bluuebunny/crossref_metadata_2025 huggingface dataset:
The Saccharomyces cerevisiae poly (A) binding protein (Pab1): Master regulator of mRNA metabolism and cell physiology
Authors: Brambilla Marco , Martani Francesca , Bertacchi Stefano , Vitangeli Ilaria , Branduardi Paola
Published: July 2018

Pab1, the major poly (A) binding protein of the yeast Saccharomyces cerevisiae, is involved in many intracellular functions associated with mRNA metabolism, such as mRNA nuclear export, deadenylation, translation initiation and termination. Pab1 consists of four RNA recognition motifs (RRM), a proline‐rich domain (P) and a carboxy‐terminal (C) domain. Due to its modular structure, Pab1 can simultaneously interact with poly (A) tails and different proteins that regulate mRNA turnover and translation. Furthermore, Pab1 also influences cell physiology under stressful conditions by affecting the formation of quinary assemblies and stress granules, as well as by stabilizing specific mRNAs to allow translation re‐initiation after stress. The main goal of this review is to correlate the structural complexity of this protein with the multiplicity of its functions.
First aspects on acetate metabolism in the yeast Dekkera bruxellensis: a few keys for improving ethanol fermentation
Authors: Teles Gilberto Henrique , da Silva Jackeline Maria , Mendonça Allyson Andrade , de Morais Junior Marcos Antonio , de Barros Pita Will
Published: July 2018

Dekkera bruxellensis is continuously changing its status in fermentation processes, ranging from a contaminant or spoiling yeast to a microorganism with potential to produce metabolites of biotechnological interest. In spite of that, several major aspects of its physiology are still poorly understood. As an acetogenic yeast, minimal oxygen concentrations are able to drive glucose assimilation to oxidative metabolism, in order to produce biomass and acetate, with consequent low yield in ethanol. In the present study, we used disulfiram to inhibit acetaldehyde dehydrogenase activity to evaluate the influence of cytosolic acetate on cell metabolism. D. bruxellensis was more tolerant to disulfiram than Saccharomyces cerevisiae and the use of different carbon sources revealed that the former yeast might be able to export acetate (or acetyl‐CoA) from mitochondria to cytoplasm. Fermentation assays showed that acetaldehyde dehydrogenase inhibition re‐oriented yeast central metabolism to increase ethanol production and decrease biomass formation. However, glucose uptake was reduced, which ultimately represents economical loss to the fermentation process. This might be the major challenge for future metabolic engineering enterprises on this yeast.
A study of time reversal symmetry of abelian anyons
Authors: Lee Yasunori , Tachikawa Yuji
Published: July 2018

Abstract

We perform a study of time reversal symmetry of abelian anyons

$$ \mathcal{A} $$

A

in 2+1 dimensions, in the spin structure independent cases. We will find the importance of the group

$$ \mathcal{C} $$

C

of time-reversal-symmetric anyons modulo anyons composed from an anyon and its time reversal. Possible choices of local Kramers degeneracy are given by quadratic refinements of the braiding phases of

$$ \mathcal{C} $$

C

, and the anomaly is then given by the Arf invariant of the chosen quadratic refinement. We also give a concrete study of the cases when |

$$ \mathcal{A} $$

A

| is odd or

$$ \mathcal{A}={\left({\mathrm{\mathbb{Z}}}_2\right)}^N $$

A
=

ℤ
2

N

.
Massive spin 2 excitations in AdS6 × S2 warped spacetimes
Authors: Gutperle Michael , Uhlemann Christoph F. , Varela Oscar
Published: July 2018

Abstract

We study (massive) spin-2 fluctuations around warped AdS
6 solutions with 16 supersymmetries in type IIB supergravity. We identify two classes of fluctuations which are universally present for all solutions of this form. The holographically dual operators have scaling dimensions Δ = 5 + 3ℓ and Δ = 6 + 3ℓ, where the integer ℓ encodes the R-symmetry charge. They are identified as descendant states in respective BPS multiplets (the current multiplet for Δ = 5). We also compute the normalization of the energy-momentum tensor two-point function and show that it is related to the S
5 partition function of the dual 5d SCFTs.
A viable QCD axion in the MeV mass range
Authors: Alves Daniele S. M. , Weiner Neal
Published: July 2018

Abstract

The QCD axion is one of the most compelling solutions of the strong CP problem. There are major current efforts into searching for an ultralight,invisibleaxion, which is believed to be the only phenomenologically viable realization of the QCD axion.Visibleaxions with decay constants at or below the electroweak scale are believed to have been long excluded by laboratory searches. Considering the significance of the axion solution to the strong CP problem, we revisit experimental constraints on QCD axions in the$$ \mathcal{O} $$O(10 MeV) mass window. In particular, we find a variant axion model that remains compatible with existing constraints. This model predicts new states at the GeV scale coupled hadronically, and a variety of low-energy axion signatures, such as rare meson decays, nuclear de-excitations via axion emission, and production ine+e−annihilation and fixed target experiments. This reopens the possibility of solving the strong CP problem at the GeV scale.
Constraining anomalous gluon self-interactions at the LHC: a reappraisal
Authors: Hirschi Valentin , Maltoni Fabio , Tsinikos Ioannis , Vryonidou Eleni
Published: July 2018

