Search Results (862)

The objective of the present work was to investigate a possible processing route for a currently discarded material, niobium mineral tailings containing rare earth elements, from the largest niobium producer worldwide (CBMM), for use as a raw material for valuable products such as ferroniobium and rare earth concentrate. A study was conducted on the kinetics of the carbothermic reduction from hematite to magnetite (magnetizing roasting). Thermogravimetric tests performed in duplicate or triplicate were conducted at three different temperatures (700 °C, 800 °C and 900 °C) for 1 h with two times the stoichiometric quantity of the reductant (charcoal). Scanning electron microscopy (SEM) and X-ray diffraction (XRD) showed small amounts of magnetite in the samples reduced at 700 °C and 800 °C. At 900 °C, in accordance with the XRD analysis (Rietveld), almost all hematite was reduced to magnetite. The kinetic model that showed the best fitting was the Ginstling–Brounshtein model. The apparent activation energy was evaluated to be 206 kJ/mol, which is similar to the values reported in the literature for the activation energy of the Boudouard reaction. Full article

Fuels obtained from woody forest resources such as oaks have been traditionally used in various regions due to their availability and energy properties. In the search for sustainable bioenergy sources and the transition towards cleaner alternatives, biomass-derived fuels, such as charcoal and pellets, represent a relevant option for rural and urban communities. This study determines the chemical composition, physical and mechanical properties, and energy quality of pellets from two oak species (Quercus laurina and Q. rugosa) in San Sebastián Coatlán, Miahuatlán, Oaxaca. The chemical composition was determined in an Ankom fiber analyzer; the energetic, physical, and mechanical analysis was carried out with UNE-EN ISO and ASTM standards. On average, 56.18% and 54.63% cellulose, 17.81% and 17.87% lignin, and 13.96% and 13.78% hemicelluloses were obtained for Quercus laurina and Q. rugosa, respectively. Mechanical durability ranged from 87% to 95% for Q. laurina stump and Q. rugosa stem, respectively; for calorific value, values from 19.79 MJ Kg⁻¹ to 20.31 MJ Kg⁻¹ were recorded for Q. laurina stem and Q. rugosa stump, respectively. The forest biomass of both oak species is viable for pellet production. Full article

Biogas is once again emerging as a potential household cooking option that can help developing countries achieve energy targets. However, the adoption of biogas remains relatively slow, necessitating a diagnosis of the problem the review of literature identified. The review identified key factors influencing the adoption of household biogas technology, including policy and regulatory frameworks, financing mechanisms, public awareness, and socio-economic factors. Therefore, this study involved undertaking a survey where heads of 385 households were interviewed. The study found that low income of households, averaging USD 67/month, is a major constraint to biogas adoption, especially when dirty fuels cost little or nothing. In addition, a lack of awareness of the benefits of biogas over the available dirty fuels has the potential to limit its adoption. This explains why 99% of the households interviewed indicated firewood and charcoal were their first option, and 52% believed that these dirty fuels were dependable. Regardless of these bottlenecks, the study found that households are ready to try better cooking options. About 99% of households were interested in using biogas, and 94% wanted to learn more about biogas. Therefore, there is a need for increased awareness, and suppliers must adopt innovations that make biogas more accessible and competitive against traditional cooking fuels. Full article

Background: Tooth whitening is a widely sought-after cosmetic procedure, with various at-home and professional treatments available. This study compares the whitening efficacy of an activated charcoal toothpaste and a 6% hydrogen peroxide whitening pen under controlled in vitro conditions. Methods: Twenty freshly extracted human teeth were stained with a coffee solution and divided into two groups. Group A underwent daily applications of activated charcoal toothpaste for 30 days, while Group B received a single 5 min application of a 6% hydrogen peroxide whitening pen. Tooth color was assessed using the VITA Classical A1-D4 Shade Guide at baseline, mid-treatment, and post-treatment for Group A and at baseline and immediately after treatment for Group B. Results: The activated charcoal toothpaste exhibited a gradual whitening effect, with the most significant improvements occurring within the first two weeks (p < 0.01), after which the whitening effect plateaued. In contrast, the hydrogen peroxide whitening pen produced immediate and substantial whitening (p < 0.001). Statistical analysis using the Wilcoxon signed-rank test and Mann–Whitney U test confirmed the superior efficacy of the hydrogen peroxide treatment. Conclusions: The hydrogen peroxide whitening pen was significantly more effective in achieving rapid and substantial whitening compared to the activated charcoal toothpaste, which provided gradual but limited improvements. Further clinical studies are needed to evaluate the long-term color stability. Full article

