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Daniel J Van Hoomissen, Shubham Vyas
Devising effective degradation technologies for perfluoroalkyl substances (PFASs) is an active area of research, where the molecular mechanisms involving both oxidative and reductive pathways are still elusive. One commonly neglected pathway in PFASs degradation is fluorine atom migration in perfluoroalkyl radicals, which was largely assumed to be implausible because of the high C-F bond strength. Using density functional theory calculations, it was demonstrated that 1,2-F atom migrations are thermodynamically favored when the fluorine atom migrated from less branched carbon center to a more branched carbon center...
October 17, 2017: Journal of Physical Chemistry. A
Aaron T Johnson, T Gannon Parker, Sara M Dickens, Jana K Pfeiffer, Allen G Oliver, Donald Wall, Nathalie A Wall, Martha R Finck, Kevin P Carney
Production of certified reference materials in support of domestic nuclear forensics programs require volatile precursors for introduction into electromagnetic isotopic separation instruments. β-Diketone chelates of tetravalent actinides are known for their high volatility, but previously developed synthetic approaches require starting material (NpCl4) that is prohibitively difficult and hazardous to prepare. An alternative strategy was developed here that uses controlled potential electrolysis to reduce neptunium to the tetravalent state in submolar concentrations of hydrochloric acid...
October 17, 2017: Inorganic Chemistry
Junping Zhang, Jianjun Liao, Fan Yang, Ming Xu, Shiwei Lin
Three non-metallic elements, sulfur, fluorine, and iodine, were used to dope the ultrathin two-dimensional TiO₂ nanosheets, which would regulate their electroanalytical properties toward heavy metal ions. Among these doped materials, fluorine-doped TiO₂ nanosheets shows the highest electrochemical sensitivity and a superior detection limit toward Pb(II) when the doping concentration is 10%. When compared with the bare TiO₂ nanosheets, the sensitivity increased by 102%, and the detection limit decreased by 36...
October 14, 2017: Nanomaterials
Hala Abou Assi, Roberto El-Khoury, Carlos González, Masad J Damha
Human telomeres and promoter regions of genes fulfill a significant role in cellular aging and cancer. These regions comprise of guanine and cytosine-rich repeats, which under certain conditions can fold into G-quadruplex (G4) and i-motif structures, respectively. Herein, we use UV, circular dichroism and NMR spectroscopy to study several human telomeric sequences and demonstrate that G4/i-motif-duplex interconversion kinetics are slowed down dramatically by 2'-β-fluorination and the presence of G4/i-motif-duplex junctions...
September 28, 2017: Nucleic Acids Research
Shuangshuang Zhang, Olivier Oms, Long Hao, Rongji Liu, Meng Wang, Yaqin Zhang, Hong-Yan He, Anne Dolbecq, Jerome Marrot, Bineta Keita, Linjie Zhi, Pierre Mialane, Bin Li, Guangjin Zhang
A series of carbonaceous-supported precious metal-free polyoxometalate (POM)-based composites which can be easily synthesized on a large scale has been shown to act as efficient cathode materials for the oxygen reduction reaction (ORR) in neutral or basic media via a four-electron mechanism with high durability. Moreover, exploiting the versatility of the considered system, its activity has been optimized by the judicious choice of the 3d metals incorporated in the {(PW9)2M7} (M = Co, Ni) POM core, the POM counter-ions and the support (thermalized triazine-based frameworks (TTFs), fluorine-doped TTF (TTF-F), reduced graphene oxide or carbon Vulcan XC-72...
October 16, 2017: ACS Applied Materials & Interfaces
Francisco de Santiago, Alejandro Trejo, Alvaro Miranda, Eliel Carvajal, Luis Antonio Pérez, Miguel Cruz-Irisson
In this work, we address the effects of molecular doping on the electronic properties of fluorinated and chlorinated silicon nanowires (SiNWs), in comparison with those corresponding to hydrogen-passivated SiNWs. Adsorption of n-type dopant molecules on hydrogenated and halogenated SiNWs and their chemisorption energies, formation energies, and electronic band gap are studied by using density functional theory calculations. The results show that there are considerable charge transfers and strong covalent interactions between the dopant molecules and the SiNWs...
October 16, 2017: Journal of Molecular Modeling
Neil Burford, Riccardo Suter, Christopher Frazee, Robert McDonald, Michael Ferguson
We present new cationic coordination complexes of antimony with the 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (DippBIAN) ligand system. The fluoroantimony complexes [SbF(DippBIAN)][OTf]2 and [SbF2(DippBIAN)][OTf] have been successfully isolated and characterized. The fluorine substituent in the Lewis acidic complex [SbF(DippBIAN)][OTf]2 can be selectively replaced without degradation of the Sb-DippBIAN interaction to give the first dicationic azido and cyano derivatives, [Sb(CN)(DippBIAN)][OTf]2 and [Sb(N3)(DippBIAN)][OTf]2, which have been isolated and structurally characterized...
