Recent Patents on Materials Science - Volume 10, Issue 1, 2017

Background: Corrosion control of magnesium for biomedical applications can be achieved by two means: deposition of protective coatings that isolate the surface from aggressive human body environment, and alloying the base metal with biocompatible elements that stabilize the surface against deterioration. Objective: This contribution reviews recent research towards efficient corrosion protection of magnesium and its alloys that are being used predominantly in osteosynthetic musculoskeletal fixation devices and cardiovascular stents. Relevant patents granted or applied for between 2010 and the present are being considered, reviewed, and evaluated. Method: The article concentrates on corrosion control coatings deposited on magnesium substrate surfaces by a plethora of surface-modifying methods. These methods include the provision of chemical conversion coatings as well as coatings with composition differing from that of the substrate material. Coating methods described herein include protocols of biomimetic syntheses, sol-gel deposition, galvanic anodization, plasma electrolytic oxidation (PEO), electrophoretic deposition (EPD), pulsed laser deposition (PLD), cold gas dynamic spraying (CGDS), coincident microblasting (CoBlast) technique, and several others. A short paragraph deals with novel magnesium alloys the composition and microstructure of which contribute to corrosion protection of biomedical devices in vivo. Results: Evaluation of recent research reveals that despite many multi-pronged approaches towards developing Mg alloys for biomedical use, much needs to be done to overcome their performance deficiencies in demanding application such as osteosynthetic musculoskeletal fixation devices and cardiovascular stents. Conclusion: At present, much effort is being expended to develop Mg alloys for next generation biomaterials. While there are reasonable solutions for a few biomedical applications, ultimate future achievements may include the use of appropriately designed and engineered magnesium alloys for load-bearing isoelastic endoprosthetic implants.

Background: The nature of graphene makes it a highly sought after material for transparent and non transparent electrodes and double electrode designs for supercapacitors. It has been well documented that graphene can be used for transparent electrodes in flat panel displays, tough screens, and solar cells. In this case of supercapacitors, transparency is less important than energy storage capacity. However, even in this application, graphene has the potential to excel. A significant number of very recent inventions disclose the use of graphene as various electrodes for such applications and are compiled in this review article. Objective: This review article covers the existing knowledge and patent base for manufacturing of graphene as well as the very recent patent base for the use of graphene as transparent electrode for application such as display devices and touch screen and the manufacturing of such devices and graphene based components. Method: The US Patent Base was thoroughly searched in order to review the existing patents on graphene based transparent electrodes for flat panel display devices as well as supercapacitors and their fabrication. Results: A large number of patents disclose the application and fabrication of graphene based flat panel display devices and supercapacitors and their fabrication. In some cases, graphene is not specifically mentioned, but carbon containing materials which include graphene. Just the very recent existing patent base disclosed a wide range of applications based on graphene including flat panel display devices, touch panel devices, and supercapacitors. The article covers more than 40 patents from the period between 2015 and 2017. Conclusion: The significant number of literature and patents, which discloses numerous methods to prepare graphene, fabricate and apply components based on graphene, and manufacture devices based on such components, makes it evident that graphene is considered to be an important material for the next generation of transparent and non transparent electrodes and supercapacitors.

Background: Raw natural gas, one of the most important fuel sources worldwide, contains high level of CO2, which must be removed to avoid problems like pipeline corrosion, compression cost and reduction of heating value. The three main technologies used to separate CO2 from natural gas include cryogenic distillation, amine absorption and membranes. Membrane technologies have various advantages especially for offshore platforms. In recent years, more and more membrane systems have been applied to large offshore natural gas upgrading projects. Two entirely different membrane processes can be applied to the separation of CO2 from natural gas: gas permeation membranes and membrane contactors. Objective: An overview of some recent patents and related scientific literature on both gas permeation membranes and membrane contactors for CO2 removal from natural gas is important to focus on the key points for further advances. Methods: From a thorough literature review of membrane processes for CO2 separation from natural gas, several patents on this application have been identified and here reviewed. Besides, recent papers in the field are discussed. Conclusion: Membrane systems require a relatively small operational area, small amounts of energy, only minor operational efforts with moderate maintenance and inspection requirements. Hence the interest from oil gas industry companies such as UOP, L’Air Liquide, Statoil Petroleum, Aker Process Systems, which are applicants and assignees of most patents for CO2 removal from natural gas by membrane technologies.

