Varying Pore Size Research Articles

Synthesis of Porous Anodic Alumina Featuring a Periodic Pore Structure by Regulating the Anode Temperature

Abstract Porous anodic alumina (PAA) with a periodic pore structure has been synthesized by using an innovative preparation method. The morphology of PAA pores can be modulated within the same electrolyte by adjusting the temperature of the aluminum anode, enabling periodic variations in pore size (Dp). The formation mechanism of PAA has been elucidated through analyses of micromorphology, anodization current density (ia), interpore distance (Dint), and Dp of the samples. Results indicate that the average Dint for the synthesized PAA is approximately 260–340 nm, while the average Dp ranges from 90 to 260 nm. Both ia and Dp exhibit periodic fluctuations corresponding to changes in anode temperature under consistent electrolyte conditions and anodization voltage (Ua). Lateral pores are generated via a phosphoric acid etching process, resulting in PAA with a distinctive three-dimensional interconnected pore architecture. Furthermore, ridges with an arc-like shape on the outer walls of PAA pores have been observed; their formation mechanism can be effectively explained by the convection model and the viscous flow model. These findings contribute significantly to achieving precise control over the pore structure of PAA.

3D printed β-TCP scaffolds loaded with SVVYGLR peptide for promoting revascularization and osteoinduction

It is crucial for the successful transplantation of large segmental bone defects to achieve rapid vascularization within bone scaffolds. However, there are certain limitations including uncontrolled angiogenesis and inadequate vascular function. Therefore, there is an urgent need to develop bone scaffolds with functional vascular networks. In our study, porousβ-tricalcium phosphate (β-TCP) scaffolds with varying pore sizes were prepared by 3D printing technology, loaded with osteopontin derived peptide Ser-Val-Val-Tyr-Gly-Leu-Arg (SVVYGLR) to induce osteoinduction and angiogenesis.In vitro, the proliferation and migration behaviors of human umbilical vein endothelial cell on scaffolds were assessed by Cell Counting Kit-8, confocal laser scanning microscopy and scanning electron microscopy. And the osteogenic ability of bone marrow mesenchymal stem cells was assessed using alkaline phosphatase staining and Alizarin Red S staining. The messenger ribonucleic acid (mRNA) expression levels of cell adhesion molecule (CD31), vascular endothelial growth factor and hypoxia inducible factor-1αin each group were detected by quantitative real-time fluorescence polymerase chain reaction (PCR) analysis.In vivo, cube scaffolds were subcutaneously implanted on the right hips of Sprague-Dawley (SD) rats for 6 weeks. Hematoxylin and Eosin staining, Masson's trichrome staining, and immunohistochemical analysis of osteocalcin and CD31 were performed on slices for every sample with three sections to explore the effect of SVVYGLR-loaded scaffolds on angiogenesis and osteogenic induction for bone reconstruction. The results indicate that 3D printedβ-TCP scaffolds loaded with the SVVYGLR peptide offer superior revascularization and osteoinduction to the scaffolds without the SVVYGLRin situ. Moreover, scaffolds with a pore size of 400 µm demonstrate higher effectiveness compared to those with a 150 µm pore size. The distinct hollow channel scaffolds and the specific SVVYGLR peptide substantially improve cell adhesion, spreading, and proliferation, as well as promote angiogenesis and bone formation. Furthermore, scaffolds with a pore size of 400 µm may exhibit greater efficacy compared to those with a pore size of 150 µm. The results of this study provide an idea for the development of practical applications for tissue-engineered bone scaffolds.

