Polyfluorene Conjugated Polyelectrolytes-Covalently Modified Black Phosphorus Nanosheets for Bioinspired Electronics.

As some of the most promising candidates for constituting bioinspired electronics, polymer memristors with analog-type switching behavior exhibit great potential for synaptic mimicking and neuromorphic computing systems. By using highly soluble conjugated polyelectrolyte poly[9,9-bis(6-(3-methyl-1-imidazolium-yl)hexyl)fluorene]-covalently modified black phosphorus (BP) nanomaterial (BP-PF-NMI+Br-) as the active layer, an electronic device with the BP-PF-NMI+Br- film sandwiched between the aluminum and indium tin oxide electrodes is successfully fabricated. This device exhibits an excellent amount of electricity-dependent memristive performance at a small sweep voltage range of ±1 V. With increasing amount of electricity flowing through the device, the device resistance gradually decreased in a linear pattern. The changes in frequency, amplitude, and duration of voltage pulses do not affect the linear relationship between the amount of electricity passing through the device and the resistance value achieved after each state reached equilibrium at different numbers of the same voltage pulse stimulations. Both the synaptic potentiation/depression and learning/memorizing/forgetting functions of biological systems have been emulated. In contrast to BP-PF-NMI+Br-, the pure PF-NMI+Br--based device shows a write-once-read-many-times effect at the same scanning voltage range, while the BP:PF-NMI+Br- blends exhibit very unstable memristive performances.

Redox-Active Azulene-based 2D Conjugated Covalent Organic Framework for Organic Memristors.

As a conjugated and unsymmetric building block composed of an electron-poor seven-membered sp2 carbon ring and an electron-rich five-membered carbon ring, azulene and its derivatives have been recognized as one of the most promising building blocks for novel electronic devices due to its intrinsic redox activity. By using 1,3,5-tris(4-aminophenyl)-benzene and azulene-1,3-dicarbaldehyde as the starting materials, an azulene(Azu)-based 2D conjugated covalent organic framework, COF-Azu, is prepared through liquid-liquid interface polymerization strategy for the first time. The as-fabricated Al/COF-Azu/indium tin oxide (ITO) memristor shows typical non-volatile resistive switching performance due to the electric filed induced intramolecular charge transfer effect. Associated with the unique memristive performance, a simple convolutional neural network is built for image recognition. After 8 epochs of training, image recognition accuracy of 80 % for a neutral network trained on a larger data set is achieved.

Water-Soluble Polythiophene-Conjugated Polyelectrolyte-Based Memristors for Transient Electronics.

The key to protect sensitive information stored in electronic memory devices from disclosure is to develop transient electronic devices that are capable of being destroyed quickly in an emergency. By using a highly water-soluble polythiophene-conjugated polyelectrolyte PTT-NMI+Br- as an active material, which was synthesized by the reaction of poly[thiophene-alt-4,4-bis(6-bromohexyl)-4H-cyclopenta(1,2-b:5,4-b')dithiophene] with N-methylimidazole, a flexible electronic device, Al/PTT-NMI+Br-/ITO-coated PET (ITO: indium tin oxide; PET: polyethylene terephthalate), is successfully fabricated. This device shows a typical nonvolatile rewritable resistive random access memory (RRAM) effect at a sweep voltage range of ±3 V and a history-dependent memristive switching performance at a small sweep voltage range of ±1 V. Both the learning/memorizing functions and the synaptic potentiation/depression of biological systems have been emulated. The switching mechanism for the PTT-NMI+Br--based electronic device may be highly associated with ion migration under bias. Once water is added to this device, it will be destructed rapidly within 20 s due to the dissolution of the active layer. This device is not only a typical transient device but can also be used for constructing conventional memristors with long-term stability after electronic packaging. Furthermore, the soluble active layer in the device can be easily recycled from its aqueous solution and reused for fabricating new transient memristors. This work offers a train of new thoughts for designing and constructing a neuromorphic computing system that can be quickly destroyed with water in the near future.

Donor-acceptor-type poly[chalcogenoviologen-alt-triphenylamine] for synaptic biomimicking and neuromorphic computing.

Polymer memristors are preeminent candidates for low-power edge computing paradigms. Poly[chalcogenoviologen-alt-triphenylamine] (PCVTPA) has been synthesized by direct coupling of chalcogeno-viologen as electron acceptor and 4-(bromomethyl)-N-(4-(bromo-methyl)phenyl)-N-phenylaniline as electron donor. The introduction of chalcogen atoms (S, Se, Te) into viologen scaffolds can greatly improve electrical conductive, electrochemical, and electrochromic properties of the materials when compared with the conventional viologens. Taking PTeVTPA as an example, the as-fabricated electronic device with a configuration of Al/PTeVTPA/ITO exhibits excellent multilevel storage and history-dependent memristive switching performance. Associated with the unique memristive behavior, the PTeVTPA-based device can not only be used to emulate the synaptic potentiation/depression, the human's learning and memorizing functions, and the transition from short-term synaptic plasticity to long-term plasticity but also carry out decimal arithmetic operations as well. This work will be expected to offer a train of new thought for constructing high-performance synaptic biomimicking and neuromorphic computing system in the near future.

Cavoatrial thrombectomy in hepatocellular carcinoma with tumor thrombus in the vena cava and atrium without the use of cardiopulmonary bypass.

BACKGROUND: Hepatocellular carcinoma (HCC) with tumor thrombus (TT) in hepatic vein, inferior vena cava (IVC), and right atrium (RA) portends a poor prognosis because of intravascular extension leading to rapid distal metastases. En bloc resection of cavoatrial TT without the use of cardiopulmonary bypass (CPB) is challenging. We describe a new method of vascular occlusion for thrombus entering into the RA without the need for CPB as shown in echocardiography. METHODS AND RESULTS: Retrospective analysis was carried out in 1 HCC patient, who had undergone hepatectomy with TT extension into IVC and RA. The infrahepatic IVC was occluded with vascular tape and the right atrial appendage was controlled with a Satinsky clamp proximal to the TT. The IVC wall was incised under direct vision from the infrahepatic IVC cranially. The tumor and thrombus were then removed en bloc under direct vision. Thus, cavoatrial thrombectomy was performed under total hepatic vascular exclusion without the use of CPB. He survived for 6 months and died of tumor recurrence. CONCLUSIONS: Using this technique, advanced HCC with cavoatrial TT can be resected safely without CPB and thereby avoid dislodgement of TT and air embolism.