bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transfer‐Free Synthesis of Lateral Graphene–Hexagonal Boron Nitride Heterostructures from Chemically Converted Epitaxial Graphene
Authors: Bradford Jonathan , Shafiei Mahnaz , MacLeod Jennifer , Motta Nunzio 
Published: July 2019

AbstractThe synthesis of lateral heterostructures of graphene and hexagonal boron nitride (h‐BN) has attracted attention due to the ability to broadly tune the electronic properties of the hybrid monolayer. Conventional synthesis methods for lateral heterostructures rely on chemical vapor deposition on metal surfaces, and application of the heterostructure in devices requires transfer of the material onto a suitable substrate during which the sample is susceptible to damage or contamination. Herein, a transfer‐free synthesis method to produce lateral heterostructures of graphene and h‐BN by chemical conversion of epitaxial graphene on 6H‐SiC(0001) is demonstrated. X‐ray photoelectron spectroscopy measurements confirm the substitution of graphene with h‐BN, while scanning tunneling microscopy reveals that the h‐BN domains reside in‐plane with graphene forming an interface along the zig‐zag direction. Raman spectroscopy measurements provide insight into the reaction mechanism in which h‐BN is substituted for graphene at defect sites thereby reducing the defect density in the lateral heterostructure. The development of scalable, transfer‐free synthesis methods for lateral heterostructures of graphene and h‐BN, as demonstrated in this work, is expected to facilitate a route toward large‐scale synthesis of 2D semiconductors and atomically thin circuitry directly on‐chip.
Atomic‐Scale Study of Metal–Oxide Interfaces and Magnetoelastic Coupling in Self‐Assembled Epitaxial Vertically Aligned Magnetic Nanocomposites
Authors: Radtke Guillaume , Hennes Marcel , Bugnet Matthieu , Ramasse Quentin M. , Weng Xiaorong , Demaille Dominique , Gobaut Benoit , Ohresser Philippe , Otero Edwige , Choueikani Fadi , Juhin Amélie , Sainctavit Philippe , Zheng Yunlin , Vidal Franck 
Published: July 2019

AbstractVertically aligned nanocomposites (VANs) of metal/oxide type have recently emerged as a novel class of heterostructures with great scientific and technological potential in the fields of nanomagnetism, multiferroism, and catalysis. One of the salient features of these hybrid materials is their huge vertical metal/oxide interface, which plays a key role in determining the final magnetic and/or transport properties of the composite structure. However, in contrast to their well‐studied planar counterparts, detailed information on the structural features of vertical interfaces encountered in VANs is scarce. In this work, high resolution scanning transmission electron microscopy (STEM) and electron energy‐loss spectroscopy (EELS) are used to provide an element selective atomic‐scale analysis of the interface in a composite consisting of ultrathin, self‐assembled Ni nanowires, vertically epitaxied in a SrTiO3/SrTiO3(001) matrix. Spectroscopic EELS measurements evidence rather sharp interfaces (6–7 Å) with the creation of metallic NiTi bonds and the absence of nickel oxide formation is confirmed by X‐ray absorption spectroscopy measurements. The presence of these well‐defined phase boundaries, combined with a large lattice mismatch between the oxide and metallic species, gives rise to pronounced magnetoelastic effects. Self‐assembled columnar Ni:SrTiO3 composites thus appear as ideal model systems to explore vertical strain engineering in metal/oxide nanostructures.
Gecko‐Effect Inspired Soft Gripper with High and Switchable Adhesion for Rough Surfaces
Authors: Tian Hongmiao , Li Xiangming , Shao Jinyou , Wang Chao , Wang Yan , Tian Yazhou , Liu Haoran 
Published: July 2019

AbstractGeckos, which can walk upside down on smooth or rough surfaces, owe this ability to the hierarchical structures under their toes. These structures are responsible for substantial adhesion and, at the same time, for quick attachment/detachment by mechanical stimulus of toe muscles. Inspired by such stimuli‐responsive systems in nature, an active adhesive soft gripper for rough surfaces is proposed in this study, consisting of the mushroom‐like morphology acting as adhesive structures and the pressure controllable deformation working as toe muscles. Through tunable pressure, the adhesive force can be increased and reduced by roughly 20‐fold for a ground glass, in which it can quickly reach high adhesion with positive pressure and reduce to small adhesion under negative pressure. This gecko inspired soft gripper is tested and found successful as a pick‐up and drop‐down system for transporting a surface with different features, composed of rough acrylic plate, steel ball, flexible photo paper, heavy glass block/plate, etc., which will have great potential for applications in industrial line and daily life as well as providing a novel perspective for the design of soft grippers.
Stability and Dark Hysteresis Correlate in NiO‐Based Perovskite Solar Cells
Authors: Di Girolamo Diego , Matteocci Fabio , Kosasih Felix Utama , Chistiakova Ganna , Zuo Weiwei , Divitini Giorgio , Korte Lars , Ducati Caterina , Di Carlo Aldo , Dini Danilo , Abate Antonio 
Published: July 2019

