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  • Flexible and Electrically Tunable Plasmons in Graphene–Mica Heterostructures
    Adv. Sci. (IF 9.034) Pub Date : 2018-06-16
    Hai Hu; Xiangdong Guo; Debo Hu; Zhipei Sun; Xiaoxia Yang; Qing Dai
    更新日期:2018-06-17
  • Electrochemical Analysis of the Carbon-Encapsulated Lithium Iron Phosphate Nanochains and Their High-Temperature Conductivity Profiles
    ACS Omega Pub Date : 2018-06-15
    K. P. Abhilash, P. Christopher Selvin, B. Nalini, Hui Xia, Stefan Adams, M. V. Reddy
    更新日期:2018-06-16
  • Role of the Surface Nanoscale Roughness of Stainless Steel on Bacterial Adhesion and Microcolony Formation
    ACS Omega Pub Date : 2018-06-15
    Songmei Wu, Stefanie Altenried, Andi Zogg, Flavia Zuber, Katharina Maniura-Weber, Qun Ren
    更新日期:2018-06-16
  • Oxygen-deficient triple perovskites as highly active and durable bifunctional electrocatalysts for oxygen electrode reactions
    Sci. Adv. Pub Date : 2018-06-01
    Nam-In Kim, Young Jin Sa, Tae Sup Yoo, Sung Ryul Choi, Rana Arslan Afzal, Taekjib Choi, Young-Soo Seo, Kug-Seung Lee, Jun Yeon Hwang, Woo Seok Choi, Sang Hoon Joo, Jun-Young Park

    Highly active and durable bifunctional oxygen electrocatalysts have been of pivotal importance for renewable energy conversion and storage devices, such as unitized regenerative fuel cells and metal-air batteries. Perovskite-based oxygen electrocatalysts have emerged as promising nonprecious metal bifunctional electrocatalysts, yet their catalytic activity and stability still remain to be improved. We report a high-performance oxygen electrocatalyst based on a triple perovskite, Nd1.5Ba1.5CoFeMnO9−δ (NBCFM), which shows superior activity and durability for oxygen electrode reactions to single and double perovskites. When hybridized with nitrogen-doped reduced graphene oxide (N-rGO), the resulting NBCFM/N-rGO catalyst shows further boosted bifunctional oxygen electrode activity (0.698 V), which surpasses that of Pt/C (0.801 V) and Ir/C (0.769 V) catalysts and which, among the perovskite-based electrocatalysts, is the best activity reported to date. The superior catalytic performances of NBCFM could be correlated to its oxygen defect–rich structure, lower charge transfer resistance, and smaller hybridization strength between O 2p and Co 3d orbitals.

    更新日期:2018-06-16
  • Multifunctional structural design of graphene thermoelectrics by Bayesian optimization
    Sci. Adv. Pub Date : 2018-06-01
    Masaki Yamawaki, Masato Ohnishi, Shenghong Ju, Junichiro Shiomi

    Materials development often confronts a dilemma as it needs to satisfy multifunctional, often conflicting, demands. For example, thermoelectric conversion requires high electrical conductivity, a high Seebeck coefficient, and low thermal conductivity, despite the fact that these three properties are normally closely correlated. Nanostructuring techniques have been shown to break the correlations to some extent; however, optimal design has been a major challenge due to the extraordinarily large degrees of freedom in the structures. By taking graphene nanoribbons (GNRs) as a representative thermoelectric material, we carried out structural optimization by alternating multifunctional (phonon and electron) transport calculations and Bayesian optimization to resolve the trade-off. As a result, we have achieved multifunctional structural optimization with an efficiency more than five times that achieved by random search. The obtained GNRs with optimized antidots significantly enhance the thermoelectric figure of merit by up to 11 times that of the pristine GNR. Knowledge of the optimal structure further provides new physical insights that independent tuning of electron and phonon transport properties can be realized by making use of zigzag edge states and aperiodic nanostructuring. The demonstrated optimization framework is also useful for other multifunctional problems in various applications.

    更新日期:2018-06-16
  • Experimental benchmarking of quantum control in zero-field nuclear magnetic resonance
    Sci. Adv. Pub Date : 2018-06-01
    Min Jiang, Teng Wu, John W. Blanchard, Guanru Feng, Xinhua Peng, Dmitry Budker

    Demonstration of coherent control and characterization of the control fidelity is important for the development of quantum architectures such as nuclear magnetic resonance (NMR). We introduce an experimental approach to realize universal quantum control, and benchmarking thereof, in zero-field NMR, an analog of conventional high-field NMR that features less-constrained spin dynamics. We design a composite pulse technique for both arbitrary one-spin rotations and a two-spin controlled-not (CNOT) gate in a heteronuclear two-spin system at zero field, which experimentally demonstrates universal quantum control in such a system. Moreover, using quantum information–inspired randomized benchmarking and partial quantum process tomography, we evaluate the quality of the control, achieving single-spin control for 13C with an average fidelity of 0.9960(2) and two-spin control via a CNOT gate with a fidelity of 0.9877(2). Our method can also be extended to more general multispin heteronuclear systems at zero field. The realization of universal quantum control in zero-field NMR is important for quantum state/coherence preparation, pulse sequence design, and is an essential step toward applications to materials science, chemical analysis, and fundamental physics.

    更新日期:2018-06-16
  • Addressable metasurfaces for dynamic holography and optical information encryption
    Sci. Adv. Pub Date : 2018-06-01
    Jianxiong Li, Simon Kamin, Guoxing Zheng, Frank Neubrech, Shuang Zhang, Na Liu

    Metasurfaces enable manipulation of light propagation at an unprecedented level, benefitting from a number of merits unavailable to conventional optical elements, such as ultracompactness, precise phase and polarization control at deep subwavelength scale, and multifunctionalities. Recent progress in this field has witnessed a plethora of functional metasurfaces, ranging from lenses and vortex beam generation to holography. However, research endeavors have been mainly devoted to static devices, exploiting only a glimpse of opportunities that metasurfaces can offer. We demonstrate a dynamic metasurface platform, which allows independent manipulation of addressable subwavelength pixels at visible frequencies through controlled chemical reactions. In particular, we create dynamic metasurface holograms for advanced optical information processing and encryption. Plasmonic nanorods tailored to exhibit hierarchical reaction kinetics upon hydrogenation/dehydrogenation constitute addressable pixels in multiplexed metasurfaces. The helicity of light, hydrogen, oxygen, and reaction duration serve as multiple keys to encrypt the metasurfaces. One single metasurface can be deciphered into manifold messages with customized keys, featuring a compact data storage scheme as well as a high level of information security. Our work suggests a novel route to protect and transmit classified data, where highly restricted access of information is imposed.

