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Träfflista för sökning "WFRF:(Nuzzo G.) "

Sökning: WFRF:(Nuzzo G.)

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1.
  • Aad, G, et al. (författare)
  • 2015
  • swepub:Mat__t
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2.
  • Schael, S., et al. (författare)
  • Electroweak measurements in electron positron collisions at W-boson-pair energies at LEP
  • 2013
  • Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 532:4, s. 119-244
  • Forskningsöversikt (refereegranskat)abstract
    • Electroweak measurements performed with data taken at the electron positron collider LEP at CERN from 1995 to 2000 are reported. The combined data set considered in this report corresponds to a total luminosity of about 3 fb(-1) collected by the four LEP experiments ALEPH, DELPHI, 13 and OPAL, at centre-of-mass energies ranging from 130 GeV to 209 GeV. Combining the published results of the four LEP experiments, the measurements include total and differential cross-sections in photon-pair, fermion-pair and four-fermion production, the latter resulting from both double-resonant WW and ZZ production as well as singly resonant production. Total and differential cross-sections are measured precisely, providing a stringent test of the Standard Model at centre-of-mass energies never explored before in electron positron collisions. Final-state interaction effects in four-fermion production, such as those arising from colour reconnection and Bose Einstein correlations between the two W decay systems arising in WW production, are searched for and upper limits on the strength of possible effects are obtained. The data are used to determine fundamental properties of the W boson and the electroweak theory. Among others, the mass and width of the W boson, m(w) and Gamma(w), the branching fraction of W decays to hadrons, B(W -> had), and the trilinear gauge-boson self-couplings g(1)(Z), K-gamma and lambda(gamma), are determined to be: m(w) = 80.376 +/- 0.033 GeV Gamma(w) = 2.195 +/- 0.083 GeV B(W -> had) = 67.41 +/- 0.27% g(1)(Z) = 0.984(-0.020)(+0.018) K-gamma - 0.982 +/- 0.042 lambda(gamma) = 0.022 +/- 0.019. (C) 2013 Elsevier B.V. All rights reserved.
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3.
  • Schael, S, et al. (författare)
  • Precision electroweak measurements on the Z resonance
  • 2006
  • Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
  • Forskningsöversikt (refereegranskat)abstract
    • We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLID experiment using a polarised beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarised asymmetries. The mass and width of the Z boson, m(Z) and Gamma(Z), and its couplings to fermions, for example the p parameter and the effective electroweak mixing angle for leptons, are precisely measured: m(Z) = 91.1875 +/- 0.0021 GeV, Gamma(Z) = 2.4952 +/- 0.0023 GeV, rho(l) = 1.0050 +/- 0.0010, sin(2)theta(eff)(lept) = 0.23153 +/- 0.00016. The number of light neutrino species is determined to be 2.9840 +/- 0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, m(t) = 173(+10)(+13) GeV, and the mass of the W boson, m(W) = 80.363 +/- 0.032 GeV. These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of m(t) and m(W), the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than 285 GeV at 95% confidence level. (c) 2006 Elsevier B.V. All rights reserved.
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4.
  • Le Roch, Sarah, et al. (författare)
  • European survey on criteria of aesthetics for periodontal evaluation: The ESCAPE study
  • 2019
  • Ingår i: Journal of Clinical Periodontology. - : Wiley. - 0303-6979 .- 1600-051X. ; 46:11, s. 1116-1123
  • Tidskriftsartikel (refereegranskat)abstract
    • © 2019 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd Objective: The ESCAPE multicentre survey was designed to (a) compare the agreement of three relevant aesthetic scoring systems among different centres, and (b) evaluate the reproducibility of each question of the questionnaires. Materials and Methods: EFP centres (n=14) were involved in an e-survey. Forty-two participants (28 teachers, 14 postgraduate students) were asked to score the one-year aesthetic outcomes of photographs using the Before–After Scoring System (BASS), the Pink Esthetic Score (PES) and the Root coverage Esthetic Score (RES). Mean values of kappa statistics performed on each question were provided to resume global agreement of each method. Results: Between teachers, a difference of kappa≥0.41 (p=.01) was found for BASS (75%) and PES (57%). Similarly, RES (84%) and PES (57%) were different (p<.001). No difference was found between BASS (75%) and RES (84%). No difference was found between students, whatever the scoring system. Questions of each scoring system showed differences in their reproducibility. Conclusions: The outcomes of this study indicate that BASS and RES scoring systems are reproducible tools to evaluate aesthetic after root coverage therapies between different centres. Among the various variables, lack of scar, degree of root coverage, colour match and gingival margin that follows the CEJ show the best reliability.
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6.
