Metal Content Research Articles

Studies on the content of toxic metals in teeth: A narrative review of literature.

The presence of toxic metals in the human environment can have detrimental effects on people's wellbeing. This literature review examines the ways in which various environmental and non-environmental factors can contribute to the accumulation of heavy metals in hard dental tissues. It is of the utmost importance to ensure the safety of the environment by restricting the presence of toxic metals originating from both industrial and non-industrial sources. The aim of this study is to analyze current research and identify the primary sources of heavy metal exposure and the mechanisms by which these metals are deposited in dental tissues. Moreover, the objective of this review is to synthesize data from various studies to determine the main environmental and non-environmental sources of toxic metal exposure that contribute to their presence in dental tissues, as well as the biological and chemical processes that are responsible for the deposition of heavy metals in hard dental tissues. Additionally, the review aims to assess the impact of heavy metal accumulation on dental health and its potential systemic effects on overall well-being. The accumulation of heavy metals in the teeth is influenced by a number of factors, such as age, systemic conditions, the nutritional status, and dental caries. The presence of supernumerary teeth results in altered levels of microelements, including an increase in cadmium (Cd) and copper (Cu). Additionally, smoking exacerbates toxic metal accumulation, especially Cd and lead (Pb), and disrupts the balance of essential minerals within the teeth. These findings underscore the impact of environmental pollution on dental health and highlight the potential of teeth as biomarkers of environmental exposure, emphasizing the need for continued research to address the health risks associated with environmental toxins.

Regularity of zinc, copper, and lead distribution in different size fractions of Rostov-on-Don urban soil aggregates

: The article is devoted to the study of zinc, copper, and lead content in the soils of Rostov-on-Don. Soil samples were collected from full-profile sections located in different districts of the city and suburbs of Rostov-on-Don. The group of anthropogenically disturbed soils included Urbic Technosol urbanstratozems and replantozems, as well as urbanized chernozems Calcic Chernozems (Technic). Natural soils of recreational areas are represented by migration-segregation chernozems Calcic Chernozems (Pachic). The study was carried out using atomic absorption spectrometry and X-ray fluorescence analysis to determine metal content. Soil structure was determined by the Savvinov method (dry sieving) (<0.25; 1–2; 3–5; 5–7; >10 mm). Statistical analysis of the Wilcoxon criterion for related samples was performed to identify relationships. The main objective of the study was to assess the heavy metal content in different size fractions of aggregates and the ability of structural fractions to accumulate zinc, copper, and lead. Structural aggregates of different sizes differ in their ability to accumulate zinc, copper and lead. Zinc, including its mobile compounds, is predominantly accumulated in microaggregates. The content of gross copper and especially lead is confined to larger aggregates. At the same time, mobile copper compounds are concentrated in microaggregates and in fractions larger than 10 mm. Mobile lead compounds are distributed in fractions of different sizes quite uniformly in all studied soils.

Enhanced phosphorus adsorption using modified drinking water treatment residues: A comparative analysis of powder and alginate bead forms

