Showing papers by "Kent State University published in 2017"

Conservation of resources: A general stress theory applied to burnout.

Abstract: This chapter outlines a general theory of stress termed conservation of resources (COR). It provides an overarching framework to understand the nature of stress as a human phenomenon that is tied to people's experience regardless of the setting or context, be it work, home, hunt, or vacation. COR theory is a basic motivational theory and it is postulated that when this basic motivation is threatened or denied, stress ensues. It may be applied as a theoretical model that explains the etiology of burnout and the processes that are likely to accompany chronic, relatively low-level, work-related stress. COR theory proposes that loss is primary, but let us consider some of the other leading approaches. It suggests that intervention should be based on enhancing resources and eliminating vulnerability to resource loss. A cognitive approach to stress management might act to enhance people's sense of personality hardiness.

Self-Templating Synthesis of Hollow Co3O4 Microtube Arrays for Highly Efficient Water Electrolysis

Abstract: In spite of recent advances in the synthesis of hollow micro/nanostructures, the fabrication of three-dimensional electrodes on the basis of these structures remains a major challenge. Herein, we develop an electrochemical sacrificial-template strategy to fabricate hollow Co3O4 microtube arrays with hierarchical porosity. The resultant unique structures and integrated electrode configurations impart enhanced mass transfer and electron mobility, ensuring high activity and stability in catalyzing oxygen and hydrogen evolution reactions. Impressively, the apparent performance can rival that of state-of-the-art noble-metal and transition-metal electrocatalysts. Furthermore, this bifunctional electrode can be used for highly efficient overall water splitting, even competing with the integrated performance of Pt/C and IrO2/C.

Ultra-thin nanosheet assemblies of graphitic carbon nitride for enhanced photocatalytic CO2 reduction

Abstract: A two-dimensional layered polymeric photocatalyst, graphitic carbon nitride (g-C3N4), is becoming the rising star in the field of solar-to-fuel conversion. However, the performance of commonly prepared g-C3N4 is usually very weak because of the high recombination rate of photogenerated charge carriers and a small amount of surface active sites. Here we demonstrate simultaneous texture modification and surface functionalization of g-C3N4via a stepwise NH3-mediated thermal exfoliation approach. The resulting g-C3N4 photocatalyst possesses a hierarchical structure obtained by the assembly of amine-functionalized ultrathin nanosheets and thus exhibits remarkably enhanced light harvesting, a high redox ability of charge carriers, increased CO2 adsorption and a larger amount of surface active sites, as well as improved charge carrier transfer and separation. Therefore the aforementioned hierarchical g-C3N4 consisting of amine-functionalized ultra-thin nanosheets shows much better performance for photocatalytic CO2 reduction than unmodified conventional g-C3N4 photocatalysts.

Bulk properties of the medium produced in relativistic heavy-ion collisions from the beam energy scan program

Abstract: © 2017 American Physical Society. We present measurements of bulk properties of the matter produced in Au+Au collisions at sNN=7.7,11.5,19.6,27, and 39 GeV using identified hadrons (π±, K±, p, and p) from the STAR experiment in the Beam Energy Scan (BES) Program at the Relativistic Heavy Ion Collider (RHIC). Midrapidity (|y| < 0.1) results for multiplicity densities dN/dy, average transverse momenta (pT), and particle ratios are presented. The chemical and kinetic freeze-out dynamics at these energies are discussed and presented as a function of collision centrality and energy. These results constitute the systematic measurements of bulk properties of matter formed in heavy-ion collisions over a broad range of energy (or baryon chemical potential) at RHIC.

Molecular Scaffolding Strategy with Synergistic Active Centers To Facilitate Electrocatalytic CO2 Reduction to Hydrocarbon/Alcohol

Abstract: A major impediment to the electrocatalytic CO2 reduction reaction (CRR) is the lack of electrocatalysts with both high efficiency and good selectivity toward liquid fuels or other valuable chemicals. Effective strategies for the design of electrocatalysts are yet to be discovered to substitute the conventional trial-and-error approach. This work shows that a combination of density functional theory (DFT) computation and experimental validation of molecular scaffolding to coordinate the metal active centers presents a new molecular-level strategy for the development of electrocatalysts with high CRR selectivity toward hydrocarbon/alcohol. Taking the most widely investigated Cu as a probe, our study reveals that the use of graphitic carbon nitride (g-C3N4) as a molecular scaffold allows for an appropriate modification of the electronic structure of Cu in the resultant Cu–C3N4 complex. As a result, the adsorption behavior of some key reaction intermediates can be optimized on the Cu–C3N4 surface, which great...

