bluuebunny/crossref_metadata_2025 huggingface dataset:
Benefits and Limitations of Real Options Analysis for the Practice of River Flood Risk Management
Authors: Kind Jarl M. , Baayen Jorn H. , Botzen W. J. Wouter
Published: March 2018

Decisions on long‐lived flood risk management (FRM) investments are complex because the future is uncertain. Flexibility and robustness can be used to deal with future uncertainty. Real options analysis (ROA) provides a welfare‐economics framework to design and evaluate robust and flexible FRM strategies under risk or uncertainty. Although its potential benefits are large, ROA is hardly used in todays' FRM practice. In this paper, we investigate benefits and limitations of a ROA, by applying it to a realistic FRM case study for an entire river branch. We illustrate how ROA identifies optimal short‐term investments and values future options. We develop robust dike investment strategies and value the flexibility offered by additional room for the river measures. We benchmark the results of ROA against those of a standard cost‐benefit analysis and show ROA's potential policy implications. The ROA for a realistic case requires a high level of geographical detail, a large ensemble of scenarios, and the inclusion of stakeholders' preferences. We found several limitations of applying the ROA. It is complex. In particular, relevant sources of uncertainty need to be recognized, quantified, integrated, and discretized in scenarios, requiring subjective choices and expert judgment. Decision trees have to be generated and stakeholders' preferences have to be translated into decision rules. On basis of this study, we give general recommendations to use high discharge scenarios for the design of measures with high fixed costs and few alternatives. Lower scenarios may be used when alternatives offer future flexibility.
Estimating River Surface Elevation From ArcticDEM
Authors: Dai Chunli , Durand Michael , Howat Ian M. , Altenau Elizabeth H. , Pavelsky Tamlin M.
Published: March 2018

ArcticDEM is a collection of 2‐m resolution, repeat digital surface models created from stereoscopic satellite imagery. To demonstrate the potential of ArcticDEM for measuring river stages and discharges, we estimate river surface heights along a reach of Tanana River near Fairbanks, Alaska, by the precise detection of river shorelines and mapping of shorelines to land surface elevation. The river height profiles over a 15‐km reach agree with in situ measurements to a standard deviation less than 30 cm. The time series of ArcticDEM‐derived river heights agree with the U.S. Geological Survey gage measurements with a standard deviation of 32 cm. Using the rating curve for that gage, we obtain discharges with a validation accuracy (root‐mean‐square error) of 234 m3/s (23% of the mean discharge). Our results demonstrate that ArcticDEM can accurately measure spatial and temporal variations of river surfaces, providing a new and powerful data set for hydrologic analysis.
Permian Paleogeography of the Eastern CAOB: Paleomagnetic Constraints From Volcanic Rocks in Central Eastern Inner Mongolia, NE China
Authors: Zhang Donghai , Huang Baochun , Zhao Jie , Meert Joseph G. , Zhang Ye , Liang Yalun , Bai Qianhui , Zhou Tinghong
Published: March 2018

We carried out a paleomagnetic investigation on Permian volcanic rocks from central eastern Inner Mongolia, NE China, in order to identify the paleoposition of the North China and Songliao‐Xilinhot blocks during Permo‐Carboniferous times and thereby define the spatial‐temporal history of the eastern Paleo‐Asian Ocean (PAO). Two prefolding magnetization components were isolated from the Sanmianjing and Elitu Formations (~283–266 Ma) along the northern margin of North China block (NMNCB) and the Dashizhai Formation (~280 Ma) in the Songliao‐Xilinhot block (SXB). These two results suggest paleolatitudes of ~4.9°N for the SXB and ~22.3°N for the NMNCB. Previously published results are classified according to recently proposed models and evaluated for the influence of inclination shallowing. Combined with earlier multidisciplinary studies, we propose a tentative paleogeographic reconstruction model for the eastern Central Asian Orogenic Belt (CAOB) during the Late Carboniferous to Early Triassic times. Siberia was situated at middle‐high paleolatitudes (~45°–65°N), and the Central Mongolia‐Erguna and South Mongolia‐Xing'an blocks had a middle latitude (~30°–45°N) from the Late Carboniferous to Early Permian. By the Late Permian to Early Triassic (~250 Ma), there was no significant latitudinal difference between the eastern CAOB blocks. Final closure of the eastern PAO along both the Hegenshan‐Heihe and Solonker sutures took place followed by the formation of Cinamuria.
Downscaling‐Based Segmentation for Unresolved Images of Highly Heterogeneous Granular Porous Samples
Authors: Korneev S. V. , Yang X. , Zachara J. M. , Scheibe T. D. , Battiato I.
Published: March 2018

Numerical simulations of pore‐scale flow and transport in natural sediments require the knowledge of pore‐space topology. Limited resolution of X‐ray tomography is often insufficient to fully characterize pore‐space structure within fine‐grained regions. Single and multilevel threshold‐based segmentation approaches are customarily employed to identify solid, pore and porous‐solid regions by means of grey intensity thresholds. While the choice of cutoff thresholds is often arbitrary, it dramatically affects the effective properties and the dynamical response of the reconstructed porous structure. We propose an algorithm of downscaling, i.e., the process of increasing image resolution, followed by segmentation, i.e., the identification of different phases, to reconstruct the unresolved pore‐space from XCT images of natural geological porous media. The method, applicable to moderately unresolved, chemically homogeneous granular media, is based on a map between local pixel porosity and pore size that does not rely on the definition of arbitrary thresholds and it allows to generate a high‐resolution binary image of the porous medium from poorly resolved grey‐scale images. First, we validate the method on synthetic unresolved images and compare their known pore‐space distribution with the extracted one. Then, we consider a synthetic porous medium and compare the pore size distribution, conductivity, and tortuosity between the original and the reconstructed structures. Finally, we apply the method to extract the pore‐space distribution from unresolved XCT images of two natural sediment columns and use it (i) to parametrize a capillary‐bundle model and (ii) to estimate the hydraulic conductivity by matching breakthrough behavior of passive solute transport.
Quantitative analysis of image quality for acceptance and commissioning of an MRI simulator with a semiautomatic method
Authors: Chen Xinyuan , Dai Jianrong
Published: March 2018

