bluuebunny/crossref_metadata_2025 huggingface dataset:
The implications of fault zone transformation on aseismic creep: Example of the North Anatolian Fault, Turkey
Authors: Kaduri Maor , Gratier Jean‐Pierre , Renard François , Çakir Ziyadin , Lasserre Cécile
Published: May 2017

Aseismic creep is observed at surface along several segments of the North Anatolian right‐lateral active fault in Turkey, a major plate boundary between Eurasia and Anatolia. Identifying the mechanisms that control creep and their temporal and spatial change represents a major challenge for predicting the mechanical evolution of active faults, the interplay between creep and earthquakes, and the link between short‐term observations from geodesy and the long‐term fault zone evolution. We combine geological observations, laboratory analyses, and imaging techniques, shedding new light on the mechanism of fault creep along the North Anatolian Fault (NAF) and its time‐dependent change. A clear correlation is shown between shallow creep and near‐surface fault gouge composition: locked segments of the NAF are mostly composed of massive limestones without clay gouges, whereas creeping segments comprise clay gouges that contain low‐friction minerals. Such fault gouges appear to result from a progressive change of initial volcanic host rocks during their deformation. Anastomosing cleavage develops during the first stage of displacement, leading to layering, oblique at first and then subparallel to the fault, which accommodates part of the aseismic creep by pressure solution. Soluble minerals are dissolved, leading to passive concentration of phyllosilicates in the gouges where alteration transformations by fluid flow produce low friction minerals. At the same time damage zones are fractured and fractures are sealed by carbonates. As a result, these mineralogical and structural transformations weaken the gouge and strengthen the damage zone leading to the change from diffuse to localized seismic‐aseismic zones.
The universal scaling characteristics of tropical oceanic rain clusters
Authors: Teo C.‐K. , Huynh H.‐N. , Koh T.‐Y. , Cheung K. K. W. , Legras B. , Chew L. Y. , Norford L.
Published: May 2017

Using multiyear satellite rainfall estimates, the distributions of the area, and the total rain rate of rain clusters over the equatorial Indian, Pacific, and Atlantic Oceans was found to exhibit a power law, in whichSrepresents either the cluster area or the cluster total rain rate andfS(s) denotes the probability density function of finding an event of sizes. The scaling exponentsζSwere estimated to be 1.66 ± 0.06 and 1.48 ± 0.13 for the cluster area and cluster total rain rate, respectively. The two exponents were further found to be related via the expected total rain rate given a cluster area. These results suggest that convection over the tropical oceans is organized into rain clusters with universal scaling properties. They are also related through a simple scaling relation consistent with classical self‐organized critical phenomena. The results from this study suggest that mesoscale rain clusters tend to grow by increasing in size and intensity, while larger clusters tend to grow by self‐organizing without intensification.
Merging high‐resolution satellite‐based precipitation fields and point‐scale rain gauge measurements—A case study in Chile
Authors: Yang Zhongwen , Hsu Kuolin , Sorooshian Soroosh , Xu Xinyi , Braithwaite Dan , Zhang Yuan , Verbist Koen M. J.
Published: May 2017

With high spatial‐temporal resolution, Satellite‐based Precipitation Estimates (SPE) are becoming valuable alternative rainfall data for hydrologic and climatic studies but are subject to considerable uncertainty. Effective merging of SPE and ground‐based gauge measurements may help to improve precipitation estimation in both better resolution and accuracy. In this study, a framework for merging satellite and gauge precipitation data is developed based on three steps, including SPE bias adjustment, gauge observation gridding, and data merging, with the objective to produce high‐quality precipitation estimates. An inverse‐root‐mean‐square‐error weighting approach is proposed to combine the satellite and gauge estimates that are in advance adjusted and gridded, respectively. The model is applied and tested with the Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks‐Cloud Classification System (PERSIANN‐CCS) estimates (daily, 0.04° × 0.04°) over Chile, for the 6 year period of 2009–2014. Daily observations from about 90% of collected gauges over the study area are used for model calibration; the rest of the gauged data are regarded as ground “truth” for validation. Evaluation results indicate high effectiveness of the model in producing high‐resolution‐precision precipitation data. Compared to reference data, the merged data (daily) show correlation coefficients, probabilities of detection, root‐mean‐square errors, and absolute mean biases that were consistently improved from the original PERSIANN‐CCS estimates. The cross‐validation evidences that the framework is effective in providing high‐quality estimates even over nongauged satellite pixels. The same method can be applied globally and is expected to produce precipitation products in near real time by integrating gauge observations with satellite estimates.
Simulated impacts of direct radiative effects of scattering and absorbing aerosols on surface layer aerosol concentrations in China during a heavily polluted event in February 2014
Authors: Qiu Yulu , Liao Hong , Zhang Renjian , Hu Jianlin
Published: May 2017

