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Proton and carbon

Chi-Yuan Lee, Shih-Chun Li, Chia-Hung Chen, Yen-Ting Huang, Yu-Syuan Wang
Looking for alternative energy sources has been an inevitable trend since the oil crisis, and close attentioned has been paid to hydrogen energy. The proton exchange membrane (PEM) water electrolyzer is characterized by high energy efficiency, high yield, simple system and low operating temperature. The electrolyzer generates hydrogen from water free of any carbon sources (provided the electrons come from renewable sources such as solar and wind), so it is very clean and completely satisfies the environmental requirement...
March 15, 2018: Sensors
J H Bin, M Yeung, Z Gong, H Y Wang, C Kreuzer, M L Zhou, M J V Streeter, P S Foster, S Cousens, B Dromey, J Meyer-Ter-Vehn, M Zepf, J Schreiber
We report on the experimental studies of laser driven ion acceleration from a double-layer target where a near-critical density target with a few-micron thickness is coated in front of a nanometer-thin diamondlike carbon foil. A significant enhancement of proton maximum energies from 12 to ∼30  MeV is observed when a relativistic laser pulse impinges on the double-layer target under linear polarization. We attributed the enhanced acceleration to superponderomotive electrons that were simultaneously measured in the experiments with energies far beyond the free-electron ponderomotive limit...
February 16, 2018: Physical Review Letters
Yun Cao, Zhigang Geng, Weiwei Chen, Fan Cai, Guoxiong Wang, Zhengfei Wang, Jie Zeng
Introducing C-B diatomic groups in carbon-doped hexagonal boron nitride (h-BN) flakes resulted in high activity and selectivity for HCOOH in CO2 electroreduction. The activation of CO2 was prone to occur on B atoms while the activation of the proton occurred on C atoms. The volcano-type relation of Faradaic efficiency for HCOOH production over carbon content originates from the balance of H* and COOH* intermediates in carbon-doped h-BN catalysts.
March 15, 2018: Chemical Communications: Chem Comm
Sopheavy Siek, Dalton B Burks, Deidra L Gerlach, Guangchao Liang, Jamie M Tesh, Courtney R Thompson, Fengrui Qu, Jennifer E Shankwitz, Robert M Vasquez, Nicole Chambers, Gregory J Szulczewski, Douglas B Grotjahn, Charles Edwin Webster, Elizabeth T Papish
Hydrogenation reactions can be used to store energy in chemical bonds, and if these reactions are reversible, that energy can be released on demand. Some of the most effective transition metal catalysts for CO2 hydrogenation have featured pyridin-2-ol-based ligands (e.g., 6,6'-dihydroxybipyridine (6,6'-dhbp)) for both their proton-responsive features and for metal-ligand bifunctional catalysis. We aimed to compare bidentate pyridin-2-ol based ligands with a new scaffold featuring an N -heterocyclic carbene (NHC) bound to pyridin-2-ol...
March 27, 2017: Organometallics
Katsuaki Kobayashi, Take-Aki Koizumi, Debashis Ghosh, Takashi Kajiwara, Susumu Kitagawa, Koji Tanaka
A RhCp* (Cp* = pentamethylcyclopentadienyl) complex bearing an NAD+ /NADH-functionalized ligand, [RhCp*(pbn)Cl]Cl ([1]Cl, pbn = (2-(2-pyridyl)benzo[b]-1,5-naphthyridine)), was synthesized. The cyclic voltammogram of [1]Cl in CH3 CN shows two reversible redox waves at E1/2 = -0.58 and -1.53 V (vs. the saturated calomel electrode (SCE)), which correspond to the RhIII /RhI and pbn/pbn˙- redox couples, respectively. The addition of acetic acid to the solution afforded the proton-coupled two-electron reduction of [1]Cl at -0...