Magnetic Resonance Imaging (MRI) simulation differs from diagnostic MRI in purpose, technical requirements, and implementation. We propose a semiautomatic method for image acceptance and commissioning for the scanner, the radiofrequency (RF) coils, and pulse sequences for an MRI simulator. The ACR MRI accreditation large phantom was used for image quality analysis with seven parameters. Standard ACR sequences with a split head coil were adopted to examine the scanner's basic performance. The performance of simulation RF coils were measured and compared using the standard sequence with different clinical diagnostic coils. We used simulation sequences with simulation coils to test the quality of image and advanced performance of the scanner. Codes and procedures were developed for semiautomatic image quality analysis. When using standard ACR sequences with a split head coil, image quality passed all ACR recommended criteria. The image intensity uniformity with a simulation RF coil decreased about 34% compared with the eight‐channel diagnostic head coil, while the other six image quality parameters were acceptable. Those two image quality parameters could be improved to more than 85% by built‐in intensity calibration methods. In the simulation sequences test, the contrast resolution was sensitive to the FOV and matrix settings. The geometric distortion of simulation sequences such as T1‐weighted and T2‐weighted images was well‐controlled in the isocenter and 10 cm off‐center within a range of ±1% (2 mm). We developed a semiautomatic image quality analysis method for quantitative evaluation of images and commissioning of an MRI simulator. The baseline performances of simulation RF coils and pulse sequences have been established for routine QA.
The effect of biased lineup instructions on eyewitness identification confidence
Authors: Charman Steve D. , Carol Rolando N. , Schwartz Shari L.
Published: March 2018

Although it is well‐known that biased lineup instructions (i.e., those that do not inform witnesses the perpetrator may not be in the lineup) inflate false identifications, their effects on witness confidence are less well understood due to methodological limitations of past studies. We report two studies that use novel methodologies to obviate these limitations. Study 1 (N = 177) demonstrated that biased lineup instructions increased witnesses' average estimates of the likelihood that a lineup member is guilty. Study 2 (N = 137) introduces a novel debiasing paradigm that allows a parsing of choosers into those who made an identification only because of the biased instructions (induced choosers), and those who would have chosen despite the instructions (inherent choosers). Biased lineup instructions inflated confidence only among induced choosers, but not among inherent choosers. Contrary to legal reasoning, witness confidence is an insufficient metric to determine the suggestiveness of biased instructions.
An Ultralight Graphene Honeycomb Sandwich for Stretchable Light‐Emitting Displays
Authors: Wang Zhenyu , Liu Xu , Shen Xi , Han Ne Myo , Wu Ying , Zheng Qingbin , Jia Jingjing , Wang Ning , Kim Jang‐Kyo
Published: March 2018

Materials that can simultaneously achieve excellent electrical conductivity and stretchability are essential components for the next‐generation stretchable electronics. Herein, a highly conductive and stretchable graphene honeycomb (GHC) sandwich consisting of a porous GHC/polydimethylsiloxane (PDMS) composite core and ultrahigh‐density graphene foam/PDMS composite face sheets is rationally assembled. The GHCs prepared by a 3D printing technique possess a long‐range ordered hexagonal porous structure with an ultralow density of 3.25 mg cm−3 and deliver an excellent electrical conductivity of 72 S m−1. To the best of authors' knowledge, they are the lightest honeycomb structure reported in open literature. The highly porous GHC core endows the sandwich with an ultralow resistance change over large external strains of 60% with excellent structural durability. A stretchable light‐emitting display is demonstrated using the sandwich as the electric circuit and light‐emitting diodes as the pixels, which exhibits reliable lighting performance under different loading conditions.
Cubic‐Like Bimolecular Crystal Evolution and over 12% Efficiency in Halogen‐Free Ternary Solar Cells
Authors: Kumari Tanya , Lee Sang Myeon , Yang Changduk
Published: March 2018

In this study, the solubility properties of a given ternary blend set, with two donors (poly(4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo[1,2‐b;4,5‐b′]dithiophene‐2,6‐diyl‐alt‐(4‐(2‐ethylhexyl)‐3‐fluorothieno[3,4‐b]thiophene‐)‐2‐carboxylate‐2‐6‐diyl (PTB7‐Th) and benzo[1,2‐b;4,5‐b′]dithiophene‐based small molecule (DR3TSBDT)) and one acceptor ([6,6]‐phenyl‐C71‐butyric acid methyl ester (PC71BM)), in a series of solvents are determined, and active material–solvent interactions are used as an aid for finding suitable nonchlorinated solvents to achieve effective ternary organic solar cells (OSCs) based on PTB7‐Th:DR3TSBDT:PC71BM. An exceptional power conversion efficiency (PCE) as high as 12.3% (certified 11.94%) is obtained using the developed nonhalogenated processing system. In‐depth investigations (morphology, charge mobility, recombination dynamics, and OSC characteristics) uncover the underlying structure–property relationships as a function of the chosen nonhalogenated systems. Another intriguing finding of this study is the formation of a cubic bimolecular crystal structure of PTB7‐Th:PC71BM in a nonhalogenated system, which is the first such demonstration in blend films. This sheds light upon the fact that the physical properties of a material applied from different solutions may surpass the variation in the properties between two material having totally different molecular structure. Therefore, this work not only offers important scientific insights into developing highly efficient and eco‐friendly OSCs but also improves our understanding of achievable bimolecular crystals with an intercalated structure.
Toward High Performance Lithium–Sulfur Batteries Based on Li2S Cathodes and Beyond: Status, Challenges, and Perspectives
Authors: Su Dawei , Zhou Dong , Wang Chengyin , Wang Guoxiu
Published: March 2018

