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Ionic contrast

Esa-Ville Immonen, Andrew S French, Päivi H Torkkeli, Hongxia Liu, Mikko Vähäsöyrinki, Roman V Frolov
The principles underlying evolutionary selection of ion channels for expression in sensory neurons are unclear. Among species possessing microvillar photoreceptors the major ionic conductances have only been identified in Drosophila melanogaster. In Drosophila depolarization is provided by light-activated TRP channels with a minor contribution from TRPL channels, while repolarization is mediated by sustained voltage-gated K(+) (Kv) channels of the Shab family. Bright light stimulates Shab channels, further restricting depolarization and improving membrane bandwidth...
January 13, 2017: Journal of Physiology
Ying Li, Gang Liu, Xin Lou, Zhiye Chen, Lin Ma
This experiment aimed to compare the ionic (Gadodiamide, Gd-DTPA-BMA) and non-ionic (Gadopentetate dimeglumine, Gd-DTPA) gadolinium-based contrast agents (GBCA) in the quantitative evaluation of C6 glioma with dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). A C6 glioma model was established in 12 Wistar rats, and magnetic resonance (MR) scans were performed six days after tumor implantation. Imaging was performed using a 3.0-T MR scanner with a 7-inch handmade circular coil. Pre-contrast T1 mapping and dynamic contrast-enhanced T1WI after a bolus injection (0...
January 4, 2017: Science China. Life Sciences
Lye Lin Lock, Yuguo Li, Xinpei Mao, Hanwei Chen, Verena Staedtke, Renyuan Bai, Wang Ma, Ran Lin, Yi Li, Guanshu Liu, Honggang Cui
Gadolinium (Gd)-based compounds and materials are the most commonly used magnetic resonance imaging (MRI) contrast agents in the clinic; however, safety concerns associated with their toxicities in the free ionic form have promoted the development of new generations of metal-free contrast agents. Here we report a supramolecular strategy to convert an FDA-approved anticancer drug, Pemetrexed (Pem), to a molecular hydrogelator with inherent chemical exchange saturation transfer (CEST) MRI signals. The rationally designed drug-peptide conjugate can spontaneously associate into filamentous assemblies under physiological conditions and consequently form theranostic supramolecular hydrogels for injectable delivery...
January 11, 2017: ACS Nano
David V McCalley
Trifluoracetic acid (TFA) added to the aqueous acetonitrile mobile phase induces some unexpected changes in the ionic component of retention in hydrophilic interaction separations when using Type B silica and amide-bonded silica columns. TFA use results in anion exchange properties which contrast with the cation exchange typically found with ammonium salt buffers. The significant cation exchange properties of silica hydride columns are also moderated by TFA. Similar behaviour was shown in a metal- free amide column operated on a system washed with a metal complexing agent, suggesting that adsorbed metal cations were not responsible for this anion exchange behaviour...
December 15, 2016: Journal of Chromatography. A
Dawoud Al Mahrouqi, Jan Vinogradov, Matthew D Jackson
Despite the broad range of interest and applications, controls on calcite surface charge in aqueous solution, especially at conditions relevant to natural systems, remain poorly understood. The primary data source to understand calcite surface charge comprises measurements of zeta potential. Here we collate and review previous measurements of zeta potential on natural and artificial calcite and carbonate as a resource for future studies, compare and contrast the results of these studies to determine key controls on zeta potential and where uncertainties remain, and report new measurements of zeta potential relevant to natural subsurface systems...
December 26, 2016: Advances in Colloid and Interface Science
Dongmei Yan, Zhihong Zhang, Qingming Luo, Xiaoquan Yang
With the development of hybrid imaging scanners, micro-CT is widely used in locating abnormalities, studying drug metabolism, and providing structural priors to aid image reconstruction in functional imaging. Due to the low contrast of soft tissues, segmentation of soft tissue organs from mouse micro-CT images is a challenging problem. In this paper, we propose a mouse segmentation scheme based on dynamic contrast enhanced micro-CT images. With a homemade fast scanning micro-CT scanner, dynamic contrast enhanced images were acquired before and after injection of non-ionic iodinated contrast agents (iohexol)...
2017: PloS One
Chunrui Ma, Rongtao Lu, Guangliang Hu, Jinsheng Han, Ming Liu, Jun Li, Judy Z Wu
Graphene were inserted the interface between electric dipole layers from the DEME-TFSI ionic liquid (top gate) and ferroelectric Pb0.92La0.08Zr0.52Ti0.48O3 (PLZT, back-gate) to probe the interface dipole-dipole interaction in response to DC and pulsed gate voltages. A highly complicated behavior of the interface dipole-dipole interaction has been revealed as a combination of electrostatic and electrochemical effects. The interfacial polar molecules in the DEME-TFSI electrical double layer are pinned with assistance of the PLZT back-gate in response to a DC top-gate pump, leading to strong nonlinear electrochemical behavior...
