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Imaging in oncology
Published in David A Lisle, Imaging for Students, 2012
Percutaneous tumour ablation may be used to treat tumours of the liver, kidney, breast, bone or lung. US, CT or MRI may be used for procedure guidance. A variety of ablation techniques is available under three broad categories:Injection of substances that cause cell death, such as ethanol or heated salineHeatingRadiofrequency ablationInterstitial laser therapyMicrowave coagulationHigh intensity focused ultrasound (HIFU)Freezing: cryotherapy.
Surface Treatments of Load Bearing Bio-implant Materials
Published in Savaş Kaya, Sasikumar Yesudass, Srinivasan Arthanari, Sivakumar Bose, Goncagül Serdaroğlu, Materials Development and Processing for Biomedical Applications, 2022
K. Saranya, P. Agilan, M. Kalaiyarasan, N. Rajendran
Laser sources are used to tailor the favorable surface properties on the metal surfaces without changing the fundamental properties of a material. Laser ablation is a widely used technique to remove or restructure a portion of the material to create a micro- or nano-patterned material using a laser beam. Laser treatment is a quick and precise process for the formation of the ideal structures in the biomedical field (Shivakoti et al. 2021). Pulse frequency, intensity of the lamp and scan speed play a substantial role that influences the surface roughness of the implant (Mohammad et al. 2016). Laser ablation fabricates the micro-textured grooves which are 30–50 µm in width and 15–50 µm deep on ZrO2, increasing the surface wettability (Liu et al. 2017). Roy et al. (2008) reported tri-calcium phosphate (TCP) coated Cp-Ti by laser treatment enhanced the bone cell interaction with bio-implant material. Yu et al. (2018) demonstrated that the micro-texture formed by picosecond laser ablation on Ti6Al4V alloy exhibited good biofunctionalization and better mesenchymal stem cell adhesion on the micro-groove of the Ti surface. Ti and Mg alloys engineered with functional bioactive materials by laser micro-processing method showed improved cell attachment and better corrosion resistance (Hu et al. 2018). Pereira et al. (2020) studied that laser ablation is a suitable process for the fabrication of hydrophilic surfaces on ceramics. The laser textured Ti6Al4V and 316L SS coated with hydroxyapatite offered more corrosion resistance and good cell interaction (Stango et al. 2018).
Undoped Tetrahedral Amorphous Carbon (ta-C) Thin Films for Biosensing
Published in Klaus D. Sattler, st Century Nanoscience – A Handbook, 2020
Anja Aarva, Miguel Caro, Tomi Laurila
High sp3-containing a-C films (namely tetrahedral amorphous carbon ta-C) are typically fabricated with three main approaches: (i) pulsed DC sputtering, (ii) different types of arc processes and (iii) various laser ablation methods. We will not go into details of any one of these methods as these have been summarized in detail, for example in Ref. [12,13]. We just point out here that one of the main features or challenges in arc processes is the unavoidable presence of macroparticles in the films even if different types of filters are utilized. These will of course have an effect on the film properties and material performance in many applications. Pulsed DC sputtering on the other hand is relatively free of any kind of macroparticles. However, at the same time arc techniques are the methods of choice if one really targets a high sp3-containing a-C film, which cannot be obtained with most of the other methods. Whatever is the method used to fabricate the ta-C thin films, the following parameters should be determined and controlled as they heavily influence the properties of the resulting films: (i) distribution of energetic species involved, (ii) their energy and incidence angle, (iii) background pressure during deposition, (iv) trace impurities in the system, (v) substrate temperature and (vi) deposition rate. As the study of the atomistic picture of film growth experimentally is next to impossible, many efforts have been made to provide an explanation for the film growth phenomena based on computational simulations. Unfortunately, due to the limitations of classical potentials, which are computationally efficient, but lack accuracy in describing bond formation, and the high computational cost associated with ab initio methods, which could describe the flexible bonding environment, these efforts have failed to provide any definitive answers.
Use of nanomaterial for asphalt binder and mixtures: a comprehensive review on development, prospect, and challenges
Published in Road Materials and Pavement Design, 2021
Prabin Kumar Ashish, Dharamveer Singh
A carbon nanotube is essentially made up of sheets of graphite (an allotrope of carbon) rolled up in a tubular structure with very high aspect ratio, significantly higher than any other existing material (Wang et al., 2009). CNT was firstly discovered and characterise by Iijima (1991). The diameter of CNT found to be as low as 0.4 nm to up to several hundred nanometres (Bai & Allaoui, 2003). CNT possess unique mechanical properties. For example, tensile strength for CNT has been reported anywhere in the range of 11 to 63 GPa (Yu et al., 2000a). The tensile failure strain of CNT has been reported as close to 5.5% (Yu, Files, Arepalli, & Ruoff, 2000b). Young’s modulus of CNT has been reported anywhere in the range of 15–50 GPa (Treacy, Ebbesen, & Gibson, 1996). Such an excellent mechanical property signifies CNT as an ideal choice for various structural purposes (Larsen-Basse & Chong, 2006; Steyn, 2009). Based upon the number of rolled graphene sheets, CNT can be divided into single wall CNT and multi-wall CNT, manufactured using mainly three different approaches namely (a) arc discharge method, (b) Chemical Vapour Deposition (CVD), and (c) laser ablation method (Rafique & Iqbal, 2011). Importantly, multi-wall CNT is stiffer, cheaper and produced at a larger scale, therefore, it can be considered as an obvious choice over single wall CNT for modification of asphalt binder (Steyn, Bosman, Galle, & van Heerden, 2013).
Innovative tools for atrial fibrillation ablation
Published in Expert Review of Medical Devices, 2020
Laura Rottner, Daniela Waddell, Tina Lin, Andreas Metzner, Andreas Rillig
Over the last decade, ablation devices have already undergone technical improvements, aiming for better lesion durability, shorter procedure times and fluoroscopy dosages as well as improved safety, and clinical results. Radiofrequency-based PVI in combination with a 3D-mapping system was considered the ‘gold standard’ for a long time. Contact-force (CF) catheters and the introduction of individualized ablation protocols promise to overcome limitations of single-tip RF-based ablation by facilitating sufficient lesion formation. Nevertheless, balloon-based PVI, in particular cryoballoon (CB) – based ablation, has emerged as the most common alternative ablation tool for the treatment of AF, especially paroxysmal AF. As a ‘singe-shot’ ablation modality and therefore not only readily applicable and easy to learn, but also – because of its ‘over-the-wire’ strategy – is a very safe tool, resulting in a low incidence of perforation and pericardial effusion or tamponade. Beyond, RF balloon technologies promise beneficial patient´s outcome and a favorable safety profile due to the possibility of energy titration during PVI. Moreover, new mapping technologies to identify non-PV-triggers were demonstrated to be helpful obtaining SR in patients with persistent or long-standing persistent AF as well as preventing arrhythmia recurrence after previous PVI and may have the potential to enable real-time therapy assessment during ablation procedure.