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electrolyte and acid-base

M Antonietta Baldo, Paolo Oliveri, Remo Simonetti, Salvatore Daniele
In this paper, a novel voltammetric/amperometric approach for the direct determination of free acidity (FFA, expressed as mass percentage of free oleic acid) in olive oil samples is presented. The method is based on the reduction processes occurring at a platinum microdisk electrode involving the free fatty acids present in the matrices. To overcome problems related to the low conductivity of the samples investigated, olive oils were mixed with suitable amounts of the room temperature ionic liquid (RTIL), tri-hexyl(tetradecyl)phosphonium bis (trifluoromethylsulfonyl) imide ([P14,6,6,6](+)[NTf2](-)), which acted as a supporting electrolyte...
December 1, 2016: Talanta
Lee Yien Thang, Hong Heng See, Joselito P Quirino
The low conductivity of separation electrolytes employed in nonaqueous capillary electrophoresis (NACE) limits the use of on-line sample concentration or stacking by field enhancement. Herein, micelle-to-solvent stacking (MSS) was performed by the simple injection of a micellar solution plug prior to electrokinetic injection of sample prepared under field-enhanced stacking conditions (known as field-enhanced sample injection, FESI). The proposed approach allowed a 214-625-fold improvement in peak signals for targeted anticancer drugs (e...
December 1, 2016: Talanta
Eui Jin Lee, Jae Pil Han, Seung Eun Jung, Min Hee Choi, Doo Kyung Moon
In this study, we fabricated conventional structured organic solar cells (OSCs) by introducing a hole extraction layer (HEL) that consisted of poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) and conjugated polymer electrolyte (CPE) poly[9,9-bis(4'-sulfonatobutyl)fluorene-alt-thiophene] (PFT-D). PFT-D has a -SO3(-) functional group that acts as a conjugate base against the -SO3H of PSS. In addition, the molecular dipole of PFT-D can screen the coulombic attraction between PEDOT chains and PSS chains...
October 21, 2016: ACS Applied Materials & Interfaces
Tobias Janoschka, Norbert Martin, Martin D Hager, Ulrich S Schubert
Redox-flow batteries (RFB) can easily store large amounts of electric energy and thereby mitigate the fluctuating output of renewable power plants. They are widely discussed as energy-storage solutions for wind and solar farms to improve the stability of the electrical grid. Most common RFB concepts are based on strongly acidic metal-salt solutions or poorly performing organics. Herein we present a battery which employs the highly soluble N,N,N-2,2,6,6-heptamethylpiperidinyl oxy-4-ammonium chloride (TEMPTMA) and the viologen derivative N,N'-dimethyl-4,4-bipyridinium dichloride (MV) in a simple and safe aqueous solution as redox-active materials...
October 18, 2016: Angewandte Chemie
Carolina López, Andrés José Alcaraz, Blanca Toledo, Lucía Cortejoso, Maite Augusta Gil-Ruiz
OBJECTIVE: Patients in PICUs frequently present hypochloremic metabolic alkalosis secondary to loop diuretic treatment, especially those undergoing cardiac surgery. This study evaluates the effectiveness of acetazolamide therapy for metabolic alkalosis in PICU patients. DESIGN: Retrospective, observational study. SETTING: A tertiary care children's hospital PICU. PATIENTS: Children receiving at least a 2-day course of enteral acetazolamide...
September 29, 2016: Pediatric Critical Care Medicine
Robert Sümpelmann, Karin Becke, Sebastian Brenner, Christian Breschan, Christoph Eich, Claudia Höhne, Martin Jöhr, Franz-Josef Kretz, Gernot Marx, Lars Pape, Markus Schreiber, Jochen Strauss, Markus Weiss
This consensus- based S1 Guideline for perioperative infusion therapy in children is focused on safety and efficacy. The objective is to maintain or re-establish the child's normal physiological state (normovolemia, normal tissue perfusion, normal metabolic function, normal acid- base- electrolyte status). Therefore, the perioperative fasting times should be as short as possible to prevent patient discomfort, dehydration, and ketoacidosis. A physiologically composed balanced isotonic electrolyte solution (BS) with 1-2...
October 17, 2016: Paediatric Anaesthesia
Wei Zhou, Yen-Ling Liu, Audrey M Stallworth, Chunsong Ye, John J Lenhart
We investigated the evolution in silver nanoparticle (AgNP) properties during a series of 10 - 50 day experiments on suspensions with different pH (5 - 9), electrolyte type (NaNO3 and NaCl) and concentration (2 mM and 6 mM), Suwanee River humic acid (SRHA) concentration (0 - 13.2 mg C/L) and light exposure (artificial sun light exposure for 8h per day or dark). Of these factors, pH most influenced the AgNPs' properties as it modifies surface charge as well as AgNP dissolution and oxidation, and Ag+ reduction reactions...
