基于范畴论的粒合成形式化方法

针对粒计算中细粒层到粗粒层的转换问题,提出一种基于范畴论的粒合成形式化方法。以粒结构为对象,将粒结构映射作为态射构成粒结构范畴,利用范畴论的外推实现粒结构合并,并给出相应的粒合成算法GrSA,结合具体案例说明该方法解决粒合成问题的过程。应用结果表明,该方法能够实现粒层之间的转换。

田间估计马铃薯反义RNA调节抑制复合淀粉粒合成酶GBSS基因的表达

在淀粉粒中，复合淀粉粒合成酶（GBSS）催化直链淀粉的合成。对大量离体培养、温室生长和田间生长的基因转移的马铃薯块茎，分析了反义RNA调节抑制GBSS基因的表达作用，并指出在某一无性系中GBSS基因表达的稳定和完全的抑制作用。同时发现了其它三个基因转移的基因型，有不完全的和不稳定的抑制作用，它们与非转化控制基因型相比较，GBSS的活性直链淀粉的含量明显下降。又观察到GBSS基因表达的抑制水平与产量及干物质重量二者之间无关。

小麦淀粉粒束缚淀粉合成酶基因多态性的分子鉴定

运用 6 %的SDS PAGE对 14个小麦品种成熟籽粒Wx蛋白的多态性进行了鉴定 ,结果表明 ,14个小麦品种根据其Wx蛋白的缺失情况可分为 6种组合类型。另外 ,根据Wx A1、Wx B1和Wx D1这 3个位点基因序列和变异情况分别设计了PCR引物 ,扩增结果表明 :Wx A1位点突变材料扩增产物为 32 7bp ,正常材料中扩增不到该特异带 ;在Wx B1位点扩增出 187bp目标带 ,突变材料没有该扩增产物 ;在Wx D1位点扩增出约 70 0bp目标带 ,突变材料没有该特异带。与前人的研究结果相比 ,Wx B1引物在 3个位点的扩增产物长度更短 ,差异更大 ,在 2 %琼脂糖胶上即可清楚分开 ,缩短了鉴定时间 ,提高了效率 。

氮钾对杂交水稻B优827籽粒淀粉含量及淀粉合成酶活性的影响

以优质杂交籼稻B优827为材料,通过施用不同水平的氮、钾肥,并在B优827灌浆时段测定籽粒的直链淀粉、总淀粉含量以及淀粉合成酶的活性,分析氮、钾对水稻灌浆过程中籽粒淀粉积累、淀粉合成关键酶活性的影响,以及直链淀粉的积累与淀粉合成关键酶活性间的相关性。B优827的直链淀粉含量在开花后20d内呈线性增加,开花20d后有所下降;可溶性淀粉合成酶活性变化呈单峰曲线,开花后12d酶活性达到了最高值,以后随天数增加而迅速降低;淀粉粒结合型淀粉合成酶活性变化呈单峰曲线,开花后15d酶活性达到最高值,开花后15d籽粒直链淀粉含量也接近最高值;灌浆中后期可溶性淀粉合成酶(SSS)、淀粉粒结合型淀粉合成酶(GBSS)与直链淀粉含量呈现出显著的正相关关系。增施氮肥可以提高SSS和GBSS活性,施钾肥在生育前期提高SSS和GBSS活性,后期抑制两者的活性;氮肥和钾肥均有促进淀粉积累的作用,但氮肥施用量过高时会抑制淀粉的积累。适当控施氮肥、增施钾肥是提高B优827籽粒产量的有效途径。

黄芪毛状根淀粉粒结合淀粉合成酶(GBSS)基因表达载体的构建及在大肠杆菌中的表达

以膜荚黄芪毛状根中克隆得到的GBSS基因序列设计一对特殊引物 ,得到了包含GBSS基因全部表达序列的1.9kb的cDNA片段。该片段正向连接于切除了GUS基因的pBI12 1上 ,构建成表达载体pBI-gbss。SDS -PAGE实验证实了GBSS基因在含有该表达载体的DH5α的大肠杆菌中得到表达。酶活性测定表明转化菌株比未转化菌株高出 2 0 %。

基因编辑递送系统:将“手术刀”送进突变细胞

随着第三代基因编辑技术——CRISPR/Cas9技术斩获2020年诺贝尔化学奖,“基因编辑”一词便频繁地出现在大众视野中。然而,这把基因的“手术刀”只有被送到靶细胞才能发挥其特定作用,因此,在体内精准递送基因编辑系统仍然是该技术应用于医药学领域的重大挑战之一。

