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PubMed Journals Articles About "NAVIN FLUORINE" RSS

08:14 EST 19th November 2018 | BioPortfolio

NAVIN FLUORINE PubMed articles on BioPortfolio. Our PubMed references draw on over 21 million records from the medical literature. Here you can see the latest NAVIN FLUORINE articles that have been published worldwide.

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Showing "NAVIN FLUORINE" PubMed Articles 1–25 of 162

Transition Metal-Mediated and -Catalyzed C-F Bond Activation via Fluorine Elimination.

Activation of carbon-fluorine (C-F) bonds is an important topic in synthetic organic chemistry recently. Among the methods for C-F bond cleavage, metal mediated and catalyzed β- or α-fluorine elimination proceeds under mild conditions compared with oxidative addition of C-F bond. The β- or α-fluorine elimination is initiated from organometallic intermediates having fluorine substituents on carbon atoms β or α to metal centers, respectively. Transformations via these elimination processes (C-F bond cle...


Diastereo- and Enantioselective Synthesis of Fluorine Motifs with Two Contiguous Stereogenic Centers.

The synthesis of chiral fluorine-containing motifs, especially chiral fluorine molecules with two contiguous stereogenic centers have been gaining current interest in research due to the limited number of methods for their preparation. Herein we report an atom economical and highly stereoselective synthesis of chiral fluorine molecule with two contiguous stereogenic centers via azabicyclo iridium-oxazoline-phosphine-catalyzed hydrogenation of readily available vinyl-fluorides. Various aromatic, aliphatic an...

Exploring atypical fluorine-hydrogen bonds and their effects on nucleoside conformations.

The ability of fluorine to serve as a hydrogen-bond acceptor has been debated for many years. Short fluorine-hydrogen contacts are thought to play a key role in stabilizing some complex supramolecular systems. To directly probe the existence of fluorine-hydrogen bonds, we have carried out NMR experiments and computational modeling studies in a series of C2'-fluorinated nucleosides. Specifically, quantum mechanics-molecular mechanics (QM/MM) analysis and [19F-1H]-HMBC NMR experiments provided direct evidence...


Fluorine walk: The impact of fluorine in quinolone amides on their activity against African sleeping sickness.

Human African Trypanosomiasis, also known as African sleeping sickness, is caused by the parasitic protozoa of the genus Trypanosoma. If there is no pharmacological intervention, the parasites can cross the blood-brain barrier (BBB), inevitably leading to death of the patients. Previous investigation identified the quinolone amide GHQ168 as a promising lead compound having a nanomolar activity against T. b. brucei. Here, the role of a fluorine substitution at different positions was investigated in regard ...

MiR-132, miR-204 and BDNF-TrkB signaling pathway may be involved in spatial learning and memory impairment of the offspring rats caused by fluorine and aluminum exposure during the embryonic stage and into adulthood.

Fluorine and aluminium are nervous system poisons, but it remains unclear whether combined fluorine and aluminium exposure damages spatial learning and memory and, if so, by what mechanism. This study showed that exposure to fluorine and aluminium, either alone or combined, during the embryonic stage and into adulthood caused spatial learning and memory impairment in offspring rats; its mechanism may be associated with increases in miR-132 and miR-204 expression and downregulation of the BDNF-TrkB pathway i...

Morphology and electronic structure modulation induced by fluorine doping in nickel-based heterostructures for robust bifunctional electrocatalysis.

Fabrication of advanced electrocatalysts with high activity and durability is urgently needed to achieve energy conversion and pollution treatment at the same time. Herein, we highlight a fluorine-doped nickel-based heterostructure, in which fluorine doping displays a dual effect in Ni(OH)2 nanosheets/Ni3S2 heteronanorods. On the one hand, fluorine doping can facilitate the formation of Ni(OH)2 nanosheets/Ni3S2 heteronanorods through one-step in situ growth on nickel foams. The unique heterostructure enable...

Radical Carbofluorination of Unactivated Alkenes with Fluoride Ion.

The copper-assisted radical carbofluorination of unactivated alkenes with fluoride ion is described. With [Cu(L3)F2]H2O (L3 = 4,4'-di(methoxycarbonyl)-2,2'-bipyridine) as the fluorine source and [Ag(DMPhen)(MeCN)]BF4 (DMPhen = 2,9-dimethyl-1,10-phenanthroline) as the chloride scavenger, the reaction of unactivated alkenes with CCl4 in acetonitrile provided the corresponding carbofluorination products in satisfactory yields. The protocol exhibited a wide functional group compatibility and broad substrate sco...

Improving metabolic stability of fluorine-18 labeled verapamil analogs.

