Pore Generation Research Articles

Sub-millisecond keyhole pore detection in laser powder bed fusion using sound and light sensors and machine learning

Abstract Laser powder bed fusion is a mainstream additive manufacturing technology widely used to manufacture complex parts in prominent sectors, including aerospace, biomedical, and automotive industries. However, during the printing process, the presence of an unstable vapor depression can lead to a type of defect called keyhole porosity, which is detrimental to the part quality. In this study, we developed an effective approach to locally detect the generation of keyhole pores during the printing process by leveraging machine learning and a suite of optical and acoustic sensors. Simultaneous synchrotron x-ray imaging allows the direct visualization of pore generation events inside the sample, offering high-fidelity ground truth. A neural network model adopting SqueezeNet architecture using single-sensor data was developed to evaluate the fidelity of each sensor for capturing keyhole pore generation events. Our comparative study shows that the near infrared images gave the highest prediction accuracy, followed by 100kHz and 20kHz microphones, and the photodiode sensitive to processing laser wavelength had the lowest accuracy. Using a single sensor, over 90% prediction accuracy can be achieved with a temporal resolution as short as 0.1 ms. A data fusion scheme was also developed with features extracted using SqueezeNet neural network architecture and classification using different machine learning algorithms. Our work demonstrates the correlation between the characteristic optical and acoustic emissions and the keyhole oscillation behavior, and thereby provides strong physics support for the machine learning approach.

An efficient ultrasound vibration strategy for suppressing intra-bundle pores and regulating pore morphology in carbon fiber-reinforced composites

The competitive resin flow between intra- and inter-bundles, always causes the generation of intra-bundle pores during resin transfer molding (RTM), thereby weakening composite mechanical performance. Accordingly, an ultrasound vibration strategy is originally developed to efficiently suppress and improve the spatial morphology and distribution of intra-bundle pores in RTM manufacturing. The effects of ultrasound vibration on the spatial evolution of intra-bundle pores are systematically investigated, furthermore, the suppression mechanisms of intra-bundle pores are revealed. Additionally, an empirical model that predicts porosity under ultrasound vibration, is established and well validated for the developed ultrasound vibration strategy, which provides a feasible path for effectively manufacturing composites. X-ray micro-computed tomography experiments verify that applying a short period of ultrasound vibration balances the dual-scale flow by regulating the modified capillary number, thereby significantly reducing porosity by up to 59.4 %. Numerical analyses indicate that the acoustic cavitation and acoustic flow induced by the ultrasound vibration, facilitate the collapse and transverse migration of larger bubbles, thereby remarkably suppressing the connected pores and larger pores. In particular, the ultrasound vibration strategy completely removes the pores larger than 300 μm. Besides, the collective effects of vibration, compression, and shear forces contribute to forming near-circular pores, which are beneficial for ensuring the expected mechanical performance of composites.

Novel thermal-regulation and temperature-responsive controlled-release fibermats with porous sheath-core structures

Active regulation of the wound microenvironment as well as on-demand drug delivery have proven to be effective ways to accelerate wound healing, and the development of advanced textiles offers feasibility. A novel fibermat with thermal-regulation and temperature-responsive controlled-release properties was fabricated by using coaxial electrospinning, consisting of porous sheath-core polylactic acid (PLA)/ polyethylene glycol (PEG) fibers. The pore generation in the PLA shell of the PLA/PEG fiber was achieved through a phase separation method. The fiber diameter and pore size of the obtained fiber could be controlled by adjusting the flow rate of shell solution during electrospinning. Increasing the flow rate of shell solution form 0.8 mm·min-1 to 1.4 mm·min-1 resulted in an increase in fiber diameter from 4.8 μm to 15.3 μm, and an increase in pore size from 59.4 nm to 305.6 nm. Due to the high enthalpy and coverage of the PEG core, the PLA/PEG fibermats exhibited excellent thermal-regulation performance, with a surface temperature that was 2.5 °C- 5.6 °C lower than that of pure PLA fibermat during heating process. On-demand release was achieved by directly controlling the core layer of the coaxial PLA/PEG fiber through temperature. The hydrophobicity of the PLA shell initially reduced burst release, followed by increased release as the temperature reached the phase transition temperature of PEG. Furthermore, this advanced fibermat demonstrated desirable moisture permeability, appropriate mechanical properties and good thermal stability, indicating broad potential applications in medical and health fields.

