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Lanthanide and Actinide Schiff-Base Complexes
Get PDFAs concerns about climate change grow, so does the interest in alternative green energy sources such as solar, wind, and nuclear energy. While in many ways, nuclear energy is the most developed technology that can meet the current energy needs of the United States, nuclear energy is still considered controversial. The efficiency of the nuclear fuel cycle can be improved by finding more cost-effective ways to recycle the fissile uranium from neutron poisonous fission products, the worst of which are the difficult to separate lanthanide elements. Separating the intermediate-lived and stable fission products from the long-lived fission products to reduce the volume of spent fuel stored in geological waste repositories is a crucial challenge that continues to be researched. Towards these goals, the development of ligand systems that can selectively sense, bind, or extract uranium from mixtures of lanthanides and actinides are of particular interest. In this work, a redox-active backbone was used to synthesize a class of new Schiff-base ligands herein named “pyrasal” that feature a pyrazine ring. These pyrasal ligands were explored with cerium, thorium and uranyl. Cerium showed a switch in coordination geometry due to just changes in pH and temperature. Thorium complexes with pyrasal were planar and showed much less fluorescence than the comparable naphthylsalophen thorium complexes. With uranyl, pyrasal ligands facilitated the lengthening of the U=O bond and enhanced the basicity of the oxo ligand allowing for the oxo ligand to act as a hydrogen bond acceptor. Indeed, the lengthening of the U=O bond was seen to be strongly affected by the solvent choice. Finally, a bis-salophen ligand was synthesized from the condensation of 3,3-diaminobenzidine and 4-(N,N-diethylamino)salicylaldehyde. When the bis-salophen ligand is complexed with thorium nitrate in a 1:1 ratio, then a unique structure herein named “thorium delta” is formed. Thorium deltas are discrete molecular structures with a triangular shape, 3-to-3 metal-to-ligand ratio, and racemic Δ,Δ,Δ-chirality. The center of the structure has a pore that can be used to bind anions and showed affinity for chloride anions
Persistence Beyond Placement (AB 705): An Analysis of Re-Enrollment Patterns Among California Community College Students Failing Transfer-Level Mathematics
No full textIn 2017, California passed Assembly Bill 705, which transformed developmental education in the California community college system. A significant aspect of this transformational legislation was greater access to transfer-level math by leveraging high school transcript data and eliminating assessment testing. A comprehensive review of developmental education in the California community college system and the historical context of developmental education that led to the passage of AB 705 is explained. This study examined re-enrollment patterns of students who did not successfully complete transfer-level math on their first attempt at a large suburban community college in southern California. With a focus on students who did not successfully complete transfer-level mathematics, ethnicity, sex, major, and the total number of units attempted were the predictor variables analyzed in this study. In exploring the connection between re-enrollment trends, Wang’s Theory of Momentum provided a theoretical foundation that highlighted academic motivation in achieving key academic milestones such as successfully completing transfer-level math, especially in STEM (Science, Technology, Engineering, and Mathematics) courses. A quantitative research methodology included descriptive statistics of the student cohort, re-enrollment data, and logistic regression to analyze student data over two academic years (summer 2022 through spring 2024). The statistical analysis revealed several key findings, such as the higher likelihood of STEM students re-enrolling in transfer-level math compared to non-STEM students and disparities in re-enrollment rates by ethnicity. The study concluded by discussing the broader implications for higher education and recommendations for the California community college system to improve student success in transfer-level math
Qualitative Study on the Perspective of Rural Inhabitants Facing the Agricultural Land Conflict in Antioquia, colombia
Get PDFThis qualitative case study explored, identified, and described the experiences, reflections, and expectations of 13 participants of rural origin from Northwest Antioquia, Colombia, regarding the agrarian conflict understood as dispossession, access, and accumulation of land, forced displacement, and rural development programs to alleviate rural poverty and violence. Through in-depth interviews, study participants revealed the deep impact that the agrarian conflict has had on the lives of smallholder farmers. The participants indicated that they lacked essential information regarding important issues such as agrarian reform and other channels of participation in land restitution, as well as profound feelings of distrust and dissatisfaction towards agrarian policy and reparation for victims of the armed conflict. The findings indicated a critical lack of confidence in the government and public institutions, highlighting an urgency for state transparency in the development of rural communities and the reconstruction of the countryside during the current post-conflict phase
Grid Forming Inverter Control for Inverter Based Resources (IBR) Dominated Power Grid
Get PDFThe rapid growth of Inverter-Based Resources (IBR) like solar and wind energy is creating challenges for power grids. As traditional synchronous generators become less common, power systems have less inertia, making it harder to keep the frequency stable during disruptions. The grid's ability to handle faults is also weaker, which affects reliable operation. These problems show the need for advanced solutions to keep the grid stable when more renewable energy is used. Grid-Forming (GFM) inverters are a promising solution because they can behave like traditional generators, providing virtual inertia, voltage control, and frequency support to help maintain grid stability.
