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Spectroscopy

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https://www.readbyqxmd.com/read/28346903/the-oceanus-statue-of-the-fontana-di-trevi-rome-the-analysis-of-black-crust-as-a-tool-to-investigate-the-urban-air-pollution-and-its-impact-on-the-stone-degradation
#1
Mauro F La Russa, Paola Fermo, Valeria Comite, Cristina M Belfiore, Donatella Barca, Annamaria Cerioni, Marina De Santis, Lorena Francesca Barbagallo, Michela Ricca, Silvestro A Ruffolo
This paper deals with the analysis of black crust coming from the statue of Oceanus belonging to the Fontana di Trevi (Rome). This monument is undoubtedly one of the main touristic attractions of Rome. During the restoration held between 2014 and 2015, some diagnostic analyses had been carried out. It has been highlighted that the sheltered surfaces suffer the formation of black crust, especially on the marble statues. The possibility to sample those degradation products, together with the unaltered substrate, represented an excellent opportunity to characterize the marble itself, to assess the impact of the urban air pollution on the stone material, and to detect the pollutant on a precise timescale...
March 24, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28346785/infrared-spectroscopy-of-ionic-liquids-consisting-of-imidazolium-cations-with-different-alkyl-chain-lengths-and-various-halogen-or-molecular-anions-with-and-without-a-small-amount-of-water
#2
Toshiki Yamada, Yukihiro Tominari, Shukichi Tanaka, Maya Mizuno
Infrared spectroscopy was performed on ionic liquids (ILs) that had imidazolium cations with different alkyl chain lengths and various halogen or molecular anions with and without a small amount of water. The molar concentration normalized absorbance due to +C-H vibrational modes in the range of 3000 to 3200 cm-1 was nearly identical for ILs that had imidazolium cations with different alkyl chain lengths and the same anions. A close correlation was found between the red-shifted +C-H vibrational modes, the chemical shift of +C(2)-H proton, and the energy stabilization of hydrogen-bonding interaction...
March 27, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28346783/dicarbonyls-of-carbon-and-methylidyne-cations
#3
Jiaye Jin, Lili Zhao, Xiaonan Wu, Wei Li, Yuhong Liu, Diego M Andrada, Mingfei Zhou, Gernot Frenking
The carbon suboxide cation C3O2+ and the protonated carbon suboxide HC3O2+/DC3O2+ were produced in the gas phase. The vibrational spectra were measured via infrared photodissociation spectroscopy of their argon- or CO-tagged complexes. Spectroscopic evidence combined with state-of-the-art quantum chemical calculations indicate that both cations have a bent C2v symmetry and can be designated as dicarbonyls of carbon cation and methylidyne cation, respectively.
March 27, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28346780/high-spin-polymers-ferromagnetic-coupling-of-s-1-hexaazacyclophane-units-up-to-a-pure-s-2-polycyclophane
#4
Lukasz Skorka, Piotr Kurzep, Timothée Chauviré, Lionel Dubois, Jean-Marie Mouesca, Vincent Maurel, Irena Kulszewicz-Bajer
Triarylamines oxidized to radical cations can be used as stable spins sources for the design of high-spin compounds. Here, we present the synthesis of the polyarylamine containing hexaazacyclophanes linked via meta-terphenyl bridges. Spins, created after the oxidation of the polymer, can be coupled magnetically in cyclophane moieties via meta-phenyl and along the polymer chain via meta-terphenyl units. The formation of quintet spin state was evidenced by pulsed-EPR nutation spectroscopy. Two exchange coupling constants via both couplers were determined experimentally and corresponded to J/k = 89 K in cyclophane moiety and j/k = 17 K via meta-terphenyl...
March 27, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28346778/direct-measurement-of-the-angular-pair-correlations-coefficients-in-molecular-liquids-using-nmr-benchmarking-force-fields-for-atomistic-simulations
#5
Leah Marie Heist, Chi-Duen Poon, Edward Thaddeus Samulski, Demetri J Photinos
High field deuterium NMR spectroscopy is used to characterize a number of molecular liquids and their mixtures in order to probe the directional part of the intermolecular interactions through the orientational ordering induced in the isotropic liquid phase by the spectrometer magnetic field. The systems studied include benzene, chloroform, hexafluorobenzene and thiophene at various concentrations and in mixtures. Dilution with the magnetically isotropic tetramethylsilane provides quantification of ordering at "infinite magnetic dilution", i...
