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https://www.readbyqxmd.com/read/28340463/hypoxia-and-hydrogen-sulfide-differentially-affect-normal-and-tumor-derived-vascular-endothelium
#1
Serena Bianco, Daniele Mancardi, Annalisa Merlino, Benedetta Bussolati, Luca Munaron
BACKGROUND: endothelial cells play a key role in vessels formation both under physiological and pathological conditions. Their behavior is influenced by blood components including gasotransmitters (H2S, NO and CO). Tumor cells are subjected to a cyclic shift between pro-oxidative and hypoxic state and, in this scenario, H2S can be both cytoprotective and detrimental depending on its concentration. H2S effects on tumors onset and development is scarcely studied, particularly concerning tumor angiogenesis...
March 18, 2017: Redox Biology
https://www.readbyqxmd.com/read/28339201/high-throughput-in-silico-structure-validation-and-revision-of-halogenated-natural-products-is-enabled-by-parametric-corrections-to-dft-computed-13-c-nmr-chemical-shifts-and-spin-spin-coupling-constants
#2
Andrei G Kutateladze, D Sai Reddy
Halogenated natural products constitute diverse and promising feedstock for molecular pharmaceuticals. However, their solution-structure elucidation by NMR presents several challenges, including the lack of fast methods to compute (13)C chemical shifts for carbons bearing heavy atoms. We show that parametric corrections to DFT-computed chemical shifts in conjunction with rff-computed spin-spin coupling constants allow for fast and reliable screening of a large number of reported halogenated natural products, resulting in expedient structure validation or revision...
March 24, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28338628/revision-of-the-structure-of-acremine-p-from-a-marine-derived-strain-of-acremonium-persicinum
#3
Mary J Garson, Warren Hehre, Gregory K Pierens, Suciati
The previously published structure of the fungal metabolite acremine P is revised by re-evaluation of chemical shift values and NOESY data, and by DFT calculations.
March 24, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28338623/a-study-of-intramolecular-hydrogen-bonding-in-levoglucosan-derivatives
#4
Lucas Quiquempoix, Elena Bogdan, Neil J Wells, Jean-Yves Le Questel, Jérôme Graton, Bruno Linclau
Organofluorine is a weak hydrogen-bond (HB) acceptor. Bernet et al. have demonstrated its capability to perturb OH···O intramolecular hydrogen bonds (IMHBs), using conformationally rigid carbohydrate scaffolds including levoglucosan derivatives. These investigations are supplemented here by experimental and theoretical studies involving six new levoglucosan derivatives, and complement the findings of Bernet et al. However, it is shown that conformational analysis is instrumental in interpreting the experimental data, due to the occurrence of non-intramolecular hydrogen-bonded populations which, although minor, cannot be neglected and appears surprisingly significant...
March 24, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28338062/coexistence-of-superconductivity-and-charge-density-wave-in-the-quasi-one-dimensional-material-hfte3
#5
Saleem J Denholme, Akinori Yukawa, Kohei Tsumura, Masanori Nagao, Ryuji Tamura, Satoshi Watauchi, Isao Tanaka, Hideaki Takayanagi, Nobuaki Miyakawa
We present the first experimental evidence for metallicity, superconductivity (SC) and the co-existence of charge density waves (CDW) in the quasi-one-dimensional material HfTe3. The existence of such phenomena is a typical characteristic of the transition metal chalcogenides however, without the application of hydrostatic pressure/chemical doping, it is rare for a material to exhibit the co-existence of both states. Materials such as HfTe3 can therefore provide us with a unique insight into the relationship between these multiple ordered states...
March 24, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28337848/designing-smart-materials-with-recombinant-proteins
#6
REVIEW
Sydney Hollingshead, Charng-Yu Lin, Julie C Liu
Recombinant protein design allows modular protein domains with different functionalities and responsive behaviors to be easily combined. Inclusion of these protein domains can enable recombinant proteins to have complex responses to their environment (e.g., temperature-triggered aggregation followed by enzyme-mediated cleavage for drug delivery or pH-triggered conformational change and self-assembly leading to structural stabilization by adjacent complementary residues). These "smart" behaviors can be tuned by amino acid identity and sequence, chemical modifications, and addition of other components...