In situ generation of (sub) nanometer pores in MoS2 membranes for ion-selective transport

Ion selective membranes are fundamental components of biological, energy, and computing systems. The fabrication of solid-state ultrathin membranes that can separate ions of similar size and the same charge with both high selectivity and permeance remains a challenge, however. Here, we present a method, utilizing the application of a remote electric field, to fabricate a high-density of (sub)nm pores in situ. This method takes advantage of the grain boundaries in few-layer polycrystalline MoS2 to enable the synthesis of nanoporous membranes with average pore size tunable from <1 to ~4 nm in diameter (with in situ pore expansion resolution of ~0.2 nm2 s−1). These membranes demonstrate selective transport of monovalent ions (K+, Na+ and Li+) as well as divalent ions (Mg2+ and Ca2+), outperforming existing two-dimensional material nanoporous membranes that display similar total permeance. We investigate the mechanism of selectivity using molecular dynamics simulations and unveil that the interactions between cations and the sluggish water confined to the pore, as well as cation-anion interactions, result in the different transport behaviors observed between ions.

Interaction between POM and pore structure during straw decomposition in two soils with contrasting texture

Particulate organic matter (POM) decomposition is influenced by soil pore structure, and the volume loss associated with POM decomposition might also promote the generation of new pores. However, the interaction between POM decomposition and soil pore structure remains unclear. Therefore, the objective of this study was to explore this interaction during straw decomposition. A 57-day soil incubation experiment was conducted using 13C-labelled maize straw in both Shajiang black soil and Fluvo-aquic soil, with two bulk densities (1.2 g/cm3, T1.2 and 1.5 g/cm3, T1.5). The loss of POM volume and the changes in soil pore structure, both before and after the incubation experiment, were quantified using X-ray micro-computed tomography (μCT). The results showed that there was a significantly greater volume loss of POM in Shajiang black soil (POM volume loss: 58.2–75.0 %) compared to Fluvo-aquic soil (34.0 %). Within the Shajiang black soil, decomposition of POM and the release of respired 13CO2 were notably higher in the soil from the T1.2 treatment compared to the T1.5 treatment (P<0.05), while no significant difference was observed in Fluvo-aquic soil. Image-based porosity and mean pore distance emerged as primary determinants of POM variations in Shajiang black soil. Furthermore, our results underscore the positive role of pores ranging from 50 to 300 μm in diameter (Ø) in facilitating rapid POM decomposition, as evidenced by a higher 13CO2 release. In Shajiang black soil, POM decomposition increased the porosity of 100–200 μm, 200–300 μm, and >300 μm Ø pores by 26.2 %, 51.8 % and 82.9 %, respectively, in the T1.2 treatment (P<0.05), and 50–100 μm Ø pores by 24.7 % in the T1.5 treatment (P<0.05). Our findings emphasize the significance of 100–300 μm Ø pores in gas transport and fresh POM decomposition, highlighting the pivotal role of POM decomposition in shaping soil pore structure.

Uncovering the membrane and pore formation mechanisms of the lysozyme membrane made via the amyloid-like assembly

Biomimetic protein membranes have attracted increasing interests because of their distinctive separation properties in the membrane field. Low-cost and stable protein lysozyme has been intensively invetigated to fabricate high-performance sepration membranes via a facile and scalable method of amyloid-like assembly. However, the pore formation mechnism of the lysozyme membrane remains unclear. Herein, the lysozyme membranes were fabricated and the membrane formation mechnism and separation properties were investigated experimentally. Molecular dynamics simulation (MDS) was also employed to reveal the pore formation mechanism of the lysozyme membrane. The fabricated lysozyme membrane achieved a stable high water permeance of 10.2 L m−2 h−1 bar−1, as well as a relatively high separation factor (9.5) towards antibiotic and sodium chloride. MDS results found that the membrane pore size is governed by the amino acid compositions and is negatively dependent on the intermolecular forces among amino acids around the pores. Selective pores with 0.54 nm in diameter are primarily formed by these amino acids including alanine (35 %), aspartic acid (25 %), arginine (15 %), phenylalanine (11 %), and lysine (7 %), in which half of them have hydrophobic side chains with no charge, and another half have hydrophilic side chains with balanced charges. This work may stimulate the development of highly permeable and selective protein membranes by carefully engineering their amino acid compositions with optimal charges and hydrophobicity for generation of numerous selective pores.

