bluuebunny/crossref_metadata_2025 huggingface dataset:
Defining Extreme Events: A Cross‐Disciplinary Review
Authors: McPhillips Lauren E. , Chang Heejun , Chester Mikhail V. , Depietri Yaella , Friedman Erin , Grimm Nancy B. , Kominoski John S. , McPhearson Timon , Méndez‐Lázaro Pablo , Rosi Emma J. , Shafiei Shiva Javad
Published: February 2018

Extreme events are of interest worldwide given their potential for substantial impacts on social, ecological, and technical systems. Many climate‐related extreme events are increasing in frequency and/or magnitude due to anthropogenic climate change, and there is increased potential for impacts due to the location of urbanization and the expansion of urban centers and infrastructures. Many disciplines are engaged in research and management of these events. However, a lack of coherence exists in what constitutes and defines an extreme event across these fields, which impedes our ability to holistically understand and manage these events. Here, we review 10 years of academic literature and use text analysis to elucidate how six major disciplines—climatology, earth sciences, ecology, engineering, hydrology, and social sciences—define and communicate extreme events. Our results highlight critical disciplinary differences in the language used to communicate extreme events. Additionally, we found a wide range in definitions and thresholds, with more than half of examined papers not providing an explicit definition, and disagreement over whether impacts are included in the definition. We urge distinction between extreme events and their impacts, so that we can better assess when responses to extreme events have actually enhanced resilience. Additionally, we suggest that all researchers and managers of extreme events be more explicit in their definition of such events as well as be more cognizant of how they are communicating extreme events. We believe clearer and more consistent definitions and communication can support transdisciplinary understanding and management of extreme events.
Satellite Chlorophyll Fluorescence and Soil Moisture Observations Lead to Advances in the Predictive Understanding of Global Terrestrial Coupled Carbon‐Water Cycles
Authors: Qiu Bo , Xue Yongkang , Fisher Joshua B. , Guo Weidong , Berry Joseph A. , Zhang Yongguang
Published: February 2018

The terrestrial carbon and water cycles are coupled through a multitude of connected processes among soil, roots, leaves, and the atmosphere. The strength and sensitivity of these couplings are not yet well known at the global scale, which contributes to uncertainty in predicting the terrestrial water and carbon budgets. We now have synchronous, global‐scale satellite observations of critical terrestrial carbon and water cycle components: solar‐induced chlorophyll fluorescence (SIF) and soil moisture. We used these observations within the framework of a global terrestrial biosphere model (Simplified Simple Biosphere Model version 2.0, SSiB2) to investigate carbon‐water coupling processes. We updated SSiB2 to include a mechanistic representation of SIF and tested the sensitivity of model parameters to improve the simulation of both SIF and soil moisture with the ultimate objective of improving the first‐order terrestrial carbon component, gross primary production. Although several vegetation parameters, such as leaf area index and the green leaf fraction, improved the simulated SIF, and several soil parameters, such as hydraulic conductivity, improved simulated soil moisture, their effects were mainly limited to their respective cycles. One root‐mean‐square error parameter emerged as the key coupler between the carbon and water cycles: the wilting point. Updates to the wilting point significantly improved the simulations for SIF and gross primary production although substantial mismatches with the satellite data still existed. This study demonstrates the value of synchronous global measurements of the terrestrial carbon and water cycles in improving the understanding of coupled carbon‐water cycles.
Implementing Dynamic Root Optimization in Noah‐MP for Simulating Phreatophytic Root Water Uptake
Authors: Wang Ping , Niu Guo‐Yue , Fang Yuan‐Hao , Wu Run‐Jian , Yu Jing‐Jie , Yuan Guo‐Fu , Pozdniakov Sergey P. , Scott Russell L.
Published: February 2018

Widely distributed in arid and semiarid regions, phreatophytic roots extend into the saturated zone and extract water directly from groundwater. In this paper, we implemented a vegetation optimality model of root dynamics (VOM‐ROOT) in the Noah land surface model with multiparameterization options (Noah‐MP LSM) to model the extraction of groundwater through phreatophytic roots at a riparian site with a hyperarid climate (with precipitation of 35 mm/yr) in northwestern China. VOM‐ROOT numerically describes the natural optimization of the root profile in response to changes in subsurface water conditions. The coupled Noah‐MP/VOM‐ROOT model substantially improves the simulation of surface energy and water fluxes, particularly during the growing season, compared to the prescribed static root profile in the default Noah‐MP. In the coupled model, more roots are required to grow into the saturated zone to meet transpiration demand when the groundwater level declines over the growing season. The modeling results indicate that at the study site, the modeled annual transpiration is 472 mm, accounting for 92.3% of the total evapotranspiration. Direct root water uptake from the capillary fringe and groundwater, which is supplied by lateral groundwater flow, accounts for approximately 84% of the total transpiration. This study demonstrates the importance of implementing a dynamic root scheme in a land surface model for adequately simulating phreatophytic root water uptake and the associated latent heat flux.
Permeability Sensitivity Functions and Rapid Simulation of Hydraulic‐Testing Measurements Using Perturbation Theory
Authors: Escobar Gómez J. D. , Torres‐Verdín C.
Published: February 2018

