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21.
Spatial Micropatterning of Growth Factors in 3D Hydrogels for Location‐Specific Regulation of Cellular Behaviors 下载免费PDF全文
Growth factors are potent stimuli for regulating cell function in tissue engineering strategies, but spatially patterning their presentation in 3D in a facile manner using a single material is challenging. Micropatterning is an attractive tool to modulate the cellular microenvironment with various biochemical and physical cues and study their effects on stem cell behaviors. Implementing heparin's ability to immobilize growth factors, dual‐crosslinkable alginate hydrogels are micropatterned in 3D with photocrosslinkable heparin substrates with various geometries and micropattern sizes, and their capability to establish 3D micropatterns of growth factors within the hydrogels is confirmed. This 3D micropatterning method could be applied to various heparin binding growth factors, such as fibroblast growth factor‐2, vascular endothelial growth factor, transforming growth factor‐betas and bone morphogenetic proteins while retaining the hydrogel's natural degradability and cytocompability. Stem cells encapsulated within these micropatterned hydrogels have exhibited spatially localized growth and differentiation responses corresponding to various growth factor patterns, demonstrating the versatility of the approach in controlling stem cell behavior for tissue engineering and regenerative medicine applications. 相似文献
22.
Musun Kwak Jungwoo Park Jongho Jeon Kyoungri Kim Yoonseon Yi Donsik Choi Youngseok Choi Kyongdeuk Jeong 《Journal of the Society for Information Display》2011,19(9):576-582
Abstract— To understand the mechanism of the disclination defect of the liquid‐crystal (LC) phase, this study was conducted to directly analyze the polymer‐network (PN) structure of polymer‐stabilized blue phase (PSBP), which is minutely formed on all LC layers. The PN was examined after first removing the glass decap and then the LC. Important to note is that the removal of the glass decap did not affect or damage the PN structure. The PN was determined to be a stable structure without any change to the thickness of the layer. When removing the LC, both hexane and acetone solutions were used. Moreover, there was no structural deformation to the PN when using the hexane solution. The results of the study show that the actual size of the polymer chain is in fact 50–60 nm, five times larger than previous theories which estimated the size to be only 10 nm. In addition, this study confirmed that the pores between the PN are 100–200 nm. The PN structure was shown to be susceptible to change based on different heating temperatures. In summation, now that defect lines of a LC display (LCD) could be directly measured, further progress and development in the theoretical interpretations of the Kerr effect on PSBP can be realized. 相似文献
23.
HzKR127 is the humanized monoclonal antibody effective for the neutralization of human hepatitis B virus. By means of the free energy perturbation (FEP) calculations based on molecular dynamic (MD) simulations, we examine the mutation-induced variations in the energetic and structural features associated with the interactions between HzKR127 and its antigen. N58A, Y96A, D97A, and D97A/Y102A mutants of HzKR127 are taken in account in this study for which the experimental data for relative efficacies with respect to the wild-type antibody are available. The results of the present MD-FEP simulation studies show that in order to enhance the affinity for the antigen, the engineering of HzKR127 should be made in such a way as to promote the dynamic stability of the overall protein conformation and that of the translational motion of the antigen in the antibody-antigen complex. The relative binding free energies of the four mutant antibodies obtained from MD-FEP calculations compare pretty well with the experimental mutagenesis data with the associated squared correlation coefficient of 0.96. This indicates that MD-FEP calculations may serve as a useful computational tool for rational antibody engineering. Discussed in detail are the differences in the structural features of antibody-antigen interactions between the wild-type and the mutant antibodies that are responsible for the change in binding affinities for the antigen. 相似文献
24.
Sung Wook Kim Hyoung Sun Yoo Byoung‐Hwa Kwon Dong Seok Kang Minwon Suh Duk Young Jeon 《Journal of the Society for Information Display》2010,18(12):1104-1110
Abstract— In this study, organic wavelength‐converting films (WCFs) applied to InGaN blue LED‐based hybrid planar WLED has been fabricated. The organic dye layer in the WCF was formed between the upper and bottom polymer sheets by using a simple roll‐laminating technique. Subsequently, the hybrid planar WLEDs have been fabricated based upon these films. The luminous efficiency of green WCF‐based hybrid planar WLEDs with a single blue LED chip was 34.6 lm/W and that of red‐WCF‐assisted green WCF‐based hybrid planar WLEDs was 27.3 lm/W under 20 mA. The use of WCF to fabricate hybrid planar WLEDs showed better stability than that of directly coating organic color‐convergence materials (CCMs) on the LED chips. It only decreased to about 10% of the initial wavelength‐converting intensity after 1 hour of continual operation at 20 mA. 相似文献
25.
Musun Kwak Hanrok Chung Hyukmin Kwon Daekyung Han Yoonsun Yi Jongho Jeon Sangmun Lee Chulgu Lee Sooyeol Cha 《Journal of the Society for Information Display》2010,18(12):1072-1077
Abstract— The surface‐friction characteristics of the post‐bake temperature were compared to that of the rubbing condition on VA‐mode alignment films (AFs) using frictional force microscopy (FFM). The surface roughness and the surface frictional force increased when the temperature was elevated. However, the frictional asymmetry could not be detected by the frictional loop due to the instability of the side‐chain molecular arrangement. For the inter‐influences of the total friction and surface roughness, the density of the side chain was changed and it was intentionally rubbed for evaluation. The results showed that the total friction was higher when the rubbing was stronger and side‐chain density lower, and the surface roughness also increased in the same manner. This can be explained by the potential interaction due to the curved structure of the side‐chain surface that establishes the probe that is scanned and the top surface layer. In order to confirm the influence of the pre‐tilt angle on the tilt of the side chain, a test cell was produced under the same conditions and evaluated. The results showed that the pre‐tilt‐angle decreased according to the difference in density of the side chain and strength of rubbing after injecting liquid‐crystal (LC). 相似文献
26.
