Showing papers by "Yue Lin published in 2022"

High-precision and linear weight updates by subnanosecond pulses in ferroelectric tunnel junction for neuro-inspired computing

Abstract: The rapid development of neuro-inspired computing demands synaptic devices with ultrafast speed, low power consumption, and multiple non-volatile states, among other features. Here, a high-performance synaptic device is designed and established based on a Ag/PbZr0.52Ti0.48O3 (PZT, (111)-oriented)/Nb:SrTiO3 ferroelectric tunnel junction (FTJ). The advantages of (111)-oriented PZT (~1.2 nm) include its multiple ferroelectric switching dynamics, ultrafine ferroelectric domains, and small coercive voltage. The FTJ shows high-precision (256 states, 8 bits), reproducible (cycle-to-cycle variation, ~2.06%), linear (nonlinearity <1) and symmetric weight updates, with a good endurance of >109 cycles and an ultralow write energy consumption. In particular, manipulations among 150 states are realized under subnanosecond (~630 ps) pulse voltages ≤5 V, and the fastest resistance switching at 300 ps for the FTJs is achieved by voltages <13 V. Based on the experimental performance, the convolutional neural network simulation achieves a high online learning accuracy of ~94.7% for recognizing fashion product images, close to the calculated result of ~95.6% by floating-point-based convolutional neural network software. Interestingly, the FTJ-based neural network is very robust to input image noise, showing potential for practical applications. This work represents an important improvement in FTJs towards building neuro-inspired computing systems.

High-precision and linear weight updates by subnanosecond pulses in ferroelectric tunnel junction for neuro-inspired computing

Abstract: The rapid development of neuro-inspired computing demands synaptic devices with ultrafast speed, low power consumption, and multiple non-volatile states, among other features. Here, a high-performance synaptic device is designed and established based on a Ag/PbZr0.52Ti0.48O3 (PZT, (111)-oriented)/Nb:SrTiO3 ferroelectric tunnel junction (FTJ). The advantages of (111)-oriented PZT (~1.2 nm) include its multiple ferroelectric switching dynamics, ultrafine ferroelectric domains, and small coercive voltage. The FTJ shows high-precision (256 states, 8 bits), reproducible (cycle-to-cycle variation, ~2.06%), linear (nonlinearity <1) and symmetric weight updates, with a good endurance of >109 cycles and an ultralow write energy consumption. In particular, manipulations among 150 states are realized under subnanosecond (~630 ps) pulse voltages ≤5 V, and the fastest resistance switching at 300 ps for the FTJs is achieved by voltages <13 V. Based on the experimental performance, the convolutional neural network simulation achieves a high online learning accuracy of ~94.7% for recognizing fashion product images, close to the calculated result of ~95.6% by floating-point-based convolutional neural network software. Interestingly, the FTJ-based neural network is very robust to input image noise, showing potential for practical applications. This work represents an important improvement in FTJs towards building neuro-inspired computing systems.

Defective Fe Metal–Organic Frameworks Enhance Metabolic Profiling for High‐Accuracy Diagnosis of Human Cancers

Abstract: Cancers heavily threaten human life; therefore, a high‐accuracy diagnosis is vital to protect human beings from the suffering of cancers. While biopsies and imaging methods are widely used as current technologies for cancer diagnosis, a new detection platform by metabolic analysis is expected due to the significant advantages of fast, simple, and cost‐effectiveness with high body tolerance. However, the signal of molecule biomarkers is too weak to acquire high‐accuracy diagnosis. Herein, precisely engineered metal–organic frameworks for laser desorption/ionization mass spectrometry, allowing favorable charge transfer within the molecule–substrate interface and mitigated thermal dissipation by adjusting the phonon scattering with metal nodes, are developed. Consequently, a surprising signal enhancement of ≈10 000‐fold is achieved, resulting in diagnosis of three major cancers (liver/lung/kidney cancer) with area‐under‐the‐curve of 0.908–0.964 and accuracy of 83.2%–90.6%, which promises a universal detection tool for large‐scale clinical diagnosis of human cancers.

Dehydrogenation of Ammonia Borane by Platinum--Nickel Dimers: Regulation of the Heteroatom Interspace Boosts Bifunctional Synergetic Catalysis.

