Thiol‐ene photopolymerization for efficient curing of vinyl esters

Monomers for radical photopolymerization based on vinyl esters (VEs) have recently been identified as suitable alternatives to (meth)acrylates on account of their low irritancy and cytotoxicity. The drawback of most VEs with abstractable hydrogens is their relatively low reactivity compared with (meth)acrylates. Within this article, we proved by photo‐differential scanning calorimetry measurements and real‐time Fourier transform infrared spectroscopy that the thiol‐ene concept is able to improve the photoreactivity of these VEs to a large extent to a level between those of acrylates and methacrylates. Other VEs have now a reactivity of at least the level of similar acrylates. Mechanical properties as determined by Dynamic Mechanical Analysis and Charpy impact tests showed significant toughening of these materials. Furthermore, we were able to confirm low toxicity of all components by osteoblast cell culture experiments. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Scheduling periodic customer visits for a traveling salesperson

The problem considered in this paper deals with determining daily routes for a traveling salesperson who provides customers in Upper Austria with product range information of a large, global food wholesaler. Each customer has to be visited at least once a year, with some customers requiring up to one visit per month. Further, some customers may not be visited each day of the week. Our decision support system uses a commercial GIS software to extract customer data for input into the optimization procedure and to visualize the results obtained by the algorithm. The optimization approach is based on the variable neighborhood search algorithm which assigns customers to days and determines routes for the salesperson for each day with the primary objective to minimize the total travel time of the salesperson. Another objective studied is to minimize the number of days needed by the salesperson to visit all customers in a given month. Further we analyze the effects of changes in the business environment like increases in the amount or flexibility of the salesperson’s working time and variations in the possible days for customer visits. Finally, we enrich the objective function by considering periodicity requirements for customer visits. Specifically, we penalize irregular schedules, where the time between two successive customer visits varies.     

脉管制冷机直流机理研究和抑制方法探讨

双向进气脉管制冷机中存在的直流流动不仅增加了冷端换热器的负载 ,降低了脉管制冷机的性能 ,而且还是引起脉管制冷机制冷温度不稳定的一个重要原因。文中从流体网络理论出发 ,分析了直流产生的机理 ,对目前各种抑制方法进行了探讨 ,指出了进一步研究的方向。     

Optical biosensor for pharmaceuticals, antibiotics, hormones, endocrine disrupting chemicals and pesticides in water: Assay optimization process for estrone as example

Certain contaminants at trace concentrations in surface waters can have dramatic effects on the hormonal system of organisms in the aquatic environment. Therefore, immunoanalytical methods at a very low limit of detection (LOD) and a low limit of quantification (LOQ) are becoming more and more important for environmental analysis and especially for monitoring drinking water quality. Environmental monitoring of antibiotics, hormones, endocrine disrupting chemicals, and pesticides in real water samples (e.g. surface, ground or drinking water) with difficult matrices places high demands on chemical analysis. Biosensors have suitable characteristics such as efficiency in allowing very fast, sensitive, and cost-effective detection. Here we describe an assay optimization process with a fully automated immunoassay for estrone which resulted in a LOD below 0.20 ng L⁻¹ and a LOQ below 1.40 ng L⁻¹. In contrast to common analytical methods such as GC-MS or HPLC-MS, the biosensor used requires no sample pre-treatment and pre-concentration. The very low validation parameters for estrone are the result of the continuous optimization of the immunoassay. The basis of our sensitive assay is the antibody with a high affinity constant towards estrone. During the optimization process, we reduced the amount of antibody per sample and improved the chip surface modification. Finally, this proceeding led to a calibration routine with an amount of antibody of only 3.0 ng per sample (sample volume: 1.0 mL). The reduction of the amount of antibody per sample results in better validation parameters (LOD, LOQ, and IC₅₀), but this reduction leads to the current device-related limitation of the River Analyser (RIANA).For some endocrine disrupting compounds, no effect levels (NOELs) in the lower nanogram per liter range are reported. This defines the challenge, which analytical methods have to compete with and our RIANA instrument with its improved sensitivity for the detection of a single hormone in the lower nanogram per liter range is a powerful tool in aquatic analytics in addition to the common analytical methods.     

Double indication in catalytic-kinetic analysis: simultaneous photometric and thermometric indication of the iodine-azide reaction in closed and flow systems

The iodine—azide reaction catalyzed by sulphur-containing compounds is followed simultaneously by optical and thermometric measurements in closed and flowing systems. In the closed system, thiosulphate can be determined in the range 32.4–324 μg ml^-1, by observing the turbidity caused by the nitrogen formed during the reaction and the temperature changes. With the flow apparatus, thiosulphate can be determined in the range 112–1120 μg ml^-1 by continuously mixing the sample and reagent solutions. H₂S in nitrogen 5–100 ppm) is measured by sweeping the gas into the reaction Cuvette. In a third flow procedure, H₂S is liberated continuously from sodium sulphide solutions (0.1–10 μg S^2- ml^-1) by ascorbic acid, and swept to the measuring cuvette with nitrogen.     

热耦合型二级高频脉冲管制冷机实验研究

降低制冷温度至4 K温区是高频脉冲管制冷机的最新发展要求。本文介绍了一套热耦合型二级高频脉冲管制冷机的性能特性,它可以达到低于15 K以下的最低温度,是目前报道的高频二级脉冲管制冷机能获得的最低温度．通过对制冷机一级预冷、二级输入功率、二级冷量、室温条件等影响的分析,从实验角度揭示了该二级制冷系统的复杂影响,为进一步的深入分析和改进提供了基础。     

Tests of quantum electrodynamics using ion traps

Experiments in ion traps on the g factors for the free and the bound electron in low-Z, hydrogen-like ions have provided the most accurate tests of quantum-electrodynamics calculations. Moreover they have been used to determine new and precise values for fundamental constants. Extensions to more stringent tests using ions of higher values of the nuclear charge Z are on the way. Also other QED tests such as Lamb shifts or hyperfine structures in H-like ions using traps will be feasible in the near future. The tests in bound systems, however, will be limited by nuclear structure effects which are difficult to calculate. Assuming the QED calculations as correct, the experimental results may be used to determine nuclear contributions and thus support nuclear models. Contribution presented at the TCP06, Vancouver Island, 2006.     

Contributions to the Experimental Investigation of the Nascent Polymerisation of Ethylene on Supported Catalysts, 2

A series of experiments in a novel quench flow reactor was used to study the influence of the means of adding TEA to the catalyst, the reaction temperature and the hydrogen concentration on the kinetics and morphology of the nascent phase of the polymerisation of ethylene in heptane slurry. It was shown that regardless of the way in which the alkyl was added, an extremely rapid reaction rate was observed for the first few fractions of a second, but that precontacting the catalyst and the TEA cocatalyst led to a slightly higher initial rate. On the other hand, the nascent morphology of the particle/support complex was strongly influenced by the means of adding the alkyl, with precontacting of the two components leading to a better defined product. The influence of the temperature was found to be less significant; however, this was attributed to the particular catalyst.