Search Results (1,388)

Partial migration systems offer valuable insights into how avian populations adapt to environmental shifting. While breeding ecology is widely documented, the factors governing winter site fidelity remain understudied. Using long-term ringing data from Constant Effort Ringing Stations (CESs) in central Iberia, we assessed repeated wintering-site use based on the number of wintering seasons in which individuals were recorded. Then, we examined its association with body condition and age class in the European Robin (Erithacus rubecula). Our results show that body condition significantly increases throughout the wintering period (F_1,1750 = 140.325, p < 0.001), though this effect exhibits interannual variation (F_1,844 = 5.858, p = 0.016), possibly reflecting yearly environmental fluctuations. Furthermore, adults who presented higher body condition the previous winter exhibited higher records than juveniles (F_1,598 = 8.278, p = 0.004). When accounting for unequal recapture opportunities, this association lost statistical significance, whereas age remained a significant predictor throughout the analyses (p < 0.001). These findings highlight the importance of considering age-related processes and temporal variations in body condition when assessing wintering strategies. However, the observational nature of the study and variation in sampling efforts limit our ability to distinguish true site fidelity from detection and survival. Full article

Polymer donors occupy a vital position within the active layer of organic solar cells (OSCs), and their rational molecular design and structural modulation are indispensable for the advancement of OSCs. Designing electron-withdrawing units with fused-ring skeletons is an effective strategy for constructing promising polymer donors. Herein, we report a wide-bandgap donor–acceptor (D-A)-type polymer donor, PBDQB-TF, constructed using a seven-membered fused-ring bis[1,2,5]thiadiazolo[3,4-a:3′,4′-c]dithieno[3,2-h:2′,3′-j]phenazine as the electron-withdrawing moiety. This fused aromatic skeleton exhibits strong electron-deficient character and a large conjugated plane. Benefiting from the structural merits, PBDQB-TF features a deep highest occupied molecular orbital (HOMO) energy level, broad visible-light absorption, and tunable aggregation behavior, enabling excellent spectral complementarity and energy-level alignment with classic non-fullerene acceptors BTP-eC9 and L8-BO. Photovoltaic devices fabricated from PBDQB-TF blended with either acceptor achieve promising power conversion efficiency near 10%. The PBDQB-TF:BTP-eC9 device delivers a favorable short-circuit current density of 20.03 mA cm⁻², while the PBDQB-TF:L8-BO system affords a higher open-circuit voltage of 0.964 V and a fill factor of 52.15%. Overall, this work validates the great potential of this new seven-membered, fused-ring electron-withdrawing unit and offers a reliable design principle for the development of next-generation potential polymer donor materials. Full article

Energy-efficient clustering extends the lifetime of wireless sensor networks (WSNs). Conventional protocols such as LEACH and HEED primarily address communication energy and cluster head (CH) selection rather than area coverage under random deployment. C3 considers coverage and redundancy without node coordinates; however, its virtual-ring reconfiguration is initiated by a sink or reference node. In this paper, we propose Energy-Aware Reaction–Diffusion Clustering (EARDC), a self-organizing, coordinate-free, and decentralized framework for energy-efficient area coverage in randomly deployed WSNs. EARDC determines CH formation, cluster membership, and temporary sleep states from information exchanged among one-hop neighbors. It requires neither exact node coordinates, sink-initiated reconfiguration, nor network-wide coverage information computed at the base station. A residual-energy-scaled activator–inhibitor update supports self-organized CH selection, and local membership control determines the active sensing set from selected CHs and accepted members. Other non-CH nodes sleep until the next scheduled clustering epoch. Analytical approximations for active-node density and coverage are evaluated against run-level simulation measurements to assess their accuracy and limitations. Simulations at three deployment densities characterize the tradeoff among network lifetime, coverage retention, active participation, and sensing redundancy. EARDC provides longer network lifetime and a smaller active fraction than LEACH, HEED, and WIFN. C3 provides stronger redundancy suppression. In the dense deployment, the lifetime-maximizing EARDC setting has shorter coverage retention than C3 but a longer coverage-bounded lifetime. These results show that network lifetime and sustained area coverage represent distinct performance objectives. Full article

