Comparison of Foaming Properties Between the Shirasu Porous Glass Membrane Device and Tessari’s Three-way Stopcock Technique for Polidocanol and Ethanolamine Oleate Foam Production: A Benchtop Study

PurposeTo compare the characteristics of polidocanol (POL) and ethanolamine oleate (EO) sclerosing foams produced by a Shirasu porous glass membrane (SPGM) device with those made using a 3-way stopcock (3WSC).Materials and MethodsFoam half-life times were measured in an ex-vivo benchtop study. Computed tomography (CT) images of each foam were obtained over the time course, and a CT texture analysis was conducted. The bubble size in each foam was measured by an optical microscope.ResultsMedian foam half-life times were longer in the SPGM group than in the 3WSC group (POL: 198 vs 166 s, P = .02; EO: 640 vs 391 s, P < .01). In the CT texture analysis, median standard deviation (SD) and entropy (randomness) were lower, and median energy (uniformity) and gray-level cooccurrence matrix (GLCM) homogeneity were higher in the SPGM group than in the 3WSC group (POL SD: at 30 s and 50–300 s; POL entropy: at 0–60 s; EO SD: at 0–600 s; EO entropy: at 0–460 s; POL energy: at 0–40 s; POL GLCM homogeneity: at 0–250 s; EO energy: at 0–360 s; EO GLCM homogeneity: at 0–480 s; all P < .05). Median bubble diameters in the SPGM group and in the 3WSC group were 69 and 83 μm (P < .01), respectively, in the POL foam; and 36 and 36 μm (P = .45), respectively, in the EO foam.ConclusionsPOL and EO foams had greater uniformity and longer foam half-life time when prepared with an SPGM device than with a 3WSC.     

Biocompatible Porous Tantalum Metal Plates in the Treatment of Tibial Fracture

Fractures of the tibia represent a common class of injuries in orthopedics. The blood supply to the tibia is poor due to the small subcutaneous muscle tissues inside. Consequently, the tibia is prone to delayed fracture healing and nonunion of the fracture after surgery. In this case, we used porous tantalum metal plate to treat nonunion of a tibial fracture and achieved satisfactory therapeutic effects. For the first time in the field, we used 3D printing technology to fabricate porous tantalum metal plates for the treatment of tibial fractures. The resulting porous tantalum metal exhibited excellent mechanical and biological properties, and improved the therapeutic effects for the treatment of a tibial fracture nonunion. Porous tantalum metal plates have great application potential as a new implant material for internal fixation.     

Contemporary bone loss options: Rebuild,reinforce, and augment

Bone loss is commonly encountered during revision total knee arthroplasty (TKA). Small defects can be adequately managed with cement filling (with or without screws), modular prosthetic augments, and morselized allograft. For larger defects, cancellous impaction grafting and structural allografts have traditionally been utilized. More recently, highly porous tantalum cones and titanium sleeves have been designed to achieve axial and rotational stability in the metaphysis and subsequent biologic fixation. Sleeves are linked to one type of prosthesis, whereas cones are unlinked and can be used with any implant design. Multiple studies have demonstrated excellent survivorship and radiographic osseointegration at mid-term follow-up. This article provides a review of contemporary methods of bone loss management with a focus on highly porous metals and an emphasis on the authors’ preferred method for managing the severe bone loss in revision TKA.     

A Computational Geometry Generation Method for Creating 3D Printed Composites and Porous Structures

A computational method for generating porous materials and composite structures was developed and implemented. The method is based on using 3D Voronoi cells to partition a defined space into segments. The topology of the segments can be controlled by controlling the Voronoi cell set. The geometries can be realized by additive manufacturing methods, and materials can be assigned to each segment. The geometries are generated and processed virtually. The macroscopic mechanical properties of the resulting structures can be tuned by controlling microstructural features. The method is implemented in generating porous and composite structures using polymer filaments i.e., polylactic acid (PLA), thermoplastic polyurethane (TPU) and nylon. The geometries are realized using commercially available double nozzle fusion deposition modelling (FDM) equipment. The compressive properties of the generated porous and composite configurations are tested quasi statically. The structures are either porous of a single material or composites of two materials that are geometrically intertwined. The method is used to produce and explore promising material combinations that could otherwise be difficult to mix. It is potentially applicable with a variety of additive manufacturing methods, size scales, and materials for a range of potential applications.     