Single‐well pressure‐diffusion simulators enable improved quantitative understanding of hydraulic‐testing measurements in the presence of arbitrary spatial variations of rock properties. Simulators of this type implement robust numerical algorithms which are often computationally expensive, thereby making the solution of the forward modeling problem onerous and inefficient. We introduce a time‐domain perturbation theory for anisotropic permeable media to efficiently and accurately approximate the transient pressure response of spatially complex aquifers. Although theoretically valid for any spatially dependent rock/fluid property, our single‐phase flow study emphasizes arbitrary spatial variations of permeability and anisotropy, which constitute key objectives of hydraulic‐testing operations. Contrary to time‐honored techniques, the perturbation method invokes pressure‐flow deconvolution to compute the background medium's permeability sensitivity function (PSF) with a single numerical simulation run. Subsequently, the first‐order term of the perturbed solution is obtained by solving an integral equation that weighs the spatial variations of permeability with the spatial‐dependent and time‐dependent PSF. Finally, discrete convolution transforms the constant‐flow approximation to arbitrary multirate conditions. Multidimensional numerical simulation studies for a wide range of single‐well field conditions indicate that perturbed solutions can be computed in less than a few CPU seconds with relative errors in pressure of
5%, corresponding to perturbations in background permeability of up to two orders of magnitude. Our work confirms that the proposed joint perturbation‐convolution (JPC) method is an efficient alternative to analytical and numerical solutions for accurate modeling of pressure‐diffusion phenomena induced by Neumann or Dirichlet boundary conditions.
Spatial Patterns of Development Drive Water Use
Authors: Sanchez G. M. , Smith J. W. , Terando A. , Sun G. , Meentemeyer R. K.
Published: February 2018

Water availability is becoming more uncertain as human populations grow, cities expand into rural regions and the climate changes. In this study, we examine the functional relationship between water use and the spatial patterns of developed land across the rapidly growing region of the southeastern United States. We quantified the spatial pattern of developed land within census tract boundaries, including multiple metrics of density and configuration. Through non‐spatial and spatial regression approaches we examined relationships and spatial dependencies between the spatial pattern metrics, socio‐economic and environmental variables and two water use variables: a) domestic water use, and b) total development‐related water use (a combination of public supply, domestic self‐supply and industrial self‐supply). Metrics describing the spatial patterns of development had the highest measure of relative importance (accounting for 53% of model's explanatory power), explaining significantly more variance in water use compared to socio‐economic or environmental variables commonly used to estimate water use. Integrating metrics characterizing the spatial pattern of development into water use models is likely to increase their utility and could facilitate water‐efficient land use planning.
Areally Extensive Surface Bedrock Exposures on Mars: Many Are Clastic Rocks, Not Lavas
Authors: Rogers A. Deanne , Warner Nicholas H. , Golombek Matthew P. , Head James W. , Cowart Justin C.
Published: February 2018

Areally extensive exposures of intact olivine/pyroxene‐enriched rock, as well as feldspar‐enriched rock, are found in isolated locations throughout the Martian highlands. The petrogenetic origin(s) of these rock units are not well understood, but some previous studies favored an effusive volcanic origin partly on the basis of distinctive composition and relatively high thermal inertia. Here we show that the regolith development, crater retention, and morphological characteristics for many of these “bedrock plains” are not consistent with competent lavas and reinterpret the high thermal inertia orbital signatures to represent friable materials that are more easily kept free of comminution products through eolian activity. Candidate origins include pyroclastic rocks, impact‐generated materials, or detrital sedimentary rocks. Olivine/pyroxene enrichments in bedrock plains relative to surrounding materials could have potentially formed through deflation and preferential removal of plagioclase.
Measuring Carbon Monoxide With TROPOMI: First Results and a Comparison With ECMWF‐IFS Analysis Data
Authors: Borsdorff T. , Aan de Brugh J. , Hu H. , Aben I. , Hasekamp O. , Landgraf J.
Published: February 2018

The Tropospheric Monitoring Instrument (TROPOMI) was launched onboard of the European Space Agency's (ESA) Sentinel‐5P satellite. One of the mission's key products is the total column density of carbon monoxide, inferred from TROPOMI's 2.3 μm measurements. Using the operational processing algorithm, we analyze six subsequent days of measurements during the commissioning phase. The TROPOMI product is compared with CO fields from the European Centre for Medium‐Range Weather Forecasts (ECMWF) assimilation system. Globally, a small mean difference between the data sets of 3.2 ± 5.5% with a correlation coefficient of 0.97 is found. The daily global coverage of TROPOMI enables it to capture day‐to‐day evolution of the atmospheric composition. As an example, we discuss the air pollution event of India in November 2017 with high carbon monoxide (CO) concentrations, which partly dispersed when the CO polluted air was transported north alongside the Himalaya to China. The striking agreement and also regional differences with ECMWF indicate new exciting applications for the TROPOMI CO data product.
Social influence in investigative interviews: The effects of reciprocity
Authors: Matsumoto David , Hwang Hyisung C.
Published: February 2018

This study examined how a principle of social influence—reciprocity—affects the informational elements produced in an investigative interview. Participants from 3 ethnic/cultural groups recruited from the community either received a bottle of water or not prior to their engaging in an investigative interview, in which they either told the truth or lied about having committed a mock crime. Three different informational elements (Relevant details, Irrelevant details, and Plausibility) were coded from their responses, and rapport in the interaction was coded from video. Offering water facilitated greater rapport and influenced the informational elements. These effects were moderated by Veracity condition: For liars, offering water produced more Relevant details and greater Plausibility in the statements and this effect was mediated by rapport. Ethnicity/culture did not moderate these findings. These findings suggested the applicability of principles of social influence in investigative interviews across cultures/ethnicities and had theoretical, empirical, and practical implications.
Can reading time predict mind wandering in expository text?
Authors: Naylor Jamie S. , Sanchez Christopher A.
Published: February 2018

