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https://www.readbyqxmd.com/read/28433002/changes-in-microstructure-of-two-ammonium-based-protic-ionic-liquids-proved-by-in-situ-variable-temperature-1-h-nmr-spectroscopy-influence-of-anion
#1
Xiaochen Tang, Yingjie Xu, Xiao Zhu, Yueqing Lu
In this work, changes in microstructure of two protic ionic liquids (PILs), namely n-butylammonium acetate (N4Ac) and n-butylammonium nitrate (N4NO3 ) are proved by in situ variable-temperature (1) H NMR spectroscopy at the temperature range from 25 °C to 115 °C, and the influence of the nature of anion is discussed accordingly. The results demonstrate that (1) H NMR chemical shifts of alkyl protons of both N4Ac and N4NO3 are almost not changed with the increasing of temperature, due to the absence of hydrogen bond interaction between alkyl protons with anions...
April 22, 2017: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/28432983/improved-resolution-and-simplification-of-the-spin-diffusion-based-nmr-method-for-the-structural-analysis-of-mixed-linker-mofs
#2
Andraž Krajnc, Bart Bueken, Dirk De Vos, Gregor Mali
Nuclear magnetic resonance spectroscopy combined with modeling represents a powerful tool for the structural analysis of heterogeneous materials. In this contribution we describe an upgraded method, particularly suited for the structural analysis of mixed-linker metal-organic framework materials, which is based on the measurement and modeling of proton spin diffusion among constituents. We tested the method on a UiO-66-type metal-organic material, in which the organic building units were 1,4-benzenedicarboxylate and trans-1,4-cyclohexanedicarboxylate anions distributed within the framework in an unknown manner...
April 12, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28432919/synthesis-fluorescence-sensing-and-molecular-logic-of-two-water-soluble-1-8-naphthalimides
#3
Nikolai I Georgiev, Margarita D Dimitrova, Anelia Ts Mavrova, Vladimir B Bojinov
Two novel highly water-soluble fluorescence sensing 1,8-naphthalimides are synthesized and investigated. The novel compounds are designed on the "fluorophore-receptor1-spacer-receptor2" model as a molecular fluorescence probe for determination of cations and anions in 100% aqueous media. The novel probes comprising N-imide and N-phenylpiperazine or morpholine substituents are capable to operate simultaneously via ICT and PET signaling mechanism as a function of pH and to recognize selectively Cu(2+) and Hg(2+) over the other representative metal ions...
April 18, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28432915/proton-induced-production-and-radiochemical-isolation-of-44-ti-from-scandium-metal-targets-for-44-ti-44-sc-generator-development
#4
Valery Radchenko, Jonathan W Engle, Dmitri G Medvedev, Joel M Maassen, Cleo M Naranjo, George A Unc, Catherine A L Meyer, Tara Mastren, Mark Brugh, Leonard Mausner, Cathy S Cutler, Eva R Birnbaum, Kevin D John, F Meiring Nortier, Michael E Fassbender
Scandium-44g (half-life 3.97h) shows promise for application in positron emission tomography (PET), due to favorable decay parameters. One of the sources of (44g)Sc is the (44)Ti/(44g)Sc generator, which can conveniently provide this radioisotope on a daily basis at a diagnostic facility. Titanium-44 (half-life 60.0 a), in turn, can be obtained via proton irradiation of scandium metal targets. A substantial (44)Ti product batch, however, requires high beam currents, long irradiation times and an elaborate chemical procedure for (44)Ti isolation and purification...
April 7, 2017: Nuclear Medicine and Biology
https://www.readbyqxmd.com/read/28432857/on-the-importance-of-intramolecular-hydrogen-bond-cooperativity-in-d-glucose-an-nmr-and-qtaim-approach
#5
John S Lomas, Laurent Joubert
The idea that hydrogen bond cooperativity is responsible for the structure and reactivity of carbohydrates is examined. Density functional theory and gauge-including atomic orbital calculations on the known conformers of the α and β anomers of D-glucopyranose in the gas phase are used to compute proton NMR chemical shifts and interatomic distances, which are taken as criteria for probing intramolecular interactions. Atom-atom interaction energies are calculated by the interacting quantum atoms approach in the framework of the quantum theory of atoms in molecules...
