Chemija

Titulinis

Pr, 22 Grd 2025 00:00:00 +0200

Turinys

Pr, 22 Grd 2025 00:00:00 +0200

Thespesia populnea sėklų acetono ekstrakto terapinis profiliavimas: su mangrovėmis susijęs antioksidacinio, antimikrobinio ir citotoksinio aktyvumo šaltinis

Pr, 22 Grd 2025 00:00:00 +0200

The seeds of Thespesia populnea, a mangrove-associated plant, remain understudied despite their potential bioactivity. Among various extracts, the acetone extract showed the highest polyphenol (186.13 ± 0.06 mg GAE/g) and flavonoid (475.71 ± 8.08 mg QE/g) contents. Antioxidant assays demonstrated a significant free radical scavenging activity. It exhibited strong antimicrobial effects, with inhibition zones of 16–18 mm against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and MIC values of 28 µg/mL (Candida albicans) and 51 µg/mL (Aspergillus niger). The MTT assay revealed selective cytotoxicity against MCF-7 breast cancer cells (IC50 = 76.8 ± 2.1 µg/mL) over L929 normal fibroblasts (IC50 = 286.34 ± 1.8 µg/mL). GC–MS and FTIR analyses confirmed the presence of bioactive phytochemicals responsible for these effects. This is the first comprehensive report highlighting the antioxidant, antimicrobial and anticancer potential of T. populnea seed extract, supporting its relevance as a promising natural candidate for biomedical applications.

Vienalaikis adsorbcinis bismuto(III) ir indžio(III) voltamperometrinis nustatymas naudojant varferoną kaip kompleksus sudarantį reagentą – taikymas aplinkos vandenyse

Malgorzata Grabarczyk, Marzen Fialek — Pr, 22 Grd 2025 00:00:00 +0200

A renewable mercury film silver-based electrode (Hg(Ag)FE) in combination with adsorptive stripping voltammetry is evinced as a simple and fast approach for a simultaneous quantification of indium(III) and bismuth(III) in natural water samples. In order to effectively preconcentrate and obtain signals from both analytes in one measurement, cupferron was used as a complexing agent. Optimal conditions were found to be as follows: 0.1 mol L–1 acetate buffer (pH = 4.6), 3 × 10–4 mol L–1 cupferron, accumulation potential of –0.1 V and accumulation time of 60 s. A linear response of In(III) and Bi(III) in a concentration range of 2 × 10–9 to 1 × 10–7 mol L–1 (r = 0.9986) was gained with a detection limit of 6.5 × 10–10 mol L–1 for In(III) and 8.3 × 10–10 mol L–1 for Bi(III), respectively. Analytical results of the analysis of river water samples demonstrated that the elaborated voltammetric method is apposite for direct environmental water analysis.

Aukštos kokybės uogų degtinė „Berrovka“: gamyba ir tyrimas dujų chromatografijos ir masių spektrometrijos metodu

Pr, 22 Grd 2025 00:00:00 +0200

Braškių, aviečių, vyšnių, serbentų ir agrastų uogos, užaugintos paprastomis namų sąlygomis ir perdirbtos į uogienes, buvo naudojamos aukštos kokybės uogų degtinei „Berrovka“ gaminti. Šiame tyrime distiliatai, gauti iš fermentuotų mišrių uogienių atliekų, buvo analizuojami dujų chromatografijos ir masių spektrometrijos (GC–MS) metodu optimizuotomis sąlygomis, siekiant įvertinti tiek kokybinę, tiek kiekybinę distiliavimo produktų sudėtį. Kokybinė distiliavimo frakcijų analizė atskleidė ryškius lakiųjų junginių sudėties skirtumus įvairiuose distiliavimo proceso etapuose. Distiliavimo frakcijos, surinktos nuo 10.30 val. iki 19.15 val., buvo išsamiai ištirtos. Nustatyta, kad pagrindinių lakiųjų junginių, tokių kaip acetaldehidas, metanolis, 1-propanolis, izobutanolis, izoamilacetatas, izoamilo alkoholis, etilo heksanoatas, 2-hidroksipropiletanoatas, acto rūgštis, furfurolas, 1,2-butandiolis ir benzilo alkoholis, smailių plotai žymiai mažėjo distiliacijos proceso metu. Galutinė distiliavimo frakcija buvo gryniausia, joje buvo mažiausia lakiųjų junginių koncentracija. Sukurtas kiekybinės analizės metodas, naudojant GC-MS su pasirinktu jonų stebėjimo režimu, leidžiančiu tiksliai nustatyti pagrindinių lakiųjų priemaišų koncentracijas. Tyrimo rezultatai patvirtino, kad pagrindinė naminės uogų degtinės frakcija atitinka saugos ir kokybės standartus ir gali būti naudojama maisto ir degalų pramonėje be apribojimų.

