LiFePO<Subscript>4</Subscript> synthesized via melt synthesis using low-cost iron precursors

LiFePO₄/C material has been prepared using fast-melt synthesis method followed by grinding and carbon coating. The low-cost iron ore concentrate (IOC) and purified iron ore concentrate (IOP) were used as iron precursors in the melt process to reduce significantly the cost of LiFePO₄/C. The same product was also synthesized using pure Fe₂O₃ under similar conditions as reference. The physical-chemical and electrochemical properties of samples were investigated. The X-ray Diffraction (XRD) results confirm the formation of an olivine structure of LiFePO₄ with a minor amount of Li₃PO₄ and Li₄P₂O₇ impurities for all the samples but no Fe₂P. The power performances of LiFePO₄/C using low-cost iron precursors were close to the sample using pure Fe₂O₃ precursor although capacity in mAh g^?1 is somewhat lower. With the inherent presence of silicon and other metals species, multi-substitution may take place when using IOC as source of iron leading to a Li(Fe_1-yM_y)(P_1-xSi_x)O₄ general composition. Multi-substitution, however, allows a better cycling stability. Therefore, these iron precursors present a promising option in this field to reduce the cost of a large-scale synthesis of LiFePO₄/C for Li-ion batteries application.     

Preparation of heat treated Ni2MnGa thin film without silicon diffusion

The Ni₂MnGa ferromagnetic alloys are one of these smart materials, that show a great interest for micro-electromechanical systems (MEMS) and micro-opto-electromechanical systems (MOEMS) when they are deposited as a thin film by rf sputtering. These films can be sputtered on silicon wafer in order to be easily integrated in Si-based device. Indeed, the use of this kind of substrate is very interesting because of the several well-known micromachining and integration technologies. However only heat treated thin films shows good functional properties that lay the problem of the silicon diffusion, as usually observed in the literature. In this work, a process (rf-sputtering process and annealing treatment) is proposed to elaborate martensite Ni₂MnGa thin films on Si substrate without silicon diffusion. This paper presents results on samples annealed at 873 K during 6 h.     

Eco-friendly process toward collector- and binder-free,high-energy density electrodes for lithium-ion batteries

Journal of Solid State Electrochemistry - The preparation of collector- and binder-free, high-energy density cathodes made from carbon-coated LiFePO4 (C-LFP) and single-walled carbon nanotubes...     

Online H/D exchange liquid chromatography as a support for the mass spectrometric identification of the oxidation products of melatonin

The hydrogen–deuterium exchange of protonated melatonin and its in vitro oxidation end‐products have been examined by liquid chromatography coupled with ion‐trap mass spectrometry. Specific H/D scrambling of protons in the C2 and C4 positions of the indole ring during gas‐phase fragmentation process was observed for both melatonin and its oxidation products. Collision‐induced dissociation spectra showed losses of variably deuterated NH₃, H₂O and CH₃CONH₂. In addition, a similar H/D scrambling behaviour was observed for the oxidation products, obtained from the opening of the indole ring by oxidative attack. Fragmentation pathways are proposed and H/D scrambling has been employed as a fingerprint, allowing identification of N¹‐acetyl‐5‐methoxykynurenin (AMK), N¹‐acetyl‐N²‐formyl‐5‐methoxykynurenin (AFMK), dehydro‐AFMK and hydroxymelatonin as the oxidation products of melatonin in vitro. Copyright © 2008 John Wiley & Sons, Ltd.     

Liquid chromatographic/electrospray ionization mass spectrometric identification of the oxidation end‐products of trans‐resveratrol in aqueous solutions

trans‐Resveratrol (3,5,4′‐trihydroxystilbene) is a natural polyphenolic compound that exhibits antioxidant properties. Our study aimed at studying the HO ^. ‐induced oxidation of resveratrol (100 µmol.L^?1) in aerated aqueous solutions. Gamma radiolysis of water was used to generate HO ^. /O free radicals (I = 10 Gy.min^?1, dose = 400 Gy). Oxidation products were identified by direct infusion mass spectrometry and high‐performance liquid chromatography/mass spectrometry. For each product, structural elucidation was based on simple mass spectra, fragmentation spectra and deuterium/hydrogen exchange spectra; the comparison with mass spectra of synthetic products provided valuable information allowing the complete identification of the oxidation products. Four products resulting from the direct attack of HO ^. radicals towards resveratrol were identified respectively as piceatannol (trans‐3,5,3′,4′‐tetrahydroxystilbene), 3,5‐dihydroxybenzoic acid, 3,5‐dihydroxybenzaldehyde and 4‐hydroxybenzaldehyde. Copyright © 2010 John Wiley & Sons, Ltd.     

