Robust 3.7 V-Na2/3_{2/3}[Cu1/3_{1/3}Mn2/3_{2/3}]O2_2 Cathode for Na-ion Batteries

Na-ion batteries (NIBs), which are recognized as a next-generation alternative technology for energy storage, still suffer from commercialization constraints due to the lack of low-cost, high-performance cathode materials. Since our first discovery of Cu$^{3+}$/Cu$^{2+}$ electrochemistry in 2014, numerous Cu-substituted/doped materials have been designed for NIBs. However for almost ten years, the potential of Cu$^{3+}$/Cu$^{2+}$ electrochemistry has been grossly underappreciated and normally regarded as a semielectrochemically active redox. Here, we re-synthesized P2-Na$_{2/3}$[Cu$_{1/3}$Mn$_{2/3}$]O$_2$ and reinterpreted it as a high-voltage, cost-efficient, air-stable, long-life, and high-rate cathode material for NIBs, which demonstrates a high operating voltage of 3.7 V and a completely active Cu$^{3+}$/Cu$^{2+}$ redox reaction. The 2.3 Ah cylindrical cells exhibit excellent cycling (93.1% capacity after 2000 cycles), high rate (97.2% capacity at 10C rate), good low-temperature performance (86.6% capacity at -30$^\circ$C), and high safety, based on which, a 56 V-11.5 Ah battery pack for E-bikes is successfully constructed, exhibiting stable cycling (96.5% capacity at the 800th cycle) and a long driving distance (36 km, tester weight 65 kg). This work offers a commercially feasible cathode material for low-cost, high-voltage NIBs, paving the way for advanced NIBs in power and stationary energy storage applications.Comment: 15 pages, 3 figures, 1 tabl

A Novel Efficient Method for Simulating Non-Stationary Random Processes Combining Generalized Harmonic Wavelet and Stochastic Harmonic Function

Integrating the general expression of the generalized harmonic wavelet (GHW)-based spectral representation method (SRM) and the idea of stochastic harmonic function (SHF), a novel stochastic generalized harmonic wavelet (SGHW) method for fully nonstationary stochastic processes, is established. The advantages of the proposed method are (1) a stochastic process with accurate probability information can be obtained by retaining fewer components. A smaller number of components greatly reduces the number of random variables. Fewer random variables also reduce the difficulty of random process analysis. The superior fitting effect between evolutionary power spectral density (EPSD) obtained from the samples using the SGHW method and the EPSD model proves the validity and effectiveness of the SGHW method. (2) The proposed method contains more accurate probability information and has a higher computational efficiency. The comparisons of relative errors and computational time between the SGHW method and the SRM demonstrate the accuracy and efficiency of the proposed method

Association of the Expression Level of miR-16 with Prognosis of Solid Cancer Patients: A Meta-Analysis and Bioinformatic Analysis

Objective. To assess the association between the expression level of miR-16 and prognosis of solid cancer patients by meta-analysis and bioinformatic analysis. Methods. PubMed, Web of Science, and Embase databases were searched until October 31, 2019, to identify eligible studies reporting the association of the miR-16 status with the prognosis of solid cancer patients. Hazard ratios (HRs) with 95% confidence intervals (CIs) were pooled, and a heterogeneity test was conducted. Sensitivity analysis and a publication bias test were also carried out. Furthermore, the miRpower database was used to validate the association. Results. Thirteen articles with 2303 solid cancer patients were included in the meta-analysis. Solid cancer patients with low expression level of miR-16 had shorter survival time (I2=84.0%, HR=1.47, 95% CI: 1.13-1.91, P=0.004). In the subgroup analyses of cancer sites, low miR-16 expression level was associated with poor prognosis in the reproductive system cancers (I2=33.3%, HR=1.24, 95% CI: 1.06-1.45, P=0.008). Sensitivity analysis suggested that the pooled HR was stable and omitting a single study did not change the significance of the pooled HR. Begg’s test and Egger’s test revealed no publication bias in the meta-analysis. In bioinformatic analysis, the significant association between miR-16 level and prognosis of patients with reproductive system cancers was further confirmed (HR=1.21, 95% CI: 1.03-1.42, P=0.017). Conclusion. Low expression level of miR-16 is an indicator for poor prognosis of solid cancer patients, particularly in reproductive system cancers

The complete mitochondrial genome of Holothuria fuscocinerea (Jaeger,1833)

In this study, the complete mitochondrial genome of Holothuria fuscocinerea was sequenced on an Illumina platform and assembled using NovoPlasty v. 2.7.1. It was submitted to NCBI GenBank and is available with accession number MN542416. The genome was 15,827 bp in size and contains 22 tRNA genes, 12 protein-coding genes, and 2 rRNA genes. The composition of A + T in Holothura spinifera mtDNA was 60.30%. Except ND6 and 5 tRNAs, the others are not on the H-strand. The phylogenetic relationship of 13 species of sea cucumber were analyzed using the neighbor-joining method by software MEGA5.0. Holothuria fuscocinerea was most closely related to Holothuria polii

