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Reduction and Fixation of Sacroiliac joint Dislocation by the Combined Use of S1 Pedicle Screws and an Iliac Rod
Published in Kai-Uwe Lewandrowski, Donald L. Wise, Debra J. Trantolo, Michael J. Yaszemski, Augustus A. White, Advances in Spinal Fusion, 2003
Kai-Uwe Lewandrowski, Donald L. Wise, Debra J. Trantolo, Michael J. Yaszemski, Augustus A. White
Bone is composed of an organic collagenous tissue, mainly type I collagen, and an inorganic mineral phase, together forming a composite structure. The composition of the mineral phase varies between different parts of the bone and over time, but the main constituent of bone mineral is hydroxyapatite [Ca10(PO4)6(OH)2] [17]. Hydroxyapatite (HA) is a calcium phosphate ceramic. Ceramics are solid compounds of metals with nonmetals. When ceramic compounds are formed, generally a large amount of energy is released. These compounds are in a low energy state, meaning that further spontaneous reactions are unlikely to occur. Due to this, ceramics are the most chemically and biologically inert of all materials [18]. HA and tricalcium phosphate are not as inert as most other ceramics and tend to be less strong and more chemically reactive [18]. Calcium phosphate ceramics are highly biocompatible, and due to the chemical similarity to the natural bone mineral they are capable of forming a direct biochemical bond with bone [17]. The calcium phosphates of biological interest are calcium salts of ortophosphoric acid [19]. There are six principal calcium ortophosphates; dicalcium phosphate dihydrate, dicalcium phosphate anhydrous, octacalcium phosphate, (3-tricalcium phosphate, hydroxyapatite, and tetra-calcium phosphate monoxide. Out of these six compounds, the first three are too soluble to be used for biomaterials [19]. Many ionic substitutions may occur in HA, for example, the hydroxyl group may be replaced by fluoride, and the compound is then named fluorapatite. β-Tricalcium phosphate and HA are the most commonly investigated calcium phosphates. The term tricalcium phosphate is used for any pure calcium phosphate with a Ca/P atomic ratio of 1.50 [19]. The term does not imply either a composition or a structure. Tricalcium phosphate is a naturally occurring component of mineralized tissues. It is resorbed to a greater extent and more rapidly than HA [20]. In contrast to tricalcium phosphate, synthetic HA is not readily bioresorbable in appropriate forms, and it is therefore suitable for long-term clinical applications [17]. Due to these properties, HA has been more thoroughly investigated than other calcium phosphate materials. HA materials have been used in particulate forms, as pastes mixed with collagen or other materials, and also in dense solid or composite forms. The Ca/P atomic ratio of pure HA is 1.67. Several characteristics differ between bone apatite and the apatite of HA coatings. The HA in bone is more inhomogeneous with lack of crystal and chemical perfection, and it is also more reactive than HA coatings due to the large surface area of trabecular bone [21].
Construction of iron-mineralized black phosphorene nanosheet to combinate chemodynamic therapy and photothermal therapy
Published in Drug Delivery, 2022
Zhaoqing Shi, Jing Tang, Chuchu Lin, Ting Chen, Fan Zhang, Yuxing Huang, Ping Luan, Zhuo Xin, Qianqian Li, Lin Mei
We further performed XPS to study the surface composition of BPFe. P 2p scan of BPFe (Figure 2j) revealed the presence of P-O bond, a phosphorated form of P. Fe 2p scan of BPFe (Figure 2k) showed the presence of Fe2+ and Fe3+, and the atomic ratio between Fe2+ and Fe3+ was calculated as 1.67. Therefore, the Fe ions have mainly existed as iron (II) phosphates on the surface of BPNS. Thorough atomic ratio analysis of XPS was given in Table S1. Besides, the Fe to P mass ratio of BPFe was 1.041 determined by ICP-MS, which indicated that such in situ mineralization method could effectively load Fe ions. The prepared sample and optical absorption spectra were shown in Figure S1, and the linear relationship of BPFe between concentration and absorption was shown in Figure S2. All these results indicated that we successfully prepared BPFe by in situ mineralization. Moreover, we found that the BPFe had faster degradation under acidic pH of 6.0 than pH of 7.0 which indicated that the BPFe could respond to tumor acidic environment and degrade to release Fe ions (Figure S3).
Magnesium/silicon atomic weight percent ratio standards for the tissue identification of talc by scanning electron microscopy and energy dispersive X-ray analysis
Published in Ultrastructural Pathology, 2019
Sandra A. McDonald, Yuwei Fan, Rick A. Rogers, John J. Godleski
Identification of talc by SEM/EDS begins with its strong positivity under backscattered electron imaging (BEI), a technique where beam electrons are elastically deflected more than 90 degrees from their forward motion, and detected based on (among several possible modes) the presence of high atomic number elements in a sample.19 EDS spectral analysis of talc particles (using a spot quantitative mode) yields magnesium, oxygen and silicon peaks. Traces (EDS atomic weight % of <2%) of other elements such as Al, Ca, Na, K, and Fe may occasionally be present, given that small impurities may be present within mined talc, arise during manufacture processing, or contaminate talc samples at a subsequent stage. However, based on talc’s chemical formula, especially the stoichiometry of three Mg atoms to every four Si atoms, pure talc has a theoretical Mg/Si atomic ratio of 0.750 and atomic weight % ratio of 0.649.
A novel non-invasive strategy for low-level laser-induced cancer therapy by using new Ag/ZnO and Nd/ZnO functionalized reduced graphene oxide nanocomposites
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2018
Saeed Jafarirad, Ebrahim Hammami Torghabe, Seyed Hosseyn Rasta, Roya Salehi
Figure 5 revealed the EDX analysis of GO, ZnO/rGO, Ag-ZnO/rGO, and Nd-ZnO/rGO NCs. As it can be seen, the EDX pattern of GO shows two strong peaks of C and O elements, where because of the presence of functional groups containing oxygen on the GO surface, the ratio of O was more than C (Figure 8(a)). For ZnO/rGO NCs, the EDX pattern demonstrated a strong peak of Zn element with elements such as C and O (Figure 8(b)). Whereas significant peaks of Ag and Nd elements were observed in the EDX patterns of Ag-ZnO/rGO and Nd-ZnO/rGO NCs respectively (Figure 8(c,d)). Therefore, the presence of C, O, Zn, Ag and Nd elements in the structure of the NCs was confirmed from EDX studies. The atomic ratio of elements was quantitatively evaluated by EDX analysis and the results represented in tables of Figure 8.