Cylindrical Channel Research Articles

Facile Fabrication of Monodisperse Vinyl Hybrid Core-Shell Silica Microsphere with Short Range Radial Channel in bi-phase System.

The development of monodisperse hybrid silica microspheres with highly regular pore structure and uniform distribution of functional groups have significant value in the biomolecular separation field. In this work, the short range ordered pore channels are precisely constructed onto the non-porous silica microsphere surface by a bi-phase assembly method, and the cylindrical silica channel introduced a plethora of vinyl groups by "one-pot" co-condensation to form vinyl hybrid silica shell. As hydrophilic interaction chromatography (HILIC) stationary phase, the vinyl hybrid core-shell silica microsphere is simply modified with zwitterion glutathione (SiO2@SiO2-GSH), in which the HILIC enrichment process is significantly shortened due to its specific porous characteristics. Most importantly, SiO2@SiO2-GSH microsphere can enrich 2186 N-glycopeptides from the rat liver protein digest within 2min, which mapped to 806 glycoproteins. Compared with HILIC enrichment result within 1h, the glycoproteins and glycopeptides overlap are 88.3% and 79.1%, performing excellent reproducibility. The short range ordered channels onto the silica microsphere surface exhibit excellent mass transfer efficiency, so the developed bi-phase assembly method is expected to design more advanced hybrid silica materials for other urgently fields.

Numerical simulation of carbonaceous raw material combustion in a coal seam channel

Purpose. The research aims to investigate the combustion behavior of carbonaceous raw materials, specifically pulverized coal, in a cylindrical channel within a coal seam. The research focuses on understanding the temperature field dynamics, the distribution of combustion products, and the stabilization of the combustion process over time. Methods. The research uses advanced Computational Fluid Dynamics (CFD) modeling using non-premixed combustion and the k-epsilon turbulence model. A cylindrical channel with a length of 30 m and a diameter of 1 m is selected, reflecting optimal conditions for co-gasification based on previous studies. Heat transfer processes are incorporated by activating the energy equation, accounting for heat generation from chemical reactions and its transfer via convection, conduction, and radiation. These considerations accurately represent the thermal and flow dynamics in the confined geometry. Findings. The simulation indicates the temperature field stabilization, with a peak of 1540°C achieved in the combustion zone after 24 hours, gradually decreasing to approximately 520°C further downstream. Oxidation reactions are most active within the first 6 m of the channel, producing CO2 as the primary combustion product. The flow velocity analysis indicates intense turbulence near the inlet, enabling efficient mixing of fuel and oxidizer. As the process progresses, turbulence intensity decreases, maintaining a steady distribution of thermal energy and stable downstream flow behavior. Originality. The research has resulted in the development of a comprehensive methodology for modeling pulverized coal combustion process in geometrically constrained coal seam channels, representing the staged progression of the process (early, mid, and final stages). Patterns of temperature field stabilization and the distribution of chemical species along the channel have been identified. Practical implications. TThe findings provide a foundation for optimizing underground coal combustion and co-gasification processes to improve geo-reactor systems’ efficiency.

In silico study of laminar flow through monolith catalysts with different numbers of cylindrical channels

In silico study of laminar flow through monolith catalysts with different numbers of cylindrical channels

Nanochannel geometry-depended behaviors on ion selectivity for salinity gradient energy harvesting

Nanofluidic osmotic energy, which can be directly converted into electricity, is considered a clean and sustainable energy that effectively utilizes salinity gradients. The rational construction of nanochannel is of great significance to ion transport and osmotic energy conversion, but there is currently little attention paid to naturally formed rough and irregular channels. In this study, a model that considers the effects of nanochannel cone angle and waveform surface on interface reaction coupling was established for osmotic energy conversion. The results indicate that cone angle and waveform have a significant effect on osmotic energy conversion. It is found that the reduction of cone angle and the addition of waveform will improve ion selectivity and increase energy conversion efficiency, and ion rectification effect of corrugated cylindrical channel is the most obvious. Meanwhile, enlarging waveform dimensions leads to a significant overlap of electric double layer, resulting in a growth in cation transference number and selectivity, thereby enhancing the system's energy conversion efficiency, which can reach 49.62%. At low concentration ratios, the waveform dimensions are inversely proportional to the maximum output power, whereas at high concentration ratios, increasing the waveform dimensions and applying the waveform at channel entrance can efficiently improve the maximum output power.

