bluuebunny/crossref_metadata_2025_split huggingface dataset:
High Performance Anion Exchange Membrane Fuel Cells Enabled by Fluoropoly(olefin) Membranes
Authors: Zhu Liang , Peng Xiong , Shang Shun‐Li , Kwasny Michael T. , Zimudzi Tawanda J. , Yu Xuedi , Saikia Nayan , Pan Jing , Liu Zi‐Kui , Tew Gregory N. , Mustain William E. , Yandrasits Michael , Hickner Michael A. 
Published: May 2019

AbstractAlthough the peak power density of anion exchange membrane fuel cells (AEMFCs) has been raised from ≈0.1 to ≈1.4 W cm−2 over the last decade, a majority of AEMFCs reported in the literature have not been demonstrated to achieve consistently high performance and steady‐state operation. Poly(olefin)‐based AEMs with fluorine substitution on the aromatic comonomer show considerably higher dimensional stability compared to samples that do not contain fluorine. More importantly, fluorinated poly(olefin)‐based AEMs exhibit high hydroxide conductivity without excessive hydration due to a new proposed mechanism where the fluorinated dipolar monomer facilitates increased hydroxide dissociation and transport. Using this new generation of AEMs, a stable, high‐performance AEMFC is operated for 120 h. When the fuel cell configuration is subjected to a constant current density of 600 mA cm−2 under H2/O2 flow, the cell voltage declines only 11% (from 0.75 to 0.67 V) for the first 20 h during break‐in and the cell voltage loss is low (0.2 mV h−1) over the subsequent 100 h of cell testing. The ease of synthesis, potential for low‐cost commercialization, and remarkable ex situ properties and in situ performance of fluoropoly(olefin)‐based AEM renders this material a benchmark membrane for practical AEMFC applications.
Unraveling the Origin and Mechanism of Nanofilament Formation in Polycrystalline SrTiO3 Resistive Switching Memories
Authors: Kwon Deok‐Hwang , Lee Shinbuhm , Kang Chan Soon , Choi Yong Seok , Kang Sung Jin , Cho Hae Lim , Sohn Woonbae , Jo Janghyun , Lee Seung‐Yong , Oh Kyu Hwan , Noh Tae Won , De Souza Roger A. , Martin Manfred , Kim Miyoung 
Published: May 2019

AbstractThree central themes in the study of the phenomenon of resistive switching are the nature of the conducting phase, why it forms, and how it forms. In this study, the answers to all three questions are provided by performing switching experiments in situ in a transmission electron microscope on thin films of the model system polycrystalline SrTiO3. On the basis of high‐resolution transmission electron microscopy, electron‐energy‐loss spectroscopy and in situ current–voltage measurements, the conducting phase is identified to be SrTi11O20. This phase is only observed at specific grain boundaries, and a Ruddlesden–Popper phase, Sr3Ti2O7, is typically observed adjacent to the conducting phase. These results allow not only the proposal that filament formation in this system has a thermodynamic origin—it is driven by electrochemical polarization and the local oxygen activity in the film decreasing below a critical value—but also the deduction of a phase diagram for strongly reduced SrTiO3. Furthermore, why many conducting filaments are nucleated at one electrode but only one filament wins the race to the opposite electrode is also explained. The work thus provides detailed insights into the origin and mechanisms of filament generation and rupture.
Rising Up: Hierarchical Metal–Organic Frameworks in Experiments and Simulations
Authors: Luo Yi , Ahmad Momin , Schug Alexander , Tsotsalas Manuel 
Published: May 2019

AbstractControlled synthesis across several length scales, ranging from discrete molecular building blocks to size‐ and morphology‐controlled nanoparticles to 2D sheets and thin films and finally to 3D architectures, is an advanced and highly active research field within both the metal–organic framework (MOF) domain and the overall material science community. Along with synthetic progress, theoretical simulations of MOF structures and properties have shown tremendous progress in both accuracy and system size. Further advancements in the field of hierarchically structured MOF materials will allow the optimization of their performance; however, this optimization requires a deep understanding of the different synthesis and processing techniques and an enhanced implementation of material modeling. Such modeling approaches will allow us to select and synthesize the highest‐performing structures in a targeted rational manner. Here, recent progress in the synthesis of hierarchically structured MOFs and multiscale modeling and associated simulation techniques is presented, along with a brief overview of the challenges and future perspectives associated with a simulation‐based approach toward the development of advanced hierarchically structured MOF materials.
Silver‐Nanowire Mesh‐Structured Transparent Conductive Film with Improved Transparent Conductive Properties and Mechanical Performance
Authors: Hu Shaowei , Gu Jiahui , Zhao Weiwei , Ji Hongjun , Ma Xing , Wei Jun , Li Mingyu 
Published: May 2019