Abstract: Regulation of the atom-atom interspaces of dual-atom catalysts is essential to optimize the dual-atom synergy to achieve high activity but remains challenging. Herein, we report an effective strategy to regulate the Pt 1 -Ni 1 interspace to achieve Pt 1 Ni 1 dimers and Pt 1 +Ni 1 heteronuclear dual-single-atom catalysts (HDSACs) by tailoring steric hindrance between metal precursors during synthesis. Spectroscopic characterization reveals obvious electron transfers in Pt 1 Ni 1 oxo dimers but not in Pt 1 +Ni 1 HDSAC. In the hydrolysis of ammonia borane (AB), the H 2 formation rates show an inverse proportion to the Pt 1 -Ni 1 interspace. The rate of Pt 1 Ni 1 dimers is ~13 and 2 times higher than those of Pt 1 and Pt 1 +Ni 1 HDSAC, manifesting the interspace-dependent synergy. Theoretical calculations reveal that the bridging OH group in Pt 1 Ni 1 dimers promotes water dissociation, while Pt 1 facilitates the cleavage of B-H bonds in AB, which boosts a bifunctional synergy to accelerate H 2 production cooperatively.

A Redox Couple Strategy Enables Long‐Cycling Li‐ and Mn‐Rich Layered Oxide Cathodes by Suppressing Oxygen Release

Abstract: Li‐ and Mn‐rich layered oxides (LMROs) are considered the most promising cathode candidates for next‐generation high‐energy lithium‐ion batteries. The poor cycling stability and fast voltage fading resulting from oxygen release during charging, however, severely hinders their practical application. Herein, a strategy of introducing an additional redox couple is proposed to eliminate the persistent problem of oxygen release. As a proof of concept, the cycling stability of Li1.2Ni0.13Co0.13Mn0.54O2, which is a typical LMRO cathode, is substantially enhanced with the help of the S2−/SO32− redox couple, and the capacity shows no decay with a retention of 100% after 700 cycles at 1C, far superior to the bare counterpart (61.7%). The surface peroxide ions (O22−) are readily chemically reduced back to immobile O2− by S2− during charging, accompanied by the formation of SO32−, which plays a critical role in stabilizing the oxygen lattice and eventually inhibiting the release of oxygen. More importantly, the S2− ions are regenerated during the following discharging process and participate in the chemical redox reaction again. The findings shed light on a potential direction to tackle the poor cycling stability of high‐energy anion‐redox cathode materials for rechargeable metal‐ion batteries.

Metformin suppresses pro-inflammatory cytokines in vitreous of diabetes patients and human retinal vascular endothelium

Abstract: Metformin is a traditional anti-hyperglycemic medication that has recently been shown to benefit vascular complications of diabetes via an anti-inflammatory mechanism other than glycemic control. This study aims to test the hypothesis that metformin suppresses diabetic retinopathy (DR) associated intraocular inflammation. Human vitreous from control and proliferative diabetic retinopathy (PDR) patients with or without long-term metformin treatment (> 5 years) were collected for multiple inflammatory cytokines measurements with a cytokine array kit. The vast majority of the measurable cytokines in PDR vitreous has a lower level in metformin group than non-metformin group. Although the p values are not significant due to a relatively small sample size and large deviations, the 95% confidence interval (CI) for the mean difference between the two groups shows some difference in the true values should not be neglected. Using quantitative ELISA, soluble intercellular adhesion molecule -1 (ICAM-1) and monocyte chemoattractant protein -1 (MCP-1) presented with significantly lower concentrations in metformin group versus non-metformin group. Metformin group also has significantly less up-regulated cytokines and diminished positive correlations among the cytokines when compared to non-metformin group. Possible role of AMP-activated protein kinase (AMPK) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) in metformin’s anti-inflammatory effects were studied in human retinal vascular endothelial cells (hRVECs) cultured in normal glucose (NG) and high glucose (HG) conditions. Metformin inhibited HG-induced ICAM-1, IL-8, and MCP-1 via AMPK activation, whereas pharmacological AMPK inhibition had no effect on its inhibition of NF-κB p65, sICAM-1, and tumor necrosis factor-α (TNF-α). Metformin-induced suppression of the inflammatory cytokines could also be mediated through its direct inhibition of NF-κB, independent of AMPK pathway. This is a proof-of-concept study that found metformin treatment was associated with reduced inflammatory responses in vitreous of diabetes patients and retinal vascular endothelial cells, supporting the rationale for using metformin to treat DR at an early stage.

