pinecone/core-2020-05-10-deduplication huggingface dataset:
Generating heat from conducting polypyrrole-coated PET fabrics

Heating effects in polypyrrole-coated polyethyleneterephthalate (PET)-Lycra&reg; fabrics were studied. Chemical synthesis was employed to coat the PET fabrics by polypyrrole using ferric chloride as oxidant and antraquinone- 2-sulfonic acid (AQSA) and naphthalene sulfonic acid (NSA) as dopants. The coated fabrics exhibited reasonable electrical stability, possessed high electrical conductivity, and were effective in heat generation. Surface resistance of polypyrrole-coated fabrics ranged from approximately 150 to 500 /square. Different connections between conductive fabrics and the power source were examined. When subjected to a constant voltage of 24 V, the current transmitted through the fabric decreased about 10% in 72 h. An increase in resistance of conductive fabrics subjected to constant voltage was observed<br /
Preparation and property evaluation of nanocomposites based on polyurethane-modified epoxy/montmorillonite systems

Montmorillonite nanoclay and polyurethanes obtained from polyethylene glycol (PUR 400) and polyoxypropylene diol (PUR 1002) were used to enhance the mechanical properties of an epoxy resin. Maximum impact strength impovement was obtained with composition containing 2% nanoclay and 10%% PUR 400 as well as that with 1% nanoclay and 15% PUR 400, corresponding to 110% and 75%, respectively, in relation to the unmodified epoxy resin. Moreover, a 10-fold increase was observed with respect to the flexural strain at break for the composition containing 15% PUR 1002 and 2% nanoclay. SEM micrographs have indicated that the mechanism of mechanical property enhancement is associated with increased yield of the epoxy matrix. Moreover, FTIR results showed that some chemical reactions have taken place between the hydroxyl groups of epoxy resin and the isocyanate groups of polyurethane, explaining partly the improvement in the mechanical properties of the polymer matrix
Processing thermoplastic matrix towpregs by pultrusion

In the work reported herein, glass fiber reinforced polypropylene towpregs, produced continuously at different processing conditions in a dry powder coating equipment (towpregger), were processed into final composite parts in a specially developed prototype pultrusion equipment. The influence of the towpregger fiber pull speed and the furnace temperature on the polymer content of the final towpregs was determined. The towpregs' quality was also assessed using optical microscopy and scanning electron microscopy. They were then processed into composite profiles in the pultrusion machine, and the influence of the pull speed and dies' temperatures on their mechanical and other relevant physical properties was studied. Finally, the best processing window and the optimization of the final composite profiles are discussed.The authors acknowledge the support of the Institute for Polymers and Composites through Strategic Project-LA 25-2011-2012 (PEst-C/CTM/LA0025/2011)
The influence of the clay particles on the mechanical properties and fracture behavior of PLA/o-MMT composite films

In this study, calendered films of polylactic acid/organo-montmorillonite clay (PLA/o-MMT) were prepared and the influence of the clay particles' morphology on the mechanical properties and fracture behavior was evaluated. An image analysis was performed using transmission electron microscopy micrographs to complete the morphological study. The micrographs were taken from ultramicrotomic samples corresponding to the melting flow (MD) and transverse direction (TD) of the films. The micrographs revealed intercalated particles and tactoids, which were in accordance with the wide angle X-ray scattering patterns. Uniaxial tensile tests were performed in the MD and TD directions, finding a slight anisotropy in the films, which was associated with a low level of polymer chain orientation due to the calender processing. The fracture behavior was also evaluated in the MD and TD directions using deeply double-edge-notched tension (DDENT) specimens. The mechanical and fracture tests were evaluated on aging (brittle) and deaging (ductile) films by applying a thermal treatment that consisted of heating above the glass transition temperature of the PLA and subsequent quenching. For ductile PLA composite films, the reinforcement effect promoted by the clay particles was not so evident.Peer ReviewedPostprint (author’s final draft
A new extensional mixing element for improved dispersive mixing in twin-screw extrusion, part 2: experimental validation for immiscible polymer blends