Droplet sizes and delivery rates from film breakup aerosolisation mode in porous materials

Abstract A novel two-phase aerosolisation mode utilizing porous materials is investigated, aiming to improve aerosol delivery for medical inhalation. Sintered stainless steel filters with varied pore sizes (PS) from 0.2 μm to 7 μm were used to generate aerosols from a 0.9 wt.% sodium chloride solution. Droplet sizes and delivery rates were measured using laser diffraction spectroscopy. Further measurements included shadow imaging. Results indicate that aerosolisation occurs within a specific range of PS with droplet sizes increasing with increasing PS. The droplets generated are suitable for inhalation therapies. A hypothesis is established about the process of droplet formation which states that different PS within the porous material serve distinct functions that contribute to the breakup of liquid films into aerosol particles. Droplet formation is the result of film breakup in pores filled with fluid. This low-energy aerosolisation method has the potential to be used in handheld devices for sensitive drug formulations, overcoming the limitations of current technologies. Further research is needed to optimize the pore size distribution and enhance aerosol generation efficiency.

Removal of pharmaceutical compounds from sewage effluent by the nanofiltration membrane

Membrane is a promising technology for water treatment, and its commercial production has emerged globally. However, commercial membranes' effectiveness is still uncertain due to the new types of contaminants, such as pharmaceutical compounds (PC). Thus, in the current work, the performance of two commercial membranes (NFX and GC) has been evaluated using feed water from the effluent of sewage treatment plants (STP) and hospital wastewater (HWW). The spiked feed water contains PC classes of analgesics/anti-inflammatory, anti-hypertensives, beta-blockers, and psychiatric/antidepressants. The percentage difference between feed and permeate was measured. While the fouling properties of the membranes are also evaluated using STP and HWW as feed, along with the pure water flux in a variable-pressure setting, the results showed that NFX exhibits excellent, consistent rejection for the targeted PCs (>80 %). GC showed a broader range of rejection (10 % to 90 %) and presented a better flux flow than NFX. The main rejection factor is due to the membrane's pore size variation and the layer construction, which refer to the absorption, size exclusion, and diffusion of the PCs instead of the type of feed water and the flux. Current work provides scientific data on the diverse fabrication and market-available types of membranes, which would pose various efficiencies towards the type of targeted pollution.

Initial biological evaluation of nanofiber and microwire biomaterials

Abstract Due to the direct long-term contact with living tissue, the biocompatibility of implants is particularly demanding. In this context, biointegration of implants highly depends on cell colonialization on the surface or in the gap between implant and tissue, as well as cell ingrowth in porous implant structures. Fibrous material is predestined based on two variable parameters, fiber thickness and pore size. Various applications in implant coating, stenting, wound treatment, bone surgery, or cardiovascular field are possible. Coating with cell-friendly material can significantly improve the biocompatibility of the underlying material. In this study, the biocompatibility of medical device samples made of microwire and nanofiber substrates was compared according to ISO 10993-5. In particular, a metal tissue of microwire (stainless steel, 316L) and polymeric nanofiber nonwoven poly-L-lactic acid (PLLA) as well as titanium (Ti) sputtered variants thereof (316L-Ti, PLLA-Ti) were tested in vitro. In order to evaluate their environmental compatibility and their effects on L929 cell line (murine fibroblasts) evaluation was performed via direct contact with 30,000 cells per 48-well in non-adherent plates for 48 h and 96 h. The metabolic activity of cells was determined via CellQuanti-Blue assay, morphological analysis were done using fluorescence staining phalloidin and DAPI. Briefly outlined, microwires were colonized immediately, whereas initially spherical cells settled on nanofiber substrates and later coalesced forming a common cell cluster. The results show independency of structure, ultrathin titanium coating improves cell viability. The findings indicate that the idea of making a surface appealing to cells has potential. It can therefore be assumed that physical vapor deposition (PVD) sputtering of Ti on implant surfaces is a suitable approach to maintain or improve their biocompatibility, regardless of the surface structure of the implants.

