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Electrochemical properties of core/branch-structured VS2 nanosheets@CNTs and the in situ investigation of the corresponding dynamic structural evolutions.

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Design and synthesis of new carbon allotropes have always been important topics in condensed matter physics and materials science. Here we report a new carbon allotrope, formed from cold-compressed C_{70} peapods, which most likely can be identified with a fully sp^{3}-bonded monoclinic structure, here named V carbon, predicted from our simulation. The simulated x-ray diffraction pattern, near K-edge spectroscopy, and phonon spectrum agree well with our experimental data. Theoretical calculations reveal that V carbon has a Vickers hardness of 90 GPa and a bulk modulus ∼400  GPa, which well explains the "ring crack" left on the diamond anvils by the transformed phase in our experiments. The V carbon is thermodynamically stable over a wide pressure range up to 100 GPa, suggesting that once V carbon forms, it is stable and can be recovered to ambient conditions. A transition pathway from peapod to V carbon has also been suggested. These findings suggest a new strategy for creating new sp^{3}-hybridized carbon structures by using fullerene@nanotubes carbon precursor containing odd-numbered rings in the structures.

Background The evidence of the association between Chinese visceral adiposity index (CVAI) and risk of type 2 diabetes mellitus (T2DM) is limited. We explored the association of CVAI with T2DM and directly compared with the predictive power of CVAI with other visceral obesity indices (visceral adiposity index, waist to height ratio, waist circumference and body mass index) based on a large prospective study. Methods We conducted a population‐based study of 12 237 Chinese participants. Cox proportional‐hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between CVAI and T2DM. Results During follow‐up (median: 6.01 years), the incidence of T2DM was 3.29, 7.34, 12.37 and 23.72 per 1000 person‐years for quartiles 1, 2, 3 and 4 of CVAI, respectively. The risk of T2DM was increased with quartiles 2, 3 and 4 vs quartile 1 of CVAI (HR 2.12 [95% CI 1.50‐3.00], 2.94 [2.10‐4.13] and 5.01 [3.57‐7.04], Ptrend < 0.001). Per‐SD increase in CVAI was associated with a 72% increased risk of T2DM (HR 1.72 [95% CI 1.56‐1.88]). Sensitivity analyses did not alter the association. The area under receiver operating characteristic curve was significantly higher for CVAI than other visceral obesity indices (all P <.001). Similar results were observed in stratified analyses by sex. Conclusions Our findings show a positive association between CVAI and risk of T2DM. CVAI has the best performance in predicting incident T2DM, so the index might be a reliable and applicable indicator identifying people at high risk of T2DM.

A strategy for preparing hybrid carbon structures with amorphous carbon clusters as hard building blocks by compressing a series of predesigned two-component fullerides is presented. In such constructed structures the building blocks and their boundaries can be tuned by changing the starting components, providing a way for the creation of new hard/superhard materials with desirable properties.

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