Μm Average Pore Size Research Articles

Oxidation of Ammonia in Water Microdroplets Produces Nitrate and Molecular Hydrogen.

Water microdroplets containing dissolved ammonia (30-300 μM) are sprayed through a copper oxide mesh with a 200 μm average pore size, resulting in the formation of nitrate (NO3-) and the release of molecular hydrogen (H2). The products result from a redox process that takes place at the liquid-solid interface through contact electrification, where no external potential is applied. Oxidation is initiated by superoxide radical anions (O2-) that originate from the oxygen in the air surrounding the microdroplets and from the hydroxyl radicals (OH•) originating from the water-air interface. Two spin traps (TEMPO and DMPO) capture these radicals as well as NH2OH+•, HNO, NO•, NO2•, and NOOH, which are detected by mass spectrometry. We also directly observed N2O2-• by the same means. We found that the hydrogen atom from the ammonia molecule can be set free not only in the form of H• but also as H2, which is detected using a residue gas analyzer. The oxidation process can be significantly enhanced by a factor of 3 when the sprayed microdroplets are irradiated with ultraviolet light (265 nm, 5 W). 35% of 300 μM ammonia can be degraded within 20 μs, and the nitrate conversion rate is estimated to be 15 nmol·mg-1·h-1.

Treatment of food processing industries wastewater using a novel Fuller's earth clay-based tubular ceramic membrane.

This study investigates the feasibility of a robust, low-cost tubular microfiltration ceramic membrane fabricated using a mixture of locally available Fuller's earth clay (FEC) and solid waste material, rice husk ash (RHA), to treat effluents generated by a local dairy and palm oil industries. Fabrication of the membrane was carried out by employing the extrusion method followed by sintering at a temperature of 850 °C. Raw materials were characterized using XRD, XRF, FTIR, TGA, and differential thermal analysis (DTA). The membrane that underwent sintering exhibits a 61% porosity level, 43.29 L/m2 h bar water permeability, 0.115 μm average pore size, and relatively good corrosion resistance. Further, the effect of different operating conditions, including pressure (1.03-2.41 bar) and cross-flow rate (30-150 Lph), on the microfiltration of both the wastewaters is studied. The membrane lowered the COD levels below the discharge limit (<200 mg/L) of the Central Pollution Control of India for both wastewaters. Finally, Hermia's fouling models were used to identify the fouling mechanism concerned.

Facile preparation of diblock copolymers as functional surfaces for protein chromatography

AbstractStationary phase plays a crucial role in the operation of a protein chromatography column. Conventional resins composed of acrylic polymers and their derivatives contribute to heterogeneity of the packing of stationary phase inside these columns. Alternative polymer combinations through customized surface functionalization schemes which consist of multiple steps using static coating techniques are well known. In comparison, it is hypothesized that single‐step scheme is sufficient to obtain porous adsorbents as stationary phase for tuning surface morphology and protein immobilization. To overcome the challenge of heterogeneous packing and ease of fabrication at laboratory scale, change in the form factor of separation materials has been proposed in the form of functional copolymer surfaces. In the present work, an amphiphilic, block copolymer, poly(methyl methacrylate‐co‐methacrylic acid) has been chosen and fully characterized for its potential usage in protein chromatography. Hydrophilicity of the acrylic copolymer and abundance of carboxyl groups inherently on the copolymer surface have been successfully demonstrated through contact angle measurements, Fourier transform infrared (FTIR) and X‐ray photoelectron spectroscopy (XPS) studies. Morphological studies indicate presence of a microporous region (nearly 1.3 μm average pore size) that could be beneficial as a cation exchange media as part of the stationary phase in protein chromatography.

Versatile Biodegradable Poly(acrylic acid)-Based Hydrogels Infiltrated in Porous Titanium Implants to Improve the Biofunctional Performance.