March 27, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28346552/incorporation-of-vanadium-into-the-framework-of-hydroxyapatites-importance-of-the-vanadium-content-and-ph-conditions-during-the-precipitation-step
#6
Sarah Petit, Thrimurthulu Gode, Cyril Thomas, Stanislaw Dzwigaj, Yannick Millot, Dalil Brouri, Jean-Marc Krafft, Gwenaelle Rousse, Christel Laberty-Robert, Guylène Costentin
Even though vanadium-modified hydroxyapatite (V-HAp) samples are very promising systems for oxidative dehydrogenation of propane, the incorporation of vanadium into the hydroxyapatite framework was reported to be limited and to lead to over-stoichiometric compounds. Here, the synthesis of a Ca10(PO4)6-x(VO4)x(OH)2 stoichiometric solid solution using a co-precipitation method is monitored in the whole composition range (0 ≤ x ≤ 6) by controlling the pH of the precipitation medium, with continuous (the first series of samples) or periodic (the second series of samples) addition of NH4OH during the precipitation step or during the maturation step, respectively...
March 27, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28346471/effect-of-functional-sympathetic-nervous-system-impairment-of-the-liver-and-abdominal-visceral-adipose-tissue-on-circulating-triglyceride-rich-lipoproteins
#7
Michael F La Fountaine, Christopher M Cirnigliaro, Steven C Kirshblum, Cristin McKenna, William A Bauman
BACKGROUND: Interruption of sympathetic innervation to the liver and visceral adipose tissue (VAT) in animal models has been reported to reduce VAT lipolysis and hepatic secretion of very low density lipoprotein (VLDL) and concentrations of triglyceride-rich lipoprotein particles. Whether functional impairment of sympathetic nervous system (SNS) innervation to tissues of the abdominal cavity reduce circulating concentrations of triglyceride (TG) and VLDL particles (VLDL-P) was tested in men with spinal cord injury (SCI)...
2017: PloS One
https://www.readbyqxmd.com/read/28346431/real-time-impedance-monitoring-of-oxygen-reduction-during-surface-modification-of-thin%C3%A2-film%C3%A2-cathodes
#8
Ghislain M Rupp, Alexander K Opitz, Andreas Nenning, Andreas Limbeck, Jürgen Fleig
Improvement of solid oxide fuel cells strongly relies on the development of cathode materials with high catalytic activity for the oxygen reduction reaction. Excellent activity was found for perovskite-type oxides such as La1-xSrxCoO3-δ (LSC), but performance degradation, probably caused by surface composition changes, hinders exploitation of the full potential of LSC. This study reveals that the potentially very high activity of the LSC surface can be traced back to few very active sites. Already tiny amounts of SrO, for example, 4% of a monolayer, deposited on an LSC surface, lead to severe deactivation...
March 27, 2017: Nature Materials
https://www.readbyqxmd.com/read/28346376/blend-hydrogel-microspheres-of-carboxymethyl-chitosan-and-gelatin-for-the-controlled-release-of-5-fluorouracil
#9
Vanarchi Rajini Kanth, Praveen B Kajjari, Priya M Madalageri, Sakey Ravindra, Lata S Manjeshwar, Tejraj M Aminabhavi
Carboxymethyl chitosan (CMCS) was synthesized and blended with gelatin (GE) to prepare hydrogel microspheres by w/o emulsion cross-linking in the presence of glutaraldehyde (GA), which acted as a cross-linker. 5-Fluorouracil (5-FU) was encapsulated to investigate its controlled release (CR) characteristics in acidic (pH 1.2) and alkaline (pH 7.4) buffer media. The microspheres which formed were spherical in nature, with smooth surfaces, as judged by the scanning electron microscopy (SEM). Fourier transform infrared spectroscopy (FTIR) confirmed the carboxymethylation of CS and the chemical stability of 5-FU in the formulations...
March 27, 2017: Pharmaceutics
https://www.readbyqxmd.com/read/28346364/new-benzimidazole-1-2-4-triazole-hybrid-compounds-synthesis-anticandidal-activity-and-cytotoxicity-evaluation
#10
Hülya Karaca Gençer, Ulviye Acar Çevik, Serkan Levent, Begüm Nurpelin Sağlık, Büşra Korkut, Yusuf Özkay, Sinem Ilgın, Yusuf Öztürk
Owing to the growing need for antifungal agents, we synthesized a new series 2-((5-(4-(5-substituted-1H-benzimidazol-2-yl)phenyl)-4-substituted-4H-1,2,4-triazol-3-yl)thio)-1-(substitutedphenyl)ethan-1-one derivatives, which were tested against Candida species. The synthesized compounds were characterized and elucidated by FT-IR, ¹H-NMR, (13)C-NMR and HR-MS spectroscopies. The synthesized compounds were screened in vitro anticandidal activity against Candida species by broth microdiluation methods. In vitro cytotoxic effects of the final compounds were determined by MTT assay...
