• Electronic structure of confined carbyne from joint wavelength-dependent resonant Raman spectroscopy and density functional theory investigations

      Martinati, Miles; Wenseleers, Wim; Shi, Lei; Pratik, Saied Md; Rohringer, Philip; Cui, Weili; Pichler, Thomas; Coropceanu, Veaceslav; Brédas, Jean-Luc; Cambré, Sofie; et al. (Elsevier BV, 2022-04)
      Carbyne, i.e. an infinitely long linear carbon chain (LCC), has been at the focus of a lot of research for quite a while, yet its optical, electronic, and vibrational properties have only recently started to become accessible experimentally thanks to its synthesis inside carbon nanotubes (CNTs). While the role of the host CNT in determining the optical gap of the LCCs has been studied previously, little is known about the excited states of such ultralong LCCs. In this work, we employ the selectivity of wavelength-dependent resonant Raman spectroscopy to investigate the excited states of ultralong LCCs encapsulated inside double-walled CNTs. In addition to the optical gap, the Raman resonance profile shows three additional resonances. Corroborated with DFT calculations on LCCs with up to 100 carbon atoms, we assign these resonances to a vibronic series of a different electronic state. Indeed, the calculations predict the existence of two optically allowed electronic states separated by an energy of 0.14–0.22 eV in the limit of an infinite chain, in agreement with the experimental results. Furthermore, among these two states, the one with highest energy is also characterized by the largest electron-vibration couplings, which explains the corresponding vibronic series of overtones.
    • Influential crash conditions leading to injury differences experienced by female and male drivers

      Ryan, Alyssa; Knodler, Michael; Department of Civil and Architectural Engineering and Mechanics, University of Arizona (Elsevier BV, 2022-03)
      Introduction Robust occupant protection is critical for the longevity and quality of life of the diverse driving population. Studies have shown that the vehicle crash testing process has greatly assisted in decreasing the severity of injuries experienced by occupants. However, female occupants are not equitably accounted for in the current testing processes while experiencing a significantly increased risk of higher severity injuries compared to male occupants in comparable crash conditions. Given the increased safety concern for female occupants, it is critical to investigate the conditions that result in injuries occurring in specific locations in cases of female occupants compared to male occupants. Methods In this study, an investigation is made to uncover potential influential crash conditions that lead to injury location differences experienced by female and male drivers using a novel linked dataset of emergency medical services and crash data. Logistic regression methods were used to develop robust analyses. Results The results revealed that female and male drivers experience injuries in different locations to a significant degree depending upon vehicle model year, airbag deployment, and driver age when considering all crash types. The results included the finding that as vehicle model year increases, neck injury risk decreases for male drivers while it increases for female drivers. Conclusions This study highlighted the crash conditions and vehicle components that lead to different injury outcomes for female and male drivers. From a policy perspective, the results emphasize the importance of including both representative female and male anthropometry in vehicle testing and design. From a practitioner and research perspective, this study provides the data needed to understand the components of vehicle design that must be further considered to provide optimal occupant protection for the entire driving population, leading to more equitable, positive long-term health outcomes for all drivers.
    • Molecular dynamics simulation of edge crack propagation in single crystalline alpha quartz

      Molaei, Fatemeh; Dept. Mining and Geological Engineering, University of Arizona (Elsevier BV, 2022-03)
      Edge crack propagation of single-crystalline alpha quartz under mode I loading condition was investigated using a molecular dynamics simulation. Five different crack lengths are used to analyze the effects of crack length on each sample's crack growth behavior. The effect of crack length was studied in terms of the material's stress-strain curve, strain energy, fracture toughness, atomic analysis of crack propagation, and crack opening deformation. The results revealed that during tensile loading, the pre-cracked crystalline quartz samples are fractured in a brittle approach. The fracture stress in the pre-cracked sample (40 Å length) is dropped about 70% compared to pristine quartz. Moreover, the effect of loading velocity on the mechanical properties is investigated. According to the findings, maximum stress rises by enhancing the loading velocity, and fracture toughness improves. The fracture surface energy of the single crystalline alpha quartz is calculated, and based on the results, there is a good agreement with experimental data.
    • Temperature and moisture alter organic matter composition across soil fractions

