Search Results (182)

Molecularly imprinted polymers (MIPs) for silver sorption were synthesized using diethylene glycol dimethacrylate (DEGDMA) and divinylbenzene (DVB) as crosslinking agents. Synthesis was carried out using a ratio template: monomer: monomer: cross-linker = 1:2:2:8. The yield of obtained imprinting structures was 63.2% and 67.8% for MIP(DEGDMA) and MIP(DVB), respectively. The MIPs were analyzed by FTIR analysis, which showed the presence of characteristic peaks indicating the presence of monomers and crosslinkers in the MIP structure. According to the results of SEM analysis, the average cavity size for MIP(DEGDMA) is 0.81 ± 0.20 μm and for MIP(DVB) is 0.68 ± 0.23 μm in diameter. MIP(DEGDMA)’s sorption degree is 66.08%, and its sorption capacity is 3.31 g/g; MIP(DVB)’s sorption degree is 78.35%, and its sorption capacity is 3.92 g/g. The desorption degree is 69.85% for MIP(DEGDMA) and 69.52% for MIP(DVB). For analysis of sorption kinetics, the Radushkevich and Elovich kinetic models were applied. Full article

The white oil-bearing rose (R. alba L.) is the second of the industrially important rose species for Bulgarian rose cultivation and essential oil production. In recent years, the interest in white oil-bearing rose has increased, following the worldwide trend for searching for new aromatic alternatives. Therefore, the purpose of the current research is to evaluate the volatile compounds profile of fresh R. alba L. flowers using headspace solid-phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC/MS). More than 75 individual compounds were identified and quantified using HS-SPME-GC/MS. The study revealed that the aroma-bearing fraction of rose volatiles consists mainly of monoterpene alcohols; 2-phenylethanol was the most abundant component (8.4–33.9%), followed by geraniol (12.8–32.5%) and citronellol + nerol (17.7–26.5%). Linalool, α-pinene, β-myrcene, and rose oxides were also observed in low concentrations. The stearopten fraction in the HS phase was observed in low concentration, with main representatives nonadecane + nonadecene, heptadecane, heneicosane, and tricosane. The HS-GC profile of the R. alba fresh flowers shows distinct differences in relative abundance of the components between the two studied clones of the population, as well as between volatiles in petals and in the whole blossom. The absence of some undesirable components, such as allergenic and potentially carcinogenic methyl eugenol in fresh R. alba blossom, makes white oil-bearing rose a promising alternative to R. damascena in perfumery, natural cosmetics, and aromatherapy. Full article

A simple and innovative synthesis strategy was established to produce polymer microspheres with a distinctive walnut-like morphology, incorporating Fe₃O₄ nanoparticles within their structure. This was achieved through γ-ray-initiated mini-emulsion polymerization. To ensure high encapsulation efficiency, the surface of the Fe₃O₄ nanoparticles was chemically altered to shift their wettability from hydrophilic to hydrophobic, enabling uniform dispersion within the monomer phase before polymerization. The formation of the walnut-like architecture was found to be significantly influenced by both the polymerization dynamics and phase separation, as well as the shrinkage of the crosslinked polymer network formed between the monomer and the resulting polymer. Divinylbenzene (DVB) was chosen as the monomer due to its ability to generate a mechanically stable polymer framework. The γ-ray irradiation effectively initiated polymerization while preserving structural coherence. A detailed analysis using FTIR, SEM, and TEM confirmed the successful fabrication of the Fe₃O₄-loaded polymer microspheres with their characteristic textured surface. Moreover, magnetic characterization via vibrating sample magnetometry (VSM) indicated pronounced superparamagnetic behavior and strong magnetic responsiveness, highlighting the potential of these microspheres for advanced biomedical applications. Full article

