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Yue Chen, Yuanyuan Zhang, Qiangwei Kou, Yang Liu, Donglai Han, Dandan Wang, Yantao Sun, Yongjun Zhang, Yaxin Wang, Ziyang Lu, Lei Chen, Jinghai Yang, Scott Guozhong Xing
In this work, we report the enhanced catalytic reduction of 4-nitrophenol driven by Fe₃O₄-Au magnetic nanocomposite interface engineering. A facile solvothermal method is employed for Fe₃O₄ hollow microspheres and Fe₃O₄-Au magnetic nanocomposite synthesis via a seed deposition process. Complementary structural, chemical composition and valence state studies validate that the as-obtained samples are formed in a pure magnetite phase. A series of characterizations including conventional scanning/transmission electron microscopy (SEM/TEM), Mössbauer spectroscopy, magnetic testing and elemental mapping is conducted to unveil the structural and physical characteristics of the developed Fe₃O₄-Au magnetic nanocomposites...
May 22, 2018: Nanomaterials
Derang Cao, Lining Pan, Jianan Li, Xiaohong Cheng, Zhong Zhao, Jie Xu, Qiang Li, Xia Wang, Shandong Li, Jianbo Wang, Qingfang Liu
Carbon or nitrogen doped cobalt ferrite nanoparticles were synthesized in the air by a facile calcination process. X-ray diffraction, mapping, X-ray photoelectron spectroscopy, and mössbauer spectra results indicate that the nonmetal elements as the interstitial one are doped into cobalt ferrite nanoparticles. The morphologies of doped cobalt ferrite nanoparticles change from near-spherical to irregular cubelike shapes gradually with the increased carbon or nitrogen concentration, and their particles sizes also increase more than 200 nm...
May 21, 2018: Scientific Reports
Golam Moula, Tsuyoshi Matsumoto, Matthias E Miehlich, Karsten Meyer, Kazuyuki Tatsumi
An unprecedented, super oxidized all-ferric iron-sulfur cubanoid cluster with all terminal thiolates, Fe₄S₄(STbt)₄ (3) [Tbt = 2,4,6-tris{bis(trimethylsilyl)methyl}phenyl], has been isolated from the reaction of the bis-thiolate complex Fe(STbt)₂ (2) with elemental sulfur. This cluster 3 has been characterized by X-ray crystallography, zero-field ⁵⁷Fe Mössbauer spectroscopy, cyclic voltammetry, and other relevant physico-chemical methods. Based on all data, the electronic ground state of the cluster has been assigned to be Stot = 0...
May 18, 2018: Angewandte Chemie
Yurii D Perfiliev, Alexandr Kh Tambiev, Maxim A Konnychev, Anatoly V Skalny, Elena S Lobakova, Mikhail P Kirpichnikov
In the present paper, Mössbauer spectroscopic studies of dry biomass samples of the cyanobacterium Arthrospira platensis (formerly known as Spirulina platensis) were performed with regard to metabolic iron accumulation. 57 Fe Mössbauer parameters of iron in the biomass correspond to ferrihydrite. Spectra of iron hydroxides in A. platensis biomass differ from those of iron complexes with ethylenediaminetetraacetic acid injected to Zarrouk culture medium. The limit of saturation of A. platensis trichomes with iron in the form of ferrihydrite was found to be 5 μg/ml (0...
July 2018: Journal of Trace Elements in Medicine and Biology
Franziska Steudel, Jacqueline A Johnson, Charles E Johnson, Stefan Schweizer
The application of Mössbauer spectroscopy to luminescent materials is described. Many solids doped with europium are luminescent, i.e., when irradiated with light they emit light of a longer wavelength. These materials therefore have practical applications in tuning the light output of devices like light emitting diodes. The optical properties are very different for the two possible valence states Eu 2 + and Eu 3 + , the former producing ultraviolet/visible light that shifts from violet to red depending on the host and the latter red light, so it is important to have a knowledge of their behavior in a sample environment...