  • Petronico, Aaron, et al. (författare)
  • Solid-Liquid Lithium Electrolyte Nanocomposites Derived from Porous Molecular Cages
  • 2018
  • Ingår i: Journal of the American Chemical Society. - : AMER CHEMICAL SOC. - 0002-7863 .- 1520-5126. ; 140:24, s. 7504-7509
  • Tidskriftsartikel (refereegranskat)abstract
    • We demonstrate that solid-liquid nanocomposites derived from porous organic cages are effective lithium ion electrolytes at room temperature. A solid-liquid electrolyte nanocomposite (SLEN) fabricated from a LiTFSI/DME electrolyte system and a porous organic cage exhibits ionic conductivity on the order of 1 x 10(-3) S cm(-1). With an experimentally measured activation barrier of 0.16 eV, this composite is characterized as a superionic conductor. Furthermore, the SLEN displays excellent oxidative stability up to 4.7 V vs Li/Li+. This simple three-component system enables the rational design of electrolytes from tunable discrete molecular architectures.
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7.
  • Potter, Maggie M., et al. (författare)
  • Autonomous Light Management in Flexible Photoelectrochromic Films Integrating High Performance Silicon Solar Microcells
  • 2020
  • Ingår i: ACS Applied Energy Materials. - : AMER CHEMICAL SOC. - 2574-0962. ; 3:2, s. 1540-1551
  • Tidskriftsartikel (refereegranskat)abstract
    • Commercial smart window technologies for dynamic light and heat management in building and automotive environments traditionally rely on electrochromic (EC) materials powered by an external source. This design complicates building-scale installation requirements and substantially increases costs for applications in retrofit construction. Self-powered photoelectrochromic (PEC) windows are an intuitive alternative wherein a photovoltaic (PV) material is used to power the EC device, which modulates the transmission of the incident solar flux. The PV component in this application must be sufficiently transparent and produce enough power to efficiently modulate the EC device transmission. Here, we propose Si solar microcells (mu-cells) that are (i) small enough to be visually transparent to the eye and (ii) thin enough to enable flexible PEC devices. Visual transparency is achieved when Si mu-cells are arranged in high pitch (i.e., low-integration density) form factors while maintaining the advantages of a single-crystalline PV material (i.e., long lifetime and high performance). Additionally, the thin dimensions of these Si mu-cells enable fabrication on flexible substrates to realize flexible PEC devices. The current work demonstrates this concept using WO3 as the EC material and V2O5 as the ion storage layer, where each component is fabricated via sol-gel methods that afford improved prospects for scalability and tunability in comparison to thermal evaporation methods. The EC devices display fast switching times, as low as 8 s, with a modulation in transmission as high as 33%. Integration with two Si mu-cells in series (affording a 1.12 V output) demonstrates an integrated PEC module design with switching times of less than 3 min and a modulation in transmission of 32% with an unprecedented EC:PV areal ratio.
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8.
  • Wang, C., et al. (författare)
  • 3D Printing High-Resolution Conductive Elastomeric Structures with a Solid Particle-Free Emulsion Ink
  • 2022
  • Ingår i: Advanced Engineering Materials. - : Wiley. - 1438-1656 .- 1527-2648. ; 24:3
  • Tidskriftsartikel (refereegranskat)abstract
    • Fabricating complex structures on micro- and mesoscales is a critical aspect in the design of advanced sensors and soft electronics. However, soft lithographic methods offer an important approach to fabricating such structures, the progress in the field of additive manufacturing (e.g., 3D printing) offers methods of fabrication with much more material complexity. The rheological complexity of the printing material, however, often dictates the limitations of printing. In particular, the challenges involved in synthesizing printing materials that can enable shape retention at smaller scales (<100 μm), yet be conductive, limits many applications of 3D printing to soft microelectronics. Herein, a printing-centered approach using a novel particle-free conductive emulsion ink is presented. This approach separates the printing and polymerization of a conductive monomer (pyrrole) and renders a novel ink that is used to print filaments with heretofore impossible to realize 3D feature dimensions and build structures with high shape retention. The printability of the ink is evaluated, and post-treatment properties assessed. Multidirectional strain sensors are printed using the emulsion ink to illustrate an exemplary application in soft electronics. 
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9.
  • Enright, Michael J., et al. (författare)
  • Role of Atomic Structure on Exciton Dynamics and Photoluminescence in NIR Emissive InAs/InP/ZnSe Quantum Dots
  • 2022
  • Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 126:17, s. 7576-7587
  • Tidskriftsartikel (refereegranskat)abstract
    • The development of bright, near-infrared-emissive quantum dots (QDs) is a necessary requirement for the realization of important new classes of technology. Specifically, there exist significant needs for brighter, heavy metal-free, near-infrared (NIR) QDs for applications with high radiative efficiency that span diverse applications, including down-conversion emitters for high-performance luminescent solar concentrators. We use a combination of theoretical and experimental approaches to synthesize bright, NIR luminescent InAs/InP/ZnSe QDs and elucidate fundamental material attributes that remain obstacles for development of near-unity NIR QD luminophores. First, using Monte Carlo ray tracing, we identify the atomic and electronic structural attributes of InAs core/shell, NIR emitters, whose luminescence properties can be tailored by synthetic design to match most beneficially those of high-performance, single-band-gap photovoltaic devices based on important semiconductor materials, such Si or GaAs. Second, we synthesize InAs/InP/ZnSe QDs based on the optical attributes found to maximize LSC performance and develop methods to improve the emissive qualities of NIR emitters with large, tunable Stokes ratios, narrow emission linewidths, and high luminescence quantum yields (here reaching 60 +/- 2%). Third, we employ atomistic electronic structure calculations to explore charge carrier behavior at the nanoscale affected by interfacial atomic structures and find that significant exciton occupation of the InP shell occurs in most cases despite the InAs/InP type I bulk band alignment. Furthermore, the density of the valence band maximum state extends anisotropically through the (111) crystal planes to the terminal InP surfaces/interfaces, indicating that surface defects, such as unpassivated phosphorus dangling bonds, located on the (111) facets play an outsized role in disrupting the valence band maximum and quenching photoluminescence.