Activating cobalt(II) oxide nanorods for efficient electrocatalysis by strain engineering

Abstract: Designing high-performance and cost-effective electrocatalysts toward oxygen evolution and hydrogen evolution reactions in water-alkali electrolyzers is pivotal for large-scale and sustainable hydrogen production. Earth-abundant transition metal oxide-based catalysts are particularly active for oxygen evolution reaction; however, they are generally considered inactive toward hydrogen evolution reaction. Here, we show that strain engineering of the outermost surface of cobalt(II) oxide nanorods can turn them into efficient electrocatalysts for the hydrogen evolution reaction. They are competitive with the best electrocatalysts for this reaction in alkaline media so far. Our theoretical and experimental results demonstrate that the tensile strain strongly couples the atomic, electronic structure properties and the activity of the cobalt(II) oxide surface, which results in the creation of a large quantity of oxygen vacancies that facilitate water dissociation, and fine tunes the electronic structure to weaken hydrogen adsorption toward the optimum region.

Engineering High‐Energy Interfacial Structures for High‐Performance Oxygen‐Involving Electrocatalysis

Abstract: Engineering high-energy interfacial structures for high-performance electrocatalysis is achieved by chemical coupling of active CoO nanoclusters and high-index facet Mn3O4 nano-octahedrons (hi-Mn3O4). A thorough characterization, including synchrotron-based near edge X-ray absorption fine structure, reveals that strong interactions between both components promote the formation of high-energy interfacial Mn-O-Co species and high oxidation state CoO, from which electrons are drawn by MnIII-O present in hi-Mn3O4. The CoO/hi-Mn3O4 demonstrates an excellent catalytic performance over the conventional metal oxide-based electrocatalysts, which is reflected by 1.2 times higher oxygen evolution reaction (OER) activity than that of Ru/C and a comparable oxygen reduction reaction (ORR) activity to that of Pt/C as well as a better stability than that of Ru/C (95 % vs. 81 % retained OER activity) and Pt/C (92 % vs. 78 % retained ORR activity after 10 h running) in alkaline electrolyte.

Na 2 Ti 3 O 7 @N-Doped Carbon Hollow Spheres for Sodium-Ion Batteries with Excellent Rate Performance

Abstract: Uniform Na2 Ti3 O7 hollow spheres assembled from N-doped carbon-coated ultrathin nanosheets are synthesized. A unique multilayer structure of nanosheets is presumed to significantly reduce energy consumption during the diffusion process of sodium ions, while the carbon-coated structure can increase the overall conductivity. The as-prepared sample used as an anode in sodium-ion batteries exhibits the best rate performance ever reported for Na2 Ti3 O7 , delivering more than 60 mAh g-1 after 1000 continuous cycles at the high rate of 50 C, which was achieved due to its unique structure.

A global Fine-Root Ecology Database to address below-ground challenges in plant ecology.

Abstract: Variation and tradeoffs within and among plant traits are increasingly being harnessed by empiricists and modelers to understand and predict ecosystem processes under changing environmental conditions. While fine roots play an important role in ecosystem functioning, fine-root traits are underrepresented in global trait databases. This has hindered efforts to analyze fine-root trait variation and link it with plant function and environmental conditions at a global scale. This Viewpoint addresses the need for a centralized fine-root trait database, and introduces the Fine-Root Ecology Database (FRED, http://roots.ornl.gov) which so far includes > 70 000 observations encompassing a broad range of root traits and also includes associated environmental data. FRED represents a critical step toward improving our understanding of below-ground plant ecology. For example, FRED facilitates the quantification of variation in fine-root traits across root orders, species, biomes, and environmental gradients while also providing a platform for assessments of covariation among root, leaf, and wood traits, the role of fine roots in ecosystem functioning, and the representation of fine roots in terrestrial biosphere models. Continued input of observations into FRED to fill gaps in trait coverage will improve our understanding of changes in fine-root traits across space and time.

