Publications

Li₉S₃N is a novel Li–metal barrier coating for all-solid-state batteries. The conductivity is greatly improved by <graphic xmlns:xlink="http://www.w3.org/1999/xlink" id="ugt1" xlink:href="http://pubs.rsc.org/TA/2015/c5ta05432j/c5ta05432j-t1..gif"/> substitution.

The authors point out that by defining several notions of robustness for an attractor network, it is possible to augment previous results about the AdaTron algorithm by explicit values for the robustness of the optimal weights. It is shown that the symmetry of a problem is reflected by the invariance of the optimal weights. This enables one to deduce that a convex corner detection, using a discrete-time cellular neural network (DTCNN), cannot be accomplished with just one clock cycle, and an improved convex corner detector is proposed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Sustainability is a key requirement for partnership success and a major challenge for such organizations. Despite the critical importance of sustainability to the success of community health partnerships and the many threats to sustainability, there is little evidence that would provide partnerships with clear guidance on long-term viability. This article attempts to (1) develop a conceptual model of sustainability in community health partnerships and (2) identify potential determinants of sustainability using comparative qualitative data from four partnerships from the Community Care Network (CCN) Demonstration Program. Based on a grounded theory examination of qualitative data from the CCNevaluation, the authors hypothesize that there are five primary attributes/ activities of partnerships leading to consequential value and eventually to sustainability of collaborative capacity. They include outcomes-based advocacy, vision-focus balance, systems orientation, infrastructure development, and community linkages. The context in which the partnership operates provides the conditions for determining the appropriateness and relative impact of each of the factors related to creating consequential value in the partnership.

Abstract The Fischer–Tropsch process, or the catalytic hydrogenation of carbon monoxide (CO), produces long chain hydrocarbons and offers an alternative to the use of crude oil for chemical feedstocks. The observed size dependence of cobalt (Co) catalysts for the Fischer–Tropsch reaction was studied with colloidally prepared Co nanoparticles and a chemical transient kinetics reactor capable of measurements under non‐steady‐state conditions. Co nanoparticles of 4.3 nm and 9.5 nm diameters were synthesized and tested under atmospheric pressure conditions and H 2 /CO=2. Large differences in carbon coverage (Θ C ) were observed for the two catalysts: the 4.3 nm Co catalyst has a Θ C less than one while the 9.5 nm Co catalyst supports a Θ C greater than two. The monomer units present on the surface during reaction are identified as single carbon species for both sizes of Co nanoparticles, and the major CO dissociation site is identified as the B 5 ‐B geometry. The difference in activity of Co nanoparticles was found to be a result of the structure sensitivity caused by the loss of these specific types of sites at smaller nanoparticle sizes.

The goal of this research is elucidation of the molecular mechanism for the unique photosystem II (PSII) damage and repair cycle in chloroplasts. A frequently occurring, irreversible photooxidative damage inhibits the PSII charge separation reaction and stops photosynthesis. The chloroplast PSII repair process rectifies this adverse effect by selectively removing and replacing the photoinactivated D1/32-kD reaction center protein (the chloroplast-encoded psbA gene product) from the massive (&gt;1,000 kD) water-oxidizing and O(2)-evolving PSII holocomplex. DNA insertional mutagenesis in the model organism Chlamydomonas reinhardtii was applied for the isolation and characterization of rep27, a repair-aberrant mutant. Gene cloning and biochemical analyses in this mutant resulted in the identification of REP27, a nuclear gene encoding a putative chloroplast-targeted protein, which is specifically required for the completion of the D1 turnover process but is not essential for the de novo biogenesis and assembly of the PSII holocomplex in this model green alga. The REP27 protein contains two highly conserved tetratricopeptide repeats, postulated to facilitate the psbA mRNA cotranslational insertion of the nascent D1 protein in the existing PSII core template. Elucidation of the PSII repair mechanism may reveal the occurrence of hitherto unknown regulatory and catalytic reactions for the selective in situ replacement of specific proteins from within multiprotein complexes.

As the distribution of the video over the Internet becomes main- stream and its consumption moves from the computer to the TV screen, user expectation for high quality is constantly increasing. In this context, it is crucial for content providers to understand if and how video quality affects user engagement and how to best invest their resources to optimize video quality. This paper is a first step towards addressing these questions. We use a unique dataset that spans different content types, including short video on demand (VoD), long VoD, and live content from popular video con- tent providers. Using client-side instrumentation, we measure quality metrics such as the join time, buffering ratio, average bitrate, rendering quality, and rate of buffering events.

