Acknowledges Financial Support Research Articles

Long-term High-density Microelectrode Array Recordings Evidence Stability of Neuron Locations in Organotypic Hippocampus Slices

Long-term High-density Microelectrode Array Recordings Evidence Stability of Neuron Locations in Organotypic Hippocampus Slices

Lithium Ion Dynamics in Amorphous Li-Si Electrochemically Prepared from Semiconductor Grade, Monocrystalline Silicon - an NMR Study about Local Structures and Li+ Self-Diffusivity

Silicon is one of the most promising anode materials for lithium-based rechargeable batteries. Provided the volume changes during Li uptake can be brought under control, Li ion diffusivity is expected to crucially determine the performance of such energy storage systems. Therefore, studying diffusion properties in amorphous Li-Si underpins applied research that is being directed towards the development of powerful storage devices. So far, only little information is available on Li self-diffusion in amorphous Si. Here, we used 7Li NMR spectroscopy [1] to precisely quantify microscopic activation energies and Li jump rates in amorphous Li-Si which is primarily formed if monocrystalline Si is lithiated electrochemically. Our results reveal relatively fast Li diffusivity with an average activation energy for long-range ion transport as high as ca. 0.65 eV; jump rates turn out to be in the order of 2.5 × 105 1/s at 246 K, see also ref. [2]. Comparisons with data from laboratory frame NMR relaxometry, which is sensitive to more localized ion hopping, points to complex dynamics that is most likely governed by non-exponential motional correlation functions originating from a large distribution of activation energies. Noteworthy, a second sample, which is a mixture of amorphous Li-Si and metastable, crystalline Li15Si4 that forms at lower discharge potentials, points to slightly enhanced Li diffusivity (0.51 eV). Interestingly, first high-resolution 6Li MAS NMR experiments on X-ray amorphous Li-Si, which have been carried out using isotope enriched samples, indicate the presence of structural motifs that resemble those of Li12Si7. The data obtained might help optimizing Li-based silicon batteries whose performance critically depend on fast Li-ion transport. Acknowledgement Financial support by the Federal Ministry of Science, Research and Economy and the National Foundation for Research, Technology and Development is gratefully acknowledged.

Combining Nitrogen Precursors in Synthesis of Non-Precious Metal ORR Catalysts with Improved Fuel Cell Performance

Platinum and platinum-alloy oxygen reduction reaction (ORR) catalysts have been implemented in the prototype, and by now also in commercial fuel cell power systems for automotive applications, successfully meeting the demanding conditions of relatively low temperature (80°C) and high acidity operating conditions of the polymer electrolyte fuel cell (PEFC). However, due to the high price of Pt, the catalyst cost is projected to account for as much as a half of the total PEFC stack cost.1 In this context, the potential replacement of Pt-based catalysts, especially in the fuel cell cathode, with non-precious metal catalysts (NPMCs) is expected to significantly reduce PEFC stack cost. Achieving such a cost benefit is, however, contingent upon reaching sufficient activity and durability with NPMC for the ORR, a requirement that the electrocatalysis research community has been striving to meet. In this presentation, we expand upon the idea of combining nitrogen precursors during NPMC synthesis to improve the performance and performance durability of non-precious metal ORR catalysts. Previously, we introduced a new non-precious metal ORR catalyst derived from two nitrogen precursors with different decomposition temperatures: easily decomposing cyanamide (CM) and more thermally stable polyaniline (PANI).2 In this approach, CM acts as an efficient pore-forming agent that allows for the formation of a highly porous structure, which in particular benefits the high-current response of the resulting electrocatalyst. Compared to the alternative approach utilizing metal-organic frameworks (MOFs),3,4 the use of cyanamide promises a very significant reduction in the NPMC cost, without sacrificing ORR activity. In an effort to further improve the PEFC performance of the two nitrogen-precursor NPMCs, we have explored approaches involving the use of ammonia treatment, the addition of various carbon supports, and inclusion of multiple transition metals. In this presentation, we will summarize the results of these studies, which have involved the extensive use of characterization techniques, such as X-ray photoelectron spectroscopy, scanning electron microscopy, scanning transmission electron microscopy, X-ray diffraction, surface area/pore distribution measurements, and nano-scale X-ray computed tomography. In the conclusion, we will also define critical factors for enhancing the performance of NPMCs in the PEFC cathode and outline directions for future research. Acknowledgement Financial support for this research by DOE-EERE through Fuel Cell Technologies Office is gratefully acknowledged. Microscopy research supported through a user project at ORNL’s Center for Nanomaterials Sciences, which is an Office of Science User Facility. References Spendelow et al., DOE Fuel Cell Technologies Office, Fuel Cell System Cost-2013, (2013).Hoon T. Chung et al., “Combined nitrogen precursor approach to develop highly active non-precious metal oxygen reduction reaction catalyst.” in preparation.S. Ma et al., “Cobalt Imidazolate Framework as Precursor for Oxygen Reduction Reaction Electrocatalysts,” Chem. Eur. J. 17, 2063 (2011).Proietti et al., “Iron-based cathode catalyst with enhanced power density in polymer electrolyte membrane fuel cells,” Nat. Commun. 2, 416 (2011)

Excitation and damping of broadband kink waves in the solar corona

D.J.P. acknowledges financial support from STFC. I.D.M. acknowledges support of a Royal Society University Research Fellowship. The research leading to these results has also received funding from the European Commission Seventh Framework Programme (FP7/ 2007−2013) under the grant agreement SOLSPANET (project No. 269299, www.solspanet.eu/solspanet).