This research work proposes a synergistic approach to improve implants' performance through the use of porous Ti substrates to reduce the mismatch between Young's modulus of Ti (around 110 GPa) and the cortical bone (20-25 GPa), and the application of a biodegradable, acrylic acid-based polymeric coating to reduce bacterial adhesion and proliferation, and to enhance osseointegration. First, porous commercially pure Ti substrates with different porosities and pore size distributions were fabricated by using space-holder techniques to obtain substrates with improved tribomechanical behavior. On the other hand, a new diacrylate cross-linker containing a reduction-sensitive disulfide bond was synthesized to prepare biodegradable poly(acrylic acid)-based hydrogels with 1, 2, and 4% cross-linker. Finally, after the required characterization, both strategies were implemented, and the combination of 4% cross-linked poly(acrylic acid)-based hydrogel infiltrated in 30 vol % porosity, 100-200 μm average pore size, was revealed as an outstanding choice for enhancing implant performance.

Antibacterial, Anti-Biofilm and Pro-Migratory Effects of Double Layered Hydrogels Packaged with Lactoferrin-DsiRNA-Silver Nanoparticles for Chronic Wound Therapy.

Antimicrobial resistance and biofilm formation in diabetic foot infections worsened during the COVID-19 pandemic, resulting in more severe infections and increased amputations. Therefore, this study aimed to develop a dressing that could effectively aid in the wound healing process and prevent bacterial infections by exerting both antibacterial and anti-biofilm effects. Silver nanoparticles (AgNPs) and lactoferrin (LTF) have been investigated as alternative antimicrobial and anti-biofilm agents, respectively, while dicer-substrate short interfering RNA (DsiRNA) has also been studied for its wound healing effect in diabetic wounds. In this study, AgNPs were complexed with LTF and DsiRNA via simple complexation before packaging in gelatin hydrogels. The formed hydrogels exhibited 1668% maximum swellability, with a 46.67 ± 10.33 µm average pore size. The hydrogels demonstrated positive antibacterial and anti-biofilm effects toward the selected Gram-positive and Gram-negative bacteria. The hydrogel containing AgLTF at 125 µg/mL was also non-cytotoxic on HaCaT cells for up to 72 h of incubation. The hydrogels containing DsiRNA and LTF demonstrated superior pro-migratory effects compared to the control group. In conclusion, the AgLTF-DsiRNA-loaded hydrogel possessed antibacterial, anti-biofilm, and pro-migratory activities. These findings provide a further understanding and knowledge on forming multipronged AgNPs consisting of DsiRNA and LTF for chronic wound therapy.

Surgical cotton microfibers loaded with proteins and apatite: A potential platform for bone tissue engineering

Tissue engineering has emerged as the best alternative to replacing damaged tissue/organs. However, the cost of scaffold materials continues to be a significant obstacle; thus, developing inexpensive scaffolds is strongly encouraged. In this study, cellulose microfibers (C), gelatin (G), egg white (EW), and nanohydroxyapatite (nHA) were assembled into a quaternary scaffold using EDC-NHS crosslinking, followed by freeze-drying method. Cellulose microfibers as a scaffold have only received a limited amount of research due to the absence of an intrinsic three-dimensional structure. Gelatin, more likely to interact chemically with collagen, was used to provide a stable structure to the cellulose microfibers. EW was supposed to provide the scaffold with numerous cell attachment sites. nHA was chosen to enhance the scaffold's bone-bonding properties. Physico-chemical, mechanical, and biological characterization of scaffolds were studied. In-vitro using MG-63 cells and in-ovo studies revealed that all scaffolds were biocompatible. The results of the DPPH assay demonstrate the ability of CGEWnHA to reduce free radicals. The CGEWnHA scaffold exhibits the best properties with 56.84 ± 28.45 μm average pore size, 75 ± 1.4 % porosity, 39.23 % weight loss, 109.19 ± 0.98 kPa compressive modulus, and 1.72 Ca/P ratio. As a result, the constructed CGEWnHA scaffold appears to be a viable choice for BTE applications.

