performance and relatively low cost have been demonstrated as a leading candidate for numerous applications in energy harvesting and self-powered sensing. [1][2][3][4][5] It plays an increasingly important role with the fast depletion of fossil fuels. As an energy harvester, the output characteristic of the TENGs is the key consideration, which involves two main aspects: the surface charge density [6][7][8] and the output impedance. [9,10] Till now, studies have been conducted on the improvement of the surface charge density, such as surface functionalization techniques including micropatterning surface, [11][12][13][14][15][16][17][18][19][20] plasma treatment, [21] or adding chemical functional groups. [22][23][24][25] Especially substantial researches on the TENGs have concentrated on making triboelectric layers into both micro-and nanoscale to achieve increased surface areas and roughness. [26] However, there is a lack of effective means to reduce the output impedance.Plasmonic energy conversion proposed as a high efficiency scheme to electron-hole separation opens up a wide range of applications in the field of subwavelength optics, [27] data storage, [28] nonlinear optics, [29] solar cells, [30] and Adv. Energy Mater. 2019, 9, 1902725 www.advenergymat.de www.advancedsciencenews.com

In this paper, we describe three-dimensional (3D) hierarchical graphene-hydroxyapatite hybrid bioscaffolds (GHBs) with a calcium phosphate salt electrochemically deposited onto the framework of graphene foam (GF). The morphology of the hydroxyapatite (HA) coverage over GF was controlled by the deposition conditions, including temperature and voltage. The HA obtained at the higher temperature demonstrates the more uniformly distributed crystal grain with the smaller size. The as-prepared GHBs show a high elasticity with recoverable compressive strain up to 80%, and significantly enhanced strength with Young's modulus up to 0.933 MPa compared with that of pure GF template (~7.5 kPa). Moreover, co-culture with MC3T3-E1 cells reveals that the GHBs can more effectively promote the proliferation of MC3T3-E1 osteoblasts with good biocompatibility than pure GF and the control group. The superior performance of GHBs suggests their promising applications as multifunctional materials for the repair and regeneration of bone defects.

As a promising renewable energy source, it is a challenging task to obtain blue energy, which is irregular and has an ultralow frequency, due to the limitation of technology. Herein, a nonresonant hybridized electromagnetic-triboelectric nanogenerator was presented to efficiently obtain the ultralow frequency energy. The instrument adopted the flexible pendulum structure with a precise design and combined the working principle of electromagnetism and triboelectricity to realize the all-directional vibration energy acquisition successfully. The results confirmed that the triboelectric nanogenerator (TENG) had the potential to deliver the maximum power point of about 470 μW while the electromagnetic nanogenerator (EMG) can provide 523 mW at most. The conversion efficiency of energy of the system reached 48.48%, which exhibited a remarkable improvement by about 2.96 times, due to the elastic buffering effect of the TENG with the double helix structure. Furthermore, its ability to collect low frequency wave energy was successfully proven by a buoy in Jialing River. This woke provides an effective candidate to harvest irregular and ultralow frequency blue energy on a large scale.

In order to study the in uence of rotational speed and amplitude on the surface integrity, TC18 titanium alloy samples were milled by the process of conventional milling and longitudinal ultrasonic vibration assisted milling. The experimental data were obtained by dynamometer, thermometer, scanning electron microscope, X-ray diffractometer and three-dimensional surface topography instrument for observation and analysis. The results show that the rotational speed has a signi cant effect on the cutting force, cutting temperature, surface morphology and surface residual stress. Compared with ordinary milling, the surface micro-texture produced by ultrasonic vibration milling is more regular, , and with the increase of rotational speed, the in uence of ultrasonic vibration on cutting force and cutting temperature decrease.There are adverse effects on surface roughness after ultrasonic vibration superposition. The in uence of ultrasonic vibration on the surface residual compressive stress is also greatly reduced when the rotational speed is greater than 2400 rpm. In addition, a certain depth of plastic deformation layer can be formed under the surface of ultrasonic vibration machining, and the depth of deformation layer increases with the increase of vibration.