In Part 1 of this work, we presented a novel static extensional mixing element (EME) for twin-screw extrusion
operations and validated the design in terms of the type of flow experienced by the melt upon dispersive mixing. In Part 2, we experimentally demonstrate the ability of the EME to yield improved dispersive mixing when compared with standard kneading-block-induced mixing for immiscible polypropylene/polystyrene blends of varying viscosity ratios between 0.3 and 10. The extensional flow characteristics of the EME improved the dispersion of polystyrene in the blends over all viscosity ratios, with improvements of 30% and above as measured by the cumulative area ratio measurements of polystyrene phases smaller than 1 μm2.
The improvement in dispersive mixing seen from the EME for high viscosity ratio blends opens up applications in other areas, such as dispersion of nanoparticles or in reactive extrusion operationsThe authors would like to thank Safa D. Jamali, Arman Boromand, Jesse L. Gadley, Patrick J. Harris, and Jonah C. Rosch for the helpful technical discussions during the design phases and experimental assistance. We would also like to thank Alpha Tool & Mold in Highland Heights, OH, for their fabrication work. We are also grateful to Saint-Gobain Ceramics, to the Center for Layered Polymeric Systems (CLiPS, NSF STC grant #0423914) and to NSF (grant CMMI #1246715), for the funding provided.info:eu-repo/semantics/updatedVersio
Local Versus Long-Range Diffusion Effects of Photoexcited States on Radiative Recombination in Organic–Inorganic Lead Halide Perovskites

Radiative recombination in thin films of the archetypical, high-performing perovskites CH₃NH₃PbBr₃ and CH₃NH₃PbI₃ shows localized regions of increased emission with dimensions ≈ 500 nm. Maps of the spectral emission line shape show narrower emission lines in high emission regions, which can be attributed to increased order. Excited states do not diffuse out of high emission regions before they decay, but are decoupled from nearby regions, either by slow diffusion rates or energetic barriers.Funding was supported by the Winton Program for the Physics of Sustainability and the EPSRC. M.V. thanks the Winton Programme for the Physics of Sustainability and the Cambridge Trust. C.M. acknowledges funding from a Clare College Junior Research Fellowship. G.D., S.C., and C.D. acknowledge funding from ERC under grant number 259619 PHOTO EM. F.D. acknowledges funding from a Herchel Smith Research Fellowship.This is the final version of the article. It first appeared from Wiley via http://dx.doi.org/10.1002/advs.20150013
High-Throughput Contact Flow Lithography

High-throughput fabrication of graphically encoded hydrogel microparticles is achieved by combining flow contact lithography in a multichannel microfluidic device and a high capacity 25 mm LED UV source. Production rates of chemically homogeneous particles are improved by two orders of magnitude. Additionally, the custom-built contact lithography instrument provides an affordable solution for patterning complex microstructures on surfaces.Novartis Institutes of Biomedical Research. Education OfficeNational Science Foundation (U.S.) (Grants CMMI-1120724 and DMR-1006147)United States. Army Research Office (Institute for Collaborative Biotechnologies. Grant W911NF-09-0001
Generating light from upper excited triplet states : a contribution to the indirect singlet yield of a polymer OLED, helping to exceed the 25% singlet exciton limit.

The mechanisms by which light is generated in an organic light emitting diode have slowly been elucidated over the last ten years. The role of triplet annihilation has demonstrated how the “spin statistical limit” can be surpassed, but it cannot account for all light produced in the most efficient devices. Here, a further mechanism is demonstrated by which upper excited triplet states can also contribute to indirect singlet production and delayed fluorescence. Since in a device the population of these TN states is large, this indirect radiative decay channel can contribute a sizeable fraction of the total emission measured from a device. The role of intra- and interchain charge transfer states is critical in underpinning this mechanism
High Performance Field Emitters

