Synthesis, Characterisation and Antifungal Activities of Some New Copper(II) Complexes of Isomeric 3,5,7,7,10,12,14,14-Octamethyl-1,4,8,11-Tetraazacyclotetradecanes

Three isomeric Me(8)[14]anes, L(A), L(B) and L(C), undergo complexation with copper(II) salts to form a series of [CuLX(n)(H(2)O)(x)]X(y).(H(2)O)(z) complexes where L = L(A), L(B) and L(C); X = Cl, Br, NO(3); n, x, y and z may have values of 0, 1 or 2. The complexes have been characterised on the basis of analytical, spectroscopic, magnetic and conductance data. Further, the X-ray crystal structure of one complex, [CuL(B)(OH(2))(2)](NO(3))(2), has been determined. The antifungal activity of all three isomeric ligands and their complexes has been investigated against a range of phytopathogenic fungi.     

汽车仪表盘外壳模外装饰工艺仿真及其参数全局优化

以聚碳酸酯（PC）为薄膜材料,采用有限元方法对仪表盘外壳模外装饰（OMD）贴膜成型进行仿真,得到薄膜厚度的分布及其在x、y方向上的变形分布,在此基础之上,以三者的标准偏差同时最小来设计目标函数,采用试验设计的方法来建立近似模型,最后对贴膜工艺参数进行全局优化分析。结果表明,基于椭圆向基神经网络模型（EBF）模型采用自适应模拟退火算法（ASA）全局优化算法对OMD工艺参数进行优化分析所得到的结果无论在厚度分布还是变形精度上的效果都最好。     

Geometric relations between scales of small colour differences

Varying magnitude of colour differences from threshold up to moderate size in painted sample pairs at five CIE colour centers was estimated by grey scale assessment. Painted samples were produced for constant step width along the main axes of previously determined threshold (x,y,Y)‐ellipsoids with lightness variation at constant (x,y)‐chromaticity starting with threshold length and enlarging it five times for moderate magnitude of colour difference. Pairs were formed for linear extensions along axes and for diagonal combinations at equal step width between axes. The model under test assumes additive linear scale extension in constant proportions of the threshold (x,y,Y)‐ellipsoid for increasing magnitude of perceived colour difference and correlates perceptual main colour characters with main ellipsoid axes. Both assumptions were falsified to some degree: in general, magnitude of colour difference varies differently, though close to linear, and slightly subadditive for the three axes and for the different colour centers; the short (x,y)‐ellipse axis in some cases is not correlated with a perceptual hue vector component, and the main lightness direction sometimes is tilted in relation to the (x,y)‐plane. Three colour‐difference formulae do not provide better global predictions than the local (x,y,Y)‐ellipsoid formulae. The results may be used for more detailed modeling of colour‐difference formulae and for tolerance settings at different ranges of colour difference. © 1999 John Wiley & Sons, Inc. Col Res Appl, 24, 78–92, 1999     

A numerical method of calculating secondary current distributions in electrochemical cells

A numerical method is proposed based on the analogy between the potential distribution in an electrolytic solution and the temperature distribution in a heat-conducting medium. Thus the equation of non-steady-state heat conduction which contains a hypothetical temperaturev(x, y, t) is solved numerically with appropriate boundary conditions. In the steady state the distribution ofv(x, y, t) corresponds to the distribution of potentialφ _s (x,y) which satisfies Laplace's equation. The method is useful not only for conventional electrochemical cells but also for complicated systems such as a bipolar electrode for which boundary conditions provide neither the potential nor the current density at the electrode surface.     

The Limiting Distribution of the Residual Processes in Nonstationary Autoregressive Processes

The weak limit of the partial sums of the normalized residuals in an AR(1) process y _t = ρ y _{t −1} + e _t is shown to be a standard Brownian motion W ( x ) when |ρ| ≠ 1. However, when |ρ| = 1, the weak limit is W ( x ) plus an extra term due to estimation of ρ. Asymptotic behaviour of the partial sums is investigated with ρ = exp( c )/ n ) in the vicinity of unity, yielding a c -dependent weak limit as n ←∞, whose limit is again W ( x ) as | c | ←∞. An extension is made to nonstationary AR( p ) processes with multiple characteristic roots on the unit circle. The weak limit of the partial sums has close resemblance to that for the polynomial regression.     