    更新日期:2018-06-16
  • Nanoscale momentum-resolved vibrational spectroscopy
    Sci. Adv. Pub Date : 2018-06-01
    Fredrik S. Hage, Rebecca J. Nicholls, Jonathan R. Yates, Dougal G. McCulloch, Tracy C. Lovejoy, Niklas Dellby, Ondrej L. Krivanek, Keith Refson, Quentin M. Ramasse

    Vibrational modes affect fundamental physical properties such as the conduction of sound and heat and can be sensitive to nano- and atomic-scale structure. Probing the momentum transfer dependence of vibrational modes provides a wealth of information about a materials system; however, experimental work has been limited to essentially bulk and averaged surface approaches or to small wave vectors. We demonstrate a combined experimental and theoretical methodology for nanoscale mapping of optical and acoustic phonons across the first Brillouin zone, in the electron microscope, probing a volume ~1010 to 1020 times smaller than that of comparable bulk and surface techniques. In combination with more conventional electron microscopy techniques, the presented methodology should allow for direct correlation of nanoscale vibrational mode dispersions with atomic-scale structure and chemistry.

    更新日期:2018-06-16
  • Sequencing conjugated polymers by eye
    Sci. Adv. Pub Date : 2018-06-01
    Daniel A. Warr, Luís M. A. Perdigão, Harry Pinfold, Jonathan Blohm, David Stringer, Anastasia Leventis, Hugo Bronstein, Alessandro Troisi, Giovanni Costantini

    The solid-state microstructure of a conjugated polymer is the most important parameter determining its properties and performance in (opto)-electronic devices. A huge amount of research has been dedicated to tuning and understanding how the sequence of monomers, the nature and frequency of defects, the exact backbone conformation, and the assembly and crystallinity of conjugated polymers affect their basic photophysics and charge transporting properties. However, because of the lack of reliable high-resolution analytical techniques, all the structure-property relations proposed in the literature are based either on molecular modeling or on indirect experimental data averaged on polydisperse samples. We show that a combination of electrospray vacuum deposition and high-resolution scanning tunneling microscopy allows the imaging of individual conjugated polymers with unprecedented detail, thereby unraveling structural and self-assembly characteristics that have so far been impossible to determine.

    更新日期:2018-06-16
  • Stacking symmetry governed second harmonic generation in graphene trilayers
    Sci. Adv. Pub Date : 2018-06-01
    Yuwei Shan, Yingguo Li, Di Huang, Qingjun Tong, Wang Yao, Wei-Tao Liu, Shiwei Wu

    Crystal symmetry plays a central role in governing a wide range of fundamental physical phenomena. One example is nonlinear optical second harmonic generation (SHG), which requires inversion symmetry breaking. We report a unique stacking-induced SHG in graphene trilayers, whose individual monolayer sheet is centrosymmetric. Depending on layer stacking sequence, we observe a strong optical SHG in a Bernal ABA–stacked non-centrosymmetric trilayer, while it vanishes in a rhombohedral ABC–stacked one, which preserves inversion symmetry. This highly contrasting SHG due to the distinct stacking symmetry enables us to map out the ABA and ABC crystal domains in an otherwise homogeneous graphene trilayer. The extracted second-order nonlinear susceptibility of the ABA trilayer is surprisingly large, comparable to the best known two-dimensional semiconductors enhanced by excitonic resonance. Our results reveal a novel stacking order–induced nonlinear optical effect, as well as unleash the opportunity for studying intriguing physical phenomena predicted for stacking-dependent ABA and ABC graphene trilayers.

    更新日期:2018-06-16
  • MXenes stretch hydrogel sensor performance to new limits
    Sci. Adv. Pub Date : 2018-06-01
    Yi-Zhou Zhang, Kang Hyuck Lee, Dalaver H. Anjum, Rachid Sougrat, Qiu Jiang, Hyunho Kim, Husam N. Alshareef

    The development of wearable electronics, point-of-care testing, and soft robotics requires strain sensors that are highly sensitive, stretchable, capable of adhering conformably to arbitrary and complex surfaces, and preferably self-healable. Conductive hydrogels hold great promise as sensing materials for these applications. However, their sensitivities are generally low, and they suffer from signal hysteresis and fluctuation due to their viscoelastic property, which can compromise their sensing performance. We demonstrate that hydrogel composites incorporating MXene (Ti3C2Tx) outperform all reported hydrogels for strain sensors. The obtained composite hydrogel [MXene-based hydrogel (M-hydrogel)] exhibits outstanding tensile strain sensitivity with a gauge factor (GF) of 25, which is 10 times higher than that of pristine hydrogel. Furthermore, the M-hydrogel exhibits remarkable stretchability of more than 3400%, an instantaneous self-healing ability, excellent conformability, and adhesiveness to various surfaces, including human skin. The M-hydrogel composite exhibits much higher sensitivity under compressive strains (GF of 80) than under tensile strains. We exploit this asymmetrical strain sensitivity coupled with viscous deformation (self-recoverable residual deformation) to add new dimensions to the sensing capability of hydrogels. Consequently, both the direction and speed of motions on the hydrogel surface can be detected conveniently. Based on this effect, M-hydrogel demonstrates superior sensing performance in advanced sensing applications. Thus, the traditionally disadvantageous viscoelastic property of hydrogels can be transformed into an advantage for sensing, which reveals prospects for hydrogel sensors.

