keyword
MENU ▼
Read by QxMD icon Read
search

chemical shift

keyword
https://www.readbyqxmd.com/read/28651375/chromatographic-and-computational-assessment-of-lipophilicity-of-new-anticancer-acetylenequinoline-derivatives
#1
Krzysztof Marciniec, Stanislaw Boryczka
The lipophilicity of a series of anticancer propargylquinoline derivatives is investigated using both chromatographic and computational methods. The parameters of the tested compounds' relative lipophilicity (logkw) are determined experimentally by the high-performance liquid chromatographic method (RP-HPLC, Accucore C18 column), using mixtures of acetonitrile and water as mobile phases. Mobile phase acetonitrile concentrations range between 50 and 80%. The logk values of the investigated compounds are linearly dependent upon the acetonitrile concentration...
June 23, 2017: Journal of Chromatographic Science
https://www.readbyqxmd.com/read/28651245/high-resolution-hyperpolarized-in-vivo-metabolic-13-c-spectroscopy-at-low-magnetic-field-48-7mt-following-murine-tail-vein-injection
#2
Aaron M Coffey, Matthew A Feldman, Roman V Shchepin, Danila A Barskiy, Milton L Truong, Wellington Pham, Eduard Y Chekmenev
High-resolution (13)C NMR spectroscopy of hyperpolarized succinate-1-(13)C-2,3-d2 is reported in vitro and in vivo using a clinical-scale, biplanar (80cm-gap) 48.7mT permanent magnet with a high homogeneity magnetic field. Non-localized (13)C NMR spectra were recorded at 0.52MHz resonance frequency over the torso of a tumor-bearing mouse every 2s. Hyperpolarized (13)C NMR signals with linewidths of ∼3Hz (corresponding to ∼6ppm) were recorded in vitro (2mL in a syringe) and in vivo (over a mouse torso). Comparison of the full width at half maximum (FWHM) for (13)C NMR spectra acquired at 48...
June 15, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28650016/prediction-of-1-h-nmr-chemical-shifts-for-clusters-of-imidazolium-based-ionic-liquids
#3
Su Chen, Ekaterina I Izgorodina
Nuclear magnetic resonance (NMR) has been widely used to elucidate the bulk structure of ionic liquids. In this work, we calculated (1)H NMR chemical shifts of 1-ethyl-3-methylimidazolium (C2mim(+)) ionic liquids combined with various anions such as chloride (Cl), tetrafluoroborate (BF4), hexafluorophosphate (PF6), acetate (OAc), trifluoroacetate (TFA), and dicyanamide (DCA). The previously established level of theory, HF/6-311G+(3df,2p), was used for the accurate prediction of NMR chemical shifts both in gas phase and in solvents with varying dielectric constant such as CHCl3 and ethanol...
June 26, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28649731/protein-glycan-quinary-interactions-in-crowding-environment-unveiled-by-nmr-spectroscopy
#4
Ana Diniz, Jorge S Dias, Jesús Jiménez-Barbero, Filipa Marcelo, Eurico J Cabrita
Protein-glycan interactions as modulators for quinary structure in crowding environments were explored. The interaction between human galectin 3 (Gal-3) and distinct macromolecular crowders, such as bovine and human serum albumin (BSA and HSA), Ficoll 70 and PEG3350, was scrutinized. The molecular recognition event of the specific ligand, lactose, by Gal-3 in crowding conditions was evaluated. Gal-3 interactions were monitored by NMR analysing chemical shift perturbation (CSP) and line broadening of 1H15N-HSQC signals...
June 25, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28648063/chiral-discrimination-of-diamines-by-a-binaphthalene-bridged-porphyrin-dimer
#5
Wenxin Lu, Huifang Yang, Xinyao Li, Chiming Wang, Xiaopeng Zhan, Dongdong Qi, Yongzhong Bian, Jianzhuang Jiang
A pair of 1,1'-binaphthalene-bridged bisporphyrins, (R)- and (S)-H1, were designed to examine their chiral discrimination abilities toward a range of model diamines by using UV-vis absorption, CD, and (1)H NMR spectroscopy with the assistance of DFT molecular modeling. The spectroscopic titrations revealed that (R)-/(S)-H1 could encapsulate (R)-/(S)-DACH and (R)-/(S)-PPDA in the chiral bisporphyrin cavities, leading to the selective formation of sandwich-type 1:1 complexes via dual Zn-N coordination interactions...
