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Psyllids Testing Form
Get PDFRequest form for psyllids going to Texas High Plains Plant Disease Diagnostic La
Structural Templation in Metal���Organic Framework���Derived Carbons
No full textAs their cost has decreased, metal���organic frameworks (MOFs) have become attractive templates for the development of new functional materials such as MOF-derived carbons (MOFdCs). MOFdCs, which are comprised of porous carbon derived from the MOF linkers and nanoparticulate metal species derived from the inorganic components of the MOF, hold great promise in applications ranging from hydrogen storage to electrocatalysis. Despite this promise, MOFdCs are limited by the black-box nature of their synthesis and the inherent challenges of designing and characterizing poorly ordered materials. In this work, I have investigated the templating effects of MOF structure and composition in a systematic way to advance our ability to design and synthesize MOFdCs with specific features. Firstly, I investigated the templating effect of the inorganic building unit of the MOF on the structure of the inorganic nanoparticles by carbonizing three different zirconium MOFs. I found that calcination of a MOF containing extended Zr-oxo chains produced zirconia nanoparticles that were significantly more well-ordered than calcination of MOFs with discrete Zr6-oxo clusters. Secondly, I exploited the known decomposition mechanisms of the iron MOF PCN-250 to target specific properties in the material. I developed a two-step calcination procedure to synthesize a MOFdC exhibiting high porosity and only containing iron(II,III) oxide as the inorganic component, features which had not previously been achieved simultaneously in a PCN-250-derived carbon. Furthermore, I demonstrated the generalizability of this procedure to mixed-metal PCN-250-Fe2M (M = Mn, Co) to form Fe2MO4 nanoparticles. Finally, I used two zirconium MOFs, PCN-222-M and UiO-67-bpy-M (M = Co, Ni, Cu, Zn) to systematically investigate the influence of secondary metals on the structure of zirconia nanoparticles and the effect of template MOF structure on the evolution of distinct secondary metal species. While the effect of the secondary metals on the zirconia structure was minimal, the phase and oxidation state of the secondary metal species varied based on the template MOF. By using a suite of in situ and ex situ techniques to probe the local and average structures of the materials, I was able to describe differences in the structure of the final materials and the evolution of gaseous species from the MOFs as they were carbonized. Together, these projects provide a window into the black box of MOFdC synthesis and give insight into MOF features that can be used to control the structure of MOF-derived materials
Do Liver Abscesses in Beef x Dairy Cattle Influence Postmortem Metabolites and Lean Color?
No full textBeef x Dairy (BxD) steers (n = 537) were identified and a subset (n = 201) were evaluated for the presence and severity of liver abscesses. Carcasses were selected (n = 30) to determine the relationship between liver abscesses, metabolites, and lean color. Three abscess categories were identified, 1) MAJOR (A+), 2) MINOR (A-,A), and 3) NORMAL (0). Liver, and pre-rigor M. sternomandibularis (Pre-Sterno) tissues were collected. Carcass data were recorded, post-rigor M. sternomandibularis (Post-Sterno) excised, and instrumental color and pH measured. Beef strip loins were collected (n = 30); one steak was frozen for further analyses and two steaks from each loin were evaluated for instrumental color over 5 d. Liver, Pre-Sterno, Post-Sterno, and strip loin tissue were evaluated for Glucose-6-Phosphate (G-6-P), glucose, glycogen, lactate, and citrate concentration. Liver abscess rate was 43.78% (n = 201), with 29.36% severe. There was no (P = 0.4374) difference in pH, and NORMAL possessed the highest in-plant a* values (P = 0.0211). For instrumental color over 5 d, MINOR had the highest L* values (P = 0.0035), MAJOR the highest a* (P = 0.0020) and chroma values (P < 0.0001), MAJOR and MINOR the highest b* values (P < 0.0001), and NORMAL the highest hue values (P < 0.0001). MAJOR had the highest ratio of oxymyoglobin (P < 0.0001) and deoxymyoglobin (P = 0.0088), and NORMAL the highest metmyoglobin (P < 0.0001). NORMAL had the most liver G-6-P (P = 0.0012), least liver glycogen (P = 0.342), most Pre-Sterno glucose (P = 0.0020), and most strip loin G-6-P (P = 0.0026). MAJOR contained the most liver glucose (P = 0.0054), and strip loin citrate (P = 0.0436). MAJOR and MINOR had the most liver glycogen (P = 0.0342), leading to the highest liver glycolytic potential (P = 0.0245). Initial a* values revealed a redder color for NORMAL early postmortem, but metabolite differences influenced higher color stability for MAJOR and MINOR over 5 d. Overall, differences in color and color stability of strip loins indicate that there could be a relationship between liver abscesses and postmortem lean color
