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https://www.readbyqxmd.com/read/28089275/microfluidic-membrane-suppressor-module-design-and-evaluation-for-capillary-ion-chromatography
#1
Sam Wouters, Cees Bruggink, Yury Agroskin, Christopher Pohl, Sebastiaan Eeltink
A microfluidic ion-suppression module for use in ion-exchange chromatography has been developed and evaluated. The device consists of an ion-exchange membrane clamped between two polymer chips featuring a 200×100μm (width×depth) eluent channel (l=60mm), and a 300×150μm regenerant channel (60mm), respectively. The suppression efficacy using a Nafion membrane was compared with that of a styrene-sulfonate grafted fluorinated ethylene propylene (FEP) membrane. The latter was found to outperform Nafion in terms of lowest attainable background signal (suppression efficacy) and dynamic suppression range...
December 29, 2016: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28081476/electron-spin-relaxation-of-a-boron-containing-heterocyclic-radical
#2
Sandra S Eaton, Kirby Huber, Hanan Elajaili, Joseph McPeak, Gareth R Eaton, Lauren E Longobardi, Douglas W Stephan
Preparation of the stable boron-containing heterocyclic phenanthrenedione radical, (C6F5)2B(O2C14H8), by frustrated Lewis pair chemistry has been reported recently. Electron paramagnetic resonance measurements of this radical were made at X-band in toluene:dichloromethane (9:1) from 10 to 293K, in toluene from 180 to 293K and at Q-band at 80K. In well-deoxygenated 0.1mM toluene solution at room temperature hyperfine splittings from (11)B, four pairs of (1)H, and 5 pairs of (19)F contribute to an EPR spectrum with many resolved lines...
December 30, 2016: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28079964/bab-random-c-monomer-sequence-via-radical-terpolymerization-of-limonene%C3%A2-a-maleimide%C3%A2-b-and-methacrylate%C3%A2-c-terpene-polymers-with-randomly-distributed-periodic-sequences
#3
Masataka Ojika, Kotaro Satoh, Masami Kamigaito
A naturally abundant terpene, limonene (A), was radically polymerized with a maleimide derivative (B) and methacrylate (C) in a fluorinated alcohol to give terpolymers with unprecedented BAB-random-C sequences in which the BAB monomer sequence was randomly copolymerized with a C unit. In each binary system, limonene was hardly copolymerized with methacrylate while it was efficiently copolymerized with maleimide to result in a 1:2-alternating BAB periodic sequence, in part due to the penultimate effects and hydrogen-bonding interactions with fluoroalcohol...
January 12, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28079219/internal-dynamics-in-helical-molecules-studied-by-x-ray-diffraction-nmr-spectroscopy-and-dft-calculations
#4
Martin Dračínský, Jan Storch, Vladimír Církva, Ivana Císařová, Jan Sýkora
The conformational behaviour of a prototype helical molecule, [6]helicene, and its derivatives was studied in solution and the solid state. Available crystal structures of [6]helicene revealed surprisingly large flexibility of this molecule and variable-temperature NMR experiments provided unusual temperature dependence of chemical shifts of hydrogen, carbon and fluorine atoms in the peripheral aromatic rings of [6]helicene and tetrafluoro[6]helicene. These chemical shift changes were interpreted as a consequence of the helicene 'pitch' opening with elevated temperature, and the experimental data were corroborated by DFT calculations of the chemical shift dependence on the helicene conformation and by variable-temperature DFT molecular dynamics simulations...
January 12, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28074938/sprayable-superhydrophobic-nano-chains-coating-with-continuous-self-jumping-of-dew-and-melting-frost
#5
Shanlin Wang, Wenwen Zhang, Xinquan Yu, Caihua Liang, Youfa Zhang
Spontaneous movement of condensed matter provides a new insight to efficiently improve condensation heat transfer on superhydrophobic surface. However, very few reports have shown the jumping behaviors on the sprayable superhydrophobic coatings. Here, we developed a sprayable silica nano-porous coating assembled by fluorinated nano-chains to survey the condensates' dynamics. The dewdrops were continuously removed by self- and/or trigger-propelling motion due to abundant nano-pores from random multilayer stacking of nano-chains...
