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https://www.readbyqxmd.com/read/29136304/reversible-polymerization-of-adamantane-type-p4n10-10-anions-to-honeycomb-type-p2n5-5-layers-under-high-pressure
#1
Eva-Maria Bertschler, Robin Niklaus, Wolfgang Schnick
The high-pressure polymorph Li5P2N5 of Li10P4N10 (= "2 Li5P2N5") was synthesized by high-pressure/high-temperature reaction of LiPN2 and Li7PN4 or beta-Li10P4N10 at 9 GPa, using the Li3N self-flux method in a Walker-type multianvil assembly. Li5P2N5 is the first lithium nitridophosphate with a layered structure and is made up of corner sharing PN4 tetrahedra forming a corrugated honeycomb-type layer of linked sechser-rings in chair conformation. The arrangement of the P atoms is analogous to that of black phosphorus...
November 14, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29073228/using-a-whole-body-31p-birdcage-transmit-coil-and-16-element-receive-array-for-human-cardiac-metabolic-imaging-at-7t
#2
Ladislav Valkovič, Iulius Dragonu, Salam Almujayyaz, Alex Batzakis, Liam A J Young, Lucian A B Purvis, William T Clarke, Tobias Wichmann, Titus Lanz, Stefan Neubauer, Matthew D Robson, Dennis W J Klomp, Christopher T Rodgers
PURPOSE: Cardiac phosphorus magnetic resonance spectroscopy (31P-MRS) provides unique insight into the mechanisms of heart failure. Yet, clinical applications have been hindered by the restricted sensitivity of the surface radiofrequency-coils normally used. These permit the analysis of spectra only from the interventricular septum, or large volumes of myocardium, which may not be meaningful in focal disease. Löring et al. recently presented a prototype whole-body (52 cm diameter) transmit/receive birdcage coil for 31P at 7T...
2017: PloS One
https://www.readbyqxmd.com/read/29068097/antimicrobial-peptide-structure-from-model-membranes-to-live-cells
#3
Marc-Antoine Sani, Frances Separovic
The rise in antibiotic resistance has led to a renewed interest in antimicrobial peptides (AMPs) that target membranes. The mode of action of AMPs involves the disruption of the lipid bilayer and leads to growth inhibition and death of the bacteria. However, details at the molecular level of how these peptides kill bacteria and the reasons for the observed differences in selectivity remain unclear. Structural information is crucial for defining the molecular mechanism by which these peptides recognize, self-assemble and interact with a particular lipid membrane...
October 25, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29065692/diffusion-ordered-nuclear-magnetic-resonance-spectroscopy-dosy-nmr-a-novel-tool-for-identification-of-phosphorus-compounds-in-soil-extracts
#4
Liming Wang, Wulf Amelung, Sabine Willbold
Liquid-state, one-dimension 31P nuclear magnetic resonance spectrometry (NMR) has greatly advanced our understanding of the composition of organic phosphorous in the environment. However, the correct assignment of signals is complicated by overlapping and shifting signals in different types of soils. We applied therefore for the first time diffusion-ordered nuclear magnetic spectroscopy (DOSY) to soil extracts, allowing us to separate phosphorus components in the second domain based on their translational diffusion coefficient...
October 25, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/29048734/imidazolium-based-ionic-liquids-as-efficient-reagents-for-lignin-c-o-bond-cleavage
#5
Marina Thierry, Amel Majira, Bruce Pégot, Laurent Cézard, Flavien Bourdreux, Gilles Clément, François Perreau, Stéphanie Boutet-Mercey, Patrick Diter, Giang Vo-Thanh, Catherine Lapierre, Paul-Henri Ducrot, Emmanuel Magnier, Stephanie Baumberger, Betty Cottyn
Lignin chemical demethylation in ionic liquids was investigated using pure lignin-model monomers and dimer together with dioxan isolated lignins from poplar, miscanthus and maize. Different methylimidazolium ionic liquids (ILs) were compared, according to two different heating processes, microwave irradiation and conventional heating in sealed tube. The conversion yield and influence of the treatments on lignin structure were assessed by 31P NMR, size exclusion chromatography and thioacidolysis. The acidic IL [HMIM][Br] was shown to be an effective combination solvent/reagent for the demethylation and even depolymerisation of lignin...
October 19, 2017: ChemSusChem
https://www.readbyqxmd.com/read/29030245/effect-of-phosphatidylcholine-bilayer-thickness-and-molecular-order-on-the-binding-of-the-antimicrobial-peptide-maculatin-1-1
#6
Tzong-Hsien Lee, Marc-Antoine Sani, Sarah Overall, Frances Separovic, Marie-Isabel Aguilar
Antimicrobial peptides (AMPs) interact directly with bacterial membrane lipids. Thus, changes in the lipid composition of bacterial membranes can have profound effects on the activity of AMPs. In order to understand the effect of bilayer thickness and molecular order on the activity of AMPs, the interaction of maculatin 1.1 (Mac1.1) with phosphatidylcholine (PC) model membranes composed of different monounsaturated acyl chain lengths between 14 and 22 carbons was characterised by dual polarisation interferometry (DPI) and 31P and 1H solid-state NMR techniques...
