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This study aims at investigating the effect of the substrate material on growth mechanism and also microstructure of Ta2O5 thin films. For this purpose, atomic force microscopy, scanning electron microscopy, and interferometry analyses were implemented to reveal the influence of silicon wafer and amorphous BK7 glass substrates on the nucleation and growth mechanisms of Ta2O5 thin films deposited via the radio frequency magnetron sputtering technique. Results indicated that those films with finer morphologies had relatively higher nucleation densities. Compared with BK7 glass substrate, crystals formed on the silicon wafer were shown to be finer and had lower mean areas in more nucleation sites. Moreover, optical properties and morphological characteristics of the films on the silicon substrates had much more endurance after the annealing treatment. It was observed that shift in the transmission spectra of the deposited films after the treatment was insignificant, implying high packing density of the films. However, a 6-nm shift in the transmission spectra indicated low density and high porosity of the films. Finally, atomic force microscopy analysis along with the light scattering measurements confirmed the formation of a low-roughness film on the silicon wafer substrates.

The goal of this study was to create highly efficient dye-sensitized solar cells (DSSCs) using strontium doped zinc oxide-reduced graphene oxide (Sr-doped ZnO/rGO) nanocomposites. As photo-anodes of DSSCs, ZnO, ZnO/rGO (with weight percent rGO in composites: 0, 0.01, 0.1, 0.5, and 1 wt%) and Sr-doped ZnO/rGO (with Zn1-xSrxO nanoparticle stoichiometry: x = 0, 0.02, 0.04, 0.06 and 0.08) nanocomposites were designed and characterized. AFM, FESEM, XRD, EDS, XPS, PL, and FTIR analyses were used to investigate the morphology and structure properties of prepared nanocomposites. UV–vis spectroscopy and photo-electrochemical measurements were used to investigate the efficiency of prepared photo-anodes. The efficiency (η) and short-circuit photocurrent density (JSC) of DSSCs based on Zn0.92Sr0.08O/rGO nanocomposite were 7.98 % and 18.4 mA cm−2, respectively. The results showed that doping Sr on ZnO/rGO nanocomposites resulted in a wide bandgap energy and increased the values of η, JSC, IPCE, and photo-anode electron transportability. These findings suggest that Sr-doped ZnO/rGO nanocomposites can provide a novel approach for increasing photo-electrochemical activity in ZnO-based DSSCs.

In this work, a novel functionalized magnetic Fe3O4@SiO2 core-shell nanoparticles grafted with carboxymethyl β-cyclodextrin (CM-β-CD) is utilized for adsorption of Pb(II) ions from aqueous solutions. The grafting reaction was performed via carbodimide method by using 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysuccinimide (NHS). The as-prepared nanoadsorbents were characterized by FTIR, SEM, TEM, XRD, TGA, and VSM. The grafting CM-β-CD on the Fe3O4@SiO2 core-shell nanoparticles enhances the ion adsorption capacity due to the strong abilities of the enormous –OH and –COOH functional groups in CM-β-CD to adsorb Pb(II) ions. The effects of factors such as the concentration of β-CD, contact time, initial ion concentration, adsorbent dosage, adsorption kinetics, and isotherms on the adsorption behavior were studied properly. The results depicted that the nanoadsorbents had good adsorption with the maximum adsorption capacity of 170 mg g−1 at 25 °C and pH 6.0. All the equilibrium adsorption kinetics of Pb(II) are fitted well to the pseudo-second-order model. The adsorption data were also found to follow the Langmuir adsorption isotherm model. In summary, the experimental Pb(II) ion adsorption data showed the prepared nanocomposites would be as promising adsorbents to remove various heavy metals from wastewater.

In this study, low-temperature CO2 decomposition to CO was investigated experimentally through a dielectric-barrier discharge plasma reactor with the main objective of improving CO2 conversion and ...

In this work, novel magnetic nanocomposite adsorbents were prepared by crosslinking β-cyclodextrin (β-CD) onto chitosan backbones by using epichlorohydrin as a crosslinker and in the presence of Fe...

High energy electromagnetic radiation or heavy charged particles are extensively used for medical treatment of certain cancers. Precise prediction or measurements of energy deposition of any types of radiation on tissue is critical in radiation therapy. In this research, the sensitivity of optical fiber dosimeters specifically doped with phosphor (P), Germanium (Ge) and Erbium (Er) are analyzed using Co-60 source at 169 cGy/min. The sensors are calibrated and the values of radiation induced attenuation (RIA) are evaluated at different temperatures. Nondestructive method of laser bleaching is shown superior to thermal bleaching for sensor recovery. The error in P- doped and Er- doped fiber sensors are estimated to be 6 and 4%, respectively. The fastest recovery is assigned to Er- doped fiber. The results show that Er- doped optical fiber sensor can perform ultrahigh sensitive low dosimetry of gamma- ray for medical application. The results of the present work can provide implications for further enhancement of radiation sensing for real- time dosimetry.

Geological storage of CO2 in saline aquifers and depleted oil and gas reservoirs can help mitigate CO2 emissions. However, CO2 leakage over a long storage period represents a potential concern. Therefore, it is critical to establish a good understanding of the interactions between CO2–brine and cement–caprock/reservoir rock to ascertain the potential for CO2 leakage. Accordingly, in this work, we prepared a unique set of composite samples to resemble the cement–reservoir rock interface. A series of experiments simulating deep wellbore environments were performed to investigate changes in chemical, physical, mechanical, and petrophysical properties of the composite samples. Here, we present the characterisation of composite core samples, including porosity, permeability, and mechanical properties, determined before and after long-term exposure to CO2-rich brine. Some of the composite samples were further analysed by X-ray microcomputed tomography (X-ray µ-CT), X-ray diffraction (XRD), and scanning electron microscopy–energy-dispersive X-ray (SEM–EDX). Moreover, the variation of ions concentration in brine at different timescales was studied by performing inductively coupled plasma (ICP) analysis. Although no significant changes were observed in the porosity, permeability of the treated composite samples increased by an order of magnitude, due mainly to an increase in the permeability of the sandstone component of the composite samples, rather than the cement or the cement/sandstone interface. Mechanical properties, including Young’s modulus and Poisson’s ratio, were also reduced.

