Porous Metal Research Articles

Three-dimensional porous bimetallic metal–organic framework/gelatin aerogels: A readily recyclable peroxymonosulfate activator for efficient and continuous organic dye removal

Three-dimensional porous bimetallic metal–organic framework/gelatin aerogels: A readily recyclable peroxymonosulfate activator for efficient and continuous organic dye removal

Reconstruction of Paprosky IIIB acetabular defects with porous tantalum shells and augments using the footing technique.

The use of a porous metal shell supported by two augments with the 'footing' technique is one solution to manage Paprosky IIIB acetabular defects in revision total hip arthroplasty. The aim of this study was to assess the medium-term implant survival and radiological and clinical outcomes of this technique. We undertook a retrospective, two-centre series of 39 hips in 39 patients (15 male, 24 female) treated with the 'footing' technique for Paprosky IIIB acetabular defects between 2007 and 2020. The median age at the time of surgery was 64.4 years (interquartile range (IQR) 54.4 to 71.0). The median follow-up was 3.9 years (IQR 3.1 to 7.0). The cumulative medium-term survival of the acetabular construct was 89%. Two hips (5.1%) required further revision due to shell loosening, one hip (2.6%) due to shell dislocation, and one hip (2.6%) due to infection. The median Harris Hip Score improved significantly from 47 points (IQR 41.5 to 54.9) preoperatively to 80 points (IQR 73.5 to 88.6) at the latest follow-up (p < 0.001). The reconstruction of Paprosky IIIB acetabular defects with porous tantalum shells and two augments using the 'footing' technique showed excellent medium-term results. It is a viable option for treating these challenging defects.

Can a reconstruction algorithm in major acetabular bone loss be successful in revision hip arthroplasty?

The aims of this study were to determine the success of a reconstruction algorithm used in major acetabular bone loss, and to further define the indications for custom-made implants in major acetabular bone loss. We reviewed a consecutive series of Paprosky type III acetabular defects treated according to a reconstruction algorithm. IIIA defects were planned to use a superior augment and hemispherical acetabular component. IIIB defects were planned to receive either a hemispherical acetabular component plus augments, a cup-cage reconstruction, or a custom-made implant. We used national digital health records and registry reports to identify any reoperation or re-revision procedure and Oxford Hip Score (OHS) for patient-reported outcomes. Implant survival was determined via Kaplan-Meier analysis. A total of 105 procedures were carried out in 100 patients (five bilateral) with a mean age of 73 years (42 to 94). In the IIIA defects treated, 72.0% (36 of 50) required a porous metal augment; the remaining 14 patients were treated with a hemispherical acetabular component alone. In the IIIB defects, 63.6% (35 of 55) underwent reconstruction as planned with 20 patients who actually required a hemispherical acetabular component alone. At mean follow-up of 7.6 years, survival was 94.3% (95% confidence interval 97.4 to 88.1) for all-cause revision and the overall dislocation rate was 3.8% (4 of 105). There was no difference observed in survival between type IIIA and type IIIB defects and whether a hemispherical implant alone was used for the reconstruction or not. The mean gain in OHS was 16 points. Custom-made implants were only used in six cases, in patients with either a mega-defect in which the anteroposterior diameter > 80 mm, complex pelvic discontinuity, and massive bone loss in a small pelvis. Our findings suggest that a reconstruction algorithm can provide a successful approach to reconstruction in major acetabular bone loss. The use of custom implants has been defined in this series and accounts for < 5% of cases.

Metal-organic framework gel derived magnetic hierarchical porous Fe-N-C catalyst as peroxymonosulfate activator for efficient degradation of amoxicillin via singlet oxygen-dominated nonradical pathway

