Ramona Bianca Sonher

The properties of solution-derived nickel oxide (NiO) thin films are strongly influenced by precursor chemistry and post-deposition thermal treatment. In this work, NiO thin films were deposited on indium tin oxide (ITO)-coated glass substrates by chemical solution deposition using a spin-coating process. A 0.6 M nickel acetylacetonate-derived precursor solution prepared in a methanol–propionic acid solvent system was used as the starting solution. The films were thermally treated at 600 °C under continuous oxygen flow, with annealing holding times of 2, 4, and 6 h, to evaluate the effect of thermal-treatment duration on phase formation, surface morphology, and electrochemical redox behavior. Thermal and infrared analyses confirmed precursor decomposition and the formation of nickel–oxygen bonding after thermal conversion. X-ray diffraction confirmed the formation of single-phase cubic NiO at all holding times, while quantitative peak analysis indicated a modest increase in crystallite size from 12.4 to 13.9 nm with prolonged annealing. Atomic force microscopy revealed continuous and homogeneous film surfaces, with low root-mean-square roughness values in the range of 2.5–2.7 nm. Cyclic voltammetry in a LiClO₄/propylene carbonate electrolyte showed a reversible redox response associated with the Ni²⁺/Ni³⁺ transition, accompanied by visible switching between bleached and colored states. The results indicate that annealing holding time affects the structural and morphological characteristics of spin-coated NiO thin films, while the electrochemical measurements confirm reversible redox activity in the investigated sample. These findings provide a processing-oriented basis for evaluating thermal-treatment conditions in solution-derived NiO films intended for electrochemical and optical modulation applications.

Soil contamination by heavy metals is a significant sustainability and ecological issue, impacting on the health of ecosystems and groundwater. This study assessed the efficacy of malic acid as a biodegradable and environmentally benign agent for the remediation of soils contaminated with cadmium, chromium, copper, and zinc. Two soils with contrasting textures were treated with a 10% malic acid solution at solid/liquid ratios of 1:5 and 1:10 for contact times of 2, 4, 6, and 8 h. The extraction efficiency varied depending on metal type, soil texture, and washing conditions. Cadmium removal ranged from 26% to 55%, zinc removal ranged from 10% to 25%, while copper showed variable extraction (5–45%) depending on initial soil concentration. Chromium exhibited the highest removal efficiency (30–90%), quantified as total chromium; however, the absence of speciation analysis (Cr(III)/Cr(VI)) represents a key limitation and may affect the interpretation of the removal performance. FTIR and UV–Vis analyses confirmed the formation of metal–carboxylate complexes and changes in soil functional groups during the washing process. In addition, significant mobilization of nitrogen and potassium was observed, whereas phosphorus remained relatively stable. The results highlight the influence of soil texture and multi-metal interactions on malic acid washing efficiency and provide a laboratory-scale environmental assessment of malic acid as a sustainable remediation alternative for soil remediation, while emphasizing the need for further evaluation regarding chromium speciation and post-treatment soil quality and sustainability impacts.

This work presents the elaboration and photocatalytic evaluation of perovskite–graphene LaMnO3–rGO (LMO–rGO) composite thin films, synthesized via a novel eco-friendly chemical solution deposition process. The thermal decomposition behavior of the precursor powder, obtained by drying the precursor solution, was investigated by thermogravimetry coupled with quadrupole mass spectrometry and differential thermal analysis, revealing a multi-step decomposition mechanism with pure LMO phase crystallization initiating near ~500 °C. Thin films were fabricated by spin-coating deposition of the precursor solution onto glass and SrTiO3 substrates, followed by controlled pyrolysis and crystallization. The structural and morphological properties of the films were characterized by X-ray diffraction, atomic force microscopy, and transmission electron microscopy, confirming the formation of well-crystallized, compact, and adherent films with moderate surface roughness. The photocatalytic performance was evaluated through methylene blue degradation under light irradiation, demonstrating efficient and progressive dye decomposition attributed to the synergistic effect of rGO incorporation, which enhances charge carrier separation and suppresses electron–hole recombination. The thin film geometry further offers practical advantages in terms of easy recovery, reusability, and minimal material loss, making LMO–rGO a promising candidate for aquatic environmental remediation applications.

The synthesis of ultra‐small core–shell nanoparticles offers promising pathways for enhancing the performance of superconducting films. This study presents the solvothermal synthesis and characterization of α‐Fe ₂ O ₃ /Ag core–shell nanoparticles, designed as effective pinning centers in YBa ₂ Cu ₃ O _7‐x (YBCO) superconducting films. The nanoparticles, below 10 nm diameters, were synthesized via controlled decomposition of iron (III) nitrate and silver nitrate in triethylene glycol, which served as both solvent and stabilizing agent. Transmission electron microscopy confirmed the uniform core–shell structure, while X‐ray diffraction validated the crystalline phases of the Fe ₂ O ₃ core and Ag shell. Magnetic measurements revealed the influence of magnetic nature of nanoparticles, which is critical for enhancing vortex pinning in YBCO films. Energy‐dispersive X‐ray spectroscopy confirmed the elemental composition and chemical states. These ultra‐small α‐Fe ₂ O ₃ /Ag nanoparticles show potential as tailored inclusions to improve critical current densities in YBCO superconducting films by enhancing flux pinning efficiency.