Prior research has suggested that episodes of mind wandering not only negatively impact text comprehension but also are associated with fluctuations in reading behavior. However, these studies typically do not account for differences in the fundamental nature of the text itself, namely, whether it is narrative or expository in structure. As much research has supported the idea that these text genres are processed differently, it is of interest to determine whether similar changes in reading patterns are observed when mind wandering in an expository text. The present study examined whether fluctuations in sentence‐by‐sentence reading times were associated with periods of mindless reading during processing of an expository text. Results indicated that although mindless reading did negatively impact learning, probed reading time did not vary as a function of mind wandering. These results suggest that research aimed at studying mind wandering while reading may need to account for text genre.
No Lake Wobegon in Beijing? The impact of culture on the perception of relative ranking
Authors: Wu Shali
Published: February 2018

A prominent example in the literature on relative ranking is the “better‐than‐average” effect: that people have a general tendency to view themselves in a positive light and think they are above average. The current paper evaluates whether such biases are specific to culture. In Experiment 1, Americans exhibited a larger better‐than‐average effect than Chinese. In Experiment 2, the study was designed to understand what drives this cultural difference. Estimates of relative standing for Americans relied more on perceptions of their own ability compared to those for Chinese participants. Relatively structured questions (experimental manipulation of the question frame) facilitate Americans making better judgments but not Chinese, supporting the hypothesis that relative‐ranking estimates are influenced by the degree to which other (vs. self) information is used cross‐culturally.
Metallurgical Strategies for the Joining of Titanium Alloys with Steels
Authors: Tomashchuk Iryna , Sallamand Pierre
Published: February 2018

Welding of titanium alloys with steels presents a high risk of cold cracking because of the formation of extremely brittle intermetallic phases associated with residual stress. The use of solid state and diffusion‐based methods as well as a high power beam welding allow so far to achieve good tensile properties through the control of a local phase content. This review summarizes existing approaches for the creation of defect‐free joints between titanium alloys and steels: direct joining without a filler material, the use of insert having full metallurgical compatibility with titanium, the use of insert compatible with stainless steel, and multilayer engineering.
Highly Stable Plasmon Induced Hot Hole Transfer into Silicon via a SrTiO3 Passivation Interface
Authors: Matsui Takayuki , Li Yi , Hsu Min‐Hsiang Mark , Merckling Clement , Oulton Rupert F. , Cohen Lesley F. , Maier Stefan A.
Published: February 2018

Extracting plasmon‐induced hot carriers over a metal–semiconductor Schottky barrier enables photodetection below the semiconductor bandgap energy. However, interfacial carrier recombination hinders the efficiency and stability of this process, severely limiting its implementation in telecommunication. This study proposes and demonstrates the use of epitaxially grown lattice‐matched SrTiO3 for interfacial passivation of silicon‐based plasmonic Schottky devices. The devices are activated by an electrical soft‐breakdown of the interfacial SrTiO3 layer, resulting in reproducible rectified Schottky characteristics. The transition to a low resistance state of the SrTiO3 layer boosts the extraction efficiency of hot holes upon resonant plasmonic excitation, giving rise to a two orders of magnitude higher photocurrent compared to devices with a native oxide layer. Photoresponse, tunability, and barrier height studies under reverse biases as high as 100 V present superior stability with the incorporation of the SrTiO3 layer. The investigation paves the way toward plasmon‐induced photodetection for practical applications including those under challenging operating conditions.
Scalable and Highly Efficient Mesoporous Wood‐Based Solar Steam Generation Device: Localized Heat, Rapid Water Transport
Authors: Li Tian , Liu He , Zhao Xinpeng , Chen Guang , Dai Jiaqi , Pastel Glenn , Jia Chao , Chen Chaoji , Hitz Emily , Siddhartha Das , Yang Ronggui , Hu Liangbing
Published: February 2018

Solar steam generation is regarded as one of the most sustainable techniques for desalination and wastewater treatment. However, there has been a lack of scalable material systems with high efficiency under 1 Sun. A solar steam generation device is designed utilizing crossplane water transport in wood via nanoscale channels and the preferred thermal transport direction is decoupled to reduce the conductive heat loss. A high steam generation efficiency of 80% under 1 Sun and 89% under 10 Suns is achieved. Surprisingly, the crossplanes perpendicular to the mesoporous wood can provide rapid water transport via the pits and spirals. The cellulose nanofibers are circularly oriented around the pits and highly aligned along spirals to draw water across lumens. Meanwhile, the anisotropic thermal conduction of mesoporous wood is utilized, which can provide better insulation than widely used super‐thermal insulator Styrofoam (≈0.03 W m−1 K−1). The crossplane direction of wood exhibits a thermal conductivity of 0.11 W m−1 K−1. The anisotropic thermal conduction redirects the absorbed heat along the in‐plane direction while impeding the conductive heat loss to the water. The solar steam generation device is promising for cost‐effective and large‐scale application under ambient solar irradiance.
Tumor‐Specific Self‐Degradable Nanogels as Potential Carriers for Systemic Delivery of Anticancer Proteins
Authors: Zhu Qiuwen , Chen Xiaojie , Xu Xiao , Zhang Ying , Zhang Can , Mo Ran
Published: February 2018