Lithium sulfur (Li–S) batteries are attracting ever‐increasing interests as a new generation rechargeable battery system with high energy density and low cost. Li–S batteries will fulfill their theoretical potential if the problem of polysulfides shuttle effect can be solved. Therefore, tremendous efforts have been devoted to overcoming this problem from the aspects of physical confinement and chemisorption of polysulfides. Recently, it is discovered that replacing sulfur cathodes with lithium sulfide (Li2S) can not only largely avoid the volume expansion issue during cycling, but it can also work with anode materials other than lithium metal to eliminate serious safety concerns for traditional Li–S batteries. However, there are many challenges for developing practical Li metal‐free Li–S battery systems, because Li2S‐based cathode materials are moisture‐sensitive and prelithiation of the non‐Li metal anode materials is usually required for practical applications. This study reviews the recent advances of Li‐S batteries based on Li2S cathode with features of improved safety, high Coulombic efficiency, and high energy density. The electrode activation processes are also discussed, which is critical for achieving high performances. It is anticipated that the extensive efforts will lead to breakthroughs for the development of Li2S cathode ‐based Li‐S batteries.
Bioinspired Micropatterned Superhydrophilic Au‐Areoles for Surface‐Enhanced Raman Scattering (SERS) Trace Detection
Authors: Li Huizeng , Yang Qiang , Hou Jue , Li Yanan , Li Mingzhu , Song Yanlin
Published: March 2018

Surface‐enhanced Raman scattering (SERS) provides an approach for the label‐free and miniaturized detection of the trace amount of analyte molecules. A SERS microchip of Au‐areoles array, mimicking the areole on the cactus, is facilely and controllably prepared through selectively electrochemical deposition on patterned superhydrophilic–superhydrophobic substrates. The Au‐areoles are full of SERS hot spots thanks to the large amounts of sharp edges, tips, and coupled branches. Meanwhile, the superhydrophilic sites on the superhydrophobic substrate can collect the target molecules into those hot spots. The combination of the SERS enhancement of the nanostructured‐Au and the collective effect of the superhydrophilic–superhydrophobic pattern endows the microchip with sample‐effective, ultrasensitive, and efficient Raman detection capabilities, which are demonstrated by integrated detection of femtomol Rhodamine 6G and diverse bioanalytes. The chip can also be used for mutually independent multisample detection without interference.
Dual Physical Crosslinking Strategy to Construct Moldable Hydrogels with Ultrahigh Strength and Toughness
Authors: Cao Jinfeng , Li Jiahong , Chen Yumei , Zhang Lina , Zhou Jinping
Published: March 2018

A dual physical crosslinking (DPC) strategy is used to construct moldable hydrogels with ultrahigh strength and toughness. First, polyelectrolyte complex (PEC) hydrogels are prepared through the in situ polymerization of acrylic acid monomers in the concentrated chitosan (Ch) solutions. Subsequently, Ag+ ions are introduced into the PEC hydrogels to form coordination bonds between NH2 and COOH groups. High‐density electrostatic interaction and coordination bonds endow the DPC hydrogels with high strength and toughness. The mechanical properties of the DPC hydrogels strongly depend on the weight ratio of Ch to poly(acrylic acid) and the loading concentration of Ag+ ions. When the loading concentration of Ag+ ions is in the range of 1.0–1.5 mol L−1, DPC 0.10–0.25 hydrogels display the maximum tensile strength (24.0 MPa) and toughness (84.7 MJ m−3) with a strain of more than 600%. Specially, the DPC hydrogels display an excellent moldable behavior due to the reversible properties of the electrostatic interaction and coordination bonds. The DPC strategy can also be applied in various other systems and opens a new avenue to fabricate hydrogels with outstanding mechanical properties and antibacterial activities.
Functional, RF‐Trilayer Sensors for Tooth‐Mounted, Wireless Monitoring of the Oral Cavity and Food Consumption
Authors: Tseng Peter , Napier Bradley , Garbarini Logan , Kaplan David L. , Omenetto Fiorenzo G.
Published: March 2018

Wearable devices have emerged as powerful tools for personalized healthcare in spite of some challenges that limit their widespread applicability as continuous monitors of physiological information. Here, a materials‐based strategy to add utility to traditional dielectric sensors by developing a conformal radiofrequency (RF) construct composed of an active layer encapsulated between two reverse‐facing split ring resonators is applied. These small (down to 2 mm × 2 mm) passive dielectric sensors possess enhanced sensitivity and can be further augmented by functionalization of this interlayer material. Demonstrator devices are shown where the interlayer is: (i) a porous silk film, and (ii) a modified PNIPAM hydrogel that swells with pH or temperature. In vivo use is demonstrated by adhesion of the device on tooth enamel to detect foods during human ingestion. Such sensors can be easily multiplexed and yield data‐rich temporal information during the diffusion of analytes within the trilayer structure. This format could be extended to a suite of interlayer materials for sensing devices of added use and specificity.
Self‐Reporting Fiber‐Reinforced Composites That Mimic the Ability of Biological Materials to Sense and Report Damage
Authors: Rifaie‐Graham Omar , Apebende Edward A. , Bast Livia K. , Bruns Nico
Published: March 2018