AbstractSilver nanowires (AgNWs) are an optimum material for fabricating flexible transparent conductive films (TCFs), which are the primary materials in flexible optoelectronic devices. In most studies, TCFs are produced by coating AgNW onto a substrate to form a random network. However, according to some reports, a mesh‐structured network may allow superior performance. The effects of a mesh structure are quantitatively studied, a simple calculation method to derive property curves of mesh‐structured networks from those of random networks is presented, and a rule to fabricate mesh‐structured TCFs with improved performance is determined. Different networks are then fabricated using a template method and transferred onto a polyethylene terephthalate substrate to produce flexible TCFs. Through a series of experiments, it is verified that the mesh structure makes a positive contribution to both the transparent conductive properties and the flexibility. The transmittance of the film is 95.2% when the sheet resistance is 36.0 Ω sq−1, and the properties of the film are well maintained after 5000 bending cycles at a bending curvature of 5 mm.
Active Separation Control on Thick Wind Turbine Airfoils by Means of Steady and Unsteady Blowing
Authors: Kankatala Prabhu , Bangga Galih 
Published: May 2019

AbstractInvestigations of active flow control (AFC) using steady and unsteady sinusoidal blowing jet on thick wind turbine airfoils are performed. The focus is on improving the performance of the DU 00‐W2‐401 airfoil through parametric study and to discuss the effectiveness of optimized configuration. The unsteady Reynolds‐Averaged Navier‐Stokes (URANS) and delayed‐detached eddy simulation (DDES) approaches are employed with controlled flow conditions. The turbulent statistics produced from the flow development through DDES approach is used to analyze the flow. Unsteadiness associated with the massively separated flows is investigated and a strategy is charted to perform the parametric study efficiently and profitably. The interdependencies of the blowing jet parameters are investigated. The studies address airfoil performance improvement through the nonzero‐net‐mass‐flux (NZNMF) slot blowing at different positions, angles of blowing, flow rates, forcing frequencies, and amplitudes of the blowing jet. The computed time‐averaged aerodynamic force coefficients, pressure distributions, and time‐resolved flow field contours are utilized to analyze the flow conditions at various configurations. A final optimum parametric configuration is found out, which results in improved aerodynamic performance. The optimum configuration is tested for airfoil sections of a 10 MW generic turbine at actual operating inflow conditions and ascertained that it is effective.
Driving Cells with Light‐Controlled Topographies
Authors: Puliafito Alberto , Ricciardi Serena , Pirani Federica , Čermochová Viktorie , Boarino Luca , De Leo Natascia , Primo Luca , Descrovi Emiliano 
Published: May 2019

AbstractCell–substrate interactions can modulate cellular behaviors in a variety of biological contexts, including development and disease. Light‐responsive materials have been recently proposed to engineer active substrates with programmable topographies directing cell adhesion, migration, and differentiation. However, current approaches are affected by either fabrication complexity, limitations in the extent of mechanical stimuli, lack of full spatio‐temporal control, or ease of use. Here, a platform exploiting light to plastically deform micropatterned polymeric substrates is presented. Topographic changes with remarkable relief depths in the micron range are induced in parallel, by illuminating the sample at once, without using raster scanners. In few tens of seconds, complex topographies are instructed on demand, with arbitrary spatial distributions over a wide range of spatial and temporal scales. Proof‐of‐concept data on breast cancer cells and normal kidney epithelial cells are presented. Both cell types adhere and proliferate on substrates without appreciable cell damage upon light‐induced substrate deformations. User‐provided mechanical stimulation aligns and guides cancer cells along the local deformation direction and constrains epithelial colony growth by biasing cell division orientation. This approach is easy to implement on general‐purpose optical microscopy systems and suitable for use in cell biology in a wide variety of applications.
Biocatalytic Degradation Efficiency of Postconsumer Polyethylene Terephthalate Packaging Determined by Their Polymer Microstructures
Authors: Wei Ren , Breite Daniel , Song Chen , Gräsing Daniel , Ploss Tina , Hille Patrick , Schwerdtfeger Ruth , Matysik Jörg , Schulze Agnes , Zimmermann Wolfgang 
Published: May 2019