This paper focuses on the study of the prehistoric art site at Penedo do Gato Rock Art Shelter (NW Spain) through an interdisciplinary collaboration. A key objective was to develop and implement a multi-analytical protocol for characterising prehistoric rock paintings with portable analytical techniques such as colour spectrophotometry and Raman spectroscopy. Additionally, three possible colouring materials collected during the archaeological survey of the site were investigated by means of X-ray diffraction, stereomicroscopy, and scanning electron microscopy (surface and cross-section modes) with the aim of determining their mineralogical composition and texture. The results indicate that hematite (α-Fe₂O₃) is the main component of the red motifs. Amorphous carbon has been found in several motifs. The presence of amorphous carbon on the rock suggests it may have been deposited onto the paintings by nearby bonfires; however, the potential use of charcoal as an additive in the red pigments to modify their colour should not be overlooked. Regarding the mineralogical composition of potential colouring materials, only one of the samples can be considered as a viable source. This was the only sample with a compact and homogeneous composition, rich in hematite, making it likely that, after grinding, it was used for painting. In contrast, the other collected samples either lacked hematite or contained only a thin layer of it. In these cases, it is unlikely that the hematite layer was extracted using tools to obtain the pigment. Full article

Incorporating solid waste into polymeric matrices has proven effective in developing composites with enhanced mechanical and thermal properties. This study investigates a composite based on recycled high-density polyethylene (HDPE), reinforced with fine charcoal particles, assessing its thermal, microstructural, and density properties. Two processing methods (compression molding and extrusion) and four charcoal concentrations (0%, 5%, 10%, and 15 wt%) were evaluated. Thermal characterization was performed using thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR). The microstructure was analyzed through scanning electron microscopy (SEM) and X-ray diffraction (XRD), while the density was determined via X-ray densitometry. SEM revealed increased porosity with charcoal addition. The thermal properties and crystallinity of the composites were not significantly affected by variations in the manufacturing method or charcoal concentration. FTIR analysis identified characteristic peaks, while TGA indicated mass loss between 400 and 500 °C, with a maximum decomposition temperature of 487 °C. XRD confirmed the semicrystalline structure typical of HDPE. Thus, incorporating charcoal residues can reduce the use of fossil-based materials while providing a sustainable application for industrial waste. Full article

Background: This study evaluated the effect of charcoal-containing toothpaste on the surface roughness of CAD/CAM lithium disilicate ceramic (e.max CAD) after simulated toothbrushing. Methods: Forty-eight e.max CAD ceramic specimens were divided into four groups (n = 12) and subjected to 18,000 brushing cycles using a toothbrushing simulator. The groups included Crest 3D White Charcoal, Colgate Optic White with Charcoal, Arm & Hammer Charcoal White, and a control group (conventional toothpaste). Surface roughness was measured with a profilometer before and after brushing, and scanning electron microscopy (SEM) was used for topographical analysis. Statistical analysis was performed using the Kruskal–Wallis test and post hoc comparisons. Results: Significant differences in surface roughness were found among the groups (p < 0.001). The mean roughness values were 540.70 ± 21.68 µm (Control), 294.88 ± 11.49 µm (Crest 3D White Charcoal), 1157.00 ± 52.85 µm (Colgate Optic White with Charcoal), and 593.37 ± 37.69 µm (Arm & Hammer Charcoal White). Post hoc analysis showed that Colgate Optic White with Charcoal had the highest roughness, which was significantly different from all other groups (p < 0.001). SEM analysis revealed severe surface degradation with Colgate Optic White with Charcoal, while Crest 3D White Charcoal caused minimal changes. Conclusions: Charcoal-containing toothpastes vary in abrasiveness, with Colgate Optic White with Charcoal causing the most significant surface roughness and damage to lithium disilicate ceramics. Full article