Impact of Cationic Impurities on Low-Pt Loading PEFC Cathodes

Many demanding issues still need to be addressed before full commercialization of PEFC can take place, and cationic contamination is one of the major obstacles. Foreign cations diminish proton conductivity and affect water content of the polymer electrolyte membrane, increasing the cell performance losses. Foreign cations may originate from the soil, road salts, corrosion of the cell, stack, components, as well as coolant fluids, and balance of plant (BoP) components. Among the cations, Ca2+ receives special attention because it is one of the most prevalent elements within our planet. In this work, sulfate (SO4 2−) is selected as the anion due to its compatibility with the PEFC, considering sulfuric acid is a common catalyst and electrode characterization solution. The cation solution injection at cathode was employed to better control on dosage and to emulate cationic contamination of fuel cells under actual conditions [1]. To test the real world condition and obtain the consistent data, the commercially available the low loading catalyst (Pt: 0.1 mg /cm2) coated membrane (GORE Inc.) was used. During the contaminant test, cell was maintained at 80◦C with anode H2 and cathode air flow rates of 1.75 slpm and 1.66 slpm, respectively. The CaSO4 solution of 5 ppm of total concentration was injected (130 µl/min) at the cathode inlet using nebulizer [1]. Overall, the anode/cathode RH was maintained at 25%/125%, and the anode/cathode outlet back pressure was maintained at 10 kPa/100 kPa gauge pressure (∼1.5 psig/15 psig, ambient pressure 1 atm), respectively. Figure 1 shows the cell voltage decay during the constant-current hold tests (1 A cm-2) with and without Ca 2+ solution injection. It is observed that during the initial injection of water there is no significant performance loss, whereas while injecting the CaSO4 solution (5 ppm) steep fall in cell voltage is observed. In order to get a clear understanding on factors that contribute to the severe voltage loss during the CaSO4 injection, pressure of the cathode inlet and outlet are monitored (Figure 1 (b)). These data reveal that the increased pressure over the time is due to salt precipitation in the cathode gas diffusion layer and the flow field, and the pressure gain trend is correlated with the voltage degradation. The cell test was stopped after 350 h of CaSO4injection due to blocking of the cathode outlet. The polarization curves were obtained before and after the injection of CaSO4(Figure 2), a sharp fall in voltage was observed in the case of end of test (EOT ) curve, which indicates a very severe mass transport loss due to blocking of the cathode outlet [1-3]. These studies confirm that apart from the contaminant effect in polymer electrolyte membranes and catalyst layer’s ionomer, there is a severe impact that comes from the salt precipitation at gas diffusion layer and flow field plates. In addition, the effect of contaminant on catalyst support corrosion, membrane conductivity loss over the time also performed. Acknowledgement Financial support from the Department of Energy (DOE)-EERE, DE-EE0000467 (University of Hawaii, prime contractor, Jean St-Pierre, PI) is greatly acknowledged. Reference X. Wang, J. Qi, O. Ozdemir, A. Uddin, U. Pasaogullari, L. Bonville, and T. Molter, J. Electrochem. Soc., 161, F1006 (2014).M. A. Uddin, X. Wang, J. Qi, M. O. Ozdemir, L. Bonville, U. Pasaogullari, and T. Molter, ECS Trans., 61(12), 49 (2014).M. A. Uddin, J. Qi, M. O. Ozdemir, L. Bonville, U. Pasaogullari, and T. Molter, ECS Trans., 61(12), 37 (2014). Figure 1

Graphene Oxide Based Non Precious Metal Catalysts for Oxygen Reduction Reaction in Alkaline Media

