Recent Patents on Materials Science - Volume 1, Issue 2, 2008

Amino acids are a significant class of compounds in a number of different application areas, including pharmaceuticals, nutrition, and nonlinear optical materials. Nearly all amino acids are chiral molecules, and appear in Dand L-forms (enantiomers) which are mirror images of each other and thus share the same chemical properties (if they do not interact with another chiral molecule), apart from their optical rotation. Although the α-amino acids are ubiquitous in natural materials, industrially it is more convenient to produce them with chemical syntheses, which typically are not specific to a desired enantiomer and therefore produce a racemic mixture having equal quantities of the two enantiomers. In most applications of the materials a pure enantiomeric form is required and thus the racemic mixture must be separated into its component enantiomers, a process which is typically known as optical resolution. Optical resolution is often a difficult process because the components separated have identical properties, however a range of ingenious techniques has been developed to perform the resolution. This article reviews the patented techniques to achieve optical resolution of amino acids using methods involving crystallization from solution. These methods represent the most industrially significant resolution methods, in particular preferential crystallization and crystallization of diastereomer salts. A short summary of several types of techniques not using crystallization is also presented.

During the last decades, magnetite nanoparticles have been in the focus of a tremendous amount of research due to their biocompatibility and excellent magnetic properties, and numerous applications have been reported. Importantly, advances in the synthesis of magnetite nanoparticles enable excellent control over their size, shape and composition. However, despite remarkable progresses in controlling the synthesis, functionalization and application of magnetite nanoparticles, many issues remain to be overcome for these nanotechnology-products to revolution the medical practice. The fine control and application of colloidal nanostructures such as magnetite nanoparticles in complex biological systems remains especially challenging. This article reviews the current literature and patent base of magnetite nanoparticle's preparation and use, with a special emphasis on biomedical applications. The articles refers to the US patent numbers 4452773, 4554088, 4628037, 4654267, 4672040, 4695392, 4695393, 4770183, 4795698, 4827945, 4951675, 5069216, 5219554, 5262176, 5314679, 5759793, 6048515, 6203777, 6207133, 6,479033, 6479146, 6514481, 6576221, 6599498, 6767635, 6773812, 6962685, 6997863, 7074175, 7128891, 7147742, 7175912, 7208134, and 7273580, as well as European patent number EP1494028.

Wood products used in outdoor applications are treated with biocides to prevent biodegradation by many different fungi and insects. Environmental and disposal concerns have resulted in a rapid and dramatic worldwide shift from the older first-generation preservatives to copper-based systems for residential applications, where the copper(II) is complexed with an organic amine. In the last year the alkaline amine formulation has been partially replaced by microdispersed copper systems that offer several advantages. The current trend in wood preservation is directed towards combining two or more organic biocides in a waterborne formulation employing relatively benign and expensive agrochemicals, with non-biocidal additives sometimes added for increased efficacy and/or other benefits. This review discusses the patents and developments in the past 10 years in biocidal waterborne or solventborne wood protection systems for pressure-treating solid or composite wood products in exterior above-ground or ground-contact applications. Only totally organic systems and related recent developments are discussed, with the exception of microdispersions to formulate both metallic and organic systems.

Orthodontic brackets comprise the basic medium of transmission of force to teeth in orthodontics; this is achieved by the development of loads from activated archwire into the bracket slot. As a standard manufacturing process, brazing alloys to join the base and wing components of brackets are adopted by the industry. Some of these alloys also contain traces of the cytotoxic cadmium, which is added to lower the melting temperature and improve wetting. Moreover, silver-based brazing alloys form a galvanic couple that can lead to ionic release, mainly copper and zinc. Corrosion, which has been substantially minimized in current materials, is the main reason for the progressive dissolution of brazing filler metal, leading to detachment of the wing from the bracket base during orthodontic therapy or at the debonding stage. To overcome this problem, several manufacturers have introduced gold-based brazing materials that might lead to the dissolution of stainless steel, because of the formation of the galvanic couple. Thus, although brazing alloys can facilitate the manufacturing of brackets with alloys of certain properties, e.g., a stiffer alloy for the wing to withstand the loads from activated wires and a softer alloy for the base to facilitate a peel-off effect during debonding-they have several problems. Laser welding was relatively recently introduced in bracket manufacturing as an alternative to alloy soldering. With this method, welding of the wing to the base does not extend to the bulk material, and thus a “surface seal” is formed that is confined to the periphery of the joint. This technique eliminates the intermediate phases such as soldering alloys and shows acceptable mechanical performance with a low risk of joint failure. The metal injection molding (MIM) process, which has significantly expanded during the past few years, involves mixing metal powders with particle sizes of a few microns with organic binders, lubricants, and dispersants to obtain a homogeneous mixture. Injection of the feedstock is performed by using an injection-molding machine, similar to that used in the plastics industry. MIM-manufactured products are one-piece appliances with tolerances of the desired dimensions of approximately 0.3% and density values more than 97% of the theoretical density of the material. Porosity is a known defect of MIM parts, with adverse effects on the mechanical and corrosion resistance of most MIM-manufactured products. The hardness of the MIM-made brackets tested varied from 154 to 287 HV, a value much lower than the hardness of wing components of conventional stainless steel brackets, introducing the problems associated with soft and compliant wing components, as noted previously. This paper reviews the available evidence recent patent on bracket manufacturing with specific reference to limitations of each method from metallurgical and application perspectives.

The continuing quest for increased combustion temperatures within aerospace gas turbines has led to a flurry of R&D activities. The contribution is aimed at providing insight into most recent developments in terms of materials selection, processing technologies, in-service performance, and application of heat-insulating ceramics with (1) high melting point, (2) low coefficient of thermal conductivity, (3) high coefficient of thermal expansion, (4) resistance to solid particle erosion (SPE), (5) high thermal shock resistance, and (6) oxidation resistance. The survey of patented research in the area of thermal barrier coatings described below covers the period from 2006 to early 2008 even though several earlier patents have also been considered when appropriate.

Since the inception of the concept of microemulsions by Hoar and Schulman in 1940, they have always been a key area of interest, both in terms of basic research as well as in industry, which is primarily due to their unique characteristics like thermodynamic stability, optical clarity, and ease of preparation. The existence of microdomains of different polarity with in the same, single-phase solution enables both water-soluble and oil-soluble materials to be solubilized, at the same time. Thus, owing to these features, the uses and applications of microemulsions have been numerous. It is, thus, the objective of this review to summarize the industrial applications of these novel surfactant systems by discussing the patents governing various applications of these systems.

The increasing concerns for climate change and exhausting supply of traditional energy sources have triggered world-wide research efforts in developing alternative energy generation systems. Photocatalytic process for clean electricity/H2 generation and environmental pollution purification has been considered as one of the most promising solutions to address these key challenges that mankind faces. Among various semiconducting photocatalysts, TiO2 has been recognized as the best candidate to date. In this review, we first introduce the basic mechanisms of photocatalytic reactions addressing the processes of electron-hole generation, recombination, charge transfer and surface redox reactions; followed by the preparation of nanostructured TiO2 and their band-gap/surface modification towards visible light response photocatalytic activity, with a main focus on representative research works and patenting activities. The second part overviews some typical applications of TiO2 which include water splitting for H2 production, air and water pollutant purification, self-cleaning coating and dye-sensitized solar cells. Directing the future scientific and applied research efforts toward rational design of this photocatalyst will play a key role in achieving efficient utilization of solar energy for environmental and energy conversion applications.

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