Mechanical behavior of clayey methane hydrate-bearing sediment: Effects of pore size and physicochemical characteristics using a novel DEM contact model

The mechanical behavior of Methane Hydrate-Bearing Sediment (MHBS) is essential for the safe exploitation of Methane Hydrate (MH). In particular, the pore size and physicochemical characteristics of MHBS significantly influence its mechanical behavior, especially in clayey grain-cementing type MHBS. This study employs the Distinct Element Method (DEM) to investigate both the macroscopic and microscopic mechanical behavior of clayey grain-cementing type MHBS, focusing on variations in pore size and physicochemical characteristics. To accomplish this, we propose a Thermo-Hydro-Mechanical-Chemical-Soil Characteristics (THMCS) DEM contact model that incorporates the effects of pore size and physicochemical characteristics on the strength and modulus of MH. This THMCS model is validated using experimental data available in the literature. Using the proposed contact model, we conducted a series of investigations to explore the mechanical behavior of MHBS under conventional loading paths, including isotropic and drained triaxial tests using the DEM. The numerical results indicate that smaller pore sizes and lower water content—key physicochemical characteristics resulting from variations in electrochemical properties and the intensity of the electric field—can lead to reduced shear strength and stiffness due to the increased breakage of aggregates and weakened cementation. Additionally, heating was found to further accelerate the process of structural damage in MHBS.

All-in-one dual-function porous materials derived from polyacrylonitrile for high-performance supercapacitor

Polyacrylonitrile (PAN)-based multifunctional energy storage materials have garnered significant interest in the research community. However, developing multifunctional PAN porous materials for integrated supercapacitors has encountered challenges such as low energy density, insufficient separator wettability, and limited ion conductivity. Herein, two types of versatile PAN-based dual-function porous membranes with varying pore sizes were fabricated using straightforward techniques involving solvent exchange and a directed freezing freeze-drying process. Subsequently, a high-performance-separator (POS) was developed by modifying pristine porous PAN with tetraethoxysilane (TEOS). Energy storage materials (CPAN-MnO2) were fabricated by depositing MnO2 onto the porous carbonised PAN (CPAN) surface through electrodeposition. The resulting structure, with CPAN-MnO2 as the energy storage unit and POS as the separator, achieved an impressive ion conductivity of 32.2 mS cm−1, super hydrophilicity, and high electrolyte uptake (456 %) and retention (302 %). A symmetric supercapacitor (SC) using CPAN-MnO2 and POS demonstrated a maximum energy density of 163 μWh cm−2 and exceptional cyclic stability, with 93.6 % capacitance retention after 10,000 cycles. This superior energy storage performance can be attributed to the TEOS-modified PAN porous channels, which enhance wettability with the electrolyte, improving electrolyte uptake and retention within the porous framework for ion exchange, thereby enhancing the electrochemical performance.

Controlling CO2 and H2o Mass Transport in Gas Diffusion Electrodes for CO2 Reduction by Acting on the Substrate

