Liquid Layer Research Articles

Electrochemical Sensing of Triazole Drugs based on Carbon Based Nanocomposites: A Review

India is the nation with international boarder wherein a huge number of soldiers are deployed. Fungal infections are a common complaints suffered by military personnel at warm, damp or wet environments. Anti-fungal drugs have their application in the treatment of fungal infections. They do so by either killing or controlling the fungi in the host with low toxicity. The Heterocyclic compounds with triazole linkages are known for their effective anticancer and antifungal properties. The sensitive, robust, reproducible quantification of triazole can take place at fast rates without any involvement of multiple steps of sample preparation. This is all possible because of the electrochemical activity of the triazole. There has been a significant increase in Carbon-based nanomaterials being preferred for sensor materials development. The properties of Carbon-based nanomaterials such as inherent electrical conductivity, chemical stability, strong adsorption capacity, and good biocompatibility are what make it preferable. The materials with these properties include an array of carbon compounds such as carbon nanotubes (CNTs), fullerenes, carbon nanofibers, carbon black, etc. CNTs are often counted in the list of important carbonaceous materials and they're also suitable for the fabrication of the electrodes. This is possible because of its high surface area, and good electrical properties. The materials based on CNTs are used to produce sensors that are hybrid in nature, drug delivery, and high-performance composites for plants to identify pathogens. Methods based on high performance liquid and thin layer chromatography, gas chromatography and spectrophotometry involves a series of sample preparations and are executed over costly equipments. Owing to numerous advantages such as rapid response, high performance, cost effective, high sensitivity and selectivity, electrochemical sensors became increasingly promising tool over other conventional analytical methods. Nanohybrid based electrochemical sensor is used for trace level estimation of triazole drugs in pharmaceutical dosage and biological samples.

The influence of the liquid layer height on the velocity field and evaporation during local heating

ABSTRACT The Particle Image Velocity method was used to investigate the velocity fields when the liquid layer height changed from 0.6 to 5.1 mm. The loss of stability of the velocity field during local heating is realized at the Bond number (Bo) 0.01–0.02, which is 10–20 times lower than the critical value of Bo(cr) compared to heat exchange at a uniform wall temperature. The Marangoni flow depends both on the height and the layer diameter. The critical height of the layer 2–2.5 mm leads to a sharp change in the flow pattern.

Mixed convection flow of lower convected second grade with unsteady MHD nanofluid over a stretching surface in porous medium

This paper presented an analysis for time-varying nanofluid thin liquid layer applied over a stretched heated plate with adjustable concentration and temperature. The governing partial differential equations of problem have been reduced to similar ordinary differential equations through similarity transformation using group theoretic method those are convenient to find solutions along with numerical solution. Analysis comprises for impact of various parameters as Prandtl number Pr, Schmidt number Sc, Thermal exponent r, Concentration exponent s, Deformation rate [Formula: see text], Thermophoresis parameter [Formula: see text], & Brownian motion parameter [Formula: see text], on auxiliary variables like Velocity [Formula: see text], Temperature [Formula: see text] and Concentration [Formula: see text]. The MATHEMATICA software is used to solve and extract graphs for problem. The results have been depicted via graphs to grasp conclusive declaration.

Heat transfer effects on the oscillatory MHD flow in a porous channel with two immiscible fluids

The MHD oscillatory flow of two immiscible, viscous liquids in a porous channel with heat transfer is the subject of this investigation. The two liquid layers with different viscosities flow in both regions. The analytical expressions for velocity and temperature distribution have been derived by solving the governing flow equations using the regular perturbation method. The effects of various parameters on the velocity, temperature, and Nusselt number have been shown graphically, and numerical values of skin friction and flow rate are presented in tabular form and discussed. According to our analysis, the mass flux reduces as the magnetic field strength rises. While the temperature of the liquid enhances with an increase in the Eckert number and the Prandtl number, the temperature distribution rises with a decrease in the thermal conductivity ratio. To validate the results, the analytical solutions are compared with the fourth-order numerical Runge–Kutta method coupled with the shooting approach, and the results are found to be in excellent agreement.