This research investigates the microstructural and geotechnical properties, environmental impact, and economic benefit of cement kiln dust (CKD)-treated kaolinite clay with the addition of sodium chloride (NaCl). As a chemical admixture, NaCl is expected to enhance the strength properties of the clay soil stabilized by CKD. To verify this issue, the geotechnical characteristics of CKD-treated soils with different contents of NaCl (2.5, 5, and 10%) were examined. To this end, the Atterberg limits, standard Proctor, unconfined compressive strength and California bearing ratio (CBR) tests were conducted. Besides, scanning electron microscopy (SEM) analysis was used to observe the microstructural changes resulting from using additives. It was found that the addition of NaCl to the CKD-stabilized clay caused the maximum dry density to increase and the optimum moisture content to decrease. 10% NaCl enhanced the unconfined compressive strength of the CKD-treated soil to 18.7% and 8% higher than that of the NaCl-free specimen during 7 and 28 days of curing, respectively. These results were in accordance with the consequences extracted from the CBR behavior diagram. Moreover, cementitious compounds products in the mixtures were presumed to be the significant factor contributing to strength improvements based on the SEM results. The stabilized clayey soil with 15% CKD and 10% NaCl as environment-friendly method could significantly reduce energy consumption, e-CO2 emission, and cost of soil stabilization.

In this manuscript, a high-performance beam-steerable phased array antenna is introduced for fifth-generation (5G) mobile handsets. The configuration of the design is arranged by employing eight dielectric-insensitive L-ring/slot-loop radiators in a linear form on the top edge of the handset mainboard. The beam-steerable array design exhibits high radiation performances even though it is implemented on a lossy FR-4 material. The proposed design exhibits an impedance bandwidth of 18-20 GHz with the center frequency of 19 GHz. It provides satisfactory characteristics such as wide beam-steering, high gain and efficiency characteristics indicating its promising potential for beam-steerable 5G smartphones. The characteristics of the antenna array are insensitive for different types of dielectrics. Furthermore, the designed antenna array offers quite good radiation behavior in the presence of hand phantom.

The diffraction behavior of a polymer network liquid crystal (PNLC) was studied in in-plane switching (IPS) test cells and compared to the behavior seen in a neat liquid crystal. Due to the presence of polymer, the diffraction behavior was varied drastically: PNLCS are composites, which possess a specific domain size. The size of such polymer-induced domains was investigated with polarized optical microscopy and scanning electron microscopy. PNLCs are capable to result continuous optical phase modulation. It was found that electrical addressing with non-homogenous electric fields can be useful to vary the phase modulation profile as compared to a neat LC. The diffraction patterns seen in a nematic LC where influenced by the applied addressing voltage and showed some limited tunability already. However, in the PNLC, the diffraction patterns were drastically varied as compared to a neat nematic LC. These gratings showed responses localized to the electrodes, had higher tuneability and could also be useful t...

The development of microdischarges and the inception dynamics of subsequent microdischarges in an electrode arrangement consisting of a metal pin and a hemispherical dielectric-covered electrode, operated in air with a small toluene admixture, is studied. The discharge is operated with sinusoidal high voltage. A gated ICCD camera and a current probe enable the recording of images and current pulses of the single microdischarges, respectively, while the spatio-temporally resolved development is measured with a multi-dimensional time-correlated single photon counting technique. The overall discharge dynamics changes significantly if a concentration of 35 ppm toluene is added to dry air. A lower high voltage amplitude than in dry air is needed for stable discharge operation. This can be explained by the lower ionization energy of toluene compared to molecular oxygen and nitrogen. The microdischarge development is the same with or without admixture, i.e. a positive (cathode directed) streamer mechanism is observed. Lower mean power is dissipated into the discharge when toluene is admixed. The main effect caused by toluene admixture is the suppression of high-energy microdischarges in case of the cathodic pin half-cycle of the sinusoidal high voltage. The influence on the inception voltage by additional ionization mechanisms and volume memory effects, the consumption of energetic electrons for toluene decomposition reactions, and the modification of the surface by plasma treatment are discussed as possible reasons.

The impact of varying the co-doping concentration of a mesogenic and a non-mesogenic monomer in the reactive mixtures used to create a copolymer network LCs was investigated. Use of copolymer has been found to improve the response properties in the obtained liquid crystal composites. The polymer network in the studied copolymer network LCs was examined by scanning electron microscopy and the response times in various samples were investigated. Samples were prepared with various reactive mixtures, each of which had a constant concentration of mesogenic monomer, various concentrations of non-mesogenic monomer, and the same amount of photoinitiator. These reactive mixtures were filled in home assembled test cells with planar alignment and then exposed to UV light. With increasing concentration of the non-mesogenic monomer, the response properties of the resulting copolymer network LC were improved. Usually, if the overall polymer content in a polymer network LC is increased, the threshold voltage is also increased. However, both threshold voltages and response times were lowered and the response properties were thus improved in the studied copolymer network LCs. This unexpected behavior could be traced back to inducing a grainy polymer morphology of the copolymer network by using a non-mesogenic monomer.

Cement emulsified asphalt mortar (CEAM) as part of the slab track system is subjected to various combinations of repeated train loading and varying environmental conditions leading to fatigue cracking. In this respect, this research examined the fatigue cracking resistance behavior of CEAM through various testing methods applying fracture mechanics. Experimental tests conducted (i.e. indirect tensile (IDT) strength and semicircular bending (SCB)) showed that the fracture parameters (i.e. displacement at fracture, fracture energy, and critical strain energy release rate) could properly evaluate the fatigue performance of CEAM and distinguish additives’ impact at intermediate temperature. Furthermore, correlation analysis was employed to investigate the effect of test-related factors (e.g. specimen size, specimen thickness, notch length, and loading rate) on the assessed fracture parameters and specifying the most suitable parameter for fatigue cracking resistance evaluation of CEAM. According to the results, although the displacement at fracture and fracture energy were capable to assess the fatigue cracking behavior of CEAM, they exhibited to be specimen size dependent. Additionally, results of experiments conducted on CEAM specimens possessing various sizes and geometries along with the correlation analysis indicated that the critical strain energy release rate (Jc) is a potentially feasible parameter to recognize the fatigue cracking resistance of CEAM as a material parameter as it is independent of specimen size and geometry.

