• Arid Ecosystem Vegetation Canopy-Gap Dichotomy: Influence on Soil Microbial Composition and Nutrient Cycling Functional Potential

      Kushwaha, Priyanka; Neilson, Julia W.; Barberán, Albert; Chen, Yongjian; Fontana, Catherine G.; Butterfield, Bradley J.; Maier, Raina M.; Department of Environmental Science, University of Arizona (American Society for Microbiology, 2021-12-11)
      Increasing temperatures and drought in desert ecosystems are predicted to cause decreased vegetation density combined with barren ground expansion. It remains unclear how nutrient availability, microbial diversity, and the associated functional capacity vary between the vegetated canopy and gap soils. The specific aim of this study was to characterize canopy versus gap microsite effect on soil microbial diversity, the capacity of gap soils to serve as a canopy soil microbial reservoir, nitrogen (N)-mineralization genetic potential (ureC gene abundance) and urease enzyme activity, and microbial-nutrient pool associations in four arid-hyperarid geolocations of the western Sonoran Desert, Arizona, United States. Microsite combined with geolocation explained 57% and 45.8% of the observed variation in bacterial/archaeal and fungal community composition, respectively. A core microbiome of amplicon sequence variants was shared between the canopy and gap soil communities; however, canopy soils included abundant taxa that were not present in associated gap communities, thereby suggesting that these taxa cannot be sourced from the associated gap soils. Linear mixed-effects models showed that canopy soils have significantly higher microbial richness, nutrient content, and organic N-mineralization genetic and functional capacity. Furthermore, ureC gene abundance was detected in all samples, suggesting that ureC is a relevant indicator of N mineralization in deserts. Additionally, novel phylogenetic associations were observed for ureC, with the majority belonging to Actinobacteria and uncharacterized bacteria. Thus, key N-mineralization functional capacity is associated with a dominant desert phylum. Overall, these results suggest that lower microbial diversity and functional capacity in gap soils may impact ecosystem sustainability as aridity drives openspace expansion in deserts.
    • Square-shaped sensor clusters for acoustic source localization in anisotropic plates by wave front shape-based approach

      Sen, Novonil; Gawroński, Mateusz; Packo, Pawel; Uhl, Tadeusz; Kundu, Tribikram; Department of Aerospace and Mechanical Engineering, University of Arizona; Department of Civil and Architectural Engineering and Mechanics, University of Arizona (Elsevier BV, 2021-05)
      Various techniques have emerged in the past few years for localizing the acoustic source in an anisotropic plate. The wave front shape-based approach, one of the recent additions to this field of research, has the advantage of circumventing the unrealistic assumption of a straight line wave propagation path through an anisotropic medium. In their most recent versions, the two major wave front shape-based techniques (i.e., the ellipse- and the parametric curve-based techniques) are applicable to the situations with an unknown orientation of the axes of symmetry of an anisotropic plate. However, this approach still relies on estimating the angle of wave-incidence at a given location of the plate via a single L-shaped sensor cluster. The incidence angle so obtained may deviate significantly from the true angle of wave arrival. To improve the estimation accuracy of the incidence angle, in the present study a square-shaped cluster composed of four densely-spaced sensors forming the four vertices of a square is proposed to be installed at the location of interest. Essentially, a square-shaped sensor cluster contains four L-shaped clusters oriented in different directions. A formulation to estimate the angle of incidence from the signal data acquired by a squared-shaped cluster is presented. The wave front shape-based approach can then be applied to estimate the acoustic source location. A numerical study is conducted to illustrate the proposed methodology. Performance comparisons between square- and L-shaped clusters reveal that in general the square-shaped clusters lead to more accurate source location estimates than the L-shaped clusters. © 2020 Elsevier Ltd
    • Unanticipated events, perceptions, and household labor allocation in Zimbabwe

