Ultraflexible Ultrathin 3D/1D Hierarchical Interpenetrating Ni-MOF/CNT Buckypaper Composites: Microstructures and Microwave Absorption Properties.

Metal-organic frameworks (MOFs) have attracted attention due to their designable structures. However, recently reported MOF microwave-absorbing materials (MAMs) are dominated by powders. It remains a challenge to design MOF/carbon nanotube (CNT) composite structures that combine the mechanical properties of self-supporting flexibility with excellent microwave absorption. This work involves the hydrothermal approach to grow Ni-MOF of different microstructures in situ on the CNT monofilament by adjusting the molar ratio of nickel ions to organic ligands. Subsequently, an ultraflexible self-supporting Ni-MOF/CNT buckypaper (BP) is obtained by directional gas pressure filtration technology. The BP porous skeleton and the Ni-MOF with a unique porous structure provide effective impedance matching. The CNTs contribute to the conduction loss, the cross-scale heterogeneous interface generated by Ni-MOF/CNT BP provides rich interfacial polarization loss, and the porous structure complicates the microwave propagation path. All factors work together to give Ni-MOF/CNT BP an excellent microwave absorption capacity. The minimum reflection losses of Ni-MOF/CNT BPs decorated with granular-, hollow porous prism-, and porous prism-shaped Ni-MOFs reach -50.8, -57.8, and -43.3 dB, respectively. The corresponding effective absorption bandwidths are 4.5, 6.3, and 4.8 GHz, respectively. Furthermore, BPs show remarkable flexibility as they can be wound hundreds of times around a glass rod with a diameter of 4 mm without structural damage. This work presents a new concept for creating ultraflexible self-supported MOF-based MAMs with hierarchical interpenetrating porous structures, with potential application advantages in the field of flexible electronics.

Synthesis and Electromagnetic Interference Shielding Performance of Ti3SiC2-Based Ceramics Fabricated by Liquid Silicon Infiltration.

In this work, Ti3SiC2-based ceramics were fabricated by the infiltration of liquid silicon into TiC preform by incorporating a small amount of Al. Al can play a catalytic role to promote the formation of TiC twins before liquid silicon infiltration (LSI), which leads to the increase of transformation efficiency from TiC to Ti3SiC2 in the LSI process. When the Al content in the TiC preform increases to 9 wt.%, the volume content of Ti3SiC2 reaches 85 vol.%, revealing the high electromagnetic interference shielding effectiveness of 39 dB in the frequency range of 8.2-12.4 GHz. The results indicate that it is an effective way to synthesize Ti3SiC2-based ceramics with excellent electromagnetic shielding performance.

Fabrication of TiO2 Nanostructures on Ti3SiC2 Substrate by Anodic Oxidation.

A TiO2 nanostructure was prepared on a Ti3SiC2 substrate with different water and NH4F concentrations in a fluoride-containing ethylene glycol electrolyte via an anodization process using the same constant-anodization potentials, anodization duration and temperature. The as-prepared samples were characterized by a field-emission scanning electron microscope equipped with an energy dispersive X-ray spectroscope, as well as by X-ray diffraction and X-ray photoelectron spectroscopy. The influence of the anodizing parameters and annealing temperature on the morphology of the nanostructure and the phase structure was studied. The results showed that the scattered TiO2 nanotubes and TiO2 nanoporous films were successfully fabricated in the glycol electrolyte containing (3.0 wt%) NH4F +(5.0 vol%) H2O. The as-prepared samples before calcination were amorphous and could transform to the anatase phase at temperatures higher than 500 °C. As the annealing temperature increased, the crystallization of the anatase phase was enhanced, and the rutile phase appeared at 600 °C. The as-prepared samples mainly consisted of oxides. Ti2O3 and SiO2 oxides were present in addition to TiO2.

The quality of life and mortality risk of elderly people in rural China: the role of family support.

The number of elderly in China's population is projected to grow well beyond the capacity of the nation's social security system. Meanwhile, family care is being challenged by a decline in fertility and an increase in migration from rural to urban areas. This article examines the short-term, mid-term, and long-term effects of family support on elderly well-being in rural China, using 4-wave panel data on 1456 persons aged 60 and older in the Chaohu region of China. Findings showed that compared with living alone, being coresident with others lowered the mortality risk of several chronic diseases, but being coresident with adult children increased the mortality risk of cardiovascular diseases, though it was associated with a higher quality of life in the short and middle terms. Children's educational attainment and financial support increased the quality of life except for an increased risk of new incidence of cardiovascular disease in the middle term.

[Contralateral suppressions of transient evoked otoacoustic emissions in diabetes mellitus patients].

OBJECTIVE: To investigate the contralateral suppressions of transient evoked otoacoustic emissions (TEOAE) in diabetes mellitus patients with normal hearing. METHOD: The pure tone audiometry, acoustic immittance and TEOAE tests were performed in 30 diabetes mellitus patients with normal hearing and 30 healthy controls. The efferent system functions were evaluated by contralateral suppression of TEOAE. RESULT: There were no significant differences of pure tone thresholds and amplitudes of TEOAE between the two groups. The contralateral suppressions of TEOAE in diabetes mellitus patients were significantly lower than that in controls (P<0.05 at 2000 and 4000 Hz respectively). CONCLUSION: The nerve functions of central nerve system can be damaged in diabetes mellitus patients with normal hearing.