March 14, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Andrea Angeli, Fatmah A S Alasmary, Sonia Del Prete, Sameh M Osman, Zeid AlOthman, William A Donald, Clemente Capasso, Claudiu T Supuran
The activation of the δ-class carbonic anhydrase (CAs, EC from the diatom Thalassiosira weissflogii (TweCAδ) was investigated using a panel of natural and non-natural amino acids and amines. The most effective activator of TweCAδ was d-Tyr (KA of 51 nM), whereas several other amino acids and amines, such as L-His, L-Trp, d-Trp, dopamine and serotonin were submicromolar activators (KA s from 0.51 to 0.93 µM). The most ineffective activator of TweCAδ was 4-amino-l-Phe (18.9 µM), whereas d-His, l-/d-Phe, l-/d-DOPA, l-Tyr, histamine, some pyridyl-alkylamines, l-adrenaline and aminoethyl-piperazine/morpholine were moderately potent activators (KA s from 1...
December 2018: Journal of Enzyme Inhibition and Medicinal Chemistry
Yuchen Yang, Wuxia Guo, Xu Shen, Jianfang Li, Shuhuan Yang, Sufang Chen, Ziwen He, Renchao Zhou, Suhua Shi
Alternative splicing (AS), which produces multiple mRNA transcripts from a single gene, plays crucial roles in plant growth, development and environmental stress responses. Functional significances of conserved AS events among congeneric species have not been well characterized. In this study, we performed transcriptome sequencing to characterize AS events in four common species of Sonneratia, a mangrove genus excellently adaptive to intertidal zones. 7,248 to 12,623 AS events were identified in approximately 25% to 35% expressed genes in the roots of the four species...
March 13, 2018: Scientific Reports
F Meyer, M Blum, A Benkert, D Hauschild, Y L Jeyachandran, R G Wilks, W Yang, M Bär, F Reinert, C Heske, M Zharnikov, L Weinhardt
The occupied and unoccupied electronic structure of imidazole (C3 N2 H4 ) and imidazolium (C3 N2 H5 + ) in aqueous solutions is studied by X-ray emission spectroscopy (XES) and resonant inelastic soft X-ray scattering (RIXS). Both systems show distinct RIXS fingerprints with strong resonant effects. A comparison with calculated X-ray emission spectra of isolated imidazole and imidazolium suggests only a small influence of hydrogen bonding in the aqueous solution on the electronic structure of imidazole and imidazolium, and allows the attribution of specific spectral features to the non-equivalent nitrogen and carbon atoms in the molecules...
March 13, 2018: Physical Chemistry Chemical Physics: PCCP
Josep Saurí, Wolfgang Bermel, Teodor Parella, R Thomas Williamson, Gary E Martin
1,n-ADEQUATE is a powerful NMR technique for elucidating the structure of proton-deficient small molecules that can help to establish the carbon skeleton of a given molecule by providing long-range three-bond13 C-13 C correlations. Care must be taken when using the experiment to identify the simultaneous presence of one-bond13 C-13 C correlations that are not filtered out, unlike the HMBC experiment that has a low-pass J-filter to filter1 JCH responses out. Dual-optimized, inverted1 JCC 1,n-ADEQUATE is an improved variant of the experiment that affords broadband inversion of direct responses, obviating the need to take additional steps to identify these correlations...
March 13, 2018: Magnetic Resonance in Chemistry: MRC
Felipe Fantuzzi, Benedikt Rudek, Wania Wolff, Marco Antonio Chaer Nascimento
In free-radical halogenation of aromatics singly-charged ions are usually formed as intermediates. These stable species can be easily observed by time-of-flight mass spectrometry (TOF-MS). Here we used electron and proton beams to ionize chlorobenzene (C6 H5Cl) and investigate the ions stability by TOF-MS. Additionally to the singly-charged parent ion and its fragments we find a significant yield of doubly- and triply- charged parentions not previously reported. In order to characterize these species we used high-level theoretical methods based on Density Functional Theory (DFT), Coupled-Cluster (CC)and Generalized Valence Bond (GVB) to calculate the structure, relative stabilities, and bonding of these dications and trications...