      Cates, Anna M.; Jilling, Andrea; Tfaily, Malak M.; Jackson, Randall D.; Environmental Science, University of Arizona (Elsevier BV, 2022-03)
      Understanding the complex interplay of biotic and abiotic controls on soil organic carbon (SOC) stabilization and aggregate formation is a vital and evolving research field, with implications for C and climate change modeling. Here, we delve into the effects of temperature and moisture treatments on aggregate SOC composition. Aggregate fractions representing different levels of physical protection for SOC were isolated three times during a 6-month incubation with 2x2 factorial temperature and moisture treatments (22 or 30 °C, 45% or 65% water-filled pore space). The chemical composition within each fraction was analyzed using high-resolution Fourier-transform ion cyclotron resonance mass spectrometry (FTICR-MS) to evaluate the prevalence of different classes of C compounds by fraction and temperature and moisture treatments. In addition, a partial least square regression (PLSR) was used to explore potential correlations between relative abundance of C compound classes and C content within aggregate fractions. We found that organic matter in the macro- (>250 µm) and micro-aggregates (53 to 250 µm) was relatively enriched in lipid-, carbohydrates-, and protein–like compounds compared to silt and clay fractions (<53 µm). Organic matter in silt and clay was, on the other hand, relatively enriched in compounds with no specific classification, with overall high aromaticity. Broadly, simpler, low-molecular-weight C storage was altered by both temperature and moisture, while complex C storage was especially altered by moisture, within aggregates. Univariate effects of temperature and moisture on specific compound classes varied by soil fraction, but across fractions temperature increased the relative abundance of condensed- and unsaturated hydrocarbon-, tannin-, and amino sugar-like compounds and decreased the relative abundance of protein-like compounds. Moisture increased tannin-, condensed hydrocarbon-like compounds, and the overall aromaticity, and had the most pronounced effect in fractions occluded within macroaggregates, suggesting that substrate diffusion and pore connectivity within the aggregate environment drive the composition of C protected within aggregates. The PLSR indicated that treatments promoted different compounds to contribute to C accrual. Under dry conditions, condensed hydrocarbon-like compounds were associated with microaggregates, while amino sugar-like compounds were associated with macroaggregates and coarse particulate organic matter (POM), and lipid-like and aliphatic compounds were associated with silt and clay. Temperature effects on PLSR results were most visible in silt and clay fractions, where carbohydrate- and tannin-like compounds were associated with C content. This suggests that warmer conditions under climate change may more substantially alter mineral-associated C content, while changing water regimes will alter C content in physically protected environments, with the most significant changes under cool and moist conditions. Overall, our data reveal distinct resource pools in different climate and aggregate environments, a baseline for our understanding of SOC accrual and soil structure under different conditions. More research into how microbes process physically protected SOC under altered environments may fine-tune our ability to predict soil functions including water behavior and nutrient release. © 2021 The Authors
    • Do people maximize quantiles?

      de Castro, Luciano; Galvao, Antonio F.; Noussair, Charles N.; Qiao, Liang; Department of Economics, University of Arizona (Elsevier BV, 2022-03)
      Quantiles are used for decision making in investment analysis and in the mining, oil and gas industries. However, it is unknown how common quantile-based decision making actually is among typical individual decision makers. This paper describes an experiment that aims to (1) compare how common is decision making based on quantiles relative to expected utility maximization, and (2) estimate risk attitude parameters under the assumption of quantile preferences. The experiment has two parts. In the first part, individuals make pairwise choices between risky lotteries, and the competing models are fitted to the choice data. In the second part, we directly elicit a decision rule from a menu of alternatives. The results show that a quantile preference model outperforms expected utility for 32%–55%, of participants, depending on the metric. The majority of individuals are risk averse, and women are more risk averse than men, under both models.
    • Sinuous channels east of Olympus Mons, Mars: Implications for volcanic, hydrological, and tectonic processes

