Search Results (15)

In microbial electrochemical coupled treatment technology, the performance of electrodes critically affects the overall efficiency of wastewater treatment systems. Electrochemical electrodes in harsh wastewater often fail due to coupled organic fouling and corrosion. Herein, hierarchical ZnO–graphite composite films are developed as durable active interfaces. Fabricated via scalable spraying, the films feature coral-like architectures composed of ZnO nanoparticles interconnected by a conductive graphite network. Characterization confirms uniform elemental integration and preserved ZnO crystallinity. The films exhibit strong hydrophilicity, facilitating a stable hydration layer for effective underwater oleophobicity. Crucially, electrochemical tests in aggressive simulated landfill leachate demonstrate significant corrosion suppression and fouling resistance. Simultaneously, the embedded graphite phase ensures stable electrical conductivity (<5% variation) over prolonged immersion. This work establishes a robust interfacial design strategy for durable electrochemical sensors in complex wastewater environments. Full article

In the current context of environmental concerns and the search for sustainable food solutions, this study investigated the valorization of Luffa cylindrica seed press cake, a waste byproduct from oil extraction, as a functional ingredient for meat substitute formulations. The research systematically characterized the functional and bioactive properties of L. cylindrica seed press cake powder (LP) and its blends with tapioca flour (TF) at ratios of 30–70%. Techno-functional analyses included: hydration properties (water holding capacity, water absorption capacity, water absorption index, water solubility index, swelling power, oil absorption capacity); rheological characteristics; bioactive profiling through antioxidant assays (DPPH, ABTS, FRAP); and reducing sugar content determination. Meat substitute formulations were developed using an LP30/TF70 blend combined with coral lentils, red beet powder, and water, followed by a sensory evaluation and storage stability assessment. Pure L. cylindrica powder exhibited the highest water holding capacity (3.62 g H₂O/g) and reducing sugar content (8.05 mg GE/g), while tapioca flour showed superior swelling properties. The blends demonstrated complementary functional characteristics, with the LP30/TF70 formulation selected for meat substitute development based on optimal textural properties. The sensory evaluation revealed significant gender differences in acceptance, with women rating the product substantially higher than men across all attributes. The study successfully demonstrated the feasibility of transforming agricultural waste into a valuable functional ingredient, contributing to sustainable food production and representing the first comprehensive evaluation of L. cylindrica seed press cake for food applications. However, the study revealed limitations, including significant antioxidant loss during thermal processing (80–85% reduction); a preliminary sensory evaluation with limited participants showing gender-dependent acceptance; and a reliance on locally available tapioca flour, which may limit global applicability. Future research should focus on processing optimization to preserve bioactive compounds, comprehensive sensory studies with diverse populations, and an investigation of alternative starch sources to enhance the worldwide implementation of this valorization approach. Full article

With the rise in the marine industry and marine tourism, coral powder is increasingly used to make concrete for marine islands. This study proposes a three-parameter hydration model and a hydration kinetic model to predict the performance of coral powder concrete based on previous experimental data. The process of the proposed prediction model is as follows: 1. The input parameters of the three-parameter hydration model are calibrated for the first 7 days using the cumulative hydration heat per gram of cement. The maximum cumulative hydration heat (455.87 J/g cement) and the shape coefficient (−0.87) remain constant. In this study, the hydration rate coefficients for 0%, 10%, and 20% coral powder were 6.91, 6.19, and 5.55, respectively, showing decreases of 10.41% and 19.68% compared with the specimens without coral powder. 2. At 28 days, the cumulative heat release values per gram of cement for 0%, 10%, and 20% coral powder were 389.77, 395.69, and 401.62 J/g, showing increases of 1.52% and 3.04% for the specimens containing 10% and 20% coral powder, respectively. Meanwhile, the hydration degrees for 0%, 10%, and 20% coral powder were 0.855, 0.868, and 0.881, respectively, showing increases of 1.52% and 3.04%. Furthermore, the cumulative heat release values per gram of binder were 389.77, 356.12, and 321.29 J/g, showing decreases of 8.63% and 17.56% for specimens containing 10% and 20% coral powder, respectively. 3. Properties such as compressive strength, ultrasonic pulse velocity (UPV), and surface electrical resistivity were evaluated using the power function and the cumulative hydration heat per gram of binder. 4. At 28 days, the chemically bound water contents for samples with 0%, 10%, and 20% coral powder were 0.2402, 0.2197, and 0.1981 g/g binder, respectively. Moreover, the calcium hydroxide contents were 0.1848, 0.1690, and 0.1524 g/g binder, showing reductions of 8.53% and 17.52% in bound water and 8.54% and 17.53% in calcium hydroxide. 5. A hydration kinetic model is proposed, which can distinguish between the dilution effect and the nucleation effect of coral powder, unlike the three-parameter model, which cannot distinguish between the two effects. Furthermore, the input parameters of the hydration kinetic model remain unchanged for different mixtures, while the input parameters of the three-parameter model must be varied among mixtures. Parameter analysis of the hydration kinetic model indicated that a low water–binder ratio and a high coral powder substitution rate significantly improve the relative reaction level of cement. Full article

