Concave Surface Research Articles

Analyze the influence of nozzle shape and orientation on inline arrangement of multiple jets impingement on a concave surface

ABSTRACT The present study reports the thermal behavior of multiple jets on a hot concave surface with different nozzle geometries such as circular and elliptical and different orientation. Tests are performed with five different nozzles at different values of nondimensional nozzle to surface distance (z/d = 2–10) and Reynolds number (5000–28,000). Here, the parameter coefficient of variation (COV) is used to estimate the non-uniformity in the local Nu variation. For N-2, the value of CO V y , non − dim is found to be 50–60% higher compared to N-3 at z/d = 2; while at z/d ≥ 8, for N-3, the value of CO V y , non − dim is found to be 10–15% higher compared to N-2. The higher temperature uniformity ( CO V x , non − dim ) is noted in the fountain region compared to impingement region for the circular and elliptical nozzles. The thermal performance of elliptical jets is found to be sensitive toward the jet orientation at lower z/d values. The magnitude of temperature non-uniformity decreases with the increase in the z/d values. Among the tested nozzles, Nozzle N-2 consistently demonstrates superior performance across all nozzle-to-plate distances and with an increase in the z/d value improvement with nozzle N-2 reduces.

Phosphate-dependent nuclear export via a novel NES class recognized by exportin Msn5.

Gene expression in response to environmental stimuli is dependent on nuclear localization of key signaling components, which can be tightly regulated by phosphorylation. This is exemplified by the phosphate-sensing transcription factor Pho4, which requires phosphorylation for nuclear export by the yeast exportin Msn5. Unlike the traditional hydrophobic nuclear export signal (NES) utilized by the Exportin-1/XPO1 system, cryogenic-electron microscopy structures reveal that Pho4 presents a novel, phosphorylated 35-residue NES that interacts with the concave surface of Msn5 through two Pho4 phospho-serines that align with two Msn5 basic patches, unveiling a previously unknown mechanism of phosphate-specific recognition. Furthermore, the discovery that unliganded Msn5 is autoinhibited explains the positive cooperativity of Pho4/Ran-binding and proposes a mechanism for Pho4's release in the cytoplasm. These findings advance our understanding of the diversity of signals that drive nuclear export and how cargo phosphorylation is crucial in regulating nuclear transport and controlling cellular signaling pathways.

Curcumin-loaded microcapsules with soy and whey protein as wall material: In vitro release, and ex vivo absorption based on the rat small intestine

Plant proteins, serving as an environmentally friendly and cost-effective alternative to animal proteins, have gained widespread usage in encapsulating various bioactive compounds like curcumin. However, understanding how plant protein-based microcapsules compare to those made with animal proteins in terms of disintegration, release, and absorption in the gastrointestinal tract (GIT) remains limited. This study aims to investigate the impact of soy protein isolate (SPI) and whey protein isolate (WPI) as wall materials on the release, stability, and absorption of curcumin. Spray-dried SPI-based microcapsules (SPI–C) exhibited significantly lower encapsulation efficiency (77.1%) and loading efficiency (3.6%) compared to WPI-based microcapsules (WPI–C) (97.6% and 9.6%, respectively). Structural analysis revealed pleated hollow spherical structures for SPI-C and a concave surface with a single-chamber structure for WPI-C. SPI-C demonstrated higher proteolysis (55.8% vs. 44.1%) during in vitro digestion, leading to greater curcumin release ratio (67.9% vs. 59.2%) and digestive stability (97.9% vs. 93.7%) compared to WPI-C. Notably, SPI-C exhibited higher apparent permeability (0.97 × 10−6 cm/s) to the ex vivo rat small intestine than WPI-C (0.44 × 10−6 cm/s). These findings suggest improved gastrointestinal stability and absorption of curcumin encapsulated by SPI, indicating the potential for enhanced utilization of plant-derived proteins in encapsulating bioactive compounds.

