Interior Resistance Research Articles

Fast thermo-osmotic flow through covalent organic framework multilayers for desalination

Thermo-osmosis, a liquid flow driven by temperature difference (∆T) in a solid-liquid interface, is promising to utilize low-grade heat energies for water desalination. However, the water flux of thermo-osmosis is hard to be enhanced. Herein, the potential of COF multilayers for thermo-osmotic desalination is investigated via non-equilibrium molecular dynamics (NEMD) simulations. To this end, TpMA multilayers with fine water stability and sub-nanometer pores are selected. The TpMA multilayers show excellent water flux and nearly 100 % NaCl rejections. By the analysis of interfacial and interior resistances, it is extrapolated that the TpMA nanosheet with a thickness of 200 nm has a water flux of 3096 L/(m2·h) at the ∆T of 60 K. By the molecular-level analysis, it is revealed that the coexistence of single-file and two-chains of water structure in the flow direction brings in high thermo-osmotic flows. The high NaCl rejection is due to the strong sieving effect of pores on the hydration of Cl−. Finally, the thermo-osmosis is compared with reverse osmosis. Based on the resistance analysis, it is found that the ∆T of 60 K is equivalent to the ∆P of 180 bar at most to reach the same water flux. These findings will inspire researchers with an alternative technology for high-efficiency desalination using low-grade heat energies.

Effect of Tautomerization on Water Desalination by Covalent Organic Frameworks

Covalent organic frameworks (COFs) have gained increasing interest as promising building blocks for desalination membranes due to their inherent porosity. Efforts have been made to prepare COF membranes and explore their transport mechanisms, however the effect of tautomerization has not been reported. Using non-equilibrium molecular dynamics, we discover here that a mere 0.5-Å atomic displacement between two tautomers of an imine-based COF (TpHZ) can surprisingly lead to dramatic changes in the desalination behavior of their multilayers. The tautomeric transformation (from TpHZ-NH to TpHZ-OH) improves the water permeability by about 1.6–3 times. The interior resistance rather than the entrance resistance is found to dominate the water transport. The weaker adhesion and the smoother channel path of TpHZ-OH result in a much lower interior resistance. Furthermore, NaCl rejection increases from ∼ 89 % to 100 % due to the stronger sieving effect resulting from the reduced compensatory effect of TpHZ-OH for ion hydrations.

Understanding the efficient seawater desalination performance of carbon honeycomb via reverse osmosis

This work investigates the performance of the carbon honeycomb (CHC) nanostructure in seawater desalination via reverse osmosis by molecular dynamics simulations. An ultrahigh water permeation rate is observed with a complete ion rejection. Increasing the pore size of CHC can further increase the permeation rate but slightly reduces the rejection rate. The transport resistance of water across the membrane is found to be dominated by the resistance at the pore entrance. The interior resistance of the membrane is low and only becomes significant when its thickness is large. With the aid of the enhanced ordering and retarded dynamics of the water molecules in the membrane, the low interior transport resistance results in the high water permeation rate. In addition, when salt ions penetrate into the CHC membrane under a higher driving pressure, the fast water permeation is not severely disturbed and the high salt rejection rate is retained because the water molecules and those of the ions are spatially segregative from each other. This work is helpful in deepening the understanding water and ion transportations in CHC and provides guidance for studying the applications of CHC in other ion-filtration processes, such as forward osmosis and capacitive deionization.

Study of dielectric and electrical properties in Co-(Fe–Ce-Nd) nanosized spinel ferrites

Ce–Nd doped Cobalt ferrite nanoparticles having composition CoFe2-2xCexNdxO4 (where 0.00 ≤x ≤ 0.10) were prepared by co-precipitation method. X-ray diffraction study confirms the formation of single-phase spinel ferrite. Temperature dependent dielectric and electrical properties has been studied with in the frequency range of 20Hz to 3 MHz. Dielectric constant and dielectric loss decrease as frequency increased while ac conductivity exhibit increasing trend with increasing frequency. The alternating current (AC) conductivity data were successfully modeled by using universal Jonscher's power law which implies that hopping of charge carriers is the governing mechanism in the conduction. Impedance study using Nyquist plots shows that grain boundary resistance is higher than the grain interior resistance. Diameter of Nyquist plots decreases with increasing temperature indicating the decrease in impedance and increase in conductivity. DC resistivity show decreasing trend with increasing temperature revealing semiconductor nature of synthesized nanoparticles. Current–Voltage measurements exhibit nonlinear hysteresis loop which authenticate the occurrence of resistance switching effect in synthesized composition.

