Pre-oxidized and composite strategy greatly boosts performance of polyacrylonitrile/LLZO nanofibers for lithium-metal batteries.

The active cyano-group in polyacrylonitrile has severe passivation of lithium anode under larger current density, which restricts the wide application of polyacrylonitrile(PAN) in lithium metal batteries. Herein, in order to address the excessive passivation of lithium metal by PAN, inspired by the pre-oxidation of carbon fibers, PAN was pre-oxidized at 230 °C, which transformed part of the cyano group into a more chemically stable cyclized structure. The electrochemical and mechanical properties of the composite solid electrolyte were effectively improved by introducing the fast ionic conductor Li6.25La3Zr2Al0.25O12 into PAN by electrospinning. The oxidized PAN-based composite solid electrolyte presents high ionic conductivity (3.05 × 10-3 S·cm-1) and high lithium transference number of 0.79 at 25 °C, further contributing to a high electrochemical window (5.3 V). The solid-state batteries assembled by Li||10 wt%-LLZAO@230-oxy-PAN||NCM523 behave superb electrochemical performance, delivering a high initial discharge capacity of 157 mAh g-1 at 0.2 C. After 100 cycles, the capacity retention was 93.3 %, indicating the electrolyte displays great electrochemical stability. This work provides new insights into the structural design of polymer-based high-voltage batteries.

An initiator-free and solvent-free in-situ self-catalyzed crosslinked polymer electrolyte for all-solid-state lithium-metal batteries.

Linear polymer (e.g. polyethylene oxide, PEO) based electrolytes have been widely studied due to their flexibility and relatively good contact against electrodes. However, the linear polymers are prone to crystallization at room temperature and melting at moderate temperature, restricting their application in lithium metal batteries. To address these problems, a self-catalyzed crosslinked polymer electrolyte (CPE) was designed and prepared by the reaction of poly (ethylene glycol diglycidyl ether) (PEGDGE) and polyoxypropylenediamine (PPO) with only the bistrifluoromethanesulfonimide lithium salt (LiTFSI) added and with no any initiators. LiTFSI catalyzed the reaction by reducing the activation energy to form a crosslinked network structure, which was identified by calculation, NMR and FTIR. The as-prepared CPE has high resilience and a low glass transition temperature (Tg = -60 °C). Meanwhile, the solvent-free in-situ polymerization technique has been adopted in the assembly of the CPE with electrodes to decrease the interfacial impedance greatly and improve the ionic conductivity to 2.05 × 10-5 S cm-1 and 2.55 × 10-4 S cm-1 at room temperature and 75 °C, respectively. As a result, the in-situ LiFeO4/CPE/Li battery exhibits outstanding thermal and electrochemical stability at 75 °C. Our work has proposed an initiator-free and solvent-free in-situ self-catalyzed strategy of preparing high performance crosslinked solid polymer electrolytes.

A high performance composite separator with robust environmental stability for dendrite-free lithium metal batteries.

The garnet ceramic Li6.4La3Zr1.4Ta0.6O12 (LLZTO) modified separators have been proposed to overcome the poor thermal stability and wettability of commercial polyolefin separators. However, the side reaction of LLZTO in the air leads to deterioration of environmental stability of composite separators (PP-LLZTO), which will limit the electrochemical performance of batteries. Herein, the LLZTO with the polydopamine (PDA) coating (LLZTO@PDA) was prepared by solution oxidation, and then applied it to a commercial polyolefin separator to achieve a composite separator (PP-LLZTO@PDA). LLZTO@PDA is stable in the air, and no Li2CO3 can be observed on the surface even after 90 days in the air. Besides, LLZTO@PDA coating endows the PP-LLZTO@PDA separator with the tensile strength (up to 103 MPa), good wettability (contact angle 0°) and high ionic conductivity (0.93 mS cm-1). Consequently, the Li/PP-LLZTO@PDA/Li symmetric cell cycles stably for 600 h without significant dendrites generation, and the assembled Li//LFP cells with PP-LLZTO@PDA-D30 separators deliver a high capacity retention of 91.8% after 200 cycles at 0.1C. This research provides a practical strategy for constructing composite separators with excellent environmental stability and high electrochemical properties.

