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https://www.readbyqxmd.com/read/28936278/modulating-the-catalytic-activity-of-cerium-oxide-nanoparticles-with-the-anion-of-the-precursor-salt
#1
Swetha Barkam, Julian Ortiz, Shashank Saraf, Nicholas Eliason, Rameech Mccormack, Soumen Das, Ankur Gupta, Craig Neal, Alex Petrovici, Cameron Hanson, Michael D Sevilla, Amitava Adhikary, Sudipta Seal
In this work, we tested our hypothesis that surface chemistry and antioxidant properties of cerium nanoparticles (CNPs) are affected by presence of counterions. We first employed various precursor cerium (III) (Ce(III)) salts with different counterions (acetate, nitrate, chloride, sulfate) to synthesize CNPs following the same wet chemical methodology. Electron spin resonance (ESR) studies provided evidence for the formation of radicals from counterions (e.g., NO3•(2-) from reduction of NO3(-) in CNPs synthesized from Ce(III) nitrate)...
September 14, 2017: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
https://www.readbyqxmd.com/read/28910515/chiral-kagome-lattices-from-on-surface-synthesized-molecules
#2
Tao Wang, Qitang Fan, Lin Feng, Zhijie Tao, Jianmin Huang, Huanxin Ju, Qian Xu, Shanwei Hu, Junfa Zhu
Kagome lattices have attracted much attention due to their potential applications in spin-frustrated magnetism and host-guest chemistry. Examples toward the fabrication of 2D Kagome lattices reported previously have a common feature that the precursor molecules were typically structurally intact on surface with no chemical reactions accompanied. Herein, with the combined synchrotron radiation photoelectron spectroscopy (SRPES) and scanning tunneling microscopy (STM), we demonstrated that two types of chiral Kagome lattices from on-surface synthesized organometallic compounds were fabricated, which are known as intermediates of Glaser coupling on silver single crystal surfaces...
September 14, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28905949/electronic-and-molecular-structure-relations-in-diiron-compounds-mimicking-the-fefe-hydrogenase-active-site-studied-by-x-ray-spectroscopy-and-quantum-chemistry
#3
Ramona Kositzki, Stefan Mebs, Nils Schuth, Nils Leidel, Lennart Schwartz, Michael Karnahl, Florian Wittkamp, Daniel Daunke, Andreas Grohmann, Ulf-Peter Apfel, Frédéric Gloaguen, Sascha Ott, Michael Haumann
Synthetic diiron compounds of the general formula Fe2(μ-S2R)(CO)n(L)6-n (R = alkyl or aromatic groups; L = CN(-) or phosphines) are versatile models for the active-site cofactor of hydrogen turnover in [FeFe]-hydrogenases. A series of 18 diiron compounds, containing mostly a dithiolate bridge and terminal ligands of increasing complexity, was characterized by X-ray absorption and emission spectroscopy in combination with density functional theory. Fe K-edge absorption and Kβ main-line emission spectra revealed the varying geometry and the low-spin state of the Fe(i) centers...
September 14, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28901132/regioselectivity-of-the-oh-radical-addition-to-uracil-in-nucleic-acids-a-theoretical-approach-based-on-qm-mm-simulations
#4
Juan Aranda, Antonio Francés-Monerris, Iñaki Tuñón, Daniel Roca-Sanjuán
Oxidation of nucleic acids are ubiquitous in living beings under metabolic impairments and/or exposed to external agents such as radiation, pollutants, or drugs, playing a central role in the development of many diseases mediated by DNA/RNA degeneration. Great efforts have been devoted to unveil the molecular mechanisms behind the OH radical additions to the double bonds of nucleobases, however, the specific role of the biological environment remains rela-tively unexplored. The present contribution tackles the study of the OH radical addition to uracil from the gas phase to a full RNA macromolecule by means of quantum-chemistry methods combined with molecular dynamics simulations...
September 13, 2017: Journal of Chemical Theory and Computation
https://www.readbyqxmd.com/read/28895676/maria-sk%C3%A5-odowska-curie-her-life-and-work-the-150-anniversary-of-her-birthday
#5
Małgorzata M. Dobrzyńska
Maria Skłodowska was born on November 7, 1867 in Warsaw (Poland). Her parents were teachers. Maria’s mother has died in 1878 of tuberculosis. In 1893 and 1894, respectively, Maria was awarded master’s degrees in physics and in mathematics from the Sorbonne University. In 1895 Maria married Pierre Curie. In 1897 their daughter Irene was born. Maria investigated rays emitted by uranium salts. She hypothesized that the radiation come from atom and called this phenomenon “radioactivity”. In 1898, Maria and Pierre discovered new radioactive elements polonium and radium...
