bluuebunny/crossref_metadata_2025_split huggingface dataset:
Software-defined radio for monitoring the condition of infrastructure elements
Authors: Роенков Д.Н. , Богданов Д.Р. 
Published: August 2024

Статья посвящена оценке возможных направлений применения программно-определяемого радио (SDR) на железнодорожном транспорте, в том числе организации мониторинга состояния элементов железнодорожной инфраструктуры с помощью SDR. Рассмотрен разработанный программно-аппаратный комплекс для мониторинга состояния элементов инфраструктуры с использованием SDR.
The article is devoted to the assessment of possible applications of software-defined radio (SDR) in railway transport, including the organization of monitoring the state of railway infrastructure elements using SDR. The developed hardware and software complex for monitoring the state of infrastructure elements using SDR is considered.
Gas hydrate dissociation prolongs acidification of the Anthropocene oceans
Authors: Boudreau Bernard P. , Luo Yiming , Meysman Filip J. R. , Middelburg Jack J. , Dickens Gerald R. 
Published: October 2015

AbstractAnthropogenic warming of the oceans can release methane (CH4) currently stored in sediments as gas hydrates. This CH4 will be oxidized to CO2, thus increasing the acidification of the oceans. We employ a biogeochemical model of the multimillennial carbon cycle to determine the evolution of the oceanic dissolved carbonate system over the next 13 kyr in response to CO2 from gas hydrates, combined with a reasonable scenario for long‐term anthropogenic CO2 emissions. Hydrate‐derived CO2 will appreciably delay the neutralization of ocean acidity and the return to preindustrial‐like conditions. This finding is the same with CH4 release and oxidation in either the deep ocean or the atmosphere. A change in CaCO3 export, coupled to CH4 release, would intensify the transient rise of the carbonate compensation depth, without producing any changes to the long‐term evolution of the carbonate system. Overall, gas hydrate destabilization implies a moderate additional perturbation to the carbonate system of the Anthropocene oceans.
The collapse of the midnight ionosphere and behavior of meridional neutral winds at Townsville over a full solar cycle
Authors: Dandenault P. B. , Richards P. G. 
Published: October 2015

AbstractThis paper investigates the causes of the sudden descent (midnight collapse) of the ionosphere at Townsville, Australia, during the equinox periods of years between 1970 and 1980. The collapse of hmF2 at midnight is found to occur on 89% of the 330 equinox nights that are investigated, and the mean magnitude of the midnight collapse is 84 km in the March equinox periods and 99 km in the September equinox periods. Observations of hmF2 are used to determine equivalent meridional neutral winds using a first principles physics model. Harmonic analysis of these derived winds reveals the existence of significant diurnal (24 h), semidiurnal (12 h), and terdiurnal (8 h) tidal components. The contribution of wind harmonics to the midnight collapse is determined by band‐pass filtering the winds to only allow certain tides and then modeling their effect on hmF2 near midnight. The results indicate that the diurnal, semidiurnal, and terdiurnal components of the meridional neutral wind all play a significant role at various times, but the effect of the 6 h wind component is minimal. The spectral analysis also reveals that the terdiurnal wind component becomes dominant during solar maximum. Electric fields do not appear to be responsible for the midnight hmF2 collapse because it is seldom seen at the near‐conjugate station of Akita, Japan.
Interfacial tension‐driven relaxation of magma foam: An experimental study
Authors: Otsuki Shizuka , Nakamura Michihiko , Okumura Satoshi , Sasaki Osamu 
Published: October 2015

