Membranes for redox flow battery applications.

Science.gov (United States)

Prifti, Helen; Parasuraman, Aishwarya; Winardi, Suminto; Lim, Tuti Mariana; Skyllas-Kazacos, Maria

2012-06-19

The need for large scale energy storage has become a priority to integrate renewable energy sources into the electricity grid. Redox flow batteries are considered the best option to store electricity from medium to large scale applications. However, the current high cost of redox flow batteries impedes the wide spread adoption of this technology. The membrane is a critical component of redox flow batteries as it determines the performance as well as the economic viability of the batteries. The membrane acts as a separator to prevent cross-mixing of the positive and negative electrolytes, while still allowing the transport of ions to complete the circuit during the passage of current. An ideal membrane should have high ionic conductivity, low water intake and excellent chemical and thermal stability as well as good ionic exchange capacity. Developing a low cost, chemically stable membrane for redox flow cell batteries has been a major focus for many groups around the world in recent years. This paper reviews the research work on membranes for redox flow batteries, in particular for the all-vanadium redox flow battery which has received the most attention.

Membranes for Redox Flow Battery Applications

Directory of Open Access Journals (Sweden)

Maria Skyllas-Kazacos

2012-06-01

Full Text Available The need for large scale energy storage has become a priority to integrate renewable energy sources into the electricity grid. Redox flow batteries are considered the best option to store electricity from medium to large scale applications. However, the current high cost of redox flow batteries impedes the wide spread adoption of this technology. The membrane is a critical component of redox flow batteries as it determines the performance as well as the economic viability of the batteries. The membrane acts as a separator to prevent cross-mixing of the positive and negative electrolytes, while still allowing the transport of ions to complete the circuit during the passage of current. An ideal membrane should have high ionic conductivity, low water intake and excellent chemical and thermal stability as well as good ionic exchange capacity. Developing a low cost, chemically stable membrane for redox flow cell batteries has been a major focus for many groups around the world in recent years. This paper reviews the research work on membranes for redox flow batteries, in particular for the all-vanadium redox flow battery which has received the most attention.

MEZZO ECONOMICS ANALITYCAL APPROACH AS THE PROPULSIVE PART OF MANAGERIAL ECONOMICS IN TOURISM

OpenAIRE

Kozuharov, Saso

2011-01-01

Mezzo Economics covers the area between the Micro and Macro Economics and the organizational approach of the economics of the integral economic communities, which are made of microeconomic entities. Mezzo Economics represents an organizational loop between the Macro economic system and Micro Economics. Tourism industry is a typical represent of Mezzo Economics. Mezzo Economics Analytical Approach represents a compositional and methodological approach that make constitution of the basic and de...

Dissecting Redox Biology Using Fluorescent Protein Sensors.

Science.gov (United States)

Schwarzländer, Markus; Dick, Tobias P; Meyer, Andreas J; Morgan, Bruce

2016-05-01

Fluorescent protein sensors have revitalized the field of redox biology by revolutionizing the study of redox processes in living cells and organisms. Within one decade, a set of fundamental new insights has been gained, driven by the rapid technical development of in vivo redox sensing. Redox-sensitive yellow and green fluorescent protein variants (rxYFP and roGFPs) have been the central players. Although widely used as an established standard tool, important questions remain surrounding their meaningful use in vivo. We review the growing range of thiol redox sensor variants and their application in different cells, tissues, and organisms. We highlight five key findings where in vivo sensing has been instrumental in changing our understanding of redox biology, critically assess the interpretation of in vivo redox data, and discuss technical and biological limitations of current redox sensors and sensing approaches. We explore how novel sensor variants may further add to the current momentum toward a novel mechanistic and integrated understanding of redox biology in vivo. Antioxid. Redox Signal. 24, 680-712.

Electronically Induced Redox Barriers for Treatment of Groundwater

National Research Council Canada - National Science Library

Sale, Tom; Gilbert, David

2006-01-01

...) and Colorado State University (CSU). The focus is an innovative electrolytic approach for managing redox-sensitive contaminants in groundwater, referred to as electrically induced redox barrier (e-barriers...

Geochemistry of Natural Redox Fronts

International Nuclear Information System (INIS)

Hofmann, B.A.

1999-05-01

Redox fronts are important geochemical boundaries which need to be considered in safety assessment of deep repositories for radioactive waste. In most cases, selected host-rock formations will be reducing due to the presence of ferrous minerals, sulphides, etc. During construction and operation of the repository, air will be introduced into the formation. After repository closure, oxidising conditions may persist locally until all oxygen is consumed. In the case of high-level waste, radiolysis of water may provide an additional source of oxidants. Oxidising conditions within a repository are thus possible and potentially have a strong influence on the mobility of many elements. The rate of movement of redox fronts, the boundary between oxidising and reducing environments, and their influence on migrating radionuclides are thus important factors influencing repository performance. The present report is a review of elemental behaviour at natural redox fronts, based on published information and work of the author. Redox fronts are geochemically and geometrically variable manifestations of a global interface between generally oxidising geochemical milieux in contact with the atmosphere and generally reducing milieux in contact with rocks containing ferrous iron, sulphide and/or organic carbon. A classification of redox fronts based on a subdivision into continental near-surface, marine near-surface, and deep environments is proposed. The global redox interface is often located close to the surface of rocks and sediments and, sometimes, within bodies of water. Temperature conditions are close to ambient. A deeper penetration of the global redox front to depths of several kilometres is found in basins containing oxidised sediments (red beds) and in some hydrothermal circulation systems. Temperatures at such deep redox fronts may reach 200 o C. Both near-surface and deep redox fronts are sites of formation of economic deposits of redox-sensitive elements, particularly of

A cascade of acid-promoted C-O bond cleavage and redox reactions: from oxa-bridged benzazepines to benzazepinones.

Science.gov (United States)

Zhang, Yuewei; Yang, Fengzhi; Zheng, Lianyou; Dang, Qun; Bai, Xu

2014-12-05

A sequence of C-O bond cleavage and redox reactions in oxa-bridged azepines was realized under acid promoted conditions. This protocol provides an atom-economical and straightforward approach to access benzo[b]azepin-5(2H)-ones in high yields. The formal synthesis of tolvaptan was achieved by exploiting this new transformation.

Redox-assisted Li+-storage in lithium-ion batteries

International Nuclear Information System (INIS)

Huang Qizhao; Wang Qing

2016-01-01

Interfacial charge transfer is the key kinetic process dictating the operation of lithium-ion battery. Redox-mediated charge propagations of the electronic (e − and h + ) and ionic species (Li + ) at the electrode–electrolyte interface have recently gained increasing attention for better exploitation of battery materials. This article briefly summarises the energetic and kinetic aspects of lithium-ion batteries, and reviews the recent progress on various redox-assisted Li + storage approaches. From molecular wiring to polymer wiring and from redox targeting to redox flow lithium battery, the role of redox mediators and the way of the redox species functioning in lithium-ion batteries are discussed. (topical review)

A redox proteomics approach to investigate the mode of action of nanomaterials

Energy Technology Data Exchange (ETDEWEB)

Riebeling, Christian [German Federal Institute for Risk Assessment (BfR), Department of Chemicals and Product Safety, Berlin (Germany); Wiemann, Martin [IBE R& D gGmbH, Institute for Lung Health, Münster (Germany); Schnekenburger, Jürgen [Biomedical Technology Center, Westfälische Wilhelms-University, Münster (Germany); Kuhlbusch, Thomas A.J. [Institute of Energy and Environmental Technology (IUTA) e.V., Air Quality & Sustainable Nanotechnology, Duisburg (Germany); Center for Nanointegration CENIDE, University of Duisburg-Essen, Duisburg, Germany, (Germany); Wohlleben, Wendel [BASF SE, Material Physics, Ludwigshafen (Germany); Luch, Andreas [German Federal Institute for Risk Assessment (BfR), Department of Chemicals and Product Safety, Berlin (Germany); Haase, Andrea, E-mail: andrea.haase@bfr.bund.de [German Federal Institute for Risk Assessment (BfR), Department of Chemicals and Product Safety, Berlin (Germany)

2016-05-15

Numbers of engineered nanomaterials (ENMs) are steadily increasing. Therefore, alternative testing approaches with reduced costs and high predictivity suitable for high throughput screening and prioritization are urgently needed to ensure a fast and effective development of safe products. In parallel, extensive research efforts are targeted to understanding modes of action of ENMs, which may also support the development of new predictive assays. Oxidative stress is a widely accepted paradigm associated with different adverse outcomes of ENMs. It has frequently been identified in in vitro and in vivo studies and different assays have been developed for this purpose. Fluorescent dye based read-outs are most frequently used for cell testing in vitro but may be limited due to possible interference of the ENMs. Recently, other assays have been put forward such as acellular determination of ROS production potential using methods like electron spin resonance, antioxidant quantification or the use of specific sensors. In addition, Omics based approaches have gained increasing attention. In particular, redox proteomics can combine the assessment of oxidative stress with the advantage of getting more detailed mechanistic information. Here we propose a comprehensive testing strategy for assessing the oxidative stress potential of ENMs, which combines acellular methods and fast in vitro screening approaches, as well as a more involved detailed redox proteomics approach. This allows for screening and prioritization in a first tier and, if required, also for unraveling mechanistic details down to compromised signaling pathways. - Highlights: • Oxidative stress is a general paradigm for nanomaterial hazard mechanism of action. • Reactive oxygen species generation can be predicted using acellular assays. • Cellular assays based on fluorescence suffer from interference by nanomaterials. • Protein carbonylation is an irreversible and predictive mark of oxidative stress. �

Quantitative proteomic characterization of redox-dependent post-translational modifications on protein cysteines

Energy Technology Data Exchange (ETDEWEB)

Duan, Jicheng; Gaffrey, Matthew J.; Qian, Wei-Jun

2017-01-01

Protein cysteine thiols play a crucial role in redox signaling, regulation of enzymatic activity and protein function, and maintaining redox homeostasis in living systems. The unique chemical reactivity of thiol groups makes cysteine susceptible to oxidative modifications by reactive oxygen and nitrogen species to form a broad array of reversible and irreversible protein post-translational modifications (PTMs). The reversible modifications in particular are one of the major components of redox signaling and are involved in regulation of various cellular processes under physiological and pathological conditions. The biological significance of these redox PTMs in health and diseases has been increasingly recognized. Herein, we review the recent advances of quantitative proteomic approaches for investigating redox PTMs in complex biological systems, including the general considerations of sample processing, various chemical or affinity enrichment strategies, and quantitative approaches. We also highlight a number of redox proteomic approaches that enable effective profiling of redox PTMs for addressing specific biological questions. Although some technological limitations remain, redox proteomics is paving the way towards a better understanding of redox signaling and regulation in human health and diseases.

Symproportionation versus Disproportionation in Bromine Redox Systems

International Nuclear Information System (INIS)

Toporek, Marcin; Michałowska-Kaczmarczyk, Anna M.; Michałowski, Tadeusz

2015-01-01

Graphical abstract: Display Omitted -- Highlights: • The disproportionation and symproportionation of bromine in different media is presented. • All the redox systems are elaborated according to the principles of the generalized approach to electrolytic redox systems (GATES/GEB). • All physicochemical knowledge is involved in the algorithm applied for this purpose. • The graphical representation of the systems is the basis of gaining the detailed physicochemical knowledge on the systems in question. -- Abstract: The paper refers to dynamic (titration) redox systems where symproportionation or disproportionation of bromine species occur. The related systems are modeled according to principles assumed in the Generalized Approach to Electrolytic Redox Systems (GATES), with Generalized Electron Balance (GEB) concept involved in the GATES/GEB software. The results obtained from calculations made with use of iterative computer programs prepared according to MATLAB computational software, are presented graphically, as 2D and 3D graphs

Investigating improvements on redox flow batteries

CSIR Research Space (South Africa)

Swartbooi, AM

2006-09-01

Full Text Available storage devices coupled to most of their applications. Lead-acid batteries have long been used as the most economical option to store electricity in many small scale applications, but lately more interest have been shown in redox flow batteries. The low...

Redox Species of Redox Flow Batteries: A Review.

Science.gov (United States)

Pan, Feng; Wang, Qing

2015-11-18

Due to the capricious nature of renewable energy resources, such as wind and solar, large-scale energy storage devices are increasingly required to make the best use of the renewable power. The redox flow battery is considered suitable for large-scale applications due to its modular design, good scalability and flexible operation. The biggest challenge of the redox flow battery is the low energy density. The redox active species is the most important component in redox flow batteries, and the redox potential and solubility of redox species dictate the system energy density. This review is focused on the recent development of redox species. Different categories of redox species, including simple inorganic ions, metal complexes, metal-free organic compounds, polysulfide/sulfur and lithium storage active materials, are reviewed. The future development of redox species towards higher energy density is also suggested.

Redox Species of Redox Flow Batteries: A Review

Directory of Open Access Journals (Sweden)

Feng Pan

2015-11-01

Full Text Available Due to the capricious nature of renewable energy resources, such as wind and solar, large-scale energy storage devices are increasingly required to make the best use of the renewable power. The redox flow battery is considered suitable for large-scale applications due to its modular design, good scalability and flexible operation. The biggest challenge of the redox flow battery is the low energy density. The redox active species is the most important component in redox flow batteries, and the redox potential and solubility of redox species dictate the system energy density. This review is focused on the recent development of redox species. Different categories of redox species, including simple inorganic ions, metal complexes, metal-free organic compounds, polysulfide/sulfur and lithium storage active materials, are reviewed. The future development of redox species towards higher energy density is also suggested.

Redox-Flow Batteries: From Metals to Organic Redox-Active Materials.

Science.gov (United States)

Winsberg, Jan; Hagemann, Tino; Janoschka, Tobias; Hager, Martin D; Schubert, Ulrich S

2017-01-16

Research on redox-flow batteries (RFBs) is currently experiencing a significant upturn, stimulated by the growing need to store increasing quantities of sustainably generated electrical energy. RFBs are promising candidates for the creation of smart grids, particularly when combined with photovoltaics and wind farms. To achieve the goal of "green", safe, and cost-efficient energy storage, research has shifted from metal-based materials to organic active materials in recent years. This Review presents an overview of various flow-battery systems. Relevant studies concerning their history are discussed as well as their development over the last few years from the classical inorganic, to organic/inorganic, to RFBs with organic redox-active cathode and anode materials. Available technologies are analyzed in terms of their technical, economic, and environmental aspects; the advantages and limitations of these systems are also discussed. Further technological challenges and prospective research possibilities are highlighted. © 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Study to establish cost projections for production of Redox chemicals

Science.gov (United States)

Walther, J. F.; Greco, C. C.; Rusinko, R. N.; Wadsworth, A. L., III

1982-01-01

A cost study of four proposed manufacturing processes for redox chemicals for the NASA REDOX Energy Storage System yielded favorable selling prices in the range $0.99 to $1.91/kg of chromic chloride, anhydrous basis, including ferrous chloride. The prices corresponded to specific energy storage costs from under $9 to $17/kWh. A refined and expanded cost analysis of the most favored process yielded a price estimate corresponding to a storage cost of $11/kWh. The findings supported the potential economic viability of the NASA REDOX system.

Characterization of redox conditions in pollution plumes

DEFF Research Database (Denmark)

Christensen, Thomas Højlund; Bjerg, Poul Løgstrup; Banwart, Steven A.

2000-01-01

Evalution of redox conditions in groundwater pollution plumes is often a prerequisite for understanding the behviour of the pollutants in the plume and for selecting remediation approaches. Measuring of redox conditions in pollution plumes is, however, a fairly recent issue and yet relative few...

Analytical redox reactions and redox potentials of tungsten and its concomitants

Energy Technology Data Exchange (ETDEWEB)

Wuensch, G.; Mintrop, L.; Tracht, U.

1985-01-01

It is demonstrated that tungsten can be more effectively determined by redox titrimetry than by gravimetry. In addition to its inherent greater simplicity the volumetric approach offers to determine several components of the sample from consecutive redox titrations. To provide the necessary information the conditional redox potentials of W, Mo, Fe, V, Ti, Sn, Cu, Cr in HCl, HCl + HF and HCl + H/sub 3/PO/sub 4/ have been determined. Use of HF and/or H/sub 3/PO/sub 4/ allows sample preparations without any precipitation of tungstic acid. The influence of these auxiliary complexing agents on the potentials and kinetics is discussed. The titrations can be performed reductimetrically or more conveniently oxidimetrically using potentiometric or amperometric indication. The use of strongly reducing agents restricts the tolerance interval to +-0.6%, so that the gravimetric determination of tungsten remains superior for high precision analyses.

Analytical redox reactions and redox potentials of tungsten and its concomitants

International Nuclear Information System (INIS)

Wuensch, G.; Mintrop, L.; Tracht, U.

1985-01-01

It is demonstrated that tungsten can be more effectively determined by redox titrimetry than by gravimetry. In addition to its inherent greater simplicity the volumetric approach offers to determine several components of the sample from consecutive redox titrations. To provide the necessary information the conditional redox potentials of W, Mo, Fe, V, Ti, Sn, Cu, Cr in HCl, HCl + HF and HCl + H 3 PO 4 have been determined. Use of HF and/or H 3 PO 4 allows sample preparations without any precipitation of tungstic acid. The influence of these auxiliary complexing agents on the potentials and kinetics is discussed. The titrations can be performed reductimetrically or more conveniently oxidimetrically using potentiometric or amperometric indication. The use of strongly reducing agents restricts the tolerance interval to +-0.6%, so that the gravimetric determination of tungsten remains superior for high precision analyses. (orig.) [de

Thermochemical storage for CSP via redox structured reactors/heat exchangers: The RESTRUCTURE project

Science.gov (United States)

Karagiannakis, George; Pagkoura, Chrysoula; Konstandopoulos, Athanasios G.; Tescari, Stefania; Singh, Abhishek; Roeb, Martin; Lange, Matthias; Marcher, Johnny; Jové, Aleix; Prieto, Cristina; Rattenbury, Michael; Chasiotis, Andreas

2017-06-01

The present work provides an overview of activities performed in the framework of the EU-funded collaborative project RESTRUCTURE, the main goal of which was to develop and validate a compact structured reactor/heat exchanger for thermochemical storage driven by 2-step high temperature redox metal oxide cycles. The starting point of development path included redox materials qualification via both theoretical and lab-scale experimental studies. Most favorable compositions were cobalt oxide/alumina composites. Preparation of small-scale structured bodies included various approaches, ranging from perforated pellets to more sophisticated honeycomb geometries, fabricated by extrusion and coating. Proof-of-concept of the proposed novel reactor/heat exchanger was successfully validated in small-scale structures and the next step included scaling up of redox honeycombs production. Significant challenges were identified for the case of extruded full-size bodies and the final qualified approach related to preparation of cordierite substrates coated with cobalt oxide. The successful experimental evaluation of the pilot reactor/heat exchanger system constructed motivated the preliminary techno-economic evaluation of the proposed novel thermochemical energy storage concept. Taking into account experimental results, available technologies and standard design aspects a model for a 70.5 MWe CSP plant was defined. Estimated LCOE costs were calculated to be in the range of reference values for Combined Cycle Power Plants operated by natural gas. One of main cost contributors was the storage system itself, partially due to relatively high cost of cobalt oxide. This highlighted the need to identify less costly and equally efficient to cobalt oxide redox materials.

Redox-capacitor to connect electrochemistry to redox-biology.

Science.gov (United States)

Kim, Eunkyoung; Leverage, W Taylor; Liu, Yi; White, Ian M; Bentley, William E; Payne, Gregory F

2014-01-07

It is well-established that redox-reactions are integral to biology for energy harvesting (oxidative phosphorylation), immune defense (oxidative burst) and drug metabolism (phase I reactions), yet there is emerging evidence that redox may play broader roles in biology (e.g., redox signaling). A critical challenge is the need for tools that can probe biologically-relevant redox interactions simply, rapidly and without the need for a comprehensive suite of analytical methods. We propose that electrochemistry may provide such a tool. In this tutorial review, we describe recent studies with a redox-capacitor film that can serve as a bio-electrode interface that can accept, store and donate electrons from mediators commonly used in electrochemistry and also in biology. Specifically, we (i) describe the fabrication of this redox-capacitor from catechols and the polysaccharide chitosan, (ii) discuss the mechanistic basis for electron exchange, (iii) illustrate the properties of this redox-capacitor and its capabilities for promoting redox-communication between biology and electrodes, and (iv) suggest the potential for enlisting signal processing strategies to "extract" redox information. We believe these initial studies indicate broad possibilities for enlisting electrochemistry and signal processing to acquire "systems level" redox information from biology.

Ecological Economics: Themes, Approaches, and Differences with Environmental Economics

OpenAIRE

Jeroen C.J.M. van den Bergh

2000-01-01

This provides a short overview of the main themes of ecological economics (EE). It isargued that EE provides a platform that fosters multidisciplinary environmental research bybringing together the core contributing disciplines economics and ecology. In addition, EE isregarded as a pluralistic approach to environmental research that can be set opposite to, and hasindeed developed as a response to, traditional environmental and resource economics. Acomparison of the two fields is presented to ...

New lab scale approaches for quantification of redox conditions

Science.gov (United States)

Fernandez, P. M.; Dathe, A.; Nadeem, S.; Bakken, L. R.; Bloem, E.; French, H. K.; Binley, A. M.

2013-12-01

Degradation of organic chemicals in the unsaturated zone is a process highly relevant for developing remediation techniques for protecting groundwater. Degradation causes changes in chemical composition of the water phase and gas releases. These changes can potentially be mapped with electrical resistivity measurements in the bulk soil and gas measurements at the soil surface. The redox potential combined with the local geological conditions determines the composition of available electron acceptors as well as microbial degradation pathways and how the soil system is affected in the long term. After oxygen and nitrate are depleted, manganese and iron should be reduced. However, in experiments conducted in the unsaturated zone at Gardermoen airport, Norway, it was found that for the degradation of the de-icing agent propylene glycol (PG), manganese and iron were preferred over nitrate as electron acceptor. A key hypothesis for the work presented is that for a designated soil, the redox potential affects gas releases and soil solution composition profoundly. As the redox potential decreases, the reactants of the degradation change and therefore the composition of the soil-water system changes. These changes can be quantified dynamically by gas measurements and changes in electrical conductivity of the pore water and electrical resistivity of the bulk soil. Batch experiments were conducted to examine whether nitrate is a preferred electron acceptor over iron and manganese oxides as described in classical redox reaction theory. Gas releases during PG and glutamate degradation were measured in a sandy pristine soil with and without nitrate under anaerobic condition during two weeks of incubation. Chemical reactions were quantified with the modelling tool ORCHESTRA. We are currently investigating whether dynamical measurements of electrical conductivity and bulk resistivity are suited to trace which electron acceptors (nitrate, manganese or iron) are being reduced. First

Engineering redox homeostasis to develop efficient alcohol-producing microbial cell factories.

Science.gov (United States)

Zhao, Chunhua; Zhao, Qiuwei; Li, Yin; Zhang, Yanping

2017-06-24

The biosynthetic pathways of most alcohols are linked to intracellular redox homeostasis, which is crucial for life. This crucial balance is primarily controlled by the generation of reducing equivalents, as well as the (reduction)-oxidation metabolic cycle and the thiol redox homeostasis system. As a main oxidation pathway of reducing equivalents, the biosynthesis of most alcohols includes redox reactions, which are dependent on cofactors such as NADH or NADPH. Thus, when engineering alcohol-producing strains, the availability of cofactors and redox homeostasis must be considered. In this review, recent advances on the engineering of cellular redox homeostasis systems to accelerate alcohol biosynthesis are summarized. Recent approaches include improving cofactor availability, manipulating the affinity of redox enzymes to specific cofactors, as well as globally controlling redox reactions, indicating the power of these approaches, and opening a path towards improving the production of a number of different industrially-relevant alcohols in the near future.

Solar fuel processing efficiency for ceria redox cycling using alternative oxygen partial pressure reduction methods

International Nuclear Information System (INIS)

Lin, Meng; Haussener, Sophia

2015-01-01

Solar-driven non-stoichiometric thermochemical redox cycling of ceria for the conversion of solar energy into fuels shows promise in achieving high solar-to-fuel efficiency. This efficiency is significantly affected by the operating conditions, e.g. redox temperatures, reduction and oxidation pressures, solar irradiation concentration, or heat recovery effectiveness. We present a thermodynamic analysis of five redox cycle designs to investigate the effects of working conditions on the fuel production. We focused on the influence of approaches to reduce the partial pressure of oxygen in the reduction step, namely by mechanical approaches (sweep gassing or vacuum pumping), chemical approaches (chemical scavenger), and combinations thereof. The results indicated that the sweep gas schemes work more efficient at non-isothermal than isothermal conditions, and efficient gas phase heat recovery and sweep gas recycling was important to ensure efficient fuel processing. The vacuum pump scheme achieved best efficiencies at isothermal conditions, and at non-isothermal conditions heat recovery was less essential. The use of oxygen scavengers combined with sweep gas and vacuum pump schemes further increased the system efficiency. The present work can be used to predict the performance of solar-driven non-stoichiometric redox cycles and further offers quantifiable guidelines for system design and operation. - Highlights: • A thermodynamic analysis was conducted for ceria-based thermochemical cycles. • Five novel cycle designs and various operating conditions were proposed and investigated. • Pressure reduction method affects optimal operating conditions for maximized efficiency. • Chemical oxygen scavenger proves to be promising in further increasing efficiency. • Formulation of quantifiable design guidelines for economical competitive solar fuel processing

Facile approach to prepare pH and redox-responsive nanogels via Diels-Alder click reaction

Directory of Open Access Journals (Sweden)

C. M. Q. Le

2018-08-01

Full Text Available A novel pH and redox responsive system of sub-100 nm nanogels was prepared by arm-first approach via Diels-Alder click reaction. First, well-defined poly(ethylene glycol-block-poly(styrene-alt-maleic anhydride (PEG-b-PSM was synthesized and subsequently functionalized with furfuryl amine, leading to the formation of the dual-functional block copolymer of PEG-b-PSMf. The furfuryl groups in the PSMf block were employed to incorporate a redox-responsive linkage and the carboxylic acid moieties generated through functionalization acted as a pH-responsive part. The Diels-Alder click reaction between a bismaleimide crosslinker and PEG-b-PSMf was conducted at 60 °C, affording star-like nanogel structures. Doxorubicin, a model anticancer drug, was loaded into to the core of the nanogels primarily by the ionic interaction with carboxylates of core blocks and a highest drug loading capacity of 38.1% was obtained. Furthermore, the in vitro profile showed a low release percentage (11.2% of DOX at PBS pH 7.4, whereas a burst release (62% at pH 5.0 in the presence of 10 mM glutathione, indicating the effective pH and redox responsive characteristic of the PEG-b-PSMf nanogels.

Generalized kinetic model of reduction of molecular oxidant by metal containing redox

International Nuclear Information System (INIS)

Kravchenko, T.A.

1986-01-01

Present work is devoted to kinetics of reduction of molecular oxidant by metal containing redox. Constructed generalized kinetic model of redox process in the system solid redox - reagent solution allows to perform the general theoretical approach to research and to obtain new results on kinetics and mechanism of interaction of redox with oxidants.

The Redox Code.

Science.gov (United States)

Jones, Dean P; Sies, Helmut

2015-09-20

The redox code is a set of principles that defines the positioning of the nicotinamide adenine dinucleotide (NAD, NADP) and thiol/disulfide and other redox systems as well as the thiol redox proteome in space and time in biological systems. The code is richly elaborated in an oxygen-dependent life, where activation/deactivation cycles involving O₂ and H₂O₂ contribute to spatiotemporal organization for differentiation, development, and adaptation to the environment. Disruption of this organizational structure during oxidative stress represents a fundamental mechanism in system failure and disease. Methodology in assessing components of the redox code under physiological conditions has progressed, permitting insight into spatiotemporal organization and allowing for identification of redox partners in redox proteomics and redox metabolomics. Complexity of redox networks and redox regulation is being revealed step by step, yet much still needs to be learned. Detailed knowledge of the molecular patterns generated from the principles of the redox code under defined physiological or pathological conditions in cells and organs will contribute to understanding the redox component in health and disease. Ultimately, there will be a scientific basis to a modern redox medicine.

Are bioassays useful tools to assess redox processes and biodegradation?

DEFF Research Database (Denmark)

Albrechtsen, Hans-Jørgen; Pedersen, Philip Grinder; Ludvigsen, L.

2002-01-01

sensitive hydrochemical or geochemical parameters, levels of hydrogen, and redox potential. However, all these approaches have to be evaluated against TEAP-bioassays as the most direct measure. We assessed successfully ongoing microbial-mediated redox processes by TEAP-bioassays in degradation studies...... of aromatic and chlorinated aliphatic compounds in landfill leachate plumes, and of pesticides in aquifers with various redox conditions....

Redox fronts

International Nuclear Information System (INIS)

Chapman, N.; McKinley, I.; Shea, M.; Smellie, J.

1993-01-01

This article describes the investigations of redox fronts performed at the Osamu Utsumi mine. Results obtained by modelling groups on the rate of movement of the redox fronts and on the chemical reactions involved are discussed. Some of the most important rockwater interactions which occur at redox fronts can be modelled reasonably well but the complex redox chemistry of elements like sulphur is poorly simulated. The observed enrichment of many trace elements close to the redox fronts could be of significance for high-level waste repositories, but cannot be quantified by existing models. (author) 6 figs., 1 tab

Engineered Proteins: Redox Properties and Their Applications

Science.gov (United States)

Prabhulkar, Shradha; Tian, Hui; Wang, Xiaotang; Zhu, Jun-Jie

2012-01-01

Abstract Oxidoreductases and metalloproteins, representing more than one third of all known proteins, serve as significant catalysts for numerous biological processes that involve electron transfers such as photosynthesis, respiration, metabolism, and molecular signaling. The functional properties of the oxidoreductases/metalloproteins are determined by the nature of their redox centers. Protein engineering is a powerful approach that is used to incorporate biological and abiological redox cofactors as well as novel enzymes and redox proteins with predictable structures and desirable functions for important biological and chemical applications. The methods of protein engineering, mainly rational design, directed evolution, protein surface modifications, and domain shuffling, have allowed the creation and study of a number of redox proteins. This review presents a selection of engineered redox proteins achieved through these methods, resulting in a manipulation in redox potentials, an increase in electron-transfer efficiency, and an expansion of native proteins by de novo design. Such engineered/modified redox proteins with desired properties have led to a broad spectrum of practical applications, ranging from biosensors, biofuel cells, to pharmaceuticals and hybrid catalysis. Glucose biosensors are one of the most successful products in enzyme electrochemistry, with reconstituted glucose oxidase achieving effective electrical communication with the sensor electrode; direct electron-transfer-type biofuel cells are developed to avoid thermodynamic loss and mediator leakage; and fusion proteins of P450s and redox partners make the biocatalytic generation of drug metabolites possible. In summary, this review includes the properties and applications of the engineered redox proteins as well as their significance and great potential in the exploration of bioelectrochemical sensing devices. Antioxid. Redox Signal. 17, 1796–1822. PMID:22435347

Information processing through a bio-based redox capacitor: signatures for redox-cycling.

Science.gov (United States)

Liu, Yi; Kim, Eunkyoung; White, Ian M; Bentley, William E; Payne, Gregory F

2014-08-01

Redox-cycling compounds can significantly impact biological systems and can be responsible for activities that range from pathogen virulence and contaminant toxicities, to therapeutic drug mechanisms. Current methods to identify redox-cycling activities rely on the generation of reactive oxygen species (ROS), and employ enzymatic or chemical methods to detect ROS. Here, we couple the speed and sensitivity of electrochemistry with the molecular-electronic properties of a bio-based redox-capacitor to generate signatures of redox-cycling. The redox capacitor film is electrochemically-fabricated at the electrode surface and is composed of a polysaccharide hydrogel with grafted catechol moieties. This capacitor film is redox-active but non-conducting and can engage diffusible compounds in either oxidative or reductive redox-cycling. Using standard electrochemical mediators ferrocene dimethanol (Fc) and Ru(NH3)6Cl3 (Ru(3+)) as model redox-cyclers, we observed signal amplifications and rectifications that serve as signatures of redox-cycling. Three bio-relevant compounds were then probed for these signatures: (i) ascorbate, a redox-active compound that does not redox-cycle; (ii) pyocyanin, a virulence factor well-known for its reductive redox-cycling; and (iii) acetaminophen, an analgesic that oxidatively redox-cycles but also undergoes conjugation reactions. These studies demonstrate that the redox-capacitor can enlist the capabilities of electrochemistry to generate rapid and sensitive signatures of biologically-relevant chemical activities (i.e., redox-cycling). Published by Elsevier B.V.

Redox behaviors of iron by absorption spectroscopy and redox potential measurement

International Nuclear Information System (INIS)

Oh, Jae Yong

2010-02-01

This work is performed to study the redox (reduction/oxidation) behaviors of iron in aqueous system by a combination of absorption spectroscopy and redox potential measurements. There are many doubts on redox potential measurements generally showing low accuracies and high uncertainties. In the present study, redox potentials are measured by utilizing various redox electrodes such as Pt, Au, Ag, and glassy carbon (GC) electrodes. Measured redox potentials are compared with calculated redox potentials based on the chemical oxidation speciation of iron and thermodynamic data by absorption spectroscopy, which provides one of the sensitive and selective spectroscopic methods for the chemical speciation of Fe(II/III). From the comparison analyses, redox potential values measured by the Ag redox electrode are fairly consistent with those calculated by the chemical aqueous speciation of iron in the whole system. In summary, the uncertainties of measured redox potentials are closely related with the total Fe concentration and affected by the formation of mixed potentials due to Fe(III) precipitates in the pH range of 6 ∼ 9 beyond the solubility of Fe(III), whilst being independent of the initially prepared concentration ratios between Fe(II) and Fe(III)

Social surplus approach and heterodox economics

OpenAIRE

Lee, Frederic; Jo, Tae-Hee

2010-01-01

Given the emphasis on social provisioning in heterodox economics, two of its central theoretical organizing principles are the concepts of the total social product and the social surplus. This appears to link heterodox economics to the social surplus approach associated with the classical economists and currently with Sraffian economists. However, heterodox economics connects agency with the social surplus and the social product, which the Sraffians reject as they take the level and composit...

Economic Gardening through Entrepreneurship Education: A Service-Learning Approach

Science.gov (United States)

Desplaces, David E.; Wergeles, Fred; McGuigan, Patrick

2009-01-01

This article outlines the implementation of a service-learning approach in an entrepreneurship programme using an "economic gardening" strategy. Economic Gardening through Service-Learning (EGS-L) is an approach to economic development that helps local businesses and students grow through a facilitated learning process. Learning is made possible…

Plant redox proteomics

DEFF Research Database (Denmark)

Navrot, Nicolas; Finnie, Christine; Svensson, Birte

2011-01-01

PTMs in regulating enzymatic activities and controlling biological processes in plants. Notably, proteins controlling the cellular redox state, e.g. thioredoxin and glutaredoxin, appear to play dual roles to maintain oxidative stress resistance and regulate signal transduction pathways via redox PTMs......In common with other aerobic organisms, plants are exposed to reactive oxygen species resulting in formation of post-translational modifications related to protein oxidoreduction (redox PTMs) that may inflict oxidative protein damage. Accumulating evidence also underscores the importance of redox....... To get a comprehensive overview of these types of redox-regulated pathways there is therefore an emerging interest to monitor changes in redox PTMs on a proteome scale. Compared to some other PTMs, e.g. protein phosphorylation, redox PTMs have received less attention in plant proteome analysis, possibly...

Spatial Economics: The Evolution of Approaches and Methodology

Directory of Open Access Journals (Sweden)

Minakir P. A.

2010-06-01

Full Text Available The evolution of theoretical principles and approaches to the study of spatial organization of the economy is set forth. The changes in the content of the category «economic region» are analyzed. A comparative assessment is given of theoretical approaches to studying spatial aspects of the economy. The limited character of theoretical and applied regional economic tools in studying spatial organization and spatial interactions between economic agents of the modern economy is shown

Assessing sufficient capability: A new approach to economic evaluation.

Science.gov (United States)

Mitchell, Paul Mark; Roberts, Tracy E; Barton, Pelham M; Coast, Joanna

2015-08-01

Amartya Sen's capability approach has been discussed widely in the health economics discipline. Although measures have been developed to assess capability in economic evaluation, there has been much less attention paid to the decision rules that might be applied alongside. Here, new methods, drawing on the multidimensional poverty and health economics literature, are developed for conducting economic evaluation within the capability approach and focusing on an objective of achieving "sufficient capability". This objective more closely reflects the concern with equity that pervades the capability approach and the method has the advantage of retaining the longitudinal aspect of estimating outcome that is associated with quality-adjusted life years (QALYs), whilst also drawing on notions of shortfall associated with assessments of poverty. Economic evaluation from this perspective is illustrated in an osteoarthritis patient group undergoing joint replacement, with capability wellbeing assessed using ICECAP-O. Recommendations for taking the sufficient capability approach forward are provided. Copyright © 2015 Elsevier Ltd. All rights reserved.

Organic Redox Species in Aqueous Flow Batteries: Redox Potentials, Chemical Stability and Solubility

Science.gov (United States)

Wedege, Kristina; Dražević, Emil; Konya, Denes; Bentien, Anders

2016-01-01

Organic molecules are currently investigated as redox species for aqueous low-cost redox flow batteries (RFBs). The envisioned features of using organic redox species are low cost and increased flexibility with respect to tailoring redox potential and solubility from molecular engineering of side groups on the organic redox-active species. In this paper 33, mainly quinone-based, compounds are studied experimentially in terms of pH dependent redox potential, solubility and stability, combined with single cell battery RFB tests on selected redox pairs. Data shows that both the solubility and redox potential are determined by the position of the side groups and only to a small extent by the number of side groups. Additionally, the chemical stability and possible degradation mechanisms leading to capacity loss over time are discussed. The main challenge for the development of all-organic RFBs is to identify a redox pair for the positive side with sufficiently high stability and redox potential that enables battery cell potentials above 1 V. PMID:27966605

Organic Redox Species in Aqueous Flow Batteries: Redox Potentials, Chemical Stability and Solubility

Science.gov (United States)

Wedege, Kristina; Dražević, Emil; Konya, Denes; Bentien, Anders

2016-12-01

Organic molecules are currently investigated as redox species for aqueous low-cost redox flow batteries (RFBs). The envisioned features of using organic redox species are low cost and increased flexibility with respect to tailoring redox potential and solubility from molecular engineering of side groups on the organic redox-active species. In this paper 33, mainly quinone-based, compounds are studied experimentially in terms of pH dependent redox potential, solubility and stability, combined with single cell battery RFB tests on selected redox pairs. Data shows that both the solubility and redox potential are determined by the position of the side groups and only to a small extent by the number of side groups. Additionally, the chemical stability and possible degradation mechanisms leading to capacity loss over time are discussed. The main challenge for the development of all-organic RFBs is to identify a redox pair for the positive side with sufficiently high stability and redox potential that enables battery cell potentials above 1 V.

Organic Redox Species in Aqueous Flow Batteries: Redox Potentials, Chemical Stability and Solubility

OpenAIRE

Kristina Wedege; Emil Dražević; Denes Konya; Anders Bentien

2016-01-01

Organic molecules are currently investigated as redox species for aqueous low-cost redox flow batteries (RFBs). The envisioned features of using organic redox species are low cost and increased flexibility with respect to tailoring redox potential and solubility from molecular engineering of side groups on the organic redox-active species. In this paper 33, mainly quinone-based, compounds are studied experimentially in terms of pH dependent redox potential, solubility and stability, combined ...

Teaching Business and Economic Journalism: Fresh Approaches

Science.gov (United States)

Weber, Joseph

2016-01-01

Teachers of business and economic journalism are developing creative approaches to attracting students and educating them in a field many find daunting. To recruit, some avoid using the terms "business" or "economic" in course titles, preferring "financial basics" and "financial literacy." Many use novel…

Computational Redox Potential Predictions: Applications to Inorganic and Organic Aqueous Complexes, and Complexes Adsorbed to Mineral Surfaces

Directory of Open Access Journals (Sweden)

Krishnamoorthy Arumugam

2014-04-01

Full Text Available Applications of redox processes range over a number of scientific fields. This review article summarizes the theory behind the calculation of redox potentials in solution for species such as organic compounds, inorganic complexes, actinides, battery materials, and mineral surface-bound-species. Different computational approaches to predict and determine redox potentials of electron transitions are discussed along with their respective pros and cons for the prediction of redox potentials. Subsequently, recommendations are made for certain necessary computational settings required for accurate calculation of redox potentials. This article reviews the importance of computational parameters, such as basis sets, density functional theory (DFT functionals, and relativistic approaches and the role that physicochemical processes play on the shift of redox potentials, such as hydration or spin orbit coupling, and will aid in finding suitable combinations of approaches for different chemical and geochemical applications. Identifying cost-effective and credible computational approaches is essential to benchmark redox potential calculations against experiments. Once a good theoretical approach is found to model the chemistry and thermodynamics of the redox and electron transfer process, this knowledge can be incorporated into models of more complex reaction mechanisms that include diffusion in the solute, surface diffusion, and dehydration, to name a few. This knowledge is important to fully understand the nature of redox processes be it a geochemical process that dictates natural redox reactions or one that is being used for the optimization of a chemical process in industry. In addition, it will help identify materials that will be useful to design catalytic redox agents, to come up with materials to be used for batteries and photovoltaic processes, and to identify new and improved remediation strategies in environmental engineering, for example the

Redox Flow Batteries, Hydrogen and Distributed Storage.

Science.gov (United States)

Dennison, C R; Vrubel, Heron; Amstutz, Véronique; Peljo, Pekka; Toghill, Kathryn E; Girault, Hubert H

2015-01-01

Social, economic, and political pressures are causing a shift in the global energy mix, with a preference toward renewable energy sources. In order to realize widespread implementation of these resources, large-scale storage of renewable energy is needed. Among the proposed energy storage technologies, redox flow batteries offer many unique advantages. The primary limitation of these systems, however, is their limited energy density which necessitates very large installations. In order to enhance the energy storage capacity of these systems, we have developed a unique dual-circuit architecture which enables two levels of energy storage; first in the conventional electrolyte, and then through the formation of hydrogen. Moreover, we have begun a pilot-scale demonstration project to investigate the scalability and technical readiness of this approach. This combination of conventional energy storage and hydrogen production is well aligned with the current trajectory of modern energy and mobility infrastructure. The combination of these two means of energy storage enables the possibility of an energy economy dominated by renewable resources.

Materials and Systems for Organic Redox Flow Batteries: Status and Challenges

Energy Technology Data Exchange (ETDEWEB)

Wei, Xiaoliang [Joint Center for Energy Storage Research (JCESR), Argonne, Illinois 60439, United States; Energy & amp, Environment Directorate, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99354, United States; Pan, Wenxiao [Department; Duan, Wentao [Joint Center for Energy Storage Research (JCESR), Argonne, Illinois 60439, United States; Energy & amp, Environment Directorate, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99354, United States; Hollas, Aaron [Energy & amp, Environment Directorate, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99354, United States; Yang, Zheng [Joint Center for Energy Storage Research (JCESR), Argonne, Illinois 60439, United States; Energy & amp, Environment Directorate, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99354, United States; Li, Bin [Energy & amp, Environment Directorate, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99354, United States; Nie, Zimin [Energy & amp, Environment Directorate, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99354, United States; Liu, Jun [Joint Center for Energy Storage Research (JCESR), Argonne, Illinois 60439, United States; Energy & amp, Environment Directorate, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99354, United States; Reed, David [Energy & amp, Environment Directorate, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99354, United States; Wang, Wei [Energy & amp, Environment Directorate, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99354, United States; Sprenkle, Vincent [Energy & amp, Environment Directorate, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99354, United States

2017-08-14

Redox flow batteries are propitious stationary energy storage technologies with exceptional scalability and flexibility to improve the stability, efficiency and sustainability of our power grid. The redox-active materials are the central component to RFBs for achieving high energy density and good cyclability. Traditional inorganic-based materials encounter critical technical and economic limitations such as low solubility, inferior electrochemical activity, and high cost. Redox-active organic materials (ROMs) are promising alternative “green” candidates to push the boundaries of energy storage because of the significant advantages of molecular diversity, structural tailorability, and natural abundance. Here the recent development of a variety of ROM families and associated battery designs in both aqueous and nonaqueous electrolytes are reviewed. Moreover, the critical challenges and potential research opportunities for developing practically relevant organic flow batteries are discussed.

Characterization of redox conditions in groundwater contaminant plumes

DEFF Research Database (Denmark)

Christensen, Thomas Højlund; Bjerg, Poul Løgstrup; Banwarth, Steven A.

2000-01-01

tools, such as MPN counts, PLFA biomarkers and redox bioassays. This paper reviews the principles behind the different approaches, summarizes methods used and evaluates the approaches based on the experience from the reported applications. C 2000 Elsevier Science B.V. All rights reserved....

BEHAVIORAL INPUTS TO THE THEORETICAL APPROACH OF THE ECONOMIC CRISIS

Directory of Open Access Journals (Sweden)

Sinziana BALTATESCU

2015-09-01

Full Text Available The current economic and financial crisis gave room for the theoretical debates to reemerge. The economic reality challenged the mainstream neoclassical approach leaving the opportunity for the Austrian School, Post Keynesianism or Institutionalists to bring in front theories that seem to better explain the economic crisis and thus, leaving space for more efficient economic policies to result. In this context, the main assumptions of the mainstream theoretical approach are challenged and reevaluated, behavioral economics is one of the main challengers. Without developing in an integrated school of thought yet, behavioral economics brings new elements within the framework of economic thinking. How are the main theoretical approaches integrating these new elements and whether this process is going to narrow the theory or enrich it to be more comprehensive are questions to which this paper tries to answer, or, at least, to leave room for an answer.

Short overview on metabolomic approach and redox changes in psychiatric disorders

Directory of Open Access Journals (Sweden)

Gordana Nedic Erjavec

2018-04-01

Full Text Available Schizophrenia, depression and posttraumatic stress disorder (PTSD are severe mental disorders and complicated diagnostic entities, due to their phenotypic, biological and genetic heterogeneity, unknown etiology, and poorly understood alterations in biological pathways and biological mechanisms. Disturbed homeostasis between overproduction of oxidant species, overcoming redox regulation and a lack of cellular antioxidant defenses, resulting in free radical-mediated pathology and subsequent neurotoxicity contributes to development of depression, schizophrenia and PTSD, their heterogeneous clinical presentation and resistance to treatment. Metabolomics is a discipline that combines different strategies with the aim to extract, detect, identify and quantify all metabolites that are present in a biological sample and might provide mechanistic insights into the etiology of various psychiatric disorders. Therefore, oxidative stress research combined with metabolomics might offer a novel approach in dissecting psychiatric disorders, since these data-driven but not necessarily hypothesis-driven methods might identify new targets, molecules and pathways responsible for development of schizophrenia, depression or PTSD. Findings from the oxidative research in psychiatry together with metabolomics data might facilitate development of specific and validated prognostic, therapeutic and clinical biomarkers. These methods might reveal bio-signatures of individual patients, leading to individualized treatment approach. In reviewing findings related to oxidative stress and metabolomics in selected psychiatric disorders, we have highlighted how these novel approaches might make a unique contribution to deeper understanding of psychopathological alterations underlying schizophrenia, depression and PTSD. Keywords: Schizophrenia, Depression, Posttraumatic stress disorder, Oxidative stress, Lipid peroxidation, Metabolomics, Biomarkers

High-energy redox-flow batteries with hybrid metal foam electrodes.

Science.gov (United States)

Park, Min-Sik; Lee, Nam-Jin; Lee, Seung-Wook; Kim, Ki Jae; Oh, Duk-Jin; Kim, Young-Jun

2014-07-09

A nonaqueous redox-flow battery employing [Co(bpy)3](+/2+) and [Fe(bpy)3](2+/3+) redox couples is proposed for use in large-scale energy-storage applications. We successfully demonstrate a redox-flow battery with a practical operating voltage of over 2.1 V and an energy efficiency of 85% through a rational cell design. By utilizing carbon-coated Ni-FeCrAl and Cu metal foam electrodes, the electrochemical reactivity and stability of the nonaqueous redox-flow battery can be considerably enhanced. Our approach intoduces a more efficient conversion of chemical energy into electrical energy and enhances long-term cell durability. The cell exhibits an outstanding cyclic performance of more than 300 cycles without any significant loss of energy efficiency. Considering the increasing demands for efficient energy storage, our achievement provides insight into a possible development pathway for nonaqueous redox-flow batteries with high energy densities.

The Redox Proteome*

Science.gov (United States)

Go, Young-Mi; Jones, Dean P.

2013-01-01

The redox proteome consists of reversible and irreversible covalent modifications that link redox metabolism to biologic structure and function. These modifications, especially of Cys, function at the molecular level in protein folding and maturation, catalytic activity, signaling, and macromolecular interactions and at the macroscopic level in control of secretion and cell shape. Interaction of the redox proteome with redox-active chemicals is central to macromolecular structure, regulation, and signaling during the life cycle and has a central role in the tolerance and adaptability to diet and environmental challenges. PMID:23861437

Approaches towards airport economic performance measurement

Directory of Open Access Journals (Sweden)

Ivana STRYČEKOVÁ

2011-01-01

Full Text Available The paper aims to assess how economic benchmarking is being used by airports as a means of performance measurement and comparison of major international airports in the world. The study focuses on current benchmarking practices and methods by taking into account different factors according to which it is efficient to benchmark airports performance. As methods are considered mainly data envelopment analysis and stochastic frontier analysis. Apart from them other approaches are discussed by airports to provide economic benchmarking. The main objective of this article is to evaluate the efficiency of the airports and answer some undetermined questions involving economic benchmarking of the airports.

Integrating a dual-silicon photoelectrochemical cell into a redox flow battery for unassisted photocharging

DEFF Research Database (Denmark)

Liao, Shichao; Zong, Xu; Seger, Brian

2016-01-01

Solar rechargeable flow cells (SRFCs) provide an attractive approach for in situ capture and storage of intermittent solar energy via photoelectrochemical regeneration of discharged redox species for electricity generation. However, overall SFRC performance is restricted by inefficient photoelect......Solar rechargeable flow cells (SRFCs) provide an attractive approach for in situ capture and storage of intermittent solar energy via photoelectrochemical regeneration of discharged redox species for electricity generation. However, overall SFRC performance is restricted by inefficient...... photoelectrochemical reactions. Here we report an efficient SRFC based on a dual-silicon photoelectrochemical cell and a quinone/bromine redox flow battery for in situ solar energy conversion and storage. Using narrow bandgap silicon for efficient photon collection and fast redox couples for rapid interface charge...

Chloroplast Redox Poise

DEFF Research Database (Denmark)

Steccanella, Verdiana

the redox status of the plastoquinone pool and chlorophyll biosynthesis. Furthermore, in the plant cell, the equilibrium between redox reactions and ROS signals is also maintained by various balancing mechanisms among which the thioredoxin reductase-thioredoxin system (TR-Trx) stands out as a mediator......The redox state of the chloroplast is maintained by a delicate balance between energy production and consumption and is affected by the need to avoid increased production of reactive oxygen species (ROS). Redox power and ROS generated in the chloroplast are essential for maintaining physiological...... metabolic pathways and for optimizing chloroplast functions. The redox poise of photosynthetic electron transport components like plastoquinone is crucial to initiate signaling cascades and might also be involved in key biosynthetic pathways such as chlorophyll biosynthesis. We, therefore, explored...

A generalized approach for the calculation and automation of potentiometric titrations Part 2. Redox Titrations

NARCIS (Netherlands)

Stur, J.; Bos, M.; van der Linden, W.E.

1984-01-01

The very fast calculation procedure described earlier is applied to calculate the titration curves of complicated redox systems. The theory is extended slightly to cover inhomogeneous redox systems. Titrations of iodine or 2,6-dichloroindophenol with ascorbic acid are described. It is shown that

Redox Behavior of Fe2+/Fe3+ Redox Couple by Absorption Spectroscopy and Measurement

International Nuclear Information System (INIS)

Oh, J. Y.; Park, S.; Yun, J. I.

2010-01-01

Redox behavior has influences on speciation and other geochemical reactions of radionuclides such as sorption, solubility, and colloid formation, etc. It is one of the factors for evaluation of long-term safety assessment under high-level radioactive waste (HLW) disposal conditions. Accordingly, redox potential (Eh) measurement in aquatic system is important to investigate the redox conditions. Eh is usually measured with redox active electrodes (Pt, Au, glassy carbon, etc.). Nevertheless, Eh measurements by general methods using electrodes provide low accuracy and high uncertainty problem. Therefore, Eh calculated from the concentration of redox active elements with a proper complexing reagent by using UV-Vis absorption spectroscopy is progressed. Iron exists mostly as spent nuclear waste container material and in hydro-geologic minerals. In this system, iron controls the redox condition in near-field area and influences chemical behavior and speciation of radionuclides including redox sensitive actinides such as U, Np, and Pu. In the present work, we present the investigation on redox phenomena of iron in aquatic system by a combination of absorption spectroscopy and redox potential measurements

Measurement of Redox Potential in Nanoecotoxicological Investigations

Directory of Open Access Journals (Sweden)

Ratna Tantra

2012-01-01

Full Text Available Redox potential has been identified by the Organisation for Economic Co-operation and Development (OECD as one of the parameters that should be investigated for the testing of manufactured nanomaterials. There is still some ambiguity concerning this parameter, i.e., as to what and how to measure, particularly when in a nanoecotoxicological context. In this study the redox potentials of six nanomaterials (either zinc oxide (ZnO or cerium oxide (CeO2 dispersions were measured using an oxidation-reduction potential (ORP electrode probe. The particles under testing differed in terms of their particle size and dispersion stability in deionised water and in various ecotox media. The ORP values of the various dispersions and how they fluctuate relative to each other are discussed. Results show that the ORP values are mainly governed by the type of liquid media employed, with little contributions from the nanoparticles. Seawater was shown to have reduced the ORP value, which was attributed to an increase in the concentration of reducing agents such as sulphites or the reduction of dissolved oxygen concentration. The lack of redox potential value contribution from the particles themselves is thought to be due to insufficient interaction of the particles at the Pt electrode of the ORP probe.

Measurement of redox potential in nanoecotoxicological investigations.

Science.gov (United States)

Tantra, Ratna; Cackett, Alex; Peck, Roger; Gohil, Dipak; Snowden, Jacqueline

2012-01-01

Redox potential has been identified by the Organisation for Economic Co-operation and Development (OECD) as one of the parameters that should be investigated for the testing of manufactured nanomaterials. There is still some ambiguity concerning this parameter, i.e., as to what and how to measure, particularly when in a nanoecotoxicological context. In this study the redox potentials of six nanomaterials (either zinc oxide (ZnO) or cerium oxide (CeO(2))) dispersions were measured using an oxidation-reduction potential (ORP) electrode probe. The particles under testing differed in terms of their particle size and dispersion stability in deionised water and in various ecotox media. The ORP values of the various dispersions and how they fluctuate relative to each other are discussed. Results show that the ORP values are mainly governed by the type of liquid media employed, with little contributions from the nanoparticles. Seawater was shown to have reduced the ORP value, which was attributed to an increase in the concentration of reducing agents such as sulphites or the reduction of dissolved oxygen concentration. The lack of redox potential value contribution from the particles themselves is thought to be due to insufficient interaction of the particles at the Pt electrode of the ORP probe.

Redox Potentials of Ligands and Complexes – a DFT Approach

African Journals Online (AJOL)

NICO

A review of the limited literature concerned with theoretical ways to predict experimentally measured redox potentials of ligands and ... electrode surface, over-potentials and high solvent resistance, ... A correlation coefficient of 0.969 in the linear relation with ... of E0' were performed in two steps, i.e. calculation of the free.

Economic approach of the environment and environmental conservation

International Nuclear Information System (INIS)

Verbruggen, A.

2008-01-01

This book takes the non-economist by the hand in a step-by-step economic approach of environmental issues and how to handle them. Two chapters provide an introduction to the concepts of the economy, chapter six in decision theory. In the first chapter, the economist discovers a broader vision by testing the economic approach to insights from other disciplines. Chapter 4 explains how economic reasoning can contribute tot environmental protection in practice. The consideration of the costs and benefits of environmental protection indicates objectives that must be pursued for the community. The conflict between private and public interest forces policy makers to get and maintain the numerous polluters focused on environmental protection. Suitable instruments are discussed in chapter five, including criteria for choice and an in-depth study of the economic instruments levies and tradable emission permits. The EU Emission trading Scheme is used as reference. [mk] [nl

Redox sensor proteins for highly sensitive direct imaging of intracellular redox state.

Science.gov (United States)

Sugiura, Kazunori; Nagai, Takeharu; Nakano, Masahiro; Ichinose, Hiroshi; Nakabayashi, Takakazu; Ohta, Nobuhiro; Hisabori, Toru

2015-02-13

Intracellular redox state is a critical factor for fundamental cellular functions, including regulation of the activities of various metabolic enzymes as well as ROS production and elimination. Genetically-encoded fluorescent redox sensors, such as roGFP (Hanson, G. T., et al. (2004)) and Redoxfluor (Yano, T., et al. (2010)), have been developed to investigate the redox state of living cells. However, these sensors are not useful in cells that contain, for example, other colored pigments. We therefore intended to obtain simpler redox sensor proteins, and have developed oxidation-sensitive fluorescent proteins called Oba-Q (oxidation balance sensed quenching) proteins. Our sensor proteins derived from CFP and Sirius can be used to monitor the intracellular redox state as their fluorescence is drastically quenched upon oxidation. These blue-shifted spectra of the Oba-Q proteins enable us to monitor various redox states in conjunction with other sensor proteins. Copyright © 2015 Elsevier Inc. All rights reserved.

Study to establish cost predictions for the production of Redox chemicals

Science.gov (United States)

Ammann, P. R.; Loreth, M.; Harvey, W. W.