April 22, 2017: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/28432653/analyzing-glycopeptide-isomers-by-combining-differential-mobility-spectrometry-with-electron-and-collision-based-tandem-mass-spectrometry
#6
J Larry Campbell, Takashi Baba, Chang Liu, Catherine S Lane, J C Yves Le Blanc, James W Hager
Differential mobility spectrometry (DMS) has been employed to separate isomeric species in several studies. Under the right conditions, factors such as separation voltage, temperature, the presence of chemical modifiers, and residence time can combine to provide unique signal channels for isomeric species. In this study, we examined a set of glycopeptide isomers, MUC5AC-3 and MUC5AC-13, which bear an N-acetyl-galactosamine (GalNAc) group on either threonine-3 or threonine-13. When analyzed as a mixture, the resulting MS and MS/MS spectra yield fragmentation patterns that cannot discern these convolved species...
April 21, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28432504/3t-mri-of-the-knee-with-optimised-isotropic-3d-sequences-accurate-delineation-of-intra-articular-pathology-without-prolonged-acquisition-times
#7
Osamah M Abdulaal, Louise Rainford, Peter MacMahon, Eoin Kavanagh, Marie Galligan, James Cashman, Allison McGee
OBJECTIVES: To investigate optimised isotropic 3D turbo spin echo (TSE) and gradient echo (GRE)-based pulse sequences for visualisation of articular cartilage lesions within the knee joint. METHODS: Optimisation of experimental imaging sequences was completed using healthy volunteers (n=16) with a 3-Tesla (3T) MRI scanner. Imaging of patients with knee cartilage abnormalities (n=57) was then performed. Acquired sequences included 3D proton density-weighted (PDW) TSE (SPACE) with and without fat-suppression (FS), and T2*W GRE (TrueFISP) sequences, with acquisition times of 6:51, 6:32 and 5:35 min, respectively...
April 21, 2017: European Radiology
https://www.readbyqxmd.com/read/28432403/bone-marrow-fat-content-in-70-adolescent-girls-with-anorexia-nervosa-magnetic-resonance-imaging-and-magnetic-resonance-spectroscopy-assessment
#8
Kirsten Ecklund, Sridhar Vajapeyam, Robert V Mulkern, Henry A Feldman, Jennifer M O'Donnell, Amy D DiVasta, Catherine M Gordon
BACKGROUND: Adolescents and women with anorexia nervosa have increased bone marrow fat and decreased bone formation, at least in part due to hormonal changes leading to preferential stem cell differentiation to adipocytes over osteoblasts. OBJECTIVE: The purpose of this study was to evaluate marrow fat content and correlate with age and disease severity using knee MRI with T1 relaxometry (T1-R) and MR spectroscopy (MRS) in 70 adolescents with anorexia nervosa. MATERIALS AND METHODS: We enrolled 70 girls with anorexia nervosa who underwent 3-T knee MRI with coronal T1-W images, T1-R and single-voxel proton MRS at 30 and 60 ms TE...
April 22, 2017: Pediatric Radiology
https://www.readbyqxmd.com/read/28432188/magnetic-resonance-neurography-visualizes-abnormalities-in-sciatic-and-tibial-nerves-in-patients-with-type-1-diabetes-and-neuropathy
#9
Michael Vaeggemose, Mirko Pham, Steffen Ringgaard, Hatice Tankisi, Niels Ejskjaer, Sabine Heiland, Per L Poulsen, Henning Andersen
This study evaluates whether diffusion-tensor-imaging MR-Neurography (DTI-MRN), T2-relaxation-time and proton-spin-density can detect and grade neuropathic abnormalities in patients with type 1 diabetes.Forty-nine patients with type 1 diabetes (11 with severe polyneuropathy (sDPN), 13 with mild polyneuropathy (mDPN) and 25 without polyneuropathy (nDPN)) and 30 healthy controls (HC) were included. Clinical examinations, nerve-conduction-studies and vibratory-perception-thresholds determined the presence and severity of DPN...
April 21, 2017: Diabetes
https://www.readbyqxmd.com/read/28431962/structural-basis-chemical-driving-forces-and-biological-implications-of-flavones-as-cu-ii-ionophores
#10
Fang Dai, Wen-Jing Yan, Yu-Ting Du, Xia-Zhen Bao, Xiu-Zhuang Li, Bo Zhou
A main biochemical property of cancer cells, compared with normal cells, is altered redox status including increased levels of copper to maintain their malignant phenotypes. Thus, increasing copper accumulation, by using ionophores, to disrupt abnormal redox homeostasis of cancer cells may be an important anticancer strategy. Naturally occurring molecules with extraordinarily diverse chemical scaffolds are an important source of inspiration for developing copper ionophores. Dietary flavonoids are well-characterized copper chelators and show cancer chemopreventive potential, but their ionophoric role for redox-active copper and the related biological implications have remained unknown...
