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High-throughput design of high-performance lightweight high-entropy alloys
Get PDFDeveloping affordable and light high-temperature materials alternative to Ni-base superalloys has significantly increased the efforts in designing advanced ferritic superalloys. However, currently developed ferritic superalloys still exhibit low high-temperature strengths, which limits their usage. Here we use a CALPHAD-based high-throughput computational method to design light, strong, and low-cost high-entropy alloys for elevated-temperature applications. Through the high-throughput screening, precipitation-strengthened lightweight high-entropy alloys are discovered from thousands of initial compositions, which exhibit enhanced strengths compared to other counterparts at room and elevated temperatures. The experimental and theoretical understanding of both successful and failed cases in their strengthening mechanisms and order-disorder transitions further improves the accuracy of the thermodynamic database of the discovered alloy system. This study shows that integrating high-throughput screening, multiscale modeling, and experimental validation proves to be efficient and useful in accelerating the discovery of advanced precipitation-strengthened structural materials tuned by the high-entropy alloy concept
Antibacterial Properties of Citric Acid/β-Alanine Carbon Dots against Gram-Negative Bacteria
Get PDFWhile multi-drug resistance in bacteria is an emerging concern in public health, using carbon dots (CDs) as a new source of antimicrobial activity is gaining popularity due to their antimicrobial and non-toxic properties. Here we prepared carbon dots from citric acid and β-alanine and demonstrated their ability to inhibit the growth of diverse groups of Gram-negative bacteria, including E. coli, Salmonella, Pseudomonas, Agrobacterium, and Pectobacterium species. Carbon dots were prepared using a one-pot, three-minute synthesis process in a commercial microwave oven (700 W). The antibacterial activity of these CDs was studied using the well-diffusion method, and their minimal inhibitory concentration was determined by exposing bacterial cells for 20 h to different concentrations of CDs ranging from 0.5 to 10 mg/mL. Our finding indicates that these CDs can be an effective alternative to commercially available antibiotics. We also demonstrated the minimum incubation time required for complete inhibition of bacterial growth, which varied depending on bacterial species. With 15-min incubation time, A. tumefaciens and P. aeruginosa were the most sensitive strains, whereas E. coli and S. enterica were the most resistant bacterial strains requiring over 20 h incubation with CDs
Economic Sustainability and Multiple Risk Management Strategies: Examining Interlinked Decisions of Small American Farms
Get PDFEconomic viability of small farms and farming businesses depends on multiple factors. These farms have limited production and financial resources to maintain their operation. Therefore, to sustain farming, adopting appropriate risk management strategies is a pivotal decision for small farmers. We surveyed Tennessee’s small farms and utilized multivariate probit models to study factors influencing the adoption of various risk management strategies. Our findings suggest that the decisions related to the adoption of risk management strategies are significantly interlinked. Along with factors representing the operator’s age, education, and farm operator’s income and land holdings, we also found that the government incentives (payments), smartphones, and farmers’ continuation plan significantly influence the strategic decisions of adopting risk management strategies
Subterranean movement inferred by temporary emigration in Barton Springs salamanders (Eurycea sosorum)
Get PDFMovement behavior is an important aspect of animal ecology but is challenging to study in species that are unobservable for some portion of their lives, such as those inhabiting subterranean environments. Using four years of robust-design capture-recapture data, we examined the probability of movement into subterranean habitat by a population of endangered Barton Springs salamanders (Eurycea sosorum), a species that inhabits both surface and subterranean groundwater habitats. We tested the effects of environmental variables and body size on survival and temporary emigration, using the latter as a measure of subterranean habitat use. Based on 2,046 observations of 1,578 individuals, we found that temporary emigration was higher for larger salamanders, 79% of which temporarily emigrated into subterranean habitat between primary sampling intervals, on average. Body size was a better predictor of temporary emigration and survival compared to environmental covariates, although coefficients from lower ranked models suggested turbidity and dissolved oxygen may influence salamander movement between the surface and subsurface. Surface population dynamics are partly driven by movement below ground and therefore surface abundance estimates represent a fraction of the superpopulation. As such, while surface habitat management remains an important conservation strategy for this species, periodic declines in apparent surface abundance do not necessarily indicate declines of the superpopulation associated with the spring habitat
Biofilm Formation and Pressure-Based Pasteurization of Bacterial Spores and Foodborne Pathogens of Public Health Concern as Affected by Bacteriocin and Bactericidal Compounds
No full textPathogens of public health concern associated with food and agricultural commodities are global and national challenges. Based on epidemiological studies of the U.S. Centers for Disease Control and Prevention, in a typical every, 48 million people become sick from foodborne diseases, 128,000 are hospitalized, and 3,000 die. The first study of this dissertation utilized a six‐strain mixture of E. coli O157:H7 that were exposed to 0 to 9 minutes of hydrostatic pressure (400 MPa) and thymol for the experiments of the inoculated pathogen in a 10% beef homogenate. Pathogen counts were reduced to 0.67 ± 0.2 logs CFU/mL after 6 minutes of pressure treatment. Thymol and mild heat (40 °C) and pressure treatments after 3, 6, and 9 minutes reduced (p \u3c 0.05) the pathogen by 2.1, 2.5, and 3.1 logs CFU/mL, respectively. The second study of this dissertation is dedicated to controlling Listeria monocytogenes using mild heat with elevated hydrostatic pressure at 400 MPa and nisin under buffered conditions. A pathogen mixture was exposed to 0 to 9 minutes of treatments at 4 and 40 °C. This synergism with nisin faded away (p ≥ 0.05) as the treatment time for thermal, high-pressure, and thermal-assisted pressure processing increased and was efficacious (p \u3c 0.05) for treatments \u3c 3 minutes. The third study of this dissertation was designed to investigate biofilm formation by ten strains of Salmonella serovars for up to 21 days at 25 °C. Mature biofilms were then treated with carvacrol, quaternary ammonium, and water. Planktonic cells exhibited greater sensitivity to the tested antimicrobials compared to sessile cells of one-, two-, and three-week mature biofilms. The last study of this dissertation was designed to study the effects of elevated hydrostatic pressure for the inactivation of three indicator spore-forming bacteria. Elevated hydrostatic pressure at 650 MPa and 50 °C were applied for 0, 3, 7, and 11 minutes with and without nisin, lysozyme, lactic acid, and Citricidal™. We observed that a well-design pressure treatment synergized with mild heat and bacteriocin and bactericidal compounds could reduce up to \u3e 4 logs CFU/mL (i.e. \u3e 99.99%) of bacterial endospores
