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2.
The trench on a printed circuit board was reconstructed to fabricate a microfluidic framework that allows low-cost production for small quantities and integration with multifunctional elements. An on-chip electrolyte regulator was thus proposed on this platform to analyze diffusion properties in laminar flow. A numerical model was developed, highlighting the interplay between the electrolyte migration and hydrodynamic properties. Solutions with dissolved sodium chloride were simulated and experimentally tested for the regulation of electrical conductivity under the guidance of the normalized Nernst-Planck equation. The diffusion mechanism and the resulting concentration field were demonstrated in detail. This approach provides a satisfactory manufacturing method and a useful tool for integrated microfluidic systems. 相似文献
3.
《Physics letters. A》2019,383(22):2594-2603
In this work, we address the systematic biases and random errors stemming from finite step sizes encountered in diffusion simulations. We introduce the Effective Geometry Monte Carlo (EG-MC) simulation algorithm which modifies the geometry of the receiver. We motivate our approach in a 1D toy model and then apply our findings to a spherical absorbing receiver in a 3D unbounded environment. We show that with minimal computational cost the impulse response of this receiver can be precisely simulated using EG-MC. Afterwards, we demonstrate the accuracy of our simulations and give tight constraints on the single free parameter in EG-MC. Finally, we comment on the range of applicability of our results. While we present the EG-MC algorithm for the specific case of molecular diffusion, we believe that analogous methods with effective geometry manipulations can be utilized to approach a variety of problems in other branches of physics such as condensed matter physics and cosmological large scale structure simulations. 相似文献
4.
《Physics letters. A》2020,384(21):126426
Using density functional theory combined with a global crystal structure search with the particle swarm optimization method, we propose three stable three-dimensional (3D) metallic RhP structures, namely, the Cmcm (RhP-I), P6/mmm (RhP-II), and P63mc (RhP-III) phases. All these structures are found to be dynamically stable through vibrational normal mode calculations, indicating that they could be successfully synthesized in experiments. We show that the RhP-I phase has a relatively high thermodynamic stability and high mechanical strength in comparison with the others. The RhP-II and RhP-III phases have porous structures which could accommodate small atoms or molecules. However their thermodynamics are poor, especially the RhP-III phase. The RhP-II structure is stable at 500 K, but the RhP-III fails to survive even at the freezing point of water. Importantly, all these materials have one dimensional conducting channels corresponding to ultrahigh Fermi velocities. Moreover, the porous hexagonal RhP-II and III structures exhibit excellent ability to trap lithium, hydrogen, oxygen, and boron atoms. The RhP-II structure could be especially useful for directly dissociating the hydrogen molecule into two atoms without an energy barrier. In the present study, we identify three new metallic structures to the family of RhP structures, and anticipate their potential for technological applications. 相似文献
5.
We study the initial–boundary value problem for a Laplace reaction–diffusion equation. After constructing local solutions by using the theory of abstract degenerate evolution equations of parabolic type, we show asymptotic convergence of bounded global solutions if they exist under the assumption that the reaction function is analytic in neighborhoods of their -limit sets. Reduction of degenerate evolution equation to multivalued evolution equation enables us to use the theory of the infinite-dimensional Łojasiewicz–Simon gradient inequality. 相似文献
6.
《力学快报》2020,10(1):33-37
A mass diffusion model is developed to describe the growth kinetics of Cu_6Sn_5 intermetallic compounds(IMC) in the Cu-Sn-Cu sandwich structure. The proposed model is based on the local interfacial mass conversation law where interfacial Cu/Sn reactions and atomic diffusion are considered. Theoretical analysis shows that the IMC thickness growth is proportional to the square root of the product of the diffusion coefficient and time. The proposed model can explain the polarity effect of electromigration on kinetics of IMC growth where all the parameters have clear physical meaning. The theoretical predictions are compared with experimental results and show reasonable accuracy. 相似文献
7.
8.
《Journal of Saudi Chemical Society》2023,27(3):101645
To study the desorption mechanism of methane in coal by H2O injection and establish the Wiser molecular structure model of bituminous coal, the Grand Canonical Monte Carlo method was used to study the desorption behavior of CH4 in coal with different amounts of H2O injection at molecular scale. The results showed that at 293 K, the maximum adsorption capacity of H2O was about 16 mmol/g, and that of CH4 was about 8 mmol/g, which was about twice that of CH4. This indicates that H2O has a stronger adsorption capacity than CH4. For methane-bearing coal, when the amount of water injected is 100, the average relative concentration of CH4 is 0.5446, and the average relative concentration of CH4 decreases by 33.77% compared to the water content of 20. Under the same time conditions, the root mean square displacement and diffusion coefficient of CH4 decrease with the increase of H2O injection quantity. With the increase of H2O injection, the motion velocity of CH4 in vacuum layer decreased. When water was injected, methane was trapped in the coal by water. The more H2O injected, the more methane trapped in the coal, and the less methane desorption. This research lays a theoretical foundation for further research involving coal-water interaction. 相似文献
9.
Xiao-Yu Li Dr. Tao Wang Yu-Chen Cai Zhao-Dong Meng Jing-Wen Nan Dr. Jin-Yu Ye Prof. Dr. Jun Yi Prof. Dr. Dong-Ping Zhan Prof. Dr. Na Tian Prof. Dr. Zhi-You Zhou Prof. Dr. Shi-Gang Sun 《Angewandte Chemie (International ed. in English)》2023,62(14):e202218669
Proton transfer is crucial for electrocatalysis. Accumulating cations at electrochemical interfaces can alter the proton transfer rate and then tune electrocatalytic performance. However, the mechanism for regulating proton transfer remains ambiguous. Here, we quantify the cation effect on proton diffusion in solution by hydrogen evolution on microelectrodes, revealing the rate can be suppressed by more than 10 times. Different from the prevalent opinions that proton transport is slowed down by modified electric field, we found water structure imposes a more evident effect on kinetics. FTIR test and path integral molecular dynamics simulation indicate that proton prefers to wander within the hydration shell of cations rather than to hop rapidly along water wires. Low connectivity of water networks disrupted by cations corrupts the fast-moving path in bulk water. This study highlights the promising way for regulating proton kinetics via a modified water structure. 相似文献
10.
Ternary mutual diffusion coefficients (D11, D22, D12 and D21) measured by the Taylor dispersion method are reported for aqueous solutions of {levodopa (l-dopa) + β-cyclodextrin (β-CD)} solutions at T = 298.15 K and concentrations up to 0.007 mol · dm−3. Significant effects on the diffusion were observed, suggesting interactions between this carbohydrate and l-dopa. Support for this came from 1H NMR spectroscopy, which shows that these effects are due to formation of 1:1 (β-CD:l-dopa) complexes. 相似文献