Channel Surface Research Articles

Heterostructured Ni2P/NiMo-layered double hydroxide nanoarrays with enriched redox active sites for supercapacitors

The electroactivity and cyclic stability of transition metal phosphides (TMPs) for supercapacitors are restricted by inadequate redox active sites and huge volume changes during the charging/discharging process. Herein, a three-dimensional (3D) porous Ni2P/NiMo-layered double hydroxide (NiMo-LDH) heterostructure with large specific surface and abundant pore channels is explored as a self-supporting supercapacitor electrode. The well-defined hierarchical pore structure can offer numerous electroactive sites and short ion/electron pathways. The generation of heterointerfaces between multi-dimensional Ni2P and two-dimensional (2D) NiMo-LDH nanosheets endows the hybrid composite with improved electrical conductivity and structural robustness. Consequently, the special nanoarchitecture design achieves a specific capacity of 198.6 mAh g−1 (2.28 mAh cm−2) at 1 A g−1 and an impressive rate performance of 78.3% at 20 A g−1. More importantly, the assembled Ni2P/NiMo-LDH//orange peel-derived porous carbon (OPC) asymmetric supercapacitor (ASC) device delivers a remarkable specific energy of 63.7 Wh kg−1 at a specific power of 1138.3 W kg−1 and long-term cycling stability (91.7% over 10,000 cycles). The research highlights that the hybridization of TMPs and other nanostructured battery-type materials may produce a synergistic effect and boost the capacitive properties.

Remote Sensing with UAVs for Flood Modeling: A Validation with Actual Flood Records

The use of unmanned aerial vehicles (UAVs) is steadily increasing due to their capacity to capture terrain elevation data with remarkable precision and cost-effectiveness. Nonetheless, their application for estimating water surface elevations and submerged terrain, such as channel bathymetry, remains constrained. Consequently, the development of a digital terrain model that relies on UAV data during low-water periods assumes a more extensive dry channel surface area, thus alleviating the information gap regarding submerged terrain. The objective of this brief report is to validate a hydraulic model for flood calculation. To this end, a 1D steady-state hydrological model of the Ñuble River based on a UAV survey in the low-water period of 2016 was constructed in HEC-RAS v.5.0.3 and compared to water surface elevation observations of the flood on 24 June 2023. The model tends to overestimate the flood, but the errors are considered tolerable for flood calculation (on average, a 10.6% depth error was obtained for a 30-year return period flood); therefore, the hydraulic model derived from remote sensing seems to be an effective alternative for the construction of hydraulic models for flood studies.

An unprecedented three-dimensional copper-halide-sulfur semiconductive framework for effective light and nitrogen dioxide electrical detections

The coordination of copper(I) halide moiety and sulfur-donor ligand to construct copper-halide-sulfur complex is proposed to combine the prominent optical and electronic functions from both copper halide and copper chalcogenide moieties. However, currently reported copper-halide-sulfur complexes mostly possess low dimensional structure or lack continuous electron transportation, thereby being unfavorable for electrical-based application. Herein, we report an unprecedented copper (I) complex {(pt)2Cu3I3}n (denoted as UJN-Cu6, pt = pyridin-1-ium-4-thiolate), which contains the first reported three-dimensional (3D) copper-halide-sulfur semiconductive framework. UJN-Cu6 was constructed by a deliberately synthesis strategy, where the copper iodine species were monodentate bridged by the sulfur-donor ligand, which is different from the most reported multidentate coordination mode. The thin film device of UJN-Cu6 can detect both UV and visible light with high switching on/off ratios and excellent photocurrent reproducibility. Further, the thin film device exhibits good sensitivity, short response time and high selectivity toward detecting hazardous NO2/N2O4. Mechanism studies indicate that the semiconductive copper-halide-sulfur skeleton contributes a lot to the electrical-based detection applications. The functional –N–H groups hanging on the surface of channel bring about highly selective recognition of NO2/N2O4 molecules.