Compensation method of the spiral bevel gear tooth surface error based on eight tooth-surface fitting

Abstract The misalignment error between the gear theoretical coordinate system and actual gear coordinate system is illustrated, as well as its influence on the measurement of tooth surface deviation is discussed. On the analysis of the tooth convex and concave surface error measurement process, the measured points in the theoretical coordinate system are transformed from the actual measured points in the actual coordinate system. Then, an eight tooth-surface fitting method is utilized to calculate the misalignment error and the compensation method is given. Finally, actual measurements of three different spiral bevel gears are analyzed, and the misalignment error are calculated. Using the proposed compensation method, both the eccentricity and tilt are compensated to some extent. And the machining suggestions of each spiral bevel gear are also given according to its compensated tooth surface error distribution.

The single RRM domain-containing protein SARP1 is required for establishment of the separation zone in Arabidopsis.

Abscission is the shedding of plant organs in response to developmental and environmental cues. Abscission involves cell separation between two neighboring cell types, residuum cells (RECs) and secession cells (SECs) in the floral abscission zone (AZ) in Arabidopsis thaliana. However, the regulatory mechanisms behind the spatial determination that governs cell separation are largely unknown. The class I KNOTTED-like homeobox (KNOX) transcription factor BREVIPEDICELLUS (BP) negatively regulates AZ cell size and number in Arabidopsis. To identify new players participating in abscission, we performed a genetic screen by activation tagging a weak complementation line of bp-3. We identified the mutant ebp1 (enhancer of BP1) displaying delayed floral organ abscission. The ebp1 mutant showed a concaved surface in SECs and abnormally stacked cells on the top of RECs, in contrast to the precisely separated surface in the wild-type. Molecular and histological analyses revealed that the transcriptional programming during cell differentiation in the AZ is compromised in ebp1. The SECs of ebp1 have acquired REC-like properties, including cuticle formation and superoxide production. We show that SEPARATION AFFECTING RNA-BINDING PROTEIN1 (SARP1) is upregulated in ebp1 and plays a role in the establishment of the cell separation layer during floral organ abscission in Arabidopsis.

Direct ink writing of biomimetic hydroxyapatite scaffolds with tailored concave porosity

Direct ink writing is a promising technology for the fabrication of personalized bone grafts, as it enables the customization of their geometrical conformation with high reproducibility and is compatible with the use of self-setting calcium deficient hydroxyapatite inks. However, the scaffolds obtained by DIW consist mostly of convex filaments, which is a limitation since concave surfaces have been shown to promote bone regeneration in vivo. In this work, we explore the use of triply periodic minimal surface (TPMS) designs in DIW of calcium phosphate self-hardening inks as a strategy to obtain scaffolds with controlled concave macropores. The limitations of the printing parameters with high ceramic loaded inks used in DIW enabled achieving only 20% nominal porosities of Gyroid-, Diamond- and Schwarz-based structures. The inherent layered pores from TPMS geometries allowed obtaining concavities typically unattainable via DIW, bearing substantial implications for subsequent osteoinductive capabilities. Although the mechanical properties were lower in the TPMS-based scaffolds than in the orthogonal patterned ones, the blood permeability of the TPMS-based structures was higher. The concave pore architecture enhanced the osteogenic potential of the biomimetic ceramic, increasing SaOs-2 cell adhesion, proliferation, differentiation and mineralisation.  

Exploring Geometric Chirality in Nanocrystals for Boosting Solar-to-Hydrogen Conversion.

Advancing catalyst design is pivotal for the enhancement of photocatalytic processes in renewable energy conversion. The incorporation of structural chirality into conventional inorganic solar hydrogen nanocatalysts promises a significant transformation in catalysis, a feature absent in this field. Here we unveil the unexplored potential of geometric chirality by creating a chiral composite that integrates geometric chiral Au nanoparticles (NPs) with two-dimensional C3N4 nanosheets, significantly boosting photocatalytic H2 evolution beyond the achiral counterparts. The superior performance is driven by the geometric chirality of Au NPs, which facilitates efficient charge carrier separation through the favorable C3N4-chiral Au NP interface and chiral induced spin polarization, and exploits high-activity facets within the concave surfaces of chiral Au NPs. The resulting synergistic effect leads to a remarkable increase in photocatalytic H2 evolution, with an apparent quantum yield of 44.64% at 400 nm. Furthermore, we explore the selective polarized photo-induced carrier separation behavior, revealing a distinct chiral-dependent photocatalytic HER performance. Our work advances the design and utilization of chiral inorganic nanostructures for superior performance in energy conversion processes.

