The impact of PET microplastic fibres on PVDF ultrafiltration performance - A short-term assessment of MP fouling in simple and complex matrices.

Wastewater treatment plants (WWTPs) are key components for the capture of microplastics (MPs) before they are released into natural waterways. Removal efficiencies as high as 99% may be achieved but sub-micron MPs as well as nanoplastics have been overlooked because of analytical limitations. Furthermore, short MP fibres are of concern because of their low capture rate as well as the lack of understanding of their influence on purification system efficiency. This study has investigated the impact of poly(ethylene terephthalate) (PET) short nanofibres on the performance of polyvinylidene fluoride (PVDF) ultrafiltration membranes during cross-flow operation. Model MP fibres with an average length of 10 ± 7 µm and a diameter of 142 ± 40 nm were prepared via a combination of electrospinning and fine cutting using a cryomicrotome. The manufactured MPs were added to both pure and synthetic domestic wastewater at a concentration of 1 mg.L-1 to determine their impact on the performance of PVDF ultrafiltration membranes. The results show that PET fibres attach to the membrane in a disorganised manner with low pore coverage. The water flux was decreased by 8% for MPs in pure water and no noticeable effect in wastewater after 3 days of filtration. Additionally, the nutrient removal efficiency of the membrane was not altered by the presence of PET MPs. These findings show that MP fibres do not significantly influence the early stages of filtration for a standard concentration of MPs in wastewater treatment plant studies.

Ultrastrong nanotwinned titanium alloys through additive manufacturing.

Titanium alloys, widely used in the aerospace, automotive and energy sectors, require complex casting and thermomechanical processing to achieve the high strengths required for load-bearing applications. Here we reveal that additive manufacturing can exploit thermal cycling and rapid solidification to create ultrastrong and thermally stable titanium alloys, which may be directly implemented in service. As demonstrated in a commercial titanium alloy, after simple post-heat treatment, adequate elongation and tensile strengths over 1,600 MPa are achieved. The excellent properties are attributed to the unusual formation of dense, stable and internally twinned nanoprecipitates, which are rarely observed in traditionally processed titanium alloys. These nanotwinned precipitates are shown to originate from a high density of dislocations with a dominant screw character and formed from the additive manufacturing process. The work here paves the way to fabricate structural materials with unique microstructures and excellent properties for broad applications.

Effect of Surface Roughness on Hydrodynamic Characteristics of an Impinging Droplet.

The influence of surface roughness and impact energy on the hydrodynamic behavior of water droplets impinging upon dry and rigid surfaces of known roughness has been investigated experimentally. The influence of these two parameters on the droplet maximum spreading diameter, slip length during droplet recoil, dynamic contact angle, contact angle hysteresis, and apparent contact angle of droplets at rest has been determined. Based on the quantitative assessment, a correlation for the maximum spreading diameter in terms of the nondimensional parameter (We/Oh) and surface roughness ratio (Ra/do) was derived. We propose to use surface roughness "Ra" rather than using the contact angle for correlation as contact angles cannot be known a priori, whereas surface roughness can be determined beforehand. The wetting state of a droplet depends on the combined influence of droplet impact energy and surface roughness. While increasing impact energy increases the spreading, higher surface roughness resists the droplet from spreading. Low impact energy and a smoother surface tend toward the Cassie-Baxter wetting state, whereas high impact energy and rough surfaces propel the droplet toward the Wenzel state of wetting.

Tailoring One-Pass Asymmetric Rolling of Extra Low Carbon Steel for Shear Texture and Recrystallization.

