Realization of a 594 Wh kg-1 Lithium-Metal Battery Using a Lithium-Free V2 O5 Cathode with Enhanced Performances by Nanoarchitecturing.

To realize a high-energy lithium metal battery (LMB) using a high-capacity Li-free cathode, in this work, nanoplate-stacked V2 O5 with dominantly exposed (010) facets and a relatively short [010] length is proposed to be used as a cathode. The V2 O5 nanostructure can be fabricated via a modified hydrothermal method, including a Li+ crystallization inhibitor, followed by heat treatment. In particular, the enlargement of the favorable Li+ diffusion pathway in the [010] direction and the formation of a robust hierarchical nanoplate-stacked structure in the modified V2 O5 improves the electrochemical kinetics and stability; as a result, the nanoplate-stacked V2 O5 electrode exhibits a higher capacity and rate performance (258 mAh g-1 at 50 mA g-1 [0.17 C], 140 mAh g-1 at 1 A g-1 [3.4 C]) and cycling capability (79% capacity retention after 100 cycles at 0.5 C) compared to the previously reported V2 O5 nanobelt electrode. Notably, the LMB composed of Li//nanoplate-stacked V2 O5 full-cells shows high specific energy densities of 594.1 and 296.2 Wh kg-1 at 0.1 and 1.0 C, respectively, and a high Coulombic efficiency of 99.6% during 50 cycles.

Molecular characterization of Arabidopsis thaliana LSH1 and LSH2 genes.

BACKGROUND: Arabidopsis thaliana genome encodes ten DUF640 (short for domain of unknown function 640)/ALOG (short for Arabidopsis LSH1 and Oryza G1) proteins, also known as light-dependent short hypocotyl (LSH) proteins. While some of the LSH genes regulate organ boundary determination and shade avoidance response, the function of most of these genes remains largely unknown. OBJECTIVE: In this study, we aimed to characterize the function of AtLSH1 and AtLSH2 in Arabidopsis. METHODS: We overexpressed AtLSH1 and AtLSH2 (with or without the FLAG tag) in Arabidopsis Col-0 plants under the control of the 35S promoter. We also generated knockout or knockdown lines of these genes by miRNA-induced gene silencing (MIGS). We conducted intensive phenotypic analysis of these transgenic lines, and finally performed RNA-seq analysis of two AtLSH2 overexpression (OX) lines. RESULTS: Although AtLSH1 and AtLSH2 amino acid sequences showed high similarly, AtLSH2-OX lines showed much higher levels of their transcripts than those of AtLSH1-OX lines. Additionally, overexpression of AtLSH1 and AtLSH2 greatly inhibited hypocotyl elongation in a light-independent manner, and reduced both vegetative and reproductive growth. However, knockout or knockdown of both these AtLSH genes did not affect plant phenotype. Gene Ontology (GO) analysis of differentially expressed genes (DEGs) identified by RNA-seq revealed enrichment of the GO term 'response to stimulus', included phytohormone-responsive genes; however, genes responsible for the abnormal phenotypes of AtLSH2-OX lines could not be identified. CONCLUSION: Although our data revealed no close association between light and phytohormone signaling components, overexpression of AtLSH1 and AtLSH2 greatly reduced vegetative and reproductive growth of Arabidopsis plants. This property could be used to generate new plants by regulating expression of AtLSH1 and AtLSH2.

Graphene Quantum Dot Oxidation Governs Noncovalent Biopolymer Adsorption.