Suppression of the Leidenfrost Effect By Controlling the Nanostructure of Aluminum Surfaces

The Leidenfrost effect is a phenomenon in which a liquid droplet forms a thin film of its vapor on a substrate hotter than the boiling point, causing the droplet to float above the hot substrate. The vapor film inhibits heat transfer between the droplet and the substrate, which reduces the cooling efficiency when the droplet cools the high-temperature substrate. It has been known that the Leidenfrost effect can be suppressed by forming nano- and micro-scale pillars and spikes on the substrate surface [1, 2]; however, conventional methods of constructing nano- and micro-structures require expensive equipment and the process is complicated. Anodic porous alumina films with self-ordered cylindrical nanopore channels can be fabricated on aluminum substrate simply by anodizing in appropriate aqueous electrolyte solutions. The structure parameters of porous alumina, such as pore size, interpore distance, and pore length, can be easily controlled by anodizing voltage and time. This study demonstrates that the anodic porous alumina films can be applied to control the Leidenfrost effect.Ultrasonically cleaned and electropolished Al plates (99.999%, 1.0-mm thick) were used as specimens. The specimens were immersed in 0.3 M sodium tetraborate solution (343 K) and anodized at 10-200 V for 60 min. The nanostructure of the anodic porous alumina was observed by SEM. The static contact angle of the specimen was measured with a contact angle meter. The behavior of water droplets on the specimen at 473 K was captured by a high-speed camera. The temperature of the specimen was measured using a thermal imaging camera.Constant voltage anodizing of Al resulted in the formation of porous alumina films with numerous pores. As the anodizing voltage was increased, the pore size increased, with an average pore size of 294 nm at 200 V (Fig. 1a). The static contact angle of the anodized surface became smaller as the pore size increased.Fig. 1b shows snapshots of the behavior of a water droplet (6 μL) on a smooth aluminum surface at 473 K. The water droplet bounced after dropping and took a long time to evaporate due to the Leidenfrost effect. On the other hand, when the same experiment was performed on the surface of an anodized specimen, the water droplets wetted and spread immediately after contact with the substrate and evaporated in about 50 ms while splitting into fine droplets (Fig. 1c). The surface temperature after dropping the water droplet (12 μL) decreased significantly on the porous alumina with large pores. Therefore, the formation of anodic porous alumina film on the substrate surface effectively suppresses the Leidenfrost effect, suggesting that increasing the pore size can improve the substrate cooling efficiency.[1] H. Kim, B. Truong, J. Buongiorno, L. W. Hu, Applied Physics Letters, 98, 083121 (2011).[2] C. Kruse, T. Anderson, C. Wilson, C. Zuhlke, D. Alexander, G. Gogos, S. Ndao, Langmuir, 29, 9798-9806 (2013). Figure 1

Luminescence Changeable CO2-Storage Cylinder: Triple-Stranded Helical Eu(III)/Tb(III) Fluorinated MOFs with Amide Linkers.

Triple-stranded helical lanthanide MOFs with CO2 adsorption properties were investigated. Lanthanide MOFs ([Eu0.1Tb0.9(hfa)3(dpa)]n) are composed of lanthanide luminophores (Eu(III) and/or Tb(III) ions), fluorinated antenna ligands (hfa: hexafluoroacetylacetonate), and polyamide-type linker ligands (dpa: 4-(diphenylphosphoryl)-N-(4-(diphenylphosphoryl)phenyl)benzamide). The cylindrical structure was characterized by single-crystal X-ray analysis, thermogravimetric analysis, and gas adsorption measurements. The inner surfaces of the cylindrical channels were covered with the fluorine atoms of the hfa ligands. The emission intensity ratio (IEu/ITb) in [Eu0.1Tb0.9(hfa)3(dpa)]n is affected by the CO2 gas adsorption behavior. The change in IEu/ITb value was caused by the intermolecular interactions between the CO2 gas molecules and the fluorinated ligands, resulting in an electronic structural change of the lowest triplet excited state in the photosensitized hfa ligands.