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10.
  • Hickey, C. D., et al. (författare)
  • Influence of buttermilk powder or buttermilk addition on phospholipid content, chemical and bio-chemical composition and bacterial viability in Cheddar style-cheese
  • 2017
  • Ingår i: Food Research International. - : Elsevier BV. - 0963-9969 .- 1873-7145. ; 102, s. 748-758
  • Tidskriftsartikel (refereegranskat)abstract
    • The effect of buttermilk powder addition post-curd formation or buttermilk addition to cheese milk on total and individual phospholipid content, chemical composition, enzyme activity, microbial populations and microstructure within Cheddar-style cheese was investigated. Buttermilk or buttermilk powder addition resulted in significant increases in total phospholipid content and their distribution throughout the cheese matrix. Addition of 10% buttermilk powder resulted in higher phospholipid content, moisture, pH and salt in moisture levels, and lower fat, fat in dry matter, L. helveticus and non-starter bacteria levels in cheeses. Buttermilk powder inclusion resulted in lower pH 4.6/Soluble Nitrogen (SN) levels and significantly lower free amino acid levels in 10% buttermilk powder cheeses. Buttermilk addition provided a more porous cheese microstructure with greater fat globule coalescence and increased free fat pools, while also increasing moisture and decreasing protein, fat and pH levels. Addition of buttermilk in liquid or powdered form offers potential for new cheeses with associated health benefits. © 2017 Elsevier Ltd
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11.
  • Kottwitz, Matthew, et al. (författare)
  • Local Structure and Electronic State of Atomically Dispersed Pt Supported on Nanosized CeO2
  • 2019
  • Ingår i: ACS Catalysis. - : AMER CHEMICAL SOC. - 2155-5435. ; 9:9, s. 8738-8748
  • Tidskriftsartikel (refereegranskat)abstract
    • Single atom catalysts (SACs) have shown high activity and selectivity in a growing number of chemical reactions. Many efforts aimed at unveiling the structure-property relationships underpinning these activities and developing synthesis methods for obtaining SACs with the desired structures are hindered by the paucity of experimental methods capable of probing the attributes of local structure, electronic properties, and interaction with support-features that comprise key descriptors of their activity. In this work, we describe a combination of experimental and theoretical approaches that include photon and electron spectroscopy, scattering, and imaging methods, linked by density functional theory calculations, for providing detailed and comprehensive information on the atomic structure and electronic properties of SACs. This characterization toolbox is demonstrated here using a model single atom Pt/CeO2 catalyst prepared via a sol-gel-based synthesis method. Isolated Pt atoms together with extra oxygen atoms passivate the (100) surface of nanosized ceria. A detailed picture of the local structure of Pt nearest environment emerges from this work involving the bonding of isolated Pt2+ ions at the hollow sites of perturbed (100) surface planes of the CeO2 support, as well as a substantial (and heretofore unrecognized) strain within the CeO2 lattice in the immediate vicinity of the Pt centers. The detailed information on structural attributes provided by our approach is the key for understanding and improving the properties of SACs.
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12.
  • Kottwitz, Matthew, et al. (författare)
  • Single Atom Catalysts: A Review of Characterization Methods
  • 2021
  • Ingår i: Chemistry-Methods. - : John Wiley and Sons Inc. - 2628-9725. ; 1:6, s. 278-294
  • Forskningsöversikt (refereegranskat)abstract
    • Single atom catalysts (SACs) harbor a potential to exceed nanoparticle catalysts in terms of activity, stability and selectivity in a growing number of chemical reactions. Although their investigation is attracting significant attention, important fundamental questions focusing on key physicochemical properties of SACs (e. g., structure – property relationships, structural dynamics, reaction-driven restructuring) remain unanswered. A main challenge for research in the field is how to reliably characterize the environments of single atoms in the presence of complicating factors such as low weight loadings, strong metal-support interactions, and atomic and multiscale heterogeneity of bonding in the single atom sites. This review addresses this challenge – identifying catalytically relevant features of physicochemical properties of single atoms (charge state, electronic structure, atomic configuration, bonding interactions with a support) and surveying advanced tools/methods for characterizing them. The review places a strong emphasis on multimodal methods exploiting X-ray absorption, emission and photoelectron spectroscopies, and provides several examples from the authors’ research that demonstrate their use as powerful tools for SAC characterization.