Atomically and Electronically Coupled Pt and CoO Hybrid Nanocatalysts for Enhanced Electrocatalytic Performance

Abstract: Atomically and electronically coupled Pt and CoO hybrid nanocatalysts are fabricated for electrocatalytic oxygen reduction reaction. The atomic coupling between the Pt and the CoO endows precise control of the atomic interface between the Pt and the CoO, which directly results in electron donation from the CoO to the Pt, and thus favorable tuning of the electronic structure of the Pt.

Climate, soil and plant functional types as drivers of global fine-root trait variation

Abstract: 1.Ecosystem functioning relies heavily on belowground processes, which are largely regulated by plant fine-roots and their functional traits. However, our knowledge of fine-root trait distribution relies to date on local- and regional-scale studies with limited numbers of species, growth forms and environmental variation. 2.We compiled a worldwide fine-root trait dataset, featuring 1115 species from contrasting climatic areas, phylogeny and growth forms to test a series of hypotheses pertaining to the influence of plant functional types, soil and climate variables, and the degree of manipulation of plant growing conditions on species fine-root trait variation. Most particularly, we tested the competing hypotheses that fine-root traits typical of faster return on investment would be most strongly associated with conditions of limiting versus favourable soil resource availability. We accounted for both data source and species phylogenetic relatedness. 3.We demonstrate that (1) Climate conditions promoting soil fertility relate negatively to fine-root traits favouring fast soil resource acquisition, with a particularly strong positive effect of temperature on fine-root diameter and negative effect on specific root length (SRL), and a negative effect of rainfall on root nitrogen concentration; (2) Soil bulk density strongly influences species fine-root morphology, by favouring thicker, denser fine-roots; (3) Fine-roots from herbaceous species are on average finer and have higher SRL than those of woody species, and N2-fixing capacity positively relates to root nitrogen; (4) Plants growing in pots have higher SRL than those grown in the field. 4.Synthesis. This study reveals both the large variation in fine-root traits encountered globally and the relevance of several key plant functional types and soil and climate variables for explaining a substantial part of this variation. Climate, particularly temperature, and plant functional types were the two strongest predictors of fine-root trait variation. High trait variation occurred at local scales, suggesting that wide-ranging belowground resource economics strategies are viable within most climatic areas and soil conditions.

A worldview of root traits: the influence of ancestry, growth form, climate and mycorrhizal association on the functional trait variation of fine-root tissues in seed plants.

Abstract: Fine-root traits play key roles in ecosystem processes, but the drivers of fine-root trait diversity remain poorly understood. The plant economic spectrum (PES) hypothesis predicts that leaf and root traits evolved in coordination. Mycorrhizal association type, plant growth form and climate may also affect root traits. However, the extent to which these controls are confounded with phylogenetic structuring remains unclear. Here we compiled information about root and leaf traits for > 600 species. Using phylogenetic relatedness, climatic ranges, growth form and mycorrhizal associations, we quantified the importance of these factors in the global distribution of fine-root traits. Phylogenetic structuring accounts for most of the variation for all traits excepting root tissue density, with root diameter and nitrogen concentration showing the strongest phylogenetic signal and specific root length showing intermediate values. Climate was the second most important factor, whereas mycorrhizal type had little effect. Substantial trait coordination occurred between leaves and roots, but the strength varied between growth forms and clades. Our analyses provide evidence that the integration of roots and leaves in the PES requires better accounting of the variation in traits across phylogenetic clades. Inclusion of phylogenetic information provides a powerful framework for predictions of belowground functional traits at global scales.

Large Bulk Photovoltaic Effect and Spontaneous Polarization of Single-Layer Monochalcogenides.

