Missouri River Studies: Alluvial Morphology and Engineering Soil Classification, HR-1, Progress Report, 1960

The primary purposes of this investigation are: 1) To delineate flood plain deposits with different geologic and engineering properties. 2) To provide basic data necessary for any attempt at stabilizing flood plain deposits. The alluvial valley of the Missouri River adjacent to Iowa was chosen as the logical place to begin this study. The river forms the western boundary of the state for an airline distance of approximately 139 miles; and the flood plain varies from a maximum width of approximately 18 miles (Plates 2 and 3, Sheets 75 and 75L) to approximately 4 miles near Crescent, Iowa (Plate 8, Sheet 66). The area studied includes parts of Woodbury, Monona, Harrison, Pottawattamie, Mills, and Fremont counties in Iowa and parts of Dakota, Thurston, Burt, Washington, Douglas, Sarpy, Cass and Otoe counties in Nebraska. Plate l is an index map of the area under consideration.

Field Evaluation of Engineering Fabrics for Asphalt Concrete Resurfacing - Audubon County, HR-360, Final Report, 2001

An ACC overlay is most often the rehabilitative effort used to maintain the serviceability of either an ACC or PCC pavement. The major problem in durability of this ACC overlay comes from reflective cracking. These cracks usually open, allowing water to enter the unsealed crack and strip the ACC in the overlay. The stripping of the ACC allows accelerated deterioration at the crack. Two engineering fabrics were evaluated in this project in order to determine their effectiveness in reducing reflective cracking. These two materials are: • PavePrep, Contech Construction Products Inc. • ProGuard, Phillips Fiber Corporation The data indicated a statistically significant decrease in reflective crack formation in the ProGuard fabric sections compared to control. There was little evidence of a similar effect from the PavePrep fabric sections compared to control. However, the rate of cracking (the rate of formation of new cracks) for both fabrics and control tended to be similar after three years. The benefits of using these fabrics (possible delay of some crack formation by two years) on this project did not outweigh the costs of up to $4200.00 per mile.

Human fetal bone cells in delivery systems for bone engineering.

The aim of this study was to culture human fetal bone cells (dedicated cell banks of fetal bone derived from 14 week gestation femurs) within both hyaluronic acid gel and collagen foam, to compare the biocompatibility of both matrices as potential delivery systems for bone engineering and particularly for oral application. Fetal bone cell banks were prepared from one organ donation and cells were cultured for up to 4 weeks within hyaluronic acid (Mesolis(®)) and collagen foams (TissueFleece(®)). Cell survival and differentiation were assessed by cell proliferation assays and histology of frozen sections stained with Giemsa, von Kossa and ALP at 1, 2 and 4 weeks of culture. Within both materials, fetal bone cells could proliferate in three-dimensional structure at ∼70% capacity compared to monolayer culture. In addition, these cells were positive for ALP and von Kossa staining, indicating cellular differentiation and matrix production. Collagen foam provides a better structure for fetal bone cell delivery if cavity filling is necessary and hydrogels would permit an injectable technique for difficult to treat areas. In all, there was high biocompatibility, cellular differentiation and matrix deposition seen in both matrices by fetal bone cells, allowing for easy cell delivery for bone stimulation in vivo. Copyright © 2011 John Wiley & Sons, Ltd.

Quantitative comparison between simulations of seismic wave propagation in heterogeneous poro-elastic media and equivalent visco-elastic solids for marine-type environments

There is increasing evidence to suggest that the presence of mesoscopic heterogeneities constitutes an important seismic attenuation mechanism in porous rocks. As a consequence, centimetre-scale perturbations of the rock physical properties should be taken into account for seismic modelling whenever detailed and accurate responses of specific target structures are desired, which is, however, computationally prohibitive. A convenient way to circumvent this problem is to use an upscaling procedure to replace each of the heterogeneous porous media composing the geological model by corresponding equivalent visco-elastic solids and to solve the visco-elastic equations of motion for the inferred equivalent model. While the overall qualitative validity of this procedure is well established, there are as of yet no quantitative analyses regarding the equivalence of the seismograms resulting from the original poro-elastic and the corresponding upscaled visco-elastic models. To address this issue, we compare poro-elastic and visco-elastic solutions for a range of marine-type models of increasing complexity. We found that despite the identical dispersion and attenuation behaviour of the heterogeneous poro-elastic and the equivalent visco-elastic media, the seismograms may differ substantially due to diverging boundary conditions, where there exist additional options for the poro-elastic case. In particular, we observe that at the fluid/porous-solid interface, the poro- and visco-elastic seismograms agree for closed-pore boundary conditions, but differ significantly for open-pore boundary conditions. This is an important result which has potentially far-reaching implications for wave-equation-based algorithms in exploration geophysics involving fluid/porous-solid interfaces, such as, for example, wavefield decomposition.

