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Sebastian Molitor, Kai-Stephan Feichtner, Viktoria H Gessner
While Li/Cl carbenoids are versatile reagents in organic synthesis, the controlled handling of the extremely reactive and labile M/F carbenoids remains a challenge. We now show that even these compounds can be stabilized and isolated in solid state as well as in solution. Particularly the sodium and potassium com¬pounds exhibit a remarkable stability, thus allowing the first isolation of a room temperature stable fluorine carbenoid. Spectro¬scopic as well as DFT studies confirm the pronounced carbenoid character, showing M-F-C interactions with elongated C-F bonds...
December 1, 2016: Chemistry: a European Journal
Jerome Graton, Guillaume Compain, François Besseau, Elena Bogdan, Joe Watts, Lewis Mtashobya, Zhong Wang, Alex Weymouth-Wilson, Nicolas Galland, Jean-Yves Le Questel, Bruno Linclau
Rational modulations of molecular interactions are of significant importance in compound properties optimization. We have previously shown that fluorination of conformationally rigid cyclohexanols leads to attenuation of their hydrogen-bond (H-bond) donating capacity (pKAHY) when OH***F intramolecular hydrogen-bond (IMHB) interactions occur, as opposed to an increase in pKAHY due to the fluorine electronegativity. This work has now been extended to a wider range of aliphatic β-fluorohydrins with increasing degrees of conformational flexibility...
December 1, 2016: Chemistry: a European Journal
Christoph Alexander Bauer, Andreas Hansen, Stefan Grimme
The fractional occupation number weighted density (FOD) analysis is explored as a general theoretical diagnostic for complicated electronic structures. Its main feature is to provide robustly and fast the information where 'hot' (strongly correlated and chemically active) electrons are localized in a molecule. We demonstrate its usage in four different prototypical applications: (i) As a new and fast measure for the biradical character of polycyclic aromatic hydrocarbons, (ii) for the selection of active orbital spaces in multiconfigurational or complete active space self consistent field (MCSCF/CASSCF) treatments, (iii) as a possibility to consistently describe molecular energy landscapes in regions with varying biradical character as exemplified by partial double bond torsions, and (iv) as a powerful visualization method for static electron correlation effects in large biomolecules in connection with an efficient semi-empirical tight-binding molecular orbital scheme...
December 1, 2016: Chemistry: a European Journal
Avelino Corma, Antonio Leyva, Miguel Angel Rivero
The Pt-catalysed hydrosilylation of alkynes is the procedure of choice to obtain vinylsilanes, and this is claimed to be the most relevant application of Pt in organic synthesis. More than half a century after its discovery, only -vinylsilanes (anti-Markovnikov addition) are obtained with simple Pt catalysts, while -vinylsilanes (Markovnikov addition) remain elusive compounds. Here we report that Pt3 clusters, in part-per-million (ppm) amounts, catalyse the Markovnikov hydrosilylation of terminal alkynes to give a wide variety of -vinylsilanes in reasonable isolated yields and with turnover frequencies that can reach up to one million per hour...
December 1, 2016: Chemistry: a European Journal
Valery Fedorovich Sidorkin, Elena Fedorovna Belogolova, Yu Wang, Viatcheslav Jouikov, Evgeniya Pavlovna Doronina
Using 18 silatranes XSi(OCH2CH2)3N (1) as an example, the potentials of electrochemical oxidation E0 of the hypervalent compounds of Si were calculated for the first time at the ab initio and DFT levels. The experimental peak potentials Ep show an excellent agreement (MAE = 0.03) with the MP2//B3PW91 calculated E0 (C-PCM). Radical cations of 1 reveal a "stretch isomerism" of the NSi dative bond. Localization of the spin density (SD) on the substituent X and the short (s) coordination contact Si…N (dSiN < 2...
December 1, 2016: Chemistry: a European Journal
Bao Zha, Meiqiu Dong, Xinrui Miao, Shan Peng, Yican Wu, Kai Miao, Yi Hu, Wenli Deng
Herein, the photophysical properties of two π-conjugated thienophenanthrene derivatives (6,9- and 5,10-DBTD) are reported. Their self-assembled monolayers in aliphatic hydrocarbon solvents under different concentrations were investigated by scanning tunneling microscopy on a graphite surface. The STM results revealed that the self-assembled structures of the two geometrical isomers exhibited absolutely different behaviors. At the aliphatic solvent/graphite interface, 6,9-DBTD produced almost a single stable coassembled linear structure, except for that with n-tridecane as the solvent...