Using coral debris as coarse and fine aggregates and seawater as mixing water has been proposed to address transportation and material shortage issues in island and reef construction projects. However, the utilization of coral may result in impurities, such as shellfish and other marine organisms, which could impact the mechanical properties of the resulting concrete. The goal of this study is to find out how different amounts of shellfish and marine organism impurities affect the mechanical properties and microstructure of coral concrete. This study builds on the process of making full coral concrete. Substitution optimization is carried out using the response surface method (RSM), with the polynomial work expectation serving as a validation measure. The experimental findings indicate that impurities have an insignificant impact on the mechanical properties of coral concrete when their dosage is below 2%, causing a decrease of only around 6%. The mechanical properties of coral concrete containing shellfish and marine organism impurities exhibit a strong correlation at 28 days. SEM and XRD analysis revealed that the primary factor contributing to the decline of mechanical properties in coral concrete with shellfish and marine organism impurities is the weak strength of the impurity shell structure, in addition to the rehydration of internal biomass during the cement hydration process, leading to the formation of numerous small pores within the coral concrete. The results of an ANOVA test indicate that the model is statistically significant, with a p-value of less than 0.05. Full article

Alcohol-drinking culture may cause individuals to periodically experience unpleasant hangovers. In addition, ethanol catabolism stimulates the production of free radicals that may cause liver injury and further lead to the development of chronic alcoholic fatty liver disease. Although a number of studies have suggested that hydrogenated water may be consumed to act as free radical scavenger, its instability limits its application. In this study, we used coral hydrate (i.e., hydrogenated coral materials) as a more stable hydrogen source and evaluated its effects in a murine model of alcohol intoxication. In solution, coral hydrate exhibited much more stable redox potential than did hydrogenated water. Furthermore, administration of coral hydrate by oral gavage significantly prolonged the time to fall asleep and decreased the total sleep time in mice that received intraperitoneal injection of ethanol. The mice receiving coral hydrate also had lower plasma ethanol and acetaldehyde levels than controls. In line with this observation, hepatic expression of alcohol dehydrogenase, acetaldehyde dehydrogenase, catalase and glutathione peroxidase were all significantly increased by the treatment. Meanwhile, alcohol-induced upregulation of pro-inflammatory factors was attenuated by the administration of coral hydrate. Taken together, our data suggest that coral hydrate might be an effective novel treatment for alcohol intoxication. Full article

In this study, coralline-activated materials were prepared using ball-milled coral powder as cementitious material and coral sand as fine aggregate. XRF (X-ray fluorescence) and chemical dissolution tests were carried out to determine the content and reactivity of various elements in coral powder. The compressive strength of the developed composites was evaluated at different ages, and the formation and transformation of mineral crystals in coralline-activated samples were further analyzed by XRD (X-ray diffractometer). The results show that the calcium content in coral powder was as high as 89.5% (loss on ignition). However, only 56% of the active calcium could participate in the polymerization reaction. The silicon and aluminum content was too low, and the slag addition could improve the deficiency of silicon and aluminum in coral powder. With the increase in slag content (from 0% to 50%), the compressive strength of the composites increases significantly. Nevertheless, the enhancement is not pronounced when the slag content exceeds 50%. The increase in slag amount can stimulate the transformation of calcium minerals, e.g., aragonite and calcite, into hydrated calcium silicate and calcium aluminosilicate gels, which significantly enhances the resulting compressive strength. Full article