Sensing of damage, deformation, and mechanical forces is of vital importance in many applications of fiber‐reinforced polymer composites, as it allows the structural health and integrity of composite components to be monitored and microdamage to be detected before it leads to catastrophic material failure. Bioinspired and biomimetic approaches to self‐sensing and self‐reporting materials are reviewed. Examples include bruising coatings and bleeding composites based on dye‐filled microcapsules, hollow fibers, and vascular networks. Force‐induced changes in color, fluorescence, or luminescence are achieved by mechanochromic epoxy resins, or by mechanophores and force‐responsive proteins located at the interface of glass/carbon fibers and polymers. Composites can also feel strain, stress, and damage through embedded optical and electrical sensors, such as fiber Bragg grating sensors, or by resistance measurements of dispersed carbon fibers and carbon nanotubes. Bioinspired composites with the ability to show autonomously if and where they have been damaged lead to a multitude of opportunities for aerospace, automotive, civil engineering, and wind‐turbine applications. They range from safety features for the detection of barely visible impact damage, to the real‐time monitoring of deformation of load‐bearing components.
Contact‐Engineered Electrical Properties of MoS2 Field‐Effect Transistors via Selectively Deposited Thiol‐Molecules
Authors: Cho Kyungjune , Pak Jinsu , Kim Jae‐Keun , Kang Keehoon , Kim Tae‐Young , Shin Jiwon , Choi Barbara Yuri , Chung Seungjun , Lee Takhee
Published: March 2018

Although 2D molybdenum disulfide (MoS2) has gained much attention due to its unique electrical and optical properties, the limited electrical contact to 2D semiconductors still impedes the realization of high‐performance 2D MoS2‐based devices. In this regard, many studies have been conducted to improve the carrier‐injection properties by inserting functional paths, such as graphene or hexagonal boron nitride, between the electrodes and 2D semiconductors. The reported strategies, however, require relatively time‐consuming and low‐yield transfer processes on sub‐micrometer MoS2 flakes. Here, a simple contact‐engineering method is suggested, introducing chemically adsorbed thiol‐molecules as thin tunneling barriers between the metal electrodes and MoS2 channels. The selectively deposited thiol‐molecules via the vapor‐deposition process provide additional tunneling paths at the contact regions, improving the carrier‐injection properties with lower activation energies in MoS2 field‐effect transistors. Additionally, by inserting thiol‐molecules at the only one contact region, asymmetric carrier‐injection is feasible depending on the temperature and gate bias.
Materials for Neural Differentiation, Trans‐Differentiation, and Modeling of Neurological Disease
Authors: Gong Lulu , Cao Lining , Shen Zhenmin , Shao Li , Gao Shaorong , Zhang Chao , Lu Jianfeng , Li Weida
Published: March 2018

Neuron regeneration from pluripotent stem cells (PSCs) differentiation or somatic cells trans‐differentiation is a promising approach for cell replacement in neurodegenerative diseases and provides a powerful tool for investigating neural development, modeling neurological diseases, and uncovering the mechanisms that underlie diseases. Advancing the materials that are applied in neural differentiation and trans‐differentiation promotes the safety, efficiency, and efficacy of neuron regeneration. In the neural differentiation process, matrix materials, either natural or synthetic, not only provide a structural and biochemical support for the monolayer or three‐dimensional (3D) cultured cells but also assist in cell adhesion and cell‐to‐cell communication. They play important roles in directing the differentiation of PSCs into neural cells and modeling neurological diseases. For the trans‐differentiation of neural cells, several materials have been used to make the conversion feasible for future therapy. Here, the most current applications of materials for neural differentiation for PSCs, neuronal trans‐differentiation, and neurological disease modeling is summarized and discussed.
Droplet Microarrays: From Surface Patterning to High‐Throughput Applications
Authors: Feng Wenqian , Ueda Erica , Levkin Pavel A.
Published: March 2018

High‐throughput screening of live cells and chemical reactions in isolated droplets is an important and growing method in areas ranging from studies of gene functions and the search for new drug candidates, to performing combinatorial chemical reactions. Compared with microfluidics and well plates, the facile fabrication, high density, and open structure endow droplet microarrays on planar surfaces with great potential in the development of next‐generation miniaturized platforms for high‐throughput applications. Surfaces with special wettability have served as substrates to generate and/or address droplets microarrays. Here, the formation of droplet microarrays with designed geometry on chemically prepatterned surfaces is briefly described and some of the newer and emerging applications of these microarrays that are currently being explored are highlighted. Next, some of the available technologies used to add (bio‐)chemical libraries to each droplet in parallel are introduced. Current challenges and future prospects that would benefit from using such droplet microarrays are also discussed.
Reconfigurable Printed Liquids
Authors: Forth Joe , Liu Xubo , Hasnain Jaffar , Toor Anju , Miszta Karol , Shi Shaowei , Geissler Phillip L. , Emrick Todd , Helms Brett A. , Russell Thomas P.
Published: March 2018