By compiling the largest meta-analysis to date, across a diverse range of materials, here we show that the work function of a material does not strongly impact on field electron emission performance, when only the work function is considered. Materials studied include 1D, 2D and 3D/bulk with a range in work function from 1.33 eV to 7.75 eV. We find that the turn-on electric fields show a stronger dependency on dimensionality than on work function, with 3D/bulk materials typically requiring an electric field twice as large as those of the one-dimensional and two-dimensional emitters.M.T.C. thanks the Oppenheimer Trust, Cambridge University, for generous financial support. This work was supported by an EPSRC Impact Acceleration grant and an Innovate UK Advanced Materials Feasibility Study award. CC thanks the EPSRC Centre for Doctoral Training in Ultra Precision.This is the final version of the article. It first appeared from Wiley via http://dx.doi.org/10.1002/advs.20150031
Reversing adhesion: A triggered release self-reporting adhesive

Here, the development of an adhesive is reported – generated via free radical polymerization – which can be degraded upon thermal impact within minutes. The degradation is based on a stimuli responsive moiety (SRM) that is incorporated into the network. The selected SRM is a hetero Diels-Alder (HDA) moiety that features three key properties. First, the adhesive can be degraded at relatively low temperatures (≈80 °C), second the degradation occurs very rapidly (less than 3 min), and third, the degradation of the network can readily be analyzed and quantified due to its self-reporting nature. The new reversible self-reporting adhesion system is characterized in detail starting from molecular studies of the retro HDA reaction. Moreover, the mechanical properties of the network, as well as the adhesion forces, are investigated in detail and compared to common methacrylate-based systems, demonstrating a significant decrease in mechanic stability at elevated temperatures. The current study thus represents a significant advance of the current state of the art for debonding on demand adhesives, making the system interesting for several fields of application including dental adhesives
Designing Colloidal Molecules with Microfluidics

International audienceThe creation of new colloidal materials involves the design of functional building blocks. Here, a microﬂ uidic method for designing building blocks one by one, at high throughput, with a broad range of shapes is introduced. The method exploits a coupling between hydrodynamic interactions and depletion forces that controls the conﬁ gurational dynamics of droplet clusters traveling in microﬂ uidic channels. Droplet clusters can be solidiﬁ ed in situ with UV. By varying the ﬂ ow parameters, clusters are prescribed a given size, geometry, chemical and/or magnetic heterogeneities enabling local bonding. Compact structures (chains, triangles, diamonds, tetrahedrons,...) and non-compact structures, such as crosses and T, difﬁ cult to obtain with current techniques are produced. Size dispersions are small (2%) and throughputs are high (30 000 h −1). The work opens a new pathway, based on microﬂ uidics, for designing colloidal building blocks with a potential to enable the creation of new materials
The role of local triplet excited states and d-a relative orientation in thermally activated delayed fluorescence : photophysics and devices.

Here, a comprehensive photophysical investigation of a the emitter molecule DPTZ-DBTO2, showing thermally activated delayed fluorescence (TADF), with near-orthogonal electron donor (D) and acceptor (A) units is reported. It is shown that DPTZ-DBTO2 has minimal singlet–triplet energy splitting due to its near-rigid molecular geometry. However, the electronic coupling between the local triplet (3LE) and the charge transfer states, singlet and triplet, (1CT, 3CT), and the effect of dynamic rocking of the D–A units about the orthogonal geometry are crucial for efficient TADF to be achieved. In solvents with low polarity, the guest emissive singlet 1CT state couples directly to the near-degenerate 3LE, efficiently harvesting the triplet states by a spin orbit coupling charge transfer mechanism (SOCT). However, in solvents with higher polarity the emissive CT state in DPTZ-DBTO2 shifts below (the static) 3LE, leading to decreased TADF efficiencies. The relatively large energy difference between the 1CT and 3LE states and the extremely low efficiency of the 1CT to 3CT hyperfine coupling is responsible for the reduction in TADF efficiency. Both the electronic coupling between 1CT and 3LE, and the (dynamic) orientation of the D–A units are thus critical elements that dictate reverse intersystem crossing processes and thus high efficiency in TADF
High-Performance Direct Methanol Fuel Cells with Precious-Metal-Free Cathode

