Proton permeation of lipid bilayers.

PubMed

Deamer, D W

1987-10-01

Proton permeation of the lipid bilayer barrier has two unique features. First, permeability coefficients measured at neutral pH ranges are six to seven orders of magnitude greater than expected from knowledge of other monovalent cations. Second, proton conductance across planar lipid bilayers varies at most by a factor of 10 when pH is varied from near 1 to near 11. Two mechanisms have been proposed to account for this anomalous behavior: proton conductance related to contaminants of lipid bilayers, and proton translocation along transient hydrogen-bonded chains (tHBC) of associated water molecules in the membrane. The weight of evidence suggests that trace contaminants may contribute to proton conductance across planar lipid membranes at certain pH ranges, but cannot account for the anomalous proton flux in liposome systems. Two new results will be reported here which were designed to test the tHBC model. These include measurements of relative proton/potassium permeability in the gramicidin channel, and plots of proton flux against the magnitude of pH gradients. (1) The relative permeabilities of protons and potassium through the gramicidin channel, which contains a single strand of hydrogen-bonded water molecules, were found to differ by at least four orders of magnitude when measured at neutral pH ranges. This result demonstrates that a hydrogen-bonded chain of water molecules can provide substantial discrimination between protons and other cations. It was also possible to calculate that if approximately 7% of bilayer water was present in a transient configuration similar to that of the gramicidin channel, it could account for the measured proton flux. (2) The plot of proton conductance against pH gradient across liposome membranes was superlinear, a result that is consistent with one of three alternative tHBC models for proton conductance described by Nagle elsewhere in this volume.

Rectified Proton Grotthuss Conduction Across a Long Water-Wire in the Test Nanotube of the Polytheonamide B Channel.

PubMed

Matsuki, Yuka; Iwamoto, Masayuki; Mita, Kenichiro; Shigemi, Kenji; Matsunaga, Shigeki; Oiki, Shigetoshi

2016-03-30

A hydrogen-bonded water-chain in a nanotube is highly proton conductive, and examining the proton flux under electric fields is crucial to understanding the one-dimensional Grotthuss conduction. Here, we exploited a nanotube-forming natural product, the peptide polytheonamide B (pTB), to examine proton conduction mechanisms at a single-molecule level. The pTB nanotube has a length of ∼40 Å that spans the membrane and a uniform inner diameter of 4 Å that holds a single-file water-chain. Single-channel proton currents were measured using planar lipid bilayers in various proton concentrations and membrane potentials (±400 mV). We found, surprisingly, that the current-voltage curves were asymmetric with symmetric proton concentrations in both solutions across the membrane (rectification). The proton flux from the C-terminal to the N-terminal end was 1.6 times higher than that from the opposite. At lower proton concentrations, the degree of rectification was attenuated, but with the addition of a pH-buffer (dichloroacetate) that supplies protons near the entrance, the rectification emerged. These results indicate that the permeation processes inside the pore generate the rectification, which is masked at low concentrations by the diffusion-limited access of protons to the pore entrance. The permeation processes were characterized by a discrete-state Markov model, in which hops of a proton followed by water-chain turnovers were implemented. The optimized model revealed that the water-chain turnover exhibited unusual voltage dependence, and the distinct voltage-dependencies of the forward and backward transition rates yielded the rectification. The pTB nanotube serves as a rectified proton conductor, and the design principles can be exploited for proton-conducting materials.

Superoxide activates a GDP-sensitive proton conductance in skeletal muscle mitochondria from king penguin (Aptenodytes patagonicus).

PubMed

Talbot, Darren A; Hanuise, Nicolas; Rey, Benjamin; Rouanet, Jean-Louis; Duchamp, Claude; Brand, Martin D

2003-12-26

We present the partial nucleotide sequence of the avian uncoupling protein (avUCP) gene from king penguin (Aptenodytes patagonicus), showing that the protein is 88-92% identical to chicken (Gallus gallus), turkey (Meleagris gallopavo), and hummingbird (Eupetomena macroura). We show that superoxide activates the proton conductance of mitochondria isolated from king penguin skeletal muscle. GDP abolishes the superoxide-activated proton conductance, indicating that it is mediated via avUCP. In the absence of superoxide there is no GDP-sensitive component of the proton conductance from penguin muscle mitochondria demonstrating that avUCP plays no role in the basal proton leak.

Proton conducting membrane using a solid acid

NASA Technical Reports Server (NTRS)

Boysen, Dane A. (Inventor); Narayanan, Sekharipuram R. (Inventor); Haile, Sossina M. (Inventor); Chisholm, Calum (Inventor)

2006-01-01

A solid acid material is used as a proton conducting membrane in an electrochemical device. The solid acid material can be one of a plurality of different kinds of materials. A binder can be added, and that binder can be either a nonconducting or a conducting binder. Nonconducting binders can be, for example, a polymer or a glass. A conducting binder enables the device to be both proton conducting and electron conducting.

Proton dynamics in oxides: insight into the mechanics of proton conduction from quasielastic neutron scattering.

PubMed

Karlsson, Maths

2015-01-07

This article is concerned with the use of quasielastic neutron scattering as a technique for investigation of the dynamical properties of proton conducting oxides. Currently, the main interest in these materials comes from their promise as electrolytes in future electrochemical devices and particularly through their use as electrolytes in next-generation, intermediate-temperature, fuel cells. However, the realization of such devices depends critically on the development of new, more highly proton conducting oxides. Such a development depends on increasing the current understanding of proton conduction in oxides and for this purpose quasielastic neutron scattering is an important mean. The aim of this article is to introduce the non-specialist reader to the basic principles of quasielastic neutron scattering, its advantages and disadvantages, to summarize the work that has been done on proton conducting oxides using this technique, as well as to discuss future opportunities within this field of research.

Intermediate temperature proton conductors for PEM fuel cells based on phosphonic acid as protogenic group: a progress report.

PubMed

Steininger, H; Schuster, M; Kreuer, K D; Kaltbeitzel, A; Bingöl, B; Meyer, W H; Schauff, S; Brunklaus, G; Maier, J; Spiess, H W

2007-04-21

The melting behaviour and transport properties of straight chain alkanes mono- and difunctionalized with phosphonic acid groups have been investigated as a function of their length. The increase of melting temperature and decrease of proton conductivity with increasing chain length is suggested to be the consequence of an increasing ordering of the alkane segments which constrains the free aggregation of the phosphonic acid groups. However, the proton mobility is reduced to a greater extent than the proton diffusion coefficient indicating an increasing cooperativity of proton transport with increasing length of the alkane segment. The results clearly indicate that the "spacer concept", which had been proven successful in the optimization of the proton conductivity of heterocycle based systems, fails in the case of phosphonic acid functionalized polymers. Instead, a very high concentration of phosphonic acid functional groups forming "bulky" hydrogen bonded aggregates is suggested to be essential for obtaining very high proton conductivity. Aggregation is also suggested to reduce condensation reactions generally observed in phosphonic acid containing systems. On the basis of this understanding, the proton conductivities of poly(vinyl phosphonic acid) and poly(meta-phenylene phosphonic acid) are discussed. Though both polymers exhibit a substantial concentration of phosphonic acid groups, aggregation seems to be constrained to such an extent that intrinsic proton conductivity is limited to values below sigma = 10(-3) S cm(-1) at T = 150 degrees C. The results suggest that different immobilization concepts have to be developed in order to minimize the conductivity reduction compared to the very high intrinsic proton conductivity of neat phosphonic acid under quasi dry conditions. In the presence of high water activities, however, (as usually present in PEM fuel cells) the very high ion exchange capacities (IEC) possible for phosphonic acid functionalized ionomers (IEC >10 meq g(-1)) may allow for high proton conductivities in the intermediate temperature range (T approximately 120 -160 degrees C).

Proton conductivity and methanol permeability of Nafion-SiO2/SiWA composite membranes

NASA Astrophysics Data System (ADS)

Thiam, Hui San; Chia, Min Yan; Cheah, Qiao Rou; Koo, Charlene Chai Hoon; Lai, Soon Onn; Chong, Kok Chung

2017-04-01

Proton exchange membranes for a direct methanol fuel cell (DMFC) were prepared by incorporating silica/silicotungstic acid (SiO2/SiWA) inorganic composite into a Nafion polymer. The effects of SiO2/SiWA content on proton conductivity of membranes were investigated by using a four-probe conductivity cell. Methanol permeability of composite membrane was also determined by using a homemade diffusion cell and gas chromatography technique. It was found that proton conductivity of the composite membranes decreased with SiO2/SiWA content, however the highest proton conductivity achieved was 11% greater than the pure recast Nafion membrane. The methanol permeability of composite membrane was much lower than that of pure recast Nafion, in a reduction of 58% which indicated a better resistance to fuel crossover. Nafion-SiO2/SiWA composite membrane showed promising advantages over pure Nafion on electrochemical properties such as proton conductivity and fuel crossover and it is potentially attractive for use in DMFC.

Cationic Covalent Organic Frameworks: A Simple Platform of Anionic Exchange for Porosity Tuning and Proton Conduction.

PubMed

Ma, Heping; Liu, Bailing; Li, Bin; Zhang, Liming; Li, Yang-Guang; Tan, Hua-Qiao; Zang, Hong-Ying; Zhu, Guangshan

2016-05-11

Mimicking proton conduction mechanism of Nafion to construct novel proton-conducting materials with low cost and high proton conductivity is of wide interest. Herein, we have designed and synthesized a cationic covalent organic framework with high thermal and chemical stability by combining a cationic monomer, ethidium bromide (EB) (3,8-diamino-5-ethyl-6-phenylphenanthridinium bromide), with 1,3,5-triformylphloroglucinol (TFP) in Schiff base reactions. This is the first time that the stable cationic crystalline frameworks allowed for the fabrication of a series of charged COFs (EB-COF:X, X = F, Cl, Br, I) through ion exchange processes. Exchange of the extra framework ions can finely modulate the COFs' porosity and pore sizes at nanoscale. More importantly, by introducing PW12O40(3-) into this porous cationic framework, we can greatly enhance the proton conductivity of ionic COF-based material. To the best of our knowledge, EB-COF:PW12 shows the best proton conductivity at room temperature among ever reported porous organic materials.

1000-fold enhancement in proton conductivity of a MOF using post-synthetically anchored proton transporters

PubMed Central

Shalini, Sorout; Dhavale, Vishal M.; Eldho, Kavalakal M.; Kurungot, Sreekumar; Ajithkumar, Thallaseril G.; Vaidhyanathan, Ramanathan

2016-01-01

Pyridinol, a coordinating zwitter-ionic species serves as stoichiometrically loadable and non-leachable proton carrier. The partial replacement of the pyridinol by stronger hydrogen bonding, coordinating guest, ethylene glycol (EG), offers 1000-fold enhancement in conductivity (10−6 to 10−3 Scm−1) with record low activation energy (0.11 eV). Atomic modeling coupled with 13C-SSNMR provides insights into the potential proton conduction pathway functionalized with post-synthetically anchored dynamic proton transporting EG moieties. PMID:27577681

Increasing the proton conductivity of sulfonated polyether ether ketone by incorporating graphene oxide: Morphology effect on proton dynamics

NASA Astrophysics Data System (ADS)

Leong, Jun Xing; Diño, Wilson Agerico; Ahmad, Azizan; Daud, Wan Ramli Wan; Kasai, Hideaki

2018-03-01

We synthesized graphene oxide-sulfonated polyether ether ketone (GO-SPEEK) composite membrane and compare its proton conductivity with that of Nafion® 117 and SPEEK membranes. From experimental measurements, we found that GO-SPEEK has better proton conductivity (σGO-SPEEK = 3.8 × 10-2 S cm-1) when compared to Nafion® 117 (σNafion = 2.4 × 10-2 S cm-1) and SPEEK (σSPEEK = 2.9 × 10-3 S cm-1). From density functional theory (DFT-) based total energy calculations, we found that GO-SPEEK has the shortest proton diffusion distance among the three membranes, yielding the highest tunneling probability. Hence, GO-SPEEK exhibits the highest conductivity. The short proton diffusion distance in GO-SPEEK, as compared to Nafion® 117 and SPEEK, can be attributed to the presence of oxygenated functional groups of GO in the polymer matrix. This also explains why GO-SPEEK requires the lowest hydration level to reach its maximum conductivity. Moreover, we have successfully shown that the proton conductivity σ is related to the tunneling probability T, i.e., σ = σ‧ exp(-1/T). We conclude that the proton diffusion distance and hydration level are the two most significant factors that determine the membrane’s good conductivity. The distance between ionic sites of the membrane should be small to obtain good conductivity. With this short distance, lower hydration level is required. Thus, a membrane with short separation between the ionic sites can have enhanced conductivity, even at low hydration conditions.

Crystalline polyoxometalate (POM)–polyethylene glycol (PEG) composites aimed as non-humidified intermediate-temperature proton conductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsuboi, Masaki; Hibino, Mitsuhiro; Mizuno, Noritaka

2016-02-15

Crystalline polyoxometalate (POM)–polyethylene glycol (PEG) composites aimed as non-humidified intermediate-temperature proton conductors were synthesized and characterized by single crystal and powder XRD, solid state MASNMR, and TG-DTA measurements. Among the POM–PEG composites, Cs{sub 2.7}H{sub 0.3}[PW{sub 12}O{sub 40}]·1.2PEG1000 (CsHPW-PEG1000) possessed one-dimensional channels with diameters of ca. 6 and 8 Å, where PEG probably resided, and showed the best performance as a proton conductor (1.2×10{sup −5} S cm{sup −1} at 443 K). Proton conductivities of POM–PEG composites decreased by the increase in molecular weights of PEG (CsHPW-PEG12,000) or anion charges (CsHSiW-PEG1000). Variable contact time {sup 13}C-CP (cross polarization) MASNMR revealed that localmore » mobility (i.e., segmental motion) of PEG is related to the trends in proton conductivities. These results show that amount of acidic protons (H{sup +}) is not the primary factor in proton conduction and that segmental motion of PEG assists the proton hopping among POMs in the crystal lattice of POM–PEG composites. - Graphical abstract: Non-humidified intermediate-temperature proton conduction in crystalline polyoxometalate (POM)–polyethylene (PEG) composites are assisted by the segmental motion of PEG. - Highlights: • Crystalline polyoxometalate–polyethlene glycol (PEG) composites were synthesized. • CsHPW-PEG1000 possessed one-dimensional channels and showed the highest proton conductivity. • {sup 13}C CPMASNMR revealed that segmental motion of PEG is related to the proton conduction.« less

Unique Proton Transportation Pathway in a Robust Inorganic Coordination Polymer Leading to Intrinsically High and Sustainable Anhydrous Proton Conductivity.

PubMed

Gui, Daxiang; Dai, Xing; Tao, Zetian; Zheng, Tao; Wang, Xiangxiang; Silver, Mark A; Shu, Jie; Chen, Lanhua; Wang, Yanlong; Zhang, Tiantian; Xie, Jian; Zou, Lin; Xia, Yuanhua; Zhang, Jujia; Zhang, Jin; Zhao, Ling; Diwu, Juan; Zhou, Ruhong; Chai, Zhifang; Wang, Shuao

2018-05-16

Although comprehensive progress has been made in the area of coordination polymer (CP)/metal-organic framework (MOF)-based proton-conducting materials over the past decade, searching for a CP/MOF with stable, intrinsic, high anhydrous proton conductivity that can be directly used as a practical electrolyte in an intermediate-temperature proton-exchange membrane fuel cell assembly for durable power generation remains a substantial challenge. Here, we introduce a new proton-conducting CP, (NH 4 ) 3 [Zr(H 2/3 PO 4 ) 3 ] (ZrP), which consists of one-dimensional zirconium phosphate anionic chains and fully ordered charge-balancing NH 4 + cations. X-ray crystallography, neutron powder diffraction, and variable-temperature solid-state NMR spectroscopy suggest that protons are disordered within an inherent hydrogen-bonded infinite chain of acid-base pairs (N-H···O-P), leading to a stable anhydrous proton conductivity of 1.45 × 10 -3 S·cm -1 at 180 °C, one of the highest values among reported intermediate-temperature proton-conducting materials. First-principles and quantum molecular dynamics simulations were used to directly visualize the unique proton transport pathway involving very efficient proton exchange between NH 4 + and phosphate pairs, which is distinct from the common guest encapsulation/dehydration/superprotonic transition mechanisms. ZrP as the electrolyte was further assembled into a H 2 /O 2 fuel cell, which showed a record-high electrical power density of 12 mW·cm -2 at 180 °C among reported cells assembled from crystalline solid electrolytes, as well as a direct methanol fuel cell for the first time to demonstrate real applications. These cells were tested for over 15 h without notable power loss.

Tuning Proton Conductivity by Interstitial Guest Change in Size-Adjustable Nanopores of a CuI -MOF: A Potential Platform for Versatile Proton Carriers.

PubMed

Khatua, Sajal; Kumar Bar, Arun; Konar, Sanjit

2016-11-02

By exploiting the breathing behavior of nanopores, we have studied for the first time the dependency of the guest-induced proton conductivity of an interpenetrated Cu I metal-organic framework (Cu I -MOF, [1]) on various guest molecules. Proton conductivities of over 10 -3  S cm -1 under humid conditions were induced by a series of guest molecules, namely N,N-dimethylformamide, dimethyl sulfoxide, diethylamine, 1,4-dinitrobenzene, nitrobenzene, pyridine, and 1H-1,2,4-triazole. A detailed investigation of the guest-incorporated complexes revealed that low-energy proton conduction occurs under humid conditions through the Grotthuss mechanism in [1⊃NB] and through the vehicle mechanism in the rest of the complexes. Single-point energy computations revealed considerable stabilization upon guest encapsulation. To the best of our knowledge, [1] represents the first example in which considerably high protonic conductivity is triggered upon the facile incorporation of small molecules of such a variety. The investigation portrayed herein may be a stepping stone towards the rational design of proton-conducting materials for practical applications. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Role of Water in Proton-Hydroxide Conductance Across Model and Biological Membranes

DTIC Science & Technology

1989-09-30

of water in proton-hydroxide conductance across model and biological membranes 12. PERSONAL AUTHOR(S) Deamer, David W. 1 a. TYPE OF REPORT 13b. TIME...identify by block number) The goal of this research is to understand the mechanism of proton translocation in model and biological membranes. The...which conducts protons through hydrogen bonded water, thereby providing an important model for investigating such processes. The Fo subunit of

Correlation between coordinated water content and proton conductivity in Ca-BTC-based metal-organic frameworks.

PubMed

Mallick, Arijit; Kundu, Tanay; Banerjee, Rahul

2012-09-11

Proton conductivity of five Ca-based MOFs which depends on the amount of water molecules coordinated to the Ca-centres has been reported. These MOFs show high temperature proton conductivity due to the strong hydrogen bonding between the lattice and coordinated water molecules.

Anhydrous Proton-Conducting Membranes for Fuel Cells

NASA Technical Reports Server (NTRS)

Narayanan, Sekharipuram; Yen, Shiao-Pin S.

2005-01-01

Polymeric electrolyte membranes that do not depend on water for conduction of protons are undergoing development for use in fuel cells. Prior polymeric electrolyte fuel-cell membranes (e.g., those that contain perfluorosulfonic acid) depend on water and must be limited to operation below a temperature of 125 C because they retain water poorly at higher temperatures. In contrast, the present developmental anhydrous membranes are expected to function well at temperatures up to 200 C. The developmental membranes exploit a hopping-and-reorganization proton- conduction process that can occur in the solid state in organic amine salts and is similar to a proton-conduction process in a liquid. This process was studied during the 1970s, but until now, there has been no report of exploiting organic amine salts for proton conduction in fuel cells.

Preparations of an inorganic-framework proton exchange nanochannel membrane

NASA Astrophysics Data System (ADS)

Yan, X. H.; Jiang, H. R.; Zhao, G.; Zeng, L.; Zhao, T. S.

2016-09-01

In this work, a proton exchange membrane composed of straight and aligned proton conducting nanochannels is developed. Preparation of the membrane involves the surface sol-gel method assisted with a through-hole anodic aluminum oxide (AAO) template to form the framework of the PEM nanochannels. A monomolecular layer (SO3Hsbnd (CH2)3sbnd Sisbnd (OCH3)3) is subsequently added onto the inner surfaces of the nanochannels to shape a proton-conducting pathway. Straight nanochannels exhibit long range order morphology, contributing to a substantial improvement in the proton mobility and subsequently proton conductivity. In addition, the nanochannel size can be altered by changing the surface sol-gel condition, allowing control of the active species/charge carrier selectivity via pore size exclusion. The proton conductivity of the nanochannel membrane is reported as high as 11.3 mS cm-1 at 70 °C with a low activation energy of 0.21 eV (20.4 kJ mol-1). First-principle calculations reveal that the activation energy for proton transfer is impressively low (0.06 eV and 0.07 eV) with the assistance of water molecules.

Gate modulation of proton transport in a nanopore.

PubMed

Mei, Lanju; Yeh, Li-Hsien; Qian, Shizhi

2016-03-14

Proton transport in confined spaces plays a crucial role in many biological processes as well as in modern technological applications, such as fuel cells. To achieve active control of proton conductance, we investigate for the first time the gate modulation of proton transport in a pH-regulated nanopore by a multi-ion model. The model takes into account surface protonation/deprotonation reactions, surface curvature, electroosmotic flow, Stern layer, and electric double layer overlap. The proposed model is validated by good agreement with the existing experimental data on nanopore conductance with and without a gate voltage. The results show that the modulation of proton transport in a nanopore depends on the concentration of the background salt and solution pH. Without background salt, the gated nanopore exhibits an interesting ambipolar conductance behavior when pH is close to the isoelectric point of the dielectric pore material, and the net ionic and proton conductance can be actively regulated with a gate voltage as low as 1 V. The higher the background salt concentration, the lower is the performance of the gate control on the proton transport.

Method of generating hydrogen by catalytic decomposition of water

DOEpatents

Balachandran, Uthamalingam; Dorris, Stephen E.; Bose, Arun C.; Stiegel, Gary J.; Lee, Tae-Hyun

2002-01-01

A method for producing hydrogen includes providing a feed stream comprising water; contacting at least one proton conducting membrane adapted to interact with the feed stream; splitting the water into hydrogen and oxygen at a predetermined temperature; and separating the hydrogen from the oxygen. Preferably the proton conducting membrane comprises a proton conductor and a second phase material. Preferable proton conductors suitable for use in a proton conducting membrane include a lanthanide element, a Group VIA element and a Group IA or Group IIA element such as barium, strontium, or combinations of these elements. More preferred proton conductors include yttrium. Preferable second phase materials include platinum, palladium, nickel, cobalt, chromium, manganese, vanadium, silver, gold, copper, rhodium, ruthenium, niobium, zirconium, tantalum, and combinations of these. More preferably second phase materials suitable for use in a proton conducting membrane include nickel, palladium, and combinations of these. The method for generating hydrogen is preferably preformed in the range between about 600.degree. C. and 1,700.degree. C.

H3PO4 imbibed polyacrylamide-graft-chitosan frameworks for high-temperature proton exchange membranes

NASA Astrophysics Data System (ADS)

Yuan, Shuangshuang; Tang, Qunwei; He, Benlin; Chen, Haiyan; Li, Qinghua; Ma, Chunqing; Jin, Suyue; Liu, Zhichao

2014-03-01

Proton exchange membrane (PEM), transferring protons from anode to cathode, is a key component in a PEM fuel cell. In the current work, a new class of PEMs are synthesized benefiting from the imbibition behavior of three-dimensional (3D) polyacrylamide-graft-chitosan (PAAm-graft-chitosan) frameworks to H3PO4 aqueous solution. Interconnected 3D framework of PAAm-graft-chitosan provides tremendous space for holding proton-conducting H3PO4. The highest anhydrous proton conductivity of 0.13 S cm-1 at 165 °C is obtained. A fuel cell using a thick membrane as a PEM showed a peak power density of 405 mW cm-2 with O2 and H2 as the oxidant and fuel, respectively. Results indicate that the interconnected 3D framework provides superhighway for proton conduction. The valued merits on anhydrous proton conductivity, huge H3PO4 loading, and easy synthesis promise the new membranes to be good alternatives as high-temperature PEMs.

Morphology and Proton Transport in Sulfonated Block Copolymer and Mesoporous Polymer Electrolyte Membranes

NASA Astrophysics Data System (ADS)

Chen, Chelsea; Wong, David; Beers, Keith; Balsara, Nitash

2013-03-01

In an effort to understand the fundamentals of proton transport in polymer electrolyte membranes (PEMs), we have developed a series of poly(styrene-b-ethylene-b-styrene) (SES) membranes. The SES membranes were subsequently sulfonated to yield proton conducting S-SES membranes. We examine the effects of sulfonation level, temperature and thermal history on the morphology of S-SES membranes in both dry and hydrated states. The effects of these parameters on water uptake and proton transport characteristics of the membranes are also examined. Furthermore, building upon the strategy we deployed in sulfonating the SES membranes, we fabricated mesoporous S-SES membranes, with pores lined up with the proton conducting channels. These membranes have three distinct phases: structural block, proton-conducting block, and void. We examine the effects of pore size, domain structure and sulfonation level on water uptake and proton conductivity of the mesoporous PEMs at different temperatures. This work is funded by Department of Energy.

Facilitating Proton Transport in Nafion-Based Membranes at Low Humidity by Incorporating Multifunctional Graphene Oxide Nanosheets.

PubMed

He, Xueyi; He, Guangwei; Zhao, Anqi; Wang, Fei; Mao, Xunli; Yin, Yongheng; Cao, Li; Zhang, Bei; Wu, Hong; Jiang, Zhongyi

2017-08-23

Nafion, as a state-of-the-art solid electrolyte for proton exchange membrane fuel cells (PEMFCs), suffers from drastic decline in proton conductivity with decreasing humidity, which significantly restricts the efficient and stable operation of the fuel cell system. In this study, the proton conductivity of Nafion at low relative humidity (RH) was remarkably enhanced by incorporating multifunctional graphene oxide (GO) nanosheets as multifunctional fillers. Through surface-initiated atom transfer radical polymerization of sulfopropyl methacrylate (SPM) and poly(ethylene glycol) methyl ether methacrylate, the copolymer-grafted GO was synthesized and incorporated into the Nafion matrix, generating efficient paths at the Nafion-GO interface for proton conduction. The Lewis basic oxygen atoms of ethylene oxide (EO) units and sulfonated acid groups of SPM monomers served as additional proton binding and release sites to facilitate the proton hopping through the membrane. Meanwhile, the hygroscopic EO units enhanced the water retention property of the composite membrane, conferring a dramatic increase in proton conductivity under low humidity. With 1 wt % filler loading, the composite membrane displayed the highest proton conductivity of 2.98 × 10 -2 S cm -1 at 80 °C and 40% RH, which was 10 times higher than that of recast Nafion. Meanwhile, the Nafion composite exhibited a 135.5% increase in peak power density at 60 °C and 50% RH, indicating its great application potential in PEMFCs.

Inorganic-based proton conductive composite membranes for elevated temperature and reduced relative humidity PEM fuel cells

NASA Astrophysics Data System (ADS)

Wang, Chunmei

Proton exchange membrane (PEM) fuel cells are regarded as highly promising energy conversion systems for future transportation and stationary power generation and have been under intensive investigations for the last decade. Unfortunately, cutting edge PEM fuel cell design and components still do not allow economically commercial implementation of this technology. The main obstacles are high cost of proton conductive membranes, low-proton conductivity at low relative humidity (RH), and dehydration and degradation of polymer membranes at high temperatures. The objective of this study was to develop a systematic approach to design a high proton conductive composite membrane that can provide a conductivity of approximately 100 mS cm-1 under hot and dry conditions (120°C and 50% RH). The approach was based on fundamental and experimental studies of the proton conductivity of inorganic additives and composite membranes. We synthesized and investigated a variety of organic-inorganic Nafion-based composite membranes. In particular, we analyzed their fundamental properties, which included thermal stability, morphology, the interaction between inorganic network and Nafion clusters, and the effect of inorganic phase on the membrane conductivity. A wide range of inorganic materials was studied in advance in order to select the proton conductive inorganic additives for composite membranes. We developed a conductivity measurement method, with which the proton conductivity characteristics of solid acid materials, zirconium phosphates, sulfated zirconia (S-ZrO2), phosphosilicate gels, and Santa Barbara Amorphous silica (SBA-15) were discussed in detail. Composite membranes containing Nafion and different amounts of functionalized inorganic additives (sulfated inorganics such as S-ZrO2, SBA-15, Mobil Composition of Matter MCM-41, and S-SiO2, and phosphonated inorganic P-SiO2) were synthesized with different methods. We incorporated inorganic particles within Nafion clusters either by mixing inorganic gels or solutions with Nafion solution followed by membrane casting or by blending inorganic powders with Nafion solution. The membrane properties, such as acidity, swelling, water uptake, thermostability, proton conductivity, and electrochemical performance, were explored in depth. We characterized the inorganic phase inside composite membranes and its interaction with the Nafion matrix by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). Furthermore, we discussed the effect of these inorganic conductors' properties, such as particle size, conductivity, and interaction between functional groups and the Nafion, on the membrane conductivity. The contribution of hydrophilic inorganic particles in improving the membrane fuel cell performance was numerically analyzed by Tafel plot. Finally, the proton conductivity phenomena in composite membranes were simulated with two proton-transport models; one was based on the rule of mixtures, and the other was described by generalized Stefan-Maxwell equations. In the simulation, we proposed a new route in rational design of high proton-conductive composite membranes.

Low proton conductance of plant cuticles and its relevance to the acid-growth theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dreyer, S.A.; Seymour, V.; Cleland, R.E.

1981-09-01

Evidence obtained on the relation between the pH of the medium and the growth of intact stem sections is compatible with the acid-growth theory only if the proton conductance of the cuticle is an effective barrier to the entry or exit of protons from the tissue. By measuring the rate at which protons cross frozen-thawed epidermal strips of sunflower (Helianthus annus L.) and soybean hypocotyls (Glycine max Morr.) and enzymically isolated cuticles of Berberis aquifolium Persh. and tomato (Lycopersicum esculentum Mill.) fruit, we have now demonstrated the low proton conductance of the cuticular layer. Unless the conductance is enhanced bymore » abrasion of the cuticle or by removal of the cuticular waxes, proton movement into and out of a tissue across the cuticle will be significant only over long time periods.« less

Enhanced proton conductivity by the influence of modified montmorillonite on poly (vinyl alcohol) based blend composite membranes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Palani, P. Bahavan, E-mail: bahavanpalani@gmail.com; Abidin, K. Sainul; Kannan, R., E-mail: rksrsrk@gmail.com

2016-05-23

The highest proton conductivity value of 0.0802 Scm{sup −1} is obtained at 6 wt% of protonated MMT added to the PVA/PEG blends. The polymer blend composite membranes are prepared with varied concentration of Poly vinyl alcohol (PVA), Poly ethylene glycol (PEG) and Montmorillonite (MMT) by solution casting method. The Na{sup +} MMT was modified (protonated) to H{sup +} MMT with ion exchange process. The prepared membranes were characterized by using TGA, FTIR, XRD, Ion Exchange Capacity, Water/Methanol uptake, swelling ratio and proton conductivity. The significant improvements in the hydrolytic stability were observed. In addition, thermal stability of the composite membranesmore » were improved and controlled by the addition of MMT. All the prepared membranes are shown appreciable values of proton conductivity at room temperature with 100% relative humidity.« less

Mitochondrial Proton Leak Plays a Critical Role in Pathogenesis of Cardiovascular Diseases.

PubMed

Cheng, Jiali; Nanayakkara, Gayani; Shao, Ying; Cueto, Ramon; Wang, Luqiao; Yang, William Y; Tian, Ye; Wang, Hong; Yang, Xiaofeng

2017-01-01

Mitochondrial proton leak is the principal mechanism that incompletely couples substrate oxygen to ATP generation. This chapter briefly addresses the recent progress made in understanding the role of proton leak in the pathogenesis of cardiovascular diseases. Majority of the proton conductance is mediated by uncoupling proteins (UCPs) located in the mitochondrial inner membrane. It is evident that the proton leak and reactive oxygen species (ROS) generated from electron transport chain (ETC) in mitochondria are linked to each other. Increased ROS production has been shown to induce proton conductance, and in return, increased proton conductance suppresses ROS production, suggesting the existence of a positive feedback loop that protects the biological systems from detrimental effects of augmented oxidative stress. There is mounting evidence attributing to proton leak and uncoupling proteins a crucial role in the pathogenesis of cardiovascular disease. We can surmise the role of "uncoupling" in cardiovascular disorders as follows; First, the magnitude of the proton leak and the mechanism involved in mediating the proton leak determine whether there is a protective effect against ischemia-reperfusion (IR) injury. Second, uncoupling by UCP2 preserves vascular function in diet-induced obese mice as well as in diabetes. Third, etiology determines whether the proton conductance is altered or not during hypertension. And fourth, proton leak regulates ATP synthesis-uncoupled mitochondrial ROS generation, which determines pathological activation of endothelial cells for recruitment of inflammatory cells. Continue effort in improving our understanding in the role of proton leak in the pathogenesis of cardiovascular and metabolic diseases would lead to identification of novel therapeutic targets for treatment.

Proton conductivity in ampullae of Lorenzini jelly

PubMed Central

Josberger, Erik E.; Hassanzadeh, Pegah; Deng, Yingxin; Sohn, Joel; Rego, Michael J.; Amemiya, Chris T.; Rolandi, Marco

2016-01-01

In 1678, Stefano Lorenzini first described a network of organs of unknown function in the torpedo ray—the ampullae of Lorenzini (AoL). An individual ampulla consists of a pore on the skin that is open to the environment, a canal containing a jelly and leading to an alveolus with a series of electrosensing cells. The role of the AoL remained a mystery for almost 300 years until research demonstrated that skates, sharks, and rays detect very weak electric fields produced by a potential prey. The AoL jelly likely contributes to this electrosensing function, yet the exact details of this contribution remain unclear. We measure the proton conductivity of the AoL jelly extracted from skates and sharks. The room-temperature proton conductivity of the AoL jelly is very high at 2 ± 1 mS/cm. This conductivity is only 40-fold lower than the current state-of-the-art proton-conducting polymer Nafion, and it is the highest reported for a biological material so far. We suggest that keratan sulfate, identified previously in the AoL jelly and confirmed here, may contribute to the high proton conductivity of the AoL jelly with its sulfate groups—acid groups and proton donors. We hope that the observed high proton conductivity of the AoL jelly may contribute to future studies of the AoL function. PMID:27386543

High temperature proton exchange membranes with enhanced proton conductivities at low humidity and high temperature based on polymer blends and block copolymers of poly(1,3-cyclohexadiene) and poly(ethylene glycol)

DOE PAGES

Deng, Shawn; Hassan, Mohammad K.; Nalawade, Amol; ...

2015-09-16

Hot (at 120 °C) and dry (20% relative humidity) operating conditions benefit fuel cell designs based on proton exchange membranes (PEMs) and hydrogen due to simplified system design and increasing tolerance to fuel impurities. In this paper, presented are preparation, partial characterization, and multi-scale modeling of such PEMs based on cross-linked, sulfonated poly(1,3-cyclohexadiene) (xsPCHD) blends and block copolymers with poly(ethylene glycol) (PEG). These low cost materials have proton conductivities 18 times that of current industry standard Nafion at hot, dry operating conditions. Among the membranes studied, the blend xsPCHD-PEG PEM displayed the highest proton conductivity, which exhibits a morphology withmore » higher connectivity of the hydrophilic domain throughout the membrane. Simulation and modeling provide a molecular level understanding of distribution of PEG within this hydrophilic domain and its relation to proton conductivities. Finally, this study demonstrates enhancement of proton conductivity at high temperature and low relative humidity by incorporation of PEG and optimized sulfonation conditions.« less

Insight into proton transfer in phosphotungstic acid functionalized mesoporous silica-based proton exchange membrane fuel cells.

PubMed

Zhou, Yuhua; Yang, Jing; Su, Haibin; Zeng, Jie; Jiang, San Ping; Goddard, William A

2014-04-02

We have developed for fuel cells a novel proton exchange membrane (PEM) using inorganic phosphotungstic acid (HPW) as proton carrier and mesoporous silica as matrix (HPW-meso-silica) . The proton conductivity measured by electrochemical impedance spectroscopy is 0.11 S cm(-1) at 90 °C and 100% relative humidity (RH) with a low activation energy of ∼14 kJ mol(-1). In order to determine the energetics associated with proton migration within the HPW-meso-silica PEM and to determine the mechanism of proton hopping, we report density functional theory (DFT) calculations using the generalized gradient approximation (GGA). These DFT calculations revealed that the proton transfer process involves both intramolecular and intermolecular proton transfer pathways. When the adjacent HPWs are close (less than 17.0 Å apart), the calculated activation energy for intramolecular proton transfer within a HPW molecule is higher (29.1-18.8 kJ/mol) than the barrier for intermolecular proton transfer along the hydrogen bond. We find that the overall barrier for proton movement within the HPW-meso-silica membranes is determined by the intramolecular proton transfer pathway, which explains why the proton conductivity remains unchanged when the weight percentage of HPW on meso-silica is above 67 wt %. In contrast, the activation energy of proton transfer on a clean SiO2 (111) surface is computed to be as high as ∼40 kJ mol(-1), confirming the very low proton conductivity on clean silica surfaces observed experimentally.

A comparative study of nano-SiO2 and nano-TiO2 fillers on proton conductivity and dielectric response of a silicotungstic acid-H3PO4-poly(vinyl alcohol) polymer electrolyte.

PubMed

Gao, Han; Lian, Keryn

2014-01-08

The effects of nano-SiO2 and nano-TiO2 fillers on a thin film silicotungstic acid (SiWA)-H3PO4-poly(vinyl alcohol) (PVA) proton conducting polymer electrolyte were studied and compared with respect to their proton conductivity, environmental stability, and dielectric properties, across a temperature range from 243 to 323 K. Three major effects of these fillers have been identified: (a) barrier effect; (b) intrinsic dielectric constant effect; and (c) water retention effect. Dielectric analyses were used to differentiate these effects on polymer electrolyte-enabled capacitors. Capacitor performance was correlated to electrolyte properties through dielectric constant and dielectric loss spectra. Using a single-ion approach, proton density and proton mobility of each polymer electrolyte were derived as a function of temperature. The results allow us to deconvolute the different contributions to proton conductivity in SiWA-H3PO4-PVA-based electrolytes, especially in terms of the effects of fillers on the dynamic equilibrium of free protons and protonated water in the electrolytes.

Proton conducting membrane using a solid acid

NASA Technical Reports Server (NTRS)

Haile, Sossina M. (Inventor); Chisholm, Calum (Inventor); Boysen, Dane (Inventor); Narayanan, Sekharipuram R. (Inventor)

2002-01-01

A solid acid material is used as a proton conducting membrane in an electrochemical device. The solid acid material can be one of a plurality of different kinds of materials. A binder can be added, and that binder can be either a nonconducting or a conducting binder. Nonconducting binders can be, for example, a polymer or a glass. A conducting binder enables the device to be both proton conducting and electron conducting. The solid acid material has the general form M.sub.a H.sub.b (XO.sub.t).sub.c.

Coordination-chemistry control of proton conductivity in the iconic metal-organic framework material HKUST-1.

PubMed

Jeong, Nak Cheon; Samanta, Bappaditya; Lee, Chang Yeon; Farha, Omar K; Hupp, Joseph T

2012-01-11

HKUST-1, a metal-organic framework (MOF) material containing Cu(II)-paddlewheel-type nodes and 1,3,5-benzenetricarboxylate struts, features accessible Cu(II) sites to which solvent or other desired molecules can be intentionally coordinated. As part of a broader investigation of ionic conductivity in MOFs, we unexpectedly observed substantial proton conductivity with the "as synthesized" version of this material following sorption of methanol. Although HKUST-1 is neutral, coordinated water molecules are rendered sufficiently acidic by Cu(II) to contribute protons to pore-filling methanol molecules and thereby enhance the alternating-current conductivity. At ambient temperature, the chemical identities of the node-coordinated and pore-filling molecules can be independently varied, thus enabling the proton conductivity to be reversibly modulated. The proton conductivity of HKUST-1 was observed to increase by ~75-fold, for example, when node-coordinated acetonitrile molecules were replaced by water molecules. In contrast, the conductivity became almost immeasurably small when methanol was replaced by hexane as the pore-filling solvent. © 2011 American Chemical Society

Pressure-induced amorphization of a dense coordination polymer and its impact on proton conductivity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Umeyama, Daiki; Hagi, Keisuke; Ogiwara, Naoki

2014-12-01

The proton conductivity of a dense coordination polymer (CP) was investigated under high-pressure conditions. Impedance measurements under high pressures revealed that the proton conductivity of the CP decreased more than 1000-fold at pressures of 3–7 GPa and that the activation energy for proton conduction almost doubled compared with that at ambient pressure. A synchrotron X-ray study under high pressure identified the amorphization process of the CP during compression, which rationally explains the decrease in conductivity and increase in activation energy. This phenomenon is categorized as reversible pressure-induced amorphization of a dense CP and is regarded as a demonstration of themore » coupling of the mechanical and electrical properties of a CP.« less

Enhanced proton transport in nanostructured polymer electrolyte/ionic liquid membranes under water-free conditions.

PubMed

Kim, Sung Yeon; Kim, Suhan; Park, Moon Jeong

2010-10-05

Proton exchange fuel cells (PEFCs) have the potential to provide power for a variety of applications ranging from electronic devices to transportation vehicles. A major challenge towards economically viable PEFCs is finding an electrolyte that is both durable and easily passes protons. In this article, we study novel anhydrous proton-conducting membranes, formed by incorporating ionic liquids into synthetic block co-polymer electrolytes, poly(styrenesulphonate-b-methylbutylene) (S(n)MB(m)), as high-temperature PEFCs. The resulting membranes are transparent, flexible and thermally stable up to 180 °C. The increases in the sulphonation level of S(n)MB(m) co-polymers (proton supplier) and the concentration of the ionic liquid (proton mediator) produce an overall increase in conductivity. Morphology effects were studied by X-ray scattering and electron microscopy. Compared with membranes having discrete ionic domains (including Nafion 117), the nanostructured membranes revealed over an order of magnitude increase in conductivity with the highest conductivity of 0.045 S cm(-1) obtained at 165 °C.

PREFACE: Transport phenomena in proton conducting media Transport phenomena in proton conducting media

NASA Astrophysics Data System (ADS)

Eikerling, Michael

2011-06-01

Proton transport phenomena are of paramount importance for acid-base chemistry, energy transduction in biological organisms, corrosion processes, and energy conversion in electrochemical systems such as polymer electrolyte fuel cells. The relevance for such a plethora of materials and systems, and the ever-lasting fascination with the highly concerted nature of underlying processes drive research across disciplines in chemistry, biology, physics and chemical engineering. A proton never travels alone. Proton motion is strongly correlated with its environment, usually comprised of an electrolyte and a solid or soft host material. For the transport in nature's most benign proton solvent and shuttle, water that is, insights from ab initio simulations, matured over the last 15 years, have furnished molecular details of the structural diffusion mechanism of protons. Excess proton movement in water consists of sequences of Eigen-Zundel-Eigen transitions, triggered by hydrogen bond breaking and making in the surrounding water network. Nowadays, there is little debate about the validity of this mechanism in water, which bears a stunning resemblance to the basic mechanistic picture put forward by de Grotthuss in 1806. While strong coupling of an excess proton with degrees of freedom of solvent and host materials facilitates proton motion, this coupling also creates negative synergies. In general, proton mobility in biomaterials and electrochemical proton conducting media is highly sensitive to the abundance and structure of the proton solvent. In polymer electrolyte membranes, in which protons are bound to move in nano-sized water-channels, evaporation of water or local membrane dehydration due to electro-osmotic coupling are well-known phenomena that could dramatically diminish proton conductivity. Contributions in this special issue address various vital aspects of the concerted nature of proton motion and they elucidate important structural and dynamic effects of solvent, charge-bearing species at interfaces and porous host materials on proton transport properties. As a common thread, articles in this special issue contribute to understanding the functionality provided by complex materials, beyond hydrogen bond fluctuations in water. The first group of articles (Smirnov et al, Henry et al, Medvedev and Stuchebrukhov) elucidates various aspects of the impact of local structural fluctuations, hydrogen bonding and long-range electrostatic forces on proton transfer across and at the surface of mitochondrial membranes. The second group of articles (Ilhan and Spohr, Allahyarov et al and Idupulapati et al) employ molecular dynamics simulations to rationalize vital dependencies of proton transport mechanisms in aqueous-based polymer electrolyte membranes on the nanoporous, phase-separated ionomer morphology, and on the level of hydration. The articles by Gebel et al, Boillat et al, and Aleksandrova et al employ small angle neutron scattering, neutron radiography, and electrochemical atomic force microscopy, respectively, to obtain detailed insights into the kinetics of water sorption, water distribution, water transport properties, as well as spatial maps of proton conductivity in fuel cell membranes. The contribution of Paschos et al provides a comprehensive review of phosphate-based solid state protonic conductors for intermediate temperature fuel cells. The topic of proton conductive materials for high-temperature, water-free operation of fuel cells is continued in the article of Verbraeken et al which addresses synthesis and characterization of a proton conducting perovskite. The guest editor wishes to acknowledge and thank all contributing authors for their commitment to this special issue. Moreover, I would like to thank the staff at IOP Publishing for coordinating submission and refereeing processes. Finally, for the readers, I hope that this special issue will be a valuable and stimulating source of insights into the versatile and eminently important field of transport phenomena in proton conducting media. Complex dynamics of fluids in disordered and crowded environments contents Electrostatic models of electron-driven proton transfer across a lipid membrane Anatoly Yu Smirnov, Lev G Mourokh and Franco Nori Molecular basis of proton uptake in single and double mutants of cytochrome c oxidase Rowan M Henry, David Caplan, Elisa Fadda and Régis Pomès Proton diffusion along biological membranes E S Medvedev and A A Stuchebrukhov Ab initio molecular dynamics of proton networks in narrow polymer electrolyte pores Mehmet A Ilhan and Eckhard Spohr A simulation study of field-induced proton-conduction pathways in dry ionomers Elshad Allahyarov, Philip L Taylor and Hartmut Löwen Molecular structure and transport dynamics in perfluoro sulfonyl imide membranes Nagesh Idupulapati, Ram Devanathan and Michel Dupuis The kinetics of water sorption in Nafion membranes: a small-angle neutron scattering study Gérard Gebel, Sandrine Lyonnard, Hakima Mendil-Jakani and Arnaud Morin Using 2H labeling with neutron radiography for the study of solid polymer electrolyte water transport properties P Boillat, P Oberholzer, B C Seyfang, A Kästner, R Perego, G G Scherer, E H Lehmann and A Wokaun Spatial distribution and dynamics of proton conductivity in fuel cell membranes: potential and limitations of electrochemical atomic force microscopy measurements E Aleksandrova, S Hink, R Hiesgen and E Roduner A review on phosphate based, solid state, protonic conductors for intermediate temperature fuel cells O Paschos, J Kunze, U Stimming and F Maglia A structural study of the proton conducting B-site ordered perovskite Ba3Ca1.18Ta1.82O8.73 Maarten C Verbraeken, Hermenegildo A L Viana, Philip Wormald and John T S Irvine

Stereochemistry-Dependent Proton Conduction in Proton Exchange Membrane Fuel Cells.

PubMed

Thimmappa, Ravikumar; Devendrachari, Mruthyunjayachari Chattanahalli; Kottaichamy, Alagar Raja; Tiwari, Omshanker; Gaikwad, Pramod; Paswan, Bhuneshwar; Thotiyl, Musthafa Ottakam

2016-01-12

Graphene oxide (GO) is impermeable to H2 and O2 fuels while permitting H(+) shuttling, making it a potential candidate for proton exchange membrane fuel cells (PEMFC), albeit with a large anisotropy in their proton transport having a dominant in plane (σIP) contribution over the through plane (σTP). If GO-based membranes are ever to succeed in PEMFC, it inevitably should have a dominant through-plane proton shuttling capability (σTP), as it is the direction in which proton gets transported in a real fuel-cell configuration. Here we show that anisotropy in proton conduction in GO-based fuel cell membranes can be brought down by selectively tuning the geometric arrangement of functional groups around the dopant molecules. The results show that cis isomer causes a selective amplification of through-plane proton transport, σTP, pointing to a very strong geometry angle in ionic conduction. Intercalation of cis isomer causes significant expansion of GO (001) planes involved in σTP transport due to their mutual H-bonding interaction and efficient bridging of individual GO planes, bringing down the activation energy required for σTP, suggesting the dominance of a Grotthuss-type mechanism. This isomer-governed amplification of through-plane proton shuttling resulted in the overall boosting of fuel-cell performance, and it underlines that geometrical factors should be given prime consideration while selecting dopant molecules for bringing down the anisotropy in proton conduction and enhancing the fuel-cell performance in GO-based PEMFC.

Proton transport behavior through the influenza A M2 channel: insights from molecular simulation.

PubMed

Chen, Hanning; Wu, Yujie; Voth, Gregory A

2007-11-15

The structural properties of the influenza A virus M2 transmembrane channel in dimyristoylphosphatidylcholine bilayer for each of the four protonation states of the proton-gating His-37 tetrad and their effects on proton transport for this low-pH activated, highly proton-selective channel are studied by classical molecular dynamics with the multistate empirical valence-bond (MS-EVB) methodology. The excess proton permeation free energy profile and maximum ion conductance calculated from the MS-EVB simulation data combined with the Poisson-Nernst-Planck theory indicates that the triply protonated His-37 state is the most likely open state via a significant side-chain conformational change of the His-37 tetrad. This proposed open state of M2 has a calculated proton permeation free energy barrier of 7 kcal/mol and a maximum conductance of 53 pS compared to the experimental value of 6 pS. By contrast, the maximum conductance for Na(+) is calculated to be four orders of magnitude lower, in reasonable agreement with the experimentally observed proton selectivity. The pH value to activate the channel opening is estimated to be 5.5 from dielectric continuum theory, which is also consistent with experimental results. This study further reveals that the Ala-29 residue region is the primary binding site for the antiflu drug amantadine (AMT), probably because that domain is relatively spacious and hydrophobic. The presence of AMT is calculated to reduce the proton conductance by 99.8% due to a significant dehydration penalty of the excess proton in the vicinity of the channel-bound AMT.

Proton Conductivity in Phosphoric Acid: The Role of Quantum Effects

DOE PAGES

Heres, M.; Wang, Y.; Griffin, P. J.; ...

2016-10-07

Phosphoric acid has one of the highest intrinsic proton conductivities of any known liquids, and the mechanism of this exceptional conductivity remains a puzzle. In our detailed experimental studies we discovered a strong isotope effect in the conductivity of phosphoric acids caused by (i) a strong isotope shift of the glass transition temperature and (ii) a significant reduction of the energy barrier by zero-point quantum fluctuations. Our results suggest that the high conductivity in phosphoric acids is caused by a very efficient proton transfer mechanism, which is strongly assisted by quantum effects.

Proton conductive montmorillonite-Nafion composite membranes for direct ethanol fuel cells

NASA Astrophysics Data System (ADS)

Wu, Xiu-Wen; Wu, Nan; Shi, Chun-Qing; Zheng, Zhi-Yuan; Qi, Hong-Bin; Wang, Ya-Fang

2016-12-01

The preparation of Nafion membranes modified with montmorillonites is less studied, and most relative works mainly applied in direct methanol fuel cells, less in direct ethanol fuel cells. Organic/inorganic composite membranes are prepared with different montmorillonites (Ca-montmorillonite, Na-montmorillonite, K-montmorillonite, Mg-montmorillonite, and H-montmorillonite) and Nafion solution via casting method at 293 K in air, and with balance of their proton conductivity and ethanol permeability. The ethanol permeability and proton conductivity of the membranes are comparatively studied. The montmorillonites can well decrease the ethanol permeability of the membranes via inserted them in the membranes, while less decrease the proton conductivities of the membranes depending on the inserted amount and type of montmorillonites. The proton conductivities of the membranes are between 36.0 mS/cm and 38.5 mS/cm. The ethanol permeability of the membranes is between 0.69 × 10-6 cm2/s and 2.67 × 10-6 cm2/s.

Anisotropic proton-conducting membranes prepared from swift heavy ion-beam irradiated ETFE films

NASA Astrophysics Data System (ADS)

Kimura, Yosuke; Chen, Jinhua; Asano, Masaharu; Maekawa, Yasunari; Katakai, Ryoichi; Yoshida, Masaru

2007-10-01

Poly(ethylene-co-tetrafluoroethylene) (ETFE) films were irradiated by swift heavy ion-beams of 129Xe 23+ with fluences of 0, 3 × 10 6, 3 × 10 7, 3 × 10 8 and 3 × 10 9 ions/cm 2, followed by γ-ray pre-irradiation for radiation grafting of styrene onto the ETFE films and sulfonation of the grafted ETFE films to prepare highly anisotropic proton-conducting membranes. The fluence of Xe ions and the addition of water in the grafting solvent were examined to determine their effect on the proton conductivity of the resultant membranes. It was found that the polymer electrolyte membrane prepared by grafting the styrene monomer in a mixture of 67% isopropanol and 33% water to the ETFE film with an ion-beam irradiation fluence of 3.0 × 10 6 ions/cm 2 was a highly anisotropic proton-conducting material, as the proton conductivity was three or more times higher in the thickness direction than in the surface direction of the membrane.

A Study of influence on sulfonated TiO2-Poly (Vinylidene fluoride-co-hexafluoropropylene) nano composite membranes for PEM Fuel cell application

NASA Astrophysics Data System (ADS)

kumar, K. Selva; Rajendran, S.; Prabhu, M. Ramesh

2017-10-01

The present work describes the sulfonated Titania directly blended with Poly (Vinylidene fluoride-co-hexafluoropropylene) as a host polymer by solvent casting technique for PEM fuel cell application. Characterization studies such as FT-IR, SEM, EDX, AFM, Proton conductivity, contact angle measurement, IEC, TG, water uptake, tensile strength were performed by for synthesized proton conducting polymer electrolytes. The maximum proton conductivity value was found to be 3.6 × 10-3S/cm for 25 wt% sulfonated Titania based system at 80 °C. The temperature dependent proton conductivity of the polymer electrolyte follows an Arrhenius relationship. Surface morphology of the composite membranes was investigated by tapping mode. Thermal stability of the system was studied by TG analysis. The fabricated composite membranes with high proton conductivity, good water uptake and IEC parameters exhibited a maximum fuel cell power density of 85 Mw/cm2for PEM fuel cell application.

Classical Molecular Dynamics with Mobile Protons.

PubMed

Lazaridis, Themis; Hummer, Gerhard

2017-11-27

An important limitation of standard classical molecular dynamics simulations is the inability to make or break chemical bonds. This restricts severely our ability to study processes that involve even the simplest of chemical reactions, the transfer of a proton. Existing approaches for allowing proton transfer in the context of classical mechanics are rather cumbersome and have not achieved widespread use and routine status. Here we reconsider the combination of molecular dynamics with periodic stochastic proton hops. To ensure computational efficiency, we propose a non-Boltzmann acceptance criterion that is heuristically adjusted to maintain the correct or desirable thermodynamic equilibria between different protonation states and proton transfer rates. Parameters are proposed for hydronium, Asp, Glu, and His. The algorithm is implemented in the program CHARMM and tested on proton diffusion in bulk water and carbon nanotubes and on proton conductance in the gramicidin A channel. Using hopping parameters determined from proton diffusion in bulk water, the model reproduces the enhanced proton diffusivity in carbon nanotubes and gives a reasonable estimate of the proton conductance in gramicidin A.

High conductive, long-term durable, anhydrous proton conductive solid-state electrolyte based on a metal-organic framework impregnated with binary ionic liquids: Synthesis, characteristic and effect of anion

NASA Astrophysics Data System (ADS)

Chen, Hui; Han, Shu-Yan; Liu, Rui-Heng; Chen, Teng-Fei; Bi, Kai-Lun; Liang, Jian-Bo; Deng, Yu-Heng; Wan, Chong-Qing

2018-02-01

Incorporating ionic liquids (abbreviated as ILs) into porous metal-organic framework (MOF) to obtain ILs@MOF nanocomposites is documented as a feasible method to achieve new type of anhydrous proton conductor with high performance. We newly synthesized a series of ILs with different acid counter anions (R-SO3-) and their ILs@MOF hybrid materials, i.e. SA-EIMS@MIL-101, MSA-EIMS@MIL-101 and PTSA-EIMS@MIL-101 (SA = sulfate acid, MSA = methanesulfonate acid, PTSA = p-toluenesulfonate acid, EIMS = 1-(1-ethyl-3-imidazolium)propane-3-sulfonate). Such hybrid materials displayed as anhydrous proton conduction with long-term durability even heated at 150 °C open to air. σ value of SA-EIMS@MIL-101 is up to 1.89 × 10-3 S cm-1, being in the range of the most conductive MOF-based materials. MOF support exhibited favorable proton transport and long-term retention for ILs. Anion volumes of R-SO3- displayed significant effects on the proton conductivity of such hybrid ILs@MOF materials. The smaller the van der Waals volume of R-SO3- is, the higher the conductivity of ILs@MOF is. This work suggests that the combination of a variety of the incorporated ILs and a MOF framework would afford high proton transport and gives an idea to explore the safe, anhydrous, solid-state electrolyte for high temperature proton exchange membrane fuel cell.

Cellulose nanofiber-embedded sulfonated poly (ether sulfone) membranes for proton exchange membrane fuel cells.

PubMed

Xu, Xianlin; Li, Rui; Tang, Chenxiao; Wang, Hang; Zhuang, Xupin; Liu, Ya; Kang, Weimin; Shi, Lei

2018-03-15

Cellulose nanofibers were embedded into sulfonated poly (ether sulfone) matrix to heighten the water retention and proton conductivity of proton exchange membranes (PEMs). Cellulose nanofibers were obtained by hydrolyzing cellulose acetate nanofibers, which were prepared via electrostatic-induction-assisted solution blow spinning. Morphology, thermal stability, and mechanical properties of the PEMs were investigated. The results showed that proton conductivity, water uptake, and methanol permeability of the composite membranes were improved. Hydrophilicity of the composite membranes was gradually improved with the addition of nanofibers. When the content of nanofibers was 5 wt%, the highest proton conductivity was 0.13 S/cm (80 °C, 100% RH). Therefore, the cellulose nanofiber could be used as support materials to enhance the performance of proton exchange membranes, the composite membranes have potential application in Direct methanol fuel cells (DMFCs). Copyright © 2017 Elsevier Ltd. All rights reserved.

Why do proton conducting polybenzimidazole phosphoric acid membranes perform well in high-temperature PEM fuel cells?

PubMed

Melchior, Jan-Patrick; Majer, Günter; Kreuer, Klaus-Dieter

2016-12-21

Transport properties and hydration behavior of phosphoric acid/(benz)imidazole mixtures are investigated by diverse NMR techniques, thermogravimetric analysis (TGA) and conductivity measurements. The monomeric systems can serve as models for phosphoric acid/poly-benzimidazole membranes which are known for their exceptional performance in high temperature PEM fuel cells. 1 H- and 31 P-NMR data show benzimidazole acting as a strong Brønsted base with respect to neat phosphoric acid. Since benzimidazole's nitrogens are fully protonated with a low rate for proton exchange with phosphate species, proton diffusion and conduction processes must take place within the hydrogen bond network of phosphoric acid only. The proton exchange dynamics between phosphate and benzimidazole species pass through the intermediate exchange regime (with respect to NMR line separations) with exchange times being close to typical diffusion times chosen in PFG-NMR diffusion measurements (ms regime). The resulting effects, as described by the Kärger equation, are included into the evaluation of PFG-NMR data for obtaining precise proton diffusion coefficients. The highly reduced proton diffusion coefficient within the phosphoric acid part of the model systems compared to neat phosphoric acid is suggested to be the immediate consequence of proton subtraction from phosphoric acid. This reduces hydrogen bond network frustration (imbalance of the number of proton donors and acceptors) and therefore also the rate of structural proton diffusion, phosphoric acid's acidity and hygroscopicity. Reduced water uptake, shown by TGA, goes along with reduced electroosmotic water drag which is suggested to be the reason for PBI-phosphoric acid membranes performing better in fuel cells than other phosphoric-acid-containing electrolytes with higher protonic conductivity.

Achieving Amphibious Superprotonic Conductivity in a CuI Metal-Organic Framework by Strategic Pyrazinium Salt Impregnation.

PubMed

Khatua, Sajal; Bar, Arun Kumar; Sheikh, Javeed Ahmad; Clearfield, Abraham; Konar, Sanjit

2018-01-19

Treatment of a pyrazine (pz)-impregnated Cu I metal-organic framework (MOF) ([1⊃pz]) with HCl vapor renders an interstitial pyrazinium chloride salt-hybridized MOF ([1⊃pz⋅6 HCl]) that exhibits proton conductivity over 10 -2  S cm -1 both in anhydrous and under humid conditions. Framework [1⊃pz⋅6 HCl] features the highest anhydrous proton conductivity among the lesser-known examples of MOF-based materials exhibiting proton conductivity under both anhydrous and humid conditions. Moreover, [1⊃pz] and corresponding pyrazinium sulfate- and pyrazinium phosphate-hybridized MOFs also exhibit superprotonic conductivity over 10 -2  S cm -1 under humid conditions. The impregnated pyrazinium ions play a crucial role in protonic conductivity, which occurs through a Grotthuss mechanism. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Modification of Nafion membrane with biofunctional SiO2 nanofiber for proton exchange membrane fuel cells

NASA Astrophysics Data System (ADS)

Wang, Hang; Li, Xiaojie; Zhuang, Xupin; Cheng, Bowen; Wang, Wei; Kang, Weimin; Shi, Lei; Li, Hongjun

2017-02-01

Proton currents are an integral part of the most important energy-converting structures in biology. We prepared a new type of bioinspired Nafion (Bio-Nafion) membrane composited of biofunctional SiO2 (Bio-SiO2) nanofiber and Nafion matrix. SiO2 nanofibers were prepared by electrospinning silica sol prepared from tetraethyl orthosilicate. Meanwhile, Bio-SiO2 nanofibers were synthesized by immobilizing amino acids (cysteine, serine, lysine, and glycine) on SiO2 nanofibers, which acted as efficient proton-conducting pathways that involved numerous H+ transport sites. In our study, the SiO2 nanofibers biofunctionalized with cysteine were further oxidized, and the composite membranes were designated as Nafion-Cys, Nafion-Lys, Nafion-Ser, and Nafion-Gly, respectively. We then investigated the different polar groups (sbnd SO3H, sbnd OH, and sbnd NH2) of the amino acids that contributed to membrane properties of thermal stability, water uptake (WU), dimensional stability, proton conductivity, and methanol permeability. Nafion-Cys exhibited the highest proton conductivity of 0.2424 S/cm (80 °C). Nafion-Gly showed the lowest proton conductivity and WU because glycine contains the least number of hydrophilic groups among the amino acids. Overall, the introduction of Bio-SiO2 nanofiber to composite membranes significantly improved proton conductivity, dimensional stability, and methanol permeability.

Structural stability of anhydrous proton conducting SrZr0.9Er0.1O3-δ perovskite ceramic vs. protonation/deprotonation cycling: Neutron diffraction and Raman studies

NASA Astrophysics Data System (ADS)

Slodczyk, Aneta; Colomban, Philippe; Upasen, Settakorn; Grasset, Frédéric; André, Gilles

2015-08-01

Long-term chemical and structural stability of an ion conducting ceramic is one of the main criteria for its selection as an electrolytic membrane in energy plant devices. Consequently, medium density SrZr0.9Er0.1O3-δ (SZE) anhydrous proton conducting ceramic - a potential electrolyte of SOFC/PCFC, was analysed by neutron diffraction between room temperature and 900 °C. After the first heating/cooling cycle, the ceramic pieces were exposed to water vapour pressure in an autoclave (500 °C, 40 bar, 7 days) in order to incorporate protonic species; the protonated compound was then again analysed by neutron diffraction. This procedure was repeated two times. At each step, the sample was also controlled by TGA and Raman spectroscopy. These studies allow the first comprehensive comparison of structural and chemical stability during the protonation/deprotonation cycling. The results reveal good structural stability, although an irreversible small contraction of the unit-cell volume and local structure modifications near Zr/ErO5[] octahedra are detected after the first protonation. After the second protonation easy ceramic crumbling under a stress is observed because of the presence of secondary phases (SrCO3, Sr(OH)2) well detected by Raman scattering and TGA. The role of crystallographic purity, substituting element and residual porosity in the proton conducting perovskite electrolyte stability is discussed.

Effect of water on the low temperature conductivity of polymer electrolytes.

PubMed

Siu, Ana; Schmeisser, Jennifer; Holdcroft, Steven

2006-03-30

The proton conductivity of radiation-grafted ethylenetetrafluoroethylene-grafted-poly(styrene sulfonic) acid (ETFE-g-PSSA) and Nafion 117 membranes between 25 and -37 degrees C is reported. The freezing of water in the membranes, which strongly depends on the internal acid concentration, results in a 4-fold decrease in proton conductivity. The activation energies before and after the freezing of the membranes are approximately 0.15 and 0.4 eV, consistent with proton transport through liquid water and strongly bound water, respectively. Differential scanning calorimetry data show that up to 14 H(2)O molecules per H(+)/SO(3)(-) group remain unfrozen at subzero temperatures and are believed to be responsible for the low temperature conductivity that is observed. These results indicate that proton conductivity in membranes may be achieved via strongly bound and highly polarized water.

Role of Water in Proton-Hydroxide Conductance Across Model and Biological Membranes.

DTIC Science & Technology

1987-11-10

Arlington, VA 22217-5000 61153N RR04108 441K712 11. TITLE (Include Security Classification) Role of water in proton-hydroxide conductance across model and...used the gramicidin channel to test properties of transmembrane strands of hydrogen bonded water which would model such defects. Results are described...Gramicidin as a model "proton wire." 2. Effects of homologous series of alcohols on proton flux in liposomes, and the relationship to their anesthetic

Perfluoroalkyl phosphonic and phosphinic acids as proton conductors for anhydrous proton-exchange membranes.

PubMed

Herath, Mahesha B; Creager, Stephen E; Kitaygorodskiy, Alex; DesMarteau, Darryl D

2010-09-10

A study of proton-transport rates and mechanisms under anhydrous conditions using a series of acid model compounds, analogous to comb-branch perfluorinated ionomers functionalized with phosphonic, phosphinic, sulfonic, and carboxylic acid protogenic groups, is reported. Model compounds are characterized with respect to proton conductivity, viscosity, proton, and anion (conjugate base) self-diffusion coefficients, and Hammett acidity. The highest conductivities, and also the highest viscosities, are observed for the phosphonic and phosphinic acid model compounds. Arrhenius analysis of conductivity and viscosity for these two acids reveals much lower activation energies for ion transport than for viscous flow. Additionally, the proton self-diffusion coefficients are much higher than the conjugate-base self-diffusion coefficients for these two acids. Taken together, these data suggest that anhydrous proton transport in the phosphonic and phosphinic acid model compounds occurs primarily by a structure-diffusion, hopping-based mechanism rather than a vehicle mechanism. Further analysis of ionic conductivity and ion self-diffusion rates by using the Nernst-Einstein equation reveals that the phosphonic and phosphinic acid model compounds are relatively highly dissociated even under anhydrous conditions. In contrast, sulfonic and carboxylic acid-based systems exhibit relatively low degrees of dissociation under anhydrous conditions. These findings suggest that fluoroalkyl phosphonic and phosphinic acids are good candidates for further development as anhydrous, high-temperature proton conductors.

Cyclic voltammetry modeling of proton transport effects on redox charge storage in conductive materials: application to a TiO2 mesoporous film.

PubMed

Kim, Y S; Balland, V; Limoges, B; Costentin, C

2017-07-21

Cyclic voltammetry is a particularly useful tool for characterizing charge accumulation in conductive materials. A simple model is presented to evaluate proton transport effects on charge storage in conductive materials associated with a redox process coupled with proton insertion in the bulk material from an aqueous buffered solution, a situation frequently encountered in metal oxide materials. The interplay between proton transport inside and outside the materials is described using a formulation of the problem through introduction of dimensionless variables that allows defining the minimum number of parameters governing the cyclic voltammetry response with consideration of a simple description of the system geometry. This approach is illustrated by analysis of proton insertion in a mesoporous TiO 2 film.

Molecular basis of proton block of L-type Ca2+ channels.

PubMed

Chen, X H; Bezprozvanny, I; Tsien, R W

1996-11-01

Hydrogen ions are important regulators of ion flux through voltage-gated Ca2+ channels but their site of action has been controversial. To identify molecular determinants of proton block of L-type Ca2+ channels, we combined site-directed mutagenesis and unitary current recordings from wild-type (WT) and mutant L-type Ca2+ channels expressed in Xenopus oocytes. WT channels in 150 mM K+ displayed two conductance states, deprotonated (140 pS) and protonated (45 pS), as found previously in native L-type Ca2+ channels. Proton block was altered in a unique fashion by mutation of each of the four P-region glutamates (EI-EIV) that form the locus of high affinity Ca2+ interaction. Glu(E)-->Gln(Q) substitution in either repeats I or III abolished the high-conductance state, as if the titration site had become permanently protonated. While the EIQ mutant displayed only an approximately 40 pS conductance, the EIIIQ mutant showed the approximately 40 pS conductance plus additional pH-sensitive transitions to an even lower conductance level. The EIVQ mutant exhibited the same deprotonated and protonated conductance states as WT, but with an accelerated rate of deprotonation. The EIIQ mutant was unusual in exhibiting three conductance states (approximately 145, 102, 50 pS, respectively). Occupancy of the low conductance state increased with external acidification, albeit much higher proton concentration was required than for WT. In contrast, the equilibrium between medium and high conductance levels was apparently pH-insensitive. We concluded that the protonation site in L-type Ca2+ channels lies within the pore and is formed by a combination of conserved P-region glutamates in repeats I, II, and III, acting in concert. EIV lies to the cytoplasmic side of the site but exerts an additional stabilizing influence on protonation, most likely via electrostatic interaction. These findings are likely to hold for all voltage-gated Ca2+ channels and provide a simple molecular explanation for the modulatory effect of H+ ions on open channel flux and the competition between H+ ions and permeant divalent cations. The characteristics of H+ interactions advanced our picture of the functional interplay between P-region glutamates, with important implications for the mechanism of Ca2+ selectivity and permeation.

Proton Testing of nVidia GTX 1050 GPU

NASA Technical Reports Server (NTRS)

Wyrwas, E. J.

2017-01-01

Single-Event Effects (SEE) testing was conducted on the nVidia GTX 1050 Graphics Processor Unit (GPU); herein referred to as device under test (DUT). Testing was conducted at Massachusetts General Hospitals (MGH) Francis H. Burr Proton Therapy Center on April 9th, 2017 using 200-MeV protons. This testing trip was purposed to provide a baseline assessment of the radiation susceptibility of the DUT as no previous testing had been conducted on this component.

Proton Testing of nVidia Jetson TX1

NASA Technical Reports Server (NTRS)

Wyrwas, Edward J.

2017-01-01

Single-Event Effects (SEE) testing was conducted on the nVidia Jetson TX1 System on Chip (SOC); herein referred to as device under test (DUT). Testing was conducted at Massachusetts General Hospitals (MGH) Francis H. Burr Proton Therapy Center on October 16th, 2016 using 200MeV protons. This testing trip was purposed to provide a baseline assessment of the radiation susceptibility of the DUT as no previous testing had been conducted on this component.

Proton trapping in yttrium-doped barium zirconate

NASA Astrophysics Data System (ADS)

Yamazaki, Yoshihiro; Blanc, Frédéric; Okuyama, Yuji; Buannic, Lucienne; Lucio-Vega, Juan C.; Grey, Clare P.; Haile, Sossina M.

2013-07-01

The environmental benefits of fuel cells have been increasingly appreciated in recent years. Among candidate electrolytes for solid-oxide fuel cells, yttrium-doped barium zirconate has garnered attention because of its high proton conductivity, particularly in the intermediate-temperature region targeted for cost-effective solid-oxide fuel cell operation, and its excellent chemical stability. However, fundamental questions surrounding the defect chemistry and macroscopic proton transport mechanism of this material remain, especially in regard to the possible role of proton trapping. Here we show, through a combined thermogravimetric and a.c. impedance study, that macroscopic proton transport in yttrium-doped barium zirconate is limited by proton-dopant association (proton trapping). Protons must overcome the association energy, 29 kJ mol-1, as well as the general activation energy, 16 kJ mol-1, to achieve long-range transport. Proton nuclear magnetic resonance studies show the presence of two types of proton environment above room temperature, reflecting differences in proton-dopant configurations. This insight motivates efforts to identify suitable alternative dopants with reduced association energies as a route to higher conductivities.

Proton trapping in yttrium-doped barium zirconate.

PubMed

Yamazaki, Yoshihiro; Blanc, Frédéric; Okuyama, Yuji; Buannic, Lucienne; Lucio-Vega, Juan C; Grey, Clare P; Haile, Sossina M

2013-07-01

The environmental benefits of fuel cells have been increasingly appreciated in recent years. Among candidate electrolytes for solid-oxide fuel cells, yttrium-doped barium zirconate has garnered attention because of its high proton conductivity, particularly in the intermediate-temperature region targeted for cost-effective solid-oxide fuel cell operation, and its excellent chemical stability. However, fundamental questions surrounding the defect chemistry and macroscopic proton transport mechanism of this material remain, especially in regard to the possible role of proton trapping. Here we show, through a combined thermogravimetric and a.c. impedance study, that macroscopic proton transport in yttrium-doped barium zirconate is limited by proton-dopant association (proton trapping). Protons must overcome the association energy, 29 kJ mol(-1), as well as the general activation energy, 16 kJ mol(-1), to achieve long-range transport. Proton nuclear magnetic resonance studies show the presence of two types of proton environment above room temperature, reflecting differences in proton-dopant configurations. This insight motivates efforts to identify suitable alternative dopants with reduced association energies as a route to higher conductivities.

Towards neat methanol operation of direct methanol fuel cells: a novel self-assembled proton exchange membrane.

PubMed

Li, Jing; Cai, Weiwei; Ma, Liying; Zhang, Yunfeng; Chen, Zhangxian; Cheng, Hansong

2015-04-18

We report here a novel proton exchange membrane with remarkably high methanol-permeation resistivity and excellent proton conductivity enabled by carefully designed self-assembled ionic conductive channels. A direct methanol fuel cell utilizing the membrane performs well with a 20 M methanol solution, very close to the concentration of neat methanol.

Fractal diffusion in high temperature polymer electrolyte fuel cell membranes

NASA Astrophysics Data System (ADS)

Hopfenmüller, Bernhard; Zorn, Reiner; Holderer, Olaf; Ivanova, Oxana; Lehnert, Werner; Lüke, Wiebke; Ehlers, Georg; Jalarvo, Niina; Schneider, Gerald J.; Monkenbusch, Michael; Richter, Dieter

2018-05-01

The performance of fuel cells depends largely on the proton diffusion in the proton conducting membrane, the core of a fuel cell. High temperature polymer electrolyte fuel cells are based on a polymer membrane swollen with phosphoric acid as the electrolyte, where proton conduction takes place. We studied the proton diffusion in such membranes with neutron scattering techniques which are especially sensitive to the proton contribution. Time of flight spectroscopy and backscattering spectroscopy have been combined to cover a broad dynamic range. In order to selectively observe the diffusion of protons potentially contributing to the ion conductivity, two samples were prepared, where in one of the samples the phosphoric acid was used with hydrogen replaced by deuterium. The scattering data from the two samples were subtracted in a suitable way after measurement. Thereby subdiffusive behavior of the proton diffusion has been observed and interpreted in terms of a model of fractal diffusion. For this purpose, a scattering function for fractal diffusion has been developed. The fractal diffusion dimension dw and the Hausdorff dimension df have been determined on the length scales covered in the neutron scattering experiments.

Proton Conduction in Grain-Boundary-Free Oxygen-Deficient BaFeO2.5+δ Thin Films

PubMed Central

Benes, Alexander; Molinari, Alan; Kruk, Robert; Brötz, Joachim; Chellali, Reda; Hahn, Horst

2017-01-01

Reduction of the operating temperature to an intermediate temperature range between 350 °C and 600 °C is a necessity for Solid Oxide Fuel/Electrolysis Cells (SOFC/SOECs). In this respect the application of proton-conducting oxides has become a broad area of research. Materials that can conduct protons and electrons at the same time, to be used as electrode catalysts on the air electrode, are especially rare. In this article we report on the proton conduction in expitaxially grown BaFeO2.5+δ (BFO) thin films deposited by pulsed laser deposition on Nb:SrTiO3 substrates. By using Electrochemical Impedance Spectroscopy (EIS) measurements under different wet and dry atmospheres, the bulk proton conductivity of BFO (between 200 °C and 300 °C) could be estimated for the first time (3.6 × 10−6 S cm−1 at 300 °C). The influence of oxidizing measurement atmosphere and hydration revealed a strong dependence of the conductivity, most notably at temperatures above 300 °C, which is in good agreement with the hydration behavior of BaFeO2.5 reported previously. PMID:29286321

NMR detection of pH-dependent histidine-water proton exchange reveals the conduction mechanism of a transmembrane proton channel.

PubMed

Hu, Fanghao; Schmidt-Rohr, Klaus; Hong, Mei

2012-02-29

The acid-activated proton channel formed by the influenza M2 protein is important for the life cycle of the virus. A single histidine, His37, in the M2 transmembrane domain (M2TM) is responsible for pH activation and proton selectivity of the channel. Recent studies suggested three models for how His37 mediates proton transport: a shuttle mechanism involving His37 protonation and deprotonation, a H-bonded imidazole-imidazolium dimer model, and a transporter model involving large protein conformational changes in synchrony with proton conduction. Using magic-angle-spinning (MAS) solid-state NMR spectroscopy, we examined the proton exchange and backbone conformational dynamics of M2TM in a virus-envelope-mimetic membrane. At physiological temperature and pH, (15)N NMR spectra show fast exchange of the imidazole (15)N between protonated and unprotonated states. To quantify the proton exchange rates, we measured the (15)N T(2) relaxation times and simulated them for chemical-shift exchange and fluctuating N-H dipolar fields under (1)H decoupling and MAS. The exchange rate is 4.5 × 10(5) s(-1) for Nδ1 and 1.0 × 10(5) s(-1) for Nε2, which are approximately synchronized with the recently reported imidazole reorientation. Binding of the antiviral drug amantadine suppressed both proton exchange and ring motion, thus interfering with the proton transfer mechanism. By measuring the relative concentrations of neutral and cationic His as a function of pH, we determined the four pK(a) values of the His37 tetrad in the viral membrane. Fitting the proton current curve using the charge-state populations from these pK(a)'s, we obtained the relative conductance of the five charge states, which showed that the +3 channel has the highest time-averaged unitary conductance. At physiologically relevant pH, 2D correlation spectra indicated that the neutral and cationic histidines do not have close contacts, ruling out the H-bonded dimer model. Moreover, a narrowly distributed nonideal helical structure coexists with a broadly distributed ideal helical conformation without interchange on the sub-10 ms time scale, thus excluding the transporter model in the viral membrane. These data support the shuttle mechanism of proton conduction, whose essential steps involve His-water proton exchange facilitated by imidazole ring reorientations. © 2011 American Chemical Society

The State of Water in Proton Conducting Membranes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Allcock, Harry R.; Benesi, Alan; Macdonald, Digby D.

2010-08-27

The research carried out under grant No. DE-FG02-07ER46371, "The State of Water in Proton Conducting Membranes", during the period June 1, 2008 - May 31, 2010 was comprised of three related parts. These are: 1. An examination of the state of water in classical proton conduction membranes with the use of deuterium T1 NMR spectroscopy (Allcock and Benesi groups). 2. A dielectric relaxation examination of the behavior of water in classical ionomer membranes (Macdonald program). 3. Attempts to synthesize new proton-conduction polymers and membranes derived from the polyphosphazene system. (Allcock program) All three are closely related, crucial aspects of themore » design and development of new and improved polymer electrolyte fuel cell membranes on which the future of fuel cell technology for portable applications depends.« less

Effect of glycidyl methacrylate (GMA) incorporation on water uptake and conductivity of proton exchange membranes

NASA Astrophysics Data System (ADS)

Sproll, Véronique; Schmidt, Thomas J.; Gubler, Lorenz

2018-03-01

The aim of this work was to investigate how hygroscopic moieties like hydrolyzed glycidyl methacrylate (GMA) influence the properties of sulfonated polysytrene based proton exchange membranes (PEM). Therefore, several membranes were synthesized by electron beam treatment of the ETFE (ethylene-alt-tetrafluoroethylene) base film with a subsequent co-grafting of styrene and GMA at different ratios. The obtained membranes were sulfonated to introduce proton conducting groups and the epoxide moiety of the GMA unit was hydrolyzed for a better water absorption. The PEM was investigated regarding its structural composition, water uptake and through-plane conductivity. It could be shown that the density of sulfonic acid groups has a higher influence on the proton conductivity of the PEM than an increased water uptake.

Proton-conducting ionic liquid-based Proton Exchange Membrane Fuel Cell membranes: The key role of ionomer-ionic liquid interaction

NASA Astrophysics Data System (ADS)

Martinez, Mathieu; Molmeret, Yannick; Cointeaux, Laure; Iojoiu, Cristina; Leprêtre, Jean-Claude; El Kissi, Nadia; Judeinstein, Patrick; Sanchez, Jean-Yves

The paper deals with the synthesis and characterisation of proton-conducting ionic liquids (PCILs) and their polymer electrolytes obtained by blending modified Nafion membranes with different concentrations of PCILs. The PCILs are obtained by the neutralization of triethylamine with different organic acids. The first part of the paper studies the influence of acidity and acid structure on PCIL thermal and electrochemical performance, while the second part examines membrane conductivity and reveals it to depend more on PCIL structure than on its intrinsic conductivity. At 130 °C, conductivities exceeding 10 mS cm -1 were obtained in fully anhydrous conditions.

Electrode assembly for use in a solid polymer electrolyte fuel cell

DOEpatents

Raistrick, Ian D.

1989-01-01

A gas reaction fuel cell may be provided with a solid polymer electrolyte membrane. Porous gas diffusion electrodes are formed of carbon particles supporting a catalyst which is effective to enhance the gas reactions. The carbon particles define interstitial spaces exposing the catalyst on a large surface area of the carbon particles. A proton conducting material, such as a perfluorocarbon copolymer or ruthenium dioxide contacts the surface areas of the carbon particles adjacent the interstitial spaces. The proton conducting material enables protons produced by the gas reactions adjacent the supported catalyst to have a conductive path with the electrolyte membrane. The carbon particles provide a conductive path for electrons. A suitable electrode may be formed by dispersing a solution containing a proton conducting material over the surface of the electrode in a manner effective to coat carbon surfaces adjacent the interstitial spaces without impeding gas flow into the interstitial spaces.

Synthesis and high proton conductive performance of a quaternary vanadomolybdotungstosilicic heteropoly acid.

PubMed

Cai, Huaxue; Wu, Xuefei; Wu, Qingyin; Yan, Wenfu

2016-09-28

A new vanadium and molybdenum-substituted quaternary silicon-containing heteropoly acid H6SiW9MoV2O40·15H2O has been synthesized in this paper by the stepwise acidification and the stepwise addition of elemental solutions. The structural feature and hydration of this product were characterized by IR, UV, XRD and TG-DTA, and its proton conductivity was measured by electrochemical impedance spectroscopy (EIS). The result of EIS shows that H6SiW9MoV2O40·15H2O is a solid high-proton conductor with a conductivity of 6.01 × 10(-3) S cm(-1) at 22 °C and 80% relative humidity, which increases at higher temperatures. Its conductive activation energy is 27.5 kJ mol(-1), which suggests that the mechanism of proton conduction is dominated by the vehicle mechanism.

High proton conductivity in the molecular interlayer of a polymer nanosheet multilayer film.

PubMed

Sato, Takuma; Hayasaka, Yuta; Mitsuishi, Masaya; Miyashita, Tokuji; Nagano, Shusaku; Matsui, Jun

2015-05-12

High proton conductivity was achieved in a polymer multilayer film with a well-defined two-dimensional lamella structure. The multilayer film was prepared by deposition of poly(N-dodecylacryamide-co-acrylic acid) (p(DDA/AA)) monolayers onto a solid substrate using the Langmuir-Blodgett technique. Grazing-angle incidence X-ray diffraction measurement of a 30-layer film of p(DDA/AA) showed strong diffraction peaks in the out-of-plane direction at 2θ = 2.26° and 4.50°, revealing that the multilayer film had a highly uniform layered structure with a monolayer thickness of 2.0 nm. The proton conductivity of the p(DDA/AA) multilayer film parallel to the layer plane direction was 0.051 S/cm at 60 °C and 98% relative humidity with a low activation energy of 0.35 eV, which is comparable to perfluorosulfonic acid membranes. The high conductivity and low activation energy resulted from the formation of uniform two-dimensional proton-conductive nanochannels in the hydrophilic regions of the multilayer film. The proton conductivity of the multilayer film perpendicular to the layer plane was determined to be 2.1 × 10(-13) S/cm. Therefore, the multilayer film showed large anisotropic conductivity with an anisotropic ratio of 2.4 × 10(11).

Structure and conductivity of epitaxial thin films of barium ferrite and its hydrated form BaFeO2.5-x+δ (OH)2x

NASA Astrophysics Data System (ADS)

Anitha Sukkurji, Parvathy; Molinari, Alan; Benes, Alexander; Loho, Christoph; Sai Kiran Chakravadhanula, Venkata; Garlapati, Suresh Kumar; Kruk, Robert; Clemens, Oliver

2017-03-01

Barium ferrite and its hydrated form (BaFeO2.5-x+δ (OH)2x , BFO) is an interesting cathode material for protonic ceramic fuel cells (PCFC) due to its potential to be both, conducting for electrons and protons. We report on the fabrication of almost epitaxially grown thin films (22 nm) of barium ferrite BaFeO~2.5 (BFO) on Nb-doped SrTiO3 substrates via pulsed laser deposition (PLD), followed by treatment under inert, and subsequently wet inert atmospheres to induce water (respectively proton) incorporation. Microstructure, chemical composition and conducting properties are investigated for the BFO films and their hydrated forms, highlighting the influence of hydration on the conductivity characteristics between ~200-290 K. We find that water incorporation gives a strong enhancement of the conductivity to ~10-9 S cm-1 compared to argon annealed films, inducing electronic and protonic charge carriers at the same time. In comparison to bulk powders, proton conductivity is found to be strongly suppressed in such thin hydrated BFO films, pointing towards the influence of strain on the conductivity, which is evaluated based on a detailed investigation by high-resolution transmission electron microscopy.

Flexible Proton-Gated Oxide Synaptic Transistors on Si Membrane.

PubMed

Zhu, Li Qiang; Wan, Chang Jin; Gao, Ping Qi; Liu, Yang Hui; Xiao, Hui; Ye, Ji Chun; Wan, Qing

2016-08-24

Ion-conducting materials have received considerable attention for their applications in fuel cells, electrochemical devices, and sensors. Here, flexible indium zinc oxide (InZnO) synaptic transistors with multiple presynaptic inputs gated by proton-conducting phosphorosilicate glass-based electrolyte films are fabricated on ultrathin Si membranes. Transient characteristics of the proton gated InZnO synaptic transistors are investigated, indicating stable proton-gating behaviors. Short-term synaptic plasticities are mimicked on the proposed proton-gated synaptic transistors. Furthermore, synaptic integration regulations are mimicked on the proposed synaptic transistor networks. Spiking logic modulations are realized based on the transition between superlinear and sublinear synaptic integration. The multigates coupled flexible proton-gated oxide synaptic transistors may be interesting for neuroinspired platforms with sophisticated spatiotemporal information processing.

H+-type and OH--type biological protonic semiconductors and complementary devices

NASA Astrophysics Data System (ADS)

Deng, Yingxin; Josberger, Erik; Jin, Jungho; Rousdari, Anita Fadavi; Helms, Brett A.; Zhong, Chao; Anantram, M. P.; Rolandi, Marco

2013-10-01

Proton conduction is essential in biological systems. Oxidative phosphorylation in mitochondria, proton pumping in bacteriorhodopsin, and uncoupling membrane potentials by the antibiotic Gramicidin are examples. In these systems, H+ hop along chains of hydrogen bonds between water molecules and hydrophilic residues - proton wires. These wires also support the transport of OH- as proton holes. Discriminating between H+ and OH- transport has been elusive. Here, H+ and OH- transport is achieved in polysaccharide- based proton wires and devices. A H+- OH- junction with rectifying behaviour and H+-type and OH--type complementary field effect transistors are demonstrated. We describe these devices with a model that relates H+ and OH- to electron and hole transport in semiconductors. In turn, the model developed for these devices may provide additional insights into proton conduction in biological systems.

H+-type and OH−-type biological protonic semiconductors and complementary devices

PubMed Central

Deng, Yingxin; Josberger, Erik; Jin, Jungho; Rousdari, Anita Fadavi; Helms, Brett A.; Zhong, Chao; Anantram, M. P.; Rolandi, Marco

2013-01-01

Proton conduction is essential in biological systems. Oxidative phosphorylation in mitochondria, proton pumping in bacteriorhodopsin, and uncoupling membrane potentials by the antibiotic Gramicidin are examples. In these systems, H+ hop along chains of hydrogen bonds between water molecules and hydrophilic residues – proton wires. These wires also support the transport of OH− as proton holes. Discriminating between H+ and OH− transport has been elusive. Here, H+ and OH− transport is achieved in polysaccharide- based proton wires and devices. A H+- OH− junction with rectifying behaviour and H+-type and OH−-type complementary field effect transistors are demonstrated. We describe these devices with a model that relates H+ and OH− to electron and hole transport in semiconductors. In turn, the model developed for these devices may provide additional insights into proton conduction in biological systems. PMID:24089083

Temperature dependence of partial conductivities of the BaZr0.7Ce0.2Y0.1O3-δ proton conductor

NASA Astrophysics Data System (ADS)

Heras-Juaristi, Gemma; Pérez-Coll, Domingo; Mather, Glenn C.

2017-10-01

Partial conductivities are presented for BaZr0.7Ce0.2Y0.1O3-δ, an important proton conductor for protonic-ceramic fuel cells and membrane reactors. Atmospheric dependencies of impedance performed in humidified and dry O2, air, N2 and H2(10%)/N2(90%) in the temperature range 300-900 °C, supported by the modified emf method, confirm significant electron-hole and protonic contributions to transport. For very reducing and wet atmospheres, the conductivity is predominantly ionic, with a higher participation of protons with decreasing temperature and increasing water-vapour partial pressure (pH2O). From moderately reducing conditions of wet N2 to wet O2, however, the conductivity is considerably influenced by electron holes as revealed by a significant dependence of total conductivity on oxygen partial pressure (pO2). With higher pH2O, proton transport increases, with a concomitant decrease of holes and oxygen vacancies. However, the effect of pH2O is also influenced by temperature, with a greater protonic contribution at both lower temperature and pO2. Values of proton transport number tH ≈ 0.63 and electronic transport number th ≈ 0.37 are obtained at 600 °C for pH2O = 0.022 atm and pO2 = 0.2 atm, whereas tH ≈ 0.95 and th ≈ 0.05 for pO2 = 10-5 atm. A hydration enthalpy of -109 kJ mol-1 is obtained in the range 600-900 °C.

Standing shocks in a two-fluid solar wind

NASA Technical Reports Server (NTRS)

Habbal, Shadia R.; Hu, You Qiu; Esser, Ruth

1994-01-01

We present a numerical study of the formation of standing shocks in the solar wind using a two-fluid time-dependent model in the presence of Alfven waves. Included in this model is the adiabatic cooling and thermal conduction of both electrons and protons. In this study, standing shocks develop in the flow when additional critical points form as a result of either localized momentum addition or rapid expansion of the flow tube below the existing sonic point. While the flow speed and density exhibit the same characteristics as found in earlier studies of the formation of standing shocks, the inclusion of electron and proton heat conduction produces different signatures in the electron and proton temperature profiles across the shock layer. Owing to the strong heat conduction, the electron temperature is nearly continuous across the shock, but its gradient has a negative jump across it, thus producing a net heat flux out of the shock layer. The proton temperature exhibits the same characteristics for shocks produced by momentum addition but behaves differently when the shock is formed by the rapid divergence of the flow tube. The adiabatic cooling in a rapidly diverging flow tube reduces the proton temperature so substantially that the proton heat conduction becomes negligible in the vicinity of the shock. As a result, protons experience a positive jump in temperature across the shock. While Alfven waves do not affect the formation of standing shocks, they contribute to the change of the mmomentum and energy balance across them. We also find that for this solar wind model the inclusion of thermal conduction and adiabatic cooling for the elctrons and protons increases significantly the range of parameters characterizing the formation of standing shocks over those previously found for isothermal and polytropic models.

Proton Content and Nature in Perovskite Ceramic Membranes for Medium Temperature Fuel Cells and Electrolysers

PubMed Central

Colomban, Philippe; Zaafrani, Oumaya; Slodczyk, Aneta

2012-01-01

Recent interest in environmentally friendly technology has promoted research on green house gas-free devices such as water steam electrolyzers, fuel cells and CO2/syngas converters. In such applications, proton conducting perovskite ceramics appear especially promising as electrolyte membranes. Prior to a successful industrial application, it is necessary to determine/understand their complex physical and chemical behavior, especially that related to proton incorporation mechanism, content and nature of bulk protonic species. Based on the results of quasi-elastic neutron scattering (QNS), thermogravimetric analysis (TGA), Raman and IR measurements we will show the complexity of the protonation process and the importance of differentiation between the protonic species adsorbed on a membrane surface and the bulk protons. The bulk proton content is very low, with a doping limit (~1–5 × 10−3 mole/mole), but sufficient to guarantee proton conduction below 600 °C. The bulk protons posses an ionic, covalent bond free nature and may occupy an interstitial site in the host perovskite structure. PMID:24958293

Development of a tritium monitor combined with an electrochemical tritium pump using a proton conducting oxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanaka, M.; Sugiyama, T.

2015-03-15

The detection of low level tritium is one of the key issues for tritium management in tritium handling facilities. Such a detection can be performed by tritium monitors based on proton conducting oxide technique. We tested a tritium monitoring system composed of a commercial proportional counter combined with an electrochemical hydrogen pump equipped with CaZr{sub 0.9}In{sub 0.1}O{sub 3-α} as proton conducting oxide. The hydrogen pump operated at 973 K under electrolysis conditions using tritiated water vapor (HTO). The proton conducting oxide extracts tritium molecules (HT) from HTO and tritium concentration is measured by the proportional counter. The advantage of themore » proposed tritium monitoring system is that it is able to convert HTO into molecular hydrogen.« less

Better Proton-Conducting Polymers for Fuel-Cell Membranes

NASA Technical Reports Server (NTRS)

Narayan, Sri; Reddy, Prakash

2012-01-01

Polyoxyphenylene triazole sulfonic acid has been proposed as a basis for development of improved proton-conducting polymeric materials for solid-electrolyte membranes in hydrogen/air fuel cells. Heretofore, the proton-conducting membrane materials of choice have been exemplified by a family of perfluorosulfonic acid-based polymers (Nafion7 or equivalent). These materials are suitable for operation in the temperature of 75 to 85 C, but in order to reduce the sizes and/or increase the energy-conversion efficiencies of fuel-cell systems, it would be desirable to increase temperatures to as high as 120 C for transportation applications, and to as high as 180 C for stationary applications. However, at 120 C and at relative humidity values below 50 percent, the loss of water from perfluorosulfonic acid-based polymer membranes results in fuel-cell power densities too low to be of practical value. Therefore, membrane electrolyte materials that have usefully high proton conductivity in the temperature range of 180 C at low relative humidity and that do not rely on water for proton conduction at 180 C would be desirable. The proposed polyoxyphenylene triazole sulfonic acid-based materials have been conjectured to have these desirable properties. These materials would be free of volatile or mobile acid constituents. The generic molecular structure of these materials is intended to exploit the fact, demonstrated in previous research, that materials that contain ionizable acid and base groups covalently attached to thermally stable polymer backbones exhibit proton conduction even in the anhydrous state.