Liquids lack the spatial order required for advanced functionality. Interfacial assemblies of colloids, however, can be used to shape liquids into complex, 3D objects, simultaneously forming 2D layers with novel magnetic, plasmonic, or structural properties. Fully exploiting all‐liquid systems that are structured by their interfaces would create a new class of biomimetic, reconfigurable, and responsive materials. Here, printed constructs of water in oil are presented. Both form and function are given to the system by the assembly and jamming of nanoparticle surfactants, formed from the interfacial interaction of nanoparticles and amphiphilic polymers that bear complementary functional groups. These yield dissipative constructs that exhibit a compartmentalized response to chemical cues. Potential applications include biphasic reaction vessels, liquid electronics, novel media for the encapsulation of cells and active matter, and dynamic constructs that both alter, and are altered by, their external environment.
Textile Display for Electronic and Brain‐Interfaced Communications
Authors: Zhang Zhitao , Cui Liyuan , Shi Xiang , Tian Xiaochaoran , Wang Dongping , Gu Chunni , Chen Er , Cheng Xunliang , Xu Yifan , Hu Yajie , Zhang Jiayi , Zhou Lei , Fong Hon Hang , Ma Pibo , Jiang Gaoming , Sun Xuemei , Zhang Bo , Peng Huisheng
Published: March 2018

Textile displays are poised to revolutionize current electronic devices, and reshape the future of electronics and related fields such as biomedicine and soft robotics. However, they remain unavailable due to the difficulty of directly constructing electroluminescent devices onto the textile‐like substrate to really display desired programmable patterns. Here, a novel textile display is developed from continuous electroluminescent fibers made by a one‐step extrusion process. The resulting displaying textile is flexible, stretchable, three‐dimensionally twistable, conformable to arbitrarily curved skins, and breathable, and can dynamically display a series of desired patterns, making it useful for bioinspired electronics, soft robotics, and electroluminescent skins, among other applications. It is demonstrated that these displaying textiles can also communicate with a computer and mouse brain for smart display and camouflage applications. This work may open up a new direction for the integration of wearable electroluminescent devices with the human body, providing new and promising communication platforms.
Interfacial Self‐Assembly of Colloidal Nanoparticles in Dual‐Droplet Inkjet Printing
Authors: Al‐Milaji Karam Nashwan , Secondo Ray Richard , Ng Tse Nga , Kinsey Nathaniel , Zhao Hong
Published: March 2018

The well‐known coffee‐ring effect causes colloidal particles to convectively transport toward the contact line of an inkjet droplet leading to a nonuniform deposition of the colloidal particles. In this work, the self‐assembly of colloidal particles in a dual‐droplet inkjet printing configuration to produce a nearly monolayer closely packed deposition of colloidal particles that exhibits a colorful reflection are demonstrated. By controlling the ink surface tensions and jetting parameters, the wetting droplets (the second droplet) containing colloidal polystyrene (PS) nanoparticles quickly spread over the supporting droplets (the first droplet) upon impact. The well‐ordered deposition is achieved by tuning the solvent composition of the wetting droplets and functionalization of the PS nanoparticles to encourage a network formation among the colloidal particles at the air–droplet interface. The underlying self‐assembly mechanism is insensitive to substrates and can be applied to many other material/substrate combinations. Finally, the origin of the color generation is highlighted, and the potential of the dual‐droplet inkjet printing process is discussed for fabrication of optical devices.
Temperature‐Induced Atomic Reconstruction At Au/MgAl2O4 Interfaces
Authors: Liu Fang , Xie Dong Yue , Bugnet Matthieu , Majdi Tahereh , Preston John S. , Wang Jian , Zhu Guo‐zhen
Published: March 2018

The metal–oxide interaction, associated with intermingling delocalization of bonding electrons in metals and ionic bonds in oxides, may cause reconstruction of interface structure and accordingly affect physical properties of heterogeneous materials. This Communication reports reconstructions of (111) interface between gold and magnesium aluminate spinel according to experimental observation and theoretical prediction. Three interfacial structures are evidenced with respect to the arrangement of gold atoms: perfect Au (111) interface, atoms missing in the first Au (111) plane, and atoms mixing in the two adjacent atomic planes. Such atomic arrangements in the reconstructed interfaces are similar to those of metal cations in the spinel lattice, thus providing new insights into the chemistry and structure of metal–oxide interfaces and highlighting new pathways toward metal–oxide interface engineering.
Thermal Conductivity Reduction at Inorganic–Organic Interfaces: From Regular Superlattices to Irregular Gradient Layer Sequences
Authors: Krahl Fabian , Giri Ashutosh , Tomko John A. , Tynell Tommi , Hopkins Patrick E. , Karppinen Maarit
Published: March 2018

Nanoscale superlattice structures are known to significantly suppress the thermal conductivity in thin films due to phonon scattering at the interfaces of the mutually different layers. Here it is demonstrated that in addition to the number of interfaces, their spacing within the film can lead to a reduction in thermal conductivity. The proof‐of‐concept data are for ZnO/benzene thin films fabricated through sequential gas‐surface reactions in atomic/molecular layer precision using the atomic/molecular layer deposition technique. In comparison to similarly constructed regular superlattice thin films, thermal conductivity values that are of the same magnitude, or even lower, are achieved for hybrid ZnO/benzene thin films in which the inorganic and organic layers are arranged in a more irregular manner to form various gradient patterns.
Luminescence in 2D Materials and van der Waals Heterostructures
Authors: Jie Wenjing , Yang Zhibin , Bai Gongxun , Hao Jianhua
Published: March 2018