Abstract: We use a first-principles density functional theory approach to calculate the shift current and linear absorption of uniformly illuminated single-layer Ge and Sn monochalcogenides We predict strong absorption in the visible spectrum and a large effective three-dimensional shift current ($\ensuremath{\sim}100\text{ }\text{ }\ensuremath{\mu}\mathrm{A}/{\mathrm{V}}^{2}$), larger than has been previously observed in other polar systems Moreover, we show that the integral of the shift-current tensor is correlated to the large spontaneous effective three-dimensional electric polarization ($\ensuremath{\sim}19\text{ }\text{ }\mathrm{C}/{\mathrm{m}}^{2}$) Our calculations indicate that the shift current will be largest in the visible spectrum, suggesting that these monochalcogenides may be promising for polar optoelectronic devices A Rice-Mele tight-binding model is used to rationalize the shift-current response for these systems, and its dependence on polarization, in general terms with implications for other polar materials

Cannabis as a Substitute for Opioid-Based Pain Medication: Patient Self-Report

Abstract: Introduction: Prescription drug overdoses are the leading cause of accidental death in the United States. Alternatives to opioids for the treatment of pain are necessary to address this issue. Cannabis can be an effective treatment for pain, greatly reduces the chance of dependence, and eliminates the risk of fatal overdose compared to opioid-based medications. Medical cannabis patients report that cannabis is just as effective, if not more, than opioid-based medications for pain. Materials and Methods: The current study examined the use of cannabis as a substitute for opioid-based pain medication by collecting survey data from 2897 medical cannabis patients. Discussion: Thirty-four percent of the sample reported using opioid-based pain medication in the past 6 months. Respondents overwhelmingly reported that cannabis provided relief on par with their other medications, but without the unwanted side effects. Ninety-seven percent of the sample “strongly agreed/agreed” that they are able to decreas...

TREM2 deficiency exacerbates tau pathology through dysregulated kinase signaling in a mouse model of tauopathy.

Abstract: Genetic variants of the Triggering Receptor Expressed on Myeloid Cells-2 (TREM2) confer increased risk of developing late-onset Alzheimer’s Disease (LOAD) and other neurodegenerative disorders. Recent studies provided insight into the multifaceted roles of TREM2 in regulating extracellular β-amyloid (Aβ) pathology, myeloid cell accumulation, and inflammation observed in AD, yet little is known regarding the role of TREM2 in regulating intracellular microtubule associated protein tau (MAPT; tau) pathology in neurodegenerative diseases and in AD, in particular. Here we report that TREM2 deficiency leads to accelerated and exacerbated hyperphosphorylation and aggregation of tau in a humanized mouse model of tauopathy. TREM2 deficiency also results, indirectly, in dramatic widespread dysregulation of neuronal stress kinase pathways. Our results suggest that deficiency of microglial TREM2 leads to heightened tau pathology coupled with widespread increases in activated neuronal stress kinases. These findings offer new insight into the complex, multiple roles of TREM2 in regulating Aβ and tau pathologies.

A literature review on stress and coping strategies in nursing students.

Abstract: Background: While stress is gaining attention as an important subject of research in nursing literature, coping strategies, as an important construct, has never been comprehensively reviewed.Aim: T...

Molecular and cellular reorganization of neural circuits in the human lineage

Abstract: To better understand the molecular and cellular differences in brain organization between human and nonhuman primates, we performed transcriptome sequencing of 16 regions of adult human, chimpanzee, and macaque brains. Integration with human single-cell transcriptomic data revealed global, regional, and cell-type–specific species expression differences in genes representing distinct functional categories. We validated and further characterized the human specificity of genes enriched in distinct cell types through histological and functional analyses, including rare subpallial-derived interneurons expressing dopamine biosynthesis genes enriched in the human striatum and absent in the nonhuman African ape neocortex. Our integrated analysis of the generated data revealed diverse molecular and cellular features of the phylogenetic reorganization of the human brain across multiple levels, with relevance for brain function and disease.

Vaccine Rejection and Hesitancy: A Review and Call to Action

Abstract: Vaccine refusal has been a recurring story in the media for well over a decade. Although there is scant evidence that refusal is genuinely increasing in the population, multiple studies have demonstrated concerning patterns of decline of confidence in vaccines, the medical professionals who administer vaccines, and the scientists who study and develop vaccines. As specialists in microbiology, immunology, and infectious diseases, scientists are content experts but often lack the direct contact with individuals considering vaccination for themselves or their children that healthcare professionals have daily. This review examines the arguments and players in the US antivaccination scene, and it discusses ways that experts in infectious diseases can become more active in promoting vaccination to friends, family, and the public at large.