Background/Objectives: Aquatic therapy is widely used for children with cerebral palsy (CP), but existing approaches such as the Halliwick method focus primarily on postural control and mobility with limited active resistance exercise. The Bad Ragaz Ring Method (BRRM) integrates proprioceptive neuromuscular facilitation (PNF) diagonal patterns with closed kinetic chain (CKC) exercise in the aquatic environment, yet its direct application to children with spastic CP has rarely been examined. This pilot study compared the effects of BRRM and the Halliwick method on muscle thickness, strength, and balance in verbally cooperative children with spastic CP. Methods: Twelve children with spastic CP (Gross Motor Function Classification System [GMFCS] Levels I–II, aged 5–18 years) were randomly allocated to the BRRM group (n = 6) or the Halliwick group (n = 6), stratified by GMFCS level. Both groups received 40-min sessions twice weekly for 8 weeks (16 sessions). Transversus abdominis (TrA) and tibialis anterior (TA) muscle thickness, ankle dorsiflexion (ADF) strength, one-leg stance (OLS) duration, and Timed Up and Go (TUG) performance were assessed at baseline and after 2, 4, 6, and 8 weeks. A linear mixed model was used to analyze group × time interactions. Results: Significant group × time interactions were observed for TrA thickness (p = 0.02, partial η² = 0.65), ADF strength (p < 0.01, partial η² = 0.95), and OLS duration (p = 0.02, partial η² = 0.66), with larger changes in the BRRM group. No significant between-group differences were found for TA thickness or TUG performance. Conclusions: In verbally cooperative children with spastic CP at GMFCS Levels I–II, BRRM was associated with larger changes than the Halliwick method in deep trunk muscle thickness, ankle dorsiflexion strength, and static balance. These preliminary findings support further investigation of BRRM in larger randomized controlled trials. Full article

Intersecting fissures strongly affect stress transfer and crack coalescence in rock, but their coupled effects on mechanical degradation and acoustic emission signatures remain incompletely understood. We conducted uniaxial compression tests with synchronous acoustic emission monitoring on prismatic sandstone specimens containing five intersecting-fissure configurations and on intact controls. The specimens measured 50 mm × 50 mm × 100 mm, and each prefabricated fissure was 30 mm long and 2 mm wide. The central 0–90° configuration produced the greatest degradation: its peak stress, peak strain, and elastic modulus were about 70%, 36%, and 50% lower, respectively, than those of the intact specimen. Acoustic emission ring-down counts captured the transition from early crack activation to unstable coalescence and increased sharply near macroscopic failure. Low-inclination configurations generated predominantly intermediate- and high-frequency signals, consistent with the activation of numerous small tensile cracks. Gaussian mixture model clustering of rise angle and average frequency values further showed that tensile microcracking dominated all fissured specimens, whereas the shear-crack fraction increased with fissure angle α. These findings link fissure geometry, macroscopic weakening, and acoustic emission source characteristics under uniaxial loading, providing a laboratory basis for identifying potentially hazardous intersecting-fissure configurations in underground rock engineering. Full article

Tetracycline (TC) is a widely used antibiotic that is frequently detected in rivers, lakes and wastewater. Because TC is poorly removed by conventional biological treatment, its residues can harm aquatic organisms and promote the spread of antibiotic resistance; efficient and low-cost technologies for removing TC from water are therefore needed. In this study, copper smelting slag (CSS), an abundant industrial solid waste, was converted into a catalyst composed of Fe₃O₄ particles loaded on mesoporous silica (denoted Fe₃O₄@MS) via an alkali fusion–hydrothermal method. The catalyst was used to activate peroxymonosulfate (PMS), forming the Fe₃O₄@MS/PMS treatment system for the degradation of TC in aqueous solution. The effects of the main operating parameters (catalyst dosage, PMS concentration, initial pH and reaction temperature) on TC degradation were systematically evaluated. Under the optimized conditions (catalyst 0.5 g/L, PMS 1.0 mmol/L, initial pH 6.5, 25 °C), the Fe₃O₄@MS/PMS system removed 98.70% of 50 mg/L TC within 60 min. Radical quenching experiments and electron paramagnetic resonance (EPR) analysis revealed that TC was degraded through both radical pathways (hydroxyl •OH, sulfate SO₄^•− and superoxide O₂^•− radicals) and a non-radical pathway involving singlet oxygen (¹O₂), with •OH being the dominant reactive species. Nine degradation intermediates were identified by liquid chromatography–mass spectrometry (LC-MS), based on which three degradation pathways were proposed. Toxicity estimation indicated that ring-opening and deamination reactions are the key steps for detoxification. In addition, a life cycle assessment (LCA) across five selected impact categories identified the main environmental burdens associated with catalyst production. Overall, this work demonstrates that CSS-derived Fe₃O₄@MS is an efficient, low-cost and sustainable catalyst for PMS-based antibiotic removal from water, offering a circular-economy approach that couples solid-waste valorization with clean water production. Full article