Most numerical simulation studies have focused on the effect of homogenous wettability on fluid flow dynamics; however, most rocks display spatially heterogeneous wettability. Therefore, we have used direct numerical simulations (DNS) to investigate wettability heterogeneity at pore-scale. We have built a quasi-3D pore-scale model and simulated two-phase flow in a homogenous porous media with homogenous and heterogeneous wettability distributions. Five different heterogeneous wettability patterns were used in this study. We observed that heterogenous wettability significantly affects the evolution of fluid interface, trapped saturation, and displacement patterns. Wettability heterogeneity results in fingering and specific trapping patterns which do not follow the flow behaviour characteristic of a porous medium with homogenous wettability. This flow behaviour indicates a different flow regime that cannot be estimated using homogenous wettability distributions represented by an average contact angle. Moreover, our simulation results show that certain spatial configurations of wettability heterogeneity at the microscale, e.g. being perpendicular to the flow direction, may assist the stability of the displacement and delay the breakthrough time. In contrast, other configurations such as being parallel to the flow direction promote flow instability for the same pore-scale geometry.

This study aims to examine the influence of untreated coal waste (UCW) and treated coal waste (TCW) as supplementary cementitious materials (SCMs) on the environmental, mechanical, durability, and microstructural characteristics of mortar mixes. UCW preparation procedure consists of sequential steps of crushing and grinding. Afterward, UCW is thermally activated through incinerating at 750°C to be promoted to TCW. Experimental work includes mixing mortar mixtures by partially replacing cement with the coal waste binders (UCW and TCW) at different incorporation levels of 4, 8, 12, and 16% of cement weight. Toxicity characteristic leaching procedure (TCLP) test was applied to investigate the environmental impacts of coal wastes. TCLP test results pointed out that heavy metals including Manganese, Cadmium, Lead, and Chromium could successfully entrap in the cement matrix. The compressive and flexural strengths as mechanical characteristics of mortar mixtures were determined at 3, 7, 28, 90, and 180 curing days. Moreover, the mortar specimens were immersed in 3% sulfuric acid (H2SO4) for 60 and 150 days. Durability results showed that the H2SO4 attack resistance of binary cement mortars containing 4% coal waste binders was better than the plain mortar. Based on the scanning electron microscopy (SEM) images, ettringite was found as the main hydration product of binary cement after 28 days; however, the existence of calcium silicate hydrate (CSH) and calcium hydroxide (Ca(OH)2) in the cement matrix of mixes after 90 days explains the more compact microstructure attained by using coal waste as cement replacement materials compared to control mixtures.

Immiscible fluid displacement and the trapping of residual oil and gas phases in the pore spaces of reservoir rocks is critical to geological operations such as carbon geo-sequestration and enhanced oil recovery. In carbon geo-sequestration, residual trapping is advantageous because it ensures long-term storage security of carbon dioxide (CO2). In contrast, residual trapping can pose significant challenges during waterflooding in oil recovery operations where large volumes of oil may remain trapped in the interstitial spaces of the porous reservoir rock and cannot be extracted, thereby reducing the efficiency of the recovery process. In such operations, residual trapping is strongly influenced by the inherent surface roughness of the solid rock matrix amongst many factors. Surface roughness occurs in natural reservoir rocks as a result of geological processes that physically, chemically or biologically convert sediments into sedimentary rock (known as diagenesis) and weathering.The effects of surface roughness on immiscible two-phase flow are currently not well understood. Previous investigations into residual trapping in porous media have mainly focused on the influence of factors such as pore geometry, wettability, fluids interfacial tension, mobility ratio and injection scenarios. Although some of these studies acknowledge the potential effect of surface roughness, there is still a lack of quantitative characterization and understanding of the influence of surface roughness on immiscible two-phase displacements in porous media.In this study, the impacts of surface roughness on immiscible two-phase displacement are quantified. Immiscible two-phase displacement of air by water was conducted in a custom laser-manufactured glass microfluidic chip (micromodel). The glass chip comprised a 2.5D micro-structure analogous to the pore network pattern (micro-structure) of a natural reservoir rock, Oolitic limestone. The pore network pattern consisted of cylindrical pillars 400 µm in diameter arranged in a rhombohedra type of packing, generated on to a glass substrate using an ultrafast, pulsed picosecond laser. Surface roughness is an innate characteristic of laser machined surfaces and as a result, small variations in depth of the porous micro-structure were observed (50 ± 8 µm). The average surface roughness (Sa) of the laser-machined structure was measured to be 1.2 μm.Experimental results for the rough micromodel exhibit high repeatability of fluid displacement patterns (preferential flow pathways) demonstrating that surface roughness has a strong influence on fluid invasion patterns and sweep efficiency and its effects must not be ignored. To ascertain the effects of surface roughness on the fluid displacement process, a direct numerical simulation (DNS) of the fluid displacement process was performed in OpenFoam using the Volume of Fluid (VOF) method assuming zero surface roughness. Comparing the experimental results with the numerical simulations, we show that surface roughness can significantly enhance residual trapping in porous media by up to 49.2%.

This study characterises the mechanical, rheological, induced heating, and induced healing behaviour of asphalt concrete containing steel wool fibers (SWFs) as the conductive constituent. Induced h...

