Search Results (4,450)

This study evaluated the effect of saliva contamination at different stages of application of an acetone-based universal adhesive on dentin bond strength. Seventy-two caries-free third molars were assigned to six groups (n = 12) according to contamination step. Specimens underwent shear bond strength testing. To determine the SBS, each bonded specimen was subjected to an SBS test in a universal testing machine (Shimadzu Autograph AGS-X; Shimadzu Corp., Kyoto, Japan) equipped for operating at a crosshead speed of 1 mm/min. Data were analyzed using one-way analysis of variance (ANOVA) followed by Tamhane’s T2 test for post hoc multiple comparisons with p ˂ 0.05 as the significance level. Saliva contamination significantly affected dentin bond strength (p < 0.001). The highest bond strength was observed in the post-polymerization contamination group with adhesive reapplication (12.32 MPa), whereas the lowest values were recorded when contamination occurred after the initial adhesive application (6.37 MPa). Overall, contamination prior to polymerization resulted in reduced bond strength, while reapplication of adhesive after polymerization improved bonding performance. Within the limitations of this in vitro study, salivary contamination adversely influences the dentin bonding effectiveness of acetone-based universal adhesives, particularly when it occurs before curing. However, adhesive reapplication following post-polymerization contamination may partially compensate for this effect. Full article

Background/Objectives: Developability assessment is a critical step in advancing antibody-based molecules toward clinical application. This evaluation typically begins during clinical candidate selection and continues throughout all modifications of the molecule during development. It is guided by the target product profile, which includes the intended administration route and regimen, formulation parameters, and process conditions encountered during manufacturing, storage, and delivery. While developability testing is well established for conventional therapeutic antibodies, strategies for assessing single-domain antibodies (sdAbs) and their conjugates remain underexplored. Here, we present a strategy to test the developability of sdAbs as a case study for two clinical candidates intended as precursors for the production of diagnostic tracers for clinical imaging. Methods: Assays were developed to evaluate chemical and thermodynamic stability, target binding affinity and capacity, and chelation efficiency (“chelatability”). Accelerated stability studies were conducted for both unconjugated sdAbs and their chelator conjugated forms following incubation at two pH conditions, at multiple time points, and after twelve freeze–thaw cycles to simulate process conditions and long-term storage. Analytical assays were applied stepwise in a hierarchical approach to minimize experimental effort and material consumption. Candidates exhibiting critical developability features were selectively addressed by assays with increasing precision. Results: A tailored panel of analytical assays optimized for low molecular weight proteins was established and applied to the two clinical candidates, identifying instability hotspots as well as potential mitigation strategies. Successful engineering of a candidate with an initially critical developability profile was achieved. Conclusions: This study demonstrates the implementation of a structured developability assessment strategy for sdAb conjugates. The approach integrates physicochemical and functional stability evaluations, supporting robust candidate selection, formulation development, and method optimization for this class of molecules. Full article

This paper details the design of a guidance architecture, in the form of a layered, finite state machine, meant to enable safe and autonomous rendezvous operations. The onboard software uses relative state parametrization based on relative orbital elements which provide significant geometrical insight into the shape of the relative orbit. The development is structured in two main steps: first, novel closed-form impulsive control schemes, derived from the Gauss Variational Equations expressed in a velocity-aligned frame, are formulated. These complement available strategies from the literature and generalize them for arbitrarily eccentric reference orbits. Secondly, the definition of the guidance layer provides the chaser spacecraft with the capability to select, schedule, and execute the proper maneuvers to complete a given rendezvous scenario, ensuring operational safety and predictability. The functionality and performance of the implemented architecture are analyzed through numerical tests in a linear propagator and a high-fidelity non-linear simulator. The results provide validation of the developed maneuvers’ strategies, as well as demonstrating how the proposed guidance architecture can be used in a straightforward fashion across different target orbit scenarios, while guaranteeing the same level of passive safety. Full article