In this study, coral powder with different contents and levels of fineness were incorporated into cement; then, the pore structure of a coral powder–cement slurry was measured using the MIP test at days 3 days and 28, respectively. Neimark’s model, Ji’s model, and Pfeifer and Avnir’s model were also used to analyze the fractal characteristics of the coral powder–cement slurry. The results show that the coral powder–cement slurry has multifractal characteristics when using Neimark’s model, and the entire pore size range of the cement slurry can be divided into three parts: Region I (1–200 μm), Region II (70 nm–4 μm), and Region III (5–500 nm). The pore surface fractal dimension of both Regions I and III is less than 3, while that of Region II is greater than 3. This indicates that Regions I and III have obvious fractal characteristics, which Region II does not. Meanwhile, the pore surface fractal dimension of Region I is positively correlated with hydration age, while the pore surface fractal dimension of Region III is less affected by hydration age and coral powder contents. Ji’s model reveals that coral powder–cement slurry also has multifractal characteristics, but the entire pore size range of the cement slurry can be divided into two parts: Region I (5.482 nm–500 m) and Region II (120 nm–370 μm). The pore volume fractal dimension of Region I is greater than 2 and less than 2.5, while that of Region II is greater than 2.9 and less than 3. Therefore, both Regions I and II have fractal characteristics. In addition, the coral powder admixture, fineness, and age have large effects on the pore volume fractal dimension and pore size range of Region II. Pfeifer and Avnir’s model reveals that the entire pore size range of cement slurry can also be divided into Region I (5.482–600 nm), Region II (120 nm–10 μm), and Region III (5–365 μm), and that the pore surface fractal dimension of both Regions I and III is less than 3, while that of Region II is greater than 3. This indicates that Regions I and III have fractal characteristics, while Region II does not have fractal characteristics. Full article

Coral sand cement (CSC) mortar is increasingly used in reef projects, which is prepared by mixing coral sand with cement and water in certain proportions. Considering that early-age hydration behavior is closely related to the strength and durability of the mortar, the early-age hydration process and micro-morphology of CSC mortars with various water–cement ratios (W/C) and sand–cement ratios (S/C) were studied. A monitoring system based on FBG is proposed in this paper, which uses the high sensitivity and conformability of optical fiber to measure the hydration temperature and internal shrinkage strain simultaneously and continuously. The standard sand cement (SSC) mortar with the same sand gradation and mix proportion is also prepared for comparison. The micro-morphology is observed by a scanning electron microscope (SEM) for measurement results’ explanation. The results show that the variation of the hydration temperature and shrinkage strain with hydration time of both CSC mortars and SSC mortars follow a unimodal function. Differently, the peak hydration temperature for CSC is obviously lower than that of SSC. The peak temperature of CSC mortar decreases linearly with the increase in S/C, and the decrease rate of the peak temperature is higher for CSC with small W/C than that with higher W/C. For mortars with lower W/C, the peak shrinkage strain of CSC is larger than that of SSC. Meanwhile, for mortars with higher W/C, the peak shrinkage strain of CSC changes to be lower than that of SSC, which is attributed to the significant water absorption characteristic of CSC. Therefore, as an eco-friendly lightweight aggregate, CS is more suitable than SS for the design of high W/C and alleviating the hydration heat of mass concrete under the meeting of strength. Full article

Coral concrete has low cost and convenient materials, making it an excellent raw material for processing. However, its lower strength limits the application of coral concrete. Surface modification is expected to increase the properties of porous coral concrete. In this study, single and compound modification treatments were applied to the surface of a coral aggregate to improve its properties for promoting the mechanical performance of coral concrete. The results showed that the micro-aggregate effect and pozzolanic activity of granulated blast furnace slag (GBFS) and the permeability and polycondensation of sodium silicate (SS) could be mutually promoted. The GBFS and SS could effectively fill the pores of the coral aggregate, enhancing the properties of the aggregate, such as density and load-bearing capacity, and reducing the water absorption and crushing index by more than 50%. GBFS and SS could intensify and accelerate the hydration of cement, and generate a large number of hard hydration products at the interfacial transition zone (ITZ), which could strengthen the bonding between the aggregate and mortar, improving the strength of the ITZ. The compressive strength of the coral concrete was significantly increased. Full article