Turbo Codes (TCs) are a family of convolutional codes that provide powerful Forward Error Correction (FEC) and operate near the Shannon limit for channel capacity. In the context of modern communication systems, such as those conforming to the DVB-RCS2 standard, Turbo Encoders (TEs) play a crucial role in ensuring robust data transmission over noisy satellite links. A key computational bottleneck in the Turbo Encoder is the non-uniform interleaving stage, where input bits are rearranged according to a dynamically generated permutation pattern. This stage often requires the intermediate storage of data, resulting in increased latency and reduced throughput, especially in embedded or real-time systems. This paper introduces a vector processing algorithm designed to accelerate the interleaving stage of the Turbo Encoder. The proposed algorithm is tailored for vector DSP architectures (e.g., CEVA-XC4500), and leverages the hardware’s SIMD capabilities to perform the permutation operation in a structured, phase-wise manner. Our method adopts a modular Load–Execute–Store design, facilitating efficient memory alignment, deterministic latency, and hardware portability. We present a detailed breakdown of the algorithm’s implementation, compare it with a conventional scalar (serial) model, and analyze its compatibility with the DVB-RCS2 specification. Experimental results demonstrate significant performance improvements, achieving a speed-up factor of up to 3.4× in total cycles, 4.8× in write operations, and 7.3× in read operations, relative to the baseline scalar implementation. The findings highlight the effectiveness of vectorized permutation in FEC pipelines and its relevance for high-throughput, low-power communication systems. Full article

The glass transition temperature (T_g) is undoubtedly one of the most important characteristics of polymers, and investigating its dependence on their structure and composition is crucial from both fundamental and application points of view. This study deals with the unexpected relationship between T_g and the average molecular weight between crosslinking points (M_c) in nanophase-separated polystyrene-l-poly(dimethylsiloxane) (PSt-l-PDMS) and polystyrene-l-poly(dimethylsiloxane)/divinylbenzene (PSt-l-PDMS/DVB) polymer conetworks. In order to reveal the correlation between the T_g and M_c, a library of PSt-l-PDMS and PSt-l-PDMS/DVB conetworks was synthesized, and their compositions and T_gs were determined. Instead of the expected increase of T_g with decreasing M_c, a reverse correlation was found. Namely, the T_g decreases with decreasing M_c in these conetworks. Correlation analyses showed that the T_g linearly depends on 1/M_c, similar to the Fox–Flory relationship for homopolymers with their M_n, that is, T_g = T_g,ꝏ −K/M_c for the investigated conetworks, independent of the absence or presence of relatively low amounts of DVB as an additional small molecular weight crosslinker. This means that the PDMS macrocrosslinker acts like scissors by interrupting the mobility of the crosslinked PSt chains in the conetworks, and the T_g of the PSt segments will be close to that of PSt homopolymers with the same M_n as M_c, as found by comparison. Consistent with previous findings with other conetworks, the presence of the scissors effect of the macromolecular crosslinker in the PSt-l-PDMS and PSt-l-PDMS/DVB conetworks indicates that the scissors effect is a general phenomenon for polymer conetworks formed by crosslinking with a macromolecular crosslinker. The observed unusual T_g versus M_c relationship in the conetworks can be utilized in designing such novel materials with predetermined T_gs required for targeted applications. Full article

In previous studies, a new methodology was developed to determine the free dispersive and polar energies, the surface energies, and Lewis acid–base parameters of a polystyrene–divinylbenzene (S-DVB) copolymer modified by melamine, 5-Hydroxy-6-methyluracil, and 5-fluouracil. In this paper, we were interested in the determination of the work of the adhesion of solvents on the modified copolymer as a function of temperature and for the different modifiers with the help of inverse gas chromatography at infinite dilution. The variations in the London dispersive and polar surface properties of copolymers against the temperature led to the determination of the different acid–base components of their surface energies. Using Fowkes’s equation, van Oss’s relation, and Owens’s concept, we obtained the variations in the dispersive and polar works of the adhesion of the different solid surfaces, and the corresponding forces of interaction between the organic solvents and the modified copolymer. It was shown that the work of adhesion is a function of two thermodynamic variables: the temperature and the modifier percentage. Full article

