Computational design of bimetallic Tm_(2)@g-C_(9)N_(4)electrocatalysts for enhanced CO reduction toward C_(2)products

Electrochemical CO reduction(ECOR)as a potential strategy for producing valuable chemicals and fuels has captured substantial attention.However,the currently available electrocatalysts suffer from poor selectivity and low Faradaic efficiency,limiting their industrial application.Herein,we systematically investigate the potential of homonuclear bimetallic electrocatalysts,Tm_(2)@C_(9)N_(4)(TM=Fe,Co,Ni,and Cu),for the ECOR through extensive density functional theory calculations.Our findings suggest that all four proposed monolayers exhibit exceptional stability,making them highly suitable for experimental synthesis and practical applications.Interestingly,these transition-metal dual atoms anchored on C_(9)N_(4)monolayers show great potential in facilitating the production of high-value C_(2)products,such as C_(2)H_(5)OH and C_(2)H_(4),due to the significantly low limiting potentials(-0.06~-0.46 V)and small kinetic energy barriers(0.54–1.08 eV)for the CO coupling process.Moreover,with the exception of Ni_(2)@C_(9)N_(4),these bimetallic catalysts demonstrate the impressive suppression of the competitive hydrogen evolution reaction(HER),leading to a high selectivity for C_(2)products in ECOR.Our predictions would accelerate the development of high-performance C_(9)N_(4)-based dual-atom catalysts for the ECOR.

Expansion Strategy-Driven Micron-Level Resolution Mass Spectrometry Imaging of Lipids in Mouse Brain Tissue

A novel method for enhanced resolution,termed expansion mass spectrometry imaging,has been developed for lipid mass spectrometry imaging,utilizing existing commercially available mass spectrometers without necessitating modifications.This approach involves embedding tissue sections in a swellable polyelectrolyte gel,with the target biomolecules indirectly anchored to the gel network.By employing matrix-assisted laser desorption ionization mass spectrometry imaging,the method has realized an enhanced spatial resolution that surpasses the conventional resolution limits of commercial instruments by approximately 4.5 fold.This enhancement permits the detailed visualization of intricate structures within the mouse brain at a subcellular level,with a lateral resolution nearing 1μm.As a physical technique for achieving resolution beyond standard capabilities,this readily adaptable approach presents a powerful tool for high-definition imaging in biological research.

High-responsivity on-chip waveguide coupled germanium photodetector for 2 μm waveband

Recently,the emerging 2μm waveband has gained increasing interest due to its great potential for a wide scope of applications.Compared with the existing optical communication windows at shorter wavelengths,it also offers distinct advantages of lower nonlinear absorption,better fabrication tolerance,and larger free carrier plasma effects for silicon photonics,which has been a proven device technology.While much progress has been witnessed for silicon photonics at the 2μm waveband,the primary challenge still exists for on-chip detectors.Despite the maturity and compatibility of the waveguide coupled photodetectors made of germanium,the 2μm regime is far beyond its cutoff wavelength.In this work,we demonstrate an efficient and high-speed on-chip waveguidecoupled germanium photodetector operating at the 2μm waveband.The weak sub-bandgap absorption of epitaxial germanium is greatly enhanced by a lateral separation absorption charge multiplication structure.The detector is fabricated by the standard process offered by a commercial foundry.The device has a benchmark performance with responsivity of 1.05 A/W and 3 dB bandwidth of 7.12 GHz,which is able to receive high-speed signals with up to 20 Gbit/s data rate.The availability of such an efficient and fast on-chip detector circumvents the barriers between silicon photonic integrated circuits and the potential applications at the 2μm waveband.

功能型聚合物基电磁屏蔽材料的制备及应用

随着大功率电子设备和电子通信技术的快速发展,如新兴的5G移动网络通信技术,开发高性能电磁干扰屏蔽材料已成为迫切的需求。聚合物基电磁屏蔽材料(PEMSM)由于其重量轻、可加工性强和电导率可调节等方面的优势而得到了长足的发展。日益复杂的应用环境和使用条件对PEMSM的功能性提出了更高的要求。本文首先讨论了电磁屏蔽的关键概念和损耗机制(反射、吸收和多次反射);其次总结了目前PEMSM的结构,包括均质结构、隔离结构、多孔结构和层状结构等,其中均质结构加工流程简单,隔离结构可降低材料的导电逾渗阈值,多孔结构有助于电磁波的多次反射和吸收,层状结构可以使电磁波在材料内部多次反射;然后详细介绍了功能型PEMSM的研究进展,涉及的功能包括耐久性、超疏水、抗菌性和电热性等;最后对功能性PEMSM的发展趋势进行了展望。

Hybrid nanogenerator based closed-loop self-powered low-level vagus nerve stimulation system for atrial fibrillation treatment

