A new family of fluidic precursors for the self-templated synthesis of hierarchical nanoporous carbons

DOE PAGES

Fulvio, Pasquale F.; Hillesheim, Patrick C.; Oyola, Yatsandra; ...

2016-06-24

Hierarchical nanoporous nitrogen-doped carbons were prepared from task specific ionic liquids having a bis-imidazolium motif linked with various organic groups. While ethyl chains linking the imidazolium ions afford microporous-mesoporous carbons, long or aromatic groups resulted in microporous samples.

Anion-Functionalized Task-Specific Ionic Liquids: Molecular Origin of Change in Viscosity upon CO2 Capture.

PubMed

Li, Ailin; Tian, Ziqi; Yan, Tianying; Jiang, De-en; Dai, Sheng

2014-12-26

The structure and dynamics of a task-specific ionic liquid (TSIL), trihexyl(tetradecyl)phosphonium imidazolate, before and after absorbing CO(2) were studied with a molecular dynamics (MD) simulation. This particular ionic liquid is one of several newly discovered azole-based TSILs for equimolar CO(2) capture. Unlike other TSILs whose viscosity increases drastically upon reaction with CO(2), its viscosity decreases after CO(2) absorption. This unique behavior was confirmed in our MD simulation. We find that after CO(2) absorption the translational dynamics of the whole system is accelerated, accompanied by an accelerated rotational dynamics of the cations. Radial distribution function and spatial distribution function analyses show that the anions become asymmetric after reaction with CO(2), and this causes the imbalance of the interaction between the positive and negative regions of the ions. The interaction between the phosphorus atom of the cation and oxygen atoms of the carboxyl group on the anion is enhanced, while that between the phosphorus atom and the naked nitrogen atom of the anion is weakened. The ion-pair correlation functions further support that the weakened interaction leads to faster dissociation of cation-anion pairs, thereby causing an accelerated dynamics. Hence, the asymmetry of anions influences the dynamics of the system and affects the viscosity. This insight may help design better TSILs with decreased viscosity for CO(2) capture.

Ionic liquid assisted microwave synthesis route towards color-tunable luminescence of lanthanide- doped BiPO 4

DOE PAGES

Cybinska, Joanna; Lorbeer, Chantal; Mudring, Anja -Verena

2015-07-08

Ln 3+-doped (Ln=Sm, Eu, Tb, Dy) nanoparticles of BiPO 4 with a particle size below 10 nm were synthesized in a straightforward manner from the appropriate mixture of the respective metal acetates and the task-specific ionic liquids choline or butylammonium dihydrogen-phosphate by conversion in a laboratory microwave (120 °C, 10 min). The ionic liquid acts not only as a solvent and microwave susceptor, but also as the reaction partner and nanoparticle stabilizer. The materials were thoroughly characterized not only with respect to their optical properties but also by PXRD, FT-IR, TEM techniques. Furthermore, depending on the lanthanide, the nanomaterial showsmore » intense luminescence of different colors such as: orange (Sm 3+), red (Eu 3+), green (Tb 3+) or even white (Dy 3+).« less

Advances in QSPR/QSTR models of ionic liquids for the design of greener solvents of the future.

PubMed

Das, Rudra Narayan; Roy, Kunal

2013-02-01

In order to protect the life of all creatures living in the environment, the toxicity arising from various hazardous chemicals must be controlled. This imposes a serious responsibility on different chemical, pharmaceutical, and other biological industries to produce less harmful chemicals. Among various international initiatives on harmful aspects of chemicals, the 'Green Chemistry' ideology appears to be one of the most highlighted concepts that focus on the use of eco-friendly chemicals. Ionic liquids are a comparatively new addition to the huge garrison of chemical compounds released from the industry. Extensive research on ionic liquids in the past decade has shown them to be highly useful chemicals with a good degree of thermal and chemical stability, appreciable task specificity and minimal environmental release resulting in a notion of 'green chemical'. However, studies have also shown that ionic liquids are not intrinsically non-toxic agents and can pose severe degree of toxicity as well as the risk of bioaccumulation depending upon their structural components. Moreover, ionic liquids possess issues of waste generation during synthesis as well as separation problems. Predictive quantitative structure-activity relationship (QSAR) models constitute a rational opportunity to explore the structural attributes of ionic liquids towards various physicochemical and toxicological endpoints and thereby leading to the design of environmentally more benevolent analogues with higher process selectivity. Such studies on ionic liquids have been less extensive compared to other industrial chemicals. The present review attempts to summarize different QSAR studies performed on these chemicals and also highlights the safety, health and environmental issues along with the application specificity on the dogma of 'green chemistry'.

Iron species determination by task-specific ionic liquid-based in situ solvent formation dispersive liquid-liquid microextraction combined with flame atomic absorption spectrometry.

PubMed

Sadeghi, Susan; Ashoori, Vahid

2017-10-01

The task-specific ionic liquid (TSIL) of 1-ethyl-3-methylimidazolium bromide functionalized with 8-hydroxyquinoline was used as a chelating agent and extracting solvent for dispersive liquid-liquid microextraction and subsequent determination of Fe(III) by flame atomic absorption spectrometry. The in situ solvent formation of TSIL using KPF 6 provided the desired water-immiscible ionic liquid. The total Fe concentration could be determined after pre-oxidation of Fe(II) to Fe(III). Various factors affecting the proposed extraction procedure were optimized. The proposed analytical conditions were: sample pH 5, TSIL amount 0.3% (w/v), KPF 6 amount 0.15% (w/v), anti-sticking 0.1% (w/v) and salt concentration 5% (w/v). Under optimal conditions, the linear dynamic ranges for Fe(III) and total Fe were 20-80 and 20-110 ng mL -1 , respectively, with a detection limit of 6.9 ng mL -1 for Fe(III) and relative standard deviation of 2.2%. The proposed method was successfully applied to the determination of trace Fe(III) in water (underground, tap, refined water and artificial sea water) and beverage (apple, tomato, and tea) samples. The developed method offers advantages such as simplicity, ease of operation, and extraction of Fe(III) from aqueous solutions without the use of organic solvent. It was successfully applied for iron speciation in different real samples. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

A Phosphine-mediated Synthesis of 2,3,4,5-tetra-substituted N-hydroxypyrroles from α-oximino Ketones and Dialkyl Acetylenedicarboxylates Under Ionic Liquid Green-media.

PubMed

Shahvelayati, Ashraf S; Ghazvini, Maryam; Yadollahzadeh, Khadijeh; Delbari, Akram S

2018-01-01

The development of multicomponent reactions (MCRs) in the presence of task-specific ionic liquids (ILs), used not only as environmentally benign reaction media, but also as catalysts, is a new approach that meet with the requirements of sustainable chemistry. In recent years, the use of ionic liquids as a green media for organic synthesis has become a chief study area. This is due to their unique properties such as non-volatility, non-flammability, chemical and thermal stability, immiscibility with both organic compounds and water and recyclability. Ionic liquids are used as environmentally friendly solvents instead of hazardous organic solvents. We report the condensation reaction between α-oximinoketone and dialkyl acetylene dicarboxylate in the presence of triphenylphosphine to afford substituted pyrroles under ionic liquid conditions in good yields. Densely functionalized pyrroles was easily prepared from reaction of α-oximinoketones, dialkyl acetylene dicarboxylate in the presence of triphenylphosphine in a quantitative yield under ionic liquid conditions at room temperature. In conclusion, ionic liquids are indicated as a useful and novel reaction medium for the selective synthesis of functionalized pyrroles. This reaction medium can replace the use of hazardous organic solvents. Easy work-up, synthesis of polyfunctional compounds, decreased reaction time, having easily available-recyclable ionic liquids, and good to high yields are advantages of present method. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Choline-amino acid ionic liquids: past and recent achievements about the structure and properties of these really "green" chemicals.

PubMed

Gontrani, Lorenzo

2018-06-01

The structure of choline-amino acid ionic liquids, atoxic task-specific solvents composed of materials originated from renewable feedstocks, is reviewed in this letter. The varied and strong interactions that these liquids are capable of establishing are largely dependent on their structure and confer them outstanding solvating properties with respect to a large number of different solutes. Among the experimental methods capable of yielding structural insight, the energy-dispersive version of X-Ray diffraction, that uses the Bremsstrahlung radiation of the X-Ray tube, is a technique very well suited to investigate these liquid systems. The diffraction spectra of five choline-amino acid ionic liquids, recently measured, are reported and discussed; in particular, the presence or absence of the medium-range order pre-peak is related to the presence of polar groups within the amino acid side chain that destroys the hydrophobic interactions between aliphatic chains. In the final section, a recent example of choline-amino acid ionic liquids as for ancient paper preservation and two other interesting results are discussed at the end.

Ionic liquid syntheses via click chemistry: expeditious routes toward versatile functional materials.

PubMed

Mirjafari, Arsalan

2018-03-25

Since the introduction of click chemistry by K. B. Sharpless in 2001, its exploration and exploitation has occurred in countless fields of materials sciences in both academic and industrial spheres. Click chemistry is defined as an efficient, robust, and orthogonal synthetic platform for the facile formation of new carbon-heteroatom bonds, using readily available starting materials. Premier examples of click reactions are copper(i)-catalyzed azide-alkyne Huisgen cycloaddition (CuAAC) and the thiol-X (X = ene and yne) coupling reactions to form C-N and C-S bonds, respectively. The emphasis of this review is centered on the rapidly expanding area of click chemistry-mediated synthesis of functional ionic liquids via CuAAC, thiol-X and oxime formation, and selected examples of nucleophilic ring-opening reactions, while offering some thoughts on emerging challenges, opportunities and ultimately the evolution of this field. Click chemistry offers tremendous opportunities, and introduces intriguing perspectives for efficient and robust generation of tailored task-specific ionic liquids - an important class of soft materials.

A novel task specific magnetic polymeric ionic liquid for selective preconcentration of potassium in oil samples using centrifuge-less dispersive liquid-liquid microextraction technique and its determination by flame atomic emission spectroscopy.

PubMed

Beiraghi, Asadollah; Shokri, Masood

2018-02-01

In the present study a new centrifuge-less dispersive liquid-liquid microextraction technique based on application of a new task specific magnetic polymeric ionic liquid (TSMPIL) as a chelating and extraction solvent for selective preconcentration of trace amounts of potassium from oil samples is developed, for the first time. After extraction, the fine droplets of TSMPIL were transferred into an eppendorf tube and diluted to 500µL using distilled water. Then, the enriched analyte was determined by flame atomic emission spectroscopy (FAES). Several important factors affecting both the complexation and extraction efficiency including extraction time, rate of vortex agitator, amount of carbonyl iron powder, pH of sample solution, volume of ionic liquid as well as effects of interfering species were investigated and optimized. Under the optimal conditions, the limits of detection (LOD) and quantification (LOQ) were 0.5 and 1.6µgL -1 respectively with the preconcentration factor of 128. The precision (RSD %) for seven replicate determinations at 10µgL -1 of potassium was better than 3.9%. The relative recoveries for the spiked samples were in the acceptable range of 95-104%. The results demonstrated that no remarkable interferences are created by other various ions in the determination of potassium, so that the tolerance limits (W Ion /W K ) of major cations and anions were in the range of 2500-10,000. The purposed method was successfully applied for the analysis of potassium in some oil samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Ionic Self-Assembled Monolayer (ISAM) Nonlinear Optical Thin Films and Devices

DTIC Science & Technology

1998-05-12

SUBTITLE " Ionic Self-Assembled Monolayer (ISAM) Nonlinear Optical Thin Films and Devices" 6. AUTHORS Michael B. Miller 5. FUNDING NUMBERS F49620-97...ii. Lü. Ionic Self-Assembled Monolayer (ISAM) Nonlinear Optical Thin Films and Devices Final Technical Report Performance Period: 15 August 1997...Investigator F&S. Inc.N ̂ 1. INTRODUCTION .’ 2 2. PROGRAM TASK REVIEW 2 3. BACKGROUND 4 3.1 NONLINEAR OPTICAL THIN FILMS 4 3.2 IONIC SELF

Fluorescence recognition of chiral amino alcohols by using a novel ionic liquid sensor.

PubMed

Cai, Pengfei; Wu, Datong; Zhao, Xiaoyong; Pan, Yuanjiang

2017-08-07

A novel task-specific ionic liquid derived from l-phenylalaninol was prepared as an enantioselective fluorescent sensor for the first time. Fluorescent chiral ionic liquid 1 (FCIL1) is found to exhibit highly enantioselective fluorescence enhancements toward both aromatic and non-aromatic chiral amino alcohols. When (S)-FCIL1 was treated with the enantiomers of phenylalaninol, a great fluorescence enhancement at 349 nm could be observed and the value of the enantiomeric fluorescence difference (ef) is 5.92. This demonstrated that the chiral sensor (S)-FCIL1 exhibited an excellent enantioselective response behaviour to d-phenylalaninol. Besides that, both the fluorescence intensity at 349 nm (I 349 ) and the ratio of I 349 to I 282 depend linearly on the concentration of amino alcohols. Both the concentration and the enantiomeric composition could be determined by using the chiral ionic liquid. Differently, the sensor treated with the enantiomers of 2-amino-1-butanol showed an opposite result: the fluorescence intensity of the S-enantiomer is higher than that of the R-enantiomer. Furthermore, the size of the substituents on the chiral carbon might be important for the enantioselective fluorescent response.

Synthesis and characterization of low viscosity carbon dioxide binding organic liquids for flue gas clean up

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

Koech, Phillip K.; Malhotra, Deepika; Heldebrant, David J.

2015-01-01

Climate change is partly attributed to global anthropogenic carbon dioxide (CO2) emission to the atmosphere. These environmental effects can be mitigated by CO2 capture, utilization and storage. Alkanolamine solvents, such as monoethanolamine (MEA), which bind CO2 as carbamates or bicarbonate salts are used for CO2 capture in niche applications. These solvents consist of approximately 30 wt% of MEA in water, exhibiting a low, CO2-rich viscosity, fast kinetics and favorable thermodynamics. However, these solvents have low CO2 capacity and high heat capacity of water, resulting in prohibitively high costs of thermal solvent regeneration. Effective capture of the enormous amounts of CO2more » produced by coal-fired plants requires a material with high CO2 capacity and low regeneration energy requirements. To this end, several water-lean transformational solvents systems have been developed in order to reduce these energy penalties. These technologies include nano-material organic hybrids (NOHMs), task-specific, protic and conventional ionic liquids, phase change solvents. As part of an ongoing program in our group, we have developed new water lean transformational solvents known as CO2 binding organic liquids (CO2BOLs) which have the potential to be energy efficient CO2 capture solvents. These solvents, also known as switchable ionic liquids meaning, are organic solvents that can reversibly transform from non- ionic to ionic form and back. The zwitterionic state in these liquids is formed when low polarity non-ionic alkanolguanidines or alkanolamidines react with CO2 or SO2 to form ionic liquids with high polarity. These polar ionic liquids can be thermally converted to the less polar non-ionic solvent by releasing CO2.« less

Ionic Liquids as Unforeseen Assets to Fight Life-Threatening Mycotic Diseases.

PubMed

Hartmann, Diego O; Petkovic, Marija; Silva Pereira, Cristina

2016-01-01

Ionic liquids discovery has celebrated 100 years. They consist solely of ions, one of which is typically organic and asymmetrical. Remarkable physical and chemical properties stirred their use as alternative solvents in many chemical processes. The recent demonstration of their occurrence in nature might boost their interest in biological sciences. In the search of mechanistic understandings of ionic liquids' ecotoxicological impacts in fungi, we have analyzed the proteome, transcriptome, and metabolome responses to this chemical stress. Data illuminated new hypotheses that altered our research path - exploit ionic liquids as tools for the discovery of pathways and metabolites that may impact fungal development and pathogenicity. As we get closer to solve the primary effects of each ionic liquid family and their specific gene targets, the vision of developing antifungal ionic liquids and/or materials, by taking advantage of elegant progresses in this field, might become a reality. Task-designed formulations may improve the performance of conventional antifungal drugs, build functional coatings for reducing allergens production, or aid in the recovery of antifungal plant polymers. The frontier research in this cross-disciplinary field may provide us unforeseen means to address the global concern of mycotic diseases. Pathogenic and opportunistic fungi are responsible for numerous infections, killing annually nearly 1.5 million immunocompromised individuals worldwide, a similar rate to malaria or tuberculosis. This perspective will review our major findings and current hypotheses, contextualizing how they might bring us closer to efficient strategies to prevent and fight mycotic diseases.

Ultrasound promoted one pot synthesis of novel fluorescent triazolyl spirocyclic oxindoles using DBU based task specific ionic liquids and their antimicrobial activity.

PubMed

Singh, Harjinder; Sindhu, Jayant; Khurana, Jitender M; Sharma, Chetan; Aneja, K R

2014-04-22

Spirocyclic oxindoles and triazolyl derivatives posses remarkable biological activities. In present work, we have described an efficient one pot four-component domino reaction of 1-(prop-2-ynyl)indoline-2,3-dione, cyclic 1,3-diketones, malononitrile and various aryl azides in DBU based ionic liquids [DBU-H]OAc and [DBU-Bu]OH under ultrasonic irradiation for the construction of heterocycles, comprising spiro-oxindole, 2-amino-4H-pyran, and 1,2,3-triazoles substructures. The antimicrobial activity of all compounds has been investigated against six microbial strains. All compounds showed good antimicrobial activity. All newly synthesized compounds exhibit fluorescence in methanol with large stoke shift. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Design of LaPO4:Nd3+ materials by using ionic liquids

NASA Astrophysics Data System (ADS)

Cybinska, J.; Guzik, M.; Lorbeer, C.; Zych, E.; Guyot, Y.; Boulon, G.; Mudring, A.-V.

2017-01-01

Monoclinic monazite-type Nd3+-doped lanthanum orthophosphate (LaPO4:Nd3+) nanoparticles were prepared by microwave treatment of simple lanthanide precursors such as Nd(OAc)3•xH2O, OAc = acetate) with task-specific dihydrogen phosphate ionic liquids (ILs) 1-butyl-1-methylpyrrolidinium dihydrogenphosphate- BmPyrH2PO4 (IL1) and 2-hydroxyethyl-N,N,N-trimethylammonium, [choline][H2PO4] (IL2) as the reaction medium, reactant and in-situ nanoparticle stabilizer. This synthesis route possesses many advantages as it is a fast and facile preparation method of the desired phosphate nanomaterials without the necessity for post-reaction heat treatment to obtain the anhydrous high temperature monazite phosphate phase. The nano-sized phosphors Nd3+:LaPO4 were carefully analyzed by the powder X-ray diffraction, electron microscopy and spectroscopic techniques taking advantage of the Nd3+ spectroscopic probe to analyze in detail the structural properties. Applied high resolution low temperature absorption and emission techniques allowed to complete the structural information unavailable from the XRD powder patterns. A clear influence of the used task-specific dihydrogen phosphate ILs on the structure, morphology, luminescence intensity and lifetimes of the obtained Nd3+:LaPO4 was found. It is worth noting that the Nd3+ luminescence in LaPO4 has never been reported up to now.

The ionic DTI model (iDTI) of dynamic diffusion tensor imaging (dDTI)

PubMed Central

Makris, Nikos; Gasic, Gregory P.; Garrido, Leoncio

2014-01-01

Measurements of water molecule diffusion along fiber tracts in CNS by diffusion tensor imaging (DTI) provides a static map of neural connections between brain centers, but does not capture the electrical activity along axons for these fiber tracts. Here, a modification of the DTI method is presented to enable the mapping of active fibers. It is termed dynamic diffusion tensor imaging (dDTI) and is based on a hypothesized “anisotropy reduction due to axonal excitation” (“AREX”). The potential changes in water mobility accompanying the movement of ions during the propagation of action potentials along axonal tracts are taken into account. Specifically, the proposed model, termed “ionic DTI model”, was formulated as follows.•First, based on theoretical calculations, we calculated the molecular water flow accompanying the ionic flow perpendicular to the principal axis of fiber tracts produced by electrical conduction along excited myelinated and non-myelinated axons.•Based on the changes in molecular water flow we estimated the signal changes as well as the changes in fractional anisotropy of axonal tracts while performing a functional task.•The variation of fractional anisotropy in axonal tracts could allow mapping the active fiber tracts during a functional task. Although technological advances are necessary to enable the robust and routine measurement of this electrical activity-dependent movement of water molecules perpendicular to axons, the proposed model of dDTI defines the vectorial parameters that will need to be measured to bring this much needed technique to fruition. PMID:25431757

Understanding SO2 Capture by Ionic Liquids.

PubMed

Mondal, Anirban; Balasubramanian, Sundaram

2016-05-19

Ionic liquids have generated interest for efficient SO2 absorption due to their low vapor pressure and versatility. In this work, a systematic investigation of the structure, thermodynamics, and dynamics of SO2 absorption by ionic liquids has been carried out through quantum chemical calculations and molecular dynamics (MD) simulations. MP2 level calculations of several ion pairs complexed with SO2 reveal its preferential interaction with the anion. Results of condensed phase MD simulations of SO2-IL mixtures manifested the essential role of both cations and anions in the solvation of SO2, where the solute is surrounded by the "cage" formed by the cations (primarily its alkyl tail) through dispersion interactions. These structural effects of gas absorption are substantiated by calculated Gibbs free energy of solvation; the dissolution is demonstrated to be enthalpy driven. The entropic loss of SO2 absorption in ionic liquids with a larger anion such as [NTf2](-) has been quantified and has been attributed to the conformational restriction of the anion imposed by its interaction with SO2. SO2 loading IL decreases its shear viscosity and enhances the electrical conductivity. This systematic study provides a molecular level understanding which can aid the design of task-specific ILs as electrolytes for efficient SO2 absorption.

In-situ functionalization of mesoporous hexagonal ZnO synthesized in task specific ionic liquid as a photocatalyst for elimination of SO2, NOx, and CO

NASA Astrophysics Data System (ADS)

Kowsari, Elaheh; Abdpour, Soheil

2017-12-01

A novel mesoporous structure of zinc oxide was synthesized in hydrothermal autocalve in the presence of a functional ionic liquid (FIL) {[CH2CH2] O2 (mm)2}. This FIL with ether groups was used simultaneously as a designer templating agent and a source of the hydroxyl radical. The presence of this ionic liquid led to producing ethylene glycol in the reaction media, which adsorb on the surface of mesoporous hexagonal ZnO plates. These mesoporous structures can adsorb pollutant gases and increase photocatalytic oxidation of pollutant gases in compare with commercial ZnO nanoparticles and agglomerated nanoparticles synthesized in this work. XPS data confirmed ethylene glycol production by the ionic liquid, which could prove a role for ionic liquids as designers. The estimated BET surface area values of ZnO hexagonal mesoporous plates and agglomerated particles were 84 m2/g and 12 m2/g respectively. Optical properties of the mesoporous structures were analyzed by photoluminescence spectroscopy and diffuse reflectance UV-visible spectroscopy. The performance of these structures as efficient photocatalysts was further demonstrated by their removal of NOx, SO2, and CO under UV irradiation. The removal of NOx, SO2, and CO under UV irradiation was 56%, 81%, and 35% respectively, after 40 min of irradiation time. Reusability of the photocatalyst was determined; the results show no significant decrease of activity of photocatalyst. after five cycles.

Hydrophobic task-specific ionic liquids: synthesis, properties and application for the capture of SO2.

PubMed

Tian, Shidong; Hou, Yucui; Wu, Weize; Ren, Shuhang; Qian, Jianguo

2014-08-15

The capture of SO2 by ionic liquids (ILs) has drawn much attention all over the world. However, ILs can absorb not only SO2 but also water from flue gas. The removal of water from ILs is necessary for reusing the absorbent. In order to reduce the energy costs of removing water, it would be helpful to weaken the interactions between ILs and water. In this work, two kinds of hydrophobic task-specific ILs, 1-(2-diethyl-aminoethyl)-3-methylimidazolium hexafluorophosphate ([Et2NEmim] [PF6]) and 1-(2-diethyl-aminoethyl)-1-methylpyrrolidinium hexafluorophosphate ([Et2NEmpyr][PF6]), were designed and synthesized. Thermal stability and physical properties of the ILs were studied. Furthermore, the application of the ILs for the capture of SO2 and the absorption mechanism were systematically investigated. It has been found that both of the ILs are immiscible with water, and [Et2NEmim][PF6] has much lower viscosity, much higher thermal stability and much higher SO2 absorption rate than [Et2NEmpyr][PF6]. [Et2NEmim][PF6] shows high SO2 absorption capacities up to 2.11 mol SO2 per mole IL (pure SO2) and 0.94 mol SO2 per mole IL (3% SO2) under hydrous conditions at 30 °C. The result suggests that [Et2NEmim][PF6] is a promising recyclable absorbent for the capture of SO2. Copyright © 2014 Elsevier B.V. All rights reserved.

Ionic Liquids as Electrolytes for Electrochemical Double-Layer Capacitors: Structures that Optimize Specific Energy.

PubMed

Mousavi, Maral P S; Wilson, Benjamin E; Kashefolgheta, Sadra; Anderson, Evan L; He, Siyao; Bühlmann, Philippe; Stein, Andreas

2016-02-10

Key parameters that influence the specific energy of electrochemical double-layer capacitors (EDLCs) are the double-layer capacitance and the operating potential of the cell. The operating potential of the cell is generally limited by the electrochemical window of the electrolyte solution, that is, the range of applied voltages within which the electrolyte or solvent is not reduced or oxidized. Ionic liquids are of interest as electrolytes for EDLCs because they offer relatively wide potential windows. Here, we provide a systematic study of the influence of the physical properties of ionic liquid electrolytes on the electrochemical stability and electrochemical performance (double-layer capacitance, specific energy) of EDLCs that employ a mesoporous carbon model electrode with uniform, highly interconnected mesopores (3DOm carbon). Several ionic liquids with structurally diverse anions (tetrafluoroborate, trifluoromethanesulfonate, trifluoromethanesulfonimide) and cations (imidazolium, ammonium, pyridinium, piperidinium, and pyrrolidinium) were investigated. We show that the cation size has a significant effect on the electrolyte viscosity and conductivity, as well as the capacitance of EDLCs. Imidazolium- and pyridinium-based ionic liquids provide the highest cell capacitance, and ammonium-based ionic liquids offer potential windows much larger than imidazolium and pyridinium ionic liquids. Increasing the chain length of the alkyl substituents in 1-alkyl-3-methylimidazolium trifluoromethanesulfonimide does not widen the potential window of the ionic liquid. We identified the ionic liquids that maximize the specific energies of EDLCs through the combined effects of their potential windows and the double-layer capacitance. The highest specific energies are obtained with ionic liquid electrolytes that possess moderate electrochemical stability, small ionic volumes, low viscosity, and hence high conductivity, the best performing ionic liquid tested being 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide.

Hollow fiber-supported designer ionic liquid sponges for post-combustion CO2 scrubbing

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

Lee, JS; Hillesheim, PC; Huang, DK

A proof of concept study for a new type of carbon capture system is considered for post-combustion CO2 capture based on porous hollow fiber sorbents with ionic liquids sorbed in the cell walls of the fiber. This study proves that delicate morphological features in the open-celled porous wall can be maintained during the infusion process. Mixtures of task specific ionic liquid (i.e. [BMIM][Tf2N]) and superbase (i.e. DBU) were loaded into polyamide-imide (PAI) fibers by a so-called two-step non-solvent infusion protocol. In the protocol, methanol carries ionic liquids into the pore cell walls of hollow fibers and then hexane carries superbasemore » to create an efficient CO2 sorbent. Our ionic liquid/superbase impregnation technique overcomes a serious increase in mass transfer resistance upon reaction with CO2, thereby allowing its large scale utilization for post-combustion CO2 capture. The investigation on the effect of different pore former additives (different molecular weights of polyvinylpyrrolidone, lithium nitrate, and their mixtures) suggested that a large molecular weight of PVP (M-w; 1300k) including dope composition produces highly interconnected open cell pore structures of PAI hollow fibers. Lastly, a lumen side barrier layer was successfully formed on the bore side of neat PAI fibers by using a mixture of Neoprene (R) with crosslinking agents (TSR-633) via a post-treatment process. The lumen layer will enable heat removal from the fiber sorbents during their application in rapid thermal swing cycling processes. (C) 2012 Elsevier Ltd. All rights reserved.« less

Viscosity, conductivity, and electrochemical property of dicyanamide ionic liquids

NASA Astrophysics Data System (ADS)

Yuan, Wen-Li; Yang, Xiao; He, Ling; Xue, Ying; Qin, Song; Tao, Guo-Hong

2018-03-01

The instructive structure-property relationships of ionic liquids (ILs) can be put to task-specific design of new functionalized ILs. The dicyanamide (DCA) ILs are typical CHN type ILs which are halogen free, chemical stable, low-viscous and fuel-rich. The transport properties of DCA ionic liquids are significant for their applications as solvents, electrolytes and hypergolic propellants. This work systematically investigates several important transport properties of four DCA ILs ([C4mim][N(CN)2], [C4m2im][N(CN)2], N4442[N(CN)2], and N8444[N(CN)2]) including viscosity, conductivity, and electrochemical property at different temperatures. The melting points, temperature-dependent viscosities and conductivities reveal the structure-activity relationship of four DCA ILs. From the Walden plots, the imidazolium cations exhibit stronger cation–anion attraction than the ammonium cations. DCA ILs have relatively high values of electrochemical windows (EWs), which indicates that the DCA ILs are potential candidates for electrolytes in electrochemical applications. The cyclic voltammograms of Eu(III) in these DCA ILs at GC working electrode at various temperatures 303–333 K consists of quasi-reversible waves. The electrochemical properties of the DCA ILs are also dominated by the cationic structures. The current intensity (ip), the diffusion coefficients (Do), the charge transfer rate constants (ks) of Eu(III) in DCA ILs all increased with the molar conductivities increased. The cationic structure-transport property relationships of DCA ILs were constructed for designing novel functionalized ILs to fulfill specific demands.

Viscosity, Conductivity, and Electrochemical Property of Dicyanamide Ionic Liquids

PubMed Central

Yuan, Wen-Li; Yang, Xiao; He, Ling; Xue, Ying; Qin, Song; Tao, Guo-Hong

2018-01-01

The instructive structure-property relationships of ionic liquids (ILs) can be put to task-specific design of new functionalized ILs. The dicyanamide (DCA) ILs are typical CHN type ILs which are halogen free, chemical stable, low-viscous, and fuel-rich. The transport properties of DCA ionic liquids are significant for their applications as solvents, electrolytes, and hypergolic propellants. This work systematically investigates several important transport properties of four DCA ILs ([C4mim][N(CN)2], [C4m2im][N(CN)2], N4442[N(CN)2], and N8444[N(CN)2]) including viscosity, conductivity, and electrochemical property at different temperatures. The melting points, temperature-dependent viscosities and conductivities reveal the structure-activity relationship of four DCA ILs. From the Walden plots, the imidazolium cations exhibit stronger cation–anion attraction than the ammonium cations. DCA ILs have relatively high values of electrochemical windows (EWs), which indicates that the DCA ILs are potential candidates for electrolytes in electrochemical applications. The cyclic voltammograms of Eu(III) in these DCA ILs at GC working electrode at various temperatures 303–333 K consists of quasi-reversible waves. The electrochemical properties of the DCA ILs are also dominated by the cationic structures. The current intensity (ip), the diffusion coefficients (Do), the charge transfer rate constants (ks) of Eu(III) in DCA ILs all increased with the molar conductivities increased. The cationic structure-transport property relationships of DCA ILs were constructed for designing novel functionalized ILs to fulfill specific demands. PMID:29600245

Cellulosic-Derived Biofuels Program in Kentucky - Part 2

DTIC Science & Technology

2014-04-30

and lignin, are complex raw materials. Selection of robust strains of algae that are able to convert C6 (glucose) and C5 carbohydrates from...13 Task B2.03 Development of Metalloporphyrin-Ionic Liquid Complexes for Degradation of Biomass . 14 Task B2.04 –Biomass Conversion Process Scale...Up ............................................................................. 15 Task B3: Carbohydrate to Oil Conversion Process Development

Ionic liquid containing hydroxamate and N-alkyl sulfamate ions

DOEpatents

Friesen, Cody A.; Wolfe, Derek; Johnson, Paul Bryan

2016-03-15

Embodiments of the invention are related to ionic liquids and more specifically to ionic liquids used in electrochemical metal-air cells in which the ionic liquid includes a cation and an anion selected from hydroxamate and/or N-alkyl sulfamate anions.

Comparison of Three Ionic Liquid-Tolerant Cellulases by Molecular Dynamics

PubMed Central

Jaeger, Vance; Burney, Patrick; Pfaendtner, Jim

2015-01-01

We have employed molecular dynamics to investigate the differences in ionic liquid tolerance among three distinct family 5 cellulases from Trichoderma viride, Thermogata maritima, and Pyrococcus horikoshii. Simulations of the three cellulases were conducted at a range of temperatures in various binary mixtures of the ionic liquid 1-ethyl-3-methyl-imidazolium acetate with water. Our analysis demonstrates that the effects of ionic liquids on the enzymes vary in each individual case from local structural disturbances to loss of much of one of the enzyme’s secondary structure. Enzymes with more negatively charged surfaces tend to resist destabilization by ionic liquids. Specific and unique structural changes in the enzymes are induced by the presence of ionic liquids. Disruption of the secondary structure, changes in dynamical motion, and local changes in the binding pocket are observed in less tolerant enzymes. Ionic-liquid-induced denaturation of one of the enzymes is indicated over the 500 ns timescale. In contrast, the most tolerant cellulase behaves similarly in water and in ionic-liquid-containing mixtures. Unlike the heuristic approaches that attempt to predict enzyme stability using macroscopic properties, molecular dynamics allows us to predict specific atomic-level structural and dynamical changes in an enzyme’s behavior induced by ionic liquids and other mixed solvents. Using these insights, we propose specific experimentally testable hypotheses regarding the origin of activity loss for each of the systems investigated in this study. PMID:25692593

On the relationship between the specific heat enhancement of salt-based nanofluids and the ionic exchange capacity of nanoparticles.

PubMed

Mondragón, Rosa; Juliá, J Enrique; Cabedo, Luis; Navarrete, Nuria

2018-05-14

Nanoparticles have been used in thermal applications to increase the specific heat of the molten salts used in Concentrated Solar Power plants for thermal energy storage. Although several mechanisms for abnormal enhancement have been proposed, they are still being investigated and more research is necessary. However, this nanoparticle-salt interaction can also be found in chemical applications in which nanoparticles have proved suitable to be used as an adsorbent for nitrate removal given their high specific surface, reactivity and ionic exchange capacity. In this work, the ionic exchange capacity mechanism for the nanoparticles functionalization phenomenon was evaluated. The ionic exchange capacity of silica and alumina nanoparticles dispersed in lithium, sodium and potassium nitrates was measured. Fourier-transform infrared spectroscopy tests confirmed the adsorption of nitrate ions on the nanoparticle surface. A relationship between the ionic exchange capacity of nanoparticles and the specific heat enhancement of doped molten salts was proposed for the first time.

Engineering the electrochemical capacitive properties of graphene sheets in ionic-liquid electrolytes by correct selection of anions.

PubMed

Shi, Minjie; Kou, Shengzhong; Yan, Xingbin

2014-11-01

Graphene sheet (GS)-ionic liquid (IL) supercapacitors are receiving intense interest because their specific energy density far exceeds that of GS-aqueous electrolytes supercapacitors. The electrochemical properties of ILs mainly depend on their diverse ions, especially anions. Therefore, identifying suitable IL electrolytes for GSs is currently one of the most important tasks. The electrochemical behavior of GSs in a series of ILs composed of 1-ethyl-3-methylimidazolium cation (EMIM(+)) with different anions is systematically studied. Combined with the formula derivation and building models, it is shown that the viscosity, ion size, and molecular weight of ILs affect the electrical conductivity of ILs, and thus, determine the electrochemical performances of GSs. Because the EMIM-dicyanamide IL has the lowest viscosity, ion size, and molecular weight, GSs in it exhibit the highest specific capacitance, smallest resistance, and best rate capability. In addition, because the tetrafluoroborate anion (BF4(-)) has the best electrochemical stability, the GS-[EMIM][BF4] supercapacitor has the widest potential window, and thus, displays the largest energy density. These results may provide valuable information for selecting appropriate ILs and designing high-performance GS-IL supercapacitors to meet different needs. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Technologies for Developing Predictive Atomistic and Coarse-Grained Force Fields for Ionic Liquid Property Prediction

DTIC Science & Technology

2008-07-29

studied are set to zero and a constrained MM minimization is performed. It is critical that all other force field parameters (for bonds, angles, charges...identifying the symmetry of the problem and tailoring the parameterization accordingly may be critical . For Phase I, the above described procedure was...tasks and the evaluation of their properties. The tremendous number of possible ionic liquids that are within reach makes it critical that a reliable

Ionic liquid/water mixtures: from hostility to conciliation.

PubMed

Kohno, Yuki; Ohno, Hiroyuki

2012-07-21

Water was originally inimical to ionic liquids (ILs) especially in the analysis of their detailed properties. Various data on the properties of ILs indicate that there are two ways to design functions of ionic liquids. The first is to change the structure of component ions, to provide "task-specific ILs". The second is to mix ILs with other components, such as other ILs, organic solvents or water. Mixing makes it easy to control the properties of the solution. In this strategy, water is now a very important partner. Below, we summarise our recent results on the properties of IL/water mixtures. Stable phase separation is an effective method in some separation processes. Conversely, a dynamic phase change between a homogeneous mixture and separation of phases is important in many fields. Analysis of the relation between phase behaviour and the hydration state of the component ions indicates that the pattern of phase separation is governed by the hydrophilicity of the ions. Sufficiently hydrophilic ions yielded ILs that are miscible with water, and hydrophobic ions gave stable phase separation with water. ILs composed of hydrophobic but hydrated ions undergo a dynamic phase change between a homogeneous mixture and separate phases according to temperature. ILs having more than seven water molecules per ion pair undergo this phase transition. These dynamic phase changes are considered, with some examples, and application is made to the separation of water-soluble proteins.

Divergent trend in density versus viscosity of ionic liquid/water mixtures: a molecular view from guanidinium ionic liquids.

PubMed

Singh, Akhil Pratap; Gardas, Ramesh L; Senapati, Sanjib

2015-10-14

Ionic liquids (ILs) have shown great potential in the dissolution and stability of biomolecules when a low-to-moderate quantity of water is added. Hence, determining the thermophysical properties and understanding these novel mixtures at the molecular level are of both fundamental and practical importance. In this context, here we report the synthesis of two nontoxic guanidinium cation based ILs, tetramethylguanidinium benzoate [TMG][BEN] and tetramethylguanidinium salicylate [TMG][SAL], and present a detailed comparison of their thermophysical properties in the presence of water. The results show that the [TMG][SAL]/water mixtures have higher density and higher apparent molar volume, but a lower viscosity and higher compressibility than the [TNG][BEN]/water mixtures. The measured viscosity and compressibility data are explained from ab initio quantum mechanical calculations and liquid-phase molecular dynamics simulations, where salicylate anions of denser [TMG][SAL]/water were found to exist as isolated ions due to intramolecular H-bonding. On the contrary, intermolecular H-bonding among the benzoate anions and their strong tendency to form an extended H-bonding network with water made [TMG][BEN]/water solutions more viscous and less compressible. This study shows the importance of probing these emerging solvents at the molecular-to-atomic level, which could be helpful in their optimal usage for task-specific applications.

Hydrogen-bonding interactions between a nitrile-based functional ionic liquid and DMSO

NASA Astrophysics Data System (ADS)

Zheng, Yan-Zhen; Zhou, Yu; Deng, Geng; Yu, Zhi-Wu

2016-11-01

Task-specific ionic liquids (TSILs) have been introduced by incorporating additional functional groups in the cation or anion to impart specific properties or reactivates. In this work, the hydrogen-bonding interactions between a nitrile-functional TSIL 1-propylnitrile-3-methylimidazolium tetrafluoroborate ([PCNMIM][BF4]) and dimethyl sulphoxide (DMSO) were investigated in detail by attenuated total reflection infrared spectroscopy (ATR-IR), combined with hydrogen nuclear magnetic resonance (1H NMR) and density functional theory calculations (DFT). It was found that, first, introducing a nitrile group into the alkyl chain does not change the main interaction site in the cation. It is still the C2 hydrogen. So the v(C2-H) is more sensitive to the environmental change and can be used as an indicator of the environments change of IL. Second, the wavenumber shift changes of v(C2-H) have two turning points (xDMSO ≈ 0.6 and 0.9), dividing the dilution process into three stages. Combined with the calculation results, the dilution process is identified as: From larger ion clusters to smaller ion clusters (xDMSO < 0.6), then to ion pairs (0.6 0.9). Introducing a nitrile group into the alkyl chain does not influence the dilution process of IL dissolving in DMSO. Third, the Ctbnd N in [PCNMIM][BF4] can work as an electron donor in forming hydrogen-bonds with the methyl group of [PCNMIM]+ and DMSO, but its strength is weaker than that formed by the imidazolium ring C-Hs. The dual roles of the cation to work as both electron acceptor and donor expand the wide applications of this nitrile-functional ionic liquid.

Ionic Liquid-Liquid Chromatography: A New General Purpose Separation Methodology.

PubMed

Brown, Leslie; Earle, Martyn J; Gîlea, Manuela A; Plechkova, Natalia V; Seddon, Kenneth R

2017-08-10

Ionic liquids can form biphasic solvent systems with many organic solvents and water, and these solvent systems can be used in liquid-liquid separations and countercurrent chromatography. The wide range of ionic liquids that can by synthesised, with specifically tailored properties, represents a new philosophy for the separation of organic, inorganic and bio-based materials. A customised countercurrent chromatograph has been designed and constructed specifically to allow the more viscous character of ionic liquid-based solvent systems to be used in a wide variety of separations (including transition metal salts, arenes, alkenes, alkanes, bio-oils and sugars).

Confused ionic liquid ions--a "liquification" and dosage strategy for pharmaceutically active salts.

PubMed

Bica, Katharina; Rogers, Robin D

2010-02-28

We present a strategy to expand the liquid and compositional ranges of ionic liquids, specifically pharmaceutically active ionic liquids, by simple mixing with a solid acid or base to form oligomeric ions.

Electrochemically stable electrolytes

DOEpatents

Angell, Charles Austen; Zhang, Sheng-Shui; Xu, Kang

1999-01-01

This invention relates generally to inorganic ionic liquids which function as electrolytes and do not crystallize at ambient temperature. More specifically, this invention is directed to quasi-salt inorganic ionic liquids which comprise the reaction product of a strong Lewis acid with an inorganic halide-donating molecule. This invention is further directed to quasi-salt inorganic ionic liquid mixtures which comprise combinations of electrolyte additives and quasi-salt inorganic ionic liquids. These quasi-salt inorganic ionic liquid mixtures are useful electrolytes.

Electrochemically stable electrolytes

DOEpatents

Angell, C.A.; Zhang, S.S.; Xu, K.

1999-01-05

This invention relates generally to inorganic ionic liquids which function as electrolytes and do not crystallize at ambient temperature. More specifically, this invention is directed to quasi-salt inorganic ionic liquids which comprise the reaction product of a strong Lewis acid with an inorganic halide-donating molecule. This invention is further directed to quasi-salt inorganic ionic liquid mixtures which comprise combinations of electrolyte additives and quasi-salt inorganic ionic liquids. These quasi-salt inorganic ionic liquid mixtures are useful electrolytes. 16 figs.

Intelligent control of an IPMC actuated manipulator using emotional learning-based controller

NASA Astrophysics Data System (ADS)

Shariati, Azadeh; Meghdari, Ali; Shariati, Parham

2008-08-01

In this research an intelligent emotional learning controller, Takagi- Sugeno- Kang (TSK) is applied to govern the dynamics of a novel Ionic-Polymer Metal Composite (IPMC) actuated manipulator. Ionic-Polymer Metal Composites are active actuators that show very large deformation in existence of low applied voltage. In this research, a new IPMC actuator is considered and applied to a 2-dof miniature manipulator. This manipulator is designed for miniature tasks. The control system consists of a set of neurofuzzy controller whose parameters are adapted according to the emotional learning rules, and a critic with task to assess the present situation resulted from the applied control action in terms of satisfactory achievement of the control goals and provides the emotional signal (the stress). The controller modifies its characteristics so that the critic's stress decreased.

Biokinetic data and models for occupational intake of lanthanoids

DOE PAGES

Leggett, Richard Wayne; Ansoborlo, Eric; Bailey, Michael; ...

2014-05-12

The lanthanoid (or lanthanide) chemical elements comprise fifteen elements with atomic numbers 57 (lanthanum) through 71 (lutetium). This paper reviews data related to the biological behavior of these elements in the human body and proposes biokinetic models for application to occupational intake of radio-lanthanoids. Generic (element-independent) absorption rates from the respiratory and alimentary tracts to blood are proposed. The proposed systemic models are largely generic but include some element-specific parameter values to reflect regular changes with ionic radius in certain aspects of the behavior of the lanthanoids. This work was performed within the internal dosimetry task group (INDOS) of Committeemore » 2 of the International Commission on Radiological Protection (ICRP).« less

Ionic liquids: Promising green solvents for lignocellulosic biomass utilization

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

Yoo, Chang Geun; Pu, Yunqiao; Ragauskas, Arthur J.

Ionic liquids are effective solvents/media for the utilization of lignocellulosic biomass. The unique properties of ionic liquids enable them to effectively dissolve and/or convert the biomass into various types of products. This review aims to cover the latest progress achieved in applications of ionic liquids on biomass conversion and analysis. Specifically, several recently developed approaches on how to overcome current challenges on the use of ionic liquids in the biomass conversion were highlighted. Here, recent studies addressing the potential applications of ionic liquids for the production of novel biomass-derived chemicals and materials were also discussed.

Ionic liquids: Promising green solvents for lignocellulosic biomass utilization

DOE PAGES

Yoo, Chang Geun; Pu, Yunqiao; Ragauskas, Arthur J.

2017-06-01

Ionic liquids are effective solvents/media for the utilization of lignocellulosic biomass. The unique properties of ionic liquids enable them to effectively dissolve and/or convert the biomass into various types of products. This review aims to cover the latest progress achieved in applications of ionic liquids on biomass conversion and analysis. Specifically, several recently developed approaches on how to overcome current challenges on the use of ionic liquids in the biomass conversion were highlighted. Here, recent studies addressing the potential applications of ionic liquids for the production of novel biomass-derived chemicals and materials were also discussed.

Microscopic properties of ionic liquid/organic semiconductor interfaces revealed by molecular dynamics simulations.

PubMed

Yokota, Yasuyuki; Miyamoto, Hiroo; Imanishi, Akihito; Takeya, Jun; Inagaki, Kouji; Morikawa, Yoshitada; Fukui, Ken-Ichi

2018-05-09

Electric double-layer transistors based on ionic liquid/organic semiconductor interfaces have been extensively studied during the past decade because of their high carrier densities at low operation voltages. Microscopic structures and the dynamics of ionic liquids likely determine the device performance; however, knowledge of these is limited by a lack of appropriate experimental tools. In this study, we investigated ionic liquid/organic semiconductor interfaces using molecular dynamics to reveal the microscopic properties of ionic liquids. The organic semiconductors include pentacene, rubrene, fullerene, and 7,7,8,8-tetracyanoquinodimethane (TCNQ). While ionic liquids close to the substrate always form the specific layered structures, the surface properties of organic semiconductors drastically alter the ionic dynamics. Ionic liquids at the fullerene interface behave as a two-dimensional ionic crystal because of the energy gain derived from the favorable electrostatic interaction on the corrugated periodic substrate.

Ionic liquids in chemical engineering.

PubMed

Werner, Sebastian; Haumann, Marco; Wasserscheid, Peter

2010-01-01

The development of engineering applications with ionic liquids stretches back to the mid-1990s when the first examples of continuous catalytic processes using ionic liquids and the first studies of ionic liquid-based extractions were published. Ever since, the use of ionic liquids has seen tremendous progress in many fields of chemistry and engineering, and the first commercial applications have been reported. The main driver for ionic liquid engineering applications is to make practical use of their unique property profiles, which are the result of a complex interplay of coulombic, hydrogen bonding and van der Waals interactions. Remarkably, many ionic liquid properties can be tuned in a wide range by structural modifications at their cation and anion. This review highlights specific examples of ionic liquid applications in catalysis and in separation technologies. Additionally, the application of ionic liquids as working fluids in process machines is introduced.