The commercialization and widespread of polymer electrolyte fuel cells (PEFCs) has been limited by the high cost of Pt-based catalysts used in both PEFC anode and cathode. Recently, non-precious metal catalysts (NPMCs) have demonstrated high volumetric activity, low peroxide yield, and stability[1-2] and appear as potential candidates for the replacement of Pt-based oxygen reduction reaction (ORR) catalysts in the PEFC cathode. State-of-the-art NPMCs are typically synthesized from highly heterogeneous precursors[1,3,4], making understanding of the ORR active site in such catalysts particularly arduous. Catalysts based on graphene and graphene-oxide (GO) are more homogeneous and possess properties such as good chemical stability, excellent conductivity, and more importantly, can potentially be functionalized in a controlled manner[5]. GO inherently has a high defect density and can be modified with various functional moieties, e.g. carboxyl, hydroxyl, and epoxy groups using various synthesis techniques such as Hummers or Hoffmans methods. The desire to have a high defect density arises from the possibility that defect sites may serve as niches for the chemical doping of heteroatoms, such as nitrogen (N) that have been proven to play a critical role in the overall performance of NPMCs. Further, the N-doped sites might serve as anchors for the coordination of transition metal atoms such as Fe, leading to the formation of the ORR active sites. In this work, we have synthesized GO using different chemical routes and, subsequently, treated it with different drying strategies and finally doped it with ammonia at various temperatures (500°C-900°C). The electrochemical performance of the synthesized catalysts in oxygen reduction reaction was measured using RDE. In a 0.5 M H2SO4 electrolyte, a half-wave potential of 0.70 V and low peroxide formation were obtained. Conversely, in a 0.1 M NaOH electrolyte, a half-wave potential of 0.85 V was observed. Lower peroxide yields were observed when a drying treatment was part of the synthesis process. A detailed ICP-MS study identified ppm levels of Mn and Fe in the sample, possibly due to the intrinsic GO synthesis method used. Results obtained using other characterization techniques, such as Raman and XPS, will be presented to further understand the role of the metal and nitrogen doping in the performance of GO-based catalysts. These first results indicate high performance of treated GO-based NPMCs in both acidic and alkaline media. Although, we have demonstrated effective oxygen reduction activity and have a better understanding of GO-based catalysts, we are now focusing our efforts on the progressive addition of different metal precursors such as Co and Ni. Acknowledgement Financial support from the Los Alamos National Laboratory, Laboratory-Directed Research and Development (LDRD) is gratefully acknowledged.

Study of Inexpensive Li2Fe1-XMnxSiO4 Cathode Materials Synthesised Using Abundant Materials By Conventional Methods

Introduction Electrochemical storage units such as batteries and capacitors are used to store electrical energy for a wide range of applications. Different battery chemistries can be selected depending on their applications. The last decades, Li ion batteries have been widely introduced in e.g. hybrid and electrical vehicles. In the Li ion battery, the active electrode materials typically consist of metal oxide as the cathode and graphite as the anode where both have the ability to intercalate Li ions. For a more widespread use of Li ion batteries, either price has to decrease or the performance must be enhanced. Capacity can be increased by different means, such as replacing graphite with silicon by different methods and/or by changing the cathode materials. However, more effort should be focused on the cathode electrode chemistry, since this electrode has higher cost, use less environmentally benign materials and have a lower capacity compared to the anode. The introduction of LiFePO4has partly solved this problem, by removing the expensive, toxic and less abundant metals. However, this cathode material has challenges related to poor electronic conductivity and introduction of carbon and the importance of nanosized particles make the process more complex and expensive. The orthosilicates Li2(Fe, Mn, Co)SiO4 have been proposed as a promising family of cathode materials with possible additional benefits compared to LiFePO4 such as two available Li ions per formula unit for charge transport and better stability due to the SiO4 group. However, the orthosilicates with the even lower conductivity compared to LiFePO4and challenges related to the existence of several stable crystallographic polymorphs must be solved. Preferably this should be accomplished using inexpensive processing routes and precursors. Here, we present possible ways to accomplish this by using raw materials readily available in Norway, combined with conventional processing routes. The cathode materials are compared with similar materials synthesized by other complex routes. Experimental Li2Fe1-xMnxSiO4/C composites where prepared by mixing Li2CO3, iron and/or manganese source, silica source and carbon source. The different sources were Fe3O4 submicron powders and Fe-oxalateMn-oxide based dust / Mn-oxide chemical grade.Fused silica and silica waste from Si productionSucrose and glucose. The pressed pellets were heat treated in an argon atmosphere at optimized temperature and time to form as phase pure active cathode material as possible. The composites were examined for phase purity (XRD) and morphology (SEM and TEM). The electrochemical performance Li2Fe1-xMnxSiO4 cathode materials was studied using a CR2016 coin cell consisting of a Li foil anode, Celgard 2320 separator and 1.0M LiPF6in 3:7 EC:DEC electrolyte. Charge/discharge behavior was studied by galvanostatic cycling to evaluate the charge capacity and stability while the insertion and extraction reactions were studied by cyclic voltammetry. The electrochemical characteristics of the different batteries are discussed and related to the synthesis techniques and different precursors of the cathodes. Acknowledgement Financial support is gratefully acknowledged from the Research Council of Norway RENERGI program, grant number 216469/E20.