Abstract

Anomalous self-interactions of non-abelian gauge fields can be described by higher dimensional operators featuring gauge-invariant combinations of the field strengths. In the case of QCD, the gluon self-interactions start to be modified at dimension six by operators of the type GGG, with G the gluon field strength tensor, possibly leading to deviations in all observables and measurements that probe strong interactions at very small distances. In this work we consider the sensitivity to the triple gluon operator of a series of observables at the LHC in di-jet, three- and multi-jet final states and heavy-quark production. We critically re-examine the robustness of long-standing as well as more recent proposals addressing issues such as the validity of the EFT expansion and the impact of higher order QCD corrections. Our results support the conclusion that multi-jet observables can reliably bound these anomalous interactions to the level that their impact on other key observables at the LHC, involving for example top quark and Higgs production, can be safely neglected. We also highlight the potential of using previously suggested angular observables in three-jet events at the LHC to further constrain these interactions.
Tensor models for black hole probes
Authors: Halmagyi Nick , Mondal Swapnamay
Published: July 2018

Abstract

The infrared dynamics of the SYK model, as well as its associated tensor models, exhibit some of the non trivial features expected of a holographic dual of near extremal black holes. These include developing certain symmetries of the near horizon geometry and exhibiting maximal chaos. In this paper we present a generalization of these tensor models to include fields with fewer tensor indices and which can be thought of as describing probes in a black hole background. In large N limit, dynamics of the original model remain unaffected by the probe fields and some of the four point functions involving probe fields exhibit maximal chaos, a non trivial feature expected of a black hole probe.
Exactly solvable gravitating perfect fluid solitons in (2 + 1) dimensions
Authors: Adam C. , Romanczukiewicz T. , Wachla M. , Wereszczynski A.
Published: July 2018

Abstract

The Bogomolnyi-Prasad-Sommerfield (BPS) baby Skyrme model coupled to gravity is considered. We show that in an asymptotically flat space-time the model still possesses the BPS property, i.e., admits a BPS reduction to first order Bogomolnyi equations, which guarantees that the corresponding proper energy is a linear function of the topological charge. We also find the mass-radius relation as well as the maximal mass and radius. All these results are obtained in an analytical manner, which implies the complete solvability of this selfgravitating matter system.

If a cosmological constant is added, then the BPS property is lost. In de Sitter (dS ) space-time both extremal and non-extremal solutions are found, where the former correspond to finite positive pressure solutions of the flat space-time model. For the asymptotic anti-de Sitter (AdS ) case, extremal solutions do not exist as there are no negative pressure BPS baby Skyrmions in flat space-time. Non-extremal solutions with AdS asymptotics do exist and may be constructed numerically. The impact of the negative cosmological constant on the mass-radius relation is studied. We also found two potentials for which exact multi-soliton solutions in the external AdS space can be obtained. Finally, we elaborate on the implications of these findings for certain three-dimensional models of holographic QCD.
Two-stage oxygen supply strategy based on energy metabolism analysis for improving acetic acid production by Acetobacter pasteurianus
Authors: Zheng Yu , Chang Yangang , Zhang Renkuan , Song Jia , Xu Ying , Liu Jing , Wang Min
Published: July 2018

Oxygen acts as the electron acceptor to oxidize ethanol by acetic acid bacteria during acetic acid fermentation. In this study, the energy release rate from ethanol and glucose under different aerate rate were compared, and the relationship between energy metabolism and acetic acid fermentation was analyzed. The results imply that proper oxygen supply can maintain the reasonable energy metabolism and cell tolerance to improve the acetic acid fermentation. Further, the transcriptions of genes that involve in the ethanol oxidation, TCA cycle, ATP synthesis and tolerance protein expression were analyzed to outline the effect of oxygen supply on cell metabolism of Acetobacter pasteurianus. Under the direction of energy metabolism framework a rational two-stage oxygen supply strategy was established to release the power consumption and substrates volatilization during acetic acid fermentation. As a result, the acetic acid production rate of 1.86 g/L/h was obtained, which were 20.78% higher than that of 0.1 vvm one-stage aerate rate. And the final acetic acid concentration and the stoichiometric yield were 88.5 g/L and 94.1%, respectively, which were 84.6 g/L and 89.5% for 0.15 vvm one-stage aerate rate.
Knowing how things might have been
Authors: Jago Mark
Published: July 2018

I know that I could have been where you are right now and that you could have been where I am right now, but that neither of us could have been turnips or natural numbers. This knowledge of metaphysical modality stands in need of explanation. I will offer an account based on our knowledge of the natures, or essencess, of things. I will argue that essences need not be viewed as metaphysically bizarre entities; that we can conceptualise and refer to essences; and that we can gain knowledge of them. We can know about which properties are, and which properties are not, essential to a given entity. This knowledge of essence offers a route to knowledge of the ways those entities must be or could be.
Gas Absorption Center-Based Wavelength Calibration Technique in QEPAS System for SNR Improvement
Authors: Wang Zongliang , Chang Jun , Liu Qi , Tian Cunwei , Zhang Qinduan
Published: July 2018

A simple and effective wavelength calibration scheme is proposed in a quartz enhanced photoacoustic spectroscopy (QEPAS) system for trace gas detection. A reference gas cell is connected an InGaAs photodetector for detecting the absorption intensity peak caused by the gas to calibrate the gas absorption center using distributed feedback laser diode (DFB-LD) with sawtooth wave driver current. The gas absorption wavelength calibration and gas sensing operations are conducted at a special internal to eliminate the wavelength shift of DFB-LD caused by the ambient fluctuations. Compared with the conventional wavelength modulation spectroscopy (WMS), this method uses a lower lock-in amplifier bandwidth and averaging algorithm to improve signal noise ratio (SNR). Water vapor is chosen as a sample gas to evaluate its performance. In the experiments, the impact of sawtooth wave frequency and lock-in amplifier bandwidth on the harmonic signal is analyzed, and the wavelength-calibration technique-based system achieves a minimum detection limit (MDL) of 790 ppbv and SNR with 13.4 improvement factor compared with the conventional WMS system.
Crust structure of the northeastern Barents Sea basin area
Authors: Piskarev A.L. , Kireev A.A. , Savin V.A. , Smirnov O.E.
Published: July 2018