Given these challenges, there is an urgent requirement for innovative solutions to enhance grid stability as the penetration of renewable generations is growing continuously. This thesis focuses on developing a GFM inverter control strategy to improve grid performance with high IBR levels. It specifically considers a p-f droop-controlled GFM inverter for large power systems dominated by reactance. The proposed control approach is tested using the Vehicle-to-Grid (V2G) capability of an Electric Vehicle (EV), where the GFM inverter helps stabilize the power system under different abnormal conditions. The results show that the GFM inverter improves stability, supports frequency regulation, and makes it easier to integrate renewable energy. This work helps advance the use of GFM inverters as a key technology for building resilient and sustainable power systems
Agronomic Impacts on Cotton (Gossypium hirsutum L.) Industrial Performance
Get PDFCotton (Gossypium hirsutum) is a natural fiber, that exhibits natural variation in fiber quality which can impact its performance as a raw material in industrial settings. Different genetics between varieties impacts fiber quality, yarn spinning, and yarn quality. The same can be said for environmental effects, which are often greater than genetic effects on variation in a production setting. Three different experiments were conducted to develop strategies for building actionable data from commercial scale spinning trials. These experiments focus on questions around environmental impacts on the fiber at various stages of cotton production. The experiments focus on cotton physiology, how late season cool temperatures impact boll development; post-harvest processing of fiber, how growing environment affects ginning energy use; and yarn spinning, how environment effects yarn spinning production.
In the first experiment, a set of 54 30-boll bulked samples were taken in Etter, Texas and 427 single boll samples were taken in New Deal, Texas in 2020 before, during, and after a non-freezing cold front. Bolls were sampled from nodes 5, 8, and 11 to assess fruit at different maturity stages. Yield and AFIS fiber quality data show that fiber development within the boll continues despite the cool temperatures.
In order to assess the effects of environment on the amount of energy needed to gin cotton, 86 samples grown from 2020-2023 were assessed. Power data was logged for five different motors on a cotton gin: the fan, seed cotton cleaner cylinders, seed cotton cleaner saws, the power roll, and the gin saw. Analysis of energy used showed that the energy required to gin the cotton is affected by the growing environment. A life cycle assessment (LCA) showed that these differences can potentially result in negative environmental impacts.
Growing environment also plays a role in yarn spinning and quality. A set of 81 different cotton samples, grown between 2021 and 2023, were grown and harvested using commercial scale practices, and then spun into two different sizes of yarn: a coarser 18Ne yarn and a finer 30Ne yarn. While there were differences found in the yarn quality between the different years and locations, there were also many bales that did not spin using the prevailing spinning protocol. An increased level of twist was applied to each yarn size, 3.64 to 4.00, in order to evaluate the importance of accounting for twist in spinning trials. The higher twist allows for lower quality cotton to be able to spin and enables comparisons to be made across years, even in the highly variable growing environment in West Texas. While agronomic elements are suspected as the primary source of variation, it is also necessary to consider the wear of spinning equipment, so a spinning check bale was introduced in 2021 and was analyzed for fiber quality, spun, and analyzed for yarn quality alongside the samples every year. This check bale exhibited a consistent spinning performance, suggesting agronomic effects are the primary cause of differences seen in the spinning trials.
The desired traits of cotton are determined in the field, and the environment plays a large role in the outcomes of quality and efficiency during processing. This research lays the foundation for building a wider body of research on the agronomic effects on fiber quality built around a key resource, the Texas High Plains commercial scale spinning trials
Protective Effects of Curcumin on Hepatic Steatosis in High Fat-Fed Obese Mice
No full textIntroduction and hypothesis: Metabolic dysfunction-associated fatty liver disease (MAFLD) is a chronic disorder marked by liver inflammation, lipid accumulation, and oxidative stress. MAFLD is often linked to adiposity and metabolic syndrome. Our previous research suggests the curcumin, a naturally occurring polyphenol found in turmeric, has protective metabolic effects in dietary obesity. The objective of this study was to explore the effects and mediating mechanisms of curcumin in improving inflammation and lipid metabolism in the liver of high-fat (HF)-induced obese mice and in cultured hepatoma cells. We hypothesized that curcumin would reduce high-fat diet-induced hepatic lipid synthesis and inflammation in obese mice and HF-induced inflammation in cultured hepatoma cells.
