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Beata Borowiak-Sobkowiak, Agnieszka Woźniak, Waldemar Bednarski, Magda Formela, Sławomir Samardakiewicz, Iwona Morkunas
The aim of this study was to investigate whether and to what extent oxidative stress is induced in leaves of one- and two-month-old plants of Asparagus officinalis L. cv. Argenteuil infested by Brachycorynella asparagi (Mordvilko) at a varied population size. The pest B. asparagi has been described as the most damaging species feeding on asparagus. Analyses using electron paramagnetic resonance (EPR) demonstrated generally higher concentrations of semiquinone radicals with g-values of 2.0045 ± 0.0005 and 2...
October 20, 2016: International Journal of Molecular Sciences
Kelly Souza Fernandes, Paulo Eduardo Narcizo de Souza, Miriam Leandro Dorta, Antonio Alonso
In this study, we combined electron paramagnetic resonance (EPR) spectroscopy with an analysis of biophysical cellular parameters to study the mechanisms underlying the in vitro anti-leishmanial activity of miltefosine (MT). A thiol-specific spin label attached to membrane-bound proteins of Leishmania amazonensis and peritoneal macrophages indicated that MT may bind to plasma membrane proteins in large quantities via a detergent-like action and cause structural changes associated with a marked increase in dynamics and exposure to an aqueous environment...
October 20, 2016: Biochimica et Biophysica Acta
Jie Liu, Jihao Zhou, Zhaoxia Ding, Zhiwei Zhao, Xiao Xu, Zhendong Fang
Magnetic Fe3O4 nanoparticles were synthesized and used as peroxymonosulfate (PMS) activator in the presence of ultrasound (US) irritation for azo dye degradation in this study. At pH 7.0 and temperature 298K, Fe3O4 nanoparticles were able to activate PMS under ultrasound irritation to produce sulfate radicals for acid orange 7 (AO7) removal in 30min. Higher catalysts dosage, neutral pH as well as optimum values of PMS dosage and ultrasound power favored the AO7 degradation. Fe3O4 displayed excellent stability and reusability in the US/PMS system...
January 2017: Ultrasonics Sonochemistry
Davide Sala, Andrea Giachetti, Claudio Luchinat, Antonio Rosato
The binding of paramagnetic metal ions to proteins produces a number of different effects on the NMR spectra of the system. In particular, when the magnetic susceptibility of the metal ion is anisotropic, pseudocontact shifts (PCSs) arise and can be easily measured. They constitute very useful restraints for the solution structure determination of metal-binding proteins. In this context, there has been great interest in the use of lanthanide(III) ions to induce PCSs in diamagnetic proteins, e.g. through the replacement native calcium(II) ions...
October 22, 2016: Journal of Biomolecular NMR
Shamsa Aliramaji, Ali Zamanian, Masoud Mozafari
Tissue engineering is a promising approach in repairing damaged tissues. During the last few years, magnetic nanoparticles have been of great interest in this field of study due to their controlled responsive characteristics in specific external magnetic fields. In this study, after synthesizing iron oxide (magnetite) nanoparticles through a reverse coprecipitation method, silk fibroin/chitosan-based magnetic scaffolds were prepared using different amounts of magnetite nanoparticles (0, 0.5, 1 and 2%) by freeze-casting method...
January 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
G S Polymeris, V Giannoulatou, A Kyriakidou, I K Sfampa, G S Theodorou, E Şahiner, N Meriç, G Kitis, K M Paraskevopoulos
The current work exploits the effective application of thermoluminescence (TL), optically stimulated luminescence (OSL) and the possibility of applying Electron Paramagnetic Resonance (EPR) for the discrimination between different bioactive responses in the case of the 45S5 bioactive glass (SiO2 45, Na2O 24.5, CaO 24.5, P2O5 6 in wt%), which was synthesized through melting process. These techniques are suggested mainly due to their low spectroscopic detection thresholds. The original 45S5 in grain size range of 20-40μm was immersed in the Simulated Body Fluid (SBF) for various different immersion times ranging over one week...
January 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
Junki Yoshitake, Joji Nasu, Yukitoshi Motome
Experimental identification of quantum spin liquids remains a challenge, as the pristine nature is to be seen in asymptotically low temperatures. We here theoretically show that the precursor of quantum spin liquids appears in the spin dynamics in the paramagnetic state over a wide temperature range. Using the cluster dynamical mean-field theory and the continuous-time quantum Monte Carlo method, which are newly developed in the Majorana fermion representation, we calculate the dynamical spin structure factor, relaxation rate in nuclear magnetic resonance, and magnetic susceptibility for the honeycomb Kitaev model whose ground state is a canonical example of the quantum spin liquid...
