奥氏体不锈钢深冷低温冲击试验方法研究

以液氦作为冷源,结合G-M低温制冷机,实现-196~-269℃深冷温度环境,探索深冷低温冲击试验方法。结果表明,试样从低温环境中取出后置于大气环境中,温度出现快速回升。对于不同试验低温,可采用不同方法进行试验。试验温度T=4.2K时,可采用制冷机预冷+液氦持续喷淋的方法进行降温。试验温度10≤T77K时,可采用玻璃容器填充气凝胶粉体对试样进行绝热保温处理;或根据试验温度以及回温测试结果,以一定的过冷温度补偿值保证试验温度。过冷温度补偿方法可满足常规冲击试验的要求,但需要相对较大的过冷温度补偿值;玻璃容器填充粉体包裹试样,可减缓试样温度回升,但对材料冲击吸收能量有一定影响,可用多试样冲击试验并进行修正以反映材料冲击韧性水平。     

基于色域划分的多通道打印机色彩校正

针对多通道喷墨打印机,提出一种将打印色域划分并在分割后的子区域内实施色彩校正的算法。首先建立打印机的呈色模型,进而分析了高维颜料空间的光谱冗余及色域划分的可行性,在此基础上设计色域划分方法,并对每个子区域实施色彩校正。区域划分降低了数据维数,消除了颜色冗余,且算法不受打印机颜料数目的限制。     

巧用Excel 2000设计光纤CATV前端光发机和光纤链路

根据光纤有线电视前端光发射机和光纤链路网络的设计要求，利用Microsoft Excel 2000内部公式与函数进行运算，编出具体操作方法，可大大简化运算过程和提高工作效率。     

Au/L-Met/GC电极的H2O2电催化氧化

在无额外的添加剂和保护剂的情况下,以柠檬酸钠还原氯金酸制得链状金纳米粒子,使用扫描电子显微镜（SEM）和透射电子显微镜（TEM）观察样品. 层层自组装技术可将金纳米粒子自组装,并分别以L-甲硫氨酸（L-Methionine,L-Met）、硫脲（Thiourea,TU）、丙烯基硫脲（Allyl thiourea,ATU）和聚乙烯吡咯烷酮（Polyvinylpyrrolidone,PVP）交联剂自组装于玻碳基底,即得金纳米粒子修饰电极. 以[Fe(CN)₆]^3-/4-氧化还原电对为探针,考察该修饰电极的电化学性质. Au/L-Met/GC电极有最佳电化学性能,循环伏安曲线和计时电流曲线测试表明,Au/L-Met/GC电极的H₂O₂电催化氧化有较高的灵敏度,线性范围2×10^-7 ~ 3×10^-3 mol·L^-1,检出限6.67×10^-8 mol·L^-1.     

Metal compound-mediated hydrolytic cleavage of oxidized insulin B chain:Regioselectivity and influence of peptide secondary structure

The interaction of oxidized insulin B chain(B)with cis-[Pd-(en)Cl2](en=ethylenediamine),cis-[Pd-(dtco-3-OH)Cl2](dtco-3-OH=dithiacyclooctan-3-ol)and CuCl2 was studied by electrospray inass spectrometry.It is discovered that the binding of Pd(Ⅱ)complexes and the sites of cleavage are highly dependent on the secondary structure and local environment of B.The hydrolytic cleavage of denatured B by Pd(Ⅱ)complexes was monitored by HPLC.The reaction is regioselective and follows first order kinetics with half-life of 4.8 days at 40℃.Two amide bonds,i.e.at Leu6-Cys7 and at Gly8-Ser9,which are close to the two potential Pd(Ⅱ)binding sites His5 and His10,are selectively cleaved.In the case of Cu(Ⅱ)ion as promoter,only one cleavage site was observed which is located at Gly8-Ser9 bond.These results provide improved understanding on the design of artificial metallopeptidase.     

Structure and electrospray mass spectrometry studies on dithiacyclooctan-3-ol-containing palladium (II) complex of trans -[Pd(dtco-3-OH)_2](ClO_4)_2·2DMSO

The structure of trans-[Pd(dtco-3-OH)2] (ClO4)2·2DMSO, in which dtco-3-OH is dithiacyclooctan-3-ol and DMSO is dimethyl sulfoxide, was determined by X-ray crystallographic analysis. The crystal data: space group pi, a = 0.7077(2) nm, b = 1.0788(1) nm, c = 1.1111(1) nm, α=67.710(8)°, β = 73. 59(2)°, γ = 85. 39(2)°,R1 = 0 . 0368 and Rw = 0.0998. The palladium (II) is coordinated by four sulfur atoms with a regular square planar configuration. The Pd-S distances are 0.2314(1) and 0.2317(1) nm, respectively. Both dtco-3-OH ligands are in the boat-chair configuration and two hydroxyl groups are on the opposite sites of the PdS4 coordination plane and are towards Pd(II). The Pd-O distance is 0. 285 nm, indicating a weak interaction between them. A typical hydrogen bond between the hydroxyl group of dtco-3-OH ligand and DMSO was observed in the crystal structure. An aqueous solution prepared with the crystals of the complex was used for the investigation of electrospray mass spectrometry ( ESMS ). Besid     

一种面向多光谱图像的打印分色方法

为解决多光谱图像打印输出问题,提出一种用非线性优化技术实现光谱图像打印分色的方法,以同时提高再现图像的光谱精度和色度精度.从分析打印系统成色机理及Neugebauer光谱模型入手,比较了图像光谱特性和色度特性对打印效果的影响,可知输出图像光谱误差和色度误差对打印质量均至关重要;据此构造了图像光谱误差和色度误差目标函数,分别反映再现图像的光谱精度和色度精度,并根据实际打印过程对各打印基色的墨量控制值进行约束;最后采用非线性优化方法,逐点计算图像光谱对应的墨量控制值,实现打印分色.实验表明,该方法能同时兼顾再现图像的光谱精度和色度精度,与仅考虑光谱误差的迭代分色方法相比,再现色度精度能提高约3～10倍.     

科技传播创新发展中科技期刊编辑面对的挑战及对策

科学技术进步和创新,推动着科技期刊传播的创新,科技期刊编辑人员的综合素质直接影响科技期刊的质量。通过对现在科技期刊编辑现状进行分析,面对凸显的差距和挑战,提出了相应的对策,并提倡充分利用科技手段加强科技信息传播和发展。     

两个小题目的启示

由求解两道小题目遇到的疑惑,给出与数学和教材相关的两点建议.     

溶胶-凝胶法制备的二氧化硅中肌红蛋白的苯胺羟化酶活性

用溶胶-凝胶制备了多孔透明的二氧化硅包埋肌红蛋白，在还原辅酶Ⅰ二钠盐(NADH)和黄素单核苷酸(FMN)的存在下，用可见光谱法测定了肌红蛋白苯胺羟基化反应的K_m和k_cat。表明包埋在二氧化硅中的肌红蛋白保持了苯胺羟化酶活性。