436 research outputs found
An assessment of myotube morphology, matrix deformation and myogenic mRNA expression in custom-built and commercially available engineered muscle chamber configurations
There are several three-dimensional (3D) skeletal muscle (SkM) tissue engineered
models reported in the literature. 3D SkM tissue engineering (TE) aims to recapitulate
the structure and function of native (in vivo) tissue, within an in vitro environment.
This requires the differentiation of myoblasts into aligned multinucleated myotubes
surrounded by a biologically representative extracellular matrix (ECM). In the present
work, a new commercially available 3D SkM TE culture chamber manufactured
from polyether ether ketone (PEEK) that facilitates suitable development of these
myotubes is presented. To assess the outcomes of the myotubes within these
constructs, morphological, gene expression, and ECM remodeling parameters were
compared against a previously published custom-built model. No significant differences
were observed in the morphological and gene expression measures between the
newly introduced and the established construct configuration, suggesting biological
reproducibility irrespective of manufacturing process. However, TE SkM fabricated
using the commercially available PEEK chambers displayed reduced variability in both
construct attachment and matrix deformation, likely due to increased reproducibility
within the manufacturing process. The mechanical differences between systems may
also have contributed to such differences, however, investigation of these variables
was beyond the scope of the investigation. Though more expensive than the custombuilt
models, these PEEK chambers are also suitable for multiple use after autoclaving.
As such this would support its use over the previously published handmade culture
chamber system, particularly when seeking to develop higher-throughput systems or
when experimental cost is not a factor
Whither the Nixon Board?
The Nixon administration has now appointed a majority of members to the National Labor Relations Board. With this change in Board composition have come significant shifts in labor policy. The authors of this Article examine these shifts in policy in light of the approaches of past Boards
Improving the consultant approval process
This paper will explore the qualification processes used to evaluate consultants
for SCDOT projects. The processes will be flowcharted and analyzed. Data from other
state DOTs, consultants and the internet will be gathered and evaluated. Based on the
information collected and analyzed, recommendations for improvement will be discussed as well as an implementation plan provided. A method of evaluation will also be developed and discussed. Finally, the key findings and recommendations will be summarized
Development of Inflatable Entry Systems Technologies
Achieving the objectives of NASA s Vision for Space Exploration will require the development of new technologies, which will in turn require higher fidelity modeling and analysis techniques, and innovative testing capabilities. Development of entry systems technologies can be especially difficult due to the lack of facilities and resources available to test these new technologies in mission relevant environments. This paper discusses the technology development process to bring inflatable aeroshell technology from Technology Readiness Level 2 (TRL-2) to TRL-7. This paper focuses mainly on two projects: Inflatable Reentry Vehicle Experiment (IRVE), and Inflatable Aeroshell and Thermal Protection System Development (IATD). The objectives of IRVE are to conduct an inflatable aeroshell flight test that demonstrates exoatmospheric deployment and inflation, reentry survivability and stability, and predictable drag performance. IATD will continue the development of the technology by conducting exploration specific trade studies and feeding forward those results into three more flight tests. Through an examination of these projects, and other potential projects, this paper discusses some of the risks, issues, and unexpected benefits associated with the development of inflatable entry systems technology
Supersonic Retropropulsion Experimental Results from the NASA Langley Unitary Plan Wind Tunnel
A new supersonic retropropulsion experimental effort, intended to provide code validation data, was recently completed in the Langley Research Center Unitary Plan Wind Tunnel Test Section 2 over the Mach number range from 2.4 to 4.6. The experimental model was designed using insights gained from pre-test computations, which were instrumental for sizing and refining the model to minimize tunnel wall interference and internal flow separation concerns. A 5-in diameter 70-deg sphere-cone forebody with a roughly 10-in long cylindrical aftbody was the baseline configuration selected for this study. The forebody was designed to accommodate up to four 4:1 area ratio supersonic nozzles. Primary measurements for this model were a large number of surface pressures on the forebody and aftbody. Supplemental data included high-speed Schlieren video and internal pressures and temperatures. The run matrix was developed to allow for the quantification of various sources of experimental uncertainty, such as random errors due to run-to-run variations and bias errors due to flow field or model misalignments. Preliminary results and observations from the test are presented, while detailed data and uncertainty analyses are ongoing
- …