    更新日期:2018-06-16
  • Elastic properties of 2D Ti3C2Tx MXene monolayers and bilayers
    Sci. Adv. Pub Date : 2018-06-01
    Alexey Lipatov, Haidong Lu, Mohamed Alhabeb, Babak Anasori, Alexei Gruverman, Yury Gogotsi, Alexander Sinitskii

    Two-dimensional (2D) transition metal carbides and nitrides, known as MXenes, are a large class of materials that are finding numerous applications ranging from energy storage and electromagnetic interference shielding to water purification and antibacterial coatings. Yet, despite the fact that more than 20 different MXenes have been synthesized, the mechanical properties of a MXene monolayer have not been experimentally studied. We measured the elastic properties of monolayers and bilayers of the most important MXene material to date, Ti3C2Tx (Tx stands for surface termination). We developed a method for preparing well-strained membranes of Ti3C2Tx monolayers and bilayers, and performed their nanoindentation with the tip of an atomic force microscope to record the force-displacement curves. The effective Young’s modulus of a single layer of Ti3C2Tx was found to be 0.33 ± 0.03 TPa, which is the highest among the mean values reported in nanoindentation experiments for other solution-processed 2D materials, including graphene oxide. This work opens a pathway for investigating the mechanical properties of monolayers and bilayers of other MXenes and extends the already broad range of MXenes’ applications to structural composites, protective coatings, nanoresonators, and membranes that require materials with exceptional mechanical properties.

    更新日期:2018-06-16
  • Biomimetic enzyme cascade reaction system in microfluidic electrospray microcapsules
    Sci. Adv. Pub Date : 2018-06-01
    Huan Wang, Ze Zhao, Yuxiao Liu, Changmin Shao, Feika Bian, Yuanjin Zhao

    Mimicking subcellular compartments containing enzymes in organisms is considered a promising approach to substitute for missing or lost cellular functions. Inspired by the multicompartment structures of cellular architectures, we present a novel multienzyme system based on hollow hydrogel microcapsules with flexible enzymatic inverse opal particles. Benefiting from the precise operation capability of the microfluidic electrospray and the remarkable structural color marks in the inverse opal particles, we developed a multienzyme system with controllable number, type, and spatial arrangement of the encapsulated enzymes. The hydrogel shells also could improve enzyme stability against proteolysis in the system. The multienzyme system containing alcohol oxidase and catalase could act as a cascade biocatalyst and reduce alcohol levels in media, providing an alternative antidote and prophylactic for alcohol intoxication. These features indicated that our strategy provides an ideal enzyme cascade reaction system for complex biocatalysis and biomimetic functions of some organelles or organs.

    更新日期:2018-06-16
  • Ultra-confined mid-infrared resonant phonon polaritons in van der Waals nanostructures
    Sci. Adv. Pub Date : 2018-06-01
    Michele Tamagnone, Antonio Ambrosio, Kundan Chaudhary, Luis A. Jauregui, Philip Kim, William L. Wilson, Federico Capasso

    Hexagonal boron nitride has been proposed as an excellent candidate to achieve subwavelength infrared light manipulation owing to its polar lattice structure, enabling excitation of low-loss phonon polaritons with hyperbolic dispersion. We show that strongly subwavelength hexagonal boron nitride planar nanostructures can exhibit ultra-confined resonances and local field enhancement. We investigate strong light-matter interaction in these nanoscale structures via photo-induced force microscopy, scattering-type scanning near-field optical microscopy, and Fourier transform infrared spectroscopy, with excellent agreement with numerical simulations. We design optical nano-dipole antennas and directly image the fields when bright- or dark-mode resonances are excited. These modes are deep subwavelength, and strikingly, they can be supported by arbitrarily small structures. We believe that phonon polaritons in hexagonal boron nitride can play for infrared light a role similar to that of plasmons in noble metals at visible frequency, paving the way for a new class of efficient and highly miniaturized nanophotonic devices.

    更新日期:2018-06-16
  • A Novel On‐Chip Method for Differential Extraction of Sperm in Forensic Cases
    Adv. Sci. (IF 9.034) Pub Date : 2018-06-15
    Fatih Inci; Mehmet O. Ozen; Yeseren Saylan; Morteza Miansari; Duygu Cimen; Raghu Dhara; Thiruppathiraja Chinnasamy; Mehmet Yuksekkaya; Chiara Filippini; Deepan Kishore Kumar; Semih Calamak; Yusuf Yesil; Naside Gozde Durmus; George Duncan; Leonard Klevan; Utkan Demirci
    更新日期:2018-06-16
  • How to explain the AKT phosphorylation of downstream targets in the wake of recent findings [Letters (Online Only)]
    PNAS (IF 9.661) Pub Date : 2018-06-15
    Anil K. Agarwal

    AKT (v-Akt oncogene), a Ser/Thr protein kinase, was also identified as protein kinase B (PKB) (reviewed in ref. 1). There are three known isoforms of AKT1-3. All these AKT isoforms are highly conserved and are recruited to the plasma membrane where they bind to PIP3,4,5 via the PH-domain and are phosphorylated. While Lučić et al. (2) studied AKT1, the study is applicable to all of the AKT isoforms. Among the three AKT isoforms, AKT2 is extensively studied due to its critical role in insulin signaling (3). AKT is a central hub for cellular signal transduction, relaying information …

    更新日期:2018-06-16
  • Reply to Agarwal: Activity against nuclear substrates is not necessarily mediated by nuclear Akt [Letters (Online Only)]
    PNAS (IF 9.661) Pub Date : 2018-06-15
    Thomas A. Leonard

    The phosphorylation of Akt substrates in subcellular compartments other than the plasma membrane has previously been proposed to be mediated by the diffusion of activated Akt (1, 2). While this neatly accounts for the observation that Akt is activated by growth factors primarily at the plasma membrane, it poses problems for the cell in controlling the spatial and temporal dynamics of Akt substrate phosphorylation, since Akt would essentially be uncoupled from its activating stimulus. We recently showed that Akt activity is in fact confined to membranes enriched in either PI(3,4,5)P3 or PI(3,4)P2 (3, 4). By restricting Akt activity to the engagement …