Wave propagation in a circular channel: sloshing and resonance

Surface wave resonance of a liquid (water) layer confined in a circular channel is studied both experimentally and numerically. For the experiment, eight unevenly distributed ultrasonic distance sensors measure the local height of the wave surface. The resonance curves show maxima only for odd multiples of the fundamental resonance frequency f_0. We explained this behavior using a simple intuitive “ping-pong” like model. Collision of wave fronts can be observed for higher frequencies. Also, the wave reflection on the walls can be treated as wave collision with itself. The non-linearity seems to be weak in our study so the delay in the wave propagation before and after the collision is small. Time-space plots show localized propagating waves with high amplitudes for frequencies near resonance. Between the peaks low amplitude and harmonic patterns are observed. However, for higher frequencies, the frequency band for localized waves becomes wider. In the Fourier space-time plane, this can be observed as a point for the harmonic patterns or a superposition of two lines: one line parallel to wave-vector k axis corresponding to the excitation frequency f_0 and a second line with inclination given by wave propagation velocity sqrt{gh}. For planned future work, this result will help us to reconstruct the whole water surface elevation using time-series from only a few measurement points

Microfluidic Transport in Ternary Liquid Layers Due to Sinusoidal Thermocapillary Actuation

Abstract The large-scale applicability of the micro- and nanofluidic devices demands continuous technological advancements in the transport mechanisms, especially to promptly mix the analytes and reagents at such a small scale. To this end, thermocapillarity-induced Marangoni hydrodynamics of three-layered, immiscible fluid streams in a microchannel is analytically explored. The system is exposed to periodic and sinusoidal thermal stimuli, and a theoretical framework is presented. The diffusion of the periodic thermal stimuli across and along the fluidic interfaces creates axial surface tension gradients, which induce vortical motion of the participating fluids within the microconduit. We show that depending on the physical parameters of the three participating fluids, such vortex patterns may be fine-tuned and controlled to obtain desired transport behavior. An analytical solution for the thermal and the hydrodynamic transport phenomena is obtained by solving the momentum and energy conservation equations under the umbrella of creeping flow characteristics (very low Reynolds and thermal Marangoni numbers), and nearly undeformed fluid interfaces (negligibly small Capillary number). The approximate profiles of the deformed interfaces are also quantified theoretically to justify the assumption of flat and undeformed interfaces. The independent influence of crucial thermophysical properties, the microchannel system parameters, and features of the applied thermal stimuli are shown in detail for a fixed combination of other parameters.

Plant growth and early in vitro floral differentiation of vanilla (Vanilla planifolia Jacks. ex Andrews)

Objective: To induce in vitro flowering of vanilla (Vanilla planifolia) with different plant growth regulators (PGRs) using the double-layer technique. Design/methodology/approach: A layer of semi-solid Knudson C (KC) medium, added with 40 g L-1 sucrose, 15% coconut water (CW; v/v) and 7 g L-1 agar, was placed in 100 mL flasks. A liquid layer of the same composition without agar was placed on top. It was supplemented with different doses (mg L-1) of PGRs: 6-benzyladenine (BA) (7), thidiazuron (TDZ) (6), paclobutrazol (PBZ) (0.5) and gibberellic acid (AG3) (2). Plus two controls, C1: no PGRs + no CW; C2: no PGRs + CW. Vanilla shoots of 2 cm in length and with at least one axillary shoot were placed. They were incubated at a temperature of 26±2 °C day and 18 °C darkness, with light intensity of 55 µmol m-2 s-1 during 13 weeks. The number of shoots, leaves and roots was evaluated, as well as the length of shoots and fresh weight. Floral differentiation was evaluated at the tenth week by conventional microtechnique. Results: The number shoots and leaves and shoot length were significantly higher in C2. The number of roots increased with PBZ 0.5 mgL-1. C1 and C2 promoted higher fresh weight. Floral differentiation was observed with AG3 2 and PBZ 0.5 mg L-1 treatments. Limitations on study/implications: Further evaluation of other PGR doses and environmental conditions is required to achieve full floral differentiation of vanilla. Findings/conclusions: CW increased vegetative growth. AG3 and PBZ showed early floral differentiation in Vanilla planifolia, which is the first report of this phenomenon for the species.

