Search Results (127)

Nuclear relaxation, $1/T_1$, is a very robust probe of electronic excitations in superconducting materials above and below the critical temperature of superconductivity, $T_{\mathrm{c}}$. Here, a relaxation phenomenology of hole-doped cuprate superconductors is presented based on the majority of the available literature data from the CuO₂ plane, without assumptions with respect to a hyperfine scenario, form factors, or particular theoretical models. Below a temperature similar to the pseudogap temperature, Heitler–Teller-type relaxation is uncovered universally; i.e., the nuclear spin relaxation above $T_{\mathrm{c}}$ is only determined by the absolute temperature, $1/T_1\propto T$. All materials condense out of this metal at $T_{\mathrm{c}}$, below which relaxation drops even faster, as expected from conventional superconductors, albeit without a Hebel–Slichter peak. It is a ’hidden metal’ in the sense that it has a vanishing uniform response and thus hardly affects the NMR shifts; it is also not seen in planar O relaxation. The hidden metal causes a temperature-independent but material-dependent planar Cu relaxation anisotropy that is strongly correlated with the size of $T_{\mathrm{c}}$. Moreover, the rate measured with the field in the CuO₂ plane is nearly the same for all cuprates: $1/{{}^{63}T}_{1\perp }T\approx 25/$Ks, where $1/{{}^{63}T}_{1\Vert }$ is mainly responsible for the change in anisotropy. Above the hidden metal, the relaxation behavior changes and can be described by an ordinary but renormalized metal, with a reduced Cu relaxation anisotropy. The relaxation phenomenology, which should hold clues to the so-called strange metal, is also discussed in the context of the two spin components previously uncovered in the shifts, as well as the pseudogap and relation to other probes. This new phenomenology should give a better foundation for the understanding of the cuprates. Full article

In this work, the structural, mechanical, electronic, and optical properties of the 18-valence-electron half-Heusler compounds MCoBi (M = Ti, Zr, Hf) are investigated using the all-electron full-potential linearized augmented plane wave (FP-LAPW) method. The relativistic effect of spin–orbit coupling (SOC) is systematically incorporated and analyzed. Structural optimization confirms the stability of the Type-III phase, with lattice parameters in good agreement with available experimental data. Mechanically, the inclusion of SOC reduces both stiffness and brittleness, indicating a clear softening effect on the material behavior. SOC significantly lifts the degeneracy of the electronic bands, resulting in splitting (Δ_SO) at the valence band maximum of approximately 0.10 eV and 0.12 eV for TiCoBi and ZrCoBi, respectively, which subsequently reduces the band gap; however, HfCoBi exhibits a remarkably weak splitting. The impact of SOC is further evidenced in the optical response across all three compounds. The absorption coefficient reaches high values (>${10}^5 {\mathrm{c}\mathrm{m}}^{-1}$) in the visible spectrum. Furthermore, a dramatic reduction in the intensity of plasmon resonance frequencies is observed, with values dropping to approximately 0.10–0.11 for the studied compounds. These findings highlight the potential of these materials for future electronic and optoelectronic device applications. Full article

Aiming at two core problems in data poisoning attack detection, namely the lack of formal modeling and the insufficient guarantee of theoretical completeness, this paper proposes a model checking-driven formal verification algorithm for poisoning attacks. First, the AI system is abstracted into a quadruple, and poisoning attacks (label flipping, feature perturbation, backdoor poisoning, gradient tampering) are modeled as a triple. Meanwhile, CTL* and PCTL temporal logic formulas are adopted to characterize the features of the above attacks, respectively. Second, equivalent mapping from formal features to logic formulas is established by constructing atomic propositions and Kripke structures, and automated detection and verification are realized based on the SPIN and PRISM tools. Furthermore, three core theorems are proposed and strictly proved: the characterization completeness theorem of the formal model for poisoning attacks, the completeness and correctness theorem of the detection algorithm, and the robustness theorem of the defense framework. Theoretical proofs and experimental results demonstrate that, when the proportion of malicious samples is no more than 20%, the missing detection rate is ≤2% and the false detection rate is ≤3.5%. After defense deployment, the accuracy drop of the model is controlled within 8%. This work provides a formally verifiable and theoretically guaranteed solution for poisoning attack detection in AI systems. Full article