Considerations of the Effects of Naphthalene Moieties on the Design of Proton-Conductive Poly(arylene ether ketone) Membranes for Direct Methanol Fuel Cells.

PubMed

Wang, Baolong; Hong, Lihua; Li, Yunfeng; Zhao, Liang; Wei, Yuxue; Zhao, Chengji; Na, Hui

2016-09-14

Novel sulfonated poly(arylene ether ketones) (SDN-PAEK-x), consisting of dual naphthalene and flexible sulfoalkyl groups, were prepared via polycondensation, demethylation, and sulfobutylation grafting reaction. Among them, SDN-PAEK-1.94 membrane with the highest ion exchange capacity (IEC = 2.46 mequiv·g(-1)) exhibited the highest proton conductivity, which was 0.147 S· cm(-1) at 25 °C and 0.271 S·cm(-1) at 80 °C, respectively. The introduction of dual naphthalene moieties is expected to achieve much enhanced properties compared to those of sulfonated poly(arylene ether ketones) (SNPAEK-x), consisting of single naphthalene and flexible sulfoalkyl groups. Compared with SNPAEK-1.60 with a similar IEC, SDN-PAEK-1.74 membrane showed higher proton conductivity, higher IEC normalized conductivity, and higher effective proton mobility, although it had lower analytical acid concentration. The SDN-PAEK-x membranes with IECs higher than 1.96 mequiv·g(-1) also exhibited higher proton conductivity than that of recast Nafion membrane. Furthermore, SDN-PAEK-1.94 displayed a better single cell performance with a maximum power density of 60 mW·cm(-2) at 80 °C. Considering its high proton conductivity, excellent single cell performance, good mechanical stabilities, low membrane swelling, and methanol permeability, SDN-PAEK-x membranes are promising candidates as alternative polymer electrolyte membranes to Nafion for direct methanol fuel cell applications.

Proton conduction in electrolyte made of manganese dioxide for hydrogen gas sensor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koyanaka, Hideki; Ueda, Yoshikatsu; Takeuchi, K

2012-01-01

We propose a network model of oxygen-pairs to store and conduct protons on the surface of manganese dioxide with a weak covalent bond like protons stored in pressured ice. The atomic distances of oxygen-pairs were estimated between 2.57 and 2.60 angstroms in crystal structures of ramsdellite-type and lambda-type manganese dioxides by using protonated samples and inelastic neutron scattering measurements. Good properties for a hydrogen gas sensor using electrolytes made of manganese dioxides that contain such oxygen-pairs were confirmed experimentally.

Polymerized Paired Ions as Polymeric Ionic Liquid-Proton Conductivity.

PubMed

Gu, Hong; Yan, Feng; Texter, John

2016-07-01

A new polymerized ionic liquid has been derived by photopolymerization of a stimuli-responsive ionic liquid surfactant, ILAMPS, which is composed of polymerizable, paired ions. The cation is 1-methyl-3-[11-(acryloyloxy)undecyl] imidazolium (IL), and the anion is 2-acrylamido-2-methyl-1-propanesulfonate (AMPS). This ion combination is a new ionic liquid. The resulting hygroscopic resins are highly polarizable, suitable for sensor design and for ultracapacitor fabrication and proton conducting. Interactions of imidazolium with anions provide basis for stimuli-responsiveness, and are used to promote proton transport. Doping with one equivalent of HPF6 at 0% relative humidity produces a 100-fold increase in proton conductivity at 100-125 °C and activation energies for proton transport lower than those of Nafion at water loadings less than 5 per sulfonate. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Two different types of channels exhibiting distinct proton transport behavior in an open-framework aluminophosphate

NASA Astrophysics Data System (ADS)

Xue, Chen; Zou, Yang; Liu, Shao-Xian; Ren, Xiao-Ming; Tian, Zheng-Fang

2018-02-01

A three-dimensional open-framework aluminophosphate, (NH4)2Al4(PO4)4(HPO4)·H2O (1), shows two types of eight-membered polyhedral ring channels. The lattice water molecules occupy within the channel with (HO)PO3 tetrahedra (channel-I), whilst the ammonium ions reside in another type of channel (channel-II). This aluminophosphate shows superior stability to water and NaOH aqueous solution, but unstable to H2SO4 aqueous solution. The proton conductance of 1 has been investigated under anhydrous condition and various relative humidity, indicating rather low conductivity under anhydrous condition even at elevated temperature (σdc = 9.05 × 10-13 S cm-1 at 343 K and 4.25 × 10-10 S cm-1 even at 473 K), and this situation demonstrates that both the ammonium ions and the protons in (HO)PO3 tetrahedra have quite low mobility. The conductivity of 1 reaches to 4.0 × 10-5 S cm-1 at 299 K, 2.57 × 10-4 S cm-1 at 343 K under 99%RH, respectively. The greatly enhancement of proton conductivity at 99%RH is due to the formation of H-bond between H2O molecules and (HO)PO3 tetrahedra in the channel-I to assist proton hopping process, while the ammonium ions show negligible contribution to enhancement of proton conductivity.

Preparation of nano-structured polymeric proton conducting membranes for use in fuel cells.

PubMed

Alberti, Giulio; Casciola, Mario; Pica, Monica; Di Cesare, Giusi

2003-03-01

We briefly discuss the state of the art of polymer electrolyte membrane fuel cells and suggest that the main obstacles to the commercial development of these fuel cells are essentially the high costs and poor characteristics of present proton conducting membranes. A strategy for the preparation of improved nanocomposite membranes based on the introduction of proton conducting lamell? in the polymeric matrix of present ionomeric membranes is then discussed. Due to their high proton conductivity (in some cases even higher than 10(-1) S cm(-1)), tailor made lamellae obtained by exfoliation of superacid metal (IV) phosphonates are particularly suitable for the preparation of these hybrid membranes. The expected positive influence of the dispersed lamellae on important properties of proton conducting membranes, such as swelling, mechanical resistance, proton transport, and diffusion of methanol, are also discussed. The methods used to obtain good lamellar dispersions into ionomeric polymers and the preparation and main characteristics of some hybrid membranes are also briefly described. The presence of nanoparticles of metal phosphonates in the electrodic interfaces Nafion/Pt already considerably improves the electrochemical characteristics of fuel cells in the temperature range 80-130 degrees C. The increased working temperature of the fuel cell considerably reduces CO poisoning of the platinum electrodes and allows better control of the cooling system, thus overcoming important obstacles to the development of medium temperature PEM fuel cells.

Fractal diffusion in high temperature polymer electrolyte fuel cell membranes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hopfenmuller, Bernhard; Zorn, Reiner; Holderer, Olaf

In this paper, the performance of fuel cells depends largely on the proton diffusion in the proton conducting membrane, the core of a fuel cell. High temperature polymer electrolyte fuel cells are based on a polymer membrane swollen with phosphoric acid as the electrolyte, where proton conduction takes place. We studied the proton diffusion in such membranes with neutron scattering techniques which are especially sensitive to the proton contribution. Time of flight spectroscopy and backscattering spectroscopy have been combined to cover a broad dynamic range. In order to selectively observe the diffusion of protons potentially contributing to the ion conductivity,more » two samples were prepared, where in one of the samples the phosphoric acid was used with hydrogen replaced by deuterium. The scattering data from the two samples were subtracted in a suitable way after measurement. Thereby subdiffusive behavior of the proton diffusion has been observed and interpreted in terms of a model of fractal diffusion. For this purpose, a scattering function for fractal diffusion has been developed. The fractal diffusion dimension d w and the Hausdorff dimension d f have been determined on the length scales covered in the neutron scattering experiments.« less

Fractal diffusion in high temperature polymer electrolyte fuel cell membranes

DOE PAGES

Hopfenmuller, Bernhard; Zorn, Reiner; Holderer, Olaf; ...

2018-05-29

In this paper, the performance of fuel cells depends largely on the proton diffusion in the proton conducting membrane, the core of a fuel cell. High temperature polymer electrolyte fuel cells are based on a polymer membrane swollen with phosphoric acid as the electrolyte, where proton conduction takes place. We studied the proton diffusion in such membranes with neutron scattering techniques which are especially sensitive to the proton contribution. Time of flight spectroscopy and backscattering spectroscopy have been combined to cover a broad dynamic range. In order to selectively observe the diffusion of protons potentially contributing to the ion conductivity,more » two samples were prepared, where in one of the samples the phosphoric acid was used with hydrogen replaced by deuterium. The scattering data from the two samples were subtracted in a suitable way after measurement. Thereby subdiffusive behavior of the proton diffusion has been observed and interpreted in terms of a model of fractal diffusion. For this purpose, a scattering function for fractal diffusion has been developed. The fractal diffusion dimension d w and the Hausdorff dimension d f have been determined on the length scales covered in the neutron scattering experiments.« less

Superprotonic conduction through one-dimensional ordered alkali metal ion chains in a lanthanide-organic framework

DOE PAGES

Wang, Xia; Wang, Yanlong; Silver, Mark A.; ...

2018-01-01

An ultrahigh proton conductivity of 2.91 × 10 −2 S cm −1 and an ultralow activation energy of 0.10 eV were observed in an anionic lanthanide-organic framework. Both values approach the records for proton-conducting MOF materials.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Xia; Wang, Yanlong; Silver, Mark A.

An ultrahigh proton conductivity of 2.91 × 10 −2 S cm −1 and an ultralow activation energy of 0.10 eV were observed in an anionic lanthanide-organic framework. Both values approach the records for proton-conducting MOF materials.

Correlating Humidity-Dependent Ionically Conductive Surface Area with Transport Phenomena in Proton-Exchange Membranes

DOE Office of Scientific and Technical Information (OSTI.GOV)

He, Qinggang; Kusoglu, Ahmet; Lucas, Ivan T.

2011-08-01

The objective of this effort was to correlate the local surface ionic conductance of a Nafion? 212 proton-exchange membrane with its bulk and interfacial transport properties as a function of water content. Both macroscopic and microscopic proton conductivities were investigated at different relative humidity levels, using electrochemical impedance spectroscopy and current-sensing atomic force microscopy (CSAFM). We were able to identify small ion-conducting domains that grew with humidity at the surface of the membrane. Numerical analysis of the surface ionic conductance images recorded at various relative humidity levels helped determine the fractional area of ion-conducting active sites. A simple square-root relationshipmore » between the fractional conducting area and observed interfacial mass-transport resistance was established. Furthermore, the relationship between the bulk ionic conductivity and surface ionic conductance pattern of the Nafion? membrane was examined.« less

Preparation and characterization of self-crosslinked organic/inorganic proton exchange membranes

NASA Astrophysics Data System (ADS)

Zhong, Shuangling; Cui, Xuejun; Dou, Sen; Liu, Wencong

A series of silicon-containing sulfonated polystyrene/acrylate (Si-sPS/A) nanoparticles are successfully synthesized via simple emulsion polymerization method. The Si-sPS/A latexes show good film-forming capability and the self-crosslinked organic/inorganic proton exchange membranes are prepared by pouring the Si-sPS/A nanoparticle latexes into glass plates and drying at 60 °C for 10 h and 120 °C for 2 h. The potential of the membranes in direct methanol fuel cells (DMFCs) is characterized preliminarily by studying their thermal stability, ion-exchange capacity, water uptake, methanol diffusion coefficient, proton conductivity and selectivity (proton conductivity/methanol diffusion coefficient). The results indicate that these membranes possess excellent thermal stability and methanol barrier due to the existence of self-crosslinked silica network. In addition, the proton conductivity of the membranes is in the range of 10 -3-10 -2 S cm -1 and all the membranes show much higher selectivity in comparison with Nafion ® 117. These results suggest that the self-crosslinked organic/inorganic proton exchange membranes are particularly promising in DMFC applications.

Self-Healing Proton-Exchange Membranes Composed of Nafion-Poly(vinyl alcohol) Complexes for Durable Direct Methanol Fuel Cells.

PubMed

Li, Yixuan; Liang, Liang; Liu, Changpeng; Li, Yang; Xing, Wei; Sun, Junqi

2018-04-30

Proton-exchange membranes (PEMs) that can heal mechanical damage to restore original functions are important for the fabrication of durable and reliable direct methanol fuel cells (DMFCs). The fabrication of healable PEMs that exhibit satisfactory mechanical stability, enhanced proton conductivity, and suppressed methanol permeability via hydrogen-bonding complexation between Nafion and poly(vinyl alcohol) (PVA) followed by postmodification with 4-carboxybenzaldehyde (CBA) molecules is presented. Compared with pure Nafion, the CBA/Nafion-PVA membranes exhibit enhanced mechanical properties with an ultimate tensile strength of ≈20.3 MPa and strain of ≈380%. The CBA/Nafion-PVA membrane shows a proton conductivity of 0.11 S cm -1 at 80 °C, which is 1.2-fold higher than that of a Nafion membrane. The incorporated PVA gives the CBA/Nafion-PVA membranes excellent proton conductivity and methanol resistance. The resulting CBA/Nafion-PVA membranes are capable of healing mechanical damage of several tens of micrometers in size and restoring their original proton conductivity and methanol resistance under the working conditions of DMFCs. The healing property originates from the reversibility of hydrogen-bonding interactions between Nafion and CBA-modified PVA and the high chain mobility of Nafion and CBA-modified PVA. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Advanced Proton Conducting Polymer Electrolytes for Electrochemical Capacitors

NASA Astrophysics Data System (ADS)

Gao, Han

Research on solid electrochemical energy storage devices aims to provide high performance, low cost, and safe operation solutions for emerging applications from flexible consumer electronics to microelectronics. Polymer electrolytes, minimizing device sealing and liquid electrolyte leakage, are key enablers for these next-generation technologies. In this thesis, a novel proton-conducing polymer electrolyte system has been developed using heteropolyacids (HPAs) and polyvinyl alcohol for electrochemical capacitors. A thorough understanding of proton conduction mechanisms of HPAs together with the interactions among HPAs, additives, and polymer framework has been developed. Structure and chemical bonding of the electrolytes have been studied extensively to identify and elucidate key attributes affecting the electrolyte properties. Numerical models describing the proton conduction mechanism have been applied to differentiate those attributes. The performance optimization of the polymer electrolytes through additives, polymer structural modifications, and synthesis of alternative HPAs has achieved several important milestones, including: (a) high proton mobility and proton density; (b) good ion accessibility at electrode/electrolyte interface; (c) wide electrochemical stability window; and (d) good environmental stability. Specifically, high proton mobility has been addressed by cross-linking the polymer framework to improve the water storage capability at normal-to-high humidity conditions (e.g. 50-80% RH) as well as by incorporating nano-fillers to enhance the water retention at normal humidity levels (e.g. 30-60% RH). High proton density has been reached by utilizing additional proton donors (i.e. acidic plasticizers) and by developing different HPAs. Good ion accessibility has been achieved through addition of plasticizers. Electrochemical stability window of the electrolyte system has also been investigated and expanded by utilizing HPAs with different heteroatoms. The optimized polymer electrolyte demonstrated even higher proton conductivity than pure HPAs and the enabled electrochemical capacitors have demonstrated an exceptionally high rate capability of 50 Vs-1 in cyclic voltammograms and a 10 ms time constant in impedance analyses.

Molecular dynamics calculations suggest a conduction mechanism for the M2 proton channel from influenza A virus

PubMed Central

Khurana, Ekta; Peraro, Matteo Dal; DeVane, Russell; Vemparala, Satyavani; DeGrado, William F.; Klein, Michael L.

2009-01-01

The M2 protein of the influenza A virus is activated by low endosomal pH and performs the essential function of proton transfer into the viral interior. The resulting decrease in pH within the virion is essential for the uncoating and further replication of the viral genetic material. The x-ray crystal [Stouffer AL, et al. (2008) Nature 451:596–599] and solution NMR [Schnell JR, Chou JJ (2008) Nature 451:591–595] structures of the transmembrane region of the M2 homo-tetrameric bundle both revealed pores with narrow constrictions at one end, leaving a question as to how protons enter the channel. His-37, which is essential for proton-gating and selective conduction of protons, lies in the pore of the crystallographic and NMR structures. Here, we explore the different protonation states of the His-37 residues of the M2 bundle in a bilayer using molecular dynamics (MD) simulations. When the His-37 residues are neutral, the protein prefers an Openout-Closedin conformation in which the channel is open to the environment on the outside of the virus but closed to the interior environment of the virus. Diffusion of protons into the channel from the outside of the virus and protonation of His-37 residues in the tetramer stabilizes an oppositely gated Closedout-Openin conformation. Thus, protons might be conducted through a transporter-like mechanism, in which the protein alternates between Openout-Closedin and Closedout-Openin conformations, and His-37 is protonated/deprotonated during each turnover. The transporter-like mechanism is consistent with the known properties of the M2 bundle, including its relatively low rate of proton flux and its strong rectifying behavior. PMID:19144924

Poisoning of Ni-Based anode for proton conducting SOFC by H2S, CO2, and H2O as fuel contaminants

NASA Astrophysics Data System (ADS)

Sun, Shichen; Awadallah, Osama; Cheng, Zhe

2018-02-01

It is well known that conventional solid oxide fuel cells (SOFCs) based on oxide ion conducting electrolyte (e.g., yttria-stabilized zirconia, YSZ) and nickel (Ni) - ceramic cermet anodes are susceptible to poisoning by trace amount of hydrogen sulfide (H2S) while not significantly impacted by the presence of carbon dioxide (CO2) and moisture (H2O) in the fuel stream unless under extreme operating conditions. In comparison, the impacts of H2S, CO2, and H2O on proton-conducting SOFCs remain largely unexplored. This study aims at revealing the poisoning behaviors caused by H2S, CO2, and H2O for proton-conducting SOFCs. Anode-supported proton-conducting SOFCs with BaZe0.1Ce0.7Y0.1Yb0.1O3 (BZCYYb) electrolyte and Ni-BZCYYb anode and La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) cathode as well as Ni-BZCYYb/BZCYYb/Ni-BZCYYb anode symmetrical cells were subjected to low ppm-level H2S or low percentage-level CO2 or H2O in the hydrogen fuel, and the responses in cell electrochemical behaviors were recorded. The results suggest that, contrary to conventional SOFCs that show sulfur poisoning and CO2 and H2O tolerance, such proton-conducting SOFCs with Ni-BZCYYb cermet anode seem to be poisoned by all three types of "contaminants". Beyond that, the implications of the experimental observations on understanding the fundamental mechanism of anode hydrogen electrochemical oxidation reaction in proton conducting SOFCs are also discussed.

Proton-Induced Conductivity Enhancement in AlGaN/GaN HEMT Devices

NASA Astrophysics Data System (ADS)

Lee, In Hak; Lee, Chul; Choi, Byoung Ki; Yun, Yeseul; Chang, Young Jun; Jang, Seung Yup

2018-04-01

We investigated the influence of proton irradiation on the AlGaN/GaN high-electron-mobility transistor (HEMT) devices. Unlike previous studies on the degradation behavior upon proton irradiation, we observed improvements in their electrical conductivity and carrier concentration of up to 25% for the optimal condition. As we increased the proton dose, the carrier concentration and the mobility showed a gradual increase and decrease, respectively. From the photoluminescence measurements, we observed a reduction in the near-band-edge peak of GaN ( 366 nm), which correlate on the observed electrical properties. However, neither the Raman nor the X-ray diffraction analysis showed any changes, implying a negligible influence of protons on the crystal structures. We demonstrated that high-energy proton irradiation could be utilized to modify the transport properties of HEMT devices without damaging their crystal structures.

Surface Protonics Promotes Catalysis

PubMed Central

Manabe, R.; Okada, S.; Inagaki, R.; Oshima, K.; Ogo, S.; Sekine, Y.

2016-01-01

Catalytic steam reforming of methane for hydrogen production proceeds even at 473 K over 1 wt% Pd/CeO2 catalyst in an electric field, thanks to the surface protonics. Kinetic analyses demonstrated the synergetic effect between catalytic reaction and electric field, revealing strengthened water pressure dependence of the reaction rate when applying an electric field, with one-third the apparent activation energy at the lower reaction temperature range. Operando–IR measurements revealed that proton conduction via adsorbed water on the catalyst surface occurred during electric field application. Methane was activated by proton collision at the Pd–CeO2 interface, based on the inverse kinetic isotope effect. Proton conduction on the catalyst surface plays an important role in methane activation at low temperature. This report is the first describing promotion of the catalytic reaction by surface protonics. PMID:27905505

Two-Step Reactive Aid Sintering of BaZr0.8Y0.2O3- δ Proton-Conducting Ceramics

NASA Astrophysics Data System (ADS)

Wang, Siwei; Chen, Yan; Zhang, Lingling; Ren, Cong; Chen, Fanglin; Brinkman, Kyle S.

2015-12-01

Ceramic-based proton conductors enable high-temperature hydrogen economy applications such as hydrogen separation membranes, fuel cells, and steam electrolyzers. BaZr0.8Y0.2O3- δ (BZY) proton-conducting oxide possesses the highest level of proton conductivity reported to date, but poor sinterability hinders its widespread utilization. In this paper, we report a two-step reactive aid sintering (TRAS) method involving the introduction of BaCO3 and B2O3-Li2O for the preparation of dense BZY ceramics sintered at 1500°C. The resulting BZY samples showed a pure perovskite structure with a dramatic increase in the relative density to 91.5%. In addition, the shrinkage during sintering was improved to 19.3% by a TRAS method as compared to 2.6% by the conventional solid date reaction method. The bulk conductivity was improved due to enhanced densification, while the grain boundary conductivity decreased due to the blocking behavior of the sintering aid resulting in a decrease in the total conductivity of the samples.

Two-Step Reactive Aid Sintering of BaZr 0.8Y 0.2O 3-δ Proton-Conducting Ceramics

DOE PAGES

Wang, Siwei; Chen, Yan; Zhang, Lingling; ...

2015-10-14

Ceramic-based proton conductors enable high-temperature hydrogen economy applications such as hydrogen separation membranes, fuel cells, and steam electrolyzers. BaZr 0.8Y 0.2O 3-δ (BZY) proton-conducting oxide possesses the highest level of proton conductivity reported to date, but poor sinterability hinders its widespread utilization. Here, we report a two-step reactive aid sintering (TRAS) method involving the introduction of BaCO 3 and B 2O 3-Li 2O for the preparation of dense BZY ceramics sintered at 1500°C. The resulting BZY samples showed a pure perovskite structure with a dramatic increase in the relative density to 91.5%. In addition, the shrinkage during sintering was improvedmore » to 19.3% by a TRAS method as compared to 2.6% by the conventional solid date reaction method. Moreover, the bulk conductivity was improved due to enhanced densification, while the grain boundary conductivity decreased due to the blocking behavior of the sintering aid resulting in a decrease in the total conductivity of the samples.« less

Collisionless solar wind protons: A comparison of kinetic and hydrodynamic descriptions

NASA Technical Reports Server (NTRS)

Leer, E.; Holzer, T. E.

1971-01-01

Kinetic and hydrodynamic descriptions of a collisionless solar wind proton gas are compared. Heat conduction and viscosity are neglected in the hydrodynamic formulation but automatically included in the kinetic formulation. The results of the two models are very nearly the same, indicating that heat conduction and viscosity are not important in the solar wind proton gas beyond about 0.1 AU. It is concluded that the hydrodynamic equations provide a valid description of the collisionless solar wind protons, and hence that future models of the quiet solar wind should be based on a hydrodynamic formulation.

Nerve Conduction Through Dendrites via Proton Hopping.

PubMed

Kier, Lemont B

2017-01-01

In our previous studies of nerve conduction conducted by proton hopping, we have considered the axon, soma, synapse and the nodes of Ranvier. The role of proton hopping described the passage of information through each of these units of a typical nerve system. The synapse projects information from the axon to the dendrite and their associated spines. We have invoked the passage of protons via a hopping mechanism to illustrate the continuum of the impulse through the system, via the soma following the dendrites. This is proposed to be a continuum invoked by the proton hopping method. With the proposal of the activity through the dendrites, via proton hopping, a complete model of the nerve function is invoked. At each step to the way, a water pathway is present and is invoked in the proposed model as the carrier of the message via proton hopping. The importance of the dendrites is evident by the presence of a vast number of spines, each possessing the possibility to carry unique messages through the nervous system. With this model of the role of dendrites, functioning with the presence of proton hopping, a complete model of the nerve system is presented. The validity of this model will be available for further studies and models to assess it's validity. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Sulfonated Holey Graphene Oxide (SHGO) Filled Sulfonated Poly(ether ether ketone) Membrane: The Role of Holes in the SHGO in Improving Its Performance as Proton Exchange Membrane for Direct Methanol Fuel Cells.

PubMed

Jiang, Zhong-Jie; Jiang, Zhongqing; Tian, Xiaoning; Luo, Lijuan; Liu, Meilin

2017-06-14

Sulfonated holey graphene oxides (SHGOs) have been synthesized by the etching of sulfonated graphene oxides with concentrated HNO 3 under the assistance of ultrasonication. These SHGOs could be used as fillers for the sulfonated aromatic poly(ether ether ketone) (SPEEK) membrane. The obtained SHGO-incorporated SPEEK membrane has a uniform and dense structure, exhibiting higher performance as proton exchange membranes (PEMs), for instance, higher proton conductivity, lower activation energy for proton conduction, and comparable methanol permeability, as compared to Nafion 112. The sulfonated graphitic structure of the SHGOs is believed to be one of the crucial factors resulting in the higher performance of the SPEEK/SHGO membrane, since it could increase the local density of the -SO 3 H groups in the membrane and induce a strong interfacial interaction between SHGO and the SPEEK matrix, which improve the proton conductivity and lower the swelling ratio of the membrane, respectively. Additionally, the proton conductivity of the membrane could be further enhanced by the presence of the holes in the graphitic planes of the SHGOs, since it provides an additional channel for transport of the protons. When used, direct methanol fuel cell with the SPEEK/SHGO membrane is found to exhibit much higher performance than that with Nafion 112, suggesting potential use of the SPEEK/SHGO membrane as the PEMs.

Enhancement in Proton Conductivity and Thermal Stability in Nafion Membranes Induced by Incorporation of Sulfonated Carbon Nanotubes.

PubMed

Yin, Chongshan; Li, Jingjing; Zhou, Yawei; Zhang, Haining; Fang, Pengfei; He, Chunqing

2018-04-25

Proton exchange membrane fuel cell (PEMFC) is one of the most promising green power sources, in which perfluorinated sulfonic acid ionomer-based membranes (e.g., Nafion) are widely used. However, the widespread application of PEMFCs is greatly limited by the sharp degradation in electrochemical properties of the proton exchange membranes under high temperature and low humidity conditions. In this work, the high-performance sulfonated carbon nanotubes/Nafion composite membranes (Su-CNTs/Nafion) for the PEMFCs were prepared and the mechanism of the microstructures on the macroscopic properties of membranes was intensively studied. Microstructure evolution in Nafion membranes during water uptake was investigated by positron annihilation lifetime spectroscopy, and results strongly showed that the Su-CNTs or CNTs in Nafion composite membranes significantly reinforced Nafion matrices, which influenced the development of ionic-water clusters in them. Proton conductivities in Su-CNTs/Nafion composite membranes were remarkably enhanced due to the mass formation of proton-conducting pathways (water channels) along the Su-CNTs. In particular, these pathways along Su-CNTs in Su-CNTs/Nafion membranes interconnected the isolated ionic-water clusters at low humidity and resulted in less tortuosity of the water channel network for proton transportation at high humidity. At a high temperature of 135 °C, Su-CNTs/Nafion membranes maintained high proton conductivity because the reinforcement of Su-CNTs on Nafion matrices reduced the evaporation of water molecules from membranes as well as the hydrophilic Su-CNTs were helpful for binding water molecules.

Polybenzimidazole block copolymers for fuel cell: synthesis and studies of block length effects on nanophase separation, mechanical properties, and proton conductivity of PEM.

PubMed

Maity, Sudhangshu; Jana, Tushar

2014-05-14

A series of meta-polybenzimidazole-block-para-polybenzimidazole (m-PBI-b-p-PBI), segmented block copolymers of PBI, were synthesized with various structural motifs and block lengths by condensing the diamine terminated meta-PBI (m-PBI-Am) and acid terminated para-PBI (p-PBI-Ac) oligomers. NMR studies and existence of two distinct glass transition temperatures (Tg), obtained from dynamical mechanical analysis (DMA) results, unequivocally confirmed the formation of block copolymer structure through the current polymerization methodology. Appropriate and careful selection of oligomers chain length enabled us to tailor the block length of block copolymers and also to make varieties of structural motifs. Increasingly distinct Tg peaks with higher block length of segmented block structure attributed the decrease in phase mixing between the meta-PBI and para-PBI blocks, which in turn resulted into nanophase segregated domains. The proton conductivities of proton exchange membrane (PEM) developed from phosphoric acid (PA) doped block copolymer membranes were found to be increasing substantially with increasing block length of copolymers even though PA loading of these membranes did not alter appreciably with varying block length. For example when molecular weight (Mn) of blocks were increased from 1000 to 5500 then the proton conductivities at 160 °C of resulting copolymers increased from 0.05 to 0.11 S/cm. Higher block length induced nanophase separation between the blocks by creating less morphological barrier within the block which facilitated the movement of the proton in the block and hence resulting higher proton conductivity of the PEM. The structural varieties also influenced the phase separation and proton conductivity. In comparison to meta-para random copolymers reported earlier, the current meta-para segmented block copolymers were found to be more suitable for PBI-based PEM.

Organic/inorganic hybrid synaptic transistors gated by proton conducting methylcellulose films

NASA Astrophysics Data System (ADS)

Wan, Chang Jin; Zhu, Li Qiang; Wan, Xiang; Shi, Yi; Wan, Qing

2016-01-01

The idea of building a brain-inspired cognitive system has been around for several decades. Recently, electric-double-layer transistors gated by ion conducting electrolytes were reported as the promising candidates for synaptic electronics and neuromorphic system. In this letter, indium-zinc-oxide transistors gated by proton conducting methylcellulose electrolyte films were experimentally demonstrated with synaptic plasticity including paired-pulse facilitation and spatiotemporal-correlated dynamic logic. More importantly, a model based on proton-related electric-double-layer modulation and stretched-exponential decay function was proposed, and the theoretical results are in good agreement with the experimentally measured synaptic behaviors.

Organic/inorganic hybrid synaptic transistors gated by proton conducting methylcellulose films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wan, Chang Jin; Wan, Qing, E-mail: wanqing@nju.edu.cn, E-mail: yshi@nju.edu.cn; Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201

The idea of building a brain-inspired cognitive system has been around for several decades. Recently, electric-double-layer transistors gated by ion conducting electrolytes were reported as the promising candidates for synaptic electronics and neuromorphic system. In this letter, indium-zinc-oxide transistors gated by proton conducting methylcellulose electrolyte films were experimentally demonstrated with synaptic plasticity including paired-pulse facilitation and spatiotemporal-correlated dynamic logic. More importantly, a model based on proton-related electric-double-layer modulation and stretched-exponential decay function was proposed, and the theoretical results are in good agreement with the experimentally measured synaptic behaviors.

Anisotropic Dye Adsorption and Anhydrous Proton Conductivity in Smectic Liquid Crystal Networks: The Role of Cross-Link Density, Order, and Orientation.

PubMed

Liang, Ting; van Kuringen, Huub P C; Mulder, Dirk J; Tan, Shuai; Wu, Yong; Borneman, Zandrie; Nijmeijer, Kitty; Schenning, Albertus P H J

2017-10-11

In this work, the decisive role of rigidity, orientation, and order in the smectic liquid crystalline network on the anisotropic proton and adsorbent properties is reported. The rigidity in the hydrogen-bonded polymer network has been altered by changing the cross-link density, the order by using different mesophases (smectic, nematic, and isotropic phases), whereas the orientation of the mesogens was controlled by alignment layers. Adding more cross-linkers improved the integrity of the polymer films. For the proton conduction, an optimum was found in the amount of cross-linker and the smectic organization results in the highest anhydrous proton conduction. The polymer films show anisotropic proton conductivity with a 54 times higher conductivity in the direction perpendicular to the molecular director. After a base treatment of the smectic liquid crystalline network, a nanoporous polymer film is obtained that also shows anisotropic adsorption of dye molecules and again straight smectic pores are favored over disordered pores in nematic and isotropic networks. The highly cross-linked films show size-selective adsorption of dyes. Low cross-linked materials do not show this difference due to swelling, which decreases the order and creates openings in the two-dimensional polymer layers. The latter is, however, beneficial for fast adsorption kinetics.

Towards the next generation of solid oxide fuel cells operating below 600 °c with chemically stable proton-conducting electrolytes.

PubMed

Fabbri, Emiliana; Bi, Lei; Pergolesi, Daniele; Traversa, Enrico

2012-01-10

The need for reducing the solid oxide fuel cell (SOFC) operating temperature below 600 °C is imposed by cost reduction, which is essential for widespread SOFC use, but might also disclose new applications. To this aim, high-temperature proton-conducting (HTPC) oxides have gained widespread interest as electrolyte materials alternative to oxygen-ion conductors. This Progress Report describes recent developments in electrolyte, anode, and cathode materials for protonic SOFCs, addressing the issue of chemical stability, processability, and good power performance below 600 °C. Different fabrication methods are reported for anode-supported SOFCs, obtained using state-of-the-art, chemically stable proton-conducting electrolyte films. Recent findings show significant improvements in the power density output of cells based on doped barium zirconate electrolytes, pointing out towards the feasibility of the next generation of protonic SOFCs, including a good potential for the development of miniaturized SOFCs as portable power supplies. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cross-linked sulfonated aromatic ionomers via SO2 bridges: Conductivity properties

NASA Astrophysics Data System (ADS)

Di Vona, M. L.; Pasquini, L.; Narducci, R.; Pelzer, K.; Donnadio, A.; Casciola, M.; Knauth, P.

2013-12-01

The proton conductivity of SPEEK membranes in situ cross-linked by thermal treatment at 180 °C for various times was investigated by impedance spectroscopy. The conductivity measurements were made on fully humidified membranes between 25 and 65 °C and on membranes exposed to different relative humidity between 80 and 140 °C. The Ionic Exchange Capacity (IEC) was determined by acid-base titration and the water uptake by gravimetry. The proton conductivity was determined as function of temperature, IEC, degree of cross-linking and hydration number. A curve of proton conductivity vs. hydration number allows predicting that in order to reach a value of 0.1 S/cm at 100 °C a hydration number above 20 is necessary. The measured conductivity at this temperature is 0.16 S/cm for a hydration number of 60.

Alpha-helical hydrophobic polypeptides form proton-selective channels in lipid bilayers

NASA Technical Reports Server (NTRS)

Oliver, A. E.; Deamer, D. W.

1994-01-01

Proton translocation is important in membrane-mediated processes such as ATP-dependent proton pumps, ATP synthesis, bacteriorhodopsin, and cytochrome oxidase function. The fundamental mechanism, however, is poorly understood. To test the theoretical possibility that bundles of hydrophobic alpha-helices could provide a low energy pathway for ion translocation through the lipid bilayer, polyamino acids were incorporated into extruded liposomes and planar lipid membranes, and proton translocation was measured. Liposomes with incorporated long-chain poly-L-alanine or poly-L-leucine were found to have proton permeability coefficients 5 to 7 times greater than control liposomes, whereas short-chain polyamino acids had relatively little effect. Potassium permeability was not increased markedly by any of the polyamino acids tested. Analytical thin layer chromatography measurements of lipid content and a fluorescamine assay for amino acids showed that there were approximately 135 polyleucine or 65 polyalanine molecules associated with each liposome. Fourier transform infrared spectroscopy indicated that a major fraction of the long-chain hydrophobic peptides existed in an alpha-helical conformation. Single-channel recording in both 0.1 N HCl and 0.1 M KCl was also used to determine whether proton-conducting channels formed in planar lipid membranes (phosphatidylcholine/phosphatidylethanolamine, 1:1). Poly-L-leucine and poly-L-alanine in HCl caused a 10- to 30-fold increase in frequency of conductive events compared to that seen in KCl or by the other polyamino acids in either solution. This finding correlates well with the liposome observations in which these two polyamino acids caused the largest increase in membrane proton permeability but had little effect on potassium permeability. Poly-L-leucine was considerably more conductive than poly-L-alanine due primarily to larger event amplitudes and, to a lesser extent, a higher event frequency. Poly-L-leucine caused two populations of conductive events, one in the 0.1-0.5 pA range, and one in the 1.0-5.0 pA range, whereas nearly all events caused by poly-L-alanine were in the 0.1-0.5 pA range at an applied voltage of +60 mV. The channel-like activity appeared to switch between conductive and nonconductive states, with most open-times in the range of 50-200 ms. We conclude that hydrophobic polyamino acids produce proton-conducting defects in lipid bilayers that may be used to model functional proton channels in biological membranes.

Design of flexible polyphenylene proton-conducting membrane for next-generation fuel cells.

PubMed

Miyake, Junpei; Taki, Ryunosuke; Mochizuki, Takashi; Shimizu, Ryo; Akiyama, Ryo; Uchida, Makoto; Miyatake, Kenji

2017-10-01

Proton exchange membrane fuel cells (PEMFCs) are promising devices for clean power generation in automotive, stationary, and portable applications. Perfluorosulfonic acid (PFSA) ionomers (for example, Nafion) have been the benchmark PEMs; however, several problems, including high gas permeability, low thermal stability, high production cost, and environmental incompatibility, limit the widespread dissemination of PEMFCs. It is believed that fluorine-free PEMs can potentially address all of these issues; however, none of these membranes have simultaneously met the criteria for both high performance (for example, proton conductivity) and durability (for example, mechanical and chemical stability). We present a polyphenylene-based PEM (SPP-QP) that fulfills the required properties for fuel cell applications. The newly designed PEM exhibits very high proton conductivity, excellent membrane flexibility, low gas permeability, and extremely high stability, with negligible degradation even under accelerated degradation conditions, which has never been achieved with existing fluorine-free PEMs. The polyphenylene PEM also exhibits reasonably high fuel cell performance, with excellent durability under practical conditions. This new PEM extends the limits of existing fluorine-free proton-conductive materials and will help to realize the next generation of PEMFCs via cost reduction as well as the performance improvement compared to the present PFSA-based PEMFC systems.

A Methodological Approach for Conducting a Business Case Analysis (BCA) of the Global Observer Joint Capability Technology Demonstration (JCTD)

DTIC Science & Technology

2007-12-01

Justthebasics.html [Accessed September 29, 2007]. [8] Smithsonian National Museum of American History . “ Proton Exchange Membrame (PEM) Fuel Cell...hydrogen-rich fuel, is fed to the anode where a catalyst separates hydrogen’s negatively charged electrons from the positively charged protons ...The protons are conducted through the electrolyte to the cathode, whereas the electrons are forced to travel in an external circuit, due to the

Uncoupling protein and ATP/ADP carrier increase mitochondrial proton conductance after cold adaptation of king penguins.

PubMed

Talbot, Darren A; Duchamp, Claude; Rey, Benjamin; Hanuise, Nicolas; Rouanet, Jean Louis; Sibille, Brigitte; Brand, Martin D

2004-07-01

Juvenile king penguins develop adaptive thermogenesis after repeated immersion in cold water. However, the mechanisms of such metabolic adaptation in birds are unknown, as they lack brown adipose tissue and uncoupling protein-1 (UCP1), which mediate adaptive non-shivering thermogenesis in mammals. We used three different groups of juvenile king penguins to investigate the mitochondrial basis of avian adaptive thermogenesis in vitro. Skeletal muscle mitochondria isolated from penguins that had never been immersed in cold water showed no superoxide-stimulated proton conductance, indicating no functional avian UCP. Skeletal muscle mitochondria from penguins that had been either experimentally immersed or naturally adapted to cold water did possess functional avian UCP, demonstrated by a superoxide-stimulated, GDP-inhibitable proton conductance across their inner membrane. This was associated with a markedly greater abundance of avian UCP mRNA. In the presence (but not the absence) of fatty acids, these mitochondria also showed a greater adenine nucleotide translocase-catalysed proton conductance than those from never-immersed penguins. This was due to an increase in the amount of adenine nucleotide translocase. Therefore, adaptive thermogenesis in juvenile king penguins is linked to two separate mechanisms of uncoupling of oxidative phosphorylation in skeletal muscle mitochondria: increased proton transport activity of avian UCP (dependent on superoxide and inhibited by GDP) and increased proton transport activity of the adenine nucleotide translocase (dependent on fatty acids and inhibited by carboxyatractylate).

Mixed anion materials and compounds for novel proton conducting membranes

DOEpatents

Poling, Steven Andrew; Nelson, Carly R.; Martin, Steve W.

2006-09-05

The present invention provides new amorphous or partially crystalline mixed anion chalcogenide compounds for use in proton exchange membranes which are able to operate over a wide variety of temperature ranges, including in the intermediate temperature range of about 100 .degree. C. to 300.degree. C., and new uses for crystalline mixed anion chalcogenide compounds in such proton exchange membranes. In one embodiment, the proton conductivity of the compounds is between about 10.sup.-8 S/cm and 10.sup.-1 S/cm within a temperature range of between about -60 and 300.degree. C. and a relative humidity of less than about 12%..

Compounds for novel proton conducting membranes and methods of making same

DOEpatents

Poling, Steven A.; Martin, Steve W.; Sutherland, Jacob T.

2006-03-28

The present invention provides new compounds for use in proton exchange membranes which are able to operate in a wide variety of temperature ranges, including in the intermediate temperature range of about 100.degree. C. to 700.degree. C., and new and improved methods of making these compounds. The present invention also provides new and improved methods for making chalcogenide compounds, including, but not limited to, non-protonated sulfide, selenide and telluride compounds. In one embodiment, the proton conductivity of the compounds is between about 10.sup.-8 S/cm and 10.sup.-1 S/cm within a temperature range of between about -50 and 500.degree. C.

High throughput study of fuel cell proton exchange membranes: Poly(vinylidene fluoride)/acrylic polyelectrolyte blends and nanocomposites with zirconium

NASA Astrophysics Data System (ADS)

Zapata B., Pedro Jose

Sustainability is perhaps one of the most heard buzzwords in the post-20 th century society; nevertheless, it is not without a reason. Our present practices for energy supply are largely unsustainable if we consider their environmental and social impact. In view of this unfavorable panorama, alternative sustainable energy sources and conversion approaches have acquired noteworthy significance in recent years. Among these, proton exchange membrane fuel cells (PEMFCs) are being considered as a pivotal building block in the transition towards a sustainable energy economy in the 21st century. The polyelectrolyte membrane or proton exchange membrane (PEM) is a vital component, as well as a performance-limiting factor, of the PEMFC. Consequently, the development of high-performance PEM materials is of utmost importance for the advance of the PEMFC field. In this work, alternative PEM materials based on semi-interpenetrated networks from blends of poly(vinyledene fluoride) (PVDF) (inert phase) and sulfonated crosslinked acrylic polyelectrolytes (PE) (proton-conducting phase), as well as tri-phase PVDF/PE/zirconium-based composites, are studied. To alleviate the burden resulting from the vast number of possible combinations of the different precursors utilized in the preparation of the membranes (PVDF: 5x, PE: 2x, Nanoparticle: 3x), custom high-throughput (HT) screening systems have been developed for their characterization. By coupling the data spaces obtained via these systems with the appropriate statistical and data analysis tools it was found that, despite not being directly involved in the proton transport process, the inert PVDF phase plays a major role on proton conductivity. Particularly, a univocal inverse correlation between the PVDF crystalline characteristics (i.e., crystallinity and crystallite size) and melt viscosity, and membrane proton conductivity was discovered. Membranes based on highly crystalline and viscous PVDF homopolymers exhibited reduced proton conductivity due to precluded segmental motion and physical blockage of the PE chains during crosslinking. In addition, a maximum effective amount of PE (55-60wt%, neutralized form) beneficial for proton conductivity was revealed. Some of the aforementioned effects may possibly have been overlooked if a high-throughput study including plentiful combinations of multiple precursors hadn't been performed. In the case of composite membranes, despite the fact that nanoparticle dispersion was thermodynamically limited, a general improvement in proton conductivity was evidenced at low to medium nanoparticle loadings (0.5 to 1wt%) in comparison to non-hybrid PVDF/PE references. This beneficial effect was particularly noticeable in membranes based on PVDF homopolymers (7% to 14.3% increment), where the nanoparticles induced a "healing" effect by providing proton-conducting paths between non-crosslinked PE channels separated by dense PVDF areas resulting from large PVDF crystallites. In general, the results presented herein are promising for the development of new cost-effective alternative PEMs.

Cross-linked polyelectrolyte for direct methanol fuel cells applications based on a novel sulfonated cross-linker

NASA Astrophysics Data System (ADS)

Li, Mingyu; Zhang, Gang; Xu, Shuai; Zhao, Chengji; Han, Miaomiao; Zhang, Liyuan; Jiang, Hao; Liu, Zhongguo; Na, Hui

2014-06-01

A novel type of cross-linked proton exchange membrane of lower methanol permeation and high proton conductivity is prepared, based on a newly synthesized sulfonated cross-linker: carboxyl terminated benzimidazole trimer bearing sulfonic acid groups (s-BI). Compared to membranes cross-linked with non-sulfonated cross-linker (BI), SPEEK/s-BI-n membranes show higher IEC values and proton conductivities. Meanwhile, oxidative stability and mechanical property of SPEEK/s-BI-n membranes are obviously improved. Among SPEEK/s-BI-n membranes, SPEEK/s-BI-2 exhibits high proton conductivity, low swelling ratio (0.122 S cm-1 and 15.2% at 60 °C, respectively) and low methanol permeability coefficient. These results imply that the cross-linked membranes prepared with the newly sulfonated cross-linker are promising for the direct methanol fuel cells (DMFCs) application.

Proton conducting sol-gel sulfonated membranes produced from 2-allylphenol, 3-glycidoxypropyl trimethoxysilane and tetraethyl orthosilicate

NASA Astrophysics Data System (ADS)

Mosa, J.; Durán, A.; Aparicio, M.

An important research area in proton exchange membrane fuel cells (PEMFC) is devoted to the development of low cost membranes able to work at temperatures higher than 100 °C. In this work, homogeneous, transparent and crack-free hybrid membranes have been synthesized using tetraethyl orthosilicate (TEOS), 3-glycidoxipropyl trimethoxysilane (GPTMS) and 2-allylphenol (AP) as precursors. The synthesis of proton conducting membranes was performed by a post-sulfonation method using trimethylsilyl chlorosulfonate as a mild sulfonating agent. The water retention properties provided by sulfonate and hydroxyl groups and the high porosity leads to relatively high proton conductivity (maximum values around 1.3 × 10 -3 S cm -1 at 140 °C and 100% RH) for membranes treated at 180 °C and sulfonated for 2 h.

Density Functional Theory Investigation of Proton Diffusion in Tungsten Oxide And Its Hydrates

NASA Astrophysics Data System (ADS)

Lin, Hao

Fast proton conduction mechanism is of key importance for achieving high performance in fuel cell membranes, batteries, supercapacitors, and electrochromic materials. Enhanced proton diffusion is often observed in hydrated materials where it is thought to occur via the famous Grotthuss mechanism through pathways formed by structural water. Using first-principles calculations, we demonstrate that proton diffusion in tungsten oxide dihydrate (WO3·2H 2O), a known good proton conductor, takes place within the layers of corner-sharing WO6 octahedra without direct involvement of structural water. The calculated proton migration barrier in WO3·2H 2O is in good agreement with the experimental value inferred from the temperature dependence of conductivity. The preferred proton diffusion path in WO3·2H2O is essentially the same as in gamma-WO 3. In contrast to the small intercalation voltages calculated for WO 3 and WO3·2H2O, we find that proton absorption in the monohydrate WO3·H2O is energetically highly favorable. However, strong proton-proton repulsion limits the equilibrium H content at zero voltage. We find a fast one-dimensional diffusion channel in WO3·H2O at dilute proton concentrations, but much higher barriers are expected at near-equilibrium concentrations due to strong repulsive interactions with other protons. Our results illustrate that low proton diffusion barriers and low insertion voltages both contribute to fast proton transport in bulk WO3·2H2O and gamma-WO 3.

Solid-state proton conductors

NASA Astrophysics Data System (ADS)

Jewulski, J. R.; Osif, T. L.; Remick, R. J.

1990-12-01

The purpose of this program was to survey the field of solid-state proton conductors (SSPC), identify conductors that could be used to develop solid-state fuel cells suitable for use with coal derived fuel gases, and begin the experimental research required for the development of these fuel cells. This document covers the following topics: the history of developments and current status of the SSPC, including a review of proton conducting electrolyte structures, the current status of the medium temperature SSPC development, electrodes for moderate temperature (SSPC) fuel cell, basic material and measurement techniques applicable for SSPC development, modeling, and optimization studies. Correlation and optimization studies are described which include correlation studies on proton conduction and oxide cathode optimization for the SSPC fuel cell. Experiments with the SSPC fuel cells are presented which include the fabrication of the electrolyte disks, apparatus for conducting measurements, the strontium-cerium based electrolyte, the barium-cerium based electrolyte with solid foil electrodes, the barium-cerium based electrolyte with porous electrodes, and conduction mechanisms.

3-dimensional free standing micro-structures by proton beam writing of Su 8-silver nanoParticle polymeric composite

NASA Astrophysics Data System (ADS)

Igbenehi, H.; Jiguet, S.

2012-09-01

Proton beam lithography a maskless direct-write lithographic technique (well suited for producing 3-Dimensional microstructures in a range of resist and semiconductor materials) is demonstrated as an effective tool in the creation of electrically conductive freestanding micro-structures in an Su 8 + Nano Silver polymer composite. The structures produced show non-ohmic conductivity and fit the percolation theory conduction model of tunneling of separated nanoparticles. Measurements show threshold switching and a change in conductivity of at least 4 orders of magnitude. The predictable range of protons in materials at a given energy is exploited in the creation of high aspect ratio, free standing micro-structures, made from a commercially available SU8 Silver nano-composite (GMC3060 form Gersteltec Inc. a negative tone photo-epoxy with added metallic nano-particles(Silver)) to create films with enhanced electrical properties when exposed and cured. Nano-composite films are directly written on with a finely focused MeV accelerated Proton particle beam. The energy loss of the incident proton beams in the target polymer nano- composite film is concentrated at the end of its range, where damage occurs; changing the chemistry of the nano-composite film via an acid initiated polymerization - creating conduction paths. Changing the energy of the incident beams provide exposed regions with different penetration and damage depth - exploited in the demonstrated cantilever microstructure.

Proton-conducting membrane based on epoxy resin-poly(vinyl alcohol)-sulfosuccinic acid blend and its nanocomposite with sulfonated multiwall carbon nanotubes for fuel-cell application

NASA Astrophysics Data System (ADS)

Kakati, Nitul; Das, Gautam; Yoon, Young Soo

2016-01-01

A blend of poly(vinyl alcohol) (PVA) with diglycidyl ether of bisphenol-A (DGB) in the presence of sulfosuccinic acid (SSA) was investigated as hydrolytically-stable proton-conducting membrane. The PVA modification was carried out by varying the DGB:SSA ratio (20:20, 10:20, and 5:20). A nanocomposite of the blend (20:20) was prepared with sulfonated multiwall carbon nanotubes (viz., 1, 3 and 5 wt%). The water uptake behavior and the proton conductivity of the prepared membranes were evaluated. The ionic conductivity of the membranes and the water uptake behavior depended on the s-MWCNT and the DGB contents. The ionic conductivity showed an enhancement for the blend and for the nanocomposite membrane as compared to the pristine polymer.

Acid-Group-Content-Dependent Proton Conductivity Mechanisms at the Interlayer of Poly(N-dodecylacrylamide-co-acrylic acid) Copolymer Multilayer Nanosheet Films.

PubMed

Sato, Takuma; Tsukamoto, Mayu; Yamamoto, Shunsuke; Mitsuishi, Masaya; Miyashita, Tokuji; Nagano, Shusaku; Matsui, Jun

2017-11-14

The effect of the content of acid groups on the proton conductivity at the interlayer of polymer-nanosheet assemblies was investigated. For that purpose, amphiphilic poly(N-dodecylacrylamide-co-acrylic acid) copolymers [p(DDA/AA)] with varying contents of AA were synthesized by free radical polymerization. Surface pressure (π)-area (A) isotherms of these copolymers indicated that stable polymer monolayers are formed at the air/water interface for AA mole fraction (n) ≤ 0.49. In all cases, a uniform dispersion of the AA groups in the polymer monolayer was observed. Subsequently, polymer monolayers were transferred onto solid substrates using the Langmuir-Blodgett (LB) technique. X-ray diffraction (XRD) analyses of the multilayer films showed strong Bragg diffraction peaks, suggesting a highly uniform lamellar structure for the multilayer films. The proton conductivity of the multilayer films parallel to the direction of the layer planes were measured by impedance spectroscopy, which revealed that the conductivity increased with increasing values of n. Activation energies for proton conduction of ∼0.3 and 0.42 eV were observed for n ≥ 0.32 and n = 0.07, respectively. Interestingly, the proton conductivity of a multilayer film with n = 0.19 did not follow the Arrhenius equation. These results were interpreted in terms of the average distance between the AA groups (l AA ), and it was concluded that, for n ≥ 0.32, an advanced 2D hydrogen bonding network was formed, while for n = 0.07, l AA is too long to form such hydrogen bonding networks. The l AA for n = 0.19 is intermediate to these extremes, resulting in the formation of hydrogen bonding networks at low temperatures, and disruption of these networks at high temperatures due to thermally induced motion. These results indicate that a high proton conductivity with low activation energy can be achieved, even under weakly acidic conditions, by arranging the acid groups at an optimal distance.

Atomic Scale Picture of the Ion Conduction Mechanism in Tetrahedral Network of Lanthanum Barium Gallate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jalarvo, Niina H; Gourdon, Olivier; Bi, Zhonghe

2013-01-01

Combined experimental study of impedance spectroscopy, neutron powder diffraction and quasielastic neutron scattering was performed to shed light into the atomic scale ion migration processes in proton and oxide ion conductor; La0.8Ba1.2GaO3.9 . This material consist of tetrahedral GaO4 units, which are rather flexible and rocking motion of these units promotes the ionic migration process. The oxide ion (vacancy) conduction takes place on channels along c axis, involving a single elementary step, which occurs between adjacent tetrahedron (inter-tetrahedron jump). The proton conduction mechanism consists of intra-tetrahedron and inter-tetrahedron elementary processes. The intra-tetrahedron proton transport is the rate-limiting process, with activationmore » energy of 0.44 eV. The rocking motion of the GaO4 tetrahedron aids the inter-tetrahedral proton transport, which has the activation energy of 0.068 eV.« less

Oriented MOF-polymer Composite Nanofiber Membranes for High Proton Conductivity at High Temperature and Anhydrous Condition

PubMed Central

Wu, Bin; Pan, Jiefeng; Ge, Liang; Wu, Liang; Wang, Huanting; Xu, Tongwen

2014-01-01

The novel oriented electrospun nanofiber membrane composed of MOFs and SPPESK has been synthesized for proton exchange membrane fuel cell operating at high temperature and anhydrous conditions. It is clear that the oriented nanofiber membrane displays the higher proton conductivity than that of the disordered nanofiber membrane or the membrane prepared by conventional solvent-casting method (without nanofibers). Nanofibers within the membranes are significantly oriented. The proton conductivity of the oriented nanofiber membrane can reach up to (8.2 ± 0.16) × 10−2 S cm−1 at 160°C under anhydrous condition for the highly orientation of nanofibers. Moreover, the oxidative stability and resistance of methanol permeability of the nanofibers membrane are obviously improved with an increase in orientation of nanofibers. The observed methanol permeability of 0.707 × 10−7 cm2 s−1 is about 6% of Nafion-115. Consequently, orientated nanofibers membrane is proved to be a promising material as the proton exchange membrane for potential application in direct methanol fuel cells. PMID:25082522

Uncoupling protein and ATP/ADP carrier increase mitochondrial proton conductance after cold adaptation of king penguins

PubMed Central

Talbot, Darren A; Duchamp, Claude; Rey, Benjamin; Hanuise, Nicolas; Rouanet, Jean Louis; Sibille, Brigitte; Brand, Martin D

2004-01-01

Juvenile king penguins develop adaptive thermogenesis after repeated immersion in cold water. However, the mechanisms of such metabolic adaptation in birds are unknown, as they lack brown adipose tissue and uncoupling protein-1 (UCP1), which mediate adaptive non-shivering thermogenesis in mammals. We used three different groups of juvenile king penguins to investigate the mitochondrial basis of avian adaptive thermogenesis in vitro. Skeletal muscle mitochondria isolated from penguins that had never been immersed in cold water showed no superoxide-stimulated proton conductance, indicating no functional avian UCP. Skeletal muscle mitochondria from penguins that had been either experimentally immersed or naturally adapted to cold water did possess functional avian UCP, demonstrated by a superoxide-stimulated, GDP-inhibitable proton conductance across their inner membrane. This was associated with a markedly greater abundance of avian UCP mRNA. In the presence (but not the absence) of fatty acids, these mitochondria also showed a greater adenine nucleotide translocase-catalysed proton conductance than those from never-immersed penguins. This was due to an increase in the amount of adenine nucleotide translocase. Therefore, adaptive thermogenesis in juvenile king penguins is linked to two separate mechanisms of uncoupling of oxidative phosphorylation in skeletal muscle mitochondria: increased proton transport activity of avian UCP (dependent on superoxide and inhibited by GDP) and increased proton transport activity of the adenine nucleotide translocase (dependent on fatty acids and inhibited by carboxyatractylate). PMID:15146050

Advances in proton-exchange membranes for fuel cells: an overview on proton conductive channels (PCCs).

PubMed

Wu, Liang; Zhang, Zhenghui; Ran, Jin; Zhou, Dan; Li, Chuanrun; Xu, Tongwen

2013-04-14

Proton-exchange membranes (PEM) display unique ion-selective transport that has enabled a breakthrough in high-performance proton-exchange membrane fuel cells (PEMFCs). Elemental understanding of the morphology and proton transport mechanisms of the commercially available Nafion® has promoted a majority of researchers to tune proton conductive channels (PCCs). Specifically, knowledge of the morphology-property relationship gained from statistical and segmented copolymer PEMs has highlighted the importance of the alignment of PCCs. Furthermore, increasing efforts in fabricating and aligning artificial PCCs in field-aligned copolymer PEMs, nanofiber composite PEMs and mesoporous PEMs have set new paradigms for improvement of membrane performances. This perspective profiles the recent development of the channels, from the self-assembled to the artificial, with a particular emphasis on their formation and alignment. It concludes with an outlook on benefits of highly aligned PCCs for fuel cell operation, and gives further direction to develop new PEMs from a practical point of view.

Morphology and Proton Transport in Humidified Phosphonated Peptoid Block Copolymers

DOE PAGES

Sun, Jing; Jiang, Xi; Siegmund, Aaron; ...

2016-04-04

Polymers that conduct protons in the hydrated state are of crucial importance in a wide variety of clean energy applications such as hydrogen fuel cells and artificial photosynthesis. Phosphonated and sulfonated polymers are known to conduct protons at low water content. In this study, we report on the synthesis phosphonated peptoid diblock copolymers, poly-N-(2-ethyl)hexylglycine-block-poly-N-phosphonomethylglycine (pNeh-b-pNpm), with volume fractions of pNpm (Φ Npm) values ranging from 0.13 to 0.44 and dispersity (¯D) ≤ 1.0003. The morphologies of the dry block copolypeptoids were determined by transmission electron microscopy and in both the dry and hydrated states by synchrotron small-angle X-ray scattering. Drymore » samples with Φ Npm > 0.13 exhibited a lamellar morphology. Upon hydration, the lowest molecular weight sample transitioned to a hexagonally packed cylinder morphology, while the others maintained their dry morphologies. Water uptake of all of the ordered samples was 8.1 ± 1.1 water molecules per phosphonate group. In spite of this, the proton conductivity of the ordered pNeh-b-pNpm copolymers ranged from 0.002 to 0.008 S/cm. Finally, we demonstrate that proton conductivity is maximized in high molecular weight, symmetric pNeh-b-pNpm copolymers.« less

Design of flexible polyphenylene proton-conducting membrane for next-generation fuel cells

PubMed Central

Miyake, Junpei; Taki, Ryunosuke; Mochizuki, Takashi; Shimizu, Ryo; Akiyama, Ryo; Uchida, Makoto; Miyatake, Kenji

2017-01-01

Proton exchange membrane fuel cells (PEMFCs) are promising devices for clean power generation in automotive, stationary, and portable applications. Perfluorosulfonic acid (PFSA) ionomers (for example, Nafion) have been the benchmark PEMs; however, several problems, including high gas permeability, low thermal stability, high production cost, and environmental incompatibility, limit the widespread dissemination of PEMFCs. It is believed that fluorine-free PEMs can potentially address all of these issues; however, none of these membranes have simultaneously met the criteria for both high performance (for example, proton conductivity) and durability (for example, mechanical and chemical stability). We present a polyphenylene-based PEM (SPP-QP) that fulfills the required properties for fuel cell applications. The newly designed PEM exhibits very high proton conductivity, excellent membrane flexibility, low gas permeability, and extremely high stability, with negligible degradation even under accelerated degradation conditions, which has never been achieved with existing fluorine-free PEMs. The polyphenylene PEM also exhibits reasonably high fuel cell performance, with excellent durability under practical conditions. This new PEM extends the limits of existing fluorine-free proton-conductive materials and will help to realize the next generation of PEMFCs via cost reduction as well as the performance improvement compared to the present PFSA-based PEMFC systems. PMID:29075671

Morphology and Proton Transport in Humidified Phosphonated Peptoid Block Copolymers

PubMed Central

2016-01-01

Polymers that conduct protons in the hydrated state are of crucial importance in a wide variety of clean energy applications such as hydrogen fuel cells and artificial photosynthesis. Phosphonated and sulfonated polymers are known to conduct protons at low water content. In this paper, we report on the synthesis phosphonated peptoid diblock copolymers, poly-N-(2-ethyl)hexylglycine-block-poly-N-phosphonomethylglycine (pNeh-b-pNpm), with volume fractions of pNpm (ϕNpm) values ranging from 0.13 to 0.44 and dispersity (Đ) ≤ 1.0003. The morphologies of the dry block copolypeptoids were determined by transmission electron microscopy and in both the dry and hydrated states by synchrotron small-angle X-ray scattering. Dry samples with ϕNpm > 0.13 exhibited a lamellar morphology. Upon hydration, the lowest molecular weight sample transitioned to a hexagonally packed cylinder morphology, while the others maintained their dry morphologies. Water uptake of all of the ordered samples was 8.1 ± 1.1 water molecules per phosphonate group. In spite of this, the proton conductivity of the ordered pNeh-b-pNpm copolymers ranged from 0.002 to 0.008 S/cm. We demonstrate that proton conductivity is maximized in high molecular weight, symmetric pNeh-b-pNpm copolymers. PMID:27134312

Random and Block Sulfonated Polyaramides as Advanced Proton Exchange Membranes

DOE PAGES

Kinsinger, Corey L.; Liu, Yuan; Liu, Feilong; ...

2015-10-09

We present here the experimental and computational characterization of two novel copolyaramide proton exchange membranes (PEMs) with higher conductivity than Nafion at relatively high temperatures, good mechanical properties, high thermal stability, and the capability to operate in low humidity conditions. The random and block copolyaramide PEMs are found to possess different ion exchange capacities (IEC) in addition to subtle structural and morphological differences, which impact the stability and conductivity of the membranes. SAXS patterns indicate the ionomer peak for the dry block copolymer resides at q = 0.1 Å –1, which increases in amplitude when initially hydrated to 25% relativemore » humidity, but then decrease in amplitude with additional hydration. This pattern is hypothesized to signal the transport of water into the polymer matrix resulting in a reduced degree of phase separation. Coupled to these morphological changes, the enhanced proton transport characteristics and structural/mechanical stability for the block copolymer are hypothesized to be primarily due to the ordered structure of ionic clusters that create connected proton transport pathways while reducing swelling upon hydration. Interestingly, the random copolymer did not possess an ionomer peak at any of the hydration levels investigated, indicating a lack of any significant ionomer structure. The random copolymer also demonstrated higher proton conductivity than the block copolymer, which is opposite to the trend normally seen in polymer membranes. However, it has reduced structural/mechanical stability as compared to the block copolymer. In conclusion, this reduction in stability is due to the random morphology formed by entanglements of polymer chains and the adverse swelling characteristics upon hydration. Therefore, the block copolymer with its enhanced proton conductivity characteristics, as compared to Nafion, and favorable structural/mechanical stability, as compared to the random copolymer, represents a viable alternative to current proton exchange membranes.« less

Voltage and pH sensing by the voltage-gated proton channel, HV1.

PubMed

DeCoursey, Thomas E

2018-04-01

Voltage-gated proton channels are unique ion channels, membrane proteins that allow protons but no other ions to cross cell membranes. They are found in diverse species, from unicellular marine life to humans. In all cells, their function requires that they open and conduct current only under certain conditions, typically when the electrochemical gradient for protons is outwards. Consequently, these proteins behave like rectifiers, conducting protons out of cells. Their activity has electrical consequences and also changes the pH on both sides of the membrane. Here we summarize what is known about the way these proteins sense the membrane potential and the pH inside and outside the cell. Currently, it is hypothesized that membrane potential is sensed by permanently charged arginines (with very high p K a ) within the protein, which results in parts of the protein moving to produce a conduction pathway. The mechanism of pH sensing appears to involve titratable side chains of particular amino acids. For this purpose their p K a needs to be within the operational pH range. We propose a 'counter-charge' model for pH sensing in which electrostatic interactions within the protein are selectively disrupted by protonation of internally or externally accessible groups. © 2018 The Author.

Voltage and pH sensing by the voltage-gated proton channel, HV1

PubMed Central

2018-01-01

Voltage-gated proton channels are unique ion channels, membrane proteins that allow protons but no other ions to cross cell membranes. They are found in diverse species, from unicellular marine life to humans. In all cells, their function requires that they open and conduct current only under certain conditions, typically when the electrochemical gradient for protons is outwards. Consequently, these proteins behave like rectifiers, conducting protons out of cells. Their activity has electrical consequences and also changes the pH on both sides of the membrane. Here we summarize what is known about the way these proteins sense the membrane potential and the pH inside and outside the cell. Currently, it is hypothesized that membrane potential is sensed by permanently charged arginines (with very high pKa) within the protein, which results in parts of the protein moving to produce a conduction pathway. The mechanism of pH sensing appears to involve titratable side chains of particular amino acids. For this purpose their pKa needs to be within the operational pH range. We propose a ‘counter-charge’ model for pH sensing in which electrostatic interactions within the protein are selectively disrupted by protonation of internally or externally accessible groups. PMID:29643227

Theoretical Investigation of oxides for batteries and fuel cell applications

NASA Astrophysics Data System (ADS)

Ganesh, Panchapakesan; Lubimtsev, Andrew A.; Balachandran, Janakiraman

I will present theoretical studies of Li-ion and proton-conducting oxides using a combination of theory and computations that involve Density Functional Theory based atomistic modeling, cluster-expansion based studies, global optimization, high-throughput computations and machine learning based investigation of ionic transport in oxide materials. In Li-ion intercalated oxides, we explain the experimentally observed (Nature Materials 12, 518-522 (2013)) 'intercalation pseudocapacitance' phenomenon, and explain why Nb2O5 is special to show this behavior when Li-ions are intercalated (J. Mater. Chem. A, 2013,1, 14951-14956), but not when Na-ions are used. In addition, we explore Li-ion intercalation theoretically in VO2 (B) phase, which is somewhat structurally similar to Nb2O5 and predict an interesting role of site-trapping on the voltage and capacity of the material, validated by ongoing experiments. Computations of proton conducting oxides explain why Y-doped BaZrO3 , one of the fastest proton conducting oxide, shows a decrease in conductivity above 20% Y-doping. Further, using high throughput computations and machine learning tools we discover general principles to improve proton conductivity. Acknowledgements: LDRD at ORNL and CNMS at ORNL

Composite electrolyte with proton conductivity for low-temperature solid oxide fuel cell

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raza, Rizwan, E-mail: razahussaini786@gmail.com; Department of Energy Technology, Royal Institute of Technology, KTH, Stockholm 10044; Ahmed, Akhlaq

In the present work, cost-effective nanocomposite electrolyte (Ba-SDC) oxide is developed for efficient low-temperature solid oxide fuel cells (LTSOFCs). Analysis has shown that dual phase conduction of O{sup −2} (oxygen ions) and H{sup +} (protons) plays a significant role in the development of advanced LTSOFCs. Comparatively high proton ion conductivity (0.19 s/cm) for LTSOFCs was achieved at low temperature (460 °C). In this article, the ionic conduction behaviour of LTSOFCs is explained by carrying out electrochemical impedance spectroscopy measurements. Further, the phase and structure analysis are investigated by X-ray diffraction and scanning electron microscopy techniques. Finally, we achieved an ionic transport numbermore » of the composite electrolyte for LTSOFCs as high as 0.95 and energy and power density of 90% and 550 mW/cm{sup 2}, respectively, after sintering the composite electrolyte at 800 °C for 4 h, which is promising. Our current effort toward the development of an efficient, green, low-temperature solid oxide fuel cell with the incorporation of high proton conductivity composite electrolyte may open frontiers in the fields of energy and fuel cell technology.« less

Protonic Conduction of BaCe0.85YO. 1503 Doped with SrTiO3

NASA Technical Reports Server (NTRS)

Dynys, Frederick W.; Sayir, Ali

2005-01-01

Reformers based on ceramic membrane technology potentially offer hydrogen production that is comparable to the cost of fossil fuels. Protonic conducting ceramic with the chemical formula AB03 offers the promise of highly selective hydrogen separation at intermediate temperature (400-800 C). Among different perovskite-type oxides, BaCe03 and SrCe03 based compositions show high protonic conductivities but strong resistance to densification. X-ray diffraction studies on sintered specimens of BaCe0.85Y0.1503-6 show multi-phase formation which was found to show dependence upon powder synthesis method. Doping with SrTiO3 suppresses multi-phase formation and enhances grain growth. Conductivity measurements in temperature range of 200 to 1000 C were performed by ac impedance spectroscopy under dry and wet conditions. Sintering behavior, phase formation and conductivity results will be reported.

A highly stable two-dimensional copper(II)-organic framework for proton conduction and ammonia impedance sensing.

PubMed

Sun, Zhibing; Yu, Shihang; Zhao, Lili; Wang, Jifeng; Li, Zifeng; Li, Gang

2018-05-22

This work reports on the design and fabrication of a proton conductive 2D MOF, [Cu(p-IPhHIDC)]n (1) (p-IPhH3IDC = 2-(p-N-imidazol-1-yl)-phenyl-1H-imidazole-4,5dicarboxylic acid) as an advanced ammonia impedance sensor at room temperature and 68-98% RHs. MOF 1 shows the optimized proton conductivity value of 1.51 × 10-3 S·cm-1 at 100 C and 98% RH. Its temperature-dependent and humidity-dependent proton conduction properties have been explored. The large amount of uncoordinated carboxylate groups between the layers play a vital role in the resultant conductivity. Distinctly, the fabricated MOF-based sensor displays the required stability to NH3, enhanced sensitivity and notable selectivity to NH3 gas. At room temperature and 68% RH, it indicates a remarkable gas response of 8620% to 130 ppm of NH3 gas and lower detection limit (2 ppm) towards NH3 gas. It is also found that the gas response of the ammonia sensor increases linearly with the increase of NH3 gas concentration under 68-98% RHs and room temperature. Moreover, the sensor indicates excellent reversibility and selectivity toward NH3 vs N2, H2, O2, CO, CO2, benzene and MeOH. Based on structural analyses, activation energy calculations, water and NH3 vapor absorptions, and PXRD determinations, the proton conduction and NH3 sensing mechanisms are suggested. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Some notes on hydrogen-related point defects and their role in the isotope exchange and electrical conductivity in olivine

NASA Astrophysics Data System (ADS)

Karato, Shun-ichiro

2015-11-01

Nominally anhydrous minerals such as olivine dissolve hydrogen in a variety of forms including free (or interstitial) proton (Hrad) and two protons trapped at the M-site ((2 H)M×). The strength of chemical bonding between protons and the surrounding atoms are different among different species, and consequently protons belonging to different species likely have different mobility (diffusion coefficients). I discuss the role of diffusion of protons in different species in the isotope exchange and hydrogen-assisted electrical conductivity adding a few notes to the previous work by Karato (2013) including a new way to test the model. I conclude that in the case of isotope exchange, the interaction among these species is strong because diffusion is heterogeneous, whereas there is no strong interaction among different species in electrical conduction where diffusion is homogeneous (in an infinite crystal). Consequently, the slowest diffusing species controls the rate of isotope exchange, whereas the fastest diffusing species controls electrical conductivity leading to a different temperature dependence of activation energy and anisotropy. This model explains the differences in the activation energy and anisotropy between isotope diffusion and electrical conductivity, and predicts that the mechanism of electrical conductivity changes with temperature providing an explanation for most of the discrepancies among different experimental observations at different temperatures except for those by Poe et al. (2010) who reported anomalously high water content dependence and highly anisotropic activation energy. When the results obtained at high temperatures are used, most of the geophysically observed high and highly anisotropic electrical conductivity in the asthenosphere can be explained without invoking partial melting.

Steam electrolysis by solid oxide electrolysis cells (SOECs) with proton-conducting oxides.

PubMed

Bi, Lei; Boulfrad, Samir; Traversa, Enrico

2014-12-21

Energy crisis and environmental problems caused by the conventional combustion of fossil fuels boost the development of renewable and sustainable energies. H2 is regarded as a clean fuel for many applications and it also serves as an energy carrier for many renewable energy sources, such as solar and wind power. Among all the technologies for H2 production, steam electrolysis by solid oxide electrolysis cells (SOECs) has attracted much attention due to its high efficiency and low environmental impact, provided that the needed electrical power is generated from renewable sources. However, the deployment of SOECs based on conventional oxygen-ion conductors is limited by several issues, such as high operating temperature, hydrogen purification from water, and electrode stability. To avoid these problems, proton-conducting oxides are proposed as electrolyte materials for SOECs. This review paper provides a broad overview of the research progresses made for proton-conducting SOECs, summarizing the past work and finding the problems for the development of proton-conducting SOECs, as well as pointing out potential development directions.

Proton-conducting Micro-solid Oxide Fuel Cells with Improved Cathode Reactions by a Nanoscale Thin Film Gadolinium-doped Ceria Interlayer

PubMed Central

Li, Yong; Wang, Shijie; Su, Pei-Chen

2016-01-01

An 8 nm-thick gadolinium-doped ceria (GDC) layer was inserted as a cathodic interlayer between the nanoscale proton-conducting yttrium-doped barium zirconate (BZY) electrolyte and the porous platinum cathode of a micro-solid oxide fuel cell (μ-SOFC), which has effectively improved the cathode reaction kinetics and rendered high cell power density. The addition of the GDC interlayer significantly reduced the cathodic activation loss and increased the peak power density of the μ-SOFC by 33% at 400 °C. The peak power density reached 445 mW/cm2 at 425 °C, which is the highest among the reported μ-SOFCs using proton-conducting electrolytes. The impressive performance was attributed to the mixed protonic and oxygen ionic conducting properties of the nano-granular GDC, and also to the high densities of grain boundaries and lattice defects in GDC interlayer that favored the oxygen incorporation and transportation during the oxygen reduction reaction (ORR) and the water evolution reaction at cathode. PMID:26928192

Dramatic improvement in water retention and proton conductivity in electrically aligned functionalized CNT/SPEEK nanohybrid PEM.

PubMed

Gahlot, Swati; Kulshrestha, Vaibhav

2015-01-14

Nanohybrid membranes of electrically aligned functionalized carbon nanotube f CNT with sulfonated poly ether ether ketone (SPEEK) have been successfully prepared by solution casting. Functionalization of CNTs was done through a carboxylation and sulfonation route. Further, a constant electric field (500 V·cm(-2)) has been applied to align CNTs in the same direction during the membrane drying process. All the membranes are characterized chemically, thermally, and mechanically by the means of FTIR, DSC, DMA, UTM, SEM, TEM, and AFM techniques. Intermolecular interactions between the components in hybrid membranes are established by FTIR. Physicochemical measurements were done to analyze membrane stability. Membranes are evaluated for proton conductivity (30-90 °C) and methanol crossover resistance to reveal their potential for direct methanol fuel cell application. Incorporation of f CNT reasonably increases the ion-exchange capacity, water retention, and proton conductivity while it reduces the methanol permeability. The maximum proton conductivity has been found in the S-sCNT-5 nanohybrid PEM with higher methanol crossover resistance. The prepared membranes can be also used for electrode material for fuel cells and batteries.

Acid-doped polymer nanofiber framework: Three-dimensional proton conductive network for high-performance fuel cells

NASA Astrophysics Data System (ADS)

Tanaka, Manabu; Takeda, Yasushi; Wakiya, Takeru; Wakamoto, Yuta; Harigaya, Kaori; Ito, Tatsunori; Tarao, Takashi; Kawakami, Hiroyoshi

2017-02-01

High-performance polymer electrolyte membranes (PEMs) with excellent proton conductivity, gas barrier property, and membrane stability are desired for future fuel cells. Here we report the development of PEMs based on our proposed new concept "Nanofiber Framework (NfF)." The NfF composite membranes composed of phytic acid-doped polybenzimidazole nanofibers (PBINf) and Nafion matrix show higher proton conductivity than the recast-Nafion membrane without nanofibers. A series of analyses reveal the formation of three-dimensional network nanostructures to conduct protons and water effectively through acid-condensed layers at the interface of PBINf and Nafion matrix. In addition, the NfF composite membrane achieves high gas barrier property and distinguished membrane stability. The fuel cell performance by the NfF composite membrane, which enables ultra-thin membranes with their thickness less than 5 μm, is superior to that by the recast-Nafion membrane, especially at low relative humidity. Such NfF-based high-performance PEM will be accomplished not only by the Nafion matrix used in this study but also by other polymer electrolyte matrices for future PEFCs.

An interacting spin-flip model for one-dimensional proton conduction

NASA Astrophysics Data System (ADS)

Chou, Tom

2002-05-01

A discrete asymmetric exclusion process (ASEP) is developed to model proton conduction along one-dimensional water wires. Each lattice site represents a water molecule that can be in only one of three states; protonated, left-pointing and right-pointing. Only a right- (left-) pointing water can accept a proton from its left (). Results of asymptotic mean field analysis and Monte Carlo simulations for the three-species, open boundary exclusion model are presented and compared. The mean field results for the steady-state proton current suggest a number of regimes analogous to the low and maximal current phases found in the single-species ASEP (Derrida B 1998 Phys. Rep. 301 65-83). We find that the mean field results are accurate (compared with lattice Monte Carlo simulations) only in certain regimes. Refinements and extensions including more elaborate forces and pore defects are also discussed.

Radiation-grafted proton exchange membranes based on co-grafting from binary monomer mixtures into poly(ethylene-co-tetrafluoroethylene) (ETFE) film

NASA Astrophysics Data System (ADS)

Sohn, Joon-Yong; Sung, Hae-Jun; Song, Joo-Myung; Shin, Junhwa; Nho, Young-Chang

2012-08-01

In this study, proton exchange membranes (PEMs) based on a poly(ethylene-co-tetrafluoroethylene) (ETFE) film were synthesized through the graft copolymerization of styrene and VTMS (vinyltrimethoxysilane), or styrene and TMSPM (3-(trimethoxysilyl) propyl methacrylate) binary monomer systems using a simultaneous irradiation method. The prepared membranes with the similar degrees of grafting were investigated by measuring ion exchange capacity, proton conductivity, water uptake, chemical stability, and dimensional stability. The results indicate that the silane-crosslinked proton exchange membrane (PEM) has not only lower water uptake and dimensional change but also high proton conductivity at low humidity condition compared to non-crosslinked poly(ethylene-co-tetrafluoroethylene)-g-poly(styrene sulfonic acid) (ETFE-g-PSSA). Also, the chemical stability of silane-crosslinked fuel cell membranes was more improved than that of non-crosslinked fuel cell membrane.

Inhibitors of Proton Pumping

PubMed Central

Bisson, Mary A.

1986-01-01

Reported inhibitors of the Characean plasmalemma proton pump were tested for their ability to inhibit the passive H+ conductance which develops in Chara corallina Klein ex Willd. at high pH. Diethylstilbestrol inhibits the proton pump and the passive H+ conductance with about the same time course, at concentrations that have no effect on cytoplasmic streaming. N-Ethylmaleimide, a sulfhydryl reagent which is small and relatively nonpolar, also inhibits both pumping and passive conductance of H+. However, it also inhibits cytoplasmic streaming with about the same time course, and therefore could not be considered a specific ATPase inhibitor. p-Chloromercuribenzene sulfonate (PCMBS), a sulfhydryl reagent which is large and charged and hence less able to penetrate the membrane, does not inhibit pumping or conductance at low concentration. At high concentration, PCMBS sometimes inhibits pumping without affecting H+ conductance, but since streaming is also inhibited, the effect on the pump cannot be said to be specific. 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide, a water soluble carbodiimide, weakly inhibits both pump and conductance, apparently specifically. PMID:16664807

Magnetically aligned nanodomains: application in high-performance ion conductive membranes.

PubMed

Hasani-Sadrabadi, Mohammad Mahdi; Majedi, Fatemeh Sadat; Coullerez, Géraldine; Dashtimoghadam, Erfan; VanDersarl, Jules John; Bertsch, Arnaud; Moaddel, Homayoun; Jacob, Karl I; Renaud, Philippe

2014-05-28

Polyelectrolyte-coated magnetic nanoparticles were prepared by decorating the surface of superparamagnetic iron oxide nanoparticles (SPIONs) with crosslinked chitosan oligopolysaccharide (CS). These positively charged particles (CS-SPIONs) were then added to a negatively charged polymer (Nafion), and cast into membranes under an applied magnetic field. TEM and SAXS measurements confirmed this process created aligned, cylindrical nanodomains in the membranes. This was also indirectly confirmed by proton conductivity values. The strong electrostatic interaction between chitosan and Nafion prevented oxygen permeability and water evaporation at elevated temperatures through the proton conductive channels. The resultant proton exchange membranes showed lower conduction dependency to relative humidity, which is highly desirable for hydrogen fuel cells. The fuel cell performance tests were performed on the designed polyelectrolyte membrane by hydrogen-oxygen single cells at elevated temperature (120 °C) and low relative humidity.

XFEL structures of the influenza M2 proton channel: Room temperature water networks and insights into proton conduction

DOE PAGES

Thomaston, Jessica L.; Woldeyes, Rahel A.; Nakane, Takanori; ...

2017-08-23

The M2 proton channel of influenza A is a drug target that is essential for the reproduction of the flu virus. It is also a model system for the study of selective, unidirectional proton transport across a membrane. Ordered water molecules arranged in “wires” inside the channel pore have been proposed to play a role in both the conduction of protons to the four gating His37 residues and the stabilization of multiple positive charges within the channel. To visualize the solvent in the pore of the channel at room temperature while minimizing the effects of radiation damage, data were collectedmore » to a resolution of 1.4 Å using an X-ray free-electron laser (XFEL) at three different pH conditions: pH 5.5, pH 6.5, and pH 8.0. Data were collected on the Inward open state, which is an intermediate that accumulates at high protonation of the His37 tetrad. At pH 5.5, a continuous hydrogen-bonded network of water molecules spans the vertical length of the channel, consistent with a Grotthuss mechanism model for proton transport to the His37 tetrad. This ordered solvent at pH 5.5 could act to stabilize the positive charges that build up on the gating His37 tetrad during the proton conduction cycle. The number of ordered pore waters decreases at pH 6.5 and 8.0, where the Inward open state is less stable. Furthermore, these studies provide a graphical view of the response of water to a change in charge within a restricted channel environment.« less

Excess protons in water-acetone mixtures. II. A conductivity study.

PubMed

Semino, Rocío; Longinotti, M Paula

2013-10-28

In the present work we complement a previous simulation study [R. Semino and D. Laria, J. Chem. Phys. 136, 194503 (2012)] on the disruption of the proton transfer mechanism in water by the addition of an aprotic solvent, such as acetone. We provide experimental measurements of the mobility of protons in aqueous-acetone mixtures in a wide composition range, for water molar fractions, xw, between 0.05 and 1.00. Furthermore, new molecular dynamics simulation results are presented for rich acetone mixtures, which provide further insight into the proton transport mechanism in water-non-protic solvent mixtures. The proton mobility was analyzed between xw 0.05 and 1.00 and compared to molecular dynamics simulation data. Results show two qualitative changes in the proton transport composition dependence at xw ∼ 0.25 and 0.8. At xw < 0.25 the ratio of the infinite dilution molar conductivities of HCl and LiCl, Λ(0)(HCl).Λ(0)(LiCl)(-1), is approximately constant and equal to one, since the proton diffusion is vehicular and equal to that of Li(+). At xw ∼ 0.25, proton mobility starts to differ from that of Li(+) indicating that above this concentration the Grotthuss transport mechanism starts to be possible. Molecular dynamics simulation results showed that at this threshold concentration the probability of interconversion between two Eigen structures starts to be non-negligible. At xw ∼ 0.8, the infinite molar conductivity of HCl concentration dependence qualitatively changes. This result is in excellent agreement with the analysis presented in the previous simulation work and it has been ascribed to the interchange of water and acetone molecules in the second solvation shell of the hydronium ion.

XFEL structures of the influenza M2 proton channel: Room temperature water networks and insights into proton conduction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomaston, Jessica L.; Woldeyes, Rahel A.; Nakane, Takanori

The M2 proton channel of influenza A is a drug target that is essential for the reproduction of the flu virus. It is also a model system for the study of selective, unidirectional proton transport across a membrane. Ordered water molecules arranged in “wires” inside the channel pore have been proposed to play a role in both the conduction of protons to the four gating His37 residues and the stabilization of multiple positive charges within the channel. To visualize the solvent in the pore of the channel at room temperature while minimizing the effects of radiation damage, data were collectedmore » to a resolution of 1.4 Å using an X-ray free-electron laser (XFEL) at three different pH conditions: pH 5.5, pH 6.5, and pH 8.0. Data were collected on the Inward open state, which is an intermediate that accumulates at high protonation of the His37 tetrad. At pH 5.5, a continuous hydrogen-bonded network of water molecules spans the vertical length of the channel, consistent with a Grotthuss mechanism model for proton transport to the His37 tetrad. This ordered solvent at pH 5.5 could act to stabilize the positive charges that build up on the gating His37 tetrad during the proton conduction cycle. The number of ordered pore waters decreases at pH 6.5 and 8.0, where the Inward open state is less stable. Furthermore, these studies provide a graphical view of the response of water to a change in charge within a restricted channel environment.« less

Improvement in the mechanical properties, proton conductivity, and methanol resistance of highly branched sulfonated poly(arylene ether)/graphene oxide grafted with flexible alkylsulfonated side chains nanocomposite membranes

NASA Astrophysics Data System (ADS)

Liu, Dong; Peng, Jinhua; Li, Zhuoyao; Liu, Bin; Wang, Lei

2018-02-01

Sulfonated polymer/graphene oxide (GO) nanocomposites exhibit excellent properties as proton exchange membranes. However, few investigations on highly branched sulfonated poly(arylene ether)s (HBSPE)/GO nanocomposites as proton exchange membranes are reported. In order to obtain HBSPE-based nanocomposite membranes with better dispersibility and properties, a novel GO containing flexible alkylsulfonated side chains (SGO) is designed and prepared for the first time in this work. The HBSPE/SGO nanocomposite membranes with excellent dispersibility are successfully prepared. The properties of these membranes, including the mechanical properties, ion-exchange capacity, water uptake, proton conductivity, and methanol resistance, are characterized. The nanocomposite membranes exhibit higher tensile strength (32.67 MPa), higher proton conductivity (0.39 S cm-1 at 80 °C) and lower methanol permeability (4.89 × 10-7 cm2 s-1) than the pristine membrane. The nanocomposite membranes also achieve a higher maximum power density (82.36 mW cm-2) than the pristine membrane (67.85 mW cm-2) in single-cell direct methanol fuel cell (DMFC) tests, demonstrating their considerable potential for applications in DMFCs.

Novel structure design of composite proton exchange membranes with continuous and through-membrane proton-conducting channels

NASA Astrophysics Data System (ADS)

Wang, Hang; Tang, Chenxiao; Zhuang, Xupin; Cheng, Bowen; Wang, Wei; Kang, Weimin; Li, Hongjun

2017-10-01

The primary goal of this study is to develop a high-performanced proton exchange membrane with the characteristics of through-membrane and continuous solution blown nanofibers as proton-conducting channels. The curled sulfonated phenolphthalein poly (ether sulfone) and poly (vinylidene fluoride) nanofibers were separately fabricated through the solution blowing process which is a new nanofiber fabricating method with high productivity, then they were fabricated into a sandwich-structured mat. Then this sandwich-structured mat was hot-pressed to form the designed structure using different melting temperatures of the two polymers by melting and making poly (vinylidene fluoride) flow into the phenolphthalein poly (ether sulfone) nanofiber mat. The characteristics of the composite membrane, such as morphology and performance of the membrane, were investigated. The characterization results proved the successful preparation of the membrane structure. Performance results showed that the novel structured membrane with through-membrane nanofibers significantly improved water swelling and methanol permeability, though its conductivity is lower than that of Nafion, the cell performance showed comparable results. Therefore, the novel structure design can be considered as a promising method for preparing of proton exchange membranes.

Structure and Dynamics Investigations of Sr/Ca-Doped LaPO 4 Proton Conductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

al-Wahish, Amal; al-Binni, U.; Tetard, L.

Proton conductors loom out of the pool of candidate materials with great potential to boost hydrogen alternatives to fossil-based resources for energy. Acceptor doped lanthanum orthophosphates are considered for solid oxide fuel cells (SOFCs) for their potential stability and conductivity at high temperature. By exploring the crystal and defect structure of x% Sr/Ca-doped LaPO 4 with different nominal Sr/Ca concentrations (x = 0 – 10) with Neutron powder diffraction (NPD) and X-ray powder diffraction (XRD), we confirm that Sr/Ca-doped LaPO 4 can exist as self-supported structures at high temperatures during solid oxide fuel cell operation. Thermal stability, surface topography, sizemore » distribution are also studied to better understand the proton conductivity for dry and wet compounds obtained at sintering temperatures ranging from 1200 to 1400 °C using a combination of scanning electron microscopy (SEM), Atomic Force Microscopy (AFM), Fourier transform infrared spectroscopy (FTIR) and electrochemical impedance spectroscopy (EIS). In conclusion, the results suggest that Sr doped samples exhibit the highest proton conductivity of our samples and illustrate the impact of material design and versatile characterization schemes on the development of proton conductors with superior functionality.« less

An ingenious one-dimensional zirconium phosphonate with efficient strontium exchange capability and moderate proton conductivity.

PubMed

Zhang, Jiarong; Chen, Lanhua; Gui, Daxiang; Zhang, Haowen; Zhang, Duo; Liu, Wei; Huang, Guolin; Diwu, Juan; Chai, Zhifang; Wang, Shuao

2018-04-17

A new 1-D zirconium phosphonate [(CH3)2NH2]2[Zr(CH2(HPO3)(PO3))2] (SZ-5) was synthesized via a solvothermal reaction and its single crystal structure was elucidated. SZ-5 exhibits efficient strontium exchange capability with high uptake capacity and selectivity, as further demonstrated by the radioactive Sr-90 removal from a real contaminated seawater sample with an extremely high ionic strength. In addition, the measured proton conductivity at 90 °C and 90% relative humidity (RH) is 5.65 × 10-4 S cm-1. The efficient ion-exchange ability and the moderate proton conductivity suggest the potential applications of SZ-5 in fuel cells or in the remediation of contaminated water.

Surface proton transport of fully protonated poly(aspartic acid) thin films on quartz substrates

NASA Astrophysics Data System (ADS)

Nagao, Yuki; Kubo, Takahiro

2014-12-01

Thin film structure and the proton transport property of fully protonated poly(aspartic acid) (P-Asp100) have been investigated. An earlier study assessed partially protonated poly(aspartic acid), highly oriented thin film structure and enhancement of the internal proton transport. In this study of P-Asp100, IR p-polarized multiple-angle incidence resolution (P-MAIR) spectra were measured to investigate the thin film structure. The obtained thin films, with thicknesses of 120-670 nm, had no oriented structure. Relative humidity dependence of the resistance, proton conductivity, and normalized resistance were examined to ascertain the proton transport property of P-Asp100 thin films. The obtained data showed that the proton transport of P-Asp100 thin films might occur on the surface, not inside of the thin film. This phenomenon might be related with the proton transport of the biological system.

Proton dynamics of phosphoric acid in HT-PEFCs: Towards "operando" experiments

NASA Astrophysics Data System (ADS)

Khaneft, Marina; Shuai, Liu; Lin, Yu; Janßen, Holger; Lüke, Wiebke; Zorn, Reiner; Ivanova, Oxana; Radulescu, Aurel; Holderer, Olaf; Lehnert, Werner

2018-05-01

High Temperature Polymer Electrolyte Fuel Cells (HT-PEFCs) have been studied with quasielastic neutron scattering, which gives access to the proton diffusion in the fuel cell on local length- and timescales. So far, the different components such as the proton conducting membrane and the electrode layers have been studied separately. Here we show that also operating fuel cells can be investigated and the proton diffusion can be measured under real working conditions. The proton diffusion during power production is compared to that "at rest" but at elevated temperatures.

Role of Water in Proton-Hydroxide Conductance Across Model and Biological Membranes

DTIC Science & Technology

1990-09-01

esearch - CONTRACT TITLE: Role of water in proton-hydroxide conductan, e across model Maim and biological membranes. RESEARCH OBJECTIVES: Our goals over...establish a model system for measuring proton flux along hydrogen bonded chains of water in hydrophobic phases. TRAINING ACTIVITIES: Three doctoral and two...to general anesthetics. Biochim. Biophys. Acta 944:40- 48. 6. Deamer, D.W. and Nichols, J.W. (1989) Proton flux in model and biological membranes. J

Sensor Properties of Field-Effect Transistors Based on Graphene Oxide and Nafion Films with Proton Conductivity

NASA Astrophysics Data System (ADS)

Smirnov, V. A.; Mokrushin, A. D.; Denisov, N. N.; Dobrovolsky, Yu. A.

2018-07-01

The proton conductivity of graphene oxide (GO) and Nafion films was studied depending on the humidity and voltage on electrodes. The electric properties of the films were similar, but the mobility of positive charges in Nafion was approximately two orders of magnitude higher than in GO. In GO films, the negative ion current with a positive voltage bias was up to 10% of the proton current, while in Nafion films it was almost absent (<1%). The sensors based on GO and Nafion films were most effective at humidity (RH) in the range 20-80%.