Fly Ash Soil Stabilization for Non-Uniform Subgrade Soils, Volume I: Engineering Properties and Construction Guidelines, TR-461, 2005

Soil treated with self-cementing fly ash is increasingly being used in Iowa to stabilize fine-grained pavement subgrades, but without a complete understanding of the short- and long-term behavior. To develop a broader understanding of fly ash engineering properties, mixtures of five different soil types, ranging from ML to CH, and several different fly ash sources (including hydrated and conditioned fly ashes) were evaluated. Results show that soil compaction characteristics, compressive strength, wet/dry durability, freeze/thaw durability, hydration characteristics, rate of strength gain, and plasticity characteristics are all affected by the addition of fly ash. Specifically, Iowa selfcementing fly ashes are effective at stabilizing fine-grained Iowa soils for earthwork and paving operations; fly ash increases compacted dry density and reduces the optimum moisture content; strength gain in soil-fly ash mixtures depends on cure time and temperature, compaction energy, and compaction delay; sulfur contents can form expansive minerals in soil–fly ash mixtures, which severely reduces the long-term strength and durability; fly ash increases the California bearing ratio of fine-grained soil–fly ash effectively dries wet soils and provides an initial rapid strength gain; fly ash decreases swell potential of expansive soils; soil-fly ash mixtures cured below freezing temperatures and then soaked in water are highly susceptible to slaking and strength loss; soil stabilized with fly ash exhibits increased freeze-thaw durability; soil strength can be increased with the addition of hydrated fly ash and conditioned fly ash, but at higher rates and not as effectively as self-cementing fly ash. Based on the results of this study, three proposed specifications were developed for the use of self-cementing fly ash, hydrated fly ash, and conditioned fly ash. The specifications describe laboratory evaluation, field placement, moisture conditioning, compaction, quality control testing procedures, and basis of payment.

Covalent cell surface functionalization of human fetal osteoblasts for tissue engineering.

The chemical functionalization of cell-surface proteins of human primary fetal bone cells with hydrophilic bioorthogonal intermediates was investigated. Toward this goal, chemical pathways were developed for click reaction-mediated coupling of alkyne derivatives with cellular azido-expressing proteins. The incorporation via a tetraethylene glycol linker of a dipeptide and a reporter biotin allowed the proof of concept for the introduction of cell-specific peptide ligands and to follow the reaction in living cells. Tuning the conditions of the click reaction resulted in chemical functionalization of living human fetal osteoblasts with excellent cell survival.

Re-Engineering CTE in Iowa: Aligning Career and Technical Education Reform, Workforce Development and Economic Development, August 2007

Iowa is a relatively small state and is on the rebound economically. It has an overall population that is stable, but which is shifting within the state from more rural areas to suburban and urban centers. There is a very tight labor market with high levels of employment. Iowa now has a time-sensitive opportunity to exert global leadership in renewable energy, while maintaining its leadership in other key industries like finance and agriculture.

Constraints on Miocene oceanography and climate in the Western and Central Paratethys: O-, Sr-, and Nd-isotope compositions of marine fish and mammal remains

The Paratethys evolved as a marginal sea during the Alpine-Himalayan orogeny in the Oligo-Miocene. Sediments from the northern Alpine Molasse Basin, the Vienna, and the Pannonian Basins located in the western and central part of the Paratethys thus provide unique information on regional changes in climate and oceanography during a period of active Alpine uplift Oxygen isotope compositions of well-preserved phosphatic fossils recovered from the sediments support deposition under sub-tropical to warm-temperate climate with water temperatures of 14 to 28 degrees C for the Miocene. delta(18)O values of fossil shark teeth are similar to those reported for other Miocene marine sections and, using the best available estimates of their biostratigraphic age, show a variation until the end of the Badenian similar to that reported for composite global record. The (87)Sr/(86)Sr isotope ratios of the fossils follow the global Miocene seawater trend, albeit with a much larger scatter. The deviations of (87)Sr/(86)Sr in the samples from the well-constrained seawater curve are interpreted as due to local input of terrestrially-derived Sr. Contribution of local sources is also reflected in the epsilon(Nd) values, consistent with input from ancient crystalline rocks (e.g., Bohemian Massif and/or Mesozoic sediments with epsilon(Nd) < -9. On the other hand, there is evidence for input from areas with Neogene volcanism as suggested by samples with elevated epsilon(Nd) values >-7. Excluding samples showing local influence on the water column, an average epsilon(Nd) value of -7.9 +/- 0.5 may be inferred for the Miocene Paratethys. This value is indistinguishable from the epsilon(Nd) value of the contemporaneous Indian Ocean, supporting a dominant role of this ocean in the Western and Central Paratethys. (C) 2008 Elsevier B.V. All rights reserved.