      Josephson, Anna; Shively, Gerald E.; University of Arizona (Elsevier BV, 2021-05)
      This paper investigates labor allocation as a strategy for coping with unanticipated events. We evaluate household responses to unforeseen death and rainfall shocks in Zimbabwe, during a period in which many households were already stressed due to the country's long-term economic crisis. In this context, shocks compound existing stresses. Different types of shocks disparately affect household labor allocation. Household perceptions about the shocks experienced also shift labor use. Perceived rainfall shocks positively affect the share of labor allocated to migration-related activities and negatively affect the share of labor allocated to non-participation. © 2020 Elsevier Ltd
    • Deuterium as a quantitative tracer of enhanced microbial methane production

      Ashley, Kilian; Davis, Katherine J.; Martini, Anna; Vinson, David S.; Gerlach, Robin; Fields, Matthew W.; McIntosh, Jennifer; Department of Hydrology and Atmospheric Sciences, University of Arizona (Elsevier BV, 2021-04)
      Microbial production of natural gas in subsurface organic-rich reservoirs (e.g., coal, shale, oil) can be enhanced by the introduction of amendments (e.g., algal extracts from biofuel production) to stimulate microbial communities to generate “new” methane resources on human timescales, potentially providing a lower carbon energy source. This study tests deuterated water as a tracer to quantify the amount of “new” methane generated and the effectiveness of Microbial Enhancement of Coalbed Methane (MECoM) approaches, as methanogens incorporate hydrogen from formation waters into methane during methanogenesis. Microorganisms (including methanogens), formation water, and coal obtained from the Powder River Basin were used to establish batch reactor stimulation experiments, using algal extracts, in which incremental amounts of deuterated water were added. The greatest amount of methane was produced in the amended coal-associated experiments and there was a consistent uptake of D into microbial methane. The shorter duration (36 days) coal amended experiment had a lower slope (m = 0.31) of δD-CH4 vs. δD-H2O and a similar offset between δD-H2O and δD-CH4 (371.2‰) compared to the longer duration (m = 0.44; 114 days; 358.8‰ offset) experiment, both consistent with the stimulation of primarily acetoclastic methanogenesis. The success of our proof-of-concept laboratory experiments confirms that deuterated water can be used as a quantitative tracer of stimulated coal-associated methanogenic activity. We also provide an example of how it can be applied in field-scale MECoM projects. In addition, deuterated water may serve as a useful tracer for other natural or enhanced subsurface microbial activities, such as microbial enhanced oil recovery or bioremediation of organic contaminants. © 2020 Elsevier Ltd
    • FEAST of biosensors: Food, environmental and agricultural sensing technologies (FEAST) in North America

      McLamore, Eric S.; Alocilja, Evangelyn; Gomes, Carmen; Gunasekaran, Sundaram; Jenkins, Daniel; Datta, Shoumen P.A.; Li, Yanbin; Mao, Yu (Jessie); Nugen, Sam R.; Reyes-De-Corcuera, José I.; et al. (Elsevier BV, 2021-04)
      We review the challenges and opportunities for biosensor research in North America aimed to accelerate translational research. We call for platform approaches based on: i) tools that can support interoperability between food, environment and agriculture, ii) open-source tools for analytics, iii) algorithms used for data and information arbitrage, and iv) use-inspired sensor design. We summarize select mobile devices and phone-based biosensors that couple analytical systems with biosensors for improving decision support. Over 100 biosensors developed by labs in North America were analyzed, including lab-based and portable devices. The results of this literature review show that nearly one quarter of the manuscripts focused on fundamental platform development or material characterization. Among the biosensors analyzed for food (post-harvest) or environmental applications, most devices were based on optical transduction (whether a lab assay or portable device). Most biosensors for agricultural applications were based on electrochemical transduction and few utilized a mobile platform. Presently, the FEAST of biosensors has produced a wealth of opportunity but faces a famine of actionable information without a platform for analytics. © 2021 Elsevier B.V.
    • An elastoplastic solution to undrained expansion of a cylindrical cavity in SANICLAY under plane stress condition