Direct methanol fuel cells (DMFCs) hold great promise for applications ranging from portable power for electronics to transportation. However, apart from the high costs, current Pt-based cathodes in DMFCs suffer significantly from performance loss due to severe methanol crossover from anode to cathode. The migrated methanol in cathodes tends to contaminate Pt active sites through yielding a mixed potential region resulting from oxygen reduction reaction and methanol oxidation reaction. Therefore, highly methanol-tolerant cathodes must be developed before DMFC technologies become viable. The newly developed reduced graphene oxide (rGO)-based Fe-N-C cathode exhibits high methanol tolerance and exceeds the performance of current Pt cathodes, as evidenced by both rotating disk electrode and DMFC tests. While the morphology of 2D rGO is largely preserved, the resulting Fe-N-rGO catalyst provides a more unique porous structure. DMFC tests with various methanol concentrations are systematically studied using the best performing Fe-N-rGO catalyst. At feed concentrations greater than 2.0 m, the obtained DMFC performance from the Fe-N-rGO cathode is found to start exceeding that of a Pt/C cathode. This work will open a new avenue to use nonprecious metal cathode for advanced DMFC technologies with increased performance and at significantly reduced cost.open0
Chemically selective alternatives to photoferroelectrics for polarization-enhanced photocatalysis: the untapped potential of hybrid inorganic nanotubes

Linear-scaling density functional theory simulation of methylated imogolite nanotubes (NTs) elucidates the interplay between wall-polarization, bands separation, charge-transfer excitation, and tunable electrostatics inside and outside the NT-cavity. The results suggest that integration of polarization-enhanced selective photocatalysis and chemical separation into one overall dipole-free material should be possible. Strategies are proposed to increase the NT polarization for maximally enhanced electron–hole separation
High-Performance Heterostructured Cathodes for Lithium-Ion Batteries with a Ni-Rich Layered Oxide Core and a Li-Rich Layered Oxide Shell

The Ni-rich layered oxides with a Ni content of >0.5 are drawing much attention recently to increase the energy density of lithium-ion batteries. However, the Ni-rich layered oxides suffer from aggressive reaction of the cathode surface with the organic electrolyte at the higher operating voltages, resulting in consequent impedance rise and capacity fade. To overcome this difficulty, we present here a heterostructure composed of a Ni-rich LiNi0.7Co0.15Mn0.15O2 core and a Li-rich Li1.2&#8722; x Ni0.2Mn0.6O2 shell, incorporating the advantageous features of the structural stability of the core and chemical stability of the shell. With a unique chemical treatment for the activation of the Li2MnO3 phase of the shell, a high capacity is realized with the Li-rich shell material. Aberration-corrected scanning transmission electron microscopy (STEM) provides direct evidence for the formation of surface Li-rich shell layer. As a result, the heterostructure exhibits a high capacity retention of 98% and a discharge-voltage retention of 97% during 100 cycles with a discharge capacity of 190 mA h g&#8722;1 (at 2.0&#8211;4.5 V under C/3 rate, 1C = 200 mA g&#8722;1).ope
Brown adipose tissue bioenergetics: a new methodological approach

The rediscovery of brown adipose tissue (BAT) in humans and its capacity to oxidize fat and dissipate energy as heat has put the spotlight on its potential as a therapeutic target in the treatment of several metabolic conditions including obesity and diabetes. To date the measurement of bioenergetics parameters has required the use of cultured cells or extracted mitochondria with the corresponding loss of information in the tissue context. Herein, we present a method to quantify mitochondrial bioenergetics directly in BAT. Based on XF Seahorse Technology, we assessed the appropriate weight of the explants, the exact concentration of each inhibitor in the reaction, and the specific incubation time to optimize bioenergetics measurements. Our results show that BAT basal oxygen consumption is mostly due to proton leak. In addition, BAT presents higher basal oxygen consumption than white adipose tissue and a positive response to b-adrenergic stimulation. Considering the whole tissue and not just subcellular populations is a direct approach that provides a realistic view of physiological respiration. In addition, it can be adapted to analyze the effect of potential activators of thermogenesis, or to assess the use of fatty acids or glucose as a source of energy
Giant Faraday Rotation through Ultrasmall Fe^0_n Clusters in Superparamagnetic FeO-SiO_2 Vitreous Films