    更新日期:2018-06-16
  • Breast cancer risk markedly lower with serum 25-hydroxyvitamin D concentrations ≥60 vs <20 ng/ml (150 vs 50 nmol/L): Pooled analysis of two randomized trials and a prospective cohort
    PLOS ONE (IF 2.806) Pub Date : 2018-06-15
    Sharon L. McDonnell, Carole A. Baggerly, Christine B. French, Leo L. Baggerly, Cedric F. Garland, Edward D. Gorham, Bruce W. Hollis, Donald L. Trump, Joan M. Lappe
    更新日期:2018-06-16
  • Development of a Hybrid Course on Wheelchair Service Provision for clinicians in international contexts
    PLOS ONE (IF 2.806) Pub Date : 2018-06-15
    Yohali Burrola-Mendez, Mary Goldberg, Rachel Gartz, Jon Pearlman
    更新日期:2018-06-16
  • Genome-wide characterization and expression analysis of citrus NUCLEAR FACTOR-Y (NF-Y) transcription factors identified a novel NF-YA gene involved in drought-stress response and tolerance
    PLOS ONE (IF 2.806) Pub Date : 2018-06-15
    Suzam L. S. Pereira, Cristina P. S. Martins, Aurizangela O. Sousa, Luciana R. Camillo, Caroline P. Araújo, Grazielle M. Alcantara, Danielle S. Camargo, Luciana C. Cidade, Alex-Alan F. de Almeida, Marcio G. C. Costa
    更新日期:2018-06-16
  • Bias due to differential and non-differential disease- and exposure misclassification in studies of vaccine effectiveness
    PLOS ONE (IF 2.806) Pub Date : 2018-06-15
    Tom De Smedt, Elizabeth Merrall, Denis Macina, Silvia Perez-Vilar, Nick Andrews, Kaatje Bollaerts
    更新日期:2018-06-16
  • Seasonal variations in Plasmodium falciparum parasite prevalence assessed by varying diagnostic tests in asymptomatic children in southern Ghana
    PLOS ONE (IF 2.806) Pub Date : 2018-06-15
    Ruth Ayanful-Torgby, Neils B. Quashie, Johnson N. Boampong, Kim C. Williamson, Linda E. Amoah
    更新日期:2018-06-16
  • Unraveling the Detailed Mechanism of Excited-State Proton Transfer
    Acc. Chem. Res. (IF 20.268) Pub Date : 2018-06-15
    Panwang Zhou, Keli Han
    更新日期:2018-06-16
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  • Evaluation of nutrient and energy sources of the deepest known serpentinite-hosted ecosystem using stable carbon, nitrogen, and sulfur isotopes
    PLOS ONE (IF 2.806) Pub Date : 2018-06-15
    Yuji Onishi, Toshiro Yamanaka, Tomoyo Okumura, Shinsuke Kawagucci, Hiromi Kayama Watanabe, Yasuhiko Ohara
    更新日期:2018-06-16
  • Modulating D-amino acid oxidase (DAAO) substrate specificity through facilitated solvent access
    PLOS ONE (IF 2.806) Pub Date : 2018-06-15
    Kalyanasundaram Subramanian, Artur Góra, Ruud Spruijt, Karolina Mitusińska, Maria Suarez-Diez, Vitor Martins dos Santos, Peter J. Schaap
    更新日期:2018-06-16
  • Reconciling species diversity in a tropical plant clade (Canarium, Burseraceae)
    PLOS ONE (IF 2.806) Pub Date : 2018-06-15
    Sarah Federman, Michael J. Donoghue, Douglas C. Daly, Deren A. R. Eaton
    更新日期:2018-06-16
  • Influence of elevated temperature on bovine oviduct epithelial cells (BOECs)
    PLOS ONE (IF 2.806) Pub Date : 2018-06-15
    Łukasz Rąpała, Rafał R. Starzyński, Piotr Z. Trzeciak, Sebastian Dąbrowski, Małgorzata Gajewska, Piotr Jurka, Roman Smolarczyk, Anna M. Duszewska
    更新日期:2018-06-16
  • Evidence for a second regulatory binding site on PspF that is occupied by the C-terminal domain of PspA
    PLOS ONE (IF 2.806) Pub Date : 2018-06-15
    Eyleen Sabine Heidrich, Thomas Brüser
    更新日期:2018-06-16
  • Changes in body composition, bone metabolism, strength, and skill-specific performance resulting from 16-weeks of HIFT
    PLOS ONE (IF 2.806) Pub Date : 2018-06-15
    Yuri Feito, Wade Hoffstetter, Paul Serafini, Gerald Mangine
    更新日期:2018-06-16
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  • Activation recovery interval imaging of premature ventricular contraction
    PLOS ONE (IF 2.806) Pub Date : 2018-06-15
    Ting Yang, Long Yu, Qi Jin, Liqun Wu, Bin He
    更新日期:2018-06-16
  • Multi-parametric quantitative MRI reveals three different white matter subtypes
    PLOS ONE (IF 2.806) Pub Date : 2018-06-15
    Jack R. Foucher, Olivier Mainberger, Julien Lamy, Mathieu D. Santin, Alexandre Vignaud, Mathilde M. Roser, Paulo L. de Sousa
    更新日期:2018-06-16
  • Rhenium Complexes of Bis(benzothiazole)‐Based Tetraarylethylenes as Selective Luminescent Probes for Amyloid Fibrils
    Chem. Eur. J. (IF 5.317) Pub Date : 2018-06-15
    Moustafa T. Gabr; F. Christopher Pigge

    Probes for monitoring aggregation of amyloid beta (Aβ) peptides are crucial to advance understanding of the molecular pathogenesis of Alzheimer's Disease (AD). Here, we report luminescent tricarbonyl rhenium complexes of tetraarylethylene (TAE) ligands featuring bis(benzothiazole) chelating groups in combination with (oligo)thiophene units that have been designed for monitoring amyloid fibrillation. Variation in the number of thiophenes influenced the photophysical properties of these complexes, as well as their binding affinities toward Aβ42 fibrils. All complexes displayed submicromolar Kd's for binding Aβ42 aggregates accompanied by up to 34‐fold enhanced luminescence and red‐shifted emission wavelengths. The high binding affinities and desirable photophysical properties of these complexes render them potential alternatives to established fluorescent Aβ probes such as thioflavin T. Additionally, the general and modular design approach implemented in this study should facilitate development of second‐generation TAE‐based diagnostic tools for studying protein aggregation in AD and other neurological diseases.