      Sutton, Sarah S.; Hamilton, Christopher W.; Cataldo, Vincenzo; Williams, David A.; Bleacher, Jacob E.; Lunar and Planetary Laboratory, University of Arizona (Elsevier BV, 2022-03)
      The Late Amazonian volcanic plains east of Olympus Mons contain numerous channels and fossae. Channel formation hypotheses have included volcanic processes, flowing water, or a combination of both. To evaluate these hypotheses, we conducted detailed geomorphological and facies mapping at two sites containing channels and fossae representative of features in the region. Based on our mapping and morphological analyses using high resolution topography and images from HiRISE and CTX data, we classified channels into three types, and fossae into two types. Channel Type 1 and Type 2 are consistent with the morphology of lava channels, however, we found no evidence of channel formation due to thermo-mechanical erosion. Additionally, we calculated the potential for lava to achieve turbulent flow within our two study sites and found it unlikely. Channel Type 3 is consistent with fluvial bedrock erosion, likely sourced from erupted groundwater that entrained regolith into lahar-like flows. Fossae are classified as linear (Type L) or arcuate and branched (Type A). Type L fossae are interpreted to be surface fractures associated with dike emplacement, whereas Type A fossae are interpreted to be surface fractures due to sill emplacement, which may have melted buried ice deposits and generated meltwater floods. Type 1 and Type 2 channels are associated with Type L fossae and fissure-fed effusive eruptions of lava. In contrast, Type 3 channels are co-located with Type A fossae, and are likely due to outbursts of groundwater possibly related to sill emplacement. We attribute the formation and distribution of channels and fossae throughout the plains east of Olympus Mons to be a consequence of the region's evolving states of stress, which are predominantly influenced by the loading of Olympus Mons. © 2021 Elsevier Inc.
    • Mesozoic building of the Eastern Tianshan and East Junggar (NW China) revealed by low-temperature thermochronology

      He, Zhiyuan; Wang, Bo; Glorie, Stijn; Su, Wenbo; Ni, Xinghua; Jepson, Gilby; Liu, Jiashuo; Zhong, Linglin; Gillespie, Jack; De Grave, Johan; et al. (Elsevier BV, 2022-03)
      The Eastern Tianshan and East Junggar orogenic belts are major constituents of the southwestern Central Asian Orogenic Belt. This study applies low-temperature thermochronology to constrain the thermo-tectonic history of these two domains. Apatite fission track (AFT) dating of Paleozoic basement samples from the Eastern Tianshan and East Junggar dominantly yield Cretaceous (∼126–70 Ma) AFT ages, except for two granitic samples from the East Junggar with older ages of ∼239 and ∼157 Ma, respectively. Thermal history modeling reveals that the Eastern Tianshan and southern part of the East Junggar experienced moderate to rapid basement cooling throughout the Cretaceous. We interpret it as a far-field effect of accretion and collision along the south Eurasia margin since the Early Cretaceous. Major faults were reactivated and thus may have played an important role in controlling localized fast uplift and cooling. We also dated seven Mesozoic sandstone samples collected from the eastern margin of the Junggar Basin. The detrital AFT age peaks, together with inverse thermal history modeling of the basement, reveal that the East Junggar underwent late Permian to Early Jurassic cooling episodes. These cooling events are thought to be related to post-orogenic transpression along major faults and distal effect of Qiangtang-Eurasia collision. Combined with already published evidence, our new data suggest that the Eastern Tianshan and East Junggar did not undergo significant exhumation during the Cenozoic.
    • How to decode interstellar messages

      Matessa, Michael; Vakoch, Douglas A.; Lower, Timothy A.; Barkow, Jerome H.; DeVito, Carl L.; Department of Mathematics, University of Arizona (Elsevier BV, 2022-03)
      How can we determine the meaning of a message from a distant civilization if we do not have a common language? This paper presents a general technique and principles for decoding interstellar messages: First, find the dimension of the message. Prime numbers may be useful in determining the proportions of messages. Next, find the symbols. This can be done considering symbol types: delimiters, values, relationships, and functions. Then, find the symbol meanings. Features that can help in determining meaning include sub-symbolic type, redundant symbols, expression consistency, physics ratios, and physics expression patterns. Concepts in this paper can be used when a message from another civilization is received, or they can be used to create messages, which can teach communication theory concepts.
    • Extending the life of water reuse reverse osmosis membranes using chlorination