This study provides an analysis of the phosphorus adsorption efficacy of three modified drinking water treatment residues (MDWTRs): MDWTR-P (powdered form), MDWTR-D2, and MDWTR-D5 (alginate bead-entrapped forms with bead diameters of 2 mm and 5 mm, respectively). The preparation process involved washing and drying the drinking water treatment residue, followed by grinding and sieving to achieve particle sizes below 90 μm. The residue was then incinerated at 600 °C in oxygen-limited conditions. Subsequently, the MDWTR was formulated into alginate beads by mixing with sodium alginate and FeCl3 solutions, resulting in spherical particles of specified diameters. The evaluation of surface area, pore volume, pore size, and CHN concentration revealed that MDWTR-D5 possesses the largest surface area (284.7 m2 g−1) and highest micropore volume (0.04 cm3 g−1), indicating a greater capacity for adsorption. SEM-EDS analysis demonstrated significant compositional changes post-treatment, particularly elevated phosphorus levels, confirming effective adsorption. Metal content analysis indicated high aluminum levels in MDWTR-P and increased iron content in MDWTR-D5. Toxicity Characteristic Leaching Procedure (TCLP) and in vitro bioaccessibility (IVBA) tests confirmed the non-hazardous nature of all MDWTRs, ensuring their safety for environmental applications. Kinetic analyses using pseudo-first-order, pseudo-second-order, and intraparticle diffusion models highlighted the superior performance of MDWTR-D5, with the highest equilibrium adsorption capacity and initial adsorption rate across all tested concentrations, suggesting both high efficiency and rapid adsorption potential. Further validation using Langmuir and Freundlich isotherms revealed MDWTR-D5's highest monolayer adsorption capacity (22.88 mg g−1) and Freundlich adsorption capacity parameter (6.97 mg g−1). Statistical analysis via one-way ANOVA confirmed significant differences in phosphorus concentrations among the MDWTRs samples (p-value <0.001), consistently underscoring MDWTR-D5's superior adsorption performance. These findings highlight MDWTR-D5's potential as an effective adsorbent for phosphorus removal in wastewater treatment, emphasizing its applicability in environmental remediation strategies.

Co-hydrothermal carbonization of lignocellulosic biomass and swine manure: Optimal parameters for enhanced nutrient reclamation, carbon sequestration, and heavy metals passivation

Hydrochar, the primary product of hydrothermal carbonization (HTC) of wet organic waste, is recognized as a versatile, carbon-abundant material with diverse applications. However, optimizing its performance for specific uses remains challenging. Therefore, this study introduced a co-HTC process involving carbon-rich lignocellulosic materials and ash-rich livestock manure [i.e., Zanthoxylum bungeanum branch residue (ZB) and swine manure (SM), respectively]. The impacts of HTC temperature (i.e., 180 °C, 220 °C, and 240 °C) and mass ratios (i.e., 1:0, 7:3, 5:5, 3:7, and 0:1) on hydrochar properties (e.g., pH, EC, nutrient contents, heavy metal content and availability, chemical stability, etc) and the characteristics of process water were evaluated. Results reveal that co-HTC dramatically improved the quality of hydrochars compared with that derived from a single feedstock. Notably, the ZB:SM ratio had a more substantial impact on total nutrient content, carbon stability, and heavy metal accumulation and mobility. Additionally, the synergistic effects of ZB and SM were greatly dependent on the HTC temperature. By adjusting the feedstock mass ratio and HTC temperature, a highly-functionalized hydrochar can be produced. For example, hydrochars produced at 240 °C with a 7:3 ZB to SM ratio (HC240-7) is optimal for degraded soil amendment, enhancing carbon sequestration and nutrient supplementation. Results from this study could provide valuable insights for improving waste management through HTC and expanding the environmental and agricultural application of hydrochar.

Renewable Diesel Production over Mo-Ni Catalysts Supported on Silica

Nickel catalysts promoted with Mo and supported on silica were studied for renewable diesel production from triglyceride biomass, through the selective deoxygenation process. The catalysts were prepared by wet co-impregnation of the SiO2 with different Ni/(Ni + Mo) atomic ratios (0/0.84/0.91/0.95/0.98/1) and a total metal content equal to 50%. They were characterized by XRD, XPS, N2 physisorption, H2-TPR, and NH3-TPD. Evaluation of the catalysts for the transformation of sunflower oil to renewable (green) diesel took place in a high-pressure semi-batch reactor, under solvent-free conditions. A very small addition of Mo, namely the synergistic Ni/(Ni + Mo) atomic ratio equal to 0.95, proved to be the optimum one for a significant enhancement of the catalytic performance of the metallic Ni/SiO2 catalyst, achieving 98 wt.% renewable diesel production. This promoting action of Mo has been attributed to the significant increase of the metallic Ni active phase surface area, the suitable regulation of surface acidity, the acceleration of the hydro-deoxygenation pathway (HDO), the creation of surface oxygen vacancies, and the diminution of coke formation provoked by Mo addition.