Residual trapping in which ganglia of fluid are isolated and immobilised in porous media by capillary forces is innate to several subsurface engineering applications including carbon geo-sequestration. Residual trapping is highly significant in carbon dioxide (CO2) sequestration, as entrapment of supercritical CO2 in rock pore spaces, limits upward migration of the buoyant CO2 plume and enhances long-term CO2 storage security. It is estimated that residual trapping contributes up to 40% of overall trapping CO2 in the first century following injection (1). The amount of residual trapping depends largely on the wettability of the porous rock.Brine filled saline aquifers have been identified as having the largest potential for CO2 storage with an estimated cumulative storage capacity of 104 Giga-tons of CO2 (2). Likewise, the focus of many studies has been devoted to investigating residual trapping in water-wet, brine filled sandstone reservoirs, and little attention has been given to intermediate-wet and oil-wet carbonate reservoirs. However, until CO2 storage technology reaches maturity, initial CO2 sequestration projects will most likely be conducted in depleted and oil producing carbonate reservoirs due to economic benefits associated with CO2 enhanced oil recovery and the existence of installed infrastructure which can be reassigned for CO2 injection purposes (3). Accordingly, in this work, the intrinsically water-wetting surfaces of laser fabricated glass micromodels (4); which are two-dimensional representations of natural porous rock structures, were chemically modified to imitate intermediate-wet reservoir conditions through a silanization procedure. Imbibition experiments were conducted in the micromodels using two proxy, CO2-brine fluid pairs; deionized (DI) water and n-decane as well as DI water and air.Fluid displacement under intermediate wettability was analysed and compared with water-wet conditions and residual fluid saturations were quantified for different porous structures. The Volume of Fluid method was used to simulate the experiments in OpenFOAM. Results from the micromodel experiments were used to validate the simulations.This work has demonstrated that fluid displacement during the imbibition process occurs through a series of cooperative pore-filling events under intermediate-wet conditions and the presence of dead-end pores was found to enhance residual trapping of the non-wetting fluid. Coupling experimental and simulation studies provides a unique insight to multiphase flow under intermediate wet conditions. Acknowledgements This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (MILEPOST, Grant agreement no: 695070). This paper reflects only the authors’ view and ERC is not responsible for any use that may be made of the information it contains. ReferencesLi X, Akbarabadi M, Karpyn ZT, Piri M, Bazilevskaya E, Experimental Investigation of Carbon Dioxide Trapping Due to Capillary Retention in Saline Aquifers, Geofluids, 2015;15(4):563–76. Benson; GEA; Iiasa. Chapter 13: Carbon Capture and Storage. Global Energy Asssessment. 2012. Al-Menhali AS, Menke HP, Blunt MJ, Krevor SC. Pore Scale Observations of Trapped CO2 in Mixed-Wet Carbonate Rock: Applications to Storage in Oil Fields. Environ Sci Technol 2016;50(18):10282–90. Wlodarczyk KL, Carter RM, Jahanbakhsh A, Lopes AA, Mackenzie MD, Maier RRJ, Hand DP, and Maroto-Valer MM, Rapid Laser Manufacturing of Microfluidic Devices from Glass Substrates. Micromachines. 2018; 9(8)

Surface tension plays a key role in many applications such as spraying, diffusion in porous media, birds drinking, etc. But simulation of surface tension is challenging because it involves a moving interface, topology changes, and triple lines where the dynamic contact angle is generally unknown. Surface tension is a macroscopic force resulting from microscopic interactions. Based on recent developments of the Finite Volume Particle Method, we propose a surface tension formulation directly derived from the macroscopic force for a single-phase configuration. Each particle represents a physical volume of fluid, and the free-surface is the union of the free-surfaces for each particle. Motion of these particles will cause a deformation of the free-surface and change its energy. Through analytical computation of these changes, the surface tension force is modelled by a particle–particle interaction that does not involve parameters other than a constant surface tension γ and the equilibrium contact angle at the triple line, θ e . After a formal derivation of the force, we use it in various drop applications to validate its behaviour, both qualitatively and quantitatively. We also show that empirical dynamic contact angle models can advantageously be replaced by a physically meaningful surface roughness model. In this case, the roughness parameter has to be empirically evaluated.

This research investigates the crack healing ability of activated carbon (AC) modified asphalt concrete through microwave radiation. As a binder-based conductive additive, AC is expected to increase the electro-magnetic radiation absorption of asphalt binder. To verify this issue, neat and modified binders with different contents of AC were exposed to microwave radiation. It was found that the temperature of AC modified binder increased considerably after microwave heating compared to that of the neat binder. This observation can be regarded as a driving force to use AC in asphalt for the healing purposes. Moreover, statistical analysis of testing results showed that the AC modification did not have any detrimental effect on the asphalt performance. For further evaluation of the healing ability of AC modified asphalt, cycles of breaking and healing were applied to a number of semicircular bending (SCB) and indirect tensile (IDT) testing samples. Notch length, damage level (number of breaking-healing cycle), and aggregate source were found to have significant effects on the induced healing efficiency. The obtained results confirmed that AC is a potentially viable and robust binder-based conductive component for induced heating and healing of asphalt concrete.

The purpose of this study is to investigate the effect of various parameters on the welding process with high-velocity projectiles. For carrying out Impact Spot Welding tests, a single stage compressed gas gun impact test facility was used to launch flat- and conical-nosed projectiles within the velocity range from 100 to 150 m/s and performed. Different types of materials such as steel, copper, brass, and aluminum alloy were used. In the present experimental study, the steel plate with a thickness of 4 mm was considered as a back layer and the other plates made of copper, brass, and aluminum alloy were considered as front layers. Different gaps of 0.1, 0.2, and 0.5 mm were considered between the layers. The shape of the welded interface was studied by Scanning Electron Microscopy (SEM). The depth of penetration in the specimen and the kinetic energy of the projectiles were calculated. The experimental results showed that a complete bonding has occurred in the collision zone, especially in the central areas.

This study focused on induced heating and healing of asphalt concrete. Carbon black (CB) was added to asphalt binder as a conductive component to increase the electro-magnetic sensitivity of the asphalt concrete and to accelerate the heating and healing rate of this material. Samples were fabricated using siliceous and limestone aggregate types. Then, semicircular bending (SCB), indirect tensile (IDT), and uniaxial compressive tests were conducted in order to study the mechanical properties of the CB modified asphalt concrete. In addition, a healing index (H.I) was introduced to evaluate the performance of the CB modified asphalt concrete under repeated breaking-healing cycles. Experimental results indicate that the CB considerably enhanced the mechanical strength of asphalt concrete. At the first breaking- healing cycle the CB could properly heat and heal the asphalt concrete such that the H.I was up to 70 and 60 percent at low and intermediate temperatures, respectively. Also, as the breaking-healing cycles increased, the H.I decreased. An empirical-mechanical model was then proposed to clarify the influences of the damage level and effective healed length on the induced healing index. It was concluded that the healing index of the asphalt concrete depends on modes of the mechanical testing, crack length, damage level, and temperature.