Needle roller bearings are characterized by rolling elements with relatively high length-to-diameter ratios and are widely used in mechanical systems with limited radial installation space. In gear transmission systems, periodic impact loads induced by gear meshing may be superimposed on steady radial loads, thereby altering the dynamic response of the bearing. However, the effects of the amplitude and frequency of periodic impact loading on the dynamic characteristics of needle roller bearings remain insufficiently understood. In this study, a needle roller bearing test rig capable of applying periodic impact loading was developed, and a multi-sensor measurement system was configured to measure outer-ring vibration, inner-ring motion, cage motion, and the friction torque of the bearing system. Dynamic tests were conducted under different amplitudes and frequencies of periodic impact loading. A reduction in bearing motion stability was observed under periodic impact loading, as evidenced by increased outer-ring vibration and enlarged cage motion in both the horizontal and vertical directions. As the loading amplitude increased, the RMS values of outer-ring acceleration, inner-ring displacement, and cage displacement increased, while an increase in the mean friction torque was also observed. The inner-ring trajectory expanded along the loading direction, and the whirling range of the cage trajectory increased. As the loading frequency increased, the RMS values of outer-ring acceleration, inner-ring displacement, and cage displacement increased, and the mean friction torque increased. In contrast, the whirling range of the cage trajectory decreased. These findings clarify the distinct effects of periodic impact-loading amplitude and frequency on bearing vibration, internal motion, and friction-torque characteristics and provide experimental support for the dynamic performance evaluation of needle roller bearings under impact conditions. Full article

The urban industrial spatial structure is widely recognized as a critical factor shaping public transit travel patterns. However, the relationship between variations in this spatial structure and bus origin-destination (OD) passenger flows remains insufficiently explored. To address this gap, this study proposes two quantitative indicators, namely, Regional Industrial Proximity (RIP) and Regional Industrial Scarcity (RIS), to characterize the differentiation of urban industrial spatial structures. The empirical study is conducted in the core built-up area within Beijing’s 5th Ring Road. The study area is divided into 8.3 km × 8.3 km grids, and a Proximity–Scarcity Relational Graph Convolutional Network (PS-RGCN) model is employed to predict urban bus passenger flows. The dataset primarily comprises approximately 4.21 million smart card transaction records collected over one continuous week, alongside 276,000 Points of Interest (POI) records covering 20 industrial categories. Specifically, the proposed PS-RGCN model achieves the best prediction performance among all benchmark models. The best overall performance is attained when incorporating the RIP of Scenic Spots and Historical Sites as edge relationships, yielding a coefficient of determination R² of 0.888. In comparison, the gravity model yields an R² of 0.858, and the baseline GCN model yields an R² of 0.378, indicating the superior predictive capability of the proposed model. This study verifies that industrial proximity and industrial scarcity exert complementary effects in bus OD flow prediction. Incorporating both factors synergistically into the multi-relational graph neural network framework enables more effective identification of the predictive relationship between urban functions and bus travel demand. Full article

Pyridopyrimidine is an important heterocyclic scaffold widely explored in anticancer drug discovery. Its structural similarity to purine enables effective interaction with various biological targets, mainly kinases involved in cancer progression. This manuscript presents recent developments reported between 2021 and 2026, focusing on the biological evaluation, and structure–activity relationships of pyridopyrimidine derivatives. Many of these synthesized compounds act as inhibitors of key targets such as EGFR, CDK4/6, and the PI3K/mTOR pathway, which are closely associated with tumor growth, survival, and resistance mechanisms. Other targets such as ATR and PIM are also explored. Recent studies show that structural modifications, including substitution on the core ring and hybridization with pharmacologically active moieties like triazoles and thiazolidinediones, significantly improve anticancer activity. Several derivatives have demonstrated strong antiproliferative effects against different cancer cell lines and are capable of inducing apoptosis and cell cycle arrest. In addition, molecular docking and other computational studies support their binding efficiency and help explain their mechanisms of action. There is also increasing interest in the development of dual-target or multi-target inhibitors to overcome drug resistance and enhance therapeutic effectiveness. Overall, pyridopyrimidine- and pyridopyrimidinones-based compounds continue to show great promise as potential anticancer agents. Further research combining synthetic chemistry, biological studies, and computational approaches may lead to the development of more effective and safer drugs in the future. Full article