The bio-based biodegradable material poly(L-lactic acid) (PLLA) has received extensive attention due to its inherent sustainability. Ultra-high molecular weight (UHMW) PLLA possesses superior physical, chemical, and mechanical properties, but its difficulty in processing often restricts its further application. In this work, efficient preparation of UHMW PLLA fiber membranes using electro-blown spinning technology was reported for the first time. Thanks to the excellent electrostatic adsorption capacity brought by the piezoelectric properties of the prepared fiber membrane and its fluffy multi-scale structure, it demonstrates outstanding air filtration performance. The contradiction between filtration efficiency (>99.8% for PM_0.3) and pressure drop (~16 Pa) has been successfully balanced. It also demonstrated excellent moisture resistance, long-term stability, and dust-holding capacity. Especially compared with low molecular weight PLLA fiber membranes, the air filtration performance of UHMW PLLA fiber membranes have demonstrated excellent chemical stability. Meanwhile, its temperature stability can also meet the needs of most scenarios in life. This ensures the feasibility of practical application of the sustainable material PLLA in the field of air filtration. And due to its excellent filtration performance, it reduces energy consumption during use, thereby achieving sustainable development throughout the material’s entire life cycle. Full article

Photothermal superhydrophobic surfaces represent a promising solution for passive anti-icing; however, the persistent high solar absorption of static black coatings often leads to undesirable overheating under non-icing conditions. To address this limitation, we developed a smart superhydrophobic polydimethylsiloxane (PDMS) surface embedded with thermochromic capsules (TC) (S-PDMS/TC) featuring reversible thermochromic capability via a facile combination of spin-coating and femtosecond laser ablation. The resulting hierarchical micro-grid structure acts as a sacrificial layer, shielding fragile nanostructures against mechanical abrasion, while endowing the surface with robust superhydrophobicity (contact angle > 155°). Uniquely, S-PDMS/TC exhibits an adaptive color transition from pale yellow to deep black when the temperature drops below 5 °C. This response enables on-demand photothermal enhancement, significantly boosting solar absorption in freezing environments while minimizing heat absorption at room temperature. Consequently, S-PDMS/TC demonstrates superior anti-icing performance, extending the freezing time to 310 s and reducing ice adhesion strength to 40.4 kPa. Notably, during photothermal de-icing, the meltwater exhibits spontaneous dewetting behavior driven by the replenishment of the air cushion, effectively preventing secondary icing. This work presents a mechanically durable and intelligent strategy for ice protection, successfully balancing efficient de-icing with thermal management. Full article

Wind-assisted ship propulsion (WASP) systems are gaining importance due to their contribution to reducing greenhouse gases and saving fuel. Existing studies mostly focus on the aerodynamics of sailing systems, the integration of sails and ship dynamics, and the prediction of fuel savings. The present study extends the use case of sailing systems by proposing a new control logic that improves maneuvering performance. Determining the spin ratio of rotor sails not only with thrust but also with side forces and moments is also included as an objective function. Using numerous random weights for each term and environmental conditions, the turning performance of the target ship was evaluated. Then, an artificial neural network (ANN) model was trained to decide on the optimal weights, depending on the environmental conditions. Finally, the performance of the new control approach was evaluated based on turning and zigzag test simulations. It was found that the advance, transfer, and tactical diameters dropped by up to 5%, 7% and 7%, respectively, compared to those of a conventional ship. When it comes to the zigzag performance, it was revealed that the overshoot angles dropped even though there was no simulation data about zigzag tests in the trained ANN model. Thus, it was shown that sails improve the maneuverability of ships in addition to providing additional thrust if a proper control approach is adopted. Full article

