一种电大尺寸组合体散射的快速计算方法

采用自适应多层快速多极子算法分析电大尺寸组合体的雷达散射截面。推导了组合体表面的积分方程,通过将基函数和权函数分别用不同空间位置上的点源函数展开,自适应多层快速多极子算法实现了阻抗积分的快速计算,通过采用射线传播法,远场近似和对称性计算法则使转移因子的计算效率大大提高,所有转移过程可由快速傅里叶变换计算完成。这种算法计算组合体散射时所需的计算时间和内存显著降低,且数值计算结果和实际测试结果吻合良好。     

基于预测编码与DCT变换编码的比较

深入分析了预测编码与DCT变换编码的异同点，并从编码增益、块效应系数、预测与变换与变换前后的能量关系等多方面比较了两种编码的优缺点。     

高铁赤泥中铝的赋存状态及铝铁分离技术研究

针对拜耳法高铁赤泥无害化处置与资源化利用难题,研究了高铁赤泥中铝的赋存状态及其对铝铁分离的影响。借助XRD、铁化学物相分析、SEM-EDS等检测手段,主要关注高铁赤泥的化学组成、矿物组成以及铝的赋存状态等工艺矿物学特征。赤泥的主要组成矿物为褐铁矿、赤铁矿和铝针铁矿和钛铁矿。查明赤泥中的铁主要以针铁矿、赤铁矿的形式存在;铝主要以类质同象存在于针铁矿中,形成铝针铁矿,部分以三水铝石的形式存在,铁铝共生关系密切。赋存于针铁矿中的铝采用常规物理分选方法无法实现铝铁分离,利用磁化焙烧和悬浮焙烧预还原-电炉熔炼工艺分别尝试对高铁赤泥进行铝铁分离,磁化焙烧能够实现赤铁矿、针铁矿向磁铁矿的定向转化,但不能有效破坏铁矿物中铝的类质同象结构,无法实现铝和铁的分离,导致磁选铁精矿中TFe品位低、Al2O3含量高;悬浮焙烧预还原-电炉熔炼工艺能有效实现高铁赤泥的铁铝分离与综合利用,当原料TFe品位为46.85%、Al2O3含量为13.31%时,可获得TFe 92.86%的炼钢用生铁,同时所得到的矿渣产品可以作为生产铝酸盐水泥熟料的原料。可见,悬浮焙烧预还原-电炉熔炼工艺可以有效破坏矿石内部铝和铁类质同象的晶格结构,实现了铝铁的高效分离,为高铁赤泥的无害化处置与资源化利用提供了新途径。     

Generation and Identification of the Number of Copies of Exogenous Genes and the T-DNA Insertion Site in SCN-Resistance Transformation Event ZHs1-2

Soybean cyst nematode (SCN, Heterodera glycines Ichinohe) causes an estimated economic loss of about USD 3 billion each year in soybean (Glycine max L.) production worldwide. Overexpression of resistance genes against SCN provides a powerful approach to develop SCN resistance cultivars in soybean. The clarification of molecular characterization in transformation events is a prerequisite for ecological risk assessment, food safety, and commercial release of genetically modified crops. Here, we generated transgenic events harboring the BCN (beet cyst nematode) resistance Hs1^pro−1 gene using the Agrobacterium-mediated method in soybean, evaluated their resistance to SCN infection, and clarified the molecular characterization of one of the transformation events. Five independent and stable inheritable transformation events were generated by an Agrobacterium-mediated transformation method. SCN resistance tests showed the average number of developed females per plant and female index (FI) in T4 ZHs1-1, ZHs1-2, ZHs1-3, ZHs1-4, and ZHs1-5 transformation events were significantly lower than that in the nontransgenic control. Among these, the ZHs1-2 transformation event had the lowest number of developed females per plant and FI. Southern hybridization showed the exogenous target Hs1^pro−1 gene was inserted in one copy and the Bar gene was inserted two copies in the ZHs1-2 transformation event. The exogenous T-DNA fragment was integrated in the reverse position of Chr02: 5351566–5231578 (mainly the Bar gene expression cassette) and in the forward position of Chr03: 17083358–17083400 (intact T-DNA, including Hs1^pro−1 and Bar gene expression cassette) using a whole genome sequencing method (WGS). The results of WGS method and Southern hybridization were consistent. All the functional elements of exogenous T-DNA fragments were verified by PCR using specific primer pairs in the T5 and T6 ZHs1-2 transformation events. These results demonstrated that the overexpression of Hs1^pro−1 gene enhanced SCN resistance, and provide an important reference for the biosafety assessment and the labeling detection in transformation event ZHs1-2.     