Sang‐Hee Ko Park Min‐Ki Ryu Sung‐Min Yoon Shinhyuk Yang Chi‐Sun Hwang Jae‐Hong Jeon 《Journal of the Society for Information Display》2010,18(10):779-788
Abstract— The stability of oxide TFTs has been the main focus of this research and is probably the most crucial requirement for the successful application to flat‐panel displays. Although the high Fermi level of oxide semiconductors makes TFTs basically stable under electrical stress, the device reliability under diverse variations of electrical stress is affected by materials such as active semiconductors and gate insulators, processes for the formation of back/front channels and passivation layers, and device configurations among other things. How these factors affect the device reliability have been investigated and a review of the stability is presented. In addition, several categories of the light instability of oxide TFTs is presented and the origin is discussed. 相似文献
27.
Processors in embedded systems mostly employ cache architectures in order to alleviate the access latency gap between processors and memory systems. Caches in embedded systems usually occupy a major fraction of the implemented chip area. The power dissipation of cache system thus constitutes a significant fraction of the power dissipated by the entire processor in embedded systems. In this paper, we propose the compressed tag architecture to reduce the power dissipation of the tag store in cache systems. We introduce a new tag-matching mechanism by using a locality buffer and a tag compression technique. The main power reduction feature of our proposal is the use of small tag space matching instead of full tag matching, with modest additional hardware costs. The simulation results show that the proposed model provides a power and energy-delay product reduction of up to 27.8% and 26.5%, respectively, while still providing a comparable level of system performance to regular cache systems. 相似文献
28.
Hyeon Bae Tae-Ryong Jeon Sungshin Kim Hyun-Soo Kim Dongseop Kim Seung-Soo Han Gary S. May 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2010,14(2):161-169
This study describes techniques for the cascade modeling and the optimization that are required to conduct the simulator-based
process optimization of solar cell fabrication. Two modeling approaches, neural networks and genetic programming, are employed
to model the crucial relation for the consecutively connected two processes in solar cell fabrication. One model (Model 1)
is used to map the five inputs (time, amount of nitrogen and DI water in surface texturing and temperature and time in emitter
diffusion) to the two outputs (reflectance and sheet resistance) of the first process. The other model (Model 2) is used to
connect the two inputs (reflectance and sheet resistance) to the one output (efficiency) of the second process. After modeling
of the two processes, genetic algorithms and particle swarm optimization were applied to search for the optimal recipe. In
the first optimization stage, we searched for the optimal reflectance and sheet resistance that can provide the best efficiency
in the fabrication process. The optimized reflectance and sheet resistance found by the particle swarm optimization were better
than those found by the genetic algorithm. In the second optimization stage, the five input parameters were searched by using
the reflectance and sheet resistance values obtained in the first stage. The found five variables such as the texturing time,
amount of nitrogen, DI water, diffusion time, and temperature are used as a recipe for the solar cell fabrication. The amount
of nitrogen, DI water, and diffusion time in the optimized recipes showed considerable differences according to the modeling
approaches. More importantly, repeated applications of particle swarm optimization yielded process conditions with smaller
variations, implying greater consistency in recipe generation. 相似文献
29.
Firms that have implemented knowledge management initiatives are now interested in nurturing voluntary knowledge sharing organizations, called communities of practice (CoPs). Adopting the Triandis model on attitude formation, we identified and validated a set of organizational factors that was anticipated to have effects on knowledge sharing by CoP members such as perceived consequences, affect, social factors and facilitating conditions. One hundred and seventy-nine members from 70 CoPs of a large multinational electronics firm participated in this survey. Based on the PLS analysis, perceived consequences, affect, social factors, and facilitating conditions were found to significantly affect knowledge sharing in CoPs. 相似文献
30.
Byung-Ho Jeon Marco Ajovalasit Joseph Giacomin 《International Journal of Industrial Ergonomics》2009,39(5):736-743
The aims of this study were to determine equal sensation curves for hand–arm steering wheel rotational vibration and to investigate the effect of gender on the subjective perceived intensity of steering wheel hand–arm vibration. Psychophysical response tests of 40 participants (20 males and 20 females) were performed using a steering wheel rotational vibration simulator using the category-ratio Borg CR10 scale procedure for direct estimation of perceived intensity. The test stimuli were sinusoidal vibrations at 22 third octave band centre frequencies in the range from 3 to 400 Hz, with acceleration amplitudes in the range from 0.04 to 27 m/s2 r.m.s. Multivariate regression procedures were applied to the experimentally acquired data in order to establish a regression model expressing the Borg CR10 perceived intensity values as a function of the two independent parameters of the frequency and amplitude of vibration. The equal sensation curves suggested a non-linear dependency of the subjective perceived intensity on both frequency and amplitude. Females were found to provide higher Borg CR10 perceived intensity values than males (p < 0.05), particularly at the higher intensity levels above approximately 1.0 m/s2 r.m.s and at the higher frequencies above approximately 20 Hz.