Anisotropic amplification of proton transport in proton exchange membrane fuel cells

NASA Astrophysics Data System (ADS)

Thimmappa, Ravikumar; Fawaz, Mohammed; Devendrachari, Mruthyunjayachari Chattanahalli; Gautam, Manu; Kottaichamy, Alagar Raja; Shafi, Shahid Pottachola; Thotiyl, Musthafa Ottakam

2017-07-01

Though graphene oxide (GO) membrane shuttles protons under humid conditions, it suffer severe disintegration and anhydrous conditions lead to abysmal ionic conductivity. The trade-off between mechanical integrity and ionic conductivity challenge the amplification of GO's ionic transport under anhydrous conditions. We show anisotropic amplification of GO's ionic transport with a selective amplification of in plane contribution under anhydrous conditions by doping it with a plant extract, phytic acid (PA). The hygroscopic nature of PA stabilized interlayer water molecules and peculiar geometry of sbnd OH functionalities around saturated hydrocarbon ring anisotropically enhanced ionic transport amplifying the fuel cell performance metrics.

Theory of passive proton conductance in lipid bilayers.

PubMed

Nagle, J F

1987-10-01

The large permeability of lipid bilayers to protons compared to other small ions calls for a special proton transport mechanism. At the present time, only mechanisms involving transient hydrogen-bonded chains of water can account for the experimental result that the conductance is nearly independent of pH. Three models involving transient hydrogen-bonded chains are discussed, including an outline of the kinetic calculations that lead to predictions of current versus voltage drop and current versus pH differences. These calculations can be compared to experiment to determine which, if any, of these models pertains to lipid bilayers.

Advanced Materials for PEM-Based Fuel Cell Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

James E. McGrath; Donald G. Baird; Michael von Spakovsky

2005-10-26

Proton exchange membrane fuel cells (PEMFCs) are quickly becoming attractive alternative energy sources for transportation, stationary power, and small electronics due to the increasing cost and environmental hazards of traditional fossil fuels. Two main classes of PEMFCs include hydrogen/air or hydrogen/oxygen fuel cells and direct methanol fuel cells (DMFCs). The current benchmark membrane for both types of PEMFCs is Nafion, a perfluorinated sulfonated copolymer made by DuPont. Nafion copolymers exhibit good thermal and chemical stability, as well as very high proton conductivity under hydrated conditions at temperatures below 80 degrees C. However, application of these membranes is limited due tomore » their high methanol permeability and loss of conductivity at high temperatures and low relative humidities. These deficiencies have led to the search for improved materials for proton exchange membranes. Potential PEMs should have good thermal, hydrolytic, and oxidative stability, high proton conductivity, selective permeability, and mechanical durability over long periods of time. Poly(arylene ether)s, polyimides, polybenzimidazoles, and polyphenylenes are among the most widely investigated candidates for PEMs. Poly(arylene ether)s are a promising class of proton exchange membranes due to their excellent thermal and chemical stability and high glass transition temperatures. High proton conductivity can be achieved through post-sulfonation of poly(arylene ether) materials, but this most often results in very high water sorption or even water solubility. Our research has shown that directly polymerized poly(arylene ether) copolymers show important advantages over traditional post-sulfonated systems and also address the concerns with Nafion membranes. These properties were evaluated and correlated with morphology, structure-property relationships, and states of water in the membranes. Further improvements in properties were achieved through incorporation of inorganic fillers, such as phosphotungstic acid and zirconium hydrogen phosphate. Block copolymers were also studied due to the possibility to achieve a desired combination of homopolymer properties as well as the unique morphologies that are possible with block copolymers. Bezoyl substituted poly(p-phenylene) blocks were combined with poly(arylene ether) blocks to merge the structural rigidity of the poly(p-phenylene) with the ductility and high protonic conductivity of the poly(arylene ether)s. As evidenced by our many refereed publications and preprints, the research that we have conducted over the past several years has made a valuable and significant contribution to the literature and to the state of understanding of proton exchange membranes. Our early efforts at scale-up have suggested that the directly polymerized disulfonated poly(arylene ether sulfone) copolymers are commercially viable alternatives for proton exchange membranes. A new process for bipolar plates was developed and is described. An important single domain PEMFC model was developed and is documented in herein.« less

Acceleration and heating of two-fluid solar wind by Alfven waves

NASA Technical Reports Server (NTRS)

Sandbaek, Ornulf; Leer, Egil

1994-01-01

Earlier model studies of solar wind driven by thermal pressure and Alfven waves have shown that wave amplitudes of 20-30 km/s at the coronal base are sufficient to accelerate the flow to the high speeds observed in quasi-steady streams emanating from large coronal holes. We focus on the energy balance in the proton gas and show that heat conduction from the region where the waves are dissipated may play an important role in determining the proton temperature at the orbit of Earth. In models with 'classical' heat conduction we find a correlation between high flow speed, high proton temperature, and low electron temperature at 1 AU. The effect of wave heating on the development of anisotropies in the solar wind proton gas pressure is also investigated in this study.

Composite polymer electrolyte containing ionic liquid and functionalized polyhedral oligomeric silsesquioxanes for anhydrous PEM applications.

PubMed

Subianto, Surya; Mistry, Mayur K; Choudhury, Namita Roy; Dutta, Naba K; Knott, Robert

2009-06-01

A new type of supported liquid membrane was made by combining an ionic liquid (IL) with a Nafion membrane reinforced with multifunctional polyhedral oligomeric silsesquioxanes (POSSs) using a layer-by-layer strategy for anhydrous proton-exchange membrane (PEM) application. The POSS was functionalized by direct sulfonation, and the sulfonated POSS (S-POSS) was incorporated into Nafion 117 membranes by the infiltration method. The resultant hybrid membrane shows strong ionic interaction between the Nafion matrix and the multifunctional POSS, resulting in increased glass transition temperature and thermal stability at very low loadings of S-POSS (1%). The presence of S-POSS has also improved the proton conductivity especially at low humidities, where it shows a marked increase due to its confinement in the ionic domains and promotes water uptake by capillary condensation. In order to achieve anhydrous conductivity, the IL 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMI-BTSI) was incorporated into these membranes to provide proton conduction in the absence of water. Although the incorporation of an IL shows a plasticizing effect on the Nafion membrane, the S-POSS composite membrane with an IL shows a higher modulus at high temperatures compared to Nafion 117 and a Nafion-IL membrane, with significantly higher proton conductivity (5 mS/cm at 150 degrees C with 20% IL). This shows the ability of the multifunctional POSS and IL to work symbiotically to achieve the desirable proton conductivity and mechanical properties of such membranes by enhancing the ionic interaction within the material.

Multiscale simulation reveals a multifaceted mechanism of proton permeation through the influenza A M2 proton channel

PubMed Central

Liang, Ruibin; Li, Hui; Swanson, Jessica M. J.; Voth, Gregory A.

2014-01-01

The influenza A virus M2 channel (AM2) is crucial in the viral life cycle. Despite many previous experimental and computational studies, the mechanism of the activating process in which proton permeation acidifies the virion to release the viral RNA and core proteins is not well understood. Herein the AM2 proton permeation process has been systematically characterized using multiscale computer simulations, including quantum, classical, and reactive molecular dynamics methods. We report, to our knowledge, the first complete free-energy profiles for proton transport through the entire AM2 transmembrane domain at various pH values, including explicit treatment of excess proton charge delocalization and shuttling through the His37 tetrad. The free-energy profiles reveal that the excess proton must overcome a large free-energy barrier to diffuse to the His37 tetrad, where it is stabilized in a deep minimum reflecting the delocalization of the excess charge among the histidines and the cost of shuttling the proton past them. At lower pH values the His37 tetrad has a larger total charge that increases the channel width, hydration, and solvent dynamics, in agreement with recent 2D-IR spectroscopic studies. The proton transport barrier becomes smaller, despite the increased charge repulsion, due to backbone expansion and the more dynamic pore water molecules. The calculated conductances are in quantitative agreement with recent experimental measurements. In addition, the free-energy profiles and conductances for proton transport in several mutants provide insights for explaining our findings and those of previous experimental mutagenesis studies. PMID:24979779

Multiscale simulation reveals a multifaceted mechanism of proton permeation through the influenza A M2 proton channel.

PubMed

Liang, Ruibin; Li, Hui; Swanson, Jessica M J; Voth, Gregory A

2014-07-01

The influenza A virus M2 channel (AM2) is crucial in the viral life cycle. Despite many previous experimental and computational studies, the mechanism of the activating process in which proton permeation acidifies the virion to release the viral RNA and core proteins is not well understood. Herein the AM2 proton permeation process has been systematically characterized using multiscale computer simulations, including quantum, classical, and reactive molecular dynamics methods. We report, to our knowledge, the first complete free-energy profiles for proton transport through the entire AM2 transmembrane domain at various pH values, including explicit treatment of excess proton charge delocalization and shuttling through the His37 tetrad. The free-energy profiles reveal that the excess proton must overcome a large free-energy barrier to diffuse to the His37 tetrad, where it is stabilized in a deep minimum reflecting the delocalization of the excess charge among the histidines and the cost of shuttling the proton past them. At lower pH values the His37 tetrad has a larger total charge that increases the channel width, hydration, and solvent dynamics, in agreement with recent 2D-IR spectroscopic studies. The proton transport barrier becomes smaller, despite the increased charge repulsion, due to backbone expansion and the more dynamic pore water molecules. The calculated conductances are in quantitative agreement with recent experimental measurements. In addition, the free-energy profiles and conductances for proton transport in several mutants provide insights for explaining our findings and those of previous experimental mutagenesis studies.

Life Cycle Assessment for Proton Conducting Ceramics Synthesized by the Sol-Gel Process.

PubMed

Lee, Soo-Sun; Hong, Tae-Whan

2014-09-16

In this report, the environmental aspects of producing proton conducting ceramics are investigated by means of the environmental Life Cycle Assessment (LCA) method. The proton conducting ceramics BaZr 0.8 Y 0.2 O 3-δ (BZY), BaCe 0.9 Y 0.1 O 2.95 (BCY10), and Sr(Ce 0.9 Zr 0.1 ) 0.95 Yb 0.05 O 3-δ (SCZY) were prepared by the sol-gel process. Their material requirements and environmental emissions were inventoried, and their energy requirements were determined, based on actual production data. This latter point makes the present LCA especially worthy of attention as a preliminary indication of future environmental impact. The analysis was performed according to the recommendations of ISO norms 14040 and obtained using the Gabi 6 software. The performance of the analyzed samples was also compared with each other. The LCA results for these proton conducting ceramics production processes indicated that the marine aquatic ecotoxicity potential (MAETP) made up the largest part, followed by fresh-water aquatic ecotoxicity potential (FAETP) and Human Toxicity Potential (HTP). The largest contribution was from energy consumption during annealing and calcinations steps.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Siwei; Chen, Yan; Zhang, Lingling

Ceramic-based proton conductors enable high-temperature hydrogen economy applications such as hydrogen separation membranes, fuel cells, and steam electrolyzers. BaZr 0.8Y 0.2O 3-δ(BZY) proton-conducting oxide possesses the highest level of proton conductivity reported to date, but poor sinterability hinders its widespread utilization. In this paper, we report a two-step reactive aid sintering (TRAS) method involving the introduction of BaCO 3 and B 2O 3-Li 2O for the preparation of dense BZY ceramics sintered at 1500°C. The resulting BZY samples showed a pure perovskite structure with a dramatic increase in the relative density to 91.5%. In addition, the shrinkage during sintering wasmore » improved to 19.3% by a TRAS method as compared to 2.6% by the conventional solid date reaction method. In conclusion, the bulk conductivity was improved due to enhanced densification, while the grain boundary conductivity decreased due to the blocking behavior of the sintering aid resulting in a decrease in the total conductivity of the samples.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Siwei; Chen, Yan; Zhang, Lingling

Ceramic-based proton conductors enable high-temperature hydrogen economy applications such as hydrogen separation membranes, fuel cells, and steam electrolyzers. BaZr 0.8Y 0.2O 3-δ (BZY) proton-conducting oxide possesses the highest level of proton conductivity reported to date, but poor sinterability hinders its widespread utilization. Here, we report a two-step reactive aid sintering (TRAS) method involving the introduction of BaCO 3 and B 2O 3-Li 2O for the preparation of dense BZY ceramics sintered at 1500°C. The resulting BZY samples showed a pure perovskite structure with a dramatic increase in the relative density to 91.5%. In addition, the shrinkage during sintering was improvedmore » to 19.3% by a TRAS method as compared to 2.6% by the conventional solid date reaction method. Moreover, the bulk conductivity was improved due to enhanced densification, while the grain boundary conductivity decreased due to the blocking behavior of the sintering aid resulting in a decrease in the total conductivity of the samples.« less

New High-Temperature Membranes Developed for Proton Exchange Membrane Fuel Cells

NASA Technical Reports Server (NTRS)

Kinder, James D.

2004-01-01

Fuel cells are receiving a considerable amount of attention for potential use in a variety of areas, including the automotive industry, commercial power generation, and personal electronics. Research at the NASA Glenn Research Center has focused on the development of fuel cells for use in aerospace power systems for aircraft, unmanned air vehicles, and space transportation systems. These applications require fuel cells with higher power densities and better durability than what is required for nonaerospace uses. In addition, membrane cost is a concern for any fuel cell application. The most widely used membrane materials for proton exchange membrane (PEM) fuel cells are based on sulfonated perfluorinated polyethers, typically Nafion 117, Flemion, or Aciplex. However, these polymers are costly and do not function well at temperatures above 80 C. At higher temperatures, conventional membrane materials dry out and lose their ability to conduct protons, essential for the operation of the fuel cell. Increasing the operating temperature of PEM fuel cells from 80 to 120 C would significantly increase their power densities and enhance their durability by reducing the susceptibility of the electrode catalysts to carbon monoxide poisoning. Glenn's Polymers Branch has focused on developing new, low-cost membranes that can operate at these higher temperatures. A new series of organically modified siloxane (ORMOSIL) polymers were synthesized for use as membrane materials in a high-temperature PEM fuel cell. These polymers have an organic portion that can allow protons to transport through the polymer film and a cross-linked silica network that gives the polymers dimensional stability. These flexible xerogel polymer films are thermally stable, with decomposition onset as high as 380 C. Two types of proton-conducting ORMOSIL films have been produced: (1) NASA-A, which can coordinate many highly acid inorganic salts that facilitate proton conduction and (2) NASA-B, which has been produced and which incorporates strongly acidic (proton donating) functional groups into the polymer backbone. Both of these polymer films have demonstrated significantly higher proton conductivity than Nafion at elevated temperatures and low relative humidities. An added advantage is that these polymers are very inexpensive to produce because their starting materials are commodity chemicals that are commercially available in large volumes.

Self assembled 12-tungstophosphoric acid-silica mesoporous nanocomposites as proton exchange membranes for direct alcohol fuel cells.

PubMed

Tang, Haolin; Pan, Mu; Jiang, San Ping

2011-05-21

A highly ordered inorganic electrolyte based on 12-tungstophosphoric acid (H(3)PW(12)O(40), abbreviated as HPW or PWA)-silica mesoporous nanocomposite was synthesized through a facile one-step self-assembly between the positively charged silica precursor and negatively charged PW(12)O(40)(3-) species. The self-assembled HPW-silica nanocomposites were characterized by small-angle XRD, TEM, nitrogen adsorption-desorption isotherms, ion exchange capacity, proton conductivity and solid-state (31)P NMR. The results show that highly ordered and uniform nanoarrays with long-range order are formed when the HPW content in the nanocomposites is equal to or lower than 25 wt%. The mesoporous structures/textures were clearly presented, with nanochannels of 3.2-3.5 nm in diameter. The (31)P NMR results indicates that there are (≡SiOH(2)(+))(H(2)PW(12)O(40)(-)) species in the HPW-silica nanocomposites. A HPW-silica (25/75 w/o) nanocomposite gave an activation energy of 13.0 kJ mol(-1) and proton conductivity of 0.076 S cm(-1) at 100 °C and 100 RH%, and an activation energy of 26.1 kJ mol(-1) and proton conductivity of 0.05 S cm(-1) at 200 °C with no external humidification. A fuel cell based on a 165 μm thick HPW-silica nanocomposite membrane achieved a maximum power output of 128.5 and 112.0 mW cm(-2) for methanol and ethanol fuels, respectively, at 200 °C. The high proton conductivity and good performance demonstrate the excellent water retention capability and great potential of the highly ordered HPW-silica mesoporous nanocomposites as high-temperature proton exchange membranes for direct alcohol fuel cells (DAFCs).

Roles of Chemical Functionality and Pore Curvature in the Design of Nanoporous Proton Conductors

DOE PAGES

Jackson, Grayson L.; Perroni, Dominic V.; Mahanthappa, Mahesh K.

2017-10-03

Nanoporous proton-transporting media are critical components in fuel cells and other electrochemical devices, yet general molecular design criteria for new materials with enhanced performance remain obscure. Aqueous lyotropic liquid crystals (LLCs) comprise a platform for detailed studies of the molecular-level features governing proton transport in monodisperse, water-filled nanopores lined with well-defined chemical functionalities. Here, we report new alkylsulfonic acid LLCs that exhibit H+ conductivities as high as σ = 380 mS/cm at 80°C, which rival those of more acidic, perfluorinated polymers, thus demonstrating that the acidity of the pore functionality is not the sole determinant of proton transport. Direct experimentalmore » comparisons of LLCs with convex and concave nanopores of similar dimensions indicate that H+ conductivities therein sensitively depend on the hydration state of the acid functionalities and the pore curvature. These experiments suggest that judicious manipulation of pore curvature provides a new means for optimizing the activities of proton-exchange membranes and nanoporous solid acid catalysts.« less

Synthesis and characterization of sulfonate polystyrene-lignosulfonate-alumina (SPS-LS-Al{sub 2}O{sub 3}) polyblends as electrolyte membranes for fuel cell

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gonggo, Siang Tandi, E-mail: standigonggo@yahoo.com

2015-09-30

The new type of electrolyte membrane materials has been prepared by blend sulfonated polystyrene (SPS), lignosulfonate (LS), and alumina (SPS-LS-Al{sub 2}O{sub 3}) by casting polymer solution. The resulting polymer electrolyte membranes were then characterized by functional groups analysis, mechanical properties, water uptake, ion exchange capacity, and proton conductivity. SPS-LS-Al{sub 2}O{sub 3} membranes with alumina composition various have been proven qualitatively by analysis of functional groups. Increasing the Al{sub 2}O{sub 3} ratio resulted in higher ion exchange capacity (IEC), mechanical strength and proton conductivity, but water uptake decreased. The SPS-LS-Al{sub 2}O{sub 3} blend showed higher proton conductivity than Nafion 117.

Proton transfer in organic scaffolds

NASA Astrophysics Data System (ADS)

Basak, Dipankar

This dissertation focuses on the fundamental understanding of the proton transfer process and translating the knowledge into design/development of new organic materials for efficient non-aqueous proton transport. For example, what controls the shuttling of a proton between two basic sites? a) Distance between two groups? or b) the basicity? c) What is the impact of protonation on molecular conformation when the basic sites are attached to rigid scaffolds? For this purpose, we developed several tunable proton sponges and studied proton transfer in these scaffolds theoretically as well as experimentally. Next we moved our attention to understand long-range proton conduction or proton transport. We introduced liquid crystalline (LC) proton conductor based on triphenylene molecule and established that activation energy barrier for proton transport is lower in the LC phase compared to the crystalline phase. Furthermore, we investigated the impact of several critical factors: the choice of the proton transferring groups, mobility of the charge carriers, intrinsic vs. extrinsic charge carrier concentrations and the molecular architectures on long-range proton transport. The outcome of this research will lead to a deeper understanding of non-aqueous proton transfer process and aid the design of next generation proton exchange membrane (PEM) for fuel cell.

Pendant dual sulfonated poly(arylene ether ketone) proton exchange membranes for fuel cell application

NASA Astrophysics Data System (ADS)

Nguyen, Minh Dat Thinh; Yang, Sungwoo; Kim, Dukjoon

2016-10-01

Poly(arylene ether ketone) (PAEK) possessing carboxylic groups at the pendant position is synthesized, and the substitution degree of pendant carboxylic groups is controlled by adjusting the ratio of 4,4-bis(4-hydroxyphenyl)valeric acid and 2,2-bis(4-hydroxyphenyl)propane. Dual sulfonated 3,3-diphenylpropylamine (SDPA) is grafted onto PAEK as a proton-conducting moiety via the amidation reaction with carboxylic groups. The transparent and flexible membranes with different degrees of sulfonation are fabricated so that we can test and compare their structure and properties with a commercial Nafion® 115 membrane for PEMFC applications. All prepared PAEK-SDPA membranes exhibit good oxidative and hydrolytic stability from Fenton's and high temperature water immersion test. SAXS analysis illustrates an excellent phase separation between the hydrophobic backbone and hydrophilic pendant groups, resulting in big ionic clusters. The proton conductivity was measured at different relative humidity, and its behavior was analyzed by hydration number of the membrane. Among a series of membranes, some samples (including B20V80-SDPA) show not only higher proton conductivity, but also higher integrated cell performance than those of Nafion® 115 at 100% relative humidity, and thus we expect these to be good candidate membranes for proton exchange membrane fuel cells (PEMFCs).

Novel proton exchange membranes based on structure-optimized poly(ether ether ketone ketone)s and nanocrystalline cellulose

NASA Astrophysics Data System (ADS)

Ni, Chuangjiang; Wei, Yingcong; Zhao, Qi; Liu, Baijun; Sun, Zhaoyan; Gu, Yan; Zhang, Mingyao; Hu, Wei

2018-03-01

Two sulfonated fluorenyl-containing poly(ether ether ketone ketone)s (SFPEEKKs) were synthesized as the matrix of composite proton exchange membranes by directly sulfonating copolymer precursors comprising non-sulfonatable fluorinated segments and sulfonatable fluorenyl-containing segments. Surface-modified nanocrystalline cellulose (NCC) was produced as the "performance-enhancing" filler by treating the microcrystalline cellulose with acid. Two families of SFPEEKK/NCC nanocomposite membranes with various NCC contents were prepared via a solution-casting procedure. Results revealed that the insertion of NCC at a suitable ratio could greatly enhance the proton conductivity of the pristine membranes. For example, the proton conductivity of SFPEEKK-60/NCC-4 (SFPEEKK with 60% fluorenyl segments in the repeating unit, and inserted with 4% NCC) composite membrane was as high as 0.245 S cm-1 at 90 °C, which was 61.2% higher than that of the corresponding pure SFPEEKK-60 membrane. This effect could be attributed to the formation of hydrogen bond networks and proton conduction paths through the interaction between -SO3H/-OH groups on the surface of NCC particles and -SO3H groups on the SFPEEKK backbones. Furthermore, the chemically modified NCC filler and the optimized chemical structure of the SFPEEKK matrix also provided good dimensional stability and mechanical properties of the obtained nanocomposites. In conclusion, these novel nanocomposites can be promising proton exchange membranes for fuel cells at moderate temperatures.

Electrolyte membrane, methods of manufacture thereof and articles comprising the same

DOEpatents

Tamaki, Ryo [Santa Clarita, CA; Rice, Steven Thomas [Scotia, NY; Yeager, Gary William [Rexford, NY

2012-06-12

Disclosed herein is a method of forming an electrolyte membrane comprising forming a mixture; the mixture comprising a polyhydroxy compound, an aromatic polyhalide compound and an alkali metal hydroxide; disposing the mixture on a porous substrate; reacting the mixture to form a proton conductor; and crosslinking the proton conductor to form a cross-linked proton-conducting network. Disclosed herein too is an article comprising a porous substrate; and a crosslinked proton conductor disposed on the porous substrate.

Self-assembled one dimensional functionalized metal-organic nanotubes (MONTs) for proton conduction.

PubMed

Panda, Tamas; Kundu, Tanay; Banerjee, Rahul

2012-06-04

Two self-assembled isostructural functionalized metal-organic nanotubes have been synthesized using 5-triazole isophthalic acid (5-TIA) with In(III) and Cd(II). In- and Cd-5TIA possess one-dimensional (1D) nanotubular architecture and show proton conductivity along regular 1D channels, measured as 5.35 × 10(-5) and 3.61 × 10(-3) S cm(-1) respectively.

Multi-block sulfonated poly(phenylene) copolymer proton exchange membranes

DOEpatents

Fujimoto, Cy H [Albuquerque, NM; Hibbs, Michael [Albuquerque, NM; Ambrosini, Andrea [Albuquerque, NM

2012-02-07

Improved multi-block sulfonated poly(phenylene) copolymer compositions, methods of making the same, and their use as proton exchange membranes (PEM) in hydrogen fuel cells, direct methanol fuel cells, in electrode casting solutions and electrodes. The multi-block architecture has defined, controllable hydrophobic and hydrophilic segments. These improved membranes have better ion transport (proton conductivity) and water swelling properties.

High Temperature Protonic Conductors

NASA Technical Reports Server (NTRS)

Dynys, Fred; Berger, Marie-Helen; Sayir, Ali

2007-01-01

High Temperature Protonic Conductors (HTPC) with the perovskite structure are envisioned for electrochemical membrane applications such as H2 separation, H2 sensors and fuel cells. Successive membrane commercialization is dependent upon addressing issues with H2 permeation rate and environmental stability with CO2 and H2O. HTPC membranes are conventionally fabricated by solid-state sintering. Grain boundaries and the presence of intergranular second phases reduce the proton mobility by orders of magnitude than the bulk crystalline grain. To enhanced protonic mobility, alternative processing routes were evaluated. A laser melt modulation (LMM) process was utilized to fabricate bulk samples, while pulsed laser deposition (PLD) was utilized to fabricate thin film membranes . Sr3Ca(1+x)Nb(2-x)O9 and SrCe(1-x)Y(x)O3 bulk samples were fabricated by LMM. Thin film BaCe(0.85)Y(0.15)O3 membranes were fabricated by PLD on porous substrates. Electron microscopy with chemical mapping was done to characterize the resultant microstructures. High temperature protonic conduction was measured by impedance spectroscopy in wet air or H2 environments. The results demonstrate the advantage of thin film membranes to thick membranes but also reveal the negative impact of defects or nanoscale domains on protonic conductivity.

Hydrogen bonding as the origin of the switching behavior in dithiolated phenylene-vinylene oligomers

NASA Astrophysics Data System (ADS)

Obodo, J. T.; Gkionis, K.; Rungger, I.; Sanvito, S.; Schwingenschlögl, U.

2013-08-01

We investigate theoretically the switching behavior of a dithiolated phenylene-vinylene oligomer sandwiched between Au(111) electrodes using self-interaction corrected density-functional theory combined with the nonequilibrium Green's-function method for quantum transport. The molecule presents a configurational bistability, which can be exploited in constructing molecular memories, switches, and sensors. We find that protonation of the terminating thiol groups is at the origin of the change in conductance. H bonding at the thiol group weakens the S-Au bond and reduces by about one order of magnitude the transmission coefficient at the Fermi level, and thus the linear response conductance. Furthermore, protonation downshifts in energy the position of the highest occupied molecular orbital, so that the current of the protonated species is lower than that of the unprotonated one along the entire bias range investigated, from -1.5 to 1.5 V. A second protonation at the opposite thiol group has only minor effects and no further drastic reduction in transmission takes place. Our results allow us to re-interpret the experimental data originally attributing the conductance reduction to H dissociation.

Mordenite/Nafion and analcime/Nafion composite membranes prepared by spray method for improved direct methanol fuel cell performance

NASA Astrophysics Data System (ADS)

Prapainainar, Paweena; Du, Zehui; Kongkachuichay, Paisan; Holmes, Stuart M.; Prapainainar, Chaiwat

2017-11-01

The aim of this work was to improve proton exchange membranes (PEMs) used in direct methanol fuel cells (DMFCs). A membrane with a high proton conductivity and low methanol permeability was required. Zeolite filler in Nafion (NF matrix) composite membranes were prepared using two types of zeolite, mordenite (MOR) and analcime (ANA). Spray method was used to prepare the composite membranes, and properties of the membranes were investigated: mechanical properties, solubility, water and methanol uptake, ion-exchange capacity (IEC), proton conductivity, methanol permeability, and DMFC performance. It was found that MOR filler showed higher performance than ANA. The MOR/Nafion composite membrane gave better properties than ANA/Nafion composite membrane, including a higher proton conductivity and a methanol permeability that was 2-3 times lower. The highest DMFC performance (10.75 mW cm-2) was obtained at 70 °C and with 2 M methanol, with a value 1.5 times higher than that of ANA/Nafion composite membrane and two times higher than that of commercial Nafion 117 (NF 117).

Characteristics of proton beams and secondary neutrons arising from two different beam nozzles

NASA Astrophysics Data System (ADS)

Choi, Yeon-Gyeong; Kim, Yu-Seok

2015-10-01

A tandem or a Van de Graaff accelerator with an energy of 3 MeV is typically used for Proton Induced X-ray Emission (PIXE) analysis. In this study, the beam line design used in the PIXE analysis, instead of the typical low-energy accelerator, was used to increase the production of isotopes from a 13-MeV cyclotron. For the PIXE analysis, the proton beam should be focused at the target through a nozzle after degrading the proton beams energy from 13 MeV to 3 MeV by using an energy degrader. Previous studies have been conducted to determine the most appropriate material for and the thickness of the energy degrader. From the energy distribution of the degraded proton beam and the neutron occurrence rate at the degrader, an aluminum nozzle of X thickness was determined to be the most appropriate nozzle construction. Neutrons are created by the collision of 3-MeV protons in the nozzle after passage through the energy degrader. In addition, a proton beam of sufficient intensity is required for a non-destructive PIXE analysis. Therefore, if nozzle design is to be optimized, the number of neutrons that arise from the collision of protons inside the nozzle, as well as the track direction of the generated secondary neutrons, must be considered, with the primary aim of ensuring that a sufficient number of protons pass through the nozzle as a direct beam. A number of laboratories are currently conducting research related to the design of nozzles used in accelerator fields, mostly medical fields. This paper presents a comparative analysis of two typical nozzle shapes in order to minimize the loss of protons and the generation of secondary neutrons. The neutron occurrence rate and the number of protons that pass through the nozzle were analyzed by using a Particle and Heavy Ion Transport code System (PHITS) program in order to identify the nozzle that generated the strongest proton beam.

High resolution Cerenkov light imaging of induced positron distribution in proton therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamamoto, Seiichi, E-mail: s-yama@met.nagoya-u.ac.jp; Fujii, Kento; Morishita, Yuki

2014-11-01

Purpose: In proton therapy, imaging of the positron distribution produced by fragmentation during or soon after proton irradiation is a useful method to monitor the proton range. Although positron emission tomography (PET) is typically used for this imaging, its spatial resolution is limited. Cerenkov light imaging is a new molecular imaging technology that detects the visible photons that are produced from high-speed electrons using a high sensitivity optical camera. Because its inherent spatial resolution is much higher than PET, the authors can measure more precise information of the proton-induced positron distribution with Cerenkov light imaging technology. For this purpose, theymore » conducted Cerenkov light imaging of induced positron distribution in proton therapy. Methods: First, the authors evaluated the spatial resolution of our Cerenkov light imaging system with a {sup 22}Na point source for the actual imaging setup. Then the transparent acrylic phantoms (100 × 100 × 100 mm{sup 3}) were irradiated with two different proton energies using a spot scanning proton therapy system. Cerenkov light imaging of each phantom was conducted using a high sensitivity electron multiplied charge coupled device (EM-CCD) camera. Results: The Cerenkov light’s spatial resolution for the setup was 0.76 ± 0.6 mm FWHM. They obtained high resolution Cerenkov light images of the positron distributions in the phantoms for two different proton energies and made fused images of the reference images and the Cerenkov light images. The depths of the positron distribution in the phantoms from the Cerenkov light images were almost identical to the simulation results. The decay curves derived from the region-of-interests (ROIs) set on the Cerenkov light images revealed that Cerenkov light images can be used for estimating the half-life of the radionuclide components of positrons. Conclusions: High resolution Cerenkov light imaging of proton-induced positron distribution was possible. The authors conclude that Cerenkov light imaging of proton-induced positron is promising for proton therapy.« less

SU-F-T-140: Assessment of the Proton Boron Fusion Reaction for Practical Radiation Therapy Applications Using MCNP6

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adam, D; Bednarz, B

Purpose: The proton boron fusion reaction is a reaction that describes the creation of three alpha particles as the result of the interaction of a proton incident upon a 11B target. Theoretically, the proton boron fusion reaction is a desirable reaction for radiation therapy applications in that, with the appropriate boron delivery agent, it could potentially combine the localized dose delivery protons exhibit (Bragg peak) and the local deposition of high LET alpha particles in cancerous sites. Previous efforts have shown significant dose enhancement using the proton boron fusion reaction; the overarching purpose of this work is an attempt tomore » validate previous Monte Carlo results of the proton boron fusion reaction. Methods: The proton boron fusion reaction, 11B(p, 3α), is investigated using MCNP6 to assess the viability for potential use in radiation therapy. Simple simulations of a proton pencil beam incident upon both a water phantom and a water phantom with an axial region containing 100ppm boron were modeled using MCNP6 in order to determine the extent of the impact boron had upon the calculated energy deposition. Results: The maximum dose increase calculated was 0.026% for the incident 250 MeV proton beam scenario. The MCNP simulations performed demonstrated that the proton boron fusion reaction rate at clinically relevant boron concentrations was too small in order to have any measurable impact on the absorbed dose. Conclusion: For all MCNP6 simulations conducted, the increase of absorbed dose of a simple water phantom due to the 11B(p, 3α) reaction was found to be inconsequential. In addition, it was determined that there are no good evaluations of the 11B(p, 3α) reaction for use in MCNPX/6 and further work should be conducted in cross section evaluations in order to definitively evaluate the feasibility of the proton boron fusion reaction for use in radiation therapy applications.« less

Development of a low-energy x-ray camera for the imaging of secondary electron bremsstrahlung x-ray emitted during proton irradiation for range estimation.

PubMed

Ando, Koki; Yamaguchi, Mitsutaka; Yamamoto, Seiichi; Toshito, Toshiyuki; Kawachi, Naoki

2017-06-21

Imaging of secondary electron bremsstrahlung x-ray emitted during proton irradiation is a possible method for measurement of the proton beam distribution in phantom. However, it is not clear that the method is used for range estimation of protons. For this purpose, we developed a low-energy x-ray camera and conducted imaging of the bremsstrahlung x-ray produced during irradiation of proton beams. We used a 20 mm  ×  20 mm  ×  1 mm finely grooved GAGG scintillator that was optically coupled to a one-inch square high quantum efficiency (HQE)-type position-sensitive photomultiplier tube to form an imaging detector. The imaging detector was encased in a 2 cm-thick tungsten container, and a pinhole collimator was attached to its camera head. After performance of the camera was evaluated, secondary electron bremsstrahlung x-ray imaging was conducted during irradiation of the proton beams for three different proton energies, and the results were compared with Monte Carlo simulation as well as calculated value. The system spatial resolution and sensitivity of the developed x-ray camera with 1.5 mm-diameter pinhole collimator were estimated to be 32 mm FWHM and 5.2  ×  10 -7 for ~35 keV x-ray photons at 100 cm from the collimator surface, respectively. We could image the proton beam tracks by measuring the secondary electron bremsstrahlung x-ray during irradiation of the proton beams, and the ranges for different proton energies could be estimated from the images. The measured ranges from the images were well matched with the Monte Carlo simulation, and slightly smaller than the calculated values. We confirmed that the imaging of the secondary electron bremsstrahlung x-ray emitted during proton irradiation with the developed x-ray camera has the potential to be a new tool for proton range estimations.

Parasitic Currents Caused by Different Ionic and Electronic Conductivities in Fuel Cell Anodes.

PubMed

Schalenbach, Maximilian; Zillgitt, Marcel; Maier, Wiebke; Stolten, Detlef

2015-07-29

The electrodes in fuel cells simultaneously realize electric and ionic conductivity. In the case of acidic polymer electrolytes, the electrodes are typically made of composites of carbon-supported catalyst and Nafion polymer electrolyte binder. In this study, the interaction of the proton conduction, the electron conduction, and the electrochemical hydrogen conversion in such composite electrode materials was examined. Exposed to a hydrogen atmosphere, these composites displayed up to 10-fold smaller resistivities for the proton conduction than that of Nafion membranes. This effect was ascribed to the simultaneously occurring electrochemical hydrogen oxidation and evolution inside the composite samples, which are driven by different proton and electron resistivities. The parasitic electrochemical currents resulting were postulated to occur in the anode of fuel cells with polymer, solid oxide, or liquid alkaline electrolytes, when the ohmic drop of the ion conduction in the anode is higher with the anodic kinetic overvoltage (as illustrated in the graphical abstract). In this case, the parasitic electrochemical currents increase the anodic kinetic overpotential and the ohmic drop in the anode. Thinner fuel cell anodes with smaller ohmic drops for the ion conduction may reduce the parasitic electrochemical currents.

Conductivity and spectroscopic investigation of bis(trifluoromethanesulfonyl)imide solution in ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide.

PubMed

Yu, Lei; Pizio, Benjamin S; Vaden, Timothy D

2012-06-07

Protic ionic liquids (PILs) are promising alternatives to water for swelling Nafion as a fuel cell proton exchange membrane (PEM). PILs can significantly improve the high-temperature performance of a PEM. The proton dissociation and solvation mechanisms in a PIL, which are keys to understanding the proton transportation and conductivity, have not been fully explored. In this paper, we used FTIR, Raman, and electronic spectroscopy with computational simulation techniques to explore the spectroscopic properties of bis(trifluoromethanesulfonyl)imide (HTFSI) solutions in 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMITFSI) ionic liquid at concentrations from ∼0.1 to as high as ∼1.0 M. Solution conductivities were measured at room temperature and elevated temperatures up to ∼65 °C. The solution structure and properties depend on the concentration of HTFSI. At lower concentration, around 0.1 M, the HTFSI solution has higher conductivity than pure BMITFSI. However, the conductivity decreases when the concentration increases from 0.1 to 1.0 M. Temperature-dependent conductivities followed the Vogel-Fulcher-Tamman equation at all concentrations. Conductivity and spectroscopy results elucidate the complicated ionization and solvation mechanism of HTFSI in BMITFSI solutions. Raman spectroscopy and density functional theory (DFT) calculations are consistent with the complete ionization of HTFSI to generate solvated H(+) at low concentrations. FTIR, Raman, and electronic spectroscopic results as well as DFT computational simulation indicated that when the concentration is as high as 1.0 M, a significant amount of TFSI(-) is protonated, most likely at the imide nitrogen.

Stable transport in proton driven fast ignition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bret, A.

2009-09-15

Proton beam transport in the context of proton driven fast ignition is usually assumed to be stable due to proton high inertia, but an analytical analysis of the process is still lacking. The stability of a charge and current neutralized proton beam passing through a plasma is therefore conducted here, for typical proton driven fast ignition parameters. In the cold regime, two fast growing modes are found, with an inverse growth rate much smaller than the beam time of flight to the target core. The stability issue is thus not so obvious, and kinetic effects are investigated. One unstable modemore » is found stabilized by the background plasma proton and electron temperatures. The second mode is also damped, providing the proton beam thermal spread is larger than {approx}10 keV. In fusion conditions, the beam propagation should therefore be stable.« less

Coarse-grained model of water diffusion and proton conductivity in hydrated polyelectrolyte membrane

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Ming-Tsung; Vishnyakov, Aleksey; Neimark, Alexander V., E-mail: aneimark@rutgers.edu

2016-01-07

Using dissipative particle dynamics (DPD), we simulate nanoscale segregation, water diffusion, and proton conductivity in hydrated sulfonated polystyrene (sPS). We employ a novel model [Lee et al. J. Chem. Theory Comput. 11(9), 4395-4403 (2015)] that incorporates protonation/deprotonation equilibria into DPD simulations. The polymer and water are modeled by coarse-grained beads interacting via short-range soft repulsion and smeared charge electrostatic potentials. The proton is introduced as a separate charged bead that forms dissociable Morse bonds with the base beads representing water and sulfonate anions. Morse bond formation and breakup artificially mimics the Grotthuss mechanism of proton hopping between the bases. Themore » DPD model is parameterized by matching the proton mobility in bulk water, dissociation constant of benzenesulfonic acid, and liquid-liquid equilibrium of water-ethylbenzene solutions. The DPD simulations semi-quantitatively predict nanoscale segregation in the hydrated sPS into hydrophobic and hydrophilic subphases, water self-diffusion, and proton mobility. As the hydration level increases, the hydrophilic subphase exhibits a percolation transition from isolated water clusters to a 3D network. The analysis of hydrophilic subphase connectivity and water diffusion demonstrates the importance of the dynamic percolation effect of formation and breakup of temporary junctions between water clusters. The proposed DPD model qualitatively predicts the ratio of proton to water self-diffusion and its dependence on the hydration level that is in reasonable agreement with experiments.« less

Role of Water in Proton-Hydroxide Conductance Across Membranes

DTIC Science & Technology

1988-06-28

a~a,:v %~ ’ diffusion , rather than hopping along water wires, and there should be little or no deuterium effect. References Bangham , A.D...CONTRACT TITLE: Role of water in proton-hydroxide conductance across model and biological membranes. START DATE: October 1, 1987 RESEARCH OBJECTIVE: To...hypothesis of Bangham and Mason (1980) who suggested that general anesthetics might introduce defects into bilayers of synaptic vesicle membranes which lead

Dense proton injection into phosphate glasses using corona discharge treatment

NASA Astrophysics Data System (ADS)

Kinoshita, Takuya; Miyazaki, Atsushi; Kawaguchi, Keiga; Sakai, Daisuke; Yamaguchi, Takuya; Omata, Takahisa; Ishiyama, Tomohiro; Fujioka, Masaya; Kaiju, Hideo; Nishii, Junji

2018-01-01

Sodium ions in 25NaO1/2-6LaO3/2-6GeO2-63PO5/2 (mol%) glasses were substituted with protons using corona discharge treatment (CDT) under a H2 atmosphere. The substitution of sodium ion to proton proceeded from the anode side to the cathode side with constant current flow during the CDT. A crystalline free and transparent glass plate of 0.3 mm thickness was obtained after CDT for 96 h. The maximum decrease rate from sodium ion to proton was 78 ± 10%. The proton conductivity of 8.5 × 10-4 S/cm was attained at 400 °C.

The efficiency of cellular energy transduction and its implications for obesity.

PubMed

Harper, Mary-Ellen; Green, Katherine; Brand, Martin D

2008-01-01

We assess the existence, mechanism, and functions of less-than-maximal coupling efficiency of mitochondrial oxidative phosphorylation and its potential as a target for future antiobesity interventions. Coupling efficiency is the proportion of oxygen consumption used to make adenosine triphosphate (ATP) and do useful work. High coupling efficiency may lead to fat deposition; low coupling efficiency to a decrease in fat stores. We review obligatory and facultative energy expenditure and the role of a futile cycle of proton pumping and proton leak across the mitochondrial inner membrane in dissipating energy. Basal proton conductance is catalyzed primarily by the adenine nucleotide translocase but can be mimicked by chemical uncouplers. Inducible proton conductance is catalyzed by specific uncoupling proteins. We discuss the opportunities and pitfalls of targeting these processes as a treatment for obesity by decreasing coupling efficiency and increasing energy expenditure, either directly or through central mechanisms of energy homeostasis.

Chitin nanowhisker-supported sulfonated poly(ether sulfone) proton exchange for fuel cell applications.

PubMed

Zhang, Chan; Zhuang, Xupin; Li, Xiaojie; Wang, Wei; Cheng, Bowen; Kang, Weimin; Cai, Zhanjun; Li, Mengqin

2016-04-20

To balance the relationship among proton conductivity and mechanic strength of sulfonated poly(ether sulfone) (SPES) membrane, chitin nanowhisker-supported nanocomposite membranes were prepared by incorporating whiskers into SPES. The as-prepared chitin whiskers were prepared by 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) mediated oxidation of α-chitin from crab shells. The structure and properties of the composite membranes were examined as proton exchange membrane (PEM). Results showed that chitin nanowhiskers were dispersed incompactly in the SPES matrix. Thermal stability, mechanical properties, water uptake and proton conductivity of the nanocomposite films were improved from those of the pure SPES film with increasing whisker content, which ascribed to strong interactions between whiskers and between SPES molecules and chitin whiskers via hydrogen bonding. These indicated that composition of filler and matrix got good properties and whisker-supported membranes are promising materials for PEM. Copyright © 2015 Elsevier Ltd. All rights reserved.

Chitosan/silica coated carbon nanotubes composite proton exchange membranes for fuel cell applications.

PubMed

Liu, Hai; Gong, Chunli; Wang, Jie; Liu, Xiaoyan; Liu, Huanli; Cheng, Fan; Wang, Guangjin; Zheng, Genwen; Qin, Caiqin; Wen, Sheng

2016-01-20

Silica-coated carbon nanotubes (SCNTs), which were obtained by a simple sol-gel method, were utilized in preparation of chitosan/SCNTs (CS/SCNTs) composite membranes. The thermal and oxidative stability, morphology, mechanical properties, water uptake and proton conductivity of CS/SCNTs composite membranes were investigated. The insulated and hydrophilic silica layer coated on CNTs eliminates the risk of electronic short-circuiting and enhances the interaction between SCNTs and chitosan to ensure the homogenous dispersion of SCNTs, although the water uptake of CS/SCNTs membranes is reduced owing to the decrease of the effective number of the amino functional groups of chitosan. The CS/SCNTs composite membranes are superior to the pure CS membrane in thermal and oxidative stability, mechanical properties and proton conductivity. The results of this study suggest that CS/SCNTs composite membranes exhibit promising potential for practical application in proton exchange membranes. Copyright © 2015 Elsevier Ltd. All rights reserved.

Response functions of Fuji imaging plates to monoenergetic protons in the energy range 0.6-3.2 MeV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bonnet, T.; Denis-Petit, D.; Gobet, F.

2013-01-15

We have measured the responses of Fuji MS, SR, and TR imaging plates (IPs) to protons with energies ranging from 0.6 to 3.2 MeV. Monoenergetic protons were produced with the 3.5 MV AIFIRA (Applications Interdisciplinaires de Faisceaux d'Ions en Region Aquitaine) accelerator at the Centre d'Etudes Nucleaires de Bordeaux Gradignan (CENBG). The IPs were irradiated with protons backscattered off a tantalum target. We present the photo-stimulated luminescence response of the IPs together with the fading measurements for these IPs. A method is applied to allow correction of fading effects for variable proton irradiation duration. Using the IP fading corrections, amore » model of the IP response function to protons was developed. The model enables extrapolation of the IP response to protons up to proton energies of 10 MeV. Our work is finally compared to previous works conducted on Fuji TR IP response to protons.« less

Expanding the View of Proton Pumping in Cytochrome c Oxidase through Computer Simulation

PubMed Central

Peng, Yuxing; Voth, Gregory A.

2011-01-01

In cytochrome c oxidase (CcO), a redox-driven proton pump, protons are transported by the Grotthuss shuttling via hydrogen-bonded water molecules and protonatable residues. Proton transport through the D-pathway is a complicated process that is highly sensitive to alterations in the amino acids or the solvation structure in the channel, both of which can inhibit proton pumping and enzymatic activity. Simulations of proton transport in the hydrophobic cavity showed a clear redox state dependence. To study the mechanism of proton pumping in CcO, multi-state empirical valence bond (MS-EVB) simulations have been conducted, focusing on the proton transport through the D-pathway and the hydrophobic cavity next to the binuclear center. The hydration structures, transport pathways, effects of residues, and free energy surfaces of proton transport were revealed in these MS-EVB simulations. The mechanistic insight gained from them is herein reviewed and placed in context for future studies. PMID:22178790

Investigation of bio polymer electrolyte based on cellulose acetate-ammonium nitrate for potential use in electrochemical devices.

PubMed

Monisha, S; Mathavan, T; Selvasekarapandian, S; Milton Franklin Benial, A; Aristatil, G; Mani, N; Premalatha, M; Vinoth Pandi, D

2017-02-10

Proton conducting materials create prime interest in electro chemical device development. Present work has been carried out to design environment friendly new biopolymer electrolytes (BPEs) using cellulose acetate (CA) complex with different concentrations of ammonium nitrate (NH 4 NO 3 ), which have been prepared as film and characterized. The 50mol% CA and 50mol% NH 4 NO 3 complex has highest ionic conductivity (1.02×10 -3 Scm -1 ). Differential scanning calorimetry shows the changes in glass transition temperature depends on salt concentration. Structural analysis indicates that the highest ionic conductivity complex exhibits more amorphous nature. Vibrational analysis confirms the complex formation, which has been validated theoretically by Gaussian 09 software. Conducting element in the BPEs has been predicted. Primary proton battery and proton exchange membrane fuel cell have been developed for highest ionic conductivity complex. Output voltage and power performance has been compared for single fuel cell application, which manifests the present BPE holds promise application in electrochemical devices. Copyright © 2016 Elsevier Ltd. All rights reserved.

Water-Stable Nanoporous Polymer Films with Excellent Proton Conductivity.

PubMed

Wang, Zhengbang; Liang, Cong; Tang, Haolin; Grosjean, Sylvain; Shahnas, Artak; Lahann, Joerg; Bräse, Stefan; Wöll, Christof

2018-03-01

Achieving high values for proton conductivity in a material critically depends on providing hopping sites arranged in a regular fashion. Record values reported for regular, molecular crystals cannot yet be reached by technologically relevant systems, and the best values measured for polymer membranes suited for integration into devices are almost two orders of magnitude lower. Here, an alternative polymer membrane synthesis strategy based on the chemical modification of surface-mounted, monolithic, crystalline metal-organic framework thin films is demonstrated. Due to chemical crosslinking and subsequent removal of metal ions, these surface-mounted gels (SURGELs) are found to exhibit high proton conductivity (0.1 S cm -1 at 30 °C and 100% RH (relative humidity). These record values are attributed to the highly ordered polymer network structure containing regularly spaced carboxylic acid side groups. These covalently bound organic frameworks outperform conventional, ion-conductive polymers with regard to ion conductivity and water stability. Pronounced water-induced swelling, which causes severe mechanical instabilities in commercial membranes, is not observed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Microstructured Electrolyte Membranes to Improve Fuel Cell Performance

NASA Astrophysics Data System (ADS)

Wei, Xue

Fuel cells, with the advantages of high efficiency, low greenhouse gas emission, and long lifetime are a promising technology for both portable power and stationary power sources. The development of efficient electrolyte membranes with high ionic conductivity, good mechanical durability and dense structure at low cost remains a challenge to the commercialization of fuel cells. This thesis focuses on exploring novel composite polymer membranes and ceramic electrolytes with the microstructure engineered to improve performance in direct methanol fuel cells (DMFCs) and solid oxide fuel cells (SOFCs), respectively. Polymer/particle composite membranes hold promise to meet the demands of DMFCs at lower cost. The structure of composite membranes was controlled by aligning proton conducting particles across the membrane thickness under an applied electric field. The field-induced structural changes caused the membranes to display an enhanced water uptake, proton conductivity, and methanol permeability in comparison to membranes prepared without an applied field. Although both methanol permeability and proton conductivity are enhanced by the applied field, the permeability increase is relatively lower than the proton conductivity improvement, which results in enhanced proton/methanol selectivity and improved DMFC performance. Apatite ceramics are a new class of fast ion conductors being studied as alternative SOFC electrolytes in the intermediate temperature range. An electrochemical/hydrothermal deposition method was developed to grow fully dense apatite membranes containing well-developed crystals with c-axis alignment to promote ion conductivity. Hydroxyapatite seed crystals were first deposited onto a metal substrate electrochemically. Subsequent ion substitution during the hydrothermal growth process promoted the formation of dense, fully crystalline films with microstructure optimal for ion transport. The deposition parameters were systematically investigated, such as reactant type, reagent concentration, solution pH, and reaction time. Dense apatite films were formed on palladium substrates that can serve as intermediate temperature fuel cell anodes. The novel apatite membrane structure is promising for fuel cell applications, as well as in improving the biocompatibility of orthopedic implants when coated on stainless steel or titanium substrates.

Novel Composite Proton Exchange Membrane with Connected Long-Range Ionic Nanochannels Constructed via Exfoliated Nafion-Boron Nitride Nanocomposite.

PubMed

Jia, Wei; Tang, Beibei; Wu, Peiyi

2017-05-03

Nafion-boron nitride (NBN) nanocomposites with a Nafion-functionalized periphery are prepared via a convenient and ecofriendly Nafion-assisted water-phase exfoliation method. Nafion and the boron nitride nanosheet present strong interactions in the NBN nanocomposite. Then the NBN nanocomposites were blended with Nafion to prepare NBN Nafion composite proton exchange membranes (PEMs). NBN nanocomposites show good dispersibility and have a noticeable impact on the aggregation structure of the Nafion matrix. Connected long-range ionic nanochannels containing exaggerated (-SO 3 - ) n ionic clusters are constructed during the membrane-forming process via the hydrophilic and H-bonding interactions between NBN nanocomposites and Nafion matrix. The addition of NBN nanocomposites with sulfonic groups also provides additional proton transportation spots and enhances the water uptake of the composite PEMs. The proton conductivity of the NBN Nafion composite PEMs is significantly increased under various conditions relative to that of recast Nafion. At 80 °C-95% relative humidity, the proton conductivity of 0.5 NBN Nafion is 0.33 S·cm -1 , 6 times that of recast Nafion under the same conditions.

Transport properties of proton-exchange membranes: Effect of supercritical-fluid processing and chemical functionality

NASA Astrophysics Data System (ADS)

Pulido Ayazo

NafionRTM membranes commonly used in direct methanol fuel cells (DMFC), are tipically limited by high methanol permeability (also known as the cross-over limitation). These membranes have phase segregated sulfonated ionic domains in a perfluorinated backbone, which makes processing challenging and limited by phase equilibria considerations. This study used supercritical fluids (SCFs) as a processing alternative, since the gas-like mass transport properties of SCFs allow a better penetration into the membranes and the use of polar co-solvents influenced their morphology, fine-tuning the physical and transport properties in the membrane. Measurements of methanol permeability and proton conductivity were performed to the NafionRTM membranes processed with SCFs at 40ºC and 200 bar and the co-solvents as: acetone, tetrahydrofuran (THF), isopropyl alcohol, HPLC-grade water, acetic acid, cyclohexanone. The results obtained for the permeability data were of the order of 10 -8-10-9 cm2/s, two orders of magnitude lower than unprocessed Nafion. Proton conductivity results obtained using AC impedance electrochemical spectroscopy was between 0.02 and 0.09 S/cm, very similar to the unprocessed Nafion. SCF processing with ethanol as co-solvent reduced the methanol permeability by two orders of magnitude, while the proton conductivity was only reduced by 4%. XRD analysis made to the treated samples exhibited a decreasing pattern in the crystallinity, which affects the transport properties of the membrane. Also, SAXS profiles of the Nafion membranes processed were obtained with the goal of determining changes produced by the SCF processing in the hydrophilic domains of the polymer. With the goal of searching for new alternatives in proton exchange membranes (PEMs) triblock copolymer of poly(styrene-isobutylene-styrene) (SIBS) and poly(styrene-isobutylene-styrene) SEBS were studied. These sulfonated tri-block copolymers had lower methanol permeabilities, but also lower proton conductivity, even with blends of these and blends with Nafion membranes. Other alternative studied was the functionalization of the membranes SIBS with metallic cations, which decreased the methanol permeability in the membranes containing the cations Mg2+, Zn2+ and Al 3+, while the proton conductivity was maintained more or less constant. The permeation of methanol vapor was investigated and the behavior through the membranes studied followed a pattern of Fick's Law, while the pattern shown by the permeation in liquid phase was non-Fickian.

Systematic Study of Three-Nucleon System Dynamics in Deuteron-Proton Breakup Reaction

NASA Astrophysics Data System (ADS)

Kozela, A.; Ciepał, I.; Garbacz, M.; Jamróz, B.; Kłos, B.; Kistryn, St.; Khatri, G.; Kuboś, J.; Kulessa, P.; Liptak, A.; Parol, W.; Rusnok, A.; Sȩkowski, P.; Skwira-Chalot, I.; Stephan, E.; Wilczek, A.; Włoch, B.; Zejma, J.

2017-03-01

We report on preliminary results of the first measurement of elastic scattering of protons from deuterons and proton induced deuteron breakup at proton beam energy of 108 MeV conducted at new Cyclotron Center Bronowice IFJ PAN in Kraków. The experiment is aimed at precise determination of the differential cross section for extensive set of kinematical configurations in a wide range of angular acceptance. In the first data taking run the average statistical per-point accuracy of about 5% has been reached.

Structural characteristics of hydrated protons in the conductive channels: effects of confinement and fluorination studied by molecular dynamics simulation.

PubMed

Zhang, Ning; Song, Yuechun; Ruan, Xuehua; Yan, Xiaoming; Liu, Zhao; Shen, Zhuanglin; Wu, Xuemei; He, Gaohong

2016-09-21

The relationship between the proton conductive channel and the hydrated proton structure is of significant importance for understanding the deformed hydrogen bonding network of the confined protons which matches the nanochannel. In general, the structure of hydrated protons in the nanochannel of the proton exchange membrane is affected by several factors. To investigate the independent effect of each factor, it is necessary to eliminate the interference of other factors. In this paper, a one-dimensional carbon nanotube decorated with fluorine was built to investigate the independent effects of nanoscale confinement and fluorination on the structural properties of hydrated protons in the nanochannel using classical molecular dynamics simulation. In order to characterize the structure of hydrated protons confined in the channel, the hydrogen bonding interaction between water and the hydrated protons has been studied according to suitable hydrogen bond criteria. The hydrogen bond criteria were proposed based on the radial distribution function, angle distribution and pair-potential energy distribution. It was found that fluorination leads to an ordered hydrogen bonding structure of the hydrated protons near the channel surface, and confinement weakens the formation of the bifurcated hydrogen bonds in the radial direction. Besides, fluorination lowers the free energy barrier of hydronium along the nanochannel, but slightly increases the barrier for water. This leads to disintegration of the sequential hydrogen bond network in the fluorinated CNTs with small size. In the fluorinated CNTs with large diameter, the lower degree of confinement produces a spiral-like sequential hydrogen bond network with few bifurcated hydrogen bonds in the central region. This structure might promote unidirectional proton transfer along the channel without random movement. This study provides the cooperative effect of confinement dimension and fluorination on the structure and hydrogen bonding of the slightly acidic water in the nanoscale channel.

Quantum Dynamics in Continuum for Proton Transport I: Basic Formulation.

PubMed

Chen, Duan; Wei, Guo-Wei

2013-01-01

Proton transport is one of the most important and interesting phenomena in living cells. The present work proposes a multiscale/multiphysics model for the understanding of the molecular mechanism of proton transport in transmembrane proteins. We describe proton dynamics quantum mechanically via a density functional approach while implicitly model other solvent ions as a dielectric continuum to reduce the number of degrees of freedom. The densities of all other ions in the solvent are assumed to obey the Boltzmann distribution. The impact of protein molecular structure and its charge polarization on the proton transport is considered explicitly at the atomic level. We formulate a total free energy functional to put proton kinetic and potential energies as well as electrostatic energy of all ions on an equal footing. The variational principle is employed to derive nonlinear governing equations for the proton transport system. Generalized Poisson-Boltzmann equation and Kohn-Sham equation are obtained from the variational framework. Theoretical formulations for the proton density and proton conductance are constructed based on fundamental principles. The molecular surface of the channel protein is utilized to split the discrete protein domain and the continuum solvent domain, and facilitate the multiscale discrete/continuum/quantum descriptions. A number of mathematical algorithms, including the Dirichlet to Neumann mapping, matched interface and boundary method, Gummel iteration, and Krylov space techniques are utilized to implement the proposed model in a computationally efficient manner. The Gramicidin A (GA) channel is used to demonstrate the performance of the proposed proton transport model and validate the efficiency of proposed mathematical algorithms. The electrostatic characteristics of the GA channel is analyzed with a wide range of model parameters. The proton conductances are studied over a number of applied voltages and reference concentrations. A comparison with experimental data verifies the present model predictions and validates the proposed model.

Proton transport, water uptake and hydrogen permeability of nanoporous hematite ceramic membranes

NASA Astrophysics Data System (ADS)

Colomer, M. T.

2011-10-01

For the first time, mesoporous acid-free hematite ceramic membranes have been studied as proton conductors. The xerogels after calcination at 300 °C for 1 h were mesoporous, as is mentioned above, with a BET surface area of 130 ± 2 m2 g-1, an average pore diameter of 3.8 nm and a pore volume of 0.149 ± 0.001 cc g-1. A sigmoidal dependence of the conductivity and the water uptake with the RH at a constant temperature was observed. The conductivity of the ceramic membranes increased linearly with temperature for all relative humidities studied. The highest value of proton conductivity was found to be 2.76 × 10-3 S cm-1 at 90 °C and 81% RH. According to the activation energy values, proton migration in this kind of materials could be dominated by the Grotthuss mechanism in the whole range of RH. The low cost and high hydrophilicity of these ceramic membranes make them potential substitutes for perfluorosulfonic polymeric membranes in proton exchange membrane (PEMFCs). In addition, since hydrogen permeability values are in the range of 10-9 to 10-10 mol cm-1 s Pa, in order to fabricate oxide-based PEMs that are capable of keeping streams of H2 and O2 from mixing, a separation layer with pore sizes <2 nm whose pores are filled with water will be needed.

Voltage-gated Proton Channels

PubMed Central

DeCoursey, Thomas E.

2014-01-01

Voltage-gated proton channels, HV1, have vaulted from the realm of the esoteric into the forefront of a central question facing ion channel biophysicists, namely the mechanism by which voltage-dependent gating occurs. This transformation is the result of several factors. Identification of the gene in 2006 revealed that proton channels are homologues of the voltage-sensing domain of most other voltage-gated ion channels. Unique, or at least eccentric, properties of proton channels include dimeric architecture with dual conduction pathways, perfect proton selectivity, a single-channel conductance ~103 smaller than most ion channels, voltage-dependent gating that is strongly modulated by the pH gradient, ΔpH, and potent inhibition by Zn2+ (in many species) but an absence of other potent inhibitors. The recent identification of HV1 in three unicellular marine plankton species has dramatically expanded the phylogenetic family tree. Interest in proton channels in their own right has increased as important physiological roles have been identified in many cells. Proton channels trigger the bioluminescent flash of dinoflagellates, facilitate calcification by coccolithophores, regulate pH-dependent processes in eggs and sperm during fertilization, secrete acid to control the pH of airway fluids, facilitate histamine secretion by basophils, and play a signaling role in facilitating B-cell receptor mediated responses in B lymphocytes. The most elaborate and best-established functions occur in phagocytes, where proton channels optimize the activity of NADPH oxidase, an important producer of reactive oxygen species. Proton efflux mediated by HV1 balances the charge translocated across the membrane by electrons through NADPH oxidase, minimizes changes in cytoplasmic and phagosomal pH, limits osmotic swelling of the phagosome, and provides substrate H+ for the production of H2O2 and HOCl, reactive oxygen species crucial to killing pathogens. PMID:23798303

Development of composite membrane materials for fuel cells

NASA Astrophysics Data System (ADS)

Lebedeva, O. V.; Chesnokova, A. N.; Pozhidaev, Yu N.; Maksimenko, S. D.; Malakhova, E. A.; Raskulova, T. V.

2018-03-01

This study is devoted to the development and investigation of composite membrane materials for fuel cells. Proton conductive membranes consisting of silica and various low- and high-molecular organic compounds have been prepared by the sol-gel method. The synthesized membranes are characterized by proton conductivity (up to 10-2 S/cm), ion-exchange capacity (1.84-3.5 meq/g), thermal stability (260 – 400 °C), and tensile modulus (128 - 322 MPa).

A Water-Stable Proton-Conductive Barium(II)-Organic Framework for Ammonia Sensing at High Humidity.

PubMed

Guo, Kaimeng; Zhao, Lili; Yu, Shihang; Zhou, Wenyan; Li, Zifeng; Li, Gang

2018-06-07

In view of environmental protection and the need for early prediction of major diseases, it is necessary to accurately monitor the change of trace ammonia concentration in air or in exhaled breath. However, the adoption of proton-conductive metal-organic frameworks (MOFs) as smart sensors in this field is limited by a lack of ultrasensitive gas-detecting performance at high relative humidity (RH). Here, the pellet fabrication of a water-stable proton-conductive MOF, Ba( o-CbPhH 2 IDC)(H 2 O) 4 ] n (1) ( o-CbPhH 4 IDC = 2-(2-carboxylphenyl)-1 H-imidazole-4,5-dicarboxylic acid) is reported. The MOF 1 displays enhanced sensitivity and selectivity to NH 3 gas at high RHs (>85%) and 30 °C, and the sensing mechanism is suggested. The electrochemical impedance gas sensor fabricated by MOF 1 is a promising sensor for ammonia at mild temperature and high RHs.

Phosphoric acid functionalized pre-sintered meso-silica for high temperature proton exchange membrane fuel cells.

PubMed

Zeng, Jie; He, Beibei; Lamb, Krystina; De Marco, Roland; Shen, Pei Kang; Jiang, San Ping

2013-05-21

An inorganic proton exchange membrane based on sintered mesoporous silica and phosphoric acid was developed with a high proton conductivity of 0.06 S cm(-1) at 200 °C, achieving an excellent power output of 689 mW cm(-2) in H2 at 190 °C and 200 mW cm(-2) in methanol at 200 °C with no external humidification.

Voltage-gated proton channel in a dinoflagellate

PubMed Central

Smith, Susan M. E.; Morgan, Deri; Musset, Boris; Cherny, Vladimir V.; Place, Allen R.; Hastings, J. Woodland; DeCoursey, Thomas E.

2011-01-01

Fogel and Hastings first hypothesized the existence of voltage-gated proton channels in 1972 in bioluminescent dinoflagellates, where they were thought to trigger the flash by activating luciferase. Proton channel genes were subsequently identified in human, mouse, and Ciona intestinalis, but their existence in dinoflagellates remained unconfirmed. We identified a candidate proton channel gene from a Karlodinium veneficum cDNA library based on homology with known proton channel genes. K. veneficum is a predatory, nonbioluminescent dinoflagellate that produces toxins responsible for fish kills worldwide. Patch clamp studies on the heterologously expressed gene confirm that it codes for a genuine voltage-gated proton channel, kHV1: it is proton-specific and activated by depolarization, its gH–V relationship shifts with changes in external or internal pH, and mutation of the selectivity filter (which we identify as Asp51) results in loss of proton-specific conduction. Indirect evidence suggests that kHV1 is monomeric, unlike other proton channels. Furthermore, kHV1 differs from all known proton channels in activating well negative to the Nernst potential for protons, EH. This unique voltage dependence makes the dinoflagellate proton channel ideally suited to mediate the proton influx postulated to trigger bioluminescence. In contrast to vertebrate proton channels, whose main function is acid extrusion, we propose that proton channels in dinoflagellates have fundamentally different functions of signaling and excitability. PMID:22006335

High temperature polymers for proton exchange membrane fuel cells

NASA Astrophysics Data System (ADS)

Einsla, Brian Russel

Novel proton exchange membranes (PEMs) were investigated that show potential for operating at higher temperatures in both direct methanol (DMFC) and H 2/air PEM fuel cells. The need for thermally stable polymers immediately suggests the possibility of heterocyclic polymers bearing appropriate ion conducting sites. Accordingly, monomers and random disulfonated poly(arylene ether) copolymers containing either naphthalimide, benzoxazole or benzimidazole moieties were synthesized via direct copolymerization. The ion exchange capacity (IEC) was varied by simply changing the ratio of disulfonated monomer to nonsulfonated monomer in the copolymerization step. Water uptake and proton conductivity of cast membranes increased with IEC. The water uptake of these heterocyclic copolymers was lower than that of comparable disulfonated poly(arylene ether) systems, which is a desirable improvement for PEMs. Membrane electrode assemblies were prepared and the initial fuel cell performance of the disulfonated polyimide and polybenzoxazole (PBO) copolymers was very promising at 80°C compared to the state-of-the-art PEM (NafionRTM); nevertheless these membranes became brittle under operating conditions. Several series of poly(arylene ether)s based on disodium-3,3'-disulfonate-4,4 '-dichlorodiphenylsulfone (S-DCDPS) and a benzimidazole-containing bisphenol were synthesized and afforded copolymers with enhanced stability. Selected properties of these membranes were compared to separately prepared miscible blends of disulfonated poly(arylene ether sulfone) copolymers and polybenzimidazole (PBI). Complexation of the sulfonic acid groups with the PBI structure reduced water swelling and proton conductivity. The enhanced proton conductivity of NafionRTM membranes has been proposed to be due to the aggregation of the highly acidic side-chain sulfonic acid sites to form ion channels. A series of side-chain sulfonated poly(arylene ether sulfone) copolymers based on methoxyhydroquinone was synthesized in order to investigate this possible advantage and to couple this with the excellent hydrolytic stability of poly(arylene ether)s. The methoxy groups were deprotected to afford reactive phenolic sites and nucleophilic substitution reactions with functional aryl sulfonates were used to prepare simple aryl or highly acidic fluorinated sulfonated copolymers. The proton conductivity and water sorption of the resulting copolymers increased with the ion exchange capacity, but changing the acidity of the sulfonic acid had no apparent effect.

Protonated sugars: vibrational spectroscopy and conformational structure of protonated O-methyl α-D-galactopyranoside

NASA Astrophysics Data System (ADS)

Rudić, Svemir; Xie, Hong-bin; Gerber, R. Benny; Simons, John P.

2012-08-01

'Bridging' protons provide a common structural motif in biological assemblies such as proton wires and proton-bound dimers. Here we present a 'proof-of-principle' computational and vibrational spectroscopic investigation of an 'intra-molecular proton-bound dimer,' O-methyl α-D-galactopyranoside (αMeGal-H+), generated in the gas phase through photo-ionisation of its complex with phenol in a molecular beam. Its vibrational spectrum corresponds well with a classical molecular dynamics simulation conducted 'on-the-fly' and also with the lowest-energy structures predicted by DFT and ab initio calculations. They reveal proton-bound structures that bridge neighbouring pairs of oxygen atoms, preferentially O6 and O4, linked together within the carbohydrate scaffold. Motivated by the possibility of an entry into the microscopic mechanism of its acid (or enzyme)-catalysed hydrolysis, we also report the corresponding predictions for its singly hydrated complex.

Advanced Materials for PEM-Based Fuel Cell Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

James E. McGrath

2005-10-26

Proton exchange membrane fuel cells (PEMFCs) are quickly becoming attractive alternative energy sources for transportation, stationary power, and small electronics due to the increasing cost and environmental hazards of traditional fossil fuels. Two main classes of PEMFCs include hydrogen/air or hydrogen/oxygen fuel cells and direct methanol fuel cells (DMFCs). The current benchmark membrane for both types of PEMFCs is Nafion, a perfluorinated sulfonated copolymer made by DuPont. Nafion copolymers exhibit good thermal and chemical stability, as well as very high proton conductivity under hydrated conditions at temperatures below 80 °C. However, application of these membranes is limited due to theirmore » high methanol permeability and loss of conductivity at high temperatures and low relative humidities. These deficiencies have led to the search for improved materials for proton exchange membranes. Potential PEMs should have good thermal, hydrolytic, and oxidative stability, high proton conductivity, selective permeability, and mechanical durability over long periods of time. Poly(arylene ether)s, polyimides, polybenzimidazoles, and polyphenylenes are among the most widely investigated candidates for PEMs. Poly(arylene ether)s are a promising class of proton exchange membranes due to their excellent thermal and chemical stability and high glass transition temperatures. High proton conductivity can be achieved through post-sulfonation of poly(arylene ether) materials, but this most often results in very high water sorption or even water solubility. Our research has shown that directly polymerized poly(arylene ether) copolymers show important advantages over traditional post-sulfonated systems and also address the concerns with Nafion membranes. These properties were evaluated and correlated with morphology, structure-property relationships, and states of water in the membranes. Further improvements in properties were achieved through incorporation of inorganic fillers, such as phosphotungstic acid and zirconium hydrogen phosphate. Block copolymers were also studied due to the possibility to achieve a desired combination of homopolymer properties as well as the unique morphologies that are possible with block copolymers. Bezoyl substituted poly(p-phenylene) blocks were combined with poly(arylene ether) blocks to merge the structural rigidity of the poly(p-phenylene) with the ductility and high protonic conductivity of the poly(arylene ether)s. As evidenced by our many refereed publications and preprints, the research that we have conducted over the past several years has made a valuable and significant contribution to the literature and to the state of understanding of proton exchange membranes. Our early efforts at scale-up have suggested that the directly polymerized disulfonated poly(arylene ether sulfone) copolymers are commercially viable alternatives for proton exchange membranes. A new process for bipolar plates was developed and is described. An important single domain PEMFC model was developed and is documented in this final report.« less

Positron annihilation characteristics, water uptake and proton conductivity of composite Nafion membranes.

PubMed

Yin, Chongshan; Wang, Lingtao; Li, Jingjing; Zhou, Yawei; Zhang, Haining; Fang, Pengfei; He, Chunqing

2017-06-21

The free volumes and proton conductivities of Nafion membranes were investigated at different humidities by positron annihilation lifetime spectroscopy (PALS) and using an electrochemical workstation, respectively. The results showed that the variation in o-Ps lifetime τ o-Ps was closely associated with the microstructure evolution and the development of hydrophilic ion clusters in Nafion membranes as a function of water uptake, regardless of metal oxide additives. In particular, with increasing relative humidity, the maximum value of τ o-Ps in the Nafion membranes corresponded to the formation of numerous water channels for proton transportation. Numerous well-connected water channels in Nafion-TiO 2 hybrid membranes could be formed at a much lower relative humidity (∼40% RH) than in the pristine one (∼75% RH), due to the better water retention ability of the Nafion-TiO 2 membranes. Further, a percolation behavior of proton conductivity at high water uptake in Nafion membranes was observed, which showed that the percolation of ionic-water clusters occurred at the water uptake of ∼4.5 wt%, and ∼6 wt% was basically enough for the formation of a well-connected water channel network.

Enhanced proton conductivity of Nafion hybrid membrane under different humidities by incorporating metal-organic frameworks with high phytic acid loading.

PubMed

Li, Zhen; He, Guangwei; Zhang, Bei; Cao, Ying; Wu, Hong; Jiang, Zhongyi; Tiantian, Zhou

2014-06-25

In this study, phytic acid (myo-inositol hexaphosphonic acid) was first immobilized by MIL101 via vacuum-assisted impregnation method. The obtained phytic@MIL101 was then utilized as a novel filler to incorporate into Nafion to fabricate hybrid proton exchange membrane for application in PEMFC under different relative humidities (RHs), especially under low RHs. High loading and uniform dispersion of phytic acid in MIL 101(Cr) were achieved as demonstrated by ICP, FT-IR, XPS, and EDS-mapping. The phytic@MIL101 was dispersed homogeneously in the Nafion matrix when the filler content was less than 12%. Hybrid membranes were evaluated by proton conductivity, mechanical property, thermal stability, and so forth. Remarkably, the Nafion/phytic@MIL hybrid membranes showed high proton conductivity at different RHs, especially under low RHs, which was up to 0.0608 S cm(-1) and 7.63 × 10(-4) S cm(-1) at 57.4% RH and 10.5% RH (2.8 and 11.0 times higher than that of pristine membrane), respectively. Moreover, the mechanical property of Nafion/phtic@MIL hybrid membranes was substantially enhanced and the thermal stability of membranes was well preserved.

Fabrication of low-methanol-permeability sulfonated poly(phenylene oxide) membranes with hollow glass microspheres for direct methanol fuel cells

NASA Astrophysics Data System (ADS)

Ahn, Kisang; Kim, Myeongjin; Kim, Kiho; Ju, Hyun; Oh, Ilgeun; Kim, Jooheon

2015-02-01

Organic/inorganic composite membranes, based on sulfonated poly(phenylene oxide) (SPPO) and hollow glass microspheres (HGMs), with various compositions are prepared for use as proton exchange membranes in direct methanol fuel cells (DMFCs). Reaction time between chlorosulfonic acid solution and PPO is controlled to improve proton conductivity of the SPPO membrane. As a result, SPPO at 38.2% sulfonation is selected as the optimum degree of sulfonation. Afterwards, SPPO is successfully introduced onto the surfaces of HGMs to increase their dispersion in the SPPO matrix. The ion exchange capacities (IEC) and proton conductivities of the membranes decrease with increasing amounts of the SPPO-HGMs, because of the decrease of ionic sites with increasing HGM content. The SPPO-HGM composite membranes exhibit proton conductivities ranging from 0.0350 to 0.0212 S cm-1 and low methanol permeability ranging from 1.02 × 10-6 to 3.41 × 10-7 cm2 s-1 at 20 °C. Furthermore, the SPPO-HGM 9 wt%/SPPO membrane presents a maximum power density of 81.5 mW cm-2 and open circuit voltage of 0.70 V.

A Ta/W mixed addenda heteropolyacid with excellent acid catalytic activity and proton-conducting property

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Shujun; Peng, Qingpo; Chen, Xuenian, E-mail: xnchen@htu.edu.cn

A new HPAs H{sub 20}[P{sub 8}W{sub 60}Ta{sub 12}(H{sub 2}O){sub 4}(OH){sub 8}O{sub 236}]·125H{sub 2}O (H-1) which comprises a Ta/W mixed addenda heteropolyanion, 20 protons, and 125 crystalline water molecules has been prepared through ion-exchange method. The structure and properties of H-1 have been explored in detail. AC impedance measurements indicate that H-1 is a good solid state proton conducting material at room temperature with a conductivity value of 7.2×10{sup −3} S cm{sup −1} (25 °C, 30% RH). Cyclic voltammograms of H-1 indicate the electrocatalytic activity towards the reduction of nitrite. Hammett acidity constant H{sub 0} of H-1 in CH{sub 3}CN ismore » −2.91, which is the strongest among the present known HPAs. Relatively, H-1 exhibits excellent catalytic activities toward acetal reaction. - Highlights: • A Ta/W mixed addenda Heteropolyacid (H-1) was isolated. • Hammett acidity constant H{sub 0} of H-1 is the strongest among the present known HPAs. • H-1 exhibits excellent catalytic activities toward acetal reaction. • H-1 is a good solid state proton conducting material at room temperature.« less

Essential arginine in subunit a and aspartate in subunit c of FoF1 ATP synthase: effect of repositioning within helix 4 of subunit a and helix 2 of subunit c.

PubMed

Langemeyer, Lars; Engelbrecht, Siegfried

2007-07-01

FoF1 ATP synthase couples proton flow through the integral membrane portion Fo (ab2c10) to ATP-synthesis in the extrinsic F1-part ((alphabeta)3gammadeltaepsilon) (Escherichia coli nomenclature and stoichiometry). Coupling occurs by mechanical rotation of subunits c10gammaepsilon relative to (alphabeta)3deltaab2. Two residues were found to be essential for proton flow through ab2c10, namely Arg210 in subunit a (aR210) and Asp61 in subunits c (cD61). Their deletion abolishes proton flow, but "horizontal" repositioning, by anchoring them in adjacent transmembrane helices, restores function. Here, we investigated the effects of "vertical" repositioning aR210, cD61, or both by one helical turn towards the N- or C-termini of their original helices. Other than in the horizontal the vertical displacement changes the positions of the side chains within the depth of the membrane. Mutant aR210A/aN214R appeared to be short-circuited in that it supported proton conduction only through EF1-depleted EFo, but not in EFoEF1, nor ATP-driven proton pumping. Mutant cD61N/cM65D grew on succinate, retained the ability to synthesize ATP and supported passive proton conduction but apparently not ATP hydrolysis-driven proton pumping.

Polymer and Composite Membranes for Proton-Conducting, High-Temperature Fuel Cells: A Critical Review

PubMed Central

Quartarone, Eliana; Angioni, Simone; Mustarelli, Piercarlo

2017-01-01

Polymer fuel cells operating above 100 °C (High Temperature Polymer Electrolyte Membrane Fuel Cells, HT-PEMFCs) have gained large interest for their application to automobiles. The HT-PEMFC devices are typically made of membranes with poly(benzimidazoles), although other polymers, such as sulphonated poly(ether ether ketones) and pyridine-based materials have been reported. In this critical review, we address the state-of-the-art of membrane fabrication and their properties. A large number of papers of uneven quality has appeared in the literature during the last few years, so this review is limited to works that are judged as significant. Emphasis is put on proton transport and the physico-chemical mechanisms of proton conductivity. PMID:28773045

Polymer and Composite Membranes for Proton-Conducting, High-Temperature Fuel Cells: A Critical Review.

PubMed

Quartarone, Eliana; Angioni, Simone; Mustarelli, Piercarlo

2017-06-22

Polymer fuel cells operating above 100 °C (High Temperature Polymer Electrolyte Membrane Fuel Cells, HT-PEMFCs) have gained large interest for their application to automobiles. The HT-PEMFC devices are typically made of membranes with poly(benzimidazoles), although other polymers, such as sulphonated poly(ether ether ketones) and pyridine-based materials have been reported. In this critical review, we address the state-of-the-art of membrane fabrication and their properties. A large number of papers of uneven quality has appeared in the literature during the last few years, so this review is limited to works that are judged as significant. Emphasis is put on proton transport and the physico-chemical mechanisms of proton conductivity.

Materials for use as proton conducting membranes for fuel cells

DOEpatents

Einsla, Brian R [Blacksburg, VA; McGrath, James E [Blacksburg, VA

2009-01-06

A family of polymers having pendent sulfonate moieties connected to polymeric main chain phenyl groups are described. These polymers are prepared by the steps of polymerization (using a monomer with a phenyl with an alkoxy substitution), deportation by converting the alkoxy to a hydroxyl, and functionalization of the polymer with a pendant sulfonate group. As an example, sulfonated poly(arylene ether sulfone) copolymers with pendent sulfonic acid groups are synthesized by the direct copolymerization of methoxy-containing poly(arylene ether sulfone)s, then converting the methoxy groups to the reactive hydroxyl form, and finally functionalizing the hydroxyl form with proton-conducting sites through nucleophilic substitution. The family of polymers may have application in proton exchange membranes and in other applications.

Structural and electrical characterization of tamarind seed polysaccharide (TSP) doped with NH4HCO2

NASA Astrophysics Data System (ADS)

Premalatha, M.; Mathavan, T.; Selvasekarapandian, S.; Selvalakshmi, S.

2018-04-01

In the modern era, development of electrochemical energy devices such as batteries, fuel cells and supercapacitors gain attention due to the deficiency of renewable energy resources. More specifically, proton conducting materials create prime interest in the development of electrochemical devices. In this regards, a novel proton conducting biopolymer electrolyte based on Tamarind Seed Polysaccharide (TSP) was synthesized with different concentration of ammonium formate (NH4HCO2). The amorphous nature of the polymer electrolytes has been identified by XRD technique. The observed ionic conductivity values reveal that the biopolymer containing 1 g TSP: 0.4 g NH4HCO2 has highest ionic conductivity 1.23×10-3 S cm-1.

Designer proton-channel transgenic algae for photobiological hydrogen production

DOEpatents

Lee, James Weifu [Knoxville, TN

2011-04-26

A designer proton-channel transgenic alga for photobiological hydrogen production that is specifically designed for production of molecular hydrogen (H.sub.2) through photosynthetic water splitting. The designer transgenic alga includes proton-conductive channels that are expressed to produce such uncoupler proteins in an amount sufficient to increase the algal H.sub.2 productivity. In one embodiment the designer proton-channel transgene is a nucleic acid construct (300) including a PCR forward primer (302), an externally inducible promoter (304), a transit targeting sequence (306), a designer proton-channel encoding sequence (308), a transcription and translation terminator (310), and a PCR reverse primer (312). In various embodiments, the designer proton-channel transgenic algae are used with a gas-separation system (500) and a gas-products-separation and utilization system (600) for photobiological H.sub.2 production.

Bioinspired Ultrastrong Solid Electrolytes with Fast Proton Conduction along 2D Channels.

PubMed

He, Guangwei; Xu, Mingzhao; Zhao, Jing; Jiang, Shengtao; Wang, Shaofei; Li, Zhen; He, Xueyi; Huang, Tong; Cao, Moyuan; Wu, Hong; Guiver, Michael D; Jiang, Zhongyi

2017-07-01

Solid electrolytes have attracted much attention due to their great prospects in a number of energy- and environment-related applications including fuel cells. Fast ion transport and superior mechanical properties of solid electrolytes are both of critical significance for these devices to operate with high efficiency and long-term stability. To address a common tradeoff relationship between ionic conductivity and mechanical properties, electrolyte membranes with proton-conducting 2D channels and nacre-inspired architecture are reported. An unprecedented combination of high proton conductivity (326 mS cm -1 at 80 °C) and superior mechanical properties (tensile strength of 250 MPa) are achieved due to the integration of exceptionally continuous 2D channels and nacre-inspired brick-and-mortar architecture into one materials system. Moreover, the membrane exhibits higher power density than Nafion 212 membrane, but with a comparative weight of only ≈0.1, indicating potential savings in system weight and cost. Considering the extraordinary properties and independent tunability of ion conduction and mechanical properties, this bioinspired approach may pave the way for the design of next-generation high-performance solid electrolytes with nacre-like architecture. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Selective growth of MoS2 for proton exchange membranes with extremely high selectivity.

PubMed

Feng, Kai; Tang, Beibei; Wu, Peiyi

2013-12-26

Proton conductivity and methanol permeability are the most important transport properties of proton exchange membranes (PEMs). The ratio of proton conductivity to methanol permeability is usually called selectivity. Herein, a novel strategy of in situ growth of MoS2 is employed to prepare MoS2/Nafion composite membranes for highly selective PEM. The strong interactions between the Mo precursor ((NH4)2MoS4) and Nafion's sulfonic groups in a suitable solvent environment (DMF) probably lead to a selective growth of MoS2 flakes mainly around the ionic clusters of the resultant MoS2/Nafion composite membrane. Therefore, it would significantly promote the aggregation and hence lead to a better connectivity of these ionic clusters, which favors the increase in proton conductivity. Meanwhile, the existence of MoS2 in the ionic channels effectively prevents methanol transporting through the PEM, contributing to the dramatic decrease in the methanol permeability. Consequently, the MoS2/Nafion composite membranes exhibit greatly increased selectivity. Under some severe conditions, such as 50 °C with 80 v/v% of methanol concentration, an increase in the membrane selectivity by nearly 2 orders of magnitude compared with that of the recast Nafion membrane could be achieved here, proving our method as a very promising way to prepare high-performance PEMs. All these conclusions are confirmed by various characterizations, such as (FE-) SEM, TEM, AFM, IR, Raman, TGA, XRD, etc.

Mechanical and transport properties of layer-by-layer electrospun composite proton exchange membranes for fuel cell applications.

PubMed

Mannarino, Matthew M; Liu, David S; Hammond, Paula T; Rutledge, Gregory C

2013-08-28

Composite membranes composed of highly conductive and selective layer-by-layer (LbL) films and electrospun fiber mats were fabricated and characterized for mechanical strength and electrochemical selectivity. The LbL component consists of a proton-conducting, methanol-blocking poly(diallyl dimethyl ammonium chloride)/sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) (PDAC/sPPO) thin film. The electrospun fiber component consists of poly(trimethyl hexamethylene terephthalamide) (PA 6(3)T) fibers in a nonwoven mat of 60-90% porosity. The bare mats were annealed to improve their mechanical properties, which improvements are shown to be retained in the composite membranes. Spray LbL assembly was used as a means for the rapid formation of proton-conducting films that fill the void space throughout the porous electrospun matrix and create a fuel-blocking layer. Coated mats as thin as 15 μm were fabricated, and viable composite membranes with methanol permeabilities 20 times lower than Nafion and through-plane proton selectivity five and a half times greater than Nafion are demonstrated. The mechanical properties of the spray coated electrospun mats are shown to be superior to the LbL-only system and possess intrinsically greater dimensional stability and lower mechanical hysteresis than Nafion under hydrated conditions. The composite proton exchange membranes fabricated here were tested in an operational direct methanol fuel cell. The results show the potential for higher open circuit voltages (OCV) and comparable cell resistances when compared to fuel cells based on Nafion.

High-Temperature Proton-Conducting Ceramics Developed

NASA Technical Reports Server (NTRS)

Sayir, Ali; Dynys, Frederick W.; Berger, M. H.

2005-01-01

High-temperature protonic conductors (HTPC) are needed for hydrogen separation, hydrogen sensors, fuel cells, and hydrogen production from fossil fuels. The HTPC materials for hydrogen separation at high temperatures are foreseen to be metal oxides with the perovskite structure A(sup 2+)B(sup 4+)C(sup 2-, sub 3) and with the trivalent cation (M(sup 3+)) substitution at the B(sup 4+)-site to introduce oxygen vacancies. The high affinity for hydrogen ions (H(sup +)) is advantageous for protonic transport, but it increases the reactivity toward water (H2O) and carbon dioxide (CO2), which can lead to premature membrane failure. In addition, there are considerable technological challenges related to the processing of HTPC materials. The high melting point and multi-cation chemistry of HTPC materials creates difficulties in in achieving high-density, single-phase membranes by solid-state sintering. The presence of secondary phases and grain-boundary interfaces are detrimental to the protonic conduction and environmental stability of polycrystalline HTPC materials.

Electrochemical performance and durability of carbon supported Pt catalyst in contact with aqueous and polymeric proton conductors.

PubMed

Andersen, Shuang Ma; Skou, Eivind

2014-10-08

Significant differences in catalyst performance and durability are often observed between the use of a liquid electrolyte (e.g., sulfuric acid), and a solid polymer electrolyte (e.g., Nafion). To understand this phenomenon, we studied the electrochemical behavior of a commercially available carbon supported platinum catalyst in four different electrode structures: catalyst powder (CP), catalyst ionomer electrode (CIE), half membrane electrode assembly (HMEA), and full membrane electrode assembly (FMEA) in both ex situ and in situ experiments under a simulated start/stop cycle. We found that the catalyst performance and stability are very much influenced by the presence of the Nafion ionomers. The proton conducting phase provided by the ionomer and the self-assembled electrode structure render the catalysts a higher utilization and better stability. This is probably due to an enhanced dispersion, an improved proton-catalyst interface, the restriction of catalyst particle aggregation, and the improved stability of the ionomer phase especially after the lamination. Therefore, an innovative electrode HMEA design for ex-situ catalyst characterization is proposed. The electrode structure is identical to the one used in a real fuel cell, where the protons transport takes place solely through solid state proton conducting phase.

A-Site Cation Substitutions in Strained Y-Doped BaZrO 3 Multilayer Films Leading to Fast Proton Transport Pathways

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aruta, Carmela; Han, Chu; Zhou, Si

Proton-conducting perovskite oxides form a class of solid electrolytes for novel electrochemical devices operating at moderate temperatures. Here, we use hard X-ray photoelectron spectroscopy, scanning transmission electron microscopy, and density functional theory calculations to investigate the structure and elucidate the origin of the fast proton transport properties of strained ultrathin films of Y-doped BaZrO 3 grown by pulsed lased deposition on NdGaO 3. Our study shows that our BaZr 0.8Y 0.2O 3 films incorporate a significant amount of Y dopants, and to a lesser extent also Zr ions, substituting for Ba 2+, and that these substitutional defects agglomerate forming columnarmore » regions crossing vertically from the surface to the interface the entire film. In conclusion, our calculations also show that, in regions rich in Y substitutions for both Zr and Ba, the proton transfer process involves nearly zero-energy barriers, indicating that A-site cation substitutions by Y lead to fast transport pathways and hence are responsible for the previously observed enhanced values of the proton conductivity of these perovskite oxide films.« less

The chemical and dynamical influence of the anti-viral drug amantadine on the M2 proton channel transmembrane domain.

PubMed

Hu, Jun; Fu, Riqiang; Cross, Timothy A

2007-07-01

The M(2) proton channel plays a vital role in the life cycle of the influenza A virus. His(37), the key residue in the M(2) transmembrane domain (M(2)-TMD), plays a central role in the proton conductance mechanism. The anti-influenza drug, amantadine, inhibits the channel activity through binding to the pore of the M(2) channel. The nuclear spin relaxation data and polarization inversion spin exchange at the magic angle spectra show that both the polypeptide backbone and His(37) side chain are more constrained in the presence of amantadine. Using (15)N cross polarization magic-angle spinning NMR spectroscopy, the protonation of His(37) of M(2)-TMD in lipid bilayers was monitored in the absence and presence of amantadine as a function of pH. Binding amantadine lowers the His(37) pK(a) values by approximately three orders of magnitude compared with the first pK(a) of histidine in amantadine-free M(2)-TMD. Amantadine's influence on the His(37) chemical properties suggests a novel mechanism by which amantadine may inhibit proton conductance.

Friedel-Crafts Crosslinked Highly Sulfonated Polyether Ether Ketone (SPEEK) Membranes for a Vanadium/Air Redox Flow Battery.

PubMed

Merle, Géraldine; Ioana, Filipoi Carmen; Demco, Dan Eugen; Saakes, Michel; Hosseiny, Seyed Schwan

2013-12-30

Highly conductive and low vanadium permeable crosslinked sulfonated poly(ether ether ketone) (cSPEEK) membranes were prepared by electrophilic aromatic substitution for a Vanadium/Air Redox Flow Battery (Vanadium/Air-RFB) application. Membranes were synthesized from ethanol solution and crosslinked under different temperatures with 1,4-benzenedimethanol and ZnCl2 via the Friedel-Crafts crosslinking route. The crosslinking mechanism under different temperatures indicated two crosslinking pathways: (a) crosslinking on the sulfonic acid groups; and (b) crosslinking on the backbone. It was observed that membranes crosslinked at a temperature of 150 °C lead to low proton conductive membranes, whereas an increase in crosslinking temperature and time would lead to high proton conductive membranes. High temperature crosslinking also resulted in an increase in anisotropy and water diffusion. Furthermore, the membranes were investigated for a Vanadium/Air Redox Flow Battery application. Membranes crosslinked at 200 °C for 30 min with a molar ratio between 2:1 (mol repeat unit:mol benzenedimethanol) showed a proton conductivity of 27.9 mS/cm and a 100 times lower VO2+ crossover compared to Nafion.

Morphology Effect on Proton Dynamics in Nafion® 117 and Sulfonated Polyether Ether Ketone

NASA Astrophysics Data System (ADS)

Leong, Jun Xing; Diño, Wilson Agerico; Ahmad, Azizan; Daud, Wan Ramli Wan; Kasai, Hideaki

2016-09-01

We report results of our experimental and theoretical studies on the dynamics of proton conductivity in Nafion® 117 and self-fabricated sulfonated polyether ether ketone (SPEEK) membranes. Knowing that the presence of water molecules in the diffusion process results in a lower energy barrier, we determined the diffusion barriers and corresponding tunneling probabilities of Nafion® 117 and SPEEK system using a simple theoretical model that excludes the medium (water molecules) in the initial calculations. We then propose an equation that relates the membrane conductivity to the tunneling probability. We recover the effect of the medium by introducing a correction term into the proposed equation, which takes into account the effect of the proton diffusion distance and the hydration level. We have also experimentally verified that the proposed equation correctly explain the difference in conductivity between Nafion® 117 and SPEEK. We found that membranes that are to be operated in low hydration environments (high temperatures) need to be designed with short diffusion distances to enhance and maintain high conductivity.