High-Energy and Long-Cycling All-Solid-State Lithium-Ion Batteries with Li- and Mn-Rich Layered Oxide Cathodes and Sulfide Electrolytes

Abstract: All-solid-state lithium-ion batteries (ASSLIBs) are considered the most promising option for next-generation high-energy and safe batteries. Herein, a practical all-solid-state battery, with a Li- and Mn-rich layered oxide (LMRO) as the cathode and Li6PS5Cl as the electrolyte, is demonstrated for the first time. The battery delivers the most exceptional performance by far in terms of ultrahigh capacity of 244.5 mA h g–1 and unprecedented cycling stability with an 83% capacity retention after 1000 cycles. We discover that the Li6PS5Cl can be reversibly oxidized and reduced within the voltage range 2.0–4.8 V, which is beneficial to the ionic conduction during long-term cycling of ASSLIBs. Moreover, the electronic and ionic conductivities of LMROs are increased by 4 orders of magnitude via precisely tailoring the composition and structure. In addition, the typical dissolution of transition metal, oxygen release, and phase transformation of LMROs in liquid batteries are substantially eliminated in ASSLIBs.

Planar defect–free pure red perovskite light-emitting diodes via metastable phase crystallization

Abstract: Solution-processable all-inorganic CsPbI3−xBrx perovskite holds great potential for pure red light-emitting diodes. However, the widely existing defects in this mixed halide perovskite markedly limit the efficiency and stability of present light-emitting diode devices. We here identify that intragrain Ruddlesden-Popper planar defects are primary forms of such defects in the CsPbI3−xBrx thin film owing to the lattice strain caused by inhomogeneous halogen ion distribution. To eliminate these defects, we develop a stepwise metastable phase crystallization strategy to minimize the CsPbI3−xBrx perovskite lattice strain, which brings planar defect–free CsPbI3−xBrx thin film with improved radiative recombination, narrowed emission band, and enhanced spectral stability. Using these high-quality thin films, we fabricate spectrally stable pure red perovskite light-emitting diodes, showing 17.8% external quantum efficiency and 9000 candela meter−2 brightness with color coordinates required by Rec. 2020.

Phase-Controlled Synthesis of Nickel-Iron Nitride Nanocrystals Armored with Amorphous N-Doped Carbon Nanoparticles Nanocubes for Enhanced Overall Water Splitting.

Abstract: Transition metal nitrides (TMNs) nanostructures possess distinctive electronic, optical, and catalytic properties, showing great promise to apply in clean energy, optoelectronics, and catalysis fields. Nonetheless, phase-regulation of NiFe-bimetallic nitrides nanocrystals or nanohybrid architectures confronts challenges and their electrocatalytic overall water splitting (OWS) performances are underexplored. Herein, novel pure-phase Ni2+ x Fe2- x N nanocrystals armored with amorphous N-doped carbon (NC) nanoparticles nanocubes (NPNCs) are obtained by controllable nitridation of NiFe-Prussian-blue analogues derived oxides/NC NPNCs under Ar/NH3 atmosphere. Such Ni2+ x Fe2- x N/NC NPNCs possess mesoporous structures and show enhanced electrocatalytic activity in 1 m KOH electrolyte with the overpotential of 101 and 270 mV to attain 10 and 50 mA cm-2 current toward hydrogen and oxygen evolution reactions, outperforming their counterparts (mixed-phase NiFe2 O4 /Ni3 FeN/NC and NiFe oxides/NC NPNCs). Remarkably, utilizing them as bifunctional catalysts, the assembled Ni2+ x Fe2- x N/NC||Ni2+ x Fe2- x N/NC electrolyzer only needs 1.51 V cell voltage for driving OWS to approach 10 mA cm-2 water-splitting current, exceeding their counterparts and the-state-of-art reported bifunctional catalysts-based devices, and Pt/C||IrO2 couples. Additionally, the Ni2+ x Fe2- x N/NC||Ni2+ x Fe2- x N/NC manifests excellent durability for OWS. The findings presented here may spur the development of advanced TMNs nanostructures by combining phase, structure engineering, and hybridization strategies and stimulate their applications toward OWS or other clean energy fields.