The rational design of transition metal and nitrogen co-doped carbon-based catalysts for the efficient removal of antibiotics through non-radical pathway of peroxymonosulfate (PMS) activation has attracted widespread attention. Herein, a magnetic hierarchical porous Fe-N-C catalyst (FeBDC-NH2-800) was successfully constructed by pyrolyzing the hierarchical porous precursor metal–organic framework gel (FeBDC-NH2) consisting of nitrogen-containing ligands. Benefiting from the defective heterojunction structure, the catalyst exhibited effective and efficient degradation towards amoxicillin (AMX) by activating PMS to produce 1O2. The degradation of AMX was up to 97.4 % within 30 min, which was 2.48 and 2.16 times more than that of FeBDC-NH2/PMS and nanosized Fe3O4/PMS respectively. The high degradation performance could be maintained toward low pollutant concentration conditions and cycle experiments, manifesting its possibility for practical application. Combining the data of quenching experiments, electron spin resonance spectra, electrochemical experiments, X-ray photoelectron spectra and density functional theory calculation, the mechanism was revealed that radical pathway contributed little during degradation while singlet oxygen played a significant role. The cleavage of lattice oxygen and defective heterogeneous structure of FeBDC-NH2-800 contributed together to promote PMS for 1O2 production.

Overview of the application of open cell foam heat exchangers

PURPOSE. Review modern highly porous cellular heat exchangers. METHODS. We conducted a broad literature review on highly porous cellular structures used as heat exchangers. We studied both domestic and foreign literature. RESULTS. We analyzed highly porous heat exchangers of various structures: stochastic (foam with open and closed cells) and ordered (honeycombs and lattices). Methods for producing open/closed cell foams and additive technologies for producing honeycomb and lattice structures have been studied. The basic properties of highly porous structures are described. The factors influencing heat transfer and hydrodynamics in highly porous cellular heat exchangers are analyzed. A review of theapplication areas of highly porous metal heat exchangers is carried out. CONCLUSION. Heat transfer and hydrodynamics in highly porous materials depend on structural parameters, such as porosity, cell size and geometry, diameter, and geometry of the strands. Increasing porosity and cell size leads to a decrease in heat transfer coefficient and pressure drop. Changing the cell geometry affects the specific surface area of the heat exchanger and the pressure drop. Cells with complex geometries, such as octet, have a large surface area and provide a high heat transfer coefficient but high resistance to coolant flow. Cells with simple geometries, such as a cube, on the other hand, provide low flow resistance and low heat transfer coefficient. In general, any structural parameter change affects heat transfer and hydrodynamics.

The effect of topological design on the degradation behavior of additively manufactured porous zinc alloy

The advent of additively manufactured biodegradable porous metals presents a transformative opportunity to meet the criteria of ideal bone substitutes. Precisely tailoring their degradation behavior constitutes a pivotal aspect of this endeavor. In this study, we investigated the effects of topological designs on the degradation profile of laser powder bed fusion (LPBF) Zn scaffolds under dynamic in vitro immersion tests. Specifically, four types of Zn-0.4Mn-0.2Mg scaffolds (beam-based: diamond, face center cubic; surface-based: gyroid, schwarz-P) were designed and fabricated. The degradation mechanism of the scaffolds was comprehensively evaluated using both experimental and simulation methods. The results illuminate the profound impact of structural design on the degradation properties of the Zn alloy scaffolds. The beam-based diamond and face center cubic scaffolds exhibited a degradation rate of 0.08–0.12 mm per year with a relatively uniform degradation mode under dynamic immersion. On the contrary, the surface-based gyroid and Schwarz-P scaffolds demonstrated a notably reduced degradation rate due to lower permeability. This restricted the diffusion of medium ions within the pores, culminating in the accumulation of degradation products and more severe localized degradation. This study underscores the potential of topological design as a compelling strategy for tailoring the degradation profile of additively manufactured biodegradable scaffolds, thereby advancing their suitability as bone substitutes.

Numerical analysis of radiative transfer and prediction of spectral properties for combined material composed of nickel foam and TiO2 nanofluid