A solid phase microextraction (SPME) method coupled with liquid chromatography (LC) and fluorescence/ultraviolet-diode array detection was developed for the simultaneous determination of quercetin and trans-resveratrol. The chromatographic, detection, and SPME extraction/desorption conditions were systematically optimized. The performance of four commercial SPME fibers—polyacrylate (PA), polyethylene glycol (PEG), polydimethylsiloxane (PDMS), and polydimethylsiloxane-divinylbenzene (PDMS-DVB)—was evaluated and compared with a homemade polydopamine (PDA)-coated fiber. While all of the fibers successfully extracted the target analytes, their efficiencies varied significantly. The PA, PEG, and PDA fibers demonstrated superior performance, exhibiting wide linearity ranges (0.03–1 µg/mL (PA and PEG) and 0.06–1 µg/mL (PDA) for quercetin, 0.01–1 µg/mL for trans-resveratrol); high sensitivity (LODs of 0.01 µg/mL (PA and PEG) and 0.02 µg/mL (PDA) for quercetin, 0.003 µg/mL for trans-resveratrol); and excellent precision. Among these, the polyacrylate coating delivered the best analytical performance and was selected for further application. The optimized method was applied to analyze winemaking by-products (seeds, skins, and stalks) using SPME on ethanol-macerated extracts subjected to brief ultrasonication. Quercetin and trans-resveratrol were quantified in pomace extracts at concentrations of 104.3 ± 8.2 µg/g and 38.5 ± 4.1 µg/g, respectively. Recovery experiments confirmed the method’s accuracy, with recoveries of 99.1 ± 7.4% for quercetin and 98.5 ± 9.8% for trans-resveratrol. This study establishes a reliable, sensitive, and efficient approach for the determination of these bioactive compounds in complex matrices, with potential applications in the food and pharmaceutical industries. Full article

Polymer conetworks, which consist of two or more covalently crosslinked polymer chains, not only combine the individual characteristics of their components, but possess various unique structural features and properties as well. In this study, we report on the successful synthesis of a library of polystyrene-l-poly(dimethylsiloxane) (PSt-l-PDMS) (“l” stands for “linked by”) and polystyrene-l-poly(dimethylsiloxane)/divinylbenzene (PSt-l-PDMS/DVB) polymer conetworks. These conetworks were prepared via free radical copolymerization of styrene (St) with methacryloxypropyl-telechelic poly(dimethylsiloxane) (MA-PDMS-MA) as macromolecular crosslinker in the absence and presence of DVB with 36:1 and 5:1 St/DVB ratios (m/m), the latter leading to hypercrosslinked conetworks. Macroscopically homogeneous, transparent conetworks with high gel fractions were obtained over a wide range of PDMS contents from 30 to 80 m/m%. The composition of the conetworks determined by elemental analysis was found to be in good agreement with that obtained from the ¹H NMR spectra of the extraction residues, as a new method which can be widely used to easily determine the composition of multicomponent networks and gels. DSC, SAXS, and AFM measurements clearly indicate bicontinuous disordered nanophase separated morphology for all the investigated conetworks with domain sizes in the range of 3–30 nm, even for the hypercrosslinked PSt-l-PDMS/DVB conetworks with extremely high crosslinking density. The cocontinuous morphology is also proved by selective, composition-dependent uniform swelling in hexane for the PDMS and in 1-nitropropane for the PSt domains. The Korsmeyer–Peppas type evaluation of the swelling data indicates hindered Fickian diffusion of both solvents in the conetwork organogels. The unique nanophasic bicontinuous morphology and the selective swelling behavior of the PSt-l-PDMS and PSt-l-PDMS/DVB conetworks and their gels offer a range of various potential applications. Full article

Strategic utilization of carbon dioxide as both a carbon mitigation tool and a sustainable C1 feedstock represents a pivotal pathway toward green chemistry. Although poly(ionic liquid)s (PILs) exhibit promise in CO₂ conversion, conventional divinylbenzene (DVB) cross-linked architectures are limited by reduced ionic density and limited accessibility of active sites. Herein, we reported a binuclear imidazolium-functionalized PIL catalyst (P-BVIMCl), synthesized through a simple self-polymerization process, derived from rationally designed ionic liquid monomers formed by quaternization of 1,4-bis(chloromethyl)benzene with N-vinylimidazole. The dual active sites in P-BVIMCl-quaternary ammonium cation (N⁺) and nucleophilic chloride anion (Cl⁻) synergistically enhanced CO₂ adsorption/activation and epoxide ring-opening. Under optimal catalyst preparation conditions (100 °C, 24 h, water/ethanol = 1:3 (v/v), 10 wt% AIBN initiator) and reaction conditions (100 °C, 2.0 MPa CO₂, 10 mmol epichlorohydrin, 6.7 wt% catalyst loading, 3.0 h), P-BVIMCl catalyzed the synthesis of glycerol carbonate (GLC) with a yield of up to 93.4% and selectivity of 99.6%, maintaining activity close to 90% after five cycles. Systematic characterization and density functional theory (DFT) calculations confirmed the synergistic activation mechanism. This work established a paradigm for constructing high-ionic-density catalysts through molecular engineering, advancing the development of high-performance PILs for industrial CO₂ valorization. Full article

