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141.
Deconstructing the Effects of Matrix Elasticity and Geometry in Mesenchymal Stem Cell Lineage Commitment 下载免费PDF全文
Greg M. Harris Maria E. Piroli Ehsan Jabbarzadeh 《Advanced functional materials》2014,24(16):2396-2403
A wide variety of environmental factors including physical and biochemical signals are responsible for stem cell behavior and function. In particular, matrix elasticity and cell shape have been shown to determine stem cell function, yet little is known about the interplay between how these physical cues control cell differentiation. For the first time, by using ultraviolet (UV) lithography to pattern poly(ethylene) glycol (PEG) hydrogels, it is possible to manufacture microenvironments capable of parsing the effects of matrix elasticity, cell shape, and cell size in order to explore the relationship between matrix elasticity and cell shape in mesenchymal stem cell (MSC) lineage commitment. These data show that cells cultured on 1000 μm2 circles, squares, and rectangles are primarily adipogenic lineage regardless of matrix elasticity, while cells cultured on 2500 and 5000 μm2 shapes more heavily depend on shape and elasticity for lineage specification. It is further characterized how modifying the cell cytoskeleton through pharmacological inhibitors can modify cell behavior. By showing MSC lineage commitment relationships due to physical signals, this study highlights the importance of cell shape and matrix elasticity in further understanding stem cell behavior for future tissue engineering strategies. 相似文献
142.
Two sequences of operations necessary for implementation of high resolution image formation in strip and spotlight modes of the synthetic aperture radar (SAR) are presented. The sequences are mapped onto a mesh-connected SIMD architecture. The mapping includes not only parallel implementation of all the basic computation steps, but also all the necessary data transformation and communication operations. Detailed estimates of the processing times are provided for Hughes Research Laboratories Systolic/Cellular architecture.This work was partially supported by NSF grant No MIP-8714689 相似文献
143.
Eric S. Windsor Robert A. Carlton Greg Gillen Scott A. Wight David S. Bright 《Journal of research of the National Institute of Standards and Technology》2002,107(6):663-679
Copper oxide has been detected in the copper containing alloys of NBS Standard Reference Material (SRM) 482. This occurrence is significant because it represents heterogeneity within a standard reference material that was certified to be homogeneous on a micrometer scale. Oxide occurs as elliptically to spherically shaped precipitates whose size differs with alloy composition. The largest precipitates occur in the Au20-Cu80 alloy and range in size from submicrometer up to 2 μm in diameter. Precipitates are observed using light microscopy, electron microscopy, and secondary ion mass spectrometry (SIMS). SIMS has demonstrated that the precipitates are present within all the SRM 482 wires that contain copper. Only the pure gold wire is precipitate free. Initial results from the analysis of the Au20-Cu80 alloy indicate that the percentage of precipitates is less than 1 % by area. Electron probe microanalysis (EPMA) of large (2 μm) precipitates in this same alloy indicates that precipitates are detectable by EPMA and that their composition differs significantly from the certified alloy composition. The small size and low percentage of these oxide precipitates minimizes the impact that they have upon the intended use of this standard for electron probe microanalysis. Heterogeneity caused by these oxide precipitates may however preclude the use of this standard for automated EPMA analyses and other microanalysis techniques. 相似文献
144.
Ryan K. Roeder Greg A. Steinlage Kevin P. Trumble Keith J. Bowman 《Journal of the American Ceramic Society》1995,78(9):2367-2373
Dilute, dispersed, multicomponent suspensions containing Ce-ZrO2 , Al2 O3 , and varying Al2 O3 -platelet contents were centrifugally consolidated. Despite the favorable conditions for segregation, phase and size segregation did not occur in the highest Al2 O3 -platelet content suspension. The suspension properties did not consist of agglomeration, high solids fractions, or high suspension viscosities typically attributed with segregation prevention. Thus, a new mechanism is suggested, considering the effects of hydrodynamic particle interactions (interference drag or "drafting") on particle arrangement during consolidation. Particle drafting is proposed and supported as a mechanism for preventing segregation, and the importance of hydrodynamic particle interactions in ceramic processing is discussed. 相似文献
145.