Numerical Investigation of Thermal Performance for Turbulent Water Flow through Dimpled Pipe

Dimples are tiny indentations on the surfaces of the body that enhance heat transfer and alter fluid flow characteristics on or within the body. Numerical investigations were conducted to analyse the heat transfer and flow characteristics in a cross-combined dimple tube in the range of Reynolds numbers from 6000 to 14000. The finite volume method recognised a novel enhancement model utilising methods for composite-form surfaces. Compared to a smooth tube working similarly, the effects significantly improve the heat transfer index, performance evaluation criteria, and friction factor. A three-dimensional simulation was conducted to clarify the underlying process by which dimples affect thermal performance. The simulation findings suggest that the dimples effectively enhance heat transfer by altering the temperature distribution and increasing the temperature gradient within the central area of the dimple section. A concave surface profile disrupts the flow and prevents the formation of a stable boundary layer, promoting the mixing of hot and cold fluids. Furthermore, the study investigates how geometric characteristics impact thermal and hydraulic efficiencies, emphasising that larger dimples improve overall thermo-hydraulic performance. Specifically, the heat transfer enhancement achieved an average increase of 17.3%, ranging from 18.03% to 38.6%, surpassing that of the traditional smooth tube.

Ethylene electrosynthesis from low-concentrated acetylene via concave-surface enriched reactant and improved mass transfer

Electrocatalytic semihydrogenation of acetylene (C2H2) provides a facile and petroleum-independent strategy for ethylene (C2H4) production. However, the reliance on the preseparation and concentration of raw coal-derived C2H2 hinders its economic potential. Here, a concave surface is predicted to be beneficial for enriching C2H2 and optimizing its mass transfer kinetics, thus leading to a high partial pressure of C2H2 around active sites for the direct conversion of raw coal-derived C2H2. Then, a porous concave carbon-supported Cu nanoparticle (Cu-PCC) electrode is designed to enrich the C2H2 gas around the Cu sites. As a result, the as-prepared electrode enables a 91.7% C2H4 Faradaic efficiency and a 56.31% C2H2 single-pass conversion under a simulated raw coal-derived C2H2 atmosphere (~15%) at a partial current density of 0.42 A cm−2, greatly outperforming its counterpart without concave surface supports. The strengthened intermolecular π conjugation caused by the increased C2H2 coverage is revealed to result in the delocalization of π electrons in C2H2, consequently promoting C2H2 activation, suppressing hydrogen evolution competition and enhancing C2H4 selectivity.

Vertically aligned aerogel with concaved surface topography coupled ordered channel enable efficient solar-driven desalination

Solar-driven desalination has been regarded as a promising energy-saving and sustainable strategy to address the serious freshwater shortage issue. However, its performance is restricted by low solar energy utilization efficiency, water transport, and serious salt deposition. Herein, an efficient solar-driven interfacial evaporator with high solar energy utilization efficiency, fast water transport and robust salt tolerance was developed, via constructing vertically aligned sodium alginate (SA) aerogel with concave surface topography coupled ordered water transport channel structure. Concaved reflecting valley surface was assembled with 3D hierarchical photothermal networks of 2D MXene synergistic 1D carbon nanotube to enhance light absorption capacity. Concaved surface topography with multiple reflective nanostructure (angle 45°, depth 1.5 cm) owns strong sunlight concentration performance, which effectively avoid the light loss and thus enhance the light-absorption over a broad spectrum (0.3–2.5 μm). In another way, hydrophilic SA aerogel with vertically aligned structure, which also provides ordered channels for fast water/vapor transport and high salt rejection ability via strong wicking and diffusion effect. Solar-driven interfacial evaporator with such unique concaved surface topography that coupled ordered valley channels exhibits excellent evaporation rate (2.81kg m−2h−1) and remarkable solar energy utilizing efficiency (98.52 %), while with excellent antibacterial ability during continuously desalination process. Solar-driven interfacial evaporator with unique concaved surface topography coupled ordered valley channels holds great potential in sustainable water purification and desalination.

