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Application of Synchrotron Radiation Technology in Marine Biochemistry and Food Science Studies
Published in Se-Kwon Kim, Marine Biochemistry, 2023
Toshiki Nakano, Masafumi Hidaka
CaCO3 crystals include aragonite, calcite, and vaterite. More than 95% of otoliths are composed of aragonite crystals of CaCO3. In addition to Ca, over 30 elements, including sodium (Na), potassium (K), strontium (Sr), zinc (Zn), phosphorus (P), manganese (Mn), magnesium (Mg), silicon (Si), and iron (Fe), are present in otoliths at extremely low concentrations. However, the mechanism of trace element accumulation in otoliths remains unclear. Organic substances, such as glycoproteins, are present in otoliths (Thomas and Swearer 2019; Katayama 2021; Campana and Thorrold 2001; Otake 2010; Campana 1999). The construction of CaCO3 in otoliths is regulated by enzymes. Therefore, the formation of otoliths occurs via biomineralization and may play an important role in governing otolith chemical patterns and element incorporation (Hüssy et al. 2020; Cook et al. 2018).
Issues in Fisheries and Aquaculture
Published in Joyce D’Silva, John Webster, The Meat Crisis, 2017
The effect of global warming on fisheries should have a chapter in its own right. There are two known ways global warming affects fish. The first concern is the effect of raising water temperatures. Some fish populations may benefit, whilst others are damaged or relocate to cooler seas. A particular current concern is the death of coral reefs, which indicates how susceptible some marine ecosystems are to relatively small changes in the environment. Second, the oceans are acidifying as the level of dissolved CO2 rises. If current trends continue, the pH of ocean water is predicted to fall from a preindustrial pH of 8.2 to pH 7.8 by 2100 (Caldeira and Wickett 2005). This, in biological terms, is a huge drop and how life forms will cope is not known. However, as the pH of seawater falls, so animals with calcified shells find it increasingly difficult (they need more energy) to secrete aragonite and calcite, the calcium constituents of their shells. Shellfish are therefore expected to be amongst the worst affected (Orr et al. 2005).
Biomedical Applications of Raman Scattering
Published in R. Michael Gendreau, Spectroscopy in the Biomedical Sciences, 1986
An obvious difficulty with biological samples is microscopic heterogeneity. The normal spot size of a focused laser beam is about 0.1 mm, which would yield Raman spectra averaged over a diverse variety of structural elements. The coupling of a microscope and an image intensifier with a Raman spectrometer permits the examination of biological materials in situ and provides a solution to this problem. Microscope objectives produce a 1-μm spot on a sample with a depth of focus of 5 μm. Spatial resolution to this level may therefore be achieved, assuming proper design of the Raman optical system. To prevent sample degradation during the long exposure time when spectra are recorded using a monochromator and single photomultiplier, the latter is replaced by a multichannel detector. This approach, pioneered by Delhaye and co-workers in France,30,31 can yield a two-dimensional “image” of an object according to the Raman spectrum of its constituents. The potential of a nondestructive method, which combines chemical identification of a structure with physical location in a complex environment is clear. Although biomedical applications of the method are scarce, Buiteveld et al.32 have examined microscopic particles in human lung tissue. Paraffinized unstained sections were deposited on microscope slides and 5145 Å radiation from an Argon ion laser was focused to diameters of laser spots ranging from 1.6 to 4 μm. Particles of CaCO3 (calcite) were unambiguously identified in the tissue.
Scylla Sp. Shell: a potential green adsorbent for wastewater treatment
Published in Toxin Reviews, 2022
Azrul Nurfaiz Mohd Faizal, Nicky Rahmana Putra, Muhammad Abbas Ahmad Zaini
Crab shell is rich in calcium carbonate. Two polymorphs of calcium carbonate, namely calcite (a trigonal shape) and aragonite (an orthorhombic shape) are present with similar crystal structure and thermodynamic stability (Van et al.2019). Calcite is the primary constituent of shells of marine organism while aragonite forms naturally in almost all mollusk shells (Du et al.2011). Van et al. (2019) and Lin et al. (2020) recognized the roles of calcite and aragonite as active sites for ion-exchange with divalent metal ions, Pb2+ and Cd2+. When calcite and aragonite are in contact with water, the calcareous layer in crab shell dissolves to release Ca2+ and CO32- ions into the solution (Zhou et al.2017; Van et al.2019). The Ca2+ ions interchange with cations in bulk solution, while CO32- ions form solid-solution nuclei (Van et al.2019). On the other hand, the increase of solution temperature encourages the dissolution of calcite and aragonite to release bicarbonate anions. Consequently, the interactions with cations lead to the precipitation of metal carbonate on the adsorbent surface (Sdiri et al.2012, Van et al.2019). Du et al. (2011), Van et al. (2019) and Pap et al. (2020) suggested that the adsorption mechanisms of heavy metals by crab shell adsorbent are primarily due to ion-exchange and surface complexation at low concentration, and dissolution-precipitation at high concentration.
Modified self-healing cementitious materials based on epoxy and calcium nitrate microencapsulation
Published in Journal of Microencapsulation, 2021
Fahimeh Farshi Azhar, Aylin Ahmadinia, Alireza Mohammadjafari Sadeghi
For self-healing of concrete, other core materials, such as sodium silicate, calcium nitrate, water, etc., have been used based on specific healing mechanisms, i.e. hydration or recrystallization due to chemical reaction between minerals in concrete and encapsulated healants (Huang et al.2011, Mostavi et al.2015). Calcium nitrate, because of its low cost and capability to accelerate the setting of unhydrated cement, was recently investigated (Al-Ansari et al.2017). When a crack is created, at its surface and in the presence of moisture, calcium nitrate would react with unhydrated cement particles to form hydroxy nitrate salts that increase the densification of cement and contribute to the formation of calcium silicate hydrate. Also, it would also react directly with the cementitious matrix in the presence of moisture to create calcium hydroxide and calcium carbonate, where the latter is made by increasing the saturation index of calcite (Arce et al.2017, Milla et al. 2019, Hassan et al. 2016).
Assessment of an anti-scale low-frequency electromagnetic field device on drinking water biofilms
Published in Biofouling, 2018
F. Gosselin, L. Mathieu, J.-C. Block, C. Carteret, H. Muhr, F. P. A. Jorand
In order to know whether EMF treatment had any effect on CaCO3 crystallization, the precipitates formed on the surface of coupons exposed to oversaturated water, with or without exposure to the EMF were analysed. Aragonite was the primary CaCO3 polymorph found on coupons exposed to the EMF, whereas calcite was dominant on the control (no EMF). Calcite and aragonite were identified from Raman spectroscopy by major peaks specific to aragonite at 205 cm−1 and 152 cm−1, and by a peak at 281 cm−1 specific to calcite (De La Pierre et al., 2014) (Figure 2). The peak for calcite was relatively higher in intensity in the Control than in the Assay when curative or preventive EMF treatments were applied. Moreover, crystal morphologies were in accordance with aragonite and calcite as showed by SEM (Figure S3). Consequently, surfaces in contact with water exposed to the EMF contribute to the deposition of aragonite at the expense of calcite.