Unmanned aerial vehicles (UAVs) are an alternative to traditional pesticide applications in orchards. Particularly, drones are an example of UAVs that have increased in popularity in recent years; however, relatively few studies have evaluated how spraying operation modes interact with other drone parameters within a single experimental framework. This study evaluated the effects of operation mode, application volume, flight height, and droplet size on spray coverage, droplet density, droplet spectra, and droplet size uniformity using the spraying drone DJI Agras T40 under a simulated canopy structure. A four-factorial experimental design was used; treatments included three operation modes (i.e., standard mode, fruit-tree mode, and spinning mode), two application volumes (i.e., 37.4 L/ha and 74.8 L/ha), two flight heights (i.e., 3 m and 5 m), and two droplet sizes (i.e., 150 μm and 300 μm). Operation mode was among the most influential factors affecting spray deposition quality. The spinning mode achieved the highest overall spray coverage (20.81%) and droplet density (172.44 drops/cm²), while the standard mode provided the most uniform spatial distribution. Results from the interaction analyses indicated that the parameter combination that produced the highest spray coverage within the tested ranges was an application volume of 74.8 L/ha, a flight height of 3 m, and a droplet size of 150 μm in the standard mode. For the fruit-tree mode, the highest spray coverage was observed at an application volume of 74.8 L/ha, a flight height of 5 m, and a droplet size of 300 μm. For the spinning mode, the combination associated with the highest spray coverage was 74.8 L/ha, 3 m, and 300 μm. In conclusion, the results provide data-driven guidance on how drone operational parameters influence spray deposition and can support future validation under commercial orchard conditions. Full article

High-temperature particulate matter (PM) filtration remains a fundamental challenge, because most fiber filters not only face the challenge of high temperatures but also suffer from an inherent trade-off between capture efficiency, pressure drop, and service life. This paper reports a hierarchical layered zirconia (ZrO₂) ceramic fiber aerogel featuring a continuous multiscale gradient. The aerogel was prepared by gradient air-blown spinning, and the resulting structure has directional order, with the fiber diameter gradually decreasing from upstream to downstream, thus forming a pore size gradient and achieving hierarchical particle interception across multiple scales. This rational design simultaneously suppresses surface clogging and reduces flow resistance, resolving the longstanding trade-off between efficiency and permeability. Consequently, this aerogel achieves an ultra-high filtration efficiency of 99.96%, a low pressure drop of 156 Pa, and a high dust-holding capacity of 101 g m⁻². The material also exhibits outstanding mechanical toughness (80% compressive strain elasticity and 25.75% tensile fracture strain) and thermal stability up to 1000 °C. Moreover, it maintains over 99.95% filtration efficiency at high temperatures and can be fully regenerated through 800 °C heat treatment. This work establishes a structure-based design paradigm for high-temperature filtration media and provides a scalable pathway for next-generation industrial flue gas purification. Full article

This study investigates the development and characterization of bioactive films incorporating silver nanoparticles (AgNPs) into biocompatible polymers, namely alginate and chitosan, fabricated using two methods, spin-coating and drop-casting, and aiming to enhance their antimicrobial properties. Dynamic light scattering (DLS) and electrophoretic mobility (EM) of the film precursor solutions revealed significant changes in the nanoparticles’ size and Zeta potential (ZP), reflecting the influence of polymer coatings. Alginate contributed to high electrostatic stability due to its negative charge, while chitosan facilitated specific interactions with negatively charged surfaces. Raman spectroscopy revealed that spin-coating conditions did not successfully result in film formation, highlighting the need for further optimization. Therefore, subsequent characterization studies were conducted only for the films formed by drop-casting. Topographical and nanomechanical assessments of these drop-cast films, using atomic force microscopy (AFM) and force spectroscopy, demonstrated that AgNPs reduced adhesion and elasticity in alginate films, while increasing rigidity and adhesion in chitosan-based films. Antimicrobial tests confirmed the efficacy of AgNPs in both precursor solutions and polymer films, with chitosan-based films that retained structural integrity, which makes them suitable for prolonged applications, while alginate films displayed rapid gelation upon hydration, potentially advantageous in short-term applications. The findings underscore the potential of these biopolymer-AgNP composites in creating antimicrobial materials for food packaging, wound dressings, and other biomedical applications. However, challenges related to film deposition methods, such as spin-coating, require further optimization to improve film formation and reproducibility. Full article