June 24, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28647789/probing-slow-timescale-dynamics-in-proteins-using-methyl-1-h-cest
#6
Tairan Yuwen, Rui Huang, Lewis E Kay
Although (15)N- and (13)C-based chemical exchange saturation transfer (CEST) experiments have assumed an important role in studies of biomolecular conformational exchange, (1)H CEST experiments are only beginning to emerge. We present a methyl-TROSY (1)H CEST experiment that eliminates deleterious (1)H-(1)H NOE dips so that CEST profiles can be analyzed robustly to extract methyl proton chemical shifts of rare protein conformers. The utility of the experiment, along with a version that is optimized for (13)CHD2 labeled proteins, is established through studies of exchanging protein systems...
June 24, 2017: Journal of Biomolecular NMR
https://www.readbyqxmd.com/read/28647587/sampling-frequency-for-water-quality-variables-in-streams-systems-analysis-to-quantify-minimum-monitoring-rates
#7
Nick A Chappell, Timothy D Jones, Wlodek Tych
Insufficient temporal monitoring of water quality in streams or engineered drains alters the apparent shape of storm chemographs, resulting in shifted model parameterisations and changed interpretations of solute sources that have produced episodes of poor water quality. This so-called 'aliasing' phenomenon is poorly recognised in water research. Using advances in in-situ sensor technology it is now possible to monitor sufficiently frequently to avoid the onset of aliasing. A systems modelling procedure is presented allowing objective identification of sampling rates needed to avoid aliasing within strongly rainfall-driven chemical dynamics...
June 19, 2017: Water Research
https://www.readbyqxmd.com/read/28647482/isolation-and-structural-characterization-of-dihydrobenzofuran-congeners-of-licochalcone-a
#8
Charlotte Simmler, David C Lankin, Dejan Nikolić, Richard B van Breemen, Guido F Pauli
In an effort to explore the residual complexity of naturally occurring chalcones from the roots of Glycyrrhiza inflata (Fabaceae), two new licochalcone A (LicA) derivatives were isolated as trace metabolites from enriched fractions. Both constituents contain a dihydrofuran moiety linked to carbons C-4 and C-5 of the retrochalcone core. Compound 1 (LicAF1) represents a new chemical entity, whereas compound 2 (LicAF2) has previously been reported as a Lewis acid catalyzed rearrangement of LicA. Evaluation of chirality revealed that both dihydrofuran derivatives existed as a mixture of R and S enantiomers...
June 21, 2017: Fitoterapia
https://www.readbyqxmd.com/read/28647239/fluoride-removal-by-al-ti-and-fe-hydroxides-and-coexisting-ion-effect
#9
Jianfeng Zhang, Timothy E Brutus, Jiemin Cheng, Xiaoguang Meng
Batch experiments were conducted to evaluate fluoride removal by Al, Fe, and Ti-based coagulants and adsorbents, as well as the effects of coexisting ions and formation of aluminum-fluoride complexes on fluoride removal by co-precipitation with alum (Al2(SO4)3·18H2O). Aluminum sulfate was more efficient than the other coagulants for fluoride removal in the pH range between 6 and 8. Nano-crystalline TiO2 was more effective for fluoride removal than Al and Fe hydroxides in a pH range of 3-5. Coexisting anions in water decreased the removal of fluoride in the order: phosphate (2...
July 2017: Journal of Environmental Sciences (China)
https://www.readbyqxmd.com/read/28646781/%C3%AE-potential-evidences-silanol-heterogeneity-induced-by-metal-contaminants-at-the-quartz-surface-implications-in-membrane-damage
#10
Cristina Pavan, Francesco Turci, Maura Tomatis, Mara Ghiazza, Dominique Lison, Bice Fubini
Among the physico-chemical features responsible for the so-called "variability of quartz hazard", a key role has been assigned to the silica surface charge, evaluated by means of ζ potential measurement. The ζ potential of silica describes the protonation state of silanols which, in turn, determine interactions with cell membranes. To gain a molecular understanding of the role of silanols in silica pathogenicity, we conducted a systematic investigation of the variation of the ζ potential as a function of pH (ζ plot titration curve) on a large set of respirable quartz particles with different levels of metal contaminants...