2017: Roczniki Państwowego Zakładu Higieny
https://www.readbyqxmd.com/read/28886187/evaluating-the-role-of-land-cover-and-climate-uncertainties-in-computing-gross-primary-production-in-hawaiian-island-ecosystems
#6
Heather L Kimball, Paul C Selmants, Alvaro Moreno, Steve W Running, Christian P Giardina
Gross primary production (GPP) is the Earth's largest carbon flux into the terrestrial biosphere and plays a critical role in regulating atmospheric chemistry and global climate. The Moderate Resolution Imaging Spectrometer (MODIS)-MOD17 data product is a widely used remote sensing-based model that provides global estimates of spatiotemporal trends in GPP. When the MOD17 algorithm is applied to regional scale heterogeneous landscapes, input data from coarse resolution land cover and climate products may increase uncertainty in GPP estimates, especially in high productivity tropical ecosystems...
2017: PloS One
https://www.readbyqxmd.com/read/28874585/active-molecular-iodine-photochemistry-in-the-arctic
#7
Angela R W Raso, Kyle D Custard, Nathaniel W May, David Tanner, Matt K Newburn, Lawrence Walker, Ronald J Moore, L G Huey, Liz Alexander, Paul B Shepson, Kerri A Pratt
During springtime, the Arctic atmospheric boundary layer undergoes frequent rapid depletions in ozone and gaseous elemental mercury due to reactions with halogen atoms, influencing atmospheric composition and pollutant fate. Although bromine chemistry has been shown to initiate ozone depletion events, and it has long been hypothesized that iodine chemistry may contribute, no previous measurements of molecular iodine (I2) have been reported in the Arctic. Iodine chemistry also contributes to atmospheric new particle formation and therefore cloud properties and radiative forcing...
September 5, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28871437/free-radical-studies-of-components-of-the-extracellular-matrix-contributions-to-protection-of-biomolecules-and-biomaterials-from-sterilising-doses-of-ionising-radiation
#8
Barry J Parsons
The purpose of the current review is show how the principles and techniques of radiation chemistry have enabled the direct reactions of free radicals with biomolecules and biomaterials to be investigated at the molecular level. In particular, the review focusses on the free radical-induced fragmentation of glycosaminoglycans. Glycosaminoglycans are large linear polysaccharides consisting of repeating disaccharide units and are important components of the extracellular matrix (ECM) either in free form (hyaluronan) or as a component of proteoglycans...
September 4, 2017: Cell and Tissue Banking
https://www.readbyqxmd.com/read/28857102/theoretical-investigation-on-spin-forbidden-cooling-transitions-of-gallium-hydride
#9
Yun-Guang Zhang, Hua Zhang, Hai-Yang Song, You Yu, Ming-Jie Wan
Herein, the spin-forbidden cooling of a gallium hydride molecule is investigated using ab initio quantum chemistry. The cooling transition and the corresponding potential energy curves including , a(3)Π0(-), a(3)Π0(+), a(3)Π1, a(3)Π2, A(1)Π1, , 1(3)Σ, , , and 2(3)Σ states are simulated based on the multi-reference configuration interaction approach plus Davidson corrections method. By solving the nuclear Schrödinger equation, we calculate the spectroscopic constants of these states, which are in good agreement with the available experimental values...
September 20, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28851657/computer-simulation-and-experimental-self-assembly-of-irradiated-glycine-amino-acid-under-magnetic-fields-its-possible-significance-in-prebiotic-chemistry
#10
Alejandro Heredia, María Colín-García, Teresa Pi I Puig, Leticia Alba-Aldave, Adriana Meléndez, Jorge A Cruz-Castañeda, Vladimir A Basiuk, Sergio Ramos-Bernal, Alicia Negrón Mendoza
Ionizing radiation may have played a relevant role in chemical reactions for prebiotic biomolecule formation on ancient Earth. Environmental conditions such as the presence of water and magnetic fields were possibly relevant in the formation of organic compounds such as amino acids. ATR-FTIR, Raman, EPR and X-ray spectroscopies provide valuable information about molecular organization of different glycine polymorphs under static magnetic fields. γ-glycine polymorph formation increases in irradiated samples interacting with static magnetic fields...
