We are glad to report that the journal impact factor (IF) for Surface Innovations rose to 2.845 from 2.333 in 2019. This is the fourth year in a row when the journal climbs in ranking.
We would like to share with you the content of the fourth issue of 2020 of Surface Innovations. This issue offers Invited Feature Article on plasma surface modifications of orthopedic biomaterials and three original papers on bioresorbable medical materials. Hope many of you will find something interesting among these four quality papers.
Congratulations to our undergraduate researcher for receiving the Graduate School Academic Excellence Award (GAEA) and her acceptance to MTU master’s program. This one-time award of $4,500 will be applied towards Emily’s tuition for the fall 2020 semester.
Well deserved Award Emily!
In a new paper entitled “Nano-scaled roughness effect on air bubble-hydrophilic surface adhesive strength” and published in Colloids and Surfaces A: Physicochemical and Engineering Aspects, we describe the effect of nano-scaled roughness on adhesion of air bubble with hematite and pyrite. This is the result of our collaborative project with Northeastern University in China, and effort of two Chinese scholars, Zhanglei Zhu and Donghui Wang.
Surface roughness of solid affects its interactions with gas bubbles in water. Here, we investigate the effect of surface nano-scaled (random) roughness, quantified with the root-mean-square (RMS) roughness from about 3 to 260 nm, on the adhesive strength of air bubble with natural hydrophilic hematite and pyrite surfaces using a microelectronic balance-camera system. The recorded values include bubble-mineral adhesion forces, water contact angles, and bubble base diameters during stages of air bubble attachment and spreading, maximum adhesion, and detachment. The results confirm weakening of adhesive forces for air bubble with hydrophilic surfaces of increasing nano-scale roughness. The study reveals a linear dependency between adhesion force and RMS roughness. The adhesion force was also found to be in a linear correlation with contact angle and its sine function, providing evidence for the surface tension force dominance in adhesion of bubble to hydrophilic surface with nano-scaled surface roughness characteristics of random nature.
Dr. Drelich co-authors a paper entitled: “Mechanical properties of Boehmeria nivea natural fabric reinforced epoxy matrix composite preparedby vacuum-assisted resin infusion molding” and published in open-access Polymers journal. This is the most recent result of his collaboration with the Military Institute of Engineering in Rio de Janeiro, Brazil.
Natural lignocellulosic fibers and corresponding fabrics have been gaining notoriety in recent decades as reinforcement options for polymer matrices associated with industrially applied composites. These natural fibers and fabrics exhibit competitive properties when compared with some synthetics such as glass fiber. In particular, the use of fabrics made from natural fibers might be considered a more ecient alternative, since they provide multidirectional reinforcement and allow the introduction of a larger volume fraction of fibers in the composite. In this context, it is important to understand the mechanical performance of natural fabric composites as a basic condition to ensure ecient engineering applications. Therefore, it is also important to recognize that ramie fiber exhibiting superior strength can be woven into fabric, but is the least investigated as reinforcement in
strong, tough polymers to obtain tougher polymeric composites. Accordingly, this paper presents the preparation of epoxy composite containing 30 vol.% Boehmeria nivea fabric by vacuum-assisted resin infusion molding technique and mechanical behavior characterization of the prepared composite. Obtained results are explained based on the fractography studies of tested samples.
A new contribution entitled “Water droplets and air bubbles at magnesite nano-rough surfaces: analysis of induction time, adhesion and detachment using a dynamic microbalance” and published in the Minerals Engineering journal is the result of our collaborative project with Northeastern University in China. Two scholars from China Zhanglei Zhu and Donghui Wang explored the effects of nano-scale roughness of magnesite minaral on adhesion with water droplets and air bubbles.
In this study, natural magnesite lumps were polished by a series of sandpapers and diamond to produce four magnesite specimens having 2 to 240 nm root-mean-square roughness. The dynamic measurements of attachment, spreading, adhesion, and separation with a high-sensitivity microelectronic mechanical balance revealed the effect of surface nano-scaled roughness on the induction time and forces of spreading, adhesion and separation for both water droplets and air bubbles. It was found that the increasing nano-scaled roughness enhances the spreading of water on hydrophilic magnesite and strengthens the water-magnesite adhesive contact. Nano-roughness also causes delays in attachment of air bubbles to magnesite surface, inhibits displacement of water by adhering air bubbles, and reduces the adhesive strength of air bubbles to the magnesite surface, factors that might slow down the flotation separation.
Three members of our team, Dr. Drelich, Dr. Sikora-Jasinska and Dr. Mostaed, have served as guest editors to the JOM journal and prepared a collection of quality papers on Biodegradable Materials for Medical Applications II.
