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991.
992.
Jia‐Wei Li Yu‐Jing Chiu Chia‐Jui Chang Hung‐Chieh He Yi‐Hsuan Tu Kuan‐Ting Lin Yu‐Liang Lin Tzu‐Hsun Kao Hsun‐Hao Hsu Hsiao‐Fan Tseng Tien‐Chang Lu Jiun‐Tai Chen 《大分子材料与工程》2020,305(1)
Polyimides (PIs) possess excellent mechanical properties, thermal stability, and chemical resistance and can be converted to carbon materials by thermal carbonization. The preparation of carbon nanomaterials by carbonizing PI‐based nanomaterials, however, has been less studied. In this work, the fabrication of PI nanofibers is investigated using electrospinning and their transformation to carbon nanofibers. Poly(amic acid) carboxylate salts (PAASs) solutions are first electrospun to form PAAS nanofibers. After the imidization and carbonization processes, PI and carbon nanofibers can then be obtained, respectively. The Raman spectra reveal that the carbon nanofibers are partially graphitized by the carbonization process. The diameters of the PI nanofibers are observed to be smaller than those of the PAAS nanofibers because of the formation of the more densely packed structures after the imidization processes; the diameters of the carbon nanofibers remain similar to those of the PI nanofibers after the carbonization process. The thermal dissipation behaviors of the PI and carbon nanofibers are also examined. The infrared images indicate that the transfer rates of thermal energy for the carbon nanofibers are higher than those for the PI nanofibers, due to the better thermal conductivity of carbon caused by the covalent sp2 bonding between carbon atoms. 相似文献
993.
Chunfa Ouyang Chao Zhao Wei Li Xiuchun Wu Xiaoxia Le Tao Chen Wei Huang Qun Gao Xiaoqian Shan Rei Zhg Weiping Zhang 《大分子材料与工程》2020,305(6)
Self‐healing polymer materials have attracted extensive attention and have been explored due to their ability of crack repairing in materials. This paper aims to develop a novel polyurethane‐based material with high self‐healing efficiency and excellent mechanical properties under 80 °C on the basis of reversible Diels–Alder bonds as well as zinc–ligand structure (DA‐ZN‐PU). By integrating DA bonds and zinc–ligand structure, as‐prepared DA‐ZN‐PU samples reach the maximum tensile strength as much as 28.45 MPa. After self‐healing, the tensile strength is 25.85 MPa, leading to the high self‐healing efficiency of 90.8%. In addition, by introducing carbonyl iron powder (CIP), a new polyurethane containing carbonyl iron powder (DA‐ZN‐CIP‐PU) can be achieved, exhibiting microwave‐assisted self‐healing property. And the self‐healing efficiency can be reached to 92.6% in 3 min. Due to high self‐healing efficiency and excellent mechanical properties of the prepared novel polyurethane, it has application attributes in crack repair of functional composite materials. 相似文献
994.
Yinhua Jiang ZhiYuan Peng Shuaibin Zhang Fan Li Zhanchao Liu Jianming Zhang Yan Liu Kun Wang 《Ceramics International》2018,44(6):6115-6126
The design and construction of efficient visible light responsive composite photocatalysts with intimate interfacial contacts in photocatalytic field have attracted huge interest. Herein, a double-shelled ZnIn2S4 nanosheets/TiO2 hollow composite single nanosphere (ZIS/TiO2) was first fabricated by a facile hydrothermal process, where 2D ZnIn2S4 nanosheets self-assembled on the external surface of TiO2 hollow nanosphere to form the double-shelled hollow single sphere. The morphologies, structures, optical properties of as-prepared double-shelled ZIS/TiO2 hollow nanospheres were characterized in detail. The photocatalytic activities of double-shelled ZIS/TiO2 nanospheres for the photodegradations of Tetracycline hydrochloride, Levofloxacin and Rhodamine B under visible light irradiation have been investigated. Compared to pure TiO2 and ZnIn2S4, the obtained ZIS/TiO2 samples have significantly improved photocatalytic performances. The most optimal photocatalytic activity of ZIS/TiO2-2 nanocomposite with 64 wt% ZnIn2S4 nanosheets coated is observed, and its degradation rate constant is 2.32 and 2.14 times as high as those of pure TiO2 and ZnIn2S4. The superior photocatalytic performance of ZIS/TiO2 nanocomposite can be ascribed to its unique double shell hollow structure and the synergistic effect between ZnIn2S4 and TiO2. Our result provides some guidance for designing novel morphologies of composite photocatalyst with good photocatalytic performance. 相似文献
995.