大尺寸硅片自旋转磨削运动分析及仿真

本文利用数学矩阵方法,建立大尺寸硅片自旋转磨削运动的理论模型,研究了砂轮半径、硅片和砂轮旋转速度、旋转方向等因素的选择及各因素对磨削轨迹的影响,同时还研究了磨粒合成运动速度的变化规律。研究结果表明,随着砂轮半径的增大,磨削轨迹的曲率减小,选用较小直径砂轮将更有利硅片表面质量的提高。当转速比i大于零,随着i值的增大,磨削轨迹的曲率逐渐减小。在转速比i小于零的情形,当转速比i=-2时,磨削轨迹曲率为0,磨削轨迹的形状接近一条直线。磨粒合成运动速度随砂轮转速和硅片转速的增大而增大。

大田遮荫对紫心甘薯块根中酶活性的影响

在大田条件下,采用人工遮荫的方法探讨光照不足导致紫心甘薯块根品质下降的酶学机制。研究结果表明:在遮荫条件下,2个甘薯品种济薯18和Ayamurasaki叶片RUBPCase活性显著降低;叶片和块根中ATPase活性下降;块根ADPGPPase和UDPGPPase活性均显著降低,降低幅度随胁迫强度而增加;遮荫对块根可溶性淀粉合成酶(soluble starch synthase,SSS)和淀粉粒结合态淀粉合成酶(granulebound starch synthase,GBSS)活性的影响存在品种间差异,济薯18块根SSS活性显著降低,GBSS活性则不同程度高于对照,而Ayamurasaki的SSS活性却高于对照,GBSS活性则随遮光胁迫强度而降低;遮荫对花青素合成的关键酶苯丙氨酸解氨酶(Phenglalanine Ammonia Lyase,PAL)活性影响则很小。因此,遮荫胁迫从源库流各环节影响了紫心甘薯品质合成相关酶,其中RUBPCase、ATPase、ADPGPPase和UDPGPPase活性显著降低是导致紫心甘薯块根品质下降的主要原因。

Synthesis,characterization and gas-sensing properties of Pd-doped SnO_2 nano particles

SnO2 nano particles with various Pd-doping concentrations were prepared using a template-free hydrothermal method.The effects of Pd doping on the crystal structure,morphology,microstructure,thermal stability and surface chemistry of these nano particles were characterized by transmission electron microscope,X-ray diffractometer and X-ray photoelectron spectroscope respectively.It was observed that Pd-doping had little effect on the grain sizes of the obtained SnO2 nano particles during the hydrothermal route.During thermal annealing,Pd-doping could restrain the growth of grain sizes below 500℃ while the grain growth was promoted when the temperature increased to above 700℃.XPS results revealed that Pd existed in three chemical states in the as-synthesized sample as Pd^0,Pd^2＋ and Pd^4＋,respectively.Pd^4＋ was the main state which was responsible for improving the gas-sensing property.The optimal Pd-doping concentration for better gas-sensing property and thermal stability was 2.0%-2.5% （mole fraction）.

Discrete element and finite element coupling simulation and experiment of hot granule medium pressure forming

The granule medium of discreteness is supposed to be continuous（Drucker-Prager model） in the existing finite element simulation analysis on the hot granule medium pressure forming（HGMF） process, so the granule medium may produce tensile stress in the process of pressure-transferring and flowing, which does not coincide with the reality. The analysis method, discrete element and finite element（DE-FE） coupling simulation, is proposed to solve the problem. The material parameters of simulation model are obtained by the pressure-transfer performance test of granule medium and the hot uniaxial tensile test of sheet metal. The DE-FE coupling simulation platform is established by adopting Visual Basic language. The features in the process that AA7075-T6 conical parts are formed by the HGMF process are analyzed and verified by the process test. The studies show that the results of DE-FE coupling simulation coincide well with the test results, which provides a new analysis method to solve the mechanics problem in the coupling of discrete and continuum.

Molecular Cloning and Characterization of a DFR from Developing Seeds of Blue-grained Wheat in Anthocyanin Biosynthetic Pathway