March 12, 2018: Journal of the American Chemical Society
Anussara Prayongrat, Kikuo Umegaki, Arjen van der Schaaf, Albert C Koong, Steven H Lin, Thomas Whitaker, Todd McNutt, Naruhiro Matsufuji, Edward Graves, Masahiko Mizuta, Kazuhiko Ogawa, Hiroyuki Date, Kensuke Moriwaki, Yoichi M Ito, Keiji Kobashi, Yasuhiro Dekura, Shinichi Shimizu, Hiroki Shirato
Particle beam therapy (PBT), including proton and carbon ion therapy, is an emerging innovative treatment for cancer patients. Due to the high cost of and limited access to treatment, meticulous selection of patients who would benefit most from PBT, when compared with standard X-ray therapy (XRT), is necessary. Due to the cost and labor involved in randomized controlled trials, the model-based approach (MBA) is used as an alternative means of establishing scientific evidence in medicine, and it can be improved continuously...
February 24, 2018: Journal of Radiation Research
Mathias Hermann, Daniel Wassy, Daniel Kratzert, Birgit Esser
In cyclophanes an aromatic moiety is incorporated into a (strained) cyclic structure. Of particular interest as model systems for bent carbon nanostructures are those containing polycyclic aromatic hydrocarbons. Dibenzo[a,e]pentalene (DBP) is a non-alternant polycyclic hydrocarbon with small bandgap and tunable optoelectronic properties. However, changing these properties by bending of the DBP structure have yet to be investigated. Herein, we report the synthesis, optoelectronic and structural properties of (2,7)dibenzo[a,e]pentalenophanes with four different bridge sizes and bending angles of the DBP unit, accompanied by (TD)DFT calculations...
March 12, 2018: Chemistry: a European Journal
Ricarda Höhner, Joaquim V Marques, Tetsuro Ito, Yoshiaki Amakura, Alan D Budgeon, Karl Weitz, Kim K Hixson, Laurence B Davin, Helmut Kirchhoff, Norman G Lewis
Arogenate dehydratase (ADT) catalyzes the final step of phenylalanine (Phe) biosynthesis. Previous work showed that ADT-deficient Arabidopsis thaliana mutants had significantly reduced lignin contents, with stronger reductions in lines that had deficiencies in more ADT isoforms. Here, by analyzing Arabidopsis ADT mutants using our phenomics facility and UPLC-MS based metabolomics, we describe the effects of modulation of ADT on photosynthetic parameters and secondary metabolism. Our data indicate that a reduced carbon flux into Phe biosynthesis in ADT mutants impairs the consumption of photosynthetically produced ATP leading to an increased ATP/ADP ratio, the over-accumulation of transitory starch, and lower electron transport rates...
March 9, 2018: Plant Physiology
Kashif Mairaj Deen, Edouard Asselin
The development of a hybrid system, capable of storing energy, and with the additional benefit of Cu extraction is discussed in this work. A fixed bed flow cell (FBFC) was used in which a composite negative electrode containing CuFeS2 (80 wt. %) and carbon black (20 wt. %) in graphite felt was separated from a positive (graphite felt) electrode by proton exchange membrane. The anolyte (0.2M H2SO4) and catholyte (0.5M Fe2+ in 0.2M H2SO4 with or without 0.1M Cu2+ addition) were circulated in the cell. With the addition of Cu2+ in the catholyte, the electrochemical activity of the Fe2+/Fe3+ redox couple over graphite felt was significantly improved...
March 8, 2018: ChemSusChem
Hiroki Shirato
No abstract text is available yet for this article.