Investigation of membrane wetting for CO2 capture by gas–liquid contactor based on ceramic membrane

In recent years, global climate change caused by excessive CO2 emissions has attracted wide attention. Within this context, CO2 capture by gas–liquid contactor based on membranes is one of the most promising technologies for post-combustion CO2 capture. However, mass transfer deterioration due to membrane wetting becomes one of barriers for its development. In this paper, based on Laplace-Young equation, reliable individual membrane pore wetting model is constructed to demonstrate detailed wetting process inside membrane pores, which is verified by molecular dynamic (MD) numerical simulation. The wetting conditions of ceramic membrane with 1.26 µm average pore size and 51.4° contact angle are investigated in experiments. The results show that neither average nor maximum pore diameters can accurately predict liquid and bubble breakthrough pressures of ceramic membrane. The actual liquid and bubble breakthrough pressures of ceramic membrane are slightly lower than critical liquid and bubble breakthrough pressures corresponding to the maximum pore size. The wetting state of ceramic membrane can be determined by combining individual pore wetting model and actual membrane pore distribution. In addition, for practical application process of CO2 capture by gas–liquid contactor with ceramic membrane, some suggestions to avoid membrane wetting are proposed for selection of ceramic membrane and system operation perspective. The membrane wetting analysis method proposed in this paper not only contributes to future applications of ceramic membrane in CO2 capture, but is also widely applicable to other gas–liquid contactors in membrane separation process.

Flexible Carbon Sponge Electrodes for All Vanadium Redox Flow Batteries.

In the present work, a flexible carbon sponge is experimentally characterized and proposed as an alternative electrode for advanced vanadium redox flow batteries. Such an electrode is prepared via directly carbonizing the commercially-available and inexpensive melamine formaldehyde resin sponge in argon, to inherit the well-defined and three-dimensional bi-continuous architecture of the melamine sponge with 99.6% porosity and 40 μm average pore size. By applying the carbon sponges as the electrodes, it is demonstrated that the vanadium flow battery at 200 mA cm-2 can yield an energy efficiency of 77.9%, significantly higher than that with commonly-used graphite felt electrodes (72.9%). After a thermal treatment in air, the energy efficiency of carbon sponge can further be improved to 81.2% at mA cm-2 due to introduction of favorable oxygen containing functionalities. The operating stability with the carbon sponge is proven by a 200 cycling test with minor efficiency decay.

Experimental Evaluation of Performance Characteristics of a Horizontal Copper Mesh Wick-Based Miniature Loop Heat Pipe

The ever-increasing computational power of the electronic devices accompanies a greater power dissipation. Understanding and optimization of the heat rejection systems are thus vital to ensure effective thermal management of electronic devices in an often highly confined space. This paper reports the design, development, and results of an experimental investigation of a fast responding and passive heat-rejecting copper–water-based miniature loop heat pipe (mLHP) system. The designed mLHP has a square flat-faced evaporator of 20 mm length with opposite replenishment, four extended surfaces with vapor space, a liquid reservoir or compensation chamber, fin- and tube-type condenser, and different diameter transport lines. Capillary pumping action was ensured by a composite of 100PPI copper mesh with 37% porosity and absorbent wool of 20 µm average pore size. Wick hydration was safeguarded by a 67% filling ratio of mLHP at a cold state. A decrease in thermal resistance and an increase in heat transfer coefficient for evaporation were observed. The thermal resistance of the evaporator and mLHP was 0.109–0.396 °C/W and 0.132–0.644 °C/W with an uncertainty of 3.749% and 3.744%, respectively. The heat transfer coefficient for evaporation achieved during experimentation was 6.313–23.00 kW/m2K with 0.345% uncertainty. No reverse flow of vapors and evaporator dry-out was detected. The maximum temperature sustained was 108 °C against the 205 W heat load with a 4.5-min start-up duration. These results reveal the suitability of the designed miniature loop heat pipe for the heat dissipation of electronics.

Vaterite submicron particles designed for photodynamic therapy in cells.

