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Comparative analysis of chemically and thermally modified potato starch for the adsorption of brilliant green dye
No full textThis study presents a comparative analysis of adsorbents obtained by chemical and
thermal modification of potato starch, applied to improve its structural properties and adsorption
performance. Chemical modification was performed using the amino acid cysteine, while thermal
treatment was conducted through the hydrothermal carbonization and subsequent chemical
activation. The resulting starch-based materials were characterized using Fourier Transform
Infrared Spectroscopy to identify the changes in surface functional group content and Scanning
Electron Microscopy to examine morphological alterations. The adsorption capabilities of the
modified starches were evaluated using brilliant green dye as a model organic pollutant. Results
indicated that both modification methods significantly altered the starch structure, but in different
ways, leading to varied effects on dye adsorption efficiency. The chemically modified starch showed
enhanced functionalization, while thermal treatment converted starch to carbonized material and
completely changed its surface morphology. This comparative approach highlights the potential of
both methods in tailoring starch-based adsorbents for application in wastewater treatment. Overall,
the modified materials demonstrated improved adsorption capacity for brilliant green compared to
native starch, confirming their suitability as biodegradable and cost-effective adsorbents for organic
dye removal from aqueous solutions
Corrosion resistance of welded joint zones made of AISI 316L stainless steel
No full textThe objective of this research is to examine the corrosion behavior of welded joints made from AISI 316L austenitic stainless steel, with a particular focus on general, galvanic, pitting, and intergranular corrosion. A comprehensive experimental approach was applied, including chemical and mechanical characterization, microscopic analysis, and electrochemical testing. The results revealed that variations in microstructure, especially in the heat-affected zone (HAZ), lead to reduced resistance to localized corrosion forms. Electrochemical impedance spectroscopy (EIS) and Tafel analysis confirmed that the corrosion resistance of welded regions was lower compared to the base material. The weld metal (WM) exhibited a slightly more negative corrosion potential, indicating a higher susceptibility to galvanic corrosion. Pitting corrosion resistance was notably diminished in the HAZ, likely due to partial sensitization induced by excessive heat input Intergranular corrosion tests, including oxalic acid etching and Double Loop Electrochemical Potentiokinetic Reactivation test (DL-EPR) confirmed acceptable behavior of the base material and HAZ, while the weld metal showed increased vulnerability. Furthermore, the potential increased content of CO₂ in the shielding gas might led to surface defects and microstructural changes, contributing to the overall decline in corrosion resistance. These findings highlight the critical influence of welding parameters on corrosion behavior and emphasize the need for precise process control to ensure long-term performance and structural reliability in corrosive environments
Crystal structure of a new 2,2'-dipyridylamine polymorph
No full text2,2'-Dipyridylamine (dipya) is an organic charge transfer base that can exist in a variety of protonation states, allowing it to adopt one of nine coordination modes [1]. This molecule has attracted attention as a ligand in coordination chemistry due to the inherent flexibility of the amine N atom and its ability to stabilize transition metal complexes [2, 3]. The chemistry of dipya is characterized by the diverse geometries around the amine N atom, as well as the enhanced acidity of the amine H atom occurring as a result of complex formation [1]. Dipya possesses two rotational degrees of freedom around the N–C bonds, thus serving as a model with which to study structural differences and phase transitions. To date, three distinct polymorphs of dipya have been identified: namely, triclinic (P1), monoclinic (P21/c) and orthorombic (Pccn), with melting points of 366, 364 and 360 K, respectively [4–6]. Recently, a fourth modification of dipya was discovered. Colourless single crystals of a new monoclinic polymorph were prepared by slow evaporation method at room temperature. Single crystal X-ray analysis revealed that the asymmetric unit consists of two dipya moieties linked by strong N–H···N hydrogen bonds into a dimer (Figure 1a). The main structural feature is a supramolecular tape formed by N/C–H···N interactions along c axis, while weak C–H···N and C–H···π interactions were observed between the tapes resulting in the formation of supramolecular 3D network (Figure 1b). Crystallographic data: C10H9N3, Mr = 171.2, monoclinic, P21/n, a = 11.714(2), b = 12.424(3), c = 12.200(2) Å, β = 94.21(3) °, V = 1770.9(6) Å3, Z = 8, R1 = 0.0422, wR2 = 0.1096, S = 1.026 for 236 parameters and 3228 reflections. Figure 1. a) ORTEP diagram of a new polymorph showing 30% displacement ellipsoids. H atoms are presented as small spheres of arbitrary radii. The intramolecular N–H···N hydrogen bonds are shown as dotted lines; b) Supramolecular 3D networking of dipya via N/C–H···N and C–H···π interactions (green Cg1: C1–C5/N1, orange Cg2: C16–C20/N6)
Determining the Potential of Placental Tissue Derivatives for Use in Post-Mastectomy Breast Reconstruction: Development of a 3D-Printed Bioscaffold- AmnioPrintCare project
No full textBreast reconstruction after mastectomy is considered safe and
easible for patients with breast cancer, however, current techniques are
ssociated with potential complications and do not significantly influence
disease recurrence risk compared to mastectomy alone. This highlights the
meed for improved strategies in breast reconstruction. ..