Passive radar has become very popular in recent years because it is usually undetectable, and countermeasures used to prevent its functioning are complex and, in general, easily identified. Terrestrial digital video broadcasting (DVB-T) is commonly used as an opportunistic illumination signal because of its large range and widespread deployment, both of which make it applicable to almost all scenarios. This paper presents the design of a compact and robust receiver for passive radar that uses a low number of antenna while achieving high accuracy. In order to do this, we use an iterative algorithm to refine the initial estimations based on time-domain channel information to converge to the true estimations. This is especially effective when the signal-to-noise-ratio (SNR) at the receiver is moderate and/or there are several reflections in the environment that may introduce some error into schemes that perform the angle of arrival or time of arrival for the estimation. The algorithm proposed herein is able to accurately estimate the position of a target with a low SNR. Full article

To address the issue of metal corrosion caused by microcracks in the coating on the steel structures of offshore drilling platforms, this study employs interfacial polymerization to prepare microcapsules with self-healing functionality for coatings. The microcapsules are fabricated through free radical polymerization between methyl methacrylate (MMA) and ammonium persulfate (APS), along with crosslinking reactions involving divinylbenzene (DVB). The particle size distribution and surface morphology of the microcapsules were optimized by adjusting process parameters using optical microscopy and scanning electron microscopy. Fourier-transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA) were used to characterize the chemical structure and thermal stability of the microcapsules. The results show that when polyvinyl alcohol is used as the emulsifier, the oil–water ratio was 7.5:200, the amount of emulsifier was 1 wt%, the emulsification speed was 2500 r/min, the amount of initiator was 2 g, the core-to-wall ratio was 4:1, and the ambient temperature was 60 °C showed good sphericity, the microcapsules prepared under the optimized parameters exhibit good sphericity, a smooth surface, and an average particle size of 35.17 μm. They have a good core material encapsulation effect and thermal stability, which impart excellent self-healing properties to the epoxy coating. Such microcapsules have promising applications in mitigating the problem of metal corrosion of coatings due to microcracks and improving the service life and reliability of equipment. Full article

A high-temperature-resistant copolymer thickener (DT) was synthesized through free radical polymerization, utilizing monomers such as N-vinylformamide (NVF), divinylbenzene (DVB), and acrylamide (AM) as the primary raw materials. The polymer system’s structure was characterized using FTIR and 1H NMR, while its thermal properties were analyzed through thermogravimetric analysis. The viscosity changes of the polymers were evaluated before and after high-temperature aging at various temperatures. The results indicated that the viscosity retention rate of the thickener DT in the base slurry at 240 °C and 15% NaCl was 87.1%. Additionally, it exhibited varying anti-aging cycles between 200 °C and 240 °C. In a slurry with 25% NaCl, the viscosity retention rate reached 130% at 200 °C. High-temperature and high-pressure rheological tests demonstrated that drilling fluids containing DT exhibit consistent rheological behavior within the temperature range of 150 °C to 180 °C, which aids in stabilizing the viscosity and strength of drilling fluids at elevated temperatures. Full article