Processing of data from regional geophysical surveys completed in the northern Barents Sea has provided updates to gravity and magnetic databases, structural maps of seismic interfaces, and positions of anomaly sources, which made a basis for 3D density and magnetic models of the crust. The new geological and geophysical results placed constraints on the boundaries between basement blocks formed in different settings and on the contours of deposition zones of different ages in the northeastern Barents Sea. The estimated thicknesses of sedimentary sequences that formed within certain time spans record the deposition history of the region. There is a 20–50 km wide deep suture between two basins of Mesozoic and Paleozoic ages in the eastern part of the region, where pre-Late Triassic reflectors have no clear correlation. The suture slopes eastward at a low angle and corresponds to a paleothrust according to seismic and modeling data. In the basement model, the suture is approximated by a zone of low magnetization and density, which is common to active fault systems. The discovery of the suture has important geological and exploration implications.
The Maurynya section, West Siberia: a key section of the Jurassic–Cretaceous boundary deposits of shallow marine genesis
Authors: Dzyuba O.S. , Pestchevitskaya E.B. , Urman O.S. , Shurygin B.N. , Alifirov A.S. , Igolnikov A.E. , Kosenko I.N.
Published: July 2018

The Maurynya section exposed on the northwestern margin of West Siberia is one of few continuous sections of the Jurassic–Cretaceous boundary deposits in Boreal regions. In the meantime, it can be considered a reference section for the transitional Volgian–Ryazanian beds formed in shallow water environments of the West Siberian sea basin. This study is a synthesis of the new data with previous results of lithologic, paleontological, biostratigraphic, and (O, C, Sr) isotope studies of the Upper Volgian–lowermost Ryazanian of the Maurynya section. It has been established that the beginning of the Cretaceous (corresponding to the middle Late Volgian) is associated with a sharp increase in species number and diversity of cephalopods and bivalve mollusks on the northwestern margin of the West Siberian sea basin. This can be explained by an increase in its depths and their stabilization at a level which appeared optimal for the habitat of nekton, nektobenthos, and benthic fauna communities, superimposed on the general trend of warming. At the same time, the percentage of phytoplankton significantly increased, indicating the onset of transgression, which affected largely coastal landscapes and type of vegetation: The forests dominated by conifers were gradually succeeded by forests mostly composed of Ginkgoaceae.
Foraging choices balanced between resource abundance and handling concerns: how the honeybee, Apis mellifera, select the flowers of Robinia pseudoacacia
Authors: Giovanetti M.
Published: July 2018

Nectar is a main resource harvested by foraging honeybees: their ability in selecting among flowers is the key to optimize resource collection. This ability is expected to be the result of co-evolutionary traits between the plant and the pollinator visiting it; notwithstanding, novel interactions may occur between native and invasive species. Analysing foraging efforts, flexibility and individual constrains has to be taken into account. The foraging pattern of the ubiquitous honeybee on Robinia pseudoacacia, a North-American species widely naturalized in European countries, grounds a perfect case study. The plant shows papilionate flowers especially reach in nectar, but their tripping mechanism is difficult for the small/light-weight honeybee. Yet Apis mellifera is known to pay frequent and constant visits to them: in fact, one of the most appreciated unifloral honey is produced out of R. pseudoacacia. The aim of this study was to understand when and how the bees overcome physical constraints to succeed in flower visits, and to what extent this flexibility extend from the individual to the species. Data were collected in Italy, through focal observations of foraging individuals, nectar content measurements and experiments with manipulated inflorescences. Results clearly indicate that nectar content changes accordingly to the state of flowers (visited or unvisited), which also show slight changes in appearance. Foraging individuals, able to detect these differences, perform active choices preferentially selecting already-visited flowers: lower in nectar content but easier to manipulate. Even if the choice is primarily driven by handling constraints, individual experience and strength of stimuli are prompting visits also to unvisited flowers, notwithstanding a higher risk of failure in resource collection. Behavioural plasticity matching a satisfactory compromise grounds the decision that maximizes the intake of resource balanced with the effort to gain it.
Statistical Characteristics of Gravity Waves With Near‐Inertial Frequencies in the Antarctic Troposphere and Lower Stratosphere Observed by the PANSY Radar
Authors: Minamihara Y. , Sato K. , Tsutsumi M. , Sato T.
Published: July 2018