Electrochemical Separation and Purification of Astatine for Radiopharmaceutical Application

The second longest lived isotope Astatine (211At: T1/2=7.5 h), is one the most promising α-emitters for targeted cancer radiotherapy. The liquid/liquid extraction method has been shown to provide good separation of 211At from bismuth metal. However, of the liquid/liquid (L/L) extraction (separation) steps [1] used in the current manual isolation procedure presents a significant challenge due to the nature of the diisopropyl ether / hydrochloric acid (DIPE/HCl) and diisopropyl ether / sodium hydroxide (DIPE/NaOH) mixtures. The present work is focused on to evaluate the feasibility of electrochemical methods in the purification of 211At. This approach will be an alternative to hydrogen astatide (H211At) wet distillation. At the present time, Bi (III) is considered the primary contaminant from which 211At must be electrochemically purified. The initial electrochemical studies were conducted with iodine as an astatine segregate in bismuth solution. As the concentration of astatine in the original solution is much lower than micro molar levels, there are two different approaches have been adopted; (i) separation of bismuth from the original solution [Ref 1; step 4] through electrodeposition and (ii) direct extraction of iodine from the original solution [Ref 1; step 3 or 4]. Figure 1(a) shows the cyclic voltammograms (CV) for bismuth on various substrate electrodes; namely Pt, Au and glassy carbon (GC). In these, the GC substrate found to be the suitable martial than others, which could be due to surface nature of carbon. In the case second approach, initially, iodide separation was carried out without bismuth in an acidic electrolyte with various concentrations of iodide to identify the suitable substrate material and minimum separation levels. Figure 1(b) shows the model CV for iodide on Pt electrode, surprisingly iodine deposit was also observed at the working electrode. Conversely, there are no characteristic electrochemical peaks and deposits were observed for GC and Au. This study indicates iodide can be extracted with Pt electrodes and Pt catalyzes the reactions. Acknowledgements Financial support from the Department of Energy (DOE) is greatly acknowledged. Selvarani Ganesan is thankful for subcontract from the Pacific Northwest National Laboratory (Contract No. 244236; PI: Matthew J O'Hara). Reference E.R. Balkin, D.K. Hamlin, K. Gagnon, M.-K Chyan, S. Pal, S. Watanabe, and D.S. Wilbur, Appl. Sci., 3 (2013) 636-655. Figure 1

Nanostructured (Mg,M)2SiO4 As Cathode Material in Mg Ion Batteries

Rechargeable Li-ion batteries are already widely used, and the dominating solution for automotive as well as portable, high-power applications due to the superior power density. However, several challenges of Li-ion battery technology are yet to be overcome, e.g. with respect to cost, resource availability, safety issues related to risk of thermal runaway of batteries and the limited temperature window of Li-ion batteries due to electrolyte deterioration at low temperatures. Although expected to dominate the portable battery market in the foreseeable future, the above mentioned drawbacks of Li-based batteries mean they have limited suitability in several markets, including stationary energy storage systems and auxiliary power applications where low cost and high reliability under a wide temperature range are more important than low weight and high power density. There is therefore a need for development of new battery types, specifically aimed at low cost markets. Batteries based on magnesium and other divalent metal ions, with the option of transferring two electrons, compared to the one electron transferred in Li-ion batteries, were introduced around 2000 by Aurbach et al.[1] and represent a promising solution for future low cost, high energy density batteries. Rechargeable Mg-batteries are not yet commercially available, but have a theoretical energy density in the range of 100 Wh/kg[2] for Chevrel-phase cathodes and up to 500 Wh/kg for MgMnSiO4 cathodes[3]. Still, fundamental research is needed in order to produce high-performance batteries which are also stable and recyclable. In this aspect, an interdisciplinary approach covering modeling, innovative material synthesis routes and advanced experimental characterization techniques is a powerful combination which is herein proposed for the development of low cost novel Mg-ion batteries. Such developments will be beneficial for a wide range of applications, mainly stationary, that require use of batteries, such as for storage of renewable energy from intermittent energy sources (solar, wind and wave), stand-alone power systems, telecommunication base stations, auxiliary power, etc. In this work, selected (Mg,M)2SiO4 (M=Mn or Co) materials are synthesized through an advanced sol-gel route as well as flame spray pyrolysis, aiming to obtain enhanced electrical conductivity. The developed cathode materials are characterized electrochemically by using Mg alloys as the anode and a state-of-the art electrolyte. In-situ X-ray diffraction (XRD) is used to characterize phase evolution in the materials during cycling. The effect of different synthesis methods on morphology, phase purity, crystal structure and electrochemical properties will be presented. [1] D. Aurbach, Lu, Z., Schechter, A., Gofer, Y., Gizbar, H., Turgeman, R., Cohen, Y., Moshkovich, M., Levi, E., Nature 2000, 407, 724-727. [2] D. Aurbach, Y. Gofer, Z. Lu, A. Schechter, O. Chusid, H. Gizbar, Y. Cohen, V. Ashkenazi, M. Moshkovich, R. Turgeman, E. Levi, Journal of Power Sources 2001, 97-98, 28-32. [3] Z. Z. Feng, J. Yang, Y. Nuli, J. L. Wang, X. J. Wang, Z. X. Wang, Electrochemistry Communications 2008, 10, 1291-1294. Acknowledgements Financial support is gratefully acknowledged from the Research Council of Norway, grant number 221785/F20.