      Souza-Chaves, Bianca M.; Alhussaini, Mohammed A.; Felix, Varinia; Presson, Luke K.; Betancourt, Walter Q.; Hickenbottom, Kerri L.; Achilli, Andrea; Department of Chemical and Environmental Engineering, University of Arizona; University of Arizona; Water and Energy Sustainable Technology (WEST) Center, University of Arizona; et al. (Elsevier BV, 2022-02)
      Numerous efforts have been made over the years to extend the lifespan of reverse osmosis (RO) membranes. End-of-life RO membranes are periodically replaced and usually discarded in landfills. Periodic membrane modification using chlorination may be an alternative to recover their productivity without compromising process safety. In this research, RO membranes from an engineering-scale ultrafiltration-RO system treating reclaimed water were exposed five times to 2000 ppm-h of chlorine immediately after chemical cleaning. Water, conductivity, ion, and organic permeability coefficients and rejection were related to the chlorine dose. The breakthrough of six naturally occurring viruses with different levels of persistence to wastewater treatment was also monitored. After five chlorine doses, the apparent water permeability was recovered to 1.0–1.5 L m−2 h−1 bar−1, a 3.1-fold increase compared to the end-of-life membranes, with only a 2% decrease in observed salt rejection. Interestingly, apparent conductivity and ion permeability slightly decreased after the first and second chlorine dose, likely because the chlorine removed irreversible fouling/scaling and thus reduced concentration polarization. After the third chlorine dose, as the RO membrane surface oxidized, more monovalent ions permeated through the membrane, while observed divalent ion rejection remained relatively high and constant (>97%). Similarly, the RO permeate dissolved organic carbon concentration and total fluorescence intensity decreased between end-of-life membrane and the second chlorine dose, followed by an increase after the third dose, and only humic substances and building block compounds (<2 kDa) were detected. All viruses were below or near the detection limit, indicating that oxidation did not compromise the integrity of the membrane in its ability to reject virus-sized particles. The results suggest that targeted chlorination may extend RO membrane lifespan by increasing apparent water permeability while maintaining RO-like selectivity.
    • The moderating role of mystical-type experiences on the relationship between existential isolation and meaning in life

      Sielaff, Alex; Horner, Dylan E.; Greenberg, Jeff; Department of Psychology, University of Arizona (Elsevier BV, 2022-02)
      Mystical-type experiences (MTEs) are unique phenomenological experiences that are often reported to induce significant and persisting changes in the experiencer's worldview. Previous research suggests that higher levels of existential isolation (EI) are associated with lower levels of meaning in life (MIL). This study examines the hypothesis that people who have had an MTE (compared with those who have not) will not show such a relationship between EI and MIL. Data from two samples (N = 2055) support the idea that those who have not had an MTE show a negative relationship between EI and MIL while those who have had an MTE show no relationship between EI and MIL. Implications and future directions are discussed.
    • Feasibility and acceptability of testing a menstrual-cycle timed smoking cessation intervention for women of reproductive age (Project Phase): Results of a pilot randomized control trial

