Microscale Pores Research Articles

Influence of shale bedding on development of microscale pores and fractures

The characteristics of bedding development have an important impact on the spatial distribution of shale pores and fractures. However, there is a lack of systematic study on the pore and fracture structure of bedding development characteristics. In this paper, the geological control mode of shale type on the development characteristics of pores and fractures is revealed; pore-throat models under different shale lithology conditions are constructed; the control mechanism of bedding development characteristics on the spatial distribution pattern of pores and fractures is clarified. Results show that: (a) The pore space size varies widely from nanoscale to micron-scale or even millimeter scale, and is mainly concentrated in the nanoscale range. (b) For shale samples No. 1-7-1 No. 21-7-1, although the proportion of organic matter and mineral area in different samples varies greatly, the difference between the proportion of organic pore area and the proportion of mineral pore area is not significant, and the proportion of organic pore area is much higher than that of mineral pore area. (c) The pore diameter of shale has strong heterogeneity; minerals have an important impact on throat diameter; maturity has an important impact on throat length; geological compaction and tectonism will have an impact on the tortuosity of shale reservoir pores; the controlling effect of pore connectivity on shale wettability is mainly reflected in the connectivity of hydrophilic and lipophilic pores.

Self-regulated underwater phototaxis of a photoresponsive hydrogel-based phototactic vehicle.

Incorporating a negative feedback loop in a synthetic material to enable complex self-regulative behaviours akin to living organisms remains a design challenge. Here we show that a hydrogel-based vehicle can follow the directions of photonic illumination with directional regulation inside a constraint-free, fluidic space. By manipulating the customized photothermal nanoparticles and the microscale pores in the polymeric matrix, we achieved strong chemomechanical deformation of the soft material. The vehicle swiftly assumes an optimal pose and creates directional flow around itself, which it follows to achieve robust full-space phototaxis. In addition, this phototaxis enables a series of complex underwater locomotions. We demonstrate that this versatility is generated by the synergy of photothermofluidic interactions resulting in closed-loop self-control and fast reconfigurability. The untethered, electronics-free, ambient-powered hydrogel vehicle manoeuvres through obstacles agilely, following illumination cues of moderate intensities, similar to that of natural sunlight.

Revealing the microstructures and seepage characteristics in the uncured rubber-cord composites using micro-computed tomography and lattice Boltzmann approach

The internal microstructure distribution of cord-rubber-air during the processing of uncured rubber-cord composites (URCs) determines the finished product's performance. For the first time, we used computed tomography (CT) and the lattice Boltzmann method (LBM) to establish a geometrical representation model of the real microscopic pore-fracture structures of URCs and investigate the seepage law of fluid in porous URCs, where the reinforced rubber formula was originally designed to reduce CT artifacts of cord. The results showed that the average porosity and pore radius of the original cord (0.2711 and 15.53 μm, respectively) were considerably larger than those of the URCs (0.0509 and 4.46 μm, respectively); the pore number of the cord was the largest when the pore radius was 5–10 μm, accounting for 29.36% of the total number; however, the pore number accounted for 31.36% of the total number of the URCs when the pore radius was 2–3 μm. Moreover, the characteristics of the pore/throat surface area and pore volume/throat length exhibited perfect consistent patterns with those of the pore radius. Furthermore, the fluid flow velocity increased in both cord and URCs as the displacement differential pressure increased, but decreased dramatically as the fluid kinematic viscosity increased. The critical values of displacement differential pressure and kinematic viscosity were different in the cord and URCs samples, presenting 11.1209 Pa/1.3696 × 10−3 m2/s and 14.2984 Pa/2.8869 × 10−4 m2/s, respectively. This phenomenon should be attributed that when the uncured rubber was injected into the original cord sample, its porosity decreased, its pore radius decreased, the number of micro-scale pores increased, and flow resistance became larger, resulting in a higher critical value of displacement differential pressure and a lower critical value of kinematic viscosity.

Mycelium Composite with Hierarchical Porous Structure for Thermal Management.