An Approach for Highly Porous Non-Precious Metal Catalyst Synthesis for Polymer Electrolyte Fuel Cell Cathodes

Polymer electrolyte fuel cells (PEFCs) are electrochemical devices that convert chemical energy into electricity for a variety of applications, the most notable of which is transportation. The integration of PEFCs at scale for transportation applications however has been hindered due to the high price of platinum (Pt) that is the state-of-the-art catalyst for the oxygen reduction reaction (ORR) on the cathode. Replacing Pt with non-precious metal catalysts (NPMCs) synthesized from earth abundant elements (C, N, Fe, etc.) is therefore essential to deploy PEFCs for transportation applications. Recently, many advances have been realized towards the development of NPMCs. One of the most important advances is the synthesis of highly porous (HP)-NPMCs. HP-NPMCs allow for improved active site accessibility as well as facilitated mass transport. This is especially important as the relatively low volumetric activity of NPMCs leads to a significantly larger electrode thickness for NPMCs in comparison to Pt/C catalysts, i.e., ca. 70 μm vs. 10 μm, respectively. Two main strategies that have been employed to achieve HP-NPMCs are the use of: (i) metal-organic frameworks (MOFs) [1] and (ii) template agents such as silica [2]. MOFs however are generally very expensive, with only very few commercially available, and a silica template approach requires using highly corrosive and hazardous reagents such as hydrofluoric acid for a silica template removal. These approaches are therefore far from ideal for efficient catalyst production. In this work, we adopted a more proficient technique that uses combined nitrogen precursors. With this method, a lower decomposition temperature nitrogen precursor, cyanamide (CM), and higher decomposition temperature nitrogen precursor, polyanniline (PANI), are concurrently used. Under this circumstance, during heat-treatment, CM works as an efficient foaming agent. Indeed, we can synthesize HP-NPMCs with a microporous surface area of 1585 m2/g, and demonstrate record H2-air fuel cell performance (Fig. 1). In this talk, more detailed microscopic features and electrochemical and fuel cell performances of these HP-MPMCs will be presented. Acknowledgements Financial support for this has been provided by the DOE-EERE through the Fuel Cells Technologies Office. References Proietti et al., Nat. Commun. 2, 416 (2011).Serov et al., Appl. Catal. B: Environmental, 127, 300 (2012). Figure 1

Transcap: A New Integrated Hybrid Supercapacitor and Electrolyte-Gated Transistor Device

The recent boom in multifunction, light and flexible portable electronic equipment and the increasing need of low-energy cost and autonomy for different fields ranging from wireless sensor networks for smart environments to biomedical applications are triggering intensive research efforts towards the development of self-powered, sustainable electronic devices. Within this context, the coupling of electronic devices (sensors,transistors, etc.) with small size energy storage systems (e.g. micro-batteries or micro-supercapacitors) is actively pursued. Micro-electrochemical supercapacitors are attracting much attention in electronics for their capability of delivering short power pulses with high stability over repeated charge/discharge cycling. One of the strategy which is pursued to increase the energy storage capability of supercapacitor is coupling electrode materials of different nature that are charged/discharged via different electrostatic and faradic modes in a hybrid configuration. The use of wide electrochemically stability electrolytes like ionic liquids, permits to achieve high cell voltage and , hence high energy. For their high specific pseudocapacitance, electronically conducting polymers are well known as positive materials for hybrid supercapacitors featuring high surface carbon negative electrodes. The processability of both polymer and carbon is of great relevance for the development of flexible miniaturised devices. Electronically conducting polymers are even well known to feature an electronic conductivity that depends on their oxidation (p-doped state) and that it is modulated by the polymer potential. This property and the related pseudocapacitive response make polymer very attracting channel materials for electrolyte-gated (EG) transistors. In this systems electrolytes replace conventional gate dielectrics and permit low-voltage operation, which in turn makes EG transistors attractive candidates to be coupled to energy harvester/storage microsystems. Here, we propose a novel concept of “Trans-capacitor”, an integrated device that exhibits the storage properties of a polymer/carbon hybrid supercapacitor and the low-voltage operation of an electrolyte-gated transistor. When the TransCap is ON, the polymer transistor channel is open. The p-doped polymer and the negatively polarized carbon gate electrode are storing the charge at a given gate-source voltage, hence the system is storing energy. When the TransCap is switched OFF, the channel and the gate are discharged and the delivered energy can be used for subsequent operation of the EG transistor itself or to power other components in the electronic system. This multifunctionality should positively impact on energy saving in the multicomponent electronic system where the TransCap will be used [1]. The performance of a TransCap based on a polymer channel like MEH-PPV, poly[2-methoxy-5-(20-ethylhexyloxy)-1,4-phenylene vinylene], a high surface area carbon gate, and the ionic liquid N-trimethyl-N-propylammonium bis (trifuoromethanesulfonyl) imide electrolyte are here reported and discussed. ACKNOWLEDGEMENTS This work was financially supported by NSERC (Discovery grants, CS and FC) and FQRNT (Nouveau Chercheur, CS). JS acknowledges fiancial support by CONACYT and CMC Microsystems. FS acknowledges financial support by Università di Bologna (Researcher Mobility Program, Italian-Canadian cooperation agreement). [1] J. Sayago, U. Shafique, F. Soavi, F. Cicoira and C. Santato, J. Mater. Chem. C, DOI: 10.1039/c4tc02119c