Computer Modelling of Yarn Winding on Conical Bobbins

The article presents the results of the computer modelling of yarn winding on conical bobbins based on the analytical method of constructing tubular-shaped surfaces as a partial case of channel surfaces using the vector algebra apparatus. It is stated that the guide line takes the shape of a conical spiral line along which the forming moves (in the form of a circle with a diameter equal to the average diameter of the yarn), and is set using the moving Frenet basis. The obtained mathematical models facilitate the building, in MathCAD 3D visualization graphics, of a tubular-shaped surface, which represents the layers of yarn winding on a conical cartridge, and the reinforced yarn, which comprise the core component and the wrapping component, as well as the determination of both the lengths of individual layers of winding and the total length of winding (not including the transition sections). Well-known methods of forming geometric objects and computer modelling were also used in the work. The theoretical studies are based on the basic principles of textile production technology.

Tailoring Enantiomeric Chiral Channels in Metal-Peptide Networks: A Novel Foldamer-Based Approach for Host-Guest Interactions.

Designing chiral channels in organic frameworks presents an ongoing challenge due to the intricate control of size, shape, and functionality required. A novel approach is presented, which crafts enantiomeric chiral channels in metal-peptide networks (MPNs) by integrating short foldamer ligands with CuI clusters. The MPN structure serves as a 3D blueprint for host-guest chemistry, fostering modular substitution to refine chiral channel properties at the atomic scale. Incorporating hydrogen bond networks augments guest molecule interactions with the channel surface. This approach expedites enantiomer discrimination in racemic mixtures and incites adaptable guest molecules to take on specific axially chiral conformations. Distinct from traditional metal-organic frameworks (MOFs) and conventional reticular architectures, this foldamer-based methodology provides a predictable and customizable host-guest interaction system within a 3D topology. This innovation sets the stage for multifunctional materials that merge host-guest interaction systems with metal-complex properties, opening up potential applications in catalysis, sensing, and drug delivery.

Influence of injection methods on bio-mediated precipitation of carbonates in fracture-mimicking microfluidic chip

Enzymatically induced carbonate precipitation (EICP) is a potential method to alter the hydraulic properties of fractured rocks. The pore-scale in-situ formation of bio-mediated precipitated carbonates in fracture-mimicking channels was investigated experimentally through a visualization platform and microfluidic technology. Image processing was employed to analyze the precipitation behavior. Three representative biogrouting methods (one-phase continuous injection, one-phase staged injection, and two-phase staged injection) and the role of nucleation agents were examined in this study. Results revealed that more amorphous substances formed during one-phase injection process, and the one-phase staged injection method exhibited superior precipitation efficiency, while two-phase staged injection method demonstrated better effectiveness in channel clogging. The addition of nucleation agents resulted in the channel-like precipitation pattern, compared to formation of more crystals in the absence of additives. The hydrodynamic coupling between precipitation and flow velocity was used to explain the mechanisms of fracture sealing. Precipitation and aggregation led to the reduction in microchannel aperture, thereby influencing the flow field. Under flow-induced shearing, the amorphous substances could be transported and settled on the channel surface, leading to a self-enhancing process in channeling. This study provides insights into the microscopic mechanisms of EICP and advances the application of EICP in fracture repairing.

Physical insight into thermal analysis of magnetohydrodynamic stagnation point flow of micropolar nanofluid across a flexible surface equipped with porous medium and Fourier and Fick's law

