The Preparation and Catalytic Performance of Nanoporous CuO/CeO₂Composites

Nanoporous CuO/CeO2 ribbons are successfully prepared through dealloying melt-spun Al80-xCu20Cex (x = 0.5, 1, 2, 3, at%) alloy in a 5 wt% NaOH aqueous solution, followed by calcining in air. The samples are characterized by XRD, SEM, EDS, HRTEM, Raman and gas chromatograph. For the dealloyed melt-spun Al80-xCu20Cex (x = 0.5, 1, 2, 3, at%) alloy, the XRD results indicate that Cu and Cu2O are formed, while CuO and CeO2 are formed coupled with calcinations. The SEM shows that the CuO/CeO2 ribbons with a homogeneous pore/grain structure are thermally stable up to 600℃because uniform CeO2 particles are dispersedly loaded on the fine CuO grains of the porous structure, which is validated by TEM again. Meanwhile, the Raman spectra show that the concentration of oxygen vacancies reach a maximum value when the calcining temperature at 600℃. In addition, the gas chromatograph results show that the dealloyed Al78Cu20Ce2 ribbons with calcined at 600℃have the best active catalysis for CO oxidation and the rates of CO conversation reaching at 50% and 100% are 150℃and 320℃, respectively, owing to the synergetic effects of the CuO and CeO2 species.

Single-cell transcriptome sequencing reveals the mechanism regulating rice plumule development

Seed plumules comprise multiple developing tissues and are key sites for above-ground plant organ morphogenesis.Here,the spatial expression of genes in developing rice seed plumules was characterized by single-cell transcriptome sequencing in Zhongjiazao 17,a popular Chinese indica rice cultivar.Of 15 cell clusters,13 were assigned to cell types using marker genes and cluster-specific genes.Marker genes of multiple cell types were expressed in several clusters,suggesting a complex developmental system.Some genes for signaling by phytohormones such as abscisic acid were highly expressed in specific clusters.Various cis-elements in the promoters of genes specifically expressed in cell clusters were calculated,and some key hormone-related motifs were frequent in certain clusters.Spatial expression patterns of genes involved in rapid seed germination,seedling growth,and development were identified.These findings enhanced our understanding of cellular diversity and specialization within plumules of rice,a monocotyledonous model crop.

全国产氦液化器的性能调控优化研究及其工程化应用

超导磁体一般工作在液氦温区(–269℃),需要稳定可靠的冷源为其提供保障.为满足未来高能量粒子对撞机所需高场强超导二极磁体研究的测试需求,本文针对自主研制的国内首台全国产氦液化器开展了性能调控优化研究,分别实现了冷箱和液氦杜瓦降温过程的优化控制,节省压缩机功耗分别为12.3%和25.2%,显著提高了氦液化器的经济性.在此基础上,针对用户现场不同运行工况,实现了氦液化器适应变负荷的自动控制调节功能.分析了氦液化器在各负荷状态下的运行能耗;在不考虑液氮消耗的前提下,氦液化器最低能耗为2.4 kW h/L.通过调控优化及实验测试,成功实现了氦液化器与用户端磁体测试平台的联合运行,并通过了全国产氦液化器的长时间运行可靠性测试,满足了磁体测试系统对其低温制冷系统在稳定性和可靠性方面的要求.目前,该氦液化器已累计稳定运行超过两个月,生产液氦超过35000 L,推动首台国产化加速器高场强超导二极磁体取得了12.47 T磁场强度新指标的突破.这是全国产氦液化器首次应用于超导二极磁体测试平台,该工程应用未来可进行进一步推广.

Transplantation of UC-MSCs on collagen scaffold activates follicles in dormant ovaries of POF patients with long history of infertility

Premature ovarian failure(POF) is a refractory disease for clinical treatment with the goal of restoring fertility. In this study,umbilical cord mesenchymal stem cells on a collagen scaffold(collagen/UC-MSCs) can activate primordial follicles in vitro via phosphorylation of FOXO3 a and FOXO1. Transplantation of collagen/UC-MSCs to the ovaries of POF patients rescued overall ovarian function, evidenced by elevated estradiol concentrations, improved follicular development, and increased number of antral follicles. Successful clinical pregnancy was achieved in women with POF after transplantation of collagen/UC-MSCs or UC-MSCs. In summary, collagen/UC-MSC transplantation may provide an effective treatment for POF.

