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https://www.readbyqxmd.com/read/29908414/synthesis-and-photophysical-properties-of-deuteration-of-pirfenidone
#1
Qiuju Yin, Yujie Chen, Meng Zhou, Xiangsheng Jiang, Junjun Wu, Yang Sun
In order to improve the metabolism of pirfenidone (5-methyl-1-phenylpyridin-2-one, PFD), the methyl-deuterated version of pirfenidone via the substitution of hydrogen (H) at C-5 by its isotope deuterium (D, 5D-PFD) was synthesized and its photophysical properties were investigated. The negative solvatochrom was observed in absorption and fluorescence spectra with increasing solvent polarity, which implied that intermolecular charge transfer (ICT) involved n → π* transition for both of PFD and 5D-PFD...
June 7, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/29907328/proapoptotic-cyclic-peptide-bc71-targets-cell-surface-grp78-and-functions-as-an-anticancer-therapeutic-in-mice
#2
Chieh Kao, Ritu Chandna, Abhijeet Ghode, Charlotte Dsouza, Mo Chen, Andreas Larsson, Siau Hoi Lim, Minjun Wang, Zhonglian Cao, Yizhun Zhu, Ganesh S Anand, Ruowen Ge
Glucose regulated protein 78 kDa (GRP78) is a recently emerged target for cancer therapy and a biomarker for cancer prognosis. Overexpression of GRP78 is observed in many types of cancers, with the cell-surface GRP78 being preferentially present in cancer cells and cancer blood vessel endothelial cells. Isthmin (ISM) is a secreted high-affinity proapoptotic protein ligand of cell-surface GRP78 that suppresses angiogenesis and tumor growth in mice. The C-terminal AMOP (adhesion-associated domain in MUC4 and other proteins) domain of ISM is critical in mediating its interaction with human umbilical vein endothelial cells (HUVECs)...
June 12, 2018: EBioMedicine
https://www.readbyqxmd.com/read/29907032/theoretical-description-of-quantum-mechanical-permeation-of-graphene-membranes-by-charged-hydrogen-isotopes
#3
James W Mazzuca, Nathaniel K Haut
It has been recently shown that in the presence of an applied voltage, hydrogen and deuterium nuclei can be separated from one another using graphene membranes as a nuclear sieve, resulting in a 10-fold enhancement in the concentration of the lighter isotope. While previous studies, both experimental and theoretical, have attributed this effect mostly to differences in vibrational zero point energy (ZPE) of the various isotopes near the membrane surface, we propose that multi-dimensional quantum mechanical tunneling of nuclei through the graphene membrane influences this proton permeation process in a fundamental way...
June 14, 2018: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29906163/probing-long-range-neutrino-mediated-forces-with-atomic-and-nuclear-spectroscopy
#4
Yevgeny V Stadnik
The exchange of a pair of low-mass neutrinos between electrons, protons, and neutrons produces a "long-range" 1/r^{5} potential, which can be sought for in phenomena originating on the atomic and subatomic length scales. We calculate the effects of neutrino-pair exchange on transition and binding energies in atoms and nuclei. In the case of atomic s-wave states, there is a large enhancement of the induced energy shifts due to the lack of a centrifugal barrier and the highly singular nature of the neutrino-mediated potential...
June 1, 2018: Physical Review Letters
https://www.readbyqxmd.com/read/29893556/ni-catalyzed-regioselective-%C3%AE-%C3%AE-diarylation-of-unactivated-olefins-in-ketimines-via-ligand-enabled-contraction-of-transient-nickellacycles-rapid-access-to-remotely-diarylated-ketones
#5
Prakash Basnet, Roshan K Dhungana, Surendra Thapa, Bijay Shrestha, Shekhar Kc, Jeremiah M Sears, Ramesh Giri
We disclose a [(PhO)3P]/NiBr2-catalyzed regioselective β,δ-diarylation of unactivated olefins in ketimines with aryl halides and arylzinc reagents. This diarylation proceeds at remote locations to the carbonyl group to afford, after simple H+ workup, diversely substituted β,δ-diarylketones that are otherwise difficult to access readily with existing methods. Deuterium-labelling and crossover experiments indicate that diarylation proceeds by ligand-enabled contraction of transient nickellacycles.