AbstractTo improve our understanding of permeability evolution of magmas in a shallow volcanic conduit, we experimentally investigated the interfacial tension‐driven microstructural relaxation of foamed magma. By heating pumice cubes at temperatures of 800–1000°C and ≤6 MPa vapor pressure, we simulated magmas in interexplosion periods of vulcanian activity, including magmatic clasts welding within a shallow conduit. Outlines and internal pore microstructures of run products relaxed significantly in 3–5 and 30 min at 1000 and 900°C, respectively. In addition, self‐contraction was caused by the expulsion of pores connected to sample surfaces. As a result of self‐contraction, the porosity of 3 mm side pumice cubes decreased from 72 to 15% in 8 h at 900°C. For larger starting materials (9 mm side pumice cubes), multiple‐contraction units formed melt globs, which promoted the formation of connected pores with concave outward shapes between globs. In contrast to the interbubble network, such pores are expected to maintain high permeability on a macroscopic scale; therefore, magma outgassing could be facilitated. These interglob pores were pinched off due to gravitational compaction after 8–32 h at 1000°C. The rapid and drastic changes in pore microstructures via relaxation, contraction, and compaction processes may be responsible for vent plugging during vulcanian explosion cycles.
Modeling comprehensive chemical composition of weathered oil following a marine spill to predict ozone and potential secondary aerosol formation and constrain transport pathways
Authors: Drozd Greg T. , Worton David R. , Aeppli Christoph , Reddy Christopher M. , Zhang Haofei , Variano Evan , Goldstein Allen H. 
Published: October 2015

AbstractReleases of hydrocarbons from oil spills have large environmental impacts in both the ocean and atmosphere. Oil evaporation is not simply a mechanism of mass loss from the ocean, as it also causes production of atmospheric pollutants. Monitoring atmospheric emissions from oil spills must include a broad range of volatile organic compounds (VOC), including intermediate‐volatile and semivolatile compounds (IVOC, SVOC), which cause secondary organic aerosol (SOA) and ozone production. The Deepwater Horizon (DWH) disaster in the northern Gulf of Mexico during Spring/Summer of 2010 presented a unique opportunity to observe SOA production due to an oil spill. To better understand these observations, we conducted measurements and modeled oil evaporation utilizing unprecedented comprehensive composition measurements, achieved by gas chromatography with vacuum ultraviolet time of flight mass spectrometry (GC‐VUV‐HR‐ToFMS). All hydrocarbons with 10–30 carbons were classified by degree of branching, number of cyclic rings, aromaticity, and molecular weight; these hydrocarbons comprise ∼70% of total oil mass. Such detailed and comprehensive characterization of DWH oil allowed bottom‐up estimates of oil evaporation kinetics. We developed an evaporative model, using solely our composition measurements and thermodynamic data, that is in excellent agreement with published mass evaporation rates and our wind‐tunnel measurements. Using this model, we determine surface slick samples are composed of oil with a distribution of evaporative ages and identify and characterize probable subsurface transport of oil.
Coupled surface‐subsurface hydrologic measurements reveal infiltration, recharge, and discharge dynamics across the swash zone of a sandy beach
Authors: Heiss James W. , Puleo Jack A. , Ullman William J. , Michael Holly A. 
Published: October 2015

AbstractSwash‐groundwater interactions affect the biogeochemistry of beach aquifers and the transport of solutes and sediment across the beachface. Improved understanding of the complex, coupled dynamics of surface and subsurface flow processes in the swash zone is required to better estimate chemical fluxes to the sea and predict the morphological evolution of beaches. Simultaneous high‐frequency measurements of saturation, water table elevation, and the cross‐shore locations of runup and the boundary between the saturated and unsaturated beachface (surface saturation boundary) were collected on a sandy beach to link groundwater flow dynamics with swash zone forcing. Saturation and lysimeter measurements showed the dynamic response of subsurface saturation to swash events and permitted estimation of infiltration rates. Surface and subsurface observations revealed a decoupling of the surface saturation boundary and the intersection between the water table and the beachface. Surface measurements alone were insufficient to delineate the infiltration and discharge zones, which moved independently of the surface saturation boundary. Results show for the first time the motion and areal extent of infiltration and recharge zones, and constrain the maximum size of the subaerial discharge zone over swash and tidal time scales. The width of the infiltration zone was controlled by swash processes, and subaerial discharge was controlled primarily by tidal processes. These dynamics reveal the tightly coupled nature of surface and subsurface processes over multiple time scales, with implications for sediment transport and fluid and solute fluxes through the hydrologically and biogeochemically active intertidal zone of sandy beaches.
Experimental study on nonmonotonicity of Capillary Desaturation Curves in a 2‐D pore network
Authors: Rodríguez de Castro Antonio , Shokri Nima , Karadimitriou Nikolaos , Oostrom Mart , Joekar‐Niasar Vahid 
Published: October 2015