    更新日期:2018-06-16
  • Design of an intermediate carbon layer between bimetallic sulfide and carbon-based substrate for high-performance asymmetric supercapacitors
    New J. Chem. (IF 3.269) Pub Date : 2018-06-16
    Mengnan Hua, Ting Chen, Houyi Ma

    The design of a flexible electrode based on carbon cloth (CC) which can solve the weak coupled effect and binding force between the substrate and active materials stimulates intensive research on configuring supercapacitors with high energy and power densities. In this paper, a N, P-doped carbon (NPC) layer as an intermediate layer is sandwiched between the active materials and carbon cloth, which can not only make the stable and homogeneous growth of active materials on the carbon fiber but also keep the long life cycling of the flexible electrode in the supercapacitor tests owing to the richly structural defects, excellently hydrophilic characteristic and the mechanism of heteroatom doping. Such a sandwiched flexible electrode consisting of the bimetallic sulfide (BS), N, P-doped carbon layer and carbon cloth (denoted as CC-NPC-BS) is assembled as a positive electrode in the solid-state asymmetric supercapacitor (ASC) device, which delivers a high energy density of 56.7 Wh kg-1 at the power density of 1.5 KW kg-1 and outstanding long cycle stability with 85% capacitance retention after 15000 cycles.

    更新日期:2018-06-16
  • Highly‐Selective Electrochemical Reduction of Dinitrogen to Ammonia at Ambient Temperature and Pressure over Iron Oxide Catalysts
    Chem. Eur. J. (IF 5.317) Pub Date : 2018-06-15
    Xiaoyang Cui; Cheng Tang; Xiaomeng Liu; Chen Wang; Wenjun Ma; Qiang Zhang

    Catalytic conversion of dinitrogen (N2) into ammonia under ambient conditions represents one of the Holy Grails in sustainable chemistry. However, owning to the kinetically complex and energetically challenging N2 reduction reaction (NRR) process, NRR electrocatalysts with high catalytic activity and high selectivity are rare. In this contribution, as a proof‐of‐concept, we demonstrate that both the NH3 yield and NH3 faradaic efficiency (FE) at ambient conditons can be improved by modification of the hematite nanostructure surface. Introducing more oxgygen vancancies to the hematite surface renders improved performance toward NRR, leading to an average NH3 production rate of 0.46 µg·h−1·cm−2 and a corresponding NH3 FE of 6.04% at −0.9 V vs Ag/AgCl in 0.10 M KOH electrolyte. The durability of the electrochemical system was also investigated. A surprisingly high average NH3 production rate of 1.45 µg·h−1·cm−2 and a corresponding NH3 FE of 8.28% was achieved after the first 1 h chrono‐amperometry test. This is among the highest FEs reported so far of non‐precious metal based catalysts using a polymer‐electrolyte‐membrane type cell and much higher than the FEs of precious metal catalysts (e.g. Ru/C) under comparable reaction conditions. However, the NH3 yield and the NH3 FE dropped to 0.29 µg·h−1·cm−2 and 2.74% respectively after 16 h of chrono‐amperometry tests, indicating poor durability of the system.

    更新日期:2018-06-16
  • Phosphorylated Chitosan Armed Hydroxyapatite Nanocomposite for Advancing Activity on Osteoblast and Osteosarcoma cells
    New J. Chem. (IF 3.269) Pub Date : 2018-06-16
    Mariappan Rajan, Sumathra Murugan, Murugan A. Munusamy

    Abstract Recently, applications of traditional medicine in tissue engineering are gaining increasing attention. The components in ginger possess potent antioxidant and anti-inflammatory activities, which are considered to be closely associated with its cancer chemopreventive potential. Here, we report a composite system with a highly efficient, bio-responsive, and potent antioxidant-loaded phosphorylated polymer hydroxyapatite for bone tissue engineering based on the anti-osteosarcoma effect of 6-gingerol. The physicochemical properties of nanocomposites were characterized by fourier transform spectroscopy, X-ray diffraction, scanning electron microscopy, and in vitro drug release, and the antioxidant activity was determined by UV-Vis spectroscopy. Osteoblast (MG63) adhesion and toxicity were tested against the Osteosarcoma cell line (Saos-2). The ALP activities and gene expression after HAP/PCS and HAP/PCS/G nanocomposite treatment were investigated. HAP/PCS/G suppressed osteosarcoma progression. Taken together, HAP/PCS/G could be exploited for advanced graft material development to accelerate bone regeneration as HAP/PCS stimulates osteogenesis and 6-gingerol suppresses osteosarcoma progression. Key words: Gingerol, Hydroxyapatite, Phosphorylated Chitosan, Osteoblast, Osteosarcoma

    更新日期:2018-06-16
  • Redox‐Triggered Folding of Self‐Assembled Coordination Polymers incorporating Viologen Units
    Chem. Eur. J. (IF 5.317) Pub Date : 2018-06-15
    Wathiq Sattar Abdul-Hassan; Denis Roux; Christophe Bucher; saioa cobo; Florian Molton; Eric Saint-Aman; Guy Royal

    We report the study of stimuli‐responsive Zn(II) and Fe(II) coordination polymers (MC34+ or MC24+ with M = Fe2+ or Zn2+). These soluble metallopolymers were formed spontaneously by reaction of an organic ligand (C34+ or C24+) with one molar equivalent of metal ions. The C34+ and C24+ ligands incorporate two chelating terpyridine groups bridged by a redox responsive hinge featuring two viologen units (viologen = N,N'‐dialkyl‐4,4'‐bipyridinium) linked either through propyl (C34+) or ethyl (C24+) chains. The viologen units in the polymer chains were reduced (1e per viologen group) either by bulk electrolysis or by visible‐light irradiation carried out in the presence of a photosensitizer. The 1e reduction of the viologen units in the MC24+ polymers induced a slight decrease in the viscosity of the solutions due to a modification of the overall charge carried by the metallopolymers. In contrast, reduction of coordination polymers involving propyl linkers (MC34+) led to a remarkable increase (~+400%) in observed viscosity. This reversible effect was attributed to a folding of the polymer chains triggered by π‐dimerization of the photo‐generated viologen cation radicals.