June 12, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29891892/interplay-of-water-and-reactive-elements-in-oxidation-of-alumina-forming-alloys
#6
N Mortazavi, C Geers, M Esmaily, V Babic, M Sattari, K Lindgren, P Malmberg, B Jönsson, M Halvarsson, J E Svensson, I Panas, L G Johansson
High-temperature alloys are crucial to many important technologies that underpin our civilization. All these materials rely on forming an external oxide layer (scale) for corrosion protection. Despite decades of research on oxide scale growth, many open questions remain, including the crucial role of the so-called reactive elements and water. Here, we reveal the hitherto unknown interplay between reactive elements and water during alumina scale growth, causing a metastable 'messy' nano-structured alumina layer to form...
June 11, 2018: Nature Materials
https://www.readbyqxmd.com/read/29882873/importance-of-hydrophilic-groups-on-modulating-the-structural-mechanical-and-interfacial-properties-of-bilayers-a-comparative-molecular-dynamics-study-of-phosphatidylcholine-and-ion-pair-amphiphile-membranes
#7
Ching-An Tian, Chi-Cheng Chiu
An ion pair amphiphile (IPA), a molecular complex composed of two oppositely charged amphiphiles, is a phospholipid mimic which differs from a phospholipid only in the hydrophilic compositions. Here, we utilized molecular dynamics (MD) simulations to compare the bilayer systems composed of phosphatidylcholines (PC) and alkyltrimethylammonium-alkylsulfate IPAs with various alkyl chain lengths. The membrane properties for both liquid-disordered (Ld) and gel (S) phase bilayers were examined via running simulations above and below the main transition temperatures...
May 23, 2018: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/29880012/albumin-mass-balance-and-kinetics-in-liver-transplantation
#8
Mariam Amouzandeh, Greg Nowak, Anna Januszkiewicz, Jan Wernerman, Olav Rooyackers, Åke Norberg
BACKGROUND: In major abdominal surgery albumin is shifted from the circulation, presumably leaking into the interstitial space, contributing to a 30-40% decrease in plasma albumin concentration. During and after liver transplantation exogenous albumin is infused for volume substitution and to maintain plasma albumin concentration. Here we used liver transplantation as a model procedure for the study of albumin mass balance and kinetics during major abdominal surgery with albumin substitution...
June 7, 2018: Critical Care: the Official Journal of the Critical Care Forum
https://www.readbyqxmd.com/read/29877215/human-plasma-concentrations-of-trimethylamine-n-oxide-extrapolated-using-pharmacokinetic-modeling-based-on-metabolic-profiles-of-deuterium-labeled-trimethylamine-in-humanized-liver-mice
#9
Makiko Shimizu, Hiroshi Suemizu, Sawa Mizuno, Takashi Kusama, Tomonori Miura, Shotaro Uehara, Hiroshi Yamazaki
Medicinal carnitine-derived and dietary-derived malodorous trimethylamine and its non-malodorous metabolite trimethylamine N-oxide were historically regarded as nontoxic. Clinical and toxicological interest has recently arisen because of their potential association with atherosclerosis. We previously reported a human physiologically based pharmacokinetic (PBPK) model for trimethylamine and its primary metabolite, trimethylamine N-oxide, based on reported rat trimethylamine pharmacokinetics. However, rats are poor metabolizers with respect to trimethylamine N-oxygenation, and this species difference was investigated in vitro using substrate depletion rates in rat and human liver microsomes...
2018: Journal of Toxicological Sciences
https://www.readbyqxmd.com/read/29869117/validating-the-use-of-bioimpedance-spectroscopy-for-assessment-of-fluid-status-in-children
#10
Indranil Dasgupta, David Keane, Elizabeth Lindley, Ihab Shaheen, Kay Tyerman, Franz Schaefer, Elke Wühl, Manfred J Müller, Anja Bosy-Westphal, Hans Fors, Jovanna Dahlgren, Paul Chamney, Peter Wabel, Ulrich Moissl
BACKGROUND: Bioimpedance spectroscopy (BIS) with a whole-body model to distinguish excess fluid from major body tissue hydration can provide objective assessment of fluid status. BIS is integrated into the Body Composition Monitor (BCM) and is validated in adults, but not children. This study aimed to (1) assess agreement between BCM-measured total body water (TBW) and a gold standard technique in healthy children, (2) compare TBW_BCM with TBW from Urea Kinetic Modelling (UKM) in haemodialysis children and (3) investigate systematic deviation from zero in measured excess fluid in healthy children across paediatric age range...