Effective electrochemical CO₂ reduction to liquid fuels requires that the local catalytic environment facilitates the desired reactivity, yet a microscopic understanding of this environment is difficult to achieve from experiment alone. In this work, a 3D reaction-diffusion model was developed to explore the effects of electrode surface area and local geometry on the performance of a heterogeneous catalyst that performs a two-step CO₂ reduction cascade reaction to CO and then CH₃OH under aqueous conditions. Kinetic parameters for the model were inspired by experimental results using a cobalt phthalocyanine (CoPc) catalyst. Three-dimensional architectures composed of arrays of square pillars with varying dimensions and either smooth or periodically modulated surfaces were tested, revealing the extent to which geometry modulates the performance of the cascade reactions. Although structural variations modulate local concentration gradients, we find that electrochemically active surface area predominantly governs the overall cascade reaction. Moreover, the results suggest that supersaturation of CO, with concentrations up to ten-fold higher than the equilibrium solubility limit, might be critical for more efficient conversion to CH₃OH. For any given geometry, the spatially averaged ratio of [CO] to [CO₂] is dictated by the electrochemically active surface area and determines the yield of CH₃OH. For a fixed surface area, geometries that spatially confine the electrolyte yield moderate local [CO] to [CO₂] ratios within small volumes. In contrast, less confining geometries result in a broader distribution of local ratios spread over larger volumes, with both configurations yielding the same spatially averaged [CO] to [CO₂] ratio. These insights provide valuable design principles—highlighting the critical importance of surface area and possibly CO supersaturation—for engineering advanced electrode architectures that leverage intermediate trapping and CO supersaturation to enhance overall performance in tandem CO₂ reduction systems. Full article

This study systematically investigates a novel two-step approach to enhance the tribological performance of ultra-high molecular weight polyethylene (UHMWPE) by combining biaxial stretching with a subsequent hot pressing treatment. The significance of this work lies in developing a continuous, high-efficiency process that allows for decoupled control of bulk mechanical properties and surface tribological characteristics. The material’s evolution was comprehensively characterized using Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), tensile testing, and a Taber Abraser. Results show that biaxial stretching significantly enhanced the film’s bulk mechanical strength and thermal stability, creating a wider processing window for subsequent surface treatment. A subsequent hot pressing step was then applied to refine the surface characteristics, yielding an optimal wear rate of 0.002 g/1000 cycles and a kinetic coefficient of friction (µk) of 0.106. Achieving such a concurrent optimization of high wear resistance and low friction is crucial in materials processing. The study demonstrates that the synergistic effect of biaxial orientation and hot pressing-induced crystal perfection provides a powerful and previously unreported pathway to achieving a superior balance of low wear and low friction in UHMWPE. Full article

Background: It is known that the α-hydroxyphosphonates and their derivatives may have potential biological activity. Methods: Within the prominent class of α-hydroxyphosphonates, α-hydroxy-alkylphosphonates and their derivatives were prepared as new representatives in the hope of obtaining biologically active species. During our work the Pudovik reaction, acylation and phosphinoylation/phosphorylation methods were used. The new compounds were characterized by NMR and MS spectroscopy. The antiproliferative effects were tested on U266 (myeloma multiplex) and A2058 (melanoma) cells. Results: Ethyl methyl ketone–dialkyl phosphite and secondary phosphine oxide adducts were synthesized by the Pudovik reaction on the earlier analogy of acetaldehyde– and acetone adducts. The hydroxyphosphonates and hydroxyphosphine oxides were acylated and phosphinoylated/phosphorylated. Due to the steric hindrance in the case of the preparation of the acetone–and ethyl methyl ketone–diethyl phosphite adducts, a two-step procedure was elaborated that was also suitable for the thiophosphinoylation of the adducts. A part of the α-hydroxyphosphonates could be successfully methanesulfonylated. The new derivatives prepared were tested on myeloma and melanoma cells, and it was found that the antiproliferative activity is primarily driven by phosphinoylation, particularly by diphenylthiophosphinoylation. The most promising compound, the diphenylthiophosphinoylated hydroxyphosphine oxide, reduced the viability of the U266 cells to less than 20% after a treatment with 100 µM concentration in a long-term experiment. Conclusions: A subset of the synthesized α-hydroxyphosphonate derivatives exhibited cytotoxic activity, supporting further structural optimization to identify compounds with enhanced biological efficacy. Full article

