ABOUT THIS COLLECTION

This open access archive contains publications from University of Arizona faculty, researchers and staff, primarily open-access versions of formally published journal articles. The collection includes published articles and final accepted manuscripts submitted by UA faculty under the UA Open Access Policy. The collection also includes books, book chapters, book reviews, presentations, data, and other scholarly materials submitters have chosen to make available in the repository.


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Recent Submissions

  • There is little association between prehospital delay, persistent symptoms, and post-discharge healthcare utilization in patients evaluated for acute coronary syndrome

    Rountree, Lauren M.; Mirzaei, Sahereh; Brecht, Mary-Lynn; Rosenfeld, Anne G.; Daya, Mohamud R.; Knight, Elizabeth; Zègre-Hemsey, Jessica K.; Frisch, Stephanie; Dunn, Susan L.; Birchfield, Jesse; et al. (Elsevier BV, 2022-06)
    Aims: Test for an association between prehospital delay for symptoms suggestive of acute coronary syndrome (ACS), persistent symptoms, and healthcare utilization (HCU) 30-days and 6-months post hospital discharge. Background: Delayed treatment for ACS increases patient morbidity and mortality. Prehospital delay is the largest factor in delayed treatment for ACS. Methods: Secondary analysis of data collected from a multi-center prospective study. Included were 722 patients presenting to the Emergency Department (ED) with symptoms that triggered a cardiac evaluation. Symptoms and HCU were measured using the 13-item ACS Symptom Checklist and the Froelicher's Health Services Utilization Questionnaire-Revised instrument. Logistic regression models were used to examine hypothesized associations. Results: For patients with ACS (n = 325), longer prehospital delay was associated with fewer MD/NP visits (OR, 0.986) at 30 days. Longer prehospital delay was associated with higher odds of calling 911 for any reason (OR, 1.015), and calling 911 for chest related symptoms (OR, 1.016) 6 months following discharge. For non-ACS patients (n = 397), longer prehospital delay was associated with higher odds of experiencing chest pressure (OR, 1.009) and chest discomfort (OR, 1.008) at 30 days. At 6 months, longer prehospital delay was associated with higher odds of upper back pain (OR, 1.013), palpitations (OR 1.014), indigestion (OR, 1.010), and calls to the MD/NP for chest symptoms (OR, 1.014). Conclusions: There were few associations between prehospital delay and HCU for patients evaluated for ACS in the ED. Associations between prolonged delay and persistent symptoms may lead to increased HCU for those without ACS.
  • Chronology of the Golden Horde in Kazakhstan: 14C Dating of Jochi Khan Mausoleum

    Panyushkina, Irina P; Usmanova, Emma R; Uskenbay, Kanat Z; Kozha, Mukhtar B; Dzhumabekov, Dzhambul A; Akhatov, Gaziz A; Jull, A J Timothy; Laboratory of Tree-Ring Research, University of Arizona; Department of Geosciences, University of Arizona; Department of Physics, University of Arizona (Cambridge University Press (CUP), 2022-04-27)
    We present accelerator mass spectrometry radiocarbon (AMS 14C) dating results of the "Jochi Khan Mausoleum"- the proposed burial place of the oldest son of Gengghis Khan in Ulytau, Kazakhstan. The Ulytau region retains 34 burial complexes of Islamic tradition associated with the Golden Horde history (1221-1438 CE). However, there is no calendar-dated chronology of the medieval mausoleums in this region, which complicates their historical interpretation. Three 14C dates from construction timbers and burial of the Jochi Khan mausoleum are calibrated to 1220-1400 CE interval (95.4% range) with the mid-point at 1245 CE for the coffin, 1330 CE for the entry door, and 1350 CE for a masonry wall. The 14C-calibration suggests that the mausoleum was built about 100 years after the death of Jochi (1225 CE) and renovated at least once in the middle of the 14th century. Apparently, the wood for the coffin was harvested sometime in the interval 1220-1270 CE. The calendar ages of the coffin and the mausoleum are ca. 75 years apart. It is possible that the old coffin was placed into a newly constructed mausoleum. However, there is no historical evidence confirming this important re-burial of Jochi. The dating results challenge the attribution of the mausoleum to Jochi Khan. This study demonstrates that the age of the Islamic mausoleums in Ulytau can be successfully dated with 14C. While requiring further data assembly, this first 14C dataset can form the basis of the calendar chronology of the Golden Horde in Kazakhstan. Historical attribution of the mausoleums must be collaborated with the calendar chronology.
  • Scaling the 14C-Excursion Signal in Multiple Tree-Ring Series with Dynamic Time Warping