Gravity waves (GWs) have temporally and spatially small scales. Observations of GWs have been limited especially in the polar region due to its harsh environment. The purpose of this study is to elucidate the statistical characteristics of GWs in the Antarctic troposphere and lower stratosphere based on the continuous data over a year from 1 October 2015 to 30 September 2016 using the full system of the Program of the Antarctic Syowa MST/IS Radar (PANSY) radar at Syowa Station (69.0°S, 39.6°E). Such continuous observations over a long duration are unprecedented for high‐power Mesosphere‐Stratosphere‐Troposphere (MST) radars at any latitude. The frequency power spectra of horizontal wind fluctuations reveal a clear isolated maximum around the inertial frequency (f) in the lower stratosphere. A statistical analysis is performed, focusing on the GWs with near‐inertial frequencies (NIGWs) that are dominant in the lower stratosphere. According to the results of hodograph analyses, there are a considerable proportion of NIGWs propagating energy downward in the upper troposphere during all seasons, as well as in the winter stratosphere above a height of 15 km, whereas NIGWs with upward group velocities are dominant in the lower troposphere and the lowermost stratosphere. These results suggest that there are NIGW sources on the ground and around the tropopause during all seasons and in the stratosphere and/or above in winter. Plausible candidates for these sources are topography, the tropospheric jet, and the polar night jet. The statistical characteristics of NIGWs, such as horizontal phase velocity, provide powerful support for our inferences of wave sources.
Relationships Between DOC and CDOM Based on the Total Carbon‐Specific Fluorescence Intensities for River Waters Across China
Authors: Zhao Ying , Song Kaishan
Published: July 2018

Weak correlations between chromophoric dissolved organic matter (CDOM) absorption coefficient a(440) and dissolved organic carbon (DOC) were observed due to weak absorption for river waters especially in the Qinghai‐Tibetan Plateau, and thus, it is impossible to estimate DOC concentrations by CDOM absorption across China. Therefore, it is necessary to estimate DOC concentrations through the fluorescent fraction of CDOM (i.e., FDOM). FDOM was proposed as a new method for estimation of large‐scale DOC concentrations in river waters across China. A total of 301 water samples from eight river basins across China were selected to assess FDOM by excitation‐emission matrix (EEM) fluorescence. Five fluorescent regions were obtained by EEM coupled with fluorescence regional integration (FRI) (EEM‐FRI) method. However, weak correlations between the fluorescence intensities FR(1–5), FSUM, and DOC concentrations were observed for all water samples, respectively. Therefore, the total carbon‐specific fluorescence intensities FSUM/DOC were used to establish relationships between DOC and FDOM. All 301 water samples excluding five outliers with FSUM/DOC higher than 8,000 nm/(mg/L)) were divided into four groups based on the threshold values for FSUM/DOC, and strong positive correlations between FSUM and DOC were observed in each group (R2 = 0.843, FSUM/DOC < 1,000 nm/(mg/L); R2 = 0.928, 1,000 < FSUM/DOC < 2,000 nm/(mg/L); R2 = 0.964, 2,000 < FSUM/DOC < 3,000 nm/(mg/L); and R2 = 0.953, 3,000 < FSUM/DOC < 8,000 nm/(mg/L)), respectively. This result indicated that the riverine DOC concentrations on large‐scale across China can be estimated directly by FDOM properties.
The Dewatering of the Fucino Lake Did Not Promote the M7.1 1915 Fucino Earthquake: Insights From Numerical Simulations
Authors: Cucci L. , Currenti G. , Palano M. , Tertulliani A.
Published: July 2018

The powerful M7.1 earthquake that devastated the Fucino Basin (Central Italy) in 1915 results to be the only (except for a M5.7 event in 1904) remarkable event to have occurred in that area, according to the 900‐year‐long record of the Italian Seismic Catalogue. Curiously, the 1915 event occurred only 38 years after the complete man‐induced dewatering of the largest lake of peninsular Italy, which formerly occupied the basin. Hence, we investigate on a possible relationship between the dewatering of the lake and the occurrence of the 1915 earthquake. We perform some numerical simulations in order to estimate the stress changes induced by the dewatering of the Fucino Lake and by the 1904 earthquake. We compute the stress changes on two different seismogenic sources selected among the ones proposed in the literature. Our main results support that (1) the dewatering process has reduced effects of the state of stress in the area before the 1915 earthquake, (2) the primary effect of the dewatering on both sources is a decrease of stresses that hampers the slip on the fault planes, and (3) the positive stress changes associated to the 1904 event would be too weak to influence the occurrence of the 1915 earthquake. We also suggest that the dewatering may have delayed by ~1.7 years the 1915 earthquake occurrence.
Icy Interactions
Authors: Fyke Jeremy , Sergienko Olga , L�fverstr�m Marcus , Price Stephen , Lenaerts Jan
Published: July 2018

Complex interactions between ice sheets and other components of the Earth system determine how ice sheets contribute to sea level rise.
AGU and AAS Join Forces to Foster Understanding of Exoplanets
Authors: Speiser Joshua
Published: July 2018

Enhanced cooperation between organizations representing astronomers and Earth and space scientists will build upon interdisplinary work already bridging geophysics and astronomy.
Three‐Dimensional Hybrid Simulation of Viscous‐Like Processes at Saturn's Magnetopause Boundary
Authors: Delamere P. A. , Burkholder B. , Ma X.
Published: July 2018

Saturn's magnetosheath flows exhibit significant dawn/dusk asymmetry. The dawnside flows are reduced from expectation, suggesting significant momentum transport through the magnetopause boundary where the flow shear is maximized. It has been suggested that the solar wind interaction with the giant magnetospheres is, in fact, dominated by a viscous‐like interaction governed by the Kelvin‐Helmholtz instability. In three dimensions, the Kelvin‐Helmholtz instability can generate small‐scale and intermittent magnetic reconnection due, in part, to a twisted magnetic field topology. The net result is a field line threading of the magnetopause boundary and the generation of Maxwell shear stresses. Here we present three‐dimensional hybrid simulations (kinetic ions and massless fluid electrons) of conditions similar to Saturn's dawnside magnetopause boundary to quantify the viscous‐like, tangential drag. Using model‐determined momentum fluxes, we estimate the effect on dawnside sheath flows and find very good agreement with observations.
Global Three‐Dimensional Simulation of the Earth's Magnetospheric and Ionospheric Responses to Small‐Scale Magnetic Flux Ropes in the Solar Wind
Authors: Park Kyung Sun , Lee Dae‐Young , Kim Myeong Joon , Choi Cheong Rim , Kim Rok Soon , Cho Kyungsuk , Choi Kyu‐Cheol , Kim Jaehun
Published: July 2018