March 27, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28346215/enhanced-optoelectronic-quality-of-perovskite-films-with-excess-ch3nh3i-for-high-efficient-solar-cells-in-ambient-air
#11
Yunhai Zhang, Huiru Lv, Can Cui, Lingbo Xu, Peng Wang, Hao Wang, Xuegong Yu, Jiangsheng Xie, Jiabin Huang, Zeguo Tang, Deren Yang
The solution-processed polycrystalline perovskite film contributes critically to the high photovoltaic performance of perovskite based solar cells (PSCs). The inevitable electronic trap states at grain boundaries and the intrinsic defects such as metallic lead (Pb0) and halide vacancies in perovskite film cause serious carrier recombination loss. Furthermore, the film can easily decompose into PbI2 in moisture atmosphere. Here, we introduce a simple strategy through a small increase in methylammonium iodide (CH3NH3I, MAI) molar proportion (5%) for perovskite fabrication in ambient air with a ~50% relative humidity...
March 27, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28346122/non-targeted-metabolomics-in-sport-and-exercise-science
#12
Liam M Heaney, Kevin Deighton, Toru Suzuki
Metabolomics incorporates the study of metabolites that are produced and released through physiological processes at both the systemic and cellular levels. Biological compounds at the metabolite level are of paramount interest in the sport and exercise sciences, although research in this field has rarely been referred to with the global 'omics terminology. Commonly studied metabolites in exercise science are notably within cellular pathways for adenosine triphosphate production such as glycolysis (e.g., pyruvate and lactate), β-oxidation of free fatty acids (e...
March 27, 2017: Journal of Sports Sciences
https://www.readbyqxmd.com/read/28345926/band-gap-opening-induced-by-the-structural-periodicity-in-epitaxial-graphene-buffer-layer
#13
Maya Narayanan Nair, Irene Palacio, Arlensiú Celis, Alberto Zobelli, Alexandre Gloter, Stefan Kubsky, Jean-Philippe Turmaud, Matthew Conrad, Claire Berger, Walter de Heer, Edward Henry Conrad, Amina Taleb-Ibrahimi, Antonio Tejeda
The epitaxial graphene buffer layer on the Si face of hexagonal SiC shows a promising band gap, which precise origin remains to be understood. In this work, we correlate the electronic to the atomic structure of the buffer layer by combining angle resolved photoemission spectroscopy (ARPES), scanning tunneling microscopy (STM) and high-resolution scanning transmission electron microscopy (HR-STEM). We show that the band structure in the buffer has an electronic periodicity related to the structural periodicity observed in STM images and published X-ray diffraction...
March 27, 2017: Nano Letters
https://www.readbyqxmd.com/read/28345918/direct-s0%C3%A2-t-excitation-of-a-conjugated-polymer-repeat-unit-unusual-spin-forbidden-transitions-probed-by-time-resolved-electron-paramagnetic-resonance-spectroscopy
#14
Deborah L Meyer, Florian Lombeck, Sven Huettner, Michael Sommer, Till Biskup
A detailed understanding of the electronic structure of semiconducting polymers and their building blocks is essential to develop efficient materials for organic electronics. (Time-resolved) electron paramagnetic resonance (EPR) is particularly suited to address these questions, allowing to directly detect paramagnetic states and to reveal their spin-multiplicity, besides its clearly superior resolution compared to optical meth- ods. We present here evidence for a direct S0→T optical excitation of distinct triplet states in the repeat unit of a conjugated polymer used in organic photovoltaics...
March 27, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28345915/observation-of-ph-induced-protein-reorientation-at-the-water-surface
#15
Konrad Meister, Steven Joop Roeters, Arja Paananen, Sander Woutersen, Jan Versluis, Géza R Szilvay, Huib J Bakker
Hydrophobins are surface-active proteins that form a hydrophobic, water-repelling film around aerial fungal structures. They have a compact, particle-like structure, in which hydrophilic and hydrophobic regions are spatially separated. This surface property renders them amphiphilic and is reminiscent of synthetic Janus particles. Here we report surface-specific chiral and non-chiral vibrational sum-frequency generation spectroscopy (VSFG) measurements of hydrophobins adsorbed to their natural place of action, the air-water interface...