The Po Nagar Towers (Thap Ba) complex, an iconic heritage site of Cham culture and a nationally recognized special relic, has stood in Nhatrang, Vietnam, for over a thousand years. We report here a preliminary analysis of original ancient Cham bricks from the Po Nagar Towers using a combination of appropriate characterization techniques, including X-ray fluorescence (XRF), X-ray diffraction (XRD), Raman micro-spectroscopy, thermal dilatometry, compressive strength testing, and water sorption. Mechanical properties and firing temperatures of the ancient bricks have been determined to support the discussion on the likely technology used to make them. Specifically, they were made from clay, sand, plagioclases/feldspar, and grog mixed with intentionally added carbon precursor (charcoal powder), then fired at temperatures between 800 °C and 1000 °C to form lightweight bricks with a mass density of 1.3–1.6 kg/dm³ and an open porosity of 18–25%. The ancient Cham bricks have their texture and porosity to meet the requirements of the thin rubbing joint technique in tower construction and to contribute to the carvability and durability of Cham towers. A comparison is made with the bricks for tower restoration during the 2000s. Full article

Biodesulfurization (BDS) is a clean technology that uses microorganisms to efficiently remove sulfur from recalcitrant organosulfur compounds present in fuels (fossil fuels or new-generation fuels resulting from pyrolysis and hydrothermal liquefaction). One of the limitations of this technology is the low desulfurization rates. These result in the need for greater amounts of biocatalyst and lead to increased production costs. To mitigate this issue, several approaches have been pursued, such as the use of alternative carbon sources (C-sources) from agro-industrial waste streams or the co-production of high-added-value products by microorganisms. The main goal of this work is to assess the potential of strawberry tree fruit residue (STFr) as an alternative C-source for a BDS biorefinery using Gordonia alkanivorans strain 1B, a well-known desulfurizing bacterium with high biotechnological potential. Hence, the first step was to produce sugar-rich liquor from the STFr and employ it in shake-flask assays to evaluate the influence of different pretreatments (treatments with 1–4% activated charcoal for prior phenolics removal) on metabolic parameters and BDS rates. Afterwards, the liquor was used as the C-source in chemostat assays, compared to commercial sugars, to develop and optimize the use of STFr-liquor as a viable C-source towards cost-effective biocatalyst production. Moreover, the high-market-value bioproducts simultaneously produced during microbial growth were also evaluated. In this context, the best results, considering both the production of biocatalysts with BDS activity and simultaneous bioproduct production (carotenoids and gordofactin biosurfactant/bioemulsifier) were achieved when strain 1B was cultivated in a chemostat with untreated STFr-liquor (5.4 g/L fructose + glucose, 6:4 ratio) as the C-source and in a sulfur-free mineral-minimized culture medium at a dilution rate of 0.04 h⁻¹. Cells from this steady-state culture (STFr L1) achieved the highest desulfurization with 250 mM of dibenzothiophene as a reference organosulfur compound, producing a maximum of ≈213 mM of 2-hydroxibyphenil (2-HBP) with a corresponding specific rate (q_2-HBP) of 6.50 µmol/g(_DCW)/h (where DCW = dry cell weight). This demonstrates the potential of STFr as a sustainable alternative C-source for the production of cost-effective biocatalysts without compromising BDS ability. Additionally, cells grown in STFr L1 also presented the highest production of added-value products (338 ± 15 µg/g_(DCW) of carotenoids and 8 U/mL of gordofactin). These results open prospects for a future G. alkanivorans strain 1B biorefinery that integrates BDS, waste valorization, and the production of added-value products, contributing to the global economic viability of a BDS process and making BDS scale-up a reality in the near future. Full article