    更新日期:2018-06-16
  • Cycloaddition of CO2 to epoxides over a porous covalent triazine-based polymer incorporated with Fe3O4
    New J. Chem. (IF 3.269) Pub Date : 2018-06-16
    Ravi - Seenu, Pillaiyar Puthiaraj, Dong-Wha Park, Wha-Seung Ahn

    Highly porous quaterphenyl-containing covalent triazine polymer (QP-CTP) incorporated with iron oxide nanoparticles (Fe3O4@QP-CTP) was synthesized and applied as a catalyst for cycloaddition of CO2 to epoxides under mild conditions. The synthesized materials were characterized using X-ray powder diffraction, N2 adsorption-desorption isotherm, X-ray photoelectron spectroscopy, transmission electron microscope, and elemental analysis. The Fe3O4@QP-CTP composite in the presence of tetrabutylammonium bromide showed 95% conversion of epoxides with high selectivity to cyclic carbonates at 50 oC, 0.1 MPa CO2 in 12 h. The reaction kinetics was further improved when increasing the temperature to 80 oC. The catalyst was easily recovered using a magnet, and the stability was confirmed by a recycle test, which showed that the catalyst could be re-used minimum of eight consecutive runs without a noticeable decline in catalytic activity. A plausible mechanistic pathway of the cycloaddition reaction over Fe3O4@QP-CTP was also proposed.

    更新日期:2018-06-16
  • The Fabrication of rGO/(PLL/PASP)3@DOX Nanorods with pH‐Switch for Photothermal Therapy and Chemotherapy
    Chem. Eur. J. (IF 5.317) Pub Date : 2018-06-15
    Xiangming Li; Yihe Zhang; Zequn Ma; Meng Fu; Qi An

    The development of well‐controlled drug carriers that are stable and highly effective for the delivery of anticancer agents is challenging. Herein, we report a novel pH‐controlled drug delivery system, utilizing reducing graphene oxide (rGO) ‐polymer self‐assembly films as carriers, for the preparation of effective drug nanocomplex. In this system, rGO‐polymer carriers were constructed by the alternating assembly of poly‐L‐lysine (PLL) and polyaspartic acid (PASP) around the rGO sheets. Furthermore, the rGO‐polymer cores could assemble with negatively charged doxorubicin (DOX) via electrostatic interactions. The DOX embedding efficiency and the morphology of the nanocomplex could be controlled by the number, concentration of rGO‐polymer bilayers and the initial DOX concentration. Importantly, the release of DOX could be regulated by controlling the pH and using a NIR laser. Under acidic conditions, the interactions between the PASP layer and DOX molecules can be broken, resulting in the gradual release of the DOX molecules. Upon NIR irradiation, the release of DOX could be further accelerated and a photothermal effect from rGO induced. Cellular uptake and cytotoxicity experiments indicated that the drug nanocomplex possessed effective anti‐cancer activity. Thus, we present a useful strategy to prepare pH‐responsive drug nanocomplex for combined photothermal and chemical therapy. The nanocomplex can be used as a potential drug delivery system for practical cancer treatment.

    更新日期:2018-06-16
  • NH4B11O16(OH)2: A New Ammonium Borate with Wavy-Shaped Polycyclic 2∞[B11O16(OH)2] Layers
    New J. Chem. (IF 3.269) Pub Date : 2018-06-15
    Chunmei Huang, Fangfang Zhang, Bingbing Zhang, ShiLie Pan, Zhihua Yang

    The ammonium borate NH4B11O16(OH)2 has been successfully synthesized by mild hydrothermal method. Its structure features a new fundamental building block (FBB) [B11O18(OH)2] which is composed by a [B5O10] double-ring and two [B3O5(OH)] single-rings via sharing corner oxygen atoms. The FBBs further condense into 2D wavy-shaped polycyclic layers 2∞[B11O16(OH)2] and form the final framework through hydrogen bonds. Specifically, the effect of the hydroxyl to boron ratio (NOH/NB) on the FBB assembling has been identified in the ammonium borate system. In addition, optical and thermal properties of this compound have been experimentally studied. First-principles calculations have also been carried out in order to understand the electronic structure.

    更新日期:2018-06-16
  • Diphenylamino-substituted Tristyryl vs. Triphenyl Isocyanurates: Improved Conjugation has Minimal Impact on Two-Photon Absorption
    New J. Chem. (IF 3.269) Pub Date : 2018-06-15
    Amedee Triadon, Alphonsine Ngo Ndimba, Nicolas Richy, Anissa Amar, Abdou Boucekkine, Thierry Roisnel, Marie Cifuentes, Mark G Humphrey, Mireille Blanchard-Desce, Olivier Mongin, Frederic Paul

    This contribution reports the synthesis of C87H60N6O3 (3-NPh2), the tristyryl analogue of the triphenylisocyanurate C81H54N6O3 (2-NPh2) which was previously demonstrated to be an active two-photon absorber. Contrary to expectation, planarization and extension of the central pi-system does not lead to a marked improvement of the two-photon absorption cross-section.

    更新日期:2018-06-16
  • Effects of the Substituents of Boron Atoms on Conjugated Polymers Containing B←N Units
    Chem. Eur. J. (IF 5.317) Pub Date : 2018-06-15
    Jun Liu; Tao Wang; Chuandong Dou; Lixiang Wang

    Organoboron chemistry is a new tool to tune the electronic structures and properties of conjugated polymers, which are important for applications in organic opto‐electronic devices. To investigate the effects of substituents of boron atoms on conjugated polymers, we synthesized three conjugated polymers based on double B←N bridged bipyridine (BNBP) with various substituents on the boron atoms. By changing the substituents from four phenyl groups and two phenyl groups/two fluorine atoms to four fluorine atoms, the BNBP‐based polymers show the blue‐shifted absorption spectra, decreased LUMO/HOMO energy levels and enhanced electron affinities, as well as the increased electron mobilities. Moreover, these BNBP‐based polymers can be used as electron acceptors for all‐polymer solar cells. These results demonstrate that the substituents of boron atoms can effectively modulate the electronic properties and applications of conjugated polymers.