The orientation of magnetic flux ropes in the solar wind is an important component that affects interactions with the Earth's magnetosphere and ionosphere. In this study, we performed global magnetohydrodynamic (MHD) simulations on the responses of the magnetosphere and ionosphere to the impact of small‐scale magnetic flux ropes (SMFRs). We considered four types of SMFR structures according to the alignment direction of the flux rope axis in the plane perpendicular to the Sun‐Earth line. The flux rope axis of the two types is oriented in the north‐south direction, while the flux rope axis of the other two types is oriented along the dusk‐dawn direction. Accordingly, the By and Bz profiles of the SMFR types vary as the SMFR passes through the Earth. The main features of the response are as follows: (i) The magnetic reconnection on both the dayside and nightside is well organized by the specific profiles of By and Bz. (ii) One type of SMFRs where Bz turns from south to north and By remains duskward leads to plasmoid formation in the tail, distinguishing it from the other types. (iii) The temporal responses of the tail plasma flow, cross‐tail electric field, tail plasma pressure, and cross‐polar cap potential depend on the specific profiles of By and Bz, causing different response times. (iv) The evolution of ionospheric convection pattern sensitively depends on the magnetic field variation within SMFRs. (v) The peak value of cross‐polar cap potential ranges from 25 kV to >50 kV, providing energy storage suitable for substorm expansion.
Comparing Two Intervals of Exceptionally Strong Solar Rotation Recurrence of Galactic Cosmic Rays
Authors: Gil A. , Mursula K.
Published: July 2018

Two intervals of exceptionally strong recurrence of galactic cosmic ray (GCR) intensity at solar rotation period stand out in recent history, one in 2007–2008 and the other in 2014–2015. We use neutron monitor data from Oulu and Hermanus, solar wind (SW) data, and coronal images to study these intervals. We find that in both cases the source of solar rotation period recurrence was a coronal hole (CH), but CH structures were different. While a large, longitudinally asymmetric CH existed at high southern latitudes in 2014–2015, a low‐latitude CH caused the recurrence in 2007–2008. Spectral properties of GCR and SW parameters reflect these differences. In 2014–2015 the GCR power spectrum density was broad and peaked at a period of 28.9 days, longer than the simultaneous recurrence period of SW speed. In 2007–2008 the GCR power spectrum was narrow and peaked at 27.5 days, exactly the same as for SW speed. The effect of CHs to GCRs was somewhat different in the two cases because of opposite solar polarities in the two intervals. In 2014–2015, during positive polarity when GCRs drift inward from high latitudes, the convection of fast SW from CH reduces the inward GCR drift over a wide range of high heliolatitudes at certain heliolongitudes. In 2007–2008, during negative polarity when GCRs drift inward via the heliospheric current sheet, a low‐latitude CH depletes the GCR flux not only by convection but also by the deflecting heliospheric current sheet away from the ecliptic, whence GCR drift to higher latitudes in a limited longitude range.
Heterogeneity in Warm‐Season Land‐Atmosphere Coupling Over the U.S. Southern Great Plains
Authors: Tang Qi , Xie Shaocheng , Zhang Yunyan , Phillips Thomas J. , Santanello Joseph A. , Cook David R. , Riihimaki Laura D. , Gaustad Krista L.
Published: July 2018

Heterogeneity in warm‐season (May–August) land‐atmosphere (LA) coupling is quantified with the long‐time, multiple‐station measurements from the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) program and the Moderate Resolution Imaging Spectroradiometer satellite remote sensing at the Southern Great Plains (SGP). We examine the coupling strength at seven additional locations with the same surface type (i.e., pasture/grassland) as the ARM SGP central facility (CF). To simultaneously consider multiple factors and consistently quantify their relative contributions, we apply a multiple linear regression method to correlate the surface evaporative fraction (EF) with near‐surface soil moisture (SM) and leaf area index (LAI). The observations show moderate to weak terrestrial segment LA coupling with large heterogeneity across the ARM SGP domain in warm season. Large spatial variabilities in the contributions from SM and LAI to the EF changes are also found. The coupling heterogeneities appear to be associated with differences in land use, anthropogenic activities, rooting depth, and soil type at different stations. Therefore, the complex LA interactions at the SGP cannot be well represented by those at the CF/E13 based on the metrics applied here. Overall, the LAI exerts more influence on the EF than does the SM due to its overwhelming impacts on the latent heat flux. This study complements previous studies based on measurements only from the CF and has important implications for modeling LA coupling in weather and climate models. The multiple linear regression provides a more comprehensive measure of the integrated impacts on LA coupling from several different factors.
Characterization of the Real Part of Dry Aerosol Refractive Index Over North America From the Surface to 12 km
Authors: Aldhaif Abdulmonam M. , Stahl Connor , Braun Rachel A. , Moghaddam Mohammad A. , Shingler Taylor , Crosbie Ewan , Sawamura Patricia , Dadashazar Hossein , Ziemba Luke , Jimenez Jose L. , Campuzano‐Jost Pedro , Sorooshian Armin
Published: July 2018