January 11, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28074490/rationally-designed-blue-triplet-emitting-gold-iiii-complexes-based-on-phenylpyridine-derived-framework
#6
Michael Bachmann, Jasmin Terreni, Olivier Blacque, Koushik Venkatesan
A series of blue emitting phosphorescent monocyclometalated Au(III) complexes were successfully synthesized. Tailoring substitutions at the phenylpyridine (ppy) ligand scaffold with the electron withdrawing fluorine groups at the phenyl ring to achieve stabilization of the HOMO and electron donating dimethylamino group on the pyridine ring to destabilize the LUMO resulted in a large energy gap and bestowed the gold(III) complexes with emission at high energies and high quantum efficiencies. Cyclic voltammetry (CV) studies are suggestive of a predominantly cyclometalated ligand localized redox event...
January 10, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28073630/adona-and-perfluoroalkylated-substances-in-plasma-samples-of-german-blood-donors-living-in-south-germany
#7
Hermann Fromme, Mandy Wöckner, Eike Roscher, Wolfgang Völkel
Perfluorinated compounds are fully fluorinated anthropogenic substances that have been used in various products, applications, and industrial processes. Due to their persistence and toxic effects, some of them are restricted, and therefore replacement products have been developed. The aim of the study was to quantify the body burden of different perfluorinated substances in two adult populations living close to or about 80km apart from a former perfluorooctanoate (PFOA) production plant who are exposed via drinking water, and in a control population...
January 4, 2017: International Journal of Hygiene and Environmental Health
https://www.readbyqxmd.com/read/28072890/candida-albicans-survival-growth-and-biofilm-formation-are-differently-affected-by-mouthwashes-an-in-vitro-study
#8
Simona Paulone, Giulia Malavasi, Andrea Ardizzoni, Carlotta Francesca Orsi, Samuele Peppoloni, Rachele Giovanna Neglia, Elisabetta Blasi
Candida albicans is the most common cause of oral mycoses. The aim of the present study was to investigate in vitro the susceptibility of C. albicans to mouthwashes, in terms of growth, survival and biofilm formation. Candida albicans, laboratory strain SC5314, and 7 commercial mouthwashes were employed: 3 with 0.2% chlorhexidine digluconate; 1 with 0.06% chlorhexidine digluconate and 250 ppm F- sodium fluoride; 3 with fluorine-containing molecules. None of the mouthwashes contained ethanol in their formulations...
January 9, 2017: New Microbiologica
https://www.readbyqxmd.com/read/28071901/accurate-theoretical-thermochemistry-for-fluoroethyl-radicals
#9
Adam Ganyecz, Mihaly Kallay, Jozsef Csontos
An accurate coupled-cluster (CC) based model chemistry was applied to calculate reliable thermochemical quantities for hydrofluorocarbon hydrofluorocarbon derivatives including radicals 1-fluoroethyl (CH3 -CHF), 1,1-difluoroethyl (CH3-CF2), 2-fluoroethyl (CH2F-CH2), 1,2-difluoroethyl (CH2F-CHF), 2,2-difluoroethyl (CHF2-CH2), 2,2,2-trifluoroethyl (CF3-CH2), 1,2,2,2-tetrafluoroethyl (CF3-CHF), and pentafluoroethyl (CF3-CF2). The model chemistry used contains iterative triple and perturbative quadruple excitations in CC theory, as well as scalar relativistic and diagonal Born-Oppenheimer corrections...
January 10, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28071849/activation-of-the-b-f-bond-by-diphenylcarbene-a-reversible-1-2-fluorine-migration-between-boron-and-carbon
#10
Paolo Costa, Joel Mieres Perez, Nesli Özkan, Wolfram Sander
Experiments in low-temperature matrices reveal that triplet diphenylcarbene inserts into the very strong B-F bond of BF3 in a two-step reaction. The first step is the formation of a strongly bound Lewis acid-base complex between the singlet state of diphenylcarbene and BF3 . This step involves an inversion of the spin state of the carbene from triplet to singlet. The second step requires visible-light photochemical activation to induce a 1,2-F migration from boron to the adjacent carbon atom under formation of the formal insertion product of the carbene center into BF3 ...