We quantified aerosol direct radiative effects on surface layer concentrations of aerosols during a heavily polluted event in the North China Plain (NCP, 35.4°N–41.2°N, 113.3°E–119.3°E) during 21–27 February 2014, using the chemistry version of the Weather Research and Forecasting (WRF‐Chem) Model. Comparisons of model results with observations showed that the WRF‐Chem model reproduced the spatial and temporal variations of meteorological variables reasonably well, but overestimated average PM2.5 concentration by 21.7% over the NCP during 21–27 February. The simulated direct radiative effects of total, absorbing, and scattering aerosols reduced the planetary boundary layer (PBL) heights by 111.4 m, 35.7 m, and 70.7 m, respectively, averaged over NCP and 21–27 February. The direct radiative effects of total aerosols induced increases in aerosol concentrations by 11.5% for
, 29.5% for
, 29.6% for
, 28.7% for organic carbon (OC), 26.7% for black carbon (BC), and 20.4% for PM2.5, respectively, averaged over the NCP during 21–27 February 2014. The increase in PM2.5 concentration averaged over the NCP and the haze event was 29.6 μg m−3 (16.8%) due to radiative effect of scattering aerosols, as a result of the decreases in PBL height and changes in secondary aerosol production rates. The corresponding increase in PM2.5 concentration owing to absorbing aerosols was 2.1 μg m−3 (1.0%), resulting from the offsetting impacts of changes in PBL height, wind near the surface, and chemical processes.
Riverine carbon fluxes to the South China Sea
Authors: Huang T. H. , Chen C. T. A. , Tseng H. C. , Lou J. Y. , Wang S. L. , Yang L. , Kandasamy S. , Gao X. , Wang J. T. , Aldrian E. , Jacinto G. S. , Anshari G. Z. , Sompongchaiyakul P. , Wang B. J.
Published: May 2017

The high precipitation around Southeast Asia results in abundant freshwater outflow, which transports terrestrial dissolved and particulate material to the world's largest marginal sea, namely, the South China Sea (SCS). To estimate the riverine carbon flux to the SCS, carbonate data from 42 rivers were collected. These results, combined with literature data for 13 rivers, indicate that the concentrations of dissolved inorganic carbon (DIC) are positively correlated with the cation exchange capacity and the bulk density, except for the Low Discharge category. The highest DIC concentration and flux are in the Low and Medium Discharge categories. Negative correlations exist between dissolved organic carbon (DOC) concentrations and the base saturation in the Low and High Discharge categories and between DOC and bulk density in the Low and Medium Discharge categories. However, the correlation between the DOC concentration and the organic carbon content in the soil is only significant in the Medium Discharge category. Once the negative exponential relationships between the particulate inorganic carbon (PIC) or the particulate organic carbon (POC) and the total suspended matter are determined, these can be used to estimate the PIC and POC carbon fluxes. Of the annual riverine carbon flux, 83.0 ± 8.1 Tg C, 40.14 ± 6.11 Tg is DIC, 25.03 ± 4.54 Tg is DOC, 1.83 ± 0.35 Tg is PIC, and 16.03 ± 2.87 Tg is POC. The total discharge amounts to 6.2–10.3% of the global riverine discharge for a sea covering only 1% of the world's ocean surface area and for watersheds covering only 2.2% of the global land mass.
Naturally occurring radium (Ra) in home drinking‐water wells in the Sandhills region of South Carolina, USA: Can high concentrations be predicted?
Authors: Schrag Jeffrey M.
Published: May 2017

A strong relationship exists between concentrations of several principal constituents of water chemistry and naturally occurring radium in water from home wells in the large Sandhills region of the inner coastal plain of South Carolina, United States, an area of common radium problems (75% (21 of 28 of randomly selected wells in the main study area were above the U.S. Environmental Protection Agency (USEPA) maximum contaminant level (MCL): 5 picocuries per liter for 226Ra plus 228Ra). Ingested radioactive radium is potentially carcinogenic, and water far above the MCL occurs in places. One focus here was to determine if elevated radium concentrations can reliably be predicted using more easily measured characteristics of water chemistry. The initial phase investigated (1) concentrations of radium in well water within a smaller (~10 km radius) test area of known common problems plus (2) the associated water chemistry. This revealed a correlation between elevated radium and raised electrical conductance, total dissolved solids, calcium, nitrate, magnesium, hardness, and lowered pH. All are potentially useful screening tools for the many other rural home wells of this region. Natural groundwater in these highly leached sands is of very low dissolved salt content of all types, and local human influence on geochemistry is thus indicated. Predictive utility was examined by two additional series of wells (1) of higher radium contamination or (2) of elevated calcium concentration, both identified from file data. Higher radium wells were retested for water chemistry and higher calcium wells for radium content. Overall, a similar association between radium and water chemistry was observed.
L band microwave remote sensing and land data assimilation improve the representation of prestorm soil moisture conditions for hydrologic forecasting
Authors: Crow W. T. , Chen F. , Reichle R. H. , Liu Q.
Published: May 2017

Recent advances in remote sensing and land data assimilation purport to improve the quality of antecedent soil moisture information available for operational hydrologic forecasting. We objectively validate this claim by calculating the strength of the relationship between storm‐scale runoff ratio (i.e., total streamflow divided by total rainfall accumulation in depth units) and prestorm surface soil moisture estimates from a range of surface soil moisture data products. Results demonstrate that both satellite‐based, L band microwave radiometry and the application of land data assimilation techniques have significantly improved the utility of surface soil moisture data sets for forecasting streamflow response to future rainfall events.
On the historical origins of the CEJ, DP2, and Ddyn current systems and their roles in the predictions of ionospheric responses to geomagnetic storms at equatorial latitudes
Authors: Amory‐Mazaudier C. , Bolaji O. S. , Doumbia V.
Published: May 2017