AbstractImmiscible displacement in porous media is important in many applications such as soil remediation and enhanced oil recovery. When gravitational forces are negligible, two‐phase immiscible displacement at the pore level is controlled by capillary and viscous forces whose relative importance is quantified through the dimensionless capillary number Ca and the viscosity ratio M between liquid phases. Depending on the values of Ca and M, capillary fingering, viscous fingering, or stable displacement may be observed resulting in a variety of patterns affecting the phase entrapment. The Capillary Desaturation Curve (CDC), which represents the relationship between the residual oil saturation and Ca, is an important relation to describe the phase entrapment at a given Ca. In the present study, we investigated the CDC as influenced by the viscosity ratio. To do so, we have conducted a comprehensive series of experiments using a high‐resolution microscope and state‐of‐art micromodels to investigate the dynamics and patterns of phase entrapment at different Ca and M. By postprocessing of the experimental high‐resolution images, we calculated the CDC and quantified the effects of the Ca and M on the phase entrapment and number of blobs trapped in the micromodel and their size distributions during immiscible two‐phase flow. Our results show that CDCs are not necessarily monotonic for all M, and the physical mechanisms causing this nonmonotonic behavior are discussed.
Tails of Three Knotty Switches: HowPreQ1Riboswitch Structures Control Protein Translation
Authors: Belashov Ivan A , Dutta Debapratim , Salim Mohammad , Wedekind Joseph E 
Published: October 2015

AbstractRiboswitches are structured RNA molecules that regulate genes by sensing cellular levels of metabolites such as preQ1(7‐aminomethyl‐7‐deazaguanine). This economical platform is found predominantly in the 5′‐leader sequences of bacterial mRNAs, attracting attention as a potential antibiotic target. Members of the preQ1riboswitch family provide exemplary insights into translational regulation because their high‐resolution structures have been determined, providing a framework to interpret complementary single‐molecule, computational and biochemical analyses. Although class I and II preQ1riboswitches possess divergent pseudoknot architectures, both appear to function by burying the Shine‐Dalgarno sequence (SDS) within a core aptamer domain upon preQ1binding. By contrast, the class III preQ1riboswitch binds its ligand in an aptamer distant from the SDS. PreQ1binding increases the population of riboswitches that transiently sequester the SDS, representing an alternative regulatory paradigm. Progress on preQ1riboswitches is described, along with expectations for interfacing a riboswitch with the ribosome for translation initiation.Key ConceptsRiboswitches are structured non‐protein‐coding RNAs that bind small molecules, tRNA or ions to control gene expression without the need for proteins.Riboswitches bind protein enzyme co‐factors suggesting that they are remnants of an ancient RNA world.Three classes of riboswitches bind the metabolite prequeuosine1(preQ1), a pyrrolopyrimidine made exclusively in bacteria as a precursor to the hypermodified base queuosine, which is used widely in the biosphere to confer translational fidelity.PreQ1riboswitches adopt pseudoknot folds in which ligand binding stabilises coaxial helical stacking.High‐resolution structures of class I, II and III preQ1riboswitches reveal their overall three‐dimensional folds, along with chemical details that explain their high‐affinity ligand binding.Structural observations suggest that riboswitches co‐opt traditional RNA tertiary interactions, such as major‐groove base‐triples and A‐minor motifs, for specialised biological functions.Class I and II preQ1riboswitches integrate Shine‐Dalgarno sequences (SDS) into their aptamer cores, producing gene off states in response to preQ1binding.Class III preQ1riboswitches fold with spatially disparate aptamer and expression platform sequences that do not commingle in response to ligand binding.Single‐molecule fluorescence resonance energy transfer (smFRET) provides insight into ligand‐dependent conformational changes of preQ1riboswitches that control gene expression.Modelling suggests that the class II preQ1riboswitch must unfold only its anti‐SDS⋅SDS helix to interact with the 16S ribosomal RNA.
Evolution of Microalgae and Their Adaptations in Different Marine Ecosystems
Authors: Hopes Amanda , Mock Thomas 
Published: October 2015