Nanogranular SiO2 proton gated silicon layer transistor mimicking biological synapses

NASA Astrophysics Data System (ADS)

Liu, M. J.; Huang, G. S.; Feng, P.; Guo, Q. L.; Shao, F.; Tian, Z. A.; Li, G. J.; Wan, Q.; Mei, Y. F.

2016-06-01

Silicon on insulator (SOI)-based transistors gated by nanogranular SiO2 proton conducting electrolytes were fabricated to mimic synapse behaviors. This SOI-based device has both top proton gate and bottom buried oxide gate. Electrical transfer properties of top proton gate show hysteresis curves different from those of bottom gate, and therefore, excitatory post-synaptic current and paired pulse facilitation (PPF) behavior of biological synapses are mimicked. Moreover, we noticed that PPF index can be effectively tuned by the spike interval applied on the top proton gate. Synaptic behaviors and functions, like short-term memory, and its properties are also experimentally demonstrated in our device. Such SOI-based electronic synapses are promising for building neuromorphic systems.

Ion conduction mechanisms and thermal properties of hydrated and anhydrous phosphoric acids studied with 1H, 2H, and 31P NMR.

PubMed

Aihara, Yuichi; Sonai, Atsuo; Hattori, Mineyuki; Hayamizu, Kikuko

2006-12-14

To understand the behaviors of phosphoric acids in fuel cells, the ion conduction mechanisms of phosphoric acids in condensed states without free water and in a monomer state with water were studied by measuring the ionic conductivity (sigma) using AC impedance, thermal properties, and self-diffusion coefficients (D) and spin-lattice relaxation times (T1) with multinuclear NMR. The self-diffusion coefficient of the protons (H+ or H3O+), H2O, and H located around the phosphate were always larger than the diffusion coefficients of the phosphates and the disparity increased with increasing phosphate concentration. The diffusion coefficients of the samples containing D2O paralleled those in the protonated samples. Since the 1H NMR T1 values exhibited a minimum with temperature, it was possible to determine the correlation times and they were found to be of nanosecond order for a distance of nanometer order for a flip. The agreement of the ionic conductivities measured directly and those calculated from the diffusion coefficients indicates that the ion conduction obeys the Nernst-Einstein equation in the condensed phosphoric acids. The proton diffusion plays a dominant role in the ion conduction, especially in the condensed phosphoric acids.

The effects of fasting and cold exposure on metabolic rate and mitochondrial proton leak in liver and skeletal muscle of an amphibian, the cane toad Bufo marinus.

PubMed

Trzcionka, M; Withers, K W; Klingenspor, M; Jastroch, M

2008-06-01

Futile cycling of protons across the mitochondrial inner membrane contributes significantly to standard metabolic rate in a variety of ectothermic and endothermic animals, but adaptations of the mitochondrial bioenergetics to different environmental conditions have rarely been studied in ectotherms. Changes in ambient temperature and nutritional status have a great effect on the physiological demands of ectothermic amphibians and may require the adjustment of mitochondrial efficiency. In order to investigate the effect of temperature and nutritional status on the mitochondrial level, we exposed male cane toads to either 10 degrees C or 30 degrees C and fasted half of the animals in each group. Cold exposure resulted in a fourfold reduction of the resting metabolic rate whereas nutritional status had only minor effects. The mitochondrial adjustments to each condition were observed by comparing the proton leak kinetics of isolated liver and skeletal muscle mitochondria at 25 degrees C. In response to cold exposure, liver mitochondria showed a decrease in proton conductance while skeletal muscle mitochondria were unchanged. Additional food deprivation had minor effects in skeletal muscle, but in liver we uncovered surprising differences in energy saving mechanisms between the acclimation temperatures: in warm-acclimated toads, fasting resulted in a decrease of the proton conductance whereas in cold-acclimated toads, the activity of the respiratory chain was reduced. To investigate the molecular mechanism underlying mitochondrial proton leakage, we determined the adenine-nucleotide transporter (ANT) content, which explained tissue-specific differences in the basal proton leak, but neither the ANT nor uncoupling protein (UCP) gene expression correlated with alterations of the proton leak in response to physiological stimuli.

Visualization of Proton and Electron Transfer Processes of a Biochemical Reaction by μSR

NASA Astrophysics Data System (ADS)

Kiyotani, Tamiko; Kobayashi, Masayoshi; Tanaka, Ichiro; Niimura, Nobuo

For the last several years, we have discussed and conducted experiments toward realization of visualization of electron and proton transfer process in an enzyme reaction using muon. As the first step for exploring the useful application of the μSR for the biological system, which is "μSR in Biology". A first μSR experiment on biochemical reaction was conducted using the complex of a digestive enzyme, a kind of serine-protease and the inhibitor at J-PARC and PSI.

Method of synthesis of proton conducting materials

DOEpatents

Garzon, Fernando Henry; Einsla, Melinda Lou; Mukundan, Rangachary

2010-06-15

A method of producing a proton conducting material, comprising adding a pyrophosphate salt to a solvent to produce a dissolved pyrophosphate salt; adding an inorganic acid salt to a solvent to produce a dissolved inorganic acid salt; adding the dissolved inorganic acid salt to the dissolved pyrophosphate salt to produce a mixture; substantially evaporating the solvent from the mixture to produce a precipitate; and calcining the precipitate at a temperature of from about 400.degree. C. to about 1200.degree. C.

Promotional Effect of Molten Carbonates on Proton Conductivity and Oxygen Reduction Reaction - an Experimental and Computational Study

NASA Astrophysics Data System (ADS)

Xiong, Xiaolei

Recent research of Solid oxide fuel cells (SOFCs) is aimed to lower the operating temperature to an intermediate temperature (IT) range of 500 to 700°C, while maintaining a proper performance. This Ph.D. research project investigates the promotional effects of alkaline carbonate eutectics on the proton conductivity of proton conducting electrolytes and cathodic ORR reactivity in SOFCs by both experimental and computational methods. The ionic conductivity of the MC-BZY composite above 500°C increases with the higher loading of MC. The sample exhibited nearly a factor of two higher conductivity in H2-containing atmosphere than in air. First-principles DFT modeling further investigated proton transfer at the interface of BaZrO 3 and molten carbonate. With the presence of carbonate ion, the energy barrier for proton migration becomes as low as 0.332 eV. The modeling indicates the reduction of energy barrier is resulted from the change of rate-determining step from proton transfer between oxygen atoms to proton rotation around oxygen atom. Infiltration of MC into porous cathode can reduce the polarization of resistance (Rp), i.e., enhance the oxygen reduction reaction (ORR) activity. The EIS analysis shows that MC has a beneficial effect on reducing Rp for different cathodes including Au, La0.8Sr 0.2MnO3-delta(LSM), La0.6Sr0.4Co 0.2Fe0.8O3-delta(LSCF) and La2NiO 4+delta (LNO). Specifically, the study on MC loading effect was carried out on LSCF cathode. It shows that a higher loading makes a greater reduction on Rp and the degree of reduction is the same from 500 to 600°C. As the loading increases to 1.4 wt%, the degree of Rp reduction tends to reach a limit. First-principles DFT modeling was further used to investigate the incorporation of oxygen into MC. The formation of CO 52- in molten carbonate was considered as a chemisorption of gas oxygen on the surface of MC infiltrated cathodes. After the formation of CO52-, it reacts with another CO3 2- to form two CO42-, which is a rate-limiting step on potential energy surface. After dissociation, oxygen atoms migrate in molten carbonate, which is energetically favor by intermolecular pathways. An O-O-O linkage is formed between carbonate ions, which facilitates the oxygen migration between carbonate ions.

Enhanced proton conductivity of Nafion composite membrane by incorporating phosphoric acid-loaded covalent organic framework

NASA Astrophysics Data System (ADS)

Yin, Yongheng; Li, Zhen; Yang, Xin; Cao, Li; Wang, Chongbin; Zhang, Bei; Wu, Hong; Jiang, Zhongyi

2016-11-01

Design and fabrication of efficient proton transport channels within solid electrolytes is crucial and challenging to new energy-relevant devices such as proton exchange membrane fuel cells (PEMFCs). In this study, the phosphoric acid (H3PO4) molecules are impregnated into SNW-1-type covalent organic frameworks (COFs) via vacuum assisted method. High loading of H3PO4 in SNW-1 and low guest leaching rate are achieved due to the similar diameter between H3PO4 and micropores in SNW-1. Then the COF-based composite membranes are fabricated for the first time with impregnated COFs (H3PO4@SNW-1) and Nafion matrix. For the composite membranes, the acid-base pairs formed between H3PO4@SNW-1 networks and Nafion optimize the interfacial interactions and hydrophilic domains. The acidic -PO3H2 groups in pores of H3PO4@SNW-1 provide abundant proton transfer sites. As a result, the continuous proton transfer channels with low energy barrier are created. At the filler content of 15 wt%, the composite membrane exhibits a superior proton conductivity of 0.0604 S cm-1 at 51% relative humidity and 80 °C. At the same time, the maximum power density of single fuel cell is 60.3% higher than that of the recast Nafion membrane.

Cosmic ray positron research and silicon track detector development

NASA Technical Reports Server (NTRS)

Jones, W. Vernon; Wefel, John P.

1991-01-01

The purpose was to conduct research on: (1) position sensing detector systems, particularly those based upon silicon detectors, for use in future balloon and satellite experiments; and (2) positrons, electrons, proton, anti-protons, and helium particles as measured by the NASA NMSU Balloon Magnet Facility.

Testing the Tester: Lessons Learned During the Testing of a State-of-the-Art Commercial 14nm Processor Under Proton Irradiation

NASA Technical Reports Server (NTRS)

Szabo, Carl M., Jr.; Duncan, Adam R.; Label, Kenneth A.

2017-01-01

Testing of an Intel 14nm desktop processor was conducted under proton irradiation. We share lessons learned, demonstrating that complex devices beget further complex challenges requiring practical and theoretical investigative expertise to solve.

Water-Free Proton-Conducting Membranes for Fuel Cells

NASA Technical Reports Server (NTRS)

Narayanan, Sekharipuram; Yen, Shiao-Pin

2007-01-01

Poly-4-vinylpyridinebisulfate (P4VPBS) is a polymeric salt that has shown promise as a water-free proton-conducting material (solid electrolyte) suitable for use in membrane/electrode assemblies in fuel cells. Heretofore, proton-conducting membranes in fuel cells have been made from perfluorinated ionomers that cannot conduct protons in the absence of water and, consequently, cannot function at temperatures >100 C. In addition, the stability of perfluorinated ionomers at temperatures >100 C is questionable. However, the performances of fuel cells of the power systems of which they are parts could be improved if operating temperatures could be raised above 140 C. What is needed to make this possible is a solid-electrolyte material, such as P4VPBS, that can be cast into membranes and that both retains proton conductivity and remains stable in the desired higher operating temperature range. A family of solid-electrolyte materials different from P4VPBS was described in Anhydrous Proton-Conducting Membranes for Fuel Cells (NPO-30493), NASA Tech Briefs, Vol. 29, No. 8 (August 2005), page 48. Those materials notably include polymeric quaternized amine salts. If molecules of such a polymeric salt could be endowed with flexible chain structures, it would be possible to overcome the deficiencies of simple organic amine salts that must melt before being able to conduct protons. However, no polymeric quaternized amine salts have yet shown to be useful in this respect. The present solid electrolyte is made by quaternizing the linear polymer poly- 4-vinylpyridine (P4VP) to obtain P4VPBS. It is important to start with P4VP having a molecular weight of 160,000 daltons because P4VPBS made from lower-molecular-weight P4VP yields brittle membranes. In an experimental synthesis, P4VP was dissolved in methanol and then reacted with an excess of sulfuric acid to precipitate P4VPBS. The precipitate was recovered, washed several times with methanol to remove traces of acid, and dried to a white granular solid. In another synthesis, nanoparticles of silica rich with surface hydroxyl groups were added to P4VP in methanol solution, which was then reacted with excess sulfuric acid to precipitate granules of a composite that most probably had the composition (P4VPBS)-SiO2-SiO(HSO4)2. The granular P4VPBS produced in the first-mentioned synthesis was dissolved in water to make a glue-like, turbid solution; the granular P4VPBS/silica composite produced in the second-mentioned synthesis was mixed with water to make a turbid, glue-like suspension. The proportions of polymer salt to water in such preparations can be varied; it was found that approximately equal parts of water and polymer salt yield a solution or suspension amenable to further processing.

Giant photoeffect in proton transport through graphene membranes

NASA Astrophysics Data System (ADS)

Lozada-Hidalgo, Marcelo; Zhang, Sheng; Hu, Sheng; Kravets, Vasyl G.; Rodriguez, Francisco J.; Berdyugin, Alexey; Grigorenko, Alexander; Geim, Andre K.

2018-04-01

Graphene has recently been shown to be permeable to thermal protons1, the nuclei of hydrogen atoms, which sparked interest in its use as a proton-conducting membrane in relevant technologies1-4. However, the influence of light on proton permeation remains unknown. Here we report that proton transport through Pt-nanoparticle-decorated graphene can be enhanced strongly by illuminating it with visible light. Using electrical measurements and mass spectrometry, we find a photoresponsivity of ˜104 A W-1, which translates into a gain of ˜104 protons per photon with response times in the microsecond range. These characteristics are competitive with those of state-of-the-art photodetectors that are based on electron transport using silicon and novel two-dimensional materials5-7. The photo-proton effect could be important for graphene's envisaged use in fuel cells and hydrogen isotope separation. Our observations may also be of interest for other applications such as light-induced water splitting, photocatalysis and novel photodetectors.

Sulfonated graphene oxide/nafion composite membrane for vanadium redox flow battery.

PubMed

Kim, Byung Guk; Han, Tae Hee; Cho, Chang Gi

2014-12-01

Nafion is the most frequently used as the membrane material due to its good proton conductivity, and excellent chemical and mechanical stabilities. But it is known to have poor barrier property due to its well-developed water channels. In order to overcome this drawback, graphene oxide (GO) derivatives were introduced for Nafion composite membranes. Sulfonated graphene oxide (sGO) was prepared from GO. Both sGO and GO were treated each with phenyl isocyanate and transformed into corresponding isGO and iGO in order to promote miscibility with Nafion. Then composite membranes were obtained, and the adaptability as a membrane for vanadium redox flow battery (VRFB) was investigated in terms of proton conductivity and vanadium permeability. Compared to a pristine Nafion, proton conductivities of both isGO/Nafion and iGO/Nafion membranes showed less temperature sensitivity. Both membranes also showed quite lower vanadium permeability at room temperature. Selectivity of the membrane was the highest for isGO/Nafion and the lowest for the pristine Nafion.

Changes in CR-39 proton sensitivity due to prolonged exposure to high vacuums relevant to the National Ignition Facility and OMEGA.

PubMed

Manuel, M J-E; Rosenberg, M J; Sinenian, N; Rinderknecht, H; Zylstra, A B; Séguin, F H; Frenje, J; Li, C K; Petrasso, R D

2011-09-01

When used at facilities like OMEGA and the NIF, CR-39 is exposed to high vacuum environments before and after irradiation by charged particles and neutrons. Using an electrostatic linear accelerator at MIT, studies have been conducted to investigate the effects of high vacuum exposure on the sensitivity of CR-39 to fusion protons in the ~1-9 MeV energy range. High vacuum conditions, of order 10(-5) Torr, experienced by CR-39 samples at these facilities were emulated. It is shown that vacuum exposure times longer than ~16 h before proton irradiation result in a decrease in proton sensitivity, whereas no effect was observed for up to 67 h of vacuum exposure after proton irradiation. CR-39 sensitivity curves are presented for samples with prolonged exposure to high vacuum before and after proton irradiation. © 2011 American Institute of Physics

Thermally triggered polyrotaxane translational motion helps proton transfer.

PubMed

Ge, Xiaolin; He, Yubin; Liang, Xian; Wu, Liang; Zhu, Yuan; Yang, Zhengjin; Hu, Min; Xu, Tongwen

2018-06-12

Synthetic polyelectrolytes, capable of fast transporting protons, represent a challenging target for membrane engineering in so many fields, for example, fuel cells, redox flow batteries, etc. Inspired by the fast advance in molecular machines, here we report a rotaxane based polymer entity assembled via host-guest interaction and prove that by exploiting the thermally triggered translational motion (although not in a controlled manner) of mechanically bonded rotaxane, exceptionally fast proton transfer can be fulfilled at an external thermal input. The relative motion of the sulfonated axle to the ring in rotaxane happens at ~60 °C in our cases and because of that a proton conductivity (indicating proton transfer rate) of 260.2 mS cm -1 , which is much higher than that in the state-of-the-art Nafion, is obtained at a relatively low ion-exchange capacity (representing the amount of proton transfer groups) of 0.73 mmol g -1 .

The voltage-gated proton channel: a riddle, wrapped in a mystery, inside an enigma

PubMed Central

DeCoursey, Thomas E.

2016-01-01

The main properties of voltage gated proton channels are described, along with what is known about how the channel protein structure accomplishes these functions. Just as protons are unique among ions, proton channels are unique among ion channels. Their four transmembrane helices sense voltage, the pH gradient, and conduct protons exclusively. Selectivity is achieved by the unique ability of H3O+ to protonate an Asp-Arg salt bridge. Pathognomonic sensitivity of gating to the pH gradient ensures channel opening only when acid extrusion will result, which is crucial to most biological functions. An exception occurs in dinoflagellates in which H+ influx through HV1 triggers the bioluminescent flash. Pharmacological interventions that promise to ameliorate cancer, asthma, brain damage in ischemic stroke, Alzheimer’s disease, autoimmune diseases, and numerous other conditions, await future progress. PMID:25964989

Large transient nonproton ion movements in purple membrane suspensions are abolished by solubilization in Triton X-100.

PubMed Central

Marinetti, T; Mauzerall, D

1986-01-01

Light-induced release/uptake of both protons and other ions cause transient changes in conductivity in suspensions of purple membrane (PM) fragments (Marinetti, Tim, and David Mauzerall, 1983, Proc. Natl. Acad. Sci. USA, 80:178-180). We find that the release/uptake of nonproton ions with quantum yield greater than 1 is observed at most pHs and ionic strengths. Only at both low pH and low ionic strength is the conductivity transient mostly due to protons. Our hypothesis is that during the photocycle, changes occur in the PM's dense surface charge distribution that result in changes in the number of counterions bound or condensed at the membrane surface. To test this, the PM structure was perturbed with the nonionic detergent Triton X-100. Immediately after addition, Triton does not abolish the nonproton ion movements; in fact at low detergent concentrations (0.02% vol/vol) the signal amplitudes increased considerably. However, when PM is completely solubilized into monomers in Triton, the conductivity transients are due to protons alone, though at lower quantum yield compared with native PM. These results suggest that changes in the surface charge distribution in native PM's photocycle could contribute to proton transfer between the aqueous phase and bR itself. PMID:3019444

Investigation of La1−xSrxCrO3−∂ (x ~ 0.1) as Membrane for Hydrogen Production

PubMed Central

Larring, Yngve; Vigen, Camilla; Ahouanto, Florian; Fontaine, Marie-Laure; Peters, Thijs; Smith, Jens B.; Norby, Truls; Bredesen, Rune

2012-01-01

Various inorganic membranes have demonstrated good capability to separate hydrogen from other gases at elevated temperatures. Hydrogen-permeable, dense, mixed proton-electron conducting ceramic oxides offer superior selectivity and thermal stability, but chemically robust candidates with higher ambipolar protonic and electronic conductivity are needed. In this work, we present for the first time the results of various investigations of La1−xSrxCrO3−∂ membranes for hydrogen production. We aim in particular to elucidate the material’s complex transport properties, involving co-ionic transport of oxide ions and protons, in addition to electron holes. This opens some new possibilities for efficient heat and mass transfer management in the production of hydrogen. Conductivity measurements as a function of pH2 at constant pO2 exhibit changes that reveal a significant hydration and presence of protons. The flux and production of hydrogen have been measured under different chemical gradients. In particular, the effect of water vapor in the feed and permeate gas stream sides was investigated with the aim of quantifying the ratio of hydrogen production by hydrogen flux from feed to permeate and oxygen flux the opposite way (“water splitting”). Deuterium labeling was used to unambiguously prove flux of hydrogen species. PMID:24958299

Test report: Electron-proton spectrometer qualification test unit, qualification test

NASA Technical Reports Server (NTRS)

Vincent, D. L.

1972-01-01

Qualification tests of the electron-proton spectrometer test unit are presented. The tests conducted were: (1) functional, (2) thermal/vacuum, (3) electromagnetic interference, (4) acoustic, (5) shock, (6) vibration, and (7) humidity. Results of each type of test are presented in the form of data sheets.

AC impedance investigations of proton conduction in Nafion(sup TM)

NASA Astrophysics Data System (ADS)

Cahan, B. D.; Wainright, J. S.

1993-12-01

AC impedance spectroscopy has been employed to study the conduction of protons in Nafion 117 polymer electrolyte membrane. Both two- and four-electrode geometries have been used to uniquely distinguish between the membrane impedance and the interfacial impedances. The results show that the impedance of Nafion for frequencies up to 100 kHz is characterized by a pure resistance, similar to conventional liquid electrolytes. The frequency dependent features observed using a two-electrode geometry are shown to be consistent will well-characterized interfacial impedances and do not arise from ionic conduction in the membrane. These results show that previous two-electrode studies reported in the literature have misinterpreted the impedance of the electrode interfaces as belonging to the conduction process in the electrolyte.

Novel proton conducting polymer electrolytes based on polyparabanic acid doped with H 3PO 4 for high temperature fuel cell

NASA Astrophysics Data System (ADS)

Aihara, Yuichi; Sonai, Atsuo

Three novel proton conducting polymer electrolytes based on polyparabanic acid doped with H 3PO 4 were synthesized and their use in high temperature fuel cells characterized. The precursor polymers, PMD-Im, POD-Im and PDMDP-Im, were synthesized by cyclization polymerization of diisocynanates. After doping with H 3PO 4, the ionic conductivity and the thermal degradation were studied by using the AC impedance method and thermal gravimetric analysis, respectively. These membranes showed high ionic conductivity of the order of 10 -2 S cm -1 at 423 K with good thermal stability. Their application to fuel cells was demonstrated and polarization curves were obtained at 423 K were obtained without humidification.

Origins of Protons in C-H Bond Insertion Products of Phenols: Proton-Self-Sufficient Function via Water Molecules.

PubMed

Luo, Zhoujie; Gao, Ya; Zhu, Tong; Zhang, John Zenghui; Xia, Fei

2017-08-31

Water molecules can serve as proton shuttles for proton transfer in the C-H bond insertion reactions catalyzed by transition metal complexes. Recently, the control experiments performed for C-H bond insertion of phenol and anisol by gold carbenes show that large discrepancy exists in the yields of hydrogenated and deuterated products. Thus, we conducted a detailed theoretical analysis on the function of water molecules in the C-H bond insertion reactions. The comparison of calculated results and control experiments indicates that the solution water molecules play a crucial role of proton shuttle in C-H bond insertion. In particular, it was found that the hydroxyl groups in phenols were capable of donating protons via water shuttles for the production of C-H products, which had a substantial influence on the yields of inserted products. The hydroxyl groups instead of C-H bonds in phenols function like "proton reservoirs" in the C-H bond insertion, which we call the "proton self-sufficient" (PSS) function of phenol. The PSS function of phenol indicates that the substrates with and without proton reservoirs will lead to different C-H bond insertion products.

Selectivity Mechanism of the Voltage-gated Proton Channel, HV1

NASA Astrophysics Data System (ADS)

Dudev, Todor; Musset, Boris; Morgan, Deri; Cherny, Vladimir V.; Smith, Susan M. E.; Mazmanian, Karine; Decoursey, Thomas E.; Lim, Carmay

2015-05-01

Voltage-gated proton channels, HV1, trigger bioluminescence in dinoflagellates, enable calcification in coccolithophores, and play multifarious roles in human health. Because the proton concentration is minuscule, exquisite selectivity for protons over other ions is critical to HV1 function. The selectivity of the open HV1 channel requires an aspartate near an arginine in the selectivity filter (SF), a narrow region that dictates proton selectivity, but the mechanism of proton selectivity is unknown. Here we use a reduced quantum model to elucidate how the Asp-Arg SF selects protons but excludes other ions. Attached to a ring scaffold, the Asp and Arg side chains formed bidentate hydrogen bonds that occlude the pore. Introducing H3O+ protonated the SF, breaking the Asp-Arg linkage and opening the conduction pathway, whereas Na+ or Cl- was trapped by the SF residue of opposite charge, leaving the linkage intact, thus preventing permeation. An Asp-Lys SF behaved like the Asp-Arg one and was experimentally verified to be proton-selective, as predicted. Hence, interacting acidic and basic residues form favorable AspH0-H2O0-Arg+ interactions with hydronium but unfavorable Asp--X-/X+-Arg+ interactions with anions/cations. This proposed mechanism may apply to other proton-selective molecules engaged in bioenergetics, homeostasis, and signaling.

Anomalous enhancement of proton conductivity for water molecular clusters stabilized in interstitial spaces of porous molecular crystals.

PubMed

Tadokoro, Makoto; Ohhata, Yuki; Shimazaki, Yuriko; Ishimaru, Shin'ichi; Yamada, Teppei; Nagao, Yuki; Sugaya, Tomoaki; Isoda, Kyosuke; Suzuki, Yuta; Kitagawa, Hiroshi; Matsui, Hiroshi

2014-10-13

In an investigation into the proton conductivity of crystallized water clusters confined within low-dimensional nanoporous materials, we have found that water-stable nanoporous crystals are formed by complementary hydrogen bonding between [Co(III) (H2 bim)3 ](3+) (H2 bim: 2,2'-biimidazole) and TATC(3-) (1,3,5- tricarboxyl-2,4,6-triazinate); the O atoms in the -COO(-) groups of TATC(3-) in the porous outer wall are strongly hydrogen bonded with H2 O, forming two types of WMCs (water molecular clusters): a spirocyclic tetramer chain (SCTC) that forms infinite open 1D channels, and an isolated cyclic tetramer (ICT) present in the void space. The ICT is constructed from four H2 O molecules as a novel C2 -type WMC, which are hydrogen bonded with four-, three-, and two-coordination spheres, respectively. The largest structural fluctuation is observed at elevated temperatures from the two-coordinated H2 O molecules, which begin to rapidly and isotropically fluctuate on heating. This behavior can be rationalized by a simple model for the elucidation of pre-melting phenomena, similar to those in ice surfaces as the temperature increases. Moreover, high proton conductivity of SCTCs (ca. 10(-5) S cm(-1) at 300 K with an activation energy of 0.30 eV) through a proton-hole mechanism was observed for pellet samples using the alternating impedance method. The proton conductivity exhibits a slight enhancement of about 0.1×10(-5) S cm(-1) at 274 K due to a structural transition upon approaching this temperature that elongates the unit cell along the b-axis. The proton-transfer route can be predicted in WMCs, as O(4) of an H2 O molecule at the center of an SCTC shows a motion that rotates the dipole in the b-axis direction, but not the c-axis; the thermal ellipsoids of O(4) based on anisotropic temperature factors obtained by X-ray crystallography reflect a structural fluctuation along the b-axis direction induced by [Co(III) (H2 bim)3 ](3+) . © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Analysis of sources of bulk conductivity change in saturated silica sand after unbuffered TCE oxidation by permanganate.

PubMed

Hort, Ryan D; Revil, André; Munakata-Marr, Junko

2014-09-01

Time lapse resistivity surveys could potentially improve monitoring of permanganate-based in situ chemical oxidation (ISCO) of organic contaminants such as trichloroethene (TCE) by tracking changes in subsurface conductivity that result from injection of permanganate and oxidation of the contaminant. Bulk conductivity and pore fluid conductivity changes during unbuffered TCE oxidation using permanganate are examined through laboratory measurements and conductivity modeling using PHREEQC in fluid samples and porous media samples containing silica sand. In fluid samples, oxidation of one TCE molecule produces three chloride ions and one proton, resulting in an increase in fluid electrical conductivity despite the loss of two permanganate ions in the reaction. However, in saturated sand samples in which up to 8mM TCE was oxidized, at least 94% of the fluid conductivity associated with the presence of protons was removed within 3h of sand contact, most likely through protonation of silanol groups found on the surface of the sand grains. Minor conductivity effects most likely associated with pH-dependent reductive dissolution of manganese dioxide were also observed but not accounted for in pore-fluid conductivity modeling. Unaccounted conductivity effects resulted in an under-calculation of post-reaction pore fluid conductivity of 2.1% to 5.5%. Although small increases in the porous media formation factor resulting from precipitation of manganese dioxide were detected (about 3%), these increases could not be confirmed to be statistically significant. Both injection of permanganate and oxidation of TCE cause increases in bulk conductivity that would be detectable through time-lapse resistivity surveys in field conditions. Copyright © 2014 Elsevier B.V. All rights reserved.

Composite proton exchange membrane based on sulfonated organic nanoparticles

NASA Astrophysics Data System (ADS)

Pitia, Emmanuel Sokiri

As the world sets its sight into the future, energy remains a great challenge. Proton exchange membrane (PEM) fuel cell is part of the solution to the energy challenge because of its high efficiency and diverse application. The purpose of the PEM is to provide a path for proton transport and to prevent direct mixing of hydrogen and oxygen at the anode and the cathode, respectively. Hence, PEMs must have good proton conductivity, excellent chemical stability, and mechanical durability. The current state-of-the-art PEM is a perfluorosulfonate ionomer, Nafion®. Although Nafion® has many desirable properties, it has high methanol crossover and it is expensive. The objective of this research was to develop a cost effective two-phase, composite PEM wherein a dispersed conductive organic phase preferentially aligned in the transport direction controls proton transport, and a continuous hydrophobic phase provides mechanical durability to the PEM. The hypothesis that was driving this research was that one might expect better dispersion, higher surface to volume ratio and improved proton conductivity of a composite membrane if the dispersed particles were nanometer in size and had high ion exchange capacity (IEC, = [mmol sulfonic acid]/gram of polymer). In view of this, considerable efforts were employed in the synthesis of high IEC organic nanoparticles and fabrication of a composite membrane with controlled microstructure. High IEC, ~ 4.5 meq/g (in acid form, theoretical limit is 5.4 meq/g) nanoparticles were achieved by emulsion copolymerization of a quaternary alkyl ammonium (QAA) neutralized-sulfonated styrene (QAA-SS), styrene, and divinylbenzene (DVB). The effects of varying the counterion of the sulfonated styrene (SS) monomer (alkali metal and QAA cations), SS concentration, and the addition of a crosslinking agent (DVB) on the ability to stabilize the nanoparticles to higher IECs were assessed. The nanoparticles were ion exchanged to acid form. The extent of ion exchange was characterized with solid state 13C NMR spectroscopy, FTIR spectroscopy, TGA, elemental analysis, and titration. The results indicate the extent of ion exchange was ~ 70-80%. Due to the mass of QAA, the remaining QAA reduced the IEC of the nanoparticles to < 2.2 meq/g. In fabricating the composite membranes, the nanoparticles and polystyrene were solution cast in a continuous process with and without electric field. The electric field had no effect on the water uptake. Based on the morphology and the proton conductivity, it appears orientation of the nanoparticles did not occur. We hypothesize the lack of orientation was caused by swelling of the particles with the solvent. The solvent inside the particle minimized polarizability, and thus prevented orientation. The composite membranes were limited to low proton conductivity of ~ 10-5 S/cm due to low IEC of the nanoparticles, but good dispersion of the nanoparticles was achieved. Future work should look into eliminating the QAA during synthesis and developing a rigid core for the nanoparticles.

Visualization of the Diffusion Pathway of Protons in (NH4)2Si0.5Ti0.5P4O13 as an Electrolyte for Intermediate-Temperature Fuel Cells.

PubMed

Sun, Chunwen; Chen, Lanli; Shi, Siqi; Reeb, Berthold; López, Carlos Alberto; Alonso, José Antonio; Stimming, Ulrich

2018-01-16

We demonstrate that (NH 4 ) 2 Si 0.5 Ti 0.5 P 4 O 13 is an excellent proton conductor. The crystallographic information concerning the hydrogen positions is unraveled from neutron-powder-diffraction (NPD) data for the first time. This study shows that all the hydrogen atoms are connected though H bonds, establishing a two-dimensional path between the [(Si 0.5 Ti 0.5 )P 4 O 13 2- ] n layers for proton diffusion across the crystal structure by breaking and reconstructing intermediate H-O═P bonds. This transient species probably reduces the potential energy of the H jump from an ammonium unit to the next neighboring NH 4 + unit. Both theoretical and experimental results support an interstitial-proton-conduction mechanism. The proton conductivities of (NH 4 ) 2 Si 0.5 Ti 0.5 P 4 O 13 reach 0.0061 and 0.024 S cm -1 in humid air at 125 and 250 °C, respectively. This finding demonstrates that (NH 4 ) 2 Si 0.5 Ti 0.5 P 4 O 13 is a promising electrolyte material operating at 150-250 °C. This work opens up a new avenue for designing and fabricating high-performance inorganic electrolytes.

Quantum dynamics in continuum for proton transport II: Variational solvent-solute interface.

PubMed

Chen, Duan; Chen, Zhan; Wei, Guo-Wei

2012-01-01

Proton transport plays an important role in biological energy transduction and sensory systems. Therefore, it has attracted much attention in biological science and biomedical engineering in the past few decades. The present work proposes a multiscale/multiphysics model for the understanding of the molecular mechanism of proton transport in transmembrane proteins involving continuum, atomic, and quantum descriptions, assisted with the evolution, formation, and visualization of membrane channel surfaces. We describe proton dynamics quantum mechanically via a new density functional theory based on the Boltzmann statistics, while implicitly model numerous solvent molecules as a dielectric continuum to reduce the number of degrees of freedom. The density of all other ions in the solvent is assumed to obey the Boltzmann distribution in a dynamic manner. The impact of protein molecular structure and its charge polarization on the proton transport is considered explicitly at the atomic scale. A variational solute-solvent interface is designed to separate the explicit molecule and implicit solvent regions. We formulate a total free-energy functional to put proton kinetic and potential energies, the free energy of all other ions, and the polar and nonpolar energies of the whole system on an equal footing. The variational principle is employed to derive coupled governing equations for the proton transport system. Generalized Laplace-Beltrami equation, generalized Poisson-Boltzmann equation, and generalized Kohn-Sham equation are obtained from the present variational framework. The variational solvent-solute interface is generated and visualized to facilitate the multiscale discrete/continuum/quantum descriptions. Theoretical formulations for the proton density and conductance are constructed based on fundamental laws of physics. A number of mathematical algorithms, including the Dirichlet-to-Neumann mapping, matched interface and boundary method, Gummel iteration, and Krylov space techniques are utilized to implement the proposed model in a computationally efficient manner. The gramicidin A channel is used to validate the performance of the proposed proton transport model and demonstrate the efficiency of the proposed mathematical algorithms. The proton channel conductances are studied over a number of applied voltages and reference concentrations. A comparison with experimental data verifies the present model predictions and confirms the proposed model. Copyright © 2011 John Wiley & Sons, Ltd.

Hydrogen molecule defect in proton-conductive SrTiO3 Perovskite

NASA Astrophysics Data System (ADS)

Onishi, Taku

2017-11-01

In proton-conductive SrTiO3 perovskite, no hydrogen molecule defect ideally exists. However, the unforeseen chemical reaction is often observed after the use of fuel cell. From the viewpoint of battery safety, we have investigated the effect of hydrogen molecule defect by molecular orbital analysis. When counter cation vacancy exists, the activation energy for hydrogen molecule migration was 1.39 - 1.50 eV, which is much smaller than the dissociation energy of hydrogen molecule. It implies that hydrogen molecule may migrate without its dissociation.

Polarity governed selective amplification of through plane proton shuttling in proton exchange membrane fuel cells.

PubMed

Gautam, Manu; Chattanahalli Devendrachari, Mruthyunjayachari; Thimmappa, Ravikumar; Raja Kottaichamy, Alagar; Pottachola Shafi, Shahid; Gaikwad, Pramod; Makri Nimbegondi Kotresh, Harish; Ottakam Thotiyl, Musthafa

2017-03-15

Graphene oxide (GO) anisotropically conducts protons with directional dominance of in plane ionic transport (σ IP) over the through plane (σ TP). In a typical H 2 -O 2 fuel cell, since the proton conduction occurs through the plane during its generation at the fuel electrode, it is indeed inevitable to selectively accelerate GO's σ TP for advancement towards a potential fuel cell membrane. We successfully achieved ∼7 times selective amplification of GO's σ TP by tuning the polarity of the dopant molecule in its nanoporous matrix. The coexistence of strongly non-polar and polar domains in the dopant demonstrated a synergistic effect towards σ TP with the former decreasing the number of water molecules coordinated to protons by ∼3 times, diminishing the effects of electroosmotic drag exerted on ionic movements, and the latter selectively accelerating σ TP across the catalytic layers by bridging the individual GO planes via extensive host guest H-bonding interactions. When they are decoupled, the dopant with mainly non-polar or polar features only marginally enhances the σ TP, revealing that polarity factors contribute to fuel cell relevant transport properties of GO membranes only when they coexist. Fuel cell polarization and kinetic analyses revealed that these multitask dopants increased the fuel cell performance metrics of the power and current densities by ∼3 times compared to the pure GO membranes, suggesting that the functional group factors of the dopants are of utmost importance in GO-based proton exchange membrane fuel cells.

Surface Chemistry of La0.99Sr0.01NbO4-d and Its Implication for Proton Conduction.

PubMed

Li, Cheng; Pramana, Stevin S; Ni, Na; Kilner, John; Skinner, Stephen J

2017-09-06

Acceptor-doped LaNbO 4 is a promising electrolyte material for proton-conducting fuel cell (PCFC) applications. As charge transfer processes govern device performance, the outermost surface of acceptor-doped LaNbO 4 will play an important role in determining the overall cell performance. However, the surface composition is poorly characterized, and the understanding of its impact on the proton exchange process is rudimentary. In this work, the surface chemistry of 1 atom % Sr-doped LaNbO 4 (La 0.99 Sr 0.01 NbO 4-d , denoted as LSNO) proton conductor is characterized using LEIS and SIMS. The implication of a surface layer on proton transport is studied using the isotopic exchange technique. It has shown that a Sr-enriched but La-deficient surface layer of about 6-7 nm thick forms after annealing the sample under static air at 1000 °C for 10 h. The onset of segregation is found to be between 600 and 800 °C, and an equilibrium surface layer forms after 10 h annealing. A phase separation mechanism, due to the low solubility of Sr in LaNbO 4 , has been proposed to explain the observed segregation behavior. The surface layer was concluded to impede the water incorporation process, leading to a reduced isotopic fraction after the D 2 16 O wet exchange process, highlighting the impact of surface chemistry on the proton exchange process.

Friedel–Crafts Crosslinked Highly Sulfonated Polyether Ether Ketone (SPEEK) Membranes for a Vanadium/Air Redox Flow Battery

PubMed Central

Merle, Géraldine; Ioana, Filipoi Carmen; Demco, Dan Eugen; Saakes, Michel; Hosseiny, Seyed Schwan

2014-01-01

Highly conductive and low vanadium permeable crosslinked sulfonated poly(ether ether ketone) (cSPEEK) membranes were prepared by electrophilic aromatic substitution for a Vanadium/Air Redox Flow Battery (Vanadium/Air-RFB) application. Membranes were synthesized from ethanol solution and crosslinked under different temperatures with 1,4-benzenedimethanol and ZnCl2 via the Friedel–Crafts crosslinking route. The crosslinking mechanism under different temperatures indicated two crosslinking pathways: (a) crosslinking on the sulfonic acid groups; and (b) crosslinking on the backbone. It was observed that membranes crosslinked at a temperature of 150 °C lead to low proton conductive membranes, whereas an increase in crosslinking temperature and time would lead to high proton conductive membranes. High temperature crosslinking also resulted in an increase in anisotropy and water diffusion. Furthermore, the membranes were investigated for a Vanadium/Air Redox Flow Battery application. Membranes crosslinked at 200 °C for 30 min with a molar ratio between 2:1 (mol repeat unit:mol benzenedimethanol) showed a proton conductivity of 27.9 mS/cm and a 100 times lower VO2+ crossover compared to Nafion. PMID:24957118

Molecular mechanism of H+ conduction in the single-file water chain of the gramicidin channel.

PubMed

Pomès, Régis; Roux, Benoît

2002-05-01

The conduction of protons in the hydrogen-bonded chain of water molecules (or "proton wire") embedded in the lumen of gramicidin A is studied with molecular dynamics free energy simulations. The process may be described as a "hop-and-turn" or Grotthuss mechanism involving the chemical exchange (hop) of hydrogen nuclei between hydrogen-bonded water molecules arranged in single file in the lumen of the pore, and the subsequent reorganization (turn) of the hydrogen-bonded network. Accordingly, the conduction cycle is modeled by two complementary steps corresponding respectively to the translocation 1) of an ionic defect (H+) and 2) of a bonding defect along the hydrogen-bonded chain of water molecules in the pore interior. The molecular mechanism and the potential of mean force are analyzed for each of these two translocation steps. It is found that the mobility of protons in gramicidin A is essentially determined by the fine structure and the dynamic fluctuations of the hydrogen-bonded network. The translocation of H+ is mediated by spontaneous (thermal) fluctuations in the relative positions of oxygen atoms in the wire. In this diffusive mechanism, a shallow free-energy well slightly favors the presence of the excess proton near the middle of the channel. In the absence of H+, the water chain adopts either one of two polarized configurations, each of which corresponds to an oriented donor-acceptor hydrogen-bond pattern along the channel axis. Interconversion between these two conformations is an activated process that occurs through the sequential and directional reorientation of water molecules of the wire. The effect of hydrogen-bonding interactions between channel and water on proton translocation is analyzed from a comparison to the results obtained previously in a study of model nonpolar channels, in which such interactions were missing. Hydrogen-bond donation from water to the backbone carbonyl oxygen atoms lining the pore interior has a dual effect: it provides a coordination of water molecules well suited both to proton hydration and to high proton mobility, and it facilitates the slower reorientation or turn step of the Grotthuss mechanism by stabilizing intermediate configurations of the hydrogen-bonded network in which water molecules are in the process of flipping between their two preferred, polarized states. This mechanism offers a detailed molecular model for the rapid transport of protons in channels, in energy-transducing membrane proteins, and in enzymes.

Proton conducting membranes for high temperature fuel cells with solid state water free membranes

NASA Technical Reports Server (NTRS)

Narayanan, Sekharipuram R. (Inventor); Yen, Shiao-Pin S. (Inventor)

2006-01-01

A water free, proton conducting membrane for use in a fuel cell is fabricated as a highly conducting sheet of converted solid state organic amine salt, such as converted acid salt of triethylenediamine with two quaternized tertiary nitrogen atoms, combined with a nanoparticulate oxide and a stable binder combined with the converted solid state organic amine salt to form a polymeric electrolyte membrane. In one embodiment the membrane is derived from triethylenediamine sulfate, hydrogen phosphate or trifiate, an oxoanion with at least one ionizable hydrogen, organic tertiary amine bisulfate, polymeric quaternized amine bisulfate or phosphate, or polymeric organic compounds with quaternizable nitrogen combined with Nafion to form an intimate network with ionic interactions.

Novel Proton Conducting Solid Bio-polymer Electrolytes Based on Carboxymethyl Cellulose Doped with Oleic Acid and Plasticized with Glycerol

NASA Astrophysics Data System (ADS)

Chai, M. N.; Isa, M. I. N.

2016-06-01

The plasticized solid bio-polymer electrolytes (SBEs) system has been formed by introducing glycerol (Gly) as the plasticizer into the carboxymethyl cellulose (CMC) doped with oleic acid (OA) via solution casting techniques. The ionic conductivity of the plasticized SBEs has been studied using Electrical Impedance Spectroscopy. The highest conductivity achieved is 1.64 × 10-4 S cm-1 for system containing 40 wt. % of glycerol. FTIR deconvolution technique had shown that the conductivity of CMC-OA-Gly SBEs is primarily influenced by the number density of mobile ions. Transference number measurement has shown that the cation diffusion coefficient and ionic mobility is higher than anion which proved the plasticized polymer system is a proton conductor.

Memory and learning behaviors mimicked in nanogranular SiO2-based proton conductor gated oxide-based synaptic transistors

NASA Astrophysics Data System (ADS)

Wan, Chang Jin; Zhu, Li Qiang; Zhou, Ju Mei; Shi, Yi; Wan, Qing

2013-10-01

In neuroscience, signal processing, memory and learning function are established in the brain by modifying ionic fluxes in neurons and synapses. Emulation of memory and learning behaviors of biological systems by nanoscale ionic/electronic devices is highly desirable for building neuromorphic systems or even artificial neural networks. Here, novel artificial synapses based on junctionless oxide-based protonic/electronic hybrid transistors gated by nanogranular phosphorus-doped SiO2-based proton-conducting films are fabricated on glass substrates by a room-temperature process. Short-term memory (STM) and long-term memory (LTM) are mimicked by tuning the pulse gate voltage amplitude. The LTM process in such an artificial synapse is due to the proton-related interfacial electrochemical reaction. Our results are highly desirable for building future neuromorphic systems or even artificial networks via electronic elements.In neuroscience, signal processing, memory and learning function are established in the brain by modifying ionic fluxes in neurons and synapses. Emulation of memory and learning behaviors of biological systems by nanoscale ionic/electronic devices is highly desirable for building neuromorphic systems or even artificial neural networks. Here, novel artificial synapses based on junctionless oxide-based protonic/electronic hybrid transistors gated by nanogranular phosphorus-doped SiO2-based proton-conducting films are fabricated on glass substrates by a room-temperature process. Short-term memory (STM) and long-term memory (LTM) are mimicked by tuning the pulse gate voltage amplitude. The LTM process in such an artificial synapse is due to the proton-related interfacial electrochemical reaction. Our results are highly desirable for building future neuromorphic systems or even artificial networks via electronic elements. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr02987e

Joint neutron crystallographic and NMR solution studies of Tyr residue ionization and hydrogen bonding: Implications for enzyme-mediated proton transfer

DOE PAGES

Michalczyk, Ryszard; Unkefer, Clifford J.; Bacik, John -Paul; ...

2015-05-05

Proton transfer is a fundamental mechanism at the core of many enzyme-catalyzed reactions. It is also exquisitely sensitive to a number of factors, including pH, electrostatics, proper active-site geometry, and chemistry. Carbonic anhydrase has evolved a fast and efficient way to conduct protons through a combination of hydrophilic amino acid side chains that coordinate a highly ordered H-bonded water network. This study uses a powerful approach, combining NMR solution studies with neutron protein crystallography, to determine the effect of pH and divalent cations on key residues involved in proton transfer in human carbonic anhydrase. Lastly, the results have broad implicationsmore » for our understanding of proton transfer and how subtle changes in ionization and H-bonding interactions can modulate enzyme catalysis.« less

Proton Conduction in Tröger's Base Linked Poly(crown ether)s.

PubMed

Patel, Hasmukh A; Selberg, John; Salah, Dhafer; Chen, Haoyuan; Liao, Yijun; Nalluri, Siva Krishna Mohan; Farha, Omar K; Snurr, Randall Q; Rolandi, Marco; Stoddart, J Fraser

2018-06-05

Exactly 50 years ago, the ground-breaking discovery of dibenzo[18]crown-6 (DB18C6) by Charles Pedersen, led to the use of DB18C6 as a receptor in supramolecular chemistry and a host in host‒guest chemistry. We have demonstrated proton conductivity in Tröger's base-linked polymers through hydrogen-bonded networks formed from adsorbed water molecules on the oxygen atoms of DB18C6 under humid conditions. Tröger's base-linked polymers - poly(TBL‒DB18C6)-t and poly(TBL‒DB18C6)-c - synthesized by the in situ alkylation and cyclization of either trans- or cis-di(aminobenzo) [18]crown-6 at room temperature have been isolated as high molecular weight polymers. The macromolecular structures of the isomeric poly(TBL‒DB18C6)s have been established by spectroscopic techniques and size-exclusion chromatography. The excellent solubility of these polymers in chloroform allows the formation of free-standing membranes which are thermally stable and also show stability under aqueous conditions. The hydrophilic nature of the DB18C6 building blocks in the polymer facilitates retention of the water as confirmed by water-vapor adsorption isotherms which show a 23 wt% water uptake. The adsorbed water is retained even after reducing the relative humidity to 25 %. The proton conductivity of poly(TBL‒DB18C6)-t which is found to be 1.4 x 10‒4 mS cm‒1 in a humid environment, arises from the hydrogen bonding and the associated proton hopping mechanism, as supported by a modeling study. In addition to proton conductivity, the Tröger's base-linked polymers reported here promise a wide range of applications where the sub-nanometer-sized cavities of the crown ethers and the robust film-forming ability are the governing factors in dictating their properties.

Status of the Proton Therapy Project at IUCF and the Midwest Proton Radiotherapy Institute

NASA Astrophysics Data System (ADS)

Klein, Susan B.

2003-08-01

The first proton therapy patient was successfully treated for astrocytoma using a modified nuclear experimentation beam line and in-house treatment planning in 1993. In 1998, IUCF constructed an eye treatment clinic, and conducted a phase III clinical trial investigating proton radiation treatment of AMD. Treatment was planned using Eyeplan modified to match the IUCF beam characteristics. MPRI was conceptualized in 1996 by a consortium of physicians and physicists. Reconfiguration began in 2000; construction of the achromatic trunk line began in 2001, followed by manufacture of 4 energy selection lines and two fixed horizontal beam treatment lines. Two isocentric, rotational gantries will be installed following completion of the horizontal beam lines. A fifth line will supply the full-time radiation effects research station. Standard proton delivery out of the main stage is specified at 500 nA of 205 MeV. Clinic construction began in April, 2002 and will be completed by mid-December. Design, construction and operation of these proton facilities have been accomplished by the proton therapy group at IUCF.

Electromagnetic Cyclotron Waves in the Solar Wind: Wind Observation and Wave Dispersion Analysis

NASA Technical Reports Server (NTRS)

Jian, L. K.; Moya, P. S.; Vinas, A. F.; Stevens, M.

2016-01-01

Wind observed long-lasting electromagnetic cyclotron waves near the proton cyclotron frequency on 11 March 2005, in the descending part of a fast wind stream. Bi-Maxwellian velocity distributions are fitted for core protons, beam protons, and alpha-particles. Using the fitted plasma parameters we conduct kinetic linear dispersion analysis and find ion cyclotron and/or firehose instabilities grow in six of 10 wave intervals. After Doppler shift, some of the waves have frequency and polarization consistent with observation, thus may be correspondence to the cyclotron waves observed.

Electromagnetic cyclotron waves in the solar wind: Wind observation and wave dispersion analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jian, L. K., E-mail: lan.jian@nasa.gov; Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771; Moya, P. S.

2016-03-25

Wind observed long-lasting electromagnetic cyclotron waves near the proton cyclotron frequency on 11 March 2005, in the descending part of a fast wind stream. Bi-Maxwellian velocity distributions are fitted for core protons, beam protons, and α-particles. Using the fitted plasma parameters we conduct kinetic linear dispersion analysis and find ion cyclotron and/or firehose instabilities grow in six of 10 wave intervals. After Doppler shift, some of the waves have frequency and polarization consistent with observation, thus may be correspondence to the cyclotron waves observed.

High performance, durable polymers including poly(phenylene)

DOEpatents

Fujimoto, Cy; Pratt, Harry; Anderson, Travis Mark

2017-02-28

The present invention relates to functionalized polymers including a poly(phenylene) structure. In some embodiments, the polymers and copolymers of the invention include a highly localized concentration of acidic moieties, which facilitate proton transport and conduction through networks formed from these polymers. In addition, the polymers can include functional moieties, such as electron-withdrawing moieties, to protect the polymeric backbone, thereby extending its durability. Such enhanced proton transport and durability can be beneficial for any high performance platform that employs proton exchange polymeric membranes, such as in fuel cells or flow batteries.

Proton affinity of the histidine-tryptophan cluster motif from the influenza A virus from ab initio molecular dynamics

NASA Astrophysics Data System (ADS)

Bankura, Arindam; Klein, Michael L.; Carnevale, Vincenzo

2013-08-01

Ab initio molecular dynamics calculations have been used to compare and contrast the deprotonation reaction of a histidine residue in aqueous solution with the situation arising in a histidine-tryptophan cluster. The latter is used as a model of the proton storage unit present in the pore of the M2 proton conducting ion channel. We compute potentials of mean force for the dissociation of a proton from the Nδ and Nɛ positions of the imidazole group to estimate the pKas. Anticipating our results, we will see that the estimated pKa for the first protonation event of the M2 channel is in good agreement with experimental estimates. Surprisingly, despite the fact that the histidine is partially desolvated in the M2 channel, the affinity for protons is similar to that of a histidine in aqueous solution. Importantly, the electrostatic environment provided by the indoles is responsible for the stabilization of the charged imidazolium.

An evolutionarily conserved gene family encodes proton-selective ion channels.

PubMed

Tu, Yu-Hsiang; Cooper, Alexander J; Teng, Bochuan; Chang, Rui B; Artiga, Daniel J; Turner, Heather N; Mulhall, Eric M; Ye, Wenlei; Smith, Andrew D; Liman, Emily R

2018-03-02

Ion channels form the basis for cellular electrical signaling. Despite the scores of genetically identified ion channels selective for other monatomic ions, only one type of proton-selective ion channel has been found in eukaryotic cells. By comparative transcriptome analysis of mouse taste receptor cells, we identified Otopetrin1 (OTOP1), a protein required for development of gravity-sensing otoconia in the vestibular system, as forming a proton-selective ion channel. We found that murine OTOP1 is enriched in acid-detecting taste receptor cells and is required for their zinc-sensitive proton conductance. Two related murine genes, Otop2 and Otop3 , and a Drosophila ortholog also encode proton channels. Evolutionary conservation of the gene family and its widespread tissue distribution suggest a broad role for proton channels in physiology and pathophysiology. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Influence of protonation, tautomeric, and stereoisomeric states on protein-ligand docking results.

PubMed

ten Brink, Tim; Exner, Thomas E

2009-06-01

In this work, we present a systematical investigation of the influence of ligand protonation states, stereoisomers, and tautomers on results obtained with the two protein-ligand docking programs GOLD and PLANTS. These different states were generated with a fully automated tool, called SPORES (Structure PrOtonation and Recognition System). First, the most probable protonations, as defined by this rule based system, were compared to the ones stored in the well-known, manually revised CCDC/ASTEX data set. Then, to investigate the influence of the ligand protonation state on the docking results, different protonation states were created. Redocking and virtual screening experiments were conducted demonstrating that both docking programs have problems in identifying the correct protomer for each complex. Therefore, a preselection of plausible protomers or the improvement of the scoring functions concerning their ability to rank different molecules/states is needed. Additionally, ligand stereoisomers were tested for a subset of the CCDC/ASTEX set, showing similar problems regarding the ranking of these stereoisomers as the ranking of the protomers.

Influence of the Selectivity Filter Properties on Proton Selectivity in the Influenza A M2 Channel.

PubMed

Dudev, Todor; Grauffel, Cédric; Lim, Carmay

2016-10-05

The homotetrameric M2 proton channel of influenza A plays a crucial role in the viral life cycle and is thus an important therapeutic target. It selectively conducts protons against a background of other competing cations whose concentrations are up to a million times greater than the proton concentration. Its selectivity is largely determined by a constricted region of its open pore known as the selectivity filter, which is lined by four absolutely conserved histidines. While the mechanism of proton transport through the channel has been studied, the physical principles underlying the selectivity for protons over other cations in the channel's His 4 selectivity filter remain elusive. Furthermore, it is not known if proton selectivity absolutely requires all four histidines with two of the four histidines protonated and if other titratable amino acid residues in lieu of the histidines could bind protons and how they affect proton selectivity. Here, we elucidate how the competition between protons and rival cations such as Na + depends on the selectivity filter's (1) histidine protonation state, (2) solvent exposure, (3) oligomeric state (the number of protein chains and thus the number of His ligands), and (4) ligand composition by evaluating the free energies for replacing monovalent Na + with H 3 O + in various model selectivity filters. We show that tetrameric His 4 filters are more proton-selective than their trimeric His 3 counterparts, and a dicationic His 4 filter where two of the four histidines are protonated is more proton-selective than tetrameric filters with other charge states/composition (different combinations of His protonation states or different metal-ligating ligands). The [His 4 ] 2+ filter achieves proton selectivity by providing suboptimal binding conditions for rival cations such as Na + , which prefers a neutral or negatively charged filter instead of a dicationic one, and three rather than four ligands with oxygen-ligating atoms.

Characterization of proton conducting blend polymer electrolyte using PVA-PAN doped with NH{sub 4}SCN

DOE Office of Scientific and Technical Information (OSTI.GOV)

Premalatha, M.; Materials Research Center, Coimbatore-641 045; Mathavan, T., E-mail: tjmathavan@gmail.com, E-mail: kingslin.genova20@gmail.com

2016-05-23

Polymer electrolytes with proton conductivity based on blend polymer using polyvinyl alcohol (PVA) and poly acrylo nitrile (PAN) doped with ammonium thiocyanate have been prepared by solution casting method using DMF as solvent. The complex formation between the blend polymer and the salt has been confirmed by FTIR Spectroscopy. The amorphous nature of the blend polymer electrolytes have been confirmed by XRD analysis. The highest conductivity at 303 K has been found to be 3.25 × 10{sup −3} S cm{sup −1} for 20 mol % NH{sub 4}SCN doped 92.5PVA:7.5PAN system. The increase in conductivity of the doped blend polymer electrolytes with increasingmore » temperature suggests the Arrhenius type thermally activated process. The activation energy is found to be low (0.066 eV) for the highest conductivity sample.« less

High-temperature supercapacitor with a proton-conducting metal pyrophosphate electrolyte

PubMed Central

Hibino, Takashi; Kobayashi, Kazuyo; Nagao, Masahiro; Kawasaki, Shinji

2015-01-01

Expanding the range of supercapacitor operation to temperatures above 100°C is important because this would enable capacitors to operate under the severe conditions required for next-generation energy storage devices. In this study, we address this challenge by the fabrication of a solid-state supercapacitor with a proton-conducting Sn0.95Al0.05H0.05P2O7 (SAPO)-polytetrafluoroethylene (PTFE) composite electrolyte and a highly condensed H3PO4 electrode ionomer. At a temperature of 200°C, the SAPO-PTFE electrolyte exhibits a high proton conductivity of 0.02 S cm−1 and a wide withstanding voltage range of ±2 V. The H3PO4 ionomer also has good wettability with micropore-rich activated carbon, which realizes a capacitance of 210 F g−1 at 200°C. The resulting supercapacitor exhibits an energy density of 32 Wh kg−1 at 3 A g−1 and stable cyclability after 7000 cycles from room temperature to 150°C. PMID:25600936

Preparation of proton conducting membranes containing bifunctional titania nanoparticles

NASA Astrophysics Data System (ADS)

Aslan, Ayşe; Bozkurt, Ayhan

2013-07-01

Throughout this work, the synthesis and characterization of novel proton conducting nanocomposite membranes including binary and ternary mixtures of sulfated nano-titania (TS), poly(vinyl alcohol) (PVA), and nitrilotri(methyl phosphonic acid) (NMPA) are discussed. The materials were produced by means of two different approaches where in the first, PVA and TS (10-15 nm) were admixed to form a binary system. The second method was the ternary nanocomposite membranes including PVA/TS/NMPA that were prepared at several compositions to get PVA-TS-(NMPA) x . The interaction of functional nano particles and NMPA in the host matrix was explored by FT-IR spectroscopy. The homogeneous distribution of bifunctional nanoparticles in the membrane was confirmed by SEM micrographs. The spectroscopic measurements and water/methanol uptake studies suggested a complexation between PVA and NMPA, which inhibited the leaching of the latter. The thermogravimetry analysis results verified that the presence of TS in the composite membranes suppressed the formation of phosphonic acid anhydrides up to 150 °C. The maximum proton conductivity has been measured for PVA-TS-(NMPA)3 as 0.003 S cm-1 at 150 °C.

Infrared focal plane performance in the South Atlantic anomaly

NASA Technical Reports Server (NTRS)

Junga, Frank A.

1989-01-01

Proton-induced pulse height distributions (PHD's) in Si:XX detectors were studied analytically and experimentally. In addition, a preliminary design for a flight experiment to characterize the response of Si:XX detectors to the trapped proton environment and verify PHD models was developed. PHD's were computed for two orbit altitudes for a variety of shielding configurations. Most of the proton-induced pulses have amplitudes less that about 3.5 x 10(exp 5) e-h pairs. Shielding has a small effect on the shape of the PHD's. The primary effect of shielding is to reduce the total number of pulses produced. Proton-induced PHD's in a Si:Sb focal plane array bombarded by a unidirectional 67-MeV beam were measured. The maximum pulse height recorded was 6 x 10(exp 5) pairs. The distribution had two peaks: the larger peak corresponded to 3.8 x 10(exp 5) pairs and the smaller peak to 1.2 x 10(exp 5) pairs. The maximum pulse height and the larger peak are within a factor of two of predicted values. The low-energy peak was not expected, but is believed to be an artifact of inefficient charge collection in the detector. The planned flight experiment will be conducted on a Space Shuttle flight. Lockheed's helium extended life dewar (HELD) will be used to provide the required cryogenic environment for the detector. Two bulk Si:Sb arrays and two Si:As impurity band conduction arrays will be tested. The tests will be conducted while the Space Shuttle passes through the South Atlantic Anomaly. PHD's will be recorded and responsivity changes tracked. This experiment will provide a new database on proton-induced PHD's, compare two infrared detector technologies in a space environment, and provide the data necessary to validate PHD modeling.

A proton-exchange membrane prepared by the radiation grafting of styrene and silica into polytetrafluoroethylene films

NASA Astrophysics Data System (ADS)

Yu, Hongyan; Shi, Jianheng; Zeng, Xinmiao; Bao, Mao; Zhao, Xinqing

2009-07-01

A polytetrafluoroethylene (PTFE) based organic-inorganic hybrid proton-exchange membrane was prepared from simultaneous radiation grafting of styrene (St) into porous PTFE membrane with the in situ sol-gel reaction of tetraethoxysilane (TEOS) followed by sulfonation in fuming sulfonic acid. The effect of radiation on the sol-gel reaction was studied. The results show that radiation promotes the sol-gel reaction with the help of St at room temperature. Incorporated silica gel helps to produce higher degree of grafting (DOG). SEM analysis was conducted to confirm that the inorganic silicon oxide was introduced to produce hybrid membrane in this work. The proton conductivity of membrane evaluated using electrochemical impedance spectroscopy is much higher (14.3×10 -2 S cm -1) than that of Nafion ® 117 at temperature of 80 °C with acceptable water uptake 51 wt%.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wolf, Steffen; Gerwert, Klaus, E-mail: gerwert@bph.rub.de; Department of Biophysics, Chinese Academy of Sciences, Max-Planck-Gesellschaft Partner Institute for Computational Biology, 320 Yue Yang Road, 200031 Shanghai

Proton conduction along protein-bound “water wires” is an essential feature in membrane proteins. Here, we analyze in detail a transient water wire, which conducts protons via a hydrophobic barrier within a membrane protein to create a proton gradient. It is formed only for a millisecond out of three water molecules distributed at inactive positions in a polar environment in the ground state. The movement into a hydrophobic environment causes characteristic shifts of the water bands reflecting their different chemical properties. These band shifts are identified by time-resolved Fourier Transform Infrared difference spectroscopy and analyzed by biomolecular Quantum Mechanical/Molecular Mechanical simulations.more » A non-hydrogen bonded (“dangling”) O–H stretching vibration band and a broad continuum absorbance caused by a combined vibration along the water wire are identified as characteristic marker bands of such water wires in a hydrophobic environment. The results provide a basic understanding of water wires in hydrophobic environments.« less

Alkaline and non-aqueous proton-conducting pouch-cell batteries

DOEpatents

Young, Kwo-hsiung; Nei, Jean; Meng, Tiejun

2018-01-02

Provided are sealed pouch-cell batteries that are alkaline batteries or non-aqueous proton-conducing batteries. A pouch cell includes a flexible housing such as is used for pouch cell construction where the housing is in the form of a pouch, a cathode comprising a cathode active material suitable for use in an alkaline battery, an anode comprising an anode active material suitable for use in an alkaline battery, an electrolyte that is optionally an alkaline or proton-conducting electrolyte, and wherein the pouch does not include or require a safety vent or other gas absorbing or releasing system as the anode active material and the cathode active material do not increase the internal atmospheric pressure any more than 2 psig during cycling. The batteries provided function contrary to the art recognized belief that such battery systems were impossible due to unacceptable gas production during cycling.

Electrocatalysis-induced elasticity modulation in a superionic proton conductor probed by band-excitation atomic force microscopy.

PubMed

Papandrew, A B; Li, Q; Okatan, M B; Jesse, S; Hartnett, C; Kalinin, S V; Vasudevan, R K

2015-12-21

Variable temperature band-excitation atomic force microscopy in conjunction with I-V spectroscopy was used to investigate the crystalline superionic proton conductor CsHSO4 during proton exchange induced by a Pt-coated conductive scanning probe. At a sample temperature of 150 °C and under an applied bias <1 V, reduction currents of up to 1 nA were observed. Simultaneously, we show that the electrochemical reactions are accompanied by a reversible decrease in the elastic modulus of CsHSO4, as seen by a contact resonance shift, and find evidence for superplasticity during scanning. These effects were not observed in the room-temperature phase of CsHSO4 or in the case of catalytically inactive conductive probes, proving the utility of this technique for monitoring electrochemical processes on the nanoscale, as well as the use of local contact stiffness as a sensitive indicator of electrochemical reactions.

Proton transport in functionalised additives for PEM fuel cells: contributions from atomistic simulations.

PubMed

Tölle, Pia; Köhler, Christof; Marschall, Roland; Sharifi, Monir; Wark, Michael; Frauenheim, Thomas

2012-08-07

The conventional polymer electrolyte membrane (PEM) materials for fuel cell applications strongly rely on temperature and pressure conditions for optimal performance. In order to expand the range of operating conditions of these conventional PEM materials, mesoporous functionalised SiO(2) additives are developed. It has been demonstrated that these additives themselves achieve proton conductivities approaching those of conventional materials. However, the proton conduction mechanisms and especially factors influencing charge carrier mobility under different hydration conditions are not well known and difficult to separate from concentration effects in experiments. This tutorial review highlights contributions of atomistic computer simulations to the basic understanding and eventual design of these materials. Some basic introduction to the theoretical and computational framework is provided to introduce the reader to the field, the techniques are in principle applicable to a wide range of other situations as well. Simulation results are directly compared to experimental data as far as possible.

Infrared spectral marker bands characterizing a transient water wire inside a hydrophobic membrane protein.

PubMed

Wolf, Steffen; Freier, Erik; Cui, Qiang; Gerwert, Klaus

2014-12-14

Proton conduction along protein-bound "water wires" is an essential feature in membrane proteins. Here, we analyze in detail a transient water wire, which conducts protons via a hydrophobic barrier within a membrane protein to create a proton gradient. It is formed only for a millisecond out of three water molecules distributed at inactive positions in a polar environment in the ground state. The movement into a hydrophobic environment causes characteristic shifts of the water bands reflecting their different chemical properties. These band shifts are identified by time-resolved Fourier Transform Infrared difference spectroscopy and analyzed by biomolecular Quantum Mechanical/Molecular Mechanical simulations. A non-hydrogen bonded ("dangling") O-H stretching vibration band and a broad continuum absorbance caused by a combined vibration along the water wire are identified as characteristic marker bands of such water wires in a hydrophobic environment. The results provide a basic understanding of water wires in hydrophobic environments.

Influence of the Level of Protonation on the Geometry and the Electronic Structure of Emeraldine Oligomers

NASA Astrophysics Data System (ADS)

Petrova, Jasmina; Romanova, Julia; Madjarova, Galia; Ivanova, Anela; Tadjer, Alia; Gospodinova, Natalia

A number of studies prove the existence of magnetically active states in polyaniline and claim polaronic nature of conductivity, but the molecular structure of polarons and bipolarons with account of the solvent effect has not been exhausted. Alongside with conductivity, the optical and magnetic properties of the polymer related to its practical application could be rationalized by the elucidation of this problem. The purpose of this chapter is the assessment of the degree of protonation on the spatial and electronic structure of hydrated polyaniline oligomers. Neutral and protonated emeraldine octamers are modeled to this end. UHF, UBLYP, and UB3LYP with 6-31G* basis set were employed for optimization of the geometry in aqueous medium (PCM). Various structural parameters: bond lengths, valence, and torsion angles, were analyzed and compared. The distribution of Mulliken and NBO charge density and Mulliken atomic spin density was discussed.

Proton transport through aqueous Nafion membrane

NASA Astrophysics Data System (ADS)

Son, D. N.; Kasai, H.

2009-08-01

We introduce a new model for proton transport through a single proton-conducting channel of an aqueous Nafion membrane based on a mechanism in which protons move under electrostatic effect provided by the sulfonate ( SO3 -groups of the Nafion side chains, the spin effect of active components, the hydrogen bonding effect with water molecules, and the screening effect of water media. This model can describe the proton transport within various levels of humidification ranging from the low humidity to the high humidity as a function of operating temperature. At low humidity, this model approaches to the so-called surface mechanism, while at high humidity, it approaches the well-known Grotthuss one. Proton motion is considered as the transfer from cluster to cluster under a potential energy. A proton-proton interaction is comprised in the calculation. Using Green function method, we obtained the proton current as a function of the Nafion membrane temperature. We found that the lower the temperature, the higher the proton current transfer through the Nafion membrane in low temperatures compared to the critical point 10K, which separates magnetic regime from non-magnetic regime. The increasing of proton current at very low temperatures is attributed to the spin effect. As the membrane temperature is higher than 40 ° C , the decreasing of proton current is attributed to the loss of water uptake and the polymer contraction. The results of this study are qualitatively in good agreement with experiments. The expression for the critical temperature is also presented as a function of structural and tunable parameters, and interpreted by experimental data. in here

Modification of the argon stripping target of the tandem accelerator.

PubMed

Makarov, A; Ostreinov, Yu; Taskaev, S; Vobly, P

2015-12-01

The tandem accelerator with vacuum insulation has been proposed and developed in Budker Institute of Nuclear Physics. Negative hydrogen ions are accelerated by the positive 1MV potential of the high-voltage electrode, converted into protons in the gas stripping target inside the electrode, and then protons are accelerated again by the same potential. A stationary proton beam with 2 MeV energy, 1.6 mA current, 0.1% energy monochromaticity, and 0.5% current stability is obtained now. To conduct Boron Neutron Capture Therapy it is planned to increase the proton beam current to at least 3 mA. The paper presents the results of experimental studies clarifying the reasons for limiting the current, and gives suggestions for modifying the gas stripping target in order to increase the proton beam current along with the stability of the accelerator. Copyright © 2015 Elsevier Ltd. All rights reserved.

Protons Regulate Vesicular Glutamate Transporters through an Allosteric Mechanism.

PubMed

Eriksen, Jacob; Chang, Roger; McGregor, Matt; Silm, Katlin; Suzuki, Toshiharu; Edwards, Robert H

2016-05-18

The quantal nature of synaptic transmission requires a mechanism to transport neurotransmitter into synaptic vesicles without promoting non-vesicular efflux across the plasma membrane. Indeed, the vesicular transport of most classical transmitters involves a mechanism of H(+) exchange, which restricts flux to acidic membranes such as synaptic vesicles. However, vesicular transport of the principal excitatory transmitter glutamate depends primarily on membrane potential, which would drive non-vesicular efflux, and the role of protons is unclear. Adapting electrophysiology to record currents associated with the vesicular glutamate transporters (VGLUTs), we characterize a chloride conductance that is gated by lumenal protons and chloride and supports glutamate uptake. Rather than coupling stoichiometrically to glutamate flux, lumenal protons and chloride allosterically activate vesicular glutamate transport. Gating by protons serves to inhibit what would otherwise be substantial non-vesicular glutamate efflux at the plasma membrane, thereby restricting VGLUT activity to synaptic vesicles. Copyright © 2016 Elsevier Inc. All rights reserved.

Reaction of the high-latitude lower ionosphere to solar proton events from observations in the ELF range

NASA Astrophysics Data System (ADS)

Lebed', O. M.; Larchenko, A. V.; Pil'gaev, S. V.; Fedorenko, Yu. V.

2017-01-01

The reaction of the lower ionosphere to the solar proton events that occurred in 2011-2012 is studied in this paper based on the results of measurements of the propagation velocity and the E z / H τ ratio of the low-frequency electromagnetic pulses (atmospherics) in the ELF range at the high-latitude observatories Lovozero and Barentsburg. With numerical modeling methods, it is shown that horizontal local irregularities of the lower ionosphere conductivity profile could be a cause of the splashes in the E z / H τ ratio observed in the experiment during the solar proton event of March 7, 2012, which was a unique event in both the proton flux value and energy.

The calcium-permeable non-selective cation channel TRPM2 is modulated by cellular acidification

PubMed Central

Starkus, John G; Fleig, Andrea; Penner, Reinhold

2010-01-01

TRPM2 is a calcium-permeable non-selective cation channel expressed in the plasma membrane and in lysosomes that is critically involved in aggravating reactive oxygen species (ROS)-induced inflammatory processes and has been implicated in cell death. TRPM2 is gated by ADP-ribose (ADPR) and modulated by physiological processes that produce peroxide, cyclic ADP-ribose (cADPR), nicotinamide adenine dinucleotide phosphate (NAADP) and Ca2+. We investigated the role of extra- and intracellular acidification on heterologously expressed TRPM2 in HEK293 cells. Our results show that TRPM2 is inhibited by external acidification with an IC50 of pH 6.5 and is completely suppressed by internal pH of 6. Current inhibition requires channel opening and is strongly voltage dependent, being most effective at negative potentials. In addition, increased cytosolic pH buffering capacity or elevated [Ca2+]i reduces the rate of current inactivation elicited by extracellular acidification, and Na+ and Ca2+ influence the efficacy of proton-induced inactivation. Together, these results suggest that external protons permeate TRPM2 channels to gain access to an intracellular site that regulates channel activity. Consistent with this notion, single-channel measurements in HEK293 cells reveal that internal protons induce channel closure without affecting single-channel conductance, whereas external protons affect channel open probability as well as single-channel conductance of native TRPM2 in neutrophils. We conclude that protons compete with Na+ and Ca2+ for channel permeation and channel closure results from a competitive antagonism of protons at an intracellular Ca2+ binding site. PMID:20194125

The calcium-permeable non-selective cation channel TRPM2 is modulated by cellular acidification.

PubMed

Starkus, John G; Fleig, Andrea; Penner, Reinhold

2010-04-15

TRPM2 is a calcium-permeable non-selective cation channel expressed in the plasma membrane and in lysosomes that is critically involved in aggravating reactive oxygen species (ROS)-induced inflammatory processes and has been implicated in cell death. TRPM2 is gated by ADP-ribose (ADPR) and modulated by physiological processes that produce peroxide, cyclic ADP-ribose (cADPR), nicotinamide adenine dinucleotide phosphate (NAADP) and Ca(2+). We investigated the role of extra- and intracellular acidification on heterologously expressed TRPM2 in HEK293 cells. Our results show that TRPM2 is inhibited by external acidification with an IC(50) of pH 6.5 and is completely suppressed by internal pH of 6. Current inhibition requires channel opening and is strongly voltage dependent, being most effective at negative potentials. In addition, increased cytosolic pH buffering capacity or elevated [Ca(2+)](i) reduces the rate of current inactivation elicited by extracellular acidification, and Na(+) and Ca(2+) influence the efficacy of proton-induced inactivation. Together, these results suggest that external protons permeate TRPM2 channels to gain access to an intracellular site that regulates channel activity. Consistent with this notion, single-channel measurements in HEK293 cells reveal that internal protons induce channel closure without affecting single-channel conductance, whereas external protons affect channel open probability as well as single-channel conductance of native TRPM2 in neutrophils. We conclude that protons compete with Na(+) and Ca(2+) for channel permeation and channel closure results from a competitive antagonism of protons at an intracellular Ca(2+) binding site.

Inorganic proton conducting electrolyte coupled oxide-based dendritic transistors for synaptic electronics.

PubMed

Wan, Chang Jin; Zhu, Li Qiang; Zhou, Ju Mei; Shi, Yi; Wan, Qing

2014-05-07

Ionic/electronic hybrid devices with synaptic functions are considered to be the essential building blocks for neuromorphic systems and brain-inspired computing. Here, artificial synapses based on indium-zinc-oxide (IZO) transistors gated by nanogranular SiO2 proton-conducting electrolyte films are fabricated on glass substrates. Spike-timing dependent plasticity and paired-pulse facilitation are successfully mimicked in an individual bottom-gate transistor. Most importantly, dynamic logic and dendritic integration established by spatiotemporally correlated spikes are also mimicked in dendritic transistors with two in-plane gates as the presynaptic input terminals.

Voltage-Gated Proton Channels: Molecular Biology, Physiology, and Pathophysiology of the HV Family

PubMed Central

2013-01-01

Voltage-gated proton channels (HV) are unique, in part because the ion they conduct is unique. HV channels are perfectly selective for protons and have a very small unitary conductance, both arguably manifestations of the extremely low H+ concentration in physiological solutions. They open with membrane depolarization, but their voltage dependence is strongly regulated by the pH gradient across the membrane (ΔpH), with the result that in most species they normally conduct only outward current. The HV channel protein is strikingly similar to the voltage-sensing domain (VSD, the first four membrane-spanning segments) of voltage-gated K+ and Na+ channels. In higher species, HV channels exist as dimers in which each protomer has its own conduction pathway, yet gating is cooperative. HV channels are phylogenetically diverse, distributed from humans to unicellular marine life, and perhaps even plants. Correspondingly, HV functions vary widely as well, from promoting calcification in coccolithophores and triggering bioluminescent flashes in dinoflagellates to facilitating killing bacteria, airway pH regulation, basophil histamine release, sperm maturation, and B lymphocyte responses in humans. Recent evidence that hHV1 may exacerbate breast cancer metastasis and cerebral damage from ischemic stroke highlights the rapidly expanding recognition of the clinical importance of hHV1. PMID:23589829

Effect of proton-conduction in electrolyte on electric efficiency of multi-stage solid oxide fuel cells

PubMed Central

Matsuzaki, Yoshio; Tachikawa, Yuya; Somekawa, Takaaki; Hatae, Toru; Matsumoto, Hiroshige; Taniguchi, Shunsuke; Sasaki, Kazunari

2015-01-01

Solid oxide fuel cells (SOFCs) are promising electrochemical devices that enable the highest fuel-to-electricity conversion efficiencies under high operating temperatures. The concept of multi-stage electrochemical oxidation using SOFCs has been proposed and studied over the past several decades for further improving the electrical efficiency. However, the improvement is limited by fuel dilution downstream of the fuel flow. Therefore, evolved technologies are required to achieve considerably higher electrical efficiencies. Here we present an innovative concept for a critically-high fuel-to-electricity conversion efficiency of up to 85% based on the lower heating value (LHV), in which a high-temperature multi-stage electrochemical oxidation is combined with a proton-conducting solid electrolyte. Switching a solid electrolyte material from a conventional oxide-ion conducting material to a proton-conducting material under the high-temperature multi-stage electrochemical oxidation mechanism has proven to be highly advantageous for the electrical efficiency. The DC efficiency of 85% (LHV) corresponds to a net AC efficiency of approximately 76% (LHV), where the net AC efficiency refers to the transmission-end AC efficiency. This evolved concept will yield a considerably higher efficiency with a much smaller generation capacity than the state-of-the-art several tens-of-MW-class most advanced combined cycle (MACC). PMID:26218470

Effect of proton-conduction in electrolyte on electric efficiency of multi-stage solid oxide fuel cells.

PubMed

Matsuzaki, Yoshio; Tachikawa, Yuya; Somekawa, Takaaki; Hatae, Toru; Matsumoto, Hiroshige; Taniguchi, Shunsuke; Sasaki, Kazunari

2015-07-28

Solid oxide fuel cells (SOFCs) are promising electrochemical devices that enable the highest fuel-to-electricity conversion efficiencies under high operating temperatures. The concept of multi-stage electrochemical oxidation using SOFCs has been proposed and studied over the past several decades for further improving the electrical efficiency. However, the improvement is limited by fuel dilution downstream of the fuel flow. Therefore, evolved technologies are required to achieve considerably higher electrical efficiencies. Here we present an innovative concept for a critically-high fuel-to-electricity conversion efficiency of up to 85% based on the lower heating value (LHV), in which a high-temperature multi-stage electrochemical oxidation is combined with a proton-conducting solid electrolyte. Switching a solid electrolyte material from a conventional oxide-ion conducting material to a proton-conducting material under the high-temperature multi-stage electrochemical oxidation mechanism has proven to be highly advantageous for the electrical efficiency. The DC efficiency of 85% (LHV) corresponds to a net AC efficiency of approximately 76% (LHV), where the net AC efficiency refers to the transmission-end AC efficiency. This evolved concept will yield a considerably higher efficiency with a much smaller generation capacity than the state-of-the-art several tens-of-MW-class most advanced combined cycle (MACC).

Electrochemical Approach for Analyzing Electrolyte Transport Properties and Their Effect on Protonic Ceramic Fuel Cell Performance.

PubMed

Danilov, Nikolay; Lyagaeva, Julia; Vdovin, Gennady; Medvedev, Dmitry; Demin, Anatoly; Tsiakaras, Panagiotis

2017-08-16

The design and development of highly conductive materials with wide electrolytic domain boundaries are among the most promising means of enabling solid oxide fuel cells (SOFCs) to demonstrate outstanding performance across low- and intermediate-temperature ranges. While reducing the thickness of the electrolyte is an extensively studied means for diminishing the total resistance of SOFCs, approaches involving an improvement in the transport behavior of the electrolyte membranes have been less-investigated. In the present work, a strategy for analyzing the electrolyte properties and their effect on SOFC output characteristics is proposed. To this purpose, a SOFC based on a recently developed BaCe 0.5 Zr 0.3 Dy 0.2 O 3-δ proton-conducting ceramic material was fabricated and tested. The basis of the strategy consists of the use of traditional SOFC testing techniques combined with the current interruption method and electromotive force measurements with a modified polarization-correction assessment. This allows one to determine simultaneously such important parameters as maximal power density; ohmic and polarization resistances; average ion transport numbers; and total, ionic, and electronic film conductivities and their activation energies. The proposed experimental procedure is expected to expand both fundamental and applied basics that could be further adopted to improve the technology of electrochemical devices based on proton-conducting electrolytes.

Test report: Shock test of the electron/proton spectrometer structural test unit

NASA Technical Reports Server (NTRS)

Vincent, D. L.

1972-01-01

A shock test of the electron-proton spectrometer structural test unit was conducted. The purpose of the shock test was to verify the structural integrity of the electron-spectrometer design and to obtain data on the shock response of the electronics and electronic housing. The test equipment is described and typical shock response data are provided.

Effect of "bridge" on the performance of organic-inorganic crosslinked hybrid proton exchange membranes via KH550

NASA Astrophysics Data System (ADS)

Han, Hailan; Li, Hai Qiang; Liu, Meiyu; Xu, Lishuang; Xu, Jingmei; Wang, Shuang; Ni, Hongzhe; Wang, Zhe

2017-02-01

A series of novel organic-inorganic crosslinked hybrid proton exchange membranes were prepared using sulfonated poly(arylene ether ketone sulfone) polymers containing carboxyl groups (C-SPAEKS), (3-aminopropyl)-triethoxysilane (KH550), and tetraethoxysilane (TEOS). KH550 acted as a "bridge" after reacting with carboxyl and sulfonic groups of C-SPAEKS to form covalent and ionic crosslinked structure between the C-SPAEKS and SiO2 phase. The crosslinked hybrid membranes (C-SPAEKS/K-SiO2) were characterized by FT-IR spectroscopy, TGA, and electrochemistry, etc. The thermal stability, mechanical properties and proton conductivity of the crosslinked hybrid membranes were improved by the presence of both crosslinked structure and inorganic phase. The proton conductivity of C-SPAEKS/K-SiO2-8 was recorded as 0.110 S cm-1, higher than that of Nafion® (0.028 S cm-1) at 120 °C. Moreover, the methanol permeability of the C-SPAEKS/K-SiO2-8 was measured as 3.86 × 10-7 cm2 s-1, much lower than that of Nafion® 117 membranes (29.4 × 10-7 cm2 s-1) at 25 °C.

Ion pair reinforced semi-interpenetrating polymer network for direct methanol fuel cell applications.

PubMed

Fang, Chunliu; Julius, David; Tay, Siok Wei; Hong, Liang; Lee, Jim Yang

2012-06-07

This paper describes the synthesis of ion-pair-reinforced semi-interpenetrating polymer networks (SIPNs) as proton exchange membranes (PEMs) for the direct methanol fuel cells (DMFCs). Specifically, sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) (SPPO), a linear polymer proton source, was immobilized in a brominated PPO (BPPO) network covalently cross-linked by ethylenediamine (EDA). The immobilization of SPPO in the SIPN network was accomplished not only by the usual means of mechanical interlocking but also by ion pair formation between the sulfonic acid groups of SPPO and the amine moieties formed during the cross-linking reaction of BPPO with EDA. Through the ion pair interactions, the immobilization of SPPO polymer in the BPPO network was made more effective, resulting in a greater uniformity of sulfonic acid cluster distribution in the membrane. The hydrophilic amine-containing cross-links also compensated for some of the decrease in proton conductivity caused by ion pair formation. The SIPN membranes prepared as such showed good proton conductivity, low methanol permeability, good mechanical properties, and dimensional stability. Consequently, the PPO based SIPN membranes were able to deliver a higher maximum power density than Nafion, demonstrating the potential of the SIPN structure for PEM designs.

Proton emission from cone-in-shell fast-ignition experiments at Omega

NASA Astrophysics Data System (ADS)

Sinenian, N.; Theobald, W.; Frenje, J. A.; Stoeckl, C.; Séguin, F. H.; Li, C. K.; Petrasso, R. D.; Stephens, R. B.

2012-11-01

Measurements of energetic protons from cone-in-shell fast-igniton implosions at Omega have been conducted. In these experiments, charged-particle spectrometers were used to measure a significant population (>1013) of energetic protons (7.5 MeV max.), indicating the presence of strong electric fields. These energetic protons, observed in directions both transverse and forward relative to the direction of the short-pulse laser beam, have been used to study aspects of coupling efficiency of the petawatt fast-ignitior beam. Approximately 5% of the laser energy coupled to hot electrons was lost to fast ions. Forward going protons were less energetic and showed no dependence on laser intensity or whether the cone tip was intact when the short-pulse laser was fired. Maximum energies of protons emitted transverse to the cone-in-shell target scale with incident on-target laser intensity (2-6×1018W-cm-2), as described by the ponderomotive scaling (∝I1/2). It is shown that these protons are accelerated from the entire cone, rather than from the cone tip alone. These protons were used to estimate the lower limit on the hot-electron temperature, which was found to be hotter than the ponderomotive scaling by factors of 2-3.

Induction of Cell Death through Alteration of Oxidants and Antioxidants in Epithelial Cells Exposed to High Energy Protons

NASA Technical Reports Server (NTRS)

Ramesh, Govindarajan; Wu, Honglu

2012-01-01

Radiation affects several cellular and molecular processes including double strand breakage, modifications of sugar moieties and bases. In outer space, protons are the primary radiation source which poses a range of potential health risks to astronauts. On the other hand, the use of proton radiation for tumor radiation therapy is increasing as it largely spares healthy tissues while killing tumor tissues. Although radiation related research has been conducted extensively, the molecular toxicology and cellular mechanisms affected by proton radiation remain poorly understood. Therefore, in the present study, we irradiated rat epithelial cells (LE) with different doses of protons and investigated their effects on cell proliferation and cell death. Our data showed an inhibition of cell proliferation in proton irradiated cells with a significant dose dependent activation and repression of reactive oxygen species (ROS) and antioxidants, glutathione and superoxide dismutase respectively as compared to control cells. In addition, apoptotic related genes such as caspase-3 and -8 activities were induced in a dose dependent manner with corresponding increased levels of DNA fragmentation in proton irradiated cells than control cells. Together, our results show that proton radiation alters oxidant and antioxidant levels in the cells to activate apoptotic pathway for cell death.

Electron Nuclear Dynamics Simulations of Proton Cancer Therapy Reactions: Water Radiolysis and Proton- and Electron-Induced DNA Damage in Computational Prototypes.

PubMed

Teixeira, Erico S; Uppulury, Karthik; Privett, Austin J; Stopera, Christopher; McLaurin, Patrick M; Morales, Jorge A

2018-05-06

Proton cancer therapy (PCT) utilizes high-energy proton projectiles to obliterate cancerous tumors with low damage to healthy tissues and without the side effects of X-ray therapy. The healing action of the protons results from their damage on cancerous cell DNA. Despite established clinical use, the chemical mechanisms of PCT reactions at the molecular level remain elusive. This situation prevents a rational design of PCT that can maximize its therapeutic power and minimize its side effects. The incomplete characterization of PCT reactions is partially due to the health risks associated with experimental/clinical techniques applied to human subjects. To overcome this situation, we are conducting time-dependent and non-adiabatic computer simulations of PCT reactions with the electron nuclear dynamics (END) method. Herein, we present a review of our previous and new END research on three fundamental types of PCT reactions: water radiolysis reactions, proton-induced DNA damage and electron-induced DNA damage. These studies are performed on the computational prototypes: proton + H₂O clusters, proton + DNA/RNA bases and + cytosine nucleotide, and electron + cytosine nucleotide + H₂O. These simulations provide chemical mechanisms and dynamical properties of the selected PCT reactions in comparison with available experimental and alternative computational results.

Deep Dielectric Charging of Spacecraft Polymers by Energetic Protons

NASA Technical Reports Server (NTRS)

Green, Nelson W.; Dennison, J. R.

2007-01-01

The majority of research in the field of spacecraft charging concentrates on electron charging effects with little discussion of charging by protons. For spacecraft orbiting in the traditional LEO and GEO environments this emphasis on electrons is appropriate since energetic electrons are the dominant species in those orbits. But for spacecraft in orbits within the inner radiation belts or for interplanetary and lunar space probes, proton charging (center dot) effects may also be of concern. To examine bulk spacecraft charging effects in these environments several typical highly insulating spacecraft polymers were exposed to energetic protons (center dot) with energies from 1 Me V to lO Me V to simulate protons from the solar wind and from solar energetic proton events. Results indicate that effects in proton charged dielectrics are distinctly different than those observed due to electron charging. In most cases, the positive surface potential continued to increase for periods on the order of minutes to a day, followed by long time scale decay at rates similar to those observed for electron charging. All samples charged to positive potentials with substantially lower magnitudes than for equivalent electron doses. Possible explanations for the different behavior of the measured surface potentials from proton irradiation are discussed; these are related to the evolving internal charge distribution from energy dependent electron and proton transport, electron emission, charge migration due to dark current and radiation induced conductivity, and electron capture by embedded protons.

Absence of uncoupling protein-3 leads to greater activation of an adenine nucleotide translocase-mediated proton conductance in skeletal muscle mitochondria from calorie restricted mice.

PubMed

Bevilacqua, Lisa; Seifert, Erin L; Estey, Carmen; Gerrits, Martin F; Harper, Mary-Ellen

2010-08-01

Calorie restriction (CR), without malnutrition, consistently increases lifespan in all species tested, and reduces age-associated pathologies in mammals. Alterations in mitochondrial content and function are thought to underlie some of the effects of CR. Previously, we reported that rats subjected to variable durations of 40% CR demonstrated a rapid and sustained decrease in maximal leak-dependent respiration in skeletal muscle mitochondria. This was accompanied by decreased mitochondrial reactive oxygen species generation and increased uncoupling protein-3 protein (UCP3) expression. The aim of the present study was to determine the contribution of UCP3, as well as the adenine nucleotide translocase to these functional changes in skeletal muscle mitochondria. Consistent with previous findings in rats, short-term CR (2 weeks) in wild-type (Wt) mice resulted in a lowering of the maximal leak-dependent respiration in skeletal muscle mitochondria, without any change in proton conductance. In contrast, skeletal muscle mitochondria from Ucp3-knockout (KO) mice similarly subjected to short-term CR showed no change in maximal leak-dependent respiration, but displayed an increased proton conductance. Determination of ANT activity (by measurement of inhibitor-sensitive leak) and protein expression revealed that the increased proton conductance in mitochondria from CR Ucp3-KO mice could be entirely attributed to a greater acute activation of ANT. These observations implicate UCP3 in CR-induced mitochondrial remodeling. Specifically, they imply the potential for an interaction, or some degree of functional redundancy, between UCP3 and ANT, and also suggest that UCP3 can minimize the induction of the ANT-mediated 'energy-wasting' process during CR. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Low-dose or standard-dose proton pump inhibitors for maintenance therapy of gastro-oesophageal reflux disease: a cost-effectiveness analysis.

PubMed

You, J H S; Lee, A C M; Wong, S C Y; Chan, F K L

2003-03-15

Studies on the use of low-dose proton pump inhibitor for the maintenance therapy of gastro-oesophageal reflux disease have shown that it might be comparable with standard-dose proton pump inhibitor treatment and superior to standard-dose histamine-2 receptor antagonist therapy. To compare the impact of standard-dose histamine-2 receptor antagonist, low-dose proton pump inhibitor and standard-dose proton pump inhibitor treatment for the maintenance therapy of gastro-oesophageal reflux disease on symptom control and health care resource utilization from the perspective of a public health organization in Hong Kong. A Markov model was designed to simulate, over 12 months, the economic and clinical outcomes of gastro-oesophageal reflux disease patients treated with standard-dose histamine-2 receptor antagonist, low-dose proton pump inhibitor and standard-dose proton pump inhibitor. The transition probabilities were derived from the literature. Resource utilization was retrieved from a group of gastro-oesophageal reflux disease patients in Hong Kong. Sensitivity analysis was conducted to examine the robustness of the model. The standard-dose proton pump inhibitor strategy was associated with the highest numbers of symptom-free patient-years (0.954 years) and quality-adjusted life-years gained (0.999 years), followed by low-dose proton pump inhibitor and standard-dose histamine-2 receptor antagonist. The direct medical cost per patient in the standard-dose proton pump inhibitor group (904 US dollars) was lower than those of the low-dose proton pump inhibitor and standard-dose histamine-2 receptor antagonist groups. The standard-dose proton pump inhibitor strategy appears to be the most effective and least costly for the maintenance management of patients with gastro-oesophageal reflux disease in Hong Kong.

Hydrogen-Bonded Network and Water Dynamics in the D-channel of Cytochrome c Oxidase.

