bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ranking of critical species to preserve the functionality of mutualistic networks using thek-core decomposition
Authors: García-Algarra Javier , Pastor Juan Manuel , Iriondo José María , Galeano Javier 
Published: May 2017

BackgroundNetwork analysis has become a relevant approach to analyze cascading species extinctions resulting from perturbations on mutualistic interactions as a result of environmental change. In this context, it is essential to be able to point out key species, whose stability would prevent cascading extinctions, and the consequent loss of ecosystem function. In this study, we aim to explain how thek-core decomposition sheds light on the understanding the robustness of bipartite mutualistic networks.MethodsWe defined threek-magnitudes based on thek-core decomposition:k-radius,k-degree, andk-risk. The first one,k-radius, quantifies the distance from a node to the innermost shell of the partner guild, whilek-degree provides a measure of centrality in thek-shell based decomposition.k-risk is a way to measure the vulnerability of a network to the loss of a particular species. Using these magnitudes we analyzed 89 mutualistic networks involving plant pollinators or seed dispersers. Two static extinction procedures were implemented in whichk-degree andk-risk were compared against other commonly used ranking indexes, as for example MusRank, explained in detail in Material and Methods.ResultsWhen extinctions take place in both guilds,k-risk is the best ranking index if the goal is to identify the key species to preserve the giant component. When species are removed only in the primary class and cascading extinctions are measured in the secondary class, the most effective ranking index to identify the key species to preserve the giant component isk-degree. However, MusRank index was more effective when the goal is to identify the key species to preserve the greatest species richness in the second class.DiscussionThek-core decomposition offers a new topological view of the structure of mutualistic networks. The newk-radius,k-degree andk-risk magnitudes take advantage of its properties and provide new insight into the structure of mutualistic networks. Thek-risk andk-degree ranking indexes are especially effective approaches to identify key species to preserve when conservation practitioners focus on the preservation of ecosystem functionality over species richness.
Thermal convection as a possible mechanism for the origin of polygonal structures on Pluto's surface
Authors: Vilella Kenny , Deschamps Frédéric 
Published: May 2017

AbstractHigh‐resolution pictures of Pluto's surface obtained by the New Horizons spacecraft revealed, among other surface features, a large nitrogen ice glacier informally named Sputnik Planitia. The surface of this glacier is separated into a network of polygonal cells with a wavelength of ∼20–40 km. This network is similar to the convective patterns obtained under certain conditions by laboratory experiments, suggesting that it is the surface expression of thermal convection. Here we investigate the surface planform obtained for different convective systems in 3‐D Cartesian geometry with different modes of heating and rheologies. We find that bottom heated systems, as assumed by previous studies, do not produce surface planforms consistent with the observed pattern. Alternatively, for a certain range of Rayleigh‐Roberts number, RaH, a volumetrically heated system produces a surface planform similar to this pattern. We then combine scaling laws with values of RaH within its possible range to establish relationships between the critical parameters of Sputnik Planitia. In particular, our calculations indicate that the glacier thickness and the surface heat flux are in the ranges 2–10 km and 0.1–10 mW m−2, respectively. However, a difficulty is to identify a proper source of internal heating. We propose that the long‐term variations of surface temperature caused by variations in Pluto's orbit over millions of years produces secular cooling equivalent to internal heating. We find that this source of heating is sufficient to trigger thermal convection, but additional investigations are needed to determine under which conditions it can produce surface patterns similar to those of Sputnik Planitia.
Earth aeolian wind streaks: Comparison to wind data from model and stations
Authors: Cohen‐Zada A. L. , Maman S. , Blumberg D. G. 
Published: May 2017

AbstractWind streak is a collective term for a variety of aeolian features that display distinctive albedo surface patterns. Wind streaks have been used to map near‐surface winds and to estimate atmospheric circulation patterns on Mars and Venus. However, because wind streaks have been studied mostly on Mars and Venus, much of the knowledge regarding the mechanism and time frame of their formation and their relationship to the atmospheric circulation cannot be verified. This study aims to validate previous studies' results by a comparison of real and modeled wind data with wind streak orientations as measured from remote‐sensing images. Orientations of Earth wind streaks were statistically correlated to resultant drift direction (RDD) values calculated from reanalysis and wind data from 621 weather stations. The results showed good agreement between wind streak orientations and reanalysis RDD (r = 0.78). A moderate correlation was found between the wind streak orientations and the weather station data (r = 0.47); a similar trend was revealed on a regional scale when the analysis was performed by continent, with r ranging from 0.641 in North America to 0.922 in Antarctica. At sites where wind streak orientations did not correspond to the RDDs (i.e., a difference of 45°), seasonal and diurnal variations in the wind flow were found to be responsible for deviation from the global pattern. The study thus confirms that Earth wind streaks were formed by the present wind regime and they are indeed indicative of the long‐term prevailing wind direction on global and regional scales.
A quantitative method to the analysis of MLC leaf position and speed based on EPID and EBT3 film for dynamic IMRT treatment with different types of MLC
Authors: Li Yinghui , Chen Lixin , Zhu Jinhan , Wang Bin , Liu Xiaowei 
Published: May 2017