Syngenetic effects in co-activation of willow wood with homogenous biochar facilitate pore generation in activation

Mixing feedstocks of varied aromatic/aliphatic content is a simple method for tailoring pore structures of activated carbon (AC) in activation. Herein, willow wood and homogenous biochar produced at 300 or 500°C, which have distinct content of aliphatic component, were co-activated with K2C2O4, at 800°C for changing pore characteristics of resulting AC. The results indicated that co-activation of willow and biochar diminished production of AC and impacted evolution of organics and gases through intensive volatiles-char interactions. The AC from the co-activation of willow with either biochar-300 or biochar-500 exhibited higher specific surface area than that from direct activation of willow (1409.7 or 1297.0 m2 g−1 versus 1243.6 m2 g−1), which was also higher than calculated average of that from feedstock (ca. 1160 m2 g−1). This resulted from intensified gasification of the biochar with H2O/CO2 derived from willow, creating additional macropores and micropores of enlarged pore sizes. The enhanced gasification also reduced crystallinity of graphitic carbon, lowered O content via accelerated deoxygenation and diminished CO on nascent AC. Volatiles-char interactions also minimized pore filling from carbonaceous deposit generated from secondary condensation of primary volatiles. Additionally, direct activation of aliphatic-rich willow tended to form more micropores, while more mesopores were formed from aromatic-rich biochar.

Assembly of 3D printed N-doped biochar as impeller with CaCO3 as sacrificial pore generator for enhanced dye adsorption

Three-dimensional (3D) printed monolithic catalysts/adsorbents have attracted much attention due to their excellent properties. Herein, the rice husk-derived nitrogen-doped biochar (using urea as the nitrogen dopant) was printed into monolithic adsorbents using direct ink writing technology, and then assembled as agitating paddles for organic dye adsorption. To reduce the over-embedding of active sites in the polymeric matrix, CaCO3 particles in nano-sized or micron-sized were added as sacrificial pore generators to form macropores and expose active sites, leading to an enhanced mass transfer efficiency. Material characterization results confirm the self-sacrificial role of CaCO3. The 3D-printed adsorbents with micron-sized CaCO3 (denoted as 3D-HRSCCm) possessed excellent adsorption performance, as evidenced by a high adsorption capacity and kinetics study. Meanwhile, 3D-HRSCCm adsorbents were mounted as agitating impellers which demonstrated excellent reusability with the adsorption efficiency remaining above 90% after ten cycles. Furthermore, the 3D-HRSCCm exhibited excellent adsorption properties for various dyes such as methylene blue, rhodamine B, crystal violet, and malachite green. Moreover, the numerical simulation confirms that the introduction of CaCO3 as a pore generator improved diffusion by providing wider channels and facilitated the mass transfer that accelerated the adsorption rates.

Hierarchically porous structure based on humic acid endogenous modified carbon electrodes for microbial electrochemical system energy recovery and electroactive biofilm conditioning

The microbial electrochemical system (MES) holds promise for in synchronously wastewater treatment and resource utilization, yet it is hampered by suboptimal electron transfer efficiency between the electrode and exoelectrogen. Generating highly active biofilms and facilitating efficient electron exchange at the anode-bacteria interface are critical for MES enhancement. Customization of electrode components and structure can be achieved through endogenous modification of the carbonizing precursor. Herein, we introduced oxygen-containing groups and heteroatoms into the carbon skeleton by doping with humic acid during the fabrication of phenolic-based carbon electrodes. This process was further refined by combining endogenous humic acid doping with controlled pore generation techniques using an anionic active agent and sacrificial templates, establishing a dual-channel optimization strategy for component and structural regulation. Consequently, the resulting sodium humic acid-modified porous electrodes (SHEs) exhibited superior wettability (48 ± 1.5°) and enhanced redox activity owing to their rich oxygenic functional groups. The hierarchical porous architecture and roughened surface texture of the SHEs contributed to their notable capacitance (1280 mF) and biocompatibility. Specifically, the SHEPS samples achieved the highest energy density of 4200 ± 48 mW m−2 and fostered a biofilm with Geobacter content of 78%. The synergistic interaction between exoelectrogens and non-exoelectrogens bolstered the electrochemical performance and stability of the biofilm. This study introduces a novel approach for the synchronous regulation of endogenous components and structure, guiding the design of high-performance, free-standing 3D electrodes for MES applications. These electrodes promote the development of highly electrochemically active biofilms and efficient energy capture, propelling MES towards practical implementation.

