We report a facile approach to produce lightweight microcellular polyetherimide (PEI)/graphene nanocomposite foams with a density of about 0.3 g/cm3 by a phase separation process. It was observed that the strong extensional flow generated during cell growth induced the enrichment and orientation of graphene on cell walls. This action decreased the electrical conductivity percolation from 0.21 vol % for PEI/graphene nanocomposite to 0.18 vol % for PEI/graphene foam. Furthermore, the foaming process significantly increased the specific electromagnetic interference (EMI) shielding effectiveness from 17 to 44 dB/(g/cm3). In addition, PEI/graphene nanocomposite foams possessed low thermal conductivity of 0.065-0.037 W/m·K even at 200 °C and high Young's modulus of 180-290 MPa.

As the portable device hardware has been increasing at a noticeable rate, ultrathin thermal conducting materials (TCMs) with the combination of high thermal conductivity and excellent electromagnetic interface (EMI) shielding performance, which are used to effi ciently dissipate heat and minimize EMI problems generated from electronic components (such as high speed processors), are urgently needed. In this work, graphene oxide (GO) fi lms are fabricated by direct evaporation of GO suspension under mild heating, and ultrathin graphite-like graphene fi lms are produced by graphitizing GO fi lms. Further investigation demonstrates that the resulting graphene fi lm with only ≈8.4 µm in thickness not only possesses excellent EMI shielding effectiveness of ≈20 dB and high in-plane thermal conductivity of ≈1100 W m −1 K −1 , but also shows excellent mechanical fl exibility and structure integrity during bending, indicating that the graphitization of GO fi lm could be considered as a new alternative way to produce excellent TCMs with effi cient EMI shielding.

Novel high-performance polyetherimide (PEI)/graphene@Fe3O4 (G@Fe3O4) composite foams with flexible character and low density of about 0.28-0.4 g/cm(3) have been developed by using a phase separation method. The obtained PEI/G@Fe3O4 foam with G@Fe3O4 loading of 10 wt % exhibited excellent specific EMI shielding effectiveness (EMI SE) of ~41.5 dB/(g/cm(3)) at 8-12 GHz. Moreover, most the applied microwave was verified to be absorbed rather than being reflected back, resulting from the improved impedance matching, electromagnetic wave attenuation, as well as multiple reflections. Meanwhile, the resulting foams also possessed a superparamagnetic behavior and low thermal conductiviy of 0.042-0.071 W/(m K). This technique is fast, highly reproducible, and scalable, which may facilitate the commercialization of such composite foams and generalize the use of them as EMI shielding materials in the fields of spacecraft and aircraft.

The fabrication of low-density and compressible polymer/graphene composite (PGC) foams for adjustable electromagnetic interference (EMI) shielding remains a daunting challenge. Herein, ultralightweight and compressible PGC foams have been developed by simple solution dip-coating of graphene on commercial polyurethane (PU) sponges with highly porous network structure. The resultant PU/graphene (PUG) foams had a density as low as ∼0.027-0.030 g/cm(3) and possessed good comprehensive EMI shielding performance together with an absorption-dominant mechanism, possibly due to both conductive dissipation and multiple reflections and scattering of EM waves by the inside 3D conductive graphene network. Moreover, by taking advantage of their remarkable compressibility, the shielding performance of the PUG foams could be simply adjusted through a simple mechanical compression, showing promise for adjustable EMI shielding. We believe that the strategy for fabricating PGC foams through a simple dip-coating method could potentially promote the large-scale production of lightweight foam materials for EMI shielding.

Cases of convergent evolution - where different lineages have evolved similar traits independently - are common and have proven central to our understanding of selection. Yet convincing examples of adaptive convergence at the sequence level are exceptionally rare [1]. The motor protein Prestin is expressed in mammalian outer hair cells (OHCs) and is thought to confer high frequency sensitivity and selectivity in the mammalian auditory system [2]. We previously reported that the Prestin gene has undergone sequence convergence among unrelated lineages of echolocating bat [3]. Here we report that this gene has also undergone convergent amino acid substitutions in echolocating dolphins, which group with echolocating bats in a phylogenetic tree of Prestin. Furthermore, we find evidence that these changes were driven by natural selection.

As an important reactive oxygen species (ROS) with selective oxidation, singlet oxygen ( 1 O 2 ) has wide application prospects in biology and the environment. However, the mechanism of 1 O 2 formation, especially the conversion of superoxide radicals (•O 2 − ) to 1 O 2 , has been a great controversy. This process is often disturbed by hydroxyl radicals (•OH). Here, we develop a molybdenum cocatalytic Fenton system, which can realize the transformation from •O 2 − to 1 O 2 on the premise of minimizing • OH. The Mo 0 exposed on the surface of molybdenum powder can significantly improve the Fe 3+ /Fe 2+ cycling efficiency and weaken the production of •OH, leading to the generation of •O 2 − . Meanwhile, the exposed Mo 6+ can realize the transformation ofThe molybdenum cocatalytic effect makes the conventional Fenton reaction have high oxidation activity for the remediation of organic pollutants and prompts the inactivation of Staphylococcus aureus, as well as the adsorption and reduction of heavy metal ions (Cu 2+ , Ni 2+ , and Cr 6+ ). Compared with iron powder, molybdenum powder is more likely to promote the conversion from Fe 3+ to Fe 2+ during the Fenton reaction, resulting in a higher Fe 2+ /Fe 3+ ratio and better activity regarding the remediation of organics. Our findings clarify the transformation mechanism from •O 2 − to 1 O 2 during the Fenton-like reaction and provide a promising REDOX Fenton-like system for water treatment.

Plasmonic MoO3-x@MoO3 nanosheets obtained from surface oxidation of MoO3-x were employed as a SERS substrate for methylene blue detection. They exhibit extraordinary sensitivity comparable to noble metals, which is attributed to shell-isolated electromagnetic enhancing by the plasmonic MoO3-x core and elimination of the photocatalytic degradation by the MoO3 shell.

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