      Allen, A; Skobic, I; Bell, M L; Medvescek, K; Allen, S; Collins, B; Nair, U; Department of Family and Community Medicine, College of Medicine – Tucson, University of Arizona; Department of Epidemiology and Biostatistics, Mel and Enid Zuckerman College of Public Health, University of Arizona (Elsevier Ltd, 2022-02)
      Introduction: Menstrual phase influences cigarette smoking-related outcomes. Telephone-based cessation programs (e.g., quitlines) may incorporate the role of the menstrual cycle in an effort to tailor interventions for women. Purpose: The goal of this preliminary randomized clinical trial was to examine the feasibility and acceptability of timing quit date to menstrual phase in women in a quitline setting. Methods: We recruited treatment-seeking women with regular menstrual cycles between the ages of 18–40 years. Participants were randomized to the follicular phase (FP; quit date set 6–8 days post onset of menses) or standard of care (SC; no menstrual timing of quit date). All participants received four weeks of nicotine replacement therapy transdermal patch concurrent with six weeks of telephone-based counseling. We explored self-reported and biochemically-verified seven-day point prevalence abstinence at end-of-treatment and three-month follow-up. Results: Participants (n = 119; FP: n = 58, SC: n = 61) were, on average, 33.4 years old and smoked 13.6 cigarettes/day. The median number of counseling sessions completed was 6 out of 6 available, and 66% of participants completed the intervention. Over 90% of participants reported they would recommend this study to friends/family. Cessation rates did not significantly vary by randomization. Conclusions: Results of this preliminary trial indicate that timing quit date to FP is an acceptable and feasible approach to address smoking cessation in women of reproductive age. While we observed similar smoking cessation rates between groups, this preliminary study was not fully powered to determine efficacy. Therefore, the feasibility and acceptability results indicate that a fully-powered efficacy trial is warranted.
    • Correlation of Electrophysiological and Gene Transcriptional Dysfunctions in Single Cortical Parvalbumin Neurons After Noise Trauma

      Wang, Weihua; Deng, Di; Jenkins, Kyle; Zinsmaier, Alexander K.; Zhou, Qiang; Bao, Shaowen; Department of Physiology, College of Medicine, University of Arizona; Department of Ecology & Evolutionary Biology, University of Arizona (Elsevier BV, 2022-02)
      Parvalbumin-expressing (PV+) interneurons in the sensory cortex form powerful inhibitory synapses on the perisomatic compartments and axon initial segments of excitatory principal neurons (PNs), and perform diverse computational functions. Impaired PV+ interneuron functions have been reported in neural developmental and degenerative disorders. Expression of the unique marker parvalbumin (PV) is often used as a proxy of PV+ interneuron functions. However, it is not entirely clear how PV expression is correlated with PV+ interneuron properties such as spike firing and synaptic transmission. To address this question, we characterized electrophysiological properties of PV+ interneurons in the primary auditory cortex (AI) using whole-cell patch clamp recording, and analyzed the expression of several genes in samples collected from single neurons using the patch pipettes. We found that, after noise induced hearing loss (NIHL), the spike frequency adaptation increased, and the expression of PV, glutamate decarboxylase 67 (GAD67) and Shaw-like potassium channel (KV3.1) decreased in PV+ neurons. In samples prepared from the auditory cortical tissue, the mRNA levels of the target genes were all pairwise correlated. At the single neuron level, however, the expression of PV was significantly correlated with the expression of GAD67, but not KV3.1, maximal spike frequency, or spike frequency adaptation. The expression of KV3.1 was correlated with spike frequency adaptation, but not with the expression of GAD67. These results suggest separate transcriptional regulations of PV/GAD67 vs. KV3.1, both of which are modulated by NIHL.
    • Soil microbial community and abiotic soil properties influence Zn and Cd hyperaccumulation differently in Arabidopsis halleri

      Kushwaha, Priyanka; Neilson, Julia W.; Maier, Raina M.; Babst-Kostecka, Alicja; Department of Environmental Science, The University of Arizona (Elsevier BV, 2022-01)
      Soil contamination with trace metal(loid) elements (TME) is a global concern. This has focused interest on TME-tolerant plants, some of which can hyperaccumulate extraordinary amounts of TME into above-ground tissues, for potential treatment of these soils. However, intra-species variability in TME hyperaccumulation is not yet sufficiently understood to fully harness this potential. Particularly, little is known about the rhizosphere microbial communities associated with hyperaccumulating plants and whether or not they facilitate TME uptake. The aim of this study is to characterize the diversity and structure of Arabidopsis halleri rhizosphere-influenced and background (i.e., non-Arabidopsis) soil microbial communities in four plant populations with contrasting Zn and Cd hyperaccumulation traits, two each from contaminated and uncontaminated sites. Microbial community properties were assessed along with geographic location, climate, abiotic soil properties, and plant parameters to explain variation in Zn and Cd hyperaccumulation. Site type (TME-contaminated vs. uncontaminated) and location explained 44% of bacterial/archaeal and 28% of fungal community variability. A linear discriminant effect size (LEfSe) analysis identified a greater number of taxa defining rhizosphere microbial communities than associated background soils. Further, in TME-contaminated soils, the number of rhizosphere-defining taxa was 6-fold greater than in the background soils. In contrast, the corresponding ratio for uncontaminated sites, was 3 and 1.6 for bacteria/archaea and fungi, respectively. The variables analyzed explained 71% and 76% of the variance in Zn and Cd hyperaccumulation, respectively; however, each hyperaccumulation pattern was associated with different variables. A. halleri rhizosphere fungal richness and diversity associated most strongly with Zn hyperaccumulation, whereas soil Cd and Zn bioavailability had the strongest associations with Cd hyperaccumulation. Our results indicate strong associations between A. halleri TME hyperaccumulation and rhizosphere microbial community properties, a finding that needs to be further explored to optimize phytoremediation technology that is based on hyperaccumulation.
    • Do all facial emojis communicate emotion? The impact of facial emojis on perceived sender emotion and text processing