October 7, 2016: Physical Review Letters
Joshua R Biller, Deborah G Mitchell, Mark Tseytlin, Hanan Elajaili, George A Rinard, Richard W Quine, Sandra S Eaton, Gareth R Eaton
We demonstrate a superior method of 2D spectral-spatial imaging of stable radical reporter molecules at 250 MHz using rapid-scan electron-paramagnetic-resonance (RS-EPR), which can provide quantitative information under in vivo conditions on oxygen concentration, pH, redox status and concentration of signaling molecules (i.e., OH(•), NO(•)). The RS-EPR technique has a higher sensitivity, improved spatial resolution (1 mm), and shorter acquisition time in comparison to the standard continuous wave (CW) technique...
September 26, 2016: Journal of Visualized Experiments: JoVE
Shan Wang, Changmin Hou, Long Yuan, Mingyang Qu, Bo Zou, Dayong Lu
Perovskite structured rare-earth chromites are one of the most promising families of functional materials in solid oxide fuel cells, multiferroic materials, and sensors. Here, we report a mild hydrothermal method to synthesize DyCrO3 and HoCrO3 monodispersed single crystals. The synthesis conditions, crystal structure, Raman spectra and temperature- and field-dependent magnetic properties were studied. The two samples are indexed to the Pbnm space group. The shapes of the crystals are plates with a narrow particle size distribution in the range of 4-5 μm...
October 21, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Curt Wentrup, Michèle J Regimbald-Krnel, Dennis Müller, Peter Comba
Variable-temperature NMR and ESR spectroscopic studies reveal that bis(dibenzo[a,i]fluorenylidene) 1 possesses a singlet ground state, 1(S0 ), while the 90° twisted triplet 1(T1 ) is populated to a small extent already at room temperature. Analysis of the increasing amount of paramagnetic 1(T1 ) at temperatures between 300 and 500 K yields the exchange interaction Jex /h c=3351 cm(-1) and a singlet-triplet energy splitting of 9.6 kcal mol(-1) , which is in excellent agreement with calculations (9...
October 20, 2016: Angewandte Chemie
Christoph Göbl, Moritz Resch, Madeleine Strickland, Christoph Hartlmüller, Martin Viertler, Nico Tjandra, Tobias Madl
The study of intrinsically disordered proteins (IDPs) by NMR often suffers from highly overlapped resonances that prevent unambiguous chemical-shift assignments, and data analysis that relies on well-separated resonances. We present a covalent paramagnetic lanthanide-binding tag (LBT) for increasing the chemical-shift dispersion and facilitating the chemical-shift assignment of challenging, repeat-containing IDPs. Linkage of the DOTA-based LBT to a cysteine residue induces pseudo-contact shifts (PCS) for resonances more than 20 residues from the spin-labeling site...
October 20, 2016: Angewandte Chemie
Chuanguang Yao, Hongxin Song, Ying Wan, Kefeng Ma, Chenyu Zheng, Hongda Cui, Peng Xin, Xubo Ji, Sheng-Yuan Deng
A porphyrin-based electro-photodynamic imaging system was fabricated for monitoring the concentration of oxygen. Distinct from the electrochemiluminescent (ECL) inability of numerous organic species in aqueous solutions, a strong and stable red irradiation at 634 nm could be stimulated electrochemically on zinc(II) meso-tetra(4-carboxyphenyl) porphine (ZnTCPP)/tetraoctylammonium bromide (TOAB) in the physiological condition. In terms of in situ electron paramagnetic resonance and ECL spectroscopies, the nature of ECL was thoroughly investigated, being exactly the chemiluminescence from singlet oxygen (1O2) produced during the successive electro-reduction of ZnTCPP...
October 20, 2016: ACS Applied Materials & Interfaces
Wei-Tao Wu, Andrea Blue Martin, Alberto Gandini, Nadine Aubry, Mehrdad Massoudi, James F Antaki
This study is motivated by the development of a blood cell filtration device for removal of malaria-infected, parasitized red blood cells (pRBCs). The blood was modeled as a multi-component fluid using the computational fluid dynamics discrete element method (CFD-DEM), wherein plasma was treated as a Newtonian fluid and the red blood cells (RBCs) were modeled as soft-sphere solid particles which move under the influence of drag, collisions with other RBCs, and a magnetic force. The CFD-DEM model was first validated by a comparison with experimental data from Han et al...
2016: Microfluidics and Nanofluidics
Somasundaram Ramasamy, Mohammad Mahfuzul Haque, Mahinda Gangoda, Dennis J Stuehr
The NO synthases (NOS) catalyze a two-step oxidation of L-Arginine (Arg) to generate NO. In the first step, O2 activation involves one electron being provided to the heme by an enzyme-bound 6R-tetrahydro-L-biopterin cofactor (H4 B), which then forms a H4 B radical that must be reduced back to H4 B in order for NOS to continue catalysis. Although an NADPH-derived electron is used to reduce the H4 B radical, how this occurs is unknown. We hypothesized that the NOS flavoprotein domain might reduce the H4 B radical by utilizing the NOS heme porphyrin as a conduit to deliver the electron...