Confinement Modulates Axial Patterning in Regenerating Hydra

The establishment of the body plan is a major step in animal morphogenesis. The role of mechanical forces and feedback in patterning the body plan remains unclear. Here we explore this question by studying regenerating Hydra tissues confined in narrow cylindrical channels, which constrain their morphology. We find that frustration between the orientation of the channel and the inherited axis in the regenerating tissues can lead to the formation of a multiaxial body plan. The morphological outcome is directly related to the pattern of nematic topological defects that emerges in the organization of the supracellular actomyosin fibers. When the inherited axis, which can be read out from the initial alignment of the supracellular fibers in the confined spheroid, is parallel to the channel's axis, the tissue regenerates normally into animals with a single body axis aligned with the channel. However, regenerating spheroids that are confined in a frustrated perpendicular configuration often develop excess defects (including negatively charged −1/2 defects) and regenerate into multiaxial morphologies. The influence of mechanical constraints on the regenerated body plan argues against an axial patterning mechanism that is based solely on inherited gradients of biochemical morphogens. We further show that the dependence of the regeneration outcomes on the initial tissue orientation can be recapitulated by a biophysical model, which considers the coupled dynamics of the nematic organization of the actomyosin fibers and a morphogen concentration field, incorporating a mechanochemical feedback loop involving strain-dependent morphogen production at defect sites. Published by the American Physical Society 2024

Comparison of experimental and simulated separation performance in capillary tube-in-manifold devices

A metal tube-in-manifold packed bed capillary column device, designed to overcome common limitations associated with capillary LC separations, is described. Experimental results of initial packing tests with sub-3 μm core-shell particles demonstrated efficiencies greater than 47,000 plates/m for a separation performed using the column device. Computational fluid dynamics (CFD) modeling of the multicomponent separation used for this work was validated against experimental LC results and the optimized model was able to effectively predict component peak retention times. However, the accuracy of predicted efficiencies requires further refinement. The tube-in-manifold design demonstrates that packed capillary columns with cylindrical cross-sectional channel geometry and ultrahigh pressure, low dead volume fluidic connections are achievable.

Tangentially active polymers in cylindrical channels

We present an analytical and computational study characterizing the structural and dynamical properties of an active filament confined in cylindrical channels. We first outline the effects of the interplay between confinement and polar self-propulsion on the conformation of the chains. We observe that the scaling of the polymer size in the channel, quantified by the end-to-end distance, shows different anomalous behaviours under different confinement and activity conditions. In particular, we report scaling exponents that are markedly different from their passive counterparts. Interestingly, we show that the universal relation, describing the ratio between the end-to-end distance of passive polymer chains in cylindrical channels and in bulk is broken by activity. Finally, we show that the long-time diffusion coefficient under confinement can be rationalised by an analytical model, that takes into account the presence of the channel and the elongated nature of the polymer.

Analytical study of frictional interaction of elastic cleaning pig with pipeline wall

Cleaning pigs made of highly elastic materials are used to remove contaminants from industrial gas pipelines. To ensure the movement of the pig in normal operation and narrow sections of the pipeline, it is necessary to generate the required gas pressure in the pig space. The study aims to establish the analytical conditions for the movement of a deformable pig in a cylindrical channel without stopping.A one-dimensional quasi-static model has been developed to analyse the frictional interaction of a moving deformable rod with a cylindrical pipe wall under conditions of uniform radial tightness. The normal contact is assumed to be dense, with no interfacial gas flow along the pig.Based on the solution of the formulated contact problem, the influence of frontal resistance, tension, friction, modulus of elasticity of the material and geometric dimensions of the rod on its stress state and on the value of pressure behind the pig required for the pig to pass through the pipeline without stopping is investigated. It is shown that an increase in the value of each factor leads to an increase in the driving gas pressure in the space behind the pig.In the future, developing the proposed approach for the analytical modelling of pig motion in a pipe with variable narrowing is advisable.Recommendations for the design of deformable pigs for efficient gas pipeline cleaning are given.In analytical form, the dependences of the driving pressure on the key geometric and mechanical parameters of the process were found.