      Pfeifer, Valeria A.; Armstrong, Emma L.; Lai, Vicky Tzuyin; Department of Psychology, University of Arizona; Cognitive Science Program, University of Arizona (Elsevier BV, 2022-01)
      Facial emojis can express a variety of positive and negative emotions, and are commonly used in digital, written communication. However, little is known about how emojis impact text processing and how different emoji-text combinations give rise to a sender's mental state. In this study, we investigated how facial emojis with positive valence (= happy emojis) and facial emojis with negative valence (= upset emojis) embedded in emotionally ambiguous/neutral text affect the perceived mental state of the sender using ratings (Experiment 1) and the processing of the text messages using Event-Related Potentials (Experiment 2). We predicted that (1) the same text message with happy and upset emojis would convey different sender mental states, and (2) emoji valence would affect the processing of subsequent text in valence-specific ways. Our Experiment 1 results showed that while texts with upset emojis convey specific sender mental states, texts with happy emojis convey positive emotion more generally, with no further differentiation between emojis. In ERPs (Experiment 2), we found that emojis affect subsequent text processing at N400, and emoji valence affects processing downstream at the second word. We concluded that all facial-emojis impact text processing, but happy and upset emojis carry differential social-emotional salience and impact text processing differently when content becomes available.
    • Elevated temperatures drive abiotic and biotic degradation of organic matter in a peat bog under oxic conditions

      AminiTabrizi, Roya; Dontsova, Katerina; Graf Grachet, Nathalia; Tfaily, Malak M.; Department of Environmental Science, The University of Arizona (Elsevier BV, 2022-01)
      Understanding the effects of elevated temperatures on soil organic matter (SOM) decomposition pathways in northern peatlands is central to predicting their fate under future warming. Peatlands role as carbon (C) sink is dependent on both anoxic conditions and low temperatures that limit SOM decomposition. Previous studies have shown that elevated temperatures due to climate change can disrupt peatland's C balance by enhancing SOM decomposition and increasing CO2 emissions. However, little is known about how SOM decomposition pathways change at higher temperatures. Here, we used an integrated research approach to investigate the mechanisms behind enhanced CO2 emissions and SOM decomposition under elevated temperatures of surface peat soil collected from a raised and Sphagnum dominated mid-continental bog (S1 bog) peatland at the Marcel Experimental Forest in Minnesota, USA, incubated under oxic conditions at three different temperatures (4, 21, and 35 °C). Our results indicated that elevated temperatures could destabilize peatland's C pool via a combination of abiotic and biotic processes. In particular, temperature-driven changes in redox conditions can lead to abiotic destabilization of Fe-organic matter (phenol) complexes, previously an underestimated decomposition pathway in peatlands, leading to increased CO2 production and accumulation of polyphenol-like compounds that could further inhibit extracellular enzyme activities and/or fuel the microbial communities with labile compounds. Further, increased temperatures can alter strategies of microbial communities for nutrient acquisition via changes in the activities of extracellular enzymes by priming SOM decomposition, leading to enhanced CO2 emission from peatlands. Therefore, coupled biotic and abiotic processes need to be incorporated into process-based climate models to predict the fate of SOM under elevated temperatures and to project the likely impacts of environmental change on northern peatlands and CO2 emissions.
    • Removal of uranium from contaminated groundwater using monorhamnolipids and ion flotation