AbstractNanofluids represent a novel heat transfer liquid, making them an efficient medium for enhancing energy transmission. Nevertheless, significant knowledge gaps still exist concerning current strategies for improving heat transfer in nanofluids, underscoring the necessity for comprehensive research on these fluid systems. Therefore, this study considered theoretical analysis retrieves the influence of radiative two‐dimensional stagnation point flow of second‐grade micropolar fluid flow about an elongated channel surface implanted in porous media with magnetic effect, and modified heat and mass flux is under consideration. The major novel effect of the current study is to analyze the activation energy and thermal aspect of the system in the presence of nonlinear radiation effects that are considered in the revised mathematical framework by utilizing the boundary layer theory. The resulting set of coupled partial differential equations is further reduced and transformed into a dimensionless system of ordinary differential equations through appropriate scaling invariants. We initiate the RKF‐45 investigation scheme to numerically analyze the transformed dimensionless system, considering relevant parameters. The computational algorithm is implemented using MATLAB programming syntax. Plotted visuals are revealed for leading parameters against pertinent flow profiles graphically and with numerical data. Additionally, the convergence analysis of the numerical results for various flow profiles of the fluids were compared to establish the authenticity of the proposed flow problem. These research findings play a significant role in controlling heat transfer rates and fluid velocities in diverse manufacturing processes and industrial applications, ultimately aiding in achieving the desired product quality.

Micro‐Patterning Wettability in Very Large Scale Microfluidic Integrated Chips for Double Emulsion Generation

AbstractThe fabrication of microfluidic chips is becoming a mature field and channels can be reliably defined with micrometer‐scale precision in a variety of substrates. In addition to channel geometry, micrometer‐scale patterning of wettability in microfluidic channels is essential for many applications including multi‐phase flow stabilization and multiple emulsion generation. Unfortunately, current methods to pattern wettability in microfluidics suffer from low spatial resolution, inability for patterns to be arbitrarily defined, cumbersome procedures, and incompatibility with parallelized architectures for scaled‐up production of microfluidic generated materials. To address these issues, a method is developed to lithographically define micrometer‐scale resolution patterns of wettability on all channel surfaces (ceiling, floor, and walls) in silicon and glass microfluidic devices with complex 3D geometry. A process is reported to pattern silanes on microfluidic chips that uses photolithography and an optimized process that keeps silanized surfaces stable through the microfabrication process, including anodic bonding. The versatility of this approach is highlighted by patterning wettability of a silicon/glass device to generate both highly uniform water–in‐oil–in‐water and oil–in‐water–in‐oil double emulsions. The applicability of this process is demonstrated to the parallel generation of materials in a microfluidic chip with complex geometry, by fabricating and successfully validating parallelized double emulsion generators.

Spontaneous Separation of Immiscible Organic Droplets on Asymmetric Wedge Channels with Hierarchical Microchannels.

Spontaneous separation of immiscible organic droplets has substantial research implications for environmental protection and resource regeneration. Compared to the widely explored separation of oil-water mixtures, there are fewer reports on separating mixed organic droplets on open surfaces due to the low surface tension differences. Efficient separation of mixed organic liquids by exploiting the rapid spontaneous transport of droplets on open surfaces remains a challenge. Here, through the fusion of inspiration from the fast droplet transport capability of Sarracenia trichome and the asymmetric wedge channel structure of shorebird beaks, this work proposes a spine with hierarchical microchannels and wedge channels (SHMW). Due to the synergistic effect of capillary force and asymmetric Laplace force, the SHMW can rapidly separate mixed organic droplets into two pure phases without requiring additional energy. In particular, the self-spreading of the oil solution on the open channel surface is utilized to amplify the surface energy difference between two droplets, and SHMW achieves the pickup of oil droplets floating on the surface of the organic solution. The maximum separation efficiency on 3-SHMW can reach 99.63%, and it can also realize the antigravity separation of mixed organic droplets with a surface tension difference as low as 0.87 mN·m-1. Furthermore, SHMW performs controllable separation, oil droplet pickup, and continuous separation and collection of mixed organic droplets. It is expected that this cooperative structure composed of hierarchical microchannels and wedge channels will be realized in resource recovery or chemical reactions in industrial production processes.