Bacterial contamination is a major public health concern on a global scale. Treatment resistance in bacterial infections is becoming a significant problem that requires solutions. We were interested in obtaining new polymeric functionalized compounds with antibacterial properties. Three components (polymeric amine, aldehyde, and phosphite) were used in the paper in a modified “one-pot” Kabachnik–Fields reaction, in tetrahydrofuran at 60 °C, to create the N-C-P skeleton in aminophosphonate groups. Two copolymers were thus prepared starting from an acrylonitriledivinylbenzene (AN-15%DVB) copolymer containing pendant primary amine groups modified by grafting aminophosphonate groups, i.e., aminobenzylphosphonate (Bz-DVB-AN) and aminoethylphosphonate (Et-DVB-AN). The two copolymers were characterized by FT-IR spectroscopy, SEM-EDX, TGA, and antibacterial properties. It was shown that the novel products have antibacterial qualities against S. aureus and E. coli bacteria. The sample with the strongest antibacterial activity was Et-DVB-AN. We assessed how well the Weibull model and the first-order kinetic model represent the inactivation of microbial cells in our samples. The main advantage of the new antibacterial agents developed in this work is their easy recovery, which helps to avoid environmental contamination. Full article

The contamination of water by heavy metals poses an escalating risk to human health and the environment, underscoring the critical need for efficient removal methods to secure safe water resources. This study evaluated the performance of four cationic exchange materials (labeled “PS—DVB”, “PA—DVB”, “TFSA”, and “OGL”) in removing or harvesting metals such as copper, silver, lead, cobalt, and nickel from aqueous solutions, several of which are precious and/or classified as Critical Raw Materials (CRMs) due to their economic importance and supply risk. The objective was to screen and benchmark the four ion exchange materials for water treatment applications by investigating their metal sequestration capacities. Experiments were conducted using synthetic solutions with controlled metal concentrations, analyzed through ICP-OES, and supported by kinetic modeling. The adsorption capacities (qe) obtained experimentally were compared with those predicted by pseudo-first-order and pseudo-second-order models. This methodology enables high precision and reproducibility, validating its applicability for assessing ion exchange performance. The results indicated that PS—DVB and PA—DVB resins proved to be of “wide range”, exhibiting high efficacy for most of the metals tested, including CRM-designated ones, and suggesting their suitability for water purification. Additionally, the second-life Nafion-based “TFSA” material demonstrated commendable performance, highlighting its potential as a viable and technologically advanced alternative in water treatment. Lastly, the lignin-based material, “OGL”, representing the most innovative and sustainability apt option, offered relevant performance only in selected cases. The significant differences in performance among the resins underscore the impact of structural and compositional factors on adsorption efficiency. This study offers valuable insights for investigating and selecting new sustainable materials for treating contaminated water, opening new pathways for targeted and optimized solutions in environmental remediation. Full article

Background/Objectives: Biogenic volatile organic compounds (BVOCs), extensively studied in terrestrial plants with global emissions around 1 PgC yr⁻¹, are also produced by marine organisms. However, benthic species, especially seagrasses, are understudied despite their global distribution (177,000–600,000 km²). This study aims to examine BVOC emissions from key Mediterranean seagrass species (Cymodocea nodosa, Posidonia oceanica, Zostera noltei, and Zostera marina) in marine and coastal lagoon environments. Methods: BVOCs were collected using headspace solid-phase microextraction (HS-SPME) using divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fibers and analyzed by gas chromatography–mass spectrometry (GC-MS). Results: An important chemical diversity was found with a total of 92 volatile compounds (61 for Z. noltei, 59 for C. nodosa, 55 for P. oceanica, and 51 for Z. marina), from different biosynthetic pathways (e.g., terpenoids, benzenoids, and fatty acid derivatives) and with several types of chemical functions (e.g., alkanes, esters, aldehydes, and ketones) or heteroatoms (e.g., sulfur). No differences in chemical richness or diversity of compounds were observed between species. The four species shared 29 compounds enabling us to establish a specific chemical footprint for Mediterranean marine plants, including compounds like benzaldehyde, benzeneacetaldehyde, 8-heptadecene, heneicosane, heptadecane, nonadecane, octadecane, pentadecane, tetradecane, and tridecanal. PLS-DA and Heatmap show that the four species presented significantly different chemical profiles. The major compounds per species in relative abundance were isopropyl myristate for C. nodosa (25.6%), DMS for P. oceanica (39.3%), pentadecane for Z. marina (42.9%), and heptadecane for Z. noltei (46%). Conclusions: These results highlight the potential of BVOCs’ emission from seagrass ecosystems and reveal species-specific chemical markers. Full article