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Eggshells are an inorganic waste, and their accumulation rate is increasing globally, complicating waste management. However, the European Union defines eggshells as low-risk material that can be recycled and reused safely in other applications. Their chemical composition renders them an attractive precursor of calcium phosphate materials (CaPs). Because of their remarkable biocompatibility and capacity for natural degradation, CaPs are frequently employed in biomedical engineering applications. In this research, the wet precipitation method was employed for fabricating CaP powder. Initially, the eggshells were processed into CaCO3 powder and then reacted with HCl to obtain CaCl2 (aq). This reacted with Na2HPO4 to obtain a precipitate that was filtered and dried. The precipitate in powder form underwent X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) analysis to evaluate its microstructure, and elemental and phase composition. The results indicated that the recovered powder was brushite. [ABSTRACT FROM AUTHOR]

In the present study, the processing, characterization, and assessment of novel non-alcoholic and sugar-free drinks based on bioactive extracts from valuable natural sources, such as green tea enriched with Chios mastiha, are considered. Currently, the transition towards the consumption of healthy and sustainable food and beverages promoting human health and well-being is strongly encouraged and biologically active compounds from natural resources have a broad range of ap-plications in this sector. In this context, three beverages (all non-alcoholic, non-carbonated, and sugar-free) were created, including extracts of green tea with Chios mastiha, matcha green tea with Chios mastiha and louisa green tea with Chios mastiha, and an evaluation of their biological potential was performed. Specifically, an analysis of water, extracts, and additives for the beverage production was carried out. Microbiological and nutritional value determination was also conducted in samples of the three products. According to the experimental results, the novel health beverage produced from green tea enriched with Chios Mastiha extracts was found to have improved organoleptic characteristics and was microbiologically stable and safe for a period of 180 days from the production date at 25 °C. It is also considered stable and safe for 3 days after production, even if it remains open at 25 °C. In view of a possible scale-up of this application, safety, and preservation control should continue for at least 540 days from the date of production. In conclusion, the current research findings support the development of a novel non-alcoholic sugar-free health drink based on bioactive extracts from green tea enriched with Chios mastiha, to contribute to maintaining human health and also to strengthen the economy. [ABSTRACT FROM AUTHOR]

Featured Application: Potential application of the outcomes of the present study is feasible for the development of more targeted wellbeing measures in order to promote human health and prevent unfavorable pregnancy impacts related to increased oxidative stress due to pollution. Oxidative stress is an imbalance between reactive oxygen species production and antioxidant defense that can lead to reproductive disorders and poor pregnancy outcomes. Environmental pollution under climate change is involved in reactive oxygen species formation and may cause various dysfunctions of the reproductive system. Oxidative stress is a widespread factor that affects the physiology of the male and female reproductive systems, leading to high levels of DNA damage and infertility. Miscarriage, preeclampsia, and premature birth are all linked to oxidative stress. Environmental pollution induces excesses of oxidative stress by expanding ROS generation or overwhelming the physiological responses of the antioxidant defense system. This increases cellular damage, inflammation, and the development of numerous diseases. Here, we present a brief outline of the physiological and developmental roles that oxidative stress plays during pregnancy. We also offer some insights into the underlying mechanisms that have been put forth, which culminate in a summary of the harmful effects of oxidative stress that have an environmental origin in pregnancy-related complications. The current work may motivate the design of more focused wellbeing measures in order to prevent and promote human health and anticipate unfavorable pregnancy outcomes. [ABSTRACT FROM AUTHOR]