Systematic single pass rolling experiments were carried out at room temperature on extra low carbon steel by varying the roll diameter ratio between 1:1 to 1:2 and thickness reduction per pass in the range of 20-75%. The aim of this study was to define the conditions under which the rolling texture can transit into a shear texture. The consequences for grain fragmentation, tensile strength, recrystallization texture, and grain growth kinetics were also studied. It was found that in a certain range of thickness reduction per pass and asymmetric ratio, an effective rotation towards the shear texture takes place in conventional rolling. The value of the shear coefficient factor (shear strain rate/rolling strain rate) in asymmetric rolling depends on the selection of thickness reduction per pass. The measured value of shear coefficient was found to be independent of the number of passes used in asymmetric rolling. The consequence of arising shear textures is an acceleration of grain fragmentation. After rapid heat treatment, both tensile strength and recrystallization kinetics of asymmetric rolled sheets showed merits over the conventional rolling. Only the evolved Goss orientation from asymmetric conditions of deformation shows higher stability than any other preferred shear texture components after complete recrystallization.

An in-situ small angle x ray scattering analysis of nanopore formation during thermally induced chemical dealloying of brass thin foils.

The development of non-noble nano-porous metal materials is hindered by surface oxidation reactions and from the difficulty to generate long range order pore arrays. Dealloying is a promising route to generate such materials by selective chemical etching of metal alloy materials. This process can generate nano-metal materials with superior plasmonic, catalytic and adsorptive surface properties. Here, the impact of properties of the etching solution on the dealloying process to generate nano-pores across thin film alloys was investigated by in-situ SAXS dealloying experiments. Single phase CuZn alloys were used as model materials to evaluate the influence of the solution temperature on the pore formation kinetics. This novel analysis allowed to visualize the change in surface properties of the materials over time, including their surface area as well as their pore and ligament sizes. The dealloying kinetics at the very early stage of the process were found to be critical to both stable pore formation and stabilization. SAXS in-situ data were correlated to the morphological properties of the materials obtained from ex-situ samples by Rutherford back scattering and scanning electron microscopy.

Short Review on Porous Metal Membranes-Fabrication, Commercial Products, and Applications.

Porous metal membranes have recently received increasing attention, and significant progress has been made in their preparation and characterisation. This progress has stimulated research in their applications in a number of key industries including wastewater treatment, dairy processing, wineries, and biofuel purification. This review examines recent significant progress in porous metal membranes including novel fabrication concepts and applications that have been reported in open literature or obtained in our laboratories. The advantages and disadvantages of the different membrane fabrication methods were presented in light of improving the properties of current membrane materials for targeted applications. Sintering of particles is one of the main approaches that has been used for the fabrication of commercial porous metal membranes, and it has great advantages for the fabrication of hollow fibre metal membranes. However, sintering processes usually result in large pores (e.g., >1 µm). So far, porous metal membranes have been mainly used for the filtration of liquids to remove the solid particles. For porous metal membranes to be more widely used across a number of separation applications, particularly for water applications, further work needs to focus on the development of smaller pore (e.g., sub-micron) metal membranes and the significant reduction of capital and maintenance costs.

Effects of Processing Conditions on Texture and Microstructure Evolution in Extra-Low Carbon Steel during Multi-Pass Asymmetric Rolling.

Multi-pass rolling was carried out on extra-low carbon steel at room temperature by imposing different ratios of asymmetry in the roll-diameters as well as by conventional mode. The aim of this study is to understand the effect of shear deformation due to the asymmetric conditions on the development of the rolling texture and the possibilities of propagating the shear deformation into the mid-thickness area of the sheet. The trends of the measured texture developments in both symmetric and asymmetric rolling indicate their dependence primarily on the stability and fraction of the Goss {110}<001> and the rotated cube {001}<111> orientations. The effects of asymmetry conditions were further examined on the microstructure evolution and were correlated to the increased orientation inhomogeneity and grain fragmentation. Both texture and microstructure development showed their dependence on the applied thickness reduction per pass, on the total thickness reduction of the sheet as well as on the degree of the imposed asymmetry. It was found that shear textures can be obtained by asymmetric rolling at conditions where all three parameters-asymmetry ratio, strain in one pass, and the total accumulated strain-are as large as possible.

Insights into Free Volume Variations across Ion-Exchange Membranes upon Mixed Solvents Uptake by Small and Ultrasmall Angle Neutron Scattering.

