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L Jonas L Häller, Elena Mas-Marzá, Mateusz K Cybulski, Rajashekharayya A Sanguramath, Stuart A Macgregor, Mary F Mahon, Christophe Raynaud, Christopher A Russell, Michael K Whittlesey
Relativistic density functional theory calculations, both with and without the effects of spin-orbit coupling, have been employed to model hydride NMR chemical shifts for a series of [Ru(NHC)4(L)H](0/+) species (NHC = N-heterocyclic carbene; L = vacant, H2, N2, CO, MeCN, O2, P4, SO2, H(-), F(-) and Cl(-)), as well as selected phosphine analogues [Ru(R2PCH2CH2PR2)2(L)H](+) (R = (i)Pr, Cy; L = vacant, O2). Inclusion of spin-orbit coupling provides good agreement with the experimental data. For the NHC systems large variations in hydride chemical shift are shown to arise from the paramagnetic term, with high net shielding (L = vacant, Cl(-), F(-)) being reinforced by the contribution from spin-orbit coupling...
February 28, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
M Benedetti, F De Castro, F P Fanizzi
An inverse linear relationship between (73)Ge, (119)Sn and (207)Pb NMR chemical shifts and the overall sum of ionic radii of coordinated halido ligands has been discovered in tetrahedral [MXnY4-n] (M = Ge, Sn, Pb; 1 ≤ n ≤ 4; X, Y = Cl, Br, I) coordination compounds. This finding is consistent with a previously reported correlation found in octahedral, pentacoordinate and square planar platinum complexes. The effect of the coordinated halido ligands acting on the metal as shielding conducting rings is therefore confirmed also by (73)Ge, (119)Sn and (207)Pb NMR spectroscopy...
February 9, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Marcus Zuber, Michael Laaß, Elias Hamann, Sophie Kretschmer, Norbert Hauschke, Thomas van de Kamp, Tilo Baumbach, Thomas Koenig
Non-destructive imaging techniques can be extremely useful tools for the investigation and the assessment of palaeontological objects, as mechanical preparation of rare and valuable fossils is precluded in most cases. However, palaeontologists are often faced with the problem of choosing a method among a wide range of available techniques. In this case study, we employ x-ray computed tomography (CT) and computed laminography (CL) to study the first fossil xiphosuran from the Muschelkalk (Middle Triassic) of the Netherlands...
January 27, 2017: Scientific Reports
Michelle Lewis, Casey L Peiris, Nora Shields
QUESTION: Do long-term (> 3 months) home or community-based exercise programs improve function, reduce falls and prevent hospital readmissions in older people with cognitive impairment? DESIGN: Systematic review and meta-analysis of randomised, controlled trials. Electronic databases (CINAHL, PubMed, Medline, Embase, AMED) were searched from the earliest date possible until March 2016. PARTICIPANTS: Older adults (≥ 65 years) with cognitive impairment living in the community...
January 2017: Journal of Physiotherapy
Marcin Broniatowski, Monika Urbaś
Anionic phospholipids cardiolipins (CL) and phosphatidylglycerols (PG) dominate in the biomembranes of the majority of soil bacteria. CL to PG ratio differs between the species and is also dependent on the external conditions. CL/PG ratio is different in polluted than in unspoiled soils and it was hypothesized that it is connected with the activity of the membranelytic enzymes from the phospholipase A2 class (PLA2) as it was proved that persistent soil pollutants can activate PLA2. In our studies we applied the Langmuir monolayer technique and Brewster angle microscopy to elucidate the mechanism of the interactions of PLA2 with the model membranes formed by anionic phospholipids...
February 2017: Biochimica et Biophysica Acta
Ibon Alkorta, Jose Elguero, Janet E Del Bene
MP2/aug'-cc-pVTZ calculations have been carried out to investigate boron as an electron-pair donor in halogen-bonded complexes H(CO)2B:ClX and H(N2)2B:ClX, for X = F, Cl, OH, NC, CN, CCH, CH3, and H.Equilibrium halogen-bonded complexes with boron the electron-pair donor have been found on all of the potential surfaces except for H(CO)2B:ClCH3 and H(N2)2B:ClF.The majority of these complexes are stabilized by traditional halogen bonds, except for H(CO)2B:ClF, H(CO)2B:ClCl, H(N2)2B:ClCl, and H(N2)2B:ClOH which are stabilized by chlorine-shared halogen bonds...
July 14, 2016: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Roman Savka, Marvin Bergmann, Yuki Kanai, Sabine Foro, Herbert Plenio
Based on 1-amino-4-hydroxy-triptycene, new saturated and unsaturated triptycene-NHC (N-heterocyclic carbene) ligands were synthesized from glyoxal-derived diimines. The respective carbenes were converted into metal complexes [(NHC)MX] (M=Cu, Ag, Au; X=Cl, Br) and [(NHC)MCl(cod)] (M=Rh, Ir; cod=1,5-cyclooctadiene) in good yields. The new azolium salts and metal complexes suffer from limited solubility in common organic solvents. Consequently, the introduction of solubilizing groups (such as 2-ethylhexyl or 1-hexyl by O-alkylation) is essential to render the complexes soluble...
