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radiation chemistry

Krzysztof Bobrowski, Konrad Skotnicki, Tomasz Szreder
No abstract text is available yet for this article.
December 2016: Top Curr Chem (J)
Bugra Ayan, Adem Ozcelik, Hunter Bachman, Shi-Yang Tang, Yuliang Xie, Mengxi Wu, Peng Li, Tony Jun Huang
On-chip microparticle and cell coating technologies enable a myriad of applications in chemistry, engineering, and medicine. Current microfluidic coating technologies often rely on magnetic labeling and concurrent deflection of particles across laminar streams of chemicals. Herein, we introduce an acoustofluidic approach for microparticle and cell coating by implementing tilted-angle standing surface acoustic waves (taSSAWs) into microchannels with multiple inlets. The primary acoustic radiation force generated by the taSSAW field was exploited in order to migrate the particles across the microchannel through multiple laminar streams, which contained the buffer and coating chemicals...
October 18, 2016: Lab on a Chip
Izaskun Jiménez-Serra, Anton I Vasyunin, Paola Caselli, Nuria Marcelino, Nicolas Billot, Serena Viti, Leonardo Testi, Charlotte Vastel, Bertrand Lefloch, Rafael Bachiller
The detection of complex organic molecules (COMs) toward cold sources such as pre-stellar cores (with T<10 K), has challenged our understanding of the formation processes of COMs in the interstellar medium. Recent modelling on COM chemistry at low temperatures has provided new insight into these processes predicting that COM formation depends strongly on parameters such as visual extinction and the level of CO freeze out. We report deep observations of COMs toward two positions in the L1544 pre-stellar core: the dense, highly-extinguished continuum peak with A V ≥30 mag within the inner 2700 au; and a low-density shell with average A V ~7...
October 10, 2016: Astrophysical Journal. Letters
Daniel A Thomas, Matthew M Coggon, Hanna Lignell, Katherine Ann Schilling, Xuan Zhang, Rebecca H Schwantes, Richard C Flagan, John H Seinfeld, Jesse Lee Beauchamp
The complexation of iron (III) with oxalic acid in aqueous solution yields a strongly absorbing chromophore that undergoes efficient photodissociation to give iron (II) and the carbon dioxide anion radical. Importantly, iron (III) oxalate complexes absorb near-UV radiation (λ > 350 nm), providing a potentially powerful source of oxidants in aqueous tropospheric chemistry. Although this photochemical system has been studied extensively, the mechanistic details associated with its role in the oxidation of dissolved organic matter within aqueous aerosol remain largely unknown...
October 12, 2016: Environmental Science & Technology
M C Bacchus-Montabonel, F Calvo
Solvation effects are of major interest in the context of radiation damage, due to their potential applications in cancer therapy. Reliable modeling of the solvent is, however, quite challenging, and numerous studies have been devoted to isolated biomolecules and stepwise-hydrated molecules in which the amount of solvent is controlled one molecule at a time. The influence of stepwise hydration on radiation damage is investigated here using the example of proton-induced charge transfer in two biomolecular targets...
November 2016: Journal of Molecular Modeling
Kinga Westphal, Konrad Skotnicki, Krzysztof Bobrowski, Janusz Rak
The radiolysis of deoxygenated aqueous solution containing trimeric oligonucleotides labelled with iodinated pyrimidines and Tris-HCl as the hydroxyl radical scavenger leads to electron attachment to the halogenated bases that mainly results in single strand breaks. The iodinated trimers are 2-fold more sensitive to solvated electrons than the brominated oligonucleotides, which is explained by the barrier-free dissociation of the iodinated base anions. The present study fills the literature gap concerning the chemistry triggered by ionizing radiation in the iodinated pyrimidines incorporated into DNA...
October 4, 2016: Organic & Biomolecular Chemistry
Vivian Huynh, Zachary J Sasiene, Phillip M Mach, Teresa D Golden, Guido F Verbeck
Laser ablation has been applied to redacted documents, where the text has been concealed by other ink. This technique strips the redacting ink revealing the text that was once redacted. Once removed, a nanomanipulation technique is used to extract the ink of the underlying text where mass spectrometry is then implemented to analyze its ink chemistry. In order to facilitate microscopy with direct analyte-probed nanoextraction coupled to nanospray ionization mass spectrometry (DAPNe-NSI-MS), laser ablation must be executed prior to ink extraction...