Blue-grained wheat derived from the hybrid Triticum aestivum L. X Thinopyrum ponticum (Podp.) Barkworth et D. R. Dewey (Agropyron elongatum (Host) P. Beauv., 2n=70). The molecular biological mechanism of the biosynthetic pathway of blue pigments in the blue grain remains unclear yet. Dihydroflavonol 4-reductase (DFR) is one of the key enzymes controlling flavonoid synthesis in anthocyanin biosynthetic pathway, and may directly participate in the formation of blue pigment in the aleurone layer of blue-grained wheat. Here we cloned a DFR cDNA (TaDFR) from the developing seeds of blue-grained wheat, and four DFR genomic DNAs from Th. ponticum (ThpDFR.t), blue-grained wheat (TaDFR.bg), white-grained offspring of light blue-grained wheat (TaDFR.wg) and Chinese Spring (2n=42) (TaDFR.csg), respectively. TaDFR cDNA encodes a 354 amino-acids polypeptide with high identity to DFR from Hordeum vulgare L. (94%), Oryza sativa L. (83%), Zea mays L.(84%). The result of cluster analysis showed that TaDFR cDNA nucleotide sequence has 100% identity with that of TaDFR.csg. The four DFR genomic DNAs have extraordinary high homology and each has three introns. The differences of the four DFR genomic DNAs mainly exist in introns. Southern blotting analysis showed that there are at least 3-5 DFR copies in wheat, the copy numbers in different color grain wheats are not significantly different. The hybridization band patterns were the same, but different from that of Th. ponticum. DFR in blue-grained wheat belongs to a DFR superfamily. Northern blotting analysis indicated that the DFR expressed in the developing seeds of both blue- and white-grained wheat at 15 d after flowering (DAF), the mRNA levels of DFR reached the highest at 18 DAF, then declined quickly and disappeared at 33 DAF But the expression levels in blue-grained seeds were higher than that in white grain at the same seed developing stages. DFR transcripts accumulated in young leaves, and leaf sheaths of blue- and white-grained wheat and Th ponticum, but not detected in roots from different color wheats and developing seeds of Th. ponticum. Results indicated that there may exist some regulatory gene(s) which can increase the expression of DFR in the aleurone layer of blue-grained wheat, and thus resulting in the formation of blue pigments.

Seed-induced synthesis of small-crystal TS-1 using ammonia as alkali source

Small-crystal TS-1 was synthesized via a seed-induced approach using ammonia as the alkali source and tetrapropylammonium bromide as an auxiliary structure-directing agent. The TS-1 samples were characterized using X-ray diffraction, N2 adsorption-desorption, Fourier-transform infrared spectroscopy, inductively coupled plasma atomic emission spectroscopy, scanning electron microscopy, and ultraviolet-visible spectroscopy. The use of the colloidal seed reduced the crystal size, and an appropriate amount of silicalite-1 seed assisted Ti incorporation into the TS-1 framework. This method reduces the cost of TS- 1 synthesis because a significantly smaller amount of tetrapropylammonium hydroxide is used. The catalytic performance of the synthesized small-crystal TS-1 samples in cyclohexanone ammoximation was better than that of bulk TS-1 as a result of improved diffusion and a larger number of active tetrahedral Ti centers.

A review of significant factors in the synthesis of hetero-structured dumbbell-like nanoparticles

This paper reviews several important factors that influence the synthesis of dumbbell‐like nanoparticles,which can significantly enhance the catalyst activity in catalytic combustion. The dumbbell‐like nanoparticles discussed in this article refer to a hetero‐structure with two nanoparticles of different materials in contact with each other. This nanostructure can be considered as a special intermediate between individual spherical nanoparticles and a core–shell nanostructure. Therefore,the synthesis of dumbbell‐like nanoparticles is more difficult than other structures. The controllability of the synthesis process, the nanoparticle size and size distribution, and the morphology of the final products depend on many factors： the seed size and size ratio could be used to influence the controllability of epitaxial growth. The component sizes and size distribution could be varied by carefully controlling the reaction temperature and reaction time. The morphology of the dumbbell‐like nanoparticles is closely related to the solvent polarity, the precursor ratio, the lattice mismatch between the two components, and the surfactant concentration. Some related synthesis methods are also briefly introduced in each section to facilitate understanding. This summary will benefit the development of new dumbbell‐like nanoparticles with various components, which have great potential in catalytic combustion of more dysoxidizable gases.

A review of applications of poly(diallyldimethyl ammonium chloride) in polymer membrane fuel cells: From nanoparticles to support materials

Polymer membrane fuel cells represent important sustainable energy devices because their operation involves zero emissions and low temperatures and their components exhibit low toxicity. Among the various components of such cells, the electrocatalyst plays the vital role of enhancing the output power density and/or working lifetime. Over the past several decades, numerous strategies have been proposed to address the challenges of electrocatalyst activity and/or durability. Herein, we review the applications of polyelectrolytes in electrocatalysts, including the enhancement of both catalytic nanoparticles and support materials. The effects of polyelectrolytes with regard to controlling the size, composition and morphology of catalytic nanoparticles, as well as the modification of support materials were summarized. In addition, the future possibilities for the research and development of polyelectrolytes in the field of catalyst design and synthesis are discussed.

Ultrasonic-Assisted Synthesis of Monodisperse Ag Nanoparticles and Their Applications in Surface Enhanced Raman Scattering and Fluorescence Enhancement

Monodisperse Ag nanoparticles with diameters of about 3.4 nm were synthesized by a facile ultrasonic synthetic route at room temperature with the reduction of borane-tert-butylamine in the presence of oleylamine （OAm） and oleic acid （OA）. The reaction parameters of time, the molar ratios of OAm to OA were studied, and it was found that these parameters played important roles in the morphology and size of the products. Meanwhile, surface enhanced Raman spectrum （SERS） property suggested the Ag nanoparticles exhibited high SERS effect on the model molecule Rhodamine 6G. And also, two-photon fluorescence images showed that the silver nanoparticles had high performances in fluorescence enhancement.

