Compounds, Volume 4, Issue 3 (September 2024) – 10 articles

To investigate how hydrodynamic cavitation (HC) affects the adsorption of sodium oleate (NaOl) on diaspore and kaolinite surfaces, a comparative study on NaOl adsorption was conducted under different conditions. The flotation and separation of the minerals were also examined with and without HC pretreatment of NaOl. The results show that short-term HC pretreatment of NaOl solutions did not induce a measurable change in the chemical structure of NaOl, but produced micro-nanobubbles (MNBs) and resulted in decreases in the surface tension and viscosity of liquids. When MNBs interacted with minerals, their anchor on solids could affect the contact angles, zeta potentials, and surface NaOl adsorption toward minerals. At low NaOl concentrations, the presence of MNBs reduced the NaOl adsorption capacity and particles’ zeta potential while increasing the minerals’ contact angle. At higher NaOl concentrations, the presence of MNBs promoted NaOl adsorption, further increased the minerals’ contact angle, and further decreases the particles’ zeta potential. Additionally, the flotation and separation of minerals can be enhanced at low NaOl concentrations, largely due to the enhanced bubble mineralization through the selective surface-anchoring of MNBs on diaspore. However, the separation efficiency might deteriorate at high NaOl concentrations, though the presence of MNBs amplified the divergences in minerals’ surface wettability and zeta potentials. Full article

Article presents a comparison of surface structure study methods, such as atomic force microscopy, scanning and transition electron microscopy in terms of metallic materials 3D-printed using the laser powder bed fusion technique. The main features, advantages, disadvantages of atomic force microscopy as a research method for the LPBF synthesized samples are discussed in the context of hard magnetic material, specifically Nd-Fe-B. The ability to provide qualitative grain structure analysis with the high-resolution images of atomic force microscopy is comprehensively studied. For confirmation good applicability of the above-mentioned method for LPBF sample analysis images of a magnetic domain structure obtained via atomic force microscopy are presented. Thus, the applicability of atomic force microscopy to the quality microstructural investigation of metallic materials obtained by LPBF is demonstrated. Full article

In the present study, XRD, SEM/EDS, Raman, EMR/EPR spectroscopy, and vibrating sample magnetometry (VSM) were used to analyze the reduction of hematite by the carbonization products of waste activated sludge (WAS) at 500–1000 °C. The reduction process includes the following steps: α-Fe₂O₃ → Fe₂O₃ + Fe₃O₄ (T_tr~500 °C) → Fe₃O₄ (T_tr~600–700 °C) → FeO → Fe_amorph. (T_tr~1000 °C). The prevalence of certain phase compositions at different hematite reduction temperatures makes it possible to predict the areas viable for the application of reduced oxides: adsorbents (after T_tr~500 °C) → soft ferromagnetic materials (after T_tr~600–700 °C) → electrically engineered amorphous iron (after T_tr~1000 °C). Full article

Zinc oxide (ZnO) is one of the most versatile semiconductor materials with many potential applications. Understanding the interactions between the surface chemistry of ZnO along with its physico-chemical properties are essential for the development of ZnO as a robust photocatalyst for the removal of aqueous pollutants. We report on the fabrication of nanoparticle-like porous ZnO films and the correlation between the fabrication process parameters, particle size, surface oxygen vacancies (SOV), photoluminescence and photocatalytic performance. The synthesis route is unique, as highly porous zinc layers with nanoscale grains were first grown via magnetron sputtering, a vacuum-based technique, and subsequently annealed at temperatures of 400 °C, 600 °C and 800 °C in oxygen flow to oxidise them to zinc oxide (ZnO) while maintaining their porosity. Our results show that as the annealing temperature increases, nanoparticle agglomeration increases, and thus there is a decrease in the active sites for the photocatalytic reaction. However, for selected samples the annealing leads to an increase of the photocatalytic efficiency, which we explain based on the analysis of defects in the material, based on photoluminescence (PL). PL analysis showed that in the material the transition between the conduction band and the oxygen vacancy is responsible for the green emission centered at 525 nm, but the photocatalytic activity correlated best with surface states—related emission. Full article

This study aims at investigating the chemical composition of root, stem and leaf essential oils from Ivorian Synedrella nodiflora, with the root oil being described for the first time. Sixty, fifty-one and forty-nine constituents were, respectively identified in the root, stem and leaf oils using a combination of GC(RI), GC-MS and ¹³C-NMR analyses. They accounted for 95.6–97.3%, 92.6–97.6% and 93.3–98.8% of the total composition, respectively. The main components of the root oil samples were γ-curcumene, (E)-β-caryophyllene, α-curcumene and curcuphenyl acetate. Three stem oil samples (S1, S2a, S3) were dominated by myrcene and limonene, while the most abundant components of sample S2b were thymol, germacrene D and β-elemene. (E)-β-caryophyllene and germacrene D were the major compounds of the leaf oil. Hierarchical cluster and principal component statistical analyses were performed and confirmed that the location does not influence the chemical composition. Group I consisted of the seven leaf oil samples, group II consisted of four stem oil samples and group III consisted of three root oil samples. The root oil composition differed considerably from the stem and leaf oil composition due to the presence of curcumene derivatives as major constituents. The leaf oil showed significant amounts of (E)-β-caryophyllene and germacrene D, while the stem oil stood out for its high myrcene, limonene and thymol contents. Full article

