GaN based ultraviolet laser diodes

In the past few years,many groups have focused on the research and development of GaN-based ultraviolet laser diodes(UV LDs).Great progresses have been achieved even though many challenges exist.In this article,we analyze the challenges of developing GaN-based ultraviolet laser diodes,and the approaches to improve the performance of ultraviolet laser diode are reviewed.With these techniques,room temperature(RT)pulsed oscillation of AlGaN UVA(ultraviolet A)LD has been realized,with a lasing wavelength of 357.9 nm.Combining with the suppression of thermal effect,the high output power of 3.8 W UV LD with a lasing wavelength of 386.5 nm was also fabricated.

Electrolyte Strategies Toward Optimizing Zn Anode for Zinc-Ion Batteries

Zinc-ion batteries(ZIBs)with low cost and high safety have become potential candidates for large-scale energy storage.However,the knotty Zn anode issues such as dendritic growth,hydrogen evolution reaction(HER)and corrosion and passivation are still unavoidable,which greatly limits the wide applications of ZIBs.The states and additives of electrolytes are closely related to these problems.However,there is a lack of systematic understanding and discussion about the intrinsic connection between the states and additives of electrolyte and Zn anode issues.In this review,the basic principles of dendritic growth,HER and corrosion and passivation are fi rstly introduced,and then,electrolyte optimization strategies with the corresponding electrochemical properties are systematically summarized.In particular,the action mechanism of electrolyte additives and the electrolyte states for Zn anode optimization is analyzed in detail.Finally,some unique views on the improvement of electrolyte for Zn anode optimization are put forward,which is expected to provide a certain professional reference for designing high-performance ZIBs.

Ectopic Overexpression of EuCHIT30.7 Improves Nicotiana tabacum Resistance to Powdery Mildew

Various strains of powdery mildew(PM),a notorious plant fungal disease,are prevalent and pose a significant threat to plant health.To control PM,transgenic technology can be used to cultivate more resistant plant varieties.In the present study,we utilized the rapid amplification of cDNA ends(RACE)technique to clone the full-length cDNA sequence of the EuCHIT30.7 gene to explore plant genes with disease resistance functions.Bioinformatics analysis revealed that this gene belongs to the GH18 family and is classified as a class III chitinase.The EuCHIT30.7 gene is expressed throughout the Eucommia ulmoides plant,with the most abundant expression in male flowers.Subcellular localization analysis indicated that the protein encoded by this gene was detected within both the cell membrane and cytoplasm.Upon PM inoculation,overexpression of EuCHIT30.7 in tobacco plants led to a significantly reduced relative lesion area and a decreased spore count compared to both wild-type and empty vector control plants.Activities of the protective enzymes,namely,peroxidase(POD),superoxide dismutase(SOD),catalase(CAT),and phenylalaninammo-nialyase(PAL),in tobacco plants overexpressing EuCHIT30.7 were significantly greater than those in wild-type and empty vector tobacco plants.Furthermore,the rate of increase in malondialdehyde(MDA)content was significantly lower in tobacco plants expressing EuCHIT30.7 compared to control tobacco plants.In EuCHIT30.7 transgenic tobacco,the expression of pathogen-related protein genes,namely,PR2,PR5,PR1a,PDF1.2,and MLP423,along with the tobacco PM negative regulatory gene,MLO2,were significantly higher compared to control tobacco plants.These findings suggested that EuCHIT30.7 significantly enhances the resistance of tobacco to PM.

Cloning and Function Identification of a Phytoene Desaturase Gene from Eucommia ulmoides

The phytoene desaturase(PDS)encodes a crucial enzyme in the carotenoid biosynthesis pathway.Silencing or inhibiting PDS expression leads to the appearance of mottled,chlorosis,or albino leaves.In this study,the CDS sequence of EuPDS(Eucommia ulmoides Phytoene Desaturase)was first cloned and then PDS was silenced in Nicotiana benthamiana.Result showed the expression level of EuPDS in leaves was higher than that in the roots and stems.In N.benthamiana leaves,which were treated by Agrobacterium for 24 h,photo-bleaching was shown on the fresh leaves one week after injection and the transcript level of PDS was down-regulated during the period of emersion.This suggested that EuPDS could silence PDS of N.benthamiana,so as to cause the phenotype of leaf whitening.PDS is the main reporter gene involved in virus-induced gene silencing(VIGS).This study offered molecular evidence for identifying PDS gene involved in Carotenoid’s biosynthesis pathway and the regulation networks in E.ulmides.It also laid a useful foundation for study on leaf discoloration mechanism of other woody plants.