January 6, 2017: ACS Applied Materials & Interfaces
Benedict C Oyiga, Ram C Sharma, Michael Baum, Francis C Ogbonnaya, Jens Léon, Agim Ballvora
The increasing salinization of agricultural lands is a threat to global wheat production. Understanding of the mechanistic basis of salt tolerance (ST) is essential for developing breeding and selection strategies that would allow for increased wheat production under saline conditions to meet the increasing global demand. We used a set of 150 diversity panel genotyped with 90 K SNP Chip and phenotyped for ST across three growth stages and for ionic (leaf K(+) and Na(+) contents) traits to dissect the genetic architecture regulating ST in wheat...
January 3, 2017: Plant, Cell & Environment
A R Alfonso-Avila, É Charbonneau, P Y Chouinard, G F Tremblay, R Gervais
Previous studies reported that addition of K2CO3 to high-concentrate diets improved milk fat synthesis, although the mechanism is yet to be established. The objective of the current experiment was to investigate the effects of dietary cation-anion difference (DCAD), cation source, and buffering ability of the mineral supplement on rumen biohydrogenation of fatty acids and production performance in dairy cows fed a high-concentrate diet. Thirty-five early-lactation Holstein cows (25 multiparous ruminally fistulated and 10 primiparous nonfistulated) were used in a randomized complete block design (7 blocks) with 33-d periods, including a 5-d pre-treatment collection period used as a covariate...
December 29, 2016: Journal of Dairy Science
G Rigaux, C V Gheran, M Callewaert, C Cadiou, S N Voicu, A Dinischiotu, M C Andry, L Vander Elst, S Laurent, R N Muller, A Berquand, M Molinari, S Huclier-Markai, F Chuburu
Chitosan CS-tripolyphosphate TPP/hyaluronic acid HA nanohydrogels loaded with gadolinium chelates (GdDOTA ⊂ CS-TPP/HA NGs) synthesized by ionic gelation were designed for lymph node (LN) MRI. In order to be efficiently drained to LNs, nanogels (NGs) needed to exhibit a diameter ϕ < 100 nm. For that, formulation parameters were tuned, using (i) CS of two different molecular weights (51 and 37 kDa) and (ii) variable CS/TPP ratio (2 < CS/TPP < 8). Characterization of NG size distribution by dynamic light scattering (DLS) and asymetrical flow-field-flow-fractionation (AF4) showed discrepancies since DLS diameters were consistently above 200 nm while AF4 showed individual nano-objects with ϕ < 100 nm...
February 3, 2017: Nanotechnology
Milad Rabbani Esfahani, Vasanta L Pallem, Holly A Stretz, Martha J M Wells
The interaction of macromolecules with gold nanoparticles (GNPs) is of interest in the emerging field of biomedical and environmental detection devices. However, the physicochemical properties, including spectra, of GNPs in aqueous solution in the absence of metal-macromolecular interactions must first be considered before their activity in biological and environmental systems can be understood. The specific objective of this research was to experimentally illuminate the role of nanoparticle core size on the spectral (simultaneous consideration of extinction, emission, and scattering) versus aggregation behaviors of citrate-coated GNPs (CT-GNPs)...
December 5, 2016: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Bing Bu, Zhiqi Tian, Dechang Li, Baohua Ji
Membrane fusion lies at the heart of neuronal communication but the detailed mechanism of a critical step, fusion pore initiation, remains poorly understood. Here, through atomistic molecular dynamics simulations, a transient pore formation induced by a close contact of two apposed bilayers is firstly reported. Such a close contact gives rise to a high local transmembrane voltage that induces the transient pore formation. Through simulations on two apposed bilayers fixed at a series of given distances, the process in which two bilayers approaching to each other under the pulling force from fusion proteins for membrane fusion was mimicked...
2016: Frontiers in Molecular Neuroscience
Hongduo Lu, Bin Li, Sture Nordholm, Clifford E Woodward, Jan Forsman
An asymmetric restricted primitive model (ARPM) of electrolytes is proposed as a simple three parameter (charge q, diameter d, and charge displacement b) model of ionic liquids and solutions. Charge displacement allows electrostatic and steric interactions to operate between different centres, so that orientational correlations arise in ion-ion interactions. In this way the ionic system may have partly the character of a simple ionic fluid/solid and of a polar fluid formed from ion pairs. The present exploration of the system focuses on the ion pair formation mechanism, the relative concentration of paired and free ions and the consequences for the cohesive energy, and the tendency to form fluid or solid phase...