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13.
  • Lehman, S E, et al. (författare)
  • Biocompliant Composite Au/pHEMA Plasmonic Scaffolds for 3D Cell Culture and Noninvasive Sensing of Cellular Metabolites
  • 2020
  • Ingår i: Advanced Healthcare Materials. - : Wiley-VCH Verlag. - 2192-2640 .- 2192-2659.
  • Tidskriftsartikel (refereegranskat)abstract
    • The field of 3D printing is an area of active research, with a substantial focus given to the design and construction of customized tools for applications in technology. There exists a particular need in these developing areas of opportunity for new multi-functional soft materials that are biologically compatible for the growth and directed culturing of cells. Herein, a composite material consisting of gold nanoparticles with useful plasmonic properties embedded within a highly hydrophilic poly-2-hydroxyethylmethacrylate matrix is described and characterized. This composite material serves dual functions as both host framework scaffold for cell lines such as pre-osteoblasts as well as a plasmonic biosensor for in situ measurements of living cells. The plasmonic properties of this system are characterized as a function of the material properties and related to compositional features of the material through a proposed light-directed mechanism. This chemistry provides a tunable, 3D printable plasmonic composite material of encapsulated gold nanoparticles in a biologically-compliant, acrylate-based hydrogel matrix. Surface-enhanced Raman scattering studies of 3D-microcultures supported by the scaffolds are carried out and the strong influence of perm-selective molecular diffusion in its analytical responses is established. Most notably, specific, largely hydrophilic, cellular metabolites are detected within the supported live cultures. 
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14.
  • Li, Yuanyuan, et al. (författare)
  • Active sites of atomically dispersed Pt supported on Gd-doped ceria with improved low temperature performance for CO oxidation
  • 2023
  • Ingår i: Chemical Science. - : Royal Society of Chemistry (RSC). - 2041-6520 .- 2041-6539. ; 14:44, s. 12582-12588
  • Tidskriftsartikel (refereegranskat)abstract
    • “Single-atom” catalysts (SACs) have been the focus of intense research, due to debates about their reactivity and challenges toward determining and designing “single-atom” (SA) sites. To address the challenge, in this work, we designed Pt SACs supported on Gd-doped ceria (Pt/CGO), which showed improved activity for CO oxidation compared to its counterpart, Pt/ceria. The enhanced activity of Pt/CGO was associated with a new Pt SA site which appeared only in the Pt/CGO catalyst under CO pretreatment at elevated temperatures. Combined X-ray and optical spectroscopies revealed that, at this site, Pt was found to be d-electron rich and bridged with Gd-induced defects via an oxygen vacancy. As explained by density functional theory calculations, this site opened a new path via a dicarbonyl intermediate for CO oxidation with a greatly reduced energy barrier. These results provide guidance for rationally improving the catalytic properties of SA sites for oxidation reactions.
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15.
  • Li, Y., et al. (författare)
  • Complex structural dynamics of nanocatalysts revealed in Operando conditions by correlated imaging and spectroscopy probes
  • 2015
  • Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 6
  • Tidskriftsartikel (refereegranskat)abstract
    • Understanding how heterogeneous catalysts change size, shape and structure during chemical reactions is limited by the paucity of methods for studying catalytic ensembles in working state, that is, in operando conditions. Here by a correlated use of synchrotron X-ray absorption spectroscopy and scanning transmission electron microscopy in operando conditions, we quantitatively describe the complex structural dynamics of supported Pt catalysts exhibited during an exemplary catalytic reaction-ethylene hydrogenation. This work exploits a microfabricated catalytic reactor compatible with both probes. The results demonstrate dynamic transformations of the ensemble of Pt clusters that spans a broad size range throughout changing reaction conditions. This method is generalizable to quantitative operando studies of complex systems using a wide variety of X-ray and electron-based experimental probes.
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16.
  • Li, Yuanyuan, et al. (författare)
  • Dynamic structure of active sites in ceria-supported Pt catalysts for the water gas shift reaction
  • 2021
  • Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 12:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Oxide-supported noble metal catalysts have been extensively studied for decades for the water gas shift (WGS) reaction, a catalytic transformation central to a host of large volume processes that variously utilize or produce hydrogen. There remains considerable uncertainty as to how the specific features of the active metal-support interfacial bonding-perhaps most importantly the temporal dynamic changes occurring therein-serve to enable high activity and selectivity. Here we report the dynamic characteristics of a Pt/CeO2 system at the atomic level for the WGS reaction and specifically reveal the synergistic effects of metal-support bonding at the perimeter region. We find that the perimeter Pt-0-O vacancy-Ce3+ sites are formed in the active structure, transformed at working temperatures and their appearance regulates the adsorbate behaviors. We find that the dynamic nature of this site is a key mechanistic step for the WGS reaction. Revealing the structure and dynamics of active sites is essential to understand catalytic mechanisms. Here the authors demonstrate the dynamic nature of perimeter Pt-0-O vacancy-Ce3+ sites in Pt/CeO2 and the key effects of their dynamics on the mechanism of the water gas shift reaction.