PubMed

Ghane, Tahereh; Gorriz, Rene F; Wrzalek, Sandro; Volkenandt, Senta; Dalatieh, Ferand; Reidelbach, Marco; Imhof, Petra

2018-02-12

Proton transfer in cytochrome c oxidase (CcO) from the cellular inside to the binuclear redox centre as well as proton pumping through the membrane takes place through proton entrance via two distinct pathways, the D- and K-channel. Both channels show a dependence of their hydration level on the protonation states of their key residues, K362 for the K-channel, and E286 or D132 for the D-channel. In the oxidative half of CcO's catalytic cycle the D-channel is the proton-conducting path. For this channel, an interplay of protonation state of the D-channel residues with the water and hydrogen-bond dynamics has been observed in molecular dynamics simulations of the CcO protein, embedded in a lipid bi-layer, modelled in different protonation states. Protonation of residue E286 at the end of the D-channel results in a hydrogen-bonded network pointing from E286 to N139, that is against proton transport, and favouring N139 conformations which correspond to a closed asparagine gate (formed by residues N121 and N139). Consequently, the hydration level is lower than with unprotonated E286. In those models, the Asn gate is predominantly open, allowing water molecules to pass and thus increase the hydration level. The hydrogen-bonded network in these states exhibits longer life times of the Asn residues with water than other models and shows the D-channel to be traversable from the entrance, D132, to exit, E286. The D-channel can thus be regarded as auto-regulated with respect to proton transport, allowing proton passage only when required, that is the proton is located at the lower part of the D-channel (D132 to Asn gate) and not at the exit (E286).

Measurements of Gas and Particle Phase Emissions From Munitions Detonation in a Field Environment

NASA Astrophysics Data System (ADS)

Fortner, E. C.; Knighton, W. B.; Timko, M.; Wood, E.; Onasch, T. B.; Kolb, C. E.; Beardsley, H. M.

2007-12-01

During the Point of Fire (POF) field campaign conducted at Fort Sill Oklahoma U.S.A. in March 2007 a suite of real- time trace gas and fine (submicron) particulate matter (PM) instrumentation characterized the point of fire emission plumes from large, medium and small caliber weapons systems. Muzzle emission plumes were measured and where appropriate, breach plumes and gun crew breathing zone measurements were also conducted. Aerosol measurements were conducted with an aerosol mass spectrometer (Aerodyne CTOF-AMS) for particle composition, condensation particle counter (CPC) for particle number density and DUSTRAK aerosol monitor for particle mass. Gas phase measurements included CO, CO2, NOx and a variety of trace gas species measured by proton transfer reaction mass spectrometry (PTR-MS) including hydrogen cyanide (HCN), acetonitrile, acrylonitrile, benzene, toluene, benzonitrile and styrene. In the majority of the plume measurements, HCN was the most prominent compound measured by PTR-MS. Quantification of HCN by PTR-MS is difficult due to its proton affinity being close enough to that of water to allow a significant backward reaction of protonated HCN with water, reducing the detection sensitivity and making the response dependent on humidity. We have developed a quantification procedure for HCN based on laboratory measurements of a calibration gas standard of HCN, which allows the humidity dependence to be extracted directly from the proton hydrate ion intensities. The correction factors for HCN are quite significant varying between 10 and 30 depending on sample humidity.

Improvement of electrochemical performances of sulfonated poly(arylene ether sulfone) via incorporation of sulfonated poly(arylene ether benzimidazole)

NASA Astrophysics Data System (ADS)

Hong, Young Taik; Lee, Chang Hyun; Park, Hyung Su; Min, Kyung A.; Kim, Hyung Joong; Nam, Sang Yong; Lee, Young Moo

In the present study, modified acid-base blend membranes were fabricated via incorporation of sulfonated poly(arylene ether benzimidazole) (SPAEBI) into sulfonated poly(arylene ether sulfone) (SPAES). These membranes had excellent methanol-barrier properties in addition to an ability to compensate for the loss of proton conductivity that typically occurs in general acid-base blend system. To fabricate the membranes, SPAEBIs, which served as amphiphilic polymers with different degrees of sulfonation (0-50 mol%), were synthesized by polycondensation and added to SPAES. It resulted in the formation of acid-amphiphilic complexes such as [PAES-SO 3] - +[H-SPAEBI] through the ionic crosslinking, which prevented SO 3H groups in the complex from transporting free protons in an aqueous medium, contributing to a reduction of ion exchange capacity values and water uptake in the blend membranes, and leading to lower methanol permeability in a water-methanol mixture. Unfortunately, the ionic bonding formation was accompanied by a decrease of bound water content and proton conductivity, although the latter problem was solved to some extent by the incorporation of additional SO 3H groups in SPAEBI. In the SPAES-SPAEBI blend membranes, enhancement of proton conductivity and methanol-barrier property was prominent at temperatures over 90 °C. The direct methanol fuel cell (DMFC) performance, which was based on SPAES-SPAEBI-50-5, was 1.2 times higher than that of Nafion ® 117 under the same operating condition.

Search for new physics in the monophoton final state in proton-proton collisions at sqrt(s) = 13 TeV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sirunyan, Albert M; et al.

2017-06-12

A search is conducted for new physics in a final state containing a photon and missing transverse momentum in proton-proton collisions at sqrt(s) = 13 TeV. The data collected by the CMS experiment at the CERN LHC correspond to an integrated luminosity of 12.9 inverse-femtobarns. No deviations are observed relative to the predictions of the standard model. The results are interpreted as exclusion limits on the dark matter production cross sections and parameters in models containing extra spatial dimensions. Improved limits are set with respect to previous searches using the monophoton final state. In particular, the limits on the extramore » dimension model parameters are the most stringent to date in this channel.« less

CO2 laser annealing of 50-microns-thick silicon solar cells

NASA Technical Reports Server (NTRS)

Walker, F. E.

1979-01-01

A test program is conducted to determine thin solar cell annealing effects using a laser energy source. A CO2 continuous-wave laser was used in annealing experiments on 50 micrometers-thick silicon solar cells after proton irradiation. Test cells were irradiated to a fluence of 1.0 x 10 to the 12th power protons/sq cm with 1.9 MeV protons. After irradiation, those cells receiving full proton dosage were degraded by an average of 30% in output power. In annealing tests laser beam exposure times on the solar cell varied from 2 seconds to 16 seconds reaching cell temperatures of from 400 C to 500 C. Under those conditions annealing test results showed recovery in cell output power of from 33% to 90%.

Search for new physics in the monophoton final state in proton-proton collisions at √{s}=13 TeV

NASA Astrophysics Data System (ADS)

Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Brandstetter, J.; Brondolin, E.; Dragicevic, M.; Erö, J.; Flechl, M.; Friedl, M.; Frühwirth, R.; Ghete, V. M.; Hartl, C.; Hörmann, N.; Hrubec, J.; Jeitler, M.; König, A.; Krätschmer, I.; Liko, D.; Matsushita, T.; Mikulec, I.; Rabady, D.; Rad, N.; Rahbaran, B.; Rohringer, H.; Schieck, J.; Strauss, J.; Waltenberger, W.; Wulz, C.-E.; Dvornikov, O.; Makarenko, V.; Mossolov, V.; Suarez Gonzalez, J.; Zykunov, V.; Shumeiko, N.; Alderweireldt, S.; De Wolf, E. A.; Janssen, X.; Lauwers, J.; Van De Klundert, M.; Van Haevermaet, H.; Van Mechelen, P.; Van Remortel, N.; Van Spilbeeck, A.; Abu Zeid, S.; Blekman, F.; D'Hondt, J.; Daci, N.; De Bruyn, I.; Deroover, K.; Lowette, S.; Moortgat, S.; Moreels, L.; Olbrechts, A.; Python, Q.; Skovpen, K.; Tavernier, S.; Van Doninck, W.; Van Mulders, P.; Van Parijs, I.; Brun, H.; Clerbaux, B.; De Lentdecker, G.; Delannoy, H.; Fasanella, G.; Favart, L.; Goldouzian, R.; Grebenyuk, A.; Karapostoli, G.; Lenzi, T.; Léonard, A.; Luetic, J.; Maerschalk, T.; Marinov, A.; Randle-conde, A.; Seva, T.; Vander Velde, C.; Vanlaer, P.; Vannerom, D.; Yonamine, R.; Zenoni, F.; Zhang, F.; Cornelis, T.; Dobur, D.; Fagot, A.; Gul, M.; Khvastunov, I.; Poyraz, D.; Salva, S.; Schöfbeck, R.; Tytgat, M.; Van Driessche, W.; Verbeke, W.; Zaganidis, N.; Bakhshiansohi, H.; Bondu, O.; Brochet, S.; Bruno, G.; Caudron, A.; De Visscher, S.; Delaere, C.; Delcourt, M.; Francois, B.; Giammanco, A.; Jafari, A.; Komm, M.; Krintiras, G.; Lemaitre, V.; Magitteri, A.; Mertens, A.; Musich, M.; Piotrzkowski, K.; Quertenmont, L.; Vidal Marono, M.; Wertz, S.; Beliy, N.; Aldá Júnior, W. L.; Alves, F. L.; Alves, G. A.; Brito, L.; Hensel, C.; Moraes, A.; Pol, M. E.; Rebello Teles, P.; Belchior Batista Das Chagas, E.; Carvalho, W.; Chinellato, J.; Custódio, A.; Da Costa, E. M.; Da Silveira, G. G.; De Jesus Damiao, D.; De Oliveira Martins, C.; Fonseca De Souza, S.; Huertas Guativa, L. M.; Malbouisson, H.; Matos Figueiredo, D.; Mora Herrera, C.; Mundim, L.; Nogima, H.; Prado Da Silva, W. L.; Santoro, A.; Sznajder, A.; Tonelli Manganote, E. J.; Torres Da Silva De Araujo, F.; Vilela Pereira, A.; Ahuja, S.; Bernardes, C. A.; Dogra, S.; Fernandez Perez Tomei, T. R.; Gregores, E. M.; Mercadante, P. G.; Moon, C. S.; Novaes, S. F.; Padula, Sandra S.; Romero Abad, D.; Ruiz Vargas, J. C.; Aleksandrov, A.; Hadjiiska, R.; Iaydjiev, P.; Rodozov, M.; Stoykova, S.; Sultanov, G.; Vutova, M.; Dimitrov, A.; Glushkov, I.; Litov, L.; Pavlov, B.; Petkov, P.; Fang, W.; Gao, X.; Ahmad, M.; Bian, J. G.; Chen, G. M.; Chen, H. S.; Chen, M.; Chen, Y.; Cheng, T.; Jiang, C. H.; Leggat, D.; Liu, Z.; Romeo, F.; Ruan, M.; Shaheen, S. M.; Spiezia, A.; Tao, J.; Wang, C.; Wang, Z.; Yazgan, E.; Zhang, H.; Zhao, J.; Ban, Y.; Chen, G.; Li, Q.; Liu, S.; Mao, Y.; Qian, S. J.; Wang, D.; Xu, Z.; Avila, C.; Cabrera, A.; Chaparro Sierra, L. F.; Florez, C.; Gomez, J. P.; González Hernández, C. F.; Ruiz Alvarez, J. D.; Sanabria, J. C.; Godinovic, N.; Lelas, D.; Puljak, I.; Ribeiro Cipriano, P. M.; Sculac, T.; Antunovic, Z.; Kovac, M.; Brigljevic, V.; Ferencek, D.; Kadija, K.; Mesic, B.; Susa, T.; Ather, M. W.; Attikis, A.; Mavromanolakis, G.; Mousa, J.; Nicolaou, C.; Ptochos, F.; Razis, P. A.; Rykaczewski, H.; Finger, M.; Finger, M.; Carrera Jarrin, E.; El-khateeb, E.; Elgammal, S.; Mohamed, A.; Kadastik, M.; Perrini, L.; Raidal, M.; Tiko, A.; Veelken, C.; Eerola, P.; Pekkanen, J.; Voutilainen, M.; Härkönen, J.; Järvinen, T.; Karimäki, V.; Kinnunen, R.; Lampén, T.; Lassila-Perini, K.; Lehti, S.; Lindén, T.; Luukka, P.; Tuominiemi, J.; Tuovinen, E.; Wendland, L.; Talvitie, J.; Tuuva, T.; Besancon, M.; Couderc, F.; Dejardin, M.; Denegri, D.; Fabbro, B.; Faure, J. L.; Favaro, C.; Ferri, F.; Ganjour, S.; Ghosh, S.; Givernaud, A.; Gras, P.; Hamel de Monchenault, G.; Jarry, P.; Kucher, I.; Locci, E.; Machet, M.; Malcles, J.; Rander, J.; Rosowsky, A.; Titov, M.; Abdulsalam, A.; Antropov, I.; Baffioni, S.; Beaudette, F.; Busson, P.; Cadamuro, L.; Chapon, E.; Charlot, C.; Davignon, O.; Granier de Cassagnac, R.; Jo, M.; Lisniak, S.; Lobanov, A.; Miné, P.; Nguyen, M.; Ochando, C.; Ortona, G.; Paganini, P.; Pigard, P.; Regnard, S.; Salerno, R.; Sirois, Y.; Stahl Leiton, A. G.; Strebler, T.; Yilmaz, Y.; Zabi, A.; Zghiche, A.; Agram, J.-L.; Andrea, J.; Bloch, D.; Brom, J.-M.; Buttignol, M.; Chabert, E. C.; Chanon, N.; Collard, C.; Conte, E.; Coubez, X.; Fontaine, J.-C.; Gelé, D.; Goerlach, U.; Le Bihan, A.-C.; Van Hove, P.; Gadrat, S.; Beauceron, S.; Bernet, C.; Boudoul, G.; Carrillo Montoya, C. A.; Chierici, R.; Contardo, D.; Courbon, B.; Depasse, P.; El Mamouni, H.; Fay, J.; Finco, L.; Gascon, S.; Gouzevitch, M.; Grenier, G.; Ille, B.; Lagarde, F.; Laktineh, I. B.; Lethuillier, M.; Mirabito, L.; Pequegnot, A. L.; Perries, S.; Popov, A.; Sordini, V.; Vander Donckt, M.; Verdier, P.; Viret, S.; Khvedelidze, A.; Tsamalaidze, Z.; Autermann, C.; Beranek, S.; Feld, L.; Kiesel, M. K.; Klein, K.; Lipinski, M.; Preuten, M.; Schomakers, C.; Schulz, J.; Verlage, T.; Albert, A.; Brodski, M.; Dietz-Laursonn, E.; Duchardt, D.; Endres, M.; Erdmann, M.; Erdweg, S.; Esch, T.; Fischer, R.; Güth, A.; Hamer, M.; Hebbeker, T.; Heidemann, C.; Hoepfner, K.; Knutzen, S.; Merschmeyer, M.; Meyer, A.; Millet, P.; Mukherjee, S.; Olschewski, M.; Padeken, K.; Pook, T.; Radziej, M.; Reithler, H.; Rieger, M.; Scheuch, F.; Sonnenschein, L.; Teyssier, D.; Thüer, S.; Cherepanov, V.; Flügge, G.; Kargoll, B.; Kress, T.; Künsken, A.; Lingemann, J.; Müller, T.; Nehrkorn, A.; Nowack, A.; Pistone, C.; Pooth, O.; Stahl, A.; Aldaya Martin, M.; Arndt, T.; Asawatangtrakuldee, C.; Beernaert, K.; Behnke, O.; Behrens, U.; Bin Anuar, A. A.; Borras, K.; Campbell, A.; Connor, P.; Contreras-Campana, C.; Costanza, F.; Diez Pardos, C.; Dolinska, G.; Eckerlin, G.; Eckstein, D.; Eichhorn, T.; Eren, E.; Gallo, E.; Garay Garcia, J.; Geiser, A.; Gizhko, A.; Grados Luyando, J. M.; Grohsjean, A.; Gunnellini, P.; Harb, A.; Hauk, J.; Hempel, M.; Jung, H.; Kalogeropoulos, A.; Karacheban, O.; Kasemann, M.; Keaveney, J.; Kleinwort, C.; Korol, I.; Krücker, D.; Lange, W.; Lelek, A.; Lenz, T.; Leonard, J.; Wissing, C.; Blobel, V.; Centis Vignali, M.; Draeger, A. R.; Dreyer, T.; Garutti, E.; Gonzalez, D.; Haller, J.; Hoffmann, M.; Junkes, A.; Klanner, R.; Kogler, R.; Kovalchuk, N.; Kurz, S.; Lapsien, T.; Marchesini, I.; Marconi, D.; Meyer, M.; Niedziela, M.; Nowatschin, D.; Pantaleo, F.; Peiffer, T.; Perieanu, A.; Scharf, C.; Schleper, P.; Schmidt, A.; Schumann, S.; Schwandt, J.; Sonneveld, J.; Stadie, H.; Steinbrück, G.; Stober, F. M.; Stöver, M.; Tholen, H.; Troendle, D.; Usai, E.; Vanelderen, L.; Vanhoefer, A.; Vormwald, B.; Akbiyik, M.; Barth, C.; Baur, S.; Baus, C.; Berger, J.; Butz, E.; Caspart, R.; Chwalek, T.; Colombo, F.; De Boer, W.; Dierlamm, A.; Fink, S.; Freund, B.; Friese, R.; Giffels, M.; Gilbert, A.; Goldenzweig, P.; Haitz, D.; Hartmann, F.; Heindl, S. M.; Husemann, U.; Kassel, F.; Katkov, I.; Kudella, S.; Mildner, H.; Mozer, M. U.; Müller, Th.; Plagge, M.; Quast, G.; Rabbertz, K.; Röcker, S.; Roscher, F.; Schröder, M.; Shvetsov, I.; Sieber, G.; Simonis, H. J.; Ulrich, R.; Wayand, S.; Weber, M.; Weiler, T.; Williamson, S.; Wöhrmann, C.; Wolf, R.; Anagnostou, G.; Daskalakis, G.; Geralis, T.; Giakoumopoulou, V. A.; Kyriakis, A.; Loukas, D.; Topsis-Giotis, I.; Kesisoglou, S.; Panagiotou, A.; Saoulidou, N.; Tziaferi, E.; Kousouris, K.; Evangelou, I.; Flouris, G.; Foudas, C.; Kokkas, P.; Loukas, N.; Manthos, N.; Papadopoulos, I.; Paradas, E.; Triantis, F. A.; Filipovic, N.; Pasztor, G.; Bencze, G.; Hajdu, C.; Horvath, D.; Sikler, F.; Veszpremi, V.; Vesztergombi, G.; Zsigmond, A. J.; Beni, N.; Czellar, S.; Karancsi, J.; Makovec, A.; Molnar, J.; Szillasi, Z.; Bartók, M.; Raics, P.; Trocsanyi, Z. L.; Ujvari, B.; Komaragiri, J. R.; Bahinipati, S.; Bhowmik, S.; Choudhury, S.; Mal, P.; Mandal, K.; Nayak, A.; Sahoo, D. K.; Sahoo, N.; Swain, S. K.; Bansal, S.; Beri, S. B.; Bhatnagar, V.; Bhawandeep, U.; Chawla, R.; Kalsi, A. K.; Kaur, A.; Kaur, M.; Kumar, R.; Kumari, P.; Mehta, A.; Mittal, M.; Singh, J. B.; Walia, G.; Kumar, Ashok; Bhardwaj, A.; Choudhary, B. C.; Garg, R. B.; Keshri, S.; Kumar, A.; Malhotra, S.; Naimuddin, M.; Ranjan, K.; Sharma, R.; Sharma, V.; Bhattacharya, R.; Bhattacharya, S.; Chatterjee, K.; Dey, S.; Dutt, S.; Dutta, S.; Ghosh, S.; Majumdar, N.; Modak, A.; Mondal, K.; Mukhopadhyay, S.; Nandan, S.; Purohit, A.; Roy, A.; Roy, D.; Roy Chowdhury, S.; Sarkar, S.; Sharan, M.; Thakur, S.; Behera, P. K.; Chudasama, R.; Dutta, D.; Jha, V.; Kumar, V.; Mohanty, A. K.; Netrakanti, P. K.; Pant, L. M.; Shukla, P.; Topkar, A.; Aziz, T.; Dugad, S.; Kole, G.; Mahakud, B.; Mitra, S.; Mohanty, G. B.; Parida, B.; Sur, N.; Sutar, B.; Banerjee, S.; Dewanjee, R. K.; Ganguly, S.; Guchait, M.; Jain, Sa.; Kumar, S.; Maity, M.; Majumder, G.; Mazumdar, K.; Sarkar, T.; Wickramage, N.; Chauhan, S.; Dube, S.; Hegde, V.; Kapoor, A.; Kothekar, K.; Pandey, S.; Rane, A.; Sharma, S.; Chenarani, S.; Eskandari Tadavani, E.; Etesami, S. M.; Khakzad, M.; Mohammadi Najafabadi, M.; Naseri, M.; Paktinat Mehdiabadi, S.; Rezaei Hosseinabadi, F.; Safarzadeh, B.; Zeinali, M.; Felcini, M.; Grunewald, M.; Abbrescia, M.; Calabria, C.; Caputo, C.; Colaleo, A.; Creanza, D.; Cristella, L.; De Filippis, N.; De Palma, M.; Fiore, L.; Iaselli, G.; Maggi, G.; Maggi, M.; Miniello, G.; My, S.; Nuzzo, S.; Pompili, A.; Pugliese, G.; Radogna, R.; Ranieri, A.; Selvaggi, G.; Sharma, A.; Silvestris, L.; Venditti, R.; Verwilligen, P.; Abbiendi, G.; Battilana, C.; Bonacorsi, D.; Braibant-Giacomelli, S.; Brigliadori, L.; Campanini, R.; Capiluppi, P.; Castro, A.; Cavallo, F. R.; Chhibra, S. S.; Codispoti, G.; Cuffiani, M.; Dallavalle, G. M.; Fabbri, F.; Fanfani, A.; Fasanella, D.; Giacomelli, P.; Grandi, C.; Guiducci, L.; Marcellini, S.; Masetti, G.; Montanari, A.; Navarria, F. L.; Perrotta, A.; Rossi, A. M.; Rovelli, T.; Siroli, G. P.; Tosi, N.; Albergo, S.; Costa, S.; Di Mattia, A.; Giordano, F.; Potenza, R.; Tricomi, A.; Tuve, C.; Barbagli, G.; Ciulli, V.; Civinini, C.; D'Alessandro, R.; Focardi, E.; Lenzi, P.; Meschini, M.; Paoletti, S.; Russo, L.; Sguazzoni, G.; Strom, D.; Viliani, L.; Benussi, L.; Bianco, S.; Fabbri, F.; Piccolo, D.; Primavera, F.; Calvelli, V.; Ferro, F.; Monge, M. R.; Robutti, E.; Tosi, S.; Brianza, L.; Brivio, F.; Ciriolo, V.; Dinardo, M. E.; Fiorendi, S.; Gennai, S.; Ghezzi, A.; Govoni, P.; Malberti, M.; Malvezzi, S.; Manzoni, R. A.; Menasce, D.; Moroni, L.; Paganoni, M.; Pedrini, D.; Pigazzini, S.; Ragazzi, S.; Tabarelli de Fatis, T.; Buontempo, S.; Cavallo, N.; De Nardo, G.; Di Guida, S.; Fabozzi, F.; Fienga, F.; Iorio, A. O. M.; Lista, L.; Meola, S.; Paolucci, P.; Sciacca, C.; Thyssen, F.; Azzi, P.; Bacchetta, N.; Benato, L.; Boletti, A.; Carlin, R.; Carvalho Antunes De Oliveira, A.; Checchia, P.; Dall'Osso, M.; De Castro Manzano, P.; Dorigo, T.; Dosselli, U.; Gasparini, U.; Lacaprara, S.; Margoni, M.; Meneguzzo, A. T.; Montecassiano, F.; Pazzini, J.; Pozzobon, N.; Ronchese, P.; Rossin, R.; Sgaravatto, M.; Simonetto, F.; Torassa, E.; Zanetti, M.; Zotto, P.; Zumerle, G.; Braghieri, A.; Fallavollita, F.; Magnani, A.; Montagna, P.; Ratti, S. P.; Re, V.; Ressegotti, M.; Riccardi, C.; Salvini, P.; Vai, I.; Vitulo, P.; Alunni Solestizi, L.; Bilei, G. M.; Ciangottini, D.; Fanò, L.; Lariccia, P.; Leonardi, R.; Mantovani, G.; Mariani, V.; Menichelli, M.; Saha, A.; Santocchia, A.; Androsov, K.; Azzurri, P.; Bagliesi, G.; Bernardini, J.; Boccali, T.; Castaldi, R.; Ciocci, M. A.; Dell'Orso, R.; Fedi, G.; Giassi, A.; Grippo, M. T.; Ligabue, F.; Lomtadze, T.; Martini, L.; Messineo, A.; Palla, F.; Rizzi, A.; Savoy-Navarro, A.; Spagnolo, P.; Tenchini, R.; Tonelli, G.; Venturi, A.; Verdini, P. G.; Barone, L.; Cavallari, F.; Cipriani, M.; Del Re, D.; Diemoz, M.; Gelli, S.; Longo, E.; Margaroli, F.; Marzocchi, B.; Meridiani, P.; Organtini, G.; Paramatti, R.; Preiato, F.; Rahatlou, S.; Rovelli, C.; Santanastasio, F.; Amapane, N.; Arcidiacono, R.; Argiro, S.; Arneodo, M.; Bartosik, N.; Bellan, R.; Biino, C.; Cartiglia, N.; Cenna, F.; Costa, M.; Covarelli, R.; Degano, A.; Demaria, N.; Kiani, B.; Mariotti, C.; Maselli, S.; Migliore, E.; Monaco, V.; Monteil, E.; Monteno, M.; Obertino, M. M.; Pacher, L.; Pastrone, N.; Pelliccioni, M.; Pinna Angioni, G. L.; Ravera, F.; Romero, A.; Ruspa, M.; Sacchi, R.; Shchelina, K.; Sola, V.; Solano, A.; Staiano, A.; Traczyk, P.; Belforte, S.; Casarsa, M.; Cossutti, F.; Della Ricca, G.; Zanetti, A.; Kim, D. H.; Kim, G. N.; Kim, M. S.; Lee, J.; Lee, S.; Lee, S. W.; Oh, Y. 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J.; Kellams, N.; Lannon, K.; Marinelli, N.; Meng, F.; Mueller, C.; Musienko, Y.; Planer, M.; Reinsvold, A.; Ruchti, R.; Rupprecht, N.; Smith, G.; Taroni, S.; Wayne, M.; Wolf, M.; Woodard, A.; Alimena, J.; Antonelli, L.; Bylsma, B.; Durkin, L. S.; Flowers, S.; Francis, B.; Hart, A.; Hill, C.; Ji, W.; Liu, B.; Luo, W.; Puigh, D.; Winer, B. L.; Wulsin, H. W.; Cooperstein, S.; Driga, O.; Elmer, P.; Hardenbrook, J.; Hebda, P.; Lange, D.; Luo, J.; Marlow, D.; Medvedeva, T.; Mei, K.; Ojalvo, I.; Olsen, J.; Palmer, C.; Piroué, P.; Stickland, D.; Svyatkovskiy, A.; Tully, C.; Malik, S.; Barker, A.; Barnes, V. E.; Folgueras, S.; Gutay, L.; Jha, M. K.; Jones, M.; Jung, A. W.; Khatiwada, A.; Miller, D. H.; Neumeister, N.; Schulte, J. F.; Sun, J.; Wang, F.; Xie, W.; Parashar, N.; Stupak, J.; Adair, A.; Akgun, B.; Chen, Z.; Ecklund, K. M.; Geurts, F. J. M.; Guilbaud, M.; Li, W.; Michlin, B.; Northup, M.; Padley, B. P.; Roberts, J.; Rorie, J.; Tu, Z.; Zabel, J.; Betchart, B.; Bodek, A.; de Barbaro, P.; Demina, R.; Duh, Y. t.; Ferbel, T.; Galanti, M.; Garcia-Bellido, A.; Han, J.; Hindrichs, O.; Khukhunaishvili, A.; Lo, K. H.; Tan, P.; Verzetti, M.; Agapitos, A.; Chou, J. P.; Gershtein, Y.; Gómez Espinosa, T. A.; Halkiadakis, E.; Heindl, M.; Hughes, E.; Kaplan, S.; Kunnawalkam Elayavalli, R.; Kyriacou, S.; Lath, A.; Montalvo, R.; Nash, K.; Osherson, M.; Saka, H.; Salur, S.; Schnetzer, S.; Sheffield, D.; Somalwar, S.; Stone, R.; Thomas, S.; Thomassen, P.; Walker, M.; Delannoy, A. G.; Foerster, M.; Heideman, J.; Riley, G.; Rose, K.; Spanier, S.; Thapa, K.; Bouhali, O.; Celik, A.; Dalchenko, M.; De Mattia, M.; Delgado, A.; Dildick, S.; Eusebi, R.; Gilmore, J.; Huang, T.; Juska, E.; Kamon, T.; Mueller, R.; Pakhotin, Y.; Patel, R.; Perloff, A.; Perniè, L.; Rathjens, D.; Safonov, A.; Tatarinov, A.; Ulmer, K. A.; Akchurin, N.; Damgov, J.; De Guio, F.; Dragoiu, C.; Dudero, P. R.; Faulkner, J.; Gurpinar, E.; Kunori, S.; Lamichhane, K.; Lee, S. W.; Libeiro, T.; Peltola, T.; Undleeb, S.; Volobouev, I.; Wang, Z.; Greene, S.; Gurrola, A.; Janjam, R.; Johns, W.; Maguire, C.; Melo, A.; Ni, H.; Sheldon, P.; Tuo, S.; Velkovska, J.; Xu, Q.; Arenton, M. W.; Barria, P.; Cox, B.; Hirosky, R.; Ledovskoy, A.; Li, H.; Neu, C.; Sinthuprasith, T.; Sun, X.; Wang, Y.; Wolfe, E.; Xia, F.; Clarke, C.; Harr, R.; Karchin, P. E.; Sturdy, J.; Zaleski, S.; Belknap, D. A.; Buchanan, J.; Caillol, C.; Dasu, S.; Dodd, L.; Duric, S.; Gomber, B.; Grothe, M.; Herndon, M.; Hervé, A.; Hussain, U.; Klabbers, P.; Lanaro, A.; Levine, A.; Long, K.; Loveless, R.; Pierro, G. A.; Polese, G.; Ruggles, T.; Savin, A.; Smith, N.; Smith, W. H.; Taylor, D.; Woods, N.

2017-10-01

A search is conducted for new physics in a final state containing a photon and missing transverse momentum in proton-proton collisions at √{s}=13 TeV. The data collected by the CMS experiment at the CERN LHC correspond to an integrated luminosity of 12.9 fb-1. No deviations are observed relative to the predictions of the standard model. The results are interpreted as exclusion limits on the dark matter production cross sections and parameters in models containing extra spatial dimensions. Improved limits are set with respect to previous searches using the monophoton final state. In particular, the limits on the extra dimension model parameters are the most stringent to date in this channel. [Figure not available: see fulltext.

Calibration and GEANT4 Simulations of the Phase II Proton Compute Tomography (pCT) Range Stack Detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Uzunyan, S. A.; Blazey, G.; Boi, S.

Northern Illinois University in collaboration with Fermi National Accelerator Laboratory (FNAL) and Delhi University has been designing and building a proton CT scanner for applications in proton treatment planning. The Phase II proton CT scanner consists of eight planes of tracking detectors with two X and two Y coordinate measurements both before and after the patient. In addition, a range stack detector consisting of a stack of thin scintillator tiles, arranged in twelve eight-tile frames, is used to determine the water equivalent path length (WEPL) of each track through the patient. The X-Y coordinates and WEPL are required input formore » image reconstruction software to find the relative (proton) stopping powers (RSP) value of each voxel in the patient and generate a corresponding 3D image. In this Note we describe tests conducted in 2015 at the proton beam at the Central DuPage Hospital in Warrenville, IL, focusing on the range stack calibration procedure and comparisons with the GEANT~4 range stack simulation.« less

Phosphorus-doped glass proton exchange membranes for low temperature direct methanol fuel cells

NASA Astrophysics Data System (ADS)

Prakash, Shruti; Mustain, William E.; Park, SeongHo; Kohl, Paul A.

Phosphorus-doped silicon dioxide thin films were used as ion exchange membranes in low temperature proton exchange membrane fuel cells. Phosphorus-doped silicon dioxide glass (PSG) was deposited via plasma-enhanced chemical vapor deposition (PECVD). The plasma deposition of PSG films allows for low temperature fabrication that is compatible with current microelectronic industrial processing. SiH 4, PH 3 and N 2O were used as the reactant gases. The effect of plasma deposition parameters, substrate temperature, RF power, and chamber pressure, on the ionic conductivity of the PSG films is elucidated. PSG conductivities as high as 2.54 × 10 -4 S cm -1 were realized, which is 250 times higher than the conductivity of pure SiO 2 films (1 × 10 -6 S cm -1) under identical deposition conditions. The higher conductivity films were deposited at low temperature, moderate pressure, limited reactant gas flow rate, and high RF power.

Triple-conducting layered perovskites as cathode materials for proton-conducting solid oxide fuel cells.

PubMed

Kim, Junyoung; Sengodan, Sivaprakash; Kwon, Goeun; Ding, Dong; Shin, Jeeyoung; Liu, Meilin; Kim, Guntae

2014-10-01

We report on an excellent anode-supported H(+) -SOFC material system using a triple conducting (H(+) /O(2-) /e(-) ) oxide (TCO) as a cathode material for H(+) -SOFCs. Generally, mixed ionic (O(2-) ) and electronic conductors (MIECs) have been selected as the cathode material of H(+) -SOFCs. In an H(+) -SOFC system, however, MIEC cathodes limit the electrochemically active sites to the interface between the proton conducting electrolyte and the cathode. New approaches to the tailoring of cathode materials for H(+) -SOFCs should therefore be considered. TCOs can effectively extend the electrochemically active sites from the interface between the cathode and the electrolyte to the entire surface of the cathode. The electrochemical performance of NBSCF/BZCYYb/BZCYYb-NiO shows excellent long term stability for 500 h at 1023 K with high power density of 1.61 W cm(-2) . © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Conductivity Analysis of Membranes for High-Temperature PEMFC Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reed, R.; Turner, J.A.

2005-01-01

Low-temperature operation requirements for per-fluorinated membranes are one factor that limits the viability of current fuel cell technology for transportation and other uses. Because of this, high-temperature membrane materials are being researched. The protonic conductivity of organic/inorganic hybrid composites, Nafion® analog material, and heteropoly acid doped Nafion membranes were studied using a BekkTech® conductivity test cell as a hydrogen pump. The goal was to find a high-temperature membrane with sufficient enough conductive properties to replace the currently implemented low-temperature membranes, such as Nafion. Four-point conductivity measurements were taken using a hydrogen pump experiment. Results showed that one of the organic/inorganicmore » membranes that we tested had similar protonic conductivity to Nafion. Nafion analog membranes were shown to have similar to slightly better conductivity than Nafion at high-temperatures. However, like Nafion, performance dropped upon dehydration of the membrane at higher temperatures. Of the heteropoly acid doped Nafion membranes studied, silicotungstic acid was found to be, overall, the most promising for use as a dopant.« less

Proton conducting membrane for fuel cells

DOEpatents

Colombo, Daniel G.; Krumpelt, Michael; Myers, Deborah J.; Kopasz, John P.

2005-12-20

An ion conducting membrane comprising dendrimeric polymers covalently linked into a network structure. The dendrimeric polymers have acid functional terminal groups and may be covalently linked via linking compounds, cross-coupling reactions, or copolymerization reactions. The ion conducting membranes may be produced by various methods and used in fuel cells.

Proton conducting membrane for fuel cells

DOEpatents

Colombo, Daniel G.; Krumpelt, Michael; Myers, Deborah J.; Kopasz, John P.

2007-03-27

An ion conducting membrane comprising dendrimeric polymers covalently linked into a network structure. The dendrimeric polymers have acid functional terminal groups and may be covalently linked via linking compounds, cross-coupling reactions, or copolymerization reactions. The ion conducting membranes may be produced by various methods and used in fuel cells.

Single-Event Effect Testing of the Vishay Si7414DN n-Type TrenchFET(Registered Trademark) Power MOSFET

NASA Technical Reports Server (NTRS)

Lauenstein, J.-M.; Casey, M. C.; Campola, M. A.; Phan, A. M.; Wilcox, E. P.; Topper, A. D.; Ladbury, R. L.

2017-01-01

This study was being undertaken to determine the single event effect susceptibility of the commercial Vishay 60-V TrenchFET power MOSFET. Heavy-ion testing was conducted at the Texas AM University Cyclotron Single Event Effects Test Facility (TAMU) and the Lawrence Berkeley National Laboratory BASE Cyclotron Facility (LBNL). In addition, initial 200-MeV proton testing was conducted at Massachusetts General Hospital (MGH) Francis H. Burr Proton Beam Therapy Center. Testing was performed to evaluate this device for single-event effects from lower-LET, lighter ions relevant to higher risk tolerant space missions.

Development and application of a water calorimeter for the absolute dosimetry of short-range particle beams.

PubMed

Renaud, J; Rossomme, S; Sarfehnia, A; Vynckier, S; Palmans, H; Kacperek, A; Seuntjens, J

2016-09-21

In this work, we describe a new design of water calorimeter built to measure absorbed dose in non-standard radiation fields with reference depths in the range of 6-20 mm, and its initial testing in clinical electron and proton beams. A functioning calorimeter prototype with a total water equivalent thickness of less than 30 mm was constructed in-house and used to obtain measurements in clinical accelerator-based 6 MeV and 8 MeV electron beams and cyclotron-based 60 MeV monoenergetic and modulated proton beams. Corrections for the conductive heat transfer due to dose gradients and non-water materials was also accounted for using a commercial finite element method software package. Absorbed dose to water was measured with an associated type A standard uncertainty of approximately 0.4% and 0.2% for the electron and proton beam experiments, respectively. In terms of thermal stability, drifts were on the order of a couple of hundred µK min -1 , with a short-term variation of 5-10 µK. Heat transfer correction factors ranged between 1.021 and 1.049. The overall combined standard uncertainty on the absorbed dose to water was estimated to be 0.6% for the 6 MeV and 8 MeV electron beams, as well as for the 60 MeV monoenergetic protons, and 0.7% for the modulated 60 MeV proton beam. This study establishes the feasibility of developing an absorbed dose transfer standard for short-range clinical electrons and protons and forms the basis for a transportable dose standard for direct calibration of ionization chambers in the user's beam. The largest contributions to the combined standard uncertainty were the positioning (⩽0.5%) and the correction due to conductive heat transfer (⩽0.4%). This is the first time that water calorimetry has been used in such a low energy proton beam.

Development and application of a water calorimeter for the absolute dosimetry of short-range particle beams

NASA Astrophysics Data System (ADS)

Renaud, J.; Rossomme, S.; Sarfehnia, A.; Vynckier, S.; Palmans, H.; Kacperek, A.; Seuntjens, J.

2016-09-01

In this work, we describe a new design of water calorimeter built to measure absorbed dose in non-standard radiation fields with reference depths in the range of 6-20 mm, and its initial testing in clinical electron and proton beams. A functioning calorimeter prototype with a total water equivalent thickness of less than 30 mm was constructed in-house and used to obtain measurements in clinical accelerator-based 6 MeV and 8 MeV electron beams and cyclotron-based 60 MeV monoenergetic and modulated proton beams. Corrections for the conductive heat transfer due to dose gradients and non-water materials was also accounted for using a commercial finite element method software package. Absorbed dose to water was measured with an associated type A standard uncertainty of approximately 0.4% and 0.2% for the electron and proton beam experiments, respectively. In terms of thermal stability, drifts were on the order of a couple of hundred µK min-1, with a short-term variation of 5-10 µK. Heat transfer correction factors ranged between 1.021 and 1.049. The overall combined standard uncertainty on the absorbed dose to water was estimated to be 0.6% for the 6 MeV and 8 MeV electron beams, as well as for the 60 MeV monoenergetic protons, and 0.7% for the modulated 60 MeV proton beam. This study establishes the feasibility of developing an absorbed dose transfer standard for short-range clinical electrons and protons and forms the basis for a transportable dose standard for direct calibration of ionization chambers in the user’s beam. The largest contributions to the combined standard uncertainty were the positioning (⩽0.5%) and the correction due to conductive heat transfer (⩽0.4%). This is the first time that water calorimetry has been used in such a low energy proton beam.

Graft-crosslinked copolymers based on poly(arylene ether ketone)-gc-sulfonated poly(arylene ether sulfone) for PEMFC applications.

PubMed

Zhang, Xuan; Hu, Zhaoxia; Luo, Linqiang; Chen, Shanshan; Liu, Jianmei; Chen, Shouwen; Wang, Lianjun

2011-07-15

Novel poly(arylene ether ketone) polymers with fluorophenyl pendants and phenoxide-terminated wholly sulfonated poly(arylene ether sulfone) oligomers are prepared via Ni(0)-catalyzed and nucleophilic polymerization, respectively, and subsequently used as starting materials to obtain graft-crosslinked membranes as polymer electrolyte membranes. The phenoxide-terminated sulfonated moieties are introduced as hydrophilic parts as well as crosslinking units. The chemical structure and morphology of the obtained membranes are confirmed by (1) H NMR and tapping-mode AFM. The properties required for fuel cell applications, including water uptake and dimensional change, as well as proton conductivity, are investigated. AFM results show a clear nanoscale phase-separation microstructure of the obtained membranes. The membranes show good dimensional stability and reasonably high proton conductivities under 30-90% relative humidity. The anisotropic proton conductivity ratios (σ(formula see text) ) of the membranes in water are in the range 0.65-0.92, and increase with an increase in hydrophilic block length. The results indicate that the graft-crosslinked membranes are promising candidates for applications as polymer electrolyte membranes. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enhanced Proton Conductivity and Methanol Permeability Reduction via Sodium Alginate Electrolyte-Sulfonated Graphene Oxide Bio-membrane

NASA Astrophysics Data System (ADS)

Shaari, N.; Kamarudin, S. K.; Basri, S.; Shyuan, L. K.; Masdar, M. S.; Nordin, D.

2018-03-01

The high methanol crossover and high cost of Nafion® membrane are the major challenges for direct methanol fuel cell application. With the aim of solving these problems, a non-Nafion polymer electrolyte membrane with low methanol permeability and high proton conductivity based on the sodium alginate (SA) polymer as the matrix and sulfonated graphene oxide (SGO) as an inorganic filler (0.02-0.2 wt%) was prepared by a simple solution casting technique. The strong electrostatic attraction between -SO3H of SGO and the sodium alginate polymer increased the mechanical stability, optimized the water absorption and thus inhibited the methanol crossover in the membrane. The optimum properties and performances were presented by the SA/SGO membrane with a loading of 0.2 wt% SGO, which gave a proton conductivity of 13.2 × 10-3 Scm-1, and the methanol permeability was 1.535 × 10-7 cm2 s-1 at 25 °C, far below that of Nafion (25.1 × 10-7 cm2 s-1) at 25 °C. The mechanical properties of the sodium alginate polymer in terms of tensile strength and elongation at break were improved by the addition of SGO.

Biomedical effects of protons with different levels of LET

NASA Astrophysics Data System (ADS)

Bulinina, Taisia; Vorozhtsova, Svetlana; Abrosimova, Alla; Ivanov, Alexander; Molokanov, Alexander

Protons compose 80% of space radiation, thus, if the average energy of protons is 45 MeV, then there is a proton range much differing on the LET level available. In this regard, the study of protons radiobiological effects with different levels of LET is relevant. On the basis of the JINR Phasotron we designed the special device allowing to irradiate experimental animals - mice at the various regions of proton beam differing more than 3 times on the level of LET. The experiments were carried out on outbred CD-1 females mice and C57Bl6 males. Animals were irradiated at two points of the depth dose distribution - at the entrance of the proton beam and at the modified Bragg peak, extended with a ridge filter. Total irradiation of mice was conducted by a proton beam with energy of 171 MeV at doses of 1.0, 2.5 and 5.0 Gy at the JINR Phasotron beam, is used for the treatment of patients. LET of 171 MeV protons was 0.49 keV/mkm, the dose rate was 0.37 Gy/min. Range of energy at the modified Bragg peak is 0-30 MeV. Dose rate was 0.8 Gy/min. Average value of LET at the modified Bragg peak was 1.6 keV/mkm. In the modified Bragg peak the contribution to the absorbed dose of protons with low-LET radiation was about 67%, with LET 25-50 keV/mkm was 23% and with high -LET (50-100 keV/mkm) was 10%. For comparison irradiation of 60Co γ-rays was conducted on the device for remote radiation therapy Rokus-M MTC JINR in the same doses. The average dose of (60) Co gammaγ-rays with LET of 0.3 keV/mkm was 1 Gy/min. The experiments showed that after 24 hours of both proton irradiation with a high level of LET, and with 171 MeV proton beam in the object, a clear dose-dependent loss of bone marrow hematopoiesis is observed, the depth of destruction after irradiation by protons with a high level of increased from 1.14 to 1.36 with increasing doses of irradiation from 1.0 to 5.0 Gy. Restoration of bone marrow cellularity by the 8th day after exposure also was reduced in mice irradiated by protons with a high level of LET. After irradiation at a dose of 5.0 Gy with a high level of LET we noted deeper defeat of the cytogenetic apparatus of bone marrow cells and slow elimination of chromosomal aberrations in comparison with protons at the entrance of the object and gammaγ-rays (60) Co. The distinction in the defeat and the restoration of the number of white blood cells in the peripheral blood, thymus and spleen had a more complicated character. The obtained results showed that the striking effects of protons with a high level of LET radiation are significantly higher in comparison with other groups: mice irradiated by protons with LET 0.49 keV/mkm and gammaγ-rays (60) Co with LET 0.3 keV/mkm.

Top-down control analysis of the cadmium effects on molluscan mitochondria and the mechanisms of cadmium-induced mitochondrial dysfunction.

PubMed

Kurochkin, Ilya O; Etzkorn, Markus; Buchwalter, David; Leamy, Larry; Sokolova, Inna M

2011-01-01

Cadmium (Cd) is a toxic metal and an important environmental pollutant that can strongly affect mitochondrial function and bioenergetics in animals. We investigated the mechanisms of Cd action on mitochondrial function of a marine mollusk (the eastern oyster Crassostrea virginica) by performing a top-down control analysis of the three major mitochondrial subsystems (substrate oxidation, proton leak, and phosphorylation). Our results showed that the substrate oxidation and proton leak subsystems are the main targets for Cd toxicity in oyster mitochondria. Exposure to 12.5 μM Cd strongly inhibited the substrate oxidation subsystem and stimulated the proton conductance across the inner mitochondrial membrane. Proton conductance was also elevated and substrate oxidation inhibited by Cd in the presence of a mitochondrially targeted antioxidant, MitoVitE, indicating that Cd effects on these subsystems were to a large extent ROS independent. Cd did not affect the kinetics of the phosphorylation system, indicating that it has negligible effects on F₁, F(O) ATP synthase and/or the adenine nucleotide transporter in oyster mitochondria. Cd exposure altered the patterns of control over mitochondrial respiration, increasing the degree of control conferred by the substrate oxidation subsystem, especially in resting (state 4) mitochondria. Taken together, these data suggest that Cd-induced decrease of mitochondrial efficiency and ATP production are predominantly driven by the high sensitivity of substrate oxidation and proton leak subsystems to this metal.

Strongly coupled Sm0.2Ce0.8O2-Na2CO3 nanocomposite for low temperature solid oxide fuel cells: One-step synthesis and super interfacial proton conduction

NASA Astrophysics Data System (ADS)

Zhang, Guanghong; Li, Wenjian; Huang, Wen; Cao, Zhiqun; Shao, Kang; Li, Fengjiao; Tang, Chaoyun; Li, Cuihua; He, Chuanxin; Zhang, Qianling; Fan, Liangdong

2018-05-01

Highly conductive ceria-carbonate composite represents one type of most promising electrolyte materials for low temperature solid oxide fuel cells (SOFCs). Composites with large oxide-carbonate interface and homogeneous element/phase distribution are desirable to further enhance electrical properties and to study the ionic conduction mechanism. In this work, we report the successful synthesis of element/phase well-distributed, interfacial strongly coupled Sm0.2Ce0.8O2-Na2CO3 (NSDC) nanocomposite with different residual carbonate contents by an in-situ one-pot one-step citric acid-nitrate combustion method. Interestingly, NSDC shows distinct properties over those prepared by conventional methods and improved ionic conductivity. In particular, NSDC9010 nanocomposite displays a proton conductivity of 0.044 S cm-1 at 650 °C, which is 3-5 times higher than the oxide proton conductors. Electrolyte supported SOFCs based on the resultant nanocomposite electrolyte, NSDC9010, give the best power output of 281.5 mW cm-2 at 600 °C with LiNiO2 symmetric electro-catalysts. The excellent ionic conductivity and fuel cell performance are correlated with the unique core-shell structure, good phase distribution and large interfacial area induced by the one-step fabrication method, the strong coupling between oxide and carbonate as verified by the differential thermal and Raman spectroscopy characterization results and the optimal interfacial carbonate layer thickness by intentionally adjusting of carbonate contents.

Single-layer nanosheets with exceptionally high and anisotropic hydroxyl ion conductivity

PubMed Central

Sun, Pengzhan; Ma, Renzhi; Bai, Xueyin; Wang, Kunlin; Zhu, Hongwei; Sasaki, Takayoshi

2017-01-01

When the dimensionality of layered materials is reduced to the physical limit, an ultimate two-dimensional (2D) anisotropy and/or confinement effect may bring about extraordinary physical and chemical properties. Layered double hydroxides (LDHs), bearing abundant hydroxyl groups covalently bonded within 2D host layers, have been proposed as inorganic anion conductors. However, typical hydroxyl ion conductivities for bulk or lamellar LDHs, generally up to 10−3 S cm−1, are considered not high enough for practical applications. We show that single-layer LDH nanosheets exhibited exceptionally high in-plane conductivities approaching 10−1 S cm−1, which were the highest among anion conductors and comparable to proton conductivities in commercial proton exchange membranes (for example, Nafion). The in-plane conductivities were four to five orders of magnitude higher than the cross-plane or cross-membrane values of restacked LDH nanosheets. This 2D superionic transport characteristic might have great promises in a variety of applications including alkaline fuel cells and water electrolysis. PMID:28439551

Nanoscale current imaging of the conducting channels in proton exchange membrane fuel cells.

PubMed

Bussian, David A; O'Dea, James R; Metiu, Horia; Buratto, Steven K

2007-02-01

The electrochemically active area of a proton exchange membrane fuel cell (PEMFC) is investigated using conductive probe atomic force microscopy (CP-AFM). A platinum-coated AFM tip is used as a nanoscale cathode in an operating PEMFC. We present results that show highly inhomogeneous distributions of conductive surface domains at several length scales. At length scales on the order of the aqueous domains of the membrane, approximately 50 nm, we observe single channel electrochemistry. I-V curves for single conducting channels are obtained, which yield insight into the nature of conductive regions across the PEM. In addition, we demonstrate a new characterization technique, phase current correlation microscopy, which gives a direct measure of the electrochemical activity for each aqueous domain. This shows that a large number ( approximately 60%) of the aqueous domains present at the surface of an operating Nafion membrane are inactive. We attribute this to a combination of limited aqueous domain connectivity and catalyst accessibility.

First Principles Study for Proton Transport and Diffusion Behavior in Hydrous Hexagonal WO3

NASA Astrophysics Data System (ADS)

Liu, Chi-Ping; Zhou, Fei; Ozolins, Vidvuds; QPAM Team

2013-03-01

Proton transport is of great importance in biological species and energy storage and conversion systems. Previous studies have shown fast proton conduction in liquids and polymers but seldom in inorganic materials. In this work, first principles density functional theory (DFT) reveals that the formation of hydronium and water chains inside the hexagonal channels plays the key roles for the anomalously fast proton transport, by following modified Grotthuss mechanism. Our DFT study shows the detailed microscopic proton diffusion mechanism along the channel in hydrous WO3 with 50% water composition, which is proper for water chain formation. The water chain in the channel serves as a possible diffusion media for hydronium (H3O +) . With the continuous formation and cleavage of hydrogen bonds in the channel, the hydronium diffuses by hydrogen bonds exchange between water molecules. This mechanism is very similar with Grotthuss relay mechanism for proton transport in liquid. The possible proton diffusion were studied for hydronium is either far away from the water chain bond defect or next to H2O defect at the end of water chain. The diffusion barriers for both conditions are around 150 meV to 200 meV, and water defects reorganization in the chain is the rate-limited step for proton diffusion. These small diffusion barriers could explain the fast 1-D proton transport in hydrous WO3 channel. Further studies about fast proton transport in other inorganic materials could be an important topic in not only biochemistry but also clean energy applications like fuel cell applications.

[Initial experience of proton beam therapy at the new facility of the University of Tsukuba].

PubMed

Kagei, Kenji; Tokuuye, Koichi; Sugahara, Shinji; Hata, Masaharu; Igaki, Hiroshi; Hashimoto, Takayuki; Ohara, Kiyoshi; Akine, Yasuyuki

2004-05-01

To present the initial experience with proton beam therapy at the new Proton Medical Research Center (PMRC) of the University of Tsukuba. The new facility has a synchrotron with maximum energy of 250MeV and two rotational gantries. We treated 105 patients with 120 lesions with proton beams in the first year, beginning in September 2001. The most common lesion treated was primary liver cancer (40 lesions) followed by lung cancer, head and neck cancers, and prostate cancer. Concurrent X-ray radiotherapy was given for 38 of the 120 lesions. The median follow-up period was 11 months (range, 1-19 months). Of the 105 patients, 97% had Grade 0-2 RTOG/EORTC acute morbidities, while the remaining 3% had Grade 3. Tumor response after irradiation was CR for 35% of the lesions, PR for 25%, SD for 22%, PD for 9%, and not evaluated for 9%. The proton beam therapy conducted at the new facility of the University of Tsukuba was safe and effective.

Understanding proton-conducting perovskite interfaces using atom probe tomography

NASA Astrophysics Data System (ADS)

Clark, Daniel R.

Proton-conducting ceramics are under intense scientific investigation for a number of exciting applications, including fuel cells, electrolyzers, hydrogen separation membranes, membrane reactors, and sensors. However, commercial application requires deeper understanding and improvement of proton conductivity in these materials. It is well-known that proton conductivity in these materials is often limited by highly resistive grain boundaries (GBs). While these conductivity-limiting GBs are still not well understood, it is hypothesized that their blocking nature stems from the formation of a positive (proton-repelling) space-charge zone. Furthermore, it has been observed that the strength of the blocking behavior can change dramatically depending on the fabrication process used to make the ceramic. This thesis applies laser-assisted atom probe tomography (LAAPT) to provide new insights into the GB chemistry and resulting space-charge behavior of BaZr0.9Y0.1O 3--delta (BZY10), a prototypical proton-conducting ceramic. LAAPT is an exciting characterization technique that allows for three-dimensional nm-scale spatial resolution and very high chemical resolution (up to parts-per-million). While it is challenging to quantitatively apply LAAPT to complex, multi-cation oxide materials, this thesis successfully develops a method to accurately quantify the stoichiometry of BZY10 and maintain minimal quantitative cationic deviation at a laser energies of approximately 10--20 pJ. With the analysis technique specifically optimized for BZY10, GB chemistry is then examined for BZY10 samples prepared using four differing processing methods: (1) spark plasma sintering (SPS), (2) conventional sintering using powder prepared by solid-state reaction followed by high-temperature annealing (HT), (3) conventional sintering using powder prepared by solid-state reaction with NiO used as a sintering aid (SSR-Ni), and (4) solid-state reactive sintering directly from BaCO3, ZrO2, and Y2O3 precursor powders with 1 wt. % NiO as a reactive sintering aid (SSRS-Ni). It is observed that oxygen depletion (oxygen-vacancy accumulation) occurs at all GBs. Segregation of the constituent cations, Ba, Zr, and Y, is found to be variable across all samples although zirconium depletion and yttrium accumulation are most prevalent. Additionally, impurities such as Al, Fe, Mg, Ni, Si, and Sr are shown to generally accumulate at the GBs. Finally, LAAPT-derived GB chemistry data is combined with electrostatic modeling to examine the electronic structure of a BZY10 GB, revealing significant non-uniformity in the space charge region at the GB with an average space-charge potential of approximately 580 mV, extending 5--7 nm in width from the GB core. This result demonstrates how LAAPT can not only be used to further understand the role of GB chemistry within oxide materials, but can also be used to examine the electronic structure, allowing for the possibility of engineering these interfaces to improve their electrochemical performance.

Influence of aminosilane precursor concentration on physicochemical properties of composite Nafion membranes for vanadium redox flow battery applications

NASA Astrophysics Data System (ADS)

Kondratenko, Mikhail S.; Karpushkin, Evgeny A.; Gvozdik, Nataliya A.; Gallyamov, Marat O.; Stevenson, Keith J.; Sergeyev, Vladimir G.

2017-02-01

A series of composite proton-exchange membranes have been prepared via sol-gel modification of commercial Nafion membranes with [N-(2-aminoethyl)-3-aminopropyl]trimethoxysilane. The structure and physico-chemical properties (water uptake, ion-exchange capacity, vanadyl ion permeability, and proton conductivity) of the prepared composite membranes have been studied as a function of the precursor loading (degree of the membrane modification). If the amount of the precursor is below 0.4/1 M ratio of the amino groups of the precursor to the sulfonic groups of Nafion, the composite membranes exhibit decreased vanadium ion permeability while having relatively high proton conductivity. With respect to the use of a non-modified Nafion membrane, the performance of the composite membrane with an optimum precursor loading in a single-cell vanadium redox flow battery demonstrates enhanced energy efficiency in 20-80 mA cm-2 current density range. The maximum efficiency increase of 8% is observed at low current densities.

[Effects of exogenous spermidine on lipid peroxidation and membrane proton pump activity of cucumber seedling leaves under high temperature stress].

PubMed

Tian, Jing; Guo, Shi-Rong; Sun, Jin; Wang, Li-Ping; Yang, Yan-Juan; Li, Bin

2011-12-01

Taking a relatively heat-resistant cucumber (Cucumis sativus) cultivar 'Jinchun No. 4' as test material, a sand culture experiment was conducted in growth chamber to investigate the effects of foliar spraying spermidine (Spd) on the lipid peroxidation, membrane proton pump activity, and corresponding gene expression of cucumber seedling leaves under high temperature stress. Compared with the control, foliar spraying Spd increased the plant height, stem diameter, dry and fresh mass, and leaf area significantly, and inhibited the increase of leaf relative conductivity, malondialdehyde (MDA) content, and lipoxygenase (LOX) activity effectively. Foliar spraying Spd also helped to the increase of leaf plasma membrane- and tonoplast H(+)-ATPase activity, but no significant difference was observed in the gene expression levels. These results suggested that exogenous Spd could significantly decrease the leaf lipid peroxidation and increase the proton pump activity, and thus, stabilize the leaf membrane structure and function, alleviate the damage induced by high temperature stress, and enhance the heat tolerance of cucumber seedlings.

Mechanism of aquaporin-4's fast and highly selective water conduction and proton exclusion.

PubMed

Tani, Kazutoshi; Mitsuma, Tadanori; Hiroaki, Yoko; Kamegawa, Akiko; Nishikawa, Kouki; Tanimura, Yukihiro; Fujiyoshi, Yoshinori

2009-06-19

Members of the aquaporin (AQP) family are expressed in almost every organism, including 13 homologues in humans. Based on the electron crystallographic structure of AQP1, the hydrogen-bond isolation mechanism was proposed to explain why AQPs are impermeable to protons despite their very fast water conduction. The mechanism by which AQPs exclude protons remained controversial, however. Here we present the structure of AQP4 at 2.8 A resolution obtained by electron crystallography of double-layered two-dimensional crystals. The resolution has been improved from the previous 3.2 A, with accompanying improvement in data quality resulting in the ability to identify individual water molecules. Our structure of AQP4, the predominant water channel in the brain, reveals eight water molecules in the channel. The arrangement of the waters provides support for the hydrogen-bond isolation mechanism. Our AQP4 structure also visualizes five lipids, showing that direct interactions of the extracellular surface of AQP4 with three lipids in the adjoining membrane help stabilize the membrane junction.

A parameter study of the two-fluid solar wind

NASA Technical Reports Server (NTRS)

Sandbaek, Ornulf; Leer, Egil; Holzer, Thomas E.

1992-01-01

A two-fluid model of the solar wind was introduced by Sturrock and Hartle (1966) and Hartle and Sturrock (1968). In these studies the proton energy equation was integrated neglecting the heat conductive term. Later several authors solved the equations for the two-fluid solar wind model keeping the proton heat conductive term. Methods where the equations are integrated simultaneously outward and inward from the critical point were used. The equations were also integrated inward from a large heliocentric distance. These methods have been applied to cases with low coronal base electron densities and high base temperatures. In this paper we present a method of integrating the two-fluid solar wind equations using an iteration procedure where the equations are integrated separately and the proton flux is kept constant during the integrations. The technique is applicable for a wide range of coronal base densities and temperatures. The method is used to carry out a parameter study of the two-fluid solar wind.

A novel layered perovskite cathode for proton conducting solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Ding, Hanping; Xue, Xingjian; Liu, Xingqin; Meng, Guangyao

BaZr 0.1Ce 0.7Y 0.2O 3- δ (BZCY7) exhibits adequate proton conductivity as well as sufficient chemical and thermal stability over a wide range of SOFC operating conditions, while layered SmBa 0.5Sr 0.5Co 2O 5+ δ (SBSC) perovskite demonstrates advanced electrochemical properties based on doped ceria electrolyte. This research fully takes advantage of these advanced properties and develops novel protonic ceramic membrane fuel cells (PCMFCs) of Ni-BZCY7|BZCY7|SBSC. The results show that the open-circuit potential of 1.015 V and maximum power density of 533 mW cm -2 are achieved at 700 °C. With temperature increase, the total cell resistance decreases, among which electrolyte resistance becomes increasingly dominant over polarization resistance. The results also indicate that SBSC perovskite cathode is a good candidate for intermediate temperature PCMFC development, while the developed Ni-BZCY7|BZCY7|SBSC cell is a promising functional material system for next generation SOFCs.

Enhancement of the ionic conductivity of olivine by the water incorporation based on the Mg diffusivity

NASA Astrophysics Data System (ADS)

Katsura, T.; Fei, H.; Koizumi, S.; Sakamoto, N.; Yurimoto, H.

2016-12-01

Although the water corporation has been considered to enhance the electrical conductivity of olivine by the proton conduction, the magnitude of the proton conduction is relatively small at asthenospheric temperatures because of its smaller activation energy than those of the small polaron and ionic conductions. However, the water incorporation could enhance the ionic conduction, because it should increase the defect density in the Mg sites. Since the ionic conductivity is proportional to the diffusivity, we have measured the self-diffusion coefficients of Mg in forsterite as a function of pressure, temperature and water content. We annealed fine-grained polycrystalline aggregates of forsterite with water contents up to 300 ppm, on whose polished plane a 25Mg-enriched Mg2SiO4 thin film was made, at pressures of 1 to 13 GPa and temperatures of 1100 to 1300 K. The lattice and grain-boundary diffusion coefficients were calculated simultaneously using profiles obtained by the depth analysis of SIMS. Experimental results gave the activation energy of 280 ± 30 and 360 ± 30 kJ/mol, activation volumes of 4.3 ± 0.3 and 3.9 ± 0.7 cm3/mol, and water content exponents of 1.2 ± 0.2 and 1.0 ± 0.1 for the lattice and grain-boundary diffusions, respectively. Using the ionic conduction data by Constable [2006] and Yoshino et al. [2009], and the water and pressure effects on Mg diffusivity in this study, the ionic conduction is found by 2 orders of magnitude higher than the small polaron and proton conductions under oceanic-asthenosphere conditions. Thus, the high conductivity of the oceanic asthenosphere will be governed by the water-enhanced ionic conduction. The negative pressure dependence of the Mg diffusivity and the gradual temperature increase in the asthenosphere will produce a conductivity maximum at the top of the asthenosphere. The high-conductivity layer at the top of the asthenosphere observed under very young oceanic plates can be attributed to this ionic conduction maximum.

MO-FG-CAMPUS-JeP1-03: Luminescence Imaging of Water During Proton Beam Irradiation for Range Estimation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamamoto, S; Komori, M; Toshito, T

Purpose: Since proton therapy has the ability to selectively deliver a dose to a target tumor, the dose distribution should be accurately measured. A precise and efficient method to evaluate the dose distribution is desired. We found that luminescence was emitted from water during proton irradiation and thought this phenomenon could be used for estimating the dose distribution. Methods: For this purpose, we placed water phantoms set on a table with a spot-scanning proton-therapy system, and luminescence images of these phantoms were measured with a high-sensitivity cooled charge coupled device (CCD) camera during proton-beam irradiation. We also conducted the imagingmore » of phantoms of pure-water, fluorescein solution and acrylic block. We made three dimensional images from the projection data. Results: The luminescence images of water phantoms during the proton-beam irradiations showed clear Bragg peaks, and the measured proton ranges from the images were almost the same as those obtained with an ionization chamber. The image of the pure-water phantom also showed almost the same distribution as the tap-water phantom, indicating that the luminescence image was not related to impurities in the water. The luminescence image of fluorescein solution had ∼3 times higher intensity than water, with the same proton range as that of water. The luminescence image of the acrylic phantom had 14.5% shorter proton range than that of water; the proton range in the acrylic phantom was relatively matched with the calculated value. The luminescence images of the tap-water phantom during proton irradiation could be obtained in less than 2 sec. Three dimensional images were successfully obtained which have more quantitative information. Conclusion: Luminescence imaging during proton-beam irradiation has the potential to be a new method for range estimations in proton therapy.« less

The Mg2+-containing Water Cluster of Mammalian Cytochrome c Oxidase Collects Four Pumping Proton Equivalents in Each Catalytic Cycle*

PubMed Central

Yano, Naomine; Muramoto, Kazumasa; Shimada, Atsuhiro; Takemura, Shuhei; Baba, Junpei; Fujisawa, Hidenori; Mochizuki, Masao; Shinzawa-Itoh, Kyoko; Yamashita, Eiki; Tsukihara, Tomitake; Yoshikawa, Shinya

2016-01-01

Bovine heart cytochrome c oxidase (CcO) pumps four proton equivalents per catalytic cycle through the H-pathway, a proton-conducting pathway, which includes a hydrogen bond network and a water channel operating in tandem. Protons are transferred by H3O+ through the water channel from the N-side into the hydrogen bond network, where they are pumped to the P-side by electrostatic repulsion between protons and net positive charges created at heme a as a result of electron donation to O2 bound to heme a3. To block backward proton movement, the water channel remains closed after O2 binding until the sequential four-proton pumping process is complete. Thus, the hydrogen bond network must collect four proton equivalents before O2 binding. However, a region with the capacity to accept four proton equivalents was not discernable in the x-ray structures of the hydrogen bond network. The present x-ray structures of oxidized/reduced bovine CcO are improved from 1.8/1.9 to 1.5/1.6 Å resolution, increasing the structural information by 1.7/1.6 times and revealing that a large water cluster, which includes a Mg2+ ion, is linked to the H-pathway. The cluster contains enough proton acceptor groups to retain four proton equivalents. The redox-coupled x-ray structural changes in Glu198, which bridges the Mg2+ and CuA (the initial electron acceptor from cytochrome c) sites, suggest that the CuA-Glu198-Mg2+ system drives redox-coupled transfer of protons pooled in the water cluster to the H-pathway. Thus, these x-ray structures indicate that the Mg2+-containing water cluster is the crucial structural element providing the effective proton pumping in bovine CcO. PMID:27605664

The Mg2+-containing Water Cluster of Mammalian Cytochrome c Oxidase Collects Four Pumping Proton Equivalents in Each Catalytic Cycle.

PubMed

Yano, Naomine; Muramoto, Kazumasa; Shimada, Atsuhiro; Takemura, Shuhei; Baba, Junpei; Fujisawa, Hidenori; Mochizuki, Masao; Shinzawa-Itoh, Kyoko; Yamashita, Eiki; Tsukihara, Tomitake; Yoshikawa, Shinya

2016-11-11

Bovine heart cytochrome c oxidase (CcO) pumps four proton equivalents per catalytic cycle through the H-pathway, a proton-conducting pathway, which includes a hydrogen bond network and a water channel operating in tandem. Protons are transferred by H 3 O + through the water channel from the N-side into the hydrogen bond network, where they are pumped to the P-side by electrostatic repulsion between protons and net positive charges created at heme a as a result of electron donation to O 2 bound to heme a 3 To block backward proton movement, the water channel remains closed after O 2 binding until the sequential four-proton pumping process is complete. Thus, the hydrogen bond network must collect four proton equivalents before O 2 binding. However, a region with the capacity to accept four proton equivalents was not discernable in the x-ray structures of the hydrogen bond network. The present x-ray structures of oxidized/reduced bovine CcO are improved from 1.8/1.9 to 1.5/1.6 Å resolution, increasing the structural information by 1.7/1.6 times and revealing that a large water cluster, which includes a Mg 2+ ion, is linked to the H-pathway. The cluster contains enough proton acceptor groups to retain four proton equivalents. The redox-coupled x-ray structural changes in Glu 198 , which bridges the Mg 2+ and Cu A (the initial electron acceptor from cytochrome c) sites, suggest that the Cu A -Glu 198 -Mg 2+ system drives redox-coupled transfer of protons pooled in the water cluster to the H-pathway. Thus, these x-ray structures indicate that the Mg 2+ -containing water cluster is the crucial structural element providing the effective proton pumping in bovine CcO. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Structural diversity in multinuclear Pd(II) assemblies that show low-humidity proton conduction.

PubMed

Samanta, Dipak; Mukherjee, Partha Sarathi

2014-05-05

Systematic investigation on synergetic effects of geometry, length, denticity, and asymmetry of donors was performed through the formation of a series of uncommon Pd(II) aggregates by employing the donor in a multicomponent self-assembly of a cis-blocked 90° Pd(II) acceptor and a tetratopic donor. Some of these assemblies represent the first examples of these types of structures, and their formation is not anticipated by only taking the geometry of the donor and the acceptor building units into account. Analysis of the crystal packing of the X-ray structure revealed several H bonds between the counteranions (NO3 (-) ) and water molecules (OH⋅⋅⋅ON). Moreover, H-bonded 3D-networks of water are present in the molecular pockets, which show water-adsorption properties with some variation in water affinity. Interestingly, these complexes exhibit proton conductivity (1.87×10(-5) -6.52×10(-4)  Scm(-1) ) at 296 K and low relative humidity (ca. 46 %) with activation energies of 0.29-0.46 eV. Moreover, the conductivities further increase with the enhancement of humidity. The ability of these assemblies to exhibit proton-conducting properties under low-humidity conditions makes these materials highly appealing as electrolytes in batteries and in fuel-cell applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A macroscopic model of proton transport through the membrane-ionomer interface of a polymer electrolyte membrane fuel cell.

PubMed

Kumar, Milan; Edwards, Brian J; Paddison, Stephen J

2013-02-14

The membrane-ionomer interface is the critical interlink of the electrodes and catalyst to the polymer electrolyte membrane (PEM); together forming the membrane electrode assembly in current state-of-the-art PEM fuel cells. In this paper, proton conduction through the interface is investigated to understand its effect on the performance of a PEM fuel cell. The water containing domains at this interface were modeled as cylindrical pores/channels with the anionic groups (i.e., -SO(3)(-)) assumed to be fixed on the pore wall. The interactions of each species with all other species and an applied external field were examined. Molecular-based interaction potential energies were computed in a small test element of the pore and were scaled up in terms of macroscopic variables. Evolution equations of the density and momentum of the species (water molecules and hydronium ions) were derived within a framework of nonequilibrium thermodynamics. The resulting evolution equations for the species were solved analytically using an order-of-magnitude analysis to obtain an expression for the proton conductivity. Results show that the conductivity increases with increasing water content and pore radius, and strongly depends on the separation distance between the sulfonate groups and their distribution on the pore wall. It was also determined that the conductivity of two similar pores of different radii in series is limited by the pore with the smaller radius.

Investigation of compatible anode systems for LaNbO 4-based electrolyte in novel proton conducting solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Magrasó, Anna; Fontaine, Marie-Laure

In the current manufacturing process of novel LaNbO 4-based proton conducting fuel cells a thin layer of the electrolyte is deposited by wet ceramic coating on NiO-LaNbO 4 based anode and co-sintered at 1200-1300 °C. The chemical compatibility of NiO with acceptor doped LaNbO 4 material is crucial to ensure viability of the cell, so potential effects of other phases resulting from off-stoichiometry in acceptor doped LaNbO 4 should also be explored. Compatibility of NiO with Ca-doped LaNbO 4 and its typical off-set compositions (La 3NbO 7 and LaNb 3O 9) are investigated in this work. It is shown that while NiO does not react with Ca-doped LaNbO 4, fast reaction occurs with La 3NbO 7 or LaNb 3O 9. La 3NbO 7 and NiO form a mixed conducting perovskite phase LaNi 2/3Nb 1/3O 3, while LaNb 3O 9 and NiO form either NiNb 2O 6 or Ni 4Nb 2O 9 depending on the annealing temperature. This implies that manufacturing LaNbO 4-based proton conducting fuel cells requires a strict control of the stoichiometry of the electrolyte.

A pH-dependent conformational ensemble mediates proton transport through the influenza A/M2 protein†

PubMed Central

Polishchuk, Alexei L.; Lear, James D.; Ma, Chunlong; Lamb, Robert A.; Pinto, Lawrence H.; DeGrado, William F.

2010-01-01

The influenza A M2 protein exhibits inwardly rectifying, pH-activated proton transport that saturates at low pH. A comparison of high-resolution structures of the transmembrane domain at high and low pH suggests that pH-dependent conformational changes may facilitate proton conduction by alternately changing the accessibility of the N-terminal and C-terminal regions of the channel as a proton transits through the transmembrane domain. Here, we show that M2 functionally reconstituted in liposomes populates at least three different conformational states over a physiologically relevant pH range, with transition midpoints that are consistent with previously reported His37 pKas. We then develop and test two similar, quantitative mechanistic models of proton transport, where protonation shifts the equilibrium between structural states having different proton affinities and solvent accessibilities. The models account well for a collection of experimental data sets over a wide range of pHs and voltages and require only a small number of adjustable parameters to accurately describe the data. While the kinetic models do not require any specific conformation for the protein, they nevertheless are consistent with a large body of structural information based on high-resolution NMR and crystallographic structures, optical spectroscopy, and MD calculations. PMID:20968306

An antilock molecular braking system.

PubMed

Sun, Wei-Ting; Huang, Shou-Ling; Yao, Hsuan-Hsiao; Chen, I-Chia; Lin, Ying-Chih; Yang, Jye-Shane

2012-08-17

A light-driven molecular brake displaying an antilock function is constructed by introducing a nonradiative photoinduced electron transfer (PET) decay channel to compete with the trans (brake-off) → cis (brake-on) photoisomerization. A fast release of the brake can be achieved by deactivating the PET process through addition of protons. The cycle of irradiation-protonation-irradiation-deprotonation conducts the brake function and mimics the antilock braking system (ABS) of vehicles.

COLLABORATIVE RESEARCH AND DEVELOPMENT (CR&D) Delivery Order 0067: Molecular Simulations for Hydrated Polymer Fuel Membranes

DTIC Science & Technology

2007-11-01

proton transfer. 1. INTRODUCTION While polymer electrolyte membrane fuel cells ( PEMFCs ) hold out the possibility for providing several important...Among the broader aims of the research is to develop PEMFC systems which can operate at higher temperatures than presently achievable while still...efforts have provided insight into the mechanisms which enable proton conduction in PEMFCs . Hydrated membranes are two-phase systems, an

Conductive super-hydrophobic surfaces of polyaniline modified porous anodic alumina membranes.

PubMed

Chen, Xinhua; Chen, Guangming; Ma, Yongmei; Li, Xinhong; Jiang, Lei; Wang, Fosong

2006-03-01

A conductive polymer polyaniline (PANI) was employed to achieve surfaces of both super-hydrophobic and conductive on NaOH etched porous anodic alumina (PAA) membranes. The surfaces exhibit micro- and nanostructures. In the PANI modified PAA membrane, PANI is mainly emeraldine. After the membrane was immersed in HCl, the content of the protonated nitrogen increased, which increased the conductivity.

Hybrid composite membranes of chitosan/sulfonated polyaniline/silica as polymer electrolyte membrane for fuel cells.

PubMed

Vijayakumar, Vijayalekshmi; Khastgir, Dipak

2018-01-01

A series of novel ionic cross-linked chitosan (CS) based hybrid nanocomposites were prepared by using polyaniline/nano silica (PAni/SiO 2 ) as inorganic filler and sulfuric acid as an ionic cross-linking agent. The CS-PAni/SiO 2 nanocomposites show enhanced mechanical properties and improved oxidative stabilities. These nanocomposites can be effectively used as environmental friendly proton exchange membranes. Incorporation of PAni/SiO 2 into CS matrix enhances water uptake and facilitates the phase separation which enables the formation of hydrophilic domains and improves the proton transport. Moreover, the doped polyaniline also provides some additional pathways for proton conduction. The membrane containing 3wt% loading of PAni/SiO 2 in chitosan (CS-PAni/SiO 2 -3) exhibits high proton conductivity at 80°C (8.39×10 -3 Scm -1 ) in fully hydrated state due to its excellent water retention properties. Moreover, methanol permeability of the ionic cross-linked CS-PAni/SiO 2 nanocomposite membranes significantly reduces with the addition of PAni/SiO 2 nano particles. The CS-PAni/SiO 2 -3 composite membrane displays the best overall performance as a polymer electrolyte membrane. Copyright © 2017 Elsevier Ltd. All rights reserved.

Centrality measures highlight proton traps and access points to proton highways in kinetic Monte Carlo trajectories

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krueger, Rachel A.; Haibach, Frederick G.; Fry, Dana L.

2015-04-21

A centrality measure based on the time of first returns rather than the number of steps is developed and applied to finding proton traps and access points to proton highways in the doped perovskite oxides: AZr{sub 0.875}D{sub 0.125}O{sub 3}, where A is Ba or Sr and the dopant D is Y or Al. The high centrality region near the dopant is wider in the SrZrO{sub 3} systems than the BaZrO{sub 3} systems. In the aluminum-doped systems, a region of intermediate centrality (secondary region) is found in a plane away from the dopant. Kinetic Monte Carlo (kMC) trajectories show that thismore » secondary region is an entry to fast conduction planes in the aluminum-doped systems in contrast to the highest centrality area near the dopant trap. The yttrium-doped systems do not show this secondary region because the fast conduction routes are in the same plane as the dopant and hence already in the high centrality trapped area. This centrality measure complements kMC by highlighting key areas in trajectories. The limiting activation barriers found via kMC are in very good agreement with experiments and related to the barriers to escape dopant traps.« less

Study and development of sulfated zirconia based proton exchange fuel cell membranes

NASA Astrophysics Data System (ADS)

Kemp, Brittany Wilson

With the increasing consumption of energy, fuel cells are among the most promising alternatives to fossil fuels, provided some technical challenges are overcome. Proton exchange membrane fuel cells (PEMFCs) have been investigated and improvements have been made, but the problem with NafionRTM, the main membrane for PEMFCs, has not been solved. NafionRTM restricts the membranes from operating at higher temperatures, thus preventing them from working in small electronics. The problem is to develop a novel fuel cell membrane that performs comparably to NafionRTM in PEMFCs. The membranes were fabricated by applying sulfated zirconia, via template wetting, to porous alumina membranes. The fabricated membranes showed a proton conductivity of 0.016 S/cm in comparison to the proton conductivity of Nafion RTM (0.05 S/cm). Both formic acid and methanol had a lower crossover flux through the sulfated zirconia membranes (formic acid- 2.89x10 -7 mols/cm2s and methanol-1.78x10-9 mols/cm2s) than through NafionRTM (formic acid-2.03x10 -8 mols/cm2s methanol-2.42x10-6 mols/cm 2s), indicating that a sulfated zirconia PEMFC may serve as a replacement for NafionRTM.

High Performance Proton-Conducting Solid Oxide Fuel Cells with a Layered Perovskite GdBaCuCoO5+ x Cathode

NASA Astrophysics Data System (ADS)

Zhang, Xiaozhen; Jiang, Yuhua; Hu, Xuebing; Sun, Liangliang; Ling, Yihan

2018-03-01

Proton-conducting solid oxide fuel cell (H-SOFC) based on layered perovskite type GdBaCuCoO5+x (GBCC) cathode was fabricated with in situ drop-coating BaZr0.1Ce0.7Y0.2O3-δ (BZCY) electrolyte membrane. The influences of Cu doping into Co sites of GdBaCo2O5+ x on the electrical conductivity and conduction mechanism, thermal expansion property and electrochemical performance of cathode materials and corresponding single cell were investigated. Results show that the electrical conductivity decreased and the conduction mechanism would gradually transform to the semiconductor-like behavior. A high maximum power density of 480 mW cm-2 was obtained for the anode supported NiO-BZCY/NiO-BZCY/BZCY/GBCC single cells with wet H2 fuel at 700 °C. The corresponding polarization resistance was as low as 0.17 Ω cm2. The excellent electrochemical performance of as-prepared single cell indicates that GBCC is a good candidate of cathode materials for H-SOFCs.

The K+ channel KIR2.1 functions in tandem with proton influx to mediate sour taste transduction

PubMed Central

Ye, Wenlei; Chang, Rui B.; Bushman, Jeremy D.; Tu, Yu-Hsiang; Mulhall, Eric M.; Wilson, Courtney E.; Cooper, Alexander J.; Chick, Wallace S.; Hill-Eubanks, David C.; Nelson, Mark T.; Kinnamon, Sue C.; Liman, Emily R.

2016-01-01

Sour taste is detected by a subset of taste cells on the tongue and palate epithelium that respond to acids with trains of action potentials. Entry of protons through a Zn2+-sensitive proton conductance that is specific to sour taste cells has been shown to be the initial event in sour taste transduction. Whether this conductance acts in concert with other channels sensitive to changes in intracellular pH, however, is not known. Here, we show that intracellular acidification generates excitatory responses in sour taste cells, which can be attributed to block of a resting K+ current. We identify KIR2.1 as the acid-sensitive K+ channel in sour taste cells using pharmacological and RNA expression profiling and confirm its contribution to sour taste with tissue-specific knockout of the Kcnj2 gene. Surprisingly, acid sensitivity is not conferred on sour taste cells by the specific expression of Kir2.1, but by the relatively small magnitude of the current, which makes the cells exquisitely sensitive to changes in intracellular pH. Consistent with a role of the K+ current in amplifying the sensory response, entry of protons through the Zn2+-sensitive conductance produces a transient block of the KIR2.1 current. The identification in sour taste cells of an acid-sensitive K+ channel suggests a mechanism for amplification of sour taste and may explain why weak acids that produce intracellular acidification, such as acetic acid, taste more sour than strong acids. PMID:26627720

Thermal conduction study of warm dense aluminum by proton differential heating

NASA Astrophysics Data System (ADS)

Ping, Y.; Kemp, G.; McKelvey, A.; Fernandez-Panella, A.; Shepherd, R.; Collins, G.; Sio, H.; King, J.; Freeman, R.; Hua, R.; McGuffey, C.; Kim, J.; Beg, F.

2016-10-01

A differential heating platform has been developed for thermal conduction study (Ping et al. PoP 2015), where a temperature gradient is induced and subsequent heat flow is probed by time-resolved diagnostics. An experiment using proton differential heating has been carried out at Titan laser for Au/Al targets. Two single-shot time-resolved diagnostics are employed, SOP (streaked optical pyrometry) for surface temperature and FDI (Fourier Domain Interferometry) for surface expansion. Hydrodynamic simulations show that after 15ps, absorption in underdense plasma needs to be taken into account to correctly interpret SOP data. Comparison between simulations with different thermal conductivity models and a set of data with varying target thickness will be presented. This work was performed under DOE contract DE-AC52-07NA27344 with support from OFES Early Career program and LLNL LDRD program.

Identification of a vacuolar proton channel that triggers the bioluminescent flash in dinoflagellates.

PubMed

Rodriguez, Juan D; Haq, Saddef; Bachvaroff, Tsvetan; Nowak, Kristine F; Nowak, Scott J; Morgan, Deri; Cherny, Vladimir V; Sapp, Maredith M; Bernstein, Steven; Bolt, Andrew; DeCoursey, Thomas E; Place, Allen R; Smith, Susan M E

2017-01-01

In 1972, J. Woodland Hastings and colleagues predicted the existence of a proton selective channel (HV1) that opens in response to depolarizing voltage across the vacuole membrane of bioluminescent dinoflagellates and conducts protons into specialized luminescence compartments (scintillons), thereby causing a pH drop that triggers light emission. HV1 channels were subsequently identified and demonstrated to have important functions in a multitude of eukaryotic cells. Here we report a predicted protein from Lingulodinium polyedrum that displays hallmark properties of bona fide HV1, including time-dependent opening with depolarization, perfect proton selectivity, and characteristic ΔpH dependent gating. Western blotting and fluorescence confocal microscopy of isolated L. polyedrum scintillons immunostained with antibody to LpHV1 confirm LpHV1's predicted organellar location. Proteomics analysis demonstrates that isolated scintillon preparations contain peptides that map to LpHV1. Finally, Zn2+ inhibits both LpHV1 proton current and the acid-induced flash in isolated scintillons. These results implicate LpHV1 as the voltage gated proton channel that triggers bioluminescence in L. polyedrum, confirming Hastings' hypothesis. The same channel likely mediates the action potential that communicates the signal along the tonoplast to the scintillon.

Identification of a vacuolar proton channel that triggers the bioluminescent flash in dinoflagellates

PubMed Central

Rodriguez, Juan D.; Haq, Saddef; Bachvaroff, Tsvetan; Nowak, Kristine F.; Nowak, Scott J.; Morgan, Deri; Cherny, Vladimir V.; Sapp, Maredith M.; Bernstein, Steven; Bolt, Andrew; DeCoursey, Thomas E.; Place, Allen R.; Smith, Susan M. E.

2017-01-01

In 1972, J. Woodland Hastings and colleagues predicted the existence of a proton selective channel (HV1) that opens in response to depolarizing voltage across the vacuole membrane of bioluminescent dinoflagellates and conducts protons into specialized luminescence compartments (scintillons), thereby causing a pH drop that triggers light emission. HV1 channels were subsequently identified and demonstrated to have important functions in a multitude of eukaryotic cells. Here we report a predicted protein from Lingulodinium polyedrum that displays hallmark properties of bona fide HV1, including time-dependent opening with depolarization, perfect proton selectivity, and characteristic ΔpH dependent gating. Western blotting and fluorescence confocal microscopy of isolated L. polyedrum scintillons immunostained with antibody to LpHV1 confirm LpHV1’s predicted organellar location. Proteomics analysis demonstrates that isolated scintillon preparations contain peptides that map to LpHV1. Finally, Zn2+ inhibits both LpHV1 proton current and the acid-induced flash in isolated scintillons. These results implicate LpHV1 as the voltage gated proton channel that triggers bioluminescence in L. polyedrum, confirming Hastings’ hypothesis. The same channel likely mediates the action potential that communicates the signal along the tonoplast to the scintillon. PMID:28178296

Voltage-gated proton channels: what' next?

PubMed Central

DeCoursey, Thomas E

2008-01-01

This review is an attempt to identify and place in context some of the many questions about voltage-gated proton channels that remain unsolved. As the gene was identified only 2 years ago, the situation is very different than in fields where the gene has been known for decades. For the proton channel, most of the obvious and less obvious structure–function questions are still wide open. Remarkably, the proton channel protein strongly resembles the voltage-sensing domain of many voltage-gated ion channels, and thus offers a novel approach to study gating mechanisms. Another surprise is that the proton channel appears to function as a dimer, with two separate conduction pathways. A number of significant biological questions remain in dispute, unanswered, or in some cases, not yet asked. This latter deficit is ascribable to the intrinsic difficulty in evaluating the importance of one component in a complex system, and in addition, to the lack, until recently, of a means of performing an unambiguous lesion experiment, that is, of selectively eliminating the molecule in question. We still lack a potent, selective pharmacological inhibitor, but the identification of the gene has allowed the development of powerful new tools including proton channel antibodies, siRNA and knockout mice. PMID:18801839

Head-to-head comparison of H2-receptor antagonists and proton pump inhibitors in the treatment of erosive esophagitis: A meta-analysis

PubMed Central

Wang, Wei-Hong; Huang, Jia-Qing; Zheng, Ge-Fan; Xia, Harry Hua-Xiang; Wong, Wai-Man; Lam, Shiu-Kum; Wong, Benjamin Chun-Yu

2005-01-01

AIM: To systematically evaluate the efficacy of H2-receptor antagonists (H2RAs) and proton pump inhibitors in healing erosive esophagitis (EE). METHODS: A meta-analysis was performed. A literature search was conducted in PubMed, Medline, Embase, and Cochrane databases to include randomized controlled head-to-head comparative trials evaluating the efficacy of H2RAs or proton pump inhibitors in healing EE. Relative risk (RR) and 95% confidence interval (CI) were calculated under a random-effects model. RESULTS: RRs of cumulative healing rates for each comparison at 8 wk were: high dose vs standard dose H2RAs, 1.17 (95%CI, 1.02-1.33); standard dose proton pump inhibitors vs standard dose H2RAs, 1.59 (95%CI, 1.44-1.75); standard dose other proton pump inhibitors vs standard dose omeprazole, 1.06 (95%CI, 0.98-1.06). Proton pump inhibitors produced consistently greater healing rates than H2RAs of all doses across all grades of esophagitis, including patients refractory to H2RAs. Healing rates achieved with standard dose omeprazole were similar to those with other proton pump inhibitors in all grades of esophagitis. CONCLUSION: H2RAs are less effective for treating patients with erosive esophagitis, especially in those with severe forms of esophagitis. Standard dose proton pump inhibitors are significantly more effective than H2RAs in healing esophagitis of all grades. Proton pump inhibitors given at the recommended dose are equally effective for healing esophagitis. PMID:15996033

Treatment planning, optimization, and beam delivery technqiues for intensity modulated proton therapy

NASA Astrophysics Data System (ADS)

Sengbusch, Evan R.

Physical properties of proton interactions in matter give them a theoretical advantage over photons in radiation therapy for cancer treatment, but they are seldom used relative to photons. The primary barriers to wider acceptance of proton therapy are the technical feasibility, size, and price of proton therapy systems. Several aspects of the proton therapy landscape are investigated, and new techniques for treatment planning, optimization, and beam delivery are presented. The results of these investigations suggest a means by which proton therapy can be delivered more efficiently, effectively, and to a much larger proportion of eligible patients. An analysis of the existing proton therapy market was performed. Personal interviews with over 30 radiation oncology leaders were conducted with regard to the current and future use of proton therapy. In addition, global proton therapy market projections are presented. The results of these investigations serve as motivation and guidance for the subsequent development of treatment system designs and treatment planning, optimization, and beam delivery methods. A major factor impacting the size and cost of proton treatment systems is the maximum energy of the accelerator. Historically, 250 MeV has been the accepted value, but there is minimal quantitative evidence in the literature that supports this standard. A retrospective study of 100 patients is presented that quantifies the maximum proton kinetic energy requirements for cancer treatment, and the impact of those results with regard to treatment system size, cost, and neutron production is discussed. This study is subsequently expanded to include 100 cranial stereotactic radiosurgery (SRS) patients, and the results are discussed in the context of a proposed dedicated proton SRS treatment system. Finally, novel proton therapy optimization and delivery techniques are presented. Algorithms are developed that optimize treatment plans over beam angle, spot size, spot spacing, beamlet weight, the number of delivered beamlets, and the number of delivery angles. These methods are evaluated via treatment planning studies including left-sided whole breast irradiation, lung stereotactic body radiotherapy, nasopharyngeal carcinoma, and whole brain radiotherapy with hippocampal avoidance. Improvements in efficiency and efficacy relative to traditional proton therapy and intensity modulated photon radiation therapy are discussed.

In situ formation of a 3D core-shell and triple-conducting oxygen reduction reaction electrode for proton-conducting SOFCs

NASA Astrophysics Data System (ADS)

Zhang, Zhenbao; Wang, Jian; Chen, Yubo; Tan, Shaozao; Shao, Zongping; Chen, Dengjie

2018-05-01

BaZrxCeyY1-x-yO3-δ are recognized proton-conducting electrolyte materials for proton-conducting solid oxide fuel cells (H+-SOFCs) below 650 °C. Here Co cations are incorporated into the BaZr0.4Ce0.4Y0.2O3-δ (BZCY) scaffold to generate a 3D core-shell and triple-conducting (H+/O2-/e-) electrode in situ via infiltrating and reactive sintering. The core is the bulk BZCY scaffold, while the shell is composed of the cubic Ba(Zr0.4Ce0.4Y0.2)1-xCoxO3-δ, cubic spinel Co3O4 and cubic fluorite (Ce, Zr, Y)O2. The obtained electrode exhibits an excellent compatibility with the BZCY electrolyte, and performs well in yielding a low and stable polarization resistance for oxygen reduction reaction for intermediate-temperature H+-SOFCs. In particular, it achieves polarization resistances as low as 0.094 and 0.198 Ω cm2 at 650 and 600 °C in wet air (3% H2O) when the sintering temperature for the electrode is 900 °C. In addition, a symmetrical cell also exhibits operation stability of 70 h at 650 °C. Furthermore, a fuel cell assembled with the 3D core-shell and triple-conducting electrode delivers a peak power density of ∼330 mW cm-2 at 650 °C. The substantially improved electrochemical performance and high stability are ascribed to the unique core-shell structure and the formation of Ba(Zr0.4Ce0.4Y0.2)1-xCoxO3-δ in the shell.

Method of fabricating electrode catalyst layers with directionally oriented carbon support for proton exchange membrane fuel cell

DOEpatents

Liu, Di-Jia [Naperville, IL; Yang, Junbing [Bolingbrook, IL

2012-03-20

A membrane electrode assembly (MEA) of the invention comprises an anode and a cathode and a proton conductive membrane therebetween, the anode and the cathode each comprising a patterned sheet of longitudinally aligned transition metal-containing carbon nanotubes, wherein the carbon nanotubes are in contact with and are aligned generally perpendicular to the membrane, wherein a catalytically active transition metal is incorporated throughout the nanotubes.

Identification of an HV 1 voltage-gated proton channel in insects.

PubMed

Chaves, Gustavo; Derst, Christian; Franzen, Arne; Mashimo, Yuta; Machida, Ryuichiro; Musset, Boris

2016-04-01

The voltage-gated proton channel 1 (HV 1) is an important component of the cellular proton extrusion machinery and is essential for charge compensation during the respiratory burst of phagocytes. HV 1 has been identified in a wide range of eukaryotes throughout the animal kingdom, with the exception of insects. Therefore, it has been proposed that insects do not possess an HV 1 channel. In the present study, we report the existence of an HV 1-type proton channel in insects. We searched insect transcriptome shotgun assembly (TSA) sequence databases and found putative HV 1 orthologues in various polyneopteran insects. To confirm that these putative HV 1 orthologues were functional channels, we studied the HV 1 channel of Nicoletia phytophila (NpHV 1), an insect of the Zygentoma order, in more detail. NpHV 1 comprises 239 amino acids and is 33% identical to the human voltage-gated proton channel 1. Patch clamp measurements in a heterologous expression system showed proton selectivity, as well as pH- and voltage-dependent gating. Interestingly, NpHV 1 shows slightly enhanced pH-dependent gating compared to the human channel. Mutations in the first transmembrane segment at position 66 (Asp66), the presumed selectivity filter, lead to a loss of proton-selective conduction, confirming the importance of this aspartate residue in voltage-gated proton channels. Nucleotide sequence data have been deposited in the GenBank database under accession number KT780722. © 2016 Federation of European Biochemical Societies.