December 21, 2016: Journal of Chemical Physics
Stefanie Dehnen, Silke Santner, Jan J Weigand, Sivathmeehan Yogendra
The synthesis of anionic chalcogenidometalate superspheres can be achieved from [Ge4Se10]4- salts and SnCl4 in ionic liquids with (Cn(C1)C1Im)+ cations (n = 4, 6, 8). Its formation is apparently independent from the lengths of the Cn chain and the presence or absence of a second methyl group at the ionic liquid cation that are exchanged for alkali metal cations during the reactions, although this may appear counterintuitive. In contrast, and equally counterintuitive, the ionic liquid anion was found to play a crucial role for both the general observability as well as the crystal yield and quality of the products, although they are not part of the product: a minimum content of chloride is needed, while ionic liquids with [BF4]- anions alone do not support the product formation/crystallization...
December 23, 2016: Chemistry: a European Journal
Jeevapani J Hettige, Weththasinghage D Amith, Edward W Castner, Claudio J Margulis
The behavior in the bulk and at interfaces of biphilic ionic liquids in which either the cation or anion possesses moderately long alkyl tails is to a significant degree well understood. Less clear is what happens when both the cation and anion possess tails that are not apolar, such as in the case of ether functionalities. The current article discusses the structural characteristics of C2OC2OC2-mim(+)/C2OC2OC2-OSO3(-) in the bulk and at the vacuum interface. We find that the vacuum interface affects only the nanometer length scale...
December 22, 2016: Journal of Physical Chemistry. B
Qianqian Cao, Lujuan Li, Fengli Huang, Chuncheng Zuo
We report an all-atom molecular dynamics study of the structures and dynamics of salty water droplets on a silicon surface under the influence of applied electric field. Our simulation results support ion-specific effects on the elongation dynamics of salty nanodroplets, induced by the field. This feature has not been explored up to now in monovalent salts. Nevertheless, the importance of ion-specific effects is widely confirmed in biological and colloidal systems. In particular, the increase of salt concentration enhances the effect of the nature of ions on the wetting properties of droplets...
December 29, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Paulo Schmitz, Rene Jakelski, Marcelina Pyschik, Kirsi Jalkanen, Sascha Nowak, Martin Winter, Peter Maria Bieker
Ionic liquids (ILs) are considered as suitable electrolyte components for lithium metal batteries. Imidazolium cation-based ILs were previously found as applicable for battery systems with a lithium metal negative electrode. However, in this work we show that in contrast to the well-known IL N-butyl-N-methylpyrrolidinium bis((trifluoromethyl)sulfonyl)imide (Pyr14TFSI), 1-ethyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)imide [C2MIm]TFSI and 1-butyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)imide ([C4MIm]TFSI) are chemically not stable versus metallic lithium...
December 20, 2016: ChemSusChem
Silvia Caioli, Cinzia Severini, Teresa Ciotti, Fulvio Florenzano, Domenico Pimpinella, Pamela Petrocchi Passeri, Gianfranco Balboni, Patrizio Polisca, Roberta Lattanzi, Robert Nisticò, Lucia Negri, Cristina Zona
The accumulation of β-amyloid (Aβ) is one of the hallmarks of Alzheimer disease (AD). Beyond the inflammatory reactions promoted by Aβ, it has been demonstrated that the prokineticin (PK) system, composed of the chemokine prokineticin 2 (PK2) and its receptors, is involved in Aβ toxicity. In this study we have analyzed how the Aβ chronic treatment affects the glutamatergic transmission on neurons from primary cortical cultures, clearly demonstrating the PK system involvement on its action mechanism. In fact, we have observed a significant increase of the ionic current through the AMPA receptors in primary cortical neurons and an up-regulation of the PK system in cultures chronically treated with Aβ...
December 15, 2016: Neuropharmacology
William Shotyk, Beatriz Bicalho, Chad W Cuss, Mark W Donner, Iain Grant-Weaver, Sandor Haas-Neill, Muhammad B Javed, Michael Krachler, Tommy Noernberg, Rick Pelletier, Claudio Zaccone
Water samples were collected on the Athabasca River (AR), upstream and downstream from bitumen mines and upgrading facilities, to identify changes in water quality due to industrial activities in this region of northern Alberta, Canada. Starting upstream of Fort McMurray and proceeding downstream ca. 100km, waters were collected in duplicate at 13 locations on the main stem of the river, as well as 5 tributary streams, using ultraclean sampling protocols developed for polar snow and ice. To estimate potential bioaccessibility, trace elements of concern (Ag, Cd, Pb, Sb, Tl) were determined in the dissolved fraction (<0...
December 16, 2016: Science of the Total Environment
Elena N Makarova, Evgeny G Shakhmatov, Vladimir A Belyy
Annual dynamics of accumulation and changes in the monosaccharide composition of pectin-, arabinan- and galactan-containing polysaccharides and binding glycans isolated from greenery (thin branches with needles) of Norway spruce were investigated in this study. The polysaccharides were compared with polysaccharides of Siberian fir according to the yields, composition and content of typical components. It was shown that Norway spruce greenery contains lowly methyl-esterified pectin extracted with ammonium oxalate, which is a part of protopectic complex and is bound with components of cell walls via ionic bonds...
February 10, 2017: Carbohydrate Polymers
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