Calculation of steady-state distributions of concentrations and potential controlled by diffusion and migration of ions

A numerical method is proposed for the calculation of concentration, potential, and current distributions in electrochemical cells controlled by diffusion and migration of ions. Thus a hypothetical variablev(x, y, t) is assumed to satisfy a differential equation which is similar to that of non-steady-state heat conduction and corresponds, at steady state, to Poisson's equation for the potential. The differential equation forv(x, y, t) and the diffusion-migration equations of ions are simultaneously solved by a finite difference method. Examples of calculation are given for single and mixed electrolyte solutions in one- and two-dimensional cells. The proposed method is applicable to systems in which bipolarity occurs.     

High-Temperature Electrical Properties of the Bi2.1Sr1.9(Ca1–xYx)Cu2Oy Solid Solution

By a combination of conventional physical property measurements and high-temperature electrical property studies, the solid solution limit, transport parameters, and potential defect regimes of the Bi_2.1Sr_1.9(Ca_{1 - x} Y _x )Cu₂O _y solid solution were established. A continuous solid solution extends to x = 0.7 or 0.8. The electrical properties indicate that the product of the hole density-of-states and mobility for semiconducting compositions is approximately an order of magnitude smaller than for the other p -type superconducting cuprates. A pronounced drop in hole concentration accompanies the tetragonal-to-orthorhombic transition at x = 0.5, whereafter superconductivity disappears. The electrical properties also indicate that a composition x change occurred reversibly below 1100°C.     

密码替换后人促红素基因在大肠杆菌中的高效表达及工程菌的发酵

目的　研究人工合成的hEPO基因在大肠杆菌中高效表达及工程菌高密度发酵条件。方法　将hEPO基因中大部分大肠杆菌稀有密码子替换成使用频率较高的密码子 ,人工合成hEPO全基因 ,然后将其插入表达载体PBV2 2 0中 ,转化大肠杆菌DH5α ,挑选构建正确的PBV2 2 0 hEPO DH5α菌落 ,经升温诱导 ,SDS- PAGE和Westernblot鉴定表达产物 ;观察改变培养基、培养时间、pH及溶氧量等条件对表达产物的影响。结果　经酶切分析 ,DNA测序鉴定 ,人工合成的hEPO基因已正确构建到表达载体中。通过高密度发酵培养 ,最终菌体密度达A6 0 0 =30 (相当于菌体 35g L) ,hEPO表达量达 30 %左右。结论　人工合成的hEPO基因在大肠杆菌中得到高效表达 ,并确定了该工程菌高密度发酵的适宜条件。     

Stability and Oxidation Properties of RE-α-Sialon Ceramics (RE = Y, Nd, Sm, Yb)

Oxidation studies of hot-pressed RE-α-sialons, RE _x -Si_{12-4.5 x} Al_{4.5 x} O_{1.5 x} N_{16-1.5 x} (with x = 0.40 for RE = Nd, Sm, Yb; and x = 0.48 for RE = Y) were carried out in oxygen in a TG apparatus for ca. 20 h. Very good oxidation resistance was found for the Yb-doped samples, with parabolic rate constants K _p similar/congruent 0.09 10^-6-3 10^-6 mg²cm^-4s^-1 in the temperature range 1250-1350°C. The promising performance of this material was corroborated by long-term oxidation experiments (5 days) in air at 1350°C. Although the oxidation kinetics can be described by simple equations related to the parabolic rate law (e.g., the arctan equation, Δ W / A ₀=α arctan bt + c t ), the oxidation process in these materials is likely to be complex. The significantly lower oxidation resistance of the RE = Nd, Sm doped α-sialons, especially at higher temperatures, is related to the formation of melilite, RE₂Si_{3− y} Al _y O_{3+ y} N_{4− y} ( y ∼ 1), in these systems. The melilite phase is also responsible for the thermal instability of the Nd- and Sm-α-sialons.     

ON THE RECURSIVE FITTING OF SUBSET AUTOREGRESSIONS

Abstract. In fitting a vector autoregressive process which may include lags up to and including lag K , we may wish to search for the subset vector autoregressive process of size k (where k is the number of lags with non-zero coefficient matrices, k = 1, 2, K ) which has the minimum generalized residual variance. This paper provides a recursive procedure, which is initialized by evaluating all 'forwardand'backward' autoregressions in which k = 1. The recursion then allows one to develop successively all subsets of size k = 2, k = 3 up to k = K .
The optimum subset vector autoregression is found by employing the proposed recursive procedures in conjunction with model selection criteria. This approach is used on simulated data to assess its performance and to re-examine the annual trappings of the Canadian lynx investigated by Tong (1977).     