Ion-exchange membranes are composite separation materials increasingly used in a variety of electro-membranes and electrochemical processes. Although promising for solvent reclamation, to date, their main applications are limited to aqueous environments due to physicochemical and microstructural changes of the materials upon exposure to nonaqueous and mixed solvents solutions, affecting long-term stability and separation performance. In the present work, the structural changes of commercial and novel hybrid ion-exchange membranes in mixed methanol/water and ethanol/water solutions are assessed for the first time using ultra- and small-angle neutron scattering techniques. The interface between the ion-exchange functional layer and the mechanical support of the membranes is evaluated in the ultralow-q region, while a broad solvent-dependent peak at the mid-q region was correlated to the microstructural properties which are related to the free volume across the ion-exchange domains and to the materials electrical and nanoscale mechanical properties. The results of this study may offer new opportunities toward the development of an efficient separation process using ion-exchange membranes for the purification of fermentation broths toward biofuel generation.

Insights into Surface Interactions between Metal Organic Frameworks and Gases during Transient Adsorption and Diffusion by In-Situ Small Angle X-ray Scattering.

The fabrication of molecular gas sieving materials with specific affinities for a single gas species and able to store large quantities of materials at a low or atmospheric pressure is desperately required to reduce the adverse effects of coal and oil usage in carbon capture. Fundamental understanding of the dynamic adsorption of gas, the diffusion mechanisms across thin film membranes, and the impact of interfaces play a vital role in developing these materials. In this work, single gas permeation tests across micro-porous membrane materials, based on metal organic framework crystals grown on the surface of carbon nanotubes (ZiF-8@CNT), were performed for the first time in-situ at the Australian Synchrotron on the small angle X-ray scattering beamline in order to reveal molecular sieving mechanisms and gas adsorption within the material. The results show that specific chemi-sorption of CO2 across the ZiF-8 crystal lattices affected the morphology and unit cell parameters, while the sieving of other noble or noble like gases across the ZiF-8@CNT membranes was found to largely follow Knudsen diffusion. This work demonstrates for the first time a novel and effective technique to assess molecular diffusion at the nano-scale across sub-nano-porous materials by probing molecular flexibility across crystal lattice and single cell units.

A Review on the Assessment of Stress Conditions for Simultaneous Production of Microalgal Lipids and Carotenoids.

Microalgal species are potential resource of both biofuels and high-value metabolites, and their production is growth dependent. Growth parameters can be screened for the selection of novel microalgal species that produce molecules of interest. In this context our review confirms that, autotrophic and heterotrophic organisms have demonstrated a dual potential, namely the ability to produce lipids as well as value-added products (particularly carotenoids) under influence of various physico-chemical stresses on microalgae. Some species of microalgae can synthesize, besides some pigments, very-long-chain polyunsaturated fatty acids (VL-PUFA,>20C) such as docosahexaenoic acid and eicosapentaenoic acid, those have significant applications in food and health. Producing value-added by-products in addition to biofuels, fatty acid methyl esters (FAME), and lipids has the potential to improve microalgae-based biorefineries by employing either the autotrophic or the heterotrophic mode, which could be an offshoot of biotechnology. The review considers the potential of microalgae to produce a range of products and indicates future directions for developing suitable criteria for choosing novel isolates through bioprospecting large gene pool of microalga obtained from various habitats and climatic conditions.

The isolation and identification of new microalgal strains producing oil and carotenoid simultaneously with biofuel potential.

Taxonomy and phylogeny of twenty two microalgal isolates were examined using both universal and newly designed molecular primers. Among the isolates, Scenedesmus bijugus, Coelastrella sp., Auxenochlorella protothecoides, and Chlorella sp. were particularly promising in terms of producing lipids as measured by fatty acid methyl esters (FAME) analysis and significant concentration of carotenoids. A comparative experiment showed that S. bijugus and Chlorella sp. were the most promising candidates (L(-)(1)d(-)(1), with biomass) 174.77±6.75, 169.81±5.22mg, lipids 40.14±3.31, 39.72±3.89mg, lutein 0.47, 0.36mg, and astaxanthin 0.27, 0.18mg respectively. The fatty acids produced by these microalgal isolates were mainly palmitic, stearic, oleic, linoleic, and linolenic acid. The freshwater microalgal isolate S. bijugus be the most suitable isolate for producing biodiesel and carotenoids, due to high productivity of biomass, lipids, metabolites, and its suitable fatty acid profile.