Twisted amides based on the spirohydantoin scaffold as potential anticancer agents
No full textA series of cyclohexanespiro5-hydantoins bearing either a 4-substituted benzoyl group (compounds 1–6) or a 2-(4-substituted phenyl)-2-oxoethyl group (compounds 7, 8) in position 3 was synthesized and structurally characterized. Compounds 1–6 feature a distorted exocyclic amide bond that results from the twisting in a combination with pyramidalization of the N3 atom. Particularly, compound with a fluoro substituent (3) contains one of the most distorted acyclic amide bonds reported so far. The cytotoxic effects of the investigated compounds were evaluated against human cancer cell lines: cervical adenocarcinoma (HeLa), colorectal adenocarcinoma (LS174T), lung epithelial carcinoma (A549) as well as normal human lung fibroblasts (MRC5) cell line. It appeared that moderately distorted twisted amides with highly lipophilic substituents showed high cytotoxic potency against selected cancer cell lines. Compound 6 bearing a tert‑butyl group demonstrated the highest cytotoxic activity against all cell lines tested, with IC50 values ranging from 10.08±3.90 to 15.86±4.64 µM against HeLa and LS174T cell line, respectively. Compound 5 with a bromo substituent was the next one in terms of cytotoxic activity against HeLa cell line with IC50 value of 36.03±10.15 µM and against LS174T cell line with IC50 value of 48.03±3.92 µM. This compound showed the highest selectivity toward HeLa cell line compared to normal MRC cell line with the selectivity coefficient of 2.42. The cell cycle analysis demonstrated that compounds 5 and 6 exerted a potent proapoptotic effect on HeLa cancer cells in vitro. Furthermore, we analyzed the molecular binding features of the investigated compounds with the vascular endothelial growth factor receptor 2 (VEGFR-2) that is responsible for stimulation of pathological angiogenesis. The study of structural and biological properties of the investigated compounds provided guidelines for the development of twisted amides with potential cytotoxic activity
Influence of Zirconia Surface Characterization on Its Wettability and Cell Proliferation
No full textIntroduction: Zirconium dioxide (ZrO2) ceramic has become an increasingly important biomaterial in dental applications due to its high mechanical strength, biocompatibility, and abrasion resistance. However, there is a lack of knowledge on how different surface topographies of ZrO2 ceramics influence the biological response of adhered cells. Therefore, this study aimed to compare the physical properties and proliferation of fibroblasts that adhered to the surfaces of polished and glazed ZrO2 ceramics. ..
Monitoring of pesticide residues in apples: A case study from the Belgrade market
No full textApples are among the most popular fruits in the world due to their health benefits. However, because of
multiple pesticide applications during the growing season, they may contain residues that can affect
food quality and human health. The European Commission (EC) is constantly reviewing the safety of
pesticide use, with many active substances being withdrawn from European orchard protection
programmes or having their maximum residue levels (MRLs) in fruits reduced due to their pronounced
toxicity [1]. This study aimed to investigate the occurrence of frequently used pesticides (fungicides,
insecticides and herbicides) in apples collected from different retail outlets in Belgrade, in order to inform
consumers about their presence and possible health risks. Pesticide extraction was performed using the
QuEChERS method, followed by detection using liquid chromatography–tandem mass spectrometry
(LC–MS/MS) [2]. The results showed widespread pesticides contamination in apples on the Belgrade
market, with residue concentrations ranging from a few μg kg–1 to several hundred μg kg–1, based on
fresh weight of samples. Fungicides fludioxonil and pyraclostrobin, and insecticides acetamiprid and
chlorantraniliprole, were the most frequently found in apple samples, with pyraclostrobin found at a
concentration of 686 μg kg–1 exceeding its MRL of 0,5 mg kg–1. The observed levels of pesticide
residues indicate a potential health risk for consumers, and the contribution of total dietary intake of
pesticides, as well as their possible synergistic effects, cannot be ignored. These results highlight the
need for long-term monitoring of pesticide residues in apples and stricter implementation of regulations
in the field of food production and safety in the Republic of Serbia
Biotransformation of xylan isolated from sunflower meal into xylo-oligosaccharides using endo-xylanase immobilized on oxidized nanocellulose