Insight into the separation mechanism of graphene oxide membrane by designing dual layered structure

Graphene oxide (GO) membrane, made by self-assembly method, has been extensively studied. Various modification methods are used to improve the membrane performance. In order to make different modification methods work together and further study the separation mechanism of self-assembled GO membrane, a two-step self-assembly method, concluding filtration and subsequent evaporation, was used to fabricate dual-layered membrane with different nanosheets on the surface and inside the membrane. As control, simply laminated membranes were fabricated by filtration GO solution containing nanosheets with different properties. Comparing various self-assembled membranes, including dual layered membranes and simply laminated membranes, it can be found that dual layered membranes have higher permeability than simply laminated membranes. The structure with hydrophilic surface, hydrophobic interior and low permeability resistance, like a water trap on the back of some beetles for collection of water from air, has the highest water flux. The dense layered structure and highly charged nanosheets are very important to maintain high salt rejection and ion selectivity. The channels inside the membrane are very important for desalination. By designing the layered structure composed of nano materials, it is possible to obtain membrane structure with better permeability and separation performance.

Co-Estimation of State-of-Charge and State-of- Health for Lithium-Ion Batteries Using an Enhanced Electrochemical Model

Real-time electrochemical state information of lithium-ion batteries attributes to a high-fidelity estimation of state-of-charge (SOC) and state-of-health (SOH) in advanced battery management systems. However, the consumption of recyclable lithium ions, loss of the active materials, and the interior resistance increase resulted from the irreversible side reactions cause severe battery performance decay. To maintain accurate battery state estimation over time, a scheme using the reduced-order electrochemical model and the dual nonlinear filters is presented in this article for the reliable co-estimations of cell SOC and SOH. Specifically, the full-order pseudo-two-dimensional model is first simplified with Padé approximation while ensuring precision and observability. Next, the feasibility and performance of SOC estimator are revealed by accessing unmeasurable physical variables, such as the surface and bulk solid-phase concentration. To well reflect battery degradation, three key aging factors including the loss of lithium ions, loss of active materials, and resistance increment, are simultaneously identified, leading to an appreciable precision improvement of SOC estimation online particular for aged cells. Finally, extensive verification experiments are carried out over the cell's lifespan. The results demonstrate the performance of the proposed SOC/SOH co-estimation scheme.

Interior Resistance

The interior frequently masquerades a resistance to being clean, often demonstrating different levels of hygiene, containment, and control. Yet, it is the–body–inside that simultaneously resists and distributes infection within the mineral contexts of the building. Ever since Van Leeuwenhoek's (1993) discovery of a strange microbial world of bacteria and protozoa, societal, bodily, and spatial interpretations of clean have shifted. Evolving levels of cleanliness continually reposition the interior to become progressively more visually hygienic and meticulously super–clean. While medical need often leads and intensifies infection control, it is personal fastidiousness, compulsion, and media image that shape human attitudes and cultures to grime and dirt. Historically, “homes–of–the–future” reinforce a technologically sanitized prototype, a strain of which persists in the sterility of the ordered “show–home.” Each avoids the pathogenic realities of the–body–inside revealing esthetic traces of the Modernist ideals of clean lines and clean living that recur in contemporary images of minimal occupation. As we move to develop new hyper–clean and locked–down pandemic–proof interiors capable of immunizing and shielding occupants, this paper re–evaluates what it means to be clean and how the interior helps to resist and mediate these efforts. As concerns over antimicrobial resistance and interior touching increases, our protection from allergy, disease, and contagion are changing. The interior is increasingly playing a critical role in arbitrating biological infection, either through intelligent cleaning systems, infrastructure, or material science. This paper sets out the existing resistance to, and the conditions for, a new clean interior and posits where and what the future might conceive, including the advancement of immunology by reintroducing “dirt” back into interiors (mirroring Edward Jenner's deliberate infection of humans to develop resistance to smallpox) enabling better biological resistant to the outside world.

Experimental study on the viscosity of hybrid nanofluid and development of a new correlation

The present experimental analysis targeted on the preparation of water based (Al2O3-SiC-TiO2) ternary hybrid nanofluids by the mistreatment of two-stage methodology. Each vol. fraction sample of ternary hybrid nanofluids consists of an equal proportion of Al2O3-SiC-TiO2 nanoparticles for this analysis. The result for the dynamic viscosity of ternary hybrid nanofluids was examined for a temperature range of 35–40 °C and within a vol. fraction range of (0.01–0.1%). Analysis extended to the morphology characterization study through SEM image, together with an EDX analysis for 0.1% vol. fraction ternary hybrid nanofluid. Furthermore, based on the supported results, a new correlation was projected for the dynamic viscosity of ternary hybrid nanofluid, and also compared with the relevant literatures. The results revealed that the rise in vol. fraction, contains a larger role in increasing the interior resistance of fluid and the low vol. fractions have a weaker result on the viscosity of ternary hybrid nanofluids. The best relative consistency was discovered within 0.1% vol. fraction and, consistent with the obtained results, the margin of deviation within the intervals of ±2.6%.

