Controlled actuation of soft objects with functional surfaces in aqueous environments presents opportunities for liquid phase electronics, novel assembled super-structures and unusual mechanical properties. We show the extraordinary electrochemically induced actuation of liquid metal droplets coated with nanoparticles, so-called "liquid metal marbles". We demonstrate that nanoparticle coatings of these marbles offer an extra dimension for affecting the bipolar electrochemically induced actuation. The nanoparticles can readily migrate along the surface of liquid metals, upon the application of electric fields, altering the capacitive behaviour and surface tension in a highly asymmetric fashion. Surprising actuation behaviours are observed illustrating that nanoparticle coatings can have a strong effect on the movement of these marbles. This significant novel phenomenon, combined with unique properties of liquid metal marbles, represents an exciting platform for enabling diverse applications that cannot be achieved using rigid metal beads.

We demonstrate photochemically induced actuation of liquid metal marbles, which are liquid metal droplets encased in micro/nanoparticles. The WO3 nanoparticles coated marbles are placed in H2O2 solution, and their surfaces are illuminated with UV light. The semiconducting WO3 coating behaves as a photocatalyst to trigger a photochemical reaction, generating oxygen bubbles that propel the marble. The actuation of the marbles is investigated under different H2O2 concentrations, light intensities, and marble dimensions. Equations describing the fundamentals of such actuations are presented.

To comprehensively identify proteins of liver plasma membrane (PM), we isolated PMs from mouse liver by sucrose density gradient centrifugation. An optimized extraction method for whole PM proteins and several methods of differential extraction expected to enrich hydrophobic membrane proteins were tested. The extracted PM proteins were separated by 2-DE, and were identified by MALDI-TOF-MS, and ESI-quadrupole-TOF MS. As the complementary method, 1-DE-MS/MS was also used to identify PM proteins. The optimized lysis buffer containing urea, thiourea, CHAPS and NP-40 was able to extract more PM proteins, and treatment of PM samples with chloroform/methanol and sodium carbonate led to enrichment of more hydrophobic PM proteins. From the mouse liver PM fraction, 175 non-redundant gene products were identified, of which 88 (about 50%) were integral membrane proteins with one to seven transmembrane domains. The remaining products were probably membrane-associated and cytosolic proteins. The function distribution of all the identified liver PM proteins was analyzed; 40% represented enzymes, 12% receptors and 9% proteins with unknown function.

Underwater wireless optical communication (UWOC) will play an important role in the underwater environment exploration and marine resource development due to its advantages of high data rate and good mobility. However, the significant signal power attenuation in the underwater channel limits the transmission distance of UWOC. Attenuation length (AL) is widely used as an indicator for evaluating the UWOC system's long-distance transmission capability. At present, Gbps UWOC is limited within 7AL. Using a SiPM based receiver can dramatically increase the AL that UWOC can support. In this paper, a novel UWOC receiver built from an off-the-shelf SiPM has been demonstrated. The finite pulse width and limited bandwidth of SiPM limit the SiPM based UWOC system's data rate. To boost the system's data rate, an optimum method to process the SiPM's signal has therefore been investigated. Based on these methods, the communication capabilities of the SiPM based UWOC have been investigated experimentally. Results show that the SiPM based receiver can support 11.6AL without turbulence and 9.28AL within weak turbulence (scintillation index = 0.0447) at 1 Gbps.

We show that partially trusting the phase noise associated with estimation uncertainty in a LLO-CVQKD system allows one to exchange higher secure key rates than in the case of untrusted phase noise. However, this opens a security loophole through the manipulation of the reference pulse amplitude. We label this as 'reference pulse attack' which is applicable to all LLO-CVQKD systems if the phase noise is trusted. We show that, at the optimal reference pulse intensity level, Eve achieves unity attack efficiency at 23.8km and 32.0km while using lossless and 0.14dB/km loss channels, respectively, for her attack. However, in order to maintain the performance enhancement from partially trusting the phase noise, countermeasures have been proposed. As a result, the LLO-CVQKD system with partially trusted phase noise owns a superior key rate at 20km by an order 9.5, and extended transmission distance by 45%, than that of the phase noise untrusted system.

In underwater optical wireless communication (UOWC) systems, using single photon avalanche photondiode (SPAD) as the detector can improve the transmission distance. However, the signal detection for SPAD-based systems is greatly challenged by the complex optical channel characteristics and SPAD nonlinear distortion. To address this issue, a novel deep learning aided signal detection scheme is proposed in this paper. By exploiting the physical mechanism and prior expert knowledge of the signal processing, a two-connected multilayer perception (MLP) network is integrated into the receiver. The first subnetwork is regarded as a channel compensation block while the second one works as a demodulator. With sophisticated numerical optical channel model and SPAD non-Poisson model, large amounts of training data are utilized to train the proposed model offline. Afterwards, the online data are recovered with the trained network. Simulation results verify that significant bit error ratio (BER) improvement can be achieved with the proposed scheme. INDEX TERMS Underwater optical wireless communication, nonlinear distortion, deep learning, multilayer perception, signal detection. I. INTRODUCTION With the application of technologies such as massive multi-input multi-output transmission, millimeter-wave (mm-mave) communication and non-orthogonal multiple access scheme, 5G mobile communication has significantly increased the system capacity and supported massive connections [1]. However, the 5G network is still ground based [2]. Vast communication demand at sea is greatly challenged due to the limited 5G network coverage. Thus, the envisaged 6G network is expected to provide global wireless connectivity from space to underwater. As a complementary technology for terrestrial communication, optical wireless communication, like laser communication or visible light The associate editor coordinating the review of this manuscript and approving it for publication was Zinan Wang .

The silicon photomultiplier (SiPM) based orthogonal frequency division multiplexing (OFDM) system is a promising solution to realize both the longer distance and higher data rate in visible light communication (VLC). However, it suffers from nonlinear distortions induced by SiPM. The Volterra nonlinear equalization (VNLE) is commonly used at the receiver to compensate for the nonlinear distortions, but it has a huge implementation complexity. As an alternative, the memory polynomial based equalization (MPE) offers significantly reduced complexity but at the cost of degrading BER performance. In this paper, we propose and demonstrate a promising simplified VNLE equalizer for SiPM based OFDM-VLC systems according to SiPM's characteristics. Results show that the proposed equalizer outperforms the MPE in terms of BER and significantly reduces the computational complexity of the conventional VNLE. With the proposed equalization scheme, a data rate of 1.35Gbps has been achieved. To the best of the author's knowledge, this is the highest data rate achieved using SiPM in VLC with optical OFDM.

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