June 13, 2017: Colloids and Surfaces. B, Biointerfaces
https://www.readbyqxmd.com/read/28646173/transmembrane-interactions-of-full-length-mammalian-bitopic-cytochrome-p450-cytochrome-b5-complex-in-lipid-bilayers-revealed-by-sensitivity-enhanced-dynamic-nuclear-polarization-solid-state-nmr-spectroscopy
#11
Kazutoshi Yamamoto, Marc A Caporini, Sang-Choul Im, Lucy Waskell, Ayyalusamy Ramamoorthy
The dynamic protein-protein and protein-ligand interactions of integral bitopic membrane proteins with a single membrane-spanning helix play a plethora of vital roles in the cellular processes associated with human health and diseases, including signaling and enzymatic catalysis. While an increasing number of high-resolution structural studies of membrane proteins have successfully manifested an in-depth understanding of their biological functions, intact membrane-bound bitopic protein-protein complexes pose tremendous challenges for structural studies by crystallography or solution NMR spectroscopy...
June 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28645029/phytoavailability-of-cr-in-silene-vulgaris-the-role-of-soil-plant-genotype-and-bacterial-rhizobiome
#12
P García-Gonzalo, A E Pradas Del Real, M Pirredda, M J Gismera, M C Lobo, A Pérez-Sanz
Understanding the metal behavior at the soil-root interface is of utmost significance for a successful implementation of phytoremediation. In this study, we investigated the differences in chromium (Cr) uptake, chemical changes in soil solution and the shifts in rhizosphere bacterial communities of two genotypes of Silene vulgaris (SV21, SV38) with different tolerance to Cr. A greenhouse experiment was performed in two soils that differed on pH and organic matter (OM) content. An industrial sludge with high content in Cr was used as pollution source...
June 20, 2017: Ecotoxicology and Environmental Safety
https://www.readbyqxmd.com/read/28644553/structural-insights-into-the-inclusion-complexes-between-clomiphene-citrate-and-%C3%AE-cyclodextrin-the-mechanism-of-preferential-isomeric-selection
#13
Arti Maheshwari, Harish Saraswat, Santosh Kumar Upadhyay
A major challenge in pharmaceuticals for clinical applications is to alter the solubility, stability, and toxicity of drug molecules in living systems. Cyclodextrins (CDs) have the ability to form host-guest inclusion complexes with pharmaceuticals for further development of new drug formulations. The inclusion complex of clomiphene citrate (CL), a poorly water-soluble drug, with native β-cyclodextrin (β-CD) was characterized by a one and two-dimensional nuclear magnetic resonance (NMR) spectroscopic approach and also by molecular docking techniques...
June 23, 2017: Chirality
https://www.readbyqxmd.com/read/28644511/bacteriophage-tail-tube-assembly-studied-by-proton-detected-4d-solid-state-nmr
#14
Maximilian Zinke, Pascal Fricke, Camille Samson, Songhwan Hwang, Joseph Wall, Sascha Lange, Sophie Zinn-Justin, Adam Lange
Obtaining unambiguous resonance assignments remains a major bottleneck in solid-state NMR studies of protein structure and dynamics. Particularly for supramolecular assemblies with large subunits (>150 residues), the analysis of crowded spectral data presents a challenge, even if three-dimensional (3D) spectra are used. Here, we present a proton-detected 4D solid-state NMR assignment procedure that is tailored for large assemblies. The key to recording 4D spectra with three indirect carbon or nitrogen dimensions with their inherently large chemical shift dispersion lies in the use of sparse non-uniform sampling (as low as 2%)...
June 23, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28644017/spectrally-undiscerned-isomers-might-lead-to-erroneous-determination-of-water-exchange-rates-of-paracest-eu-iii-agents
#15
Nevenka Cakić, Ben Tickner, Moritz Zaiss, David Esteban-Gómez, Carlos Platas-Iglesias, Goran Angelovski
We report a detailed study of the solution structure and water exchange rate of a Eu(III) complex with the cyclen-based ligand L(1), containing (S)-2-(2-acetamido)-3-(4-(trifluoromethyl)phenyl)propanoate pendant arms at positions 1 and 7 of the cyclen ring and acetylglycinate pendants at positions 4 and 10. The EuL(1) complex was characterized by a combination of NMR and luminescence spectroscopy and density functional theory (DFT) calculations. The chemical exchange saturation transfer (CEST) spectra obtained at different temperatures and saturation powers present a CEST signal attributed to the coordinated water molecule...
