Acta Chimica Slovenica最新文献

In this paper, activated carbons obtained from walnut shells were used as adsorbents to remove nitrite ions from aqueous solutions. The novel adsorbent was obtained by modification with hydrochloric acid. The physical-chemical characteristics of activated carbons were determined from nitrogen sorption isotherms, SEM-EDX, elemental analysis, FTIR, thermal analysis, and temperature programmed decomposition (TPD). According to the results obtained, chlorine is retained on the surface in an amount of 2%. The results of batch experiments indicate that maximum adsorption/ removal of nitrite ions can be achieved at pH = 3, being of 0.2 mg/g for CAN and 4.7 mg/g for CAN-Cl. To study the adsorption of nitrite ions on activated carbons the following mathematical models were used: pseudo-first-order, pseudo-second-order, and intraparticle diffusion kinetic models, and Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin-Pyzhev isotherm models.

This study aimed to investigate the feasibility and effectiveness of using a three-column continuous system for treating olive mill wastewater (OMW). The methodology involved passing the wastewater through three successive columns packed with various adsorbent materials. The efficiency was evaluated by measuring several chemical and physical properties before and after treatment, including pH, EC, TDS, acidity, turbidity, chloride, nitrate, nitrite, sulphate, phosphate, Na, K, Ca, Fe, Cu, total phenols, and total flavonoids. The initial values of these properties varied among the samples. After treatment, the measured properties were significantly changed, including an increase in pH from 4.8 to 6.9, EC from 12990 to 1407 µS/cm, turbidity from 7328 to 2791 NTU, chloride from 3400 to 422 ppm, nitrate from 307 to 4.34 ppm, Na from 293 to 178 ppm, K from 2243 to 86 ppm, Ca from 91 to 60 ppm, and a significant reduction in total phenols from 9821 to 35 mg/g. The results suggest that the proposed treatment is effective for purifying OMW and offers insights for developing sustainable and eco-friendly wastewater treatment methods.

A copper(II) chelate complex with diethylenetriamine (deta), [Cu(deta)2]Cl2·H2O (1), was synthesized by direct interaction of solid copper(II) chloride dihydrate with deta. Complex 1 was characterized by X-ray structural analysis, infrared (IR) spectroscopy and differential scanning calorimetry (DSC) and was studied as a flame retardant-hardener for epoxy resins. The crystals of 1 consist of [Cu(deta)2]2+ cations, Cl- anions and uncoordinated water molecules. Each Cu(II) atom is chelated with two tridentate molecules of deta, which bond to the central Cu(II) atom in a non-equivalent manner. This results in a distorted tetragonal bipyramidal environment around the Cu(II) atom. The crystal packing of the structural units in 1 is determined by both the dominant cation-anion interaction and strong hydrogen bonds, such as N-H···Cl, N-H···O, and O-H···Cl. Density functional theory (DFT) calculations were performed to determine the electron structure of 1 using the restricted formalism of B3LYP method with a 6-31G* orbital basis set. The d-orbitals of the Cu2+ ion are split due to the interaction of a tetragonal bipyramidal environment and the chelation, resulting in the visually observed dark blue color of crystals of 1. This color closely corresponds to the calculated value of the visible light wavelength (λ = 661.37 nm), which is related to the energy of photons absorbed by the complex (Δ = 1.874 eV).

Four new nickel(II), zinc(II) and manganese(III) complexes, [NiL] (1), [Zn3L2(OAc)2] (2), [ZnL(CH3OH)] (3) and [MnClL(DMF)] (4), derived from the bis-Schiff base N,N'-bis(4-bromosalicylidene)propane-1,2-diamine (H2L) have been prepared and characterized by spectroscopy methods, as well as single crystal X-ray determination. The Ni atom in the mononuclear nickel complex 1 is in square planar coordination. The outer and inner Zn atoms in the trinuclear zinc complex 2 are in square planar and octahedral coordination, respectively. The Zn atom in the mononuclear zinc complex 3 is in square pyramidal coordination. The Mn atom in the mononuclear manganese complex 4 is in octahedral coordination. Antibacterial activity of the complexes has been assayed on the bacteria Staphylococcus aureus and Escherichia coli, and the yeast Candida parapsilosis.

The early flexural and compressive strengths of fast setting SLU formulations based on a ternary system can be severely affected by the selection of accelerator, its quantity and chemistry. Besides design complexity, it is predicted that the current lithium resources will not be sufficient to meet the increasing demands from other markets and lithium prices are expected to increase. It is necessary to search for a new raw material that gives the same performance to prevent the possibility of a supply shortage in the construction sector. In this study, ternary system accelerated with aluminum sulphate was comprehensively investigated in comparison with commonly used accelerators. Aim to achieve is to provide early strength by using aluminum sulphate in the OPC-rich SLU formulation based on the ternary systems instead of traditional accelerators while obtaining cost saving solutions. For this purpose, fresh mortar properties and strength test were carried out according to EN 13813 and results were verified by monitoring hydration reactions over time by XRD and FTIR.