Overexpression ofβ-1,4-Glucanase Gene EuEG1 Improves Micrografting of Eucommia ulmoides

Adventitious root formation poses a major constraint on the tissue culture and genetic transformation of Eucommia ulmoides.Micrografting offers a new method for the transplantation of genetic transformation,and its success depends on the formation of graft unions.This study used transgenic rootless test-tube seedlings as scions and seedlings from seed as rootstocks during micrografting to avoid the rooting issues that occur during tissue culture and to investigate the role of the EuEG1 gene in the graft healing process.We found that the EuEG1 gene is a vital regulator of graft,and its overexpression contributes to the survival of Eucommia ulmoides micrografting.The EuEG1 gene transgenic plants(TP)used as scions for micrografting presented a significantly higher survival rate than the wild type(WT)and empty vector(EV)regenerated scions.During the grafting healing process,the expression of the EuEG1 gene was higher during the period of callus proliferation,suggesting that the EuEG1 gene was involved in the graft healing process.Histological observation revealed that more calluses tissue appeared at the junction of transgenic scions,and the connection with the rootstock was stronger,which benefits wound healing.These results provide new insights into Eucommia ulmoides micrografting and indicate that the EuEG1 gene can promote wound healing and improve the micrografting survival rate.

Room-temperature continuous-wave operation of GaN-based blue-violet laser diodes with a lifetime longer than 1000h

GaN-based continuous-wave operated blue-violet laser diodes(LDs) with long lifetime are demonstrated, which are grown on a c-plane GaN substrate by metal organic chemical vapor deposition with a 10 × 600 μm^2 ridge waveguide structure.The electrical and optical characteristics of a blue-violet LD are investigated under direct-current injection at room temperature(25 °C). The stimulated emission wavelength and peak optical power of the LD are around 413 nm and over 600 mW, respectively.In addition, the threshold current density and voltage are as small as 1.46 kA/cm^2 and 4.1 V, respectively. Moreover, the lifetime is longer than 1000 hours under room-temperature continuous-wave operation.

Genome-level diversification of eight ancient tea populations in the Guizhou and Yunnan regions identifies candidate genes for core agronomic traits

The ancient tea plant,as a precious natural resource and source of tea plant genetic diversity,is of great value for studying the evolutionary mechanism,diversification,and domestication of plants.The overall genetic diversity among ancient tea plants and the genetic changes that occurred during natural selection remain poorly understood.Here,we report the genome resequencing of eight different groups consisting of 120 ancient tea plants:six groups from Guizhou Province and two groups from Yunnan Province.Based on the 8,082,370 identified high-quality SNPs,we constructed phylogenetic relationships,assessed population structure,and performed genome-wide association studies(GWAS).Our phylogenetic analysis showed that the 120 ancient tea plants were mainly clustered into three groups and five single branches,which is consistent with the results of principal component analysis(PCA).Ancient tea plants were further divided into seven subpopulations based on genetic structure analysis.Moreover,it was found that the variation in ancient tea plants was not reduced by pressure from the external natural environment or artificial breeding(nonsynonymous/synonymous=1.05).By integrating GWAS,selection signals,and gene function prediction,four candidate genes were significantly associated with three leaf traits,and two candidate genes were significantly associated with plant type.These candidate genes can be used for further functional characterization and genetic improvement of tea plants.

A 357.9 nm GaN/AlGaN multiple quantum well ultraviolet laser diode

Ultraviolet(UV)and deep-UV light emitters are prom-ising for various applications including bioagent detection,wa-ter and air purification,dermatology,high-density optical stor-age,and lithography.However,to achieve shorter UV laser di-odes(LDs),especially for the LDs with lasing wavelength less than 360 nm,requires high AlN mole fraction AlGaN clad-ding layer(CL)and waveguide(WG)layers,which usually leads to generate cracks in AlGaN epilayer due to lack of lat-tice-matched substrates.Meanwhile,due to high resistivity of high AlN mole fraction Mg doped AlGaN layers,only few groups have reported GaN-based LDs with emission wavelength shorter than 360 nm[1−8],and up to now,there is no room temperature continuous-wave(CW)operation UV LDs with a lasing wavelength shorter than 360 nm ever repor-ted.Previously,we have reported a UV LD with lasing wavelength of 366 nm[9].In this paper,a higher AlN mole frac-tion of AlGaN WG layers is employed to shorten the LD emis-sion wavelength to less than 360 nm.A lasing wavelength of 357.9 nm is achieved.