Electrochemical CO2 reduction (eCO2R) is a very promising way to convert detrimental CO2 emissions into sustainable fuels and chemicals, and move us closer to a net zero or net negative carbon economy. 1 To compete with traditional fuel/chemical production routes, electrocatalysts needs to be highly active, selective towards a desired product, and stable. Thanks to the use of gas diffusion electrodes (GDEs) that provide gaseous CO2 close to the electrocatalyst, high activities can be achieved. 2 However, product selectivity as well as stability still need to be improved before applications. An emerging strategy to drive product selectivity and improve stability is to control the local environment surrounding an electrocatalyst, i.e., the concentration of the products and reagents therein.3 In this work, we achieve such control by tuning the mass transport of the eCO2R reactants, namely CO2 and H2O, to the reaction sites by varying pore size and hydrophobicity of polymeric GDE substrates coated with Ag or Cu electrocatalysts.4,5 We show that for GDEs with large pore size and weak hydrophobicity, a deeper penetration of water/ aqueous electrolyte takes place, yielding, in the Ag case, poor selectivity towards CO and a significant production of H2. In contrast, GDEs with small pore size prevent this local flooding of the electrocatalyst, thus yielding a greatly improved Faradaic efficiency towards CO (up to 95% at 100 mA/cm2 in neutral electrolyte), minimal H2 evolution, and remarkable long-term stability (97% of initial CO selectivity retained after > 40 h).4 In the Cu case, we observe a strong enhancement in C2H4 selectivity when employing GDE substrates with small pores and strong hydrophobicity (up to 50% Faradaic efficiency in neutral electrolyte at 200 mA/cm2 for > 3 h).5 Both CO2 and CO reduction experiments on Cu GDEs indicate the presence of mass transport limitations for the gaseous reactants in all GDEs, however this limitation is less severe for GDEs with small pore sizes. We rationalize these findings with the presence of an electrolyte layer covering the electrocatalyst, forcing the electrocatalytic reaction to take place at double phase boundaries. Under these conditions, CO2 mass transport limitations are governed by the extent of electrolyte penetration within the GDE and can thus be controlled by acting on the substrate.4,5 In addition to fundamental understanding, our results also provide a scalable strategy to improve product selectivity and stability of GDEs for eCO2R. References 1Senocrate, A.; Battaglia, C.; J. Energy Storage 2021, 36, 102373. 2García de Arquer, F. P.; Dinh, C.-T.; Ozden, A.; Wicks, J.; McCallum, C.; Kirmani, A. R.; Nam, D.-H.; Gabardo, C.; Seifitokaldani, A.; Wang, X.; Li, Y. C.; Li, F.; Edwards, J.; Richter, L. J.; Thorpe, S. J.; Sinton, D.; Sargent, E. H. Science 2020, 367, 661–666. 3Veenstra, F.; Ackerl, N.; Martín, A.; Pérez-Ramírez, J.; Chem 2020, 1–16. 4Senocrate, A.; Bernasconi, F.; Rentsch, D.; Kraft, K.; Trottmann, M.; Wichser, A.; Bleiner, D.; Battaglia, C.; ACS Appl. Energy Mater. 2022, 5, 14504. 5Bernasconi, F.; Senocrate, A.; Kraus, P.; Battaglia, C.; EES Catalysis 2023, 1, 1009.

Fabrication of Nanopillar Arrays with Wettability Gradients by Nanoimprinting Using Anodic Porous Alumina Molds

When water droplets form on a surface with a continuously changing wettability, they spontaneously move from a higher to a lower water droplet contact angle. Such wettability gradient surfaces are expected to have a variety of applications, including analytical chips that do not require pumps. We previously reported that the formation of a wettability gradient surface is possible by continuously varying the pore size of anodic porous alumina obtained by the anodization of an Al substrate [1,2]. In this report, we describe the formation of nanopillar arrays with a wettability gradient by nanoimprinting using anodic porous alumina with continuously varying pore sizes. The results of the evaluation of the transport distance of water droplets formed on the surface of the resulting nanopillar arrays are also shown. This method makes it possible to impart wettability gradient properties to various substrate surfaces. Ideally ordered anodic porous alumina with an interpore distance of 1 μm was obtained by the anodization of an Al substrate. The resulting anodic porous alumina was immersed in phosphoric acid solution at a constant speed to produce a hole array structure with continuously varying pore sizes. Polymer nanopillar arrays with continuously varying diameters were obtained on glass substrates by nanoimprinting using the resulting anodic porous alumina as a mold. The surfaces of the resulting polymer pillar arrays were hydrophobically treated, and the contact angles of the water droplets were measured. Water droplets were formed on the surface of the polymer pillar array, and the spontaneous transport distance of water droplets was measured. SEM observations showed that polymer pillar arrays with continuously changing diameters were formed via nanoimprinting. From the contact angle measurements, it was confirmed that the contact angle changed continuously as the diameter of the nanopillars changed. When water droplets formed on the surface of the nanopillar arrays, spontaneous movement of the droplets was observed. This method is effective as a surface treatment for the spontaneous transport of water droplets on various substrate surfaces.

