Vinylene carbonate (VC) and polyethylene oxide (PEO) have been investigated as functional agents that mimic the solid electrolyte interphase (SEI) chemistry of silicon (Si). VC and PEO are known to ...contribute to the stability of Si-based lithium-ion batteries as an electrolyte additive and as a SEI component, respectively. In this work, covalent surface functionalization was achieved via a facile route, which involves ball-milling the Si particles with sacrificial VC and PEO. Thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy indicate that the additives are strongly bound to Si. In particular, MAS NMR shows Si–R or Si–O–R groups, which confirm functionalization of the Si after milling in VC or PEO. Particle size analysis by dynamic light scattering reveals that the additives facilitate particle size reduction and that the functionalized particles result in more stable dispersions based on zeta potential measurements. Raman mapping of the electrodes fabricated from the VC and PEO-coated active material with a polyacrylic acid (PAA) binder reveals a more homogenous distribution of Si and the carbon conductive additive compared to the electrodes prepared from the neat Si. Furthermore, the VC-milled Si strikingly exhibited the highest capacity in both half- and full-cell configurations, with more than 200 mAh g–1 measured capacity compared to the neat Si in the half-cell format. This is linked to an improved electrode processing based on the Raman and zeta potential measurements as well as a thinner SEI (with more organic components for the functionalized Si relative to the neat Si) based on XPS analysis of the cycled electrodes. The effect of binder was also investigated by comparing PAA with P84 (polyimide type), where an increased capacity is observed in the latter case.
A simple analytic model for the optical properties of gold is proposed. The model includes a minimum set of parameters necessary to represent the complex dielectric function of gold in the visible ...and near-uv regions. Explicit values for the parameters to reproduce the Johnson and Christy data Phys. Rev. B 6, 4370 (1972) on the optical properties of gold are provided.
Rural Active Living Meyer, M. Renée Umstattd; Moore, Justin B.; Abildso, Christiaan ...
Journal of public health management and practice,
2016 Sep-Oct, Letnik:
22, Številka:
5
Journal Article
Recenzirano
Odprti dostop
Rural residents are less physically active than their urban counterparts and disproportionately affected by chronic diseases and conditions associated with insufficient activity. While the ecological ...model has been successful in promoting and translating active living research in urban settings, relatively little research has been conducted in rural settings. The resulting research gap prohibits a comprehensive understanding and application of solutions for active living in rural America. Therefore, the purpose of this article was to assess the evidence base for an ecological model of active living for rural populations and outline key scientific gaps that inhibit the development and application of solutions. Specifically, we reexamined the 4 domains conceptualized by the model and suggest that there is a dearth of research specific to rural communities across all areas of the framework. Considering the limited rural-specific efforts, we propose areas that need addressing to mobilize rural active living researchers and practitioners into action.
Epithelium attachment to the tooth or abutment surface is necessary to form a biological seal preventing pathogens and irritants from penetrating the body and reaching the underlying soft tissues and ...bone, which in turn can lead to inflammation and subsequent bone resorption. The present review investigated oral wound closure and the role of micro-environment, saliva, crevicular fluid and microbiota in wound healing. The importance of the junctional epithelium (peri-implant epithelium) attachment to the abutment surface was investigated. Current research focuses on macro-design, surface-topography, surface-chemistry, materials, coatings and wettability to enhance attachment, since these optimised surface properties are expected to promote keratinocyte attachment and spreading through hemi-desmosome formation. Detailed studies describing the extent of junctional epithelium attachment - e.g. barrier function, hemi-desmosomes, epithelium quality, composition of the external basement membrane or ability of the epithelium to resist microbial penetration and colonisation - are not yet reported in animals due to ethical considerations, scalability, expense, technical challenges and limited availability of antibodies. In vitro studies generally include relatively simple 2D culture models, which lack the complexity required to draw relevant conclusions. Additionally, human organotypic 3D mucosa models are being developed. The present review concluded that more research using these organotypic mucosa models may identify relevant parameters involved in soft-tissue-abutment interactions, which could be used to study different macro-shapes and surface modifications. Such studies would bridge the gap between clinical, animal and traditional in vitro cell culture studies supporting development of abutments aiming at improved clinical performance.