Accurate spectral radiative transfer simulation and property prediction are basic for improving the performance of combined collecting material in the field of solar photothermal utilization. In this work, the combined material composed of open-cell nickel foam and TiO2 nanofluid is proposed, and the various multi-scale structures are modeled. The realistic structures of nickel foams with different porosities and PPI are reconstructed with the μ-CT technique, meanwhile, the spherical nanoparticles with different radii are considered separately for modeling the structures of nanofluids with different particle sizes and volume fractions. A numerical simulation process is introduced for achieving the across-scale analysis, with the FDTD method and the MCRT method applied jointly. The numerical analysis integrating micro/nano-scale and macroscale radiative transfer processes is conducted for predicting the spectral radiative properties of nanofluid and combined material, with the complex size characteristics of nanoparticle, nanofluid and porous metal foam considered. Then, in the discussed waveband from 300 nm to 1000 nm, the absorption portions of different components are compared by changing the structural parameters at different scales. The effects of macro-scale and micro/nano-scale structural parameters on the spectral properties are analyzed. It can be observed that the extinction process inside nanofluid can be regulated by changing the particle size and volume fraction. Besides, in the discussed waveband, when the combined material with thickness exceeding 10 mm is applied, almost all the incident solar radiation can be absorbed. At last, the absorption performance is contributed by both nanofluid and solid foam, and the occupied portions of different components change with increasing wavelength. The absorption portions are affected by porosity, PPI, ligament surface morphology, nanoparticle size and volume fraction together.

Facile Construction of Stable Hierarchical Porous Metal–Organic Frameworks for In Situ Immobilization of β-Glucosidase Based on Competitive Coordination and Selective Etching Strategies

Facile Construction of Stable Hierarchical Porous Metal–Organic Frameworks for In Situ Immobilization of β-Glucosidase Based on Competitive Coordination and Selective Etching Strategies

Enhanced Heat Transfer in Thermoelectric Generator Heat Exchanger for Sustainable Cold Chain Logistics: Entropy and Exergy Analysis

This study investigates the application of thermoelectric power generation devices in conjunction with cold chain logistics transport vehicles, focusing on their efficiency and performance. Our experimental results highlight the impact of thermoelectric module characteristics, such as thermal conductivity and the filling thickness of copper foam, on the energy utilization efficiency of the system. The specific experimental setup involved a simulated logistics cold chain transport vehicle exhaust waste heat recovery thermoelectric power generation system, consisting of a high-temperature exhaust heat exchanger channel and two side cooling water tanks. Thermoelectric modules (TEMs) were installed between the heat exchanger and the water tanks to use the temperature difference and convert heat energy into electrical energy. The analysis demonstrates that using high-performance thermoelectric modules with a lower thermal conductivity results in better utilization of the temperature difference for power generation. Additionally, the insertion of porous metal copper foam within the heat exchanger channel enhances convective heat transfer, leading to an improved performance. Furthermore, the study examines the concepts of exergy and entropy generation, providing insights into the system energy conversion processes and efficiency. Overall, this research offers valuable insights for optimizing the design and operation of thermoelectric generators in cold chain logistics transport vehicles to enhance energy utilization and sustainability.

Large-Scale Synthesis of Highly Porous CuO/Cu2O/Cu/Carbon Derived from Aerogels for Lithium-Ion Battery Anodes.

In this work, an effective strategy for the large-scale fabrication of highly porous CuO/Cu2O/Cu/carbon (P-Cu-C) has been established. Cu-cross-linked aerogels were first continuously prepared using a continuous flow mode to form uniform beads, which were transformed into P-Cu-C with a subsequent pyrolysis process. Various pyrolysis temperatures were used to form a series of P-Cu-C including P-Cu-C-250, P-Cu-C-200, P-Cu-C-350, and P-Cu-C-450 to investigate suitable pyrolysis conversion processes. The obtained P-Cu-C series were utilized as anodes of lithium-ion batteries, in which P-Cu-C-250 exhibited a higher reversible gravimetric capacity, excellent rate capability, and superior cycle stability. The enhanced behavior of P-Cu-C-250 was benefitted from the synergistic interaction between uniformly dispersed CuO, Cu2O, Cu nanoparticles, and highly graphitized carbon with a large surface area and highly porous structure. More importantly, the preparation of P-Cu-C-250 could be scaled up by taking advantage of the continuous flow synthesis mode, which may provide pilot- or industrial-scale applications. The large-scale fabrication proposed here may give a universal method to fabricate highly porous metal oxide-carbon anode materials for electrochemical energy conversion and storage applications. Porous CuO/Cu2O/Cu/carbon derived from Cu-crosslinked aerogels was used as Li-ion battery anode materials, exhibiting a high reversible areal capacity, large gravimetric capacity, superior cycling performance, and excellent rate capacity. A continuous preparation method is established to ensure the product scaled up.