December 1, 2016: Nanoscale
Wu-Chao Zhai, Tie-Zhu Qiao, Dong-Jin Cai, Wen-Jie Wang, Jing-Dong Chen, Zhi-Hui Chen, Shao-Ding Liu
Third-harmonic generation with metallic or dielectric nanoparticles often suffer from, respectively, small modal volumes and weak near-field enhancements. This study propose and demonstrate that a metallic/dielectric hybrid nanostructure composed of a silver double rectangular nanoring and a silicon square nanoplate can be used to overcome these obstacles for enhanced third-harmonic generation. It is shown that the nonradiative anapole mode of the Si plate can be used as a localized source to excite the dark subradiant octupole mode of the Ag ring, and the mode hybridization leads to the formation of an antibonding and a bonding subradiant collective mode, thereby forming anticrossing double Fano resonances...
November 28, 2016: Optics Express
Huifang Zhang, Chun Li, Caihong Zhang, Xueqian Zhang, Jianqiang Gu, Biaobing Jin, Jiaguang Han, Weili Zhang
Plasmonic dimers that made from two subwavelength particles have drawn much attention in the recent years, which are quite promising in local field enhancement, sensing, high frequency conductance probing and electron tunneling. In this work, we experimentally investigate the mode transition effect of different plasmonic resonances in double-ring dimers when introducing conductive junction at the dimer gap in the terahertz regime. Without the junction, the dimers support a single dipolar bonding dimer plasmonic (BDP) mode...
November 28, 2016: Optics Express
Swati Bhople, Swapnil Gaikwad, Swapna Deshmukh, Shital Bonde, Aniket Gade, Sanjib Sen, Anna Brezinska, Hanna Dahm, Mahendra Rai
The authors report Myxobacteria virescens (M. virescens) mediated synthesis of silver nanoparticles (AgNPs) and its efficacy against Staphylococcus aureus (ATCC-33591), Salmonella typhi (ATCC-51812), Escherichia coli (E. coli) (ATCC-14948), Klebsiella pneumoniae (MTCC-4030) and Pseudomonas aeruginosa (MTCC-4673). The organism exhibiting resistance to various antibiotics showed remarkable sensitivity, when used in combination of antibiotics and AgNPs. Antimicrobial property of AgNPs is playing a significant role in medicine and food storage...
December 2016: IET Nanobiotechnology
Jef Hens, Wim Jennes, Luc Kestens
Natural killer (NK) cells specialize in killing virally infected- or tumor cells and are part of the innate immune system. The activational state of NK cells is determined by the balance of incoming activating and inhibitory signals mediated by receptor-ligand binding with the target cell. These receptor-ligand bonds mainly consist of the killer immunoglobulin-like receptors (KIR), which are expressed at the cell surface of NK cells, and their ligands: the highly variable human leukocyte antigen -class I molecules (HLA)...
March 18, 2016: AIDS Research and Therapy
Brynmor Lloyd-Evans, Gary R Bond, Torleif Ruud, Ada Ivanecka, Richard Gray, David Osborn, Fiona Nolan, Claire Henderson, Oliver Mason, Nicky Goater, Kathleen Kelly, Gareth Ambler, Nicola Morant, Steve Onyett, Danielle Lamb, Sarah Fahmy, Ellie Brown, Beth Paterson, Angela Sweeney, David Hindle, Kate Fullarton, Johanna Frerichs, Sonia Johnson
BACKGROUND: Crisis Resolution Teams (CRTs) provide short-term intensive home treatment to people experiencing mental health crisis. Trial evidence suggests CRTs can be effective at reducing hospital admissions and increasing satisfaction with acute care. When scaled up to national level however, CRT implementation and outcomes have been variable. We aimed to develop and test a fidelity scale to assess adherence to a model of best practice for CRTs, based on best available evidence. METHODS: A concept mapping process was used to develop a CRT fidelity scale...
December 1, 2016: BMC Psychiatry
(no author information available yet)
This rule updates and makes revisions to the End-Stage Renal Disease (ESRD) Prospective Payment System (PPS) for calendar year 2017. It also finalizes policies for coverage and payment for renal dialysis services furnished by an ESRD facility to individuals with acute kidney injury. This rule also sets forth requirements for the ESRD Quality Incentive Program, including the inclusion of new quality measures beginning with payment year (PY) 2020 and provides updates to programmatic policies for the PY 2018 and PY 2019 ESRD QIP...
November 4, 2016: Federal Register
X Wang, M Ackermann, E Tolba, M Neufurth, F Wurm, Q Feng, S Wang, H C Schröder, W E Müller
Here we show that inorganic polyphosphate (polyP), a polyanionic metabolic regulator consisting of multiple phosphate residues linked by energy-rich phosphoanhydride bonds, is present in the synovial fluid. In a biomimetic approach, to enhance cartilage synthesis and regeneration, we prepared amorphous polyP microparticles with Mg2+ as counterions. The particles were characterised by X-ray diffraction (XRD), energy-dispersive X-ray (EDX) and Fourier transformed infrared spectroscopic (FTIR) analyses. Similar particles were obtained after addition of Mg2+ ions to a solution containing hyaluronic acid, as a major component of the synovial fluid, and soluble Na-polyP...
