Search Results (26,657)

Anionic thermo- and pH-responsive copolymers were synthesized by photoiniferter reversible addition–fragmentation chain transfer polymerization (PI-RAFT). The thermo-responsive properties were provided by oligo(ethylene glycol)-based macromonomer units containing hydrophilic and hydrophobic moieties. The pH-responsive properties were enabled by the addition of 5–20 mol% of strong (2-acrylamido-2-methylpropanesulfonic) and weak (methacrylic) acids. Upon initiation by visible light at 470 nm and in the absence of radical initiators, yields from the ternary copolymers reached 94% in 2.5 h when the process was carried out in continuous flow mode using 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid as a light-sensitive RAFT agent. The polymers were characterized using size exclusion chromatography, IR and NMR spectroscopy, and differential scanning calorimetry. The copolymers featured a sufficiently high molecular weight (93–146 kDa) consistent with theoretical values and satisfactory dispersities in the range of 1.18–1.45. The pH-responsive properties were studied in deionized water, saline, and buffer solutions. Dramatic differences in LCST behavior were observed in strong and weak acid-based polyelectrolytes. The introduction of sulfonic acid units, even in very small amounts, completely suppressed the LCST transition in deionized water while maintaining it in the saline and buffer solutions, with a negligible LCST dependence on the pH. In contrast, the incorporation of weak methacrylic acid demonstrated a pronounced pH dependence. The peculiarities of micelle formation in aqueous solutions were investigated and critical micelle concentrations and their ability to retain pyrene, a hydrophobic drug model, were determined. It was observed that anionic molecular brushes formed small micelles with aggregation numbers of 1–2 at concentrations in the order of 10⁻⁴ mg/mL. These micelles have a high ability to entrap pyrene, which makes them a promising tool for targeted drug delivery. Full article

In recent years, significant advancements have been made in the field of brain–computer interfaces (BCIs), particularly in the area of emotion recognition using EEG signals. The majority of earlier research in this field has missed the spatial–temporal characteristics of EEG signals, which are critical for accurate emotion recognition. In this study, a novel approach is presented for classifying emotions into three categories, positive, negative, and neutral, using a custom-collected dataset. The dataset used in this study was specifically collected for this purpose from 16 participants, comprising EEG recordings corresponding to the three emotional states induced by musical stimuli. A multi-class Common Spatial Pattern (MCCSP) technique was employed for the processing stage of the EEG signals. These processed signals were then fed into an ensemble model comprising three autoencoders with Convolutional Neural Network (CNN) layers. A classification accuracy of 99.44 ± 0.39% for the three emotional classes was achieved by the proposed method. This performance surpasses previous studies, demonstrating the effectiveness of the approach. The high accuracy indicates that the method could be a promising candidate for future BCI applications, providing a reliable means of emotion detection. Full article

This study investigates the structural, vibrational, and biological properties of novel palladium(II) and platinum(II) complexes with 5-chloro-7-azaindole-3-carbaldehyde (5ClL) and 4-chloro-7-azaindole-3-carbaldehyde (4ClL) ligands. Infrared and Raman spectroscopy, combined with DFT (ωB97X-D) calculations, provided valuable information about metal–ligand interactions, the cis or trans conformation of the aldehyde group in the ligands, and the presence of trans isomers in the metal complexes obtained in the solid state. In vitro tests were used to evaluate the antiproliferative activity of the novel complexes against several cancer cell lines, including ovarian cancer (A2780), cisplatin-resistant ovarian cancer (A2780cis), colon cancer (HT-29), and triple-negative breast cancer (MDA-MB-231), as well as normal mouse fibroblasts (BALB/3T3). The platinum complex, trans-[PtCl₂(5ClL)₂], exhibited superior activity against A2780cis (IC₅₀ = 4.96 ± 0.49 µM) and MDA-MB-231 (IC₅₀ = 4.83 ± 0.38 µM) compared to cisplatin, while the palladium complexes (trans-[PdCl₂(4ClL)₂] and trans-[PdCl₂(5ClL)₂]) demonstrated enhanced selectivity with reduced toxicity to normal fibroblasts (IC₅₀ = 11.29 ± 6.65 µM and 14.98 ± 5.59 µM, respectively). Full article

