Summary
Plant protoplasts are useful for assessing the efficiency of clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR‐associated protein 9 (Cas9) mutagenesis. We improved the ...process of protoplast isolation and transfection of several plant species. We also developed a method to isolate and regenerate single mutagenized Nicotianna tabacum protoplasts into mature plants. Following transfection of protoplasts with constructs encoding Cas9 and sgRNAs, target gene DNA could be amplified for further analysis to determine mutagenesis efficiency. We investigated N. tabacum protoplasts and derived regenerated plants for targeted mutagenesis of the phytoene desaturase (NtPDS) gene. Genotyping of albino regenerants indicated that all four NtPDS alleles were mutated in amphidiploid tobacco, and no Cas9 DNA could be detected in most regenerated plants.
We demonstrated for the first time that Ag-nanoparticle-decorated SiO2 nanospheres (NSs) may display noticeable photocatalytic activities upon surface plasmon resonance (SPR) excitation. The samples ...were prepared by reacting SiO2 NSs with AgNO3 in the seed-mediated growth process, from which the Ag particle size and decoration density can be readily controlled. The dependence of the SPR-mediated photocatalytic performance of Ag-decorated SiO2 NSs on the Ag morphology was investigated and presented. The as-prepared Ag-decorated SiO2 NSs showed a significantly red shifted and relatively broad SPR absorption when compared with the individually dispersed Ag nanoparticles. Owing to the considerably broad SPR absorption that spanned from the visible to the near-infrared region, Ag-decorated SiO2 NSs surpassed N-doped P-25 TiO2 powder and individually dispersed Ag nanoparticles in photocatalytic activity, demonstrating their potential as an active photocatalyst in nearly all the current photocatalysis applications. Furthermore, the result of performance evaluation under natural sunlight shows that the present Ag-decorated SiO2 NSs can be used as highly efficient photocatalysts that may practically harvest energy from sunlight. The current study provides a new paradigm for designing plasmonic metal nanostructures that can effectively absorb the entire solar spectrum and beyond for solar fuel generation.
Al-free and Al-doped V2O5 nanostructures were synthesized by a thermal-chemical vapor deposition (CVD) process on Si(100) at 850 °C under 1.2 × 10−1 Torr via a vapor-solid (V-S) mechanism. X-ray ...diffraction (XRD), Raman, and high-resolution transmission electron microscopy (HRTEM) confirmed a typical orthorhombic V2O5 with the growth direction along 110-direction of both nanostructures. Metallic Al, rather than Al3+-ion, was detected by X-ray photoelectron spectroscopy (XPS), affected the V2O5 crystallinity. The photoluminescence intensity of V2O5 nanostructure at 1.77 and 1.94 eV decreased with the increasing Al-dopant by about 61.6% and 59.9%, attributing to the metallic Al intercalated between the V2O5-layers and/or filled in the oxygen vacancies, which behaved as electron sinks. Thus the Al-doped V2O5 nanostructure shows the potential applications in smart windows and the electrodic material in a Li-ion battery.
Atomic layer deposition (ALD) technology consisting of periodically repeated series of self-limited surface reactions is a CVD technique for the well-controlled deposition of inorganic layers with ...thickness in the nanometer scale which has been widely used in the semiconductor industry. In this study, a novel process to fabricate TiO2 nano-layer with high uniformity by ALD on the graphite negative electrode of lithium battery is reported. We found that under accurate thickness control, a TiO2 plated graphite electrode shows better performance in cycle life, compared with the pristine graphite. Electrochemical impedance spectroscopy (EIS) results showed that after 60 cycles, the cell resistance of the TiO2 plated electrode decreased, while that of normal graphite electrode increased significantly. The enhanced performance of the electrode may be attributed to the TiO2 plating, which suppressed the increase of resistance during the prolonged cycle.