AbstractIn perovskite solar cells (PSCs), the interfaces are a weak link with respect to degradation. Electrochemical reactivity of the perovskite's halides has been reported for both molecular and polymeric hole selective layers (HSLs), and here it is shown that also NiO brings about this decomposition mechanism. Employing NiO as an HSL in p–i–n PSCs with power conversion efficiency (PCE) of 16.8%, noncapacitive hysteresis is found in the dark, which is attributable to the bias‐induced degradation of perovskite/NiO interface. The possibility of electrochemically decoupling NiO from the perovskite via the introduction of a buffer layer is explored. Employing a hybrid magnesium‐organic interlayer, the noncapacitive hysteresis is entirely suppressed and the device's electrical stability is improved. At the same time, the PCE is improved up to 18% thanks to reduced interfacial charge recombination, which enables more efficient hole collection resulting in higher Voc and FF.
Mechanism by which Tungsten Oxide Promotes the Activity of Supported V2O5/TiO2 Catalysts for NOX Abatement: Structural Effects Revealed by 51V MAS NMR Spectroscopy
Authors: Jaegers Nicholas R. , Lai Jun‐Kun , He Yang , Walter Eric , Dixon David A. , Vasiliu Monica , Chen Ying , Wang Chongmin , Hu Mary Y. , Mueller Karl T. , Wachs Israel E. , Wang Yong , Hu Jian Zhi 
Published: July 2019

AbstractThe selective catalytic reduction (SCR) of NOx with NH3 to N2 with supported V2O5(‐WO3)/TiO2 catalysts is an industrial technology used to mitigate toxic emissions. Long‐standing uncertainties in the molecular structures of surface vanadia are clarified, whereby progressive addition of vanadia to TiO2 forms oligomeric vanadia structures and reveals a proportional relationship of SCR reaction rate to [surface VOx concentration]2, implying a 2‐site mechanism. Unreactive surface tungsta (WO3) also promote the formation of oligomeric vanadia (V2O5) sites, showing that promoter incorporation enhances the SCR reaction by a structural effect generating adjacent surface sites and not from electronic effects as previously proposed. The findings outline a method to assess structural effects of promoter incorporation on catalysts and reveal both the dual‐site requirement for the SCR reaction and the important structural promotional effect that tungsten oxide offers for the SCR reaction by V2O5/TiO2 catalysts.
Sustainable Synthesis of Pure Silica Zeolites from a Combined Strategy of Zeolite Seeding and Alcohol Filling
Authors: Wu Qinming , Zhu Longfeng , Chu Yueying , Liu Xiaolong , Zhang Changsheng , Zhang Juan , Xu Hao , Xu Jun , Deng Feng , Feng Zhaochi , Meng Xiangju , Xiao Feng‐Shou 
Published: July 2019

AbstractCurrently, the synthesis of pure silica zeolites always requires the presence of organic structure‐directing agents (OSDAs), which direct the assembly pathway and ultimately fill the pore space. A sustainable route is now reported for synthesizing pure silica zeolites in the absence of OSDAs from a combined strategy of zeolite seeding and alcohol filling, where the zeolite seeds direct crystallization of zeolite crystals from amorphous silica, while the alcohol is served as pore filling in the zeolites. Very importantly, the alcohol could be fully washed out from zeolite pores by water at room temperature, which completely avoids calcination at high temperature for removal of OSDAs in the synthesis of pure silica zeolites.
Mussel‐Inspired Two‐Dimensional Freestanding Alkyl‐Polydopamine Janus Nanosheets
Authors: Sheng Wenbo , Li Wei , Yu Bo , Li Bin , Jordan Rainer , Jia Xin , Zhou Feng 
Published: July 2019