Hazardous Petroleum Sludge-Derived Nitrogen and Oxygen Co-Doped Carbon Material with Hierarchical Porous Structure for High-Performance All-Solid-State Supercapacitors

Rational design and sustainable preparation of high-performance carbonaceous electrode materials are important to the practical application of supercapacitors. In this work, a cost-effective synthesis strategy for nitrogen and oxygen co-doped porous carbon (NOC) from petroleum sludge waste was developed. The hierarchical porous structure and ultra-high surface area (2514.7 m² g⁻¹) of NOC electrode materials could provide an efficient transport path and capacitance active site for electrolyte ions. The uniform co-doping of N and O heteroatoms brought enhanced wettability, electrical conductivity and probably additional pseudo-capacitance. The as-obtained NOC electrodes exhibited a high specific capacitance (441.2 F g⁻¹ at 0.5 A g⁻¹), outstanding rate capability, and cycling performance with inconspicuous capacitance loss after 10,000 cycles. Further, the assembled all-solid-state MnO₂/NOC asymmetrical supercapacitor device (ASC) could deliver an excellent capacitance of 119.3 F g⁻¹ at 0.2 A g⁻¹ under a wide potential operation window of 0–1.8 V with flexible mechanical stability. This ASC device yielded a superior energy density of 53.7 W h kg⁻¹ at a power density of 180 W kg⁻¹ and a reasonable cycling life. Overall, this sustainable, low-cost and waste-derived porous carbon electrode material might be widely used in the field of energy storage, now and into the foreseeable future.     

Droplet fragmentation: 3D imaging of a previously unidentified pore-scale process during multiphase flow in porous media