High-performance porous materials with a low carbon footprint provide sustainable alternatives to petroleum-based lightweight foams and can help meet carbon neutrality goals. However, these materials generally face a trade-off between thermal management capabilities and structural strength. Here, a mycelium composite with a hierarchical porous structure, including both macro- and microscale pores, produced from multiple and advanced mycelial networks (elastic modulus of 1.2GPa) binding loosely distributed sawdust is demonstrated. The morphological, biological, and physicochemical properties of the filamentous mycelium and composites are discussed in terms of how they are influenced by the mycelial system of the fungi and the way they interact with the substrate. The composite shows a porosity of 0.94, a noise reduction coefficient of 0.55 at a frequency range of 250-3000Hz (for a 15mm thick sample), a thermal conductivity of 0.042Wm-1 K-1 , and an energy absorption of 18kJm-3 at 50% strain. It is also hydrophobic, repairable, and recyclable. It is expected that the hierarchical porous structural composite with excellent thermal and mechanical properties can make a significant impact on the future development of highly sustainable alternatives to lightweight plastic foams.

Simulation research on Jamin effect and oil displacement mechanism of CO2 foam under microscale

CO2 foam can solve the problems of serious water invasion in the later stage of water injection development of conventional reservoirs, fracture channeling in unconventional reservoirs and low production rate of medium and low permeability reservoirs caused by reservoir heterogeneity, and the Jamin effect is the key to its role. In order to investigate the influence of injection rate, liquid phase viscosity, surface tension, pore structure on the resistance of CO2 foam through the pore throat and the influence of CO2 foam Jamin effect on enhancing oil recovery, the micro-scale pore throat models were established, and the interface changes were traced by using the level set and phase field methods. The results show that the greater the injection rate or liquid phase viscosity, the greater the pressure and the foam film strength, the greater the Jamin effect resistance; Jamin effect resistance is positively related to surface tension, the greater the surface tension, the greater the driving force required for difficult deformation; Jamin effect resistance is negatively related to radius of pore throat, the greater the radius of pore throat (the smaller the pore-throat ratio), the smaller the Jamin effect resistance; CO2 foam plays an important role in the oil displacement, and it can displace the oil trapped on the wall, and the oil recovery of CO2 foam flooding is 9% higher than that of water flooding. The smaller the oil–water interfacial tension is, the more CO2 foam displacement is. These research results have certain theoretical significance for the effective use of CO2 foam in oilfield development.

Cross-Scale Seepage Characteristics of Fractured Horizontal Wells in Tight Gas Reservoirs.

Tight gas reservoirs are rich in microscale pores and fractures. The effect of microscale gas seepage in tight sandstone matrix on gas well productivity cannot be ignored. At present, the effect of microscale gas flow on the well testing model of fractured horizontal wells has not been systematically studied. In this paper, first, the coupling influence mechanism of "multicomponent gas effect-fracture geometry characteristics" is expounded, second, a seepage model coupling the flow in the fracture and the flow in the gas reservoir is established on the fracture wall surface, and third, an unsteady pressure analysis model for fractured horizontal wells in tight gas reservoirs is established. Results show that (a) when the microscale fracture is at a quite small level, the Knudsen diffusion plays a dominant role at a wide range of pressures; (b) the mass transfer rate of multicomponent shale gas through macrofractures increases with increasing CO2 fraction; (c) the unsteady flow process is divided into six stages in turn: microscale diffusion stage, linear flow stage in fractures, linear flow stage between fractures, early radial flow stage in gas reservoirs, linear flow stage in gas reservoirs, and late radial flow stage in gas reservoirs; and (d) with an increase of dimensionless bottom-hole storage coefficient, the second and third stages of flow are gradually covered up.