Featured Application: Potential application of the outcomes of the present study is feasible, for wastewater bioremediation with concurrent cost-efficient biofuel production, along with value-added health product and biofuel development, while also reducing the carbon footprint, certainly after implementation of the necessary regulation sandboxes, to promote environmental and human health protection and also job creation and economy strengthening. In the current study, the cultivation of microalgae on wastewater-based substrates is investigated for an effective natural wastewater treatment that also generates biofuels and value-added products beneficial to human health. Additionally, the health of ecosystems can be evaluated via microalgae. The utilization of microalgae as bioindicators, biofuel producers, and wastewater treatment providers, under the biorefinery concept, is covered in this article. In fact, bioremediation is feasible, and microalgae culture can be used to efficiently process a variety of effluents. Along with wastewater processing and the creation of value-added substances, bioconversion concurrently offers a viable and promising alternative for reducing CO2 greenhouse gas emissions to contribute to climate change mitigation. The microalgal biorefinery being considered as the third generation is unique in that it addresses all the aforementioned problems, in contrast to lignocellulosic biomass from agricultural waste in second-generation biorefineries and edible crops in first-generation biorefineries. In particular, one of the most promising natural resources for the manufacture of biofuel, including biodiesel, bioethanol, biomethane, and biohydrogen, is found to be microalgae. Furthermore, products of high value, like fatty acid methyl esters, astaxanthin, β-carotene, DHA, and EPA can be made. Hence, microalgal biomass offers a substitute for the development of biofertilizers, bioplastics, pharmaceuticals, cosmetics, animal and aquatic feeds, and human nutrition products, thus promoting human and environmental health. [ABSTRACT FROM AUTHOR]

Greek lignite reserves are mainly located in the northwestern part of the country (Region of Western Macedonia, Greece), reaching a total of 5 billion tons. Considering that Greece is planning to stop burning lignite for electricity production, the recovery of the CH4 trapped in lignite coalbed reservoirs can be a valuable alternative for power generation and may help to reduce the direct emissions of methane during mining activities. The aim of the present study was to evaluate the LCBM in the Region of Western Macedonia, Greece (Ptolemaida basin). In order to assess the LCBM that could be extracted, three samples were collected from an active mine and were subjected to desorption experiments at different temperatures (25 °C, 50 °C, 100 °C, and 150 °C) by channeling high purity Ar gas at 1 atm of pressure. According to the results, the highest amount of CH4 was extracted during the desorption process at 50 °C, while the total amount of CH4 from all three samples was 0.82 m3/kg, confirming the presence of CH4 in the lignite deposits. Finally, a SWOT analysis was carried out that shows the strengths and opportunities against the weaknesses and threats of a potential LCBM exploitation in Greece, while also taking into account the social, economic, and environmental nexus. [ABSTRACT FROM AUTHOR]

The growing urban population and increased use of healthcare services have brought significant attention to the safe and sustainable management of medical waste. Selecting the proper technology in medical waste management (MWM) represents one of the most critical challenges for decision-makers to ensure public health. In order to evaluate and choose the best MWM methodology, the current research provides a novel multi-criteria decision-making (MCDM) strategy for a variety of social stakeholders, to compute criteria weights, decision-making weights, and alternative ranking algorithms. The suggested structure addresses uncertain assessments of alternatives by extending weighting and ranking methods to acquire the decision-making weight and rank the MWM alternatives based on uncertain conditions. It also uses 'intuitionistic fuzzy' linguistic variables to indicate criteria weights. To assess all the factors pertaining to the sustainability of MWM actions, this study suggests the creation of a decision support system (DSS). Our DSS is built upon a novel strategy that utilizes a collection of MCDM models that are grounded on contemporary intuitionistic fuzzy logic methodologies. Alternative scenarios have been assessed for the instance of Greece, after specialists in the healthcare management field imposed 17 criteria and sub-criteria. The IF-MCDM methodologies used were the Intuitionistic Fuzzy DEMATEL, TOPSIS, and CORPAS. The alternative scenarios ranged from the prioritizing of safety laws and regulations to public acceptance and awareness, with the handling of hazardous risks and transportation playing a crucial part in the process. All ensemble methods produced the same ranking of the alternatives, demonstrating that safety and risk avoidance is the most significant scenario for sustainable urban development and public health. [ABSTRACT FROM AUTHOR]

Lignite combustion class-C (highly-calcareous) fly ash and bottom ash were sintered employing two-step sintering (TSS) and compared to conventionally sintered ones. TSS sintering is a new promising approach mainly used to obtain effectively densified ceramics. This alternative process is generally characterized by the absence of the final stage of grain growth occurring upon conventional sintering and by the development of nanograin microstructure. The ceramic microstructures successfully obtained in the present research were characterized by means of X-ray diffraction and scanning electron microscopy coupled with energy dispersive X-ray analysis as well as by density measurements. The effectiveness of the solidification process was thoroughly studied, and the specific microstructural features attained are compared between each other and evaluated in relation to the sintering method applied. The results show that the valorization of lignite calcareous ashes into ceramic materials is feasible through different sintering techniques.