      Li, Lin; Chen, Haohua; Li, Jingpei; Sun, De'an; Department of Civil and Architectural Engineering and Mechanics, The University of Arizona (Elsevier BV, 2021-04)
      Although cylindrical cavity expansion under plane stress condition is commonly encountered in geotechnical problems, most currently available solutions have been developed for cavity expansion under plane strain condition. This paper develops a novel elastoplastic solution for undrained expansion of a cylindrical cavity in SANICLAY under plane stress condition. The SANICLAY model, which could well represent the mechanical behaviour of the anisotropic soil and overconsolidated soil, is employed in the present solution to model the responses of the soil around the expanded cavity. The problem is formulated as a system of first-order differential equations with the unknown variables as the functions of an auxiliary coordinate, which are solved as an initial value problem. The expansion responses under plane stress condition are comprehensively compared with those under plane stress condition to highlight the unique expansion responses under plane stress condition. The results show that the present solution could well reflect the unique expansion responses under plane stress condition, which are totally different from those under plane strain condition. It is expected the proposed solution could provide a reasonable approach to interpret the pressuremeter test and model pile installation effects near the surface of the natural anisotropic clays.
    • Trisomy 21 impairs PGE2 production in dermal fibroblasts

      Marentette, John O.; Anderson, Colin C.; Prutton, Kendra M.; Jennings, Erin Q.; Rauniyar, Abhishek K.; Galligan, James J.; Roede, James R.; Skaggs School of Pharmacy, University of Arizona (Elsevier BV, 2021-04)
      The triplication of human chromosome 21 results in Down syndrome (DS), the most common genetic form of intellectual disability. This aneuploid condition also results in an enhanced risk of a spectrum of comorbid conditions, such as leukemia, early onset Alzheimer's disease, and diabetes. Individuals with DS also display an increased incidence of wound healing complications and resistance to solid tumor development. Due to this unique phenotype and the involvement of eicosanoids in key comorbidities like poor healing and tumor development, we hypothesized that cells from DS individuals would display altered eicosanoid production. Using age- and sex-matched dermal fibroblasts we interrogated this hypothesis. Briefly, assessment of over 90 metabolites derived from cyclooxygenase (COX), lipoxygenase (LOX), and cytochrome p450 systems revealed a possible deficiency in the COX system. Basal gene expression and Western blotting experiments showed significantly decreased gene expression of COX1 and 2, and COX2 protein abundance in DS fibroblasts compared to euploid controls. Further, using two different stressors, scratch wound or LPS, we found that DS fibroblasts could not upregulate COX2 abundance and prostaglandin E2 production. Together, these findings show that dermal fibroblasts from DS individuals have a deficient COX2 response, which may contribute to wound healing complications and tumor resistance in DS. © 2020 Elsevier Inc.
    • Undergraduate data science degrees emphasize computer science and statistics but fall short in ethics training and domain-specific context

      Oliver, Jeffrey C.; McNeil, Torbet; Office of Digital Innovation & Stewardship, University Libraries, University of Arizona; Department of Educational Policy Studies and Practice, University of Arizona (PeerJ, 2021-03-25)
      The interdisciplinary field of data science, which applies techniques from computer science and statistics to address questions across domains, has enjoyed recent considerable growth and interest. This emergence also extends to undergraduate education, whereby a growing number of institutions now offer degree programs in data science. However, there is considerable variation in what the field actually entails and, by extension, differences in how undergraduate programs prepare students for data-intensive careers. We used two seminal frameworks for data science education to evaluate undergraduate data science programs at a subset of 4-year institutions in the United States; developing and applying a rubric, we assessed how well each program met the guidelines of each of the frameworks. Most programs scored high in statistics and computer science and low in domain-specific education, ethics, and areas of communication. Moreover, the academic unit administering the degree program significantly influenced the course-load distribution of computer science and statistics/mathematics courses. We conclude that current data science undergraduate programs provide solid grounding in computational and statistical approaches, yet may not deliver sufficient context in terms of domain knowledge and ethical considerations necessary for appropriate data science applications. Additional refinement of the expectations for undergraduate data science education is warranted.
    • Linear and Nonlinear Ultrasonic Techniques for Monitoring Stress-Induced Damages in Concrete