This study reports a characterization of the real part of dry particle refractive index (n) at 532 nm based on airborne measurements over the United States, Canada, the Pacific Ocean, and the Gulf of Mexico from the 2012 Deep Convective Clouds and Chemistry (DC3) and 2013 Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) campaigns. Effectivenvalues are reported, with the limitations and uncertainties discussed. Eight air mass types were identified based on criteria related to gas‐phase tracer concentrations, location, and altitude. Average values ofnfor these air types ranged from 1.50 to 1.53. Values ofnfor the organic aerosol (OA) fraction (nOA) were calculated using a linear mixing rule for each air mass type, with 1.52 shown to be a good approximation for all OA. Case studies detailing vertical structure revealed thatnandnOAincreased with altitude, simultaneous with enhancements in the mass fraction of OA. Values ofnOAwere positively (negatively) correlated with the O:C (H:C) ratio in the absence of biomass burning influence; in contrast, the cumulative data set revealed a slight decrease innOAas a function of the O:C ratio. The performance of parametric (multiple linear regression) and nonparametric (Gaussian process regression) methods in predictingnbased on aerosol composition data is discussed. It is shown that even small perturbations innvalues significantly impact aerosol optical depth retrievals, radiative forcing, and optical sizing instruments, emphasizing the importance of further improving the understanding of this important aerosol property.
Where Does Titan Sand Come From: Insight From Mechanical Properties of Titan Sand Candidates
Authors: Yu Xinting , Hörst Sarah M. , He Chao , McGuiggan Patricia , Crawford Bryan
Published: July 2018

Extensive equatorial linear dunes exist on Titan, but the origin of the sand, which appears to be organic, is unknown. We used nanoindentation to study the mechanical properties of a few Titan sand candidates, several natural sands on Earth, and common materials used in the Titan Wind Tunnel, to understand the mobility of Titan sand. We measured the elastic modulus (E), hardness (H), and fracture toughness (Kc) of these materials. Tholin's elastic modulus (10.4 ± 0.5 GPa) and hardness (0.53 ± 0.03 GPa) are both an order of magnitude smaller than silicate sand, and it is also smaller than the mechanically weak white gypsum sand. With a magnitude smaller fracture toughness (Kc = 0.036 ± 0.007 MPa·m1/2), tholin is also much more brittle than silicate sand. This indicates that Titan sand should be derived close to the equatorial regions where the current dunes are located, because tholin is too soft and brittle to be transported for long distances.
A Flexible and Efficient Radiation Scheme for the ECMWF Model
Authors: Hogan Robin J. , Bozzo Alessio
Published: July 2018

This paper describes a new radiation scheme ecRad for use both in the model of the European Centre for Medium‐Range Weather Forecasts (ECMWF), and off‐line for noncommercial research. Its modular structure allows the spectral resolution, the description of cloud and aerosol optical properties, and the solver, to be changed independently. The available solvers include the Monte Carlo Independent Column Approximation (McICA), Tripleclouds, and the Speedy Algorithm for Radiative Transfer through Cloud Sides (SPARTACUS), the latter which makes ECMWF the first global model capable of representing the 3‐D radiative effects of clouds. The new implementation of the operational McICA solver produces less noise in atmospheric heating rates, and is 41% faster, which can yield indirect forecast skill improvements via calling the radiation scheme more frequently. We demonstrate how longwave scattering may be implemented for clouds but not aerosols, which is only 4% more computationally costly overall than neglecting longwave scattering and yields further modest forecast improvements. It is also shown how a sequence of radiation changes in the last few years has led to a substantial reduction in stratospheric temperature biases.
Linking Paleogene Rifting and Inversion in the Northern Song Hong and Beibuwan Basins, Vietnam, With Left‐Lateral Motion on the Ailao Shan‐Red River Shear Zone
Authors: Fyhn Michael B. W. , Cuong Tong D. , Hoang Bui H. , Hovikoski Jussi , Olivarius Mette , Tuan Nguyen Q. , Tung Nguyen T. , Huyen Nguyen T. , Cuong Trinh X. , Nytoft Hans P. , Abatzis Ioannis , Nielsen Lars H.
Published: July 2018

Extrusion tectonics forced by plate collisions shape continents not only through lateral terrain displacement and mountain building but also through massive rifting and basin development. The rift system underneath the Gulf of Tonkin, Vietnam, constitutes a world‐class example of how extrusion tectonics drives continental rifting and transtensional basin development. Rifting and the Song Hong and Beibuwan Basin evolution are compared with the development of the Ailao Shan‐Red River Shear Zone (ASRRSZ) that accommodated the extrusion of Indochina forced by the Indian‐Eurasia collision. Rifting occurred during later Eocene‐Late Oligocene time forced by ASRRSZ left‐lateral shearing. Latest Oligocene‐earliest Miocene transpression and inversion brought rifting to a halt, after which left‐lateral shearing decreased. Paleogene rift systems extended along the trail of the ASRRSZ now outlined by lower to midcrustal metamorphic core complexes. Most of these rift systems were probably inverted and removed during the latest Oligocene‐earliest Miocene, however. The metamorphic core complexes are suggested to represent the lower to midcrustal roots of these transtensional rift basins exhumed by inversion. Rift termination in the northern Gulf of Tonkin and exhumation of the metamorphic core complexes coincided with cessation of Paleogene rifting along the western South China Sea, and a common causal mechanism is speculated.
Metagenomics reveals functional synergy and novel polysaccharide utilization loci in the Castor canadensis fecal microbiome
Authors: Armstrong Zachary , Mewis Keith , Liu Feng , Morgan-Lang Connor , Scofield Melanie , Durno Evan , Chen Hong Ming , Mehr Kevin , Withers Stephen G , Hallam Steven J
Published: July 2018