In this short letter, we recall the differences between the counter electrojet (CEJ), which is a phenomenon observed on the magnetically quiet days and the disturbance dynamo (Ddyn), which can be observed during and after a geomagnetic storm. The CEJ is well known to occur near the geomagnetic dip equator. It can be identified by a reversal in the horizontal component (H) of the geomagnetic field daily regular variations. In contrast to equatorial electrojet (EEJ) that flows eastward in the daytime, the CEJ is considered to flow westward. The magnetic signatures of the reversed solar quiet (Sq) current at the low latitude during magnetic storms are due to the Ddyn. This disturbance (Ddyn) is produced by current systems that are driven by thermospheric storm winds originating from the Joule heating of enhanced high‐latitude currents. The DP2 is the magnetic effect of current systems at high latitudes. These currents are associated with the coupling of magnetosphere and ionosphere through geomagnetic field lines. They are associated to the magnetospheric convection. During intense magnetic storms these high‐latitude currents are enhanced and their magnetic effects can extend toward the low latitudes. This work shows that the study of magnetic perturbations makes it possible to understand the disturbances of the ionospheric electric currents. The use of an efficient treatment of the magnetic signals makes it possible to separate the magnetic effects of the different perturbations prompt penetration of the magnetospheric convection electric field and disturbance dynamo electric field. This was performed in the paper Nava et al. (2016).
Reconciling modeling with observations of radiative absorption of black carbon aerosols
Authors: Chen Bing , Zhu Zhejing , Wang Xinfeng , Andersson August , Chen Jianmin , Zhang Qingzhu , Gustafsson Örjan
Published: May 2017

The physical treatment of internal mixing and aging of black carbon (BC) aerosols that allow for enhanced solar absorption of the BC is an important parameterization in climate models. Many climate models predict a factor of 2–3 lower aerosol absorption optical depth (AAOD) than the atmospheric columnar absorption observed from ground‐based networks such as AERONET, likely because these models do not parameterize properly the BC absorption enhancement (EMAC). Models that are configured with an internal mixing have predicted large variations of EMAC, which are poorly constrained from ambient measurements. We determined the BC EMAC from aerosol coatings with a two‐step solvent experiment to remove both organic and inorganic coatings in ambient fine particulate matter (PM2.5). Observations in a rural North China site showed that the EMAC varied from 1.4 to 3. The EMAC increases simultaneously with SO42−/EC ratios, suggesting the photochemical production of sulfate coatings enhanced BC absorption. A global climate model, parameterized to account for these observational constraints, verifies that sulfates are primary drivers of the BC absorption enhancement in severely polluted area in China. This magnification of the radiative forcing of coated BC is stronger by a factor of ~2 than predicted by the standard parameterization (external mixing) in the climate model and is in better agreement with AERONET observations of AAOD. This result would be useful for testing the representation of solar absorption by BC‐containing particles in the newer generation of climate models.
Wild Bootstrap
Authors: Martin Michael A.
Published: May 2017

The wild bootstrap is a resampling method designed for regression problems with heteroscedastic error structure. The name derives from its use of asingleresidual to estimate the entire conditional distribution of each response through the use of an auxiliary zero‐mean, unit variance random multiplier when resampling. This article describes the development, properties, and software implementation of the wild bootstrap and some of its extensions.
Production of Heterologous Storage Polysaccharides in Potato Plants
Authors: Huang Xing‐Feng , Vincken Jean‐Paul , Visser Richard G.F. , Trindade Luisa M.
Published: May 2017

Starch is the most important storage polysaccharide in higher plants. This polysaccharide is used in many industrial applications as it is abundant, renewable and biodegradable and it can be modified into a wide range of products used in food, animal feed, pharmaceuticals and industry. With the understanding of the starch biosynthesis pathway and the isolation of many of the genes involved in this process, the potential for producing novel starches with improved functionality through genetic modification of plants has become more clear. Several different strategies have been used to achieve the rational design of renewable polymers to meet specific requirements. One of these strategies is the regulation of starch biosynthesis and granule assembly in higher plants. A second strategy involves the expression of heterologous genes encoding biosynthetic or modifying enzymes from other organisms to produce novel products with novel functional properties. In this chapter, these recent developments in starch modification in potato plants, such as alteration of starch composition and production of novel storage polysaccharides, are reviewed.
Nitrate Reductase and Nitric Oxide
Authors: Kaiser Werner M. , Planchet Elisabeth , Rümer Stefan
Published: May 2017

Plants produce NO either by reduction of nitrite or by oxidation of more reduced N forms. Reductive NO formation from nitrite can be enzymatic via nitrate reductase (NR), mitochondrial electron transport or non‐enzymatic at acidic pH. In any case, NR is the major (if not the only) source for endogenous nitrite in plants. Therefore, NR properties and regulation are summarized here with respect to NO production. Reductive NO formation froml‐arginine or from hydroxylamines is also considered. Problems in quantifying NO production from nitrite and potential roles of NO in plants are discussed in context with nitrate reduction.
The Utilization of Nitrogen by Plants: A Whole Plant Perspective
Authors: Pilbeam David J.
Published: May 2017

The growth of whole plants is dependent on tissue N concentration. Plants that grow in N‐rich environments have higher internal N concentrations and a higher relative growth rate, as described by the N productivity concept. When supply of nitrate N is interrupted, growth is maintained from storage pools of unassimilated nitrate for a limited time. Plants with low N supply show low shoot growth, high root–shoot ratio and decreased leaf growth. N is allocated more to the uppermost leaves, where there is a higher requirement for photosynthetic enzymes and chlorophyll, and mobilized to seeds as the leaves senesce. In actively photosynthesizing leaves, N‐containing primary metabolites are present in relatively constant concentrations, although concentrations of N‐containing secondary metabolites are more variable. The acquisition of nitrate is largely dependent on mass flow across the soil, but acquisition of ammonium depends more on diffusion to the roots. In a crop, uptake over a growing season is regulated by plant demand. This demand is signalled from the shoots to the roots. Some adaptations of roots enable the acquisition of nitrogen before it is acquired by other plants, and species adapted to N‐rich soils have high leaf N concentrations and high specific leaf area, and out‐compete other species for light. Those plants with higher leaf N concentrations seem to be more susceptible to herbivory and attack by micro‐organisms, however.
Abiotic Stress and Metabolomics
Authors: Bowne Jairus , Bacic Antony , Tester Mark , Roessner Ute
Published: May 2017