Background: Non-absorbable polyvinyl alcohol sponges (Merocel) are widely used in otolaryngology for nasal and ear packing but are prone to bacterial colonization and biofilm formation, which may increase infection risk and drive frequent use of systemic antibiotics. Sustained-release drug delivery systems enable prolonged local antiseptic activity at the site of packing while minimizing systemic exposure. Methods: We developed a sustained-release varnish containing chlorhexidine (SRV-CHX) and coated sterile Merocel sponges. Antibacterial, in vitro, activity against Staphylococcus aureus and Pseudomonas aeruginosa was evaluated using kinetic diffusion assays on agar, optical density (OD₆₀₀) measurements of planktonic cultures, drop plate, ATP-based viability assays, biofilm analysis by MTT metabolic assay, crystal violet bio-mass staining, high-resolution scanning electron microscopy (HR-SEM), and spinning disk confocal microscopy. Results: SRV-CHX-coated sponges produced sustained zones of inhibition on agar plates for up to 37 days against S. aureus and 39 days against P. aeruginosa, far exceeding the usual 3–5 days of clinical sponge use. Planktonic growth was significantly reduced compared with SRV-placebo, and a bactericidal effect persisted for up to 16 days for S. aureus and 5 days for P. aeruginosa before becoming predominantly bacteriostatic. Biofilm formation was markedly inhibited, with suppression of metabolic activity and biomass for at least 33 days for S. aureus and up to 16 days for P. aeruginosa. HR-SEM and confocal imaging confirmed sparse, discontinuous biofilms and predominance of non-viable bacteria on SRV-CHX-coated sponges compared with dense, viable biofilms on the placebo controls. Conclusions: Coating Merocel sponges with SRV-CHX provides prolonged antibacterial and anti-biofilm activity against clinically relevant pathogens. This strategy may reduce dependence on systemic antibiotics and improve infection control in nasal and ear packing applications in otolaryngology. Full article

Objectives: Oxidative stress after cardiac surgery may disrupt the blood–brain barrier and contribute to postoperative delirium (POD). Although associations between oxidative stress and POD are recognized, whether vitamin C (VC) can prevent POD remains poorly understood. This study aimed to explore the association of VC administration with POD after cardiac surgery. Methods: Eighty-four patients undergoing elective cardiac surgery at our hospital were enrolled. The non-VC group (NVC, n = 40) consisted of patients treated between October 2021 and March 2022, while the VC group (n = 44) included those treated between April and September 2022 who received 2 g intravenous VC at intensive care unit (ICU) admission. The primary outcome was POD incidence. Electron spin resonance (ESR) measured AFR/DMSO, which reflected VC before induction, after CPB withdrawal, at ICU admission, and on postoperative day 1. Results: Baseline characteristics, comorbidities, and intraoperative factors were similar between groups. Postoperative organ dysfunction and inflammation were also comparable, although lactate levels were 40% higher in the VC group. POD incidence was significantly lower with VC (35.0% vs. 11.4%, p < 0.01). Logistic regression analysis confirmed that VC reduced POD risk (adjusted odds ratio 0.22, 95% CI 0.07–0.69, p < 0.01). ESR showed that postoperative AFR/DMSO levels dropped sharply but normalized by day 1 in VC-treated patients. Conclusions: This study suggests that 2 g of VC administered at ICU admission may reduce POD incidence. In the future, these findings require confirmation in randomized trials. Full article

The results of an experimental comparative study on absorptive nonlinear optical properties of deoxyribonucleic acid (DNA)–cetyltrimethylammonium chloride (CTMA) biopolymer functionalized with spirulina natural dye, as solutions in butanol, and on the same nonlinear optical properties of similar solutions with spirulina only, are presented. The spectroscopic characterisation of the investigated complexes is performed by Ultraviolet–Visible-Near-Infrared (UV-VIS-NIR) spectroscopy and Attenuated Total Reflection Fourier-transform Infrared (ATR-FTIR) spectroscopy. Their optical limiting functionality is experimentally demonstrated at the wavelength of 1550 nm (an important telecommunication wavelength) using ultrashort laser pulses (~120 fs). Important parameters that characterise the optical limiting (nonlinear absorption coefficient β, and saturation intensity, I_sat) are determined by the Intensity-scan (I-scan) method in the investigated materials. The results of our experimental investigation reveal, for the first time to the best of our knowledge, a significant absorptive nonlinear optical response of spirulina natural dye and its potential for optical limiting. The favourable effect of the DNA biopolymer on the nonlinear optical response of the investigated solutions, resulting in the enhancement of their nonlinear optical properties, is demonstrated. Thus, the investigated DNA–CTMA–spirulina liquid compound is a promising novel “green” material for passive optical limiting devices to protect sensitive optical and optoelectronic devices from high-intensity near-infrared laser beams. Also, from dye-doped DNA compounds as solutions it is possible to obtain, by different methods (e.g., spin-coating, drop casting), thin films as the base of all-optical solid-state limiting devices. Full article

