This study closely analyzes the water quality dynamics of Teceu Lake, situated in a Natura 2000 protected area in Romania. The research investigates seasonal variations and interconnections with groundwater, assessing various ecological impacts. The main physico-chemical indicators of water, such as electrical conductivity (EC), dissolved oxygen (DO), oxygen saturation (OS), temperature, pH, turbidity, ammonium concentration (NH₄⁺), nitrates (NO₃⁻), nitrites (NO₂⁻), orthophosphates (PO₄³⁻), water hardness, alkalinity (A), and chlorides (Cl⁻), were measured over the January–December 2022 period. Metal concentrations for both major metals (Na, K, Ca, Mg, Al) and trace metals (Li, Ga, Fe, Mn, Pb, Cu, Zn, Ni, Ti, Mo, Sr, Ba) were assessed. The evolution of the physico-chemical indicators revealed an increase in nutrient compounds (ammonium and phosphates) during the spring and autumn months. The EC values ranged from 180–444 μS/cm for the lake and 1575–2480 μS/cm for groundwater. The pH values (7.12–7.96) indicated a slightly alkaline environment. DO levels (6.79–11.21 mg/L) indicated good water quality. Chlorides exceeded levels in drinking water in some instances. Water hardness varied due to pH, temperature, and atmospheric pressure. Metal composition revealed diverse levels of aluminum, barium, nickel, copper, zinc, and manganese, which carries implications for environmental and human health. The water quality index (WQI) score, which is based on major ions, indicated that 93% of the groundwater samples were classified as excellent and good for drinking. WQI, based on the main physico-chemical indicators, revealed that 79.17% of the Teceu Lake-water samples and 41.66% of the groundwater samples gathered were classified as good quality; the difference indicated poor quality, especially in autumn. Q- and R-mode cluster analyses revealed distinct clusters for seasonal months and sampling points, suggesting shared sources and geological influences. Notable connections between physico-chemical indicators and metal content were identified, emphasizing the need for a tailored conservation strategy. Correlation analyses highlighted both positive and negative relationships between metal pairs. Understanding these parameters is vital for water resource management and preserving biodiversity in the region. The results of this study are important for monitoring pollution in Lake Teceu and might prompt local communities and authorities to take measures to reduce and prevent pollution.

The structural, morphological, and optical properties of Ni²⁺ ions substitution in CoCr₂O₄ matrix as ceramic pigments were investigated. The thermal decomposition of the dried gel was performed aiming to understand the mass changes during annealing. The X-ray diffraction (XRD) studies reveal a spinel-type Face–Centered Cubic structure and a secondary Cr₂O₃ phase when x ≤ 0.75 and a Body–Centered Tetragonal structure when x = 1. Fourier Transform Infrared Spectroscopy (FT–IR) indicated two strong absorption bands corresponding to the metal–oxygen stretching from tetrahedral and octahedral sites, characteristic of spinel structure. Ultraviolet–Visible (UV–Vis) spectra exhibited the electronic transitions of the Cr²⁺ Cr³⁺ and Ni²⁺ ions. From the UV–Vis data, the CIE color coordinates, (x, y) of the pigments were evaluated. The morphology was examined by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) showing the agglomeration behavior of the particles. The stability, coloring properties and potential ceramic applications of studied pigments were tested by their incorporation in matte and glossy tile glazes followed by the application of obtained glazes on ceramic tiles. This study highlights the change in pigment color (from turquoise to a yellowish green) with Ni²⁺ ions substitution in the CoCr₂O₄ spinel matrix.

The present study introduces a monitoring initiative focused on the quality of groundwater in the Piatra locality, situated in the North-West region of Romania. This paper employs an evaluation of 21 physico-chemical parameters, encompassing factors such as electrical conductivity, pH, chemical oxygen demand, turbidity, total hardness, NH₄⁺, NO₃⁻, Cl⁻, PO₄³⁻, Li, Na, K, Ca, Mg, Ba, Sr, Al, Fe, Mn, Sn, and Ti. Additionally, it examines five heavy metals (Cr, Cu, Ni, Pb, and Zn) and arsenic in water sourced from six distinct private wells. Each well, with its characteristics, serves as a unique drinking water source. The assessment encompassed the evaluation of pollution levels, quality status, and risk factors for all drinking water sources, utilizing pollution, quality, and risk indices. The aim of this study was to establish the level of toxicity in water, assess its impact on human health, and disseminate information to the public about the appropriate utilization of individual water sources. The results indicated a general contamination with chloride, ammonium, manganese, chromium, and iron. Human health risk assessment indices revealed that the consumption of studied waters presented non-carcinogenic risks associated with Cr for adults and with Cr, As, Pb, and Cu for children for some of the groundwater sources. The water quality index (WQI) categorizes the samples as possessing excellent and good quality. This research represents one of the initial endeavors to assess the groundwater source quality in connection with the potential human health risks posed by the metals studied within the protected area of the Tisa River Basin.

To address tooth enamel demineralization resulting from factors such as acid erosion, abrasion, and chronic illness treatments, it is important to develop effective daily dental care products promoting enamel preservation and surface remineralization. This study focused on formulating four toothpastes, each containing calcined synthetic hydroxyapatite (HAP) in distinct compositions, each at 4%, along with 1.3% birch extract. Substitution elements were introduced within the HAP structure to enhance enamel remineralization. The efficacy of each toothpaste formulation was evaluated for repairing enamel and for establishing the dynamic of the remineralization. This was performed by using an in vitro assessment of artificially demineralized enamel slices. The structural HAP features explored by XRD and enamel surface quality by AFM revealed notable restorative properties of these toothpastes. Topographic images and the self-assembly of HAP nanoparticles into thin films on enamel surfaces showcased the formulations’ effectiveness. Surface roughness was evaluated through statistical analysis using one-way ANOVA followed by post-test Bonferroni’s multiple comparison test with a p value < 0.05 significance setting. Remarkably, enamel nanostructure normalization was observed within a short 10-day period of toothpaste treatment. Optimal remineralization for all toothpastes was reached after about 30 days of treatment. These toothpastes containing birch extract also have a dual function of mineralizing enamel while simultaneously promoting enamel health and restoration.

This research work aims to develop functional toothpastes with combined enamel remineralization and antibacterial effects using nano-hydroxyapatites (nHAPs) and birch extract. Eleven toothpastes (notated as P1–P11) were designed featuring different concentrations of birch extract and a constant concentration of pure nHAPs or substituted nHAPs (HAP-5%Zn, HAP-0.23%Mg-3.9%Zn-2%Si-10%Sr, and HAP-2.5%Mg-2.9%Si-1.34%Zn). In vitro assessments involved treating artificially demineralized enamel slices and analyzing surface repair and remineralization using Atomic Force Microscopy (AFM). The Agar Disk Diffusion method was used to measure antibacterial activity against Enterococcus faecalis, Escherichia coli, Porphyromonas gingivalis, Streptococcus mutans, and Staphylococcus aureus. Topographic images of enamel structure and surface roughness, as well as the ability of nHAP nanoparticles to form self-assembled layers, revealed excellent restorative properties of the tested toothpastes, with enamel nanostructure normalization occurring as soon as 10 days after treatment. The outcomes highlighted enamel morphology improvements due to the toothpaste treatment also having various efficacious antibacterial effects. Promising results were obtained using P5 toothpaste, containing HAP-5%Zn (3.4%) and birch extract (1.3%), indicating notable remineralization and good antibacterial properties. This study represents a significant advancement in oral care by introducing toothpaste formulations that simultaneously promote enamel health through effective remineralization and bacterial inhibition.