    Panyushkina, Irina; Livina, Valerie; Molnár, Mihály; Varga, Tamas; Jull, A J Timothy; Laboratory of Tree-Ring Research, University of Arizona; Department of Geosciences, University of Arizona; Department of Physics, University of Arizona (Cambridge University Press (CUP), 2022-04-22)
    A signal of rapid changes in 14C production is logged in annual series of 14C derived from tree rings, which can be associated with diverse effects of cosmic-ray fluxes, including solar burst and supernova events. These 14C signatures may vary in time and space. The intensity and structure of the 14C signal is multifaced, which complicates understanding of the forcing and attribution of the underlying astrophysical events. It was suggested that "14C in 1052/53 CE and 1054/55 CE signatures at a 4‰-6‰ range over two years could be caused by the Crab Nebula supernova (SN1054) or/and solar perturbation. The temporal incoherence of the signals in published 14C series is investigated with dynamic time warping (DTW), novel approach for matching time-behavioral patterns in multiple 14C datasets. DTW analysis of four 14C signatures from tree rings of California, Finland and England suggests that 14C spikes between 1052 CE and 1055 CE can be caused by a single event. The flickering fingerprint may result from cross-dating inconformity. Cross-checking of tree-ring records from distant locations is impossible sometimes due to large difference in environmental conditions limiting tree growth. The methodology helps to align the signals and can be applied to other 14C datasets.
  • The Suasory Force of Sticky Messages: A Replication and Extension

    Liu, Rain Wuyu; Cheng, Ying; Boster, Franklin J.; Townson, Clint; Department of Communication at the University of Arizona (Informa UK Limited, 2022-04-07)
    Stickiness refers to a message’s persuasive properties: simple, unexpected, concrete, credible, emotional, and stories (SUCCES). A sticky message is expected to be more memorable, and hence persuasive, for a longer duration than a non-sticky message. The present research tested this hypothesis first in a longitudinal experiment addressing the issue of applying sunscreen. Results showed a time × message induction non-additive effect such that the non-sticky message effect decayed more than the sticky message, but its explanation remains elusive. Thus, a second experiment was conducted, and prior results were replicated, with a potential explanation for the effect provided.
  • Classification of EEG signals: An interpretable approach using functional data analysis

    Yi, Yuyan; Billor, Nedret; Liang, Mingli; Cao, Xuan; Ekstrom, Arne; Zheng, Jingyi; Department of Psychology, University of Arizona (Elsevier BV, 2022-07)
    Electroencephalography (EEG) is a noninvasive method to record electrical activity of the brain. The EEG data is continuous flow of voltages, in this paper, we consider them as functional data, and propose a three-stage algorithm based on functional data analysis, with the advantage of interpretability. Specifically, the time and frequency information are extracted by wavelet transform in the first stage. Then, functional testing is utilized to select EEG channels and frequencies that show significant differences for different human behaviors. In the third stage, we propose to use penalized multiple functional logistic regression to interpretably classify human behaviors. With simulation and a scalp EEG data as validation set, we show that the proposed three-stage algorithm provides an interpretable classification of the scalp EEG signals.
  • Relating random matrix map enumeration to a universal symbol calculus for recurrence operators in terms of Bessel–Appell polynomials

