排序方式: 共有162条查询结果,搜索用时 0 毫秒
21.
Oxygen reduction reaction (ORR) is one of the most technologically relevant reactions. It occurs at the interface of the electrocatalyst and electrolyte, where oxygen reacts with protons and electrons to produce water. Because the electrocatalyst is dispersed on a high surface area support, morphological confinement becomes critical, as it dictates proton and oxygen transport. Furthermore, confinement is induced by ionomer, ionic liquids (ILs), or molecular additives, and their impact on electrocatalyst reactivity and transport properties is currently not well understood. We present an overview of electrostatics and mass transport–induced confinement and zoom in into ILs and molecular additives and try to unravel how local confinement induced by them impacts ORR. 相似文献
22.
Ahmed M. M. Gabr Hoda B. Mabrok Emam A. Abdel-Rahim Mohamed K. El-Bahr Iryna Smetanska 《Natural product research》2018,32(15):1867-1871
Hairy root culture is a promising alternative method for the production of secondary metabolites. In this study, transformed root of Linum usitatissimum was established using Agrobacterium rhizogenes A4 strain from root cultures for lignans, phenolic acids and antioxidant capacity determination. Total lignin content (secoisolariciresinol diglucoside, secoisolariciresinol and matairesinol) was 55.5% higher in transformed root cultures than in the non-transformed root culture. Secoisolariciresinol was detected in higher concentration (2.107 μmol/g DM) in the transformed root culture than non-transformed culture (1.099 μmol/g DM). Secoisolariciresinol diglucoside and matairesinol were exclusively detected in the transformed root culture, but were not found in the non-transformed root culture. The overall production of phenolic acids in transformed roots was approximately 3.5 times higher than that of the corresponding non-transformed culture. Free radical scavenging DPPH˙ and ABTS˙+ assays showed 2.9-fold and 1.76-fold higher anti-oxidant activity in transformed root culture as compared to non-transformed. 相似文献
23.
Iryna Tsimashenka William J. Knottenbelt Peter G. Harrison 《Annals of Operations Research》2016,239(2):569-588
We consider split–merge systems with heterogeneous subtask service times and limited output buffer space in which to hold completed but as yet unmerged subtasks. An important practical problem in such systems is to limit utilisation of the output buffer. This can be achieved by judiciously delaying the processing of subtasks in order to cluster subtask completion times. In this paper we present a methodology to find those deterministic subtask processing delays which minimise any given percentile of the difference in times of appearance of the first and the last subtasks in the output buffer. Technically this is achieved in three main steps: firstly, we define an expression for the distribution of the range of samples drawn from \(n\) independent heterogeneous service time distributions. This is a generalisation of the well-known order statistic result for the distribution of the range of \(n\) samples taken from the same distribution. Secondly, we extend our model to incorporate deterministic delays applied to the processing of subtasks. Finally, we present an optimisation scheme to find that vector of delays which minimises a given percentile of the range of arrival times of subtasks in the output buffer. We show the impact of applying the optimal delays on system stability and task response time. Two case studies illustrate the applicability of our approach. 相似文献
24.
Perepichka II Borozenko K Badia A Bazuin CG 《Journal of the American Chemical Society》2011,133(49):19702-19705
Understanding and controlling the processes in block copolymer (BC) monolayers at the air/water interface during surface area compression is a key issue for producing ultrathin films of predetermined morphology with well-defined order and known dimensions. Langmuir isotherms of nanodot-forming BC monolayers generally display a plateau indicative of a 2D phase transition, which has been the subject of various interpretations in the literature. Here, based on investigations of Langmuir-Blodgett and Langmuir-Schaefer nanodot films of PS-P4VP mixed with 3-n-pentadecylphenol (PDP), we show by atomic force microscopy (AFM) that it involves a change in nanodot packing order (from quasi-hexagonal to quasi-square), argued to be a general phenomenon for nanodot BC monolayers. It is accompanied by system-specific conformational changes (as discussed in previous literature), which, in the present case, implicate PDP alkyl chain ordering, as deduced previously from in situ infrared data and indirectly supported here by AFM imaging. 相似文献
25.
26.
Iryna Egorova Johanna Michor Gerald Teschl 《Proceedings of the American Mathematical Society》2007,135(6):1817-1827
We provide a rigorous treatment of the inverse scattering transform for the entire Toda hierarchy in the case of a quasi-periodic finite-gap background solution.
27.
Iryna Antal Zholt Kormosh Yaroslav Bazel Svitlana Lysenko Natalya Kormosh 《Electroanalysis》2010,22(22):2714-2719
Vitamin B1‐selective electrodes with PVC membrane were developed that contain ion associates of vitamin B1 with an inorganic anion, BiI4?, and an organic anion, brilliant yellow, as electrode‐active substances. The linearity ranges of the electrode function are 1.0×10?5–1.0×10?2 and 1.0×10?4–1.0×10?2 M, the electrode function slopes are 33.0±1.0 and 33.1±1.1 mV decade?1, the detection limits are 5.5×10?6 and 8.3×10?5 M for BiI4? and brilliant yellow respectively. The working range of pH is 5–12. The efficiency of the use of electrodes for the vitamin B1 content control in multivitamin pharmaceutical preparations was shown by direct potentiometry and potentiometric titration methods. 相似文献
28.
Dmytro Kharchenko Vasyl Kharchenko Iryna Lysenko 《Central European Journal of Physics》2011,9(3):698-709
We apply the phase field crystal method for nonequilibrium patterning to stochastic systems with an external source in which
transient dynamics is essential. Considering a prototype model for a one-component periodic system subjected to external influence
kind of irradiation we study properties of pattern selection processes and external noise induced pattern-forming transitions.
These processes are examined by means of the structure function dynamics analysis. Nonequilibrium pattern-forming transitions
are analyzed numerically. 相似文献
29.
Cherenok S Vovk A Muravyova I Shivanyuk A Kukhar V Lipkowski J Kalchenko V 《Organic letters》2006,8(4):549-552
[structure: see text] Chiral calix[4]arene alpha-aminophosphonic acids were obtained through diastereoselective Pudovik-type addition of sodium ethyl phosphites to the chiral calixarene imines, removal of chiral auxiliary groups, and mild dealkylation of phosphonate fragments. The diacids obtained show inhibitory activity toward porcine kidney alkaline phosphatase that depends considerably on the absolute configuration of the alpha-carbon atoms. 相似文献
30.
Garcia Idoia Cortes Kulchytska-Ruchka Iryna Schöps Sebastian 《Numerical Algorithms》2022,91(1):389-412
Numerical Algorithms - This article proposes modifications of the Parareal algorithm for its application to higher index differential algebraic equations (DAEs). It is based on the idea of applying... 相似文献