      Castellano, Anna; Fraddosio, Aguinaldo; Piccioni, Mario Daniele; Kundu, Tribikram; Department of Materials Science and Engineering, University of Arizona; Department of Civil and Architectural Engineering and Mechanics, University of Arizona; Department of Aerospace and Mechanical Engineering, University of Arizona (ASME International, 2021-03-24)
      When stress in concrete exceeds certain threshold value, microcracks are nucleated, these microcracks can propagate and coalesce forming macrocracks, resulting in the gradual decay of the mechanical properties of concrete and eventual failure of the concrete structures. For safety concerns, one needs to develop suitable nondestructive testing methods capable of detecting past overloads of concrete structures during its service life. In this work, the stress-induced damage in concrete is monitored using ultrasonic techniques, exploiting the coupling between the stress level experienced by concrete and its wave propagation parameters. Cyclic compression tests with increasing maximum load level have been performed on specimens made of concrete with coarse-grained (CG) aggregates. Experimental results have been analyzed by two different ultrasonic methods—the linear and the nonlinear ultrasonic techniques. In linear ultrasonic technique, the stress level experienced by the specimens is related to the variations in signal amplitude and velocity of ultrasonic waves. In nonlinear ultrasonic method, the sideband peak count (SPC) technique is used for revealing the stress-induced damage corresponding to each load step. In comparison to linear ultrasonic parameters, the nonlinear ultrasonic parameter SPC-I appears to be more sensitive to the variations of the internal material structures during both loading and unloading phases. Moreover, the SPC technique has shown to be capable of identifying both the initial damage due to the evolution and nucleation of microcracks at the microscopic scale, and the subsequent damages induced by high overload, resulting in an irreversible degradation of the mechanical properties.
    • Death by hand sanitizer: syndemic methanol poisoning in the age of COVID-19

      Holzman, Sarah Denise; Larsen, Jaiva; Kaur, Ramandeep; Smelski, Geoffrey; Dudley, Steven; Shirazi, Farshad Mazda; Arizona Poison and Drug Information Center, University of Arizona College of Pharmacy; Department of Emergency Medicine, University of Arizona College of Medicine; Department of Medical Pharmacology, University of Arizona College of Medicine; Department of Pharmacy Practice and Science, University of Arizona College of Pharmacy (Taylor and Francis Ltd., 2021-03-23)
      Background: The advent of COVID-19 increased attention to hand hygiene in prevention of disease transmission. To meet the increased demand for hand sanitizer during the pandemic, the US FDA issued an Emergency Use Authorization allowing new manufacturers and importers to enter the market. Some of the newly introduced hand sanitizer products contained methanol in lieu of ethanol or isopropanol. We describe five patients with fatal methanol poisoning resulting from hand sanitizers improperly containing methanol. Case summary: Comparing a 5-month period from 2019 to the same time frame in 2020, the Arizona Poison and Drug Information Center has seen an increase of 124% in exposures to hand sanitizer. Of these cases, 28% involved methanol-contaminated hand sanitizer. Five of these patients died from methanol poisoning. All five cases had similar clinical features with severe high anion gap metabolic acidosis and, in four patients, elevated osmolal gap. Methanol concentrations were consistently very elevated, but these results were not available before the patients succumbed. Four of the patients received fomepizole and adjunctive care. Two patients received emergency extracorporeal therapy. All five died despite maximal treatment efforts. Conclusion: During the pandemic in 2020, there was a proliferation of alcohol-based hand sanitizers which contained methanol. Exposure to these products, which failed to meet regulatory standards, led to increased harm and death. Challenges to treatment of methanol poisoning, especially in rural areas, include lack of access to timely laboratory measurement of methanol concentrations and lack of available emergency hemodialysis without transfer of the patient. © 2021 Informa UK Limited, trading as Taylor & Francis Group.
    • Time-Space Distanciation as a Decolonizing Framework for Psychology