Injectable Platelet-Rich Fibrin in Contact with Bone Substitutes, Porous Zirconia, or Laser-Textured Implant Surfaces: A Detailed Morphological Analysis

AbstractThe aim of the present study was to perform a detailed morphological analysis of an injectable platelet rich fibrin after combination with two different particulate hydroxyapatite-based granules, a porous zirconia block, and laser-textured zirconia or titanium surfaces. Blood samples were harvested from three participants to prepare the flowable injectable PRF in contact or not with particulate hydroxyapatite (Hap), bone mineral granules (DBBM), porous zirconia blocks, laser-textured titanium or zirconia surfaces. Optical and scanning electron microscopy (SEM) were used to evaluate the fibrin network density, fibrin fibers’ diameter, blood cells, and the interaction of PRF with the biomaterials. Histomorphometry of the flowable PRF was also performed using the hematoxylin–eosin staining protocol. Specimens were independently evaluated by two blinded and well-trained researchers in histomorphometry and microscopy. Particulate Hap and DBBM shown different morphological aspects by SEM analyses since DBBM revealed macro- and micro-scale pores while Hap revealed a dense structure. Hydroxyapatite and DBBM granules were entirely embedded by the fibrin-network in the presence of leukocytes and blood platelets. The zirconia porous structured was filled with PRF and its components. Also, the laser-structured zirconia or implant surfaces were entirely coated with the PRF fibrin network embedding leukocytes and blood platelets. Laser-textured titanium surfaces revealed macro- and micro-scale irregularities that increase the surface area and retention of the injectable PRF. Histomorphometric analyses revealed complementary details on the distribution of lymphocytes, red blood cells, and fibrin associated with platelet aggregation. The flowing and viscosity of an injectable platelet rich fibrin provided an agglomeration of synthetic or xenogeneic particulate bone substitutes and the coating of porous zirconia and textured implant surfaces as inspected by scanning electron microscopy. A cross-linked 3D-fibrin network was noticed involving the particulate bone substitutes and clogging the spaces into porous blocks as well as at macro-/micro-scale valleys on laser-textured implant surfaces. On the reconstruction of larger bone defects, platelet rich fibrin should be mixed with inorganic bone substitutes and implant surfaces to speed up the early events of the bone ingrowth. In addition, the particulate bioactive ceramics, porous zirconia, and textured implant surfaces provide the mechanical stability of the bone tissues and the 3D-fibrin network for further stimulation of osteogenic cells leading to an enhanced bone healing.

Imbalance of active ions through segmented electrodes: Mass transfer characteristics of vanadium redox flow batteries

The mass transfer that occurs at the interface between the porous electrode and electrolyte is important because it is closely related to the electrochemical performance of batteries. In general, as the materials used for electrodes have irregularly connected microscale pores, various methods exist to predict the permeation path of the electrolyte between the inlet and outlet. In this study, we investigate the use of segmented cells to experimentally visualize the mass transfer properties that occur during electrochemical reactions in porous electrodes. In this work, the measured voltages are quantitatively compared with the voltage deviation for each electrode position for a segment cell that is divided into 25 active areas, each measuring 25 cm2. As a result, the electrochemical reaction for each charge/discharge process caused by the physical and electrochemical properties of the VRFB electrolyte showed a relatively uniform reactivity during the charging process. The strategy of enhancing the supply of active ions by increasing the flow rate does not contribute to reducing the voltage difference inside the active region. When the current density is increased by 100%, the rate of increase of the voltage deviation by the electrode position is 70% and 140% in the charging and discharging process, respectively. Furthermore, in the DoD 100% discharge stage based on the cell voltage, the voltage difference is approximately 6.3 times higher than the average voltage deviation in the SoC 0–100% and DoD 0–90% stages. This paper presents a strategy to ensure stable operation during the system charge/discharge process by measuring the voltage at each position of the porous electrode used as an electrode.

Study on microscale pore structure and bedding fracture characteristics of shale oil reservoir

Accurately characterizing the cross-scale structure of pores and fractures in shale reservoirs is the theoretical basis for efficient exploration and development of shale oil and gas. In this paper, (a) Based on the research background of different shale maturity and sedimentary characteristics, a three-dimensional model of cross-scale pore-fracture structure is established; (b) Based on a large number of CT characterization data of core pore-fracture structure, the characteristics of pore-fracture development under different geometric dimensions (25 mm and 2 mm) are statistically analyzed; (c) Pore and fracture structures of mixed shale, felsic shale and laminated felsic shale is comparatively studied, and the pore structure and bedding fracture characteristics of shale oil reservoir is revealed. Results show that: (a) for the bedding fracture porosity, felsic shale in Group I is 0.36 %–0.89%; mixed shale in Group I is 0.34 %–0.47%; mixed shale in Group III is 0.12 %–0.86%; mixed shale gravelly dolomite in Group III is 0.13 %–0.15%. (b) Compared with block 1, the laminated felsic shale bedding in block 2 is more developed. (c) CT imaging is based on density difference. Different components of shale samples are distinguished by gray scale.