Fluorine-18 labeled positron emission tomography (PET) tracers were developed to obtain more insight into the function of P-glycoprotein (P-gp) in relation to various conditions. They allow research in facilities without a cyclotron as they can be transported with a half-life of 110 min. As the metabolic stability of previously reported tracers [F]1 and [F]2 was poor, the purpose of this study was to improve this stability using deuterium substitution, creating verapamil analogs [F]1-d, [F]2-d, [F]3-d and...

The efficacy of fluorine-18-choline PET/CT in comparison with 99mTc-MIBI SPECT/CT in the localization of a hyperfunctioning parathyroid gland in primary hyperparathyroidism.

The aim of this study was to determine the role of fluorine-18-choline (F-FCH) PET/CT in comparison with technetium-99m-methoxyisobutylisonitrile (Tc-MIBI) single-photon emission computed tomography/computed tomography (SPECT/CT) in primary hyperparathyroidism and to investigate whether maximum standardized uptake value (SUVmax) may be indicative of disease severity.

Thermal Atomic Layer Etching of Silica and Alumina Thin Films Using Trimethylaluminum with Hydrogen Fluoride or Fluoroform.

Thermal atomic layer etching (ALE) is an emerging technique that involves the sequential removal of monolayers of a film by alternating self-limiting reactions, some of which generate volatile products. Although traditional ALE processes rely on the use of plasma, several thermal ALE processes have recently been developed using hydrogen fluoride (HF) with precursors such as trimethylaluminum (TMA) or tin acetylacetonate. While HF is currently the most effective reagent for ALE, its potential hazards and cor...

Optimal timing of fluorine-18-fluoromisonidazole positron emission tomography/computed tomography for assessment of tumor hypoxia in patients with head and neck squamous cell carcinoma.

The aim of this study was to identify the optimal timing of fluorine-18-fluoromisonidazole (F-MISO) PET/CT imaging to assess hypoxia in patients with head and neck squamous cell carcinoma.

Rational design of low cost and high energy lithium batteries through tailored fluorine-free electrolyte and nanostructured sulfur/carbon composite.

We report a new lithium/sulfur cell concept based on an optimized fluorine-free catholyte solution and a high loading nanostructured carbon/sulfur composite cathode. The Li2S8 present in the electrolyte ensures both buffering against active material dissolution and Li+ conduction. The high sulfur loading is obtained by confining elemental sulfur (~80%) in the mesopores of a highly ordered CMK3 carbon. With this concept we demonstrate stabilization of high energy density and excellent cycling performance ove...

Photoelectrocatalytic degradation of atrazine by boron-fluorine co-doped TiO nanotube arrays.

Atrazine, one of the most widespread herbicides in the world, is considered as an environmental estrogen and has potential carcinogenicity. In this study, atrazine was degraded on boron-fluorine co-doped TiO nanotube arrays (B, F-TiO NTAs), which had similar morphology with the pristine TiO NTAs. The structure and morphology of TiO nanotube samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and UV-visible diffuse reflectance spectroscopy (DRS). It showed that the deco...

Diagnostic value of fluorine-18 deoxyglucose positron emission tomography/computed tomography in deep sternal wound infection.

Deep sternal wound infection (DSWI) is a refractory complication after heart surgery, and debridement is the first-line treatment. The accurate identification of the extent of the infection is the key to successful debridement. The present study assessed the diagnostic accuracy of fluorine-18 deoxyglucose (F-FDG) positron emission tomography/computed tomography (PET/CT) for identifying the infected area of DSWI.

A simple quantitative chiral analysis of amino acid esters by fluorine-19 nuclear magnetic resonance using the modified James-Bull method.

A simple chiral analysis of amino acid esters by fluorine-19 nuclear magnetic resonance ( F NMR) through the modified James-Bull method is described. Thus, amino acid ester acid salt was treated with 5-fluoro-2-formylphenylboronic acid and (S)-BINOL in the presence of triethylamine (TEA) and MS4A for 10 minutes. The reaction mixture was analysed by F NMR directly to afford good quantifications.

Finding the Better Fit: The Microwave Spectrum and Sterically Preferred Structure of Trans-1,2-Difluoroethylene-Hydrogen Chloride.

The rotational spectrum of the gas-phase bimolecular heterodimer formed between trans-1,2-difluoroethylene and hydrogen chloride is obtained using Fourier transform microwave spectroscopy from 5.6 to 20.6 GHz. Analysis of the spectrum provides rotational constants and nuclear quadrupole coupling constants that are used to determine the structure of the complex. The HCl molecule forms a hydrogen bond with one of the two electrostatically equivalent fluorine atoms of the difluoroethylene, and this hydrogen bo...

