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https://www.readbyqxmd.com/read/29907978/effects-of-the-substituents-of-boron-atoms-on-conjugated-polymers-containing-b%C3%A2-n-units
#1
Jun Liu, Tao Wang, Chuandong Dou, Lixiang Wang
Organoboron chemistry is a new tool to tune the electronic structures and properties of conjugated polymers, which are important for applications in organic opto-electronic devices. To investigate the effects of substituents of boron atoms on conjugated polymers, we synthesized three conjugated polymers based on double B←N bridged bipyridine (BNBP) with various substituents on the boron atoms. By changing the substituents from four phenyl groups and two phenyl groups/two fluorine atoms to four fluorine atoms, the BNBP-based polymers show the blue-shifted absorption spectra, decreased LUMO/HOMO energy levels and enhanced electron affinities, as well as the increased electron mobilities...
June 15, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29907834/a-novel-metamaterial-inspired-rf-coil-for-preclinical-dual-nuclei-mri
#2
Anna Hurshkainen, Anton Nikulin, Elodie Georget, Benoit Larrat, Djamel Berrahou, Ana Luisa Neves, Pierre Sabouroux, Stefan Enoch, Irina Melchakova, Pavel Belov, Stanislav Glybovski, Redha Abdeddaim
In this paper, we propose, design and test a new dual-nuclei RF-coil inspired by wire metamaterial structures. The coil operates as a result of resonant excitation of hybridized eigenmodes in multimode flat periodic structures comprising several coupled thin metal strips. It was shown that the field distribution of the coil (i.e. penetration depth) can be controlled independently at two different Larmor frequencies by selecting a proper eigenmode in each of two mutually orthogonal periodic structures. The proposed coil requires no lumped capacitors to be tuned and matched...
June 15, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29905751/remote-functionalization-in-surface-assisted-dehalogenation-by-conformational-mechanics-organometallic-self-assembly-of-3-3-5-5-tetrabromo-2-2-4-4-6-6-hexafluorobiphenyl-on-ag-111
#3
Matthias Lischka, Georg S Michelitsch, Natalia Martsinovich, Johanna Eichhorn, Atena Rastgoo-Lahrood, Thomas Strunskus, Rochus Breuer, Karsten Reuter, Michael Schmittel, Markus Lackinger
Even though the surface-assisted dehalogenative coupling constitutes the most abundant protocol in on-surface synthesis, its full potential will only become visible if selectivity issues with polybrominated precursors are comprehensively understood, opening new venues for both organometallic self-assembly and on-surface polymerization. Using the 3,3',5,5'-tetrabromo-2,2',4,4',6,6'-hexafluorobiphenyl (Br4F6BP) at Ag(111), we demonstrate a remote site-selective functionalization at room temperature and a marked temperature difference in double- vs...
June 15, 2018: Nanoscale
https://www.readbyqxmd.com/read/29905339/a-generalized-approach-for-nmr-studies-of-lipid-protein-interactions-based-on-sparse-fluorination-of-acyl-chains
#4
Alfredo De Biasio, Alain Ibáñez de Opakua, Mark J Bostock, Daniel Nietlispach, Tammo Diercks, Francisco J Blanco
Sparse lipid fluorination enhances the lipids' 1H signal dispersion, enables clean molecular distinction by 19F NMR, and evinces micelle insertion of proteins via fluorine-induced signal shifts. We present a minimal fluorination scheme, and illustrate the concept on di-(4-fluoro)-heptanoylphosphatidylcholine micelles and solubilised seven-helix transmembrane pSRII protein.
June 15, 2018: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/29904887/are-homoleptic-complexes-of-ethylene-with-group-12-metals-isolable-in-solution-a-dft-study
#5
Mauro Fianchini, Nuno A G Bandeira
Ethylene efficiently binds late transition metals of groups 10 and 11. In spite of their reactivity, homoleptic compounds of formula [M-(η2 -C2 H4 )3 ]n+ (with n = 0,1) have been isolated in solution and solid state and characterized spectroscopically throughout the last 50 years with metals from groups 10 and 11. X-ray diffraction studies proved that such homoleptic adducts adopt planar "wheel" structures where ethylene moieties lies flat in the same plane both in group 10 and 11. These experimental findings were also confirmed by several in-depth computational investigations carried out to understand the bond pattern of such peculiar structures...