Use of ionic liquids as coordination ligands for organometallic catalysts

DOEpatents

Li, Zaiwei [Moreno Valley, CA; Tang, Yongchun [Walnut, CA; Cheng,; Jihong, [Arcadia, CA

2009-11-10

Aspects of the present invention relate to compositions and methods for the use of ionic liquids with dissolved metal compounds as catalysts for a variety of chemical reactions. Ionic liquids are salts that generally are liquids at room temperature, and are capable of dissolving a many types of compounds that are relatively insoluble in aqueous or organic solvent systems. Specifically, ionic liquids may dissolve metal compounds to produce homogeneous and heterogeneous organometallic catalysts. One industrially-important chemical reaction that may be catalyzed by metal-containing ionic liquid catalysts is the conversion of methane to methanol.

Electrical, structural, thermal and electrochemical properties of corn starch-based biopolymer electrolytes.

PubMed

Liew, Chiam-Wen; Ramesh, S

2015-06-25

Biopolymer electrolytes containing corn starch, lithium hexafluorophosphate (LiPF6) and ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate (BmImPF6) are prepared by solution casting technique. Temperature dependence-ionic conductivity studies reveal Vogel-Tamman-Fulcher (VTF) relationship which is associated with free volume theory. Ionic liquid-based biopolymer electrolytes show lower glass transition temperature (Tg) than ionic liquid-free biopolymer electrolyte. X-ray diffraction (XRD) studies demonstrate higher amorphous region of ionic liquid-added biopolymer electrolytes. In addition, the potential stability window of the biopolymer electrolyte becomes wider and stable up to 2.9V. Conclusively, the fabricated electric double layer capacitor (EDLC) shows improved electrochemical performance upon addition of ionic liquid into the biopolymer electrolyte. The specific capacitance of EDLC based on ionic liquid-added polymer electrolyte is relatively higher than that of ionic liquid-free polymer electrolyte as depicted in cyclic voltammogram. Copyright © 2015 Elsevier Ltd. All rights reserved.

Extraction of organic compounds with room temperature ionic liquids.

PubMed

Poole, Colin F; Poole, Salwa K

2010-04-16

Room temperature ionic liquids are novel solvents with a rather specific blend of physical and solution properties that makes them of interest for applications in separation science. They are good solvents for a wide range of compounds in which they behave as polar solvents. Their physical properties of note that distinguish them from conventional organic solvents are a negligible vapor pressure, high thermal stability, and relatively high viscosity. They can form biphasic systems with water or low polarity organic solvents and gases suitable for use in liquid-liquid and gas-liquid partition systems. An analysis of partition coefficients for varied compounds in these systems allows characterization of solvent selectivity using the solvation parameter model, which together with spectroscopic studies of solvent effects on probe substances, results in a detailed picture of solvent behavior. These studies indicate that the solution properties of ionic liquids are similar to those of polar organic solvents. Practical applications of ionic liquids in sample preparation include extractive distillation, aqueous biphasic systems, liquid-liquid extraction, liquid-phase microextraction, supported liquid membrane extraction, matrix solvents for headspace analysis, and micellar extraction. The specific advantages and limitations of ionic liquids in these studies is discussed with a view to defining future uses and the need not to neglect the identification of new room temperature ionic liquids with physical and solution properties tailored to the needs of specific sample preparation techniques. The defining feature of the special nature of ionic liquids is not their solution or physical properties viewed separately but their unique combinations when taken together compared with traditional organic solvents. Copyright 2009 Elsevier B.V. All rights reserved.

Theoretical and Numerical Modeling of faceted Ionic crystalline vesicles

NASA Astrophysics Data System (ADS)

Olvera de La Cruz, Monica

2007-03-01

Icosahedral shape is found in several natural structures including large viruses, large fullerenes and cationic-anionic vesicles. Faceting into icosahedral shape can occur in large crystalline membranes via elasticity theory. Icosahedral symmetry is found in small systems of particles with short-range interactions on a sphere. Dr G. Vernizzi and I show a novel electrostatic-driven mechanism of ionic crystalline shells faceting into icosahedral shapes even for systems with a small number of particles. Icosahedral shape is possible in cationic and anionic molecules adsorbed onto spherical interfaces, such as emulsions or other immiscible liquid droplets because the large concentration of charges at the interface can lead to ionic crystals on the curved interface. Such self-organized ionic structures favors the formation of flat surfaces. We find that these ionic crystalline shells can have lower energy when faceted into icosahedra along particular directions. Indeed, the ``ionic'' buckling is driven by preferred bending directions of the planar ionic structure, along which is more likely for the icosahedral shape to develop an edge. Since only certain orientations are allowed, rotational symmetry is broken. One can hope to exploit this mechanism to generate functional materials where, for instance, proteins with specific charge groups can orient at specific directions along an icosahedral cationic-anionic vesicle.

Objective Assessment of an Ionic Footbath (IonCleanse): Testing Its Ability to Remove Potentially Toxic Elements from the Body

PubMed Central

Kennedy, Deborah A.; Cooley, Kieran; Einarson, Thomas R.; Seely, Dugald

2012-01-01

Ionic footbaths are often used in holistic health centres and spas to aid in detoxification; however, claims that these machines eliminate toxins from the body have not been rigorously evaluated. In this proof-of-principle study, we sought to measure the release of potentially toxic elements from ionic footbaths into distilled and tap water with and without feet. Water samples were collected and analyzed following 30-minute ionic footbath sessions without feet using both distilled (n = 1) and tap water (n = 6) and following four ionic footbaths using tap water (once/week for 4 weeks) in six healthy participants. Urine collection samples were analyzed at four points during the study. Hair samples were analyzed for element concentrations at baseline and study conclusion. Contrary to claims made for the machine, there does not appear to be any specific induction of toxic element release through the feet when running the machine according to specifications. PMID:22174728

Ionic liquids as novel solvents for ionic polymer transducers

NASA Astrophysics Data System (ADS)

Bennett, Matthew D.; Leo, Donald J.

2004-07-01

The use of ionic liquids as solvents for ionic polymer (specifically, Nafion) transducers is demonstrated. Ionic liquids are attractive for this application because of their high inherent stability. Ionic liquids are salts that exist as liquids at room temperature and have no measureable vapor pressure. Therefore, the use of ionic liquids as solvents for ionic polymer transducers can eliminate the traditional problem of water evaporation in these devices. Another benefit of the use of ionic liquids in this way is the reduction or elimination of the characteristic back-relaxation common in water-solvated ionic polymer actuators. The results demonstrate that the viscosity of the ionic liquid and the degree to which the ionic liquid swells the membrane are the important physical parameters to consider. Five ionic liquids were studied, based on substituted pyrrolidinium, phosphonium, or imidazolium cations and fluoroanions. Of these five ionic liquids, transduction is demonstrated in three of them and the best results are obtained with 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ionic liquid. This substance has an electrochemical stability window of 4.1 V, a melting point of -10 °C, and a viscosity of 35-45 cP [19]. Results demonstrate that platinum-plated Nafion transducers solvated with this ionic liquid exhibit sensing and actuation responses and that these transducers are stable in air. Endurance testing of this sample reveals a decrease in the free strain of only 25 % after 250,000 actuation cycles in air.

Quantification of Cation Sorption to Engineered Barrier Materials Under Extreme Conditions

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

Powell, Brian; Schlautman, Mark; Rao, Linfeng

The objective of this research is to examine mechanisms and thermodynamics of actinide sorption to engineered barrier materials (iron (oxyhydr)oxides and bentonite clay) for nuclear waste repositories under high temperature and high ionic strength conditions using a suite of macroscopic and microscopic techniques which will be coupled with interfacial reaction models. Gaining a mechanistic understanding of interfacial processes governing the sorption/sequestration of actinides at mineral-water interfaces is fundamental for the accurate prediction of actinide behavior in waste repositories. Although macroscale sorption data and various spectroscopic techniques have provided valuable information regarding speciation of actinides at solid-water interfaces, significant knowledge gapsmore » still exist with respect to sorption mechanisms and the ability to quantify sorption, particularly at high temperatures and ionic strengths. This objective is addressed through three major tasks: (1) influence of oxidation state on actinide sorption to iron oxides and clay minerals at elevated temperatures and ionic strengths; (2) calorimetric titrations of actinide-mineral suspensions; (3) evaluation of bentonite performance under repository conditions. The results of the work will include a qualitative conceptual model and a quantitative thermodynamic speciation model describing actinide partitioning to minerals and sediments, which is based upon a mechanistic understanding of specific sorption processes as determined from both micro-scale and macroscale experimental techniques. The speciation model will be a thermodynamic aqueous and surface complexation model of actinide interactions with mineral surfaces that is self-consistent with macroscopic batch sorption data, calorimetric and potentiometric titrations, X-ray absorption Spectroscopy (XAS, mainly Extended X-ray Absorption Fine Structure (EXAFS)), and electron microscopy analyses. The novelty of the proposed work lies largely in the unique system conditions which will be examined (i.e. elevated temperature and ionic strength) and the manner in which the surface complexation model will be developed in terms of specific surface species identified using XAS. These experiments will thus provide a fundamental understanding of the chemical and physical processes occurring at the solid-solution interface under expected repository conditions. Additionally, the focus on thermodynamic treatment of actinide ion interactions with minerals as proposed will provide information on the driving forces involved and contribute to the overall understanding of the high affinity many actinide ions have for oxide surfaces. The utility of this model will be demonstrated in this work through a series of advective and diffusive flow experiments.« less

Ionic Liquids for Utilization of Waste Heat from Distributed Power Generation Systems

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

Joan F. Brennecke; Mihir Sen; Edward J. Maginn

2009-01-11

The objective of this research project was the development of ionic liquids to capture and utilize waste heat from distributed power generation systems. Ionic Liquids (ILs) are organic salts that are liquid at room temperature and they have the potential to make fundamental and far-reaching changes in the way we use energy. In particular, the focus of this project was fundamental research on the potential use of IL/CO2 mixtures in absorption-refrigeration systems. Such systems can provide cooling by utilizing waste heat from various sources, including distributed power generation. The basic objectives of the research were to design and synthesize ILsmore » appropriate for the task, to measure and model thermophysical properties and phase behavior of ILs and IL/CO2 mixtures, and to model the performance of IL/CO2 absorption-refrigeration systems.« less

Ionic liquids for addressing unmet needs in healthcare

PubMed Central

Agatemor, Christian; Ibsen, Kelly N.; Tanner, Eden E. L.

2018-01-01

Abstract Advances in the field of ionic liquids have opened new applications beyond their traditional use as solvents into other fields especially healthcare. The broad chemical space, rich with structurally diverse ions, and coupled with the flexibility to form complementary ion pairs enables task‐specific optimization at the molecular level to design ionic liquids for envisioned functions. Consequently, ionic liquids now are tailored as innovative solutions to address many problems in medicine. To date, ionic liquids have been designed to promote dissolution of poorly soluble drugs and disrupt physiological barriers to transport drugs to targeted sites. Also, their antimicrobial activity has been demonstrated and could be exploited to prevent and treat infectious diseases. Metal‐containing ionic liquids have also been designed and offer unique features due to incorporation of metals. Here, we review application‐driven investigations of ionic liquids in medicine with respect to current status and future potential. PMID:29376130

High energy supercapattery with an ionic liquid solution of LiClO4.

PubMed

Yu, Linpo; Chen, George Z

2016-08-15

A supercapattery combining an ideally polarized capacitor-like electrode and a battery-like electrode is demonstrated theoretically and practically using an ionic liquid electrolyte containing 1-butyl-1-methylpyrrolidinium tri(pentafluoroethyl)trifluorophosphate (BMPyrrFAP), gamma-butyrolactone (γ-GBL) and LiClO4. The electrochemical deposition and dissolution of lithium metal on a platinum and glass carbon electrode were investigated in this ionic liquid solution. The CVs showed that the fresh electrochemically deposited lithium metal was stable in the electrolyte, which encouraged the investigation of this ionic liquid solution in a supercapattery with a lithium battery negative electrode. The active material counted specific energy of the supercapattery based on a lithium negative electrode and an activated carbon (Act-C) positive electrode could reach 230 W h kg(-1) under a galvanostatic charge-discharge current density of 1 mA cm(-2). The positive electrode material (Act-C) was also investigated by CV, AC impedance, SEM and BET. The non-uniform particle size and micropores dominated porous structure of the Act-C enabled its electric double layer capacitor (EDLC) behavior in the ionic liquid solution. The measured specific capacitance of the Act-C in this ionic liquid solution is higher than the same Act-C in aqueous solution, which indicates the Act-C can also perform well in the ionic liquid electrolyte.

Recent advances of ionic liquids and polymeric ionic liquids in capillary electrophoresis and capillary electrochromatography.

PubMed

Tang, Sheng; Liu, Shujuan; Guo, Yong; Liu, Xia; Jiang, Shengxiang

2014-08-29

Ionic liquids (ILs) and polymeric ionic liquids (PILs) with unique and fascinating properties have drawn considerable interest for their use in separation science, especially in chromatographic techniques. In this article, significant contributions of ILs and PILs in the improvement of capillary electrophoresis and capillary electrochromatography are described, and a specific overview of the most relevant examples of their applications in the last five years is also given. Accordingly, some general conclusions and future perspectives in these areas are discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

Soft shape-adaptive gripping device made from artificial muscle

NASA Astrophysics Data System (ADS)

Hamburg, E.; Vunder, V.; Johanson, U.; Kaasik, F.; Aabloo, A.

2016-04-01

We report on a multifunctional four-finger gripper for soft robotics, suitable for performing delicate manipulation tasks. The gripping device is comprised of separately driven gripping and lifting mechanisms, both made from a separate single piece of smart material - ionic capacitive laminate (ICL) also known as artificial muscle. Compared to other similar devices the relatively high force output of the ICL material allows one to construct a device able to grab and lift objects exceeding multiple times its own weight. Due to flexible design of ICL grips, the device is able to adapt the complex shapes of different objects and allows grasping single or multiple objects simultaneously without damage. The performance of the gripper is evaluated in two different configurations: a) the ultimate grasping strength of the gripping hand; and b) the maximum lifting force of the lifting actuator. The ICL is composed of three main layers: a porous membrane consisting of non-ionic polymer poly(vinylidene fluoride-co-hexafluoropropene) (PVdF-HFP), ionic liquid 1-ethyl-3-methylimidazolium trifluoromethane-sulfonate (EMITFS), and a reinforcing layer of woven fiberglass cloth. Both sides of the membrane are coated with a carbonaceous electrode. The electrodes are additionally covered with thin gold layers, serving as current collectors. Device made of this material operates silently, requires low driving voltage (<3 V), and is suitable for performing tasks in open air environment.

Assessing the Potential Consequences of Subsurface Bioremediation: Fe-oxide Bioreductive Processes and the Propensity for Contaminant-colloid Co-transport and Media Structural Breakdown

DTIC Science & Technology

2017-05-12

were resolved by a technical approach that included three well-integrated experimental tasks follows: Task A: Quantify the impact of time- dependent ...aggregate breakdown and colloid dispersion depending on the extent of Fe(III) reduction and altered the pore structure and chemical reactivity of the porous...have significant effect on the transport of molecular and colloidal tracers (but not on the ionic tracer Br-) and colloid generation depending on

Supercapacitors based on modified graphene electrodes with poly(ionic liquid)

NASA Astrophysics Data System (ADS)

Trigueiro, João Paulo C.; Lavall, Rodrigo L.; Silva, Glaura G.

2014-06-01

The improved accessibility of the electrolyte to the surface of carbon nanomaterials is a challenge to be overcome in supercapacitors based on ionic liquid electrolytes. In this study, we report the preparation of supercapacitors based on reduced graphene oxide (RGO) electrodes and ionic liquid as the electrolyte (specifically, 1-methyl-1-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide or [MPPy][TFSI]). Two types of electrodes were compared: the RGO-based electrode and a poly(ionic liquid)-modified RGO electrode (PIL:RGO). The supercapacitor produced with the PIL:RGO electrode and [MPPy][TFSI] showed an electrochemical stability of 3 V and provided a capacitance of 71.5 F g-1 at room temperature; this capacitance is 130% higher with respect to the RGO-based supercapacitor. The decrease of the specific capacitance after 2000 cycles is only 10% for the PIL:RGO-based device. The results revealed the potential of the PIL:RGO material as an electrode for supercapacitors. This composite electrode increases the compatibility with the ionic liquid electrolyte compared to an RGO electrode, promoting an increase in the effective surface area of the electrode accessible to the electrolyte ions.

Morphological and electromechanical characterization of ionic liquid/Nafion polymer composites

NASA Astrophysics Data System (ADS)

Bennett, Matthew; Leo, Donald

2005-05-01

Ionic liquids have shown promise as replacements for water in ionic polymer transducers. Ionic liquids are non-volatile and have a larger electrochemical stability window than water. Therefore, transducers employing ionic liquids can be operated for long periods of time in air and can be actuated with higher voltages. Furthermore, transducers based on ionic liquids do not exhibit the characteristic back relaxation that is common with water-swollen materials. However, the physics of transduction in the ionic liquid-swollen materials is not well understood. In this paper, the morphology of Nafion/ionic liquid composites is characterized using small-angle X-ray scattering (SAXS). The electromechanical transduction behavior of the composites is also investigated. For this testing, five different counterions and two ionic liquids are used. The results reveal that both the morphology and transduction performance of the composites is affected by the identity of the ionic liquid, the cation, and the swelling level of ionic liquid within the membrane. Specifically, speed of response is found to be lower for the membranes that were exchanged with the smaller lithium and potassium ions. The response speed is also found to increase with increased content of ionic liquid. Furthermore, for the two ionic liquids studied, the actuators swollen with the less viscous ionic liquid exhibited a slower response. The slower speed of response corresponds to less contrast between the ionically conductive phase and the inert phase of the polymer. This suggests that disruption of the clustered morphology in the ionic liquid-swollen membranes as compared to water-swollen membranes attenuates ion mobility within the polymer. This attenuation is attributed to swelling of the non-conductive phase by the ionic liquids.

Effect of Ionic Soil Stabilizers on Soil-Water Characteristic of Special Clay

NASA Astrophysics Data System (ADS)

Cui, D.; Xiang, W.

2011-12-01

The engineering properties of special clay are conventionally improved through the use of chemical additive such as ionic soil stabilizer (ISS). Such special clays are often referred to as stabilized or treated clays. The soil-water characteristic curves (SWCC) of special clays from Henan province and Hubei province were measured both in natural and stabilized conditions using the pressure plate apparatus in the suction range of 0-500 kPa. The SWCC results are used to interpret the special clays behavior due to stabilizer treatment. In addition, relationships were developed between the basic clay and stabilized properties such as specific surface area and pore size distribution. The analysis showed that specific surface area decreases, cumulative pore volume and average pore size diameter decrease, dehydration rate slows and the thickness of water film thins after treatment with Ionic Soil Stabilizer. The research data and interpretation analysis presented here can be extended to understand the water film change behaviors influencing the mechanical and physical properties of stabilized special clay soils. KEY WORDS: ionic soil stabilizer, special clay, pore size diameter, specific surface area, soil water characteristic curve, water film

Elucidation of ionic interactions in the protic ionic liquid solutions by isothermal titration calorimetry.

PubMed

Rai, Gitanjali; Kumar, Anil

2014-04-17

The strong hydrogen-bonded network noted in protic ionic liquids (PILs) may lead to stronger interactions of the ionic entities of PILs with solvents (water, methanol, ethylene glycol, dimethylsulfoxide (DMSO), N,N'-dimethylformamide (DMF)) as compared with those of aprotic ionic liquids (APILs). The PILs used in this work are 1-methylimidazolium tetrafluoroborate, 2-methylpyridinium tetrafluoroborate, and N-methylpyrrolodinium tetrafluoroborate in comparison to 1-butyl-3-methylimidazolium tetrafluoroborate, which is classified as an APIL. In this work, the excess partial molar enthalpy, H(E)IL obtained from isothermal calorimetric titrations at 298.15 K is used to probe the nature of interactions of the PIL cations with solvent molecules against those present in APIL-solvent systems. This work also reports interesting flip-flopping in the thermal behavior of these PIL-solvent systems depending upon the structure of the cationic ring of a PIL. In some cases, these flip-flops are the specific fingerprints for specific PILs in a common solvent environment. The excess partial molar enthalpy at infinite dilution, H(E,∞)IL, of these PILs bears a critical dependence on the solvent properties. An analysis of relative apparent molar enthalpies, ϕL, of the PIL solutions by the ion interaction model of Pitzer yields important information on ionic interactions of these systems.

Predictive model for ionic liquid extraction solvents for rare earth elements

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

Grabda, Mariusz; Oleszek, Sylwia; Institute of Environmental Engineering of the Polish Academy of Sciences, ul. M. Sklodowskiej-Curie 34, 41-819, Zabrze

2015-12-31

The purpose of our study was to select the most effective ionic liquid extraction solvents for dysprosium (III) fluoride using a theoretical approach. Conductor-like Screening Model for Real Solvents (COSMO-RS), based on quantum chemistry and the statistical thermodynamics of predefined DyF{sub 3}-ionic liquid systems, was applied to reach the target. Chemical potentials of the salt were predicted in 4,400 different ionic liquids. On the base of these predictions set of ionic liquids’ ions, manifesting significant decrease of the chemical potentials, were selected. Considering the calculated physicochemical properties (hydrophobicity, viscosity) of the ionic liquids containing these specific ions, the most effectivemore » extraction solvents for liquid-liquid extraction of DyF{sub 3} were proposed. The obtained results indicate that the COSMO-RS approach can be applied to quickly screen the affinity of any rare earth element for a large number of ionic liquid systems, before extensive experimental tests.« less

Correlation between ion diffusional motion and ionic conductivity for different electrolytes based on ionic liquid.

PubMed

Kaur, Dilraj Preet; Yamada, K; Park, Jin-Soo; Sekhon, S S

2009-04-23

Room temperature ionic liquid 2,3-dimethyl-1-hexylimidazolium bis(trifluoromethane sulfonyl)imide (DMHxImTFSI) has been synthesized and used in the preparation of polymer gel electrolytes containing polymethylmethacrylate and propylene carbonate (PC). The onset of ion diffusional motion has been studied by (1)H and (19)F NMR spectroscopy and the results obtained for ionic liquid, liquid electrolytes, and polymer gel electrolytes have been correlated with the ionic conductivity results for these electrolytes in the 100-400 K temperature range. The temperature at which (1)H and (19)F NMR lines show motional narrowing and hence ion diffusional motion starts has been found to be closely related to the temperature at which a large increase in ionic conductivity has been observed for these electrolytes. Polymer gel electrolytes have high ionic conductivity over a wide range of temperatures. Thermogravimetric analysis/differential scanning calorimetry studies show that the ionic liquid (DMHxImTFSI) used in the present study is thermally stable up to 400 degrees C, whereas the addition of PC lowers the thermal stability of polymer gel electrolytes containing the ionic liquid. Different electrolytes have been observed to show high ionic conductivity in different range of temperatures, which can be helpful in the design of polymer gel electrolytes for specific applications.

New insight into the environmental impact of two imidazolium ionic liquids. Effects on seed germination and soil microbial activity.

PubMed

Salgado, J; Parajó, J J; Teijeira, T; Cruz, O; Proupín, J; Villanueva, M; Rodríguez-Añón, J A; Verdes, P V; Reyes, O

2017-10-01

The next generation of ionic liquids must be synthetized taking into account structures that guarantee the suitable properties for a defined application as well as ecological data. Thus, searching of the right methodologies to know, quickly and efficiently, the ecological effects of these compounds is a preliminary task. The effects of two imidazolium based ionic liquids with different anions, 1-butyl-3-methylimidazolium tetrafluoroborate, [C 4 C 1 Im][BF 4 ], and 1-propyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C 3 C 1 Im][NTf 2 ], on seedling emergence of six tree species and on the microbial behaviour of two soils were determined in this work. Results showed that the highest doses of both ionic liquids caused the total inhibition of germination for almost all the species studied and that the seeds are more sensitive to the presence of these compounds than soil microbial activity. Nevertheless, signals of stress and death are observed from the results of heat released by microorganisms after the addition of the highest doses of both ionic liquids. The novelty of this work resides in the enlargement of knowledge of toxicity of ILs on complex organisms such as arboreal species and microbial activity of soils studied for the first time through a microcalorimetric technique. Copyright © 2017 Elsevier Ltd. All rights reserved.

Ionic liquid-based extraction followed by graphite-furnace atomic absorption spectrometry for the determination of trace heavy metals in high-purity iron metal.

PubMed

Matsumiya, Hiroaki; Kato, Tatsuya; Hiraide, Masataka

2014-02-01

The analysis of high-purity materials for trace impurities is an important and challenging task. The present paper describes a facile and sensitive method for the determination of trace heavy metals in high-purity iron metal. Trace heavy metals in an iron sample solution were rapidly and selectively preconcentrated by the extraction into a tiny volume of an ionic liquid [1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide] for the determination by graphite-furnace atomic absorption spectrometry (GFAAS). A nitrogen-donating neutral ligand, 2,4,6-tris(2-pyridyl)-1,3,5-triazine (TPTZ), was found to be effective in the ionic liquid-based selective extraction, allowing the nearly complete (~99.8%) elimination of the iron matrix. The combination with the optimized GFAAS was successful. The detectability reached sub-μg g(-1) levels in iron metal. The novel use of TPTZ in ionic liquid-based extraction followed by GFAAS was successfully applied to the determination of traces of Co, Ni, Cu, Cd, and Pb in certified reference materials for high-purity iron metal. © 2013 Published by Elsevier B.V.

Modeling electrokinetics in ionic liquids: General

DOE PAGES

Wang, Chao; Bao, Jie; Pan, Wenxiao; ...

2017-04-01

Using direct numerical simulations, we provide a thorough study regarding the electrokinetics of ionic liquids. In particular, modified Poisson–Nernst–Planck equations are solved to capture the crowding and overscreening effects characteristic of an ionic liquid. For modeling electrokinetic flows in an ionic liquid, the modified Poisson-Nernst-Planck equations are coupled with Navier–Stokes equations to study the coupling of ion transport, hydrodynamics, and electrostatic forces. Specifically, we consider the ion transport between two parallel charged surfaces, charging dynamics in a nanopore, capacitance of electric double-layer capacitors, electroosmotic flow in a nanochannel, electroconvective instability on a plane ion-selective surface, and electroconvective flow on amore » curved ionselective surface. Lastly, we also discuss how crowding and overscreening and their interplay affect the electrokinetic behaviors of ionic liquids in these application problems.« less

Performance of carbon-carbon supercapacitors based on organic, aqueous and ionic liquid electrolytes

NASA Astrophysics Data System (ADS)

Lewandowski, Andrzej; Olejniczak, Angelika; Galinski, Maciej; Stepniak, Izabela

Properties of capacitors working with the same carbon electrodes (activated carbon cloth) and three types of electrolytes: aqueous, organic and ionic liquids were compared. Capacitors filled with ionic liquids worked at a potential difference of 3.5 V, their solutions in AN and PC were charged up to the potential difference of 3 V, classical organic systems to 2.5 V and aqueous to 1 V. Cyclic voltammetry, galvanostatic charging/discharging and impedance spectroscopy were used to characterize these capacitors. The highest specific energy was recorded for the device working with ionic liquids, while the highest power is characteristic for the device filled with aqueous H 2SO 4 electrolyte. Aqueous electrolytes led to energy density an order of magnitude lower in comparison to that characteristic of ionic liquids.

Thioimidazolium Ionic Liquids as Tunable Alkylating Agents.

PubMed

Guterman, Ryan; Miao, Han; Antonietti, Markus

2018-01-19

Alkylating ionic liquids based on the thioimidazolium structure combine the conventional properties of ionic liquids, including low melting point and nonvolatility, with the alkylating function. Alkyl transfer occurs exclusively from the S-alkyl position, thus allowing for easy derivatization of the structure without compromising specificity. We apply this feature to tune the electrophilicty of the cation to profoundly affect the reactivity of these alkylating ionic liquids, with a caffeine-derived compound possessing the highest reactivity. Anion choice was found to affect reaction rates, with iodide anions assisting in the alkylation reaction through a "shuttling" process. The ability to tune the properties of the alkylating agent using the toolbox of ionic liquid chemistry highlights the modular nature of these compounds as a platform for alkylating agent design and integration in to future systems.

Go Chemistry: A Card Game to Help Students Learn Chemical Formulas

ERIC Educational Resources Information Center

Morris, Todd A.

2011-01-01

For beginning chemistry students, the basic tasks of writing chemical formulas and naming covalent and ionic compounds often pose difficulties and are only sufficiently grasped after extensive practice with homework sets. An enjoyable card game that can replace or, at least, complement nomenclature homework sets is described. "Go Chemistry" is…

The effects of high concentrations of ionic liquid on GB1 protein structure and dynamics probed by high-resolution magic-angle-spinning NMR spectroscopy.

PubMed

Warner, Lisa; Gjersing, Erica; Follett, Shelby E; Elliott, K Wade; Dzyuba, Sergei V; Varga, Krisztina

2016-12-01

Ionic liquids have great potential in biological applications and biocatalysis, as some ionic liquids can stabilize proteins and enhance enzyme activity, while others have the opposite effect. However, on the molecular level, probing ionic liquid interactions with proteins, especially in solutions containing high concentration of ionic liquids, has been challenging. In the present work the 13 C, 15 N-enriched GB1 model protein was used to demonstrate applicability of high-resolution magic-angle-spinning (HR-MAS) NMR spectroscopy to investigate ionic liquid - protein interactions. Effect of an ionic liquid (1-butyl-3-methylimidazolium bromide, [C 4 -mim]Br) on GB1was studied over a wide range of the ionic liquid concentrations (0.6 to 3.5 M, which corresponds to 10%-60% v/v). Interactions between GB1 and [C 4 -mim]Br were observed from changes in the chemical shifts of the protein backbone as well as the changes in 15 N ps-ns dynamics and rotational correlation times. Site-specific interactions between the protein and [C 4 -mim]Br were assigned using 3D methods under HR-MAS conditions. Thus, HR-MAS NMR is a viable tool that could aid in elucidation of the molecular mechanism of ionic liquid - protein interactions.

Predicting ion specific capacitances of supercapacitors due to quantum ionic interactions.

PubMed

Parsons, Drew F

2014-08-01

A new theoretical framework is now available to help explain ion specific (Hofmeister) effects. All measurements in physical chemistry show ion specificity, inexplicable by classical electrostatic theories. These ignore ionic dispersion forces that change ionic adsorption. We explored ion specificity in supercapacitors using a modified Poisson-Boltzmann approach that includes ionic dispersion energies. We have applied ab initio quantum chemical methods to determine required ion sizes and ion polarisabilities. Our model represents graphite electrodes through their optical dielectric spectra. The electrolyte was 1.2 M Li salt in propylene carbonate, using the common battery anions, PF6(-), BF4(-) and ClO4(-). We also investigated the perhalate series with BrO4(-) and IO4(-). The capacitance C=dσ/dψ was calculated from the predicted electrode surface charge σ of each electrode with potential ψ between electrodes. Compared to the purely electrostatic calculation, the capacitance of a positively charged graphite electrode was enhanced by more than 15%, with PF6(-) showing >50% increase in capacitance. IO4(-) provided minimal enhancement. The enhancement is due to adsorption of both anions and cations, driven by ionic dispersion forces. The Hofmeister series in the single-electrode capacitance was PF6(-)>BF4(-)>ClO4(-)>BrO4(-)>IO4(-) . When the graphite electrode was negatively charged, the perhalates provided almost no enhancement of capacitance, while PF6(-) and BF4(-) decreased capacitance by about 15%. Due to the asymmetric impact of nonelectrostatic ion interactions, the capacitances of positive and negative electrodes are not equal. The capacitance of a supercapacitor should therefore be reported as two values rather than one, similar to the matrix of mutual capacitances used in multielectrode devices. Copyright © 2014 Elsevier Inc. All rights reserved.

Sensitivities of ionic explosives

NASA Astrophysics Data System (ADS)

Politzer, Peter; Lane, Pat; Murray, Jane S.

2017-03-01

We have investigated the relevance for ionic explosive sensitivity of three factors that have been demonstrated to be related to the sensitivities of molecular explosives. These are (1) the maximum available heat of detonation, (2) the amount of free space per molecule (or per formula unit) in the crystal lattice and (3) specific features of the electrostatic potential on the molecular or ionic surface. We find that for ionic explosives, just as for molecular ones, there is an overall tendency for impact sensitivity to increase as the maximum detonation heat release is greater. This means that the usual emphasis upon designing explosives with large heats of detonation needs to be tempered somewhat. We also show that a moderate detonation heat release does not preclude a high level of detonation performance for ionic explosives, as was already demonstrated for molecular ones. Relating the free space per formula unit to sensitivity may require a modified procedure for ionic explosives; this will continue to be investigated. Finally, an encouraging start has been made in linking impact sensitivities to the electrostatic potentials on ionic surfaces, although limited so far to ammonium salts.

Modeling electrokinetics in ionic liquids: General

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

Wang, Chao; Bao, Jie; Pan, Wenxiao

2017-04-07

Using direct numerical simulations we provide a thorough study on the electrokinetics of ionic liquids. In particular, the modfied Poisson-Nernst-Planck (MPNP) equations are solved to capture the crowding and overscreening effects that are the characteristics of an ionic liquid. For modeling electrokinetic flows in an ionic liquid, the MPNP equations are coupled with the Navier-Stokes equations to study the coupling of ion transport, hydrodynamics, and electrostatic forces. Specifically, we consider the ion transport between two parallel plates, charging dynamics in a 2D straight-walled pore, electro-osmotic ow in a nano-channel, electroconvective instability on a plane ion-selective surface, and electroconvective ow onmore » a curved ion-selective surface. We discuss how the crowding and overscreening effects and their interplay affect the electrokinetic behaviors of ionic liquids in these application problems.« less

Key Developments in Ionic Liquid Crystals.

PubMed

Alvarez Fernandez, Alexandra; Kouwer, Paul H J

2016-05-16

Ionic liquid crystals are materials that combine the classes of liquid crystals and ionic liquids. The first one is based on the multi-billion-dollar flat panel display industry, whilst the latter quickly developed in the past decades into a family of highly-tunable non-volatile solvents. The combination yields materials with a unique set of properties, but also with many challenges ahead. In this review, we provide an overview of the key concepts in ionic liquid crystals, particularly from a molecular perspective. What are the important molecular parameters that determine the phase behavior? How should they be introduced into the molecules? Finally, which other tools does one have to realize specific properties in the material?

Key Developments in Ionic Liquid Crystals

PubMed Central

Alvarez Fernandez, Alexandra; Kouwer, Paul H. J.

2016-01-01

Ionic liquid crystals are materials that combine the classes of liquid crystals and ionic liquids. The first one is based on the multi-billion-dollar flat panel display industry, whilst the latter quickly developed in the past decades into a family of highly-tunable non-volatile solvents. The combination yields materials with a unique set of properties, but also with many challenges ahead. In this review, we provide an overview of the key concepts in ionic liquid crystals, particularly from a molecular perspective. What are the important molecular parameters that determine the phase behavior? How should they be introduced into the molecules? Finally, which other tools does one have to realize specific properties in the material? PMID:27196890

Predicting critical temperatures of ionic and non-ionic fluids from thermophysical data obtained near the melting point.

PubMed

Weiss, Volker C

2015-10-14

In the correlation and prediction of thermophysical data of fluids based on a corresponding-states approach, the critical temperature Tc plays a central role. For some fluids, in particular ionic ones, however, the critical region is difficult or even impossible to access experimentally. For molten salts, Tc is on the order of 3000 K, which makes accurate measurements a challenging task. Room temperature ionic liquids (RTILs) decompose thermally between 400 K and 600 K due to their organic constituents; this range of temperatures is hundreds of degrees below recent estimates of their Tc. In both cases, reliable methods to deduce Tc based on extrapolations of experimental data recorded at much lower temperatures near the triple or melting points are needed and useful because the critical point influences the fluid's behavior in the entire liquid region. Here, we propose to employ the scaling approach leading to universal fluid behavior [Román et al., J. Chem. Phys. 123, 124512 (2005)] to derive a very simple expression that allows one to estimate Tc from the density of the liquid, the surface tension, or the enthalpy of vaporization measured in a very narrow range of low temperatures. We demonstrate the validity of the approach for simple and polar neutral fluids, for which Tc is known, and then use the methodology to obtain estimates of Tc for ionic fluids. When comparing these estimates to those reported in the literature, good agreement is found for RTILs, whereas the ones for the molten salts NaCl and KCl are lower than previous estimates by 10%. The coexistence curve for ionic fluids is found to be more adequately described by an effective exponent of βeff = 0.5 than by βeff = 0.33.

Development of solvent-free ambient mass spectrometry for green chemistry applications.

PubMed

Liu, Pengyuan; Forni, Amanda; Chen, Hao

2014-04-15

Green chemistry minimizes chemical process hazards in many ways, including eliminating traditional solvents or using alternative recyclable solvents such as ionic liquids. This concept is now adopted in this study for monitoring solvent-free reactions and analysis of ionic liquids, solids, and catalysts by mass spectrometry (MS), without using any solvent. In our approach, probe electrospray ionization (PESI), an ambient ionization method, was employed for this purpose. Neat viscous room-temperature ionic liquids (RTILs) in trace amounts (e.g., 25 nL) could be directly analyzed without sample carryover effect, thereby enabling high-throughput analysis. With the probe being heated, it can also ionize ionic solid compounds such as organometallic complexes as well as a variety of neat neutral solid chemicals (e.g., amines). More importantly, moisture-sensitive samples (e.g., [bmim][AlCl4]) can be successfully ionized. Furthermore, detection of organometallic catalysts (including air-sensitive [Rh-MeDuPHOS][OTf]) in ionic liquids, a traditionally challenging task due to strong ion suppression effect from ionic liquids, can be enabled using PESI. In addition, PESI can be an ideal approach for monitoring solvent-free reactions. Using PESI-MS, we successfully examined the alkylation of amines by alcohols, the conversion of pyrylium into pyridinium, and the condensation of aldehydes with indoles as well as air- and moisture-sensitive reactions such as the oxidation of ferrocene and the condensation of pyrazoles with borohydride. Interestingly, besides the expected reaction products, the reaction intermediates such as the monopyrazolylborate ion were also observed, providing insightful information for reaction mechanisms. We believe that the presented solvent-free PESI-MS method would impact the green chemistry field.

Amino acid ionic liquids as chiral ligands in ligand-exchange chiral separations.

PubMed

Liu, Qian; Wu, Kangkang; Tang, Fei; Yao, Lihua; Yang, Fei; Nie, Zhou; Yao, Shouzhuo

2009-09-28

Recently, amino acid ionic liquids (AAILs) have attracted much research interest. In this paper, we present the first application of AAILs in chiral separation based on the chiral ligand exchange principle. By using 1-alkyl-3-methylimidazolium L-proline (L-Pro) as a chiral ligand coordinated with copper(II), four pairs of underivatized amino acid enantiomers-dl-phenylalanine (dl-Phe), dl-histidine (dl-His), dl-tryptophane (dl-Trp), and dl-tyrosine (dl-Tyr)-were successfully separated in two major chiral separation techniques, HPLC and capillary electrophoresis (CE), with higher enantioselectivity than conventionally used amino acid ligands (resolution (R(s))=3.26-10.81 for HPLC; R(s)=1.34-4.27 for CE). Interestingly, increasing the alkyl chain length of the AAIL cation remarkably enhanced the enantioselectivity. It was inferred that the alkylmethylimidazolium cations and L-Pro form ion pairs on the surface of the stationary phase or on the inner surface of the capillary. The ternary copper complexes with L-Pro are consequently attached to the support surface, thus inducing an ion-exchange type of retention for the dl-enantiomers. Therefore, the AAIL cation plays an essential role in the separation. This work demonstrates that AAILs are good alternatives to conventional amino acid ligands for ligand-exchange-based chiral separation. It also reveals the tremendous application potential of this new type of task-specific ILs.

Physics of transduction in ionic liquid-swollen Nafion membranes

NASA Astrophysics Data System (ADS)

Bennett, Matthew; Leo, Donald

2006-03-01

Ionic polymer transducers are a class of electroactive polymers that are able to generate large strains (1-5%) in response to low voltage inputs (1-5 V). Additionally, these materials generate electrical charge in response to mechanical strain and are therefore able to operate as soft, distributed sensors. Traditionally, ionic polymer transducers have been limited in their application by their hydration dependence. This work seeks to overcome this limitation by replacing the water with an ionic liquid. Ionic liquids are molten salts that exhibit very high thermal and electrochemical stability while also possessing high ionic conductivity. Results have shown that an ionic liquid-swollen ionic polymer transducer can operate for more than 250,000 cycles in air as compared to about 2,000 cycles for a water-swollen transducer. The current work examines the mechanisms of transduction in ionic liquid-swollen transducers based on Nafion polymer membranes. Specifically, the morphology and relevant ion associations within these membranes are investigated by the use of small-angle X-ray scattering (SAXS), Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance spectroscopy (NMR). These results reveal that the ionic liquid interacts with the membrane in much the same way that water does, and that the counterions of the Nafion polymer are the primary charge carriers. The results of these analyses are compared to the macroscopic transduction behavior in order to develop a model of the charge transport mechanism responsible for electromechanical coupling in these membranes.

The effects of high concentrations of ionic liquid on GB1 protein structure and dynamics probed by high-resolution magic-angle-spinning NMR spectroscopy

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

Warner, Lisa; Gjersing, Erica; Follett, Shelby E.

Ionic liquids have great potential in biological applications and biocatalysis, as some ionic liquids can stabilize proteins and enhance enzyme activity, while others have the opposite effect. However, on the molecular level, probing ionic liquid interactions with proteins, especially in solutions containing high concentrations of ionic liquids, has been challenging. In the present work the 13C, 15N-enriched GB1 model protein was used to demonstrate applicability of high-resolution magic-angle-spinning (HR-MAS) NMR spectroscopy to investigate ionic liquid-protein interactions. Effect of an ionic liquid (1-butyl-3-methylimidazolium bromide, [C 4-mim]Br) on GB1was studied over a wide range of the ionic liquid concentrations (0.6-3.5 M, whichmore » corresponds to 10-60% v/v). Interactions between GB1 and [C 4-mim]Br were observed from changes in the chemical shifts of the protein backbone as well as the changes in 15N ps-ns dynamics and rotational correlation times. Site-specific interactions between the protein and [C 4-mim]Br were assigned using 3D methods under HR-MAS conditions. Furthermore, HR-MAS NMR is a viable tool that could aid in elucidation of molecular mechanisms of ionic liquid-protein interactions.« less

The effects of high concentrations of ionic liquid on GB1 protein structure and dynamics probed by high-resolution magic-angle-spinning NMR spectroscopy

DOE PAGES

Warner, Lisa; Gjersing, Erica; Follett, Shelby E.; ...

2016-08-11

Ionic liquids have great potential in biological applications and biocatalysis, as some ionic liquids can stabilize proteins and enhance enzyme activity, while others have the opposite effect. However, on the molecular level, probing ionic liquid interactions with proteins, especially in solutions containing high concentrations of ionic liquids, has been challenging. In the present work the 13C, 15N-enriched GB1 model protein was used to demonstrate applicability of high-resolution magic-angle-spinning (HR-MAS) NMR spectroscopy to investigate ionic liquid-protein interactions. Effect of an ionic liquid (1-butyl-3-methylimidazolium bromide, [C 4-mim]Br) on GB1was studied over a wide range of the ionic liquid concentrations (0.6-3.5 M, whichmore » corresponds to 10-60% v/v). Interactions between GB1 and [C 4-mim]Br were observed from changes in the chemical shifts of the protein backbone as well as the changes in 15N ps-ns dynamics and rotational correlation times. Site-specific interactions between the protein and [C 4-mim]Br were assigned using 3D methods under HR-MAS conditions. Furthermore, HR-MAS NMR is a viable tool that could aid in elucidation of molecular mechanisms of ionic liquid-protein interactions.« less

Dissecting ion-specific from electrostatic salt effects on amyloid fibrillation: A case study of insulin.

PubMed

Kutsch, Miriam; Hortmann, Pascal; Herrmann, Christian; Weibels, Sebastian; Weingärtner, Hermann

2016-03-03

Diseases like Alzheimer, type II diabetes mellitus, and others go back to fibril formation of partially unfolded proteins. The impact of sodium, potassium, choline, guanidinium, and 1-ethyl-3-methylimidazolium chloride on the fibrillation kinetics of insulin in an acid-denaturing solvent environment is studied by fluorescence spectroscopy using thioflavin T as a fibril-specific stain. The fibrillation kinetics reveal a sigmoidal behavior, characterized by the lag time τlag and the maximum elongation rate k of the fibrils. Up to ionic strengths of about 70 mM, the elongation rate increases with salt concentration. This increase is nonspecific with regard to the salts. Below ionic strengths of ∼50 mM, it can be explained by a Debye-Hückel type model, indicating a dominant role of Coulomb interactions between the charged reactants and products screened by the ionic environment. At higher ionic strength, the elongation rates pass maxima, followed by a Hofmeister type ion-specific decrease. There is a correlation between the lag time τlag and the inverse elongation rate k, which can be described by a power law of the form τlag ∝  aτ(α) with a sublinear exponent α ≅ 1/2.

Numerical modeling of ultrasonic cavitation in ionic liquids

NASA Astrophysics Data System (ADS)

Calvisi, Michael L.; Elder, Ross M.

2017-11-01

Ionic liquids have favorable properties for sonochemistry applications in which the high temperatures and pressures achieved by cavitation bubbles are important drivers of chemical processes. Two different numerical models are presented to simulate ultrasonic cavitation in ionic liquids, each with different capabilities and physical assumptions. A model based on a compressible form of the Rayleigh-Plesset equation (RPE) simulates ultrasonic cavitation of a spherical bubble with a homogeneous interior, incorporating evaporation and condensation at the bubble surface, and temperature-varying thermodynamic properties in the interior. A second, more computationally intensive model of a spherical bubble uses the finite element method (FEM) and accounts for spatial variations in pressure and temperature throughout the flow domain. This model provides insight into heat transfer across the bubble surface and throughout the bubble interior and exterior. Parametric studies are presented for sonochemistry applications involving ionic liquids as a solvent, examining a range of realistic ionic liquid properties and initial conditions to determine their effect on temperature and pressure. Results from the two models are presented for parametric variations including viscosity, thermal conductivity, water content of the ionic liquid solvent, acoustic frequency, and initial bubble pressure. An additional study performed with the FEM model examines thermal penetration into the surrounding ionic liquid during bubble oscillation. The results suggest the prospect of tuning ionic liquid properties for specific applications.

Atomistic Simulation of Interfaces in Materials of Solid State Ionics

NASA Astrophysics Data System (ADS)

Ivanov-Schitz, A. K.; Mazo, G. N.

2018-01-01

The possibilities of describing correctly interfaces of different types in solids within a computer experiment using molecular statics simulation, molecular dynamics simulation, and quantum chemical calculations are discussed. Heterophase boundaries of various types, including grain boundaries and solid electrolyte‒solid electrolyte and ionic conductor‒electrode material interfaces, are considered. Specific microstructural features and mechanisms of the ion transport in real heterophase structures (cationic conductor‒metal anode and anionic conductor‒cathode) existing in solid state ionics devices (such as solid-state batteries and fuel cells) are discussed.

Annual Report - Compatibility of ZDDP and ionic liquid anti-wear additives with hard coatings for engine lubrications

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

Qu, Jun; Zhou, Yan; Leonard, Donovan N

The objectives for this considerations described here are to; investigate the compatibility of engine lubricant antiwear (AW) additives, specifically conventional zinc dialkyldithiophosphate (ZDDP) and newly developed ionic liquids (ILs), with selected commercial hard coatings, and provide fundamental understanding to guide future development of engine lubricants.

