基于生物延迟发光评价玉米萌发期抗旱性的方法

玉米种子萌发期抗旱性评价是节水农业研究中的难点和热点问题之一,生物延迟发光分析技术的应用有可能解决这一问题。采用生物延迟发光评价方法研究了玉米种子萌发期的抗旱性能力,探讨了在渗透势-0.1 MPa和-0.3 MPa的PEG-6000溶液中萌发的玉米品种万瑞168号和堰单8号延迟发光的变化规律。结果表明,万瑞168号和堰单8号玉米品种的延迟发光积分强度都随着萌发进程逐渐升高,-0.1 MPa和-0.3 MPa的PEG-6000溶液形成的干旱胁迫对两个玉米品种延迟发光积分强度的升高有不同的抑制作用,胁迫强度越大,两个品种延迟发光积分强度的差异就越大。研究还发现,在干旱胁迫下萌发的万瑞168号和堰单8号玉米延迟发光相对变化率R_DL与种子萌发抗旱指数和储藏物质转运率的变化是一致的,依据干旱胁迫下种子萌发过程中延迟发光积分强度相对变化率R_DL的大小可以评价玉米种子萌发期抗旱性的强弱。     

Trigonometrical sums connected with the chiral Potts model,Verlinde dimension formula,two-dimensional resistor network,and number theory

We have recently developed methods for obtaining exact two-point resistance of the complete graph minus N$N$ edges. We use these methods to obtain closed formulas of certain trigonometrical sums that arise in connection with one-dimensional lattice, in proving Scott’s conjecture on permanent of Cauchy matrix, and in the perturbative chiral Potts model. The generalized trigonometrical sums of the chiral Potts model are shown to satisfy recursion formulas that are transparent and direct, and differ from those of Gervois and Mehta. By making a change of variables in these recursion formulas, the dimension of the space of conformal blocks of SU(2)$SU\left(2\right)$ and SO(3)$SO\left(3\right)$ WZW models may be computed recursively. Our methods are then extended to compute the corner-to-corner resistance, and the Kirchhoff index of the first non-trivial two-dimensional resistor network, 2×N$2\times N$. Finally, we obtain new closed formulas for variant of trigonometrical sums, some of which appear in connection with number theory.     

激光冲击与渗碳复合工艺改善12CrNi3A钢磨损性能

为了提高12CrNi3A钢渗碳层质量及其抗磨损性能,提出了激光冲击与渗碳不同顺序复合的工艺方法。球磨实验结果表明,相比渗碳处理,激光冲击后渗碳试样的比磨损率降低了51%,而渗碳后激光冲击强化试样的比磨损率降低了13%,说明激光冲击后渗碳的复合工艺能更好地改善抗磨损性能。在摩擦系数差别不大的情况下,抗磨损性能的提升与显微硬度提高、微观组织变化有关,从这两方面讨论抗磨损性能提升的机理。研究表明:激光冲击强化可促进渗碳的过程,强化后渗碳形成的渗碳层结构致密,大量细小碳化物形成,固溶强化、第二相强化作用增强,显微硬度增大,从而提高抗磨损性能;而渗碳后激光冲击强化只使渗层表面发生了形变强化,与渗碳工艺相比,显微硬度略有提高,抗磨损性能提高有限。     

The influence of interfacial barrier engineering on the resistance switching of In₂O₃:SnO₂/TiO₂/In₂O₃:SnO₂ device

The I–V characteristics of In2O3:SnO2/TiO2/In2O3:SnO2 junctions with different interfacial barriers are inves- tigated by comparing experiments. A two-step resistance switching process is found for samples with two interfacial barriers produced by specific thermal treatment on the interfaces. The nonsynchronous occurrence of conducting filament formation through the oxide bulk and the reduction in the interfacial barrier due to the migration of oxygen vacancies under the electric field is supposed to explain the two-step resistive switching process. The unique switching properties of the device, based on interfacial barrier engineering, could be exploited for novel applications in nonvolatile memory devices.     

分压与限流线路特性分析

在电学实验的创新设计类问题中,常常涉及到滑线变阻器的分压线路和限流线路。本文对滑线变阻器的分压线路和限流线路的特性作一较系统的分析,对涉及到此类问题的实际工作具有指导意义。     

Preparation and properties of electroless Ni-P-SiO2 composite coatings

Dispersible SiO₂ nanoparticles were co-deposited with electroless Ni-P coating onto AISI-1045 steel substrates in the absence of any surfactants in plating bath. The resulting Ni-P/nano-SiO₂ composite coatings were heat-treated for 1 h at 200 °C, 400 °C, and 600 °C, respectively. The hardness and wear resistance of the heat-treated composite coatings were measured. Moreover, the structural changes of the composite coatings before and after heat treatment were investigated by means of X-ray diffraction (XRD), while their elemental composition and morphology were analyzed using an energy dispersive spectrometer (EDS) and a scanning electron microscope (SEM). Results show that co-deposited SiO₂ particles contributed to increase the hardness and wear resistance of electroless Ni-P coating, and the composite coating heat-treated at about 400 °C had the maximum hardness and wear resistance.     

(CH3)2和(NH2)2基团修饰的齐聚苯乙炔分子电子输运性质研究

采用密度泛函理论和非平衡格林函数相结合的方法研究了S原子作为单、双端基的(CH₃)₂-OPE (齐聚苯乙炔)和(NH₂)₂-OPE分子在金电极间的电子输运性质. 通过第一性原理优化计算获得分子部分稳定结构, 再置于Au电极之间构成两极系统, 然后再优化整个两极系统获得稳定结构. 另外, 通过非平衡格林函数方法计算了两极系统的电子输运性质. 计算结果表明, 不同的修饰基团和桥接方式可以导致两极系统的开关效应、负微分电阻行为和整流行为等不同的电子输运性质. 通过计算不同偏压下的分子体系投影轨道电子分布、透射谱、态密度, 对这些新异的电输运性质出现的机理进行了解释.     

快放电直线型变压器驱动源磁芯脉冲损耗特性

建立了快脉冲磁芯损耗特性测试平台,对比研究了50 m的DG6硅钢和25 m的2605TCA非晶两种材料磁芯损耗特性;采用一种新的特征参量(磁芯单位面积上激磁电压陡度)来规范磁芯的激磁电压条件,使得实验结果与快放电直线型变压器驱动源实际工作条件下磁芯性能具有可比性;通过测量初级漏电流及次级开路电压,获得了相同激磁条件下两种磁芯等效损耗电阻的大小,50 m 的DG6硅钢磁芯损耗约为25 m的2605TCA非晶磁芯损耗的4倍;计算了两种材料磁芯总损耗中涡流损耗所占的比例,50 m的DG6硅钢磁芯涡流损耗占总损耗的75%,25 m的2605TCA非晶磁芯涡流损耗占总损耗的28%。     

用于脉冲功率装置测量的混合式高压分压器

为准确测量脉冲放电电压,提出了固液混合式高压分压器的原理与结构,并进行了标定和实验测试。用简化模型分析了分压器系统的理想响应条件,讨论了两级分压的衰减特性,提出了控制误差的方法。通过负载标定,得到分压器脉冲电压频率响应大于2.9 MHz,最长脉冲宽度40 s,分压比(或衰减系数)为2.60 kV/V,测量误差小于5%。该高压分压器具有造价低、制作易,同时适于ns到s级脉冲电压的测量等优点,可以在实验室中得到应用。