January 10, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28071049/stereochemically-defined-various-multi-substituted-alkenes-bearing-a-tetrafluoroethylene-cf2cf2-fragment
#11
Yukiho Sakaguchi, Shigeyuki Yamada, Tsutomu Konno, Tomohiro Agou, Toshio Kubota
Highly regio- and stereoselective transformation of commercially available 4-bromo-3,3,4,4-tetrafluoro-1-butene into multisubstituted alkenes having a tetrafluoroethylene fragment through Heck reaction and/or Suzuki-Miyaura cross coupling reaction was established. Thus obtained alkenes underwent a smooth reductive coupling reaction with aldehydes under the influence of MeLi/LiBr-free, affording structurally unprecedented fluorinated materials.
January 10, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28068093/correlation-energy-extrapolation-by-many-body-expansion
#12
Jeffery S Boschen, Daniel Theis, Klaus Ruedenberg, Theresa L Windus
Accounting for electron correlation is required for high accuracy calculations of molecular energies. The full configuration interaction (CI) approach can fully capture the electron correlation within a given basis, but it does so at a computational expense which is impractical for all but the smallest chemical systems. In this work, a new methodology is presented to approximate configuration interaction calculations at a reduced computational expense and memory requirement, namely the Correlation Energy Extrapolation by Many-Body Expansion (CEEMBE)...
January 9, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28067487/investigation-into-pseudo-capacitance-behavior-of-glycoside-containing-hydrogels
#13
Nachiket R Raravikar, Andrew Dobos, Eshwaran Narayanan, Taraka Sai Pavan Grandhi, Saurabh Mishra, Kaushal Rege, Michael Goryll
Electrochemical pseudo-capacitors are an attractive choice for energy storage applications because they offer higher energy densities than electrostatic or electric double layer capacitors. They also offer higher power densities in shorter durations of time, as compared to batteries. Recent efforts on pseudo-capacitors include biocompatible hydrogel electrolytes and transition metal electrodes for implantable energy storage applications. Pseudo-capacitive behavior in these devices has been attributed to the redox reactions that occur within the electric double layer, which is formed at the electrode-electrolyte interface...
January 9, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28067453/fluoride-anion-complexation-by-a-triptycene-based-distiborane-taking-advantage-of-a-weak-but-observable-c-h%C3%A2-%C3%A2-%C3%A2-f-interaction
#14
Chang-Hong Chen, François P Gabbaï
Fluoride anion complexation impacts a number of areas ranging from sensing to nucleophilic fluorination chemistry. Described here is a new bidentate Lewis acid consisting of two stiborane units connected by a 1,8-triptycenediyl backbone. This neutral derivative captures fluoride with an unprecedented affinity for a neutral, water-compatible Lewis acid. Structural, spectroscopic and computational studies demonstrate that fluoride anion binding is assisted by the formation of a C-H⋅⋅⋅F hydrogen bond which involves a methine group of the 1,8-triptycenediyl backbone...
January 9, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28067301/fluorine-free-electrolytes-for-all-solid-sodium-ion-batteries-based-on-percyano-substituted-organic-salts
#15
Anna Bitner-Michalska, Gene M Nolis, Grażyna Żukowska, Aldona Zalewska, Marcin Poterała, Tomasz Trzeciak, Maciej Dranka, Michał Kalita, Piotr Jankowski, Leszek Niedzicki, Janusz Zachara, Marek Marcinek, Władysław Wieczorek
A new family of fluorine-free solid-polymer electrolytes, for use in sodium-ion battery applications, is presented. Three novel sodium salts withdiffuse negative charges: sodium pentacyanopropenide (NaPCPI), sodium 2,3,4,5-tetracyanopirolate (NaTCP) and sodium 2,4,5-tricyanoimidazolate (NaTIM) were designed andtested in a poly(ethylene oxide) (PEO) matrix as polymer electrolytes for anall-solid sodium-ion battery. Due to unique, non-covalent structural configurations of anions, improved ionic conductivities were observed...