1982-01-01

The chromium and iron chloride chemicals are significant first costs for NASA Redox energy storage systems. This study was performed to determine the lowest cost at which chromium and iron chlorides could be obtained for a complex of redox energy storage systems. In addition, since the solutions gradually become intermixed during the course of operation of Redox units, it was an objective to evaluate schemes for regeneration of the operating solutions. Three processes were evaluated for the production of chromium and iron chlorides. As a basis for the preliminary plant design and economic evaluation, it was assumed that the plant would produce about 25,000 tons of contained chromium as CrCl3 and an equivalent molar quantity of FeCl2. Preliminary plant designs, including materials and energy balances and sizing of major equipment, were prepared, and capital and operating costs were estimated.

Redox Regulation of Mitochondrial Function

Science.gov (United States)

Handy, Diane E.

2012-01-01

Abstract Redox-dependent processes influence most cellular functions, such as differentiation, proliferation, and apoptosis. Mitochondria are at the center of these processes, as mitochondria both generate reactive oxygen species (ROS) that drive redox-sensitive events and respond to ROS-mediated changes in the cellular redox state. In this review, we examine the regulation of cellular ROS, their modes of production and removal, and the redox-sensitive targets that are modified by their flux. In particular, we focus on the actions of redox-sensitive targets that alter mitochondrial function and the role of these redox modifications on metabolism, mitochondrial biogenesis, receptor-mediated signaling, and apoptotic pathways. We also consider the role of mitochondria in modulating these pathways, and discuss how redox-dependent events may contribute to pathobiology by altering mitochondrial function. Antioxid. Redox Signal. 16, 1323–1367. PMID:22146081

Connecting Biology to Electronics: Molecular Communication via Redox Modality.

Science.gov (United States)

Liu, Yi; Li, Jinyang; Tschirhart, Tanya; Terrell, Jessica L; Kim, Eunkyoung; Tsao, Chen-Yu; Kelly, Deanna L; Bentley, William E; Payne, Gregory F

2017-12-01

Biology and electronics are both expert at for accessing, analyzing, and responding to information. Biology uses ions, small molecules, and macromolecules to receive, analyze, store, and transmit information, whereas electronic devices receive input in the form of electromagnetic radiation, process the information using electrons, and then transmit output as electromagnetic waves. Generating the capabilities to connect biology-electronic modalities offers exciting opportunities to shape the future of biosensors, point-of-care medicine, and wearable/implantable devices. Redox reactions offer unique opportunities for bio-device communication that spans the molecular modalities of biology and electrical modality of devices. Here, an approach to search for redox information through an interactive electrochemical probing that is analogous to sonar is adopted. The capabilities of this approach to access global chemical information as well as information of specific redox-active chemical entities are illustrated using recent examples. An example of the use of synthetic biology to recognize external molecular information, process this information through intracellular signal transduction pathways, and generate output responses that can be detected by electrical modalities is also provided. Finally, exciting results in the use of redox reactions to actuate biology are provided to illustrate that synthetic biology offers the potential to guide biological response through electrical cues. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An Excel Workbook for Identifying Redox Processes in Ground Water

Science.gov (United States)

Jurgens, Bryant C.; McMahon, Peter B.; Chapelle, Francis H.; Eberts, Sandra M.

2009-01-01

The reduction/oxidation (redox) condition of ground water affects the concentration, transport, and fate of many anthropogenic and natural contaminants. The redox state of a ground-water sample is defined by the dominant type of reduction/oxidation reaction, or redox process, occurring in the sample, as inferred from water-quality data. However, because of the difficulty in defining and applying a systematic redox framework to samples from diverse hydrogeologic settings, many regional water-quality investigations do not attempt to determine the predominant redox process in ground water. Recently, McMahon and Chapelle (2008) devised a redox framework that was applied to a large number of samples from 15 principal aquifer systems in the United States to examine the effect of redox processes on water quality. This framework was expanded by Chapelle and others (in press) to use measured sulfide data to differentiate between iron(III)- and sulfate-reducing conditions. These investigations showed that a systematic approach to characterize redox conditions in ground water could be applied to datasets from diverse hydrogeologic settings using water-quality data routinely collected in regional water-quality investigations. This report describes the Microsoft Excel workbook, RedoxAssignment_McMahon&Chapelle.xls, that assigns the predominant redox process to samples using the framework created by McMahon and Chapelle (2008) and expanded by Chapelle and others (in press). Assignment of redox conditions is based on concentrations of dissolved oxygen (O2), nitrate (NO3-), manganese (Mn2+), iron (Fe2+), sulfate (SO42-), and sulfide (sum of dihydrogen sulfide [aqueous H2S], hydrogen sulfide [HS-], and sulfide [S2-]). The logical arguments for assigning the predominant redox process to each sample are performed by a program written in Microsoft Visual Basic for Applications (VBA). The program is called from buttons on the main worksheet. The number of samples that can be analyzed

Redox Signaling in Diabetic Wound Healing Regulates Extracellular Matrix Deposition.

Science.gov (United States)

Kunkemoeller, Britta; Kyriakides, Themis R

2017-10-20

Impaired wound healing is a major complication of diabetes, and can lead to development of chronic foot ulcers in a significant number of patients. Despite the danger posed by poor healing, very few specific therapies exist, leaving patients at risk of hospitalization, amputation, and further decline in overall health. Recent Advances: Redox signaling is a key regulator of wound healing, especially through its influence on the extracellular matrix (ECM). Normal redox signaling is disrupted in diabetes leading to several pathological mechanisms that alter the balance between reactive oxygen species (ROS) generation and scavenging. Importantly, pathological oxidative stress can alter ECM structure and function. There is limited understanding of the specific role of altered redox signaling in the diabetic wound, although there is evidence that ROS are involved in the underlying pathology. Preclinical studies of antioxidant-based therapies for diabetic wound healing have yielded promising results. Redox-based therapeutics constitute a novel approach for the treatment of wounds in diabetes patients that deserve further investigation. Antioxid. Redox Signal. 27, 823-838.

A redox-flow battery with an alloxazine-based organic electrolyte

Science.gov (United States)

Lin, Kaixiang; Gómez-Bombarelli, Rafael; Beh, Eugene S.; Tong, Liuchuan; Chen, Qing; Valle, Alvaro; Aspuru-Guzik, Alán; Aziz, Michael J.; Gordon, Roy G.

2016-09-01

Redox-flow batteries (RFBs) can store large amounts of electrical energy from variable sources, such as solar and wind. Recently, redox-active organic molecules in aqueous RFBs have drawn substantial attention due to their rapid kinetics and low membrane crossover rates. Drawing inspiration from nature, here we report a high-performance aqueous RFB utilizing an organic redox compound, alloxazine, which is a tautomer of the isoalloxazine backbone of vitamin B2. It can be synthesized in high yield at room temperature by single-step coupling of inexpensive o-phenylenediamine derivatives and alloxan. The highly alkaline-soluble alloxazine 7/8-carboxylic acid produces a RFB exhibiting open-circuit voltage approaching 1.2 V and current efficiency and capacity retention exceeding 99.7% and 99.98% per cycle, respectively. Theoretical studies indicate that structural modification of alloxazine with electron-donating groups should allow further increases in battery voltage. As an aza-aromatic molecule that undergoes reversible redox cycling in aqueous electrolyte, alloxazine represents a class of radical-free redox-active organics for use in large-scale energy storage.

Decision Making under Ecological Regime Shift: An Experimental Economic Approach

OpenAIRE

Kawata, Yukichika

2011-01-01

Environmental economics postulates the assumption of homo economicus and presumes that externality occurs as a result of the rational economic activities of economic agents. This paper examines this assumption using an experimental economic approach in the context of regime shift, which has been receiving increasing attention. We observe that when externality does not exist, economic agents (subjects of experimemt) act economically rationally, but when externality exists, economic agents avoi...

Redox signaling in plants.

Science.gov (United States)

Foyer, Christine H; Noctor, Graham

2013-06-01

Our aim is to deliver an authoritative and challenging perspective of current concepts in plant redox signaling, focusing particularly on the complex interface between the redox and hormone-signaling pathways that allow precise control of plant growth and defense in response to metabolic triggers and environmental constraints and cues. Plants produce significant amounts of singlet oxygen and other reactive oxygen species (ROS) as a result of photosynthetic electron transport and metabolism. Such pathways contribute to the compartment-specific redox-regulated signaling systems in plant cells that convey information to the nucleus to regulate gene expression. Like the chloroplasts and mitochondria, the apoplast-cell wall compartment makes a significant contribution to the redox signaling network, but unlike these organelles, the apoplast has a low antioxidant-buffering capacity. The respective roles of ROS, low-molecular antioxidants, redox-active proteins, and antioxidant enzymes are considered in relation to the functions of plant hormones such as salicylic acid, jasmonic acid, and auxin, in the composite control of plant growth and defense. Regulation of redox gradients between key compartments in plant cells such as those across the plasma membrane facilitates flexible and multiple faceted opportunities for redox signaling that spans the intracellular and extracellular environments. In conclusion, plants are recognized as masters of the art of redox regulation that use oxidants and antioxidants as flexible integrators of signals from metabolism and the environment.

Economic analysis of a new class of vanadium redox-flow battery for medium- and large-scale energy storage in commercial applications with renewable energy

International Nuclear Information System (INIS)

Li, Ming-Jia; Zhao, Wei; Chen, Xi; Tao, Wen-Quan

2017-01-01

Highlights: • A new class of the vanadium redox-flow battery (VRB) is developed. • The new class of VRB is more economic. It is simple process and easy to scale-up. • There are three levels of cell stacks and electrolytes with different qualities. • The economic analysis of the VRB system for renewable energy bases is carried out. • Related polices and suggestions based on the result are provided. - Abstract: Interest in the implement of vanadium redox-flow battery (VRB) for energy storage is growing, which is widely applicable to large-scale renewable energy (e.g. wind energy and solar photo-voltaic), developing distributed generation, lowering the imbalance and increasing the usage of electricity. However, a comprehensive economic analysis of the VRB for energy storage is obscured for various commercial applications, yet it is fundamental for implementation of the VRB in commercial electricity markets. In this study, based on a new class of the VRB that was developed by our team, a comprehensive economic analysis of the VRB for large-scale energy storage is carried out. The results illustrate the economy of the VRB applications for three typical energy systems: (1) The VRB storage system instead of the normal lead-acid battery to be the uninterrupted power supply (UPS) battery for office buildings and hospitals; (2) Application of vanadium battery in household distributed photo-voltaic power generation systems; (3) The wind power and solar power stations equipped with the VRB storage systems. The economic perspectives and cost-benefit analysis of the VRB storage systems may underpin optimisation for maximum profitability. In this case, two findings are concluded. First, with the fixed capacity power or fixed discharging time, the greater profit ratio will be generated from the longer time or the larger capacity power. Second, when the profit ratio, discharging time and capacity power are all variables, it is necessary to find out the best optimisation

Catechol-chitosan redox capacitor for added amplification in electrochemical immunoanalysis.

Science.gov (United States)

Yan, Kun; Liu, Yi; Guan, Yongguang; Bhokisham, Narendranath; Tsao, Chen-Yu; Kim, Eunkyoung; Shi, Xiao-Wen; Wang, Qin; Bentley, William E; Payne, Gregory F

2018-05-22

Antibodies are common recognition elements for molecular detection but often the signals generated by their stoichiometric binding must be amplified to enhance sensitivity. Here, we report that an electrode coated with a catechol-chitosan redox capacitor can amplify the electrochemical signal generated from an alkaline phosphatase (AP) linked immunoassay. Specifically, the AP product p-aminophenol (PAP) undergoes redox-cycling in the redox capacitor to generate amplified oxidation currents. We estimate an 8-fold amplification associated with this redox-cycling in the capacitor (compared to detection by a bare electrode). Importantly, this capacitor-based amplification is generic and can be coupled to existing amplification approaches based on enzyme-linked catalysis or magnetic nanoparticle-based collection/concentration. Thus, the capacitor should enhance sensitivities in conventional immunoassays and also provide chemical to electrical signal transduction for emerging applications in molecular communication. Copyright © 2018 Elsevier B.V. All rights reserved.

Integrated approach to economical, reliable, safe nuclear power production

International Nuclear Information System (INIS)

1982-06-01

An Integrated Approach to Economical, Reliable, Safe Nuclear Power Production is the latest evolution of a concept which originated with the Defense-in-Depth philosophy of the nuclear industry. As Defense-in-Depth provided a framework for viewing physical barriers and equipment redundancy, the Integrated Approach gives a framework for viewing nuclear power production in terms of functions and institutions. In the Integrated Approach, four plant Goals are defined (Normal Operation, Core and Plant Protection, Containment Integrity and Emergency Preparedness) with the attendant Functional and Institutional Classifications that support them. The Integrated Approach provides a systematic perspective that combines the economic objective of reliable power production with the safety objective of consistent, controlled plant operation

A Discrete Monetary Economic Growth Model with the MIU Approach

Directory of Open Access Journals (Sweden)

Wei-Bin Zhang

2008-01-01

Full Text Available This paper proposes an alternative approach to economic growth with money. The production side is the same as the Solow model, the Ramsey model, and the Tobin model. But we deal with behavior of consumers differently from the traditional approaches. The model is influenced by the money-in-the-utility (MIU approach in monetary economics. It provides a mechanism of endogenous saving which the Solow model lacks and avoids the assumption of adding up utility over a period of time upon which the Ramsey approach is based.

Thermodynamic and redox properties of graphene oxides for lithium-ion battery applications: a first principles density functional theory modeling approach.

Science.gov (United States)

Kim, Sunghee; Kim, Ki Chul; Lee, Seung Woo; Jang, Seung Soon

2016-07-27

Understanding the thermodynamic stability and redox properties of oxygen functional groups on graphene is critical to systematically design stable graphene-based positive electrode materials with high potential for lithium-ion battery applications. In this work, we study the thermodynamic and redox properties of graphene functionalized with carbonyl and hydroxyl groups, and the evolution of these properties with the number, types and distribution of functional groups by employing the density functional theory method. It is found that the redox potential of the functionalized graphene is sensitive to the types, number, and distribution of oxygen functional groups. First, the carbonyl group induces higher redox potential than the hydroxyl group. Second, more carbonyl groups would result in higher redox potential. Lastly, the locally concentrated distribution of the carbonyl group is more beneficial to have higher redox potential compared to the uniformly dispersed distribution. In contrast, the distribution of the hydroxyl group does not affect the redox potential significantly. Thermodynamic investigation demonstrates that the incorporation of carbonyl groups at the edge of graphene is a promising strategy for designing thermodynamically stable positive electrode materials with high redox potentials.

Feminist Development Economics : An Institutional Approach to Household Analysis

NARCIS (Netherlands)

I.P. van Staveren (Irene); O. Odebode (Olasunbo)

2014-01-01

markdownabstract__Abstract__ In this chapter, we argue that an institutional approach to feminist development economics provides deeper understandings to how gender inequalities function in economic processes in developing countries. We do this in three ways. First, we distinguish between

Recent developments in organic redox flow batteries: A critical review

Science.gov (United States)

Leung, P.; Shah, A. A.; Sanz, L.; Flox, C.; Morante, J. R.; Xu, Q.; Mohamed, M. R.; Ponce de León, C.; Walsh, F. C.

2017-08-01

Redox flow batteries (RFBs) have emerged as prime candidates for energy storage on the medium and large scales, particularly at the grid scale. The demand for versatile energy storage continues to increase as more electrical energy is generated from intermittent renewable sources. A major barrier in the way of broad deployment and deep market penetration is the use of expensive metals as the active species in the electrolytes. The use of organic redox couples in aqueous or non-aqueous electrolytes is a promising approach to reducing the overall cost in long-term, since these materials can be low-cost and abundant. The performance of such redox couples can be tuned by modifying their chemical structure. In recent years, significant developments in organic redox flow batteries has taken place, with the introduction of new groups of highly soluble organic molecules, capable of providing a cell voltage and charge capacity comparable to conventional metal-based systems. This review summarises the fundamental developments and characterization of organic redox flow batteries from both the chemistry and materials perspectives. The latest advances, future challenges and opportunities for further development are discussed.

Analysis of redox additive-based overcharge protection for rechargeable lithium batteries

Science.gov (United States)

Narayanan, S. R.; Surampudi, S.; Attia, A. I.; Bankston, C. P.

1991-01-01

The overcharge condition in secondary lithium batteries employing redox additives for overcharge protection, has been theoretically analyzed in terms of a finite linear diffusion model. The analysis leads to expressions relating the steady-state overcharge current density and cell voltage to the concentration, diffusion coefficient, standard reduction potential of the redox couple, and interelectrode distance. The model permits the estimation of the maximum permissible overcharge rate for any chosen set of system conditions. Digital simulation of the overcharge experiment leads to numerical representation of the potential transients, and estimate of the influence of diffusion coefficient and interelectrode distance on the transient attainment of the steady state during overcharge. The model has been experimentally verified using 1,1-prime-dimethyl ferrocene as a redox additive. The analysis of the experimental results in terms of the theory allows the calculation of the diffusion coefficient and the formal potential of the redox couple. The model and the theoretical results may be exploited in the design and optimization of overcharge protection by the redox additive approach.

Is Oxidized Thioredoxin a Major Trigger for Cysteine Oxidation? Clues from a Redox Proteomics Approach

OpenAIRE

García-Santamarina, Sarela; Boronat, Susanna; Calvo, Isabel A.; Rodríguez-Gabriel, Miguel; Ayté, José; Molina, Henrik; Hidalgo, Elena

2013-01-01

This is a copy of an article published in the Antioxidants & Redox Signaling © Mary Ann Liebert, Inc. Antioxidants & Redox Signaling is available online at http://online.liebertpub.com Cysteine oxidation mediates oxidative stress toxicity and signaling. It has been long proposed that the thioredoxin (Trx) system, which consists of Trx and thioredoxin reductase (Trr), is not only involved in recycling classical Trx substrates, such as ribonucleotide reductase, but it also regulates g...

Effect of long-term fertilization on humic redox mediators in multiple microbial redox reactions.

Science.gov (United States)

Guo, Peng; Zhang, Chunfang; Wang, Yi; Yu, Xinwei; Zhang, Zhichao; Zhang, Dongdong

2018-03-01

This study investigated the effects of different long-term fertilizations on humic substances (HSs), humic acids (HAs) and humins, functioning as redox mediators for various microbial redox biotransformations, including 2,2',4,4',5,5'- hexachlorobiphenyl (PCB 153 ) dechlorination, dissimilatory iron reduction, and nitrate reduction, and their electron-mediating natures. The redox activity of HSs for various microbial redox metabolisms was substantially enhanced by long-term application of organic fertilizer (pig manure). As a redox mediator, only humin extracted from soils with organic fertilizer amendment (OF-HM) maintained microbial PCB 153 dechlorination activity (1.03 μM PCB 153 removal), and corresponding HA (OF-HA) most effectively enhanced iron reduction and nitrate reduction by Shewanella putrefaciens. Electrochemical analysis confirmed the enhancement of their electron transfer capacity and redox properties. Fourier transform infrared analysis showed that C=C and C=O bonds, and carboxylic or phenolic groups in HSs might be the redox functional groups affected by fertilization. This research enhances our understanding of the influence of anthropogenic fertility on the biogeochemical cycling of elements and in situ remediation ability in agroecosystems through microorganisms' metabolisms. Copyright © 2017 Elsevier Ltd. All rights reserved.

Strategies for "wiring" redox-active proteins to electrodes and applications in biosensors, biofuel cells, and nanotechnology.

Science.gov (United States)

Nöll, Tanja; Nöll, Gilbert

2011-07-01

In this tutorial review the basic approaches to establish electrochemical communication between redox-active proteins and electrodes are elucidated and examples for applications in electrochemical biosensors, biofuel cells and nanotechnology are presented. The early stage of protein electrochemistry is described giving a short overview over electron transfer (ET) between electrodes and proteins, followed by a brief introduction into experimental procedures for studying proteins at electrodes and possible applications arising thereof. The article starts with discussing the electrochemistry of cytochrome c, the first redox-active protein, for which direct reversible ET was obtained, under diffusion controlled conditions and after adsorption to electrodes. Next, examples for the electrochemical study of redox enzymes adsorbed on electrodes and modes of immobilization are discussed. Shortly the experimental approach for investigating redox-active proteins adsorbed on electrodes is outlined. Possible applications of redox enzymes in electrochemical biosensors and biofuel cells working by direct ET (DET) and mediated ET (MET) are presented. Furthermore, the reconstitution of redox active proteins at electrodes using molecular wire-like units in order to "wire" the proteins to the electrode surface and possible applications in nanotechnology are discussed.

REDOX IMAGING OF THE p53-DEPENDENT MITOCHONDRIAL REDOX STATE IN COLON CANCER EX VIVO

Science.gov (United States)

XU, HE N.; FENG, MIN; MOON, LILY; DOLLOFF, NATHAN; EL-DEIRY, WAFIK; LI, LIN Z.

2015-01-01

The mitochondrial redox state and its heterogeneity of colon cancer at tissue level have not been previously reported. Nor has how p53 regulates mitochondrial respiration been measured at (deep) tissue level, presumably due to the unavailability of the technology that has sufficient spatial resolution and tissue penetration depth. Our prior work demonstrated that the mitochondrial redox state and its intratumor heterogeneity is associated with cancer aggressiveness in human melanoma and breast cancer in mouse models, with the more metastatic tumors exhibiting localized regions of more oxidized redox state. Using the Chance redox scanner with an in-plane spatial resolution of 200 μm, we imaged the mitochondrial redox state of the wild-type p53 colon tumors (HCT116 p53 wt) and the p53-deleted colon tumors (HCT116 p53−/−) by collecting the fluorescence signals of nicotinamide adenine dinucleotide (NADH) and oxidized flavoproteins [Fp, including flavin adenine dinucleotide (FAD)] from the mouse xenografts snap-frozen at low temperature. Our results show that: (1) both tumor lines have significant degree of intratumor heterogeneity of the redox state, typically exhibiting a distinct bi-modal distribution that either correlates with the spatial core–rim pattern or the “hot/cold” oxidation-reduction patches; (2) the p53−/− group is significantly more heterogeneous in the mitochondrial redox state and has a more oxidized tumor core compared to the p53 wt group when the tumor sizes of the two groups are matched; (3) the tumor size dependence of the redox indices (such as Fp and Fp redox ratio) is significant in the p53−/− group with the larger ones being more oxidized and more heterogeneous in their redox state, particularly more oxidized in the tumor central regions; (4) the H&E staining images of tumor sections grossly correlate with the redox images. The present work is the first to reveal at the submillimeter scale the intratumor heterogeneity pattern

The Strategically Oriented Approach to Studying the Economic Sustainability of Enterprises

Directory of Open Access Journals (Sweden)

Ponomarenko Tеtyana V.

2017-03-01

Full Text Available The article presents the constructive consideration of modern approaches to the study of the essence of economic sustainability. It is noted that they are focused on sustainability as a status of the economic system. It is actualized that such an approach does not correspond to the system-synergetic methodology, according to which sustainability has a dualistic nature: as a status and as a property of the system to be stable. The key provisions of the traditional approach to understanding the essence of economic sustainability are systematized. Based on the productive synthesis of the system-synergetic methodology and modern achievements of the theory of strategic management, there formed the author’s conceptual approach that extends the traditional content of economic sustainability exclusively as a status. The proposed approach extends the temporal context of sustainability from the provision of a momentary state to the formation of the possibilities for the permanent functioning of an enterprise. It is argued that these opportunities are determined by the organizational ability of companies to realize their functional purpose. This changes the priority of the managerial focus: from orientation to providing material, financial and labor resources (the traditional approach to the accumulation of resources that can not be the subject of market-based sales transactions (the strategically oriented approach.

A compartmentalized solute transport model for redox zones in contaminated aquifers: 1. Theory and development

Science.gov (United States)

Abrams , Robert H.; Loague, Keith

2000-01-01

This paper, the first of two parts [see Abrams and Loague, this issue], takes the compartmentalized approach for the geochemical evolution of redox zones presented by Abrams et al. [1998] and embeds it within a solute transport framework. In this paper the compartmentalized approach is generalized to facilitate the description of its incorporation into a solute transport simulator. An equivalent formulation is developed which removes any discontinuities that may occur when switching compartments. Rate‐limited redox reactions are modeled with a modified Monod relationship that allows either the organic substrate or the electron acceptor to be the rate‐limiting reactant. Thermodynamic constraints are used to inhibit lower‐energy redox reactions from occurring under infeasible geochemical conditions without imposing equilibrium on the lower‐energy reactions. The procedure used allows any redox reaction to be simulated as being kinetically limited or thermodynamically limited, depending on local geochemical conditions. Empirical reaction inhibition methods are not needed. The sequential iteration approach (SIA), a technique which allows the number of solute transport equations to be reduced, is adopted to solve the coupled geochemical/solute transport problem. When the compartmentalized approach is embedded within the SIA, with the total analytical concentration of each component as the dependent variable in the transport equation, it is possible to reduce the number of transport equations even further than with the unmodified SIA. A one‐dimensional, coupled geochemical/solute transport simulation is presented in which redox zones evolve dynamically in time and space. The compartmentalized solute transport (COMPTRAN) model described in this paper enables the development of redox zones to be simulated under both kinetic and thermodynamic constraints. The modular design of COMPTRAN facilitates the use of many different, preexisting solute transport and

Redox Pioneer: Professor Vadim N. Gladyshev.

Science.gov (United States)

Hatfield, Dolph L

2016-07-01

Professor Vadim N. Gladyshev is recognized here as a Redox Pioneer, because he has published an article on antioxidant/redox biology that has been cited more than 1000 times and 29 articles that have been cited more than 100 times. Gladyshev is world renowned for his characterization of the human selenoproteome encoded by 25 genes, identification of the majority of known selenoprotein genes in the three domains of life, and discoveries related to thiol oxidoreductases and mechanisms of redox control. Gladyshev's first faculty position was in the Department of Biochemistry, the University of Nebraska. There, he was a Charles Bessey Professor and Director of the Redox Biology Center. He then moved to the Department of Medicine at Brigham and Women's Hospital, Harvard Medical School, where he is Professor of Medicine and Director of the Center for Redox Medicine. His discoveries in redox biology relate to selenoenzymes, such as methionine sulfoxide reductases and thioredoxin reductases, and various thiol oxidoreductases. He is responsible for the genome-wide identification of catalytic redox-active cysteines and for advancing our understanding of the general use of cysteines by proteins. In addition, Gladyshev has characterized hydrogen peroxide metabolism and signaling and regulation of protein function by methionine-R-sulfoxidation. He has also made important contributions in the areas of aging and lifespan control and pioneered applications of comparative genomics in redox biology, selenium biology, and aging. Gladyshev's discoveries have had a profound impact on redox biology and the role of redox control in health and disease. He is a true Redox Pioneer. Antioxid. Redox Signal. 25, 1-9.

A new approach to design safe CNTs with an understanding of redox potential.

Science.gov (United States)

Tsuruoka, Shuji; Cassee, Flemming R; Castranova, Vincent

2013-09-02

Carbon nanotubes (CNTs) are being increasingly industrialized and applied for various products. As of today, although several toxicological evaluations of CNTs have been conducted, designing safer CNTs is not practiced because reaction kinetics of CNTs with bioactive species is not fully understood. The authors propose a kinetic mechanism to establish designing safe CNTs as a new goal. According to a literature search on the behavior of CNTs and the effects of impurities, it is found that chemical reactions on CNT surface are attributed to redox reactions involving metal impurities and carbon structures at the CNT surface. A new goal is proposed to design safer CNTs using the redox potential hypothesis. The value of this hypothesis must be practically investigated and proven through the further experiments.

Species-Specific Thiol-Disulfide Equilibrium Constant: A Tool To Characterize Redox Transitions of Biological Importance.

Science.gov (United States)

Mirzahosseini, Arash; Somlyay, Máté; Noszál, Béla

2015-08-13

Microscopic redox equilibrium constants, a new species-specific type of physicochemical parameters, were introduced and determined to quantify thiol-disulfide equilibria of biological significance. The thiol-disulfide redox equilibria of glutathione with cysteamine, cysteine, and homocysteine were approached from both sides, and the equilibrium mixtures were analyzed by quantitative NMR methods to characterize the highly composite, co-dependent acid-base and redox equilibria. The directly obtained, pH-dependent, conditional constants were then decomposed by a new evaluation method, resulting in pH-independent, microscopic redox equilibrium constants for the first time. The 80 different, microscopic redox equilibrium constant values show close correlation with the respective thiolate basicities and provide sound means for the development of potent agents against oxidative stress.

Development and testing of a compartmentalized reaction network model for redox zones in contaminated aquifers

Science.gov (United States)

Abrams , Robert H.; Loague, Keith; Kent, Douglas B.

1998-01-01

The work reported here is the first part of a larger effort focused on efficient numerical simulation of redox zone development in contaminated aquifers. The sequential use of various electron acceptors, which is governed by the energy yield of each reaction, gives rise to redox zones. The large difference in energy yields between the various redox reactions leads to systems of equations that are extremely ill-conditioned. These equations are very difficult to solve, especially in the context of coupled fluid flow, solute transport, and geochemical simulations. We have developed a general, rational method to solve such systems where we focus on the dominant reactions, compartmentalizing them in a manner that is analogous to the redox zones that are often observed in the field. The compartmentalized approach allows us to easily solve a complex geochemical system as a function of time and energy yield, laying the foundation for our ongoing work in which we couple the reaction network, for the development of redox zones, to a model of subsurface fluid flow and solute transport. Our method (1) solves the numerical system without evoking a redox parameter, (2) improves the numerical stability of redox systems by choosing which compartment and thus which reaction network to use based upon the concentration ratios of key constituents, (3) simulates the development of redox zones as a function of time without the use of inhibition factors or switching functions, and (4) can reduce the number of transport equations that need to be solved in space and time. We show through the use of various model performance evaluation statistics that the appropriate compartment choice under different geochemical conditions leads to numerical solutions without significant error. The compartmentalized approach described here facilitates the next phase of this effort where we couple the redox zone reaction network to models of fluid flow and solute transport.

Economic evaluation of multilateral nuclear fuel cycle approach

International Nuclear Information System (INIS)

Takashima, Ryuta; Kuno, Yusuke; Omoto, Akira; Tanaka, Satoru

2011-01-01

Recently previous works have shown that multilateral nuclear fuel cycle approach has benefits not only of non-proliferation but also of cost effectiveness. This is because for most facilities in nuclear fuel cycle, there exist economies of scale, which has a significant impact on the costs of nuclear fuel cycle. Therefore, the evaluation of economic rationality is required as one of the evaluation factors for the multilateral nuclear fuel cycle approach. In this study, we consider some options with respect to multilateral approaches to nuclear fuel cycle in Asian-Pacific region countries that are proposed by the University of Tokyo. In particular, the following factors are embedded into each type: A) no involvement of assurance of services, B) provision of assurance of services including construction of new facility, without transfer of ownership, and C) provision of assurance of service including construction of new joint facilities with ownership transfer of facilities to multilateral nuclear fuel cycle approach. We show the overnight costs taking into account install and operation of nuclear fuel cycle facilities for each option. The economic parameter values such as uranium price, scale factor, and market output expansion influences the total cost for each option. Thus, we show how these parameter values and economic risks affect the total overnight costs for each option. Additionally, the international facilities could increase the risk of transportation for nuclear material compared to national facilities. We discuss the potential effects of this transportation risk on the costs for each option. (author)

Computational assignment of redox states to Coulomb blockade diamonds.

Science.gov (United States)

Olsen, Stine T; Arcisauskaite, Vaida; Hansen, Thorsten; Kongsted, Jacob; Mikkelsen, Kurt V

2014-09-07

With the advent of molecular transistors, electrochemistry can now be studied at the single-molecule level. Experimentally, the redox chemistry of the molecule manifests itself as features in the observed Coulomb blockade diamonds. We present a simple theoretical method for explicit construction of the Coulomb blockade diamonds of a molecule. A combined quantum mechanical/molecular mechanical method is invoked to calculate redox energies and polarizabilities of the molecules, including the screening effect of the metal leads. This direct approach circumvents the need for explicit modelling of the gate electrode. From the calculated parameters the Coulomb blockade diamonds are constructed using simple theory. We offer a theoretical tool for assignment of Coulomb blockade diamonds to specific redox states in particular, and a study of chemical details in the diamonds in general. With the ongoing experimental developments in molecular transistor experiments, our tool could find use in molecular electronics, electrochemistry, and electrocatalysis.

Redox Species-Based Electrolytes for Advanced Rechargeable Lithium Ion Batteries

KAUST Repository

Ming, Jun

2016-08-15

Seeking high-capacity cathodes has become an intensive effort in lithium ion battery research; however, the low energy density still remains a major issue for sustainable handheld devices and vehicles. Herein, we present a new strategy of integrating a redox species-based electrolyte in batteries to boost their performance. Taking the olivine LiFePO4-based battery as an example, the incorporation of redox species (i.e., polysulfide of Li2S8) in the electrolyte results in much lower polarization and superior stability, where the dissociated Li+/Sx2– can significantly speed up the lithium diffusion. More importantly, the presence of the S82–/S2– redox reaction further contributes extra capacity, making a completely new LiFePO4/Li2Sx hybrid battery with a high energy density of 1124 Wh kgcathode–1 and a capacity of 442 mAh gcathode–1. The marriage of appropriate redox species in an electrolyte for a rechargeable battery is an efficient and scalable approach for obtaining higher energy density storage devices.

Redox flow batteries. Already an alternative storage solution for hybrid PV mini-grids?

Energy Technology Data Exchange (ETDEWEB)

Vetter, Matthias; Dennenmoser, Martin; Schwunk, Simon; Smolinka, Tom [Fraunhofer Institute for Solar Energy Systems (ISE), Freiburg (Germany); Doetsch, Christian; Berthold, Sascha [Fraunhofer Institute for Environmental, Safety and Energy Technology (UMSICHT), Oberhausen (Germany); Tuebke, Jens; Noack, Jens [Fraunhofer Institute for Chemical Technology (ICT), Karlsruhe (Germany)

2010-07-01

Due to the flexible scalability of the power to energy ratio redox flow batteries are a suitable solution for quite a lot of decentralized applications. E.g. the autonomy time of a stand-alone system or mini-grid can be raised by increasing the tank size of the redox flow battery. In this paper the test site ''Rappenecker Hof'' in the black forest is used as an example for simulation based life cycle cost analyses of a vanadium redox flow battery integrated in an autonomous hybrid PV system. Two cases with lead acid batteries are considered as benchmarks for economic viability of the redox flow battery solution in such applications. At the moment a 1 KW / 6 kWh system for decentralized solutions is developed and will be installed in the ''Solarhaus'' in Freiburg. The main results of the cell stack and system design as well as performance data are presented. Furthermore simulation models and the model based development of the ''Smart Redox flow Control'' are described. For the optimized integration of the storage unit in the energy system a communication interface for exchanging data with the supervisory energy management system is introduced. On this basis a SOC forecast according to a given demand profile can be determined. (orig.)

Mitochondrial Energy and Redox Signaling in Plants

Science.gov (United States)

Schwarzländer, Markus

2013-01-01

Abstract Significance: For a plant to grow and develop, energy and appropriate building blocks are a fundamental requirement. Mitochondrial respiration is a vital source for both. The delicate redox processes that make up respiration are affected by the plant's changing environment. Therefore, mitochondrial regulation is critically important to maintain cellular homeostasis. This involves sensing signals from changes in mitochondrial physiology, transducing this information, and mounting tailored responses, by either adjusting mitochondrial and cellular functions directly or reprogramming gene expression. Recent Advances: Retrograde (RTG) signaling, by which mitochondrial signals control nuclear gene expression, has been a field of very active research in recent years. Nevertheless, no mitochondrial RTG-signaling pathway is yet understood in plants. This review summarizes recent advances toward elucidating redox processes and other bioenergetic factors as a part of RTG signaling of plant mitochondria. Critical Issues: Novel insights into mitochondrial physiology and redox-regulation provide a framework of upstream signaling. On the other end, downstream responses to modified mitochondrial function have become available, including transcriptomic data and mitochondrial phenotypes, revealing processes in the plant that are under mitochondrial control. Future Directions: Drawing parallels to chloroplast signaling and mitochondrial signaling in animal systems allows to bridge gaps in the current understanding and to deduce promising directions for future research. It is proposed that targeted usage of new technical approaches, such as quantitative in vivo imaging, will provide novel leverage to the dissection of plant mitochondrial signaling. Antioxid. Redox Signal. 18, 2122–2144. PMID:23234467

Compromised redox homeostasis, altered nitroso-redox balance, and therapeutic possibilities in atrial fibrillation.

Science.gov (United States)

Simon, Jillian N; Ziberna, Klemen; Casadei, Barbara

2016-04-01

Although the initiation, development, and maintenance of atrial fibrillation (AF) have been linked to alterations in myocyte redox state, the field lacks a complete understanding of the impact these changes may have on cellular signalling, atrial electrophysiology, and disease progression. Recent studies demonstrate spatiotemporal changes in reactive oxygen species production shortly after the induction of AF in animal models with an uncoupling of nitric oxide synthase activity ensuing in the presence of long-standing persistent AF, ultimately leading to a major shift in nitroso-redox balance. However, it remains unclear which radical or non-radical species are primarily involved in the underlying mechanisms of AF or which proteins are targeted for redox modification. In most instances, only free radical oxygen species have been assessed; yet evidence from the redox signalling field suggests that non-radical species are more likely to regulate cellular processes. A wider appreciation for the distinction of these species and how both species may be involved in the development and maintenance of AF could impact treatment strategies. In this review, we summarize how redox second-messenger systems are regulated and discuss the recent evidence for alterations in redox regulation in the atrial myocardium in the presence of AF, while identifying some critical missing links. We also examine studies looking at antioxidants for the prevention and treatment of AF and propose alternative redox targets that may serve as superior therapeutic options for the treatment of AF. © The Author 2016. Published by Oxford University Press on behalf of the European Society of Cardiology.

Redox and Ionic Homeostasis Regulations against Oxidative, Salinity and Drought Stress in Wheat (A Systems Biology Approach

Directory of Open Access Journals (Sweden)

Zahid Hussain Shah

2017-10-01

Full Text Available Systems biology and omics has provided a comprehensive understanding about the dynamics of the genome, metabolome, transcriptome, and proteome under stress. In wheat, abiotic stresses trigger specific networks of pathways involved in redox and ionic homeostasis as well as osmotic balance. These networks are considerably more complicated than those in model plants, and therefore, counter models are proposed by unifying the approaches of omics and stress systems biology. Furthermore, crosstalk among these pathways is monitored by the regulation and streaming of transcripts and genes. In this review, we discuss systems biology and omics as a promising tool to study responses to oxidative, salinity, and drought stress in wheat.

Engineering redox balance through cofactor systems.

Science.gov (United States)

Chen, Xiulai; Li, Shubo; Liu, Liming

2014-06-01

Redox balance plays an important role in the production of enzymes, pharmaceuticals, and chemicals. To meet the demands of industrial production, it is desirable that microbes maintain a maximal carbon flux towards target metabolites with no fluctuations in redox. This requires functional cofactor systems that support dynamic homeostasis between different redox states or functional stability in a given redox state. Redox balance can be achieved by improving the self-balance of a cofactor system, regulating the substrate balance of a cofactor system, and engineering the synthetic balance of a cofactor system. This review summarizes how cofactor systems can be manipulated to improve redox balance in microbes. Copyright © 2014 Elsevier Ltd. All rights reserved.

Membrane development for vanadium redox flow batteries.

Science.gov (United States)

Schwenzer, Birgit; Zhang, Jianlu; Kim, Soowhan; Li, Liyu; Liu, Jun; Yang, Zhenguo

2011-10-17

Large-scale energy storage has become the main bottleneck for increasing the percentage of renewable energy in our electricity grids. Redox flow batteries are considered to be among the best options for electricity storage in the megawatt range and large demonstration systems have already been installed. Although the full technological potential of these systems has not been reached yet, currently the main problem hindering more widespread commercialization is the high cost of redox flow batteries. Nafion, as the preferred membrane material, is responsible for about 11% of the overall cost of a 1 MW/8 MWh system. Therefore, in recent years two main membrane related research threads have emerged: 1) chemical and physical modification of Nafion membranes to optimize their properties with regard to vanadium redox flow battery (VRFB) application; and 2) replacement of the Nafion membranes with different, less expensive materials. This review summarizes the underlying basic scientific issues associated with membrane use in VRFBs and presents an overview of membrane-related research approaches aimed at improving the efficiency of VRFBs and making the technology cost-competitive. Promising research strategies and materials are identified and suggestions are provided on how materials issues could be overcome.

Rhodium-catalyzed redox-neutral coupling of phenidones with alkynes.

Science.gov (United States)

Fan, Zhoulong; Lu, Heng; Li, Wei; Geng, Kaijun; Zhang, Ao

2017-07-21

A switchable synthesis of N-substituted indole derivatives from phenidones via rhodium-catalyzed redox-neutral C-H activation has been achieved. In this protocol, we firstly disclosed that the reactivity of Rh(iii) catalysis could be enhanced through employing palladium acetate as an additive. Some representative features include external oxidant-free, applicable to terminal alkynes, short reaction time and operational simplicity. The utility of this method is further showcased by the economical synthesis of potent anticancer PARP-1 inhibitors.

Fundamental understanding and practical challenges of anionic redox activity in Li-ion batteries

Science.gov (United States)

Assat, Gaurav; Tarascon, Jean-Marie

2018-05-01

Our increasing dependence on lithium-ion batteries for energy storage calls for continual improvements in the performance of their positive electrodes, which have so far relied solely on cationic redox of transition-metal ions for driving the electrochemical reactions. Great hopes have recently been placed on the emergence of anionic redox—a transformational approach for designing positive electrodes as it leads to a near-doubling of capacity. But questions have been raised about the fundamental origins of anionic redox and whether its full potential can be realized in applications. In this Review, we discuss the underlying science that triggers a reversible and stable anionic redox activity. Furthermore, we highlight its practical limitations and outline possible approaches for improving such materials and designing new ones. We also summarize their chances for market implementation in the face of the competing nickel-based layered cathodes that are prevalent today.

Redox Buffer Strength

Science.gov (United States)

de Levie, Robert

1999-04-01

The proper functioning of enzymes in bodily fluids requires that the pH be maintained within rather narrow limits. The first line of defense against large pH fluctuations in such fluids is the passive control provided by the presence of pH buffers. The ability of pH buffers to stabilize the pH is indicated by the buffer value b introduced in 1922 by van Slyke. It is equally important for many enzymes that the redox potential is kept within a narrow range. In that case, stability of the potential is most readily achieved with a redox buffer. In this communication we define the redox buffer strength by analogy with acid-base buffer strength.

ECONOMIC SECURITY – NEW APPROACHES IN THE CONTEXT OF GLOBALIZATION

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Gabriel ANDRUSEAC

2015-08-01

Full Text Available Nowadays, more than ever, economic relations between states are the ones that define the general character of the relations between them and establish economic security as a concept which cannot be neglected anymore. Globalization, the process that shapes the international environment, undermines the old definition of economic security and forces its redefinition. The article aims to identify and analyse the effects of globalization on economic security and the new approaches it takes in this context.

Flowable Conducting Particle Networks in Redox-Active Electrolytes for Grid Energy Storage

Energy Technology Data Exchange (ETDEWEB)

Hatzell, K. B.; Boota, M.; Kumbur, E. C.; Gogotsi, Y.

2015-01-01

This study reports a new hybrid approach toward achieving high volumetric energy and power densities in an electrochemical flow capacitor for grid energy storage. The electrochemical flow capacitor suffers from high self-discharge and low energy density because charge storage is limited to the available surface area (electric double layer charge storage). Here, we examine two carbon materials as conducting particles in a flow battery electrolyte containing the VO2+/VO2+ redox couple. Highly porous activated carbon spheres (CSs) and multi-walled carbon nanotubes (MWCNTs) are investigated as conducting particle networks that facilitate both faradaic and electric double layer charge storage. Charge storage contributions (electric double layer and faradaic) are distinguished for flow-electrodes composed of MWCNTs and activated CSs. A MWCNT flow-electrode based in a redox-active electrolyte containing the VO2+/VO2+ redox couple demonstrates 18% less self-discharge, 10 X more energy density, and 20 X greater power densities (at 20 mV s-1) than one based on a non-redox active electrolyte. Furthermore, a MWCNT redox-active flow electrode demonstrates 80% capacitance retention, and >95% coulombic efficiency over 100 cycles, indicating the feasibility of utilizing conducting networks with redox chemistries for grid energy storage.

Chemical Principles Revisited. Redox Reactions and the Electropotential Axis.

Science.gov (United States)

Vella, Alfred J.

1990-01-01

This paper suggests a nontraditional pedagogic approach to the subject of redox reactions and electrode potentials suitable for freshman chemistry. Presented is a method for the representation of galvanic cells without the introduction of the symbology and notation of conventional cell diagrams. (CW)

Redox Flow Batteries, a Review

Energy Technology Data Exchange (ETDEWEB)

Knoxville, U. Tennessee; U. Texas Austin; U, McGill; Weber, Adam Z.; Mench, Matthew M.; Meyers, Jeremy P.; Ross, Philip N.; Gostick, Jeffrey T.; Liu, Qinghua

2011-07-15

Redox flow batteries are enjoying a renaissance due to their ability to store large amounts of electrical energy relatively cheaply and efficiently. In this review, we examine the components of redox flow batteries with a focus on understanding the underlying physical processes. The various transport and kinetic phenomena are discussed along with the most common redox couples.

The Economic Security of Bank: Theoretical Basis and Systemic Approach

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Gavlovska Nataliia I.

2017-07-01

Full Text Available The article analyzes the existing approaches to interpreting the category of «economic security of bank». A author’s own definition of the concept of «economic security of bank» has been proposed, which should be understood as condition of protecting the vital interests of bank, achieved by harmonizing relationships with the entities of external influence and optimizing the internal system processes, thus enabling efficient function as well as development by means of an adaptation mechanism. A number of approaches to understanding the substance of the above concept has been allocated and their main characteristics have been provided. The need to study the specifics of interaction of banking institutions with the external environment in the context of interaction between the State agents and market actors has been underlined. Features of formation of the term of «system» have been defined, three main groups of approaches to interpretation of the term have been provided. A author’s own definition of the concept of «economic security system of bank» has been proposed. A concrete definition of principles for building an economic security system of bank has been provided.

TWO IDEAS OF THE REDOX REACTION: MISCONCEPTIONS AND ...

African Journals Online (AJOL)

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1), or with the reaction of iron and a copper sulfate solution (see Fig. 2). ... Since neither the young people know the historical approach to the explanation of ... everyday life the concept of electron transfer in redox reactions, a good instruction on ..... Improving teaching and learning through chemistry education research: A.

An object-oriented approach to energy-economic modeling

Energy Technology Data Exchange (ETDEWEB)

Wise, M.A.; Fox, J.A.; Sands, R.D.

1993-12-01

In this paper, the authors discuss the experiences in creating an object-oriented economic model of the U.S. energy and agriculture markets. After a discussion of some central concepts, they provide an overview of the model, focusing on the methodology of designing an object-oriented class hierarchy specification based on standard microeconomic production functions. The evolution of the model from the class definition stage to programming it in C++, a standard object-oriented programming language, will be detailed. The authors then discuss the main differences between writing the object-oriented program versus a procedure-oriented program of the same model. Finally, they conclude with a discussion of the advantages and limitations of the object-oriented approach based on the experience in building energy-economic models with procedure-oriented approaches and languages.

Redox electrode materials for supercapatteries

OpenAIRE

Yu, Linpo; Chen, George Z.

2016-01-01

Redox electrode materials, including transition metal oxides and electronically conducting polymers, are capable of faradaic charge transfer reactions, and play important roles in most electrochemical energy storage devices, such as supercapacitor, battery and supercapattery. Batteries are often based on redox materials with low power capability and safety concerns in some cases. Supercapacitors, particularly those based on redox inactive materials, e.g. activated carbon, can offer high power...

A CDT-Based Heuristic Zone Design Approach for Economic Census Investigators

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Changixu Cheng

2015-01-01

Full Text Available This paper addresses a special zone design problem for economic census investigators that is motivated by a real-world application. This paper presented a heuristic multikernel growth approach via Constrained Delaunay Triangulation (CDT. This approach not only solved the barriers problem but also dealt with the polygon data in zoning procedure. In addition, it uses a new heuristic method to speed up the zoning process greatly on the premise of the required quality of zoning. At last, two special instances for economic census were performed, highlighting the performance of this approach.

Economic Systems: A Modular Approach. Cultural Anthropology.

Science.gov (United States)

Kassebaum, Peter

Designed for use as supplementary instructional material in a cultural anthropology course, this learning module uses a systems approach to allow students to see the connections and similarities which most cultural groups share on the basis of the type of economic organization that they exhibit. The module begins with a general discussion of…

The economic importance of meetings and conferences: A satellite account approach

OpenAIRE

Jones, C; Li, S

2015-01-01

Meetings and conventions (MICE) visitation is often considered an important element of the travel economy, and destinations target such activities to encourage their growth. It has hitherto been difficult to measure the economic significance of such activity at any spatial scale. Latterly, the development and codification of tourism satellite account (TSA) approaches to the economic measurement of tourism offers an opportunity to develop a parallel approach to understanding the MICE economy. ...

Redox reaction studies by nanosecond pulse radiolysis

International Nuclear Information System (INIS)

Moorthy, P.N.

1979-01-01

Free radicals are formed as intermediates in many chemical and biochemical reactions. An important type of reaction which they can undergo is a one electron or redox process. The direction and rate of such electron transfer reactions is governed by the relative redox potentials of the participating species. Because of the generally short lived nature of free radicals, evaluation of their redox potentials poses a number of problems. Two techniques are described for the experimental determination of the redox potentials of short lived species generated by either a nanosecond electron pulse or laser flash. In the first method, redox titration of the short lived species with stable molecules of known redox potential is carried out, employing the technique of fast kinetic spectrophotometry. Conversely, by the same method it is also possible to evaluate the one electron redox potentials of stable molecules by redox titration with free radicals of known redox potential produced as above. In the second method, electrochemical reduction or oxidation of the short lived species at an appropriate electrode (generally a mercury drop) is carried out at different fixed potentials, and the redox potential evaluated from the current-potential curves (polarograms). Full description of the experimental set up and theoretical considerations for interpretation of the raw data are given. The relative merits of the two methods and their practical applicability are discussed. (auth.)

Imaging dynamic redox processes with genetically encoded probes.

Science.gov (United States)

Ezeriņa, Daria; Morgan, Bruce; Dick, Tobias P

2014-08-01

Redox signalling plays an important role in many aspects of physiology, including that of the cardiovascular system. Perturbed redox regulation has been associated with numerous pathological conditions; nevertheless, the causal relationships between redox changes and pathology often remain unclear. Redox signalling involves the production of specific redox species at specific times in specific locations. However, until recently, the study of these processes has been impeded by a lack of appropriate tools and methodologies that afford the necessary redox species specificity and spatiotemporal resolution. Recently developed genetically encoded fluorescent redox probes now allow dynamic real-time measurements, of defined redox species, with subcellular compartment resolution, in intact living cells. Here we discuss the available genetically encoded redox probes in terms of their sensitivity and specificity and highlight where uncertainties or controversies currently exist. Furthermore, we outline major goals for future probe development and describe how progress in imaging methodologies will improve our ability to employ genetically encoded redox probes in a wide range of situations. This article is part of a special issue entitled "Redox Signalling in the Cardiovascular System." Copyright © 2014 Elsevier Ltd. All rights reserved.

Redox responses are preserved across muscle fibres with differential susceptibility to aging.

Science.gov (United States)

Smith, Neil T; Soriano-Arroquia, Ana; Goljanek-Whysall, Katarzyna; Jackson, Malcolm J; McDonagh, Brian

2018-04-15

Age-related loss of muscle mass and function is associated with increased frailty and loss of independence. The mechanisms underlying the susceptibility of different muscle types to age-related atrophy are not fully understood. Reactive oxygen species (ROS) are recognised as important signalling molecules in healthy muscle and redox sensitive proteins can respond to intracellular changes in ROS concentrations modifying reactive thiol groups on Cysteine (Cys) residues. Conserved Cys residues tend to occur in functionally important locations and can have a direct impact on protein function through modifications at the active site or determining protein conformation. The aim of this work was to determine age-related changes in the redox proteome of two metabolically distinct murine skeletal muscles, the quadriceps a predominantly glycolytic muscle and the soleus which contains a higher proportion of mitochondria. To examine the effects of aging on the global proteome and the oxidation state of individual redox sensitive Cys residues, we employed a label free proteomics approach including a differential labelling of reduced and reversibly oxidised Cys residues. Our results indicate the proteomic response to aging is dependent on muscle type but redox changes that occur primarily in metabolic and cytoskeletal proteins are generally preserved between metabolically distinct tissues. Skeletal muscle containing fast twitch glycolytic fibres are more susceptible to age related atrophy compared to muscles with higher proportions of oxidative slow twitch fibres. Contracting skeletal muscle generates reactive oxygen species that are required for correct signalling and adaptation to exercise and it is also known that the intracellular redox environment changes with age. To identify potential mechanisms for the distinct response to age, this article combines a global proteomic approach and a differential labelling of reduced and reversibly oxidised Cysteine residues in two

Enhancing Specific Energy and Power in Asymmetric Supercapacitors - A Synergetic Strategy based on the Use of Redox Additive Electrolytes

Science.gov (United States)

Singh, Arvinder; Chandra, Amreesh

2016-01-01

The strategy of using redox additive electrolyte in combination with multiwall carbon nanotubes/metal oxide composites leads to a substantial improvements in the specific energy and power of asymmetric supercapacitors (ASCs). When the pure electrolyte is optimally modified with a redox additive viz., KI, ~105% increase in the specific energy is obtained with good cyclic stability over 3,000 charge-discharge cycles and ~14.7% capacitance fade. This increase is a direct consequence of the iodine/iodide redox pairs that strongly modifies the faradaic and non-faradaic type reactions occurring on the surface of the electrodes. Contrary to what is shown in few earlier reports, it is established that indiscriminate increase in the concentration of redox additives will leads to performance loss. Suitable explanations are given based on theoretical laws. The specific energy or power values being reported in the fabricated ASCs are comparable or higher than those reported in ASCs based on toxic acetonitrile or expensive ionic liquids. The paper shows that the use of redox additive is economically favorable strategy for obtaining cost effective and environmentally friendly ASCs. PMID:27184260

A Membrane‐Free Redox Flow Battery with Two Immiscible Redox Electrolytes

OpenAIRE

Navalpotro, Paula; Palma, Jesus; Anderson, Marc; Marcilla, Rebeca

2017-01-01

Abstract Flexible and scalable energy storage solutions are necessary for mitigating fluctuations of renewable energy sources. The main advantage of redox flow batteries is their ability to decouple power and energy. However, they present some limitations including poor performance, short‐lifetimes, and expensive ion‐selective membranes as well as high price, toxicity, and scarcity of vanadium compounds. We report a membrane‐free battery that relies on the immiscibility of redox electrolytes ...

Modelling efficient innovative work: integration of economic and social psychological approaches

Directory of Open Access Journals (Sweden)

Babanova Yulia

2017-01-01

Full Text Available The article deals with the relevance of integration of economic and social psychological approaches to the solution of enhancing the efficiency of innovation management. The content, features and specifics of the modelling methods within each of approaches are unfolded and options of integration are considered. The economic approach lies in the generation of the integrated matrix concept of management of innovative development of an enterprise in line with the stages of innovative work and the use of the integrated vector method for the evaluation of the innovative enterprise development level. The social psychological approach lies in the development of a system of psychodiagnostic indexes of activity resources within the scope of psychological innovative audit of enterprise management and development of modelling methods for the balance of activity trends. Modelling the activity resources is based on the system of equations accounting for the interaction type of psychodiagnostic indexes. Integration of two approaches includes a methodological level, a level of empirical studies and modelling methods. There are suggested options of integrating the economic and psychological approaches to analyze available material and non-material resources of the enterprises’ innovative work and to forecast an optimal option of development based on the implemented modelling methods.

Flavin-catalyzed redox tailoring reactions in natural product biosynthesis.

Science.gov (United States)

Teufel, Robin

2017-10-15

Natural products are distinct and often highly complex organic molecules that constitute not only an important drug source, but have also pushed the field of organic chemistry by providing intricate targets for total synthesis. How the astonishing structural diversity of natural products is enzymatically generated in biosynthetic pathways remains a challenging research area, which requires detailed and sophisticated approaches to elucidate the underlying catalytic mechanisms. Commonly, the diversification of precursor molecules into distinct natural products relies on the action of pathway-specific tailoring enzymes that catalyze, e.g., acylations, glycosylations, or redox reactions. This review highlights a selection of tailoring enzymes that employ riboflavin (vitamin B2)-derived cofactors (FAD and FMN) to facilitate unusual redox catalysis and steer the formation of complex natural product pharmacophores. Remarkably, several such recently reported flavin-dependent tailoring enzymes expand the classical paradigms of flavin biochemistry leading, e.g., to the discovery of the flavin-N5-oxide - a novel flavin redox state and oxygenating species. Copyright © 2017 Elsevier Inc. All rights reserved.

Regulatory redox state in tree seeds

Directory of Open Access Journals (Sweden)

Ewelina Ratajczak

2017-12-01

Full Text Available Peroxiredoxins (Prx are important regulators of the redox status of tree seeds during maturation and long-term storage. Thioredoxins (Trx are redox transmitters and thereby regulate Prx activity. Current research is focused on the association of Trx with Prx in tree seeds differing in the tolerance to desiccation. The results will allow for better understanding the regulation of the redox status in orthodox, recalcitrant, and intermediate seeds. The findings will also elucidate the role of the redox status during the loss of viability of sensitive seeds during drying and long-term storage.