Combined Nitrogen Precursor Approach to Develop Cobalt-Based Non-Precious Catalysts for Polymer Electrolyte Fuel Cell Cathodes

The cost of the platinum-based catalysts used in polymer electrolyte membrane fuel cells (PEFCs) is estimated to be almost half of the overall fuel cell stack cost under projected conditions of fuel cell vehicle mass production [1]. To reduce this economic constraint, the development of non-platinum group metal (non-PGM) cathode catalysts with high oxygen reduction reaction (ORR) activity is highly desirable. Our group and others have demonstrated immense progress in non-PGM catalyst development, with the specific class of pyrolyzed transition metal-nitrogen-carbon (M-N-C) catalysts achieving high activity [2,3]. In order to realize the successful implementation of these non-PGM catalysts into PEFC systems, the significant issue of operational durability must be addressed. The two most promising M-N-C catalyst technologies are based on either iron or cobalt, with the former conventionally providing enhanced ORR performance, approaching that of commercial platinum catalysts. From a system perspective, however, the presence of iron species in the catalyst layer is highly undesirable. This is owing to the well-known Fenton chemistry, resulting in the formation of highly reactive free-radical species that in turn leads to membrane and/or ionomer decomposition. To address this challenge, we prepared cobalt-based catalysts using the combined-precursor approach recently developed at Los Alamos National Laboratory [4]. This approach utilizes both polyacrylonitrile (PANI) and cyanamide (CM) as nitrogen/carbon precursors that are combined and pyrolyzed with a carbon support and cobalt salt. Individually, both PANI and CM precursors have been previously demonstrated capable of forming highly ORR-active catalysts. Through this approach, we found that the relatively low decomposition temperature (ca. 260°C) of CM allows it to synergistically act as a pore-forming agent and yield high surface-area catalysts. This in turn leads to excellent H2-air fuel cell performance due to the reduced mass transport limitations in the cathode. In this work, Co-CM-PANI-C was formed and found to provide promising activity towards the ORR in acidic electrolyte. Particularly, it was determined that 8.0 wt.% cobalt in the precursor mixture provided optimal ORR activity through half-cell investigation (Figure 1). A half-wave potential of ca. 0.74 V vs.RHE was achieved, with current investigations underway to understand and optimize the structure-performance-durability relationships. These results, along with performance and durability data from both half-cell and MEA evaluation, will be presented at the meeting. Acknowledgements Financial support for this was has been provided by the DOE-EERE through the Fuel Cells Technologies Office and by the Natural Sciences and Engineering Research Council of Canada (NSERC).

Latitudinal variation of migratory life histories of riverine Galaxias maculatus in Chile (36°- 47°S)

Event Abstract Back to Event Latitudinal variation of migratory life histories of riverine Galaxias maculatus in Chile (36°- 47°S) Konrad Górski1, 2*, Evelyn M. Habit2 and Aliro J. Manosalva2 1 Universidad Católica de la Santísima Concepción, Departamento de Ecología, Chile 2 Universidad de Concepción, Facultad de Ciencias Ambientales, Chile A relationship between life histories and increasing latitude has been described for Northern Hemisphere riverine fish, whereby life cycles that complete most of the growth in the ocean are favoured at higher latitudes. In the riverine ecosystems of the Southern Hemisphere many species of galaxiids display highly flexible migratory life histories and the mechanisms driving employment of different strategies remain unclear. Our objective was to assess the mechanisms driving the selection of migratory strategies of Galaxias maculatus from rivers across a gradient of latitude. Fifteen fish from three size classes as well as water samples were collected from upper, middle and lower sections of 10 river systems in Chile across latitudes 36°- 47°S. Otoliths and water samples were analysed for a suite of trace elements using Laser Ablation Inductively Coupled Plasma Mass Spectrometry. Otolith elemental composition was analysed through depth profiling to assess the frequency of marine migrations in each section of each river. The propensity of marine migrations was strongly related to latitude as well as flow and temperature dynamics of each river system. Fish in river systems at higher latitudes more frequently displayed use of marine and brackish habitats, potentially enabling them to maximise foraging opportunities and increase recruitment success. River systems originating from large Andean lakes with more predictable flow pattern (large scale spring floodplain inundations and therefore more predictable food supplies) accommodated more resident individuals with no marine signatures even at higher latitudes. Therefore, climate as well as both longitudinal (headwaters-estuary) and lateral (main channel-floodplains) hydrologic connectivity seem to govern migratory strategies of riverine Galaxias maculatus. Consequently, management strategies that promote both lateral and longitudinal connectivity within riverine ecosystems are crucial to maximise habitat availability for this native fish species. Acknowledgements Financial support: Fondecyt 3130690, DIUC 213.310.063-1AP Keywords: Fish migration, Diadromy, LA-ICP-MS, Otolith microchemistry, Puye, īnanga Conference: XV European Congress of Ichthyology, Porto, Portugal, 7 Sep - 11 Sep, 2015. Presentation Type: Oral Presentation Topic: Otoliths as a tool to study fish life cycles Citation: Górski K, Habit EM and Manosalva AJ (2015). Latitudinal variation of migratory life histories of riverine Galaxias maculatus in Chile (36°- 47°S). Front. Mar. Sci. Conference Abstract: XV European Congress of Ichthyology. doi: 10.3389/conf.fmars.2015.03.00031 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 23 Oct 2015; Published Online: 04 Nov 2015. * Correspondence: Dr. Konrad Górski, Universidad Católica de la Santísima Concepción, Departamento de Ecología, Concepción, Chile, konrad.gorski@uach.cl Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Konrad Górski Evelyn M Habit Aliro J Manosalva Google Konrad Górski Evelyn M Habit Aliro J Manosalva Google Scholar Konrad Górski Evelyn M Habit Aliro J Manosalva PubMed Konrad Górski Evelyn M Habit Aliro J Manosalva Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Inferring phylogenetic structure and ancient hybridization within Salmonidae using next-generation sequencing