Abstract

Microalgae are unicellular eukaryotic organisms that are predominantly photosynthetic. They are found in a wide range of habitats, particularly marine ecosystems, and are responsible for a significant portion of the oceans biogeochemical cycling. Microalgae have a varied evolutionary history with genes derived from photosynthetic organisms, heterotrophic eukaryotes and bacteria. This has led to a wide range of adaptations, allowing them to thrive in a variety of conditions. Microalgae in coastal regions are adapted to turbulence, high nutrients and low light whilst open ocean microalgae have to contend with high irradiance and low nutrient concentrations. Polar microalgae are adapted to freezing temperatures, high nutrients and long periods of light and darkness. Microalgae genomes and transcriptomes uncover and interpret these adaptations, providing information on how microalgae have become a dominant force within marine ecosystems.

Key Concepts

Microalgae are very diverse and species rich

Microalgae are adapted to diverse environments

Microalgae have complex evolutionary origins

Microalgae significantly contribute to the global carbon cycle on Earth

Marine microalgae are the base of the marine food web
Electronically Matching C−H Alkylation Strategies for the Synthesis of α‐Heteroaryl Acetic Acid Derivatives
Authors: Jang Ha‐Lim , Kim Hyun Tae , Cho Eun Jin , Joo Jung Min 
Published: October 2015

AbstractA strategy in which complementary species are paired for the preparation of α‐heteroaryl esters and amides from heteroarenes was developed. Readily available α‐haloacetates and α‐acetamides provided the requisite acetate and acetamide groups via three distinctive reactive species, namely nucleophilic carbanions, alkylpalladium complexes, and photoredox‐generated electrophilic radicals. Based on their electronic properties, these intermediates were matched with various five‐membered heteroarenes, such as pyrazoles, imidazoles, thiophenes, furans, pyrroles, and indoles. These flexible protocols offer easy access to α‐heteroaryl acetic acid derivatives and expand the scope of heteroarenes that can be utilized for C−H alkylation.
Structure–property relationship of sodium deoxycholate based poly(ester ether)urethane ionomers for biomedical applications
Authors: Filip Daniela , Macocinschi Doina , Vlad Stelian , Lisa Gabriela , Cristea Mariana , Zaltariov Mirela F. 
Published: October 2015

ABSTRACTNew sodium deoxycholate based poly(ester ether)urethane ionomers were prepared for the development of biomedical materials. A structure–property relationship in the tested biomaterials was established by cross‐examination of the dynamic mechanical and dielectric properties, attenuated total reflection–Fourier transform infrared investigation, thermogravimetric analysis, and surface morphology characterization. A stronger ionic interaction and solvation capacity of the ions and a higher ionic conductivity were manifested in the case of poly(ethylene oxide)‐rich segments than for poly(propylene oxide)‐rich segments in these polyurethane ionomers. The molecular and ionic interactions of the bile‐salt moiety with different polyether cosoft segments influenced chain packing and conformation, supramolecular organization, and the resulting surface morphological microstructures of the polyurethane biomembranes. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42921.
Physical properties of polypropylene composites with hydrophobized cellulose powder by soybean oil
Authors: Jang Song Yi , Kim Dae Su 
Published: October 2015

ABSTRACTCellulose materials have attracted lots of interest as potential natural fillers in the production of green polymer composites because they are ecofriendly and economic. In this study, to improve the interfacial bonding strength between cellulose powder and a hydrophobic polypropylene (PP) matrix, the surface hydrophobization of cellulose powder by soybean oil was carried out via a simple transesterification reaction procedure. Weight change measurements, Fourier transform infrared spectroscopy, and compatibility testing were used to quantitatively and qualitatively analyze the hydrophobization of the cellulose powder. By changing the hydrophobization conditions, the soybean oil content attached to the cellulose powder changed from 8.0 to 57.8%. PP composites with 20% of each hydrophobized cellulose powder were prepared by melt blending followed by compression molding. The mechanical properties of the PP composites were investigated with a universal testing machine and an Izod impact tester. Compared to the composite with pristine cellulose powder, the PP composite with the hydrophobized cellulose powder and an attached soybean oil content of 29.6% showed largely increased impact strength (46.3%), tensile strength (47.5%), and elongation at break (27.3%) values. The scanning electron microscopy images for the fracture surfaces of the composites showed that the hydrophobization induced much stronger interfacial bonding between the PP matrix and cellulose powder. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42929.
Polysulfone/poly(ether sulfone) blended membranes for CO2 separation
Authors: Abdul Mannan Hafiz , Mukhtar Hilmi , Shima Shaharun Maizatul , Roslee Othman Mohd , Murugesan Thanabalan 
Published: October 2015