Confined graphitization induced pore generation for designing novel potassium-ion battery carbon anode with large capacity and ultra-long cycle life

Carbon is one of the most superior anode materials for K-ion batteries but faces the challenges of low capacity and poor cycle stability. In general, the K+ storage capacity depends on the graphitized carbon layers and defective structure, while the cycle stability can be enhanced by constructing sufficient nanospace to alleviate the volume expansion during the potassiation/depotassiation process. However, the above structures are difficult to integrate into a single carbon material because graphitization often eliminates defects and pore structures. In this work, we find that ultrathin carbon sheets have a confined graphitization effect, which allows the carbon layer to orientationally arrange at a low heating-treatment temperature. More importantly, this orientational arrangement causes size shrinkage, inducing structural splitting on the faces of the carbon sheets and producing abundant defects and a large number of pores. Based on this, we obtain a novel carbon with highly graphitized, large-surface-area and defect-rich frameworks, which gives a K+ storage capacity of 358 mAh g−1, and after 4000 cycles, this carbon shows no obvious capacity degradation, with a capacity retention rate of nearly 100 %. Carbon anodes of K-ion batteries with such large capacity and long cycling life have rarely been achieved before.

Effect of Y2O3 on high temperature thermal compression performance of Cu–10W composites and microstructure analysis

In this study, Cu–10W and 2 wt%Y2O3/Cu–10W composites were successfully prepared via mechanical ball milling and spark plasma sintering. Hot compression experiments on the two materials were carried out in the temperature range of 300°C-600 °C and in the strain rate range of 0.01 s−1–10 s−1. The hot deformation activation energy of the two materials was calculated and a constitutive equation was established. The optimum hot deformation process parameters were obtained according to a hot processing map. The effects of Y2O3 on the thermal deformation behavior of the Cu–10W composites and their microstructures were investigated, and the results showed that Y2O3 could enhance the stability of Cu–10W at high temperatures. The activation energies of thermal deformation of Cu–10W and 2 wt%Y2O3/Cu–10W were 159.56 kJ/mol and 129.85 kJ/mol, respectively. Moreover, Y2O3 improved the interfacial bonding strength of Cu and W in the Cu–10W material, effectively preventing the generation of microcracks and pores during the high-temperature compression process; Y2O3 provides more nucleation sites in the recrystallization process, which is favorable for the excitation of recrystallization. A low strain rate at high temperatures favors the occurrence of recrystallization, and the 2 wt%Y2O3/Cu–10W composites tend to exhibit discontinuous dynamic recrystallization (DDRX) under high-Z-value conditions and continuous dynamic recrystallization (CDRX) under low-Z-value conditions.

Microstructure and flame-retardant properties of the TF550 titanium alloy by ultrasonic vibration assisted laser solid forming

More and more attention has been paid to the application of flame retardancy and surface strengthening of titanium alloys in the aerospace field. In this paper, ultrasonic vibration assisted the laser solid formed (LSFed) TF550 flame-retardant titanium alloy was studied, and the influence of ultrasonic vibration on the microstructure and flame-retardant properties of the LSFed TF550 alloy was analyzed. The results showed that the LSFed TF550 alloy after ultrasonic vibration treatment effectively reduced the generation of pores. When the ultrasonic amplitude was 60 μm, the porosity was the lowest. The porosity of the sample was reduced from 3.84 % to 0.53 %, with the reduction of 86 %. The ultrasonic vibration results in the CET transformation of LSFed TF550 alloy specimen, and the average grain length-width ratio decreases from 5.3 to 1.2, and the microstructure of the specimen changes from the average width of 214 μm to the average grain size of 144±12 μm. Especially when the ultrasonic amplitude is 90 μm, the equiaxial grain size and the grain length-width ratio are the lowest. The effect of ultrasonic vibration at different positions was different. The higher the deposition height, the more columnar crystals in the microstructure and the less equiaxed crystals. When the deposition height was 43 mm, equiaxed crystals and columnar crystals began to coexist. Due to the grain refinement effect of ultrasonic vibration, the number of grain boundaries was increased, and the flame-retardant properties of the LSFed TF550 alloy was improved.