Event Abstract Back to Event Inferring phylogenetic structure and ancient hybridization within Salmonidae using next-generation sequencing Laurène A. Lecaudey1*, Steven J. Weiss1 and Ulrich K. Schliewen2 1 University of Graz, Institute of Zoology, Austria 2 Bavarian State Collection of Zoology, Department of Ichthyology, Germany Phylogenetic studies focusing on Salmonidae have thus far revealed significant drawbacks to elucidate some of the interspecific relationships within the family, due to limited number of markers, conflicting phylogenetic signals and hybridization events. In an attempt to resolve these issues, we applied restriction-site associated DNA sequencing (RAD-seq) to 44 samples, including 23 different species across the family Salmonidae, with an emphasis on the genus Salvelinus. The aim of our study is to infer reliable interspecific phylogenetic relationships, evaluate several putative scenarios of ancient hybridization and detect possible reticulate patterns of evolution among salmonid fishes. RAD-seq can be particularly useful for systematic studies of closely related taxa, as it provides genome-wide informative characters and allows the detection of introgression. To our knowledge, this is the first next generation sequencing effort applied to salmonid phylogeny and related questions of their evolutionary history. Using the software pipeline pyRAD, we identified 28,402 orthologous loci, which were subsequently used in our downstream analyses. Phylogenetic inferences drawn from a maximum likelihood analysis reveal some interesting results. Salvelinus and Oncorhynchus appear as sister lineages, which contradicts some of the previous phylogenetic analyses. Additionally, despite constituting a separate genus, Salvethymus clusters within the genus Salvelinus, which is consistent with the findings of previous studies and therefore questions its taxonomic status. A monophylum of Salvelinus leucomaenis and Salvelinus levanidovi is the sister group to the remainder of the genus Salvelinus. The genus Parahucho appears as the sister clade to Salmo, which also contradicts some previously published inferences. Finally, we present a practical application of a relatively novel approach to test for putative ancient hybridization events. Since this is the first Salmonidae phylogeny based on RAD-seq data, our findings represent a valuable contribution to the systematics of this important family of freshwater fishes. Our results provide a better understanding of the mechanisms of speciation and ecological adaptation of Salmonidae, as well as the effect of hybridization on speciation, within an evolutionary framework. Acknowledgements Financial support was provided by the Austrian Center for Limnology (ACL) at the University of Graz. Keywords: RAD-seq, NGS, Salmo, Salvelinus, Parahucho, pyRAD, Introgression Conference: XV European Congress of Ichthyology, Porto, Portugal, 7 Sep - 11 Sep, 2015. Presentation Type: Oral Presentation Topic: Phylogeny, Systematics and Genetics Citation: Lecaudey LA, Weiss SJ and Schliewen UK (2015). Inferring phylogenetic structure and ancient hybridization within Salmonidae using next-generation sequencing. Front. Mar. Sci. Conference Abstract: XV European Congress of Ichthyology. doi: 10.3389/conf.fmars.2015.03.00008 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 30 Oct 2015; Published Online: 04 Nov 2015. * Correspondence: Ms. Laurène A Lecaudey, University of Graz, Institute of Zoology, Graz, 8010, Austria, laurenelecaudey@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Laurène A Lecaudey Steven J Weiss Ulrich K Schliewen Google Laurène A Lecaudey Steven J Weiss Ulrich K Schliewen Google Scholar Laurène A Lecaudey Steven J Weiss Ulrich K Schliewen PubMed Laurène A Lecaudey Steven J Weiss Ulrich K Schliewen Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Microparticles forming immune complexes in Rheumatoid Arthritis patients could be associated with the altered phenotype of classical and intermediate monocyte subsets