June 14, 2018: Journal of Molecular Modeling
https://www.readbyqxmd.com/read/29904494/humeral-metastasis-of-sacrococcygeal-chordoma-detected-by-fluorine-18-fluorodeoxyglucose-positron-emission-tomography-computed-tomography-a-case-report
#6
Futao Cui, Minggang Su, Han Zhang, Rong Tian
Chordomas are rare, slow-growing, locally aggressive bone tumors arising from embryonic remnants of the notochord. Distant metastases most commonly involve the lung, liver, axial skeleton, skin, and lymph nodes. Humeral metastases are extremely rare. We report the case of a recurrent chordoma with humeral metastasis, complicated with pathologic fracture. Fluorine-18 fluorodeoxyglucose positron emission tomography-computed tomography revealed multiple hypermetabolic skeletal lesions, corresponding to the symptoms...
April 2018: Radiology Case Reports
https://www.readbyqxmd.com/read/29904142/rectification-and-negative-differential-resistance-via-orbital-level-pinning
#7
Aaron Zhenghui Thong, Milo S P Shaffer, Andrew P Horsfield
A donor-acceptor system, 4-thiophenyl-azafulleroid (4TPA-C60 ), is investigated at the point of HOMO/LUMO resonance and beyond to understand how negative differential resistance (NDR) features may be observed in such systems. Our previous investigation showed that charge transfer between the occupied and unoccupied states at resonance hindered crossing of the HOMO and LUMO levels, thus preventing the formation of an NDR feature. In this work, it is shown that the negative differential resistance feature of 4TPA-C60 can be tailored based on the couplings at the metal/molecule interface...
June 14, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29903537/predictors-of-positive-18-f-fdg-pet-ct-scan-for-large-vessel-vasculitis-in-patients-with-persistent-polymyalgia-rheumatica
#8
Diana Prieto-Peña, Isabel Martínez-Rodríguez, Javier Loricera, Ignacio Banzo, Mónica Calderón-Goercke, Vanesa Calvo-Río, Carmen González-Vela, Alfonso Corrales, Santos Castañeda, Ricardo Blanco, José L Hernández, Miguel Á González-Gay
OBJECTIVE: Polymyalgia rheumatica (PMR) is often the presenting manifestation of giant cell arteritis (GCA). Fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) scan often discloses the presence of large vessel vasculitis (LVV) in PMR patients. We aimed to identify predictive factors of a positive PET/CT scan for LVV in patients classified as having isolated PMR according to well-established criteria. METHODS: A set of consecutive patients with PMR from a single hospital were assessed...
May 18, 2018: Seminars in Arthritis and Rheumatism
https://www.readbyqxmd.com/read/29901992/effect-of-urine-compounds-on-the-electrochemical-oxidation-of-urea-using-a-nickel-cobaltite-catalyst-an-electroanalytical-and-spectroscopic-investigation
#9
Andrew F Schranck, Randal Marks, Elon Yates, Kyle Doudrick
Cyclic voltammetry (CV) and in-situ attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy were used to investigate the effect of major urine compounds on the electrooxidation activity of urea using a nickel cobaltite (NiCo2O4) catalyst. As a substrate, carbon paper exhibited better benchmark potential and current values compared to stainless steel and fluorine-doped tin oxide glass, which was attributed to its greater active surface area per electrode geometric area. CV analysis of a synthetic urine showed that phosphate, creatinine, and gelatin (i...
June 14, 2018: Environmental Science & Technology
https://www.readbyqxmd.com/read/29901488/decrease-in-total-lesion-glycolysis-and-survival-after-yttrium-90-radioembolization-in-poorly-differentiated-hepatocellular-carcinoma-with-portal-vein-tumour-thrombosis
#10
Luca Filippi, Giovan G Di Costanzo, Antonio D'Agostini, Raffaella Tortora, Giuseppe Pelle, Roberto Cianni, Orazio Schillaci, Oreste Bagni
PURPOSE: This study aims to evaluate the prognostic role of the decrease in total lesion glycolysis (TLG) assessed by fluorine-18-fluorodeoxyglucose (F-FDG) PET-computed tomography (CT) 1 month after yttrium-90-radioembolization (Y-RE) in patients affected by hepatocellular carcinoma (HCC) with portal vein tumour thrombosis (PVTT). PATIENTS AND METHODS: Twenty-one patients with histologically proven poorly differentiated HCC and evidence of PVTT at the enhanced multislice CT underwent Y-RE...