Ionic Liquid Catalyzed Electrolyte for Electrochemical Polyaniline Supercapacitors

NASA Astrophysics Data System (ADS)

Inamdar, A. I.; Im, Hyunsik; Jung, Woong; Kim, Hyungsang; Kim, Byungchul; Yu, Kook-Hyun; Kim, Jin-Sang; Hwang, Sung-Min

2013-05-01

The effect of different wt.% of ionic liquid "1,6-bis (trimethylammonium-1-yl) hexane tetrafluoroborate" in 0.5 M LiClO4+PC electrolyte on the supercapacitor properties of polyaniline (PANI) thin film are investigated. The PANI film is synthesized using electropolymerization of aniline in the presence of sulfuric acid. The electrochemical properties of the PANI thin film are studied by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS) measurements. The optimum amount of the ionic liquid is found to be 2 wt.% which provides better ionic conductivity of the electrolyte. The highest specific capacitance of 259 F/g is obtained using the 2 wt.% electrolyte. This capacitance remains at up to 208 F/g (80% capacity retention) after 1000 charge-discharge cycles at a current density of 0.5 mA/g. The PANI film in the 2 wt.% ionic liquid catalyzed 0.5 M LiClO4+PC electrolyte shows small electrochemical resistance, better rate performance and higher cyclability. The increased ionic conductivity of the 2 wt.% ionic liquid catalyzed electrolyte causes a reduction in resistance at the electrode/electrolyte interface, which can be useful in electrochemically-preferred power devices for better applicability.

A mean-density model of ionic surfactants for the dispersion of carbon nanotubes in aqueous solutions

NASA Astrophysics Data System (ADS)

Joung, Young Soo

2018-05-01

We propose a new analytical model of ionic surfactants used for the dispersion of carbon nanotubes (CNTs) in aqueous solutions. Although ionic surfactants are commonly used to facilitate the dispersion of CNTs in aqueous solutions, understanding the dispersion process is challenging and time-consuming owing to its complexity and nonlinearity. In this work, we develop a mean-density model of ionic surfactants to simplify the calculation of interaction forces between CNTs stabilized by ionic surfactants. Using this model, we can evaluate various interaction forces between the CNTs and ionic surfactants under different conditions. The dispersion mechanism is investigated by estimating the potential of mean force (PMF) as a function of van der Waals forces, electrostatic forces, interfacial tension, and osmotic pressure. To verify the proposed model, we compare the PMFs derived using our method with those derived from molecular dynamics simulations using comparable CNTs and ionic surfactants. Notably, for stable dispersions, the osmotic pressure and interfacial energy are important for long-range and short-range interactions, respectively, in comparison with the effect of electrostatic forces. Our model effectively prescribes specific surfactants and their concentrations to achieve stable aqueous suspensions of CNTs.

Student Conceptions of Ionic Bonding: Patterns of thinking across three European contexts

NASA Astrophysics Data System (ADS)

Taber, Keith S.; Tsaparlis, Georgios; Nakiboğlu, Canan

2012-12-01

Previous research has reported that students commonly develop alternative conceptions in the core topic of chemical bonding. Research in England has reported that students there commonly demonstrate an alternative 'molecular' conceptual framework for thinking about ionic bonding: in terms of the formation of molecule-like ions pairs through electron transfer, which are internally bonded, but not bonded to other ions. The present study reports the use of translated versions of a diagnostic instrument to elicit the conceptions of bonding in NaCl (commonly used as the teaching example of an ionic compound) from two samples of students setting out on university courses in Greece and Turkey. The study reports that students in these two contexts displayed high levels of support for statements based upon the alternative conceptual framework identified in the English context. Students commonly develop similar alternative conceptions of ionic bonding in these three different educational contexts. The study also found some quite large differences in the specific response patterns across these three contexts, some of which could reflect specific features of the different curriculum contexts. The study reinforces the cross-national nature of the challenge of effectively teaching the abstract models of chemistry at the submicroscopic level. It also provides intriguing suggestions that a close study of the interactions between specific curriculum contexts and specific patterns in students' thinking offers much potential for identifying particular aspects of subject pedagogy that either support or impede the learning of accepted scientific models.

Ionic calcium determination in skim milk with molecular probes and front-face fluorescence spectroscopy: simple linear regression.

PubMed

Gangidi, R R; Metzger, L E

2006-11-01

The purpose of this study was to determine if the ionic calcium content of skim milk could be determined using molecular probes and front-face fluorescence spectroscopy. Current methods for determining ionic calcium are not sensitive, overestimate ionic calcium, or require complex procedures. Molecular probes designed specifically for measuring ionic calcium could potentially be used to determine the ionic calcium content of skim milk. The goal of the current study was to develop foundation methods for future studies to determine ionic calcium directly in skim milk and other dairy products with molecular probes and fluorescence spectroscopy. In this study, the effect of pH on calcium-sensitive fluorescent probe (Rhod-5N and Fluo-5N) performance using various concentrations of skim milk was determined. The pH of diluted skim milk (1.9 to 8.9% skim milk), was adjusted to either 6.2 or 7.0, after which the samples were analyzed with fluorescent probes (1 microM) and front-face fluorescence spectroscopy. The ionic calcium content of each sample was also determined using a calcium ion-selective electrode. The results demonstrated that the ionic calcium content of each sample was highly correlated (R2 > 0.989) with the fluorescence intensities of the probe-calcium adduct using simple linear regression. Higher than suggested ionic calcium contents of 1,207 and 1,973 microM were determined with the probes (Fluo-5N and Rhod-5N) in diluted skim milk with pH 7.0 and 6.2, respectively. The fluorescence intensity of the probe-calcium adduct decreased with a decrease in pH for the same ionic calcium concentration. This study demonstrates that Fluo-5N and Rhod-5N can be used to determine the ionic-calcium content of diluted milk with front-face fluorescence spectroscopy. Furthermore, these probes may also have the potential to determine the ionic calcium content of undiluted skim milk.

Optimum Water Chemistry in radiation field buildup control

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

Lin, Chien, C.

1995-03-01

Nuclear utilities continue to face the challenGE of reducing exposure of plant maintenance personnel. GE Nuclear Energy has developed the concept of Optimum Water Chemistry (OWC) to reduce the radiation field buildup and minimize the radioactive waste production. It is believed that reduction of radioactive sources and improvement of the water chemistry quality should significantly reduce both the radiation exposure and radwaste production. The most important source of radioactivity is cobalt and replacement of cobalt containing alloy in the core region as well as in the entire primary system is considered the first priority to achieve the goal of lowmore » exposure and minimized waste production. A plant specific computerized cobalt transport model has been developed to evaluate various options in a BWR system under specific conditions. Reduction of iron input and maintaining low ionic impurities in the coolant have been identified as two major tasks for operators. Addition of depleted zinc is a proven technique to reduce Co-60 in reactor water and on out-of-core piping surfaces. The effect of HWC on Co-60 transport in the primary system will also be discussed.« less

What the cognitive neurosciences mean to me.

PubMed

Pereira, Alfredo

2007-01-01

Cognitive Neuroscience is an interdisciplinary area of research that combines measurement of brain activity (mostly by means of neuroimaging) with a simultaneous performance of cognitive tasks by human subjects. These investigations have been successful in the task of connecting the sciences of the brain (Neurosciences) and the sciences of the mind (Cognitive Sciences). Advances on this kind of research provide a map of localization of cognitive functions in the human brain. Do these results help us to understand how mind relates to the brain? In my view, the results obtained by the Cognitive Neurosciences lead to new investigations in the domain of Molecular Neurobiology, aimed at discovering biophysical mechanisms that generate the activity measured by neuroimaging instruments. In this context, I argue that the understanding of how ionic/molecular processes support cognition and consciousness cannot be made by means of the standard reductionist explanations. Knowledge of ionic/molecular mechanisms can contribute to our understanding of the human mind as long as we assume an alternative form of explanation, based on psycho-physical similarities, together with an ontological view of mentality and spirituality as embedded in physical nature (and not outside nature, as frequently assumed in western culture).

What The Cognitive Neurosciences Mean To Me

PubMed Central

Pereira, Alfredo

2007-01-01

Cognitive Neuroscience is an interdisciplinary area of research that combines measurement of brain activity (mostly by means of neuroimaging) with a simultaneous performance of cognitive tasks by human subjects. These investigations have been successful in the task of connecting the sciences of the brain (Neurosciences) and the sciences of the mind (Cognitive Sciences). Advances on this kind of research provide a map of localization of cognitive functions in the human brain. Do these results help us to understand how mind relates to the brain? In my view, the results obtained by the Cognitive Neurosciences lead to new investigations in the domain of Molecular Neurobiology, aimed at discovering biophysical mechanisms that generate the activity measured by neuroimaging instruments. In this context, I argue that the understanding of how ionic/molecular processes support cognition and consciousness cannot be made by means of the standard reductionist explanations. Knowledge of ionic/molecular mechanisms can contribute to our understanding of the human mind as long as we assume an alternative form of explanation, based on psycho-physical similarities, together with an ontological view of mentality and spirituality as embedded in physical nature (and not outside nature, as frequently assumed in western culture). PMID:22058629

Investigation of secondary school, undergraduate, and graduate learners' mental models of ionic bonding

NASA Astrophysics Data System (ADS)

Coll, Richard K.; Treagust, David F.

2003-05-01

Secondary school, undergraduate, and graduate level learners' mental models of bonding in ionic substances were explored using an interview protocol that involved the use of physical substances and a focus card containing depictions of ionic bonding and structure. Teachers and faculty from the teaching institutions were interviewed to contextualize teaching models within the educational setting for the inquiry. These data resulted in two socially negotiated consensus teaching models and a series of criterial attributes for these models: the essential qualities, all of which must be negotiated, if the model is used in a way that is acceptable to scientists. The secondary school learners see ionic bonding as consisting of attraction of oppositely charged species that arise from the transfer of electrons driven by the desire of atoms to obtain an octet of electrons. The undergraduates see the lattice structure as a key component of ionic substances and quickly identified specific ionic lattices for the physical prompts used as probes. The graduates also identified strongly with ionic lattices, were less likely to focus on particular ionic structures, and had a stronger appreciation for the notion of the ionic-covalent continuum. The research findings suggest that learners at all educational levels harbor a number of alternative conceptions and prefer to use simple mental models. These findings suggest that teachers and university faculty need to provide stronger links between the detailed nature of a model and its intended purpose.

Investigation of CO2 capture mechanisms of liquid-like nanoparticle organic hybrid materials via structural characterization.

PubMed

Park, Youngjune; Decatur, John; Lin, Kun-Yi Andrew; Park, Ah-Hyung Alissa

2011-10-28

Nanoparticle organic hybrid materials (NOHMs) have been recently developed that comprise an oligomeric or polymeric canopy tethered to surface-modified nanoparticles via ionic or covalent bonds. It has already been shown that the tunable nature of the grafted polymeric canopy allows for enhanced CO(2) capture capacity and selectivity via the enthalpic intermolecular interactions between CO(2) and the task-specific functional groups, such as amines. Interestingly, for the same amount of CO(2) loading NOHMs have also exhibited significantly different swelling behavior compared to that of the corresponding polymers, indicating a potential structural effect during CO(2) capture. If the frustrated canopy species favor spontaneous ordering due to steric and/or entropic effects, the inorganic cores of NOHMs could be organized into unusual structural arrangements. Likewise, the introduction of small gaseous molecules such as CO(2) could reduce the free energy of the frustrated canopy. This entropic effect, the result of unique structural nature, could allow NOHMs to capture CO(2) more effectively. In order to isolate the entropic effect, NOHMs were synthesized without the task-specific functional groups. The relationship between their structural conformation and the underlying mechanisms for the CO(2) absorption behavior were investigated by employing NMR and ATR FT-IR spectroscopies. The results provide fundamental information needed for evaluating and developing novel liquid-like CO(2) capture materials and give useful insights for designing and synthesizing NOHMs for more effective CO(2) capture. This journal is © the Owner Societies 2011

High performance ultracapacitors with carbon nanomaterials and ionic liquids

DOEpatents

Lu, Wen; Henry, Kent Douglas

2012-10-09

The present invention is directed to the use of carbon nanotubes and/or electrolyte structures in various electrochemical devices, such as ultracapacitors having an ionic liquid electrolyte. The carbon nanotubes are preferably aligned carbon nanotubes. Compared to randomly entangled carbon nanotubes, aligned carbon nanotubes can have better defined pore structures and higher specific surface areas.

Communication: Anion-specific response of mesoscopic organization in ionic liquids upon pressurization

NASA Astrophysics Data System (ADS)

Lo Celso, Fabrizio; Triolo, Alessandro; Gontrani, Lorenzo; Russina, Olga

2018-06-01

One of the outstanding features of ionic liquids is their inherently hierarchical structural organization at mesoscopic spatial scales. Recently experimental and computational studies showed the fading of this feature when pressurising. Here we use simulations to show that this effect is not general: appropriate anion choice leads to an obstinate resistance against pressurization.

Organo-redox shuttle promoted protic ionic liquid electrolyte for supercapacitor

NASA Astrophysics Data System (ADS)

Sathyamoorthi, S.; Suryanarayanan, V.; Velayutham, D.

2015-01-01

Performance of activated charcoal based supercapacitor (SC) containing hydroquinone (HQ), as an organic redox shuttle, is evaluated in triethylammonium bis(trifluoromethane)sulfonimide (TEATFSI). Cyclic voltammograms of the SC show pseudocapacitive contribution of HQ and the galvanostatic charge-discharge measurement shows enhanced specific capacitance (72.0 F g-1) and specific energy (31.22 Wh Kg-1). The presence of HQ shows low charge transfer resistance, as confirmed by electrochemical impedance spectroscopy. Cyclic stability of the SC in the redox mediated electrolyte is comparable with that of the protic ionic liquid.

Electroactive Ionic Soft Actuators with Monolithically Integrated Gold Nanocomposite Electrodes.

PubMed

Yan, Yunsong; Santaniello, Tommaso; Bettini, Luca Giacomo; Minnai, Chloé; Bellacicca, Andrea; Porotti, Riccardo; Denti, Ilaria; Faraone, Gabriele; Merlini, Marco; Lenardi, Cristina; Milani, Paolo

2017-06-01

Electroactive ionic gel/metal nanocomposites are produced by implanting supersonically accelerated neutral gold nanoparticles into a novel chemically crosslinked ion conductive soft polymer. The ionic gel consists of chemically crosslinked poly(acrylic acid) and polyacrylonitrile networks, blended with halloysite nanoclays and imidazolium-based ionic liquid. The material exhibits mechanical properties similar to that of elastomers (Young's modulus ≈ 0.35 MPa) together with high ionic conductivity. The fabrication of thin (≈100 nm thick) nanostructured compliant electrodes by means of supersonic cluster beam implantation (SCBI) does not significantly alter the mechanical properties of the soft polymer and provides controlled electrical properties and large surface area for ions storage. SCBI is cost effective and suitable for the scaleup manufacturing of electroactive soft actuators. This study reports the high-strain electromechanical actuation performance of the novel ionic gel/metal nanocomposites in a low-voltage regime (from 0.1 to 5 V), with long-term stability up to 76 000 cycles with no electrode delamination or deterioration. The observed behavior is due to both the intrinsic features of the ionic gel (elasticity and ionic transport capability) and the electrical and morphological features of the electrodes, providing low specific resistance (<100 Ω cm -2 ), high electrochemical capacitance (≈mF g -1 ), and minimal mechanical stress at the polymer/metal composite interface upon deformation. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

β-cyclodextrin-ionic liquid polymer based dynamically coating for simultaneous determination of tetracyclines by capillary electrophoresis.

PubMed

Zhou, Chunyan; Deng, Jingjing; Shi, Guoyue; Zhou, Tianshu

2017-04-01

Tetracyclines are a group of broad spectrum antibiotics widely used in animal husbandry to prevent and treat diseases. However, the improper use of tetracyclines may result in the presence of their residues in animal tissues or waste. Recently, great attention has been drawn towards the green solvents ionic liquids. Ionic liquids have been employed as a coating material to modify the electroosmotic flow in capillary electrophoresis. In this study, a functionalized ionic liquid, mono-6-deoxy-6-(3-methylimidazolium)-β-cyclodextrin tosylate, was synthesized and used for the simultaneous separation and quantification of tetracyclines by capillary electrophoresis. Good separation efficiency could be achieved due to the multiple functions of β-cyclodextrin derived ionic liquid, including the electrostatic interaction, the hydrogen bonding, and the cavity structure in β-cyclodextrin ionic liquid which can entrap the tetracyclines to form inclusion complex. After optimization, baseline separation achieved in 25 min with the running buffer consisted of 10 mmol/L, pH 7.2 phosphate buffer and 20 mmol/L β-cyclodextrin ionic liquid. The satisfied result demonstrated that the β-cyclodextrin ionic liquid is an ideal background electrolyte modifier in the separation of tetracyclines with high stability and good reproducibility. And it is an effective strategy to design and synthesize specific ILs as additive applied in separation. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A computer program for geochemical analysis of acid-rain and other low-ionic-strength, acidic waters

USGS Publications Warehouse

Johnsson, P.A.; Lord, D.G.

1987-01-01

ARCHEM, a computer program written in FORTRAN 77, is designed primarily for use in the routine geochemical interpretation of low-ionic-strength, acidic waters. On the basis of chemical analyses of the water, and either laboratory or field determinations of pH, temperature, and dissolved oxygen, the program calculates the equilibrium distribution of major inorganic aqueous species and of inorganic aluminum complexes. The concentration of the organic anion is estimated from the dissolved organic concentration. Ionic ferrous iron is calculated from the dissolved oxygen concentration. Ionic balances and comparisons of computed with measured specific conductances are performed as checks on the analytical accuracy of chemical analyses. ARCHEM may be tailored easily to fit different sampling protocols, and may be run on multiple sample analyses. (Author 's abstract)

High-performance supercapacitors based on vertically aligned carbon nanotubes and nonaqueous electrolytes

NASA Astrophysics Data System (ADS)

Kim, Byungwoo; Chung, Haegeun; Kim, Woong

2012-04-01

We demonstrate the high performance of supercapacitors fabricated with vertically aligned carbon nanotubes and nonaqueous electrolytes such as ionic liquids and conventional organic electrolytes. Specific capacitance, maximum power and energy density of the supercapacitor measured in ionic liquid were ˜75 F g-1, ˜987 kW kg-1 and ˜27 W h kg-1, respectively. The high power performance was consistently indicated by a fast relaxation time constant of 0.2 s. In addition, electrochemical oxidation of the carbon nanotubes improved the specific capacitance (˜158 F g-1) and energy density (˜53 W h kg-1). Both high power and energy density could be attributed to the fast ion transport realized by the alignment of carbon nanotubes and the wide operational voltage defined by the ionic liquid. The demonstrated carbon-nanotube- and nonaqueous-electrolyte-based supercapacitors show great potential for the development of high-performance energy storage devices.

High-performance supercapacitors based on vertically aligned carbon nanotubes and nonaqueous electrolytes.

PubMed

Kim, Byungwoo; Chung, Haegeun; Kim, Woong

2012-04-20

We demonstrate the high performance of supercapacitors fabricated with vertically aligned carbon nanotubes and nonaqueous electrolytes such as ionic liquids and conventional organic electrolytes. Specific capacitance, maximum power and energy density of the supercapacitor measured in ionic liquid were ~75 F g(-1), ~987 kW kg(-1) and ~27 W h kg(-1), respectively. The high power performance was consistently indicated by a fast relaxation time constant of 0.2 s. In addition, electrochemical oxidation of the carbon nanotubes improved the specific capacitance (~158 F g(-1)) and energy density (~53 W h kg(-1)). Both high power and energy density could be attributed to the fast ion transport realized by the alignment of carbon nanotubes and the wide operational voltage defined by the ionic liquid. The demonstrated carbon-nanotube- and nonaqueous-electrolyte-based supercapacitors show great potential for the development of high-performance energy storage devices. © 2012 IOP Publishing Ltd

Study of Stable Cathodes and Electrolytes for High Specific Density Lithium-Air Battery

NASA Technical Reports Server (NTRS)

Hernandez-Lugo, Dionne M.; Wu, James; Bennett, William; Ming, Yu; Zhu, Yu

2015-01-01

Future NASA missions require high specific energy battery technologies, greater than 400 Wh/kg. Current NASA missions are using "state-of-the-art" (SOA) Li-ion batteries (LIB), which consist of a metal oxide cathode, a graphite anode and an organic electrolyte. NASA Glenn Research Center is currently studying the physical and electrochemical properties of the anode-electrolyte interface for ionic liquid based Li-air batteries. The voltage-time profiles for Pyr13FSI and Pyr14TFSI ionic liquids electrolytes studies on symmetric cells show low over-potentials and no dendritic lithium morphology. Cyclic voltammetry measurements indicate that these ionic liquids have a wide electrochemical window. As a continuation of this work, sp2 carbon cathode and these low flammability electrolytes were paired and the physical and electrochemical properties were studied in a Li-air battery system under an oxygen environment.

Ultraflexible and tailorable all-solid-state supercapacitors using polyacrylamide-based hydrogel electrolyte with high ionic conductivity.

PubMed

Li, Huili; Lv, Tian; Li, Ning; Yao, Yao; Liu, Kai; Chen, Tao

2017-11-30

Hydrogels with high ionic conductivity consisting of a cross-linked polymer network swollen in water are very promising to be used as an electrolyte for all-solid-state supercapacitors. However, there are rather few flexible supercapacitors using ionic conducting hydrogel electrolytes reported to date. In this work, highly flexible and ionic conducting polyacrylamide hydrogels were synthesized through a simple approach. On using the ionic hydrogels as the electrolyte, the resulting supercapacitors not only exhibited a high specific capacitance but also showed a long self-discharge time (over 10 hours to the half of original open-circuit voltage) and a low leakage current. These newly-developed all-solid-state supercapacitors can be bent, knot, and kneaded for 5000 cycles without performance decay, suggesting excellent flexibility and mechanical stability. These all-solid-state supercapacitors can also be easily tailored into strip-like supercapacitors without a short circuit, which provides an efficient approach to fabricate wearable energy storage devices.

Crosslinked Polymer Ionic Liquid/Ionic Liquid Blends Prepared by Photopolymerization as Solid-State Electrolytes in Supercapacitors.

PubMed

Wang, Po-Hsin; Wang, Tzong-Liu; Lin, Wen-Churng; Lin, Hung-Yin; Lee, Mei-Hwa; Yang, Chien-Hsin

2018-04-07

A photopolymerization method is used to prepare a mixture of polymer ionic liquid (PIL) and ionic liquid (IL). This mixture is used as a solid-state electrolyte in carbon nanoparticle (CNP)-based symmetric supercapacitors. The solid electrolyte is a binary mixture of a PIL and its corresponding IL. The PIL matrix is a cross-linked polyelectrolyte with an imidazole salt cation coupled with two anions of Br - in PIL-M-(Br) and TFSI - in PIL-M-(TFSI), respectively. The corresponding ionic liquids have imidazolium salt cation coupled with two anions of Br - and TFSI - , respectively. This study investigates the electrochemical characteristics of PILs and their corresponding IL mixtures used as a solid electrolyte in supercapacitors. Results show that a specific capacitance, maximum power density and energy density of 87 and 58 F·g - ¹, 40 and 48 kW·kg - ¹, and 107 and 59.9 Wh·kg - ¹ were achieved in supercapacitors based on (PIL-M-(Br)) and (PIL-M-(TFSI)) solid electrolytes, respectively.

[Verification of a decrease in the rigidity of the phage lambda DNA polymeric chain in low ionic strength aqueous solutions by testing the polymer-polymer interlink interactions].

PubMed

Arutiunian, A V; Ivanova, M A; Kurliand, D I; Kapshin, Iu S; Landa, S B; Poshekhonov, S T; Drobchenko, E A; Shevelev, I V

2011-01-01

Changes in the rigidity of the polymetric chain of phage lambda double-strand DNA have been studied by laser correlation spectroscopy. It was shown that, as the ionic strength increases, the effect of the screening of the hydrodynamic interaction of the links of the polymeric chain specific for polymeric coils arises in a DNA solution. It is assumed that the screening occurs when the threshold of the overlapping of DNA coils is achieved. The overlapping of coils is the result of a previously observed significant rise of DNA coil size from abnormally small DNA coils in low ionic strength buffers (about 10(-2) M Na+ or less) to maximum possible large coils in the 5SSC and 5SSC-like buffers. Further analysis of the far interlink interactions in linear lambda phage DNA coils in similar buffers at pH 7 and 4 confirms the earlier proposal about the role of H+ ions in the appearance of abnormally small DNA coils. The abnormal decrease in the DNA coil size in low ionic strength buffers is not a specific feature of lambda phage DNA only.

Nanoscale organization in the fluorinated room temperature ionic liquid: Tetraethyl ammonium (trifluoromethanesulfonyl)(nonafluorobutylsulfonyl)imide

NASA Astrophysics Data System (ADS)

Lo Celso, F.; Appetecchi, G. B.; Jafta, C. J.; Gontrani, L.; Canongia Lopes, J. N.; Triolo, A.; Russina, O.

2018-05-01

Fluorinated Room Temperature Ionic Liquids (FRTILs) are a branch of ionic liquids that is the object of growing interest for a wide range of potential applications, due to the synergic combination of specifically ionic features and those properties that stem from fluorous tails. So far limited experimental work exists on the micro- and mesoscopic structural organization in this class of compounds. Such a work is however necessary to fully understand morphological details at atomistic level that would have strong implications in terms of bulk properties. Here we use the synergy between X-ray and neutron scattering together with molecular dynamics simulations to access structural details of a technologically relevant FRTIL that is characterised by an anion bearing a long enough fluorinated tail to develop specific morphological features. In particular, we find the first experimental evidence that in FRTILs bearing an asymmetric bis(perfluoroalkyl)sulfonyl-imide anion, fluorous side chains tend to be spatially segregated into nm-scale spatial heterogeneities. This feature together with the well-established micro-segregation of side alkyl chains in conventional RTILs leads to the concept of triphilic ILs, whose technological applications are yet to be fully developed.

Understanding the effect models of ionic liquids in the synthesis of NH4-Dw and γ-AlOOH nanostructures and their conversion into porous γ-Al2O3.

PubMed

Duan, Xiaochuan; Kim, Tongil; Li, Di; Ma, Jianmin; Zheng, Wenjun

2013-05-03

Well-dispersed ammonium aluminum carbonate hydroxide (NH4-Dw) and γ-AlOOH nanostructures with controlled morphologies have been synthesized by employing an ionic-liquid-assisted hydrothermal process. The basic strategies that were used in this work were: 1) A controllable phase transition from NH4-Dw to γ-AlOOH could be realized by increasing the reaction temperature and 2) the morphological evolution of NH4-Dw and γ-AlOOH nanostructures could be influenced by the concentration of the ionic liquid. Based on these experimental results, the main objective of this work was to clarify the effect models of the ionic liquids on the synthesis of NH4-Dw and γ-AlOOH nanostructures, which could be divided into cationic- or anionic-dominant effect models, as determined by the different surface structures of the targets. Specifically, under the cationic-dominant regime, the ionic liquids mainly showed dispersion effects for the NH4-Dw nanostructures, whereas the anionic-dominant model could induce the self-assembly of the γ-AlOOH particles to form hierarchical structures. Under the guidance of the proposed models, the effect of the ionic liquids would be optimized by an appropriate choice of cations or anions, as well as by considering the different effect models with the substrate surface. We expect that such effect models between ionic liquids and the target products will be helpful for understanding and designing rational ionic liquids that contain specific functional groups, thus open up new opportunities for the synthesis of inorganic nanomaterials with new morphologies and improved properties. In addition, these as-prepared NH4-Dw and γ-AlOOH nanostructures were converted into porous γ-Al2O3 nanostructures by thermal decomposition, whilst preserving the same morphology. By using HRTEM and nitrogen-adsorption analysis, the obtained γ-Al2O3 samples were found to have excellent porous properties and, hence, may have applications in catalysis and adsorption. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Protein Crystallization Using Room Temperature Ionic Fluids

NASA Technical Reports Server (NTRS)

Pusey, Marc L.; Paley, Mark Steve; Turner, Megan B.; Rogers, Robin D.

2006-01-01

The ionic liquids (ILs) 1-butyl-3-methylimidizolium chloride (C4mim-C1), 1-butyl-3- methylimidizolium diethyleneglycol monomethylethersulfate ([C4mim]DEMGS), and 1-butyl-1 -methylpyrollidinium dihydrogenphosphate ([p1,4]dhp) were tested for their effects on the crystallization of the proteins canavalin, beta-lactoglobulin B, xylanase, and glucose isomerase, using a standard high throughput screen. The crystallization experiments were set up with the ILs added to the protein solutions at 0.2 and 0.4 M final concentrations. Crystallization droplets were set up at three proteixprecipitant ratios (1:1, 2:1, and 4:l), which served to progressively dilute the effects of the screen components while increasing the equilibrium protein and IL concentrations. Crystals were obtained for all four proteins at a number of conditions where they were not obtained from the IL-free control experiment. Over half of the protein-IL combinations tested had more successful outcomes than negative, where the IL-free crystallization was better than the corresponding IL-containing outcome, relative to the control. One of the most common causes of a negative outcome was solubilization of the protein by the IL, resulting in a clear drop. In one instance, we were able to use the IL-induced solubilizing to obtain beta-lactoglobulin B crystals from conditions that gave precipitated protein in the absence of IL. The results suggest that it may be feasible to develop ILs specifically for the task of macromolecule crystallization.

Hydroxyl-Exchanged Nanoporous Ionic Copolymer toward Low-Temperature Cycloaddition of Atmospheric Carbon Dioxide into Carbonates.

PubMed

Guo, Zengjing; Cai, Xiaochun; Xie, Jingyan; Wang, Xiaochen; Zhou, Yu; Wang, Jun

2016-05-25

An ionic copolymer catalyst with nanopores, large surface area, high ionic density, and superior basicity was prepared via the radical copolymerization of amino-functionalized ionic liquid bromide and divinylbenzene, followed with a hydroxyl exchange for removing bromonium. Evaluated in chemical fixation of CO2 with epoxides into cyclic carbonates in the absence of any solvent and basic additive, the nanoporous copolymer catalyst showed high and stable activity, superior to various control catalysts including the halogen-containing analogue. Further, high yields were obtained over a wide scope of substrates including aliphatic long carbon-chain alkyl epoxides and internal epoxide, even under atmospheric pressure and less than 100 °C for the majority of the substrates. On the basis of in situ Fourier transform infrared (FT-IR) investigation and density functional theory (DFT) calculation for the reaction intermediates, we proposed a possible reaction mechanism accounting for the superior catalytic activity of the ionic copolymer. The specifically prepared ionic copolymer material of this work features highly stable, noncorrosive, and sustainable catalysis and, thus, may be a new possibility for efficient chemical fixation of CO2 since it is an environmentally friendly, metal-free solid catalyst.

SN2 fluorination reactions in ionic liquids: a mechanistic study towards solvent engineering.

PubMed

Oh, Young-Ho; Jang, Hyeong Bin; Im, Suk; Song, Myoung Jong; Kim, So-Yeon; Park, Sung-Woo; Chi, Dae Yoon; Song, Choong Eui; Lee, Sungyul

2011-01-21

In the catalysis of S(N)2 fluorination reactions, the ionic liquid anion plays a key role as a Lewis base by binding to the counterion Cs(+) and thereby reducing the retarding Coulombic influence of Cs(+) on the nucleophile F(-). The reaction rates also depend critically on the structures of ionic liquid cation, for example, n-butyl imidazolium gives no S(N)2 products, whereas n-butylmethyl imidazolium works well. The origin of the observed phenomenal synergetic effects by the ionic liquid [mim-(t)OH][OMs], in which t-butanol is bonded covalently to the cation [mim], is that the t-butanol moiety binds to the leaving group of the substrate, moderating the retarding interactions between the acidic hydrogen and F(-). This work is a significant step toward designing and engineering solvents for promoting specific chemical reactions.

Expression of a Deschampsia antarctica Desv. Polypeptide with Lipase Activity in a Pichia pastoris Vector

PubMed Central

Rabert, Claudia; Gutiérrez-Moraga, Ana; Navarrete-Gallegos, Alejandro; Navarrete-Campos, Darío; Bravo, León A.; Gidekel, Manuel

2014-01-01

The current study isolated and characterized the Lip3F9 polypeptide sequence of Deschampsia antarctica Desv. (GeneBank Accession Number JX846628), which was found to be comprised of 291 base pairs and was, moreover, expressed in Pichia pastoris X-33 cells. The enzyme was secreted after 24 h of P. pastoris culture incubation and through induction with methanol. The expressed protein showed maximum lipase activity (35 U/L) with an optimal temperature of 37 °C. The lipase-expressed enzyme lost 50% of its specific activity at 25 °C, a behavior characteristic of a psychrotolerant enzyme. Recombinant enzyme activity was measured in the presence of ionic and non-ionic detergents, and a decrease in enzyme activity was detected for all concentrations of ionic and non-ionic detergents assessed. PMID:24514564

Quantifying the effect of ionic screening with protein-decorated graphene transistors

PubMed Central

Ping, Jinglei; Xi, Jin; Saven, Jeffery G.; Liu, Renyu; Charlie Johnson, A. T.

2015-01-01

Liquid-based applications of biomolecule-decorated field-effect transistors (FETs) range from biosensors to in vivo implants. A critical scientific challenge is to develop a quantitative understanding of the gating effect of charged biomolecules in ionic solution and how this influences the readout of the FETs. To address this issue, we fabricated protein-decorated graphene FETs and measured their electrical properties, specifically the shift in Dirac voltage, in solutions of varying ionic strength. We found excellent quantitative agreement with a model that accounts for both the graphene polarization charge and ionic screening of ions adsorbed on the graphene as well as charged amino acids associated with the immobilized protein. The technique and analysis presented here directly couple the charging status of bound biomolecules to readout of liquid-phase FETs fabricated with graphene or other two-dimensional materials. PMID:26626969

Results Of Hg Speciation Testing On DWPF SMECT-1, SMECT-3, And SMECT-5 Samples

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

Bannochie, C.

2016-01-07

The Savannah River National Laboratory (SRNL) was tasked with preparing and shipping samples for Hg speciation by Eurofins Frontier Global Sciences, Inc. in Seattle, WA on behalf of the Savannah River Remediation (SRR) Mercury Task Team. The thirteenth shipment of samples was designated to include Defense Waste Processing Facility (DWPF) Slurry Mix Evaporator Condensate Tank (SMECT) from Sludge Receipt and Adjustment Tank (SRAT) Batch 736 and 738 samples. Triplicate samples of each material were prepared for this shipment. Each replicate was analyzed for seven Hg species: total Hg, total soluble (dissolved) Hg, elemental Hg [Hg(0)], ionic (inorganic) Hg [Hg(I) andmore » Hg(II)], methyl Hg [CH 3Hg-X, where X is a counter anion], ethyl Hg [CH 3CH 2-Hg-X, where X is a counter anion], and dimethyl Hg [(CH 3) 2Hg]. The difference between the total Hg and total soluble Hg measurements gives the particulate Hg concentration, i.e. Hg adsorbed to the surface of particulate matter in the sample but without resolution of the specific adsorbed species. The average concentrations of Hg species in the aqueous samples derived from Eurofins reported data corrected for dilutions performed by SRNL are tabulated.« less

Cold chemistry with ionic partners: quantum features of HeH+(1Σ) with H(1S) at ultralow energies.

PubMed

Bovino, S; Tacconi, M; Gianturco, F A

2011-07-28

Quantum reactive calculations are presented for an ion-atom reaction involving the HeH(+)cation and its destruction via a barrierless interaction with H atoms. The range of collision energies considered is that of a cold trap regime (around and below millikelvin) where the ionic partner could be spatially confined. Specific resonant features caused by the interplay of the strong ionic interaction with the very slow partners' dynamics are found and analyzed. Indications are also given on the consequences of the abstraction mechanism that acts for this reaction at low energies. © 2011 American Chemical Society

ORNL-GM: Development of Ionic Liquid-Additized, GF-5/6 Compatible Low-Viscosity Oils for Automotive Engine and Rear Axle Lubrication for 4% Improved Fuel Economy

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

Qu, Jun; Zhou, Yan; Luo, Huimin

The overall objective of this project are as follows: Further develop ionic liquid (IL)-additized lowviscosity engine oils meeting the GF-5/6 specifications and possessing superior lubricating characteristics; Expand the IL additive technology to rear axle lubricants; and Seek a combined improvement in the vehicle fuel economy

Understanding the effect of side groups in ionic liquids on carbon-capture properties: a combined experimental and theoretical effort

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

Yan, Fangyong; Lartey, Michael; Damodaran, Krishnan

2013-01-01

Ionic liquids are an emerging class of materials with applications in a variety of fields. Steady progress has been made in the creation of ionic liquids tailored to specific applications. However, the understanding of the underlying structure–property relationships has been slower to develop. As a step in the effort to alleviate this deficiency, the influence of side groups on ionic liquid properties has been studied through an integrated approach utilizing synthesis, experimental determination of properties, and simulation techniques. To achieve this goal, a classical force field in the framework of OPLS/Amber force fields has been developed to predict ionic liquidmore » properties accurately. Cu(I)-catalyzed click chemistry was employed to synthesize triazolium-based ionic liquids with diverse side groups. Values of densities were predicted within 3% of experimental values, whereas self-diffusion coefficients were underestimated by about an order of magnitude though the trends were in excellent agreement, the activation energy calculated in simulation correlates well with experimental values. The predicted Henry coefficient for CO{sub 2} solubility reproduced the experimentally observed trends. This study highlights the importance of integrating experimental and computational approaches in property prediction and materials development, which is not only useful in the development of ionic liquids for CO{sub 2} capture but has application in many technological fields.« less

Understanding the effect of side groups in ionic liquids on carbon-capture properties: a combined experimental and theoretical effort

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

Yan, Fangyong; Lartey, Michael; Damodaran, Krishnan

Ionic liquids are an emerging class of materials with applications in a variety of fields. Steady progress has been made in the creation of ionic liquids tailored to specific applications. However, the understanding of the underlying structure–property relationships has been slower to develop. As a step in the effort to alleviate this deficiency, the influence of side groups on ionic liquid properties has been studied through an integrated approach utilizing synthesis, experimental determination of properties, and simulation techniques. To achieve this goal, a classical force field in the framework of OPLS/Amber force fields has been developed to predict ionic liquidmore » properties accurately. Cu(I)-catalyzed click chemistry was employed to synthesize triazolium-based ionic liquids with diverse side groups. Values of densities were predicted within 3% of experimental values, whereas self-diffusion coefficients were underestimated by about an order of magnitude though the trends were in excellent agreement, the activation energy calculated in simulation correlates well with experimental values. The predicted Henry coefficient for CO{sub 2} solubility reproduced the experimentally observed trends. This study highlights the importance of integrating experimental and computational approaches in property prediction and materials development, which is not only useful in the development of ionic liquids for CO{sub 2} capture but has application in many technological fields.« less

Ionic Conductivity and Air Stability of Al-Doped Li₇La₃Zr₂O₁₂ Sintered in Alumina and Pt Crucibles.

PubMed

Xia, Wenhao; Xu, Biyi; Duan, Huanan; Guo, Yiping; Kang, Hongmei; Li, Hua; Liu, Hezhou

2016-03-02

Li7La3Zr2O12 (LLZO) is a promising electrolyte material for all-solid-state battery due to its high ionic conductivity and good stability with metallic lithium. In this article, we studied the effect of crucibles on the ionic conductivity and air stability by synthesizing 0.25Al doped LLZO pellets in Pt crucibles and alumina crucibles, respectively. The results show that the composition and microstructure of the pellets play important roles influencing the ionic conductivity, relative density, and air stability. Specifically, the 0.25Al-LLZO pellets sintered in Pt crucibles exhibit a high relative density (∼96%) and high ionic conductivity (4.48 × 10(-4) S cm(-1)). The ionic conductivity maintains 3.6 × 10(-4) S cm(-1) after 3-month air exposure. In contrast, the ionic conductivity of the pellets from alumina crucibles is about 1.81 × 10(-4) S cm(-1) and drops to 2.39 × 10(-5) S cm(-1) 3 months later. The large grains and the reduced grain boundaries in the pellets sintered in Pt crucibles are favorable to obtain high ionic conductivity and good air stability. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy results suggest that the formation of Li2CO3 on the pellet surface is probably another main reason, which is also closely related to the relative density and the amount of grain boundary within the pellets. This work stresses the importance of synthesis parameters, crucibles included, to obtain the LLZO electrolyte with high ionic conductivity and good air stability.

Self-Healing Behavior of Ethylene-Based Ionomers

NASA Technical Reports Server (NTRS)

Kalista, Stephen J., Jr.; Ward, Thomas C.; Oyetunji, Zainab

2004-01-01

The self-healing behavior of poly(ethylene-co-methacrylic acid) (EMAA)-based ionomers holds tremendous potential for use in a wide variety of unique applications. However, to effectively utilize this self-healing behavior and to design novel materials which possess this ability, the mechanism by which they heal must first be understood ionomers are a class of polymers that can be described as copolymers containing less than 15 mol% ionic content whereby the bulk properties are governed by ionic interactions within the polymer. These ionic groups aggregate into discrete regions known as multiplets which overlap forming clusters that act as physical cross-links profoundly influencing the bulk physical properties. These clusters possess an order-disorder transition (T(sub i)) where the clustered regions may rearrange themselves given time and stimuli. Recognizing the strong influence of these ionic regions on other well understood ionomer properties, their role in self-heating behavior will be assessed. The self-healing behavior is observed following projectile puncture. It has been suggested that during impact energy is passed to the ionomer material, heating it to the melt state. After penetration, it is proposed that the ionic regions maintain their attractions and flow together patching the hole. Thus, the importance of this ionic character and is unique interaction must be established. This will be accomplished through examination of materials with varying ionic content and through the analysis of the T(sub i). The specific ionomer systems examined include a number of ethylene-based materials. Materials of varying ionic content, including the non-ionic base copolymers, will be examined by peel tests, projectile impact and DSC analysis. The information will also be compared with some basic data on LDPE material.

Non-ionic detergents facilitate non-specific binding of M13 bacteriophage to polystyrene surfaces.

PubMed

Hakami, Abdulrahim R; Ball, Jonathan K; Tarr, Alexander W

2015-09-01

Phage-displayed random peptide libraries are widely used for identifying peptide interactions with proteins and other substrates. Selection of peptide ligands involves iterative rounds of affinity enrichment. The binding properties of the selected phage clones are routinely tested using immunoassay after propagation to high titre in a bacterial host and precipitation using polyethylene glycol (PEG) and high salt concentration. These immunoassays can suffer from low sensitivity and high background signals. Polysorbate 20 (Tween(®) 20) is a non-ionic detergent commonly used in immunoassay washing buffers to reduce non-specific binding, and is also used as a blocking reagent. We have observed that Tween 20 enhances non-specific M13 library phage binding in a peptide-independent manner. Other non-ionic detergents were also found to promote significant, dose-dependent non-specific phage binding in ELISA. This effect was not observed for assays using phage concentrated by ultracentrifugation, suggesting that interactions occur between detergents and the PEG-precipitated phage, irrespective of the displayed peptide motif. This artefact may impact on successful affinity selection of peptides from phage-display libraries. We propose alternative methods for screening phage libraries for identifying binding interactions with target ligands. Copyright © 2015 Elsevier B.V. All rights reserved.

Chromatographic and spectroscopic methods for the determination of solvent properties of room temperature ionic liquids.

PubMed

Poole, Colin F

2004-05-28

Room temperature ionic liquids are novel solvents with favorable environmental and technical features. Synthetic routes to over 200 room temperature ionic liquids are known but for most ionic liquids physicochemical data are generally lacking or incomplete. Chromatographic and spectroscopic methods afford suitable tools for the study of solvation properties under conditions that approximate infinite dilution. Gas-liquid chromatography is suitable for the determination of gas-liquid partition coefficients and activity coefficients as well as thermodynamic constants derived from either of these parameters and their variation with temperature. The solvation parameter model can be used to define the contribution from individual intermolecular interactions to the gas-liquid partition coefficient. Application of chemometric procedures to a large database of system constants for ionic liquids indicates their unique solvent properties: low cohesion for ionic liquids with weakly associated ions compared with non-ionic liquids of similar polarity; greater hydrogen-bond basicity than typical polar non-ionic solvents; and a range of dipolarity/polarizability that encompasses the same range as occupied by the most polar non-ionic liquids. These properties can be crudely related to ion structures but further work is required to develop a comprehensive approach for the design of ionic liquids for specific applications. Data for liquid-liquid partition coefficients is scarce by comparison with gas-liquid partition coefficients. Preliminary studies indicate the possibility of using the solvation parameter model for interpretation of liquid-liquid partition coefficients determined by shake-flask procedures as well as the feasibility of using liquid-liquid chromatography for the convenient and rapid determination of liquid-liquid partition coefficients. Spectroscopic measurements of solvatochromic and fluorescent probe molecules in room temperature ionic liquids provide insights into solvent intermolecular interactions although interpretation of the different and generally uncorrelated "polarity" scales is sometimes ambiguous. All evidence points to the ionic liquids as a unique class of polar solvents suitable for technical development. In terms of designer solvents, however, further work is needed to fill the gaps in our knowledge of the relationship between ion structures and physicochemical properties.

Spectrum of antimicrobial activity associated with ionic colloidal silver.

PubMed

Morrill, Kira; May, Kathleen; Leek, Daniel; Langland, Nicole; Jeane, La Deana; Ventura, Jose; Skubisz, Corey; Scherer, Sean; Lopez, Eric; Crocker, Ephraim; Peters, Rachel; Oertle, John; Nguyen, Krystine; Just, Scott; Orian, Michael; Humphrey, Meaghan; Payne, David; Jacobs, Bertram; Waters, Robert; Langland, Jeffrey

2013-03-01

Silver has historically and extensively been used as a broad-spectrum antimicrobial agent. However, the Food and Drug Administration currently does not recognize colloidal silver as a safe and effective antimicrobial agent. The goal of this study was to further evaluate the antimicrobial efficacy of colloidal silver. Several strains of bacteria, fungi, and viruses were grown under multicycle growth conditions in the presence or absence of ionic colloidal silver in order to assess the antimicrobial activity. For bacteria grown under aerobic or anaerobic conditions, significant growth inhibition was observed, although multiple treatments were typically required. For fungal cultures, the effects of ionic colloidal silver varied significantly between different genera. No viral growth inhibition was observed with any strains tested. The study data support ionic colloidal silver as a broad-spectrum antimicrobial agent against aerobic and anaerobic bacteria, while having a more limited and specific spectrum of activity against fungi.

The synthesis and the chemical and physical properties of non-aqueous silylamine solvents for carbon dioxide capture.

PubMed

Rohan, Amy L; Switzer, Jackson R; Flack, Kyle M; Hart, Ryan J; Sivaswamy, Swetha; Biddinger, Elizabeth J; Talreja, Manish; Verma, Manjusha; Faltermeier, Sean; Nielsen, Paul T; Pollet, Pamela; Schuette, George F; Eckert, Charles A; Liotta, Charles L

2012-11-01

Silylamine reversible ionic liquids were designed to achieve specific physical properties in order to address effective CO₂ capture. The reversible ionic liquid systems reported herein represent a class of switchable solvents where a relatively non-polar silylamine (molecular liquid) is reversibly transformed to a reversible ionic liquid (RevIL) by reaction with CO₂ (chemisorption). The RevILs can further capture additional CO₂ through physical absorption (physisorption). The effects of changes in structure on (1) the CO₂ capture capacity (chemisorption and physisorption), (2) the viscosity of the solvent systems at partial and total conversion to the ionic liquid state, (3) the energy required for reversing the CO₂ capture process, and (4) the ability to recycle the solvents systems are reported. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Effect of Lengthening Cation Ether Tails on Ionic Liquid Properties

DOE PAGES

Lall-Ramnarine, S.; Rodriguez, C.; Fernandez, R.; ...