Microparticles forming immune complexes in Rheumatoid Arthritis patients could be associated with the altered phenotype of classical and intermediate monocyte subsets

The dynamical response properties of cortical neurons

Event Abstract Back to Event The dynamical response properties of cortical neurons Daniele Linaro1, Istvan Biro1 and Michele Giugliano1* 1 Universiteit Antwerpen, Department of Biomedical Sciences, Belgium Cortical neurons are often classified by current-frequency relationship. Such a static description is inadequate to interpret neuronal responses to time-varying stimuli. Theoretical studies suggested that single-cell dynamical response properties are necessary to interpret ensemble responses to fast input transients. Further, it was shown that input-noise linearizes and boosts the response bandwidth, and that the interplay between the barrage of noisy synaptic currents and the spike-initiation mechanisms determine the dynamical properties of the firing rate. To test these model predictions, we estimated the linear response properties of layer 5 pyramidal cells by injecting a superposition of a small-amplitude sinusoidal wave and a background noise. We characterized the evoked firing probability across many stimulation trials and a range of oscillation frequencies (1-1000 Hz), quantifying response amplitude and phase-shift while changing noise statistics. We found that neurons track unexpectedly fast transients, as their response amplitude has no attenuation up to 200 Hz. This cut-off frequency is higher than the limits set by passive membrane properties (approximately 50 Hz) and average firing rate (approximately 20 Hz) and is not affected by the rate of change of the input. Finally, above 200 Hz, the response amplitude decays as a power-law with an exponent that is independent of voltage fluctuations induced by the background noise. Acknowledgements Financial support from the University of Antwerp, the Flanders Research Foundation (12C9112N), and the European Commission (FP7-FETOPEN project "BRAINLEAP", contract m. 306502) is kindly acknowledged. References Köndgen, H., Geisler, C., Fusi, S. , Lüscher, H.-R. , Wang, X.J. and Giugliano, M. (2008) The dynamical response properties of neocortical neurons to temporally modulated noisy inputs in vitro. Cerebral Cortex 18(9):2086-97. Linaro D, Couto J, Giugliano M (2014) Command-line cellular electrophysiology for conventional and real-time closed-loop experiments. J Neurosci Methods. 2014 Jun 15;230:5-19. doi: 10.1016/j.jneumeth.2014.04.003. Robinson HPC, (2009), “Synaptic conductances and spike generation in cortical cells.” In: Dynamic clamp: from Principles to Applications, Springer. Testa-Silva G, Verhoog MB, Linaro D, de Kock CP, Baayen JC, Meredith RM, De Zeeuw CI, Giugliano M, Mansvelder HD (2014) High bandwidth synaptic communication and frequency tracking in human neocortex. PLoS Biol. 2014 Nov 25;12(11):e1002007. doi: 10.1371/journal.pbio.1002007. Keywords: dynamic-clamp, human cortical neurons, correlations, Noise, action potential initation Conference: Spike Initiation: Models & Experiments, Prague, Czechia, 22 Jul - 22 Jul, 2015. Presentation Type: Oral Presentation Topic: Neuroscience Citation: Linaro D, Biro I and Giugliano M (2015). The dynamical response properties of cortical neurons. Front. Neurosci. Conference Abstract: Spike Initiation: Models & Experiments. doi: 10.3389/conf.fnins.2015.90.00002 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 30 Jun 2015; Published Online: 06 Jul 2015. * Correspondence: Prof. Michele Giugliano, Universiteit Antwerpen, Department of Biomedical Sciences, Wilrijk, Flanders, 2610, Belgium, michele.giugliano@sissa.it Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Daniele Linaro Istvan Biro Michele Giugliano Google Daniele Linaro Istvan Biro Michele Giugliano Google Scholar Daniele Linaro Istvan Biro Michele Giugliano PubMed Daniele Linaro Istvan Biro Michele Giugliano Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

QUANTIFICATION AND PHENOTYPIC CHARACTERIZATION OF MONOCYTES SUBSETS IN HUMAN ATHEROSCLEROSIS

QUANTIFICATION AND PHENOTYPIC CHARACTERIZATION OF MONOCYTES SUBSETS IN HUMAN ATHEROSCLEROSIS

Analysis and effect of high intensity interval training program on monocytes subsets in obese individuals

Analysis and effect of high intensity interval training program on monocytes subsets in obese individuals

Study of Cell Migration in Intraperitoneal Infection by Escherichia coli in Mice Swiss

Study of Cell Migration in Intraperitoneal Infection by Escherichia coli in Mice Swiss

Clinical and Immunological Characterization of Patients with Selective IgA Deficiency (SIgAD) in Colombia.

Clinical and Immunological Characterization of Patients with Selective IgA Deficiency (SIgAD) in Colombia.