Calcium carbonate (CaCO3) is one of the most abundant materials in the world. It has several different crystalline phases as present in the minerals: calcite, aragonite and vaterite, which are anhydrous crystalline polymorphs. Regarding the preparation of these microparticles, the most important aspect is the control of the polymorphism, particle size and material morphology. This study aimed to develop porous microparticles of calcium carbonate in the vaterite phase for the encapsulation of chloro-aluminum phthalocyanine (ClAlPc) as a photosensitizer (PS) for application in Photodynamic Therapy (TFD). In this study, spherical vaterite composed of microparticles are synthesized by precipitation route assisted by polycarboxylate superplasticizer (PSS). The calcium carbonate was prepared by reacting a mixed solution of Na2CO3 with a CaCl2 solution at an ambient temperature, 25 °C, in the presence of polycarboxylate superplasticizer as a stabilizer. The photosensitizer was incorporated by adsorption technique in the CaCO3 microparticles. The CaCO3 microparticles were studied by scanning electron microscopy, steady-state, and their biological activity was evaluated using in vitro cancer cell lines by trypan blue exclusion method. The intracellular localization of ClAlPc was examined by confocal microscopy. The CaCO3 microparticles obtained are uniform and homogeneously sized, non-aggregated, and highly porous microparticles. The calcium carbonate microparticles show an average size of 3 μm average pore size of about 30-40 nm. The phthalocyanine derivative loaded-microparticles maintained their photophysical behavior after encapsulation. The captured carriers have provided dye localization inside cells. The in vitro experiments with ClAlPc-loaded CaCO3 microparticles showed that the system is not cytotoxic in darkness, but exhibits a substantial phototoxicity at 3 μmol.L-1 of photosensitizer concentration and 10 J.cm-2 of light. These conditions are sufficient to kill about 80 % of the cells. All the performed physical-chemical, photophysical, and photobiological measurements indicated that the phthalocyanine-loaded CaCO3 microparticles are a promising drug delivery system for photodynamic therapy and photoprocesses.

Controllable fabrication of hydroxybutyl chitosan/oxidized chondroitin sulfate hydrogels by 3D bioprinting technique for cartilage tissue engineering

Biological regeneration of articular cartilage continues to be a challenge at present. Functional engineered implants with patient-specific sizes are difficult to achieve. The aim of this study is to fabricate a biocompatible cell-laden hydrogel with a designable structure. Covalent hydrogels were prepared with water soluble hydroxybutyl chitosan (HBC) and oxidized chondroitin sulfate (OCS) via a Schiff-base reaction. With the aid of three-dimensional (3D) bioprinted sacrificial molds, HBC/OCS hydrogel with various structures were obtained. After the material constituent optimization process, an injectable hydrogel with a uniform porous structure of 100 μm average pore size was developed to form macroporous hydrogel. In vitro and in vivo biocompatibility of optimized HBC/OCS hydrogel were also carefully assessed. The results indicated that human adipose-derived mesenchymal stem cells could be 3D cultured in HBC/OCS hydrogel maintaining good viability. Moreover, the hydrogels were found to trigger the least amount of pro-inflammatory gene expression of macrophage and to inhibit acute immune responses in 7 d. These results demonstrate the potential of HBC/OCS hydrogels as a cell delivery system for cartilage tissue engineering.

Preparation of a modified crosslinked chitosan/polyvinyl alcohol blended affinity membrane for purification of His‐tagged protein

ABSTRACTBased on a crosslinked chitosan (CS)/polyvinyl alcohol (PVA) matrix membrane, an immobilized metal ion affinity membrane (IMAM) using Cu2+ and Ni2+ ions as affinity ligands was prepared for purification of the His‐tagged recombinant protein. The affinity membrane possessed a favorable membrane structure including 1.39 μm average pore size and 0.33 mL·cm−2·s−1 water flux under 0.08 MPa pressure at 25 °C. The Cu2+ and Ni2+ ions capacities immobilized on the IMAM were 155.6 and 137.3 μmol·disk−1, respectively. The IMAM had an excellent specific affinity to His‐tagged protein. About 10‐fold purification factor for the model protein was obtained in a batch adsorption, and serine hydroxymethyl transferase could be purified to a single band in sodium dodecyl sulfate–polyacrylamide gel electrophoresis analysis from its crude extract solution with an affinity membrane cartridge by a dynamic purification process. This work provides a promising IMAM for the purification of His‐tagged recombinant proteins. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47347.