Development of a safe and effective carrier for systemic protein delivery is highly desirable, which depends on management of the relationship among loading capacity, stability, delivery efficiency, and degradability. Here, a tumor‐specific self‐degradable nanogel composed of hyaluronidase (HAase)‐degradable hyaluronic acid (HA) matrices entrapping acid‐activatable HAase (aHAase) for systemic delivery of anticancer proteins is reported. Collaboratively crosslinked nanogels (cNG) obtained by the synthetic cholesteryl methacrylated HA show high protein‐loading capacity and stability. The aHAase is engineered by modifying the HAase with citraconic anhydride to shield its HA‐degrading activity, which can be reversibly activated by hydrolysis of the citraconic amide under acidic condition. In the tumor microenvironment, the mild acidity activates the aHAase partially, which results in swelling of the cNG and releasing of the aHAase. The released reactivated aHAase can degrade the HA that is also a major constituent of tumor extracellular matrix to increase perfusion of the cNG in the tumor stroma. In the acidic endocytic vesicles, the aHAase is fully reactivated. The active aHAase completely degrades the cNG to release the encapsulated anticancer protein, deoxyribonuclease I intracellularly, which digests the DNA to cause tumor cell death for enhanced antitumor efficacy.
Ultrasensitive and Stable Au Dimer‐Based Colorimetric Sensors Using the Dynamically Tunable Gap‐Dependent Plasmonic Coupling Optical Properties
Authors: Liu Dilong , Fang Lingling , Zhou Fei , Li Huilin , Zhang Tao , Li Cuncheng , Cai Weiping , Deng Zhaoxiang , Li Liangbin , Li Yue
Published: February 2018

A novel Au dimer‐based colorimetric sensor is reported that consists of Au dimers to a chitosan hydrogel film. It utilizes the ultrasensitively gap‐dependent properties of plasmonic coupling (PC) peak shift, which is associated with the dynamical tuning of the interparticle gap of the Au dimer driven by the volume swelling of the chitosan hydrogel film. The interparticle gap and PC peak shift of the Au dimer can be precisely and extensively controlled through the pH‐driven volume change of chitosan hydrogel film. This colorimetric sensor exhibits a high optical sensitivity and stability, and it works in a completely reversible manner at high pH values. Importantly, the sensitivity of the composite film can be tuned by controlling the crosslinking time of the composite film, and thus leading to a wide dynamic tuning sensitive range for different applications. This presented strategy paves a way to achieve the construction of high‐quality colorimetric sensors with ultrahigh sensitivity, stability and wide dynamic tuning sensitive range.
Direct Visualization of the Reversible O2−/O− Redox Process in Li‐Rich Cathode Materials
Authors: Li Xiang , Qiao Yu , Guo Shaohua , Xu Zhenming , Zhu Hong , Zhang Xiaoyu , Yuan Yang , He Ping , Ishida Masayoshi , Zhou Haoshen
Published: February 2018

Conventional cathodes of Li‐ion batteries mainly operate through an insertion–extraction process involving transition metal redox. These cathodes will not be able to meet the increasing requirements until lithium‐rich layered oxides emerge with beyond‐capacity performance. Nevertheless, in‐depth understanding of the evolution of crystal and excess capacity delivered by Li‐rich layered oxides is insufficient. Herein, various in situ technologies such as X‐ray diffraction and Raman spectroscopy are employed for a typical material Li1.2Ni0.2Mn0.6O2, directly visualizing O−O− (peroxo oxygen dimers) bonding mostly along the c‐axis and demonstrating the reversible O2−/O− redox process. Additionally, the formation of the peroxo OO bond is calculated via density functional theory, and the corresponding OO bond length of ≈1.3 Å matches well with the in situ Raman results. These findings enrich the oxygen chemistry in layered oxides and open opportunities to design high‐performance positive electrodes for lithium‐ion batteries.
Synthesis of Spirofurooxindoles via Phenyliodine(III) Bis(trifluoroacetate) (PIFA)‐Mediated Cascade Oxidative C−O and C−C Bond Formation
Authors: Sun Desong , Zhao Xiaoyuan , Zhang Bobo , Cong Ying , Wan Xintong , Bao Mingmai , Zhao Xue , Li Bing , Zhang‐Negrerie Daisy , Du Yunfei
Published: February 2018

Upon treatment with solely a hypervalent iodine reagent of phenyliodine(III) bis(trifluoroacetate) (PIFA), 3‐(2‐hydroxyphenyl)‐3‐oxo‐N‐phenyl propanamides and a series of its derivatives were conveniently converted to a class of undocumented spirofurooxindoles under mild conditions. Control experiments provided evidence that this spirocyclization process encompassed a cascade oxidative reactions involving the formation of a C−O bond prior to that of C−C bond.

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Transition‐Metal‐Free Cross‐Dehydrogenative Coupling of Ethyl Arylacetates with Benzoic/Cinnamic Acids: A Practical Synthesis of α‐Acyloxy Esters
Authors: Sharma Anup Kumar , Kumar Promod , Vishwakarma Ramesh Kumar , Singh Krishna Nand
Published: February 2018

An efficient cross‐dehydrogenative coupling of benzylic C(sp3)−H of ethyl arylacetates with benzoic/cinnamic acids has been developed to afford α‐acyloxy esters in reasonably high yields under environmentally benign conditions.
Hand preference on unimanual and bimanual tasks in Barbary macaques (Macaca sylvanus)
Authors: Regaiolli Barbara , Spiezio Caterina , Hopkins William D.
Published: February 2018

The presence of group‐level handedness in non‐human primates remains controversial, as different studies have produced inconsistent results. Bimanual coordinated tasks have been found to elicit more pronounced hand preferences than simple unimanual tasks. The aim of this study was to examine manual lateralization in a group of 15 Barbary macaques during unimanual and bimanual tasks. In the unimanual task, data on simple food reaching in a foraging context were collected. During the bimanual task, macaques had to use one hand to hold a tube‐shaped apparatus while reaching with the other hand to retrieve the food inside it. Data on the hand use to retrieve food were collected. First, no significant group‐level hand preference was found for the unimanual task. However, a significant right hand bias was evident for the bimanual task. At the individual‐level, approximately 47% and 67% of the subjects had a significant hand preference in the unimanual and bimanual task respectively. The strength of the hand preference was greater in the bimanual than in the unimanual task. Findings of this study add Macaca sylvanus to the other species showing a right hand preference for coordinated bimanual tasks. Moreover, our results add to the growing body of evidence that bimanual tasks are more suitable and valid measures to investigate handedness in non‐human primates.
Odorant Receptor 7D4 Activation Dynamics
Authors: de March Claire A. , Topin Jérémie , Bruguera Elise , Novikov Gleb , Ikegami Kentaro , Matsunami Hiroaki , Golebiowski Jérôme
Published: February 2018