March 24, 2017: Macromolecular Bioscience
https://www.readbyqxmd.com/read/28336532/moag-4-promotes-the-aggregation-of-%C3%AE-synuclein-by-competing-with-self-protective-electrostatic-interactions
#7
Yuichi Yoshimura, Mats A Holmberg, Predrag Kukic, Camilla B Andersen, Alejandro Mata-Cabana, S Fabio Falsone, Michele Vendruscolo, Ellen A A Nollen, Frans A A Mulder
Aberrant protein aggregation underlies a variety of age-related neurodegenerative disorders, including Alzheimer's and Parkinson's diseases. Little is known, however, about the molecular mechanisms that modulate the aggregation process in the cellular environment. Recently, MOAG-4/SERF has been identified as a class of evolutionarily conserved proteins that positively regulates aggregate formation. Here, by using nuclear magnetic resonance (NMR) spectroscopy, we examine the mechanism of action of MOAG-4 by characterizing its interaction with α-synuclein (αSyn)...
March 23, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28335343/photoelectrochemical-performance-observed-in-mn-doped-bifeo%C3%A2-heterostructured-thin-films
#8
Hao-Min Xu, Huanchun Wang, Ji Shi, Yuanhua Lin, Cewen Nan
Pure BiFeO₃ and heterostructured BiFeO₃/BiFe0.95Mn0.05O₃ (5% Mn-doped BiFeO₃) thin films have been prepared by a chemical deposition method. The band structures and photosensitive properties of these films have been investigated elaborately. Pure BiFeO₃ films showed stable and strong response to photo illumination (open circuit potential kept -0.18 V, short circuit photocurrent density was -0.023 mA·cm(-2)). By Mn doping, the energy band positions shifted, resulting in a smaller band gap of BiFe0...
November 16, 2016: Nanomaterials
https://www.readbyqxmd.com/read/28335326/tuning-the-emission-energy-of-chemically-doped-graphene-quantum-dots
#9
Noor-Ul-Ain, Martin O Eriksson, Susann Schmidt, M Asghar, Pin-Cheng Lin, Per Olof Holtz, Mikael Syväjärvi, G Reza Yazdi
Tuning the emission energy of graphene quantum dots (GQDs) and understanding the reason of tunability is essential for the GOD function in optoelectronic devices. Besides material-based challenges, the way to realize chemical doping and band gap tuning also pose a serious challenge. In this study, we tuned the emission energy of GQDs by substitutional doping using chlorine, nitrogen, boron, sodium, and potassium dopants in solution form. Photoluminescence data obtained from (Cl- and N-doped) GQDs and (B-, Na-, and K-doped) GQDs, respectively exhibited red- and blue-shift with respect to the photoluminescence of the undoped GQDs...
November 3, 2016: Nanomaterials
https://www.readbyqxmd.com/read/28335219/post-plasma-siox-coatings-of-metal-and-metal-oxide-nanoparticles-for-enhanced-thermal-stability-and-tunable-photoactivity-applications
#10
Patrick Post, Nicolas Jidenko, Alfred P Weber, Jean-Pascal Borra
The plasma-based aerosol process developed for the direct coating of particles in gases with silicon oxide in a continuous chemical vapor deposition (CVD) process is presented. It is shown that non-thermal plasma filaments induced in a dielectric barrier discharge (DBD) at atmospheric pressure trigger post-DBD gas phase reactions. DBD operating conditions are first scanned to produce ozone and dinitrogen pentoxide. In the selected conditions, these plasma species react with gaseous tetraethyl orthosilicate (TEOS) precursor downstream of the DBD...
May 13, 2016: Nanomaterials
https://www.readbyqxmd.com/read/28334000/temperature-and-food-quantity-effects-on-the-harpacticoid-copepod-nitocra-spinipes-combining-in-vivo-bioassays-with-population-modeling
#11
Josef Koch, Thuy T Bui, Elin Lundström Belleza, Markus Brinkmann, Henner Hollert, Magnus Breitholtz
The harpacticoid copepod Nitocra spinipes has become a popular model species for toxicity testing over the past few decades. However, the combined influence of temperature and food shortage, two climate change-related stressors, has never been assessed in this species. Consequently, effects of three temperatures (15, 20 and 25°C) and six food regimes (between 0 and 5 × 105 algal cells/mL) on the life cycle of N. spinipes were examined in this study. Similarly to other copepod species, development times and brood sizes decreased with rising temperatures...