Magnetooptical (MO) glasses and, in particular, Faraday rotators are becoming key components in lasers and optical information processing, light switching, coding, filtering, and sensing. The common design of such Faraday rotator materials follows a simple path: high Faraday rotation is achieved by maximizing the concentration of paramagnetic ion species in a given matrix material. However, this approach has reached its limits in terms of MO performance; hence, glass-based materials can presently not be used efficiently in thin film MO applications. Here, a novel strategy which overcomes this limitation is demonstrated. Using vitreous films of xFeO·(100 − x)SiO_2, unusually large Faraday rotation has been obtained, beating the performance of any other glassy material by up to two orders of magnitude. It is shown that this is due to the incorporation of small, ferromagnetic clusters of atomic iron which are generated in line during laser deposition and rapid condensation of the thin film, generating superparamagnetism. The size of these clusters underbids the present record of metallic Fe incorporation and experimental verification in glass matrice
Polyelectrolyte-enrobed cancer cells in view of personalized immune-therapy

Targeting the immune system with a personalized vaccine containing cues derived from the patient's malignancy might be a promising approach in the fight against cancer. It includes neo-antigens as well as nonmutated tumor antigens, preferentially leading to an immune response that is directed to a broader range of epitopes compared to strategies involving a single antigen. Here, this paper reports on an elegant method to encapsulate whole cancer cells into polyelectrolyte particles. Porous and nonaggregated microparticles containing dead cancer cells are obtained by admixing mannitol and live cancer cells with oppositely charged polyelectrolytes, dextran sulfate (anionic polysaccharide), and poly-l-arginine (cationic polypeptide) prior to atomization into a hot air stream. It shows that the polyelectrolyte-enrobed cancer cells, upon redispersion in phosphate buffered saline buffer, are stable and do not release cell proteins in the supernatant. In vitro experiments reveal that the particles are nontoxic and strongly increase uptake of cell lysate by dendritic cells. In vitro assessment of antigen presentation by dendritic cells reveal the potential of the polyelectrolyte-enrobed cancer cells as promotors of antigen cross-presentation. Finally, it is demonstrated that the immunogenicity can be enhanced by surface adsorption of a polymer-substituted TLR7-agonist
Synthesis of High-Quality Graphene and Hexagonal Boron Nitride Monolayer In-Plane Heterostructure on Cu–Ni Alloy

Graphene/hexagonal boron nitride (h-BN) monolayer in-plane heterostructure offers a novel material platform for both fundamental research and device applications. To obtain such a heterostructure in high quality via controllable synthetic approaches is still challenging. In this work, in-plane epitaxy of graphene/h-BN heterostructure is demonstrated on Cu–Ni substrates. The introduction of nickel to copper substrate not only enhances the capability of decomposing polyaminoborane residues but also promotes graphene growth via isothermal segregation. On the alloy surface partially covered by h-BN, graphene is found to nucleate at the corners of the as-formed h-BN grains, and the high growth rate for graphene minimizes the damage of graphene-growth process on h-BN lattice. As a result, high-quality graphene/h-BN in-plane heterostructure with epitaxial relationship can be formed, which is supported by extensive characterizations. Photodetector device applications are demonstrated based on the in-plane heterostructure. The success will have important impact on future research and applications based on this unique material platform
The Way towards Ultrafast Growth of Single-Crystal Graphene on Copper

The exceptional properties of graphene make it a promising candidate in the development of next-generation electronic, optoelectronic, photonic and photovoltaic devices. A holy grail in graphene research is the synthesis of large-sized single-crystal graphene, in which the absence of grain boundaries guarantees its excellent intrinsic properties and high performance in the devices. Nowadays, most attention has been drawn to the suppression of nucleation density by using low feeding gas during the growth process to allow only one nucleus to grow with enough space. However, because the nucleation is a random event and new nuclei are likely to form in the very long growth process, it is difficult to achieve industrial-level wafer-scale or beyond (e.g. 30 cm in diameter) single-crystal graphene. Another possible way to obtain large single-crystal graphene is to realize ultrafast growth, where once a nucleus forms, it grows up so quickly before new nuclei form. Therefore ultrafast growth provides a new direction for the synthesis of large single-crystal graphene, and is also of great significance to realize large-scale production of graphene films (fast growth is more time-efficient and cost-effective), which is likely to accelerate various graphene applications in industry