Strontium content and collagen-I coating of Magnesium-Zirconia-Strontium implants influence osteogenesis and bone resorption.

OBJECTIVE: Our objective was to study the role of Collagen type-I (Col-I) coating on Magnesium-Zirconia (Mg-Zr) alloys, containing different quantities of Strontium (Sr), in enhancing the in vitro bioactivity and in vivo bone-forming and mineralisation properties of the implants. MATERIALS AND METHODS: MC3T3-E1 osteoblast cell line was used to analyse the in vitro properties of Col-I coated and uncoated alloys. Cell viability analysis was performed by MTT assay; cell attachment on alloy surfaces was studied by scanning electron microscopy (SEM); and gene profiling of bone-specific markers in cells plated on uncoated alloys was performed by Quantitative RT-PCR. In vivo studies were performed by implanting 2-mm-sized cylindrical pins of uncoated and coated alloys in male New Zealand white rabbits (n = 33). Bone formation and mineralisation was studied by Dual Energy X-ray Absorptiometry (DXA) and histological analysis at one and three months post-implantation. RESULTS: Our results clearly showed that Sr content and Col-I coating of Mg-Zr-Sr alloys significantly improved their bone inducing activity in vitro and in vivo. Osteoblasts on coated alloys showed better viability and surface binding than those on uncoated alloys. Sr inclusion in the alloys enhanced their bone-specific gene expression. The in vivo activity of implants with higher Sr and Col-I coating was superior to uncoated and other coated alloys as they showed faster bone induction and higher mineral content in the newly formed bone. CONCLUSION: Our results indicate that bone-forming and mineralising activity of Mg-Zr-Sr implants can be significantly improved by controlling their Sr content and coating their surface with Col-I.

Microstructures, mechanical and corrosion properties and biocompatibility of as extruded Mg-Mn-Zn-Nd alloys for biomedical applications.

Extruded Mg-1Mn-2Zn-xNd alloys (x=0.5, 1.0, 1.5 mass %) have been developed for their potential use as biomaterials. The extrusion on the alloys was performed at temperature of 623K with an extrusion ratio of 14.7 under an average extrusion speed of 4mm/s. The microstructure, mechanical property, corrosion behavior and biocompatibility of the extruded Mg-Mn-Zn-Nd alloys have been investigated in this study. The microstructure was examined using X-ray diffraction analysis and optical microscopy. The mechanical properties were determined from uniaxial tensile and compressive tests. The corrosion behavior was investigated using electrochemical measurement. The biocompatibility was evaluated using osteoblast-like SaOS2 cells. The experimental results indicate that all extruded Mg-1Mn-2Zn-xNd alloys are composed of both α phase of Mg and a compound of Mg7Zn3 with very fine microstructures, and show good ductility and much higher mechanical strength than that of cast pure Mg and natural bone. The tensile strength and elongation of the extruded alloys increase with an increase in neodymium content. Their compressive strength does not change significantly with an increase in neodymium content. The extruded alloys show good biocompatibility and much higher corrosion resistance than that of cast pure Mg. The extruded Mg-1Mn-2Zn-1.0Nd alloy shows a great potential for biomedical applications due to the combination of enhanced mechanical properties, high corrosion resistance and good biocompatibility.

High-efficient production of boron nitride nanosheets via an optimized ball milling process for lubrication in oil.