2016-08-30

In order to explore the effect of multiple ether functionalities on ionic liquid properties, a series of ten pyrrolidinium ionic liquids and ten imidazolium ionic liquids bearing ether and alkyl side chains of varying lengths (4 to 10 atoms in length) were prepared for this study. Their physical properties, such as viscosity, conductivity and thermal profile were measured and compared. Consistent with earlier literature, a single ether substituent substantially decreases the viscosity of pyrrolidinium and imidazolium ILs compared to their alkyl congeners. Remarkably, as the number of ether units in the pyrrolidinium ILs increases there is hardly any increase inmore » the viscosity, in contrast to alkylpyrrolidinium ILs where the viscosity increases steadily with chain length. Viscosities of imidazolium ether ILs increase with chain length but always remain well below their alkyl congeners. These results provide significant insight on the choice of starting materials for researchers designing ILs for specific applications.« less

Preliminary Evidence of Reduced Brain Network Activation in Patients with Post-traumatic Migraine following Concussion

PubMed Central

Kontos, Anthony P.; Reches, Amit; Elbin, R. J.; Dickman, Dalia; Laufer, Ilan; Geva, Amir; Shacham, Galit; DeWolf, Ryan; Collins, Michael W.

2015-01-01

Post-traumatic migraine (PTM) (i.e., headache, nausea, light and/or noise sensitivity) is an emerging risk factor for prolonged recovery following concussion. Concussions and migraine share similar pathophysiology characterized by specific ionic imbalances in the brain. Given these similarities, patients with PTM following concussion may exhibit distinct electrophysiological patterns, although researchers have yet to examine the electrophysiological brain activation in patients with PTM following concussion. A novel approach that may help differentiate brain activation in patients with and without PTM is brain network activation (BNA) analysis. BNA involves an algorithmic analysis applied to multichannel EEG-ERP data that provides a network map of cortical activity and quantitative data during specific tasks. A prospective, repeated measures design was used to evaluate BNA (during Go/NoGo task), EEG-ERP, cognitive performance, and concussion related symptoms at 1, 2, 3, and 4-week post-injury intervals among athletes with a medically diagnosed concussion with PTM (n = 15) and without (NO-PTM) (n = 22); and age, sex, and concussion history matched controls without concussion (CONTROL) (n = 20). Participants with PTM had significantly reduced BNA compared to NO-PTM and CONTROLS for Go and NoGo components at 3 weeks and for NoGo component at 4 weeks post-injury. The PTM group also demonstrated a more prominent deviation of network activity compared to the other two groups over a longer period of time. The composite BNA algorithm may be a more sensitive measure of electrophysiological change in the brain that can augment established cognitive assessment tools for detecting impairment in individuals with PTM. PMID:26091725

Synergistic Effects of Mixing Sulfone and Ionic Liquid as Safe Electrolytes for Lithium Sulfur Batteries

DOE PAGES

Liao, Chen; Guo, Bingkun; Sun, Xiao-Guang; ...

2014-11-26

A strategy of mixing both an ionic liquid and sulfone is reported to give synergistic effects of reducing viscosity, increasing ionic conductivity, reducing polysulfide dissolution, and improving safety. The mixtures of ionic liquids and sulfones also show distinctly different physicochemical properties, including thermal properties and crystallization behavior. By using these electrolytes, lithium sulfur batteries assembled with lithium and mesoporous carbon composites show a reversible specific capacity of 1265 mAhg- 1 (second cycle) by using 40% 1.0 M lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) in N-methyl-Npropylpyrrolidinium bis(trifluoromethylsulfonyl)imide with 60% 1.0 M LiTFSI in methylisopropylsulfone in the first cycle. This capacity is slightly lower thanmore » that obtained in pure 1.0 M LiTFSI as the sulfone electrolyte; however, it exhibits excellent cycling stability and remains as high as 655 mAhg 1 even after 50 cycles. This strategy provides a method to alleviate polysulfide dissolution and redox shuttle phenomena, at the same time, with improved ionic conductivity.« less

A Spectral-SAR Model for the Anionic-Cationic Interaction in Ionic Liquids: Application to Vibrio fischeri Ecotoxicity

PubMed Central

Lacrămă, Ana-Maria; Putz, Mihai V.; Ostafe, Vasile

2007-01-01

Within the recently launched the spectral-structure activity relationship (S-SAR) analysis, the vectorial anionic-cationic model of a generic ionic liquid is proposed, along with the associated algebraic correlation factor in terms of the measured and predicted activity norms. The reliability of the present scheme is tested by assessing the Hansch factors, i.e. lipophylicity, polarizability and total energy, to predict the ecotoxicity endpoints of wide types of ionic liquids with ammonium, pyridinium, phosphonium, choline and imidazolium cations on the aquatic bacteria Vibrio fischeri. The results, while confirming the cationic dominant influence when only lipophylicity is considered, demonstrate that the anionic effect dominates all other more specific interactions. It was also proved that the S-SAR vectorial model predicts considerably higher activity for the ionic liquids than for its anionic and cationic subsystems separately, in all considered cases. Moreover, through applying the least norm-correlation path principle, the complete toxicological hierarchies are presented, unfolding the ecological rules of combined cationic and anionic influences in ionic liquid toxicity.

Crosslinked Polymer Ionic Liquid/Ionic Liquid Blends Prepared by Photopolymerization as Solid-State Electrolytes in Supercapacitors

PubMed Central

Wang, Po-Hsin; Wang, Tzong-Liu; Lin, Wen-Churng; Lin, Hung-Yin; Lee, Mei-Hwa; Yang, Chien-Hsin

2018-01-01

A photopolymerization method is used to prepare a mixture of polymer ionic liquid (PIL) and ionic liquid (IL). This mixture is used as a solid-state electrolyte in carbon nanoparticle (CNP)-based symmetric supercapacitors. The solid electrolyte is a binary mixture of a PIL and its corresponding IL. The PIL matrix is a cross-linked polyelectrolyte with an imidazole salt cation coupled with two anions of Br− in PIL-M-(Br) and TFSI− in PIL-M-(TFSI), respectively. The corresponding ionic liquids have imidazolium salt cation coupled with two anions of Br− and TFSI−, respectively. This study investigates the electrochemical characteristics of PILs and their corresponding IL mixtures used as a solid electrolyte in supercapacitors. Results show that a specific capacitance, maximum power density and energy density of 87 and 58 F·g−1, 40 and 48 kW·kg−1, and 107 and 59.9 Wh·kg−1 were achieved in supercapacitors based on (PIL-M-(Br)) and (PIL-M-(TFSI)) solid electrolytes, respectively. PMID:29642456

Rapid analysis of ultraviolet filters using dispersive liquid-liquid microextraction coupled to headspace gas chromatography and mass spectrometry.

PubMed

Pierson, Stephen A; Trujillo-Rodríguez, María J; Anderson, Jared L

2018-05-29

An ionic-liquid-based in situ dispersive liquid-liquid microextraction method coupled to headspace gas chromatography and mass spectrometry was developed for the rapid analysis of ultraviolet filters. The chemical structures of five ionic liquids were specifically designed to incorporate various functional groups for the favorable extraction of the target analytes. Extraction parameters including ionic liquid mass, molar ratio of ionic liquid to metathesis reagent, vortex time, ionic strength, pH, and total sample volume were studied and optimized. The effect of the headspace temperature and volume during the headspace sampling step was also evaluated to increase the sensitivity of the method. The optimized procedure is fast as it only required ∼7-10 min per extraction and allowed for multiple extractions to be performed simultaneously. In addition, the method exhibited high precision, good linearity, and low limits of detection for six ultraviolet filters in aqueous samples. The developed method was applied to both pool and lake water samples attaining acceptable relative recovery values. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Investigation of the electrostatic and hydration properties of DNA minor groove-binding by a heterocyclic diamidine by osmotic pressure.

PubMed

Erlitzki, Noa; Huang, Kenneth; Xhani, Suela; Farahat, Abdelbasset A; Kumar, Arvind; Boykin, David W; Poon, Gregory M K

2017-12-01

Previous investigations of sequence-specific DNA binding by model minor groove-binding compounds showed that the ligand/DNA complex was destabilized in the presence of compatible co-solutes. Inhibition was interpreted in terms of osmotic stress theory as the uptake of significant numbers of excess water molecules from bulk solvent upon complex formation. Here, we interrogated the AT-specific DNA complex formed with the symmetric heterocyclic diamidine DB1976 as a model for minor groove DNA recognition using both ionic (NaCl) and non-ionic cosolutes (ethylene glycol, glycine betaine, maltose, nicotinamide, urea). While the non-ionic cosolutes all destabilized the ligand/DNA complex, their quantitative effects were heterogeneous in a cosolute- and salt-dependent manner. Perturbation with NaCl in the absence of non-ionic cosolute showed that preferential hydration water was released upon formation of the DB1976/DNA complex. As salt probes counter-ion release from charged groups such as the DNA backbone, we propose that the preferential hydration uptake in DB1976/DNA binding observed in the presence of osmolytes reflects the exchange of preferentially bound cosolute with hydration water in the environs of the bound DNA, rather than a net uptake of hydration waters by the complex. Copyright © 2017 Elsevier B.V. All rights reserved.

DNA surface hybridization regimes

PubMed Central

Gong, Ping; Levicky, Rastislav

2008-01-01

Surface hybridization reactions, in which sequence-specific recognition occurs between immobilized and solution nucleic acids, are routinely carried out to quantify and interpret genomic information. Although hybridization is fairly well understood in bulk solution, the greater complexity of an interfacial environment presents new challenges to a fundamental understanding, and hence application, of these assays. At a surface, molecular interactions are amplified by the two-dimensional nature of the immobilized layer, which focuses the nucleic acid charge and concentration to levels not encountered in solution, and which impacts the hybridization behavior in unique ways. This study finds that, at low ionic strengths, an electrostatic balance between the concentration of immobilized oligonucleotide charge and solution ionic strength governs the onset of hybridization. As ionic strength increases, the importance of electrostatics diminishes and the hybridization behavior becomes more complex. Suppression of hybridization affinity constants relative to solution values, and their weakened dependence on the concentration of DNA counterions, indicate that the immobilized strands form complexes that compete with hybridization to analyte strands. Moreover, an unusual regime is observed in which the surface coverage of immobilized oligonucleotides does not significantly influence the hybridization behavior, despite physical closeness and hence compulsory interactions between sites. These results are interpreted and summarized in a diagram of hybridization regimes that maps specific behaviors to experimental ranges of ionic strength and probe coverage. PMID:18381819

Supercapacitors based on nitrogen-doped reduced graphene oxide and borocarbonitrides

NASA Astrophysics Data System (ADS)

Gopalakrishnan, K.; Moses, Kota; Govindaraj, A.; Rao, C. N. R.

2013-12-01

Nitrogen-doped reduced graphene oxide (RGO) samples with different nitrogen content, prepared by two different methods, as well as nitrogen-doped few-layer graphene have been investigated as supercapacitor electrodes. Two electrode measurements have been carried out both in aqueous (6M KOH) and in ionic liquid media. Nitrogen-doped reduced graphene oxides exhibit satisfactory specific capacitance, the values reaching 126F/g at a scan rate of 10mV/s in aqueous medium. Besides providing supercapacitor characteristics, the study has shown the nitrogen content and surface area to be important factors. High surface-area borocarbonitrides, BxCyNz, prepared by the urea route appear to be excellent supercapacitor electrode materials. Thus, BC4.5N exhibits a specific capacitance of 169F/g at a scan rate of 10mV/s in aqueous medium. In an ionic liquid medium, nitrogen-doped RGO and BC4.5N exhibit specific capacitance values of 258F/g and 240F/g at a scan rate of 5mV/s. The ionic liquid enables a larger operating voltage range of 0.0-2.5V compared to 0.0-1V in aqueous medium.

Fabrication of an ionic-liquid-based polymer monolithic column and its application in the fractionation of proteins from complex biosamples.

PubMed

Zhang, Doudou; Zhang, Qian; Bai, Ligai; Han, Dandan; Liu, Haiyan; Yan, Hongyuan

2018-05-01

An ionic-liquid-based polymer monolithic column was synthesized by free radical polymerization within the confines of a stainless-steel column (50 mm × 4.6 mm id). In the processes, ionic liquid and stearyl methacrylate were used as dual monomers, ethylene glycol dimethacrylate as the cross-linking agent, and polyethylene glycol 200 and isopropanol as co-porogens. Effects of the prepolymerization solution components on the properties of the resulting monoliths were studied in detail. Scanning electron microscopy, nitrogen adsorption-desorption measurements, and mercury intrusion porosimetry were used to investigate the morphology and pore size distribution of the prepared monoliths, which showed that the homemade ionic-liquid-based monolith column possessed a relatively uniform macropore structure with a total macropore specific surface area of 44.72 m 2 /g. Compared to a non-ionic-liquid-based monolith prepared under the same conditions, the ionic-liquid-based monolith exhibited excellent selectivity and high performance for separating proteins from complex biosamples, such as egg white, snailase, bovine serum albumin digest solution, human plasma, etc., indicating promising applications in the fractionation and analysis of proteins from the complex biosamples in proteomics research. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hybrid Nanowire Ion-to-Electron Transducers for Integrated Bioelectronic Circuitry.

PubMed

Carrad, D J; Mostert, A B; Ullah, A R; Burke, A M; Joyce, H J; Tan, H H; Jagadish, C; Krogstrup, P; Nygård, J; Meredith, P; Micolich, A P

2017-02-08

A key task in the emerging field of bioelectronics is the transduction between ionic/protonic and electronic signals at high fidelity. This is a considerable challenge since the two carrier types exhibit intrinsically different physics and are best supported by very different materials types-electronic signals in inorganic semiconductors and ionic/protonic signals in organic or bio-organic polymers, gels, or electrolytes. Here we demonstrate a new class of organic-inorganic transducing interface featuring semiconducting nanowires electrostatically gated using a solid proton-transporting hygroscopic polymer. This model platform allows us to study the basic transducing mechanisms as well as deliver high fidelity signal conversion by tapping into and drawing together the best candidates from traditionally disparate realms of electronic materials research. By combining complementary n- and p-type transducers we demonstrate functional logic with significant potential for scaling toward high-density integrated bioelectronic circuitry.

Deposition kinetics of colloidal particles at high ionic strengths

NASA Astrophysics Data System (ADS)

Cejas, Cesare; Monti, Fabrice; Truchet, Marine; Burnouf, Jean-Pierre; Tabeling, Patrick

Using microfluidic experiments, we describe the deposition of a fluid suspension of weakly brownian particles transported in a straight channel at small Reynolds numbers under conditions of high ionic strengths. Our studies fall in a regime where electrostatic interactions are neglected and particle-wall van der Waals interactions govern the deposition mechanism on channel walls. We calculate the deposition kinetics analytically for a wide range of physical parameters. We find that the theory agrees with numerical Langevin simulations, which both confirm the experimental results. From this analysis, we demonstrate a universal dimensionless deposition function described by contributions from advection-diffusion transport and adhesion interactions (Hamaker constant). Results show that we accurately confirm the theoretical expression for the deposition kinetics. From a surface science perspective, working in the van der Waals regime enables to measure the Hamaker constant, a task that would take much longer to perform with the standard AFM. Funding from Sanofi Recherche and ESPCI.

A New Electrochemical Sensor Based on Task-Specific Ionic Liquids-Modified Palm Shell Activated Carbon for the Determination of Mercury in Water Samples

PubMed Central

Ismaiel, Ahmed Abu; Aroua, Mohamed Kheireddine; Yusoff, Rozita

2014-01-01

In this study, a potentiometric sensor composed of palm shell activated carbon modified with trioctylmethylammonium thiosalicylate (TOMATS) was used for the potentiometric determination of mercury ions in water samples. The proposed potentiometric sensor has good operating characteristics towards Hg (II), including a relatively high selectivity; a Nernstian response to Hg (II) ions in a concentration range of 1.0 × 10−9 to 1.0 × 10−2 M, with a detection limit of 1 × 10−10 M and a slope of 44.08 ± 1.0 mV/decade; and a fast response time (∼5 s). No significant changes in electrode potential were observed when the pH was varied over the range of 3–9. Additionally, the proposed electrode was characterized by good selectivity towards Hg (II) and no significant interferences from other cationic or anionic species. PMID:25051034

Effects of humic acid and solution chemistry on the aggregation and dispersion of carboxyl-functionalized carbon black nanoparticles

NASA Astrophysics Data System (ADS)

Hwang, G.; Gomez-Flores, A.; Choi, S.; Han, Y., , Dr; Kim, H.

2017-12-01

The influence of humic acid, ionic strength and ionic species on the aggregation and dispersion of carboxyl-functionalized carbon black nanoparticles (CB-NPs) was systemically investigated in aqueous media. The experimental conditions of stability tests were selected to the changes in the solution chemistry (0.1-10 mM NaCl and 0.01-1 mM CaCl2) and in the presence/absence of humic acid (1 and 5 mg L-1) in an aquatic environment. The CB-NPs suspension was more rapidly settled in NaCl solution than in CaCl2. Specifically, in the case of NaCl, the aggregation rate of CB-NPs increased with ionic strength. Contrary, CB-NPs dispersed in CaCl2 were insensitive to the aggregation as the ionic strength increased; that was because specific adsorption of the divalent cation Ca2+ occurred since the zeta potential of the CB-NPs is reversed to a positive charge with increasing of the ionic strength. It was confirmed that humic acid greatly influences the stability of the CB-NPs. In particular, the dispersion of CB-NPs was improved in the whole range of ionic strengths of NaCl as well as of CaCl2. To support the results, the interaction energy between CB-NPs was calculated for each condition by using the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) and modified-DLVO theories. In the presence of humic acid, the improved stability of CB-NPs is attributed to the steric repulsive force.This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2015R1D1A3A01020766), the Ministry of Education (MOE) and National Research Foundation of Korea (NRF) through the Human Resource Training Project for Regional Innovation (2015H1C1A1035930) and Korea Energy and Mineral Resources Engineering Program (KEMREP).

Influence of MRI contrast media on histamine release from mast cells.

PubMed

Kun, Tomasz; Jakubowski, Lucjusz

2012-07-01

Mast cells, owing to diversity of secreted mediators, play a crucial role in the regulation of inflammatory response. Together with basophils, mast cells constitute a central pathogenetic element of anaphylactic (IgE-dependent) and anaphylactoid (IgE-independent) reactions. In severe cases, generalized degranulation of mast cells may cause symptoms of anaphylactic shock. The influence of the classical, iodine-based contrast media on mastocyte degranulation has been fully described. Our objective was to determine the influence of the gadolinium-based MRI contrast media on histamine release from mast cells and to compare the activity of ionic and non-ionic preparations of contrast media. To determine the intensity of mast cell degranulation, we used an experimental model based on mastocytes isolated from rat peritoneal fluid. Purified suspensions of mast cells were incubated with various concentrations of Gd-DTPA and Gd-DTPA-BMA, and solutions of PEG 600 which served as a non-toxic osmotic stimulus. The intensity of mast cell activation was presented as mean percentage of histamine released from cells after incubation. The obtained results demonstrate that both ionic and non-ionic preparations of the MRI contrast media are able to induce mast cell degranulation in vitro. It was also proved that the non-ionic MRI contrast media stimulate mast cells markedly more weakly than ionic contrast media at identical concentration. The aforementioned results may suggest a more profitable safety profile of the non-ionic contrast preparations. We may also conclude that triggering of mast cell degranulation after incubation with the solutions of MRI contrast media results from non-specific osmotic stimulation and direct toxicity of free ionic residues.

In silico insights into the solvation characteristics of the ionic liquid 1-methyltriethoxy-3-ethylimidazolium acetate for cellulosic biomass.

PubMed

Schutt, Timothy C; Bharadwaj, Vivek S; Hegde, Govind A; Johns, Adam J; Mark Maupin, C

2016-09-14

Lignocellulosic biomass is a domestically grown, sustainable, and potentially carbon-neutral feedstock for the production of liquid fuels and other value added chemicals. This underutilized renewable feedstock has the potential to alleviate some of the current socio-economic dependence on foreign petroleum supplies while stimulating rural economies. Unfortunately, the potential of biomass has largely been underdeveloped due to the recalcitrant nature of lignocellulosic materials. Task-specific ionic liquids (ILs) have shown considerable promise as an alternative non-aqueous solvent for solvation and deconstruction of lignocellulose in the presence of metal chloride catalyst or enzymes. Recently it has been hypothesized that adding oxygen atoms to the tail of an imidazolium cation would alleviate some of the negative characteristics of the ILs by increasing mass transport properties, and decreasing IL deactivation of enzymes, while at the same time retaining favorable solvation characteristics for lignocellulose. Reported here are fully atomistic molecular dynamic simulations of 1-methyltriethoxy-3-ethylimidazolium acetate ([Me-(OEt)3-Et-IM(+)] [OAc(-)]) that elucidate promising molecular-level details pertaining to the solvation characteristics of model compounds of cellulose, and IL-induced side-chain and ring puckering conformations. It is found that the anion interactions with the saccharide induce alternate ring puckering conformations from those seen in aqueous environments (i.e.(1)C4), while the cation interactions are found to influence the conformation of the ω dihedral. These perturbations in saccharide structures are discussed in the context of their contribution to the disruption of hydrogen bonding in cellulosic architecture and their role in solvation.

Free silanols and ionic liquids as their suppressors in liquid chromatography.

PubMed

Buszewska-Forajta, Magdalena; Markuszewski, Michał J; Kaliszan, Roman

2018-07-20

In this review, we will firstly discuss the types and the general properties of silica, focusing on the silica support used in chromatography and capillary electrophoresis. Additionally, the characterization of functional groups (silanols and siloxanes) will be considered in terms of activity of the stationary phases. We will then discuss physical chemistry of the stationary phases applied in liquid chromatography and capillary electrophoresis. The use of ionic liquids as a silanols' suppressors will be presented in the next parts of the study, along with the examples of specific applications. The review is completed with conclusions and an outlook for the future developments in the area of analytical applications of ionic liquids. Copyright © 2018 Elsevier B.V. All rights reserved.

[Bis(imidazolyl)-BH₂]+[bis-(triazolyl)-BH₂]- Ionic Liquids with High Density and Energy Capacity.

PubMed

Jiao, Nianming; Li, Hao; Zhang, Yanqiang; Liu, Long; Zhang, Suojiang

2018-05-15

[Bis(imidazolyl)-BH₂]+[bis(triazolyl)-BH₂]- and [bis- (imidazolyl)-BH₂]+[tris(triazolyl)-BH]- were first synthesized, whose cations and anions were all functionalized with B-H groups and azoles. As B-H groups contributing to hypergolic activity and azole groups improving the energy outputs, the resulting ionic liquids exhibited ignition delay time as low as 20 ms and energy output as high as 461.1 kJ mol-1. Besides, densities (1.07-1.22 g∙cm-3) and density-specific impulse (ρIsp, ~ 360 s g cm-3) reach to relatively high level. It has a great promising for those ionic liquids as sustainable rocket fuels. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A 3D-analysis of cluster formation and dynamics of the X(-)-benzene (X = F, Cl, Br, I) ionic dimer solvated by Ar atoms.

PubMed

Albertí, Margarita; Huarte-Larrañaga, Fermín; Aguilar, Antonio; Lucas, José M; Pirani, Fernando

2011-05-14

The specific influence of X(-) ions (X = F,Cl, Br, I) in the solvation process of halide-benzene (X(-)-Bz) ionic heterodimers by Ar atoms is investigated by means of molecular dynamic (MD) simulations. The gradual evolution from cluster rearrangement to solvation dynamics is discussed by considering ensembles of n (n = 1-15 and n = 30) Ar atoms around the X(-)-Bz stable ionic dimers. The potential energy surfaces employed are based on an atom/ion-atom and atom/ion-bond decomposition, which has been developed previously by some of the authors. The outcome of the dynamics is analyzed by employing radial distribution functions (RDF) and tridimensional (3D) probability densities.

Synergistic effects of mixing sulfone and ionic liquid as safe electrolytes for lithium sulfur batteries.

PubMed

Liao, Chen; Guo, Bingkun; Sun, Xiao-Guang; Dai, Sheng

2015-01-01

A strategy of mixing both an ionic liquid and sulfone is reported to give synergistic effects of reducing viscosity, increasing ionic conductivity, reducing polysulfide dissolution, and improving safety. The mixtures of ionic liquids and sulfones also show distinctly different physicochemical properties, including thermal properties and crystallization behavior. By using these electrolytes, lithium sulfur batteries assembled with lithium and mesoporous carbon composites show a reversible specific capacity of 1265 mAh g(-1) (second cycle) by using 40 % 1.0 M lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) in N-methyl-N-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide with 60 % 1.0 M LiTFSI in methylisopropylsulfone in the first cycle. This capacity is slightly lower than that obtained in pure 1.0 M LiTFSI as the sulfone electrolyte; however, it exhibits excellent cycling stability and remains as high as 655 mAh g(-1) even after 50 cycles. This strategy provides a method to alleviate polysulfide dissolution and redox shuttle phenomena, at the same time, with improved ionic conductivity. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Relation between Vaporization Enthalpies and Viscosities: Eyring's Theory Applied to Selected Ionic Liquids.

PubMed

Bonsa, Anne-Marie; Paschek, Dietmar; Zaitsau, Dzmitry H; Emel'yanenko, Vladimir N; Verevkin, Sergey P; Ludwig, Ralf

2017-05-19

Key properties for the use of ionic liquids as electrolytes in batteries are low viscosities, low vapor pressure and high vaporization enthalpies. Whereas the measurement of transport properties is well established, the determination of vaporization enthalpies of these extremely low volatile compounds is still a challenge. At a first glance both properties seem to describe different thermophysical phenomena. However, eighty years ago Eyring suggested a theory which related viscosities and vaporization enthalpies to each other. The model is based on Eyring's theory of absolute reaction rates. Recent attempts to apply Eyring's theory to ionic liquids failed. The motivation of our study is to show that Eyring's theory works, if the assumptions specific for ionic liquids are fulfilled. For that purpose we measured the viscosities of three well selected protic ionic liquids (PILs) at different temperatures. The temperature dependences of viscosities were approximated by the Vogel-Fulcher-Tamann (VFT) relation and extrapolated to the high-temperature regime up to 600 K. Then the VFT-data could be fitted to the Eyring-model. The values of vaporization enthalpies for the three selected PILs predicted by the Eyring model have been very close to the experimental values measured by well-established techniques. We conclude that the Eyring theory can be successfully applied to the chosen set of PILs, if the assumption that ionic pairs of the viscous flow in the liquid and the ionic pairs in the gas phase are similar is fulfilled. It was also noticed that proper transfer of energies can be only derived if the viscosities and the vaporization energies are known for temperatures close to the liquid-gas transition temperature. The idea to correlate easy measurable viscosities of ionic liquids with their vaporization enthalpies opens a new way for a reliable assessment of these thermodynamic properties for a broad range of ionic liquids. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tension in Skinned Frog Muscle Fibers in Solutions of Varying Ionic Strength and Neutral Salt Composition

PubMed Central

Gordon, A. M.; Godt, R. E.; Donaldson, S. K. B.; Harris, C. E.

1973-01-01

The maximal calcium-activated isometric tension produced by a skinned frog single muscle fiber falls off as the ionic strength of the solution bathing this fiber is elevated declining to zero near 0.5 M as the ionic strength is varied using KCl. When other neutral salts are used, the tension always declines at high ionic strength, but there is some difference between the various neutral salts used. The anions and cations can be ordered in terms of their ability to inhibit the maximal calcium-activated tension. The order of increasing inhibition of tension (decreasing tension) at high ionic strength for anions is propionate- ≃ SO4 -- < Cl- < Br-. The order of increasing inhibition of calcium-activated tension for cations is K+ ≃ Na+ ≃ TMA+ < TEA+ < TPrA+ < TBuA+. The decline of maximal calcium-activated isometric tension with elevated salt concentration (ionic strength) can quantitatively explain the decline of isometric tetanic tension of a frog muscle fiber bathed in a hypertonic solution if one assumes that the internal ionic strength of a muscle fiber in normal Ringer's solution is 0.14–0.17 M. There is an increase in the base-line tension of a skinned muscle fiber bathed in a relaxing solution (no added calcium and 3 mM EGTA) of low ionic strength. This tension, which has no correlate in the intact fiber in hypotonic solutions, appears to be a noncalcium-activated tension and correlates more with a declining ionic strength than with small changes in [MgATP], [Mg], pH buffer, or [EGTA]. It is dependent upon the specific neutral salts used with cations being ordered in increasing inhibition of this noncalcium-activated tension (decreasing tension) as TPrA+ < TMA+ < K+ ≃ Na+. Measurements of potentials inside these skinned muscle fibers bathed in relaxing solutions produced occasional small positive values (<6 mV) which were not significantly different from zero. PMID:4543066

Phytoremediation of Ionic and Methyl Mercury Pollution

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

Meagher, Richard B.

Phytoremediation is defined as the use of plants to extract, resist, detoxify, and/or sequester toxic environmental pollutants. The long-term goal of the proposed research is to develop and test highly productive, field-adapted plant species that have been engineered for the phytoremediation of mercury. A variety of different genes, which should enable plants to clean mercury polluted sites are being tested as tools for mercury phytoremediation, first in model laboratory plants and then in potential field species. Several of these genes have already been shown to enhance mercury phytoremediation. Mercury pollution is a serious, world-wide problem affecting the health of humanmore » and wildlife populations. Environmentally, the most serious mercury threat is the production of methylmercury (CH3Hg+) by native bacteria at mercury contaminated wetland sites. Methylmercury is inherently more toxic than metallic (Hg(0)) or ionic (Hg(II)) mercury, and because methylmercury is prolifically biomagnified up the food chain, it poses the most immediate danger to animal populations. We have successfully engineered two model plants, Arabidopsis and tobacco, to use the bacterial merB gene to convert methylmercury to less toxic ionic mercury and to use the bacterial merA gene to further detoxify ionic mercury to the least toxic form of mercury, metallic mercury. Plants expressing both MerA and MerB proteins detoxify methylmercury in two steps to the metallic form. These plants germinate, grow, and set seed at normal growth rates on levels of methylmercury or ionic mercury that are lethal to normal plants. Our newest efforts involve engineering plants with several additional bacterial and plant genes that allow for higher levels of mercury resistance and mercury hyperaccumulation. The potential for these plants to hyperaccumulate mercury was further advanced by developing constitutive, aboveground, and root-specific gene expression systems. Our current strategy is to engineer plants to control the chemical speciation, electrochemical state, transport, and aboveground binding of mercury in order to manage this toxicant. To advance this mercury phytoremediation strategy, our planned research focuses on the following Specific Aims: (1) to increase the transport of mercury to aboveground tissue; (2) to identify small mercury binding peptides that enhance hyperaccumulation aboveground; (3) to test the ability of multiple genes acting together to enhance resistance and hyperaccumulation; (4) to construct a simple molecular system for creating male/female sterility, allowing engineered grass, shrub, and tree species to be released indefinitely at contaminated sites; (5) to test the ability of transgenic cottonwood and rice plants to detoxify ionic mercury and prevent methylmercury release from contaminated sediment; and (6) to initiate field testing with transgenic cottonwood and rice for the remediation of methylmercury and ionic mercury. The results of these experiments will enable the phytoremediation of methyl- and ionic mercury by a wide spectrum of deep-rooted, fast-growing plants adapted to diverse environments. We have made significant progress on all six of these specific aims as summarized below.« less

[Determination of solubility parameters for asymmetrical dicationic ionic liquids by inverse gas chromatography].

PubMed

Wang, Jun; Yang, Xuzhao; Wu, Jinchao; Song, Hao; Zou, Wenyuan

2015-12-01

Inverse gas chromatographic (IGC) technology was used to determine the solubility parameters of three asymmetrical dicationic ionic liquids ([ PyC5Pi] [ NTf2]2, [MpC5Pi] [NTf2]2 and [PyC6Pi] [NTf2]2) at 343.15-363.15 K. Five alkanes were applied as test probes including octane (n-C8) , decane (n-C10), dodecane (n-C12), tetradecane (n-C14), hexadecane (n-C16). Some thermodynamic parameters were obtained by IGC data analysis, such as the specific retention volumes of the solvents (V0(g)), the molar enthalpies of sorption (ΔHs(1)), the partial molar enthalpies of mixing at infinite dilution (ΔH∞91)), the molar enthalpies of vaporization (ΔH)v)), the activity coefficients at infinite dilution (Ω∞(1)), and Flory-Huggins interaction parameters (χ∞(12)) between ionic liquids and probes. The solubility parameters (δ2) of the three dicationic ionic liquids at room temperature (298.15 K) were 28.52-32.66 (J x cm(-3)) ½. The solubility parameters (δ2) of cationic structure with 4-methyl morpholine are bigger than those of the cationic structure with pyridine. The bigger the solubility parameter (δ2) is, the more the carbon numbers of linking group of the ionic liquids are. The results are of great importance to the study of the solution behavior and the applications of ionic liquid.

Fluorophotometric determination of critical micelle concentration (CMC) of ionic and non-ionic surfactants with carbon dots via Stokes shift.

PubMed

Lavkush Bhaisare, Mukesh; Pandey, Sunil; Shahnawaz Khan, M; Talib, Abou; Wu, Hui-Fen

2015-01-01

A new and facile method for the determination of critical micelle concentration (CMC) of ionic and non-ionic surfactants is proposed in this article. Carbon dots exhibited substantial fluorescence and therefore enhanced the sensitivity of this evaluation. Understanding the formation of surfactant micelles is vital for the applications of biomedicine such as drug fabrication and smart molecular vehicles in delivering therapeutic dosage to various molecular sites. The fluorescence property of carbon dots was utilized for the first time to estimate the critical micelle concentration of surfactants. The central concept of the approach is based on the Stokes shift determination of a system composed of constant amount of carbon dots with varying concentrations of ionic and non-ionic surfactants. The synthesized carbon dots were characterized by FTIR, TEM, XRD, Raman, UV, and fluorescence spectroscope. The carbon dots were excited at 280 nm so as to obtain maximum emission for the Stokes shift measurement. The CMC value of cetyltrimethyl ammonium bromide (CTAB), sodium dodecyl sulfate (SDS), Triton X-100, dodecyldimethyl(3-sulfopropyl)ammonium hydroxide (SB-12) evaluated by this approach was found to be 0.98, 7.3, 0.19, and 3.5mM, respectively. The signals of spectra were assigned and explained in terms of both electron transitions between specific molecular orbital and the interaction with solvent. Copyright © 2014 Elsevier B.V. All rights reserved.

Rotational dynamics of coumarin-153 and 4-aminophthalimide in 1-ethyl-3-methylimidazolium alkylsulfate ionic liquids: effect of alkyl chain length on the rotational dynamics.

PubMed

Das, Sudhir Kumar; Sarkar, Moloy

2012-01-12

Rotational dynamics of two neutral organic solutes, coumarin-153 (C-153) and 4-aminophthalimide (AP), with only the latter having hydrogen-bond-donating ability, has been investigated in a series of 1-ethyl-3-methylimidazolium alkyl sulfate ionic liquids as a function of temperature. The ionic liquids differ only in the length of the linear alkyl side chain (alkyl = ethyl, butyl, hexyl, and octyl) on the anionic moiety. The present study has been undertaken to examine the role of alkyl side chains on the rotational dynamics of the two solutes in these ionic liquids. Analysis of the results using Stokes-Einstein-Debye hydrodynamic theory indicates that the rotational dynamics of C-153 lies between the stick and slip boundary condition in the ethyl analogue and finally reaches subslip condition as in case of the octyl substituent. The observed rotational behavior of C-153 has been explained on the basis of an increase in the size of the solvent, which offers lower friction for solute rotation. On the other hand, AP shows superstick behavior in the ethyl system and exceeds the stick limit in the octyl derivative. Superstick behavior of AP has been attributed to the specific hydrogen-bonding interaction between AP and the sulfate moiety. Proton NMR investigation confirms the hydrogen-bonding interaction between the N-H hydrogen of AP and the ionic liquid. The decrease in rotational coupling constant values for AP with increasing length of alkyl side chains has been attributed to the decrease in the solute-solvent-specific interaction with an increase in the alkyl side chain length on the sulfate moiety.

Expression of Aspergillus niger CAZymes is determined by compositional changes in wheat straw generated by hydrothermal or ionic liquid pretreatments.

PubMed

Daly, Paul; van Munster, Jolanda M; Blythe, Martin J; Ibbett, Roger; Kokolski, Matt; Gaddipati, Sanyasi; Lindquist, Erika; Singan, Vasanth R; Barry, Kerrie W; Lipzen, Anna; Ngan, Chew Yee; Petzold, Christopher J; Chan, Leanne Jade G; Pullan, Steven T; Delmas, Stéphane; Waldron, Paul R; Grigoriev, Igor V; Tucker, Gregory A; Simmons, Blake A; Archer, David B

2017-01-01

The capacity of fungi, such as Aspergillus niger, to degrade lignocellulose is harnessed in biotechnology to generate biofuels and high-value compounds from renewable feedstocks. Most feedstocks are currently pretreated to increase enzymatic digestibility: improving our understanding of the transcriptomic responses of fungi to pretreated lignocellulosic substrates could help to improve the mix of activities and reduce the production costs of commercial lignocellulose saccharifying cocktails. We investigated the responses of A. niger to untreated, ionic liquid and hydrothermally pretreated wheat straw over a 5-day time course using RNA-seq and targeted proteomics. The ionic liquid pretreatment altered the cellulose crystallinity while retaining more of the hemicellulosic sugars than the hydrothermal pretreatment. Ionic liquid pretreatment of straw led to a dynamic induction and repression of genes, which was correlated with the higher levels of pentose sugars saccharified from the ionic liquid-pretreated straw. Hydrothermal pretreatment of straw led to reduced levels of transcripts of genes encoding carbohydrate-active enzymes as well as the derived proteins and enzyme activities. Both pretreatments abolished the expression of a large set of genes encoding pectinolytic enzymes. These reduced levels could be explained by the removal of parts of the lignocellulose by the hydrothermal pretreatment. The time course also facilitated identification of temporally limited gene induction patterns. The presented transcriptomic and biochemical datasets demonstrate that pretreatments caused modifications of the lignocellulose, to both specific structural features as well as the organisation of the overall lignocellulosic structure, that determined A. niger transcript levels. The experimental setup allowed reliable detection of substrate-specific gene expression patterns as well as hitherto non-expressed genes. Our data suggest beneficial effects of using untreated and IL-pretreated straw, but not HT-pretreated straw, as feedstock for CAZyme production.

Design principles from multiscale simulations to predict nanostructure in self-assembling ionic liquids

DOE PAGES

Nebgen, Benjamin Tyler; Magurudeniya, Harsha D.; Kwock, Kevin Wen Chi; ...

2017-07-18

Molecular dynamics simulations (up to the nanoscale) were performed on the 3-methyl-1-pentylimidazolium ionic liquid cation paired with three anions; chloride, nitrate, and thiocyanate as aqueous mixtures, using the effective fragment potential (EFP) method, a computationally inexpensive way of modeling intermolecular interactions. The simulations provided insight (preferred geometries, radial distribution functions and theoretical proton NMR resonances) into the interactions within the ionic domain and are validated against 1H NMR spectroscopy and small- and wide-angle X-ray scattering experiments on 1-decyl-3-methylimidazolium. Ionic liquids containing thiocyanate typically resist gelation and form poorly ordered lamellar structures upon mixing with water. Conversely, chloride, a strongly coordinatingmore » anion, normally forms strong physical gels and produces well-ordered nanostructures adopting a variety of structural motifs over a very wide range of water compositions. Nitrate is intermediate in character, whereby upon dispersal in water it displays a range of viscosities and self-assembles into nanostructures with considerable variability in the fidelity of ordering and symmetry, as a function of water content in the binary mixtures. The observed changes in the macro and nanoscale characteristics were directly correlated to ionic domain structures and intermolecular interactions as theoretically predicted by the analysis of MD trajectories and calculated RDFs. Specifically, both chloride and nitrate are positioned in the plane of the cation. Anion to cation proximity is dependent on water content. Thiocyanate is more susceptible to water insertion into the second solvent shell. Experimental 1H NMR chemical shifts monitor the site-specific competition dependence with water content in the binary mixtures. As a result, thiocyanate preferentially sits above and below the aromatic ring plane, a state disallowing interaction with the protons on the imidazolium ring.« less

Design principles from multiscale simulations to predict nanostructure in self-assembling ionic liquids.

PubMed

Nebgen, Benjamin T; Magurudeniya, Harsha D; Kwock, Kevin W C; Ringstrand, Bryan S; Ahmed, Towfiq; Seifert, Sönke; Zhu, Jian-Xin; Tretiak, Sergei; Firestone, Millicent A

2017-12-14

Molecular dynamics simulations (up to the nanoscale) were performed on the 3-methyl-1-pentylimidazolium ionic liquid cation paired with three anions; chloride, nitrate, and thiocyanate as aqueous mixtures, using the effective fragment potential (EFP) method, a computationally inexpensive way of modeling intermolecular interactions. The simulations provided insight (preferred geometries, radial distribution functions and theoretical proton NMR resonances) into the interactions within the ionic domain and are validated against 1 H NMR spectroscopy and small- and wide-angle X-ray scattering experiments on 1-decyl-3-methylimidazolium. Ionic liquids containing thiocyanate typically resist gelation and form poorly ordered lamellar structures upon mixing with water. Conversely, chloride, a strongly coordinating anion, normally forms strong physical gels and produces well-ordered nanostructures adopting a variety of structural motifs over a very wide range of water compositions. Nitrate is intermediate in character, whereby upon dispersal in water it displays a range of viscosities and self-assembles into nanostructures with considerable variability in the fidelity of ordering and symmetry, as a function of water content in the binary mixtures. The observed changes in the macro and nanoscale characteristics were directly correlated to ionic domain structures and intermolecular interactions as theoretically predicted by the analysis of MD trajectories and calculated RDFs. Specifically, both chloride and nitrate are positioned in the plane of the cation. Anion to cation proximity is dependent on water content. Thiocyanate is more susceptible to water insertion into the second solvent shell. Experimental 1 H NMR chemical shifts monitor the site-specific competition dependence with water content in the binary mixtures. Thiocyanate preferentially sits above and below the aromatic ring plane, a state disallowing interaction with the protons on the imidazolium ring.

Direct Ionic Regulation of the Activity of Myo-Inositol Biosynthesis Enzymes in Mozambique Tilapia

PubMed Central

Villarreal, Fernando D.; Kültz, Dietmar

2015-01-01

Myo-inositol (Ins) is a major compatible osmolyte in many cells, including those of Mozambique tilapia (Oreochromis mossambicus). Ins biosynthesis is highly up-regulated in tilapia and other euryhaline fish exposed to hyperosmotic stress. In this study, enzymatic regulation of two enzymes of Ins biosynthesis, Ins phosphate synthase (MIPS) and inositol monophosphatase (IMPase), by direct ionic effects is analyzed. Specific MIPS and IMPase isoforms from Mozambique tilapia (MIPS-160 and IMPase 1) were selected based on experimental, phylogenetic, and structural evidence supporting their role for Ins biosynthesis during hyperosmotic stress. Recombinant tilapia IMPase 1 and MIPS-160 activity was assayed in vitro at ionic conditions that mimic changes in the intracellular milieu during hyperosmotic stress. The in vitro activities of MIPS-160 and IMPase 1 are highest at alkaline pH of 8.8. IMPase 1 catalytic efficiency is strongly increased during hyperosmolality (particularly for the substrate D-Ins-3-phosphate, Ins-3P), mainly as a result of [Na+] elevation. Furthermore, the substrate-specificity of IMPase 1 towards D-Ins-1-phosphate (Ins-1P) is lower than towards Ins-3P. Because MIPS catalysis results in Ins-3P this results represents additional evidence for IMPase 1 being the isoform that mediates Ins biosynthesis in tilapia. Our data collectively demonstrate that the Ins biosynthesis enzymes are activated under ionic conditions that cells are exposed to during hypertonicity, resulting in Ins accumulation, which, in turn, results in restoration of intracellular ion homeostasis. We propose that the unique and direct ionic regulation of the activities of Ins biosynthesis enzymes represents an efficient biochemical feedback loop for regulation of intracellular physiological ion homeostasis during hyperosmotic stress. PMID:26066044

Direct Ionic Regulation of the Activity of Myo-Inositol Biosynthesis Enzymes in Mozambique Tilapia.

PubMed

Villarreal, Fernando D; Kültz, Dietmar

2015-01-01

Myo-inositol (Ins) is a major compatible osmolyte in many cells, including those of Mozambique tilapia (Oreochromis mossambicus). Ins biosynthesis is highly up-regulated in tilapia and other euryhaline fish exposed to hyperosmotic stress. In this study, enzymatic regulation of two enzymes of Ins biosynthesis, Ins phosphate synthase (MIPS) and inositol monophosphatase (IMPase), by direct ionic effects is analyzed. Specific MIPS and IMPase isoforms from Mozambique tilapia (MIPS-160 and IMPase 1) were selected based on experimental, phylogenetic, and structural evidence supporting their role for Ins biosynthesis during hyperosmotic stress. Recombinant tilapia IMPase 1 and MIPS-160 activity was assayed in vitro at ionic conditions that mimic changes in the intracellular milieu during hyperosmotic stress. The in vitro activities of MIPS-160 and IMPase 1 are highest at alkaline pH of 8.8. IMPase 1 catalytic efficiency is strongly increased during hyperosmolality (particularly for the substrate D-Ins-3-phosphate, Ins-3P), mainly as a result of [Na+] elevation. Furthermore, the substrate-specificity of IMPase 1 towards D-Ins-1-phosphate (Ins-1P) is lower than towards Ins-3P. Because MIPS catalysis results in Ins-3P this results represents additional evidence for IMPase 1 being the isoform that mediates Ins biosynthesis in tilapia. Our data collectively demonstrate that the Ins biosynthesis enzymes are activated under ionic conditions that cells are exposed to during hypertonicity, resulting in Ins accumulation, which, in turn, results in restoration of intracellular ion homeostasis. We propose that the unique and direct ionic regulation of the activities of Ins biosynthesis enzymes represents an efficient biochemical feedback loop for regulation of intracellular physiological ion homeostasis during hyperosmotic stress.

POWER AND THERMAL TECHNOLOGIES FOR AIR AND SPACE-SCIENTIFIC RESEARCH PROGRAM Delivery Order 0018: Single Ion Conducting Solid-State Lithium Electrochemical Technologies (Task 4)

DTIC Science & Technology

2010-08-01

a mathematical equation relates the cathode reaction reversible electric potential to the lithium content of the cathode electrode. Based on the...Transport of Lithium in the Cell Cathode Active Material The Nernst -Einstein relation linking the lithium-ion mass diffusivity and its ionic...transient, isothermal and isobaric conditions. The differential model equation describing the lithium diffusion and accumulation in a spherical, active

Surface science and model catalysis with ionic liquid-modified materials.

PubMed

Steinrück, H-P; Libuda, J; Wasserscheid, P; Cremer, T; Kolbeck, C; Laurin, M; Maier, F; Sobota, M; Schulz, P S; Stark, M

2011-06-17

Materials making use of thin ionic liquid (IL) films as support-modifying functional layer open up a variety of new possibilities in heterogeneous catalysis, which range from the tailoring of gas-surface interactions to the immobilization of molecularly defined reactive sites. The present report reviews recent progress towards an understanding of "supported ionic liquid phase (SILP)" and "solid catalysts with ionic liquid layer (SCILL)" materials at the microscopic level, using a surface science and model catalysis type of approach. Thin film IL systems can be prepared not only ex-situ, but also in-situ under ultrahigh vacuum (UHV) conditions using atomically well-defined surfaces as substrates, for example by physical vapor deposition (PVD). Due to their low vapor pressure, these systems can be studied in UHV using the full spectrum of surface science techniques. We discuss general strategies and considerations of this approach and exemplify the information available from complementary methods, specifically photoelectron spectroscopy and surface vibrational spectroscopy. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Local Order-Disorder Transition Driving by Structural Heterogeneity in a Benzyl Functionalized Ionic Liquid.