This study provides a comprehensive chemical assessment of groundwater quality from 37 domestic wells in the rural village of Hodăi-Boian, Ceanu Mare commune, Romania, with emphasis on contamination risks arising from anthropogenic activities. Key water quality parameters—nitrites(NO₂⁻), nitrates(NO₃⁻), ammonium(NH₄⁺), pH, turbidity, and electrical conductivity(EC)—were determined according to standardized analytical protocols and compared against Romanian and European regulatory thresholds. Exceedances of the maximum admissible concentration for NO₂⁻ were detected in seven wells, indicating recent contamination events likely linked to the proximity of animal shelters and latrines. NO₃⁻ and NH₄⁺ concentrations remained below legal limits, although elevated NH₄⁺ levels signal persistent microbiological activity. The findings revealed pronounced mineralization and frequent surpassing of conductivity limits, while pH values below 7.0 in selected wells suggested active organic fermentation processes. Water temperature ranged from 11–13 °C, confirming the shallow aquifer character. Correlative analysis demonstrated strong associations between well proximity to pollution sources, livestock density, and water quality deterioration. The results underscore the necessity of regular water quality monitoring, rigorous enforcement of protective distances, and technical improvements to well construction. Strengthening public health education and upgrading sanitation infrastructure are imperative to mitigate health risks and safeguard the safety of groundwater resources in vulnerable rural environments.

This study provides a comparative analysis of agricultural practices, water resource management, and environmental risks in two rural communes of Transylvania, Romania—Ceanu Mare (Cluj County) and Chețani (Mureș County). Data were collected in June 2025 through structured questionnaires administered to 430 households in Ceanu Mare and 184 households in Chețani, representing over 30% and 20% of the total households, respectively. The research examines the structure of agricultural activity, use of fertilizers and pesticides, irrigation methods, and the local perception of pollution and subsidy programs. Both communes exhibit small-scale, household-based agriculture, but notable differences exist: Ceanu Mare demonstrates higher use of chemical inputs and environmental awareness, while Chețani relies more on organic fertilizers and private wells for irrigation. In addition to survey-based data, the study incorporates direct chemical analysis of household well water, assessing concentrations of nitrate (NO₃⁻), nitrite (NO₂⁻), ammonium (NH₄⁺), and pH levels as indicators of groundwater quality and public health risk. The results reveal that NO₃⁻ remained below the 50 mg/L standard in all wells, while NO₂⁻ approached or slightly exceeded 0.50 mg/L in a few Ceanu Mare villages, underscoring the vulnerability of shallow wells to diffuse agricultural inputs and sanitation deficits. The study also characterizes the main agrochemical compounds used and discusses their potential impacts on water and soil quality, emphasizing nitrate leaching, phosphate runoff, and the persistence of pesticide residues as major risks. These findings underscore the necessity of integrated management strategies, regular monitoring of groundwater quality, and targeted policy interventions to ensure sustainable rural development and environmental protection in similar Central and Eastern European contexts.

This study provides a comprehensive assessment of water infrastructure, consumption management, and educational practices across all public pre-university educational institutions in Cluj County, Romania. The research addresses the increasingly urgent imperative of sustainable water resource management within educational settings, in alignment with both European and global priorities. This analysis is based on a comprehensive data set collected in June 2025 from all 392 public pre-university educational institutions in Cluj County, encompassing both urban and rural areas, all educational levels, and all types of institutions. Data was gathered using a standardized questionnaire, which was validated with the official support of the Cluj County School Inspectorate. The quantitative analysis highlights significant urban–rural disparities: 95.566% of urban institutions are equipped with modern meters and connected to public water networks, compared to only 68.254% in rural areas. Water consumption monitoring relies predominantly on invoice data (69.388%), while the adoption of advanced monitoring technologies remains limited. Reported water losses are minimal (1.531%), and only 0.765% of educational institutions have indicated non-compliance issues related to water quality in the past three years. Educational measures and water-saving awareness campaigns are present in 65.562% of institutions, yet only about one-third (32.908%) have implemented dedicated projects or partnerships. The financial analysis reveals that 90.487% of annual water and sewerage costs are borne by urban institutions. The study highlights both the progress achieved and the persistent challenges, particularly in rural infrastructure and the expansion of educational interventions. The results provide a robust empirical basis for informing regional and national policies, supporting targeted investments, integrated educational programs, and continuous monitoring to ensure sustainable water resource management in the Romanian educational system.

The role of diethanolamine (DEA) as a chelating agent was investigated in a fluorine-free precursor solution for the growth of superconducting YBa₂Cu₃O₇ (YBCO) thin films via chemical solution deposition. Infrared spectroscopy and thermal analyses were employed to elucidate the interactions between the chelating agent and propionate-based coating solution. The physical properties of the as-obtained YBCO films were investigated to assess the effect of DEA addition on film growth. Special emphasis was placed on the determination of superconducting transport properties. These have been investigated in wide magnetic field (0–18 T) and temperature (4.5–77 K) ranges to account for various possible application scenarios. The 100 nm thick YBCO film deposited on a (001) SrTiO₃ single-crystal substrate exhibited a critical current density of 4 MA cm⁻² at 77 K in self-field.