Microreactors, ultrasonic waves, and alcoholic solvents have been proven to be efficient techniques for CO2 desorption improvement. In the present study, the simultaneous use of all three methods was ...proposed. First, a direct-contact sono-microreactor was designed and employed for CO2 desorption from MEA, DEA, and MDEA aqueous solvents. The effect of temperature, flow rate, microchannel diameter, and ultrasound power were evaluated. Since MDEA indicated the highest desorption rate and the minimum regeneration energy demand, it was chosen for preparing hybrid solvents using methanol and ethanol. Aqueous and alcoholic MDEA solutions in terms of desorption efficiency and regeneration energy requirement were compared. The results demonstrated that MDEA-methanol inside the efficiently designed sono-microreactor could desorb 93.3% of CO2 with regeneration energy of 2.26 MJ/kg CO2, indicating 46.1% energy saving compared to 30 wt % MEA benchmark.
•Utilizing ultrasound-equipped microreactor for CO2 desorption.•Evaluating temperature, solvent flow, microchannel diameter, and ultrasound power.•Simultaneous effect of ultrasound, microreaction and alcoholic solvents on desorption.•High performance of CO2 desorption from MDEA-Methanol.
Atomic-scale characterization and manipulation with scanning probe microscopy rely upon the use of an atomically sharp probe. Here we present automated methods based on machine learning to ...automatically detect and recondition the quality of the probe of a scanning tunneling microscope. As a model system, we employ these techniques on the technologically relevant hydrogen-terminated silicon surface, training the network to recognize abnormalities in the appearance of surface dangling bonds. Of the machine learning methods tested, a convolutional neural network yielded the greatest accuracy, achieving a positive identification of degraded tips in 97% of the test cases. By using multiple points of comparison and majority voting, the accuracy of the method is improved beyond 99%.
Effect of spatially variable magnetic field on ferrofluid flow and heat transfer is investigated. The enclosure is filled with Fe3O4–water nanofluid. Control volume based finite element method ...(CVFEM) is applied to solve the governing equations. The combined effects of ferrohydrodynamic and magnetohydrodynamic have been taken into account. The influences of Magnetic number, Hartmann number, Rayleigh number and nanoparticle volume fraction on the flow and heat transfer characteristics have been examined. Results show that enhancement in heat transfer decrease with increase of Rayleigh number while for two other active parameters different behavior is observed. Also it can be concluded that Nusselt number is an increasing function of Magnetic number, Rayleigh number and nanoparticle volume fraction while it is a decreasing function of Hartmann number.
•Ferrofluid flow and heat transfer in presence of spatially variable magnetic field is studied.•CVFEM is used to solve this problem.•Nu has direct relationship with ϕ, MnF and Ra.•Nu has reverse relationship with Ha.
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The terahertz (THz) absorption features are theoretically investigated in a symmetric one-dimensional photonic crystal hybridized with a vanadium dioxide (VO
2
) phase change material (PCM). VO
2
is ...one of the most prominent PCMs whose conductivity increases three orders of magnitude during its phase transition from a semiconducting monoclinic to a metallic tetragonal structure. Here, we utilize this property of VO
2
to engineer a tunable THz optical device. Our results show that when the VO
2
is in the semiconductor state with low conductivity of 200 S/m, the structure is nearly reflective. However, increasing the VO
2
conductivity continuously to the value of 1.5 × 10
5
S/m increases its metallic level further leading to the perfect absorption of the structure. Further increasing the VO
2
conductivity to the value of 2 × 10
5
S/m reconfigures it to the fully metallic state so that the absorption peak value remains unit as well. In other words, there is a unit contrast in the absorption levels between two semiconductor and metallic states of VO
2
for the proposed structure, which makes it promising for designing tunable nearly reflective and absorbent bifunctionality and optical switching THz devices.