Atrial fibrillation is an “invisible killer” of human health. It often induces high-risk diseases, such as myocardial infarction, stroke, and heart failure. Fortunately, atrial fibrillation can be diagnosed and treated early. Low-level vagus nerve stimulation(LL-VNS) is a promising therapeutic method for atrial fibrillation. However, some fundamental challenges still need to be overcome in terms of flexibility,miniaturization, and long-term service of bioelectric stimulation devices. Here, we designed a closedloop self-powered LL-VNS system that can monitor the patient’s pulse wave status in real time and conduct stimulation impulses automatically during the development of atrial fibrillation. The implant is a hybrid nanogenerator(H-NG), which is flexible, light weight, and simple, even without electronic circuits,components, and batteries. The maximum output of the H-NG was 14.8 V and 17.8 μA(peak to peak). In the in vivo effect verification study, the atrial fibrillation duration significantly decreased by 90% after LLVNS therapy, and myocardial fibrosis and atrial connexin levels were effectively improved. Notably, the anti-inflammatory effect triggered by mediating the NF-κB and AP-1 pathways in our therapeutic system is observed. Overall, this implantable bioelectronic device is expected to be used for self-powerability,intelligentization, portability for management, and therapy of chronic diseases.

Oxygen microcapsules improve immune checkpoint blockade by ameliorating hypoxia condition in pancreatic ductal adenocarcinoma

Rationale:Hypoxia in tumor microenvironment(TME)represents an obstacle to the efficacy of immunotherapy for pancreatic ductal adenocarcinoma(PDAC)through several aspects such as increasing the expression of immune checkpoints or promoting fibrosis.Reversing hypoxic TME is a potential strategy to improve the validity of immune checkpoint blockade(ICB).Methods:Here,we synthesized polydopamine-nanoparticle-stabilized oxygen microcapsules with excellent stabilization,bioavailability,and biocompatibility for direct oxygen delivery into tumor sites by interfacial polymerization.Results:We observed oxygen microcapsules enhanced the oxygen concentration in the hypoxia environment and maintained the oxygen concentration for a long period both in vitro and in vivo.We found that oxygen microcapsules could significantly improve the efficiency of ICB against PDAC in vivo.Mechanismly,combined treatments using oxygen microcapsules and ICB could reduce the infiltration of tumor-associated macrophages(TAMs)and polarized pro-tumor M2 macrophages into anti-tumor M1 macrophages.In addition,combined treatments could elevate the proportion of T helper subtype 1 cells(Th1 cells)and cytotoxic T lymphocytes cells(CTLs)to mediate anti-tumor immune response in TME.Conclusion:In summary,this pre-clinical study indicated that reversing hypoxia in TME by using oxygen microcapsules was an effective strategy to improve the performances of ICB on PDAC,which holds great potential for treating PDAC in the future.

Effect of multiphase content on temperature-dependent electrical conductivity in silicone rubber composites

To investigate how the multiphase structures affect the electrical conductivity in semicrystalline polymer composites,herein,an accurate multiphase content calculation method is proposed and verified,which combines amorphous phase information in broadband dielectric spectroscopy and crystalline phase information in differential scanning calorimetry.Taken aluminium hydroxide(ATH)filled silicone rubber as an example,it is found that the rigid amorphous fraction(RAF)corresponding to the chains constrained by crystals(RAF_(cry))is not linearly increased with crystalline fraction(CF).Compared to non-isothermal crystallisation,RAF caused by ATH/silicone rubber interface(RAF_(int))after isothermal crystallisation at 213 K changes little,while mobile amorphous fraction and RAFcry is attenuated and CF is strengthened.Based on the calculated structures of ATH filled silicone rubber,activation energy of conductivities during cooling is dominated by the thermal transition for conductive ions and shortened distance among the conductive ions through shrunk volumes of the amorphous phase.Our findings deepen the understanding of multiphase content in semi-crystalline polymer composites and its relationship with electrical conductivity,which can be applied in manipulating electrical performance of semi-crystalline polymers by fillers.

通过不同退火路径获得相同的玻璃态

本文以金基金属玻璃为模型,使用高精度闪速差示扫描量热法研究了等温退火和连续降温退火对焓弛豫和回复过程的影响.发现即使玻璃的能量(焓)一样,两种退火路径获得的玻璃的状态也可能不同.对于短时间等温退火或快速连续降温退火得到的高能量玻璃,两种退火路径获得的玻璃状态明显不同:连续降温退火得到的玻璃的弛豫峰更窄,而等温退火得到的玻璃弛豫峰更宽.但是,对于长时间等温退火或慢速连续降温退火得到的低能量玻璃,两种退火路径获得的玻璃状态趋于相同,即弛豫峰完全重合.弛豫动力学结果表明,高能量玻璃处在β弛豫阶段,具有热历史依赖性.而低能量玻璃处在α弛豫阶段,玻璃状态与热历史无关,这主要是因为α弛豫具有较强的协同性,具有各态遍历特征,使结构均一化.这些发现对精准调控玻璃性质具有重要意义.