This study evaluated the effect of two-step polishing procedures on the surface roughness of bulk fill restorative materials. Disk-shaped specimens (10 × 1.5 mm) were prepared from four resin composites: Filtek One Bulk Fill (3M ESPE) and Tetric PowerFill (Ivoclar Vivadent), both bulk fill nanohybrid composites; X-tra fil LC (Voco), a bulk fill microfilled composite; and Filtek Supreme (3M ESPE), a conventional nanofilled composite used as a control. Polishing was performed using D-Fine Double Diamond, Sof-Lex Diamond, and A.S.A.P. polishers. Each system was applied for 30 s with a slow-speed handpiece at 10,000 rpm under water cooling. Surface roughness (Ra) was measured before and after polishing using a profilometer, with three readings per specimen, and surface morphology was assessed by scanning electron microscopy. Data were analyzed using two-way ANOVA and Tukey’s HSD test (α = 0.05). Significant differences were observed for the interaction between composite type and polishing system (p < 0.001). The lowest Ra value was obtained for Filtek One polished with Sof-Lex Diamond, while the highest surface roughness was observed for X-tra fil LC polished with D-Fine (0.800 ± 0.072 μm). SEM analysis indicated that composites containing larger filler particles exhibited greater surface roughness. In conclusion, surface roughness after polishing was primarily material dependent, with nanofilled composites demonstrating superior polishability compared to materials with larger filler particles. Full article

The 2-Minute Step Test (2MST) is commonly scored by step count, which overlooks how the task is performed. This study tested whether a smartphone held to the thigh can be used to quantify thigh kinematics to determine 2MST outcome parameters, and whether a machine learning (ML) data analysis approach of the smartphone signal yields better agreement with motion capture (ground truth) compared to a more typical analytical data analysis approach (AA). Eighty-four healthy adults completed the 2MST while holding a smartphone against the right thigh. A thigh angular velocity ‘ground truth’ reference was obtained by simultaneous recording via motion capture (Vicon). Smartphone signals were resampled and processed using analytical (i.e., adaptive Butterworth filtering) and machine-learning data processing approaches (i.e., a stacked regression model trained to identify peak angular velocities). Step cycles and cycle duration were identical across equipment modalities and data analysis pipelines (mean 143 ± 18 cycles; 0.84 ± 0.11 s). However, the mean and variability of peak thigh angular velocity differed across the different modalities/pipelines (motion capture: 303 ± 39°·s⁻¹; AA: 280 ± 47°·s⁻¹; ML: 304 ± 37°·s⁻¹). Bland–Altman agreement, compared to the ground truth measure, showed larger bias and limits of agreement for AA (bias 25.5°·s⁻¹; −49.8–100.8) compared to ML (bias 1.0°·s⁻¹; −15.4–17.5). These findings support using a smartphone held to the thigh to assess how the 2MST is performed, including providing the number and timing of steps completed and the average and variability in thigh angular velocity across cycles. Findings also suggest that a machine learning data analysis approach provides thigh angular velocity measures that are nearly identical to motion capture techniques, whereas a typical analytical data analysis approach has errors of around 8%. Full article