      Hogan, David E.; Stolley, Ryan M.; Boxley, Chett; Amistadi, Mary Kay; Maier, Raina M.; Department of Environmental Science, The University of Arizona (Elsevier BV, 2022-01)
      Mining of uranium for defense-related purposes has left a substantial legacy of pollution that threatens human and environmental health. Contaminated waters in the arid southwest are of particular concern, as water resource demand and water scarcity issues become more pronounced. The development of remediation strategies to treat uranium impacted waters will become increasingly vital to meet future water needs. Ion flotation is one technology with the potential to address legacy uranium contamination. The green biosurfactant rhamnolipid has been shown to bind uranium and act as an effective collector in ion flotation. In this study, uranium contaminated groundwater (∼440 μg L−1 U) from the Monument Valley processing site in northeast Arizona was used as a model solution to test the uranium removal efficacy of ion flotation with biosynthetic (bio-mRL) and three synthetic monorhamnolipids with varying hydrophobic chain lengths: Rha-C10-C10, Rha-C12-C12, and Rha-C14-C14. At the groundwater's native pH 8, and at an adjusted pH 7, no uranium was removed from solution by any collector. However, at pH 6.5 bio-mRL and Rha-C10-C10 removed 239.2 μg L−1 and 242.4 μg L−1 of uranium, respectively. By further decreasing the pH to 5.5, bio-mRL was able to reduce the uranium concentration to near or below the Environmental Protection Agency maximum contaminant level of 30 μg L−1. For the Rha-C12-C12 and Rha-C14-C14 collector ligands, decreasing the pH to 7 or below reduced the foam stability and quantity, such that these collectors were not suitable for treating this groundwater. To contextualize the results, a geochemical analysis of the groundwater was conducted, and a consideration of uranium speciation is described. Based on this study, the efficacy of monorhamnolipid-based ion flotation in real world groundwater has been demonstrated with suitable solution conditions and collectors identified.
    • Development of aquaculture protocols and gonadal differentiation of green sunfish (Lepomis cyanellus)

      Teal, Chad N.; Schill, Daniel J.; Fogelson, Susan B.; Roberts, Colby M.; Fitzsimmons, Kevin; Bonar, Scott A.; Arizona Cooperative Fish and Wildlife Research Unit, School of Natural Resources and the Environment, University of Arizona; University of Arizona, School of Natural Resources and the Environment (Elsevier BV, 2022-01)
      We provide detailed rearing methods and describe green sunfish (Lepomis cyanellus) gonadal development and histological differentiation for both sexes. Developing in-depth aquaculture protocols and describing the gonadal differentiation of green sunfish could facilitate strategies to control nuisance populations, enhance stocking programs, and provide information for this species' use in bioassay trials or toxicology studies. Our methods resulted in consistent year-round production of green sunfish and allowed us to identify the timing of their gonadal differentiation through histological assessment. Our spawning methods provided year-round volitional spawns from green sunfish broodstock. Our rearing methods involved weaning larval green sunfish off live nauplii and onto only artificial diets by 37 days post-hatch (dph). Most of the offspring generation reached sexual maturity by 213 dph. Green sunfish are gonochoristic, with testes and ovaries differentiating directly from undifferentiated gonads. Ovaries begin to differentiate by 39 dph and testes begin to differentiate by 69 dph. This information can provide biologists consistent means to produce this Centrachid and understand their gonadal development.
    • Tracking the desert's edge with a Pleistocene relict