We use molecular dynamics (MD) simulations to examine the structural and dynamical properties of deep eutectic solvents (DESs)-based boron nitride nanotube (BNNT) nanofluid. The impacts of nanotube diameter on the physicochemical parameters of the systems under consideration are investigated. It is found that the addition of BNNT to DES increases viscosity as a result of a decrease in the diffusion coefficient of DES species. Similarly, increasing the diameter of the BNNT causes an increase in viscosity while reducing the diffusion coefficient of glycerol. The assessment of interaction energy and the number of hydrogen bonds rationalizes and explains these results. The density profile, radial distribution function, the number of hydrogen bonds, and orientation of two species are estimated to provide a molecular explanation of DES species behavior within and outside BNNTs. Our results reveal that the diameter of the BNNT influences the arrangement and number of DES species inside BNNTs. Except for the (8, 8) BNNT, where DES species are organized in a straight chain, the cylindrical structure of DES species is inferred inside all BNNTs. Likewise, various obtained physicochemical properties for glyceline are found in good agreement with experimental data. This new understanding of the DES-based nanofluids structure will help to understand the properties of these green novel solvents from the viewpoint of molecular scale in chemical processes, as well as suggest a powerful framework in solvent design applications.

Dynamic rheological measurements provide a valid determination of the ability of polymeric ingredients to compensate the reduced contribution of fat to texture and mouthfeel, as well as provide an ...

Induced heating-healing of asphalt concrete is rapidly emerging as an innovative repairing technique in pavement engineering. In this method, asphalt concrete is heated using the external electromagnetic field. As a result, the viscosity of the asphalt binder decreases, leading to the movement of the asphalt binder through the cracks and healing them. Researchers have been intensively investigating this technique as a potential practical method to heal the cracks and extend the service life of asphalt concrete and pavement. This review paper itemizes the applications of induced heating in pavement engineering. The induced healing, as the predominant application, was compared against the self-healing mechanism in asphalt concrete. Different types of heating sources and their effects on induced heating-healing of asphalt concrete were investigated. Different types of conductive additives (i.e., fiber, powder, and granular) are utilized to enhance the induced heating-healing efficiency. This study covers the influence of conductive additive type on the rate of induced heating-healing, thermal conductivity, heat transfer, temperature distributions, and mechanical characteristics of asphalt concrete. Besides, the effects of different parameters (i.e., mixture components, aggregate gradation and type, specimen dimension, breaking temperature, crack configuration, mechanical damage, aging, moisture/freeze-thaw damage) on the induced heating-healing process in asphalt concrete were introduced and discussed in detail. Afterward, the sustainability aspects of the induced heating-healing technique (i.e., cost, greenhouse gas emission, and energy consumption) were investigated and compared with existing asphalt concrete repairing methods. Finally, the existing challenges regarding the induced heating-healing technique and suggestions for future studies were presented.

Photocatalytic behavior was investigated for TiO2–graphene nanocomposite in the degradation of acid orange 7 (AO7) as a model pollutant under ultraviolet light in aqueous solution. XRD, SEM, TEM, DRS, FT-IR and EDX techniques were used for the characterization of the prepared nanocomposite. The effect of synthesis variables such as weight ratio of TiO2 to graphene and operational key factors such as initial dye concentration, irradiation time, catalyst dosage and solution distance from UV lamp were studied in the photocatalytic degradation of AO7. This excellent catalytic ability is mainly attributed to the synergic effect of photocatalyst and adsorbent. The effect of operational variables was optimized for the photocatalytic degradation of AO7 as a pollutant model using the RSM technique. In this case, the amount of the determination coefficient (R2 = 0.97) shows that 97% of the variability in the response could be described by the model. The maximum degradation efficiency (96%) was achieved at the optimum operational conditions: catalyst dosage of 0.5 g L−1, the irradiation time of 50 min and distance the solution from UV lamp of 0.3 cm.

With regard to the construction of high speed railways, the role of cement emulsified asphalt mortar (CEAM) is of crucial importance as a leveling and damping material. In this respect, there are many research studies on exploring the mechanical, durability, fatigue, and rheological characteristics of CEAM. Nonetheless, developing greener types of CEAMs would be of great interest for developing transportation infrastructures with low carbon footprint. Accordingly, the current study aims to evaluate the effects of partial replacement of cement with low pozzolanic activity ground granulated blast furnace slag (GGBFS) and silica fume (SF) on mechanical and fatigue performances of CEAM. In addition, a central composite design (CCD) with response surface methodology (RSM) was applied to the results to develop statistical models. The results obtained reveal that utilizing low pozzolanic activity GGBFS showed no significant effect on uniaxial compressive strength (UCS) and decreased the indirect tensile strength (IDT) slightly. Moreover, both UCS and IDT heightened through the inclusion of SF. As a result, the addition of SF would compensate for reduction in some mechanical properties caused by GGBFS with low pozzolanicity. Furthermore, based on the results, semi-circular bending (SCB) test properly differentiated the effects of cement replacement with GGBFS and SF on fatigue resistance of CEAM.

Dispersion of ferroelectric- and ferromagnetic nanoparticles in liquid crystals (LCs) is investigated in the last decades. Recently, doping multiferroic-BiFeO3 nanoparticles in the LCs has become of interest. These nanoparticles have coupled ferroelectric- and ferromagnetic properties at ambient temperature. In the present experiments, a nematic LC was doped with a low concentration of BiFeO3 nanoparticles, synthesized using a modified Pechini method. The particles were characterized and their dispersions in heptane with an added surfactant were used for doping of the LC. The measured dielectric constants in the doped LCs varied as compared to the pure LC. It was shown that the presence of a magnetic field in the cooling process (cooling down from isotropic to anisotropic phase) of the LC cells leads to a significant increase of dielectric anisotropy. Also, the transition temperature decreased in the nematic-isotropic transition temperature for the doped sample.

