China
Africa
Explore chapters and articles related to this topic
Inhalation Toxicity of Metal Particles and Vapors
Published in Jacob Loke, Pathophysiology and Treatment of Inhalation Injuries, 2020
Calcium salts are considered nontoxic except at very high doses. Inhalation of moderately caustic calcium oxide or hydroxide causes chemical pneumonia and severe irritation of the upper respiratory tract. In humans, inhalation of calcium cyanamide causes transient vasomotor disturbances of the upper portion of the body; higher doses cause dermatitis, permanent vasomotor changes, and dyspnea (DeLarrad and Lazarini, 1954).
Dentin-Pulp Complex Regeneration
Published in Vincenzo Guarino, Marco Antonio Alvarez-Pérez, Current Advances in Oral and Craniofacial Tissue Engineering, 2020
Amaury Pozos-Guillén, Héctor Flores
Another type of apexification named ‘apical MTA plug’ was described using Mineral Trioxide Aggregate (MTA). MTA is a repair material made of fine hydrophilic particles of tri/dicalcium silicate, tricalcium aluminate, tricalcium oxide and silicate oxide (Parirokh and Torabinejad 2010). MTA is placed into the root canal space and acts as a mechanical barrier to prevent coronal leakage and penetration of microorganisms. Some disadvantages of this material are difficulty to manipulate, the possibility of tooth discoloration and difficulty to remove from the root canal However, neither calcium hydroxide nor MTA barrier technique allow further root growth in length, maturation of the apex or root wall thickening. New calcium silicate-based materials have recently been developed with the purpose of improving clinical use and overcoming MTA limits BiodentineTM is a bioceramic made of tricalcium silicate, dicalcium silicate, zirconium oxide, calcium carbonate, calcium oxide and iron oxide. It is mixed with a hydrosoluble polymer and calcium chloride to decrease the setting time (Rajasekharan et al. 2014). This biomaterial has shown reduced setting time with interesting physical and biological properties as a dentine restorative material (Koubi et al. 2013; Topçuoglu and Topçuoğlu 2016).
Bio-Ceramics for Tissue Engineering
Published in Naznin Sultana, Sanchita Bandyopadhyay-Ghosh, Chin Fhong Soon, Tissue Engineering Strategies for Organ Regeneration, 2020
Hasan Zuhudi Abdullah, Te Chuan Lee, Maizlinda Izwana Idris, Mohamad Ali Selimin
There are several types of bioactive glasses (BG) and these include silicate based-glasses, phosphate based-glasses and borate based – glasses (Jones 2015, Rahaman et al. 2011). Miguez-Pacheco et al. (2015) listed (Table 8.3) the formulations of several bioactive glasses (BG) which have been recently studied and investigated thoroughly (Jones 2015, Rahaman et al. 2011, Nandi et al. 2011, Hench 1998, Brink et al. 1997, Brown et al. 2008, Lindfors et al. 2010, Clare 2004, Detsch et al. 2014, Filgueiras et al. 1993). It can be seen that bioactive silicate-based glasses have been found to be a revolutionary material after trials, showing effective and successful adherence and bonding to human bone and tissue. Hench et al. (Hench et al. 1971, Hench 2006, 2015) designed Bioglass 45S5 with 45 wt. % silica (SiO2), 24.5 wt. % calcium oxide (CaO), 24.5 wt. % sodium oxide (Na2O) and 6 wt. % phosphorus pentoxide (P2O5) as shown in Fig. 8.8. These chemical combinations are categorized as Class A bioactivity owing to their outstanding osteoconductive and osteoproductive characteristics (Hench 2015). This is due to the ions released from BG reacted positively in biological solutions such as in simulated body fluid (SBF) and thus induced the formation of carbonated hydroxyapatite (HCA) layers on the surface of glass (Rezwan et al. 2006, Hoppe et al. 2011).