PubMed

Faria, Luiz F O; Paschoal, Vitor H; Lima, Thamires A; Ferreira, Fabio F; Freitas, Rafael S; Ribeiro, Mauro C C

2017-10-26

A local order-disorder transition has been disclosed in the thermophysical behavior of the ionic liquid 1-benzyl-3-methylimidazolium dicyanamide, [Bzmim][N(CN) 2 ], and its microscopic nature revealed by spectroscopic techniques. Differential scanning calorimetry and specific heat measurements show a thermal event of small enthalpy variation taking place in the range 250-260 K, which is not due to crystallization or melting. Molecular dynamic simulations and X-ray diffraction measurements have been used to discuss the segregation of domains in the liquid structure of [Bzmim][N(CN) 2 ]. Raman and NMR spectroscopy measurements as a function of temperature indicate that the microscopic origin of the event observed in the calorimetric measurements comes from structural rearrangement involving the benzyl group. The results indicate that the characteristic structural heterogeneity allow for rearrangements within local domains implying the good glass-forming ability for the low viscosity ionic liquid [Bzmim][N(CN) 2 ]. This work sheds light on our understanding of the microscopic origin behind complex thermal behavior of ionic liquids.

Thermally-responsive, nonflammable phosphonium ionic liquid electrolytes for lithium metal batteries: operating at 100 degrees celsius† †Electronic supplementary information (ESI) available: Detailed ionic liquids synthesis, characterization, conductivity, cyclic voltammetry, battery cycling and those of other compositions; SEM images; energy density calculation. See DOI: 10.1039/c5sc01518a Click here for additional data file.

PubMed Central

Lin, X.; Kavian, R.; Lu, Y.; Hu, Q.; Shao-Horn, Y.

2015-01-01

Rechargeable batteries such as Li ion/Li metal batteries are widely used in the electronics market but the chemical instability of the electrolyte limits their use in more demanding environmental conditions such as in automotive, oil exploration, or mining applications. In this study, a series of alkyl phosphonium ionic liquid electrolyte are described with high thermal stability and solubility for LiTFSI. A lithium metal battery (LMB) containing a tailored phosphonium ionic liquid/LiTFSI electrolyte operates at 100 °C with good specific capacities and cycling stability. Substantial capacity is maintained during 70 cycles or 30 days. Instant on-off battery operation is realized via the significant temperature dependence of the electrolyte material, demonstrating the robustness and potential for use at high temperature. PMID:28757963

Graphitic carbon nitride nanosheet electrode-based high-performance ionic actuator

PubMed Central

Wu, Guan; Hu, Ying; Liu, Yang; Zhao, Jingjing; Chen, Xueli; Whoehling, Vincent; Plesse, Cédric; Nguyen, Giao T. M.; Vidal, Frédéric; Chen, Wei

2015-01-01

Ionic actuators have attracted attention due to their remarkably large strain under low-voltage stimulation. Because actuation performance is mainly dominated by the electrochemical and electromechanical processes of the electrode layer, the electrode material and structure are crucial. Here, we report a graphitic carbon nitride nanosheet electrode-based ionic actuator that displays high electrochemical activity and electromechanical conversion abilities, including large specific capacitance (259.4 F g−1) with ionic liquid as the electrolyte, fast actuation response (0.5±0.03% in 300 ms), large electromechanical strain (0.93±0.03%) and high actuation stability (100,000 cycles) under 3 V. The key to the high performance lies in the hierarchical pore structure with dominant size <2 nm, optimal pyridinic nitrogen active sites (6.78%) and effective conductivity (382 S m−1) of the electrode. Our study represents an important step towards artificial muscle technology in which heteroatom modulation in electrodes plays an important role in promoting electrochemical actuation performance. PMID:26028354

Protic ionic liquid as additive on lipase immobilization using silica sol-gel.

PubMed

de Souza, Ranyere Lucena; de Faria, Emanuelle Lima Pache; Figueiredo, Renan Tavares; Freitas, Lisiane dos Santos; Iglesias, Miguel; Mattedi, Silvana; Zanin, Gisella Maria; dos Santos, Onélia Aparecida Andreo; Coutinho, João A P; Lima, Álvaro Silva; Soares, Cleide Mara Faria

2013-03-05

Ionic liquids (ILs) have evolved as a new type of non-aqueous solvents for biocatalysis, mainly due to their unique and tunable physical properties. A number of recent review papers have described a variety of enzymatic reactions conducted in IL solutions, on the other hand, to improve the enzyme's activity and stability in ILs; major methods being explored include the enzyme immobilization (on solid support, sol-gel, etc.), protic ionic liquids used as an additive process. The immobilization of the lipase from Burkholderia cepacia by the sol-gel technique using protic ionic liquids (PIL) as additives to protect against inactivation of the lipase due to release of alcohol and shrinkage of the gel during the sol-gel process was investigated in this study. The influence of various factors such as the length of the alkyl chain of protic ionic liquids (monoethanolamine-based) and a concentration range between 0.5 and 3.0% (w/v) were evaluated. The resulting hydrophobic matrices and immobilized lipases were characterised with regard to specific surface area, adsorption-desorption isotherms, pore volume (V(p)) and size (d(p)) according to nitrogen adsorption and scanning electron microscopy (SEM), physico-chemical properties (thermogravimetric - TG, differential scanning calorimetry - DSC and Fourier transform infrared spectroscopy - FTIR) and the potential for ethyl ester and emulsifier production. The total activity yields (Y(a)) for matrices of immobilized lipase employing protic ionic liquids as additives always resulted in higher values compared with the sample absent the protic ionic liquids, which represents 35-fold increase in recovery of enzymatic activity using the more hydrophobic protic ionic liquids. Compared with arrays of the immobilized biocatalyst without additive, in general, the immobilized biocatalyst in the presence of protic ionic liquids showed increased values of surface area (143-245 m(2) g(-1)) and pore size (19-38 Å). Immobilization with protic ionic liquids also favoured reduced mass loss according to TG curves (always less than 42.9%) when compared to the immobilized matrix without protic ionic liquids (45.1%), except for the sample containing 3.0% protic ionic liquids (46.5%), verified by thermogravimetric analysis. Ionic liquids containing a more hydrophobic alkyl group in the cationic moiety were beneficial for recovery of the activity of the immobilized lipase. The physico-chemical characterization confirmed the presence of the enzyme and its immobilized derivatives obtained in this study by identifying the presence of amino groups, and profiling enthalpy changes of mass loss. Copyright © 2013 Elsevier Inc. All rights reserved.

Performance of solid state supercapacitors based on polymer electrolytes containing different ionic liquids

NASA Astrophysics Data System (ADS)

Tiruye, Girum Ayalneh; Muñoz-Torrero, David; Palma, Jesus; Anderson, Marc; Marcilla, Rebeca

2016-09-01

Four Ionic Liquid based Polymer Electrolytes (IL-b-PE) were prepared by blending a Polymeric Ionic Liquid, Poly(diallyldimethylammonium) bis(trifluoromethanesulfonyl)imide (PILTFSI), with four different ionic liquids: 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR14TFSI) (IL-b-PE1), 1-butyl-1-methylpyrrolidinium bis(fluorosulfonyl)imide (PYR14FSI) (IL-b-PE2), 1-(2-hydroxy ethyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (HEMimTFSI) (IL-b-PE3), and 1-Butyl-1-methylpyrrolidinium dicyanamide, (PYR14DCA) (IL-b-PE4). Physicochemical properties of IL-b-PE such as ionic conductivity, thermal and electrochemical stability were found to be dependent on the IL properties. For instance, ionic conductivity was significantly higher for IL-b-PE2 and IL-b-PE4 containing IL with small size anions (FSI and DCA) than IL-b-PE1 and IL-b-PE3 bearing IL with bigger anion (TFSI). On the other hand, wider electrochemical stability window (ESW) was found for IL-b-PE1 and IL-b-PE2 having ILs with electrochemically stable pyrrolidinium cation and FSI and TFSI anions. Solid state Supercapacitors (SCs) were assembled with activated carbon electrodes and their electrochemical performance was correlated with the polymer electrolyte properties. Best performance was obtained with SC having IL-b-PE2 that exhibited a good compromise between ionic conductivity and electrochemical window. Specific capacitance (Cam), real energy (Ereal) & real power densities (Preal) as high as 150 F g-1, 36 Wh kg-1 & 1170 W kg-1 were found at operating voltage of 3.5 V.

Non-specific binding of Na+ and Mg2+ to RNA determined by force spectroscopy methods

PubMed Central

Bizarro, C. V.; Alemany, A.; Ritort, F.

2012-01-01

RNA duplex stability depends strongly on ionic conditions, and inside cells RNAs are exposed to both monovalent and multivalent ions. Despite recent advances, we do not have general methods to quantitatively account for the effects of monovalent and multivalent ions on RNA stability, and the thermodynamic parameters for secondary structure prediction have only been derived at 1M [Na+]. Here, by mechanically unfolding and folding a 20 bp RNA hairpin using optical tweezers, we study the RNA thermodynamics and kinetics at different monovalent and mixed monovalent/Mg2+ salt conditions. We measure the unfolding and folding rupture forces and apply Kramers theory to extract accurate information about the hairpin free energy landscape under tension at a wide range of ionic conditions. We obtain non-specific corrections for the free energy of formation of the RNA hairpin and measure how the distance of the transition state to the folded state changes with force and ionic strength. We experimentally validate the Tightly Bound Ion model and obtain values for the persistence length of ssRNA. Finally, we test the approximate rule by which the non-specific binding affinity of divalent cations at a given concentration is equivalent to that of monovalent cations taken at 100-fold concentration for small molecular constructs. PMID:22492710

Fluorescence imaging and dynamics of intracellular ionic concentrations in single living cells: application to pHi and Mgi variations

NASA Astrophysics Data System (ADS)

Viallet, Pierre M.; Yassine, Mohamed; Salmon, Jean-Marie; Vigo, Jean

1996-05-01

The intracellular concentration of ions such as H+, Hg2+, Ca2+ is known to monitor the activity of many intracellular enzymes. Furthermore these ions are considered as intracellular messengers involved in signal transducing. Moreover recent technological progresses gave rise to the feeling that accurate data are instantly accessible on microvolumes. So the determination of ionic intracellular concentrations has been achieved using fluorescent specific probes and different equipments (Microspectrofluorometer, Flow Cytometer, Numerical Image Analyzer with or without Confocal system), without taking care of the physico-chemical properties of the probe. Unfortunately fluorescent probes are supposed to fill up conflicting requirements in terms of ionic affinity, specificity, fluorescence quantum yield of the free and ion-bound probe, absence of fading and diffusibility out of the cell. Because most of the probes are not so specific than it is claimed, unexpected interactions may obscure the interpretation of results and even make it difficult to get an intracellular calibration curve. Such a situation generally precludes the use of the popular simplest methods of data acquisition and treatment. The scope of this presentation is to point out some underestimated difficulties, to discuss different ways for bypassing some of them and to rationale the use of Videomicrofluorometry.

Ionic liquid biodegradability depends on specific wastewater microbial consortia.

PubMed

Docherty, Kathryn M; Aiello, Steven W; Buehler, Barbara K; Jones, Stuart E; Szymczyna, Blair R; Walker, Katherine A

2015-10-01

Complete biodegradation of a newly-synthesized chemical in a wastewater treatment plant (WWTP) eliminates the potential for novel environmental pollutants. However, differences within- and between-WWTP microbial communities may alter expectations for biodegradation. WWTP communities can also serve as a source of unique consortia that, when enriched, can metabolize chemicals that tend to resist degradation, but are otherwise promising green alternatives. We tested the biodegradability of three ionic liquids (ILs): 1-octyl-3-methylpyridinium bromide (OMP), 1-butyl-3-methylpyridinium bromide (BMP) and 1-butyl-3-methylimidazolium chloride (BMIM). We performed tests using communities from two WWTPs at three time points. Site-specific and temporal variation both influenced community composition, which impacted the success of OMP biodegradability. Neither BMP nor BMIM degraded in any test, suggesting that these ILs are unlikely to be removed by traditional treatment. Following standard biodegradation assays, we enriched for three consortia that were capable of quickly degrading OMP, BMP and BMIM. Our results indicate WWTPs are not functionally redundant with regard to biodegradation of specific ionic liquids. However, consortia can be enriched to degrade chemicals that fail biodegradability assays. This information can be used to prepare pre-treatment procedures and prevent environmental release of novel pollutants. Copyright © 2015 Elsevier Ltd. All rights reserved.

Molecularly imprinted electrochemical sensing interface based on in-situ-polymerization of amino-functionalized ionic liquid for specific recognition of bovine serum albumin.

PubMed

Wang, Yanying; Han, Miao; Liu, Guishen; Hou, Xiaodong; Huang, Yina; Wu, Kangbing; Li, Chunya

2015-12-15

A molecularly imprinted polymer film was in situ polymerized on a carboxyl functionalized multi-walled carbon nanotubes modified glassy carbon electrode surface under room temperature. This technique provides a promising imprinting approach for protein in an aqueous solution using 3-(3-aminopropyl)-1-vinylimidazolium tetrafluoroborate ionic liquid as functional monomer, N, N'-methylenebisacrylamide as crossing linker, ammonium persulfate and N,N,N',N'-tetramethylethylenediamine as initiator, and bovine serum albumin (BSA) as template. The molecularly imprinted polymerized ionic liquid film shows enhanced accessibility, high specificity and sensitivity towards BSA. Electrochemical sensing performance of the imprinted sensor was thoroughly investigated using K3Fe[CN]6/K4Fe[CN]6 as electroactive probes. Under optimal conditions, the current difference before and after specific recognition of BSA was found linearly related to its concentration in the range from 1.50×10(-9) to 1.50×10(-6) mol L(-1). The detection limit was calculated to be 3.91×10(-10) mol L(-1) (S/N=3). The practical application of the imprinted sensor was demonstrated by determining BSA in liquid milk samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Electrophoretic deposition of multi-walled carbon nanotubes on porous anodic aluminum oxide using ionic liquid as a dispersing agent

NASA Astrophysics Data System (ADS)

Hekmat, F.; Sohrabi, B.; Rahmanifar, M. S.; Jalali, A.

2015-06-01

Multi-wall carbon nanotubes (MW-CNTs) have been arranged in nanochannels of anodic aluminum oxide template (AAO) by electrophoretic deposition (EPD) to make a vertically-aligned carbon nanotube (VA-CNT) based electrode. Well ordered AAO templates were prepared by a two-step anodizing process by applying a constant voltage of 45 V in oxalic acid solution. The stabilized CNTs in a water-soluble room temperature ionic liquid (1-methyl-3-octadecylimidazolium bromide), were deposited in the pores of AAO templates which were conductive by deposition of Ni nanoparticles in the bottom of pores. In order to obtain ideal results, different EPD parameters, such as concentration of MWCNTs and ionic liquid on stability of MWCNT suspensions, deposition time and voltage which are applied in EPD process and also optimal conditions for anodizing of template were investigated. The capacitive performance of prepared electrodes was analyzed by measuring the specific capacitance from cyclic voltammograms and the charge-discharge curves. A maximum value of 50 Fg-1 at the scan rate of 20 mV s-1was achieved for the specific capacitance.

Ionic liquids: solvents and sorbents in sample preparation.

PubMed

Clark, Kevin D; Emaus, Miranda N; Varona, Marcelino; Bowers, Ashley N; Anderson, Jared L

2018-01-01

The applications of ionic liquids (ILs) and IL-derived sorbents are rapidly expanding. By careful selection of the cation and anion components, the physicochemical properties of ILs can be altered to meet the requirements of specific applications. Reports of IL solvents possessing high selectivity for specific analytes are numerous and continue to motivate the development of new IL-based sample preparation methods that are faster, more selective, and environmentally benign compared to conventional organic solvents. The advantages of ILs have also been exploited in solid/polymer formats in which ordinarily nonspecific sorbents are functionalized with IL moieties in order to impart selectivity for an analyte or analyte class. Furthermore, new ILs that incorporate a paramagnetic component into the IL structure, known as magnetic ionic liquids (MILs), have emerged as useful solvents for bioanalytical applications. In this rapidly changing field, this Review focuses on the applications of ILs and IL-based sorbents in sample preparation with a special emphasis on liquid phase extraction techniques using ILs and MILs, IL-based solid-phase extraction, ILs in mass spectrometry, and biological applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ether- and Alcohol-Functionalized Task-Specific Ionic Liquids: Attractive Properties and Applications

PubMed Central

Tang, Shaokun; Baker, Gary A.; Zhao, Hua

2012-01-01

In recent years, the designer nature of ionic liquids (ILs) has driven their exploration and exploitation in countless fields among the physical and chemical sciences. A fair measure of the tremendous attention placed on these fluids has been attributed to their inherent designer nature. And yet, there are relatively few examples of reviews which emphasize this vital aspect in an exhaustive or meaningful way. In this critical review, we systematically survey the physicochemical properties of the collective library of ether- and alcohol-functionalized ILs, highlighting the impact of ionic structure on features such as viscosity, phase behavior/transitions, density, thermostability, electrochemical properties, and polarity (e.g., hydrophilicity, hydrogen bonding capability). In the latter portions of this review, we emphasize the attractive applications of these functionalized ILs across a range of disciplines, including their use as electrolytes or functional fluids for electrochemistry, extractions, biphasic systems, gas separations, carbon capture, carbohydrate dissolution (particularly, the (ligno)celluloses), polymer chemistry, antimicrobial and antielectrostatic agents, organic synthesis, biomolecular stabilization and activation, and nanoscience. Finally, this review discusses anion-functionalized ILs, including sulfur- and oxygen-functionalized analogs, as well as choline-based deep eutectic solvents (DESs), an emerging class of fluids which can be sensibly categorized as semi-molecular cousins to the IL. Finally, the toxicity and biodegradability of ether- and alcohol-functionalized ILs are discussed and cautiously evaluated in light of recent reports. By carefully summarizing literature examples on the properties and applications of oxy-functional designer ILs up till now, it is our intent that this review offer a barometer for gauging future advances in the field as well as a trigger to spur further contemplation of these seemingly inexhaustible and—relative to their potential—virtually untouched fluids. It is abundantly clear that these remarkable fluidic materials are here to stay, just as certain design rules are slowly beginning to emerge. However, in fairness, serendipity also still plays an undeniable role, highlighting the need for both expanded in silico studies and a beacon to attract bright, young researchers to the field. PMID:22456483

An experimental study on PEO polymer electrolyte based all-solid-state supercapacitor

NASA Astrophysics Data System (ADS)

Yijing, Yin

Supercapacitors are one of the most important electrochemical energy storage and conversion devices, however low ionic conductivity of solid state polymer electrolytes and the poor accessibility of the ions to the active sites in the porous electrode will cause low performance for all-solid-state supercapacitors and will limit their application. The objective of the dissertation is to improve the performance of all-solid-state supercapactor by improving electrolyte conductivity and solving accessibility problem of the ions to the active sites. The low ionic conductivity (10-8 S/cm) of poly(ethylene oxide) (PEO) limits its application as an electrolyte. Since PEO is a semicrystal polymer and the ion conduction take place mainly in the amorphous regions of the PEO/Lithium salt complex, improvements in the percentage of amorphous phase in PEO or increasing the charge carrier concentration and mobility could increase the ionic conductivity of PEO electrolyte. Hot pressing along with the additions of different lithium salts, inorganic fillers and plasticizers were applied to improve the ionic conductivity of PEO polymer electrolytes. Four electrode methods were used to evaluate the conductivity of PEO based polymer electrolytes. Results show that adding certain lithium salts, inorganic fillers, and plasticizers could improve the ionic conductivity of PEO electrolytes up 10-4 S/cm. Further hot pressing treatment could improve the ionic conductivity of PEO electrolytes up to 10-3 S/cm. The conductivity improvement after hot pressing treatment is elucidated as that the spherulite crystal phase is convert into the fringed micelle crystal phase or the amorphous phase of PEO electrolytes. PEO electrolytes were added into active carbon as a binder and an ion conductor, so as to provide electrodes with not only ion conduction, but also the accessibility of ion to the active sites of electrodes. The NaI/I 2 mediator was added to improve the conductivity of PEO electrolyte and provide pseudocapacitance for all-solid-state supercapacitors. Impedance, cyclic voltammetry, and gavalnostatic charge/discharge measurements were conducted to evaluate the electrochemical performance of PEO polymer electrolytes based all-solid-state supercapacitors. Results demonstrate that the conductivity of PEO electrolyte could be improved to 0.1 S/cm with a mediator concentration of 50wt%. A high conductivity in the PEO electrolyte with mediator is an indication of a high electron exchange rate between the mediator and mediator. The high electron exchange rates at mediator carbon interface and between mediator and mediator are essential in order to obtain a high response rate and high power. This automatically solves the accessibility problem. With the addition of NaI/I2 mediator, the specific capacitance increased more than 30 folds, specific power increased almost 20 folds, and specific energy increased around 10 folds. Further addition of filler to the electrodes along with the mediator could double the specific capacitor and specific power of the all-solid-state supercapacitor. The stability of the corresponded supercapacitor is good within 2000 cycles.

Preliminary evidence of reduced brain network activation in patients with post-traumatic migraine following concussion.

PubMed

Kontos, Anthony P; Reches, Amit; Elbin, R J; Dickman, Dalia; Laufer, Ilan; Geva, Amir B; Shacham, Galit; DeWolf, Ryan; Collins, Michael W

2016-06-01

Post-traumatic migraine (PTM) (i.e., headache, nausea, light and/or noise sensitivity) is an emerging risk factor for prolonged recovery following concussion. Concussions and migraine share similar pathophysiology characterized by specific ionic imbalances in the brain. Given these similarities, patients with PTM following concussion may exhibit distinct electrophysiological patterns, although researchers have yet to examine the electrophysiological brain activation in patients with PTM following concussion. A novel approach that may help differentiate brain activation in patients with and without PTM is brain network activation (BNA) analysis. BNA involves an algorithmic analysis applied to multichannel EEG-ERP data that provides a network map of cortical activity and quantitative data during specific tasks. A prospective, repeated measures design was used to evaluate BNA (during Go/NoGo task), EEG-ERP, cognitive performance, and concussion related symptoms at 1, 2, 3, and 4 weeks post-injury intervals among athletes with a medically diagnosed concussion with PTM (n = 15) and without (NO-PTM) (n = 22); and age, sex, and concussion history matched controls without concussion (CONTROL) (n = 20). Participants with PTM had significantly reduced BNA compared to NO-PTM and CONTROLS for Go and NoGo components at 3 weeks and for NoGo component at 4 weeks post-injury. The PTM group also demonstrated a more prominent deviation of network activity compared to the other two groups over a longer period of time. The composite BNA algorithm may be a more sensitive measure of electrophysiological change in the brain that can augment established cognitive assessment tools for detecting impairment in individuals with PTM.

Safe lithium-ion battery with ionic liquid-based electrolyte for hybrid electric vehicles

NASA Astrophysics Data System (ADS)

Damen, Libero; Lazzari, Mariachiara; Mastragostino, Marina

2011-10-01

A lithium-ion battery featuring graphite anode, LiFePO4-C cathode and an innovative, safe, ionic liquid-based electrolyte, was assembled and characterized in terms of specific energy and power after the USABC-DOE protocol for power-assist hybrid electric vehicle (HEV) application. The test results show that the battery surpasses the energy and power goals stated by USABC-DOE and, hence, this safe lithium-ion battery should be suitable for application in the evolving HEV market.

The Hydrogen Abstraction from A Diamond(111) Surface in A Uniform Electric Field

NASA Technical Reports Server (NTRS)

Ricca, Alessandra; Bauschlicher, Charles W., Jr.; Kang, Jeung Ku.; Musgrave, Charles B.; Arnold, James O. (Technical Monitor)

1998-01-01

Bond breaking in a strong electric field is shown to arise from a crossing of the ionic and covalent asymptotes. The specific example of hydrogen abstraction from a diamond(111) surface is studied using a cluster model. The addition of nearby atoms in both the parallel and perpendicular direction to the electric field are found to have an effect. It is also shown that the barrier is not only related to the position of the ionic and covalent asymptotes.

Simultaneous improvement in ionic conductivity and flexibility of solid polymer electrolytes for thin film lithium ion batteries

NASA Astrophysics Data System (ADS)

Ji, Jianying

Solid polymer electrolytes (SPEs) provide advantages over liquid electrolytes in terms of safety, reliability, less temperature sensitive, and simplicity of design. With the use of a SPE in lithium batteries, high specific energy and specific power, safe operation, flexibility in packaging, and low cost of fabrication can be expected. However, after 30 years, SPEs have rarely found commercial success due to the low ionic conductivity and/or insufficient mechanical properties, both of which are related to the movement of the polymer chains. Many physical/chemical methods have been exploited to simultaneously create enhancement in ionic conductivity and mechanical properties, and some suggested ways have shown promise. However, the complex strategies have always introduced other challenge issues and incurred extra costs for manufacturing. In such a context, the development of dry solid state electrolytes is the central challenge to be faced worldwide. This thesis deals with the approaches to improving ionic conductivity and mechanical properties simultaneously. The method is to apply two kinds of controllable organic fillers: copolymer and protein. Our work revealed that the commercial available copolymer, poly (ethylene oxide)- block-polyethylene (PEO-b-PE), possesses a capability for enhancing the multiple performances of poly(ethylene oxide)(PEO)-based polymer electrolyte. And the effects of composition and molecular weight of the copolymers on performance of the resulting SPEs were examined. It was found that increasing the PE block percentage in the copolymer resulted in a significant increase in both ionic conductivity and mechanical properties, while increasing the molecular weight of the copolymer resulted in better mechanical properties, and an identical ionic conductivity. A rubber-like, soy protein-based SPE (s-SPE)was obtained by employing soy protein isolate (SPI), a soy product usually used as rigid fillers for enhancing mechanical properties of polymers, blended with poly(ethylene oxide)(PEO). The results indicated that the s-SPE with 55 wt% of SPI possesses a fully amorphous uniform structure having low Tg, in contrast with crystalline PEO-based SPE having discernable Tg and Tm. The conductivity and elasticity are both significantly improved with SPI involvement. Remarkably, this film has been elongated up to 100% without loss of ionic conductivity and 700% without mechanical damage.

Thermally-responsive, nonflammable phosphonium ionic liquid electrolytes for lithium metal batteries: operating at 100 degrees celsius.

PubMed

Lin, X; Kavian, R; Lu, Y; Hu, Q; Shao-Horn, Y; Grinstaff, M W

2015-11-13

Rechargeable batteries such as Li ion/Li metal batteries are widely used in the electronics market but the chemical instability of the electrolyte limits their use in more demanding environmental conditions such as in automotive, oil exploration, or mining applications. In this study, a series of alkyl phosphonium ionic liquid electrolyte are described with high thermal stability and solubility for LiTFSI. A lithium metal battery (LMB) containing a tailored phosphonium ionic liquid/LiTFSI electrolyte operates at 100 °C with good specific capacities and cycling stability. Substantial capacity is maintained during 70 cycles or 30 days. Instant on-off battery operation is realized via the significant temperature dependence of the electrolyte material, demonstrating the robustness and potential for use at high temperature.

High-performance supercapacitors based on poly(ionic liquid)-modified graphene electrodes.

PubMed

Kim, Tae Young; Lee, Hyun Wook; Stoller, Meryl; Dreyer, Daniel R; Bielawski, Christopher W; Ruoff, Rodney S; Suh, Kwang S

2011-01-25

We report a high-performance supercapacitor incorporating a poly(ionic liquid)-modified reduced graphene oxide (PIL:RG-O) electrode and an ionic liquid (IL) electrolyte (specifically, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide or EMIM-NTf(2)). PIL:RG-O provides enhanced compatibility with the IL electrolyte, thereby increasing the effective electrode surface area accessible to electrolyte ions. The supercapacitor assembled with PIL:RG-O electrode and EMIM-NTf(2) electrolyte showed a stable electrochemical response up to 3.5 V operating voltage and was capable of yielding a maximum energy density of 6.5 W·h/kg with a power density of 2.4 kW/kg. These results demonstrate the potential of the PIL:RG-O material as an electrode in high-performance supercapacitors.

Molecular and ionic mimicry and the transport of toxic metals

PubMed Central

Bridges, Christy C.; Zalups, Rudolfs K.

2008-01-01

Despite many scientific advances, human exposure to, and intoxication by, toxic metal species continues to occur. Surprisingly, little is understood about the mechanisms by which certain metals and metal-containing species gain entry into target cells. Since there do not appear to be transporters designed specifically for the entry of most toxic metal species into mammalian cells, it has been postulated that some of these metals gain entry into target cells, through the mechanisms of ionic and/or molecular mimicry, at the site of transporters of essential elements and/or molecules. The primary purpose of this review is to discuss the transport of selective toxic metals in target organs and provide evidence supporting a role of ionic and/or molecular mimicry. In the context of this review, molecular mimicry refers to the ability of a metal ion to bond to an endogenous organic molecule to form an organic metal species that acts as a functional or structural mimic of essential molecules at the sites of transporters of those molecules. Ionic mimicry refers to the ability of a cationic form of a toxic metal to mimic an essential element or cationic species of an element at the site of a transporter of that element. Molecular and ionic mimics can also be sub-classified as structural or functional mimics. This review will present the established and putative roles of molecular and ionic mimicry in the transport of mercury, cadmium, lead, arsenic, selenium, and selected oxyanions in target organs and tissues. PMID:15845419

Explicit role of ionic strength in retention behavior of polystyrene latex particles in sedimentation field-flow fractionation: Slip boundary model.

PubMed

Rah, Kyunil; Han, Sujeong; Choi, Jaeyeong; Eum, Chul Hun; Lee, Seungho

2017-12-15

We investigate an explicit role of the ionic strength in the retention behaviors of polystyrene (PS) latex particles in sedimentation field-flow fractionation (SdFFF) by hinging upon the retention theory recently developed [1] asR=(R o +v b * )/(1+v b * ). Here R is an experimental retention ratio, and R o is the analytical expression of the standard retention theory based on the parabolic flow velocity. The reduced boundary velocityv b * is expressed in terms of the ionic strength I of the carrier liquid as v b * =v b,o * /(1+εI), where v b,o * =0.070and ε=60 mM -1 for all the PS latex systems under investigation. We then apply this to study the explicit ionic strength effect on the retention behaviors of PS beads of 200, 300, 400, and 500nm, respectively. As a primary result, the strong dependence of the retention ratio on the ionic strength can be quantitatively accounted for in an excellent accuracy: The slip effect at the channel surface is significant, particularly when I≲0.5mM, without showing any distinguishable dependence on the specific additives to control I, such as FL-70, SDS, NaNO 3 , and NaN 3 . Based on the present study, we put forward an experimental means to estimate the ionic strength of an aqueous solution using an FFF technique. Copyright © 2017. Published by Elsevier B.V.

Molecular and ionic mimicry and the transport of toxic metals

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

Bridges, Christy C.; Zalups, Rudolfs K.

Despite many scientific advances, human exposure to, and intoxication by, toxic metal species continues to occur. Surprisingly, little is understood about the mechanisms by which certain metals and metal-containing species gain entry into target cells. Since there do not appear to be transporters designed specifically for the entry of most toxic metal species into mammalian cells, it has been postulated that some of these metals gain entry into target cells, through the mechanisms of ionic and/or molecular mimicry, at the site of transporters of essential elements and/or molecules. The primary purpose of this review is to discuss the transport ofmore » selective toxic metals in target organs and provide evidence supporting a role of ionic and/or molecular mimicry. In the context of this review, molecular mimicry refers to the ability of a metal ion to bond to an endogenous organic molecule to form an organic metal species that acts as a functional or structural mimic of essential molecules at the sites of transporters of those molecules. Ionic mimicry refers to the ability of a cationic form of a toxic metal to mimic an essential element or cationic species of an element at the site of a transporter of that element. Molecular and ionic mimics can also be sub-classified as structural or functional mimics. This review will present the established and putative roles of molecular and ionic mimicry in the transport of mercury, cadmium, lead, arsenic, selenium, and selected oxyanions in target organs and tissues.« less

Dissection of specific binding of HIV-1 Gag to the 'packaging signal' in viral RNA.

PubMed

Comas-Garcia, Mauricio; Datta, Siddhartha Ak; Baker, Laura; Varma, Rajat; Gudla, Prabhakar R; Rein, Alan

2017-07-20

Selective packaging of HIV-1 genomic RNA (gRNA) requires the presence of a cis -acting RNA element called the 'packaging signal' (Ψ). However, the mechanism by which Ψ promotes selective packaging of the gRNA is not well understood. We used fluorescence correlation spectroscopy and quenching data to monitor the binding of recombinant HIV-1 Gag protein to Cy5-tagged 190-base RNAs. At physiological ionic strength, Gag binds with very similar, nanomolar affinities to both Ψ-containing and control RNAs. We challenged these interactions by adding excess competing tRNA; introducing mutations in Gag; or raising the ionic strength. These modifications all revealed high specificity for Ψ. This specificity is evidently obscured in physiological salt by non-specific, predominantly electrostatic interactions. This nonspecific activity was attenuated by mutations in the MA, CA, and NC domains, including CA mutations disrupting Gag-Gag interaction. We propose that gRNA is selectively packaged because binding to Ψ nucleates virion assembly with particular efficiency.

Specific binding of (/sup 3/H-Tyr8)physalaemin to rat submaxillary gland substance P receptor

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

Bahouth, S.W.; Lazaro, D.M.; Brundish, D.E.

1985-01-01

(/sup 3/H)Physalaemin ((/sup 3/H)PHY) binds to a single class of noninteracting sites on rat submaxillary gland membranes suspended in high ionic strength media with a KD of 2.7 nM, a Bmax of 240 fmol/mg of protein, and low nonspecific binding. The relative potencies of substance P (SP) and its fragments in competing with (/sup 3/H)PHY correlate with their relative salivation potencies. This indicates that (/sup 3/H)PHY interacts with a physiologically relevant SP receptor. In low ionic strength media, the KD of (/sup 3/H)PHY does not change, but SP and some of its fragments are more potent than PHY in competingmore » with (/sup 3/H) PHY. Computer-assisted analysis of (/sup 3/H)PHY and (/sup 3/H)SP binding in high and low ionic strength media demonstrated that both peptides are equipotent in high ionic strength but that the affinity of SP increases by 70-fold in low ionic strength. The SP fragments that contain a basic residue in positions 1 and/or 3 also display an increased affinity in low ionic strength. These findings document that (/sup 3/H)PHY binding in high ionic strength (mu . 0.6) accurately reflects the pharmacological potencies of agonists on the SP-P receptor. The binding of (/sup 3/H)PHY, like that of (/sup 3/H)SP, increases by the addition of divalent cations (Mg2+ greater than Ca2+ greater than Mn2+). Guanine nucleotides decrease (/sup 3/H)PHY binding by decreasing the Bmax to the same level (160 fmol/mg of protein), in the presence or absence of Mg2+.« less

Conductivity relaxation and charge transport of trihexyl tetradecyl phosphonium dicyanamide ionic liquid by broadband dielectric spectroscopy

NASA Astrophysics Data System (ADS)

Thasneema K., K.; Thayyil, M. Shahin; Krishna Kumar N., S.; Govindaraj, G.; Saheer, V. C.

2018-04-01

Usually ionic liquids consists of a large organic cation with low symmetry such as imidazolium, pyridinium, quaternary ammonium or phosponium etc combined with enormously wide range of inorganic or organic symmetric anion with melting point below 100. Ionic liquids existing in an extremely large number of possible ion pair combinations. It offers a very wide range of thermo physical properties led to the concept of designer solvents for specific applications. Due to the features of high chemical and thermal stability, low vapor pressure non flammability high ionic conductivity, and they show a good solvent ability towards a great variety of organic or inorganic compounds, ionic liquids have a widespread use in many areas such as batteries, fuel cell, solar cells, super capacitors etc. The main focus of this work is the study of molecular dynamics and conductivity relaxation of amorphous Trihexyl tetradecyl phosphonium dicyanamide ([P14,6,6,6][N(CN)2]) ionic liquid which is proved as a better electrolyte in super capacitors, over a wide frequency 10-2 Hz to 107 Hz and the temperature range between 123k and 265 k by means of Broadband Dielectric Spectroscopy. We observe alpha conductivity relaxation and secondary relaxation above and below Glass Transition Temperature. The experimental results were analyzed using electric modulus representation. The analysis emphasis the inter molecular interaction and the nature of glass forming system, whether it is fragile or strong system. The ionic liquid shows a fragile behavior and the fragility index m=123.59. TGA result of the sample exhibit a good resistance to thermal decomposition, up to 300°C.

Improved Activity of a Thermophilic Cellulase, Cel5A, from Thermotoga maritima on Ionic Liquid Pretreated Switchgrass

PubMed Central

Chen, Zhiwei; Pereira, Jose H.; Liu, Hanbin; Tran, Huu M.; Hsu, Nathan S. Y.; Dibble, Dean; Singh, Seema; Adams, Paul D.; Sapra, Rajat; Hadi, Masood Z.; Simmons, Blake A.; Sale, Kenneth L.

2013-01-01

Ionic liquid pretreatment of biomass has been shown to greatly reduce the recalcitrance of lignocellulosic biomass, resulting in improved sugar yields after enzymatic saccharification. However, even under these improved saccharification conditions the cost of enzymes still represents a significant proportion of the total cost of producing sugars and ultimately fuels from lignocellulosic biomass. Much of the high cost of enzymes is due to the low catalytic efficiency and stability of lignocellulolytic enzymes, especially cellulases, under conditions that include high temperatures and the presence of residual pretreatment chemicals, such as acids, organic solvents, bases, or ionic liquids. Improving the efficiency of the saccharification process on ionic liquid pretreated biomass will facilitate reduced enzyme loading and cost. Thermophilic cellulases have been shown to be stable and active in ionic liquids but their activity is typically at lower levels. Cel5A_Tma, a thermophilic endoglucanase from Thermotoga maritima, is highly active on cellulosic substrates and is stable in ionic liquid environments. Here, our motivation was to engineer mutants of Cel5A_Tma with higher activity on 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]) pretreated biomass. We developed a robotic platform to screen a random mutagenesis library of Cel5A_Tma. Twelve mutants with 25–42% improvement in specific activity on carboxymethyl cellulose and up to 30% improvement on ionic-liquid pretreated switchgrass were successfully isolated and characterized from a library of twenty thousand variants. Interestingly, most of the mutations in the improved variants are located distally to the active site on the protein surface and are not directly involved with substrate binding. PMID:24244549

Improved activity of a thermophilic cellulase, Cel5A, from Thermotoga maritima on ionic liquid pretreated switchgrass.

PubMed

Chen, Zhiwei; Pereira, Jose H; Liu, Hanbin; Tran, Huu M; Hsu, Nathan S Y; Dibble, Dean; Singh, Seema; Adams, Paul D; Sapra, Rajat; Hadi, Masood Z; Simmons, Blake A; Sale, Kenneth L

2013-01-01

Ionic liquid pretreatment of biomass has been shown to greatly reduce the recalcitrance of lignocellulosic biomass, resulting in improved sugar yields after enzymatic saccharification. However, even under these improved saccharification conditions the cost of enzymes still represents a significant proportion of the total cost of producing sugars and ultimately fuels from lignocellulosic biomass. Much of the high cost of enzymes is due to the low catalytic efficiency and stability of lignocellulolytic enzymes, especially cellulases, under conditions that include high temperatures and the presence of residual pretreatment chemicals, such as acids, organic solvents, bases, or ionic liquids. Improving the efficiency of the saccharification process on ionic liquid pretreated biomass will facilitate reduced enzyme loading and cost. Thermophilic cellulases have been shown to be stable and active in ionic liquids but their activity is typically at lower levels. Cel5A_Tma, a thermophilic endoglucanase from Thermotoga maritima, is highly active on cellulosic substrates and is stable in ionic liquid environments. Here, our motivation was to engineer mutants of Cel5A_Tma with higher activity on 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]) pretreated biomass. We developed a robotic platform to screen a random mutagenesis library of Cel5A_Tma. Twelve mutants with 25-42% improvement in specific activity on carboxymethyl cellulose and up to 30% improvement on ionic-liquid pretreated switchgrass were successfully isolated and characterized from a library of twenty thousand variants. Interestingly, most of the mutations in the improved variants are located distally to the active site on the protein surface and are not directly involved with substrate binding.

Ionic Liquids to Replace Hydrazine

NASA Technical Reports Server (NTRS)

Koelfgen, Syri; Sims, Joe; Forton, Melissa; Allan, Barry; Rogers, Robin; Shamshina, Julia

2011-01-01

A method for developing safe, easy-to-handle propellants has been developed based upon ionic liquids (ILs) or their eutectic mixtures. An IL is a binary combination of a typically organic cation and anion, which generally produces an ionic salt with a melting point below 100 deg C. Many ILs have melting points near, or even below, room temperature (room temperature ionic liquids, RTILs). More importantly, a number of ILs have a positive enthalpy of formation. This means the thermal energy released during decomposition reactions makes energetic ILs ideal for use as propellants. In this specific work, to date, a baseline set of energetic ILs has been identified, synthesized, and characterized. Many of the ILs in this set have excellent performance potential in their own right. In all, ten ILs were characterized for their enthalpy of formation, density, melting point, glass transition point (if applicable), and decomposition temperature. Enthalpy of formation was measured using a microcalorimeter designed specifically to test milligram amounts of energetic materials. Of the ten ILs characterized, five offer higher Isp performance than hydrazine, ranging between 10 and 113 seconds higher than the state-of-the-art propellant. To achieve this level of performance, the energetic cations 4- amino-l,2,4-triazolium and 3-amino-1,2,4-triazolium were paired with various anions in the nitrate, dicyanamide, chloride, and 3-nitro-l,2,4-triazole families. Protonation, alkylation, and butylation synthesis routes were used for creation of the different salts.

Dissecting ion-specific dielectric spectra of sodium-halide solutions into solvation water and ionic contributions.

PubMed

Rinne, Klaus F; Gekle, Stephan; Netz, Roland R

2014-12-07

Using extensive equilibrium molecular dynamics simulations we determine the dielectric spectra of aqueous solutions of NaF, NaCl, NaBr, and NaI. The ion-specific and concentration-dependent shifts of the static dielectric constants and the dielectric relaxation times match experimental results very well, which serves as a validation of the classical and non-polarizable ionic force fields used. The purely ionic contribution to the dielectric response is negligible, but determines the conductivity of the salt solutions. The ion-water cross correlation contribution is negative and reduces the total dielectric response by about 5%-10% for 1 M solutions. The dominating water dielectric response is decomposed into different water solvation shells and ion-pair configurations, by this the spectral blue shift and the dielectric decrement of salt solutions with increasing salt concentration is demonstrated to be primarily caused by first-solvation shell water. With rising salt concentration the simulated spectra show more pronounced deviations from a single-Debye form and can be well described by a Cole-Cole fit, in quantitative agreement with experiments. Our spectral decomposition into ionic and different water solvation shell contributions does not render the individual contributions more Debye-like, this suggests the non-Debye-like character of the dielectric spectra of salt solutions not to be due to the superposition of different elementary relaxation processes with different relaxation times. Rather, the non-Debye-like character is likely to be an inherent spectral signature of solvation water around ions.

Effects of ammonium-based ionic liquids and 2,4-dichlorophenol on the phospholipid fatty acid composition of zebrafish embryos.

PubMed

Piotrowska, Aleksandra; Syguda, Anna; Wyrwas, Bogdan; Chrzanowski, Lukasz; Luckenbach, Till; Heipieper, Hermann J

2018-01-01

Ionic liquids consisting of a combination of herbicidal anions with a quaternary ammonium cation act as efficient herbicides, which are under consideration to be used in the agriculture. In the present study, we used embryos of the zebrafish (Danio rerio) as a model to assess the toxic potential of ammonium-based ionic liquids for aquatic organisms. As we assumed interference of the partially hydrophobic ionic liquid cation with lipids, we investigated the adaptation response in the lipid composition of the zebrafish embryos, triggered by the ionic compound. Therefore, the impact of ammonium-based ionic liquids with different lengths of the alkyl chain ([C6,C6,C1,C1N][Br], [C8,C8,C1,C1N][Br]) on the phospholipid fatty acid (PLFA) profile of zebrafish embryos up to 72 hours post fertilization (hpf) was examined. Furthermore, the changes in the unsaturation index (UI) of PLFAs, as the sum parameter of membrane fluidity in eukaryotic cells, were presented. The PLFA's UI in the zebrafish embryos upon exposure to quaternary ammonium salts was compared to the UI of the embryos upon exposure to nonionic 2,4-dichlorophenol, which has a similar hydrophobicity but is structurally different to [C8,C8,C1,C1N][Br]. It was shown that for ammonium-based ionic liquid precursors non-specific mode of action occurs and the toxic effect on lipid composition of zebrafish embryos can be well predicted based on chemical properties, like hydrophobicity. Furthermore, the changes in PLFAs, expressed by the UI, can be useful to study toxic effects of organic contamination. However, for zebrafish embryos, after ionic liquids and 2,4-DCP exposure, the changes were observed at high lethal concentrations, which caused the incidence of lethality of 30 and 50% of a group of test animals.

Effects of ammonium-based ionic liquids and 2,4-dichlorophenol on the phospholipid fatty acid composition of zebrafish embryos

PubMed Central

Piotrowska, Aleksandra; Syguda, Anna; Wyrwas, Bogdan; Chrzanowski, Lukasz; Luckenbach, Till

2018-01-01

Ionic liquids consisting of a combination of herbicidal anions with a quaternary ammonium cation act as efficient herbicides, which are under consideration to be used in the agriculture. In the present study, we used embryos of the zebrafish (Danio rerio) as a model to assess the toxic potential of ammonium-based ionic liquids for aquatic organisms. As we assumed interference of the partially hydrophobic ionic liquid cation with lipids, we investigated the adaptation response in the lipid composition of the zebrafish embryos, triggered by the ionic compound. Therefore, the impact of ammonium-based ionic liquids with different lengths of the alkyl chain ([C6,C6,C1,C1N][Br], [C8,C8,C1,C1N][Br]) on the phospholipid fatty acid (PLFA) profile of zebrafish embryos up to 72 hours post fertilization (hpf) was examined. Furthermore, the changes in the unsaturation index (UI) of PLFAs, as the sum parameter of membrane fluidity in eukaryotic cells, were presented. The PLFA’s UI in the zebrafish embryos upon exposure to quaternary ammonium salts was compared to the UI of the embryos upon exposure to nonionic 2,4-dichlorophenol, which has a similar hydrophobicity but is structurally different to [C8,C8,C1,C1N][Br]. It was shown that for ammonium-based ionic liquid precursors non-specific mode of action occurs and the toxic effect on lipid composition of zebrafish embryos can be well predicted based on chemical properties, like hydrophobicity. Furthermore, the changes in PLFAs, expressed by the UI, can be useful to study toxic effects of organic contamination. However, for zebrafish embryos, after ionic liquids and 2,4-DCP exposure, the changes were observed at high lethal concentrations, which caused the incidence of lethality of 30 and 50% of a group of test animals. PMID:29342167

Modeling solubility, acid-base properties and activity coefficients of amoxicillin, ampicillin and (+)6-aminopenicillanic acid, in NaCl(aq) at different ionic strengths and temperatures.

PubMed

Crea, Francesco; Cucinotta, Daniela; De Stefano, Concetta; Milea, Demetrio; Sammartano, Silvio; Vianelli, Giuseppina

2012-11-20

The total solubility of three penicillin derivatives was determined, in pure water and NaCl aqueous solutions at different salt concentrations (from ∼0.15 to 1.0 mol L(-1) for ampicillin and amoxicillin, and from ∼0.05 to 2.0 mol L(-1) for (+)6-aminopenicillanic acid), using the shake-flask method for generating the saturated solutions, followed by potentiometric analysis. The knowledge of the pH of solubilization and of the protonation constants determined in the same experimental conditions, allowed us to calculate, by means of the mass balance equations, the solubility of the neutral species at different ionic strength values, to model its dependence on the salt concentration and to determine the corresponding values at infinite dilution. The salting parameter and the activity coefficients of the neutral species were calculated by the Setschenow equation. The protonation constants of ampicillin and amoxicillin, determined at different temperatures (from T=288.15 to 318.15K), from potentiometric and spectrophotometric measurements, were used to calculate, by means of the Van't Hoff equation, the temperature coefficients at different ionic strength values and the corresponding protonation entropies. The protonation enthalpies of the (+)6-aminopenicillanic acid were determined by isoperibol calorimetric titrations at T=298.15K and up to I=2.0 mol L(-1). The dependence of the protonation constants on ionic strength was modeled by means of the Debye-Hückel and SIT (Specific ion Interaction Theory) approaches, and the specific interaction parameters of the ionic species were determined. The hydrolysis of the β-lactam ring was studied by spectrophotometric and H NMR investigations as a function of pH, ionic strength and time. Potentiometric measurements carried out on the hydrolyzed (+)6-aminopenicillanic acid allowed us to highlight that the opened and the closed β-lactam forms of the (+)6-aminopenicillanic acid have quite different acid-base properties. An analysis of literature solubility, protonation constants, enthalpies and activity coefficients is reported too. Copyright © 2012 Elsevier B.V. All rights reserved.