Characteristics of fiber-optic radiation sensor for passive scattering proton beams

NASA Astrophysics Data System (ADS)

Son, J.; Kim, M.; Jeong, J.; Lim, Y.; Lee, S. B.; Shin, D.; Yoon, M.

2017-11-01

The aims of this study were to investigate the characteristics of a fiber-optic radiation sensor (FORS) that detects the fluorescence light produced by proton beam and to verify its effectiveness in proton therapy quality assurance (QA). Various characteristics of the FORS were investigated, such as the linearity of its relationships to the sensitive length of fiber for the proton beams of intermediate ranges (165.46 and 178.37 MeV) and to the measured dose, as well as its dose rate dependence. In addition, patient specific precription dose QA was conducted for five patients actually undergoing proton therapy and the results were compared with the doses measured using an ion chamber. The results show that the signal of the FORS is linearly related to the sensitive length of fiber and to the irradiated dose in the range from 1 to 500 cGy. The QA results obtained using the FORS system showed good agreement with the corresponding ion chamber results, with an average difference of 0.40% and a standard deviation of 0.35%. The FORS was dose-rate independent for proton currents up to 5 Gy/min. The profiles of various proton beams obtained using an array of FORS, which were measured as an application of the developed dosimetric system, closely agreed with the profiles acquired using EBT3 film. In summary, the experimental results of FORS demonstrated its effectiveness for use in various proton therapy QA tests.

Search for new high-mass phenomena in the dilepton final state using 36 fb-1 of proton-proton collision data at √{s}=13 TeV with the ATLAS detector

NASA Astrophysics Data System (ADS)

Aaboud, M.; Aad, G.; Abbott, B.; Abdinov, O.; Abeloos, B.; Abidi, S. H.; AbouZeid, O. S.; Abraham, N. L.; Abramowicz, H.; Abreu, H.; Abreu, R.; Abulaiti, Y.; Acharya, B. S.; Adachi, S.; Adamczyk, L.; Adelman, J.; Adersberger, M.; Adye, T.; Affolder, A. A.; Agatonovic-Jovin, T.; Agheorghiesei, C.; Aguilar-Saavedra, J. A.; Ahlen, S. P.; Ahmadov, F.; Aielli, G.; Akatsuka, S.; Akerstedt, H.; Åkesson, T. P. A.; Akilli, E.; Akimov, A. V.; Alberghi, G. L.; Albert, J.; Albicocco, P.; Alconada Verzini, M. J.; Alderweireldt, S. C.; Aleksa, M.; Aleksandrov, I. N.; Alexa, C.; Alexander, G.; Alexopoulos, T.; Alhroob, M.; Ali, B.; Aliev, M.; Alimonti, G.; Alison, J.; Alkire, S. P.; Allbrooke, B. M. M.; Allen, B. W.; Allport, P. P.; Aloisio, A.; Alonso, A.; Alonso, F.; Alpigiani, C.; Alshehri, A. A.; Alstaty, M. I.; Alvarez Gonzalez, B.; Álvarez Piqueras, D.; Alviggi, M. G.; Amadio, B. T.; Amaral Coutinho, Y.; Amelung, C.; Amidei, D.; Amor Dos Santos, S. P.; Amorim, A.; Amoroso, S.; Amundsen, G.; Anastopoulos, C.; Ancu, L. S.; Andari, N.; Andeen, T.; Anders, C. F.; Anders, J. K.; Anderson, K. J.; Andreazza, A.; Andrei, V.; Angelidakis, S.; Angelozzi, I.; Angerami, A.; Anisenkov, A. V.; Anjos, N.; Annovi, A.; Antel, C.; Antonelli, M.; Antonov, A.; Antrim, D. J.; Anulli, F.; Aoki, M.; Aperio Bella, L.; Arabidze, G.; Arai, Y.; Araque, J. P.; Araujo Ferraz, V.; Arce, A. T. H.; Ardell, R. E.; Arduh, F. A.; Arguin, J.-F.; Argyropoulos, S.; Arik, M.; Armbruster, A. J.; Armitage, L. J.; Arnaez, O.; Arnold, H.; Arratia, M.; Arslan, O.; Artamonov, A.; Artoni, G.; Artz, S.; Asai, S.; Asbah, N.; Ashkenazi, A.; Asquith, L.; Assamagan, K.; Astalos, R.; Atkinson, M.; Atlay, N. B.; Augsten, K.; Avolio, G.; Axen, B.; Ayoub, M. K.; Azuelos, G.; Baas, A. E.; Baca, M. J.; Bachacou, H.; Bachas, K.; Backes, M.; Backhaus, M.; Bagnaia, P.; Bahmani, M.; Bahrasemani, H.; Baines, J. T.; Bajic, M.; Baker, O. K.; Baldin, E. M.; Balek, P.; Balli, F.; Balunas, W. K.; Banas, E.; Bandyopadhyay, A.; Banerjee, Sw.; Bannoura, A. A. E.; Barak, L.; Barberio, E. L.; Barberis, D.; Barbero, M.; Barillari, T.; Barisits, M.-S.; Barkeloo, J. T.; Barklow, T.; Barlow, N.; Barnes, S. L.; Barnett, B. M.; Barnett, R. M.; Barnovska-Blenessy, Z.; Baroncelli, A.; Barone, G.; Barr, A. J.; Barranco Navarro, L.; Barreiro, F.; Barreiro Guimarães da Costa, J.; Bartoldus, R.; Barton, A. E.; Bartos, P.; Basalaev, A.; Bassalat, A.; Bates, R. L.; Batista, S. J.; Batley, J. R.; Battaglia, M.; Bauce, M.; Bauer, F.; Bawa, H. S.; Beacham, J. B.; Beattie, M. D.; Beau, T.; Beauchemin, P. H.; Bechtle, P.; Beck, H. P.; Beck, H. C.; Becker, K.; Becker, M.; Beckingham, M.; Becot, C.; Beddall, A. J.; Beddall, A.; Bednyakov, V. A.; Bedognetti, M.; Bee, C. P.; Beermann, T. A.; Begalli, M.; Begel, M.; Behr, J. K.; Bell, A. S.; Bella, G.; Bellagamba, L.; Bellerive, A.; Bellomo, M.; Belotskiy, K.; Beltramello, O.; Belyaev, N. L.; Benary, O.; Benchekroun, D.; Bender, M.; Bendtz, K.; Benekos, N.; Benhammou, Y.; Benhar Noccioli, E.; Benitez, J.; Benjamin, D. P.; Benoit, M.; Bensinger, J. R.; Bentvelsen, S.; Beresford, L.; Beretta, M.; Berge, D.; Bergeaas Kuutmann, E.; Berger, N.; Beringer, J.; Berlendis, S.; Bernard, N. R.; Bernardi, G.; Bernius, C.; Bernlochner, F. U.; Berry, T.; Berta, P.; Bertella, C.; Bertoli, G.; Bertolucci, F.; Bertram, I. A.; Bertsche, C.; Bertsche, D.; Besjes, G. J.; Bessidskaia Bylund, O.; Bessner, M.; Besson, N.; Betancourt, C.; Bethani, A.; Bethke, S.; Bevan, A. J.; Beyer, J.; Bianchi, R. M.; Biebel, O.; Biedermann, D.; Bielski, R.; Bierwagen, K.; Biesuz, N. V.; Biglietti, M.; Billoud, T. R. V.; Bilokon, H.; Bindi, M.; Bingul, A.; Bini, C.; Biondi, S.; Bisanz, T.; Bittrich, C.; Bjergaard, D. M.; Black, C. W.; Black, J. E.; Black, K. M.; Blair, R. E.; Blazek, T.; Bloch, I.; Blocker, C.; Blue, A.; Blum, W.; Blumenschein, U.; Blunier, S.; Bobbink, G. J.; Bobrovnikov, V. S.; Bocchetta, S. S.; Bocci, A.; Bock, C.; Boehler, M.; Boerner, D.; Bogavac, D.; Bogdanchikov, A. G.; Bohm, C.; Boisvert, V.; Bokan, P.; Bold, T.; Boldyrev, A. S.; Bolz, A. E.; Bomben, M.; Bona, M.; Boonekamp, M.; Borisov, A.; Borissov, G.; Bortfeldt, J.; Bortoletto, D.; Bortolotto, V.; Boscherini, D.; Bosman, M.; Bossio Sola, J. D.; Boudreau, J.; Bouffard, J.; Bouhova-Thacker, E. V.; Boumediene, D.; Bourdarios, C.; Boutle, S. K.; Boveia, A.; Boyd, J.; Boyko, I. R.; Bracinik, J.; Brandt, A.; Brandt, G.; Brandt, O.; Bratzler, U.; Brau, B.; Brau, J. E.; Breaden Madden, W. D.; Brendlinger, K.; Brennan, A. J.; Brenner, L.; Brenner, R.; Bressler, S.; Briglin, D. L.; Bristow, T. M.; Britton, D.; Britzger, D.; Brochu, F. M.; Brock, I.; Brock, R.; Brooijmans, G.; Brooks, T.; Brooks, W. K.; Brosamer, J.; Brost, E.; Broughton, J. H.; Bruckman de Renstrom, P. A.; Bruncko, D.; Bruni, A.; Bruni, G.; Bruni, L. S.; Brunt, BH; Bruschi, M.; Bruscino, N.; Bryant, P.; Bryngemark, L.; Buanes, T.; Buat, Q.; Buchholz, P.; Buckley, A. G.; Budagov, I. A.; Buehrer, F.; Bugge, M. K.; Bulekov, O.; Bullock, D.; Burch, T. J.; Burdin, S.; Burgard, C. D.; Burger, A. M.; Burghgrave, B.; Burka, K.; Burke, S.; Burmeister, I.; Burr, J. T. P.; Busato, E.; Büscher, D.; Büscher, V.; Bussey, P.; Butler, J. M.; Buttar, C. M.; Butterworth, J. M.; Butti, P.; Buttinger, W.; Buzatu, A.; Buzykaev, A. R.; Cabrera Urbán, S.; Caforio, D.; Cairo, V. M.; Cakir, O.; Calace, N.; Calafiura, P.; Calandri, A.; Calderini, G.; Calfayan, P.; Callea, G.; Caloba, L. P.; Calvente Lopez, S.; Calvet, D.; Calvet, S.; Calvet, T. P.; Camacho Toro, R.; Camarda, S.; Camarri, P.; Cameron, D.; Caminal Armadans, R.; Camincher, C.; Campana, S.; Campanelli, M.; Camplani, A.; Campoverde, A.; Canale, V.; Cano Bret, M.; Cantero, J.; Cao, T.; Capeans Garrido, M. D. M.; Caprini, I.; Caprini, M.; Capua, M.; Carbone, R. M.; Cardarelli, R.; Cardillo, F.; Carli, I.; Carli, T.; Carlino, G.; Carlson, B. T.; Carminati, L.; Carney, R. M. D.; Caron, S.; Carquin, E.; Carrá, S.; Carrillo-Montoya, G. D.; Carvalho, J.; Casadei, D.; Casado, M. P.; Casolino, M.; Casper, D. W.; Castelijn, R.; Castillo Gimenez, V.; Castro, N. F.; Catinaccio, A.; Catmore, J. R.; Cattai, A.; Caudron, J.; Cavaliere, V.; Cavallaro, E.; Cavalli, D.; Cavalli-Sforza, M.; Cavasinni, V.; Celebi, E.; Ceradini, F.; Cerda Alberich, L.; Cerqueira, A. S.; Cerri, A.; Cerrito, L.; Cerutti, F.; Cervelli, A.; Cetin, S. A.; Chafaq, A.; Chakraborty, D.; Chan, S. K.; Chan, W. S.; Chan, Y. L.; Chang, P.; Chapman, J. D.; Charlton, D. G.; Chau, C. C.; Chavez Barajas, C. A.; Che, S.; Cheatham, S.; Chegwidden, A.; Chekanov, S.; Chekulaev, S. V.; Chelkov, G. A.; Chelstowska, M. A.; Chen, C.; Chen, H.; Chen, J.; Chen, S.; Chen, S.; Chen, X.; Chen, Y.; Cheng, H. C.; Cheng, H. J.; Cheplakov, A.; Cheremushkina, E.; Cherkaoui El Moursli, R.; Cheu, E.; Cheung, K.; Chevalier, L.; Chiarella, V.; Chiarelli, G.; Chiodini, G.; Chisholm, A. S.; Chitan, A.; Chiu, Y. H.; Chizhov, M. V.; Choi, K.; Chomont, A. R.; Chouridou, S.; Chow, Y. S.; Christodoulou, V.; Chu, M. C.; Chudoba, J.; Chuinard, A. J.; Chwastowski, J. J.; Chytka, L.; Ciftci, A. K.; Cinca, D.; Cindro, V.; Cioara, I. A.; Ciocca, C.; Ciocio, A.; Cirotto, F.; Citron, Z. H.; Citterio, M.; Ciubancan, M.; Clark, A.; Clark, B. L.; Clark, M. R.; Clark, P. J.; Clarke, R. N.; Clement, C.; Coadou, Y.; Cobal, M.; Coccaro, A.; Cochran, J.; Colasurdo, L.; Cole, B.; Colijn, A. P.; Collot, J.; Colombo, T.; Conde Muiño, P.; Coniavitis, E.; Connell, S. H.; Connelly, I. A.; Constantinescu, S.; Conti, G.; Conventi, F.; Cooke, M.; Cooper-Sarkar, A. M.; Cormier, F.; Cormier, K. J. R.; Corradi, M.; Corriveau, F.; Cortes-Gonzalez, A.; Cortiana, G.; Costa, G.; Costa, M. J.; Costanzo, D.; Cottin, G.; Cowan, G.; Cox, B. E.; Cranmer, K.; Crawley, S. J.; Creager, R. A.; Cree, G.; Crépé-Renaudin, S.; Crescioli, F.; Cribbs, W. A.; Cristinziani, M.; Croft, V.; Crosetti, G.; Cueto, A.; Cuhadar Donszelmann, T.; Cukierman, A. R.; Cummings, J.; Curatolo, M.; Cúth, J.; Czekierda, S.; Czodrowski, P.; D'amen, G.; D'Auria, S.; D'eramo, L.; D'Onofrio, M.; Da Cunha Sargedas De Sousa, M. J.; Da Via, C.; Dabrowski, W.; Dado, T.; Dai, T.; Dale, O.; Dallaire, F.; Dallapiccola, C.; Dam, M.; Dandoy, J. R.; Daneri, M. F.; Dang, N. P.; Daniells, A. C.; Dann, N. S.; Danninger, M.; Dano Hoffmann, M.; Dao, V.; Darbo, G.; Darmora, S.; Dassoulas, J.; Dattagupta, A.; Daubney, T.; Davey, W.; David, C.; Davidek, T.; Davis, D. R.; Davison, P.; Dawe, E.; Dawson, I.; De, K.; de Asmundis, R.; De Benedetti, A.; De Castro, S.; De Cecco, S.; De Groot, N.; de Jong, P.; De la Torre, H.; De Lorenzi, F.; De Maria, A.; De Pedis, D.; De Salvo, A.; De Sanctis, U.; De Santo, A.; De Vasconcelos Corga, K.; De Vivie De Regie, J. B.; Dearnaley, W. J.; Debbe, R.; Debenedetti, C.; Dedovich, D. V.; Dehghanian, N.; Deigaard, I.; Del Gaudio, M.; Del Peso, J.; Delgove, D.; Deliot, F.; Delitzsch, C. M.; Dell'Acqua, A.; Dell'Asta, L.; Dell'Orso, M.; Della Pietra, M.; della Volpe, D.; Delmastro, M.; Delporte, C.; Delsart, P. A.; DeMarco, D. A.; Demers, S.; Demichev, M.; Demilly, A.; Denisov, S. P.; Denysiuk, D.; Derendarz, D.; Derkaoui, J. E.; Derue, F.; Dervan, P.; Desch, K.; Deterre, C.; Dette, K.; Devesa, M. R.; Deviveiros, P. O.; Dewhurst, A.; Dhaliwal, S.; Di Bello, F. A.; Di Ciaccio, A.; Di Ciaccio, L.; Di Clemente, W. K.; Di Donato, C.; Di Girolamo, A.; Di Girolamo, B.; Di Micco, B.; Di Nardo, R.; Di Petrillo, K. F.; Di Simone, A.; Di Sipio, R.; Di Valentino, D.; Diaconu, C.; Diamond, M.; Dias, F. A.; Diaz, M. A.; Diehl, E. B.; Dietrich, J.; Díez Cornell, S.; Dimitrievska, A.; Dingfelder, J.; Dita, P.; Dita, S.; Dittus, F.; Djama, F.; Djobava, T.; Djuvsland, J. I.; do Vale, M. A. B.; Dobos, D.; Dobre, M.; Doglioni, C.; Dolejsi, J.; Dolezal, Z.; Donadelli, M.; Donati, S.; Dondero, P.; Donini, J.; Dopke, J.; Doria, A.; Dova, M. T.; Doyle, A. T.; Drechsler, E.; Dreyer, E.; Dris, M.; Du, Y.; Duarte-Campderros, J.; Dubreuil, A.; Duchovni, E.; Duckeck, G.; Ducourthial, A.; Ducu, O. A.; Duda, D.; Dudarev, A.; Dudder, A. Chr.; Duffield, E. M.; Duflot, L.; Dührssen, M.; Dumancic, M.; Dumitriu, A. E.; Duncan, A. K.; Dunford, M.; Duran Yildiz, H.; Düren, M.; Durglishvili, A.; Duschinger, D.; Dutta, B.; Duvnjak, D.; Dyndal, M.; Dziedzic, B. S.; Eckardt, C.; Ecker, K. M.; Edgar, R. C.; Eifert, T.; Eigen, G.; Einsweiler, K.; Ekelof, T.; El Kacimi, M.; El Kosseifi, R.; Ellajosyula, V.; Ellert, M.; Elles, S.; Ellinghaus, F.; Elliot, A. A.; Ellis, N.; Elmsheuser, J.; Elsing, M.; Emeliyanov, D.; Enari, Y.; Endner, O. C.; Ennis, J. S.; Erdmann, J.; Ereditato, A.; Ernst, M.; Errede, S.; Escalier, M.; Escobar, C.; Esposito, B.; Estrada Pastor, O.; Etienvre, A. I.; Etzion, E.; Evans, H.; Ezhilov, A.; Ezzi, M.; Fabbri, F.; Fabbri, L.; Fabiani, V.; Facini, G.; Fakhrutdinov, R. M.; Falciano, S.; Falke, P. J.; Falla, R. J.; Faltova, J.; Fang, Y.; Fanti, M.; Farbin, A.; Farilla, A.; Farina, C.; Farina, E. M.; Farooque, T.; Farrell, S.; Farrington, S. M.; Farthouat, P.; Fassi, F.; Fassnacht, P.; Fassouliotis, D.; Faucci Giannelli, M.; Favareto, A.; Fawcett, W. J.; Fayard, L.; Fedin, O. L.; Fedorko, W.; Feigl, S.; Feligioni, L.; Feng, C.; Feng, E. J.; Feng, H.; Fenton, M. J.; Fenyuk, A. B.; Feremenga, L.; Fernandez Martinez, P.; Fernandez Perez, S.; Ferrando, J.; Ferrari, A.; Ferrari, P.; Ferrari, R.; Ferreira de Lima, D. E.; Ferrer, A.; Ferrere, D.; Ferretti, C.; Fiedler, F.; Filipčič, A.; Filipuzzi, M.; Filthaut, F.; Fincke-Keeler, M.; Finelli, K. D.; Fiolhais, M. C. N.; Fiorini, L.; Fischer, A.; Fischer, C.; Fischer, J.; Fisher, W. C.; Flaschel, N.; Fleck, I.; Fleischmann, P.; Fletcher, R. R. M.; Flick, T.; Flierl, B. M.; Flores Castillo, L. R.; Flowerdew, M. J.; Forcolin, G. T.; Formica, A.; Förster, F. A.; Forti, A.; Foster, A. G.; Fournier, D.; Fox, H.; Fracchia, S.; Francavilla, P.; Franchini, M.; Franchino, S.; Francis, D.; Franconi, L.; Franklin, M.; Frate, M.; Fraternali, M.; Freeborn, D.; Fressard-Batraneanu, S. M.; Freund, B.; Froidevaux, D.; Frost, J. A.; Fukunaga, C.; Fusayasu, T.; Fuster, J.; Gabaldon, C.; Gabizon, O.; Gabrielli, A.; Gabrielli, A.; Gach, G. P.; Gadatsch, S.; Gadomski, S.; Gagliardi, G.; Gagnon, L. G.; Galea, C.; Galhardo, B.; Gallas, E. J.; Gallop, B. J.; Gallus, P.; Galster, G.; Gan, K. K.; Ganguly, S.; Gao, Y.; Gao, Y. S.; Garay Walls, F. M.; García, C.; García Navarro, J. E.; García Pascual, J. A.; Garcia-Sciveres, M.; Gardner, R. W.; Garelli, N.; Garonne, V.; Gascon Bravo, A.; Gasnikova, K.; Gatti, C.; Gaudiello, A.; Gaudio, G.; Gavrilenko, I. L.; Gay, C.; Gaycken, G.; Gazis, E. N.; Gee, C. N. P.; Geisen, J.; Geisen, M.; Geisler, M. P.; Gellerstedt, K.; Gemme, C.; Genest, M. 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S.; Osculati, B.; Ospanov, R.; Otero y Garzon, G.; Otono, H.; Ouchrif, M.; Ould-Saada, F.; Ouraou, A.; Oussoren, K. P.; Ouyang, Q.; Owen, M.; Owen, R. E.; Ozcan, V. E.; Ozturk, N.; Pachal, K.; Pacheco Pages, A.; Pacheco Rodriguez, L.; Padilla Aranda, C.; Pagan Griso, S.; Paganini, M.; Paige, F.; Palacino, G.; Palazzo, S.; Palestini, S.; Palka, M.; Pallin, D.; Panagiotopoulou, E. St.; Panagoulias, I.; Pandini, C. E.; Panduro Vazquez, J. G.; Pani, P.; Panitkin, S.; Pantea, D.; Paolozzi, L.; Papadopoulou, Th. D.; Papageorgiou, K.; Paramonov, A.; Paredes Hernandez, D.; Parker, A. J.; Parker, M. A.; Parker, K. A.; Parodi, F.; Parsons, J. A.; Parzefall, U.; Pascuzzi, V. R.; Pasner, J. M.; Pasqualucci, E.; Passaggio, S.; Pastore, Fr.; Pataraia, S.; Pater, J. R.; Pauly, T.; Pearson, B.; Pedraza Lopez, S.; Pedro, R.; Peleganchuk, S. V.; Penc, O.; Peng, C.; Peng, H.; Penwell, J.; Peralva, B. S.; Perego, M. M.; Perepelitsa, D. V.; Peri, F.; Perini, L.; Pernegger, H.; Perrella, S.; Peschke, R.; Peshekhonov, V. D.; Peters, K.; Peters, R. F. Y.; Petersen, B. A.; Petersen, T. C.; Petit, E.; Petridis, A.; Petridou, C.; Petroff, P.; Petrolo, E.; Petrov, M.; Petrucci, F.; Pettersson, N. E.; Peyaud, A.; Pezoa, R.; Phillips, F. H.; Phillips, P. W.; Piacquadio, G.; Pianori, E.; Picazio, A.; Piccaro, E.; Pickering, M. A.; Piegaia, R.; Pilcher, J. E.; Pilkington, A. D.; Pin, A. W. J.; Pinamonti, M.; Pinfold, J. L.; Pirumov, H.; Pitt, M.; Plazak, L.; Pleier, M.-A.; Pleskot, V.; Plotnikova, E.; Pluth, D.; Podberezko, P.; Poettgen, R.; Poggi, R.; Poggioli, L.; Pohl, D.; Polesello, G.; Poley, A.; Policicchio, A.; Polifka, R.; Polini, A.; Pollard, C. S.; Polychronakos, V.; Pommès, K.; Ponomarenko, D.; Pontecorvo, L.; Popeneciu, G. A.; Pospisil, S.; Potamianos, K.; Potrap, I. N.; Potter, C. J.; Poulsen, T.; Poveda, J.; Pozo Astigarraga, M. E.; Pralavorio, P.; Pranko, A.; Prell, S.; Price, D.; Primavera, M.; Prince, S.; Proklova, N.; Prokofiev, K.; Prokoshin, F.; Protopopescu, S.; Proudfoot, J.; Przybycien, M.; Puri, A.; Puzo, P.; Qian, J.; Qin, G.; Qin, Y.; Quadt, A.; Queitsch-Maitland, M.; Quilty, D.; Raddum, S.; Radeka, V.; Radescu, V.; Radhakrishnan, S. K.; Radloff, P.; Rados, P.; Ragusa, F.; Rahal, G.; Raine, J. A.; Rajagopalan, S.; Rangel-Smith, C.; Rashid, T.; Raspopov, S.; Ratti, M. G.; Rauch, D. M.; Rauscher, F.; Rave, S.; Ravinovich, I.; Rawling, J. H.; Raymond, M.; Read, A. L.; Readioff, N. P.; Reale, M.; Rebuzzi, D. M.; Redelbach, A.; Redlinger, G.; Reece, R.; Reed, R. G.; Reeves, K.; Rehnisch, L.; Reichert, J.; Reiss, A.; Rembser, C.; Ren, H.; Rescigno, M.; Resconi, S.; Resseguie, E. D.; Rettie, S.; Reynolds, E.; Rezanova, O. L.; Reznicek, P.; Rezvani, R.; Richter, R.; Richter, S.; Richter-Was, E.; Ricken, O.; Ridel, M.; Rieck, P.; Riegel, C. J.; Rieger, J.; Rifki, O.; Rijssenbeek, M.; Rimoldi, A.; Rimoldi, M.; Rinaldi, L.; Ripellino, G.; Ristić, B.; Ritsch, E.; Riu, I.; Rizatdinova, F.; Rizvi, E.; Rizzi, C.; Roberts, R. T.; Robertson, S. H.; Robichaud-Veronneau, A.; Robinson, D.; Robinson, J. E. M.; Robson, A.; Rocco, E.; Roda, C.; Rodina, Y.; Rodriguez Bosca, S.; Rodriguez Perez, A.; Rodriguez Rodriguez, D.; Roe, S.; Rogan, C. S.; Røhne, O.; Roloff, J.; Romaniouk, A.; Romano, M.; Romano Saez, S. M.; Romero Adam, E.; Rompotis, N.; Ronzani, M.; Roos, L.; Rosati, S.; Rosbach, K.; Rose, P.; Rosien, N.-A.; Rossi, E.; Rossi, L. P.; Rosten, J. H. N.; Rosten, R.; Rotaru, M.; Rothberg, J.; Rousseau, D.; Rozanov, A.; Rozen, Y.; Ruan, X.; Rubbo, F.; Rühr, F.; Ruiz-Martinez, A.; Rurikova, Z.; Rusakovich, N. A.; Russell, H. L.; Rutherfoord, J. P.; Ruthmann, N.; Ryabov, Y. F.; Rybar, M.; Rybkin, G.; Ryu, S.; Ryzhov, A.; Rzehorz, G. F.; Saavedra, A. F.; Sabato, G.; Sacerdoti, S.; Sadrozinski, H. F.-W.; Sadykov, R.; Safai Tehrani, F.; Saha, P.; Sahinsoy, M.; Saimpert, M.; Saito, M.; Saito, T.; Sakamoto, H.; Sakurai, Y.; Salamanna, G.; Salazar Loyola, J. E.; Salek, D.; Sales De Bruin, P. H.; Salihagic, D.; Salnikov, A.; Salt, J.; Salvatore, D.; Salvatore, F.; Salvucci, A.; Salzburger, A.; Sammel, D.; Sampsonidis, D.; Sampsonidou, D.; Sánchez, J.; Sanchez Martinez, V.; Sanchez Pineda, A.; Sandaker, H.; Sandbach, R. L.; Sander, C. O.; Sandhoff, M.; Sandoval, C.; Sankey, D. P. C.; Sannino, M.; Sano, Y.; Sansoni, A.; Santoni, C.; Santos, H.; Santoyo Castillo, I.; Sapronov, A.; Saraiva, J. G.; Sarrazin, B.; Sasaki, O.; Sato, K.; Sauvan, E.; Savage, G.; Savard, P.; Savic, N.; Sawyer, C.; Sawyer, L.; Saxon, J.; Sbarra, C.; Sbrizzi, A.; Scanlon, T.; Scannicchio, D. A.; Scarcella, M.; Schaarschmidt, J.; Schacht, P.; Schachtner, B. M.; Schaefer, D.; Schaefer, L.; Schaefer, R.; Schaeffer, J.; Schaepe, S.; Schaetzel, S.; Schäfer, U.; Schaffer, A. C.; Schaile, D.; Schamberger, R. D.; Schegelsky, V. A.; Scheirich, D.; Schernau, M.; Schiavi, C.; Schier, S.; Schildgen, L. K.; Schillo, C.; Schioppa, M.; Schlenker, S.; Schmidt-Sommerfeld, K. R.; Schmieden, K.; Schmitt, C.; Schmitt, S.; Schmitz, S.; Schnoor, U.; Schoeffel, L.; Schoening, A.; Schoenrock, B. D.; Schopf, E.; Schott, M.; Schouwenberg, J. F. P.; Schovancova, J.; Schramm, S.; Schuh, N.; Schulte, A.; Schultens, M. J.; Schultz-Coulon, H.-C.; Schulz, H.; Schumacher, M.; Schumm, B. A.; Schune, Ph.; Schwartzman, A.; Schwarz, T. A.; Schweiger, H.; Schwemling, Ph.; Schwienhorst, R.; Schwindling, J.; Sciandra, A.; Sciolla, G.; Scornajenghi, M.; Scuri, F.; Scutti, F.; Searcy, J.; Seema, P.; Seidel, S. C.; Seiden, A.; Seixas, J. M.; Sekhniaidze, G.; Sekhon, K.; Sekula, S. J.; Semprini-Cesari, N.; Senkin, S.; Serfon, C.; Serin, L.; Serkin, L.; Sessa, M.; Seuster, R.; Severini, H.; Sfiligoj, T.; Sforza, F.; Sfyrla, A.; Shabalina, E.; Shaikh, N. W.; Shan, L. Y.; Shang, R.; Shank, J. T.; Shapiro, M.; Shatalov, P. B.; Shaw, K.; Shaw, S. M.; Shcherbakova, A.; Shehu, C. Y.; Shen, Y.; Sherafati, N.; Sherwood, P.; Shi, L.; Shimizu, S.; Shimmin, C. O.; Shimojima, M.; Shipsey, I. P. J.; Shirabe, S.; Shiyakova, M.; Shlomi, J.; Shmeleva, A.; Shoaleh Saadi, D.; Shochet, M. J.; Shojaii, S.; Shope, D. R.; Shrestha, S.; Shulga, E.; Shupe, M. A.; Sicho, P.; Sickles, A. M.; Sidebo, P. E.; Sideras Haddad, E.; Sidiropoulou, O.; Sidoti, A.; Siegert, F.; Sijacki, Dj.; Silva, J.; Silverstein, S. B.; Simak, V.; Simic, Lj.; Simion, S.; Simioni, E.; Simmons, B.; Simon, M.; Sinervo, P.; Sinev, N. B.; Sioli, M.; Siragusa, G.; Siral, I.; Sivoklokov, S. Yu.; Sjölin, J.; Skinner, M. B.; Skubic, P.; Slater, M.; Slavicek, T.; Slawinska, M.; Sliwa, K.; Slovak, R.; Smakhtin, V.; Smart, B. H.; Smiesko, J.; Smirnov, N.; Smirnov, S. Yu.; Smirnov, Y.; Smirnova, L. N.; Smirnova, O.; Smith, J. W.; Smith, M. N. K.; Smith, R. W.; Smizanska, M.; Smolek, K.; Snesarev, A. A.; Snyder, I. M.; Snyder, S.; Sobie, R.; Socher, F.; Soffer, A.; Søgaard, A.; Soh, D. A.; Sokhrannyi, G.; Solans Sanchez, C. A.; Solar, M.; Soldatov, E. Yu.; Soldevila, U.; Solodkov, A. A.; Soloshenko, A.; Solovyanov, O. V.; Solovyev, V.; Sommer, P.; Son, H.; Sopczak, A.; Sosa, D.; Sotiropoulou, C. L.; Soualah, R.; Soukharev, A. M.; South, D.; Sowden, B. C.; Spagnolo, S.; Spalla, M.; Spangenberg, M.; Spanò, F.; Sperlich, D.; Spettel, F.; Spieker, T. M.; Spighi, R.; Spigo, G.; Spiller, L. A.; Spousta, M.; St. Denis, R. D.; Stabile, A.; Stamen, R.; Stamm, S.; Stanecka, E.; Stanek, R. W.; Stanescu, C.; Stanitzki, M. M.; Stapf, B. S.; Stapnes, S.; Starchenko, E. A.; Stark, G. H.; Stark, J.; Stark, S. H.; Staroba, P.; Starovoitov, P.; Stärz, S.; Staszewski, R.; Steinberg, P.; Stelzer, B.; Stelzer, H. J.; Stelzer-Chilton, O.; Stenzel, H.; Stewart, G. A.; Stockton, M. C.; Stoebe, M.; Stoicea, G.; Stolte, P.; Stonjek, S.; Stradling, A. R.; Straessner, A.; Stramaglia, M. E.; Strandberg, J.; Strandberg, S.; Strauss, M.; Strizenec, P.; Ströhmer, R.; Strom, D. M.; Stroynowski, R.; Strubig, A.; Stucci, S. A.; Stugu, B.; Styles, N. A.; Su, D.; Su, J.; Suchek, S.; Sugaya, Y.; Suk, M.; Sulin, V. V.; Sultan, DMS; Sultansoy, S.; Sumida, T.; Sun, S.; Sun, X.; Suruliz, K.; Suster, C. J. E.; Sutton, M. R.; Suzuki, S.; Svatos, M.; Swiatlowski, M.; Swift, S. P.; Sykora, I.; Sykora, T.; Ta, D.; Tackmann, K.; Taenzer, J.; Taffard, A.; Tafirout, R.; Tahirovic, E.; Taiblum, N.; Takai, H.; Takashima, R.; Takasugi, E. H.; Takeshita, T.; Takubo, Y.; Talby, M.; Talyshev, A. A.; Tanaka, J.; Tanaka, M.; Tanaka, R.; Tanaka, S.; Tanioka, R.; Tannenwald, B. B.; Tapia Araya, S.; Tapprogge, S.; Tarem, S.; Tartarelli, G. F.; Tas, P.; Tasevsky, M.; Tashiro, T.; Tassi, E.; Tavares Delgado, A.; Tayalati, Y.; Taylor, A. C.; Taylor, G. N.; Taylor, P. T. E.; Taylor, W.; Teixeira-Dias, P.; Temple, D.; Ten Kate, H.; Teng, P. K.; Teoh, J. J.; Tepel, F.; Terada, S.; Terashi, K.; Terron, J.; Terzo, S.; Testa, M.; Teuscher, R. J.; Theveneaux-Pelzer, T.; Thiele, F.; Thomas, J. P.; Thomas-Wilsker, J.; Thompson, P. D.; Thompson, A. S.; Thomsen, L. A.; Thomson, E.; Tibbetts, M. J.; Ticse Torres, R. E.; Tikhomirov, V. O.; Tikhonov, Yu. A.; Timoshenko, S.; Tipton, P.; Tisserant, S.; Todome, K.; Todorova-Nova, S.; Todt, S.; Tojo, J.; Tokár, S.; Tokushuku, K.; Tolley, E.; Tomlinson, L.; Tomoto, M.; Tompkins, L.; Toms, K.; Tong, B.; Tornambe, P.; Torrence, E.; Torres, H.; Torró Pastor, E.; Toth, J.; Touchard, F.; Tovey, D. R.; Treado, C. J.; Trefzger, T.; Tresoldi, F.; Tricoli, A.; Trigger, I. M.; Trincaz-Duvoid, S.; Tripiana, M. F.; Trischuk, W.; Trocmé, B.; Trofymov, A.; Troncon, C.; Trottier-McDonald, M.; Trovatelli, M.; Truong, L.; Trzebinski, M.; Trzupek, A.; Tsang, K. W.; Tseng, J. C.-L.; Tsiareshka, P. V.; Tsipolitis, G.; Tsirintanis, N.; Tsiskaridze, S.; Tsiskaridze, V.; Tskhadadze, E. G.; Tsui, K. M.; Tsukerman, I. I.; Tsulaia, V.; Tsuno, S.; Tsybychev, D.; Tu, Y.; Tudorache, A.; Tudorache, V.; Tulbure, T. T.; Tuna, A. N.; Tupputi, S. A.; Turchikhin, S.; Turgeman, D.; Cakir, I. Turk; Turra, R.; Tuts, P. M.; Ucchielli, G.; Ueda, I.; Ughetto, M.; Ukegawa, F.; Unal, G.; Undrus, A.; Unel, G.; Ungaro, F. C.; Unno, Y.; Unverdorben, C.; Urban, J.; Urquijo, P.; Urrejola, P.; Usai, G.; Usui, J.; Vacavant, L.; Vacek, V.; Vachon, B.; Vadla, K. O. H.; Vaidya, A.; Valderanis, C.; Valdes Santurio, E.; Valente, M.; Valentinetti, S.; Valero, A.; Valéry, L.; Valkar, S.; Vallier, A.; Valls Ferrer, J. A.; Van Den Wollenberg, W.; van der Graaf, H.; van Gemmeren, P.; Van Nieuwkoop, J.; van Vulpen, I.; van Woerden, M. C.; Vanadia, M.; Vandelli, W.; Vaniachine, A.; Vankov, P.; Vardanyan, G.; Vari, R.; Varnes, E. W.; Varni, C.; Varol, T.; Varouchas, D.; Vartapetian, A.; Varvell, K. E.; Vasquez, J. G.; Vasquez, G. A.; Vazeille, F.; Vazquez Schroeder, T.; Veatch, J.; Veeraraghavan, V.; Veloce, L. M.; Veloso, F.; Veneziano, S.; Ventura, A.; Venturi, M.; Venturi, N.; Venturini, A.; Vercesi, V.; Verducci, M.; Verkerke, W.; Vermeulen, A. T.; Vermeulen, J. C.; Vetterli, M. C.; Viaux Maira, N.; Viazlo, O.; Vichou, I.; Vickey, T.; Vickey Boeriu, O. E.; Viehhauser, G. H. A.; Viel, S.; Vigani, L.; Villa, M.; Villaplana Perez, M.; Vilucchi, E.; Vincter, M. G.; Vinogradov, V. B.; Vishwakarma, A.; Vittori, C.; Vivarelli, I.; Vlachos, S.; Vogel, M.; Vokac, P.; Volpi, G.; von der Schmitt, H.; von Toerne, E.; Vorobel, V.; Vorobev, K.; Vos, M.; Voss, R.; Vossebeld, J. H.; Vranjes, N.; Vranjes Milosavljevic, M.; Vrba, V.; Vreeswijk, M.; Vuillermet, R.; Vukotic, I.; Wagner, P.; Wagner, W.; Wagner-Kuhr, J.; Wahlberg, H.; Wahrmund, S.; Wakabayashi, J.; Walder, J.; Walker, R.; Walkowiak, W.; Wallangen, V.; Wang, C.; Wang, C.; Wang, F.; Wang, H.; Wang, H.; Wang, J.; Wang, J.; Wang, Q.; Wang, R.; Wang, S. M.; Wang, T.; Wang, W.; Wang, W.; Wang, Z.; Wanotayaroj, C.; Warburton, A.; Ward, C. P.; Wardrope, D. R.; Washbrook, A.; Watkins, P. M.; Watson, A. T.; Watson, M. F.; Watts, G.; Watts, S.; Waugh, B. M.; Webb, A. F.; Webb, S.; Weber, M. S.; Weber, S. W.; Weber, S. A.; Webster, J. S.; Weidberg, A. R.; Weinert, B.; Weingarten, J.; Weirich, M.; Weiser, C.; Weits, H.; Wells, P. S.; Wenaus, T.; Wengler, T.; Wenig, S.; Wermes, N.; Werner, M. D.; Werner, P.; Wessels, M.; Weston, T. D.; Whalen, K.; Whallon, N. L.; Wharton, A. M.; White, A. S.; White, A.; White, M. J.; White, R.; Whiteson, D.; Whitmore, B. W.; Wickens, F. J.; Wiedenmann, W.; Wielers, M.; Wiglesworth, C.; Wiik-Fuchs, L. A. M.; Wildauer, A.; Wilk, F.; Wilkens, H. G.; Williams, H. H.; Williams, S.; Willis, C.; Willocq, S.; Wilson, J. A.; Wingerter-Seez, I.; Winkels, E.; Winklmeier, F.; Winston, O. J.; Winter, B. T.; Wittgen, M.; Wobisch, M.; Wolf, T. M. H.; Wolff, R.; Wolter, M. W.; Wolters, H.; Wong, V. W. S.; Worm, S. D.; Wosiek, B. K.; Wotschack, J.; Wozniak, K. W.; Wu, M.; Wu, S. L.; Wu, X.; Wu, Y.; Wyatt, T. R.; Wynne, B. M.; Xella, S.; Xi, Z.; Xia, L.; Xu, D.; Xu, L.; Xu, T.; Yabsley, B.; Yacoob, S.; Yamaguchi, D.; Yamaguchi, Y.; Yamamoto, A.; Yamamoto, S.; Yamanaka, T.; Yamatani, M.; Yamauchi, K.; Yamazaki, Y.; Yan, Z.; Yang, H.; Yang, H.; Yang, Y.; Yang, Z.; Yao, W.-M.; Yap, Y. C.; Yasu, Y.; Yatsenko, E.; Yau Wong, K. H.; Ye, J.; Ye, S.; Yeletskikh, I.; Yigitbasi, E.; Yildirim, E.; Yorita, K.; Yoshihara, K.; Young, C.; Young, C. J. S.; Yu, J.; Yu, J.; Yuen, S. P. Y.; Yusuff, I.; Zabinski, B.; Zacharis, G.; Zaidan, R.; Zaitsev, A. M.; Zakharchuk, N.; Zalieckas, J.; Zaman, A.; Zambito, S.; Zanzi, D.; Zeitnitz, C.; Zemaityte, G.; Zemla, A.; Zeng, J. C.; Zeng, Q.; Zenin, O.; Ženiš, T.; Zerwas, D.; Zhang, D.; Zhang, F.; Zhang, G.; Zhang, H.; Zhang, J.; Zhang, L.; Zhang, L.; Zhang, M.; Zhang, P.; Zhang, R.; Zhang, R.; Zhang, X.; Zhang, Y.; Zhang, Z.; Zhao, X.; Zhao, Y.; Zhao, Z.; Zhemchugov, A.; Zhou, B.; Zhou, C.; Zhou, L.; Zhou, M.; Zhou, M.; Zhou, N.; Zhu, C. G.; Zhu, H.; Zhu, J.; Zhu, Y.; Zhuang, X.; Zhukov, K.; Zibell, A.; Zieminska, D.; Zimine, N. I.; Zimmermann, C.; Zimmermann, S.; Zinonos, Z.; Zinser, M.; Ziolkowski, M.; Živković, L.; Zobernig, G.; Zoccoli, A.; Zou, R.; zur Nedden, M.; Zwalinski, L.

2017-10-01

A search is conducted for new resonant and non-resonant high-mass phenomena in dielectron and dimuon final states. The search uses 36.1 fb-1 of proton-proton collision data, collected at √{s}=13 TeV by the ATLAS experiment at the LHC in 2015 and 2016. No significant deviation from the Standard Model prediction is observed. Upper limits at 95% credibility level are set on the cross-section times branching ratio for resonances decaying into dileptons, which are converted to lower limits on the resonance mass, up to 4.1 TeV for the E6-motivated Z χ ' . Lower limits on the qqℓℓ contact interaction scale are set between 2.4 TeV and 40 TeV, depending on the model. [Figure not available: see fulltext.

Search for new high-mass phenomena in the dilepton final state using 36 fb –1 of proton-proton collision data at $$ \\sqrt{s}=13 $$ TeV with the ATLAS detector

DOE PAGES

Aaboud, M.; Aad, G.; Abbott, B.; ...

2017-10-26

A search is conducted for new resonant and non-resonant high-mass phenomena in dielectron and dimuon final states. The search uses 36.1 fb –1 of proton-proton collision data, collected at √s=13 TeV by the ATLAS experiment at the LHC in 2015 and 2016. No significant deviation from the Standard Model prediction is observed. Upper limits at 95% credibility level are set on the cross-section times branching ratio for resonances decaying into dileptons, which are converted to lower limits on the resonance mass, up to 4.1 TeV for the E6-motivated Z χ'. As a result, lower limits on the qqℓℓ contact interactionmore » scale are set between 2.4 TeV and 40 TeV, depending on the model.« less

Challenging the standard model by high-precision comparisons of the fundamental properties of protons and antiprotons

NASA Astrophysics Data System (ADS)

Ulmer, S.; Mooser, A.; Nagahama, H.; Sellner, S.; Smorra, C.

2018-03-01

The BASE collaboration investigates the fundamental properties of protons and antiprotons, such as charge-to-mass ratios and magnetic moments, using advanced cryogenic Penning trap systems. In recent years, we performed the most precise measurement of the magnetic moments of both the proton and the antiproton, and conducted the most precise comparison of the proton-to-antiproton charge-to-mass ratio. In addition, we have set the most stringent constraint on directly measured antiproton lifetime, based on a unique reservoir trap technique. Our matter/antimatter comparison experiments provide stringent tests of the fundamental charge-parity-time invariance, which is one of the fundamental symmetries of the standard model of particle physics. This article reviews the recent achievements of BASE and gives an outlook to our physics programme in the ELENA era. This article is part of the Theo Murphy meeting issue `Antiproton physics in the ELENA era'.

Pseudo-diode based on protonic/electronic hybrid oxide transistor

NASA Astrophysics Data System (ADS)

Fu, Yang Ming; Liu, Yang Hui; Zhu, Li Qiang; Xiao, Hui; Song, An Ran

2018-01-01

Current rectification behavior has been proved to be essential in modern electronics. Here, a pseudo-diode is proposed based on protonic/electronic hybrid indium-gallium-zinc oxide electric-double-layer (EDL) transistor. The oxide EDL transistors are fabricated by using phosphorous silicate glass (PSG) based proton conducting electrolyte as gate dielectric. A diode operation mode is established on the transistor, originating from field configurable proton fluxes within the PSG electrolyte. Current rectification ratios have been modulated to values ranged between ˜4 and ˜50 000 with gate electrode biased at voltages ranged between -0.7 V and 0.1 V. Interestingly, the proposed pseudo-diode also exhibits field reconfigurable threshold voltages. When the gate is biased at -0.5 V and 0.3 V, threshold voltages are set to ˜-1.3 V and -0.55 V, respectively. The proposed pseudo-diode may find potential applications in brain-inspired platforms and low-power portable systems.

Challenging the standard model by high-precision comparisons of the fundamental properties of protons and antiprotons.

PubMed

Ulmer, S; Mooser, A; Nagahama, H; Sellner, S; Smorra, C

2018-03-28

The BASE collaboration investigates the fundamental properties of protons and antiprotons, such as charge-to-mass ratios and magnetic moments, using advanced cryogenic Penning trap systems. In recent years, we performed the most precise measurement of the magnetic moments of both the proton and the antiproton, and conducted the most precise comparison of the proton-to-antiproton charge-to-mass ratio. In addition, we have set the most stringent constraint on directly measured antiproton lifetime, based on a unique reservoir trap technique. Our matter/antimatter comparison experiments provide stringent tests of the fundamental charge-parity-time invariance, which is one of the fundamental symmetries of the standard model of particle physics. This article reviews the recent achievements of BASE and gives an outlook to our physics programme in the ELENA era.This article is part of the Theo Murphy meeting issue 'Antiproton physics in the ELENA era'. © 2018 The Authors.

5 MeV Proton irradiation effects on 200 GHz silicon-germanium heterojunction bipolar transistors

NASA Astrophysics Data System (ADS)

Gnana Prakash, A. P.; Hegde, Vinayakprasanna N.; Pradeep, T. M.; Pushpa, N.; Bajpai, P. K.; Patel, S. P.; Trivedi, Tarkeshwar; Cressler, J. D.

2017-12-01

The total dose effects of 5 MeV proton and Co-60 gamma irradiation in the dose range from 1 to 100 Mrad on advanced 200 GHz Silicon-Germanium heterojunction bipolar transistors (SiGe HBTs) are investigated. The SRIM simulation study was conducted to understand the energy loss of 5 MeV proton ions in SiGe HBT structure. Pre- and post-radiation DC figure of merits such as forward- and inverse-mode Gummel characteristics, excess base current, DC current gain and output characteristics were used to quantify the radiation tolerance of the devices. The results show that the proton creates a significant amount of damages in the surface and bulk of the transistor when compared with gamma irradiation. The SiGe HBTs shows robust ionizing radiation tolerance even up to a total dose of 100 Mrad for both radiations.

Challenging the standard model by high-precision comparisons of the fundamental properties of protons and antiprotons

PubMed Central

Mooser, A.; Nagahama, H.; Sellner, S.; Smorra, C.

2018-01-01

The BASE collaboration investigates the fundamental properties of protons and antiprotons, such as charge-to-mass ratios and magnetic moments, using advanced cryogenic Penning trap systems. In recent years, we performed the most precise measurement of the magnetic moments of both the proton and the antiproton, and conducted the most precise comparison of the proton-to-antiproton charge-to-mass ratio. In addition, we have set the most stringent constraint on directly measured antiproton lifetime, based on a unique reservoir trap technique. Our matter/antimatter comparison experiments provide stringent tests of the fundamental charge–parity–time invariance, which is one of the fundamental symmetries of the standard model of particle physics. This article reviews the recent achievements of BASE and gives an outlook to our physics programme in the ELENA era. This article is part of the Theo Murphy meeting issue ‘Antiproton physics in the ELENA era’. PMID:29459414

Biodegradation test of SPS-LS blends as polymer electrolyte membrane fuel cells

NASA Astrophysics Data System (ADS)

Putri, Zufira; Arcana, I. Made

2014-03-01

Sulfonated polystyrene (SPS) can be applied as a proton exchange membrane fuel cell due to its fairly good chemical stability. In order to be applied as polymer electrolyte membrane fuel cells (PEMFCs), membrane polymer should have a good ionic conductivity, high proton conductivity, and high mechanical strength. Lignosulfonate (LS) is a complex biopolymer which has crosslinks and sulfonate groups. SPS-LS blends with addition of SiO2 are used to increase the proton conductivity and to improve the mechanical properties and thermal stability. However, the biodegradation test of SPS-LS blends is required to determine whether the application of these membranes to be applied as an environmentally friendly membrane. In this study, had been done the synthesis of SPS, biodegradability test of SPS-LS blends with variations of LS and SiO2 compositions. The biodegradation test was carried out in solid medium of Luria Bertani (LB) with an activated sludge used as a source of microorganism at incubation temperature of 37°C. Based on the results obtained indicated that SPS-LS-SiO2 blends are more decomposed by microorganism than SPS-LS blends. This result is supported by analysis of weight reduction percentage, functional groups with Fourier Transform Infrared (FTIR) Spectroscopy, and morphological surface with Scanning Electron Microscopy (SEM).

Electric double-layer capacitor based on an ionic clathrate hydrate.

PubMed

Lee, Wonhee; Kwon, Minchul; Park, Seongmin; Lim, Dongwook; Cha, Jong-Ho; Lee, Huen

2013-07-01

Herein, we suggest a new approach to an electric double-layer capacitor (EDLC) that is based on a proton-conducting ionic clathrate hydrate (ICH). The ice-like structures of clathrate hydrates, which are comprised of host water molecules and guest ions, make them suitable for applications in EDLC electrolytes, owing to their high proton conductivities and thermal stabilities. The carbon materials in the ICH Me4NOH⋅5 H2O show a high specific capacitance, reversible charge-discharge behavior, and a long cycle life. The ionic-hydrate complex provides the following advantages in comparison with conventional aqueous and polymer electrolytes: 1) The ICH does not cause leakage problems under normal EDLC operating conditions. 2) The hydrate material can be utilized itself, without requiring any pre-treatments or activation for proton conduction, thus shortening the preparation procedure of the EDLC. 3) The crystallization of the ICH makes it possible to tailor practical EDLC dimensions because of its fluidity as a liquid hydrate. 4) The hydrate solid electrolyte exhibits more-favorable electrochemical stability than aqueous and polymer electrolytes. Therefore, ICH materials are expected to find practical applications in versatile energy devices that incorporate electrochemical systems. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Designing a protonic ceramic fuel cell with novel electrochemically active oxygen electrodes based on doped Nd0.5Ba0.5FeO3-δ.

PubMed

Lyagaeva, Julia; Danilov, Nilolay; Tarutin, Arthem; Vdovin, Gennady; Medvedev, Dmitry; Demin, Anatoly; Tsiakaras, Panagiotis

2018-06-19

The Fe-based perovskite-structured Nd0.5Ba0.5FeO3-δ (NBF) system represents the basis for developing promising electrode materials for solid oxide fuel cells with proton-conducting electrolytes. This study aims at investigating the strategy of slight doping of neodymium-barium ferrite with some transition metals (M = Ni, Cu, Co) and examining the effect of this doping on the functional characteristics, such as phase structure, thermal expansion, total and ionic conductivity as well as electrochemical behavior, of Nd0.5Ba0.5Fe0.9M0.1O3-δ (NBFM) under testing in symmetrical cell (SC) and fuel cell (FC) modes of operation. Among the investigated dopants, cobalt (Co) is found to be the optimal dopant, resulting in an enhancement of transport properties and avoiding an undesirable increase in the thermal expansion coefficient. As a result, the electrode material made of NBFCo exhibits highest ionic conductivity and lowest polarization resistance in the SC mode of operation. Electrochemical characterization of the NBFCo cathode material in a protonic ceramic fuel cell (PCFC) followed by comparison of the obtained results with literature data demonstrates that NBFCo is an attractive cathode candidate for PCFC applications.

Evaluating the potential impact of proton carriers on syntrophic propionate oxidation

NASA Astrophysics Data System (ADS)

Juste-Poinapen, Natacha M. S.; Turner, Mark S.; Rabaey, Korneel; Virdis, Bernardino; Batstone, Damien J.

2015-12-01

Anaerobic propionic acid degradation relies on interspecies electron transfer (IET) between propionate oxidisers and electron acceptor microorganisms, via either molecular hydrogen, formate or direct transfers. We evaluated the possibility of stimulating direct IET, hence enhancing propionate oxidation, by increasing availability of proton carriers to decrease solution resistance and reduce pH gradients. Phosphate was used as a proton carrying anion, and chloride as control ion together with potassium as counter ion. Propionic acid consumption in anaerobic granules was assessed in a square factorial design with ratios (1:0, 2:1, 1:1, 1:2 and 0:1) of total phosphate (TP) to Cl-, at 1X, 10X, and 30X native conductivity (1.5 mS.cm-1). Maximum specific uptake rate, half saturation, and time delay were estimated using model-based analysis. Community profiles were analysed by fluorescent in situ hybridisation and 16S rRNA gene pyrosequencing. The strongest performance was at balanced (1:1) ratios at 10X conductivity where presumptive propionate oxidisers namely Syntrophobacter and Candidatus Cloacamonas were more abundant. There was a shift from Methanobacteriales at high phosphate, to Methanosaeta at low TP:Cl ratios and low conductivity. A lack of response to TP, and low percentage of presumptive electroactive organisms suggested that DIET was not favoured under the current experimental conditions.

A novel crosslinking strategy for preparing poly(vinyl alcohol)-based proton-conducting membranes with high sulfonation

NASA Astrophysics Data System (ADS)

Tsai, Chun-En; Lin, Chi-Wen; Hwang, Bing-Joe

This study synthesizes poly(vinyl alcohol) (PVA)-based polymer electrolyte membranes by a two-step crosslinking process involving esterization and acetal ring formation reactions. This work also uses sulfosuccinic acid (SSA) as the first crosslinking agent to form an inter-crosslinked structure and a promoting sulfonating agent. Glutaraldehyde (GA) as the second crosslinking agent, reacts with the spare OH group of PVA and forms, not only a dense structure at the outer membrane surface, but also a hydrophobic protective layer. Compared with membranes prepared by a traditional one-step crosslinking process, membranes prepared by the two-step crosslinking process exhibit excellent dissolution resistance in water. The membranes become water-insoluble even at a molar ratio of SO 3H/PVA-OH as high as 0.45. Moreover, the synthesized membranes also exhibit high proton conductivities and high methanol permeability resistance. The current study measures highest proton conductivity of 5.3 × 10 -2 S cm -1 at room temperature from one of the synthesized membranes, higher than that of the Nafion ® membrane. Methanol permeability of the synthesized membranes measures about 1 × 10 -7 cm 2 S -1, about one order of magnitude lower than that of the Nafion ® membrane.

Nafion/silane nanocomposite membranes for high temperature polymer electrolyte membrane fuel cell.

PubMed

Ghi, Lee Jin; Park, Na Ri; Kim, Moon Sung; Rhee, Hee Woo

2011-07-01

The polymer electrolyte membrane fuel cell (PEMFC) has been studied actively for both potable and stationary applications because it can offer high power density and be used only hydrogen and oxygen as environment-friendly fuels. Nafion which is widely used has mechanical and chemical stabilities as well as high conductivity. However, there is a drawback that it can be useless at high temperatures (> or = 90 degrees C) because proton conducting mechanism cannot work above 100 degrees C due to dehydration of membrane. Therefore, PEMFC should be operated for long-term at high temperatures continuously. In this study, we developed nanocomposite membrane using stable properties of Nafion and phosphonic acid groups which made proton conducting mechanism without water. 3-Aminopropyl triethoxysilane (APTES) was used to replace sulfonic acid groups of Nafion and then its aminopropyl group was chemically modified to phosphonic acid groups. The nanocomposite membrane showed very high conductivity (approximately 0.02 S/cm at 110 degrees C, <30% RH).

New synthesis of nanopowders of proton conducting materials. A route to densified proton ceramics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khani, Zohreh; Taillades-Jacquin, Melanie; Taillades, Gilles

2009-04-15

Low temperature routes have been developed for the preparation of BaCe{sub 0.9}Y{sub 0.1}O{sub 2.95} (BCY10) and BaZr{sub 0.9}Y{sub 0.1}O{sub 2.95} (BZY10) in the form of nanoparticulate powders for use after densification as ceramic membranes for a proton ceramic fuel cell. These methods make use on the one hand of the chelation of metal (II), (III) and (IV) ions by acrylates (hydrogelation route) and on the other of the destabilisation and precipitation of micro-emulsions. Both routes lead to single phase yttrium doped barium cerate or zirconate perovskites, as observed by X-ray diffraction, after thermal treatment at 900 deg. C for 4more » h for BCY10 and 800 deg. C for BZY10. These temperatures, lower than those usually used for preparation of barium cerate or zirconate, lead to oxide nanoparticles of size <40 nm. Dense ceramics (>=95%) are obtained by sintering BCY10 pellets at 1350 deg. C and BZY10 pellets at 1500 deg. C for 10 h. The water uptake of compacted samples at 500 deg. C is 0.14 wt% for BCY10 and 0.26 wt% for BZY10. Total conductivities in the range 300-600 deg. C were determined using impedance spectroscopy in a humidified nitrogen atmosphere. The total conductivity was 1.8x10{sup -2} S/cm for BCY10 and 2x10{sup -3} S/cm for BZY10 at 600 deg. C. The smallest perovskite nanoparticles and highest conductivities were obtained by hydrogelation of precursor barium, zirconium, cerium and yttrium acrylates. - Graphical Abstract: Low temperature hydrogelation and micro-emulsion routes have been developed for the preparation of rare earth doped barium and zirconium cerates in the form of nanoparticulate powders for use after densification as ceramic membranes for a proton ceramic fuel cell.« less

Spatial distributions of dose enhancement around a gold nanoparticle at several depths of proton Bragg peak

NASA Astrophysics Data System (ADS)

Kwon, Jihun; Sutherland, Kenneth; Hashimoto, Takayuki; Shirato, Hiroki; Date, Hiroyuki

2016-10-01

Gold nanoparticles (GNPs) have been recognized as a promising candidate for a radiation sensitizer. A proton beam incident on a GNP can produce secondary electrons, resulting in an enhancement of the dose around the GNP. However, little is known about the spatial distribution of dose enhancement around the GNP, especially in the direction along the incident proton. The purpose of this study is to determine the spatial distribution of dose enhancement by taking the incident direction into account. Two steps of calculation were conducted using the Geant4 Monte Carlo simulation toolkit. First, the energy spectra of 100 and 195 MeV protons colliding with a GNP were calculated at the Bragg peak and three other depths around the peak in liquid water. Second, the GNP was bombarded by protons with the obtained energy spectra. Radial dose distributions were computed along the incident beam direction. The spatial distributions of the dose enhancement factor (DEF) and subtracted dose (Dsub) were then evaluated. The spatial DEF distributions showed hot spots in the distal radial region from the proton beam axis. The spatial Dsub distribution isotropically spread out around the GNP. Low energy protons caused higher and wider dose enhancement. The macroscopic dose enhancement in clinical applications was also evaluated. The results suggest that the consideration of the spatial distribution of GNPs in treatment planning will maximize the potential of GNPs.

Thermal conductivity measurements of proton-heated warm dense aluminum

DOE PAGES

McKelvey, A.; Kemp, G. E.; Sterne, P. A.; ...

2017-08-01

Thermal conductivity is one of the most crucial physical properties of matter when it comes to understanding heat transport, hydrodynamic evolution, and energy balance in systems ranging from astrophysical objects to fusion plasmas. In the warm dense matter regime, experimental data are very scarce so that many theoretical models remain untested. Here we present the first thermal conductivity measurements of aluminum at 0.5–2.7 g/cc and 2–10 eV, using a recently developed platform of differential heating. A temperature gradient is induced in a Au/Al dual-layer target by proton heating, and subsequent heat flow from the hotter Au to the Al rearmore » surface is detected by two simultaneous time-resolved diagnostics. A systematic data set allows for constraining both thermal conductivity and equation-of-state models. Simulations using Purgatorio model or Sesame S27314 for Al thermal conductivity and LEOS for Au/Al release equation-of-state show good agreement with data after 15 ps. Discrepancy still exists at early time 0–15 ps, likely due to non-equilibrium conditions.« less

Thermal conductivity measurements of proton-heated warm dense aluminum

DOE Office of Scientific and Technical Information (OSTI.GOV)

McKelvey, A.; Kemp, G. E.; Sterne, P. A.

Thermal conductivity is one of the most crucial physical properties of matter when it comes to understanding heat transport, hydrodynamic evolution, and energy balance in systems ranging from astrophysical objects to fusion plasmas. In the warm dense matter regime, experimental data are very scarce so that many theoretical models remain untested. Here we present the first thermal conductivity measurements of aluminum at 0.5–2.7 g/cc and 2–10 eV, using a recently developed platform of differential heating. A temperature gradient is induced in a Au/Al dual-layer target by proton heating, and subsequent heat flow from the hotter Au to the Al rearmore » surface is detected by two simultaneous time-resolved diagnostics. A systematic data set allows for constraining both thermal conductivity and equation-of-state models. Simulations using Purgatorio model or Sesame S27314 for Al thermal conductivity and LEOS for Au/Al release equation-of-state show good agreement with data after 15 ps. Discrepancy still exists at early time 0–15 ps, likely due to non-equilibrium conditions.« less

Electrodeposition of Copper onto Polypyrrole Films: Application to Proton Reduction

NASA Astrophysics Data System (ADS)

Chikouche, Imene; Sahari, Ali; Zouaoui, Ahmed; Zegadi, Ameur

2016-09-01

In this paper, we have electrodeposited copper on polypyrrole surface. Results show that at high applied cathodic potential (>-1.8V), copper electrodeposition occurs with difficulties. The amount of electrodeposited copper is low (1.32%) and it is limited by the low polypyrrole conductivity. At this potential, poor conductivity is caused by its insulating state. However, at an applied cathodic potential of -1.2V, the polypyrrole exhibits a relatively high conductivity and copper particles are electrodeposited with large amounts (12.44%) on polypyrrole/silicon system. At high applied cathodic potential, the SEM images show clearly dispersed grains of copper, but polypyrrole surface is less occupied. At an applied cathodic potential of -1.2V, the SEM image shows that polypyrrole surface is homogenously more occupied with copper. After copper deposition, the Cu/PPy/Si system is used to catalyze the hydrogen reaction. It was found that, once the deposited copper is present with considerable amounts, the proton reduction occurs easily. As for the polypyrrole conductivity, it was found that electrodeposited copper onto PPy/Si surface affect the total conductivity.

Improved Anode for a Direct Methanol Fuel Cell

NASA Technical Reports Server (NTRS)

Valdez, Thomas; Narayanan, Sekharipuram

2005-01-01

A modified chemical composition has been devised to improve the performance of the anode of a direct methanol fuel cell. The main feature of the modified composition is the incorporation of hydrous ruthenium oxide into the anode structure. This modification can reduce the internal electrical resistance of the cell and increase the degree of utilization of the anode catalyst. As a result, a higher anode current density can be sustained with a smaller amount of anode catalyst. These improvements can translate into a smaller fuel-cell system and higher efficiency of conversion. Some background information is helpful for understanding the benefit afforded by the addition of hydrous ruthenium oxide. The anode of a direct methanol fuel cell sustains the electro-oxidation of methanol to carbon dioxide in the reaction CH3OH + H2O--->CO2 + 6H(+) + 6e(-). An electrocatalyst is needed to enable this reaction to occur. The catalyst that offers the highest activity is an alloy of approximately equal numbers of atoms of the noble metals platinum and ruthenium. The anode is made of a composite material that includes high-surface-area Pt/Ru alloy particles and a proton-conducting ionomeric material. This composite is usually deposited onto a polymer-electrolyte (proton-conducting) membrane and onto an anode gas-diffusion/current-collector sheet that is subsequently bonded to the proton-conducting membrane by hot pressing. Heretofore, the areal density of noble-metal catalyst typically needed for high performance has been about 8 mg/cm2. However, not all of the catalyst has been utilized in the catalyzed electro-oxidation reaction. Increasing the degree of utilization of the catalyst would make it possible to improve the performance of the cell for a given catalyst loading and/or reduce the catalyst loading (thereby reducing the cost of the cell). The use of carbon and possibly other electronic conductors in the catalyst layer has been proposed for increasing the utilization of the catalyst by increasing electrical connectivity between catalyst particles. However, the relatively low density of carbon results in thick catalyst layers that impede the mass transport of methanol to the catalytic sites. Also, the electrical conductivity of carbon is less than 1/300th of typical metals. Furthermore, the polymer-electrolyte membrane material is acidic and most metals are not chemically stable in contact with it. Finally, a material that conducts electrons (but not protons) does not contribute to the needed transport of protons produced in the electro-oxidation reaction.

Protonic/electronic hybrid oxide transistor gated by chitosan and its full-swing low voltage inverter applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chao, Jin Yu; Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201; Zhu, Li Qiang, E-mail: lqzhu@nimte.ac.cn

Modulation of charge carrier density in condensed materials based on ionic/electronic interaction has attracted much attention. Here, protonic/electronic hybrid indium-zinc-oxide (IZO) transistors gated by chitosan based electrolyte were obtained. The chitosan-based electrolyte illustrates a high proton conductivity and an extremely strong proton gating behavior. The transistor illustrates good electrical performances at a low operating voltage of ∼1.0 V such as on/off ratio of ∼3 × 10{sup 7}, subthreshold swing of ∼65 mV/dec, threshold voltage of ∼0.3 V, and mobility of ∼7 cm{sup 2}/V s. Good positive gate bias stress stabilities are obtained. Furthermore, a low voltage driven resistor-loaded inverter was built by using an IZO transistor inmore » series with a load resistor, exhibiting a linear relationship between the voltage gain and the supplied voltage. The inverter is also used for decreasing noises of input signals. The protonic/electronic hybrid IZO transistors have potential applications in biochemical sensors and portable electronics.« less

Probing short-range correlations in asymmetric nuclei with quasi-free pair knockout reactions

NASA Astrophysics Data System (ADS)

Stevens, Sam; Ryckebusch, Jan; Cosyn, Wim; Waets, Andreas

2018-02-01

Short-range correlations (SRC) in asymmetric nuclei with an unusual neutron-to-proton ratio can be studied with quasi-free two-nucleon knockout processes following the collision between accelerated ions and a proton target. We derive an approximate factorized cross section for those SRC-driven p (A ,p‧N1N2) reactions. Our reaction model hinges on the factorization properties of SRC-driven A (e ,e‧N1N2) reactions for which strong indications are found in theory-experiment comparisons. In order to put our model to the test we compare its predictions with results of 12C (p ,p‧ pn) measurements conducted at Brookhaven National Laboratory (BNL) and find a fair agreement. The model can also reproduce characteristic features of SRC-driven two-nucleon knockout reactions, like back-to-back emission of the correlated nucleons. We study the asymmetry dependence of nuclear SRC by providing predictions for the ratio of proton-proton to proton-neutron knockout cross sections for the carbon isotopes 9-15C thereby covering neutron excess values (N - Z) / Z between -0.5 and +0.5.

Electronic state and optical response in a hydrogen-bonded molecular conductor

NASA Astrophysics Data System (ADS)

Naka, Makoto; Ishihara, Sumio

2018-06-01

Motivated by recent experimental studies of hydrogen-bonded molecular conductors κ -X 3(Cat-EDT-TTF) 2[X =H , D], interplays of protons and correlated electrons, and their effects on magnetic, dielectric, and optical properties, are studied theoretically. We introduce a model Hamiltonian for κ -X 3(Cat-EDT-TTF) 2, in which molecular dimers are connected by hydrogen bonds. Ground-state phase diagram and optical conductivity spectra are examined by using the mean-field approximation and the exact diagonalization method in finite-size cluster. Three types of the competing electronic and protonic phases, charge density wave phase, polar charge-ordered phase, and antiferromagnetic dimer-Mott insulating phase are found. Observed softening of the interdimer excitation due to the electron-proton coupling implies reduction of the effective electron-electron repulsion, i.e., "Hubbard U ," due to the quantum proton motion. Contrastingly, the intradimer charge excitation is hardened due to the proton-electron coupling. Implications of the theoretical calculations to the recent experimental results in κ -X 3(Cat-EDT-TTF) 2 are discussed.

Effect of end-group cross-linking on transport properties of sulfonated poly(phenylene sulfide nitrile)s for proton exchange membranes

NASA Astrophysics Data System (ADS)

Kang, Na Rae; Lee, So Young; Shin, Dong Won; Hwang, Doo Sung; Lee, Kang Hyuck; Cho, Doo Hee; Kim, Ji Hoon; Lee, Young Moo

2016-03-01

A series of end-group cross-linked membranes (Az-XESPSN) were prepared by click reaction to investigate the effects of cross-linking on the morphology and proton transport properties of proton exchange membranes. The morphological transformations resulting from thermal annealing and cross-linking were observed by means of atomic force microscopy (AFM) and transmission electron microscopy (TEM). Compared to the non-cross-linked ESPSN membranes, the Az-XESPSN membranes exhibited lower water uptake and improved mechanical and chemical stabilities. In addition, the Az-XESPSN membranes exhibited higher proton conductivities (0.018-0.028 S cm-1) compared to those of the ESPSN membranes (0.0044-0.0053 S cm-1) and Nafion 212 (0.0061 S cm-1), particularly in conditions of elevated temperature (120 °C) and low relative humidity (35%). Such enhancements can be attributed to a synergistic effect of well-defined hydrophilic ionic clusters and triazole groups that function as proton carriers under anhydrous conditions. Furthermore, the Az-XESPSN membranes exhibited significantly enhanced single cell performance and long-term stability compared to those of ESPSN membranes.

Proton exchange membranes for application in fuel cells: grafted silica/SPEEK nanocomposite elaboration and characterization.

PubMed

Reinholdt, Marc X; Kaliaguine, Serge

2010-07-06

Hydrogen technologies and especially fuel cells are key components in the battle to find alternate sources of energy to the highly polluting and economically constraining fossil fuels in an aim to preserve the environment. The present paper shows the synthesis of surface functionalized silica nanoparticles, which are used to prepare grafted silica/SPEEK nanocomposite membranes. The nanoparticles are grafted either with hexadecylsilyl or aminopropyldimethylsilyl moieties or both. The synthesized particles are analyzed using XRD, NMR, TEM, and DLS to collect information on the nature of the particles and the functional groups, on the particle sizes, and on the hydrophilic/hydrophobic character. The composite membranes prepared using the synthesized particles and two SPEEK polymers with sulfonation degrees of 69.4% and 85.0% are characterized for their proton conductivity and water uptake properties. The corresponding curves are very similar for the composites prepared with both polymers and the nanoparticles bearing the two functional groups. The composites prepared with the nanoparticles bearing solely the aminopropyldimethylsilyl moiety exhibit lower conductivity and water uptake, possibly due to higher interaction of the polymer sulfonic acid sites with the amine groups. The composites prepared with the nanoparticles bearing solely the hexadecylsilyl moiety were not further investigated because of very high particles segregation. A study of the proton conductivity as a function of temperature was performed on selected membranes and showed that nanocomposites made with nanoparticles bearing both functional moieties have a higher conductivity at higher temperatures.

Ionic Liquids and New Proton Exchange Membranes for Fuel Cells

NASA Technical Reports Server (NTRS)

Belieres, Jean-Philippe

2004-01-01

There is currently a great surge of activity in fuel cell research as laboratories across the world seek to take advantage of the high energy capacity provided by &el cells relative to those of other portable electrochemical power systems. Much of this activity is aimed at high temperature fie1 cells, and a vital component of such &el cells must be the availability of a high temperature stable proton-permeable membrane. NASA Glenn Research Center is greatly involved in developing this technology. Other approaches to the high temperature fuel cell involve the use of single- component or almost-single-component electrolytes that provide a path for protons through the cell. A heavily researched case is the phosphoric acid fuel cell, in which the electrolyte is almost pure phosphoric acid and the cathode reaction produces water directly. The phosphoric acid fie1 cell delivers an open circuit voltage of 0.9 V falling to about 0.7 V under operating conditions at 170 C. The proton transport mechanism is mainly vehicular in character according to the viscosity/conductance relation. Here we describe some Proton Transfer Ionic Liquids (PTILs) with low vapor pressure and high temperature stability that have conductivities of unprecedented magnitude for non-aqueous systems. The first requirement of an ionic liquid is that, contrary to experience with most liquids consisting of ions, it must have a melting point that is not much above room temperature. The limit commonly suggested is 100 C. PTILs constitute an interesting class of non-corrosive proton-exchange electrolyte, which can serve well in high temperature (T = 100 - 250 C) fuel cell applications. We will present cell performance data showing that the open circuit voltage output, and the performance of a simple H2(g)Pt/PTIL/Pt/O2(g) fuel cell may be superior to those of the equivalent phosphoric acid electrolyte fuel cell both at ambient temperature and temperatures up to and above 200 C. My work at NASA Glenn Research Center during this summer is to develop and characterize proton exchange membranes doped with ionic liquids. The main techniques used to characterize these materials are: Impedance Spectroscopy, NMR, DSC, TGA, DMA, IR, and SEM ...

Harvesting electricity from human hair.

PubMed

Tulachan, Brindan; Singh, Sushil K; Philip, Deepu; Das, Mainak

2016-01-01

Electrical conductivity of human hair is a debatable issue among hair experts and scientists. There are unsubstantiated claims that hair conducts electricity. However, hair experts provided ample evidence that hair is an insulator. Although wet hair exhibited drastic reduction in resistivity; scientists regarded hair as a proton semiconductor at the best. Here, we demonstrate that hair filaments generate electricity on absorbing water vapor between 50 degrees and 80 degrees C. This electricity can operate low power electronic systems. Essentially, we are exposing the hydrated hair polymer to a high temperature (50 degrees-80 degrees C). It has long been speculated that when certain biopolymers are simultaneously hydrated and exposed to high temperature, they exhibit significant proton hopping at a specific temperature regime. This happens due to rapid movement of water molecules on the polymer surface. This lead us to speculate that the observed flow of current is partly ionic and partly due to "proton hopping" in the hydrated nano spaces of hair filament. Such proton hopping is exceptionally high when the hydrated hair polymer is exposed to a temperature between 50 degrees and 80 degrees C. Differential scanning calorimetry data further corroborated the results and indicated that indeed at this temperature range, there is an enormous movement of water molecules on the hair polymer surface. This enormously rapid movement of water molecules lead to the "making and breaking" of innumerable hydrogen bonds and thus resulting in hopping of the protons. What is challenging is "how to tap these hopping protons to obtain useful electricity?" We achieved this by placing a bundle of hair between two different electrodes having different electro negativities, and exposing it to water vapor (water + heat). The two different electrodes offered directionality to the hopping protons and the existing ions and thus resulting in the generation of useful current. Further, by continuously hydrating the polymer with water vapor, we prolonged the process. If this interesting aspect of polymer is exploited further and fine tuned, then it will open new avenues for development of sophisticated polymer-based systems, which could be used to harvest electricity from waste heat.

Cost-effectiveness of histamine receptor-2 antagonist versus proton pump inhibitor for stress ulcer prophylaxis in critically ill patients*.

PubMed

MacLaren, Robert; Campbell, Jon

2014-04-01

To examine the cost-effectiveness of using histamine receptor-2 antagonist or proton pump inhibitor for stress ulcer prophylaxis. Decision analysis model examining costs and effectiveness of using histamine receptor-2 antagonist or proton pump inhibitor for stress ulcer prophylaxis. Costs were expressed in 2012 U.S. dollars from the perspective of the institution and included drug regimens and the following outcomes: clinically significant stress-related mucosal bleed, ventilator-associated pneumonia, and Clostridium difficile infection. Effectiveness was the mortality risk associated with these outcomes and represented by survival. Costs, occurrence rates, and mortality probabilities were extracted from published data. A simulation model. A mixed adult ICU population. Histamine receptor-2 antagonist or proton pump inhibitor for 9 days of stress ulcer prophylaxis therapy. Output variables were expected costs, expected survival rates, incremental cost, and incremental survival rate. Univariate sensitivity analyses were conducted to determine the drivers of incremental cost and incremental survival. Probabilistic sensitivity analysis was conducted using second-order Monte Carlo simulation. For the base case analysis, the expected cost of providing stress ulcer prophylaxis was $6,707 with histamine receptor-2 antagonist and $7,802 with proton pump inhibitor, resulting in a cost saving of $1,095 with histamine receptor-2 antagonist. The associated mortality probabilities were 3.819% and 3.825%, respectively, resulting in an absolute survival benefit of 0.006% with histamine receptor-2 antagonist. The primary drivers of incremental cost and survival were the assumptions surrounding ventilator-associated pneumonia and bleed. The probabilities that histamine receptor-2 antagonist was less costly and provided favorable survival were 89.4% and 55.7%, respectively. A secondary analysis assuming equal rates of C. difficile infection showed a cost saving of $908 with histamine receptor-2 antagonists, but the survival benefit of 0.0167% favored proton pump inhibitors. Histamine receptor-2 antagonist therapy appears to reduce costs with survival benefit comparable to proton pump inhibitor therapy for stress ulcer prophylaxis. Ventilator-associated pneumonia and bleed are the variables most affecting these outcomes. The uncertainty in the findings justifies a prospective trial.

Influence of water and membrane microstructure on the transport properties of proton exchange membrane fuel cells

NASA Astrophysics Data System (ADS)

Siu, Ana Rosa

Proton transport in proton exchange membranes (PEMs) depends on interaction between water and acid groups covalently bound to the polymer. Although the presence of water is important in maintaining the PEM's functions, a thorough understanding of this topic is still lacking. The objective of this work is to provide a better understanding of how the nature water, confined to ionic domains of the polymer, influences the membrane's ability to transport protons, methanol and water. Understanding this topic will facilitate development of new materials with favorable transport properties for fuel cells use. Five classes of polymer membranes were used in this work: polyacrylonitrile-graft-poly(styrenesulfonic) acid (PAN-g-macPSSA); poly(vinylidene difluoride) irradiation-graft-poly(styrenesulfonic) acid (PVDF-g-PSSA); poly(ethylenetetrafluoroethylene) irradiation-graft-poly(styrenesulfonic) acid (ETFE-gPSSA); PVDF-g-PSSA with hydroxyethylmethacrylate (HEMA); and perfluorosulfonic acid membrane (Nafion). The nature of water within the polymers (freezable versus non-freezable states) was measured by systematically freezing samples, and observing the temperature at which water freezes and the amount of heat released in the process. Freezing water-swollen membranes resulted in a 4-fold decrease in the proton conductivity of the PEM. Activation energies of proton transport before and after freezing were ˜ 0.15 eV and 0.5 eV, consistent with proton transport through liquid water and bound water, respectively. Reducing the content of water in membrane samples decreased the amount of freezable and non-freezable water. Calorimetric measurements of membranes in various degrees of hydration showed that water molecules became non-freezable when lambda, (water molecules per sulfonic acid group) was less than ˜14. Proton conduction through membranes containing only non-freezable water was demonstrated to be feasible. Diffusion experiments showed that the permeability of methanol decreased when the content of free water in the membranes decreased. Variation in permeability trends observed for the different polymer classes of the same content of free water was explained on the basis of tortuosity and interaction of methanol within the ionic network. Finally, a novel set of polymers containing non-ionic hydrophilic segments were examined for enhanced water transport in order to see if such domains might offset the flux of water due to electro-osmosis.

New insight into the properties of proton conducting oxides from neutron total scattering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Proffen, Thomas E; Kim, Hyunjeong; Malavasi, Lorenzo

In recent years there has been a growing interest in searching for new proton conducting materials that could be successfully used in medium temperature solid oxide fuel cells (SOFC). In particular, proton conducting oxides have been the subject of a massive research activity. Among the most promising oxide the acceptor doped cerates appears to be those most appealing in view of practical applications. A relevant aspect of these materials is the investigation of the local distortion of the structure arising from water incorporation. This kind of study is of great help in defining how the structure changes in order tomore » accommodate the proton which is usually thought to enter the structure in form of hydroxyl group where the oxygen vacancy results from the acceptor doping on the Ce site. Atomistic simulation work confirmed that the preferential location of dopant ions is on the Ce site. To the best of our knowledge the only experimental work addressing the role of dopant and water incorporation on the local structure of V-doped cerates is a X-ray absorption spectroscopy (XAS) work carried out by Longo and coworkers at the Y K-edge. The main conclusion of that work was the observation that Y-doping induces a distortion of the parent BaCe0{sub 3} structure resulting in a significantly distorted Y local environment. However, local structure information derived from XAS study does not provide a direct structural information and depends strongly upon the model used to calcualte theoretical {chi}(k) which is not unique. Moreover, the XAS analysis usually provide significant information only up to the second shell. As a consequence, a more reliable and useful technique to investigate the local arrangement in these proton conducting oxides appears to be the Pair Distribution Function (PDF) analysis derived from total neutron scattering measurements. In the present work we investigated the pure BaCeO{sub 3} and the acceptor doped BaCe{sub 0.90}Y{sub 0.10}O{sub 2.85} compounds. In both cases the samples have been measured at room temperature and after being exposed to dry and wet air (humidification attained through bubbling air in D{sub 2}O). Aim of this work is to look at the effect of Y-doping and water doping on the local structure of the above mentioned samples.« less

Enhanced Proton Conductivity of Sulfonated Hybrid Poly(arylene ether ketone) Membranes by Incorporating an Amino-Sulfo Bifunctionalized Metal-Organic Framework for Direct Methanol Fuel Cells.

PubMed

Ru, Chunyu; Li, Zhenhua; Zhao, Chengji; Duan, Yuting; Zhuang, Zhuang; Bu, Fanzhe; Na, Hui

2018-03-07

Novel side-chain-type sulfonated poly(arylene ether ketone) (SNF-PAEK) containing naphthalene and fluorine moieties on the main chain was prepared in this work, and a new amino-sulfo-bifunctionalized metal-organic framework (MNS, short for MIL-101-NH 2 -SO 3 H) was synthesized via a hydrothermal technology and postmodification. Then, MNS was incorporated into a SNF-PAEK matrix as an inorganic nanofiller to prepare a series of organic-inorganic hybrid membranes (MNS@SNF-PAEK-XX). The mechanical property, methanol resistance, electrochemistry, and other properties of MNS@SNF-PAEK-XX hybrid membranes were characterized in detail. We found that the mechanical strength and methanol resistances of these hybrid membranes were improved by the formation of an ionic cross-linking structure between -NH 2 of MNS and -SO 3 H on the side chain of SNF-PAEK. Particularly, the proton conductivity of these hybrid membranes increased obviously after the addition of MNS. MNS@SNF-PAEK-3% exhibited the proton conductivity of 0.192 S·cm -1 , which was much higher than those of the pristine membrane (0.145 S·cm -1 ) and recast Nafion (0.134 S·cm -1 ) at 80 °C. This result indicated that bifunctionalized MNS rearranged the microstructure of hybrid membranes, which could accelerate the transfer of protons. The hybrid membrane (MNS@SNF-PAEK-3%) showed a better direct methanol fuel cell performance with a higher peak power density of 125.7 mW/cm 2 at 80 °C and a higher open-circuit voltage (0.839 V) than the pristine membrane.

Microbial Activity Influences Electrical Conductivity of Biofilm Anode

EPA Science Inventory

This study assessed the conductivity of a Geobacter-enriched biofilm anode along with biofilm activity in a microbial electrochemical cell (MxC) equipped with two gold anodes (25 mM acetate medium), as different proton gradients were built throughout the biofilm. There was no pH ...

Dynamic Properties of the International Space Station throughout the Assembly Process

DTIC Science & Technology

1998-06-29

with the launch of the Russian-built FGB, or Functional Cargo Block (most fitting translation) atop a Russian Proton rocket in June of 1998. Phase Two...experiments were conducted in areas of plant growth, life sciences, and microgravity science. But more importantly, Mir-Shuttle operations presented...Configuration Rationale/Comments 30Jun 1998 1 A/R Russian Proton • Functional Cargo Block (FGB) • FGB is a self-supporting active vehicle. • It provides

TiO2/bi A-SPAES(Ds 1.0) composite membranes for proton exchange membrane in direct methanol fuel cell (DMFC).

PubMed

Zhang, Ni; Zhong, Chuanqing; Xie, Bing; Liu, Huiling; Wang, Xingzu

2014-09-01

A series of TiO2/bi A-SPAES(Ds 1.0) composite membranes with various contents of nano-sized TiO2 particles were prepared through sol-gel method. Scanning electron microscopy (SEM) images indicated the TiO2 particles were well dispersed within polymer matrix. These membranes were used for proton exchange membrane (PEM) for performance evaluation in direct methanol fuel cell (DMFC). These composite membranes showed good thermal stability and mechanical strength. It was found that the water uptake of these membranes enhanced with the TiO2 amount increasing in these composite membranes. Meanwhile, the introduction of TiO2 particles increased the proton conductivity and reduced the methanol permeability. The proton conductivities of these composite membranes with 8% TiO2 particles (0.120 S/cm and 0.128 S/cm) were higher than those of Nafion 117 membrane (0.114 S/cm and 0.117 S/cm) at 80 degrees C and 100 degrees C. Specially, the methanol diffusion coefficient (1.2 x 10(-7) cm2/s) of the composite membrane with 8% TiO2 content was much lower than that of Nafion 117 membrane (2.1 x 10(-6) cm2/s). As a result, the TiO2/bi A-SPAES composite membrane was considered as a promising material for PEM in DMFC.

Effects of nitrogen fertilization on the acidity and salinity of greenhouse soils.

PubMed

Han, Jiangpei; Shi, Jiachun; Zeng, Lingzao; Xu, Jianming; Wu, Laosheng

2015-02-01

A greenhouse pot experiment was conducted to study the effects of conventional nitrogen fertilization on soil acidity and salinity. Three N rates (urea; N0, 0 kg N ha(-1); N1, 600 kg N ha(-1); and N2, 1,200 kg N ha(-1)) were applied in five soils with different greenhouse cultivation years to evaluate soil acidification and salinization rate induced by nitrogen fertilizer in lettuce production. Both soil acidity and salinity increased significantly as N input increased after one season, with pH decrease ranging from 0.45 to 1.06 units and electrolytic conductivity increase from 0.24 to 0.68 mS cm(-1). An estimated 0.92 mol H(+) was produced for 1 mol (NO2 (-) + NO3 (-))-N accumulation in soil. The proton loading from nitrification was 14.3-27.3 and 12.1-58.2 kmol H(+) ha(-1) in the center of Shandong Province under N1 and N2 rate, respectively. However, the proton loading from the uptake of excess bases by lettuces was only 0.3-4.5 % of that from nitrification. Moreover, the release of protons induced the direct release of base cations and accelerated soil salinization. The increase of soil acidity and salinity was attributed to the nitrification of excess N fertilizer. Compared to the proton loading by lettuce, nitrification contributed more to soil acidification in greenhouse soils.

Electrostatic attraction of weak monoacid anions increases probability for protonation and passage through aquaporins.

PubMed

Rothert, Monja; Rönfeldt, Deike; Beitz, Eric

2017-06-02

A positive electrostatic field emanating from the center of the aquaporin (AQP) water and solute channel is responsible for the repulsion of cations. At the same time, however, a positive field will attract anions. In this regard, l-lactate/lactic acid permeability has been shown for various isoforms of the otherwise highly water and neutral substrate selective AQP family. The structural requirements rendering certain AQPs permeable for weak monoacids and the mechanism of conduction have remained unclear. Here, we show by profiling pH-dependent substrate permeability, measurements of media alkalization, and proton decoupling that AQP9 acts as a channel for the protonated, neutral monocarboxylic acid species. Intriguingly, the obtained permeability rates indicate an up to 10 times higher probability of passage via AQP9 than given by the fraction of the protonated acid substrate at a certain pH. We generated AQP9 point mutants showing that this effect is independent from properties of the channel interior but caused by the protein surface electrostatics. Monocarboxylic acid-conducting AQPs thus employ a mechanism similar to the family of formate-nitrite transporters for weak monoacids. On a more general basis, our data illustrate semiquantitatively the contribution of surface electrostatics to the interaction of charged molecule substrates or ligands with target proteins, such as channels, transporters, enzymes, or receptors. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Composite plasma polymerized sulfonated polystyrene membrane for PEMFC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nath, Bhabesh Kumar; Khan, Aziz; Chutia, Joyanti, E-mail: jchutiaiasst@gmail.com

2015-10-15

Highlights: • Methyl methane sulfonate (MMS) is used as the sulfonating agent. • The proton conductivity of the membrane is found to be 0.141 S cm{sup −1}. • Power density of fuel cell with styrene/MMS membrane is 0.5 W cm{sup −2}. • The membrane exhibits thermal stability up to 140 °C. - Abstract: This work presents the introduction of an organic compound methyl methane sulfonate (MMS) for the first time in fabrication of polystyrene based proton exchange membrane (PEM) by plasma polymerization process. The membrane is fabricated by co-polymerizing styrene and MMS in capacitively coupled continuous RF plasma. The chemicalmore » composition of the plasma polymerized polymer membrane is investigated using Fourier Transform Infrared Spectroscopy which reveals the formation of composite structure of styrene and MMS. The surface morphology studied using AFM and SEM depicts the effect of higher partial pressure of MMS on surface topography of the membrane. The proton transport property of the membrane studied using electrochemical impedance spectroscopy shows the achievement of maximum proton conductivity of 0.141 S cm{sup −1} which is comparable to Nafion 117 membrane. Fuel cell performance test of the synthesized membrane shows a maximum power density of 500 mW cm{sup −2} and current density of 0.62 A cm{sup −2} at 0.6 V.« less

Proton exchange membrane fuel cells for space and electric vehicle applications: From basic research to technology development

NASA Technical Reports Server (NTRS)

Srinivasan, Supramaniam; Mukerjee, Sanjeev; Parthasarathy, A.; CesarFerreira, A.; Wakizoe, Masanobu; Rho, Yong Woo; Kim, Junbom; Mosdale, Renaut A.; Paetzold, Ronald F.; Lee, James

1994-01-01

The proton exchange membrane fuel cell (PEMFC) is one of the most promising electrochemical power sources for space and electric vehicle applications. The wide spectrum of R&D activities on PEMFC's, carried out in our Center from 1988 to date, is as follows (1) Electrode Kinetic and Electrocatalysis of Oxygen Reduction; (2) Optimization of Structures of Electrodes and of Membrane and Electrode Assemblies; (3) Selection and Evaluation of Advanced Proton Conducting Membranes and of Operating Conditions to Attain High Energy Efficiency; (4) Modeling Analysis of Fuel Cell Performance and of Thermal and Water Management; and (5) Engineering Design and Development of Multicell Stacks. The accomplishments on these tasks may be summarized as follows: (1) A microelectrode technique was developed to determine the electrode kinetic parameters for the fuel cell reactions and mass transport parameters for the H2 and O2 reactants in the proton conducting membrane. (2) High energy efficiencies and high power densities were demonstrated in PEMFCs with low platinum loading electrodes (0.4 mg/cm(exp 2) or less), advanced membranes and optimized structures of membrane and electrode assemblies, as well as operating conditions. (3) The modeling analyses revealed methods to minimize mass transport limitations, particularly with air as the cathodic reactant; and for efficient thermal and water management. (4) Work is in progress to develop multi-kilowatt stacks with the electrodes containing low platinum loadings.

White light generation by carbonyl based indole derivatives due to proton transfer: an efficient fluorescence sensor.

PubMed

Singla, Nidhi; Bhadram, Venkata Srinu; Narayana, Chandrabhas; Chowdhury, Papia

2013-04-04

The motivation of the present work is to understand the optical, chemical, and electrical aspects of the proton transfer mechanism of indole (I) and some carbonyl based indole derivatives: indole-3-carboxaldehyde (I3C) and indole-7-carboxaldehyde (I7C) for both powder form and their liquid solution. Structural information for indole derivatives (isolated molecule and in solution) is obtained with density functional theory (DFT) and time dependent DFT (TD-DFT) methods. Calculated transition energies are used to generate UV-vis, FTIR, Raman, and NMR spectra which are later verified with the experimental spectra. The occurrence of different conformers [cis (N(c)), trans (N(t)), and zwitterion (Z*)] have been interpreted by Mulliken charge, natural bond orbital (NBO) analysis, and polarization versus electric field (P-E loop) studies. (1)H and (13)C NMR and molecular vibrational frequencies of the fundamental modes established the stability of Nc due to the presence of intramolecular hydrogen bonding (IHB) in the ground state (S0). Computed/experimental UV-vis absorption/emission studies reveal the creation of new species: zwitterion (Z*) and anion (A*) in the excited state (S1) due to excited state intramolecular and intermolecular proton transfer (ESI(ra)PT and ESI(er)PT). Increased electrical conductivity (σ(ac)) with temperature and increased ferroelectric polarization at higher field verifies proton conduction in I7C.

Nanocomposite membranes based on polybenzimidazole and ZrO2 for high-temperature proton exchange membrane fuel cells.

