The Clumpy Structure of Five Star-bursting Dwarf Galaxies in the MaNGA Survey

The star-forming clumps in star-bursting dwarf galaxies provide valuable insights into understanding the evolution of dwarf galaxies.In this paper,we focus on five star-bursting dwarf galaxies featuring off-centered clumps in the Mapping Nearby Galaxies at Apache Point Observatory survey.Using the stellar population synthesis software Fitting Analysis using Differential evolution Optimization,we obtain the spatially resolved distribution of the star formation history,which allows us to construct the g-band images of the five galaxies at different ages.These images can help us to probe the evolution of the morphological structures of these galaxies.While images of a stellar population older than 1 Gyr are typically smooth,images of a stellar population younger than 1 Gyr reveal significant clumps,including multiple clumps which appear at different locations and even different ages.To study the evolutionary connections of these five galaxies to other dwarf galaxies before their star-forming clumps appear,we construct the images of the stellar populations older than three age nodes,and define them to be the images of the"host"galaxies.We find that the properties such as the central surface brightness and the effective radii of the hosts of the five galaxies are in between those of dwarf ellipticals(dEs)and dwarf irregulars(dIrrs),with two clearly more similar to dEs and one more similar to dIrrs.Among the five galaxies,8257-3704 is particularly interesting,as it shows a previous starburst event that is not quite visible from its gri image,but only visible from images of the stellar population at a few hundred million years.The star-forming clump associated with this event may have appeared at around 600 Myr ago and disappeared at around 40 Myr ago.

Haploids can be induced in knockout mutants of OsPLA1,but not OsDMP3 or OsDMP6,in rice

Doubled haploid(DH)technology is an important tool in crop breeding because it can significantly accelerate the breeding process.ZmPLA1/MATL/NLD and ZmDMP are two key genes controlling haploid induction(HI)in maize,exhibiting a synergistic effect.However,it is unknown whether knock out of ZmDMP orthologs can stimulate HI in rice.In this study,a ZmPLA1 ortholog(OsPLA1)and two ZmDMP orthologs(OsDMP3 and OsDMP6)were identified in rice.All three genes encode plasma membrane-localized proteins and were highly expressed in mature anthers.Knockout of OsPLA1 in both Minghui 63 and Nipponbare resulted in reduced seed setting rate(SSR)and caused HI.The osdmp3,osdmp6 and the double mutant failed to trigger HI independently,nor increased the haploid induction rate(HIR)when combined with ospla1.Repeated pollinations operations of QX654A with the ospla1 mutant significantly improve SSR,while reducing HIR.RNA-seq profiling of mature ospla1 mutant anthers indicated that a large number of differentially expressed genes(DEGs)were enriched in redox homeostasis and lipid metabolic GO terms,plant hormone signal transduction,and MAPK signaling pathways.These findings provide important insights towards construction of an efficient DH breeding technology and study of the molecular mechanism of HI in rice.

策划与互动之争:语体特征对文娱直播效果的影响研究

新技术的出现及其与特定语境的结合会催生新的媒介语体,直播语体正是在直播技术赋能下产生的。笔者与团队成员在阿里巴巴旗下的来疯直播平台进行了为期7个月的参与式观察,并对从业者进行了深度访谈。研究发现直播语体具有互动和策划两种特征,且这两种特征的语体对直播效果的影响各有千秋。基于此,研究团队用A/B实验法探究了两种特征对直播效果的影响。结果表明,在提高10s短时停留率方面,互动特征的直播语体更有优势,在人均观看时长方面则相反。此外,本研究还基于离散性指标分析了不同语体特征下效果的稳定性。策划语体能带来更长的用户观看时间,更好地建立持久关系;而互动语体在吸引用户短暂停留和增加用户互动方面具有优势。