Abiotic stress has major impacts on crop yields worldwide. In the field, multiple stresses often occur simultaneously, and interactions between these stresses will modify the physiological response of plants. We briefly review known tolerance mechanisms and describe approaches that led to their identification, and how new tolerance mechanisms may be identified using ‘omics technologies. We then focus on metabolomics technologies including data analysis, and the results of their application in abiotic stress research. Integration of multiple ‘omics datasets and their interpretation with existing genetic, physiological and morphological data is a challenge that is currently being addressed to enable further exploration and interpretation of metabolomic data. We conclude by discussing new developments in metabolomics, such as single cell measurements of stress responses and tissue‐based mass spectrometry imaging that will offer greater spatial resolution of sub‐cellular distribution of metabolites.
A Role for Metabolomics in Plant Ecology
Authors: van Dam Nicole M. , van der Meijden Eddy
Published: May 2017

Plant metabolomic analyses have been mostly applied to analyse metabolomes of crops and model species. However, metabolomic analyses may also be extremely valuable for plant ecologists. Because of the untargeted nature of most metabolomic platforms, the analyses will provide a comprehensive overview of both the primary and secondary plant metabolome. This is especially valuable for chemical ecologists studying plant–herbivore interactions, as both primary and secondary metabolites together determine the performance and preference of herbivores feeding on a plant. A few examples from the recent scientific literature exemplify how metabolomics may yield novel knowledge on the effects of hybridization on plant chemistry, insect resistance and genotype × environment interactions that could not have been so easily obtained with targeted studies alone. Theories and hypotheses regarding optimal defence strategies in plants and invasive plant biology may also benefit from metabolomic analysis. Testable hypotheses built on our current knowledge of plant responses to herbivores and competition may be substantiated and expanded based on metabolomic analyses. Despite some of the limitations that metabolomics analyses may have, the implementation of broad‐spectrum chemical analysis in plant ecology will definitively open up new horizons for plant ecologists and enhance our understanding of the importance of plant chemistry in plant–environment interactions for fundamental and applied research.
Spatially Resolved Plant Metabolomics
Authors: Sumner Lloyd W. , Yang Dong Sik , Bench Bennie J. , Watson Bonnie S. , Li Chao , Jones A. Daniel
Published: May 2017

Primary and secondary metabolism of plants are segregated amidst many differentiated and specialized plant organs, tissues, cells and organelles. The specialized physiology of anatomically distinct components contribute to highly sophisticated, autotrophic systems that are foundational to global energy, ecology, biology and nutrition. An established literature base exists for focused studies of metabolism in specific organs, tissue, cells, and this literature is briefly reviewed here. However, modern metabolic studies are moving towards more global metabolite analyses (i.e. metabolomics and systems biology) with high anatomical, spatial and temporal resolution to better understand the massive complexity of plant systems. Several current examples of such spatially resolved metabolomics experiments are provided here, and the current prospects of metabolite imaging reviewed. Although current metabolomics approaches have been quite informative, they are still constrained by multiple factors. The major challenges that still face plant metabolomics are metabolite annotation, depth‐of‐coverage or comprehensiveness, instrumental sensitivity and dynamic range. These plant metabolomics challenges are discussed in general and relative to temporally and spatially resolved metabolomics.
Data Processing, Metabolomic Databases and Pathway Analysis
Authors: Fiehn Oliver , Kind Tobias , Barupal Dinesh Kumar
Published: May 2017

Metabolomics relies on a variety of bioinformatics tools aiming to derive information from data. Data acquisition with chromatography‐coupled mass spectrometry yields high volumes of raw data that need to be processed to achieve de‐noised and meaningful biochemical data that subsequently can be presented for statistics and pathway analysis in a coherent manner. A variety of new tools and algorithms have recently been developed that help in this process. Nevertheless, a surprisingly low number of metabolic signals can be unambiguously identified. If cutting‐edge methods are used, we can confidently interpret signals that can neither be identified by reference standards nor annotated by database matching as ‘novel metabolites’. Such methods may comprise high‐resolution, high‐accurate mass data in conjunction with good data alignment programs that perform peak picking and deconvolution, calculation of elemental formulas, database queries and constraining hit lists by interpreting mass spectral fragmentations and retention‐based metabolomic libraries. In an effort to improve standardizations for metabolomic reports, we propose that not only metabolites must be named but also, for all reported metabolites, identifiers or structure codes (InChI keys) from public (bio)chemical databases need to be detailed. Machine‐readable structures will vastly accelerate our knowledge of the magnitude and importance of the metabolome in various plant species, organs and physiological conditions. We detail how well‐annotated metabolome data can then be used to visualize and interrogate biochemical pathways by matching information to the broad plant databases that currently exist.
Comment on “An Experimental Study on Evolution of Grain‐Scale Stress/Strain and Geometrical Necessary Dislocations in Advanced TA15 Titanium Alloy during Uniaxial Tension Deformation”
Authors: Britton Thomas Benjamin
Published: May 2017