AbstractA quantitative method based on the electronic portal imaging system (EPID) and film was developed for MLC position and speed testing; this method was used for three MLC types (Millennium, MLCi, and Agility MLC). To determine the leaf position, a picket fence designed by the dynamic (DMLC) model was used. The full‐width half‐maximum (FWHM) values of each gap measured by EPID and EBT3 were converted to the gap width using the FWHM versus nominal gap width relationship. The algorithm developed for the picket fence analysis was able to quantify the gap width, the distance between gaps, and each individual leaf position. To determine the leaf speed, a 0.5 × 20 cm2 MLC‐defined sliding gap was applied across a 14 × 20 cm2 symmetry field. The linacs ran at a fixed‐dose rate. The use of different monitor units (MUs) for this test led to different leaf speeds. The effect of leaf transmission was considered in a speed accuracy analysis. The difference between the EPID and film results for the MLC position is less than 0.1 mm. For the three MLC types, twice the standard deviation (2 SD) is provided; 0.2, 0.4, and 0.4 mm for gap widths of three MLC types, and 0.1, 0.2, and 0.2 mm for distances between gaps. The individual leaf positions deviate from the preset positions within 0.1 mm. The variations in the speed profiles for the EPID and EBT3 results are consistent, but the EPID results are slightly better than the film results. Different speeds were measured for each MLC type. For all three MLC types, speed errors increase with increasing speed. The analysis speeds deviate from the preset speeds within approximately 0.01 cm s−1. This quantitative analysis of MLC position and speed provides an intuitive evaluation for MLC quality assurance (QA).
Effect of Deprotonation and Reduction on the Molecular Structure and Optical and Magnetic Properties of Metal‐Free Phthalocyanine (Pc): Comparison of H2Pc.− and HPc− Anions
Authors: Konarev Dmitri V. , Khasanov Salavat S. , Lyubovskaya Rimma N. 
Published: May 2017

AbstractA method for the selective preparation of mono‐deprotonated phthalocyanine (HPc− anions) was developed, enabling the synthesis of crystalline [(Na+)(2.2.2‐cryptand)][HPc−]⋅1.5 C6H4Cl2 (1). Salt 1 is isostructural to the salt obtained by reduction, [(Na+)(2.2.2‐cryptand)][H2Pc.−]⋅1.5 C6H4Cl2, containing the H2Pc.− radical anions. The phthalocyanine macrocycle in 1 shows no alternation of the C−N(imine) bonds that characterizes H2Pc.−. The spectrum of 1 does not feature near‐IR bands, and blueshifts of the Soret and Q bands characteristic of H2Pc.− were also not observed. Reduction shortens the N−H bonds, whereas deprotonation essentially elongates that bond with the remaining hydrogen atom. Deprotonated HPc− anions are EPR‐silent and diamagnetic, whereas H2Pc.− radical anions are paramagnetic and have the S=
spin state. These data indicate essential differences in the molecular structures as well as optical and magnetic properties of the deprotonated (HPc−) and reduced (H2Pc.−) phthalocyanine macrocycles.
Optochemische Steuerung biologischer Vorgänge in Zellen und Tieren
Authors: Ankenbruck Nicholas , Courtney Taylor , Naro Yuta , Deiters Alexander 
Published: May 2017