Cation Ordering and Domain Boundaries in Ca[(Mg1/3Ta2/3)1−xTix]O3 Microwave Dielectric Ceramics

Cation ordering and domain boundaries in perovskite Ca[(Mg_1/3Ta_2/3)_{1− x} Ti _x ]O₃ ( x =0.1, 0.2, 0.3) microwave dielectric ceramics were investigated by high-resolution transmission electron microscopy (HRTEM) and Rietveld analysis. The variation of ordering structure with Ti substitution was revealed together with the formation mechanism of ordering domains. When x =0.1, the ceramics were composed of 1:2 and 1:1 ordered domains and a disordered matrix. The 1:2 cation ordering could still exist until x =0.2 but the 1:1 ordering disappeared. Neither 1:2 nor 1:1 cation ordering could exist at x =0.3. The space charge model was used to explain the cation ordering change from 1:2 to 1:1 and then to disorder. A comparison between the space charge model and random layer model was also conducted. HRTEM observations showed an antiphase boundary inclined to the (111) _c plane with a projected displacement vector in the 〈001〉 _c direction and ferroelastic domain boundaries parallel to the 〈100〉 _c direction.     

紫外-可见分光光度法测定奶粉中的香兰素含量

采用紫外-可见分光光度法测定了几种奶粉中的香兰素含量。在最大吸收波长435.0nm处,其吸光度与香兰素含量呈正比,线性方程为y=7.493 42x+0.001 3(r=0.999 7),线性范围为0.010 4～0.165 2g/L,加标回收率为98.6%,RSD为0.34%。该方法重现性好,适用于食品中香兰素含量的测定。     

茚虫威10%悬浮剂的液相色谱分析方法

采用Diamond C18不锈钢柱[150 mm×4.6 mm(i.d.),5μm]和二极管阵列检测器,以甲醇-水混合溶剂(80∶20,v/v)为流动相,流速1.0 mL/min、检测波长310 nm和柱温35℃,建立了茚虫威制剂10%悬浮剂的高效液相色谱分析方法。茚虫威在0.5~10 mg/L的浓度范围内,其峰面积(y)与质量浓度(x)呈现良好的相关性,其线性回归方程为y=23 372x+3 238.2,R2=0.999 3。在10%悬浮剂中,茚虫威5个添加浓度水平的平均回收率为99.29%,相对标准偏差(RSD)为1.05%,说明所建立的方法快速、灵敏度高、重现性好,可用于茚虫威10%悬浮剂产品质量控制与分析。     

Positive Temperature Coefficient of Electrical Resistivity below 150 K in Barium Strontium Titanate

The resistivity of Ba_{(1– y )(1– x )}Sr _y (1– x )La _x TiO₃ceramics with x = 0.0025 and y = 0.25, 0.5, 0.75, and 0.9 was measured between 50 and 400 K. A resistivity anomaly corresponding to the positive temperature coefficient of electrical resistivity (PTCR) effect was observed for all compositions. The onset temperature decreased from 320 K ( y = 0.25) to 70 K ( y = 0.9). The extent of the PTCR effect was significantly enhanced for the strontium-rich composition and reached ∼8 orders of magnitude for y = 0.9. These results strongly suggested the possibility to fabricate PTCR devices based on (Sr,Ba)TiO₃ ceramics for application at cryogenic temperatures.     

In_(1-x)Ga_xAs_yP_(1-y)/GaAs应变量子阱中电子和空穴能带的组分调制1

本文采用模型固体理论计算了In1-xGaxAsyP1-y/GaAs应变量子阱中电子和空穴的能带结构,研究了组分对能带的调制作用.结果表明,In1-xGaxAsyP1-y/GaAs量子阱的能带类型及带隙依赖于阱材料In1-xGaxAsyP1-y的组分。当y=1.0,x在0~1.0范围时,量子阱In1-xGaxAsyP1-y/GaAs的能带为类型Ⅰ;当y=0.6,x在0.32~1.0范围时,量子阱的能带为类型Ⅱ。即通过调整阱材料组分,可以方便实现这种量子阱的能带转型(即类型I-类型Ⅱ的转变)。     