To mitigate the long-term side effects associated with current corrosion-resistant implants, a new generation of bioabsorbable medical devices is currently being developed and have already been approved in some markets (e.g. Europe). Implants made of biodegradable materials are absorbed and excreted by the body after completing their temporary mechanical, scaffolding and biointegration functions. Biochemical and mechanical attributes of all classes of materials including metals, ceramics and polymers have been broadly explored by scientific and industrial research and development laboratories for various clinical applications over the last two decades. The second (bi-annual) international symposium ‘Biodegradable Materials for Medical Applications’ took place during the 2020 TMS Meeting in San Diego and addressed the emerging multi-disciplinary field of biodegradable materials and implants, involving materials scientists and engineers working with biologists, bioengineers and medical personnel. The symposium had four oral sessions with four keynote presentations, seven invited talks and eighteen regular presentations, and a poster session with eleven posters. Papers presented covered a broad range of topics related to materials selection, development, processing, and testing, material surface treatments and modifications, in-vitro/in-vivo performance assessment and evaluation for biodegradable-based implants including vascular, orthopedic, tissue engineering, and other applications, presented by representatives from Canada, China, Germany, Hong Kong, Italy, Poland, Singapore, Slovenia, and the USA. Nearly two dozen selected quality papers were submitted for publication into three journals, including JOM (this issue), Metallurgical and Materials Transactions A (to be published in Volume 51), and Surface Innovations (to be published in Volume 8). Although the papers from the first symposium in this series were not published, last year the April 2019 issue of JOM (vol. 71, no. 4) offered five papers on characterization of biodegradable medical materials.
We have published a new article entitled “Tailoring the mechanical and degradation performances of Mg-2.0Zn-0.5Ca-0.4Mn alloy through microstructure design” in the JOM journal A novel Mg-2.0Zn-0.5Ca-0.4Mn alloy was formulated and processed through melt spinning and hot extrusion to enhance the mechanical and degradation properties. Microstructural characterization on the rapidly solidified alloy ribbons consolidated by extrusion (RS+Ex) revealed a fine and fully recrystallized microstructure with an average size of 4µm. The conventionally extruded (Ex) alloy consisted of several course second phase strips as coarse as 100 µm, while the RS+Ex was devoid of any second phases larger than 100 nm. RS+Ex processing resulted in significantly randomized texture where the majority of the basal planes were tilted toward transverse and extrusion directions. Such a weak texture resulted in higher activity of basal planes and thereby, considerably improved the fracture elongation from 4% to 19 %, while keeping relatively high tensile strength of 294 MPa. In addition to high strength and ductility due to the reduced activity of deformation twining during the compression, the RS+Ex alloy showed lower yielding asymmetric ratio than that measured for Ex alloy (1.25 vs 1.61). Electrochemical measurements and immersion tests indicate that applying RS+Ex remarkably reduces the corrosion rate from 2.49 to 0.37 mm/year due to recrystallization completion and suppression of coarse second phase formation.
Biodegradable arterial implants based on zinc have been found to suppress neointimal hyperplasia, suggesting that biodegradable materials containing zinc may be used to construct vascular implants with a reduced rate of restenosis. However, the molecular mechanism has remained unclear. In this new report from Prof. Jeremy Goldman laboratories entitled Zn2+-Dependent Suppression of Vascular Smooth Muscle Intimal Hyperplasia from Biodegradable Zinc Implants, published in Materials Science and Engineering C, we show that zinc-containing materials can be used to prevent neointimal formation when implanted into the rat aorta. Indeed, neointimal cells were significantly more TUNEL positive and alpha-actin negative at the interface of biodegradable zinc vs. biostable platinum implants, in association with greater caspase-3 activity. Although zinc stimulated extensive neointimal smooth muscle cell (SMC) death, macrophage and proinflammatory markers CD68 and iNOS were not increased in neointimal tissue relative to biostable platinum control implants. Using arterial explants, ionic zinc was confirmed to promote SMC apoptosis by activating the caspase apoptotic signaling pathway. These observations suggest that zinc-containing materials can be used to construct vascular implants such as stents with reduced neointimal hyperplasia.
Our visiting scholar from the Northeastern University in Shenyang published a new paper entitled Effect of Nano-sized Roughness on the Flotation of Magnesite Particles and Particle-Bubble Interactions in the Minerals Engineering journal. In this study, magnesite was ground in stainless-steel disc and ceramic ball mills to produce flotation feed material of different surface nano-roughness, which was quantified using atomic force microscopy (AFM). The effect of surface roughness on the floatability of magnesite particles was carried out by a micro-flotation kinetic test using an XFG flotation machine. The flotation results demonstrated both higher flotation recovery and larger flotation rate constant for particles having larger nano-asperities of rough particle surface. Additionally, the difference in cumulative flotation recovery between magnesite particles with different nano-roughness characteristics systematically decreased with increasing collector (sodium oleate) concentration from 25 to 150 mg/L. Contrarily, a difference in the value of flotation kinetics constant for particles with larger and smaller asperities remained at a level of 0.2-0.3 min-1 for the entire range of collector concentration. The interaction energy between bubbles and rough magnesite particles with different nano-roughness was estimated using an extended DLVO (Derjaguin–Landau–Verwey–Overbeek) theory. The theoretical interaction energy points to lowering energy barrier when the magnesite particles are covered with 12 nm asperities as compared to 2 nm asperities. It is therefore hypothesized that the energy barrier is a primary cause for differences in flotation performance of particles decorated with nano-asperities of different dimensions.