    更新日期:2018-06-16
  • Ionic liquids mediated solvothermal synthesis of the 4, 4′-methylenediphenyl diisocyanate (MDI) – an efficient and environment friendly process
    New J. Chem. (IF 3.269) Pub Date : 2018-06-15
    Congwen Duan, Jun You, Bo Liu, Jinlong Ma, Haiping Zhou, Hongbin Zhang, Ji Zhang

    4,4′-Methylenediphenyl diisocyanate (4,4′-MDI) is an immensely important intermediate and employed in the manufacturing of polyurethanes. There are many synthetic routes developed over the decades for the synthesis of 4,4′-MDI which are highly toxic and hazardous in nature for the mass production. In this study, an environmental friendly route is proposed for the synthesis of 4,4′-MDI using 4,4′-Diaminodiphenylmethane and dimethyl carbonate (DMC) as starting materials which are nontoxic in nature. The synthesis of ionic liquids (ILs) and its utilization in the decomposition reaction are being systematically investigated. Imidazole functionalized ionic liquids are prepared for the synthesis of 4,4′-MDI, and their thermal performance was evaluated by TGA. We have found that in comparison with other imidazole functionalized ionic liquids, the 1-ethoxycarbonylmethyl-3-methylimidazolium tetrafluoroborate ([EAmim]BF4) exhibited preferable thermal activity in the decomposition of 4,4′-methylenediphenyl dimethylcarbamate (4,4′-MDC). Moreover, this ILs can be more effective when combined with zinc as a catalyst, which enhances the decomposition of MDC. Under the optimal conditions, the yield of MDI over Zn(OAc)2-[EAmim]BF4 catalyst is gone up to 96%. The mechanism of action of the enhanced performance of the ionic liquids by the catalytic activity of zinc acetate was also investigated.

    更新日期:2018-06-16
  • Fabrication of Fe3O4@Polydopamine@Polyamidoamine Core–Shell Nanocomposites and Its Application for Cu(II) Adsorption
    New J. Chem. (IF 3.269) Pub Date : 2018-06-15
    Yukun Sun, Dongyun Li, Hui Yang, Xingzhong Guo

    The Fe3O4@polydopamine@polyamidoamine (Fe3O4@PDA@PAMAM) core-shell nanocomposites were successfully fabricated through monodispersed Fe3O4 nanoflowers synthesis, PDA modification and PAMAM grafting. The as-prepared single Fe3O4@PDA@PAMAM nanocomposite owns a three-decker core-shell structure with 40~60 nm monodispersed magnetic Fe3O4 nanoflower, which show a perfect balance of magnetic properties and morphology, as core and PDA and PAMAM layers with 10~15 nm thickness as shell, and possesses high relevant saturation magnetization (Ms) (30.25 emu/g), while the coercivity (Hc) (10.85 Oe) and retentivity (Mr) (0.9062 emu/g) were extremely low. The obtained Fe3O4@PDA@PAMAM has a adsorption capacity as high as 97.18 mg/g for Cu(II), and the adsorption process is in conformity with pseudo-second-order kinetics and Langmuir isotherm model. And Moreover, the effect of pH and thermodynamics of adsorption process is also discussed briefly.

    更新日期:2018-06-16
  • Single Synaptic Observation of Cholinergic Neurotransmission on Living Neurons: Concentration and Dynamics
    J. Am. Chem. Soc. (IF 13.858) Pub Date : 2018-06-15
    Mei Shen, Zizheng Qu, Justin DesLaurier, Theresa M. Welle, Jonathan V. Sweedler, Ran Chen
    更新日期:2018-06-16
  • Omnidispersible Hedgehog Particles with Multilayer Coatings for Multiplexed Biosensing
    J. Am. Chem. Soc. (IF 13.858) Pub Date : 2018-06-15
    Douglas G. Montjoy, Joong Hwan Bahng, Aydin Eskafi, Harrison Hou, Nicholas A. Kotov
    更新日期:2018-06-16
  • Self-Assembled Pd(II) Barrels as Containers for Transient Merocyanine Form and Reverse Thermochromism of Spiropyran
    J. Am. Chem. Soc. (IF 13.858) Pub Date : 2018-06-15
    Prodip Howlader, Bijnaneswar Mondal, Prioti Choudhury Purba, Ennio Zangrando, Partha Sarathi Mukherjee
    更新日期:2018-06-16
  • Observation of Magnetodielectric Effect in a Dysprosium-Based Single-Molecule Magnet
    J. Am. Chem. Soc. (IF 13.858) Pub Date : 2018-06-15
    Yu-Xia Wang, Yinina Ma, Yisheng Chai, Wei Shi, Young Sun, Peng Cheng
    更新日期:2018-06-16
  • Fabricating high thermal conductivity rGO/polyimide nanocomposite films via a freeze-drying approach
    RSC Adv. (IF 3.108) Pub Date : 2018-06-15
    Shiyang Wei, Qiaoxi Yu, Zhenguo Fan, Siwei Liu, Zhenguo Chi, Xudong Chen, Yi Zhang, Jiarui Xu
    更新日期:2018-06-16
  • Aqueous supercapacitors based on carbonized silk electrodes
    RSC Adv. (IF 3.108) Pub Date : 2018-06-15
    Limei Zhang, Zhaohui Meng, Qiaoyun Qi, Wen Yan, Naibo Lin, Xiang Yang Liu
    更新日期:2018-06-16
  • Biochar supported sulfide-modified nanoscale zero-valent iron for the reduction of nitrobenzene
    RSC Adv. (IF 3.108) Pub Date : 2018-06-15
    Dejin Zhang, Yang Li, Siqi Tong, Xinbai Jiang, Lianjun Wang, Xiuyun Sun, Jiansheng Li, Xiaodong Liu, Jinyou Shen
    更新日期:2018-06-16
  • Quality-by-Design approach to the fluid-bed coating of ginkgo lactone nanosuspensions
    RSC Adv. (IF 3.108) Pub Date : 2018-06-15
    Jiawei Han, Xin Wang, Jingxian Wang, Lingchong Wang, Lihua Chen, Junsong Li, Wen Li
    更新日期:2018-06-16
  • Utility of the chromogenic and fluorogenic properties of benzofurazan for the assay of milnacipran in human urine and plasma
    RSC Adv. (IF 3.108) Pub Date : 2018-06-15
    Islam M. Mostafa, Mahmoud A. Omar, Dalia M. Nagy, Sayed M. Derayea
    更新日期:2018-06-16
  • Synthesis of Single-walled Carbon Nanotubes Coated with Thiol-reactive Gel via Emulsion Polymerization
    J. Am. Chem. Soc. (IF 13.858) Pub Date : 2018-06-15
    Yukiko Nagai, Yusuke Tsutsumi, Naotoshi Nakashima, Tsuyohiko Fujigaya