Arrays of Bowl-Shaped Janus Particle Film with Structured Colors.

Structural colors generated via total internal reflection (TIR) using nanostructure-free micro-concave shapes have garnered increasing attention. However, the application of large micro-concave structures for structural coloration remains limited. Herein, a flexibly tunable structural color film fabricated by casting polydimethylsiloxane (PDMS) on an array of large poly(glycidyl methacrylate) (PGMA) bowl-shaped particles is reported. The resultant film exhibits tunable red to green structural colors with changing observation angles. Moreover, the color can be further tailored by altering the shape of the film itself. The incorporation of the PDMS layer not only facilitates a shift in the locus of TIR from the bottom surface to the top concave surface of the particles, thereby enabling the generation of structural color, but also confers enhanced flexibility to the film. Further decoration with silver nanoparticles imparts antimicrobial properties, yielding a novel antimicrobial coating material with structural colors. The simple and cost-effective strategy for the production of structural color films provides potential applications in antimicrobial coatings, enabling accessible and customizable structural coloration using big-size micro-concave particles.

A new ankylosaurian osteoderm from the Middle Jurassic Oxford Clay Formation, United Kingdom

Ankylosaurs are a characteristic group of dinosaurs recognized by their extensive coverings of dermal bony armour, known as osteoderms, across their bodies. The Oxford Clay Formation (Callovian–Oxfordian, Middle Jurassic) in the UK is important for understanding early ankylosaur evolution as it contains some of the earliest known ankylosaur material, including a cranial osteoderm from the basal-most ankylosaur Sarcolestes (and probable postcranial osteoderms). Here, we describe an isolated osteoderm from the Oxford Clay of Peterborough that exhibits a different morphology to other osteoderms from this formation. The specimen, although incomplete along its transverse axis, measures 52.7 mm by 41 mm. The osteoderm is subrectangular with a concave ventral surface and a low, rounded keel on its dorsal surface that protrudes beyond the posterior margin of the specimen base. This morphology is superficially more similar to the thoracic osteoderms of more derived Cretaceous ankylosaurs from North America (e.g. Borealopelta ), than to Sarcolestes and other Jurassic ankylosaurs (e.g. Dracopelta , Mymoorapelta , Tianchisaurus ), but could represent a currently unknown Sarcolestes morphology. Although its isolated nature prevents reliable identification of the taxon and the body part to which it belonged, the osteoderm nevertheless indicates a larger morphological diversity in the body armour of the earliest ankylosaurs than currently appreciated.

Reynolds number effect of a vortex ring impinging on a concave hemi-cylindrical shell

Experimental investigations were conducted on a single vortex ring impinging on a concave hemi-cylindrical shell with Dm/De = 2 at different Reynolds numbers. Vortex rings with five different Reynolds numbers were generated for experimental studies, i.e., Re = 750, 1500, 3000, 5000, and 7000. The planar laser-induced fluorescence visualizations and two-dimensional particle image velocimetry measurements were used in the experiment. The vorticity field based on the Eulerian framework and the finite-time Lyapunov exponent (FTLE) field based on the Lagrangian framework were used to identify the dynamic processes of vortex rings, respectively. The results show that as the vortex rings impinge on concave surfaces from Re = 750 to Re = 7000, the extension of the main vortex ring in the straight-edged direction is larger than that in the concave direction, and the instability of the vortex ring is promoted. While the Reynolds number is increasing, the vortex ring deformation becomes larger, and the overall vortex ring cross section becomes smaller, leading to a larger attenuation of the vortex ring rotation. Calculations performed by the FTLE field were used to derive the Lagrangian coherent structure to analyze the boundaries of the vortex ring motion process, clearly observe the shape of the secondary vortex connecting segments, and verify the speculation by the vortex ring trajectory identification results. Finally, a dynamic model of vortex rings impinging a concave surface was proposed, and the inference of the experimental process was explained by the model.