The structural analysis of large noncovalent oxygen binding proteins by MALLS and ESI-MS: a review on annelid hexagonal bilayer hemoglobin and crustacean hemocyanin

Understanding the function of macromolecular complexes is related to a precise knowledge of their structure. These large complexes are often fragile high molecular mass noncovalent multimeric proteins. Classical biochemical methods for determination of their native mass and subunit composition were used to resolve their quaternary structure, sometimes leading to different models. Recently, the development of mass spectrometry and multi-angle laser light scattering (MALLS) has enabled absolute determination of native masses and subunit masses. Electrospray ionization mass spectrometry (ESI-MS) was used in denaturing and native conditions to probe subunit composition and noncovalent assemblies masses up to 2.25 MDa. In a complementary way, MALLS provides mass and size estimation in various aqueous solvents. ESI-MS method can also give insights into post-translational modifications (glycosylation, disulfide bridges ). By combining native mass and subunit composition data, structural models can be proposed for large edifices such as annelid extracellular hexagonal bilayer hemoglobins (HBL Hb) and crustacean hemocyanins (Hc). Association/dissociation mechanisms, protein-protein interactions, structural diversity among species and environmental adaptations can also be addressed with these methods. With their absolute mass determination, the very high precision of spectrometry and the versatile nature of light scattering, ESI-MS and MALLS have provided a wealth of data helping to resolve parts of controversies for HBL-Hb models and opening access to new fields of investigation in structural diversity and molecular adaptation. In this review we will focus on annelid HBL-Hb and on crustacean Hc and on the original contributions of ESI-MS and MALLS in this field.     

Control of the LiFePO4 electrochemical properties using low-cost iron precursor in a melt process

Journal of Solid State Electrochemistry - LiFePO4 was prepared from low-cost iron ore concentrate (containing 4.48&nbsp;wt.% SiO2 and MgO, CaO and Al2O3 below 0.5&nbsp;wt.% as contaminant)...     

Mixed integer programming formulations for the generalized traveling salesman problem with time windows

4OR - The generalized traveling salesman problem with time windows (GTSPTW) is defined on a directed graph where the vertex set is partitioned into clusters. One cluster contains only the depot....     

Betulin,a Newly Characterized Compound in Acacia auriculiformis Bark,Is a Multi-Target Protein Kinase Inhibitor

The purpose of this work is to investigate the protein kinase inhibitory activity of constituents from Acacia auriculiformis stem bark. Column chromatography and NMR spectroscopy were used to purify and characterize betulin from an ethyl acetate soluble fraction of acacia bark. Betulin, a known inducer of apoptosis, was screened against a panel of 16 disease-related protein kinases. Betulin was shown to inhibit Abelson murine leukemia viral oncogene homolog 1 (ABL1) kinase, casein kinase 1ε (CK1ε), glycogen synthase kinase 3α/β (GSK-3 α/β), Janus kinase 3 (JAK3), NIMA Related Kinase 6 (NEK6), and vascular endothelial growth factor receptor 2 kinase (VEGFR2) with activities in the micromolar range for each. The effect of betulin on the cell viability of doxorubicin-resistant K562R chronic myelogenous leukemia cells was then verified to investigate its putative use as an anti-cancer compound. Betulin was shown to modulate the mitogen-activated protein (MAP) kinase pathway, with activity similar to that of imatinib mesylate, a known ABL1 kinase inhibitor. The interaction of betulin and ABL1 was studied by molecular docking, revealing an interaction of the inhibitor with the ABL1 ATP binding pocket. Together, these data demonstrate that betulin is a multi-target inhibitor of protein kinases, an activity that can contribute to the anticancer properties of the natural compound and to potential treatments for leukemia.     

Effect of the Peptidic Scaffold in Copper(II) Coordination and the Redox Properties of Short Histidine‐Containing Peptides

A linear decapeptide containing three His and one Asp residues and a β‐turn‐inducing dProPro unit was synthesised. A detailed potentiometric, mass spectrometric and spectroscopic study showed that at a 1:1 ratio of C_Cu/C_peptide this peptide formed a major [CuH(O_dPro?Asp)]²⁺ species (pH range 5.5–7.0), in which the Cu²⁺ ion was bound to the His and Asp residues in square‐planar or square‐pyramidal geometries. The stability constant corrected for protonated species (log K*=9.33) is almost equal to the value obtained for the parent [CuH(O?Asp)]²⁺ species (log K*_CuH(O‐Asp)=9.28), but lower than that obtained for the cyclic [CuH(C?Asp)]²⁺ complex (log K*_CuH(C‐Asp)=10.79) previously published. Thus, the replacement of the ProGly unit by the stronger β‐turn‐inducing dProPro unit did not generate a more stable copper(II) species, although the O_dPro?Asp peptide was structured in solution, as shown by circular dichroism (CD) spectroscopy. Interestingly, the calculated value of K_eff showed that this peptide behaved similarly to the O?Asp or C?Asp counterparts, depending on the pH value. The cyclic voltammetry data indicated that the most easily reducible species were [CuH(O?Asp)]²⁺ (E′⁰=262 mV versus a normal hydrogen electrode (NHE)) and [CuH(O_dPro?Asp)]²⁺ (E′⁰=294 mV versus NHE) complexes, the peptidic scaffolds of which are open. A lower value was obtained for [CuH(C?Asp)]²⁺ (E′⁰=24 mV versus NHE). A different degree of non‐reversibility was observed for the three copper(II) complexes; this could reflect a different degree of flexibility in their respective peptidic scaffolds.