September 2016: Science & Justice: Journal of the Forensic Science Society
Svetlana V Kilina, Patrick K Tamukong, Dmitri S Kilin
Colloidal quantum dots (QDs) are near-ideal nanomaterials for energy conversion and lighting technologies. However, their photophysics exhibits supreme sensitivity to surface passivation and defects, of which control is problematic. The role of passivating ligands in photodynamics remains questionable and is a focus of ongoing research. The optically forbidden nature of surface-associated states makes direct measurements on them challenging. Therefore, computational modeling is imperative for insights into surface passivation and its impact on light-driven processes in QDs...
October 18, 2016: Accounts of Chemical Research
Petko Chernev, Ivelina Zaharieva, Emanuele Rossini, Artur Galstyan, Holger Dau, Ernst-Walter Knapp
Structural data of the oxygen-evolving complex (OEC) in photosystem II (PSII) determined by X-ray crystallography, quantum chemistry (QC), and extended X-ray absorption fine structure (EXAFS) analyses are presently inconsistent. Therefore, a detailed study of what information can be gained about the OEC through a comparison of QC and crystallographic structure information combined with the information from range-extended EXAFS spectra was undertaken. An analysis for determining the precision of the atomic coordinates of the OEC by QC is carried out...
October 12, 2016: Journal of Physical Chemistry. B
Ekaterina S Shiryaeva, Daniil A Tyurin, Vladimir I Feldman
The X-ray-induced transformations of simple chlorofluorocarbons (CFCl3 and CF2Cl2) in solid noble-gas matrixes (Ne, Ar, Kr, and Xe) at 7 K were studied in order to elucidate basic mechanisms of the radiation-chemical degradation with possible implications for stratospheric and extraterrestrial ice chemistry. The decomposition of parent molecules and formation of products were monitored by FTIR spectroscopy, and the identification was supported by ab initio calculations at the CCSD(T) level. It was shown that the ionic reaction channels were predominating in most cases (except for CF2Cl2/Xe system)...
October 13, 2016: Journal of Physical Chemistry. A
Kai Moshammer, Ahren W Jasper, Denisia M Popolan-Vaida, Zhandong Wang, Vijai Shankar Bhavani Shankar, Lena Ruwe, Craig A Taatjes, Philippe Dagaut, Nils Hansen
This work provides new temperature-dependent mole fractions of elusive intermediates relevant to the low-temperature oxidation of dimethyl ether (DME). It extends the previous study of Moshammer et al. [ J. Phys. Chem. A 2015 , 119 , 7361 - 7374 ] in which a combination of a jet-stirred reactor and molecular beam mass spectrometry with single-photon ionization via tunable synchrotron-generated vacuum-ultraviolet radiation was used to identify (but not quantify) several highly oxygenated species. Here, temperature-dependent concentration profiles of 17 components were determined in the range of 450-1000 K and compared to up-to-date kinetic modeling results...
October 4, 2016: Journal of Physical Chemistry. A
Wolfram Feuerstein, Sebastian Höfener, Wim Klopper, Iris Lamparth, Norbert Moszner, Christopher Barner-Kowollik, Andreas-N Unterreiner
In the present study, a selection of basic substitution patterns on benzoyl(trimethyl)germane was investigated using time-dependent density-functional theory (TDDFT) to explore the influence on the stability and on the relative order of the lowest excited electronic states. The theoretical results are in agreement with absorption and fluorescence measurements. We show that electron-withdrawing groups decrease the energetic level of the lowest singlet and triplet state relative to the electron-pushing systems resulting in red-shifted radiative transitions (fluorescence)...
September 16, 2016: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
W M Grundy, D P Cruikshank, G R Gladstone, C J A Howett, T R Lauer, J R Spencer, M E Summers, M W Buie, A M Earle, K Ennico, J Wm Parker, S B Porter, K N Singer, S A Stern, A J Verbiscer, R A Beyer, R P Binzel, B J Buratti, J C Cook, C M Dalle Ore, C B Olkin, A H Parker, S Protopapa, E Quirico, K D Retherford, S J Robbins, B Schmitt, J A Stansberry, O M Umurhan, H A Weaver, L A Young, A M Zangari, V J Bray, A F Cheng, W B McKinnon, R L McNutt, J M Moore, F Nimmo, D C Reuter, P M Schenk
A unique feature of Pluto's large satellite Charon is its dark red northern polar cap. Similar colours on Pluto's surface have been attributed to tholin-like organic macromolecules produced by energetic radiation processing of hydrocarbons. The polar location on Charon implicates the temperature extremes that result from Charon's high obliquity and long seasons in the production of this material. The escape of Pluto's atmosphere provides a potential feedstock for a complex chemistry. Gas from Pluto that is transiently cold-trapped and processed at Charon's winter pole was proposed as an explanation for the dark coloration on the basis of an image of Charon's northern hemisphere, but not modelled quantitatively...
