Association and liquid structure of pyridine-acetic acid mixtures determined from neutron scattering using a ‘free proton’ EPSR simulation model

The liquid structure of pyridine-acetic acid mixtures have been investigated using neutron scattering at various mole fractions of acetic acid, χHOAc = 0.33, 0.50, and 0.67, and compared to the structures of neat pyridine and acetic acid. Data has been modelled using Empirical Potential Structure Refinement (EPSR) with a ‘free proton’ reference model, which has no prejudicial weighting towards either the existence of molecular or ionised species. Analysis of the neutron scattering results shows the existence of hydrogen-bonded acetic acid chains with pyridine inclusions, rather than the formation of an ionic liquid by proton transfer.

Measurement of proton-driven antiport in Escherichia coli

Secondary active transport of substrates across the inner membrane is vital to the bacterial cell. Of the secondary active transporter families, the ubiquitous major facilitator superfamily (MFS) is the largest and most functionally diverse (Reddy et al., 2012). Recently, it was reported that the MFS multidrug efflux protein MdtM from Escherichia coli (E. coli) functions physiologically in protection of bacterial cells against bile salts (Paul et al., 2014). The MdtM transporter imparts bile salt resistance to the bacterial cell by coupling the exchange of external protons (H+) to the efflux of bile salts from the cell interior via an antiport reaction. This protocol describes, using fluorometry, how to detect the bile salt/H+ antiport activity of MdtM in inverted membrane vesicles of an antiporter-deficient strain of E. coli TO114 cells by measuring transmembrane ∆pH. This method exploits the changes that occur in the intensity of the fluorescence signal (quenching and dequenching) of the pH-sensitive dye acridine orange in response to changes in [H+] in the vesicular lumen. Due to low levels of endogenous transporter expression that would normally make the contribution of individual transporters such as MdtM to proton-driven antiport difficult to detect, the method typically necessitates that the transporter of interest be overexpressed from a multicopy plasmid. Although the first section of the protocol described here is very specific to the overexpression of MdtM from the pBAD/Myc-His A expression vector, the protocol describing the subsequent measurement of bile salt efflux by MdtM can be readily adapted for measurement of antiport of other substrates by any other antiporter that exchanges protons for countersubstrate.

Azepanium-based ionic liquids as green electrolytes for high voltage supercapacitors

This work provides a first-time-study of Azepanium-based ionic liquids (ILs) as electrolyte components for electrochemical double layer capacitors (EDLCs). Herein, two Azepanium-based ILs, namely N-methyl, N-butyl-azepanium bis(trifluoromethanesulfonyl)imide (Azp(14)TFSI) and N-methyl, N-hexyl-azepanium bis(trifluoromethanesulfonyl)imide (Azp(16)TFSI) were compared with the established IL N-butyl, N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr(14)TFSI) in terms of viscosity, conductivity, thermal stability and electrochemical behavior in EDLC systems. The ILs' operative potentials were found to be comparable, leading to operative voltages up to 3.5 V without significant electrolyte degradation. 

On the Performances of Ionic Liquid-Based Electrolytes for Li-NMC Batteries

Herein, the N-butyl-N-methylpyrrolidinium bis(fluorosulfonyl)amide and the N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl)amide room temperature ionic liquids, combined with the lithium bis(trifluoromethanesulfonyl)amide salt, are investigated as electrolytes for Li/LiNi1/3Mn1/3Co1/3O2 (Li/NMC) batteries. To conduct this study, volumetric properties, ionic conductivity and viscosity of the pure ionic liquids and selected electrolytes were firstly determined as a function of temperature and composition in solution. These data were then compared with those measured in the case of the standard alkyl carbonate-based electrolyte: e.g. the EC/PC/3DMC + 1 mol·L−1 LiPF6. The compatibility of the selected electrolytes with the lithium electrode was then investigated by following the evolution of Li/electrolyte interfaces through impedance measurements. Interestingly, the impedances of the investigated Li/electrolyte interfaces were found to be more than three times lower than that measured using the standard electrolyte. Finally, electrochemical performances of the ionic liquid-based electrolytes were investigated using galvanostatic charge and discharge and cyclic voltammetry of each Li/NMC cell. Using these electrolytes, each tested Li cell reaches up to 145 mA·h·g−1 at C/10 and 110 mA·h·g−1 at C with a coulombic efficiency close to 100 %.

Mixtures of azepanium based ionic liquids and propylene carbonate as high voltage electrolytes for supercapacitors

This work provides a study of mixtures of the azepanium-based ionic liquid (IL) N-methyl, N-butyl-azepanium bis[(trifluoromethane) sulfonyl]imide (Azp₁₄TFSI) and propylene carbonate (PC) as electrolyte components in electrochemical double layer capacitors (EDLCs). The considered mixtures' properties were then compared to the properties of mixtures of N-butyl, N-methylpyrrolidinium bis[(trifluoromethane) sulfonyl]imide (Pyr₁₄TFSI) and PC in terms of viscosity, conductivity and electrochemical behavior. The mixtures' operative potentials were found to be comparable to each other, leading to operative voltages as high as 3.5 V, while retaining the low viscosities and high conductivities of PC based EDLC electrolytes.