Tuning of redox regulatory mechanisms, reactive oxygen species and redox homeostasis under salinity stress

Directory of Open Access Journals (Sweden)

Hossain eSazzad

2016-05-01

Full Text Available Soil salinity is a crucial environmental constraint which limits biomass production at many sites on a global scale. Saline growth conditions cause osmotic and ionic imbalances, oxidative stress and perturb metabolism, e.g. the photosynthetic electron flow. The plant ability to tolerate salinity is determined by multiple biochemical and physiological mechanisms protecting cell functions, in particular by regulating proper water relations and maintaining ion homeostasis. Redox homeostasis is a fundamental cell property. Its regulation includes control of reactive oxygen species (ROS generation, sensing deviation from and readjustment of the cellular redox state. All these redox related functions have been recognized as decisive factors in salinity acclimation and adaptation. This review focuses on the core response of plants to overcome the challenges of salinity stress through regulation of ROS generation and detoxification systems and to maintain redox homeostasis. Emphasis is given to the role of NADH oxidase (RBOH, alternative oxidase (AOX, the plastid terminal oxidase (PTOX and the malate valve with the malate dehydrogenase isoforms under salt stress. Overwhelming evidence assigns an essential auxiliary function of ROS and redox homeostasis to salinity acclimation of plants.

An Optimization Approach to the Dynamic Allocation of Economic Capital

NARCIS (Netherlands)

Laeven, R.J.A.; Goovaerts, M.J.

2004-01-01

We propose an optimization approach to allocating economic capital, distinguishing between an allocation or raising principle and a measure for the risk residual. The approach is applied both at the aggregate (conglomerate) level and at the individual (subsidiary) level and yields an integrated

Sustainable Groundwater Management Using Economic Incentive Approach

Science.gov (United States)

Yan, T.; Shih, J.; Sanchirico, J. N.

2006-12-01

Although groundwater accounts for about 20% of the water consumption in the US, recent urban development, land use changes and agricultural activities in many regions (for example, Chesapeake Bay and eastern shore of Maryland) have resulted in deleterious impacts on groundwater quality. These impacts have dramatically increased potential human health and ecological system risks. One example is nitrogen pollution delivered to local waterways from septic systems via groundwater. Conventional approaches for nitrogen removal, such as pumping and treatment (nitrification-denitrification) process, tend to be expensive. On the other hand, economic incentive approaches (such as marketable permits) have the potential to increase the efficiency of environmental policy by reducing compliance costs for regulated entities and individuals and/or achieving otherwise uneconomical pollution reduction. The success of the sulfur dioxide trading market has led to the creation of trading markets for other pollutants, especially at the regional, state, and smaller (e.g. watershed) scales. In this paper, we develop an integrated framework, which includes a groundwater flow and transport model, and a conceptual management model. We apply this framework to a synthetic set up which includes one farm and two development areas in order to investigate the potential of using economic incentive approaches for groundwater quality management. The policy analysis is carried out by setting up the objective of the modeling framework to minimize the total cost of achieving groundwater quality goals at specific observation point using either a transferable development right (TDR) system between development areas and/or using a tax for fertilizer usage in the farm area. The TDR system consists of a planning agency delineating a region into restricted-use (e.g., agriculture, open space) and high intensity zones (e.g., residential, commercial uses). The agency then endows landowners in the restricted area

Zinc and the modulation of redox homeostasis

Science.gov (United States)

Oteiza, Patricia I.

2012-01-01

Zinc, a redox inactive metal, has been long viewed as a component of the antioxidant network, and growing evidence points to its involvement in redox-regulated signaling. These actions are exerted through several mechanisms based on the unique chemical and functional properties of zinc. Overall, zinc contributes to maintain the cell redox balance through different mechanisms including: i) the regulation of oxidant production and metal-induced oxidative damage; ii) the dynamic association of zinc with sulfur in protein cysteine clusters, from which the metal can be released by nitric oxide, peroxides, oxidized glutathione and other thiol oxidant species; iii) zinc-mediated induction of the zinc-binding protein metallothionein, which releases the metal under oxidative conditions and act per se scavenging oxidants; iv) the involvement of zinc in the regulation of glutathione metabolism and of the overall protein thiol redox status; and v) a direct or indirect regulation of redox signaling. Findings of oxidative stress, altered redox signaling, and associated cell/tissue disfunction in cell and animal models of zinc deficiency, stress the relevant role of zinc in the preservation of cell redox homeostasis. However, while the participation of zinc in antioxidant protection, redox sensing, and redox-regulated signaling is accepted, the involved molecules, targets and mechanisms are still partially known and the subject of active research. PMID:22960578

Redox Regulation of Endothelial Cell Fate

Science.gov (United States)

Song, Ping; Zou, Ming-Hui

2014-01-01

Endothelial cells (ECs) are present throughout blood vessels and have variable roles in both physiological and pathological settings. EC fate is altered and regulated by several key factors in physiological or pathological conditions. Reactive nitrogen species and reactive oxygen species derived from NAD(P)H oxidases, mitochondria, or nitric oxide-producing enzymes are not only cytotoxic but also compose a signaling network in the redox system. The formation, actions, key molecular interactions, and physiological and pathological relevance of redox signals in ECs remain unclear. We review the identities, sources, and biological actions of oxidants and reductants produced during EC function or dysfunction. Further, we discuss how ECs shape key redox sensors and examine the biological functions, transcriptional responses, and post-translational modifications evoked by the redox system in ECs. We summarize recent findings regarding the mechanisms by which redox signals regulate the fate of ECs and address the outcome of altered EC fate in health and disease. Future studies will examine if the redox biology of ECs can be targeted in pathophysiological conditions. PMID:24633153

Review on anionic redox for high-capacity lithium- and sodium-ion batteries

International Nuclear Information System (INIS)

Zhao, Chenglong; Lu, Yaxiang; Hu, Yong-Sheng; Chen, Liquan; Wang, Qidi; Li, Baohua

2017-01-01

Rechargeable batteries, especially lithium-ion batteries, are now widely used as power sources for portable electronics and electric vehicles, but material innovations are still needed to satisfy the increasing demand for larger energy density. Recently, lithium- and sodium-rich electrode materials, including the A 2 MO 3 -family layered compounds (A  =  Li, Na; M  =  Mn 4+ , Ru 4+ , etc), have been extensively studied as potential high-capacity electrode materials for a cumulative cationic and anionic redox activity. Negatively charged oxide ions can potentially donate electrons to compensate for the absence of oxidable transition metals as a redox center to further increase the reversible capacity. Understanding and controlling the state-of-the-art anionic redox processes is pivotal for the design of advanced energy materials, highlighted in rechargeable batteries. Hence, experimental and theoretical approaches have been developed to consecutively study the diverting processes, states, and structures involved. In this review, we attempt to present a literature overview and provide insight into the reaction mechanism with respect to the anionic redox processes, proposing some opinions as target oriented. It is hoped that, through this discussion, the search for anionic redox electrode materials with high-capacity rechargeable batteries can be advanced, and practical applications realized as soon as possible. (topical review)

Modern environmental and economic approach of mining industry

Directory of Open Access Journals (Sweden)

Carsten Drebenstedt

2013-03-01

Full Text Available In the article, the need of transition to the rational subsoil use (the alternative mining approach is proved, which unlike general one supposes the increasing of extraction rate of valuable components in the deposit and multiple use of raw materials, the maximizing recycling, the decreasing of land occupation, the increasing of the development period of deposit at some income decrease up to the moderate level, which is enough to provide the attraction for investors. The multicriteriality is considered as the crucial principle of rational subsoil use at taking management decisions, i.e. the considering of ecological, economic and social targets, aimed at receiving moderate profit at proper social and environmental standards. The graphic representation of models of the general mining approach and the alternative one allows to emphasize the specified advantages of transition to rational subsoil resources development and reflect them in design equation. In the paper, three performance strategies providing the implementation of the alternative approach are offered: full-field development, application ecologically and economically effective systems and the development processes, consideration of reclamation and minimization of long term environmental effects of mining

Fasting, but Not Aging, Dramatically Alters the Redox Status of Cysteine Residues on Proteins in Drosophila melanogaster

Directory of Open Access Journals (Sweden)

Katja E. Menger

2015-06-01

Full Text Available Altering the redox state of cysteine residues on protein surfaces is an important response to environmental challenges. Although aging and fasting alter many redox processes, the role of cysteine residues is uncertain. To address this, we used a redox proteomic technique, oxidative isotope-coded affinity tags (OxICAT, to assess cysteine-residue redox changes in Drosophila melanogaster during aging and fasting. This approach enabled us to simultaneously identify and quantify the redox state of several hundred cysteine residues in vivo. Cysteine residues within young flies had a bimodal distribution with peaks at ∼10% and ∼85% reversibly oxidized. Surprisingly, these cysteine residues did not become more oxidized with age. In contrast, 24 hr of fasting dramatically oxidized cysteine residues that were reduced under fed conditions while also reducing cysteine residues that were initially oxidized. We conclude that fasting, but not aging, dramatically alters cysteine-residue redox status in D. melanogaster.

Redox Biology in Neurological Function, Dysfunction, and Aging.

Science.gov (United States)

Franco, Rodrigo; Vargas, Marcelo R

2018-04-23

Reduction oxidation (redox) reactions are central to life and when altered, they can promote disease progression. In the brain, redox homeostasis is recognized to be involved in all aspects of central nervous system (CNS) development, function, aging, and disease. Recent studies have uncovered the diverse nature by which redox reactions and homeostasis contribute to brain physiology, and when dysregulated to pathological consequences. Redox reactions go beyond what is commonly described as oxidative stress and involve redox mechanisms linked to signaling and metabolism. In contrast to the nonspecific nature of oxidative damage, redox signaling involves specific oxidation/reduction reactions that regulate a myriad of neurological processes such as neurotransmission, homeostasis, and degeneration. This Forum is focused on the role of redox metabolism and signaling in the brain. Six review articles from leading scientists in the field that appraise the role of redox metabolism and signaling in different aspects of brain biology including neurodevelopment, neurotransmission, aging, neuroinflammation, neurodegeneration, and neurotoxicity are included. An original research article exemplifying these concepts uncovers a novel link between oxidative modifications, redox signaling, and neurodegeneration. This Forum highlights the recent advances in the field and we hope it encourages future research aimed to understand the mechanisms by which redox metabolism and signaling regulate CNS physiology and pathophysiology. Antioxid. Redox Signal. 00, 000-000.

Exercise redox biochemistry: Conceptual, methodological and technical recommendations

Directory of Open Access Journals (Sweden)

James N. Cobley

2017-08-01

Full Text Available Exercise redox biochemistry is of considerable interest owing to its translational value in health and disease. However, unaddressed conceptual, methodological and technical issues complicate attempts to unravel how exercise alters redox homeostasis in health and disease. Conceptual issues relate to misunderstandings that arise when the chemical heterogeneity of redox biology is disregarded: which often complicates attempts to use redox-active compounds and assess redox signalling. Further, that oxidised macromolecule adduct levels reflect formation and repair is seldom considered. Methodological and technical issues relate to the use of out-dated assays and/or inappropriate sample preparation techniques that confound biochemical redox analysis. After considering each of the aforementioned issues, we outline how each issue can be resolved and provide a unifying set of recommendations. We specifically recommend that investigators: consider chemical heterogeneity, use redox-active compounds judiciously, abandon flawed assays, carefully prepare samples and assay buffers, consider repair/metabolism, use multiple biomarkers to assess oxidative damage and redox signalling. Keywords: Exercise, Oxidative stress, Free radical, Antioxidants, Redox signalling

Identity and individual economic agents: a narrative approach

NARCIS (Netherlands)

Davis, J.B.; White, M.D.; van Staveren, I.

2010-01-01

This paper offers an account of how individuals act as agents when we employ a narrative approach to explaining their personal identities. It applies Korsgaard's idea of a "reflective structure of consciousness" to provide foundations for a richer account of the individual economic agent, and uses

Identity and individual economic agents: a narrative approach

NARCIS (Netherlands)

Davis, J.B.

2009-01-01

This paper offers an account of how individuals act as agents when we employ a narrative approach to explaining their personal identities. It applies Korsgaard's idea of a "reflective structure of consciousness" to provide foundations for a richer account of the individual economic agent, and uses

A Dooyeweerd-based approach to regional economic development

NARCIS (Netherlands)

Aay, H; Van Langevelde, A

2005-01-01

Within regional science there is a need for a general theory of regional economic development, one that evaluates and integrates existing approaches. In this paper, the philosophy of Herman Dooyeweerd is used as a basis for conceptualising the contours of such a theory. Contributions of this

High-energy density nonaqueous all redox flow lithium battery enabled with a polymeric membrane.

Science.gov (United States)

Jia, Chuankun; Pan, Feng; Zhu, Yun Guang; Huang, Qizhao; Lu, Li; Wang, Qing

2015-11-01

Redox flow batteries (RFBs) are considered one of the most promising large-scale energy storage technologies. However, conventional RFBs suffer from low energy density due to the low solubility of the active materials in electrolyte. On the basis of the redox targeting reactions of battery materials, the redox flow lithium battery (RFLB) demonstrated in this report presents a disruptive approach to drastically enhancing the energy density of flow batteries. With LiFePO4 and TiO2 as the cathodic and anodic Li storage materials, respectively, the tank energy density of RFLB could reach ~500 watt-hours per liter (50% porosity), which is 10 times higher than that of a vanadium redox flow battery. The cell exhibits good electrochemical performance under a prolonged cycling test. Our prototype RFLB full cell paves the way toward the development of a new generation of flow batteries for large-scale energy storage.

High–energy density nonaqueous all redox flow lithium battery enabled with a polymeric membrane

Science.gov (United States)

Jia, Chuankun; Pan, Feng; Zhu, Yun Guang; Huang, Qizhao; Lu, Li; Wang, Qing

2015-01-01

Redox flow batteries (RFBs) are considered one of the most promising large-scale energy storage technologies. However, conventional RFBs suffer from low energy density due to the low solubility of the active materials in electrolyte. On the basis of the redox targeting reactions of battery materials, the redox flow lithium battery (RFLB) demonstrated in this report presents a disruptive approach to drastically enhancing the energy density of flow batteries. With LiFePO4 and TiO2 as the cathodic and anodic Li storage materials, respectively, the tank energy density of RFLB could reach ~500 watt-hours per liter (50% porosity), which is 10 times higher than that of a vanadium redox flow battery. The cell exhibits good electrochemical performance under a prolonged cycling test. Our prototype RFLB full cell paves the way toward the development of a new generation of flow batteries for large-scale energy storage. PMID:26702440

Mapping of redox state of mitochondrial cytochromes in live cardiomyocytes using Raman microspectroscopy

DEFF Research Database (Denmark)

Brazhe, Nadezda A; Treiman, Marek; Brazhe, Alexey R

2012-01-01

This paper presents a nonivasive approach to study redox state of reduced cytochromes [Formula: see text], [Formula: see text] and [Formula: see text] of complexes II and III in mitochondria of live cardiomyocytes by means of Raman microspectroscopy. For the first time with the proposed approach ...

Radii of Redox Components from Absolute Redox Potentials Compared with Covalent and Aqueous Ionic Radii

Czech Academy of Sciences Publication Activity Database

Heyrovská, Raji

2010-01-01

Roč. 22, č. 9 (2010), s. 903-907 ISSN 1040-0397 Institutional support: RVO:68081707 Keywords : Electrochemistry * Absolute redox potentials * Radii of redox components Subject RIV: BO - Biophysics Impact factor: 2.721, year: 2010

Elucidation of the Mechanism of Redox Grafting of Diazotated Anthraquinone

DEFF Research Database (Denmark)

Chernyy, Sergey; Bousquet, Antoine; Torbensen, Kristian

2012-01-01

. Scanning electrochemical microscopy was used to study the relationship between the conductivity of thefilm and the charging level of the AQ redox units in the grafted film. For that purpose, approach curves were recorded at a platinum ultramicroelectrode for AQ-containing films on gold and glassy carbon...

Historic, economic and geographic approach to the relations between economic growth and oil prices

International Nuclear Information System (INIS)

Girard, C.

1992-01-01

This paper attempts to analyze the complex relations between energy prices and economic growth. In part 1, the history of the last 30 years is used to analyze the consequences of energy price variations on world economic growth. In part 2, two interpretation schemes are described successively. One has to do with the international oil market, and the other concerns the impact of oil shocks on national economies. In part 3, an approach by type of country leads to conclusions respectively for the industrialized countries, for the developing countries and for the newly industrialized countries. 1 fig

Simultaneous anionic and cationic redox

Science.gov (United States)

Jung, Sung-Kyun; Kang, Kisuk

2017-12-01

It is challenging to unlock anionic redox activity, accompanied by full utilization of available cationic redox process, to boost capacity of battery cathodes. Now, material design by tuning the metal-oxygen interaction is shown to be a promising solution.

Dual redox catalysts for oxygen reduction and evolution reactions: towards a redox flow Li-O2 battery.

Science.gov (United States)

Zhu, Yun Guang; Jia, Chuankun; Yang, Jing; Pan, Feng; Huang, Qizhao; Wang, Qing

2015-06-11

A redox flow lithium-oxygen battery (RFLOB) by using soluble redox catalysts with good performance was demonstrated for large-scale energy storage. The new device enables the reversible formation and decomposition of Li2O2 via redox targeting reactions in a gas diffusion tank, spatially separated from the electrode, which obviates the passivation and pore clogging of the cathode.

Two approaches to meeting the economic challenge for advanced BWR designs

International Nuclear Information System (INIS)

Rao, A.S.; Sawyer, C.D.

1997-01-01

This paper presents the design overview and approach to addressing the aforementioned economic challenges for two Advanced BWR designs. The first plant is the ABWR and the second is the ESBWR. The ABWR relies on proven technology and components and an extensive infrastructure that has been built up over the last 20 years. Because it has proven and standards safety systems it has very limited uncertainty regarding licensing. Finally, it relies on the economies of scale and overall design flexibility to improve the overall economics of power generation. The ESBWR on the other hand has taken an innovative approach to reduce systems and components to simplify the overall plant to improve plant economics. The overall plant design is indeed simpler, but improved economics required reliance on some economies of scale also. This design embodied in the ESBWR, also has minimized the overall development cost by utilizing features and components from the ABWR and SBWR technology programs

Redox-active media for permeable reactive barriers

International Nuclear Information System (INIS)

Sivavec, T.M.; Mackenzie, P.D.; Horney, D.P.; Baghel, S.S.

1997-01-01

In this paper, three classes of redox-active media are described and evaluated in terms of their long-term effectiveness in treating TCE-contaminated groundwater in permeable reactive zones. Zero-valent iron, in the form of recycled cast iron filings, the first class, has received considerable attention as a reactive media and has been used in about a dozen pilot- and full-scale subsurface wall installations. Criteria used in selecting commercial sources of granular iron, will be discussed. Two other classes of redox-active media that have not yet seen wide use in pilot- or full-scale installations will also be described: Fe(II) minerals and bimetallic systems. Fe(II) minerals, including magnetite (Fe 3 O 4 ), and ferrous sulfide (troilite, FeS), are redox-active and afford TCE reduction rates and product distributions that suggest that they react via a reductive mechanism similar to that which operates in the FeO system. Fe(II) species within the passive oxide layer coating the iron metal may act as electron transfer mediators, with FeO serving as the bulk reductant. Bimetallic systems, the third class of redox-active media, are commonly prepared by plating a second metal onto zero-valent iron (e.g., Ni/Fe and Pd/Fe) and have been shown to accelerate solvent degradation rates relative to untreated iron metal. The long-term effectiveness of this approach, however, has not yet been determined in groundwater treatability tests. The results of a Ni-plated iron column study using site groundwater indicate that a change in reduction mechanism (to catalytic dehydrohalogenation/hydrogenation) accounts for the observed rate enhancement. A significant loss in media reactivity was observed over time, attributable to Ni catalyst deactivation or poisoning. Zero-valent iron systems have not shown similar losses in reactivity in long-term laboratory, pilot or field investigations

Heterogeneous redox reactions in groundwater flow systems - Investigation and application of two different coupled codes

Energy Technology Data Exchange (ETDEWEB)

Pfingsten, W.; Carnahan, C.L. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

1995-05-01

Two simulators of reactive chemical transport are applied to a set of problems involving heterogeneous reactions of uranium species. The simulators use similar algorithms to compute the heterogeneous chemical equilibria, but they use different approaches to the computation of solute transport and to the coupling of transport with chemical reactions. One simulator (MCOTAC) sequentially couples calculations of static chemical equilibria to a random-walk simulation of solute advection and dispersion. The other simulator (THCC) directly couples mass action relations for chemical equilibria to finite-difference representations of the solute transport equations. The aim of the comparison was to demonstrate the applicability of the newly developed code MCOTAC to redox problems, and to identify and investigate general differences between the two types of codes within these applications. The chosen heterogeneous redox systems are hypothetically generate systems which provide numerical difficulties within the coupled code calculation. Uranium, an important component of heterogeneous redox systems consisting of uraniferous solids and natural groundwaters, was chosen as a main component in the example redox systems because of practical interest for performance assessment of geological repositories for nuclear wastes. The calculations show reasonable agreement, in general, between the two computational approaches. Specific areas of disagreement arise from numerical difficulties to each approach. Such `benchmarking` can enhance confidence in the overall performance of individual simulators while identifying aspects that may require further investigations and possible modifications. (author) figs., tabs., 7 refs.

Exercise-intensity dependent alterations in plasma redox status do not reflect skeletal muscle redox-sensitive protein signaling.

Science.gov (United States)

Parker, Lewan; Trewin, Adam; Levinger, Itamar; Shaw, Christopher S; Stepto, Nigel K

2018-04-01

Redox homeostasis and redox-sensitive protein signaling play a role in exercise-induced adaptation. The effects of sprint-interval exercise (SIE), high-intensity interval exercise (HIIE) and continuous moderate-intensity exercise (CMIE), on post-exercise plasma redox status are unclear. Furthermore, whether post-exercise plasma redox status reflects skeletal muscle redox-sensitive protein signaling is unknown. In a randomized crossover design, eight healthy adults performed a cycling session of HIIE (5×4min at 75% W max ), SIE (4×30s Wingate's), and CMIE work-matched to HIIE (30min at 50% of W max ). Plasma hydrogen peroxide (H 2 O 2 ), thiobarbituric acid reactive substances (TBARS), superoxide dismutase (SOD) activity, and catalase activity were measured immediately post, 1h, 2h and 3h post-exercise. Plasma redox status biomarkers were correlated with phosphorylation of skeletal muscle p38-MAPK, JNK, NF-κB, and IκBα protein content immediately and 3h post-exercise. Plasma catalase activity was greater with SIE (56.6±3.8Uml -1 ) compared to CMIE (42.7±3.2, pexercise plasma TBARS and SOD activity significantly (pexercise protocol. A significant positive correlation was detected between plasma catalase activity and skeletal muscle p38-MAPK phosphorylation 3h post-exercise (r=0.40, p=0.04). No other correlations were detected (all p>0.05). Low-volume SIE elicited greater post-exercise plasma catalase activity compared to HIIE and CMIE, and greater H 2 O 2 compared to CMIE. Plasma redox status did not, however, adequately reflect skeletal muscle redox-sensitive protein signaling. Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Protein Redox Dynamics During Light-to-Dark Transitions in Cyanobacteria and Impacts Due to Nutrient Limitation

Directory of Open Access Journals (Sweden)

Aaron T Wright

2014-07-01

Full Text Available Protein redox chemistry constitutes a major void in knowledge pertaining to photoautotrophic system regulation and signaling processes. We have employed a chemical biology approach to analyze redox sensitive proteins in live Synechococcus sp. PCC 7002 cells in both light and dark periods, and to understand how cellular redox balance is disrupted during nutrient perturbation. The present work identified 300 putative redox-sensitive proteins that are involved in the generation of reductant, macromolecule synthesis, and carbon flux through central metabolic pathways, and may be involved in cell signaling and response mechanisms. Furthermore, our research suggests that dynamic redox changes in response to specific nutrient limitations, including carbon and nitrogen limitations, contribute to the regulatory changes driven by a shift from light to dark. Taken together, these results contribute to a high-level understanding of post-translational mechanisms regulating flux distributions and suggest potential metabolic engineering targets for redirecting carbon towards biofuel precursors.

Thiol/disulfide redox states in signaling and sensing

Science.gov (United States)

Go, Young-Mi; Jones, Dean P.

2015-01-01

Rapid advances in redox systems biology are creating new opportunities to understand complexities of human disease and contributions of environmental exposures. New understanding of thiol-disulfide systems have occurred during the past decade as a consequence of the discoveries that thiol and disulfide systems are maintained in kinetically controlled steady-states displaced from thermodynamic equilibrium, that a widely distributed family of NADPH oxidases produces oxidants that function in cell signaling, and that a family of peroxiredoxins utilize thioredoxin as a reductant to complement the well-studied glutathione antioxidant system for peroxide elimination and redox regulation. This review focuses on thiol/disulfide redox state in biologic systems and the knowledge base available to support development of integrated redox systems biology models to better understand the function and dysfunction of thiol-disulfide redox systems. In particular, central principles have emerged concerning redox compartmentalization and utility of thiol/disulfide redox measures as indicators of physiologic function. Advances in redox proteomics show that, in addition to functioning in protein active sites and cell signaling, cysteine residues also serve as redox sensors to integrate biologic functions. These advances provide a framework for translation of redox systems biology concepts to practical use in understanding and treating human disease. Biological responses to cadmium, a widespread environmental agent, are used to illustrate the utility of these advances to the understanding of complex pleiotropic toxicities. PMID:23356510

A synthetic redox biofilm made from metalloprotein-prion domain chimera nanowires

Science.gov (United States)

Altamura, Lucie; Horvath, Christophe; Rengaraj, Saravanan; Rongier, Anaëlle; Elouarzaki, Kamal; Gondran, Chantal; Maçon, Anthony L. B.; Vendrely, Charlotte; Bouchiat, Vincent; Fontecave, Marc; Mariolle, Denis; Rannou, Patrice; Le Goff, Alan; Duraffourg, Nicolas; Holzinger, Michael; Forge, Vincent

2017-02-01

Engineering bioelectronic components and set-ups that mimic natural systems is extremely challenging. Here we report the design of a protein-only redox film inspired by the architecture of bacterial electroactive biofilms. The nanowire scaffold is formed using a chimeric protein that results from the attachment of a prion domain to a rubredoxin (Rd) that acts as an electron carrier. The prion domain self-assembles into stable fibres and provides a suitable arrangement of redox metal centres in Rd to permit electron transport. This results in highly organized films, able to transport electrons over several micrometres through a network of bionanowires. We demonstrate that our bionanowires can be used as electron-transfer mediators to build a bioelectrode for the electrocatalytic oxygen reduction by laccase. This approach opens opportunities for the engineering of protein-only electron mediators (with tunable redox potentials and optimized interactions with enzymes) and applications in the field of protein-only bioelectrodes.

Emotions, perceptions and economic behavior. A critical-philosophical approach to the place of Psychology in Economics

Directory of Open Access Journals (Sweden)

Vicente Caballero de la Torre

2012-10-01

Full Text Available This paper presents the origin of the issue of empathy in the History of Ideas and its importance in economics, as well as its revitalization. It concludes that it is not the study of empathy, so fashionable today, but the study of decision making the place where Economics can find the nature of emotions in relation to human behavior. This nature is its power to inhibit behavior. The study of repentance is itself more interesting and helpful for the economy than the study of empathy. Finally, the institutional approach is presented as the best in order to understand the issues related to economic human behavior

Redox homeostasis: The Golden Mean of healthy living

Directory of Open Access Journals (Sweden)

Fulvio Ursini

2016-08-01

Full Text Available The notion that electrophiles serve as messengers in cell signaling is now widely accepted. Nonetheless, major issues restrain acceptance of redox homeostasis and redox signaling as components of maintenance of a normal physiological steady state. The first is that redox signaling requires sudden switching on of oxidant production and bypassing of antioxidant mechanisms rather than a continuous process that, like other signaling mechanisms, can be smoothly turned up or down. The second is the misperception that reactions in redox signaling involve “reactive oxygen species” rather than reaction of specific electrophiles with specific protein thiolates. The third is that hormesis provides protection against oxidants by increasing cellular defense or repair mechanisms rather than by specifically addressing the offset of redox homeostasis. Instead, we propose that both oxidant and antioxidant signaling are main features of redox homeostasis. As the redox shift is rapidly reversed by feedback reactions, homeostasis is maintained by continuous signaling for production and elimination of electrophiles and nucleophiles. Redox homeostasis, which is the maintenance of nucleophilic tone, accounts for a healthy physiological steady state. Electrophiles and nucleophiles are not intrinsically harmful or protective, and redox homeostasis is an essential feature of both the response to challenges and subsequent feedback. While the balance between oxidants and nucleophiles is preserved in redox homeostasis, oxidative stress provokes the establishment of a new radically altered redox steady state. The popular belief that scavenging free radicals by antioxidants has a beneficial effect is wishful thinking. We propose, instead, that continuous feedback preserves nucleophilic tone and that this is supported by redox active nutritional phytochemicals. These nonessential compounds, by activating Nrf2, mimic the effect of endogenously produced electrophiles

Anaerobic microbial redox processes in a landfill leachate contaminated aquifer (Grindsted, Denmark)

Science.gov (United States)

Ludvigsen, L.; Albrechtsen, H.-J.; Heron, G.; Bjerg, P. L.; Christensen, T. H.

1998-10-01

The distribution of anaerobic microbial redox processes was investigated along a 305 m long transect of a shallow landfill-leachate polluted aquifer. By unamended bioassays containing sediment and groundwater, 37 samples were investigated with respect to methane production, sulfate, iron, and manganese reduction, and denitrification. Methane production was restricted to the most reduced part of the plume with rates of 0.003-0.055 nmol CH 4/g dry weight/day. Sulfate reduction was observed at rates of maximum 1.8 nmol SO 42-/g dry weight/day along with methane production in the plume, but sulfate reduction was also observed further downgradient of the landfill. Iron reduction at rates of 5-19 nmol Fe(II)/g dry weight/day was observed in only a few samples, but this may be related to a high detection limit for the iron reducing bioassay. Manganese reduction at rates of maximum 2.4 nmol Mn(II)/g dry weight/day and denitrification at rates of 0.2-37 nmol N 2O-N/g dry weight/day were observed in the less reduced part of the plume. All the redox processes were microbial processes. In many cases, several redox processes took place simultaneously, but in all samples one process dominated accounting for more than 70% of the equivalent carbon conversion. The bioassays showed that the redox zones in the plume identified from the groundwater composition (e.g. as methanogenic and sulfate reducing) locally hosted also other redox processes (e.g. iron reduction). This may have implications for the potential of the redox zone to degrade trace amounts of organic chemicals and suggests that unamended bioassays may be an important supplement to other approaches in characterizing the redox processes in an anaerobic plume.

Exercise redox biochemistry: Conceptual, methodological and technical recommendations.

Science.gov (United States)

Cobley, James N; Close, Graeme L; Bailey, Damian M; Davison, Gareth W

2017-08-01

Exercise redox biochemistry is of considerable interest owing to its translational value in health and disease. However, unaddressed conceptual, methodological and technical issues complicate attempts to unravel how exercise alters redox homeostasis in health and disease. Conceptual issues relate to misunderstandings that arise when the chemical heterogeneity of redox biology is disregarded: which often complicates attempts to use redox-active compounds and assess redox signalling. Further, that oxidised macromolecule adduct levels reflect formation and repair is seldom considered. Methodological and technical issues relate to the use of out-dated assays and/or inappropriate sample preparation techniques that confound biochemical redox analysis. After considering each of the aforementioned issues, we outline how each issue can be resolved and provide a unifying set of recommendations. We specifically recommend that investigators: consider chemical heterogeneity, use redox-active compounds judiciously, abandon flawed assays, carefully prepare samples and assay buffers, consider repair/metabolism, use multiple biomarkers to assess oxidative damage and redox signalling. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

An Approach Toward Replacing Vanadium: A Single Organic Molecule for the Anode and Cathode of an Aqueous Redox-Flow Battery.

Science.gov (United States)

Janoschka, Tobias; Friebe, Christian; Hager, Martin D; Martin, Norbert; Schubert, Ulrich S

2017-04-01

By combining a viologen unit and a 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) radical in one single combi-molecule, an artificial bipolar redox-active material, 1-(4-(((1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)oxy)carbonyl)benzyl)-1'-methyl-[4,4'-bipyridine]-1,1'-diium-chloride ( VIOTEMP ), was created that can serve as both the anode (-0.49 V) and cathode (0.67 V vs. Ag/AgCl) in a water-based redox-flow battery. While it mimics the redox states of flow battery metals like vanadium, the novel aqueous electrolyte does not require strongly acidic media and is best operated at pH 4. The electrochemical properties of VIOTEMP were investigated by using cyclic voltammetry, rotating disc electrode experiments, and spectroelectrochemical methods. A redox-flow battery was built and the suitability of the material for both electrodes was demonstrated through a polarity-inversion experiment. Thus, an organic aqueous electrolyte system being safe in case of cross contamination is presented.

Redox reaction characteristics of riboflavin: a fluorescence spectroelectrochemical analysis and density functional theory calculation.

Science.gov (United States)

Chen, Wei; Chen, Jie-Jie; Lu, Rui; Qian, Chen; Li, Wen-Wei; Yu, Han-Qing

2014-08-01

Riboflavin (RF), the primary redox active component of flavin, is involved in many redox processes in biogeochemical systems. Despite of its wide distribution and important roles in environmental remediation, its redox behaviors and reaction mechanisms in hydrophobic sites remain unclear yet. In this study, spectroelectrochemical analysis and density functional theory (DFT) calculation were integrated to explore the redox behaviors of RF in dimethyl sulfoxide (DMSO), which was used to create a hydrophobic environment. Specifically, cyclic voltafluorometry (CVF) and derivative cyclic voltafluorometry (DCVF) were employed to track the RF concentration changing profiles. It was found that the reduction contained a series of proton-coupled electron transfers dependent of potential driving force. In addition to the electron transfer-chemical reaction-electron transfer process, a disproportionation (DISP1) process was also identified to be involved in the reduction. The redox potential and free energy of each step obtained from the DFT calculations further confirmed the mechanisms proposed based on the experimental results. The combination of experimental and theoretical approaches yields a deep insight into the characteristics of RF in environmental remediation and better understanding about the proton-coupled electron transfer mechanisms. Copyright © 2014 Elsevier B.V. All rights reserved.

A new economic feasibility approach for solar chimney power plant design

International Nuclear Information System (INIS)

Okoye, Chiemeka Onyeka; Solyalı, Oğuz; Taylan, Onur

2016-01-01

Highlights: • A two-stage economic feasibility approach is proposed for the SCPP design. • The optimal size of the SCPP is determined by solving a nonlinear optimization model. • Energy demand and stochasticity of solar radiation and temperature are considered. • The proposed approach is evaluated on locations in Nigeria. • The proposed approach is an effective decision-making tool for the SCPP design. - Abstract: Solar chimney power plants have been accepted as one of the promising technologies for solar energy utilization. The objective of this study is to propose an effective approach to simultaneously determine the optimal dimensions of the solar chimney power plant and the economic feasibility of the proposed plant. For this purpose, a two-stage economic feasibility approach is proposed based on a new nonlinear programming model. In the first stage, the proposed optimization model which determines the optimal plant dimensions that not only minimize the discounted total cost of the system, but also satisfy the energy demand within a specified reliability taking into account the stochasticity of solar radiation and ambient temperature is solved using a commercial optimization solver that guarantees finding the global optimum. In the second stage, the net present value of building the plant is computed by deducting the discounted total cost found in the first stage from the present value of revenues obtained due to selling the electricity generated by the plant. The proposed approach is novel because it determines the optimal dimensions of the plant together with its economic feasibility by taking into account the energy demand and uncertainty in solar radiation and ambient temperature. The proposed approach is applied on a study in Potiskum, Nigeria, which reveals that building a plant with a collector diameter of 1128 m and chimney height of 715 m to Potiskum would be profitable for investors at an annual rate of return of 3% and would provide

Mapping the diatom redox-sensitive proteome provides insight into response to nitrogen stress in the marine environment.

Science.gov (United States)

Rosenwasser, Shilo; Graff van Creveld, Shiri; Schatz, Daniella; Malitsky, Sergey; Tzfadia, Oren; Aharoni, Asaph; Levin, Yishai; Gabashvili, Alexandra; Feldmesser, Ester; Vardi, Assaf

2014-02-18

Diatoms are ubiquitous marine photosynthetic eukaryotes responsible for approximately 20% of global photosynthesis. Little is known about the redox-based mechanisms that mediate diatom sensing and acclimation to environmental stress. Here we used a quantitative mass spectrometry-based approach to elucidate the redox-sensitive signaling network (redoxome) mediating the response of diatoms to oxidative stress. We quantified the degree of oxidation of 3,845 cysteines in the Phaeodactylum tricornutum proteome and identified approximately 300 redox-sensitive proteins. Intriguingly, we found redox-sensitive thiols in numerous enzymes composing the nitrogen assimilation pathway and the recently discovered diatom urea cycle. In agreement with this finding, the flux from nitrate into glutamine and glutamate, measured by the incorporation of (15)N, was strongly inhibited under oxidative stress conditions. Furthermore, by targeting the redox-sensitive GFP sensor to various subcellular localizations, we mapped organelle-specific oxidation patterns in response to variations in nitrogen quota and quality. We propose that redox regulation of nitrogen metabolism allows rapid metabolic plasticity to ensure cellular homeostasis, and thus is essential for the ecological success of diatoms in the marine ecosystem.

Redox active polymers and colloidal particles for flow batteries

Science.gov (United States)

Gavvalapalli, Nagarjuna; Moore, Jeffrey S.; Rodriguez-Lopez, Joaquin; Cheng, Kevin; Shen, Mei; Lichtenstein, Timothy

2018-05-29

The invention provides a redox flow battery comprising a microporous or nanoporous size-exclusion membrane, wherein one cell of the battery contains a redox-active polymer dissolved in the non-aqueous solvent or a redox-active colloidal particle dispersed in the non-aqueous solvent. The redox flow battery provides enhanced ionic conductivity across the electrolyte separator and reduced redox-active species crossover, thereby improving the performance and enabling widespread utilization. Redox active poly(vinylbenzyl ethylviologen) (RAPs) and redox active colloidal particles (RACs) were prepared and were found to be highly effective redox species. Controlled potential bulk electrolysis indicates that 94-99% of the nominal charge on different RAPs is accessible and the electrolysis products are stable upon cycling. The high concentration attainable (>2.0 M) for RAPs in common non-aqueous battery solvents, their electrochemical and chemical reversibility, and their hindered transport across porous separators make them attractive materials for non-aqueous redox flow batteries based on size-selectivity.

Oxygen in human health from life to death – An approach to teaching redox biology and signaling to graduate and medical students

Directory of Open Access Journals (Sweden)

Margaret M. Briehl

2015-08-01

Full Text Available In the absence of oxygen human life is measured in minutes. In the presence of oxygen, normal metabolism generates reactive species (ROS that have the potential to cause cell injury contributing to human aging and disease. Between these extremes, organisms have developed means for sensing oxygen and ROS and regulating their cellular processes in response. Redox signaling contributes to the control of cell proliferation and death. Aberrant redox signaling underlies many human diseases. The attributes acquired by altered redox homeostasis in cancer cells illustrate this particularly well. This teaching review and the accompanying illustrations provide an introduction to redox biology and signaling aimed at instructors of graduate and medical students.

Is the “Ecological and Economic Approach for the Restoration of Collapsed Gullies” in Southern China Really Economic?

Directory of Open Access Journals (Sweden)

Chengchao Wang

2015-07-01

Full Text Available Collapsed gully erosion constantly plagues the sustainability of rural areas in China. To control collapsed gully erosion, an ecological and economic approach, which uses tree plantation to gain economic benefits and control soil erosion, has been widely applied by local governments in Southern China. However, little is known about the economic feasibility of this new method. The objective of this study was to determine the effectiveness and economic benefits of the new method. Based on a case study in Changting County, Southeast China, two farms were selected to represent a timber tree plantation and a fruit tree plantation, respectively. The Annual Capital Capitalization Method and Return on Investment (ROI were selected to conduct cost-benefit analysis. In contrast to previous studies, we found that the new approach was far from economic. The value of the newly-built forestland in Sanzhou Village and Tufang Village is 2738 RMB ha−1 and 5477 RMB ha−1, respectively, which are extremely lower than the costs of ecological restoration. Meanwhile, the annual ROI is −3.60% and −8.90%, respectively, which is negative and also far poorer than the average value of forestry in China. The costs of conservation were substantially over the related economic benefits, and the investors would suffer from greater loss if they invested more in the conservation. Low-cost terraces with timber trees had less economic loss compared with the costly terraces with fruit tree plantation. Moreover, the cost efficiency of the new approaches in soil conservation was also greatly poorer than the conventional method. The costs of conserving one ton soil per year for conventional method, new method for planting timber trees, and planting fruit trees were 164 RMB, 696 RMB, and 11,664 RMB, respectively. Therefore, the new collapsed gully erosion control methods are uneconomic and unsuitable to be widely carried out in China in the near future.

Comparison of methodological approaches to identify economic activity regularities in transition economy

Directory of Open Access Journals (Sweden)

Jitka Poměnková

2011-01-01

Full Text Available Presented paper focuses on consideration and evaluation of methodical approaches to analyze cyclical structure character of economic activity in transition economy. As a starting point, work in time domain is applied, which is followed in frequency domain approach. Both approaches are viewed from methodical as well as application point of view and their advantage and disadvantage are discussed. Consequently, time-frequency domain approach is added and applied on real data. On the basis of obtained results recommendation is formulated. All discussed methodical approaches are also considered from the perspective of capability to evaluate behaving of business cycle in time of global economic crisis before/after year 2008. The empirical part of the paper deals with data of gross domestic product in the Czech Republic in 1996/Q1–2010/Q2.

Redox potentials and kinetics of the Ce 3+/Ce 4+ redox reaction and solubility of cerium sulfates in sulfuric acid solutions

Science.gov (United States)

Paulenova, A.; Creager, S. E.; Navratil, J. D.; Wei, Y.

Experimental work was performed with the aim of evaluating the Ce 4+/Ce 3+ redox couple in sulfuric acid electrolyte for use in redox flow battery (RFB) technology. The solubility of cerium sulfates in 0.1-4.0 M sulfuric acid at 20-60 °C was studied. A synergistic effect of both sulfuric acid concentration and temperature on the solubility of cerous sulfate was observed. The solubility of cerous sulfate significantly decreased with rising concentration of sulfuric acid and rising temperature, while the solubility of ceric sulfate goes through a significant maximum at 40 °C. Redox potentials and the kinetics of the cerous/ceric redox reaction were also studied under the same temperature-concentration conditions. The redox potentials were measured using the combined redox electrode (Pt-Ag/AgCl) in equimolar Ce 4+/Ce 3+ solutions (i.e.[Ce 3+]=[Ce 4+]) in sulfuric acid electrolyte. The Ce 3+/Ce 4+ redox potentials significantly decrease (i.e. shift to more negative values) with rising sulfuric acid concentration; a small maximum is observed at 40 °C. Cyclic voltammetric experiments confirmed slow electrochemical kinetics of the Ce 3+/Ce 4+ redox reaction on carbon glassy electrodes (CGEs) in sulfuric acid solutions. The observed dependencies of solubilities, the redox potentials and the kinetics of Ce 3+/Ce 4+ redox reaction on sulfuric acid concentration are thought to be the result of inequivalent complexation of the two redox species by sulfate anions: the ceric ion is much more strongly bound to sulfate than is the cerous ion. The best temperature-concentration conditions for the RFB electrolytes appear to be 40 °C and 1 M sulfuric acid, where the relatively good solubility of both cerium species, the maximum of redox potentials, and the more or less satisfying stability of CGE s were found. Even so, the relatively low solubility of cerium salts in sulfuric acid media and slow redox kinetics of the Ce 3+/Ce 4+ redox reaction at carbon indicate that the Ce 3+/Ce

Polyoxometalate active charge-transfer material for mediated redox flow battery

Energy Technology Data Exchange (ETDEWEB)

Anderson, Travis Mark; Hudak, Nicholas; Staiger, Chad; Pratt, Harry

2017-01-17

Redox flow batteries including a half-cell electrode chamber coupled to a current collecting electrode are disclosed herein. In a general embodiment, a separator is coupled to the half-cell electrode chamber. The half-cell electrode chamber comprises a first redox-active mediator and a second redox-active mediator. The first redox-active mediator and the second redox-active mediator are circulated through the half-cell electrode chamber into an external container. The container includes an active charge-transfer material. The active charge-transfer material has a redox potential between a redox potential of the first redox-active mediator and a redox potential of the second redox-active mediator. The active charge-transfer material is a polyoxometalate or derivative thereof. The redox flow battery may be particularly useful in energy storage solutions for renewable energy sources and for providing sustained power to an electrical grid.

Multiple redox states of multiheme cytochromes may enable bacterial response to changing redox environments

Science.gov (United States)

Arbour, T.; Wrighton, K. C.; Mullin, S. W.; Castelle, C.; Luef, B.; Gilbert, B.; Banfield, J. F.

2013-12-01

Multiheme c-type cytochromes (MHCs) are key components in electron-transport pathways that enable some microorganisms to transfer electron byproducts of metabolism to a variety of minerals. As a response to changes in mineral redox potential, microbial communities may shift their membership, or individual organisms may adjust protein expression. Alternatively, the ability to respond may be conferred by the innate characteristics of certain electron-transport-chain components. Here, we used potentiostat-controlled microbial fuel cells (MFCs) to measure the timescale of response to imposed changes in redox conditions, thus placing constraints on the importance of these different mechanisms. In the experiments, a solid electrode acts as an electron-accepting mineral whose redox potential can be precisely controlled. We inoculated duplicate MFCs with a sediment/groundwater mixture from an aquifer at Rifle, Colorado, supplied acetate as an electron donor, and obtained stable, mixed-species biofilms dominated by Geobacter and a novel Geobacter-related family. We poised the anode at potentials spanning the range of natural Fe(III)-reduction, then performed cyclic voltammetry (CV) to characterize the overall biofilm redox signature. The apparent biofilm midpoint potential shifted directly with anode set potential when the latter was changed within the range from about -250 to -50 mV vs. SHE. Following a jump in set potential by 200 mV, the CV-midpoint shift by ~100 mV over a timescale of ~30 minutes to a few hours, depending on the direction of the potential change. The extracellular electron transfer molecules, whose overall CV signature is very similar to those of purified MHCs, appear to span a broad redox range (~200 mV), supporting the hypothesis that MHCs confer substantial redox flexibility. This flexibility may be a principle reason for the abundance of MHCs expressed by microorganisms capable of extracellular electron transfer to minerals.

Pyridine nucleotides in regulation of cell death and survival by redox and non-redox reactions.

Science.gov (United States)

Novak Kujundžić, Renata; Žarković, Neven; Gall Trošelj, Koraljka

2014-01-01

Changes of the level and ratios of pyridine nucleotides determine metabolism- dependent cellular redox status and the activity of poly(ADP-ribose) polymerases (PARPs) and sirtuins, thereby influencing several processes closely related to cell survival and death. Pyridine nucleotides participate in numerous metabolic reactions whereby their net cellular level remains constant, but the ratios of NAD+/NADP+ and NADH/NADPH oscillate according to metabolic changes in response to diverse stress signals. In non-redox reactions, NAD+ is degraded and quickly, afterward, resynthesized in the NAD+ salvage pathway, unless overwhelming activation of PARP-1 consumes NAD+ to the point of no return, when the cell can no longer generate enough ATP to accommodate NAD+ resynthesis. The activity of PARP-1 is mandatory for the onset of cytoprotective autophagy on sublethal stress signals. It has become increasingly clear that redox status, largely influenced by the metabolism-dependent composition of the pyridine nucleotides pool, plays an important role in the synthesis of pro-apoptotic and anti-apoptotic sphingolipids. Awareness of the involvement of the prosurvival sphingolipid, sphingosine-1-phosphate, in transition from inflammation to malignant transformation has recently emerged. Here, the participation of pyridine nucleotides in redox and non-redox reactions, sphingolipid metabolism, and their role in cell fate decisions is reviewed.

Glutathione redox potential in the mitochondrial intermembrane space is linked to the cytosol and impacts the Mia40 redox state

Science.gov (United States)

Kojer, Kerstin; Bien, Melanie; Gangel, Heike; Morgan, Bruce; Dick, Tobias P; Riemer, Jan

2012-01-01

Glutathione is an important mediator and regulator of cellular redox processes. Detailed knowledge of local glutathione redox potential (EGSH) dynamics is critical to understand the network of redox processes and their influence on cellular function. Using dynamic oxidant recovery assays together with EGSH-specific fluorescent reporters, we investigate the glutathione pools of the cytosol, mitochondrial matrix and intermembrane space (IMS). We demonstrate that the glutathione pools of IMS and cytosol are dynamically interconnected via porins. In contrast, no appreciable communication was observed between the glutathione pools of the IMS and matrix. By modulating redox pathways in the cytosol and IMS, we find that the cytosolic glutathione reductase system is the major determinant of EGSH in the IMS, thus explaining a steady-state EGSH in the IMS which is similar to the cytosol. Moreover, we show that the local EGSH contributes to the partially reduced redox state of the IMS oxidoreductase Mia40 in vivo. Taken together, we provide a comprehensive mechanistic picture of the IMS redox milieu and define the redox influences on Mia40 in living cells. PMID:22705944

Approaches to defining «financial potential» concept as of economic analysis object

Directory of Open Access Journals (Sweden)

O.M. Dzyubenkо

2017-12-01

Full Text Available The research analyzes the works of scientists who studied the issues of financial potential as an economic category. Due to analyzing the approaches of the scientists to the concept of "financial potential" the author identifies six approaches to the interpretation of its essence, they are: the totality of the enterprise financial resources, the sources of the enterprise economic activity financing, the enterprise economic activity development, the enterprise financial indicators, the system of enterprise financial management, the enterprise efficiency characteristics. It is established that the financial potential is the multifaceted category that characterizes the financial and economic activity of enterprises. The author's definition of the financial potential in the context of its place in the objects of economic analysis is proposed. It is established that the financial potential is the object of the enterprise economic activity management and is the subject to analytical assessments for establishing its state and directions of development.

Redox-flow battery of actinide complexes

International Nuclear Information System (INIS)

Yamamura, Tomoo; Shiokawa, Yoshinobu

2006-01-01

Np battery and U battery were developed. We suggested that Np redox-flow battery should be (-)|Np 3+ ,Np 4+ ||NpO 2 + ,NpO 2 2+ |(+), and U battery (-)|[U III T 2 ] - ,[U IV T 2 ] 0 ||[U V O 2 T] - ,[U VI O 2 T] 0 |(+). The electromotive force at 50 % charge of Np and U battery is 1.10 V and 1.04 V, respectively. The energy efficiency of 70 mA/cm 2 of Np and U battery shows 99 % and 98 %, respectively. V redox-flow battery, electrode reactions of An battery, Np battery, U battery and future of U battery are described. The concept of V redox-flow battery, comparison of energy efficiency of Np, U and V battery, oxidation state and ionic species of 3d transition metals and main An, Purbe diagram of Np and U aqueous solution, shift of redox potential of β-diketones by pKa, and specifications of three redox-flow batteries are reported. (S.Y.)

Redox kinetics and mechanism in silicate melts

International Nuclear Information System (INIS)

Cochain, B.

2009-12-01

This work contributes to better understand iron redox reactions and mechanisms in silicate melts. It was conducted on compositions in both Na 2 O-B 2 O 3 -SiO 2 -FeO and Na 2 O-Al 2 O 3 -SiO 2 -FeO systems. The influence of boron-sodium and aluminum-sodium substitutions and iron content on properties and structure of glasses and on the iron redox kinetics has been studied by Raman, Moessbauer and XANES spectroscopies at the B and Fe K-edges. In borosilicate glasses, an increase in iron content or in the Fe 3+ /ΣFe redox state implies a structural rearrangement of the BO 4 species in the glass network whereas the BO 3 and BO 4 relative proportions remain nearly constant. In all studied glasses and melts, Fe 3+ is a network former in tetrahedral coordination, unless for aluminosilicates of ratio Al/Na≥1 where Fe 3+ is a network modifier in five-fold coordination. Near Tg, diffusion of network modifying cations controls the iron redox kinetics along with a flux of electron holes. At liquidus temperatures, oxygen diffusion is considered to be the mechanism that governs redox reactions. This study shows the role played by the silicate network polymerization on the redox kinetics. In borosilicate melts, iron redox kinetics depends on the boron speciation between BO 3 and BO 4 that depends itself on the sodium content. Furthermore, an increase in the network-former/network-modifier ratio implies a decrease in oxygen diffusion that results in a slowing down of the redox kinetics. The obtained results allow a description of the iron redox kinetics for more complex compositions as natural lavas or nuclear waste model glasses. (author)

Redox homeostasis: The Golden Mean of healthy living.

Science.gov (United States)

Ursini, Fulvio; Maiorino, Matilde; Forman, Henry Jay

2016-08-01

The notion that electrophiles serve as messengers in cell signaling is now widely accepted. Nonetheless, major issues restrain acceptance of redox homeostasis and redox signaling as components of maintenance of a normal physiological steady state. The first is that redox signaling requires sudden switching on of oxidant production and bypassing of antioxidant mechanisms rather than a continuous process that, like other signaling mechanisms, can be smoothly turned up or down. The second is the misperception that reactions in redox signaling involve "reactive oxygen species" rather than reaction of specific electrophiles with specific protein thiolates. The third is that hormesis provides protection against oxidants by increasing cellular defense or repair mechanisms rather than by specifically addressing the offset of redox homeostasis. Instead, we propose that both oxidant and antioxidant signaling are main features of redox homeostasis. As the redox shift is rapidly reversed by feedback reactions, homeostasis is maintained by continuous signaling for production and elimination of electrophiles and nucleophiles. Redox homeostasis, which is the maintenance of nucleophilic tone, accounts for a healthy physiological steady state. Electrophiles and nucleophiles are not intrinsically harmful or protective, and redox homeostasis is an essential feature of both the response to challenges and subsequent feedback. While the balance between oxidants and nucleophiles is preserved in redox homeostasis, oxidative stress provokes the establishment of a new radically altered redox steady state. The popular belief that scavenging free radicals by antioxidants has a beneficial effect is wishful thinking. We propose, instead, that continuous feedback preserves nucleophilic tone and that this is supported by redox active nutritional phytochemicals. These nonessential compounds, by activating Nrf2, mimic the effect of endogenously produced electrophiles (parahormesis). In summary

A new approach towards the enhancement of northeast Asian economic cooperation

Directory of Open Access Journals (Sweden)

Chang-Jae Lee

1999-09-01

Full Text Available This study proposes the formation of the Northeast Asian Economic Cooperation Council (NAECC to discuss comprehensive economic cooperation and major economic issues between Korea, Japan and China. In order to meet the challenge of risign regionalism and to prevent another Asian economic crisis, it is imperative for the central governments of the region to involve themselves more actively in Northeast Asian Economic Cooperation. Given the diversity of Northeast Asian countries, it seems to be more realistic to vegin with the central governments of the three major countries in terms of economic size. However, even amongst these three countries, the prospects for reaching a regional trade agreement such as the North American Free Trade Agreement (NAFTA, let alone a more advanced economic integration type like the EU, are quite dim in the foreseeable future. Thus, Korea, Japan and China must try to get as many benefits of economic integration as possible through a non-traditional approach.

A molecular theory of chemically modified electrodes with self-assembled redox polyelectrolye thin films: Reversible cyclic voltammetry

Energy Technology Data Exchange (ETDEWEB)

Tagliazucchi, Mario; Calvo, Ernesto J. [INQUIMAE, DQIAyQF Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, 1428 Buenos Aires (Argentina); Szleifer, Igal [Department of Biomedical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States)

2008-10-01

A molecular theory of chemically modified electrodes is applied to study redox polyelectroyte modified electrodes. The molecular approach explicitly includes the size, shape, charge distribution, and conformations of all of the molecular species in the system as well as the chemical equilibria (redox and acid-base) and intermolecular interactions. An osmium pyridine-bipyridine complex covalently bound to poly(allyl-amine) backbone (PAH-Os) adsorbed onto mercapto-propane sulfonate (MPS) thiolated gold electrode is described. The potential and electrolyte composition dependent redox and nonredox capacitance can be calculated with the molecular theory in very good agreement with voltammetric experiments under reversible conditions without the use of freely adjustable parameter. Unlike existing phenomenological models the theory links the electrochemical behavior with the structure of the polymer layer. The theory predicts a highly inhomogeneous distribution of acid-base and redox states that strongly couples with the spatial arrangement of the molecular species in the nanometric redox film. (author)

The personnel economics approach to public workforce research.

Science.gov (United States)

Gibbs, Michael

2009-11-01

This article argues that the relatively new field of personnel economics (PE) holds strong potential as a tool for studying public sector workforces. This subfield of labor economics is based on a strong foundation of microeconomics, which provides a robust theoretical foundation for studying workforce and organizational design issues. PE has evolved on this foundation to a strong practical emphasis, with theoretical insights designed for practical use and with strong focus on empirical research. The field is also characterized by creative data entrepreneurship. The types of datasets that personnel economists use are described. If similar datasets can be obtained for public sector workforces, PE should be a very useful approach for studying them.

Unleashing the Power and Energy of LiFePO4-Based Redox Flow Lithium Battery with a Bifunctional Redox Mediator.