Unstructured Networks have been used extensively in P2P search systems today primarily for file sharing. These networks exploit heterogeneity in the network and offload most of the query processing load to more powerful nodes. As an alternative to unstructured networks, there have been recent proposals for using inverted indexes on structured networks for searching. These structured networks, otherwise known as distributed hash tables (DHTs), guarantee recall and are well suited for locating rare items. However, they may incur significant bandwidth for keyword-based searches. This paper performs a measurement study of Gnutella, a popular unstructured network used for file sharing. We focus primarily on studying Gnutella's search performance and recall, especially in light of recent ultrapeer enhancements. Our study reveals significant query overheads in Gnutella ultra-peers, and the presence of queries that may benefit from the use of DHTs. Based on our study, we propose the use of a hybrid search infrastructure to improve the search coverage for rare items and present some preliminary performance results

Olivine LiFePO 4 is believed to form two-phase equilibrium between the FePO 4 (FP) and LiFePO 4 (LFP) phases in large particles. However, in rechargeable batteries, LFP is nanosized to overcome the low electric conductivity. The phase transformation behavior of nanosized LFP remains poorly understood. To address this issue, we have developed models and an electrochemical simulation framework for Li intercalation dynamics at particle/microstructural level to examine the phase transformation dynamics of LFP nanoparticles. The charge/discharge processes of Li-ion batteries involve several coupled physical mechanisms that occur within complex electrode microstructures. To simulate the electrochemical processes at particle/microstructural level, we developed an innovative technique that allows us to efficiently simulate electrochemical (de)intercalation processes at length scales ranging from electrode particle to complex electrode microstructures. In this presentation, we will discuss the smoothed-boundary-method electrochemical simulation framework, which straightforwardly couples the multiple physical mechanisms in the different phases of a composite electrode and incorporates the complex electrode geometries, as well as its applications. For demonstration, we used an experimentally obtained LiCoO 2 cathode microstructure and corresponding material properties as simulation input [1]. We applied this simulation framework to investigate the phase-separation dynamics of LFP-nanoparticle electrodes. We first simulated a two-particle system to elucidate the detailed interparticle interactions upon (de)lithiation [2], and identified a unique process of interparticle phase separation. The simulation was extended to a collection of a modest number of LFP nanoparticles, where the particles were not contacting one another and formed a dilute agglomerate [3]. The simulation revealed a group-by-group interparticle phase separation process at low currents. In a further extension, we investigated the dynamics in a densely packed LFP-nanoparticle agglomerate [3], in which direct contact between particles was taken into account. In the dense agglomerate, we found that interparticle phase separation can still prevail at high currents due to the direct Li redistribution across particle interfaces. Finally, we included the consideration of particle-size dependent equilibrium potential into the model [4]. The simulation showed an asymmetry of phase transformation between lithiation and delithiation of an electrode at low currents. Acknowledgement: This material is based upon work supported as part of NECCES, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Numbers DE-SC0001294 and DE-SC0012583. [1] H.-C. Yu et al., in preparation. [2] B. Orvanonos et al., J Electrochem Soc, 162 (2015) A965 [3] B. Orvananos et al., Electrochimca Acta, 137 (2014) 245 [4] B. Orvananos et al., submitted to J Electrochem Soc.

Metabolic engineering and synthetic biology are predicated on the precise control of gene expression. As synthetic biology expands beyond model organisms, more tools will be required that function robustly in a wide range of bacterial hosts. The pGinger family of plasmids constitutes 43 plasmids that will enable both constitutive and inducible gene expression in a wide range of nonmodel Proteobacteria .

Freeze casting has proven to be a versatile processing route to fabricate bio-inspired (“nacre-like”) hybrid composites that exhibit unique combinations of strength and toughness (damage-tolerance). To date, however, the effects of small changes in the architecture of such composites on their mechanical properties have been poorly investigated. Here we examine the influence of microstructural features such as ceramic/polymer ratio, layer thickness, and presence of bridges between ceramic lamellae, on the mechanical performance of the resulting composites. To this end, we compare the flexural strength and resistance to failure of a suite of silicon carbide/polymethyl methacrylate (SiC/PMMA) layered composites made by polymer infiltration of freeze-cast SiC scaffolds with various architectures. Our composite structures all show an increasing fracture resistance with crack extension (rising R-curve behavior) due to extrinsic toughening mechanisms such as uncracked-ligament bridging, inelastic deformation of ductile layers, lamellae pull out and ceramic bridge fracture. We show that a fine tuning of the composite architecture can lead to SiC/PMMA samples with a dendritic morphology, which exhibit the best strength and toughness. Specifically, the presence of ceramic bridges connecting the lamellae is seen to provide a strengthening effect similar to the mineral bridges between aragonite platelets in nacre, where they prevent debonding and limit platelet sliding; additionally, the fracture of these bridges between lamellae during crack extension is a potent toughening mechanism, thereby conferring optimal damage tolerance to the material.