Stable isotopic evidence of cadmium enrichment in soils of black shale distribution areas

Black shale-derived soils exhibit significant heavy metal enrichment, notably cadmium (Cd) enrichment. This study pioneered the reporting of δ114/110Cd isotopic values within a black shale-soil system, offering novel insights into the geochemical behaviors and enrichment mechanisms of Cd during soil formation processes influenced by weathering. Systematic rock‒soil sampling was conducted on the lower Cambrian Hetang Formation in western Zhejiang, China, which is characterized by Cd-rich black shale. Employing analytical methods, including principal component analysis and multiple linear regression, we investigated the factors influencing heavy metal content in soil, such as element dissolution during weathering, soil pH, and the presence of iron-manganese oxides, sulfides, organic matter, and clay minerals. Our findings revealed a compositional range of δ114/110Cd in black shale (1.93‰–3.31‰) contrasting with that in adjacent soils (0.31‰–1.82‰), illustrating significant Cd isotopic fractionation during weathering, where heavier Cd isotopes are preferentially leached, and lighter isotopes are enriched in the soil in association with iron-manganese oxides. This research not only deepens the understanding of Cd enrichment mechanisms within the rock‒soil system against a black shale geological background but also elucidates the formation processes of soil Cd pollution in areas with a high geochemical background.

Sentinel-2 Multispectral Satellite Remote Sensing Retrieval of Soil Cu Content Changes at Different pH Levels

With the development of multispectral imaging technology, retrieving soil heavy metal content using multispectral remote sensing images has become possible. However, factors such as soil pH and spectral resolution affect the accuracy of model inversion, leading to low precision. In this study, 242 soil samples were collected from a typical area of the Pearl River Delta, and the Cu content in the soil was detected in the laboratory. Simultaneously, Sentinel-2 remote sensing image data were collected, and two-dimensional and three-dimensional spectral indices were established. Constructing independent decision trees based on pH values, using the Successive Projections Algorithm (SPA) combined with the Boruta algorithm to select the characteristic bands for soil Cu content, and this was combined with Optuna automatic hyperparameter optimization for ensemble learning models to establish a model for estimating Cu content in soil. The research results indicated that in the SPA combined with the Boruta feature selection algorithm, the characteristic spectral indices were mainly concentrated in the spectral transformation forms of TBI2 and TBI4. Full-sample modeling lacked predictive ability, but after classifying the samples based on soil pH value, the R2 of the RF and XGBoost models constructed with the samples with pH values between 5.85 and 7.75 was 0.54 and 0.76, respectively, with corresponding RMSE values of 22.48 and 16.12 and RPD values of 1.51 and 2.11. This study shows that the inversion of soil Cu content under different pH conditions exhibits significant differences, and determining the optimal pH range can effectively improve inversion accuracy. This research provides a reference for further achieving the efficient and accurate remote sensing of heavy metal pollution in agricultural soil.

Rhenium and related valuable metals in the oil shales of the Volga basin

The results of study of the content of rhenium and other valuable metals in the oil shales of the Volga basin are presented. The new data on precise determination of Re, Co, Ni, Cu, Zn, U and other metals by inductively coupled plasma mass spectrometry have been published. The content of the studied metals were compared with clarks in carbonaceous shales. The association of metals with rhenium (Mo, U, Co, Ni, Cu, Zn, Se, Ag, Sb) has been isolated in oil shales. The organic matter of oil shales acts as a rhenium concentrator, and apparently Mo, U. The preferred petrographic type of oil shales for the concentration of rhenium in them is the colloalginite-vitrinite-clay type. The rhenium-bearing and metalliferous content of the Volga shales is compared with the contents of rhenium and a number of other valuable metals in dictyonema shales of the Baltic sedimentary basin.

