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81.
N‐(2‐hydroxy)propyl‐3‐trimethylammonium chitosan chloride (HTCC), a water‐soluble chitosan quaternary ammonium derivative, was used as an antimicrobial agent for cotton fabrics. HTCC has a lower minimum inhibition concentration (MIC) against Staphylococcus aureus, Klebsiella pneumoniae, and Escherichia coli compared to that of chitosan; however, the imparted antimicrobial activity is lost on laundering. Thus crosslinking agents were utilized to obtain a durable antimicrobial treatment by immobilizing HTCC. Several crosslinkers such as dimethyloldihydroxyethylene urea (DMDHEU), butanetetracarboxylic acid (BTCA), and citric acid (CA) were used with HTCC to improve the laundering durability of HTCC treatment by covalent bond formation between the crosslinker, HTCC and cellulose. The polycarboxylic acid treatment was superior to the DMDHEU treatment in terms of prolonged antimicrobial activity of the treated cotton after successive laundering. Also, the cotton treated with HTCC and BTCA showed improved durable press properties without excessive deterioration in mechanical strength or whiteness when compared to the citric acid treatment. With the addition of only 0.1% HTCC to BTCA solutions, the treated fabrics showed durable antimicrobial activity up to 20 laundering cycles. The wrinkle recovery angle and strength retention of the treated fabrics were not adversely affected with the addition of HTCC. Therefore, BTCA can be used with HTCC in one bath to impart durability of antimicrobial activity along with durable press properties to cotton fabric. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1567–1572, 2003 相似文献
82.
Styrene‐acrylonitrile copolymer (SAN)/clay nanocomposites were synthesized through an emulsion copolymerization of styrene and acrylonitrile in the presence of sodium montmorillonite, and their physical properties and electroresponsiveness under an applied electric field were characterized. Thermogravimetric analysis (TGA) showed that the thermal stability of the synthesized polymer was sustained. X‐ray diffraction (XRD) analysis confirmed the insertion of SAN into the interlayers of clay, whose separation consequently increased, as compared to those of the pristine clay. Transmission electron microscopy (TEM) was used to observe the suspended state of clay. Dry‐base electrorheological (ER) fluids were prepared by mixing intercalated SAN nanocomposite particles into silicone oil. Typical ER behavior, i.e., enhancement of shear and yield stresses in the presence of an applied electric field, was observed using a rotational rheometer equipped with a high‐voltage generator. A universal yield stress scaling equation was also found to fit our experimental data well. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 821–827, 2003 相似文献
83.
Chan-Geun Song Jonghan Won Inhoon Jang Hyeunseok Choi 《Journal of the American Ceramic Society》2021,104(9):4398-4407
In metal oxide nanofiber fabrication using the electrospinning method, heat treatment is performed at temperatures of 500°C or higher for crystallization and polymer desorption. Therefore, it is difficult to fabricate low-temperature phase metal oxides that crystallize at low temperatures. TiO2, a representative metal oxide often used as photocatalysts, is known to have higher photocatalytic activity in the low-temperature phase (anatase structure) than in the high-temperature phase (rutile structure). Studies on the fabrication of TiO2 anatase nanofibers using conventional electrospinning have reported disadvantages such as the partial expression of rutile structures and low crystallinity. This study developed an anatase TiO2 nanofiber as a high-efficiency catalyst based on the electrospinning method and a residual organic matter cleaning method that employs ultra-violet (UV) light. We fabricated nanofibers using the electrospinning method and implemented TiO2 nanofibers with the anatase structure through heat treatment at 260°C. Residual organics remaining after heat treatment of the fabricated crystalized TiO2 nanofibers were removed by exposing them to UV light, thereby improving photocatalytic efficiency. The photocatalytic efficiency of the fabricated TiO2 nanofibers was confirmed through a methylene blue (MB) decomposition experiment under visible light irradiation. The photocatalytic efficiency (time taken for the concentration of the MB solution to reach 50%) of the UV-treated TiO2 nanofibers was approximately six times higher than of P25 and the heat-treated nanofibers. 相似文献
84.
Hyunjun Kim Brahim Akdim James Park Woo-Yong Jang Randall S. Hay Augustine M. Urbas Christopher Woodward 《Journal of the American Ceramic Society》2021,104(11):5659-5670
High-throughput computation, based on density functional theory (HT-DFT), is used to predict the bounds for optical transparency, from the ultraviolet to the infrared, for materials in the pyrochlore family. The HT-DFT approach adopted here uses an initial screening from Materials-Project database, with millions of calculated properties. Band gaps and phonon spectra were calculated from selected pyrochlore crystal structures taken from the Materials Project database. Short and long wavelength bounds for optical transparency were calculated for chemistries with stable, cubic structures. The calculations predict that La2Ce2O7 has one of the broadest range of transparency for the pyrochlore family. Based on these calculations, dense polycrystalline samples of La2Ce2O7 were produced by sintering and hot-isostatic pressing. Transparency was characterized by methods that did not require large samples with high optical quality, obtaining 7.15 and 7.5 µm at 95% and 90% normalized transmittance, respectively. Bandgap calculations suggest a lower bound of UV transparency cut-off of 0.3 µm. The infrared wavelength cut-off is higher than that reported for other pyrochlores, and higher than for yttria, zirconia, or other common infrared transparent ceramics. We discuss our prediction and characterization methods as well as the suitability of pyrochlores for mid- and far-infrared optical applications. 相似文献
85.