Operando Direct Observation of Stable Water-Oxidation Intermediates on Ca2-xIrO4 Nanocrystals for Efficient Acidic Oxygen Evolution.

Abstract: We report Ca2-xIrO4 nanocrystals exhibit record stability of 300 h continuous operation and high iridium mass activity (248 A gIr-1 at 1.5 VRHE) that is about 62 times that of benchmark IrO2. Lattice-resolution images and surface-sensitive spectroscopies demonstrate the Ir-rich surface layer (evolved from one-dimensional connected edge-sharing [IrO6] octahedrons) with high relative content of Ir5+ sites, which is responsible for the high activity and long-term stability. Combining operando infrared spectroscopy with X-ray absorption spectroscopy, we report the first direct observation of key intermediates absorbing at 946 cm-1 (Ir6+═O site) and absorbing at 870 cm-1 (Ir6+OO- site) on iridium-based oxides electrocatalysts, and further discover the Ir6+═O and Ir6+OO- intermediates are stable even just from 1.3 VRHE. Density functional theory calculations indicate the catalytic activity of Ca2IrO4 is enhanced remarkably after surface Ca leaching, and suggest IrOO- and Ir═O intermediates can be stabilized on positive charged active sites of Ir-rich surface layer.

Latticed-Confined Conversion Chemistry of Battery Electrode.

Abstract: The electrochemical conversion reaction, usually featured by multiple redox processes and high specific capacity, holds great promise in developing high-energy rechargeable battery technologies. However, the complete structural change accompanied by spontaneous atomic migration and volume variation during the charge/discharge cycle leads to electrode disintegration and performance degradation, therefore severely restricting the application of conventional conversion-type electrodes. Herein, latticed-confined conversion chemistry is proposed, where the "intercalation-like" redox behavior is realized on the electrode with a "conversion-like" high capacity. By delicately formulating the high-entropy compounds, the pristine crystal structure can be preserved by the inert lattice framework, thus enabling an ultra-high initial Coulombic efficiency of 92.5% and a long cycling lifespan over a thousand cycles after the quasistatic charge-discharge cycle. This lattice-confined conversion chemistry unfolds a ubiquitous insight into the localized redox reaction and sheds light on developing high-performance electrodes toward next-generation high-energy rechargeable batteries.

Self‐Supported Gold‐Silk‐Chrysanthemum‐Like Superstructures Arrays Derived from Mn‐doped CoPS Nanowires with Superhydrophilic and Superaerophobic Surface for Enhanced Oxygen Evolution

Abstract: Metal phosphosulfides (layered MPS3 or pyrite‐type MPS) nanostructures have emerged as promising active materials for optoelectronics, magnetism, energy storage, and catalysis. Despite great progress that has been achieved, controllable synthesis of cationic‐doped CoPS nanostructures or related superstructures arrays remains challenging, and their electrocatalytic applications toward oxygen evolution reaction (OER) are not explored. Herein, the self‐supported Mn‐doped CoPS nanowire‐based gold‐silk‐chrysanthemum‐like superstructures arrays on carbon cloth (CC) with variable Mn‐content (Mn‐CoPS‐x%/CC) are fabricated by thermal conversion of MnCo‐layered‐double‐hydroxides‐x%/CC precursors under PxSy vapor/Ar atmosphere. Compared with pure CoPS/CC, all the Mn‐CoPS‐x%/CC show greatly enhanced electrocatalytic OER activity. Due to the suited Mn‐doping content and unique microstructure‐induced superhydrophilic and superaerophobic surface that can optimize electronic structure, offer more available active sites, and foster desorption of O2 product, the Mn‐CoPS‐5%/CC manifests the best OER activity with a low overpotential (270 mV) to reach 20 mA cm−2 current density and high turnover frequency (0.13 s−1), outperforming its counterparts, IrO2/CC and most of recently reported OER catalysts. Moreover, such Mn‐CoPS‐5%/CC exhibits good catalytic stability. This work offers an efficient avenue for optimizing MPS nanostructures toward OER by combining doping and structure engineering strategies, and may promote their applications in water‐splitting or other clean energy options.