The Micro-Occurrence Mechanisms of Tight Oil: Fluid–Rock Interactions at Microscale Pores, Nanoscale Pores, and Mineral Surfaces

Understanding the micro-occurrence mechanism of tight oil has long been a daunting challenge in the exploration and development of unconventional resources. This article discusses the micro-occurrence mechanism of tight oil through continuous extraction by combining thin casting, fluorescent thin sections, environmental scanning electron microscope observations, physical property testing, and X-ray diffraction experiments. The results indicated that in the tight sandstone of the Chang 8 Formation in the Ordos Basin, the average tight oil content was 35.46% for microscale pores, 35.74% for nanoscale pores, and 28.79% for mineral surfaces. Six types of micro-occurrence states of tight oil were identified: emulsion, cluster, throat, star-like, isolation, and thin film forms. Although clay minerals and heavy components dominate the adsorption of tight oil on mineral surfaces, micro-occurrence is fundamentally an oil–rock interaction process. Hence, oil–rock interactions and occurrence states were combined in this study to identify tight oil’s micro-occurrence mechanism. The van der Waals forces of attraction between asphaltene molecules and a mineral surface play a critical role, and minerals with hydroxyl groups can also combine with carboxyl and hydroxyl groups present in tight oil. As a consequence of the adsorption of heavy components by minerals, tight oil components remain in microscale and nanoscale pores with a higher saturation, increased aromatic hydrocarbon content, and greater fluidity. The heterogeneity of the components due to adsorption influences the physical properties and mineralization framework of tight oil reservoirs. These findings suggest that tight oil occurrence results from the coupling of microscopic occurrence and component heterogeneity in microscale and nanoscale pores.

Highly corrosion-resistant ZIF-8-integrated micro-arc oxidation coating on Mg alloy

The long-term corrosion resistance of conventional micro-arc oxidation (MAO) coatings on magnesium alloy is limited by the inherent micro-scale pores. To address this issue, zeolitic imidazolate framework-8 (ZIF-8) and zinc gluconate (ZnG) loaded ZIF-8 (ZnG@ZIF-8) were synthesized and incorporated into the MAO coating. The electrochemical and immersion tests showed that the MAO composite coating doped with ZIF-8 and ZnG@ZIF-8 ((ZIF-8 + ZnG@ZIF-8)/MAO) displayed optimal corrosion resistance. The corrosion current density (jcorr) of the pristine (ZIF-8 + ZnG@ZIF-8)/MAO composite coating (3.38 nA cm−2) is 63.3 times lower than that of the blank MAO coating (214 nA cm−2), indicating the significant enhancement in corrosion protection of the nanoparticle to the coatings. Even after 32 days of immersion in a 3.5 wt.% NaCl solution, the jcorr of the former was as low as 87.3 nA cm−2, much lower than that of the blank MAO coating (1710 nA cm−2). These findings provide new insights into the design of corrosion-resistant MAO composite on magnesium alloy surfaces via the incorporation of inhibitor-loaded ZIF-8 nanocontainers.

Three-Dimensional Printed Highly Porous and Flexible Conductive Polymer Nanocomposites with Dual-Scale Porosity and Piezoresistive Sensing Functions.