AbstractDie Regulation biologischer Vorgänge in der Natur unterliegt einer strengen räumlichen und zeitlichen Steuerung; eines der offensichtlichsten Beispiele ist die Embryogenese bei Metazoen. Zahlreiche chemische Werkzeuge wurden in der Zell‐ und Entwicklungsbiologie zur Untersuchung zellulärer Prozesse genutzt. Durch regelbare Steuerungsmethoden wurden die Anwendungsmöglichkeiten dieser Verfahren auch auf komplexe biologische Fragestellungen ausgeweitet. Licht eignet sich ausgezeichnet als externer Impuls, denn es kann mit sehr hoher räumlicher und zeitlicher Genauigkeit eingesetzt werden. Dazu wurden verschiedene optisch regulierte Werkzeuge entwickelt und auf lebende Systeme angewendet. In diesem Aufsatz diskutieren wir die aktuellen Entwicklungen optochemischer Werkzeuge, darunter niedermolekulare Verbindungen, Peptide, Proteine und Nukleinsäuren, die durch Lichteinstrahlung irreversibel oder reversibel kontrolliert werden können, insbesondere für Anwendungen in Zellen und in Tieren.
Der interstitiell gebundene Kohlenstoff der Nitrogenase ist deutlich stabiler als bisher angenommen
Authors: Grunenberg Jörg 
Published: May 2017

AbstractDie erste quantenmechanische Berechnung aller relevanten Potentialkonstanten (Compliance‐Konstanten) im Eisen‐Molybdän‐Cofaktor und Eisen‐Vanadium‐Cofaktor der Nitrogenase deutet darauf hin, dass das Kohlenstoffatom im Zentrum des Enzyms deutlich stärker gebunden ist als bisher angenommen wurde. Frühere Untersuchungen schienen mit einer schwachen Kraftkonstante (≈0.32 N cm−1) auf eine Platzhalterfunktion des interstitiellen Kohlenstoffs hinzudeuten. Dagegen bestätigen unsere Untersuchungen ein anderes Bild: Der zentrale Kohlenstoff fixiert den Eisen‐Schwefel‐Cluster deutlich durch sechs kovalente C‐Fe‐Bindungen. Mit einer quantenchemisch berechneten Potentialkonstante von über 1.3 N cm−1 scheint dieser auch dynamisch persistent. Nach unseren Untersuchungen müssen auch die Werte für die Festigkeit innerhalb des Eisen‐Schwefel‐Clusters nach oben korrigiert werden. Durch die Implementierung eines neuen Algorithmus in unser frei verfügbares Programm COMPLIANCE fällt in Zukunft die Koordinatenabhängigkeit bei der Berechnung von Hesse‐Matrizen weg. Die neu gewonnenen Informationen über die mechanochemischen Eigenschaften des FeMo‐Cofaktors werden in Zukunft bei der Aufklärung des Katalysezyklus der Stickstoff‐Fixierung von Bedeutung sein.
Quantifying Hydrogen‐Bond Populations in Dimethyl Sulfoxide/Water Mixtures
Authors: Oh Kwang‐Im , Rajesh Kavya , Stanton John F. , Baiz Carlos R. 
Published: May 2017

AbstractDimethyl sulfoxide (DMSO) disrupts the hydrogen‐bond networks in water. The widespread use of DMSO as a cosolvent, along with its unusual attributes, have inspired numerous studies. Herein, infrared absorption spectroscopy of the S=O stretching mode combined with molecular dynamics and quantum chemistry models were used to directly quantify DMSO/water hydrogen‐bond populations in binary mixtures. Singly H‐bonded species are dominant at 10 mol %, due to strong DMSO–water interactions. We found an unexpected increase in non‐hydrogen‐bonded DMSO near the eutectic point (ca. 35 mol %) which also correlates with several abnormalities in the bulk solution properties. We find evidence for three distinct regimes: 1) strong DMSO–water interactions (<30 mol %), 2) ideal‐solution‐like (30–90 mol %), and 3) self‐interaction, or aggregation, regime (>90 mol %). We propose a “step in” mechanism, which involves hydrogen bonding between water and the DMSO aggregate species.
A Nanojunction Polymer Photoelectrode for Efficient Charge Transport and Separation
Authors: Ruan Qiushi , Luo Wenjun , Xie Jijia , Wang Yiou , Liu Xu , Bai Zhiming , Carmalt Claire J. , Tang Junwang 
Published: May 2017