José M. León Blanco Pedro L. González-R Carmen Martina Arroyo García María José Cózar-Bernal Marcos Calle Suárez David Canca Ortiz 《Drug development and industrial pharmacy》2018,44(1):135-143
This work was aimed at determining the feasibility of artificial neural networks (ANN) by implementing backpropagation algorithms with default settings to generate better predictive models than multiple linear regression (MLR) analysis. The study was hypothesized on timolol-loaded liposomes. As tutorial data for ANN, causal factors were used, which were fed into the computer program. The number of training cycles has been identified in order to optimize the performance of the ANN. The optimization was performed by minimizing the error between the predicted and real response values in the training step. The results showed that training was stopped at 10?000 training cycles with 80% of the pattern values, because at this point the ANN generalizes better. Minimum validation error was achieved at 12 hidden neurons in a single layer. MLR has great prediction ability, with errors between predicted and real values lower than 1% in some of the parameters evaluated. Thus, the performance of this model was compared to that of the MLR using a factorial design. Optimal formulations were identified by minimizing the distance among measured and theoretical parameters, by estimating the prediction errors. Results indicate that the ANN shows much better predictive ability than the MLR model. These findings demonstrate the increased efficiency of the combination of ANN and design of experiments, compared to the conventional MLR modeling techniques. 相似文献
996.
Jingshuai Yang Yihan Wang Guohao Yang Sifan Zhan 《International Journal of Hydrogen Energy》2018,43(17):8464-8473
The blend polymer membranes were synthesized from the methylimidazolium poly (aromatic ether ketone) (MeIm-PAEK) and fluoropolymers (PVDF and PVDF-HFP) with excellent thermal stability and improved dimensional stabilities for high-temperature polymer electrolyte fuel cells. The MeIm-PAEK exhibited good compatibility with PVDF or PVDF-HFP without phase separation. High phosphoric acid doping contents of the blend membranes were achieved at elevated temperatures with acceptable swellings. The acid doped blend membranes displayed lower dimensional swellings and higher mechanical strength compared to the MeIm-PAEK membrane, which allowed the blend membranes to obtain higher acid doping contents and proton conductivities. The MeIm-PAEK/10%PVDF membrane with a phosphoric acid doping content of 700 wt% showed a proton conductivity as high as 0.192 S cm?1 at 180 °C under the non-humidified condition and a tensile strength of 4.3 MPa at room temperature. 相似文献
997.
Effect of high‐pressure processing on immunoreactivity,microbial and physicochemical properties of hazelnut milk 下载免费PDF全文
Min‐Ju Tsai Ming‐Ching Cheng Bang‐Yuan Chen Chung‐Yi Wang 《International Journal of Food Science & Technology》2018,53(7):1672-1680
This study investigated the effects of high‐pressure processing (HPP) and thermal processing (TP) on the overall quality attributes of hazelnut milk. HPP achieved the same microbial safety as TP, and the pH, °Brix and sugar contents were maintained at the levels of fresh hazelnut milk. Although HPP caused colour changes, the ?E was smaller than that of the TP sample. Increasing pressure significantly decreased the immunoreactivity of the hazelnut milk by 70%, while simultaneously reducing the levels of essential and non‐essential amino acids and chemical score (CS) and the essential amino acid index (EAAI) values. However, neither HPP nor TP significantly affected the fatty acid composition of hazelnut milk. HPP retained higher total phenolic and flavonoid levels of the hazelnut milk, with a better antioxidant capacity than TP samples. Thus, the HPP maintained microbial safety during cold storage, and physicochemical properties of the treated hazelnut milk were not significantly different from those of the fresh hazelnut milk. 相似文献
998.
Two network models with multiple derivative couplings and different dimensions of output and input vectors are investigated in this paper. The problem of passivity for the proposed network models is analysed by utilising some inequality techniques and Lyapunov functional method, and several synchronisation conditions for complex dynamical networks with multiple derivative couplings (CDNMDC) are given. Moreover, by employing adaptive state feedback control strategy, some sufficient conditions for guaranteeing passivity and synchronisation of CDNMDC are obtained. In the end, we give two examples to verify the effectiveness of the results. 相似文献
999.
为了解决高温气冷堆示范工程(HTR-PM)无测量杆螺柱预紧力的控制问题,保证反应堆一回路压力边界的法兰密封,需要对无测量杆螺柱的预紧力进行标定。以HTR-PM中 M56无测量杆螺柱为例,采用液压拉伸机对其进行标定试验,找到螺栓拉伸机拉伸预紧力与螺柱残余预紧力的关系曲线;分析了螺栓拉伸机拉伸前后导致螺柱残余预紧力下降的原因,再通过材料力学本构关系,建立了螺栓拉伸机拉紧力与螺柱回弹后残余预紧力的理论关系式。结果表明,试验获得的螺柱联接体系中的残余预紧力及螺母旋紧前的预紧力关系式都与理论分析比较接近;螺栓拉伸机相同出力下,实际设备管嘴法兰螺柱的残余预紧力会比标定值大,但这更有利于法兰面的密封。 相似文献
1000.