Controlled release of mesenchymal stem cell-derived nanovesicles through glucose- and reactive oxygen species-responsive hydrogels accelerates diabetic wound healing

Wound healing is often impaired in patients with diabetes. Mesenchymal stem cells (MSCs) and MSCs-derived nanovesicles (MNVs) hold promise as therapeutic agents for managing diabetic wounds. However, efficient delivery and controlled release of MNVs within these wounds are essential for maximizing therapeutic effectiveness. In this study, we developed a dual-responsive hydrogel designed to respond to elevated levels of glucose and reactive oxygen species. This hydrogel combines polyvinyl alcohol with phenylboronic acid-grafted chitosan, referred to as PBA-CP, while MNVs were produced by shearing MSCs through membranes with varying pore sizes. The composite PBA-CP/MNVs hydrogel significantly accelerated wound healing in a diabetic wound model by promoting epithelialization, dermal reconstruction, hair follicle formation, and angiogenesis. MNVs were readily taken up by keratinocytes, fibroblasts, and endothelial cells, stimulating their proliferation and migration. Altogether, the chitosan-based PBA-CP/MNVs composite hydrogel presents a promising therapeutic strategy for diabetic wound treatment.

Experiment and simulation of the interfacial joining mechanism for the strong polyformaldehyde-aluminum alloy hybrids

Using polymer-metal hybrids offers a promising energy conservation and emission reduction approach. In this investigation, nanoporous structures with varying pore sizes were synthesized on the surface of aluminum (Al) by adjusting the oxidation duration. Then, aluminum was bonded with polyformaldehyde (POM) using a hot pressing technique. An increase in nanopore size resulted in enhanced surface roughness and wettability of the Al, thereby promoting the embedding of POM into the Al surface and subsequently improving the mechanical interlocking capability at the interface. The embedding depth of POM with varying pore sizes was analyzed using atomic force microscopy (AFM). Additionally, a flow model of POM within nanopores was developed using the finite element method, and the calculated diffusion depths were consistent with the experimental results. The embedding depth reached 2.38 μm when the pore size was approximately 100 nm, at which point the interface achieved the optimal filling ratio. Furthermore, the interface was examined using X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT), revealing the presence of an Al-O-C chemical bond. The maximum joining strength of the POM-Al hybrid reached 42.56 MPa, and the failure mode was a mixed failure mode of interfacial failure and cohesive failure. In summary, these results are crucial for further designing and optimizing polymer-metal hybrids prepared using anodic oxidation.

Impact of Pore Diameter on Heat Conduction Efficiency in Porous Media Based on Ansys

Abstract. To help advance the development of heat dissipation technologies, the research studies the effect of pore diameter on heat conduction within porous media. With the help of Ansys software, a cuboid with varying pore sizes is modelled to investigate its influence on effective thermal conductivity. Through analysing the data exported, an overall trend is derived: for a fixed number of nodes in a piece of porous material, the efficiency of heat conduction tends to be higher with the increase of pore sizes. The study is especially relevant for the design of radiators with porous plates, commonly used in cooling systems. Larger pores tend to facilitate more gas-phase conduction, which, when combined with solid-phase conduction, optimizes overall thermal conductivity. The results of the study can potentially advance the development of heat dissipation technologies.

Unveiling the pore size change in polyamide membrane using aggregation induced emission