A fast-switching, tunable color filter was found in a copolymer network liquid crystal (LC), which was in situ generated in a conventional LC test cell with parallel aligned glass plates and investigated with polarized light. Polarization filters were used to convert the tunable optical phase retardance of the test cells to birefringence colors as is always possible in a LC test cell with carefully adjusted cell gap and effective birefringence. The cell gap of the samples could be adjusted to a value of 9 μm, which is not easily possible in a polymer LC composite without creating defects. In these samples, the typical pastel colors seen frequently in birefringent samples could be avoided. The transmittance spectra were recorded and converted to CIE 1931 color coordinates, which showed that the colors seen had a reasonable distance to the white point. The electro-optic switching times of the samples were investigated: Fast responses of t on +t off

A functionalized graphene-dendrimeric system was designed via Fe3O4 nanoparticle (NP) as a magnetic nanocarrier for co-delivery of doxorubicin (DOX) and melatonin (MLT). Accordingly, β-Cyclodextrin (β-CD) was modified by creating amine functional groups. The modified β-CD was grafted with Graphene oxide (GO), and the resulting platform gain many functional groups, including the hydroxyl (-OH), carboxylic acid (-COOH), and amine functional groups (−NH2). Finally, magnetic NPs were synthesized on the prepared platform to efficiently controlling and targeting drugs to tumor sites. The human osteosarcoma cell lines including Saos-2 and MG-63, as well as Human Bone Marrow Mesenchymal Stem Cells (hBM-MSC) line, were used to determine the in vitro biological effects of the functionalized graphene-dendrimeric system. The magnetic nanocarrier has encapsulation efficiency (EE) values of 99.92% for DOX and 21.5% for MLT. The biocompatibility tests of the nanocarrier revealed that the magnetic nanocarrier was appropriate as a drug carrier. Co-delivery of DOX and MLT with an efficiently anticancer performance was also was confirmed by cellular uptake, 4′,6-diamidino-2-phenylindole (DAPI) staining, and apoptosis analysis in comparison with free DOX and MLT. Moreover, there was a synergy in the antitumor effect when MLT was combined with DOX, especially in the nano-formulation form, which may be due to the down-regulation of X-linked Inhibitor of Apoptosis (XIAP), survivin, and human telomerase catalytic subunit (hTERT) (p

An imprinted electrochemical sensor was developed for the determination of the antibiotic oxacillin (OXC). A screen-printed carbon electrode (SPCE) was modified with gold nanourchin and graphene oxide, and then aniline was electro-polymerized in the presence of OXC to obtain a molecular imprint on the SPCE. The morphologies in sequential modification processes and the electrochemical behavior of the modified SCPE were characterized by field emission scanning electron microscopy and cyclic voltammetry. The performance of the sensor was evaluated by differential pulse voltammetry. At a typical peak potential of 0.82 mV (vs. Ag/AgCl), response is linear in the 0.7–575 nM OXC concentration range. The electrochemical sensitivity is 97.6 nA nM −1 cm −2, and the detection limit is 0.2 nM. The relative of replicate assays is 2.6% (for n = 6) at an OXC concentration level of 200 nM. The sensor is sensitive and selective. It was successfully applied for the detection of OXC in spiked cow’s milk.

Purpose: In some gamma spectroscopy experiments, neutrons may also be present, so depending on experimental conditions, Gamma spectroscopy can be influenced by the presence of neutrons. Materials and Methods: In this study, a NaI(Tl)(63 mm×63 mm) detector is used to investigate the effects of fast neutrons on the spectrum of gamma photons. The radiation source used in these experiments is made up of two point sources: an AmBe (50 mCi) neutron source and a 137Cs(10 mCi) gamma source. Results: Results were determined through both measurements and Monte Carlo simulation (MCNPX) under two different experimental conditions and were compared. When the detector is placed under an angle to the source, gamma photon energy peaks resulting from inelastic interactions of the fast neutrons with the detector materials and surrounding materials in the energy range of 0.1-0.9(MeV) are pretty visible in the gamma main spectrum. These results can be used to optimize industrial tomography experiments carried out with NaI(Tl) scintillators. Conclusion: Also, the results show that the detection of fast neutrons with a NaI(Tl) scintillator is possible with low efficiency.

The prediction of deep eutectic composition is hard and so far, has been distinguished by trial and error. Therefore, in this work, molecular dynamics simulations were performed for specifying the composition of the eutectic point of phenyl propionic acid (Phpr) and choline chloride (ChCl) mixtures. The distinctive properties of the Phpr and ChCl eutectic mixture at the composition of the eutectic point were investigated and were compared to other eutectic mixtures with the different mole fractions of Phpr and ChCl. Structural properties such as radial distribution function (RDF), coordination number, hydrogen-bond number, interaction energies, and dipole moment of species, as well as dynamical properties such as mean square displacement (MSD), viscosity, and self-diffusion coefficient were analyzed. The obtained results of structural properties indicated that each chloride anion is surrounded by two Phpr molecules for deep eutectic point states that is in good agreement with available experimental reports. Moreover, the viscosity of studied mixtures evaluated by the Green-Kubo method was found to be consistent with the reported experimental data. Besides, the stress-autocorrelation function (SACF) and convergency of viscosity with time were calculated. Finally, the eutectic point could be detected by the changes in the trends of total van der Waals interaction energies and the viscosity.