In situ Observation of Structural Evolution and Phase Engineering of Amorphous Materials during Crystal Nucleation

Abstract: The nucleation pathway determines the structures and thus properties of formed nanomaterials, which is governed by the free energy of the intermediate phase during nucleation. The amorphous structure, as one of the intermediate phases during nucleation, plays an important role in modulating the nucleation pathway. However, the process and mechanism of crystal nucleation from amorphous structures still need to be fully investigated. Here, in situ aberration‐corrected high‐angle annular dark‐field scanning transmission electron microscopy (HAADF‐STEM) is employed to conduct real‐time imaging of the nucleation of ultrathin amorphous nanosheets (NSs). The results indicate that their nucleation contains three distinct stages, i.e., aggregation of atoms, crystallization to form lattice‐expanded nanocrystals, and relaxation of the lattice‐expanded nanocrystals to form final nanocrystals. In particular, the crystallization processes of various amorphous materials are investigated systematically to form corresponding nanocrystals with unconventional crystalline phases, including face‐centered‐cubic (fcc) Ru, hexagonal‐close‐packed (hcp) Rh, and a new intermetallic IrCo alloy. In situ electron energy‐loss spectroscopy (EELS) analysis unveils that the doped carbon in the original amorphous NSs can migrate to the surface during the nucleation process, stabilizing the obtained unconventional crystal phases transformed from the amorphous structures, which is also proven by density functional theory (DFT) calculations.

Hydrogen Peroxide Assisted Electrooxidation of Benzene to Phenol over Bifunctional Ni–(O–C2)4 Sites

Abstract: Direct electrocatalytic oxidation of benzene has been regarded as a promising approach for achieving high‐value phenol product, but remaining a huge challenge. Here an oxygen‐coordinated nickel single‐atom catalyst (Ni–O–C) is reported with bifunctional electrocatalytic activities toward the two‐electron oxygen reduction reaction (2e− ORR) to H2O2 and H2O2‐assisted benzene oxidation to phenol. The Ni–(O–C2)4 sites in Ni–O–C ar proven to be the catalytic active centers for bifunctional 2e− ORR and H2O2‐assisted benzene oxidation processes. As a result, Ni–O–C can afford a benzene conversion as high as 96.4 ± 3.6% with a phenol selectivity of 100% and a Faradaic efficiency (FE) of 80.2 ± 3.2% with the help of H2O2 in 0.1 m KOH electrolyte at 1.5 V (vs RHE). A proof of concept experiment with Ni–O–C concurrently as cathode and anode in a single electrochemical cell demonstrates a benzene conversion of 33.4 ± 2.2% with a phenol selectivity of 100% and a FE of 44.8 ± 3.0% at 10 mA cm−2.

Temporal Prediction Model-Based Fast Inter CU Partition for Versatile Video Coding

Abstract: Versatile video coding (VVC) adopts an advanced quad-tree plus multi-type tree (QTMT) coding structure to obtain higher compression efficiency, but it comes at the cost of a considerable increase in coding complexity. To effectively reduce the coding complexity of the QTMT-based coding unit (CU) partition, we propose a fast inter CU partition method based on a temporal prediction model, which includes early termination QTMT partition and early skipping multi-type tree (MT) partition. Firstly, according to the position of the current CU, we extract the optimal CU partition information of the position corresponding to the previously coded frames. We then establish a temporal prediction model based on temporal CU partition information to predict the current CU partition. Finally, to reduce the cumulative of errors of the temporal prediction model, we further extract the motion vector difference (MVD) of the CU to determine whether the QTMT partition can be terminated early. The experimental results show that the proposed method can reduce the inter coding complexity of VVC by 23.19% on average, while the Bjontegaard delta bit rate (BDBR) is only increased by 0.97% on average under the Random Access (RA) configuration.