Tungsten Matrix Material for Diffusion Barium Tungsten Cathode

As the core component of the diffusion cathode, the performance of porous tungsten matrix material will directly affect the output performance and life of microwave source. Therefore, the preparation of porous tungsten matrix is the key process of making a cathode material. In this paper, the industrial tungsten powder was used as raw material, whose particle size was modulated by fluidic classification firstly. Then via cold isostatic pressing and hydrogen sintering in high temperature, the porous tungsten sintered body was obtained. Finally, by the process of copper infiltration, machining and copper removal, the porous tungsten matrix was achieved. The result showed that compared with raw material tungsten powder, the classified tungsten powder’s particle size distribution was narrowed and its tap density obviously increased, indicating that it had better particle stacking performance. Setting the temperature between 1900°C and 2050°C the high temperature hydrogen sintering experiment was conducted, and it was found that the volume shrinkage ratio of tungsten sintered body increased with the sintering temperature, and correspondingly, its total porosity decreased from 24.4% at 1900°C to 20.8% at 2050°C. It was characterized by MIP (mercury intrusion porosimetry) that at high temperature between 1950~2050°C, the porous tungsten matrix with an open porosity of 21±1%, 1.30~1.60μm average pore size, a close cell ratio less than 1% and the skeleton strength greater than 150MPa was obtained. Thus this porous tungsten matrix is an ideal material to be applied to highly reliable diffusion bariated tungsten cathode manufacturing.

Influence of Porosity and Pore-Size Distribution in Ti6Al4 V Foam on Physicomechanical Properties, Osteogenesis, and Quantitative Validation of Bone Ingrowth by Micro-Computed Tomography.

Cementless fixation for orthopedic implants aims to obviate challenges associated with bone cement, providing long-term stability of bone prostheses after implantation. The application of porous titanium and its alloy-based implants is emerging for load-bearing applications due to their high specific strength, low stiffness, corrosion resistance, and superior osteoconductivity. In this study, coagulant-assisted foaming was utilized for the fabrication of porous Ti6Al4 V using egg-white foam. Samples with three different porosities of 68.3%, 75.4%, and 83.1% and average pore sizes of 92, 178, and 297 μm, respectively, were prepared and subsequently characterized for mechanical properties, osteogenesis, and tissue ingrowth. A microstructure-mechanical properties relationship study revealed that an increase of porosity from 68.3 to 83.1% increased the average pore size from 92 to 297 μm with the subsequent reduction of compresive strength by 85% and modulus by 90%. Samples with 75.4% porosity and a 178 μm average pore size produced signifcant osteogenic effects on human mesenchymal stem cells, which was further supported by immunocytochemistry and real-time polymerase chain reaction data. Quantitative assessment of bone ingrowth by micro-computed tomography revealed that there was an approximately 52% higher bone formation and more than 90% higher bone penetration at the center of femoral defects in rabbit when implanted with Ti6Al4 V foam (75.4% porosity) compared to the empty defects after 12 weeks. Hematoxylin and eosin (H&E) and Masson trichrome (MT) staining along with energy-dispersive X-ray mapping on the sections obtained from the retrieved bone samples support bone ingrowth into the implanted region.