Generalized Poro-thermoelastic Waves in the Cylindrical Plate Framed with Liquid Layers

Generalized Poro-thermoelastic Waves in the Cylindrical Plate Framed with Liquid Layers

Evaporating Rayleigh–Bénard convection: prediction of interface temperature and global heat transfer modulation

We propose an analytical model to estimate the interface temperature $\varTheta _{\varGamma }$ and the Nusselt number $Nu$ for an evaporating two-layer Rayleigh–Bénard configuration in statistically stationary conditions. The model is based on three assumptions: (i) the Oberbeck–Boussinesq approximation can be applied to the liquid phase, while the gas thermophysical properties are generic functions of thermodynamic pressure, local temperature and vapour composition, (ii) the Grossmann–Lohse theory for thermal convection can be applied to the liquid and gas layers separately and (iii) the vapour content in the gas can be taken as the mean value at the gas–liquid interface. We validate this setting using direct numerical simulations in a parameter space composed of the Rayleigh number ( $10^6\leq Ra\leq 10^8$ ) and the temperature differential ( $0.05\leq \varepsilon \leq 0.20$ ), which modulates the variation of state variables in the gas layer. To better disentangle the variable property effects on $\varTheta _\varGamma$ and $Nu$ , simulations are performed in two conditions. First, we consider the case of uniform gas properties except for the gas density and gas–liquid diffusion coefficient. Second, we include the variation of specific heat capacity, dynamic viscosity and thermal conductivity using realistic equations of state. Irrespective of the employed setting, the proposed model agrees very well with the numerical simulations over the entire range of $Ra$ – $\varepsilon$ investigated.

Mini Bénard-Marangoni cells floating over thermocapillary flow in evaporative thin liquid layers

The Marangoni convection instability patterns were experimentally investigated in evaporating thin rectangular liquid layers and a kind of mini cells were found in the layers. Although the geometrical size of the mini cells is quite smaller than the classical Bénard-Marangoni (BM) cell, they actually belong to a kind of BM cells according to their behaviors and characteristics. They floated on the upper portion of the layer but did not penetrate the entire thickness of layer. The mini cells were generated in a basically flow layer, i.e., the horizontal thermocapillary flow caused by evaporation. They moved along the basic thermocapillary flow from endwalls to the central area of liquid layers. The stagnant points of the mini cells deflected the opposite direction of cells motion. The wavelength, penetration depth, and the movement speed of the mini cells were measured. The critical horizontal Marangoni number for the incipience of the mini cells were determined and the mechanisms were analyzed carefully.

Experimental and LBM simulation study on the bubble dynamic behaviors in subcooled flow boiling

Bubble dynamic behavior is a fundamental issue in comprehending flow boiling process. In this paper, the bubble characteristics are studied in depth through experiment in conjunction with the Lattice Boltzmann method (LBM). Firstly, the visualized experiment in rectangular channels with double heating plates is performed during subcooled flow boiling. High-speed camera is employed to directly capture the macroscopic bubble dynamic behaviors under different working conditions. Furthermore, LBM model with a novel hybrid boundary scheme is developed to investigate mesoscopic bubble characteristics, including contact diameter, microlayer thickness profile and superheated layer thickness. The bubble diameter from LBM model is compared to experimental data with a mean relative error of 10.8%. The results of the current research find that the bubbles nucleating on the inside channel have smaller contact diameter ratio and larger inclined angle. Finally, combining macroscopic experiments and mesoscopic LBM studies, a model of the bubble growth rate is proposed for predicting bubble growth behavior. In the process of model development, three aspects for deciding the bubble growth rate are considered, including microlayer evaporation, heat diffusion from the superheated liquid layer, and condensation at bubble dome caused by subcooled flow boiling. The prediction model agrees well with the experimental results, with a mean relative error of 14.7%. The established bubble growth model will help to predict the heat transfer process during flow boiling.