The Poisson–Boltzmann equation in micro- and nanofluidics: A formulary

The Poisson–Boltzmann (PB) equation provides a mean-field theory of electrolyte solutions at interfaces and in confinement, describing how ions reorganize close to charged surfaces to form the so-called electrical double layer (EDL), with numerous applications ranging from colloid science to biology. This formulary focuses on situations of interest for micro- and nanofluidics, and gathers important formulas for the PB description of a Z:Z electrolyte solution inside slit and cylindrical channels. Different approximated solutions (thin EDLs, no co-ion, Debye–Hückel, and homogeneous/parabolic potential limits) and their range of validity are discussed, together with the full solution for the slit channel. Common boundary conditions are presented, the thermodynamics of the EDL is introduced, and an overview of the application of the PB framework to the description of electrokinetic effects is given. Finally, the limits of the PB framework are briefly discussed, and Python scripts to solve the PB equation numerically are provided.

Comparative study of mixing performance in non-Newtonian Xanthan Gum solutions and water using various injection techniques in a cylindrical channel with vortex generators

Comparative study of mixing performance in non-Newtonian Xanthan Gum solutions and water using various injection techniques in a cylindrical channel with vortex generators

Translocation of Gaussian polymers across a nanometric cylindrical channel

We present an analytical model to study translocation of Gaussian polymers across a cylindrical channel of nanometric size with a chemical potential inside the channel. Results show that polymer conformational entropy generates an entropic M-like free energy barrier for translocation. The presence of a small negative chemical potential reduces the entropic free energy barrier rendering the translocation time to follow a power law τ = AN ν as function of polymer size N. Power law exponents ν found here in varying the channel radius R, run from 1.525 to 1.999 for unforced translocation, and from 1.594 to 2.006 for translocation with small chemical potentials when R = 1 nm. Presence of large negative chemical potentials generate a free energy well rendering the translocation time to follow an exponential growth τ = Ae α N . We show existence of a negative chemical potential μ c that minimizes the translocation time due to an interplay of conformational entropy and channel-polymer interactions. The translocation time as function of channel length L grows exponentially as τ = Ae cL , it runs from milliseconds up to decades in the range of lengths found in biological channels. Interestingly, small negative chemical potentials approaching μ c overcome the effect of large channel lengths reducing the translocation time below seconds. Translocation speeds <v(N) > show a maximum of micrometers per second then it decays with polymer size and channel length, the characteristic decay <v(N) > ∼ N −1 has been observed in previous experiments of voltage-driven DNA translocation.

Linear instability of a resting state of the magnetohydrodynamic flows of polymeric fluid in a cylindrical channel (generalized Vinogradov–Pokrovski model)

We study a linear stability of a resting state for flows of incompressible viscoelastic fluid in an infinite cylindrical channel under the influence of an external uniform magnetic field directed parallel to the cylinder axis (we use a generalized rheological Vinogradov–Pokrovski model as mathematical model) in a class of axisymmetric periodic along the axial variable flows. We establish that for some values of the parameters in the case of an absolute conductivity bm=0, the magnetic field can substantially lessen the real part of an exponent for perturbations of the radial velocity component, which is the main element of the instability development. For general case bm≠0, we justify the possibility of removing the instability based on the performed calculations.

A new experimental method to study the flame inhibition performance of low concentration halogenated gas

The minimum fire extinguishing concentration is a key index for the development of next generation chemical clean fire extinguishing gases, which is usually got by the cup-burner. The fire suppression performance of low concentration of chemical gas is hard to be understood by the available methods. In this work, the fundamental acknowledgement of steady flame surface attacking mechanism by halon functional group is newly discussed by conducting a series of bench scale tests with a cylindrical channel under a varied fluorinated gases. The characteristics of flame propagation under differentiated air atmosphere environmental conditions is obtained. The influence of fluorine-containing gas flow rate on flame propagation speed is clarified. A dimensionless relationship including atomic radius, bond length, polarization degree, molar mass and molar volume are proposed to describe the influence of low concentration of fluorine-containing gas on flame propagation speed. It provides an insight for the understanding of the flame inhibition performance of low concentration halogenated gas.

