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# Ionic contrast

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#1
Arun Kumar Sagotra, Claudio Cazorla
Finding solid-state electrolytes with high ionic conductivity near room temperature is an important prerequisite for developing all-solid-state electrochemical batteries. Here, we investigate the effects of point defects (vacancies) and biaxial stress on the superionic properties of fast-ion conductors (represented by the archetypal compounds CaF$_{2}$, Li-rich anti-perovskite Li$_{3}$OCl, and AgI) by using classical molecular dynamics and first-principles simulation methods. We find that the critical superionic temperature of all analysed families of fast-ion conductors can be reduced by several hundreds of degrees through the application of relatively small biaxial stresses ($|\sigma| \le 1$~GPa) on slightly defective samples ($c_{v} \sim 1$\%)...
October 16, 2017: ACS Applied Materials & Interfaces
#2
Ankur A Awasthi, Prabhat K Singh
Proton transfer reactions on biosurfaces play an important role in a myriad of biological processes. Herein, Excited-state proton transfer (ESPT) reaction of 8-Hydroxypyranine-1, 3, 6-trisulfonate (HPTS) has been investigated in the presence of an important therapeutic protein, Protamine, using ground-state absorption, steady-state and detailed time-resolved emission measurements. HPTS forms a 1:1 complex with PrS with high association constant of 2.6 x 104 M-1. The binding of HPTS with Protamine leads to a significant modulation in the ground state prototropic equilibrium causing a downward shift of 1...
October 15, 2017: Journal of Physical Chemistry. B
#3
Katharina Häckl, Andrea Mühlbauer, Jesús F Ontiveros, Sinisa Marinkovic, Boris Estrine, Werner Kunz, Véronique Nardello-Rataj
HYPOTHESIS: In contrast to anionic and nonionic amphiphilic substances, bio-based cationic ones are very rare. Cationic amphiphiles are mostly based on quaternary ammonium, pyridinium or imidazolium groups that are either badly biodegradable or have toxic residues even after degradation. In the search for green alternatives to cationic hydrotropes and amphiphiles, natural l-carnitine could be a promising candidate for a cationic headgroup. EXPERIMENTS: By esterification of carnitine in one step and with low cost, cationic molecules with alkyl chain length of n=2-14 could be obtained...
September 28, 2017: Journal of Colloid and Interface Science
#4
Ryo Shimada, Jiro Ezaki, Kazuhiko Kibayashi
An ionically hypertonic contrast medium Urografin® was inadvertently administered into the subarachnoid space of an individual and this resulted in convulsions and acute respiratory failure. We examined the effects of subarachnoid Urografin® injections on the rat central nervous system. The onset and frequency of the convulsions, as well as fatality, were dependent on the amount of Urografin® administered. No convulsions were observed in rats receiving injections of hypertonic NaCl solution or saline. The results confirmed that subarachnoid injections of Urografin® cause convulsions and death, as previously reported in human cases, and our study ascertained the causal relationship between the above malpractice and fatal outcomes...
September 30, 2017: Legal Medicine
#5
John P Stegemeier, Astrid Avellan, Gregory V Lowry
Ag0 and CuO engineered nanomaterials (ENMs), or their sulfidized forms are introduced into freshwater wetlands through wastewater effluent and agricultural runoff. Knowledge about the rates of transformations of these ENMs in realistic environments, and the impact of the form of the incoming ENM (i.e. sulfidized or pristine) on bioavailability and fate is limited. Here, five freshwater wetland mesocosms were exposed to 3g of total metal as CuO, CuS, Ag0 or Ag2S ENMs, or soluble CuNO3, added weekly for one month...
October 10, 2017: Environmental Science & Technology
#6
Tao Zhang, Thomas Doert, Michael Ruck
Homogeneous powders of almost spherical particles of SrTiO3 with diameters of about 1 μm and large surface areas of up to 186 m(2) g(-1) were obtained from a facile one-pot solvothermal synthesis. Thorough characterization by X-ray diffraction (XRD), scanning electron microscopy (SEM), (high-resolution) transmission electron microscopy, and nitrogen physisorption measurements revealed the hierarchical architecture of the particles down to the scale of a few nanometers. In contrast to SrTiO3 samples obtained by high-temperature solid-state reaction, the particles are neither agglomerated nor sintered above the micrometer scale...