Synthesis of magnetic polyphosphazene-Ag composite particles as surface enhanced Raman spectroscopy substrates for the detection of melamine

Magnetic polyphosphazene(MPZS) particles coated by Ag nanoparticles(MPZS-Ag) have been developed as surface enhanced Raman spectroscopy(SERS) substrates for sensitive detection of melamine in aqueous solutions and milk samples.5,5’-Dithiobis-(2-nitrobenzoic acid)(DTNB) was used as model analyte to test the SERS activity of the MPZS-Ag particles.The prepared MPZS-Ag particles possess both magnetic responsiveness and excellent SERS properties.SERS detection of different concentrations of melamine aqueous solutions and spiked milk samples were performed by the MPZS-Ag particles.The limit of detection(LOD) of the melamine in aqueous solutions was 10^-7 mol/L(0.0126 mg/L) and 0.6 mg/L in real milk samples using the MPZS-Ag particles as SERS substrates.The LOD of the melamine are much lower than the safety values of Food and Drug Administration and Codex Alimentarius Commission.These results indicate that the MPZS-Ag particles have promising application prospect for SERS analysis in food safety fields.

OPAQUE3, encoding a transmembrane bZIP transcription factor, regulates endosperm storage protein and starch biosynthesis in rice

Starch and storage proteins are the main components of rice(Oryza sativa L.)grains.Despite their importance,the molecular regulatory mechanisms of storage protein and starch biosynthesis remain largely elusive.Here,we identified a rice opaque endosperm mutant,opaque3(o3),that overaccumulates 57-kDa proglutelins and has significantly lower protein and starch contents than the wild type.The o3 mutant also has abnormal protein body structures and compound starch grains in its endosperm cells.OPAQUE3(O3)encodes a transmembrane basic leucine zipper(bZIP)transcription factor(OsbZIP60)and is localized in the endoplasmic reticulum(ER)and the nucleus,but it is localized mostly in the nucleus under ER stress.We demonstrated that O3 could activate the expression of several starch synthesis-related genes(GBSSI,AGPL2,SBEI,and ISA2)and storage protein synthesis-related genes(OsGluA2,Prol14,and Glb1).O3 also plays an important role in protein processing and export in the ER by directly binding to the promoters and activating the expression of OsBIP1 and PDIL1-1,two major chaperones that assist with folding of immature secretory proteins in the ER of rice endosperm cells.High-temperature conditions aggravate ER stress and result in more abnormal grain development in o3 mutants.We also revealed that OsbZIP50 can assist O3 in response to ER stress,especially under high-temperature conditions.We thus demonstrate that O3 plays a central role in rice grain development by participating simultaneously in the regulation of storage protein and starch biosynthesis and the maintenance of ER homeostasis in endosperm cells.

Improved electron capture capability of field-assisted exponential-doping GaN nanowire array photocathode

The exponential-doping GaN nanowire arrays(GaN NWAs)photocathode has a"light-trapping effect",and the built-in electric field can promote the concentration of the photogene rated carrier center to the top surface of the nanowire.However,in the preparation ofactual NWAs photocathodes,the problem that photons emitted from the sides of the nanowires cannot be effectively collected has been encountered.Our proposed field-assisted exponential-doping GaN NWAs can bend the motion trajectory of the emitted electrons toward the collecting side.In this study,the quantum efficiency(QE)and collection efficiency(CE)of the external field-assisted exponential-doping GaN NWAs photocathode are derived based on the two-dimensional carrier diffusion equation and the initial energy and angular distribution,respectively.For a field-assisted exponential-doping GaN NWAs with a width d=200 nm and a height H=400 nm,the optimal structural parameters are obtained:the incident angleθ=50°and the nanowire spacing is L=335.6 nm.On this basis,the field intensity of 0.5 V/μm can maximize the CE of the NWAs.All the results show that the field-assisted approach does contribute to the collection of emitted electrons,which can provide theoretical guidance for high-performance electron sources based on exponential-doping GaN NWAs photocathodes.And field-assisted exponential-doping GaN NWAs cathode is expected to be verified by the experimental results in the future.

High-efficient electron collection capability of graded Al compositional GaN nanowire arrays cathode

Based on the purpose of solving the"secondary absorption"of adjacent nanowires and the lateral emission in the Ga N nanowire arrays(NWAs)cathode,an exponential-doping and graded Al compositional Ga N NWAs photocathode is proposed,which could generate internal electric field to increase the quantum efficiency(QE)of top surface,and the introduction of an external electric field promote the side-emission electrons to shift toward the collecting side.The QE and collection efficiency(CE)of exponential-doping and graded compositional Ga N NWAs under different array structure parameters,incident angles and external electric field intensities are analyzed.The results show that although the collection ratio of emitted electrons in the exponential-doping Ga N NWAs is higher,the graded Al compositional photocathode with a stronger built-in electric field can obtain better CE under the application of an external electric field,and the peak value can reach 33.2%in a specific structure.External electric field has a more significant effect on the CE of uniform-doping Ga N NWAs.The solutions provided in this study can make the Ga N NWAs photocathode more suitable for the strict requirements of vacuum electron sources.