Comparative Study of Steel Mill Dust Leaching with Phosphoric Acid and Sodium Hydroxide

Steel mill dust (SMD), produced by electric arc furnaces, is a highly polluting industrial waste due to its high content of metals (Zn, Fe, and Pb) and fine particle size (ca. 5.4 µm). This residue can be valorized to recover Zn using pyro and hydrometallurgical methods, with hydrometallurgy offering greater selectivity and lower energy costs. However, composition of SMD presents a challenge in identifying an optimal leaching agent. This study investigates the preferential extraction of Zn using two leaching agents, namely 150 g L−1 (1.5 M) phosphoric acid (H3PO4) and 240 g L−1 (6 M) sodium hydroxide (NaOH), in a two-stage leaching process (80 °C). Metallic Zn from the alkaline pregnant solution was recovered by electrodeposition (750 A/m2, graphite anode, stainless-steel cathode) and smelting (450 °C). The samples of SMD contained 26.3% Zn, 20.1% Fe, and 0.9% Pb, in compounds such as magnetite (Fe3O4), zincite (ZnO), and franklinite (ZnFe2O4). Each leaching agent successfully attained a 99% Zn recovery, demonstrating the proposed procedure’s high efficacy. However, H3PO4 leached also Fe and corroded the cathode during electrodeposition, thereby restricting the final recovery of metallic Zn. NaOH demonstrated greater selectivity for Zn over Fe and Pb, producing high-purity Zn deposits on the cathode by electrodeposition and 99% metallic zinc by smelting.

An improvement for enrichment and purification of germanium using carbonyl acid extractants

Germanium is a strategic metal that is challenging to enrich and purify without any side effects, especially stability and selectivity. Here the role of carbonyl acid in selective separation of germanium from complex industrial liquids was highlighted. Integrating theoretical and experimental analyses, carbonyl acids exhibit strong binding ability and high selectivity to germanium was demonstrated. The first set of carbonyl acid extractant (CAE) for germanium extraction was successfully synthesized with a solubility of less than 50 mg/L at pH = 0. The process analysis exhibits the extraction rate of germanium in a single stage by CAEs exceeds 99.9 %, while the separation factor surpasses 103, far beyond 101 of hydroxamic acids. Furthermore, the stripping rate for germanium in a single stage exceeds 83.0 %, with germanium accounting for over 99.9 % of the total metal content in the stripping solution. The CAE extraction process is straightforward and characterized by high germanium separation efficiency. The development of CAE not only realises the stable, green, low-carbon, and high-efficiency purification of germanium, but also the universality and inspiration of CAE make it highly significant and valuable in both theoretical research and practical applications.

Comprehensive study on physicochemical properties of materials based on titanium suboxides

This study focuses on the surface structures and microstructural changes of titanium dioxide nanotubes, when electrochemically coated with platinum and/or palladium. Ti samples anodized in a fluorine-containing electrolyte exhibit self-organized nanotubes of varying diameters with open pores. Annealing at 773 K led to compaction of the porous layer, the formation of cracks, and the appearance of corrugation in the nanotubes. The deposition of platinum produced a transition from a nanotubular surface structure to a microcrystalline structure consisting of rutile crystallites. The palladium-coated samples showed fused blocks characteristic of titanium suboxides. The tubular structure was preserved, even after crystallization. SEM images revealed a comb-like pattern in coatings with varying metal content. XRPD analysis confirmed the presence of anatase and elemental titanium. PdO was detected on the surface of the thermally treated samples. For samples co-treated with Pd and Pt, mutual diffusion of the two metals took place during the heat treatment. The findings reveal surface characteristics, metal deposition effects, and phase composition of titania nanotubes, providing valuable insights for further research.