► Atomic layer deposition is an effective process to fabricate TiO2 nano-layer. ► The high uniformity TiO2-deposited electrode is applied in lithium ion battery. ► TiO2 deposited electrode enhances the electrochemical performance of Li-ion cells. ► Electrode with TiO2 shows smaller resistance than controlled one after cell cycling. ► The resistance suppression results in a good cycle stability of the Li-ion cell.
•Nano-sized Li4Ti5O12 (LTO)-coated graphite core–shell prepared by sol–gel process.•LTO-coated graphite is used in Li-ion battery to improve the cycle life under 55°C.•Graphite coated with LTO shows ...smaller resistance than graphite after cell cycling.•The LTO coating suppress the disorder of SP2 structure in graphite during cycling.•Resistance and structure stabilization results in good cycle life of the Li-ion cell.
In this study, we synthesized and characterized Li4Ti5O12 (LTO)-coated graphite as an anode material for Li-batteries. The surface of graphite powders was uniformly coated by the LTO nanoparticles to form a core–shelled structure via a sol–gel process, followed by calcination. The average size of graphite core was 20μm while the thickness of LTO shell was 60nm to 100nm. We found that LTO-coated graphite has better rate-capability and cycle life at RT and 55°C, compared with the pristine graphite. The electrochemical impedance spectroscopy (EIS) results of the cell with LTO-coated graphite anode showed a significant suppression of the impedance rise after 60 cycles. In addition, the Raman spectrum showed that after 60 charge–discharge cycles at 55°C, the ID/IG ratio of the LTO-coated graphite electrode increased slightly, while that of the pristine graphite electrode increased significantly. The batteries with LTO-coated graphite anode exhibited excellent cyclic ability and high temperature performance.
Summary
The chloroplast NAD(P)H dehydrogenase‐like (NDH) complex consists of about 30 subunits from both the nuclear and chloroplast genomes and is ubiquitous across most land plants. In some ...orchids, such as Phalaenopsis equestris, Dendrobium officinale and Dendrobium catenatum, most of the 11 chloroplast genome‐encoded ndh genes (cp‐ndh) have been lost. Here we investigated whether functional cp‐ndh genes have been completely lost in these orchids or whether they have been transferred and retained in the nuclear genome. Further, we assessed whether both cp‐ndh genes and nucleus‐encoded NDH‐related genes can be lost, resulting in the absence of the NDH complex. Comparative analyses of the genome of Apostasia odorata, an orchid species with a complete complement of cp‐ndh genes which represents the sister lineage to all other orchids, and three published orchid genome sequences for P. equestris, D. officinale and D. catenatum, which are all missing cp‐ndh genes, indicated that copies of cp‐ndh genes are not present in any of these four nuclear genomes. This observation suggests that the NDH complex is not necessary for some plants. Comparative genomic/transcriptomic analyses of currently available plastid genome sequences and nuclear transcriptome data showed that 47 out of 660 photoautotrophic plants and all the heterotrophic plants are missing plastid‐encoded cp‐ndh genes and exhibit no evidence for maintenance of a functional NDH complex. Our data indicate that the NDH complex can be lost in photoautotrophic plant species. Further, the loss of the NDH complex may increase the probability of transition from a photoautotrophic to a heterotrophic life history.
Significance statement
The NDH complex is composed of multiple genes encoded by the chloroplast and nuclear genomes. Some photoautotrophs have been shown to lack all the chloroplast genome‐encoded ndh genes but the genes in the nucleus have never been assessed. Through sequencing the ndh‐complete orchid genome, Apostasia odorata, we showed that the missing ndh genes in ndh‐free orchids are not transferred to the nucleus, and the nuclear NDH‐related genes were also lost resulting in no NDH complex.