Color–distance relations in the comae of 14 comets are analyzed using homogeneous broadband UBV/BVRI photometry. The sample includes several inner-Solar-System–reaching comets, including a subset from near-Earth orbits in the dynamical sense (perihelion distance $q<1.3$ au), so the results are directly relevant to the near-Earth meteoroid environment. For each comet, we combine robust color statistics, rank-correlation tests, and simple activity laws to define two empirical diagnostics: an absolute color at 1 au and a differential heliocentric color index that measures color changes with distance. The ensemble does not follow a single universal trend; instead, we identify three empirical classes. One class of comets shows significant color gradients, usually confined to blue-sensitive indices and consistent with varying gas-to-dust ratios along the orbit. A second class exhibits colors that are persistently redder than the Sun and are statistically consistent with being constant both with heliocentric distance and across perihelion. A third class of “step comets” shows discrete changes in color level between pre- and post-perihelion branches, most often in red or red–near-IR indices, with little or no monotonic color–distance correlation within each branch. Several objects therefore defy the intuitive expectation of becoming bluer as they approach the Sun, emphasizing that heliocentric color evolution is highly object-dependent and that multi-epoch color monitoring is essential for interpreting cometary coma behavior. Full article

Given growing concerns regarding data security, we develop an enhanced Advanced Encryption Standard (AES) by incorporating chaotic mapping techniques and implement it within a secure data transmission scheme, thereby strengthening protection mechanisms for both data storage and transmission processes. First, we developed a new 2D enhanced hyperchaotic map (2D-EHM) by combining classical 1D chaotic maps and conducted dynamic testing and analysis using bifurcation diagrams, phase diagrams, Lyapunov exponent graphs, and sample entropy. The results demonstrate that the 2D-EHM exhibits stronger chaotic properties compared to existing chaotic maps. Subsequently, we optimized each step of the AES algorithm by incorporating the proposed chaotic map. The enhanced AES achieves higher security at every stage of the encryption process and utilizes two different strong S-Boxes, effectively addressing the issues related to fixed points, reverse fixed points, and short periodic cycles. Based on this, we designed a secure data transmission scheme. Finally, we conducted a security analysis of the data encryption algorithm, and the results confirm the feasibility and effectiveness of our approach. Full article

The use of carbon fiber-reinforced plastic (CFRP) components has increased significantly in civilian aviation, necessitating effective maintenance and repair strategies to ensure durability and performance. While prior studies have focused on composite repair methods, such as stepped scarf patch and bolted joint repairs, these were limited to specimen and panel levels without addressing full-scale wing models. This study bridges that gap by evaluating stepped-lap repairs on a full-scale composite wing model under realistic loading conditions and exploring various repair scenarios. To reduce computational cost, two-dimensional shell elements were employed to simulate repairs, with results validated using experimental tensile test data from stepped-lap repaired specimens. Numerical models were developed for single regions and two closely located repair regions. For single-region repairs, adding up to two extra layers enhanced mechanical strength, but three extra layers increased strain, diminishing performance. For two closely located repairs, additional layers improved strength, though less effectively than single-region repairs. Square-shaped repairs exhibited higher strain due to stress concentrations at the corners, while circular repairs showed more uniform stress and strain distribution. These findings emphasize the importance of optimizing repair geometry and layer configurations using numerical simulations to ensure optimal structural performance of CFRP components. Full article

Fixed-step real-time electromagnetic-transient (EMT) simulation of large power networks typically relies on parallel partitioning, where transmission-line elements serve as step-synchronous decoupling boundaries between subsystems. In distribution and subtransmission studies, however, many line sections are electrically short and have propagation delays smaller than the simulation step. Classical Bergeron models then lose their pure one-step delay structure and require interpolation or sub-stepping, which undermines step determinism and limits the availability of decoupling boundaries, thereby constraining partition quality and scalability. This paper proposes an interpolation-free hybrid Bergeron–π boundary-line model with zero-sequence impedance modification (HB-π-ZIM). A one-step uncoupled per-phase Bergeron section enforces a delay equal to the simulation step to provide a strictly step-synchronous interface. Shunt compensation removes the artificial shunt susceptance introduced by the enforced delay, and a passive RL two-port synthesis reconstructs the residual series impedance so that, at the fundamental frequency, the terminal positive- and zero-sequence series impedances and shunt admittances match the conventional lumped-pi model. Case studies show close agreement with the lumped-pi benchmark under representative balanced and unbalanced transients, while parallel tests on a 327-node network demonstrate near-linear speedup (9.31 times on 10 cores) when HB-π-ZIM is applied only to cut-set lines. The proposed model therefore enlarges the feasible set of decoupling boundaries in short-line-dominated networks and enables scalable fixed-step real-time EMT simulation. Full article

