The contamination of the Lower Danube Basin with trace elements has been the subject of intense study in recent years, with several pollution indices being employed for the assessment of water, soil, and sediment quality. Most pollution indices are calculated by comparing the measured concentration to a reference value, with different values from various sources being used. In this study, the threshold values for trace elements (As, Cd, Cu, Hg, Ni, Pb, and Zn) in Romania were selected based on the median of their concentration in stream sediment from 167 locations, which were carefully selected to be far from contamination sources. The threshold values were established based on a calculation starting from the geochemical concentration presented in the Geochemical Atlas of Romania (scale: 1:3,000,000, developed in 2006 by a collaborative Romanian-German team). By using these thresholds, pollution indices were calculated for nine sampling locations, from which suspended sediment, bottom sediment, and active floodplain sediment samples were collected and analyzed in an accredited laboratory. Most of the selected thresholds were found to be below the limits for sediments established by Romanian legislation, except for Cr and Ni, the higher values of which are consistent with the specific geological background of the country and the broader Balkan region.

This study introduces novel experimental systems that facilitate the nucleation, growth, aggregation, and agglomeration of ionic salt solutions, leading to structurally and functionally distinctive crystal formations. Through evaporative crystallization in hanging drops—including layered binary solutions—a range of macroscopic agglomerates were produced, such as hollow spheroidal NaCl/NiSO₄ structures, octahedral NaCl films, pentagonally arranged CdSO₄ spherulites, and NH₄Cl dendritic shells. Additionally, NaCl spheroids were used as templates to fabricate carbon-based morphologies and colloidal photonic crystals with convex or concave geometries, which were subsequently analyzed optically. The study reveals that crystallization and self-assembly, whether independently or synergistically applied, can yield complex architectures with potential applications in advanced device manufacturing beyond conventional processing methods.

Composites were obtained by using a commercial bicomponent epoxy resin (containing Al₂O₃ and SiO₂) and cubic BN (cBN) (0–50 wt.%). Two preparation methods were used: (a) the cBN powder was first mixed with the resin base and further with the hardener, and (b) the cBN powder was first mixed with hardener and afterwards with the resin base. Both methods show a similar enhancement trend in the thermal conductivity from 0.77 W/mK in the resin without additive to 1 and 1.5 W/mK in the ones filled with 30 and 50 wt.% cBN, respectively. A reasonable decrease in bending strength from 74 for 0 wt.% cBN to 70 or 64 MPa for 30 wt.% cBN added by method (a) or (b), respectively, occurs. The bending strain at breakage decreased from 5.58% to 2.65 or 3.78%. High sensitivity vs. processing was also found for electrical properties measured for frequencies of 1–10⁷ Hz. An increasing amount of cBN decreased the room temperature conductivity, dielectric constant, and dielectric loss tangent and modified the shape of the curves vs. frequency. However, in samples with 30 wt.% or more of cBN, a partial recovery to a high insulating state was observed.