Polyamide (PA) membranes play a crucial role in nanofiltration and reverse osmosis separations, while their pore size is primary to determine the separation performance. Current methods for pore size analysis, such as atomic force microscopy (AFM), positron annihilation spectroscopy (PAS), and the filtration experiment of neutral molecules are time-consuming and lack real-time capabilities. This limitation hinders in-situ monitoring of pore size dynamics under various operating conditions. Therefore, a rapid and real-time method is highly desirable for pore size analysis. This work presents a novel approach for real-time detection of pore size variations in PA membranes under different solvent conditions. It utilizes aggregation-induced emission (AIE) with tetraphenylethylene (TPE) groups covalently linked to the PA polymer chain during interfacial polymerization using 1-(4-Aminophenyl)-1,2,2-triphenylethene as a co-monomer. Fluorescence intensity of the PA membrane serves as an indicator of the confined state of the TPE molecules within the polymer network, thereby reflecting pore size changes under various conditions. The accuracy of the AIE-based approach is validated through complementary analyses such as small-angle X-ray scattering (SAXS) and rejection of dye molecules. The observed consistency between fluorescence variations in the PA membrane and pore size changes under different solvent conditions confirms the effectiveness of this method. This work provides a valuable visual tool for in-situ monitoring of pore size dynamics in polyamide membranes.

Understanding the impact of nickel coating on the mechanical and corrosion behaviour of copper foams

ABSTRACT This study used a sponge replication technique to fabricate open-cell copper (Cu) foams with varying pore sizes. Nickel coating was applied via electrolysis to produce nickel-copper (NiCu) foams to enhance the Cu foams' energy absorption efficiency and corrosion resistance. The foams were characterized under static conditions to assess their compressive and corrosion properties. The nickel coating improved compressive strength by increasing foam strut thickness and reducing defects, as observed via scanning electron microscopy (SEM). The 10 Pores per inch (PPI) NiCu foam shows a substantial increase in compressive strength, close to 17.7%, compared to the 10 PPI Cu foam, resulting in a maximum compressive strength of 11.3 MPa. Similarly, 20PPI NiCu foam shows an increase of compressive strength of 20% when compared to 20 PPI Cu foam. NiCu foams significantly reduced corrosion current density compared to uncoated Cu foams, indicating enhanced corrosion protection from the nickel coating.

Hyperelastic constitutive relations for porous materials with initial stress

Initial stress is widely observed in porous materials. However, its constitutive theory remains unknown due to the lack of a framework for modeling the interactions between initial stress and porosity. In this study, we construct the porous hyperelastic constitutive model with arbitrary initial stresses through the multiplicative decomposition approach. Based on the compression experiment of shale samples, the parameters in the constitutive equation are determined. Then, the explicit equations of in-plane elastic coefficients are proposed by linearizing the finite deformation formulation. The influences brought by the coexistence of initial stresses and porosity on these coefficients are revealed. Later, comparative analyses of the linearized equations between the present model, the initially-stressed models without pores, the Biot poroelasticity, and the porous hyperelastic model without initial stress are conducted to illustrate the performances of the two ingredients. As a specific example, we investigate the variation of pore sizes under external pressures and initial stresses since changes in pore sizes during deformation are crucial for understanding the accumulation and migration of shale oil and gas. The newly proposed model provides the first initially stressed porous hyperelasticity (ISPH), which is suitable for describing the finite deformation behavior of solid materials with large porosity and significant initial stress simultaneously.

A pH-Responsive Hydrogel for the Oral Delivery of Ursolic Acid: A Pentacyclic Triterpenoid Phytochemical.

In this study, poly(HEMA-PEGxMEM-IA) hydrogels were prepared by radical copolymerization of poly(ethylene glycol) methyl ether methacrylate (PEGxMEM), 2-hydroxyethyl methacrylate (HEMA), and itaconic acid (IA). The reaction was carried out in ethanolic solution using N,N'-methylenebisacrylamide (MBA) as a crosslinking agent and 1-hydroxycyclohexyl phenyl ketone (HCPK) as a photo-initiator. The poly(HEMA-PEGxMEM-IA) hydrogels (HGx) were evaluated as a delivery system for ursolic acid (UA), a phytochemical extracted from the plant Clinopodium revolutum, "flor de arena". The hydrogels were characterized by Fourier-transform infrared spectroscopy (FTIR-ATR), Raman spectroscopy, X-Ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The swelling behavior was studied in buffer solutions from pH 2 to 10, specifically at pH 2.2 (gastric environment) and 7.4 (intestinal environment). It was found that the hydrogels studied showed sensitivity to pH. At pH 2.2, the degree of swelling for HG5 and HG9 hydrogels was 0.45 and 0.93 (g water/g hydrogel), respectively. At pH 7.4, the degree of swelling for HG5 and HG9 hydrogels was 1.97 and 2.64 (g water/g hydrogel), respectively. The SEM images show the variation in pore size as a function of pH, and the UA crystals in the pores of the hydrogels can also be observed. The in vitro UA release data best fit the Korsmeyer-Peppas kinetic model and the diffusion exponent indicates that the release mechanism is governed by Fickian diffusion.