Ultrahigh Lubricity between Two-Dimensional Ice and Two-Dimensional Atomic Layers.

Low temperature and high humidity conditions significantly degrade the performance of solid-state lubricants consisting of van der Waals (vdW) atomic layers, owing to the liquid water layer attached/intercalated to the vdW layers, which greatly enhances the interlayer friction. However, using low temperature in situ atomic force microscopy (AFM) and friction force microscopy (FFM), we unveil the unexpected ultralow friction between two-dimensional (2D) ice, a solid phase of water confined to the 2D space, and the 2D molybdenum disulfides (MoS2). The friction of MoS2 and 2D ice is reduced by more than 30% as compared to bare MoS2 and the rigid surface. The phase transition of liquid water into 2D ice under mechanical compression has also been observed. These new findings can be applied as novel frictionless water/ice transport technology in nanofluidic systems and promising high performance lubricants for operating in low temperature and high humidity environments.

Enhanced Stability of Atomically Dispersed Pd Catalysts via Ionic Liquid Layer Deposition for Selective Acetylene Hydrogenation to Ethylene in Excess Ethylene

AbstractA series of TiO2‐supported Pd catalysts with different amounts of ionic liquid (IL) were synthesized for the selective hydrogenation of acetylene to ethylene in excess ethylene. CO Fourier transform infrared spectroscopy (FTIR), high‐angle annular dark‐field‐scanning transmission electron microscopy (HAADF‐STEM), and X‐ray photoelectron spectroscopy (XPS) suggested that the Pd species in the catalysts synthesized via the strong electrostatic adsorption (SEA) method exist predominantly as isolated atoms on TiO2 independent of the presence of the IL. Using a combination of FTIR and XPS, it was found that IL deposition on Pd catalysts induces a change in the electronic structure of atomically dispersed Pd atoms. The IL‐modified catalysts exhibited improved stability in acetylene hydrogenation compared to IL‐free catalysts owing to their higher coke resistance. Thus, this study provides a novel synthetic strategy based on IL deposition for improving the coke resistance and stability of atomically dispersed catalysts.

Spectroscopic Detection of Biosignatures in Natural Ice Samples as a Proxy for Icy Moons.

Some of the icy moons of the solar system with a subsurface ocean, such as Europa and Enceladus, are the targets of future space missions that search for potential extraterrestrial life forms. While the ice shells that envelop these moons have been studied by several spacecrafts, the oceans beneath them remain unreachable. To better constrain the habitability conditions of these moons, we must understand the interactions between their frozen crusts, liquid layers, and silicate mantles. To that end, astrobiologists rely on planetary field analogues, for which the polar regions of Earth have proven to be great candidates. This review shows how spectroscopy is a powerful tool in space missions to detect potential biosignatures, in particular on the aforementioned moons, and how the polar regions of the Earth are being used as planetary field analogues for these extra-terrestrial environments.

M6A-ELISA, a simple method for quantifying N6-methyladenosine from mRNA populations.