Hybrid nanowire ion-to-electron transducers for integrated bioelectronic circuitry (Conference Presentation)

NASA Astrophysics Data System (ADS)

Carrad, Damon J.; Mostert, Bernard; Meredith, Paul; Micolich, Adam P.

2016-09-01

A key task in bioelectronics is the transduction between ionic/protonic signals and electronic signals at high fidelity. This is a considerable challenge since the two carrier types exhibit intrinsically different physics. We present our work on a new class of organic-inorganic transducing interface utilising semiconducting InAs and GaAs nanowires directly gated with a proton transporting hygroscopic polymer consisting of undoped polyethylene oxide (PEO) patterned to nanoscale dimensions by a newly developed electron-beam lithography process [1]. Remarkably, we find our undoped PEO polymer electrolyte gate dielectric [2] gives equivalent electrical performance to the more traditionally used LiClO4-doped PEO [3], with an ionic conductivity three orders of magnitude higher than previously reported for undoped PEO [4]. The observed behaviour is consistent with proton conduction in PEO. We attribute our undoped PEO-based devices' performance to the small external surface and high surface-to-volume ratio of both the nanowire conducting channel and patterned PEO dielectric in our devices, as well as the enhanced hydration afforded by device processing and atmospheric conditions. In addition to studying the basic transducing mechanisms, we also demonstrate high-fidelity ionic to electronic conversion of a.c. signals at frequencies up to 50 Hz. Moreover, by combining complementary n- and p-type transducers we demonstrate functional hybrid ionic-electronic circuits can achieve logic (NOT operation), and with some further engineering of the nanowire contacts, potentially also amplification. Our device structures have significant potential to be scaled towards realising integrated bioelectronic circuitry. [1] D.J. Carrad et al., Nano Letters 14, 94 (2014). [2] D.J. Carrad et al., Manuscript in preparation (2016). [3] S.H. Kim et al., Advanced Materials 25, 1822 (2013). [4] S.K. Fullerton-Shirey et al., Macromolecules 42, 2142 (2009).

Ionic Liquid Directed Mesoporous Carbon Nanoflakes as an Effiencient Electrode material

NASA Astrophysics Data System (ADS)

Kong, Lirong; Chen, Wei

2015-12-01

Supercapacitors are considered to be the most promising approach to meet the pressing requirements for energy storage devices. The electrode materials for supercapacitors have close relationship with their electrochemical properties and thus become the key point to improve their energy storage efficiency. Herein, by using poly (vinylidene fluoride-co-hexafluoropropylene) and ionic liquid as the dual templates, polyacrylonitrile as the carbon precursor, a flake-like carbon material was prepared by a direct carbonization method. In this method, poly (vinylidene fluoride-co-hexafluoropropylene) worked as the separator for the formation of isolated carbon flakes while aggregated ionic liquid worked as the pore template. The obtained carbon flakes exhibited a specific capacitance of 170 F/g at 0.1 A/g, a high energy density of 12.2 Wh/kg and a high power density of 5 kW/kg at the current of 10 A/g. It also maintained a high capacitance retention capability with almost no declination after 500 charge-discharge cycles. The ionic liquid directed method developed here also provided a new idea for the preparation of hierarchically porous carbon nanomaterials.

All-solid-state flexible supercapacitors based on papers coated with carbon nanotubes and ionic-liquid-based gel electrolytes.

PubMed

Kang, Yu Jin; Chung, Haegeun; Han, Chi-Hwan; Kim, Woong

2012-02-17

All-solid-state flexible supercapacitors were fabricated using carbon nanotubes (CNTs), regular office papers, and ionic-liquid-based gel electrolytes. Flexible electrodes were made by coating CNTs on office papers by a drop-dry method. The gel electrolyte was prepared by mixing fumed silica nanopowders with ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][NTf(2)]). This supercapacitor showed high power and energy performance as a solid-state flexible supercapacitor. The specific capacitance of the CNT electrodes was 135 F g(-1) at a current density of 2 A g(-1), when considering the mass of active materials only. The maximum power and energy density of the supercapacitors were 164 kW kg(-1) and 41 Wh kg(-1), respectively. Interestingly, the solid-state supercapacitor with the gel electrolyte showed comparable performance to the supercapacitors with ionic-liquid electrolyte. Moreover, the supercapacitor showed excellent stability and flexibility. The CNT/paper- and gel-based supercapacitors may hold great potential for low-cost and high-performance flexible energy storage applications.

All-solid-state flexible supercapacitors based on papers coated with carbon nanotubes and ionic-liquid-based gel electrolytes

NASA Astrophysics Data System (ADS)

Kang, Yu Jin; Chung, Haegeun; Han, Chi-Hwan; Kim, Woong

2012-02-01

All-solid-state flexible supercapacitors were fabricated using carbon nanotubes (CNTs), regular office papers, and ionic-liquid-based gel electrolytes. Flexible electrodes were made by coating CNTs on office papers by a drop-dry method. The gel electrolyte was prepared by mixing fumed silica nanopowders with ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][NTf2]). This supercapacitor showed high power and energy performance as a solid-state flexible supercapacitor. The specific capacitance of the CNT electrodes was 135 F g-1 at a current density of 2 A g-1, when considering the mass of active materials only. The maximum power and energy density of the supercapacitors were 164 kW kg-1 and 41 Wh kg-1, respectively. Interestingly, the solid-state supercapacitor with the gel electrolyte showed comparable performance to the supercapacitors with ionic-liquid electrolyte. Moreover, the supercapacitor showed excellent stability and flexibility. The CNT/paper- and gel-based supercapacitors may hold great potential for low-cost and high-performance flexible energy storage applications.

Thermo-Rheometric Studies of New Class Ionic Liquid Lubricants

NASA Astrophysics Data System (ADS)

Bakhtiyarov, Sayavur; Street, Kenneth; Scheiman, Daniel; van Dyke, Alan

2010-11-01

Due to their specific properties, such as small volatility, nonflammability, extreme thermal stability, low melting point, wide liquid range, and good miscibility with organic materials, ionic liquids attracted particular interest in various industrial processes. Recently, the unique properties of ionic liquids caught the attention of space tribologists. The traditional lubricating materials used in space have limited lifetimes in vacuum due to the catalytic degradation on metal surfaces, high vaporization at high temperatures, dewetting, and other disadvantages. The lubricants for the space applications must have vacuum stability, high viscosity index, low creep tendency, good elastohydrodynamic and boundary lubrication properties, radiation atomic oxygen resistance, optical or infrared transparency. Unfortunately, the properties such as heat flow, heat capacity, thermogravimetric weight loss, and non-linearity in the rheological behavior of the lubricants are not studied well for newly developed systems. These properties are crucial to analyzing thermodynamic and energy dissipative aspects of the lubrication process. In this paper we will present the rheological and heat and mass transfer measurements for the ionic liquid lubricants, their mixtures with and without additive.

Comparing Triflate and Hexafluorophosphate Anions of Ionic Liquids in Polymer Electrolytes for Supercapacitor Applications.

PubMed

Liew, Chiam-Wen; Ramesh, S

2014-05-21

Two different ionic liquid-based biopolymer electrolyte systems were prepared using a solution casting technique. Corn starch and lithium hexafluorophosphate (LiPF₆) were employed as polymer and salt, respectively. Additionally, two different counteranions of ionic liquids, viz. 1-butyl-3-methylimidazolium hexafluorophosphate (BmImPF₆) and 1-butyl-3-methylimidazolium trifluoromethanesulfonate (also known as 1-butyl-3-methylimidazolium triflate) (BmImTf) were used and studied in this present work. The maximum ionic conductivities of (1.47 ± 0.02) × 10 -4 and (3.21 ± 0.01) × 10 -4 S∙cm -1 were achieved with adulteration of 50 wt% of BmImPF₆ and 80 wt% of BmImTf, respectively at ambient temperature. Activated carbon-based electrodes were prepared and used in supercapacitor fabrication. Supercapacitors were then assembled using the most conducting polymer electrolyte from each system. The electrochemical properties of the supercapacitors were then analyzed. The supercapacitor containing the triflate-based biopolymer electrolyte depicted a higher specific capacitance with a wider electrochemical stability window compared to that of the hexafluorophosphate system.

Comparing Triflate and Hexafluorophosphate Anions of Ionic Liquids in Polymer Electrolytes for Supercapacitor Applications

PubMed Central

Liew, Chiam-Wen; Ramesh, S.

2014-01-01

Two different ionic liquid-based biopolymer electrolyte systems were prepared using a solution casting technique. Corn starch and lithium hexafluorophosphate (LiPF6) were employed as polymer and salt, respectively. Additionally, two different counteranions of ionic liquids, viz. 1-butyl-3-methylimidazolium hexafluorophosphate (BmImPF6) and 1-butyl-3-methylimidazolium trifluoromethanesulfonate (also known as 1-butyl-3-methylimidazolium triflate) (BmImTf) were used and studied in this present work. The maximum ionic conductivities of (1.47 ± 0.02) × 10−4 and (3.21 ± 0.01) × 10−4 S·cm−1 were achieved with adulteration of 50 wt% of BmImPF6 and 80 wt% of BmImTf, respectively at ambient temperature. Activated carbon-based electrodes were prepared and used in supercapacitor fabrication. Supercapacitors were then assembled using the most conducting polymer electrolyte from each system. The electrochemical properties of the supercapacitors were then analyzed. The supercapacitor containing the triflate-based biopolymer electrolyte depicted a higher specific capacitance with a wider electrochemical stability window compared to that of the hexafluorophosphate system. PMID:28788662

Ion Dynamics in a Mixed-Cation Alkoxy-Ammonium Ionic Liquid Electrolyte for Sodium Device Applications.

PubMed

Pope, Cameron R; Kar, Mega; MacFarlane, Douglas R; Armand, Michel; Forsyth, Maria; O'Dell, Luke A

2016-10-18

The ion dynamics in a novel sodium-containing room-temperature ionic liquid (IL) consisting of an ether-functionalised quaternary ammonium cation and bis(trifluoromethylsulfonyl)amide [NTf 2 ] anion with various concentrations of Na[NTf 2 ] have been characterised using differential scanning calorimetry, impedance spectroscopy, diffusometry and NMR relaxation measurements. The IL studied has been specifically designed to dissolve a relatively large concentration of Na[NTf 2 ] salt (over 2 mol kg -1 ) as this has been shown to improve ion transport and conductivity. Consistent with other studies, the measured ionic conductivity and diffusion coefficients show that the overall ionic mobility decreases with decreasing temperature and increasing salt content. NMR relaxation measurements provide evidence for correlated dynamics between the ether-functionalised ammonium and Na cations, possibly with the latter species acting as cross-links between multiple ammonium cations. Finally, preliminary cyclic voltammetry experiments show that this IL can undergo stable electrochemical cycling and could therefore be potentially useful as an electrolyte in a Na-based device. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Determination of the solubility parameter of ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate by inverse gas chromatography.

PubMed

Ma, Xiaohong; Wang, Qiang; Li, Xiaoping; Tang, Jun; Zhang, Zhengfang

2015-11-01

Thermodynamic properties of ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM] BF4) were determined via inverse gas chromatography (IGC). Two groups of solvents with different chemical natures and polarities were used to obtain information about [BMIM] BF4-solvent interactions. The specific retention volume, molar heat of sorption, weight fraction activity coefficient, Flory-Huggins interaction parameter as well as solubility parameter were also determined in a temperature range of 333 - 373 K. The results showed that the selected solvents n-C10 to n-C12, carbon tetrachloride, cyclohexane and toluene were poor solvents for [BMIM] BF4, while dichloromethane, acetone, chloroform, methyl acetate, ethanol and methanol were favorite solvents for [BMIM] BF4. In addition, the solubility parameter of [ BMIM] BF4 was determined as 23.39 (J/cm3)0.5 by the extrapolation at 298 K. The experiment proved that IGC was a simple and accurate method to obtain the thermodynamic properties of ionic liquids. This study could be used as a reference to the application and research of the ionic liquids.

Ionic polymer metal composites with nanoporous carbon electrodes

NASA Astrophysics Data System (ADS)

Palmre, Viljar; Brandell, Daniel; Mäeorg, Uno; Torop, Janno; Volobujeva, Olga; Punning, Andres; Johanson, Urmas; Aabloo, Alvo

2010-04-01

Ionic Polymer Metal Composites (IPMCs) are soft electroactive polymer materials that bend in response to the voltage stimulus (1 - 4 V). They can be used as actuators or sensors. In this paper, we introduce two new highly-porous carbon materials for assembling high specific area electrodes for IPMC actuators and compare their electromechanical performance with recently reported IPMCs based on RuO2 electrodes. We synthesize ionic liquid (Emi-Tf) actuators with either Carbide-Derived Carbon (CDC) (derived from TiC) or coconut shell based activated carbon electrodes. The carbon electrodes are applied onto ionic liquid-swollen Nafion membranes using the direct assembly process. Our results show that actuators assembled with CDC electrodes have the greatest peak-to-peak strain output, reaching up to 20.4 mɛ (equivalent to >2%) at a 2 V actuation signal, exceeding that of the RuO2 electrodes by more than 100%. The electrodes synthesized from TiC-derived carbon also revealed significantly higher maximum strain rate. The differences between the materials are discussed in terms of molecular interactions and mechanisms upon actuation in the different electrodes.

Computer Simulation Study of Graphene Oxide Supercapacitors: Charge Screening Mechanism.

PubMed

Park, Sang-Won; DeYoung, Andrew D; Dhumal, Nilesh R; Shim, Youngseon; Kim, Hyung J; Jung, YounJoon

2016-04-07

Graphene oxide supercapacitors in the parallel plate configuration are studied via molecular dynamics (MD) simulations. The full range of electrode oxidation from 0 to 100% is examined by oxidizing the graphene surface with hydroxyl groups. Two different electrolytes, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI(+)BF4(-)) as an ionic liquid and its 1.3 M solution in acetonitrile as an organic electrolyte, are considered. While the area-specific capacitance tends to decrease with increasing electrode oxidation for both electrolytes, its details show interesting differences between the organic electrolyte and ionic liquid, including the extent of decrease. For detailed insight into these differences, the screening mechanisms of electrode charges by electrolytes and their variations with electrode oxidation are analyzed with special attention paid to the aspects shared by and the contrasts between the organic electrolyte and ionic liquid.

ENZYMATIC POLYMERIZATION OF PHENOLS IN ROOM TEMPERATURE IONIC LIQUIDS

PubMed Central

Eker, Bilge; Zagorevski, Dmitri; Zhu, Guangyu; Linhardt, Robert J.; Dordick, Jonathan S.

2009-01-01

Soybean peroxidase (SBP) was used to catalyze the polymerization of phenols in room-temperature ionic liquids (RTILs). Phenolic polymers with number average molecular weights ranging from 1200 to 4100 D were obtained depending on the composition of the reaction medium and the nature of the phenol. Specifically, SBP was highly active in methylimidazolium-containing RTILs, including 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM(BF4)), and 1-butyl-3-methylpyridinium tetrafluoroborate (BMPy(BF4)) with the ionic liquid content as high as 90% (v/v); the balance being aqueous buffer. Gel permeation chromatography and MALDI-TOF analysis indicated that higher molecular weight polymers can be synthesized in the presence of higher RTIL concentrations, with selective control over polymer size achieved by varying the RTIL concentration. The resulting polyphenols exhibited high thermostability and possessed thermosetting properties. PMID:20161409

The effect of sulfate on selenate bioaccumulation in two freshwater primary producers: A duckweed (Lemna minor) and a green alga (Pseudokirchneriella subcapitata).

PubMed

Lo, Bonnie P; Elphick, James R; Bailey, Howard C; Baker, Josh A; Kennedy, Christopher J

2015-12-01

Predicting selenium bioaccumulation is complicated because site-specific conditions, including the ionic composition of water, affect the bioconcentration of inorganic selenium into the food web. Selenium tissue concentrations were measured in Lemna minor and Pseudokirchneriella subcapitata following exposure to selenate and sulfate. Selenium accumulation differed between species, and sulfate reduced selenium uptake in both species, indicating that ionic constituents, in particular sulfate, are important in modifying selenium uptake by primary producers. © 2015 SETAC.

Aloe vera Derived Activated High-Surface-Area Carbon for Flexible and High-Energy Supercapacitors.

PubMed

Karnan, M; Subramani, K; Sudhan, N; Ilayaraja, N; Sathish, M

2016-12-28

Materials which possess high specific capacitance in device configuration with low cost are essential for viable application in supercapacitors. Herein, a flexible high-energy supercapacitor device was fabricated using porous activated high-surface-area carbon derived from aloe leaf (Aloe vera) as a precursor. The A. vera derived activated carbon showed mesoporous nature with high specific surface area of ∼1890 m 2 /g. A high specific capacitance of 410 and 306 F/g was achieved in three-electrode and symmetric two-electrode system configurations in aqueous electrolyte, respectively. The fabricated all-solid-state device showed a high specific capacitance of 244 F/g with an energy density of 8.6 Wh/kg. In an ionic liquid electrolyte, the fabricated device showed a high specific capacitance of 126 F/g and a wide potential window up to 3 V, which results in a high energy density of 40 Wh/kg. Furthermore, it was observed that the activation temperature has significant role in the electrochemical performance, as the activated sample at 700 °C showed best activity than the samples activated at 600 and 800 °C. The electron microscopic images (FE-SEM and HR-TEM) confirmed the formation of pores by the chemical activation. A fabricated supercapacitor device in ionic liquid with 3 V could power up a red LED for 30 min upon charging for 20s. Also, it is shown that the operation voltage and capacitance of flexible all-solid-state symmetric supercapacitors fabricated using aloe-derived activated carbon could be easily tuned by series and parallel combinations. The performance of fabricated supercapacitor devices using A. vera derived activated carbon in all-solid-state and ionic liquid indicates their viable applications in flexible devices and energy storage.

Electrolytes and thermoregulation

NASA Technical Reports Server (NTRS)

Nielsen, B.; Greenleaf, J. E.

1977-01-01

The influence of ions on temperature is studied for cases where the changes in ionic concentrations are induced by direct infusion or injection of electrolyte solutions into the cerebral ventricles or into specific areas of brain tissue; intravenous infusion or injection; eating food or drinking solutions of different ionic composition; and heat or exercise dehydration. It is shown that introduction of Na(+) and Ca(++) into the cerebral ventricles or into the venous system affects temperature regulation. It appears that the specific action of these ions is different from their osmotic effects. It is unlikely that their action is localized to the thermoregulatory centers in the brain. The infusion experiments demonstrate that the changes in sodium balance occurring during exercise and heat stress are large enough to affect sweat gland function and vasomotor activity.

Forward genetics screen coupled with whole-genome resequencing identifies novel gene targets for improving heterologous enzyme production in Aspergillus niger

DOE PAGES

Reilly, Morgann C.; Kim, Joonhoon; Lynn, Jed; ...

2018-01-06

Plant biomass, once reduced to its composite sugars, can be converted to fuel substitutes. One means of overcoming the recalcitrance of lignocellulose is pretreatment followed by enzymatic hydrolysis. However, currently available commercial enzyme cocktails are inhibited in the presence of residual pretreatment chemicals. Recent studies have identified a number of cellulolytic enzymes from bacteria that are tolerant to pretreatment chemicals such as ionic liquids. The challenge now is generation of these enzymes in copious amounts, an arena where fungal organisms such as Aspergillus niger have proven efficient. Fungal host strains still need to be engineered to increase production titers ofmore » heterologous protein over native enzymes, which has been a difficult task. Here, we developed a forward genetics screen coupled with whole-genome resequencing to identify specific lesions responsible for a protein hyper-production phenotype in A. niger. As a result, this strategy successfully identified novel targets, including a low-affinity glucose transporter, MstC, whose deletion significantly improved secretion of recombinant proteins driven by a glucoamylase promoter.« less

Forward genetics screen coupled with whole-genome resequencing identifies novel gene targets for improving heterologous enzyme production in Aspergillus niger

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

Reilly, Morgann C.; Kim, Joonhoon; Lynn, Jed

Plant biomass, once reduced to its composite sugars, can be converted to fuel substitutes. One means of overcoming the recalcitrance of lignocellulose is pretreatment followed by enzymatic hydrolysis. However, currently available commercial enzyme cocktails are inhibited in the presence of residual pretreatment chemicals. Recent studies have identified a number of cellulolytic enzymes from bacteria that are tolerant to pretreatment chemicals such as ionic liquids. The challenge now is generation of these enzymes in copious amounts, an arena where fungal organisms such as Aspergillus niger have proven efficient. Fungal host strains still need to be engineered to increase production titers ofmore » heterologous protein over native enzymes, which has been a difficult task. Here, we developed a forward genetics screen coupled with whole-genome resequencing to identify specific lesions responsible for a protein hyper-production phenotype in A. niger. This strategy successfully identified novel targets, including a low-affinity glucose transporter, MstC, whose deletion significantly improved secretion of recombinant proteins driven by a glucoamylase promoter.« less

Forward genetics screen coupled with whole-genome resequencing identifies novel gene targets for improving heterologous enzyme production in Aspergillus niger

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

Reilly, Morgann C.; Kim, Joonhoon; Lynn, Jed

Plant biomass, once reduced to its composite sugars, can be converted to fuel substitutes. One means of overcoming the recalcitrance of lignocellulose is pretreatment followed by enzymatic hydrolysis. However, currently available commercial enzyme cocktails are inhibited in the presence of residual pretreatment chemicals. Recent studies have identified a number of cellulolytic enzymes from bacteria that are tolerant to pretreatment chemicals such as ionic liquids. The challenge now is generation of these enzymes in copious amounts, an arena where fungal organisms such as Aspergillus niger have proven efficient. Fungal host strains still need to be engineered to increase production titers ofmore » heterologous protein over native enzymes, which has been a difficult task. Here, we developed a forward genetics screen coupled with whole-genome resequencing to identify specific lesions responsible for a protein hyper-production phenotype in A. niger. As a result, this strategy successfully identified novel targets, including a low-affinity glucose transporter, MstC, whose deletion significantly improved secretion of recombinant proteins driven by a glucoamylase promoter.« less

Forward genetics screen coupled with whole-genome resequencing identifies novel gene targets for improving heterologous enzyme production in Aspergillus niger

DOE PAGES

Reilly, Morgann C.; Kim, Joonhoon; Lynn, Jed; ...

2018-01-06

Plant biomass, once reduced to its composite sugars, can be converted to fuel substitutes. One means of overcoming the recalcitrance of lignocellulose is pretreatment followed by enzymatic hydrolysis. However, currently available commercial enzyme cocktails are inhibited in the presence of residual pretreatment chemicals. Recent studies have identified a number of cellulolytic enzymes from bacteria that are tolerant to pretreatment chemicals such as ionic liquids. The challenge now is generation of these enzymes in copious amounts, an arena where fungal organisms such as Aspergillus niger have proven efficient. Fungal host strains still need to be engineered to increase production titers ofmore » heterologous protein over native enzymes, which has been a difficult task. Here, we developed a forward genetics screen coupled with whole-genome resequencing to identify specific lesions responsible for a protein hyper-production phenotype in A. niger. This strategy successfully identified novel targets, including a low-affinity glucose transporter, MstC, whose deletion significantly improved secretion of recombinant proteins driven by a glucoamylase promoter.« less

Poly(vinylidene fluoride-hexafluoropropylene) polymer electrolyte for paper-based and flexible battery applications

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

Aliahmad, Nojan; Shrestha, Sudhir; Varahramyan, Kody

2016-06-15

Paper-based batteries represent a new frontier in battery technology. However, low-flexibility and poor ionic conductivity of solid electrolytes have been major impediments in achieving practical mechanically flexible batteries. This work discuss new highly ionic conductive polymer gel electrolytes for paper-based battery applications. In this paper, we present a poly(vinylidene fluoride-hexafluoropropylene) (PVDH-HFP) porous membrane electrolyte enhanced with lithium bis(trifluoromethane sulphone)imide (LiTFSI) and lithium aluminum titanium phosphate (LATP), with an ionic conductivity of 2.1 × 10{sup −3} S cm{sup −1}. Combining ceramic (LATP) with the gel structure of PVDF-HFP and LiTFSI ionic liquid harnesses benefits of ceramic and gel electrolytes in providingmore » flexible electrolytes with a high ionic conductivity. In a flexibility test experiment, bending the polymer electrolyte at 90° for 20 times resulted in 14% decrease in ionic conductivity. Efforts to further improving the flexibility of the presented electrolyte are ongoing. Using this electrolyte, full-cell batteries with lithium titanium oxide (LTO) and lithium cobalt oxide (LCO) electrodes and (i) standard metallic current collectors and (ii) paper-based current collectors were fabricated and tested. The achieved specific capacities were (i) 123 mAh g{sup −1} for standard metallic current collectors and (ii) 99.5 mAh g{sup −1} for paper-based current collectors. Thus, the presented electrolyte has potential to become a viable candidate in paper-based and flexible battery applications. Fabrication methods, experimental procedures, and test results for the polymer gel electrolyte and batteries are presented and discussed.« less

Poly(vinylidene fluoride-hexafluoropropylene) polymer electrolyte for paper-based and flexible battery applications

NASA Astrophysics Data System (ADS)

Aliahmad, Nojan; Shrestha, Sudhir; Varahramyan, Kody; Agarwal, Mangilal

2016-06-01

Paper-based batteries represent a new frontier in battery technology. However, low-flexibility and poor ionic conductivity of solid electrolytes have been major impediments in achieving practical mechanically flexible batteries. This work discuss new highly ionic conductive polymer gel electrolytes for paper-based battery applications. In this paper, we present a poly(vinylidene fluoride-hexafluoropropylene) (PVDH-HFP) porous membrane electrolyte enhanced with lithium bis(trifluoromethane sulphone)imide (LiTFSI) and lithium aluminum titanium phosphate (LATP), with an ionic conductivity of 2.1 × 10-3 S cm-1. Combining ceramic (LATP) with the gel structure of PVDF-HFP and LiTFSI ionic liquid harnesses benefits of ceramic and gel electrolytes in providing flexible electrolytes with a high ionic conductivity. In a flexibility test experiment, bending the polymer electrolyte at 90° for 20 times resulted in 14% decrease in ionic conductivity. Efforts to further improving the flexibility of the presented electrolyte are ongoing. Using this electrolyte, full-cell batteries with lithium titanium oxide (LTO) and lithium cobalt oxide (LCO) electrodes and (i) standard metallic current collectors and (ii) paper-based current collectors were fabricated and tested. The achieved specific capacities were (i) 123 mAh g-1 for standard metallic current collectors and (ii) 99.5 mAh g-1 for paper-based current collectors. Thus, the presented electrolyte has potential to become a viable candidate in paper-based and flexible battery applications. Fabrication methods, experimental procedures, and test results for the polymer gel electrolyte and batteries are presented and discussed.

Expression of Aspergillus niger CAZymes is determined by compositional changes in wheat straw generated by hydrothermal or ionic liquid pretreatments

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

Daly, Paul; van Munster, Jolanda M.; Blythe, Martin J.

The capacity of fungi, such as Aspergillus niger, to degrade lignocellulose is harnessed in biotechnology to generate biofuels and high-value compounds from renewable feedstocks. Most feedstocks are currently pretreated to increase enzymatic digestibility: improving our understanding of the transcriptomic responses of fungi to pretreated lignocellulosic substrates could help to improve the mix of activities and reduce the production costs of commercial lignocellulose saccharifying cocktails. We investigated the responses of A. niger to untreated, ionic liquid and hydrothermally pretreated wheat straw over a 5-day time course using RNA-seq and targeted proteomics. The ionic liquid pretreatment altered the cellulose crystallinity while retainingmore » more of the hemicellulosic sugars than the hydrothermal pretreatment. Ionic liquid pretreatment of straw led to a dynamic induction and repression of genes, which was correlated with the higher levels of pentose sugars saccharified from the ionic liquid-pretreated straw. Hydrothermal pretreatment of straw led to reduced levels of transcripts of genes encoding carbohydrate-active enzymes as well as the derived proteins and enzyme activities. Both pretreatments abolished the expression of a large set of genes encoding pectinolytic enzymes. These reduced levels could be explained by the removal of parts of the lignocellulose by the hydrothermal pretreatment. The time course also facilitated identification of temporally limited gene induction patterns. The presented transcriptomic and biochemical datasets demonstrate that pretreatments caused modifications of the lignocellulose, to both specific structural features as well as the organisation of the overall lignocellulosic structure, that determined A. niger transcript levels. The experimental setup allowed reliable detection of substrate-specific gene expression patterns as well as hitherto non-expressed genes. Our data suggest beneficial effects of using untreated and IL-pretreated straw, but not HT-pretreated straw, as feedstock for CAZyme production.« less

Expression of Aspergillus niger CAZymes is determined by compositional changes in wheat straw generated by hydrothermal or ionic liquid pretreatments

DOE PAGES

Daly, Paul; van Munster, Jolanda M.; Blythe, Martin J.; ...

2017-02-07

The capacity of fungi, such as Aspergillus niger, to degrade lignocellulose is harnessed in biotechnology to generate biofuels and high-value compounds from renewable feedstocks. Most feedstocks are currently pretreated to increase enzymatic digestibility: improving our understanding of the transcriptomic responses of fungi to pretreated lignocellulosic substrates could help to improve the mix of activities and reduce the production costs of commercial lignocellulose saccharifying cocktails. We investigated the responses of A. niger to untreated, ionic liquid and hydrothermally pretreated wheat straw over a 5-day time course using RNA-seq and targeted proteomics. The ionic liquid pretreatment altered the cellulose crystallinity while retainingmore » more of the hemicellulosic sugars than the hydrothermal pretreatment. Ionic liquid pretreatment of straw led to a dynamic induction and repression of genes, which was correlated with the higher levels of pentose sugars saccharified from the ionic liquid-pretreated straw. Hydrothermal pretreatment of straw led to reduced levels of transcripts of genes encoding carbohydrate-active enzymes as well as the derived proteins and enzyme activities. Both pretreatments abolished the expression of a large set of genes encoding pectinolytic enzymes. These reduced levels could be explained by the removal of parts of the lignocellulose by the hydrothermal pretreatment. The time course also facilitated identification of temporally limited gene induction patterns. The presented transcriptomic and biochemical datasets demonstrate that pretreatments caused modifications of the lignocellulose, to both specific structural features as well as the organisation of the overall lignocellulosic structure, that determined A. niger transcript levels. The experimental setup allowed reliable detection of substrate-specific gene expression patterns as well as hitherto non-expressed genes. Our data suggest beneficial effects of using untreated and IL-pretreated straw, but not HT-pretreated straw, as feedstock for CAZyme production.« less

Controlling Ionic Transport for Device Design in Synthetic Nanopores

NASA Astrophysics Data System (ADS)

Kalman, Eric Boyd

Polymer nanopores present a number of behaviors not seen in microscale systems, such as ion current rectification, ionic selectivity, size exclusion and potential dependent ion concentrations in and near the pore. The existence of these effects stems from the small size of nanopores with respect to the characteristic length scales of surface interactions at the interface between the nanopore surface and the solution within it. The large surface-to-volume ratio due to the nanoscale geometry of a nanopore, as well as similarity in scale between geometry and interaction demands the solution interact with the nanopore walls. As surfaces in solution almost always carry residual charge, these surface forces are primarily the electrostatic interactions between the charge groups on the pore surface and the ions in solution. These interactions may be used by the experimentalist to control ionic transport through synthetic nanopores, and use them as a template for the construction of devices. In this research, we present our work on creating a number of ionic analogs to seminal electronic devices, specifically diodes, and transistors, by controlling ionic transport through the electrostatic interactions between a single synthetic nanopore and ions. Control is achieved by "doping" the effective charge carrier concentration in specific regions of the nanopore through manipulation of the pore's surface charge. This manipulation occurs through two mechanisms: chemical modification of the surface charge and electrostatic manipulation of the local internal nanopore potential using a gate electrode. Additionally, the innate selectivity of the charged nanopores walls allows for the separation of charges in solution. This well-known effect, which spawns measureable quantities, the streaming potential and current, has been used to create nanoscale water desalination membranes. We attempt to create a device using membranes with large nanopore densities for the desalination of water which should theoretically outperform currently available devices, as through our previous work we have developed techniques allowing for transport manipulation not current accessible in traditional membrane motifs.

Microfludic Device for Creating Ionic Strength Gradients over DNA Microarrays for Efficient DNA Melting Studies and Assay Development

PubMed Central

Petersen, Jesper; Poulsen, Lena; Birgens, Henrik; Dufva, Martin

2009-01-01

The development of DNA microarray assays is hampered by two important aspects: processing of the microarrays is done under a single stringency condition, and characteristics such as melting temperature are difficult to predict for immobilized probes. A technical solution to these limitations is to use a thermal gradient and information from melting curves, for instance to score genotypes. However, application of temperature gradients normally requires complicated equipment, and the size of the arrays that can be investigated is restricted due to heat dissipation. Here we present a simple microfluidic device that creates a gradient comprising zones of defined ionic strength over a glass slide, in which each zone corresponds to a subarray. Using this device, we demonstrated that ionic strength gradients function in a similar fashion as corresponding thermal gradients in assay development. More specifically, we noted that (i) the two stringency modulators generated melting curves that could be compared, (ii) both led to increased assay robustness, and (iii) both were associated with difficulties in genotyping the same mutation. These findings demonstrate that ionic strength stringency buffers can be used instead of thermal gradients. Given the flexibility of design of ionic gradients, these can be created over all types of arrays, and encompass an attractive alternative to temperature gradients, avoiding curtailment of the size or spacing of subarrays on slides associated with temperature gradients. PMID:19277213

Microfludic device for creating ionic strength gradients over DNA microarrays for efficient DNA melting studies and assay development.

PubMed

Petersen, Jesper; Poulsen, Lena; Birgens, Henrik; Dufva, Martin

2009-01-01

The development of DNA microarray assays is hampered by two important aspects: processing of the microarrays is done under a single stringency condition, and characteristics such as melting temperature are difficult to predict for immobilized probes. A technical solution to these limitations is to use a thermal gradient and information from melting curves, for instance to score genotypes. However, application of temperature gradients normally requires complicated equipment, and the size of the arrays that can be investigated is restricted due to heat dissipation. Here we present a simple microfluidic device that creates a gradient comprising zones of defined ionic strength over a glass slide, in which each zone corresponds to a subarray. Using this device, we demonstrated that ionic strength gradients function in a similar fashion as corresponding thermal gradients in assay development. More specifically, we noted that (i) the two stringency modulators generated melting curves that could be compared, (ii) both led to increased assay robustness, and (iii) both were associated with difficulties in genotyping the same mutation. These findings demonstrate that ionic strength stringency buffers can be used instead of thermal gradients. Given the flexibility of design of ionic gradients, these can be created over all types of arrays, and encompass an attractive alternative to temperature gradients, avoiding curtailment of the size or spacing of subarrays on slides associated with temperature gradients.

Realisation of an all solid state lithium battery using solid high temperature plastic crystal electrolytes exhibiting liquid like conductivity.

PubMed

Shekibi, Youssof; Rüther, Thomas; Huang, Junhua; Hollenkamp, Anthony F

2012-04-07

Replacement of volatile and combustible electrolytes in conventional lithium batteries is desirable for two reasons: safety concerns and increase in specific energy. In this work we consider the use of an ionic organic plastic crystal material (IOPC), N-ethyl-N-methylpyrrolidinium tetrafluoroborate, [C2mpyr][BF(4)], as a solid-state electrolyte for lithium battery applications. The effect of inclusion of 1 to 33 mol% lithium tetrafluoroborate, LiBF(4), into [C2mpyr][BF(4)] has been investigated over a wide temperature range by differential scanning calorimetry (DSC), impedance spectroscopy, cyclic voltammetry and cycling of full Li|LiFePO(4) batteries. The increases in ionic conductivity by orders of magnitude observed at higher temperature are most likely associated with an increase in Li ion mobility in the highest plastic phase. At concentrations >5 mol% LiBF(4) the ionic conductivity of these solid-state composites is comparable to the ionic conductivity of room temperature ionic liquids. Galvanostatic cycling of Li|Li symmetrical cells showed that the reversibility of the lithium metal redox reaction at the interface of this plastic crystal electrolyte is sufficient for lithium battery applications. For the first time we demonstrate an all solid state lithium battery incorporating solid electrolytes based on IOPC as opposed to conventional flammable organic solvents.

Structure and thermal properties of salicylate-based-protic ionic liquids as new heat storage media. COSMO-RS structure characterization and modeling of heat capacities.

PubMed

Jacquemin, Johan; Feder-Kubis, Joanna; Zorębski, Michał; Grzybowska, Katarzyna; Chorążewski, Mirosław; Hensel-Bielówka, Stella; Zorębski, Edward; Paluch, Marian; Dzida, Marzena

2014-02-28

During this research, we present a study on the thermal properties, such as the melting, cold crystallization, and glass transition temperatures as well as heat capacities from 293.15 K to 323.15 K of nine in-house synthesized protic ionic liquids based on the 3-(alkoxymethyl)-1H-imidazol-3-ium salicylate ([H-Im-C1OC(n)][Sal]) with n = 3-11. The 3D structures, surface charge distributions and COSMO volumes of all investigated ions are obtained by combining DFT calculations and the COSMO-RS methodology. The heat capacity data sets as a function of temperature of the 3-(alkoxymethyl)-1H-imidazol-3-ium salicylate are then predicted using the methodology originally proposed in the case of ionic liquids by Ge et al. 3-(Alkoxymethyl)-1H-imidazol-3-ium salicylate based ionic liquids present specific heat capacities higher in many cases than other ionic liquids that make them suitable as heat storage media and in heat transfer processes. It was found experimentally that the heat capacity increases linearly with increasing alkyl chain length of the alkoxymethyl group of 3-(alkoxymethyl)-1H-imidazol-3-ium salicylate as was expected and predicted using the Ge et al. method with an overall relative absolute deviation close to 3.2% for temperatures up to 323.15 K.

Dissecting ion-specific dielectric spectra of sodium-halide solutions into solvation water and ionic contributions

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

Rinne, Klaus F.; Netz, Roland R.; Gekle, Stephan

2014-12-07

Using extensive equilibrium molecular dynamics simulations we determine the dielectric spectra of aqueous solutions of NaF, NaCl, NaBr, and NaI. The ion-specific and concentration-dependent shifts of the static dielectric constants and the dielectric relaxation times match experimental results very well, which serves as a validation of the classical and non-polarizable ionic force fields used. The purely ionic contribution to the dielectric response is negligible, but determines the conductivity of the salt solutions. The ion-water cross correlation contribution is negative and reduces the total dielectric response by about 5%-10% for 1 M solutions. The dominating water dielectric response is decomposed into differentmore » water solvation shells and ion-pair configurations, by this the spectral blue shift and the dielectric decrement of salt solutions with increasing salt concentration is demonstrated to be primarily caused by first-solvation shell water. With rising salt concentration the simulated spectra show more pronounced deviations from a single-Debye form and can be well described by a Cole-Cole fit, in quantitative agreement with experiments. Our spectral decomposition into ionic and different water solvation shell contributions does not render the individual contributions more Debye-like, this suggests the non-Debye-like character of the dielectric spectra of salt solutions not to be due to the superposition of different elementary relaxation processes with different relaxation times. Rather, the non-Debye-like character is likely to be an inherent spectral signature of solvation water around ions.« less

Ionic channels underlying the ventricular action potential in zebrafish embryo.

PubMed

Alday, Aintzane; Alonso, Hiart; Gallego, Monica; Urrutia, Janire; Letamendia, Ainhoa; Callol, Carles; Casis, Oscar

2014-06-01

Over the last years zebrafish has become a popular model in the study of cardiac physiology, pathology and pharmacology. Recently, the application of the 3Rs regulation and the characteristics of the embryo have reduced the use of adult zebrafish use in many studies. However, the zebrafish embryo cardiac physiology is poorly characterized since most works have used indirect techniques and direct recordings of cardiac action potential and ionic currents are scarce. In order to optimize the zebrafish embryo model, we used electrophysiological, pharmacological and immunofluorescence tools to identify the characteristics and the ionic channels involved in the ventricular action potentials of zebrafish embryos. The application of Na(+) or T-type Ca(+2) channel blockers eliminated the cardiac electrical activity, indicating that the action potential upstroke depends on Na(+) and T-type Ca(+2) currents. The plateau phase depends on L-type Ca(+2) channels since it is abolished by specific blockade. The direct channel blockade indicates that the action potential repolarization and diastolic potential depends on ERG K(+) channels. The presence in the embryonic heart of the Nav1.5, Cav1.2, Cav3.2 and ERG channels was also confirmed by immunofluorescence, while the absence of effect of specific blockers and immunostaining indicate that two K(+) repolarizing currents present in human heart, Ito and IKs, are absent in the embryonic zebrafish heart. Our results describe the ionic channels present and its role in the zebrafish embryo heart and support the use of zebrafish embryos to study human diseases and their use for drug testing. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effect of electrolytes on proteins physisorption on ordered mesoporous silica materials.

PubMed

Salis, Andrea; Medda, Luca; Cugia, Francesca; Monduzzi, Maura

2016-01-01

This short review highlights the effect of electrolytes on the performance of proteins-mesoporous silica conjugates which can open interesting perspectives in biotechnological fields, particularly nanomedicine and biocatalysis. Indeed therapeutic proteins and peptides represent a challenging innovation for several kinds of diseases, but since their self-life in biological fluids is very short, they need a stealth protective carrier. Similarly, enzymes need a solid support to improve thermal stability and to allow for recycling. Ordered mesoporous silica materials represent a valid choice as widely demonstrated. Both proteins and silica mesoporous materials possess charged surfaces, and here, the crucial role of pH, buffer, ionic strength and electrolyte type is posed in relation with loading/release of proteins onto/from the silica support through the analysis of adsorption and release processes. A delicate interplay of electrostatic and van der Waals interactions arises from considering electrolytes' effects on the two different charged surfaces. Clear outcomes concern the effect of pH and ionic strength. Protein loading onto the silica matrix is favored by an adsorbing solution having a pH close to the protein pI, and by a high ionic strength that reduces the Debye length. Release is instead favored by an adsorbing solution characterized by an intermediate ionic strength, close to the physiological values. Significant specific ions effects are shown to affect both proteins and silica matrices, as well as protein adsorption onto silica matrices. Further work is needed to quantify specific ion effects on the preservation of the biological activity, and on the release performance. Copyright © 2015 Elsevier B.V. All rights reserved.

Tuning of protein-surfactant interaction to modify the resultant structure.

PubMed

Mehan, Sumit; Aswal, Vinod K; Kohlbrecher, Joachim

2015-09-01

Small-angle neutron scattering and dynamic light scattering studies have been carried out to examine the interaction of bovine serum albumin (BSA) protein with different surfactants under varying solution conditions. We show that the interaction of anionic BSA protein (pH7) with surfactant and the resultant structure are strongly modified by the charge head group of the surfactant, ionic strength of the solution, and mixed surfactants. The protein-surfactant interaction is maximum when two components are oppositely charged, followed by components being similarly charged through the site-specific binding, and no interaction in the case of a nonionic surfactant. This interaction of protein with ionic surfactants is characterized by the fractal structure representing a bead-necklace structure of micellelike clusters adsorbed along the unfolded protein chain. The interaction is enhanced with ionic strength only in the case of site-specific binding of an anionic surfactant with an anionic protein, whereas it is almost unchanged for other complexes of cationic and nonionic surfactants with anionic proteins. Interestingly, the interaction of BSA protein with ionic surfactants is significantly suppressed in the presence of nonionic surfactant. These results with mixed surfactants thus can be used to fold back the unfolded protein as well as to prevent surfactant-induced protein unfolding. For different solution conditions, the results are interpreted in terms of a change in fractal dimension, the overall size of the protein-surfactant complex, and the number of micelles attached to the protein. The interplay of electrostatic and hydrophobic interactions is found to govern the resultant structure of complexes.

Tuning of protein-surfactant interaction to modify the resultant structure

NASA Astrophysics Data System (ADS)

Mehan, Sumit; Aswal, Vinod K.; Kohlbrecher, Joachim

2015-09-01

Small-angle neutron scattering and dynamic light scattering studies have been carried out to examine the interaction of bovine serum albumin (BSA) protein with different surfactants under varying solution conditions. We show that the interaction of anionic BSA protein (p H 7 ) with surfactant and the resultant structure are strongly modified by the charge head group of the surfactant, ionic strength of the solution, and mixed surfactants. The protein-surfactant interaction is maximum when two components are oppositely charged, followed by components being similarly charged through the site-specific binding, and no interaction in the case of a nonionic surfactant. This interaction of protein with ionic surfactants is characterized by the fractal structure representing a bead-necklace structure of micellelike clusters adsorbed along the unfolded protein chain. The interaction is enhanced with ionic strength only in the case of site-specific binding of an anionic surfactant with an anionic protein, whereas it is almost unchanged for other complexes of cationic and nonionic surfactants with anionic proteins. Interestingly, the interaction of BSA protein with ionic surfactants is significantly suppressed in the presence of nonionic surfactant. These results with mixed surfactants thus can be used to fold back the unfolded protein as well as to prevent surfactant-induced protein unfolding. For different solution conditions, the results are interpreted in terms of a change in fractal dimension, the overall size of the protein-surfactant complex, and the number of micelles attached to the protein. The interplay of electrostatic and hydrophobic interactions is found to govern the resultant structure of complexes.

Non-aqueous homogenous biocatalytic conversion of polysaccharides in ionic liquids using chemically modified glucosidase.

PubMed

Brogan, Alex P S; Bui-Le, Liem; Hallett, Jason P

2018-06-25

The increasing requirement to produce platform chemicals and fuels from renewable sources means advances in biocatalysis are rapidly becoming a necessity. Biomass is widely used in nature as a source of energy and as chemical building blocks. However, recalcitrance towards traditional chemical processes and solvents provides a significant barrier to widespread utility. Here, by optimizing enzyme solubility in ionic liquids, we have discovered solvent-induced substrate promiscuity of glucosidase, demonstrating an unprecedented example of homogeneous enzyme bioprocessing of cellulose. Specifically, chemical modification of glucosidase for solubilization in ionic liquids can increase thermal stability to up to 137 °C, allowing for enzymatic activity 30 times greater than is possible in aqueous media. These results establish that through a synergistic combination of chemical biology (enzyme modification) and reaction engineering (solvent choice), the biocatalytic capability of enzymes can be intensified: a key step towards the full-scale deployment of industrial biocatalysis.

Recent progress in biopolymer nanoparticle and microparticle formation by heat-treating electrostatic protein-polysaccharide complexes.

PubMed

Jones, Owen G; McClements, David Julian

2011-09-14

Functional biopolymer nanoparticles or microparticles can be formed by heat treatment of globular protein-ionic polysaccharide electrostatic complexes under appropriate solution conditions. These biopolymer particles can be used as encapsulation and delivery systems, fat mimetics, lightening agents, or texture modifiers. This review highlights recent progress in the design and fabrication of biopolymer particles based on heating globular protein-ionic polysaccharide complexes above the thermal denaturation temperature of the proteins. The influence of biopolymer type, protein-polysaccharide ratio, pH, ionic strength, and thermal history on the characteristics of the biopolymer particles formed is reviewed. Our current understanding of the underlying physicochemical mechanisms of particle formation and properties is given. The information provided in this review should facilitate the rational design of biopolymer particles with specific physicochemical and functional attributes, as well as stimulate further research in identifying the physicochemical origin of particle formation. Copyright © 2010 Elsevier B.V. All rights reserved.