Here, we report a numerical study of supercontinuum generation in an antiresonant optical fiber with a hollow core filled with a mixture of deuterium (D₂) and hydrogen (H₂). For 1 ps pulses at a wavelength of 1.03 μm with different chirp values, we demonstrate a possibility of obtaining a mid-IR coherent supercontinuum with a spectral width of 2300 nm, initiated by cascade processes at resonance frequencies of vibrational and rotational levels of D₂ and H₂. We show that an increase in the chirped pulse duration to 25 ps while maintaining the energy and spectral width allows increasing the quantum conversion efficiency in the mid-IR from 10 to 50% and expanding the range of optimal fiber lengths at which a high degree of supercontinuum coherence is achieved. Full article

In this paper, we explore intelligent reflecting surface (IRS)-assisted physical layer security (PLS) in a wireless-powered Internet of Things (IoT) network (WPIN) by combining an IRS, a friendly jammer, and energy harvesting (EH) to maximize sum secrecy throughput in the WPIN. Specifically, we propose a non-line-of-sight system where a hybrid access point (H-AP) has no direct link with the users, and a secure uplink transmission scheme utilizes the jammer to combat malicious eavesdroppers. The proposed scheme consists of two stages: wireless energy transfer (WET) on the downlink (DL) and wireless information transmission (WIT) on the uplink (UL). In the first phase, the H-AP sends energy to users and the jammer, and they then harvest energy with the help of the IRS. Consequently, during WIT, the user transmits information to the H-AP while the jammer emits signals to confuse the eavesdropper without interfering with the legitimate transmission. The phase-shift matrix of the IRS and the time allocation for DL and UL are jointly optimized to maximize the sum secrecy throughput of the network. To tackle the non-convex problem, an alternating optimization method is employed, and the problem is reformulated into two sub-problems. First, the IRS phase shift is solved using quantum particle swarm optimization (QPSO). Then, the time allocation for DL and UL are optimized using the bisection method. Simulation results demonstrate that the proposed method achieves significant performance improvements as compared to other baseline schemes. Specifically, for IRS elements N = 35, the proposed scheme achieves a throughput of 19.4 bps/Hz, which is 85% higher than the standard PSO approach and 143% higher than the fixed time, random phase (8 bps/Hz) approach. These results validate the proposed approach’s effectiveness in improving network security and overall performance. Full article

Tire wear particles (TWPs) are among the most relevant sources of microplastic pollution of the environment. Nevertheless, common analytical methods like IR and Raman spectroscopy are highly impaired by additives and filler materials, leaving only thermogravimetric methods for chemical analysis of TWPs in most cases. We herein present quantitative NMR spectroscopy (qNMR) as an alternative tool for the quantification of the polymeric material used for the production of tires, including natural rubber (NR), styrene–butadiene–copolymer (SBR), polyethylene–co-propylene (EPR) and polybutadiene (BR). Limits of quantification (LOQ) between 3 µg and 43 µg per sample and recovery rates of 72–92% were achieved for all tested polymer types. The first results of combining these measurements with Soxhlet extraction as a sample preparation tool are presented alongside the qNMR experiments. Full article

We calculated the two-loop corrections in the primordial power spectrum in models of single-field inflation incorporating an intermediate USR phase employed for PBH formation. Among the overall eleven one-particle irreducible Feynman diagrams, we calculated the corrections from the “double scoop” two-loop diagram involving two vertices of quartic Hamiltonians. We demonstrate herein the fractional two-loop correction in power spectrum scales, like the square of the fractional one-loop correction. We confirm our previous findings that the loop corrections become arbitrarily large in the setup where the transition from the intermediate USR to the final slow-roll phase is very sharp. This suggests that in order for the analysis to be under perturbative control against loop corrections, one requires a mild transition with a long enough relaxation period towards the final attractor phase. Full article