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17.
  • Liu, Claire, et al. (författare)
  • Multifunctional Materials Strategies for Enhanced Safety of Wireless, Skin-Interfaced Bioelectronic Devices
  • 2023
  • Ingår i: Advanced Functional Materials. - : Wiley. - 1616-301X .- 1616-3028. ; 33:34
  • Tidskriftsartikel (refereegranskat)abstract
    • Many recently developed classes of wireless, skin-interfaced bioelectronic devices rely on conventional thermoset silicone elastomer materials, such as poly(dimethylsiloxane) (PDMS), as soft encapsulating structures around collections of electronic components, radio frequency antennas and, commonly, rechargeable batteries. In optimized layouts and device designs, these materials provide attractive features, most prominently in their gentle, noninvasive interfaces to the skin even at regions of high curvature and large natural deformations. Past studies, however, overlook opportunities for developing variants of these materials for multimodal means to enhance the safety of the devices against failure modes that range from mechanical damage to thermal runaway. This study presents a self-healing PDMS dynamic covalent matrix embedded with chemistries that provide thermochromism, mechanochromism, strain-adaptive stiffening, and thermal insulation, as a collection of attributes relevant to safety. Demonstrations of this materials system and associated encapsulation strategy involve a wireless, skin-interfaced device that captures mechanoacoustic signatures of health status. The concepts introduced here can apply immediately to many other related bioelectronic devices.
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18.
  • McCracken, Joselle M., et al. (författare)
  • 3D-Printed Hydrogel Composites for Predictive Temporal (4D) Cellular Organizations and Patterned Biogenic Mineralization
  • 2019
  • Ingår i: Advanced Healthcare Materials. - : WILEY. - 2192-2640 .- 2192-2659. ; 8:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Materials chemistries for hydrogel scaffolds that are capable of programming temporal (4D) attributes of cellular decision-making in supported 3D microcultures are described. The scaffolds are fabricated using direct-ink writing (DIW)-a 3D-printing technique using extrusion to pattern scaffolds at biologically relevant diameters (<= 100 mu m). Herein, DIW is exploited to variously incorporate a rheological nanoclay, Laponite XLG (LAP), into 2-hydroxyethyl methacrylate (HEMA)-based hydrogels-printing the LAP-HEMA (LH) composites as functional modifiers within otherwise unmodified 2D and 3D HEMA microstructures. The nanoclay-modified domains, when tested as thin films, require no activating (e.g., protein) treatments to promote robust growth compliances that direct the spatial attachment of fibroblast (3T3) and preosteoblast (E1) cells, fostering for the latter a capacity to direct long-term osteodifferentiation. Cell-to-gel interfacial morphologies and cellular motility are analyzed with spatial light interference microscopy (SLIM). Through combination of HEMA and LH gels, high-resolution DIW of a nanocomposite ink (UniH) that translates organizationally dynamic attributes seen with 2D gels into dentition-mimetic 3D scaffolds is demonstrated. These analyses confirm that the underlying materials chemistry and geometry of hydrogel nanocomposites are capable of directing cellular attachment and temporal development within 3D microcultures-a useful material system for the 4D patterning of hydrogel scaffolds.
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19.
  • McCracken, Joselle M., et al. (författare)
  • Ionic Hydrogels with Biomimetic 4D-Printed Mechanical Gradients : Models for Soft-Bodied Aquatic Organisms
  • 2019
  • Ingår i: Advanced Functional Materials. - : WILEY-V C H VERLAG GMBH. - 1616-301X .- 1616-3028. ; 29:28
  • Tidskriftsartikel (refereegranskat)abstract
    • Direct-ink writing (DIW), a rapidly growing and advancing form of additive manufacturing, provides capacities for on-demand tailoring of materials to meet specific requirements for final designs. The penultimate challenge faced with the increasing demand of customization is to extend beyond modification of shape to create 4D structures, dynamic 3D structures that can respond to stimuli in the local environment. Patterning material gradients is foundational for assembly of 4D structures, however, there remains a general need for useful materials chemistries to generate gray scale gradients via DIW. Here, presented is a simple materials assembly paradigm using DIW to pattern ionotropic gradients in hydrogels. Using structures that architecturally mimic sea-jelly organisms, the capabilities of spatial patterning are highlighted as exemplified by selectively programming the valency of the ion-binding agents. Spatial gradients, when combined with geometry, allow for programming the flexibility and movement of iron oxide nanoparticle-loaded ionotropic hydrogels to generate 4D-printed structures that actuate in the presence of local magnetic fields. This work highlights approaches to 4D design complexity that exploits 3D-printed gray-scale/gradient mechanics.
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20.
