Dentifrice Rheology
Laba Dennis in Rheological Proper ties of Cosmetics and Toiletries, 2017
All type 1 dentifrice today contain “hydrated silica.” This is a term devised for the purpose of ingredient labeling. Unfortunately, it is a very broad in physical-chemical concept and encompasses vastly different physical forms of silicon dioxide with different physical properties. The “hydrated silicas” in use in marketed toothpastes range from xerogels to pyrogenic silicas. Xerogels approach classical dental abrasives in particle size and inertness, and lack of ability to form a strong three-dimensional network in a lean solvent system. Pyrogenic silicas are very effective at forming a network. Silica aerogels and some silica precipitates have particle size, surface area, and pore volumes intermediate between those of xerogels, on one hand, and the finer pyrogenic and fumed silicas, on the other, and can readily form three-dimensional networks with aqueous glycerine and sorbitol and other ingredients, e.g., PEGs. One precipitated silica preparation available for type 1 dentifrices is prepared in such fashion as to provide a reproducible distribution of abrasive particles and particles able to form a structured lean solvent system. It is most convenient, however, to discuss the toothpastes situation in terms of an essentially inactive abrasive particle (xerogel) and finer, structure-forming particles such as aerogels, fine precipitates, and pyrogenic silicas.
Nutrients in Bamboo Shoots
Nirmala Chongtham, Madho Singh Bisht in Bamboo Shoot, 2020
Silicon (Si) is a non-metallic element and the second most abundant element in the Earth’s crust with a great affinity for oxygen, forming 92% silica and silicates. It is also the most abundantly available trace element after iron and zinc. Chemically, silica is an oxide of silicon, viz. silicon dioxide and is generally colourless to white and insoluble in water. When associated with metals or minerals the family of silicates is formed. Humans are exposed to numerous sources of silica/silicon including dust, food, pharmaceuticals, cosmetics and medical implants and devices. As a metalloid, silicon has been used in many industrial applications including use as an additive in the food and beverage industry. As a result, humans are exposed to silicon through both environmental exposures and also as a dietary component. Bamboo extract is the richest known source of natural silica, containing over 70% organic silica. This is more than 10 times the level found in the widely used Horsetail plant (Equisetum) that contains 5% to 7% silica.
Advanced Biotechnology
Lawrence S. Chan, William C. Tang in Engineering-Medicine, 2019
Silicon oxide is the sacrificial material of choice for polysilicon or SOI surface micromachining. It can be grown or deposited by a number of means. Exposure of silicon surfaces at high temperatures (1000°C and higher) in oxygen grows high-quality silicon dioxide films. This thermal oxidation process is common in the IC industry, and thus is well characterized and highly reproducible. However, the oxide film expands in volume by about 45% while consuming the adjacent silicon material, thus it creates a compressive stress in the silicon parts. Alternatively, oxide films can be deposited by LPCVD using the pyrolytic reaction of silane and oxygen at a pressure of 300–500 mT and a temperature of 450°C. Because of the substantially lower temperature of deposition compared to oxidation, LPCVD oxides are commonly called low-temperature oxides (LTO).
Application of liquisolid technology for promoting the renoprotective efficacy of walnut extracts in chronic renal failure rat model
Published in Drug Development and Industrial Pharmacy, 2019
Sahar Youssef Al-Okbi, Doha Abdou Mohamed, Thanaa El-Sayed Hamed, Sameh Hosam Abd El-Alim, Ahmed Alaa Kassem, Dina Mahmoud Mostafa
An essential step in the production of a successful liquisolid system is the estimation of the flow characteristics of the powder excepients and the liquid powder mixtures [54]. A powder can only retain a certain amount of liquid while still keeping adequate flow properties [32]. Results for the determination of the angle of slide are presented in Figure 1. The flowable liquid retention potential (ΦCarrier) for MCC in PEG 400 was 0.815 corresponding to an angle of slide of 33° while in Tween 20 it was 0.2, with an angle of slide of 28.75°. For silicon dioxide, the liquid retention potential (ΦCoat) in PEG 400 was 0.2 possessing an angle of slide of 25.2° and in case of Tween 20, it was 0.2 corresponding to an angle of slide of 30.33°. It was noticed that in some liquid/powder admixtures, all corresponding angles were less than 33°, so the highest angle was selected to represent the optimum flowability [55]. It was previously reported that if the angle of slide 33° is not reachable, the angle closest to 33° is selected [34].
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
The XRD pattern of AD-AgNPs, AD-AgNO3, AD-PE, and AD-control are presented in Figure 3. The peaks observed at 38.17°, 44.37°, and 64.58° correspond to (111), (200), (222) and (220) reflection planes of a face-centred cubic structure (fcc) of silver (ICDD database), respectively (Li J et al. 2020). Furthermore, the peaks observed at 25.57°, 35.16°, 38.21°, 44.43°, 52.54°, 57.45°, 61.27°, 64.45°, 68.10°, 77.17°, 80.76°, 84.32°, 86.40°, and 88.96° correspond to (012), (104), (110), (113), (024), (116), (112), (214), (300), (119), (220), (223), and (0210) reflection planes of a fcc aluminium oxide (ICDD database), respectively. The inter-planar spacing (dcal) values of AD-AgNPs were 2.35, 2.03, 1.60, and 1.44 Å compared with standard silver, and 3.48, 2.55, 2.35, 2.03, 1.74, 1.60, 1.51, 1.44, 1.37, 1.23, 1.18, 1.14, 1.12, and 1.10 Å for Al2O3 compared with standard aluminium oxide. Additionally, the peaks around 25.56°, 35.16°, 37.84°, and 43.30° are due to the presence of silicon oxide (Il’ves et al. 2015). The diffraction peaks at 25.56° and 80.64° correspond to (012 and 220) plan which indexed to fcc for α-Al2O3 and γ-Al2O3, respectively, a metastable phase of alumina (Papi et al. 2015; Ismail et al. 2017). The silver peaks in the XRD pattern significantly support the formation of nano-sized particles over the alumina discs (Valsalam et al. 2019). The average crystallite size of silver nanoparticles was calculated to be between 64.56 nm and 78.08 nm.
Silicon dioxide nanoparticle exposure affects small intestine function in an in vitro model
Published in Nanotoxicology, 2018
Zhongyuan Guo, Nicole J. Martucci, Yizhong Liu, Eusoo Yoo, Elad Tako, Gretchen J. Mahler
Food-grade silicon dioxide (SiO2) or amorphous silica (coded E551) has been found to contain particles in the nano-size range (at least one dimension less than 100 nanometers) (Auffan et al. 2009; Dekkers et al. 2011; Peters et al. 2012; Yang et al. 2016). Similar to TiO2 NP, SiO2 nanoparticles (NP) are used to improve the taste and texture of rich foods without adding calories, preserve food color and durability, and carry fragrances or flavors (Dekkers et al. 2011; Contado et al. 2016). SiO2 NP also act as anti-caking agents to maintain flow properties of powdered mixes, seasonings, and coffee whiteners (Dekkers et al. 2011; Contado et al. 2016). The use of nanomaterials in food production and pharmaceutics, however, may have unknown health effects due to unexpected biological interactions (Dekkers et al. 2011).
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