This study aimed to engineer nanofibrous scaffolds that prioritize architecture, rather than relying solely on the drug, to achieve reproducible, long-acting local therapies. Cotton-wool-like fiber, three-dimensional (3D) poly(L-lactic acid)/polyethene glycol (PLLA/PEG) blend scaffolds were fabricated using solution blow spinning (SBS) as a customizable encapsulation platform for controlled antibiotic release. Morphological and wettability analyses were performed by scanning electron microscopy (SEM) and pendant-drop contact angle measurements, respectively. Fiber diameters were quantified using ImageJ. The chemical composition and thermal behavior were investigated by Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). In vitro, assays were conducted to assess the antimicrobial activity of vancomycin-loaded scaffolds against Staphylococcus aureus (disk diffusion method), as well as their cytocompatibility (Live/Dead assay in Vero cells) and hemocompatibility (ASTM F756-17 hemolysis test). All biological data were statistically analyzed using ANOVA with Tukey’s post-test, Mann–Whitney, and paired t-tests, with significance set at p ≤ 0.05. Structural optimization identified PLLA/PEG 85:15 as the most stable composition, producing homogeneous mats with high porosity and rapid wettability. Incorporation of vancomycin (10 wt.%) reduced the fiber diameter (0.23 ± 0.11 µm) compared with unloaded scaffolds (0.32 ± 0.17 µm), indicating drug–polymer interactions that modulated jet elongation. FTIR, DSC, and TGA analyses confirmed polymer miscibility and stabilization of VMC within the fibrous matrix, with no signs of degradation. Drug release exhibited a biphasic profile, with an initial burst during the first 72 h. PLLA/PEG–VMC scaffolds produced larger inhibition zones against S. aureus (18.55 mm ± 1.2 to 6.63 mm ± 0.2 at 120 h) compared with free VMC (12.91 mm ± 3.8 to 4.07 mm ± 0.6291), while blank scaffolds were inactive. Hemolysis remained within the range 2% < PLLA/PEG–VMC < 5%, indicating acceptable hemocompatibility according to ASTM standards. Although VCM-loaded PLLA/PEG scaffolds slightly reduced Vero cell viability, no statistically significant differences were observed compared with the control group. These findings demonstrate that the architecture of nanofibers presents itself as a potential platform for antimicrobial therapy with topical vancomycin in potential applications such as wound dressings or implant coatings. Full article

The surface morphology of high molecular weight poly(styrene-b-isoprene) block copolymer was analyzed after chemical modification. Poly(styrene-b-isoprene) was converted into poly(styrene-b-(ethylene-alt-propylene)) by hydrogenation and into poly(styrene-b-sulfonated isoprene) by mild sulfonation of the PI block. Obtained morphologies were examined by atomic force microscopy, analyzing the effect of sample preparation parameters such as solvent (tetrahydrofuran, toluene, and cyclohexane), casting technique (spin casting and drop casting), and annealing temperature [room temperature, 80, 100, and 120 °C]. Significant morphological and topographical changes were found depending on the different parameters. Each modification step introduces new variables that can affect the final structure and properties of the copolymer. Finding the balance between solvent choice, casting technique, and annealing conditions was a difficult task and required extensive experimentation and understanding of the principles of block copolymer self-assembly. Full article

We report the synthesis and characterization of the two enantiomeric forms of a thienyl-substituted diketopyrrolopyrrole (DPP) derivative bearing chiral alkyl chains. Thin films were prepared either by spin-coating and drop-casting and analyzed by UV–Visible absorption, electronic circular dichroism (ECD), and circularly polarized (CP) luminescence (CPL). ECD spectra confirmed the opposite chirality of the (R) and (S) isomers, while CPL measurements of the S enantiomer demonstrated solid-state chiroptical activity. Preliminary device tests showed promising optoelectronic behavior, highlighting these chiral DPP materials as potential candidates for CP organic light-emitting diodes (CP-OLEDs) applications, combining strong chiroptical response with good film quality. Full article