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Organic Phase Change Materials
Published in Asit Baran Samui, Smart Polymers, 2022
Swati Sundararajan, Asit Baran Samui
Diatomite or diatomaceous earth is a natural amorphous silicate possessing high porosity, excellent absorption capacity, chemical stability, and is of low cost.102 This lightweight building material can be integrated with a maximum of 50 wt% PEG to prepare shape-stabilized PCMs. The addition of EG improves the heat transfer rate of the PEG/diatomite composites. The wallboards fabricated with composite PCM, exhibit a temperature difference of 2.3°C on the inner surface.
The Indian Scenario
Published in Ranadhir Mukhopadhyay, Victor J. Loveson, Sridhar D. Iyer, P.K. Sudarsan, Blue Economy of the Indian Ocean, 2020
Ranadhir Mukhopadhyay, Victor J. Loveson, Sridhar D. Iyer, P.K. Sudarsan
The discovery of the sponge-derived nucleosides spongothymidine and spon-gouridine was made by Bergmann and Feeney (1951). Subsequently thousands of marine natural products (MNP) from marine organisms have been reported, extracted, and patented. This has led to the emerging field of marine biotechnology that has found favor with the pharmaceutical industry (Libes, 2009). For example, diatomaceous earth is used as an insecticide, as a filtration medium, and as an abrasive. Varieties of seaweeds are used to treat dropsy, menstrual difficulties, gastrointestinal disorders, abscesses, and cancer; while sponges have been used to treat tumors, goiter, dysentery, diarrhea, stanching of blood flow, and as contraceptives.
Filtration Powders and Diatomaceous Earths
Published in Willy J. Masschelein, Unit Processes in Drinking Water Treatment, 2020
Diatomaceous earth, diatomite, and even Kieselguhr are fossilized rocks consisting of dead diatomaceae occurring in most clay or lime deposits. To render their exploitation profitable, the deposits must be of sufficient purity and the geological formations of sufficient thickness.
Alterations of physical properties and microstructure of marine diatomite owing to variation of diatom content
Published in Marine Georesources & Geotechnology, 2023
Yiqing Xu, Xianwei Zhang, Xinyu Liu, Gang Wang
Fossilised diatoms formed from the remains of unicellular microalgae are widely distributed in marine deposits (Liao et al. 2003; Xu et al. 2011), and geological processes such as volcanic activity and weathering make diatom frustules (DFs) an important component of natural clayey soils (Verdugo 2008), which are referred to as diatomite or diatomaceous earth (Shiwakoti et al. 2002). Diatomite is frequently used in industrial materials, including filter aids (Galán et al. 1993), attrition-resistant material additives (Van Garderen et al. 2011), and nanocomposite materials (Deng et al. 2019). Numerous studies of natural diatomite have revealed that it usually has distinct properties which are due to the presence of DFs (Day 1995; Hong, Tateishi, and Han 2006). The characteristics of diatomite include strong water retention (Díaz-Rodríguez et al. 1998), high compressibility (Locat and Lefebvre 1985; Ovalle and Arenaldi 2021), and high shear strength (Evans and Moug 2020), which are unique and cannot be described by the classical formulas established for sands or clays (Arenaldi, Ovalle, and Barrios 2019); this makes the soil classification of diatomite especially difficult (Locat and Tanaka 2001; Jang and Santamarina 2016).
Insecticidal effects of two Tunisian diatomaceous earth loaded with Thymus capitatus (L.) Hoffmans and Links as an ecofriendly approach for stored coleopteran pest control
Published in International Journal of Environmental Health Research, 2023
Olfa Bachrouch, Houwaida Nefzi, Souhir Belloumi, Karima Horchani-Naifer, Jazia Sriti Eljazi, Soumaya Haoual Hamdi, Kamel Msaada, Jalel Labidi, Manef Abderrabba, Jouda Mediouni Ben Jemaa
Diatomaceous earth (SiO2·nH2O) is a rock of biogenetic origin. It is considered like a pale sedimentary rock composed of an important quantity of silica SiO2 and low quantities of minerals components according to the clay impurities. So, DEs is considered as an efficient natural dust and acts as a desiccant against pests (Liška et al. 2017).
PEI-modified diatomite/chitosan composites as bone tissue engineering scaffold for sustained release of BMP-2
Published in Journal of Biomaterials Science, Polymer Edition, 2021
Xiangyu Wang, Yufang Li, Wenjuan Ren, Ruxia Hou, Haifeng Liu, Ran Li, Shouji Du, Lu Wang, Junyu Liu
Diatomite, also known as diatomaceous earth (DE), is an inexpensive fossil compound formed by the fragments of diatom siliceous skeletons at the bottom of lakes or oceans over millions of years. It has similar physicochemical properties as the fabricated silica nanoparticles [8, 9]. The DE micro shells, characterized by unique pill-box microstructures, possess porosity in the micro/nanoscale range, high surface area, superior biocompatibility and surface hydroxyl groups. Thus, these shells represent a promising, abundant and low-cost biomaterial for drug delivery applications [10, 11]. On the other hand, the drug delivery capacity in the target area, which can result in a high local concentration with few side effects, is an important evaluation index for the local delivery systems. Bone morphogenetic protein-2 (BMP-2), which has been approved by the US Food and Drug Administration (FDA) for several orthopedic diseases since 2002 [12], is a growth factor with an obvious osteogenic effect. However, the clinical results involving BMP-2 are not always ideal. For instance, the osteogenic effect of low dose BMP-2 is not optimal [13]. Besides, the allergic dosage can cause a series of side effects [14–16]. Therefore, controlling the dose of BMP-2 and improving its curative effect are of high importance. In fact, in some cases, the protein is incorporated in the material by incubation, and the initial burst release appears subsequently, unless the material–protein interaction occurs [17]. Therefore, an appropriate protein adsorption method is required to obtain an enhanced drug load capacity and slow protein release. Currently, the common methods to improve the protein adsorption are based on enhancing the specific surface area [18] and surface functionalization approach [19, 20]. The bare DE surface exhibits highly negative charges due to the presence of hydroxyl groups (–OH), thus, promoting the cationic adsorption. However, the scaffolds with negative surface charges are not conducive for the adhesion of BMP-2 due to the net negative charge of BMP-2 [21]. Thus, it is important to modify the DE surface with positively charged surfactants or chemical moieties. As a cationic polyelectrolyte, polyethyleneimine (PEI) has been widely used for the modification of biochars, nanoparticles, extracellular vesicles, liposomes, etc., so as to improve their delivery efficiency [22–25]. PEI molecules of lower molecular weight are also efficient reagents with much lower cytotoxicity [26]. After treatment with PEI, the surface charge of the modified diatomite (MDE) turns positive, and the BMP-2 molecules can be effectively adsorbed on the diatomite surface through electrostatic attraction. Furthermore, many literature studies have reported that the surface potential of scaffold affects the cell morphology and density during cell adhesion and proliferation [27, 28]. As a consequence, the modification of DE by PEI is beneficial not only for protein adsorption, but also for improving the biocompatibility of the material.