Multicellular tumor spheroids bridge the gap between two-dimensional cancer cells and solid tumors: The role of lipid metabolism and distribution

Previous studies demonstrated that three-dimensional(3D) multicellular tumor spheroids(MCTS) could more closely mimic solid tumors than two-dimensional(2D) cancer cells in terms of the spatial structure, extracellular matrix-cell interaction, and gene expression pattern. However, no study has been reported on the differences in lipid metabolism and distribution among 2D cancer cells, MCTS, and solid tumors. Here, we used Hep G2 liver cancer cell lines to establish these three cancer models. The variations of lipid profiles and spatial distribution among them were explored by using mass spectrometry-based lipidomics and matrix-assisted laser desorption/ionization mass spectrometry imaging(MSI). The results revealed that MCTS, relative to 2D cells, had more shared lipid species with solid tumors. Furthermore,MCTS contained more comparable characteristics than 2D cells to solid tumors with respect to the relative abundance of most lipid classes and mass spectra patterns. MSI data showed that 46 of 71 lipids had similar spatial distribution between solid tumors and MCTS, while lipids in 2D cells had no specific spatial distribution. Interestingly, most of detected lipid species in sphingolipids and glycerolipids preferred locating in the necrotic region to the proliferative region of solid tumors and MCTS. Taken together, our study provides the evidence of lipid metabolism and distribution demonstrating that MCTS are a more suitable in vitro model to mimic solid tumors, which may offer insights into tumor metabolism and microenvironment.

Effect of bacterial intra-species community interactions on the production and activity of volatile organic compounds

Microorganisms experience intra-and inter-species interactions in the soil,and how these interactions affect the production of microbial volatile organic compounds(VOCs)is still not well-known.Here we evaluated the production and activity of microbial VOCs as driven by bacterial intra-species community interactions.We set up bacterial communities of increasing biodiversity out of 1–4 strains each of the Gram-positive Bacillus and Gram-negative Pseudomonas genera.We evaluated the ability of each community to provide two VOCmediated services,pathogen suppression and plant-growth promotion and then correlated these services to the production of VOCs by each community.The results showed that an increase in community richness from 1 to 4 strains of both genera increased VOC-mediated pathogen suppression and plant-growth promotion on agar medium and in the soil,which was positively correlated with the production of pathogen suppressing and plant growth-promoting VOCs.Pseudomonas strains maintained while Bacillus strains reduced community productivity with an increase in community richness and produced eight novel VOCs compared with the monocultures.These results revealed that intra-species interactions may vary between Gram-negative and Gram-positive species but improved VOC-mediated functioning with respect to pathogen suppression and plant-growth promotion by affecting the amount and diversity of produced VOCs potentially affecting plant disease outcomes.

Complete Parasitic Capacitance Model of Photovoltaic Panel Considering the Rain Water

Common mode current suppression is important to grid-connected photovoltaic(PV)systems and depends strongly on the value of the parasitic capacitance between the PV panel and the ground.Some parasitic capacitance models have been proposed to evaluate the magnitude of the effective parasitic capacitance.However,the proposed model is only for the PV panels under dry and clean environmental conditions.The dependence of rain water on the capacitance is simply described rather than analyzing in detail.Furthermore,the effects of water are addressed quite differently in papers.Thus,this paper gives complete parasitic capacitance model of the PV panel considering the rain water.The effect of the water on the capacitance is systematically investigated through 3D finite element(FE)electromagnetic(EM)simulations and experiments.Accordingly,it is clarified how the water affects the parasitic capacitance and methods of minimization of the capacitance are proposed.

In-situ Health Monitoring of IGBT Modules of an On-line Medium-voltage Inverter System Using Industrial Internet of Things

Requirements of the Internet of things for the network includes the ability to monitor the equipment and devices.Nowadays,the reliability of a power electronics converter has raised concerns of both academia and industry.In particular,power semiconductor devices are continuously exposed to excessive stress while being designed with high power handling capability and are considered as the most fragile component in power converters suffering from a high failure rate.Aiming to find an effective monitoring method which is also helpful for the Internet of Things and improve the reliability of a three-level neutral-point-clamped power inverter,an in-situ health monitoring method is proposed by harnessing the inverter operational characteristics and degradation sensitive electrical parameters to address the IGBT wire bonding faults.The zero voltage state provides an inherent redundant feature that allows for a power switch to be diagnosed during its normal operation in a neutralpoint-clamped power inverter.The proposed prognostic approach obtains both the wire bonding failure features and junction temperature from the terminals of an IGBT module,which is regarded as non-invasive on-line health monitoring.The system performance can be affected by the designated testing point and testing window,which is discussed and experimentally validated.The proposed technique allows unhealthy wire bonding in IGBT modules online monitoring during the operational period of the inverter.And the proposed in-situ health monitoring of IGBT modules can be used for the industrial Internet of things.