自由基浓度测定方法的再验证及其在煤化学中应用

对前人建立的标准曲线法测煤中自由基浓度进行优化,以DPPH标准样品和基准样品的二次积分面积比值为新参数,结果显示新参数标准曲线法的实测值与理论值相对误差都在5%以内;重复性、复现性实验的相对标准偏差都小于3%。将新参数标准曲线法用于分析不同煤化程度煤和新疆黑山煤(HS)沥青质的自由基浓度,发现随着煤化程度增加,其煤中自由基浓度逐渐增大,从低阶褐煤的8.531×10~(17)/g上升到高阶无烟煤3.37899×10~(19)/g;而在HS煤液化过程中,随着加氢液化温度的升高,其沥青质自由基浓度逐渐下降,从290℃的1.5793×10~(18)/g降到450℃的7.410×10~(17)/g,沥青质自由基浓度变化趋势与其产率变化趋势相一致。     

射频等离子硫钝化GaAs(100)的表面特性

采用射频等离子方法,对Ga As(100)衬底片表面进行干法硫等离子体钝化,旨在得到性能稳定含硫钝化层。样品经过360℃温度条件下的快速热退火,光致发光(PL)测试表明,钝化后的样品PL强度上升了71%。同时,钝化样品的稳定性测试结果表明,样品放置在实验室空气中30 d,其PL强度未出现明显变化,说明Ga As的等离子体干法硫钝化具有较好的性能稳定性。     

Al2O3/SnO2 Co-Nanoparticle Modified Grafted Collagen for Improving Thermal Stability and Infrared Emissivity

Al2O3/SnO2 co-nanoparticles were prepared with a modified sol-gel technique followed by a thermal treatment process. With these co-nanoparticles the grafted collagen-Al2O3/SnO2 nanocomposites were obtained using a supersonic dispersion method. X-ray diffraction, FT-IR analysis, transmission electron microscopy, TGA/DTA and infrared emissivity test were performed to characterize the resulting nanoparticles and nanocomposites, respectively. The Al2O3/SnO2 co-nanoparticles showed a narrow distribution of size between 20-40 nm and could be uniformly absorbed on the tri-helix scaffolds of the grafted collagen without any aggregation. The nanocomposites possessed better thermal stability and substantially lower infrared emissivity than the grafted collagen and Al2O3/SnO2 co-nanoparticles with an increase of degradation temperature from 39 to 210 ℃ and a decrease of infrared emissivity from 0.850 of the grafted collagen and 0.708 of the Al2O3/SnO2 co-nanoparticles to 0.424, which provided a potential application of the nanocomposites to areas such as photoelectronics.     

LOW-FREQUENCY INTERNAL FRICTION STUDY FOR SrBi2Ta2O9 FERROELECTRIC CERAMICS

Low-frequency internal friction (IF) of SrBi₂Ta₂O₉(SBT) ceramics has been measured at temperatures ranging from 293 to 623 K. Two IF peaks, with their locations around 393 K (P1) and 569 K (P2) (f≈1.58 Hz), respectively, are observed. P1 is found to be associated with a relaxation process with activation energy of 0.97 eV and pre-exponential factor of 3.58×10^-14 s. Peak shape analyses reveal that P1 can be well described by a broadened Debye peak with the width parameter β from 2.70 to 2.92. The mechanism responsible for P1 is proposed to be relaxation of oxygen vacancies near domain walls(DWs). P2 is considered to arise from viscous motion of DWs since it shows characteristics of static hysteresis type. Comparisons for the IF behavior between SBT and Pb(Zr, Ti)O₃(PZT) suggest that in SBT oxygen vacancies are much less localized near DWs than that in PZT. This result provides a possible explanation for the weak DW pinning due to oxygen vacancies in SBT.     

A FURTHER STUDY OF THE THEORY OF ELASTIC CIRCULAR PLATES WITH NON－KIRCHHOFF－LOVE ASSUMPTIONS

ＡＦＵＲＴＨＥＲＳＴＵＤＹＯＦＴＨＥＴＨＥＯＲＹＯＦＥＬＡＳＴＩＣＣＩＲＣＵＬＡＲＰＬＡＴＥＳＷＩＴＨＮＯＮ－ＫＩＲＣＨＨＯＦＦ－ＬＯＶＥＡＳＳＵＭＰＴＩＯＮＳＣｈｉｅｎＷｅｉ－ｚａｎｇ（钱伟长）ＲｕＸｕｅ－ｐｉｎｇ（茹学萍）（ＳｈａｎｇｈａｉＵｎｉ...     

The global analysis of higher order nonlinear dynamical systems and the application of cell-to-cell mapping method

In this paper, the general characteristics and the topological consideration of the global behaviors of higher order nonlinear dynamical systems and the characteristics of the application of cell-to-cell mapping method in this analysis are expounded. Specifically, the global analysis of a system of two weakly coupled van der Pol oscillators using cell-to-cell mapping method is presented.The analysis shows that for this system, there exist two stable limit cycles in 4-dimensional state space, and the whole 4-dimensional state space is divided into two almost equal parts which are, respectively, the two asymototically stable domains of attraction of the two periodic motions of the two stable limit cycles. The validities of these conclusions about the global behaviors are also verified by direct long term numerical integration. Thus, it can be seen that the cell-to-cell mapping method for global analysis of fourth order nonlinear dynamical systems is quite effective.     

时间离散神经振子中的多吸引子共存

本文给出一类耦合时间离散神经网络振子动力学的理论分析和数值模拟结果,重点分析了多吸引子共存的震子及其吸引域的边界（不稳定的周期的周期不变坏）,研究了多上子共趣及耦合强度变化对于神经信号处理保,如受激盛同步和对模式形成有重要影响的锁频现象。     

测度熵计算中映射不变分布的应用

构造计算测度熵(MetricEntropy)的马尔可夫划分(MarkovPartition)时,对于非线性映射采取等似然假设,影响精度。提出用计算映射的不变分布来进行改进;对逻辑映射导出映射不变分布的算式及迭代格式,进行了测度熵的计算;计算表明,迭代次数不多时即能得出较好结果。     

部分药、食两用花卉中微量元素含量分析

采用原子吸收分光光度法对部分药、食两用花卉中微量元素进行了分析,并与普通叶菜类进行了对比。     

重瓣红玫瑰组织培养中培养基和培养条件的筛选

为解决重瓣红玫瑰繁殖周期长,不能满足日益增长的市场需求.以山东平阴地区培育的一种重瓣玫瑰作为实验材料,利用其带腋芽茎段为外植体,进行腋芽初代培养、继代培养、无菌苗的生根及移栽,探索其诱导、增殖、生根的最佳培养基配比及培养条件.结果表明,重瓣红玫瑰诱导芽的最佳培养基配比为MS culture medium(MS)+6-苄氨基腺嘌呤(6-BA)1.5 mg·L~(-1)+萘乙酸(NAA)0.1 mg·L~(-1)+蔗糖30 g·L~(-1)+0.8%琼脂;芽增殖的最佳培养基配比为MS+6-BA 2 mg·L~(-1)+NAA 0.25 mg·L~(-1)+蔗糖30 g·L~(-1)+0.8%琼脂;最佳生根培养基为1/2MS+吲哚丁酸(IBA)1 mg·L~(-1)+蔗糖30 g·L~(-1)+0.8%琼脂+黑暗条件培养.