Radionuclide Generators
Garimella V. S. Rayudu, Lelio G. Colombetti in Radiotracers for Medical Applications, 2019
The preparation of alumina columns has been reported in the literature.55 Although, other column materials such as manganese oxide and hydrous zirconium oxide have been proposed, acid alumina is still the material of choice. The alumina can be commercially obtained from Woelm or prepared in the laboratory by treating Al2O3 with a weakly acidic solution (pH 3 to 3.5). The column is loaded with a purified solution of 99Mo-molybdate, usually as ammonium molybdate, whose pH has been reduced to 3 to 3.5 by adding dilute HNO3. A small amount of sodium hypochlorite or hydrogen peroxide is added to the solution to keep the molybdenum in its highest valence state. After loading, the column is washed a few times with saline, until there is no more breakthrough of alumina.
Biomaterials
Manoj Ramachandran, Tom Nunn in Basic Orthopaedic Sciences, 2018
Alumina (AL2O3) and zirconia (ZrO2) are used in bearing surfaces. Alumina and zirconia share abrasion resistance, low friction and high wettability, resulting in a superior bearing surface. Alumina is particularly brittle and historically had a significant rate of fracture (up to 5%), but processing has reduced the grain size and increased density, reducing fracture risk. Zirconia requires a stabilizer, otherwise it is sensitive to phase changes that can cause micro-cracking and reduce its mechanical properties. Heat and resterilization need to be avoided as they can cause surface roughening. Zirconia had accelerated wear in ceramic-on-ceramic bearings and is only designed for ceramic-on-polyethylene use. The original zirconia was withdrawn but oxidized zirconium has improved fracture resistance and is used in femoral heads and total knee replacements. Due to the high Young’s modulus of ceramics compared to cancellous bone, stress shielding can result in failure, particularly when used for the acetabular component.
Bioceramic Nanoparticles for Tissue Engineering
Harishkumar Madhyastha, Durgesh Nandini Chauhan in Nanopharmaceuticals in Regenerative Medicine, 2022
Bioinert ceramics such as alumina ceramic (Al2O3) and zirconia ceramic (ZrO2) possess properties like better chemical stability and inertness in vivo, low friction, wettability, a higher compressive strength, cracking strength and bending strength, corrosion resistance, and better biocompatibility when they are implanted in animal tissues such as bone (Yamamuro 2004). They are specifically used for total knee and hip replacement surgery and for dental repair treatment. Contact osteogenesis occurs when bone comes in contact with the implants (especially all endosseous dental implants) made up of these bioinert ceramics. These engineering ceramic materials have been used since 1970 for dental implants and other osteosynthetic devices such as bone and joint prostheses (Pina et al. 2017, Kurtz et al. 2014). It has been known that alumina or zirconia has high mechanical properties combined with high wear-resistant character. These properties are related to surface smoothness and surface energy. Because of high abrasion resistance properties, the use of the alumina and zirconia is limited to the bearing surface of joint prostheses, for fabrication of porous scaffold and for biomimetic coatings. For maxillofacial applications, alumina ceramics are used for developing jaw bone, ear bone substitutes, and various dental implants (Greenspan 2016) (Pina et al. 2017).
A key role by polymers in microneedle technology: a new era
Published in Drug Development and Industrial Pharmacy, 2021
Amarjitsing Rajput, Madhur Kulkarni, Prashant Deshmukh, Prashant Pingale, Atul Garkal, Sahil Gandhi, Shital Butani
The various types of materials have been used for the preparation of MNs. It includes polymers, metals, silicon, and ceramic [150–153]. Silicon has been applied to prepare hollow, solid, and coated MNs [17]. Silicon suffers from limitations like more production cost [154], a time-consuming preparation method [155], and it also results in fractures in the skin [156]. Metals, such as stainless steel [157] and titanium are also utilized to fabricate the MNs. But MNs manufactured with metals resulted in allergic reactions [158]. Because of excellent chemical characteristics and compression resistance potential, ceramic compounds like alumina have also been utilized in microneedle manufacturing [159]. Moreover, alumina possesses a minimum tensile strength than other materials [30]. On the other hand, polymers serve as potential materials for the fabrication of MNs. They are economical, biocompatible, biodegradable, safer, dissolving, and have swelling capabilities [47,48,160]. Compared to other metals, the most crucial advantage of polymer is the absence of waste generation post-usage [161]. Therefore, polymers are widely used to prepare hollow, solid, coated [17] hydrogel-forming, dissolving [118,162,163] MNs. Thus, looking at all their merits of polymeric microneedle over others, most of the researchers are working to develop microneedle-based drug delivery systems using polymers.
Nanoformulations and their mode of action in insects: a review of biological interactions
Published in Drug and Chemical Toxicology, 2021
Kiran Shahzad, Farkhanda Manzoor
Insecticidal dust are commonly used to protect stored grain (Hagstrum and Phillips 2017). In dust composed of nanostructured alumina (NSA), the mechanism relies on physical disruption instead of biochemical mode of action. Stadler et al. (2017) demonstrated charged NSA particles dehydrate the insect by attaching to their cuticle via triboelectric forces and by surface area effect sorbs its wax layer. Along with their hydrophobic behavior, these abrasive particles also cause splits and scratches on insect bodies (Arumugam et al.2016). Buteler et al. (2015) determined that when using insecticidal dust, parameters such as particle morphology, surface area, and particle size have to be factored in to influence insecticidal activity efficacy.
Facile deposition of biogenic silver nanoparticles on porous alumina discs, an efficient antimicrobial, antibiofilm, and antifouling strategy for functional contact surfaces
Published in Biofouling, 2021
Ozioma Forstinus Nwabor, Sudarshan Singh, Suttiwan Wunnoo, Kowit Lerwittayanon, Supayang Piyawan Voravuthikunchai
Alumina is a commercial compound with good thermal strength, hardness, and resistance to corrosion (Sun et al. 2016; Liu et al. 2018), used for a range of industrial and biomedical applications (Ghaemi et al. 2017; Ackerl et al. 2019; Zou et al. 2019; Carvalho et al. 2020). Alumina ceramics are used as contact surface materials and in the fabrication of pipes, sanitary and household materials. Microbial adhesion to ceramic surfaces triggers biofouling and subsequent microbial influenced corrosion (Nelson et al. 2017). Several studies have investigated modification of surfaces through various methods. However, the in situ method of deposition of nanoparticles has not been extensively investigated.
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