Search Results (8,123)

The Lewis acid (LA)-promoted formal [3 + 2] cycloaddition (32CA) reaction of 2-phenyl-1-tosylaziridine (2PTA) with ketone has been studied within the framework of Molecular Electron Density Theory (MEDT) at the ωB97X-D/6-311G(d,p) computational level in dichloromethane. This formal 32CA reaction proceeds through a stepwise mechanism, involving an initial BF₃ LA-promoted aziridine ring-opening process, followed by a ring-closure process to yield the 1,3-oxazolidine product. The activation enthalpy of the most favorable C2–N1 breaking bond step, ΔH^≠ = 6.42 kcal·mol⁻¹, is 20.98 kcal·mol⁻¹ lower than that of the non-catalyzed process, the aziridine ring-opening process being totally C2 regioselective and stereospecific. A topological analysis of the electron localization function (ELF) reveals that the most favorable transition state structure exhibits C2 carbocationic character; in this structure, the C2–N1 single bond has broken, while the C2–O4 single bond has not yet formed. A relative interacting atomic energy (RIAE) analysis of the aziridine ring-opening step reveals that the stabilization of the sulfonamide/LA leaving group and that of the ketone frameworks are the key factors responsible for the reduction in the activation barrier in the presence of LAs. LAs shift the mechanism of the aziridine ring-opening process from S_N2-like in the non-catalyzed reaction to S_N1-like in the LA-promoted process, which occurs with the inversion of the C2 carbon. Full article

Background/Objectives: Parkinson’s disease (PD) is a progressive neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra (SN). Because current therapeutics have limited efficacy once PD is fully developed, it is crucial to start disease-modifying interventions during the prodromal stage of PD. In the present study, we aimed to evaluate whether intranasally delivered human umbilical cord mesenchymal stem cells (hUC-MSCs) have an efficacy in the rotenone-induced prodromal PD-like phenotype mouse model. Methods: To produce the prodromal PD mouse model, C57BL/6 mice were treated with intraperitoneal (i.p.) rotenone for 1 or 2 weeks. hUC-MSCs or PBS were delivered intranasally for 1 or 2 weeks with rotenone injection. We subsequently performed behavioral assessments to evaluate motor and non-motor features, followed by pathological analyses of the mouse brains. Results: Intranasal administration of hUC-MSCs restored motor performance and protected dopaminergic neurons in the SN of mice treated with rotenone for 2 weeks. In the 1-week rotenone mice, hUC-MSCs treatment ameliorated depressive-like behaviors and attenuated olfactory dysfunction. Furthermore, intranasal hUC-MSC treatment suppressed the accumulation of protein aggregates in the brains of mice, which is associated with enhanced autophagic function, as indicated by increased LC3B and normalization of LAMP2A protein expression. Conclusions: Our data demonstrate that intranasal administration of hUC-MSCs improves non-motor symptoms at early time points and attenuates progression to nigrostriatal loss and motor deficits in the rotenone-induced PD mouse model. These findings support the potential of a non-invasive, prodromal-stage intervention to modulate early pathological progression in PD. Full article

Biological membranes are dynamic, information-rich platforms whose structural and functional properties are dictated by lipid composition rather than acting as passive barriers. Recent advances in lipidomics have revealed that variations in lipid headgroups, acyl-chain length and saturation, sn-positional architecture, and oxidative modifications profoundly influence membrane mechanics, lateral organization, and protein–lipid interactions. These features collectively regulate fundamental cellular processes, including signaling, trafficking, curvature generation, and transbilayer asymmetry. In parallel, a wide range of pathological conditions—including cancer, metabolic disorders, neurodegeneration, and inflammatory diseases—are increasingly associated with coordinated lipid remodeling that reshapes membrane material properties and electrostatic landscapes. In this review, we integrate biophysical principles with lipidomics-based evidence to elucidate how lipid chemical diversity translates into membrane-level behavior. We discuss the roles of major membrane lipid classes, the functional consequences of acyl-chain and sn-positional remodeling, and the biological significance of lipid asymmetry and lateral heterogeneity. Particular attention is given to disease-associated lipid reprogramming and extracellular vesicle lipidomes as functional extensions of cellular membranes. Finally, we examine key analytical barriers in modern lipidomics and outline strategies required to connect lipid structural information with biological function. Together, this framework highlights membrane lipid architecture as a central determinant of cellular physiology and a promising axis for mechanistic insight and translational biomarker discovery. Full article