Integralus elektrokatalizinio aktyvumo vertinimo rodiklis

Vyacheslav S. Protsenko, Dmytro O. Makhota — Pr, 22 Grd 2025 00:00:00 +0200

This study introduces an integral metric of electrocatalytic activity, which is based on the comparison of the area under the polarisation curve in current density vs overpotential coordinates over a specific chosen overpotential range. This metric is applied to evaluate and compare several electrocatalysts, allowing for a more comprehensive understanding of electrocatalytic performance. Unlike traditional metrics, which characterise electrocatalyst behaviour under specific conditions (e.g. a particular overpotential or current density), the proposed integral metric provides a broader evaluation over a wide operational range. This approach is particularly useful for electrocatalysts with different Tafel slopes and polarisation characteristics. The metric is shown to be invariant to the shape of the polarisation curve and can be applied even when the exact form of the analytical dependence is unknown. The application of this metric holds promise for both fundamental studies in electrocatalysis and for practical applications in

Efektyvus PAH ir PCB skaidymas sąvartyno filtrate fotofentonu, naudojant iš perdirbto PET susintetintą Fe-CoBDC@Fe3O4 katalizatorių

Pr, 22 Grd 2025 00:00:00 +0200

Landfill leachate is highly challenging to treat due to its complex and unstable composition, containing high concentrations of ammonia nitrogen, chemical oxygen demand (COD), heavy metals, and persistent organic pollutants such as polyaromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). In this study, a novel heterogeneous photo-Fenton catalyst, Fe-CoBDC@Fe3O4, was synthesised via a thermosolvent method using terephthalic acid regenerated from PET waste. The catalyst was employed for the degradation of recalcitrant compounds in leachate following pretreatment with an activated solid reactor. Upon UV irradiation (240 nm), the Fe-CoBDC@Fe3O4 catalyst generates electron–hole pairs, where the holes (h+) oxidise water or hydroxyl ions (OH-) to form hydroxyl radicals (•OH), which in turn degrade organic pollutants. Optimal treatment conditions were identified as a catalyst dosage of 1 g/L, H2O2 dosage of 0.8 mL, pH 3.0, and a reaction time of 30 min. Under these conditions, the removal efficiency of 97% for COD, 85% for PAHs and 84% for PCBs was achieved. These results demonstrate that Fe-CoBDC@Fe3O4 is a highly effective and sustainable photo-Fenton catalyst for the treatment of refractory compounds in industrial leachate.

Organinio silicio modifikuotų kardanolio-fenolio dervų paruošimas ir eksploatacinių savybių apibūdinimas

Shusheng Gong, Guomei Xu, Chen Han, Chunfen Huang, Hanjie Ying, Hongxue Xie — Pr, 22 Grd 2025 00:00:00 +0200

This study presents the synthesis and characterisation of KH550-modified cardanol-based phenolic hybrid resins. The hybrid resins were prepared via a two-step process: (1) synthesis of cardanol-based phenolic resin (CPR) through the condensation of cardanol and paraformaldehyde (1:1.3 molar ratio of phenolic hydroxyl groups to aldehyde groups), followed by (2) ultrasound-assisted grafting of γ-aminopropyltriethoxy silane (KH550) at varying mass ratios (5 and 15 wt%, denoted as CPR-K5 and CPR-K15, respectively). Hydrolysis of KH550 generated silanol (Si–OH) groups, which underwent covalent grafting and condensation reactions with the phenolic hydroxyl groups (–OH) and hydroxymethyl groups (–CH2OH) of CPR to form Si–O–C crosslinked networks, as confirmed by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Scanning electron microscopy (SEM) revealed the homogeneous dispersion of the organosilicon phase within the resin matrix. Thermogravimetric analysis (TGA) demonstrated a significant enhancement in thermal stability, with the char yield at 800°C increasing from 7.8% (neat CPR) to 22.1% (CPR-K15). Stress-strain tests verified the enhanced mechanical performance, with the Young’s modulus of CPR-K5 reaching 104.7 MPa (representing a ~512% increase compared to neat CPR, 17.1 MPa) and that of CPR-K15 being 52.2 MPa (~205% increase vs neat CPR). This work provides a facile strategy for preparing sustainable hybrid resins with tailored thermomechanical properties, addressing the inherent brittleness and a low char yield of conventional cardanol-based phenolic resins. The resulting materials show potential for high-temperature structural applications and flame-retardant composites.

Rolandas Kazlauskas (1941 01 02–2025 07 08)

Pr, 22 Grd 2025 00:00:00 +0200

Liudvikas Kimtys (1940 08 17–2025 09 15)

Pr, 22 Grd 2025 00:00:00 +0200