Thermotropic liquid crystal films for biosensors and beyond

Abstract: We briefly review studies of liquid crystal films suspended in submillimeter size grids for biosensing applications and beyond. Due to intense recent research, the sensitivity of liquid crystal films to targeted biologically relevant agents can be increased, and the LC surface can be functionalized to be sensitive only to pre-assigned pathogens. Beyond sensor applications, we show that novel liquid crystal defect structures can be used to manipulate separation and deposition of lipids. Finally, we demonstrate that not only the nematic liquid crystal phase, but also chiral nematic (cholesteric and blue phase) and smectic liquid crystals can be used for sensing and may extend the sensitivity and/or the selection of biomaterials, which can be sensed.

Memantine for the Treatment of Dementia: A Review on its Current and Future Applications.

Abstract: Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the presence in the brain of extracellular amyloid-β protein (Aβ) and intracellular neurofibrillary tangles composed of hyperphosphorylated tau protein. The N-Methyl-D-aspartate receptors (NMDAR), ionotropic glutamate receptor, are essential for processes like learning and memory. An excessive activation of NMDARs has been associated with neuronal loss. The discovery of extrasynaptic NMDARs provided a rational and physiological explanation between physiological and excitotoxic actions of glutamate. Memantine (MEM), an antagonist of extrasynaptic NMDAR, is currently used for the treatment of AD jointly with acetylcholinesterase inhibitors. It has been demonstrated that MEM preferentially prevents the excessive continuous extrasynaptic NMDAR disease activation and therefore prevents neuronal cell death induced by excitotoxicity without disrupting physiological synaptic activity. The problem is that MEM has shown no clear positive effects in clinical applications while, in preclinical stages, had very promising results. The data in preclinical studies suggests that MEM has a positive impact on improving AD brain neuropathology, as well as in preventing Aβ production, aggregation, or downstream neurotoxic consequences, in part through the blockade of extrasynaptic NMDAR. Thus, the focus of this review is primarily to discuss the efficacy of MEM in preclinical models of AD, consider possible combinations of this drug with others, and then evaluate possible reasons for its lack of efficacy in clinical trials. Finally, applications in other pathologies are also considered.

Oxytocin and Vasopressin: Powerful Regulators of Social Behavior.

Abstract: For many, the terms oxytocin and vasopressin immediately evoke images of animals interacting with one another, as both of these neuropeptides have been implicated as being part of the neurochemical "glue" that socially binds animals. However, social environments and social interactions are complex and include behaviors that bring animals together as well as behaviors that keep animals apart. It is at the intersection of social context, social experience, and an individual's sex that oxytocin and vasopressin act to modulate social behavior and social cognition. In this review, this complexity will be explored across mammalian species, with a focus on social memory, cooperative behaviors, and competitive behaviors. Implications for humans as well as future directions will also be considered.

Gas adsorption properties of hybrid graphene-MOF materials.

Abstract: Nowadays, hybrid porous materials consisting of metal-organic frameworks (MOFs) and graphene nanosheets become more and more attractive because of their growing applications in adsorption, catalysis and related areas. Incorporation of graphene oxide into MOFs can provide benefits such as increased water resistance and thermal stability as well as enhanced surface area and adsorption properties. Graphene oxide is one of the best additives to other materials owing to its two main virtues: high atomic density and large amount of surface functional groups. Due to its dense array of atoms, graphene oxide can significantly increase dispersion forces in graphene-MOF materials, which is beneficial for adsorption of small molecules. This work presents a concise appraisal of adsorption properties of MOFs and graphene-MOF hybrids toward CO2, volatile organic compounds, hydrogen and methane. It shows that the graphene-MOF materials represent an important class of materials with potential applications in adsorption and catalysis. A special emphasis of this article is placed on their adsorption applications for gas capture and storage. A large number of graphene-MOF adsorbents has been so far explored and their appraisal could be beneficial for researchers interested in the development of hybrid adsorbents for adsorption-based applications.