Molecular Simulations of Water Transport Resistance in Polyamide RO Membranes: Interfacial and Interior Contributions

Abstract Understanding the transport resistance of water molecules in polyamide (PA) reverse osmosis (RO) membranes at the molecular level is of great importance in guiding the design, preparation, and applications of these membranes. In this work, we use molecular simulation to calculate the total transport resistance by dividing it into two contributions: the interior part and the interfacial part. The interior resistance is dependent on the thickness of the PA layer, while the interfacial resistance is not. Simulation based on the 5 nm PA layer reveals that interfacial resistance is the dominating contribution (> 62%) to the total resistance. However, for real-world RO membranes with a 200 nm PA layer, interfacial resistance plays a minor role, with a contribution below 10%. This implies that there is a risk of inaccuracy when using the typical method to estimate the transport resistance of RO membranes, as this method involves simply multiplying the total transport resistance of the simulated value based on a membrane with a 5 nm PA layer. Furthermore, both the interfacial resistance and the interior resistance are dependent on the chemistry of the PA layer. Our simulation reveals that decreasing the number of residual carboxyl groups in the PA layer leads to decreased interior resistance; therefore, the water permeability can be improved at no cost of ion rejection, which is in excellent agreement with the experimental results.

Development of a new correlation to determine the viscosity of ternary hybrid nanofluid

In this study, the experimental investigation on the effects of temperature and concentrations of nanoparticles on the dynamic viscosity of water-based Al2O3-CuO-TiO2 ternary hybrid nanofluid has been presented. The experiments were performed in the solid vol. fraction range of 0.01–0.1%, and temperature range of 35°C to 50 °C. Furthermore, the SEM image, together with an EDX analysis of 0.05% vol. fraction ternary hybrid nanofluid has been investigated. Experimental results revealed that the dynamic viscosity enhances with an increase in the solid vol. fractions and decreases with increasing temperature. However, the maximum enhancement of dynamic viscosity of 55.41% and 17.25% has been observed for 0.1% vol. fraction of ternary hybrid nanofluid compared to water-based Al2O3-TiO2 and Al2O3-CuO hybrid nanofluids, respectively, at a temperature of 45 °C. Due to the increase in the interior resistance of fluid and ternary hybrid, nanofluids have a weaker result on the viscosity. Also, with an increment of the temperature from 35 °C to 45 °C, a 23.64% decrement in dynamic viscosity is observed for ternary hybrid nanofluid. Finally, an accurate correlation with a maximum deviation of 1.5% has been proposed to predict the dynamic viscosity of Al2O3-CuO-TiO2/water ternary hybrid nanofluid.

Ionic conductivity of MgAl2O4-doped 8YSZ ceramics

The effect of spinel (MgAl2O4) addition on the ionic conductivity of 8 mol.% yttria-stabilized cubic zirconia (8YSZ) was investigated using the impedance spectroscopy. Undoped and 1, 5, 10, and 15 wt.% MgAl2O4-doped 8YSZ powders were prepared via colloidal process to ensure uniform mixing of the powders and to obtain a homogeneous microstructure. The ionic conductivity of the specimens was measured using a frequency response analyzer in the range of 100 mHz–13 MHz and 300–800 °C. Complex impedance analysis results of MgAl2O4-doped 8YSZ specimens showed that the grain interior resistance increased with MgAl2O4 addition; on the contrary, it also decreased the grain boundary resistance. Furthermore, while the grain interior conductivity of 8YSZ was decreased with MgAl2O4 addition, the grain boundary conductivity of 8YSZ enhanced with the presence of electronically conductive spinel oxide precipitated at the grain boundaries of 8YSZ. Moreover, the addition of MgAl2O4 to 8YSZ resulted in a decrease in grain boundary activation energies.

Fast Desalination by Multilayered Covalent Organic Framework (COF) Nanosheets.