Development of high-oil maize haploid inducer with a novel phenotyping strategy

Doubled haploid(DH) technology is important in modern maize breeding. Haploid inducers determine the efficiency of both haploid induction and identification. It has taken decades to improve the efficiency,haploid induction rate(HIR), from the ~2% of the ancestor haploid inducer, stock6, to the ~10% of modern haploid inducers. Improvement of kernel oil content(KOC) would further enhance haploid identification efficiency. Using molecular marker-assisted selection, in combine with the number of haploids per ear as phenotypic criterion, we developed a new high-oil haploid inducer line, CHOI4, with a mean HIR of 15.8%and mean KOC of 11%. High KOC of CHOI4 can achieve a mean accuracy greater than 90% in identification of haploids of different backgrounds, with reduced false discovery rates and false negative rates in comparison with the previous high-oil haploid inducer line, CHOI3. Comparison of phenotypic selection strategies suggested that the number of haploids per ear can be used as a phenotyping criterion during haploid inducer line development. CHOI4 could further increase the efficiency of large-scale DH breeding programs with lower cost.

Effect of Ball Milling Time on Microstructure and Hydrogen Storage Properties of Nd_(5)Mg_(41)Ni Alloy

Mg-based alloys must be dehydrogenated at high pressure and temperatures, limiting their practical application. In this paper, Nd_(5)Mg_(41)Ni alloy was prepared by vacuum melting, and the as-cast alloy was ball milled for 5 h, 10 h, 15 h, and 20 h. The effect of ball milling time on the microstructure and hydrogen storage properties of the alloy was systematically studied. The alloy comprises Nd_(5)Mg_(41), NdMg_(12), NdMg_(3), and Mg_(2)Ni phases. The Nd_(5)Mg_(41)Ni alloy milling for 10 h can reach 95% of the saturated hydrogen absorption at 553 K by 40 s, and the alloy can desorb hydrogen only by 20 min. The dehydrogenation activation energy is only 99.9 kJ/mol H_(2). Ball milling makes the alloy produce many nanocrystalline and amorphous structures. The nano-grain boundary provides a channel for the diffusion of hydrogen atoms, and the high energy at the grain boundary provides energy for the phase deformation nucleus. Ball milling leads to the refinement of alloy particles and shortens the diffusion distance of hydrogen atoms to the interior of alloy particles. Defects such as twins and dislocations generated by milling provide energy for the phase deformation nucleus during the hydrogen absorption and desorption.

Establishment of an efficient haploid identification system by engineering anthocyanin accumulation in the wheat embryo

Dear Editor,Bread wheat(Triticum aestivum)is one of the most important food crops and provides approximately 20%of the food calories for human consumption.A 70%increase in wheat production is needed by 2050 to keep pace with the growing global population(International Wheat Genome Sequencing,2014).Developing superior cultivars is an efficient way to improve yield.Nevertheless,conventional breeding is time consuming,as more than eight generations are needed to develop new plant varieties.Using doubled haploid(DH)technology,homozygous lines can be produced in only two generations,dramatically accelerating the breeding process.In wheat,haploids can be obtained by cross pollination with corn pollen followed by embryo rescue(Laurie and Bennett,1988).In maize,haploids can be induced by haploid inducer lines derived from Stock6(Liu et al.,2022).The cloning of two genes that control haploid induction(HI)in maize,MATL/ZmPLA1/NLD and ZmDMP,paved the way for DH breeding in more crop species(Jacquier et al.,2020).Further studies have shown that loss of function of TaPLAs triggers wheat HI with an efficiency of 5.88%to 31.6%(Liu et al.,2020a,2020b);this would be a promising approach for establishing a new,simple,and more efficient DH breeding method in wheat.