Application and Research Progress of Covalent Organic Frameworks for Solid-State Electrolytes in Lithium Metal Batteries.

Covalent organic frameworks (COFs) are a class of crystalline porous organic polymers with periodic networks that are constructed from small molecular units via covalent bonds, which have low densities, high porosity, large specific surface area, and ease of functionalization. The one-dimension nanochannels in COFs offer an effective means of transporting lithium ions while maintaining a stable structure over a wide range of temperatures. As a new category of ionic conductors, COFs exhibit unparalleled application potential in solid-state electrolytes. Here, we provide a comprehensive summary of recent applications and research progress for COFs in solid-state electrolytes of lithium metal batteries and discuss the possible development directions in the future. This review is expected to provide theoretical guidance for the design of high-performance solid-state electrolytes.

Novel In Situ Growth of ZIF-8 in Porous Epoxy Matrix for Mechanically Robust Composite Electrolyte of High-Performance, Long-Life Lithium Metal Batteries.

Polymer electrolytes (PEs) with high flexibility, low cost, and excellent interface compatibility have been considered as an ideal substitute for traditional liquid electrolytes for high safety lithium metal batteries (LMBs). Nevertheless, the mechanical strength of PEs is generally poor to prevent the growth of lithium dendrites during the charge/discharge process, which seriously restricts their wide practical applications. Herein, a mechanical robust ZIF-8/epoxy composite electrolyte with unique pore structure was prepared, which effectively inhibited the growth of lithium dendrites. Meanwhile, the in situ growth of ZIF-8 in porous epoxy matrix can promote the uniform flux and fast transport of lithium ions. Ultimately, the optimal electrolyte shows high ionic conductivity (2.2 × 10-3 S cm-1), wide electrochemical window (5 V), and a large Li+ transference number (0.70) at room temperature. The Li||NCM811 cell using the optimal electrolyte exhibits high capacity and excellent cycling performance (83.2% capacity retention with 172.1 mA h g-1 capacity retained after 200 cycles at 0.2 C). These results indicate that the ZIF-8/epoxy composite electrolyte is of great promise for the application in LMBs.

Gualou Xiebai Decoction ameliorates increased Caco-2 monolayer permeability induced by bile acids via tight junction regulation, oxidative stress suppression and apoptosis reduction.

Gualou Xiebai Decoction (GXD), a classic prescription, is widely used to dealing with inflammatory diseases in China for thousands of years. Abnormal metabolic state of bile acids (BAs) is confirmed to cause intestinal epithelial barrier dysfunction. In preliminary work, we observed that GXD could decrease intestinal permeability in hyperlipidemia mice. The present study aimed to explore the protective effect of GXD on intestinal mucosa in vitro. Caco-2 cell monolayer permeability among different groups was determined by measuring the concentrations of FITC-dextran in the lower compartments and transepithelial electrical resistance (TEER). Meanwhile, mRNA and protein expressions of tight junctions (TJs) were investigated. Generation of intracellular reactive oxygen species (ROS) and the ratio of cell apoptosis induced by BAs were assessed by fluorescence probe and flow cytometry. GXD was shown to keep the cell monolayer in low permeable status, increase TEER and mRNA and protein expressions of occludin (Ocln) and zonula occluden 2 (ZO2) remarkably in cells challenged with cholic acid (CA), deoxycholic acid (DCA) and glycocholic acid (GCA). However, no significant effects were uncovered against the pathological effects of taurocholic acid (TCA). Meanwhile, generation of ROS and increased levels of apoptotic cells caused by CA, DCA and GCA were dramatically decreased by GXD, which were not observed on TCA. GXD could significantly attenuate intestinal barrier dysfunction induced by BAs via TJs regulation, oxidative stress suppression and cell apoptosis decrease, but such effects and behind mechanisms differed among different kinds of BAs.

Ketogenic diet attenuates aging-associated myocardial remodeling and dysfunction in mice.