Study on the regulation mechanism of interfacial mechanical properties of carbon fiber reinforced aluminum foam sandwich interface

Carbon fiber (CF) is often used to enhance the interfacial properties of porous metal sandwich panel, however, the regulation mechanism on the mechanical properties of the reinforced interface is not clear, which affects its guidance in application. In this study, the regulation mechanism of CF on the mechanical properties of aluminum foam sandwich (AFS) interface was studied from the perspectives of morphology and chemistry. Results showed the effects of CF modification time, modification temperature and content on the interface properties were synergistic. The interfacial strength increased and decreased afterwards as the modification time or temperature or content increased. Fibers aggregation caused by excessive fiber addition could decrease the interface strength. Self-locking and fiber bridging were the dominant reinforced modes and their effects increased as appropriate addition content increased. Guided by the results, the shear strength of AFS interface increased by 79.18 %, the energy absorption increased by more than four times.

Multiphase flow dynamics in metal foam proton exchange membrane fuel cell

Porous metal foam holds substantial promise as a material for bipolar plates in high-performance proton exchange membrane fuel cells (PEMFC) due to its exceptional properties in reactant redistribution. However, the intricate structure of metal foam flow field (MFF) presents challenges for mass transfer and water management. In this study, a three-dimensional two-phase flow model for metal foam is developed to analyze and capture flow patterns. MFFs are reconstructed based on detailed structural analysis and various pore sizes are discussed. Employing the Volume of Fluid (VOF) method, we delve into multiphase flow dynamics, specifically focusing on the removal of liquid droplets within the MFF. It reveals the MFF with moderate pore sizes exhibit a trade-off performance, striking a balance between optimal mass transfer and minimal parasitic loss. The porous structure's pivotal role is highlighted, contributing significantly to both through-plane and in-plane mass transfer and convection. Furthermore, we classify three flow patterns of liquid droplet, with the “split-up” pattern emerging as the most effective for water management and mass transfer. This study illuminates water behavior in porous metal foam bipolar plates, introduces a systematic methodology for assessing mass transfer and water management capabilities in MFFs for PEMFC.

The Integrated Preparation of Porous Tungsten Gradient Materials with a Wide Porosity Range

Porous tungsten gradient materials with ordered gradient variations in pore size have significant application value in the field of vacuum electronic devices. This work combines tape casting and dealloying methods to achieve the integrated preparation of porous tungsten gradient materials with a wide range of controllable porosity. The study focused on the phase composition and microstructure evolution during the preparation of porous tungsten gradient materials. The results show that the tape casting process allows for the precise and controllable thickness of each layer of the porous tungsten materials and uniform composition structure, while the stepwise dealloying of Fe and Ti enables a wide range of controllable porosity for the porous tungsten gradient materials. PVB, after thermal decomposition, provides a carbon source for the in situ reaction to form W-Fe-C compounds, and the surface diffusion behavior of W-Fe-C compounds at high temperatures improves the stratification of the porous tungsten gradient materials. This work provides a design concept for the integrated preparation of porous metal gradient materials.

Germ must be found: The HNT@RhB@MOF-Tb polychromatic fluorescent nanoprobe is applied for the visual detection of 2,6-dipicolinic acid

A polychromatic fluorescent nanoprobe based on natural halloysite nanotubes with fluorescent dyes and porous metal–organic frameworks co-loaded on the surface and inner wall of the nanotubes was constructed for the highly sensitive visual identification of the Bacillus anthracis biomarker 2,6-dichlorophenolic acid (DPA). The limit of detection for DPA was 11.27 nM, which is significantly lower than the spore-borne dose for anthrax infection (60 uM). The multi-color fluorescent probe showed potential for rapid, accurate, and highly selective detection of Bacillus anthracis markers in actual samples. Besides, a portable fluorescence detection platform was developed in combination with a smartphone color scanning APP to simplify the detection process and realize real-time semi-quantitative analysis.

