Journal of Applied Science & Engineering Materials

SYNTHESIS OF E-CHALCONE DERIVATIVES BEARING DIFFERENT SUBSTITUENT GROUPS AND EVALUATION OF SUBSTITUENT EFFECTS ON THEIR SPECTROSCOPIC PROPERTIES

2026-10-01T11:55:31+00:00

Chalcones are simple yet significant structures containing various examples of enolate chemistry. Nowadays, these compounds can be synthesized in various ways, such as through methods like Claisen-Schmidt condensation. This method is commonly used due to its ease of application, high efficiency, and method diversity in synthesis. Due to their unsaturated structures, Chalcone derivatives can be used in different addition reactions. Also, they can be modified with various functional groups to achieve desired properties using simple starting reactants. These advantages make chalcone derivatives suitable for a wide range of applications. In addition to sensor applications, chemical probes, and fluorescence dyes, chalcone derivatives attract considerable attention in medical applications because of their diverse pharmacological activities such as anticancer, anti-HIV, and antibacterial activities.

In this study, various chalcone derivatives bearing suitable functional groups were synthesized, and their structures were characterized while their optical properties were systematically investigated. The structural analyses performed following the syntheses not only confirmed the structures of the synthesized compounds but also examined and substantiated the effects of the functional groups present on the corresponding molecular scaffold in terms of NMR and optical properties.

EXPERIMENTAL VIBRATION ANALYSIS OF A CANTILEVER BEAM UNDER MAGNETIC LEVITATION

2026-10-01T12:44:46+00:00

In this study, it is aimed to experimentally model a cantilever beam under the effect of electromagnetic force using a magnetic levitation (maglev) system and to investigate its vibration behavior. In the experimental setup, the free end of an aluminum beam fixed at one end is coated with a ferromagnetic material and exposed to the magnetic field generated by electromagnets. In this way, a contactless damping mechanism is achieved within the system. In the established experimental setup, the dynamic responses of the beam were measured under excitations applied at different frequencies, and frequency response functions were obtained. Using these data, the natural frequency and damping characteristics of the system were determined, and subsequently, experimental modeling was carried out using a second-order transfer function through optimization methods. Additionally, by varying the magnitude of the electromagnetic force, its effect on the damping ratio of the system was examined, and it was observed that increasing the magnetic force significantly reduces the vibration amplitude. Consistent with similar studies in the literature, it has been confirmed that the contactless electromagnetic damping method provides effective vibration suppression without altering the system dynamics compared to conventional mechanical dampers. The obtained results demonstrate that maglev-based electromagnetic systems offer high accuracy and applicability in the experimental modeling of flexible structures and active vibration control. This study provides an experimental contribution to the literature on the modeling of beam systems using a contactless damping approach.

DFT AND HF STUDY OF STRUCTURAL, SPECTROSCOPİC, THERMOCHEMİCAL, AND ELECTRONİC PROPERTİES OF 2-ETHOXY-5-FLUORO-1H-PYRİMİDİN-4-ONE