Science.gov (United States)

Zhu, Yun Guang; Du, Yonghua; Jia, Chuankun; Zhou, Mingyue; Fan, Li; Wang, Xingzhu; Wang, Qing

2017-05-10

Redox flow batteries, despite great operation flexibility and scalability for large-scale energy storage, suffer from low energy density and relatively high cost as compared to the state-of-the-art Li-ion batteries. Here we report a redox flow lithium battery, which operates via the redox targeting reactions of LiFePO 4 with a bifunctional redox mediator, 2,3,5,6-tetramethyl-p-phenylenediamine, and presents superb energy density as the Li-ion battery and system flexibility as the redox flow battery. The battery has achieved a tank energy density as high as 1023 Wh/L, power density of 61 mW/cm 2 , and voltage efficiency of 91%. Operando X-ray absorption near-edge structure measurements were conducted to monitor the evolution of LiFePO 4 , which provides insightful information on the redox targeting process, critical to the device operation and optimization.

Economic evaluation of I and C modernization approach in NPPs

International Nuclear Information System (INIS)

Kang, Hyeon Tae; Sung, Chan Ho; Lee, Jae Ki

2009-01-01

Utilities have recently been debating the respective pros and cons of implementation of a multi-phase modernization during several normal outages versus a single major modernization implementation during a prolonged outage. We have studied these approaches and have been developing the basic design of NPPs I and C modernization since early 2008. As part of this study, analyses of the NPPs I and C systems were conducted and the need for upgrading the systems was raised. One of the primary concerns regarding the system modernization is a cost-benefit implementation, which will influence the modernization approach. From this viewpoint, the I and C modernization must consider economic factors such as I and C vendor cost, architecture engineering cost, installation cost, utility cost, and other transition costs such as training and procedure development. This paper presents a comparison study of economical aspects including cost evaluation between the aforementioned modernization implementations and suggests a solution for the I and C modernization approach. (author)

Redox properties of iron-bearing clays and MX-80 bentonite – Electrochemical and spectroscopic characterization

International Nuclear Information System (INIS)

Hofstetter, Th. B.; Sosedova, Y.; Gorski, C.; Voegelin, A.; Sander, M.

2014-03-01

The characterization of the redox properties of Fe-bearing minerals in the presence and absence of dissolved Fe"2"+ is of major relevance for the assessment of redox reactions in natural and engineered environments such as radioactive waste repositories. In this study, we developed an electrochemical approach based on the use of soluble organic electron transfer mediators, which enabled us to quantify the redox properties of Fe-bearing clay minerals, MX- 80 bentonite and combinations of clay minerals, Fe oxides and dissolved Fe"2"+. Using mediated electrochemical oxidation and reduction, we quantified the electron accepting and donating capacities of ferrous smectite SWa-1, Wyoming montmorillonite SWy-2 and MX-80 bentonite at pH 7.5. All structural Fe in clay minerals was redox-active in contrast to that present in other, not further defined phases of MX-80. The materials investigated were redoxactive over a very wide range of Eh-values, that is the Fe"2"+/Fe_t_o_t_a_l ratio of the minerals changed from 0 to 100 % between +600 and -600 mV (vs. SHE). Redox properties were highly path-dependent due to structural changes of the minerals as revealed from the study of native and redox-cycled clay minerals after repeated reduction and re-oxidation cycles. Irreversible alteration of the mineral structure, however, was less obvious for materials with lower total Fe content such as MX-80 bentonite and SWy-2. Systems containing native montmorillonites (SWy-2 or MX-80), goethite and dissolved Fe"2"+ were also able to buffer the reduction potential E_H between 0 and -300 mV. Regardless of their Fe oxidation state, Fe-bearing minerals are redox-active over a wide potential range and therefore very relevant as redox buffers determining the fate of redox-active radionuclides and metals in waste repositories. (authors)

Redox properties of iron-bearing clays and MX-80 bentonite – Electrochemical and spectroscopic characterization

Energy Technology Data Exchange (ETDEWEB)

Hofstetter, Th. B.; Sosedova, Y.; Gorski, C.; Voegelin, A.; Sander, M.

2014-03-15

The characterization of the redox properties of Fe-bearing minerals in the presence and absence of dissolved Fe{sup 2+} is of major relevance for the assessment of redox reactions in natural and engineered environments such as radioactive waste repositories. In this study, we developed an electrochemical approach based on the use of soluble organic electron transfer mediators, which enabled us to quantify the redox properties of Fe-bearing clay minerals, MX- 80 bentonite and combinations of clay minerals, Fe oxides and dissolved Fe{sup 2+}. Using mediated electrochemical oxidation and reduction, we quantified the electron accepting and donating capacities of ferrous smectite SWa-1, Wyoming montmorillonite SWy-2 and MX-80 bentonite at pH 7.5. All structural Fe in clay minerals was redox-active in contrast to that present in other, not further defined phases of MX-80. The materials investigated were redoxactive over a very wide range of Eh-values, that is the Fe{sup 2+}/Fe{sub total} ratio of the minerals changed from 0 to 100 % between +600 and -600 mV (vs. SHE). Redox properties were highly path-dependent due to structural changes of the minerals as revealed from the study of native and redox-cycled clay minerals after repeated reduction and re-oxidation cycles. Irreversible alteration of the mineral structure, however, was less obvious for materials with lower total Fe content such as MX-80 bentonite and SWy-2. Systems containing native montmorillonites (SWy-2 or MX-80), goethite and dissolved Fe{sup 2+} were also able to buffer the reduction potential E{sub H} between 0 and -300 mV. Regardless of their Fe oxidation state, Fe-bearing minerals are redox-active over a wide potential range and therefore very relevant as redox buffers determining the fate of redox-active radionuclides and metals in waste repositories. (authors)

Economics of Internet of Things (IoT): An Information Market Approach

OpenAIRE

Niyato, D.; Lu, X.; Wang, P.; Kim, D. I.; Han, Z.

2015-01-01

Internet of things (IoT) has been proposed to be a new paradigm of connecting devices and providing services to various applications, e.g., transportation, energy, smart city, and healthcare. In this paper, we focus on an important issue, i.e., economics of IoT, that can have a great impact to the success of IoT applications. In particular, we adopt and present the information economics approach with its applications in IoT. We first review existing economic models developed for IoT services....

Organic non-aqueous cation-based redox flow batteries

Science.gov (United States)

Jansen, Andrew N.; Vaughey, John T.; Chen, Zonghai; Zhang, Lu; Brushett, Fikile R.

2016-03-29

The present invention provides a non-aqueous redox flow battery comprising a negative electrode immersed in a non-aqueous liquid negative electrolyte, a positive electrode immersed in a non-aqueous liquid positive electrolyte, and a cation-permeable separator (e.g., a porous membrane, film, sheet, or panel) between the negative electrolyte from the positive electrolyte. During charging and discharging, the electrolytes are circulated over their respective electrodes. The electrolytes each comprise an electrolyte salt (e.g., a lithium or sodium salt), a transition-metal free redox reactant, and optionally an electrochemically stable organic solvent. Each redox reactant is selected from an organic compound comprising a conjugated unsaturated moiety, a boron cluster compound, and a combination thereof. The organic redox reactant of the positive electrolyte is selected to have a higher redox potential than the redox reactant of the negative electrolyte.

Energy storage device including a redox-enhanced electrolyte

Science.gov (United States)

Stucky, Galen; Evanko, Brian; Parker, Nicholas; Vonlanthen, David; Auston, David; Boettcher, Shannon; Chun, Sang-Eun; Ji, Xiulei; Wang, Bao; Wang, Xingfeng; Chandrabose, Raghu Subash

2017-08-08

An electrical double layer capacitor (EDLC) energy storage device is provided that includes at least two electrodes and a redox-enhanced electrolyte including two redox couples such that there is a different one of the redox couples for each of the electrodes. When charged, the charge is stored in Faradaic reactions with the at least two redox couples in the electrolyte and in a double-layer capacitance of a porous carbon material that comprises at least one of the electrodes, and a self-discharge of the energy storage device is mitigated by at least one of electrostatic attraction, adsorption, physisorption, and chemisorption of a redox couple onto the porous carbon material.

A novel strategy for global analysis of the dynamic thiol redox proteome.

Science.gov (United States)

Martínez-Acedo, Pablo; Núñez, Estefanía; Gómez, Francisco J Sánchez; Moreno, Margoth; Ramos, Elena; Izquierdo-Álvarez, Alicia; Miró-Casas, Elisabet; Mesa, Raquel; Rodriguez, Patricia; Martínez-Ruiz, Antonio; Dorado, David Garcia; Lamas, Santiago; Vázquez, Jesús

2012-09-01

Nitroxidative stress in cells occurs mainly through the action of reactive nitrogen and oxygen species (RNOS) on protein thiol groups. Reactive nitrogen and oxygen species-mediated protein modifications are associated with pathophysiological states, but can also convey physiological signals. Identification of Cys residues that are modified by oxidative stimuli still poses technical challenges and these changes have never been statistically analyzed from a proteome-wide perspective. Here we show that GELSILOX, a method that combines a robust proteomics protocol with a new computational approach that analyzes variance at the peptide level, allows a simultaneous analysis of dynamic alterations in the redox state of Cys sites and of protein abundance. GELSILOX permits the characterization of the major endothelial redox targets of hydrogen peroxide in endothelial cells and reveals that hypoxia induces a significant increase in the status of oxidized thiols. GELSILOX also detected thiols that are redox-modified by ischemia-reperfusion in heart mitochondria and demonstrated that these alterations are abolished in ischemia-preconditioned animals.

The Keynesian Approach of Business Cycle and Economic Crises and its Criticism

Directory of Open Access Journals (Sweden)

Ionela Bălțătescu

2009-10-01

Full Text Available The main purpose of this article is to briefly present the Keynesian explanation of business cycle, economic fluctuation and crises, and also the solutions proposed from Keynesian perspective to the economic problems that characterize the bust phases of the business cycles (unemployment, recessions. In the fourth section of the article some criticisms of the Keynesian theoretical approach of the economic crises are considered and summarized.

Analysis of Increasing Malwares and Cyber Crimes Using Economic Approach

OpenAIRE

Asgher, Umer; Dar, Fahad Moazzam; Hamza, Ali; Paracha, Abdul Moeed

2014-01-01

The economics of an internet crime has newly developed into a field of controlling black money. This economic approach not only provides estimated technique of analyzing internet crimes but also gives details to analyzers of system dependability and divergence. This paper will highlight on the subject of online crime, which has formed its industry since. It all started from amateur hackers who cracked websites and wrote malicious software in pursuit of fun or achieving limited objectives to p...

Redox properties of structural Fe in clay minerals: 3. Relationships between smectite redox and structural properties.

Science.gov (United States)

Gorski, Christopher A; Klüpfel, Laura E; Voegelin, Andreas; Sander, Michael; Hofstetter, Thomas B

2013-01-01

Structural Fe in clay minerals is an important redox-active species in many pristine and contaminated environments as well as in engineered systems. Understanding the extent and kinetics of redox reactions involving Fe-bearing clay minerals has been challenging due to the inability to relate structural Fe(2+)/Fe(total) fractions to fundamental redox properties, such as reduction potentials (EH). Here, we overcame this challenge by using mediated electrochemical reduction (MER) and oxidation (MEO) to characterize the fraction of redox-active structural Fe (Fe(2+)/Fe(total)) in smectites over a wide range of applied EH-values (-0.6 V to +0.6 V). We examined Fe(2+)/Fe(total )- EH relationships of four natural Fe-bearing smectites (SWy-2, SWa-1, NAu-1, NAu-2) in their native, reduced, and reoxidized states and compared our measurements with spectroscopic observations and a suite of mineralogical properties. All smectites exhibited unique Fe(2+)/Fe(total) - EH relationships, were redox active over wide EH ranges, and underwent irreversible electron transfer induced structural changes that were observable with X-ray absorption spectroscopy. Variations among the smectite Fe(2+)/Fe(total) - EH relationships correlated well with both bulk and molecular-scale properties, including Fe(total) content, layer charge, and quadrupole splitting values, suggesting that multiple structural parameters determined the redox properties of smectites. The Fe(2+)/Fe(total) - EH relationships developed for these four commonly studied clay minerals may be applied to future studies interested in relating the extent of structural Fe reduction or oxidation to EH-values.

Redox biology in normal cells and cancer: restoring function of the redox/Fyn/c-Cbl pathway in cancer cells offers new approaches to cancer treatment.

Science.gov (United States)

Noble, Mark; Mayer-Pröschel, Margot; Li, Zaibo; Dong, Tiefei; Cui, Wanchang; Pröschel, Christoph; Ambeskovic, Ibro; Dietrich, Joerg; Han, Ruolan; Yang, Yin Miranda; Folts, Christopher; Stripay, Jennifer; Chen, Hsing-Yu; Stevens, Brett M

2015-02-01

This review discusses a unique discovery path starting with novel findings on redox regulation of precursor cell and signaling pathway function and identification of a new mechanism by which relatively small changes in redox status can control entire signaling networks that regulate self-renewal, differentiation, and survival. The pathway central to this work, the redox/Fyn/c-Cbl (RFC) pathway, converts small increases in oxidative status to pan-activation of the c-Cbl ubiquitin ligase, which controls multiple receptors and other proteins of central importance in precursor cell and cancer cell function. Integration of work on the RFC pathway with attempts to understand how treatment with systemic chemotherapy causes neurological problems led to the discovery that glioblastomas (GBMs) and basal-like breast cancers (BLBCs) inhibit c-Cbl function through altered utilization of the cytoskeletal regulators Cool-1/βpix and Cdc42, respectively. Inhibition of these proteins to restore normal c-Cbl function suppresses cancer cell division, increases sensitivity to chemotherapy, disrupts tumor-initiating cell (TIC) activity in GBMs and BLBCs, controls multiple critical TIC regulators, and also allows targeting of non-TICs. Moreover, these manipulations do not increase chemosensitivity or suppress division of nontransformed cells. Restoration of normal c-Cbl function also allows more effective harnessing of estrogen receptor-α (ERα)-independent activities of tamoxifen to activate the RFC pathway and target ERα-negative cancer cells. Our work thus provides a discovery strategy that reveals mechanisms and therapeutic targets that cannot be deduced by standard genetics analyses, which fail to reveal the metabolic information, isoform shifts, protein activation, protein complexes, and protein degradation critical to our discoveries. Copyright © 2015. Published by Elsevier Inc.

Ediacaran Redox Fluctuations

Science.gov (United States)

Sahoo, S. K.; Jiang, G.; Planavsky, N. J.; Kendall, B.; Owens, J. D.; Anbar, A. D.; Lyons, T. W.

2013-12-01

Evidence for pervasive oxic conditions, and likely even deep ocean oxygenation has been documented at three intervals in the lower (ca. 632 Ma), middle (ca. 580 Ma) and upper (ca. 551 Ma) Ediacaran. The Doushantuo Formation in South China hosts large enrichments of redox-sensitive trace element (e.g., molybdenum, vanadium and uranium) in anoxic shales, which are indicative of a globally oxic ocean-atmosphere system. However, ocean redox conditions between these periods continue to be a topic of debate and remain elusive. We have found evidence for widespread anoxic conditions through much of the Ediacaran in the deep-water Wuhe section in South China. During most of the Ediacaran-early Cambrian in basinal sections is characterized by Fe speciation data and pyrite morphologies that indicate deposition under euxinic conditions with near-crustal enrichments of redox-sensitive element and positive pyrite-sulfur isotope values, which suggest low levels of marine sulfate and widespread euxinia. Our work reinforces an emerging view that the early Earth, including the Ediacaran, underwent numerous rises and falls in surface oxidation state, rather than a unidirectional rise as originally imagined. The Ediacaran ocean thus experienced repetitive expansion and contraction of marine chalcophilic trace-metal levels that may have had fundamental impact on the slow evolution of early animals and ecosystems. Further, this framework forces us to re-examine the relationship between Neoproterozoic oxygenation and metazoan diversification. Varying redox conditions through the Cryogenian and Ediacaran may help explain molecular clock and biomarker evidence for an early appearance and initial diversification of metazoans but with a delay in the appearance of most major metazoan crown groups until close to Ediacaran-Cambrian boundary.

Redox interplay between mitochondria and peroxisomes

Directory of Open Access Journals (Sweden)

Celien eLismont

2015-05-01

Full Text Available Reduction-oxidation or ‘redox’ reactions are an integral part of a broad range of cellular processes such as gene expression, energy metabolism, protein import and folding, and autophagy. As many of these processes are intimately linked with cell fate decisions, transient or chronic changes in cellular redox equilibrium are likely to contribute to the initiation and progression of a plethora of human diseases. Since a long time, it is known that mitochondria are major players in redox regulation and signaling. More recently, it has become clear that also peroxisomes have the capacity to impact redox-linked physiological processes. To serve this function, peroxisomes cooperate with other organelles, including mitochondria. This review provides a comprehensive picture of what is currently known about the redox interplay between mitochondria and peroxisomes in mammals. We first outline the pro- and antioxidant systems of both organelles and how they may function as redox signaling nodes. Next, we critically review and discuss emerging evidence that peroxisomes and mitochondria share an intricate redox-sensitive relationship and cooperate in cell fate decisions. Key issues include possible physiological roles, messengers, and mechanisms. We also provide examples of how data mining of publicly-available datasets from ‘omics’ technologies can be a powerful means to gain additional insights into potential redox signaling pathways between peroxisomes and mitochondria. Finally, we highlight the need for more studies that seek to clarify the mechanisms of how mitochondria may act as dynamic receivers, integrators, and transmitters of peroxisome-derived mediators of oxidative stress. The outcome of such studies may open up exciting new avenues for the community of researchers working on cellular responses to organelle-derived oxidative stress, a research field in which the role of peroxisomes is currently highly underestimated and an issue of

Multi-physics Model for the Aging Prediction of a Vanadium Redox Flow Battery System

International Nuclear Information System (INIS)

Merei, Ghada; Adler, Sophie; Magnor, Dirk; Sauer, Dirk Uwe

2015-01-01

Highlights: • Present a multi-physics model of vanadium redox-flow battery. • This model is essential for aging prediction. • It is applicable for VRB system of different power and capacity ratings. • Good results comparing with current research in this field. - Abstract: The all-vanadium redox-flow battery is an attractive candidate to compensate the fluctuations of non-dispatchable renewable energy generation. While several models for vanadium redox batteries have been described yet, no model has been published, which is adequate for the aging prediction. Therefore, the present paper presents a multi-physics model which determines all parameters that are essential for an aging prediction. In a following paper, the corresponding aging model of vanadium redox flow battery (VRB) is described. The model combines existing models for the mechanical losses and temperature development with new approaches for the batteries side reactions. The model was implemented in Matlab/Simulink. The modeling results presented in the paper prove to be consistent with the experimental results of other research groups

The Contribution of the Neo-Schumpeterian Approach to the Development of the Economic Theory: Emphasis on the Meso-Economic Level

Directory of Open Access Journals (Sweden)

Radu HERMAN

2011-07-01

Full Text Available This article tries to show that there are alternative approaches to the economic theory, besides the well-known economic schools, Classicism, Neoclassicism and Keynesianism. The neoclassical principles allow a formalization – widely accepted by experts – that provide effective tools for measuring the effects of the economic activity. The economic science pays a special attention to the study of the economic agents’ behaviors, and to the economic results obtained by them through economic activity. Any human science uses principles and works with assumptions, and the neoclassical assumptions have generated efficient tools for quantifying the economic outcomes, and for accounting the economic growth. But these hypothesis, such as the assumption of economic agents’ rationality, allow a very limited understanding of the behaviors of economic agents within the markets. The recent invention of the Nuclear Magnetic Resonance device, allowed the emrgence of a new scientific paradigm, the development of neurosciences. Researchers can observe at a high level of graphic detail various types of activities that occur in the human brain, and some economists have introduced in the study of the economic theory, for example, the assumption that the consumer is driven by emotions when purchasing quantities of goods and services. So, economists may look for additional theories to explain the behavior of the economic agents. An increasingly importance is given to the theoretical contributions built on the work of the economist Joseph Alois Schumpeter, who has an original economic approach based on his own principles. It is proposed to focus the attention on a mesoeconomic vision about the industry, to understand how resources are being allocated and reallocated between companies, and to study the economic processes of evolution, which are influenced by the emergence and dissemination of the innovations. It is supposed that the price is allocating the

Redox self-sufficient whole cell biotransformation for amination of alcohols.

Science.gov (United States)

Klatte, Stephanie; Wendisch, Volker F

2014-10-15

Whole cell biotransformation is an upcoming tool to replace common chemical routes for functionalization and modification of desired molecules. In the approach presented here the production of various non-natural (di)amines was realized using the designed whole cell biocatalyst Escherichia coli W3110/pTrc99A-ald-adh-ta with plasmid-borne overexpression of genes for an l-alanine dehydrogenase, an alcohol dehydrogenase and a transaminase. Cascading alcohol oxidation with l-alanine dependent transamination and l-alanine dehydrogenase allowed for redox self-sufficient conversion of alcohols to the corresponding amines. The supplementation of the corresponding (di)alcohol precursors as well as amino group donor l-alanine and ammonium chloride were sufficient for amination and redox cofactor recycling in a resting buffer system. The addition of the transaminase cofactor pyridoxal-phosphate and the alcohol dehydrogenase cofactor NAD(+) was not necessary to obtain complete conversion. Secondary and cyclic alcohols, for example, 2-hexanol and cyclohexanol were not aminated. However, efficient redox self-sufficient amination of aliphatic and aromatic (di)alcohols in vivo was achieved with 1-hexanol, 1,10-decanediol and benzylalcohol being aminated best. Copyright © 2014 Elsevier Ltd. All rights reserved.

Biredox ionic liquids with solid-like redox density in the liquid state for high-energy supercapacitors.

Science.gov (United States)

Mourad, Eléonore; Coustan, Laura; Lannelongue, Pierre; Zigah, Dodzi; Mehdi, Ahmad; Vioux, André; Freunberger, Stefan A; Favier, Frédéric; Fontaine, Olivier

2017-04-01

Kinetics of electrochemical reactions are several orders of magnitude slower in solids than in liquids as a result of the much lower ion diffusivity. Yet, the solid state maximizes the density of redox species, which is at least two orders of magnitude lower in liquids because of solubility limitations. With regard to electrochemical energy storage devices, this leads to high-energy batteries with limited power and high-power supercapacitors with a well-known energy deficiency. For such devices the ideal system should endow the liquid state with a density of redox species close to the solid state. Here we report an approach based on biredox ionic liquids to achieve bulk-like redox density at liquid-like fast kinetics. The cation and anion of these biredox ionic liquids bear moieties that undergo very fast reversible redox reactions. As a first demonstration of their potential for high-capacity/high-rate charge storage, we used them in redox supercapacitors. These ionic liquids are able to decouple charge storage from an ion-accessible electrode surface, by storing significant charge in the pores of the electrodes, to minimize self-discharge and leakage current as a result of retaining the redox species in the pores, and to raise working voltage due to their wide electrochemical window.

Redox regulation of plant development.

Science.gov (United States)

Considine, Michael J; Foyer, Christine H

2014-09-20

We provide a conceptual framework for the interactions between the cellular redox signaling hub and the phytohormone signaling network that controls plant growth and development to maximize plant productivity under stress-free situations, while limiting growth and altering development on exposure to stress. Enhanced cellular oxidation plays a key role in the regulation of plant growth and stress responses. Oxidative signals or cycles of oxidation and reduction are crucial for the alleviation of dormancy and quiescence, activating the cell cycle and triggering genetic and epigenetic control that underpin growth and differentiation responses to changing environmental conditions. The redox signaling hub interfaces directly with the phytohormone network in the synergistic control of growth and its modulation in response to environmental stress, but a few components have been identified. Accumulating evidence points to a complex interplay of phytohormone and redox controls that operate at multiple levels. For simplicity, we focus here on redox-dependent processes that control root growth and development and bud burst. The multiple roles of reactive oxygen species in the control of plant growth and development have been identified, but increasing emphasis should now be placed on the functions of redox-regulated proteins, along with the central roles of reductants such as NAD(P)H, thioredoxins, glutathione, glutaredoxins, peroxiredoxins, ascorbate, and reduced ferredoxin in the regulation of the genetic and epigenetic factors that modulate the growth and vigor of crop plants, particularly within an agricultural context.

Enzymes as modular catalysts for redox half-reactions in H2-powered chemical synthesis: from biology to technology.

Science.gov (United States)

Reeve, Holly A; Ash, Philip A; Park, HyunSeo; Huang, Ailun; Posidias, Michalis; Tomlinson, Chloe; Lenz, Oliver; Vincent, Kylie A

2017-01-15

The present study considers the ways in which redox enzyme modules are coupled in living cells for linking reductive and oxidative half-reactions, and then reviews examples in which this concept can be exploited technologically in applications of coupled enzyme pairs. We discuss many examples in which enzymes are interfaced with electronically conductive particles to build up heterogeneous catalytic systems in an approach which could be termed synthetic biochemistry We focus on reactions involving the H + /H 2 redox couple catalysed by NiFe hydrogenase moieties in conjunction with other biocatalysed reactions to assemble systems directed towards synthesis of specialised chemicals, chemical building blocks or bio-derived fuel molecules. We review our work in which this approach is applied in designing enzyme-modified particles for H 2 -driven recycling of the nicotinamide cofactor NADH to provide a clean cofactor source for applications of NADH-dependent enzymes in chemical synthesis, presenting a combination of published and new work on these systems. We also consider related photobiocatalytic approaches for light-driven production of chemicals or H 2 as a fuel. We emphasise the techniques available for understanding detailed catalytic properties of the enzymes responsible for individual redox half-reactions, and the importance of a fundamental understanding of the enzyme characteristics in enabling effective applications of redox biocatalysis. © 2017 The Author(s).

The improvement of approaches to assessment of the financial condition of economic entities

Directory of Open Access Journals (Sweden)

Senko A.E.

2017-05-01

Full Text Available according to the author, the lack of unified approaches to the calculation of financial indicators, the multiple interpretations of their meanings ​​and the imperfection of information support of financial analysis hamper the effectiveness of economic entities operating under market principles. The existing approach to determining the financial condition of an enterprise does not always give the required qualitative result of an evaluation of its financial and economic activities. While analyzing the financial status of economic entities, it would be useful to take into account their industry particularities, size and organizational structure, development strategy and competitiveness in the market for goods and services.

Energy consumption and economic growth nexus in Tanzania: An ARDL bounds testing approach

International Nuclear Information System (INIS)

Odhiambo, Nicholas M.

2009-01-01

In this paper, we examine the intertemporal causal relationship between energy consumption and economic growth in Tanzania during the period of 1971-2006. Unlike the majority of the previous studies, we employ the newly developed autoregressive distributed lag (ARDL)-bounds testing approach by Pesaran et al. [2001. Bounds testing approaches to the analysis of level relationships. Journal of Applied Econometrics 16, 289-326] to examine this linkage. We also use two proxies of energy consumption, namely total energy consumption per capita and electricity consumption per capita. The results of the bounds test show that there is a stable long-run relationship between each of the proxies of energy consumption and economic growth. The results of the causality test, on the other hand, show that there is a unidirectional causal flow from total energy consumption to economic growth and a prima-facie causal flow from electricity consumption to economic growth. Overall, the study finds that energy consumption spurs economic growth in Tanzania

Energy consumption and economic growth nexus in Tanzania. An ARDL bounds testing approach

Energy Technology Data Exchange (ETDEWEB)

Odhiambo, Nicholas M. [Economics Department, University of South Africa (UNISA), P.O. Box 392, UNISA, 0003, Pretoria (South Africa)

2009-02-15

In this paper, we examine the intertemporal causal relationship between energy consumption and economic growth in Tanzania during the period of 1971-2006. Unlike the majority of the previous studies, we employ the newly developed autoregressive distributed lag (ARDL)-bounds testing approach by Pesaran et al. [2001. Bounds testing approaches to the analysis of level relationships. Journal of Applied Econometrics 16, 289-326] to examine this linkage. We also use two proxies of energy consumption, namely total energy consumption per capita and electricity consumption per capita. The results of the bounds test show that there is a stable long-run relationship between each of the proxies of energy consumption and economic growth. The results of the causality test, on the other hand, show that there is a unidirectional causal flow from total energy consumption to economic growth and a prima-facie causal flow from electricity consumption to economic growth. Overall, the study finds that energy consumption spurs economic growth in Tanzania. (author)

Energy consumption and economic growth nexus in Tanzania: An ARDL bounds testing approach

Energy Technology Data Exchange (ETDEWEB)

Odhiambo, Nicholas M. [Economics Department, University of South Africa (UNISA), P.O. Box 392, UNISA, 0003, Pretoria (South Africa)], E-mail: nmbaya99@yahoo.com

2009-02-15

In this paper, we examine the intertemporal causal relationship between energy consumption and economic growth in Tanzania during the period of 1971-2006. Unlike the majority of the previous studies, we employ the newly developed autoregressive distributed lag (ARDL)-bounds testing approach by Pesaran et al. [2001. Bounds testing approaches to the analysis of level relationships. Journal of Applied Econometrics 16, 289-326] to examine this linkage. We also use two proxies of energy consumption, namely total energy consumption per capita and electricity consumption per capita. The results of the bounds test show that there is a stable long-run relationship between each of the proxies of energy consumption and economic growth. The results of the causality test, on the other hand, show that there is a unidirectional causal flow from total energy consumption to economic growth and a prima-facie causal flow from electricity consumption to economic growth. Overall, the study finds that energy consumption spurs economic growth in Tanzania.

Economic evaluation of environmental impacts of open cast mining project - an approach

International Nuclear Information System (INIS)

Maiti, S.K.; Pathak, K.

1998-01-01

Economic valuation of environmental attributes are pragmatic approach to evaluating the impacts and it helps decision makers to arrive at objective decisions on the basis of cost benefit ratio. For determining the physical impact and its quantification, four evaluation methods, namely-market price method, surrogate market price, survey based and cost based approaches are generally used. The present paper reviews the importance of environmental evaluation of impacts of mining and also reviews a few suitable methodologies that could be effectively used for economic evaluation of environmental impacts in open cast mining projects. (author)

H-shaped oligothiophenes with low band gaps and amphoteric redox properties

KAUST Repository

Luo, Jing

2010-12-17

H-shaped bridged oligothiophenes HT-1 and HT-2 were synthesized by two different approaches. Different from normal oligothiophenes, HT-1 and HT-2 showed low band gaps and amphoteric redox behaviors due to intramolecular charge transfer, which is further supported by time-dependent DFT calculations. © 2010 American Chemical Society.

Approaches to Economic Empowerment of Rural Women for Climate ...

African Journals Online (AJOL)

There are several ways of promoting women's economic participation while also counteracting climate change. One approach in the field of climate mitigation is the promotion of renewable energies that help avoid greenhouse gas emissions. The potential of rural women as agents of change for climate mitigation and ...

Trajectories of Work Disability and Economic Insecurity Approaching Retirement.

Science.gov (United States)

Shuey, Kim M; Willson, Andrea E

2017-07-08

In this article, we examine the connection between trajectories of work disability and economic precarity in late midlife. We conceptualize work disability as a possible mechanism linking early and later life economic disadvantage. We model trajectories of work disability characterized by timing and stability for a cohort of Baby Boomers (22-32 in 1981) using 32 years of data from the Panel Study of Income Dynamics and latent class analysis. Measures of childhood disadvantage are included as predictors of work disability trajectories, which are subsequently included in logistic regression models predicting four economic outcomes (poverty, asset poverty, home ownership, and pension ownership) at ages 54-64. Childhood disadvantage selected individuals into five distinct classes of work disability that differed in timing and stability. All of the disability trajectories were associated with an increased risk of economic insecurity in late midlife compared to the never work disabled. This study contributes to the aging literature through its incorporation of the early life origins of pathways of disability and their links to economic outcomes approaching retirement. Findings suggest work disability is anchored in early life disadvantage and is associated with economic insecurity later in life. © The Author 2017. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Bounds test approach to cointegration and causality between nuclear energy consumption and economic growth in India

International Nuclear Information System (INIS)

Wolde-Rufael, Yemane

2010-01-01

This paper attempts to examine the dynamic relationship between economic growth, nuclear energy consumption, labor and capital for India for the period 1969-2006. Applying the bounds test approach to cointegration developed by we find that there was a short- and a long-run relationship between nuclear energy consumption and economic growth. Using four long-run estimators we also found that nuclear energy consumption has a positive and a statistically significant impact on India's economic growth. Further, applying the approach to Granger causality and the variance decomposition approach developed by , we found a positive and a significant uni-directional causality running from nuclear energy consumption to economic growth without feedback. This implies that economic growth in India is dependent on nuclear energy consumption where a decrease in nuclear energy consumption may lead to a decrease in real income. For a fast growing energy-dependent economy this may have far-reaching implications for economic growth. India's economic growth can be frustrated if energy conservation measures are undertaken without due regard to the negative impact they have on economic growth.

Monitoring thioredoxin redox with a genetically encoded red fluorescent biosensor.

Science.gov (United States)

Fan, Yichong; Makar, Merna; Wang, Michael X; Ai, Hui-Wang

2017-09-01

Thioredoxin (Trx) is one of the two major thiol antioxidants, playing essential roles in redox homeostasis and signaling. Despite its importance, there is a lack of methods for monitoring Trx redox dynamics in live cells, hindering a better understanding of physiological and pathological roles of the Trx redox system. In this work, we developed the first genetically encoded fluorescent biosensor for Trx redox by engineering a redox relay between the active-site cysteines of human Trx1 and rxRFP1, a redox-sensitive red fluorescent protein. We used the resultant biosensor-TrxRFP1-to selectively monitor perturbations of Trx redox in various mammalian cell lines. We subcellularly localized TrxRFP1 to image compartmentalized Trx redox changes. We further combined TrxRFP1 with a green fluorescent Grx1-roGFP2 biosensor to simultaneously monitor Trx and glutathione redox dynamics in live cells in response to chemical and physiologically relevant stimuli.

ETL 1 kW redox flow cell

International Nuclear Information System (INIS)

Nozaki, K.; Ozawa, T.

1984-01-01

A 1 kW scale redox flow cell system was set up in the laboratory (ETL), while three different types of batteries were also assembled by private companies in early 1983. In this article, this cell system is described. The concept of a modern type redox flow cell is based on a couple of fully soluble redox ions and a highly selective ion-exchange membrane. In the cell, the redox ion stored in a tank is flowed to and reduced on the electrode, while the other ion is also flowed to and oxidized on the other electrode. This electrochemical reaction produces electronic current in the external circuit and ionic current through the membrane sandwiched as a separator between the two electrodes. The reverse reaction proceeds in the charging process. In ETL, the concept was preliminarily tested, and conceptual design and cost estimation of the redox flow cells were carried out to confirm the feasibility; the R and D started on these bases in 1975

Nanostructured Electrocatalysts for All-Vanadium Redox Flow Batteries.

Science.gov (United States)

Park, Minjoon; Ryu, Jaechan; Cho, Jaephil

2015-10-01

Vanadium redox reactions have been considered as a key factor affecting the energy efficiency of the all-vanadium redox flow batteries (VRFBs). This redox reaction determines the reaction kinetics of whole cells. However, poor kinetic reversibility and catalytic activity towards the V(2+)/V(3+) and VO(2+)/VO2(+) redox couples on the commonly used carbon substrate limit broader applications of VRFBs. Consequently, modified carbon substrates have been extensively investigated to improve vanadium redox reactions. In this Focus Review, recent progress on metal- and carbon-based nanomaterials as an electrocatalyst for VRFBs is discussed in detail, without the intention to provide a comprehensive review on the whole components of the system. Instead, the focus is mainly placed on the redox chemistry of vanadium ions at a surface of various metals, different dimensional carbons, nitrogen-doped carbon nanostructures, and metal-carbon composites. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Reducing marine mammal bycatch in global fisheries: An economics approach

Science.gov (United States)

Lent, Rebecca; Squires, Dale

2017-06-01

The broader ecosystem impacts of fishing continue to present a challenge to scientists and resource managers around the world. Bycatch is of greatest concern for marine mammals, for which fishery bycatch and entanglement is the number one cause of direct mortality. Climate change will only add to the challenge, as marine species and fishing practices adapt to a changing environment, creating a dynamic pattern of overlap between fishing and species (both target and bycatch). Economists suggest policy instruments for reducing bycatch that move away from top-down, command-and-control measures (e.g. effort reduction, time/area closures, gear restrictions, bycatch quotas) towards an approach that creates incentives to reduce bycatch (e.g. transferable bycatch allowances, taxes, and other measures). The advantages of this flexible, incentive-oriented approach are even greater in a changing and increasingly variable environment, as regulatory measures would have to be adapted constantly to keep up with climate change. Unlike the regulatory process, individual operators in the fishery sector can make adjustments to their harvesting practices as soon as the incentives for such changes are apparent and inputs or operations can be modified. This paper explores policy measures that create economic incentives not only to reduce marine mammal bycatch, but also to increase compliance and induce technological advances by fishery operators. Economists also suggest exploration of direct economic incentives as have been used in other conservation programs, such as payments for economic services, in an approach that addresses marine mammal bycatch as part of a larger conservation strategy. Expanding the portfolio of mandatory and potentially, voluntary, measures to include novel approaches will provide a broader array of opportunities for successful stewardship of the marine environment.

Numerical modelling of a bromide-polysulphide redox flow battery. Part 2: Evaluation of a utility-scale system

International Nuclear Information System (INIS)

Scamman, Daniel P.; Roberts, Edward P.L.; Reade, Gavin W.

2009-01-01

Numerical modelling of redox flow battery (RFB) systems allows the technical and commercial performance of different designs to be predicted without costly lab, pilot and full-scale testing. A numerical model of a redox flow battery was used in conjunction with a simple cost model incorporating capital and operating costs to predict the technical and commercial performance of a 120 MWh/15 MW utility-scale polysulphide-bromine (PSB) storage plant for arbitrage applications. Based on 2006 prices, the system was predicted to make a net loss of 0.45 p kWh -1 at an optimum current density of 500 A m -2 and an energy efficiency of 64%. The system was predicted to become economic for arbitrage (assuming no further costs were incurred) if the rate constants of both electrolytes could be increased to 10 -5 m s -1 , for example by using a suitable (low cost) electrocatalyst. The economic viability was found to be strongly sensitive to the costs of the electrochemical cells and the electrical energy price differential. (author)

Mitochondrial redox biology and homeostasis in plants.

Science.gov (United States)

Noctor, Graham; De Paepe, Rosine; Foyer, Christine H

2007-03-01

Mitochondria are key players in plant cell redox homeostasis and signalling. Earlier concepts that regarded mitochondria as secondary to chloroplasts as the powerhouses of photosynthetic cells, with roles in cell proliferation, death and ageing described largely by analogy to animal paradigms, have been replaced by the new philosophy of integrated cellular energy and redox metabolism involving mitochondria and chloroplasts. Thanks to oxygenic photosynthesis, plant mitochondria often operate in an oxygen- and carbohydrate-rich environment. This rather unique environment necessitates extensive flexibility in electron transport pathways and associated NAD(P)-linked enzymes. In this review, mitochondrial redox metabolism is discussed in relation to the integrated cellular energy and redox function that controls plant cell biology and fate.

Institutional economics and economic organisation theory: An integrated approach

NARCIS (Netherlands)

Slangen, L.H.G.; Loucks, L.A.; Slangen, A.H.L.

2008-01-01

This publication presents one of the first attempts to integrate two emerging bodies of economic research: institutional economics and organizational theory. It begins within the framework of neoclassical economics, and then extends the boundaries of this framework to offer answers to questions that

Institutional economics and economic organisation theory : an integrated approach

NARCIS (Netherlands)

Slangen, L.H.G.; Loucks, L.; Slangen, A.H.L.

2008-01-01

This publication presents one of the first attempts to integrate two emerging bodies of economic research: institutional economics and organizational theory. It begins within the framework of neoclassical economics, and then extends the boundaries of this framework to offer answers to questions that

Subcellular Redox Targeting: Bridging in Vitro and in Vivo Chemical Biology.

Science.gov (United States)

Long, Marcus J C; Poganik, Jesse R; Ghosh, Souradyuti; Aye, Yimon

2017-03-17

Networks of redox sensor proteins within discrete microdomains regulate the flow of redox signaling. Yet, the inherent reactivity of redox signals complicates the study of specific redox events and pathways by traditional methods. Herein, we review designer chemistries capable of measuring flux and/or mimicking subcellular redox signaling at the cellular and organismal level. Such efforts have begun to decipher the logic underlying organelle-, site-, and target-specific redox signaling in vitro and in vivo. These data highlight chemical biology as a perfect gateway to interrogate how nature choreographs subcellular redox chemistry to drive precision redox biology.

Review of physical and socio-economic characteristics and intervention approaches of informal settlements

CSIR Research Space (South Africa)

Wekesa, BW

2011-04-01

Full Text Available -1 Habitat International Volume 35, Issue 2, April 2011, Pages 238-245 A review of physical and socio-economic characteristics and intervention approaches of informal settlements B.W. Wekesaa, b, , , G.S. Steyna, 1, , F.A.O. (Fred) Otienoc, 2, , a... a literature survey, this paper reviews physical and socio-economic characteristics and the factors attributed to proliferation of the informal settlements and intervention approaches. The main objective was to establish how such settlements could...

Neutral Red and Ferroin as Reversible and Rapid Redox Materials for Redox Flow Batteries.

Science.gov (United States)

Hong, Jeehoon; Kim, Ketack

2018-04-17

Neutral red and ferroin are used as redox indicators (RINs) in potentiometric titrations. The rapid response and reversibility that are prerequisites for RINs are also desirable properties for the active materials in redox flow batteries (RFBs). This study describes the electrochemical properties of ferroin and neutral red as a redox pair. The rapid reaction rates of the RINs allow a cell to run at a rate of 4 C with 89 % capacity retention after the 100 th  cycle. The diffusion coefficients, electrode reaction rates, and solubilities of the RINs were determined. The electron-transfer rate constants of ferroin and neutral red are 0.11 and 0.027 cm s -1 , respectively, which are greater than those of the components of all-vanadium and Zn/Br 2 cells. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Redox shuttles for safer lithium-ion batteries

International Nuclear Information System (INIS)

Chen, Zonghai; Qin, Yan; Amine, Khalil

2009-01-01

Overcharge protection is not only critical for preventing the thermal runaway of lithium-ion batteries during operation, but also important for automatic capacity balancing during battery manufacturing and repair. A redox shuttle is an electrolyte additive that can be used as intrinsic overcharge protection mechanism to enhance the safety characteristics of lithium-ion batteries. The advances on stable redox shuttles are briefly reviewed. Fundamental studies for designing stable redox shuttles are also discussed.

Microfluidic redox battery.

Science.gov (United States)

Lee, Jin Wook; Goulet, Marc-Antoni; Kjeang, Erik

2013-07-07

A miniaturized microfluidic battery is proposed, which is the first membraneless redox battery demonstrated to date. This unique concept capitalizes on dual-pass flow-through porous electrodes combined with stratified, co-laminar flow to generate electrical power on-chip. The fluidic design is symmetric to allow for both charging and discharging operations in forward, reverse, and recirculation modes. The proof-of-concept device fabricated using low-cost materials integrated in a microfluidic chip is shown to produce competitive power levels when operated on a vanadium redox electrolyte. A complete charge/discharge cycle is performed to demonstrate its operation as a rechargeable battery, which is an important step towards providing sustainable power to lab-on-a-chip and microelectronic applications.

Managing the cellular redox hub in photosynthetic organisms.

Science.gov (United States)

Foyer, Christine H; Noctor, Graham

2012-02-01

Light-driven redox chemistry is a powerful source of redox signals that has a decisive input into transcriptional control within the cell nucleus. Like photosynthetic electron transport pathways, the respiratory electron transport chain exerts a profound control over gene function, in order to balance energy (reductant and ATP) supply with demand, while preventing excessive over-reduction or over-oxidation that would be adversely affect metabolism. Photosynthetic and respiratory redox chemistries are not merely housekeeping processes but they exert a controlling influence over every aspect of plant biology, participating in the control of gene transcription and translation, post-translational modifications and the regulation of assimilatory reactions, assimilate partitioning and export. The number of processes influenced by redox controls and signals continues to increase as do the components that are recognized participants in the associated signalling pathways. A step change in our understanding of the overall importance of the cellular redox hub to plant cells has occurred in recent years as the complexity of the management of the cellular redox hub in relation to metabolic triggers and environmental cues has been elucidated. This special issue describes aspects of redox regulation and signalling at the cutting edge of current research in this dynamic and rapidly expanding field. © 2011 Blackwell Publishing Ltd.

Unusual thiol-based redox metabolism of parasitic flukes.

Science.gov (United States)

Tripathi, Timir; Suttiprapa, Sutas; Sripa, Banchob

2017-08-01

Parasitic flukes are exposed to free radicals and, to a greater extent, reactive oxygen species (ROS) during their life cycle. Despite being relentlessly exposed to ROS released by activated immune cells, these parasites can survive for many years in the host. Cellular thiol-based redox metabolism plays a crucial role in parasite survival within their hosts. Evidence shows that oxidative stress and redox homeostasis maintenance are important clinical and pathobiochemical as well as effective therapeutic principles in various diseases. The characterization of redox and antioxidant enzymes is likely to yield good target candidates for novel drugs and vaccines. The absence of active catalase in fluke parasites offers great potential for the development of chemotherapeutic agents that act by perturbing the redox equilibrium of the cell. One of the redox-sensitive enzymes, thioredoxin glutathione reductase (TGR), has been accepted as a drug target against blood fluke infections, and related clinical trials are in progress. TGR is the sole enzyme responsible for Trx and GSH reduction in parasitic flukes. The availability of helminth genomes has accelerated the research on redox metabolism of flukes; however, significant achievements have yet to be attained. The present review summarizes current knowledge on the redox and antioxidant system of the parasitic flukes. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Redox Reactivity of Cerium Oxide Nanoparticles Induces the Formation of Disulfide Bridges in Thiol-Containing Biomolecules.

Science.gov (United States)

Rollin-Genetet, Françoise; Seidel, Caroline; Artells, Ester; Auffan, Mélanie; Thiéry, Alain; Vidaud, Claude

2015-12-21

The redox state of disulfide bonds is implicated in many redox control systems, such as the cysteine-cystine couple. Among proteins, ubiquitous cysteine-rich metallothioneins possess thiolate metal binding groups susceptible to metal exchange in detoxification processes. CeO2 NPs are commonly used in various industrial applications due to their redox properties. These redox properties that enable dual oxidation states (Ce(IV)/Ce(III)) to exist at their surface may act as oxidants for biomolecules. The interaction among metallothioneins, cysteine, and CeO2 NPs was investigated through various biophysical approaches to shed light on the potential effects of the Ce(4+)/Ce(3+) redox system on the thiol groups of these biomolecules. The possible reaction mechanisms include the formation of a disulfide bridge/Ce(III) complex resulting from the interaction between Ce(IV) and the thiol groups, leading to metal unloading from the MTs, depending on their metal content and cluster type. The formation of stable Ce(3+) disulfide complexes has been demonstrated via their fluorescence properties. This work provides the first evidence of thiol concentration-dependent catalytic oxidation mechanisms between pristine CeO2 NPs and thiol-containing biomolecules.

Redox Modulations, Antioxidants, and Neuropsychiatric Disorders

Directory of Open Access Journals (Sweden)

Erik A. Fraunberger

2016-01-01

Full Text Available Although antioxidants, redox modulations, and neuropsychiatric disorders have been widely studied for many years, the field would benefit from an integrative and corroborative review. Our primary objective is to delineate the biological significance of compounds that modulate our redox status (i.e., reactive species and antioxidants as well as outline their current role in brain health and the impact of redox modulations on the severity of illnesses. Therefore, this review will not enter into the debate regarding the perceived medical legitimacy of antioxidants but rather seek to clarify their abilities and limitations. With this in mind, antioxidants may be interpreted as natural products with significant pharmacological actions in the body. A renewed understanding of these often overlooked compounds will allow us to critically appraise the current literature and provide an informed, novel perspective on an important healthcare issue. In this review, we will introduce the complex topics of redox modulations and their role in the development of select neuropsychiatric disorders.

Two approaches to meeting the economic challenge for advanced BWR designs

International Nuclear Information System (INIS)

Arnold, H.; Rao, A.S.; Sawyer, C.D.

1996-01-01

In developing next generation nuclear power plants many economic challenges must be addressed before they become economically attractive to utilities. The economic challenges vary from country to country but have several common characteristics. First and foremost, a plant has to have the lowest construction (costs) to even be considered for design and construction. Additionally, the plant design has to a have a reasonable chance of being licensed by the regulatory authorities in order to minimize the financial risk to the constructing utility. With the long lead times involved in the design and development of advanced plants nowadays, the overall development costs have also become a key factor in the evolution of advanced plants. This paper presents the design overview and approach to addressing the aforementioned economic challenges for two Advanced Boiling Water Reactor (ABWR) designs. The first plant is the ABWR and the second is the European Simplified Boiling Water. The ABWR relies on proven technology and components and an extensive infrastructure that has been built up over the last 20 year. Because it has proven and standard safety systems, which have been licensed in two countries, it has very limited uncertainly regarding licensing. Finally, it relies on the economies of scale and design flexibility to improve the overall economics of power generation. The ESBWR on the other hand has taken an innovative approach to reduce systems and components to simplify the overall plant to improve plant economics. The overall plant design is indeed simpler, but improved economics required reliance on some economies of scale also. This design embodied in the ESBWR, also has minimized the overall development cost by utilizing features and components from the ABWR and Simplified Boiling Water Reactor technology programs. (authors)

Measuring intracellular redox conditions using GFP-based sensors

DEFF Research Database (Denmark)

Björnberg, Olof; Ostergaard, Henrik; Winther, Jakob R

2006-01-01

Recent years have seen the development of methods for analyzing the redox conditions in specific compartments in living cells. These methods are based on genetically encoded sensors comprising variants of Green Fluorescent Protein in which vicinal cysteine residues have been introduced at solvent......-exposed positions. Several mutant forms have been identified in which formation of a disulfide bond between these cysteine residues results in changes of their fluorescence properties. The redox sensors have been characterized biochemically and found to behave differently, both spectroscopically and in terms...... of redox properties. As genetically encoded sensors they can be expressed in living cells and used for analysis of intracellular redox conditions; however, which parameters are measured depends on how the sensors interact with various cellular redox components. Results of both biochemical and cell...

Characterization of redox proteins using electrochemical methods

OpenAIRE

Verhagen, M.

1995-01-01

The use of electrochemical techniques in combination with proteins started approximately a decade ago and has since then developed into a powerfull technique for the study of small redox proteins. In addition to the determination of redox potentials, electrochemistry can be used to obtain information about the kinetics of electron transfer between proteins and about the dynamic behaviour of redox cofactors in proteins. This thesis describes the results of a study, initiated to get a ...

Dihydroxybenzene/benzoquinone-containing polymers: organic redox polymers

Energy Technology Data Exchange (ETDEWEB)

Moulay, S. [Universite de Blida, Lab. de Chimie-Physique Macromoleculaire, Institut de Chimie Industrielle (Algeria)

2000-08-01

Polymers containing hydroquinone, catechol or their corresponding benzoquinones are a special class of redox polymers. Three pathways of their syntheses are possible: condensation polymerization of suitable monomers, addition polymerization of vinyl monomers containing redox moiety, and chemical attachment of redox unit onto pre-made polymeric matrix. A range of functionalized matrices have been employed such as polyethers, polyesters, polycarbonates, polyurethanes, polyamides and others. Protection of their phenolic functionality has conducted to chemically interesting redox polymer precursors. The presence of a redox moiety coupled with the extant functionalization of the polymer matrix makes the materials very valuable, of wide properties and consequently of vast applicability. For instance, in the oil field, some polymers such as carboxy-methyl-cellulose (CMC) are often applied as to bring about a viscosity improvement and therefore to facilitate the oil drilling. In this regard, Patel evaluated sulfo-alkylated polymeric catechol, namely sulfo-methylated and sulfo-ethylated resins. Indeed, polymeric catechol chemically modified as such exhibited a marked ability to control the viscosity, the gel strength, as well as the filtrate loss of aqueous oil drilling fluids.

State of charge monitoring of vanadium redox flow batteries using half cell potentials and electrolyte density

Science.gov (United States)

Ressel, Simon; Bill, Florian; Holtz, Lucas; Janshen, Niklas; Chica, Antonio; Flower, Thomas; Weidlich, Claudia; Struckmann, Thorsten

2018-02-01

The operation of vanadium redox flow batteries requires reliable in situ state of charge (SOC) monitoring. In this study, two SOC estimation approaches for the negative half cell are investigated. First, in situ open circuit potential measurements are combined with Coulomb counting in a one-step calibration of SOC and Nernst potential which doesn't need additional reference SOCs. In-sample and out-of-sample SOCs are estimated and analyzed, estimation errors ≤ 0.04 are obtained. In the second approach, temperature corrected in situ electrolyte density measurements are used for the first time in vanadium redox flow batteries for SOC estimation. In-sample and out-of-sample SOC estimation errors ≤ 0.04 demonstrate the feasibility of this approach. Both methods allow recalibration during battery operation. The actual capacity obtained from SOC calibration can be used in a state of health model.

Mesoporous tungsten oxynitride as electrocatalyst for promoting redox reactions of vanadium redox couple and performance of vanadium redox flow battery

Science.gov (United States)

Lee, Wonmi; Jo, Changshin; Youk, Sol; Shin, Hun Yong; Lee, Jinwoo; Chung, Yongjin; Kwon, Yongchai

2018-01-01

For enhancing the performance of vanadium redox flow battery (VRFB), a sluggish reaction rate issue of V2+/V3+ redox couple evaluated as the rate determining reaction should be addressed. For doing that, mesoporous tungsten oxide (m-WO3) and oxyniride (m-WON) structures are proposed as the novel catalysts, while m-WON is gained by NH3 heat treatment of m-WO3. Their specific surface area, crystal structure, surface morphology and component analysis are measured using BET, XRD, TEM and XPS, while their catalytic activity for V2+/V3+ redox reaction is electrochemically examined. As a result, the m-WON shows higher peak current, smaller peak potential difference, higher electron transfer rate constant and lower charge transfer resistance than other catalysts, like the m-WO3, WO3 nanoparticle and mesoporous carbon, proving that it is superior catalyst. Regarding the charge-discharge curve tests, the VRFB single cell employing the m-WON demonstrates high voltage and energy efficiencies, high specific capacity and low capacity loss rate. The excellent results of m-WON are due to the reasons like (i) reduced energy band gap, (ii) reaction familiar surface functional groups and (ii) greater electronegativity.

Another look at economic approaches to environmental management and policy with reference to developments in South Africa

Directory of Open Access Journals (Sweden)

Martin De Wit

2016-12-01

Full Text Available The wide acceptance of economic approaches to environmental management and policy, masks increasing heterogeneity in the field. This editorial addresses the question whether the economic approach is still warranted and under which conditions. A broad outline of the trends in both orthodox and heterodox economic approaches is also presented. The traditional split between environmental and ecological economics is not doing justice to recent developments in the field. Instead it is proposed to rather refer to Environmental, Resource and Ecological Economics (EREE, Ecological-Economic Systems (EES and Socio-Ecological Systems (SES approaches as well as Heterodox approaches to Environment and Sustainability (HEES. The contributions made to this special issue are placed within their respective subfields of influence. It is concluded that a deeper, self-critical exposition of moral philosophies and values as well as models of reality are needed. A strategy of engagement in an attitude of self-criticism, humility and in participation with others is proposed as a viable way forward. For such a process to be successful two conditions are required, namely valuing the human person and accepting the reality of a nondeterminate world full of meaning.

A participatory systems approach to modeling social, economic, and ecological components of bioenergy

International Nuclear Information System (INIS)

Buchholz, Thomas S.; Volk, Timothy A.; Luzadis, Valerie A.

2007-01-01

Availability of and access to useful energy is a crucial factor for maintaining and improving human well-being. Looming scarcities and increasing awareness of environmental, economic, and social impacts of conventional sources of non-renewable energy have focused attention on renewable energy sources, including biomass. The complex interactions of social, economic, and ecological factors among the bioenergy system components of feedstock supply, conversion technology, and energy allocation have been a major obstacle to the broader development of bioenergy systems. For widespread implementation of bioenergy to occur there is a need for an integrated approach to model the social, economic, and ecological interactions associated with bioenergy. Such models can serve as a planning and evaluation tool to help decide when, where, and how bioenergy systems can contribute to development. One approach to integrated modeling is by assessing the sustainability of a bioenergy system. The evolving nature of sustainability can be described by an adaptive systems approach using general systems principles. Discussing these principles reveals that participation of stakeholders in all components of a bioenergy system is a crucial factor for sustainability. Multi-criteria analysis (MCA) is an effective tool to implement this approach. This approach would enable decision-makers to evaluate bioenergy systems for sustainability in a participatory, transparent, timely, and informed manner

Vascular remodeling: A redox-modulated mechanism of vessel caliber regulation.

Science.gov (United States)

Tanaka, Leonardo Y; Laurindo, Francisco R M

2017-08-01

Vascular remodeling, i.e. whole-vessel structural reshaping, determines lumen caliber in (patho)physiology. Here we review mechanisms underlying vessel remodeling, with emphasis in redox regulation. First, we discuss confusing terminology and focus on strictu sensu remodeling. Second, we propose a mechanobiological remodeling paradigm based on the concept of tensional homeostasis as a setpoint regulator. We first focus on shear-mediated models as prototypes of remodeling closely dominated by highly redox-sensitive endothelial function. More detailed discussions focus on mechanosensors, integrins, extracellular matrix, cytoskeleton and inflammatory pathways as potential of mechanisms potentially coupling tensional homeostasis to redox regulation. Further discussion of remodeling associated with atherosclerosis and injury repair highlights important aspects of redox vascular responses. While neointima formation has not shown consistent responsiveness to antioxidants, vessel remodeling has been more clearly responsive, indicating that despite the multilevel redox signaling pathways, there is a coordinated response of the whole vessel. Among mechanisms that may orchestrate redox pathways, we discuss roles of superoxide dismutase activity and extracellular protein disulfide isomerase. We then discuss redox modulation of aneurysms, a special case of expansive remodeling. We propose that the redox modulation of vascular remodeling may reflect (1) remodeling pathophysiology is dominated by a particularly redox-sensitive cell type, e.g., endothelial cells (2) redox pathways are temporospatially coordinated at an organ level across distinct cellular and acellular structures or (3) the tensional homeostasis setpoint is closely connected to redox signaling. The mechanobiological/redox model discussed here can be a basis for improved understanding of remodeling and helps clarifying mechanisms underlying prevalent hard-to-treat diseases. Copyright © 2017 Elsevier Inc. All

Redox-Based Regulation of Bacterial Development and Behavior.