The Li2O–Nb2O5–TiO2 Composite Microwave Dielectric Ceramics with Adjustable Permittivities

A group of new y M-phase/(1− y ) Li_{2+ x} Ti_{1−4 x} Nb_{3 x} O₃ composite ceramics with adjustable permittivities for low-temperature co-fired ceramic applications was initially investigated in the study. The 0.5 M-phase/0.5 Li_{2+ x} Ti_{1−4 x} Nb_{3 x} O₃ ( x =0.01, 0.02, 0.04, 0.06, 0.081) composite ceramics were first investigated to find the appropriate "Li₂TiO₃ss" composition ( x value). The best dielectric properties of ɛ_r=40.1, Q × f values up to 9318 GHz, τ_f=25 ppm/°C, were obtained for the ceramics composites at x =0.02. Based on the good dielectric properties, the suitable "Li₂TiO₃ss" composition with x =0.02 was mixed with the Li_1.0Nb_0.6Ti_0.5O₃ powder as the ratio of y "M-phase"/(1− y ) "Li₂TiO₃ss" ( y =0.2, 0.4, 0.5, 0.6, 0.8). By adjusting the y values, the group of composite ceramics could exhibit largely are adjustable permittivities varying from ∼20 to ∼60, while Q × f and τ_f values relatively good. Nevertheless, in this study, because there are interactions between the M-phase and Li₂TiO₃ss during sintering process, their microwave dielectric properties could not be predicted precisely by the empirical model.     

Estimation equations for practical use on lightness-reflectance (L/Y) ratios in the whole chromaticity gamut

A multiple regression analysis is reported to predict L/Y ratios as a function of chromaticity coordinates x, y. the specified variables were selected statistically from the 20 terms of Ψ^mψⁿ. the quantities Ψ, ψ are the transformed values of x, y, respectively, and 1 ≦ m + n ≦ 5. the contour lines of equal L/Y ratios are estimated in the whole chromaticity gamut including spectral colors by using each of the regression equations with 6, 9, and 20 specified variables. the regression equations with 20 specified variables can satisfactorily predict the corresponding experimental results. In case of regression equations with 6 specified variables, the predicted contour lines are significantly different in shape from those of the corresponding experiments. the same defects are found in the Ware-Cowan equation only using 4 specified variables recommended by CIE Division 1 for further tests.     

Adaptive Fourier Series and the Analysis of Periodicities in Time Series Data

A Fourier series decomposes a function x ( t ) into a sum of periodic components that have sinusoidal shapes. This paper describes an adaptive Fourier series where the periodic components of x ( t ) may have a variety of differing shapes. The periodic shapes are adaptive since they depend on the function x ( t ) and the period. The results, which extend both Fourier analysis and Walsh–Fourier analysis, are applied to investigate the shapes of periodic components in time series data sets.     

明胶溶液浓度、比重与温度的关系

提出了一种新的明胶溶液的浓度与其比重和测量温度间的关系图,以及三者之间的函数关系式。具有操作简捷、快速、所得结果准确度高的特点。     

Enhancement of Polar Kerr Effect by Forming Cu Nanoparticles on Ni Surface

Cu(x)/Ni(y)/glass bi-layer films, with x ranging from 10 to 310 A andy = 85 A, were made by the vapor evaporation method in a good vacuum. The surface morphology of each bi-layer was examined by an atomic force microscope (AFM). The results show that when x = 10 and 40 A, respectively, there are, in particular, a large number of Cu nanoparticles (or nano-islands) forming on top of the Ni surface.As a result, we observed considerable enhancement of either the polar Kerr rotation (θk) or the extraordinary Hall coefficient (Rs) at these two thicknesses (e.g. checking the figure below). As well known, the penetration depth (δp), of the polarized electrons, crossing the Cu/Ni interface from the Ni to the Cu layer, is of the order of the electron mean free path, i.e. δp =(3/8)[Cu≈90 A. in the Cu layer. Therefore.the strong enhancement of θK is due to the enhanced surface plasma resonance effect on the polarized Cu nanoparticles. Moreover. the formation of Cu nanoparticles roughens the bi-layer's surface greatly.That means the enhancement of Rs is due to the increase of the surface resistivity ρs.