Processing methods affect the quality and, most importantly, safety of meat. The effects of various marinades, a kind of green processing technology commonly used in Poland, on PAH contamination in pork neck loins, the most frequently grilled pork meat, were investigated, including universal, pork, and honey mustard, as well as the most popular grilling tools. It is important to note that no such data have been published so far. Our previous study focused on poultry meat, another commonly grilled meat. PAH analysis was conducted using the QuEChERS–HPLC–FLD/DAD method and confirmed by the GC/MS method. Weight loss and changes in individual color parameters after grilling were also analyzed. Grilling on a charcoal grill without an aluminum tray caused statistically the greatest PAH contents. Some of these samples, according to Commission Regulation (EU) No. 915/2023 restrictions, should not be consumed by humans due to the high content of B[a]P (5.26–6.51 µg/kg). The lowest contamination levels overall were determined for the ceramic contact grill. Studies have also shown that the universal and pork marinades can reduce PAH contamination by about 24–29% for 4 heavy PAHs and by 31–32% for 15 PAHs, whereas the honey mustard marinade increases their accumulation in grilled products by 13% for 4 PAHs and 12% for 15 PAHs. Carefully choosing the grilling equipment, such as using electric grills instead of charcoal or using aluminum trays when grilling with charcoal and marinating the meat before grilling, is essential for food producers and consumers. These practices can significantly reduce the harmful health effects of PAHs, making them vital steps toward safer food preparation. Full article

This study investigates the production of biomass briquettes using waste coconut shell charcoal and cinnamon sawdust, bound by eco-friendly, non-edible binders: cassava peel starch, giant taro starch, and pine resin. The production process involved carbonization of coconut shells, followed by crushing, blending with sawdust, pressing, and a 12-day sun-drying period. The briquettes were tested for calorific value, density, compressive strength, and shatter resistance. The calorific values ranged from 26.07–31.60 MJ/kg, meeting the industrial standards, while densities varied between 0.83 g/cm³ and 1.14 g/cm³, ensuring compactness and efficient combustion. Among the binders, cassava peel starch provided the best bonding strength, resulting in high-density briquettes with superior durability and energy release, showing a calorific value and compressive strength of 2.11 MPa. Giant taro starch also improved durability, though with slightly lower calorific values but better bonding than pine resin. Pine resin, while contributing to high calorific values, reduced compressive strength with increased resin content, making it less suitable for high mechanical strength applications. Proximate analysis revealed that cassava peel starch-based briquettes had moisture content from 6.5% to 8.6%, volatile matter from 15.2% to 23.5%, ash content from 2.1% to 3.2%, and fixed carbon between 69% and 76.2%. Giant taro starch-based briquettes exhibited 63.2% to 75% fixed carbon, while pine resin-based briquettes had the highest fixed carbon content (66.4% to 78.3%), demonstrating the potential of non-edible adhesives for sustainable, high-performance fuel production. Full article

Background: Exposure to household air pollution (HAP) is one of the primary risk factors for acute lower respiratory infection (ARI) morbidity and mortality among children in low-income settings. This study aimed to examine the relative contribution of residing in deprived neighbourhoods and exposure to HAP on the occurrence of ARI among children using data from the 2014–2015 Chad Demographic and Health Survey (DHS). Methods: We applied multilevel modelling techniques to survey data of 2882 children from 372 communities to compute the odds ratio (OR) for the occurrence of ARI between children of respondents exposed to clean fuels (e.g., electricity, liquid petroleum gas, natural gas, and biogas) and respondents exposed to polluting fuel (e.g., kerosene, coal/lignite, charcoal, wood, straw/shrubs/grass, and animal dung). Results: The results showed that children exposed to household polluting fuels in Chad were 215% more likely to develop ARI than those not exposed to household air pollution (OR = 3.15; 95% CI 2.41 to 4.13). Further analysis revealed that the odds of ARI were 185% higher (OR = 2.85; 95% CI 1.73 to 4.75) among children living in rural residents and those born to teenage mothers (OR = 2.75; 95% CI 1.48 to 5.15) who were exposed to household polluting fuels compared to their counterparts who were not exposed. In summary, the results of the study show that the risk of ARI is more common among children who live in homes where household air-polluting cooking fuel is widely used, those living in rural areas, those living in socioeconomically deprived neighbourhoods and from the least wealthy households, and those born to teenage mothers in Chad. Conclusions: In this study, an independent relative contribution of variables, such as HAP from cooking fuel, neighbourhood deprivation, living in rural areas, being from a low-income household, having a mother who is a manual labourer worker, and being given birth to by a teenage mother, to the risk of ARI among children is established. Full article