Cardiac aging is manifested as unfavorable geometric and functional alterations in heart. The current work was to test whether a ketogenic diet (KD) impacted aging-associated myocardial remodeling and dysfunction in mice and investigate the underlying mechanism. The young and aged male mice were fed with KD or standard chow for four months. Echocardiography results revealed that KD decreased left ventricular end systolic diameter (LVESD) and increased fractional shortening in aged mice. With KD feeding, aged mice exhibited reduced cardiomyocyte cross-sectional area, fibrosis, and mRNA expression of atrial natriuretic peptide (ANP), Col1A1 and alpha smooth muscle actin (α-SMA) in myocardium. KD enhanced activities of superoxide dismutase 2 (SOD2), glutathione peroxidase (GPx) and catalase, and reduced the levels of malondialdehyde (MDA) and 3-nitrotyrosine (3-NT) in myocardium of aged mice. KD led to a downregulation of expression of C/EBP homologous protein (CHOP), glucose regulated protein 78 (GRP78), cleaved activated transcription factor 6 (ATF6), and spliced X box-binding protein 1 (XBP-1 s) in myocardium of aged mice. KD in aged mice reduced mitochondrial reactive oxygen species (ROS) formation, enhanced mitochondrial ATP production and mitochondrial membrane potential (MMP), and preserved activity of complex III and electron-coupling capacities between complexes I and III and between complexes II and III in myocardium. Importantly, KD in aged mice promoted autophagic flux, evidenced by reduced protein expression of p62 and enhanced protein expression of lysosome-associated membrane protein-2 (Lamp2) in myocardium. In conclusion, long-time KD intake delayed cardiac aging in male mice, possibly through abating oxidative stress, improving mitochondrial function, and promoting autophagic flux.

Effect of resin composition on performance of polymer-infiltrated feldspar-network composites for dental restoration.

This study intends to obtain a kind of polymer-infiltrated ceramic-network (PICN) composite with improved performance for dental restoration. Porous ceramic network was prepared via compressing feldspar powders, followed by resin infiltration using Bis-GMA/TEGDMA or UDMA/TEGDMA mixtures to obtain PICN composites after thermocuring. The sintering parameters (temperature, duration) for the formation of feldspathic network with proper porosity were investigated. The ratios of resin mixtures were adjusted to optimize the infiltration. Comprehensive characterizations were conducted on the porosity and the shrinkage of preformed ceramic-networks, the viscosity of resin mixtures and their infiltration into the ceramic networks, as well as, flexural properties, Vickers hardness and wear resistance of the final PICN composites. It turned out that the PICN composite prepared from Bis-GMA/TEGDMA (6:4) achieved the best performance among all the samples, which is expected to be a suitable material for computer-aided design/computer-aided manufacturing (CAD/CAM) dental restorative applications.

Superresilient Hard Carbon Nanofabrics for Sodium-Ion Batteries.

Developing supermechanically resilient hard carbon materials that can quickly accommodate sodium ions is highly demanded in fabricating durable anodes for wearable sodium-ion batteries. Here, an interconnected spiral nanofibrous hard carbon fabric with both remarkable resiliency (e.g., recovery rate as high as 1200 mm s-1 ) and high Young's modulus is reported. The hard carbon nanofabrics are prepared by spinning and then carbonizing the reaction product of polyacrylonitrile and polar molecules (melamine). The resulting unique hard carbon possesses a highly disordered carbonaceous structure with enlarged interlayer spacing contributed from the strong electrostatic repulsion of dense pyrrolic nitrogen atoms. Its excellent resiliency remains after intercalation/deintercalation of sodium ions. The outstanding sodium-storage performance of the derived anode includes excellent gravimetric capacity, high-power capability, and long-term cyclic stability. More significantly, with a high loading mass, the hard carbon anode displays a high-power capacity (1.05 mAh cm-2 at 2 A g-1 ) and excellent cyclic stability. This study provides a unique strategy for the design and fabrication of new hard carbon materials for advanced wearable energy storage systems.

