This article deals with the biopic dedicated to Stefan Zweig produced and shot in 2016 by Maria Schrader and entitled Vor der Morgenröte, in English Farewell to Europe. The five chapters of the movie ...concentrate on the final part of Zweig’s life, culminating in his suicide, and they are read as a Stationendrama, or in relation to the impossibility of salvation for exile.
•Two-dimensional ferromagnetic liquid flow over a flat elastic sheet with the magnetic dipole effect is considered.•The Buongiorno model has been used to incorporate Brownian movement and ...thermophoresis effects.•Numerical solution is obtained using Runge–Kutta–Fehlberg 45 method by adopting Shooting technique.•Convective boundary condition has tendency to improve the heat transfer feature of liquid in presence of Stefan blowing condition.
The study is achieved to explore the novel of a two-dimensional ferromagnetic fluid flow over a flat elastic sheet with the magnetic dipole effect. The flow design was chosen because it is often used in engineering and bioengineering applications including magnetic drug targeting systems. The Buongiorno model has been used to incorporate Brownian movement and thermophoresis effects. Further, Stefan blowing effect and convective boundary constraint is taken in to the account. The governing expressions for assumed flow are reduced to ordinary differential equations by opting suitable similarity variables. The reduced equations are solved using Runge–Kutta–Fehlberg 45 method by adopting Shooting technique. The attained numerical outcomes are then illustrated graphically . Result reveals that, upsurge in values of thermophoresis and Brownian motion parameters improves the thermal gradient and the fluid shows high heat transfer in existence of Stefan blowing condition. Convective boundary condition has tendency to improve the heat transfer feature of liquid in presence of Stefan blowing condition. Further, the justification of current outcomes is accomplished by developing comparison with available published work.
The ultimate goal of biological super-resolution fluorescence microscopy is to provide three-dimensional resolution at the size scale of a fluorescent marker. Here we show that by localizing ...individual switchable fluorophores with a probing donut-shaped excitation beam, MINFLUX nanoscopy can provide resolutions in the range of 1 to 3 nm for structures in fixed and living cells. This progress has been facilitated by approaching each fluorophore iteratively with the probing-donut minimum, making the resolution essentially uniform and isotropic over scalable fields of view. MINFLUX imaging of nuclear pore complexes of a mammalian cell shows that this true nanometer-scale resolution is obtained in three dimensions and in two color channels. Relying on fewer detected photons than standard camera-based localization, MINFLUX nanoscopy is poised to open a new chapter in the imaging of protein complexes and distributions in fixed and living cells.
Both experimental investigation and mathematical modeling have been combined to clarify the influence of membrane properties, temperature, electrolyte concentration, and current density on membrane ...resistance of Nafion 117 in concentrated lye solutions. The ionic resistance was measured with and without membrane using four electrodes for 15 wt% and 32 wt% sodium hydroxide, temperatures up to 90 °C, and current densities up to 25 kA/m2. The results from the measurement using Direct Current (DC) method as well as Electrochemical Impedance Spectroscopy (EIS) method indicate that membrane resistance is a function of temperature and lye concentration but is independent of current density. A mathematical model based on the Maxwell-Stefan approach has been developed to predict the ionic membrane resistance, and the model has been validated using the measured experimental data. A more suitable semi-empirical correlation for Maxwell-Stefan diffusivities is proposed by replacing the expressions for binary diffusivities based on infinite dilution with the concentration-dependent binary diffusivities. The new proposed correlation performs better in the model validation with the experimental data than the expressions using infinite dilution diffusivities.
•The ionic membrane resistance of Nafion 117 is measured as a function of temperature, concentration, and current density.•A Maxwell-Stefan model is developed, and the model is validated with the measured resistance.•A more suitable semi-empirical correlation for Maxwell-Stefan diffusivities is proposed.•Both the model and the experiment show that membrane resistance is independent of current density.
We study a non-classical one phase Stefan problem with a particular control function which depends on the evolution of the temperature at the fixed face x=0 and, we assume a Neumann boundary ...condition and an over specified Robin condition at the fixed face. Under certain restrictions on the data an explicit similarity type solution is given. Moreover, we determine the free boundary and one unknown thermal coefficient, or two unknown thermal coefficients depending on whether the direct or inverse Stefan problem is considered.