The North American beaver (Castor canadensis) has long been considered an engineering marvel, transforming landscapes and shaping biological diversity through its dam building behavior. While the beaver possesses conspicuous morphological features uniquely adapted for the use of woody plants as construction materials and dietary staples, relatively little is known about the specialized microorganisms inhabiting the beaver gastrointestinal tract and their functional roles in determining host nutrition. Here we use a combination of shotgun metagenomics, functional screening and carbohydrate biochemistry to chart the community structure and metabolic power of the beaver fecal microbiome. We relate this information to the metabolic capacity of other wood feeding and hindgut fermenting organisms and profile the functional repertoire of glycoside hydrolase (GH) families distributed among and between population genome bins. Metagenomic screening revealed novel mechanisms of xylan oligomer degradation involving GH43 enzymes from uncharacterized subfamilies and divergent polysaccharide utilization loci, indicating the potential for synergistic biomass deconstruction. Together, these results open a functional metagenomic window on less conspicuous adaptations enabling the beaver microbiome to efficiently convert woody plants into host nutrition and point toward rational design of enhanced enzyme mixtures for biorefining process streams.
On the decoupling of molecules at metal surfaces
Authors: Yang Xiaosheng , Krieger Ina , Lüftner Daniel , Weiß Simon , Heepenstrick Timo , Hollerer Michael , Hurdax Philipp , Koller Georg , Sokolowski Moritz , Puschnig Peter , Ramsey Michael G. , Tautz F. Stefan , Soubatch Serguei
Published: July 2018

Electronic surface hardening induced by oxygen atoms deposited on Cu(100) results in a true electronic and physical decoupling of adsorbed organic molecules.
A 1,2,3-triazolate lithium salt with ionic liquid properties at room temperature
Authors: Flachard D. , Rolland J. , Obadia M. M. , Serghei A. , Bouchet R. , Drockenmuller E.
Published: July 2018

A triethylene glycol-based 1,2,3-triazolate lithium salt with ionic liquid properties at room temperature is synthesized in three steps including copper-catalysed cycloaddition between alkyne-functionalized monomethoxy-triethylene glycol and azidomethyl pivalate, followed by the deprotection of the methyl pivalate group and further lithiation of the 1H-1,2,3-triazole intermediate.
Wet-chemical synthesized MCMB@Si@C microspheres for high-performance lithium-ion battery anodes
Authors: Lin Yangfan , Chen Yifan , Zhang Yaguang , Jiang Jingwei , He Yuanhong , Lei Yu , Du Ning , Yang Deren
Published: July 2018

MCMB@Si@C microspheres, in which silicon nanoparticles were closely connected with MCMB through strong chemical bonds, were synthesized as high-performance Li-ion battery anodes for the first time.
Wet chemical synthesis of metal oxide nanoparticles: a review
Authors: Nikam A. V. , Prasad B. L. V. , Kulkarni A. A.
Published: July 2018

Metal oxide nanoparticles are an important class of nanomaterials that have found several applications in science and technology.
Rational assembly of functional Co-MOFs via a mixed-ligand strategy: synthesis, structure, topological variation, photodegradation properties and dye adsorption
Authors: Fan Chuanbin , Zong Ziao , Zhang Xia , Xu Cungang , Zhu Zheng , Meng Xiangmin , Bi Shuangyu , Fan Yuhua
Published: July 2018

Four novel Co(ii) metal–organic frameworks were synthesized employing a rational design approach under solvothermal conditions.
In situ control of photochromic behavior through dual photo-isomerization using cobaloxime complexes with a spiropyran derivative and 2-cyanoethyl ligands
Authors: Sekine Akiko , Tanaka Masato , Uekusa Hidehiro , Yasuda Nobuhiro
Published: July 2018

The lifetime of colored species of spiropyran derivatives increased significantly after the 2-cyanoethyl group was photoisomerized to the 1-cyanoethyl group on exposure to visible light.
Mimetic biomineralization matrix using bacterial cellulose hydrogel and egg white to prepare various morphologies of CaCO3
Authors: Liu Xun , Zhou Yong , Pei Chonghua
Published: July 2018

A mimetic biomineralization matrix constructed from bacterial cellulose and egg white is used to prepare CaCO3 with various morphologies.
Self-healing and dewetting dynamics of a polymer nanofilm on a smooth substrate: strategies for dewetting suppression
Authors: Weng Yu-Hsuan , Tsao Heng-Kwong , Sheng Yu-Jane
Published: July 2018

The self-healing and dewetting dynamics of a polymer nanofilm on a smooth, partial wetting surface are explored by many-body dissipative particle dynamics.
Molecular structure, dynamics, and mechanical behavior of sodium aluminosilicate hydrate (NASH) gel at elevated temperature: a molecular dynamics study
Authors: Hou Dongshuai , Zhang Yu , Yang Tiejun , Zhang Jinrui , Pei Huafu , Zhang Jinglin , Jiang Jinyang , Li Tao
Published: July 2018