AbstractPolyethylene terephthalate (PET) is the most important mass‐produced thermoplastic polyester used as a packaging material. Recently, thermophilic polyester hydrolases such as TfCut2 from Thermobifida fusca have emerged as promising biocatalysts for an eco‐friendly PET recycling process. In this study, postconsumer PET food packaging containers are treated with TfCut2 and show weight losses of more than 50% after 96 h of incubation at 70 °C. Differential scanning calorimetry analysis indicates that the high linear degradation rates observed in the first 72 h of incubation is due to the high hydrolysis susceptibility of the mobile amorphous fraction (MAF) of PET. The physical aging process of PET occurring at 70 °C is shown to gradually convert MAF to polymer microstructures with limited accessibility to enzymatic hydrolysis. Analysis of the chain‐length distribution of degraded PET by nuclear magnetic resonance spectroscopy reveals that MAF is rapidly hydrolyzed via a combinatorial exo‐ and endo‐type degradation mechanism whereas the remaining PET microstructures are slowly degraded only by endo‐type chain scission causing no detectable weight loss. Hence, efficient thermostable biocatalysts are required to overcome the competitive physical aging process for the complete degradation of postconsumer PET materials close to the glass transition temperature of PET.
The monocotyledonous underground: global climatic and phylogenetic patterns of geophyte diversity
Authors: Howard Cody Coyotee , Folk Ryan A. , Beaulieu Jeremy M. , Cellinese Nico 
Published: May 2019

PremiseGeophytes—plants that typically possess a bulb, corm, tuber, and/or rhizome—have long captured the attention of hobbyists and researchers. However, despite the economic and evolutionary importance of these traits, the potential drivers of their morphological diversity remain unknown. Using a comprehensive phylogeny of monocots, we test for correlations between climate and geophyte growth form to better understand why we observe such a diversity of underground traits in geophytes. Understanding the evolutionary factors promoting independent origins of these potentially adaptive organs will lend insights into how plants adapt to environmental hardships.MethodsUsing a comprehensive phylogeny incorporated with global occurrence and climate data for the monocots, we investigated whether climatic patterns could explain differences between geophytes and non‐geophytes, as well as differences among bulbous, cormous, tuberous, rhizomatous, and non‐geophytic taxa. We used phylogenetically‐informedANOVAs,MANOVAs, andPCAs to test differences in climatic variables between the different growth forms.ResultsGeophytes inhabit cooler, drier, and more thermally variable climates compared to non‐geophytes. Although some underground traits (i.e., bulb, corm, and tuber) appear to inhabit particular niches, a result supported by strong phylogenetic signal, our data has limited evidence for an overall role of climate in the evolution of these traits. However, temperature may be a driving force in rhizome evolution, as well as the evolution of taxa which we considered here as non‐geophytic (e.g., trees, epiphytes, etc.).ConclusionsWhile precipitation patterns have played a role in the evolution of geophytism, our results suggest that temperature should be more strongly considered as a contributing factor promoting the evolution of belowground bud placement, specifically in rhizomatous and non‐geophytic taxa. Bulbous, cormous, and tuberous taxa need closer examination of other mechanisms, such as anatomical constraints or genetic controls, in order to begin to understand the causes behind the evolution of their underground morphology.
1,3,5‐Triphenylpyrazoline‐Based Organocatalysis: Synthesis of Aryl‐Heteroaryl Compounds and Exploiting By‐Product from the Reaction for Alkyne‐Carbonyl Metathesis (ACM) Reaction in One Pot
Authors: Annes Sesuraj Babiola , Ramesh Subburethinam 
Published: May 2019