AbstractMussel‐inspired two‐dimensional freestanding, alkyl‐polydopamine (alkyl‐PDA) Janus nanosheets, with a well‐controlled nanometer thickness and a lateral size of up to micrometers, have been developed. A self‐assembled octadecylamine (ODA) bilayer is used as the reactive template for the dopamine polymerization, resulting in the formation of well‐defined nanosheets. The alkyl‐PDA nanosheets show an amphiphilic nature with hydrophilic PDA and hydrophobic alkyl chains on opposing sides. The nanosheets can be used to functionalize many substrates and is dependent on the configuration of surface of the nanosheets. The nanosheets are quite stable, as the morphology is preserved after carbonization at 900 °C. Post‐modification of the nanosheets can be easily achieved because of the reactive nature of PDA. This work will provide a new strategic approach for fabricating polymeric Janus nanosheets, which can find applications for surface modifications, catalyst supports, and guided self‐assembly.
An Asymmetric Supercapacitor–Diode (CAPode) for Unidirectional Energy Storage
Authors: Zhang En , Fulik Natalia , Hao Guang‐Ping , Zhang Han‐Yue , Kaneko Katsumi , Borchardt Lars , Brunner Eike , Kaskel Stefan 
Published: July 2019

AbstractA new asymmetric capacitor concept is proposed providing high energy storage capacity for only one charging direction. Size‐selective microporous carbons (w<0.9 nm) with narrow pore size distribution are demonstrated to exclusively electrosorb small anions (BF4−) but size‐exclude larger cations (TBA+ or TPA+), while the counter electrode, an ordered mesoporous carbon (w>2 nm), gives access to both ions. This architecture exclusively charges in one direction with high rectification ratios (RR=12), representing a novel capacitive analogue of semiconductor‐based diodes (“CAPode”). By precise pore size control of microporous carbons (0.6 nm, 0.8 nm and 1.0 nm) combined with an ordered mesoporous counter electrode (CMK‐3, 4.8 nm) electrolyte cation sieving and unidirectional charging is demonstrated by analyzing the device charge‐discharge response and monitoring individual electrodes of the device via in situ NMR spectroscopy.
Oxygen‐Triggered Switchable Polymerization for the One‐Pot Synthesis of CO2‐Based Block Copolymers from Monomer Mixtures
Authors: Zhao Yajun , Wang Yong , Zhou Xingping , Xue Zhigang , Wang Xianhong , Xie Xiaolin , Poli Rinaldo 
Published: July 2019

AbstractSwitchable polymerization provides the opportunity to regulate polymer sequence and structure in a one‐pot process from mixtures of monomers. Herein we report the use of O2 as an external stimulus to switch the polymerization mechanism from the radical polymerization of vinyl monomers mediated by (Salen)CoIII−R [Salen=N,N′‐bis(3,5‐di‐tert‐butylsalicylidene)‐1,2‐cyclohexanediamine; R=alkyl] to the ring‐opening copolymerization (ROCOP) of CO2/epoxides. Critical to this process is unprecedented monooxygen insertion into the Co−C bond, as rationalized by DFT calculations, leading to the formation of (Salen)CoIII−O−R as an active species to initiate ROCOP. Diblock poly(vinyl acetate)‐b‐polycarbonate could be obtained by ROCOP of CO2/epoxides with preactivation of (Salen)Co end‐capped poly(vinyl acetate). Furthermore, a poly(vinyl acetate)‐b‐poly(methyl acrylate)‐b‐polycarbonate triblock copolymer was successfully synthesized by a (Salen)cobalt‐mediated sequential polymerization with an O2‐triggered switch in a one‐pot process.
Different Modes of Anion Response Cause Circulatory Phase Transfer of a Coordination Cage with Controlled Directionality
Authors: Mihara Nozomi , Ronson Tanya K. , Nitschke Jonathan R. 
Published: July 2019

AbstractControlled directional transport of molecules is essential to complex natural systems, from cellular transport up to organismal circulatory systems. In contrast to these natural systems, synthetic systems that enable transport of molecules between several spatial locations on the macroscopic scale, when external stimuli are applied, remain to be explored. Now, the transfer of a supramolecular cage is reported with controlled directionality between three phases, based on a cage that responds reversibly in two distinct ways to different anions. Notably, circulatory phase transfer of the cage was demonstrated based on a system where the three layers of solvent are arranged within a circular track. The direction of circulation between solvent phases depended upon the order of addition of anions.
Nickel‐Catalyzed Regioselective Hydroalkylation and Hydroarylation of Alkenyl Boronic Esters
Authors: Bera Srikrishna , Hu Xile 
Published: July 2019