High Performance Variable Emittance Devices for Spacecraft Application Based on Conducting Polymers Coupled with Ionic Liquids

NASA Astrophysics Data System (ADS)

Chandrasekhar, Prasanna; Zay, Brian J.; Barbolt, Scott; Werner, Robert; Birur, Gajanana C.; Paris, Anthony

2009-03-01

This contribution describes the fabrication, function and performance of thin-film variable emittance electrochromic skins fabricated using poly(aniline) as the conducting polymer (CP), a long-chain polymeric dopant, and an ionic liquid as electrolyte. The ionic electrolyte allows operation in space vacuum without any seals. A unique, space-durable coating applied to the external surface of the skins drastically lowers the solar absorptance of the skins, such that in their dark (highly emissive) electrochromic state, it is no more than 0.44, whilst in their light electrochromic state, it is ca. 0.3. Data presented show tailorable, variations from 0.19 to 0.90, ∀(s)<0.3, and nearly indefinite cyclability. Extended thermal vacuum, atomic-O, micrometeoroid, VUV and other studies show excellent space durability. Performance of a doughnut-shaped skin designed for a specific micro-spacecraft is also described.

Comparing two tetraalkylammonium ionic liquids. II. Phase transitions.

PubMed

Lima, Thamires A; Paschoal, Vitor H; Faria, Luiz F O; Ribeiro, Mauro C C; Ferreira, Fabio F; Costa, Fanny N; Giles, Carlos

2016-06-14

Phase transitions of the ionic liquids n-butyl-trimethylammonium bis(trifluoromethanesulfonyl)imide, [N1114][NTf2], and methyl-tributylammonium bis(trifluoromethanesulfonyl)imide, [N1444][NTf2], were investigated by differential scanning calorimetry (DSC), X-ray diffraction (XRD) measurements, and Raman spectroscopy. XRD and Raman spectra were obtained as a function of temperature at atmospheric pressure, and also under high pressure at room temperature using a diamond anvil cell (DAC). [N1444][NTf2] experiences glass transition at low temperature, whereas [N1114][NTf2] crystallizes or not depending on the cooling rate. Both the ionic liquids exhibit glass transition under high pressure. XRD and low-frequency Raman spectra provide a consistent physical picture of structural ordering-disordering accompanying the thermal events of crystallization, glass transition, cold crystallization, pre-melting, and melting. Raman spectra in the high-frequency range of some specific cation and anion normal modes reveal conformational changes of the molecular structures along phase transitions.

Enhanced photophysics of conjugated polymers

DOEpatents

Chen, Liaohai [Argonne, IL; Xu, Su [Santa Clara, CA; McBranch, Duncan [Santa Fe, NM; Whitten, David [Santa Fe, NM

2003-05-27

The addition of oppositely charged surfactant to fluorescent ionic conjugated polymer forms a polymer-surfactant complex that exhibits at least one improved photophysical property. The conjugated polymer is a fluorescent ionic polymer that typically has at least one ionic side chain or moiety that interacts with the specific surfactant selected. The photophysical property improvements may include increased fluorescence quantum efficiency, wavelength-independent emission and absorption spectra, and more stable fluorescence decay kinetics. The complexation typically occurs in a solution of a polar solvent in which the polymer and surfactant are soluble, but it may also occur in a mixture of solvents. The solution is commonly prepared with a surfactant molecule:monomer repeat unit of polymer ratio ranging from about 1:100 to about 1:1. A polymer-surfactant complex precipitate is formed as the ratio approaches 1:1. This precipitate is recoverable and usable in many forms.

Structure and diffusion of furans and other cellulose-derived compounds in solvents via MD simulation

NASA Astrophysics Data System (ADS)

Rabideau, Brooks; Ismail, Ahmed

2011-03-01

There is now a large push towards the development of energy sources that are both environmentally friendly and sustainable; with the conversion of cellulose derived from biomass into biofuels being one promising route. In this conversion, a variety of intermediary compounds have been identified, which appear critical to successful expansion of the process to an industrial scale. Here we examine the structure and diffusion of these furans and acids derived from cellulose within ionic liquids via molecular dynamic simulation. Ionic liquids have shown the ability to dissolve cellulose with certain `green' benefits over existing, conventional solvents. Specifically, we study the solvation properties of these chemicals by examining the pair correlation functions of solute with solvent, and by exploring the agglomeration and separation of these chemicals from the solvent as well as the hydrogen bonding between species. Additionally, we determine the diffusion constant of these compounds in ionic liquid and aqueous solvents.

Water uptake, ionic conductivity and swelling properties of anion-exchange membrane

NASA Astrophysics Data System (ADS)

Duan, Qiongjuan; Ge, Shanhai; Wang, Chao-Yang

2013-12-01

Water uptake, ionic conductivity and dimensional change of the anion-exchange membrane made by Tokuyama Corporation (A201 membrane) are investigated at different temperatures and water activities. Specifically, the amount of water taken up by membranes exposed to water vapor and membranes soaked in liquid water is determined. The water uptake of the A201 membrane increases with water content as well as temperature. In addition, water sorption data shows Schroeder's paradox for the AEMs investigated. The swelling properties of the A201 membrane exhibit improved dimensional stability compared with Nafion membrane. Water sorption of the A201 membrane occurs with a substantial negative excess volume of mixing. The threshold value of hydrophilic fraction in the A201 membrane for ionic conductivity is around 0.34, above which, the conductivity begins to rise quickly. This indicates that a change in the connectivity of the hydrophilic domains occurs when hydrophilic fraction approaches 0.34.

Linear finite-difference bond graph model of an ionic polymer actuator

NASA Astrophysics Data System (ADS)

Bentefrit, M.; Grondel, S.; Soyer, C.; Fannir, A.; Cattan, E.; Madden, J. D.; Nguyen, T. M. G.; Plesse, C.; Vidal, F.

2017-09-01

With the recent growing interest for soft actuation, many new types of ionic polymers working in air have been developed. Due to the interrelated mechanical, electrical, and chemical properties which greatly influence the characteristics of such actuators, their behavior is complex and difficult to understand, predict and optimize. In light of this challenge, an original linear multiphysics finite difference bond graph model was derived to characterize this ionic actuation. This finite difference scheme was divided into two coupled subparts, each related to a specific physical, electrochemical or mechanical domain, and then converted into a bond graph model as this language is particularly suited for systems from multiple energy domains. Simulations were then conducted and a good agreement with the experimental results was obtained. Furthermore, an analysis of the power efficiency of such actuators as a function of space and time was proposed and allowed to evaluate their performance.

Performance of Liquid Phase Exfoliated Graphene As Electrochemical Double Layer Capacitors Electrodes

NASA Astrophysics Data System (ADS)

Huffstutler, Jacob; Wasala, Milinda; Richie, Julianna; Winchester, Andrew; Ghosh, Sujoy; Kar, Swastik; Talapatra, Saikat

2014-03-01

We will present the results of our investigations of electrochemical double layer capacitors (EDLCs) or supercapacitors (SC) fabricated using liquid-phase exfoliated graphene. Several electrolytes, such as aqueous potassium hydroxide KOH (6M), ionic 1-Butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6], and ionic 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate[BMP][FAP] were used. These EDLC's show good performance compared to other carbon nanomaterials based EDLC's devices. We found that the liquid phase exfoliated graphene based devices possess specific capacitance values as high as 262 F/g, when used with ionic liquid electrolyte[BMP][FAP], with power densities (~ 454 W/kg) and energy densities (~ 0.38Wh/kg). Further, these devices indicated rapid charge transfer response even without the use of any binders or specially prepared current collectors. A detailed electrochemical impedance spectroscopy analysis in order to understand the phenomenon of charge storage in these materials will be presented.

Protein Stabilization and Enzyme Activation in Ionic Liquids: Specific Ion Effects

PubMed Central

Zhao, Hua

2015-01-01

There are still debates on whether the hydration of ions perturbs the water structure, and what is the degree of such disturbance; therefore, the origin of Hofmeister effect on protein stabilization continues being questioned. For this reason, it is suggested to use the ‘specific ion effect’ instead of other misleading terms such as Hofmeister effect, Hofmeister series, lyotropic effect, and lyotropic series. In this review, we firstly discuss the controversial aspect of inorganic ion effects on water structures, and several possible contributors to the specific ion effect of protein stability. Due to recent overwhelming attraction of ionic liquids (ILs) as benign solvents in many enzymatic reactions, we further evaluate the structural properties and molecular-level interactions in neat ILs and their aqueous solutions. Next, we systematically compare the specific ion effects of ILs on enzyme stability and activity, and conclude that (a) the specificity of many enzymatic systems in diluted aqueous IL solutions is roughly in line with the traditional Hofmeister series albeit some exceptions; (b) however, the specificity follows a different track in concentrated or neat ILs because other factors (such as hydrogen-bond basicity, nucelophilicity, and hydrophobicity, etc) are playing leading roles. In addition, we demonstrate some examples of biocatalytic reactions in IL systems that are guided by the empirical specificity rule. PMID:26949281

[Difference in ionic specificity of ATP synthesis in extremely alkalophilic sulfate-reducing and acetogenic bacteria].

PubMed

Pitriuk, A V; Pusheva, M A

2001-01-01

Ionic specificity of oxidative phosphorylation was studied in Natroniella acetigena and Desulfonatronum lacustre, which are new alkaliphilic anaerobes that were isolated from soda lakes and have a pH growth optimum of 9.5-9.7. The ability of their cells to synthesize ATP in response to the imposition of artificial delta pH+ and delta pNa+ gradients was studied. As distinct from other marine and freshwater sulfate reducers and extremely alkaliphilic anaerobes, D. lacustre uses a Na(+)-translocating ATPase for ATP synthesis. The alkaliphilic acetogen N. acetigena, which develops at a much higher Na+ concentration in the medium, generated primary delta pH+ for ATP synthesis. Thus, the high Na+ concentrations and alkaline pH values typical of soda lakes do not predetermine the type of bioenergetics of their inhabitants.

Lithium insertion in graphite from ternary ionic liquid-lithium salt electrolytes: II. Evaluation of specific capacity and cycling efficiency and stability at room temperature

NASA Astrophysics Data System (ADS)

Lux, Simon F.; Schmuck, Martin; Appetecchi, Giovanni B.; Passerini, Stefano; Winter, Martin; Balducci, Andrea

In this paper we report the results about the use of ternary room temperature ionic liquid-lithium salt mixtures as electrolytes for lithium-ion battery systems. Mixtures of N-methyl- N-propyl pyrrolidinium bis(fluorosulfonyl) imide, PYR 13FSI, and N-butyl- N-methylpyrrolidinium bis(trifluoromethansulfonyl) imide, PYR 14TFSI, with lithium hexafluorophosphate, LiPF 6 and lithium bis(trifluoromethansulfonyl) imide, LiTFSI, containing 5 wt.% of vinylene carbonate (VC) as additive, have been used in combination with a commercial graphite, KS6 TIMCAL. The performance of the graphite electrodes has been considered in term of specific capacity, cycling efficiency and cycling stability. The results clearly show the advantage of the use of ternary mixtures on the performance of the graphite electrode.

Neptunium(V) Adsorption to Bacteria at Low and High Ionic Strength

NASA Astrophysics Data System (ADS)

Ams, D.; Swanson, J. S.; Reed, D. T.

2010-12-01

Np(V) is expected to be the predominant oxidation state of neptunium in aerobic natural waters. Np(V), as the NpO2+ aquo and associated complexed species, is readily soluble, interacts weakly with geologic media, and has a high redox stability under a relatively wide range of subsurface conditions. These chemical properties, along with a long half-life make it a primary element of concern regarding long-term nuclear waste storage and subsurface containment. The fate and transport of neptunium in the environment may be influenced by adsorption onto bacterial surfaces. The adsorption of neptunium to bacterial surfaces ties the mobility of the contaminant to the mobility of the bacterium. In this study, the adsorption of the neptunyl (NpO2+) ion was evaluated at low ionic strength on a common soil bacterium and at high ionic strength on a halophilic bacterium isolated from a briny groundwater near the Waste Isolation Pilot Plant (WIPP) in southeast New Mexico. Adsorption experiments were performed in batch reactors as a function of pH, ionic strength, and bacteria/Np mass ratio. Np(V) adsorption was modeled using a surface complexation approach with the mathematical program FITEQL to determine functional group specific binding constants. The data from acid and base titrations of the bacteria used were also modeled to estimate the concentrations and deprotonation constants of discrete bacterial surface functional groups. Bacterial functional group characteristics and Np(V) adsorption behavior between the soil bacterium and the halophilic bacterium were compared. These results highlight key similarities and differences in actinide adsorption behavior in environments of significantly different ionic strength. The observed adsorption behavior may be linked to similarities and differences in the characteristics of the moieties between the cell walls of common gram-negative soil and halophilic bacteria. Moreover, differences in adsorption behavior may also reflect ionic strength effects as the electronic double layer is compressed with increasing ionic strength. These results further highlight the importance of electrostatic interactions in the adsorption process between dissolved metals and bacterial surfaces. This work expands the understanding of actinide-bacteria adsorption phenomena to high ionic strength environmental conditions that are relevant as an aid to predicting Np(V) fate and transport behavior in areas such as the vicinity of salt-based nuclear waste repositories and high ionic-strength groundwaters at DOE sites.

Molecular crowding has no effect on the dilution thermodynamics of the biologically relevant cation mixtures.

PubMed

Głogocka, Daria; Przybyło, Magdalena; Langner, Marek

2017-04-01

The ionic composition of intracellular space is rigorously maintained in the expense of high-energy expenditure. It has been recently postulated that the cytoplasmic ionic composition is optimized so the energy cost of the fluctuations of calcium ion concentration is minimized. Specifically, thermodynamic arguments have been produced to show that the presence of potassium ions at concentrations higher than 100 mM reduce extend of the energy dissipation required for the dilution of calcium cations. No such effect has been measured when sodium ions were present in the solution or when the other divalent cation magnesium was diluted. The experimental observation has been interpreted as the indication of the formation of ionic clusters composed of calcium, chloride and potassium. In order to test the possibility that such clusters may be preserved in biological space, the thermodynamics of ionic mixtures dilution in solutions containing albumins and model lipid bilayers have been measured. Obtained thermograms clearly demonstrate that the energetics of calcium/potassium mixture is qualitatively different from calcium/sodium mixture indicating that the presence of the biologically relevant quantities of proteins and membrane hydrophilic surfaces do not interfere with the properties of the intracellular aqueous phase.

[Influence of non-ionic surfactants on sludge dewaterability].

PubMed

Hou, Hai-Pan; Pu, Wen-Hong; Shi, Ya-Fei; Yu, Wen-Hua; Fan, Ming-Ming; Liu, Huan; Yang, Chang-Zhu; Li, Ye; Yang, Jia-Kuan

2012-06-01

The water content of dewatered sludge cake decreases to about 80% by current sludge dewatering technologies, which hardly satisfies the stricter standards of sludge disposal. In order to evaluate the effects of non-ionic surfactants on sludge dewaterability, two kinds of non-ionic surfactants (OPEO and APG) were studied by using two evaluation indexes, i. e. , specific resistance to filtration (SRF) and dewatering efficiency. Moreover, morphologies of conditioned sewage sludge and raw sludge were comparatively investigated. Results showed that non-ionic surfactants can decrease the particle size of sewage sludge floc and generate more homogenous and regular shape, and then improve the dewatering efficiency. APG has better effect on sewage sludge dewatering than OPEO. SRF of conditioned sludge with APG dosage of 0.05% DS decreased to 42% of SRF of raw sludge, and its dewatering efficiency was as high as 93%. Plate-frame pressure filter experiment demonstrated that, the water content of dewatered cake conditioned with APG dosage of 0.05% DS was lower by about 10% than that of dewatered cake without APG, and its dewatering efficiency reached 97%. Therefore, this research provides some reference for the application of APG in sludge dewatering.

Preparation and electrochemical characterization of ionic-conducting lithium lanthanum titanate oxide/polyacrylonitrile submicron composite fiber-based lithium-ion battery separators

NASA Astrophysics Data System (ADS)

Liang, Yinzheng; Ji, Liwen; Guo, Bingkun; Lin, Zhan; Yao, Yingfang; Li, Ying; Alcoutlabi, Mataz; Qiu, Yiping; Zhang, Xiangwu

Lithium lanthanum titanate oxide (LLTO)/polyacrylonitrile (PAN) submicron composite fiber-based membranes were prepared by electrospinning dispersions of LLTO ceramic particles in PAN solutions. These ionic-conducting LLTO/PAN composite fiber-based membranes can be directly used as lithium-ion battery separators due to their unique porous structure. Ionic conductivities were evaluated after soaking the electrospun LLTO/PAN composite fiber-based membranes in a liquid electrolyte, 1 M lithium hexafluorophosphate (LiPF 6) in ethylene carbonate (EC)/ethyl methyl carbonate (EMC) (1:1 vol). It was found that, among membranes with various LLTO contents, 15 wt.% LLTO/PAN composite fiber-based membranes provided the highest ionic conductivity, 1.95 × 10 -3 S cm -1. Compared with pure PAN fiber membranes, LLTO/PAN composite fiber-based membranes had greater liquid electrolyte uptake, higher electrochemical stability window, and lower interfacial resistance with lithium. In addition, lithium//1 M LiPF 6/EC/EMC//lithium iron phosphate cells containing LLTO/PAN composite fiber-based membranes as the separator exhibited high discharge specific capacity of 162 mAh g -1 and good cycling performance at 0.2 C rate at room temperature.

Cycling and rate performance of Li-LiFePO 4 cells in mixed FSI-TFSI room temperature ionic liquids

NASA Astrophysics Data System (ADS)

Lewandowski, A. P.; Hollenkamp, A. F.; Donne, S. W.; Best, A. S.

A study is conducted of the performance of lithium iron(II) phosphate, LiFePO 4, as a cathode material in a lithium secondary battery that features an ionic liquid electrolyte solution and a metallic lithium anode. The electrolyte solution comprises an ionic liquid of a N-methyl-N-alkyl-pyrrolidinium (alkyl = n-propyl or n-butyl) cation and either the bis(fluorosulfonyl)imide [(FSO 2) 2N -] or bis(trifluoromethanesulfonyl)imide [(F 3CSO 2) 2N -] anion, together with 0.5 mol kg -1 of lithium bis(trifluoromethanesulfonyl)imide salt. For N-methyl-N-propyl-pyrrolidinium bis(fluorosulfonyl)imide, coin cells discharging at rates of C/10 and 4C yield specific capacities of 153 and 110 mAh g -1, respectively, at an average coulombic efficiency of 99.8%. This performance is maintained for over 400 cycles at 50 °C and therefore indicates that these electrolyte solutions support long-term cycling of both LiFePO 4 and metallic lithium while, due to the negligible volatility of ionic liquids, surrounding the lithium in an inherently safe, non-flammable medium.

Reactive solid surface morphology variation via ionic diffusion.

PubMed

Sun, Zhenchao; Zhou, Qiang; Fan, Liang-Shih

2012-08-14

In gas-solid reactions, one of the most important factors that determine the overall reaction rate is the solid morphology, which can be characterized by a combination of smooth, convex and concave structures. Generally, the solid surface structure varies in the course of reactions, which is classically noted as being attributed to one or more of the following three mechanisms: mechanical interaction, molar volume change, and sintering. Here we show that if a gas-solid reaction involves the outward ionic diffusion of a solid-phase reactant then this outward ionic diffusion could eventually smooth the surface with an initial concave and/or convex structure. Specifically, the concave surface is filled via a larger outward diffusing surface pointing to the concave valley, whereas the height of the convex surface decreases via a lower outward diffusion flux in the vertical direction. A quantitative 2-D continuum diffusion model is established to analyze these two morphological variation processes, which shows consistent results with the experiments. This surface morphology variation by solid-phase ionic diffusion serves to provide a fourth mechanism that supplements the traditionally acknowledged solid morphology variation or, in general, porosity variation mechanisms in gas-solid reactions.

Dispersions of polymer ionomers: I.

PubMed

Capek, Ignác

2004-12-31

The principal subject discussed in the current paper is the effect of ionic functional groups in polymers on the formation of nontraditional polymer materials, polymer blends or polymer dispersions. Ionomers are polymers that have a small amount of ionic groups distributed along a nonionic hydrocarbon chain. Specific interactions between components in a polymer blend can induce miscibility of two or more otherwise immiscible polymers. Such interactions include hydrogen bonding, ion-dipole interactions, acid-base interactions or transition metal complexation. Ion-containing polymers provide a means of modifying properties of polymer dispersions by controlling molecular structure through the utilization of ionic interactions. Ionomers having a relatively small number of ionic groups distributed usually along nonionic organic backbone chains can agglomerate into the following structures: (1) multiplets, consisting of a small number of tightly packed ion pairs; and (2) ionic clusters, larger aggregates than multiplets. Ionomers exhibit unique solid-state properties as a result of strong associations among ionic groups attached to the polymer chains. An important potential application of ionomers is in the area of thermoplastic elastomers, where the associations constitute thermally reversible cross-links. The ionic (anionic, cationic or polar) groups are spaced more or less randomly along the polymer chain. Because in this type of ionomer an anionic group falls along the interior of the chain, it trails two hydrocarbon chain segments, and these must be accommodated sterically within any domain structure into which the ionic group enters. The primary effects of ionic functionalization of a polymer are to increase the glass transition temperature, the melt viscosity and the characteristic relaxation times. The polymer microstructure is also affected, and it is generally agreed that in most ionomers, microphase-separated, ion-rich aggregates form as a result of strong ion-dipole attractions. As a consequence of this new phase, additional relaxation processes are often observed in the viscoelastic behavior of ionomers. Light functionalization of polymers can increase the glass transition temperature and gives rise to two new features in viscoelastic behavior: (1) a rubbery plateau above T(g) and (2) a second loss process at elevated temperatures. The rubbery plateau was due to the formation of a physical network. The major effect of the ionic aggregate was to increase the longer time relaxation processes. This in turn increases the melt viscosity and is responsible for the network-like behavior of ionomers above the glass transition temperature. Ionomers rich in polar groups can fulfill the criteria for the self-assembly formation. The reported phenomenon of surface micelle formation has been found to be very general for these materials.

A Cross-Cultural Study of Task Specificity in Creativity

ERIC Educational Resources Information Center

Storme, Martin; Lubart, Todd; Myszkowski, Nils; Cheung, Ping Chung; Tong, Toby; Lau, Sing

2017-01-01

This study provides new evidence concerning task specificity in creativity--examining through a cross-cultural perspective the extent to which performance in graphic versus verbal creativity tasks (domain specificity) and in divergent versus convergent creativity tasks (process specificity) are correlated. The relations between different…

Ionic Liquid-Like Pharmaceutical Ingredients and Applications of Ionic Liquids in Medicinal Chemistry: Development, Status and Prospects.

PubMed

Tang, Jie; Song, Hang; Feng, Xueting; Yohannes, Alula; Yao, Shun

2018-06-05

As a new kind of green media and bioactive compounds with special structure, ionic liquids (ILs) are attracting much attention and applied widely in many fields. However, their roles and potential have not been fully recognized by many researchers of medicinal chemistry. Because of obvious differences from other traditional drugs and reagents, their uses and performance together with advantages and disadvantages need to be explored and reviewed in detail. For systematic and explicit description of the relationship between ILs and medicinal chemistry, all of the contents were elucidated and summarized in a series of independent parts. In each part, it started from the research background or a conceptual framework and then specific examples were introduced to illustrate the theme. Finally, the important conclusions were drawn and its future was outlooked after the discussion about related key problems appearing in each mentioned research. Meanwhile, methodologies such as empirical analysis, comparison and induction were applied in different sections to exposit our subject. The whole review was composed of five parts, and 148 papers were cited in total. Related basic information of ionic liquids was provided on the basis of representative references, including their concepts and important characters. Then 82 papers outlined ionic liquid-like active pharmaceutical ingredients, which unfolded with their major biological activities (antimicrobial activity, antibiofilm activity, antitumor activity, anticholinesterase activity and so on). Applications of ionic liquids in synthesis of drugs and pharmaceutical intermediates were elaborated in 92 papers to illustrate the important roles of ILs and their extraordinary properties in this field. Moreover, new technologies (such as immobilization of IL, microwave reaction, solvent-free synthesis, microreactor, etc) were introduced for further innovation. Finally, 26 papers were included to expound the status about the IL-assisted derivatization of various natural lead compounds. This review placed emphasis on chemical structures of ILs and their structure-activity relationships in a specific manner, leading to meaningful and valuable related information to some related fields and thus promotes further development and application of various ILs for medicinal chemistry. The deep exploration for key scientific problems is the driving force to propel their theoretical breakthrough and industrial production. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Solid-state supercapacitors with ionic liquid based gel polymer electrolyte: Effect of lithium salt addition

NASA Astrophysics Data System (ADS)

Pandey, G. P.; Hashmi, S. A.

2013-12-01

Performance characteristics of the solid-state supercapacitors fabricated with ionic liquid (IL) incorporated gel polymer electrolyte and acid treated multiwalled carbon nanotube (MWCNT) electrodes have been studied. The effect of Li-salt (LiPF6) addition in the IL (1-ethyl-3-methylimidazolium tris(pentafluoroethyl) trifluorophosphate, EMImFAP) based gel electrolyte on the performance of supercapacitors has been specifically investigated. The LiPF6/IL/poly(vinylidine fluoride-co-hexafluoropropylene) (PVdF-HFP) gel electrolyte film possesses excellent electrochemical window of 4 V (from -2.0 to 2.0 V), high ionic conductivity ∼2.6 × 10-3 S cm-1 at 20 °C and high enough thermal stability. The comparative performance of supercapacitors employing electrolytes with and without lithium salt has been evaluated by impedance spectroscopy and cyclic voltammetric studies. The acid-treated MWCNT electrodes show specific capacitance of ∼127 F g-1 with IL/LiPF6 containing gel polymer electrolyte as compared to that with the gel polymer electrolyte without Li-salt, showing the value of ∼76 F g-1. The long cycling stability of the solid state supercapacitor based on the Li-salt containing gel polymer electrolyte confirms the electrochemical stability of the electrolyte.

Biredox ionic liquids: new opportunities toward high performance supercapacitors.

PubMed

Bodin, C; Mourad, E; Zigah, D; Le Vot, S; Freunberger, S A; Favier, F; Fontaine, O

2018-01-01

Nowadays commercial supercapacitors are based on purely capacitive storage at the porous carbons that are used for the electrodes. However, the limits that capacitive storage imposes on energy density calls to investigate new materials to improve the capacitance of the device. This new type of electrodes (e.g., RuO 2 , MnO 2 …) involves pseudo-capacitive faradaic redox processes with the solid material. Ion exchange with solid materials is, however, much slower than the adsorption process in capacitive storage and inevitably leads to significant loss of power. Faradaic process in the liquid state, in contrast can be similarly fast as capacitive processes due to the fast ion transport. Designing new devices with liquid like dynamics and improved specific capacitance is challenging. We present a new approach to increase the specific capacitance using biredox ionic liquids, where redox moieties are tethered to the electrolyte ions, allowing high redox concentrations and significant pseudo-capacitive storage in the liquid state. Anions and cations are functionalized with anthraquinone (AQ) and 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO) moieties, respectively. Glassy carbon, carbon-onion, and commercial activated carbon electrodes that exhibit different double layer structures and thus different diffusion dynamics were used to simultaneously study the electrochemical response of biredox ionic liquids at the positive and negative electrode.

Synthesis of Mesoporous Carbons from Rice Husk for Supercapacitors with High Energy Density in Ionic Liquid Electrolytes.

PubMed

He, Xiaojun; Zhang, Hebao; Xie, Kang; Xia, Youyi; Zhao, Zhigang; Wang, Xiaoting

2016-03-01

High-performance mesoporous carbons (MCs) for supercapacitors were made from rice husk by one-step microwave-assisted ZnCl2 activation. The microstructures of MCs as-made were characterized by field emission scanning electron microscopy and transmission electron microscopy. The pore structure parameters of MCs were obtained by N2 adsorption technique. The electrochemical properties of MC electrodes were studied by constant current charge-discharge, cyclic voltammetry and electrochemical impedance spectroscopy in different electrolytes. The results showed that the specific surface area of MC4 made at the ZnCl2/rice husk mass of 4:1 reached 1737 m2 g(-1). The specific capacitance and energy density of the electrodes fabricated from the mixture of MC4 and microporous carbon increased with the mass percentage of MC4, reaching 157 F g(-1) and 84 Wh kg(-1) at 0.05 A g(-1), and showed good cycle stability in 1-butyl-3-methylimidazolium hexafluorophosphate electrolyte. Compared to the often-used aqueous and organic electrolytes, MC4 capacitor exhibited extremely high energy density in ionic liquid electrolyte, remaining at 28 Wh kg(-1) at 1684 W kg(-1). This work paves a new way to produce cost-effective MCs from biomass for supercapacitors with extremely high energy density in ionic liquid electrolytes.

The effect of switchable water additives on clay settling.

PubMed

Chen, Chien-Shun; Lau, Ying Yin; Mercer, Sean M; Robert, Tobias; Horton, J Hugh; Jessop, Philip G

2013-01-01

The recycling of process water from strip mining extractions is a very relevant task both industrially and environmentally. The sedimentation of fine tailings during such processes, however, can often require long periods of time and/or the addition of flocculants which make later water recycling difficult. We propose the use of switchable water additives as reversible flocculants for clay/water suspensions. Switchable water additives are compounds such as diamines that make it possible to reversibly control the ionic strength of an aqueous solution. Addition of CO(2) to such an aqueous solution causes the ionic strength to rise dramatically, and the change is reversed upon removal of the CO(2). These additives, while in the presence of CO(2), promote the aggregation of clay tailings, reduce settling times, and greatly increase the clarity of the liberated water. The removal of CO(2) from the liberated water regenerates a low ionic strength solution that does not promote clay aggregation and settling until CO(2) is added again. Such reversible behavior would be useful in applications such as oil sands separations in which the recycled water must not promote aggregation. When added to kaolinite and montmorillonite clay suspensions, switchable water provided process waters of lower turbidity than those additives from inorganic salts or by CO(2)-treatment alone. When recollected, the switchable water supernatant was shown to be recyclable over three cycles for enhanced settling of kaolinite. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Characterization of the pH-Mediated solubility of Bacillus thuringiensis var. san diego native δ-endotoxin crystals

Treesearch

C. N. Koller; L. S. Bauer; R. M. Hollingworth

1992-01-01

Native crystals of Bacillus thuringiensis var. san diego, a coleopteran-specific δ-endotoxin, were metabolically labeled with [35S]methionine. Specific activity was 82,000 CPM/μg (2.44 Ci/mmol). Using a universal buffer formulated with the same ionic strength at every pH, we determined that...

Compatibility of Anti-Wear Additives with Non-Ferrous Engine Bearing Alloys

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

Qu, Jun; Zhou, Yan

Investigate the compatibility of engine lubricant antiwear (AW) additives, specifically conventional zinc dialkyldithiophosphate (ZDDP) and newly developed ionic liquids (ILs), with selected non-ferrous engine bearing alloys, specifically aluminum and bronze alloys that are commonly used in connecting rod end journal bearings and bushings, to gain fundamental understanding to guide future development of engine lubricants

Metal-chelating active packaging film enhances lysozyme inhibition of Listeria monocytogenes.

PubMed

Roman, Maxine J; Decker, Eric A; Goddard, Julie M

2014-07-01

Several studies have demonstrated that metal chelators enhance the antimicrobial activity of lysozyme. This study examined the effect of metal-chelating active packaging film on the antimicrobial activity of lysozyme against Listeria monocytogenes. Polypropylene films were surface modified by photoinitiated graft polymerization of acrylic acid (PP-g-PAA) from the food contact surface of the films to impart chelating activity based on electrostatic interactions. PP-g-PAA exhibited a carboxylic acid density of 113 ± 5.4 nmol cm(-2) and an iron chelating activity of 53.7 ± 9.8 nmol cm(-2). The antimicrobial interaction of lysozyme and PP-g-PAA depended on growth media composition. PP-g-PAA hindered lysozyme activity at low ionic strength (2.48-log increase at 64.4 mM total ionic strength) and enhanced lysozyme activity at moderate ionic strength (5.22-log reduction at 120 mM total ionic strength). These data support the hypothesis that at neutral pH, synergy between carboxylate metal-chelating films (pKa(bulk) 6.45) and lysozyme (pI 11.35) is optimal in solutions of moderate to high ionic strength to minimize undesirable charge interactions, such as lysozyme absorption onto film. These findings suggest that active packaging, which chelates metal ions based on ligand-specific interactions, in contrast to electrostatic interactions, may improve antimicrobial synergy. This work demonstrates the potential application of metal-chelating active packaging films to enhance the antimicrobial activity of membrane-disrupting antimicrobials, such as lysozyme.

Specific anion effects on copper surface through electrochemical treatment: Enhanced photoelectrochemical CO2 reduction activity of derived nanostructures induced by chaotropic anions

NASA Astrophysics Data System (ADS)

Navaee, Aso; Salimi, Abdollah

2018-05-01

Copper derivatives are the most prominent CO2 reduction electrocatalyst. Herein, the metallic copper has been electrochemically treated with some of common ionic salts such as N3bar, HPO2bar, S2bar, Fbar, Clbar, Brbar and Ibar based on the dissolution of a metallic working electrode in an aqueous solution to derive the surface roughness incorporated with nanostructures. Diverse surface morphology can be obtained when the ionic radii of anions are changed. Surface study reveals various roughness shapes based on the size and polarity of the anions, where the ions with higher ionic radii have higher impact on the Cu surface. In comparison, polyatomic oxyanion such as HPO2bar even with large ionic radii do not have enough strength to create the surface roughness than that of oxygen-free anions with large ionic radii. The photoelectrochemical behavior of the modified surfaces toward CO2 reduction is studied at a wide potential window in bicarbonate aqueous solution. Based on our investigations, treated surfaces by Ibar, Clbar and S2bargive a more surface roughness, while Ibar and N3bar offer higher catalytic activity toward CO2 reduction due to possible complexing ability of these anions with Cu cations, followed by formation of the co-catalyst semiconductor and facilitate electron transfer. This methodology can be applied to investigate the effect of ions on transition metals along with obtaining different surface morphologies tailored to different applications.

Separation of alpha-lactalbumin grafted- and non-grafted maghemite core/silica shell nanoparticles by capillary zone electrophoresis.

PubMed

Petr, Jan; Teste, Bruno; Descroix, Stéphanie; Siaugue, Jean-Michel; Gareil, Pierre; Varenne, Anne

2010-08-01

The use of nanoparticles (NPs) in immunodiagnostics is a challenging task for many reasons, including the need for miniaturization. In view of the development of an assay dedicated to an original, miniaturized and fully automated immunodiagnostics which aims to mimic in vivo interactions, magnetic zwitterionic bifunctional amino/polyethyleneoxide maghemite core/silica shell NPs functionalized with allergenic alpha-lactalbumin were characterized by CE. Proper analytical performances were obtained through semi-permanent capillary coating with didodecyldimethylammonium bromide (DDAB) or permanent capillary wall modification by hydroxypropylcellulose. The influence of experimental conditions (e.g. buffer component nature, pH, ionic strength, and electric field strength) on sample stability, electrophoretic mobility, and dispersion was investigated using either DDAB- or hydroxypropylcellulose-coated capillaries. Adsorption to the capillary wall and aggregation phenomena were evaluated according to the CE conditions. The proper choice of experimental conditions, i.e. separation under -10 kV in a 25 mM ionic strength MES/NaOH (pH 6.0) with a DDAB-coated capillary, allowed the separation of the grafted and the non-grafted NPs.

A Bibliometric Analysis of Research on Supported Ionic Liquid Membranes during the 1995–2015 Period: Study of the Main Applications and Trending Topics

PubMed Central

Abejón, Ricardo; Pérez-Acebo, Heriberto; Garea, Aurora

2017-01-01

A bibliometric analysis based on Scopus database was performed to identify the global research trends related to Supported Ionic Liquid Membranes (SILMs) during the time period from 1995 to 2015. This work tries to improve the understanding of the most relevant research topics and applications. The results from the analysis reveal that only after 2005 the research efforts focused on SILMs became significant, since the references found before that year are scarce. The most important research works on the four main application groups for SILMs defined in this work (carbon dioxide separation, other gas phase separations, pervaporation and liquid phase separations) were summarized in this paper. Carbon dioxide separation appeared as the application that has received by far the most attention according to the research trends during the analysed period. Comments about other significant applications that are gaining attention, such as the employment of SILMs in analytical tasks or their consideration for the production of fuel cells, have been included. PMID:29112172

Hierarchical micro- and mesoporous carbide-derived carbon as a high-performance electrode material in supercapacitors.

PubMed

Rose, Marcus; Korenblit, Yair; Kockrick, Emanuel; Borchardt, Lars; Oschatz, Martin; Kaskel, Stefan; Yushin, Gleb

2011-04-18

Ordered mesoporous carbide-derived carbon (OM-CDC) materials produced by nanocasting of ordered mesoporous silica templates are characterized by a bimodal pore size distribution with a high ratio of micropores. The micropores result in outstanding adsorption capacities and the well-defined mesopores facilitate enhanced kinetics in adsorption processes. Here, for the first time, a systematic study is presented, in which the effects of synthesis temperature on the electrochemical performance of these materials in supercapacitors based on a 1 M aqueous solution of sulfuric acid and 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid are reported. Cyclic voltammetry shows the specific capacitance of the OM-CDC materials exceeds 200 F g(-1) in the aqueous electrolyte and 185 F g(-1) in the ionic liquid, when measured in a symmetric configuration in voltage ranges of up to 0.6 and 2 V, respectively. The ordered mesoporous channels in the produced OM-CDC materials serve as ion-highways and allow for very fast ionic transport into the bulk of the OM-CDC particles. At room temperature the enhanced ion transport leads to 75% and 90% of the capacitance retention at current densities in excess of ∼10 A g(-1) in ionic liquid and aqueous electrolytes, respectively. The supercapacitors based on 250-300 μm OM-CDC electrodes demonstrate an operating frequency of up to 7 Hz in aqueous electrolyte. The combination of high specific capacitance and outstanding rate capabilities of the OM-CDC materials is unmatched by state-of-the art activated carbons and strictly microporous CDC materials. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High-efficiency extracellular release of free fatty acids from Aspergillus oryzae using non-ionic surfactants.

PubMed

Tamano, Koichi; Miura, Ai; Koike, Hideaki; Kamisaka, Yasushi; Umemura, Myco; Machida, Masayuki

2017-04-20

Free fatty acids (FFAs) are useful for generating biofuel compounds and functional lipids. Microbes are increasingly exploited to produce FFAs via metabolic engineering. However, in many microorganisms, FFAs accumulate in the cytosol, and disrupting cells to extract them is energy intensive. Thus, a simple cost-effective extraction technique must be developed to remove this drawback. We found that FFAs were released from cells of the filamentous fungus Aspergillus oryzae with high efficiency when they were cultured or incubated with non-ionic surfactants such as Triton X-100. The surfactants did not reduce hyphal growth, even at 5% (w/v). When the faaA disruptant was cultured with 1% Triton X-100, more than 80% of the FFAs synthesized de novo were released. When the disruptant cells grown without surfactants were incubated for 1h in 1% Triton X-100 solution, more than 50% of the FFAs synthesized de novo were also released. Other non-ionic surfactants in the same ether series, such as Brij 58, IGEPAL CA-630, and Tergitol NP-40, elicited a similar FFA release. The dry cell weight of total hyphae decreased when grown with 1% Triton X-100. The decrement was 4.9-fold greater than the weight of the released FFAs, implying release of other intracellular compounds. Analysis of the culture supernatant showed that intracellular lactate dehydrogenase was also released, suggesting that FFAs are not released by a specific transporter. Therefore, ether-type non-ionic surfactants probably cause non-specific release of FFAs and other intracellular compounds by increasing cell membrane permeability. Copyright © 2017 Elsevier B.V. All rights reserved.

Adaptable, high recall, event extraction system with minimal configuration.

PubMed

Miwa, Makoto; Ananiadou, Sophia

2015-01-01

Biomedical event extraction has been a major focus of biomedical natural language processing (BioNLP) research since the first BioNLP shared task was held in 2009. Accordingly, a large number of event extraction systems have been developed. Most such systems, however, have been developed for specific tasks and/or incorporated task specific settings, making their application to new corpora and tasks problematic without modification of the systems themselves. There is thus a need for event extraction systems that can achieve high levels of accuracy when applied to corpora in new domains, without the need for exhaustive tuning or modification, whilst retaining competitive levels of performance. We have enhanced our state-of-the-art event extraction system, EventMine, to alleviate the need for task-specific tuning. Task-specific details are specified in a configuration file, while extensive task-specific parameter tuning is avoided through the integration of a weighting method, a covariate shift method, and their combination. The task-specific configuration and weighting method have been employed within the context of two different sub-tasks of BioNLP shared task 2013, i.e. Cancer Genetics (CG) and Pathway Curation (PC), removing the need to modify the system specifically for each task. With minimal task specific configuration and tuning, EventMine achieved the 1st place in the PC task, and 2nd in the CG, achieving the highest recall for both tasks. The system has been further enhanced following the shared task by incorporating the covariate shift method and entity generalisations based on the task definitions, leading to further performance improvements. We have shown that it is possible to apply a state-of-the-art event extraction system to new tasks with high levels of performance, without having to modify the system internally. Both covariate shift and weighting methods are useful in facilitating the production of high recall systems. These methods and their combination can adapt a model to the target data with no deep tuning and little manual configuration.

Self-assembling software generator

DOEpatents

Bouchard, Ann M [Albuquerque, NM; Osbourn, Gordon C [Albuquerque, NM

2011-11-25

A technique to generate an executable task includes inspecting a task specification data structure to determine what software entities are to be generated to create the executable task, inspecting the task specification data structure to determine how the software entities will be linked after generating the software entities, inspecting the task specification data structure to determine logic to be executed by the software entities, and generating the software entities to create the executable task.

Liquid Metering Centrifuge Sticks (LMCS): A Centrifugal Approach to Metering Known Sample Volumes for Colorimetric Solid Phase Extraction (C-SPE)

NASA Technical Reports Server (NTRS)

Gazda, Daniel B.; Schultz, John R.; Clarke, Mark S.

2007-01-01

Phase separation is one of the most significant obstacles encountered during the development of analytical methods for water quality monitoring in spacecraft environments. Removing air bubbles from water samples prior to analysis is a routine task on earth; however, in the absence of gravity, this routine task becomes extremely difficult. This paper details the development and initial ground testing of liquid metering centrifuge sticks (LMCS), devices designed to collect and meter a known volume of bubble-free water in microgravity. The LMCS uses centrifugal force to eliminate entrapped air and reproducibly meter liquid sample volumes for analysis with Colorimetric Solid Phase Extraction (C-SPE). C-SPE is a sorption-spectrophotometric platform that is being developed as a potential spacecraft water quality monitoring system. C-SPE utilizes solid phase extraction membranes impregnated with analyte-specific colorimetric reagents to concentrate and complex target analytes in spacecraft water samples. The mass of analyte extracted from the water sample is determined using diffuse reflectance (DR) data collected from the membrane surface and an analyte-specific calibration curve. The analyte concentration can then be calculated from the mass of extracted analyte and the volume of the sample analyzed. Previous flight experiments conducted in microgravity conditions aboard the NASA KC-135 aircraft demonstrated that the inability to collect and meter a known volume of water using a syringe was a limiting factor in the accuracy of C-SPE measurements. Herein, results obtained from ground based C-SPE experiments using ionic silver as a test analyte and either the LMCS or syringes for sample metering are compared to evaluate the performance of the LMCS. These results indicate very good agreement between the two sample metering methods and clearly illustrate the potential of utilizing centrifugal forces to achieve phase separation and metering of water samples in microgravity.

Sodiated Sugar Structures: Cryogenic Ion Vibrational Spectroscopy of Na^+(GLUCOSE) Adducts

NASA Astrophysics Data System (ADS)

Voss, Jonathan; Kregel, Steven J.; Fischer, Kaitlyn C.; Garand, Etienne

2017-06-01

The recent discovery that ionic liquids help facilitate the dissolution of cellulose has renewed interest in understanding how ionic species interact with carbohydrates. Here we present infrared spectra in the 2800 - 3800 \\wn range of gas-phase mass-selected Na^+(Glucose) adducts. These adducts are further probed with IR-dip spectroscopy to yield conformer specific spectra of at least seven unique species. The relative abundances of conformers show that gas-phase interconversion barriers are sufficiently high to preserve the solution-phase populations. Additionally, our results demonstrate that mM concentrations of NaCl do not strongly perturb the anomeric ratio of glucose in solution.

International Conference on the Physics of Electronic and Atomic Collisions (14th) Held in Palo Alto, California on 24-30 July 1985 (Electronic and Atomic Collisions. Invited Papers)

DTIC Science & Technology

1985-07-30

OA 3’, one of the cases studied by Lohmann et al(2 ). The new feature in their measurement is that they normalize their cross section by an...dynamic behav- ior of neutral and ionic clusters[lO]. In the case of ionic clusters there have been already extensive studies on their stability and...The specific cases studied so far on an ab initio level (e + F2 [12], e + N2 [13], e + H2 [14]) indicate that nonlocal effects are generally important

Structure of the Stern layer in Phospholipid Systems

NASA Astrophysics Data System (ADS)

Vangaveti, Sweta; Travesset, Alex

2011-03-01

The structure of the Stern layer in Phospholipid Systems results from a subtle competition of salt concentration, ionic valence, specific ionic-phospolipid interactions and pH. It becomes very challenging to develop a rigorous theory that encompasses all these effects, yet its understanding is extremely relevant for both model and biological systems, as the structure of the Stern layer determines the interactions of phospholipids with proteins or electrostatic phase separation (rafts). In this talk we will present our theoretical model for the Stern Layer and discuss how all these effects are included. Particularly emphasis is made to Phosphoinositides and Phosphatidic acid. This work is supported by grant NSF DMR-0748475.

Controlled Synthesis of Polyions of Heavy Main-Group Elements in Ionic Liquids

PubMed Central

Groh, Matthias F.; Wolff, Alexander; Grasser, Matthias A.; Ruck, Michael

2016-01-01

Ionic liquids (ILs) have been proven to be valuable reaction media for the synthesis of inorganic materials among an abundance of other applications in different fields of chemistry. Up to now, the syntheses have remained mostly “black boxes”; and researchers have to resort to trial-and-error in order to establish a new synthetic route to a specific compound. This review comprises decisive reaction parameters and techniques for the directed synthesis of polyions of heavy main-group elements (fourth period and beyond) in ILs. Several families of compounds are presented ranging from polyhalides over carbonyl complexes and selenidostannates to homo and heteropolycations. PMID:27598123

Multilaboratory study of the shifts in the IEP of anatase at high ionic strengths.

PubMed

Kosmulski, Marek; Dukhin, Andrei S; Priester, Torsten; Rosenholm, Jarl B

2003-07-01

The zeta-potentials of anatase at pH 2-11 in 0.1, 0.3, 0.5, and 1 moldm(-3) NaI were studied using the DT 1200 in three laboratories. At [NaI]=1 moldm(-3) the zeta-potentials were positive over the entire pH range. The previously observed tendency of the isoelectric point of anatase to shift to high pH at high ionic strength (M. Kosmulski, J.B. Rosenholm, J. Phys. Chem. 100 (1996) 11681) and the salt specificity of this effect were confirmed. The zeta-potentials obtained in different laboratories using DT 1200 are consistent within 3 mV.

Surface layering and melting in an ionic liquid studied by resonant soft X-ray reflectivity

PubMed Central

Mezger, Markus; Ocko, Benjamin M.; Reichert, Harald; Deutsch, Moshe

2013-01-01

The molecular-scale structure of the ionic liquid [C18mim]+[FAP]− near its free surface was studied by complementary methods. X-ray absorption spectroscopy and resonant soft X-ray reflectivity revealed a depth-decaying near-surface layering. Element-specific interfacial profiles were extracted with submolecular resolution from energy-dependent soft X-ray reflectivity data. Temperature-dependent hard X-ray reflectivity, small- and wide-angle X-ray scattering, and infrared spectroscopy uncovered an intriguing melting mechanism for the layered region, where alkyl chain melting drove a negative thermal expansion of the surface layer spacing. PMID:23431181

High-resolution mapping of molecules in an ionic liquid via scanning transmission electron microscopy.