Chitosan modified graphene field-effect transistor biosensor for ultrasensitive procalcitonin detection

Sepsis is a systemic inflammatory response caused by a bacterial infection that often leading to tissue damage, organ failure and death. Procalcitonin (PCT), as a peptide precursor to hormones, is the main biomarker to identification of the sepsis. In this study, a chitosan modified graphene field transistor (CTS-GFET) was established and first time used for PCT ultra-sensitive detection. CTS was functionalized on the GFET channel surface to immobilized anti-PCT by glutaraldehyde. This biosensor exhibited the detection limit as low as 0.82 ag/mL in PBS, which exhibited 3 times enhancement compared with GFET biosensors. The enhancement mechanisms of CTS-GFET were studied by electrical theoretical model. In addition, the CTS-GFET biosensor was successfully applied to quantify the concentration of the PCT in human serum samples, indicating the potential use in clinical application.

Surface absorption channels in light absorption by a 2D-material-coated particle

Light absorption enhancement in micro- and nanoparticles has garnered considerable attention through coated 2D materials, which are physically homogenized by surface conductivities and surface currents within the electromagnetic boundary conditions. However, the electromagnetic absorption through the surface channel remains unexamined, hindering a deeper understanding of the underlying mechanisms of light absorption. In this work, we analytically derive the effective cross sections of surface absorption for a 2D-material-coated sphere, based on the framework of Mie theory amended by the surface conductivity. Our theoretical analysis confirms the absorption unitarity in wrapped particles, whereby the total absorption is equivalent to the sum of surface and volume absorptions. Considering optical dispersion of a polar interior, we identify a blue shift in the resonance wavelength induced by the 2D coating, which leads to a decrease in material dissipation and thus volume absorption within the particle itself in spite of a large field enhancement inside the particle. Finally, through a realistic case of small graphene-wrapped MgO spheres, we illustrate the dominant role of the surface absorption channel on the mechanism of absorption enhancements.

Digital Manufacturing of Functional Ready-to-Use Microfluidic Systems.

Digital manufacturing (DM) holds great potential for microfluidics, but requirements for embedded conduits and high resolution beyond the capability of common manufacturing equipment, and microfluidic systems' dependence on peripheralshave limited its adoption. Capillaric circuits (CCs) are structurally encoded, self-contained microfluidic systems that operate and self-fill via precisely tailored hydrophilicity. CCs are heretofore hydrophilized in a plasma chamber, but which offers only transient hydrophilicity, lacks reproducibility, and limits CC design to open surface channels subsequently sealed with tape. Here, the additive DM of monolithic, fully functional, and intrinsically hydrophilic CCs is reported. CCs are 3D printed with commonly available light-engine-based 3D printers using poly(ethylene glycol)diacrylate-based ink co-polymerized with hydrophilic acrylic acid crosslinkers and optimized for hydrophilicity and printability. A new, robust capillary valve design and embedded conduits with circular cross-sections that prevent bubble trapping are presented, interwoven circuit architectures created, and CC use illustrated with an immunoassay. Finally, the external paper capillary pumps are eliminated by directly embedding the capillary pump in the chip as a porous gyroid structure, realizing fully functional, monolithic CCs. Thence, a digital file can be made into a CC by commonly available 3D printers in less than 30min enabling low-cost, distributed DM of fully functional ready-to-use microfluidic systems.

Label free optofluidic DNA hybridization detection based on suspended core fiber whispering gallery mode resonator

An optofluidic DNA biosensor based on a suspended core fiber (SCF) has been proposed for the detection of specific DNA sequence fragments. The sensor is formed by coupling a micro/nano tapered optical fiber to the cladding of an SCF, producing a whispering gallery mode (WGM) effect. The WGM resonance is sensitive to samples within the channels of the SCF. The diameter of the SCF is reduced by etching to increase refractive index sensitivity, up to 274 nm/RIU. Biomarkers are captured on the inner surface of the microfluidic channel leading to a change in the local refractive index. The experimental results show that the sensor can quantitatively detect complementary DNA (cDNA) by immobilizing probe DNA (pDNA) on the surface of the microfluidic channel with a limit of detection of 1.5 nM. The proposed DNA biosensor provides a label-free method for DNA detection, which has great potential for multiplexed detection and realizing disease diagnostics.