GaN-based blue laser diode with 6.0 W of output power under continuous-wave operation at room temperature

In this work,we reported the room-temperature continuous-wave operation of 6.0 W GaN-based blue laser diode(LD),and its stimulated emission wavelength is around 442 nm.The GaN-based high power blue LD is grown on a c-plane GaN substrate by metal organic chemical vapor deposition(MOCVD),and the width and length of the ridge waveguide structure are 30 and 1200μm,respectively.The threshold current is about 400 mA,and corresponding threshold current density is 1.1 kA/cm2.

Ⅲ-nitride based ultraviolet laser diodes

In recent years,because of their small size,high efficiency and environment-friendly advantages,Ⅲ-nitride based ultraviolet(UV)light-emitting diodes(LEDs)have been widely used in many areas to substitute for mercury lamps,such as in 3D printing,curing and sterilization.Ⅲ-nitride alloys cover the whole UV spectrum which is comprised of UV-A(320–400 nm),UV-B(280–320 nm)and UV-C(200–280 nm)by controlling Al/Ga/In content.In addition,Ⅲ-nitride based UV laser diodes(LDs)also have some potential applications in the case of high-power-density,narrow-spectrum,good-directional lighting.However,Ⅲ-nitride based UV laser diodes still have many challenges such as poor crystal quality and low hole concentration in p-type AlGaN.

Large scale identification of SSR marker in perilla by next generation sequencing

Perilla frutescens (L.) is an edible, medicinal crop, and most popular in East Asia. Its molecular breeding and research are hampered by the paucity of molecular markers. Simple sequence repeat (SSR) markers are ubiquitous and widely used in eukaryotic genomes. EST-SSRs identification of perilla was performed in 116,387 reads generated by Illumina paired-end sequencing technology. In total 25,449 unigenes containing SSR and 33,867 SSR loci were identified, and 19,400 primer pairs were designed. Polymorphism of SSR primers was conducted by searching for insertions and deletions (INDELs), and 1,567 unique SSRs were predicted. Totally, 200 SSR primer pairs were selected for polymorphic validation among 23 perilla accessions. Results showed that 175 primer pairs produced amplicons, and 30 pairs exhibited polymorphism. Polymorphic ratio was higher by using INDEL method than using conventional primers. Phylogenetic analysis showed the 2 distinct groups: P. frutescens var. frutescens and P. frutescens var. crispa. Wrinkled leaf trait and seed trait were distinct between these 2 groups. However, no clear leaf color or geographic relationship was detected. The large scale development and identification of SSR marker in this research laid a foundation for genetic analysis and marker assisted breeding of cultivated perilla.

DWARF and SMALL SEED1,a Novel Allele of OsDWARF,Controls Rice Plant Architecture,Seed Size,and Chlorophyll Biosynthesis

Plant architecture is a vital agronomic trait to control yield in rice(Oryza sativa L.).A dwarf and small seed 1(dss1)mutant were obtained from the ethyl methanesulfonate(EMS)mutagenized progeny of a Guizhou glutinous landrace cultivar,Lipingzabianhe.The dss1 mutant displayed phenotypes similar to those of brassinosteroid(BR)deficient mutants,such as dwarfing,dark green and rugose erect leaves,small seeds,and loner neck internode panicles with primary branching.In our previous study,the underlying DSS1 gene was isolated,a novel allele of OsDWARF(OsBR6ox)that encodes a cytochrome P450 protein involved in the BR biosynthetic pathway by MutMap technology.In this work,we confirmed that a Thr335Ile amino acid substitution residing in DSS1/OsDWARF was responsible for the dwarf,panicle architecture,and small seed phenotypes in the dss1 mutants by genetic transformation experiments.The overexpression of OsDWARF in the dss1 mutant background could not only recover dss1 to the normal plant height and panicle architecture but also rescued normal leaf angles,seed size,and leaf color.Thus,the specific mutation in DSS1/OsDWARF influenced plant architecture,seed size,and chlorophyll biosynthesis.