ABSTRACTPolymer blending as a modification technique is a useful approach for augmenting the gas‐separation and permeation properties of polymeric membranes. Polysulfone (PSF)/poly(ether sulfone) (PES) blend membranes with different blend ratios were synthesized by conventional solution casting and solvent evaporation technique. The synthesized membranes were characterized for miscibility, morphology, thermal stability, and spectral properties by differential scanning calorimetry (DSC), field emission scanning electron microscopy, thermogravimetric analysis, and Fourier transform infrared (FTIR) spectroscopy, respectively. The permeation of pure CO2 and CH4 gases was recorded at a feed pressure of 2–10 bar. The polymer blends were miscible in all of the compositions, as shown by DSC analysis, and molecular interaction between the two polymers was observed by FTIR analysis. The thermal stability of the blend membranes was found to be an additive property and a function of the blend composition. The morphology of the blend membranes was dense and homogeneous with no phase separation. Gas‐permeability studies revealed that the ideal selectivity was improved by 65% with the addition of the PES polymer in the PSF matrix. The synthesized PSF/PES blend membranes provided an optimized performance with a good combination of permeability, selectivity and thermal stability. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42946.
Free volume and damping in a miscible high performance polymer blend: Positron annihilation lifetime and dynamic mechanical thermal analysis studies
Authors: Ramani Ramasubbu , Alam Sarfaraz 
Published: October 2015

ABSTRACTHigh performance polymer blend of poly(ether ether ketone) (PEEK) and poly(ether imide) (PEI) was examined for their free volume behavior at different compositions of PEI using positron annihilation lifetime spectroscopy (PALS). The damping property of the blend was studied using tan‐δ obtained from dynamic mechanical thermal analysis (DMTA). The dependence of tan‐δ on temperature revealed that the blend is miscible in all compositions, in agreement with earlier studies. The tan‐δ peak height is found to increase with increase in free volume fraction for the entire blend composition signifying that the free volume plays an imperative role in understanding the damping property. Using DMTA, master curves were obtained at a reference temperature T0 by applying the time‐temperature‐superposition (TTS) using Williams‐Landel‐Ferry (WLF) relationship. From the shift factor aT, the WLF coefficients
and
were evaluated, using which the free volume fraction was found. Both PALS and DMTA methods were found to give similar results for the dependence of free volume for various PEI contents studied in this blend. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42961.
Novel polyethylene‐b‐polyurethane‐b‐polyethylene triblock copolymers: Facile synthesis and application
Authors: Xu Zhixian , Liu Yulu , Guo Song , Jie Suyun , Li Bo-Geng 
Published: October 2015

ABSTRACTA series of novel polyethylene‐b‐polyurethane‐b‐polyethylene (EUE) triblock copolymers is successfully prepared through a facile route combining the thiol‐ene chemistry, addition polymerization, and coupling reaction. The resulting EUE triblock copolymers are characterized by Nuclear magnetic resonance (1H NMR), Fourier transform‐infrared spectra (FT‐IR), High temperature gel permeation chromatography (HT‐GPC), Differential scanning calorimetry (DSC), Thermogravimetric analysis (TGA), and Transmission electron microscopy (TEM). In addition, the EUE triblock copolymers have been evaluated as compatibilizers in the polymer blends of thermoplastic polyurethane elastomer (TPU) and high‐density polyethylene (HDPE). The SEM results show that the compatibility of immiscible blends is enhanced greatly after the addition of EUE triblock copolymers. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2016,133, 42967.