Iron ions embedded in hexagonal mesoporous silica via a simple method: implementation in mild oxidation catalysis

AbstractMesoporous silica monoliths containing dispersed FeIII sites have been prepared following a direct and simple synthetic method. The iron‐containing materials are able to catalyze the epoxidation of cyclooctene by H2O2 under mild conditions. Textural and spectrophotometric analyses reveal that, when the thermal treatment temperature of the materials increases (from 500 °C to 1000 °C), the pore diameter of the silica matrix decreases while the formation of small oxo‐iron(III) clusters is promoted. Among the five materials obtained after treatment at 500, 700, 800, 900 or 1000 °C, the one prepared at 700 °C exhibits the best catalytic performances. This indicates that a compromise must be found between several parameters, such as the pore size (which decreases with calcination temperature) and the hydrophobicity of the channel surface (which is favored at higher temperature), for an optimal reactivity.

Dopamine-Regulated Plasticity in MoO3 Synaptic Transistors.

Field-effect transistor-based biosensors have gained increasing interest due to their reactive surface to external stimuli and the adaptive feedback required for advanced sensing platforms in biohybrid neural interfaces. However, complex probing methods for surface functionalization remain a challenge that limits the industrial implementation of such devices. Herein, a simple, label-free biosensor based on molybdenum oxide (MoO3) with dopamine-regulated plasticity is demonstrated. Dopamine oxidation facilitated locally at the channel surface initiates a charge transfer mechanism between the molecule and the oxide, altering the channel conductance and successfully emulating the tunable synaptic weight by neurotransmitter activity. The oxygen level of the channel is shown to heavily affect the device's electrochemical properties, shifting from a nonreactive metallic characteristic to highly responsive semiconducting behavior. Controllable responsivity is achieved by optimizing the channel's dimension, which allows the devices to operate in wide ranges of dopamine concentration, from 100 nM to sub-mM levels, with excellent selectivity compared with K+, Na+, and Ca2+.

Effect of Surface Roughness and Channel Slope on Hydraulic Jump Characteristics: An Experimental Approach Towards Sustainable Environment

Effect of Surface Roughness and Channel Slope on Hydraulic Jump Characteristics: An Experimental Approach Towards Sustainable Environment

Discretized and experimental investigation of thermo-hydraulic behavior in a compact heat exchanger manufactured via SLM process

The demand for a better understanding of the fluid thermal and hydrodynamic behavior along the heat exchanger makes it necessary to develop a discretized analysis. The temperature and pressure distributions from the local analysis allow the obtaining of mechanical and thermal stress fields, making the method advantageous in comparison to the conventional global analysis. This work developed a local thermo-hydraulic model for a compact heat exchanger manufactured via Selective Laser Melting (SLM) process. The cross-flow heat exchanger core, produced with American Iron and Steel Institute (AISI) 316L, has 100 mm height, 100 mm width, 100 mm length, and a 2 mm channel diameter. The local steady-state models were compared with experimental data. The experiments were performed with water on both sides, using different temperatures for the hot side, and Reynolds numbers ranging from 1748 to 12247. The local analytical models have a good agreement, with 14% average errors for the thermal and hydrodynamic models. Besides, the impacts of channel diameter and surface roughness in the pressure drop were studied.

Label-Free Chemiresistive Sensors Based on Self-Assembled Ti3C2Tx MXene Films for Monitoring of Microcystin-LR in Water Samples.

Herein, we propose a label-free chemiresistive sensor for the highly sensitive and selective detection of microcystin (MC)-LR in water samples. The sensor uses a layer-by-layer (LBL) assembled conductive film consisting of Ti3C2Tx nanosheets as the sensing channel. It is further modified by using an aptamer for the specific recognition of MC-LR. The response signal is based on the change in resistance of the conductive channel upon binding of MC-LR with the aptamer. Our novel strategy is the first concept proposed for immobilizing the aptamer containing -SH on the channel surface through a Ti-S bond under weakly alkaline condition. The resulting sensor is highly sensitive and stable for the detection of MC-LR, with a detection limit of 0.18 ng L-1 and a wide linear range from 1 to 104 ng L-1. We used the sensor to continuously monitor MC-LR released by cultivated Microcystis aeruginosa, showing a strong relationship between MC-LR and cell density. Furthermore, the sensor was successfully used to measure MC-LR in freshwater lakes with moderate algal blooms, and the results agreed well with those obtained by liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. The present study provides a reliable method for highly sensitive and selective detection of MC-LR in environmental waters.