Sample Entropy Based Net Load Tracing Dispatch of New Energy Power System

The high-proportion of renewable energies is gradually becoming one of the main power supply sources and bringing strong uncertainties to the power grid. In this paper, a sample entropy (SampEn) based net load tracing dispatch strategy with a specific thermal generating mode is proposed. In this strategy, renewable energies are fully and preferentially consumed by electric loads, turned to net loads, to maximize the utilization of renewable energies. SampEn theory is utilized to evaluate the complexity of net load time series, based on which, the traditional power generators trace the complexity of the net load flexibly. According to the SampEn, a specific generating model of thermal generators is determined and the cooperation between thermal generators and pumped storage is realized, aiming at reducing the ramp power of thermal generators and increasing the throughput of pumped storage. The experiment simulation is developed on the 10-unit test system. Results show that the ramping power of the thermal generators are reduced 43% and 13% in the two cases together with the throughput of pumped storage is increased 44% and 27% on the premise that the economy of the system is maintained and renewable energies are fully consumed. Therefore, the efficiency and reasonability of the proposed dispatch strategy are confirmed

The complete mitochondrial genome of Holothuria spinifera (Théel, 1866)

In this research, on an Illumina platform, the full mitochondrial genome of Holothuria spinifera was listed in a sequence and also gathered by using the NovoPlasty v. 2.7.1. It was submitted to NCBI GenBank, and is available with accession number MN816440. The size of genome was 15,812 bp and contained 12 protein-coding genes, two rRNA genes, and 22 tRNA genes. The configuration of A + T in Holothuria spinifera mtDNA was 60.44%. Except five tRNAs and ND6, others are placed on the H-strand. By using the Neighbor-Joining method by software MEGA5.0, the phylogenetic relationship of 13 species of sea cucumber was analyzed. Holothuria spinifera was most closely associated to Parastichopus parvimensis

Pseudocapacitive Energy Storage in Schiff Base Polymer with Salphen-Type Ligands

Salphen-type nickel Schiff bases Ni­(salphen), Ni­(CH₃-salphen), and Ni­(CH₃O-salphen) are synthesized and electropolymerized on stable ITO electrode, respectively. The morphologies of the three polymer electrodes were evaluated by field emission scanning electron microscopy (FESEM). X-ray photoelectron spectroscopy (XPS) measurements were carried out to shed light on the polymerization mode and energy storage mechanism. Meanwhile, kinetic analysis of the redox reactions was used to verify the pseudocapacitive mechanisms of charge storage. The result signals that the polymerization mode and the mechanism of energy storage are related to the reversible conversion of the azomethine nitrogen group (−NCH−) in the six-membered ring of Schiff base instead of the Ni²⁺/Ni³⁺ process. Meanwhile, the azomethine nitrogen group was found to be directly affected by the addition of the electron-donating group methyl and methoxy so that additional peaks of the CV curve are generated, making polyNi­(CH₃-salphen) and polyNi­(CH₃O-salphen) have higher doping level, charge transfer ability, and better pseudocapacitive energy storage property than the pristine polyNi­(salphen) polymer. At the current density of 0.05 mA cm^–2, the specific capacity of the polyNi­(CH₃O-salphen) electrode was about 216 F g^–1, higher than the specific capacity of 85 F g^–1 for polyNi­(salphen) and 133 F g^–1 for polyNi­(CH₃-salphen). In the meantime, the conductivity of polyNi­(CH₃O-salphen) is 108.7 S cm^–1 higher than that of the other two polymers. Therefore, the addition of the stronger methoxy group for electron-donating substituents makes polyNi­(CH₃O-salphen) have more excellent electrochemical kinetics and pseudocapacitive characteristics

Rational design of layered oxide materials for sodium-ion batteries

Sodium-ion batteries have captured widespread attention for grid-scale energy storage owing to the natural abundance of sodium. The performance of such batteries is limited by available electrode materials, especially for sodium-ion layered oxides, motivating the exploration of high compositional diversity. How the composition determines the structural chemistry is decisive for the electrochemical performance but very challenging to predict, especially for complex compositions. We introduce the "cationic potential" that captures the key interactions of layered materials and makes it possible to predict the stacking structures. This is demonstrated through the rational design and preparation of layered electrode materials with improved performance. As the stacking structure determines the functional properties, this methodology offers a solution toward the design of alkali metal layered oxides.</p

Intrinsic and spatially nonuniform ferromagnetism in Co-doped ZnO films

Co doped ZnO films have been deposited by a laser-molecular beam epitaxy system. X-ray diffraction and UV spectra analysis show that Co effectively substitutes the Zn site. Transmission electron microscopy (TEM) and secondary ion mass spectroscopy analysis indicate that there are no clusters. Co dopants are uniformly distributed in ZnO film. Ferromagnetic ordering is observed in all samples deposited under an oxygen partial pressure, PO2=10-3, 10-5, and 10-7 torr, respectively. However, the magnetization of PO2=10-3 and 10-5 is very small at room temperature. At low temperature, the ferromagnetic ordering is enhanced. Muon spin relaxation (μSR) measurements confirm the ferromagnetism in all samples, and the results are consistent with magnetization measurements. From μSR and TEM analysis, the film deposited under PO2=10-7 torr shows intrinsic ferromagnetism. However, the volume fraction of the ferromagnetism phase is approximately 70%, suggesting that the ferromagnetism is not carrier mediated. Resistivity versus temperature measurements indicate Efros variable range hopping dominates the conductivity. From the above results, we can confirm that a bound magnetic polaron is the origin of the ferromagnetism