Multi-parametric Photoacoustic Imaging Combined with Acoustic Radiation Force Impulse Imaging for Applications in Tissue Engineering.

Tissue engineering is a dynamic field focusing on the creation of advanced scaffolds for tissue and organ regeneration. These scaffolds are customized to their specific applications and are often designed to be complex, large structures to mimic tissues and organs. This study addresses the critical challenge of effectively characterizing these thick, optically opaque scaffolds that traditional imaging methods fail to fully image due to their optical limitations. We introduce a novel multi-modal imaging approach combining ultrasound, photoacoustic, and acoustic radiation force impulse imaging. This combination leverages its acoustic-based detection to overcome the limitations posed by optical imaging techniques. Ultrasound imaging is employed to monitor the scaffold structure, photoacoustic imaging is employed to monitor cell proliferation, and acoustic radiation force impulse imaging is employed to evaluate the homogeneity of scaffold stiffness. We applied this integrated imaging system to analyze melanoma cell growth within silk fibroin protein scaffolds with varying pore sizes and therefore stiffness over different cell incubation periods. Among various materials, silk fibroin was chosen for its unique combination of features including biocompatibility, tunable mechanical properties, and structural porosity which supports extensive cell proliferation. The results provide a detailed mesoscale view of the scaffolds' internal structure, including cell penetration depth and biomechanical properties. Our findings demonstrate that the developed multimodal imaging technique offers comprehensive insights into the physical and biological dynamics of tissue-engineered scaffolds. As the field of tissue engineering continues to advance, the importance of non-ionizing and non-invasive imaging systems becomes increasingly evident, and by facilitating a deeper understanding and better characterization of scaffold architectures, such imaging systems are pivotal in driving the success of future tissue-engineering solutions.

Assessment of the physiochemical properties and sustainability of locally produced ceramic G-filter in a long term experiment

In India, Ceramic Water Filters (CWF) named G-filters are becoming a point-of-use household water treatment solution. The filter's reliability may be primarily characterized by the filtrate turbidity and microbial removal efficiency. The temperature and moisture gradients of the location affect its performance. This paper describes a 19-week laboratory investigation of G-filters simulating field conditions. The basic objective during the study was to ascertain the effective useable life of the filter. The discharge rate and turbidity reduction ability of the filters are studied in depth. The G-filters were prepared using locally available salty clay and sawdust taken in equal volume fractions. A total of 30 filters with a 9-liter capacity each were used for the experiments. The results showed that CWFs can reduce turbidity effectively. The influent water used for the study had a mean turbidity of 7.65 NTU, which reduced in the range of 0.03 NTU to 1.03 NTU. Over the course of four months, the average flow rate decreased from 1.94 Lh-1 to 0.93 Lh-1. Although a soft brushing of filters improved the filtration rate but that too failed in the long run. Brunauer–Emmett–Teller (BET) nitrogen adsorption–desorption measurements were used to determine the variation in pore size of filters with time. An average pore radius of 2.91 nm was found in the original filter that has not been used for filtration experiments. Moreover, an average pore radius of 1.77 nm, 1.21 nm, and 1.22 nm were reported in G-filters through which 427.5 L, 807.5 L, and 1035.5 L, respectively, of water were passed. This reduction in pore size is attributed to the clogging of pores over a period of time. This study aims to collect performance data to establish a scientific model using statistical analysis for implementing CWF technology in developing nations.