An amino acid-functionalized coordination polymer of Cd(II) as a fluorescent probe detecting Cu(II) ion

Cd(II) complex 1, namely {[Cd(HL)]·CH3OH}n was design as a new fluorescence probe for measuring concentration of Cu2+ ion in aqueous solution. Complex 1 is a 3,6-connected double-layered porous metal–organic framework, which was synthesized by optimizing the ratio of Cd(OH)2 and a new ligand 4'-(((1-carboxyethyl)amino)methyl)-[1,1′-biphenyl]-3,5-dicarboxylic acid (H3L) under solvothermal conditions. It not only had good thermal and solvent stabilities, but also displayed a strong solid-state fluorescence centered at 375 nm with a moderate quantum yield of 37.12% under excitation at 275 nm. More importantly, its fluorescence could be obviously quenched by the addition of Cu2+ ion. The fluorescence quenching may be caused by the weak coordination interaction between Cu2+ and the uncoordinated imino N in ligand (HL)2–, as well as the slightly competitive absorption of excitation light by Cu2+. In the low concentration range of Cu2+ ion, the fluorescence quenching efficiency of complex 1 is closely related to the concentration of Cu2+ ion, and the relationship between fluorescence quenching efficiency and the concentration of added Cu2+ ion could be well fitted by Stern-Volmer equation with KSV being 1.589 × 104 M−1 and the detection limit for Cu2+ ion being 5.7 μM. Our case may provide potential applications for the detection of Cu2+ ion in daily domestic water.

Deciphering feedback regulation of prostaglandin F2α in blood stasis syndrome using nitrogen-doped porous transition metal carbides.

Blood stasis syndrome (BSS) has persistent health risks; however, its pathogenesis remains elusive. This obscurity may result in missed opportunities for early intervention, increased susceptibility to chronic diseases, and reduced accuracy and efficacy of treatments. Metabolomics, employing the matrix-assisted laser desorption/ionization (MALDI) strategy, presents distinct advantages in biomarker discovery and unraveling molecular mechanisms. Nonetheless, the challenge is to develop efficient matrices for high-sensitivity and high-throughput analysis of diverse potential biomarkers in complex biosamples. This work utilized nitrogen-doped porous transition metal carbides and nitrides (NP-MXene) as a MALDI matrix to delve into the molecular mechanisms underlying BSS pathogenesis. Structural optimization yielded heightened peak sensitivity (by 1.49-fold) and increased peak numbers (by 1.16-fold) in clinical biosamples. Validation with animal models and clinical serum biosamples revealed significant differences in metabolic fingerprints between BSS and control groups, achieving an overall diagnostic efficacy of 0.905 (95% CI, 0.76-0.979). Prostaglandin F2α was identified as a potential biomarker (diagnostics efficiency of 0.711, specificity = 0.7, sensitivity = 0.6), and pathway enrichment analysis disclosed disruptions in arachidonic acid metabolism in BSS. This innovative approach not only advances comprehension of BSS pathogenesis, but also provides valuable insights for personalized treatment and diagnostic precision.

Porous Tantalum Tibial Metaphyseal Cones in Revision Total Knee Arthroplasty: Excellent 10-Year Survivorship

BackgroundHighly porous metal tibial metaphyseal cones (TMCs) are commonly utilized in revision total knee arthroplasty (TKA) to address bone loss and obtain biologic fixation. Mid-term (5 to 10 year) studies have previously demonstrated excellent survivorship and high rates of osseointegration, but longer-term studies are lacking. We aimed to assess long-term (≥ 10 year) implant survivorship, complications, and clinical and radiographic outcomes after revision TKA with TMCs. MethodsBetween 2004 and 2011, 228 revision TKAs utilizing porous tantalum TMCs with stemmed tibial components were performed at a single institution and were retrospectively reviewed. The mean age at revision was 65 years, the mean body mass index was 33, and 52% were women. Implant survivorship, complications, and clinical and radiographic outcomes were assessed. The mean follow-up was 6.3 years. ResultsThe 10-year survivorship free of aseptic loosening leading to TMC removal was 97%, free of any TMC removal was 88%, free of any re-revision was 66%, and free of any reoperation was 58%. The most common indications for re-revision were periprosthetic joint infection, instability, and aseptic femoral component loosening. The 10-year nonoperative complication rate was 24%. The mean Knee Society scores increased from 38 preoperatively to 69 at 10 years. There were 8 knees that had evidence of partial, progressive tibial radiolucencies at 10 years. ConclusionsPorous tantalum TMCs demonstrated persistently durable longer-term survivorship with a low rate of implant removal. The rare implant removals for component loosening or instability were offset by those required for periprosthetic joint infection, which accounted for 80% of cone removals. Porous tantalum TMCs provide an extremely reliable tool to address tibial bone loss and achieve durable long-term fixation in revision TKA. Level of EvidenceIV.

