Nonlinear frequency response functions of a chromatographic column—A critical evaluation of their potential for estimation of single solute adsorption isotherms

Nonlinear frequency response analysis is applied to study single component adsorption in chromatographic columns. Single component adsorption isotherms can be estimated from local derivatives of the adsorption isotherm at specified steady-state concentrations, which are obtained from the low frequency asymptotic behavior of the higher order frequency response functions (FRFs) of a chromatographic column. The functions relevant for the estimation of adsorption isotherms are the phases and the first derivatives of these FRFs. These functions (up to the third order) are analyzed for different types of adsorption isotherm models, different isotherm parameters, steady-state concentrations and numbers of theoretical plates of the chromatographic column. Based on this analysis, some unified characteristics of these functions are observed, which can be used for critical evaluation of the method and to design efficient experimental procedures for its application. Advantages and limitations of this method are discussed.     

“Herzallerliebstes helenchen”. Mileva Einsteins briefe an helene savić

Ohne Zusammenfassung Wir danken Dr. Aleksandar Petrović (Belgrad) für den Hinweis auf das hier vorgestellte Buch.     

Feasibility analysis for robustness quantification by symbolic model checking

We propose and investigate a robustness evaluation procedure for sequential circuits subject to particle strikes inducing bit-flips in memory elements. We define a general fault model, a parametric reparation model and quantitative measures reflecting the robustness capability of the circuit with respect to these fault and reparation models. We provide algorithms to compute these metrics and show how they can be interpreted in order to better understand the robustness capability of several circuits (a simple circuit coming from the VIS distribution, circuits from the itc-99 benchmarks and a CAN-Bus interface).     

Formation of Al2O3 Scales on Single-Phase RuAl Produced by Reactive Sintering

The oxidation behavior of single-phase RuAl produced by powder metallurgy combined with arc melting was investigated. Oxidation was conducted at 1000°C; oxide scale growth and phase formation were studied using scanning-electron microscopy (SEM) and x-ray diffraction (XRD). A dense protective scale with an Al–depleted sublayer was formed during oxidation. The oxide scale is the stable -Al₂O₃. The oxide-scale morphology shows the presence of whiskers, with a needle-like form, which suggests that the growth of the oxide scale is produced by outward diffusion of Al. At the beginning, oxidation follows a parabolic law, but, after 100 hr of oxidation; the growth rate is slower than expected from a parabolic law.     

Topological Resonance Energies of Conjugated Structures

The graph-theoretical backbone of the topological resonance energy (TRE) concept is outlined and the connection with the Dewar resonance energy (DRE) approach is described. It appears that the TRE is not a new aromaticity index, but an optimal DRE-like quantity of great practical value for understanding and predicting the aromatic stability of conjugated structures. In the TRE concept the most important result is the introduction of the acyclic polynomial which closely approximates the acyclic-polyene reference structure. The rules for the construction of the acyclic (reference) polynomial are presented. Application of TRE to monocyclic systems, to polycyclic molecules and their radicals and ions, to homoaromatic systems, and to excited states is discussed. In most cases the agreement between the theory and experimental findings is good. However, in some examples the predictions appear to be inconsistent with reported data. The reasons for the occasional anomalies in the TRE are investigated. In addition, the problem of normalization of the TRE is considered.     

大尺寸S型焊接金属波纹管刚度及薄板焊接接头应力分析

建立大尺寸S型焊接金属波纹管非对称截面有限元模型,采用ANSYS对其在弹性范围内的轴向刚度进行模拟计算,并与试验结果及经验公式计算结果进行对比。模拟结果与试验结果及经验计算值非常接近,说明可以用AN-SYS来模拟计算刚度,从而解决了大尺寸焊接金属波纹管刚度难以测量的问题。波纹管膜片的最大应力集中在内圆焊接处,可通过改善内圆焊接处的应力状况来提高波纹管的使用寿命。对薄板不同大小焊接接头的应力进行分析,结果表明,当焊接接头的截面半径为板厚的1.5倍时,焊接接头处应力值比较小,不易发生应力集中和失弹现象。     

Influence of 1-Methylcyclopropene (1-MCP) on Postharvest Storage Quality in Green Bell Pepper Fruit

The goal of this research was to evaluate the efficiency of 1-methylcyclopropene (1-MCP) on maintaining the quality parameters and antioxidant activity of bell pepper cv. Selika (an original red cultivar) and cv. H1530 (??ever-green?? line) after 18?days storage at 7°C and 3?days at 20°C. Fruits were harvested at green color, from a commercial shade net house in the desert region in Israel. In both cultivars, 600?nL?L^?1 1-MCP reduced weight loss and maintained firmness more than control or 900?nL?L^?1 1-MCP. Overall, 1-MCP treatment had a pronounced effect on delaying ripening processes as shown by inhibiting color changes, decreasing decay, and maintaining quality of non-climacteric green pepper fruit. 1-MCP treatment reduced the lipophilic antioxidant activity of this fruit, but the hydrophilic antioxidant activity remained similar to that observed at harvest.     

A geometric time series model with dependent Bernoulli counting series

A new stationary first‐order integer‐valued autoregressive process with geometric marginal distribution based on the generalized binomial thinning is introduced. The model involves dependent count variables. Some properties of the process are determined. A set of estimators are obtained, and their asymptotic distributions are considered. Some numerical results of the estimates are presented. Possible application of the process is discussed through the real data example.