Time-of-flight magnetic resonance angiography (TOF-MRA) is widely used for noninvasive visualization of arterial anatomy, but extracting hemodynamics like blood velocity typically requires supplementary phase-contrast scans, tagging or multi-TE images. This study proposes a novel, physics-informed computational framework to extract variable fluid velocity directly from standard TOF-MRA signal profiles. We analytically expand the approach-to-steady-state Bloch equations to include convective flow, establishing a mathematical relationship between the spatial decay of longitudinal magnetization and fluid velocity. The velocity derivation was further extended to pointwise estimation over a 1-D centerline, overcoming the limitations of constant-velocity assumptions. To validate and solve this problem, a MATLAB (R2025b) simulation framework was developed to model fluid flow in two variable-geometry flowing tube cases, i.e., continuous narrowing and focal stenosis, under synthetic scanner noise. A global inverse optimization approach utilizing Dual-Tikhonov regularization was applied to stably invert the ill-posed transit time integral, actively penalizing high-frequency numerical ringing while preserving structural curves. The computational simulations successfully recovered ground-truth point-wise velocities, tracking gradual hemodynamic accelerations and sharp stenotic jets. This theoretical framework and the example centerline TOF-MRA signal intensity provide a robust mathematical proof-of-concept that quantitative, localized functional hemodynamic metrics can be extracted from standard structural MRA imaging, establishing a foundation for advanced flow quantification without requiring additional scan time. Full article

Ring-stiffened cylindrical shells are widely used as load-bearing components in submarine pressure-hull sections. Existing underwater explosion studies have mainly emphasized incident-face denting or global failure, leaving unresolved how circumferential shock-wave diffraction and internal structural load transfer produce different response sequences and plastic-strain accumulation at the incident, side, and rear faces. A mechanism-oriented underwater explosion model test was conducted using a 44 g TNT charge at a stand-off distance of 0.50 m, and a fluid–structure interaction model was established in MSC.Dytran using the general coupling method. The model incorporated the Cowper–Symonds strain-rate effect of 16MnR steel and was validated against the Cole empirical peak pressure and measured incident-face residual deformations. The calculated free-field peak pressure was 35.50 MPa, with an error of 0.65%, while the mean relative error of the six residual-deformation measurements was 13.50%. The shell plating between adjacent ring stiffeners exhibited higher velocity and acceleration peaks than the stiffeners, indicating the local constraint imposed by the ring stiffeners. The side-face nodes showed symmetric transverse expansion, and the corresponding elements exhibited no discernible equivalent plastic strain. The rear-face center displayed a delayed axial response, and its representative element reached a final equivalent plastic strain of approximately $1.32\times {10}^{-3}$, compared with $0.40\times {10}^{-3}$ for the incident-face element. These results identify distinct circumferential response modes and show that macroscopic motion amplitude is not simply correlated with local plastic deformation. Full article

Aflatoxin B1 (AFB1) is one of the most toxic mycotoxins, widely contaminating agricultural products and posing a serious threat to food safety and human health. Enzymatic degradation is considered a promising detoxification strategy due to its high efficiency, strong specificity, and lack of secondary pollution. AKR13B3, a member of the aldo-keto reductase family, possesses intrinsic catalytic activity for AFB1 degradation; however, its low natural activity severely limits practical application. In this study, the binding mode of the AKR13B3-NADPH complex with AFB1 was first determined using AlphaFold 3.0 and AutoDock Vina. Through interaction analysis, Trp102 and Asp41 were identified as key targets for enhancing catalytic activity. Following site-directed mutagenesis screening, two mutants, D41H and D41T, with significantly improved catalytic activity were obtained, exhibiting 52.32% and 46.44% higher activity than the wild-type enzyme, respectively. Three-dimensional structural simulation revealed that D41H and D41T form stable interactions with the carbonyl group on the lactone ring of AFB1, thereby polarizing the carbonyl group and reducing the activation energy of the reaction, ultimately enhancing catalytic activity. Substrate channel analysis demonstrated that, compared with the wild-type, the D41H and D41T mutants significantly increased the bottleneck radius of the substrate channel (by 25% and 22%, respectively) and shortened the channel length (by 23% and 33%, respectively), thereby partially relieving steric hindrance and diffusion limitations and improving catalytic efficiency. In summary, this study elucidates the molecular basis by which D41H and D41T enhance the catalytic activity of AKR13B3 toward AFB1 through the dual mechanisms of external/hydrogen bond catalysis and channel remodeling, providing an important theoretical foundation for the rational design and directed engineering of AFB1-degrading enzymes. Full article