This is a brief comment to highlight and discuss issues with regards to the high resolution, cross correlation‐based, electron backscatter diffraction (HR‐EBSD) results presented within the work of He et al. (2016) Advanced Engineering Materials. In this comment, two specific concerns are raised: one, the stress measurements, reported to be as high as 20 GPa, are unreasonable and due to a known artefact in the form of HR‐EBSD analysis, which has been corrected in state‐of‐the‐art measurements by patterning remapping; and two, the GND field measurements are incorrectly calculated and show the variations in lattice rotation and are no derived from the gradient of the lattice rotation field, as required when following Nye's analysis. An example of reasonable data is presented to highlight how these artefacts can be avoided in practice using more appropriate analysis techniques.
Ly6Chi Monocytes Delivering pH‐Sensitive Micelle Loading Paclitaxel Improve Targeting Therapy of Metastatic Breast Cancer
Authors: Lang Tianqun , Dong Xinyue , Huang Yan , Ran Wei , Yin Qi , Zhang Pengcheng , Zhang Zhiwen , Yu Haijun , Li Yaping
Published: May 2017

Many immune cells are capable of homing to sites of disease and eradicating infections and abnormal cells. However, their efficacy is usually down‐regulated in tumor microenvironments and it is difficult to boost. It is presumed that the anticancer activity of immune cells can be improved by integrating an additional therapeutic modality such as chemotherapy into the cells. Here, Ly6Chi monocytes armed with the paclitaxel (PTX)‐loading pH‐sensitive micelle (PM), termed as PM@MC, are prepared. The PM internalization does not significantly affect the properties of the host Ly6Chi monocytes. In the 4T1 metastatic breast cancer mice model, PM@MCs home to both primary tumor and the lung metastasis foci. PM@MC exhibit 15‐fold higher intratumor PTX accumulation than the commercial PTX injection, and achieve a tumor inhibiting rate of 96.8% and a lung metastasis suppression rate of 99.2%. No significant change is recorded in histology of major organs and in hematological and biochemical parameters after PM@MC treatment. The pH‐sensitive micelle/Ly6Chi monocyte drug delivery device thus has the application potential in the targeting therapy of breast cancer with metastasis.
2‐Keto‐3‐Deoxy‐l‐Rhamnonate Aldolase (YfaU) as Catalyst in Aldol Additions of Pyruvate to Amino Aldehyde Derivatives
Authors: Hernández Karel , Gómez Ariadna , Joglar Jesús , Bujons Jordi , Parella Teodor , Clapés Pere
Published: May 2017

4‐Hydroxy‐2‐keto acid derivatives are versatile building blocks for the synthesis of amino acids, hydroxy carboxylic acids and chiral aldehydes. Pyruvate aldolases are privileged catalysts for a straightforward access to this class of keto acid compounds. In this work, a Class II pyruvate aldolase from Escherichia coli K‐12, 2‐keto‐3‐deoxy‐l‐rhamnonate aldolase (YfaU), was evaluated for the synthesis of amino acid derivatives of proline, pipecolic acid, and pyrrolizidine‐3‐carboxylic acid. The aldol addition of pyruvate to N‐protected amino aldehydes was the key enzymatic aldol addition step followed by catalytic intramolecular reductive amination. The corresponding N‐Cbz‐amino‐4‐hydroxy‐2‐keto acid (Cbz=benzyloxycarbonyl) precursors were obtained in 51–95% isolated yields and enantioselectivity ratios from 26:74 to 95:5, with chiral α‐substituted N‐Cbz‐amino aldehydes. (S)‐N‐Cbz‐amino aldehydes gave aldol adducts with preferentially (R)‐configuration at the newly formed stereocenter, whereas the contrary is true for (R)‐N‐Cbz‐amino aldehydes. Addition reactions to achiral amino aldehydes rendered racemic aldol adducts. Molecular models of the pre‐reaction ternary complexes YfaU‐pyruvate enolate‐acceptor aldehyde were constructed to explain the observed stereochemical outcome of the reactions. Catalytic reductive amination of the aldol adducts yielded 4‐hydroxy‐2‐pipecolic acid, and unprecedented C‐5 substituted 4‐hydroxyproline and pyrrolizidine‐3‐carboxylic acid derivatives.

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Triphasic 2D Materials by Vertically Stacking Laterally Heterostructured 2H‐/1T′‐MoS2 on Graphene for Enhanced Photoresponse
Authors: Cui Weili , Xu Shanshan , Yan Bo , Guo Zhihua , Xu Qun , Sumpter Bobby G. , Huang Jingsong , Yin Shiwei , Zhao Huijun , Wang Yun
Published: May 2017

Recently the applications of 2D materials have been broadened by engineering their mechanical, electronic, and optical properties through either lateral or vertical hybridization. Here, the successful design and fabrication of a novel triphasic 2D material by vertically stacking lateral 2H‐/1T′‐molybdenum disulfide (MoS2) heterostructures on graphene with the assistance of supercritical carbon dioxide is reported. This triphasic structure is experimentally shown to significantly enhance the photocurrent densities for hydrogen evolution reactions. First‐principles theoretical analyses reveal that the improved photoresponse should be ascribed to the beneficial band alignments of the triphasic heterostructure. More specifically, electrons can efficiently hop to the 1T′‐MoS2 phase via the highly conductive graphene layer as a result of their strong vertical interfacial electronic coupling. Subsequently, the electrons acquired on the 1T′‐MoS2 phase are exploited to fill the photoholes on the photoexcited 2H‐MoS2 phase through the lateral heterojunction structure, thereby suppressing the recombination process of the photoinduced charge carriers on the 2H‐MoS2 phase. This novel triphasic concept promises to open a new avenue to widen the molecular design of 2D hybrid materials for photonics‐based energy conversion applications.
Multifunctional Nanoionic Devices Enabling Simultaneous Heterosynaptic Plasticity and Efficient In‐Memory Boolean Logic
Authors: Yang Yuchao , Yin Minghui , Yu Zhizhen , Wang Zongwei , Zhang Teng , Cai Yimao , Lu Wei D. , Huang Ru
Published: May 2017