Beam profiles of proton and carbon ions in the relativistic transparency regime

Ion acceleration from relativistic laser solid interactions has been of particular interest over the last decade. While beam profiles have been studied for target normal sheath acceleration (TNSA), such profiles have yet to be described for other mechanisms. Here, experimental data is presented, investigating ion beam profiles from acceleration governed by relativistic transparent laser plasma interaction. The beam shape of carbon C6+ ions and protons has been measured simultaneously with a wide angle spectrometer. It was found that ion beams deviate from the typical Gaussian-like shape found with TNSA and that the profile is governed by electron dynamics in the volumetric laser-plasma interaction with a relativistically transparent plasma; due to the ponderomotive force electrons are depleted from the center of the laser axis and form lobes affecting the ion beam structure. The results are in good agreement with high resolution three-dimensional-VPIC simulations and can be used as a new tool to experimentally distinguish between different acceleration mechanisms.

Transport of laser accelerated proton beams and isochoric heating of matter

The acceleration of intense proton and ion beams by ultra-intense lasers has matured to a point where applications in basic research and technology are being developed. Crucial for harvesting the unmatched beam parameters driven by the relativistic electron sheath is the precise control of the beam. We report on recent experiments using the PHELIX laser at GSI, the VULCAN laser at RAL and the TRIDENT laser at LANL to control and use laser accelerated proton beams for applications in high energy density research. We demonstrate efficient collimation of the proton beam using high field pulsed solenoid magnets, a prerequisite to capture and transport the beam for applications. Furthermore we report on two campaigns to use intense, short proton bunches to isochorically heat solid targets up to the warm dense matter state. The temporal profile of the proton beam allows for rapid heating of the target, much faster than the hydrodynamic response time thereby creating a strongly coupled plasma at solid density. The target parameters are then probed by X-ray Thomson scattering (XRTS) to reveal the density and temperature of the heated volume. This combination of two powerful techniques developed during the past few years allows for the generation and investigation of macroscopic samples of matter in states present in giant planets or the interior of the earth.

Determination of 3,4-methylenedioxyamphetamine analogues (''ecstasy'') by proton nuclear magnetic resonance spectrometry

A procedure for the determination of three commonly encountered ecstasy type drugs has been demonstrated using proton nuclear magnetic resonance spectrometry (H-1-NMR).

Proton irradiation of DNA nucleosides in the gas phase

The four DNA nucleosides guanosine, adenosine, cytidine and thymidine have been produced in the gas phase by a laser thermal desorption source, and irradiated by a beam of protons with 5 keV kinetic energy. The molecular ions as well as energetic neutrals formed have been analyzed by mass spectrometry in order to shed light on the ionization and fragmentation processes triggered by proton collision. A range of 8-20 eV has been estimated for the binding energy of the electron captured by the proton. Glycosidic bond cleavage between the base and sugar has been observed with a high probability for all nucleosides, resulting in predominantly intact base ions for guanosine, adenosine, and cytidine but not for thymidine where intact sugar ions are dominant. This behavior is influenced by the ionization energies of the nucleobases (G < A < C < T), which seems to determine the localization of the charge following the initial ionization. This charge transfer process can also be inferred from the production of protonated base ions, which have a similar dependence on the base ionization potential. Other dissociation pathways have also been identified, including further fragmentation of the base and sugar moieties for thymidine and guanosine, respectively, and partial breakup of the sugar ring without glycosidic bond cleavage mainly for adenosine and cytidine. These results show that charge localization following ionization by proton irradiation is important in determining dissociation pathways of isolated nucleosides, which could in turn influence direct radiation damage in DNA.

Development and evaluation of a novel integrated anti-icing/de-icing technology for carbon fibre composite aerostructures using an electro-conductive textile

The preliminary evaluation is described of a new electro-thermal anti-icing/de-icing device for carbon fibre composite aerostructures. The heating element is an electro-conductive carbon-based textile (ECT) by Gorix. Electrical shorting between the structural carbon fibres and the ECT was mitigated by incorporating an insulating layer formed of glass fibre plies or a polymer film. A laboratory-based anti-icing and de-icing test program demonstrated that the film-insulated devices yielded better performance than the glssass fibre insulated ones. The heating capability after impact damage was maintained as long as the ECT fabric was not breached to the extent of causing electrical shorting. A modified structural scarf repair was shown to restore the heating capacity of a damaged specimen.

High-energy monoenergetic proton beams from two stage acceleration with a slow laser pulse

We present a new regime to generate high-energy quasimonoenergetic proton beams in a "slow-pulse" regime, where the laser group velocity vg<c is reduced by an extended near-critical density plasma. In this regime, for properly matched laser intensity and group velocity, ions initially accelerated by the light sail (LS) mode can be further trapped and reflected by the snowplough potential generated by the laser in the near-critical density plasma. These two acceleration stages are connected by the onset of Rayleigh-Taylor-like (RT) instability. The usual ion energy spectrum broadening by RT instability is controlled and high quality proton beams can be generated. It is shown by multidimensional particle-in-cell simulation that quasimonoenergetic proton beams with energy up to hundreds of MeV can be generated at laser intensities of 1021W/cm².