Due to the isolation and fabrication of a rapidly increasing number of 2D materials, extensive attention is drawn to investigate 2D materials for scientific and technological studies as well as potential applications. In recent years, a series of significant and fascinating properties have been found and further modified in graphene and graphene‐like 2D layered materials. Among them, luminescence is one of the important investigation aspects, which is relevant to the unique structural, carrier transport, photonic, and optoelectronic properties of 2D materials. Herein, a general overview of recent advances of luminescence in 2D systems, including 2D materials and van der Waals heterostructures, is given. This review article provides an insight into the mechanism of luminescence and the luminescent characterizations and performance as well as the methods employed to modulate the luminescence behaviors of 2D systems. A number of recent works are introduced to specifically describe the new developments of photoluminescence, electroluminescence, and nonlinear optics in 2D materials. Then, the applications of luminescence in 2D systems are discussed in terms of optoelectronics and biological fields. By summarizing the importance of luminescence in 2D materials and van der Waals heterostructures, the challenges and opportunities for future investigation and applications are highlighted.
Access to Amidines and Arylbenzimidazoles: Zinc‐Promoted Rearrangement of Oxime Acetates
Authors: Zhu Zhongzhi , Cen Jinghe , Tang Xiaodong , Li Jianxiao , Wu Wanqing , Jiang Huanfeng
Published: March 2018

An efficient and straightforward zinc‐promoted rearrangement of oxime acetates with arylamines for the synthesis of amidines has been developed under mild conditions. This process involves N−O/C−C bond cleavages and C−C/C−N bond formations. Various oxime acetates and arylamines are suitable for this transformation. Furthermore, diverse arylbenzimidazoles could also be prepared through simple one‐pot procedure.

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Asymmetric Nazarov Cyclizations Catalyzed by Chiral‐at‐Metal Complexes
Authors: Mietke Thomas , Cruchter Thomas , Larionov Vladimir A. , Faber Tabea , Harms Klaus , Meggers Eric
Published: March 2018

The application of Lewis acidic chiral‐at‐metal complexes of iridium(III) and rhodium(III) as catalysts for the asymmetric polarized Nazarov cyclization of dihydropyran‐ and indole‐functionalized α‐unsaturated β‐ketoesters is reported (overall 24 examples). For both substrate classes, catalyst loadings of 2 mol% were found to be sufficient for achieving high yields and high stereoselectivities. The cyclized dihydropyran products were isolated in 85–98% yield, with 89%–>99% ee, and trans/cis ratios of 15:1–50:1 (9 examples). The cyclized indole products were typically isolated in more than 70% yield and in up to 93% yield, typically with more than 90% ee and in up to 97% ee, and trans/cis ratios of 12:1–28:1 (15 examples).

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Enantioselective Construction of Spiro Thiazol‐4‐one Derivatives with Multiple Stereocenters via an Organocatalyzed Multicomponent Cascade Reaction
Authors: Xiao Yuanyuan , Jiang Rongrong , Wang Youming , Zhou Zhenghong
Published: March 2018

We have developed an organocatalyzed asymmetric three‐component reaction of thiazol‐4‐ones, acrolein and nitroolefins, which provides an efficient approach to access optically active spiro thiazol‐4‐ones. Under the catalysis of a bifunctional squaramide derived from L‐tert‐leucine, the reactions of a wide range of thiazol‐4‐ones, acrolein and nitroolefins took place smoothly to generate the corresponding spirothiazolone derivatives bearing four contiguous stereogenic centers in good yields with high levels of enantioselectivity. The title chiral spirothiazolones were obtained as a pair of separable epimers, which are formed through a double Michael addition followed by a Henry process.

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PhIO/Et3N ⋅ 3HF‐Mediated Formation of Fluorinated 2H‐Azirines via Domino Fluorination/Azirination Reaction of Enamines
Authors: Zhang Yong , Zhao Xiaoyuan , Zhuang Chen , Wang Senlin , Zhang‐Negrerie Daisy , Du Yunfei
Published: March 2018

A variety of enamine carboxylic esters and enaminones were converted to the biologically interesting fluorinated 2H‐azirines through reactions with PhIF2 generated in situ by PhIO and Et3N ⋅ 3HF in 1,2‐dichroloethane, which features the hypervalent iodine reagents‐mediated introduction of fluorine atom and formation of the 2H‐azirine skeleton under metal‐free conditions. The domino reaction is postulated to proceed via a PhIF2‐mediated oxidative fluorination and a subsequent azirination of the fluorinated enamine intermediates.

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Direct Aryl‐Aryl Coupling without Pre‐Functionalization Enabled by Excessive Oxidation of Two‐Electron Ag(I)/Ag(III) Catalyst
Authors: Singh Ajay K. , Kim Min‐Gyu , Lee Hyune‐Jea , Singh Rakhi , Cho Seung Hwan , Kim Dong‐Pyo
Published: March 2018

Reported herein is a catalytic platform for formation of unsymmetrical biaryls by the coupling between inert Csp2−CH3 and Csp2−H via a tandem catalytic strategy. The platform utilizes traditional AgNO3 catalyst and excess amount of K2S2O8 oxidant. The excessive oxidant present converts the traditional one‐electron Ag(I)/Ag(II) chemistry to two‐electron Ag(I)/Ag(III) one, enabling one‐pot synthesis of aryl‐aryl scaffolds by using unactivated cheap commodity chemicals.

