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Ultratrace Minerals
Published in Luke R. Bucci, Nutrition Applied to Injury Rehabilitation and Sports Medicine, 2020
Animal studies with silatranes (synthetic organic silicon compounds) have found preliminary suggestions of enhancement of wound healing, but data on humans are lacking.1083–1085 No literature has reported on silicon supplementation for human connective tissue disorders, but Ayurvedic and Chinese herbal medicine texts describe the use of Tabashir (joints of specific female bamboo plants very rich in silicates) for bone pains. This was apparently due to the similarity in appearance between joints in bamboo stalks and the human spine. Thus, there is no research on the effects of silicon for disorders of cartilage or bone tissues. Further research into the therapeutic effects of silicates in humans with osteoarthritis and osteoporosis seems worthy of attention.
Organo-Modified Siloxane Polymers for Conditioning Skin and Hair
Published in Randy Schueller, Perry Romanowski, Conditioning Agents for Hair and Skin, 2020
The basic raw material from which silicones are formed is quartz, i.e., silica or silicon dioxide (SiCh). In the form of crystals or fine grains, quartz is the main constituent of white sand. In 1824, Jons-Jacob Berzelius, a Swedish chemist, was successful in liberating elemental silicon (Si) from quartz by reduction of potassium fluorosilicate with potassium. Alkylation of elemental silicon to prepare alkyl silanes was done initially by Friedel and Crafts (1863) using zinc compounds, by Kipping (1904) using organo-magnesium compounds (Grignard reaction), and independently in the 1930s by Hyde (Corning Glass Works) and Rochow (General Electric) using methyl chloride. These scientists synthesized the silicon-carbon bond—one of the most important steps in the history of organo-siloxane polymer development (1,2). The silicon-oxygen-silicon backbone was synthesized by Ladenburg in 1871 by hydrolyzing diethyldiethoxysilane in the presence of a dilute acid to form an oil (silicone). Between 1899 and 1944, Kipping published 54 papers on the subject of silicon chemistry, describing the first systematic study in the field. This work helped Hyde and Rochow develop a commercial process—"the direct process"— using elemental silicon and methyl chloride to produce organo-silicon compounds. Current reviews of the synthesis of organo-siloxane polymers have been written by Colas (3) and Rhone Poulenc (4).
Boron, Manganese, Molybdenum, Nickel, Silicon and Vanadium
Published in Judy A. Driskell, Ira Wolinsky, Sports Nutrition, 2005
Ingested silicon has a relatively low order of toxicity. About the only pathological condition that may occur with a high intake of silicon is urolithiasis. Most silicon compounds, especially silicon dioxide compounds, are essentially nontoxic to humans when taken orally. Magnesium trisilicate, an over-the-counter antacid, has been used by humans for more than 40 years with only minimal apparent deleterious effects reported. In addition to urolithiasis, a high intake of silicon may interfere with the absorption or utilization of some essential nutrient, particularly zinc. An antagonism between zinc and silicon results in high dietary silicon’s decreasing the zinc concentrations in plasma and tissues of rats.166,167 The amount of dietary silicon used to show the antagonism was extremely high in one study;167 the rats were fed 400 mg Si/kg body weight as sodium metasilicate in drinking water for the last 6 weeks of an 18-week experiment. In the other study,166 the effect of a 270-mg Si/kg diet as tetraethylorthosilicate on decreasing plasma zinc was significant only in zinc-deficient rats.
E-cigarette vaping associated acute lung injury (EVALI): state of science and future research needs
Published in Critical Reviews in Toxicology, 2022
Antonella Marrocco, Dilpreet Singh, David C. Christiani, Philip Demokritou
While to date many efforts have been made to characterize physicochemically and toxicologically the nicotine-based e-cig vapors (Williams et al. 2013; Zhao et al. 2016; Zhao, Nelson, et al. 2018; Zhao, Zhang, et al. 2018; Hwang et al. 2020; Lee and Christiani 2020), the literature regarding vapors emitted from THC/VEA-based e-liquids is very scarce, making it difficult for health risk assessors to perform risk assessment evaluations. To date, the majority of published studies focus on the physicochemical characterization (Meehan-Atrash et al. 2019; Duffy et al. 2020; Jiang et al. 2020; Lanzarotta et al. 2020; Mikheev et al. 2020; Muthumalage, Friedman, et al. 2020; Wagner et al. 2020; Ciolino, Falconer, et al. 2021; Ciolino, Ranieri, et al. 2021; Duffy et al. 2021; Gonzalez-Jimenez et al. 2021; Guo et al. 2021; Kovach et al. 2021; Lu et al. 2021; Lynch et al. 2021; Brosius et al. 2022; Marrocco et al. 2022; McGuigan et al. 2022; Mikheev and Ivanov 2022) or biological in vivo/in vitro assessment (Muthumalage and Rahman 2019; Bhat et al. 2020; Jiang et al. 2020; Matsumoto et al. 2020; Muthumalage, Lucas, et al. 2020a; Marrocco et al. 2022; Matsumoto et al. 2022) of e-liquids or vapors generated from a single e-liquid compound (i.e. THC or VEA or other additives). Despite the paucity of data, many lung irritants and toxicant chemicals have been identified in the vaping emissions, which can play crucial roles in the development of EVALI, such as carbonyls, alkyl alcohols, esters, carboxylic acids, short-chain alkanes, silicon compounds, hydrocarbons, volatile organic compounds (VOC), terpenes, reactive oxygen species (ROS) and heavy metals, which have been found to exert varying degrees of cytotoxicity, alveolar epithelial damage and lung inflammation both in vivo and in vitro.
Preparation and characterisation of flame retardant encapsulated with functionalised silica-based shell
Published in Journal of Microencapsulation, 2018
Doan-Trang Hoang, Diane Schorr, Véronic Landry, Pierre Blanchet, Stéphanie Vanslambrouck, Christian Dagenais
It was found that the most significant difference between APP before and after encapsulation was their residual weight at the end of the TGA experiments. As described in the literature (Yu et al.2003, Qian et al.2014), the char layer could slow down heat and mass transfer between the gases and condensed phases, hence, an effective protection of the char layer enables to improve the flame retardant performance during combustion. Therefore, the residue corresponding to the char played an important role in the TGA analysis. The increased residue amounts of encapsulated APP could be explained by the synergistic effect of silicon with phosphorus and nitrogen of APP. The silicon compounds migrated to the char surface and enhanced the char layer during the thermal degradation. Besides, visual observation of the residues in the crucible at the end of the TGA measurement showed white colour for APP (Figure 6(a)), whereas a grey residue was obtained for MAPP-2 (Figure 6(b)). The white residue could be explained by the formation of inorganic compounds as APP sample is carbon-free. Meanwhile, it was demonstrated that the thermal degradation of polysiloxane in air forms white silica powder and black silicon-oxycarbide (Belva et al.2006). Therefore, the grey residue of MAPP-2 could be attributed to the presence of carbon from CH3 of organic precursor MTES on sample. It could also suggest that the interaction between APP and polysiloxane shell occurred and their decomposition products promoted the formation of char (Deng et al.2014). The presence of carbon in MAPP-2 residue was confirmed by XPS survey analysis (Figure 6(c)). As expected from the MAPP-2 residue structure, the silicon (10.40%) and carbon (1.17%) attributed to polysiloxane degradation were detected. The appearance of phosphorus (12.19%) and nitrogen (0.42%) belonged to the APP core detected after the thermal decomposition of polysiloxane shell. These results indicated that coating APP surface by organic-inorganic hybrid silica-based compound enhanced the char yields, which offer a better protection of the substrate from the thermal degradation.