Sn O 2 nanowires synthesized by thermal evaporation method are investigated as a possible anode electrode for Li-ion batteries. In the first discharge process, the capacity of Li ions is 2133mAhg−1, which is much more than the theoretical total capacity of the bulk SnO2, 1494mAhg−1. During the successive 15cycles, the reversible capacity stays in the range of 1250–700mAhg−1 with a capacity fading of 3.89%percycle at a constant current density of 0.5mAcm−2. These results demonstrate that SnO2 nanowires are a promising anode material for Li-ion battery applications.

The effects of nanosized MnFe2O4 additive on the dehydrogenation properties of LiAlH4 prepared by ball milling were investigated for the first time. It was found that the LiAlH4 + 7 mol % MnFe2O4 sample started to decompose at 62 and 119 °C for the first two dehydrogenation stages and released 7.45 wt % hydrogen, which is 88 and 71 °C lower than those of as-received LiAlH4, respectively. The isothermal dehydriding kinetics show that the doped LiAlH4 sample could release about 4.7 wt % hydrogen in 70 min at 90 °C. Furthermore, the first two dehydrogenation steps could be finished within 80 min with 7.44 wt % hydrogen released at 120 °C, whereas as-received LiAlH4 only released about 0.5 wt % hydrogen for the same temperature and time. From differential scanning calorimetry (DSC) and Kissinger desorption kinetics analyses, the apparent activation energies, E a, of the doped sample were 66.7 kJ/mol for the first dehydrogenation stage and 75.8 kJ/mol for the second dehydrogenation stage, resulting in decreases of 40.2% and 58.1% compared with those of as-received LiAlH4, which are much higher than those of LiAlH4 doped with other reported catalysts calculated by Kissinger method. Through X-ray diffraction (XRD) and Fourier transform infrared (FTIR) observations, in situ formed Fe0.9536O and amorphous Mn or Mn-containing phases together provide a synergetic catalytic effect for the remarkably improved dehydrogenation properties of LiAlH4.

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Aqueous zinc-manganese dioxide (Zn-MnO2) batteries show great promise for grid-scale energy storage but suffer from sluggish reaction kinetics and severe structure instability of MnO2 cathode. Herein, a K+-pre-intercalated α-MnO2 cathode...

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BackgroundThe present study was conducted to investigate the possible association between gut microbes and immunity among healthy middle-aged and elderly individuals in southwest China. A total of 148 healthy adults aged ≥ 50 years were divided into two age groups: middle-aged group (50–59 years; n = 67, 54.13 ± 3.32) and elderly group (≥ 60 years; n = 81, 64.70 ± 3.93). Blood samples were collected to measure serum immune and biochemical indices. Gut microbiota compositions of the groups were characterized on the basis of faecal DNA using 16S rRNA gene sequencing.ResultsAmong the detected gut microbes, the presence of Alistipes was negatively correlated with age in both groups. In the middle-aged group, age was negatively correlated with the presence of Desulfovibrio and Faecalibacterium. In the elderly group, Coprococcus was present at significantly higher levels; age was negatively correlated with the presence of Lachnobacterium, Oxalobacter and the Chao index, whereas positively correlated with the presence of Sutterella. In the middle-aged group, the presence of Bacteroidetes was positively correlated with serum immunoglobulin G (IgG) levels and the percent of CD8+ T cells and negatively correlated with the CD4+/CD8+ ratio; the presence of Firmicutes was negatively correlated with IgM levels; Bacteroidetes/Firmicutes ratio was positively correlated with IgG and IgM levels and Simpson index was negatively correlated with the percent of CD8+ T cells and positively correlated with CD4+/CD8+ ratio. In the elderly group, the presence of Verrucomicrobia (identified as genus Akkermansia) was positively correlated with IgA levels and the percent of CD8+ T cells and negatively correlated with the percent of CD4+ T cells and CD4+/CD8+ ratio; the Chao index and observed species were positively correlated with IgA levels.ConclusionsThese results indicated that ageing could significantly correlate with the composition of gut microbiota in terms of quantity and quality. Changes in gut microbiota caused by ageing, characterized by decreased Bacteroidetes levels, might be associated with immunosenescence among healthy middle-aged and elderly people in southwest China.Electronic supplementary materialThe online version of this article (10.1186/s13099-018-0231-3) contains supplementary material, which is available to authorized users.

The catalytic effect of two nanoscale transition metal oxides, Fe 2 O 3 and Co 2 O 3 , as additives on the dehydrogenation properties of LiAlH 4 after milling are investigated. The onset dehydrogenation temperature for the 5 mol % Fe 2 O 3 -doped and 5 mol % Co 2 O 3 -doped samples are 85 and 79 °C lower for the first-stage and 60 and 45 °C lower for the second-stage, respectively, compared with the asreceived LiAlH 4 . The isothermal dehydriding kinetics reveals that the 5 mol % Fe 2 O 3 -doped sample can release about 7.1 wt % hydrogen in 70 min at 120 °C, whereas as-received LiAlH 4 only releases 0.3 wt % hydrogen under the same conditions. From differential scanning calorimetry (DSC) and Kissinger desorption kinetics analyses, the apparent activation energies (E a ) of the 5 mol % Fe 2 O 3 -doped sample are 54.2 and 86.4 kJ/mol for the first two dehydrogenation stages, resulting in decreases of 42.8 and 50% compared with those of as-received LiAlH 4 , respectively, which are considerably lowered compared with LiAlH 4 doped with other reported catalysts calculated by Kissinger method. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) analyses demonstrate that these finely dispersed Li 2 Fe 2.4 O 4.6 , Fe 0.957 O, and various Co oxides contribute to kinetics improvement by serving as active sites for nucleation and growth of dehydrogenated products.