Mitigation of tribocorrosion of metals in aqueous solutions by potential-enhanced adsorption of surfactants

Corrosion and corrosive wear occur commonly on metals surface in aqueous solutions.External electric field is usually considered as one of the factors to accelerate corrosion or corrosive wear of materials in the presence of conventional electrolytes.This work aims to reposition widely believed perspective by experimental justification which have been conducted in aqueous solutions containing surfactants.Electric potential of metal surfaces was modulated externally within the electrochemical potential window of the metal electrode-solution-counter electrode system,which actively regulated the adsorption or desorption of surfactant molecule in the aqueous solution over the electrodes to form a molecular barrier of electron transportation across the electrode–electrolyte interface.The advantage of the approach over the anodic passivation is negligible redox reactions on the protected electrode surface while a better lubricious and wear resistant film than oxide is maintained in the meantime.Tribopairs of several metal/metal and metal/ceramic were tested by employing a ball-on-disc tribometer with anionic and cationic surfactants solutions.For anionic surfactant as the modifier,positive surface potential enables coefficient of friction to be decreased by promoting the formation of adsorption film on metal surface in aqueous solutions.For cationic surfactant,negative surface potential plays a role in decreasing the coefficient of friction.Phase diagrams of friction and wear in wide ranges of surfactant concentration and surface potential were plotted for the tested metal/metal and metal/ceramic tribopairs.These results indicate that the adsorption behavior of molecules or ions at the metal–aqueous interface can be well regulated when an external electric field is present without inducing corrosion or corrosive wear.

Organic Passivation of Deep Defects in Cu(In,Ga)Se_(2) Film for Geometry-Simplified Compound Solar Cells

Diverse defects in copper indium gallium diselenide solar cells cause nonradiative recombination losses and impair device performance.Here,an organic passivation scheme for surface and grain boundary defects is reported,which employs an organic passivation agent to infiltrate the copper indium gallium diselenide thin films.A transparent conductive passivating(TCP)film is then developed by incorporating metal nanowires into the organic polymer and used in solar cells.The TCP films have a transmittance of more than 90%in the visible and nearinfrared spectra and a sheet resistance of~10.5Ω/sq.This leads to improvements in the open-circuit voltage and the efficiency of the organic passivated solar cells compared with control cells and paves the way for novel approaches to copper indium gallium diselenide defect passivation and possibly other compound solar cells.

High-throughput haploid induction in species with bisexual flowers

Dear Editor,Doubled haploid(DH)technology can significantly accelerate the development of homozygous lines.DH breeding has achieved great success inmaize because of the discovery of the first haploid inducer,Stock6,and the development of a series of high-efficiency haploid inducers(Hu et al.,2016).Pioneering studies on the genetic basis of haploid induction(HI)revealed that loss-offunction mutation of the phospholipase gene ZmPLA1/MATL/NLD triggers HI and that the HI rate(HIR)can be dramatically enhanced by a single nucleotide substitution from T to C in ZmDMP(Jacquier et al.,2020).Remarkably,knockout of ZmPLA1/MATL/NLD homologs in rice,wheat,and foxtail millet results in HIRs of 2%–6%,5%–15%,and 2%–3%,respectively(Jacquier et al.,2020;Cheng et al.,2021).In addition,loss of function of ZmDMP-like genes enables HI in species including Arabidopsis,tomato,rapeseed,tobacco,etc.,with an average HIR of around 2%(Zhong et al.,2020,2022a,2022b).These successes have laid solid foundations for the construction of a universal DH breeding system in different crop species.More importantly,HI-Edit/IMGE systems that enable gene editing in elite germplasms have been established on the basis of HI,making HI even more important(Kelliher et al.,2019;Wang et al.,2019).