October 15, 2017: Chemistry: a European Journal
Deepa Singh, Rajender Kumar, Ashim Das, Subhash C Varma, Bhagwant R Mittal
Malignant peripheral nerve sheath tumors (MPNSTs) are rare neuroectodermal tumors resulting from the malignant transformation of benign plexiform neurofibromas. The sporadic form of these tumors is rare than familial variants (seen in neurofibromatosis Type 1) and making the diagnosis difficult. We are presenting a case of 40--year-old female with the complaint of progressive swelling of lower limb with initial suspicion of lymphedema and underwent lymphoscintigraphy, magnetic resonance imaging, and finally fluorine-18-2-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography scans were done to rule out mitotic etiology and extent of the disease...
October 2017: World Journal of Nuclear Medicine
Nandigam Santosh Kumar, Yogesh Shejul, Ramesh Asopa, Sandip Basu
The purpose of this study was to assess the role of fluoro-2-deoxy-D-glucose-positron emission tomography/computed tomography (FDG-PET/CT) in the evaluation of treatment response evaluation to disease-modifying antirheumatic drug (DMARD) therapy in patients of rheumatoid arthritis (RA). A total of ten patients with proven diagnosis of RA as per the 2010 American College of Rheumatology/European League against Rheumatism (EULAR) criteria were prospectively evaluated. All patients underwent clinical and biochemical evaluation and a baseline FDG-PET/CT with assessment of maximum standardized uptake value and metabolic volumetric product (MVP) values...
October 2017: World Journal of Nuclear Medicine
Yuri Bedjanian
The kinetics and products of the reactions of F atoms with Br2 and ClNO have been studied in a flow reactor coupled with an electron impact ionization mass spectrometer at nearly 2 Torr total pressure of helium and over a wide temperature range, T = 295 - 950 K. The rate constant of the reaction F + ClNO  products (1) was determined under pseudo-first order conditions, monitoring the kinetics of F-atom consumption in excess of ClNO. The measured temperature independent rate constant, k1 = (1.29 ± 0.13)×10-10 cm3molecule-1s-1 (T = 299-950 K), was found to be in excellent agreement with the only previous low temperature study which allowed to recommend the value of k1 in an extended temperature range, (228 - 950) K...
October 14, 2017: Journal of Physical Chemistry. A
Xue Liu, Zengyao Wang, Chengji Zhao, Wenhuan Bu, Yurong Zhang, Hui Na
A fluorinated acrylate monomer (4-TF-PQEA) without BPA (bisphenol-A) structure was synthesized and mixed with triethylene glycol dimethacrylate (TEGDMA) to used as dental resin system in order to achieve lower water sorption and reduce human exposure to BPA derivatives. Double bond conversion (DC) was measured using Fourier transform infrared spectroscopy (FTIR). Water sorption (WS), water solution (WL) and depth of cure (DOC) were evaluated according to ISO 4049:2009. Water contact angle (CA) was measured using contact angle analyzer...
September 21, 2017: Journal of the Mechanical Behavior of Biomedical Materials
Gyudong Kim, Ji-Seong Yoon, Dnyandev B Jarhad, Young Sup Shin, Mahesh S Majik, Varughese A Mulamoottil, Xiyan Hou, Shuhao Qu, Jiyong Park, Mu-Hyun Baik, Lak Shin Jeong
(-)-6'-β-Fluoro-aristeromycin (2), a potent inhibitor of S-adenosylhomocysteine (AdoHcy) hydrolase, has been synthesized via stereoselective electrophilic fluorination followed by a purine base build-up approach. Interestingly, purine base condensation using a cyclic sulfate resulted in a synthesis of (+)-5'-β-fluoro-isoaristeromycin (2a). Computational analysis indicates that the fluorine atom controlled the regioselectivity of the purine base substitution.
October 13, 2017: Organic Letters
Cristina García-Ruiz, Jack L-Y Chen, Christopher Sandford, Kathryn Feeney, Paula Lorenzo, Guillaume Berionni, Herbert Mayr, Varinder K Aggarwal
Allylboronic esters react readily with carbonyls and imines (π-electrophiles), but are unreactive towards a range of other electrophiles. By addition of an aryl organolithium, the corresponding allylboronate complexes display enhanced nucleophilicity, enabling addition to a range of electrophiles (tropylium, benzodithiolylium, activated pyridines, Eschenmoser's salt, Togni's reagent, Selectfluor, DIAD, MeSX) in high regio- and stereocontrol. This protocol provides access to key new functionalities, including quaternary stereogenic centers bearing moieties such as fluorine and the trifluoromethyl group...