Comparison In Vitro Study on the Interface between Skin and Bone Cell Cultures and Microporous Titanium Samples Manufactured with 3D Printing Technology Versus Sintered Samples.

Percutaneous implants osseointegrated into the residuum of a person with limb amputation need to provide mechanical stability and protection against infections. Although significant progress has been made in the biointegration of percutaneous implants, the problem of forming a reliable natural barrier at the level of the surface of the implant and the skin and bone tissues remains unresolved. The use of a microporous implant structure incorporated into the Skin and Bone Integrated Pylon (SBIP) should address the issue by allowing soft and bone tissues to grow directly into the implant structure itself, which, in turn, should form a reliable barrier to infections and support strong osseointegration. To evaluate biological interactions between dermal fibroblasts and MC3T3-E1 osteoblasts in vitro, small titanium discs (with varying pore sizes and volume fractions to achieve deep porosity) were fabricated via 3D printing and sintering. The cell viability MTT assay demonstrated low cytotoxicity for cells co-cultured in the pores of the 3D-printed and sintered Ti samples during the 14-day follow-up period. A subsequent Quantitative Real-Time Polymerase Chain Reaction (RT-PCR) analysis of the relative gene expression of biomarkers that are associated with cell adhesion (α2, α5, αV, and β1 integrins) and extracellular matrix components (fibronectin, vitronectin, type I collagen) demonstrated that micropore sizes ranging from 200 to 500 µm of the 3D printed and sintered Ti discs were favorable for dermal fibroblast adhesion. For example, for representative 3D-printed Ti sample S6 at 72 h the values were 4.71 ± 0.08 (α2 integrin), 4.96 ± 0.08 (α5 integrin), 4.71 ± 0.08 (αV integrin), and 1.87 ± 0.12 (β1 integrin). In contrast, Ti discs with pore sizes ranging from 400 to 800 µm demonstrated the best results (in terms of marker expression related to osteogenic differentiation, including osteopontin, osteonectin, osteocalcin, TGF-β1, and SMAD4) for MC3T3-E1 cells. For example, for the representative 3D sample S4 on day 14, the marker levels were 11.19 ± 0.77 (osteopontin), 7.15 ± 0.29 (osteonectin), and 6.08 ± 0.12 (osteocalcin), while for sintered samples the levels of markers constituted 5.85 ± 0.4 (osteopontin), 4.45 ± 0.36 (osteonectin), and 4.46 ± 0.3 (osteocalcin). In conclusion, the data obtained show the high biointegrative properties of porous titanium structures, while the ability to implement several pore options in one structure using 3D printing makes it possible to create personalized implants for the best one-time integration with both skin and bone tissues.

A Double-Layer Polyurethane Electrospun Membrane with Directional Sweat Transport Ability for Use as a Soft Strain Sensor.

Wearable electronics for long-term monitoring of physiological signals should be capable of removing sweat generated during daily motion, which significantly impacts signal stability, human comfort, and safety of the electronics. In this study, we developed a double-layer polyurethane (PU) membrane with sweat-directional transport ability that can be applied for monitoring strain signals. The PU membrane was composed of a hydrophilic, conductive layer and a relatively hydrophobic layer. The double-layer PU composite membrane exhibited varied pore size and opposite hydrophilicity on its two sides, enabling the spontaneous pumping of sweat from the hydrophobic side to the hydrophilic side, i.e., the directional transport of sweat. The membrane can be used as a strain sensor to monitor motion strain over a broad working range of 0% to 250% with high sensitivity (GF = 4.11). The sensor can also detect simple human movements even under sweating conditions. We believe that the strategy demonstrated here will provide new insights into the design of next-generation strain sensors.