Thesis (M.S. in civil engineering)--Washington State University, December 2008. / Title from PDF title page (viewed on Mar. 2, 2009). "Department of Civil and Environmental Engineering." Includes bibliographical references.

The intersection of decreasing resource size and increasing population and its associated demand creates a pressing need to develop products that act as alternatives to solid sawn lumber. Engineered composite lumber is one such alternative. The product described herein utilizes a modified form of sawn lumber as the raw material. The objective of this research was to manufacture, mechanically test, and evaluate a novel type of engineered lumber. Non destructive evaluation of raw materials and finished beams, and final mechanical testing to determine mean strength and stiffness values as per ASTM 5456 were used. The mechanical property data was converted into design values for fiber stress in bending (Fb) and stiffness (MOE). These design values was compared to those published by the U.S. (NDS) for wood construction. Pine logs were reduced into cants and further processed into matched symmetrical trapezoids. Symmetrical trapezoids were then non-destructively evaluated via E-computer and Director, and sorted by results. Next, the sorted trapezoids were matched into pairs and assembled into bowtie beams. Polyvinyl acetate adhesive was used throughout. Stiffness of the manufactured beams was nondestructively evaluated too. Then the beams were mechanically tested. The information from the E-computer was correlated to the strength and stiffness for each beam. The design strength and stiffness was compared to the values of sections of equivalent depth and maximum width as shown in the NDS. Also, non destructive test values were compared and correlated to those from the destructive tests. Finally, the design strength and stiffness values were respectively multiplied by the sectional area or the moment of inertia. This produced a strength efficiency factor and a stiffness efficiency factor. These factors were compared to factors derived from multiplying the design strength or design stiffness values (from the NDS) times the area or the moment of inertia of a rectangular section of equivalent depth and maximum width. It is found that the mechanically efficient bowtie section produced an increased strength and stiffness efficiency as compared to that of solid sawn material.

Myocardial infarction is one of the most severe acute pathologies of the cardiovascular system. The adult mammalian heart is indeed unable to regenerate most of the lost cardiomyocytes (CMs) after cardiac injury. The loss of cardiomyocytes and the myocardial scarring after myocardial infarction eventually compromise contractility of the remaining myocardium, leading to heart failure. Therefore, promoting heart regeneration is one of the most crucial therapeutic targets in cardiovascular medicine. The lack of regenerative response is due to the loss of proliferative capacity of adult CMs which in mice occurs seven days after birth. One of the events which occur at birth in neonatal hearts is a sudden increase in mechanical loading that may contribute to switching mammal CMs phenotype from neonatal proliferative to adult postmitotic. Therefore, understanding the role of mechanotransduction in regulating the balance between CM proliferation and maturation may bring us to the identification of unknown mediators and new potential strategies to induce cardiac regeneration. Regulation of mechanical load in bi-dimensional cultures of CMs can be achieved in different ways, however, the poor degree of CM maturation that can be reached in a culture dish together with the lack of a tridimensional structure represent a major limitation to performing mechanotransduction studies. In our work we developed a novel system to study mechanotransduction of CMs based on 3D culture of cardiac cells, called engineered heart tissues (EHTs), that allow us to reduce or increase mechanical loading easily. We show that the three-dimensional setting of the culture leads to an improvement of CM maturation that may be reversed by mechanical unloading inducing cell proliferation. On the other hand, a persisting overload stimulus eventually induces CM switch to a more mature phenotype with a low degree of proliferation. Also, we have focused our work on developing an EHT-based model able to recapitulate the adult infarct injury in order to investigate the biology of cardiac regeneration in this setting. Specifically, we set up a cryoinjury protocol that is relatively easy and reproducible. Cryoinjury produces a localized injury without compromising EHT’s structural integrity. Indeed, all the EHTs subjected to cryoinjury preserved their contractile activity and did not show any significant change in shape. Considering that EHTs are unpurified cardiac culture rich in fibroblast and endothelial cells, we observed that cryoinjury induce fibroblast proliferation and activation together with a lack of proliferative response of the cardiomyocytes which is, on the other hand, present in the early phase of EHT’s development, similarly to what has been shown in mice and rats after myocardial infarction, highlighting the robustness of our cryoinjury approach as a model to investigate cardiac regeneration.

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Thesis (M.S. in materials science and engineering)--Washington State University, December 2007. / Includes bibliographical references.

Thesis (M.S. in materials science and engineering)--Washington State University, May 2007. / Includes bibliographical references.

This thesis discusses the field testing of a newly-developed product, a geosynthetic capillary break (GCB). The GCB was developed for use in engineered soil covers when a cover incorporating a capillary break effect would be desirable, but the coarse-grained material (gravel or sand) is unavailable or uneconomical. Engineered soil covers aim to reduce the amount of acid generated from sulphide bearing waste by limiting the ingress of water and/or oxygen. The GCB is a geosynthetic system that is composed of a finely ground rock flour sandwiched between two nonwoven geotextiles and manufactured as a composite layer by needle punching in a process similar to the used for GCL (geosynthetic clay liner). The goal of the GCB is to recreate the capillary break that is achieved with soil layers using a geosynthetic product that is only a few centimetres thick and that can be rolled up and for transportation, The GCB concept has been demonstrated in a previous study (Park, 2005) based on laboratory column studies and computer modelling. The goal of this project was to determine the effectiveness of the GCB when applied at field scale. Four 25 square test plots were constructed at the tailings management area (TMA) of the HudBay Minerals Inc.(HudBay) mine site located near Flin Flon, MB. One plot contained 1 m of cover soil over top of the GCB (Plot A), one contained only 1 m of cover soil (Plot B), one contained 0.3 m of cover soil over top the GCB (Plot C), and one consisted of a conventional capillary break system with 1 m of cover soil over lying 0.2 m of sand. All of the plots, along with a control plot with no cover, were instrumented with water content sensors and gas sampling ports to monitor the movement of water and oxygen through the various covers. Matric suction sensors were also installed in Plots A and B to measure the water suction within the covers. A meteorological station was installed to gather climatic data which was used to develop a water balance for each of the plots. The plots were constructed and instrumented in the fall of 2005. Data was collected and analyzed until spring of 2007. Data from the water content sensors show that the GCB was effective in increasing the water content in the soil portion of the cover system. The suction sensors show that the suction across the GCB drops significantly (40 kPa versus less than 1 kPa) as compared to plots which contain no GCB. Data from the gas concentration sensors show that the plots containing capillary breaks reduce the oxygen flux into the tailings. The plots containing the GCB (Plots A and C) resulted in the lowest flux rates, followed by the sand capillary break (Plot D )and no capillary break (Plot B), respectively. This reduction in oxygen flux will reduce the amount of acid generated from waste, as oxygen is required for the creation of acid mine drainage. Overall the study demonstrated that at field scale that the GCB is effective in limiting the ingress of water and oxygen into the tailings under the observed conditions and the manufactured GCB is comparable to the performance of the previous hand constructed column tests.