April 18, 2017: Free Radical Biology & Medicine
https://www.readbyqxmd.com/read/28431483/bioassay-guided-isolation-identification-of-compounds-from-origanum-rotundifolium-and-investigation-of-their-antiproliferative-and-antioxidant-activities
#11
Ramazan Erenler, Bilal Meral, Ozkan Sen, Mahfuz Elmastas, Ali Aydin, Ozgur Eminagaoglu, Gulacti Topcu
CONTEXT: Origanum (Lamiaceae) has been used in food and pharmaceutical industries. OBJECTIVE: Isolation and identification of bioactive compounds from Origanum rotundifolium Boiss. and investigation of their antiproliferative and antioxidant activities. MATERIALS AND METHODS: The aerial part of O. rotundifolium was dried and powdered (1.0 kg ±2.0 g) then extracted with hexane, ethyl acetate, methanol and water. Solvent (3 × 1 L) was used for each extraction for a week at room temperature...
December 2017: Pharmaceutical Biology
https://www.readbyqxmd.com/read/28431207/syntheses-of-chroman-2-ones-and-%C3%AE-amino-acids-through-a-diastereoselective-domino-reaction
#12
D Balaji Chandrasekhar, Shwu-Chen Tsay, Tapan K Pradhan, Jih Ru Hwu
Many 3-aminochroman-2-ones and β,β-diarylalanines exhibit significant biological activities. A new method was thus developed for the syntheses of these compounds with high efficiency and diastereoselectivity. First, treatment of various phenols with Erlenmeyer-Plochl (Z)-azlactones and AlCl3 in toluene produced the desired cis-3-aminochroman-2-ones in 65-90% yields under kinetic control. This coupling reaction involved a domino process of Friedel-Crafts alkylation, 1,4-AlCl3 shift, transesterification, and protodealumination in a "single-flask...
April 21, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28430797/effect-of-quinoline-based-1-2-3-triazole-and-its-structural-analogues-on-growth-and-virulence-attributes-of-candida-albicans
#13
Mohammad Irfan, Shadab Alam, Nikhat Manzoor, Mohammad Abid
Candida albicans, along with some other non-albicans Candida species, is a group of yeast, which causes serious infections in humans that can be both systemic and superficial. Despite the fact that extensive efforts have been put into the discovery of novel antifungal agents, the frequency of these fungal infections has increased drastically worldwide. In our quest for the discovery of novel antifungal compounds, we had previously synthesized and screened quinoline containing 1,2,3-triazole (3a) as a potent Candida spp inhibitor...
2017: PloS One
https://www.readbyqxmd.com/read/28430414/dynamic-and-energetic-signatures-of-adenine-tracts-in-a-ra-dt-rna-dna-hybrid-and-in-homologous-rna-dna-rna-rna-and-dna-dna-double-helices
#14
Yuegao Huang, Irina M Russu
Nuclear magnetic resonance spectroscopy and proton exchange are being used to characterize the opening reactions of individual base pairs in the RNA-DNA hybrid 5'-rGCGAUAAAAAGGCC-3'/5'-dGGCCTTTTTATCGC-3'. The hybrid contains a central tract of five rA-dT base pairs. The rates and the equilibrium constant of the opening reaction for each base pair are determined from the dependence of the exchange rates of imino protons on ammonia concentration, at 10°C. The results are compared to those previously obtained by our laboratory for three homologous duplexes of the same base sequence (except for the appropriate T/U substitution), containing tracts of dA-rU, rA-rU or dA-dT base pairs...
April 21, 2017: Biochemistry
https://www.readbyqxmd.com/read/28430398/impact-of-acid-reducing-agents-on-the-pharmacokinetics-of-palbociclib-a-weak-base-with-ph-dependent-solubility-with-different-food-intake-conditions
#15
Wan Sun, Karen J Klamerus, Lisa M Yuhas, Sylvester Pawlak, Anna Plotka, Melissa O'Gorman, Leonid Kirkovsky, Maha Kosa, Diane Wang
Palbociclib free base capsule is a weak base drug with highly pH-dependent solubility. In vitro and in vivo studies evaluated the impact of acid-reducing agents on exposure of palbociclib and determined whether the impact, if any, can be mitigated by food. A drug-drug interaction study (study 1) was conducted first under fasted conditions and showed that coadministration of multiple doses of the proton-pump inhibitor rabeprazole substantially reduced palbociclib mean area under the concentration-time curve from time 0 to infinity and maximum observed plasma concentration by 62% and 80%, respectively...