AbstractA pyrazoline‐based organocatalyst was synthesized and used for the sequential formation of two structurally important heterocyclic compounds in one pot. A variety of substrates were found to be suitable for both arylation and alkyne‐carbonyl metathesis (ACM) reactions. Control reactions were performed to understand the catalytic pathway and a suitable mechanism was proposed.
Composition and stability of the vervet monkey milk microbiome
Authors: Petrullo Lauren , Jorgensen Matthew J. , Snyder‐Mackler Noah , Lu Amy 
Published: May 2019

AbstractThe human milk microbiome is vertically transmitted to offspring during the postnatal period and has emerged as a critical driver of infant immune and metabolic development. Despite this importance in humans, the milk microbiome of nonhuman primates remains largely unexplored. This dearth of comparative work precludes our ability to understand how species‐specific differences in the milk microbiome may differentially drive maternal effects and limits how translational models can be used to understand the role of vertically transmitted milk microbes in human development. Here, we present the first culture‐independent data on the milk microbiome of a nonhuman primate. We collected milk and matched fecal microbiome samples at early and late lactation from a cohort of captive lactating vervet monkeys (N = 15). We found that, similar to humans, the vervet monkey milk microbiome comprises a shared community of taxa that are universally present across individuals. However, unlike in humans, this shared community is dominated by the genera Lactobacillus, Bacteroides, and Prevotella. We also found that, in contrast to previous culture‐dependent studies in humans, the vervet milk microbiome exhibits greater alpha‐diversity than the gut microbiome across lactation. Finally, we did not find support for the translocation of microbes from the gut to the mammary gland within females (i.e., “entero‐mammary pathway”). Taken together, our results show that the vervet monkey milk microbiome is taxonomically diverse, distinct from the gut microbiome, and largely stable. These findings demonstrate that the milk microbiome is a unique substrate that may selectively favor the establishment and persistence of particular microbes across lactation and highlights the need for future experimental studies on the origin of microbes in milk.
Spin Transport over Huge Distances in a Magnetized 2D Electron System
Authors: Gorbunov Alexander V. , Kuznetsov Vladimir A. , Zhuravlev Andrey S. , Kulik Leonid V. , Dickmann Sergey , Timofeev Vladislav B. 
Published: May 2019

AbstractExperimental results on the properties of a recently discovered new collective state, the magnetofermionic condensate, are summarized herein. Condensation occurs in a fermionic system, a quantum Hall insulator (filling factor ν = 2), as a result of the formation of a dense ensemble of long‐lived spin cyclotron magnetoexcitons, composite bosons. At temperatures below 1 K, the exciton ensemble exhibits a sharp enhancement in its response to an external electromagnetic field due to the formation of a super‐absorbing state that interacts coherently with the electromagnetic field. Simultaneously, the electrons below the Fermi level rearrange to form a new non‐equilibrium radiative recombination channel. The condensate shows a sharp decrease in viscosity and the ability to spread over macroscopically large distances, on the order of a millimeter, at a speed of . Due to this rapid long‐distance spin transfer, new opportunities in the field of spintronics have been opened up.
A Universal Quantitative Descriptor of the Dispersion Interaction Potential
Authors: Pollice Robert , Chen Peter 
Published: May 2019

AbstractLondon dispersion, universally attractive forces originating from fluctuating dipoles, is omnipresent in molecules. While its understanding has recently made tremendous progress, its general appreciation is still lagging behind electrostatics. This can be explained by the simple tools available to study electrostatic interactions, such as electrostatic potential (ESP) maps and partial charges, and a lack thereof for dispersion. We herein report a universal quantitative descriptor of dispersion interaction potentials, which allows assessing dispersion visually by London dispersion potential (LDP) maps, and quantitatively using the average LDP on the van der Waals surface. We demonstrate the utility of these new tools by constructing a quantitative dispersion energy scale of the elements and common substituents, studying non‐covalent interactions (NCIs), and developing modern linear free energy relationships in catalysis.
Jumping Crystal of a Hydrogen‐Bonded Organic Framework Induced by the Collective Molecular Motion of a Twisted π System
Authors: Takeda Takashi , Ozawa Masataka , Akutagawa Tomoyuki 
Published: May 2019