Feed efficiency classification based on residual feed intake (RFI) and residual intake and gain (RIG) is widely used to identify biologically efficient animals, yet it remains unclear whether this classification reflects consistent differences in digestive, fermentative, and metabolic processes. This study evaluated the effects of RFI and RIG classification on nutrient intake, apparent digestibility, ruminal fermentation, nitrogen metabolism, microbial protein synthesis, and gaseous emissions in confined lambs. Thirty-eight weaned Texel ewe lambs underwent a 60-day performance test using an automated feed intake system and were classified as high-efficiency, neutral, or low-efficiency based on both indices. Animals were individually housed in respirometric chambers where emissions of methane, carbon dioxide, nitrous oxide, and ammonia were assessed by cavity ring-down spectroscopy; apparent digestibility was determined from total collections of feed, orts, faeces, and urine; microbial protein synthesis was estimated from urinary purine derivatives; and ruminal short-chain fatty acid profiles were determined by gas chromatography. Feed efficiency classification did not significantly affect body weight, nutrient intake, apparent digestibility, ruminal fermentation parameters, nitrogen balance, microbial protein synthesis, or greenhouse gas emissions. Principal component analysis revealed two major biological gradients related to nutrient intake and utilisation (42.9%) and ruminal fermentation and gaseous emissions (23.3%), together explaining 66.2% of total variance, but showing no clear separation among efficiency groups. These findings indicate that the digestive, fermentative, and nitrogen metabolism variables evaluated in this study did not account for the observed variation in feed efficiency. Because the regression underlying RIG explained little additional variation (R² = 0.01), these conclusions primarily reflect feed efficiency as classified by RFI, suggesting that other physiological mechanisms may play a more important role in determining feed efficiency in confined Texel ewe lambs. Full article

Herein, we report an unexpected pseudo-multicomponent transformation discovered during attempts to selectively nitrate the pyridine core of 3-acetyl-2,4,6-trimethylpyridine (3). Despite employing standard nitration conditions, including KNO₃–H₂SO₄ and HNO₃–H₂SO₄ mixtures, electrophilic substitution of the aromatic ring did not occur. Instead, the reaction sequence promoted an in situ nitrozation, dehydration to nitrile oxide intermediates, and subsequent [3+2]-cycloaddition involving two substrate molecules. This process yielded a novel, highly functionalized furoxan derivative, precisely identified as 3,4-bis(2,4,6-trimethylnicotinoyl)-1,2,5-oxadiazole 2-oxide (5). The molecular architecture of compound 5 was established by ¹H and ¹³C NMR spectroscopy, mass spectrometry, elemental analysis, and single-crystal X-ray diffraction (XRD) analysis. To elucidate the stereochemical and electronic features governing compound 5, DFT calculations were performed at the ωB97X-D/6-311++G(d,p) level of theory. The experimental crystallographic disorder of the N-oxide oxygen atom was computationally rationalized by the thermodynamic near-degeneracy (ΔG < 0.63 kcal/mol) of two orientational isomers (5a and 5b). Furthermore, frontier molecular orbital analysis within the framework of perturbation theory accounted for the head-to-tail regioselectivity during cyclization, while wide energy gaps (ΔE = 8.13–8.27 eV) and high chemical hardness (η = 4.07–4.14 eV) underscored the kinetic stability of the heterocycle. Phenotypic and target-specific in silico profiling using PASS Online identified Matrix Metalloproteinase-9 (MMP-9) as a relevant target for potential hemorheological and cardioprotective applications. Validated molecular docking simulations across three human MMP-9 crystallographic domains (PDB: 8K5Y, 6ESM, 4XCT) demonstrated competitive binding affinities and balanced Ligand Efficiency metrics (LE = 0.26–0.29 kcal/mol/heavy atom), anchoring compound 5 within the catalytic pocket via conventional hydrogen bonds and π-mediated interactions. Finally, in vitro evaluations using a blood hyperviscosity model confirmed significant hemorheological efficacy, as compound 5 effectively prevented the rise in blood viscosity, outperforming the reference drug pentoxifylline. The convergence of computational insights and experimental functional activity establishes this novel bis(nicotinoyl)furoxan framework as a promising candidate for further hemorheological and cardioprotective applications. Full article

3,4-dihydrocoumarins and spiro compounds constitute an important class of privileged frameworks present in a wide variety of natural and synthetic molecules with diverse applications. In this study, we developed an organocatalytic methodology for the construction of complex and diverse chiral spiro-bridged 3,4-dihydrocoumarins through a Diels–Alder/Nucleophilic ring-closing cascade via trienamine activation. The reaction proceeds efficiently with different trienamine precursors and a range of coumarin-3-carboxamides, which act as both dienophile and intramolecular nucleophile species. This process affords the desired products in good yields and with a high degree of stereocontrol. Furthermore, several transformations on the newly formed spiro-piperidone ring demonstrate the synthetic utility of the obtained compounds. Full article