Science.gov (United States)

Sporer, Abigail J; Kahl, Lisa J; Price-Whelan, Alexa; Dietrich, Lars E P

2017-06-20

Severe changes in the environmental redox potential, and resulting alterations in the oxidation states of intracellular metabolites and enzymes, have historically been considered negative stressors, requiring responses that are strictly defensive. However, recent work in diverse organisms has revealed that more subtle changes in the intracellular redox state can act as signals, eliciting responses with benefits beyond defense and detoxification. Changes in redox state have been shown to influence or trigger chromosome segregation, sporulation, aerotaxis, and social behaviors, including luminescence as well as biofilm establishment and dispersal. Connections between redox state and complex behavior allow bacteria to link developmental choices with metabolic state and coordinate appropriate responses. Promising future directions for this area of study include metabolomic analysis of species- and condition-dependent changes in metabolite oxidation states and elucidation of the mechanisms whereby the redox state influences circadian regulation.

Redox flow batteries having multiple electroactive elements

Energy Technology Data Exchange (ETDEWEB)

Wang, Wei; Li, Liyu; Yang, Zhenguo; Nie, Zimin

2018-05-01

Introducing multiple redox reactions with a suitable voltage range can improve the energy density of redox flow battery (RFB) systems. One example includes RFB systems utilizing multiple redox pairs in the positive half cell, the negative half cell, or in both. Such RFB systems can have a negative electrolyte, a positive electrolyte, and a membrane between the negative electrolyte and the positive electrolyte, in which at least two electrochemically active elements exist in the negative electrolyte, the positive electrolyte, or both.

Vanadium redox flow batteries to reach greenhouse gas emissions targets in an off-grid configuration

International Nuclear Information System (INIS)

Arbabzadeh, Maryam; Johnson, Jeremiah X.; De Kleine, Robert; Keoleian, Gregory A.

2015-01-01

Highlights: • We assess energy storage role in reaching emissions targets in an off-grid model. • The energy storage technology is vanadium redox flow battery (VRFB). • We evaluate life cycle GHG emissions and total cost of delivered electricity. • Generation mixes are optimized to meet emissions targets at the minimum cost. • For this model, integrating VRFB is economical to reach very low emissions targets. - Abstract: Energy storage may serve as a solution to the integration challenges of high penetrations of wind, helping to reduce curtailment, provide system balancing services, and reduce emissions. This study determines the minimum cost configuration of vanadium redox flow batteries (VRFB), wind turbines, and natural gas reciprocating engines in an off-grid model. A life cycle assessment (LCA) model is developed to determine the system configuration needed to achieve a variety of CO 2 -eq emissions targets. The relationship between total system costs and life cycle emissions are used to optimize the generation mixes to achieve emissions targets at the least cost and determine when VRFBs are preferable over wind curtailment. Different greenhouse gas (GHG) emissions targets are defined for the off-grid system and the minimum cost resource configuration is determined to meet those targets. This approach determines when the use of VRFBs is more cost effective than wind curtailment in reaching GHG emissions targets. The research demonstrates that while incorporating energy storage consistently reduces life cycle carbon emissions, it is not cost effective to reduce curtailment except under very low emission targets (190 g of CO2-eq/kW h and less for the examined system). This suggests that “overbuilding” wind is a more viable option to reduce life cycle emissions for all but the most ambitious carbon mitigation targets. The findings show that adding VRFB as energy storage could be economically preferable only when wind curtailment exceeds 66% for the

Economic Sustainability in International Business: Peculiarities, Methods and Approaches

Directory of Open Access Journals (Sweden)

Otenko Iryna Pavlivna

2016-05-01

Full Text Available This article is intended as a contribution to the ongoing analysis of economic sustainability in international business. This study is presented with a view toward further understanding and agreement of the key concepts of sustainability. Approaches to sustainability are considered, important benchmarks and essential characteristics of sustainable development in international business are included. The article demonstrates how the concept of economic sustainability can be applied to the business level. The main ideas of the most widespread concepts on resource management are presented. Incorporation of ESG and financial factors in the concept of sustainable investing is considered. Emissions that are responsible for climate change, namely top emitters, key issues and figures are presented.

Redox Cycling Realized in Paper-Based Biochemical Sensor for Selective Detection of Reversible Redox Molecules Without Micro/Nano Fabrication Process.

Science.gov (United States)

Yamamoto, So; Uno, Shigeyasu

2018-02-28

This paper describes a paper-based biochemical sensor that realizes redox cycling with close interelectrode distance. Two electrodes, the generator and collector electrodes, can detect steady-state oxidation and reduction currents when suitable potential is held at each electrode. The sensor has two gold plates on both sides of a piece of chromatography paper and defines the interelectrode distance by the thickness of the paper (180 μm) without any micro-fabrication processes. Our proposed sensor geometry has successfully exhibited signatures of redox cycling. As a result, the concentration of ferrocyanide as reversible redox molecules was successfully quantified under the interference by ascorbic acid as a strong irreversible reducing agent. This was possible because the ascorbic acids are completely consumed by the irreversible reaction, while maintaining redox cycling of reversible ferrocyanide. This suggests that a sensor based on the redox cycling method will be suitable for detecting target molecules at low concentration.

Redox front penetration in the fractured Toki Granite, central Japan: An analogue for redox reactions and redox buffering in fractured crystalline host rocks for repositories of long-lived radioactive waste

International Nuclear Information System (INIS)

Yamamoto, Koshi; Yoshida, Hidekazu; Akagawa, Fuminori; Nishimoto, Shoji; Metcalfe, Richard

2013-01-01

Highlights: • Deep redox front developed in orogenic granitic rock have been studied. • The process was controlled by the buffering capacity of minerals. • This is an analogue of redox front penetration into HLW repositories in Japan. - Abstract: Redox buffering is one important factor to be considered when assessing the barrier function of potential host rocks for a deep geological repository for long-lived radioactive waste. If such a repository is to be sited in fractured crystalline host rock it must be demonstrated that waste will be emplaced deeper than the maximum depth to which oxidizing waters can penetrate from the earth’s surface via fractures, during the assessment timeframe (typically 1 Ma). An analogue for penetration of such oxidizing water occurs in the Cretaceous Toki Granite of central Japan. Here, a deep redox front is developed along water-conducting fractures at a depth of 210 m below the ground surface. Detailed petrographical studies and geochemical analyses were carried out on drill core specimens of this redox front. The aim was to determine the buffering processes and behavior of major and minor elements, including rare earth elements (REEs), during redox front development. The results are compared with analytical data from an oxidized zone found along shallow fractures (up to 20 m from the surface) in the same granitic rock, in order to understand differences in elemental migration according to the depth below the ground surface of redox-front formation. Geochemical analyses by XRF and ICP-MS of the oxidized zone at 210 m depth reveal clear changes in Fe(III)/Fe(II) ratios and Ca depletion across the front, while Fe concentrations vary little. In contrast, the redox front identified along shallow fractures shows strong enrichments of Fe, Mn and trace elements in the oxidized zone compared with the fresh rock matrix. The difference can be ascribed to the changing Eh and pH of groundwater as it flows downwards in the granite, due to

Enhancing Capacity Performance by Utilizing the Redox Chemistry of the Electrolyte in a Dual-Electrolyte Sodium-Ion Battery.

Science.gov (United States)

Senthilkumar, Sirugaloor Thangavel; Bae, Hyuntae; Han, Jinhyup; Kim, Youngsik

2018-05-04

A strategy is described to increase charge storage in a dual electrolyte Na-ion battery (DESIB) by combining the redox chemistry of the electrolyte with a Na + ion de-insertion/insertion cathode. Conventional electrolytes do not contribute to charge storage in battery systems, but redox-active electrolytes augment this property via charge transfer reactions at the electrode-electrolyte interface. The capacity of the cathode combined with that provided by the electrolyte redox reaction thus increases overall charge storage. An aqueous sodium hexacyanoferrate (Na 4 Fe(CN) 6 ) solution is employed as the redox-active electrolyte (Na-FC) and sodium nickel Prussian blue (Na x -NiBP) as the Na + ion insertion/de-insertion cathode. The capacity of DESIB with Na-FC electrolyte is twice that of a battery using a conventional (Na 2 SO 4 ) electrolyte. The use of redox-active electrolytes in batteries of any kind is an efficient and scalable approach to develop advanced high-energy-density storage systems. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Factors Controlling Redox Speciation of Plutonium and Neptunium in Extraction Separation Processes

Energy Technology Data Exchange (ETDEWEB)

Paulenova, Alena [Principal Investigator; Vandegrift, III, George F. [Collaborator

2013-09-24

The objective of the project was to examine the factors controlling redox speciation of plutonium and neptunium in UREX+ extraction in terms of redox potentials, redox mechanism, kinetics and thermodynamics. Researchers employed redox-speciation extractions schemes in parallel to the spectroscopic experiments. The resulting distribution of redox species w studied uring spectroscopic, electrochemical, and spectro-electrochemical methods. This work reulted in collection of data on redox stability and distribution of redox couples in the nitric acid/nitrate electrolyte and the development of redox buffers to stabilize the desired oxidation state of separated radionuclides. The effects of temperature and concentrations on the redox behavior of neptunium were evaluated.

Regulating the Relationship between State and Religion: An Economic Approach

NARCIS (Netherlands)

A.M.I.B. Vandenberghe (Ann-Sophie)

2012-01-01

markdownabstract__Abstract__ In defining its relationship towards religion, the Dutch government is committed to the values of freedom of religion and neutrality. This article uses the economic approach to freedom of religion and state neutrality as a tool for looking at the existing Dutch policy

Single-molecule conductivity of non-redox and redox molecules at pure and gold-mined Au(111)-electrode surfaces

DEFF Research Database (Denmark)

Zhang, Jingdong; Chi, Qijin; Ulstrup, Jens

The structure, two-dimensional organization, and function of molecules immobilized on solid surfaces can be addressed in a degree of detail that has reached the level of the single-molecule. In this context redox molecules are “smart” molecules adding sophisticated electronic function. Redox meta...

Compartmentation of redox metabolism in malaria parasites.

Directory of Open Access Journals (Sweden)

Sebastian Kehr

Full Text Available Malaria, caused by the apicomplexan parasite Plasmodium, still represents a major threat to human health and welfare and leads to about one million human deaths annually. Plasmodium is a rapidly multiplying unicellular organism undergoing a complex developmental cycle in man and mosquito - a life style that requires rapid adaptation to various environments. In order to deal with high fluxes of reactive oxygen species and maintain redox regulatory processes and pathogenicity, Plasmodium depends upon an adequate redox balance. By systematically studying the subcellular localization of the major antioxidant and redox regulatory proteins, we obtained the first complete map of redox compartmentation in Plasmodium falciparum. We demonstrate the targeting of two plasmodial peroxiredoxins and a putative glyoxalase system to the apicoplast, a non-photosynthetic plastid. We furthermore obtained a complete picture of the compartmentation of thioredoxin- and glutaredoxin-like proteins. Notably, for the two major antioxidant redox-enzymes--glutathione reductase and thioredoxin reductase--Plasmodium makes use of alternative-translation-initiation (ATI to achieve differential targeting. Dual localization of proteins effected by ATI is likely to occur also in other Apicomplexa and might open new avenues for therapeutic intervention.

Bioelectrochemical probing of intracellular redox processes in living yeast cells—application of redox polymer wiring in a microfluidic environment

DEFF Research Database (Denmark)

Heiskanen, Arto; Coman, Vasile; Kostesha, Natalie

2013-01-01

utilizing a new double mediator system to map redox metabolism and screen for genetic modifications in Saccharomyces cerevisiae cells. The function of this new double mediator system based on menadione and osmium redox polymer (PVI-Os) is demonstrated. “Wiring” of S. cerevisiae cells using PVI-Os shows...... that microfluidic bioelectrochemical assays employing the menadione–PVI-Os double mediator system provides an effective means to conduct automated microbial assays. FigureMicrofluidic platform for bioelectrochemical assays using osmium redox polymer “wired” living yeast cells...

Decision-theoretic approaches to non-knowledge in economics

OpenAIRE

Svetlova, Ekaterina; van Elst, Henk

2014-01-01

We review two strands of conceptual approaches to the formal representation of a decision maker's non-knowledge at the initial stage of a static one-person, one-shot decision problem in economic theory. One focuses on representations of non-knowledge in terms of probability measures over sets of mutually exclusive and exhaustive consequence-relevant states of Nature, the other deals with unawareness of potentially important events by means of sets of states that are less complete than the ful...

Approaches based on behavioral economics could help nudge patients and providers toward lower health spending growth.

Science.gov (United States)

King, Dominic; Greaves, Felix; Vlaev, Ivo; Darzi, Ara

2013-04-01

Policies that change the environment or context in which decisions are made and "nudge" people toward particular choices have been relatively ignored in health care. This article examines the role that approaches based on behavioral economics could play in "nudging" providers and patients in ways that could slow health care spending growth. The basic insight of behavioral economics is that behavior is guided by the very fallible human brain and greatly influenced by the environment or context in which choices are made. In policy arenas such as pensions and personal savings, approaches based on behavioral economics have provided notable results. In health care, such approaches have been used successfully but in limited ways, as in the use of surgical checklists that have increased patient safety and reduced costs. With health care spending climbing at unsustainable rates, we review the role that approaches based on behavioral economics could play in offering policy makers a potential set of new tools to slow spending growth.

Economic culture of the Tuvans within the scope of the sociocultural approach

Directory of Open Access Journals (Sweden)

Yuri V. Popkov

2018-06-01

Full Text Available In this article, the authors argue that for the periods of social turmoil, understanding culture as a set of norms controlling social behavior is limited and insufficient. A more adequate approach would involve interpreting culture as a specific historical version of the society’s existence in its qualitative form. This hearkens back to the sociocultural approach which postulates the culture as an ensemble, and the sociocultural construed as the social in the cultural variety. In this context, economic culture might be seen as a set of qualitative features of a specific economic entity shaped by the local conditions of development. With all its peculiarities, an economic culture appears an element of this sociocultural diversity. Studying the economic culture of Tuvans through the lens of the sociocultural approach and the notion of this diversity allows us to outline several important aspects of this issue, rarely addressed by the existing academic discourse. A focus should be made, for instance, not only on the dominant nomadic culture, but also on subdominant economic cultures which helped shape a number of skills and techniques. While nomadism helped develop unhurried and contemplative attitude to life, hunting demanded dynamic change, and agriculture and crafts called for diligence and meticulousness. A brief glance at the economic history of Tuvans allowed the authors to conclude that economic diversity both provides stability to the economic culture of Tuvan society and expresses its variegation, its capacity to develop through numerous modifications. This polymorphism acts as an important resource which helps launch the alternate routes of ethnic development. These routes rarely appear self-evident under the dominant type of economic culture which had been shaping the traditional life of Tuvan society. Tapping into this alternative potential can prove an important reserve for future development. An overview of ethnographic data helps

Biofabricated film with enzymatic and redox-capacitor functionalities to harvest and store electrons

International Nuclear Information System (INIS)

Liba, Benjamin D; Kim, Eunkyoung; Martin, Alexandra N; Liu Yi; Bentley, William E; Payne, Gregory F

2013-01-01

Exciting opportunities in bioelectronics will be facilitated by materials that can bridge the chemical logic of biology and the digital logic of electronics. Here we report the fabrication of a dual functional hydrogel film that can harvest electrons from its chemical environment and store these electrons by switching the film's redox-state. The hydrogel scaffold was formed by the anodic deposition of the aminopolysaccharide chitosan. Electron-harvesting function was conferred by co-depositing the enzyme glucose dehydrogenase (GDH) with chitosan. GDH catalyzes the transfer of electrons from glucose to the soluble redox-shuttle NADP + . Electron-storage function was conferred by the redox-active food phenolic chlorogenic acid (CA) that was enzymatically grafted to the chitosan scaffold using tyrosinase. The grafted CA undergoes redox-cycling reactions with NADPH resulting in the net transfer of electrons to the film where they are stored in the reduced state of CA. The individual and dual functionalities of these films were demonstrated experimentally. There are three general conclusions from this proof-of-concept study. First, enzymatically-grafted catecholic moieties confer redox-capacitor function to the chitosan scaffold. Second, biological materials (i.e. chitosan and CA) and mechanisms (i.e. tyrosinase-mediated grafting) allow the reagentless fabrication of functional films that should be environmentally-friendly, safe and potentially even edible. Finally, the film's ability to mediate the transfer of electrons from a biological metabolite to an electrode suggests an approach to bridge the chemical logic of biology with the digital logic of electronics. (paper)

High-Performance Oligomeric Catholytes for Effective Macromolecular Separation in Nonaqueous Redox Flow Batteries.

Science.gov (United States)

Hendriks, Koen H; Robinson, Sophia G; Braten, Miles N; Sevov, Christo S; Helms, Brett A; Sigman, Matthew S; Minteer, Shelley D; Sanford, Melanie S

2018-02-28

Nonaqueous redox flow batteries (NRFBs) represent an attractive technology for energy storage from intermittent renewable sources. In these batteries, electrical energy is stored in and extracted from electrolyte solutions of redox-active molecules (termed catholytes and anolytes) that are passed through an electrochemical flow cell. To avoid battery self-discharge, the anolyte and catholyte solutions must be separated by a membrane in the flow cell. This membrane prevents crossover of the redox active molecules, while simultaneously allowing facile transport of charge-balancing ions. A key unmet challenge for the field is the design of redox-active molecule/membrane pairs that enable effective electrolyte separation while maintaining optimal battery properties. Herein, we demonstrate the development of oligomeric catholytes based on tris(dialkylamino)cyclopropenium (CP) salts that are specifically tailored for pairing with size-exclusion membranes composed of polymers of intrinsic microporosity (PIMs). Systematic studies were conducted to evaluate the impact of oligomer size/structure on properties that are crucial for flow battery performance, including cycling stability, charge capacity, solubility, electron transfer kinetics, and crossover rates. These studies have led to the identification of a CP-derived tetramer in which these properties are all comparable, or significantly improved, relative to the monomeric counterpart. Finally, a proof-of-concept flow battery is demonstrated by pairing this tetrameric catholyte with a PIM membrane. After 6 days of cycling, no crossover is detected, demonstrating the promise of this approach. These studies provide a template for the future design of other redox-active oligomers for this application.

Redox properties of small semiconductor particles

International Nuclear Information System (INIS)

Liver, N.; Nitzan, A.

1992-01-01

The size dependence of electrical and thermodynamic quantities of intermediate-sized semiconductor particles in an electrolyte solution with a given redox pair are studied. The equilibrium constant for this system is then derived based on the relationship of the electrolytic redox components to the size, charges, and concentration of the semiconductor particles. 25 refs., 9 figs., 1 tab

New tools for redox biology: From imaging to manipulation.

Science.gov (United States)

Bilan, Dmitry S; Belousov, Vsevolod V

2017-08-01

Redox reactions play a key role in maintaining essential biological processes. Deviations in redox pathways result in the development of various pathologies at cellular and organismal levels. Until recently, studies on transformations in the intracellular redox state have been significantly hampered in living systems. The genetically encoded indicators, based on fluorescent proteins, have provided new opportunities in biomedical research. The existing indicators already enable monitoring of cellular redox parameters in different processes including embryogenesis, aging, inflammation, tissue regeneration, and pathogenesis of various diseases. In this review, we summarize information about all genetically encoded redox indicators developed to date. We provide the description of each indicator and discuss its advantages and limitations, as well as points that need to be considered when choosing an indicator for a particular experiment. One chapter is devoted to the important discoveries that have been made by using genetically encoded redox indicators. Copyright © 2016 Elsevier Inc. All rights reserved.

Redox-active porous coordination polymer based on trinuclear pivalate: Temperature-dependent crystal rearrangement and redox-behavior

Energy Technology Data Exchange (ETDEWEB)

Lytvynenko, Anton S. [L.V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of Ukraine, Prospekt Nauki 31, Kiev 03028 (Ukraine); Kiskin, Mikhail A., E-mail: mkiskin@igic.ras.ru [N.S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Leninsky Prospect 31, GSP-1, 119991 Moscow (Russian Federation); Dorofeeva, Victoria N.; Mishura, Andrey M.; Titov, Vladimir E.; Kolotilov, Sergey V. [L.V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of Ukraine, Prospekt Nauki 31, Kiev 03028 (Ukraine); Eremenko, Igor L.; Novotortsev, Vladimir M. [N.S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Leninsky Prospect 31, GSP-1, 119991 Moscow (Russian Federation)

2015-03-15

Linking of trinuclear pivalate Fe{sub 2}NiO(Piv){sub 6} (Piv=O{sub 2}CC(CH{sub 3}){sub 3}) by 2,6-bis(4-pyridyl)-4-(1-naphthyl)pyridine (L) resulted in formation of 1D-porous coordination polymer Fe{sub 2}NiO(Piv){sub 6}(L)·Solv, which was characterized in two forms: DMSO solvate Fe{sub 2}NiO(Piv){sub 6}(L)(DMSO)·2.5DMSO (1) or water solvate Fe{sub 2}NiO(Piv){sub 6}(L)(H{sub 2}O) (2). X-ray structure of 1 was determined. Crystal lattice of 1 at 160 K contained open channels, filled by captured solvent, while temperature growth to 296 K led to the crystal lattice rearrangement and formation of closed voids. Redox-behavior of 2 was studied by cyclic voltammetry for a solid compound, deposited on glassy-carbon electrode. Redox-activity of L preserved upon incorporation in the coordination polymer. The presence of pores in desolvated sample Fe{sub 2}NiO(Piv){sub 6}(L) was confirmed by the measurements of N{sub 2} and H{sub 2} adsorption at 77 K. Potential barriers of the different molecules diffusion through pores were estimated by the means of molecular mechanics. - Graphical abstract: Redox-behavior of 1D-porous coordination polymer Fe{sub 2}NiO(Piv){sub 6}(L)(H{sub 2}O) was studied by cyclic voltammetry in thin film, deposited on glassy-carbon electrode. Redox-activity of L preserved upon incorporation in the coordination polymer. Potential barriers of different molecules diffusion through pores were estimated by the means of molecular mechanics. - Highlights: • Porous 1D coordination polymer was synthesized. • Temperature growth led to pores closing due to crystal lattice rearrangement. • Redox-activity of ligand preserved upon incorporation into coordination polymer. • Redox-properties of solid coordination polymer were studied in thin film. • Diffusion barriers were evaluated by molecular mechanics.

Hydrologic influence on redox dynamics in estuarine environments

Science.gov (United States)

Michael, H. A.; Kim, K. H.; Guimond, J. A.; Heiss, J.; Ullman, W. J.; Seyfferth, A.

2017-12-01

Redox conditions in coastal aquifers control reactions that impact nutrient cycling, contaminant release, and carbon budgets, with implications for water resources and ecosystem health. Hydrologic changes can shift redox boundaries and inputs of reactants, especially in dynamic coastal systems subject to fluctuations on tidal, lunar, and longer timescales. We present two examples of redox shifts in estuarine systems in Delaware, USA: a beach aquifer and a saltmarsh. Beach aquifers are biogeochemical hot spots due to mixing between fresh groundwater and infiltrating seawater. At Cape Henlopen, DE, geochemical measurements identified reactions in the intertidal aquifer that include cycling of carbon, nitrogen, iron, and sulfur. Measurements and modeling illustrate that redox potential as well as the locations of redox reactions shift on tidal to seasonal timescales and in response to changing beach and aquifer properties, impacting overall rates of reactions such as denitrification that reduces N loads to coastal waters. In the St. Jones National Estuarine Research Reserve, tidal fluctuations in channels cause periodic groundwater-surface water exchange, water table movement, and intermittent flooding that varies spatially across the saltmarsh. These changes create shifts in redox potential that are greatest near channels and in the top 20 cm of sediments. The magnitude of redox change depends on hydrologic setting (near channels or in marsh interior), hydrologic conditions (tidal stage, seasonal shifts), as well as prevalence of macropores created by crab burrows that change seasonally with crab activity. These shifts correspond to changes in porewater chemistry that have implications for nutrient cycling and carbon export to the ocean. Understanding hydrologic influence on redox geochemistry is critical for predicting how these systems and their ecosystem services may change in the future in response to anthropogenic and climate change.

Redox chemistry and natural organic matter (NOM): Geochemists' dream, analytical chemists' nightmare

Science.gov (United States)

Macalady, Donald L.; Walton-Day, Katherine

2011-01-01

Natural organic matter (NOM) is an inherently complex mixture of polyfunctional organic molecules. Because of their universality and chemical reversibility, oxidation/reductions (redox) reactions of NOM have an especially interesting and important role in geochemistry. Variabilities in NOM composition and chemistry make studies of its redox chemistry particularly challenging, and details of NOM-mediated redox reactions are only partially understood. This is in large part due to the analytical difficulties associated with NOM characterization and the wide range of reagents and experimental systems used to study NOM redox reactions. This chapter provides a summary of the ongoing efforts to provide a coherent comprehension of aqueous redox chemistry involving NOM and of techniques for chemical characterization of NOM. It also describes some attempts to confirm the roles of different structural moieties in redox reactions. In addition, we discuss some of the operational parameters used to describe NOM redox capacities and redox states, and describe nomenclature of NOM redox chemistry. Several relatively facile experimental methods applicable to predictions of the NOM redox activity and redox states of NOM samples are discussed, with special attention to the proposed use of fluorescence spectroscopy to predict relevant redox characteristics of NOM samples.

Activator Protein-1: redox switch controlling structure and DNA-binding

Energy Technology Data Exchange (ETDEWEB)

Yin, Zhou; Machius, Mischa; Nestler, Eric J.; Rudenko, Gabby (Texas-MED); (Icahn)

2017-09-07

The transcription factor, activator protein-1 (AP-1), binds to cognate DNA under redox control; yet, the underlying mechanism has remained enigmatic. A series of crystal structures of the AP-1 FosB/JunD bZIP domains reveal ordered DNA-binding regions in both FosB and JunD even in absence DNA. However, while JunD is competent to bind DNA, the FosB bZIP domain must undergo a large conformational rearrangement that is controlled by a ‘redox switch’ centered on an inter-molecular disulfide bond. Solution studies confirm that FosB/JunD cannot undergo structural transition and bind DNA when the redox-switch is in the ‘OFF’ state, and show that the mid-point redox potential of the redox switch affords it sensitivity to cellular redox homeostasis. The molecular and structural studies presented here thus reveal the mechanism underlying redox-regulation of AP-1 Fos/Jun transcription factors and provide structural insight for therapeutic interventions targeting AP-1 proteins.

Integrating a dual-silicon photoelectrochemical cell into a redox flow battery for unassisted photocharging.

Science.gov (United States)

Liao, Shichao; Zong, Xu; Seger, Brian; Pedersen, Thomas; Yao, Tingting; Ding, Chunmei; Shi, Jingying; Chen, Jian; Li, Can

2016-05-04

Solar rechargeable flow cells (SRFCs) provide an attractive approach for in situ capture and storage of intermittent solar energy via photoelectrochemical regeneration of discharged redox species for electricity generation. However, overall SFRC performance is restricted by inefficient photoelectrochemical reactions. Here we report an efficient SRFC based on a dual-silicon photoelectrochemical cell and a quinone/bromine redox flow battery for in situ solar energy conversion and storage. Using narrow bandgap silicon for efficient photon collection and fast redox couples for rapid interface charge injection, our device shows an optimal solar-to-chemical conversion efficiency of ∼5.9% and an overall photon-chemical-electricity energy conversion efficiency of ∼3.2%, which, to our knowledge, outperforms previously reported SRFCs. The proposed SRFC can be self-photocharged to 0.8 V and delivers a discharge capacity of 730 mAh l(-1). Our work may guide future designs for highly efficient solar rechargeable devices.

Redox proteomics of tomato in response to Pseudomonas syringae infection

Science.gov (United States)

Balmant, Kelly Mayrink; Parker, Jennifer; Yoo, Mi-Jeong; Zhu, Ning; Dufresne, Craig; Chen, Sixue

2015-01-01

Unlike mammals with adaptive immunity, plants rely on their innate immunity based on pattern-triggered immunity (PTI) and effector-triggered immunity (ETI) for pathogen defense. Reactive oxygen species, known to play crucial roles in PTI and ETI, can perturb cellular redox homeostasis and lead to changes of redox-sensitive proteins through modification of cysteine sulfhydryl groups. Although redox regulation of protein functions has emerged as an important mechanism in several biological processes, little is known about redox proteins and how they function in PTI and ETI. In this study, cysTMT proteomics technology was used to identify similarities and differences of protein redox modifications in tomato resistant (PtoR) and susceptible (prf3) genotypes in response to Pseudomonas syringae pv tomato (Pst) infection. In addition, the results of the redox changes were compared and corrected with the protein level changes. A total of 90 potential redox-regulated proteins were identified with functions in carbohydrate and energy metabolism, biosynthesis of cysteine, sucrose and brassinosteroid, cell wall biogenesis, polysaccharide/starch biosynthesis, cuticle development, lipid metabolism, proteolysis, tricarboxylic acid cycle, protein targeting to vacuole, and oxidation–reduction. This inventory of previously unknown protein redox switches in tomato pathogen defense lays a foundation for future research toward understanding the biological significance of protein redox modifications in plant defense responses. PMID:26504582

Redox-active labile iron in fortified flours from the Brazilian market Ferro lábil redox-ativo em farinhas fortificadas do mercado brasileiro

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Breno Pannia Espósito

2007-08-01

Full Text Available OBJECTIVE: To quantify the fraction of redox-active labile iron in iron-fortified flours acquired on the Brazilian market. METHODS: Samples of wheat flour, maize flour and breadcrumbs were extracted with buffers that mimic gastric juice, saliva and intestinal juice. Redox-active labile iron levels were assessed through the reaction of autoxidation of ascorbic acid catalyzed by iron in the presence of a fluorescence probe. RESULTS: Redox-active labile iron represents 1% to 9% of the total iron in the flour and breadcrumb samples, with the lowest values found under gastric juice conditions and the highest in the more alkaline media. Redox-active labile iron possibly arises from the decomposition of an iron-phytic acid complex. A positive correlation between redox-active labile iron and total iron was found in saline biomimetic fluids. CONCLUSION: Redox-active labile iron may be a risk factor for people with impaired antioxidant defenses, such as those who are atransferrinemic or iron overloaded (e.g. thalassemic. Total iron can be used to predict redox-active labile iron absorption at each stage of the gastrointestinal tract after ingestion of iron-fortified flours.OBJETIVO: Quantificar a porcentagem de ferro lábil redox ativo em farinhas fortificadas adquiridas no comércio popular. MÉTODOS: Amostras de farinha de trigo, fubá e rosca foram extraídas com tampões miméticos de suco gástrico, saliva e suco intestinal. Os níveis de ferro lábil redox ativo foram determinados por meio da reação de auto-oxidação do ácido ascórbico catalisada pelo ferro, em presença de uma sonda fluorimétrica. RESULTADOS: A fração de ferro lábil redox ativo representa entre 1% e 9% do ferro total nas farinhas estudadas, sendo os menores valores encontrados em condições miméticas do suco gástrico e os maiores nos meios mais alcalinos. Há indícios de que o ferro lábil redox ativo origina-se da decomposição de um complexo entre ferro e ácido f

Redox Couples with Unequal Diffusion Coefficients: Effect on Redox Cycling

NARCIS (Netherlands)

Mampallil Augustine, Dileep; Mathwig, Klaus; Kang, Shuo; Lemay, Serge Joseph Guy

2013-01-01

Redox cycling between two electrodes separated by a narrow gap allows dramatic amplification of the faradaic current. Unlike conventional electrochemistry at a single electrode, however, the mass-transport-limited current is controlled by the diffusion coefficient of both the reduced and oxidized

Polyarene mediators for mediated redox flow battery

Science.gov (United States)

Delnick, Frank M.; Ingersoll, David; Liang, Chengdu

2018-01-02

The fundamental charge storage mechanisms in a number of currently studied high energy redox couples are based on intercalation, conversion, or displacement reactions. With exception to certain metal-air chemistries, most often the active redox materials are stored physically in the electrochemical cell stack thereby lowering the practical gravimetric and volumetric energy density as a tradeoff to achieve reasonable power density. In a general embodiment, a mediated redox flow battery includes a series of secondary organic molecules that form highly reduced anionic radicals as reaction mediator pairs for the reduction and oxidation of primary high capacity redox species ex situ from the electrochemical cell stack. Arenes are reduced to stable anionic radicals that in turn reduce a primary anode to the charged state. The primary anode is then discharged using a second lower potential (more positive) arene. Compatible separators and solvents are also disclosed herein.

A multi-electron redox mediator for redox-targeting lithium-sulfur flow batteries

Science.gov (United States)

Li, Guochun; Yang, Liuqing; Jiang, Xi; Zhang, Tianran; Lin, Haibin; Yao, Qiaofeng; Lee, Jim Yang

2018-02-01

The lithium-sulfur flow battery (LSFB) is a new addition to the rechargeable lithium flow batteries (LFBs) where sulfur or a sulfur compound is used as the cathode material against the lithium anode. We report here our evaluation of an organic sulfide - dimethyl trisulfide (DMTS), as 1) a catholyte of a LFB and 2) a multi-electron redox mediator for discharging and charging a solid sulfur cathode without any conductive additives. The latter configuration is also known as the redox-targeting lithium-sulfur flow battery (RTLSFB). The LFB provides an initial discharge capacity of 131.5 mAh g-1DMTS (1.66 A h L-1), which decreases to 59 mAh g-1DMTS (0.75 A h L-1) after 40 cycles. The RTLSFB delivers a significantly higher application performance - initial discharge capacity of 1225.3 mAh g-1sulfur (3.83 A h L-1), for which 1030.9 mAh g-1sulfur (3.23 A h L-1) is still available after 40 cycles. The significant increase in the discharge and charge duration of the LFB after sulfur addition indicates that DMTS is better used as a redox mediator in a RTLSFB than as a catholyte in a LFB.

Redox phenomena controlling systems - a 7. framework programme collaborative project (2008-2012)

International Nuclear Information System (INIS)

2013-01-01

The objective of this EURATOM collaborative project is to understand Redox phenomena controlling the long-term release/retention of radionuclides (ReCosy programme) in nuclear waste disposal and to provide tools to apply the results to safety assessment. The project has been organized into 6 task forces: 1) implications of Redox for safety, 2) development of Redox determination methods, 3) Redox response of defined and near-natural systems, 4) Redox reactions of radionuclides, 5) Redox processes in radionuclide transport, and 6) Redox reactions affecting the spent fuel source-term

Designing medical technology for resilience: integrating health economics and human factors approaches.

Science.gov (United States)

Borsci, Simone; Uchegbu, Ijeoma; Buckle, Peter; Ni, Zhifang; Walne, Simon; Hanna, George B

2018-01-01

The slow adoption of innovation into healthcare calls into question the manner of evidence generation for medical technology. This paper identifies potential reasons for this including a lack of attention to human factors, poor evaluation of economic benefits, lack of understanding of the existing healthcare system and a failure to recognise the need to generate resilient products. Areas covered: Recognising a cross-disciplinary need to enhance evidence generation early in a technology's life cycle, the present paper proposes a new approach that integrates human factors and health economic evaluation as part of a wider systems approach to the design of technology. This approach (Human and Economic Resilience Design for Medical Technology or HERD MedTech) supports early stages of product development and is based on the recent experiences of the National Institute for Health Research London Diagnostic Evidence Co-operative in the UK. Expert commentary: HERD MedTech i) proposes a shift from design for usability to design for resilience, ii) aspires to reduce the need for service adaptation to technological constraints iii) ensures value of innovation at the time of product development, and iv) aims to stimulate discussion around the integration of pre- and post-market methods of assessment of medical technology.

Conductance Through a Redox System in the Coulomb Blockade Regime: Many-Particle Effects and Influence of Electronic Correlations

OpenAIRE

Tornow, Sabine; Zwicknagl, Gertrud

2009-01-01

We investigate the transport characteristics of a redox system weakly coupled to leads in the Coulomb blockade regime. The redox system comprises a donor and acceptor separated by an insulating bridge in a solution. It is modeled by a two-site extended Hubbard model which includes on-site and inter-site Coulomb interactions and the coupling to a bosonic bath. The current voltage characteristics is calculated at high temperatures using a rate equation approach. For high voltages exceeding the ...

A combined energetic and economic approach for the sustainable design of geothermal plants

International Nuclear Information System (INIS)

Franco, Alessandro; Vaccaro, Maurizio

2014-01-01

Highlights: • Exploitation of medium to low temperature geothermal sources: ORC power plants. • Integrated energetic and economic approach for the analysis of geothermal power plants. • A brief overview of the cost items of geothermal power plants. • Analysis of specific cost of geothermal power plants based on the method proposed. • Analysis of sustainability of geothermal energy systems based on resource durability. - Abstract: The perspectives of future development of geothermal power plants, mainly of small size for the exploitation of medium–low temperature reservoirs, are discussed and analyzed in the present paper. Even if there is a general interest in new power plants and investments in this sector are recognized, the new installations are reduced; the apparent advantage of null cost of the energy source is negatively balanced by the high drilling and installation costs. A key element for the design of a geothermal plant for medium temperature geothermal source is the definition of the power of the plant (size): this is important in order to define not only the economic plan but also the durability of the reservoir. Considering that it is not possible that the development of geothermal industry could be driven only by an economic perspective, the authors propose a method for joining energetic and economic approaches. The result of the combined energetic and economic analysis is interesting particularly in case of Organic Rankine Cycle (ORC) power plants in order to define a suitable and optimal size and to maximize the resource durability. The method is illustrated with reference to some particular case studies, showing that the sustainability of small size geothermal plants will be approached only if the research for more economic solutions will be combined with efforts in direction of efficiency increase

Imaging Mitochondrial Redox Potential and Its Possible Link to Tumor Metastatic Potential

Science.gov (United States)

Li, Lin Z.

2012-01-01

Cellular redox states can regulate cell metabolism, growth, differentiation, motility, apoptosis, signaling pathways, and gene expressions etc. Growing body of literature suggest importance of redox status for cancer progression. While most studies on redox state were done on cells and tissue lysates, it is important to understand the role of redox state in tissue in vivo/ex vivo and image its heterogeneity. Redox scanning is a clinically-translatable method for imaging tissue mitochondrial redox potential with a submillimeter resolution. Redox scanning data in mouse models of human cancers demonstrate a correlation between mitochondrial redox state and tumor metastatic potential. I will discuss the significance of this correlation and possible directions for future research. PMID:22895837

Characterization of redox proteins using electrochemical methods

NARCIS (Netherlands)

Verhagen, M.

1995-01-01

The use of electrochemical techniques in combination with proteins started approximately a decade ago and has since then developed into a powerfull technique for the study of small redox proteins. In addition to the determination of redox potentials, electrochemistry can be used to obtain

Chloroplasts as source and target of cellular redox regulation: a discussion on chloroplast redox signals in the context of plant physiology.

Science.gov (United States)

Baier, Margarete; Dietz, Karl-Josef

2005-06-01

During the evolution of plants, chloroplasts have lost the exclusive genetic control over redox regulation and antioxidant gene expression. Together with many other genes, all genes encoding antioxidant enzymes and enzymes involved in the biosynthesis of low molecular weight antioxidants were transferred to the nucleus. On the other hand, photosynthesis bears a high risk for photo-oxidative damage. Concomitantly, an intricate network for mutual regulation by anthero- and retrograde signals has emerged to co-ordinate the activities of the different genetic and metabolic compartments. A major focus of recent research in chloroplast regulation addressed the mechanisms of redox sensing and signal transmission, the identification of regulatory targets, and the understanding of adaptation mechanisms. In addition to redox signals communicated through signalling cascades also used in pathogen and wounding responses, specific chloroplast signals control nuclear gene expression. Signalling pathways are triggered by the redox state of the plastoquinone pool, the thioredoxin system, and the acceptor availability at photosystem I, in addition to control by oxolipins, tetrapyrroles, carbohydrates, and abscisic acid. The signalling function is discussed in the context of regulatory circuitries that control the expression of antioxidant enzymes and redox modulators, demonstrating the principal role of chloroplasts as the source and target of redox regulation.

Computational design of molecules for an all-quinone redox flow battery.

Science.gov (United States)

Er, Süleyman; Suh, Changwon; Marshak, Michael P; Aspuru-Guzik, Alán

2015-02-01

Inspired by the electron transfer properties of quinones in biological systems, we recently showed that quinones are also very promising electroactive materials for stationary energy storage applications. Due to the practically infinite chemical space of organic molecules, the discovery of additional quinones or other redox-active organic molecules for energy storage applications is an open field of inquiry. Here, we introduce a high-throughput computational screening approach that we applied to an accelerated study of a total of 1710 quinone (Q) and hydroquinone (QH 2 ) ( i.e. , two-electron two-proton) redox couples. We identified the promising candidates for both the negative and positive sides of organic-based aqueous flow batteries, thus enabling an all-quinone battery. To further aid the development of additional interesting electroactive small molecules we also provide emerging quantitative structure-property relationships.

Redox properties of structural Fe in clay minerals. 2. Electrochemical and spectroscopic characterization of electron transfer irreversibility in ferruginous smectite, SWa-1.

Science.gov (United States)

Gorski, Christopher A; Klüpfel, Laura; Voegelin, Andreas; Sander, Michael; Hofstetter, Thomas B

2012-09-04

Structural Fe in clay minerals is an important, albeit poorly characterized, redox-active phase found in many natural and engineered environments. This work develops an experimental approach to directly assess the redox properties of a natural Fe-bearing smectite (ferruginous smectite, SWa-1, 12.6 wt % Fe) with mediated electrochemical reduction (MER) and oxidation (MEO). By utilizing a suite of one-electron-transfer mediating compounds to facilitate electron transfer between structural Fe in SWa-1 and a working electrode, we show that the Fe2+/Fe3+ couple in SWa-1 is redox-active over a large range of potentials (from E(H) = -0.63 V to +0.61 V vs SHE). Electrochemical and spectroscopic analyses of SWa-1 samples that were subject to reduction and re-oxidation cycling revealed both reversible and irreversible structural Fe rearrangements that altered the observed apparent standard reduction potential (E(H)(ø)) of structural Fe. E(H)(ø)-values vary by as much as 0.56 V between SWa-1 samples with different redox histories. The wide range of E(H)-values over which SWa-1 is redox-active and redox history-dependent E(H)(ø)-values underscore the importance of Fe-bearing clay minerals as redox-active phases in a wide range of redox regimes.

Albumin-bound fatty acids but not albumin itself alter redox balance in tubular epithelial cells and induce a peroxide-mediated redox-sensitive apoptosis

Science.gov (United States)

Ruggiero, Christine; Elks, Carrie M.; Kruger, Claudia; Cleland, Ellen; Addison, Kaity; Noland, Robert C.

2014-01-01

Albuminuria is associated with metabolic syndrome and diabetes. It correlates with the progression of chronic kidney disease, particularly with tubular atrophy. The fatty acid load on albumin significantly increases in obesity, presenting a proinflammatory environment to the proximal tubules. However, little is known about changes in the redox milieu during fatty acid overload and how redox-sensitive mechanisms mediate cell death. Here, we show that albumin with fatty acid impurities or conjugated with palmitate but not albumin itself compromised mitochondrial and cell viability, membrane potential and respiration. Fatty acid overload led to a redox imbalance which deactivated the antioxidant protein peroxiredoxin 2 and caused a peroxide-mediated apoptosis through the redox-sensitive pJNK/caspase-3 pathway. Transfection of tubular cells with peroxiredoxin 2 was protective and mitigated apoptosis. Mitochondrial fatty acid entry and ceramide synthesis modulators suggested that mitochondrial β oxidation but not ceramide synthesis may modulate lipotoxic effects on tubular cell survival. These results suggest that albumin overloaded with fatty acids but not albumin itself changes the redox environment in the tubules, inducing a peroxide-mediated redox-sensitive apoptosis. Thus, mitigating circulating fatty acid levels may be an important factor in both preserving redox balance and preventing tubular cell damage in proteinuric diseases. PMID:24500687

The economics of gasification: a market-based approach

Energy Technology Data Exchange (ETDEWEB)

Abadie, L. M. [Bilbao Bizkaia Kutxa, Gran Via 30, 48009 Bilbao (Spain); Chamorro, J. M. [Departamento Fundamentos del Analisis Economico I, University of the Basque Country, Av. Lehendakari Aguirre 83, 48015 Bilbao (Spain)

2009-07-01

This paper deals with the economics of gasification facilities in general and Integrated Gasification Combined Cycle (IGCC) power plants in particular. Regarding the prospects of these systems, passing the technological test is one thing, passing the economic test can be quite another. In this respect, traditional valuations assume constant input and/or output prices. Since this is hardly realistic, we allow for uncertainty in prices. We naturally look at the markets where many of the products involved are regularly traded. Futures markets on commodities are particularly useful for valuing uncertain future cash flows. Thus, revenues and variable costs can be assessed by means of sound financial concepts and actual market data. On the other hand, these complex systems provide a number of flexibility options (e.g., to choose among several inputs, outputs, modes of operation, etc.). Typically, flexibility contributes significantly to the overall value of real assets. Indeed, maximization of the asset value requires the optimal exercise of any flexibility option available. Yet the economic value of flexibility is elusive, the more so under (price) uncertainty. And the right choice of input fuels and/or output products is a main concern for the facility managers. As a particular application, we deal with the valuation of input flexibility. We follow the Real Options approach. In addition to economic variables, we also address technical and environmental issues such as energy efficiency, utility performance characteristics and emissions (note that carbon constraints are looming). Lastly, a brief introduction to some stochastic processes suitable for valuation purposes is provided. (author)

The economics of gasification: a market-based approach

International Nuclear Information System (INIS)

Abadie, L. M.; Chamorro, J. M.

2009-01-01

This paper deals with the economics of gasification facilities in general and Integrated Gasification Combined Cycle (IGCC) power plants in particular. Regarding the prospects of these systems, passing the technological test is one thing, passing the economic test can be quite another. In this respect, traditional valuations assume constant input and/or output prices. Since this is hardly realistic, we allow for uncertainty in prices. We naturally look at the markets where many of the products involved are regularly traded. Futures markets on commodities are particularly useful for valuing uncertain future cash flows. Thus, revenues and variable costs can be assessed by means of sound financial concepts and actual market data. On the other hand, these complex systems provide a number of flexibility options (e.g., to choose among several inputs, outputs, modes of operation, etc.). Typically, flexibility contributes significantly to the overall value of real assets. Indeed, maximization of the asset value requires the optimal exercise of any flexibility option available. Yet the economic value of flexibility is elusive, the more so under (price) uncertainty. And the right choice of input fuels and/or output products is a main concern for the facility managers. As a particular application, we deal with the valuation of input flexibility. We follow the Real Options approach. In addition to economic variables, we also address technical and environmental issues such as energy efficiency, utility performance characteristics and emissions (note that carbon constraints are looming). Lastly, a brief introduction to some stochastic processes suitable for valuation purposes is provided. (author)

STATE AND ECONOMY IN BOURGEOISIES ECONOMIC THEORIES: A CRITICAL APPROACH

Directory of Open Access Journals (Sweden)

Verena Hernández-Pérez

2016-01-01

Full Text Available The issue of state-economy relationship has been present throughout the history of bourgeois economic thought. In the bourgeois liberal tradition the distinction between civil society and state has been presented as total and necessary, reserving to the first one the monopoly of economic activity, based on the principle of self-regulating market. From Keynes bourgeois economists were divided into two sides, one side those who still deny the state capacity to intervene right in the economy, and the other those who recognize the need for their participation. This paper proposes a critical approach to the major bourgeois theoretical positions on the relationship state-economy. 

A highly reversible anthraquinone-based anolyte for alkaline aqueous redox flow batteries

Science.gov (United States)

Cao, Jianyu; Tao, Meng; Chen, Hongping; Xu, Juan; Chen, Zhidong

2018-05-01

The development of electroactive organic materials for use in aqueous redox flow battery (RFB) electrolytes is highly attractive because of their structural flexibility, low cost and sustainability. Here, we report on a highly reversible anthraquinone-based anolyte (1,8-dihydroxyanthraquinone, 1,8-DHAQ) for alkaline aqueous RFB applications. Electrochemical measurements reveal the substituent position of hydroxyl groups for DHAQ isomers has a significant impact on the redox potential, electrochemical reversibility and water-solubility. 1,8-DHAQ shows the highest redox reversibility and rapidest mass diffusion among five isomeric DHAQs. The alkaline aqueous RFB using 1,8-DHAQ as the anolyte and potassium ferrocyanide as the catholyte yields open-circuit voltage approaching 1.1 V and current efficiency and capacity retention exceeding 99.3% and 99.88% per cycle, respectively. This aqueous RFB produces a maximum power density of 152 mW cm-2 at 100% SOC and 45 °C. Choline hydroxide was used as a hydrotropic agent to enhance the water-solubility of 1,8-DHAQ. 1,8-DHAQ has a maximum solubility of 3 M in 1 M KOH with 4 M choline hydroxide.

Time evolution of dissolved oxygen and redox conditions in a HLW repository

International Nuclear Information System (INIS)

Wersin, P.; Spahiu, K.; Bruno, J.

1994-02-01

The evolution of oxygen in a HLW repository has been studied using presently available geochemical background information. The important processes affecting oxygen migration in the near-field include diffusion and oxidation of pyrite and dissolved Fe(II). The evaluation of time scales of oxygen decrease is carried out with 1. an analytical approach involving the coupling of diffusion and chemical reaction, 2. a numerical geochemical approach involving the application of a newly developed diffusion-extended version of the STEADYQL code. Both approaches yield consistent rates of oxygen decrease and indicate that oxidation of pyrite impurities in the clay is the dominant process. The results obtained fRom geochemical modelling are interpreted in terms of evolution of redox conditions. Moreover, a sensitivity analysis of the major geochemical and physical parameters is performed. These results indicate that the uncertainties associated with reactive pyrite surface area impose the overall uncertainties of prediction of time scales. Thus, the obtained time of decrease to 1% of initial O 2 concentrations range between 7 and 290 years. The elapsed time at which the transition to anoxic conditions occurs is estimated to be within the same time range. Additional experimental information on redox sensitive impurities in the envisioned buffer and backfill material would further constrain the evaluated time scales. 41 refs

The measurement of reversible redox dependent post-translational modifications and their regulation of mitochondrial and skeletal muscle function

Directory of Open Access Journals (Sweden)

Philip A Kramer

2015-11-01

Full Text Available Mitochondrial oxidative stress is a common feature of skeletal myopathies across multiple conditions; however, the mechanism by which it contributes to skeletal muscle dysfunction remains controversial. Oxidative damage to proteins, lipids, and DNA has received the most attention, yet an important role for reversible redox post-translational modifications (PTMs in pathophysiology is emerging. The possibility that these PTMs can exert dynamic control of muscle function implicates them as a mechanism contributing to skeletal muscle dysfunction in chronic disease. Herein, we discuss the significance of thiol-based redox dependent modifications to mitochondrial, myofibrillar and excitation-contraction (EC coupling proteins with an emphasis on how these changes could alter skeletal muscle performance under chronically stressed conditions. A major barrier to a better mechanistic understanding of the role of reversible redox PTMs in muscle function is the technical challenges associated with accurately measuring the changes of site-specific redox PTMs. Here we will critically review current approaches with an emphasis on sample preparation artifacts, quantitation, and specificity. Despite these challenges, the ability to accurately quantify reversible redox PTMs is critical to understanding the mechanisms by which mitochondrial oxidative stress contributes to skeletal muscle dysfunction in chronic diseases.

The Measurement of Reversible Redox Dependent Post-translational Modifications and Their Regulation of Mitochondrial and Skeletal Muscle Function

Energy Technology Data Exchange (ETDEWEB)

Kramer, Philip A.; Duan, Jicheng; Qian, Wei-Jun; Marcinek, David J.

2015-11-25

Mitochondrial oxidative stress is a common feature of skeletal myopathies across multiple conditions; however, the mechanism by which it contributes to skeletal muscle dysfunction remains controversial. Oxidative damage to proteins, lipids, and DNA has received the most attention, yet an important role for reversible redox post-translational modifications (PTMs) in pathophysiology is emerging. The possibility that these PTMs can exert dynamic control of muscle function implicates them as a mechanism contributing to skeletal muscle dysfunction in chronic disease. Herein, we discuss the significance of thiol-based redox dependent modifications to mitochondrial, myofibrillar and excitation-contraction (EC) coupling proteins with an emphasis on how these changes could alter skeletal muscle performance under chronically stressed conditions. A major barrier to a better mechanistic understanding of the role of reversible redox PTMs in muscle function is the technical challenges associated with accurately measuring the changes of site-specific redox PTMs. Here we will critically review current approaches with an emphasis on sample preparation artifacts, quantitation, and specificity. Despite these challenges, the ability to accurately quantify reversible redox PTMs is critical to understanding the mechanisms by which mitochondrial oxidative stress contributes to skeletal muscle dysfunction in chronic diseases.

Activator Protein-1: redox switch controlling structure and DNA-binding.

Science.gov (United States)

Yin, Zhou; Machius, Mischa; Nestler, Eric J; Rudenko, Gabby

2017-11-02

The transcription factor, activator protein-1 (AP-1), binds to cognate DNA under redox control; yet, the underlying mechanism has remained enigmatic. A series of crystal structures of the AP-1 FosB/JunD bZIP domains reveal ordered DNA-binding regions in both FosB and JunD even in absence DNA. However, while JunD is competent to bind DNA, the FosB bZIP domain must undergo a large conformational rearrangement that is controlled by a 'redox switch' centered on an inter-molecular disulfide bond. Solution studies confirm that FosB/JunD cannot undergo structural transition and bind DNA when the redox-switch is in the 'OFF' state, and show that the mid-point redox potential of the redox switch affords it sensitivity to cellular redox homeostasis. The molecular and structural studies presented here thus reveal the mechanism underlying redox-regulation of AP-1 Fos/Jun transcription factors and provide structural insight for therapeutic interventions targeting AP-1 proteins. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

Redox-responsive theranostic nanoplatforms based on inorganic nanomaterials.

Science.gov (United States)

Han, Lu; Zhang, Xiao-Yong; Wang, Yu-Long; Li, Xi; Yang, Xiao-Hong; Huang, Min; Hu, Kun; Li, Lu-Hai; Wei, Yen

2017-08-10

Spurred on by advances in materials chemistry and nanotechnology, scientists have developed many novel nanopreparations for cancer diagnosis and therapy. To treat complex malignant tumors effectively, multifunctional nanomedicines with targeting ability, imaging properties and controlled drug release behavior should be designed and exploited. The therapeutic efficiency of loaded drugs can be dramatically improved using redox-responsive nanoplatforms which can sense the differences in the redox status of tumor tissues and healthy ones. Redox-sensitive nanocarriers can be constructed from both organic and inorganic nanomaterials; however, at present, drug delivery nanovectors progressively lean towards inorganic nanomaterials because of their facile synthesis/modification and their unique physicochemical properties. In this review, we focus specifically on the preparation and application of redox-sensitive nanosystems based on mesoporous silica nanoparticles (MSNs), carbon nanomaterials, magnetic nanoparticles, gold nanomaterials and other inorganic nanomaterials. We discuss relevant examples of redox-sensitive nanosystems in each category. Finally, we discuss current challenges and future strategies from the aspect of material design and practical application. Copyright © 2017 Elsevier B.V. All rights reserved.

Redox-active and Redox-silent Compounds: Synergistic Therapeutics in Cancer

Czech Academy of Sciences Publication Activity Database

Tomasetti, M.; Santarelli, L.; Alleva, R.; Dong, L.F.; Neužil, Jiří

2015-01-01

Roč. 22, č. 5 (2015), s. 552-568 ISSN 0929-8673 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:86652036 Keywords : Apoptosis * autophagy * redox-active agents Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.455, year: 2015

Carbon Redox-Polymer-Gel Hybrid Supercapacitors

Science.gov (United States)

Vlad, A.; Singh, N.; Melinte, S.; Gohy, J.-F.; Ajayan, P.M.

2016-01-01

Energy storage devices that provide high specific power without compromising on specific energy are highly desirable for many electric-powered applications. Here, we demonstrate that polymer organic radical gel materials support fast bulk-redox charge storage, commensurate to surface double layer ion exchange at carbon electrodes. When integrated with a carbon-based electrical double layer capacitor, nearly ideal electrode properties such as high electrical and ionic conductivity, fast bulk redox and surface charge storage as well as excellent cycling stability are attained. Such hybrid carbon redox-polymer-gel electrodes support unprecedented discharge rate of 1,000C with 50% of the nominal capacity delivered in less than 2 seconds. Devices made with such electrodes hold the potential for battery-scale energy storage while attaining supercapacitor-like power performances. PMID:26917470

Titanium nitride as an electrocatalyst for V(II)/V(III) redox couples in all-vanadium redox flow batteries

International Nuclear Information System (INIS)

Yang, Chunmei; Wang, Haining; Lu, Shanfu; Wu, Chunxiao; Liu, Yiyang; Tan, Qinglong; Liang, Dawei; Xiang, Yan

2015-01-01

Titanium nitride nanoparticles (TiN NPs) are proposed as a novel catalyst towards the V(II)/V(III) redox pair for the negative electrode in vanadium redox flow batteries (VRFB). Electrochemical properties of TiN NPs were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results show that TiN NPs demonstrate better electrochemical activity and reversibility for the processes of V(II)/V(III) redox couples as compared with the graphite NPs. TiN NPs facilitate the charge transfer in the V(II)/V(III) redox reaction. Performance of a VRFB using a TiN NPs coated carbon paper as a negative electrode is much higher than that of a VRFB with a raw carbon paper electrode. The columbic efficiency (CE), the voltage efficiency (VE) and the energy efficiency (EE) of the VRFB single cell at charge-discharge current density of 30 mA/cm 2 are 91.74%, 89.11% and 81.74%, respectively. During a 50 charge-discharge cycles test, the CE values of VRFB with TiN NPs consistently remain higher than 90%.