October 10, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/29023101/biosynthesis-of-nucleoside-diphosphoramidates-in-campylobacter-jejuni
#7
Zane W Taylor, Haley A Brown, Hazel M Holden, Frank M Raushel
Campylobacter jejuni is a pathogenic Gram-negative bacterium and a leading cause of food-borne gastroenteritis. C. jejuni produces a capsular polysaccharide (CPS) that contains a unique O-methyl phosphoramidate modification (MeOPN). Recently, the first step in the biosynthetic pathway for the assembly of the MeOPN modification to the CPS was elucidated. It was shown that the enzyme Cj1418 catalyzes the phosphorylation of the amide nitrogen of l-glutamine to form l-glutamine phosphate. In this investigation, the metabolic fate of l-glutamine phosphate was determined...
October 24, 2017: Biochemistry
https://www.readbyqxmd.com/read/28994190/analysis-of-molecular-orientation-in-organic-semiconducting-thin-films-using-static-dynamic-nuclear-polarization-enhanced-solid-state-nmr-spectroscopy
#8
Katsuaki Suzuki, Shosei Kubo, Fabien Aussenac, Frank Engelke, Tatsuya Fukushima, Hironori Kaji
Molecular orientation in amorphous organic semiconducting thin-film devices is an important issue affecting device performance. However, to date it has not been possible to analyze the "distribution" of the orientations. Although solid-state NMR (ssNMR) spectroscopy can provide information on the "distribution" of molecular orientations, the technique is limited because of the small amount of sample in the device and the low sensitivity of ssNMR. Here, we report the first application of dynamic nuclear polarization enhanced ssNMR (DNP-ssNMR) spectroscopy for the orientational analysis of amorphous phenyldi(pyren-1-yl)phosphine oxide (POPy2 )...
October 9, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28981459/high-resolution-nmr-spectroscopy-as-a-structural-and-analytical-tool-for-unsaturated-lipids-in-solution
#9
REVIEW
Eleni Alexandri, Raheel Ahmed, Hina Siddiqui, Muhammad I Choudhary, Constantinos G Tsiafoulis, Ioannis P Gerothanassis
Mono- and polyunsaturated lipids are widely distributed in Nature, and are structurally and functionally a diverse class of molecules with a variety of physicochemical, biological, medicinal and nutritional properties. High resolution NMR spectroscopic techniques including 1H-, 13C- and 31P-NMR have been successfully employed as a structural and analytical tool for unsaturated lipids. The objective of this review article is to provide: (i) an overview of the critical 1H-, 13C- and 31P-NMR parameters for structural and analytical investigations; (ii) an overview of various 1D and 2D NMR techniques that have been used for resonance assignments; (iii) selected analytical and structural studies with emphasis in the identification of major and minor unsaturated fatty acids in complex lipid extracts without the need for the isolation of the individual components; (iv) selected investigations of oxidation products of lipids; (v) applications in the emerging field of lipidomics; (vi) studies of protein-lipid interactions at a molecular level; (vii) practical considerations and (viii) an overview of future developments in the field...
October 5, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28960495/near-ir-absorbing-organometallic-diruthenium-complex-intermediates-evidence-for-bridging-anthrasemiquinone-formation-and-against-mixed-valency
#10
Thangavel Sathiya Kamatchi, Sudipta Mondal, Thomas Scherer, Martina Bubrin, Karupannan Natarajan, Wolfgang Kaim
The new redox-active complexes [RuH(CO)(EPh3)2(-Q2-)RuH(CO)(EPh3)2], E = P (1) and E = As (2) with the bis-chelate bridging ligand Q2- = 1,4-dioxido-9,10-anthraquinone were prepared and characterised. The related compound [RuCl(CO)(PPh3)2(-Qx2-)RuCl(CO)(PPh3)2] (4) with E = P and Qx2- = 5,8-dioxido-1,4-naphthoquinone 4 revealed trans-positioned PPh¬3 groups. The electrogenerated one-electron oxidised states 1+ and 2+ were examined using spectroelectrochemical techniques (EPR, IR and UV-vis-NIR). In situ EPR studies gave spectra with 31P or 75As hyperfine splitting of about 16 Gauss, small 99,101Ru coupling and small g anisotropy in the frozen solution state...