Local parallel free generation and dynamic affine transformation method for soil three-dimensional pore structure information model

The soil three-dimensional (3D) pore structure information model has become a new hotspot in the research of cross-scale disposal of information such as ecology, engineering, and geology. It can solve problems such as the intelligent evaluation of ecological water–soil–air–plant feedback, intelligent risk control of foundation compression deformation, and multiscale intelligent disaster prediction and prevention. However, the current soil 3D pore structure model primarily draws on the global one-time static generation in simulation software, leading to low reliability, low stability of multiple generations, poor variability, difficulty in real-time transformation, high consumption of computing resources, and long generation time, making it challenging to meet the requirements of the rapid processing of information models. Therefore, this study adopts the 3D Drawing Protocol (WebGL) technology and implements the scaling, rotation, and translation transformation of 3D pore structures based on the principle of dynamic affine transformation. The random generation and distribution of pores are realized using the improved Monte Carlo method, and the loading response efficiency of the system is optimized. The dynamic interactive operation of arbitrary increasing and decreasing of pore model is realized using the ray and plane intersection detection principle. Finally, this information system established a visual correlation between the content and reaction time of water-retaining agents and soil porosity and pore distribution through tests on the impact of water-retaining agents on soil pore changes. The information system achieved the real-time tracking of soil pore changes under the action of water-retaining agents. This research solves the problems of static and low generation efficiency of the soil mesopore structure in traditional models and realizes the real-time characterization and visualization of dynamic changes and the distribution of the soil pore structure under the influence of external conditions, which can provide an intuitive visualization platform for mesogeological structure research.

Dynamics of pore formation and evolution during multi-layer directed energy deposition additive manufacturing via in-situ synchrotron X-ray imaging: A case study on high-entropy Cantor alloy

Blown-powder directed energy deposition (DED) additive manufacturing is impeded for novel alloys processing by perceivable and detrimental porosity. During multi-layer depositions, however, mechanisms of pore formation and evolution remain elusive for developing pore mitigation strategies. Here, conduction-mode multi-layer DED process of an exemplary high-entropy Cantor alloy have been investigated in-situ by high-energy high-speed synchrotron X-ray imaging. Three new pore formation mechanisms are unveiled when depositing first layer and successive layers: gas pore induced by high-velocity powder injection into melt pool, pore generated from swirl shear of turbulent melt flow, and pore trapped by surface wave. Three pore formation mechanisms are reconfirmed: pore inheritance from feedstock powder, pore generation when laser remelting defect-sensitive locations of existing pore from previous layer or unmelted powder attached on the melt pool surface, and pore formation as cooling of melt pool. A unique mechanism for pore elimination is proposed: a counter-Marangoni melt flow is experimentally found in the stable melt pool and contributes to the prolonged pore lifetime at tens of milliseconds scale; pores are prone to coalesce into larger sizes in laser interaction zone and the adjacent location with circulation zone; coalesced larger pores driven by combined effect of Marangoni and buoyant forces easily get eliminated from melt pool. The results of pore formation and evolution dynamics revealed in Cantor alloy provide quantified experimental data for high-fidelity computational modeling and in-depth insights of porosity control for high-entropy alloy printing down to melt pool scale.

Effects of Carbon Spacer Length on Conformational Transitions and Protein Adsorption of Polyzwitterions.