In this paper, an ultrahigh-strength marine concrete containing coral aggregates is developed. Concrete fabricated from marine sources is considered an effective and economical alternative for marine engineering and the construction of remote islands. To protect sea coral ecosystems, the coral aggregates used for construction are only efflorescent coral debris. To achieve the expected mechanical performance from the studied concrete, an optimal mixture design is conducted to determine the optimal proportions of components, in order to optimize the compressive strength. The mechanical properties and the autogenous shrinkage, as well as the heat flow of early hydration reactions, are measured. The hydration products fill up the pores of coral aggregates, endowing our concrete with flowability and self-compacting ability. The phases in the marine concrete are identified via X-ray diffraction analysis. The 28-day compressive and flexural strength of the developed marine concrete achieve 116.76 MPa and 18.24 MPa, respectively. On account of the lower cement content and the internal curing provided by coral aggregates, the volume change resulting from autogenous shrinkage is only 63.11% of that of ordinary reactive powder concrete. Full article

Due to sedentary lifestyle and harsh environmental conditions, gorgonian coral extracts are recognized as a rich source of novel compounds with various biological activities, of interest to the pharmaceutical and cosmetic industries. The presented study aimed to perform chemical screening of organic extracts and semi-purified fractions obtained from the common Adriatic gorgonian, sea fan, Eunicella cavolini (Koch, 1887) and explore its abilities to exert different biological effects in vitro. Qualitative chemical evaluation revealed the presence of several classes of secondary metabolites extended with mass spectrometry analysis and tentative dereplication by using Global Natural Product Social Molecular Networking online platform (GNPS). Furthermore, fractions F4 and F3 showed the highest phenolic (3.28 ± 0.04 mg GAE/g sample) and carotene (23.11 ± 2.48 mg β-CA/g sample) content, respectively. The fraction F3 inhibited 50% of DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate) and ABTS (2,2′-azino-bis (3-ethylbenzthiazolin-6-yl) sulfonic acid) radicals at the concentrations of 767.09 ± 11.57 and 157.16 ± 10.83 µg/mL, respectively. The highest anti-inflammatory potential was exhibited by F2 (IC₅₀ = 198.70 ± 28.77 µg/mL) regarding the inhibition of albumin denaturation and F1 (IC₅₀ = 254.49 ± 49.17 µg/mL) in terms of soybean lipoxygenase inhibition. In addition, the most pronounced antiproliferative effects were observed for all samples (IC₅₀ ranging from 0.82 ± 0.14–231.18 ± 46.13 µg/mL) against several carcinoma cell lines, but also towards non-transformed human fibroblasts pointing to a generally cytotoxic effect. In addition, the antibacterial activity was tested by broth microdilution assay against three human pathogenic bacteria: Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. The latter was the most affected by fractions F2 and F3. Finally, further purification, isolation and characterization of pure compounds from the most active fractions are under investigation. Full article

The utilization of coral waste is an economical way of using concrete in coastal and offshore constructions. Coral waste with more than 96% CaCO₃ can be ground to fines and combined with supplementary cementitious materials (SCMs) such as fly ash, silica fume, granulated blast furnace slag in replacing Portland cement to promote the properties of cement concrete. The effects of coral sand powder (CSP) compared to limestone powder (LSP) blended with SCMs on hydration and microstructure of mortar were investigated. The result shows CSP has higher activity than LSP when participating in the chemical reaction. The chemical effect among CSP, SCMs, and ordinary Portland cement (OPC) results in the appearance of the third hydration peak, facilitating the production of carboaluminate. CSP-SCMs mortar has smaller interconnected pores on account of the porous character of CSP as well as the filler and chemical effect. The dilution effect of CSP leads to the reduction of compressive strength of OPC-CSP and OPC-CSP-SCMs mortars. The synergic effects of CSP with slag and silica fume facilitate the development of compressive strength and lead to a compacted isolation and transfer zone (ITZ) in mortar. Full article