PubMed

Nawn, Graeme; Pace, Giuseppe; Lavina, Sandra; Vezzù, Keti; Negro, Enrico; Bertasi, Federico; Polizzi, Stefano; Di Noto, Vito

2015-04-24

Owing to the numerous benefits obtained when operating proton exchange membrane fuel cells at elevated temperature (>100 °C), the development of thermally stable proton exchange membranes that demonstrate conductivity under anhydrous conditions remains a significant goal for fuel cell technology. This paper presents composite membranes consisting of poly[2,2'-(m-phenylene)-5,5'-bibenzimidazole] (PBI4N) impregnated with a ZrO2 nanofiller of varying content (ranging from 0 to 22 wt %). The structure-property relationships of the acid-doped and undoped composite membranes have been studied using thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, wide-angle X-ray scattering, infrared spectroscopy, and broadband electrical spectroscopy. Results indicate that the level of nanofiller has a significant effect on the membrane properties. From 0 to 8 wt %, the acid uptake as well as the thermal and mechanical properties of the membrane increase. As the nanofiller level is increased from 8 to 22 wt % the opposite effect is observed. At 185 °C, the ionic conductivity of [PBI4N(ZrO2 )0.231 ](H3 PO4 )13 is found to be 1.04×10(-1)  S cm(-1) . This renders membranes of this type promising candidates for use in high-temperature proton exchange membrane fuel cells. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Alternative Electrochemical Systems for Ozonation of Water

NASA Technical Reports Server (NTRS)

Andrews, Craig C.; Murphy, Oliver J.

2003-01-01

Electrochemical systems that are especially well suited for the small-scale generation of ozone and ozonated water for local use have been invented. These systems can operate with very little maintenance, and the only inputs needed during operation are electric power and water. Ozonated water produced by these systems can be used in diverse industrial applications: A few examples include sterilization in the brewing industry, general disinfection, and treatment of sewage and recycled water. The basic principle of operation admits of several alternative system configurations. The heart of the system is a stack of electrolytic cells, each containing a proton-exchange membrane (which serves as a solid electrolyte) sandwiched between a catalytic anode and a catalytic cathode. Preferably, the proton-exchange membrane is made of a perfluorinated sulfonic acid polymer. During electrolysis, a mixture of O2 and O3 gases is generated at the anode and H2 is generated at the cathode. Some of the O3 generated at the anode becomes dissolved in the water. The proportion of O3 in the O2/O3 mixture can be maximized by the selection of suitable electrode materials and the use of a high overpotential. Although the proton-exchange membrane conducts protons, it does not conduct electrons. It is also impermeable by gases; consequently, it maintains separation between the O2/O3 mixture evolved at the anode and the H2 evolved at the cathode.

Proton exchange membrane based on chitosan and solvent-free carbon nanotube fluids for fuel cells applications.

PubMed

Wang, Jie; Gong, Chunli; Wen, Sheng; Liu, Hai; Qin, Caiqin; Xiong, Chuanxi; Dong, Lijie

2018-04-15

Poor dispersion and inert ionic conduction are two major obstacles towards using carbon nanotubes (CNTs) to modify polymer electrolyte membranes (PEMs) in energy conversion devices. In this work, solvent-free carbon nanotube fluids (CNT fluids) with liquid-like behavior are prepared through an ion exchange method and incorporated into a chitosan (CS) matrix to fabricate composite membranes. The electrostatic interactions between SO 3 - groups in the CNT fluids and NH 2 groups in the CS matrix, in addition to the unique flow properties of the CNT fluids, promote the uniform dispersion of CNT fluids in the CS matrix. Markedly, the CS/CNT fluid-3 composite membrane is simultaneously reinforced and toughened by 180% and 300% compared to pure CS membrane, respectively. Moreover, the SO 3 - groups in the CNT fluids facilitate the proton transfer such that the proton conductivity of CS/CNT fluid-3 composite membrane reaches a maximum value of 0.044 S cm -1 at 80 °C. Copyright © 2018 Elsevier Ltd. All rights reserved.

Solar Powered CO.Sub.2 Conversion

NASA Technical Reports Server (NTRS)

Chen, Bin (Inventor)

2016-01-01

Methods and devices for reducing CO.sub.2 to produce hydrocarbons are disclosed. A device comprises a photoanode capable of splitting H.sub.2O into electrons, protons, and oxygen; an electrochemical cell cathode comprising an electro-catalyst capable of reducing CO.sub.2; H.sub.2O in contact with the surface of the photoanode; CO.sub.2 in contact with the surface of the cathode; and a proton-conducting medium positioned between the photoanode and the cathode. Electrical charges associated with the protons and the electrons move from the photoanode to the cathode, driven in part by a chemical potential difference sufficient to drive the electrochemical reduction of CO.sub.2 at the cathode. A light beam is the sole source of energy used to drive chemical reactions. The photoanode can comprise TiO.sub.2 nanowires or nanotubes, and can also include WO.sub.3 nanowires or nanotubes, quantum dots of CdS or PbS, and Ag or Au nanostructures. The cathode can comprise a conductive gas diffusion layer with nanostructures of an electro-catalyst such as Cu or Co.

A novel cobalt-free layered GdBaFe 2O 5+ δ cathode for proton conducting solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Ding, Hanping; Xue, Xingjian

While cobalt-containing perovskite-type cathode materials facilitate the activation of oxygen reduction, they also suffer from problems like poor chemical stability in CO 2 and high thermal expansion coefficients. In this research, a cobalt-free layered GdBaFe 2O 5+ δ (GBF) perovskite was developed as a cathode material for protonic ceramic membrane fuel cells (PCMFCs) based on proton conducting electrolyte of stable BaZr 0.1Ce 0.7Y 0.2O 3- δ (BZCY7). The button cells of Ni-BZCY7|BZCY7|GBF were fabricated and characterized using complex impedance technique from 600 to 700 °C. An open-circuit potential of 1.007 V, maximum power density of 417 mW cm -2, and a low electrode polarization resistance of 0.18 Ω cm 2 were achieved at 700 °C. The results indicate that layered GBF perovskite is a good candidate for cobalt-free cathode material, while the developed Ni-BZCY7|BZCY7|GBF cell is a promising functional material system for solid oxide fuel cells.

The role of acids in electrical conduction through ice

NASA Astrophysics Data System (ADS)

Stillman, David E.; MacGregor, Joseph A.; Grimm, Robert E.

2013-03-01

Electrical conduction through meteoric polar ice is controlled by soluble impurities that originate mostly from sea salt, biomass burning, and volcanic eruptions. The strongest conductivity response is to acids, yet the mechanism causing this response has been unclear. Here we elucidate conduction mechanisms in ice using broadband dielectric spectroscopy of meteoric polar ice cores. We find that conduction through polycrystalline polar ice is consistent with Jaccard theory for migration of charged protonic point defects through single ice crystals, except that bulk DC conduction is impeded by grain boundaries. Neither our observations nor modeling using Archie's Law support the hypothesis that grain-boundary networks of unfrozen acids cause significant electrolytic conduction. Common electrical logs of ice cores (by electrical conductivity measurement [ECM] or dielectric profiling [DEP]) and the attenuation of radio waves in ice sheets thus respond to protonic point defects only. This response implies that joint interpretation of electrical and chemical logs can determine impurity partitioning between the lattice and grain boundaries or inclusions. For example, in the Greenland Ice Core Project (GRIP) ice core from central Greenland, on average more than half of the available lattice-soluble impurities (H+, Cl-, NH4+) create defects. Understanding this partitioning could help further resolve the nature of past changes in atmospheric chemistry.

Innovative polymer nanocomposite electrolytes: nanoscale manipulation of ion channels by functionalized graphenes.

PubMed

Choi, Bong Gill; Hong, Jinkee; Park, Young Chul; Jung, Doo Hwan; Hong, Won Hi; Hammond, Paula T; Park, Hoseok

2011-06-28

The chemistry and structure of ion channels within the polymer electrolytes are of prime importance for studying the transport properties of electrolytes as well as for developing high-performance electrochemical devices. Despite intensive efforts on the synthesis of polymer electrolytes, few studies have demonstrated enhanced target ion conduction while suppressing unfavorable ion or mass transport because the undesirable transport occurs through an identical pathway. Herein, we report an innovative, chemical strategy for the synthesis of polymer electrolytes whose ion-conducting channels are physically and chemically modulated by the ionic (not electronic) conductive, functionalized graphenes and for a fundamental understanding of ion and mass transport occurring in nanoscale ionic clusters. The functionalized graphenes controlled the state of water by means of nanoscale manipulation of the physical geometry and chemical functionality of ionic channels. Furthermore, the confinement of bound water within the reorganized nanochannels of composite membranes was confirmed by the enhanced proton conductivity at high temperature and the low activation energy for ionic conduction through a Grotthus-type mechanism. The selectively facilitated transport behavior of composite membranes such as high proton conductivity and low methanol crossover was attributed to the confined bound water, resulting in high-performance fuel cells.

Dynamics of laser-driven proton beam focusing and transport into solid density matter

NASA Astrophysics Data System (ADS)

Kim, J.; McGuffey, C.; Beg, F.; Wei, M.; Mariscal, D.; Chen, S.; Fuchs, J.

2016-10-01

Isochoric heating and local energy deposition capabilities make intense proton beams appealing for studying high energy density physics and the Fast Ignition of inertial confinement fusion. To study proton beam focusing that results in high beam density, experiments have been conducted using different target geometries irradiated by a kilojoule, 10 ps pulse of the OMEGA EP laser. The beam focus was measured by imaging beam-induced Cu K-alpha emission on a Cu foil that was positioned at a fixed distance. Compared to a free target, structured targets having shapes of wedge and cone show a brighter and narrower K-alpha radiation emission spot on a Cu foil indicating higher beam focusability. Experimentally observed images with proton radiography demonstrate the existence of transverse fields on the structures. Full-scale simulations including the contribution of a long pulse duration of the laser confirm that such fields can be caused by hot electrons moving through the structures. The simulated fields are strong enough to reflect the diverging main proton beam and pinch a transverse probe beam. Detailed simulation results including the beam focusing and transport of the focused intense proton beam in Cu foil will be presented. This work was supported by the National Laser User Facility Program through Award DE-NA0002034.

Neutron-Proton Scattering Experiments at ANKE-COSY

NASA Astrophysics Data System (ADS)

Kacharava, A.; Chiladze, D.; Chiladze, B.; Keshelashvili, I.; Lomidze, N.; Macharashvili, G.; McHedlishvili, D.; Nioradze, M.; Rathmann, F.; Ströher, H.; Wilkin, C.

2010-04-01

The nucleon-nucleon interaction (NN) is fundamental for the whole of nuclear physics and hence to the composition of matter as we know it. It has been demonstrated that stored, polarised beams and polarised internal targets are experimental tools of choice to probe spin effects in NN-scattering experiments. While the EDDA experiment has dramatically improved the proton-proton date base, information on spin observables in neutron-proton scattering is very incomplete above 800 MeV, resulting in large uncertainties in isoscalar n p phase shifts. Experiments at COSY, using a polarised deuteron beam or target, can lead to significant improvements in the situation through the study of quasi-free reactions on the neutron in the deuteron. Such a measurements has already been started at ANKE by using polarised deuterons on an unpolarised target to study the dp → ppn deuteron charge-exchange reaction and the full program with a polarised storage cell target just has been conducted. At low excitation energies of the final pp system, the spin observables are directly related to the spin- dependent parts of the neutron-proton charge-exchange amplitudes. Our measurement of the deuteron-proton spin correlations will allow us to determine the relative phases of these amplitudes in addition to their overall magnitudes.

Aqueous NaCl and CsCl Solutions Confined in Crystalline Slit-Shaped Silica Nanopores of Varying Degree of Protonation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ho, Tuan A.; Argyris, Dimitrios; Cole, David R.

2011-12-13

All-atom molecular dynamics simulations were conducted to study the dynamics of aqueous electrolyte solutions confined in slit-shaped silica nanopores of various degrees of protonation. Five degrees of protonation were prepared by randomly removing surface hydrogen atoms from fully protonated crystalline silica surfaces. Aqueous electrolyte solutions containing NaCl or CsCl salt were simulated at ambient conditions. In all cases, the ionic concentration was 1 M. The results were quantified in terms of atomic density distributions within the pores, and the self-diffusion coefficient along the direction parallel to the pore surface. We found evidence for ion-specific properties that depend on ion-surface, water-ion,more » and only in some cases ion-ion correlations. The degree of protonation strongly affects the structure, distribution, and the dynamic behavior of confined water and electrolytes. Cl -ions adsorb on the surface at large degrees of protonation, and their behavior does not depend significantly on the cation type (either Na + or Cs + ions are present in the systems considered). The cations show significant ion-specific behavior. Na + ions occupy different positions within the pore as the degree of protonation changes, while Cs + ions mainly remain near the pore center at all conditions considered. For a given degree of protonation, the planar self-diffusion coefficient of Cs + is always greater than that of Na + ions. The results are useful for better understanding transport under confinement, including brine behavior in the subsurface, with important applications such as environmental remediation.« less

Spin Observables in h Meson Photoproduction on the Proton

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tucker, Ross

2016-05-01

A series of experiments using a polarized beam incident on a polarized frozen spin target (FROST) was conducted at Jefferson Lab in 2010. Results presented here were taken during the second running period with the FROST target using the CEBAF Large Acceptance Spectrometer (CLAS) detector at Jefferson Lab, which used transversely-polarized protons in a butanol target and a circularly-polarized incident tagged photon beam with energies between 0:62 and 2:93 GeV. Data are presented for the F and T polarization observables for n meson photoproduction on the proton from W = 1:55 GeV to 1:80 GeV. The data presented here willmore » improve the world database and refine theoretical approaches of nucleon structure.« less

Tungsten fragmentation in nuclear reactions induced by high-energy cosmic-ray protons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chechenin, N. G., E-mail: chechenin@sinp.msu.ru; Chuvilskaya, T. V.; Shirokova, A. A.

2015-01-15

Tungsten fragmentation arising in nuclear reactions induced by cosmic-ray protons in space-vehicle electronics is considered. In modern technologies of integrated circuits featuring a three-dimensional layered architecture, tungsten is frequently used as a material for interlayer conducting connections. Within the preequilibrium model, tungsten-fragmentation features, including the cross sections for the elastic and inelastic scattering of protons of energy between 30 and 240 MeV; the yields of isotopes and isobars; their energy, charge, and mass distributions; and recoil energy spectra, are calculated on the basis of the TALYS and EMPIRE-II-19 codes. It is shown that tungsten fragmentation affects substantially forecasts of failuresmore » of space-vehicle electronics.« less

Analysis of proton irradiated n- and p-type strained FinFETs at low temperatures down to 100 K

NASA Astrophysics Data System (ADS)

Vicentis Caparroz, Luis Felipe; Mendes Bordallo, Caio Cesar; Martino, Joao Antonio; Simoen, Eddy; Claeys, Cor; Ghedini Der Agopian, Paula

2018-06-01

This paper studies the main low temperature electrical parameters of SOI n- and p-type FinFETs, standard and strained devices, submitted to proton irradiation. The study covers the range from room temperature down to 100 K, focusing on the threshold voltage (VTH), subthreshold swing (SS), the Early voltage VEA, transistor efficiency and the intrinsic gain voltage (AV) for 3 different channel widths. The p-channel devices showed a greater immunity to radiation than the n-channel ones, when considering the basic parameters thanks to the back conduction turn-off tendency, while from the analog parameters point of view, both transistor types presented a similar response to proton radiation at strong inversion.

Interfacial water on crystalline silica: a comparative molecular dynamics simulation study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ho, Tuan A.; Argyris, Dimitrios; Papavassiliou, Dimitrios V.

2011-03-03

All-atom molecular dynamics simulations were conducted to study the dynamics of aqueous electrolyte solutions confined in slit-shaped silica nanopores of various degrees of protonation. Five degrees of protonation were prepared by randomly removing surface hydrogen atoms from fully protonated crystalline silica surfaces. Aqueous electrolyte solutions containing NaCl or CsCl salt were simulated at ambient conditions. In all cases, the ionic concentration was 1 M. The results were quantified in terms of atomic density distributions within the pores, and the self-diffusion coefficient along the direction parallel to the pore surface. We found evidence for ion-specific properties that depend on ion surface,more » water ion, and only in some cases ion ion correlations. The degree of protonation strongly affects the structure, distribution, and the dynamic behavior of confined water and electrolytes. Cl ions adsorb on the surface at large degrees of protonation, and their behavior does not depend significantly on the cation type (either Na+ or Cs+ ions are present in the systems considered). The cations show significant ion-specific behavior. Na+ ions occupy different positions within the pore as the degree of protonation changes, while Cs+ ions mainly remain near the pore center at all conditions considered. For a given degree of protonation, the planar self-diffusion coefficient of Cs+ is always greater than that of Na+ ions. The results are useful for better understanding transport under confinement, including brine behavior in the subsurface, with important applications such as environmental remediation.« less

Biodegradation test of SPS-LS blends as polymer electrolyte membrane fuel cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Putri, Zufira, E-mail: zufira.putri@gmail.com, E-mail: arcana@chem.itb.ac.id; Arcana, I Made, E-mail: zufira.putri@gmail.com, E-mail: arcana@chem.itb.ac.id

Sulfonated polystyrene (SPS) can be applied as a proton exchange membrane fuel cell due to its fairly good chemical stability. In order to be applied as polymer electrolyte membrane fuel cells (PEMFCs), membrane polymer should have a good ionic conductivity, high proton conductivity, and high mechanical strength. Lignosulfonate (LS) is a complex biopolymer which has crosslinks and sulfonate groups. SPS-LS blends with addition of SiO{sub 2} are used to increase the proton conductivity and to improve the mechanical properties and thermal stability. However, the biodegradation test of SPS-LS blends is required to determine whether the application of these membranes tomore » be applied as an environmentally friendly membrane. In this study, had been done the synthesis of SPS, biodegradability test of SPS-LS blends with variations of LS and SiO{sub 2} compositions. The biodegradation test was carried out in solid medium of Luria Bertani (LB) with an activated sludge used as a source of microorganism at incubation temperature of 37°C. Based on the results obtained indicated that SPS-LS-SiO{sub 2} blends are more decomposed by microorganism than SPS-LS blends. This result is supported by analysis of weight reduction percentage, functional groups with Fourier Transform Infrared (FTIR) Spectroscopy, and morphological surface with Scanning Electron Microscopy (SEM)« less

Recent advances on Zeolite modification for direct alcohol fuel cells (DAFCs)

NASA Astrophysics Data System (ADS)

Makertihartha, I. G. B. N.; Zunita, M.; Rizki, Z.; Dharmawijaya, P. T.

2017-03-01

The increase of energy demand and global warming issues has driven studies of alternative energy sources. The polymer electrolyte membrane fuel cell (PEMFC) can be an alternative energy source by (partially) replacing the use of fossil fuel which is in line with the green technology concept. However, the usage of hydrogen as a fuel has several disadvantages mainly transportation and storage related to its safety aspects. Recently, alcohol has gained attention as an energy source for fuel cell application, namely direct alcohol fuel cell (DAFC). Among alcohols, high-mass energy density methanol and ethanol are widely used as direct methanol fuel cell (DMFC) and direct ethanol fuel cell (DEFC), respectively. Currently, the performance of DMFC is still rudimentary. Furthermore, the use of ethanol gives some additional privileges such as non-toxic property, renewable, ease of production in great quantity by the fermentation of sugar-containing raw materials. Direct alcohol fuel cell (DAFC) still has weakness in the low proton conductivity and high alcohol crossover. Therefore, to increase the performance of DAFC, modification using zeolite has been performed to improve proton conductivity and decrease alcohol crossover. Zeolite also has high thermal resistance properties, thereby increasing DAFC performance. This paper will discuss briefly about modification of catalyst and membrane for DAFC using zeolite. Zeolite modification effect on fuel cell performance especially proton conductivity and alcohol crossover will be presented in detail.

A self-regenerable soot sensor with a proton-conductive thin electrolyte and a nanostructured platinum sensing electrode.

PubMed

Lv, Peiling; Ito, Takenori; Oogushi, Akihide; Nakashima, Kensaku; Nagao, Masahiro; Hibino, Takashi

2016-11-18

In recent years, exhaust sensors have become increasingly attractive for use in energy and environmental technologies. Important issues regarding practical applications of these sensors, especially for soot measurements, include the further development of ion-conductive electrolytes and active electrode catalysts for meeting performance and durability requirements. Herein, we design a proton conductor with a high breakdown voltage and a sensing electrode with high sensitivity to electrochemical carbon oxidation, enabling continuous soot monitoring with self-regeneration of the sensor. A Si 0.97 Al 0.03 H x P 2 O 7-δ layer with an excellent balance between proton conductivity and voltage endurance was grown on the surface of a Si 0.97 Al 0.03 O 2-δ substrate by reacting it with liquid H 3 PO 4 at 600 °C. Specific reactivity of the electrochemically formed active oxygen toward soot was accomplished by adding a Pt-impregnated Sn 0.9 In 0.1 H x P 2 O 7-δ catalyst into a Pt sensing electrode. To make the best use of these optimized materials, a unipolar electrochemical device was fabricated by configuring the sensing and counter electrodes on the same surface of the electrolyte layer. The resulting amperometric mode sensor successfully produced a current signal that corresponded to the quantity of soot.

A self-regenerable soot sensor with a proton-conductive thin electrolyte and a nanostructured platinum sensing electrode

PubMed Central

Lv, Peiling; Ito, Takenori; Oogushi, Akihide; Nakashima, Kensaku; Nagao, Masahiro; Hibino, Takashi

2016-01-01

In recent years, exhaust sensors have become increasingly attractive for use in energy and environmental technologies. Important issues regarding practical applications of these sensors, especially for soot measurements, include the further development of ion-conductive electrolytes and active electrode catalysts for meeting performance and durability requirements. Herein, we design a proton conductor with a high breakdown voltage and a sensing electrode with high sensitivity to electrochemical carbon oxidation, enabling continuous soot monitoring with self-regeneration of the sensor. A Si0.97Al0.03HxP2O7-δ layer with an excellent balance between proton conductivity and voltage endurance was grown on the surface of a Si0.97Al0.03O2-δ substrate by reacting it with liquid H3PO4 at 600 °C. Specific reactivity of the electrochemically formed active oxygen toward soot was accomplished by adding a Pt-impregnated Sn0.9In0.1HxP2O7-δ catalyst into a Pt sensing electrode. To make the best use of these optimized materials, a unipolar electrochemical device was fabricated by configuring the sensing and counter electrodes on the same surface of the electrolyte layer. The resulting amperometric mode sensor successfully produced a current signal that corresponded to the quantity of soot. PMID:27857193

A self-regenerable soot sensor with a proton-conductive thin electrolyte and a nanostructured platinum sensing electrode

NASA Astrophysics Data System (ADS)

Lv, Peiling; Ito, Takenori; Oogushi, Akihide; Nakashima, Kensaku; Nagao, Masahiro; Hibino, Takashi

2016-11-01

In recent years, exhaust sensors have become increasingly attractive for use in energy and environmental technologies. Important issues regarding practical applications of these sensors, especially for soot measurements, include the further development of ion-conductive electrolytes and active electrode catalysts for meeting performance and durability requirements. Herein, we design a proton conductor with a high breakdown voltage and a sensing electrode with high sensitivity to electrochemical carbon oxidation, enabling continuous soot monitoring with self-regeneration of the sensor. A Si0.97Al0.03HxP2O7-δ layer with an excellent balance between proton conductivity and voltage endurance was grown on the surface of a Si0.97Al0.03O2-δ substrate by reacting it with liquid H3PO4 at 600 °C. Specific reactivity of the electrochemically formed active oxygen toward soot was accomplished by adding a Pt-impregnated Sn0.9In0.1HxP2O7-δ catalyst into a Pt sensing electrode. To make the best use of these optimized materials, a unipolar electrochemical device was fabricated by configuring the sensing and counter electrodes on the same surface of the electrolyte layer. The resulting amperometric mode sensor successfully produced a current signal that corresponded to the quantity of soot.

Evaluating the potential impact of proton carriers on syntrophic propionate oxidation

PubMed Central

Juste-Poinapen, Natacha M. S.; Turner, Mark S.; Rabaey, Korneel; Virdis, Bernardino; Batstone, Damien J.

2015-01-01

Anaerobic propionic acid degradation relies on interspecies electron transfer (IET) between propionate oxidisers and electron acceptor microorganisms, via either molecular hydrogen, formate or direct transfers. We evaluated the possibility of stimulating direct IET, hence enhancing propionate oxidation, by increasing availability of proton carriers to decrease solution resistance and reduce pH gradients. Phosphate was used as a proton carrying anion, and chloride as control ion together with potassium as counter ion. Propionic acid consumption in anaerobic granules was assessed in a square factorial design with ratios (1:0, 2:1, 1:1, 1:2 and 0:1) of total phosphate (TP) to Cl−, at 1X, 10X, and 30X native conductivity (1.5 mS.cm−1). Maximum specific uptake rate, half saturation, and time delay were estimated using model-based analysis. Community profiles were analysed by fluorescent in situ hybridisation and 16S rRNA gene pyrosequencing. The strongest performance was at balanced (1:1) ratios at 10X conductivity where presumptive propionate oxidisers namely Syntrophobacter and Candidatus Cloacamonas were more abundant. There was a shift from Methanobacteriales at high phosphate, to Methanosaeta at low TP:Cl ratios and low conductivity. A lack of response to TP, and low percentage of presumptive electroactive organisms suggested that DIET was not favoured under the current experimental conditions. PMID:26670292

Characterization of Polyethylene-Graft-Sulfonated Polyarylsulfone Proton Exchange Membranes for Direct Methanol Fuel Cell Applications.

PubMed

Kim, Hyung Kyu; Zhang, Gang; Nam, Changwoo; Chung, T C Mike

2015-12-04

This paper examines polymer film morphology and several important properties of polyethylene-graft-sulfonated polyarylene ether sulfone (PE-g-s-PAES) proton exchange membranes (PEMs) for direct methanol fuel cell applications. Due to the extreme surface energy differences between a semi-crystalline and hydrophobic PE backbone and several amorphous and hydrophilic s-PAES side chains, the PE-g-s-PAES membrane self-assembles into a unique morphology, with many proton conductive s-PAES channels embedded in the stable and tough PE matrix and a thin hydrophobic PE layer spontaneously formed on the membrane surfaces. In the bulk, these membranes show good mechanical properties (tensile strength >30 MPa, Young's modulus >1400 MPa) and low water swelling (λ < 15) even with high IEC >3 mmol/g in the s-PAES domains. On the surface, the thin hydrophobic and semi-crystalline PE layer shows some unusual barrier (protective) properties. In addition to exhibiting higher through-plane conductivity (up to 160 mS/cm) than in-plane conductivity, the PE surface layer minimizes methanol cross-over from anode to cathode with reduced fuel loss, and stops the HO• and HO₂• radicals, originally formed at the anode, entering into PEM matrix. Evidently, the thin PE surface layer provides a highly desirable protecting layer for PEMs to reduce fuel loss and increase chemical stability. Overall, the newly developed PE-g-s-PAES membranes offer a desirable set of PEM properties, including conductivity, selectivity, mechanical strength, stability, and cost-effectiveness for direct methanol fuel cell applications.

A-site deficient La0.2Sr0.7TiO3-δ anode material for proton conducting ethane fuel cell to cogenerate ethylene and electricity

NASA Astrophysics Data System (ADS)

Liu, Subiao; Behnamian, Yashar; Chuang, Karl T.; Liu, Qingxia; Luo, Jing-Li

2015-12-01

A site deficient La0.2Sr0.7TiO3-δ (LSTA) and a highly proton conductive electrolyte BaCe0.7Zr0.1Y0.2O3-δ (BCZY) are synthesized by using solid state reaction method. The performance of the electrolyte-supported single cell, comprised of LSTA + Cr2O3 + Cu//BCZY//(La0.60Sr0.40)0.95Co0.20Fe0.80O3-δ (LSCF)+BCZY, is fabricated and investigated. LSTA shows remarkably high electrical performance, with a conductivity as high as 27.78 Scm-1 at 1150 °C in a 10% H2/N2 reducing atmosphere. As a main anode component, it shows good catalytic activity towards the oxidation of ethane, causing the power density to considerably increase from 158.4 mW cm-2 to 320.9 mW cm-2 and the ethane conversion to significantly rise from 12.6% to 30.9%, when the temperature increases from 650 °C to 750 °C. These changes agree well with the polarization resistance which dramatically decreases from 0.346 Ωcm2 to 0.112 Ωcm2. EDX measurement shows that no element diffusion exists (chemical compatibility) between anode (LSTA + Cr2O3+Cu) and electrolyte (BCZY). With these properties, the pure phase LSTA is evaluated as a high electro-catalytic activity anode material for ethane proton conducting solid oxide fuel cell (PC-SOFC).

Characterization of Polyethylene-Graft-Sulfonated Polyarylsulfone Proton Exchange Membranes for Direct Methanol Fuel Cell Applications

PubMed Central

Kim, Hyung Kyu; Zhang, Gang; Nam, Changwoo; Chung, T.C. Mike

2015-01-01

This paper examines polymer film morphology and several important properties of polyethylene-graft-sulfonated polyarylene ether sulfone (PE-g-s-PAES) proton exchange membranes (PEMs) for direct methanol fuel cell applications. Due to the extreme surface energy differences between a semi-crystalline and hydrophobic PE backbone and several amorphous and hydrophilic s-PAES side chains, the PE-g-s-PAES membrane self-assembles into a unique morphology, with many proton conductive s-PAES channels embedded in the stable and tough PE matrix and a thin hydrophobic PE layer spontaneously formed on the membrane surfaces. In the bulk, these membranes show good mechanical properties (tensile strength >30 MPa, Young’s modulus >1400 MPa) and low water swelling (λ < 15) even with high IEC >3 mmol/g in the s-PAES domains. On the surface, the thin hydrophobic and semi-crystalline PE layer shows some unusual barrier (protective) properties. In addition to exhibiting higher through-plane conductivity (up to 160 mS/cm) than in-plane conductivity, the PE surface layer minimizes methanol cross-over from anode to cathode with reduced fuel loss, and stops the HO• and HO2• radicals, originally formed at the anode, entering into PEM matrix. Evidently, the thin PE surface layer provides a highly desirable protecting layer for PEMs to reduce fuel loss and increase chemical stability. Overall, the newly developed PE-g-s-PAES membranes offer a desirable set of PEM properties, including conductivity, selectivity, mechanical strength, stability, and cost-effectiveness for direct methanol fuel cell applications. PMID:26690232

New synthesis of nanopowders of proton conducting materials. A route to densified proton ceramics

NASA Astrophysics Data System (ADS)

Khani, Zohreh; Taillades-Jacquin, Mélanie; Taillades, Gilles; Marrony, Mathieu; Jones, Deborah J.; Rozière, Jacques

2009-04-01

Low temperature routes have been developed for the preparation of BaCe 0.9Y 0.1O 2.95 (BCY10) and BaZr 0.9Y 0.1O 2.95 (BZY10) in the form of nanoparticulate powders for use after densification as ceramic membranes for a proton ceramic fuel cell. These methods make use on the one hand of the chelation of metal (II), (III) and (IV) ions by acrylates (hydrogelation route) and on the other of the destabilisation and precipitation of micro-emulsions. Both routes lead to single phase yttrium doped barium cerate or zirconate perovskites, as observed by X-ray diffraction, after thermal treatment at 900 °C for 4 h for BCY10 and 800 °C for BZY10. These temperatures, lower than those usually used for preparation of barium cerate or zirconate, lead to oxide nanoparticles of size <40 nm. Dense ceramics (⩾95%) are obtained by sintering BCY10 pellets at 1350 °C and BZY10 pellets at 1500 °C for 10 h. The water uptake of compacted samples at 500 °C is 0.14 wt% for BCY10 and 0.26 wt% for BZY10. Total conductivities in the range 300-600 °C were determined using impedance spectroscopy in a humidified nitrogen atmosphere. The total conductivity was 1.8×10 -2 S/cm for BCY10 and 2×10 -3 S/cm for BZY10 at 600 °C. The smallest perovskite nanoparticles and highest conductivities were obtained by hydrogelation of precursor barium, zirconium, cerium and yttrium acrylates.

Search for long-lived charged particles in proton-proton collisions at √{s }=13 TeV

NASA Astrophysics Data System (ADS)

Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Brandstetter, J.; Brondolin, E.; Dragicevic, M.; Erö, J.; Flechl, M.; Friedl, M.; Frühwirth, R.; Ghete, V. M.; Hartl, C.; Hörmann, N.; Hrubec, J.; Jeitler, M.; König, A.; Krätschmer, I.; Liko, D.; Matsushita, T.; Mikulec, I.; Rabady, D.; Rad, N.; Rahbaran, B.; Rohringer, H.; Schieck, J.; Strauss, J.; Treberer-Treberspurg, W.; Waltenberger, W.; Wulz, C.-E.; Mossolov, V.; Shumeiko, N.; Suarez Gonzalez, J.; Alderweireldt, S.; De Wolf, E. A.; Janssen, X.; Lauwers, J.; Van De Klundert, M.; Van Haevermaet, H.; Van Mechelen, P.; Van Remortel, N.; Van Spilbeeck, A.; Abu Zeid, S.; Blekman, F.; D'Hondt, J.; Daci, N.; De Bruyn, I.; Deroover, K.; Heracleous, N.; Lowette, S.; Moortgat, S.; Moreels, L.; Olbrechts, A.; Python, Q.; Tavernier, S.; Van Doninck, W.; Van Mulders, P.; Van Parijs, I.; Brun, H.; Caillol, C.; Clerbaux, B.; De Lentdecker, G.; Delannoy, H.; Fasanella, G.; Favart, L.; Goldouzian, R.; Grebenyuk, A.; Karapostoli, G.; Lenzi, T.; Léonard, A.; Luetic, J.; Maerschalk, T.; Marinov, A.; Randle-conde, A.; Seva, T.; Vander Velde, C.; Vanlaer, P.; Yonamine, R.; Zenoni, F.; Zhang, F.; Cimmino, A.; Cornelis, T.; Dobur, D.; Fagot, A.; Garcia, G.; Gul, M.; Poyraz, D.; Salva, S.; Schöfbeck, R.; Sharma, A.; Tytgat, M.; Van Driessche, W.; Yazgan, E.; Zaganidis, N.; Bakhshiansohi, H.; Beluffi, C.; Bondu, O.; Brochet, S.; Bruno, G.; Caudron, A.; De Visscher, S.; Delaere, C.; Delcourt, M.; Francois, B.; Giammanco, A.; Jafari, A.; Jez, P.; Komm, M.; Lemaitre, V.; Magitteri, A.; Mertens, A.; Musich, M.; Nuttens, C.; Piotrzkowski, K.; Quertenmont, L.; Selvaggi, M.; Vidal Marono, M.; Wertz, S.; Zobec, J.; Beliy, N.; Aldá Júnior, W. L.; Alves, F. L.; Alves, G. A.; Brito, L.; Hensel, C.; Moraes, A.; Pol, M. E.; Rebello Teles, P.; Belchior Batista Das Chagas, E.; Carvalho, W.; Chinellato, J.; Custódio, A.; Da Costa, E. M.; Da Silveira, G. G.; De Jesus Damiao, D.; De Oliveira Martins, C.; Fonseca De Souza, S.; Huertas Guativa, L. M.; Malbouisson, H.; Matos Figueiredo, D.; Mora Herrera, C.; Mundim, L.; Nogima, H.; Prado Da Silva, W. L.; Santoro, A.; Sznajder, A.; Tonelli Manganote, E. J.; Vilela Pereira, A.; Ahuja, S.; Bernardes, C. A.; Dogra, S.; Fernandez Perez Tomei, T. R.; Gregores, E. M.; Mercadante, P. G.; Moon, C. S.; Novaes, S. F.; Padula, Sandra S.; Romero Abad, D.; Ruiz Vargas, J. C.; Aleksandrov, A.; Hadjiiska, R.; Iaydjiev, P.; Rodozov, M.; Stoykova, S.; Sultanov, G.; Vutova, M.; Dimitrov, A.; Glushkov, I.; Litov, L.; Pavlov, B.; Petkov, P.; Fang, W.; Ahmad, M.; Bian, J. G.; Chen, G. M.; Chen, H. S.; Chen, M.; Chen, Y.; Cheng, T.; Jiang, C. H.; Leggat, D.; Liu, Z.; Romeo, F.; Shaheen, S. M.; Spiezia, A.; Tao, J.; Wang, C.; Wang, Z.; Zhang, H.; Zhao, J.; Ban, Y.; Chen, G.; Li, Q.; Liu, S.; Mao, Y.; Qian, S. J.; Wang, D.; Xu, Z.; Avila, C.; Cabrera, A.; Chaparro Sierra, L. F.; Florez, C.; Gomez, J. P.; González Hernández, C. F.; Ruiz Alvarez, J. D.; Sanabria, J. C.; Godinovic, N.; Lelas, D.; Puljak, I.; Ribeiro Cipriano, P. M.; Sculac, T.; Antunovic, Z.; Kovac, M.; Brigljevic, V.; Ferencek, D.; Kadija, K.; Micanovic, S.; Sudic, L.; Susa, T.; Attikis, A.; Mavromanolakis, G.; Mousa, J.; Nicolaou, C.; Ptochos, F.; Razis, P. A.; Rykaczewski, H.; Finger, M.; Finger, M.; Carrera Jarrin, E.; Assran, Y.; Elkafrawy, T.; Mahrous, A.; Calpas, B.; Kadastik, M.; Murumaa, M.; Perrini, L.; Raidal, M.; Tiko, A.; Veelken, C.; Eerola, P.; Pekkanen, J.; Voutilainen, M.; Härkönen, J.; Karimäki, V.; Kinnunen, R.; Lampén, T.; Lassila-Perini, K.; Lehti, S.; Lindén, T.; Luukka, P.; Tuominiemi, J.; Tuovinen, E.; Wendland, L.; Talvitie, J.; Tuuva, T.; Besancon, M.; Couderc, F.; Dejardin, M.; Denegri, D.; Fabbro, B.; Faure, J. L.; Favaro, C.; Ferri, F.; Ganjour, S.; Ghosh, S.; Givernaud, A.; Gras, P.; Hamel de Monchenault, G.; Jarry, P.; Kucher, I.; Locci, E.; Machet, M.; Malcles, J.; Rander, J.; Rosowsky, A.; Titov, M.; Zghiche, A.; Abdulsalam, A.; Antropov, I.; Baffioni, S.; Beaudette, F.; Busson, P.; Cadamuro, L.; Chapon, E.; Charlot, C.; Davignon, O.; Granier de Cassagnac, R.; Jo, M.; Lisniak, S.; Miné, P.; Nguyen, M.; Ochando, C.; Ortona, G.; Paganini, P.; Pigard, P.; Regnard, S.; Salerno, R.; Sirois, Y.; Strebler, T.; Yilmaz, Y.; Zabi, A.; Agram, J.-L.; Andrea, J.; Aubin, A.; Bloch, D.; Brom, J.-M.; Buttignol, M.; Chabert, E. C.; Chanon, N.; Collard, C.; Conte, E.; Coubez, X.; Fontaine, J.-C.; Gelé, D.; Goerlach, U.; Le Bihan, A.-C.; Skovpen, K.; Van Hove, P.; Gadrat, S.; Beauceron, S.; Bernet, C.; Boudoul, G.; Bouvier, E.; Carrillo Montoya, C. A.; Chierici, R.; Contardo, D.; Courbon, B.; Depasse, P.; El Mamouni, H.; Fan, J.; Fay, J.; Gascon, S.; Gouzevitch, M.; Grenier, G.; Ille, B.; Lagarde, F.; Laktineh, I. B.; Lethuillier, M.; Mirabito, L.; Pequegnot, A. L.; Perries, S.; Popov, A.; Sabes, D.; Sordini, V.; Vander Donckt, M.; Verdier, P.; Viret, S.; Toriashvili, T.; Tsamalaidze, Z.; Autermann, C.; Beranek, S.; Feld, L.; Heister, A.; Kiesel, M. K.; Klein, K.; Lipinski, M.; Ostapchuk, A.; Preuten, M.; Raupach, F.; Schael, S.; Schomakers, C.; Schulte, J. F.; Schulz, J.; Verlage, T.; Weber, H.; Zhukov, V.; Albert, A.; Brodski, M.; Dietz-Laursonn, E.; Duchardt, D.; Endres, M.; Erdmann, M.; Erdweg, S.; Esch, T.; Fischer, R.; Güth, A.; Hamer, M.; Hebbeker, T.; Heidemann, C.; Hoepfner, K.; Knutzen, S.; Merschmeyer, M.; Meyer, A.; Millet, P.; Mukherjee, S.; Olschewski, M.; Padeken, K.; Pook, T.; Radziej, M.; Reithler, H.; Rieger, M.; Scheuch, F.; Sonnenschein, L.; Teyssier, D.; Thüer, S.; Cherepanov, V.; Flügge, G.; Haj Ahmad, W.; Hoehle, F.; Kargoll, B.; Kress, T.; Künsken, A.; Lingemann, J.; Müller, T.; Nehrkorn, A.; Nowack, A.; Nugent, I. M.; Pistone, C.; Pooth, O.; Stahl, A.; Aldaya Martin, M.; Asawatangtrakuldee, C.; Beernaert, K.; Behnke, O.; Behrens, U.; Bin Anuar, A. A.; Borras, K.; Campbell, A.; Connor, P.; Contreras-Campana, C.; Costanza, F.; Diez Pardos, C.; Dolinska, G.; Eckerlin, G.; Eckstein, D.; Eren, E.; Gallo, E.; Garay Garcia, J.; Geiser, A.; Gizhko, A.; Grados Luyando, J. M.; Gunnellini, P.; Harb, A.; Hauk, J.; Hempel, M.; Jung, H.; Kalogeropoulos, A.; Karacheban, O.; Kasemann, M.; Keaveney, J.; Kleinwort, C.; Korol, I.; Krücker, D.; Lange, W.; Lelek, A.; Leonard, J.; Lipka, K.; Lobanov, A.; Lohmann, W.; Mankel, R.; Melzer-Pellmann, I.-A.; Meyer, A. B.; Mittag, G.; Mnich, J.; Mussgiller, A.; Ntomari, E.; Pitzl, D.; Placakyte, R.; Raspereza, A.; Roland, B.; Sahin, M. Ö.; Saxena, P.; Schoerner-Sadenius, T.; Seitz, C.; Spannagel, S.; Stefaniuk, N.; Van Onsem, G. P.; Walsh, R.; Wissing, C.; Blobel, V.; Centis Vignali, M.; Draeger, A. R.; Dreyer, T.; Garutti, E.; Gonzalez, D.; Haller, J.; Hoffmann, M.; Junkes, A.; Klanner, R.; Kogler, R.; Kovalchuk, N.; Lapsien, T.; Lenz, T.; Marchesini, I.; Marconi, D.; Meyer, M.; Niedziela, M.; Nowatschin, D.; Pantaleo, F.; Peiffer, T.; Perieanu, A.; Poehlsen, J.; Sander, C.; Scharf, C.; Schleper, P.; Schmidt, A.; Schumann, S.; Schwandt, J.; Stadie, H.; Steinbrück, G.; Stober, F. M.; Stöver, M.; Tholen, H.; Troendle, D.; Usai, E.; Vanelderen, L.; Vanhoefer, A.; Vormwald, B.; Barth, C.; Baus, C.; Berger, J.; Butz, E.; Chwalek, T.; Colombo, F.; De Boer, W.; Dierlamm, A.; Fink, S.; Friese, R.; Giffels, M.; Gilbert, A.; Goldenzweig, P.; Haitz, D.; Hartmann, F.; Heindl, S. M.; Husemann, U.; Katkov, I.; Lobelle Pardo, P.; Maier, B.; Mildner, H.; Mozer, M. U.; Müller, Th.; Plagge, M.; Quast, G.; Rabbertz, K.; Röcker, S.; Roscher, F.; Schröder, M.; Shvetsov, I.; Sieber, G.; Simonis, H. J.; Ulrich, R.; Wagner-Kuhr, J.; Wayand, S.; Weber, M.; Weiler, T.; Williamson, S.; Wöhrmann, C.; Wolf, R.; Anagnostou, G.; Daskalakis, G.; Geralis, T.; Giakoumopoulou, V. A.; Kyriakis, A.; Loukas, D.; Topsis-Giotis, I.; Kesisoglou, S.; Panagiotou, A.; Saoulidou, N.; Tziaferi, E.; Evangelou, I.; Flouris, G.; Foudas, C.; Kokkas, P.; Loukas, N.; Manthos, N.; Papadopoulos, I.; Paradas, E.; Filipovic, N.; Bencze, G.; Hajdu, C.; Hidas, P.; Horvath, D.; Sikler, F.; Veszpremi, V.; Vesztergombi, G.; Zsigmond, A. J.; Beni, N.; Czellar, S.; Karancsi, J.; Makovec, A.; Molnar, J.; Szillasi, Z.; Bartók, M.; Raics, P.; Trocsanyi, Z. L.; Ujvari, B.; Bahinipati, S.; Choudhury, S.; Mal, P.; Mandal, K.; Nayak, A.; Sahoo, D. K.; Sahoo, N.; Swain, S. K.; Bansal, S.; Beri, S. B.; Bhatnagar, V.; Chawla, R.; Bhawandeep, U.; Kalsi, A. K.; Kaur, A.; Kaur, M.; Kumar, R.; Mehta, A.; Mittal, M.; Singh, J. B.; Walia, G.; Kumar, Ashok; Bhardwaj, A.; Choudhary, B. C.; Garg, R. B.; Keshri, S.; Malhotra, S.; Naimuddin, M.; Nishu, N.; Ranjan, K.; Sharma, R.; Sharma, V.; Bhattacharya, R.; Bhattacharya, S.; Chatterjee, K.; Dey, S.; Dutt, S.; Dutta, S.; Ghosh, S.; Majumdar, N.; Modak, A.; Mondal, K.; Mukhopadhyay, S.; Nandan, S.; Purohit, A.; Roy, A.; Roy, D.; Roy Chowdhury, S.; Sarkar, S.; Sharan, M.; Thakur, S.; Behera, P. K.; Chudasama, R.; Dutta, D.; Jha, V.; Kumar, V.; Mohanty, A. K.; Netrakanti, P. K.; Pant, L. M.; Shukla, P.; Topkar, A.; Aziz, T.; Dugad, S.; Kole, G.; Mahakud, B.; Mitra, S.; Mohanty, G. B.; Parida, B.; Sur, N.; Sutar, B.; Banerjee, S.; Bhowmik, S.; Dewanjee, R. K.; Ganguly, S.; Guchait, M.; Jain, Sa.; Kumar, S.; Maity, M.; Majumder, G.; Mazumdar, K.; Sarkar, T.; Wickramage, N.; Chauhan, S.; Dube, S.; Hegde, V.; Kapoor, A.; Kothekar, K.; Rane, A.; Sharma, S.; Behnamian, H.; Chenarani, S.; Eskandari Tadavani, E.; Etesami, S. M.; Fahim, A.; Khakzad, M.; Mohammadi Najafabadi, M.; Naseri, M.; Paktinat Mehdiabadi, S.; Rezaei Hosseinabadi, F.; Safarzadeh, B.; Zeinali, M.; Felcini, M.; Grunewald, M.; Abbrescia, M.; Calabria, C.; Caputo, C.; Colaleo, A.; Creanza, D.; Cristella, L.; De Filippis, N.; De Palma, M.; Fiore, L.; Iaselli, G.; Maggi, G.; Maggi, M.; Miniello, G.; My, S.; Nuzzo, S.; Pompili, A.; Pugliese, G.; Radogna, R.; Ranieri, A.; Selvaggi, G.; Silvestris, L.; Venditti, R.; Verwilligen, P.; Abbiendi, G.; Battilana, C.; Bonacorsi, D.; Braibant-Giacomelli, S.; Brigliadori, L.; Campanini, R.; Capiluppi, P.; Castro, A.; Cavallo, F. R.; Chhibra, S. S.; Codispoti, G.; Cuffiani, M.; Dallavalle, G. M.; Fabbri, F.; Fanfani, A.; Fasanella, D.; Giacomelli, P.; Grandi, C.; Guiducci, L.; Marcellini, S.; Masetti, G.; Montanari, A.; Navarria, F. L.; Perrotta, A.; Rossi, A. M.; Rovelli, T.; Siroli, G. 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M.; Lanza, G.; Lista, L.; Meola, S.; Paolucci, P.; Sciacca, C.; Thyssen, F.; Azzi, P.; Bacchetta, N.; Benato, L.; Biasotto, M.; Boletti, A.; Carvalho Antunes De Oliveira, A.; Checchia, P.; Dall'Osso, M.; De Castro Manzano, P.; Dorigo, T.; Fanzago, F.; Gasparini, F.; Gasparini, U.; Gozzelino, A.; Lacaprara, S.; Margoni, M.; Maron, G.; Meneguzzo, A. T.; Pazzini, J.; Pozzobon, N.; Ronchese, P.; Simonetto, F.; Torassa, E.; Zanetti, M.; Zotto, P.; Zucchetta, A.; Zumerle, G.; Braghieri, A.; Magnani, A.; Montagna, P.; Ratti, S. P.; Re, V.; Riccardi, C.; Salvini, P.; Vai, I.; Vitulo, P.; Alunni Solestizi, L.; Bilei, G. M.; Ciangottini, D.; Fanò, L.; Lariccia, P.; Leonardi, R.; Mantovani, G.; Menichelli, M.; Saha, A.; Santocchia, A.; Androsov, K.; Azzurri, P.; Bagliesi, G.; Bernardini, J.; Boccali, T.; Castaldi, R.; Ciocci, M. A.; Dell'Orso, R.; Donato, S.; Fedi, G.; Giassi, A.; Grippo, M. T.; Ligabue, F.; Lomtadze, T.; Martini, L.; Messineo, A.; Palla, F.; Rizzi, A.; Savoy-Navarro, A.; Spagnolo, P.; Tenchini, R.; Tonelli, G.; Venturi, A.; Verdini, P. G.; Barone, L.; Cavallari, F.; Cipriani, M.; D'imperio, G.; Del Re, D.; Diemoz, M.; Gelli, S.; Longo, E.; Margaroli, F.; Meridiani, P.; Organtini, G.; Paramatti, R.; Preiato, F.; Rahatlou, S.; Rovelli, C.; Santanastasio, F.; Amapane, N.; Arcidiacono, R.; Argiro, S.; Arneodo, M.; Bartosik, N.; Bellan, R.; Biino, C.; Cartiglia, N.; Costa, M.; Cotto, G.; Covarelli, R.; Dattola, D.; Degano, A.; Demaria, N.; Finco, L.; Kiani, B.; Mariotti, C.; Maselli, S.; Migliore, E.; Monaco, V.; Monteil, E.; Obertino, M. M.; Pacher, L.; Pastrone, N.; Pelliccioni, M.; Pinna Angioni, G. L.; Ravera, F.; Romero, A.; Ruspa, M.; Sacchi, R.; Sola, V.; Solano, A.; Staiano, A.; Traczyk, P.; Belforte, S.; Casarsa, M.; Cossutti, F.; Della Ricca, G.; La Licata, C.; Schizzi, A.; Zanetti, A.; Kim, D. H.; Kim, G. N.; Kim, M. S.; Lee, S.; Lee, S. W.; Oh, Y. D.; Sekmen, S.; Son, D. C.; Yang, Y. C.; Lee, A.; Kim, H.; Brochero Cifuentes, J. A.; Kim, T. J.; Cho, S.; Choi, S.; Go, Y.; Gyun, D.; Ha, S.; Hong, B.; Jo, Y.; Kim, Y.; Lee, B.; Lee, K.; Lee, K. S.; Lee, S.; Lim, J.; Park, S. K.; Roh, Y.; Almond, J.; Kim, J.; Lee, H.; Oh, S. B.; Radburn-Smith, B. C.; Seo, S. h.; Yang, U. K.; Yoo, H. D.; Yu, G. B.; Choi, M.; Kim, H.; Kim, J. H.; Lee, J. S. H.; Park, I. C.; Ryu, G.; Ryu, M. S.; Choi, Y.; Goh, J.; Hwang, C.; Lee, J.; Yu, I.; Dudenas, V.; Juodagalvis, A.; Vaitkus, J.; Ahmed, I.; Ibrahim, Z. A.; Komaragiri, J. R.; Md Ali, M. A. B.; Mohamad Idris, F.; Wan Abdullah, W. A. T.; Yusli, M. N.; Zolkapli, Z.; Castilla-Valdez, H.; De La Cruz-Burelo, E.; Heredia-De La Cruz, I.; Hernandez-Almada, A.; Lopez-Fernandez, R.; Magaña Villalba, R.; Mejia Guisao, J.; Sanchez-Hernandez, A.; Carrillo Moreno, S.; Oropeza Barrera, C.; Vazquez Valencia, F.; Carpinteyro, S.; Pedraza, I.; Salazar Ibarguen, H. A.; Uribe Estrada, C.; Morelos Pineda, A.; Krofcheck, D.; Butler, P. H.; Ahmad, A.; Ahmad, M.; Hassan, Q.; Hoorani, H. R.; Khan, W. A.; Shah, M. A.; Shoaib, M.; Waqas, M.; Bialkowska, H.; Bluj, M.; Boimska, B.; Frueboes, T.; Górski, M.; Kazana, M.; Nawrocki, K.; Romanowska-Rybinska, K.; Szleper, M.; Zalewski, P.; Bunkowski, K.; Byszuk, A.; Doroba, K.; Kalinowski, A.; Konecki, M.; Krolikowski, J.; Misiura, M.; Olszewski, M.; Walczak, M.; Bargassa, P.; Beirão Da Cruz E Silva, C.; Di Francesco, A.; Faccioli, P.; Ferreira Parracho, P. G.; Gallinaro, M.; Hollar, J.; Leonardo, N.; Lloret Iglesias, L.; Nemallapudi, M. V.; Rodrigues Antunes, J.; Seixas, J.; Toldaiev, O.; Vadruccio, D.; Varela, J.; Vischia, P.; Alexakhin, V.; Golutvin, I.; Gorbunov, I.; Karjavin, V.; Korenkov, V.; Lanev, A.; Malakhov, A.; Matveev, V.; Mitsyn, V. V.; Moisenz, P.; Palichik, V.; Perelygin, V.; Savina, M.; Shmatov, S.; Shulha, S.; Skatchkov, N.; Smirnov, V.; Tikhonenko, E.; Zarubin, A.; Chtchipounov, L.; Golovtsov, V.; Ivanov, Y.; Kim, V.; Kuznetsova, E.; Murzin, V.; Oreshkin, V.; Sulimov, V.; Vorobyev, A.; Andreev, Yu.; Dermenev, A.; Gninenko, S.; Golubev, N.; Karneyeu, A.; Kirsanov, M.; Krasnikov, N.; Pashenkov, A.; Tlisov, D.; Toropin, A.; Epshteyn, V.; Gavrilov, V.; Lychkovskaya, N.; Popov, V.; Pozdnyakov, I.; Safronov, G.; Spiridonov, A.; Toms, M.; Vlasov, E.; Zhokin, A.; Bylinkin, A.; Chistov, R.; Danilov, M.; Rusinov, V.; Andreev, V.; Azarkin, M.; Dremin, I.; Kirakosyan, M.; Leonidov, A.; Rusakov, S. V.; Terkulov, A.; Baskakov, A.; Belyaev, A.; Boos, E.; Dubinin, M.; Dudko, L.; Ershov, A.; Gribushin, A.; Klyukhin, V.; Kodolova, O.; Lokhtin, I.; Miagkov, I.; Obraztsov, S.; Petrushanko, S.; Savrin, V.; Snigirev, A.; Blinov, V.; Skovpen, Y.; Azhgirey, I.; Bayshev, I.; Bitioukov, S.; Elumakhov, D.; Kachanov, V.; Kalinin, A.; Konstantinov, D.; Krychkine, V.; Petrov, V.; Ryutin, R.; Sobol, A.; Troshin, S.; Tyurin, N.; Uzunian, A.; Volkov, A.; Adzic, P.; Cirkovic, P.; Devetak, D.; Dordevic, M.; Milosevic, J.; Rekovic, V.; Alcaraz Maestre, J.; Barrio Luna, M.; Calvo, E.; Cerrada, M.; Chamizo Llatas, M.; Colino, N.; De La Cruz, B.; Delgado Peris, A.; Escalante Del Valle, A.; Fernandez Bedoya, C.; Fernández Ramos, J. P.; Flix, J.; Fouz, M. C.; Garcia-Abia, P.; Gonzalez Lopez, O.; Goy Lopez, S.; Hernandez, J. M.; Josa, M. I.; Navarro De Martino, E.; Pérez-Calero Yzquierdo, A.; Puerta Pelayo, J.; Quintario Olmeda, A.; Redondo, I.; Romero, L.; Soares, M. S.; de Trocóniz, J. F.; Missiroli, M.; Moran, D.; Cuevas, J.; Fernandez Menendez, J.; Gonzalez Caballero, I.; González Fernández, J. R.; Palencia Cortezon, E.; Sanchez Cruz, S.; Suárez Andrés, I.; Vizan Garcia, J. M.; Cabrillo, I. J.; Calderon, A.; Castiñeiras De Saa, J. R.; Curras, E.; Fernandez, M.; Garcia-Ferrero, J.; Gomez, G.; Lopez Virto, A.; Marco, J.; Martinez Rivero, C.; Matorras, F.; Piedra Gomez, J.; Rodrigo, T.; Ruiz-Jimeno, A.; Scodellaro, L.; Trevisani, N.; Vila, I.; Vilar Cortabitarte, R.; Abbaneo, D.; Auffray, E.; Auzinger, G.; Bachtis, M.; Baillon, P.; Ball, A. H.; Barney, D.; Bloch, P.; Bocci, A.; Bonato, A.; Botta, C.; Camporesi, T.; Castello, R.; Cepeda, M.; Cerminara, G.; D'Alfonso, M.; d'Enterria, D.; Dabrowski, A.; Daponte, V.; David, A.; De Gruttola, M.; De Roeck, A.; Di Marco, E.; Dobson, M.; Dorney, B.; du Pree, T.; Duggan, D.; Dünser, M.; Dupont, N.; Elliott-Peisert, A.; Fartoukh, S.; Franzoni, G.; Fulcher, J.; Funk, W.; Gigi, D.; Gill, K.; Girone, M.; Glege, F.; Gulhan, D.; Gundacker, S.; Guthoff, M.; Hammer, J.; Harris, P.; Hegeman, J.; Innocente, V.; Janot, P.; Kieseler, J.; Kirschenmann, H.; Knünz, V.; Kornmayer, A.; Kortelainen, M. J.; Kousouris, K.; Krammer, M.; Lange, C.; Lecoq, P.; Lourenço, C.; Lucchini, M. T.; Malgeri, L.; Mannelli, M.; Martelli, A.; Meijers, F.; Merlin, J. A.; Mersi, S.; Meschi, E.; Moortgat, F.; Morovic, S.; Mulders, M.; Neugebauer, H.; Orfanelli, S.; Orsini, L.; Pape, L.; Perez, E.; Peruzzi, M.; Petrilli, A.; Petrucciani, G.; Pfeiffer, A.; Pierini, M.; Racz, A.; Reis, T.; Rolandi, G.; Rovere, M.; Ruan, M.; Sakulin, H.; Sauvan, J. B.; Schäfer, C.; Schwick, C.; Seidel, M.; Sharma, A.; Silva, P.; Sphicas, P.; Steggemann, J.; Stoye, M.; Takahashi, Y.; Tosi, M.; Treille, D.; Triossi, A.; Tsirou, A.; Veckalns, V.; Veres, G. I.; Wardle, N.; Wöhri, H. K.; Zagozdzinska, A.; Zeuner, W. D.; Bertl, W.; Deiters, K.; Erdmann, W.; Horisberger, R.; Ingram, Q.; Kaestli, H. C.; Kotlinski, D.; Langenegger, U.; Rohe, T.; Bachmair, F.; Bäni, L.; Bianchini, L.; Casal, B.; Dissertori, G.; Dittmar, M.; Donegà, M.; Grab, C.; Heidegger, C.; Hits, D.; Hoss, J.; Kasieczka, G.; Lecomte, P.; Lustermann, W.; Mangano, B.; Marionneau, M.; Martinez Ruiz del Arbol, P.; Masciovecchio, M.; Meinhard, M. T.; Meister, D.; Micheli, F.; Musella, P.; Nessi-Tedaldi, F.; Pandolfi, F.; Pata, J.; Pauss, F.; Perrin, G.; Perrozzi, L.; Quittnat, M.; Rossini, M.; Schönenberger, M.; Starodumov, A.; Tavolaro, V. R.; Theofilatos, K.; Wallny, R.; Aarrestad, T. K.; Amsler, C.; Caminada, L.; Canelli, M. F.; De Cosa, A.; Galloni, C.; Hinzmann, A.; Hreus, T.; Kilminster, B.; Ngadiuba, J.; Pinna, D.; Rauco, G.; Robmann, P.; Salerno, D.; Yang, Y.; Candelise, V.; Doan, T. H.; Jain, Sh.; Khurana, R.; Konyushikhin, M.; Kuo, C. M.; Lin, W.; Lu, Y. J.; Pozdnyakov, A.; Yu, S. S.; Kumar, Arun; Chang, P.; Chang, Y. H.; Chang, Y. W.; Chao, Y.; Chen, K. F.; Chen, P. H.; Dietz, C.; Fiori, F.; Hou, W.-S.; Hsiung, Y.; Liu, Y. F.; Lu, R.-S.; Miñano Moya, M.; Paganis, E.; Psallidas, A.; Tsai, J. f.; Tzeng, Y. M.; Asavapibhop, B.; Singh, G.; Srimanobhas, N.; Suwonjandee, N.; Cerci, S.; Damarseckin, S.; Demiroglu, Z. S.; Dozen, C.; Dumanoglu, I.; Girgis, S.; Gokbulut, G.; Guler, Y.; Gurpinar, E.; Hos, I.; Kangal, E. E.; Kara, O.; Kayis Topaksu, A.; Kiminsu, U.; Oglakci, M.; Onengut, G.; Ozdemir, K.; Sunar Cerci, D.; Topakli, H.; Turkcapar, S.; Zorbakir, I. S.; Zorbilmez, C.; Bilin, B.; Bilmis, S.; Isildak, B.; Karapinar, G.; Yalvac, M.; Zeyrek, M.; Gülmez, E.; Kaya, M.; Kaya, O.; Yetkin, E. A.; Yetkin, T.; Cakir, A.; Cankocak, K.; Sen, S.; Grynyov, B.; Levchuk, L.; Sorokin, P.; Aggleton, R.; Ball, F.; Beck, L.; Brooke, J. J.; Burns, D.; Clement, E.; Cussans, D.; Flacher, H.; Goldstein, J.; Grimes, M.; Heath, G. P.; Heath, H. F.; Jacob, J.; Kreczko, L.; Lucas, C.; Newbold, D. M.; Paramesvaran, S.; Poll, A.; Sakuma, T.; Seif El Nasr-storey, S.; Smith, D.; Smith, V. J.; Bell, K. W.; Belyaev, A.; Brew, C.; Brown, R. M.; Calligaris, L.; Cieri, D.; Cockerill, D. J. A.; Coughlan, J. A.; Harder, K.; Harper, S.; Olaiya, E.; Petyt, D.; Shepherd-Themistocleous, C. H.; Thea, A.; Tomalin, I. R.; Williams, T.; Baber, M.; Bainbridge, R.; Buchmuller, O.; Bundock, A.; Burton, D.; Casasso, S.; Citron, M.; Colling, D.; Corpe, L.; Dauncey, P.; Davies, G.; De Wit, A.; Della Negra, M.; Di Maria, R.; Dunne, P.; Elwood, A.; Futyan, D.; Haddad, Y.; Hall, G.; Iles, G.; James, T.; Lane, R.; Laner, C.; Lucas, R.; Lyons, L.; Magnan, A.-M.; Malik, S.; Mastrolorenzo, L.; Nash, J.; Nikitenko, A.; Pela, J.; Penning, B.; Pesaresi, M.; Raymond, D. M.; Richards, A.; Rose, A.; Seez, C.; Summers, S.; Tapper, A.; Uchida, K.; Vazquez Acosta, M.; Virdee, T.; Wright, J.; Zenz, S. C.; Cole, J. E.; Hobson, P. R.; Khan, A.; Kyberd, P.; Leslie, D.; Reid, I. D.; Symonds, P.; Teodorescu, L.; Turner, M.; Borzou, A.; Call, K.; Dittmann, J.; Hatakeyama, K.; Liu, H.; Pastika, N.; Charaf, O.; Cooper, S. I.; Henderson, C.; Rumerio, P.; West, C.; Arcaro, D.; Avetisyan, A.; Bose, T.; Gastler, D.; Rankin, D.; Richardson, C.; Rohlf, J.; Sulak, L.; Zou, D.; Benelli, G.; Berry, E.; Cutts, D.; Garabedian, A.; Hakala, J.; Heintz, U.; Hogan, J. M.; Jesus, O.; Laird, E.; Landsberg, G.; Mao, Z.; Narain, M.; Piperov, S.; Sagir, S.; Spencer, E.; Syarif, R.; Breedon, R.; Breto, G.; Burns, D.; Calderon De La Barca Sanchez, M.; Chauhan, S.; Chertok, M.; Conway, J.; Conway, R.; Cox, P. T.; Erbacher, R.; Flores, C.; Funk, G.; Gardner, M.; Ko, W.; Lander, R.; Mclean, C.; Mulhearn, M.; Pellett, D.; Pilot, J.; Shalhout, S.; Smith, J.; Squires, M.; Stolp, D.; Tripathi, M.; Wilbur, S.; Yohay, R.; Cousins, R.; Everaerts, P.; Florent, A.; Hauser, J.; Ignatenko, M.; Saltzberg, D.; Takasugi, E.; Valuev, V.; Weber, M.; Burt, K.; Clare, R.; Ellison, J.; Gary, J. W.; Hanson, G.; Heilman, J.; Jandir, P.; Kennedy, E.; Lacroix, F.; Long, O. R.; Olmedo Negrete, M.; Paneva, M. I.; Shrinivas, A.; Si, W.; Wei, H.; Wimpenny, S.; Yates, B. R.; Branson, J. G.; Cerati, G. B.; Cittolin, S.; Derdzinski, M.; Gerosa, R.; Holzner, A.; Klein, D.; Krutelyov, V.; Letts, J.; Macneill, I.; Olivito, D.; Padhi, S.; Pieri, M.; Sani, M.; Sharma, V.; Simon, S.; Tadel, M.; Vartak, A.; Wasserbaech, S.; Welke, C.; Wood, J.; Würthwein, F.; Yagil, A.; Zevi Della Porta, G.; Bhandari, R.; Bradmiller-Feld, J.; Campagnari, C.; Dishaw, A.; Dutta, V.; Flowers, K.; Franco Sevilla, M.; Geffert, P.; George, C.; Golf, F.; Gouskos, L.; Gran, J.; Heller, R.; Incandela, J.; Mccoll, N.; Mullin, S. D.; Ovcharova, A.; Richman, J.; Stuart, D.; Suarez, I.; Yoo, J.; Anderson, D.; Apresyan, A.; Bendavid, J.; Bornheim, A.; Bunn, J.; Chen, Y.; Duarte, J.; Lawhorn, J. M.; Mott, A.; Newman, H. B.; Pena, C.; Spiropulu, M.; Vlimant, J. R.; Xie, S.; Zhu, R. Y.; Andrews, M. B.; Azzolini, V.; Ferguson, T.; Paulini, M.; Russ, J.; Sun, M.; Vogel, H.; Vorobiev, I.; Cumalat, J. P.; Ford, W. T.; Jensen, F.; Johnson, A.; Krohn, M.; Mulholland, T.; Stenson, K.; Wagner, S. R.; Alexander, J.; Chaves, J.; Chu, J.; Dittmer, S.; Mcdermott, K.; Mirman, N.; Nicolas Kaufman, G.; Patterson, J. R.; Rinkevicius, A.; Ryd, A.; Skinnari, L.; Soffi, L.; Tan, S. M.; Tao, Z.; Thom, J.; Tucker, J.; Wittich, P.; Zientek, M.; Winn, D.; Abdullin, S.; Albrow, M.; Apollinari, G.; Banerjee, S.; Bauerdick, L. A. T.; Beretvas, A.; Berryhill, J.; Bhat, P. C.; Bolla, G.; Burkett, K.; Butler, J. N.; Cheung, H. W. K.; Chlebana, F.; Cihangir, S.; Cremonesi, M.; Elvira, V. D.; Fisk, I.; Freeman, J.; Gottschalk, E.; Gray, L.; Green, D.; Grünendahl, S.; Gutsche, O.; Hare, D.; Harris, R. M.; Hasegawa, S.; Hirschauer, J.; Hu, Z.; Jayatilaka, B.; Jindariani, S.; Johnson, M.; Joshi, U.; Klima, B.; Kreis, B.; Lammel, S.; Linacre, J.; Lincoln, D.; Lipton, R.; Liu, T.; Lopes De Sá, R.; Lykken, J.; Maeshima, K.; Magini, N.; Marraffino, J. M.; Maruyama, S.; Mason, D.; McBride, P.; Merkel, P.; Mrenna, S.; Nahn, S.; Newman-Holmes, C.; O'Dell, V.; Pedro, K.; Prokofyev, O.; Rakness, G.; Ristori, L.; Sexton-Kennedy, E.; Soha, A.; Spalding, W. J.; Spiegel, L.; Stoynev, S.; Strobbe, N.; Taylor, L.; Tkaczyk, S.; Tran, N. V.; Uplegger, L.; Vaandering, E. W.; Vernieri, C.; Verzocchi, M.; Vidal, R.; Wang, M.; Weber, H. A.; Whitbeck, A.; Acosta, D.; Avery, P.; Bortignon, P.; Bourilkov, D.; Brinkerhoff, A.; Carnes, A.; Carver, M.; Curry, D.; Das, S.; Field, R. D.; Furic, I. K.; Konigsberg, J.; Korytov, A.; Ma, P.; Matchev, K.; Mei, H.; Milenovic, P.; Mitselmakher, G.; Rank, D.; Shchutska, L.; Sperka, D.; Thomas, L.; Wang, J.; Wang, S.; Yelton, J.; Linn, S.; Markowitz, P.; Martinez, G.; Rodriguez, J. L.; Ackert, A.; Adams, J. R.; Adams, T.; Askew, A.; Bein, S.; Diamond, B.; Hagopian, S.; Hagopian, V.; Johnson, K. F.; Khatiwada, A.; Prosper, H.; Santra, A.; Weinberg, M.; Baarmand, M. M.; Bhopatkar, V.; Colafranceschi, S.; Hohlmann, M.; Noonan, D.; Roy, T.; Yumiceva, F.; Adams, M. R.; Apanasevich, L.; Berry, D.; Betts, R. R.; Bucinskaite, I.; Cavanaugh, R.; Evdokimov, O.; Gauthier, L.; Gerber, C. E.; Hofman, D. J.; Kurt, P.; O'Brien, C.; Sandoval Gonzalez, I. D.; Turner, P.; Varelas, N.; Wang, H.; Wu, Z.; Zakaria, M.; Zhang, J.; Bilki, B.; Clarida, W.; Dilsiz, K.; Durgut, S.; Gandrajula, R. P.; Haytmyradov, M.; Khristenko, V.; Merlo, J.-P.; Mermerkaya, H.; Mestvirishvili, A.; Moeller, A.; Nachtman, J.; Ogul, H.; Onel, Y.; Ozok, F.; Penzo, A.; Snyder, C.; Tiras, E.; Wetzel, J.; Yi, K.; Anderson, I.; Blumenfeld, B.; Cocoros, A.; Eminizer, N.; Fehling, D.; Feng, L.; Gritsan, A. V.; Maksimovic, P.; Osherson, M.; Roskes, J.; Sarica, U.; Swartz, M.; Xiao, M.; Xin, Y.; You, C.; Al-bataineh, A.; Baringer, P.; Bean, A.; Boren, S.; Bowen, J.; Bruner, C.; Castle, J.; Forthomme, L.; Kenny, R. P.; Kropivnitskaya, A.; Majumder, D.; Mcbrayer, W.; Murray, M.; Sanders, S.; Stringer, R.; Tapia Takaki, J. D.; Wang, Q.; Ivanov, A.; Kaadze, K.; Khalil, S.; Makouski, M.; Maravin, Y.; Mohammadi, A.; Saini, L. K.; Skhirtladze, N.; Toda, S.; Rebassoo, F.; Wright, D.; Anelli, C.; Baden, A.; Baron, O.; Belloni, A.; Calvert, B.; Eno, S. C.; Ferraioli, C.; Gomez, J. A.; Hadley, N. J.; Jabeen, S.; Kellogg, R. G.; Kolberg, T.; Kunkle, J.; Lu, Y.; Mignerey, A. C.; Ricci-Tam, F.; Shin, Y. H.; Skuja, A.; Tonjes, M. B.; Tonwar, S. C.; Abercrombie, D.; Allen, B.; Apyan, A.; Barbieri, R.; Baty, A.; Bi, R.; Bierwagen, K.; Brandt, S.; Busza, W.; Cali, I. A.; Demiragli, Z.; Di Matteo, L.; Gomez Ceballos, G.; Goncharov, M.; Hsu, D.; Iiyama, Y.; Innocenti, G. M.; Klute, M.; Kovalskyi, D.; Krajczar, K.; Lai, Y. S.; Lee, Y.-J.; Levin, A.; Luckey, P. D.; Marini, A. C.; Mcginn, C.; Mironov, C.; Narayanan, S.; Niu, X.; Paus, C.; Roland, C.; Roland, G.; Salfeld-Nebgen, J.; Stephans, G. S. F.; Sumorok, K.; Tatar, K.; Varma, M.; Velicanu, D.; Veverka, J.; Wang, J.; Wang, T. W.; Wyslouch, B.; Yang, M.; Zhukova, V.; Benvenuti, A. C.; Chatterjee, R. M.; Evans, A.; Finkel, A.; Gude, A.; Hansen, P.; Kalafut, S.; Kao, S. C.; Kubota, Y.; Lesko, Z.; Mans, J.; Nourbakhsh, S.; Ruckstuhl, N.; Rusack, R.; Tambe, N.; Turkewitz, J.; Acosta, J. G.; Oliveros, S.; Avdeeva, E.; Bartek, R.; Bloom, K.; Claes, D. R.; Dominguez, A.; Fangmeier, C.; Gonzalez Suarez, R.; Kamalieddin, R.; Kravchenko, I.; Malta Rodrigues, A.; Meier, F.; Monroy, J.; Siado, J. E.; Snow, G. R.; Stieger, B.; Alyari, M.; Dolen, J.; George, J.; Godshalk, A.; Harrington, C.; Iashvili, I.; Kaisen, J.; Kharchilava, A.; Kumar, A.; Parker, A.; Rappoccio, S.; Roozbahani, B.; Alverson, G.; Barberis, E.; Baumgartel, D.; Hortiangtham, A.; Massironi, A.; Morse, D. M.; Nash, D.; Orimoto, T.; Teixeira De Lima, R.; Trocino, D.; Wang, R.-J.; Wood, D.; Bhattacharya, S.; Hahn, K. A.; Kubik, A.; Kumar, A.; Low, J. F.; Mucia, N.; Odell, N.; Pollack, B.; Schmitt, M. H.; Sung, K.; Trovato, M.; Velasco, M.; Dev, N.; Hildreth, M.; Hurtado Anampa, K.; Jessop, C.; Karmgard, D. J.; Kellams, N.; Lannon, K.; Marinelli, N.; Meng, F.; Mueller, C.; Musienko, Y.; Planer, M.; Reinsvold, A.; Ruchti, R.; Smith, G.; Taroni, S.; Wayne, M.; Wolf, M.; Woodard, A.; Alimena, J.; Antonelli, L.; Brinson, J.; Bylsma, B.; Durkin, L. S.; Flowers, S.; Francis, B.; Hart, A.; Hill, C.; Hughes, R.; Ji, W.; Liu, B.; Luo, W.; Puigh, D.; Winer, B. L.; Wulsin, H. W.; Cooperstein, S.; Driga, O.; Elmer, P.; Hardenbrook, J.; Hebda, P.; Lange, D.; Luo, J.; Marlow, D.; Medvedeva, T.; Mei, K.; Mooney, M.; Olsen, J.; Palmer, C.; Piroué, P.; Stickland, D.; Tully, C.; Zuranski, A.; Malik, S.; Barker, A.; Barnes, V. E.; Folgueras, S.; Gutay, L.; Jha, M. K.; Jones, M.; Jung, A. W.; Jung, K.; Miller, D. H.; Neumeister, N.; Shi, X.; Sun, J.; Svyatkovskiy, A.; Wang, F.; Xie, W.; Xu, L.; Parashar, N.; Stupak, J.; Adair, A.; Akgun, B.; Chen, Z.; Ecklund, K. M.; Geurts, F. J. M.; Guilbaud, M.; Li, W.; Michlin, B.; Northup, M.; Padley, B. P.; Redjimi, R.; Roberts, J.; Rorie, J.; Tu, Z.; Zabel, J.; Betchart, B.; Bodek, A.; de Barbaro, P.; Demina, R.; Duh, Y. t.; Ferbel, T.; Galanti, M.; Garcia-Bellido, A.; Han, J.; Hindrichs, O.; Khukhunaishvili, A.; Lo, K. H.; Tan, P.; Verzetti, M.; Agapitos, A.; Chou, J. P.; Contreras-Campana, E.; Gershtein, Y.; Gómez Espinosa, T. A.; Halkiadakis, E.; Heindl, M.; Hidas, D.; Hughes, E.; Kaplan, S.; Kunnawalkam Elayavalli, R.; Kyriacou, S.; Lath, A.; Nash, K.; Saka, H.; Salur, S.; Schnetzer, S.; Sheffield, D.; Somalwar, S.; Stone, R.; Thomas, S.; Thomassen, P.; Walker, M.; Foerster, M.; Heideman, J.; Riley, G.; Rose, K.; Spanier, S.; Thapa, K.; Bouhali, O.; Celik, A.; Dalchenko, M.; De Mattia, M.; Delgado, A.; Dildick, S.; Eusebi, R.; Gilmore, J.; Huang, T.; Juska, E.; Kamon, T.; Mueller, R.; Pakhotin, Y.; Patel, R.; Perloff, A.; Perniè, L.; Rathjens, D.; Rose, A.; Safonov, A.; Tatarinov, A.; Ulmer, K. A.; Akchurin, N.; Cowden, C.; Damgov, J.; De Guio, F.; Dragoiu, C.; Dudero, P. R.; Faulkner, J.; Kunori, S.; Lamichhane, K.; Lee, S. W.; Libeiro, T.; Peltola, T.; Undleeb, S.; Volobouev, I.; Wang, Z.; Delannoy, A. G.; Greene, S.; Gurrola, A.; Janjam, R.; Johns, W.; Maguire, C.; Melo, A.; Ni, H.; Sheldon, P.; Tuo, S.; Velkovska, J.; Xu, Q.; Arenton, M. W.; Barria, P.; Cox, B.; Goodell, J.; Hirosky, R.; Ledovskoy, A.; Li, H.; Neu, C.; Sinthuprasith, T.; Sun, X.; Wang, Y.; Wolfe, E.; Xia, F.; Clarke, C.; Harr, R.; Karchin, P. E.; Lamichhane, P.; Sturdy, J.; Belknap, D. A.; Dasu, S.; Dodd, L.; Duric, S.; Gomber, B.; Grothe, M.; Herndon, M.; Hervé, A.; Klabbers, P.; Lanaro, A.; Levine, A.; Long, K.; Loveless, R.; Ojalvo, I.; Perry, T.; Polese, G.; Ruggles, T.; Savin, A.; Smith, N.; Smith, W. H.; Taylor, D.; Woods, N.; CMS Collaboration

2016-12-01

Results are presented of a search for heavy stable charged particles produced in proton-proton collisions at √{s }=13 TeV using a data sample corresponding to an integrated luminosity of 2.5 fb-1 collected in 2015 with the CMS detector at the CERN LHC. The search is conducted using signatures of anomalously high energy deposits in the silicon tracker and long time-of-flight measurements by the muon system. The data are consistent with the expected background, and upper limits are set on the cross sections for production of long-lived gluinos, top squarks, tau sleptons, and leptonlike long-lived fermions. These upper limits are equivalently expressed as lower limits on the masses of new states; the limits for gluinos, ranging up to 1610 GeV, are the most stringent to date. Limits on the cross sections for direct pair production of long-lived tau sleptons are also determined.

A randomized controlled trial of laparoscopic nissen fundoplication versus proton pump inhibitors for treatment of patients with chronic gastroesophageal reflux disease: One-year follow-up.

PubMed

Anvari, Mehran; Allen, Christopher; Marshall, John; Armstrong, David; Goeree, Ron; Ungar, Wendy; Goldsmith, Charles

2006-12-01

A randomized controlled trial conducted in patients with gastroesophageal reflux disease compared optimized medical therapy using proton pump inhibitor (n = 52) with laparoscopic Nissen fundoplication (n = 52). Patients were monitored for 1 year. The primary end point was frequency of gastroesophageal reflux dis-ease symptoms. Surgical patients had improved symptoms, pH control, and overall quality of life health index after surgery at 1 year compared with the medical group. The overall gastroesophageal reflux disease symptom score at 1 year was unchanged in the medical patients, but improved in the surgical patients. Fourteen patients in the medical arm experienced symptom relapse requiring titration of the proton pump inhibitor dose, but 6 had satisfactory symptom remission. No surgical patients required additional treatment for symptom control. Patients controlled on long-term proton pump inhibitor therapy for chronic gastroesophageal reflux disease are excellent surgical candidates and should experience improved symptom control after surgery at 1 year.

Free energy landscape for glucose condensation and dehydration reactions in dimethyl sulfoxide and the effects of solvent.

PubMed

Qian, Xianghong; Liu, Dajiang

2014-03-31

The mechanisms and free energy surfaces (FES) for the initial critical steps during proton-catalyzed glucose condensation and dehydration reactions were elucidated in dimethyl sulfoxide (DMSO) using Car-Parrinello molecular dynamics (CPMD) coupled with metadynamics (MTD) simulations. Glucose condensation reaction is initiated by protonation of C1--OH whereas dehydration reaction is initiated by protonation of C2--OH. The mechanisms in DMSO are similar to those in aqueous solution. The DMSO molecules closest to the C1--OH or C2--OH on glucose are directly involved in the reactions and act as proton acceptors during the process. However, the energy barriers are strongly solvent dependent. Moreover, polarization from the long-range electrostatic interaction affects the mechanisms and energetics of glucose reactions. Experimental measurements conducted in various DMSO/Water mixtures also show that energy barriers are solvent dependent in agreement with our theoretical results. Copyright © 2014 Elsevier Ltd. All rights reserved.

Semi-interpenetrating polymer network proton exchange membranes with narrow and well-connected hydrophilic channels

NASA Astrophysics Data System (ADS)

Fang, Chunliu; Toh, Xin Ni; Yao, Qiaofeng; Julius, David; Hong, Liang; Lee, Jim Yang

2013-03-01

Four series of semi-interpenetrating polymer network (SIPN) membranes are fabricated by thermally cross-linking aminated BPPO (brominated poly(2,6-dimethyl-1,4-phenylene oxide)) with different epoxide cross-linkers in the presence of sulfonated PPO (SPPO). The cross-link structure and hydrophobicity are found to impact the membrane morphology strongly - smaller and more hydrophobic cross-links form narrow and well-connected hydrophilic channels whereas bulky and less hydrophobic cross-links form wide but less-connected hydrophilic channels. The membranes of the former can support facile proton transport and suppress methanol crossover to result in higher proton conductivity and lower methanol permeability than the membranes of the latter. The membranes are also fabricated into membrane electrode assemblies (MEAs) and tested in single-stack direct methanol fuel cells (DMFCs). It is found that some of these SIPN membranes can surpass Nafion® 117 in maximum power density, demonstrating their potential as a proton exchange membrane (PEM) for the DMFCs.