November 29, 2016: European Cells & Materials
Estela Arcos, Ximena Sánchez, Christine Bailey, Luis González, Antonia Vollrath, Luz Angélica Muñoz
BACKGROUND: Social capital is an economical idea that refers to connections between individuals and entities that can be economically valuable. AIM: To establish the relationship of social capital as a health care asset, with sociodemographic variables of older women attending public health care services. MATERIAL AND METHODS: Chen’s Personal Social Capital scale was applied to 113 women aged between 64 and 80 years during 2014. Cronbach’s alpha of the instrument was calculated...
August 2016: Revista Médica de Chile
Anamika Mukhopadhyay, Lilit Jacob, Sugumar Venkataramani
DFT (U)B3LYP/cc-pVTZ and (U)M06-2X/cc-pVTZ and multireference CASSCF/cc-pVTZ level of theories have been used to investigate the electronic structure of isomeric dehydrooxazole (1b-d, 3 isomers), dehydrothiazole (2b-d, 3 isomers) and dehydroimidazole (3a-d, 4 isomers) radicals. The ground state electronic structure of each radical isomer has been confirmed by predicting their doublet excited state structure and calculating the adiabatic energy difference. The stability order of the individual isomeric radicals has been estimated through the comparison of absolute energies...
December 1, 2016: Physical Chemistry Chemical Physics: PCCP
Afik Shachar, Nitzan Mayorkas, Hanan Sachs, Ilana Bar
Fluorination is considered as a possible means for alteration of conformational landscapes in molecules. The effect of fluorine substitution was studied here by measuring the vibronic and vibrational spectra of gas phase 2-(4-fluoro-phenyl)-ethylamine (4-FPEA) by resonant two-photon ionization (R2PI) and by ionization-loss stimulated Raman spectroscopy (ILSRS). The measurement of survey ILSR spectra of 4-FPEA in the amino group region allowed to associate the bands in the R2PI spectrum to origin and vibronic transitions of the ground (S0) to the excited (S1) electronic states of three different conformers...
December 1, 2016: Physical Chemistry Chemical Physics: PCCP
Prithwish K Nandi, Niall J English, Zdenek Futera, Antonio Benedetto
Water is fundamental to the biochemistry of enzymes. It is well known that without a minimum amount of water, enzymes are not biologically active. Bare minimal solvation for biological function corresponds to about a single layer of water covering enzymes' surfaces. Many contradictory studies on protein-hydration-water-coupled dynamics have been published in recent decades. Following prevailing wisdom, a dynamical crossover in hydration water (at around 220 K for hydrated lysozymes) can trigger larger-amplitude motions of the protein, activating, in turn, biological functions...
December 1, 2016: Physical Chemistry Chemical Physics: PCCP
Jonathan F D Liljeblad, István Furó, Eric C Tyrode
In order to establish the potential correlation between the macroscopic ice adhesion and the molecular properties of the premolten layer (PML), the adhesion strength between ice and hydrophilic silica has been measured as a function of temperature. In addition, temperature-dependent molecular properties have been determined using techniques that are sensitive to different aspects of the PML, specifically total internal reflection (TIR) Raman, vibrational sum frequency (VSFS) and NMR spectroscopies. The ice shear adhesion strength was observed to increase linearly with decreasing temperature until -25 °C, where a plateau marked the adhesive strength having reached the cohesive strength of ice...
December 1, 2016: Physical Chemistry Chemical Physics: PCCP
A S Schröder, E Parsa, K Iwan, F R Traube, M Wallner, S Serdjukow, T Carell
A deeper investigation of the chemistry that occurs on the newly discovered epigenetic DNA bases 5-hydroxymethyl-(hmdC), 5-formyl-(fdC), and 5-carboxy-deoxycytidine (cadC) requires chemical tool compounds, which are able to dissect the different potential reaction pathways in cells. Here we report that the 2'-(R)-fluorinated derivatives F-hmdC, F-fdC, and F-cadC, which are resistant to removal by base excision repair, are good substrates for DNA polymerases and TET enzymes. This result shows that the fluorinated compounds are ideal tool substances to investigate potential C-C-bond cleaving reactions in the context of active demethylation...
December 1, 2016: Chemical Communications: Chem Comm
Jinian Shu, Yao Zou, Ce Xu, Zhen Li, Wanqi Sun, Bo Yang, Haixu Zhang, Peng Zhang, Pengkun Ma
Doping has been used to enhance the ionization efficiency of analytes in atmospheric pressure photoionization, which is based on charge exchange. Compounds with excellent ionization efficiencies are usually chosen as dopants. In this paper, we report a new phenomenon observed in low-pressure photoionization: Protonation enhancement by dichloromethane (CH2Cl2) doping. CH2Cl2 is not a common dopant due to its high ionization energy (11.33 eV). The low-pressure photoionization source was built using a krypton VUV lamp that emits photons with energies of 10...
December 1, 2016: Scientific Reports
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