The development of smart, scalable, and power efficient computers relies on innovative technologies that can distribute memory alongside processing, such as emerging neuromorphic computing and in‐memory logic technologies. Here, a type of vertical 3‐terminal oxide based nanoionic device capable of implementing heterosynaptic plasticity and nonvolatile Boolean logic simultaneously is demonstrated. The heterosynaptic plasticity endows the devices with facilely tunable synaptic kinetics via tailoring modulatory signals, which is shown to be crucial for achieving optimized learning scheme, therefore offering promising building blocks for neuromorphic computing. Furthermore, it is demonstrated that these heterosynaptic devices can simultaneously be utilized to implement nonvolatile Boolean logic with improved efficiency compared with existing approaches, therefore implying in‐memory computing potentialities. The heterosynaptic devices with such multifunctionality thus hold great potential for next‐generation non‐von Neumann computing applications.
Scalable, Self‐Aligned Printing of Flexible Graphene Micro‐Supercapacitors
Authors: Hyun Woo Jin , Secor Ethan B. , Kim Chang‐Hyun , Hersam Mark C. , Francis Lorraine F. , Frisbie C. Daniel
Published: May 2017

Graphene micro‐supercapacitors (MSCs) are an attractive energy storage technology for powering miniaturized portable electronics. Despite considerable advances in recent years, device fabrication typically requires conventional microfabrication techniques, limiting the translation to cost‐effective and high‐throughput production. To address this issue, we report here a self‐aligned printing process utilizing capillary action of liquid inks in microfluidic channels to realize scalable, high‐fidelity manufacturing of graphene MSCs. Microstructured ink receivers and capillary channels are imprinted on plastic substrates and filled by inkjet printing of functional materials into the receivers. The liquid inks move under capillary flow into the adjoining channels, allowing reliable patterning of electronic materials in complex structures with greatly relaxed printing tolerance. Leveraging this process with pristine graphene and ion gel inks, miniaturized all‐solid‐state graphene MSCs are demonstrated to concurrently achieve outstanding resolution (active footprint: <1 mm2, minimum feature size: 20 µm) and yield (44/44 devices), while maintaining a high specific capacitance (268 µF cm–2) and robust stability to extended cycling and bending, establishing an effective route to scale down device size while scaling up production throughput.
Highly Conductive, Lightweight, Low‐Tortuosity Carbon Frameworks as Ultrathick 3D Current Collectors
Authors: Chen Chaoji , Zhang Ying , Li Yiju , Kuang Yudi , Song Jianwei , Luo Wei , Wang Yanbin , Yao Yonggang , Pastel Glenn , Xie Jia , Hu Liangbing
Published: May 2017

The growing demand for advanced energy storage techniques and devices has driven the energy storage market to strive for higher performance, longer cycling life, and better safety. Thick electrode design enabling more electroactive materials has the potential to significantly improve the energy density on device level yet faces major challenges of slow ion transport and high deformability. Here, inspired by natural wood materials with aligned channels along the tree growth direction, a highly conductive, lightweight, and low‐tortuosity carbon framework (CF) directly carbonized from natural wood as an ultrathick 3D current collector is demonstrated. Benefiting from the uniqueness of the multichanneled CF, an ultrathick 3D electrode of lithium iron phosphate filled carbon framework with a large thickness of 800 µm and active material mass loading of 60 mg cm−2 delivers a rational capacity of 7.6 mAh cm−2 (95 Ah L−1 based on volume), long cycling life, and lower deformability with enhanced mechanical properties. This work presents a design concept for thick electrode toward high performance energy storage devices that are not limited to lithium‐ion batteries.
Photocontrollable Supramolecular Self‐Assembly of a Porphyrin Derivative that Contains a Polyhedral Oligomeric Silsesquioxane (POSS)
Authors: Zhang Yong , Yue Tao , Cao Hongliang , Gao Yun , Zhang Weian
Published: May 2017

In this study, we have synthesized a new photosensitive organic–inorganic POSS‐containing hybrid porphyrin derivative (H2TPP−Azo−POSS), in which azobenzene was used as a bridge to conjugate the porphyrin and POSS, by using click chemistry. The self‐assembly behavior of H2TPP−Azo−POSS was studied at different concentrations in CHCl3 and in CHCl3/n‐hexane mixed solvent systems. Our results showed that the self‐assembled morphology of H2TPP−Azo−POSS could be tuned by varying the concentration and polarity of the solvent. Spherical micelles and linear nanowires could be obtained in CHCl3, whilst vesicles could be formed in CHCl3/n‐hexane mixtures with low polarities. The supramolecular self‐assembled morphologies of H2TPP−Azo−POSS demonstrated a light‐triggered transition behavior, whilst the size of the assembled aggregates decreased significantly under UV irradiation.
Carbon–Fluorine Reductive Elimination from Nickel(III) Complexes
Authors: Lee Heejun , Börgel Jonas , Ritter Tobias
Published: May 2017

We report a C−F reductive elimination from a characterized first‐row aryl metal fluoride complex. Reductive elimination from the presented nickel(III) complexes is faster than C−F bond formation from any other characterized aryl metal fluoride complex.
A Sustainable Redox‐Flow Battery with an Aluminum‐Based, Deep‐Eutectic‐Solvent Anolyte
Authors: Zhang Changkun , Ding Yu , Zhang Leyuan , Wang Xuelan , Zhao Yu , Zhang Xiaohong , Yu Guihua
Published: May 2017