Extracellular redox state: refining the definition of oxidative stress in aging.

Science.gov (United States)

Jones, Dean P

2006-01-01

Oxidative stress in aging can result from an imbalance of prooxidants and antioxidants with excessive, destructive free radical chemistry. Thiol systems are important in the control of these processes, both by protecting against damage and serving in redox signaling mechanisms to sense danger and repair the damage. Studies by a number of research groups in collaboration with the Emory Clinical Biomarkers Laboratory show that the redox state of the central tissue antioxidant, glutathione (GSH), can be measured in human plasma and provides a quantitative systemic indicator of oxidative stress. Plasma GSH/GSSG redox in humans becomes oxidized with age, in response to chemotherapy, as a consequence of cigarette smoking, and in association with common age-related diseases (e.g., type 2 diabetes, cardiovascular disease). However, the GSH/GSSG redox is not equilibrated with the larger plasma cysteine/cystine (Cys/CySS) pool, and the Cys/CySS redox varies with age in a pattern that is distinct from that of GSH/GSSG redox. Furthermore, in vitro studies show that variation in Cys/CySS redox over the range found in vivo affects signaling pathways, which control cell proliferation and oxidant-induced apoptosis. The results point to the conclusion that free radical scavenging antioxidants are of increased importance when thiol/disulfide redox states are oxidized. Because thiol/disulfide redox states, per se, function in redox signaling and control as well as antioxidant protection, GSH/GSSG and Cys/CySS redox states may provide central parameters to link environmental influences and progression of changes associated with aging.

Kynurenine pathway metabolites and enzymes involved in redox reactions.

Science.gov (United States)

González Esquivel, D; Ramírez-Ortega, D; Pineda, B; Castro, N; Ríos, C; Pérez de la Cruz, V

2017-01-01

Oxido-reduction reactions are a fundamental part of the life due to support many vital biological processes as cellular respiration and glucose oxidation. In the redox reactions, one substance transfers one or more electrons to another substance. An important electron carrier is the coenzyme NAD + , which is involved in many metabolic pathways. De novo biosynthesis of NAD + is through the kynurenine pathway, the major route of tryptophan catabolism, which is sensitive to redox environment and produces metabolites with redox capacity, able to alter biological functions that are controlled by redox-responsive signaling pathways. Kynurenine pathway metabolites have been implicated in the physiology process and in the physiopathology of many diseases; processes that also share others factors as dysregulation of calcium homeostasis, mitochondrial dysfunction, oxidative stress, inflammation and cell death, which impact the redox environment. This review examines in detail the available evidence in which kynurenine pathway metabolites participate in redox reactions and their effect on cellular redox homeostasis, since the knowledge of the main factors and mechanisms that lead to cell death in many neurodegenative disorders and other pathologies, such as mitochondrial dysfunction, oxidative stress and kynurenines imbalance, will allow to develop therapies using them as targets. This article is part of the Special Issue entitled 'The Kynurenine Pathway in Health and Disease'. Copyright © 2016 Elsevier Ltd. All rights reserved.

Impact on the Fe redox cycling of organic ligands released by Synechococcus PCC 7002, under different iron fertilization scenarios. Modeling approach

Science.gov (United States)

Samperio-Ramos, Guillermo; González-Dávila, Melchor; Santana-Casiano, J. Magdalena

2018-06-01

The kinetics of Fe redox transformations are of crucial importance in determining the bioavailability of iron, due to inorganic Fe(II) and Fe weakly organic complexes being the most easily assimilated species by phytoplankton. The role played by the natural organic ligands excreted by the cyanobacteria Synecococcus PCC 7002 on the iron redox chemistry was studied at different stages of growth, considering changes in the organic exudation of the cyanobacteria, associated with growth under two different scenarios of iron availability. The oxidation/reduction processes of iron were studied at nanomolar levels and under different physicochemical conditions of pH (7.2- 8.2), temperature (5- 35 °C) and salinity (10- 37). The presence of natural organic exudates of Synechococcus affected the redox behavior of iron. A pH-dependent and photo-induced Fe(III) reduction process was detected in the presence of exudates produced under Fe-Low conditions. Photolytic reactions also modified the reactivity of those exudates with respect to Fe(II), increasing its lifetime in seawater. Without light mediated processes, organic ligands excreted under iron deficient conditions intensified the Fe(II) oxidation at pH redox constants between iron and the major ligands present in solution. Two organic type ligands for the exudates of Synechococcus PCC 7002, with different iron-chelation properties were included in the model. The Fe(II) speciation was radically affected when organic ligands were considered. The individual contributions to the overall Fe(II) oxidation rate demonstrated that these organic ligands played a key role in the oxidation process, although their contributions were dependent on the prescribed iron conditions. The study, therefore, suggests that the variability in the composition and nature of organic exudates released, due to iron availability conditions, might determine the redox behaviour of iron in seawater.

Accelerated redox reaction between chromate and phenolic pollutants during freezing

Energy Technology Data Exchange (ETDEWEB)

Ju, Jinjung; Kim, Jaesung [Department of Environmental Sciences and Biotechnology, Hallym University, Chuncheon, Gangwon-do 24252 (Korea, Republic of); Vetráková, Ľubica [Department of Chemistry and Research Centre for Toxic Compounds in the Environment (RECETOX), Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno (Czech Republic); Seo, Jiwon [School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919 (Korea, Republic of); Heger, Dominik [Department of Chemistry and Research Centre for Toxic Compounds in the Environment (RECETOX), Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno (Czech Republic); Lee, Changha [School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919 (Korea, Republic of); Yoon, Ho-Il [Korea Polar Research Institute (KOPRI), Incheon 21990 (Korea, Republic of); Kim, Kitae, E-mail: ktkim@kopri.re.kr [Korea Polar Research Institute (KOPRI), Incheon 21990 (Korea, Republic of); Kim, Jungwon, E-mail: jwk@hallym.ac.kr [Department of Environmental Sciences and Biotechnology, Hallym University, Chuncheon, Gangwon-do 24252 (Korea, Republic of)

2017-05-05

Highlights: • Redox conversion of 4-CP/Cr(VI) was significantly accelerated during freezing. • Accelerated redox conversion in ice is ascribed to the freeze concentration effect. • 4-CP, Cr(VI), and protons are concentrated in the liquid brine by freezing. • Redox conversions of various phenolic pollutants/Cr(VI) were significant in ice. • Freezing-accelerated redox conversion was observed in real polluted water. - Abstract: The redox reaction between 4-chlorophenol (4-CP) and chromate (Cr(VI)) (i.e., the simultaneous oxidation of 4-CP by Cr(VI) and reduction of Cr(VI) by 4-CP) in ice (i.e., at −20 °C) was compared with the corresponding reaction in water (i.e., at 25 °C). The redox conversion of 4-CP/Cr(VI), which was negligible in water, was significantly accelerated in ice. This accelerated redox conversion of 4-CP/Cr(VI) in ice is ascribed to the freeze concentration effect occurring during freezing, which excludes solutes (i.e., 4-CP and Cr(VI)) and protons from the ice crystals and subsequently concentrates them in the liquid brine. The concentrations of Cr(VI) and protons in the liquid brine were confirmed by measuring the optical image and the UV–vis absorption spectra of cresol red (CR) as a pH indicator of frozen solution. The redox conversion of 4-CP/Cr(VI) was observed in water when the concentrations of 4-CP/protons or Cr(VI)/protons increased by 100/1000-fold. These results corroborate the freeze concentration effect as the reason for the accelerated redox conversion of 4-CP/Cr(VI) in ice. The redox conversion of various phenolic pollutants/Cr(VI) and 4-CP/Cr(VI) in real wastewater was successfully achieved in ice, which verifies the environmental relevance and importance of freezing-accelerated redox conversion of phenolic pollutants/Cr(VI) in cold regions.

Accelerated redox reaction between chromate and phenolic pollutants during freezing

International Nuclear Information System (INIS)

Ju, Jinjung; Kim, Jaesung; Vetráková, Ľubica; Seo, Jiwon; Heger, Dominik; Lee, Changha; Yoon, Ho-Il; Kim, Kitae; Kim, Jungwon

2017-01-01

Highlights: • Redox conversion of 4-CP/Cr(VI) was significantly accelerated during freezing. • Accelerated redox conversion in ice is ascribed to the freeze concentration effect. • 4-CP, Cr(VI), and protons are concentrated in the liquid brine by freezing. • Redox conversions of various phenolic pollutants/Cr(VI) were significant in ice. • Freezing-accelerated redox conversion was observed in real polluted water. - Abstract: The redox reaction between 4-chlorophenol (4-CP) and chromate (Cr(VI)) (i.e., the simultaneous oxidation of 4-CP by Cr(VI) and reduction of Cr(VI) by 4-CP) in ice (i.e., at −20 °C) was compared with the corresponding reaction in water (i.e., at 25 °C). The redox conversion of 4-CP/Cr(VI), which was negligible in water, was significantly accelerated in ice. This accelerated redox conversion of 4-CP/Cr(VI) in ice is ascribed to the freeze concentration effect occurring during freezing, which excludes solutes (i.e., 4-CP and Cr(VI)) and protons from the ice crystals and subsequently concentrates them in the liquid brine. The concentrations of Cr(VI) and protons in the liquid brine were confirmed by measuring the optical image and the UV–vis absorption spectra of cresol red (CR) as a pH indicator of frozen solution. The redox conversion of 4-CP/Cr(VI) was observed in water when the concentrations of 4-CP/protons or Cr(VI)/protons increased by 100/1000-fold. These results corroborate the freeze concentration effect as the reason for the accelerated redox conversion of 4-CP/Cr(VI) in ice. The redox conversion of various phenolic pollutants/Cr(VI) and 4-CP/Cr(VI) in real wastewater was successfully achieved in ice, which verifies the environmental relevance and importance of freezing-accelerated redox conversion of phenolic pollutants/Cr(VI) in cold regions.

Comparing Conventional Bank Credit Vis A Vis Shariah Bank Musharakah: Experimental Economic Approach

Directory of Open Access Journals (Sweden)

Muhamad Abduh

2008-01-01

Full Text Available Central Bank of Indonesia with dual banking system – i.e Shariah and Conventional Bank – keep on developing system that considered as an answer to generate the national economic growth. One of the banking activities that emphasized by the Central Bank of Indonesia is fund distribution through either conventional bank credit or shariah bank fi nancing. Having the Experimental Economic Approach based on Induced Value Theory and employing ANOVA, this paper found that shariah bank musharakah fi nancing system would come up with higher profi t opportunity compare to conventional credit system. One main reason is that musharakah fi nancing in shariah bank applies profi t and lost sharing (PLS scheme so that will not be a burden to the customer when he fi nd low profi t.Keywords: Credit Loan, Musharakah Financing, Induced Value Theory, Experimental Economic Approach, Analysis of Variance (ANOVA.

A way to limit the corrosion in the Molten Salt Reactor concept: the salt redox potential control

International Nuclear Information System (INIS)

Gibilaro, M.; Massot, L.; Chamelot, P.

2015-01-01

The possibility of controlling the salt redox potential thanks to a redox buffer in the Molten Salt Fast Reactor was investigated, the goal was to limit the oxidation of the reactor structural material. Tests were performed in LiF-CaF 2 at 850 °C on two different redox couples to fix the salt potential, Eu(III)/Eu(II) and U(IV)/U(III), where the first one was used as inactive system to validate the methodology to be applied on the uranium system. A metallic reducing agent (Gd plate for Eu, and U plate for U system) was inserted in the salt, leading to a spontaneous reaction: Eu(III) and U(IV) were then reduced. Eu(III) was fully converted into Eu(II) with metallic Gd, validating the approach. On the U system, the U(IV)/U(III) ratio has to be set between 10 and 100 to limit the core material oxidation: addition of metallic U decreased the concentration ratio from the infinite to 1, showing the feasibility of the salt redox potential control with the U system

Organic non-aqueous cation-based redox flow batteries

Science.gov (United States)

Zhang, Lu; Huang, Jinhua; Burrell, Anthony

2018-05-08

The present invention provides a non-aqueous redox flow battery comprising a negative electrode immersed in a non-aqueous liquid negative electrolyte, a positive electrode immersed in a non-aqueous liquid positive electrolyte, and a cation-permeable separator (e.g., a porous membrane, film, sheet, or panel) between the negative electrolyte from the positive electrolyte. During charging and discharging, the electrolytes are circulated over their respective electrodes. The electrolytes each comprise an electrolyte salt (e.g., a lithium or sodium salt), a transition-metal free redox reactant, and optionally an electrochemically stable organic solvent. Each redox reactant is selected from an organic compound comprising a conjugated unsaturated moiety, a boron cluster compound, and a combination thereof. The organic redox reactant of the positive electrolyte comprises a tetrafluorohydroquinone ether compound or a tetrafluorocatechol ether compound.

Redox shuttles for overcharge protection of lithium batteries

Science.gov (United States)

Amine, Khalil; Chen, Zonghai; Wang, Qingzheng

2010-12-14

The present invention is generally related to electrolytes containing novel redox shuttles for overcharge protection of lithium-ion batteries. The redox shuttles are capable of thousands hours of overcharge tolerance and have a redox potential at about 3-5.5 V vs. Li and particularly about 4.4-4.8 V vs. Li. Accordingly, in one aspect the invention provides electrolytes comprising an alkali metal salt; a polar aprotic solvent; and a redox shuttle additive that is an aromatic compound having at least one aromatic ring with four or more electronegative substituents, two or more oxygen atoms bonded to the aromatic ring, and no hydrogen atoms bonded to the aromatic ring; and wherein the electrolyte solution is substantially non-aqueous. Further there are provided electrochemical devices employing the electrolyte and methods of making the electrolyte.

Approach and development strategy for an agent-based model of economic confidence.

Energy Technology Data Exchange (ETDEWEB)

Sprigg, James A.; Pryor, Richard J.; Jorgensen, Craig Reed

2004-08-01

We are extending the existing features of Aspen, a powerful economic modeling tool, and introducing new features to simulate the role of confidence in economic activity. The new model is built from a collection of autonomous agents that represent households, firms, and other relevant entities like financial exchanges and governmental authorities. We simultaneously model several interrelated markets, including those for labor, products, stocks, and bonds. We also model economic tradeoffs, such as decisions of households and firms regarding spending, savings, and investment. In this paper, we review some of the basic principles and model components and describe our approach and development strategy for emulating consumer, investor, and business confidence. The model of confidence is explored within the context of economic disruptions, such as those resulting from disasters or terrorist events.

Traditional vs. Modern Approaches in Business English Teaching in the Economic Field

OpenAIRE

Adriana Teodorescu

2013-01-01

This paper aims to examine different techniques and approaches used in teaching and learning business English in the economic field. Besides applying the already well-known methods used in second language acquisition, we also tried to incorporate computer-mediated communication into the communicative approach. At all times, the choice of the methods and approaches used in teaching business English has focused on our students' needs in their vocation or job. We worked with two groups of studen...

Modeling the economic impact of medication adherence in type 2 diabetes: a theoretical approach.

Science.gov (United States)

Cobden, David S; Niessen, Louis W; Rutten, Frans Fh; Redekop, W Ken

2010-09-07

While strong correlations exist between medication adherence and health economic outcomes in type 2 diabetes, current economic analyses do not adequately consider them. We propose a new approach to incorporate adherence in cost-effectiveness analysis. We describe a theoretical approach to incorporating the effect of adherence when estimating the long-term costs and effectiveness of an antidiabetic medication. This approach was applied in a Markov model which includes common diabetic health states. We compared two treatments using hypothetical patient cohorts: injectable insulin (IDM) and oral (OAD) medications. Two analyses were performed, one which ignored adherence (analysis 1) and one which incorporated it (analysis 2). Results from the two analyses were then compared to explore the extent to which adherence may impact incremental cost-effectiveness ratios. In both analyses, IDM was more costly and more effective than OAD. When adherence was ignored, IDM generated an incremental cost-effectiveness of $12,097 per quality-adjusted life-year (QALY) gained versus OAD. Incorporation of adherence resulted in a slightly higher ratio ($16,241/QALY). This increase was primarily due to better adherence with OAD than with IDM, and the higher direct medical costs for IDM. Incorporating medication adherence into economic analyses can meaningfully influence the estimated cost-effectiveness of type 2 diabetes treatments, and should therefore be considered in health care decision-making. Future work on the impact of adherence on health economic outcomes, and validation of different approaches to modeling adherence, is warranted.

De Novo Construction of Redox Active Proteins.

Science.gov (United States)

Moser, C C; Sheehan, M M; Ennist, N M; Kodali, G; Bialas, C; Englander, M T; Discher, B M; Dutton, P L

2016-01-01

Relatively simple principles can be used to plan and construct de novo proteins that bind redox cofactors and participate in a range of electron-transfer reactions analogous to those seen in natural oxidoreductase proteins. These designed redox proteins are called maquettes. Hydrophobic/hydrophilic binary patterning of heptad repeats of amino acids linked together in a single-chain self-assemble into 4-alpha-helix bundles. These bundles form a robust and adaptable frame for uncovering the default properties of protein embedded cofactors independent of the complexities introduced by generations of natural selection and allow us to better understand what factors can be exploited by man or nature to manipulate the physical chemical properties of these cofactors. Anchoring of redox cofactors such as hemes, light active tetrapyrroles, FeS clusters, and flavins by His and Cys residues allow cofactors to be placed at positions in which electron-tunneling rates between cofactors within or between proteins can be predicted in advance. The modularity of heptad repeat designs facilitates the construction of electron-transfer chains and novel combinations of redox cofactors and new redox cofactor assisted functions. Developing de novo designs that can support cofactor incorporation upon expression in a cell is needed to support a synthetic biology advance that integrates with natural bioenergetic pathways. © 2016 Elsevier Inc. All rights reserved.

Integrating a redox-coupled dye-sensitized photoelectrode into a lithium-oxygen battery for photoassisted charging.

Science.gov (United States)

Yu, Mingzhe; Ren, Xiaodi; Ma, Lu; Wu, Yiying

2014-10-03

With a high theoretical specific energy, the non-aqueous rechargeable lithium-oxygen battery is a promising next-generation energy storage technique. However, the large charging overpotential remains a challenge due to the difficulty in electrochemically oxidizing the insulating lithium peroxide. Recently, a redox shuttle has been introduced into the electrolyte to chemically oxidize lithium peroxide. Here, we report the use of a triiodide/iodide redox shuttle to couple a built-in dye-sensitized titanium dioxide photoelectrode with the oxygen electrode for the photoassisted charging of a lithium-oxygen battery. On charging under illumination, triiodide ions are generated on the photoelectrode, and subsequently oxidize lithium peroxide. Due to the contribution of the photovoltage, the charging overpotential is greatly reduced. The use of a redox shuttle to couple a photoelectrode and an oxygen electrode offers a unique strategy to address the overpotential issue of non-aqueous lithium-oxygen batteries and also a distinct approach for integrating solar cells and batteries.

Dimensional behavior of Ni-YSZ composites during redox cycling

DEFF Research Database (Denmark)

Pihlatie, Mikko; Kaiser, Andreas; Larsen, Peter Halvor

2009-01-01

The dimensional behavior of Ni-yttria-stabilized zirconia (YSZ) cermets during redox cycling was tested in dilatometry within the temperature range 600-1000 degrees C. The effect Of humidity oil redox stability was investigated at intermediate and low temperatures. We show that both the sintering...... of nickel depending on temperature of the initial reduction and the operating conditions, and the temperature of reoxidation are very important for the size of the dimensional change. Cumulative redox strain (CRS) is shown to be correlated with temperature. Measured maximum CRS after three redox cycles...... varies within 0.25-3.2% dL/L in dry gas and respective temperature range of 600-1000 degrees C. A high degree of redox reversibility was reached at low temperature. however. reversibility is lost at elevated temperatures. We found that at 850 degrees C, 6% steam and a very high p(H2O)/p(H2) ratio...

NAD(H) and NADP(H) Redox Couples and Cellular Energy Metabolism.

Science.gov (United States)

Xiao, Wusheng; Wang, Rui-Sheng; Handy, Diane E; Loscalzo, Joseph

2018-01-20

The nicotinamide adenine dinucleotide (NAD + )/reduced NAD + (NADH) and NADP + /reduced NADP + (NADPH) redox couples are essential for maintaining cellular redox homeostasis and for modulating numerous biological events, including cellular metabolism. Deficiency or imbalance of these two redox couples has been associated with many pathological disorders. Recent Advances: Newly identified biosynthetic enzymes and newly developed genetically encoded biosensors enable us to understand better how cells maintain compartmentalized NAD(H) and NADP(H) pools. The concept of redox stress (oxidative and reductive stress) reflected by changes in NAD(H)/NADP(H) has increasingly gained attention. The emerging roles of NAD + -consuming proteins in regulating cellular redox and metabolic homeostasis are active research topics. The biosynthesis and distribution of cellular NAD(H) and NADP(H) are highly compartmentalized. It is critical to understand how cells maintain the steady levels of these redox couple pools to ensure their normal functions and simultaneously avoid inducing redox stress. In addition, it is essential to understand how NAD(H)- and NADP(H)-utilizing enzymes interact with other signaling pathways, such as those regulated by hypoxia-inducible factor, to maintain cellular redox homeostasis and energy metabolism. Additional studies are needed to investigate the inter-relationships among compartmentalized NAD(H)/NADP(H) pools and how these two dinucleotide redox couples collaboratively regulate cellular redox states and cellular metabolism under normal and pathological conditions. Furthermore, recent studies suggest the utility of using pharmacological interventions or nutrient-based bioactive NAD + precursors as therapeutic interventions for metabolic diseases. Thus, a better understanding of the cellular functions of NAD(H) and NADP(H) may facilitate efforts to address a host of pathological disorders effectively. Antioxid. Redox Signal. 28, 251-272.

Pattern-oriented Agent-based Monte Carlo simulation of Cellular Redox Environment

DEFF Research Database (Denmark)

Tang, Jiaowei; Holcombe, Mike; Boonen, Harrie C.M.

/CYSS) and mitochondrial redox couples. Evidence suggests that both intracellular and extracellular redox can affect overall cell redox state. How redox is communicated between extracellular and intracellular environments is still a matter of debate. Some researchers conclude based on experimental data...... cells. Biochimica Et Biophysica Acta-General Subjects, 2008. 1780(11): p. 1271-1290. 5. Jones, D.P., Redox sensing: orthogonal control in cell cycle and apoptosis signalling. J Intern Med, 2010. 268(5): p. 432-48. 6. Pogson, M., et al., Formal agent-based modelling of intracellular chemical interactions...

Modeling the economic impact of medication adherence in type 2 diabetes: a theoretical approach

Directory of Open Access Journals (Sweden)

David S Cobden

2010-08-01

Full Text Available David S Cobden1, Louis W Niessen2, Frans FH Rutten1, W Ken Redekop11Department of Health Policy and Management, Section of Health Economics – Medical Technology Assessment (HE-MTA, Erasmus MC, Erasmus University Rotterdam, The Netherlands; 2Department of International Health, Johns Hopkins University School of Public Health, Johns Hopkins Medical Institutions, Baltimore, MD, USAAims: While strong correlations exist between medication adherence and health economic outcomes in type 2 diabetes, current economic analyses do not adequately consider them. We propose a new approach to incorporate adherence in cost-effectiveness analysis.Methods: We describe a theoretical approach to incorporating the effect of adherence when estimating the long-term costs and effectiveness of an antidiabetic medication. This approach was applied in a Markov model which includes common diabetic health states. We compared two treatments using hypothetical patient cohorts: injectable insulin (IDM and oral (OAD medications. Two analyses were performed, one which ignored adherence (analysis 1 and one which incorporated it (analysis 2. Results from the two analyses were then compared to explore the extent to which adherence may impact incremental cost-effectiveness ratios.Results: In both analyses, IDM was more costly and more effective than OAD. When adherence was ignored, IDM generated an incremental cost-effectiveness of $12,097 per quality-adjusted life-year (QALY gained versus OAD. Incorporation of adherence resulted in a slightly higher ratio ($16,241/QALY. This increase was primarily due to better adherence with OAD than with IDM, and the higher direct medical costs for IDM.Conclusions: Incorporating medication adherence into economic analyses can meaningfully influence the estimated cost-effectiveness of type 2 diabetes treatments, and should therefore be ­considered in health care decision-making. Future work on the impact of adherence on health ­economic

Approaches to Identification of Institutions in Institutional Economics

Directory of Open Access Journals (Sweden)

Igor M. Shiriaev

2017-03-01

Full Text Available The paper deals with the methodology for identification of institutions from institutional economics perspective. The differences between the perspectives provided by old and new institutional economics are highlighted. These differences are interpreted in the context of compared pragmatist and postpositivist methodologies. This paper applies to the post-positivist approach to the identification of institutions. One example of institution is provided by power-property institution. Identification of this institution in the historical and economic research is based on several theoretical generalizations and supported by array of historical facts. Another example is provided by identification of institution and institutional change in higher education based on discourse analysis and interviews with the main actors. In this paper, the regulatory institutions of higher education are analyzed as well. The concept of power-property institution is extended to the higher education by proposing hypotheses on the functioning of state governing-regulating institution in this sphere. This institution prescribes the actors to behave in accordance with the objectives of public policy, which can only be implemented in the form of bureaucratization of higher education. The paper describes the behavioral regularity generated by an identified institution. Functioning of the governing-regulating institution in higher education is illustrated by examples of behavioral regularities emerging from activities in accordance with this institution. The paper also shows the possibility of falsification of proposed hypothesis.

Thioredoxin-dependent Redox Regulation of Chloroplastic Phosphoglycerate Kinase from Chlamydomonas reinhardtii*

Science.gov (United States)

Morisse, Samuel; Michelet, Laure; Bedhomme, Mariette; Marchand, Christophe H.; Calvaresi, Matteo; Trost, Paolo; Fermani, Simona; Zaffagnini, Mirko; Lemaire, Stéphane D.

2014-01-01

In photosynthetic organisms, thioredoxin-dependent redox regulation is a well established mechanism involved in the control of a large number of cellular processes, including the Calvin-Benson cycle. Indeed, 4 of 11 enzymes of this cycle are activated in the light through dithiol/disulfide interchanges controlled by chloroplastic thioredoxin. Recently, several proteomics-based approaches suggested that not only four but all enzymes of the Calvin-Benson cycle may withstand redox regulation. Here, we characterized the redox features of the Calvin-Benson enzyme phosphoglycerate kinase (PGK1) from the eukaryotic green alga Chlamydomonas reinhardtii, and we show that C. reinhardtii PGK1 (CrPGK1) activity is inhibited by the formation of a single regulatory disulfide bond with a low midpoint redox potential (−335 mV at pH 7.9). CrPGK1 oxidation was found to affect the turnover number without altering the affinity for substrates, whereas the enzyme activation appeared to be specifically controlled by f-type thioredoxin. Using a combination of site-directed mutagenesis, thiol titration, mass spectrometry analyses, and three-dimensional modeling, the regulatory disulfide bond was shown to involve the not strictly conserved Cys227 and Cys361. Based on molecular mechanics calculation, the formation of the disulfide is proposed to impose structural constraints in the C-terminal domain of the enzyme that may lower its catalytic efficiency. It is therefore concluded that CrPGK1 might constitute an additional light-modulated Calvin-Benson cycle enzyme with a low activity in the dark and a TRX-dependent activation in the light. These results are also discussed from an evolutionary point of view. PMID:25202015

Breast Cancer Redox Heterogeneity Detectable with Chemical Exchange Satruation Transfer (CEST) MRI

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Cai, Kejia; Xu, He N.; Singh, Anup; Moon, Lily; Haris, Mohammad; Reddy, Ravinder; Li, Lin

2014-01-01

Purpose Tissue redox state is an important mediator of various biological processes in health and diseases such as cancer. Previously, we discovered that the mitochondrial redox state of ex vivo tissues detected by redox scanning (an optical imaging method) revealed interesting tumor redox state heterogeneity that could differentiate tumor aggressiveness. Because the noninvasive chemical exchange saturation transfer (CEST) MRI can probe the proton transfer and generate contrasts from endogenous metabolites, we aim to investigate if the in vivo CEST contrast is sensitive to proton transfer of the redox reactions so as to reveal the tissue redox states in breast cancer animal models. Procedures CEST MRI has been employed to characterize tumor metabolic heterogeneity and correlated with the redox states measured by the redox scanning in two human breast cancer mouse xenograft models, MDA-MB-231 and MCF-7. The possible biological mechanism on the correlation between the two imaging modalities was further investigated by phantom studies where the reductants and the oxidants of the representative redox reactions were measured. Results The CEST contrast is found linearly correlated with NADH concentration and the NADH redox ratio with high statistical significance, where NADH is the reduced form of nicotinamide adenine dinucleotide. The phantom studies showed that the reductants of the redox reactions have more CEST contrast than the corresponding oxidants, indicating that higher CEST effect corresponds to the more reduced redox state. Conclusions This preliminary study suggests that CEST MRI, once calibrated, might provide a novel noninvasive imaging surrogate for the tissue redox state and a possible diagnostic biomarker for breast cancer in the clinic. PMID:24811957

Hydrogen peroxide and central redox theory for aerobic life: A tribute to Helmut Sies: Scout, trailblazer, and redox pioneer.

Science.gov (United States)

Jones, Dean P

2016-04-01

When Rafael Radi and I wrote about Helmut Sies for the Redox Pioneer series, I was disappointed that the Editor restricted us to the use of "Pioneer" in the title. My view is that Helmut was always ahead of the pioneers: He was a scout discovering paths for exploration and a trailblazer developing strategies and methods for discovery. I have known him for nearly 40 years and greatly enjoyed his collegiality as well as brilliance in scientific scholarship. He made monumental contributions to 20th century physiological chemistry beginning with his first measurement of H2O2 in rat liver. While continuous H2O2 production is dogma today, the concept of H2O2 production in mammalian tissues was largely buried for half a century. He continued this leadership in research on oxidative stress, GSH, selenium, and singlet oxygen, during the timeframe when physiological chemistry and biochemistry transitioned to contemporary 21st century systems biology. His impact has been extensive in medical and health sciences, especially in nutrition, aging, toxicology and cancer. I briefly summarize my interactions with Helmut, stressing our work together on the redox code, a set of principles to link mitochondrial respiration, bioenergetics, H2O2 metabolism, redox signaling and redox proteomics into central redox theory. Copyright © 2015 The Author. Published by Elsevier Inc. All rights reserved.

The Comprehensive Approach to Assessing the Economic Security of the Industry Sector in Conditions of Globalization

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Denysov Oleg Ye.

2018-01-01

Full Text Available The author carries out an empirical study of the level of economic security of the chemical industry sector of Ukraine in the direction of «production of polyvinyl chlorides». For this purpose the integral index of economic security has been calculated according to the model of functional-component blocks of economic security of sector, developed by the author. Application of this model allowed to research the algorithm of action of the model on the factual basis and to analyze the obtained indicators. This, in turn, made possible to draw a conclusion about the constructiveness and expediency of application of the model of basic functional-component blocks for calculating the level of economic security of the industry sector. With the help of this approach, with application of the complex, system-structural, dynamic and functional approaches, the level of economic security has been defined and the process of monitoring the status and level of economic security of the industry sector has been ensured.

Redox signaling in acute pancreatitis

Science.gov (United States)

Pérez, Salvador; Pereda, Javier; Sabater, Luis; Sastre, Juan

2015-01-01

Acute pancreatitis is an inflammatory process of the pancreatic gland that eventually may lead to a severe systemic inflammatory response. A key event in pancreatic damage is the intracellular activation of NF-κB and zymogens, involving also calcium, cathepsins, pH disorders, autophagy, and cell death, particularly necrosis. This review focuses on the new role of redox signaling in acute pancreatitis. Oxidative stress and redox status are involved in the onset of acute pancreatitis and also in the development of the systemic inflammatory response, being glutathione depletion, xanthine oxidase activation, and thiol oxidation in proteins critical features of the disease in the pancreas. On the other hand, the release of extracellular hemoglobin into the circulation from the ascitic fluid in severe necrotizing pancreatitis enhances lipid peroxidation in plasma and the inflammatory infiltrate into the lung and up-regulates the HIF–VEGF pathway, contributing to the systemic inflammatory response. Therefore, redox signaling and oxidative stress contribute to the local and systemic inflammatory response during acute pancreatitis. PMID:25778551

Redox signaling in acute pancreatitis

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Salvador Pérez

2015-08-01

Full Text Available Acute pancreatitis is an inflammatory process of the pancreatic gland that eventually may lead to a severe systemic inflammatory response. A key event in pancreatic damage is the intracellular activation of NF-κB and zymogens, involving also calcium, cathepsins, pH disorders, autophagy, and cell death, particularly necrosis. This review focuses on the new role of redox signaling in acute pancreatitis. Oxidative stress and redox status are involved in the onset of acute pancreatitis and also in the development of the systemic inflammatory response, being glutathione depletion, xanthine oxidase activation, and thiol oxidation in proteins critical features of the disease in the pancreas. On the other hand, the release of extracellular hemoglobin into the circulation from the ascitic fluid in severe necrotizing pancreatitis enhances lipid peroxidation in plasma and the inflammatory infiltrate into the lung and up-regulates the HIF–VEGF pathway, contributing to the systemic inflammatory response. Therefore, redox signaling and oxidative stress contribute to the local and systemic inflammatory response during acute pancreatitis.

Arteriovenous oscillations of the redox potential: Is the redox state influencing blood flow?

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Poznanski, Jaroslaw; Szczesny, Pawel; Pawlinski, Bartosz; Mazurek, Tomasz; Zielenkiewicz, Piotr; Gajewski, Zdzislaw; Paczek, Leszek

2017-09-01

Studies on the regulation of human blood flow revealed several modes of oscillations with frequencies ranging from 0.005 to 1 Hz. Several mechanisms were proposed that might influence these oscillations, such as the activity of vascular endothelium, the neurogenic activity of vessel wall, the intrinsic activity of vascular smooth muscle, respiration, and heartbeat. These studies relied typically on non-invasive techniques, for example, laser Doppler flowmetry. Oscillations of biochemical markers were rarely coupled to blood flow. The redox potential difference between the artery and the vein was measured by platinum electrodes placed in the parallel homonymous femoral artery and the femoral vein of ventilated anesthetized pigs. Continuous measurement at 5 Hz sampling rate using a digital nanovoltmeter revealed fluctuating signals with three basic modes of oscillations: ∼ 1, ∼ 0.1 and ∼ 0.01 Hz. These signals clearly overlap with reported modes of oscillations in blood flow, suggesting coupling of the redox potential and blood flow. The amplitude of the oscillations associated with heart action was significantly smaller than for the other two modes, despite the fact that heart action has the greatest influence on blood flow. This finding suggests that redox potential in blood might be not a derivative but either a mediator or an effector of the blood flow control system.

The developments and challenges of cerium half-cell in zinc–cerium redox flow battery for energy storage

International Nuclear Information System (INIS)

Xie, Zhipeng; Liu, Qingchao; Chang, Zhiwen; Zhang, Xinbo

2013-01-01

Zinc–cerium redox flow batteries (ZCBs) are emerging as a very promising new technology with the potential to store a large amount of energy economically and efficiently, thanking to its highest thermodynamic open-circuit cell voltage among all the currently studied aqueous redox flow batteries. However, there are numerous scientific and technical challenges that must be overcome if this alluring promise is to turn into reality, from designing the battery structure, to optimizing the electrolyte compositions and elucidating the complex chemical reactions that occur during charge and discharge. This review article is the first summary of the most significant developments and challenges of cerium half-cell and the current understanding of their chemistry. We are certain that this review will be of great interest to audience over a broad range, especially in fields of energy storage, electrochemistry, and chemical engineering

Biogeochemical Barriers: Redox Behavior of Metals and Metalloids

Science.gov (United States)

Redox conditions and pH are arguably the most important geochemical parameters that control contaminant transport and fate in groundwater systems. Oxidation-reduction (redox) reactions mediate the chemical behavior of both inorganic and organic chemical constituents by affecting...

Neuro-genetic hybrid approach for the solution of non-convex economic dispatch problem

International Nuclear Information System (INIS)

Malik, T.N.; Asar, A.U.

2009-01-01

ED (Economic Dispatch) is non-convex constrained optimization problem, and is used for both on line and offline studies in power system operation. Conventionally, it is solved as convex problem using optimization techniques by approximating generator input/output characteristic. Curves of monotonically increasing nature thus resulting in an inaccurate dispatch. The GA (Genetic Algorithm) has been used for the solution of this problem owing to its inherent ability to address the convex and non-convex problems equally. This approach brings the solution to the global minimum region of search space in a short time and then takes longer time to converge to near optimal results. GA based hybrid approaches are used to fine tune the near optimal results produced by GA. This paper proposes NGH (Neuro Genetic Hybrid) approach to solve the economic dispatch with valve point effect. The proposed approach combines the GA with the ANN (Artificial Neural Network) using SI (Swarm Intelligence) learning rule. The GA acts as a global optimizer and the neural network fine tunes the GA results to the desired targets. Three machines standard test system has been tested for validation of the approach. Comparing the results with GA and NGH model based on back-propagation learning, the proposed approach gives contrast improvements showing the promise of the approach. (author)

Redox Stable Anodes for Solid Oxide Fuel Cells

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Guoliang eXiao

2014-06-01

Full Text Available Solid oxide fuel cells (SOFCs can convert chemical energy from the fuel directly to electrical energy with high efficiency and fuel flexibility. Ni-based cermets have been the most widely adopted anode for SOFCs. However, the conventional Ni-based anode has low tolerance to sulfur-contamination, is vulnerable to deactivation by carbon build-up (coking from direct oxidation of hydrocarbon fuels, and suffers volume instability upon redox cycling. Among these limitations, the redox instability of the anode is particularly important and has been intensively studied since the SOFC anode may experience redox cycling during fuel cell operations even with the ideal pure hydrogen as the fuel. This review aims to highlight recent progresses on improving redox stability of the conventional Ni-based anode through microstructure optimization and exploration of alternative ceramic-based anode materials.

Thermo-Kinetic Investigation of Comparative Ligand Effect on Cysteine Iron Redox Reaction

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Masood Ahmad Rizvi

2015-03-01

Full Text Available Transition metal ions in their free state bring unwanted biological oxidations generating oxidative stress. The ligand modulated redox potential can be indispensable in prevention of such oxidative stress by blocking the redundant bio-redox reactions. In this study we investigated the comparative ligand effect on the thermo-kinetic aspects of biologically important cysteine iron (III redox reaction using spectrophotometric and potentiometric methods. The results were corroborated with the complexation effect on redox potential of iron(III-iron(II redox couple. The selected ligands were found to increase the rate of cysteine iron (III redox reaction in proportion to their stability of iron (II complex (EDTA < terpy < bipy < phen. A kinetic profile and the catalytic role of copper (II ions by means of redox shuttle mechanism for the cysteine iron (III redox reaction in presence of 1,10-phenanthroline (phen ligand is also reported.

Redox processes in radiation biology and cancer

International Nuclear Information System (INIS)

Greenstock, C.L.

1981-01-01

Free-radical intermediates, particularly the activated oxygen species OH, O - 2 , and 1 O 2 , are implicated in many types of radiation damage to biological systems. In addition, these same species may be formed, either directly or indirectly through biochemical redox reactions, in both essential and aberrant metabolic processes. Cell survival and adaptation to an environment containing ionizing radiation and other physical and chemical carcinogens ultimately depend upon the cell's ability to maintain optimal function in response to free-radical damage at the chemical level. Many of these feedback control mechanisms are redox controlled. Radiation chemical techniques using selective radical scavengers, such as product analysis and pulse radiolysis, enable us to generate, observe, and characterize individually the nature and reactivity of potentially damaging free radicals. From an analysis of the chemical kinetics of free-radical involvement in biological damage, redox mechanisms are proposed to describe the early processes of radiation damage, redox mechanisms are proposed to describe the early processes of radiation damage, its protection and sensitization, and the role of free radicals in radiation and chemical carcinogenesis

Differential alkylation-based redox proteomics - Lessons learnt

DEFF Research Database (Denmark)

Wojdyla, Katarzyna; Rogowska-Wrzesinska, Adelina

2015-01-01

Cysteine is one of the most reactive amino acids. This is due to the electronegativity of sulphur atom in the side chain of thiolate group. It results in cysteine being present in several distinct redox forms inside the cell. Amongst these, reversible oxidations, S-nitrosylation and S-sulfenylati......Cysteine is one of the most reactive amino acids. This is due to the electronegativity of sulphur atom in the side chain of thiolate group. It results in cysteine being present in several distinct redox forms inside the cell. Amongst these, reversible oxidations, S-nitrosylation and S......-sulfenylation are crucial mediators of intracellular redox signalling, with known associations to health and disease. Study of their functionalities has intensified thanks to the development of various analytical strategies, with particular contribution from differential alkylation-based proteomics methods. Presented here...... is a critical evaluation of differential alkylation-based strategies for the analysis of S-nitrosylation and S-sulfenylation. The aim is to assess the current status and to provide insights for future directions in the dynamically evolving field of redox proteomics. To achieve that we collected 35 original...

Development of redox stable, multifunctional substrates for anode supported SOFCS

DEFF Research Database (Denmark)

Sudireddy, Bhaskar Reddy; Foghmoes, Søren Preben Vagn; Ramos, Tania

2017-01-01

Redox stable solid oxide fuel cells are beneficial in many aspects such as tolerance against system failures e.g fuel cut off and emergency shut down, but also allow for higher fuel utilization, which increases efficiency. State-ofthe-art Ni-cermet based anodes suffer from microstructural changes...... with a multifunctional anode support, the development of a two layer fuel electrode based on a redox stable strontium titanate layer for the electrochemically active layer and a redox stable Ni-YSZ support was pursued. Half-cells with well adhearing strontium titante anode layers on stateof-the-art Ni-YSZ cermet...... supports have been achieved. Redox tolerance of the half-cell depends could be increased by optimizing the redox stability of the cermet support....

Redox chemistry of americium in nitric acid media

Energy Technology Data Exchange (ETDEWEB)

Picart, S.; Jobelin, I.; Armengol, G.; Adnet, JM

2004-07-01

The redox properties of the actinides are very important parameters for speciation studies and spent nuclear fuel reprocessing based on liquid-liquid extraction of actinides at different oxidation states (as in the Purex or Sesame process). They are also very useful for developing analytical tools including coulometry and redox titration. This study addressed the americium(IV)/americium(III) and americium(VI)/americium(V) redox couples, focusing on exhaustive acquisition of the thermodynamic and kinetic parameters of americium oxidation at an electrode in a complexing nitric acid medium. (authors)

Redox chemistry of americium in nitric acid media

International Nuclear Information System (INIS)

Picart, S.; Jobelin, I.; Armengol, G.; Adnet, JM.

2004-01-01

The redox properties of the actinides are very important parameters for speciation studies and spent nuclear fuel reprocessing based on liquid-liquid extraction of actinides at different oxidation states (as in the Purex or Sesame process). They are also very useful for developing analytical tools including coulometry and redox titration. This study addressed the americium(IV)/americium(III) and americium(VI)/americium(V) redox couples, focusing on exhaustive acquisition of the thermodynamic and kinetic parameters of americium oxidation at an electrode in a complexing nitric acid medium. (authors)

Redox modification of caveolar proteins in the cardiovascular system- role in cellular signalling and disease.

Science.gov (United States)

Bubb, Kristen J; Birgisdottir, Asa Birna; Tang, Owen; Hansen, Thomas; Figtree, Gemma A

2017-08-01

Rapid and coordinated release of a variety of reactive oxygen species (ROS) such as superoxide (O 2 .- ), hydrogen peroxide (H 2 O 2 ) and peroxynitrite, in specific microdomains, play a crucial role in cell signalling in the cardiovascular system. These reactions are mediated by reversible and functional modifications of a wide variety of key proteins. Dysregulation of this oxidative signalling occurs in almost all forms of cardiovascular disease (CVD), including at the very early phases. Despite the heavily publicized failure of "antioxidants" to improve CVD progression, pharmacotherapies such as those targeting the renin-angiotensin system, or statins, exert at least part of their large clinical benefit via modulating cellular redox signalling. Over 250 proteins, including receptors, ion channels and pumps, and signalling proteins are found in the caveolae. An increasing proportion of these are being recognized as redox regulated-proteins, that reside in the immediate vicinity of the two major cellular sources of ROS, nicotinamide adenine dinucleotide phosphate oxidase (Nox) and uncoupled endothelial nitric oxide synthase (eNOS). This review focuses on what is known about redox signalling within the caveolae, as well as endogenous protective mechanisms utilized by the cell, and new approaches to targeting dysregulated redox signalling in the caveolae as a therapeutic strategy in CVD. Copyright © 2017. Published by Elsevier Inc.

Metabolic and redox barriers in the skin exposed to drugs and xenobiotics.

Science.gov (United States)

Korkina, Liudmila

2016-01-01

Growing exposure of human skin to environmental and occupational hazards, to numerous skin care/beauty products, and to topical drugs led to a biomedical concern regarding sustainability of cutaneous chemical defence that is essential for protection against intoxication. Since skin is the largest extra-hepatic drug/xenobiotic metabolising organ where redox-dependent metabolic pathways prevail, in this review, publications on metabolic processes leading to redox imbalance (oxidative stress) and its autocrine/endocrine impact to cutaneous drug/xenobiotic metabolism were scrutinised. Chemical and photo-chemical skin barriers contain metabolic and redox compartments: their protective and homeostatic functions. The review will examine the striking similarity of adaptive responses to exogenous chemical/photo-chemical stressors and endogenous toxins in cutaneous metabolic and redox system; the role(s) of xenobiotics/drugs and phase II enzymes in the endogenous antioxidant defence and maintenance of redox balance; redox regulation of interactions between metabolic and inflammatory responses in skin cells; skin diseases sharing metabolic and redox problems (contact dermatitis, lupus erythematosus, and vitiligo) Due to exceptional the redox dependence of cutaneous metabolic pathways and interaction of redox active metabolites/exogenous antioxidants with drug/xenobiotic metabolism, metabolic tests of topical xenobiotics/drugs should be combined with appropriate redox analyses and performed on 3D human skin models.

New approaches to the design and economics of EHV transmission plant

CERN Document Server

Jones, Brian

1972-01-01

New Approaches to the Design and Economics of EHV Transmission Plant examines the limitations of EHV transmission plant. Analysis is also covered in the book to correct these limitations. The concept behind EHV is that allowable transfer of electricity is related to the square of the voltage. Factors such as the expense of supplying a certain volume of electricity over a given distance and creations of power stations are examined. The book provides economic studies of alternative design policies based on estimation of costs and benefits of the design parameters. The text also focuses on the pr

Effects of moisture content and redox potential on in situ K d values for radioiodine in soil

International Nuclear Information System (INIS)

Ashworth, D.J.; Shaw, G.

2006-01-01

The soil solid-liquid distribution coefficient (K d ) value is of great significance in understanding and modelling the environmental behaviour of soil contaminants. For many years, the batch sorption technique has been used for the determination of such values. Here, we propose an alternative 'mini-column' approach in which somewhat more realistic soil conditions are maintained. In particular, this approach allows for determination of radionuclide K d values under realistic soil moisture contents and in a system in which time-dependent processes such as changes in redox potential can take place. Data obtained for radioactive iodine (a key radionuclide in the consideration of radioactive waste disposal) are presented and indicate that soil moisture content, particularly in conjunction with soil redox potential (through water-logging of the soil), has a marked effect on measured K d values. The results indicate the advantages and potential usefulness of the mini-column approach in assessing the environmental behaviour of radioactive, and other, soil contaminants

Transparency in European banking system – a technical and economic approach

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Ștefănescu Cristina Alexandrina

2014-03-01

Full Text Available The objective of our paper is to provide a comprehensive analysis of possible relationships between two different approaches of “transparency” – the technical vs. the economic one. Thus, irrespective of prior literature, our paper goes beyond a “solo” analysis of either of two above-mentioned “facets”, by providing a combined study. So, we focused on both (1 XBRL’s role in enhancing the quality of disclosure, by assessing its benefices and consequences and (2 corporate governance mechanism’s power to improve efficiency and effectiveness of banking supervision by encouraging transparency. The results of the performed analysis generally reveal that there is a strong and positive relationship between the level of disclosure promoted by corporate governance codes enforced in European Union countries and the degree of implementation of both XBRL-based projects designed for banking environment (FINREP and COREP. Consequently, we can assert that there is a consensus between the economic and technical approach of transparency in European banking system

From Physical Process to Economic Cost - Integrated Approaches of Landslide Risk Assessment

Science.gov (United States)

Klose, M.; Damm, B.

2014-12-01

The nature of landslides is complex in many respects, with landslide hazard and impact being dependent on a variety of factors. This obviously requires an integrated assessment for fundamental understanding of landslide risk. Integrated risk assessment, according to the approach presented in this contribution, implies combining prediction of future landslide occurrence with analysis of landslide impact in the past. A critical step for assessing landslide risk in integrated perspective is to analyze what types of landslide damage affected people and property in which way and how people contributed and responded to these damage types. In integrated risk assessment, the focus is on systematic identification and monetization of landslide damage, and analytical tools that allow deriving economic costs from physical landslide processes are at the heart of this approach. The broad spectrum of landslide types and process mechanisms as well as nonlinearity between landslide magnitude, damage intensity, and direct costs are some main factors explaining recent challenges in risk assessment. The two prevailing approaches for assessing the impact of landslides in economic terms are cost survey (ex-post) and risk analysis (ex-ante). Both approaches are able to complement each other, but yet a combination of them has not been realized so far. It is common practice today to derive landslide risk without considering landslide process-based cause-effect relationships, since integrated concepts or new modeling tools expanding conventional methods are still widely missing. The approach introduced in this contribution is based on a systematic framework that combines cost survey and GIS-based tools for hazard or cost modeling with methods to assess interactions between land use practices and landslides in historical perspective. Fundamental understanding of landslide risk also requires knowledge about the economic and fiscal relevance of landslide losses, wherefore analysis of their

Quantitative redox imaging biomarkers for studying tissue metabolic state and its heterogeneity

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He N. Xu

2014-03-01

Full Text Available NAD+/NADH redox state has been implicated in many diseases such as cancer and diabetes as well as in the regulation of embryonic development and aging. To fluorimetrically assess the mitochondrial redox state, Dr. Chance and co-workers measured the fluorescence of NADH and oxidized flavoproteins (Fp including flavin–adenine–dinucleotide (FAD and demonstrated their ratio (i.e. the redox ratio is a sensitive indicator of the mitochondrial redox states. The Chance redox scanner was built to simultaneously measure NADH and Fp in tissue at submillimeter scale in 3D using the freeze-trap protocol. This paper summarizes our recent research experience, development and new applications of the redox scanning technique in collaboration with Dr. Chance beginning in 2005. Dr. Chance initiated or actively involved in many of the projects during the last several years of his life. We advanced the redox scanning technique by measuring the nominal concentrations (in reference to the frozen solution standards of the endogenous fluorescent analytes, i.e., [NADH] and [Fp] to quantify the redox ratios in various biological tissues. The advancement has enabled us to identify an array of the redox indices as quantitative imaging biomarkers (including [NADH], [Fp], [Fp]/([NADH]+[Fp], [NADH]/[Fp], and their standard deviations for studying some important biological questions on cancer and normal tissue metabolism. We found that the redox indices were associated or changed with (1 tumorigenesis (cancer versus non-cancer of human breast tissue biopsies; (2 tumor metastatic potential; (3 tumor glucose uptake; (4 tumor p53 status; (5 PI3K pathway activation in pre-malignant tissue; (6 therapeutic effects on tumors; (7 embryonic stem cell differentiation; (8 the heart under fasting. Together, our work demonstrated that the tissue redox indices obtained from the redox scanning technique may provide useful information about tissue metabolism and physiology status in normal

Characterization of Redox properties of humic materials

International Nuclear Information System (INIS)

Choppin, G.R.

1995-01-01

An important aspect of humic materials is the presence of stable free radicals as shown by the width of 1 H-NMR lines of humic acid in solution as well as ESR spectra of solid samples. Presumably, these are due to quinohdrone functional groups in the humic structure. These free radicals are assumed to be a source of the redox effects of humics in metal cations. Phenolic groups have also been proposed as a source of reduction potential in these substances. The reduction potential of humic material is 0.5-0.7 V (vs. the normal hydrogen electrode). In addition to this inherent redox property, humics undergo photolysis by sunlight in surface waters which results in the production of hydrogen peroxide. The latter can also result in redox reactions with metal cations. Such direct and indirect redox capability can have significant effects on the migration of reducible cations. Studies of the reduction of hexavalent actinide cations by humic acid showed the reactions Np O 2 2+ -> Np O 2 + (E 1/2 0 = 1.47 V) and Pu O 2 2+ -> Pu +4 (E 1/2 0 = 1.04 V) while U O 2 2+ was not reduced. The reduction of plutonium in sea water by humics is discussed. Evidence of the effects of redox by humic material on metal cations in natural waters and sediments are also reviewed. (authors). 16 refs., 2 figs., 1 tab

Scleroglucan-borax hydrogel: a flexible tool for redox protein immobilization.

Science.gov (United States)

Frasconi, Marco; Rea, Sara; Matricardi, Pietro; Favero, Gabriele; Mazzei, Franco

2009-09-15

A highly stable biological film was prepared by casting an aqueous dispersion of protein and composite hydrogel obtained from the polysaccharide Scleroglucan (Sclg) and borax as a cross-linking agent. Heme proteins, such as hemoglobin (Hb), myoglobin (Mb), and horseradish peroxidase (HRP), were chosen as model proteins to investigate the immobilized system. A pair of well-defined quasi-reversible redox peaks, characteristics of the protein heme FeII/FeIII redox couples, were obtained at the Sclg-borax/proteins films on pyrolytic graphite (PG) electrodes, as a consequence of the direct electron transfer between the protein and the PG electrode. A full characterization of the electron transfer kinetic was performed by opportunely modeling data obtained from cyclic voltammetry and square wave voltammetry experiments. The efficiency of our cross-linking approach was investigated by studying the influence of different borax groups percentage in the Sclg matrix, revealing the versatility of this hydrogel in the immobilization of redox proteins. The native conformation of the three heme proteins entrapped in the hydrogel films were proved to be unchanged, reflected by the unaltered Soret adsorption band and by the catalytic activity toward hydrogen peroxide (H2O2). The main kinetic parameters, such as the apparent Michaelis-Menten constant, for the electrocatalytic reaction were also evaluated. The peculiar characteristics of Sclg-borax matrix make it possible to find wide opportunities as proteins immobilizing agent for studies of direct electrochemistry and biosensors development.

Methodical Approach to Diagnostics of Efficiency of Production Economic Activity of an Enterprise

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Zhukov Andrii V.

2014-03-01

Full Text Available The article offers developments of a methodical approach to diagnostics of efficiency of production economic activity of an enterprise, which, unlike the existing ones, is realised through the following stages: analysis of the enterprise external environment; analysis of the enterprise internal environment; identification of components of efficiency of production economic activity for carrying out complex diagnostics by the following directions: efficiency of subsystems of the enterprise production economic activity, efficiency of use of separate types of resources and socio-economic efficiency; scorecard formation; study of tendencies of change of indicators; identification of cause-effect dependencies between the main components of efficiency for diagnosing reasons of its level; diagnosing deviations of indicator values from their optimal values; development of a managerial decision on preserving and increasing efficiency of production economic activity of the enterprise.

Redox front formation in an uplifting sedimentary rock sequence: An analogue for redox-controlling processes in the geosphere around deep geological repositories for radioactive waste

International Nuclear Information System (INIS)

Yoshida, H.; Metcalfe, R.; Yamamoto, K.; Murakami, Y.; Hoshii, D.; Kanekiyo, A.; Naganuma, T.; Hayashi, T.