The aim of the current research was to investigate and compare the total phenolic content and antioxidant capacity of sweet pepper cultivars at different development and maturation stages, in order to optimize the beneficial effects. For that purpose, three important sweet pepper cultivars, namely Dolmy-F1, Yahoo-F1 and Florinis-NS-700, were cultivated in a greenhouse. Their total phenolic content, ascorbic acid content and antioxidant properties were assessed at different development and maturation stages. In the aforementioned cultivars, the total phenolic content ranged from 345.2 to 602.1, 404.9 to 794.5, and 795.7 to 2220.3 μg GAE g-1 FW respectively. The ascorbic acid content ranged from 236 to 957, 258 to 1157, and 410 to 1550 μg AA g-1 FW respectively. The highest antioxidant activity was noted at the red maturity stage. Particularly the cultivar Florinis NS 700 was found to possess higher total phenolic, flavonoid phenol, non-flavonoid phenol, ascorbic acid contents, and greater antioxidant capacity, compared to the other cultivars. The results of our study recommend the consumption of the sweet peppers at red maturity stage, for achieving the maximum health-beneficial effects. [ABSTRACT FROM AUTHOR]

The transformation of both calcareous and siliceous Greek power station by-products (lignite ashes) into novel composite materials with photocatalytic properties for environmental application was investigated. Particularly, a comparison between the development of coated ceramic substrates and the modification of ash surfaces is attempted. Specifically, a) the sintering process (1000 °C, 2 h) of both fly and bottom ash (either calcareous or siliceous) for their conversion into compacted ceramic substrates coated with TiO2 slurry and then further thermally treated (500 °C, 1 h) to acquire TiO2 film consistency onto the ceramic substrate and b) the process of TiO2 precipitation on lignite ash surfaces in acidic solution after neutralization, and estimation of the TiO2 percentage, are compared. The microstructures obtained were examined by XRD and SEM-EDX analysis. Vickers microhardness was also determined for the ceramic microstructures, with satisfactory results (up to 356HV). The energy gap measurements of the coatings were found to be between 3.02eV and 3.17eV, which is located between the energy gap of anatase (3.23eV) and rutile (3.02eV). The coating mass was about 0.059 g/cm2. The photocatalytic activity under visible and UV irradiation was investigated in aqueous solutions of methylene blue and methyl orange organic dyes, with encouraging results. A main advantage of the processes proposed is the immobilization of TiO2 onto largely available secondary resources, which can lead to production of value-added 'green' photocatalysts for the treatment of industrial effluents in the framework of circular economy. [ABSTRACT FROM AUTHOR]

The present communication reports the development of reliable building bricks with improved thermal insulation behavior through substitution of the water mixed with the standard ceramic clayey raw materials with olive-mill wastewater (OMWW). This endeavor will contribute to circular economy and environmental protection as well as possible energy savings and CO2 emission reductions. OMWW is an aqueous by-product generated in large amounts during olive oil production processes. It is characterized by high COD values, low biodegradability, high toxicity, acidic pH, a high concentration of potassium and high solid matter content. Therefore, finding eco-friendly and economically viable solutions for OMWW treatment and valorization represents a significant challenge in the oilproducing countries, in order to avoid severe environmental problems from the uncontrolled disposal of this effluent. For that purpose, a series of ceramic brick specimens are fabricated with the introduction of either olive-mill wastewater or water employing a pilot-plant simulation of the industrial brick manufacturing procedures. The brick thermal conductivity and the mechanical performance are evaluated. According to the results obtained the replacement of fresh water by olive-mill wastewater in the ceramic manufacturing provides a production of lighter building bricks of a decreased thermal conductivity (hence increased thermal insulation capability) as well as an acceptable and a reliable mechanical strength. Furthermore, the energy consumption measurements reveal energy savings of as much as 30% attained during the brick firing. [ABSTRACT FROM AUTHOR]