An Ultra-microporous Carbon Material Boosting Integrated Capacitance for Cellulose-Based Supercapacitors.

A breakthrough in advancing power density and stability of carbon-based supercapacitors is trapped by inefficient pore structures of electrode materials. Herein, an ultra-microporous carbon with ultrahigh integrated capacitance fabricated via one-step carbonization/activation of dense bacterial cellulose (BC) precursor followed by nitrogen/sulfur dual doping is reported. The microporous carbon possesses highly concentrated micropores (~ 2 nm) and a considerable amount of sub-micropores (< 1 nm). The unique porous structure provides high specific surface area (1554 m2 g-1) and packing density (1.18 g cm-3). The synergistic effects from the particular porous structure and optimal doping effectively enhance ion storage and ion/electron transport. As a result, the remarkable specific capacitances, including ultrahigh gravimetric and volumetric capacitances (430 F g-1 and 507 F cm-3 at 0.5 A g-1), and excellent cycling and rate stability even at a high current density of 10 A g-1 (327 F g-1 and 385 F cm-3) are realized. Via compositing the porous carbon and BC skeleton, a robust all-solid-state cellulose-based supercapacitor presents super high areal energy density (~ 0.77 mWh cm-2), volumetric energy density (~ 17.8 W L-1), and excellent cyclic stability.

Composite resin reinforced with fluorescent europium-doped hydroxyapatite nanowires for in-situ characterization.

OBJECTIVE: The object is to find an easy but efficient way to illustrate the in-situ dispersion of nano-scaled one-dimensional fillers in composite resins, and to correlate their dispersion status with the properties of composite resins. METHODS: Fluorescent europium-doped hydroxyapatite nanowires (HANW:Eu) were synthesized via the hydrothermal method. The HANW:Eu was mixed into Bis-GMA/TEGDMA (60/40, w/w) at different contents (1-5wt.%), and different processing methods (kneading, grinding, stirring) were tested to achieve good dispersion of HANW:Eu with the aid of fluorescent imaging system. Then, the mixtures of HANW:Eu and barium glass powder (BaGP) were kneaded into resin at a fixed content (70wt.%) while at different mixing ratios. In addition to the 3D fluorescent imaging, characterizations were carried out on mechanical properties, fractured surface, wear resistance and polymerization shrinkage, to correlate the composite properties of with the dispersion status of the incorporated HANW:Eu. RESULTS: By doping calcium with 5mol.% of europium, the obtained HANW:Eu displayed strong fluorescence, which made the illustration of its in-situ dispersion status within composites being possible. And this helped to judge that kneading was more efficient to homogeneously disperse HANW:Eu than grinding and stirring. However, it was illustrated vividly that HANW:Eu aggregated severely when it was co-incorporated with BaGP into composites at the total content of 70wt.%, which had not been previously revealed by other microscope observations. In comparison with composites containing 70wt.% of BaGP, improvements in the mechanical properties of resulting composites were identified for the cases containing 3wt.% of HANW and 67wt.% of BaGP, however, their wear volume loss and the polymerization shrinkage did not decrease as expected due to the HANW aggregations. SIGNIFICANCE: The fluorescent filler prepared in this study provides a feasible strategy to illustrate the in-situ dispersion status of inorganic fillers, which provides guidance for the processing of composite resins.

Exogenous IL-19 attenuates acute ischaemic injury and improves survival in male mice with myocardial infarction.

