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171.
172.
Preparation and characterization of methoxy‐poly(ethylene glycol) side chain grafted onto chitosan as a wound dressing film
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Cheng‐Han Yang Szu‐Hsien Chen Yun‐Wen Pan Ching‐Nan Chuang Wen‐Chi Chao Tai‐Horng Young Wen‐Yen Chiu Chih‐Kuang Wang Kuo‐Huang Hsieh 《应用聚合物科学杂志》2015,132(31)
Chitosan has received extensive attention as a biomedical material; however, the poor solubility of chitosan is the major limiting factor in its utilization. In this study, chitosan‐based biomaterials with improved aqueous solubility were synthesized. Two molecular weights (750 Da and 2000 Da) of methoxypoly(ethylene glycol) (mPEG) were grafted onto chitosan (mPEG‐g‐chitosan) to form a ~100‐μm‐thick plastic film as a wound dressing. The chemical structures of the mPEG‐g‐chitosan copolymers were confirmed using Fourier transform infrared spectroscopy (FTIR), and the thermal properties were characterized using thermogravimetry analysis (TGA). Their microstructures were observed using scanning electron microscopy (SEM). The other properties were analyzed via the swelling ratio, tensile strength, elongation, and water vapor transmission rate (WVTR). Biocompatibility evaluations through biodegradability, cytotoxicity, and antimicrobial effect studies were also performed. The obtained mPEG‐g‐chitosan copolymers were soluble in slightly acidic aqueous solutions (pH~6.5) at a concentration of 10 wt %. The optimal mPEG‐g‐chitosan hydrogels had swelling ratios greater than 100% and WVTRs greater than 2000 g/m2/day. Their performance against Staphylococcus aureus will be subjected to further improvements with respect to medical applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42340. 相似文献
173.
Planar Heterojunction Perovskite Solar Cells Incorporating Metal–Organic Framework Nanocrystals
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174.
Ming‐Shu Kuo Shinn‐Jen Chang Ping‐Hsun Hsieh Yuan‐Chang Huang Chia‐Chen Li 《Journal of the American Ceramic Society》2016,99(2):445-451
This article discusses the appropriate dispersant for titania (TiO2) nanopowder in organic‐based suspensions. Four types of oleyl‐based dispersants, namely, oleyl alcohol, oleic acid, oleylamine, and oleyl phosphate, which have the functional groups hydroxyl (–OH), carboxyl (–COOH), amino (–NH2), and phosphorous [–P(=O)(OH)2], respectively, were compared for their ability to disperse TiO2. Experimental results for zeta potential, adsorption, FT‐IR spectroscopy, and rheology, as well as theoretical calculations, indicate that dispersants with –P(=O)(OH)2 and –NH2 were more efficient than those with –COOH or –OH. The primary reason for this difference is related to the different interactions of TiO2 with various dispersants and to different dispersion mechanisms. In addition to the major functional groups, –OH in the chemical structure of dispersants was important, as it might have other effects such as destabilization of the suspensions. 相似文献
175.
New Perspectives on the Gas–Solid Reaction of α‐Si3N4 Powder in Wet Air at High Temperature
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Enhui Wang Junhong Chen Xiaojun Hu Kuo‐Chih Chou Xinmei Hou 《Journal of the American Ceramic Society》2016,99(8):2699-2705
The reaction behavior of chemically vapor‐deposited silicon nitride (α‐Si3N4) powder in wet air at 1673–1873 K for 10 h has been investigated. The oxidation and volatilization reaction coexist initially while volatilization reaction progressively becomes the limiting step with extended reaction time. Based on the experimental curves, a new kinetic model regarding both solid product layer and hypothetically volatile product layer has been developed to interpret its short‐term reaction and predict long‐term corrosion behavior. The calculated results agree well with the experimental data. Predictably, this new kinetic model can not only be used to treat the reaction of Si3N4 powder in wet air but also can be applied to deal with the gas–solid reaction of other ceramic powders. 相似文献
176.