Science Forum: A community-led initiative for training in reproducible research
Get PDFOpen and reproducible research practices increase the reusability and impact of scientific research. The reproducibility of research results is influenced by many factors, most of which can be addressed by improved education and training. Here we describe how workshops developed by the Reproducibility for Everyone (R4E) initiative can be customized to provide researchers at all career stages and across most disciplines with education and training in reproducible research practices. The R4E initiative, which is led by volunteers, has reached more than 3000 researchers worldwide to date, and all workshop materials, including accompanying resources, are available under a CC-BY 4.0 license at https://www.repro4everyone.org/
A Correlational Study of Teacher Quality and Student Achievement in 4th Grade English Language Arts Classes
No full textThis study focused on determining the aspects of the relationship between teacher quality and student achievement. These teacher quality measurements were framed around overall evaluation scores, teacher experience, teacher certifications, and teacher degree levels. This study investigated whether there was a correlation between teacher quality and student achievement at three elementary schools in Metropolitan Nashville Public Schools. A quantitative correlational research design was utilized for this study. A statistical analysis was completed to determine the correlation between student achievement results for the statewide testing in the area of 4th grade English Language Arts and the following teacher quality components: teacher evaluation scores, teacher experience, teacher certification, and teacher degree level. The study consisted of four Pearson product-moment correlation coefficient® tests. The student data included a total number of 379 students who took the state 4th Grade TNReady Assessment for the 2017–2018 and 2018–2019 school years. The results revealed a statistically significant correlation between teacher degree levels and student achievement, particularly for teachers with a specialist degree. There was an increase in the student mean scores for teachers with a specialist degree compared to student scores of teachers who possessed a bachelor’s or master’s degree. This study has implications for future research on teacher quality and student achievement regarding teacher degree level. If school districts and principals continue to investigate the relationship between the student achievement of students and assignment to teachers with a specialist degree in other elementary subjects such as math and science, it may be beneficial for teachers to pursue advanced degrees
Root Responses to Aluminum Stress in Cowpea (Vigna unguiculata L.)
No full textCowpea is a crop that is widely grown in areas that are having issues with food scarcity, such as sub – Saharan Africa, Southern Asia, South America, and in the Southeastern United States. This makes research on cowpea improvement a likely way to supply the increased demand for food products in these areas. Aluminum toxicity is one of the most important abiotic stresses limiting cowpea production in the world, resulting in poor root growth and changes in root morphology leading to less efficient water and nutrient uptake. Identification of cultivars with aluminum toxicity stress tolerance should be a main objective of cowpea improvement programs in the Southeastern USA where aluminum toxic soils are common. Two hydroponics experiments were carried out to administer aluminum to cowpea plants and determine the effects of toxicity on cowpea root systems. Each hydroponic experiment used the same nutrient solution for control and added 50µM of AlCl3 for treatment. Additionally, two cowpea genotypes (Dixie Lee and Queen Anne) were identified as being suitable for germination in growth chamber transfer to hydroponics solution. Seeds were germinated on petri dishes on autoclaved paper towels prior to transfer to hydroponics tanks. WinRhizo was used to analyze root characteristics over a range of days (8 days in experiment 1 and 5 days in experiment 2). Eight root growth characteristics were looked at to determine root responses to aluminum: root volume (VOL), root surface area (SA), number of crosses (NCROS), number of forks (NFORKS), root length (LEN), average root diameter (AVGD), and projected root area (PA). It was found that response differed between the two experiments. The first experiment resulted in root thickening in cowpea grown in the aluminum hydroponic solution, a result consistent with other plants. The second experiment found that root growth was not inhibited in the aluminum hydroponics solution. RNA was then extracted from lateral roots and analyzed for quality and quantity to later be used in RNA-seq for aluminum stress resistance candidate genes. The results from the two experiments can be used to guide further research and analysis of cowpea responses to aluminum in hydroponic solution
Palladium-Catalyzed Unprecedented Cross-Coupling of Mixed Phenols and Halides for the Synthesis of Aromatic Ethers
No full textPhenolic compounds present in medicinal and edible plants such as, flavonoids, chalcones, coumarins, quinones and phenolic acids. The antioxidant potential of phenolic compounds show potent activities for cancer prevention and its treatment. Per green chemistry point of view, cascade (tandem) reactions are ideal techniques in organic synthesis for building complex structures. Cascade techniques sometimes been observed in coupling reactions under mild conditions with tolerance of multifunctional groups. It will be interesting to find a cascade type reaction to synthesize polyphenolic ethers. This research project focusses in achieving a new cross-coupling method for establishing polyphenolic ethers from mixed phenols and halides in the presence of palladium catalyst