      Wilder, Benjamin T.; Becker, Amanda T.; Munguia-Vega, Adrian; Culver, Melanie; Desert Laboratory on Tumamoc Hill, University of Arizona; Department of Ecology and Evolutionary Biology, University of Arizona; School of Natural Resources and the Environment, University of Arizona (Elsevier BV, 2022-01)
      In addition to the Sky Islands of the southwestern U.S. and northwestern Mexico, a series of 900–1200 m desert peaks surrounded by arid lowlands support temperate affiliated species at their summits. The presence of disjunct long-lived plant taxa on under-explored desert mountains, especially Isla Tiburón at 29° latitude in the Gulf of California, suggests a more southerly extent of Ice Age woodlands than previously understood. The phylogeography of the desert edge species Canotia holacantha (Celastraceae) was investigated to test the hypothesis that insular desert peak populations represent remnants of Pleistocene woodlands rather than recent dispersal events. Sequences of four chloroplast DNA regions totaling 2032 bp were amplified from 74 individuals of 14 populations across the entire range of C. holacantha as well as nine individuals that represented the other two species in its clade (C. wendtii and Acanthothamnus aphyllus) and two outgroups. Results suggest that a Canotia common ancestor occurred on the landscape, which underwent a population contraction ca. 15 kya. The Isla Tiburón C. holacantha population and the Chihuahuan Desert microendemic C. wendtii have the greatest genetic differentiation, are sister to one another, and basal to all other Canotia populations. Three haplotypes within C. holacantha were recovered, which correspond to regional geography and thus identified as the Arizona, Sonora, and Tiburón haplotypes, within which Acanthothamnus aphyllus is nested rather than as a sister genus. These results indicate a once broad distribution of Canotia/Acanthothamnus when the current peripheral desert ecotone habitat was more widespread during the Pleistocene, now present in relict populations on the fringes of the southern desert, in the Chihuahuan Desert, with scattered populations on desert peaks, and a common or abundant distribution at the northern boundary of the Sonoran Desert. These results suggest Canotia has tracked the shift of the desert's edge both in latitude and elevation since the end of the last Ice Age.
    • Surrogate approximation of the Grad–Shafranov free boundary problem via stochastic collocation on sparse grids

      Elman, Howard C.; Liang, Jiaxing; Sánchez-Vizuet, Tonatiuh; Department of Mathematics, The University of Arizona (Elsevier BV, 2022-01)
      In magnetic confinement fusion devices, the equilibrium configuration of a plasma is determined by the balance between the hydrostatic pressure in the fluid and the magnetic forces generated by an array of external coils and the plasma itself. The location of the plasma is not known a priori and must be obtained as the solution to a free boundary problem. The partial differential equation that determines the behavior of the combined magnetic field depends on a set of physical parameters (location of the coils, intensity of the electric currents going through them, magnetic permeability, etc.) that are subject to uncertainty and variability. The confinement region is in turn a function of these stochastic parameters as well. In this work, we consider variations on the current intensities running through the external coils as the dominant source of uncertainty. This leads to a parameter space of dimension equal to the number of coils in the reactor. With the aid of a surrogate function built on a sparse grid in parameter space, a Monte Carlo strategy is used to explore the effect that stochasticity in the parameters has on important features of the plasma boundary such as the location of the x-point, the strike points, and shaping attributes such as triangularity and elongation. The use of the surrogate function reduces the time required for the Monte Carlo simulations by factors that range between 7 and over 30.
    • Quantification of intracellular HNO delivery with capillary zone electrophoresis

      Amarakoon, Thilini N.; Ke, Neng; Aspinwall, Craig A.; Miranda, Katrina M.; Department of Chemistry and Biochemistry, University of Arizona; BIO5 Institute, University of Arizona; Department of Biomedical Engineering, University of Arizona (Elsevier BV, 2022-01)
      Redox signaling, wherein reactive and diffusible small molecules are channeled into specific messenger functions, is a critical component of signal transduction. A central principle of redox signaling is that the redox modulators are produced in a highly controlled fashion to specifically modify biotargets. Thiols serve as primary mediators of redox signaling as a function of the rich variety of adducts, which allows initiation of distinct cellular effects. Coupling the inherent reactivity of thiols with highly sensitive and selective chemical analysis protocols can facilitate identification of redox signaling agents, both in solution and in cultured cells. Here, we describe use of capillary zone electrophoresis to both identify and quantify sulfinamides, which are specific markers of the reaction of thiols with nitroxyl (HNO), a putative biologically relevant reactive nitrogen species.