  • Nelson, A. Z., et al. (författare)
  • Designing and transforming yield-stress fluids
  • 2019
  • Ingår i: Current opinion in solid state & materials science. - : Elsevier. - 1359-0286 .- 1879-0348. ; 23:5
  • Forskningsöversikt (refereegranskat)abstract
    • We review progress in designing and transforming multi-functional yield-stress fluids and give a perspective on the current state of knowledge that supports each step in the design process. We focus mainly on the rheological properties that make yield-stress fluids so useful and the trade-offs which need to be considered when working with these materials. Thinking in terms of “design with” and “design of” yield-stress fluids motivates how we can organize our scientific understanding of this field. “Design with” involves identification of rheological property requirements independent of the chemical formulation, e.g. for 3D direct-write printing which needs to accommodate a wide range of chemistry and material structures. “Design of” includes microstructural considerations: conceptual models relating formulation to properties, quantitative models of formulation-structure-property relations, and chemical transformation strategies for converting effective yield-stress fluids to be more useful solid engineering materials. Future research directions are suggested at the intersection of chemistry, soft-matter physics, and material science in the context of our desire to design useful rheologically-complex functional materials.
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21.
  • Pan, Chengsi, et al. (författare)
  • Energy Storage Mechanisms in High-Capacity Graphitic C3N4 Cathodes for Al-Ion Batteries
  • 2020
  • Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 124:19, s. 10288-10297
  • Tidskriftsartikel (refereegranskat)abstract
    • Al-ion batteries are a promising alternative to lithium-ion batteries because of the unique advantages of the Al anode, such as low cost and high specific capacities. Cathodes developed for these batteries, however, suffer from various problems, which include low discharge voltages with rapid capacity fade (e.g., V2O5) and unclear speciation of the Al intercalation mechanism with insufficient capacity (e.g., graphite). The lack of ideal cathode materials is currently a major challenge for Al-ion batteries. Here, a high-capacity layered organic cathode composed of graphitic carbon nitride (g-C3N4) is developed for Al-ion batteries. Full cells constructed using g-C3N4 paired with an Al metal in an AlCl3/[EMIm]Cl electrolyte showed an open-circuit potential of 1.9 V and a capacity of 90 mAh/g cycled at 0.1 C. This battery also exhibits a stable capacity of 75 mAh/g cycled at 0.2 C in a long-term test (500 cycles). The data show that the layered porous structure of the organic cathode material facilitates a reversible deintercalation of [AlCl4](-) anions, substituting them for Cl- in a more oxidized form of the g-C3N4. The data further illustrate that the anion shuttle is associated with a conversion between N and N+. states at the tertiary N
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22.
  • Potter, Maggie M., et al. (författare)
  • Silicon Heterojunction Microcells
  • 2021
  • Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 13:38, s. 45600-45608
  • Tidskriftsartikel (refereegranskat)abstract
    • We report the design, fabrication, and characterization of silicon heterojunction microcells, a new type of photovoltaic cell that leverages high-efficiency bulk wafers in a microscale form factor, while also addressing the challenge of passivating microcell sidewalls to mitigate carrier recombination. We present synthesis methods exploiting either dry etching or laser cutting to realize microcells with native oxide-based edge passivation. Measured microcell performance for both fabrication processes is compared to that in simulations. We characterize the dependence of microcell open-circuit voltage (V-oc) on the cell area-perimeter ratio and examine synthesis processes that affect edge passivation quality, such as sidewall damage removal, the passivation material, and the deposition technique. We report the highest Si microcell V-oc to date (588 mV, for a 400 mu m x 400 mu m x 80 mu m device), demonstrate V-oc improvements with deposited edge passivation of up to 55 mV, and outline a pathway to achieve microcell efficiencies surpassing 15% for such device sizes.
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23.
  • Sang, Lingzi, et al. (författare)
  • Understanding the Effect of Interlayers at the Thiophosphate Solid Electrolyte/Lithium Interface for All-Solid-State Li Batteries
  • 2018
  • Ingår i: Chemistry of Materials. - : AMER CHEMICAL SOC. - 0897-4756 .- 1520-5002. ; 30:24, s. 8747-8756
  • Tidskriftsartikel (refereegranskat)abstract
    • All-solid-state Li-ion batteries afford possibilities to enhance battery safety while improving their energy and power densities. Current challenges for achieving high-performance all-solid-state batteries with long cycle life include shorting resulting predominantly from Li dendrite formation and infiltration through the solid electrolyte (SE) and increases in cell impedance induced by SE decomposition at the SE/electrode interface. In this work, we evaluate the electrochemical properties of two interlayer materials, Si and LixAl(2-x/3)O3 (LiAlO), at the Li7P3S11 (LPS)/Li interface. Compared to the Li/LPS/Li symmetric cells in absence of interlayers, the presence of Si and LiAlO both significantly enhance the cycle number and total charge passing through the interface before failures resulting from cell shorting. In both cases, the noted improvements were accompanied by cell impedances that had increased substantially. The data reveal that both interlayers prevent the direct exposure of LPS to the metallic Li and therefore eliminate the intrinsic LPS decomposition that occurs at Li surfaces before electrochemical cycling. After cycling, a reduction of LPS to Li2S occurs at the interface when a Si interlayer is present; LiAlO, which functions to drop the potential between Li and LPS, suppresses LPS decomposition processes. The relative propensities toward SE decomposition follows from the electrochemical potentials at the interface, which are dictated by the identities of the interlayer materials. This work provides new insights into the phase dynamics associated with specific choices for SE/electrode interlayer materials and the requirements they impose for realizing high efficiency, long lasting all-solid-state batteries.