Polyurethane–Ceramic matrices as orbital implants

ABSTRACTOrbital implants are used in such procedures as a method by which the natural void created by the removal of an eye can be filled to restore structural and mechanical stability in the region. Highly biocompatible, easy-to-process, relatively inexpensive, chemically and structurally nonabrasive material with high functionality is yet to be proposed for this application. This study investigates a new semibiodegradable, porous polyurethane/beta-tricalcium phosphate composite as a potential material for orbital implant construction. The orbital implant material presented is composed of polyurethane and ceramic components. Isocyanate, caprolactone monomers, catalyst, and deionized water were used for the preparation of polyurethane. The porosity is observed 96.93% with a 267 ± 25 µm average pore size. Young’s Modulus was around 50 MPa. Composite implants showed no cytotoxic, apoptotic, and necrotic effects. This matrix, with a biocompatible, porous, and light-weight structure, and with both suitability for tissue infiltration and incorporation potential, holds great promise.

Microporous Polyurethane Thin Layer as a Promising Scaffold for Tissue Engineering.

The literature describes that the most efficient cell penetration takes place at 200–500 µm depth of the scaffold. Many different scaffold fabrication techniques were described to reach these guidelines. One such technique is solvent casting particulate leaching (SC/PL). The main advantage of this technique is its simplicity and cost efficiency, while its main disadvantage is the scaffold thickness, which is usually not less than 3000 µm. Thus, the scaffold thickness is usually far from the requirements for functional tissue reconstruction. In this paper, we report a successful fabrication of the microporous polyurethane thin layer (MPTL) of 1 mm thick, which was produced using SC/PL technique combined with phase separation (PS). The obtained MPTL was highly porous (82%), had pore size in the range of 65–426 µm and scaffold average pore size was equal to 154 ± 3 µm. Thus, it can be considered a suitable scaffold for tissue engineering purpose, according to the morphology criterion. Polyurethane (PUR) processing into MPTL scaffold caused significant decrease of contact angle from 78 ± 4° to 56 ± 6° and obtained MPTL had suitable hydrophilic characteristic for mammalian cells growth and tissue regeneration. Mechanical properties of MPTL were comparable to the properties of native tissues. As evidenced by biotechnological examination the MPTL were highly biocompatible with no observed apparent toxicity on mouse embryonic NIH 3T3 fibroblast cells. Performed studies indicated that obtained MPTL may be suitable scaffold candidate for soft TE purposes such as blood vessels.

Cationic osteogenic peptide P15-CSP coatings promote 3-D osteogenesis in poly(epsilon-caprolactone) scaffolds of distinct pore size.

P15-CSP is a biomimetic cationic fusion peptide that stimulates osteogenesis and inhibits bacterial biofilm formation when coated on 2-D surfaces. This study tested the hypothesis that P15-CSP coatings enhance 3-D osteogenesis in a porous but otherwise hydrophobic poly-(ɛ-caprolactone) (PCL) scaffold. Scaffolds of 84 µm and 141 µm average pore size were coated or not with Layer-by-Layer polyelectrolytes followed by P15-CSP, seeded with adult primary human mesenchymal stem cells (MSCs), and cultured 10 days in proliferation medium, then 21 days in osteogenic medium. Atomic analyses showed that P15-CSP was successfully captured by LbL. After 2 days of culture, MSCs adhered and spread more on P15-CSP coated pores than PCL-only. At day 10, all constructs contained nonmineralized tissue. At day 31, all constructs became enveloped in a "skin" of tissue that, like 2-D cultures, underwent sporadic mineralization in areas of high cell density that extended into some 141 µm edge pores. By quantitative histomorphometry, 2.5-fold more tissue and biomineral accumulated in edge pores versus inner pores. P15-CSP specifically promoted tissue-scaffold integration, fourfold higher overall biomineralization, and more mineral deposits in the outer 84 µm and inner 141 µm pores than PCL-only (p < 0.05). 3-D Micro-CT revealed asymmetric mineral deposition consistent with histological calcium staining. This study provides proof-of-concept that P15-CSP coatings are osteoconductive in PCL pore surfaces with 3-D topography. Biomineralization deeper than 150 µm from the scaffold edge was optimally attained with the larger 141 µm peptide-coated pores. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2171-2181, 2017.