The focus of this systematic literature review was to examine eye-tracking studies in the chemistry classroom and to evaluate the usefulness of eye-tracking in studying students' learning of complex chemical concepts. The reviewed studies primarily used small samples of students, with undergraduate students being the most studied population, and measured variables such as eye movements, fixation time, pupil dilation, and others. The results show that higher performing students have shorter fixation time and learn better with models, with prior knowledge being an important factor. However, both students rely mainly on the symbolic level of presentations with better performing students being more successful at giving explanations. Problems with the complexity of data analysis were reported in the studies.

This study analyzed solvent extractions of Urelytrum giganteum Pilg, a perennial wild tufted grass in dry tropical African countries, to determine its antioxidant potential, chemical composition, proximate analysis, antimicrobial efficacy, and molecular docking. The ethanolic extract showed the highest antioxidant activity across various assays and showed the most substantial antibacterial activity against all tested bacterial strains. The phytochemicals identified included alkaloids, flavonoids, saponins, phenolic substances, tannins, carbohydrates, terpenes, and C-glycosides. The majority of the phytochemicals demonstrated notable inhibitory activity, with Stigmasterol showing the highest inhibition score.

Stahlianthus thorelii Gagnep. is used in traditional medicine to treat various diseases. In this study, ethyl acetate (EtOAc) extract of S. thorelii rhizomes was analyzed for its phychemicals, antioxidant activity and inhibition against enzymes (acetylcholinesterase, α-amylase, α-glucosidase, and tyrosinase). The EtOAc extract showed the presence of ferulic acid, catechin, epicatechin, epigallocatechin gallate, quercetin, and kaempferol, with average levels ranging from 169.29 to 2449.60 μg/g. Analysis of the volatile components of the extract revealed that β-patchoulene (23.1%), (E)-nerolidyl isobutyrate (11.9%), and aristolene (10.8%) were the major compounds. The antioxidant potential of the extract measured by DPPH (IC50 = 86.94 ± 2.87 μg/mL) and ABTS (IC50 = 743.60 ± 56.52 μg/mL) assays showed promising results. The inhibitory effects against acetylcholinesterase and α-amylase demonstrated potential with IC50 values of 246.43 ± 11.39 and 789.84 ± 8.27 µg/mL, respectively. The findings above suggest that the EtOAc extract of S. thorelii could contribute to supporting the treatment of certain diseases such as diabetes and Alzheimer's.

Neurocognitive decline during the perioperative period represents a risk of significant complications, including dementia and even death. Our prospective study included high-risk surgical patients who underwent large intestinal resections. Balanced anaesthesia was used to maximize cerebral protection. The release of NSE, protein S-100, matrix metalloproteinase-9 (MMP-9) and other biomarkers of cerebral injury and inflammation were measured during and after surgery to obtain the perioperative concentration profile and to identify possible clinically useful markers. Profiles of proteins MMP-9 and S-100 showed perioperative increase, which was in accordance with intraoperative cerebral injury. The S-100 and NSE plasma levels remained within normal values. The level of NSE even decreased, probably due to intraoperative fluid infusion. Our study showed that the use of neuroprotective anesthesia can reduce neuroinflammation. The study also highlights the perioperative expression of proteins MMP-9 and S-100, which might be useful as biomarkers of cerebral injury in the context of balanced anesthesia during major abdominal surgery.

To investigate the total secondary metabolite amounts, phenolic profile, antioxidant activity, acute toxicity, cytotoxic, and wound-healing effects of the aerial parts of Saponaria kotschyi (endemic) and Saponaria pumilio extracts. The total phenolic, flavonoid, saponin, and tannin contents; antioxidant activity (via six different methods, including β-carotene/linoleic acid, DPPH, ABTS, FRAP, phosphomolybdenum, and metal chelating assays); phenolic constituents in the extracts (HPLC method); acute toxicity (brine shrimp lethality test); antiproliferative effects on human cervical carcinoma (HeLa) and human neuroblastoma (SH-SY5Y) cancer cell lines (MTT assay); and the effects on wound healing in healthy mouse fibroblast cells (NIH-3T3) through an in vitro scratch assay were evaluated. The methanol extract of S. kotschyi demonstrated higher concentrations of secondary metabolites and antioxidant activity than S. pumilio. Both species predominantly contained caffeic acid, 2,5-dihydroxybenzoic acid, and epicatechin, though S. pumilio had a notably higher caffeic acid content. Additionally, S. kotschyi extract showed greater cytotoxicity against HeLa and SH-SY5Y cancer cells, while S. pumilio exhibited greater wound-healing efficacy. Two previously unexplored Saponaria species reveal a remarkable richness in secondary metabolites and potent antioxidant activity. Given their diverse phenolic constituents, these species emerge as promising candidates for therapeutic applications in cervical cancer and neuroblastoma, as well as playing a potentially critical role in tissue repair and regeneration-areas that merit further in-depth investigation.