A Smart Reference Picture Resampling Approach for VVC

Abstract: Resampling-based coding, i.e. down-sampling before encoding and up-sampling after decoding, has been recognized to be an effective tool for compressing high-resolution videos at low bitrates. The newest video coding standard, Versatile Video Coding (VVC), supports resampling-based coding via a mechanism named Reference Picture Resampling (RPR), where the spatial resolution can be changed without inserting an intra frame. Intuitively, it is not wise to utilize a single resolution throughout the whole video, because frames with different contents may prefer different coding resolutions. In this paper, we propose a smart reference picture resampling approach, namely smart-RPR, where the coding-resolution of a frame is determined based on the property of the frame without multiple-pass encoding. Specifically, we first down- and up-sample a frame without considering compression and compare the up-sampled frame with the original frame to obtain the resampling distortion, which is then compared with a threshold to decide whether to code the frame in a resampling way. Then, we build up an exponential model to approximate the optimal threshold. In addition, we also study how to derive the coding parameters of the down-sampled frame to achieve better performance. Simulation results on the VTM-12.0 show that the proposed method could achieve 2.72%, 5.29%, and 10.82% BD-rate reductions for Y, Cb, and Cr components, respectively, with lower encoding and decoding complexity.

Tunable early CU size decision for depth map intra coding in 3D-HEVC using unsupervised learning

Abstract: To further improve coding gain for depth map in 3D extension of High Efficiency Video Coding (3D-HEVC), many new coding techniques are introduced, which drastically increase the coding complexity. In this work, an early intra coding unit (CU) size decision scheme is proposed for 3D-HEVC intra depth map coding based on unsupervised learning approach. First, we treat the early CU size decision as a clustering problem. Then, three clustering models are developed for those CUs with the sizes of 64×64, 32×32 and 16×16 to early determine whether they be further split or not. Among them, the center of the clustering model is obtained by using intra learning method. Finally, in order to meet the user's specific application preference, the similarity distance is introduced into the early CU size decision. By adjusting the similarity distance, a tunable early CU size decision is achieved to obtain different levels of coding complexity reduction. Experimental results show that the proposed scheme achieves encoding time reduction ranging from 54.0% to 68.4% on average for depth map intra coding, while the Bjontegaard delta bit rate (BDBR) of synthesized views only increased by 0.01% to 0.73%, it outperforms the state-of-the-art works in term of coding complexity reduction and BDBR increase.

Rice Production in Future: More Challenges Come from Frequent Extreme Weathers

Abstract: Modern Concepts & Developments in Agronomy Rice Production in Future: More Challenges Come from Frequent Extreme Weathers Jiajun Yan#, Meizhen Yang#, Kui Wu, Lu Peng, Jintian Chen and Yu Ling* College of Coastal Agricultural Sciences, Guangdong Ocean University, Zhanjiang, Chin *Corresponding author: Yu Ling, College of Coastal Agricultural Sciences, Guangdong Ocean University, Zhanjiang, China Submission: May 11, 2022;Published: May 20, 20222 DOI: 10.31031/MCDA.2022.10.000749 ISSN 2637-7659Volume10 Issue 5

Harvesting the Gas Molecules by Bioinspired Design of 1D/2D Hybrids Toward Sensitive Acetone Detecting

Abstract: Single‐atom catalysts (SACs) are highly attractive in many surface‐dependent reactions due to their extraordinary reactivity and maximum atomic efficiency. However, in a practical catalytic system, guiding and transferring the reactant molecules to target single‐atom sites are crucial processes for achieving high‐efficient reactions. Herein, gas‐microchannels on TiO2 nanorod‐supported Pt single‐atom catalyst by in situ growing derivative TiO2 nanosheets are constructed. Those perpendicular‐grown TiO2 nanosheets can guide gas molecules to the reactive single Pt sites and thus realize an intact system of guidance‐transfer‐reaction. Experimentally, the local coordination and electronic states of Pt species decrease with the growth of nanosheets, which could significantly strengthen the adsorption and activation of oxygen molecules toward the acetone sensing. The final Pt1/TiO2 catalysts exhibit a high sensing response (13.6–50 ppm) to acetone gas, which are approximately three times higher than that of catalysts without scaly shell (4.8–50 ppm).