June 4, 2018: Pediatric Nephrology: Journal of the International Pediatric Nephrology Association
https://www.readbyqxmd.com/read/29866098/assessing-the-reliability-of-ftir-spectroscopy-measurements-and-validity-of-bioelectrical-impedance-analysis-as-a-surrogate-measure-of-body-composition-among-children-and-adolescents-aged-8-19-years-attending-schools-in-kampala-uganda
#11
Catherine T Ndagire, John H Muyonga, Dan Isabirye, Benard Odur, Serge M A Somda, Richard Bukenya, Juan E Andrade, Dorothy Nakimbugwe
BACKGROUND: Accurate measurement of body composition in children and adolescents is important as the quantities of fat and fat-free mass have implications for health risk. The objectives of the present study were: to determine the reliability of Fourier Transform Infrared spectroscopy (FTIR) measurements and; compare the Fat Mass (FM), Fat Free Mass (FFM) and body fat percentage (%BF) values determined by bioelectrical impedance analysis (BIA) to those determined by deuterium dilution method (DDM) to identify correlations and agreement between the two methods...
June 4, 2018: BMC Public Health
https://www.readbyqxmd.com/read/29865825/fractal-diffusion-in-high-temperature-polymer-electrolyte-fuel-cell-membranes
#12
Bernhard Hopfenmüller, Reiner Zorn, Olaf Holderer, Oxana Ivanova, Werner Lehnert, Wiebke Lüke, Georg Ehlers, Niina Jalarvo, Gerald J Schneider, Michael Monkenbusch, Dieter Richter
The performance of fuel cells depends largely on the proton diffusion in the proton conducting membrane, the core of a fuel cell. High temperature polymer electrolyte fuel cells are based on a polymer membrane swollen with phosphoric acid as the electrolyte, where proton conduction takes place. We studied the proton diffusion in such membranes with neutron scattering techniques which are especially sensitive to the proton contribution. Time of flight spectroscopy and backscattering spectroscopy have been combined to cover a broad dynamic range...
May 28, 2018: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29864876/plasma-surface-interaction-in-negative-hydrogen-ion-sources
#13
Motoi Wada
A negative hydrogen ion source delivers more beam current when Cs is introduced to the discharge, but a continuous operation of the source reduces the beam current until more Cs is added to the source. This behavior can be explained by adsorption and ion induced desorption of Cs atoms on the plasma grid surface of the ion source. The interaction between the ion source plasma and the plasma grid surface of a negative hydrogen ion source is discussed in correlation to the Cs consumption of the ion source. The results show that operation with deuterium instead of hydrogen should require more Cs consumption and the presence of medium mass impurities as well as ions of the source wall materials in the arc discharge enlarges the Cs removal rate during an ion source discharge...
May 2018: Review of Scientific Instruments
https://www.readbyqxmd.com/read/29864857/review-of-particle-in-cell-modeling-for-the-extraction-region-of-large-negative-hydrogen-ion-sources-for-fusion
#14
D Wünderlich, S Mochalskyy, I M Montellano, A Revel
Particle-in-cell (PIC) codes are used since the early 1960s for calculating self-consistently the motion of charged particles in plasmas, taking into account external electric and magnetic fields as well as the fields created by the particles itself. Due to the used very small time steps (in the order of the inverse plasma frequency) and mesh size, the computational requirements can be very high and they drastically increase with increasing plasma density and size of the calculation domain. Thus, usually small computational domains and/or reduced dimensionality are used...
May 2018: Review of Scientific Instruments
https://www.readbyqxmd.com/read/29864838/deuterium-results-at-the-negative-ion-source-test-facility-elise
#15
W Kraus, D Wünderlich, U Fantz, B Heinemann, F Bonomo, R Riedl
The ITER neutral beam system will be equipped with large radio frequency (RF) driven negative ion sources, with a cross section of 0.9 m × 1.9 m, which have to deliver extracted D- ion beams of 57 A at 1 MeV for 1 h. On the extraction from a large ion source experiment test facility, a source of half of this size is being operational since 2013. The goal of this experiment is to demonstrate a high operational reliability and to achieve the extracted current densities and beam properties required for ITER. Technical improvements of the source design and the RF system were necessary to provide reliable operation in steady state with an RF power of up to 300 kW...