AbstractThere is a limited number of reports on mechanically responsive molecular crystals, including thermo‐responsive and light‐responsive crystals. Rigid ordered molecular crystals with a close‐packing structure are less able to accept distortion, which hampers the development of such molecular crystals. The thermosalient effect, or “crystal jumping”, refers to a thermo‐responsive system that converts heat into mechanical force by thermally induced phase transition. While they have recently attracted attention as potential highly efficient molecular actuators, less than two dozens of thermosalient molecular crystals have been reported to date, and the design of such molecules as well as how they assemble to express a thermosalient effect are unknown. Herein, we demonstrate how the cooperative molecular motion of twisted π units could serve to develop a thermo‐responsive jumping molecular crystal with a hydrogen‐bonded organic framework (HOF) of tetra[2,3]thienylene tetracarboxylic acid (1). The cooperative change in the molecular structure triggered by the desolvation of THF in the channel of the HOF structure induced not only a change in the structure of HOF but also mechanical force. Hydrogen bonding interactions contributed significant thermal stability to maintain the HOF assembly even with a dynamic structural change.
L‐menthol‐based initiators for atom transfer radical polymerization of styrene
Authors: Vishwakarma Sambhav , Kumari Archana , Mitra Kheyanath , Singh Shikha , Singh Rajshree , Singh Jaydeep , Sen Gupta Susanta K. , Ray Biswajit 
Published: May 2019

ABSTRACTTwo new atom transfer radical polymerization (ATRP) initiators, 2‐isopropyl‐5‐methylcyclohexyl 2‐bromopropanoate (1) and 2‐Isopropyl‐5‐methylcyclohexyl 2‐bromo‐2‐methylpropanoate (2), have been synthesized by the reaction of 2‐bromopropanoyl bromide and 2‐bromo‐2‐methylpropanoyl bromide, respectively, with L‐menthol and characterized by1H and13C NMR and FTIR spectroscopic studies. ATRP of styrene has successfully been carried out in a control manner using these initiators along with catalyst/ligand system consisting of Cu(I)Br/N,N,N/,N/,N//‐pentamethyldiethylenetriamine. Polymerizations have yielded polystyrenes (PSts) of controlled molecular weight with low polydispersity index having a menthyl end group, as confirmed by1H NMR and gel permeation chromatography [GPC]. The controlled nature of the polymerization has also been confirmed by kinetic study of the polymerization process monitored via1H NMR and GPC. Initiator2has evolved as most efficient among the two. The obtained end‐functional PSt has also been used as a macroinitiator for homochain extension with styrene and heterochain extension with methyl methacrylate to produce PSt‐b‐PMMA, showing the living nature of the polymerization process. In comparison with the PSt sample prepared using widely used initiator ethyl‐2‐bromo‐isobutyrate with almost the same molecular weight and polydispersity, initiator2‐made L‐menthyl‐capped PSt has shown higher light transmission properties of its dichloromethane solution at ~259 nm, higher thermal stability, lower glass transition temperature, a broad melting temperature, and higher surface roughness over its film. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2019,136, 47964.
New structure found in a filter cake with the addition of an amphoteric polymer fluid loss additive
Authors: Cui Wuge , Jiang Guancheng , He Yinbo 
Published: May 2019

ABSTRACTWater‐based drilling fluids always suffer from high‐salt and high‐temperature conditions, which cause safety andeconomic problems. Amphoteric copolymers are expected to solve this, although the underlying factors are still controversial. In this study, the AST (an amphoteric copolymer which was synthesized from 2‐acrylamide‐2‐methyl propane sulfonicacid, (3‐acrylamidopropyl)trimethyl ammonium chloride and acrylamide) was used as fluid loss additive, kaolinite (KT) was used as an evaluation condition, and a sandwich structure was found on the cross section of the filter cake. Four potential mainstream explanations were analyzed: the polymer properties, rheological behavior, dispersion of platelets, and structure of the filter cake. The sandwich structures in the cross section of filter cake were finally found and were confirmed by energy‐dispersive spectroscopy. The sandwich structure, which consisted of an amphoteric polymer and a clay platelet, affected the fluid loss dramatically. This method for studying the cross section of the filter cake on the basis of KT evaluation could be used to investigate the filtration process of other fluid loss additives. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47965.