Deciphering how an odorant activates an odorant receptor (OR) and how changes in specific OR residues affect its responsiveness are central to understanding our sense of smell. A joint approach combining site‐directed mutagenesis and functional assays with computational modeling has been used to explore the signaling mechanics of OR7D4. In this OR, a genetic polymorphism affects our perception of androstenone. Molecular simulations totaling 0.12 ms predicted that, similarly to observations for other G‐protein‐coupled receptors with known experimental structures, an activation pathway connects the ligand and the G‐protein binding site. The 3D model activation mechanism correlates with in vitro data and notably predicts that the OR7D4 WM variant is not activated. Upon activation, an OR‐specific sequence motif is the convergence point of the mechanism. Our study suggests that robust homology modeling can serve as a powerful tool to capture OR dynamics related to smell perception.
Bestimmung der Verknüpfungspunkte in fluoreszenten Polymernetzwerken
Authors: Estupiñán Diego , Barner‐Kowollik Christopher , Barner Leonie
Published: February 2018

Wir führen eine Fluoreszenz‐basierte Methode ein, die es ermöglicht, die Anzahl der Ligationspunkte in einem photochemisch hergestellten Polymernetzwerk zu bestimmen, und sprechen hiermit die schwierige Frage an, wie man die Anzahl an Verbindungspunkten in einem Netzwerk quantifiziert. Wohldefinierte α,ω‐Tetrazol‐gekappte Polymerstränge wurden mittels RAFT‐Polymerisation hergestellt und mit einem Trimaleimid mittels einer durch UV‐Bestrahlung initiierten Nitril‐Imin‐vermittelten Tetrazol‐En‐Cycloaddition vernetzt. Dadurch wird für jeden Ligationspunkt ein fluoreszierender Pyrazolinring geformt und ein fluoreszierendes Netzwerk gebildet, das durch Aminolyse der Trithiocarbonatfunktionalitäten wieder aufgelöst werden kann und somit in löslichen Fragmenten resultiert. Die Fluoreszenzemission der löslichen Netzwerkfragmente korreliert direkt mit der Anzahl der Pyrazolineinheiten im Netzwerk und somit kann die sonst schwer zu erfassende Anzahl der Netzwerkpunkte bestimmt werden. Die hier vorgestellte Strategie basiert auf einer Fluoreszenzablesung und stellt eine leistungsfähige jedoch einfache Strategie dar, um den Herstellungsprozess eines Netzwerkes zu quantifizieren, und ist darüber hinaus auf die Gruppe der Polymere, die mittels RAFT hergestellt werden können, anwendbar.
Enzymatischer oder In‐vivo‐Einbau von Propargylgruppen in Kombination mit Klick‐Chemie zur Anreicherung und Detektion von Methyltransferase‐Zielsequenzen in RNA
Authors: Hartstock Katja , Nilges Benedikt S. , Ovcharenko Anna , Cornelissen Nicolas V. , Püllen Nikolai , Lawrence‐Dörner Ann‐Marie , Leidel Sebastian A. , Rentmeister Andrea
Published: February 2018

Die präzise, transkriptomweite Kartierung von m6A‐Positionen, einer der häufigsten internen Modifikationen in eukaryotischer mRNA, ist von großem Interesse. Eine Polymerase‐basierte Detektion von m6A ist schwierig, da die Modifikation keinen Einfluss auf die Watson‐Crick‐Basenpaarung hat. Ein chemisch‐biologischer Ansatz wurde entwickelt, der die präzise Kartierung von Zielsequenzen von Methyltransferasen (MTase) durch Einbau einer bioorthogonalen Propargylgruppe in vitro und in Zellen ermöglicht. Die Propargylgruppe wird hierbei enzymatisch von Wildtyp‐METTL3‐METTL14 angebracht. Nach Biokonjugation und Reinigung bricht die reverse Transkription an den m6A‐Positionen in 65 % der Fälle ab. Dies ermöglicht die Detektion der METTL3‐METTL14‐Zielsequenzen durch Sequenzierungsmethoden der nächsten Generation. Der metabolische Einbau von Propargylgruppen in MTase‐Zielsequenzen gelang auch in vivo mithilfe von Propargyl‐l‐selenohomocystein; so konnten bekannte rRNA‐Methylierungsstellen validiert werden.
Crystalline Radicals Derived from Classical N‐Heterocyclic Carbenes
Authors: Rottschäfer Dennis , Neumann Beate , Stammler Hans‐Georg , van Gastel Maurice , Andrada Diego M. , Ghadwal Rajendra S.
Published: February 2018

One‐electron reduction of C2‐arylated 1,3‐imidazoli(ni)um salts (IPrAr)Br (Ar=Ph, 3 a; 4‐DMP, 3 b; 4‐DMP=4‐Me2NC6H4) and (SIPrAr)I (Ar=Ph, 4 a; 4‐Tol, 4 b) derived from classical NHCs (IPr=:C{N(2,6‐iPr2C6H3)}2CHCH, 1; SIPr=:C{N(2,6‐iPr2C6H3)}2CH2CH2, 2) gave radicals [(IPrAr)]. (Ar=Ph, 5 a; 4‐DMP, 5 b) and [(SIPrAr)]. (Ar=Ph, 6 a; 4‐Tol, 6 b). Each of 5 a,b and 6 a,b exhibited a doublet EPR signal, a characteristic of monoradical species. The first solid‐state characterization of NHC‐derived carbon‐centered radicals 6 a,b by single‐crystal X‐ray diffraction is reported. DFT calculations indicate that the unpaired electron is mainly located at the original carbene carbon atom and stabilized by partial delocalization over the adjacent aryl group.
Customizing the Electrochemical Properties of Carbon Nanodots by Using Quinones in Bottom‐Up Synthesis
Authors: Rigodanza Francesco , Đorđević Luka , Arcudi Francesca , Prato Maurizio
Published: February 2018