Using X-ray computed microtomography, we have visualized and quantified the in situ structure of a trapped nonwetting phase (oil) in a highly heterogeneous carbonate rock after injecting a wetting phase (brine) at low and high capillary numbers. We imaged the process of capillary desaturation in 3D and demonstrated its impacts on the trapped nonwetting phase cluster size distribution. We have identified a previously unidentified pore-scale event during capillary desaturation. This pore-scale event, described as droplet fragmentation of the nonwetting phase, occurs in larger pores. It increases volumetric production of the nonwetting phase after capillary trapping and enlarges the fluid−fluid interface, which can enhance mass transfer between the phases. Droplet fragmentation therefore has implications for a range of multiphase flow processes in natural and engineered porous media with complex heterogeneous pore spaces.Multiphase fluid displacement processes in porous media are important for a broad range of natural and engineering applications such as transport of nonaqueous phase liquid contaminants in aquifers, oil and gas production from hydrocarbon reservoirs, subsurface CO₂ storage, or gas transport in fuel cells. Herein, capillary trapping is a fundamental mechanism that causes immobilization of a portion of the resident nonwetting phase when it is displaced by an invading wetting phase. As a result, production of the nonwetting phase is always less than 100%.The pore-scale physics of capillary trapping are broadly understood, as the underlying mechanisms such as piston-like displacement, snap-off and film development have been observed in physical micromodel experiments and quantitative theories have been established for them (1–4). The conventional view considers such pore-scale processes to occur between multiple pores, i.e., they are interpore processes and the pores are defined as volumes connected by narrower pore throats. By contrast, intrapore processes, as presented in this paper, are not well established in the literature. During drainage (i.e., where a nonwetting phase displaces the wetting phase), the wetting phase can establish films in the corners of the pores, which results in its continuous production and hence low residual saturations of the wetting phase. During imbibition (i.e., where the wetting phase displaces a nonwetting phase), swelling of the corner wetting films causes snap-off of the nonwetting phase, which results in capillary trapping of the nonwetting phase. The trapped nonwetting phase exists as disconnected ganglia within the pore network. Numerical pore network models have been developed to include these pore-level mechanisms with the aim of predicting the macroscopic flow properties of porous materials such as the structure of the phase distributions, residual saturation, relative permeability functions, and capillary pressure curves. Some of these models, referred to as quasi-static models, assume that fluid flow is only governed by capillary forces (5–8), and hence are limited in capturing the dynamics of fluid displacements that occur under the action of both capillary and viscous forces. In another class of pore network models, referred to as dynamic models (9–11), capillary and viscous forces are considered simultaneously. Such models are more applicable in modeling the dynamics of pore-scale events controlled by both capillary and viscous forces.The saturation distribution of two immiscible fluid phases in a porous medium is influenced by the wettability of the system, i.e., the distribution of surfaces that are preferentially water wet or preferentially wetting to a nonaqueous phase such as oil (12). It is known that a trapped nonwetting phase can be remobilized and recovered when the wetting phase is injected at capillary numbers N_c that exceed a critical level. N_c is a dimensionless ratio quantifying the relative importance of viscous to capillary forces, i.e., N_c = vµ/σ where v is the apparent velocity, µ is the viscosity of the invading phase, and σ is the interfacial tension (13). For homogeneous sandstones, remobilization typically occurs at N_c of the order of 10⁻⁵, an effect known as capillary desaturation (14).Recent advances in X-ray computed microtomography (µCT) methods have enabled the visualization and quantitative analysis of the static distribution of fluid phases, fluid rock interactions, and the structure of wetting and nonwetting phases in porous materials (8, 15). A particular focus has been on capillary trapping (16–20). Using synchrotron X-ray μCT facilities, it has also become possible to visualize dynamic pore-scale mechanisms, including snap-off and Haines jumps (21). Most of these imaging studies have focused on relatively homogeneous pore systems such as bead packs (22), sand packs (22–26), and sandstones (8, 18, 21, 23), but less attention has been paid to carbonate rocks. However, more than 50% of the world’s remaining oil reserves are located in carbonate reservoirs (27), and carbonate aquifers supply water wholly or partially to one quarter of the global population (28). Carbonates rocks can have complex multiscale pore structures, which render the application of X-ray µCT more challenging because of the need to select a representative sample that is small enough to achieve high resolutions on µCT images but that also captures the essential heterogeneities of the pore structure (29, 30).In this contribution, we use X-ray µCT to quantify the structure and distribution of a nonwetting phase (oil) after drainage and after its displacement by a wetting phase (brine) at low and high capillary numbers in a heterogeneous carbonate with multiple pore scales. Using image analysis, we demonstrate the effect of capillary desaturation on the cluster size distribution of the trapped oil phase. We identify a previously unidentified pore-scale event, which we refer to as droplet fragmentation. Droplet fragmentation is responsible for further production of the oil phase beyond capillary trapping. This fragmentation process occurs mainly in larger pores. It results in the production of additional oil from these large pores, contributes to a change in the structure of residual oil, and increases the oil−brine surface area. As a consequence, the trapped phase may subsequently be more difficult to mobilize after droplet fragmentation has occurred but mass transfer between the phases can increase.     

