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排序方式: 共有261条查询结果,搜索用时 19 毫秒
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2.
Here, we report on the application of corroles as analytically active compounds in liquid membrane electrodes (ISE) that are sensitive towards salicylic acid and salicylate.The potentiometric signals generated by corrole-incorporated ISEs strongly depend on the pH of the aqueous sample solution and the membrane composition, such as the presence of lipophilic sites. Corrole incorporating ISEs are characterised by a low detection limit (4.0 × 10−5 M) and a wide linear range (4.0 × 10−5 to 5.3 × 10−3 M). Also, they are free from interference versus other organic anions.The mechanism of the generation of the potentiometric signals of corrole incorporating ISEs in the presence of salicylate anion, as well salicylic acid, will be discussed. 相似文献
3.
The general objective of this paper is to investigate the separation, with microfluidics, of the components of a ternary mixture, when using vacuum or purge gas pervaporation. The ternary mixture considered is a mixture of methanol (MeOH), water (H2O) and hydrogen peroxide (H2O2). In a previous work (Ziemecka in Lab Chip 15:504–511, 2015), we presented the proof of concept of a microfluidic device, which was able to partially separate MeOH from the other components of such a mixture, by using vacuum pervaporation. Here, our goal is to optimize the operation of this device, by considering vacuum pervaporation, but also purge gas pervaporation. First, we provide a mathematical model of the device. This model is used to discuss the influence of the operating parameters on the device operation. To apply this model to the considered mixture, we determined the MeOH and H2O permeability coefficients of PDMS membranes prepared from different concentrations of the curing agent. The model is then successfully compared to experimental data. The model and the experiments show that high efficiencies can be reached for both vacuum and purge gas pervaporation, provided a fine-tuning of the operating parameters. For instance, a good efficiency of the vacuum pervaporation is reached at high temperature and low pressure. For purge gas pervaporation, it is reached for low temperature and high pressure. 相似文献
4.
Iwona Pokorska 《Structural and Multidisciplinary Optimization》2008,37(1):77-89
The purpose of this paper is to analyze the sensitivity problems in metal forming of rigid-visco-poroplastic materials. A
repressing powder forging process is analyzed. Parameter sensitivity, material derivative, and control volume approaches to
shape sensitivity analysis are presented, analyzed, and compared. Discretization of the continuum expressions is presented.
The numerical solutions for parameter sensitivity in forging problems have been described. Numerical examples concerning simple
compression test of cylindrical porous specimen are presented. 相似文献
5.
6.
Iwona Jóźwik Agata Strojny‐Nędza Marcin Chmielewski Katarzyna Pietrzak Łukasz Kurpaska Szymon Nosewicz 《Microscopy research and technique》2018,81(5):502-508
The performance of the present‐day scanning electron microscopy (SEM) extends far beyond delivering electronic images of the surface topography. Oxide dispersion strengthened (ODS) steel is on of the most promising materials for the future nuclear fusion reactor because of its good radiation resistance, and higher operation temperature up to 750°C. The microstructure of ODS should not exceed tens of nm, therefore there is a strong need in a fast and reliable technique for their characterization. In this work, the results of low‐kV SEM characterization of nanoprecipitates formed in the ODS matrix are presented. Application of highly sensitive photo‐diode BSE detector in SEM imaging allowed for the registration of single nm‐sized precipitates in the vicinity of the ODS alloys. The composition of the precipitates has been confirmed by TEM‐EDS. 相似文献
7.
Katarzyna Grzybowska Zaneta Wojnarowska Andrzej Grzybowski Marian Paluch Juan M. Giussi M. Susana Cortizo Iwona Blaszczyk-Lezak Carmen Mijangos 《Polymer》2014
In this paper, dielectric and calorimetric studies of the small-molecule glass former allyl acetoacetate monomers as well as its newly synthetized homopolymer and copolymers with different styrene composition were performed in both the liquid and glassy states. The molecular dynamics studies by the broadband dielectric spectroscopy and the stochastic temperature modulated differential scanning calorimetry enabled us to explore relaxation processes of examined materials in the wide frequency range. We found that the copolymers reveal two co-existing glass transitions characterized by the glass transition temperatures, which are very close to those of the corresponding homopolymers. These results suggest that the copolymers exhibited some sequences of acetoacetate units with a microphase-separated morphology in agreement with the value of reactivity ratio previously determined. We investigated effects of copolymerization compositions on the glass transition temperature, the isobaric fragility index, the dielectric and calorimetric intensity, and the dynamic heterogeneity on the glass transitions of the materials. 相似文献
8.
Iwona Zarzyka‐Niemiec 《Polymer International》2009,58(4):388-395
BACKGROUND: The work reported aimed at obtaining hydroxyalkoxy derivatives containing oxalamidoester groups starting from oxamic acid (OA) substrate. These derivatives were then used for the synthesis of polyurethane foams. RESULTS: The hydroxyalkoxy derivatives were obtained by reaction of OA with 6 to 15 molar excess of ethylene carbonate (1,3‐dioxolane‐2‐one) or propylene carbonate (4‐methyl‐1,3‐dioxolane‐2‐one). The products obtained have good thermal stability and possess suitable physical properties for use as substrates for foamed polyurethanes. CONCLUSION: The rigid polyurethane foams obtained from the hydroxyalkoxy derivatives of OA possess enhanced thermal stability and good mechanical properties in comparison with traditional polyurethane foams. Copyright © 2009 Society of Chemical Industry 相似文献
9.
Iwona Cieślik 《Acta Informatica》2005,42(1):1-20
The problem of on-line coloring of an arbitrary graphs is known to be hard. Here we consider the problem of on-line coloring
in the simplified situation where the input graph is KKs,t-free. We show that the on-line coloring algorithm with the First Fit strategy of proposed by Capponi and Pilotto in [1] is the best one for KK1,t-free graphs (t≥3). A.Capponi and C.Pilotto have shown that this algorithm achieves a competitive ratio of t−1 while we show that it is the best possible. However for the family of KKs,t-free graphs (s≥2, t≥2) there exists no on-line coloring algorithm with a competitive function. The problem of an on-line cliques covering for
these families is hard. There exists no on-line cliques covering algorithm with a competitive function for the family of KKs,t-free graphs (s≥ 1, t≥3). The additional assumption that the input graph is given in a connected way does not help a lot and does not change our
results described above. 相似文献
10.
Iwona Skalna 《Reliable Computing》2006,12(2):107-120
Consider the systems of linear interval equations whose coefficients are linear functions of interval parameters. Such systems,
called parametrized systems of linear interval equations, are encountered in many practical problems, e.g in electrical engineering
and structure mechanics. A direct method for computing a tight enclosure for the solution set is proposed in this paper. It
is proved that for systems with real matrix and interval right-hand vector the method generates the hull of the solution set.
For such systems an explicit formula for the hull is also given. Finally some numerical examples are provided to demonstrate
the usefulness of the method in structure mechanics. 相似文献