We show how the redox potentials of carbon nanodots (CNDs) can be modulated by employing quinones as electroactive precursors during a microwave‐assisted synthesis. We prepared and characterized a redox library of CNDs, demonstrating that this approach can promote the use of carbon nanodots for ad hoc applications, including photocatalysis.
The Dewar Isomer of 1,2‐Dihydro‐1,2‐azaborinines: Isolation, Fragmentation, and Energy Storage
Authors: Edel Klara , Yang Xinyu , Ishibashi Jacob S. A. , Lamm Ashley N. , Maichle‐Mössmer Cäcilia , Giustra Zachary X. , Liu Shih‐Yuan , Bettinger Holger F.
Published: February 2018

The photochemistry of 1,2‐dihydro‐1,2‐azaborinine derivatives was studied under matrix isolation conditions and in solution. Photoisomerization occurs exclusively to the Dewar valence isomers upon irradiation with UV light (>280 nm) with high quantum yield (46 %). Further photolysis with UV light (254 nm) results in the formation of cyclobutadiene and an iminoborane derivative. The thermal electrocyclic ring‐opening reaction of the Dewar valence isomer back to the 1,2‐dihydro‐1‐tert‐butyldimethylsilyl‐2‐mesityl‐1,2‐azaborinine has an activation barrier of (27.0±1.2) kcal mol−1. In the presence of the Wilkinson catalyst, the ring opening occurs rapidly and exothermically (ΔH=(−48±1) kcal mol−1) at room temperature.
Novel core‐sheath antimicrobial nanofibrous mats
Authors: Kemp Renier , Klumperman Bert , Gule Nonjabulo Prudence
Published: February 2018

The poor mechanical properties of electrospun materials remain one of the major hindrances toward their practical application. In this study, we report the synthesis of core‐sheath nanofibrous mats to enhance the mechanical properties of an antimicrobial polymer nanofiber for application in filter media. This objective was achieved via coaxial electrospinning of poly[styrene‐co‐N‐(N′,N′‐dimethyl‐3‐aminopropyl)maleimide] as the sheath which is an antimicrobial polymer and nylon 6 polymer for the core which is well reported for exceptional mechanical properties. Extensive characterization of these fibers was performed using scanning electron microscopy, scanning transmission electron microscopy, confocal fluorescence microscopy as well as attenuated total reflectance Fourier transform spectroscopy to provide evidence of the core‐sheath morphology. Antimicrobial evaluation was also carried out on the fabricated fibers via the live/dead fluorescence technique. This was done to determine if the poly[styrene‐co‐N‐(N′,N′‐dimethyl‐3‐aminopropyl)maleimide] retained its antimicrobial activity. The fibers were found to be effective against the Gram‐positive Staphylococcus aureus (ATCC25925) and Gram‐negative Pseudomonas aeruginosa (ATCC27853). Subsequent tensile testing and filtration experiments provided evidence that the incorporation of the nylon core improved mechanical properties of the nanofiber mats. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46303.
Variations of the Circle of Willis at the End of the Human Embryonic Period
Authors: Furuichi Kana , Ishikawa Aoi , Uwabe Chigako , Makishima Haruyuki , Yamada Shigehito , Takakuwa Tetsuya
Published: February 2018

Variations of the circle of Willis (CW) influence blood supply to the brain and adjacent structures in adults. We examined the formation of the CW in 20 human embryo samples at the end of the embryonic period using 3‐D reconstructions of serial histological sections. The CW was closed in all samples, and did not form in a single plane, but was composed of multiple stair‐like planes. The artery acutely curved at the caudal part of the CW, namely, at the inlet of the basilar artery and bifurcation of the P1 segment of the posterior cerebral artery (PCA), reflecting flexure of the mesencephalon and diencephalon at this stage. Variations were observed in 17 of 20 samples—only anterior parts (anterior communicating artery [Acom] and anterior cerebral artery [ACA]) in 10 samples, only posterior parts (posterior communicating artery [Pcom]) in one sample, and both anterior and posterior parts in six samples. Variations included the Acom formed as partially duplicated in three samples, duplicated in four, plexiform in three, and no channel as a result of a single azygos ACA in one. The ACA formed as duplicated in two, median ACA in two, and right hypoplasia in one. The Pcom formed in hypoplasia of either side in six samples. Variations observed in this study are similar to those observed in fetuses, neonates, and adults. The P1 segment of PCA was very large in all samples. The present observations indicate that variations in the CW are present from the initiation of CW formation. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc.
Ringversuch zur Ermittlung des Chlorideindringwiderstands von Mörtel und Beton
Authors: Schulze Joachim , Breit Wolfgang
Published: February 2018