跳回失稳研究

本文以单元形函数作为单位分解函数，位移间断用富集节点的附加自由度表示，建立了允许单元内部位移非连续的统一位移场函数。结合粘结裂纹模型，研究了结构从延性到脆性失稳的特性以及引起脆性破坏的影响因素。数值计算表明：增加脆性指数可以提高结构的承载稳定性；初始预制缝可以增加结构延性但会降低极限承载力。     

Having a Same Type IIS Enzyme’s Restriction Site on Guide RNA Sequence Does Not Affect Golden Gate (GG) Cloning and Subsequent CRISPR/Cas Mutagenesis

Golden gate/modular cloning facilitates faster and more efficient cloning by utilizing the unique features of the type IIS restriction enzymes. However, it is known that targeted insertion of DNA fragment(s) must not include internal type IIS restriction recognition sites. In the case of cloning CRISPR constructs by using golden gate (GG) cloning, this narrows down the scope of guide RNA (gRNA) picks because the selection of a good gRNA for successful genome editing requires some obligation of fulfillment, and it is unwanted if a good gRNA candidate cannot be picked only because it has an internal type IIS restriction recognition site. In this article, we have shown that the presence of a type IIS restriction recognition site in a gRNA does not affect cloning and subsequent genome editing. After each step of GG reactions, correct insertions of gRNAs were verified by colony color and restriction digestion and were further confirmed by sequencing. Finally, the final vector containing a Cas12a nuclease and four gRNAs was used for Agrobacterium-mediated citrus cell transformation. Sequencing of PCR amplicons flanking gRNA-2 showed a substitution (C to T) mutation in transgenic plants. The knowledge derived from this study could widen the scope of GG cloning, particularly of gRNAs selection for GG-mediated cloning into CRISPR vectors.     

某砌体房屋底层大空间改造设计

已有砖砌体房屋底层常因功能改变而需要更大的使用空间,部分承重墙体的抽除必将导致传力途径的改变,故需对原有结构进行加固。阐述了托换技术在房屋改造加固中的应用,同时对托换技术的各设计阶段,包括基础设计、结构设计等作了分析。     

EPON+LAN与EPON+EoC接入方式的选择

介绍了EPON系统与EoC的组成及原理,以此引申出EPON+LAN、EPON+EoC的技术模型,通过EPON+LAN与EPON+EoC的技术对比,根据其优缺点,结合双向网络建设的实际情况,分析双向网络改造中对EPON+LAN与EPON+EoC接入方式的选择。     

Q235碳素钢超细铁素体在奥氏体内的形核

利用扫描电镜观察了Q235碳素钢形变强化相变过程中超细铁素体在奥氏体内部的形核;使用背散射电子衍射(EBSD)技术分析了析出的铁素体取向.结果表明,随内、外界条件不同,奥氏体内有两类典型的铁素体形核地点:形变带及奥氏体晶界附近的形变不均匀区原始奥氏体晶粒尺寸的增加,形变温度的降低有利于铁素体的形变带形核.在A₃-A_r3的超细铁素体最佳形成温度区间,靠近A₃形变可使铁素体及第2组织均匀分布.形变带形核造成带状分布的铁素体及第2相,不仅形貌上出现方向性,铁素体取向也出现择优.     

铁基合金的贝氏体基元及其生长演化

用透射电镜研究了 Fe-C-Mo 和 Fe-C-Si-Mn 合金中温转变早期产物的组织形态,发现在整个中温转变范围非平衡先析型转变都是按贝氏体铁素体相变基元形成及其扩散生长演化方式进行,说明经生长演化一些时间后的基元难于作为判断贝氏体形核机制的形态学依据。从基元生长演化进程区分了低碳贝氏体和板条马氏体。