June 12, 2018: Nuclear Medicine Communications
https://www.readbyqxmd.com/read/29900922/a-systematic-analysis-on-possibility-of-water-fluoridation-causing-hypothyroidism
#11
REVIEW
Nallan C S K Chaitanya, P Karunakar, Neeharika Satya Jyothi Allam, M Hima Priya, B Alekhya, Shaguftha Nauseen
Background: Community water fluoridation is widely used worldwide and its role in preventive dental health care is well established. However, there is sufficient evidence of the ill effects of excessive fluoride content in water, causing skeletal and dental fluorosis. Alongside, there was also extraskeletal and dental manifestations of excessive fluorides reported. They include the effect on thyroid function, but the literature regarding this is sparse. Aim: The present systematic review aims to analyze the data from controlled studies about the effect of fluoride on thyroid function...
May 2018: Indian Journal of Dental Research: Official Publication of Indian Society for Dental Research
https://www.readbyqxmd.com/read/29900460/oxidation-of-%C3%AE-trifluoromethyl-and-non-fluorinated-alcohols-via-the-merger-of-oxoammonium-cations-and-photoredox-catalysis
#12
Vincent A Pistritto, Joshua M Paolillo, Kathryn A Bisset, Nicholas E Leadbeater
We present an alcohol oxidation strategy to access α-trifluoromethyl ketones (TFMKs) merging catalytic oxoammonium cation oxidation with visible-light photoredox catalysis. This work uses 4-acetamido-(2,2,6,6-tetramethyl-piperidin-1-yl)oxyl as an organic oxidant capable of generating TFMKs in good yields. The methodology serves as an improvement over previous reports of an analogous oxidation strategy requiring superstoichiometric quantities of oxidant. Both primary and secondary non-fluorinated alcohols can also be oxidised in good yields...
June 14, 2018: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/29899963/hydrogen-gas-generation-using-a-metal-free-fluorinated-porphyrin
#13
Yanyu Wu, Nancy Rodríguez-López, Dino Villagrán
Free-base meso -tetra(pentafluorophenyl)porphyrin, 1 , is electrocatalytically active for hydrogen gas generation in the presence of p -toluenesulfonic acid. The electrochemical potential of hydrogen evolution (-1.31 V vs. Fc/Fc+ in THF) is comparable to those of metal containing electrocatalysts such as metallated porphyrins or other metallated macrocycles. Combining experimental observations and DFT computations, we propose the most favorable hydrogen generation mechanism to be a (1) reduction, (2) protonation, (3) reduction, (4) protonation (E-P-E-P) pathway...
May 28, 2018: Chemical Science
https://www.readbyqxmd.com/read/29897571/antagonistic-effects-of-different-selenium-sources-on-growth-inhibition-oxidative-damage-and-apoptosis-induced-by-fluorine-in-broilers
#14
Y X Wang, X Xiao, X A Zhan
Fluorosis can induce oxidative stress through leading to reactive oxygen species (ROS) generation. Selenium (Se) can eliminate ROS by direct and indirect manners. In this study, therefore, we investigated the possible protective effects of sodium selenite (SS) and selenomethionine (Se-Met) on fluorine (F)-induced oxidative stress in broilers. A total of 720 1-day-old Lingnan Yellow broilers were allotted to 4 groups (6 replicates of 30 birds each group) and fed with basal diet (control group), 800 mg/kg F (high F group), 800 mg/kg F+0...
June 11, 2018: Poultry Science
https://www.readbyqxmd.com/read/29896486/characterization-of-polymer-polymer-type-charge-transfer-ct-blend-membranes-for-fuel-cell-application
#15
Shiyan Feng, Shoichi Kondo, Takahiro Kaseyama, Taichi Nakazawa, Takamasa Kikuchi, Roman Selyanchyn, Shigenori Fujikawa, Liana Christiani, Kazunari Sasaki, Masamichi Nishihara
The data presented in this article are related to polymer-polymer type charge-transfer blend membranes for fuel cell application. The visible spectra of the charge-transfer (CT) blend membranes indicated formation of CT complex in the blend membranes, and behavior of CT complex formation by polymers was clarified by Job plot of the visible spectra. The effect of fluorine for membrane property and fuel cell performance of CT blend membranes were evaluated by 19 F NMR and overvoltage analysis, respectively.