January 9, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28064006/versatile-rna-tetra-u-helix-linking-motif-as-a-toolkit-for-nucleic-acid-nanotechnology
#16
My N Bui, M Brittany Johnson, Mathias Viard, Emily Satterwhite, Angelica N Martins, Zhihai Li, Ian Marriott, Kirill A Afonin, Emil F Khisamutdinov
RNA nanotechnology employs synthetically modified ribonucleic acid (RNA) to engineer highly stable nanostructures in one, two, and three dimensions for medical applications. Despite the tremendous advantages in RNA nanotechnology, unmodified RNA itself is fragile and prone to enzymatic degradation. In contrast to use traditionally modified RNA strands e.g. 2'-fluorine, 2'-amine, 2'-methyl, we studied the effect of RNA/DNA hybrid approach utilizing a computer-assisted de novo RNA tetra-uracil (tetra-U) motif as a toolkit to address questions related to assembly efficiency, versatility, stability, and the production costs of hybrid RNA/DNA nanoparticles...
January 4, 2017: Nanomedicine: Nanotechnology, Biology, and Medicine
https://www.readbyqxmd.com/read/28061499/primary-intracranial-malignant-melanoma-with-extracranial-metastasis
#17
Kengo Hirota, Chika Yoshimura, Osami Kubo, Hidetoshi Kasuya
We report a case of primary intracranial malignant melanoma (PIMM) with extracranial metastases. The patient was an 82-year-old woman diagnosed with PIMM under the left cerebellar tentorium. We performed a tumor resection followed by gamma knife surgery. An magnetic resonance imaging at 11 months after surgery showed a local intracranial recurrence. At 12 months, vertebral metastasis was suspected, and 2-[fluorine-18]-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (FDG-PET/CT) showed multiple extracranial metastases...
January 1, 2017: Journal of Korean Neurosurgical Society
https://www.readbyqxmd.com/read/28060477/in-situ-localized-growth-of-ordered-metal-oxide-hollow-sphere-array-on-microheater-platform-for-sensitive-ultra-fast-gas-sensing
#18
Ameya Rao, Hu Long, Anna Harley-Trochimczyk, Thang Pham, Alex Zettl, Carlo Carraro, Roya Maboudian
A simple and versatile strategy is presented for the localized on-chip synthesis of an ordered metal oxide hollow sphere array directly on a low power microheater platform to form a closely integrated miniaturized gas sensor. Selective microheater surface modification through fluorinated monolayer self-assembly and its subsequent microheater-induced thermal decomposition enables the position-controlled deposition of an ordered two-dimensional colloidal sphere array, which serves as a sacrificial template for metal oxide growth via homogeneous chemical precipitation; this strategy ensures control in both the morphology and placement of the sensing material on only the active heated area of the microheater platform, providing a major advantage over other methods of presynthesized nanomaterial integration via suspension coating or printing...
January 13, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28059503/fused-nonacyclic-electron-acceptors-for-efficient-polymer-solar-cells
#19
Shuixing Dai, Fuwen Zhao, Qianqian Zhang, Tsz-Ki Lau, Tengfei Li, Kuan Liu, Qidan Ling, Chunru Wang, Xinhui Lu, Wei You, Xiaowei Zhan
We design and synthesize four fused-ring electron acceptors based on 6,6,12,12-tetrakis(4-hexylphenyl)-indacenobis(dithieno[3,2-b;2',3'-d]thiophene) as the electron-rich unit and 1,1-dicyanomethylene-3-indanones with 0 to 2 fluorine substituents as the electron-deficient units. These four molecules exhibit broad (550-850 nm) and strong absorption with high extinction coefficients of (2.1-2.5) ×10(5) M(-1) cm(-1). Fluorine substitution down shifts LUMO energy level, red shift absorption spectrum, and enhance electron mobility...
January 6, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28058429/positional-effects-of-fluorination-in-conjugated-side-chains-on-photovoltaic-properties-of-donor-acceptor-copolymers
#20
Jisoo Shin, Min Kim, Jaewon Lee, Heung Gyu Kim, Hyeongjin Hwang, Kilwon Cho
The position at which conjugated side chains were fluorinated, the meta- or ortho-position in phenyl side chains, was varied to investigate the positional effects of fluorination on the energy levels, crystalline ordering, and photovoltaic properties of the polymers. The fluorine in the ortho-position achieved a lower HOMO energy level than that in the meta-position, but reduced the chain rigidity.
January 6, 2017: Chemical Communications: Chem Comm
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