Single-Atom Pd-N4 Catalysis for Stable Low-Overpotential Lithium-Oxygen Battery.

The critical challenge for Li-O2 batteries lies in the large charge overpotential, leading to undesirable side reactions and inferior cycle stability. Single-atom catalysts have shown promising prospects in expediting the kinetics of oxygen evolution reaction (OER) for Li-O2 batteries. However, a present practical drawback is the limited understanding of the correlation between the unique atomic structures and the OER mechanism. Herein, a template-assisted strategy is reported to synthesize atomically dispersed Pd anchored on N-doped carbon spheres as cathode catalysts. Benefiting from the well-defined Pd-N4 moiety, the morphology and distribution of Li2 O2 products are distinctly regulated with optimized decomposition reversibility. Theoretical simulations reveal that the unique configuration of Pd-N4 will contribute to the electron transfer from Pd atoms to the adjacent N atoms, which turns the originally electroneutral Pd into positively charged and downshifts the d-band center and therefore weakens its adsorption energy with the intermediates. The Li-O2 batteries with Pd SAs/NC cathode achieve a charge overpotential of only 0.24 V and sustainable low-overpotential cycling stability (500 mA g-1 ), and can retain a low charge voltage to a very high capacity of 10 000 mAh g-1 . This work provides some insights into designing efficient single-atom catalysts for stable low-overpotential Li-O2 batteries.

Maribacter aquimaris sp. nov., isolated from seawater adjacent to Fildes Peninsula, Antarctica.

A novel Gram-stain-negative, aerobic, and rod-shaped bacterium with gliding motility, named strain ANRC-HE7T, was isolated from the seawater of Biological Bay adjacent to Fildes Peninsula, Antarctica. The optimal growth of this strain occurred at 28 °C, pH 7.5, and in the presence of 1.0% (w/v) NaCl. Strain ANRC-HE7T can produce amylase and harbors gene clusters involved in cellulose degradation. Phylogenetic analysis based on the 16S rRNA gene sequence showed that strain ANRC-HE7T formed a distinct lineage within the genus Maribacter and was closely related to Maribacter luteus RZ05T (98.4% sequence similarity), Maribacter polysiphoniae LMG 23671T (98.3%), and Maribacter arenosus CAU 1321T (97.3%). However, digital DNA-DNA hybridization and average nucleotide identity values between strain ANRC-HE7T and closely related strains were 17.4-49.1% and 70.9-92.7%, much lower than the cutoff values of 70% and 95%, respectively. On the other hand, strain ANRC-HE7T shared characteristics with most type strains within the genus. Its respiratory quinone was MK-6. The major fatty acids were iso-C15:0, summed feature 3 (C16:1 ω7c and/or C16:1 ω6c), and anteiso-C15:0. The major polar lipids were phosphatidylethanolamine, two unidentified aminolipids, four unidentified phospholipids, and five unidentified glycolipids. The DNA G + C content of strain ANRC-HE7T was 40.1%. Based on the results of the biochemical, phylogenetic, and chemotaxonomic analyses, strain ANRC-HE7T is suggested to represent a novel species of the genus Maribacter, for which the name Maribacter aquimaris sp. nov. is proposed. The type strain is ANRC-HE7T (= MCCC 1K03787T = KCTC 72532T).

A Novel LiDAR-IMU-Odometer Coupling Framework for Two-Wheeled Inverted Pendulum (TWIP) Robot Localization and Mapping with Nonholonomic Constraint Factors.

This paper proposes a method to solve the problem of localization and mapping of a two-wheeled inverted pendulum (TWIP) robot on approximately flat ground using a Lidar-IMU-Odometer system. When TWIP is in motion, it is constrained by the ground and suffers from motion disturbances caused by rough terrain or motion shaking. Combining the motion characteristics of TWIP, this paper proposes a framework for localization consisting of a Lidar-IMU-Odometer system. This system formulates a factor graph with five types of factors, thereby coupling relative and absolute measurements from different sensors (including ground constraints) into the system. Moreover, we analyze the constraint dimension of each factor according to the motion characteristics of TWIP and propose a new nonholonomic constraint factor for the odometry pre-integration constraint and ground constraint factor in order to add them naturally to the factor graph with the robot state node on SE(3). Meanwhile, we calculate the uncertainty of each constraint. Utilizing such a nonholonomic constraint factor, a complete lidar-IMU-odometry-based motion estimation system for TWIP is developed via smoothing and mapping. Indoor and outdoor experiments show that our method has better accuracy for two-wheeled inverted pendulum robots.

Marinomonas flavescens sp. nov., isolated from seawater adjacent to Fildes Peninsula, Antarctica.