N6-methyladenosine (m6A) is a widely studied and abundant RNA modification. The m6A mark regulates the fate of RNAs in various ways, which in turn drives changes in cell physiology, development, and disease pathology. Over the last decade, numerous methods have been developed to map and quantify m6A sites genome-wide through deep sequencing. Alternatively, m6A levels can be quantified from a population of RNAs using techniques such as liquid chromatography-mass spectrometry or thin layer chromatography. However, many methods for quantifying m6A levels involve extensive protocols and specialized data analysis, and often only a few samples can be handled in a single experiment. Here, we developed a simple method for determining relative m6A levels in mRNA populations from various sources based on an enzyme-linked immunosorbent-based assay (m6A-ELISA). We have optimized various steps of m6A-ELISA, such as sample preparation and the background signal resulting from the primary antibody. We validated the method using mRNA populations from budding yeast and mouse embryonic stem cells. The full protocol takes less than a day, requiring only 25 ng of mRNA. The m6A-ELISA protocol is quick, cost-effective, and scalable, making it a valuable tool for determining relative m6A levels in samples from various sources that could be adapted to detect other mRNA modifications.

High-Throughput Fabrication of Size-Controlled Pickering Emulsions, Colloidosomes, and Air-Coated Particles via Clog-Free Jetting of Suspensions.

Microcapsules with a liquid core and a solid shell composed of hydrophobic nanoparticles are broadly applied in food, pharmaceutics, and biotechnologies. For example, Pickering emulsions, colloidosomes, or antibubbles (droplets surrounded by air layers in water) enable controlled release of active agents, biocompatibility, and contact-less liquid transportation. However, producing controlled nanoparticle- or polymer-laden hydrophobic shells at scale is highly challenging, since bulk methods are polydisperse and microfluidic chips are prone to clogging and slow. Here, clog-free coating of an aqueous jet with silica nanoparticle suspensions with concentrations up to 10% (w/v), as well as high concentrations of polymers (30% (w/v) poly(lactic acid) (PLA)), is demonstrated, enabling continuous generation of microcapsules at flow rates up to 4mLmin-1 . Pickering emulsions are converted into capsules, providing hydrophobic shells consisting of nanoparticles for controlled release. As a highlight, the scalable fabrication ofair-coated capsules (antibubbles) in the sub-millimeter range is demonstrated. The shell contains an air film that protects the liquid core for days yet enables ultrasound-induced release within 3 min. By enabling rapid fabrication of controlled Pickering emulsions, colloidosomes, antibubbles, and biodegradable capsules, jetting through a liquid layer (JetALL) provides a versatile platform for advanced applications in food, pharmacy, and life science.

Morphology evolution of a melting solid layer above its melt heated from below

We numerically study the melting process of a solid layer heated from below such that a liquid melt layer develops underneath. The objective is to quantitatively describe and understand the emerging topography of the structures (characterized by the amplitude and wavelength), which evolve out of an initially smooth surface. By performing both two-dimensional (achieving Rayleigh number up to$Ra=10^{11}$) and three-dimensional (achieving Rayleigh number up to$Ra=10^9$) direct numerical simulations with an advanced finite difference solver coupled to the phase-field method, we show how the interface roughness is spontaneously generated by thermal convection. With increasing height of the melt the convective flow intensifies and eventually even becomes turbulent. As a consequence, the interface becomes rougher but is still coupled to the flow topology. The emerging structure of the interface coincides with the regions of rising hot plumes and descending cold plumes. We find that the roughness amplitude scales with the mean height of the liquid layer. We derive this scaling relation from the Stefan boundary condition and relate it to the non-uniform distribution of heat flux at the interface. For two-dimensional cases, we further quantify the horizontal length scale of the morphology, based on the theoretical upper and lower bounds given for the size of convective cells known from Wanget al.(Phys. Rev. Lett., vol. 125, 2020, 074501). These bounds agree with our simulation results. Our findings highlight the key connection between the morphology of the melting solid and the convective flow structures in the melt beneath.

Floating Liquid Droplets on the Surface of Cryogenic Liquids: Implications for Titan Rain.