Biochar Derived from Sewage Sludge: The Impact of Pyrolysis Temperature on Chemical Properties and Agronomic Potential

The rising volume of sewage sludge from urbanization poses substantial environmental and public health concerns, underscoring the urgency for the implementation of effective waste management strategies. The objective of this study was to evaluate the influence of pyrolysis temperature on the chemical composition and agronomic potential of biochar derived from sewage sludge. The pyrolysis process was conducted at temperatures ranging from 400 °C to 800 °C, and the resulting biochar was analyzed for pH, electrical conductivity, metal content, and carbon fractions. Additionally, phytotoxicity tests were conducted to assess the impact of the biochar on plant germination. The findings indicated that elevated pyrolysis temperatures resulted in an elevated alkalinity, electrical conductivity, and concentration of alkali metals in the biochar. Conversely, these processes resulted in a reduction in total organic carbon content and an increase in heavy metal content, which may limit the potential for biochar to be used in agricultural applications. The phytotoxicity tests indicated that the biochar produced at lower temperatures (400 °C) exhibited positive effects on plant growth when administered at doses of 5 and 10 t·ha−1. Conversely, the biochar produced at higher temperatures (800 °C) demonstrated significant toxicity. The findings indicate that the pyrolysis temperature is a critical factor in determining the suitability of biochar for agricultural applications. The production of biochar at lower temperatures may offer agronomic benefits, whereas the use of higher temperatures increases stability but is associated with the risk of higher heavy metal concentrations.

Health risk assessment of heavy metals in groundwater sources: carcinogenic and non-carcinogenic evaluation

ABSTRACT Persistent exposure to arsenic, chromium, cadmium, lead, and selenium in drinking water above permissible levels poses significant health risks, including increased incidences of skin, lung, bladder, and kidney cancers. This study evaluated 34 water samples from Rupnagar district, Punjab, for heavy metal content. Health risks were assessed using hazard quotient (HQ) and chronic daily intake metrics. Aluminium concentrations were highest in Block Nurpur Bedi (36.43 mg/L). Arsenic levels in Ropar and Anandpur Sahib were 0.09 and 0.068 mg/L, respectively. Cadmium was highest in Nurpur Bedi (0.041 mg/L). Morinda had the highest selenium concentration (0.0038 mg/L). Lead was detected across all blocks, peaking in Chamkaur Sahib (2.176 mg/L). The HQ exceeded unity in nearly all areas, indicating significant health risks from aluminium, arsenic, and lead. The hazard index was highest in Nurpur Bedi (2.66) for adults. Incremental Life Cancer Risk (ILCR) values indicated a high cancer risk from arsenic, chromium, and lead across all blocks. One-way analysis of variance revealed significant differences among Fe, As, and Al concentrations (p &amp;lt; 0.05). The findings underscore the need for targeted treatment technologies and policies to mitigate heavy metal contamination and its health impacts in Punjab.

Appraisal of Characterization and Adsorption Isotherm in the Bioremediation of Cu and Zn Ions from Aqueous Solutions Exploiting Unmodified Corn and Coconut Husk

Environment is contaminated by heavymetals has emerged as a substantial globaly. Conventional remediation methods have proven inadequate and costly in addressing this issue. Hence, there is a pressing need to discover bio-remediation as a cost effective, effectual, and environmentally, a substitute for heavymetal removal. This work investigates the adsorption behaviour of Corn Husk (CH) and Coconut Husk (CCH), an inexpensive adsorbent, towards Cu and Zn ions for potential application in wastewater treatment. The physico-chemical variables of unmodified CH and CCH were appraised, and batch experimental methods were employed to study variables like pH, contact time, size of particle, and preliminary content of metals. The impact of solution pH on metals uptake by the adsorbent was investigated on the pH range of 3 to 8, revealing optimal removal efficiencies at pH 6 for Cu and pH 5 for Zn. Equilibrium adsorption times were determined to be 80 minutes for Cu and 60 minutes for Zn ions onto CH and CCH. adsorption volumes is conforming to mono-layer coverage, attained from the Langmuir plots were 4.792 mg/g and 4.594 mg/g respectively for Cu and Zn metals onto the CH and 4.771 mg/g and 4.400 mg/g for their adsorption onto CCH. Experimental values were confirmed to the Langmuir model and Freundlich model, with the Langmuir model providing the best fit. The CH based adsorbent was generally found to have an increased capacity of adsorption of the metal contents than Coconut husk (CCH). These findings underscore the strength of Corn husk as an active adsorbent to extract cationic heavymetal contents from industrial effluents.