2017: PloS One
https://www.readbyqxmd.com/read/28333540/current-state-of-the-art-mri-for-comprehensive-evaluation-of-potential-living-liver-donors
#12
Kartik S Jhaveri, Lijun Guo, Luís Guimarães
OBJECTIVE: This review focuses on the role of state-of-the-art MRI-based techniques for comprehensive evaluation of living donors providing single-visit assessment of the liver vasculature via MR angiography, of the biliary tract via conventional T2-weighted MR cholangiography and T1-weighted gadoxetate disodium-enhanced MR cholangiography, and of hepatic steatosis via T2*-corrected multiecho chemical shift-based water-fat separation MRI and high-speed T2-corrected multiecho MR spectroscopy...
March 23, 2017: AJR. American Journal of Roentgenology
https://www.readbyqxmd.com/read/28332773/determination-of-conduction-and-valence-band-electronic-structure-of-latioxny-thin-film
#13
Markus Pichler, Jakub Szlachetko, Ivano Eligio Castelli, Nicola Marzari, Max Döbeli, Alexander Wokaun, Daniele Pergolesi, Thomas Lippert
The nitrogen substitution into the oxygen sites of several oxide materials leads to a reduction of the band gap to the visible light energy range, which makes these oxynitride semiconductors potential photocatalysts for efficient solar water splitting. Oxynitrides typically show a different crystal structure compare to the pristine oxide material. Since the band gap is correlated to both the chemical composition and the crystal structure, it is not trivial to distinguish what modifications of the electronic structure induced by the nitrogen substitution are related to compositional and/or structural effects...
March 23, 2017: ChemSusChem
https://www.readbyqxmd.com/read/28330994/combining-dnp-nmr-with-segmental-and-specific-labeling-to-study-a-yeast-prion-protein-strain-that-is-not-parallel-in-register
#14
Kendra K Frederick, Vladimir K Michaelis, Marc A Caporini, Loren B Andreas, Galia T Debelouchina, Robert G Griffin, Susan Lindquist
The yeast prion protein Sup35NM is a self-propagating amyloid. Despite intense study, there is no consensus on the organization of monomers within Sup35NM fibrils. Some studies point to a β-helical arrangement, whereas others suggest a parallel in-register organization. Intermolecular contacts are often determined by experiments that probe long-range heteronuclear contacts for fibrils templated from a 1:1 mixture of (13)C- and (15)N-labeled monomers. However, for Sup35NM, like many large proteins, chemical shift degeneracy limits the usefulness of this approach...
March 22, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28329727/theoretical-study-on-the-alkylation-of-o-xylene-with-styrene-in-alcl3-ionic-liquid-catalytic-system
#15
Bobo Cao, Jiuyao Du, Ziping Cao, Haitao Sun, Xuejun Sun, Hui Fu
To explore sustainable catalysts with innovative mechanisms, the alkylation mechanism of o-xylene with styrene was studied using DFT method in AlCl3-ionic liquid catalytic system. The reaction pathway was consisted of CC coupling and a hydrogen shift, in which two transition states were found and further discussed. The reactive energy catalyzed by superelectrophilic AlCl2(+) (12.6kcal/mol) was distinctly lower than AlCl3 (43.0kcal/mol), which was determined as the rate-determining step. Mulliken charge along IRC gave a comprehensive understanding of charge distribution and electron transfer in dynamic progress...