A Gram-negative bacterium, namely strain ANRC-JHZ47T, was isolated from a seawater sample collected at Biological Bay, Fildes Peninsula, Antarctica. Cells of strain ANRC-JHZ47T were rod-shaped and motile by a single polar flagellum. Strain ANRC-JHZ47T was aerobic, oxidase-negative, and catalase-positive. The strain grew at 4-37 °C (optimum, 25 °C), pH at 3.5-10.0 (optimum, pH 5.5) and in NaCl at 1-7.0 % (w/v; optimum, 2-3 %). Strain ANRC-JHZ47T used Q-8 as the predominant respiratory quinone. Its predominant fatty acids were C16 : 0 (21.9 %), C12 : 0 (12.6 %), C19 : 0cyclo ω8c (12.4 %), summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c; 13.1 %), C10 : 0 3-OH (11.3 %) and summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c; 6.0 %). Its major polar lipids were phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol, one unidentified aminolipid and five unknown polar lipids. The DNA G+C content was 42.6 mol%. Strain ANRC-JHZ47T showed the highest 16S rRNA gene sequence similarity to Marinomonas arenicola KMM 3893T (97.9 %), followed by Marinomonas primoryensis KMM 3633T (97.6 %), Marinomonas profundimaris D104T (97.2 %) and Marinomonas pollencensis IVIA-Po-185T (97.0 %). Furthermore, the average nucleotide identity values between strain ANRC-JHZ47T and M. arenicola KMM 3893T, M. primoryensis KMM 3633T and M. profundimaris D104T were 79.8, 74.0, and 74.1 %, respectively. The in silico DNA-DNA hybridization values between them were 22.5±2.5, 20.4±2.3 and 19.9±2.3 %, respectively. Based on the results of phenotypic and phylogenetic analyses, strain ANRC-JHZ47T is considered to represent a novel species of the genus Marinomonas, for which the name Marinomonas flavescens sp. nov. is proposed. The type strain is ANRC-JHZ47T (=MCCC 1K03604T=KCTC 72113T).

Constructing a Superlithiophilic 3D Burr-Microsphere Interface on Garnet for High-Rate and Ultra-Stable Solid-State Li Batteries.

Garnet-type solid-state electrolyte (SSE) Li6.5 La3 Zr1.5 Ta0.5 O12 attracts great interest due to its high ion conductivity and wide electrochemical window. But the huge interfacial resistance, Li dendrite growth, and low critical current density (CCD) block the practical applications. Herein, a superlithiophilic 3D burr-microsphere (BM) interface layer composed of ionic conductor LiF-LaF3 is constructed in situ to achieve a high-rate and ultra-stable solid-state lithium metal battery. The 3D-BM interface layer with a large specific surface area shows a superlithiophilicity and its contact angle with molten Li is only 7° enabling the facile infiltration of molten Li. The assembled symmetrical cell reaches one of the highest CCD (2.7 mA cm-2 ) at room temperature, an ultra-low interface impedance of 3 Ω cm2 , and a super-long cycling stability of 12 000 h at 0.1-1.5 mA cm-2 without Li dendrite growth. The solid-state full cells with 3D-BM interface show outstanding cycling stability (LiFePO4 : 85.4%@900 cycles@1 C; LiNi0.8 Co0.1 Mn0.1 O2 :89%@200 cycles@0.5 C) and a high rate capacity (LiFePO4 :135.5mAh g-1 at 2 C). Moreover, the designed 3D-BM interface is quite stable after 90 days of storage in the air. This study offers a facile strategy to address the critical interface issues and accelerate the practical application of garnet-type SSE in high performance solid-state lithium metal batteries.

The vital role of buffer anions in the antioxidant activity of CeO2 nanoparticles.

Cerium oxide (CeO(2)) nanoparticles display excellent antioxidant properties by scavenging free radicals. However, some studies have indicated that they can cause an adverse response by generating reactive oxygen species (ROS). Hence, it is important to clarify the factors that affect the oxidant/antioxidant activities of CeO(2) nanoparticles. In this work, we report the effects of different buffer anions on the antioxidant activity of CeO(2) nanoparticles. Considering the main anions present in the body, Tris-HCl, sulfate, and phosphate buffer solutions have been used to evaluate the antioxidant activity of CeO(2) nanoparticles by studying their DNA protective effect. The results show that CeO(2) nanoparticles can protect DNA from damage in Tris-HCl and sulfate systems, but not in phosphate buffer solution (PBS) systems. The mechanism of action has been explored: cerium phosphate is formed on the surface of the nanoparticles, which interferes with the redox cycling between Ce(3+) and Ce(4+). As a result, the antioxidant activity of CeO(2) nanoparticles is greatly affected by the external environment, especially the anions. These results may provide guidance for the further practical application of CeO(2) nanoparticles.