Accurate crop yield estimation is critical to successful agricultural operations. Current crop growth models often overlook the spatial and geographic components of the lands, leading to suboptimal yield estimates. To address this issue, assimilation of satellite vegetation products into these models can account for spatial variations in the land and improve estimation accuracy. In this paper, the AquaCrop model, a water-driven crop growth model, was selected for recalibration and assimilation of satellite-derived biophysical products due to its simplicity and lack of computational complexity. To this end, field samples of soil (sampled before cultivation) and crop features were collected during the growing season of silage maize. Digital hemisphere photography (DHP) and destructive sampling methods were used for measuring fraction vegetation cover (fCover) and biomass in Qaleh-Now County, southern Tehran, in 2019. Based on our proposed workflow in previous studies, a Gaussian process regression–particle swarm optimization (GPR-PSO) algorithm and global sensitivity analysis were applied to retrieve the fCover and biomass from Sentinel-2 satellite data and to identify the most sensitive parameters in the AquaCrop model, respectively. Here, we propose the use of an optimization water cycle algorithm (WCA) instead of a PSO algorithm as an assimilation method for the parameter calibration of AquaCrop. This study also focused on using both fCover and biomass state variables simultaneously in the model, as opposed to only the fCover, and found that using both variables led to significantly higher calibration accuracy. The WCA method outperformed the PSO method in AquaCrop’s calibration, leading to more accurate results on maize yield estimates. It has enhanced results, decreasing RMSE values by 3.8 and 4.7 ton/ha, RRMSE by 6.4% and 10%, and increasing R² by 0.17 and 0.35 for model calibration and validation, respectively. These results suggest that assimilating satellite-derived data and optimizing the calibration process through WCA can significantly improve the accuracy of crop yield estimations in water-driven crop growth models, highlighting the potential of this approach for precision agriculture. Full article

Elevated levels of reactive oxygen species (ROS) are caused by ultraviolet B radiation (UV-B) stress. In response, plants strengthen their cell membranes, impeding photosynthesis. Additionally, UV-B stress initiates oxidative stress within the antioxidant defense system and alters secondary metabolism, particularly by increasing the quantity of UV-absorbing compounds such as flavonoids. The v-myb avian myeloblastosis viral oncogene homolog (MYB) transcription factor (TF) may participate in a plant’s response to UV-B damage through its regulation of flavonoid biosynthesis. In this study, we discovered that the photosynthetic activity of Rhododendron chrysanthum Pall. (R. chrysanthum) decreased when assessing parameters of chlorophyll (PSII) fluorescence parameters under UV-B stress. Concurrently, antioxidant system enzyme expression increased under UV-B exposure. A multi-omics data analysis revealed that acetylation at the K68 site of the RcTRP5 (telomeric repeat binding protein of Rhododendron chrysanthum Pall.) transcription factor was upregulated. This acetylation modification of RcTRP5 activates the antioxidant enzyme system, leading to elevated expression levels of peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT). Upregulation is also observed at the K95 site of the chalcone isomerase (CHI) enzyme and the K178 site of the anthocyanidin synthase (ANS) enzyme. We hypothesize that RcTRP5 influences acetylation modifications of CHI and ANS in flavonoid biosynthesis, thereby indirectly regulating flavonoid production. This study demonstrates that R. chrysanthum can be protected from UV-B stress by accumulating flavonoids. This could serve as a useful strategy for enhancing the plant’s flavonoid content and provide a valuable reference for research on the metabolic regulation mechanisms of other secondary substances. Full article

Nano metakaolin (NMK) has attracted considerable interest for its potential to improve the durability of cementitious materials. However, the effect of NMK on the splitting tensile performance of concrete has not been systematically investigated. This study investigates the splitting tensile performance of NMK concrete and analyzes its failure behavior under splitting load. Different NMK dosages (0%, 1%, 3%, 5%, and 7%) were considered, and splitting tensile tests were conducted. The crack propagation process, crack width, and crack growth rate on the surface of NMK concrete during the splitting tensile test are analyzed using the Digital Image Correlation (DIC) method. The mechanisms by which NMK affects the splitting tensile performance of concrete were examined using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy/Energy Dispersive Spectroscopy (SEM/EDS), and Thermogravimetric Analysis (TG). The results indicate that the incorporation of NMK enhances the splitting tensile performance of concrete. Concrete with 5% NMK addition exhibited the highest splitting tensile strength, with an increase of 17.4% compared to ordinary concrete. NMK improved the cracking resistance and overall integrity under splitting tensile load. With 5% NMK addition, the surface crack length, width, and main crack propagation rate of the concrete decreased by 4.5%, 35.3%, and 29.6%, respectively. NMK contributed to a denser internal structure of the concrete, promoted the formation of C-S-H gel, and increased the degree of cement hydration. Moreover, a lower thickness and Ca/Si ratio of interfacial transition zone (ITZ) were observed in NMK concrete. The ITZ thickness and Ca/Si ratio of concrete with 5% NMK were reduced by 64.4% and 85.4%, respectively, compared to ordinary concrete. In summary, the influence mechanism of NMK addition on the splitting tensile strength and failure behavior of concrete is explored in this study, providing experimental data to support the application of NMK concrete in practical engineering. Full article