Synthetic seed technology is an innovative in vitro technique that provides improved storage capabilities for vegetative propagules. Its success mostly depends on the encapsulation matrix’s composition and the encapsulation procedure. The present study focuses on optimizing an encapsulation protocol for short-term storage and germplasm exchange using micro-cuttings of Salix tetrasperma. Among the different synthetic seed types evaluated, double-layered synthetic seeds (DLSs) exhibited the highest re-growth (93.6%) on MS medium supplemented with meta-Topolin (mT) (5.0 µM) and α-naphthalene acetic acid (NAA) (0.5 µM) after 8 weeks of culture. Viability assessment of non-embryogenic synthetic seeds during low-temperature storage (4 °C) demonstrated the enhanced resilience of double-layered synthetic seeds (DLSs) compared to their single-layered (SLS) counterparts. Following acclimatization in Soilrite^®-filled cups, 82% of the plantlets were successfully established in a greenhouse after four weeks. The increased activity and concentration of antioxidants in DLS-derived plantlets suggest the potential role of the extra layer of alginate in mitigating the effects of low-temperature stress during storage. SCoT molecular analysis confirmed the genetic integrity of the synthetic seed-derived plants. Full article

The present study aimed to analyze the physicochemical properties and biological activity of an L-malic acid descaler. The treated water with L-malic acid descaler complies with EU Directive No. 2020/2184 for the quality of water intended for human consumption. The L-malic acid descaler contains L-malic acid as the active component, while polyethylene and activated charcoal function as structural and absorbent materials, respectively. The composition was analyzed in a licensed laboratory using Chemical Abstracts Service Number (CAS) and European List of Notified Chemical Substances (EINECS) standards. Fourier Transform Infrared (FT-IR) analysis confirmed the presence of hydroxyl (–OH), carbonyl (C=O), and carboxyl (–COOH) groups in L-malic acid descaler, which are connected with proton-donating ability, and redox activity. The biological activity was evaluated using Saccharomyces cerevisiae as a model system. The role of the YAP1 transcription factor, a key regulator of oxidative stress defense mechanisms, was also examined. The detrimental effects on a cellular level were induced by the well-known mutagen—methyl methanesulfonate (MMS). Our data revealed that yeast cells treated with such water decrease the MMS-induced superoxide anions (3.5-fold), total glutathione lipid peroxidation (1.5-fold), and total glutathione (3-fold) and increase cell survival (2-fold). In conclusion, water treated with L-malic acid descaler possesses antioxidant effects in yeast-cell-based tests, independent of YAP1 transcription factor activity. This study provides preliminary evidence that L-malic acid, when dissolved in water, significantly reduced MMS-induced superoxide anions, one of the biomarkers contributing to the genotoxic and carcinogenic effects of MMS. Full article

Preserved macro-botanical and charcoal remains collected from the Zhumucun site have revealed the paleodiet and agricultural production of a small settlement during the Liangzhu period. Further, they have also helped to reconstruct the landscape and social organization that occurred therein. The plant remains assemblage shows that rice was the main crop at this site; however, the appearance of the millets may also indicate the spread and communication between southern and northern China. An analysis of the discarded spikelets confirmed that rice was locally produced and processed. A study of charcoal helped restore the vegetation landscape in the settlement and provided valuable insights for reconstructing the functional zoning and agricultural production at the site. Following an analysis of the plant distribution and utilization patterns at the site, it became clear that the Zhumucun site functioned as a small agricultural settlement. Compared to other settlements from the Liangzhu period, the Zhumucun site likely supported a smaller population. The site could be divided into smaller groups, including facilities in residential areas, processing areas, tomb areas, and farming areas. Agricultural production at the Zhumucun site appears to have been highly coordinated, with activities carried out in a unified manner and primarily by local households. This efficient system of resource management likely reflects a well-organized labor structure, where food surpluses may have been redistributed to support other higher-level settlements. Full article