136879 research outputs found
Sort by
The Reconstruction of Riesman's Social Character Social Types: Loss of Indigenous Cultural Identity
No full textThe Navajo tribe is one of the largest Indigenous tribes in the United States. With the continuous issues that the Navajo population faces, the loss of cultural identity is a primary concern. Applying David Riesman's theory of social characters, the three recontextualizations: tradition-directed, inner-directed, and other-directed, have yet to be done. Applying and recontextualizing David Riesman's theory will continue to identify and explore Indigenous cultural identity. David Riesman writes mainly about white American suburban society (other-directed) and applies his neglected concepts on traditional directedness. Applying ancestral traditions through the recontextualization of tradition-directed and inner-directed can cause the loss of connection between the Navajo tribe, cultural roots, and cultural identity. Applying Riesman theory to Indigenous tribes will reflect that the difference between the white population (other-directedness) and the Indigenous tribes (traditional-directedness) continues to fit even today. It will return to full circle and follow Riesman's concepts to a certain extent. The other recontextualization is the struggle between each type of social character's three social traits and the direction of modernization
A Study of Hard and Soft Materials Subjected to Ballistic and Hypervelocity Impact
No full textHypervelocity impacts (HVIs) (���2.0 km/s) can induce extremely high strain rates (>10��� s�����). Hence, developing materials to withstand HVIs is a key challenge in the effort to enhance protective infrastructure. Furthermore, computational software such as the Elastic Plastic Impact Computation (EPIC) code, can accelerate the development of these material systems.
Thermoplastics such as high-density polyethylene (HDPE) can be used to offer HVI damage resistance without compromising on weight and cost. This document reports a modeling effort to predict the HVI response of 6.35 mm HDPE plates when impacted by 10 mm Al spheres travelling 2.0���6.8 km/s. It was found that the simulation accurately predicted debris cloud velocity and shape, hole size, and mass loss for impact velocities <5.5 km/s.
Often, much denser high-performance concrete (HPC) mixtures like BBR9 are used as a HVI resistant building material. This work reports simulation and experimental efforts to predict the HVI response of BBR9 plates of varying thickness (25.4���127.0 mm) impacted by 10 mm S2 tool steel spheres travelling 1.8���3.1 km/s. Simulations reflected experimental fragmentation and energy absorption results well, and it was found that they even captured the transition region in which an increase in impact velocity resulted in a decrease in debris cloud velocity.
Layering materials to exploit their strengths can result in composites with increased kinetic energy dissipation and reduced target weight. The results reported in the HDPE and BBR9 investigations lead to their use in composite "sandwich" targets that can be optimized for key metrics. To test this principle, a multifaceted computational and experimental approach was used. By adjusting the volume fractions of the two materials in EPIC and subjecting the layered targets to a 2.0 km/s impact from a 10 mm S2 tool steel projectile, a mass-optimized, 50.8 mm thick composite target that dissipated maximum projectile kinetic energy was generated. Subsequently, the target was subjected to V������ ballistic limit testing with a 12.7 mm S2 tool steel spherical projectile, where it was found that the simulation-predicted and actual ballistic limits were within <1% of one another, justifying the idea that simulation-informed optimization is a useful tool in material design
An Evaluation of Alternatives for Updating Base Acres in the 2024 Farm Bill
No full textGiven that the income-support provisions in the farm bill have been decoupled from production for more than two decades, base acres are no longer reflective of planted acres in the United States. Three alternatives are currently being discussed to better align base acres with current plantings in the next farm bill: 1) a reallocation of bases to current plantings, 2) a forced update to current plantings, and 3) a rolling average of the plantings from the previous two years. There undoubtedly will be winners and losers across individual operations, crops, and regions. Knowing who will be impacted would enable Congress to make more informed decisions regarding base updates. To comprehensively evaluate the alternatives, this study undertook a farm-level and national analysis.