Methods and approaches: Five-week-old male B6 mice were randomly assigned into either a HF diet (45% kcal fat) or HF diet with curcumin (HFC, 0.4% w/w curcumin) for 13 weeks. At the end of the intervention, livers were harvested and used for histological analyses and subsequent gene expression analysis using qPCR and RNA sequencing. Moreover, hepatoma Hep-G2 cells were treated with palmitic acid to induce inflammation and then with curcumin or its metabolites (tetrahydro curcumin and curcumin-o-glucuronide); media were collected for cytokine analyses by immunoassays and cells were harvested for gene expression analyses by qPCR. All data were analyzed using GraphPad Prism Software (v10.0.3).
Results: Curcumin significantly reduced the expression of inflammatory genes in liver, such as the toll-like receptor-4 (TLR-4, p<0.05). Transcriptome analyses by RNA Seq revealed 631 differentially expressed genes (FDR-adjusted p value ≤ 0.05, fold change ≥ 2), with 263 downregulated and 368 upregulated genes. Curcumin increased gene expression of several pathways including fatty acid-beta oxidation (z = 1.342), lipid metabolism regulation by peroxisome proliferator-activated receptor (Ppar) alpha (z = 2.236), and downregulated lipopolysaccharide /Interleukin-1 mediated inhibition of retinoid x receptor (Rxr) pathways (z = -1.633). In the in vitro HepG2 cell study with palmitic acid induction, curcumin, and its metabolites did not affect fatty acid synthesis such as the acetyl CoA carboxylase alpha (Acaca), or inflammatory mRNA levels including interleukin-8 (Il-8).
Conclusion: Our results indicate protective metabolic effects of curcumin in reducing specific markers of lipid accumulation and inflammation in the liver. These findings suggest potential therapeutic benefits of curcumin in MAFLD and warrant further mechanistic studies in animals and cells as well as future clinical studies in people with obesity
Spatio-temporal variations of air pollutants and human health exposure impacts during 2023 haze through respiratory deposition analysis in Delhi-NCR, India
No full textThis study investigated the impacts of the 2023 haze episode on air quality and respiratory health in the Delhi-National Capital Region (Delhi-NCR), India. Monitoring data for PM2.5, PM10, NO2, NH3, SO2, O3, and CO were collected at four representative sites (Delhi, Gurugram, Greater Noida, and Ghaziabad) and analyzed for spatiotemporal variations. Fire hotspot analysis, meteorological data, and backward trajectory analysis modeling revealed the elevated pollution levels during the haze episode were attributable to increased local emissions coupled with the transport of pollutants from biomass burning in neighboring states. To assess health risks, the International Commission on Radiological Protection (ICRP) modeling was used to estimate respiratory deposition dose (RDD) of PM2.5 and PM10 in the head airway (HA), tracheobronchial (TB), and alveolar (AL) regions for both males and females under three modes of metabolic activities of seated, walking and exercise. The results indicated a substantial increase in the total RDD (sum of HA, TB, and AL regions) across all sites, genders, and activity levels. For instance, PM2.5 RDD in Delhi increased from 1.03 to 2.44 µg/min during the haze period for males under seated activity and from 0.72 to 1.69 µg/min for females. Overall, the study estimated a 130 % increase in health risk during the haze period across all activity levels and genders
Introduction to advancements in synthesis of high-performance materials from Nature’s building blocks
No full textThe growing environmental concerns associated with traditional petroleum-based polymers have intensified the search for sustainable alternatives. This themed collection highlights innovative approaches in polymer science that prioritize sustainability without compromising performance. The featured articles encompass a spectrum of strategies, from the utilization of bio-derived monomers and biopolymers to the engineering of dynamic, self-healing materials
Microbial Dynamics of Beef on Dairy Calves During the Neonatal Period
Get PDFGut microbiome colonization in newborn calves is key for long-term health,
welfare, and productivity across a lifetime. This study aimed to investigate the
impact of colostrum feeding on intestinal microbiota dynamics of beef-on-dairy
calves during the first 21 days of life. Animals were randomly assigned to a
colostrum-fed (n = 12) or a colostrum-deprived (n = 12) group. The colostrum-fed
group received 2.8 liters of high-quality colostrum within six hours after birth. At
eight days of age, intestinal inflammation was induced via oral inoculation with
Salmonella Typhimurium in six calves from each group. Meconium and rectal
swabs were collected at birth (day 0), days 7, 8, 9, 10, 11, 14, and 21 of age.
Microbiota diversity was analyzed based on 16S rRNA sequencing. Calves that
received colostrum had greater microbial richness and diversity compared to
colostrum-deprived calves. In response to the Salmonella Typhimurium
inoculation, the diversity changes were more prominent in the colostrum-deprived
compared to the colostrum-fed group. Our study highlights the importance of
maternal colostrum in influencing a resilient and diverse intestinal microbiota
composition, which in turn decreases the occurrence and intensity of enteric
diseases in beef-on-dairy calves before weaning