In order to study the early stages of nanofuzz growth in fusion-plasma-facing tungsten, mirror-polished high-purity tungsten was exposed to 80eV helium at 1130°C to a fluence of 4×1024Hem−2. The ...previously smooth surface shows morphology changes, and grains form one of four qualitatively different morphologies: smooth, wavy, pyramidal or terraced/wide waves. Combining high-resolution scanning electron microscopy (SEM) observations to determine the morphology of each grain with quantitative measurement of the grain’s orientation via electron backscatter diffraction in SEM shows that the normal-direction crystallographic orientation of the underlying grain controls the growth morphology. Specifically, near-〈001〉 || normal direction (ND) grains formed pyramids, near-〈114〉 to 〈112〉 || ND grains formed wavy and stepped structures and near-〈103〉 || ND grains remained smooth. Comparisons to control specimens indicate no changes to underlying bulk crystallographic texture, and possible explanations of the structure growth, particularly loop-punching, are discussed. Future developments to control tungsten texture via thermomechanical processing, ideally obtaining a sharp near-〈103〉 || ND processing texture, may delay the formation of nanofuzz.
The expression of genes, both coding and noncoding, can be significantly influenced by RNA structural features of their corresponding transcripts. There is by now mounting experimental and some ...theoretical evidence that structure formation in vivo starts during transcription and that this cotranscriptional folding determines the functional RNA structural features that are being formed. Several decades of research in bioinformatics have resulted in a wide range of computational methods for predicting RNA secondary structures. Almost all state-of-the-art methods in terms of prediction accuracy, however, completely ignore the process of structure formation and focus exclusively on the final RNA structure. This review hopes to bridge this gap. We summarize the existing evidence for cotranscriptional folding and then review the different, currently used strategies for RNA secondary-structure prediction. Finally, we propose a range of ideas on how state-of-the-art methods could be potentially improved by explicitly capturing the process of cotranscriptional structure formation.
Targeting RNAs with small molecules represents a new frontier in drug discovery and development. The rich structural diversity of folded RNAs offers a nearly unlimited reservoir of targets for small ...molecules to bind, similar to small molecule occupancy of protein binding pockets, thus creating the potential to modulate human biology. Although the bacterial ribosome has historically been the most well exploited RNA target, advances in RNA sequencing technologies and a growing understanding of RNA structure have led to an explosion of interest in the direct targeting of human pathological RNAs. This review highlights recent advances in this area, with a focus on the design of small molecule probes that selectively engage structures within disease-causing RNAs, with micromolar to nanomolar affinity. Additionally, we explore emerging RNA-target strategies, such as bleomycin A5 conjugates and ribonuclease targeting chimeras (RIBOTACs), that allow for the targeted degradation of RNAs with impressive potency and selectivity. The compounds discussed in this review have proven efficacious in human cell lines, patient-derived cells, and pre-clinical animal models, with one compound currently undergoing a Phase II clinical trial and another that recently garnerd FDA-approval, indicating a bright future for targeted small molecule therapeutics that affect RNA function.
Targeting RNAs with small molecules, a new frontier in drug discovery and development.
A significant fraction of OB-type, main-sequence massive stars are classified as runaway and move supersonically through the interstellar medium (ISM). Their strong stellar winds interact with their ...surroundings, where the typical strength of the local ISM magnetic field is about 3.5-7 ...G, which can result in the formation of bow shock nebulae. We investigate the effects of such magnetic fields, aligned with the motion of the flow, on the formation and emission properties of these circumstellar structures. Our axisymmetric, magneto-hydrodynamical simulations with optically thin radiative cooling, heating and anisotropic thermal conduction show that the presence of the background ISM magnetic field affects the projected optical emission of our bow shocks at H... and Oiii ...5007 which become fainter by about 1-2 orders of magnitude, respectively. Radiative transfer calculations against dust opacity indicate that the magnetic field slightly diminishes their projected infrared emission and that our bow shocks emit brightly at 60 ...m. This may explain why the bow shocks generated by ionizing runaway massive stars are often difficult to identify. Finally, we discuss our results in the context of the bow shock of ... Ophiuchi and we support the interpretation of its imperfect morphology as an evidence of the presence of an ISM magnetic field not aligned with the motion of its driving star. (ProQuest: ... denotes formulae/symbols omitted.)