      Schmitt, Harrison J.; Young, Isaac F.; Keefer, Lucas A.; Palitsky, Roman; Stewart, Sheridan A.; Goad, Alexis N.; Sullivan, Daniel; University of Arizona (SAGE Publications Ltd, 2021-03-22)
      Coloniality describes the way in which racialized conceptions of being, personhood, and morality inherent in colonial regimes are maintained long after the formal end of colonial enterprises. Central to coloniality has been the material and psychological colonization of space and time, largely by Western and industrialized nations. We propose the importance of understanding the coloniality of time and space through a historically grounded framework called time-space distanciation (TSD). This framework posits that via the global spread of capitalism through colonization, psychological understandings of time and space have been separated from one another, such that they are now normatively treated as distinct entities, each with their own abstract and quantifiable value. We discuss the construct and its centrality to coloniality, as well as the ways in which contemporary psychology has been complicit in proliferating the coloniality of psychologies of time and space. Finally, we discuss ways to employ the decolonial strategies of denaturalization, indigenization, and accompaniment in the context of future research on the psychology of time and space. TSD contributes to decolonial efforts by combatting the reification of hegemonic psychological constructs, showing how these constructs arise as a function of historical changes in understanding, experience, and use of time and space. © 2021 The Author(s).
    • Nonprofit board turnover and financial performance: Examining optimal board turnover rate in United Way organizations

      An, Seung‐Ho; School of Government and Public Policy, University of Arizona (Jossey-Bass Inc., Publishers, 2021-03-22)
      This article examines the effects of board turnover on nonprofit financial performance: resource acquisition and utilization. Governing board members play key roles in connecting organizations with external environments and ensuring that executives properly manage the organizations to achieve organizational missions. They also help in effectively attracting and appropriately utilizing financial resources. Given the importance of governing board members, any turnover occurring in the board should affect nonprofit financial performance. Using insights from organizational theories, we argue that the relationship between board turnover and the ability of UW organizations to acquire and utilize funds is nonlinear (first positive and then negative). We find general support for the hypothesis, which yields implications for both research and practice of board governance and human resources management in the nonprofit sector. © 2021 Wiley Periodicals LLC
    • Student mobility choices in transnational education: impact of macro-, meso- and micro-level factors

      Li, Xiaojie; Haupt, John; Lee, Jenny; Center for the Study of Higher Education, University of Arizona (Routledge, 2021-03-22)
      This study investigates the student mobility choices at different stages in transnational education (TNE) and how their choices are shaped by varying level contexts. Combining survey and interview data collected at a US–China TNE programme, the authors found that majority of students did not intend to be mobile during the programme. Rather, they planned to pursue graduate degrees abroad. Further, the majority of students intended to work in China after the completion of their studies. Student mobility choices into, during and after transnational education, were heavily influenced by the macro-level (e.g., labour market, university admission policies) and meso-level (e.g., programme structures) contexts. © 2021 Association for Tertiary Education Management and the LH Martin Institute for Tertiary Education Leadership and Management.
    • Justice, Reciprocity, and the Boundaries of State Authority

      Motchoulski, Alexander; Philosophy, University of Arizona (Blackwell Publishing Ltd, 2021-03-21)
    • Reconstructing Seasonal and Baseline Nitrogen Isotope Ratios in Riverine Particulate Matter Using Freshwater Mussel Shells