Covalent organic frameworks (COFs) are penetrated with uniform and ordered nanopores, implying their great potential in molecular/ion separations. As an imine-linked, stable COF, TpPa-1 is receiving tremendous interest for molecular sieving membranes. Theoretically, atomically thin TpPa-1 monolayers exhibit extremely high water permeance but unfortunately no rejection to ions because of its large pore size (∼1.58 nm). The COF monolayers tend to stack to form laminated multilayers, but how this stacking influences water transport and ion rejections remains unknown. Herein, we investigate the transport behavior of water and salt ions through multilayered TpPa-1 COFs by nonequilibrium molecular dynamics simulations. By analyzing both the interfacial and interior resistance for water transport, we reveal that with rising stacking number of COF multilayers exhibit increasing ion rejections at the expense of water permeance. More importantly, stacking in the offset eclipsed fashion significantly reduces the equivalent pore size of COF multilayers to 0.89 nm, and ion rejection is correspondingly increased. Remarkably, 25 COF monolayers stacked in this fashion give 100% MgCl2 rejection, whereas water permeance remains 1 to 2 orders of magnitude higher than that of commercial nanofiltration membranes. This work demonstrates the rational design of fast membranes for desalination by tailoring stacking number and fashion of the COF monolayers.

Design of novel electrode for capacitive deionization using electrospun composite titania/zirconia nanofibers doped-activated carbon

Well-dispersed TiO2/ZrO2 nanofibers-doped activated carbon (AC/TiZr) were successfully synthesized as an electrode for the capacitive deionization (CDI) technique via electrospinning that was followed by a hydrothermal treatment. SEM, TEM, XRD, XPS and EDX measurements were employed to characterize the morphology, crystal structure and chemistry composition of the as-synthesized material. The electrochemical performance of the AC/TiZr nanocomposite modified electrode was measured using systematic cyclic voltammetry (CV) experiments. The highest specific capacitance for the AC/TiZr-based electrode is 251.3 Fg/g, which is higher than those of the AC (207.4 Fg/g) and TiO2/ZrO2 NFs (0.4 Fg/g)-based electrodes, and the interior resistance was also reduced. A desalination performance enhancement was obtained in the case of the AC/TiZr and the electrosorptive is 2.96 mg g−1. The implementation of the AC/TiZr nanocomposite provided a high potential for improving the efficiency of CDI.

Las mujeres escriben sobre la Resistencia francesa

Durante la Segunda guerra Mundial, la Resistencia interior francesa hizo necesaria la participación de todas las fuerzas civiles de la población francesa. La participación de las mujeres y su valor en la lucha contra la Ocupación quedaron reflejados en gran número de relatos testimoniales escritos por ellas; aquel escenario se trasladó también a la ficción literaria contribuyendo a mantener viva la memoria de aquellos años de contienda y de cuestionamiento de la identidad política y cultural de los pueblos europeos.

Tribological behavior and lubrication mechanism of self-lubricating ceramic/metal composites: The effect of matrix type on the friction and wear properties

This study aims at revealing the mechanisms of how matrix type and lubricant content affect the lubricating properties of graphite doped self-lubricating composites. Self-lubricating mechanism and tribological properties of three kinds of lubricating materials having different matrix-types (copper alloy, zirconia and alumina) are investigated. Results show that the effect of matrix type on the friction and wear properties of the composites is mainly related to its hardness and binding property with graphite. The variation of matrix-type causes significant changes in the degree of difficulty for extruding lubricants onto the friction surface from the material interior and plastic deformation resistance of composites, thus affecting the formation of lubricating and transferring films, and wear mechanisms of the materials. For copper alloy matrix that has low hardness and binding force with graphite, incorporating just a little graphite can greatly promote its lubricating performance. By contrast, alumina-graphite composite is difficult to achieve good lubrication when the graphite content (volume fraction) is less than 15% because of a relatively high hardness and brittleness of alumina matrix. Based on these analyses, we formulated some principles to design self-lubricating ceramic/metal composites.

Effect of microstructure on chemical stability and electrical properties of BaCe0.9Y0.1O3 − δ

Y-doped barium cerate BaCe0.9Y0.1O3 − δ was synthesised by a solid-state reaction method. Materials with different average grain sizes and grain boundary surface areas were obtained. The effect of microstructure on the chemical stability in the CO2 and H2O-containing atmosphere and electrical properties was analysed and discussed. To evaluate the chemical stability of BaCe0.9Y0.1O3 − δ , the exposure test was performed. Samples were exposed to the carbon dioxide and water vapour-rich atmosphere at 25 °C for 700 h. Thermogravimetry supplied by mass spectrometry was applied to analyse the samples before and after this comprehensive test. The mass loss for samples before and after the test and the amount of BaCO3 formed during the test were directly treated as the measure of chemical instability of BaCe0.9Y0.1O3 − δ in the atmosphere rich in carbon dioxide and water vapour. As it was observed, the BaCe0.9Y0.1O3 − δ chemical stability towards CO2 and H2O is not affected by the materials’ microstructure. Electrical properties of BaCe0.9Y0.1O3 − δ which differs with microstructure were determined using electrochemical impedance spectroscopy (EIS). It was found that the grain interior resistivity and activation energy of grain interior conductivity is microstructure independent. However, the effect on microstructure was seen on the EIS spectra in the range of grain boundary contribution. Therefore, the lowest activation energy and the highest conductivity were observed for a material with the lowest grain boundary surface area.