Cold-water corals (CWCs) are frequently found at cold seep areas. However, the relationship between fluid seepage and CWC development is not clear. Here, for the first time, we report the occurrences, species identification, mineralogy, carbon and oxygen isotopes, as well as elemental compositions of fossil CWC skeletons from gas-hydrate-bearing sediment in drilling cores from the South China Sea (SCS). Three sites (GMGS-08, GMGS-09B, and GMGS-16) were investigated but CWCs were only found at one site (GMGS-09B). Interestingly, the CWCs were found in three horizons and they were all embedded with authigenic carbonates. Three genera of fossil CWCs (Crispatotrochus sp., Solenosmilia sp. and Enallopsammia sp.) were identified. The CWC fragments are predominantly aragonite. The CWCs exhibit δ¹³C values between −8.4‰ and −0.6‰ that are significantly higher than δ¹³C values of the associated seep carbonates (δ¹³C values with an average of −55.6‰, n = 19), which indicates a carbon source other than methane for the CWCs. It appears that authigenic carbonates provide a substratum for coral colonization. Bathymetric high points, appropriate water temperature and stronger bottom-water currents at site GMGS-09B might be crucial to keep conditions favorable for the growth of CWCs in the studied area. In addition, high trace-element concentrations of Cr, Ni, Pb, U, Ba, Th, and Sr suggest that the CWCs are influenced by strong fluid seepage that can reach the water-sediment interface, and associated microbial activity. Hence, it also becomes evident that CWCs in hydrocarbon-rich seepage areas not only provide a critical constraint on the impact of fluid emission on the bottom water chemistry, but also are likely to be very precise recorders of the end time of cold seep activity. Full article

The ubiquitous metalloenzymes carbonic anhydrases (CAs, EC 4.2.1.1) are responsible for the reversible hydration of CO₂ to bicarbonate (HCO₃⁻) and protons (H⁺). Bicarbonate may subsequently generate carbonate used in many functional activities by marine organisms. CAs play a crucial role in several physiological processes, e.g., respiration, inorganic carbon transport, intra and extra-cellular pH regulation, and bio-mineralization. Multiple transcript variants and protein isoforms exist in the organisms. Recently, 16 α-CA isoforms have been identified in the coral Stylophora pistillata. Here, we focalized the interest on three coral isoforms: SpiCA1 and SpiCA2, localized in the coral-calcifying cells; and SpiCA3, expressed in the cytoplasm of the coral cell layers. The three recombinant enzymes were heterologously expressed and investigated for their inhibition profiles with sulfonamides and sulfamates. The three coral CA isoforms differ significantly in their susceptibility to inhibition with sulfonamides. This study provides new insights into the coral physiology and the comprehension of molecular mechanisms involved in the bio-mineralization processes, since CAs interact with bicarbonate transporters, accelerating the trans-membrane bicarbonate movement and modulating the pH at both sides of the plasma membranes. Full article

Carbonic anhydrases (CAs, EC 4.2.1.1) are widespread metalloenzymes used by living organisms to accelerate the CO₂ hydration/dehydration reaction at rates dramatically high compared to the uncatalyzed reaction. These enzymes have different isoforms and homologues and can be found in the form of cytoplasmic, secreted or membrane-bound proteins. CAs play a role in numerous physiological processes including biomineralization and symbiosis, as is the case in reef-building corals. Previously, molecular and biochemical data have been obtained at the molecular level in the branching coral Stylophora pistillata for two coral isoforms which differ significantly in their catalytic activity and susceptibility to inhibition with anions and sulfonamides. More recently it has been determined that the genome of S. pistillata encodes for 16 CAs. Here, we cloned, expressed, purified and characterized a novel α-CA, named SpiCA3, which is cytoplasmic and ubiquitously expressed in all the cell layers including the calcifying cells. SpiCA3 is the most effective CA among the coral isoforms investigated and the most efficient catalyst known up to date in Metazoa. We also investigated the inhibition profiles of SpiCA3 and compared it with those obtained for the two other isoforms in the presence of inorganic anions and other small molecules known to interfere with metalloenzymes. These results suggest that S. pistillata has adapted its CA isoforms to achieve the physiological functions in different physicochemical microenvironments. Full article