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24.
  • Taylor, Jay M, et al. (författare)
  • Biomimetic and Biologically Compliant Soft Architectures via 3D and 4D Assembly Methods : A Perspective
  • 2022
  • Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 34:16, s. 2108391-
  • Tidskriftsartikel (refereegranskat)abstract
    • Recent progress in soft material chemistry and enabling methods of 3D and 4D fabrication—emerging programmable material designs and associated assembly methods for the construction of complex functional structures—is highlighted. The underlying advances in this science allow the creation of soft material architectures with properties and shapes that programmably vary with time. The ability to control composition from the molecular to the macroscale is highlighted—most notably through examples that focus on biomimetic and biologically compliant soft materials. Such advances, when coupled with the ability to program material structure and properties across multiple scales via microfabrication, 3D printing, or other assembly techniques, give rise to responsive (4D) architectures. The challenges and prospects for progress in this emerging field in terms of its capacities for integrating chemistry, form, and function are described in the context of exemplary soft material systems demonstrating important but heretofore difficult-to-realize biomimetic and biologically compliant behaviors. 
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25.
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26.
  • van der Hofstad, Tom G. J., et al. (författare)
  • Carrier Recombination in Polymer Fullerene Solar Cells Probed by Reversible Exchange of Charge between the Active Layer and Electrodes Induced by a Linearly Varying Voltage
  • 2013
  • Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society. - 1932-7447 .- 1932-7455. ; 117:7, s. 3210-3220
  • Tidskriftsartikel (refereegranskat)abstract
    • The use of a voltage pulse that varies linearly with time and that is symmetric in time around t = 0 allows for simultaneous determination of (photo)capacitance and (photo)conductance of polymer solar cells. From the measured capacitance, an average density of reversibly extractable carriers is determined, and the result is compared to numerical drift-diffusion simulations. Results are in agreement with large charge densities near the contacts that can be exchanged with the electrode in a thermodynamically reversible manner upon changing the voltage. The combined determination of capacitance and conductance yields a relaxation time tau(rel) for photogenerated charge carriers. Results on thermally annealed poly(3-hexylthiopene):fullerene bulk heterojunction solar cells indicate tau(rel) similar to 2 mu s, limited by extraction and not significantly affected by bimolecular recombination under intensities up to 1 sun. In contrast, for small bandgap poly(diketopyrrolopyrrole-alt-quinquethiophene)-fullerene solar cells with similar to 5% power conversion efficiency, tau(rel) is limited by bimolecular recombination. This illustrates the need for very fast charge transport rates to avoid losses due to bimolecular recombination in solar cells with high charge generation rates. Conclusions from the charge exchange experiments are confirmed by time domain measurements using pulsed illumination.
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27.
  • Wang, C., et al. (författare)
  • 3D Particle-Free Printing of Biocompatible Conductive Hydrogel Platforms for Neuron Growth and Electrophysiological Recording
  • 2021
  • Ingår i: Advanced Functional Materials. - : Wiley. - 1616-301X .- 1616-3028. ; 31:14
  • Tidskriftsartikel (refereegranskat)abstract
    • Electrically conductive 3D periodic microscaffolds are fabricated using a particle-free direct ink writing approach for use as neuronal growth and electrophysiological recording platforms. A poly (2-hydroxyethyl methacrylate)/pyrrole ink, followed by chemical in situ polymerization of pyrrole, enables hydrogel printing through nozzles as small as 1 µm. These conductive hydrogels can pattern complex 2D and 3D structures and have good biocompatibility with test cell cultures (≈94.5% viability after 7 days). Hydrogel arrays promote extensive neurite outgrowth of cultured Aplysia californica pedal ganglion neurons. This platform allows extracellular electrophysiological recording of steady-state and stimulated electrical neuronal activities. In summation, this 3D conductive ink printing process enables the preparation of biocompatible and micron-sized structures to create customized in vitro electrophysiological recording platforms.
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28.
  • Wang, Haodong, et al. (författare)
  • Aliovalent Doping of CeO2 Improves the Stability of Atomically Dispersed Pt
  • 2021
  • Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 13:44, s. 52736-52742
  • Tidskriftsartikel (refereegranskat)abstract
    • Atomically dispersed supported catalysts hold considerable promise as catalytic materials. The ability to employ and stabilize them against aggregation in complex process environments remains a key challenge to the elusive goal of 100% atom utilization in catalysis. Herein, using a Gd-doped ceria support for atomically dispersed surface Pt atoms, we establish how the combined effects of aliovalent doping and oxygen vacancy generation provide dynamic mechanisms that serve to enhance the stability of supported single-atom configurations. Using correlated, in situ X-ray absorption, photoelectron, and vibrational spectroscopy methods for the analysis of samples on the two types of support (with and without Gd doping), we establish that the Pt atoms are located proximal to Gd dopants, forming a speciation that serves to enhance the thermal stability of Pt atoms against aggregation.