Improving Cycling Stability and Rate Capability of High-Voltage LiCoO2 Through an Integration of Lattice Doping and Nanoscale Coating.

High-voltage LiCoO2 has attracted much interest owing to the high specific energy density. But the poor cycling performance and inferior rate capacity of LiCoO2 at a high voltage (≥4.5 V) has restricted the practical applications. Herein, we propose to improve the electrochemical performances of LiCoO2 at high voltage through a synergy of Al-doping and Li2TiO3-coating. In compared to bare LiCoO2, Al-doped LiCoO2 and Li2TiO3-coated LiCoO2, the cycle performance, the rate capability and the polarization of Al-doped and Li2TiO3-coated LiCoO2 shows a larger improvement, which can be attributed to the synergic effects of Al-doping and Li2TiO3-coating. Firstly, Al doping expands the interlayer spacing which decreases the Li-ion diffusion barrier and enhances the coefficient of Li-ion diffusion. This benefits to the rate capability. Secondly, Al doping enhances the layered structure stability due to the larger Al-O bonding energy (ΔH298 Kt (Al-O) = 512 kJmol-1) than that of Co-O (ΔH298 Kt (Co-O) = 368 kJmol-1). Thirdly, the coating layer of Li2TiO3 mitigates the surface side reactions and further enhances the cycling performance. Moreover, the coating layer of Li2TiO3 as a Li+-conductor is also favorable to the Li+ diffusion and the rate capability. This synergic strategy can also be extended to the modification of other cathode materials.

An electrochemical DNA biosensor for evaluating the effect of mix anion in cellular fluid on the antioxidant activity of CeO2 nanoparticles.

CeO2 nanoparticles are of particular interest as a novel antioxidant for scavenging free radicals. However, some studies showed that they could cause cell damage or death by generating reactive oxygen species (ROS). Up to now, it is not well understood about these paradoxical phenomena. Therefore, many attentions have been paid to the factors that could affect the antioxidant activity of CeO2 nanoparticles. CeO2 nanoparticles would inevitably encounter body fluid environment for its potential medical application. In this work the antioxidant activity behavior of CeO2 nanoparticles is studied in simulated cellular fluid, which contains main body anions (HPO4(2-), HCO3(-), Cl(-) and SO4(2-)), by a method of electrochemical DNA biosensor. We found that in the solution of Cl(-) and SO4(2-), CeO2 nanoparticles can protect DNA from damage by hydroxyl radicals, while in the presence of HPO4(2-) and HCO3(-), CeO2 nanoparticles lose the antioxidant activity. This can be explained by the cerium phosphate and cerium carbonate formed on the surface of the nanoparticles, which interfere with the redox cycling between Ce(3+) and Ce(4+). These results not only add basic knowledge to the antioxidant activity of CeO2 nanoparticles under different situations, but also pave the way for practical applications of nanoceria. Moreover, it also shows electrochemical DNA biosensor is an effective method to explore the antioxidant activity of CeO2 nanoparticles.

Effects of Nano-CeO2 with Different Nanocrystal Morphologies on Cytotoxicity in HepG2 Cells.

Cerium oxide nanoparticles (nano-CeO2) have been reported to cause damage and apoptosis in human primary hepatocytes. Here, we compared the toxicity of three types of nano-CeO2 with different nanocrystal morphologies (cube-, octahedron-, and rod-like crystals) in human hepatocellular carcinoma cells (HepG2). The cells were treated with the nano-CeO2 at various concentrations (6.25, 12.5, 25, 50, 100 µg/mL). The crystal structure, size and morphology of nano-CeO2 were investigated by X-ray diffractometry and transmission electron microscopy. The specific surface area was detected using the Brunauer, Emmet and Teller method. The cellular morphological and internal structure were observed by microscopy; apoptotic alterations were measured using flow cytometry; nuclear DNA, mitochondrial membrane potential (MMP), reactive oxygen species (ROS) and glutathione (GSH) in HepG2 cells were measured using high content screening technology. The scavenging ability of hydroxyl free radicals and the redox properties of the nano-CeO2 were measured by square-wave voltammetry and temperature-programmed-reduction methods. All three types of nano-CeO2 entered the HepG2 cells, localized in the lysosome and cytoplasm, altered cellular shape, and caused cytotoxicity. The nano-CeO2 with smaller specific surface areas induced more apoptosis, caused an increase in MMP, ROS and GSH, and lowered the cell's ability to scavenge hydroxyl free radicals and antioxidants. In this work, our data demonstrated that compared with cube-like and octahedron-like nano-CeO2, the rod-like nano-CeO2 has lowest toxicity to HepG2 cells owing to its larger specific surface areas.