Elevated temperature weakens the aluminosilicate framework, resulting in the reduction in the tensile failure strength, but an increase in the toughness.
CO2interaction with violarite (FeNi2S4) surfaces: a dispersion-corrected DFT study
Authors: Posada-Pérez Sergio , Santos-Carballal David , Terranova Umberto , Roldan Alberto , Illas Francesc , de Leeuw Nora H.
Published: July 2018

The interaction between the CO2molecule and the violarite FeNi2S4{001} and {111} surfaces is studied using different exchange–correlation functionals and long-range dispersion correction approximations.
Neuroglobin is capable of self-oxidation of methionine64 introduced at the heme axial position
Authors: Liu Hai-Xiao , Li Lianzhi , He Bo , Gao Shu-Qin , Wen Ge-Bo , Lin Ying-Wu
Published: July 2018

The H64M neuroglobin mutant adopts a high-spin heme state and is capable of self-oxidation of the heme axial Met64, producing both methionine sulfoxide (SO-Met) and sulfone (SO2-Met), which represents the structure and function of cytochrome c in a non-native state.
Continuous electrochemical heat engines
Authors: Poletayev Andrey D. , McKay Ian S. , Chueh William C. , Majumdar Arun
Published: July 2018

Direct electrochemical heat engines enable the use of novel redox-active fluids and optimization of both power and efficiency for broad-spectrum heat harvesting.
Assessment of TEMPO as a thermally activatable base generator and its use in initiation of thermally-triggered thiol-Michael addition polymerizations
Authors: Zhang Xinpeng , Huang Sijia , Podgórski Maciej , Han Xun , Claudino Mauro , Bowman Christopher N.
Published: July 2018

We present a thermally initiated thiol-Michael reaction based on initiation via the temperature-dependent thiol-TEMPO oxidation–reduction reaction.
Patterns of reactions: a card sort task to investigate students’ organization of organic chemistry reactions
Authors: Galloway Kelli R. , Leung Min Wah , Flynn Alison B.
Published: July 2018

Research has shown that within a traditional organic chemistry curriculum, organic chemistry students struggle to develop deep conceptual understanding of reactions and attribute little meaning to the electron-pushing formalism. At the University of Ottawa, a new curriculum was developed for organic chemistry in which students are taught the language of the electron-pushing formalism prior to learning about specific reactions. Reactions are then organized by governing pattern of mechanism rather than by functional group and are taught in a gradient of complexity. To investigate how students are making connections across reactions within the new curriculum, a card sort task was developed. The card sort task consisted of 25 cards, each depicting the reactants and solvent for a reaction taught during the two-semester organic chemistry sequence. The first part of the task asked participants to sort 15 of 25 cards into categories. Then, participants were given the 10 remaining cards to incorporate into categories with the previous 15. Participants were asked to explain the characteristics of each category and their sorting process. Students (N= 16) in an organic chemistry course were interviewed while enrolled in the second semester course. We analyzed the students’ sorts based on which cards were sorted frequently together, the underlying characteristics used to form the categories, and the participants’ sorting processes. Participants created categories based on different levels of interpreting the reactions on the cards, with levels ranging from recognizing identical structural features to identifying similar types of mechanisms. Based on this study, if we want students to develop mechanistic thinking, we think students need to be more explicitly directed to the patterns present in organic reaction mechanisms and given opportunities to uncover and identify patterns on their own, during both summative and formative assessments.
Prussian blue decorated mesoporous silica hybrid nanocarriers for photoacoustic imaging-guided synergistic chemo-photothermal combination therapy
Authors: Santha Moorthy Madhappan , Hoang Giang , Subramanian Bharathiraja , Bui Nhat Quang , Panchanathan Manivasagan , Mondal Sudip , Thi Tuong Vy Phan , Kim Hyehyun , Oh Junghwan
Published: July 2018

Herein, Prussian blue decorated mesoporous silica PB@MSH-EDA NPs are fabricated for efficient photoacoustic imaging guided chemo-photothermal combination therapy.
First-principles study on the lattice plane and termination dependence of the electronic properties of the NiO/CH3NH3PbI3 interfaces
Authors: Li Longhua , Mi Jianli , Yong Yangchun , Mao Baodong , Shi Weidong
Published: July 2018

Density functional theory (DFT) and non-equilibrium Green's function (NEGF) calculations give an insight at an atomistic level into the structure–property relationship of the nickel oxide/organometal halide perovskite (NiO/MAPbI3) interface.
Active and reactive power sharing control strategy for VSGs in microgrid considering the different capacities of distributed energy resources
Authors: Altahir Sara Yahia , Yan Xiangwu , Gadalla Abuzaid Saeed
Published: July 2018

Since the concept that inverters can be controlled to behave like a synchronous generator has been proposed, the virtual synchronous generator (VSG) started to become the mainstream control of distributed energy resources connected distributed system. This concept simulates the frequency and voltage regulation of synchronous generator to improve the overall stability of the medium‐ and low‐voltage power system. Although significant research works have considered the application of VSGs in active and reactive power sharing, it seems to be that the issue of the proportional power sharing of VSGs of different capacities has not considered much in the previous works, especially when the distribution lines have increased resistive components. Such resistive disturbs the power flow and causes the power coupling. When focusing eyes on the parallel operation, VSGs need to coordinate parallel operation to increase the microgrid power quality, reliability, and for easy maintenance. Based on an improved droop control and virtual complex impedance, this study adjusts PI controller parameters to implement the proportional power sharing and decoupling for VSGs of different capacities. Simulation results are shown to verify the feasibility and validity of the control method.