The farm-level analysis was implemented by collecting data from four representative farms maintained by the Agricultural and Food Policy Center at Texas A&M University. For each farm, base acres were calculated for the three alternatives, and stochastic simulation was used to determine a five-year forecast of average government payments, ending cash, and ending real net worth. The national analysis was conducted by collecting public data from the Department of Agriculture���s Farm Service Agency for nine covered commodities and calculating new base acres per county to determine absolute gains and losses. The absolute change per crop per county was totaled to determine the deviations between the current baseline and each scenario being analyzed.
The results from the farm-level and national analysis indicate a wide variety of impacts on individual farms, crops, and regions. While maintaining current base acres might be the optimal solution for one location or commodity, it is apparent that the same scenario would be less preferred by others. One universal option (e.g., to reallocate base acres) might not be the best solution; in fact, allowing producers to choose amongst several options might be the best route for baseline modification in the next farm bill, recognizing that approach will also cost the most
Characterization of Soil Physical and Hydraulic Properties of TexMesonet Monitoring Sites
No full textOperated by the Texas Water Development Board, the TexMesonet comprises 100 monitoring stations across Texas. These stations record 11 environmental variables, which include soil moisture measurements at depths of 5, 10, 20, and 50 cm. While soil moisture data from other networks have been utilized to enhance crop yield estimation, develop drought indices, estimate potential groundwater recharge, and validate remote sensing soil moisture data, TexMesonet soil moisture data remain underutilized for such applications. This underutilization is due to the absence of comprehensive, site- and depth-specific data on soil physical and hydraulic properties. The objectives of this project are twofold: firstly, to characterize the soil physical and hydraulic properties at TexMesonet sites, and secondly, to estimate site- and depth-specific soil hydraulic parameters using the Rosetta3 pedotransfer function. This was achieved through extensive field sampling and laboratory measurements at 30 stations, including determining sand, silt, and clay percentages, bulk density, and volumetric water content at field capacity (-33 kPa) and permanent wilting point (-1500 kPa). These measurements were then applied in the Rosetta3 pedotransfer function to derive site-and depth-specific soil hydraulic parameters. The resulting database includes ten soil physical and hydraulic properties for each site and depth, leading to 218 data points across the 30 study sites. Within the TexMesonet, ten of the twelve USDA soil textural classes were identified, with silt and sand not represented. The mean absolute error (MAE) between the measured and predicted water retention curves ranged from 0.025 cm�� cm- �� to 0.13 cm�� cm- ��. Additionally, the MAE for volumetric water content estimates from TexMesonet sensors versus direct sampling was 0.081 cm�� cm- ��. With further sampling and expansion to all TexMesonet sites, this database has strong potential to provide critical information for improving water resource management applications in Texas, including irrigation scheduling and predicting floods and droughts
Enhancing the Nutritional Quality of Red Leaf Lettuce by Optimizing End-of-Production Supplemental LED Lighting
No full textRed leaf lettuces (Lactuca sativa) are commercially significant leafy vegetables grown both in open fields and controlled-environment facilities such as greenhouses and indoor farms. These plants produce anthocyanins, a group of secondary metabolites that enhance their red coloration and nutritional value. However, low light levels in controlled environments can reduce the biosynthesis of anthocyanins and other key phytochemicals such as phenolics, ascorbic acid, and carotenoids. The light conditions in controlled environments could be optimized by leveraging the light-emitting diodes (LED) technology, potentially improving phytochemical accumulation. This research had two primary objectives: 1) to assess whether a higher intensity, shorter duration blue light would increase anthocyanin production more than a lower intensity, longer duration blue light, given the same total cumulative amount of supplemental blue light applied at the end of production (EOP), and 2) to compare the effectiveness of different light spectra, including red, blue, violet, ultraviolet-A (UVA), and ultraviolet-B (UVB), on enhancing anthocyanins and total phenolics in red lettuce during EOP. Our results indicated that a medium intensity of blue light applied over a medium duration resulted in the highest anthocyanin levels when the same amount of supplemental blue light was applied at varying intensities and durations. In evaluating various monochromatic light treatments, we found that supplemental violet light resulted in the highest leaf expansion and biomass, while UVB radiation (3 ��mol m^- �� s^-1 ), despite its lower intensity compared to other light spectra (60 ��mol m^- �� s^-1 ), was most effective at enhancing the accumulation of phytonutrients such as anthocyanins and phenolics but caused yield reductions. We caution that the tradeoff between enhanced crop nutritional quality and reduced crop yield must be carefully considered in commercial applications
Effect of Feedstock Chemistry and Melt Pool Dynamics on Realizing Superior Strength and Surface Quality in Additively Manufactured Ultra-High Strength Steels
No full textAdditive manufacturing (AM) methods generally utilize a layer-by-layer process, fabricating parts from the bottom up which differs from conventional subtractive manufacturing methods. The current focus of AM development involves the production of complex, functional parts. Due to an increase in demand from industries such as aerospace, biomedical and automotive, metal AM has become increasingly popular. Laser powder bed fusion (L-PBF) is widely regarded as the most versatile metal AM process, utilizing high energy density laser to selectively melt powder particles into highly intricate designs.