October 9, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
#7
Toshihiko Oka, Moynul Hasan, Md Zahidul Islam, Md Moniruzzaman, Masahito Yamazaki
Electrostatic interactions (EIs) play important roles in the structure and stability of inverse bicontinuous cubic (QII) phases of lipid membranes. We examined the effect of pH on the phase of dioleoylphosphatidylserine (DOPS)/monoolein (MO) membranes at low ionic strengths using small-angle X-ray scattering (SAXS). We found that the phase transitions from lamellar liquid-crystalline (Lα) to primitive cubic (QII(P)) phases in DOPS/MO (2/8 molar ratio) membranes occurred in buffers containing 50 mM NaCl at and below the final pH of 2...
October 13, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
#8
REVIEW
Maria Vittoria Spampinato, Ahad Abid, Maria Gisele Matheus
Millions of radiologic examinations requiring the use of iodinated contrast are performed yearly in North America. Triiodobenzoic acid, the contrast agent molecule currently in use, is a benzene ring covalently bonded to the 3 iodine atoms. Iodinated contrast media can be divided in 4 categories: ionic monomers, ionic dimers, nonionic monomer, and nonionic dimers. Currently, second- and third-generation nonionic low-osmolar and iso-osmolar contrast media are used in clinical practice. The search for a safer and more effective iodinated contrast agents remains an ongoing challenge and important research topic...
November 2017: Magnetic Resonance Imaging Clinics of North America
#9
Puja Banerjee, Biman Bagchi
In contrast to simple monatomic alkali and halide ions, complex polyatomic ions such as nitrate, acetate, nitrite, and chlorate have not been studied in any great detail. Experiments have shown that diffusion of polyatomic ions exhibits many remarkable anomalies; notable among them is the fact that polyatomic ions with similar size show large difference in their diffusivity values. This fact has drawn relatively little interest in scientific discussions. We show here that a mode-coupling theory can provide a physically meaningful interpretation of the anomalous diffusivity of polyatomic ions in water, by including the contribution of rotational jumps on translational friction...
September 28, 2017: Journal of Chemical Physics
#10
Costantino Masciopinto, Fabrizio Visino
Effluents derived from a municipal wastewater treatment plant were used for virus filtration/retention experiments by using a horizontal laboratory filter. Filtration tests were performed to examine how soil geochemical heterogeneity and fracture patterns affected the transport of viruses in groundwater in order to model the influence of reductive perturbations in ionic strength (IS) during wastewater filtration. Although perturbations of IS and velocity are known to result in resuspension of colloids, we found that the effect of soil geochemical heterogeneity can produce strong and instantaneous virus releases in fractured aquifers, likely an internal additional source of viruses...
September 20, 2017: Water Research
#11
Abhilash Chandra, Prabhat Kumar Sahu, Subhayan Chakraborty, Arindam Ghosh, Moloy Sarkar
The present study has been undertaken with an aim to investigate the suitability of the deep eutectic solvents (DES)-based systems for magnetic resonance imaging (MRI) studies. DESs are used to develop the systems keeping in mind the fact that these are relatively less toxic than ionic liquids, and hence, DES based magnetic compound is expected to be relatively less toxic than magnetic ionic liquids. In this work spin-lattice (T1 ) relaxation measurements are carried out in the binary mixtures of deep eutectic solvent with a paramagnetic component choliniumtetrachloroferrate ([Ch][FeCl4 ])...
September 28, 2017: Magnetic Resonance in Chemistry: MRC
#12
Pengfei Niu, Brian J Nablo, Kiran Bhadriraju, Darwin R Reyes
Changes in electrical impedance have previously been used to measure fluid flow rate in microfluidic channels. Ionic redistribution within the electrical double layer by fluid flow has been considered to be the primary mechanism underlying such impedance based microflow sensors. Here we describe a previously unappreciated contribution of microchannel deformation to such measurements. We found that flow-induced microchannel deformation contributes significantly to the change in electrical impedance of solutions, in particular to those solutions producing an electrical double layer in the order of a few tens of nanometers (i...
September 29, 2017: Analytical Chemistry
#13
Junling Guo, Joseph J Richardson, Quinn A Besford, Andrew J Christofferson, Yunlu Dai, Chien W Ong, Blaise L Tardy, Kang Liang, Gwan H Choi, Jiwei Cui, Pil J Yoo, Irene Yarovsky, Frank Caruso
Metal-phenolic networks (MPNs) are a versatile class of self-assembled materials that are able to form functional thin films on various substrates with potential applications in areas including drug delivery and catalysis. Different metal ions (e.g., Fe(III), Cu(II)) and phenols (e.g., tannic acid, gallic acid) have been investigated for MPN film assembly; however, a mechanistic understanding of the thermodynamics governing MPN formation remains largely unexplored. To date, MPNs have been deposited at low ionic strengths (<5 mM), resulting in films with typical thicknesses of ∼10 nm, and it is still unclear how a bulk complexation reaction results in homogeneous thin films when a substrate is present...