Search for high-mass new phenomena in the dilepton final state using proton-proton collisions at √{ s} = 13TeV with the ATLAS detector

NASA Astrophysics Data System (ADS)

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L.; Massa, I.; Massa, L.; Mastrandrea, P.; Mastroberardino, A.; Masubuchi, T.; Mättig, P.; Mattmann, J.; Maurer, J.; Maxfield, S. J.; Maximov, D. A.; Mazini, R.; Mazza, S. M.; Mc Fadden, N. C.; Mc Goldrick, G.; Mc Kee, S. P.; McCarn, A.; McCarthy, R. L.; McCarthy, T. G.; McClymont, L. I.; McDonald, E. F.; McFarlane, K. W.; McFayden, J. A.; McHedlidze, G.; McMahon, S. J.; McPherson, R. A.; Medinnis, M.; Meehan, S.; Mehlhase, S.; Mehta, A.; Meier, K.; Meineck, C.; Meirose, B.; Melini, D.; Mellado Garcia, B. R.; Melo, M.; Meloni, F.; Mengarelli, A.; Menke, S.; Meoni, E.; Mergelmeyer, S.; Mermod, P.; Merola, L.; Meroni, C.; Merritt, F. S.; Messina, A.; Metcalfe, J.; Mete, A. S.; Meyer, C.; Meyer, C.; Meyer, J.-P.; Meyer, J.; Meyer Zu Theenhausen, H.; Miano, F.; Middleton, R. P.; Miglioranzi, S.; Mijović, L.; Mikenberg, G.; Mikestikova, M.; Mikuž, M.; Milesi, M.; Milic, A.; Miller, D. W.; Mills, C.; Milov, A.; Milstead, D. A.; Minaenko, A. A.; Minami, Y.; Minashvili, I. A.; Mincer, A. I.; Mindur, B.; Mineev, M.; Ming, Y.; Mir, L. M.; Mistry, K. P.; Mitani, T.; Mitrevski, J.; Mitsou, V. A.; Miucci, A.; Miyagawa, P. S.; Mjörnmark, J. U.; Moa, T.; Mochizuki, K.; Mohapatra, S.; Molander, S.; Moles-Valls, R.; Monden, R.; Mondragon, M. C.; Mönig, K.; Monk, J.; Monnier, E.; Montalbano, A.; Montejo Berlingen, J.; Monticelli, F.; Monzani, S.; Moore, R. W.; Morange, N.; Moreno, D.; Moreno Llácer, M.; Morettini, P.; Mori, D.; Mori, T.; Morii, M.; Morinaga, M.; Morisbak, V.; Moritz, S.; Morley, A. K.; Mornacchi, G.; Morris, J. D.; Mortensen, S. S.; Morvaj, L.; Mosidze, M.; Moss, J.; Motohashi, K.; Mount, R.; Mountricha, E.; Mouraviev, S. V.; Moyse, E. J. W.; Muanza, S.; Mudd, R. D.; Mueller, F.; Mueller, J.; Mueller, R. S. P.; Mueller, T.; Muenstermann, D.; Mullen, P.; Mullier, G. A.; Munoz Sanchez, F. J.; Murillo Quijada, J. A.; Murray, W. J.; Musheghyan, H.; Muškinja, M.; Myagkov, A. G.; Myska, M.; Nachman, B. P.; Nackenhorst, O.; Nagai, K.; Nagai, R.; Nagano, K.; Nagasaka, Y.; Nagata, K.; Nagel, M.; Nagy, E.; Nairz, A. M.; Nakahama, Y.; Nakamura, K.; Nakamura, T.; Nakano, I.; Namasivayam, H.; Naranjo Garcia, R. F.; Narayan, R.; Narrias Villar, D. I.; Naryshkin, I.; Naumann, T.; Navarro, G.; Nayyar, R.; Neal, H. A.; Nechaeva, P. Yu.; Neep, T. J.; Nef, P. D.; Negri, A.; Negrini, M.; Nektarijevic, S.; Nellist, C.; Nelson, A.; Nemecek, S.; Nemethy, P.; Nepomuceno, A. A.; Nessi, M.; Neubauer, M. S.; Neumann, M.; Neves, R. M.; Nevski, P.; Newman, P. R.; Nguyen, D. H.; Nguyen Manh, T.; Nickerson, R. B.; Nicolaidou, R.; Nielsen, J.; Nikiforov, A.; Nikolaenko, V.; Nikolic-Audit, I.; Nikolopoulos, K.; Nilsen, J. K.; Nilsson, P.; Ninomiya, Y.; Nisati, A.; Nisius, R.; Nobe, T.; Nodulman, L.; Nomachi, M.; Nomidis, I.; Nooney, T.; Norberg, S.; Nordberg, M.; Norjoharuddeen, N.; Novgorodova, O.; Nowak, S.; Nozaki, M.; Nozka, L.; Ntekas, K.; Nurse, E.; Nuti, F.; O'Grady, F.; O'Neil, D. C.; O'Rourke, A. A.; O'Shea, V.; Oakham, F. G.; Oberlack, H.; Obermann, T.; Ocariz, J.; Ochi, A.; Ochoa, I.; Ochoa-Ricoux, J. P.; Oda, S.; Odaka, S.; Ogren, H.; Oh, A.; Oh, S. H.; Ohm, C. C.; Ohman, H.; Oide, H.; Okawa, H.; Okumura, Y.; Okuyama, T.; Olariu, A.; Oleiro Seabra, L. F.; Olivares Pino, S. A.; Oliveira Damazio, D.; Olszewski, A.; Olszowska, J.; Onofre, A.; Onogi, K.; Onyisi, P. U. E.; Oreglia, M. J.; Oren, Y.; Orestano, D.; Orlando, N.; Orr, R. S.; Osculati, B.; Ospanov, R.; Otero Y Garzon, G.; Otono, H.; Ouchrif, M.; Ould-Saada, F.; Ouraou, A.; Oussoren, K. P.; Ouyang, Q.; Owen, M.; Owen, R. E.; Ozcan, V. E.; Ozturk, N.; Pachal, K.; Pacheco Pages, A.; Pacheco Rodriguez, L.; Padilla Aranda, C.; Pagáčová, M.; Pagan Griso, S.; Paige, F.; Pais, P.; Pajchel, K.; Palacino, G.; Palestini, S.; Palka, M.; Pallin, D.; Palma, A.; Panagiotopoulou, E. St.; Pandini, C. E.; Panduro Vazquez, J. G.; Pani, P.; Panitkin, S.; Pantea, D.; Paolozzi, L.; Papadopoulou, Th. D.; Papageorgiou, K.; Paramonov, A.; Paredes Hernandez, D.; Parker, A. J.; Parker, M. A.; Parker, K. A.; Parodi, F.; Parsons, J. A.; Parzefall, U.; Pascuzzi, V. R.; Pasqualucci, E.; Passaggio, S.; Pastore, Fr.; Pásztor, G.; Pataraia, S.; Pater, J. R.; Pauly, T.; Pearce, J.; Pearson, B.; Pedersen, L. E.; Pedersen, M.; Pedraza Lopez, S.; Pedro, R.; Peleganchuk, S. V.; Pelikan, D.; Penc, O.; Peng, C.; Peng, H.; Penwell, J.; Peralva, B. S.; Perego, M. M.; Perepelitsa, D. V.; Perez Codina, E.; Perini, L.; Pernegger, H.; Perrella, S.; Peschke, R.; Peshekhonov, V. D.; Peters, K.; Peters, R. F. Y.; Petersen, B. A.; Petersen, T. C.; Petit, E.; Petridis, A.; Petridou, C.; Petroff, P.; Petrolo, E.; Petrov, M.; Petrucci, F.; Pettersson, N. E.; Peyaud, A.; Pezoa, R.; Phillips, P. W.; Piacquadio, G.; Pianori, E.; Picazio, A.; Piccaro, E.; Piccinini, M.; Pickering, M. A.; Piegaia, R.; Pilcher, J. E.; Pilkington, A. D.; Pin, A. W. J.; Pinamonti, M.; Pinfold, J. L.; Pingel, A.; Pires, S.; Pirumov, H.; Pitt, M.; Plazak, L.; Pleier, M.-A.; Pleskot, V.; Plotnikova, E.; Plucinski, P.; Pluth, D.; Poettgen, R.; Poggioli, L.; Pohl, D.; Polesello, G.; Poley, A.; Policicchio, A.; Polifka, R.; Polini, A.; Pollard, C. S.; Polychronakos, V.; Pommès, K.; Pontecorvo, L.; Pope, B. G.; Popeneciu, G. A.; Popovic, D. S.; Poppleton, A.; Pospisil, S.; Potamianos, K.; Potrap, I. N.; Potter, C. J.; Potter, C. T.; Poulard, G.; Poveda, J.; Pozdnyakov, V.; Pozo Astigarraga, M. E.; Pralavorio, P.; Pranko, A.; Prell, S.; Price, D.; Price, L. E.; Primavera, M.; Prince, S.; Proissl, M.; Prokofiev, K.; Prokoshin, F.; Protopopescu, S.; Proudfoot, J.; Przybycien, M.; Puddu, D.; Purohit, M.; Puzo, P.; Qian, J.; Qin, G.; Qin, Y.; Quadt, A.; Quayle, W. B.; Queitsch-Maitland, M.; Quilty, D.; Raddum, S.; Radeka, V.; Radescu, V.; Radhakrishnan, S. K.; Radloff, P.; Rados, P.; Ragusa, F.; Rahal, G.; Raine, J. A.; Rajagopalan, S.; Rammensee, M.; Rangel-Smith, C.; Ratti, M. G.; Rauscher, F.; Rave, S.; Ravenscroft, T.; Ravinovich, I.; Raymond, M.; Read, A. L.; Readioff, N. P.; Reale, M.; Rebuzzi, D. M.; Redelbach, A.; Redlinger, G.; Reece, R.; Reeves, K.; Rehnisch, L.; Reichert, J.; Reisin, H.; Rembser, C.; Ren, H.; Rescigno, M.; Resconi, S.; Rettie, S.; Rezanova, O. L.; Reznicek, P.; Rezvani, R.; Richter, R.; Richter, S.; Richter-Was, E.; Ricken, O.; Ridel, M.; Rieck, P.; Riegel, C. J.; Rieger, J.; Rifki, O.; Rijssenbeek, M.; Rimoldi, A.; Rimoldi, M.; Rinaldi, L.; Ristić, B.; Ritsch, E.; Riu, I.; Rizatdinova, F.; Rizvi, E.; Rizzi, C.; Robertson, S. H.; Robichaud-Veronneau, A.; Robinson, D.; Robinson, J. E. M.; Robson, A.; Roda, C.; Rodina, Y.; Rodriguez Perez, A.; Rodriguez Rodriguez, D.; Roe, S.; Rogan, C. S.; Røhne, O.; Romaniouk, A.; Romano, M.; Romano Saez, S. M.; Romero Adam, E.; Rompotis, N.; Ronzani, M.; Roos, L.; Ros, E.; Rosati, S.; Rosbach, K.; Rose, P.; Rosenthal, O.; Rosien, N.-A.; Rossetti, V.; Rossi, E.; Rossi, L. P.; Rosten, J. H. N.; Rosten, R.; Rotaru, M.; Roth, I.; Rothberg, J.; Rousseau, D.; Royon, C. R.; Rozanov, A.; Rozen, Y.; Ruan, X.; Rubbo, F.; Rudolph, M. S.; Rühr, F.; Ruiz-Martinez, A.; Rurikova, Z.; Rusakovich, N. A.; Ruschke, A.; Russell, H. L.; Rutherfoord, J. P.; Ruthmann, N.; Ryabov, Y. F.; Rybar, M.; Rybkin, G.; Ryu, S.; Ryzhov, A.; Rzehorz, G. F.; Saavedra, A. F.; Sabato, G.; Sacerdoti, S.; Sadrozinski, H. F.-W.; Sadykov, R.; Safai Tehrani, F.; Saha, P.; Sahinsoy, M.; Saimpert, M.; Saito, T.; Sakamoto, H.; Sakurai, Y.; Salamanna, G.; Salamon, A.; Salazar Loyola, J. E.; Salek, D.; Sales de Bruin, P. H.; Salihagic, D.; Salnikov, A.; Salt, J.; Salvatore, D.; Salvatore, F.; Salvucci, A.; Salzburger, A.; Sammel, D.; Sampsonidis, D.; Sanchez, A.; Sánchez, J.; Sanchez Martinez, V.; Sandaker, H.; Sandbach, R. L.; Sander, H. G.; Sandhoff, M.; Sandoval, C.; Sandstroem, R.; Sankey, D. P. C.; Sannino, M.; Sansoni, A.; Santoni, C.; Santonico, R.; Santos, H.; Santoyo Castillo, I.; Sapp, K.; Sapronov, A.; Saraiva, J. G.; Sarrazin, B.; Sasaki, O.; Sasaki, Y.; Sato, K.; Sauvage, G.; Sauvan, E.; Savage, G.; Savard, P.; Sawyer, C.; Sawyer, L.; Saxon, J.; Sbarra, C.; Sbrizzi, A.; Scanlon, T.; Scannicchio, D. A.; Scarcella, M.; Scarfone, V.; Schaarschmidt, J.; Schacht, P.; Schachtner, B. M.; Schaefer, D.; Schaefer, R.; Schaeffer, J.; Schaepe, S.; Schaetzel, S.; Schäfer, U.; Schaffer, A. C.; Schaile, D.; Schamberger, R. D.; Scharf, V.; Schegelsky, V. A.; Scheirich, D.; Schernau, M.; Schiavi, C.; Schier, S.; Schillo, C.; Schioppa, M.; Schlenker, S.; Schmidt-Sommerfeld, K. R.; Schmieden, K.; Schmitt, C.; Schmitt, S.; Schmitz, S.; Schneider, B.; Schnoor, U.; Schoeffel, L.; Schoening, A.; Schoenrock, B. D.; Schopf, E.; Schott, M.; Schovancova, J.; Schramm, S.; Schreyer, M.; Schuh, N.; Schulte, A.; Schultens, M. J.; Schultz-Coulon, H.-C.; Schulz, H.; Schumacher, M.; Schumm, B. A.; Schune, Ph.; Schwartzman, A.; Schwarz, T. A.; Schwegler, Ph.; Schweiger, H.; Schwemling, Ph.; Schwienhorst, R.; Schwindling, J.; Schwindt, T.; Sciolla, G.; Scuri, F.; Scutti, F.; Searcy, J.; Seema, P.; Seidel, S. C.; Seiden, A.; Seifert, F.; Seixas, J. M.; Sekhniaidze, G.; Sekhon, K.; Sekula, S. J.; Seliverstov, D. M.; Semprini-Cesari, N.; Serfon, C.; Serin, L.; Serkin, L.; Sessa, M.; Seuster, R.; Severini, H.; Sfiligoj, T.; Sforza, F.; Sfyrla, A.; Shabalina, E.; Shaikh, N. W.; Shan, L. Y.; Shang, R.; Shank, J. T.; Shapiro, M.; Shatalov, P. B.; Shaw, K.; Shaw, S. M.; Shcherbakova, A.; Shehu, C. Y.; Sherwood, P.; Shi, L.; Shimizu, S.; Shimmin, C. O.; Shimojima, M.; Shiyakova, M.; Shmeleva, A.; Shoaleh Saadi, D.; Shochet, M. J.; Shojaii, S.; Shrestha, S.; Shulga, E.; Shupe, M. A.; Sicho, P.; Sickles, A. M.; Sidebo, P. E.; Sidiropoulou, O.; Sidorov, D.; Sidoti, A.; Siegert, F.; Sijacki, Dj.; Silva, J.; Silverstein, S. B.; Simak, V.; Simard, O.; Simic, Lj.; Simion, S.; Simioni, E.; Simmons, B.; Simon, D.; Simon, M.; Sinervo, P.; Sinev, N. B.; Sioli, M.; Siragusa, G.; Sivoklokov, S. Yu.; Sjölin, J.; Skinner, M. B.; Skottowe, H. P.; Skubic, P.; Slater, M.; Slavicek, T.; Slawinska, M.; Sliwa, K.; Slovak, R.; Smakhtin, V.; Smart, B. H.; Smestad, L.; Smiesko, J.; Smirnov, S. Yu.; Smirnov, Y.; Smirnova, L. N.; Smirnova, O.; Smith, M. N. K.; Smith, R. W.; Smizanska, M.; Smolek, K.; Snesarev, A. A.; Snyder, S.; Sobie, R.; Socher, F.; Soffer, A.; Soh, D. A.; Sokhrannyi, G.; Solans Sanchez, C. A.; Solar, M.; Soldatov, E. Yu.; Soldevila, U.; Solodkov, A. A.; Soloshenko, A.; Solovyanov, O. V.; Solovyev, V.; Sommer, P.; Son, H.; Song, H. Y.; Sood, A.; Sopczak, A.; Sopko, V.; Sorin, V.; Sosa, D.; Sotiropoulou, C. L.; Soualah, R.; Soukharev, A. M.; South, D.; Sowden, B. C.; Spagnolo, S.; Spalla, M.; Spangenberg, M.; Spanò, F.; Sperlich, D.; Spettel, F.; Spighi, R.; Spigo, G.; Spiller, L. A.; Spousta, M.; St. Denis, R. D.; Stabile, A.; Stamen, R.; Stamm, S.; Stanecka, E.; Stanek, R. W.; Stanescu, C.; Stanescu-Bellu, M.; Stanitzki, M. M.; Stapnes, S.; Starchenko, E. A.; Stark, G. H.; Stark, J.; Staroba, P.; Starovoitov, P.; Stärz, S.; Staszewski, R.; Steinberg, P.; Stelzer, B.; Stelzer, H. J.; Stelzer-Chilton, O.; Stenzel, H.; Stewart, G. A.; Stillings, J. A.; Stockton, M. C.; Stoebe, M.; Stoicea, G.; Stolte, P.; Stonjek, S.; Stradling, A. R.; Straessner, A.; Stramaglia, M. E.; Strandberg, J.; Strandberg, S.; Strandlie, A.; Strauss, M.; Strizenec, P.; Ströhmer, R.; Strom, D. M.; Stroynowski, R.; Strubig, A.; Stucci, S. A.; Stugu, B.; Styles, N. A.; Su, D.; Su, J.; Subramaniam, R.; Suchek, S.; Sugaya, Y.; Suk, M.; Sulin, V. V.; Sultansoy, S.; Sumida, T.; Sun, S.; Sun, X.; Sundermann, J. E.; Suruliz, K.; Susinno, G.; Sutton, M. R.; Suzuki, S.; Svatos, M.; Swiatlowski, M.; Sykora, I.; Sykora, T.; Ta, D.; Taccini, C.; Tackmann, K.; Taenzer, J.; Taffard, A.; Tafirout, R.; Taiblum, N.; Takai, H.; Takashima, R.; Takeshita, T.; Takubo, Y.; Talby, M.; Talyshev, A. A.; Tan, K. G.; Tanaka, J.; Tanaka, R.; Tanaka, S.; Tannenwald, B. B.; Tapia Araya, S.; Tapprogge, S.; Tarem, S.; Tartarelli, G. F.; Tas, P.; Tasevsky, M.; Tashiro, T.; Tassi, E.; Tavares Delgado, A.; Tayalati, Y.; Taylor, A. C.; Taylor, G. N.; Taylor, P. T. E.; Taylor, W.; Teischinger, F. A.; Teixeira-Dias, P.; Temming, K. K.; Temple, D.; Ten Kate, H.; Teng, P. K.; Teoh, J. J.; Tepel, F.; Terada, S.; Terashi, K.; Terron, J.; Terzo, S.; Testa, M.; Teuscher, R. J.; Theveneaux-Pelzer, T.; Thomas, J. P.; Thomas-Wilsker, J.; Thompson, E. N.; Thompson, P. D.; Thompson, A. S.; Thomsen, L. A.; Thomson, E.; Thomson, M.; Tibbetts, M. J.; Ticse Torres, R. E.; Tikhomirov, V. O.; Tikhonov, Yu. A.; Timoshenko, S.; Tipton, P.; Tisserant, S.; Todome, K.; Todorov, T.; Todorova-Nova, S.; Tojo, J.; Tokár, S.; Tokushuku, K.; Tolley, E.; Tomlinson, L.; Tomoto, M.; Tompkins, L.; Toms, K.; Tong, B.; Torrence, E.; Torres, H.; Torró Pastor, E.; Toth, J.; Touchard, F.; Tovey, D. R.; Trefzger, T.; Tricoli, A.; Trigger, I. M.; Trincaz-Duvoid, S.; Tripiana, M. F.; Trischuk, W.; Trocmé, B.; Trofymov, A.; Troncon, C.; Trottier-McDonald, M.; Trovatelli, M.; Truong, L.; Trzebinski, M.; Trzupek, A.; Tseng, J. C.-L.; Tsiareshka, P. V.; Tsipolitis, G.; Tsirintanis, N.; Tsiskaridze, S.; Tsiskaridze, V.; Tskhadadze, E. G.; Tsui, K. M.; Tsukerman, I. I.; Tsulaia, V.; Tsuno, S.; Tsybychev, D.; Tudorache, A.; Tudorache, V.; Tuna, A. N.; Tupputi, S. A.; Turchikhin, S.; Turecek, D.; Turgeman, D.; Turra, R.; Turvey, A. J.; Tuts, P. M.; Tyndel, M.; Ucchielli, G.; Ueda, I.; Ughetto, M.; Ukegawa, F.; Unal, G.; Undrus, A.; Unel, G.; Ungaro, F. C.; Unno, Y.; Unverdorben, C.; Urban, J.; Urquijo, P.; Urrejola, P.; Usai, G.; Usanova, A.; Vacavant, L.; Vacek, V.; Vachon, B.; Valderanis, C.; Valdes Santurio, E.; Valencic, N.; Valentinetti, S.; Valero, A.; Valery, L.; Valkar, S.; Vallecorsa, S.; Valls Ferrer, J. A.; van den Wollenberg, W.; van der Deijl, P. C.; van der Geer, R.; van der Graaf, H.; van Eldik, N.; van Gemmeren, P.; van Nieuwkoop, J.; van Vulpen, I.; van Woerden, M. C.; Vanadia, M.; Vandelli, W.; Vanguri, R.; Vaniachine, A.; Vankov, P.; Vardanyan, G.; Vari, R.; Varnes, E. W.; Varol, T.; Varouchas, D.; Vartapetian, A.; Varvell, K. E.; Vasquez, J. G.; Vazeille, F.; Vazquez Schroeder, T.; Veatch, J.; Veloce, L. M.; Veloso, F.; Veneziano, S.; Ventura, A.; Venturi, M.; Venturi, N.; Venturini, A.; Vercesi, V.; Verducci, M.; Verkerke, W.; Vermeulen, J. C.; Vest, A.; Vetterli, M. C.; Viazlo, O.; Vichou, I.; Vickey, T.; Vickey Boeriu, O. E.; Viehhauser, G. H. A.; Viel, S.; Vigani, L.; Vigne, R.; Villa, M.; Villaplana Perez, M.; Vilucchi, E.; Vincter, M. G.; Vinogradov, V. B.; Vittori, C.; Vivarelli, I.; Vlachos, S.; Vlasak, M.; Vogel, M.; Vokac, P.; Volpi, G.; Volpi, M.; von der Schmitt, H.; von Toerne, E.; Vorobel, V.; Vorobev, K.; Vos, M.; Voss, R.; Vossebeld, J. H.; Vranjes, N.; Vranjes Milosavljevic, M.; Vrba, V.; Vreeswijk, M.; Vuillermet, R.; Vukotic, I.; Vykydal, Z.; Wagner, P.; Wagner, W.; Wahlberg, H.; Wahrmund, S.; Wakabayashi, J.; Walder, J.; Walker, R.; Walkowiak, W.; Wallangen, V.; Wang, C.; Wang, C.; Wang, F.; Wang, H.; Wang, H.; Wang, J.; Wang, J.; Wang, K.; Wang, R.; Wang, S. M.; Wang, T.; Wang, T.; Wang, W.; Wang, X.; Wanotayaroj, C.; Warburton, A.; Ward, C. P.; Wardrope, D. R.; Washbrook, A.; Watkins, P. M.; Watson, A. T.; Watson, M. F.; Watts, G.; Watts, S.; Waugh, B. M.; Webb, S.; Weber, M. S.; Weber, S. W.; Webster, J. S.; Weidberg, A. R.; Weinert, B.; Weingarten, J.; Weiser, C.; Weits, H.; Wells, P. S.; Wenaus, T.; Wengler, T.; Wenig, S.; Wermes, N.; Werner, M.; Werner, M. D.; Werner, P.; Wessels, M.; Wetter, J.; Whalen, K.; Whallon, N. L.; Wharton, A. M.; White, A.; White, M. J.; White, R.; Whiteson, D.; Wickens, F. J.; Wiedenmann, W.; Wielers, M.; Wienemann, P.; Wiglesworth, C.; Wiik-Fuchs, L. A. M.; Wildauer, A.; Wilk, F.; Wilkens, H. G.; Williams, H. H.; Williams, S.; Willis, C.; Willocq, S.; Wilson, J. A.; Wingerter-Seez, I.; Winklmeier, F.; Winston, O. J.; Winter, B. T.; Wittgen, M.; Wittkowski, J.; Wolter, M. W.; Wolters, H.; Worm, S. D.; Wosiek, B. K.; Wotschack, J.; Woudstra, M. J.; Wozniak, K. W.; Wu, M.; Wu, M.; Wu, S. L.; Wu, X.; Wu, Y.; Wyatt, T. R.; Wynne, B. M.; Xella, S.; Xu, D.; Xu, L.; Yabsley, B.; Yacoob, S.; Yakabe, R.; Yamaguchi, D.; Yamaguchi, Y.; Yamamoto, A.; Yamamoto, S.; Yamanaka, T.; Yamauchi, K.; Yamazaki, Y.; Yan, Z.; Yang, H.; Yang, H.; Yang, Y.; Yang, Z.; Yao, W.-M.; Yap, Y. C.; Yasu, Y.; Yatsenko, E.; Yau Wong, K. H.; Ye, J.; Ye, S.; Yeletskikh, I.; Yen, A. L.; Yildirim, E.; Yorita, K.; Yoshida, R.; Yoshihara, K.; Young, C.; Young, C. J. S.; Youssef, S.; Yu, D. R.; Yu, J.; Yu, J. M.; Yu, J.; Yuan, L.; Yuen, S. P. Y.; Yusuff, I.; Zabinski, B.; Zaidan, R.; Zaitsev, A. M.; Zakharchuk, N.; Zalieckas, J.; Zaman, A.; Zambito, S.; Zanello, L.; Zanzi, D.; Zeitnitz, C.; Zeman, M.; Zemla, A.; Zeng, J. C.; Zeng, Q.; Zengel, K.; Zenin, O.; Ženiš, T.; Zerwas, D.; Zhang, D.; Zhang, F.; Zhang, G.; Zhang, H.; Zhang, J.; Zhang, L.; Zhang, R.; Zhang, R.; Zhang, X.; Zhang, Z.; Zhao, X.; Zhao, Y.; Zhao, Z.; Zhemchugov, A.; Zhong, J.; Zhou, B.; Zhou, C.; Zhou, L.; Zhou, L.; Zhou, M.; Zhou, N.; Zhu, C. G.; Zhu, H.; Zhu, J.; Zhu, Y.; Zhuang, X.; Zhukov, K.; Zibell, A.; Zieminska, D.; Zimine, N. I.; Zimmermann, C.; Zimmermann, S.; Zinonos, Z.; Zinser, M.; Ziolkowski, M.; Živković, L.; Zobernig, G.; Zoccoli, A.; Zur Nedden, M.; Zwalinski, L.; Atlas Collaboration

2016-10-01

A search is conducted for both resonant and non-resonant high-mass new phenomena in dielectron and dimuon final states. The search uses 3.2fb-1 of proton-proton collision data, collected at √{ s} = 13TeV by the ATLAS experiment at the LHC in 2015. The dilepton invariant mass is used as the discriminating variable. No significant deviation from the Standard Model prediction is observed; therefore limits are set on the signal model parameters of interest at 95% credibility level. Upper limits are set on the cross-section times branching ratio for resonances decaying to dileptons, and the limits are converted into lower limits on the resonance mass, ranging between 2.74 TeV and 3.36 TeV, depending on the model. Lower limits on the ℓℓqq contact interaction scale are set between 16.7 TeV and 25.2 TeV, also depending on the model.

Search for long-lived charged particles in proton-proton collisions at s = 13 TeV

DOE PAGES

Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; ...

2016-12-07

Results are presented of a search for heavy stable charged particles produced in proton-proton collisions at √s = 13 TeV using a data sample corresponding to an integrated luminosity of 2.5 fb –1 collected in 2015 with the CMS detector at the CERN LHC. The search is conducted using signatures of anomalously high energy deposits in the silicon tracker and long time-of-flight measurements by the muon system. The data are consistent with the expected background, and upper limits are set on the cross sections for production of long-lived gluinos, top squarks, tau sleptons, and lepton-like long-lived fermions. These upper limitsmore » are equivalently expressed as lower limits on the masses of new states; the limits for gluinos, ranging up to 1610 GeV, are the most stringent to date. Furthermore, limits on the cross sections for direct pair production of long-lived tau sleptons are also determined.« less

An integrated field-effect microdevice for monitoring membrane transport in Xenopus laevis oocytes via lateral proton diffusion.

PubMed

Schaffhauser, Daniel Felix; Patti, Monica; Goda, Tatsuro; Miyahara, Yuji; Forster, Ian Cameron; Dittrich, Petra Stephanie

2012-01-01

An integrated microdevice for measuring proton-dependent membrane activity at the surface of Xenopus laevis oocytes is presented. By establishing a stable contact between the oocyte vitelline membrane and an ion-sensitive field-effect (ISFET) sensor inside a microperfusion channel, changes in surface pH that are hypothesized to result from facilitated proton lateral diffusion along the membrane were detected. The solute diffusion barrier created between the sensor and the active membrane area allowed detection of surface proton concentration free from interference of solutes in bulk solution. The proposed sensor mechanism was verified by heterologously expressing membrane transport proteins and recording changes in surface pH during application of the specific substrates. Experiments conducted on two families of phosphate-sodium cotransporters (SLC20 & SLC34) demonstrated that it is possible to detect phosphate transport for both electrogenic and electroneutral isoforms and distinguish between transport of different phosphate species. Furthermore, the transport activity of the proton/amino acid cotransporter PAT1 assayed using conventional whole cell electrophysiology correlated well with changes in surface pH, confirming the ability of the system to detect activity proportional to expression level.

Effects of CO2 adsorption on proton migration on a hydrated ZrO2 surface: an ab initio molecular dynamics study.

PubMed

Sato, Ryuhei; Shibuta, Yasushi; Shimojo, Fuyuki; Yamaguchi, Shu

2017-08-02

Hydration reactions on a carbonate-terminated cubic ZrO 2 (110) surface were analyzed using ab initio molecular dynamics (AIMD) simulations. After hydration reactions, carbonates were still present on the surface at 500 K. However, these carbonates are very weak conjugate bases and only act as steric hindrance in proton hopping processes between acidic chemisorbed H 2 O molecules (Zr-OH 2 ) and monodentate hydroxyl groups (Zr-OH - ). Similar to a carbonate-free hydrated surface, Zr-OH 2 , Zr-OH - , and polydentate hydroxyl groups ([double bond splayed left]OH + ) were observed, while the ratio of acidic Zr-OH 2 was significantly larger than that on the carbonate-free hydrated surface. A thermodynamic discussion and bond property analysis reveal that CO 2 adsorption significantly decreases the basicity of surface oxide ions ([double bond splayed left]O), whereas the acidity of Zr-OH 2 is not affected. As a result, protons released from [double bond splayed left]OH + react with Zr-OH - to form Zr-OH 2 , leading to a deficiency of proton acceptor sites, which decreases the proton conductivity by the hopping mechanism.

Nickel-Catalyzed Proton-Deuterium Exchange (HDX) Procedures for Glycosidic Linkage Analysis of Complex Carbohydrates.

PubMed

Price, Neil P J; Hartman, Trina M; Vermillion, Karl E

2015-07-21

The structural analysis of complex carbohydrates typically requires the assignment of three parameters: monosaccharide composition, the position of glycosidic linkages between monosaccharides, and the position and nature of noncarbohydrate substituents. The glycosidic linkage positions are often determined by permethylation analysis, but this can be complicated by high viscosity or poor solubility, resulting in under-methylation. This is a drawback because an under-methylated position may be misinterpreted as the erroneous site of a linkage or substituent. Here, we describe an alternative approach to linkage analysis that makes use of a nonreversible deuterium exchange of C-H protons on the carbohydrate backbone. The exchange reaction is conducted in deuterated water catalyzed by Raney nickel, and results in the selective exchange of C-H protons adjacent to free hydroxyl groups. Hence, the position of the residual C-H protons is indicative of the position of glycosidic linkages or other substituents and can be readily assigned by heteronuclear single quantum coherence-nuclear magnetic resonance (HSQC-NMR) or, following suitable derivatization, by gas chromatography-mass spectroscopy (GC/MS) analysis. Moreover, because the only changes to the parent sugar are proton/deuterium exchanges, the composition and linkage analysis can be determined in a single step.

Advanced Hybrid Membranes for Next Generation PEMFC Automotive Applications.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Herring, Andrew M; Motz, Andrew R; Kuo, Mei-Chen

The objective of this proposal is to fabricate a low cost high performance hybrid inorganic/polymer membrane that has a proton area specific resistance (ASR) < 0.02 ohm cm2 at the operating temperature of an automotive fuel cell stack (95 - 120°C) at low inlet RH <50% with good mechanical and chemical durability. Additionally the membrane will be optimized for low hydrogen and oxygen crossover with high electrical ASR at all temperatures and adequate proton ASR at lower temperatures. We also seek to gain valuable insights into rapid proton transport at the limit of proton hydration. Additional research will be performedmore » to incorporate the membrane into a 50 cm2 membrane electrode assembly (MEA). The materials at the start of this project are at a TRL of 2, as we have shown that they have proton conductivity under high and dry conditions, but we have not yet consistently shown that they will function in an operational fuel cell. At the project’s end the materials will be at a TRL of 4 and will be integrated into an MEA, demonstrating that they can function with electrodes as a single fuel cell.« less

Hydrocarbon sensors and materials therefor

DOEpatents

Pham, Ai Quoc; Glass, Robert S.

2000-01-01

An electrochemical hydrocarbon sensor and materials for use in sensors. A suitable proton conducting electrolyte and catalytic materials have been found for specific application in the detection and measurement of non-methane hydrocarbons. The sensor comprises a proton conducting electrolyte sandwiched between two electrodes. At least one of the electrodes is covered with a hydrocarbon decomposition catalyst. Two different modes of operation for the hydrocarbon sensors can be used: equilibrium versus non-equilibrium measurements and differential catalytic. The sensor has particular application for on-board monitoring of automobile exhaust gases to evaluate the performance of catalytic converters. In addition, the sensor can be utilized in monitoring any process where hydrocarbons are exhausted, for instance, industrial power plants. The sensor is low cost, rugged, sensitive, simple to fabricate, miniature, and does not suffer cross sensitivities.

Thermal conductivity measurements of proton-heated warm dense aluminum

NASA Astrophysics Data System (ADS)

McKelvey, A.; Kemp, G.; Sterne, P.; Fernandez, A.; Shepherd, R.; Marinak, M.; Link, A.; Collins, G.; Sio, H.; King, J.; Freeman, R.; Hua, R.; McGuffey, C.; Kim, J.; Beg, F.; Ping, Y.

2017-10-01

We present the first thermal conductivity measurements of warm dense aluminum at 0.5-2.7 g/cc and 2-10 eV, using a recently developed platform of differential heating. A temperature gradient is induced in a Au/Al dual-layer target by proton heating, and subsequent heat flow from the hotter Au to the Al rear surface is detected by two simultaneous time-resolved diagnostics. A systematic data set allows for constraining both thermal conductivity and equation-of-state models. Simulations using Purgatorio model or Sesame S27314 for Al thermal conductivity and LEOS for Au/Al release equation-of-state show good agreement with data after 15 ps. Predictions by other models, such Lee-More, Sesame 27311 and 29373, are outside of experimental error bars. Discrepancy still exists at early time 0-15 ps, likely due to non-equilibrium conditions. (Y. Ping et al. Phys. Plasmas, 2015, A. Mckelvey, et al. Sci. Reports 2017). This work was performed under the auspices of the DOE by LLNL under contract DE-AC52-07NA27344 with support from DOE OFES Early Career program and LLNL LDRD program.

Optomechanical characterization of proton-exchange membrane fuel cells

NASA Astrophysics Data System (ADS)

Jalani, Nikhil H.; Mizar, Shivananda P.; Choi, Pyoungho; Furlong, Cosme; Datta, Ravindra

2004-08-01

Nafion is widely used as the polymer electrolyte in proton exchange membrane (PEM) fuel cells. The properties that make the Nafion membrane indispensable are the combination of good water uptake, ion-exchange capacity, proton conductivity, gas permeability, and excellent electrochemical stability. The amount of water sorbed in the Nafion membrane is critical as the proton conductivity depends directly on the water content of the membrane which determines the fuel cell performance. The factors which affect the extent of the solvent uptake by Nafion are temperature, ion-exchange capacity, pretreatment of membrane, and the physical state of absorbing water, whether it is in liquid or vapor phase. The water sorption in the membrane is explained in terms of thermodynamic equilibrium of water in the vapor and absorption phases. As the membrane imbibes more water, the membrane matrix expands and exerts a pressure on the pore liquid which affects its chemical potential and limits extent of swelling. The extent of matrix expansion of the membranes depends on the elastic modulus, E, of the membrane, which directly affects the sorption. Hence, it is important to understand the variation of E for Nafion membrane with relative humidity (RH) and temperature. Optoelectronic holography (OEH) techniques are applied to perform quantitative, noninvasive, full field of view investigations to determine temperature and water activity dependence of E. The results obtained confirm that with the increase in temperature, E decreases and the membranes imbibes more water. Such results will allow optimization and realization of fuel cells with improved efficiency and performance.

Highly efficient sulfonated polybenzimidazole as a proton exchange membrane for microbial fuel cells

NASA Astrophysics Data System (ADS)

Singha, Shuvra; Jana, Tushar; Modestra, J. Annie; Naresh Kumar, A.; Mohan, S. Venkata

2016-06-01

Although microbial fuel cells (MFCs) represent a promising bio-energy technology with a dual advantage (i.e., electricity production and waste-water treatment), their low power densities and high installation costs are major impediments. To address these bottlenecks and replace highly expensive Nafion, which is a proton exchange membrane (PEM), the current study focuses for the first time on membranes made from an easily synthesizable and more economical oxy-polybenzimidazole (OPBI) and its sulfonated analogue (S-OPBI) as alternate PEMs in single-chambered MFCs. The S-OPBI membrane exhibits better properties, with high water uptake, ion exchange capacity (IEC) and proton conductivity and a comparatively smaller degree of swelling compared to Nafion. The membrane morphology is characterized by atomic force microscopy, and the bright and dark regions of the S-OPBI membrane reveals the formation of ionic domains in the matrix, forming continuous water nanochannels when doped with water. These water-filled nanochannels are responsible for faster proton conduction in S-OPBI than in Nafion; therefore, the power output in the MFC with S-OPBI as the PEM is higher than in other MFCs. The open circuit voltage (460 mV), current generation (2.27 mA) and power density profile (110 mW/m2) as a function of time, as well as the polarization curves, exhibits higher current and power density (87.8 mW/m2) with S-OPBI compared to Nafion as the PEM.

Asymmetric protonation of EmrE

PubMed Central

Morrison, Emma A.; Robinson, Anne E.; Liu, Yongjia

2015-01-01

The small multidrug resistance transporter EmrE is a homodimer that uses energy provided by the proton motive force to drive the efflux of drug substrates. The pKa values of its “active-site” residues—glutamate 14 (Glu14) from each subunit—must be poised around physiological pH values to efficiently couple proton import to drug export in vivo. To assess the protonation of EmrE, pH titrations were conducted with 1H-15N TROSY-HSQC nuclear magnetic resonance (NMR) spectra. Analysis of these spectra indicates that the Glu14 residues have asymmetric pKa values of 7.0 ± 0.1 and 8.2 ± 0.3 at 45°C and 6.8 ± 0.1 and 8.5 ± 0.2 at 25°C. These pKa values are substantially increased compared with typical pKa values for solvent-exposed glutamates but are within the range of published Glu14 pKa values inferred from the pH dependence of substrate binding and transport assays. The active-site mutant, E14D-EmrE, has pKa values below the physiological pH range, consistent with its impaired transport activity. The NMR spectra demonstrate that the protonation states of the active-site Glu14 residues determine both the global structure and the rate of conformational exchange between inward- and outward-facing EmrE. Thus, the pKa values of the asymmetric active-site Glu14 residues are key for proper coupling of proton import to multidrug efflux. However, the results raise new questions regarding the coupling mechanism because they show that EmrE exists in a mixture of protonation states near neutral pH and can interconvert between inward- and outward-facing forms in multiple different protonation states. PMID:26573622

Note: Optimization of the numerical data analysis for conductivity percolation studies of drying moist porous systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moscicki, J. K.; Sokolowska, D.; Dziob, D.

2014-02-15

A simplified data analysis protocol, for dielectric spectroscopy use to study conductivity percolation in dehydrating granular media is discussed. To enhance visibility of the protonic conductivity contribution to the dielectric loss spectrum, detrimental effects of either low-frequency dielectric relaxation or electrode polarization are removed. Use of the directly measurable monofrequency dielectric loss factor rather than estimated DC conductivity to parameterize the percolation transition substantially reduces the analysis work and time.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Storey, Robson, F.; Mauritz, Kenneth, A.; Patton, Derek, L.

The overall objective of this project was the development and evaluation of novel hydrocarbon fuel cell (FC) membranes that possess high temperature performance and long term chemical/mechanical durability in proton exchange membrane (PEM) fuel cells (FC). The major research theme was synthesis of aromatic hydrocarbon polymers of the poly(arylene ether sulfone) (PAES) type containing sulfonic acid groups tethered to the backbone via perfluorinated alkylene linkages and in some cases also directly attached to the phenylene groups along the backbone. Other research themes were the use of nitrogen-based heterocyclics instead of acid groups for proton conduction, which provides high temperature, lowmore » relative humidity membranes with high mechanical/thermal/chemical stability and pendant moieties that exhibit high proton conductivities in the absence of water, and synthesis of block copolymers consisting of a proton conducting block coupled to poly(perfluorinated propylene oxide) (PFPO) blocks. Accomplishments of the project were as follows: 1) establishment of a vertically integrated program of synthesis, characterization, and evaluation of FC membranes, 2) establishment of benchmark membrane performance data based on Nafion for comparison to experimental membrane performance, 3) development of a new perfluoroalkyl sulfonate monomer, N,N-diisopropylethylammonium 2,2-bis(p-hydroxyphenyl) pentafluoropropanesulfonate (HPPS), 4) synthesis of random and block copolymer membranes from HPPS, 5) synthesis of block copolymer membranes containing high-acid-concentration hydrophilic blocks consisting of HPPS and 3,3'-disulfonate-4,4'-dichlorodiphenylsulfone (sDCDPS), 6) development of synthetic routes to aromatic polymer backbones containing pendent 1H-1,2,3-triazole moieties, 7) development of coupling strategies to create phase-separated block copolymers between hydrophilic sulfonated prepolymers and commodity polymers such as PFPO, 8) establishment of basic performance properties of experimental membranes, 9) fabrication and FC performance testing of membrane electrode assemblies (MEA) from experimental membranes, and 10) measurement of ex situ and in situ membrane durability of experimental membranes. Although none of the experimental hydrocarbon membranes that issued from the project displayed proton conductivities that met DOE requirements, the project contributed to our basic understanding of membrane structure-property relationships in a number of key respects. An important finding of the benchmark studies is that physical degradation associated with humidity and temperature variations in the FC tend to open new fuel crossover pathways and act synergistically with chemical degradation to accelerate overall membrane degradation. Thus, for long term membrane survival and efficient fuel utilization, membranes must withstand internal stresses due to humidity and temperature changes. In this respect, rigid aromatic hydrocarbon fuel cell membranes, e.g. PAES, offer an advantage over un-modified Nafion membranes. The benchmark studies also showed that broadband dielectric spectroscopy is a potentially powerful tool in assessing shifts in the fundamental macromolecular dynamics caused by Nafion chemical degradation, and thus, this technique is of relevance in interrogating proton exchange membrane durability in fuel cells and macromolecular dynamics as coupled to proton migration, which is of fundamental relevance in proton exchange membranes in fuel cells. A key finding from the hydrocarbon membrane synthesis effort was that rigid aromatic polymers containing isolated ion exchange groups tethered tightly to the backbone (short tether), such as HPPS, provide excellent mechanical and durability properties but do not provide sufficient conductivity, in either random or block configuration, when used as the sole ion exchange monomer. However, we continue to hypothesize that longer tethers, and tethered groups spaced more closely within the hydrophilic chain elements of the polymer, will yield highly conductive materials with excellent mechanical properties. Another key finding is the superior performance of PAES membranes upon being subjected to open circuit voltage (OCV) testing. Throughout the course of the experiment, OCV for the PAES not only stayed higher but also decayed at a much lower rate, which is attributed to better dimensional stability and improved mechanical and gas barrier properties. The rigid backbone reinforcement of PAES adds gas diffusion tortuosity that restricts membrane degradation and OCV loss due to reduced fuel crossover. The overall results of creep, contractile stress and mechanical tensile tests confirm the conclusion that degraded MEAs of PAES membrane can handle stress and are more likely to be more durable in a fuel cell, even after subjected to 62h of OCV degradation.« less

Characterization of the microbunch time structure of proton pencil beams at a clinical treatment facility.

PubMed

Petzoldt, J; Roemer, K E; Enghardt, W; Fiedler, F; Golnik, C; Hueso-González, F; Helmbrecht, S; Kormoll, T; Rohling, H; Smeets, J; Werner, T; Pausch, G

2016-03-21

Proton therapy is an advantageous treatment modality compared to conventional radiotherapy. In contrast to photons, charged particles have a finite range and can thus spare organs at risk. Additionally, the increased ionization density in the so-called Bragg peak close to the particle range can be utilized for maximum dose deposition in the tumour volume. Unfortunately, the accuracy of the therapy can be affected by range uncertainties, which have to be covered by additional safety margins around the treatment volume. A real-time range and dose verification is therefore highly desired and would be key to exploit the major advantages of proton therapy. Prompt gamma rays, produced in nuclear reactions between projectile and target nuclei, can be used to measure the proton's range. The prompt gamma-ray timing (PGT) method aims at obtaining this information by determining the gamma-ray emission time along the proton path using a conventional time-of-flight detector setup. First tests at a clinical accelerator have shown the feasibility to observe range shifts of about 5 mm at clinically relevant doses. However, PGT spectra are smeared out by the bunch time spread. Additionally, accelerator related proton bunch drifts against the radio frequency have been detected, preventing a potential range verification. At OncoRay, first experiments using a proton bunch monitor (PBM) at a clinical pencil beam have been conducted. Elastic proton scattering at a hydrogen-containing foil could be utilized to create a coincident proton-proton signal in two identical PBMs. The selection of coincident events helped to suppress uncorrelated background. The PBM setup was used as time reference for a PGT detector to correct for potential bunch drifts. Furthermore, the corrected PGT data were used to image an inhomogeneous phantom. In a further systematic measurement campaign, the bunch time spread and the proton transmission rate were measured for several beam energies between 69 and 225 MeV as well as for variable momentum limiting slit openings. We conclude that the usage of a PBM increases the robustness of the PGT method in clinical conditions and that the obtained data will help to create reliable range verification procedures in clinical routine.

Influence of High-Energy Proton Irradiation on β-Ga2O3 Nanobelt Field-Effect Transistors.

PubMed

Yang, Gwangseok; Jang, Soohwan; Ren, Fan; Pearton, Stephen J; Kim, Jihyun

2017-11-22

The robust radiation resistance of wide-band gap materials is advantageous for space applications, where the high-energy particle irradiation deteriorates the performance of electronic devices. We report on the effects of proton irradiation of β-Ga 2 O 3 nanobelts, whose energy band gap is ∼4.85 eV at room temperature. Back-gated field-effect transistor (FET) based on exfoliated quasi-two-dimensional β-Ga 2 O 3 nanobelts were exposed to a 10 MeV proton beam. The proton-dose- and time-dependent characteristics of the radiation-damaged FETs were systematically analyzed. A 73% decrease in the field-effect mobility and a positive shift of the threshold voltage were observed after proton irradiation at a fluence of 2 × 10 15 cm -2 . Greater radiation-induced degradation occurs in the conductive channel of the β-Ga 2 O 3 nanobelt than at the contact between the metal and β-Ga 2 O 3 . The on/off ratio of the exfoliated β-Ga 2 O 3 FETs was maintained even after proton doses up to 2 × 10 15 cm -2 . The radiation-induced damage in the β-Ga 2 O 3 -based FETs was significantly recovered after rapid thermal annealing at 500 °C. The outstanding radiation durability of β-Ga 2 O 3 renders it a promising building block for space applications.

Thermal conductivity profile determination in proton-irradiated ZrC by spatial and frequency scanning thermal wave methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jensen, C.; Department of Mechanical and Aerospace Engineering, Utah State University, Logan, Utah 84322; Chirtoc, M.

2013-10-07

Using complementary thermal wave methods, the irradiation damaged region of zirconium carbide (ZrC) is characterized by quantifiably profiling the thermophysical property degradation. The ZrC sample was irradiated by a 2.6 MeV proton beam at 600 °C to a dose of 1.75 displacements per atom. Spatial scanning techniques including scanning thermal microscopy (SThM), lock-in infrared thermography (lock-in IRT), and photothermal radiometry (PTR) were used to directly map the in-depth profile of thermal conductivity on a cross section of the ZrC sample. The advantages and limitations of each system are discussed and compared, finding consistent results from all techniques. SThM provides themore » best resolution finding a very uniform thermal conductivity envelope in the damaged region measuring ∼52 ± 2 μm deep. Frequency-based scanning PTR provides quantification of the thermal parameters of the sample using the SThM measured profile to provide validation of a heating model. Measured irradiated and virgin thermal conductivities are found to be 11.9 ± 0.5 W m{sup −1} K{sup −1} and 26.7 ±1 W m{sup −1} K{sup −1}, respectively. A thermal resistance evidenced in the frequency spectra of the PTR results was calculated to be (1.58 ± 0.1) × 10{sup −6} m{sup 2} K W{sup −1}. The measured thermal conductivity values compare well with the thermal conductivity extracted from the SThM calibrated signal and the spatially scanned PTR. Combined spatial and frequency scanning techniques are shown to provide a valuable, complementary combination for thermal property characterization of proton-irradiated ZrC. Such methodology could be useful for other studies of ion-irradiated materials.« less

Philosophy of voltage-gated proton channels

PubMed Central

DeCoursey, Thomas E.; Hosler, Jonathan

2014-01-01

In this review, voltage-gated proton channels are considered from a mainly teleological perspective. Why do proton channels exist? What good are they? Why did they go to such lengths to develop several unique hallmark properties such as extreme selectivity and ΔpH-dependent gating? Why is their current so minuscule? How do they manage to be so selective? What is the basis for our belief that they conduct H+ and not OH–? Why do they exist in many species as dimers when the monomeric form seems to work quite well? It is hoped that pondering these questions will provide an introduction to these channels and a way to logically organize their peculiar properties as well as to understand how they are able to carry out some of their better-established biological functions. PMID:24352668

Anhydrous state proton and lithium ion conducting solid polymer electrolytes based on sulfonated bisphenol-A-poly(arylene ethers)

NASA Astrophysics Data System (ADS)

Guha Thakurta, Soma

Sulfonated polymer based solid polymer electrolytes (SPEs) have received considerable interest in recent years because of their wide variety of applications particularly in fuel cells, batteries, supercapacitors, and electrochromic devices. The present research was focused on three interrelated subtopics. First, two different bisphenol-A-poly(arylene ethers), polyetherimide (PEI) and polysulfone (PSU) were sulfonated by a post sulfonation method to various degrees of sulfonation, and their thermal and mechanical properties were examined. The effects of poly(arylene ether) chemical structure, reaction time, concentration, and types of sulfonating agents on sulfonation reaction were investigated. It was found that deactivation of bisphenol A unit caused by the electron withdrawing imide, retarded the sulfonation of PEI compared to PSU. Sulfonation conducted with a high concentration of sulfonating agent and/or prolonged reaction time exhibited evidence of degradation at the isopropylidene unit. The degradation occurred through the same mechanistic pathway with the two different sulfonating agents, chlorosulfonic acid (CSA) and trimethylsilyl chlorosulfonate (TMSCS). The degradation was faster with CSA than its silyl ester, TMSCS, and was evident even at low acid concentration. Second, novel anhydrous proton conducting solid polymer electrolytes (SPEs) were prepared by the incorporation of 1H-1,2,4-triazole (Taz) as a proton solvent in sulfonated polyetherimide (SPEI) matrix. The size, shape, and state of dispersion (crystal morphology) of triazole crystals in SPEI were examined as a function of degree of sulfonation and triazole concentration. Increasing sulfonic acid content caused reduction of triazole crystallite size, hence the depression of melting temperature and their uniform distribution throughout the sulfonated polymer matrix. The increased rate of structure diffusion within the smaller size crystals due to the improved molecular mobility contributed significantly to the anhydrous state proton conductivity. Third, a new category of single lithium ion conducting SPEs was developed by crosslinking a polyether epoxy, poly(ethylene glycol)diglicidyl ether (PEGDGE) (lithium ion solvent), in sulfonated polysulfone (SPSU) matrix. The effects of degree of sulfonation and electrolyte composition on ionic conductivity, thermal, and tensile properties of SPEs were investigated. It was found that ion-dipole interactions between lithium sulfonate (SO3Li) and PEGDGE were responsible for the reduction in size of the dispersed epoxy phase and increased thermal stability. Lithium sulfonate promoted compatibilization and also caused improvement in elongation at break. A low molecular weight electrolyte salt, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) was further dissolved in PEGDGE phase prior to its crosslinking in SPSU matrix, and the ionic conductivity and thermal properties were evaluated as a function of doping level. The ionic conductivity showed remarkable improvement compared to the undoped system.

Double perovskite cathodes for proton-conducting ceramic fuel cells: are they triple mixed ionic electronic conductors?

NASA Astrophysics Data System (ADS)

Téllez Lozano, Helena; Druce, John; Cooper, Samuel J.; Kilner, John A.

2017-12-01

18O and 2H diffusion has been investigated at a temperature of 300 °C in the double perovskite material PrBaCo2O5+δ (PBCO) in flowing air containing 200 mbar of 2H216O. Secondary ion mass spectrometry (SIMS) depth profiling of exchanged ceramics has shown PBCO still retains significant oxygen diffusivity ( 1.3 × 10-11 cm2s-1) at this temperature and that the presence of water (2H216O), gives rise to an enhancement of the surface exchange rate over that in pure oxygen by a factor of 3. The 2H distribution, as inferred from the 2H216O- SIMS signal, shows an apparent depth profile which could be interpreted as 2H diffusion. However, examination of the 3-D distribution of the signal shows it to be nonhomogeneous and probably related to the presence of hydrated layers in the interior walls of pores and is not due to proton diffusion. This suggests that PBCO acts mainly as an oxygen ion mixed conductor when used in PCFC devices, although the presence of a small amount of protonic conductivity cannot be discounted in these materials.

Phase Behavior and Conductivity of Phosphonated Block Copolymers Containing Ionic Liquids

NASA Astrophysics Data System (ADS)

Jung, Ha Young; Kim, Sung Yeon; Park, Moon Jeong

2015-03-01

As the focus on proton exchange fuel cells continues to escalate in the era of alternative energy systems, the rational design of sulfonated polymers has emerged as a key technique for enhancing device efficiency. While the sulfonic acid group guarantees high proton conductivity of membranes under humidified conditions, the growing need for high temperature operation has discouraged their practical uses in fuel cells. In this respect, phosphonated polymers have drawn intensive attention in recent years owing to their self-dissociation ability. In this study, we have synthesized a set of phosphonated block copolymers, poly(styrenephosphonate-methylbutylene) (PSP- b - PMB), by varying phosphonation level (PL). A wide variety of self-assembled morphologies, i.e., disordered, lamellar, hexagonally perforated lamellae and hexagonally packed cylindrical phases, were observed with PL. Remarkably, upon comparing the morphology of PSP- b-PMB and that of sulfonated analog, we found distinctly dissimilar domain sizes at the same molecular weight and composition. A range of ionic liquids (ILs) were incorporated into the PSP- b-PMB block copolymers and their ion transport properties were examined. It has been revealed that the degree of confinement of ionic phases (domain size) impacts the ion mobility and proton dissociation efficiency of IL-containing polymers.

Durable and self-hydrating tungsten carbide-based composite polymer electrolyte membrane fuel cells.

PubMed

Zheng, Weiqing; Wang, Liang; Deng, Fei; Giles, Stephen A; Prasad, Ajay K; Advani, Suresh G; Yan, Yushan; Vlachos, Dionisios G

2017-09-04

Proton conductivity of the polymer electrolyte membranes in fuel cells dictates their performance and requires sufficient water management. Here, we report a simple, scalable method to produce well-dispersed transition metal carbide nanoparticles. We demonstrate that these, when added as an additive to the proton exchange Nafion membrane, provide significant enhancement in power density and durability over 100 hours, surpassing both the baseline Nafion and platinum-containing recast Nafion membranes. Focused ion beam/scanning electron microscope tomography reveals the key membrane degradation mechanism. Density functional theory exposes that OH• and H• radicals adsorb more strongly from solution and reactions producing OH• are significantly more endergonic on tungsten carbide than on platinum. Consequently, tungsten carbide may be a promising catalyst in self-hydrating crossover gases while retarding desorption of and capturing free radicals formed at the cathode, resulting in enhanced membrane durability.The proton conductivity of polymer electrolyte membranes in fuel cells dictates their performance, but requires sufficient water management. Here, the authors report a simple method to produce well-dispersed transition metal carbide nanoparticles as additives to enhance the performance of Nafion membranes in fuel cells.

Effect of irradiation with MeV protons and electrons on the conductivity compensation and photoluminescence of moderately doped p-4H-SiC (CVD)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kozlovski, V. V.; Lebedev, A. A., E-mail: shura.lebe@mail.ioffe.ru; Bogdanova, E. V.

The compensation of moderately doped p-4H-SiC samples grown by the chemical vapor deposition (CVD) method under irradiation with 0.9-MeV electrons and 15-MeV protons is studied. The experimentally measured carrier removal rates are 1.2–1.6 cm{sup –1} for electrons and 240–260 cm{sup –1} for protons. The dependence of the concentration of uncompensated acceptors and donors, measured in the study, demonstrates a linear decrease with increasing irradiation dose to the point of complete compensation. This run of the dependence shows that compensation of the samples is due to the transition of carriers to deep centers formed by primary radiation-induced defects. It is demonstratedmore » that, in contrast to n-SiC (CVD), primary defects in the carbon sublattice of moderately doped p-SiC (CVD) only cannot account for the compensation process. In p-SiC, either primary defects in the silicon sublattice, or defects in both sublattices are responsible for conductivity compensation. Also, photoluminescence spectra are examined in relation to the irradiation dose.« less

Dynamical onset of superconductivity and retention of magnetic fields in cooling neutron stars

NASA Astrophysics Data System (ADS)

Ho, Wynn C. G.; Andersson, Nils; Graber, Vanessa

2017-12-01

A superconductor of paired protons is thought to form in the core of neutron stars soon after their birth. Minimum energy conditions suggest magnetic flux is expelled from the superconducting region due to the Meissner effect, such that the neutron star core is largely devoid of magnetic fields for some nuclear equation of state and proton pairing models. We show via neutron star cooling simulations that the superconducting region expands faster than flux is expected to be expelled because cooling timescales are much shorter than timescales of magnetic field diffusion. Thus magnetic fields remain in the bulk of the neutron star core for at least 106-107yr . We estimate the size of flux free regions at 107yr to be ≲100 m for a magnetic field of 1011G and possibly smaller for stronger field strengths. For proton pairing models that are narrow, magnetic flux may be completely expelled from a thin shell of approximately the above size after 105yr . This shell may insulate lower conductivity outer layers, where magnetic fields can diffuse and decay faster, from fields maintained in the highly conducting deep core.

Sulfonated poly(ether sulfone)s containing pyridine moiety for PEMFC.

PubMed

Jang, Hohyoun; Islam, Md Monirul; Lim, Youngdon; Hossain, Md Awlad; Cho, Younggil; Joo, Hyunho; Kim, Whangi; Jeon, Heung-Seok

2014-10-01

Sulfonated poly(ether sulfone)s with varied degree of sulfonation (DS) were prepared via post-sulfonation of synthesized pyridine based poly(ether sulfone) (PPES) using concentrated sulfuric acid as sulfonating agent. The DS was varied with different mole ratio of 4,4'-(2,2-diphenylethenylidene)diphenol, DHTPE in the polymer unit. PPES copolymers were synthesized by direct polycondensation of pyridine unit with bis-(4-fluorophenyl)-sulfone, 4, 4'-sulfonyldiphenol and DHTPE. The structure of the resulting PPES copolymer membranes with different sulfonated units were studied by 1H NMR spectroscopy and thermogravimetric analysis (TGA). Sorption experiments were conducted to observe the interaction of sulfonated polymer with water. The ion exchange capacity (IEC) and proton conductivity were evaluated according to the increase of DS. The water uptake (WU) of the resulting membranes was in the range of 17-58%, compared to that of Nafion 211 28%. The membranes provided proton conductivities of 65-95 mS/cm in contrast to 103 mS/cm of Nafion 211.

Hydrogen Research for Spaceport and Space-Based Applications: Hydrogen Production, Storage, and Transport. Part 3

NASA Technical Reports Server (NTRS)

Anderson, Tim; Balaban, Canan

2008-01-01

The activities presented are a broad based approach to advancing key hydrogen related technologies in areas such as fuel cells, hydrogen production, and distributed sensors for hydrogen-leak detection, laser instrumentation for hydrogen-leak detection, and cryogenic transport and storage. Presented are the results from research projects, education and outreach activities, system and trade studies. The work will aid in advancing the state-of-the-art for several critical technologies related to the implementation of a hydrogen infrastructure. Activities conducted are relevant to a number of propulsion and power systems for terrestrial, aeronautics and aerospace applications. Hydrogen storage and in-space hydrogen transport research focused on developing and verifying design concepts for efficient, safe, lightweight liquid hydrogen cryogenic storage systems. Research into hydrogen production had a specific goal of further advancing proton conducting membrane technology in the laboratory at a larger scale. System and process trade studies evaluated the proton conducting membrane technology, specifically, scale-up issues.

Proton therapy - Present and future.

PubMed

Mohan, Radhe; Grosshans, David

2017-01-15

In principle, proton therapy offers a substantial clinical advantage over conventional photon therapy. This is because of the unique depth-dose characteristics of protons, which can be exploited to achieve significant reductions in normal tissue doses proximal and distal to the target volume. These may, in turn, allow escalation of tumor doses and greater sparing of normal tissues, thus potentially improving local control and survival while at the same time reducing toxicity and improving quality of life. Protons, accelerated to therapeutic energies ranging from 70 to 250MeV, typically with a cyclotron or a synchrotron, are transported to the treatment room where they enter the treatment head mounted on a rotating gantry. The initial thin beams of protons are spread laterally and longitudinally and shaped appropriately to deliver treatments. Spreading and shaping can be achieved by electro-mechanical means to treat the patients with "passively-scattered proton therapy" (PSPT) or using magnetic scanning of thin "beamlets" of protons of a sequence of initial energies. The latter technique can be used to treat patients with optimized intensity modulated proton therapy (IMPT), the most powerful proton modality. Despite the high potential of proton therapy, the clinical evidence supporting the broad use of protons is mixed. It is generally acknowledged that proton therapy is safe, effective and recommended for many types of pediatric cancers, ocular melanomas, chordomas and chondrosarcomas. Although promising results have been and continue to be reported for many other types of cancers, they are based on small studies. Considering the high cost of establishing and operating proton therapy centers, questions have been raised about their cost effectiveness. General consensus is that there is a need to conduct randomized trials and/or collect outcomes data in multi-institutional registries to unequivocally demonstrate the advantage of protons. Treatment planning and plan evaluation of PSPT and IMPT require special considerations compared to the processes used for photon treatment planning. The differences in techniques arise from the unique physical properties of protons but are also necessary because of the greater vulnerability of protons to uncertainties, especially from inter- and intra-fractional variations in anatomy. These factors must be considered in designing as well as evaluating treatment plans. In addition to anatomy variations, other sources of uncertainty in dose delivered to the patient include the approximations and assumptions of models used for computing dose distributions for planning of treatments. Furthermore, the relative biological effectiveness (RBE) of protons is simplistically assumed to have a constant value of 1.1. In reality, the RBE is variable and a complex function of the energy of protons, dose per fraction, tissue and cell type, end point, etc. These uncertainties, approximations and current technological limitations of proton therapy may limit the achievement of its true potential. Ongoing research is aimed at better understanding the consequences of the various uncertainties on proton therapy and reducing the uncertainties through image-guidance, adaptive radiotherapy, further study of biological properties of protons and the development of novel dose computation and optimization methods. However, residual uncertainties will remain in spite of the best efforts. To increase the resilience of dose distributions in the face of uncertainties and improve our confidence in dose distributions seen on treatment plans, robust optimization techniques are being developed and implemented. We assert that, with such research, proton therapy will be a commonly applied radiotherapy modality for most types of solid cancers in the near future. Copyright © 2016 Elsevier B.V. All rights reserved.

Synthesis of the diazonium (perfluoroalkyl) benzenesulfonimide monomer from Nafion monomer for proton exchange membrane fuel cells

NASA Astrophysics Data System (ADS)

Mei, Hua; D'Andrea, Dan; Nguyen, Tuyet-Trinh; Nworie, Chima

2014-02-01

One diazonium (perfluoroalkyl) benzenesulfonimide monomer, perfluoro-3, 6-dioxa-4-methyl-7-octene benzenesulfonyl imide, has been synthesized from Nafion monomer for the first time. With trifluorovinyl ether and diazonium precursors, the partially-fluorinated diazonium PFSI monomer can be polymerized and will provide chemically bonding with carbon electrode in proton exchange membrane fuel cells. A systematic study of the synthesis and characterization of this diazonium PFSI monomer has been conducted by varying reaction conditions. The optimized synthesis method has been established in the lab.

A comparative first-principles study of structural and electronic properties among memantine, amantadine and rimantadine

NASA Astrophysics Data System (ADS)

Middleton, Kirsten; Zhang, G. P.; Nichols, Michael R.; George, Thomas F.

2012-05-01

Memantine, amantadine and rimantadine are structurally derived from the same diamondoid, adamantane. These derivatives demonstrate therapeutic efficacy in human diseases: memantine for Alzheimer's disease and amantadine and rimantadine for influenza. In order to better understand some of the properties that distinguish these three compounds, we conduct first-principles calculations on their structure and electronic properties. Our results indicate that protonation has a significant effect on the dipole moment, where the dipole moment in protonated memantine is over eight times larger than in the deprotonated form.

Function of Proline Residues of MotA in Torque Generation by the Flagellar Motor of Escherichia coli

PubMed Central

Braun, Timothy F.; Poulson, Susan; Gully, Jonathan B.; Empey, J. Courtney; Van Way, Susan; Putnam, Angélica; Blair, David F.

1999-01-01

Bacterial flagellar motors obtain energy for rotation from the membrane gradient of protons or, in some species, sodium ions. The molecular mechanism of flagellar rotation is not understood. MotA and MotB are integral membrane proteins that function in proton conduction and are believed to form the stator of the motor. Previous mutational studies identified two conserved proline residues in MotA (Pro 173 and Pro 222 in the protein from Escherichia coli) and a conserved aspartic acid residue in MotB (Asp 32) that are important for function. Asp 32 of MotB probably forms part of the proton path through the motor. To learn more about the roles of the conserved proline residues of MotA, we examined motor function in Pro 173 and Pro 222 mutants, making measurements of torque at high load, speed at low and intermediate loads, and solvent-isotope effects (D2O versus H2O). Proton conduction by wild-type and mutant MotA-MotB channels was also assayed, by a growth defect that occurs upon overexpression. Several different mutations of Pro 173 reduced the torque of the motor under high load, and a few prevented motor rotation but still allowed proton flow through the MotA-MotB channels. These and other properties of the mutants suggest that Pro 173 has a pivotal role in coupling proton flow to motor rotation and is positioned in the channel near Asp 32 of MotB. Replacements of Pro 222 abolished function in all assays and were strongly dominant. Certain Pro 222 mutant proteins prevented swimming almost completely when expressed at moderate levels in wild-type cells. This dominance might be caused by rotor-stator jamming, because it was weaker when FliG carried a mutation believed to increase rotor-stator clearance. We propose a mechanism for torque generation, in which specific functions are suggested for the proline residues of MotA and Asp32 of MotB. PMID:10348868

Supercritical fluid in the mantle transition zone deduced from H-D interdiffusion of wadsleyite

NASA Astrophysics Data System (ADS)

Sun, Wei; Yoshino, Takashi; Sakamoto, Naoya; Yurimoto, Hisayoshi

2018-02-01

Knowledge of the distribution of water in the Earth's mantle is key to understanding the mantle convection and geochemical evolution of the Earth. As wadsleyite and ringwoodite can incorporate large amounts of water in their crystal structures, proton conduction has been invoked to account for the widespread conductive anomalies observed in the mantle wedge, where descending slab stagnates at the transition zone. However, there is a lot of controversy on whether proton conduction by itself is able to explain such anomalies, because of large discrepancy in the extent of the water effect deduced from previous electrical conductivity measurements on hydrous polycrystalline wadsleyite and ringwoodite. Here we report the hydrogen self-diffusion coefficient obtained from H-D interdiffusion experiments in wadsleyite single-crystal couples. Our results demonstrate that the effect of water on the electrical conductivity of wadsleyite is limited and hydrous wadsleyite by itself is unable to explain conductive anomalies in the transition zone. In contrast, the expected hydrogen effective diffusion does not allow the wide propagation of water between the stagnant slab and surrounding mantle, probably leading to persistence of local water saturation and continuous release of supercritical fluids at the stagnant slab roof on geological time scales. This phenomenon provides an alternative explanation for both the high-conductivity and seismic-velocity anomalies observed in the mantle wedge at the transition-zone depth.

Nanoporous palladium anode for direct ethanol solid oxide fuel cells with nanoscale proton-conducting ceramic electrolyte

NASA Astrophysics Data System (ADS)

Li, Yong; Wong, Lai Mun; Xie, Hanlin; Wang, Shijie; Su, Pei-Chen

2017-02-01

In this work, we demonstrate the operation of micro-solid oxide fuel cells (μ-SOFCs) with nanoscale proton-conducting Y-BaZrO3 (BZY) electrolyte to avoid the fuel crossover problem for direct ethanol fuel cells (DEFCs). The μ-SOFCs are operated with the direct utilisation of ethanol vapour as a fuel and Pd as anode at the temperature range of 300-400 °C. The nanoporous Pd anode is achieved by DC sputtering at high Ar pressure of 80 mTorr. The Pd-anode/BYZ-electrolyte/Pt-cathode cell show peak power densities of 72.4 mW/cm2 using hydrogen and 15.3 mW/cm2 using ethanol at 400 °C. No obvious carbon deposition is seen from XPS analysis after fuel cell test with ethanol fuel.

Ion-/proton-conducting apparatus and method

DOEpatents

Yates, Matthew [Penfield, NY; Liu, Dongxia [Rochester, NY

2011-05-17

A c-axis-oriented HAP thin film synthesized by seeded growth on a palladium hydrogen membrane substrate. An exemplary synthetic process includes electrochemical seeding on the substrate, and secondary and tertiary hydrothermal treatments under conditions that favor growth along c-axes and a-axes in sequence. By adjusting corresponding synthetic conditions, an HAP this film can be grown to a controllable thickness with a dense coverage on the underlying substrate. The thin films have relatively high proton conductivity under hydrogen atmosphere and high temperature conditions. The c-axis oriented films may be integrated into fuel cells for application in the intermediate temperature range of 200-600.degree. C. The electrochemical-hydrothermal deposition technique may be applied to create other oriented crystal materials having optimized properties, useful for separations and catalysis as well as electronic and electrochemical applications, electrochemical membrane reactors, and in chemical sensors.

Electrochemical performance of BaZr0.1Ce0.7Y0.1Yb0.1O3-δ electrolyte based proton-conducting SOFC solid oxide fuel cell with layered perovskite PrBaCo2O5+δ cathode

NASA Astrophysics Data System (ADS)

Ding, Hanping; Xie, Yuanyuan; Xue, Xingjian

2011-03-01

BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (BZCYYb) exhibits adequate protonic conductivity as well as sufficient chemical and thermal stability over a wide range of SOFC operating conditions, while layered perovskite PrBaCo2O5+δ (PBCO) has advanced electrochemical properties. This research fully takes advantage of these advanced properties and develops a novel protonic ceramic membrane fuel cell (PCMFC) of Ni-BZCYYb|BZCYYb|PBCO. The performance of the button cell was tested under intermediate-temperature range from 600 to 700 °C with humified H2 (∼3% H2O) as fuel and ambient air as oxidant. The results show that the open circuit potential of 0.983 V and the maximal power density of 490 mW cm-2 were achieved at 700 °C. By co-doping barium zirconate-cerate with Y and Yb, the conductivity of electrolyte was significantly improved. The polarization processes of the button cell were characterized using the complicated electrochemical impedance spectroscopy technique. The results indicate that the polarization resistances contributed from both charge migration processes and mass transfer processes increase with decreasing cell voltage loads. However the polarization resistance induced by mass transfer processes is negligible in the studied button cell.

Increases in intracellular pH facilitate endocytosis and decrease availability of voltage-gated proton channels in osteoclasts and microglia

PubMed Central

Sakai, Hiromu; Li, Guangshuai; Hino, Yoshiko; Moriura, Yoshie; Kawawaki, Junko; Sawada, Makoto; Kuno, Miyuki

2013-01-01

Voltage-gated proton channels (H+ channels) are highly proton-selective transmembrane pathways. Although the primary determinants for activation are the pH and voltage gradients across the membrane, the current amplitudes fluctuate often when these gradients are constant. The aim of this study was to investigate the role of the intracellular pH (pHi) in regulating the availability of H+ channels in osteoclasts and microglia. In whole-cell clamp recordings, the pHi was elevated after exposure to NH4Cl and returned to the control level after washout. However, the H+ channel conductance did not recover fully when the exposure was prolonged (>5 min). Similar results were observed in osteoclasts and microglia, but not in COS7 cells expressing a murine H+ channel gene (mVSOP). As other electrophysiological properties, like the gating kinetics and voltage dependence for activation, were unchanged, the decreases in the H+ channel conductance were probably due to the decreases in H+ channels available at the plasma membrane. The decreases in the H+ channel conductances were accompanied by reductions in the cell capacitance. Exposure to NH4Cl increased the uptake of the endocytosis marker FM1-43, substantiating the idea that pHi increases facilitated endocytosis. In osteoclasts, whose plasma membrane expresses V-ATPases and H+ channels, pHi increases by these H+-transferring molecules in part facilitated endocytosis. The endocytosis and decreases in the H+ channel conductance were reduced by dynasore, a dynamin blocker. These results suggest that pHi increases in osteoclasts and microglia decrease the numbers of H+ channels available at the plasma membrane through facilitation of dynamin-dependent endocytosis. PMID:24081153

Simulated infrared spectra of triflic acid during proton dissociation.

PubMed

Laflamme, Patrick; Beaudoin, Alexandre; Chapaton, Thomas; Spino, Claude; Soldera, Armand

2012-05-05

Vibrational analysis of triflic acid (TfOH) at different water uptakes was conducted. This molecule mimics the sulfonate end of the Nafion side-chain. As the proton leaves the sulfonic acid group, structural changes within the Nafion side-chain take place. They are revealed by signal shifts in the infrared spectrum. Molecular modeling is used to follow structural modifications that occur during proton dissociation. To confirm the accuracy of the proposed structures, infrared spectra were computed via quantum chemical modeling based on density functional theory. The requirement to use additional diffuse functions in the basis set is discussed. Comparison between simulated infrared spectra of 1 and 2 acid molecules with different water contents and experimental data was performed. An accurate description of infrared spectra for systems containing 2 TfOH was obtained. Copyright © 2012 Wiley Periodicals, Inc.

Polymeric hydrogen diffusion barrier, high-pressure storage tank so equipped, method of fabricating a storage tank and method of preventing hydrogen diffusion

DOEpatents

Lessing, Paul A [Idaho Falls, ID

2008-07-22

An electrochemically active hydrogen diffusion barrier which comprises an anode layer, a cathode layer, and an intermediate electrolyte layer, which is conductive to protons and substantially impermeable to hydrogen. A catalytic metal present in or adjacent to the anode layer catalyzes an electrochemical reaction that converts any hydrogen that diffuses through the electrolyte layer to protons and electrons. The protons and electrons are transported to the cathode layer and reacted to form hydrogen. The hydrogen diffusion barrier is applied to a polymeric substrate used in a storage tank to store hydrogen under high pressure. A storage tank equipped with the electrochemically active hydrogen diffusion barrier, a method of fabricating the storage tank, and a method of preventing hydrogen from diffusing out of a storage tank are also disclosed.

Polymeric hydrogen diffusion barrier, high-pressure storage tank so equipped, method of fabricating a storage tank and method of preventing hydrogen diffusion

DOEpatents

Lessing, Paul A.

2004-09-07

An electrochemically active hydrogen diffusion barrier which comprises an anode layer, a cathode layer, and an intermediate electrolyte layer, which is conductive to protons and substantially impermeable to hydrogen. A catalytic metal present in or adjacent to the anode layer catalyzes an electrochemical reaction that converts any hydrogen that diffuses through the electrolyte layer to protons and electrons. The protons and electrons are transported to the cathode layer and reacted to form hydrogen. The hydrogen diffusion barrier is applied to a polymeric substrate used in a storage tank to store hydrogen under high pressure. A storage tank equipped with the electrochemically active hydrogen diffusion barrier, a method of fabricating the storage tank, and a method of preventing hydrogen from diffusing out of a storage tank are also disclosed.

Mechanism and energetics by which glutamic acid 242 prevents leaks in cytochrome c oxidase.

PubMed

Kaila, Ville R I; Verkhovsky, Michael I; Hummer, Gerhard; Wikström, Mårten

2009-10-01

Cytochrome c oxidase (CcO) is the terminal enzyme of aerobic respiration. The energy released from the reduction of molecular oxygen to water is used to pump protons across the mitochondrial or bacterial membrane. The pump function introduces a mechanistic requirement of a valve that prevents protons from flowing backwards during the process. It was recently found that Glu-242, a key amino acid in transferring protons to be pumped across the membrane and to the site of oxygen reduction, fulfils the function of such a valve by preventing simultaneous contact to the pump site and to the proton-conducting D-channel (Kaila V.R.I. et al. Proc. Natl. Acad. Sci. USA 105, 2008). Here we have incorporated the valve model into the framework of the reaction mechanism. The function of the Glu valve is studied by exploring how the redox state of the surrounding metal centers, dielectric effects, and membrane potential, affects the energetics and leaks of this valve. Parallels are drawn between the dynamics of Glu-242 and the long-standing obscure difference between the metastable O(H) and stable O states of the binuclear center. Our model provides a suggestion for why reduction of the former state is coupled to proton translocation while reduction of the latter is not.

Three-dimensional Hybrid Simulation Study of Anisotropic Turbulence in the Proton Kinetic Regime

NASA Astrophysics Data System (ADS)

Vasquez, Bernard J.; Markovskii, Sergei A.; Chandran, Benjamin D. G.

2014-06-01

Three-dimensional numerical hybrid simulations with particle protons and quasi-neutralizing fluid electrons are conducted for a freely decaying turbulence that is anisotropic with respect to the background magnetic field. The turbulence evolution is determined by both the combined root-mean-square (rms) amplitude for fluctuating proton bulk velocity and magnetic field and by the ratio of perpendicular to parallel wavenumbers. This kind of relationship had been considered in the past with regard to interplanetary turbulence. The fluctuations nonlinearly evolve to a turbulent phase whose net wave vector anisotropy is usually more perpendicular than the initial one, irrespective of the initial ratio of perpendicular to parallel wavenumbers. Self-similar anisotropy evolution is found as a function of the rms amplitude and parallel wavenumber. Proton heating rates in the turbulent phase vary strongly with the rms amplitude but only weakly with the initial wave vector anisotropy. Even in the limit where wave vectors are confined to the plane perpendicular to the background magnetic field, the heating rate remains close to the corresponding case with finite parallel wave vector components. Simulation results obtained as a function of proton plasma to background magnetic pressure ratio β p in the range 0.1-0.5 show that the wave vector anisotropy also weakly depends on β p .

Perspective of Muon Production Target at J-PARC MLF MUSE

NASA Astrophysics Data System (ADS)

Makimura, Shunsuke; Matoba, Shiro; Kawamura, Naritoshi; Matsuzawa, Yukihiro; Tabe, Masato; Aoyagi, Hiroyuki; Kondo, Hiroto; Kobayashi, Yasuo; Fujimori, Hiroshi; Ikedo, Yutaka; Kadono, Ryosuke; Koda, Akihiro; Kojima, Kenji M.; Miyake, Yasuhiro; Nakamura, Jumpei G.; Oishi, Yu; Okabe, Hirotaka; Shimomura, Koichiro; Strasser, Patrick

A pulsed muon beam with unprecedented intensity will be generated by a 3-GeV 333-microA proton beam on a muon target made of 20-mm thick isotropic graphite at J-PARC MLF MUSE (Muon Science Establishment). The first muon beam was successfully generated on September 26th, 2008. Gradually upgrading the beam intensity, continuous 300-kW proton beam has been operated by a fixed target method without replacements till June of 2014. However, the lifetime of the fixed target was anticipated to be less than 1 year by the proton-irradiation damage of the graphite through 1-MW beam operation. To extend the lifetime, a muon rotating target, in which the radiation damage is distributed to a wider area, was installed in September of 2014, and continuous and stable operation has been successfully performed. Because the muon target becomes highly radioactive by the proton irradiation, the maintenance is conducted by remote handling in the Hot cell. In September of 2015, a scraper No. 1 to collimate the proton beam scattered by the target was replaced for further high-power beam operation. Recently, new developments on monitoring and maintenance of the muon target for higher power operation are in progress. In this article, perspective of muon production target at J-PARC MLF MUSE will be described.

Monte Carlo calculations in support of the commissioning of the Northeast Proton Therapy Center.

PubMed

Flanz, J; Paganetti, H

2003-12-01

Monte Carlo studies were conducted related to the design of the Northeast Proton Therapy Center (NPTC). These studies were also helpful for commissioning the beam delivery performance of the facility. The calculations included preventing proton leakage from the beam delivery nozzle, anomalies in the dose distributions and studies, which could influence future beam delivery techniques. Using simulations it was possible to reduce the proton leakage by over an order of magnitude, while minimizing the weight of the assembly. Interestingly, the thickness of the brass shielding has no influence on the secondary neutron radiation since the number of generated neutrons is almost independent of the amount of brass if the primary beam is completely stopped. Monte Carlo simulations are able to study the effect of small beam misalignments with respect to apertures in the nozzle. Such tolerances are very difficult to define experimentally. Studying the effects of nuclear interactions we showed that, if the dose distributions would be optimized theoretically using the primary proton dose alone, there would be about a 5 % dose increase at the proximal end of a SOBP. In radiobiology studies we found that the RBE at beam entrance increases due to the build-up of the secondary particle fluence.

Persistent activation of nuclear factor-kappa B and expression of pro-inflammatory cytokines in bone marrow cells after exposure of mice to protons

NASA Astrophysics Data System (ADS)

Rithidech, Kanokporn; Reungpatthanaphong, Paiboon; Honikel, Louise; Whorton, Elbert

Protons are the most abundant component of solar particle events (SPEs) in space. Information is limited on early-and late-occurring in vivo biological effects of exposure to protons at doses and dose rates that are similar to what astronauts encounter in space. We conducted a study series to fill this knowledge gap. We focused on the biological effects of 100 MeV/n protons, which are one of the most abundant types of protons induced during SPEs. We gave BALB/cJ mice a whole-body exposure to 0.5 or 1.0 Gy of 100 MeV/n protons, delivered at 0.5 or 1.0 cGy/min. These doses and dose rates of protons were selected because they are comparable to those of SPEs taking place in space. For each dose and dose rate of 100 MeV/n protons, mice exposed to 0 Gy of protons served as sham controls. Mice included in this study were also part of a study series conducted to examine the extent and the mechanisms involved in in vivo induction of genomic instability (expressed as late-occurring chromosome instability) by 100 MeV/n protons. Bone marrow (BM) cells were collected from groups of mice for analyses at different times post-exposure, i.e. early time-points (1.5, 3, and 24 hr) and late time-points (1 and 6 months). At each harvest time, there were five mice per treatment group. Several endpoints were used to investigate the biological effects of 100 MeV/n protons in BM cells from irradiated and sham control mice. The scope of this study was to determine the dose-rate effects of 0.5 Gy of 100 MeV/n protons in BM cells on the kinetics of nuclear factor-kappa B (NF-kappa B) activation and the expression of selected NF-kappa B target proteins known to be involved in inflammatory response, i.e. pro-inflammatory cytokines (TNF-alpha, IL-1 beta, and IL-6). Significantly high levels (p values ranging from p¡0.01 and p¡0.05) of activated NF-kappa B were observed in BM cells collected from irradiated mice, relative to those obtained from the corresponding sham controls, at all time-points included in the study, regardless of the dose rate of proton-irradiation. However, these increases were more pronounced when the higher dose rate (1.0 cGy/min) was used. The results indicated that NF-kappa B activation in BM cells persisted up to 6 months after exposure of mice to a single dose of 0.5 Gy of 100 MeV/n protons, delivered at the dose rates occurring in space. Further, significantly up-regulated levels of TNF-alpha were detected in BM cells of exposed mice (p values ranging from p¡0.01 and p¡0.05), compared to those in the corresponding sham controls, at all harvest times, in spite of the difference in dose rate of proton-irradiation. However, steady increases in the levels of IL-1 beta and IL-6 in BM cells of exposed mice over the levels in their sham controls across all time-points included in the study were detected only when a dose rate of 1.0 cGy/min was used. In contrast, with a dose rate of 0.5 cGy/min, significantly high expression levels of these two pro-inflammatory cytokines were consistently found in BM cells collected from exposed mice at late time-points only. In summary, our data provide important information for space flight missions because the findings of persistent activation of NF-kappa B and expression of pro-inflammatory cytokines suggest the occurrence of chronic inflammation after exposure of mice to 100 MeV/n protons that, in turn, may have an important impact on health outcome during space flights. Knowledge gained on the NF-kappa B pathway from this study could, therefore, be useful for planning countermeasure strategies to protect astronauts or space travelers in the space environment. Research funded by NASA Grant NNX07AP88G.

THE COUPLED EVOLUTION OF ELECTRONS AND IONS IN CORONAL MASS EJECTION-DRIVEN SHOCKS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Manchester IV, W. B.; Van der Holst, B.; Toth, G.

2012-09-01

We present simulations of coronal mass ejections (CMEs) performed with a new two-temperature coronal model developed at the University of Michigan, which is able to address the coupled thermodynamics of the electron and proton populations in the context of a single fluid. This model employs heat conduction for electrons, constant adiabatic index ({gamma} = 5/3), and includes Alfven wave pressure to accelerate the solar wind. The Wang-Sheeley-Arge empirical model is used to determine the Alfven wave pressure necessary to produce the observed bimodal solar wind speed. The Alfven waves are dissipated as they propagate from the Sun and heat protonsmore » on open magnetic field lines to temperatures above 2 MK. The model is driven by empirical boundary conditions that includes GONG magnetogram data to calculate the coronal field, and STEREO/EUVI observations to specify the density and temperature at the coronal boundary by the Differential Emission Measure Tomography method. With this model, we simulate the propagation of fast CMEs and study the thermodynamics of CME-driven shocks. Since the thermal speed of the electrons greatly exceeds the speed of the CME, only protons are directly heated by the shock. Coulomb collisions low in the corona couple the protons and electrons allowing heat exchange between the two species. However, the coupling is so brief that the electrons never achieve more than 10% of the maximum temperature of the protons. We find that heat is able to conduct on open magnetic field lines and rapidly propagates ahead of the CME to form a shock precursor of hot electrons.« less

Luminescence imaging of water during uniform-field irradiation by spot scanning proton beams

NASA Astrophysics Data System (ADS)

Komori, Masataka; Sekihara, Eri; Yabe, Takuya; Horita, Ryo; Toshito, Toshiyuki; Yamamoto, Seiichi

2018-06-01

Luminescence was found during pencil-beam proton irradiation to water phantom and range could be estimated from the luminescence images. However, it is not yet clear whether the luminescence imaging is applied to the uniform fields made of spot-scanning proton-beam irradiations. For this purpose, imaging was conducted for the uniform fields having spread out Bragg peak (SOBP) made by spot scanning proton beams. We designed six types of the uniform fields with different ranges, SOBP widths and irradiation fields. One of the designed fields was irradiated to water phantom and a cooled charge coupled device camera was used to measure the luminescence image during irradiations. We estimated the ranges, field widths, and luminescence intensities from the luminescence images and compared those with the dose distribution calculated by a treatment planning system. For all types of uniform fields, we could obtain clear images of the luminescence showing the SOBPs. The ranges and field widths evaluated from the luminescence were consistent with those of the dose distribution calculated by a treatment planning system within the differences of  ‑4 mm and  ‑11 mm, respectively. Luminescence intensities were almost proportional to the SOBP widths perpendicular to the beam direction. The luminescence imaging could be applied to uniform fields made of spot scanning proton beam irradiations. Ranges and widths of the uniform fields with SOBP could be estimated from the images. The luminescence imaging is promising for the range and field width estimations in proton therapy.

Proton Transfers in a Channelrhodopsin-1 Studied by Fourier Transform Infrared (FTIR) Difference Spectroscopy and Site-directed Mutagenesis*

PubMed Central

Ogren, John I.; Yi, Adrian; Mamaev, Sergey; Li, Hai; Spudich, John L.; Rothschild, Kenneth J.

2015-01-01

Channelrhodopsin-1 from the alga Chlamydomonas augustae (CaChR1) is a low-efficiency light-activated cation channel that exhibits properties useful for optogenetic applications such as a slow light inactivation and a red-shifted visible absorption maximum as compared with the more extensively studied channelrhodopsin-2 from Chlamydomonas reinhardtii (CrChR2). Previously, both resonance Raman and low-temperature FTIR difference spectroscopy revealed that unlike CrChR2, CaChR1 under our conditions exhibits an almost pure all-trans retinal composition in the unphotolyzed ground state and undergoes an all-trans to 13-cis isomerization during the primary phototransition typical of other microbial rhodopsins such as bacteriorhodopsin (BR). Here, we apply static and rapid-scan FTIR difference spectroscopy along with site-directed mutagenesis to characterize the proton transfer events occurring upon the formation of the long-lived conducting P2380 state of CaChR1. Assignment of carboxylic C=O stretch bands indicates that Asp-299 (homolog to Asp-212 in BR) becomes protonated and Asp-169 (homolog to Asp-85 in BR) undergoes a net change in hydrogen bonding relative to the unphotolyzed ground state of CaChR1. These data along with earlier FTIR measurements on the CaChR1 → P1 transition are consistent with a two-step proton relay mechanism that transfers a proton from Glu-169 to Asp-299 during the primary phototransition and from the Schiff base to Glu-169 during P2380 formation. The unusual charge neutrality of both Schiff base counterions in the P2380 conducting state suggests that these residues may function as part of a cation selective filter in the open channel state of CaChR1 as well as other low-efficiency ChRs. PMID:25802337

Proton transfers in a channelrhodopsin-1 studied by Fourier transform infrared (FTIR) difference spectroscopy and site-directed mutagenesis.

PubMed

Ogren, John I; Yi, Adrian; Mamaev, Sergey; Li, Hai; Spudich, John L; Rothschild, Kenneth J

2015-05-15

Channelrhodopsin-1 from the alga Chlamydomonas augustae (CaChR1) is a low-efficiency light-activated cation channel that exhibits properties useful for optogenetic applications such as a slow light inactivation and a red-shifted visible absorption maximum as compared with the more extensively studied channelrhodopsin-2 from Chlamydomonas reinhardtii (CrChR2). Previously, both resonance Raman and low-temperature FTIR difference spectroscopy revealed that unlike CrChR2, CaChR1 under our conditions exhibits an almost pure all-trans retinal composition in the unphotolyzed ground state and undergoes an all-trans to 13-cis isomerization during the primary phototransition typical of other microbial rhodopsins such as bacteriorhodopsin (BR). Here, we apply static and rapid-scan FTIR difference spectroscopy along with site-directed mutagenesis to characterize the proton transfer events occurring upon the formation of the long-lived conducting P2 (380) state of CaChR1. Assignment of carboxylic C=O stretch bands indicates that Asp-299 (homolog to Asp-212 in BR) becomes protonated and Asp-169 (homolog to Asp-85 in BR) undergoes a net change in hydrogen bonding relative to the unphotolyzed ground state of CaChR1. These data along with earlier FTIR measurements on the CaChR1 → P1 transition are consistent with a two-step proton relay mechanism that transfers a proton from Glu-169 to Asp-299 during the primary phototransition and from the Schiff base to Glu-169 during P2 (380) formation. The unusual charge neutrality of both Schiff base counterions in the P2 (380) conducting state suggests that these residues may function as part of a cation selective filter in the open channel state of CaChR1 as well as other low-efficiency ChRs. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Demonstrating the potential of yttrium-doped barium zirconate electrolyte for high-performance fuel cells.

PubMed

Bae, Kiho; Jang, Dong Young; Choi, Hyung Jong; Kim, Donghwan; Hong, Jongsup; Kim, Byung-Kook; Lee, Jong-Ho; Son, Ji-Won; Shim, Joon Hyung

2017-02-23

In reducing the high operating temperatures (≥800 °C) of solid-oxide fuel cells, use of protonic ceramics as an alternative electrolyte material is attractive due to their high conductivity and low activation energy in a low-temperature regime (≤600 °C). Among many protonic ceramics, yttrium-doped barium zirconate has attracted attention due to its excellent chemical stability, which is the main issue in protonic-ceramic fuel cells. However, poor sinterability of yttrium-doped barium zirconate discourages its fabrication as a thin-film electrolyte and integration on porous anode supports, both of which are essential to achieve high performance. Here we fabricate a protonic-ceramic fuel cell using a thin-film-deposited yttrium-doped barium zirconate electrolyte with no impeding grain boundaries owing to the columnar structure tightly integrated with nanogranular cathode and nanoporous anode supports, which to the best of our knowledge exhibits a record high-power output of up to an order of magnitude higher than those of other reported barium zirconate-based fuel cells.

Neutron Structure of Human Carbonic Anhydrase II: Implications for Proton Transfer†

PubMed Central

Fisher, S. Zoë; Kovalevsky, Andrey Y.; Domsic, John F.; Mustyakimov, Marat; McKenna, Robert; Silverman, David N.; Langan, Paul A.

2010-01-01

Human carbonic anhydrase II (HCA II) catalyzes the reversible hydration of carbon dioxide to form bicarbonate and a proton. Despite many high-resolution X-ray crystal structures, mutagenesis, and kinetic data, the structural details of the active site, especially the proton transfer pathway, are unclear. A large HCA II crystal was prepared at pH 9.0 and subjected to vapor H–D exchange to replace labile hydrogens with deuteriums. Neutron diffraction studies were conducted at the Protein Crystallography Station at Los Alamos National Laboratory. The structure to 2.0 Å resolution reveals several interesting active site features: (1) the Zn-bound solvent appearing to be predominantly a D2O molecule, (2) the orientation and hydrogen bonding pattern of solvent molecules in the active site cavity, (3) the side chain of His64 being unprotonated (neutral) and predominantly in an inward conformation pointing toward the zinc, and (4) the phenolic side chain of Tyr7 appearing to be unprotonated. The implications of these details are discussed, and a proposed mechanism for proton transfer is presented. PMID:20025241

Influence of Pectin as a green polymer electrolyte on the transport properties of Chitosan-Pectin membranes.

PubMed

Pasini Cabello, S D; Ochoa, N A; Takara, E A; Mollá, S; Compañ, V

2017-02-10

Novel blend membranes have been prepared from Chitosan (CH), Pectin (PEC) and their mixtures. The obtained samples were cross-linked and sulfonated before characterization. The results show that CH/PEC membranes display structural changes on the chemical and physical properties as a function of composition. DSC analysis reveals an endothermic peak due to the scission of the ionic pairs between carboxylic groups and ammonium groups, which produces a strong change on physical properties such as methanol permeability and proton conductivity. The methanol permeability decreases with the amount of Pectin from (4.24±0.04)×10 -6 cm 2 /s for pure Chitosan membrane to (1.51±0.03)×10 -6 cm 2 /s for blend CH/PEC membranes when the amount of Pectin is 50% (v/v). The proton conductivities of the blend membranes follow a similar behavior. For a pure CH membrane the conductivity is 2.44×10 -3 S/cm, decreasing with pectin content until the composition 50/50 (v/v), in which the conductivity drops almost one order of magnitude. Copyright © 2016 Elsevier Ltd. All rights reserved.

The University of Texas M.D. Anderson Cancer Center Proton Therapy Facility

NASA Astrophysics Data System (ADS)

Smith, Alfred; Newhauser, Wayne; Latinkic, Mitchell; Hay, Amy; McMaken, Bruce; Styles, John; Cox, James

2003-08-01

The University of Texas M.D. Anderson Cancer Center (MDACC), in partnership with Sanders Morris Harris Inc., a Texas-based investment banking firm, and The Styles Company, a developer and manager of hospitals and healthcare facilities, is building a proton therapy facility near the MDACC main complex at the Texas Medical Center in Houston, Texas USA. The MDACC Proton Therapy Center will be a freestanding, investor-owned radiation oncology center offering state-of-the-art proton beam therapy. The facility will have four treatment rooms: three rooms will have rotating, isocentric gantries and the fourth treatment room will have capabilities for both large and small field (e.g. ocular melanoma) treatments using horizontal beam lines. There will be an additional horizontal beam room dedicated to physics research and development, radiation biology research, and outside users who wish to conduct experiments using proton beams. The first two gantries will each be initially equipped with a passive scattering nozzle while the third gantry will have a magnetically swept pencil beam scanning nozzle. The latter will include enhancements to the treatment control system that will allow for the delivery of proton intensity modulation treatments. The proton accelerator will be a 250 MeV zero-gradient synchrotron with a slow extraction system. The facility is expected to open for patient treatments in the autumn of 2005. It is anticipated that 675 patients will be treated during the first full year of operation, while full capacity, reached in the fifth year of operation, will be approximately 3,400 patients per year. Treatments will be given up to 2-shifts per day and 6 days per week.

Chemiosmotic Energy Conservation in Dinoroseobacter shibae: Proton Translocation Driven by Aerobic Respiration, Denitrification, and Photosynthetic Light Reaction.

PubMed

Kirchhoff, Christian; Ebert, Matthias; Jahn, Dieter; Cypionka, Heribert

2018-01-01

Dinoroseobacter shibae is an aerobic anoxygenic phototroph and able to utilize light energy to support its aerobic energy metabolism. Since the cells can also grow anaerobically with nitrate and nitrite as terminal electron acceptor, we were interested in how the cells profit from photosynthesis during denitrification and what the steps of chemiosmotic energy conservation are. Therefore, we conducted proton translocation experiments and compared O 2 - , NO 3 - , and NO 2 - respiration during different light regimes and in the dark. We used wild type cells and transposon mutants with knocked-out nitrate- and nitrite- reductase genes ( napA and nirS ), as well as a mutant ( ppsR ) impaired in bacteriochlorophyll a synthesis. Light had a positive impact on proton translocation, independent of the type of terminal electron acceptor present. In the absence of an electron acceptor, however, light did not stimulate proton translocation. The light-driven add-on to proton translocation was about 1.4 H + /e - for O 2 respiration and about 1.1 H + /e - for NO 3 - and NO 2 - . We could see that the chemiosmotic energy conservation during aerobic respiration involved proton translocation, mediated by the NADH dehydrogenase, the cytochrome bc 1 complex, and the cytochrome c oxidase. During denitrification the last proton translocation step of the electron transport was missing, resulting in a lower H + /e - ratio during anoxia. Furthermore, we studied the type of light-harvesting and found that the cells were able to channel light from the green-blue spectrum most efficiently, while red light has only minor impact. This fits well with the depth profiles for D. shibae abundance in the ocean and the penetration depth of light with different wavelengths into the water column.

Proton irradiation effects on beryllium – A macroscopic assessment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simos, Nikolaos; Elbakhshwan, Mohamed; Zhong, Zhong

Beryllium, due to its excellent neutron multiplication and moderation properties, in conjunction with its good thermal properties, is under consideration for use as plasma facing material in fusion reactors and as a very effective neutron reflector in fission reactors. While it is characterized by unique combination of structural, chemical, atomic number, and neutron absorption cross section it suffers, however, from irradiation generated transmutation gases such as helium and tritium which exhibit low solubility leading to supersaturation of the Be matrix and tend to precipitate into bubbles that coalesce and induce swelling and embrittlement thus degrading the metal and limiting itsmore » lifetime. Utilization of beryllium as a pion production low-Z target in high power proton accelerators has been sought both for its low Z and good thermal properties in an effort to mitigate thermos-mechanical shock that is expected to be induced under the multi-MW power demand. To assess irradiation-induced changes in the thermal and mechanical properties of Beryllium, a study focusing on proton irradiation damage effects has been undertaken using 200 MeV protons from the Brookhaven National Laboratory Linac and followed by a multi-faceted post-irradiation analysis that included the thermal and volumetric stability of irradiated beryllium, the stress-strain behavior and its ductility loss as a function of proton fluence and the effects of proton irradiation on the microstructure using synchrotron X-ray diffraction. The mimicking of high temperature irradiation of Beryllium via high temperature annealing schemes has been conducted as part of the post-irradiation study. This study focuses on the thermal stability and mechanical property changes of the proton irradiated beryllium and presents results of the macroscopic property changes of Beryllium deduced from thermal and mechanical tests.« less

Proton irradiation effects on beryllium – A macroscopic assessment

DOE PAGES

Simos, Nikolaos; Elbakhshwan, Mohamed; Zhong, Zhong; ...

2016-07-01

Beryllium, due to its excellent neutron multiplication and moderation properties, in conjunction with its good thermal properties, is under consideration for use as plasma facing material in fusion reactors and as a very effective neutron reflector in fission reactors. While it is characterized by unique combination of structural, chemical, atomic number, and neutron absorption cross section it suffers, however, from irradiation generated transmutation gases such as helium and tritium which exhibit low solubility leading to supersaturation of the Be matrix and tend to precipitate into bubbles that coalesce and induce swelling and embrittlement thus degrading the metal and limiting itsmore » lifetime. Utilization of beryllium as a pion production low-Z target in high power proton accelerators has been sought both for its low Z and good thermal properties in an effort to mitigate thermos-mechanical shock that is expected to be induced under the multi-MW power demand. To assess irradiation-induced changes in the thermal and mechanical properties of Beryllium, a study focusing on proton irradiation damage effects has been undertaken using 200 MeV protons from the Brookhaven National Laboratory Linac and followed by a multi-faceted post-irradiation analysis that included the thermal and volumetric stability of irradiated beryllium, the stress-strain behavior and its ductility loss as a function of proton fluence and the effects of proton irradiation on the microstructure using synchrotron X-ray diffraction. The mimicking of high temperature irradiation of Beryllium via high temperature annealing schemes has been conducted as part of the post-irradiation study. This study focuses on the thermal stability and mechanical property changes of the proton irradiated beryllium and presents results of the macroscopic property changes of Beryllium deduced from thermal and mechanical tests.« less

Proton irradiation effects on beryllium - A macroscopic assessment

NASA Astrophysics Data System (ADS)

Simos, Nikolaos; Elbakhshwan, Mohamed; Zhong, Zhong; Camino, Fernando

2016-10-01

Beryllium, due to its excellent neutron multiplication and moderation properties, in conjunction with its good thermal properties, is under consideration for use as plasma facing material in fusion reactors and as a very effective neutron reflector in fission reactors. While it is characterized by unique combination of structural, chemical, atomic number, and neutron absorption cross section it suffers, however, from irradiation generated transmutation gases such as helium and tritium which exhibit low solubility leading to supersaturation of the Be matrix and tend to precipitate into bubbles that coalesce and induce swelling and embrittlement thus degrading the metal and limiting its lifetime. Utilization of beryllium as a pion production low-Z target in high power proton accelerators has been sought both for its low Z and good thermal properties in an effort to mitigate thermos-mechanical shock that is expected to be induced under the multi-MW power demand. To assess irradiation-induced changes in the thermal and mechanical properties of Beryllium, a study focusing on proton irradiation damage effects has been undertaken using 200 MeV protons from the Brookhaven National Laboratory Linac and followed by a multi-faceted post-irradiation analysis that included the thermal and volumetric stability of irradiated beryllium, the stress-strain behavior and its ductility loss as a function of proton fluence and the effects of proton irradiation on the microstructure using synchrotron X-ray diffraction. The mimicking of high temperature irradiation of Beryllium via high temperature annealing schemes has been conducted as part of the post-irradiation study. This paper focuses on the thermal stability and mechanical property changes of the proton irradiated beryllium and presents results of the macroscopic property changes of Beryllium deduced from thermal and mechanical tests.

Solid state ionics: a Japan perspective

NASA Astrophysics Data System (ADS)

Yamamoto, Osamu

2017-12-01

The 70-year history of scientific endeavor of solid state ionics research in Japan is reviewed to show the contribution of Japanese scientists to the basic science of solid state ionics and its applications. The term 'solid state ionics' was defined by Takehiko Takahashi of Nagoya University, Japan: it refers to ions in solids, especially solids that exhibit high ionic conductivity at a fairly low temperature below their melting points. During the last few decades of exploration, many ion conducting solids have been discovered in Japan such as the copper-ion conductor Rb4Cu16I7Cl13, proton conductor SrCe1-xYxO3, oxide-ion conductor La0.9Sr0.9Ga0.9Mg0.1O3, and lithium-ion conductor Li10GeP2S12. Rb4Cu16I7Cl13 has a conductivity of 0.33 S cm-1 at 25 °C, which is the highest of all room temperature ion conductive solid electrolytes reported to date, and Li10GeP2S12 has a conductivity of 0.012 S cm-1 at 25 °C, which is the highest among lithium-ion conductors reported to date. Research on high-temperature proton conducting ceramics began in Japan. The history, the discovery of novel ionic conductors and the story behind them are summarized along with basic science and technology.