May 17, 2018: Materials
Floriana Craciun, Francesco Cordero, Bogdan S Vasile, Victor Fruth, Maria Zaharescu, Irina Atkinson, Roxana Trusca, Lucian Diamandescu, Liviu C Tanase, Pietro Galizia, Marin Cernea, Carmen Galassi
The formation of separate phases in crystalline materials is promoted by doping with elements with different valences and ionic radii. Control of the formation of separate phases in multiferroics is extremely important for their magnetic, ferroelectric and elastic properties, which are relevant for multifunctional applications. The ordering of dopants and incipient phase separation were studied in lead titanate-based multiferroics with the formula (Pb0.88Nd0.08)(Ti0.98-xFexMn0.02)O3 (x = 0.00, 0.03, 0.04, 0...
May 17, 2018: Physical Chemistry Chemical Physics: PCCP
Anna Reuß, Vadim Ksenofontov, Joshua Tapp, Dirk Wulferding, Peter Lemmens, Martin Panthöfer, Angela Möller
BaNa2 Fe[VO4 ]2 contains a Jahn-Teller active ion (FeII , 3d6 , high-spin) in an octahedral coordination. On the basis of a combination of temperature-dependent X-ray diffraction and Mössbauer and Raman spectroscopies, we demonstrate the coupling of lattice dynamics with the electronic ground state of FeII . We identify three lattice modes combined to an effective canted screw- type motion that drives the structural transition around room temperature from the high-temperature ( P3̅) via intermediate phases to the low-temperature phase ( C2/ c)...
May 16, 2018: Inorganic Chemistry
Fumitaka Takeiri, Takafumi Yamamoto, Naoaki Hayashi, Saburo Hosokawa, Kazunari Arai, Jun Kikkawa, Kazutaka Ikeda, Takashi Honda, Toshiya Otomo, Cédric Tassel, Koji Kimoto, Hiroshi Kageyama
We synthesized a silver iron oxyfluoride AgFeOF2 by using a high-pressure reaction. Synchrotron X-ray and neutron diffraction, X-ray absorption, and 57 Fe Mössbauer spectroscopy indicate that AgFeOF2 crystallizes in the ideal perovskite structure with iron in a trivalent state, although electron microscopy revealed weak super-reflections. A possible partial ordering in the FeO2 F4 octahedron is inferred from Mössbauer spectroscopy. The synthesis of the fluorine-rich sample offers an opportunity to study a composition-property relation in AFeIII O3- n F n ( n = 0, 1, and 2)...
May 11, 2018: Inorganic Chemistry
Jordan A DeGayner, Kunyu Wang, T David Harris
We report the synthesis of a semiquinoid-bridged single-chain magnet, as generated through a thermally-induced metal-ligand electron transfer. Reaction of FeCl3 with 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone (LH2 ) in the presence of (NMe4 )Cl gave the compound (NMe4 )2 [LFeCl2 ]. A combined analysis of variable-temperature X-ray diffraction, Mössbauer spectra, Raman spectra, and dc magnetic susceptibility reveal a transition from a chain containing (L2- )FeII units to one with (L3-• )FeIII upon decreasing temperature, with a transition temperature of T1/2 = 213 K...
May 10, 2018: Journal of the American Chemical Society
Sven-Andreas Freibert, Benjamin D Weiler, Eckhard Bill, Antonio J Pierik, Ulrich Mühlenhoff, Roland Lill
Iron-sulfur (Fe/S) proteins are involved in numerous key biological functions such as respiration, metabolic processes, protein translation, DNA synthesis, and DNA repair. The simplest types of Fe/S clusters include [2Fe-2S], [3Fe-4S], and [4Fe-4S] forms that sometimes are present in multiple copies. De novo assembly of Fe/S cofactors and their insertion into apoproteins in living cells requires complex proteinaceous machineries that are frequently highly conserved. In eukaryotes such as yeast and mammals, the mitochondrial iron-sulfur cluster assembly machinery and the cytosolic iron-sulfur protein assembly system consist of more than 30 components that cooperate in the generation of some 50 cellular Fe/S proteins...