Background: Exposure of newly synthesized biomaterials and drugs to humans needs a strict monitoring to minimize or prevent the after effects. One of the commonly used tests in ensuring the safety of new products is cytotoxicity testing. Cytotoxicity testing enables to observe cell growth, viability and morphological effects of biomaterials in vitro. Considering the advantages of the cytotoxicity tests, researchers employ this as a pilot test before applying in animals. Through times, many cytotoxicity assays have been developed which provide more options for the researchers. Objective: This article aims to provide an overview of the different methods employed in cytotoxicity testing. Method: Based on a thorough literature review, various cytotoxicity assays and some patents of application were identified and discussed. Results: The advantages and disadvantages of each cytotoxicity assay were identified that would help the researcher in selecting a suitable assay which can yield a more accurate result and at the same time, minimize both cost and time. Conclusion: The conclusion highlights the relevance of various cytotoxicity assays for selection of an appropriate test.

Background: Bismuth sulfide (Bi2S3) has many smart physical and chemistry properties and potential advantages in optical and electrical applications. To further enhance the application property, many studies had been performed. Objective: This work explained the manufacturing and potential application of the Bi2S3 materials with various cation dopings in recent literature and patent and then focused on the deposition and Cu doping effect of the Bi2S3 films. Method: Undoped and Cu-doped Bi2S3 films were deposited by a modified chemical bath deposition and characterized by X-ray diffraction, scanning electron microscopy, ultraviolet-visible spectrophotometry, photoluminescence spectrophotometry, and electrical conduction measurement. Results: The Cu-doping resulted in direct and indirect optical bandgaps, which first increased and then decreased with Cu-doping content. Moreover, the films showed S/Bi>1.5, p-type conduction, and low electrical resistance. The Cu doping led to a decrease in the resistance by increasing Cu content. The films also showed strong bandgap emission and two weak visible emissions related to the defects. The refractive index, extinction coefficient, optical conductivity, and dielectric constant of the films were calculated from the transmittance and reflectance spectra. The present article discussed some important patents related to Bi2S3 thin films Conclusion: By controlling the S/Bi ratio and doping appropriate amount of Cu cation, the optical and electrcical properties can be tuned and enhanced.

Background: Research in the field of orthopedics is trying to evaluate the materials for an artificial joint with minimum wear volume loss, so as to extend the life. Various material combinations are proposed to overcome this issue. Silicon nitride (Si3N4) is non-oxide ceramic suggested as a new alternative for hip/knee joint. Objective: In this paper, an attempt has been made to evaluate the optimum proportion of load and % volume of hexagonal boron nitride (hBN) in Si3N4 to minimize wear volume loss (WVL). Method: From a thorough review of literature in the field of biomaterials, several patents of application of silicon nitride as the alternative material for hip/knee joint replacement are identified and discussed herewith. To determine the wear performance of Si3N4-hBN, the experiments were conducted according to Design of Experiments (DoE) 128;“ Taguchi method and a mathematical model is developed. Further, this model is processed with GA to find out the optimum percentage of hBN in Si3N4 to minimize wear volume loss against steel (ASTM 316L) counterface. Results: Taguchi method presents 15N load and 12% volume of hBN to minimize WVL of Si3N4. GA optimization offers 18.452N load and 8.46% volume of hBN to minimize WVL in Si3N4.

Background: Hydrogen energy is a solution for the energy crisis. As it is known, the result of hydrogen combustion is water vapor. This means that there is no pollution. Objective: This study investigates hydrogen production of pure aluminum (Al) and aluminum -silicon alloy (Al-Si). The investigation has been processed in the presence of 10% and 15% of sulphuric acid (H2SO4) at room temperature50°C. Methods: Weight loss measurements, logical calculations and scanned surfaces have been applied as tools for investigation. Scanning electron microscope and X-ray Diffraction (XRD) have been used for investigating crystal structure and surface morphology, respectively. Results and Conclusion: Hydrogen production of pure Al and Al-Si alloy is affected by some factors, such as H2SO4 concentrations, temperature and immersion time. As observed, the hydrogen production of the pure Al and Al-Si alloy is nearly similar during the first hour of immersion. Pure Al produces amounts of hydrogen more than Al-Si alloy, especially in 15% H2SO4 at 50°C and after 5 hours of sample immersion. Adherent and strong passive oxide layer forms on the Al surface. This passive layer protects the surface from corrosion during first hour of immersion at RT, but hydrogen production rate increases with increasing temperature and acid concentration. SEM measurement shows surface roughness due to oxide film breakdown. XRD shows the effect of experimental conditions, immersion time, acid concentration and temperature, on the crystal phases of the Al and its alloy.