BACKGROUND AND PURPOSE: Myocardial infarction (MI) is one of the leading causes of death in China and often results in the development of heart failure. In this work, we tested the therapeutic role of Interleukin-19 (IL-19) in mice with MI and investigated the underlying molecular mechanism. EXPERIMENTAL APPROACH: Mice were subjected to MI by ligation of left anterior descending coronary artery (LAD) and treated with IL-19 (10ng g-1 ; i.p.). KEY RESULTS: Protein expression of IL-19 and its receptor in myocardium were upregulated 24 hrs post-MI in male mice. IL-19 treatment decreased infarct and apoptosis in myocardium, accompanied by enhanced haem oxygenase-1 (HO-1) activities and reduced malondialdehyde (MDA) formation. Pretreatment with IL-19 upregulated HO-1 expression in cultured neonatal mouse ventricular myocytes and attenuated oxygen-glucose deprivation (OGD)-induced injuries in vitro. Furthermore, IL-19 preserved cardiac function and improved survival of mice with MI. IL-19 reduced inflammatory infiltrates and suppressed formation of TNF-α, IL-1ß, and IL-6. More importantly, IL-19 inhibited polarization toward proinflammatory M1 macrophages and stimulated M2 macrophage polarization in myocardium of mice with MI. IL-19 enhanced protein levels of vascular endothelial growth factor (VEGF) and promoted angiogenesis in myocardium of mice with MI. In addition, IL-19 treatment increased DNA-binding of the transcription factor STAT3 in myocardium of mice with MI. CONCLUSIONS AND IMPLICATIONS: Treatment with exogenous IL-19 attenuated acute ischemic injury and improved survival of mice with MI. The mechanisms underlying these effects involved induction of HO-1, M2 macrophage polarization, angiogenesis, and STAT3 activation.

Self-Reconstructed Formation of a One-Dimensional Hierarchical Porous Nanostructure Assembled by Ultrathin TiO2 Nanobelts for Fast and Stable Lithium Storage.

Owing to their unique structural advantages, TiO2 hierarchical nanostructures assembled by low-dimensional (LD) building blocks have been extensively used in the energy-storage/-conversion field. However, it is still a big challenge to produce such advanced structures by current synthetic techniques because of the harsh conditions needed to generate primary LD subunits. Herein, a novel one-dimensional (1D) TiO2 hierarchical porous fibrous nanostructure constructed by TiO2 nanobelts is synthesized by combining a room-temperature aqueous solution growth mechanism with the electrospinning technology. The nanobelt-constructed 1D hierarchical nanoarchitecture is evolves directly from the amorphous TiO2/SiO2 composite fibers in alkaline solutions at ambient conditions without any catalyst and other reactant. Benefiting from the unique structural features such as 1D nanoscale building blocks, large surface area, and numerous interconnected pores, as well as mixed phase anatase-TiO2(B), the optimum 1D TiO2 hierarchical porous nanostructure shows a remarkable high-rate performance when tested as an anode material for lithium-ion batteries (107 mA h g-1 at ∼10 A g-1) and can be used in a hybrid lithium-ion supercapacitor with very stable lithium-storage performance (a capacity retention of ∼80% after 3000 cycles at 2 A g-1). The current work presents a scalable and cost-effective method for the synthesis of advanced TiO2 hierarchical materials for high-power and stable energy-storage/-conversion devices.

Treatment with D-ß-hydroxybutyrate protects heart from ischemia/reperfusion injury in mice.

The present study was designed to examine the protection of D-ß-hydroxybutyrate (BHB) against ischemia/reperfusion (I/R) injury in heart and investigate its underlying mechanism. Male adult mice were exposed to 30 min of ischemia and 24 h of reperfusion. Osmotic pumps were implanted subcutaneously 5 min before reperfusion for continuous delivery of the exogenous BHB (1.6 mmol/kg/24 h). Treatment with BHB reduced infarct size and levels of cardiac troponin I, creatine kinase and lactate dehydrogenase in serum, attenuated apoptosis in myocardium, and preserved cardiac function of I/R mice. Importantly, treatment of I/R mice with BHB promoted autophagic flux, evidenced by reduced the ratio of LC3-II/LC3-I and protein expression of p62 and enhanced protein expression of lysosome associated membrane protein-2 (Lamp2) in myocardium. Treatment of I/R mice with BHB reduced mitochondrial formation of reactive oxygen species, enhanced adenosine triphosphate production, attenuated mitochondrial swelling, and partly restored mitochondrial membrane potential in myocardium. Furthermore, treatment of I/R mice with BHB abated oxidative stress and attenuated endoplasmic reticulum stress in myocardium. Our results indicated that treatment with exogenous BHB protected heart from I/R injury in mice.