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Origin of Temperature‐Dependent Ferroelectricity in Si‐Doped HfO2
Authors: Park Min Hyuk , Chung Ching‐Chang , Schenk Tony , Richter Claudia , Hoffmann Michael , Wirth Steffen , Jones Jacob L. , Mikolajick Thomas , Schroeder Uwe
Published: March 2018

The structural origin of the temperature‐dependent ferroelectricity in Si‐doped HfO2 thin films is systematically examined. From temperature‐dependent polarization‐electric field measurements, it is shown that remanent polarization increases with decreasing temperature. Concurrently, grazing incidence X‐ray diffraction shows an increase in the orthorhombic phase fraction with decreasing temperature. The temperature‐dependent evolution of structural and ferroelectric properties is believed to be highly promising for the electrocaloric cooling application. Magnetization measurements do not provide any indication for a change of magnetization within the temperature range for the strong crystalline phase transition, suggesting that magnetic and structural properties are comparatively decoupled. The results are believed to provide the first direct proof of the strongly coupled evolution of structural and electrical properties with varying temperature in fluorite oxide ferroelectrics.
Flexible, Scalable, and Highly Conductive Garnet‐Polymer Solid Electrolyte Templated by Bacterial Cellulose
Authors: Xie Hua , Yang Chunpeng , Fu Kun (Kelvin) , Yao Yonggang , Jiang Feng , Hitz Emily , Liu Boyang , Wang Sha , Hu Liangbing
Published: March 2018

Solid‐state electrolytes are a promising candidate for the next‐generation lithium‐ion battery, as they have the advantages of eliminating the leakage hazard of liquid solvent and elevating stability. However, inherent limitations such as the low ionic conductivity of solid polymer electrolytes and the high brittleness of inorganic ceramic electrolytes severally impede their practical application. Here, an inexpensive, facile, and scalable strategy to fabricate a hybrid Li7La3Zr2O12 (LLZO) and poly(ethylene oxide)‐based electrolyte by exploiting bacterial cellulose as a template is reported. The well‐organized LLZO network significantly enhances the ionic conductivity by extending long transport pathways for Li ions, exhibiting an elevated conductivity of 1.12 × 10−4 S cm−1. In addition, the hybrid electrolyte presents a structural flexibility, with minor impedance increase after bending. The facile and applicable approach establishes new principles for the strategy of designing scalable and flexible hybrid polymer electrolytes that can be utilized for high‐energy‐density batteries.
Examining the relationship between vertical coordination strategies and technical efficiency: Evidence from the Brazilian ethanol industry
Authors: Sant'Anna Ana Claudia , Bergtold Jason S. , Shanoyan Aleksan , Granco Gabriel , Caldas Marcellus M.
Published: March 2018

The sugarcane industry in Brazil, one of the world's leading producers of ethanol and sugar, is undergoing significant changes driven by geographic expansion and technological innovations. These changes are forcing sugarcane producers and processors, to re‐evaluate their vertical coordination and growth strategies. This paper presents an empirical analysis of the relationship between the vertical coordination strategies at the production‐processing interface of the Brazilian ethanol supply chain and the technical efficiency of the mills. It utilizes data envelopment analysis and a Tobit censored model in combination with unique data on 204 mills that account for around half of Brazil's sugar and ethanol production. Results indicate that vertical integration and the location of the mill have a statistically significant impact on efficiency. The findings show that the technical efficiency is not the main driver of vertical integration implying that such decisions are primarily motivated by strategic considerations. The mills are likely to forgo gains in technical efficiency in exchange for improving their strategic position through vertical integration. These findings shed light on the underlying motivation for the observed level of vertical integration that accompanies the expansion of the Brazilian sugarcane industry. [EconLit citations: L22, Q12, Q16].
Trait differences in responses to arbuscular mycorrhizal fungi are stronger and more consistent than fixed differences among populations of Asclepias speciosa
Authors: Waller Lauren P. , Hahn Philip G. , Maron John L. , Lekberg Ylva
Published: March 2018

Premise of the Study

Arbuscular mycorrhizal (AM) fungi can promote plant growth and reproduction, but other plant physiological traits or traits that provide defense against herbivores can also be affected by AM fungi. However, whether responses of different traits to AM fungi are correlated and whether these relationships vary among plants from different populations are unresolved.

Methods

In a common garden experiment, we grew Asclepias speciosa plants from seed collected from populations found along an environmental gradient with and without AM fungi to assess whether the responses of six growth and defense traits to AM fungi are correlated.

Key Results

Although there was strong genetic differentiation in mean trait values among populations, AM fungi consistently increased expression of most growth and defense traits across all populations. Responses of biomass and root to shoot ratio to AM fungi were positively correlated, suggesting that plants that are more responsive to AM fungi allocated more biomass belowground. Responses of biomass and trichome density to AM fungi were negatively correlated, indicating a trade‐off in responsiveness between a growth and defensive trait.

Conclusions

Our results suggest that while there is substantial population differentiation in many traits of A. speciosa, populations respond similarly to AM fungi, and both positive and negative correlations among trait responses occur.
A Copper‐Catalyzed Domino Reaction of Alkynyl Bromides and Oxazolidine‐2‐thiones: Synthesis of Thiazol‐2‐ones
Authors: Xie Chunsong , Zhang Yuhong
Published: March 2018

A copper‐catalyzed cyclization of alkynyl bromides and oxazolidine‐2‐thiones is described. C−N and C−S bonds are simultaneously constructed and a multi‐step process occurred to give the five‐member heterocycles of thiazol‐2‐ones containing 2‐alkylthio‐oxazolines. Optically active oxazolidine‐2‐thiones undergo the cyclization with complete retention of configuration.
Optogenetic Control of Voltage‐Gated Calcium Channels
Authors: Ma Guolin , Liu Jindou , Ke Yuepeng , Liu Xin , Li Minyong , Wang Fen , Han Gang , Huang Yun , Wang Youjun , Zhou Yubin
Published: March 2018