June 23, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28643168/self-aggregation-of-synthetic-zinc-methyl-20-substituted-3-hydroxymethyl-pyropheophorbides-as-models-of-bacteriochlorophyll-c
#16
Ayaka Wada, Hitoshi Tamiaki
Zinc 3-hydroxymethyl-13(1)-oxo-chlorins bearing a variety of primary alkyl groups at the 20-position were prepared as models of bacteriochlorophyll-c by chemical modification of naturally occurring chlorophyll-a. The synthetic chlorophyll-a derivatives self-aggregated in an aqueous Triton X-100 solution to afford large oligomers whose Soret and Qy bands were red-shifted and broadened, compared with the bands of their monomers in tetrahydrofuran. The oligomeric bands are similar to those of bacteriochlorophyll-c self-aggregates in chlorosomes, the main light-harvesting antennae of photosynthetic green bacteria...
June 22, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28642235/atomic-layered-au-clusters-on-%C3%AE-moc-as-catalysts-for-the-low-temperature-water-gas-shift-reaction
#17
Siyu Yao, Xiao Zhang, Wu Zhou, Rui Gao, Wenqian Xu, Yifan Ye, Lili Lin, Xiaodong Wen, Ping Liu, Bingbing Chen, Ethan Crumlin, Jinghua Guo, Zhijun Zuo, Weizhen Li, Jinglin Xie, Li Lu, Christopher J Kiely, Lin Gu, Chuan Shi, José A Rodriguez, Ding Ma
The water-gas shift (WGS) reaction (CO+H2O=H2+CO2) is an essential process for hydrogen generation and CO removal in various energy-related chemical operations. This equilibrium-limited reaction is favored at a low working temperature. Potential application in fuel cells also requires a WGS catalyst to be highly active, stable and energy-efficient and match the working temperature of on-site hydrogen generation and consumption units. We synthesized Au layered clusters on an α-MoC substrate to create an interfacial catalyst system for the ultra-low-temperature WGS reaction...
June 22, 2017: Science
https://www.readbyqxmd.com/read/28641423/dynamics-magnetic-properties-and-electron-binding-energies-of-h2o2-in-water
#18
Benedito J C Cabral
Results for the magnetic properties and electron binding energies of H2O2 in liquid water are presented. The adopted methodology relies on the combination of Born-Oppenheimer molecular dynamics and electronic structure calculations. The Keal-Tozer functional was applied for predicting magnetic shieldings and H2O2 intramolecular spin-spin coupling constants. Electron binding energies were calculated with electron propagator theory. In water, H2O2 is a better proton donor than proton acceptor, and the present results indicate that this feature is important for understanding magnetic properties in solution...
June 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28640614/role-of-polymeric-coating-on-the-phosphate-availability-as-fertilizer-insight-from-phosphate-release-in-soil-castor-polyurethane-coatings
#19
Diego Cruz, Ricardo Bortoletto-Santos, Gelton Guimarães, Wagner Luiz Polito, Caue Ribeiro
The coating of fertilizers with polymers is an acknowledged strategy for controlling the release of nutrients and their availability in soil. However, its effectiveness in the case of soluble phosphate fertilizers is still uncertain, and information is lacking concerning the chemical properties and structures of such coatings. Here, an oil-based hydrophobic polymer system (polyurethane) is proposed for control of the release of phosphorus from diammonium phosphate (DAP) granules. This material was systematically characterized, with evaluation of the delivery mechanism and the availability of phosphate in an acid soil...
June 22, 2017: Journal of Agricultural and Food Chemistry
https://www.readbyqxmd.com/read/28639310/high-resolution-31-p-echo-planar-spectroscopic-imaging-in-vivo-at-7t
#20
Andreas Korzowski, Peter Bachert
PURPOSE: Conventional (31) P chemical shift imaging is time-consuming and yields only limited spatial resolution. The purpose of this study was to demonstrate feasibility of (31) P echo-planar spectroscopic imaging (EPSI) in vivo at 7T. METHODS: A 3D (31) P EPSI sequence with trapezoidal-shaped gradient pulses was implemented on a 7T MR scanner. To increase spectral width with reduced demand on gradient performance, a multishot approach was chosen. Acquisition weighting and (31) P-{(1) H} double resonance for nuclear Overhauser signal enhancement were applied to increase sensitivity...
June 21, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
keyword
keyword
54133
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"