Active play and physical activity are important for preventing childhood obesity, building healthy bones and muscles, reducing anxiety and stress, and increasing self-esteem. Unfortunately, safe and ...accessible play places are often lacking in under-resourced communities. Play Streets (temporary closure of streets) are an understudied intervention that provide safe places for children, adolescents, and their families to actively play. This systematic review examines how Play Streets impact opportunities for children and adolescents to engage in safe active play and physical activity, and for communities and neighborhoods. Methods for evaluating Play Streets were also examined.
A systematic literature review was conducted in Academic Search Complete, CINHAL, PsycINFO, PubMED, Web of Science, and Google Scholar. Peer-reviewed intervention studies published worldwide were included if they were published in English, through December 2017 and documented free-to-access Play Streets or other temporary spaces that incorporated a designated area for children and/or adolescents to engage in active play. Systematic data extraction documented sample, implementation, and measurement characteristics and outcomes.
Of 180 reviewed abstracts, 6 studies met inclusion criteria. Studies were conducted in five different countries (n = 2 in U.S.), using mostly cross-sectional study designs (n = 4). Physical activity outcomes were measured in half of the studies; one used observational and self-report measures, and two used device-based and self-report measures. In general, Play Streets provided safe places for child play, increased sense of community, and when measured, data suggest increased physical activity overall and during Play Streets.
Play Streets can create safe places for children to actively play, with promise of increasing physical activity and strengthening community. Given the popularity of Play Streets and the potential impact for active play, physical activity, and community level benefits, more rigorous evaluations and systematic reporting of Play Streets' evaluations are needed.
Palladium-exchanged zeolites are candidate materials for passive NO x adsorption in automotive exhaust aftertreatment, where mononuclear Pd cations behave as precursors to the purported NO x ...adsorption sites. Yet, the structures of zeolite lattice binding sites capable of stabilizing mononuclear Pd2+ ions, and the mechanisms that interconvert agglomerated PdO and Pd domains into mononuclear Pd2+ ions during Pd redispersion treatments, remain incompletely understood. Here, we use a suite of spectroscopic methods and quantitative site titration techniques to characterize mononuclear and agglomerated Pd species on zeolites with varying material properties and treatment history. Aqueous-phase methods to introduce Pd onto NH4-form zeolites initially form mononuclear Pd(NH3)42+ complexes, but subsequent thermal treatments (573–723 K; air) lead to in situ formation of H2 that first reduces Pd2+ to metallic Pd domains, which are then oxidized by air to PdO domains. Progressive treatment of Pd-zeolites in air to higher temperatures (723–1023 K) converts larger fractions of agglomerated PdO to mononuclear Pd2+, as quantified by H2 temperature programmed reduction, because higher temperature treatments facilitate Pd redispersion toward deeper locations within chabazite (CHA) crystallites, which is corroborated by complementary titrimetric and spectroscopic data. Pd-CHA zeolites synthesized with similar bulk Pd and framework Al content, but varying framework Al arrangement, provide evidence that six-membered rings (6-MR) hosting paired Al sites (Al–O–(Si–O) x –Al, x = 1, 2) stabilize Pd2+ ions and that otherwise isolated Al sites can stabilize PdOH+ species, identifiable by an IR OH stretch at 3660 cm–1. These findings clarify the underlying chemical processes and gas environments that cause Pd agglomeration in zeolites and their subsequent redispersion to mononuclear Pd2+ ions, which prefer binding at 6-MR paired Al sites in CHA, and indicate that higher temperature air treatments lead to more uniform Pd spatial distributions throughout zeolite crystallites.
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