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991.
Focal adhesions play an important role in cell spreading,migration,and overall mechanical integrity.The relationship of cell structural and mechanical properties was investigated in the context of focal adhesion processes.Combined atomic force microscopy(AFM) and laser scanning confocal microscopy(LSCM) was utilized to measure single cell mechanics,in correlation with cellular morphology and membrane structures at a nanometer scale.Characteristic stages of focal adhesion were verified via confocal fluorescent studies,which confirmed three representative F-actin assemblies,actin dot,filaments network,and long and aligned fibrous bundles at cytoskeleton.Force-deformation profiles of living cells were measured at the single cell level,and displayed as a function of height deformation,relative height deformation and relative volume deformation.As focal adhesion progresses,single cell compression profiles indicate that both membrane and cytoskeleton stiffen,while spreading increases especially from focal complex to focal adhesion.Correspondingly,AFM imaging reveals morphological geometries of spherical cap,spreading with polygon boundaries,and elongated or polarized spreading.Membrane features are dominated by protrusions of 41-207 nm tall,short rods with 1-6 μm in length and 10.2-80.0 nm in height,and long fibrous features of 31-246 nm tall,respectively.The protrusion is attributed to local membrane folding,and the rod and fibrous features are consistent with bilayer decorating over the F-actin assemblies.Taken collectively,the reassembly of F-actin during focal adhesion formation is most likely responsible for the changes in cellular mechanics,spreading morphology,and membrane structural features. 相似文献
992.
A series of poly(ionic liquid)s (pILs) based on the 1‐vinyl‐3‐hexylimidazolium polymerizable cation and on the bis(trifluoromethylsulfonyl)imide, nonafluoro‐1‐butanesulfonate, dodecylbenzenesulfonate, heptadecafluorooctanesulfonate, and 4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11‐heptadecafluoroundecanoate anions have been synthesized and characterized. Their sorption/desorption response towards CO2 has been tested through quartz crystal microbalance investigations. The obtained results show that all of the pILs here reported are featured by peculiar CO2 sorption properties as they display fast and linear response, reversibility without any memory effect, and reproducibility, suggesting that anion plays a key role in determining sensitivity. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
993.
Baldo B Paganetti P Grueninger S Marcellin D Kaltenbach LS Lo DC Semmelroth M Zivanovic A Abramowski D Smith D Lotz GP Bates GP Weiss A 《Chemistry & biology》2012,19(2):264-275
Huntington's disease (HD) is an inherited neurodegenerative disorder caused by the amplification of a polyglutamine stretch at the N terminus of the huntingtin protein. N-terminal fragments of the mutant huntingtin (mHtt) aggregate and form intracellular inclusions in brain and peripheral tissues. Aggregates are an important hallmark of the disease, translating into a high need to quantify them in?vitro and in?vivo. We developed a one-step TR-FRET-based immunoassay to quantify soluble and aggregated mHtt in?cell and tissue homogenates. Strikingly, quantification revealed a decrease of soluble mHtt correlating with an increase of aggregated protein in primary neuronal cell cultures, transgenic R6/2, and HdhQ150 knock-in HD mice. These results emphasize the assay's efficiency for highly sensitive and quantitative detection of soluble and aggregated mHtt and its application in high-throughput screening and characterization of HD models. 相似文献
994.
A self-quenched zinc(ii) phthalocyanine dimer linked with an acid-sensitive ketal unit has been prepared, which can be activated in an acidic environment (pH = 5.0-6.5) as a result of the cleavage of the ketal linker and separation of the phthalocyanine units, resulting in enhanced fluorescence emission and singlet oxygen production. 相似文献
995.
This paper proposes an improved image coding scheme based on vector quantization. It is well known that the image quality
of a VQ-compressed image is poor when a small-sized codebook is used. In order to solve this problem, the mean value of the
image block is taken as an alternative block encoding rule to improve the image quality in the proposed scheme. To cut down
the storage cost of compressed codes, a two-stage lossless coding approach including the linear prediction technique and the
Huffman coding technique is employed in the proposed scheme. The results show that the proposed scheme achieves better image
qualities than vector quantization while keeping low bit rates. 相似文献
996.
?eljana Bona?i? Lo?i? 《Central European Journal of Physics》2012,10(1):172-180
We investigate the energy-loss function for a previously developed model of quasi-one-dimensional metals with two one-dimensional
electron bands per donor and acceptor chains and the three-dimensional long-range Coulomb electron-electron interaction within
the random phase approximation. It is essentially influenced by two hybridized collective modes which result from the strong
coupling of the intraband plasmon and the interband dipolar modes. Our calculations show that the spectral weights of the
renormalized plasmon and the dipolar mode dominate within the long wavelength limit, while for large longitudinal wave vectors
the intraband electron-hole quasi-continuumgains some experimentally observable spectral weight as the second mode approaches
it. The function obtained is brought into correspondence with the data of the quasi-one-dimensional organic conductor tetrathiafulvalene-tetracyanoquinodimethane
(TTF-TCNQ) obtained from electron energy-loss spectroscopy (EELS) measurements. 相似文献
997.
998.
Tzu-Chieh Lo Ling-Hsuan Tsai Chih-Hsien Cheng Po-Sheng Wang Yi-Hao Pai Chih-I Wu Gong-Ru Lin 《Journal of Non》2012,358(17):2126-2129
Amorphous silicon quantum dots (Si-QDs) self-aggregated in silicon-rich silicon carbide are synthesized by growing with plasma-enhanced chemical vapor deposition on (100)-oriented Si substrate. Under the environment of Argon (Ar)-diluted Silane (SiH4) and pure methane (CH4), the substrate temperature and RF power are set as 350 °C and 120 W, respectively, to provide the Si-rich SiC with changing fluence ratio (R = [CH4 ]/[SiH4] + [CH4]). By tuning the fluence ratio from 50% to 70%, the composition ratio x of Si-rich Si1 ? xCx film is varied from 0.27 to 0.34 as characterized by X-ray photoelectron spectroscopy (XPS), which reveals the component of Si2p decreasing from 66.3 to 59.5%, and the component of C1s increasing from 23.9% to 31% to confirm the formation of Si-rich SiC matrix. Annealing of the SiC sample from 650 °C to 1050 °C at 200 °C increment for 30 min induces the very tiny shift on the wavenumber of the crystalline Si (c-Si) related peak due to the precipitation of Si-QDs within the SiC matrix, and the Raman scattering spectra indicate a broadened Raman peak ranging from 410 to 520 cm? 1 related to the amorphous Si accompanied with the significant enhancement for SiC bond related peak at 980 cm? 1. From the high resolution transmission electron microscopy images, the critical temperature for Si-QD precipitation is found to be 850 °C. The self-assembly of the crystallized Si-QDs with the size of 3 ± 0.5 nm and the volume density of (3 ± 1) × 1018 (#/cm3) in Si-rich SiC film with R = 70% are observed after annealing at higher temperature. 相似文献
999.
1000.
Based on the microscopic two velocity difference model, a macroscopic model called speed viscous continuum model is developed to describe traffic flow. The relative velocities are added to the motion equation, which leads to viscous effects in continuum model. The viscous continuum model overcomes the backward travel problem, which exists in many higher-order continuum models. Nonlinear analysis shows that the density fluctuation in traffic flow leads to density waves. Near the onset of instability, a small disturbance could lead to solitons described by the Korteweg-de Vries-Burgers (KdV-Burgers) equation, which is seldom found in other traffic flow models, and the soliton solution is derived. 相似文献