The properties of polyzwitterions are closely linked to their carbon spacer length (CSL) between oppositely charged groups. A thorough understanding of the effect of CSL on the properties of polyzwitterion-functionalized membranes is important for their fouling resistance and separation performances. In this work, polyzwitterion-functionalized membranes with different CSLs are prepared by coupling selective swelling-induced pore generation with zwitterionization, and the investigation is focused on comprehending the molecular mechanisms underlying protein resistance and conformational transitions within polyzwitterions under varying CSLs. The zwitterionized films show an enhancement in the surface negative potential with the increase of CSL, attributed to the negatively charged groups distanced from the positively charged groups. Quartz crystal microbalance with dissipation (QCM-D) demonstrates that zwitterionized films with different CSLs display distinct levels of resistance to protein adsorption. The trimethylamine N-oxide-derived polymer (PTMAO, CSL = 0) zwitterionized film shows the highest resistance compared to the poly(3-[dimethyl(2'-methacryloyloxyethyl] ammonio) ethanesulfonate (PMAES, CSL = 2) zwitterionized film and the poly(sulfobetaine methacrylate) (PSBMA, CSL = 3) zwitterionized film, owing to its electrical neutrality and pronounced hydrophilicity. Moreover, analysis of the anti-polyelectrolyte behaviors reveals that PTMAO does not undergo a significant conformation transition in deionized water and salt solutions, while the conformations of PMAES and PSBMA display to be more salt-dependent as the CSL increases, attributed to their increased polarization and dipole moment. As a result, the permeability of zwitterionized membranes exhibits enhanced salt responsiveness with the increase in CSL. The findings of this study are expected to facilitate the design of adsorption-resistant surfaces desired in diverse fields.

Reignition characteristics of lignite affected by pre-oxidation and liquid nitrogen cold soaking

The propensity of residual oxidized coal to be reignited within enclosed fire areas in coal mines under liquid nitrogen (LN2) cold soaking remains unclear. Therefore, scanning electron microscopy (SEM), low-temperature nitrogen adsorption (LTNA), and thermogravimetric (TG) experiments were conducted to characterize the pore structure and secondary oxidation of oxidized cold-soaked coal. The results indicate that pre-oxidation or cold soaking alone can promote the generation and merging of pores and make the pore structure more complex, especially when pre-oxidized. However, pore evolution is suppressed and then improves when lignite is simultaneously subjected to pre-oxidation and cold soaking. In particular, the macropore volume and specific surface area decrease and then increase. The cryogenic shrinking of the LN2 results in the collapse of the loose coal matrix, which subsequently blocks the macropores. In contrast, vaporization expansion enhances pore connectivity with continuous LN2 injections, transforming mesopores into macropores, especially in the pore ranges of 2–5 nm and >50 nm. Additionally, pre-oxidation or cold soaking alone improves the oxidizing activity and combustion performance of raw coal. However, continuous cold soaking initially increases and subsequently decreases the characteristic temperatures and activation energy of oxidized coal. Oxidization at 200 °C with one cold soaking can further lower reignition propensity. The average activation energy of oxidized coal decreases by 22.9%–29 % when soaked more than three times. The improvement in combustion property is closely related to the increasing number of macropores because a larger pore volume and specific surface area are conducive to oxygen diffusion and adsorption. Therefore, pre-oxidation and cold soaking promote and inhibit the reignition of coal when performed simultaneously. These results provide theoretical guidance for rational liquid-nitrogen injection to control coal fires.

Synergistic effect of pore generation and nitrogen doping on the enhanced CO2 capture and selectivity of carbon nanofibers

The porosity and heteroatom doping of carbon materials are crucial for their adsorption capacity and selectivity toward CO2. Herein, nitrogen-doped microporous carbon nanofibers (CNFs) were prepared by carbonizing electrospun polyacrylonitrile (PAN) nanofibers, using nitrogen-rich polyvinylpyrrolidone (PVP) as porogen and nitrogen source simultaneously. The synergistic effect of pore generation and nitrogen doping improved the porosity and preserved a substantial nitrogen content in the CNFs. Compared to the nitrogen-free polyethylene glycol (PEG) porogen, the incorporation of PVP can facilitate nitrogen doping during the carbonization process. With an increasing amount of PVP addition, the specific surface area of the CNFs significantly expanded to 410 m2/g, maintaining a high nitrogen content of 10.32 wt%. The porosity and nitrogen functionalities (Pyridinic N and pyrrolic N) collaborated synergistically in determining CO2 adsorption capacity, with elevated nitrogen content resulted in improved selectivity. The CNFs exhibited remarkable IAST CO2/N2 (10:90) selectivity of 38 and cycling stability, demonstrating their potential for long-term practical applications. This work provides unique inspiration for the design of porous nanofibers with exceptional CO2 adsorption capacity and selectivity.