The cyanobacterial phylum encompasses oxygenic photosynthetic prokaryotes of a great breadth of morphologies and ecologies; they play key roles in global carbon and nitrogen cycles. The chloroplasts ...of all photosynthetic eukaryotes can trace their ancestry to cyanobacteria. Cyanobacteria also attract considerable interest as platforms for “green” biotechnology and biofuels. To explore the molecular basis of their different phenotypes and biochemical capabilities, we sequenced the genomes of 54 phylogenetically and phenotypically diverse cyanobacterial strains. Comparison of cyanobacterial genomes reveals the molecular basis for many aspects of cyanobacterial ecophysiological diversity, as well as the convergence of complex morphologies without the acquisition of novel proteins. This phylum-wide study highlights the benefits of diversity-driven genome sequencing, identifying more than 21,000 cyanobacterial proteins with no detectable similarity to known proteins, and foregrounds the diversity of light-harvesting proteins and gene clusters for secondary metabolite biosynthesis. Additionally, our results provide insight into the distribution of genes of cyanobacterial origin in eukaryotic nuclear genomes. Moreover, this study doubles both the amount and the phylogenetic diversity of cyanobacterial genome sequence data. Given the exponentially growing number of sequenced genomes, this diversity-driven study demonstrates the perspective gained by comparing disparate yet related genomes in a phylum-wide context and the insights that are gained from it.
Pristine, and In-, Sn-, and (In, Sn)-doped Bi2Se3 nanoplatelets synthesized on Al2O3(100) substrate by a vapor–solid mechanism in thermal CVD process via at 600 °C under 2 × 10−2 Torr. XRD and HRTEM ...reveal that In or Sn dopants had no effect on the crystal structure of the synthesized rhombohedral-Bi2Se3. FPA–FTIR reveals that the optical bandgap of doped Bi2Se3 was 26.3%, 34.1%, and 43.7% lower than pristine Bi2Se3. XRD, FESEM–EDS, Raman spectroscopy, and XPS confirm defects (In3+Bi3+), (In3+V0), (Sn4+Bi3+), (V0Bi3+), and (Sn2+Bi3+). Photocurrent that was generated in (In,Sn)-doped Bi2Se3 under UV(8 W) and red (5 W) light revealed stable photocurrents of 5.20 × 10−10 and 0.35 × 10−10 A and high Iphoto/Idark ratios of 30.7 and 52.2. The rise and fall times of the photocurrent under UV light were 4.1 × 10−2 and 6.6 × 10−2 s. Under UV light, (In,Sn)-dopedBi2Se3 had 15.3% longer photocurrent decay time and 22.6% shorter rise time than pristine Bi2Se3, indicating that (In,Sn)-doped Bi2Se3 exhibited good surface conduction and greater photosensitivity. These results suggest that In, Sn, or both dopants enhance photodetection of pristine Bi2Se3 under UV and red light. The findings also suggest that type of defect is a more important factor than optical bandgap in determining photo-detection sensitivity. (In,Sn)-doped Bi2Se3 has greater potential than undoped Bi2Se3 for use in UV and red-light photodetectors.
During the voltammetry of carbon supports for proton exchange membrane fuel cells (PEMFCs), including commercial carbon blacks, graphitized carbon black and multi-wall carbon nanotubes (MWNTs), in ...deaerated 0.5
M H
2SO
4 solution results in mass changes as observed by using in situ electrochemical quartz crystal microbalance (EQCM). The mass change and corrosion onset potential during electrochemical carbon corrosion indicate that oxides are formed and accumulated on the carbon surface, leading to an increase in mass. A decrease in the mass is associated with carbon loss from the gasification of carbon surface oxides into carbon dioxide. High BET surface area carbon blacks ECP600 and ECP 300 have a carbon loss of 0.0245
ng
cm
−2
s
−1 and 0.0144
ng
cm
−2
s
−1 and as compared to 0.0115
ng
cm
−2
s
−1 for low surface area support XC-72 and so they are less resistant to corrosion. Graphitized XC-72 and MWNTs, with higher graphitization have higher carbon corrosion onset potential at 1.65
V and 1.62
V and appear to be more intrinsically resistant to corrosion.
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