2018: Methods in Enzymology
Riccardo Di Corato, Alessandra Aloisi, Simona Rella, Jean-Marc Greneche, Giammarino Pugliese, Teresa Pellegrino, Cosimino Malitesta, Rosaria Rinaldi
In the field on nanomedicine, superparamagnetic nanoparticles are one of the most studied nanomaterials for theranostics. In this paper, a one-pot synthesis of magnetic nanoparticles is presented, with elevated control on particles size from 10 to 40 nm. The monitoring of vacuum level is here introduced as a crucial parameter for achieving a fine particle morphology. Magnetic properties of these nanoparticles are highly affected by disorders or mismatches in crystal structure. A prolonged oxidation step is applied to the obtained nanoparticles to transform the magnetic phases into a pure maghemite one, confirmed by a high resolution XPS analysis, by Mössbauer spectrometry and, indirectly, by increased performances in magnetization curves and in relaxation times...
May 10, 2018: ACS Applied Materials & Interfaces
Ana I Vicente, Liliana P Ferreira, Maria de Deus Carvalho, Vítor H N Rodrigues, Marinela M Dîrtu, Yann Garcia, Maria José Calhorda, Paulo N Martinho
Two polymorphic species of the [Fe(5-Br-salEen)2]ClO4 compound were obtained, each of them being selectively recovered after evaporation of the solvent at a controlled rate. While polymorph 1a is formed during slow evaporation, fast evaporation favors polymorph 1b. The importance of the evaporation rate was recognized after detailed studies of the reaction temperature, solvent evaporation rate and crystallization temperature effects. The complex in the new polymorphic form 1a showed an abrupt spin crossover at 172 K with a small 1 K hysteresis window and over a narrow 10 K range...
May 8, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Yong Feng, Changzhong Liao, Lingjun Kong, Deli Wu, Yiming Liu, Po-Heng Lee, Kaimin Shih
Ferrous ions (Fe2+ ) are environmentally friendly materials but show extremely inefficient persulfate activation. Polymeric graphitic carbon nitride (g-C3 N4 ) has recently shown potential to activate persulfates, but the process requires intense light irradiation. To overcome these drawbacks, we designed an innovative heterogeneous iron catalyst by doping Fe into g-C3 N4 (Fe-g-C3 N4 ) and used it to activate peroxymonosulfate (PMS) for degradation of pollutant phenol. The catalysts synthesized were fully characterized with various techniques, such as X-ray diffraction, Mössbauer spectroscopy, and X-ray photoelectron spectroscopy...
April 25, 2018: Journal of Hazardous Materials
A V Kuzikov, R A Masamrekh, A I Archakov, V V Shumyantseva
The review is dedicated to modern methods and technologies for determining of cytochrome P450 isozymes functional activity, such as absorbance and fluorescent spectroscopy, electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR), Raman, Mossbauer, and X-ray spectroscopy, surface plasmon resonance (SPR), atomic force microscopy (AFM). Methods of molecular genetic analysis were reviewed from personalized medicine point of view. The use of chromate-mass-spectrometric methods for cytochrome P450-dependent catalytic reactions' products was discussed...
March 2018: Biomedit︠s︡inskai︠a︡ Khimii︠a︡
Divya Prakash, Karim A Walters, Ryan J Martinie, Addison C McCarver, Adepu K Kumar, Daniel J Lessner, Carsten Krebs, John H Golbeck, James G Ferry
Disulfide reductases reduce other proteins and are critically important for cellular redox signaling and homeostasis. Methanosarcina acetivorans is a methane-producing microbe from the domain Archaea that produces a ferredoxin:disulfide reductase (FDR) for which the crystal structure has been reported, yet its biochemical mechanism and physiological substrates are unknown. FDR and the extensively characterized plant-type ferredoxin:thioredoxin reductase (FTR) belong to a distinct class of disulfide reductases that contain a unique active-site [4Fe-4S] cluster...