July 4, 2016: Chemistry: a European Journal
Shahbaz Ahmed, Derek Brown, Saad B S Ahmed, Muhammad B Kakakhel, Wazir Muhammad, Amjad Hussain
A revised translating bed total body irradiation (TBI) technique is developed for shielding organs at risk (lungs) to tolerance dose limits, and optimizing dose distribution in three dimensions (3D) using an asymmetrically-adjusted, dynamic multileaf collimator. We present a dosimetric comparison of this technique with a previously developed symmetric MLC-based TBI technique. An anthropomor-phic RANDO phantom is CT scanned with 3 mm slice thickness. Radiological depths (RD) are calculated on individual CT slices along the divergent ray lines...
March 8, 2016: Journal of Applied Clinical Medical Physics
Arman Mashayekhi, Murat Hasanreisoglu, Carol L Shields, Jerry A Shields
PURPOSE: To determine the efficacy and safety of external beam radiation for treatment of choroidal lymphoma (CL). DESIGN: Retrospective case series. PARTICIPANTS: Twenty-five eyes of 24 patients with CL treated with external beam radiation. METHOD: Review of medical records. MAIN OUTCOME MEASURES: Tumor control, visual acuity, and radiation complications. RESULTS: The mean age of the patients was 62 years (median, 65; range, 32-89 years)...
October 2016: Retina
Amy M Dennett, Casey L Peiris, Nora Shields, Luke A Prendergast, Nicholas F Taylor
QUESTION: Is there a dose-response effect of exercise on inflammation, fatigue and activity in cancer survivors? DESIGN: Systematic review with meta-regression analysis of randomised trials. PARTICIPANTS: Adults diagnosed with cancer, regardless of specific diagnosis or treatment. INTERVENTION: Exercise interventions including aerobic and/or resistance as a key component. OUTCOME MEASURES: The primary outcome measures were markers of inflammation (including C-reactive protein and interleukins) and various measures of fatigue...
April 2016: Journal of Physiotherapy
Irina V Mirzaeva, Dmitry A Mainichev, Svetlana G Kozlova
(103)Rh NMR parameters and the bonding structure of three complexes of [Cp*RhX2]2, where X = Cl, Br, or I, have been studied with the help of natural bond orbitals (NBOs) and natural localized molecular orbitals (NLMOs). The complexes of [Cp*RhX2]2, where X = Cl, Br, or I, have similar bonding structures, with the major difference being in the degree of covalency of the Rh-X bonds. The decomposition of (103)Rh NMR shielding into diamagnetic, paramagnetic, and spin-orbit terms shows that normal halogen dependence (NHD) of the (103)Rh NMR shift is defined mostly by the paramagnetic term, with the spin-orbit term being significantly smaller...
March 24, 2016: Journal of Physical Chemistry. A
Dhilon S Patel, Suyong Re, Emilia L Wu, Yifei Qi, Phillip E Klebba, Göran Widmalm, Min Sun Yeom, Yuji Sugita, Wonpil Im
The asymmetric outer membrane of Gram-negative bacteria is formed of the inner leaflet with phospholipids and the outer leaflet with lipopolysaccharides (LPS). Outer membrane protein F (OmpF) is a trimeric porin responsible for the passive transport of small molecules across the outer membrane of Escherichia coli. Here, we report the impact of different levels of heterogeneity in LPS environments on the structure and dynamics of OmpF using all-atom molecular dynamics simulations. The simulations provide insight into the flexibility and dynamics of LPS components that are highly dependent on local environments, with lipid A being the most rigid and O-antigen being the most flexible...
February 23, 2016: Biophysical Journal
Kentaro Ifuku, Takumi Noguchi
Photosystem II (PSII), which catalyzes photosynthetic water oxidation, is composed of more than 20 subunits, including membrane-intrinsic and -extrinsic proteins. The PSII extrinsic proteins shield the catalytic Mn4CaO5 cluster from the outside bulk solution and enhance binding of inorganic cofactors, such as Ca(2+) and Cl(-), in the oxygen-evolving center (OEC) of PSII. Among PSII extrinsic proteins, PsbO is commonly found in all oxygenic organisms, while PsbP and PsbQ are specific to higher plants and green algae, and PsbU, PsbV, CyanoQ, and CyanoP exist in cyanobacteria...