September 28, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28957374/synthesis-and-characterization-of-modified-%C3%AE%C2%BA-carrageenan-for-enhanced-proton-conductivity-as-polymer-electrolyte-membrane
#11
Joy Wei Yi Liew, Kee Shyuan Loh, Azizan Ahmad, Kean Long Lim, Wan Ramli Wan Daud
Polymer electrolyte membranes based on the natural polymer κ-carrageenan were modified and characterized for application in electrochemical devices. In general, pure κ-carrageenan membranes show a low ionic conductivity. New membranes were developed by chemically modifying κ-carrageenan via phosphorylation to produce O-methylene phosphonic κ-carrageenan (OMPC), which showed enhanced membrane conductivity. The membranes were prepared by a solution casting method. The chemical structure of OMPC samples were characterized using Fourier transform infrared spectroscopy (FTIR), 1H nuclear magnetic resonance (1H NMR) spectroscopy and 31P nuclear magnetic resonance (31P NMR) spectroscopy...
2017: PloS One
https://www.readbyqxmd.com/read/28949967/preoperative-indication-for-systemic-therapy-extended-to-patients-with-early-stage-breast-cancer-using-multiparametric-7-tesla-breast-mri
#12
A M T Schmitz, W B Veldhuis, M B E Menke-Pluijmers, W J M van der Kemp, T A van der Velden, M A Viergever, W P T M Mali, M C J M Kock, P J Westenend, D W J Klomp, K G A Gilhuijs
PURPOSE: To establish a preoperative decision model for accurate indication of systemic therapy in early-stage breast cancer using multiparametric MRI at 7-tesla field strength. MATERIALS AND METHODS: Patients eligible for breast-conserving therapy were consecutively included. Patients underwent conventional diagnostic workup and one preoperative multiparametric 7-tesla breast MRI. The postoperative (gold standard) indication for systemic therapy was established from resected tumor and lymph-node tissue, based on 10-year risk-estimates of breast cancer mortality and relapse using Adjuvant! Online...
2017: PloS One
https://www.readbyqxmd.com/read/28926703/effect-of-nonionic-surfactants-on-dispersion-and-polar-interactions-in-the-adsorption-of-cellulases-onto-lignin
#13
Feng Jiang, Chen Qian, Alan R Esker, Maren Roman
Residual lignin in pretreated biomass impedes enzymatic hydrolysis. Nonionic surfactants are known to enhance the enzymatic hydrolysis of lignocellulosic biomass but their mechanisms of action are incompletely understood. This study investigates the effect of a nonionic surfactant, Tween 80, on the adsorption of cellulases onto model lignin substrates. Lignin substrates were prepared by spin coating of flat substrates with three different types of lignin: organosolv lignin, kraft lignin, and milled wood lignin...
October 6, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28872861/entropic-anomaly-observed-in-lipid-polymorphisms-induced-by-surfactant-peptide-sp-b-1-25
#14
Nhi Tran, Justin Kurian, Avni Bhatt, Robert McKenna, Joanna R Long
The N-terminal 25 amino-acid residues of pulmonary surfactant protein B (SP-B1-25) induces unusual lipid polymorphisms in a model lipid system, 4:1 DPPC/POPG, mirroring the lipid composition of native pulmonary surfactant. It is widely suggested that SP-B1-25-induced lipid polymorphisms within the alveolar aqueous subphase provide a structural platform for rapid lipid adsorption to the air-water interface. Here, we characterize in detail the phase behavior of DPPC and POPG in hydrated lipid assemblies containing therapeutic levels of SP-B1-25 using (2)H and (31)P solid state NMR spectroscopy...
September 25, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28872843/diffusion-controllable-biomineralization-conducted-in-situ-in-hydrogels-based-on-reversibly-cross-linked-hyperbranched-polyglycidol
#15
Mateusz Gosecki, Slawomir Kazmierski, Monika Gosecka
We present biocompatible hydrogel systems suitable for biomineralization processes based on hyperbranched polyglycidol cross-linked with acrylamide copolymer bearing carbonyl-coordinated boronic acid. At neutral pH, diol functional groups of HbPGL react with boronic acid of polyacrylamide to generate 3D network in water by the formation of boronic ester cross-links. The dynamic associative/dissociative characteristics of the cross-links makes the network reversible. The presented hydrogels display self-healing properties and are injectable, facilitating gap filing of bone tissue...
September 13, 2017: Biomacromolecules
https://www.readbyqxmd.com/read/28871490/a-comparison-of-the-responsiveness-of-eq-5d-5l-and-the-qolie-31p-and-mapping-of-qolie-31p-to-eq-5d-5l-in-epilepsy
#16
Ben F M Wijnen, Iris Mosweu, Marian H J M Majoie, Leone Ridsdale, Reina J A de Kinderen, Silvia M A A Evers, Paul McCrone
OBJECTIVE: To investigate the responsiveness of and correlation between the EQ-5D-5L and the QOLIE-31P in patients with epilepsy, and develop a mapping function to predict EQ-5D-5L values based on the QOLIE-31P for use in economic evaluations. METHODS: The dataset was derived from two clinical trials, the ZMILE study in the Netherlands and the SMILE study in the UK. In both studies, patients' quality of life using the EQ-5D-5L and QOLIE-31P was measured at baseline and 12 months follow-up...