August 26, 2017: Bio Systems
https://www.readbyqxmd.com/read/28846846/excess-electron-and-hole-in-1-benzylpyridinium-based-ionic-liquids
#11
Kamal B Dhungana, Fei Wu, Claudio J Margulis
The study of ionic liquids that may be compatible with the type of radiation chemistry events occurring in nuclear separation processes is a topic of high current interest. In this article, we focus on two ionic liquids based on the benzylpyridinium cation. This cation has been proposed to be able to capture either an excess electron or hole without undergoing fast dissociation. Shkrob, Wishart, and collaborators ( J. Phys. Chem. B 2013 , 117 ( 46 ), 14385 - -14399 ) have indicated that the stabilization is likely in the form of dimers in solution with the excess electron localized on adjacent pyridinium rings and the excess hole localized on phenyl rings...
September 11, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28832142/study-of-the-synchrotron-photoionization-oxidation-of-2-methylfuran-initiated-by-o-3-p-under-low-temperature-conditions-at-550-and-650-k
#12
Yasmin Fathi, Giovanni Meloni
The O((3)P)-initiated oxidation of 2-methylfuran (2-MF) was investigated using vacuum-ultraviolet synchrotron radiation from the Advanced Light Source at Lawrence Berkeley National Laboratory. Reaction species were studied by multiplexed photoionization mass spectrometry at 550 and 650 K. The oxygen addition pathway is favored in this reaction, forming four triplet diradicals that undergo intersystem crossing into singlet epoxide species that lead to the formation of products at m/z 30 (formaldehyde), 42 (propene), 54 (1-butyne, 1,3-butadiene, and 2-butyne), and 70 (2-butenal, methyl vinyl ketone, and 3-butenal)...
September 12, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28819268/heterogenous-oceanic-redox-conditions-through-the-ediacaran-cambrian-boundary-limited-the-metazoan-zonation
#13
Junpeng Zhang, Tailiang Fan, Yuandong Zhang, Gary G Lash, Yifan Li, Yue Wu
Recent studies have enhanced our understanding of the linkage of oxygenation and metazoan evolution in Early Cambrian time. However, little of this work has addressed the apparent lag of animal diversification and atmospheric oxygenation during this critical period of Earth history. This study utilizes the geochemical proxy and N isotope record of the Ediacaran-Cambrian boundary preserved in intra-shelf basin, slope, and slope basin deposits of the Yangtze Sea to assess the ocean redox state during the Early Cambrian metazoan radiation...
August 17, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28796511/unveiling-the-ionization-energy-of-the-cn-radical
#14
Bérenger Gans, Séverine Boyé-Péronne, Gustavo A Garcia, Anja Röder, Domenik Schleier, Philippe Halvick, Jean-Christophe Loison
The cyano radical is a ubiquitous molecule and was, for instance, one of the first species detected in astrophysical media such as comets or diffuse clouds. In photodissociation regions, the reaction rate of CN(+) + CO → CN + CO(+) is one of the critical parameters defining nitrile chemistry. The enthalpy of this charge transfer reaction is defined as the difference of ionization energies (EI) between CN and CO. Although EI(CO) is known accurately, the EI(CN) values are more dispersed and deduced indirectly from thermodynamic thresholds only, all above EI(CO), leading to the assumption that the reaction is fast even at low temperature...
August 15, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28782644/dmapt-inhibits-nf-%C3%AE%C2%BAb-activity-and-increases-sensitivity-of-prostate-cancer-cells-to-x-rays-in-vitro-and-in-tumor-xenografts-in-vivo
#15
Marc S Mendonca, William T Turchan, Melanie E Alpuche, Christopher N Watson, Neil C Estabrook, Helen Chin-Sinex, Jeremy B Shapiro, Imade E Imasuen-Williams, Gabriel Rangel, David P Gilley, Nazmul Huda, Peter A Crooks, Ronald H Shapiro
Constitutive activation of the pro-survival transcription factor NF-κB has been associated with resistance to both chemotherapy and radiation therapy in many human cancers, including prostate cancer. Our lab and others have demonstrated that the natural product parthenolide can inhibit NF-κB activity and sensitize PC-3 prostate cancers cells to X-rays in vitro; however, parthenolide has poor bioavailability in vivo and therefore has little clinical utility in this regard. We show here that treatment of PC-3 and DU145 human prostate cancer cells with dimethylaminoparthenolide (DMAPT), a parthenolide derivative with increased bioavailability, inhibits constitutive and radiation-induced NF-κB binding activity and slows prostate cancer cell growth...