Low Temperature One Step Synthesis of Barium Titanate: Particle Formation Mechanism and Large-scale Synthesis

The formation of BaTiO3 nanoparticles via the reaction of BaCl2, TiCl4 and NaOH in aqueous solution has been systematically studied. The formation of BaTiO3 from the ionic precursors has been elucidated to be a very rapid process, occurring at temperature higher than 60℃. Furthermore, the particle size could be controlled by the proper selection of the synthesis conditions (e.g. reactant concentration of 0.5—1.0mol·L-1, temperature of 80— 95℃ and pH≥13). A two-step precipitation mechanism was proposed. The first stage of the synthesis involved the formation of amorphous Ti-rich gel phase. The second stage of the synthesis was the reaction between the amor-phous phase and the solution-based Ba2+ ions, which led to the crystallization of BaTiO3. Based on the particle for-mation mechanism, a novel method, high gravity reactive precipitation, was proposed and used to mass production of BaTiO3 of average particle size of about 60 nm and with narrow particle size distribution. Because it could break up the amorphous Ti-rich gel into small pieces, intensify mass transfer, promote the reaction rate of amorphous Ti-rich gel with Ba2+ ions.

Synthesis of flowerlike nickel particles and their microwave absorbing properties

Two kinds of nickel particles with flower-like struc~＇es assembled with a number of nano-flakes were synthesized and the relationship of their morphology and microwave absorbing properties was studied. The electromagnetic parameters of these flower-like Ni were measured with vector network analyzer at 2-18 GHz frequency and the reflection losses （RL） with different sample thicknesses were calculated. The results indicate that the flower-like nickel-wax composites with the sample thickness less than 2 mm show excellent absorbing ability. This result is expected to play a guiding role in the preparation of the highly efficient absorber.

Hypoxia induces PGC-la expression and mitochondrial biogenesis in the myocardium of TOF patients

PGC-1α, a potent transcriptional coactivator, is the major regulator of mitochondrial biogenesis and activity in the cardiac muscle. The dysregulation of PGC-la and its target genes has been reported to be associated with congenital and acquired heart diseases. By examining myocardium samples from patients with Tetralogy of Fallot, we show here that PGC-1α expression levels are markedly increased in patients compared with healthy controls and positively correlated with the severity of cyanosis. Furthermore, hypoxia significantly induced the expression of PGC-1α and mitochondrial biogenesis in cultured cardiac myocytes. Mechanistic studies suggest that hypoxia-induced PGC-1α expression is regulated through the AMPK signaling pathway. Together, our data indicate that hypoxia can stimulate the expression of PGC-1α and mitochondrial biogenesis in the cardiac myocytes, and this process might provide a potential adaptive mechanism for cardiac myocytes to increase ATP output and minimize hypoxic damage to the heart.

Influence of graphite particle size and its shape on performance of carbon composite bipolar plate

Bipolar plates for proton exchange membrane fuel cell (PEMFC) where polymer is used as binder and graphite is used as electric filler were prepared by means of compression molding technology. Study on the effects of graphite particle size and shape on the bipolar plate performance, such as electrical conductivity, strength, etc. showed that with decrease of graphite particle size, bulk electrical conductivity and thermometric conductivity decreased, but that flexural strength was enhanced. After spherical graphite occurrence in flake-like form, the flexural strength of the bipolar plate was enhanced, electrical conductivity increased but thermal conductivity decreased in direction paralleling pressure direction, and both electrical conductivity and thermometric conductivity reduced in direction perpendicular to pressure direction.

Study on the Electrical Conductivity of Au Nanoparticle/Chloroform and Toluene Suspensions

Au nanoparticles capped by hexadecanethiol and dodecanethiol were chemically synthesized. The characteristics of electrical conductivity for the capped nanoparticles dissolved in chloroform and toluene solvents were investigated. The electrical conductivity of the samples is conspicuously Au nanoparticle concentration dependent. The results show that a rapid conductivity increases when the nanoparticle concentration increases from low value to a moderate value of 5.47 g/L and 11.22 g/L, which is capped by hexadecanethiol and dodecanethiol in chloroform solvent, and 2.77 g/L and 7.88 g/L in toluene solvent. The room-temperature dc conductivity σ dc of Au nanoparticle capped by hexadecanethiol is smaller than that capped by dodecanethiol in the whole range of Au nanoparticle concentrations. The conductivity of Au nanoparticle suspensions increases almost linearly in the temperature range in above two solvents.