This research aims at the utilization of both calcareous and siliceous lignite ashes, by-products of lignite combustion in power plants, toward a development of new materials of an environmental benefit. The possibility of fly and bottom ash surface modification by anatase and rutile (titanium dioxide structures) is investigated. The precipitation of TiO2 from an acidic solution on lignite ash surface is studied and the percentage of TiO2 coating obtained is found ranging from 11 to 55%. The latter microstructure is examined by XRD and SEM-EDX taking into consideration the ashes particle size (as received and < 45 µm), the solution pH (5.5 - 7.5), the ageing time (1 and 3 h) and the sintering temperature (300°C, 500°C, 700°C) applied. Anatase and rutile crystalline structures are observed within the whole heat treatment range. The main advantage of the process reported refers to titania immobilization onto a cheap porous substrate providing an additional solution to liquid wastes treatment by photocatalysis. [ABSTRACT FROM AUTHOR]

The aim of the current research is the beneficial utilization of steel mill scale (MS) as admixture in clayey raw materials at high percentages up to 100% for manufacturing innovative engineering ceramics by powder metallurgy processes. Various MS/clay mixtures were cold compacted at 20 tn load using an automated hydraulic press to form series of 5 cm diam. disc-shaped specimens. The specimens so-produced were sintered in a programmable electric furnace for final consolidation by controlled heating up to 950 °C for 2h. Weight and dimensions changes upon sintering, as well as physico-mechanical properties of sintered specimens were determined in relation to the % MS content. Microstructural examination was conducted by SEM-EDAX. From the experimental results, the substitution of MS for clays is feasible and a tendency for mechanical properties enhancement is recorded with increasing the industrial residue percentage, thus rendering MS a suitable and interesting starting material for the elaboration of engineering ceramics. This endeavor can also contribute to the sustainable management of this industrial residue towards circular economy and environmental protection. [ABSTRACT FROM AUTHOR]

Nowadays, several thermal treatment procedures and technologies are being used for in ceramic processing. The application of microwave irradiation in ceramic manufacturing, for the consolidation of the final ceramic structure, has many energy and economical avails, while at the same time it is environmentally benign. In this work, the microwave irradiation potential usage in energyefficient ceramic manufacturing is explored via a comprehensive literature review. Specifically, the advantages/disadvantages of the microwave irradiation compared to conventional heating technologies is discussed. Three different classes of ceramic materials, with industrial significance, are considered: a) bulk ceramics, b) electroceramics and c) bioceramics. Furthermore, future applications which may attract commercial concernment are also pointed out. [ABSTRACT FROM AUTHOR]

The amounts of ashes from circulating fluidized bed (CFB)-combustion steadily increase with the increasing rate of implementation of this environmentally-friendlier technology for firing solid fuels in power generation units. Therefore, beneficial uses of these powdery by-products, which possess particular characteristics, should be identified instead of landfill them at significant environmental and economic impact. Their valorization in the manufacturing of value-added ceramics is a challenging research area. In the present study, CFB-coal combustion fly ashes, mainly bearing Si-Al phases, were utilized as 100% raw materials for the synthesis of ceramics by powder metallurgy (PM) techniques. Test specimens were fabricated by powder cold pressing followed by sintering at 900, 1000 or 1100 °C. The produced materials were characterized by means of XRD and SEM-EDAX. Shrinkage upon sintering, apparent density, water absorption capability and Vickers microhardness were determined. The experimental results show that the recycling of CFB-fly ashes towards PM ceramics development is feasible. In fact, integral light-weight materials are obtained, exhibiting successfully-densified ceramic microstructures where quartz phases prevail. The physico-mechanical properties are proved to be influenced by the starting ash composition and the sintering temperature. The so-produced ceramics possess the potential to be tailored appropriately to meet requirements for specific applications of possible commercial interest. [ABSTRACT FROM AUTHOR]