High metal-loaded sub-nanocluster catalyst enhanced Fenton-like reaction activity for emerging contaminants degradation by generating high-valent copper

High-valent copper (Cu(III)) species are crucial intermediates in CH bond functionalization within both the biological and biomimetic processes, facilitated by copper enzymes and stabilized by multicopper oxidases. Herein, a nitrogen-doped copper sub-nanocluster catalyst (SNC) featured a high metal content (29.1 wt%) and uniform Cu distribution was synthesized by carbonizing the nanosheet-like metal–organic framework (MOF), enhancing bisphenol A degradation by activating peroxymonosulfate (PMS) to generate Cu(III). The degradation performance of the SNC outperformed the catalyst carbonized with the bulk-like MOF and matched the reported single-atom catalysts counterparts. Nitrogen doping decreased the electrons of Cu3d orbital, enhancing its bonding with the oxygen atom within the PMS molecule, thus promoting Cu(III) generation. The Cu-SNC/PMS system also showed robust resistance against anions, pH changes, and diverse water matrices. Importantly, it can selectively degrade electron-rich pollutants through oxygen atom transfer by Cu(III). This study provided new perspectives into SNC preparation, the controlled formation of high-valent metal species, and their role in Fenton-like reactions for pollutants degradation.

Gradient composites Al2O3-Ni obtained via the CSC technique in a magnetic field - microstructure and mechanical properties

This article presents the formation of composite microstructures by combining two established concepts: centrifugal slip casting and the utilization of a magnetic field to control the distribution of magnetic particles. The integration of these methodologies offers the potential to create zones within the composite with distinct hardness values. The study introduces a novel method for fabricating ceramic-metal composites, with a key focus on determining the feasibility of manipulating the location of the metallic phase using a magnetic field. Through this innovative approach, the research aims to produce composite hollow cylinders with a gradient distribution of metallic particles. The relative density of the composites was 97 %. The hardness values for the samples range from 970 HV to 2700 HV, displaying variability based on the metallic phase content within the material. The compressive strength for Al2O3-Ni samples was equal to 128.92 MPa. The Al2O3 grains in zone III after the sintering process have an average size of 1.27 ± 0.68 µm. The Al2O3-Ni composites indicate a smaller heat capacity of the material compared to pure Al2O3 samples.

Mapping radial abundance gradients with Gaia -ESO open clusters. Evidence of recent gas accretion in the Milky Way disk

Recent evidence from spectroscopic surveys points towards the presence of a metal-poor, young stellar population in the low-alpha , chemically thin disk. In this context, the investigation of the spatial distribution and time evolution of precise, unbiased abundances is fundamental to disentangle the scenarios of formation and evolution of the Galaxy. We study the evolution of abundance gradients in the Milky Way by taking advantage of a large sample of open star clusters, which are among the best tracers for this purpose. In particular, we used data from the last release of the Gaia -ESO survey. We performed a careful selection of open cluster member stars, excluding those members that may be affected by biases in spectral analysis. We compared the cleaned open cluster sample with detailed chemical evolution models for the Milky Way, using well-tested stellar yields and prescription for radial migration. We tested different scenarios of Galaxy evolution to explain the data, namely, the two-infall and the three-infall frameworks, which suggest the chemical thin disk is formed by one or two subsequent gas accretion episodes, respectively. With the performed selection in cluster member stars, we still find a metallicity decrease between intermediate-age ($1&lt;$ Age/Gyr $&lt;3$) and young (Age $&lt;1$ Gyr) open clusters. This decrease cannot be explained in the context of the two-infall scenario, even by accounting for the effect of migration and yield prescriptions. The three-infall framework, with its late gas accretion in the last 3 Gyr, is able to explain the low metallic content in young clusters. However, we have invoked a milder metal dilution for this gas infall episode relative to previous findings. To explain the observed low metallic content in young clusters, we propose that a late gas accretion episode triggering a metal dilution would have taken place, extending the framework of the three-infall model for the first time to the entire Galactic disk.

