Waveform optimization for integrated square-wave detection of biogenic amines following their liquid chromatographic separation

Results are described from research designed to optimize the potential–time (E–t) waveform applied in integrated square-wave detection (ISWD). More specifically, goals of this study included the minimization of background signal with maximization of the signal-to-background ratio (S/B) for application of ISWD to polyamines separated by high performance cation-exchange liquid chromatography (LC). This effort included optimization of the separation procedure because the background signal was determined to be a sensitive function of the composition of the chromatographic mobile phase. Initial estimates of potential parameters were obtained from an off-line voltammetric study of 1,3-diaminopropane at a gold rotated disk electrode (RDE). Final waveform optimization was based on data obtained during on-line application of the ISWD waveform for 1,3-diaminopropane injected at various times during execution of the mobile phase gradient. The maximum potential in the waveform (E_MAX) was chosen to achieve formation of surface oxide (AuO) with concomitant oxidation of the amine without evolution of O₂. The minimum potential in the waveform (E_MIN) was chosen to achieve reduction of the surface oxide generated at E_MAX with minimal reduction of dissolved O₂.     

Efficient interface conditions for the semi-vectorial finite-difference beam propagation method

Efficient interface conditions (EICs) are derived for the propagation equation using the slowly varying envelope approximation for the dominant electric field component. At the interface between two different media, the two lateral second derivatives in the discretized propagation equation are adapted such that the discretized modal field equation is correct up to second order in the lateral grid spacing. Since the error term is then of the order of the lateral grid spacing, our EICs are first-order EICs. These interface conditions are compared with well-known zero-order EICs derived by Stern and Kim and Ramaswamy. It is shown that the first-order EICs yield faster convergence to the exact effective index value as the lateral grid spacing is decreased than do the zero-order EICs. It turns out that our EICs are very much like those derived by Vassallo. Using essentially the same method, he derived EICs of second and first order for the field component respectively parallel and perpendicular, to the interface. Hence the accuracy of his EICs is one order higher for the field component parallel to the interface, although it introduces an extra asymmetry in the propagation matrix.     

羟基系列卟啉对三聚氰胺的检测研究

研究了四苯基卟啉(TPP)及5种羟基系列卟啉对三聚氰胺的检测,结果表明,TPP及羟基系列卟啉可以用来检测三聚氰胺,三聚氰胺与卟啉发生作用,导致其soret带特征峰强度的变化,其中邻二羟基卟啉对三聚氰胺的检测效果最好,检测限为0.2μg/L,摩尔吸光系数ε为0.6×106L·mol-1.cm-1。并对其作用机理进行了简要分析。     

Cellular automata models of tumour natural shrinkage

In this paper we present three dimensional cellular automata models for tumour growth, with a focus on the tumour’s natural shrinkage caused by the removal of the dead cells’ mortal remains. The significance of this phenomenon for the resulting volume of the in silico tumour is shown. Two algorithms are presented, one using the chain shifting approach for tumour expansion and shrinkage and another improving the performance of the chain shifting approach. Simulations are validated against the experimental results.     

Benzin

Ohne Zusammenfassung     

Simultaneous electron capture and target ion excitation in collisions of C4+ and N5+ on He

Cross sections for simultaneous electron capture and target ion excitation have been measured for impact of slow He-like C⁴⁺ and N⁵⁺ ions on He. The energy of the primary ion beams has been varied over more than two orders of magnitude: 0.05–7 keV/amu. The results are discussed on basis of a slightly modified version of the dynamic classical over-barrier model for multiple electron capture. The differences in the energy dependences of the experimental results of C⁴⁺ and N⁵⁺ — He can be explained qualitatively by assuming that for N⁵⁺ binding energy sharing between the two participating electrons is of importance, particularly at the lower impact energies.     

单质碘掺杂纳米TiO2光催化剂的制备及性能

以钛酸四异丙酯和单质碘为起始原料,用改进的溶胶-凝胶法制备了掺碘的纳米TiO2的前驱体,经500 ℃煅烧得到棕黄色TiO2/I2纳米粉末.采用X射线衍射(XRD),紫外-可见(UV-Vis)漫反射光谱,透射电镜(TEM)等手段对TiO2/I2粉末进行了表征,并研究了其光催化性能.结果表明,掺杂的碘存在于TiO2内部纳米孔洞中,不会因为高温而被氧化;光催化降解甲基橙反应是一级反应;TiO2掺杂碘单质后对光响应波长拓展至可见光范围,对甲基橙的降解效率可提高15%以上.     

用同步辐射X射线衍射技术分析GaN/Si外延膜的结构与应变

选用有AlN和AlGaN缓冲层的GaN/Si作为测试样品,采用同步辐射X射线衍射(SRXRD)技术对样品外延膜(GaN)的几何结构、晶格常量及其应变进行了分析.结果表明,同步辐射X射线衍射实验可以作为一种有效的技术手段,测试固体结构及应变.