Voltage‐gated Ca2+ (CaV) channels mediate Ca2+ entry into excitable cells to regulate a myriad of cellular events following membrane depolarization. We report the engineering of RGK GTPases, a class of genetically encoded CaV channel modulators, to enable photo‐tunable modulation of CaV channel activity in excitable mammalian cells. This optogenetic tool (designated optoRGK) tailored for CaV channels could find broad applications in interrogating a wide range of CaV‐mediated physiological processes.
In‐situ‐Untersuchungen mechanochemischer Eintopfreaktionen
Authors: Kulla Hannes , Haferkamp Sebastian , Akhmetova Irina , Röllig Mathias , Maierhofer Christiane , Rademann Klaus , Emmerling Franziska
Published: March 2018

Zur Untersuchung von Mahlreaktionen in Echtzeit wurden drei analytische Methoden gekoppelt: Synchrotron‐Röntgenbeugung mit Raman‐Spektroskopie und Thermographie. Diese Methodenkombination ermöglicht es, die strukturelle Entwicklung mit Temperaturinformationen zu korrelieren. Die Temperaturinformation ist entscheidend für das Verständnis von Thermodynamik und Reaktionskinetik. Exemplarisch wurde der Reaktionsmechanismus von drei mechanochemischen Modell‐Synthesen, einer Cokristallbildung, einer C‐C‐Bindungsknüpfung (Knoevenagel‐Kondensation) und der Bildung einer metallorganischen Verbindung, eines Mangan‐Phosphonats, aufgeklärt. Allgemeine Trends bezüglich der Temperaturentwicklung beim Mahlen konnten identifiziert werden. Die Reaktions‐ und Kristallisationswärme tragen zur gesamten Temperaturerhöhung bei. Eine Erniedrigung der Temperatur tritt bei Freisetzung von z. B. Wasser als Nebenprodukt auf. Die drei unabhängigen Methoden ergänzen sich gegenseitig, wodurch der Informationsgewinn maximiert und der Nachweis fester sowie flüssiger Intermediate ermöglicht wird. Schließlich konnte der Einfluss der mechanischen Einwirkung von den durch die Reaktion hervorgerufenen Temperatureinflüssen unterschieden werden.
Concerted Catalysis by Adjacent Palladium and Gold in Alloy Nanoparticles for the Versatile and Practical [2+2+2] Cycloaddition of Alkynes
Authors: Miura Hiroki , Tanaka Yumi , Nakahara Karin , Hachiya Yuka , Endo Keisuke , Shishido Tetsuya
Published: March 2018

A Pd‐Au alloy efficiently catalyzed the [2+2+2] cycloaddition of substituted alkynes. Whereas monometallic Pd and Au catalysts were totally ineffective, Pd‐Au alloy nanoparticle catalysts with a low Pd/Au molar ratio showed high activity to give the corresponding polysubstituted arenes in high yields. A variety of substituted alkynes participated in various modes of cycloaddition under Pd‐Au alloy catalysis. The Pd‐Au alloy catalysts exhibited high air tolerance and reusability.
Die chemischen Grundlagen der Adhäsion von Catechol
Authors: Saiz‐Poseu J. , Mancebo‐Aracil J. , Nador F. , Busqué F. , Ruiz‐Molina D.
Published: March 2018

Die Anhaftung einiger mariner Organismen in nasser Umgebung an fast jede Art von Oberfläche hat in den letzten Jahrzehnten zunehmendes Interesse geweckt. Zahlreiche Untersuchungen wurden durchgeführt, um die Grundlage für dieses Verhalten zu verstehen. Dabei wurde festgestellt, dass Catechol eine Schlüsselrolle spielt. Mithilfe des Wissens aus diesen Studien wurden einige neuartige bioinspirierte Klebstoffe und Beschichtungen mit zusätzlichem Nutzen entwickelt. Bisher gab es noch keine detaillierte Zusammenstellung, die sich ausschließlich auf die komplexe innere Funktionsweise dieser Materialien konzentrierte. Dieser Aufsatz befasst sich daher mit aktuellen Untersuchungen, die den Ursprung der Adsorptionskapazität von Catechol‐Derivaten und die Effekte von äußeren Faktoren aufklären, die wichtige Rollen im Gesamtprozess der Adhäsion spielen, z. B pH‐Wert, Lösungsmittel und Metallionen. Er beleuchtet die Details der Chemie, die für die erstaunlichen Eigenschaften Catechol‐haltiger adhäsiver Materialien verantwortlich sind.
Combined In Situ Illumination‐NMR‐UV/Vis Spectroscopy: A New Mechanistic Tool in Photochemistry
Authors: Seegerer Andreas , Nitschke Philipp , Gschwind Ruth M.
Published: March 2018

Synthetic applications in photochemistry are booming. Despite great progress in the development of new reactions, mechanistic investigations are still challenging. Therefore, we present a fully automated in situ combination of NMR spectroscopy, UV/Vis spectroscopy, and illumination to allow simultaneous and time‐resolved detection of paramagnetic and diamagnetic species. This optical fiber‐based setup enables the first acquisition of combined UV/Vis and NMR spectra in photocatalysis, as demonstrated on a conPET process. Furthermore, the broad applicability of combined UVNMR spectroscopy for light‐induced processes is demonstrated on a structural and quantitative analysis of a photoswitch, including rate modulation and stabilization of transient species by temperature variation. Owing to the flexibility regarding the NMR hardware, temperature, and light sources, we expect wide‐ranging applications of this setup in various research fields.