August 3, 2017: Free Radical Biology & Medicine
https://www.readbyqxmd.com/read/28780689/can-radiation-chemistry-supply-a-highly-efficient-ao-r-p-process-for-organics-removal-from-drinking-and-waste-water-a-review
#16
Marek Trojanowicz, Anna Bojanowska-Czajka, Andrea G Capodaglio
The increasing role of chemistry in industrial production and its direct and indirect impacts in everyday life create the need for continuous search and efficiency improvement of new methods for decomposition/removal of different classes of waterborne anthropogenic pollutants. This review paper addresses a highly promising class of water treatment solutions, aimed at tackling the pressing problem of emerging contaminants in natural and drinking waters and wastewater discharges. Radiation processing, a technology originating from radiation chemistry studies, has shown encouraging results in the treatment of (mainly) organic water pollution...
August 5, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28764119/trans-pacific-transport-of-dust-aerosols-from-east-asia-insights-gained-from-multiple-observations-and-modeling
#17
Jianping Guo, Mengyun Lou, Yucong Miao, Yuan Wang, Zhaoliang Zeng, Huan Liu, Jing He, Hui Xu, Fu Wang, Min Min, Panmao Zhai
East Asia is one of the world's largest sources of dust and anthropogenic pollution. Dust particles originating from East Asia have been recognized to travel across the Pacific to North America and beyond, thereby affecting the radiation incident on the surface as well as clouds aloft in the atmosphere. In this study, integrated analyses are performed focusing on one trans-Pacific dust episode during 12-22 March 2015, based on space-borne, ground-based observations, reanalysis data combined with Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT), and the Weather Research and Forecasting Model coupled with Chemistry (WRF-Chem)...
November 2017: Environmental Pollution
https://www.readbyqxmd.com/read/28759726/inorganic-nanoparticles-as-donors-in-resonance-energy-transfer-for-solid-phase-bioassays-and-biosensors
#18
Yi Han, M Omair Noor, Abootaleb Sedighi, Uvaraj Uddayasankar, Samer Doughan, Ulrich J Krull
Bioassays for the rapid detection and quantification of specific nucleic acids, proteins, and peptides are fundamental tools in many clinical settings. Traditional optical emission methods have focused on the use of molecular dyes as labels to track selective binding interactions and as probes that are sensitive to environmental changes. Such dyes can offer good detection limits based on brightness but typically have broad emission bands and suffer from time-dependent photobleaching. Inorganic nanoparticles such as quantum dots and upconversion nanoparticles are photostable over prolonged exposure to excitation radiation and tend to offer narrow emission bands, providing a greater opportunity for multiwavelength multiplexing...
August 11, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28759069/the-mechanism-for-the-formation-of-oh-radicals-in-condensed-phase-water-under-ultraviolet-irradiation
#19
Fan Jin, Min Wei, Chengbu Liu, Yuchen Ma
Irradiation on liquid water and ice by ultraviolet light in the range of 150-200 nm can create volatile OH radicals which react with other organic and inorganic molecules actively. However, the mechanism for OH radical formation in the condensed-phase water in this energy range is still unclear. To uncover this mechanism we studied the excited-state behaviors of ice using first-principles calculations based on many-body Green's function theory. First, we showed that the long-wavelength optical absorption at the Urbach tail (190-300 nm) can be attributed to inherent hydroxide ions or transient structures formed in the autoionization process...
August 16, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28731691/singlet-oxygen-photophysics-in-liquid-solvents-converging-on-a-unified-picture
#20
Mikkel Bregnhøj, Michael Westberg, Boris F Minaev, Peter R Ogilby
Singlet oxygen, O2(a(1)Δg), the lowest excited electronic state of molecular oxygen, is an omnipresent part of life on earth. It is readily formed through a variety of chemical and photochemical processes, and its unique reactions are important not just as a tool in chemical syntheses but also in processes that range from polymer degradation to signaling in biological cells. For these reasons, O2(a(1)Δg) has been the subject of intense activity in a broad distribution of scientific fields for the past ∼50 years...
July 21, 2017: Accounts of Chemical Research
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