A study based on high-density data examines the current status and evolution laws of heavy metal environmental capacity in the Bardawu area of the Qinghai-Tibet Plateau

As the first ladder of China, the Qinghai-Tibet Plateau has always been known as the “roof of the world”. Its environmental carrying capacity can be estimated more accurately than other regions because of its harsh natural environment, low population density, limited industrial and agricultural development, and low human activities. However, the current ecological risks of Co and threshold research are limited, and there is a lack of awareness of W’s environmental risks. Hence, this study assessed the ecological support potential of the Bardawu region within Dulan County, Qinghai Province, using 7373 soil specimens, determined regional soil baseline measures, and applied the substance equilibrium linear technique along with the ecological aggregate indicator technique to examine the heavy metal content of the soil. A comprehensive evaluation of the environmental capacity and health risks was conducted to provide a reference for pastoral planning. The findings indicated that the cumulative static ecological capacity of the six trace heavy elements in the soil was ranked as follows: Cr > Li > Ni > Cu > W > Co, with W and Co positioned as the final pair. The remaining areas with a high environmental capacity were predominantly found in the study zone. The central sector exhibited diminished environmental capacity in the southwest and northeast and presented a contamination hazard. Land use, soil type, and geological type considerably affected the six elements in the study area at the p < 0.05. The Bardawu region’s mean comprehensive index of soil environmental capacity was 0.98, indicating an intermediate level of environmental capacity and a moderate health risk. This study focuses on the geological context and influence of pastoral activities on the soil, augments the distribution of various elements across the Tibetan Plateau, and suggests preliminary soil governance strategies. The findings of this study lay the groundwork for soil environmental conservation and remediation efforts in highland regions.

Unveiling the quasar main sequence: illuminating the complexity of active galactic nuclei and their evolution

The Eigenvector 1 schema, or the main sequence of quasars, was introduced as an analogous scheme to the HR diagram that would allow us to understand the more complex, extended sources - active galactic nuclei (AGNs) that harbor accreting supermassive black holes. The study has spanned more than three decades and has advanced our knowledge of the diversity of Type-1 AGNs from both observational and theoretical aspects. The quasar main sequence, in its simplest form, is the plane between the FWHM of the broad Hβ emission line and the strength of the optical Fe ii emission to the Hβ. While the former allows the estimation of the black hole mass, the latter enables direct measurement of the metal content and traces the accretion rate of the AGN. Together, they allow us to track the evolution of AGN in terms of the activity of the central nuclei, its effect on the line-emitting regions surrounding the AGN, and their diversity making them suitable distance indicators to study the expansion of our Universe. This mini-review aims to provide (i) a brief history leading up to the present day in the study of the quasar main sequence, (ii) introduce us to the many possibilities to study AGNs with the main sequence as a guiding tool, and (iii) highlight some recent, exciting lines of researches at the frontier of this ever-growing field.

Study of the effect of feeding Tenebrio molitor larvae during their rearing on their growth, nutritional profile, value and safety of the produced flour

Science and food industry must strive to ensure and improve edible insect's benefits, and especially their safety and nutritional value. This study investigated how various food substrates used in the rearing of Tenebrio molitor larvae influence their growth, the safety of the larvae, and the nutritional quality of the resulting flour. The main findings indicate that all samples showed significant differences in their nutritional profile, larval characteristics, and heavy metal content. Regarding the content of protein, fat and fiber it ranges from 44.1 to 51.8 %, 28.6–34.8 % and 10.5–14.9 %, respectively. These results suggest that insect diet is a very crucial parameter that can affect all that factors and must be taken into account, especially when they are intended as raw materials to be used for food production.