October 19, 2016: FEBS Journal
Yang Yu, Igor Petrik, Kelly N Chacón, Parisa Hosseinzadeh, Honghui Chen, Ninian J Blackburn, Yi Lu
Type 1 copper (T1Cu) proteins are electron transfer (ET) proteins involved in many important biological processes. While the effects of changing primary and secondary coordination spheres in the T1Cu ET function have been extensively studied, no report has explored the effect of the overall protein structural perturbation on active site configuration or reduction potential of the protein, even though the protein scaffold has been proposed to play a critical role in enforcing the entatic or "rack-induced" state for ET functions...
October 19, 2016: Protein Science: a Publication of the Protein Society
S Saeidpour, S B Lohan, M Anske, M Unbehauen, E Fleige, R Haag, M C Meinke, R Bittl, C Teutloff
The skin and especially the stratum corneum (SC) act as a barrier and protect epidermal cells and thus the whole body against xenobiotica of the external environment. Topical skin treatment requires an efficient drug delivery system (DDS). Polymer-based nanocarriers represent novel transport vehicles for dermal application of drugs. In this study dendritic core-multishell (CMS) nanoparticles were investigated as promising candidates. CMS were loaded with a drug (analogue) and were applied to penetration studies of skin...
October 15, 2016: European Journal of Pharmaceutics and Biopharmaceutics
Ewa Kober, Zofia Janas, Julia Jezierska
A series of oxidovanadium(V) complexes [VO(L-κ(4)O,N,N,O)(OR)] (1a, R = Et, L = L(1); 1b, R = Me, L = L(1); 2, R = Me, L = L(2); 3, R = Me, L = L(3)) were synthesized by the σ-bond metathesis reaction between [VO(OR)3] and the linear diaminebis(phenol) derivatives H2L (salans) containing different para-substituents on the phenoxo group [CMe3CH2CMe2, L(1); Me, L(2); Cl, L(3)]. As shown by X-ray crystallography complexes 1a, 1b, and 2 exhibit cis-α geometry, do have a stereogenic vanadium center, and exist as a racemic mixture of the Δ cis-α and Λ cis-α enantiomers...
October 18, 2016: Inorganic Chemistry
Dominik Kurzydłowski, Tomasz Jaroń, Andrew Ozarowski, Stephen Hill, Zvonko Jagličić, Yaroslav Filinchuk, Zoran Mazej, Wojciech Grochala
The crystal structure, magnetic properties, heat capacity, and Raman spectra of double-perovskite M2AgF4 (M = K, K3/4Rb1/4, K1/2Rb1/2, K1/4Rb3/4, and Rb) phases have been examined, adding to the body of previous results for the M = Na, Cs derivatives. The results suggest that double-perovskite K2AgF4 adopts a disordered orthorhombic Bmab structure with an antiferrodistortive arrangement of the elongated and tilted [AgF6] octahedra rather than the structure with the ferrodistortive arrangement of compressed octahedra, as suggested previously (Mazej, Z...
October 18, 2016: Inorganic Chemistry
Matvey V Fedin, Georgiy Yu Shevelev, Dmitrii V Pyshnyi, Victor M Tormyshev, Gunnar Jeschke, Maxim Yulikov, Elena G Bagryanskaya
Spin labels selectively attached to biomolecules allow high-accuracy nanoscale distance measurements using pulsed electron paramagnetic resonance (EPR), in many cases providing the only access to the structure of complex biosystems. Triarylmethyl (TAM) radicals have recently emerged as a new class of spin labels expanding the applicability of the method to physiological temperatures. Along with other factors, the accuracy of the obtained distances crucially relies on the understanding of interactions between biomolecules and spin labels...
October 17, 2016: Physical Chemistry Chemical Physics: PCCP
Qiang Hao, Xiuxiu Niu, Changshun Nie, Simeng Hao, Wei Zou, Jiangman Ge, Daimei Chen, Wenqing Yao
SiO2, an insulator, hardly has any photocatalytic acitivity due to its intrinsic property, and it is generally used as a hard template to increase the surface area of catalysts. However, in this work, we found that the surface state of the insulator SiO2 can promote the migration of photogenerated charge carriers, leading to the enhancement of the photooxidation ability of graphitic carbon nitride (g-C3N4). A one-pot calcination method was employed to prepare g-C3N4/SiO2 composites using melamine and SiO2 as precursors...
October 17, 2016: Physical Chemistry Chemical Physics: PCCP
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