June 2018: Data in Brief
https://www.readbyqxmd.com/read/29895890/opioid-receptor-signaling-analgesic-and-side-effects-induced-by-a-computationally-designed-ph-dependent-agonist
#16
Viola Spahn, Giovanna Del Vecchio, Antonio Rodriguez-Gaztelumendi, Julia Temp, Dominika Labuz, Michael Kloner, Marco Reidelbach, Halina Machelska, Marcus Weber, Christoph Stein
Novel pain killers without adverse effects are urgently needed. Opioids induce central and intestinal side effects such as respiratory depression, sedation, addiction, and constipation. We have recently shown that a newly designed agonist with a reduced acid dissociation constant (pKa ) abolished pain by selectively activating peripheral μ-opioid receptors (MOR) in inflamed (acidic) tissues without eliciting side effects. Here, we extended this concept in that pKa reduction to 7.22 was achieved by placing a fluorine atom at the ethylidene bridge in the parental molecule fentanyl...
June 12, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29894188/catalyzed-and-promoted-aliphatic-fluorination
#17
Desta Doro Bume, Stefan Andrew Harry, Thomas Lectka, Cody Ross Pitts
In last six years, the direct functionalization of aliphatic C-H (and C-C) bonds through user-friendly, radical-based fluorination reactions has emerged as an exciting research area in fluorine chemistry. Considering the historical narratives about the challenges of developing practical radical fluorination in organic frameworks, notable advancements in controlling both reactivity and selectivity have been achieved during this time. As one of the participants in the field, herein, we a provide brief account of research efforts in our laboratory from the initial discovery of radical monofluorination on unactivated C-H bonds in 2012 to more useful strategies to install fluorine on biologically relevant molecules through directed fluorination methods...
June 12, 2018: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29894173/modulating-the-nucleophile-of-a-glycoside-hydrolase-through-site-specific-incorporation-of-fluoroglutamic-acids
#18
Miriam P Koetzler, Kyle Robinson, Hong-Ming Chen, Mark Okon, Lawrence P McIntosh, Stephen G Withers
Understanding the detailed mechanisms of enzyme-catalyzed hydrolysis of the glycosidic bond is fundamentally important, not only to the design of tailored cost-efficient, stable and specific catalysts, but also to the development of specific glycoside hydro-lase inhibitors as therapeutics. Retaining glycosidases employ two key carboxylic acid residues, typically glutamic acids, in a double-displacement mechanism involving a covalent glycosyl-enzyme intermediate. One Glu functions as a nucleophile while the other acts as a general acid/base...
June 12, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29894155/informing-molecular-design-by-stereoelectronic-theory-the-fluorine-gauche-effect-in-catalysis
#19
Marialuisa Aufiero, Ryan Gilmour
The axioms of stereoelectronic theory constitute an atlas to navigate the contours of molecular space. All too rarely lauded, the advent and development of stereoelectronic theory has been one of organic chemistry's greatest triumphs. Inevitably, however, in the absence of a comprehensive treatise, many of the field's pioneers do not receive the veneration that they merit. Rather their legacies are the stereoelectronic pillars that persist in teaching and research. This ubiquity continues to afford practitioners of organic chemistry with an abundance of opportunities for creative endeavor in reaction design, in conceiving novel activation modes, in preorganizing intermediates, or in stabilizing productive transition states and products...
June 12, 2018: Accounts of Chemical Research
https://www.readbyqxmd.com/read/29893752/the-prognostic-and-diagnostic-value-of-18f-fdg-pet-ct-for-assessment-of-symptomatic-osteoarthritis
#20
Brian J Nguyen, Ashley Burt, Randall L Baldassare, Edward Smitaman, Maud Morshedi, Steven Kao, Eric Y Chang, Sebastian Obrzut
OBJECTIVE: The objective of this study was to assess the clinical significance of increased fluorine-18-fluorodeoxyglucose (F-FDG) uptake on PET/CT in joints for evaluation of symptomatic osteoarthritis (OA) and prediction of progression. PATIENTS AND METHODS: In this prospective study, shoulder, hip, and knee joints were imaged in 65 patients undergoing routine F-FDG PET/CT imaging. Patients completed the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaire to assess joint pain, stiffness, and physical function...
July 2018: Nuclear Medicine Communications
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