Ying-Hsien Huang Ho-Chang Kuo Fu-Chen Huang Hong-Ren Yu Kai-Sheng Hsieh Ya-Ling Yang Jiunn-Ming Sheen Sung-Chou Li Hsing-Chun Kuo 《International journal of molecular sciences》2016,17(5)
Kawasaki disease (KD) is a type of systemic vasculitis that primarily affects children under the age of five years old. For sufferers of KD, intravenous immunoglobulin (IVIG) has been found to successfully diminish the occurrence of coronary artery lesions. Anemia is commonly found in KD patients, and we have shown that in appropriately elevated hepcidin levels are related to decreased hemoglobin levels in these patients. In this study, we investigated the time period of anemia and iron metabolism during different stages of KD. A total of 100 patients with KD and 20 control subjects were enrolled in this study for red blood cell and hemoglobin analysis. Furthermore, plasma, urine hepcidin, and plasma IL-6 levels were evaluated using enzyme-linked immunosorbent assay in 20 KD patients and controls. Changes in hemoglobin, plasma iron levels, and total iron binding capacity (TIBC) were also measured in patients with KD. Hemoglobin, iron levels, and TIBC were lower (p < 0.001, p = 0.009, and p < 0.001, respectively) while plasma IL-6 and hepcidin levels (both p < 0.001) were higher in patients with KD than in the controls prior to IVIG administration. Moreover, plasma hepcidin levels were positively and significantly correlated with urine hepcidin levels (p < 0.001) prior to IVIG administration. After IVIG treatment, plasma hepcidin and hemoglobin levels significantly decreased (both p < 0.001). Of particular note was a subsequent gradual increase in hemoglobin levels during the three weeks after IVIG treatment; nevertheless, the hemoglobin levels stayed lower in KD patients than in the controls (p = 0.045). These findings provide a longitudinal study of hemoglobin changes and among the first evidence that hepcidin induces transient anemia and hypoferremia during KD’s acute inflammatory phase. 相似文献
177.
178.
Toward multiple maximum power point estimation of photovoltaic systems based on semiconductor theory
Jen‐Cheng Wang Yu‐Li Su Kun‐Chang Kuo Jyh‐Cherng Shieh Joe‐Air Jiang 《Progress in Photovoltaics: Research and Applications》2015,23(7):847-861
Environmental conditions, such as temperature, non‐uniform irradiation, and solar shading, deeply affect the characteristics of photovoltaic (PV) modules in PV‐assisted generation systems. Several local maximum power points (MPPs) are found in the power–voltage curve of PV systems constructed by series/parallel‐connected PV modules under partially shaded conditions. The characteristics of PV systems change unpredictably when multiple MPPs occur, so the actual MPP tracking (MPPT) becomes a difficult task. Conventional MPPT methods for the PV systems under partially shaded conditions cannot quickly find the actual MPP such that the optimal utilization of PV systems cannot be achieved. Based on the p–n junction semiconductor theory, we develop a multipoint direct‐estimation (MPDE) method to directly estimate the multiple MPPs of the PV systems under partially shaded conditions and to cope with the mentioned difficulties. Using the proposed MPDE method, the multiple MPPs of the PV systems under partially shaded conditions can be directly determined from their irradiated current–voltage and power–voltage characteristic curves. The performances of the proposed MPDE method are evaluated by examining the characteristics of multiple MPPs of PV systems with respect to different shading strengths and numbers of the shaded PV modules and also tested using the field data. The experimental results demonstrate that the proposed MPDE method can simply and accurately estimate the multiple MPPs of the PV systems under partially shaded conditions. The optimization of MPP control models and the MPPT for PV systems could be achieved promisingly by applying the proposed method. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
179.
拉曼光谱经过基线校正处理后,运用子空间模式识别原理,反应物水杨酸、醋酸酐以及催化剂氨基磺酸的拉曼光谱作为子空间,各个反应时刻的拉曼光谱作为被关注向量,求取被关注与子空间夹角,通过时间序列分析模型对空间向量夹角变动分析体系内组分变化情况设经验阀值δ(ti)小于0.5判定为反应终点,此时水杨酸的转化率为97.8%。 相似文献
180.
Poly(ethylene terephthalate)/poly(ethylene glycol‐co‐1,3/1,4‐cyclohexanedimethanol terephthalate)/clay nanocomposites: Mechanical properties,optical transparency,and barrier properties
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Poly(ethylene terephthalate) (PET)/clay, PET/poly(ethylene glycol‐co‐1,3/1,4‐cyclohexanedimethanol terephthalate) (PETG), and PET/PETG/clay nanocomposites were fabricated using the twin‐screw extrusion technique. The spherulitic morphologies, thermomechanical, mechanical, and gas‐barrier properties, as well as the effect of clay on the transparency of the resulting nanocomposites were identified. The clay induced the heterogeneous nucleation of the nanocomposites during the cold crystallization process, thereby increasing the crystallinities and melting temperatures of the resulting nanocomposites. The incorporation of clay increased the storage moduli, Young's moduli, impact strengths, and barrier properties of the PET, PETG, and PET/PETG blend. Regarding the optical transparency, the inclusion of clay can make the crystallizable PET matrix crystalline opaque. However, the amorphous PETG maintained its transparency. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39869. 相似文献