    Ercolani, Nicholas M.; Waters, Patrick; Department Of Mathematics, The University Of Arizona (World Scientific Pub Co Pte Ltd, 2022-04-29)
    Maps are polygonal cellular networks on Riemann surfaces. This paper analyzes the construction of closed form general representations for the enumerative generating functions associated to maps of fixed but arbitrary genus. The method of construction developed here involves a novel asymptotic symbol calculus for difference operators based on the relation between spectral asymptotics for Hermitian random matrices and asymptotics of orthogonal polynomials with exponential weights. These closed form expressions have a universal character in the sense that they are independent of the explicit valence distribution of the cellular networks within a broad class. Nevertheless the valence distributions may be recovered from the closed form generating functions by a remarkable unwinding identity in terms of Appell polynomials generated by Bessel functions. Our treatment reveals the generating functions to be solutions of nonlinear conservation laws and their prolongations. This characterization enables one to gain insights that go beyond more traditional methods that are purely combinatorial. Universality results are connected to stability results for characteristic singularities of conservation laws that were studied by Caflisch, Ercolani, Hou and Landis, Multi-valued solutions and branch point singularities for nonlinear hyperbolic or elliptic systems, Commun. Pure Appl. Math. 46 (1993) 453-499, as well as directly related to universality results for random matrix spectra.
  • The IAEA Forensics Program: Results of the AMS 14C Intercomparison Exercise on Contemporary Wines and Coffees

    Quarta, G; Hajdas, I; Molnár, M; Varga, T; Calcagnile, L; D’Elia, M; Molnar, A; Dias, J F; Jull, A J T; Department of Geosciences, University of Arizona (Cambridge University Press (CUP), 2022-04-08)
    In the frame of the IAEA-CRP (Coordinated Research Projects): Enhancing Nuclear Analytical Techniques to Meet the Needs of Forensic Sciences, an intercomparison exercise was organized between three AMS laboratories. Aim of the program is to promote the use of nuclear and accelerator-based techniques in routine forensics practice. In this view, one of the key points is the assessment of the precision and accuracy levels achievable on material of forensic interest. We review the general structure and status of the project, with emphasis on results obtained in the analysis of wines of different grape varieties and grounded coffee beans from different locations such as Brazil, Spain, and Italy. The three laboratories processed the samples according to different chemical protocols and performed the 14C measurements using different systems: MICADAS in Zurich and Debrecen and a HVEE 4130HC 3 MV Tandetron in Lecce. Within the quoted uncertainty, the results showed good reproducibility, indicating that uncertainty level of the order of 0.3% are achieved by AMS on a single sample while multiple sample analyses results in precision down to 0.1-0.2%. The measured 14C concentrations on coffee and wine samples resulted to be consistent with atmospheric 14C levels in the growing years.
  • Rape, sunflower and forest honeys for long-term environmental monitoring: Presence of indicator elements and non-photosynthetic carbon in old Hungarian samples

    Sajtos, Zsófi; Varga, Tamás; Gajdos, Zita; Burik, Petra; Csontos, Máté; Lisztes-Szabó, Zsuzsa; Jull, A.J. Timothy; Molnár, Mihály; Baranyai, Edina; Department of Geosciences, University of Arizona; et al. (Elsevier BV, 2022-02)
    In this paper, we present the time-dependent elemental composition and AMS radiocarbon dating results of 36 rape, sunflower and forest honey samples, collected between 1985 and 2018 in geographically close locations. Based on the elemental information, we conclude that bee products regardless the type provide useful environmental information of the previous decades, such as the decreasing trend of airborne Pb emission can be traced. However, radiocarbon results agree less with the atmospheric bomb peak. Random offsets were observed in the specific radiocarbon activity of the honey samples indicating that rape, sunflower and forest honey samples are not as reliable materials for radiocarbon dating as acacia honeys. The radiocarbon results show that the rape, sunflower and forest honey samples can contain non-photosynthetic carbon, presumably derived from the soil. Thus, the complex application of honey samples for environmental reconstruction requires the species-separated investigation of bee products to reveal their adaptability for assessment approaches.
  • The intertextuality and interdiscursivity of “mirroring” in South Korean cyberfeminist posts