October 13, 2017: Journal of the American Chemical Society
Chuanxiao Xiao, Changlei Wang, Weijun Ke, Brian Gorman, Jichun Ye, Chun-Sheng Jiang, Yanfa Yan, Mowafak Al-Jassim
Electron-selective layers (ESLs) and hole-selective layers (HSLs) are critical in high-efficiency organic-inorganic lead halide perovskite (PS) solar cells for charge-carrier transport, separation, and collection. We developed a procedure to assess the quality of the ESL/PS junction by measuring potential distribution on cross-section of SnO2-based perovskite solar cells using Kelvin probe force microscopy. Using the potential profiling, we compared three types of cells made of different ESLs but otherwise having identical device structure: 1) cells with PS deposited directly on bare fluorine-doped SnO2 (FTO)-coated glass; 2) cells with an intrinsic SnO2 thin layer on the top of FTO as an effective ESL; and 3) cells with the SnO2 ESL and adding a self-assembled monolayer (SAM) of fullerene...
October 13, 2017: ACS Applied Materials & Interfaces
Z Ahmed, A Siiskonen, M Virkki, A Priimagi
We present a series of visible-light-absorbing azobenzene photoswitches with cis-lifetimes ranging from one second to three days. We combine ortho-fluorination to control the cis-lifetimes, and ortho-amination to boost the visible-light absorption. The synthesis is accomplished by selectively replacing one or more ortho-fluorines with amines in the ortho-fluoroazobenzene precursors.
October 13, 2017: Chemical Communications: Chem Comm
David J Donnelly, Ralph Adam Smith, Paul Morin, Dasa Lipovsek, Jochem Gokemeijer, Daniel Cohen, Virginie Lafont, Tritin Tran, Erin Lee Cole, Martin Wright, Joonyoung Kim, Adrienne Pena, Daniel Kukral, Douglas D Dischino, Patrick Chow, Jinping Gan, Olufemi Adelakun, Xi-Tao Wang, Kai Cao, David Lueng, Samuel Bonacorsi, Wendy Hayes
The programmed death protein (PD-1) and its ligand (PD-L1) play critical roles in a checkpoint pathway cancer cells exploit to evade the immune system. A same-day PET imaging agent for measuring PD-L1 status in primary and metastatic lesions could be important for optimizing drug therapy. Herein, we have evaluated the tumor targeting of an anti-PD-L1 Adnectin after (18)F-fluorine labeling. Methods: An anti-PD-L1 Adnectin was labeled with (18)F in two steps. This synthesis featured fluorination of a novel prosthetic group, followed by a copper-free click conjugation to a modified Adnectin to generate (18)F-BMS-986192...
October 12, 2017: Journal of Nuclear Medicine: Official Publication, Society of Nuclear Medicine
He Chen, Zhonglin Liu, Ying Lv, Xinqiang Tan, Haigen Shen, Hai-Zhu Yu, Chaozhong Li
Direct fluorination of tertiary alkyl bromides and iodides with Selectfluor reagent is described. The halogen-exchange fluorination proceeds efficiently in acetonitrile at room temperature under metal-free conditions and exhibits a wide range of functional group compatibility. Furthermore, the reactions are highly selective in that alkyl chlorides and primary and secondary alkyl bromides remain intact. A radical mechanism is proposed for this selective fluorination.
October 11, 2017: Angewandte Chemie
Stefan Wagner, Matteo Accorsi, Jörg Rademann
α,α-Difluoro-benzyl phosphonates are currently the most popular class of phosphotyrosine mimetics. Structurally derived from the natural substrate phosphotyrosine, they constitute classical bioisosteres and have enabled the development of potent inhibitors of protein tyrosine phosphatases (PTP) and phosphotyrosine recognition sites such as SH2 domains. Being dianions bearing two negative charges, phosphonates, however, do not permeate membranes and thus are often inactive in cells and have not been a successful starting point toward therapeutics, yet...
October 11, 2017: Chemistry: a European Journal
Johannes Ermert
The increasing importance of the positron emission tomography (PET) in clinical diagnosis led to the development of a multitude of radiotracers labelled with positron emitting radionuclides of group 15 (pnicogens) and 16 (chalcogens) of the periodic table of elements. The positron emitters of the endogenous occurring elements nitrogen, phosphorus, oxygen and sulphur are characterized by very short half-lives compared to the most commonly used PET-radionuclides carbon-11 or fluorine-18. Therefore, the potential of their synthesis and possible applications in PET is challenging and limited...
October 11, 2017: Journal of Labelled Compounds & Radiopharmaceuticals
Philip Gerretsen, Jun Ku Chung, Parita Shah, Eric Plitman, Yusuke Iwata, Fernando Caravaggio, Shinichiro Nakajima, Bruce G Pollock, Ariel Graff-Guerrero
OBJECTIVE: Anosognosia, or impaired illness awareness, is a common feature of Alzheimer's disease (AD) and less so of mild cognitive impairment (MCI). Importantly, anosognosia negatively influences clinical outcomes for patients and their caregivers and may predict the conversion from MCI to AD. This study aimed to examine (1) the relationship between brain glucose metabolism as measured by fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) and anosognosia in patients with MCI and AD and (2) the predictive utility of anosognosia in patients with MCI for later conversion to AD, even when controlling for other factors, including gender, education, apolipoprotein E ε4 carrier status, dementia severity, and cognitive dysfunction...
October 10, 2017: Journal of Clinical Psychiatry
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