2016: Frontiers in Plant Science
B Suchéras-Marx, F Giraud, A Simionovici, I Daniel, R Tucoulou
Heterococcoliths are micron-scale calcite platelets produced by coccolithophores. They have been the most abundant and continuous fossil record over the last 215 million years (Myr), offering great potential for geochemical studies, although the heterococcolith fossil record remains underutilised in this domain. We have mapped heterococcoliths' composition using X-ray fluorescence (XRF) with a 100-nm resolution beam to decipher element distributions in heterococcoliths and to investigate the potential development of geochemical proxies for palaeoceanography...
July 2016: Geobiology
Xiuyi Lin, Xi Shen, Xinying Sun, Xu Liu, Ying Wu, Zhenyu Wang, Jang-Kyo Kim
This paper reports simultaneous modification of graphene oxide (GO) papers by functionalization with MgCl2. The Mg(2+) ions enhance both the interlayer cross-links and lateral bridging between the edges of adjacent GO sheets by forming Mg-O bonds. The improved load transfer between the GO sheets gives rise to a maximum of 200 and 400% increases in Young's modulus and tensile strength of GO papers. The intercalation of chlorine between the GO layers alters the properties of GO papers in two ways by forming ionic Cl(-) and covalent C-Cl bonds...
January 27, 2016: ACS Applied Materials & Interfaces
Sarosh P Batlivala, Dennise Magill, Marc A Felice, Virginia Jones, Yoav Dori, Matthew J Gillespie, Jonathan J Rome, Andrew C Glatz
Cardiac catheterisation personnel are exposed to occupational radiation and its health risks. Little data exist regarding the efficacy of radiation-protective equipment from congenital catheterisation laboratories (CLs). The authors retrospectively reviewed data in which CL operators wore a radiation dosemeter during catheterizations on patients of >20 kg. A leaded under-table skirt was present in all cases. Three additional radiation-protective devices were utilised at operator discretion: a top extension to the under-table skirt, a ceiling-mounted shield and a disposable patient drape...
December 2016: Radiation Protection Dosimetry
Taye B Demissie, Michał Jaszuński, Stanislav Komorovsky, Michal Repisky, Kenneth Ruud
We present nuclear spin-rotation constants, absolute nuclear magnetic resonance (NMR) shielding constants, and shielding spans of all the nuclei in (175)LuX and (197)AuX (X = (19)F, (35)Cl, (79)Br, (127)I), calculated using coupled-cluster singles-and-doubles with a perturbative triples (CCSD(T)) correction theory, four-component relativistic density functional theory (relativistic DFT), and non-relativistic DFT. The total nuclear spin-rotation constants determined by adding the relativistic corrections obtained from DFT calculations to the CCSD(T) values are in general in agreement with available experimental data, indicating that the computational approach followed in this study allows us to predict reliable results for the unknown spin-rotation constants in these molecules...
October 28, 2015: Journal of Chemical Physics
Alejandro F Maldonado, Juan I Melo, Gustavo A Aucar
Accurate calculations of nuclear magnetic shieldings of group-11 metal halides, σ(M; MX) (M = Cu, Ag, Au; X = H, F, Cl, Br, I), were performed with relativistic and nonrelativistic theoretical schemes in order to learn more about the importance of the involved electronic mechanisms that underlie such shieldings. We applied state of the art schemes: polarization propagators at a random phase level of approach (PP-RPA); spin-free Hamiltonian (SF); linear response elimination of small component (LRESC) and density functional theory (DFT) with two different functionals: B3LYP and PBE0...
October 14, 2015: Physical Chemistry Chemical Physics: PCCP
Renan V Viesser, Lucas C Ducati, Jochen Autschbach, Cláudio F Tormena
In this study, stereoelectronic interactions were considered to explain the experimental difference in the magnitude of the known heavy-atom effect on the (13)C NMR chemical shifts in cis- and trans-1,2-dihaloethene isomers (halo = F, Cl, Br or I). The experimental values were compared to the calculated values with various DFT functionals using both the nonrelativistic approach (NR) and the relativistic approximations SR-ZORA (SR) and SO-ZORA (SO). NBO and NLMO contributions to the (13)C NMR shielding tensors were determined to assess which stereoelectronic interactions have a more important effect on the shielding tensor in each principal axis system (PAS) coordinate...
July 15, 2015: Physical Chemistry Chemical Physics: PCCP
Jinghuan Chen, Jikun Xu, Kun Wang, Xueren Qian, Runcang Sun
In this study, graphite powder (GP) was introduced into the conductive cellulose/polypyrrole (PPy) composite films to increase their conductivity and thermal stability. The GP was dispersed in ionic liquid 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) before the dissolution of cellulose, and the cellulose/GP/PPy films were prepared by in situ chemical polymerization of PPy nanoparticles on the film surface. The structural characteristics and properties of the composite films were investigated in detail. The GP flakes, which were embedded in the cellulose matrix, increased the thickness and decreased the density of the films, leading to the decrement of mechanical properties...
July 22, 2015: ACS Applied Materials & Interfaces
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