    Yang, Sunyoung; Lee, Kathy; University of Arizona (SAGE Publications, 2022-05-07)
    This study examines the phenomenon of “mirroring” used by Womad, a cyberfeminist community in South Korea. Mirroring involves the reversal of gender to spotlight misogynist practices that might otherwise go unnoticed. To better understand mirroring, we introduce selected posts from Ilbe, a male-dominant online forum, known for denigrating Korean women and then analyze Womad’s posts on similar topics following approaches in critical discourse analysis and feminist post-structuralism. Our analysis examines two main linguistic strategies of mirroring that Womad uses to disrupt gendered ideologies. First, we focus on the use of intertextuality in Womad’s posts through their adoption of Ilbe’s masculine register to combat misogyny by targeting men. Interdiscursivity is another important strategy Womad users deploy to foreground the inequities entrenched in Korea’s long-standing patriarchy. Ultimately, mirroring offers critiques of gender inequity and misogyny through active engagements with everyday linguistic practices online while opening up new possibilities for gender politics.
  • Do mathematicians interpret equations asymmetrically?

    Mirin, Alison; Dawkins, Paul Christian; University of Arizona (Elsevier BV, 2022-06)
    In studies of children's reasoning about equations, a major finding is that many children understand equality to be asymmetric. In this study, we investigate how experts interpret equations in order to determine whether and why they interpret equations asymmetrically. We do so by using a breaching experiment in which we present nine mathematicians with equations that have been purposefully reordered to see if they critique or correct the ordering. We found clear evidence that they apply norms of ordering to critique the texts. We characterize their explanations for why they prefer or expect one order over another by using six rationales that express why experts read equations asymmetrically. We consider the implications for how we characterize sophisticated meanings of the equals sign. Our findings show that mathematicians attend to the coherence of a text, the communicational needs of the reader, and imagined context to determine appropriate equation order.
  • BASH-GN: A new machine learning–derived questionnaire for screening obstructive sleep apnea

    Huo, Jiayan; Quan, Stuart F.; Roveda, Janet; Li, Ao; Biomedical Engineering, The University of Arizona; Asthma and Airway Disease Research Center, College of Medicine, The University of Arizona; Department of Electrical and Computer Engineering, The University of Arizona; BIO5 Institute, The University of Arizona (Springer Science and Business Media LLC, 2022-04-28)
    Purpose: This study aimed to develop a machine learning–based questionnaire (BASH-GN) to classify obstructive sleep apnea (OSA) risk by considering risk factor subtypes. Methods: Participants who met study inclusion criteria were selected from the Sleep Heart Health Study Visit 1 (SHHS 1) database. Other participants from the Wisconsin Sleep Cohort (WSC) served as an independent test dataset. Participants with an apnea hypopnea index (AHI) ≥ 15/h were considered as high risk for OSA. Potential risk factors were ranked using mutual information between each factor and the AHI, and only the top 50% were selected. We classified the subjects into 2 different groups, low and high phenotype groups, according to their risk scores. We then developed the BASH-GN, a machine learning–based questionnaire that consists of two logistic regression classifiers for the 2 different subtypes of OSA risk prediction. Results: We evaluated the BASH-GN on the SHHS 1 test set (n = 1237) and WSC set (n = 1120) and compared its performance with four commonly used OSA screening questionnaires, the Four-Variable, Epworth Sleepiness Scale, Berlin, and STOP-BANG. The model outperformed these questionnaires on both test sets regarding the area under the receiver operating characteristic (AUROC) and the area under the precision-recall curve (AUPRC). The model achieved AUROC (SHHS 1: 0.78, WSC: 0.76) and AUPRC (SHHS 1: 0.72, WSC: 0.74), respectively. The questionnaire is available at https://c2ship.org/bash-gn. Conclusion: Considering OSA subtypes when evaluating OSA risk may improve the accuracy of OSA screening.
  • PhD students as boundary spanning agents: an exploration of student values, goals, and agency in the era of cross-sector permeation