AbstractMetal hydride catalyzed hydrocarbonation reactions of alkenes are an efficient approach to construct new carbon–carbon bonds from readily available alkenes. However, the regioselectivity of hydrocarbonation remains challenging to be controlled. In nickel hydride (NiH) catalyzed hydrocarbonation, linear selectivity is most often obtained because of the relative stability of the linear Ni–alkyl intermediate over its branched counterpart. Herein, we show that the boronic pinacol ester (Bpin) group directs a Ni‐catalyzed hydrocarbonation to occur at its adjacent carbon center, resulting in formal branch selectivity. Both alkyl and aryl halides can be used as electrophiles in this hydrocarbonation, providing access to a wide range of secondary alkyl Bpin derivatives, which are valuable building blocks in synthetic chemistry. The utility of the method is demonstrated by the late‐stage functionalization of natural products and drug molecules, the synthesis of an anticancer agent, and iterative syntheses.
Role of π‐π interactions and chain flexibility in dispersion and dynamic‐mechanical properties of nanocomposites with multiple wall carbon nanotubes
Authors: Hamester Michele Regina Rosa , Dalmolin Carla , Becker Daniela 
Published: July 2019

ABSTRACTTwo polymers of same functional group were used; one with greater chain flexibility, PA 6.6, and the other with two benzene rings in the main chain, PA 6I‐6T (aPA), to evaluate how the structure influences on the nanoparticle dispersion homogeneity and on dynamic‐mechanical properties. In the aPA nanocomposites, good dispersion and homogeneous distribution were observed for all CNT concentrations. However, PA 6.6 nanocomposites showed agglomerated regions in all formulations. The interfacial energy of the aPA/CNT was five times lower than that of PA6.6/CNT, resulting in greater compatibility in this nanocomposite. An increase of up to 26% was observed with 2.5% of CNT in aPA nanocomposites storage modulus. In the samples with PA 6.6, the increase was at most 5%. Even with greater flexibility of PA 6.6 macromolecules, the π‐π interaction between the aPA aromatic rings and CNTs might be the decisive factor for dispersion improvement and positively influence on the dynamic‐mechanical properties of these nanocomposites. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48195.
Preparation, structure, and pervaporation performance of poly(amide–imide)‐sulfonated polyimide composites
Authors: Kononova S. V. , Sapegin D. A. , Kruchinina E. V. , Gubanova G. N. , Romashkova K. A. , Didenko A. L. , Smirnova V. E. , Popova E. N. , Saprykina N. N. , Vlasova E. N. , Svetlichnyi V. M. 
Published: July 2019

ABSTRACTPoly{[4,4′‐bisdiphenyl‐2,2′‐disulfonic acid]imide‐1,3‐bis(3,4‐dicarboxyphenoxy)benzene} was synthesized via polycondensation and subsequent thermal imidization in m‐cresol:triethylamine. The obtained polymer and its composites with aromatic poly(amide–imide) obtained through polycondensation of 4‐chloroformyl‐(N‐p‐chloroformylphenyl)phthalimide and 4,4′‐diaminodiphenyl ether were investigated by use of nuclear magnetic resonance, thermogravimetric analysis, dynamic mechanical analysis, differential scanning calorimetry, Fourier transform infrared spectroscopy, scanning electron microscopy, and X‐ray diffraction analysis. Transport properties of composite films were studied during pervaporation of water–alcohol mixtures. On the basis of the data obtained, suggestions on the structure of materials and its influence on transport and other physical properties were made. The addition of 30 wt % of sulfonated polyimide to the poly(amide–imide) matrix enhances its separation factor in the process of separation of an azeotrope water/ethanol mixture by four times while permeability remains unchanged. The methanol permeability increases with an increase of the mass fraction of sulfonated polyimide in the composite film. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48197.
Hydrophobic SiO2 nanoparticle‐induced polyvinylidene fluoride crystal phase inversion to enhance permeability of thin film composite membrane
Authors: Sun Hao , Liu Yijun , Li Dan , Liu Bing , Yao Jie 
Published: July 2019