Cloning and Bioinformatics Analysis of FaPHYC Gene in Tall Fescue (Festuca arundinacea)

The cDNA of PHYC gene of tall fescue ( Festuca arundinacea ) was cloned by RT-PCR,named FaPHYC.The sequence was analyzed by bioinformatic software,and the results showed that the full-length cDNA(3816 bp) was obtained with an open reading frame predicated to be 3 411 bp,which encoded 1 136 amino acids.By BLASTP analysis,the N-terminal of FaPHYC was composed of GAF and pPhytochrome domains,and its C-terminal included two repeated PAS domains,one histidine kinase A domain and one histidine kinase-like ATPase domain.The phylogenetic analysis showed that FaPHYC was closely related to PHYCs from other Gramineae plants.The qRT-PCR results showed that FaPHYC expression was regulated by drought stress,heat stress,salt stress and nitrogen stress.The real-time quantitative PCR assay showed the expression of FaPHYC in tall fescue seedlings was continuously up-regulated during the light period and down-regulated in the dark.The results suggest that FaPHYC is photoperiod sensitive and plays a functional role in flowering regulation by photoperiod in tall fescue.The FaPHYC gene was cloned and reported from tall fescue for the first time,which lays a foundation for the investigation of the stress mechanism of FaPHYC in tall fescue plant.

Identification and Characterization of a Novel Yellow Leaf Mutant yl1 in Rice

Leaf-color mutants play an important role in the study of chlorophyll metabolism,chloroplast development,and photosynthesis system.In this study,the yellow leaf 1(yl1)rice mutant was identified from the ethyl methane sulfonate-treated mutant progeny of Lailong,a glutinous japonica rice landrace cultivated in Guizhou Province,China.Results showed that yl1 exhibited yellow leaves with decreased chlorophyll content throughout the growth period.Chloroplast development in the yl1 mutant was disrupted,and the grana lamellae was loosely packed and disordered.RNA sequencing and real-time quantitative polymerase chain reaction(qRT-PCR)analysis revealed that the chlorophyll synthesis-related genes OsCHLH,OsCHLM,OsCHLG,PORB,and YGL8,as well as the chloroplast development-related genes FtsZ,OsRpoTp,and RbcL,were down-regulated in the yl1 mutant.Genetic analysis revealed that the yellow leaf phenotype of yl1 was controlled by recessive nuclear gene.By employing the MutMap method,the mutation responsible for the phenotype was mapped to a 6.17 Mb region between 17.34 and 23.51 Mb on chromosome 3.Two non-synonymous single-nucleotide polymorphisms(SNPs)located in the gene locus LOC_Os03g31210 and LOC_Os03g36760 were detected in this region.The two SNPs were further confirmed by PCR and Sanger sequencing.The expression patterns of the two candidate genes indicated that LOC_Os03g36760 showed greater potential for functional verification.Subcellular protein localization revealed that the encoded product of LOC_Os03g36760 was localized in the nucleus,cytoplasm,and plasma membrane.These results will be useful for further characterization and cloning of the yl1 gene,and for research on the molecular mechanisms controlling biogenesis and chloroplast biochemical processes.

Synergistic combination of a Co-doped𝜎σ-MnO_(2)cathode with an electrolyte additive for a high-performance aqueous zinc-ion battery

The key challenges in aqueous zinc-manganese dioxide batteries(MnO_(2)//Zn)are their poor electrochemical kinetics and stability,which are mainly due to low conductivity and the inevitable dissolution of MnO_(2).A syn-ergistic combination of a Co-doped𝜎σ-MnO_(2)electrode(Co-MnO_(2))and a Co(CH_(3)COO)_(2)•4H_(2)O(CoAc)electrolyte additive is here developed to design a high-performance aqueous MnO_(2)//Zn battery(denoted as a Co-MnO_(2)//Zn battery with CoAc).The introduction of Co ions(Co^(3+)/Co^(2+))into the𝜎σ-MnO_(2)electrode is achieved via a facile one-step electrodeposition method.Benefitting from the synergistic coupling effect of the Co-MnO_(2)electrode and the CoAc electrolyte additive,the fabricated Co-MnO_(2)//Zn battery with CoAc shows a commendable dis-charge capacity of 313.8 mAh g^(−1)at 0.5 A g^(−1),excellent rate performance,excellent durability over 1000 cycles(∼92%capacity retention at 1.0 A g^(−1))and admirable energy density(439.3 Wh kg^(−1)),which is a significant improvement compared with an un-doped𝜎σ-MnO_(2)//Zn battery.