In this research, we presented an energy-based approach to characterize the induced heating properties of asphalt concrete under the electromagnetic field. The induced heating of asphalt concrete under electromagnetic power is an innovative technique in pavement engineering for applications of induced healing, deicing, mixture heating, and improving the compaction of asphalt pavement. The efficacy of induced heating in asphalt concrete is often characterized using the surface temperature during the induced heating process. The experimental results indicated that the distributions of the electromagnetic field and thermal energy inside of asphalt concrete depend on the specimen dimension, causing inaccurate induced healing characterization. While the analysis of specimens’ surface temperature with various dimensions led to a more accurate result, there were yet disagreements between the rank orders of induced heating and induced healing. As the speculation, the heterogeneous distributions of the electromagnetic field and thermal energy inside of asphalt concrete can cause inaccurate characterizations. To remedy the mentioned problems, after the induced heating cycle, the specimens were left at room temperature to cool, and meanwhile, the surface temperature versus time was measured. According to the convection mechanism of heat transfer, the value of the outward heat flux was calculated. The integration of heat flux over the cooling stage time results in the total thermal energy absorbed by specimens during the induced heating process. Additionally, we proposed parameters of energy storage history and temperature storage history. The results show that the suggested energy-based approaches can properly rank the induced heating capability of asphalt concrete with more accuracy compared to the conventional surface temperature approach during the heating stage.

The head scatter factor (Sc ) is important to measurements radiation beam and beam modeling of treatment planning systems used for advanced radiation therapy techniques. This study aimed to investigate the design of a miniphantom to measurement variations in collimator Sc in the presence of shielding blocks for shaping the beam using different field sizes. Copper, Brass, and Perspex buildup caps were designed and fabricated locally as material with three different thicknesses for buildup caps (miniphantoms). Measurements were performed on an Elekta Compact medical linear accelerator (6 MV) in Shafa Kerman Hospital, Iran. The Farmer-type ion chamber FG65-P (Scanditronix, Wellhofer) was used for all measurements. To measure the Sc , miniphantom was positioned in a stand vertical to the beam central axis. The data indicate that the Sc measurements using different buildup cap materials and thicknesses in 5 × 10, 7.5 × 7.5, and two 10 × 10 cm Cerrobend shield blocks ranged 0.98 to 1.00, 1.04 to 1.05, and 1.04 to 1.06, respectively. Also, it was observed that by increasing the block shield area from 50 cm2 to both 56.25 and 100 cm2, the Sc increased in all situations. Results showed that using Brass compared to Perspex and Copper has less uncertainty due to its simple preparation and cutting which is useful to measurement of variations in collimator Sc and shaping the photon beam.

Through the strategic highway research program (SHRP) project, time-temperature superposition (TTS) was used to reduce the loading time of bending beam rheometer (BBR) test. Based on TTS, stiffness of the asphalt binder after a two-hour loading time is similar to that after 60 s at 10 °C above. This study attempted to evaluate the TTS validity using finite element (FE) method by developing master curves in a broad range of low temperatures. The results indicated that TTS was neither valid for modified asphalt binders nor for neat binder. Also, in addition to the loading time dependency of m-value, limiting values of stiffness and m-value find no rheological acceptance. As a remedy, thermally induced stress (TIS) due to cooling of asphalt binder was obtained from finite element method and employed to meet rheological needs. TIS indicates similar consequences with existing field data and previous studies related to gradation of different modified asphalt binders with almost similar content of modifiers.

Applying cutting tool with longer functioning time is a vital issue in machining of the nickel-based super alloys. However, the experimental analysis of this problem is quite expensive. Thus, three-dimensional numerical simulation of tool wear propagation in turning of Inconel 625 super alloy is taken into account, in this study. The cutting insert with complex geometry is modeled by using a reverse engineering method. Based on the cutting tool and workpiece material, Usui wear rate model is exerted to estimate the tool wear rate. In the first section, characterization of TiAlN-coated carbide tool, which is suggested by catalogue, on wear resistance is evaluated and then simulation results are validated with experiments. As a result, increment of depth of cut is the most effective factor on the generation of temperature and stresses on the tool faces resulting in wear rate acceleration. In the second section, different commercial coatings with multicompositions are applied in the simulation to find the best performance against wear. Finally, TiCN coating outperformed other coatings in turning of Inconel 625.

Thermal cracking is the prevalent type of distress experienced by asphalt pavements in cold regions. It is widely assumed that when thermal stresses induced in the pavement exceed the tensile strength of the asphalt surface layer, cracking occurs; however, the role of thermal fatigue should not be ignored. To better describe the low-temperature (LT) performance properties of modified asphalt binders, a new parameter, normalised tensile stress (NTS), was defined in this research. NTS values were compared with bending beam rheometer (BBR), direct tension (DT) and semi-circular bending (SCB) fracture test results. The m-value parameter of the BBR test specifies the type of asphalt binder. This classification changes as the loading time changes and is only valid in the linear viscoelastic range. It showed limited sensitivity to changes in the material properties of modified asphalt binders that showed superior LT damage resistance. In contrast, the results from the DT, SCB and NTS parameters were sensitive to...

Examination of cutting tool wear by experimental approaches is too costly. The main objective of this work is to develop an accurate 3D finite element model to predict the tool wear of PVD-TiAlN coated carbide and ceramic inserts in turning of Inconel 625. Thus, the cutting tools with complex geometries are modeled. Usui wear rate model is used to estimate wear rate where its constant parameters are achieved based on the cutting tools and workpiece material. The verification tests showed that the predicted values are in good agreement with the experiments. Moreover, among the cutting parameters, the increase of depth of cut were found as the most effective factor on the generation of temperature and stresses on the tool faces.

Rapid tool wear is one of the major machinability aspects of nickel-based super alloys. In this article, the effect of cutting parameters on material removal rate and tool wear of a whisker ceramic insert in turning of Inconel 625 was examined. Optical microscope and scanning electron microscope were applied to measure and study tool wear mechanism. Response surface method was used to develop a mathematical model which confirmed by experimental tests. The statistical analysis done by analysis of variance showed that depth of cut is the most effective factor on the tool wear. Experiments showed that increment of feed rate had an insignificant effect on the progress of flank wear, and it is an important controlling factor when material removal rate is considered as a desired output. Finally, optimized cutting condition is presented in this work.