Bio-inspired spider-web-like membranes with a hierarchical structure for high performance lithium/sodium ion battery electrodes: the case of 3D freestanding and binder-free bismuth/CNF anodes.

High gravimetric energy density and volumetric energy density energy storage devices are highly desirable due to the rapid development of electric vehicles, and portable and wearable electronic equipment. Electrospinning is a promising technology for preparing freestanding electrodes with high gravimetric and volumetric energy density. However, the energy density of the traditional electrospun electrodes is restricted by the low mass loading of active materials (e.g. 20%-30 wt%). Herein, a biomimetic strategy inspired by the phenomenon of the sticky spider web is demonstrated as a high performance anode, which simultaneously improves the gravimetric and volumetric energy density. Freestanding carbon nanofiber (CNF) membranes containing over 50 wt% of bismuth were prepared by electrospinning and subsequent thermal treatment. Membranes consisting of CNF network structures bonded tightly with active Bi cluster materials, resulting in excellent mechanical protection and a fast charge transport path, which are difficult to achieve simultaneously. The composite membrane delivers high reversible capacity (483 mA h g-1 at 100 mA g-1 after 200 cycles) and high rate performance (242 mA h g-1 at 1 A g-1) as a lithium-ion battery anode. For use as a sodium ion battery, the composite membrane also shows a high reversible specific capacity of 346 mA h g-1 and outstanding cycling performance (186 mA h g-1 at 50 mA g-1 after 100 cycles). This work offers a simple, low cost and eco-friendly method for fabricating free-standing and binder-free composite electrodes with high loading used in LIBs and SIBs.

High-Performance Li-Ion Capacitor Based on an Activated Carbon Cathode and Well-Dispersed Ultrafine TiO2 Nanoparticles Embedded in Mesoporous Carbon Nanofibers Anode.

A novel Li-ion capacitor based on an activated carbon cathode and a well-dispersed ultrafine TiO2 nanoparticles embedded in mesoporous carbon nanofibers (TiO2@PCNFs) anode was reported. A series of TiO2@PCNFs anode materials were prepared via a scalable electrospinning method followed by carbonization and a postetching method. The size of TiO2 nanoparticles and the mesoporous structure of the TiO2@PCNFs were tuned by varying amounts of tetraethyl orthosilicate (TEOS) to increase the energy density and power density of the LIC significantly. Such a subtle designed LIC displayed a high energy density of 67.4 Wh kg-1 at a power density of 75 W kg-1. Meanwhile, even when the power density was increased to 5 kW kg-1, the energy density can still maintain 27.5 Wh kg-1. Moreover, the LIC displayed a high capacitance retention of 80.5% after 10000 cycles at 10 A g-1. The outstanding electrochemical performance can be contributed to the synergistic effect of the well-dispersed ultrafine TiO2 nanoparticles, the abundant mesoporous structure, and the conductive carbon networks.

Blockade of receptor for advanced glycation end products protects against systolic overload-induced heart failure after transverse aortic constriction in mice.

Heart failure is the consequence of sustained, abnormal neurohormonal and mechanical stress and remains a leading cause of death worldwide. The aim of this work was to identify whether blockade of receptor for advanced glycation end products (RAGE) protected against systolic overload-induced heart failure and investigate the possible underlying mechanism. It was found that RAGE mRNA and protein expression was up-regulated in cardiac tissues from mice subjected to pressure overload by transverse aortic constriction (TAC). Importantly, inhibition of RAGE by treatment with soluble RAGE (sRAGE) or FPS-ZM1 (a high-affinity RAGE-specific inhibitor) for 8 weeks attenuated cardiac remodeling (including cardiac hypertrophy and fibrosis), and dysfunction in mice exposed to TAC. Furthermore, treatment of TAC mice with sRAGE or FPS-ZM1 enhanced phosphorylation of AMPK and reduced phosphorylation of mTOR and protein expression of NFκB p65 in cardiac tissues. In addition, treatment of TAC mice with sRAGE or FPS-ZM1 abated oxidative stress, attenuated endoplasmic reticulum stress, and suppressed inflammation in cardiac tissues. These data demonstrated the benefits of blocking RAGE on the progression of systolic overload-induced heart failure in mice, which was possibly through modulating AMPK/mTOR and NFκB pathways.