Genome-wide analysis and molecular dissection of the SPL gene family in Salvia miltiorrhiza

SQUAMOSA promoter binding protein-likes （SPLs） are plant-specific transcription factors playing vital regulatory roles in plant growth and development. There is no information about SPLs in Salvia miltiorrhiza （Danshen）, a significant medicinal plant widely used in Traditional Chinese medicine （TCM） for＆gt;1,700 years and an emerging model plant for TCM studies. Through genome-wide identification and subsequent molecular cloning, we identified a total 15 SmSPLs with divergent sequence features, gene structures, and motifs. Comparative analysis showed sequence conservation between SmSPLs and their Arabidopsis counterparts. A phylogenetic tree clusters SmSPLs into six groups. Many of the motifs identified commonly exist in a group/subgroup, implying their functional redundancy. Eight SmSPLs were predicted and experimental y validated to be targets of miR156/157. SmSPLs were differen-tial y expressed in various tissues of S. milltiorrhiza. The expression of miR156/157-targeted SmSPLs was increased with＆amp;nbsp;the maturation of S. miltiorrhiza, whereas the expression of miR156/157 was decreased, confirming the regulatory roles of miR156/157 in SmSPLs and suggesting the functions of SmSPLs in S. miltiorrhiza development. The expression of miR156/157 was negatively correlated with miR172 during the maturation of S. miltiorrhiza. The results indicate the significance and complexity of SmSPL-, miR156-, and miR172-mediated regula-tion of developmental timing in S. miltiorrhiza.

Fabrication of room temperature continuous-wave operation GaN-based ultraviolet laser diodes

Two kinds of continuous-wave GaN-based ultraviolet laser diodes（LDs） operated at room temperature and with different emission wavelengths are demonstrated.The LDs epitaxial layers are grown on GaN substrate by metalorganic chemical vapor deposition,with a 10 × 600 μm^2 ridge waveguide structure.The electrical and optical characteristics of the ultraviolet LDs are investigated under direct-current injection at room temperature.The stimulated emission peak wavelength of first LD is 392.9 nm,the threshold current density and voltage is 1.5kA/cm^2 and 5.0 V,respectively.The output light power is 80 mW under the 4.0 kA/cm^2 injection current density.The stimulated emission peak wavelength of second LD is 381.9 nm,the threshold current density the voltage is2.8 kA/cm^2 and 5.5 V,respectively.The output light power is 14 mW under a 4.0 kA/cm^2 injection current density.

Plasma-inducedε-MnO_(2)based aqueous zinc-ion batteries and their dissolution-deposition mechanism

MnO_(2)has attracted great interest in working as the cathode of zinc ion batteries.However,the development of high-capacity,high-energy-density,and durable manganese-based cathodes with an easy synthesis strategy and proper energy storage mechanism remains an ongoing challenge.Herein,a facile plasmainduced strategy was demonstrated to introduce oxygen vacancies into theε-MnO_(2),and the obtained oxygen vacancies-richε-MnO_(2)nanosheets(ε-MnO_(2-x))show satisfactory electrochemical performances.Furthermore,an appropriate energy storage mechanism for dissolution/deposition was proposed.Thanks to a synergistic effect of the oxygen vacancies inε-MnO_(2)nanosheets and the exposed free-standing collector for Mn^(2+) dissolution/deposition,theε-MnO_(2-x) nanosheets electrode delivers a remarkable capacity(337 mAh g^(-1)at 0.1 A g^(-1))and exhibits an ultrahigh energy density of 462 Wh kg^(-1)(based on the weights of the cathode active material).Furthermore,impressive durability with 85.9%capacity retention after 1000 cycles was obtained.The superior electrochemical performance makes the plasma-induced strategy promising for designing advanced metal oxide electrode materials for high-performance aqueous zinc ion batteries.

Analysis of the growth of GaN epitaxy on silicon

Due to the great potential of Ga N based devices, the analysis of the growth of crack-free Ga N with high quality has always been a research hotspot. In this paper, two methods for improving the property of the Ga N epitaxial layer on Si（111） substrate are researched. Sample A, as a reference, only has an Al N buffer between the Si substrate and the epitaxy. In the following two samples, a Ga N transition layer（sample B） and an Al Ga N buffer（sample C） are grown on the Al N buffer separately. Both methods improve the quality of Ga N. Meanwhile, using the second method, the residual tensile thermal stress decreases. To further study the impact of the two introduced layers, we investigate the stress condition of Ga N epitaxial layer by Raman spectrum. According to the Raman spectrum, the calculated residual stress in the Ga N epitaxial layer is approximately 0.72 GPa for sample B and0.42 GPa for sample C. The photoluminescence property of Ga N epitaxy is also investigated by room temperature PL spectrum.

Fast Multipole Accelerated Boundary Integral Equation Method for Evaluating the Stress Field Associated with Dislocations in a Finite Medium

In this paper,we develop an efficient numericalmethod based on the boundary integral equation formulation and new version of fast multipole method to solve the boundary value problem for the stress field associated with dislocations in a finite medium.Numerical examples are presented to examine the influence from material boundaries on dislocations.