    Mars, Matthew M.; Moravec, Bryan G.; Department of Agricultural Education, Technology and Innovation, University of Arizona; Department of Environmental Science, University of Arizona (Emerald, 2022-05-10)
    Purpose: Market forces and other external pressures have significantly transformed higher education over the past four decades. Research on the influence of cross-sector permeation on doctoral education has primarily focused on preparing and socializing students for academic careers that involve entrepreneurial activity. Conversely, PhD student agency involving cross-sector engagement and the pursuit of individual values and goals in ways that span the boundaries of academia have been overlooked. The purpose of this study is to qualitatively explore how a sample of Doctor of Philosophy (PhD) students in Science, Technology, Mathematics and Engineering (STEM) programs recognized, made sense of and navigated cross-sector permeation relevant to their individual passions and commitments to climate change alleviation. Design/methodology/approach: The authors conducted an embedded case study that qualitatively explored how 16 STEM PhD students recognized, made sense of and navigated cross-sector permeation relevant to their individual values and goals and commitments to climate change alleviation. Data were collected through individual interviews that probed the participants’ engagement and agency in cross-sector permeation. Findings: The authors identified three themes that frame the role of PhD students as boundary spanning agents. The themes involve students placing their values and goals over specific positions and career paths, aligning their values and goals with cross-sector conditions and creating opportunities through cross-sector engagement. Practical implications: Recommendations are provided for fostering and enhancing the agency PhD students have over the pursuit of their individual values and goals and their engagement in boundary spanning activities and strategies. Originality/value: Cross-sector permeation is framed relevant to PhD student agency and boundary spanning. The findings introduce the role of PhD students as boundary spanning agents who intentionally pursue their individual values and goals in ways that extend beyond traditional academic career pathways.
  • Model selection using baryon acoustic oscillations in the final SDSS-IV release

    Melia, F.; López-Corredoira, M.; Department of Physics, University of Arizona; Applied Math Program, University of Arizona; Department of Astronomy, University of Arizona (World Scientific Pub Co Pte Ltd, 2022-04-25)
    The baryon acoustic oscillation (BAO) peak, seen in the cosmic matter distribution at redshifts up to 3.5, reflects the continued expansion of the sonic horizon first identified in temperature anisotropies of the cosmic microwave background. The BAO peak position can now be measured to better than 1% accuracy using galaxies and 1.4-1.6% precision with Ly-α forests and the clustering of quasars. In conjunction with the Alcock-Paczynski (AP) effect, which arises from the changing ratio of angular to spatial/redshift size of (presumed) spherically-symmetric source distributions with distance, the BAO measurement is viewed as one of the most powerful tools to use in assessing the geometry of the Universe. In this paper, we employ five BAO peak measurements from the final release of the Sloan Digital Sky Survey IV, at average redshifts (z) = 0.38, 0.51, 0.70, 1.48 and 2.33, to carry out a direct head-to-head comparison of the standard model, CDM, and one of its principal competitors, known as the Rh = ct universe. For completeness, we complement the AP diagnostic with a volume-averaged distance probe that assumes a constant comoving distance scale rd. Both probes are free of uncertain parameters, such as the Hubble constant, and are therefore ideally suited for this kind of model selection. We find that Rh = ct is favored by these measurements over the standard model based solely on the AP effect, with a likelihood 75% versus 25%, while Planck-CDM is favored over Rh = ct based solely on the volume-averaged distance probe, with a likelihood 80% versus 20%. A joint analysis using both probes produces an inconclusive outcome, yielding comparable likelihoods to both models. We are therefore not able to confirm with this work that the BAO data, on their own, support an accelerating Universe.
  • Evaluating the reliability and validity of a questionnaire used to measure experiences of teamwork among student pharmacists in a quality improvement course