No full textIn recent years, oxidized nanocellulose (Ox-CNC), obtained via periodate oxidation, has been widely used in foods, cosmetics, and biomedical fields due to its unique characteristics such as biodegradability, antimicrobial activity, non-toxicity, crystalline structure, and presence of reactive dialdehyde groups on its surface. Herein, a novel sustainable, cost-effective, and clean approach using xylanases enzyme preparation ROHALASE® SEP-VISCO immobilized on Ox-CNC was applied and utilized for the transformation of xylan, isolated from agro-food waste, into xylo-oligosaccharides (XOS), considered as emerging prebiotics. The study has confirmed the efficient covalent immobilization of xylanase onto the obtained dialdehyde-modified cellulose nanocrystals (Ox-CNC) with the yield of xylanase immobilization of 55 %. The highest specific activity of the immobilized xylanase (1.5 IU/mg proteins) was achieved in optimal conditions: initial enzyme concentration of 400 mg/g of support, pH of 9.5, and a reaction time of 3 h. This study proved concept of the application of cellulose nanomaterials in green processes for the production of potential prebiotics from agro-food waste since immobilized enzyme was applied in reaction with xylan obtained by fractionation of sunflower meal (SFM). Ox-CNC-xylanase demonstrated an XOS productivity yield of 31 % based on the total SFM xylan content after 3 h. Additionally, the prebiotic activity was confirmed in a microbiological test within which the resulting mixture rich in XOS selectively stimulated the growth of some commensal gut microbes (Lactiplantbacillus plantarum 299v, Lacticaseibacillus rhamnosus GG and Saccharomyces boulardii CBS 5926) in comparison with pathogenic species (Escherichia coli ATT 25,922)
Tehnološki postupak za proizvodnju ekstrakata zelenog čaja sa visokim sadržajem biološki vrednih jedinjenja
No full textSa porastom interesovanja za ekstrakte zelenog čaja raste i potreba za primenom efikasnog i održivog procesa koji će omogućiti velike prinose uz upotrebu ekološki prihvatljivih procesnih medijuma. Problemi povezani sa konvencionalnim tehnikama ekstrakcije (velika potrošnja energije, upotreba toksičnih organskih rastvarača, dugo vreme ekstrakcije i ograničena selektivnost) čine ih manje poželjnim u ekstrakciji prirodnih bioaktivnih komponenti iz biljnog materijala namenjenih za ljudsku upotrebu. Zbog navedenog, predloženo tehničko rešenje opisuje tehnološki postupak dobijanja ekstrakta zelenog čaja sa visokim sadržajem bioaktivnih komponenti i jakom antioksidativnom aktivnošću korišćenjem ekološki prihvatljivog procesa ekstrakcije koji se zasniva na upotrebi zelenog rastvarača. Sadržaj fenolnih i flavonoidnih komponenti uključujući i sadržaj katehina u dobijenim ekstraktima kao i njihova sposobnost da inhibiraju DPPH radikal su detaljno ispitana. Varijacijom u izboru tehnike ekstrakcije, temperature i sastava procesnog medijuma (rastvarača) postignuto je selektivno izolovanje odgovarajućih grupa sekundarnih metabolita iz zelenog čaja. Proizvod dobijen u relativno velikoj količini (većoj od 39 mass%) u optimizovanom procesu ekstrakcije ima bolja svojstva od komercijalno dostupnih proizvoda i onih dobijenih konvencionalnim tehnikama ekstrakcije, a proizveden je za relativno kratko vreme (90 minuta) upotrebom zelenog rastvarača (50% vodenog rastvora etanola) koji se može reciklirati. Predmetno tehničko rešenje nudi zamenu tehnologija koje se smatraju štetnim po zdravlje i životnu sredinu zelenim pristupom za proizvodnju ekstrakta zelenog čaja za primenu u proizvodnji funkcionalne hrane, kozmetike i farmaceutskih suplemenata. Predloženi savremeni tehnološki proces ekstrakcije ima za cilj dobijanje čistih krajnjih proizvoda (koji ne sadrže toksične organske rastvarače) sa velikim sadržajem bioaktivnih komponenti i jakom antioksidativnom aktivnošću koji ne zahtevaju dalje prečišćavanje.Tehničko rešenje kategorije M83 – Bitno poboljšano tehničko rešenje na međunarodnom nivo
Activity and Operational Loss of IrO2-Ta2O5/Ti Anodes During Oxygen Evolution in Acidic Solutions
No full textThe oxygen-evolving IrO2-Ta2O5/Ti anode (OEA), primarily used in electrolyzers for plating, metal powder production, electrowinning (EW), and water electrolysis, is analyzed. This study focuses on the distribution of oxygen evolution reaction (OER) activity and the associated operational loss over the randomized OEA texture. The OER activity and its distribution across the IrO2-Ta2O5 coating surface are key factors that influence EW operational challenges and the lifecycle of OEA in EW processes. To understand the OER activity distribution over the coating’s randomized texture, we performed analyses using anode polarization in acid solution at both low and high (EW operation relevant) overpotentials and electrochemical impedance spectroscopy (EIS) during the OER. These measurements were conducted on anodes in both their as-prepared and deactivated states. The as-prepared anode was deactivated using an accelerated stability test in an acid solution, the EW simulating electrolyte. The obtained data are correlated with fundamental electrochemical properties of OEA, such as structure-related pseudocapacitive responses at open circuit potential in the same operating environment. OER and Ir dissolution kinetics, along with the physicochemical anode state upon deactivation, are clearly characterized based on current and potential dependent charge transfer resistances and associated double layer capacitances obtained by EIS. This approach presents a useful tool for elucidating, and consequently tailoring and predicting, anode OER activity and electrolytic operational stability in industrial electrochemical applications