September 14, 2016: Nature
N Cohen, A Dotan, H Dodiuk, S Kenig
Superhydrophobic (SH) coatings have been shown to reduce freezing and ice nucleation rates, by means of low surface energy chemistry tailored with nano/micro roughness. Durability enhancement of SH surfaces is a crucial issue. Consequently, the present research on reducing ice adhesion is based on radiation-induced radical reaction for covalently bonding SiO2 nanoparticles to polymer coatings to obtain durable roughness. Results indicated that the proposed approach resulted in SH surfaces having high contact angles (>155°) and low sliding angles (<5°) with improved durability and transparency...
September 20, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Daniel Escudero
Photoinduced electron transfer (PET) plays relevant roles in many areas of chemistry, including charge separation processes in photovoltaics, natural and artificial photosynthesis, and photoluminescence sensors and switches. As in many other photochemical scenarios, the structural and energetic factors play relevant roles in determining the rates and efficiencies of PET and its competitive photodeactivation processes. Particularly, in the field of fluorescent sensors and switches, intramolecular PET is believed (in many cases without compelling experimental proof) to be responsible of the quench of fluorescence...
September 20, 2016: Accounts of Chemical Research
Sandeep K Malyan, Arti Bhatia, Amit Kumar, Dipak Kumar Gupta, Renu Singh, Smita S Kumar, Ritu Tomer, Om Kumar, Niveta Jain
Methane is one of the critical greenhouse gases, which absorb long wavelength radiation, affects the chemistry of atmosphere and contributes to global climate change. Rice ecosystem is one of the major anthropogenic sources of methane. The anaerobic waterlogged soil in rice field provides an ideal environment to methanogens for methanogenesis. However, the rate of methanogenesis differs according to rice cultivation regions due to a number of biological, environmental and physical factors like carbon sources, pH, Eh, temperature etc...
August 26, 2016: Science of the Total Environment
Krzysztof Bobrowski, Konrad Skotnicki, Tomasz Szreder
The most important contributions of radiation chemistry to some selected technological issues related to water-cooled reactors, reprocessing of spent nuclear fuel and high-level radioactive wastes, and fuel evolution during final radioactive waste disposal are highlighted. Chemical reactions occurring at the operating temperatures and pressures of reactors and involving primary transients and stable products from water radiolysis are presented and discussed in terms of the kinetic parameters and radiation chemical yields...
October 2016: Top Curr Chem (J)
László Wojnárovits, Erzsébet Takács
In water treatment by ionizing radiation, and also in other advanced oxidation processes, the main goal is to destroy, or at least to deactivate harmful water contaminants: pharmaceutical compounds, pesticides, surfactants, health-care products, etc. The chemical transformations are mainly initiated by hydroxyl radicals, and the reactions of the formed carbon centered radicals with dissolved oxygen basically determine the rate of oxidation. The concentration of the target compounds is generally very low as compared to the concentration of such natural 'impurities' as chloride and carbonate/bicarbonate ions or the dissolved humic substances (generally referred to as dissolved organic carbon), which consume the majority of the hydroxyl radicals...
August 2016: Top Curr Chem (J)
R M Glaeser
It has long been known that cryo-EM specimens are severely damaged by a level of electron exposure that is much lower than what is needed to obtain high-resolution images from single macromolecules. Perhaps less well appreciated in the cryo-EM literature, the vitreous ice in which samples are suspended is equally sensitivity to radiation damage. This chapter provides a review of several fundamental topics such as inelastic scattering of electrons, radiation chemistry, and radiation biology, which-together-can help one to understand why radiation damage occurs so "easily...
2016: Methods in Enzymology
Jun-Ying Wang, Jie Chen, Jiang Yang, Hao Wang, Xiu Shen, Yuan-Ming Sun, Meili Guo, Xiao-Dong Zhang
Gold nanoclusters (Au NCs) have exhibited great advantages in medical diagnostics and therapies due to their efficient renal clearance and high tumor uptake. The in vivo effects of the surface chemistry of Au NCs are important for the development of both nanobiological interfaces and potential clinical contrast reagents, but these properties are yet to be fully investigated. In this study, we prepared glutathione-protected Au NCs of a similar hydrodynamic size but with three different surface charges: positive, negative, and neutral...
2016: International Journal of Nanomedicine
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