Effect of Nano-TiO2 and Polypropylene Fiber on Mechanical Properties and Durability of Recycled Aggregate Concrete

In order to promote the engineering application of recycled concrete, the effects of PPF and nano-TiO2 dioxide on the mechanical properties and durability of recycled concrete were studied.Polypropylene fiber recycled concrete(PRAC) and nano-TiO2 recycled concrete(TRAC) were prepared by adding different volume contents of PPF and nano-TiO2. The experimental findings demonstrated that the PPF and nano-TiO2 improved the splitting tensile strength of RAC better than the compressive strength. When the volume content of nano-TiO2. and PPF is 0.8% and 1.0%, respectively, the corresponding splitting tensile strength of concrete reaches the maximum value(3.4 and 3.7 MPa). The contribution rates of nano-TiO2 and PPF with different volume contents to the mechanical properties of RAC have optimal values, which are 0.4 and 1.0%, respectively. The incorporation of nano-TiO2 and PPF can effectively inhibit the loss of RAC mass and the generation of pores under freeze–thaw conditions, and slow down the decrease of dynamic elastic modulus. When the volume content of PPF is 1.0% and the volume content of nano-TiO2 is 0.4%, the protection effect on the internal structure of RAC is better, and its carbon resistance is better. The results of RSM model analysis and prediction show that both PPF and nano-TiO2 can be used as admixture materials to improve the mechanical properties and durability of RAC, and the comprehensive improvement effect of PPF on RAC performance is better than that of nano-TiO2.

Microfluidic Electroporation Arrays for Investigating Electroporation-Induced Cellular Rupture Dynamics.

Electroporation is pivotal in bioelectrochemistry for cellular manipulation, with prominent applications in drug delivery and cell membrane studies. A comprehensive understanding of pore generation requires an in-depth analysis of the critical pore size and the corresponding energy barrier at the onset of cell rupture. However, many studies have been limited to basic models such as artificial membranes or theoretical simulations. Challenging this paradigm, our study pioneers using a microfluidic electroporation chip array. This tool subjects live breast cancer cell species to a diverse spectrum of alternating current electric field conditions, driving electroporation-induced cell rupture. We conclusively determined the rupture voltages across varying applied voltage loading rates, enabling an unprecedented characterization of electric cell rupture dynamics encompassing critical pore radius and energy barrier. Further bolstering our investigation, we probed cells subjected to cholesterol depletion via methyl-β-cyclodextrin and revealed a strong correlation with electroporation. This work not only elucidates the dynamics of electric rupture in live cell membranes but also sets a robust foundation for future explorations into the mechanisms and energetics of live cell electroporation.

Volumetric Additive Manufacturing of SiOC by Xolography.

Additive manufacturing (AM) of ceramics has significantly contributed to advancements in ceramic fabrication, solving some of the difficulties of conventional ceramic processing and providing additional possibilities for the structure and function of components. However, defects induced by the layer-by-layer approach on which traditional AM techniques are based still constitute a challenge to address. This study presents the volumetric AM of a SiOC ceramic from a preceramic polymer using xolography, a linear volumetric AM process that allows to avoid the staircase effect typical of other vat photopolymerization techniques. Besides optimizing the trade-off between preceramic polymer content and transmittance, a pore generator is introduced to create transient channels for gas release before decomposition of the organic constituents and moieties, resulting in crack-free solid ceramic structures even at low ceramic yield. Formulation optimization alleviated sinking of printed parts during printing and prevented shape distortion. Complexsolid and porous ceramic structures with a smooth surface and sharp features are fabricated under the optimized parameters. This work provides a new method for the AM of ceramics at µm/mm scale with high surface quality and large geometry variety in an efficient way, opening the possibility for applications in fields such as micromechanical systems and microelectronic components.