September 27, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
#14
Christopher P Cabry, Lucía D'Andrea, Karina Shimizu, Isabelle Grillo, Peixun Li, Sarah Rogers, Duncan W Bruce, José N Canongia Lopes, John M Slattery
Small-angle neutron scattering experiments, supported by molecular dynamics simulations, have been performed on a range of compositions of the [C2mim]1-x[C12mim]x[Tf2N] ionic liquid mixture system. Isotopic contrast variation, through selective deuteration of both cations, has been used to assist in fitting the data to different scattering models. These data, and subsequent fitting, show that the structure of the ionic liquid mixtures changes substantially as a function of composition. Mixtures where x < 0...
#15
Vuk Uskoković, Maheshwar Adiraj Iyer, Victoria M Wu
Although hydroxyapatite (HAp) has been doped with dozens of different ions, the quest for an ion imparting a combination of properties conducive to bone healing is still ongoing. Because of its protean potency and the similarity in size and shape to the phosphate tetrahedron, selenite ion presents a natural ionic substitute in HAp. The incorporation of selenite into synthetic HAp using two different methods - co-precipitation and ion-exchange sorption - was studied for its effect on crystal properties and on a triad of biological responses: antibacterial, anticancer and osteoinductive...
2017: Journal of Materials Chemistry. B, Materials for Biology and Medicine
#16
Gabriela Kania, Magdalena Sternak, Agnieszka Jasztal, Stefan Chlopicki, Agnieszka Błażejczyk, Anna Nasulewicz-Goldeman, Joanna Wietrzyk, Krzysztof Jasiński, Tomasz Skórka, Szczepan Zapotoczny, Maria Nowakowska
Bioreactivity of superparamagnetic iron oxide nanoparticles (SPION) coated with thin layers of either cationic or anionic chitosan derivatives and serving as contrast agents in magnetic resonance imaging (MRI) was studied in vivo using BALB/c mouse model. Synthesized dual-modal fluorescing SPION were tracked in time using both fluorescent imaging and MRI. Although SPION started to be excreted by kidneys relatively shortly after administration they were uptaken by liver enhancing MRI contrast even up to 7 days...
September 19, 2017: Nanomedicine: Nanotechnology, Biology, and Medicine
#17
Ryo Kanzaki, Shuma Uchida, Hitoshi Kodamatani, Takashi Tomiyasu
Metal ions in ionic liquids are laid under an unprecedented reaction field. In order to assess the reaction thermodynamics of metal ions in such a situation, Cu(2+)-chloro complex formation was examined with spectroscopic and calorimetric titrations in an ionic liquid, 1-buthyl-3-methylimidazolium trifluoromethanesulfonate (C4mimTfO). In addition, the effect of the structure of the solvated complexes on the complexation mechanism was investigated with the aid of DFT calculations. Chloro complexation successively proceeded and finally provided a [CuCl4](2-) species, which is also the final product in conventional molecular solvents...
October 4, 2017: Journal of Physical Chemistry. B
#18
C Bodin, E Mourad, D Zigah, S Le Vot, S A Freunberger, F Favier, O Fontaine
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., RuO2, MnO2…) 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...
#19
Adan Li, Thang Phan Dinh, Tomoko Imasaka, Totaro Imasaka
The ionization and fragmentation processes for pentachlorobenzene were examined using a femtosecond laser emitting at 400, 800, and 1200 nm. A molecular ion was clearly observed in the mass spectrum, since the molecule can be directly ionized from the singlet electronic exited state before relaxation to triplet levels, because the pulse width of the laser is shorter than the lifetime of the excited state. Fragmentation was minimal at 1200 nm, in contrast to ionization at 800 and 400 nm. Indeed, a doubly-charged molecular ion was prominent at 800 nm, owing to the absorption band of the singly-charged molecular ion at this wavelength...
September 21, 2017: Analyst
#20
Romain Perriot, Blas P Uberuaga, Richard J Zamora, Danny Perez, Arthur F Voter
Diffusion in complex oxides is critical to ionic transport, radiation damage evolution, sintering, and aging. In complex oxides such as pyrochlores, anionic diffusion is dramatically affected by cation disorder. However, little is known about how disorder influences cation transport. Here, we report results from classical and accelerated molecular dynamics simulations of vacancy-mediated cation diffusion in Gd2Ti2O7 pyrochlore, on the microsecond timescale. We find that diffusion is slow at low levels of disorder, while higher disorder allows for fast diffusion, which is then accompanied by antisite annihilation and reordering, and thus a slowing of cation transport...
September 20, 2017: Nature Communications
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