2026-10-01T12:52:14+00:00

A comprehensive quantum-chemical investigation of 2-ethoxy-5-fluoro-1H-pyrimidin-4-one (C6H7FN2O2) was carried out using density functional theory (DFT) and Hartree–Fock (HF) methods at the B3LYP/6-31+G(d,p) and HF/6-31+G(d) levels to elucidate its structural, spectroscopic, thermochemical, charge distribution, and electronic properties. The optimized geometry reveals a stable heterocyclic structure in which the pyrimidinone ring, fluorine substituent, carbonyl group, and ethoxy moiety collectively govern the molecular electronic structure. The calculated geometrical parameters indicate good agreement between the theoretical approaches, confirming the reliability of the optimized molecular model. Theoretical 1H and 13C NMR chemical shifts were evaluated using the GIAO method and compared with available experimental data recorded in CDCl3. The DFT calculations reproduce the experimental chemical shifts more accurately than the HF method, highlighting the importance of electron-correlation effects in predicting magnetic shielding constants. Significant deshielding is observed for carbon atoms bonded to electronegative nitrogen, oxygen, and fluorine atoms, whereas the ethoxy-group carbons and hydrogen atoms exhibit comparatively lower chemical shifts. Atomic charge distributions were also analyzed using both Mulliken population and atomic polar tensor (APT) schemes. The results reveal pronounced electronic polarization within the molecule, with the carbonyl oxygen, fluorine atom, and pyrimidine nitrogen n atoms carrying substantial negative charge densities, while several carbon and hydrogen atoms exhibit positive charge accumulation. The calculated charge distribution confirms the existence of efficient intramolecular charge redistribution regulated by the combined electron-withdrawing effects of fluorine and carbonyl functionalities. Additionally, thermochemical calculations indicate that the molecule possesses favorable energetic stability, while the calculated dipole moment displays its polar molecular nature. Frontier molecular orbital (FMO) analysis displays that the HOMO is mainly localized over the pyrimidinone ring and heteroatom-rich regions, whereas the LUMO is concentrated around the carbonyl- and fluorine-containing portions of the heterocyclic structure. This spatial separation facilitates intramolecular charge-transfer processes. The HOMO-LUMO energy gap together with the derived global reactivity descriptors, including electronegativity, chemical hardness, softness, chemical potential, and electrophilicity index, indicate a balanced combination of electronic stability and chemical reactivity. UV-Vis spectral analysis reveals that the electronic absorption behavior is dominated by π→π* and n→π* transitions involving the conjugated heterocyclic system and heteroatom lone-pair electrons. Furthermore, electrostatic potential (ESP) and m olecular electrostatic potential (MEP) analyses identify the carbonyl oxygen atom, fluorine atom, and ring nitrogen atoms as the most electron-rich regions, while the N-H and ethoxy hydrogen atoms constitute the principal positive potential zones. All in all, the theoretical results obtained show that 2-ethoxy-5-fluoro-1H-pyrimidin-4-one possesses a highly polarized electronic structure, well-defined reactive centers, and favorable charge-transfer characteristics. The findings provide a detailed understanding of its structural stability, spectroscopic behavior, and reactivity patterns, suggesting potential relevance in pharmaceutical, agrochemical, and functional-material applications.

NETWORK INTRUSION DETECTION USING MACHINE LEARNING ALGORITHMS ON THE NSL-KDD DATASET: A COMPARATIVE EXPERIMENTAL STUDY

2026-10-01T13:01:53+00:00

The automatic detection of malicious activity in network traffic is one of the most critical components of today’s cybersecurity infrastructure. This study presents a reproducible experimental comparison that evaluates the binary classification performance—specifically, the ability to distinguish between normal and attack traffic—of three different machine learning classifiers (Logistic Regression, Decision Tree, and Random Forest) on the NSL-KDD dataset, which is widely used in the attack detection systems literature. To this end, a common Python evaluation pipeline was established, consisting of steps such as converting categorical features (e.g., protocol type, service, flags) to numerical form, standardizing the features, performing stratified training/test splits, and evaluating the models using metrics such as accuracy, precision, sensitivity, F1-score, and ROC-AUC metrics. The experimental results showed that the Random Forest model achieved the highest performance with 99.90% accuracy, a 99.89% F1-score, and an AUC of 1.00; this superiority was found to be statistically significant at p <0.001 and was confirmed to be robust via 5-fold cross-validation. The results obtained quantitatively demonstrate the extent to which tree-based ensemble methods offer an advantage over linear models in NSL-KDD and show that the common evaluation protocol used can be easily extended to different datasets and classifiers.

FRAGRANCE MICROENCAPSULATION BY OIL-IN-WATER IN SITU POLYMERIZATION: CARTIONIC SURFACE FUNCTIONALIZATION FOR LONG-TERM DISPERSION STABILITY

2026-10-01T13:05:27+00:00

Today, many commercially available fabric softeners contain encapsulated fragrances to provide consumers with prolonged release of the fragrance even after extended storage periods. Among various techniques, in situ polymerization is one of the most common methods, as it offers a cost-effective and easily scalable method for fragrance encapsulation. In that regard, the primary performance requirements are generally fragrance protection and prolonged release. On the other hand, the dispersion stability of the microcapsules prior to addition to a fabric softener formulation is as important as the primary requirements since in many commercial applications, capsule systems are supplied as ready-to-use capsule dispersions. In this context, this study investigates the preparation of fragrance-loaded microcapsules using methanol-modified melamine-formaldehyde resin (MMF) and their post-curing modification with glycidyl trimethylammonium chloride to improve long-term dispersion stability. Optical microscopy and SEM analyses revealed predominantly spherical microcapsules with sizes in the 20-30 μm range, and TGA was conducted to support the presence of the thermally resistant MMF shell. It was found that modification with glycidyl trimethylammonium chloride did not alter the performance but provided long-term dispersion stability and suggested improved deposition and retention on the fabric after laundering.