Zinc oxide (ZnO) nanoparticles are widely recognized for their distinctive properties and versatile applications across diverse technological domains. However, traditional methods of synthesizing ZnO nanoparticles are characterized by environmental incompatibility, high costs, and the necessity for precise process control to attain the intended particle dimensions and morphology. The present study utilized a chives extract as a sustainable and eco-friendly fuel in the solution combustion synthesized (SCS) process to produce ZnO nanoparticles. The investigation encompassed an analysis of the impact of the fuel-to-oxidizer (F/O) ratio on the synthesized ZnO nanoparticles’ size, morphology, and crystallinity. X-ray diffraction (XRD) results showed that the particle’s crystallite size increased significantly from 12 nm to 42 nm after decreasing the F/O ratio. Furthermore, electron microscopic imagery and FTIR spectroscopy outcomes indicated that modifications in the F/O ratio significantly influenced the SCS process parameters, forming particles with diverse morphologies, including spherical, pyramid-like, hexagonal, and hexagonal plate-like shapes. This research presents a straightforward, cost-efficient, and environmentally sustainable approach for producing ZnO nanoparticles with diverse morphologies, presenting a broad potential for various applications. Full article

Cardiovascular diseases (CVDs) are a global health problem. The mortality associated with them is one of the highest. Essentially, CVDs occur when the heart or blood vessels are damaged. Oxidative stress is an imbalance between the production of reactive oxygen species (free radicals) and antioxidant defenses. Increased production of reactive oxygen species can cause cardiac and vascular injuries, leading to CVDs. Antioxidant therapy has been shown to have beneficial effects on CVDs. Plants are a rich source of bioactive antioxidants on our planet. Several classes of these compounds have been identified. Among them, carotenoids and phenolic compounds are the most potent antioxidants. This review summarizes the role of some carotenoids (a/β-carotene, lycopene and lutein), polyphenols such as phenolic acids (caffeic, p-coumaric, ferulic and chlorogenic acids), flavonoids (quercetin, kaempferol and epigallocatechin gallate), and hydroxytyrosol in mitigating CVDs by studying their biological antioxidant mechanisms. Through detailed analysis, we aim to provide a deeper understanding of how these natural compounds can be integrated into cardiovascular health strategies to help reduce the overall burden of CVD. Full article

The electrodeposition of copper (Cu), silver (Ag), and their alloys has been a subject of interest since the 19th century. Primarily due to their exceptional features such as good mechanical hardness and electrical conductivity, high resistance to corrosion, and electromigration, Cu–Ag electrodeposits continue to be investigated and developed to improve their properties for different applications. This paper reviews the state of the art in the field of electroplated Cu–Ag alloys in an aqueous solution, with particular emphasis on the observed properties and variety of electrochemical processes used to produce high-quality materials. Moreover, this review paper focuses on the experimental conditions employed for Cu–Ag electrodeposition, intending to understand the basis and manipulate the processes to obtain coatings with superior characteristics and for attractive usage. Finally, the most trending applications of these coatings are discussed depending on different parameters of electrodeposition to provide prospects for potential research. Full article

Dental erosion represents the gradual and irreversible depletion of dental hard tissues due to a chemical process, independent of bacterial influence. It has emerged as a notable clinical concern in recent years, primarily attributed to substantial lifestyle shifts resulting in the heightened intake and frequency of acid-containing foods and beverages. Apart from the extrinsic erosive agents derived from external sources, such as dietary habits or medication, intrinsic erosive agents may exist due to pathological reasons with the contents of the stomach including gastric juice, mainly composed of hydrochloric acid, being their sole source. Currently, bioactive materials are used in various forms for the prevention of dental erosion. Such materials include, among others, bioactive glasses (BAGs). BAGs are a type of glass that, when in contact with biological fluids, can elicit a specific biological response. When they come into contact with bodily fluids, they can initiate a series of processes, including the formation of a hydroxyapatite layer on the glass surface. This bioactivity is particularly advantageous in medical and dental applications, where BAGs are used for bone regeneration, tissue repair, and dental restorative or preventive techniques. The aim of this literature review was to analyze and discuss the role of BAGs in protecting the tooth structures from dental erosion. The analysis of the existing literature regarding this topic indicated that the use of BAGs in preventive treatments against tooth erosion can be useful in dental practice. Further clinical evidence is necessary to confirm the effectiveness of the particular preventive measures. Full article