Laser powder bed fusion (L-PBF) of a newly developed high strength steel known as AF96 has received notable attention due to its unique microstructure and superior mechanical properties. The current study investigates the influence of initial alloy carbon content and decarburization on the mechanical properties of AF96 fabricated via L-PBF. A process parameter development study was first performed to determine optimal processing parameters that result in near defect-free as-printed parts. Test specimens were then fabricated using optimized parameter combinations for mechanical and microstructural characterization. This process was completed for three compositions of AF96 powder containing varying amounts of initial carbon content. Preliminary results show a significant increase in both yield strength and ultimate tensile strength with increasing initial carbon content.
Spatter, an inherent by-product of conventional laser welding, DED, and L-PBF (Laser Powder Bed Fusion), significantly impacts part quality. This research investigates spatter's mechanisms, effects, and in-situ monitoring techniques within the context of L-PBF. Spatter, classified into droplet (hot) and powder (cold) types, originates from vapor-driven entrainment and recoil pressure, impacting surface quality and creating internal flaws. Spatter redeposition during printing leads to recoater impediment, defect formation, and porosity, affecting mechanical properties and surface roughness. In-situ monitoring techniques encompass visible-light high-speed camera imaging, Schlieren video imaging, X-ray video imaging, and infrared video imaging, each revealing various aspects of spatter behavior. A specialized visible-light high-speed camera system for EOS M290 L-PBF, developed for this study, provides insights into spatter ejection behavior. Technical challenges in camera operation and video acquisition were addressed, achieving successful high-speed video imaging capturing spatter movement. Optical microscopy analysis of L-PBF-fabricated AF96-29 cubes reveals varied surface qualities, correlating with spatter distribution in different printability map regions. This study underscores the complexities of spatter behavior, its detrimental effects, and the significance of tailored in-situ monitoring techniques for understanding and mitigating spatter-related issues in L-PBF
Influence of Saccharomyces cerevisiae CNCM I-1077 on the Intestinal Environment, Gut Permeability, and Markers of Systemic Inflammation in Horses Fed a High-Starch Diet
No full textThirty mature Quarter Horse geldings were used in a completely randomized 32-d study to test the hypotheses that supplemental live Saccharomyces cerevisiae CNCM I-1077 improves apparent digestion, stabilizes the intestinal environment, reduces gut permeability, and decreases inflammation in horses fed a high-starch diet. Horses were stratified by BW, age, and body condition score (BCS) to one of two treatments (n=15/treatment): concentrate formulated with 2g starch ��� kg BW^-1 ��� meal^-1 (CON) or the same concentrate top-dressed with 25 g/d Saccharomyces cerevisiae (SC; 20 billion CFU). Horses were fed individually in stalls every 12h. Between meals, horses were housed in dry-lots with ad libitum access to Coastal bermudagrass hay. On d 0 and 32, BW and BCS were recorded, and blood was collected prior to feeding at 2, 8, 16, and 24h post meal. Samples were analyzed for serum D-lactate, chemokine (CCL2) and cytokine (TNF��) concentrations. Whole blood 16s rRNA sequencing was performed. Fecal samples were obtained on d 0, 16, and 32 prior to feeding and at 8, 16, and 24h post meal; fecal pH and fecal starch were measured. Beginning d 28, intake and total fecal production were recorded over 4-d. There was an effect of treatment on ���BW (P=0.03), with no change in BCS (P=0.97). D-lactate peaked at h 8 on d 0, and CON was greater than SC (P���0.01). On d 32, D-lactate tended to be higher in SC at 16h compared to CON (P<0.10). LogCCL2 and TNF�� declined (P���0.02) across treatments to d 32. Fold change of percent reads from d 0 in bacterial 16s rRNA was not different between treatment groups. On d 0, fecal pH declined to h 16 (P���0.01) in both groups but returned to baseline by 24h. At h 0, CON had lower fecal pH on d 32 than d 0 (P���0.01). Fecal starch was undetectable indicating nearly complete dietary starch digestion. There was no effect of treatment for any measure of intake (P���0.25) or digestibility (P���0.77). High-starch diet reduced fecal pH and increased BW but after 32-d, there was no difference in digestibility, intestinal inflammation, or gut permeability, regardless of SC supplementation
Are Open Contacts Associated with Peri-implant Disease?