AbstractA metal‐free photoanode nanojunction architecture, composed of B‐doped carbon nitride nanolayer and bulk carbon nitride, was fabricated by a one‐step approach. This type of nanojunction (s‐BCN) overcomes a few intrinsic drawbacks of carbon nitride film (severe bulk charge recombination and slow charge transfer). The top layer of the nanojunction has a depth of ca. 100 nm and the bottom layer is ca. 900 nm. The nanojunction photoanode results into a 10‐fold higher photocurrent than bulk graphitic carbon nitride (G‐CN) photoanode, with a record photocurrent density of 103.2 μA cm−2 at 1.23 V vs. RHE under one sun irradiation and an extremely high incident photon‐to‐current efficiency (IPCE) of ca. 10 % at 400 nm. Electrochemical impedance spectroscopy, Mott–Schottky plots, and intensity‐modulated photocurrent spectroscopy show that such enhancement is mainly due to the mitigated deep trap states, a more than 10 times faster charge transfer rate and nearly three times higher conductivity due to the nanojunction architecture.
On‐the‐Fly and Incremental Technique for Fault Diagnosis of Discrete Event Systems Modeled by Labeled Petri Nets
Authors: Liu Baisi , Ghazel Mohamed , Toguyéni Armand 
Published: May 2017

AbstractIn this paper, we develop an on‐the‐fly and incremental technique for fault diagnosis of discrete event systems modeled by labeled Petri nets, in order to tackle the combinatorial explosion problem. K‐diagnosability, diagnosability, Kmin (the minimum K ensuring diagnosability) and on‐line diagnosis are solved on the basis of the on‐the‐fly and incremental building of two structures, called respectively fault marking graph and fault marking set graph, in parallel. We build on existing results, namely those establishing necessary and sufficient conditions for diagnosability, but we bring mechanisms to make the checking of such conditions potentially more efficient. We show that, in general, analyzing or even building the whole reachability graph is unnecessary to analyze diagnosability and build an on‐line diagnoser. Our technique was implemented in a prototype tool called OF‐PENDA, and a railway level crossing benchmark is used to make a comparative discussion pertaining to efficiency in terms of time and memory relative to some existing approaches.
Spectrofluorometric determination of clonazepam in dosage forms: Application to content uniformity testing and human plasma
Authors: Belal Fathalla , Ibrahim Fawzia , Sheribah Zainab , Alaa Heba 
Published: May 2017

AbstractThe present paper describes a developed and validated simple, highly sensitive and cost‐effective spectrofluorometric method for determination of clonazepam (CNP). The proposed method depends on forming a highly fluorescent product through the reduction of CNP with Zn/HCl. The produced fluorophore exhibits a strong fluorescence at λem 350 nm after excitation at λex 250 nm. The use of carboxymethylcellulose (CMC) greatly enhanced the fluorescence intensity of the produced fluorophore to the extent of about 100%. Calibration curve showed good linear regression (r2 > 0.9998) within test ranges of 20–400 ng ml−1 with a lower detection limit of 0.67 ng ml−1 and lower quantification limit of 2.22 ng ml−1 upon using CMC. The method was successfully applied to the analysis of CNP in its pharmaceutical formulations and the results were in agreement with those obtained using a reference method. Furthermore, the content uniformity testing of the tablets was also performed. The application of the proposed method was extended to determine CNP in spiked human plasma sample as a preliminary investigation and the results were satisfactory.
Coherence of BOLD signal and electrical activity in the human brain during deep sevoflurane anesthesia
Authors: Golkowski Daniel , Ranft Andreas , Kiel Tobias , Riedl Valentin , Kohl Philipp , Rohrer Guido , Pientka Joachim , Berger Sebastian , Preibisch Christine , Zimmer Claus , Mashour George A. , Schneider Gerhard , Kochs Eberhard F. , Ilg Rüdiger , Jordan Denis 
Published: May 2017

AbstractIntroductionChanges in neural activity induce changes in functional magnetic resonance (fMRI) blood oxygenation level dependent (BOLD) signal. Commonly, increases in BOLD signal are ascribed to cellular excitation.ObjectiveThe relationship between electrical activity and BOLD signal in the human brain was probed on the basis of burst suppression EEG. This condition includes two distinct states of high and low electrical activity.MethodsResting‐state simultaneous EEG and BOLD measurements were acquired during deep sevoflurane anesthesia with burst suppression EEG in nineteen healthy volunteers. Afterwards, fMRI volumes were assigned to one of the two states (burst or suppression) as defined by the EEG.ResultsIn the frontal, parietal and temporal lobes as well as in the basal ganglia, BOLD signal increased after burst onset in the EEG and decreased after onset of EEG suppression. In contrast, BOLD signal in the occipital lobe was anticorrelated to electrical activity. This finding was obtained consistently in a general linear model and in raw data.ConclusionsIn human brains exhibiting burst suppression EEG induced by sevoflurane, the positive correlation between BOLD signal and electrical brain activity could be confirmed in most gray matter. The exceptional behavior of the occipital lobe with an anticorrelation of BOLD signal and electrical activity might be due to specific neurovascular coupling mechanisms that are pronounced in the deeply anesthetized brain.
A dynamic approach for teaching algorithms: Integrating immersive environments and virtual learning environments
Authors: Nunes Felipe B. , Herpich Fabrício , Do Amaral Érico M. H. , Voss Gleizer B. , Zunguze Manuel C. , Medina Roseclea D. , Tarouco Liane M. R. 
Published: May 2017