In dem im Rahmen des DAfStb‐Forschungsprojekts V488 durchgeführten Ringversuch zur Bestimmung des Chloridmigrationskoeffizienten wurden neben einem Instandsetzungsmörtel, der sowohl händisch (PCC) als auch im Spritzverfahren (SPCC) verarbeitet werden kann, ein Vergussbeton C80/95 mit hoher Gefügedichtigkeit und ein Normalbeton C20/25 mit geringer Gefügedichtigkeit untersucht. Hierdurch wurde die Untersuchung von stark variierenden Chloridmigrationskoeffizienten ermöglicht. Die Prüfinstitute erhielten Bohrkerne der jeweiligen Produkte und führten daran Untersuchungen in Anlehnung an die derzeit gültigen Regelwerke durch. Die Ergebnisse zeigten, dass das Eindringverhalten von Chloriden in Mörtel und Beton mit unterschiedlichen Gefügedichtigkeiten mit ausreichender Präzision beurteilt werden konnte. Die Prüfstreuung des Verfahrens zur Bestimmung des Chloridmigrationskoeffizienten, ermittelt aus den Wiederhol‐ und Vergleichsvariationskoeffizienten der teilnehmenden Prüfinstitute, lag tendenziell unterhalb der im BAW‐Merkblatt „Chlorideindringwiderstand von Beton“ aufgeführten Präzisionsdaten (Wiederholpräzision 11 % und Vergleichspräzision 20 %) und wies somit eine höhere Präzision auf. Eine Zuordnung der untersuchten Instandsetzungsmörtel und Betone hinsichtlich den Anforderungen an den Chlorideindringwiderstand nach BAW‐Merkblatt bezüglich der Expositionsklassen XS1–XS3 und XD1–XD3 kann mit ausreichender Sicherheit erfolgen.
Systematic review of measurement tools to assess surgeons' intraoperative cognitive workload
Authors: Dias R D , Ngo-Howard M C , Boskovski M T , Zenati M A , Yule S J
Published: February 2018

Background

Surgeons in the operating theatre deal constantly with high-demand tasks that require simultaneous processing of a large amount of information. In certain situations, high cognitive load occurs, which may impact negatively on a surgeon's performance. This systematic review aims to provide a comprehensive understanding of the different methods used to assess surgeons' cognitive load, and a critique of the reliability and validity of current assessment metrics.

Methods

A search strategy encompassing MEDLINE, Embase, Web of Science, PsycINFO, ACM Digital Library, IEEE Xplore, PROSPERO and the Cochrane database was developed to identify peer-reviewed articles published from inception to November 2016. Quality was assessed by using the Medical Education Research Study Quality Instrument (MERSQI). A summary table was created to describe study design, setting, specialty, participants, cognitive load measures and MERSQI score.

Results

Of 391 articles retrieved, 84 met the inclusion criteria, totalling 2053 unique participants. Most studies were carried out in a simulated setting (59 studies, 70 per cent). Sixty studies (71 per cent) used self-reporting methods, of which the NASA Task Load Index (NASA-TLX) was the most commonly applied tool (44 studies, 52 per cent). Heart rate variability analysis was the most used real-time method (11 studies, 13 per cent).

Conclusion

Self-report instruments are valuable when the aim is to assess the overall cognitive load in different surgical procedures and assess learning curves within competence-based surgical education. When the aim is to assess cognitive load related to specific operative stages, real-time tools should be used, as they allow capture of cognitive load fluctuation. A combination of both subjective and objective methods might provide optimal measurement of surgeons' cognition.
Evaluation of cellular adhesion and organization in different microporous polymeric scaffolds
Authors: Asthana Amish , White Charles McRae , Douglass Megan , Kisaalita William S.
Published: February 2018

The lack of prediction accuracy during drug development and screening risks complications during human trials, such as drug‐induced liver injury (DILI), and has led to a demand for robust, human cell‐based, in vitro assays for drug discovery. Microporous polymer‐based scaffolds offer an alternative to the gold standard flat tissue culture plastic (2D TCPS) and other 3D cell culture platforms as the porous material entraps cells, making it advantageous for automated liquid handlers and high‐throughput screening (HTS). In this study, we optimized the surface treatment, pore size, and choice of scaffold material with respect to cellular adhesion, tissue organization, and expression of complex physiologically relevant (CPR) outcomes such as the presence of bile canaliculi‐like structures. Poly‐l‐lysine and fibronectin (FN) coatings have been shown to encourage cell attachment to the underlying substrate. Treatment of the scaffold surface with NaOH followed with a coating of FN improved cell attachment and penetration into pores. Of the two pore sizes we investigated (A: 104 ± 4 μm; B: 175 ± 6 μm), the larger pore size better promoted cell penetration while limiting tissue growth from reaching the hypoxia threshold. Finally, polystyrene (PS) proved to be conducive to cell growth, penetration into the scaffold, and yielded CPR outcomes while being a cost‐effective choice for HTS applications. These observations provide a foundation for optimizing microporous polymer‐based scaffolds suitable for drug discovery. © 2018 American Institute of Chemical EngineersBiotechnol. Prog., 34:505–514, 2018
GdX/UBL4A null mice exhibit mild kyphosis and scoliosis accompanied by dysregulation of osteoblastogenesis and chondrogenesis
Authors: Liang Jiao , Li Jun , Fu Yanxia , Ren Fangli , Xu Jiake , Zhou Mengyu , Li Peiyu , Feng Haotian , Wang Yinyin
Published: February 2018