March 8, 2018: International Journal of Clinical Oncology
Christine C Helms, Mark T Gladwin, Daniel B Kim-Shapiro
Erythrocytes regulate vascular function through the modulation of oxygen delivery and the scavenging and generation of nitric oxide (NO). First, hemoglobin inside the red blood cell binds oxygen in the lungs and delivers it to tissues throughout the body in an allosterically regulated process, modulated by oxygen, carbon dioxide and proton concentrations. The vasculature responds to low oxygen tensions through vasodilation, further recruiting blood flow and oxygen carrying erythrocytes. Research has shown multiple mechanisms are at play in this classical hypoxic vasodilatory response, with a potential role of red cell derived vasodilatory molecules, such as nitrite derived nitric oxide and red blood cell ATP, considered in the last 20 years...
2018: Frontiers in Physiology
Paul R Rablen, Nathalie Abigail Perry-Freer
G-4 calculations are used to explore which carbon atoms of methylated butadienes, methylated cyclopentadienes, and methylated benzenes are most readily protonated to yield delocalized allyl and pentadienyl cations. While it is not surprising that alkylation of the positions bearing formal positive charge stabilizes these cations, several other effects are less obvious. First, alkylation of positions in the delocalized cation that do not bear formal charge is beneficial, to an extent about a quarter to a third as great as at charged positions...
March 8, 2018: Journal of Organic Chemistry
Wencheng Shao, Xiaobin Tang, Yanling Bai, Diyun Shu, Changran Geng, Chunhui Gong, Fada Guan
Background: Magnetic resonance imaging (MRI)-guided radiotherapy is a promising image-guided cancer radiotherapy method. For MRI-guided radiotherapy, the proper energy of a therapeutic beam is important for beam-designing processes, and the magnetic-induced dose perturbation would be mainly influenced, especially the perturbation surrounding the tissue-air or air-tissue interfaces. Thus, it was necessary to investigate the impact of beam energy from photon, proton, and carbon ion beams on the magnetic-induced dose perturbations...
January 2018: Journal of Cancer Research and Therapeutics
Ming Xiao, Wei Chen, Weiyao Li, Jiuzhou Zhao, You-Lee Hong, Yusuke Nishiyama, Toshikazu Miyoshi, Matthew D Shawkey, Ali Dhinojwala
Eumelanin is one of the most ubiquitous pigments in living organisms and plays an important role in coloration and UV protection. Because eumelanin is highly cross-linked and insoluble in solvents, the chemical structure is still not completely known. In this study, we used atomic force microscopy, X-ray photoelectron spectroscopy and solid-state nuclear magnetic resonance (NMR) to compare intact eumelanosomes (pigment granules mostly made of eumelanin) from four phylogentically distant species: cuttlefish ( Sepia officinalis ) inks, black fish crow ( Corvus ossifragus ) feathers, iridescent wild turkey ( Melleagris gallopavo ) feathers and black human hair...
March 2018: Journal of the Royal Society, Interface
Liliana Stolarczyk, Sebastian Trinkl, Maite Romero-Exposito, Natalia Mojżeszek, Iva Ambrozova, Carles Domingo, Marie Davidkova, Jad Farah, Magdalena Kłodowska, Željka Knežević, Małgorzata Liszka, Marija Majer, Saveta Miljanic, Ondrej Ploc, Marco Schwarz, Roger Michael Harrison, Pawel Olko
Systematic 3-D mapping of out-of-field doses induced by a therapeutic proton pencil scanning beam (PBS) in a 300 × 300 × 600 mm3 water phantom was performed using a set of thermoluminescence detectors (TLD): MTS-7 (<sup>7</sup>LiF:Mg,Ti), MTS-6 (<sup>6</sup>LiF:Mg,Ti), MTS-N (<sup>nat</sup>LiF:Mg,Ti) and TLD-700 (<sup>7</sup>LiF:Mg,Ti), radiophotoluminescent detectors (RPL) GD-352M and GD-302M and polyallyldiglycol carbonate (PADC)-based (C<sub>12</sub>H<sub>18</sub>O<sub>7</sub>) track-etched detectors...
March 6, 2018: Physics in Medicine and Biology
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