2008-01-01

Subsurface redox fronts control the mobilization and fixation of many trace elements, including potential pollutants such as certain radionuclides. Any safety assessment for a deep geological repository for radioactive wastes needs to take into account adequately the long-term redox processes in the geosphere surrounding the repository. To build confidence in understanding these processes, a redox front in a reduced siliceous sedimentary rock distributed in an uplifting area in Japan has been studied in detail. Geochemical analyses show increased concentrations of Fe and trace elements, including rare earth elements (REEs), at the redox front, even though concentrations of reduced rock matrix constituents show little change. Detailed SEM observations revealed that fossilized microorganisms composed of amorphous granules made exclusively of Fe and Si occur in the rock's pore space. Microbial 16S rDNA analysis suggests that there is presently a zonation of different bacterial groups within the redox band, and bacterial zonation played an important role in the concentration of Fe-oxyhydroxides at the redox front. These water-rock-microbe interactions can be considered analogous to the processes occurring in the redox fronts that would develop around geological repositories for radioactive waste. Once formed, the Fe-oxyhydroxides within such a front would be preserved even after reducing conditions resume following repository closure

Redox front formation in an uplifting sedimentary rock sequence: An analogue for redox-controlling processes in the geosphere around deep geological repositories for radioactive waste

Energy Technology Data Exchange (ETDEWEB)

Yoshida, H. [Nagoya University Museum, Material Research Section, Furocho, Nagoya 464-8602 (Japan)], E-mail: dora@num.nagoya-u.ac.jp; Metcalfe, R. [Quintessa Japan, Queen' s Tower A7-707, Minatomirai, Yokohama 220-6007 (Japan); Yamamoto, K. [Nagoya University Museum, Material Research Section, Furocho, Nagoya 464-8602 (Japan); Murakami, Y. [Japan Atomic Energy Agency (JAEA), Tono Geoscience Centre (Japan); Hoshii, D.; Kanekiyo, A.; Naganuma, T. [Hiroshima University, Higashi Hiroshima, Kagamiyama 1-4-4 (Japan); Hayashi, T. [Asahi University, Department of Dental Pharmacology, Hozumi, Gifu (Japan)

2008-08-15

Subsurface redox fronts control the mobilization and fixation of many trace elements, including potential pollutants such as certain radionuclides. Any safety assessment for a deep geological repository for radioactive wastes needs to take into account adequately the long-term redox processes in the geosphere surrounding the repository. To build confidence in understanding these processes, a redox front in a reduced siliceous sedimentary rock distributed in an uplifting area in Japan has been studied in detail. Geochemical analyses show increased concentrations of Fe and trace elements, including rare earth elements (REEs), at the redox front, even though concentrations of reduced rock matrix constituents show little change. Detailed SEM observations revealed that fossilized microorganisms composed of amorphous granules made exclusively of Fe and Si occur in the rock's pore space. Microbial 16S rDNA analysis suggests that there is presently a zonation of different bacterial groups within the redox band, and bacterial zonation played an important role in the concentration of Fe-oxyhydroxides at the redox front. These water-rock-microbe interactions can be considered analogous to the processes occurring in the redox fronts that would develop around geological repositories for radioactive waste. Once formed, the Fe-oxyhydroxides within such a front would be preserved even after reducing conditions resume following repository closure.

Redox-induced reversible luminescence switching of cerium-doped upconversion nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Huang, Yanan [College of Sciences, Shanghai University, Shanghai 200444 (China); International Laboratory for Adaptive Bio-nanotechnology, Suzhou Institute of Nano-tech and Nano-bionics (SINANO), Chinese Academy of Science, Suzhou 215123 (China); Xiao, Qingbo, E-mail: qbxiao2011@sinano.ac.cn [International Laboratory for Adaptive Bio-nanotechnology, Suzhou Institute of Nano-tech and Nano-bionics (SINANO), Chinese Academy of Science, Suzhou 215123 (China); Wang, Jian [College of Sciences, Shanghai University, Shanghai 200444 (China); International Laboratory for Adaptive Bio-nanotechnology, Suzhou Institute of Nano-tech and Nano-bionics (SINANO), Chinese Academy of Science, Suzhou 215123 (China); Xi, Yonglan [Laboratory for Agricultural Wastes Treatment and Recycling Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Science, Nanjing 210014 (China); Li, Fujin [International Laboratory for Adaptive Bio-nanotechnology, Suzhou Institute of Nano-tech and Nano-bionics (SINANO), Chinese Academy of Science, Suzhou 215123 (China); Feng, Yamin [College of Sciences, Shanghai University, Shanghai 200444 (China); International Laboratory for Adaptive Bio-nanotechnology, Suzhou Institute of Nano-tech and Nano-bionics (SINANO), Chinese Academy of Science, Suzhou 215123 (China); Shi, Liyi [College of Sciences, Shanghai University, Shanghai 200444 (China); Lin, Hongzhen, E-mail: hzlin2010@sinano.ac.cn [International Laboratory for Adaptive Bio-nanotechnology, Suzhou Institute of Nano-tech and Nano-bionics (SINANO), Chinese Academy of Science, Suzhou 215123 (China)

2016-05-15

Smart upconversion nanophosphors (UCNPs) that can be reversibly switched between two or more luminescent states by certain external stimuli have attracted considerable attention due to their great potential in biological applications. Here we report for the first time a type of redox-switchable UCNPs by codoping NaGdF{sub 4}:Yb/Er nanorods with the redox-active Ce{sup 3+}/Ce{sup 4+} ion pairs. A reversible switching of their UC luminescence intensity was observed upon the variation of the surrounding redox environments. We show solid proof that the luminescence switching is caused by the tailoring of the NaGdF{sub 4} host crystal structure in response to changing redox state of the codoped cerium ions. A proof-of-concept example is further demonstrated by using these UCNPs for probing the dynamical variation of redox environments in biological tissues. - Highlights: • Synthesis of upconversion nanoparticles doped with Ce{sup 3+}/Ce{sup 4+} ions. • The precise and reversible modification of crystal structure by redox reactions. • Tuning the upconversion luminescence by tailoring the crystal structure.

A study of redox kinetic in silicate melt

International Nuclear Information System (INIS)

Magnien, V.

2005-12-01

The aim of this thesis is to understand better iron redox reactions and mechanisms in silicate glasses and melts. Particular interest has been paid to the influence of temperature and chemical composition. For this purpose, the influence of alkali element content, iron content and network formers on the kinetics of redox reactions has been determined through XANES and Raman spectroscopy experiments performed either near the glass transition or above the liquidus temperature. As a complement, electrical conductivity and RBS spectroscopy experiments have been made to characterize the diffusivity of the species that transport electrical charges and the reaction morphology, respectively. Temperature and composition variations can induce changes in the dominating redox mechanism. At a given temperature, the parameters that exert the strongest influence on redox mechanisms are the presence or lack of divalent cations and the existing decoupling between the mobility of network former and modifier elements. Near Tg, the diffusion of divalent cations, when present in the melt, controls the kinetics of iron redox reactions along with a flux of electron holes. Composition, through the degree of polymerization and the silicate network structure, influences the kinetics and the nature of the involved cations, but not the mechanisms of the reaction. Without alkaline earth elements, the kinetics of redox reactions are controlled by the diffusion of oxygen species. With increasing temperatures, the diffusivities of all ionic species tend to become similar. The decoupling between ionic fluxes then is reduced so that several mechanisms become kinetically equivalent and can thus coexist. (author)

John Dewey’s theory of democracy and its links with the heterodox approach to economics.

Directory of Open Access Journals (Sweden)

Arturo Hermann

2011-07-01

Full Text Available John Dewey is one of the most significant figures in pragmatist philosophy, an approach which he systematically applied to the study of economic, social and cultural structure. In our work, we will focus on the main aspects of Dewey’s approach to the study of aspects that make up “human nature” and how do they interact with the characteristics of the cultural context. We will illustrate how the concepts elaborated by Dewey can contribute to the heterodox analysis of a host of economic and social issues. Dewey highlights the crucial role of public policies for facilitating the development of volunteer associations in all areas of the social structure. In the analysis of these aspects, Dewey’s key contribution lies in removing the concepts of democracy and participation from the limbo of abstraction in which they tended to be confined by previous approaches and connecting them to the evolution of economic and social forms.

Le reazioni redox: un pasticcio concettuale?

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Elena Ghibaudi

2015-10-01

Full Text Available Le reazioni di ossidoriduzione costituiscono un argomento centrale di qualsiasi corso di base di chimica, sia a livello scolastico che universitario. Il loro apprendimento comporta il superamento di svariati ostacoli concettuali, la cui difficoltà può risultare amplificata da prassi didattiche inadeguate. Gli errori più ricorrenti nel presentare l’argomento sono di due tipi: i fare implicitamente riferimento a modelli esplicativi distinti (es. il numero di ossidazione e il trasferimento elettronico, senza esplicitarli e senza evidenziarne la differente natura e il campo di validità; ii confondere il livello della spiegazione formale con quello della realtà fisica. I fenomeni redox sono normalmente interpretati sulla base di tre distinti modelli empirici, che fanno riferimento al trasferimento di atomi di ossigeno, di atomi di idrogeno, di elettroni; e di un quarto modello, formale, fondato sul cambiamento del numero di ossidazione. La confusione tra questi modelli può generare considerevoli problemi di apprendimento. Il presente lavoro riporta un’analisi critica delle implicazioni concettuali della didattica dei processi redox. L’analisi è articolata in tre sezioni: i disamina della evoluzione storica del concetto di ossidoriduzione; ii analisi dei modelli redox e del loro campo di validità; iii discussione di alcuni aspetti epistemologici inerenti i processi redox che sono rilevanti per la didattica della chimica.

Examining carbon emissions economic growth nexus for India: A multivariate cointegration approach

International Nuclear Information System (INIS)

Ghosh, Sajal

2010-01-01

The study probes cointegration and causality between carbon emissions and economic growth for India using ARDL bounds testing approach complemented by Johansen-Juselius maximum likelihood procedure in a multivariate framework by incorporating energy supply, investment and employment for time span 1971-2006. The study fails to establish long-run equilibrium relationship and long term causality between carbon emissions and economic growth; however, there exists a bi-directional short-run causality between the two. Hence, in the short-run, any effort to reduce carbon emissions could lead to a fall in the national income. This study also establishes unidirectional short-run causality running from economic growth to energy supply and energy supply to carbon emissions. The absence of causality running from energy supply to economic growth implies that in India, energy conservation and energy efficiency measures can be implemented to minimize the wastage of energy across value chain. Such measures would narrow energy demand-supply gap. Absence of long-run causality between carbon emissions and economic growth implies that in the long-run, focus should be given on harnessing energy from clean sources to curb carbon emissions, which would not affect the country's economic growth.

The mechanism of mediated oxidation of carboxylates with ferrocene as redox catalyst in absence of grafting effects. An experimental and theoretical approach

International Nuclear Information System (INIS)

Hernández-Muñoz, Lindsay S.; Galano, Annia; Astudillo-Sánchez, Pablo D.; Abu-Omar, Mahdi M.; González, Felipe J.

2014-01-01

Graphical abstract: - Highlights: • The mechanism of mediated oxidation of carboxylates. • Thermodynamics of the mediated Kolbe and Non-Kolbe mechanisms. • The oxidation of acetate and diphenylacetate ions by using ferrocene as redox catalyst. • Simulation and DFT calculations of the mediated oxidation of carboxylates. • Radical and carbocationic pathways in the carboxylate oxidation in acetonitrile. - Abstract: The oxidation of tetrabutylammonium carboxylates by using ferrocene derivatives as redox mediators has been recently used to perform the covalent grafting of carbon surfaces with organic and organometallic groups. Due to the intervention of this surface process, a partial description of the reaction mechanism has only been stated. Therefore, this article concerns about two features of the oxidation of carboxylates mediated by ferrocene. In the first part, it is discussed that in the oxidation of acetate ions by using ferrocene as redox catalyst, the gap between both oxidation potentials is very high, which means that the homogeneous electron transfer between the acetate ion and the electrochemically generated ferrocenium ion is energetically unfavorable. However, by using density functional theory calculations, it has been shown that the whole set of coupled chemical reactions involved either in a Kolbe or Non-Kolbe pathway drive the overall mechanisms towards a thermodynamically favorable situation. In order to avoid the strong covalent grafting process that occurs during the mediated oxidation of acetate ions, the second part of this work deals with the oxidation of tetrabutylammonium diphenylacetate by using ferrocene as a redox mediator in acetonitrile on glassy carbon electrodes. With this carboxylate, no electrode inhibition process occurs and, therefore cyclic voltammetry simulation was done to propose the electrochemical and chemical steps that are present when a carboxylate oxidation is performed in the presence of ferrocene derivatives

Tourism and Economic Growth in Sri Lanka: An ARDL Bounds Testing Approach

OpenAIRE

P. Srinivasan; Santhosh Kumar P. K; L. Ganesh

2012-01-01

The purpose of the study is to examine the impact of tourism on economic growth in Sri Lanka through the Autoregressive Distributed Lag (ARDL) bounds testing approach. The analysis was carried out for the period from 1969 to 2009. By and large, our analysis reveals that the tourism has a positive impact on economic growth in Sri Lanka both in the short-run and long-run. Hence, it is crucial for the Sri Lankan government to achieve unification and stability by focusing on political solutions t...

Molecular Orbital Principles of Oxygen-Redox Battery Electrodes.

Science.gov (United States)

Okubo, Masashi; Yamada, Atsuo

2017-10-25

Lithium-ion batteries are key energy-storage devices for a sustainable society. The most widely used positive electrode materials are LiMO 2 (M: transition metal), in which a redox reaction of M occurs in association with Li + (de)intercalation. Recent developments of Li-excess transition-metal oxides, which deliver a large capacity of more than 200 mAh/g using an extra redox reaction of oxygen, introduce new possibilities for designing higher energy density lithium-ion batteries. For better engineering using this fascinating new chemistry, it is necessary to achieve a full understanding of the reaction mechanism by gaining knowledge on the chemical state of oxygen. In this review, a summary of the recent advances in oxygen-redox battery electrodes is provided, followed by a systematic demonstration of the overall electronic structures based on molecular orbitals with a focus on the local coordination environment around oxygen. We show that a π-type molecular orbital plays an important role in stabilizing the oxidized oxygen that emerges upon the charging process. Molecular orbital principles are convenient for an atomic-level understanding of how reversible oxygen-redox reactions occur in bulk, providing a solid foundation toward improved oxygen-redox positive electrode materials for high energy-density batteries.

Synthesis and characterization of redox-active ferric nontronite

Energy Technology Data Exchange (ETDEWEB)

Ilgen, A. G.; Kukkadapu, R. K.; Dunphy, D. R.; Artyushkova, K.; Cerrato, J. M.; Kruichak, J. N.; Janish, M. T.; Sun, C. J.; Argo, J. M.; Washington, R. E.

2017-10-01

Heterogeneous redox reactions on clay mineral surfaces control mobility and bioavailability of redox-sensitive nutrients and contaminants. Iron (Fe) residing in clay mineral structures can either catalyze or directly participate in redox reactions; however, chemical controls over its reactivity are not fully understood. In our previous work we demonstrated that converting a minor portion of Fe(III) to Fe(II) (partial reduction) in the octahedral sheet of natural Fe-rich clay mineral nontronite (NAu-1) activates its surface, making it redox-active. In this study we produced and characterized synthetic ferric nontronite (SIP), highlighting structural and chemical similarities and differences between this synthetic nontronite and its natural counterpart NAu-1, and probed whether mineral surface is redox-active by reacting it with arsenic As(III) under oxic and anoxic conditions. We demonstrate that synthetic nontronite SIP undergoes the same activation as natural nontronite NAu-1 following the partial reduction treatment. Similar to NAu-1, SIP oxidized As(III) to As(V) under both oxic (catalytic pathway) and anoxic (direct oxidation) conditions. The similar reactivity trends observed for synthetic nontronite and its natural counterpart make SIP an appropriate analog for laboratory studies. The development of chemically pure analogs for ubiquitous soil minerals will allow for systematic research of the fundamental properties of these minerals.

Anticancer Activity of Metal Complexes: Involvement of Redox Processes

Science.gov (United States)

Jungwirth, Ute; Kowol, Christian R.; Keppler, Bernhard K.; Hartinger, Christian G.; Berger, Walter; Heffeter, Petra

2012-01-01

Cells require tight regulation of the intracellular redox balance and consequently of reactive oxygen species for proper redox signaling and maintenance of metal (e.g., of iron and copper) homeostasis. In several diseases, including cancer, this balance is disturbed. Therefore, anticancer drugs targeting the redox systems, for example, glutathione and thioredoxin, have entered focus of interest. Anticancer metal complexes (platinum, gold, arsenic, ruthenium, rhodium, copper, vanadium, cobalt, manganese, gadolinium, and molybdenum) have been shown to strongly interact with or even disturb cellular redox homeostasis. In this context, especially the hypothesis of “activation by reduction” as well as the “hard and soft acids and bases” theory with respect to coordination of metal ions to cellular ligands represent important concepts to understand the molecular modes of action of anticancer metal drugs. The aim of this review is to highlight specific interactions of metal-based anticancer drugs with the cellular redox homeostasis and to explain this behavior by considering chemical properties of the respective anticancer metal complexes currently either in (pre)clinical development or in daily clinical routine in oncology. PMID:21275772

The Development of the Redox Concept Inventory as a Measure of Students' Symbolic and Particulate Redox Understandings and Confidence

Science.gov (United States)

Brandriet, Alexandra R.; Bretz, Stacey Lowery

2014-01-01

This article describes the development of the Redox Concept Inventory (ROXCI) as a measure of students' understandings and confidence of both the symbolic and particulate domains of oxidation-reduction (redox) reactions. The ROXCI was created using a mixed-methods design in which the items were developed based upon themes that emerged from…

Redox homeostasis: the linchpin in stem cell self-renewal and differentiation.

Science.gov (United States)

Wang, Kui; Zhang, Tao; Dong, Qiang; Nice, Edouard Collins; Huang, Canhua; Wei, Yuquan

2013-03-14

Stem cells are characterized by their unique ability of self-renewal to maintain the so-called stem cell pool. Over the past decades, reactive oxygen species (ROS) have been recognized as toxic aerobic metabolism byproducts that are harmful to stem cells, leading to DNA damage, senescence or cell death. Recently, a growing body of literature has shown that stem cells reside in redox niches with low ROS levels. The balance of Redox homeostasis facilitates stem cell self-renewal by an intricate network. Thus, to fully decipher the underlying molecular mechanisms involved in the maintenance of stem cell self-renewal, it is critical to address the important role of redox homeostasis in the regulation of self-renewal and differentiation of stem cells. In this regard, we will discuss the regulatory mechanisms involved in the subtly orchestrated balance of redox status in stem cells by scavenger antioxidant enzyme systems that are well monitored by the hypoxia niches and crucial redox regulators including forkhead homeobox type O family (FoxOs), apurinic/apyrimidinic (AP) endonuclease1/redox factor-1 (APE1/Ref-1), nuclear factor erythroid-2-related factor 2 (Nrf2) and ataxia telangiectasia mutated (ATM). We will also introduce several pivotal ROS-sensitive molecules, such as hypoxia-inducible factors, p38 mitogen-activated protein kinase (p38) and p53, involved in the redox-regulated stem cell self-renewal. Specifically, all the aforementioned molecules can act as 'redox sensors' by virtue of redox modifications of their cysteine residues, which are critically important in the control of protein function. Given the importance of redox homeostasis in the regulation of stem cell self-renewal, understanding the underlying molecular mechanisms involved will provide important new insights into stem cell biology.

Adaptation, interaction and urgency : a complex evolutionary economic geography approach to leisure

NARCIS (Netherlands)

Meekes, Jasper F.; Buda, Dorina M.; de Roo, Gert

2017-01-01

Local and regional governments in western European peripheral areas aim to spur leisure-led regional development. We explore planning for leisure by applying an evolutionary economic geography (EEG) approach from a complexity perspective. We identify conditions which enable and constrain leisure

Electrochemical redox processes involving soluble cerium species

International Nuclear Information System (INIS)

Arenas, L.F.; Ponce de León, C.; Walsh, F.C.

2016-01-01

Highlights: • The relevance of cerium in laboratory and industrial electrochemistry is considered. • The history of fundamental electrochemical studies and applications is considered. • The chemistry, redox thermodynamics and electrode kinetics of cerium are summarised. • The uses of cerium ions in synthesis, energy storage, analysis and environmental treatment are illustrated. • Research needs and development perspectives are discussed. - Abstract: Anodic oxidation of cerous ions and cathodic reduction of ceric ions, in aqueous acidic solutions, play an important role in electrochemical processes at laboratory and industrial scale. Ceric ions, which have been used for oxidation of organic wastes and off-gases in environmental treatment, are a well-established oxidant for indirect organic synthesis and specialised cleaning processes, including oxide film removal from tanks and process pipework in nuclear decontamination. They also provide a classical reagent for chemical analysis in the laboratory. The reversible oxidation of cerous ions is an important reaction in the positive compartment of various redox flow batteries during charge and discharge cycling. A knowledge of the thermodynamics and kinetics of the redox reaction is critical to an understanding of the role of cerium redox species in these applications. Suitable choices of electrode material (metal or ceramic; coated or uncoated), geometry/structure (2-or 3-dimensional) and electrolyte flow conditions (hence an acceptable mass transport rate) are critical to achieving effective electrocatalysis, a high performance and a long lifetime. This review considers the electrochemistry of soluble cerium species and their diverse uses in electrochemical technology, especially for redox flow batteries and mediated electrochemical oxidation.

Thiol Redox Transitions in Cell Signaling: a Lesson from N-Acetylcysteine

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Tiziana Parasassi

2010-01-01

Full Text Available The functional status of cells is under the control of external stimuli affecting the function of critical proteins and eventually gene expression. Signal sensing and transduction by messengers to specific effectors operate by post-translational modification of proteins, among which thiol redox switches play a fundamental role that is just beginning to be understood. The maintenance of the redox status is, indeed, crucial for cellular homeostasis and its dysregulation towards a more oxidized intracellular environment is associated with aberrant proliferation, ultimately related to diseases such as cancer, cardiovascular disease, and diabetes. Redox transitions occur in sensitive cysteine residues of regulatory proteins relevant to signaling, their evolution to metastable disulfides accounting for the functional redox switch. N-acetylcysteine (NAC is a thiol-containing compound that is able to interfere with redox transitions of thiols and, thus, in principle, able to modulate redox signaling. We here review the redox chemistry of NAC, then screen possible mechanisms to explain the effects observed in NAC-treated normal and cancer cells; such effects involve a modification of global gene expression, thus of functions and morphology, with a leitmotif of a switch from proliferation to terminal differentiation. The regulation of thiol redox transitions in cell signaling is, therefore, proposed as a new tool, holding promise not only for a deeper explanation of mechanisms, but indeed for innovative pharmacological interventions.

Exercise and Glycemic Control: Focus on Redox Homeostasis and Redox-Sensitive Protein Signaling

Science.gov (United States)

Parker, Lewan; Shaw, Christopher S.; Stepto, Nigel K.; Levinger, Itamar

2017-01-01

Physical inactivity, excess energy consumption, and obesity are associated with elevated systemic oxidative stress and the sustained activation of redox-sensitive stress-activated protein kinase (SAPK) and mitogen-activated protein kinase signaling pathways. Sustained SAPK activation leads to aberrant insulin signaling, impaired glycemic control, and the development and progression of cardiometabolic disease. Paradoxically, acute exercise transiently increases oxidative stress and SAPK signaling, yet postexercise glycemic control and skeletal muscle function are enhanced. Furthermore, regular exercise leads to the upregulation of antioxidant defense, which likely assists in the mitigation of chronic oxidative stress-associated disease. In this review, we explore the complex spatiotemporal interplay between exercise, oxidative stress, and glycemic control, and highlight exercise-induced reactive oxygen species and redox-sensitive protein signaling as important regulators of glucose homeostasis. PMID:28529499

Investigation of a redox-sensitive predictive model of mouse embryonic stem cells differentiation using quantitative nuclease protection assays and glutathione redox status

Science.gov (United States)

Investigation of a redox-sensitive predictive model of mouse embryonic stem cell differentiation via quantitative nuclease protection assays and glutathione redox status Chandler KJ,Hansen JM, Knudsen T,and Hunter ES 1. U.S. Environmental Protection Agency, Research Triangl...

The Methodical Approaches to the Research of Informatization of the Global Economic Development

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Kazakova Nadezhda A.

2018-03-01

Full Text Available The article is aimed at researching the identification of global economic development informatization. The complex of issues connected with research of development of informatization of the world countries in the conditions of globalization is considered. The development of informatization in the global economic space, which facilitates opening of new markets for international trade enterprises, international transnational corporations and other organizations, which not only provide exports, but also create production capacities for local producers. The methodical approach which includes three stages together with formation of the input information on the status of informatization of the global economic development of the world countries has been proposed.

Redox non-innocent ligands: versatile new tools to control catalytic reactions

NARCIS (Netherlands)

Lyaskovskyy, V.; de Bruin, B.

2012-01-01

In this (tutorial overview) perspective we highlight the use of "redox non-innocent" ligands in catalysis. Two main types of reactivity in which the redox non-innocent ligand is involved can be specified: (A) The redox active ligand participates in the catalytic cycle only by accepting/donating

Redox behavior of Ce(IV)/Ce(III) in the presence of nitrilotriacetic acid: a surrogate study for An(IV)/An(III) redox behavior

International Nuclear Information System (INIS)

Suzuki, Y.; Nankawa, T.; Ohnuki, T.; Francis, A.J.

2010-01-01

Using cyclic voltammetry, we investigated the redox behavior of Ce(IV)/Ce(III), which is a surrogate for An(IV)/An(III) (An = actinides), in a solution of nitrilotriacetic acid (NTA) at 25 C. The cyclic voltammogram of Ce in a 0.1 M NTA solution at pH 6 showed a reversible one-electron redox reaction for Ce(IV)/Ce(III) at 0.51 V vs. Ag/AgCl. This redox potential was much lower than that obtained in 1 M nitric acid, indicating that Ce(IV) was preferentially stabilized by complexation with NTA. The redox potential in the NTA solution was independent of the Ce concentration from 2 to 20 mM, NTA concentration from 5 to 200 mM and pH between 3 and 7. These results indicated that no polymerization and no additional coordination of NTA and OH to the Ce(III)-NTA complex took place during the redox reaction. As the speciation calculation of Ce(III) in the NTA solution showed that the predominant species was Ce III (nta) 2 3 (H 3 nta = NTA), the redox reaction of the Ce-NTA complex was expressed by the following: Ce IV (nta) 2 2- + e - ↔ Ce III (nta) 2 3 . The logarithm of the stability constant of Ce IV (nta) 2 2- was calculated to be 38.6 ± 0.8 for I = 0 from the redox potential shift of Ce(IV)/Ce(III) in the NTA solution. The value was in good accordance with the stability constant of the Np IV (nta) 2 2- complex, demonstrating that the aqueous coordination chemistry of Ce(IV) with NTA is quite similar to that of An(IV). These results strongly suggest that a negative shift of the Pu(IV)/Pu(III) redox potential in the NTA solution should make Pu(IV) more stable than Pu(III) even in a reducing environment. (orig.)

New Approach in Translational Medicine: Effects of Electrolyzed Reduced Water (ERW on NF-κB/iNOS Pathway in U937 Cell Line under Altered Redox State

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Sara Franceschelli

2016-09-01

Full Text Available It is known that increased levels of reactive oxygen species (ROS and reactive nitrogen species (RNS can exert harmful effects, altering the cellular redox state. Electrolyzed Reduced Water (ERW produced near the cathode during water electrolysis exhibits high pH, high concentration of dissolved hydrogen and an extremely negative redox potential. Several findings indicate that ERW had the ability of a scavenger free radical, which results from hydrogen molecules with a high reducing ability and may participate in the redox regulation of cellular function. We investigated the effect of ERW on H2O2-induced U937 damage by evaluating the modulation of redox cellular state. Western blotting and spectrophotometrical analysis showed that ERW inhibited oxidative stress by restoring the antioxidant capacity of superoxide dismutase, catalase and glutathione peroxidase. Consequently, ERW restores the ability of the glutathione reductase to supply the cell of an important endogenous antioxidant, such as GSH, reversing the inhibitory effect of H2O2 on redox balance of U937 cells. Therefore, this means a reduction of cytotoxicity induced by peroxynitrite via a downregulation of the NF-κB/iNOS pathway and could be used as an antioxidant for preventive and therapeutic application. In conclusion, ERW can protect the cellular redox balance, reducing the risk of several diseases with altered cellular homeostasis such as inflammation.

Redox Control of Skeletal Muscle Regeneration.

Science.gov (United States)

Le Moal, Emmeran; Pialoux, Vincent; Juban, Gaëtan; Groussard, Carole; Zouhal, Hassane; Chazaud, Bénédicte; Mounier, Rémi

2017-08-10

Skeletal muscle shows high plasticity in response to external demand. Moreover, adult skeletal muscle is capable of complete regeneration after injury, due to the properties of muscle stem cells (MuSCs), the satellite cells, which follow a tightly regulated myogenic program to generate both new myofibers and new MuSCs for further needs. Although reactive oxygen species (ROS) and reactive nitrogen species (RNS) have long been associated with skeletal muscle physiology, their implication in the cell and molecular processes at work during muscle regeneration is more recent. This review focuses on redox regulation during skeletal muscle regeneration. An overview of the basics of ROS/RNS and antioxidant chemistry and biology occurring in skeletal muscle is first provided. Then, the comprehensive knowledge on redox regulation of MuSCs and their surrounding cell partners (macrophages, endothelial cells) during skeletal muscle regeneration is presented in normal muscle and in specific physiological (exercise-induced muscle damage, aging) and pathological (muscular dystrophies) contexts. Recent advances in the comprehension of these processes has led to the development of therapeutic assays using antioxidant supplementation, which result in inconsistent efficiency, underlying the need for new tools that are aimed at precisely deciphering and targeting ROS networks. This review should provide an overall insight of the redox regulation of skeletal muscle regeneration while highlighting the limits of the use of nonspecific antioxidants to improve muscle function. Antioxid. Redox Signal. 27, 276-310.

The Analysis of Theoretical Approaches to Identification of Factors of Regional Economic Growth

Directory of Open Access Journals (Sweden)

Kosyrieva Olena V.

2016-05-01

Full Text Available The article is devoted to the investigation of current approaches to identification of factors of economic growth in the regions. The theory of new economic geography based on works and studies of P. Krugman has been considered. There highlighted the key issues of regional economic growth requiring an in-depth studying and consideration in the elaboration of strategies for sustainable development of the regions. The views of leading domestic and foreign scholars as well as the OECD experts, the World Bank, the National Statistics Service of the United Kingdom and others on the main drivers of economic growth have been analyzed. On the basis of the study the factors of regional economic growth most commonly encountered in theory and practice have been generalized. It is proved that scientists and analysts most often classify as the factors of regional economic growth the following ones: those characterizing human potential, scientific-technical and innovative activity, management and institutional capacity. The factors less frequently correlated by specialists and scientists with the regional economic growth include: those characterizing the environment, business and sociopolitical factors, which is associated with difficulty of their quantification, but in any case does not diminish their importance.

A novel ultrasonic velocity sensing approach to monitoring state of charge of vanadium redox flow battery

International Nuclear Information System (INIS)

Chou, Yi-Sin; Hsu, Ning-Yih; Jeng, King-Tsai; Chen, Kuan-Hsiang; Yen, Shi-Chern

2016-01-01

Highlights: • This is the first to apply ultrasonic sensing technique to monitor SOC of VRB. • Ultrasound velocity is affected by concentration and temperature of a solution. • The ultrasonic sensing is applicable to both positive and negative sides of VRB. • An empirical model equation fits the results of this two-component system well. • The SOC of a VRB can be properly measured using ultrasonic sensing. - Abstract: A novel ultrasonic velocity sensing approach is proposed and investigated to monitor the state of charge (SOC) of a vanadium redox flow battery (VRB, or VRFB). The positive electrode is designated as the energy storage capacity-limiting one so that the molar ratio of the V"5"+ ion in the positive electrolyte solution determines the SOC of a VRB. The tested single-cell VRB is connected to an ultrasonic sensor and charged/discharged almost to its two extremes at a constant current of 2 A under various operating temperatures. It is found that the ultrasound velocity exhibits distinct variations in accordance with changes of vanadium ion compositions in the positive electrolyte solution as the SOC of the VRB varies. The SOC obtained can be depicted in a 3D plot in terms of ultrasound velocity and operating temperature. An empirical model equation is proposed and found to fit the experimental results of both charging and discharging stages quite well. The advantages of this SOC sensing approach are that it is totally independent of VRB operations and can be readily applied to both sides of the electrodes. It is expected to develop into a dependable method for accurate and real-time monitoring of SOC for VRB.

Fenton Redox Chemistry : Arsenite Oxidation by Metallic Surfaces

NARCIS (Netherlands)

Borges Freitas, S.C.; Van Halem, D.; Badruzzaman, A.B.M.; Van der Meer, W.G.J.

2014-01-01

Pre-oxidation of As(III) is necessary in arsenic removal processes in order to increase its efficiency. Therefore, the Fenton Redox Chemistry is defined by catalytic activation of H2O2 and currently common used for its redox oxidative properties. In this study the effect of H2O2 production catalysed

Hourly and daily variation of sediment redox potential in tidal wetland sediments

Science.gov (United States)

Catallo, W. James

1999-01-01

Variation of electrochemical oxidation-reduction (redox) potential was examined in surface salt march sediments under conditions of flooding and tidal simulation in mesocosms and field sites. Time series were generated of redox potential measured in sediment profiles at 2-10 cm depth using combination Pt-Ag/AgCl (ORP) electrodes. Redox potential data were acquired at rapid rates (1-55 samples/h) over extended periods (3-104 days) along with similar times series of temperature (water, air, soil) and pH. It was found that redox potential vaired as a result of water level changes and was unrelated to diurnal changes in temperature or pH, the latter of which changed by 370 mV redox potential decrease in under 48 hours). Attenuatoin of microbial activity by [gamma] y-radiation and toxic chemicals elimintated this response. In tidal salt marsh mesocosms where the sediment-plant assemblages were exposed to a simulated diurnal tide, redox potenial oscillations of 40-300 mV amplitude were recoded that has the same periodicity as the flood-drain cycle. Periodic redoc potential time series were observed repeatedly in sediments receiving tidal pulsing but not in those sediments exposed to static hydrological conditions. Data collected over 12 days from a coastal marsh site experiencing diurnal tides showed similar fluctuations in redox potential. Data from the experimentents indicated that (a) redox potential can be a dynamic, nonlinear variable in coastal and estuarine wetland sediments over hourly and daily scales, and the designs of biogeochemical experiments should reflect this, (b) redox potential can change rapidly and signigicantly in coastal wetland sediments in response of flooding and draining, (c) microbial community processes are primarily determinants of the time course of redox potential in wetland sediments, and elimination of inhibition of microbial activity (e.g. by pollutants) can significantly alter that behavior, and (d) fast redox potential dynamics appear

The Effects of Unemployment on Economic Growth in Greece. An ARDL Bound Test Approach.

Directory of Open Access Journals (Sweden)

Nikolaos Dritsakis

2016-12-01

Full Text Available The aim of this paper is to investigate the relationship between unemployment rate, economic growth and inflation rate in Greece, using annual data covering the period 1995-2015. The unit root tests results indicated that the variables have different integration order. Subsequently, the bounds testing (ARDL approach and ECM-ARDL model are applied in order to examine the long-run and the causal relationship between the variables. The empirical results of the study revealed, both in the short and long-run, that there is a unidirectional causal relationship between unemployment and economic growth with direction from unemployment to economic growth, as well as a unidirectional causality running from inflation to economic growth.

Efficient Solar Energy Harvesting and Storage through a Robust Photocatalyst Driving Reversible Redox Reactions.

Science.gov (United States)

Zhou, Yangen; Zhang, Shun; Ding, Yu; Zhang, Leyuan; Zhang, Changkun; Zhang, Xiaohong; Zhao, Yu; Yu, Guihua

2018-06-14

Simultaneous solar energy conversion and storage is receiving increasing interest for better utilization of the abundant yet intermittently available sunlight. Photoelectrodes driving nonspontaneous reversible redox reactions in solar-powered redox cells (SPRCs), which can deliver energy via the corresponding reverse reactions, present a cost-effective and promising approach for direct solar energy harvesting and storage. However, the lack of photoelectrodes having both high conversion efficiency and high durability becomes a bottleneck that hampers practical applications of SPRCs. Here, it is shown that a WO 3 -decorated BiVO 4 photoanode, without the need of extra electrocatalysts, can enable a single-photocatalyst-driven SPRC with a solar-to-output energy conversion efficiency as high as 1.25%. This SPRC presents stable performance over 20 solar energy storage/delivery cycles. The high efficiency and stability are attributed to the rapid redox reactions, the well-matched energy level, and the efficient light harvesting and charge separation of the prepared BiVO 4 . This demonstrated device system represents a potential alternative toward the development of low-cost, durable, and easy-to-implement solar energy technologies. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optical imaging the redox status change during cell apoptosis

Science.gov (United States)

Su, Ting; Zhang, Zhihong; Lin, Juqiang; Luo, Qingming

2007-02-01

Many cellular events involve the alteration in redox equilibrium, globally or locally. In many cases, excessive reactive oxygen species (ROS) production is the underlying cause. Several green fluoresecence protein based indicators are constructed to measure redox status in cells, e.g, rxYFP and roGFPs, which allow real time detection. reduction and oxidization-sensitive GFP (RoGFPs) are more useful due to ratiometric variation by excitation, making the measurement more accurate. Utilizing one of those roGFPs called roGFP1, we establish a mitochondrial redox state probing platform in HeLa cells with laser scan confocal microscopy (LSCM) as detection system. Control experiments confirmed that our platform could produce stable ratiometric values, which made the data more accurately reflect the real environmental changes of redox status that roGFP1 probed. Using exogenous H IIO II and DTT, we evaluated the reactivity and reversibility of roGFP1. The minimal hydrogen peroxide concentration that roGFP1 could show detectable ratiometric changes in our system was about 200μM. Preliminarily applying our platform to exploring the redox status during apoptosis, we observed an increase in ratiometric, suggesting an excessive ROS production.

Subsurface Conditions Controlling Uranium Incorporation in Iron Oxides: A Redox Stable Sink

International Nuclear Information System (INIS)

Fendorf, Scott

2016-01-01

mechanism may help to explain U retention in some geologic materials, improving our understanding of U-based geochronology and the redox status of ancient geochemical environments. Additionally, U(VI) may be incorporated within silicate minerals though encapsulation of U-bearing iron oxides, leading to a redox stable solid. Our research detailing previously unrecognized mechanism of U incorporation within sediment minerals may even lead to new approaches for in situ contamination remediation techniques, and will help refine models of U fate and transport in reduced subsurface zones.

Subsurface Conditions Controlling Uranium Incorporation in Iron Oxides: A Redox Stable Sink

Energy Technology Data Exchange (ETDEWEB)

Fendorf, Scott [Stanford Univ., CA (United States)

2016-04-05

mechanism may help to explain U retention in some geologic materials, improving our understanding of U-based geochronology and the redox status of ancient geochemical environments. Additionally, U(VI) may be incorporated within silicate minerals though encapsulation of U-bearing iron oxides, leading to a redox stable solid. Our research detailing previously unrecognized mechanism of U incorporation within sediment minerals may even lead to new approaches for in situ contamination remediation techniques, and will help refine models of U fate and transport in reduced subsurface zones.

TEMPOL increases NAD+ and improves redox imbalance in obese mice

Directory of Open Access Journals (Sweden)

Mayumi Yamato

2016-08-01

Full Text Available Continuous energy conversion is controlled by reduction–oxidation (redox processes. NAD+ and NADH represent an important redox couple in energy metabolism. 4-Hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPOL is a redox-cycling nitroxide that promotes the scavenging of several reactive oxygen species (ROS and is reduced to hydroxylamine by NADH. TEMPOL is also involved in NAD+ production in the ascorbic acid–glutathione redox cycle. We utilized the chemical properties of TEMPOL to investigate the effects of antioxidants and NAD+/NADH modulators on the metabolic imbalance in obese mice. Increases in the NAD+/NADH ratio by TEMPOL ameliorated the metabolic imbalance when combined with a dietary intervention, changing from a high-fat diet to a normal diet. Plasma levels of the superoxide marker dihydroethidium were higher in mice receiving the dietary intervention compared with a control diet, but were normalized with TEMPOL consumption. These findings provide novel insights into redox regulation in obesity.

A robust and versatile mass spectrometry platform for comprehensive assessment of the thiol redox metabolome

Directory of Open Access Journals (Sweden)

T.R. Sutton

2018-06-01

. Additional determination of acid-labile sulfide/thiols was demonstrated in human blood cells, urine and saliva. Using this simplified mass spectrometry-based workflow the thiol redox metabolome can be determined in samples from clinical and translational studies, providing a novel prognostic/diagnostic platform for patient stratification, drug monitoring, and identification of new therapeutic approaches in redox diseases. Keywords: Oxidative stress, Redox status, Reactive species interactome, Glutathione, Hydrogen sulfide, Persulfides, Thiol-maleimide michael addition

High performance, flexible, poly(3,4-ethylenedioxythiophene) supercapacitors achieved by doping redox mediators in organogel electrolytes

Science.gov (United States)

Zhang, Huanhuan; Li, Jinyu; Gu, Cheng; Yao, Mingming; Yang, Bing; Lu, Ping; Ma, Yuguang

2016-11-01

The relatively low energy density is now a central issue hindering the development of supercapacitors as energy storage devices. Various approaches are thus developed to enhance the energy density, mainly centering on the fabrication of electrode materials or optimization of cell configurations. Compared with these approaches, modifications in electrolytes are much simple and versatile. Herein, we integrate the wide voltages endowed by organic electrolytes and the additional capacitances brought by redox mediators, to fabricate high energy density supercapacitors. On the basis of this idea, supercapacitors with poly(3,4-ethylenedioxythiophene) (PEDOT) as electrode material exhibit extended operating voltage of 1.5 V, extraordinary capacitance of 363 F g-1 and high energy density of 27.4 Wh kg-1. The redox mediators reported here, ferrocene and 4-oxo-2,2,6,6-tetramethylpiperidinooxy, are the first time being applied in supercapacitors, especially in the gel state. While providing additional faradaic capacitances, they also exhibit synergistic interaction with PEDOT and improve the cycling stability of supercapacitors.

The Monte Carlo approach to the economics of a DEMO-like power plant

Energy Technology Data Exchange (ETDEWEB)

Bustreo, Chiara, E-mail: chiara.bustreo@igi.cnr.it; Bolzonella, Tommaso; Zollino, Giuseppe

2015-10-15

Highlights: • A steady state DEMO-like power plant is modelled with the FRESCO code. • The Monte Carlo method is used to assess the probability distribution of the COE. • Uncertainties on technical and economical aspects make the COE vary in a large range. • The COE can be nearly 2/3 to nearly 4 times the cost derived deterministically. - Abstract: An early assessment of the economics of a fusion power plant is a key step to ensure the technology viability in a future global energy system. The FRESCO code is here used to generate the technical, physical and economic model of a steady state DEMO-like power plant whose features are taken from the current European research activities on the DEMO design definition. The Monte Carlo method is used to perform stochastic analyses in order to assess the weight on the cost of electricity of uncertainties on technical and economical aspects. This study demonstrates that a stochastic approach offers a much better perspective over the spectrum of values that could be expected for the cost of electricity from fusion. Specifically, this analysis proves that the cost of electricity of the DEMO-like power plant studied could vary in quite large range, from nearly 2/3 to nearly 4 times the cost derived through a deterministic approach, by choosing reference values for all the stochastic parameters, taken from the literature.

The Project Approach in Organization of Foreign Economic Activity as a Means of Increasing Competitiveness of Industrial Enterprise

Directory of Open Access Journals (Sweden)

Lazarenko Vladimir Ye.

2017-12-01

Full Text Available The article is aimed at studying the organization of foreign economic activity of industrial enterprise in case of introduction of project approach to its management. New conditions of doing business in terms of aircraft building enterprises, consisting in the transition to production according to international standards, require a modern approach to the solution of the range of issues. In conditions of limited internal financial resources of company and high expenses connected with entering the foreign market, it is extremely important to define the priority directions of foreign economic activity and the most optimal mechanisms of its organization and management. The functioning of the sphere of foreign economic activity of industrial enterprise in case of introduction of project approach to management has been analyzed. The essence, features and the main parameters of project approach as a means of increasing the competitiveness of enterprise have been defined. Priorities of the large-scale enterprise development strategy have been analyzed and suggested by means of carrying out the project method of organization of foreign economic activity.

Evaluation of electrolytes for redox flow battery applications

International Nuclear Information System (INIS)

Chakrabarti, M.H.; Dryfe, R.A.W.; Roberts, E.P.L.

2007-01-01

A number of redox systems have been investigated in this work with the aim of identifying electrolytes suitable for testing redox flow battery cell designs. The criteria for the selection of suitable systems were fast electrochemical kinetics and minimal cross-contamination of active electrolytes. Possible electrolyte systems were initially selected based on cyclic voltammetry data. Selected systems were then compared by charge/discharge experiments using a simple H-type cell. The all-vanadium electrolyte system has been developed as a commercial system and was used as the starting point in this study. The performance of the all-vanadium system was significantly better than an all-chromium system which has recently been reported. Some metal-organic and organic redox systems have been reported as possible systems for redox flow batteries, with cyclic voltammetry data suggesting that they could offer near reversible kinetics. However, Ru(acac) 3 in acetonitrile could only be charged efficiently to 9.5% of theoretical charge, after which irreversible side reactions occurred and [Fe(bpy) 3 ](ClO 4 ) 2 in acetonitrile was found to exhibit poor charge/discharge performance

A Membrane‐Free Redox Flow Battery with Two Immiscible Redox Electrolytes

Science.gov (United States)

Navalpotro, Paula; Palma, Jesus; Anderson, Marc

2017-01-01

Abstract Flexible and scalable energy storage solutions are necessary for mitigating fluctuations of renewable energy sources. The main advantage of redox flow batteries is their ability to decouple power and energy. However, they present some limitations including poor performance, short‐lifetimes, and expensive ion‐selective membranes as well as high price, toxicity, and scarcity of vanadium compounds. We report a membrane‐free battery that relies on the immiscibility of redox electrolytes and where vanadium is replaced by organic molecules. We show that the biphasic system formed by one acidic solution and one ionic liquid, both containing quinoyl species, behaves as a reversible battery without any membrane. This proof‐of‐concept of a membrane‐free battery has an open circuit voltage of 1.4 V with a high theoretical energy density of 22.5 Wh L−1, and is able to deliver 90 % of its theoretical capacity while showing excellent long‐term performance (coulombic efficiency of 100 % and energy efficiency of 70 %). PMID:28658538

A Membrane-Free Redox Flow Battery with Two Immiscible Redox Electrolytes.

Science.gov (United States)

Navalpotro, Paula; Palma, Jesus; Anderson, Marc; Marcilla, Rebeca

2017-10-02

Flexible and scalable energy storage solutions are necessary for mitigating fluctuations of renewable energy sources. The main advantage of redox flow batteries is their ability to decouple power and energy. However, they present some limitations including poor performance, short-lifetimes, and expensive ion-selective membranes as well as high price, toxicity, and scarcity of vanadium compounds. We report a membrane-free battery that relies on the immiscibility of redox electrolytes and where vanadium is replaced by organic molecules. We show that the biphasic system formed by one acidic solution and one ionic liquid, both containing quinoyl species, behaves as a reversible battery without any membrane. This proof-of-concept of a membrane-free battery has an open circuit voltage of 1.4 V with a high theoretical energy density of 22.5 Wh L -1 , and is able to deliver 90 % of its theoretical capacity while showing excellent long-term performance (coulombic efficiency of 100 % and energy efficiency of 70 %). © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

In vivo evaluation of different alterations of redox status by studying pharmacokinetics of nitroxides using magnetic resonance techniques

Science.gov (United States)

Bačić, Goran; Pavićević, Aleksandra; Peyrot, Fabienne

2015-01-01

Free radicals, particularly reactive oxygen species (ROS), are involved in various pathologies, injuries related to radiation, ischemia-reperfusion or ageing. Unfortunately, it is virtually impossible to directly detect free radicals in vivo, but the redox status of the whole organism or particular organ can be studied in vivo by using magnetic resonance techniques (EPR and MRI) and paramagnetic stable free radicals – nitroxides. Here we review results obtained in vivo following the pharmacokinetics of nitroxides on experimental animals (and a few in humans) under various conditions. The focus was on conditions where the redox status has been altered by induced diseases or harmful agents, clearly demonstrating that various EPR/MRI/nitroxide combinations can reliably detect metabolically induced changes in the redox status of organs. These findings can improve our understanding of oxidative stress and provide a basis for studying the effectiveness of interventions aimed to modulate oxidative stress. Also, we anticipate that the in vivo EPR/MRI approach in studying the redox status can play a vital role in the clinical management of various pathologies in the years to come providing the development of adequate equipment and probes. PMID:26827126

In vivo evaluation of different alterations of redox status by studying pharmacokinetics of nitroxides using magnetic resonance techniques

Directory of Open Access Journals (Sweden)

Goran Bačić

2016-08-01

Full Text Available Free radicals, particularly reactive oxygen species (ROS, are involved in various pathologies, injuries related to radiation, ischemia-reperfusion or ageing. Unfortunately, it is virtually impossible to directly detect free radicals in vivo, but the redox status of the whole organism or particular organ can be studied in vivo by using magnetic resonance techniques (EPR and MRI and paramagnetic stable free radicals – nitroxides. Here we review results obtained in vivo following the pharmacokinetics of nitroxides on experimental animals (and a few in humans under various conditions. The focus was on conditions where the redox status has been altered by induced diseases or harmful agents, clearly demonstrating that various EPR/MRI/nitroxide combinations can reliably detect metabolically induced changes in the redox status of organs. These findings can improve our understanding of oxidative stress and provide a basis for studying the effectiveness of interventions aimed to modulate oxidative stress. Also, we anticipate that the in vivo EPR/MRI approach in studying the redox status can play a vital role in the clinical management of various pathologies in the years to come providing the development of adequate equipment and probes.

Economic evaluations of pharmacogenetic approaches in infectious diseases: a review of current approaches and evaluation of critical aspects affecting their quality

Directory of Open Access Journals (Sweden)

Paolo Meoni

2013-11-01

Full Text Available Pharmacogenetics holds great potential for improving the effectiveness of treatment modalities in infectious diseases by taking into account the genetic determinants of both the host and infectious agents’ individuality. Better utilization of resources and improved therapeutic efficiency are the expected outcomes of personalized medicine using pharmacogenetic and pharmacogenomics information made available by technological advances. However, there has been growing concern in the clinical community regarding the evaluation of the true benefits of these approaches. This perception is partly due to the limited number and perceived poor quality of economic evaluations in this field, and initiatives aimed at harmonizing and communicating strategies improving the quality of these studies and their acceptance by the clinical community are greatly needed. This paper reviews current literature of economic evaluations of pharmacogenetics interventions guiding pharmacotherapy in infectious diseases. PubMed and the NHS Centre for Reviews and Dissemination databases were searched using a combination of five broad research terms related to pharmacogenetic approaches, and papers relative to economic evaluations of pharmacogenetic interventions in infectious diseases retained for further analysis. Using these criteria, a total of 14 papers were included in this review. The area of economic evaluation of pharmacogenetic interventions in infectious diseases remains understudied and would benefit from greater harmonization. The main weaknesses of evaluations reviewed in this paper seem to be represented by poor evidence of pharmacogenetic marker validation, inconsistencies in the selection of costs and utility included in the economic models and the choice of sensitivity analysis. All these factors limit the overall transparency of the studies, greater acceptance of their results and applicability to diverse and possibly resourcelimited environments where these

[Rational drug use: an economic approach to decision making].

Science.gov (United States)

Mota, Daniel Marques; da Silva, Marcelo Gurgel Carlos; Sudo, Elisa Cazue; Ortún, Vicente

2008-04-01

The present article approaches rational drug use (RDU) from the economical point of view. The implementation of RDU implies in costs and involves acquisition of knowledge and behavioral changes of several agents. The difficulties in implementing RDU may be due to shortage problems, information asymmetry, lack of information, uncertain clinical decisions, externalities, time-price, incentives for drug prescribers and dispensers, drug prescriber preferences and marginal utility. Health authorities, among other agencies, must therefore regularize, rationalize and control drug use to minimize inefficiency in pharmaceutical care and to prevent exposing the population to unnecessary health risks.

Redox Regulation in Amyotrophic Lateral Sclerosis

Science.gov (United States)

Parakh, Sonam; Spencer, Damian M.; Halloran, Mark A.; Soo, Kai Y.; Atkin, Julie D.

2013-01-01

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that results from the death of upper and lower motor neurons. Due to a lack of effective treatment, it is imperative to understand the underlying mechanisms and processes involved in disease progression. Regulations in cellular reduction/oxidation (redox) processes are being increasingly implicated in disease. Here we discuss the possible involvement of redox dysregulation in the pathophysiology of ALS, either as a cause of cellular abnormalities or a consequence. We focus on its possible role in oxidative stress, protein misfolding, glutamate excitotoxicity, lipid peroxidation and cholesterol esterification, mitochondrial dysfunction, impaired axonal transport and neurofilament aggregation, autophagic stress, and endoplasmic reticulum (ER) stress. We also speculate that an ER chaperone protein disulphide isomerase (PDI) could play a key role in this dysregulation. PDI is essential for normal protein folding by oxidation and reduction of disulphide bonds, and hence any disruption to this process may have consequences for motor neurons. Addressing the mechanism underlying redox regulation and dysregulation may therefore help to unravel the molecular mechanism involved in ALS. PMID:23533690

Redox active molecules cytochrome c and vitamin C enhance heme-enzyme peroxidations by serving as non-specific agents for redox relay

International Nuclear Information System (INIS)

Gade, Sudeep Kumar; Bhattacharya, Subarna; Manoj, Kelath Murali

2012-01-01

Highlights: ► At low concentrations, cytochrome c/vitamin C do not catalyze peroxidations. ► But low levels of cytochrome c/vitamin C enhance diverse heme peroxidase activities. ► Enhancement positively correlates to the concentration of peroxide in reaction. ► Reducible additives serve as non-specific agents for redox relay in the system. ► Insight into electron transfer processes in routine and oxidative-stress states. -- Abstract: We report that incorporation of very low concentrations of redox protein cytochrome c and redox active small molecule vitamin C impacted the outcome of one-electron oxidations mediated by structurally distinct plant/fungal heme peroxidases. Evidence suggests that cytochrome c and vitamin C function as a redox relay for diffusible reduced oxygen species in the reaction system, without invoking specific or affinity-based molecular interactions for electron transfers. The findings provide novel perspectives to understanding – (1) the promiscuous role of cytochrome b 5 in the metabolism mediated by liver microsomal xenobiotic metabolizing systems and (2) the roles of antioxidant molecules in affording relief from oxidative stress.

Accelerated redox reaction between chromate and phenolic pollutants during freezing.

Science.gov (United States)

Ju, Jinjung; Kim, Jaesung; Vetráková, Ľubica; Seo, Jiwon; Heger, Dominik; Lee, Changha; Yoon, Ho-Il; Kim, Kitae; Kim, Jungwon

2017-05-05

The redox reaction between 4-chlorophenol (4-CP) and chromate (Cr(VI)) (i.e., the simultaneous oxidation of 4-CP by Cr(VI) and reduction of Cr(VI) by 4-CP) in ice (i.e., at -20°C) was compared with the corresponding reaction in water (i.e., at 25°C). The redox conversion of 4-CP/Cr(VI), which was negligible in water, was significantly accelerated in ice. This accelerated redox conversion of 4-CP/Cr(VI) in ice is ascribed to the freeze concentration effect occurring during freezing, which excludes solutes (i.e., 4-CP and Cr(VI)) and protons from the ice crystals and subsequently concentrates them in the liquid brine. The concentrations of Cr(VI) and protons in the liquid brine were confirmed by measuring the optical image and the UV-vis absorption spectra of cresol red (CR) as a pH indicator of frozen solution. The redox conversion of 4-CP/Cr(VI) was observed in water when the concentrations of 4-CP/protons or Cr(VI)/protons increased by 100/1000-fold. These results corroborate the freeze concentration effect as the reason for the accelerated redox conversion of 4-CP/Cr(VI) in ice. The redox conversion of various phenolic pollutants/Cr(VI) and 4-CP/Cr(VI) in real wastewater was successfully achieved in ice, which verifies the environmental relevance and importance of freezing-accelerated redox conversion of phenolic pollutants/Cr(VI) in cold regions. Copyright © 2017 Elsevier B.V. All rights reserved.

TiO2-photoanode-assisted direct solar energy harvesting and storage in a solar-powered redox cell using halides as active materials.

Science.gov (United States)

Zhang, Shun; Chen, Chen; Zhou, Yangen; Qian, Yumin; Ye, Jing; Xiong, Shiyun; Zhao, Yu; Zhang, Xiaohong

2018-06-19

The rapid deployment of renewable energy is resulting in significant energy security, climate change mitigation, and economic benefits. We demonstrate here the direct solar energy harvesting and storage in a rechargeable solar-powered redox cell, which can be charged solely by solar irradiation. The cell follows a conventional redox-flow cell design with one integrated TiO2 photoanode in the cathode side. Direct charging the cell by solar irradiation results in the conversion of solar energy in to chemical energy. While discharging the cell leads to the release of chemical energy in the form of electricity. The cell integrates energy conversion and storage processes in a single device, making the solar energy directly and efficiently dispatchable. When using redox couples of Br2/Br- and I3-/I- in the cathode side and anode side, respectively, the cell can be directly charged upon solar irradiation, yielding a discharge potential of 0.5V with good round-trip efficiencies. This design is expected to be a potential alternative towards the development of affordable, inexhaustible and clean solar energy technologies.

Iron and Zinc Complexes of Bulky Bis-Imidazole Ligands : Enzyme Mimicry and Ligand-Centered Redox Activity

NARCIS (Netherlands)

Folkertsma, E.

