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Sediments
Published in Michael J. Kennish, Ecology of Estuaries Physical and Chemical Aspects, 2019
Clays, silts, sands, and organic matter comprise most of the sedimentary particles in estuaries. The composition of clay minerals -— illite, kaolinite, and montmorillonite — is primarily a function of the type of source rock and climatic conditions. Quartz, SiO2, constitutes most of the coarse sediment fraction. Calcium carbonate formed from in situ biogenic processes is locally important in reefs or bioherms.
Rheological Additives
Published in Laba Dennis, Rheological Proper ties of Cosmetics and Toiletries, 2017
Bentonites contain 90% montmorillonite; other clays may be present, including kaolinite and illite. Bentonites can contain up to 10% nonclay minerals, such as zeolite (43). Montmorillonite platelets are larger than hectorites, which accounts for the lower swelling and thickening efficiency of bentonite. In practice, the montmorillonite dioctahedral smectites are often referred to as bentonite clays.
Radionuclide Concentrations in Soils lution-Processed Organic Solar Cells
Published in Michael Pöschl, Leo M. L. Nollet, Radionuclide Concentrations in Food and the Environment, 2006
Radionuclides can be absorbed by some mineral fractions of the soil (silt and clay fractions). The main minerals in these fractions are smectite, illite, vermiculite, chlorite, allophone, and imogolite. Other contributors to the absorption process are the oxides and hydroxides of silica, aluminum, iron, and manganese. Soils with a high content of illite, smectite, vermiculite, or mica within the clay fraction absorb large amounts of cations due to their intrinsic negative charge [1]. On the other hand, anions can be absorbed by aluminum and iron oxides at pH values in the range of 8 to 9. Water-soluble anionic compounds such as phosphate, selenite, molybdate, and arsenate can be absorbed by the formation of stable complexes and the exchange of ligands with aluminum and iron oxides. The presence of organic matter reduces anion absorption.
Microneedles for transdermal drug delivery using clay-based composites
Published in Expert Opinion on Drug Delivery, 2022
Farzaneh Sabbagh, Beom Soo Kim
Microneedles are known as useful tools for transdermal injection and delivery of cosmetics, drugs, and vaccines [50,51]. Pharmaceutical molecules pass through the skin layers in two stages of penetration and diffusion. The penetration step involves passage through the stratum corneum; the diffusion step proceeds to deeper tissues [52,53]. Some influencing factors, such as ionic strength, drug particle size, hydrogen bonding, and physicochemical properties can affect the transport rate and concentration of drugs [54,55]. The use of clay in the microneedle structure improves the bioavailability of the drug and the stiffness of the needle. By increasing the bioavailability of drugs, it is possible to increase resistance to degradation and extend the effectiveness of drugs in target tissues [56]. According to a recent study, the addition of 3 wt% clay led to the best possible improvement of microneedle mechanical properties [57]. When the clay concentration was increased to 5 wt%, the extra clay layer clustered, and microneedle mechanical properties decreased. Clay minerals are classified into three-layer types according to the arrangement and number of octahedral and tetrahedral sheets in their basic structures. Clays themselves can be classified into illite, chlorite, kaolinite, smectic (montmorillonite), halloysite, and vermiculite. Montmorillonite is the most important clay because of its high water absorption, high aspect surface area and ratio, good swelling capacity, remarkable intercalation properties, and high adsorption of heavy metals and organic molecules due to the natural inorganic layered nanostructure [58].
High-throughput tool to discriminate effects of NMs (Cu-NPs, Cu-nanowires, CuNO3, and Cu salt aged): transcriptomics in Enchytraeus crypticus
Published in Nanotoxicology, 2018
Susana I. L. Gomes, Carlos P. Roca, Natália Pegoraro, Tito Trindade, Janeck J. Scott-Fordsmand, Mónica J. B. Amorim
The test soil consisted of a natural soil collected at the Hygum site, Jutland, Denmark. In this site, the soil has been historically exposed to contamination with CuSO4 (due to activities of timber preservation, ceased more than 80 years ago), originating a well-known Cu gradient along the field, ranging from the natural background levels of 30 up to 2900 mg Cu/kg dry soil (Scott-Fordsmand, Weeks, and Hopkin 2000). Soil was sampled in the field to a depth of 20 cm, dried at 80 °C for 24 h in an oven (Memmert, Type UL40, Braunschweig, Germany) to exclude soil fauna, and then sieved through a 2 mm mesh to remove larger particles. The general physico-chemical characteristics of the soil are as follows: 20–32% coarse sand (>200 µm), 20–25% fine sand (63–200 µm), 11–20% coarse silt (20–63 µm), 12–20% silt (20–20 µm), 12–16% clay (<2 µm), 3.6–5.5% organic matter, Cation Exchange Capacity 6.8–10 (cmolc/kg dw), pH = 5, N 0.25–0.31% and P 0.10–0.12%. The clay mineralogy analyzed by X-ray diffraction was dominated by illite, kaolinite, chlorite, and vermiculite.
Innate/inflammatory bioregulation and clinical effectiveness of whole-body hyperthermia (balneotherapy) in elderly patients with osteoarthritis
Published in International Journal of Hyperthermia, 2018
Isabel Gálvez, Silvia Torres-Piles, Eduardo Ortega
The water of ‘El Raposo’ spa contains bicarbonate (396.5 mg/L) and calcium (130.2 mg/L) as predominant ions. The mineral-medicinal water fraction represents ∼40% of the mud. Mud’s solid content (∼60%) consists of a mixture of silt, clay and sand. It is basically composed of phyllosilicates (smectite and illite), quartz and calcite. The major chemical elements of the mud are SiO2, CaO, Al2O3 and Fe2O3 [24,25]. The predominant microalgae species present in the mud was identified morphologically as Monoraphidium pusillum (Spanish Bank of Algae).