Structure and Dynamics of Carbon Dioxide inside ”Hot” Ice with Cylindrical Channels

Inclusion compound based on crystalline water is increasingly recognized as a promising solution for carbon dioxide (CO2) capture, either for carbon sequestration from greenhouse gas emissions or for gas mixture separation. Molecular dynamics simulations revealed that water crystallizes into a novel porous structure in a carbon nanobrush environment even at room temperature, thus termed ”hot” ice whose structure code is dtc. This study employs a hybrid Grand Canonical/isothermal-isobaric Monte Carlo (GCMC) simulations to investigate CO2 confinement inside the cylindrical channels of ice dtc structure. The results show that CO2 occupancy, here expressed as CO2-to-water mole ratio, is approximately 2:5 at maximum. The simulations also demonstrate the mechanical stability of ice dtc structure under positive pressures when its voids are filled with CO2. Furthermore, molecular dynamics simulations are performed to provide molecular insights into the structures and dynamics of CO2 inside the porous channels framework. The results show that CO2 molecules form a bilayer structure inside the cylindrical channels, where certain molecule orientation angles are favored. Dynamics analysis shows that CO2 molecules are relatively immobile in all directions at maximum occupancy.

Comparative study of two mesoporous magnetic and MCM-41 supported Cu complex: High-performance heterogeneous catalysts for aqueous synthesis of tetrazole

The effects of the carrier were studied in the synthesis of tetrazole. Copper catalysts supported on CoFe2O4 and MCM-41 with serine ligands were prepared. Two mesoporous catalysts, CoFe2O4/Ser/Cu and MCM-41/Ser/Cu, (denote Serine with (Ser)) were synthesized and compared the activity of these catalysts in converting nitrile to tetrazole. The prepared material was characterized using powder X-ray diffraction (XRD),field emission scanning electron microscopy (SEM), energy-dispersive X-ray spectrometer (EDS), elemental mapping, vibrating-sample magnetometer (VSM), and nitrogen adsorption–desorption isotherm. The relation between the textural properties of the catalysts and the catalytic performance was investigated. The X-ray diffraction patterns showed the spinel ferrite type for CoFe2O4/Ser/Cu and amorphous SiO2 for MCM-41/Ser/Cu. The distinctive diffraction peaks in the diffraction curves of CoFe2O4/Ser/Cu, and MCM-41/Ser/Cu were identical to those of CoFe2O4, and MCM-41, confirming the preservation of these phases of supports throughout the functionalization processes and formation of -Ser/Cu moiety on the crystalline CoFe2O4 structure and non-crystalline silica structure. FE-SEM images showed the particles in CoFe2O4/Ser/Cu had an average diameter of 20–50 nm and in MCM-41/Ser/Cu had an average diameter of 50–250 nm. The images showed the uniformity and well-ordering of the particles. The slight aggregation in CoFe2O4/Ser/Cu particles implied that their clustering may be the result of modest attraction forces between them. MCM-41/Ser/Cu sample exhibited a type IV isotherm with an H1-type hysteresis loop and diagrams of the CoFe2O4/Ser/Cu showed a type IV isotherm (type H2 hysteresis loop). The MCM-41/Ser/Cu and CoFe2O4/Ser/Cu showed a mesoporous structure and capillary condensation occurred in the nearly cylindrical and ink bottle channels with non-uniform size or shape. The CoFe2O4/Ser/Cu showed surface area by BET and t-plot of 71.17 m2/g and 64.92 m2/g respectively, mean pore size of 14.06 nm, and pore volume of 0.250 cm3/g. The MCM-41/Ser/Cu showed surface area by BET and t-plot of 639.2 m2/g and 484.6 m2/g respectively, with a mean pore size of 5.44 nm, and pore volume of 0.869 cm3/g. The BJH pore size distribution was between 1 and 10 nm for the MCM-41/Ser/Cu and 1–20 nm for the CoFe2O4/Ser/Cu. Two catalysts were used for the synthesis of tetrazole. The CoFe2O4/Ser/Cu shows better activity in the synthesis of 5–substituted 1H-tetrazoles than the MCM-41/Ser/Cu sample despite its lowest surface area (71.17 m2/g). There is no reduction in the conversion of nitrile to tetrazole after the 6 cycles for CoFe2O4/Ser/Cu and after the 4 cycles for MCM-41/Ser/Cu.