Ji-Won Jang Jae-Hyong Park Il-Jin Kim Jae-Hak Sim Seung-gun Yu Dong-Jin Lee Young-Hee Lee Sang-Hui Park Han-Do Kim 《应用聚合物科学杂志》2021,138(6):49788
In this study, a series of thermoresponsive cross-linked copolymer poly [N-isopropylacrylamide(NIPAm)-co-N-isopropylmethacrylamide(NIPMAm)] (P-M series samples: P-M-0, 10, 20, 30, 40, where numbers are co-monomer contents) hydrogels were prepared by free radical polymerization using the main monomer N-isopropylacrylamide (NIPAm), co-monomer N-isopropylmethacrylamide (NIPMAm), cross-linking agent N, N-methylenebisacrylamide, initiator (ammonium persulfate)/catalyst, and solvent water. In addition, a series of samples [P-G series samples: P-G-0, 10, 20, 30, 40, where numbers are co-solvent glycerol content) were prepared using P-M-40 as components and water/co-solvent glycerol as a mixed solvent. The effects of co-monomer NIPMAm and co-solvent glycerol contents on the lower critical solution temperature (LCST)/freezing temperature and light transmittance as function of temperature of the prepared copolymer gels were investigated. The resulting thermoresponsive polymer gels had LCSTs in the range of 17.9 to 38.7°C and freezing points in the range of 6.3 to −38.5°C. These gels are suitable materials for smart windows that are responsive to various environmental conditions. 相似文献
86.
This paper presents a visual object tracking system which is tolerant to external imaging factors such as illumination, scale, rotation, occlusion and background changes. Specifically, an integration of an online version of total-error-rate minimization based projection network with an observation model of particle filter is proposed to effectively distinguish between the target object and the background. A re-weighting technique is proposed to stabilize the sampling of particle filter for stochastic propagation. For self-adaptation, an automatic updating scheme and extraction of training samples are proposed to adjust to system changes online. Our qualitative and quantitative experiments on 16 public video sequences show convincing performances in terms of tracking accuracy and computational efficiency over competing state-of-the-art algorithms. 相似文献
87.
88.
Su-gil Cho Junyong Jang Shinyu Kim Sanghyun Park Tae Hee Lee Minuk Lee Jong-Su Choi Hyung-Woo Kim Sup Hong 《Structural and Multidisciplinary Optimization》2016,54(6):1671-1688
Uncertainty-based multidisciplinary design optimization (UMDO) has been widely acknowledged as an advanced methodology to address competing objectives and reliable constraints of complex systems by coupling relationship of disciplines involved in the system. UMDO process consists of three parts. Two parts are to define the system with uncertainty and to formulate the design optimization problem. The third part is to quantitatively analyze the uncertainty of the system output considering the uncertainty propagation in the multidiscipline analysis. One of the major issues in the UMDO research is that the uncertainty propagation makes uncertainty analysis difficult in the complex system. The conventional methods are based on the parametric approach could possibly cause the error when the parametric approach has ill-estimated distribution because data is often insufficient or limited. Therefore, it is required to develop a nonparametric approach to directly use data. In this work, the nonparametric approach for uncertainty-based multidisciplinary design optimization considering limited data is proposed. To handle limited data, three processes are also adopted. To verify the performance of the proposed method, mathematical and engineering examples are illustrated. 相似文献
89.
Yongmin Park Jang Jin Yoo Dongwoo Kang Sungjin Kim 《Journal of the Society for Information Display》2015,23(9):391-396
We present a feasible modeling method to estimate the proper curvature for large‐sized curved TVs. We especially focused on two factors – preference and perceived distortion – to be considered to determine the proper curvature. The preference includes a number of advantages that people expect to fulfill the possibilities of a more immersive image and sense of realism from curved display. On the other hand, the perceived distortion means the side effects that people can notice uncomfortable feeling caused by the shape of a curved one. In order to find out how two factors would be different as a number of conditions like curvature, size, and viewing angle change, a series of subjective assessments were conducted. The evaluation results show that both the preference and perceived distortion vary with the conditions considerably. We performed the statistical analysis based on the results and proposed the quantification model of proper curvature, which has higher preference and less perceived distortion, for various‐sized curved TVs. 相似文献
90.
Tae Y. Jung Hong Jang Jay H. Lee 《International Journal of Control, Automation and Systems》2015,13(2):410-418
Model predictive control (MPC)-based approach to fab-wide scheduling has been suggested to solve constraint-aware production optimization and in-process inventory level control simultaneously at each scheduling instance. However, application of this approach to real fab suffers from computational difficulties brought by the need to solve a huge optimization problem on-line as real fab scheduling problems are characterized by long cycle times, multiple product types, hundreds of machines/processing steps and re-entrant product flows. This study explores the use of an offset-blocking strategy combined with a modified recursive least square (RLS) estimation in the fab-wide scheduler, in order to alleviate the difficulty. The strategy is tested on a modified version of published case study called Intel Mini-Fab (IMF) problem. Despite its simplicity, the blocking strategy showed excellent performance in the face of realistic demand changes and plant/model mismatch. 相似文献