No full textAims: This study was conducted to determine if open contacts are associated with peri-implant disease. Also, possible associations concerning the width of an open contact as they relate to disease and food impaction were evaluated.
Material and Methods: A clinical exam was performed including: probing depths, interproximal contact status (open vs. closed), microbial sampling from 16 implants, report or observation of food impaction, and review of existing radiographs. This information was used to determine the implant diagnosis. The microbial samples were studied using qPCR. Spearmann���s correlation test was performed to determine whether any associations around the desired variables could be found.
Results: 44 (22 open contacts/ 22 closed contacts) sequential implants in 25 patients were evaluated in the Texas A&M School of Dentistry���s dental clinics. The prevalence of peri-implant mucositis was 22.7%, and the prevalence of peri-implantitis was 11.4%. No statistically significant associations were found between open contacts and peri-implant health status or rate of food impaction. No statistically significant association was found between food impaction and rates of peri-implant disease as well. The width of an open contact also did not impact the health status of the implants or the rates of food impaction. However, peri-implant disease was associated with elevated levels of Peptostreptococcus micros. Also, there was a positive association between the number of Capnocytophaga species bacteria present and the increased width of open contact.
Conclusions: Within the confines of this study open contacts around dental implants are not associated with peri-implant disease. There is a noted increase of Peptostreptococcus micros around diseased dental implants. More research is necessary to corroborate these findings
Exploiting Plant-Based Protein Functionalities Through Tannin-Mediated Structural Modification and Application as Texturized Vegetable Protein (TVP��) and Edible Film
No full textThe surging global demand for alternative diverse and sustainable sources has been driven by an increasing global population and a growing number of health-conscious consumers. The current trend has caused a significant focus on pulse proteins as a potential alternative, primarily because of their exceptional nutritional profile and the reduced consumer concerns surrounding allergens, and negative perception. As a result, research initiatives are now underway to improve the functionality and value of pulse proteins, with a specific goal of enhancing their role as alternatives meat source as texturized vegetable proteins (TVP��) and edible films. The major obstacle for pulse proteins is their limited effectiveness when compared to conventional sources. Pulse proteins face limited competitiveness due to high solubility and low cross-linking propensity in comparison to traditional meat sources. This stems from their high solubility and a low propensity for cross-linking, which affects their ability to imitate the texture and structure of the meat. To address these areas, this research primarily revolves around the utilization of polymeric polyphenols, specifically proanthocyanidins (PA), to modify and enhance the structure and rheological properties of pulse proteins. The fundamental premise of this approach is to harness the abundant biofunctional polyphenols found in tannins to fundamentally alter the characteristics of pulse proteins. This alteration aims to improve key attributes such as solubility, water-binding capacity, and texture. The ultimate objective is to make pulse proteins highly functional and competitive as meat substitutes and edible films, thereby meeting the demands of health-conscious consumers while addressing concerns about the sustainability of food production systems.