April 21, 2017: Clinical Pharmacology in Drug Development
https://www.readbyqxmd.com/read/28430281/insertion-of-sodium-phosphaethynolate-na-ocp-into-a-zirconium-benzyne-complex
#16
Jerod M Kieser, Robert J Gilliard, Arnold L Rheingold, Hansjörg Grützmacher, John D Protasiewicz
Reaction of the zirconium-benzyne complex [Cp2Zr(PMe3)(C6H4)] with sodium phosphaethynolate, Na[OCP], affords a zircono-phosphaalkene complex. Notably, unlike reactions of other transition metal complexes with Na[OCP] that yield the products of simple salt metathesis, this transformation represents novel Na[OCP] insertion chemistry and formation of an unusual solid state coordination polymer. The polymer is disrupted upon addition of Me3SiCl to afford a silyl-capped dimer that retains the zirconophosphaalkene functionality...
April 21, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28430191/activating-lattice-oxygen-redox-reactions-in-metal-oxides-to-catalyse-oxygen-evolution
#17
Alexis Grimaud, Oscar Diaz-Morales, Binghong Han, Wesley T Hong, Yueh-Lin Lee, Livia Giordano, Kelsey A Stoerzinger, Marc T M Koper, Yang Shao-Horn
Understanding how materials that catalyse the oxygen evolution reaction (OER) function is essential for the development of efficient energy-storage technologies. The traditional understanding of the OER mechanism on metal oxides involves four concerted proton-electron transfer steps on metal-ion centres at their surface and product oxygen molecules derived from water. Here, using in situ (18)O isotope labelling mass spectrometry, we provide direct experimental evidence that the O2 generated during the OER on some highly active oxides can come from lattice oxygen...
May 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28429940/density-functional-theory-and-car-parrinello-molecular-dynamics-study-of-the-hydrogen-producing-mechanism-of-the-co-dmgbf2-2-and-co-dmgh-2-cobaloxime-complexes-in-the-acetonitrile-water-solvent
#18
Jinfan Chen, Patrick H-L Sit
The catalytic hydrogen-producing processes of two prototypical cobaloxime catalysts Co(dmgBF2)2 (dmgBF2=difluoroboryl-dimethylglyoxime) and Co(dmgH)2 (dmgH=dimethylglyoxime), were studied by Density Functional Theory (DFT) and Car-Parrinello molecular dynamics (CPMD) simulations in the explicit acetonitrile-water solvent. Our study demonstrates the key role of water molecules as shuttles to deliver protons to the cobalt active centers of these catalysts. However, the transfer of protons to the cobalt centers also competes with the diffusion of the proton away from the complex via the hydrogen bond network of water...
April 21, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28429299/participation-of-c-h-protons-in-the-dissociation-of-a-proton-deficient-dipeptide
#19
Damodar Koirala, Sabyasachy Mistry, Paul G Wenthold
The dissociation of anionic dipeptides Phe*Gly and GlyPhe*, where Phe* refers to sulfonated phenyl alanine, has been investigated by using ion trap mass spectrometry. The dipeptides undergo collision-induced dissociation (CID) to give the same products, indicating that they rearrange to a common structure before dissociation. The rearrangement does not occur with the dipeptide methyl esters. The structures of the b2 ions were investigated to determine the effect that having a remote, anionic site has on product formation...
April 20, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28429247/a-review-of-the-novel-application-and-potential-adverse-effects-of-proton-pump-inhibitors
#20
REVIEW
Li-Yuan Yu, Lu-Ning Sun, Xue-Hui Zhang, Yue-Qi Li, Lei Yu, Zi-Qing-Yun Yuan, Ling Meng, Hong-Wen Zhang, Yong-Qing Wang
Proton pump inhibitors (PPIs) are known as a class of pharmaceutical agents that target H(+)/K(+)-ATPase, which is located in gastric parietal cells. PPIs are widely used in the treatment of gastric acid-related diseases including peptic ulcer disease, erosive esophagitis and gastroesophageal reflux disease, and so on. These drugs present an excellent safety profile and have become one of the most commonly prescribed drugs in primary and specialty care. Except for gastric acid-related diseases, PPIs can also be used in the treatment of Helicobacter pylori infection, viral infections, respiratory system diseases, cancer and so on...
April 20, 2017: Advances in Therapy
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