May 2018: Review of Scientific Instruments
https://www.readbyqxmd.com/read/29864368/dual-ion-species-plasma-expansion-from-isotopically-layered-cryogenic-targets
#16
G G Scott, D C Carroll, S Astbury, R J Clarke, C Hernandez-Gomez, M King, A Alejo, I Y Arteaga, R J Dance, A Higginson, S Hook, G Liao, H Liu, S R Mirfayzi, D R Rusby, M P Selwood, C Spindloe, M K Tolley, F Wagner, E Zemaityte, M Borghesi, S Kar, Y Li, M Roth, P McKenna, D Neely
A dual ion species plasma expansion scheme from a novel target structure is introduced, in which a nanometer-thick layer of pure deuterium exists as a buffer species at the target-vacuum interface of a hydrogen plasma. Modeling shows that by controlling the deuterium layer thickness, a composite H^{+}/D^{+} ion beam can be produced by target normal sheath acceleration (TNSA), with an adjustable ratio of ion densities, as high energy proton acceleration is suppressed by the acceleration of a spectrally peaked deuteron beam...
May 18, 2018: Physical Review Letters
https://www.readbyqxmd.com/read/29858839/comprehensive-peptide-ion-structure-studies-using-ion-mobility-techniques-part-3-relating-solution-phase-to-gas-phase-structures
#17
Samaneh Ghassabi Kondalaji, Mahdiar Khakinejad, Stephen J Valentine
Molecular dynamics (MD) simulations have been utilized to study peptide ion conformer establishment during the electrospray process. An explicit water model is used for nanodroplets containing a model peptide and hydronium ions. Simulations are conducted at 300 K for two different peptide ion charge configurations and for droplets containing varying numbers of hydronium ions. For all conditions, modeling has been performed until production of the gas-phase ions and the resultant conformers have been compared to proposed gas-phase structures...
June 1, 2018: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/29858275/molecular-insights-of-inhibition-in-sickle-hemoglobin-polymerization-upon-glutathionylation-hydrogen-deuterium-exchange-mass-spectrometry-and-molecular-dynamics-simulation-based-approach
#18
Rajdeep Das, Amrita Mitra, Gopa Mitra, Dibyajyoti Maity, Vijay Bhat, Debnath Pal, Cecil Ross, Anura V Kurpad, Amit Kumar Mandal
In sickle cell anemia, polymerization of hemoglobin in its deoxy state leads to the formation of insoluble fibres that result in sickling of red blood cells. Stereo-specific binding of isopropyl group of βVal6, the mutated amino acid residue of a tetrameric sickle hemoglobin molecule (HbS), with hydrophobic groove of another HbS tetramer initiates the polymerization. Glutathionylation of βCys93 in HbS was reported to inhibit the polymerization. However, the mechanism of inhibition in polymerization is unknown to date...
June 1, 2018: Biochemical Journal
https://www.readbyqxmd.com/read/29851478/nickel-catalyzed-highly-regioselective-hydrocyanation-of-terminal-alkynes-with-zn-cn-2-using-water-as-the-hydrogen-source
#19
Xingjie Zhang, Xin Xie, Yuanhong Liu
The first efficient and general nickel-catalyzed hydrocyanation of terminal alkynes with Zn(CN)2 in the presence of water has been developed. The reaction provides a novel and regioselective protocol for the synthesis of functionalized vinyl nitriles with a wide range of structural diversity under mild reaction conditions while obviating the use of the volatile and hazardous reagent of HCN. Deuterium-labeling experiments confirmed the role of water as the hydrogen source in this hydrocyanation reaction.
May 31, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29847807/allosteric-coupling-of-carmil-and-v-1-binding-to-capping-protein-revealed-by-hydrogen-deuterium-exchange
#20
Britney Johnson, Patrick McConnell, Alex G Kozlov, Marlene Mekel, Timothy M Lohman, Michael L Gross, Gaya K Amarasinghe, John A Cooper
Actin assembly is important for cell motility. The ability of actin subunits to join or leave filaments via the barbed end is critical to actin dynamics. Capping protein (CP) binds to barbed ends to prevent subunit gain and loss and is regulated by proteins that include V-1 and CARMIL. V-1 inhibits CP by sterically blocking one binding site for actin. CARMILs bind at a distal site and decrease the affinity of CP for actin, suggested to be caused by conformational changes. We used hydrogen-deuterium exchange with mass spectrometry (HDX-MS) to probe changes in structural dynamics induced by V-1 and CARMIL binding to CP...
May 29, 2018: Cell Reports
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