Improving the removal effect of selenium in wet flue gas desulfurization system is a key way to reduce the emission of selenium pollutants from coal-fired power plants. In order to clarify the ...removal mechanism of selenium pollutants in the desulfurization tower, it is necessary to obtain accurate selenium gas-phase diffusion coefficient. In this paper, molecular dynamics simulations were used to carry out theoretical calculations of gas-phase diffusion coefficients of SeO2 (the main form of selenium in coal combustion flue gas). The gas-phase diffusion coefficients of SeO2 in the range of 393 K–433 K were measured by a self-developed heavy metal gas diffusion coefficient testing device to verify the accuracy of the molecular dynamics calculations. Furthermore, the calculated gas-phase diffusion coefficients of SeO2 under typical binary and ternary components were obtained by correcting on the basis of Fuller's formula. Finally, a single-droplet absorption model for SeO2 was constructed and experiments were carried out to compare the effect of the gas-phase diffusion coefficient on the accuracy of the model calculations. The error of the model calculations was reduced from 8.09 % to 1.96 % after the correction. In this study, the gas-phase diffusion coefficient of SeO2 in the low-temperature range of coal-fired flue gas was obtained. This study can provide basic data for the development of selenium migration mechanism and control technology.
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•SeO2 gas-phase diffusion coefficient (Dg,SeO2) was obtained by molecular dynamics.•Experiments were conducted to measure and verify the theory-obtained Dg,SeO2.•A formula for calculating Dg,SeO2 was proposed and the error was within 9.58 %.•The Dg,SeO2 was applied in a single droplet model to improve its accuracy.
The Maxwell–Stefan (M–S) formulation for binary mixture diffusion in
micro-porous materials such as zeolites, metal organic frameworks (MOFs), and covalent organic frameworks (COFs), that have pore ...sizes typically smaller than 2
nm, is formulated in a manner that is consistent with corresponding description for
meso-porous systems. The M–S equations are set up in terms of species concentrations,
c
i
, defined in terms of accessible pore volume space. Molecular dynamics simulations were carried out to determine the exchange coefficients
Đ
12
for a large variety of binary mixtures in zeolites (MFI, AFI, BEA, FAU, LTA, CHA, and DDR), MOFs (CuBTC, IRMOF-1, Zn(bdc)dabco, Co(bdc)dabco, MIL-47, Co-FA, Mn-FA, and Zn(tbip)), COFs (COF-102, COF-103, and COF-108), and cylindrical silica pores of varying diameters. The exchange coefficients
Đ
12
in all structures were found to be related by a constant factor,
F, with the corresponding M–S diffusivity for binary
fluid mixture,
Đ
12
,
fl
, at the same total mixture concentration,
c
t
, as within the pores. The factor
F is primarily dictated by the degree of confinement of the guest molecules within the channels, defined as the ratio of the characteristic sizes of the guest molecules to that of the host channels. For
meso-porous cylindrical silica pores:
F=1, and
Đ
12
=
Đ
12
,
fl
. For CuBTC, MIL-47, IRMOF-1, and COFs, that have structures with a high fractional open space and channel dimensions of 0.8–1.85
nm, the factor
F is found to be in the range 0.55–0.85. For structures such as MFI, BEA, Co-FA, Mn-FA, and Zn(tbip) that have smaller fractional open space, and channels smaller than 0.6
nm, the factor
F has values <0.2. The major conclusion of this study is that fluid mixture diffusivity
Đ
12
,
fl
provides a good starting point for an engineering estimate of the exchange coefficient
Đ
12
in porous materials.
•A novel analytical model for multi-component drop evaporation is proposed.•The model solves the Stefan–Maxwell equations under steady-state conditions.•The model predictions are compared with the ...results from Fick’s law based models.•The effect of non-isothermal conditions are considered in a simplified way.•The Fick’s law based models generally under-predict the total evaporation rate.
A novel evaporation model for multi-component spherical drop has been developed by analytically solving the Stefan–Maxwell equations under spherical symmetry assumptions. The evaporation rate predicted by the new model is compared with the predictions obtained by previous models based on Fick’s law approximation, under steady-state isothermal conditions for a wide range of gas and drop temperatures and compositions. The effect of non-isothermal conditions are considered in a simplified way, through the effect of temperature on the reference value of gas density and mass diffusion coefficients. The Fick’s law based models are found to generally under-predict the total evaporation rate, particularly at higher evaporation rate conditions.
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