    Arku, Daniel; Almatruk, Ziyad; Warholak, Terri; Axon, David R.; University of Arizona College of Pharmacy (Elsevier BV, 2022-05)
    Introduction: The psychometric properties of instruments used to capture student pharmacists' perspectives of teamwork have not been well assessed. This study measured the reliability and validity of an instrument designed to assess teamwork experiences among student pharmacists in a quality improvement (QI) class at one United States pharmacy school. Methods: The psychometric properties of a previously conducted 17-item questionnaire (response options: “strongly agree,” “agree,” “disagree,” or “strongly disagree”) about second-year student pharmacists' teamworking experiences were assessed. A Rasch rating scale model was used to construct measures of teamwork experience. Principal component analysis (PCA) assessed unidimensionality. Item- and person-fit statistics were assessed. Construct and content validity and reliability were estimated utilizing student and item separation indices (SI) and reliability coefficients (RC). Results: Sixty student pharmacists were included. PCA conveyed a unidimensional construct. Four items with infit and outfit mean-squared values outside the suggested range were removed. Item responses “disagree” and “strongly disagree” were merged to improve scale functionality. The average person measure was 1.74 ± 2.03 logits. Student and item RC were 0.81 (SI = 2.04) and 0.97 (SI = 2.17), respectively. The easiest item endorsed was team's ability to reach consensus, while the most difficult item was interest to do collaborative work again. Mismatch of student experience and item difficulty level on the continuum scale suggested additional items are needed to match student teamwork experience. Conclusion: The instrument demonstrated evidence of reliability and validity to measure student pharmacists' teamwork experience in a QI class, but additional instrument modifications are recommended.
  • Climate refugia for Pinus spp. in topographic and bioclimatic environments of the Madrean sky islands of México and the United States

    Haire, Sandra L.; Villarreal, Miguel L.; Cortés-Montaño, Citlali; Flesch, Aaron D.; Iniguez, José M.; Romo-Leon, Jose Raul; Sanderlin, Jamie S.; School of Natural Resources and the Environment and Desert Laboratory on Tumamoc Hill, University of Arizona (Springer Science and Business Media LLC, 2022-04-01)
    Climate refugia, or places where habitats are expected to remain relatively buffered from regional climate extremes, provide an important focus for science and conservation planning. Within high-priority, multi-jurisdictional landscapes like the Madrean sky islands of the United States and México, efforts to identify and manage climate refugia are hindered by the lack of high-quality and consistent transboundary datasets. To fill these data gaps, we assembled a bi-national field dataset (n = 1416) for five pine species (Pinus spp.) and used generalized boosted regression to model pine habitats in relation to topographic variability as a basis for identifying potential microrefugia at local scales in the context of current species’ distribution patterns. We developed additional models to quantify climatic refugial attributes using coarse scale bioclimatic variables and finer scale seasonal remote sensing indices. Terrain metrics including ruggedness, slope position, and aspect defined microrefugia for pines within elevation ranges preferred by each species. Response to bioclimatic variables indicated that small shifts in climate were important to some species (e.g., P. chihuahuana, P. strobiformis), but others exhibited a broader tolerance (e.g., P. arizonica). Response to seasonal climate was particularly important in modeling microrefugia for species with open canopy structure and where regular fires occur (e.g., P. engelmannii and P. chihuahuana). Hotspots of microrefugia differed among species and were either limited to northern islands or occurred across central or southern latitudes. Mapping and validation of refugia and their ecological functions are necessary steps in developing regional conservation strategies that cross jurisdictional boundaries. A salient application will be incorporation of climate refugia in management of fire to restore and maintain pine ecology. Una versión en español de este artículo está disponible como descarga.
  • Where did the Arizona-Plano Go? Protracted Thinning Via Upper- to Lower-Crustal Processes