This paper investigates the degradation of detection performance in FDA–MIMO radar systems caused by signal mismatch under constant-velocity target motion and develops a robust detection strategy to mitigate this effect. Under the effective hypothesis, a stochastic term is introduced into the received radar signal to account for mismatch uncertainty. This term is modeled as a Gaussian random variable whose covariance structure is identical to that of the noise while being scaled by an unknown robustness parameter. Based on the resulting statistical model, three robust detectors are derived using the One-Step Generalized Likelihood Ratio Test (OGLRT), the Two-Step GLRT (TGLRT), and the Gradient test. Simulation results demonstrate that all proposed detectors preserve the Constant False Alarm Rate (CFAR) property under the null hypothesis. Further performance evaluations reveal that, in the absence of signal mismatch, the OGLRT and Gradient detectors provide superior detection performance, whereas under mismatched conditions, all three detectors exhibit improved robustness. These findings provide both theoretical insight and practical guidance for the design and implementation of FDA–MIMO radar systems, contributing to the enhancement and optimization of detection performance in realistic operating environments. Full article

Background: Intellectual disability limits physical activity, affecting health and quality of life. Efficient tests to assess cardiorespiratory fitness in adapted football are essential. The Six-Minute Walk Test (6MWT) is a widely used benchmark test but can be logistically challenging. Although alternative tests such as the Sit-to-Stand Test (STST), Chester Step Test (CST), and Two-Minute Step Test in Place (2MST) have been validated in other populations, no study has examined their relationship with the 6MWT specifically in football players with intellectual disability, a population with unique physiological and cognitive characteristics. Therefore, this study reports the convergent validity between the 6MWT and these alternative field tests and describes the physiological responses to each test in football players with intellectual disability. Methods: Forty-two adult male football players with intellectual disability (mean age 27.1 ± 5.6 years) completed the 6MWT, STST, CST and 2MSPT. Physiological parameters, including heart rate, oxygen saturation (SpO₂), and systolic and diastolic blood pressure, were recorded before and after each test. Pearson’s correlation coefficients were calculated to assess relationships among tests. Results: Strong, significant correlations were found between the 6MWT and the STST (r = 0.711), CST (r = 0.724), and 2MSPT (r = 0.683) (all p < 0.001). All tests induced expected changes in heart rate, blood pressure and oxygen saturation. Conclusions: The STST, CST and 2MSPT showed strong associations with the 6MWT and may serve as practical, safe and efficient complementary tools for field-based assessment of cardiorespiratory fitness in this population. These findings apply specifically to adult male football players with intellectual disability and should not be generalized to other populations with intellectual disability. Full article

In order to prepare alkyl-functionalized reduced graphene oxide more simply, economically and environmentally, we adopt a two-step method of first reduction and then surface grafting. Graphite oxide (GtO) is first exfoliated to thermally-reduced graphene oxide (TRGO) and then, in a heat-induced solid-state reaction, converted to lauryl-functionalized TRGO (LTRGO). During the second step, lauryl radicals generated from the decomposition of lauroyl peroxide (LPO) open the epoxide rings on TRGO, covalently grafting the alkyl chains. The average water contact angle of LTRGO is 135.5°, and it disperses stably in base oil without surfactants or other additives. Four-ball test results show when the dosage of LTRGO is 75 mg/L, the average friction coefficient and wear scar diameter of the Formosa Plastics base oil (100 N) are decreased by 20.8% and 15.4%, respectively. The morphology and element analysis after ball-on-disk friction tests showed that the stable LTRGO physical friction adsorption film and metal oxide friction chemical reaction film could be formed between the friction pairs, thus reducing the friction wear. Full article