In this research, tetraethyl orthosilicate (TEOS) is used as organosilane to decorate the surface of graphene oxide (GO) nanosheets by SiO2 nanospheres via a facile method. Results of X-ray ...diffraction analysis, Raman spectroscopy, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, and atomic force microscopy reveal that SiO2 nanospheres have covered the surface of GO sheets through covalent bonding and SiO2-GO nanohybrids are successfully synthesized. Further, the effect of incorporating 0.1wt% GO nanosheets and/or SiO2-GO nanohybrids on properties of epoxy coatings is investigated. The results show that the pull-off adhesion strength of epoxy coatings to mild steel substrates and the water contact angle on coatings significantly increase via adding SiO2-GO nanohybrids. The potentiodynamic polarization test, electrochemical impedance spectroscopy (EIS) and salt spray test results demonstrate that corrosion protection performance of epoxy coatings remarkably enhances by embedding well-distributed SiO2-GO nanohybrids compared to GO nanosheets.
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•TEOS is used as an organosilane to prepare SiO2-GO nanohybrids.•SiO2-GO nanohybrids are used as nanofiller in epoxy coatings.•Adhesion and water contact angle of epoxy coating increases by adding SiO2-GO.•Epoxy coatings containing SiO2-GO nanohybrids show superior corrosion protection.•Mechanism of SiO2-GO nanohybrids on properties of epoxy coatings is proposed.
A new analytical method (DTM-Padé) was developed for solving magnetohydrodynamic boundary-layer equations. It was shown that differential transform method (DTM) solutions are only valid for small ...values of independent variable. Therefore the DTM is not applicable for solving MHD boundary-layer equations, because in the boundary-layer problem y→∞. Numerical comparisons between the DTM-Padé and numerical methods (by using a fourth-order Runge–Kutta and shooting method) revealed that the new technique is a powerful method for solving MHD boundary-layer equations.
Improving heat transfer is a critical subject for energy conservation systems which directly affects economic efficiency of these systems. There are active and passive methods which can be employed ...to enhance the rate of heat transfer without reducing the general efficiency of the energy conservation systems. Among these methods, passive techniques are more cost-effective and reliable in comparison with active ones as they have no moving parts. To achieve further improvements in heat transfer performances, some researchers combined passive techniques. This article performs a review of the literature on the area of heat transfer improvement employing a combination of nanofluid and inserts. Inserts are baffles, twisted tape, vortex generators, and wire coil inserts. The progress made and the current challenges for each combined system are discussed, and some conclusions and suggestions are made for future research.
Human gut is colonized by numerous microorganisms, in which bacteria present the highest proportion of this colonization that live in a symbiotic relationship with the host. This microbial collection ...is commonly known as the microbiota. The gut microbiota can mediate gut epithelial and immune cells interaction through vitamins synthesis or metabolic products. The microbiota plays a vital role in growth and development of the main components of human’s adaptive and innate immune system, while the immune system regulates host-microbe symbiosis. On the other hand, negative alteration in gut microbiota composition or gut dysbiosis, can disturb immune responses. This review highlights the gut microbiota-immune system cross-talk in both eubiosis and dysbiosis.
By starting with a two-fields model in which the fields and their derivatives are nonminimally coupled to gravity, and then by using a conformal gauge, we obtain a model in which the derivatives of ...the canonically normalized field are nonminimally coupled to gravity. By adopting some appropriate functions, we study two cases with constant and E-model nonminimal derivative coupling, while the potential in both cases is chosen to be E-model one. We show that contrary to the single-field -attractor model, there is an attractor point in the large N and small limits in our setup, and for both mentioned cases there is an attractor line in these limits that the r−ns trajectories tend to. By studying the linear and nonlinear perturbations in this setup, and by comparing the numerical results with Planck2015 observational data, we obtain some constraints on the free parameter . We show that by considering the E-model potential and coupling function, the model is observationally viable for all values of M (mass scale of the model). We use the observational constraints on the tensor-to-scalar ratio and the consistency relation to obtain some constraints on the sound speed of the perturbations in this model. As a result, we show that in a nonminimal derivative -attractor model, it is possible to have small sound speed and therefore large non-Gaussianity.
In the last decade, Human Activity Recognition (HAR) has become a vibrant research area, especially due to the spread of electronic devices such as smartphones, smartwatches and video cameras present ...in our daily lives. In addition, the advance of deep learning and other machine learning algorithms has allowed researchers to use HAR in various domains including sports, health and well-being applications. For example, HAR is considered as one of the most promising assistive technology tools to support elderly's daily life by monitoring their cognitive and physical function through daily activities. This survey focuses on critical role of machine learning in developing HAR applications based on inertial sensors in conjunction with physiological and environmental sensors.
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