A Semiflexible Polymer Translocation Through a Cylindrical Channel

In this study, translocation of a semi flexible polymer through a cylindrical channel have been investigated. A two-dimensional Monte Carlo simulation was employed, by utilizing the bond fluctuation method (BFM) to investigate the translocation processes of a chain length N. To surmount the entropic barrier, the middle monomers of the polymer have been positioned at the center of the pore, which is situated between the CIS and TRANS regions. Consequently, the static properties of a semi-flexible polymer by calculating the mean square end-to-end distance ‹R2› and the mean square radius of gyration ‹R&amp;lt;sup&amp;gt;g&amp;lt;/sup&amp;gt;2› as functions of the chain length (N) have been examined. The mean square end-to-end distance and the mean square radius of gyration are proportional to the number of monomers N as ‹R2› ~ N1.496 and ‹R2g› ~ N1.505 correspondingly for a short cylindrical channel length L = 2, which aligns with the theoretically predicted. These finding indicates that the relationships between ‹R2› and ‹R&amp;lt;sup&amp;gt;g&amp;lt;/sup&amp;gt;2› and the polymer chain size N are strongly influenced by the channel length L. The dynamic properties by analyzing the translocation time of the polymers also studied. Additionally, the relationship between the escape time τ and the polymer chain length N depends on the pore width W, which is equivalent to the diameter of the cylindrical channel. These research demonstrates that the escape time τ decreases as the width increases and escape time τ increases as the chain stiffness increases.

Molecular Communication Systems in Cylindrical Channels With Non-Newtonian Fluid Flows in IoBNT

Molecular Communication Systems in Cylindrical Channels With Non-Newtonian Fluid Flows in IoBNT

Guest-Induced Helical Superstructure from a Gold Nanocluster-Based Supramolecular Organic Framework Enables Efficient Catalysis.

Mimicking hierarchical assembly in nature to exploit atomically precise artificial systems with complex structures and versatile functions remains a long-standing challenge. Herein, we report two single-crystal supramolecular organic frameworks (MSOF-4 and MSOF-5) based on custom-designed atomically precise gold nanoclusters Au11(4-Mpy)3(PPh3)7, showing distinct and intriguing host-guest adaptation behaviors toward 1-/2-bromopropane (BPR) isomers. MSOF-4 exhibits sev topology and cylindrical channels with 4-mercaptopyridine (4-Mpy) ligands matching well with guest 1-BPR. Due to the confinement effect, solid MSOF-4 undergoes significant structural change upon selective adsorption of 1-BPR vapor over 2-BPR, resulting in strong near-infrared fluorescence. Single-crystal X-ray diffraction reveals that Au11(4-Mpy)3(PPh3)7 in MSOF-4 transforms into Au11Br3(PPh3)7 upon ligand exchange with 1-BPR, resulting in 1-BPR@MSOF-6 single crystals with a rarely reported helical assembly structure. Significantly, the double-helical structure of MSOF-6 facilitates efficient catalysis of the electron transfer (ET) reaction, resulting in a nearly 6 times increase of catalytic rates compared with MSOF-4. In sharp contrast, solid MSOF-5 possesses chb topology and cage-type channels with narrow windows, showing excellent selective physical adsorption toward 1-BPR vapor but a nonfluorescent feature upon guest adsorption. Our results demonstrate a powerful strategy for developing advanced assemblies with high-order complexity and engineering their functions in atomic precision.