PubMed

Miyata, Tomohiro; Mizoguchi, Teruyasu

2018-03-01

Understanding structures and spatial distributions of molecules in liquid phases is crucial for the control of liquid properties and to develop efficient liquid-phase processes. Here, real-space mapping of molecular distributions in a liquid was performed. Specifically, the ionic liquid 1-Ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (C2mimTFSI) was imaged using atomic-resolution scanning transmission electron microscopy. Simulations revealed network-like bright regions in the images that were attributed to the TFSI- anion, with minimal contributions from the C2mim+ cation. Simple visualization of the TFSI- distribution in the liquid sample was achieved by binarizing the experimental image.

K2P TASK-2 and KCNQ1-KCNE3 K+ channels are major players contributing to intestinal anion and fluid secretion.

PubMed

Julio-Kalajzić, Francisca; Villanueva, Sandra; Burgos, Johanna; Ojeda, Margarita; Cid, L Pablo; Jentsch, Thomas J; Sepúlveda, Francisco V

2018-02-01

K + channels are important in intestinal epithelium as they ensure the ionic homeostasis and electrical potential of epithelial cells during anion and fluid secretion. Intestinal epithelium cAMP-activated anion secretion depends on the activity of the (also cAMP dependent) KCNQ1-KCNE3 K + channel, but the secretory process survives after genetic inactivation of the K + channel in the mouse. Here we use double mutant mice to investigate which alternative K + channels come into action to compensate for the absence of KCNQ1-KCNE3 K + channels. Our data establish that whilst Ca 2+ -activated K Ca 3.1 channels are not involved, K 2P two-pore domain TASK-2 K + channels are major players providing an alternative conductance to sustain the intestinal secretory process. Work with double mutant mice lacking both TASK-2 and KCNQ1-KCNE3 channels nevertheless points to yet-unidentified K + channels that contribute to the robustness of the cAMP-activated anion secretion process. Anion and fluid secretion across the intestinal epithelium, a process altered in cystic fibrosis and secretory diarrhoea, is mediated by cAMP-activated CFTR Cl - channels and requires the simultaneous activity of basolateral K + channels to maintain cellular ionic homeostasis and membrane potential. This function is fulfilled by the cAMP-activated K + channel formed by the association of pore-forming KCNQ1 with its obligatory KCNE3 β-subunit. Studies using mice show sizeable cAMP-activated intestinal anion secretion in the absence of either KCNQ1 or KCNE3 suggesting that an alternative K + conductance must compensate for the loss of KCNQ1-KCNE3 activity. We used double mutant mouse and pharmacological approaches to identify such a conductance. Ca 2+ -dependent anion secretion can also be supported by Ca 2+ -dependent K Ca 3.1 channels after independent CFTR activation, but cAMP-dependent anion secretion is not further decreased in the combined absence of K Ca 3.1 and KCNQ1-KCNE3 K + channel activity. We show that the K 2P K + channel TASK-2 is expressed in the epithelium of the small and large intestine. Tetrapentylammonium, a TASK-2 inhibitor, abolishes anion secretory current remaining in the absence of KCNQ1-KCNE3 activity. A double mutant mouse lacking both KCNQ1-KCNE3 and TASK-2 showed a much reduced cAMP-mediated anion secretion compared to that observed in the single KCNQ1-KCNE3 deficient mouse. We conclude that KCNQ1-KCNE3 and TASK-2 play major roles in the intestinal anion and fluid secretory phenotype. The persistence of an, admittedly reduced, secretory activity in the absence of these two conductances suggests that further additional K + channel(s) as yet unidentified contribute to the robustness of the intestinal anion secretory process. © 2017 The Authors. The Journal of Physiology © 2017 The Physiological Society.

Mesopore- and Macropore-Dominant Nitrogen-Doped Hierarchically Porous Carbons for High-Energy and Ultrafast Supercapacitors in Non-Aqueous Electrolytes.

PubMed

Shao, Rong; Niu, Jin; Liang, Jingjing; Liu, Mengyue; Zhang, Zhengping; Dou, Meiling; Huang, Yaqin; Wang, Feng

2017-12-13

Non-aqueous electrolytes (e.g., organic and ionic liquid electrolytes) can undergo high working voltage to improve the energy densities of supercapacitors. However, the large ion sizes, high viscosities, and low ionic conductivities of organic and ionic liquid electrolytes tend to cause the low specific capacitances, poor rate, and cycling performance of supercapacitors based on conventional micropore-dominant activated carbon electrodes, limiting their practical applications. Herein, we propose an effective strategy to simultaneously obtain high power and energy densities in non-aqueous electrolytes via using a cattle bone-derived porous carbon as an electrode material. Because of the unique co-activation of KOH and hydroxyapatite (HA) within the cattle bone, nitrogen-doped hierarchically porous carbon (referred to as NHPC-HA/KOH) is obtained and possesses a mesopore- and macropore-dominant porosity with an ultrahigh specific surface area (2203 m 2 g -1 ) of meso- and macropores. The NHPC-HA/KOH electrodes exhibit superior performance with specific capacitances of 224 and 240 F g -1 at 5 A g -1 in 1.0 M TEABF 4 /AN and neat EMIMBF 4 electrolyte, respectively. The symmetric supercapacitor using NHPC-HA/KOH electrodes can deliver integrated high energy and power properties (48.6 W h kg -1 at 3.13 kW kg -1 in 1.0 M TEABF 4 /AN and 75 W h kg -1 at 3.75 kW kg -1 in neat EMIMBF 4 ), as well as superior cycling performance (over 89% of the initial capacitance after 10 000 cycles at 10 A g -1 ).

Evaluating contribution of ionic, osmotic and oxidative stress components towards salinity tolerance in barley

PubMed Central

2014-01-01

Background Salinity tolerance is a physiologically multi-faceted trait attributed to multiple mechanisms. Three barley (Hordeum vulgare) varieties contrasting in their salinity tolerance were used to assess the relative contribution of ionic, osmotic and oxidative stress components towards overall salinity stress tolerance in this species, both at the whole-plant and cellular levels. In addition, transcriptional changes in the gene expression profile were studied for key genes mediating plant ionic and oxidative homeostasis (NHX; RBOH; SOD; AHA and GORK), to compare a contribution of transcriptional and post-translational factors towards the specific components of salinity tolerance. Results Our major findings are two-fold. First, plant tissue tolerance was a dominating component that has determined the overall plant responses to salinity, with root K+ retention ability and reduced sensitivity to stress-induced hydroxyl radical production being the main contributing tolerance mechanisms. Second, it was not possible to infer which cultivars were salinity tolerant based solely on expression profiling of candidate genes at one specific time point. For the genes studied and the time point selected that transcriptional changes in the expression of these specific genes had a small role for barley’s adaptive responses to salinity. Conclusions For better tissue tolerance, sodium sequestration, K+ retention and resistance to oxidative stress all appeared to be crucial. Because these traits are highly interrelated, it is suggested that a major progress in crop breeding for salinity tolerance can be achieved only if these complementary traits are targeted at the same time. This study also highlights the essentiality of post translational modifications in plant adaptive responses to salinity. PMID:24774965

Comparing two tetraalkylammonium ionic liquids. II. Phase transitions

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

Lima, Thamires A.; Paschoal, Vitor H.; Faria, Luiz F. O.

Phase transitions of the ionic liquids n-butyl-trimethylammonium bis(trifluoromethanesulfonyl)imide, [N{sub 1114}][NTf{sub 2}], and methyl-tributylammonium bis(trifluoromethanesulfonyl)imide, [N{sub 1444}][NTf{sub 2}], were investigated by differential scanning calorimetry (DSC), X-ray diffraction (XRD) measurements, and Raman spectroscopy. XRD and Raman spectra were obtained as a function of temperature at atmospheric pressure, and also under high pressure at room temperature using a diamond anvil cell (DAC). [N{sub 1444}][NTf{sub 2}] experiences glass transition at low temperature, whereas [N{sub 1114}][NTf{sub 2}] crystallizes or not depending on the cooling rate. Both the ionic liquids exhibit glass transition under high pressure. XRD and low-frequency Raman spectra provide a consistent physical picturemore » of structural ordering-disordering accompanying the thermal events of crystallization, glass transition, cold crystallization, pre-melting, and melting. Raman spectra in the high-frequency range of some specific cation and anion normal modes reveal conformational changes of the molecular structures along phase transitions.« less

Improved Performance of Ionic Liquid Supercapacitors by using Tetracyanoborate Anions.

PubMed

Martins, Vitor L; Rennie, Anthony J R; Sanchez-Ramirez, Nedher; Torresi, Roberto M; Hall, Peter J

2018-02-01

Supercapacitors are energy storage devices designed to operate at higher power densities than conventional batteries, but their energy density is still too low for many applications. Efforts are made to design new electrolytes with wider electrochemical windows than aqueous or conventional organic electrolytes in order to increase energy density. Ionic liquids (ILs) with wide electrochemical stability windows are excellent candidates to be employed as supercapacitor electrolytes. ILs containing tetracyanoborate anions [B(CN) 4 ] offer wider electrochemical stability than conventional electrolytes and maintain a high ionic conductivity (6.9 mS cm -1 ). Herein, we report the use of ILs containing the [B(CN) 4 ] anion for such an application. They presented a high maximum operating voltage of 3.7 V, and two-electrode devices demonstrate high specific capacitances even when operating at relatively high rates (ca. 20 F g -1 @ 15 A g -1 ). This supercapacitor stored more energy and operated at a higher power at all rates studied when compared with cells using a commonly studied ILs.

Use of ionic liquids as stationary phases in hyphenated gas chromatography techniques.

PubMed

Ragonese, Carla; Sciarrone, Danilo; Tranchida, Peter Quinto; Dugo, Paola; Mondello, Luigi

2012-09-14

In the past decades a consistent number of ionic liquids have been specifically synthesized and evaluated as stationary phase in gas chromatography. Ionic liquid, also defined as "molten salts", are a class of organic non-molecular solvents liquid at room temperature (RTILs) that satisfy most of the requirements of a GC stationary phase, among which a high viscosity, the possibility to tune the selectivity (by changing the cation-anion combination) and a high thermal stability. The choice of the proper stationary phase plays a key role in the improvement/optimization of a GC method, and although the use of IL as stationary phases is still not well-established, the general interest in their applications has greatly increased, thanks to their particular properties. The present contribution provides an overview on recent evaluations and applications of IL stationary phases, focusing in particular on the use of these novel tools in hyphenated GC-based techniques. Copyright © 2012 Elsevier B.V. All rights reserved.

Combinatorial ligand libraries as a two-dimensional method for proteome analysis.

PubMed

Santucci, Laura; Candiano, Giovanni; Petretto, Andrea; Lavarello, Chiara; Bruschi, Maurizio; Ghiggeri, Gian Marco; Citterio, Attilio; Righetti, Pier Giorgio

2013-07-05

The present report tries to assess the possibility of performing capture of proteomes via combinatorial peptide ligand libraries (CPLL) in a two-dimensional (2D) mode, i.e. via orthogonal complementarity in the capture phase. To that aim, serum proteins are captured at physiological pH either at low ionic strength (25mM NaCl) or at high concentrations of lyotropic salts of the Hofmeister series (1M ammonium sulphate) favouring hydrophobic interaction. Indeed such 2D mechanisms seems to be operative, since 52% of the captured proteins are common to the two capture modes, 20% are specific only of the "ionic" interaction mode and 28% are found only in the "hydrophobically" driven interaction. As an additional bonus, losses of protein species from the initial sample, one of the major drawbacks of CPLLs, are diminished to about 5% and are found only in the ionic capture, whereas the hydrophobically engendered capture is loss-free. Copyright © 2013 Elsevier B.V. All rights reserved.

Enzymatic hybridization of α-lipoic acid with bioactive compounds in ionic solvents.

PubMed

Papadopoulou, Athena A; Katsoura, Maria H; Chatzikonstantinou, Alexandra; Kyriakou, Eleni; Polydera, Angeliki C; Tzakos, Andreas G; Stamatis, Haralambos

2013-05-01

The lipase-catalyzed molecular hybridization of α-lipoic acid (LA) with bioactive compounds pyridoxine, tyrosol and tyramine was performed in ionic solvents and deep eutectic solvents. The biocatalytic reactions were catalyzed by Candida antarctica lipase B immobilized onto various functionalized multi-walled carbon nanotubes (f-CNTs-CaLB), as well as by commercial Novozym 435. The use of f-CNTs-CaLB leads, in most cases, to higher conversion yields as compared to Novozym 435. The nature and ion composition of ionic solvents affect the performance of the biocatalytic process. The highest conversion yield was observed in (mtoa)NTf2. The high enzyme stability and the relatively low solubility of substrates in specific media account for the improved biocatalytic synthesis of molecular hybrids of LA. Principal component analysis was used to screen for potential lipoxygenase inhibitors. In vitro studies showed that the synthesized compounds exhibit up to 10-fold increased inhibitory activity on lipoxygenase mediated lipid peroxidation as compared to parent molecules. Copyright © 2013 Elsevier Ltd. All rights reserved.

Aqueous ionic liquids and their effects on protein structures: an overview on recent theoretical and experimental results

NASA Astrophysics Data System (ADS)

Smiatek, Jens

2017-06-01

Ionic liquids (ILs) are used in a variety of technological and biological applications. Recent experimental and simulation results reveal the influence of aqueous ionic liquids on the stability of protein and enzyme structures. Depending on different parameters like the concentration and the ion composition, one can observe distinct stabilization or denaturation mechanisms for various ILs. In this review, we summarize the main findings and discuss the implications with regard to molecular theories of solutions and specific ion effects. A preferential binding model is introduced in order to discuss protein-IL effects from a statistical mechanics perspective. The value of the preferential binding coefficient determines the strength of the ion influence and indicates a shift of the chemical equilibrium either to the native or the denatured state of the protein. We highlight the role of water in order to explain the self-association behavior of the IL species and discuss recent experimental and simulation results in the light of the observed binding effects.

Evaluation of Carbon Composite Overwrap Pressure Vessels Fabricated Using Ionic Liquid Epoxies Project

NASA Technical Reports Server (NTRS)

Grugel, Richard

2015-01-01

The intent of the work proposed here is to ascertain the viability of ionic liquid (IL) epoxy based carbon fiber composites for use as storage tanks at cryogenic temperatures. This IL epoxy has been specifically developed to address composite cryogenic tank challenges associated with achieving NASA's in-space propulsion and exploration goals. Our initial work showed that an unadulterated ionic liquid (IL) carbon-fiber composite exhibited improved properties over an optimized commercial product at cryogenic temperatures. Subsequent investigative work has significantly improved the IL epoxy and our first carbon-fiber Composite Overwrap Pressure Vessel (COPV) was successfully fabricated. Here additional COPVs, using a further improved IL epoxy, will be fabricated and pressure tested at cryogenic temperatures with the results rigorously analyzed. Investigation of the IL composite for lower pressure liner-less cryogenic tank applications will also be initiated. It is expected that the current Technology Readiness Level (TRL) will be raised from about TRL 3 to TRL 5 where unambiguous predictions for subsequent development/testing can be made.

Soil-Water Characteristic Curves of Red Clay treated by Ionic Soil Stabilizer

NASA Astrophysics Data System (ADS)

Cui, D.; Xiang, W.

2009-12-01

The relationship of red clay particle with water is an important factor to produce geological disaster and environmental damage. In order to reduce the role of adsorbed water of red clay in WuHan, Ionic Soil Stabilizer (ISS) was used to treat the red clay. Soil Moisture Equipment made in U.S.A was used to measure soil-water characteristic curve of red clay both in natural and stabilized conditions in the suction range of 0-500kPa. The SWCC results were used to interpret the red clay behavior due to stabilizer treatment. In addition, relationship were compared between the basic soil and stabilizer properties such as water content, dry density, liquid limit, plastic limit, moisture absorption rate and stabilizer dosages. The analysis showed that the particle density and specific surface area increase, the dehydration rate slows and the thickness of water film thins after treatment with Ionic Soil Stabilizer. After treatment with the ISS, the geological disasters caused by the adsorbed water of red clay can be effectively inhibited.

Preparation of ionic-crosslinked chitosan-based gel beads and effect of reaction conditions on drug release behaviors.

PubMed

Chen, Shilan; Liu, Mingzhu; Jin, Shuping; Wang, Bin

2008-02-12

Drug-loaded chitosan (CS) beads were prepared under simple and mild condition using trisodium citrate as ionic crosslinker. The beads were further coated with poly(methacrylic acid) (PMAA) by dipping the beads in PMAA aqueous solution. The surface and cross-section morphology of these beads were observed by scanning electron microscopy and the observation showed that the coating beads had core-shell structure. In vitro release of model drug from these beads obtained under different reaction conditions was investigated in buffer medium (pH 1.8). The results showed that the rapid drug release was restrained by PMAA coating and the optimum conditions for preparing CS-based drug-loaded beads were decided through the effect of reaction conditions on the drug release behaviors. In addition, the drug release mechanism of CS-based drug-loaded beads was analyzed by Peppa's potential equation. According to this study, the ionic-crosslinked CS beads coated by PMAA could serve as suitable candidate for drug site-specific carrier in stomach.

Effect of surfactants on sorption of atrazine by soil

NASA Astrophysics Data System (ADS)

Abu-Zreig, Majed; Rudra, R. P.; Dickinson, W. T.; Evans, L. J.

1999-03-01

This study investigates the effect of synthetic wastewater containing surfactants on the sorption of atrazine using an equilibrium batch technique. Laboratory experiments were conducted on three soils with two non-ionic (Rexol and Rexonic) surfactants and one anionic (Sulphonic) surfactant, specifically manufactured for the detergent industry. Four sets of experiments were conducted to examine the influence of surfactants on the equilibrium time of atrazine sorption, to explore the effect of surfactant concentration, pH and type of surfactant on the amount of atrazine sorbed and to determine sorption isotherms of atrazine in the presence of surfactants. The results indicate that the application of Sulphonic results in dramatic increase in the adsorption of atrazine on to soils, the increase being directly proportional to the concentration of the surfactant. Application of the Sulphonic surfactants with a concentration of 3000 mg/l can result in a significant increase in Kd values of atrazine for loam and sandy loam soils. On the other hand, the effect of non-ionic surfactants depends on their concentration. Generally, non-ionic surfactants can result in a slight increase in atrazine sorption at high concentration, an exception being Rexol on sandy loam soil. At low concentrations, non-ionic surfactants have shown a tendency to decrease atrazine sorption.

Synthesis of thermo-responsive bovine hemoglobin imprinted nanoparticles by combining ionic liquid immobilization with aqueous precipitation polymerization.

PubMed

Wang, Yongmei; Yang, Chongchong; Sun, Yan; Qiu, Fengtao; Xiang, Yang; Fu, Guoqi

2018-02-01

Surface molecular imprinting over functionalized nanoparticles has proved to be an effective approach for construction of artificial nanomaterials for protein recognition. Herein, we report a strategy for synthesis of core-shell protein-imprinted nanoparticles by the functionalization of nano-cores with ionic liquids followed by aqueous precipitation polymerization to build thermo-responsive imprinted polymer nano-shells. The immobilized ionic liquids can form multiple interactions with the protein template. The polymerization process can produce thermo-reversible physical crosslinks, which are advantageous to enhancing imprinting and facilitating template removal. With bovine hemoglobin as a model template, the imprinted nanoparticles showed temperature-sensitivity in both dispersion behaviors and rebinding capacities. Compared with the ionic-liquid-modified core nanoparticles, the imprinted particles exhibited greatly increased selectivity and two orders of magnitude higher binding affinity for the template protein. The imprinted nanoparticles achieved relatively high imprinting factor up to 5.0 and specific rebinding capacity of 67.7 mg/g, respectively. These nanoparticles also demonstrated rapid rebinding kinetics and good reproducibility after five cycles of adsorption-regeneration. Therefore, the presented approach may be viable for the fabrication of high-performance protein-imprinted nanoparticles with temperature sensitivity. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enhancing the performance of green solid-state electric double-layer capacitor incorporated with fumed silica nanoparticles

NASA Astrophysics Data System (ADS)

Chong, Mee Yoke; Numan, Arshid; Liew, Chiam-Wen; Ng, H. M.; Ramesh, K.; Ramesh, S.

2018-06-01

Solid polymer electrolyte (SPE) based on fumed silica nanoparticles as nanofillers, hydroxylethyl cellulose (HEC) as host polymer, magnesium trifluoromethanesulfonate salt and 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ionic liquid is prepared by solution casting technique. The ionic conductivity, interactions of adsorbed ions on the host polymer, structural crystallinity and thermal stability are evaluated by electrochemical impedance spectroscopy (EIS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA), respectively. Ionic conductivity studies at room temperature reveals that the SPE with 2 wt. % of fumed silica nanoparticles gives the highest conductivity compared to its counterpart. The XRD and FTIR studies confirm the dissolution of salt, ionic liquid and successful incorporation of fumed silica nanoparticles with host polymer. In order to examine the performance of SPEs, electric double-layer capacitor (EDLC) are fabricated by using activated carbon electrodes. EDLC studies demonstrate that SPE incorporated with 2 wt. % fumed silica nanoparticles gives high specific capacitance (25.0 F/g) at a scan rate of 5 mV/s compared to SPE without fumed silica. Additionally, it is able to withstand 71.3% of capacitance from its initial capacitance value over 1600 cycles at a current density of 0.4 A/g.

Through-plane conductivities of membranes for nonaqueous redox flow batteries

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

Anderson, Travis Mark; Small, Leo J.; Pratt, III, Harry D.

In this study, nonaqueous redox flow batteries (RFB) leverage nonaqueous solvents to enable higher operating voltages compared to their aqueous counterparts. Most commercial components for flow batteries, however, are designed for aqueous use. One critical component, the ion-selective membrane, provides ionic conductance between electrodes while preventing crossover of electroactive species. Here we evaluate the area-specific conductances and through-plane conductivities of commercially available microporous separators (Celgard 2400, 2500) and anion exchange membranes (Neosepta AFX, Neosepta AHA, Fumasep FAP-450, Fumasep FAP-PK) soaked in acetonitrile, propylene carbonate, or two imidazolium-based ionic liquids. Fumasep membranes combined with acetonitrile-based electrolyte solutions provided the highest conductancemore » values and conductivities by far. When tested in ionic liquids, all anion exchange membranes displayed conductivities greater than those of the Celgard microporous separators, though the separators’ decreased thickness-enabled conductances on par with the most conductive anion exchange membranes. Ionic conductivity is not the only consideration when choosing an anion exchange membrane; testing of FAP-450 and FAP-PK membranes in a nonaqueous RFB demonstrated that the increased mechanical stability of PEEK-supported FAP-PK minimized swelling, in turn decreasing solvent mediated crossover and enabling greater electrochemical yields (40% vs. 4%) and Coulombic efficiencies (94% vs. 90%) compared to the unsupported, higher conductance FAP-450.« less

Through-plane conductivities of membranes for nonaqueous redox flow batteries

DOE PAGES

Anderson, Travis Mark; Small, Leo J.; Pratt, III, Harry D.; ...

2015-08-13

In this study, nonaqueous redox flow batteries (RFB) leverage nonaqueous solvents to enable higher operating voltages compared to their aqueous counterparts. Most commercial components for flow batteries, however, are designed for aqueous use. One critical component, the ion-selective membrane, provides ionic conductance between electrodes while preventing crossover of electroactive species. Here we evaluate the area-specific conductances and through-plane conductivities of commercially available microporous separators (Celgard 2400, 2500) and anion exchange membranes (Neosepta AFX, Neosepta AHA, Fumasep FAP-450, Fumasep FAP-PK) soaked in acetonitrile, propylene carbonate, or two imidazolium-based ionic liquids. Fumasep membranes combined with acetonitrile-based electrolyte solutions provided the highest conductancemore » values and conductivities by far. When tested in ionic liquids, all anion exchange membranes displayed conductivities greater than those of the Celgard microporous separators, though the separators’ decreased thickness-enabled conductances on par with the most conductive anion exchange membranes. Ionic conductivity is not the only consideration when choosing an anion exchange membrane; testing of FAP-450 and FAP-PK membranes in a nonaqueous RFB demonstrated that the increased mechanical stability of PEEK-supported FAP-PK minimized swelling, in turn decreasing solvent mediated crossover and enabling greater electrochemical yields (40% vs. 4%) and Coulombic efficiencies (94% vs. 90%) compared to the unsupported, higher conductance FAP-450.« less

The Role of Ionic Interactions in the Adherence of the S. epidermidis Adhesin SdrF to Prosthetic Material

PubMed Central

Toba, Faustino A.; Visai, Livia; Trivedi, Sheetal; Lowy, Franklin D.

2012-01-01

Staphylococcus epidermidis infections are common complications of prosthetic device implantation. SdrF, a surface protein, appears to play a critical role in the initial colonization step by adhering to type I collagen and Dacron™. The role of ionic interactions in S. epidermidis adherence to prosthetic material was examined. SdrF was cloned and expressed in Lactococcus lactis. The effect of pH, cation concentration and detergents on adherence to different types of plastic surfaces was assessed by crystal violet staining and bacterial cell counting. SdrF, in contrast with controls and other S. epidermidis surface proteins, bound to hydrophobic materials such as polystyrene. Binding was an ionic interaction and was affected by surface charge of the plastic, pH and cation concentration. Adherence of the SdrF construct was increased to positively charged plastics and was reduced by increasing concentrations of Ca2+ and Na+. Binding was optimal at pH 7.4. Kinetic studies demonstrated that the SdrF B domain, as well as one of the B subdomains was sufficient to mediate binding. The SdrF construct also bound more avidly to Goretex™ than the lacotococcal control. SdrF is a multifunctional protein that contributes to prosthetic devices infections by ionic, as well as specific receptor-ligand interactions. PMID:23039791

The role of electrostatic interactions in protease surface diffusion and the consequence for interfacial biocatalysis.

PubMed

Feller, Bob E; Kellis, James T; Cascão-Pereira, Luis G; Robertson, Channing R; Frank, Curtis W

2010-12-21

This study examines the influence of electrostatic interactions on enzyme surface diffusion and the contribution of diffusion to interfacial biocatalysis. Surface diffusion, adsorption, and reaction were investigated on an immobilized bovine serum albumin (BSA) multilayer substrate over a range of solution ionic strength values. Interfacial charge of the enzyme and substrate surface was maintained by performing the measurements at a fixed pH; therefore, electrostatic interactions were manipulated by changing the ionic strength. The interfacial processes were investigated using a combination of techniques: fluorescence recovery after photobleaching, surface plasmon resonance, and surface plasmon fluorescence spectroscopy. We used an enzyme charge ladder with a net charge ranging from -2 to +4 with respect to the parent to systematically probe the contribution of electrostatics in interfacial enzyme biocatalysis on a charged substrate. The correlation between reaction rate and adsorption was determined for each charge variant within the ladder, each of which displayed a maximum rate at an intermediate surface concentration. Both the maximum reaction rate and adsorption value at which this maximum rate occurs increased in magnitude for the more positive variants. In addition, the specific enzyme activity increased as the level of adsorption decreased, and for the lowest adsorption values, the specific enzyme activity was enhanced compared to the trend at higher surface concentrations. At a fixed level of adsorption, the specific enzyme activity increased with positive enzyme charge; however, this effect offers diminishing returns as the enzyme becomes more highly charged. We examined the effect of electrostatic interactions on surface diffusion. As the binding affinity was reduced by increasing the solution ionic strength, thus weakening electrostatic interaction, the rate of surface diffusion increased considerably. The enhancement in specific activity achieved at the lowest adsorption values is explained by the substantial rise in surface diffusion at high ionic strength due to decreased interactions with the surface. Overall, knowledge of the electrostatic interactions can be used to control surface parameters such as surface concentration and surface diffusion, which intimately correlate with surface biocatalysis. We propose that the maximum reaction rate results from a balance between adsorption and surface diffusion. The above finding suggests enzyme engineering and process design strategies for improving interfacial biocatalysis in industrial, pharmaceutical, and food applications.

Adaptable, high recall, event extraction system with minimal configuration

PubMed Central

2015-01-01

Background Biomedical event extraction has been a major focus of biomedical natural language processing (BioNLP) research since the first BioNLP shared task was held in 2009. Accordingly, a large number of event extraction systems have been developed. Most such systems, however, have been developed for specific tasks and/or incorporated task specific settings, making their application to new corpora and tasks problematic without modification of the systems themselves. There is thus a need for event extraction systems that can achieve high levels of accuracy when applied to corpora in new domains, without the need for exhaustive tuning or modification, whilst retaining competitive levels of performance. Results We have enhanced our state-of-the-art event extraction system, EventMine, to alleviate the need for task-specific tuning. Task-specific details are specified in a configuration file, while extensive task-specific parameter tuning is avoided through the integration of a weighting method, a covariate shift method, and their combination. The task-specific configuration and weighting method have been employed within the context of two different sub-tasks of BioNLP shared task 2013, i.e. Cancer Genetics (CG) and Pathway Curation (PC), removing the need to modify the system specifically for each task. With minimal task specific configuration and tuning, EventMine achieved the 1st place in the PC task, and 2nd in the CG, achieving the highest recall for both tasks. The system has been further enhanced following the shared task by incorporating the covariate shift method and entity generalisations based on the task definitions, leading to further performance improvements. Conclusions We have shown that it is possible to apply a state-of-the-art event extraction system to new tasks with high levels of performance, without having to modify the system internally. Both covariate shift and weighting methods are useful in facilitating the production of high recall systems. These methods and their combination can adapt a model to the target data with no deep tuning and little manual configuration. PMID:26201408

Comparative Cognitive Task Analysis

DTIC Science & Technology

2007-01-01

is to perform a task analyses to determine how people operate in a specific domain on a specific task. Cognitive Task Analysis (CTA) is a set of...accomplish a task. In this chapter, we build on CTA methods by suggesting that comparative cognitive task analysis (C2TA) can help solve the aforementioned

ARS-Media for Excel: A Spreadsheet Tool for Calculating Media Recipes Based on Ion-Specific Constraints

PubMed Central

Niedz, Randall P.

2016-01-01

ARS-Media for Excel is an ion solution calculator that uses “Microsoft Excel” to generate recipes of salts for complex ion mixtures specified by the user. Generating salt combinations (recipes) that result in pre-specified target ion values is a linear programming problem. Excel’s Solver add-on solves the linear programming equation to generate a recipe. Calculating a mixture of salts to generate exact solutions of complex ionic mixtures is required for at least 2 types of problems– 1) formulating relevant ecological/biological ionic solutions such as those from a specific lake, soil, cell, tissue, or organ and, 2) designing ion confounding-free experiments to determine ion-specific effects where ions are treated as statistical factors. Using ARS-Media for Excel to solve these two problems is illustrated by 1) exactly reconstructing a soil solution representative of a loamy agricultural soil and, 2) constructing an ion-based experiment to determine the effects of substituting Na+ for K+ on the growth of a Valencia sweet orange nonembryogenic cell line. PMID:27812202

ARS-Media for Excel: A Spreadsheet Tool for Calculating Media Recipes Based on Ion-Specific Constraints.

PubMed

Niedz, Randall P

2016-01-01

ARS-Media for Excel is an ion solution calculator that uses "Microsoft Excel" to generate recipes of salts for complex ion mixtures specified by the user. Generating salt combinations (recipes) that result in pre-specified target ion values is a linear programming problem. Excel's Solver add-on solves the linear programming equation to generate a recipe. Calculating a mixture of salts to generate exact solutions of complex ionic mixtures is required for at least 2 types of problems- 1) formulating relevant ecological/biological ionic solutions such as those from a specific lake, soil, cell, tissue, or organ and, 2) designing ion confounding-free experiments to determine ion-specific effects where ions are treated as statistical factors. Using ARS-Media for Excel to solve these two problems is illustrated by 1) exactly reconstructing a soil solution representative of a loamy agricultural soil and, 2) constructing an ion-based experiment to determine the effects of substituting Na+ for K+ on the growth of a Valencia sweet orange nonembryogenic cell line.

Goal orientation, perceived task outcome and task demands in mathematics tasks: effects on students' attitude in actual task settings.

PubMed

Seegers, Gerard; van Putten, Cornelis M; de Brabander, Cornelis J

2002-09-01

In earlier studies, it has been found that students' domain-specific cognitions and personal learning goals (goal orientation) influence task-specific appraisals of actual learning tasks. The relations between domain-specific and task-specific variables have been specified in the model of adaptive learning. In this study, additional influences, i.e., perceived task outcome on a former occasion and variations in task demands, were investigated. The purpose of this study was to identify personality and situational variables that mediate students' attitude when confronted with a mathematics task. Students worked on a mathematics task in two subsequent sessions. Effects of perceived task outcome at the first session on students' attitude at the second session were investigated. In addition, we investigated how differences in task demands influenced students' attitude. Variations in task demands were provoked by different conditions in task-instruction. In one condition, students were told that the result on the test would add to their mark on mathematics. This outcome orienting condition was contrasted with a task-orienting condition where students were told that the results on the test would not be used to give individual grades. Participants were sixth grade students (N = 345; aged 11-12 years) from 14 primary schools. Multivariate and univariate analyses of (co)variance were applied to the data. Independent variables were goal orientation, task demands, and perceived task outcome, with task-specific variables (estimated competence for the task, task attraction, task relevance, and willingness to invest effort) as the dependent variables. The results showed that previous perceived task outcome had a substantial impact on students' attitude. Additional but smaller effects were found for variation in task demands. Furthermore, effects of previous perceived task outcome and task demands were related to goal orientation. The resulting pattern confirmed that, in general, performance-oriented learning goals emphasised the negative impact of failure experiences, whereas task-oriented learning goals had a strengthening effect on how success experiences influenced students' attitude.

GABAa excitation and synaptogenesis after Status Epilepticus - A computational study.

PubMed

França, Keite Lira de Almeida; de Almeida, Antônio-Carlos Guimarães; Saddow, Stephen E; Santos, Luiz Eduardo Canton; Scorza, Carla Alessandra; Scorza, Fulvio Alexandre; Rodrigues, Antônio Márcio

2018-03-08

The role of GABAergic neurotransmission on epileptogenesis has been the subject of speculation according to different approaches. However, it is a very complex task to specifically consider the action of the GABAa neurotransmitter, which, in its dependence on the intracellular level of Cl - , can change its effect from inhibitory to excitatory. We have developed a computational model that represents the dentate gyrus and is composed of three different populations of neurons (granule cells, interneurons and mossy cells) that are mutually interconnected. The interconnections of the neurons were based on compensation theory with Hebbian and anti-Hebbian rules. The model also incorporates non-synaptic mechanisms to control the ionic homeostasis and was able to reproduce ictal discharges. The goal of the work was to investigate the hypothesis that the observed aberrant sprouting is promoted by GABAa excitatory action. Conjointly with the abnormal sprouting of the mossy fibres, the simulations show a reduction of the mossy cells connections in the network and an increased inhibition of the interneurons as a response of the neuronal network to control the activity. This finding contributes to increasing the changes in the connectivity of the neuronal circuitry and to increasing the epileptiform activity occurrences.

Rotational diffusion of nondipolar and charged solutes in alkyl-substituted imidazolium triflimides: effect of C2 methylation on solute rotation.

PubMed

Prabhu, Sugosh R; Dutt, G B

2014-08-07

Rotational diffusion of a nondipolar solute 2,5-dimethyl-1,4-dioxo-3,6-diphenylpyrrolo[3,4-c]pyrrole (DMDPP) and a charged solute rhodamine 110 (R110) has been investigated in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM][Tf2N]) and 1-butyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide ([BMMIM][Tf2N]) to understand the influence of the C2 methylation on solute rotation. The measured reorientation times of the nondipolar solute DMDPP are similar in both the ionic liquids and follow Stokes-Einstein-Debye hydrodynamic theory with slip hydrodynamics. In contrast, rotational diffusion of the charged solute R110 in [BMIM][Tf2N] obeys stick hydrodynamics due to specific interactions with the anion of the ionic liquid. Nevertheless, the intriguing result of this study is that the reorientation times of R110 in [BMMIM][Tf2N] deviate significantly from the predictions of stick hydrodynamics, especially at ambient temperatures. The solute-solvent boundary condition parameter Cobs, which is defined as the ratio of the measured reorientation time to the one calculated using the SED theory with stick boundary condition, for R110 is lower by a factor of 2 in [BMMIM][Tf2N] compared to [BMIM][Tf2N] at 298 K. Upon increasing the temperature, Cobs gradually increases and eventually matches with that obtained in [BMIM][Tf2N] at 348 K. It has been well established that methylation of the C2 position in [BMMIM][Tf2N] switches off the main hydrogen-bonding interaction between the anion and the cation, but increases the Coulombic interactions. As a consequence of the enhanced interionic interactions between the cation and anion of the ionic liquid, specific interactions between R110 and [Tf2N] diminish leading to the faster rotation of the solute. However, such an influence is not apparent in case of DMDPP as it does not experience specific interactions with either the cation or the anion of these ionic liquids.

Quantitative Comparison of Protein Adsorption and Conformational Changes on Dielectric-Coated Nanoplasmonic Sensing Arrays.

PubMed

Ferhan, Abdul Rahim; Jackman, Joshua A; Sut, Tun Naw; Cho, Nam-Joon

2018-04-22

Nanoplasmonic sensors are a popular, surface-sensitive measurement tool to investigate biomacromolecular interactions at solid-liquid interfaces, opening the door to a wide range of applications. In addition to high surface sensitivity, nanoplasmonic sensors have versatile surface chemistry options as plasmonic metal nanoparticles can be coated with thin dielectric layers. Within this scope, nanoplasmonic sensors have demonstrated promise for tracking protein adsorption and substrate-induced conformational changes on oxide film-coated arrays, although existing studies have been limited to single substrates. Herein, we investigated human serum albumin (HSA) adsorption onto silica- and titania-coated arrays of plasmonic gold nanodisks by localized surface plasmon resonance (LSPR) measurements and established an analytical framework to compare responses across multiple substrates with different sensitivities. While similar responses were recorded on the two substrates for HSA adsorption under physiologically-relevant ionic strength conditions, distinct substrate-specific behavior was observed at lower ionic strength conditions. With decreasing ionic strength, larger measurement responses occurred for HSA adsorption onto silica surfaces, whereas HSA adsorption onto titania surfaces occurred independently of ionic strength condition. Complementary quartz crystal microbalance-dissipation (QCM-D) measurements were also performed, and the trend in adsorption behavior was similar. Of note, the magnitudes of the ionic strength-dependent LSPR and QCM-D measurement responses varied, and are discussed with respect to the measurement principle and surface sensitivity of each technique. Taken together, our findings demonstrate how the high surface sensitivity of nanoplasmonic sensors can be applied to quantitatively characterize protein adsorption across multiple surfaces, and outline broadly-applicable measurement strategies for biointerfacial science applications.

Ionic and viscoelastic mechanisms of a bucky-gel actuator

NASA Astrophysics Data System (ADS)

Kruusamäe, Karl; Sugino, Takushi; Asaka, Kinji

2015-07-01

Ionic electromechanically active polymers (IEAPs) are considered attractive candidates for soft, miniature, and lightweight actuators. The bucky-gel actuator is a carbonaceous subtype of IEAP that due to its structure (i.e. two highly porous electrodes sandwiching a thin ion-permeable electrolyte layer) and composition (i.e. being composed of soft porous polymer, carbon nanotubes, and ionic liquid) is very similar to an electric double-layer capacitor. In response to the voltage applied between the electrodes of a bucky-gel actuator, the laminar structure bends. The time domain behavior exhibits, however, a phenomenon called the back-relaxation, i.e., after some time the direction of bending is reversed even though voltage remains constant. In spite of the working mechanism of IEAP actuators being generally attributed to the transport of ions within the soft multilayer system, the specific details remain unclear. A so-called two-carrier model proposes that the bending and subsequent back-relaxation are caused by the relocation of two ionic species having different mobilities as they enter and exit the electrode layers. By adopting the two-carrier model for bucky-gel actuators, we see very good agreement between the mathematical representation and the experimental data of the electromechanical behavior. Furthermore, since the bucky-gel actuator is viscoelastic, we propose to use the time domain response of a blocking force as the key parameter related to the inner ionic mechanism. We also introduce a method to estimate the viscoelastic creep compliance function from the time domain responses for curvature and blocking force. This analysis includes four types of bucky-gel actuators of varying composition and structure.

Composite fabrication and polymer modification using neoteric solvents

NASA Astrophysics Data System (ADS)

Eastman, Scott A.

This thesis is divided into two research initiatives: The fabrication and study of bulk, co-continuous, cellulosic-polymer composites with the aid of supercritical CO2 (SC CO2); and the study of poly(vinyl alcohol) (PVOH) modification and surface activity in ionic liquids. The first part of this thesis utilizes the tunable solubility, gas-like diffusivity, and omniphilic wettability of SC CO2 to incorporate and subsequently polymerize silicone and poly(enemer) prepolymer mixtures throughout various cellulosic substrates. Chapters two and three investigate the mechanical properties of these composites and demonstrate that nearly every resulting composite demonstrates an improved flexural modulus and energy release rate upon splitting. Fire resistance of these composites was also investigated and indicates that the heat release rate, total heat released, and char yield were significantly improved upon for all silicone composites compared to the untreated cellulosic material. Chapter four looks specifically at aspen-silicone composites for thermo-oxidative studies under applied loads in order to study the effect of silicone incorporation on the failure kinetics of aspen. The aspen-silicone composites tested under these conditions demonstrated significantly longer lifetimes under the same loading and heating conditions compared with untreated aspen. The second part of this thesis focuses on studying ionic liquids as potentially useful solvents and reaction media for poly(vinyl alcohol). Two ionic liquids (1-Butyl-3-methylimidizolium chloride and tributylethylphosphonium diethylphosphate) were found to readily dissolve PVOH. More importantly, we have demonstrated that these solvents can be used as inert reaction media for PVOH modification. Both ionic liquids were found to facilitate the quantitative esterification of PVOH, while only the phosphonium ionic liquid supports the quantitative urethanation of the polymer. In an attempt to tune the surface properties of ionic liquid/polymer solutions, PVOH was also partially esterified with low surface energy substituents. Both surface tension and surface composition of the ionic liquid/polymer solutions can be manipulated by the stoichiometric addition of low surface energy acid chlorides. This work on the modification of PVOH can be directly applied to the modification of polysaccharides such as cellulose which could have important implications from a sustainability and energy standpoint.

Estimating Concentrations of Road-Salt Constituents in Highway-Runoff from Measurements of Specific Conductance

USGS Publications Warehouse

Granato, Gregory E.; Smith, Kirk P.

1999-01-01

Discrete or composite samples of highway runoff may not adequately represent in-storm water-quality fluctuations because continuous records of water stage, specific conductance, pH, and temperature of the runoff indicate that these properties fluctuate substantially during a storm. Continuous records of water-quality properties can be used to maximize the information obtained about the stormwater runoff system being studied and can provide the context needed to interpret analyses of water samples. Concentrations of the road-salt constituents calcium, sodium, and chloride in highway runoff were estimated from theoretical and empirical relations between specific conductance and the concentrations of these ions. These relations were examined using the analysis of 233 highwayrunoff samples collected from August 1988 through March 1995 at four highway-drainage monitoring stations along State Route 25 in southeastern Massachusetts. Theoretically, the specific conductance of a water sample is the sum of the individual conductances attributed to each ionic species in solution-the product of the concentrations of each ion in milliequivalents per liter (meq/L) multiplied by the equivalent ionic conductance at infinite dilution-thereby establishing the principle of superposition. Superposition provides an estimate of actual specific conductance that is within measurement error throughout the conductance range of many natural waters, with errors of less than ?5 percent below 1,000 microsiemens per centimeter (?S/cm) and ?10 percent between 1,000 and 4,000 ?S/cm if all major ionic constituents are accounted for. A semi-empirical method (adjusted superposition) was used to adjust for concentration effects-superposition-method prediction errors at high and low concentrations-and to relate measured specific conductance to that calculated using superposition. The adjusted superposition method, which was developed to interpret the State Route 25 highway-runoff records, accounts for contributions of constituents other than calcium, sodium, and chloride in dilute waters. The adjusted superposition method also accounts for the attenuation of each constituent's contribution to conductance as ionic strength increases. Use of the adjusted superposition method generally reduced predictive error to within measurement error throughout the range of specific conductance (from 37 to 51,500 ?S/cm) in the highway runoff samples. The effects of pH, temperature, and organic constituents on the relation between concentrations of dissolved constituents and measured specific conductance were examined but these properties did not substantially affect interpretation of the Route 25 data set. Predictive abilities of the adjusted superposition method were similar to results obtained by standard regression techniques, but the adjusted superposition method has several advantages. Adjusted superposition can be applied using available published data about the constituents in precipitation, highway runoff, and the deicing chemicals applied to a highway. This semi-empirical method can be used as a predictive and diagnostic tool before a substantial number of samples are collected, but the power of the regression method is based upon a large number of water-quality analyses that may be affected by a bias in the data.

Entropic and Electrostatic Effects on the Folding Free Energy of a Surface-Attached Biomolecule: An Experimental and Theoretical Study

PubMed Central

Watkins, Herschel M.; Vallée-Bélisle, Alexis; Ricci, Francesco; Makarov, Dmitrii E.; Plaxco, Kevin W.

2012-01-01

Surface-tethered biomolecules play key roles in many biological processes and biotechnologies. However, while the physical consequences of such surface attachment have seen significant theoretical study, to date this issue has seen relatively little experimental investigation. In response we present here a quantitative experimental and theoretical study of the extent to which attachment to a charged –but otherwise apparently inert– surface alters the folding free energy of a simple biomolecule. Specifically, we have measured the folding free energy of a DNA stem loop both in solution and when site-specifically attached to a negatively charged, hydroxyl-alkane-coated gold surface. We find that, whereas surface attachment is destabilizing at low ionic strength it becomes stabilizing at ionic strengths above ~130 mM. This behavior presumably reflects two competing mechanisms: excluded volume effects, which stabilize the folded conformation by reducing the entropy of the unfolded state, and electrostatics, which, at lower ionic strengths, destabilizes the more compact folded state via repulsion from the negatively charged surface. To test this hypothesis we have employed existing theories of the electrostatics of surface-bound polyelectrolytes and the entropy of surface-bound polymers to model both effects. Despite lacking any fitted parameters, these theoretical models quantitatively fit our experimental results, suggesting that, for this system, current knowledge of both surface electrostatics and excluded volume effects is reasonably complete and accurate. PMID:22239220

Electroviscous Effects in Ceramic Nanofiltration Membranes.

PubMed

Farsi, Ali; Boffa, Vittorio; Christensen, Morten Lykkegaard

2015-11-16

Membrane permeability and salt rejection of a γ-alumina nanofiltration membrane were studied and modeled for different salt solutions. Salt rejection was predicted by using the Donnan-steric pore model, in which the extended Nernst-Planck equation was applied to predict ion transport through the pores. The solvent flux was modeled by using the Hagen-Poiseuille equation by introducing electroviscosity instead of bulk viscosity. γ-Alumina particles were used for ζ-potential measurements. The ζ-potential measurements show that monovalent ions did not adsorb on the γ-alumina surface, whereas divalent ions were highly adsorbed. Thus, for divalent ions, the model was modified, owing to pore shrinkage caused by ion adsorption. The ζ-potential lowered the membrane permeability, especially for membranes with a pore radius lower than 3 nm, a ζ-potential higher than 20 mV, and an ionic strength lower than 0.01 m. The rejection model showed that, for a pore radius lower than 3 nm and for solutions with ionic strengths lower than 0.01 m, there is an optimum ζ-potential for rejection, because of the concurrent effects of electromigration and convection. Hence, the model can be used as a prediction tool to optimize membrane perm-selectivity by designing a specific pore size and surface charge for application at specific ionic strengths and pH levels. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Solubility and modeling acid-base properties of adrenaline in NaCl aqueous solutions at different ionic strengths and temperatures.

PubMed

Bretti, Clemente; Cigala, Rosalia Maria; Crea, Francesco; De Stefano, Concetta; Vianelli, Giuseppina

2015-10-12

Solubility and acid-base properties of adrenaline were studied in NaCl aqueous solutions at different ionic strengths (0