How modular porous metal augments have changed the management of acetabular bone loss at primary or revision total hip arthroplasty.

The advent of modular porous metal augments has ushered in a new form of treatment for acetabular bone loss. The function of an augment can be seen as reducing the size of a defect or reconstituting the anterosuperior/posteroinferior columns and/or allowing supplementary fixation. Depending on the function of the augment, the surgeon can decide on the sequence of introduction of the hemispherical shell, before or after the augment. Augments should always, however, be used with cement to form a unit with the acetabular component. Given their versatility, augments also allow the use of a hemispherical shell in a position that restores the centre of rotation and biomechanics of the hip. Progressive shedding or the appearance of metal debris is a particular finding with augments and, with other radiological signs of failure, should be recognized on serial radiographs. Mid- to long-term outcomes in studies reporting the use of augments with hemispherical shells in revision total hip arthroplasty have shown rates of survival of > 90%. However, a higher risk of failure has been reported when augments have been used for patients with chronic pelvic discontinuity.

Numerical simulation of heat transfer performance in an enclosure filled with a metal foam and nano-enhanced phase change material

Nowadays phase change materials are widely used in different engineering systems to perform effective cooling techniques for heat-generating elements or to accumulate the thermal energy effectively. The disadvantage of the phase change material is a low thermal conductivity, but it can be improved using porous media or metal nanoadditives of high thermal conductivity. The present research is devoted to the mathematical simulation of conjugate thermal convection in a closed chamber partially filled with metal foam saturated with nano-enhanced phase change material. The governing equations have been formulated using the Oberbeck-Boussinesq equations with the Stefan problem approach for the liquid phase and the heat conduction equation for the solid phase. The finite difference technique in combination with non-primitive variables has been used for numerical analysis. The developed in-house numerical program has been verified using the grid independence test as well as the experimental and theoretical outcomes of other authors. The effects of the metal foam properties and nanoadditives characteristics on melt behavior and thermal energy transport parameters have been studied. The main attention is paid to the influence of a filling height ratio of the metal foam on the heat transport process. It has been revealed that the impact of the metal foam on thermal dissipation is essentially higher compared to the nanoadditives influence. Therefore, in the case of full height foam, the effect of nanoparticles is weak, but in the cavity with a partial height of the porous medium, NePCM can be melted faster than pure PCM and has a negative effect on the heater temperature. It has been also found that changing the filling height ratio from 0.167 to 0.5 does not lead to a significant change in the temperature of the heater.

Traveling wave vibration and critical rotating speed of rotating porous metal conical shell with elastic boundary conditions

This article examines the traveling wave vibration modes of rotating porous metal conical shell (PMCS) by exploiting the differential quadrature method (DQM). A series of artificial springs are introduced to the system to simulate arbitrary elastic support boundary conditions. Making use of the generalization virtual displacements principle and the first-order shear deformation theory (FSDT) of laminate plate, the theoretical formula is derived, in which both the Coriolis force and the initial circumferential tension brought on by the rotation of the conical shell are included. The trigonometric function is used to indicate the circumferential mode shapes, while the DQM is adopted in generatrix direction to acquire the unified solution. By comparing the present research results and those of the previous researches, the reliability and convergence of the present formulation and numerical simulation are confirmed. Considering three different porosity distributions of the PMCS, the effects of porosity distribution, geometrics, spinning speed, boundary constraint types and the circumferential wave number on frequencies and mode shapes of traveling wave vibration of the PMCS are investigated in detail. Furthermore, the critical rotating speed (CRS) and resonance angular speed are discussed for the rotating PMCS.