Estimation of the Interior Resistance Torque of Engine by Reverse Engineering

Estimation of the Interior Resistance Torque of Engine by Reverse Engineering

Dose Related Relationship of Depleted Uranium Associated with Certain Blood Electric Properties

In many radiation applications, there are clear dose effect relationships. On the other hand, there are many confusions about the radiation dose relationship that comes from depleted uranium on blood. Time study (0-16 hours) of three concentrations of uranyl acetate (1, 2 and 4 mM), which can reflect radiation dose multiplications, is used as depleted uranium on stored human blood. The exposed blood dielectric properties were measured using the three frequencies method at 25, 500 and 1000 KHz; the three doses at the different time intervals were compared. We find that some electric properties are not affected by increasing the dose during the whole time interval. No significant changes in neither the cell interior resistance nor in relative permittivity at 25, 500 and 1000 KHz at all the time interval, thus no dose relationship can be detected from them. The significant changes in plasma resistance, cell membrane capacitance and dielectric loss (at 25, 500 and 1000 KHz) are at only 9 hours of exposure and are dose related while there is no significant change at any other time interval. So we conclude that some electric properties if measured at certain time of exposure can give dose related relationship of depleted uranium on blood.

Preparation of a hybrid polymer solar cell based on MEH-PPV/ZnO nanorods

Hybrid polymer solar cells based on a conjugated polymer donor and a ZnO acceptor have drawn increasing attention because of the excellent electron-transfer performance and various nanostructures of the ZnO material. In the present study, ZnO nanorods were grown on an indium tin oxide-coated glass from a solution of Zn2+ via a hydrothermal route. Suitable growth conditions, including the Zn2+ concentration and growth time, were selected based on the scanning electron microscopy characterization. The poly [1-methoxy-4-(2-ethylhexyloxy-2,5-phenylenevinylene)] solution was filtered into vertically lined ZnO nanorods to form an active layer of the hybrid bulk-heterojunction solar cells. The hybrid polymer solar cell exhibits low efficiency of 0.045 %, which may be attributed to the defects in the ZnO nanorods and the high interior resistance of the cell.

Electrical Conductivity of 10 mol% Sc2O3–1 mol% M2O3–ZrO2 Ceramics

The oxide‐ion conductivity behavior of 10 mol% Sc2O3–ZrO2 co‐doped with 1 mol% trivalent metal oxide has been determined from 350°C to 700°C in air. All the powders were synthesized using conventional solid‐oxide route. XRD patterns collected at room temperature show the presence of β‐phase in the predominant cubic phase in 1Sc10ScSZ, 1Yb10ScSZ, and 1Y10ScSZ, although 1In10ScSZ consist entirely of β‐phase at ambient temperature. As evident from the cubic symmetry of 1Gd10ScSZ and 1Sm10ScSZ, the β‐phase can be suppressed by the slight addition of co‐dopant elements of larger ionic radius. The total conductivity of 1M10ScSZ initially increases with increasing size of the co‐dopant, reaches a maximum at ~0.95 Å and thereafter decreases. At 600°C, 1Yb10ScSZ exhibits the highest total conductivity, namely 14 mS/cm. The grain interior and the grain boundary follow similar conductivity trends with the maximum at 1In10ScSZ and 1Y10ScSZ, respectively. Around 475°C, 1In10ScSZ but not other compositions exhibits an abrupt drop in the conductivity on cooling, due to the cubic to β‐phase transformation. At 600°C, the activation energy for the oxide‐ion conductivity in 1M10ScSZ compositions ranges from 1.06 to 1.15 eV, with 1Yb10ScSZ exhibiting the smallest value. Long‐term stability studies of the conductivity were performed on the sintered pellet of 1Yb10ScSZ in both oxidizing and reducing conditions at 600°C. After 2000 h of exposure to air and reducing conditions, the 1Yb10ScSZ composition shows 9.1% and 12.0% loss in the total conductivity, respectively. After the first 1000 h, 1Yb10ScSZ exhibited a degradation rate of ~1.1%/1000 h in both the conditions. From impedance studies, it was shown that, during annealing, the grain interior resistivity remains almost stable, while only grain boundary contributes toward the rise in total resistivity in both the conditions.