2016-01-01

The research described in this thesis is directed to the development of cheap and non-toxic iron-based homogeneous catalysts, using enzyme models and redox non-innocent ligands. Inspired by nature, the first approach focuses on the synthesis of structural models of the active site of non-heme iron

A risk-economic approach to nuclear power generation. Beyond the myth of absolute safety and unthinkable events

International Nuclear Information System (INIS)

Sakai, Yasuhiro

2012-01-01

This paper deals with a risk-economic approach to nuclear power generation, a very timely yet rather neglected area in the economics profession. The economic and psychological consequences of Japan's recent catastrophe have been so grave and wide-spread, thus calling for careful reexamination of the economics of risk and uncertainty. It is Daniel Bernoulli, a mathematical genius of the 18 th century, who first introduced the expected utility theory into decision making under risk. Although a great deal of applications has been done in many areas since then, it appears that the most recent nuclear meltdown of Japan is casting serious doubt upon the general validity of existing risk theories. It is high time for us to establish a new comprehensive approach by taking account of psychological, sociological, cultural, and historical factors. (author)

Potential redox behaviour on industrial wastes treatment; Evolucion del potencial redox en tratamiento y depuracion industrial de aguas

Energy Technology Data Exchange (ETDEWEB)

Marin Galvin, R.; rodriguez Mellado, J. M.; Ruiz Montoya, M.; Jimenez Gamero, C. [Departamento Quimica Fisica y Termodinamica aplicada, Facultad de ciencias, Universidad de Cordoba (Spain)

1995-12-31

A study over the behaviour of redox potential in waters and wastewaters under industrial treatment processes has been carried out. In both cases, the potential-time curves obtained were in a logarithmical shape being more strongly distorted when the waters contained more dissolved and suspended compounds. Oxygen fundamentally leads the redox state in wastewaters, although ozone and chlorine almost oxygen lead the redox potential in raw waters intended to drinking water production. In this way, by increasing 210 m V the E{sub H} value of water or maintaining the rH>21.8 it can be industrially sterilized the drinking water. On the other hand, increases of 350 mV in the EH values from wastewaters influent to plant to the treated waters, allowed discarding 450 mg/l of DQO and 9 mg/l of NH{sub 3} from the former. Finally, the exploitation of the Wastewaters Treatment Plant by regulation of the E{sub H} values can suppose a good practice. (Author) 14 refs.

Redox pioneer:Professor Christine Helen Foyer.

Science.gov (United States)

Del Río, Luis A

2011-10-15

Dr. Christine Foyer (B.Sc. 1974; Ph.D. 1977) is recognized here as a Redox Pioneer because she has published an article on redox biology that has been cited more than 1000 times, 4 other articles that have been cited more than 500 times, and a further 32 articles that have been each cited more than 100 times. During her Ph.D. at the Kings College, University of London, United Kingdom, Dr. Foyer discovered that ascorbate and glutathione and enzymes linking NADPH, glutathione, and ascorbate are localized in isolated chloroplast preparations. These observations pioneered the discovery of the ascorbate-glutathione cycle, now known as Foyer-Halliwell-Asada pathway after the names of the three major contributors, a crucial mechanism for H(2)O(2) metabolism in both animals and plants. Dr. Foyer has made a very significant contribution to our current understanding of the crucial roles of ascorbate and glutathione in redox biology, particularly in relation to photosynthesis, respiration, and chloroplast and mitochondrial redox signaling networks. "My view is that science…is compulsive and you have to keep with it all the time and not get despondent when things do not work well. Being passionate about science is what carries you through the hard times so that it isn't so much work, as a hobby that you do for a living. It is the thrill of achieving a better understanding and finding real pleasure in putting new ideas together, explaining data and passing on knowledge that keeps you going no matter what!" --Prof. Christine Helen Foyer.

An anaerobic field injection experiment in a landfill leachate plume, Grindsted, Denmark: 2. Deduction of anaerobic (methanogenic, sulfate-, and Fe (III)-reducing) redox conditions

Science.gov (United States)

Albrechtsen, Hans-JøRgen; Bjerg, Poul L.; Ludvigsen, Liselotte; Rügge, Kirsten; Christensen, Thomas H.

1999-04-01

Redox conditions may be environmental factors which affect the fate of the xenobiotic organic compounds. Therefore the redox conditions were characterized in an anaerobic, leachate-contaminated aquifer 15-60 m downgradient from the Grindsted Landfill, Denmark, where an field injection experiment was carried out. Furthermore, the stability of the redox conditions spatially and over time were investigated, and different approaches to deduce the redox conditions were evaluated. The redox conditions were evaluated in a set of 20 sediment and groundwater samples taken from locations adjacent to the sediment samples. Samples were investigated with respect to groundwater chemistry, including hydrogen and volatile fatty acids (VFAs) and sediment geochemistry, and bioassays were performed. The groundwater chemistry, including redox sensitive species for a large number of samples, varied over time during the experimental period of 924 days owing to variations in the leachate from the landfill. However, no indication of change in the redox environment resulting from the field injection experiment or natural variation was observed in the individual sampling points. The methane, Fe(II), hydrogen, and VFA groundwater chemistry parameters strongly indicated a Fe(III)-reducing environment. This was further supported by the bioassays, although methane production and sulfate-reduction were also observed in a few samples close to the landfill. On the basis of the calculated carbon conversion, Fe(III) was the dominant electron acceptor in the region of the aquifer, which was investigated. Because of the complexity of a landfill leachate plume, several redox processes may occur simultaneously, and an array of methods must be applied for redox characterization in such multicomponent systems.

Differentiating cancerous from normal breast tissue by redox imaging

Science.gov (United States)

Xu, He N.; Tchou, Julia; Feng, Min; Zhao, Huaqing; Li, Lin Z.

2015-02-01

Abnormal metabolism can be a hallmark of cancer occurring early before detectable histological changes and may serve as an early detection biomarker. The current gold standard to establish breast cancer (BC) diagnosis is histological examination of biopsy. Previously we have found that pre-cancer and cancer tissues in animal models displayed abnormal mitochondrial redox state. Our technique of quantitatively measuring the mitochondrial redox state has the potential to be implemented as an early detection tool for cancer and may provide prognostic value. We therefore in this present study, investigated the feasibility of quantifying the redox state of tumor samples from 16 BC patients. Tumor tissue aliquots were collected from both normal and cancerous tissue from the affected cancer-bearing breasts of 16 female patients (5 TNBC, 9 ER+, 2 ER+/Her2+) shortly after surgical resection. All specimens were snap-frozen with liquid nitrogen on site and scanned later with the Chance redox scanner, i.e., the 3D cryogenic NADH/oxidized flavoprotein (Fp) fluorescence imager. Our preliminary results showed that both NADH and Fp (including FAD, i.e., flavin adenine dinucleotide) signals in the cancerous tissues roughly tripled to quadrupled those in the normal tissues (pcancerous tissues than in the normal ones (pcancer and non-cancer breast tissues in human patients and this novel redox scanning procedure may assist in tissue diagnosis in freshly procured biopsy samples prior to tissue fixation. We are in the process of evaluating the prognostic value of the redox imaging indices for BC.

Characterization of plasma thiol redox potential in a common marmoset model of aging

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James R. Roede

2013-01-01

Full Text Available Due to its short lifespan, ease of use and age-related pathologies that mirror those observed in humans, the common marmoset (Callithrix jacchus is poised to become a standard nonhuman primate model of aging. Blood and extracellular fluid possess two major thiol-dependent redox nodes involving cysteine (Cys, cystine (CySS, glutathione (GSH and glutathione disulfide (GSSG. Alteration in these plasma redox nodes significantly affects cellular physiology, and oxidation of the plasma Cys/CySS redox potential (EhCySS is associated with aging and disease risk in humans. The purpose of this study was to determine age-related changes in plasma redox metabolites and corresponding redox potentials (Eh to further validate the marmoset as a nonhuman primate model of aging. We measured plasma thiol redox states in marmosets and used existing human data with multivariate adaptive regression splines (MARS to model the relationships between age and redox metabolites. A classification accuracy of 70.2% and an AUC of 0.703 were achieved using the MARS model built from the marmoset redox data to classify the human samples as young or old. These results show that common marmosets provide a useful model for thiol redox biology of aging.

TAX COMPOSITION AND ECONOMIC GROWTH. A PANEL-MODEL APPROACH FOR EASTERN EUROPE

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MURA PETRU-OVIDIU

2015-03-01

Full Text Available In this paper, we investigate the impact of tax composition on economic growth, based on a panel-model approach. The dataset includes six East-European countries and covers the period 1995-2012. Specifically, the study explores the relative impact of different components of tax revenue (direct and indirect tax revenue, as percentage of total tax revenue on economic growth. The paper adds marginally to the empirical literature, showing how the two types of tax revenue influence economic growth in Eastern Europe, under an extended set of economic and sociopolitical control variables. The most important empirical output, for the 6 investigated East-European countries during 1995-2012, suggests that direct taxes are significant and negatively correlated with economic growth, while indirect taxes exert a positive influence on the dependent variable, though insignificant. As for the control variables, it seems that only freedom from corruption and political stability have a significant impact on economic growth. The study suggests that the design of tax systems in Eastern European countries is in accordance with the Commission’s priorities regarding its growth-friendliness. As for policy implications, governments should continue shifting the tax burden away from labour on to tax bases linked to consumption, property, and combating pollution, with potential positive effects both for growth and for fighting against tax evasion.

A novel iron-lead redox flow battery for large-scale energy storage

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Zeng, Y. K.; Zhao, T. S.; Zhou, X. L.; Wei, L.; Ren, Y. X.

2017-04-01

The redox flow battery (RFB) is one of the most promising large-scale energy storage technologies for the massive utilization of intermittent renewables especially wind and solar energy. This work presents a novel redox flow battery that utilizes inexpensive and abundant Fe(II)/Fe(III) and Pb/Pb(II) redox couples as redox materials. Experimental results show that both the Fe(II)/Fe(III) and Pb/Pb(II) redox couples have fast electrochemical kinetics in methanesulfonic acid, and that the coulombic efficiency and energy efficiency of the battery are, respectively, as high as 96.2% and 86.2% at 40 mA cm-2. Furthermore, the battery exhibits stable performance in terms of efficiencies and discharge capacities during the cycle test. The inexpensive redox materials, fast electrochemical kinetics and stable cycle performance make the present battery a promising candidate for large-scale energy storage applications.

The Redox Flow System for solar photovoltaic energy storage

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Odonnell, P.; Gahn, R. F.; Pfeiffer, W.

1976-01-01

The interfacing of a Solar Photovoltaic System and a Redox Flow System for storage was workable. The Redox Flow System, which utilizes the oxidation-reduction capability of two redox couples, in this case iron and titanium, for its storage capacity, gave a relatively constant output regardless of solar activity so that a load could be run continually day and night utilizing the sun's energy. One portion of the system was connected to a bank of solar cells to electrochemically charge the solutions, while a separate part of the system was used to electrochemically discharge the stored energy.

High-energy-density, aqueous, metal-polyiodide redox flow batteries

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Li, Bin; Nie, Zimin; Wang, Wei; Liu, Jun; Sprenkle, Vincent L.

2017-08-29

Improved metal-based redox flow batteries (RFBs) can utilize a metal and a divalent cation of the metal (M.sup.2+) as an active redox couple for a first electrode and electrolyte, respectively, in a first half-cell. For example, the metal can be Zn. The RFBs can also utilize a second electrolyte having I.sup.-, anions of I.sub.x (for x.gtoreq.3), or both in an aqueous solution, wherein the I.sup.- and the anions of I.sub.x (for x.gtoreq.3) compose an active redox couple in a second half-cell.

The Analgesic Acetaminophen and the Antipsychotic Clozapine Can Each Redox-Cycle with Melanin.

Science.gov (United States)

Temoçin, Zülfikar; Kim, Eunkyoung; Li, Jinyang; Panzella, Lucia; Alfieri, Maria Laura; Napolitano, Alessandra; Kelly, Deanna L; Bentley, William E; Payne, Gregory F

2017-12-20

Melanins are ubiquitous but their complexity and insolubility has hindered characterization of their structures and functions. We are developing electrochemical reverse engineering methodologies that focus on properties and especially on redox properties. Previous studies have shown that melanins (i) are redox-active and can rapidly and repeatedly exchange electrons with diffusible oxidants and reductants, and (ii) have redox potentials in midregion of the physiological range. These properties suggest the functional activities of melanins will depend on their redox context. The brain has a complex redox context with steep local gradients in O 2 that can promote redox-cycling between melanin and diffusible redox-active chemical species. Here, we performed in vitro reverse engineering studies and report that melanins can redox-cycle with two common redox-active drugs. Experimentally, we used two melanin models: a convenient natural melanin derived from cuttlefish (Sepia melanin) and a synthetic cysteinyldopamine-dopamine core-shell model of neuromelanin. One drug, acetaminophen (APAP), has been used clinically for over a century, and recent studies suggest that low doses of APAP can protect the brain from oxidative-stress-induced toxicity and neurodegeneration, while higher doses can have toxic effects in the brain. The second drug, clozapine (CLZ), is a second generation antipsychotic with polypharmacological activities that remain incompletely understood. These in vitro observations suggest that the redox activities of drugs may be relevant to their modes-of-action, and that melanins may interact with drugs in ways that affect their activities, metabolism, and toxicities.

Redox regulation of the Calvin-Benson cycle: something old, something new

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Laure eMichelet

2013-11-01

Full Text Available Reversible redox post-translational modifications such as oxido-reduction of disulfide bonds, S-nitrosylation and S-glutathionylation, play a prominent role in the regulation of cell metabolism and signaling in all organisms. These modifications are mainly controlled by members of the thioredoxin and glutaredoxin families. Early studies in photosynthetic organisms have identified the Calvin-Benson cycle, the photosynthetic pathway responsible for carbon assimilation, as a redox regulated process. Indeed, 4 out of 11 enzymes of the cycle were shown to have a low activity in the dark and to be activated in the light through thioredoxin-dependent reduction of regulatory disulfide bonds. The underlying molecular mechanisms were extensively studied at the biochemical and structural level. Unexpectedly, recent biochemical and proteomic studies have suggested that all enzymes of the cycle and several associated regulatory proteins may undergo redox regulation through multiple redox post-translational modifications including glutathionylation and nitrosylation. The aim of this review is to detail the well-established mechanisms of redox regulation of Calvin-Benson cycle enzymes as well as the most recent reports indicating that this pathway is tightly controlled by multiple interconnected redox post-translational modifications. This redox control is likely allowing fine tuning of the Calvin-Benson cycle required for adaptation to varying environmental conditions, especially during responses to biotic and abiotic stresses.

The redox biology network in cancer pathophysiology and therapeutics

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Gina Manda

2015-08-01

Full Text Available The review pinpoints operational concepts related to the redox biology network applied to the pathophysiology and therapeutics of solid tumors. A sophisticated network of intrinsic and extrinsic cues, integrated in the tumor niche, drives tumorigenesis and tumor progression. Critical mutations and distorted redox signaling pathways orchestrate pathologic events inside cancer cells, resulting in resistance to stress and death signals, aberrant proliferation and efficient repair mechanisms. Additionally, the complex inter-cellular crosstalk within the tumor niche, mediated by cytokines, redox-sensitive danger signals (HMGB1 and exosomes, under the pressure of multiple stresses (oxidative, inflammatory, metabolic, greatly contributes to the malignant phenotype. The tumor-associated inflammatory stress and its suppressive action on the anti-tumor immune response are highlighted. We further emphasize that ROS may act either as supporter or enemy of cancer cells, depending on the context. Oxidative stress-based therapies, such as radiotherapy and photodynamic therapy, take advantage of the cytotoxic face of ROS for killing tumor cells by a non-physiologically sudden, localized and intense oxidative burst. The type of tumor cell death elicited by these therapies is discussed. Therapy outcome depends on the differential sensitivity to oxidative stress of particular tumor cells, such as cancer stem cells, and therefore co-therapies that transiently down-regulate their intrinsic antioxidant system hold great promise. We draw attention on the consequences of the damage signals delivered by oxidative stress-injured cells to neighboring and distant cells, and emphasize the benefits of therapeutically triggered immunologic cell death in metastatic cancer. An integrative approach should be applied when designing therapeutic strategies in cancer, taking into consideration the mutational, metabolic, inflammatory and oxidative status of tumor cells, cellular

The economic approach to the problem of tax evasion and recommendations for Serbia

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Milosavljević Valentina

2016-01-01

Full Text Available Tax evasion is a global problem and it has severe consequences for every country, regardless of differences in socio-economic and political structure. The basis for tax criminal offenses is embodied in different manifestations of tax evasion, especially when taking into account that tax evasion is also the most important form of informal economy. Since the taxation achieves not only fiscal, but also objectives in the field of economic and social policy, tax evasion has consequences on the economic and socio-political level. After introductory considerations, the paper shows the topicality of this issue, then the analysis of theoretical and practical features of tax evasion, as the basic fiscal criminal offense in the new Criminal Law of the Republic of Serbia, while the economic approach to the problem of tax evasion is based on an analysis of individual behavior of taxpayers.

TEMPO/viologen electrochemical heterojunction for diffusion-controlled redox mediation: a highly rectifying bilayer-sandwiched device based on cross-reaction at the interface between dissimilar redox polymers.

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Tokue, Hiroshi; Oyaizu, Kenichi; Sukegawa, Takashi; Nishide, Hiroyuki

2014-03-26

A couple of totally reversible redox-active molecules, which are different in redox potentials, 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) and viologen (V(2+)), were employed to give rise to a rectified redox conduction effect. Single-layer and bilayer devices were fabricated using polymers containing these sites as pendant groups per repeating unit. The devices were obtained by sandwiching the redox polymer layer(s) with indium tin oxide (ITO)/glass and Pt foil electrodes. Electrochemical measurements of the single-layer device composed of polynorbornene-bearing TEMPO (PTNB) exhibited a diffusion-limited current-voltage response based on the TEMPO(+)/TEMPO exchange reaction, which was almost equivalent to a redox gradient through the PTNB layer depending upon the thickness. The bilayer device gave rise to the current rectification because of the thermodynamically favored cross-reaction between TEMPO(+) and V(+) at the polymer/polymer interface. A current-voltage response obtained for the bilayer device demonstrated a two-step diffusion-limited current behavior as a result of the concurrent V(2+)/V(+) and V(+)/V(0) exchange reactions according to the voltage and suggested that the charge transport process through the device was most likely to be rate-determined by a redox gradient in the polymer layer. Current collection experiments revealed a charge transport balance throughout the device, as a result of the electrochemical stability and robustness of the polymers in both redox states.

Anionic Redox Chemistry in Polysulfide Electrode Materials for Rechargeable Batteries.

Science.gov (United States)

Grayfer, Ekaterina D; Pazhetnov, Egor M; Kozlova, Mariia N; Artemkina, Sofya B; Fedorov, Vladimir E

2017-12-22

Classical Li-ion battery technology is based on the insertion of lithium ions into cathode materials involving metal (cationic) redox reactions. However, this vision is now being reconsidered, as many new-generation electrode materials with enhanced reversible capacities operate through combined cationic and anionic (non-metal) reversible redox processes or even exclusively through anionic redox transformations. Anionic participation in the redox reactions is observed in materials with more pronounced covalency, which is less typical for oxides, but quite common for phosphides or chalcogenides. In this Concept, we would like to draw the reader's attention to this new idea, especially, as it applies to transition-metal polychalcogenides, such as FeS 2 , VS 4 , TiS 3 , NbS 3 , TiS 4 , MoS 3 , etc., in which the key role is played by the (S-S) 2- /2 S 2- redox reaction. The exploration and better understanding of the anion-driven chemistry is important for designing advanced materials for battery and other energy-related applications. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mechanisms of redox metabolism and cancer cell survival during extracellular matrix detachment.

Science.gov (United States)

Hawk, Mark A; Schafer, Zachary T

2018-01-16

Non-transformed cells that become detached from the extracellular matrix (ECM) undergo dysregulation of redox homeostasis and cell death. In contrast, cancer cells often acquire the ability to mitigate programmed cell death pathways and recalibrate the redox balance to survive after ECM detachment, facilitating metastatic dissemination. Accordingly, recent studies of the mechanisms by which cancer cells overcome ECM detachment-induced metabolic alterations have focused on mechanisms in redox homeostasis. The insights into these mechanisms may inform the development of therapeutics that manipulate redox homeostasis to eliminate ECM-detached cancer cells. Here, we review how ECM-detached cancer cells balance redox metabolism for survival. Published under license by The American Society for Biochemistry and Molecular Biology, Inc.

4"t"h Annual workshop proceedings of the collaborative project ''Redox phenomena controlling systems'' (7"t"h EC FP CP RECOSY)

International Nuclear Information System (INIS)

Altmaier, Marcus; Kienzler, Bernhard; Duro, Lara; Grive, Mireia; Montoya, Vanessa

2012-01-01

The EURATOM 7"t"h EC Framework Program Collaborative Project REdox phenomena Controlling SYstems (RECOSY) started in April 2008 and extends over 4 years. Although redox is not a new geochemical issue, different questions are still not resolved. For this reason, main objectives of RECOSY project are a) the sound understanding of redox phenomena controlling the long-term release/retention of radionuclides in nuclear waste disposal, b) providing tools to apply the result to Performance Assessment/Safety Case, c) training of next generation and d) documentation and communication of the results. To this aim, the project set up a consortium of 32 Beneficiaries/Contractors and 6 Associated Groups. The consortium includes key European Research Institutes, Universities, National Waste Management Agencies and SMEs, from 13 EURATOM signatory states, Russia, Japan, Korea, USA and one European Joint Research Centre. The ReCosy concept is innovative in the scientific approach to the redox phenomena. It includes i) advanced analytical tools, ii) investigations of processes responsible for redox control (thermodynamically and kinetically controlled processes, surface reactions and microbial processes,..), iii) provision of required data on redox controlling processes, and iv) response to disturbances in disposal systems. The work program is structured along six RTD workpackages (WP1-6). They cover near-field and far field aspects as well as all relevant host-rocks considered in Europe. In WP1, the scientific state-of-the-art and its application to Performance Assessment/Safety Case is documented and regularly updated. WP2 focuses on development of redox determination methods. WP3 focuses on redox response of defined and near-natural systems. WP4 studies the redox reactions of radionuclides. WP5 focuses on Redox processes in radionuclide transport and WP6 deals with redox reactions affecting the spent fuel source-term. Specific workpackages on knowledge management, education and

A simple, fast and accurate in-situ method to measure the rate of transport of redox species through membranes for lithium batteries

Science.gov (United States)

Meddings, Nina; Owen, John R.; Garcia-Araez, Nuria

2017-10-01

Lithium ion conducting membranes are important to protect the lithium metal electrode and act as a barrier to crossover species such as polysulphides in Li-S systems, redox mediators in Li-O2 cells or dissolved cathode species or electrolyte oxidation products in high voltage Li-ion batteries. We present an in-situ method for measuring permeability of membranes to crossover redox species. The method employs a 'Swagelok' cell design equipped with a glassy carbon working electrode, in which redox species are placed initially in the counter electrode compartment only. Permeability through the membrane, which separates working and counter electrodes, is determined using a square wave voltammetry technique that allows the concentration of crossover redox species to be evaluated over time with very high precision. We test the method using a model and well-behaved electrochemical system to demonstrate its sensitivity, reproducibility and reliability relative to alternative approaches. This new method offers advantages in terms of small electrolyte volume, and simple, fast, quantitative and in-situ measurement.

Differential alkylation-based redox proteomics--Lessons learnt.

Science.gov (United States)

Wojdyla, Katarzyna; Rogowska-Wrzesinska, Adelina

2015-12-01

Cysteine is one of the most reactive amino acids. This is due to the electronegativity of sulphur atom in the side chain of thiolate group. It results in cysteine being present in several distinct redox forms inside the cell. Amongst these, reversible oxidations, S-nitrosylation and S-sulfenylation are crucial mediators of intracellular redox signalling, with known associations to health and disease. Study of their functionalities has intensified thanks to the development of various analytical strategies, with particular contribution from differential alkylation-based proteomics methods. Presented here is a critical evaluation of differential alkylation-based strategies for the analysis of S-nitrosylation and S-sulfenylation. The aim is to assess the current status and to provide insights for future directions in the dynamically evolving field of redox proteomics. To achieve that we collected 35 original research articles published since 2010 and analysed them considering the following parameters, (i) resolution of modification site, (ii) quantitative information, including correction of modification levels by protein abundance changes and determination of modification site occupancy, (iii) throughput, including the amount of starting material required for analysis. The results of this meta-analysis are the core of this review, complemented by issues related to biological models and sample preparation in redox proteomics, including conditions for free thiol blocking and labelling of target cysteine oxoforms. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Graphite-graphite oxide composite electrode for vanadium redox flow battery

International Nuclear Information System (INIS)

Li Wenyue; Liu Jianguo; Yan Chuanwei

2011-01-01

Highlights: → A new composite electrode is designed for vanadium redox flow battery (VRB). → The graphite oxide (GO) is used as electrode reactions catalyst. → The excellent electrode activity is attributed to the oxygen-containing groups attached on the GO surface. → A catalytic mechanism of the GO towards the redox reactions is presumed. - Abstract: A graphite/graphite oxide (GO) composite electrode for vanadium redox battery (VRB) was prepared successfully in this paper. The materials were characterized with X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. The specific surface area was measured by the Brunauer-Emmett-Teller method. The redox reactions of [VO 2 ] + /[VO] 2+ and V 3+ /V 2+ were studied with cyclic voltammetry and electrochemical impedance spectroscopy. The results indicated that the electrochemical performances of the electrode were improved greatly when 3 wt% GO was added into graphite electrode. The redox peak currents of [VO 2 ] + /[VO] 2+ and V 3+ /V 2+ couples on the composite electrode were increased nearly twice as large as that on the graphite electrode, and the charge transfer resistances of the redox pairs on the composite electrode are also reduced. The enhanced electrochemical activity could be ascribed to the presence of plentiful oxygen functional groups on the basal planes and sheet edges of the GO and large specific surface areas introduced by the GO.

Porphyrin-Based Symmetric Redox-Flow Batteries towards Cold-Climate Energy Storage.

Science.gov (United States)

Ma, Ting; Pan, Zeng; Miao, Licheng; Chen, Chengcheng; Han, Mo; Shang, Zhenfeng; Chen, Jun

2018-03-12

Electrochemical energy storage with redox-flow batteries (RFBs) under subzero temperature is of great significance for the use of renewable energy in cold regions. However, RFBs are generally used above 10 °C. Herein we present non-aqueous organic RFBs based on 5,10,15,20-tetraphenylporphyrin (H 2 TPP) as a bipolar redox-active material (anode: [H 2 TPP] 2- /H 2 TPP, cathode: H 2 TPP/[H 2 TPP] 2+ ) and a Y-zeolite-poly(vinylidene fluoride) (Y-PVDF) ion-selective membrane with high ionic conductivity as a separator. The constructed RFBs exhibit a high volumetric capacity of 8.72 Ah L -1 with a high voltage of 2.83 V and excellent cycling stability (capacity retention exceeding 99.98 % per cycle) in the temperature range between 20 and -40 °C. Our study highlights principles for the design of RFBs that operate at low temperatures, thus offering a promising approach to electrochemical energy storage under cold-climate conditions. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

The self-assembly of redox active peptides: Synthesis and electrochemical capacitive behavior.

Science.gov (United States)

Piccoli, Julia P; Santos, Adriano; Santos-Filho, Norival A; Lorenzón, Esteban N; Cilli, Eduardo M; Bueno, Paulo R

2016-05-01

The present work reports on the synthesis of a redox-tagged peptide with self-assembling capability aiming applications in electrochemically active capacitive surfaces (associated with the presence of the redox centers) generally useful in electroanalytical applications. Peptide containing ferrocene (fc) molecular (redox) group (Ac-Cys-Ile-Ile-Lys(fc)-Ile-Ile-COOH) was thus synthesized by solid phase peptide synthesis (SPPS). To obtain the electrochemically active capacitive interface, the side chain of the cysteine was covalently bound to the gold electrode (sulfur group) and the side chain of Lys was used to attach the ferrocene in the peptide chain. After obtaining the purified redox-tagged peptide, the self-assembly and redox capability was characterized by cyclic voltammetry (CV) and electrochemical impedance-based capacitance spectroscopy techniques. The obtained results confirmed that the redox-tagged peptide was successfully attached by forming an electroactive self-assembled monolayer onto gold electrode. The design of redox active self-assembly ferrocene-tagged peptide is predictably useful in the development of biosensor devices precisely to detect, in a label-free platform, those biomarkers of clinical relevance. © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 357-367, 2016. © 2016 Wiley Periodicals, Inc.

Mutagenesis of the redox-active disulfide in mercuric ion reductase: Catalysis by mutant enzymes restricted to flavin redox chemistry

International Nuclear Information System (INIS)

Distefano, M.D.; Au, K.G.; Walsh, C.T.

1989-01-01

Mercuric reductase, a flavoenzyme that possesses a redox-active cystine, Cys 135 Cys 140 , catalyzes the reduction of Hg(II) to Hg(0) by NADPH. As a probe of mechanism, the authors have constructed mutants lacking a redox-active disulfide by eliminating Cys 135 (Ala 135 Cys 140 ), Cys 14 (Cys 135 Ala 140 ), or both (Ala 135 Ala 140 ). Additionally, they have made double mutants that lack Cys 135 (Ala 135 Cys 139 Cys 140 ) or Cys 140 (Cys 135 Cys 139 Ala 140 ) but introduce a new Cys in place of Gly 139 with the aim of constructing dithiol pairs in the active site that do not form a redox-active disulfide. The resulting mutant enzymes all lack redox-active disulfides and are hence restricted to FAD/FADH 2 redox chemistry. Each mutant enzyme possesses unique physical and spectroscopic properties that reflect subtle differences in the FAD microenvironment. Preliminary evidence for the Ala 135 Cys 139 Cys 14 mutant enzyme suggests that this protein forms a disulfide between the two adjacent Cys residues. Hg(II) titration experiments that correlate the extent of charge-transfer quenching with Hg(II) binding indicate that the Ala 135 Cys 140 protein binds Hg(II) with substantially less avidity than does the wild-type enzyme. All mutant mercuric reductases catalyze transhydrogenation and oxygen reduction reactions through obligatory reduced flavin intermediates at rates comparable to or greater than that of the wild-type enzyme. In multiple-turnover assays which monitored the production of Hg(0), two of the mutant enzymes were observed to proceed through at least 30 turnovers at rates ca. 1000-fold slower than that of wild-type mercuric reductase. They conclude that the Cys 135 and Cys 140 thiols serve as Hg(II) ligands that orient the Hg(II) for subsequent reduction by a reduced flavin intermediate

Direct determination of the redox status of cysteine residues in proteins in vivo

Energy Technology Data Exchange (ETDEWEB)

Hara, Satoshi [Chemical Resources Laboratory, Tokyo Institute of Technology, Nagatsuta 4259-R1-8, Midori-ku, Yokohama 226-8503 (Japan); Tatenaka, Yuki; Ohuchi, Yuya [Dojindo Laboratories, 2025-5 Tabaru, Mashiki-machi, Kumamoto 861-2202 (Japan); Hisabori, Toru, E-mail: thisabor@res.titech.ac.jp [Chemical Resources Laboratory, Tokyo Institute of Technology, Nagatsuta 4259-R1-8, Midori-ku, Yokohama 226-8503 (Japan); Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Tokyo 102-0075 (Japan)

2015-01-02

Highlights: • A new DNA-maleimide which is cleaved by UV irradiation, DNA-PCMal, was developed. • DNA-PCMal can be used like DNA-Mal to analyze the redox state of cysteine residues. • It is useful for detecting the thiol redox status of a protein in vivo by Western blotting method. • Thus, DNA-PCMal can be a powerful tool for redox proteomics analysis. - Abstract: The redox states of proteins in cells are key factors in many cellular processes. To determine the redox status of cysteinyl thiol groups in proteins in vivo, we developed a new maleimide reagent, a photocleavable maleimide-conjugated single stranded DNA (DNA-PCMal). The DNA moiety of DNA-PCMal is easily removed by UV-irradiation, allowing DNA-PCMal to be used in Western blotting applications. Thereby the state of thiol groups in intracellular proteins can be directly evaluated. This new maleimide compound can provide information concerning redox proteins in vivo, which is important for our understanding of redox networks in the cell.

Intramolecular Redox-Mannich Reactions: Facile Access to the Tetrahydroprotoberberine Core.

Science.gov (United States)

Ma, Longle; Seidel, Daniel

2015-09-07

Cyclic amines such as pyrrolidine undergo redox-annulations with 2-formylaryl malonates. Concurrent oxidative amine α-CH bond functionalization and reductive N-alkylation render this transformation redox-neutral. This redox-Mannich process provides regioisomers of classic Reinhoudt reaction products as an entry to the tetrahydroprotoberberine core, enabling the synthesis of (±)-thalictricavine and its epimer. An unusually mild amine-promoted dealkoxycarbonylation was discovered in the course of these studies. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Actin filaments – a target for redox regulation

Science.gov (United States)

Wilson, Carlos; Terman, Jonathan R.; González-Billault, Christian; Ahmed, Giasuddin

2016-01-01

Actin and its ability to polymerize into dynamic filaments is critical for the form and function of cells throughout the body. While multiple proteins have been characterized as affecting actin dynamics through non-covalent means, actin and its protein regulators are also susceptible to covalent modifications of their amino acid residues. In this regard, oxidation-reduction (Redox) intermediates have emerged as key modulators of the actin cytoskeleton with multiple different effects on cellular form and function. Here, we review work implicating Redox intermediates in post-translationally altering actin and discuss what is known regarding how these alterations affect the properties of actin. We also focus on two of the best characterized enzymatic sources of these Redox intermediates – the NADPH oxidase NOX and the flavoprotein monooxygenase MICAL – and detail how they have both been identified as altering actin, but share little similarity and employ different means to regulate actin dynamics. Finally, we discuss the role of these enzymes and redox signaling in regulating the actin cytoskeleton in vivo and highlight their importance for neuronal form and function in health and disease. PMID:27309342

The redox-Mannich reaction.

Science.gov (United States)

Chen, Weijie; Seidel, Daniel

2014-06-06

A complement to the classic three-component Mannich reaction, the redox-Mannich reaction, utilizes the same starting materials but incorporates an isomerization step that enables the facile preparation of ring-substituted β-amino ketones. Reactions occur under relatively mild conditions and are facilitated by benzoic acid.

Redox Impact on Starch Biosynthetic Enzymes in Arabidopsis thaliana

DEFF Research Database (Denmark)

Skryhan, Katsiaryna

Summary The thesis provides new insight into the influence of the plant cell redox state on the transient starch metabolism in Arabidopsis thaliana with a focus on starch biosynthetic enzymes. Two main hypotheses forms the basis of this thesis: 1) photosynthesis and starch metabolism are coordina......Summary The thesis provides new insight into the influence of the plant cell redox state on the transient starch metabolism in Arabidopsis thaliana with a focus on starch biosynthetic enzymes. Two main hypotheses forms the basis of this thesis: 1) photosynthesis and starch metabolism...... are coordinated by the redox state of the cell via post-translational modification of the starch metabolic enzymes containing redox active cysteine residues and these cysteine residues became cross-linked upon oxidation providing a conformational change leading to activity loss; 2) cysteine residues...... of chloroplast enzymes can play a role not only in enzyme activity and redox sensitivity but also in protein folding and stability upon oxidation. Several redox sensitive enzymes identified in this study can serve as potential targets to control the carbon flux to and from starch during the day and night...

Effect of organic additives on positive electrolyte for vanadium redox battery

International Nuclear Information System (INIS)

Li Sha; Huang Kelong; Liu Suqin; Fang Dong; Wu Xiongwei; Lu Dan; Wu Tao

2011-01-01

Highlights: → Four organics as electrolyte additives of vanadium redox battery. → Changes are examined in the electrochemical properties of vanadium redox battery. → D-sorbitol is a suitable additive to the electrolyte for the vanadium redox battery. → The mechanism of improvement is discussed in detail. - Abstract: Fructose, mannitol, glucose, D-sorbitol are explored as additives in electrolyte for vanadium redox battery (VRB), respectively. The effects of additives on electrolyte are studied by cyclic voltammetry (CV), charge-discharge technique, electrochemical impedance spectroscopy (EIS) and Raman spectroscopy. The results indicate that the vanadium redox cell using the electrolyte with the additive of D-sorbitol exhibits the best electrochemical performance (the energy efficiency 81.8%). The EIS results indicate that the electrochemical activity of the electrolyte is improved by adding D-sorbitol, which can be interpreted as the increase of available (-OH) groups providing active sites for electron transfer. The Raman spectra show that VO 2+ ions take part in forming a complex with the D-sorbitol, which not only improve solubility of V(V) electrolyte, but also provide more activity sites for the V(IV)/V(V) redox reaction.

Effect of organic additives on positive electrolyte for vanadium redox battery

Energy Technology Data Exchange (ETDEWEB)

Li Sha [Department of Functional Materials and Chemistry, School of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Huang Kelong, E-mail: lisha_csu@163.com [Department of Functional Materials and Chemistry, School of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Liu Suqin; Fang Dong; Wu Xiongwei; Lu Dan; Wu Tao [Department of Functional Materials and Chemistry, School of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China)

2011-06-30

Highlights: > Four organics as electrolyte additives of vanadium redox battery. > Changes are examined in the electrochemical properties of vanadium redox battery. > D-sorbitol is a suitable additive to the electrolyte for the vanadium redox battery. > The mechanism of improvement is discussed in detail. - Abstract: Fructose, mannitol, glucose, D-sorbitol are explored as additives in electrolyte for vanadium redox battery (VRB), respectively. The effects of additives on electrolyte are studied by cyclic voltammetry (CV), charge-discharge technique, electrochemical impedance spectroscopy (EIS) and Raman spectroscopy. The results indicate that the vanadium redox cell using the electrolyte with the additive of D-sorbitol exhibits the best electrochemical performance (the energy efficiency 81.8%). The EIS results indicate that the electrochemical activity of the electrolyte is improved by adding D-sorbitol, which can be interpreted as the increase of available (-OH) groups providing active sites for electron transfer. The Raman spectra show that VO{sup 2+} ions take part in forming a complex with the D-sorbitol, which not only improve solubility of V(V) electrolyte, but also provide more activity sites for the V(IV)/V(V) redox reaction.

An application of actinide elements for a redox flow battery

International Nuclear Information System (INIS)

Shiokawa, Yoshinobu; Yamana, Hajimu; Moriyama, Hirotake

2000-01-01

The electrochemical properties of U, Np, Pu and Am were discussed from the viewpoint of cell active materials. From the thermodynamic properties and the kinetics of electrode reactions, it is found that neptunium in the aqueous system can be utilized as an active material of the redox flow battery for the electric power storage. A new neptunium redox battery is proposed in the present article: the galvanic cell is expressed by (-)|Np 3+ , Np 4+ |NpO 2 + , NpO 2 2+ |(+). The neptunium battery is expected to have more excellent charge and discharge performance than the current vanadium battery, whereas the thermodynamic one of the former is comparable to the latter. For the development of a uranium redox battery, the application of the redox reactions in the non-aqueous solvents is essential. (author)

The International intraval project. Phase 1, case 7. The Pocos de Caldas natural analogue: studies of redox front movement

International Nuclear Information System (INIS)

Chapman, N.

1992-01-01

The study of natural analogues is an important means of validating models of the geochemical processes affecting radionuclide behaviour. This test case, which is one aspect taken from the much broader geochemical studies carried out in the Pocos de Caldas Project, concerns the nature and behaviour of redox fronts, such as might be generated in the near-field of a spent-fuel repository. A redox front is potentially important in terms of the movements and speciation of certain radionuclides close to the waste package. The natural redox fronts in Osamu Utsumi uranium mine display many of the features which may occur in a repository, and influence the movement of natural series radionuclides, and other elements, through the rock/groundwater system. This report, describes the geological, hydrogeological and geochemical nature of the site, and of the redox fronts. Emphasis is placed on the mineralogy of the fronts, and the concentration profiles of various elements across them. The project involved a number of different modelling approaches which attempted to describe the generation and movement of the fronts through the rock. These included mass balance, reaction-diffusion models, fissure flow models, thermodynamic models, and kinetic models. 21 refs., 36 figs., 1 tab

The fairytale of the GSSG/GSH redox potential.

Science.gov (United States)

Flohé, Leopold

2013-05-01

The term GSSG/GSH redox potential is frequently used to explain redox regulation and other biological processes. The relevance of the GSSG/GSH redox potential as driving force of biological processes is critically discussed. It is recalled that the concentration ratio of GSSG and GSH reflects little else than a steady state, which overwhelmingly results from fast enzymatic processes utilizing, degrading or regenerating GSH. A biological GSSG/GSH redox potential, as calculated by the Nernst equation, is a deduced electrochemical parameter based on direct measurements of GSH and GSSG that are often complicated by poorly substantiated assumptions. It is considered irrelevant to the steering of any biological process. GSH-utilizing enzymes depend on the concentration of GSH, not on [GSH](2), as is predicted by the Nernst equation, and are typically not affected by GSSG. Regulatory processes involving oxidants and GSH are considered to make use of mechanistic principles known for thiol peroxidases which catalyze the oxidation of hydroperoxides by GSH by means of an enzyme substitution mechanism involving only bimolecular reaction steps. The negligibly small rate constants of related spontaneous reactions as compared with enzyme-catalyzed ones underscore the superiority of kinetic parameters over electrochemical or thermodynamic ones for an in-depth understanding of GSH-dependent biological phenomena. At best, the GSSG/GSH potential might be useful as an analytical tool to disclose disturbances in redox metabolism. This article is part of a Special Issue entitled Cellular Functions of Glutathione. Copyright © 2012 Elsevier B.V. All rights reserved.

An unexplored role for Peroxiredoxin in exercise-induced redox signalling?

Directory of Open Access Journals (Sweden)

Alex J. Wadley

2016-08-01

Full Text Available Peroxiredoxin (PRDX is a ubiquitous oxidoreductase protein with a conserved ionised thiol that permits catalysis of hydrogen peroxide (H2O2 up to a million times faster than any thiol-containing signalling protein. The increased production of H2O2 within active tissues during exercise is thought to oxidise conserved cysteine thiols, which may in turn facilitate a wide variety of physiological adaptations. The precise mechanisms linking H2O2 with the oxidation of signalling thiol proteins (phosphates, kinases and transcription factors are unclear due to these proteins' low reactivity with H2O2 relative to abundant thiol peroxidases such as PRDX. Recent work has shown that following exposure to H2O2 in vitro, the sulfenic acid of the PRDX cysteine can form mixed disulphides with transcription factors associated with cell survival. This implicates PRDX as an ‘active’ redox relay in transmitting the oxidising equivalent of H2O2 to downstream proteins. Furthermore, under oxidative stress, PRDX can form stable oxidised dimers that can be secreted into the extracellular space, potentially acting as an extracellular ‘stress’ signal. There is extensive literature assessing non-specific markers of oxidative stress in response to exercise, however the PRDX catalytic cycle may offer a more robust approach for measuring changes in redox balance following exercise. This review discusses studies assessing PRDX-mediated cellular signalling and integrates the recent advances in redox biology with investigations that have examined the role of PRDX during exercise in humans and animals. Future studies should explore the role of PRDX as a key regulator of peroxide mediated-signal transduction during exercise in humans.

Fuzzy logic approach for energetic and economic evaluation of hydroelectric projects

International Nuclear Information System (INIS)

Iliev, Atanas M.

2003-01-01

A mathematical model for energetic and economic evaluation of hydroelectric projects is developed. The main advantage of the proposed methodology is that the model considers uncertainty and vagueness which appears during the decision making process. Due to modeling of variables that are non statistical in their character, fuzzy logic approach is fully incorporated in the model. The first step in energetic evaluation of the hydro power projects is determination of the characteristic of the efficiency of the units to be installed in hydro power plants. For this purpose the model which uses the best characteristics of Artificial Network Fuzzy Inference System (ANFIS) is applied. The method is tested on real systems: HPP Tikves- the power plant in operation and HPP Kozjak - the power plant in construction. The results obtained from practical implementation show that the proposed approach gives superior results than classical polynomial approximation. The model for determining the consumption characteristic of hydro power plant is developed by Sugeno Fuzzy Logic System with polynomials in the consequent part of the rules. Model takes into account the variable gross head of HPP, as well as, the number of units which will be in operation for given output. Modeling of the gross head and power output are performed by expert's design membership functions. This model is practically applied on HPP Tikves for determination of the consumption characteristic for several gross head. The plausible yearly production of electricity from hydro power project, which is important for estimation of the benefit from the project, is calculated by mixed fuzzy-statistical model. hi this approach fuzzy set of the inflow is constructed according to the statistical parameters. The calculation of the production of electricity is realized for a several hydrological conditions which are described by linguistic variables. Finally, Mamdani Fuzzy Inference System with fuzzy number in consequent part

Redox-Dependent Inflammation in Islet Transplantation Rejection

Directory of Open Access Journals (Sweden)

Jessie M. Barra

2018-04-01

Full Text Available Type 1 diabetes is an autoimmune disease that results in the progressive destruction of insulin-producing pancreatic β-cells inside the islets of Langerhans. The loss of this vital population leaves patients with a lifelong dependency on exogenous insulin and puts them at risk for life-threatening complications. One method being investigated to help restore insulin independence in these patients is islet cell transplantation. However, challenges associated with transplant rejection and islet viability have prevented long-term β-cell function. Redox signaling and the production of reactive oxygen species (ROS by recipient immune cells and transplanted islets themselves are key players in graft rejection. Therefore, dissipation of ROS generation is a viable intervention that can protect transplanted islets from immune-mediated destruction. Here, we will discuss the newly appreciated role of redox signaling and ROS synthesis during graft rejection as well as new strategies being tested for their efficacy in redox modulation during islet cell transplantation.

Redox-Dependent Inflammation in Islet Transplantation Rejection

Science.gov (United States)

Barra, Jessie M.; Tse, Hubert M.

2018-01-01

Type 1 diabetes is an autoimmune disease that results in the progressive destruction of insulin-producing pancreatic β-cells inside the islets of Langerhans. The loss of this vital population leaves patients with a lifelong dependency on exogenous insulin and puts them at risk for life-threatening complications. One method being investigated to help restore insulin independence in these patients is islet cell transplantation. However, challenges associated with transplant rejection and islet viability have prevented long-term β-cell function. Redox signaling and the production of reactive oxygen species (ROS) by recipient immune cells and transplanted islets themselves are key players in graft rejection. Therefore, dissipation of ROS generation is a viable intervention that can protect transplanted islets from immune-mediated destruction. Here, we will discuss the newly appreciated role of redox signaling and ROS synthesis during graft rejection as well as new strategies being tested for their efficacy in redox modulation during islet cell transplantation. PMID:29740396

The Causality between Government Expenditure and Economic Growth in Nigeria: A Toda-Yamamoto Approach

Directory of Open Access Journals (Sweden)

Michael Adebayo Ajayi

2016-01-01

Full Text Available The relationship between government expenditure and economic growth has been an issue of debate over the years. This study investigates the causality between government expenditure and economic growth in Nigeria between 1985 and 2014. Following the Toda-Yamamoto non-Granger causality testing approach, it finds that government expenditure and economic growth have no causal effect on each other. This offers evidence to invalidate Wagner’s law and the Keynesian proposition in Nigeria. This study recommends that government should strengthen its efforts to curtail corruption as well as introduce stricter checks and controls to reduce or eliminate the profligacy of public funds.

Redox active molecules cytochrome c and vitamin C enhance heme-enzyme peroxidations by serving as non-specific agents for redox relay

Energy Technology Data Exchange (ETDEWEB)

Gade, Sudeep Kumar; Bhattacharya, Subarna [Heme and Flavo Proteins Laboratory, 204, Center for Biomedical Research, VIT University, Vellore, Tamil Nadu 632014 (India); Manoj, Kelath Murali, E-mail: satyamjayatu@yahoo.com [Heme and Flavo Proteins Laboratory, 204, Center for Biomedical Research, VIT University, Vellore, Tamil Nadu 632014 (India)

2012-03-09

Highlights: Black-Right-Pointing-Pointer At low concentrations, cytochrome c/vitamin C do not catalyze peroxidations. Black-Right-Pointing-Pointer But low levels of cytochrome c/vitamin C enhance diverse heme peroxidase activities. Black-Right-Pointing-Pointer Enhancement positively correlates to the concentration of peroxide in reaction. Black-Right-Pointing-Pointer Reducible additives serve as non-specific agents for redox relay in the system. Black-Right-Pointing-Pointer Insight into electron transfer processes in routine and oxidative-stress states. -- Abstract: We report that incorporation of very low concentrations of redox protein cytochrome c and redox active small molecule vitamin C impacted the outcome of one-electron oxidations mediated by structurally distinct plant/fungal heme peroxidases. Evidence suggests that cytochrome c and vitamin C function as a redox relay for diffusible reduced oxygen species in the reaction system, without invoking specific or affinity-based molecular interactions for electron transfers. The findings provide novel perspectives to understanding - (1) the promiscuous role of cytochrome b{sub 5} in the metabolism mediated by liver microsomal xenobiotic metabolizing systems and (2) the roles of antioxidant molecules in affording relief from oxidative stress.

Non-economic determinants of economic development: methodology and influence

OpenAIRE

Barashov, N.

2011-01-01

The paper deals with research methodology of non-economic determinants of economic development. The author considers various theoretical approaches to definition of economic growth factors. Considerable attention is given to studying possible influence of non-economic determinants on quality of economic development.

A Benders decomposition approach for a combined heat and power economic dispatch

International Nuclear Information System (INIS)

Abdolmohammadi, Hamid Reza; Kazemi, Ahad

2013-01-01

Highlights: • Benders decomposition algorithm to solve combined heat and power economic dispatch. • Decomposing the CHPED problem into master problem and subproblem. • Considering non-convex heat-power feasible region efficiently. • Solving 4 units and 5 units system with 2 and 3 co-generation units, respectively. • Obtaining better or as well results in terms of objective values. - Abstract: Recently, cogeneration units have played an increasingly important role in the utility industry. Therefore the optimal utilization of multiple combined heat and power (CHP) systems is an important optimization task in power system operation. Unlike power economic dispatch, which has a single equality constraint, two equality constraints must be met in combined heat and power economic dispatch (CHPED) problem. Moreover, in the cogeneration units, the power capacity limits are functions of the unit heat productions and the heat capacity limits are functions of the unit power generations. Thus, CHPED is a complicated optimization problem. In this paper, an algorithm based on Benders decomposition (BD) is proposed to solve the economic dispatch (ED) problem for cogeneration systems. In the proposed method, combined heat and power economic dispatch problem is decomposed into a master problem and subproblem. The subproblem generates the Benders cuts and master problem uses them as a new inequality constraint which is added to the previous constraints. The iterative process will continue until upper and lower bounds of the objective function optimal values are close enough and a converged optimal solution is found. Benders decomposition based approach is able to provide a good framework to consider the non-convex feasible operation regions of cogeneration units efficiently. In this paper, a four-unit system with two cogeneration units and a five-unit system with three cogeneration units are analyzed to exhibit the effectiveness of the proposed approach. In all cases, the

Utilizing a vanadium redox flow battery to avoid wind power deviation penalties in an electricity market

International Nuclear Information System (INIS)

Turker, Burak; Arroyo Klein, Sebastian; Komsiyska, Lidiya; Trujillo, Juan José; Bremen, Lueder von; Kühn, Martin; Busse, Matthias

2013-01-01

Highlights: • Vanadium redox flow battery utilized for wind power grid integration was studied. • Technical and financial analyses at single wind farm level were performed. • 2 MW/6 MW h VRFB is suitable for mitigating power deviations for a 10 MW wind farm. • Economic incentives might be required in the short-term until the VRFB prices drop. - Abstract: Utilizing a vanadium redox flow battery (VRFB) for better market integration of wind power at a single wind farm level was evaluated. A model which combines a VRFB unit and a medium sized (10 MW) wind farm was developed and the battery was utilized to compensate for the deviations resulting from the forecast errors in an electricity market bidding structure. VRFB software model which was introduced in our previous paper was integrated with real wind power data, power forecasts and market data based on the Spanish electricity market. Economy of the system was evaluated by financial assessments which were done by considering the VRFB costs and the amount of deviation penalty payments resulting from forecast inaccuracies

"JCE" Classroom Activity #111: Redox Reactions in Three Representations

Science.gov (United States)

Nieves, Edgardo L. Ortiz; Barreto, Reizelie; Medina, Zuleika

2012-01-01

This activity introduces students to the concept of reduction-oxidation (redox) reactions. To help students obtain a thorough understanding of redox reactions, the concept is explored at three levels: macroscopic, submicroscopic, and symbolic. In this activity, students perform hands-on investigations of the three levels as they work at different…

Risk as economic category: systematics scientific approach and refinement contents

OpenAIRE

V.G. Vygovskyy

2015-01-01

The paper studies the categorical-conceptual apparatus of risk and its refinement based on a critical analysis of existing systematic scientific approaches. Determined that in the refinement of the economic nature of the risk of a number of controversial issues: the definition of the objective or subjective nature of risk; matching of concepts such as «risk», «danger», «loss», «probability of loss»; definition of negative or positive consequences of risk; identification of risk with its conse...

Carbon-free Solid Dispersion LiCoO2 Redox Couple Characterization and Electrochemical Evaluation for All Solid Dispersion Redox Flow Batteries

International Nuclear Information System (INIS)

Qi, Zhaoxiang; Liu, Aaron L.; Koenig, Gary M.

2017-01-01

Highlights: • LiCoO 2 particles can be cycled in carbon-free and binder-free coin cells. • A carbon-free LiCoO 2 suspension is electrochemically oxidized and reduced. • Comparable size LiCoO 2 and Li 4 Ti 5 O 12 suspensions have similar rheological properties. • First demonstration of redox couples with solid suspensions for both electrodes. - Abstract: Semi-solid flow batteries have been reported to have among the highest energy densities for redox flow batteries, however, they rely on percolated carbon networks which increase the electrolyte viscosity significantly. We report the first demonstration of carbon-free redox flow couples comprised of dispersed lithium-ion battery active material suspensions, with sub-micrometer LiCoO 2 (LCO) particles at the cathode and Li 4 Ti 5 O 12 (LTO) particles at the anode. Both electrochemical and rheological properties of the LCO suspensions are reported and compared to previous reports for LTO dispersed electrochemical redox couples. An LTO anode and LCO cathode full cell was constructed and reversible electrochemical redox reaction of the dispersed particles was successfully demonstrated. This carbon-free dispersed lithium-ion active material full cell provides a proof-of-concept for a system that lies between the relatively high viscosity semi-solid flow cells with percolated carbon networks and the relatively low energy density conventional flow cells comprised of dissolved transition metals, providing a system for future study of the trade-off between energy density and viscosity for electrochemical flow cells that rely on solid active materials.

Cascade redox flow battery systems

Science.gov (United States)

Horne, Craig R.; Kinoshita, Kim; Hickey, Darren B.; Sha, Jay E.; Bose, Deepak

2014-07-22

A reduction/oxidation ("redox") flow battery system includes a series of electrochemical cells arranged in a cascade, whereby liquid electrolyte reacts in a first electrochemical cell (or group of cells) before being directed into a second cell (or group of cells) where it reacts before being directed to subsequent cells. The cascade includes 2 to n stages, each stage having one or more electrochemical cells. During a charge reaction, electrolyte entering a first stage will have a lower state-of-charge than electrolyte entering the nth stage. In some embodiments, cell components and/or characteristics may be configured based on a state-of-charge of electrolytes expected at each cascade stage. Such engineered cascades provide redox flow battery systems with higher energy efficiency over a broader range of current density than prior art arrangements.

Electricity consumption and economic growth nexus in Portugal using cointegration and causality approaches

International Nuclear Information System (INIS)

Shahbaz, Muhammad; Tang, Chor Foon; Shahbaz Shabbir, Muhammad

2011-01-01

The aim of this paper is to re-examine the relationship between electricity consumption, economic growth, and employment in Portugal using the cointegration and Granger causality frameworks. This study covers the sample period from 1971 to 2009. We examine the presence of a long-run equilibrium relationship using the bounds testing approach to cointegration within the Unrestricted Error-Correction Model (UECM). Moreover, we examine the direction of causality between electricity consumption, economic growth, and employment in Portugal using the Granger causality test within the Vector Error-Correction Model (VECM). As a summary of the empirical findings, we find that electricity consumption, economic growth, and employment in Portugal are cointegrated and there is bi-directional Granger causality between the three variables in the long-run. With the exception of the Granger causality between electricity consumption and economic growth, the rest of the variables are also bi-directional Granger causality in the short-run. Furthermore, we find that there is unidirectional Granger causality running from economic growth to electricity consumption, but no evidence of reversal causality. - Highlights: → We re-examine the relationship between electricity consumption, economic growth, and employment in Portugal. → The electricity consumption and economic growth is causing each other in the long-run. → In the short-run, economic growth Granger-cause electricity consumption, but no evidence of reversal causality. → Energy conservation policy will deteriorate the process of economic growth in the long-run. → Portugal should increase investment on R and D to design new energy savings technology.

Reaction Mechanisms and Structural and Physicochemical Properties of Caffeic Acid Grafted Chitosan Synthesized in Ascorbic Acid and Hydroxyl Peroxide Redox System.

Science.gov (United States)

Liu, Jun; Pu, Huimin; Chen, Chong; Liu, Yunpeng; Bai, Ruyu; Kan, Juan; Jin, Changhai

2018-01-10

The ascorbic acid (AA) and hydroxyl peroxide (H 2 O 2 ) redox pair induced free radical grafting reaction is a promising approach to conjugate phenolic groups with chitosan (CS). In order to reveal the exact mechanisms of the AA/H 2 O 2 redox pair induced grafting reaction, free radicals generated in the AA/H 2 O 2 redox system were compared with hydroxyl radical ( • OH) produced in the Fe 2+ /H 2 O 2 redox system. Moreover, the structural and physicochemical properties of caffeic acid grafted CS (CA-g-CS) synthesized in these two redox systems were compared. Results showed that only ascorbate radical (Asc •- ) was produced in the AA/H 2 O 2 system. The reaction between Asc •- and CS produced novel carbon-centered radicals, whereas no new free radicals were detected when • OH reacted with CS. Thin layer chromatography, UV-vis, Fourier transform infrared, and nuclear magnetic resonance spectroscopic analyses all confirmed that CA was successfully grafted onto CS through Asc •- . However, CA could be hardly grafted onto CS via • OH. CA-g-CS synthesized through Asc •- exhibited lower thermal stability and crystallinity than the reaction product obtained through • OH. For the first time, our results demonstrated that the synthesis of CA-g-CS in the AA/H 2 O 2 redox system was mediated by Asc •- rather than • OH.