Relationship of Water Content With Silicon and Fluorine Contents of Silicone-Hydrogel Contact Lens Materials.

The relationship between water (W) content and silicon (Si) content of silicone-hydrogel (SiHy) contact lens materials was inspected using identical methodologies, equipment, and operators for materials composing 16 types of commercially available SiHy contact lenses. Fluorine (F) content was included in the analysis for the three materials also containing a fluoropolymer. One type of lens consisted of a bulk SiHy material coated with thin layers of conventional hydrogel.

Fluorine-containing lupane triterpenoid acid derivatives: Design, synthesis and biological evaluation as potential anti-inflammatory agents.

A series of novel fluorine-containing lupane triterpenoid acid derivatives with fluoroaromatic amide moieties at the C-28 position (1-8) or with 2-(fluoroacyl)cyclopentane-1,3-dione fragments at the C-3 position (9-18) of lupane skeleton was synthesized. A simple synthesis of novel lupane triterpenoid hybrids with 2-(fluoroacyl)-2-cyclopenten-1-one moieties was developed. An interaction of 2-acyl-3-chlorocyclopent-2-en-1-ones, obtained from corresponding cyclic β-triketones, with methyl 3-amino-3-deoxybetu...

AgFeOF: A Fluorine-Rich Perovskite Oxyfluoride.

We synthesized a silver iron oxyfluoride AgFeOF by using a high-pressure reaction. Synchrotron X-ray and neutron diffraction, X-ray absorption, and Fe Mössbauer spectroscopy indicate that AgFeOF crystallizes in the ideal perovskite structure with iron in a trivalent state, although electron microscopy revealed weak super-reflections. A possible partial ordering in the FeOF octahedron is inferred from Mössbauer spectroscopy. The synthesis of the fluorine-rich sample offers an opportunity to study a composi...

One-pot synthesis and biodistribution of fluorine-18 labeled serum albumin for vascular imaging.

Equilibrium single-photon radionuclide imaging methods for assessing cardiac function and the integrity of the vascular system have long been in use for both clinical and research purposes. However, positron-emitting blood pool agents that could provide PET equivalents to these (and other) clinical procedures have not yet been adopted despite technical imaging advantages offered by PET. Our goal was to develop a PET blood pool tracer that not only meets necessary in vivo biological requirements but can be p...

Fluorine-free Water-in-Salt Electrolyte for Green and Low-cost Aqueous Sodium-Ion Batteries.

The highly concentrated "Water-in-Salt" electrolyte (WiSE) containing sodium acetate and potassium acetate demonstrates peculiar performance (specific capacity of 37 mAh g-1 at 5th cycle and average discharge voltage of 0.82 V) in aqueous sodium-ion batteries (SIBs) based on Na2MnFe(CN)6 and NaTi2(PO4)3. The fluorine-free electrolyte offers wide electrochemical stability window and compatibility with Al current collector. The electrolyte, current collector and the electrode materials based on abundant eleme...

Catalyzed and Promoted Aliphatic Fluorination.

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...

Antibacterial ability, cytocompatibility and hemocompatibility of fluorinated graphene.

Graphene halides are promising two-dimensional systems which have interesting physical and chemical properties. In particular, high quality fluorinated graphene offers a great potential in modulating variable properties by regulating its surface microstructure. Moreover, the fluorine introduction and carbon-fluorine bonding characters will enable some interesting biological response. Here, the biological responses to bacteria and cells of fluorinated graphene were studied. Present work revealed that partial...

Self-assembled, Fluorine-rich Porous Organic Polymers: A Class of Mechanically Stiff and Hydrophobic Materials.

Fluorous organic building blocks have been cogently harnessed to develop two self-assembled, hydrophobic and fluorinated porous organic polymers (FPOPs) namely, FPOP-100 and FPOP-101. On comprehensive mechanical analyses of these functionalized triazine network polymers, they mark the introduction of mechanical stiffness among all porous organic network materials; recorded stiffness features analogous to their organic-inorganic hybrid polymer analogues, viz. metal-organic frameworks (MOFs). Further, the stu...

A Chiron approach towards the stereoselective synthesis of polyfluorinated carbohydrates.

The replacement of hydroxyl groups by fluorine atoms on hexopyranose scaffolds may allow access to the discovery of new chemical entities possessing unique physical, chemical and ultimately even biological properties. The prospect of significant effects generated by such multiple and controlled substitutions encouraged us to develop diverse synthetic routes towards the stereoselective synthesis of polyfluorinated hexopyranoses, six of which are unprecedented. Hence, we report the synthesis of heavily fluori...


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