33(4)
An amino‐functionalized silica‐coated Fe3O4 nanocomposite (Fe3O4@SiO2/APTS) was synthesized. The Fe3O4@SiO2 microspheres possessed a well‐defined core–shell structure, uniform sizes and high magnetization. An immobilized ruthenium nanoparticle catalyst (Fe3O4@SiO2/APTS/Ru) was obtained after coordination and reduction of Ru3+ on the Fe3O4@SiO2/APTS nanocomposite. The Ru nanoparticles were not only ultra‐small with nearly monodisperse sizes but also had strong affinity with the surface of Fe3O4@SiO2/APTS. The obtained catalyst exhibited excellent catalytic performance for the hydrogenation of a variety of aromatic nitro compounds, even at room temperature. Moreover, Fe3O4@SiO2/APTS/Ru was easily recovered using a magnetic field and directly reused for at least five cycles without significant loss of its activity. 相似文献
19.
Yunxia Huang Shuaipeng Ge Xiaojuan Chen Zhongcheng Xiang Xinran Zhang Ruoxuan Zhang Yimin Cui 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(62):14117-14122
The design of electrode materials with rational core/shell structures is promising for improving the electrochemical properties of supercapacitors. Hence, hierarchical FeCo2S4@FeNi2S4 core/shell nanostructures on Ni foam were fabricated by a simple hydrothermal method. Owing to their structure and synergistic effect, they deliver an excellent specific capacitance of 2393 F g−1 at 1 A g−1 and long cycle lifespan as positive electrode materials. An asymmetric supercapacitor device with FeCo2S4@FeNi2S4 as positive electrode and graphene as negative electrode exhibited a specific capacitance of 133.2 F g−1 at 1 A g−1 and a high energy density of 47.37 W h kg−1 at a power density of 800 W kg−1. Moreover, the device showed remarkable cycling stability with 87.0 % specific-capacitance retention after 5000 cycles at 2 A g−1. These results demonstrate that the hierarchical FeCo2S4@FeNi2S4 core/shell structures have great potential in the field of electrochemical energy storage. 相似文献
20.
Chao He Mingyuan Li Jue Zhang Bingqing Yan Weifeng Zhao Shudong Sun Changsheng Zhao 《Macromolecular bioscience》2020,20(8)
Excessive bilirubin in the body of patient with liver dysfunction or metabolic obstruction may cause jaundice with irreversible brain damage, and new type of adsorbent for bilirubin is under frequent investigation. Herein, graphene oxide based core @ polyethersulfone‐based shell beads are fabricated by phase inversion method, amides and heparin‐like polymer are introduced to functionalize the core‐shell beads. The beads are successfully prepared with obvious core‐shell structure, adequate thermostability and porous shell. Clotting times and protein adsorption are investigated to inspect the hemocompatibility property of the beads. The adsorption of bilirubin is systematically investigated by evaluating the effects of contacting time, initial concentration and temperature on the adsorption, which exhibits improved bilirubin adsorption amount for the beads with amides contained cores or/and shells. It is worth believing that the amides and heparin‐like polymer co‐functionalized core‐shell beads may be utilized in the field of hemoperfusion for bilirubin adsorption. 相似文献