Jun Li Greg Baird Yi‐Hsin Lin Hongwen Ren Shin‐Tson Wu 《Journal of the Society for Information Display》2005,13(12):1017-1026
Abstract— Refractive indices of two photocurable polymers, NOA65 and NOA81 (Norland Optical Adhesive), and two series of Merck liquid crystals, E‐series (E44, E48, and E7) and BL‐series (BL038, BL003 and BL006), and two UCF high‐birefringence liquid‐crystal mixtures were measured using an Abbe refractometer in the visible spectral region and 15–55°C temperature range. Some liquid crystals have excellent index matching with NOA65 in the red, while some fit better in the blue spectral region. To validate this index‐matching property found in the material level, we prepared some polymer‐dispersed liquid‐crystal devices. Good correlations between material and device performances are obtained. 相似文献
146.
Greg Keane 《建设机械技术与管理》2008,(6)
澳大利亚墨尔本海边城市开发区的南星观象摩天轮高120m.建筑技术相当先进,2008年下半年完工后,将是南半球最大的摩天轮。 相似文献
147.
Oldham Greg R.; Cummings Anne; Mischel Leann J.; Schmidtke James M.; Zhou Jing 《Canadian Metallurgical Quarterly》1995,80(5):547
Using a quasi-experimental design, this study examined relations between stereo headset use and employee work responses. Employees (N?=?256) worked on 32 jobs in an office of a retail organization. Employees indicated whether they were interested in using stereos at work. From those expressing an interest, a random sample (n?=?75) was assigned to a stereo condition. These employees used headsets at work for 4 weeks. The remaining employees (n?=?181) were assigned to a control condition and were not allowed to use stereos. Results indicated that employees in the stereo condition exhibited significant improvements in performance, turnover intentions, organization satisfaction, mood states, and other responses. The mood state of relaxation best explained the relation between stereo use and performance. Finally, employees in relatively simple jobs responded most positively to the stereos. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
148.
Steven L. Richheimer Matthew W. Bernart Greg A. King Michael C. Kent David T. Beiley 《Journal of the American Oil Chemists' Society》1996,73(4):507-514
A high-performance liquid chromatography method for analyzing the phenolic diterpenes present in rosemary (Rosmarinus officinalis L.) and commercial rosemary extracts is reported. Carnosic acid was the major phenolic diterpene present in rosemary leaves,
with lesser amounts of 12-methoxycarnosic acid and carnosol. Several commercial rosemary extracts also were analyzed by this
method, and in addition to these three compounds other phenolic diterpenes, such as 7-methoxyrosmanol, 7-methoxy-epirosmanol,
and rosmanol, were found in some samples. These latter three compounds seem to be artifacts, produced from carnosic acid by
oxidation and cyclization. The major phenolic diterpenes were isolated, and their relative antioxidatn activities in soybean
oil were measured by the Rancimat. The potency of carnosic acid was more than twice that of any other compound. The antioxidant
activity of pure carnosic acid was compared to butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), and tertiary
butylhydroquinone (TBHQ) and was several times greater than BHT and BHA but less than TBHQ. Nuclear magnetic resonance data
for several of the compounds that were incompletely characterized in previous literature are reported. 相似文献
149.
150.
This paper compares the modification mechanism provided by ethylene‐octene (EO) copolymer to that of ethylene‐propylene‐diene terpolymer (EPDM) rubber. Within the limits of this study, the highest impact strength was achieved at 30–40% rubber content, regardless of the rubber type. An increase in rubber melt viscosity resulted in overall greater impact strength. At the optimum concentration, the high‐viscosity (MFI = 1 to 5) EO rubber provided modification mainly via a crazing mechanism, while the EPDM rubber functioned by energy dissipation through the three‐dimensional network structure formed with the polypropylene matrix. This paper also discusses the effects of the processing conditions on the physical properties of PP/EPR copolymer. An increase in processing temperature and screw speed resulted in a reduced number of discrete rubber particles and nearly no or very slight increase in impact strength, but a very significant reduction in tensile strength and tensile modulus. 相似文献