October 14, 2016: Environmental Science & Technology
Piotr Kowalski, Ilona Olędzka, Alina Plenis, Tomasz Bączek
An indirect UV detection method based on capillary electrophoresis was developed and validated to determinate 12. metal cations, including alkali, alkaline earth, transition metal, and ammonium. In this paper a new electrolyte system (pH 4.22) contained 20 mM benzimidazole (as co-ion), 75 mM acetic acid (as a counter-ion) as well as 0.6 mM 18-crown-6 ether was applied. The metal ions were completely separated within 8 min under hydrodynamic mode injection with a running voltage of 20 kV at 25 ± 0.1°C. Additional use of the dynamic double coating method enabled to get an excellent repeatability of migration times and quantitative parameters for all analytes...
October 14, 2016: Electrophoresis
Benjamin W Noffke, Qiqi Li, Krishnan Raghavachari, Liang-Shi Li
Nitrogen-doped graphitic carbon materials have been extensively studied as potential replacements for Pt-based electrocatalysts for the oxygen reduction reaction (ORR). However, little is known about the catalytic mechanisms, including the parameters that determine the selectivity of the reaction. By comparing theoretical calculations of the ORR selectivity at a well-defined graphene nanostructure with experimental results, we propose a model based on interfacial solvation to explain the observed preference for the four-electron pathway in alkaline electrolytes...
October 13, 2016: Journal of the American Chemical Society
Poul Erik Hansen, Torben Lund, Jacob Krake, Jens Spanget-Larsen, Soren Hvidt
The complex between diisopropylethylamine (DIPEA) and formic acid has been reinvestigated. Mixing the compounds in the ratio 1:1 leads to a phase separation in which the upper phase is DIPEA, the lower phase is the "ionic liquid" named DIPEF. A combined NMR and DFT study shows that the lower phase primarily is formic acid:formate and diisopropylammonium ions in the ratio 2:1 (acid:base) plus the formic acid dimer. Addition of more acid leads to more and more of the acid dimer. The proton transfer in the system is ~ 0...
October 12, 2016: Journal of Physical Chemistry. B
M-C Horny, M Lazerges, J-M Siaugue, A Pallandre, D Rose, F Bedioui, C Deslouis, A-M Haghiri-Gosnet, J Gamby
Here, we describe the transposition of an ultramicroelectrode (UME) setup into a microfluidic chip configuration for DNA biosensors. The hydrodynamic properties of the fluidic channel microelectrode were screened with an [Fe(iii)(CN)6](3-)/[Fe(ii)(CN)6](4-) redox couple by cyclic voltammetry to provide a basis for further biological processes. A 23-base DNA probe was self-assembled into a monolayer on gold microelectrodes both in classical configuration and integrated in a microfluidic setup. Special interest was focused on the DNA target mimicking the liver-specific micro-ribonucleic acid 122 (miRNA122)...
October 10, 2016: Lab on a Chip
Jennifer G Jetton, Mark Sorenson
Both acute kidney injury (AKI) and chronic kidney disease (CKD) are seen more frequently in the neonatal intensive care unit (NICU) as advances in supportive care improve the survival of critically ill infants as well as those with severe, congenital kidney and urinary tract anomalies. Many aspects of the infant's care, including fluid balance, electrolyte and mineral homeostasis, acid-base balance, and growth and nutrition require close monitoring by and collaboration among neonatologists, nephrologists, dieticians, and pharmacologists...
October 6, 2016: Seminars in Fetal & Neonatal Medicine
Hang Yao, Priti Azad, Huiwen W Zhao, Juan Wang, Orit Poulsen, Beatriz C Freitas, Alysson R Muotri, Gabriel G Haddad
The sodium bicarbonate co-transporter (NBC) is the major bicarbonate-dependent acid-base transporter in mammalian astrocytes and has been implicated in ischemic brain injury. A malfunction of astrocytes could have great impact on the outcome of stroke due to their participation in the formation of blood-brain barrier, synaptic transmission, and electrolyte balance in the human brain. Nevertheless, the role of NBC in the ischemic astrocyte death has not been well understood. In this work, we obtained skin biopsies from healthy human subjects and had their fibroblasts grown in culture and reprogrammed into human-induced pluripotent stem cells (hiPSCs)...
October 4, 2016: Neuroscience
Mingxing Tu, Xianhang Wang, Tongying Feng, Xiaomeng Sun, Yaqiong Wang, Li Huang, Min Gao, Yuejin Wang, Xiping Wang
Drought is one of the most serious factors that limit agricultural productivity and there is considerable interest in understanding the molecular bases of drought responses and their regulation. While numbers of basic leucine zipper (bZIP) transcription factors (TFs) are known to play key roles in response of plants to various abiotic stresses, only a few group K bZIP TFs have been functionally characterized in the context of stress signaling. In this study, we characterized the expression of the grape (Vitis vinifera) group K bZIP gene, VlbZIP36, and found evidence for its involvement in response to drought and the stress-associated phytohormone abscisic acid (ABA)...