Background: The clinical efficacies of anticancer drugs are limited by non-selective toxic effects on healthy tissues and low bioavailability in tumor tissue. Therefore, the development of vehicles that can selectively deliver and release drugs at the tumor site is critical for further improvements in patient survival. Methods: We prepared a CEC nano-drug delivery system, CEC@ZIF-8, with a zeolite imidazole framework-8 (ZIF-8) as a carrier, which can achieve the response of folate receptor (FR). We characterized this system in terms of morphology, particle size, zeta potential, infrared (IR), x-ray diffraction (XRD), and transcriptome analysis, and examined the in vitro cytotoxicity and cellular uptake properties of CEC@ZIF-8 using cervical cancer cells. Lastly, we established a TC-1 tumor-bearing mouse model and evaluated its in vivo anti-cervical cancer activity. Results: The CEC@ZIF-8 nano-delivery system had favorable biocompatibility, heat stability, and pH responsiveness, with a CEC loading efficiency of 12%, a hydrated particle size of 174 ± 5.8 nm, a zeta potential of 20.57 mV, and slow and massive drug release in an acidic environment (pH 5.5), whereas release was 6% in a neutral environment (pH 7.4). At the same time, confocal imaging and cell viability assays demonstrated greater intracellular accumulation and more potent cytotoxicity against cancer cells compared to free CEC. The mechanism was analyzed by a series of transcriptome analyses, which revealed that CEC@ZIF-8 NPs differentially regulate the expression levels of 1057 genes in cancer cells, and indicated that the enriched pathways were mainly cell cycle and apoptosis-related pathways via the enrichment analysis of the differential genes. Flow cytometry showed that CEC@ZIF-8 NPs inhibited the growth of HeLa cells by arresting the cell cycle at the G0/G1 phase. Flow cytometry also revealed that CEC@ZIF-8 NPs induced greater apoptosis rates than CEC, while unloaded ZIF-8 had little inherent pro-apoptotic activity. Furthermore, the levels of reactive oxygen species (ROS) were also upregulated by CEC@ZIF-8 NPs while ROS inhibitors and caspase inhibitors reversed CEC@ZIF-8 NPs-induced apoptosis. Finally, CEC@ZIF-8 NPs also reduced the growth rate of xenograft tumors in mice without the systemic toxicity observed with cisplatin treatment. Conclusions: The CEC@ZIF-8 nano-drug delivery system significantly enhanced the anti-cervical cancer effect of CEC both in vivo and in vitro, providing a more promising drug delivery system for clinical applications and tumor management. At the same time, this work demonstrates the clinical potential of CEC-loaded ZIF-8 nanoparticles for the selective destruction of tumor tissues. Full article

Infrared (IR) radiation curing technology has a high potential to improve the curing process of thermosetting polymers. To investigate the IR curing reaction mechanism, the present study explores the curing kinetics of glycidyl methacrylate (GMA)/dodecanedioic acid (DDDA) powder coatings subjected to IR radiation. Fourier-transformed infrared (FT-IR) spectroscopy is employed to record the concentration of epoxide groups with respect to time under different temperature conditions, with the reaction conducted under IR radiation. The resulting data are then fitted by the Levenberg–Marquardt algorithm using MATLAB software to obtain the kinetic parameters, namely the rate constant (k), catalytic constants (n, m), manifestation activation energy (E), and the pre-exponential factor (A) of the curing reaction. Additionally, this study proposes a new concept: the ‘photo-thermal synergistic effect’ of infrared curing and its evaluation criteria using a dimensionless quantity. Incredibly, this index integrates the impact of IR curing technology on two aspects: the curing process and the properties of the cured product. Overall, this study deepens our understanding of the IR curing reaction mechanism and provides a reference for the application of this technology in practical engineering. Full article