March 27, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28345899/ammonia-borane-dehydrogenation-catalyzed-by-%C3%AE%C2%BA-4-ep3-co-h-ep3-e-ch2ch2pph2-3-e-n-p-and-h2-evolution-from-their-interaction-with-nh-acids
#16
Stefano Todisco, Lapo Luconi, Giuliano Giambastiani, Andrea Rossin, Maurizio Peruzzini, Igor E Golub, Oleg A Filippov, Natalia V Belkova, Elena S Shubina
Two Co(I) hydrides containing the tripodal polyphosphine ligand EP3, (κ(4)-EP3)Co(H) [E(CH2CH2PPh2)3; E = N (1), P (2)], have been exploited as ammonia borane (NH3BH3, AB) dehydrogenation catalysts in THF solution at T = 55 °C. The reaction has been analyzed experimentally through multinuclear ((11)B, (31)P{(1)H}, (1)H) NMR and IR spectroscopy, kinetic rate measurements, and kinetic isotope effect (KIE) determination with deuterated AB isotopologues. Both complexes are active in AB dehydrogenation, albeit with different rates and efficiency...
March 27, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28345884/canted-antiferromagnetism-on-rectangular-layers-of-fe-2-in-polymorphic-cafeseo
#17
Kwing To Lai, Alexander Christoph Komarek, Maria Teresa Fernández-Díaz, Pi-Shan Chang, Sungjoon Huh, Helge Rosner, Chang-Yang Kuo, Zhiwei Hu, Tun-Wen Pi, Peter Adler, Vadim Ksenofontov, Liu Hao Tjeng, Martin Valldor
From stoichiometric amounts of CaO, Fe, and Se, pure powders and single crystals of quaternary [Formula: see text] can be obtained by solid-state reaction and self-flux growth, respectively. The as-synthesized compound exhibits a polymorphic crystal structure, where the two modifications have different stacking sequences of [Formula: see text] layers. The two polymorphs have similar unit cells but different crystal symmetries (Cmc21 and Pnma), of which the former is non-centrosymmetric. Fe is divalent (d(6)) and high-spin, as proven by X-ray spectroscopy, Mössbauer spectroscopy, and powder neutron diffraction data...
March 27, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28345879/vibrational-probes-from-small-molecule-solvatochromism-theory-and-experiments-to-applications-in-complex-systems
#18
Bartosz Błasiak, Casey H Londergan, Lauren J Webb, Minhaeng Cho
The vibrational frequency of a chosen normal mode is one of the most accurately measurable spectroscopic properties of molecules in condensed phases. Accordingly, infrared absorption and Raman scattering spectroscopy have provided valuable information on both distributions and ensemble-average values of molecular vibrational frequencies, and these frequencies are now routinely used to investigate structure, conformation, and even absolute configuration of chemical and biological molecules of interest. Recent advancements in coherent time-domain nonlinear vibrational spectroscopy have allowed the study of heterogeneous distributions of local structures and thermally driven ultrafast fluctuations of vibrational frequencies...
March 27, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28345869/characterization-of-the-aerosol-based-synthesis-of-uranium-particles-as-a-potential-reference-material-for-micro-analytical-methods
#19
Ronald Middendorp, Martin Dürr, Alexander Knott, Fabien Pointurier, Dario Ferreira Sanchez, Valerie Ann Samson, Daniel Grolimund
A process for production of micrometer-sized particles composed of uranium oxide using aerosol spray pyrolysis is characterized with respect to the various production parameters. The aerosol is generated using a vibrating orifice aerosol generator providing monodisperse droplets, which are oxidized in a subsequent heat treatment. The final particles are characterized with micro analytical methods to determine size, shape, internal morphology, chemical and structural properties in order to assess the suitability of the produced particles as a reference material for micro analytical methods, in particular for mass-spectrometry...
March 27, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28345854/flexible-p-doped-carbon-cloth-vacuum-sealed-preparation-and-enhanced-na-storage-properties-as-binder-free-anode-for-sodium-ion-batteries
#20
Hong-Yan Lü, Xiao-Hua Zhang, Fang Wan, Dao-Sheng Liu, Chao-Ying Fan, Huan-Mei Xu, Guang Wang, Xing-Long Wu
In this work, a flexible and self-supporting P-doped carbon cloth (FPCC), which is composed of interwoven mesh of hollow microtubules with porous carbon walls, is prepared via a vacuum-sealed doping technology by employing the commercially available cotton cloth as sustainable and scalable raw material. When directly used as binder-free anode for sodium-ion batteries, the as-prepared FPCC delivers superior Na-storage properties in terms of specific capacity up to 242.4 mA h g-1, high initial Coulombic efficiency of ~72 %, excellent rate capabilities (e...
March 27, 2017: ACS Applied Materials & Interfaces
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