NPC

Xiaoli Jiang, Haeseong Jang, Shang-Guo Liu, Zi-Jian Li, Min Gyu Kim, Chuang Li, Qing Qin, Xien Liu, Jaephil Cho

Facilitating the dissociation of water and desorption of hydrogen are both crucial challenges for improving the hydrogen evolution reaction (HER) in alkaline media. Herein, we report the synthesis of heterostructure of Ru2P/WO3@NPC (N, P co-doped carbon) by a simple hydrothermal reaction using ruthenium and tungsten salts as precursors, followed by pyrolyzing under an Ar atmosphere. The Ru2P/WO3@NPC electrocatalyst exhibits an outstanding HER activity with an overpotential of 15 mV at a current density of 10 mA·cm-2 and excellent durability in a 1.0 M KOH solution, outperforming state-of-the-art Pt/C and most reported electrocatalysts. Experimental results combined with density functional theory calculations reveal that the electron density redistribution in Ru2P/WO3@NPC is achieved by electron transfer from NPC to Ru2P/WO3 and from Ru2P to WO3, which directly promotes the dissociation of water on W sites in WO3 and desorption of hydrogen on Ru sites in Ru2P.

Yan Wang, Xiaochuang Di, Zhao Lu, Xin-Ming Wu

Nowadays, electromagnetic (EM) radiation poses severe environmental pollution and harm to civilian and military life. To this end, it is urgent to synthesize high-efficiency microwave absorbers in terms of composition and structural design. Herein, we reported a unique hybrid nanostructure with Co particles embedded in hollow carbon polyhedron by a series of synthetic steps including carbonization and pyrolysis. Further, the nanoporous carbon (NPC) derived from wheat flour is coated onto the surface of Co@C polyhedrons, forming a special hierarchical structure (Co@C@NPC), which demonstrates outstanding microwave absorption properties due to the hierarchical porous structure, enhanced interfacial polarization, conduction loss, multi-reflection and matched impedance. Typically, with a 10 wt% filler content, the maximum RL of Co@C@NPC reaches -57.2 dB at 9.6 GHz and the corresponding effective bandwidth is 5.7 GHz (from 7.5 to 13.2 GHz) with an absorber thickness of 3 mm. Besides, the filler loading of 10 wt% is much lower than other reported bio-derived absorbers. In short, the hybrid zeolitic imidazolate frameworks offer a novel idea for constructing hollow carbon skeletons and introducing biomass carbon as a green, low cost and renewable material that enhances the dielectric loss and the synergistic effect between permittivity and permeability.

Qian-Qian Cai, Teng Yin, Yuhang Ye, Gui-Fen Jie, Hong Zhou

Eliminating false positives or negatives in analysis has been a challenge. Herein, a phenomenon of polarity-switching photocurrent of AgInS2 quantum dot (QD)-DNA nanowires reversing nitrogen-doped porous carbon-ZnO (NPC-ZnO) nanopolyhedra was found for the first time, and a versatile photoelectrochemical (PEC) biosensor with a reversed signal was innovatively proposed for dual-target detection. NPC-ZnO is a photoactive material with excellent PEC properties, while AgInS2 QDs as a photosensitive material match NPC-ZnO in the energy level, which not only promotes the transfer of photogenerated carriers but also switches the direction of PEC current. Furthermore, in order to prevent spontaneous agglomeration of AgInS2 (AIS) QDs and improve its utilization rate, a new multiple-branched DNA nanowire was specially designed to assemble AgInS2 QDs for constructing amplified signal probes, which not only greatly increased the load of AgInS2 QDs but also further enhanced the photoelectric signal. When the target Hg2+-induced cyclic amplification process generated abundant RDNA, the DNA nanowire signal probe with plenty of QDs was linked to the NPC-ZnO/electrode by RDNA, generating greatly amplified polarity-reversed photocurrent for signal "ON" detection of Hg2+. After specific binding of the target (aflatoxin B1, AFB1) to its aptamer, the signal probes of AIS QD-DNA nanowires were released, realizing signal "OFF" assay of AFB1. Thus, the proposed new PEC biosensor provides a versatile method for detection of dual targets and also effectively avoids both false positive and negative phenomena in the assay process, which has great practical application potential in both environmental and food analysis.

Xiao-Ning Shen, Jian-Xing Liu, Guang-Xin Liu, Jianhua Zhang, José I. Leon, Li-Gang Wu, L. Franquelo

In this paper, a generalized proportional integral observer (GPIO)-based finite-time sliding mode control scheme is proposed to enhance the convergence rate and disturbance rejection capacity of the grid-connected three-level neutral-point-clamped (NPC) converter. Firstly, a generalized super-twisting algorithm (GSTA) is designed in the voltage regulation loop and the instantaneous power loop of the NPC converter. Compared with the conventional super-twisting algorithm (STA), this method provides a faster convergence speed while the system trajectories are far from the origin, which is applied to the NPC converter to improve its dynamic performance and robustness. Additionally, by introducing a generalized proportional integral observer (GPIO) combined with the GSTA in the voltage regulation loop, the unknown time-varying disturbances can be rejected effectively. The stability of the proposed control scheme is proved. Finally, a set of comparative experiments between the proposed controller and the classic STA-based method have been carried out based on a three-level NPC converter prototype, and the results confirmed the efficacy of the proposed control strategy.

M. Las Heras, Benjamín Szenfeld, Rami A Ballout, E. Buratti, S. Zanlungo, A. Dardis, A. Klein

Niemann-Pick type C (NPC) disease is a lysosomal storage disease (LSD) characterized by the buildup of endo-lysosomal cholesterol and glycosphingolipids due to loss of function mutations in the NPC1 and NPC2 genes. NPC patients can present with a broad phenotypic spectrum, with differences at the age of onset, rate of progression, severity, organs involved, effects on the central nervous system, and even response to pharmacological treatments. This article reviews the phenotypic variation of NPC and discusses its possible causes, such as the remaining function of the defective protein, modifier genes, sex, environmental cues, and splicing factors, among others. We propose that these factors should be considered when designing or repurposing treatments for this disease. Despite its seeming complexity, this proposition is not far-fetched, considering the expanding interest in precision medicine and easier access to multi-omics technologies.