Laser Heating and Ignition of HTPB-Based Solid Fuels in an Oxidizing Environment
No full textA solid fuel ramjets (SFRJ) is an air-breathing propulsion system which touts superior energy density (i.e., specific impulse) in comparison to analogous solid propellant systems and are competitive for long-range or high-speed applications. In the current study, a constant-volume strand burner was used to simulate SFRJ ignition and combustion conditions. Laser heating and ignition experiments were conducted with a representative SFRJ fuel (hydroxyl-terminated polybutadiene, HTPB) in dry air at three different pressure ranges (45 �� 5, 85 �� 5, and 130 �� 5 psia) over a range of laser power fluxes (55-755 W/cm^2). Ignition delay time data were measured by four methods via a light emission diagnostic or high-speed video data. Two separate ignition delay time trends in the low- (< 110 W/cm^2) and high-power regimes were observed for HTPB in air at the pressure condition evaluated here. The disparate trends were attributed to heat transfer effects occurring over larger timescales in the low-power regime. In addition, fundamental insight into the steady-state, laser-driven combustion of HTPB in air was deduced from high-speed video analysis.
AP smaller than 90 ��m are not commercially available. To incorporate AP smaller than 90 ��m on the lab-scale, an in-house fine AP manufacturing process was devised. Using a LabRAM acoustic mixer, AP was decreased from an average particle size of 90 microns to ~2 microns. Thorough particle size characterization was completed via scanning electron microscopy (SEM) and composite propellant ballistic experiments.
Additional formulations with 5 wt% AP and Al were investigated for IDT at one pressure condition (45 �� 5 psia). Two separate ignition delay time trends in the low- (< 110 W/cm^2) and high-power regimes were observed for these formulations as well. Significant IDT differences were not observed relative to the HTPB baseline, although the ignition mechanisms introduced by the addition of AP and Al did have an impact on the ignition characteristics. A series of HSV snapshots at relevant conditions to show the different mechanisms are discussed.
Multiple methods to accurately measure HTPB regression rates were also investigated. An initial data set of the relationship between regression and power flux was produced
Three Miles Out And Beyond
No full textpgs. 49-54This article discusses the history of the federal government and coastal states' efforts with management of our nation's continental shelf resources.http://gbic.tamug.edu/request.ht
The Effect of Different Nozzles on the Mechanical Properties of 3D Printed Concrete
Get PDFThis study aims at investigating the influence of different nozzle geometries on the mechanical properties of 3D printed concrete. The three nozzle geometries that will be studied are the standard circular nozzle acting as the control, a rectangular straight nozzle, and a 90 degrees bent rectangular nozzle. For this experiment a ready-to-mix concrete acquired form DCP will be utilized to ensure consistency and focus solely on the effects of nozzle geometries. Compressive, flexural, and interlayer bond strengths are the mechanical properties being assessed on the printed samples from each nozzle geometry. The results of this study showed a significant enhancement in the mechanical properties of samples printed with the straight rectangular nozzle (SRN). The 28 day interlayer bond strength test achieved the highest value of 2.02 MPa for the SRN showing improvements in the layer adhesion of the printed structure, indicating a robust bond between layers which is crucial for structural integrity. Similarly, the 28 day flexural test results showed superior advancements with a value of 6.19 MPa for the SRN geometry, providing an optimized geometry for resisting bending forces. Overall, the SRN recorded the highest percentage increase when compared to CN. However, issues were encountered with the ARN because of its fixed orientation, which negatively impacted its percentage increase results. The study confirms that nozzle geometry has a fundamental effect on the mechanical properties of 3D printed concrete. Thus, it is of utmost importance to optimize these geometries which would lead to desired improvements in the realm of concrete 3D printing. This research provides the basis for the advancement of 3D printing methods, offering a route to more resilient and successful construction techniques