November 2016: Plant Science: An International Journal of Experimental Plant Biology
Kazuhisa Isegawa, Tetsuo Nagami, Shinji Jomori, Masaaki Yoshida, Hiroshi Kondoh
Changes in the chemical states of sulfonic groups of Nafion in polymer electrolyte fuel cells (PEFCs) under gas-flowing conditions were studied using in situ S-K XANES spectroscopy. The applied potential to the electrodes and the humidity of the cell were changed under flowing H2 gas in the anode and He gas in the cathode. While the potential shows no significant effect on the S-K XANES spectra, the humidity is found to induce reversible changes in the spectra. Comparison of the spectral changes with simulations based on the density functional theory calculations indicates that the humidity influences the chemical state of the sulfonic group; under wet conditions the sulfonic group is in the form of a sulfonate ion...
September 14, 2016: Physical Chemistry Chemical Physics: PCCP
Youcef A Bioud, Abderraouf Boucherif, Ali Belarouci, Etienne Paradis, Dominique Drouin, Richard Arès
We have performed a detailed characterization study of electrochemically etched p-type GaAs in a hydrofluoric acid-based electrolyte. The samples were investigated and characterized through cathodoluminescence (CL), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). It was found that after electrochemical etching, the porous layer showed a major decrease in the CL intensity and a change in chemical composition and in the crystalline phase. Contrary to previous reports on p-GaAs porosification, which stated that the formed layer is composed of porous GaAs, we report evidence that the porous layer is in fact mainly constituted of porous As2O3...
December 2016: Nanoscale Research Letters
Anna Takácsi-Nagy, Ferenc Kilár, Wolfgang Thormann
This paper comprises a continuation of computer simulation studies dealing with carrier ampholyte based CIEF in presence of narrow pH gradients. With this technique, amphoteric sample components with pI values outside the pH gradient are migrating isotachophoretically toward the cathode or anode whereas components with pI values within the gradient become focused. In order to understand the processes occurring in presence of the electric field, the behavior of both carrier ampholytes and amphoteric sample components is investigated by computer modeling...
October 4, 2016: Electrophoresis
Henrik Harnisch, Jens Hühner, Christian Neusüß, Andreas Koschella, Thomas Heinze, Gerhard K E Scriba
To characterize sulfoethyl cellulose samples, a capillary electrophoresis method was developed and validated. Sulfoethyl cellulose was hydrolyzed, and the resulting d-glucose derivatives were analyzed after reductive amination with 4-aminobenzoic acid using 150 mM boric acid, pH 9.5, as background electrolyte at 20°C and a voltage of 28 kV. Peak identification was derived from capillary electrophoresis with mass spectrometry using 25 mM ammonia adjusted to pH 6.2 by acetic acid as electrolyte. Besides mono-, di- and tri-sulfoethyl-d-glucose, small amounts of disaccharides could be identified resulting from incomplete hydrolysis...
October 3, 2016: Journal of Separation Science
Mei-Fang Li, Yun-Guo Liu, Guang-Ming Zeng, Shao-Bo Liu, Xin-Jiang Hu, Ding Shu, Lu-Hua Jiang, Xiao-Fei Tan, Xiao-Xi Cai, Zhi-Li Yan
A novel magnetic nanomaterial was synthesized by grafting nitrilotriacetic acid to magnetic graphene oxide (NDMGO), which was applied as an adsorbent for removing tetracycline (TC) from aqueous solutions. The nanomaterial was characterized using TG-DTA, SEM, TEM, XRD, VSM, XPS, Raman, BET surface area and zeta potential measurements. Several experimental conditions (solution pH, adsorption time, temperature, ionic strength and foreign ions) affecting the adsorption process were investigated. The results showed that the TC adsorption capacity could be affected by solution pH...
January 1, 2017: Journal of Colloid and Interface Science
Lu-Ting Song, Zhen-Yu Wu, Fei Zhou, Hai-Wei Liang, Zi-You Yu, Shu-Hong Yu
It is urgent to develop new kinds of low-cost and high-performance nonprecious metal (NPM) catalysts as alternatives to Pt-based catalysts for oxygen reduction reaction (ORR) in fuel cells and metal-air batteries, which have been proved to be efficient to meet the challenge of increase of global energy demand and CO2 emissions. Here, an economical and sustainable method is developed for the synthesis of Fe, N codoped carbon nanofibers (Fe-N/CNFs) aerogels as efficient NPM catalysts for ORR via a mild template-directed hydrothermal carbonization (HTC) process, where cost-effective biomass-derived d(+)-glucosamine hydrochloride and ferrous gluconate are used as precursors and recyclable ultrathin tellurium nanowires are used as templates...
September 27, 2016: Small
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