Corrosion resistance and biocompatibility of a new porous surface for titanium implants

Alterations of the commercially pure titanium (cpTi) surface may be undertaken to improve its biological properties. The aim of this study was to investigate the biocompatibility of cpTi when submitted to a new, porous titanium, surface treatment (porous Ti). Five types of surface treatments, namely sintered microspheres porous titanium (porous Ti), titanium plasma spray (TPS), hydroxyapatite (HA), sandblasted and acid etched (SBAE), and resorbable blast medium, sandblasted with hydroxyapatite (RBM) were made. In the experimental methods, the corrosion potentials were measured over time, and then a linear sweep voltammetric analysis measured the polarization resistances and corrosion currents. For biocompatibility evaluation, MG63 osteoblast-like cells were used. Cell morphology, cell proliferation, total protein content, and alkaline phosphatase (ALP) activity were evaluated after 2 h, and after 2, 4 and 7 d. Porous Ti and SBAE showed a better corrosion resistance, with a weak corrosion current and a high polarization resistance, than the other surfaces. Cell attachment, cell morphology, cell proliferation, and ALP synthesis were influenced by the surface treatments, with a significant increase observed of the activity of osteoblast cells on the porous coating (porous Ti). Based on these results, it is suggested that the porous Ti surface has a significantly better biocompatibility than the other surface treatments and an excellent electrochemical performance.     

Effective Enzyme Coimmobilization and Synergistic Catalysis on Hierarchically Porous Inorganic/Organic Hybrid Microbeads Fabricated Via Droplet‐Based Microfluidics

In this paper, a novel and robust droplet‐based microfluidic method to fabricate poly(ε‐caprolactone)/silica (PCL/SiO₂) hybrid microbeads with hierarchically porous architecture is described and their performance as multienzyme carriers for cascade catalysis is further investigated in detail. In addition to the precise control on size and monodispersity of PCL/SiO₂ microbeads enabled by the microfluidic method, the presence of ammonia as a catalyst for the hydrolysis and condensation of tetraethylorthosilicate makes it possible to manipulate the competition between sol–gel process and solvent extraction and thus adjust the surface porosity of hybrid microbeads, which eliminates the use of porogens/templates and also the complicated post‐treatment. Isothiocyanate‐immunoglobulin G/cyanine 3‐bovine serum albumin (FITC‐IgG/Cy3‐BSA) and superoxide dismutase/chloramphenicol acetyltransferase (SOD/CAT) are coimmobilized, respectively onto hierarchically porous PCL/SiO₂ hybrid microbeads via either physical adsorption or covalent binding. Fluorescence intensity of coimmobilized FITC‐IgG/Cy3‐BSA proves that the proteins/enzymes immobilization amount via covalent binding is much higher than physical adsorption. The enhanced enzymatic activity, total antioxidant capacity, and reusability assay reveal that coimmobilized SOD/CAT exhibits better performance compared with the mono‐immobilized ones, mainly due to their mutual synergistic effect. The excellent results achieved in the work indicate that hierarchically porous PCL/SiO₂ hybrid microbeads are very promising carriers for multienzymatic catalysis.     

中空多孔钛假体复合松质骨基质兔体内骨生成组织学研究

目的：利用复合松质骨基质(Cancellous bone matrix ,CBM)的中空多孔钛假体(Hollow porous titanium prostheses, HPTP)观察兔体内假体周围及内部骨生成情况,探讨人工假体与骨质整合的改进方法。方法设计中空多孔(孔径2 mm)和无孔两种假体,表面行羟基磷灰石(Hydroxyapatite ,HA)喷涂。实验组分为无孔假体组(A组)、HPTP组(B组)和HPTP＋CBM组(C组),每组16例。将假体分别植入48只4~6个月龄新西兰大白兔右侧股骨外侧髁,饲养至第3、8、12周时取材,以X线、显微镜、电镜及形态计量软件观察复合假体表面及内部骨生成情况。采用SPSS13.0进行t检验分析。结果三组植入物外表面HA涂层的组织生长情况类似;A组无孔,未见骨长入,B组和C组中骨组织最终可长入假体2 mm大的圆孔;各时间点C组中空腔内骨生长率均明显高于B组(P<0.01)。结论骨质可经HPTP假体孔洞长入腔内,达到交锁固定,较无孔假体更稳定;中空腔复合CBM后可明显加快骨长入并诱导骨生成,使假体与骨质更好整合。