September 4, 2017: European Journal of Health Economics: HEPAC: Health Economics in Prevention and Care
https://www.readbyqxmd.com/read/28862853/guanidinium-promoted-cleavage-of-phosphoric-diesters-kinetic-investigations-and-calculations-provide-indications-on-the-operating-mechanism
#17
Riccardo Salvio, Alessandro Casnati
The catalytic activity of the guanidinium units toward the cleavage of phosphoric diesters is deeply investigated both with kinetic experiments and DFT calculations. The first part of the investigation aims to determine how the structure of the substrate (phenyl or alkyl esters) is able to influence the guanidinium-catalyzed hydrolysis changing the mechanism from ANDN to AN+DN. In the cleavage of the DNA model bis(4-nitrophenyl)phospate (BNPP), experimental kinetic data highlight the operation of a guanidine-guanidinium catalytic dyad that can act both intermolecularly and intramolecularly on different molecular scaffolds exhibiting notable values of effective molarity...
September 19, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28862293/bismuth-iii-complexes-with-bis-dimethylphenyl-dithiophosphates-synthesis-characterization-and-crystal-structure-of-3-5-ch3-2c6h3o-2ps2-3bi
#18
Ruchi Khajuria, Sandeep Kumar, Mandeep Kour, Atiya Syed, Geeta Hundal, K Sushil Pandey
This work presents four complexes with general formula [(ArO)2PS23Bi] (1-4), where Ar = 2,4-(CH3)2C6H3, 2,5-(CH3)2C6H3, 3,4-(CH3)2C6H3 and 3,5-(CH3)2C6H3, respectively. Reaction of [(ArO)2PS2Na] with Bi(NO3)3 · 5H2O in toluene in 3:1 molar stoichiometry afforded the complexes [(ArO)2PS23Bi]. These newly synthesized complexes have been characterized by elemental analysis, FT-IR and multinuclear NMR (1H, 13C and 31P) NMR. The crystal structure of [(3,5-CH3)2C6H3O2PS2]3Bi (4) has been determined by X-ray crystallography...
September 2017: Acta Chimica Slovenica
https://www.readbyqxmd.com/read/28853180/di-hydroperoxy-alkane-adducts-of-phosphine-oxides-safe-solid-stoichiometric-and-soluble-oxidizing-agents
#19
Janet Bluemel, Shin Hye Ahn, Nattamai Bhuvanesh
The di(hydroperoxy)alkane adducts of phosphine oxides Ph3PO*(HOO)2CMe2 (1), Cy3PO*(HOO)2CMe2 (2), Ph3PO*(HOO)2CMeEt (3), Cy3PO*(HOO)2CMeEt (4), Cy3PO*(HOO)2CEt2 (5), Cy3PO*(HOO)2C(CH2)5 (6), and Cy3PO*(HOO)2CMePh (7), (Ph2P(O)CH2CH2P(O)Ph2)*((HOO)2CEt2)2 (8), and Ph2P(O)CH2P(O)Ph2*(HOO)2CMe2 (9), are synthesized and fully characterized by 1H, 13C, and 31P NMR and IR spectroscopy. Single crystal X-ray structures are reported for 3-9. Different one-pot synthetic pathways, starting from R3P, R3PO, R3PO*H2O, and R3PO*H2O2 are explored and discussed and a mechanism for the formation of the di(hydroperoxy)alkane adducts of phosphine oxides is suggested...
August 29, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28837326/bidentate-phosphine-assisted-synthesis-of-an-all-alkynyl-protected-ag74-nanocluster
#20
Mei Qu, Huan Li, Lin-Hua Xie, Shuai-Ting Yan, Jian-Rong Li, Jun-Hao Wang, Cai-Yun Wei, Yu-Wei Wu, Xian-Ming Zhang
Determining the total structure of metal nanoparticles is vital to understand their properties. In this work, the first all-alkynyl-protected Ag nanocluster, Ag74(C≡CPh)44, was synthesized and structurally characterized by single crystal diffraction. Ag atoms are arranged in a Ag4@Ag22@Ag48 three shell structure and all 44 phenylethynyl ligands coordinated with Ag in a μ3 mode. In spite of being absent in nanocluster, (31)P NMR study reveals that bidentate phosphine first reacts with Ag(I) to form a dinuclear complex, from which Ag atoms are then released to phenylethynyl ligands...
August 28, 2017: Journal of the American Chemical Society
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