      Kukolich, Stephanie; Dettman, David; Department of Geosciences, University of Arizona (American Geophysical Union (AGU), 2021-03-19)
      We present a timeline of the carbon, nitrogen, and oxygen stable isotope compositions of 10 unionid mussel shells across three species–Threeridge (Amblema plicata), Ebonyshell (Reginaia ebenus), and Pimpleback (Cyclonaias pustulosa)—collected live in 2011 from the Tennessee River near Paducah, Kentucky, USA. Inorganic aragonite δ18O profiles were compared to a predicted shell δ18O time series that was based on water temperature and isotopic composition. Shell growth was assumed to stop below ∼12°C. Profiles of inorganic δ18O and δ13C were then used to establish relationships between shell growth and calendar dates. Because shell growth is faster during warmer months and therefore easy to sample, assignment of calendar years to individual growth increments was validated using the interannual changes in the predicted minimum δ18O value of summer shell. Mussel shell periostracum and carbonate‐bound organic matter (CBOM) samples were then assigned calendar dates based on their location along shell growth axes and compared to measurements of δ13C and δ15N of suspended particulate organic matter (SPOM)–the mussels' food source–during shell growth (1997–2006). Mussel shell periostracum and CBOM faithfully recorded seasonal variability in δ15N and δ13C values of SPOM, after accounting for the time difference between SPOM consumption and deposition of shell organics due to the gradual turnover of mantle tissue. This demonstrates that unionid shell geochemistry could be used to document changes in riverine environment, runoff, and nutrient cycles across a spectrum of time scales, from historical to archeological to Quaternary.
    • Should We Use Expired Drugs When Necessary?

      Iserson, Kenneth V.; Department of Emergency Medicine, The University of Arizona (Elsevier Inc., 2021-03-19)
      Background: Medication shortages commonly occur in resource-poor settings. The relatively short expiry dates on many medications exacerbate these shortages, often requiring clinicians to choose between providing needed medications to the patient and violating rules governing drug dispensing. Case Report: A patient presented to an emergency department in a resource-poor setting with an acute anterior myocardial infarction. Standard of care required using thrombolytics due to the unavailability of percutaneous coronary intervention. The only available thrombolytic, streptokinase, was 2 weeks past its labeled expiration date. The physicians faced the ethical dilemma of violating regulations and using the medication vs. failing to provide the patient with the best available therapy. Discussion: The physicians in this case needed to weigh their obligation to improve the patient's health against the professional danger to themselves, their colleagues, and their institution for violating a health care regulation. The information they needed to make this decision and to provide the patient with factual informed consent requires an understanding of the myths, regulations, and science surrounding drug expiry dates. Two myths about medications pervade both the professional and lay communities—that they are uniformly effective and that medications taken past their expiry dates may be ineffective or even harmful. Scientific studies have demonstrated that both are false. Conclusions: Ethically, physicians have a duty to place their patient's welfare above their own self-interest. In a time of increasing medication shortages around the globe, clinicians need to push rule makers to synchronize drug expiry dates with scientific findings. © 2021 Elsevier Inc.
    • Coronary artery spasm in a 15-year-old male in diabetic ketoacidosis

      Strah, Danielle; Seckeler, Michael; Mendelson, Jenny; University of Arizona, Department of Pediatrics (Cardiology); Department of Pediatrics (Critical Care and Emergency Medicine), University of Arizona (Cambridge University Press, 2021-03-15)
      Coronary artery disease and myocardial infarction are known complications of long-standing diabetes mellitus in adults, but coronary artery spasm is far more rare and has not been reported in children. We present a 15-year-old male in diabetic ketoacidosis who developed diffuse ST segment elevations and elevated troponin with normal coronary arteries on coronary angiography and no signs of pericarditis that was due to coronary artery spasm. © The Author(s), 2021. Published by Cambridge University Press.
    • Integration of metabolomics and transcriptomics reveals convergent pathways driving radiation-induced salivary gland dysfunction

