Effect of storage temperature on phenolics stability in hawthorn (Crataegus pinnatifida var. major) fruits and a hawthorn drink

The stability of five major phenolics, namely (−)-epicatechin (EC), procyanidin B₂ (PC-B₂), chlorogenic acid (ChA), hyperoside (HP) and isoquercitrin (IQ), in hawthorn fruits and a canned hawthorn drink were evaluated during 6 months of storage in the dark at three different temperatures (4, 23 and 40 °C). HPLC with a diode-array detector was used to determine the contents of the individual compounds. The results showed that the studied phenolics in the hawthorn fruits and the drink were both stable at 4 °C and relatively unstable at 23 and 40 °C with varied extents of degradation. At room temperature (23 °C), marked degradations of EC and PC-B₂ were observed in both the fruits and the drink with around 50% and 30% decrease after a 6-month storage, respectively. A more significant decrease of the phenolics was observed at 40 °C, especially for EC and PC-B₂, which were almost completely degraded after a 6-month storage. HP, IQ and ChA were relatively stable at 23 °C, but unstable at 40 °C. Therefore, low-temperature storage is recommended for maintaining the quality and efficacy of hawthorn fruits and its preparations.     

Existence, uniqueness and stability of the equilibrium points of a SHARON bioreactor model

This paper addresses the dynamics of a SHARON reactor, a promising technology for ammonium removal from concentrated wastewater streams. The contraction mapping theorem is used to determine which operating conditions of a SHARON reactor with pH-control result in a unique equilibrium state. However, this approach only identifies the case of very large dilution rates, in practice corresponding with complete biomass wash-out, i.e. with complete loss of biological activity. Practical operation of a SHARON reactor aims at reaching ammonium conversion to nitrite. To identify such interesting operating points, the equilibrium points are subsequently calculated directly in terms of input variables for a simplified SHARON reactor model. The stability of the obtained equilibrium points is assessed and the corresponding phase portraits are analyzed. The influence of slightly varying parameter and input values is investigated as well.     

提高连铸浊环水水质浅析

介绍了太钢板坯连铸水处理系统的工艺流程，分析了连铸浊环水水质存在的问题。通过对冷却塔部分、铁皮坑、水泵调速等改造，以及选用新的水质稳定剂，使水质明显好转。     

Computation of Bearing Capacity Factor Nγ?Terzaghi’s Mechanism

A procedure based on K?tter’s equation is developed for the evaluation of bearing capacity factor Nγ with Terzaghi’s mechanism. Application of K?tter’s equation makes the analysis statically determinate, in which the unique failure surface is identified using force equilibrium conditions. The computed Nγ values are found to be higher than Terzaghi’s value in the range 0.25–20%, with a diverging trend for higher values of angle of soil internal friction. A fairly good agreement is observed with other solutions which are based on finite difference coupled with associated flow rule, limit analysis, and limit equilibrium. Finally, the comparison with available experimental results vis-à-vis other solutions shows that, computed Nγ values are capable of making a reasonably good prediction.     

Stability analysis of network-based cooperative resource allocation strategies

Resource allocation involves deciding how to divide a resource of limited availability among multiple demands in a way that optimizes current objectives. In this brief paper we focus on one type of distributed resource allocation problem where via an imperfect communication network multiple processors can share the load presented by multiple task types. We introduce asynchronous “cooperative” resource allocation strategies, and show that they lead to a bounded cumulative demand.     

Nonpathological Lyapunov functions and discontinuous Carathéodory systems

Differential equations with discontinuous right-hand side and solutions intended in Carathéodory sense are considered. For these equations, sufficient conditions which guarantee both Lyapunov stability and asymptotic stability in terms of nonsmooth Lyapunov functions are given. An invariance principle is also proven.     

Limited reinforced space in segmental retaining walls

Current design of geosynthetic reinforced segmental retaining walls considers an a priori limitless length for reinforcement installation. Such length is typically 0.5–0.7 times the height of the wall. However, often there are constraints on such space; e.g., bedrock formation located at a small distance behind the facing. The objective of this note is to introduce a procedure for assessing the required long-term strength of the reinforcement while considering its limited length. Predictions by a conventional slope stability analysis were first checked against a continuum-mechanics based numerical analysis. Upon obtaining good agreement, a design chart was developed. The chart enables the determination of the reduction in the lateral earth pressure coefficient due to the constrained space. The revised earth pressure coefficient can be used with current analytical methods to account for the limited space. The results appear to be valid for conventional walls retaining a limited volume of soil. Comparison with limited experimental results for unreinforced backfill shows reasonably good agreement.     

Stability of Periodically Unsteady Axisymmetric Jet

To date, the majority of studies on stability of axisymmetric jets have been completed under the assumption of steady mean flow. Yet, many of the natural and man-made flows that are modeled by these jets can have an inherent unsteadiness; the effects of which on the stability and transition have not been determined. Moreover, controlled unsteadiness can be used to control stability and possibly the transition to turbulence. In this note, the effects of periodic variations of the mean flow on the stability of axisymmetric jets are examined. The problem is treated analytically. The results show that the governing equations and dispersion relation for the unsteady jet can be reduced to those governing the steady jet with a time transformation. It is shown that the periodic variations in the mean flow cause amplitude and phase modulations of the unstable modes. The implications of the modulations on the subsequent transition stages are discussed.     

谷氨酰胺(Gln)活性肽营养液的研究进展

对G1n小肽在氨基酸营养液中的使用以及G1n小肽的稳定性和代谢机制进行了论述。G1n是一种“条件必需氨基酸”，但Cln的水溶液不稳定，因而在氨基酸输液或氨基酸营养被中，用G1n小肽代替G1n单体使用。G1n小肽含有取代的α—NH2，使Cln小肽的稳定性大大增加。