Direct Reduction of Graphene Oxide by Ni Foam as a High-Capacitance Supercapacitor Electrode.

Three dimensional reduced graphene oxide (RGO)/Ni foam composites are prepared by a facile approach without using harmful reducing agents. Graphene oxide is reduced by Ni foam directly in its aqueous suspension at pH 2 at room temperature, and the resultant RGO sheets simultaneously assemble around the pillars of the Ni foam. The RGO/Ni foam composite is used as a binder-free supercapacitor electrode and exhibits high electrochemical properties. Its areal capacitance is easily tuned by varying the reduction time for different RGO loadings. When the reduction time increases from 3 to 15 days, the areal capacitance of the composite increases from 26.0 to 136.8 mF cm(-2) at 0.5 mA cm(-2). Temperature is proven to be a key factor in influencing the reduction efficiency. The composite prepared by 5 h reduction at 70 °C exhibits even better electrochemical properties than its counterpart prepared by 15 day reduction at ambient temperature. The 5 h RGO/Ni foam composite shows an areal capacitance of 206.7 mF cm(-2) at 0.5 mA cm(-2) and good rate performance and cycling stability with areal capacitance retention of 97.4% after 10000 cycles at 3 mA cm(-2). Further extending the reduction time to 9 h at 70 °C, the composite shows a high areal capacitance of 323 mF cm(-2) at 0.5 mA cm(-2). Moreover, the good rate performance and cycling stability are still maintained.

A New Feature Extraction Method of Near-Infrared Spectra Based on the Addition of Historical Data.

In traditional qualitative analysis of near-infrared (NIR) spectra, the stability of recognition models is decreased when new varieties of samples are added into the model. In order to improve the robustness of the model, a new feature extraction method based on the addition of historical data was put forward. The NIR training samples will be collected first, after that the historical data of the same species is added to constitute a larger and richer dataset. Then, the pretreated data of these training samples is projected to the feature space, which is constructed by feature extraction using partial least squares (PLS) based on the above dataset. Subsequently, orthogonal linear discriminant analysis (OLDA) is employed to extract features of the projected data. 18 varieties of corn seeds were taken as study subject, the comparative experiments with and without historical data are implemented respectively, and then the biomimetic pattern recognition (BPR) method is applied to verify the efficiency of the method proposed. The results suggest that the method adopted can improve the robustness of recognition model more effectively compared with the method without historical data. It maintains the high correct recognition ratios when new varieties are added into the model. Besides that, the recognition effect on test sets of the different days remains the same basically in the condition of same PLS dimensions. Therefore, the dimension of feature extraction can be set to some fixed values in recognition software. In this way, it can keep out of the trouble of manually modifying the optimal PLS parameter in recognition software if new varieties need to be added into the model. The experiment results of the thesis manifested the effectiveness of the proposed method.

Growth of nickel silicate nanoplates on reduced graphene oxide as layered nanocomposites for highly reversible lithium storage.

The combination of active materials with electrically conductive carbon materials and their contact efficiency are crucial for improving the electrochemical performances of active materials. Here, nickel silicate (NiSiOx) nanoplates are planted in situ on the surface of reduced graphene oxide (RGO) nanosheets to form a two dimensional face-to-face nanocomposite of NiSiOx/RGO for lithium storage. The face-to-face structure enhances the contact efficiency of NiSiOx with RGO, and thus leads to a higher reversible capacity and better rate performance of the NiSiOx/RGO nanocomposite than both carbon nanotube (CNT)@NiSiOx nanocables and NiSiOx. The layered NiSiOx/RGO nanocomposite exhibits a high reversible specific capacity of 797 mA h g(-1), which is 62% and 806% higher than those of CNT@NiSiOx nanocables and NiSiOx alone, respectively.