Although tailored wet ball milling can be an efficient method to produce a large quantity of two-dimensional nanomaterials, such as boron nitride (BN) nanosheets, milling parameters including milling speed, ball-to-powder ratio, milling ball size and milling agent, are important for optimization of exfoliation efficiency and production yield. In this report, we systematically investigate the effects of different milling parameters on the production of BN nanosheets with benzyl benzoate being used as the milling agent. It is found that small balls of 0.1-0.2 mm in diameter are much more effective in exfoliating BN particles to BN nanosheets. Under the optimum condition, the production yield can be as high as 13.8% and the BN nanosheets are 0.5-1.5 µm in diameter and a few nanometers thick and of relative high crystallinity and chemical purity. The lubrication properties of the BN nanosheets in base oil have also been studied. The tribological tests show that the BN nanosheets can greatly reduce the friction coefficient and wear scar diameter of the base oil.

Collagen type-I leads to in vivo matrix mineralization and secondary stabilization of Mg-Zr-Ca alloy implants.

Biodegradable magnesium-zirconia-calcium (Mg-Zr-Ca) alloy implants were coated with Collagen type-I (Coll-I) and assessed for their rate and efficacy of bone mineralization and implant stabilization. The phases, microstructure and mechanical properties of these alloys were analyzed using X-ray diffraction (XRD), optical microscopy and compression test, respectively, and the corrosion behavior was established by their hydrogen production rate in simulated body fluid (SBF). Coll-I extracted from rat tail, and characterized using fourier transform infrared (FT-IR) spectroscopy, was used for dip-coating the Mg-based alloys. The coated alloys were implanted into the femur bones of male New Zealand white rabbits. In vivo bone formation around the implants was quantified by measuring the bone mineral content/density (BMC/BMD) using dual-energy X-ray absorptiometry (DXA). Osseointegration of the implant and new bone mineralization was visualized by histological and immunohistochemical analysis. Upon surface coating with Coll-I, these alloys demonstrated high surface energy showing enhanced performance as an implant material that is suitable for rapid and efficient new bone tissue induction with optimal mineral content and cellular properties. The results demonstrate that Coll-I coated Mg-Zr-Ca alloys have a tendency to form superior trabecular bone structure with better osteoinduction around the implants and higher implant secondary stabilization, through the phenomenon of contact osteogenesis, compared to the control and uncoated ones in shorter periods of implantation. Hence, Coll-I surface coating of Mg-Zr-Ca alloys is a promising method for expediting new bone formation in vivo and enhancing osseointegration in load bearing implant applications.

Enhancing the electrochemical performance of the LiMn(2)O(4) hollow microsphere cathode with a LiNi(0.5)Mn(1.5)O(4) coated layer.

Spinel cathode materials consisting of LiMn2 O4 @LiNi0.5 Mn1.5 O4 hollow microspheres have been synthesized by a facile solution-phase coating and subsequent solid-phase lithiation route in an atmosphere of air. When used as the cathode of lithium-ion batteries, the double-shell LiMn2 O4 @LiNi0.5 Mn1.5 O4 hollow microspheres thus obtained show a high specific capacity of 120 mA h g(-1) at 1 C rate, and excellent rate capability (90 mAhg(-1) at 10 C) over the range of 3.5-5 V versus Li/Li(+) with a retention of 95 % over 500 cycles.

Biocompatibility of TiO2 nanotubes with different topographies.

The biological response of osteoblast cells to implant materials depends on the topography and physico-chemistry of the implant surface and this determines the cell behavior such as shaping, adhesion and proliferation, and finally the cell fate. In this study, titanium (Ti) was anodized to create different topographies of titania nanotubes (TNTs) to investigate the cell behavior to them. TNTs with and without a highly ordered nanoporous layer on their top surface were fabricated using two-step and one-step anodizing processes, respectively. The TNTs without a highly ordered nanoporous layer on the top surface exhibited a rougher surface, higher surface energy and better hydrophilicity than the TNTs with such a layer. Osteoblast-like cells (SaOS2) were used to assess the biocompatibility of the TNTs with different topographies in comparison to bare cp-Ti. Results indicated that TNTs can enhance the proliferation and adhesion of osteoblast-like cells. TNTs without a highly ordered nanoporous layer exhibited better biocompatibility than the TNTs covered by such a nanoporous layer. Cell morphology observation using confocal microscopy and SEM indicated that SaOS2 cells that were adhered to the TNTs without the highly ordered nanoporous layer showed the longest filopodia compared to TNTs with a highly ordered nanoporous layer and bare cp-Ti.