      Meeks, Lauren; De Oliveira Pessoa, Diogo; Martinez, Jessica A; Limesand, Kirsten H; Padi, Megha; Department of Nutritional Sciences, University of Arizona; Bioinformatics Shared Resource, Arizona Cancer Center, University of Arizona; University of Arizona Cancer Center; Department of Molecular and Cellular Biology, University of Arizona (American Physiological Society, 2021-03-15)
      Radiation therapy for head and neck cancer causes damage to the surrounding salivary glands, resulting in salivary gland hypofunction and xerostomia. Current treatments do not provide lasting restoration of salivary gland function following radiation; therefore, a new mechanistic understanding of the radiation-induced damage response is necessary for identifying therapeutic targets. The purpose of the present study was to investigate the metabolic phenotype of radiation-induced damage in parotid salivary glands by integrating transcriptomic and metabolomic data. Integrated data were then analyzed to identify significant gene-metabolite interactions. Mice received a single 5 Gy dose of targeted head and neck radiation. Parotid tissue samples were collected 5 days following treatment for RNA sequencing and metabolomics analysis. Altered metabolites and transcripts significantly converged on a specific region in the metabolic reaction network. Both integrative pathway enrichment using rank-based statistics and network analysis highlighted significantly coordinated changes in glutathione metabolism, energy metabolism (TCA cycle and thermogenesis), peroxisomal lipid metabolism, and bile acid production with radiation. Integrated changes observed in energy metabolism suggest that radiation induces a mitochondrial dysfunction phenotype. These findings validated previous pathways involved in the radiation-damage response, such as altered energy metabolism, and identified robust signatures in salivary glands, such as reduced glutathione metabolism, that may be driving salivary gland dysfunction.
    • Effect of bromhexine in hospitalized patients with COVID-19

      Tolouian, Ramin; Mulla, Zuber D; Jamaati, Hamidreza; Babamahmoodi, Abdolreza; Marjani, Majid; Eskandari, Raha; Dastan, Farzaneh; Renal Section, Southern Arizona VA Health Care System, University of Arizona (BMJ Publishing Group, 2021-03-15)
      Background: Bromhexine is a potent inhibitor of transmembrane serine protease 2 and appears to have an antiviral effect in controlling influenza and parainfluenza infection; however, its efficacy in COVID-19 is controversial. Methods: A group of hospitalized patients with confirmed COVID-19 pneumonia were randomized using 1:1 allocation to either standard treatment lopinavir/ritonavir and interferon beta-1a or bromhexine 8 mg four times a day in addition to standard therapy. The primary outcome was clinical improvement within 28 days, and the secondary outcome measures were time to hospital discharge, all-cause mortality, duration of mechanical ventilation, the temporal trend in 2019-nCoV reverse transcription-polymerase chain reaction positivity and the frequency of adverse drug events within 28 days from the start of medication. Results: A total of 111 patients were enrolled in this randomized clinical trial and data from 100 patients (48 patients in the treatment arm and 52 patients in the control arm) were analyzed. There was no significant difference in the primary outcome of this study, which was clinical improvement. There was no significant difference in the average time to hospital discharge between the two arms. There were also no differences observed in the mean intensive care unit stay, frequency of intermittent mandatory ventilation, duration of supplemental oxygenation or risk of death by day 28 noted between the two arms. Conclusion: Bromhexine is not an effective treatment for hospitalized patients with COVID-19. The potential prevention benefits of bromhexine in asymptomatic postexposure or with mild infection managed in the community remain to be determined.
    • Investigation of frequency-dependent attenuation coefficients for multiple solids using a reliable pulse-echo ultrasonic measurement technique

      Zhang, Guangdong; Li, Xiongbing; Zhang, Shuzeng; Kundu, Tribikram; Department of Civil & Architectural Engineering & Mechanics, University of Arizona (Elsevier B.V., 2021-03-14)
      A well-established narrowband pulse-echo technique is employed and improved further to investigate the frequency-dependent ultrasonic wave attenuation in various solids. During attenuation coefficient measurement, the diffraction correction is introduced to minimize wave beam-spreading loss, and frequency domain signals are used to minimize both the effects of downward shift of frequency and the error in determining the amplitude of time-domain signals. The frequency-dependent attenuation curves for 19 frequently-used solid materials are obtained using this method in the frequency range 1–25 MHz. It is observed from the measurement results of these materials that the attenuation can vary linearly or nonlinearly with the signal frequency, and the potential impact factors of the attenuation-frequency relationship are discussed. The experimental results presented in this paper is expected to provide a good reference for researchers interested in developing and using frequency-dependent attenuation coefficients of materials that are currently missing in the literature. © 2021 Elsevier Ltd