In this research, we investigated the effect of PA on pulse protein rheology and film properties and assessed the mechanisms behind these interactions. The main focus of this research was to develop texturized pulse proteins (TXVP) utilizing a twin-screw extruder using pea proteins (PP), lentil proteins (LP), faba bean proteins (FP) and conduct post testing with these texturized proteins extrudates. Commercial pea protein (77.4% protein), lentil protein (81.9% protein), and faba bean protein (80.9 % protein) were prepared for production of texturized vegetable proteins and soy proteins (SP, 66.5% protein) was used as a control.
Polymeric PA from sorghum (mean degree of polymerization, mDP 19.5) dramatically strengthened pulse protein, e.g., at 2.5 mg/g flour. The network of the texturized proteins from the two pulses (pea and faba) also exhibited increased hardness and springiness, which are indications of the protein crosslinking and holding together better with increasing levels of PA. Lentil proteins did not texturize and that of soy was not showing consistent properties. Polymeric surface hydrophobicity of protein (pea and faba) was reduced by PA (69 ��� 75% vs control).
To evaluate the opposite behavior of lentil protein during extrusion (did not texturized because of its high-water holding capacity), lentil protein and pea protein were utilized for making edible films. Polymeric PA increased lentil protein film strength (e.g., at 2.5 mg/g protein, force to extend was 2.3X greater than control without reduced extensibility). Thus, PA may improve lentil film flexibility and structural integrity. Overall evidence indicates PA complexed with pulse protein by hydrophobic interaction and hydrogen bonding. In conclusion, the research outlined in this study holds the promise of transforming pulse proteins into versatile and sustainable alternatives to traditional meat sources and edible films. By enhancing their functionality and competitiveness, this work seeks to contribute to the global effort to promote sustainable food production and meet the evolving dietary preferences of a growing population
Influence of Microstructural Components on Hydrogen Embrittlement in Alloy 718: Insights from Friction Stir Processing and Additive Manufacturing
No full textHydrogen can cause severe embrittlement of high-strength metal alloys. Nickel alloy 718, a high-strength and corrosion-resistant alloy widely used in the aerospace and oil & gas industries, is highly susceptible to hydrogen embrittlement (HE). The premise of this work is to explore thermomechanical processing to obtain unique fine-grained microstructures in alloy 718. By employing electrochemical hydrogen charging, it aims to advance the understanding of the role secondary phases and grain boundaries (GBs) play in HE behavior. The overarching goal is to identify and propose strategies for the design of HE-resistant alloys.
Firstly, the effect of grain size and precipitates on HE susceptibility is investigated. Under tensile loading, the friction-stir processed and aged (FSP-A) condition with refined grains and precipitates showed substantially reduced HE susceptibility with 12.6% loss of ductility due to hydrogen as measured by reduction in area compared to the coarse grained peak-aged (PA) condition, which lost 29.9%. However, the FSP (with fine grains) and solution-treated (ST, with coarse grains) conditions prior to being aged display similar susceptibility to HE, despite higher hydrogen uptake in the former. The finding that microstructures with refined grains absorb more hydrogen yet have similar or reduced HE susceptibility, demonstrates their HE resistant character.
Secondly, the role of GB character distribution on HE susceptibility in fine-grained alloy 718 was evaluated. Three FSP cases, processed at rotational speeds of 200, 250, and 300 rpm, respectively, with a constant feed rate of 50 mm/min, produced 57%, 65%, and 53% high angle GBs (HAGBs), respectively. Tensile test results show that a high fraction of HAGBs in the microstructure can be correlated to higher HE susceptibility.
Finally, microstructures and properties of alloy 718 produced by selective laser melting (SLM) and subjected to heat treatments (HTs) were investigated. The as-printed material contained 4.7��0.8% volume fraction of the Laves phase, which is reduced to 0.2��0.1% after HT at 1150��C for 2 h. Tailored produced mechanical properties meeting API A6CRA requirements. HE behavior of SLM alloy 718 was similar to wrought alloy 718, with as-printed and aged conditions exhibiting higher HE susceptibility than solutionized conditions, likely by similar HE mechanisms