Nonaqueous redox‐flow batteries are an emerging energy storage technology for grid storage systems, but the development of anolytes has lagged far behind that of catholytes due to the major limitations of the redox species, which exhibit relatively low solubility and inadequate redox potentials. Herein, an aluminum‐based deep‐eutectic‐solvent is investigated as an anolyte for redox‐flow batteries. The aluminum‐based deep‐eutectic solvent demonstrated a significantly enhanced concentration of circa 3.2 m in the anolyte and a relatively low redox potential of 2.2 V vs. Li+/Li. The electrochemical measurements highlight that a reversible volumetric capacity of 145 Ah L−1 and an energy density of 189 Wh L−1 or 165 Wh kg−1 have been achieved when coupled with a I3−/I− catholyte. The prototype cell has also been extended to the use of a Br2‐based catholyte, exhibiting a higher cell voltage with a theoretical energy density of over 200 Wh L−1. The synergy of highly abundant, dendrite‐free, multi‐electron‐reaction aluminum anodes and environmentally benign deep‐eutectic‐solvent anolytes reveals great potential towards cost‐effective, sustainable redox‐flow batteries.
Rhodium‐Catalyzed Addition of Aryl Boronic Acids to 2,2‐Disubstituted Malononitriles
Authors: Malapit Christian A. , Caldwell Donald R. , Luvaga Irungu K. , Reeves Jonathan T. , Volchkov Ivan , Gonnella Nina C. , Han Zhengxu S. , Busacca Carl A. , Howell Amy R. , Senanayake Chris H.
Published: May 2017

β‐Ketonitriles bearing a quaternary carbon at the 2‐position were prepared through Rh‐catalyzed addition of aryl boronic acids to 2,2‐disubstituted malononitriles. In contrast to the previously described transnitrilative cyanation of aryl boronic acids with dialkylmalononitriles, the present reaction avoids retro‐Thorpe collapse of the intermediate addition product through the use of a milder base. The reaction was amenable to a variety of aryl boronic acids and disubstituted malononitriles, providing a diverse array of β‐ketonitriles. The products could be further derivatized to valuable chiral α,α‐disubstituted‐β‐aminonitriles through addition reactions to the corresponding N‐tert‐butanesulfinyl imines.
Substituenteneffekte auf Stapelwechselwirkungen parallel verschobener π‐Systeme: der Abstand ist entscheidend
Authors: Riwar Leslie‐Joana , Trapp Nils , Kuhn Bernd , Diederich François
Published: May 2017

Wirt‐Gast‐Systeme aus substituierten Rebek‐Imiden als Rezeptoren und 2,6‐Di(isobutyramido)pyridin als Ligand wurden zur Untersuchung von Substituenteneffekten auf π‐π‐Stapelwechselwirkungen parallel verschobener π‐Systeme eingesetzt. Änderungen des intermolekularen Abstands zwischen dem para‐Substituenten der aromatischen Plattform des Imid‐Rezeptors und dem Pyridinring des Gasts resultierten in stark unterschiedlichen Substituenteneffekten. Eine kurze Ethin‐1,2‐diyl‐Brücke zwischen Rebek‐Imid und aromatischer Plattform führte zu einer partiellen Überlappung des Gasts mit dem Substituenten, die unabhängig von dessen elektronischen Eigenschaften zu einer verstärkten π‐π‐Stapelwechselwirkung führte (Wheeler‐Houk‐Modell). Ersatz der Ethin‐1,2‐diyl‐ durch die längere Buta‐1,3‐diin‐1,4‐diyl‐Brücke verhinderte direkte Substituent‐Gast‐Wechselwirkungen durch den Raum. Es wurde eine lineare Korrelation zwischen logKa (Ka=Assoziationskonstante) und dem Hammett‐Substituentenparameter σpara gefunden, wodurch die Vorhersage des Hunter‐Sanders‐Modells experimentell bestätigt wurde.
Generierung einer kleinen HOMO‐LUMO‐Lücke und intramolekulare C‐H‐Borylierung durch Diboren‐Anthracen‐Orbitalinterkalation
Authors: Wang Sunewang R. , Arrowsmith Merle , Böhnke Julian , Braunschweig Holger , Dellermann Theresa , Dewhurst Rian D. , Kelch Hauke , Krummenacher Ivo , Mattock James D. , Müssig Jonas H. , Thiess Torsten , Vargas Alfredo , Zhang Jiji
Published: May 2017

Diboren 1 wurde durch Reduktion einer Mischung aus 1,2‐Di‐9‐anthryl‐1,2‐dibromdiboran(4) (6) und Trimethylphosphan mit Kaliumgraphit dargestellt. Die Molekülstruktur von 1 zeigt, dass die Anthrylringe zueinander parallel und in Bezug auf das Diboren‐π(B=B)‐System orthogonal angeordnet sind. Diese verdrehte Konformation ohne signifikante Konjugation erlaubt eine Interkalation des relativ hoch liegenden π(B=B)‐Orbitals mit dem tief liegenden π*‐Orbital der Anthryl‐Einheit, was zu einer kleinen HOMO‐LUMO‐Lücke und letztlich zur C‐H‐Borylierung des Anthryl‐Liganden führt. Die HOMO‐LUMO‐Energielücke wurde durch den Beginn der Absorptionsbande bei der längsten Wellenlänge im UV‐vis‐Spektrum auf 1.57 eV geschätzt (THF, λonset=788 nm). Mit elementarem Selen ließ sich Verbindung 1 quantitativ zum Diboraseleniran 8 umsetzen. Durch ein weiteres Äquivalent Selen wird unter oxidativer Abspaltung eines Phosphan‐Liganden und Spaltung der B‐B‐ und C1‐H‐Bindungen das cyclische 1,9‐Diborylanthracen 9 erhalten.
Catalytic Asymmetric [3+1]‐Cycloaddition Reaction of Ylides with Electrophilic Metallo‐enolcarbene Intermediates
Authors: Deng Yongming , Massey Lynée A. , Zavalij Peter Y. , Doyle Michael P.
Published: May 2017