粉煤灰基土壤调理剂作用下盐碱土壤微观结构变化规律

以宁夏银北地区典型盐碱土壤为研究对象,采用X射线衍射(XRD)、红外光谱(FTIR)、比表面全自动物理吸附仪(BET)以及扫描电子显微镜(SEM)等测试技术对粉煤灰基土壤调理剂作用下盐碱土壤颗粒微观结构进行研究和系统表征。结果表明,利用调理剂改良后土壤矿物的主要成分未发生改变,但是添加调理剂后土壤有新晶相方解石生成;土壤的pH值大幅降低,由9.01降低到7.66;土壤红外吸收变化较小,Si-O-Si和有机质吸收峰略有增强;随着调理剂的增加,土壤小颗粒开始团聚,孔隙率逐渐增加,以添加2.5wt%组为例,15天后样品孔隙率达到21.30%,30天后样品孔隙率达到25.29%,约为未添加调理剂组的两倍;土壤颗粒的比表面积略有增加,30天后由初始的23.06 m;/g增加到25.55 m;/g。

Establishment of a dmp based maternal haploid induction system for polyploid Brassica napus and Nicotiana tabacum

Doubled haploid(DH) technology is used to obtain homozygous lines in a single generation, a technique that significantly accelerates the crop breeding trajectory. Traditionally, in vitro culture is used to generate DHs, but this technique is limited by species and genotype recalcitrance. In vivo haploid induction(HI) through seed is widely and efficiently used in maize and was recently extended to several other crops. Here we show that in vivo HI can be triggered by mutation of DMP maternal haploid inducer genes in allopolyploid(allotetraploid) Brassica napus and Nicotiana tabacum. We developed a pipeline for selection of DMP orthologs for clustered regularly interspaced palindromic repeats mutagenesis and demonstrated average amphihaploid induction rates of2.4% and 1.2% in multiple B. napus and N. tabacum genotypes, respectively. These results further confirmed the HI ability of DMP gene in polyploid dicot crops. The DMP-HI system offers a novel DH technology to facilitate breeding in these crops. The success of this approach and the conservation of DMP genes in dicots suggest the broad applicability of this technique in other dicot crops.

Construction of homozygous diploid potato through maternal haploid induction

Reinventing the tetraploid potato into a seed-propagated,diploid,hybrid potato would significantly accelerate potato breeding.In this regard,the development of highly homozygous inbred lines is a prerequisite for breeding hybrid potatoes,but self-incompatibility and inbreeding depression present challenges for developing pure inbred lines.To resolve this impediment,we developed a doubled haploid(DH)technology,based on mutagenesis of the potato DOMAIN OF UNKNOWN FUNCTION 679 membrane protein(StDMP)gene.Here,we show that a deficiency in StDMP allows the generation of maternal haploids for generating diploid potato lines.An exercisable protocol,involving hybridization,fluorescent marker screening,molecular and flow cytometric identification,and doubling with colchicine generates nearly 100%homozygous diploid potato lines.This dmp-triggered haploid induction(HI)system greatly shortens the breeding process and offers a robust method for generating diploid potato inbred lines with high purity.

手性催化与合成中的一些凝聚态化学问题

凝聚态化学作为一门研究化学反应中凝聚态物质的科学,最近引起了化学界的广泛关注。从手性化学角度出发,本文列举了近年来手性催化与合成中的一些凝聚态化学现象,分类介绍了不对称催化反应中不同类型的凝聚态物质,并通过列举实例分析讨论了凝聚态物质的具体组成、层次结构等因素对反应的催化活性、对映及区域选择性控制影响,以望能引起业界对凝聚态科学的关注,启发更多学者从凝聚态化学角度思考有机化学反应本质并解决相关问题,完善凝聚态科学体系。

A 4-bp Insertion at ZmPLA 1 Encoding a Putative Phospholipase A Generates Haploid Induction in Maize

Maize is one of the most important crops in the world and is also an essential raw material for the food, fuel, and fodder industries. Maize hybrids are widely used today, and gain of elite inbred lines is a crucial step for hybrid breeding.

Genome Editing and Double-Fluorescence Proteins Enable Robust Maternal Haploid Induction and Identification in Maize

Dear Editor Genome editing technologies have paved the way for exciting and novel applications in plant biotechnology. Doubled haploid （DH） technology has a significant and valuable advantage over traditional approaches in crop breeding. Unlike traditional breeding processes, which may take over eight generations to stabilize the genetic background of interest.