GdX, also named ubiquitin‐like protein 4A, is a ubiquitin‐domain protein characterized by a ubiquitin‐like domain that regulates the movement of misfolded proteins from the endoplasmic reticulum membrane to proteasome. However, its function in skeletal biology remains unclear. Here, we report that GdX plays a crucial role in skeletal development as mice lacking GdX exhibit skeletal dysplasias, mild kyphosis, and scoliosis. During embryonic stage, GdX knockout mice display decreased bone mineral density and trabecular bone accompanied by delayed osteogenic formation. GdX knockout mice also have blended spine and small body size. At the molecular level, GdX knockout mice showed perturbed expression of osteogenesis‐related genes and cartilage developmental genes, indicative of altered differentiation of mesenchymal cell lineage. Collectively, our results uncovered GdX as a novel regulator in bone development and a potential candidate gene for skeletal dysplasias.
Solution Synthesis ofN,N‐Dimethylformamide‐Stabilized Iron‐Oxide Nanoparticles as an Efficient and Recyclable Catalyst for Alkene Hydrosilylation
Authors: Azuma Ryusei , Nakamichi Seiya , Kimura Jungo , Yano Hiroki , Kawasaki Hideya , Suzuki Takeyuki , Kondo Ryota , Kanda Yasuharu , Shimizu Ken‐ichi , Kato Kazuo , Obora Yasushi
Published: February 2018

Highly activated, monodispersedN,N‐dimethylformamide (DMF)‐stabilized iron‐oxide nanoparticles (Fe2O3NPs) were synthesized by using iron(III) acetylacetonate as a precursor under open‐air conditions. The resulting Fe2O3NPs were characterized by various techniques (e.g., transmission electron microscopy, dynamic light scattering, X‐ray diffraction, X‐ray photoelectron spectroscopy, FTIR spectroscopy, and X‐ray adsorption near‐edge structure). The Fe2O3NPs exhibited efficient catalytic activity for the hydrosilylation of alkenes without the need for further additives. An effective recycling process of the colloidal catalyst by extraction with a hexane/DMF system was developed, and recycling of the catalyst over five cycles did not result in any significant loss in catalytic activity.
Quality Analysis of Liquid‐Filled Crystalline Containers
Authors: Wellner Martha , Ulrich Joachim
Published: February 2018

Crystallization can be used for encapsulation in the pharmaceutical and food industries. In previous studies, the encapsulation of certain amounts of liquids was shown to be feasible, and crystalline container systems with milk or condensed milk as a filling were developed. Here, methods for quality analyses were investigated, with special focus on mechanical, chemical, thermodynamic, and kinetic properties. Mechanical stability was determined by employing a stability measurement device (crushing force). The pH values of the encapsulated liquids over time give only a rough idea of the shelf life. Investigating the mass loss is a suitable method as it allows conclusions concerning the level of permeability of the containers. The dissolvability and release time of the liquid can be determined via UV‐vis photometry.
Projection to latent structures with orthogonal constraints for metabolomics data
Authors: Stocchero Matteo , Riccadonna Samantha , Franceschi Pietro
Published: February 2018

Multivariate techniques based on projection methods such as Principal Component Analysis and Partial Least Squares (PLS) regression are widely applied in metabolomics. However, the effects of confounding factors and the presence of specific clusters in the data could force the projection to produce inefficient representations in the latent space, preventing the identification of the most relevant data variation. To overcome this issue, we introduce a general framework for projection methods, allowing an easy integration of orthogonal constraints, which help in reducing the effect of uninformative variations. In particular, the discussed algorithms address different scenarios. When known confounding factors can be explicitly encoded into a proper constraint matrix, orthogonally Constrained Principal Component Analysis (oCPCA) and orthogonally Constrained PLS2 (oCPLS2) can be used. Orthogonal PLS (OPLS) and post‐transformation of PLS2 (ptPLS2), instead, are suited to problems in which a constraint matrix cannot be defined. Finally, a data integration task is considered: Orthogonal two‐block PLS (O2PLS) and Orthogonal Wold's two‐block Mode A PLS (OPLS‐W2A) are used to identify the common variation between two data sets.
Theory Uncovers the Role of the Methionine–Tyrosine–Tryptophan Radical Adduct in the Catalase Reaction of KatGs: O2 Release Mediated by Proton‐Coupled Electron Transfer
Authors: Wang Binju , Fita Ignacio , Rovira Carme
Published: February 2018

Catalase–peroxidases (KatGs) are bifunctional enzymes exhibiting both peroxidase and substantial catalase activities. It is widely recognized from experiments that the catalatic activity of KatGs is correlated with a unique covalent adduct (M‐Y‐W) formed in the active site, but the exact role of this adduct was elusive up to now. Here, quantum mechanical/molecular mechanical (QM/MM) calculations and QM/MM metadynamics are employed to elucidate the molecular mechanism and the role of M‐Y‐W adduct in the catalase reaction. It is shown that O2 formation proceeds through a mechanism involving proton‐coupled electron transfer (PCET). The M‐Y‐W cation radical adduct, which is close to the heme, His112 and the HOO. radical intermediate, acts as an electron sink during the PCET process. The present study also highlights the structural differences and functional similarities between KatGs and monofunctional catalases.
Metal Cluster Models for Heterogeneous Catalysis: A Matrix‐Isolation Perspective
Authors: Hübner Olaf , Himmel Hans‐Jörg
Published: February 2018

Metal cluster models are of high relevance for establishing new mechanistic concepts for heterogeneous catalysis. The high reactivity and particular selectivity of metal clusters is caused by the wealth of low‐lying electronically excited states that are often thermally populated. Thereby the metal clusters are flexible with regard to their electronic structure and can adjust their states to be appropriate for the reaction with a particular substrate. The matrix isolation technique is ideally suited for studying excited state reactivity. The low matrix temperatures (generally 4–40 K) of the noble gas matrix host guarantee that all clusters are in their electronic ground‐state (with only a very few exceptions). Electronically excited states can then be selectively populated and their reactivity probed. Unfortunately, a systematic research in this direction has not been made up to date. The purpose of this review is to provide the grounds for a directed approach to understand cluster reactivity through matrix‐isolation studies combined with quantum chemical calculations.