March 6, 2017: Journal of Molecular Graphics & Modelling
https://www.readbyqxmd.com/read/28329418/covalent-crosslinking-of-graphene-quantum-dots-by-mcmurry-deoxygenation-coupling
#16
Shaowei Chen, Limei Chen, Peiguangf Hu, Jia En Lu
Graphene quantum dots were covalently crosslinked forming ensembles of a few hundred nanometers in size by McMurry deoxygenation coupling reactions of peripheral carbonyl functional moieties catalyzed by TiCl4 and Zn powders in refluxing THF, as manifested in TEM, AFM, FTIR, Raman and XPS measurements. Photoluminescence measurements showed that after chemical coupling, the excitation and emisison peaks blue-shifted somewhat and the emission intensity increased markedly, likely due to the removal of oxygenated species where quinone-like species were known to be effective electron-acceptors and emission quenchers...
March 22, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28328542/an-excited-state-intramolecular-photon-transfer-fluorescence-probe-for-localizable-live-cell-imaging-of-cysteine
#17
Wei Liu, Wen Chen, Si-Jia Liu, Jian-Hui Jiang
Small molecule probes suitable for selective and specific fluorescence imaging of some important but low-concentration intracellular reactive sulfur species such as cysteine (Cys) pose a challenge in chemical biology. We present a readily available, fast-response fluorescence probe CHCQ-Ac, with 2-(5'-chloro-2-hydroxyl-phenyl)-6-chloro-4(3 H)-quinazolinone (CHCQ) as the fluorophore and acrylate group as the functional moiety, that enables high-selectivity and high-sensitivity for detecting Cys in both solution and biological system...
March 22, 2017: Methods and Applications in Fluorescence
https://www.readbyqxmd.com/read/28328211/the-water-solvent-effect-on-theoretical-evaluation-of-1h-nmr-chemical-shifts-the-o-methyl-inositol-isomer
#18
Helio F Dos Santos, Marcelo Chagas, Leonardo De Souza, Willian Rocha, Mauro V De Almeida, Cleber P A Anconi, Wagner Batista De Almeida
In this paper, density functional theory calculations of nuclear magnetic resonance (NMR) chemical shifts for L-quebrachitol isomer, previously studied in our group (Mag. Res. Chem. 50 (2012) 608-614) are reported aiming to investigate in more details the water solvent effect on the prediction of 1H NMR spectra. In order to include explicit water molecules, twenty water-L-quebrachitol configurations obtained from Monte Carlo simulation were selected to perform geometry optimizations using the effective fragment potential method encompassing 60 water molecules around the solute...
March 22, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28328174/a-strategy-to-design-hyperpolarized-%C3%A2-%C3%A2-c-magnetic-resonance-probes-using-1-%C3%A2-%C3%A2-c-%C3%AE-amino-acid-as-a-scaffold-structure
#19
Tatsuya Nishihara, Yutaka Kameyama, Hiroshi Nonaka, Yoichi Takakusagi, Fuminori Hyodo, Kazuhiro Ichikawa, Shinsuke Sando
Hyperpolarization is an emerging method that dramatically enhances NMR signal intensity. As a result of the increased sensitivity, hyperpolarized (HP) NMR molecular probes can be used to perform time-resolved spectroscopy and imaging in vitro and in vivo. It is however challenging to design such probes de novo. We herein report the [1-¹³C]α-amino acid as a scaffold structure to design HP ¹³C NMR molecular probe. The [1-¹³C]α-amino acid can be converted to various HP ¹³C chemical probes that show sufficient chemical shift change by altering the chemical state of α-nitrogen upon the interaction with the target...
March 22, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28327743/spatially-composition-modulated-two-dimensional-ws2xse2-1-x-nanosheets
#20
Xueping Wu, Honglai Li, Hongjun Liu, Xiujuan Zhuang, Xiao Wang, Xiaopeng Fan, Xidong Duan, Xiaoli Zhu, Qinglin Zhang, Alfred J Meixner, Xiangfeng Duan, Anlian Pan
Controllable synthesis of two-dimensional (2D) transition-metal dichalcogenides (TMDs) with tunable bandgaps is vital for their applications in nanophotonics, due to its efficient modulation of the physical and chemical properties of these atomic layered nanostructures. Here we report for the first time, the controllable synthesis of spatially composition-modulated WS2xSe2(1-x) nanosheets and WS2-WS2xSe2(1-x) lateral heterostructures by a developed one-step chemical vapor deposition (CVD) approach, as well as the understanding of their growth mechanism...
March 22, 2017: Nanoscale
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