    Jepson, G.; Carrapa, B.; George, S.W.M.; Reeher, L.J.; Kapp, P.A.; Davis, G.H.; Thomson, S.N.; Amadori, C.; Clinkscales, C.; Jones, S., I; et al. (John Wiley and Sons Inc, 2022)
    Mesozoic-Cenozoic subduction of the Farallon slab beneath North America generated a regionally extensive orogenic plateau in the southwestern US during the latest Cretaceous, similar to the modern Central Andean Plateau. In Nevada and southern Arizona, estimates from whole-rock geochemistry suggest crustal thicknesses reached ∼60–55 km by the Late Cretaceous. Modern crustal thicknesses are ∼28 km, requiring significant Cenozoic crustal thinning. Here, we compare detailed low-temperature thermochronology from the Catalina metamorphic core complex (MCC) to whole rock Sr/Y crustal thickness estimates across southern Arizona. We identify three periods of cooling. A minor cooling phase occurred prior to ∼40 Ma with limited evidence of denudation and ∼10 km of crustal thinning. Major cooling occurred during detachment faulting and MCC formation at 26–19 Ma, corresponding to ∼8 km of denudation and ∼8 km of crustal thinning. Finally, we document a cooling phase at 17–11 Ma related to Basin and Range extension that corresponds with ∼5 km of denudation and ∼9 km of crustal thinning. During the MCC and Basin and Range extension events, the amount of denudation recorded by low-temperature thermochronology can be explained by corresponding decreases in the crustal thickness. However, the relatively limited exhumation prior to detachment faulting at ∼26 Ma recorded by thermochronology is insufficient to explain the magnitude of crustal thinning (∼10 km) observed in the whole rock crustal thickness record. Therefore, we suggest that crustal thinning of the Arizona-plano was facilitated via ductile mid- to lower-crustal flow, and limited upper-crustal extension at 50–30 Ma prior to detachment faulting and Basin and Range extension. © 2022. American Geophysical Union. All Rights Reserved.
  • Coupling of Tree Growth and Photosynthetic Carbon Uptake Across Six North American Forests

    Teets, A.; Moore, D.J.P.; Alexander, M.R.; Blanken, P.D.; Bohrer, G.; Burns, S.P.; Carbone, M.S.; Ducey, M.J.; Fraver, S.; Gough, C.M.; et al. (John Wiley and Sons Inc, 2022)
    Linking biometric measurements of stand-level biomass growth to tower-based measurements of carbon uptake—gross primary productivity and net ecosystem productivity—has been the focus of numerous ecosystem-level studies aimed to better understand the factors regulating carbon allocation to slow-turnover wood biomass pools. However, few of these studies have investigated the importance of previous year uptake to growth. We tested the relationship between wood biomass increment (WBI) and different temporal periods of carbon uptake from the current and previous years to investigate the potential lagged allocation of fixed carbon to growth among six mature, temperate forests. We found WBI was strongly correlated to carbon uptake across space (i.e., long-term averages at the different sites) but on annual timescales, WBI was much less related to carbon uptake, suggesting a temporal mismatch between C fixation and allocation to biomass. We detected lags in allocation of the previous year's carbon uptake to WBI at three of the six sites. Sites with higher annual WBI had overall stronger correlations to carbon uptake, with the strongest correlations to carbon uptake from the previous year. Only one site had WBI with strong positive relationships to current year uptake and not the previous year. Forests with low rates of WBI demonstrated weak correlations to carbon uptake from the previous year and stronger relationships to current year climate conditions. Our work shows an important, but not universal, role of lagged allocation of the previous year's carbon uptake to growth in temperate forests. © 2022. American Geophysical Union. All Rights Reserved.
  • Energy transfer processes in hyperfluorescent organic light-emitting diodes

    Cho, E.; Hong, M.; Yang, Y.S.; Cho, Y.J.; Coropceanu, V.; Brédas, J.-L.; Department of Chemistry and Biochemistry, The University of Arizona (Royal Society of Chemistry, 2022)
    Hyperfluorescent organic light-emitting diodes (OLEDs) are based on a combination of molecules displaying thermally activated delayed fluorescence (TADF) and of fluorescent emitters embedded into a host matrix; excitons formed on the TADF molecules are expected to transfer to the fluorescent emitters. As a result, device performance strongly depends on the efficiency of the relevant energy transfer processes. Here, we investigate the morphology, excited-state properties, and energy-transfer processes in a ternary TBRb:4CzIPN:mCBP blend by using complementary molecular dynamics simulations and density functional theory calculations. The results indicate that the rate constants for singlet exciton energy transfer from 4CzIPN (TADF) molecules to TBRb fluorescent emitters are about three orders of magnitude larger than both the intersystem crossing (ISC) and radiative decay rate constants of 4CzIPN; thus, the vast majority of the singlet 4CzIPN excitons can efficiently transfer to the emitters. In contrast, the transfer of triplet excitons from 4CzIPN to the emitters is limited due to a fast reverse ISC (RISC) transition. Also, it is found that singlet and triplet energy transfer from mCBP to 4CzIPN and TBRb is very efficient. As a result of quasi resonance between the emissive first excited state and the second triplet state of TBRb, not all triplet excitons that reach TBRb are lost since part of them can convert into singlet excitons via a RISC process. © 2022 The Royal Society of Chemistry
  • Ferrofettelite, [Ag6As2S7][Ag10FeAs2S8], a new sulfosalt from the Glasberg quarry, Odenwald, Germany