Graphene quantum dots (GQDs) are an allotrope of carbon with a planar surface amenable to functionalization and nanoscale dimensions that confer photoluminescence. Collectively, these properties render GQDs an advantageous platform for nanobiotechnology applications, including optical biosensing and delivery. Towards this end, noncovalent functionalization offers a route to reversibly modify and preserve the pristine GQD substrate, however, a clear paradigm has yet to be realized. Herein, we demonstrate the feasibility of noncovalent polymer adsorption to GQD surfaces, with a specific focus on single-stranded DNA (ssDNA). We study how GQD oxidation level affects the propensity for polymer adsorption by synthesizing and characterizing four types of GQD substrates ranging ~60-fold in oxidation level, then investigating noncovalent polymer association to these substrates. Adsorption of ssDNA quenches intrinsic GQD fluorescence by 31.5% for low-oxidation GQDs and enables aqueous dispersion of otherwise insoluble no-oxidation GQDs. ssDNA-GQD complexation is confirmed by atomic force microscopy, by inducing ssDNA desorption, and with molecular dynamics simulations. ssDNA is determined to adsorb strongly to no-oxidation GQDs, weakly to low-oxidation GQDs, and not at all for heavily oxidized GQDs. Finally, we reveal the generality of the adsorption platform and assess how the GQD system is tunable by modifying polymer sequence and type.

Identification of source-sink tissues in the leaf of Chinese cabbage (Brassica rapa ssp. pekinensis) by carbohydrate content and transcriptomic analysis.

BACKGROUND: A leaf of Chinese cabbage (Brassica rapa ssp. pekinensis) is composed of a photosynthetic blade and a non-photosynthetic large midrib; thus each leaf contains both source and sink tissues. This structure suggests that, unlike in other plants, source-sink metabolism is present in a single leaf of Chinese cabbage. OBJECTIVE: This study was designed to identify the transport route of photosynthetic carbon and to determine whether both source and sink tissues were present in a leaf. METHODS: Plant samples were collected diurnally. Their carbohydrate contents were measured, and a genome-wide transcriptome analysis was performed using the Br300K microarray. Expression profiles of selected genes were validated using qRT-PCR analysis. RESULTS: The presence of two contrasting tissues (blade as source and midrib as sink) in a leaf was demonstrated by (1) diurnal distribution patterns of starch and sucrose content; (2) Gene Ontology (GO) enrichment analysis of microarray data; (3) expression profiles of photosynthetic and sucrose biosynthetic genes; and (4) expression patterns of a variety of sugar transporter genes. CONCLUSION: Source and sink tissues were both present in Chinese cabbage leaves, but the midrib functioned as a sink tissue as well as a site exporting to roots and other sink tissues. Function of most genes discriminating between source and sink tissue appeared to be regulated largely at the post-transcriptional level, not at the transcriptional level.

Temperature-dependent water solubility of iodine-doped single-walled carbon nanotubes prepared using an electrochemical method.

We demonstrate that iodine-doping into single-walled carbon nanotubes (SWCNTs) can be effectively done using an electrochemical method. It is shown by in situ Raman measurements that the iodine-doping level can be easily and finely controlled because de-doping is also possible by changing the polarity. In situ synchrotron XRD measurements reveal that iodine molecules are mainly inserted into the hollow core of SWCNTs. The dispersion state of the iodine-doped SWCNTs in water as a function of temperature is also investigated. It is shown that the iodine-doped SWCNTs can be homogeneously dispersed in water at low temperature (ca. <15 °C).

Facile bottom-up synthesis of graphene nanofragments and nanoribbons by thermal polymerization of pentacenes.

To prepare nanosized graphene-like molecules of a defined structure (defined-width graphene nanoribbons or nanofragments) by a simple bottom-up method, thermal polymerization reactions of pentacenes were investigated. By optimizing heat treatment temperature and initial precursor weight, long-length fused pentacene molecules were successfully obtained at least up to octamer (n = 8). Here, the degree of polymerization was much larger than that of previously known polymerized pentacene systems (n = 2, 3). The structural and physical properties of the obtained fused pentacenes were characterized by Raman spectroscopy, X-ray diffraction, and photoluminescent spectroscopy. The fused pentacene system, examined using density functional theory calculations, was found to have unique electronic and magnetic structures originating from its characteristic size and edge structure. In addition, we performed detailed mass spectroscopic analysis that examined the fusing mechanism.