Thermodynamic Performance Enhancement of an Air Conditioner With Dew Point Evaporative Cooler

Abstract The vapor-compression-based conventional split air conditioners (CACs) consume a large portion of total electrical power and pose an alarming threat to global environment. The present work aims to reduce cooling load and power consumption of CAC by employing a dew point evaporative cooler (DPEC). DPEC consists of a counter flow type heat and mass exchanger with alternate layers of dry and wet channels. The intake air is sensibly cooled before entering the cooling room through the evaporator coil of the air conditioner. Also, the working air (a part of outlet air in dry channel), after absorbing sensible heat of intake air and water vapors from the wet channel surface, is allowed to pass across the condenser coils. The intake dry-bulb temperature (T0 = 29–44 °C) and specific humidity (ω0 = 6–22 g/kg) are taken as input parameters. While the cooled air entering the evaporator decreases the cooling load on the conditioned space, the compression work is also reduced due to increased heat transfer in the condenser. The maximum reductions in cooling load and monthly energy consumption at T0 = 44 °C and ω0 = 6 g/kg are found as 59.54% and 340 kW h, respectively. The water consumption for different months of the cooling season varies from 1037.8 L to 2905.95 L. The average energy savings with the DPEC system for hot-dry climate (from April to June) and hot-humid climate (from July to September) of New Delhi, India, are observed to be 479.6 kW h and 79.1 kW h, respectively. The proposed system is found to payback in about 3.37 years.

Surface-modified microchip electrophoretic separation and analysis of functional components in health care products

Microchip electrophoresis (MCE) is widely applied in food, environment, medicine, and other fields, owing to its high separation efficiency, low consumption of reagents and samples, and ease of integrating multiple operating units. Polymer microchip materials like cycloolefin copolymer (COC) are low-cost and easy to fabricate. However, their practical applications are limited by the non-specific adsorption on channel surface during electrophoresis and the instability of electroosmotic flow. These shortcomings can be solved by COC surface modification. In this study, a static coating and dynamic/static coating combined strategy was used to develop a channel-surface-modified COC microchip. Combined with laser-induced fluorescence (LIF) detection, a MCE-LIF separation and analysis method was developed for detecting functional components in health care products. The separation performance of MCE was improved by the static coating microchannel surface modification method. The static coating was constructed by hydrophobic amino acid adsorption, glutaraldehyde immobilization, and hydrophilic amino acid functionalization on the COC microchannel surface. The separation performance of MCE was improved by microchannel surface modification combined with dynamic/static coating. The static coating was constructed by valine adsorption, carboxyl activation, and ethylenediamine functionalization on the COC microchannel surface. The dynamic coating is automatically formed by introducing a buffer solution containing hydroxypropyl methylcellulose and sodium dodecyl sulfate into the microchannel. The physical and chemical properties of surface-modified microchannels and the factors governing electrophoretic separation were studied. Combined with LIF detection, the MCE-LIF separation and analysis of lysine and γ-aminobutyric acid present in children's health care products, as well as aspartic acid and taurine in sport drinks, were developed. The recoveries of lysine and γ-aminobutyric acid in children's health care products were 84.8%-118%, and the relative standard deviations (RSDs) were less than 7.2% (n=3). The recoveries of aspartic acid and taurine in sport drinks were 97.5%-118%, and the RSDs were less than 6.4% (n=3). The analysis results are consistent with the HPLC results, and the method has potential for application in the separation and analysis of anionic amino acids in health care products.