3D slope stability analysis considering strength anisotropy by a micro-structure tensor enhanced elasto-plastic finite element method

This article presents a micro-structure tensor enhanced elasto-plastic finite element (FE) method to address strength anisotropy in three-dimensional (3D) soil slope stability analysis. The gravity increase method (GIM) is employed to analyze the stability of 3D anisotropic soil slopes. The accuracy of the proposed method is first verified against the data in the literature. We then simulate the 3D soil slope with a straight slope surface and the convex and concave slope surfaces with a 90° turning corner to study the 3D effect on slope stability and the failure mechanism under anisotropy conditions. Based on our numerical results, the end effect significantly impacts the failure mechanism and safety factor. Anisotropy degree notably affects the safety factor, with higher degrees leading to deeper landslides. For concave slopes, they can be approximated by straight slopes with suitable boundary conditions to assess their stability. Furthermore, a case study of the Saint-Alban test embankment A in Quebec, Canada, is provided to demonstrate the applicability of the proposed FE model.

Heat transfer enhancement on a concave surface using sweeping impinging jets: Comparison of vortex-based and conventional oscillators

While the impinging sweeping jet generated by a conventional fluidic oscillator has been extensively investigated for its remarkable convective heat transfer performance, the cooling performance of the recently designed vortex-based fluidic oscillator on impinged hot plates remains unexplored. This study numerically investigates the cooling performance of oscillatory jets generated by the vortex-based fluidic oscillator compared to the conventional fluidic oscillator and a steady non-oscillatory jet impinging on a hot concave surface. The Fluent 2023R2 software was employed for solving the unsteady Reynolds-averaged Navier–Stokes equations with the k–ω SST model through the finite volume method. Numerical simulations were conducted at various dimensionless nozzle-to-surface distances (X/D = 2, 4, and 6) and Reynolds numbers (20,000, 30,000, and 40,000). The performances of both oscillators were assessed through the time-averaged velocity, temperature, and Nusselt number. The results demonstrated that the vortex-based fluidic oscillator, as an innovative type of fluidic oscillator, outperformed conventional fluidic oscillators by enhancing heat transfer and reducing pressure drop, attributed to its smaller size and higher operational frequency. At X/D values of 2, 4, and 6, the mean Nusselt number for the vortex-based oscillator exhibited respective increases of 19 %, 23 %, and 16 % compared to the conventional oscillator. In addition, these values were respectively 38 %, 34 %, and 24 % higher than those for the steady non-oscillatory jet. Furthermore, the thermal enhancement factor of the vortex-based oscillator demonstrated increases of 20 %, 23 %, and 21 %, respectively, in comparison with the conventional oscillator. These findings suggest that the novel vortex-based fluidic oscillator holds significant promise for replacing conventional oscillators in industrial cooling applications.

Drag increase behavior of micro-textured concave titanium surface generated by oblique laser etching

Titanium alloy has been widely used in the clinical preparation of artificial jawbone implants due to its excellent mechanical properties and biocompatibility. Artificial bone implantation drug-carrying research can realize the targeted release of drugs at the lesion, however, it is still at the technical bottleneck in inhibiting the sudden release of drugs. In this paper, based on the typical wettability model, a drug-loading and release-retarding method for artificial titanium jawbone drug-storage microcapacitor has been proposed by studying the oblique laser etching process of the inner surface of the drug-storage capsule and by investigating the resistance-enhancing mechanism of the texturization of concave surface of the inner wall. Using the oblique laser etching texture, the contact angle measurement reveals that when the laser frequency is 40KHz, the laser pulse width is 11 ns, the scanning speed is 130 mm/s, and the laser incidence angle is kept at 30° and the number of processing is one, the minimum surface contact angle can be obtained is only 8°. By combining the “3 + 2″ nanosecond laser etching device with the laser depth of focus theory, a curved surface laser etching process method was proposed. A titanium alloy jawbone with drug-carrying cavities was printed using SLM 3D printing technology, and the drag-enhancing effect of the texture was verified using sodium fluorescein labeling method, and it was found that the hydrophilic microtexture had a significant drag-enhancing effect on the liquid flow in the microfluidic channel.