AbstractUtilization of technology in education lead to important changes in methods and techniques, where the use of virtual learning environments and virtual worlds provided a solution of a rich simulation and with a high level of interactivity and immersion. This article provides a summary of a research that searches integrate two different technologies [VLE and VW], by means of a solution called Sloodle. The main focus is demystify the use of this solution, introducing the mainly characteristics involved in the process of installation and insertion of this resources and evaluate the effectiveness of these resources as supporting tools in the teaching of algorithms in Computer Engineering course. The applications used in this research were OpenSimulator as Virtual World; Moodle as VLE; the online software IDEOne for the algorithm exposure and Sloodle. Analysis confirms that the utilization of virtual world combined with Moodle using Sloodle, it is a valid alternative to the process of teaching and learning, motivating the students and stimulating the feeling of immersion during the performance of activities. It allows identifying the difficulties to be overcome in this type of solution, like the utilization of Sloodle and technology limitations of their resources.
Catalytic Hydrolysis of Polysaccharides Derived from Fast‐Growing Green Macroalgae
Authors: Onda Ayumu , Onda Sayuri , Koike Miyuki , Yanagisawa Kazumichi , Tsubaki Shuntaro , Hiraoka Masanori 
Published: May 2017

AbstractGreen macroalgae, such as Ulva spp., has a higher growth rate than terrestrial lingocellulosic biomass, which often leads to serious environmental issues such as green tide. So, it is a promising feedstock for biorefineries. Hiraoka produced Ulva with reproducible compositions and sizes by our original cultivation method. The macroalgae contained approximately 35 wt % of a soluble polysaccharide called ulvan, which is a sulfated glucuronorhamnan polysaccharide. The catalytic conversion of extracted ulvan was performed under hydrothermal conditions at 130 °C by using solid acid catalysts. The Amberlyst 70 catalyst has a stable structure and gave monosaccharides in quantitative yield, predominantly in the form of rhamnose. The Amberlyst 70 catalyst showed higher activity than sulfonated activated‐carbon (AC‐SO3H) in the hydrothermal conversion of ulvan, although Amberlyst 70 showed lower catalytic activity than AC‐SO3H in the hydrolysis of starch.
A Mesoporous Cobalt Aluminate Spinel Catalyst for Nonoxidative Propane Dehydrogenation
Authors: Hu Bo , Kim Wun‐Gwi , Sulmonetti Taylor P. , Sarazen Michele L. , Tan Shuai , So Jungseob , Liu Yujun , Dixit Ravindra S. , Nair Sankar , Jones Christopher W. 
Published: May 2017

AbstractA mesoporous CoAl2O4 spinel (Co‐Al) is synthesized by a one‐step evaporation‐induced self‐assembly (EISA) method. N2 physisorption and TEM are used to demonstrate the presence of mesopores within the Co‐Al material. The spinel crystal structure of Co‐Al, in which Co occupies tetrahedral (Td) sites, is confirmed by using XRD and UV/Vis spectroscopy. In nonoxidative propane dehydrogenation at 550 °C, a propane conversion of approximately 8 % is observed for Co‐Al with a >80 % propylene selectivity, which corresponds to a turnover frequency of 5.1 h−1 based on an estimation of the number of active Co sites by using NH3 temperature‐programmed desorption. A much higher propane conversion rate and a circa 80 % propylene selectivity is observed upon reaction at 600 °C. Continuous deactivation of the catalyst is observed for Co‐Al at this elevated temperature. In situ X‐ray absorption spectroscopy results suggest that Co remains as a Td Co2+ species under the reaction conditions. The Td Co2+ sites within the Co‐Al material are thus proposed to act as Lewis acidic active sites; this acidity is verified using IR spectroscopy with pyridine as a probe molecule.