Mortality and physiological impacts of the tea saponin against Ephestia kuehniella Zeller (Lepidoptera: Pyralidae)
Published in Toxin Reviews, 2022
Morteza Shahriari, Arash Zibaee, Seyyedeh Kimia Mirhaghparast, Sarah Aghaeepour Pour, Samar Ramzi, Hassan Hoda
Tea saponin was extracted based on the procedure of Li et al. (2012). C. sinensis seeds were collected from Langroud tea gardens (Guilan Province, Northern Iran), powdered, and sifted. The powder was stirred in warm water (liquid to the solid ratio: 6:1; the water temperature: 80 °C; soaking time 6 h). Then, the samples were centrifuged at 5000 rpm, for 30 min at 25 °C to obtain the primary extracted solution. The concentration of 30% of flocculant of polyaluminum chloride was added into the content of 1% of the primary extracted liquid by weight and kept at 25 °C for 2 h to remove impurities. Afterward, centrifugation was performed at 5000 rpm, at 25 °C for 30 min to get the demanded supernatant. Ten grams of calcium oxide as the settlement agent was added to the earlier supernatant and stirred for 4 h before being centrifuged at 5000 rpm for 30 min at 25 °C. The present supernatant was removed, and ammonium bicarbonate was added (30% of the total mixture) to remove calcium from the TS. The samples stirring for 2 h at 60 °C and centrifugated at 5000 rpm for 30 min at 25 °C. Afterward, tubes containing the samples were put in a boiling water bath for 5 min and incubated at 80 °C for 12 h within an oven to gain TS powder (75% purity).
Distribution and accumulation of heavy metals in Lake Manzala, Egypt
Published in Egyptian Journal of Basic and Applied Sciences, 2021
The study was carried out on Lake Manzala through summer, 2019, to monitor and evaluate the levels of some heavy metals and major oxides in water and sediments. Ten samples of both water and superficial bottom sediments have been collected. The sample sites have been chosen to cover sources of pollution near to discharges of most drains which consider the main source of pollution of the study area. Every one of the safeguards happened to limit dangers of the test tainting were followed during the assortment and treatment of tests. These samples have been chemically analyzed for the determination of their major oxides (Silica oxide SiO2, Aluminum oxide Al2O3, Ferric oxide Fe2O3, Magnesium oxide MgO, Calcium oxide CaO, Sodium oxide Na2O and Potassium oxide K2O) and a few heavy metals (Cu, Zn, and Pb, Fe, Mn and Cd). The study used the standard of the American Public Health Association (APHA) [11] for the collection, preservation and digestion technique. Heavy metals concentrations were measured using a graphite furnace atomic absorption spectrometer (Buck Scientific Company, USA) after the digestion technique. Calibration standards and quality control samples have been prepared freshly daily. The reference standard materials used to assess the precision and accuracy of the procedure. The study used analytical grade chemicals of certified standard solutions for the aim of sample preparation and its analysis.
Recent Advances in Biomaterials for the Treatment of Bone Defects
Published in Organogenesis, 2020
Le-Yi Zhang, Qing Bi, Chen Zhao, Jin-Yang Chen, Mao-Hua Cai, Xiao-Yi Chen
To enhance bone formation, mechanical strength, and the functional performance of large bone defects, Oryan et al. assessed the regenerative potential of Ca2+ silicate biomaterials produced by reacting calcium oxide and silica in various ratios in combination with the linear polysaccharide chitosan.63 The bilaterally implanted Ca2+ silicate bio-implants greatly improved radial bone healing and growth. Lui et al. similarly produced bioactive tetracalcium phosphate/magnesium phosphate composite bone cements that enhanced bone repair.51 Importantly, these materials were biodegradable. In alternative approaches, Munoz and colleagues demonstrated that non-setting injectable biomaterials loaded with ceramic particles enhance the stability of bone screws.64 These materials were unique as they permitted screw augmentation without impairing or favoring bone formation in a particular direction around the screw. This approach is principally advantageous for treating osteoporotic fractures that require screw stabilization.