Highly flexible, deformable, and ultralightweight structures are required for advanced sensing applications, such as wearable electronics and soft robotics. This study demonstrates the three-dimensional (3D) printing of highly flexible, ultralightweight, and conductive polymer nanocomposites (CPNCs) with dual-scale porosity and piezoresistive sensing functions. Macroscale pores are established by designing structural printing patterns with adjustable infill densities, while the microscale pores are developed by phase separation of the deposited polymer ink solution. A conductive polydimethylsiloxane solution is prepared by mixing polymer/carbon nanotubes with non-solvent and solvent phases. Silica nanoparticles are utilized to modify the rheological properties of the ink, making direct ink writing (DIW) feasible. 3D geometries with various structural infill densities and polymer concentrations are deposited using DIW. The solvent is evaporated during a stepping heat treatment, leading to non-solvent droplet nucleation and growth. The microscale cellular network is developed by removing the droplets and curing the polymer. Up to 83% tunable porosity is achieved by independently controlling the macro- and microscale porosity. The effect of macroscale/microscale porosity and printing nozzle sizes on the mechanical and piezoresistive behavior of the CPNC structures is explored. The electrical and mechanical tests demonstrate a durable, extremely deformable, and sensitive piezoresistive response without sacrificing mechanical performance. The flexibility and sensitivity of the CPNC structure are enhanced up to 900 and 67% with the development of dual-scale porosity. The application of the developed porous CPNCs as piezoresistive sensors for detecting human motion is also evaluated.

Effect of simultaneous electrical and mechanical stressing on porosity of Ti3C2T x MXene films

MXenes are atomically layered carbides and nitrides of transition metals that have potential for micro-devices applications in energy storage, conversion, and transport. This emerging family of materials is typically studied as nanosheets or ultra-thin films, for which the internal defects are mostly nanoscale flake-flake interface separation type. However, micro-devices applications would require thicker films, which exhibit very high density of microscale pores. Electrical conductivity of thicker MXenes is significantly lower than nanosheets, and the physics of defect size and density control are also different and less understood. Current art is to perform high temperature annealing to improve the electrical conductivity, which can structurally alter or degrade MXene. The key contribution of this study is a room-temperature annealing process that exploits the synergy between electrical pulses and compressive mechanical loading. Experimental results indicate over a 90% increase in electrical conductivity, which reflects a decrease in void size and density. In the absence of compressive loading, the same process resulted in a conductivity increase of approximately 75%. Analytical spectroscopy and microscopy indicated that the proposed multi-stimuli process kept the MXene composition intact while significantly decreasing the void size and density.

Structural, magnetic and magnetocaloric properties of hexagonal MnCoGe-based thin films

The characteristic size of the magnetocaloric materials in magnetic refrigerators, thermomagnetic regenerators and energy harvesters is usually down to micrometer and nanometer length scales, which provides the largest possible contact surface area to the heat transfer liquid. Therefore, it is pivotal to investigate the structural, magnetic and magnetocaloric properties of magnetocaloric materials at micrometer and nanometer length scales. In the present study, we have successfully fabricated MnCoGe-based thin films using the pulsed laser deposition (PLD) technique. The as-deposited film shows a dense surface, homogeneous chemical distribution and a preferred orientation along the c-axis of the hexagonal Ni2In-type structure. In-situ temperature-dependent X-ray diffraction measurements on the as-deposited films reveal an irreversible structural degradation above 300 °C due to the considerable evaporation of the Mn atoms, which causes the formation of microscale pores in the films. The thermomagnetic behavior of the film annealed at 250 °C displays a reversible second-order ferromagnetic transition of the hexagonal phase at Curie temperature TC = 275 K, and a first-order hexagonal-orthorhombic structural transition below 200 K. The decoupling of the magnetic and structural transitions brings reversible magnetocaloric effect with the entropy change ΔS values of 2.5 J/(kgK) and the refrigeration capacity reaching 89 J/kg in Δμ0H = 5 T, which are comparable to other reported magnetocaloric thin films. Moreover, antiferromagnetic coupling in the low-temperature orthorhombic phase was observed, which has rarely been reported in the MnCoGe-based bulk alloys. The different magnetic ground states between the thin film and the bulk alloys may be originated from the strain effect imposed by the Al2O3 substrate. Consequently, this work not only provides insights into the structural, magnetic and magnetocaloric properties of the MnCoGe-based alloys at a nanometer length scale, but also offers a new idea for tailoring the multifunctional properties for this material family.