Summary Relative permeabilities (kr) are crucial flow functions governing the fluid distribution within and production from petroleum reservoirs under various oil-recovery methods. To obtain these important reservoir parameters, conventionally, it is required to take rock samples from the reservoir and perform appropriate laboratory measurements. Although kr is expressed as a function of fluid saturation, it is now well-known that kr values are affected by pore structure and distribution, absolute permeability, wettability, interfacial tension (IFT), and saturation history. These rock/fluid properties often change from one region of the reservoir to another, but it would be impossible to perform kr measurements for all regions of a reservoir. Generally, performing experiments on a core with higher permeability is faster and easier than a low-permeability rock. Therefore, assuming all other parameters such as wettability, IFT, and displacement direction are the same for two rocks with different permeabilities, the question becomes how do we estimate the kr of a rock with lower permeability from available (measured) kr of a higher-permeability rock? How do we account for wettability and IFT differences? A normalization technique has been proposed to remove the effect of irreducible water and trapped saturations, which would be different under different conditions. The relative permeabilities can then be denormalized and assigned to different regions (rock types) of the reservoir on the basis of their own irreducible water and trapped saturations. The objective of this study is to introduce a methodology to predict the gas/oil kr for new rock/fluid conditions (such as permeability, wettability, and IFT) by use of existing gas/oil kr data measured at different conditions. By use of measured data from coreflood experiments, we show that by applying an appropriate normalization technique one can adequately predict kr of rocks with different permeability and wettability conditions in two-phase gas/oil flow. However, the results show that the effect of IFT change cannot be captured by normalization techniques. To improve the methodology, a new hypothesis is introduced and proposed here on the basis of dynamic trap saturation. Finally, by use of our experimental data, we evaluate the validity of the Coats (1980) IFT scaling method. We demonstrate the shortcomings of the method and offer an improvement to its prediction.

The induction heating-induced healing of asphalt concrete is an innovative method of crack repairing. As concluded in previous studies, the temperature of asphalt concrete, raised through the induction heating, directly affect the process of the induced healing. As the speculation in this study, not only the temperature level but also the rheological properties of asphalt binder at the relevant temperature affects the induced healing process in asphalt concrete. In this study, the correlation between zero shear viscosity of asphalt binder and induced healing efficiency of asphalt concrete was scrutinized. The neat and modified asphalt binders with carbon black and activated carbon were utilized in the asphalt concrete comprised of limestone and siliceous aggregates. Initially, the influences of specimen dimension on the rate of induction heating were investigated. Then, the zero shear viscosity of asphalt binders, resembling the low-speed movement of melted asphalt binder, was identified based on data acquired from the rotational viscometer test. The semi-circular bending test was conducted for assessing the induced healing process of the asphalt concrete under repeated cracking-healing loading scenarios. The analysis of the induced healing index for different asphalt concrete types confirms the concurrent influences of temperature level and rheological properties of asphalt binders. Moreover, it can be deduced that the zero shear viscosity and capability of asphalt binder to move at far low-speed play a pivotal role in the accomplishment of induced healing in asphalt concrete. The proposed approach can be beneficially used to characterize the induction heating-induced healing characteristics of asphalt concrete specimens made of different ingredients.

The nature and physical parameters of dielectric barrier discharges (DBDs) are determined by the presence of dielectric material in the discharge gap. The charging of the dielectric barrier is responsible for the non-thermal regime as it limits the local energy dissipation. In an operating DBD residual surface charges can influence the distribution and development of the plasma in the following discharge cycles1. In order to learn more about residual surface charge role an experiment with a rotating dielectric electrode and a pin electrode (325 μm tip radius) is realized2. The rotating dielectric barrier enables DBD-operation with DC high voltage and, the remaining surface charges are removed by a second grounded electrode which is sliding over the dielectric. Thus, single, repetitive microdischarges in air at atmospheric pressure are ignited without participation of residual surface charges. These microdischarges were investigated by ICCD camera, electrical measurements and time-correlated single photon counting (sub-ns, sub-mm and spectral resolution). For positive polarity of the pin electrode a positive streamer starting from the middle of the gap followed by a secondary wave starting from the metal electrode is observed. For negative polarity an anode directed wave of light and a weaker glow in front of the cathode are obtained.

In the present work, the effect of homogenizing time and temperature on the mechanical properties and microstructural evaluation of dissimilar IN-738/MBF-80/FSX-414 TLP joints was studied. The joints were made at the optimum bonding temperature of 1150 °C and homogenized at 1175, 1200 and 1225 °C for 1–6 h. Light and electron microscopes were used to investigate the microstructure. To study the hardness and alloying elements concentration profiles across the joints, the microhardness test and Wave length-Dispersive x-ray Spectroscopy (WDS) analysis were used, respectively. x-Ray Diffraction was used for identification of the phases. Shear tests were performed to measure shear strength of the joints. The results showed that, after homogenizing treatment at 1200 °C for 3 h, undesirable phases in the joint region were eliminated markedly while these phases were stable after 1 h homogenizing at the same temperature. Recrystalization at the joint region close to the FSX-414 base metal was seen at this temperature. At the same region, homogenizing treatment at 1225 °C led to intercellular carbide dissolving and recrystallization. At this temperature, grain boundaries liquation and precipitation coarsening occurred. The results of shear tests showed that, the shear strength of the joints was enhanced by about twice after homogenizing at 1200 °C in respect to the as-bonded samples.

In this paper heat pipes have been constructed and tested using solutions of ethanol and water as the working fluid at different tilt angles and concentrations. Tests were carried out to investigate the effects of ethanol concentration as well as the pipe evacuation and the use of a wick inside the pipe to ensure a continuous performance of the system. The tests indicate that ethanol in the solution enhances the heat pipe performance at low heat flux, and that concentrations of 50% and 75% show the best performance characteristics in transferring the heat. An efficiency of about 52% was obtained for the heat pipe operated solar collector in this case. It was concluded that the evacuation of a heat pipe or using a wick do not add much effect to the enhancement of a heat pipe performance, and that the collector had its highest heat transfer coefficient at a tilt angle of 35°. Using the results from testing the heat pipes, a thermo-syphon type solar water heater was developed, using the high efficiency heat pipe with evacuated glass cover tubes. The results of these experiments revealed that the collector water flow rate and evacuation of the glass cover tubes had little effect on the enhancement of the solar collector thermal performance.

A picosecond laser is used for rapid prototyping of enclosed microfluidic devices from borosilicate glass substrates. The fabrication method and applications of these devices for the investigation of subsurface flow processes in porous media are presented.