The first asymmetric [3+1]‐cycloaddition was successfully achieved by copper(I) triflate/double‐sidearmed bisoxazoline complex catalyzed reactions of β‐triisopropylsilyl‐substituted enoldiazo compounds with sulfur ylides. This methodology delivered a series of chiral cyclobutenes in good yields with high enantio‐ and diastereoselectivities (up to 99 % ee, and >20:1 d.r.). Additionally, the [3+1]‐cycloaddition of catalytically generated metallo‐enolcarbenes was successfully extended to reaction with a stable benzylidene dichlororuthenium complex.
Temperature‐Driven Planar Chirality Switching of a Pillar[5]arene‐Based Molecular Universal Joint
Authors: Yao Jiabin , Wu Wanhua , Liang Wenting , Feng Yujun , Zhou Dayang , Chruma Jason J. , Fukuhara Gaku , Mori Tadashi , Inoue Yoshihisa , Yang Cheng
Published: May 2017

The study of an enantiopure bicyclic pillar[5]arene‐based molecular universal joint (MUJ) by single‐crystal X‐ray diffraction allowed for the first time the unequivocal assignment of the absolute configuration of a planar chiral pillar[5]arene by circular dichroism spectroscopy. Crucially, the absolute configuration of the MUJ was switched reversibly by temperature, with an accompanying sign inversion of the anisotropy factor that varied by as much as 0.03, which is the largest value ever reported. Mechanistically, the reversible chirality switching of the MUJ is driven by the threading/dethreading motion of the fused ring and hence is dependent on both the size and nature of the ring and the solvent employed, reflecting the critical balance between the self‐complexation of the ring by pillar[5]arene, the solvation to the excluded ring, and the inclusion of solvent molecules in the cavity.
Single‐Molecule Photoactivation FRET: A General and Easy‐To‐Implement Approach To Break the Concentration Barrier
Authors: Peng Sijia , Sun Ruirui , Wang Wenjuan , Chen Chunlai
Published: May 2017

Single‐molecule fluorescence resonance energy transfer (sm‐FRET) has become a widely used tool to reveal dynamic processes and molecule mechanisms hidden under ensemble measurements. However, the upper limit of fluorescent species used in sm‐FRET is still orders of magnitude lower than the association affinity of many biological processes under physiological conditions. Herein, we introduce single‐molecule photoactivation FRET (sm‐PAFRET), a general approach to break the concentration barrier by using photoactivatable fluorophores as donors. We demonstrate sm‐PAFRET by capturing transient FRET states and revealing new reaction pathways during translation using μm fluorophore labeled species, which is 2–3 orders of magnitude higher than commonly used in sm‐FRET measurements. sm‐PAFRET serves as an easy‐to‐implement tool to lift the concentration barrier and discover new molecular dynamic processes and mechanisms under physiological concentrations.
Achiral Pyridine Ligand‐Enabled Enantioselective Radical Oxytrifluoromethylation of Alkenes with Alcohols
Authors: Cheng Yong‐Feng , Dong Xiao‐Yang , Gu Qiang‐Shuai , Yu Zhang‐Long , Liu Xin‐Yuan
Published: May 2017

A conceptually novel strategy with achiral pyridine as the ancillary ligand to stabilize high‐valent copper species for the first asymmetric radical oxytrifluoromethylation of alkenes with alcohols under CuI/phosphoric acid dual‐catalysis has been developed. The transformation features mild reaction conditions, a remarkably broad substrate scope and excellent functional group tolerance, offering an efficient approach to a wide range of trifluoromethyl‐substituted tetrahydrofurans bearing an α‐tertiary stereocenter with excellent enantioselectivity. Mechanistic studies support the presumed role of the achiral pyridine as a coordinative ligand on copper metal to stabilize the key transient reaction species involved in the asymmetric induction process.
Discovery of EGF Receptor Inhibitors That Are Selective for the d746‐750/T790M/C797S Mutant through Structure‐Based de Novo Design
Authors: Park Hwangseo , Jung Hoi‐Yun , Mah Shinmee , Hong Sungwoo
Published: May 2017

Next‐generation epidermal growth factor receptor (EGFR) inhibitors against the d746‐750/T790M/C797S mutation were discovered through two‐track virtual screening and de novo design. A number of nanomolar inhibitors were identified using 2‐aryl‐4‐aminoquinazoline as the molecular core and the modified binding energy function involving a proper dehydration term, which provides important structural insight into the key principles for high inhibitory activities against the d746‐750/T790M/C797S mutant. Furthermore, some of these EGFR inhibitors showed a greater than 1000‐fold selectivity for the d746‐750/T790M/C797S mutant over the wild type, as well as nanomolar activity against the mutant.
Selective synthesis of 3‐Selanylindoles from Indoles and Diselenides using IK/mCPBA system
Authors: Li Hongjie , Wang Xiaolong , Yan Jie
Published: May 2017

In the presence of a catalytic amount of KI combined with oxidantmCPBA, a convenient catalytic procedure is developed for the preparation of 3‐selanylindoles from indoles and diselenides. In this protocol, KI is first oxidized bymCPBA into hypoiodous acid, which reacts with diselenide to cleave Se‐Se bond. Thein situgenerated active electrophilic selenium species then reacts with indole, affording 3‐selanylindole via an electrophilic substitution mechanism. This catalytic selenation of indoles has mild reaction conditions and is a simple procedure, which extends the synthetic application of KI in organic synthesis.