Permeability of micro-scale structure in coal: Insights from μ-CT image and pore network modelling

For developing coalbed methane resources, it is necessary to quantify the heterogeneity embodied in pore size and spatial distribution, and on the basis of which the correlation between the gas transportability and pore structure could then be clarified in coal. In this study the μ-CT imaging technique was used to examine the micro-scale 3D pore structure in two Qinshui basin coals, and the permeability was estimated based on the reconstructed real pore structure. With CT image processing and 3D pore structure, the pore size, connectivity and the pore spatial distribution were displayed, and the connected pores and isolated pores were distinguished, and the proportion of connected pores of the two studied coals was estimated to be 54.22%–68.52% and 79.48%–91.86%, respectively. The surface porosity of 2D structure slice interprets the local pore connectivity, the minimum surface porosity in certain direction of 3D structure was close to 0 for the studied coals, which means that the pore structure is not connected and it has poor permeability in the direction of coal seam. The gas flow path and flow fluxe in 3D structure was visualized and quantified by gas transport simulation based on real coal pore structure, and the permeability and its anisotropy was evaluated. It indicates that the gas pressure appears to be distributed in a “cluster” shape, and the heterogeneity could be major reason for the low gas transport capacity in coal. The permeability of the two studied coals in the horizontal direction is significantly higher than that in the vertical direction, because the transport channels with low surface porosity in the vertical direction have the tendency to hinder the gas transport.

How to Regulate the Migration Ability of Emulsions in Micro-Scale Pores: Droplet Size or Membrane Strength?

Micro visualization has become an important means of solving colloid and interface scientific problems in enhanced oil recovery. It can establish a relationship between a series of performance evaluations of an oil-water interface under macroscopic dimensions and the actual application effect in confined space, and more truly and reliably reflect the starting and migration behavior of crude oil or emulsion in rock pores. In this article, zwitterionic surfactant alkyl sulfobetaine (ASB) and anionic extended surfactant alkyl polyoxypropylene sulfate (A145) were employed as flooding surfactants. The macroscopic properties of the surfactant solutions, such as the oil-water interfacial tension (IFT), the interfacial dilational rheology and the viscosity of crude oil emulsions, have been measured. At the same time, we link these parameters with the oil displacement effect in several visual glass models and confirm the main factors affecting the migration ability of emulsions in micro-scale pores. The experimental results show that ASB reduces the IFT through mixed adsorption with crude oil fractions. The flat arrangement of the large hydrophilic group of ASB molecules enhances the interactions between the surfactant molecules on the oil-water interface. Compared with sulfate, betaine has higher interfacial membrane strength and emulsion viscosity. A145 has a strong ability to reduce the IFT against crude oil because of the larger size effect of the PO chains at the oil side of the interface. However, the membrane strength of A145 is moderate and the emulsion does not show a viscosity-increasing effect. During the displacement process, the deformation ability of the front emulsions or oil banks is the main controlling factor of the displacement efficiency, which is determined by the membrane strength and emulsion viscosity. The strong interfacial membrane strength and the high emulsion viscosity are not conducive to the migration of droplets in pore throats and may result in low displacement efficiency.

Unraveling the relationship between molecular properties and rapid diffusion in smooth nanopores

Synthetic materials designed to enable rapid and finely tuned diffusion through semi-permeable nano and microscale pores have generally fallen short when compared to their biological counterparts. As a result, applications such as hemodialysis, drug delivery, and biomolecule purifications often require extensive run times and produce imperfect permeate solutions. Towards bridging this gap, we have recently demonstrated that, under a concentration gradient, a wide range of ions diffuse through atomically smooth carbon nanotube pores at rates more than an order of magnitude above those seen in bulk. This observation comes in a pore/molecule size regime where hindered diffusion was previously thought to apply. Here, we extend these results to include more complex and biologically relevant molecules and study how transport rates driven by diffusion depend on molecular properties such as size and flexibility. Further, we work to understand how the unique nanofluidic phenomena occurring in our pores may enable improved performance in dialysis applications by impacting selectivity, permeability, and molecular cutoff profiles. These results help to shed light on mechanisms governing diffusive transport in certain nanoscale pores that remain only partially understood and bring us closer to harnessing them in future separation technologies.