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29.
  • Wang, L.-L., et al. (författare)
  • Origin of bulklike structure and bond length disorder of Pt37 and Pt6Ru31 clusters on carbon : Comparison of theory and experiment
  • 2006
  • Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 128:1, s. 131-142
  • Tidskriftsartikel (refereegranskat)abstract
    • We describe a theoretical analysis of the structures of self-organizing nanoparticles formed by Pt and Ru-Pt on carbon support. The calculations provide insights into the nature of these metal particle systems-ones of current interest for use as the electrocatalytic materials of direct oxidation fuel cells- and clarify complex behaviors noted in earlier experimental studies. With clusters deposited via metalloorganic Pt or PtRu5 complexes, previous experiments [Nashner et al. J. Am. Chem. Soc. 1997, 119, 7760, Nashner et al. J. Am. Chem. Soc. 1998, 120, 8093, Frenkel et al. J. Phys. Chem. B 2001, 105, 12689] showed that the Pt and Pt-Ru based clusters are formed with fcc(111)-stacked cuboctahedral geometry and essentially bulklike metal-metal bond lengths, even for the smallest (few atom) nanoparticles for which the average coordination number is much smaller than that in the bulk, and that Pt in bimetallic [PtRu5] clusters segregates to the ambient surface of the supported nanoparticles. We explain these observations and characterize the cluster structures and bond length distributions using density functional theory calculations with graphite as a model for the support. The present study reveals the origin of the observed metal-metal bond length disorder, distinctively different for each system, and demonstrates the profound consequences that result from the cluster/carbon-support interactions and their key role in the structure and electronic properties of supported metallic nanoparticles. © 2006 American Chemical Society.
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30.
  • Wu, Yunyun, et al. (författare)
  • Thermoplastic Elastomers for Wireless, Skin-Interfaced Electronic, and Microfluidic Devices
  • 2023
  • Ingår i: Advanced Materials Technologies. - : Wiley. - 2365-709X. ; 8:19
  • Tidskriftsartikel (refereegranskat)abstract
    • Wireless, skin-interfaced electronic and microfluidic devices have the potential to replace wired, bulky, and cumbersome technologies for personal and clinical health monitoring, allowing care to extend from hospital settings to the home. For use on skin, these devices commonly employ silicone-based thermoset elastomers (TSEs) as layers that encapsulate the electronics or serve as molded microchannels for biofluid (e.g., sweat) capture, storage, and analysis. Barriers to commercial adoption of such devices include difficulties in use of these elastomers in conventional practices for mass manufacturing. Their relatively high cost and inability to allow for recycling represent additional disadvantages. By contrast, thermoplastic elastomers (TPEs) are fully compatible with industrial-scale manufacturing processes, low in cost, and recyclable. Like TSEs, TPEs are soft, stretchable, flexible, and optically transparent, while possessing other properties well-suited for applications in wireless, skin-interfaced devices. Herein, the characteristics, processing, and application techniques for three commercially available TPEs, including two thermoplastic polyurethanes as encapsulation layers for a wireless skin hydration sensor and one thermoplastic styrenic block copolymer for a microfluidic sweat analysis platform, are reported. The results demonstrate that TPEs can be effectively integrated into these classes of devices, as a compelling alternative to TSEs, as a mass-manufacturable, sustainable materials option.
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31.
  • Yoder, Mikayla A., et al. (författare)
  • Semiconductor Nanomembrane Materials for High-Performance Soft Electronic Devices
  • 2018
  • Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 140:29, s. 9001-9019
  • Forskningsöversikt (refereegranskat)abstract
    • The development of methods to synthesize and physically manipulate extremely thin, single-crystalline inorganic semiconductor materials, so-called nano membranes, has led to an almost explosive growth of research worldwide into uniquely enabled opportunities for their use in new "soft" and other unconventional form factors for high-performance electronics. The unique properties that nanomembranes afford, such as their flexibility and lightweight characteristics, allow them to be integrated into electronic and optoelectronic devices that, in turn, adopt these unique attributes. For example, nanomembrane devices are able to make conformal contact to curvilinear surfaces and manipulate strain to induce the self-assembly of various 3D nano/micro device architectures. Further, thin semiconductor materials (e.g., Si-nanomembranes, transition metal dichalcogenides, and phosphorene) are subject to the impacts of quantum and other size-dependent effects that in turn enable the manipulation of their bandgaps and the properties of electronic and optoelectronic devices fabricated from them. In this Perspective, nanomembrane synthesis techniques and exemplary applications of their use are examined. We specifically describe nanomembrane chemistry exploiting high-performance materials, along with precise/high-throughput techniques for their manipulation that exemplify their growing capacities to shape outcomes in technology. Prominent challenges in the chemistry of these materials are presented along with future directions that might guide the development of next generation nanomembrane-based devices.
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