Saturn's moon, Titan, has a hydrocarbon-based hydrologic cycle with methane and ethane rainfall. Because of Titan's low gravity, "floating liquid droplets" (coherent droplets of liquid hydrocarbons that float upon a liquid surface) may form on the surface of Titan's hydrocarbon lakes and seas during rainfall. Floating liquid droplets, however, have not been investigated in the laboratory under conditions appropriate for the surface of Titan (cryogenic, hydrocarbon, liquids). We conducted a set of experiments to simulate methane and ethane rainfall under Titan surface conditions (89-94 K, 1.5 bar nitrogen atmosphere) and find that floating ethane droplets form in a wide range of bulk liquid compositions, yet floating methane droplets only form in a narrow compositional range and impact velocity. We find droplet formation is independent of the liquid density and hypothesize that dissolved atmospheric nitrogen in the bulk liquid may repel liquid ethane droplets at the surface. We propose that liquid droplets will form in Titan's methane-rich lakes and seas during ethane rainfall with a droplet radius of ≤3 mm and an impact velocity of ≤0.7 m/s. The presence of these droplets on Titan's lakes may result in a liquid surface layer that is dominated in rainfall composition.

Construction of robust slippery lubricant-infused epoxy-nanocomposite coatings for marine antifouling application

From an environmental perspective, slippery liquid-infused porous surface (SLIPS) have great potential to substitute for traditional antifouling coatings due to their green and broad-spectrum antifouling properties. However, the complicated strategy curbs its forward application. In this study, the superhydrophobic surfaces (SHS) was constructed by an air spraying method via solution blending, with epoxy resin and hydroxyl-terminated polydimethylsiloxane as the matrix and nano titanium dioxide particles as the filler. Then, silicone oil with different viscosities were infused into the SHS to form SLIPS. Experiments of simulated fluid erosion in a marine environment showed that silicone oil with 500 mPa·s maintained a contact angle hysteresis (CAH) of 6.9° with good liquid-repellency performance after 12 h of scouring，while the silicone oil with lower viscosity loosed the liquid-repellency performance. Antifouling test results showed that SLIPS had excellent antifouling performance, and the antifouling rates of against Phaeodactylum tricornutum and Bacillus sp. were 90.8 % and 93.6 %, respectively. Thermodynamic analysis showed that the air layer of SHS coating and the liquid layer of SLIPS played a vital role in antifouling performance, which coincided with antifouling experimental results. The efficient and environment-friendly coating preparation method was used in this study will provide reference value and theoretical basis for the application of SLIPS in the field of marine antifouling.

An optimize empirical correlations for liquid film thickness and interfacial friction factor in vertical gas-liquid annular flow

BackgroundThe annular flow regime is one of the most prevalent two-phase flow regimes, occurring throughout a broad range of gas and liquid flow rates. This flow pattern is distinguished by a thin layer of liquid around the walls and a core of quickly flowing gas in the middle. MethodsUsing image recording and processing methods, the generation of an annular flow pattern in a counter-current two-phase flow in a vertical transparent pipe was explored in the current experimental study. In this regard, the range of air (bottom to top) and water (top to bottom) velocities for annular flow was 20.94–3.66 m/s and 0.3–1.06 m/s, respectively. Significant findingsIn this paper, the liquid film thickness is provided as a novel five-variable correlation function of gas phase superficial velocity, liquid phase velocity, pipe diameter, Weber number, and Froude number, with an R2 value of 0.98. In addition, the interfacial friction factor (liquid and gas phases) is provided as a five-variable correlation based on gas flow Reynolds number, liquid flow Reynolds number, pipe diameter, liquid film thickness, and Froude number with coefficient of determination of 0.97. The sensitivity analysis of the acquired experimental findings reveals that the liquid film thickness and the interfacial friction factor are most sensitive to changes in the superficial velocity of the gas phase and the Reynolds number of the liquid phase, respectively. Also, for the thickness of the liquid film and the interfacial friction coefficient, the experimental values and suggested correlations deviate by a maximum of 3.15 percent and 4.56 percent, respectively.