ABSTRACTThin film composite (TFC) membrane can get rid of small molecular contaminants and salts with a very high efficiency, thus exhibiting promising potential for addressing the emerging problem of a clean water shortage. In this work, a new type of TFC membrane was prepared by interfacial polymerization of two monomers (MPD and TMC) on surface of SiO2/polyvinylidene fluoride (PVDF) substrate. The maximum flux of 3.16 L m−2 h−1 Bar−1 was achieved for the optimized hydrophobic SiO2 nanoparticles well dispersed in PVDF substrate, which is 2.6 times higher than that of 1.21 L m−2 h−1 Bar−1 for the commercial cellulose triacetate reverse osmosis membrane. The improved performance of TFC membrane could be attributed to the higher compaction resistance of SiO2/PVDF substrate. Further analysis revealed that PVDF crystal phase inversion induced by superhydrophobic SiO2 nanoparticles obviously enhanced the intramolecular and intermolecular hydrogen bonds between PVDF polymer molecules. Additionally, the narrower finger‐like pore size and thicker pore wall of SiO2/PVDF substrate also played significant roles in enhancing the compaction resistance of PVDF membrane. This work also provides a proof‐of‐concept demonstration of high permeability substrates for effective flux enhancement of TFC membranes. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48204.
Free volume correlation with electrical conductivity of polycarbonate/reduced graphene oxide nanocomposites studied by positron annihilation lifetime spectroscopy
Authors: Zhong Jiang , Ding Yang , Gao Fei , Wen Jia , Zhou Jiyong , Zheng Wenbin , Shen Liang , Fu Changqing , Wang Bo 
Published: July 2019

ABSTRACTThe reduced graphene oxide (RGO) was added to polycarbonate (PC) through solvent mixing. The influences of RGO on the free volumes and electrical conductivity of PC were systemically studied by positron annihilation lifetime spectroscopy (PALS), Fourier‐transform infrared spectroscopy, transmission electron microscope, and electrical conductivity measurements for PC/RGO nanocomposites. The nanosized effect, good conductivity of RGO, and strong interfacial interaction between RGO and PC result in the low conductive threshold of 0.36 wt %. Ten orders of magnitude increase in electrical conductivity was obtained. The results of PALS indicate the properties of free volumes fluctuate around the conductive percolation threshold. The conformational change of PC segments in the interfacial region induced by the strong interfacial interaction leads to an increase in free volume radius. The concentration of free volume decreases due to the depression of free volume holes as the introduction of RGO. Significantly, an exponential function is proposed to describe the effect of relative fractional free volume on the electrical conductivity, suggesting that free volume plays an important role in regulating electrical conductivity of PC/RGO. The physical quantity fd that refers required fractional free volume of polymer composites from insulating to conducting phase is found. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48207.
Convection, latent heating and potential temperature budget in the rapidly intensifying Typhoon Mujigae (2015)
Authors: Tang Xiba , Yang Shuai , Ping Fan , Li Mengxia , Peng Jing 
Published: July 2019

AbstractBased on a 72‐hr simulation of the rapidly intensifying Typhoon Mujigae (2015), the spatiotemporal evolutions of various inner‐core convections and the associated latent heating (LH) features were investigated. Results showed two interesting turning points from the pre‐rapid intensification (RI) stage to RI onset. One was a change from convective–stratiform mixed precipitation to a convective precipitation (CP)‐dominant trend, while the other happened inside the CP. As the major contributor to LH, during the CP, the dramatic increase and radially inward movement of deep convection and associated LH release from −4 to −2 hr relative to RI, provided some useful clues for predicting the RI of a tropical cyclone (TC). But how do distinct convections act on the RI of a TC? From the potential temperature budget and flow vector intuitive display, there were upper‐ and lower‐level warm cores, fed by the centripetal transport from deep‐convection‐related LH sources and lower‐level radial inflow of weak‐to‐moderate convection‐associated LH sources. The former brought about higher heating efficiency, embodied by a higher rate (2.5 times greater) of pressure decline during RI. Thus, by comparing the LH effects of diverse convections on warm‐core formation, and the role of the warm core in the RI of a TC, the link between various convections and TC intensification can be established.
Re‐assessing effects of bromide and granular activated carbon on disinfection byproduct formation
Authors: Wang Lili , Vacs Renwick Deborah , Regli Stig 
Published: July 2019

AbstractWhile granular activated carbon (GAC) can effectively remove disinfection byproduct (DBP) precursors, its use has raised concerns over the increased formation of some brominated DBP (Br‐DBP) species in treated water postchlorination, especially for waters with high bromide concentrations. The Information Collection Rule Treatment Study Database contains the results of the most extensive GAC studies ever conducted nationwide. Data were analyzed to assess the extent of DBP speciation changes and the overall reduction of Br‐DBPs by GAC to gain new insights into the bromide effect. Results showed that formation of three brominated trihalomethanes (collectively Br‐THM3) varied greatly depending on total organic carbon (TOC) removal and bromide concentrations. Low TOC concentrations in GAC effluents resulted in greatly reduced Br‐THM3 formation, except for a few cases where Br‐THM3 formation increased. GAC followed by chloramination were likely to better control Br‐THM3 formation for waters with high TOC and high bromide. Finally, chlorine demand reduction by GAC was quantified.