Effects of alloying elements on the corrosion behavior and biocompatibility of biodegradable magnesium alloys: a review.

Magnesium (Mg) based alloys have been extensively considered for their use as biodegradable implant materials. However, controlling their corrosion rate in the physiological environment of the human body is still a significant challenge. One of the most effective approaches to address this challenge is to carefully select alloying compositions with enhanced corrosion resistance and mechanical properties when designing the Mg alloys. This paper comprehensively reviews research progress on the development of Mg alloys as biodegradable implant materials, highlighting the effects of alloying elements including aluminum (Al), calcium (Ca), lithium (Li), manganese (Mn), zinc (Zn), zirconium (Zr), strontium (Sr) and rare earth elements (REEs) on the corrosion resistance and biocompatibility of Mg alloys, from the viewpoint of the design and utilization of Mg biomaterials. The REEs covered in this review include cerium (Ce), erbium (Er), lanthanum (La), gadolinium (Gd), neodymium (Nd) and yttrium (Y). The effects of alloying elements on the microstructure, corrosion behavior and biocompatibility of Mg alloys have been critically summarized based on specific aspects of the physiological environment, namely the electrochemical effect and the biological behavior.

Ti-SrO metal matrix composites for bone implant materials.

Titanium-strontia (Ti-SrO) metal matrix composites (MMCs) with 0, 1, 3 and 5% (weight ratio) of SrO have been fabricated through the powder metallurgy method. Increasing the weight ratio of SrO from 0 to 5%, the compressive strength of Ti-SrO MMCs increased from 982 MPa to 1753 MPa, while the ultimate strain decreased from 0.28 to 0.05. The elastic moduli of Ti-3SrO and Ti-5SrO MMCs were higher than those of Ti and Ti-1SrO MMC samples. Additionally, the micro hardness of Ti-SrO MMCs was enhanced from 59% to 190% with the addition of SrO. The enhanced compression strength and micro hardness of Ti-SrO MMCs were attributed to the Hall-Petch effect and the SrO dispersion strengthening in the Ti matrix. MTS assay results demonstrated that Ti-SrO MMCs with 3% SrO exhibited enhanced proliferation of osteoblast-like cells. Alkaline phosphatase activity of cells was not influenced significantly on the surface of Ti-SrO MMCs compared with pure Ti in a term longer than 10 days. The cell morphology on the Ti-SrO MMCs was observed using confocal microscopy and scanning electron microscopy, which confirmed that the Ti-3%SrO MMCs showed optimal in vitro biocompatibility.

Fabrication of Meso-Porous Sintered Metal Thin Films by Selective Etching of Silica Based Sacrificial Template.

Meso-porous metal materials have enhanced surface energies offering unique surface properties with potential applications in chemical catalysis, molecular sensing and selective separation. In this paper, commercial 20 nm diameter metal nano-particles, including silver and copper were blended with 7 nm silica nano-particles by shear mixing. The resulted powders were cold-sintered to form dense, hybrid thin films. The sacrificial silica template was then removed by selective etching in 12 wt% hydrofluoric acid solutions for 15 min to reveal a purely metallic meso-porous thin film material. The impact of the initial silica nano-particle diameter (7-20 nm) as well as the sintering pressure (5-20 ton·m-2) and etching conditions on the morphology and properties of the final nano-porous thin films were investigated by porometry, pyknometery, gas and liquid permeation and electron microscopy. Furthermore, the morphology of the pores and particle aggregation during shear mixing were assessed through cross-sectioning by focus ion beam milling. It is demonstrated that meso-pores ranging between 50 and 320 nm in average diameter and porosities up to 47% can be successfully formed for the range of materials tested.