Rapid fabrication of function-structure-integrated NiTi alloys: Towards a combination of excellent superelasticity and favorable bioactivity

Porous NiTi has brought new expectations to the field of orthopaedic implants due to its excellent mechanical properties such as high strength and superelasticity together with good biocompatibility. In order to facilitate the surrounding bone tissue ingrowth into the implanted porous alloy, reasonably large sized pores and a high amount of porosity are required. There is, however, a major challenge for clinical applications: the higher the porosity, the worse are the mechanical properties and the superelasticity. In this work, therefore, function-structure-integrated NiTi alloys consisting of a central solid and an outer porous layer were fabricated by spark plasma sintering (SPS). When sintered at 750 °C, the NiTi alloy with 14% porosity in the inner part and 49% porosity as well as 350 μm average pore size in the outer layer exhibits an exceptionally high compressive strength (∼1375 MPa), together with an excellent superelastic recovery strain (>4%) and favorable cellular affinity (ROS1728 osteoblasts). Altogether, this work provides a strategy to design materials with function-structure integration and suggests that properly designed function-structure integrated NiTi alloys may be promising as advanced bone implants.

Microfiltration of Synthetic Bacteria Solution Using Low Cost Ceramic Membranes

This work addresses the development and identification of optimal low cost membrane morphologies for bacteria separation applications. Using uniaxial dry compaction method, ceramic membranes (CM1–CM3) were prepared using kaolin, quartz, calcium carbonate, sodium carbonate, boric acid, sodium metasilicate, and poly-vinyl alcohol (PVA) precursors. The fabricated membranes possessed diverse pore morphologies (0.7-4.5 μm average pore size and 39.4–19.3% porosity). Amongst all membranes, the CM3 membrane with wide pore morphology (average pore size of 4.5 μm and porosity of 19.3%) provided the best performance during the direct-flow MF of synthetic Escherichia coli (DH5α strain) solutions. The CM3 membrane provided a trans-membrane flux varying from 1.21 × 10− 2 –3.51 × 10−3 m3/m2.s after 10 minutes of direct-flow MF for a variation in feed concentrations of 0.004 –14.9 × 106 CFU/mL. Corresponding bacterial removal efficiency and log10 reduction value (LRV) values varied from 99-99.9999% and 2-6 respectively. Further, various fouling models have been evaluated for their use in measuring flux decline data. The results indicated that both membrane pore morphologies and concentration of E. coli strains significantly influenced the measured transmembrane flux, fouling index, and separation efficiency.

Osteoconductivity and osteoinductivity of porous hydroxyapatite coatings deposited by liquid precursor plasma spraying: in vivo biological response study

The beneficial effect of a porous structure on the biological functions of calcium phosphate bulk ceramic or scaffold has been well documented. Nevertheless, the effect of a porous structure on the in vivo performance of hydroxyapatite (HA) coatings has been rarely reported, partly due to the difficulty in synthesizing porous HA coatings suitable for commercial applications. In this study, we have carried out a systematic in vivo study of porous HA-coated Ti implants (with and without surface modification) prepared by the liquid precursor plasma spraying process, in terms of its osteoconductivity and osteoinductivity. The results suggest the clear advantage of the porous structure over the dense structure, despite the pore structure (about 48% porosity and less than 100 μm average pore size) being far from the ideal pore structure reported for bulk ceramic. The porous HA-coated implant significantly promotes early bone ingrowth at the pre-generated defective region, and early fixation at the bone–implant interface, especially at early implantation time (one month), showing about 120% and 40% increases respectively over those of the dense HA-coated implants prepared by the conventional atmospheric plasma spraying process. Moreover, the porous structure can be readily used to incorporate collagen/rh-BMP2, which demonstrates clear ectopic bone formation. Overall, the results suggest the augmentation of bone ingrowth is significant for HA coatings with a porous structure, which is critical for the early fixation and long-term stability of medical implants.