Structure-dependent residual stress of thermal barrier coating on turbine blade with exposure to high temperature

This work aims to investigate the structure-dependent residual stress of thermal barrier coating systems (TBCs) on actual turbine blades with curved surfaces, and explore the relationship between stress and failure in different blade regions. A specialized non-destructive stress measurement setup was developed for this purpose. The residual stresses in the top coat (TC) and thermally grown oxide (TGO) layer at different blade regions, namely the convex surface, the concave surface, and the leading-edge surface, were measured during isothermal oxidation services. A phenomenon of residual stress reversal was discovered. The structure-dependent failures of TBCs in different blade regions were found to be strongly correlated with the residual stress in the TGO layer, rather than the TC layer. These results significantly enhance our understanding of the failure mechanism and contribute to the prediction of service lifetimes for turbine blades equipped with TBCs.

1D analytic and numerical analysis of thin film heat transfer gauges and infra-red cameras in non-planar applications

The impulse response method is widely used for heat transfer analysis in turbomachinery applications. Traditionally, the 1D method assumes a: linear time invariant, isotropic, semi-infinite block with planar surfaces and does not accurately model the true geometric behaviour. This paper evaluates the error introduced by the planar assumption and outlines the required modifications for accurate freeform surface analysis. Adapted cylindrical basis functions are defined for the impulse response method and used to evaluate the impact of the 1D planar assumption. The analytic solutions for both convex and concave surfaces are presented. A penta-diagonal algorithm, for a modified numerical Crank-Nicolson scheme, is also evaluated for fast stable implementation of curved geometry simulation. The scheme shows comparable performance to the impulse response, whilst removing the requirement for linear time invariance. The new methods are demonstrated in the case of aerothermal analysis for heat transfer in a turbine nozzle guide vane. A 3D ANSYS simulation is used as a benchmark and further highlights the importance of the curvature effects. The methods are extended using curvature mapping for infra-red camera data, enabling direct 3D thermal simulation or the fast calculation of freeform curvature. This paper defines the methodology to analyse heat transfer measurements on non-planar geometry.

Effect of the Ni/CeO2 mesoporous structure on the proper balance of active sites present for CO2 methanation: An in-situ NAP-XPS study

The dependence of the mesoporous structure (mp) on the catalytic performance of Ni/CeO2-mp and Ni/CeO2-La2O3-mp was evaluated for high-quality mesoporous materials prepared from an SBA-15 template. The samples were characterized by different analytical techniques followed by the catalytic evaluation in a fixed bed reactor (GHSV 36,000 h−1). From these results, ceria-mesoporous samples (CeO2-mp) showed a highly ordered pore system with assemblies of slit-shaped mesopores, and a moderate improvement in CO2 conversion to CH4 due to the presence of basic sites for the Ni/CeO2-La2O3-mp. Subsequently, the influence of the mp-structure on their reactivity was investigated by evaluating the Ni0 and Ni2+-CeO2 active sites for CO2 methanation from in-situ NAP-XPS experiments as a function of both chemical environment (CO2 / H2) and operating temperature (up to 350 °C). The results highlighted the critical role of mesopores in maintaining the proper balance of the active species (Ni0/Ni2+-CeO2 ∼ 2.5) that are present on the catalyst surface, leading to enhanced reactivity over a wide range of operating temperatures (250–350 °C) compared to conventional ceria supports. Furthermore, it has been demonstrated that this spectroscopic technique provides valuable insights into the concave surface behavior for monitoring reactivity on mesoporous catalysts, allowing us to contribute to the advancement of methanation reaction technology using CO2.

Mixing Performance of a Passive Micromixer Based on Split-to-Circulate (STC) Flow Characteristics.

We propose a novel passive micromixer leveraging STC (split-to-circulate) flow characteristics and analyze its mixing performance comprehensively. Three distinct designs incorporating submerged circular walls were explored to achieve STC flow characteristics, facilitating flow along a convex surface and flow impingement on a concave surface. Across a broad Reynolds number range (0.1 to 80), the present micromixer substantially enhances mixing, with a degree of mixing (DOM) consistently exceeding 0.84. Particularly, the mixing enhancement is prominent within the low and intermediate range of Reynolds numbers (0.1<Re<20). This enhancement stems from key flow characteristics of STC: the formation of saddle points around convex walls and flow impingement on concave walls. Compared to other passive micromixers, the DOM of the present micromixer stands out as notably high over a broad range of Reynolds numbers (0.1≤Re≤80).