Porous Nickel Electrode for Highly Sensitive Non-Enzyme Electrochemical Glucose Detection

Porous metals have great potential for applications in non-enzyme glucose detection because they have a high surface area and therefore improved the sensitivity of detection and the accuracy of measurement. An LCS/DHBT porous nickel with both macropores (710–1000 μm) and microscale pores (1–25 μm) has been produced by combining the Lost Carbonate Sintering (LCS) and Dynamic Hydrogen Bubble Template (DHBT) processes. Its behavior for glucose measurement has been studied by cyclic voltammetry and compared with a nickel plate and the LCS porous nickel substrate. The as-fabricated porous nickel has an electroactive surface area 18% higher than the LCS porous nickel. The anodic peak current density of the LCS/DHBT electrode in an electrolyte of 0.1 M KOH containing 0.5 mM glucose at scan rates in the range of 25–300 mV/s are in the range of 3.43–13.94 mA/cm2, which is approximately 2 and 10 times those of the plate and LCS electrodes. Increasing the scan rate results in a higher current density and a larger anodic peak potential shift. Current density increases with glucose concentration in several linear segments. The sensitivity and limit of detection of LCS/DHBT nickel electrode in the glucose measurement are 5775 μA/cm2mM and 0.66–2.91 μΜ, respectively. It shows excellent performance for glucose measurement due to its porous nanostructure and its highly effective surface area.

Onsite coalescence behavior of whey protein-stabilized bubbles generated at parallel microscale pores: Role of pore geometry and liquid phase properties

In the formulation of (food) foams, an excess of protein is needed to prevent instant coalescence of bubbles from happening at (sub)millisecond time scales. However, protein adsorption and its influences on coalescence stability rarely have been investigated under such conditions of short time scales and high protein concentrations. In the current study, the coalescence stability of whey protein isolate-stabilized bubbles was studied using a microfluidic device, for a wide range of process conditions, including bubble-forming pore geometries and liquid phase properties. The bubble formation time was varied via the applied pressure, and the corresponding extent of bubble coalescence was quantified via the analysis of bubble sizes obtained through high-speed recordings. The experimental results of bubble coalescence as function of bubble formation time, in the presence of various protein concentrations, were also captured in a semi-empirical model. The amount of proteins accumulating at the surface of coalescing bubbles can be derived from a mass balance, with protein adsorption towards the surface of coalescing bubbles assumed to follow a Langmuir isotherm. The model showed a good fit with the experimental results, and we found that as the protein concentration increases from 2.5 to 7.5% wt., in our device the minimum time required to stabilize bubbles decreases from 0.5 to 0.1 ms. From a practical perspective, our microfluidic device can be used as an efficient tool to capture the instant, (sub)milliseconds, behavior of bubble coalescence, providing closer insights for industrial-scale production of (food) foams that also takes place at these time scales.

Freezing as a Path to Build Micro‐Nanostructured Icephobic Coatings

AbstractSuperhydrophobic photothermal materials with the micro‐nano structure are considered to be promising icephobic surfaces. Unfortunately, converting micro‐nano hierarchical structure concepts into genuine synthetic materials has proven to be exceedingly expensive and difficult, partially because their sophisticated structures need construction at several length scales. Herein, a facile strategy of employing ice crystals to construct sophisticated hierarchical micro‐nanostructured anti‐icing composites with photothermal, self‐healable, and self‐cleaning properties is presented. The composites are covered with interconnected microscale pores replicated from ice crystals, which facilitates the construction of the hydrophobic or superhydrophobic properties based on the Cassie–Baxter model, endowing the coating with self‐cleaning ability. Besides, by adding solar‐to‐heat conversation nanomaterials, the coating can implement in situ solar anti‐/deicing. The abundant micropores caused by ice templates can further improve the photothermal conversion capability through multiple reflections of light. Importantly, the coating is endowed with the self‐healing capability to repair hydrophobicity under sunlight. Additionally, it is demonstrated that the self‐cleaning and self‐healing abilities are mutually reinforcing, synergistically improving anti‐/deicing performances. Overall, the presented ice‐templated coating shows great potential and broad impacts owing to its inexpensive component materials, simplicity, eco‐friendliness, and high energy efficiency.