    Bindi, L.; Downs, R.T.; Department of Geosciences, University of Arizona (Cambridge University Press, 2022)
    Ferrofettelite, ideally [Ag6As2S7][Ag10FeAs2S8], is a new mineral (IMA No. 2021-094) from the Glasberg quarry, Nieder-Beerbach, Odenwald, south-western Germany. It occurs as anhedral to subhedral flakes and grains up to 80 μm, associated with proustite and xanthoconite, on arsenolite, calcite and prehnite. Ferrofettelite is opaque with a metallic luster and possesses a dark reddish-grey streak. It is brittle with an uneven fracture; the Vickers microhardness (VHN20) is 122 kg/mm2(range 111–131). The calculated density is 5.74 g/cm3(on the basis of the empirical formula). In plane-polarized reflected light, ferrofettelite is greyish white. Between crossed polars it is weakly anisotropic with red internal reflections. Electron-microprobe analyses give the chemical formula Ag16.04(Fe0.55Hg0.40Cu0.02)Σ0.97(As3.94Sb0.03)Σ3.97S15.02 on the basis of total atoms = 36. Ferrofettelite is monoclinic, space group C2, with a = 26.011(2), b = 15.048(1), c = 15.513(1) Å, β = 90.40(1)°, V = 6071.9(7) Å3, and Z = 8. The six strongest Bragg peaks in the X-ray powder diffraction pattern (d[Å], I[%], hkl) are: (3.18, 50, -801), (3.104, 100, 005), (3.004, 60, -802), (2.755, 40, -443), (2.501, 30, -444) and (1.880, 30, 1240). The crystal structure can be described as the alternation of two kinds of layers along the c-axis: layer A with general composition [Ag6As2S7]2-and layer B with a general composition of [Ag10FeAs2S8]2+. In the structure, the Ag atoms adopt various coordinations extending from quasi linear to quasi tetrahedral, the AsS3 groups form pyramids as are typically observed in sulfosalts, and mixed (Fe,Hg) links two sulfur atoms in a linear coordination. Ferrofettelite is the first reported inorganic phase showing a linear coordination for Fe2+. The high-temperature behavior of ferrofettelite was studied up to 410 K and compared to that of fettelite. © 2022 Cambridge University Press. All rights reserved.
  • Tautomers of 6-thiopurine in low-temperature Ar matrices: FTIR spectroscopy analysis and quantum mechanical calculations

    Ivanov, A.Yu.; Stepanian, S.G.; Karachevtsev, V.A.; Adamovicz, L.; Department of Chemistry and Biochemistry, University of Arizona (American Institute of Physics Inc., 2022)
    The structures and vibrational spectra of 6-thiopurine (6TP) molecules in an isolated state were studied by the spectroscopic and computational methods. FTIR spectra of 6TP molecules isolated in low-temperature Ar matrices (at 11 K) were obtained in the infrared range 3800-200 cm-1. The optimized structures of tautomers, model clusters and the population of tautomers were estimated by the DFT, MP2 and CCSD(T) methods. The vibrational spectra were calculated by the DFT/B3LYP method with different basis sets [6-311++G(df,pd), aug-cc-pVDZ, aug-cc-pVTZ] and the MP2/aug-cc-pVDZ/anharmonic method. In the spectral range of 1700-200 cm-1 of the experimental FTIR spectra, five combination modes enhanced by the Fermi resonance were observed. Fermi resonances with the participation of librational modes of domestic molecules were found in the 600-500 cm-1 region. It was revealed that the incorporation of 6TP between the closest packing planes of Ar lattice leads to a significant increase in the frequency of two out-of-plane "butterfly"modes. © 2022 Author(s).

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