    Single-walled carbon nanotubes (SWNTs) have unique near-infrared absorption and photoemission properties that are attractive for in vivo biological applications such as photothermal cancer treatment and bioimaging. Therefore, a smart functionalization strategy for SWNTs to create biocompatible surfaces and introduce various ligands to target active cancer cells without losing the unique optical properties of the SWNTs is strongly desired. This paper reports the de-sign and synthesis of a SWNT/gel hybrid containing maleimide groups, which react with various thiol compounds through Michael addition reactions. In this hybrid, the method called carbon nanotube micelle polymerization was used to non-covalently modify the surface of SWNTs with a cross-linked polymer gel layer. This method can form an extremely stable gel layer on SWNTs; such stability is essential for in vivo biological applications. The monomer used to form the gel layer contained a maleimide group, which was protected with furan in endo-form. The resulting hybrid was treated in water to induce deprotection via retro Diels–Alder reaction and then functionalized with thiol com-pounds through Michael addition. The functionalization of the hybrid was explored using a thiol-containing fluores-cent dye as a model thiol and the formation of the SWNT–dye conjugate was confirmed by energy transfer from the dye to SWNTs. Our strategy offers a promising SWNT-based platform for biological functionalization for cancer targeting, imaging, and treatment.

    更新日期:2018-06-16
  • Modular ipso/ortho Difunctionalization of Aryl Bromides via Palladium/Norbornene Cooperative Catalysis
    J. Am. Chem. Soc. (IF 13.858) Pub Date : 2018-06-15
    Zhe Dong, Gang Lu, Jianchun Wang, Peng Liu, Guangbin Dong

    Palladium/norbornene (Pd/NBE) cooperative catalysis has emerged as a useful tool for preparing poly-substituted arenes; however, its substrate scope has been largely restricted to aryl iodides. While aryl bromides are considered as standard substrates for Pd-catalyzed cross coupling reactions, their use in Pd/NBE catalysis remains elusive. Here we describe the development of general approaches for aryl bromide-mediated Pd/NBE cooperative catalysis. Through careful tuning the phosphine ligands and quenching nucleophiles, ortho amination, acylation and alkylation of aryl bromides have been realized in good efficiency. Importantly, various heteroarene substrates also work well and a wide range of functional groups are tolerated. In addition, the utility of these methods has been demonstrated in sequential cross coupling/ortho functionalization reactions, consecutive Pd/NBE-catalyzed difunctionalization to construct penta-substituted aromatics and two-step meta-functionalization reactions. Moreover, the origin of the ligand effect in ortho amination reactions has been explored through DFT studies. It is expected that this effort would significantly expand the reaction scope and enhance the synthetic potential for Pd/NBE catalysis in preparing complex aromatic compounds.

    更新日期:2018-06-16
  • Topochemical Deintercalation of Al from MoAlB: Stepwise Etching Pathway, Layered Intergrowth Structures, and Two-Dimensional MBene
    J. Am. Chem. Soc. (IF 13.858) Pub Date : 2018-06-15
    Lucas T. Alameda, Parivash Moradifar, Zachary Metzger, Nasim Alem, Raymond E. Schaak

    The synthesis of refractory materials usually relies on high-temperature conditions to drive diffusion-limited solid-state reac-tions. These reactions result in thermodynamically-stable products that are rarely amenable to low-temperature topochemical transformations that post-synthetically modify subtle structural features. Here, we show that topochemical deintercalation of Al from MoAlB single crystals, achieved by room-temperature reaction with NaOH, occurs in a stepwise manner to produce several metastable Mo-Al-B intergrowth phases and a two-dimensional MoB (MBene) monolayer, which is a boride analog to graphene-like MXene carbides and nitrides. A high-resolution microscopic investigation reveals that stacking faults form in MoAlB as Al is deintercalated and that the stacking faulty density increases as more Al is removed. Within nanoscale regions containing high densities of stacking faults, four previously unreported Mo-Al-B (MAB) intergrowth phases were identified, including Mo2AlB2, Mo3Al2B3, Mo4Al3B4, and Mo6Al5B6. One of these deintercalation products, Mo2AlB2, is identified as the likely MAB-phase precursor that is needed to achieve a high-yield synthesis of 2-D MoB, a highly targeted two-dimensional MBene. Microscopic evidence of an isolated MoB monolayer is shown, demonstrating the feasibility of using room-temperature metastable phase engineering and deintercalation to access two-dimensional MBenes.

    更新日期:2018-06-16
  • Asymmetric synthesis of the fully functionalized six-membered ring of trigoxyphin A
    Chem. Commun. (IF 6.319) Pub Date : 2018-06-16
    Jing Feng, Tianzi Yu, Zhijiang Zhang, Jinpeng Li, Shaomin Fu, Juan Chen, Bo Liu

    Asymmetric synthesis of the fully functionalized six-membered ring of trigoxyphin A, a daphnane-type diterpenoid, has been accomplished concisely from D-tartrate derivative. Key elements of this synthesis involve the tandem ozonization/intramolecular HWE reaction to construct the α,β-unsaturated cyclohexenone skeleton, the radical cyclization to introduce the C8 chirality and sequential Kumada cross-coupling/hydroboration-oxidation to introduce the C11 chirality. The target substructure could be synthetically achieved in a multi-gram scale.

    更新日期:2018-06-16
  • Central metal dependent modulation of induced-fit gas uptake in molecular porphyrin solids
    Chem. Commun. (IF 6.319) Pub Date : 2018-06-16
    Hirotomo Nishihara, Mao Ohwada, Takuya Kamimura, Masato Nishimura, Hideki Tanaka, Shotaro Hiraide, Minoru Miyahara, Katsuhiko Ariga, Qingmin Ji, Jun Maruyama, Fumito Tani

    Induced-fit accommodation of a variety of gaseous molecules including non-polar molecules has been demonstrated in porphyrin-based supramolecular architectures for the first time. Moreover, the gas uptake behaviour can be modulated by the central cation of porphyrin.

    更新日期:2018-06-16
Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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