A multipronged approach to the refined mechanochemical synthesis of the semiconductor kesterite Cu₂ZnSnS₄ with minimal quantities of adventitious oxygen as well as to optimizing handling procedures from that angle is described. Three precursor systems are used to provide a pool of freshly made cubic prekesterite nanopowders with no semiconductor properties and the thermally annealed at 500 °C tetragonal kesterite nanopowders of the semiconductor. Based on the previously reported high propensity of such nanopowders to long-term deteriorating oxidation in ambient air, suitable modifications of all crucial synthesis steps are implemented, which are directed toward excluding or limiting the materials’ exposure to air. The nanopowders are comprehensively characterized by powder XRD, FT-IR/Raman/UV-Vis spectroscopies, solid-state ⁶⁵Cu/¹¹⁹Sn MAS NMR, TGA/DTA-QMS analysis, SEM, BET/BJH specific surface area, and helium density determinations, and, significantly, are directly analyzed for oxygen and hydrogen contents. The important finding is that following the anaerobic procedures and realistically minimizing the materials’ exposure to air in certain manipulation steps results in the preparation of better oxidation-resistant nanopowders with a dramatic relative decrease in their oxygen content than previously reported. The adherence to the strict synthesis conditions that limit contact of the no-oxygen-containing kesterite nanopowders with ambient air is emphasized. Full article

Endohedral metallo-borospherenes M@B₄₀ have received considerable attention since the discovery of B₄₀ in 2014. However, the coordination bonding nature of most of actinide-doped endohedral An@B₄₀ still remains in dispute or unexplored. Extensive and systematic first-principles theory calculations performed herein unveil the ground states of triplet U@B₄₀ (1, C_2v, ³A₂), quartet U@B₄₀⁻ (2, C_2v, ⁴B₁), quintet Np@B₄₀⁺ (3, C_2v, ⁵A₁), sextet Np@B₄₀ (4, C₂, ⁶A), septet Pu@B₄₀ (5, C_2v, ⁷A₂), octet Am@B₄₀ (6, C_2v, ⁸A₂), and octet Cm@B₄₀⁺ (7, C_2v, ⁸A₂) at the coupled-cluster with triple excitations CCSD(T) level. Detailed principal interacting spin orbital (PISO) and adaptive natural density partitioning (AdNDP) analyses reveal their coordination bonding patterns and show that, with the numbers of unpaired α-electrons in parallel spins varying from n_α = 2, 3, 4, 5, 6, 7, to 7 in these complexes, the percentage contribution of the An 5f-involved PISO pairs to overall coordination bonding interactions decreases monotonously from 41% to 1%, and the contribution of An 6d-involved PISO pairs increases monotonously from 47% to 72%, while the marginal contribution of An 7s-involved PISO pairs remains basically unchanged (4~7%). The IR, Raman, and photoelectron spectra of the most concerned species are computationally simulated to facilitate their characterizations in future experiments. Full article

African swine fever (ASF) is a lethal disease of domestic pigs that is currently challenging swine production in large areas of Eurasia. The causative agent, ASF virus (ASFV), is a large, double-stranded and structurally complex virus. The ASFV genome encodes for more than 160 proteins; however, the functions of most of these proteins are still in the process of being characterized. The ASF gene R298L, which has previously been characterized as able to encode a functional serine protein kinase, is expressed late in the virus infection cycle and may be part of the virus particle. There is no description of the importance of the R298L gene in basic virus functions such as replication or virulence in the natural host. Based on its evolution, it is proposed that there are four different phenotypes of R298L of ASFV in nature, which may have potential implications for R298L functionality. We report here that a recombinant virus lacking the R298L gene in the Georgia 2010 isolate, ASFV-G-∆R298L, does not exhibit significant changes in its replication in primary cultures of swine macrophages. In addition, when experimentally inoculated in pigs, ASFV-G-∆R298L induced a fatal form of the disease similar to that caused by the parental virulent ASFV-G. Therefore, deletion of R298L does not significantly affect virus replication and virulence in domestic pigs of the ASFV Georgia 2010 isolate. Full article