May 2, 2018: Journal of Biological Chemistry
Samuel M Greer, Johannes McKay, Kathryn M Gramigna, Christine M Thomas, Sebastian A Stoian, Stephen Hill
Direct metal-metal bonding of two distinct first-row transition metals remains relatively unexplored compared to their second- and third-row heterobimetallic counterparts. Herein, a recently reported Fe-V triply bonded species, [V( i PrNPPh2 )3 FeI] (1; Kuppuswamy, S.; Powers, T. M.; Krogman, J. P.; Bezpalko, M. W.; Foxman, B. M.; Thomas, C. M. Vanadium-iron complexes featuring metal-metal multiple bonds. Chem. Sci. 2013, 4, 3557-3565), is investigated using high-frequency electron paramagnetic resonance, field- and temperature-dependent 57 Fe nuclear gamma resonance (Mössbauer) spectroscopy, and high-field electron-electron double resonance detected nuclear magnetic resonance...
April 30, 2018: Inorganic Chemistry
M I Oshtrakh
A brief review on the applications of Mössbauer spectroscopy in biomedical research discusses the results of more than fifty years of experience in this field. Basing on the numerous results the main directions of biomedical applications of Mössbauer spectroscopy are considered as follows: 1) studies of the quantitative changes of iron-containing biomolecules related to pathological processes; 2) studies of the qualitative changes in iron-containing biomolecules related to pathological processes; 3) studies of the effect of various environmental factors (physical, chemical, and biological) on iron-containing biomolecules; 4) studies of metabolic processes by means of analysis of the Mössbauer nuclides pathways in organisms; 5) studies of dynamic processes; 6) studies of pharmaceutical compounds and blood substitutes containing Mössbauer nuclides; 7) miscellaneous studies...
April 27, 2018: Cell Biochemistry and Biophysics
M A Peck, G R Hearne, C Obuah, J Darkwa
57Fe Mössbauer spectroscopy has been used to study electronic dispersions in complexes of Fe, Co, Ni and Pd anchored onto 3-ferrocenyl-5-methylpyrazolylmethylenepyridine and 3-ferrocenylpyrazolylmethylenepyridine ligands. Mössbauer spectroscopy shows that pyrazolyl-derivatizing of ferrocene increases the electron-density at the Fe-centre as well as facilitating the Fe to cyclopentadienyl ring back-donation of electron-density. The coordination of the ferrocenyl-pyrazolyl ligand to transition metals such as Fe, Co, Ni and Pd reduces the electron-density at the Fe-centre of the ferrocenyl moiety while increasing the electron-density at the coordinated metal centre, especially in the Fe complexes...
April 20, 2018: Physical Chemistry Chemical Physics: PCCP
Valerie E Fleischauer, Salvador B Muñoz Iii, Peter G N Neate, William W Brennessel, Michael L Neidig
While iron-NHC catalysed cross-couplings have been shown to be effective for a wide variety of reactions ( e.g. aryl-aryl, aryl-alkyl, alkyl-alkyl), the nature of the in situ formed and reactive iron species in effective catalytic systems remains largely undefined. In the current study, freeze-trapped Mössbauer spectroscopy, and EPR studies combined with inorganic synthesis and reaction studies are utilised to define the key in situ formed and reactive iron-NHC species in the Kumada alkyl-alkyl cross-coupling of (2-(1,3-dioxan-2-yl)ethyl)magnesium bromide and 1-iodo-3-phenylpropane...
February 21, 2018: Chemical Science
Weishen Yang, Kaiyue Zhu, Xuefeng Zhu
Developing high-efficiency and affordable electrocatalysts for the sluggish oxygen evolution reaction (OER) remains a crucial bottleneck on the way to the practical applications of rechargeable energy storage technologies and water splitting for producing clean fuel (H2). In recent years, NiFe based materials have demonstrated to be excellent electrocatalysts for OER. Understanding the characteristics that affect OER activity and determining the OER mechanism are of vital importance for the development of OER electrocatalysts...
April 17, 2018: Angewandte Chemie
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