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Deterioration mechanisms of LiCoO 2 electrode materials for lithium ion batteries remain unclear. Using electron energy-loss spectroscopy and transmission electron microscopy, this study investigated chemical states of LiCoO 2 particles on first overcharging. We present a scheme for quantification of the Li/ Co atomic ratio. Using quantitative Li mapping and comprehensive probing of Li−K, Co−M 2,3 , Co−L 3 , and O−K edges, we observed that overcharging causes the progression of Co 3+ /Co 2+ reduction with oxygen extraction from the particle surface to the interior. A gradual change in the chemical composition at and around the particle surfaces after charging of 60% revealed the presence of Co 3 O 4 -like and CoO-like phases at surface regions. We also observed nanocracks with deficient Li ions. These results are key factors affecting degradation on overcharging.

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A new tetradentate tripodal ligand (L3) containing sterically bulky imidazolyl groups was synthesized, where L3 is tris(1-methyl-2-phenyl-4-imidazolylmethyl)amine. Reaction of a bis(mu-hydroxo)dicopper(II) complex, [Cu2(L3)2(OH)2]2+ (1), with H2O2 in acetonitrile at -40 degrees C generated a (mu-1,1-hydroperoxo)dicopper(II) complex [Cu2(L3)2(OOH)(OH)]2+ (2), which was characterized by various physicochemical measurements including X-ray crystallography. The crystal structure of 2 revealed that the complex cation has a Cu2(mu-1,1-OOH)(mu-OH) core and each copper has a square pyramidal structure having an N3O2 donor set with a weak ligation of a tertiary amine nitrogen in the apex. Consequently, one pendant arm of L3 in 2 is free from coordination, which produces a hydrophobic cavity around the Cu2(mu-1,1-OOH)(mu-OH) core. The hydrophobic cavity is preserved by hydrogen bondings between the hydroperoxide and the imidazole nitrogen of an uncoordinated pendant arm in one side and the hydroxide and the imidazole nitrogen of an uncoordinated pendant arm in the other side. The hydrophobic cavity significantly suppresses the H/D and 16O/18O exchange reactions in 2 compared to that in 1 and stabilizes the Cu2(mu-1,1-OOH)(mu-OH) core against decomposition. Decomposition of 2 in acetonitrile at 0 degrees C proceeded mainly via disproportionation of the hydroperoxo ligand and reduction of 2 to [Cu(L3)]+ by hydroperoxo ligand. In contrast, decomposition of a solid sample of 2 at 60 degrees C gave a complex having a hydroxylated ligand [Cu2(L3)(L3-OH)(OH)2]2+ (2-(L3-OH)) as a main product, where L3-OH is an oxidized ligand in which one of the methylene groups of the pendant arms is hydroxylated. ESI-TOF/MS measurement showed that complex 2-(L3-OH) is stable in acetonitrile at -40 degrees C, whereas warming 2-(L3-OH) at room temperature resulted in the N-dealkylation from L3-OH to give an N-dealkylated ligand, bis(1-methyl-2-phenyl-4-imidazolylmethyl)amine (L2) in approximately 80% yield based on 2, and 1-methyl-2-phenyl-4-formylimidazole (Phim-CHO). Isotope labeling experiments confirmed that the oxygen atom in both L3-OH and Phim-CHO come from OOH. This aliphatic hydroxylation performed by 2 is in marked contrast to the arene hydroxylation reported for some (mu-1,1-hydroperoxo)dicopper(II) complexes with a xylyl linker.

Goto, M, Chikako, M, Hirayama, T, Terada, S, Nirengi, S, Kurosawa, Y, Nagano, A, and Hamaoka, T. Partial range of motion exercise is effective for facilitating muscle hypertrophy and function through sustained intramuscular hypoxia in young trained men. J Strength Cond Res 33(5): 1286–1294, 2019—The acute response to and long-term effects of partial range of motion exercise (PRE) and full range of motion exercise (FRE) of elbow extensors were compared in young trained men. The PRE was expected to increase the intramuscular hypoxic environment, which was theorized to enhance muscular hypertrophy. Forty-four resistance-trained men were divided into 2 training groups, PRE (n = 22) or FRE (n = 22) group, and performed the PRE or FRE acute exercise protocol. The PRE (elbow range from 45° to 90°) and FRE (from 0° to 120°) acute protocols consisted of 3 sets of 8 repetitions, with an 8RM, and an equivalent workload. After the initial testing, the training program for each group, comprised 3 training sessions per week for 8 weeks, was started. The acute responses of area under the oxygenated hemoglobin (Oxy-Hb) curve, blood lactate concentration, and root mean square of electromyography were significantly higher both before and after PRE than FRE training. Long-term effects were produced by both PRE and FRE, with significant (p ≤ 0.05) increases in cross-sectional area (CSA) of triceps brachii and isometric strength. The CSA increased significantly greater after PRE (48.7 ± 14.5%) than after FRE (28.2 ± 10.9%). Furthermore, during the PRE program, a positive correlation was detected between the percent increase in CSA and area under the Oxy-Hb curves before and after 8-week exercise training (before 8-week exercise training: r = 0.59, after 8-week exercise training: r = 0.70, p < 0.01). These results suggest that intramuscular hypoxia might facilitate muscular hypertrophy with PRE being more effective than FRE.

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The structure and dioxygen-reactivity of copper(I) complexes R supported by N,N-bis(6-methylpyridin-2-ylmethyl)amine tridentate ligands L2R[R (N-alkyl substituent)=-CH2Ph (Bn), -CH2CH2Ph (Phe) and -CH2CHPh2(PhePh)] have been examined and compared with those of copper(I) complex (Phe) of N,N-bis[2-(pyridin-2-yl)ethyl]amine tridentate ligand L1(Phe) and copper(I) complex (Phe) of N,N-bis(pyridin-2-ylmethyl)amine tridentate ligand L3(Phe). Copper(I) complexes (Phe) and (PhePh) exhibited a distorted trigonal pyramidal structure involving a d-pi interaction with an eta1-binding mode between the metal ion and one of the ortho-carbon atoms of the phenyl group of the N-alkyl substituent [-CH2CH2Ph (Phe) and -CH2CHPh2(PhePh)]. The strength of the d-pi interaction in (Phe) and (PhePh) was weaker than that of the d-pi interaction with an eta2-binding mode in (Phe) but stronger than that of the eta1 d-pi interaction in (Phe). Existence of a weak d-pi interaction in (Bn) in solution was also explored, but its binding mode was not clear. Redox potentials of the copper(I) complexes (E1/2) were also affected by the supporting ligand; the order of E1/2 was Phe>R>Phe. Thus, the order of electron-donor ability of the ligand is L1Phe

The authors clarified fine structures of Li-K edge of LiCoO2 reflecting core–hole effects, using monochromated transmission electron microscopy—electron energy-loss spectroscopy (TEM–EELS) and first-principles calculations. Variation of interband transitions into empty Co 3d states hybridized with O 2p states with decrease in x of LixCoO2 was also presented. A reduced peak of interband transitions at 3.2 eV in low-loss EELS spectrum with decrease in x was related to reduction in the original empty Co eg states for LiCoO2 and appearance of empty bands just below the eg band.