Comprehensive design thinking is vital for architects to resolve spatial conflicts in architectural design. To address the limitations of traditional brainstorming (TB) in complex constraint scenarios, this study proposes a cognitive science-based semantic network simulation (SN) method. A controlled experiment was conducted with 60 architecture students randomly divided into SN and TB groups, tasked with solving the same rural cultural center entrance design conflict within 10 min, with eye-tracking monitoring subconscious thinking. Multi-dimensional evaluation shows TB generates more proposals, but SN outperforms TB in innovation, conflict resolution, and thought explicitness. For architects, SN provides a structured thinking tool: decompose design conflicts into nodes, establish logical connections, and generate innovative solutions through cross-domain association. The findings offer actionable methods for architectural design practice and education, helping break the “function–innovation–efficiency” trade-off. Full article

Pure SnO₂ nanofibers were synthesized via an electrospinning method and subsequently calcined at 550 °C to investigate the structure–property relationship governing H₂S gas sensing performance. X-Ray diffraction confirmed the formation of the crystalline rutile-type SnO₂. FE-SEM and TEM methods revealed a hierarchically porous morphology with fiber diameters ranging from 70 to 160 nm. BET measurements indicated a high specific surface area of 75 m²/g, consistent with the observed porous architecture. Gas sensing measurements toward H₂S revealed a pronounced response value of 25 at 200 °C with the response time of 23 s, both superior to those recorded for acetone, ethanol, and hydrogen. The enhanced sensitivity and dynamic response are attributed to the large surface area and interconnected porous network of the nanofibers, which provide the abundant active sites and facilitate efficient gas diffusion. Full article

This paper demonstrates the results of constructive technological research on the development of a catalyst with a Ni/PSi@Pt structure. This catalyst eliminates the use of gold in the structure of μ-FC electrodes. This work uses the main technological solutions for the formation of a gold-containing “core–shell” structure on the inner surface of pores. Comparative data on the results of assessing the durability of porous silicon electrodes with both Pt catalysts and composite catalysts of the Pt/In₂O₃, Pt/SnO₂, Pt/Au and Pt/Ni types are also presented. Full article

This study presents the design and performance evaluation of an advanced inorganic filler system composed of calcite (CaCO₃) and talc (Mg₃Si₄O₁₀(OH)₂), modified with a polyolefin elastomer (POE), and integrated into a high-density polyethylene (HDPE) carrier resin with process additives such as erucamide, montan wax, pe wax, and PIB. The composite was developed to improve the structural integrity and longevity of HDPE double-wall corrugated pipes. Comprehensive characterization of the filler was performed using TGA–DSC, FTIR, SEM–EDX, XRD, and XRF analyses, confirming the presence of every individual component and homogeneous dispersion in the compound. Pilot-scale extrusion pipe trials confirmed uniform filler dispersion when evaluated by SEM-EDX analysis. The filler addition increased both the density and MFI values up to 1.03 g/cm³ and 1.5 g/10 min, respectively, while test results indicated oxidation induction times (OIT) reaching up to 40 min. The developed filler-added pipes demonstrated a significantly higher ring stiffness value of 12.20 kN/m², exceeding the minimum requirement of 8 kN/m² specified for the SN8 class pipes. The POE effectively attenuated rigidity and brittleness typically induced by mineral fillers, yielding this superior stiffness while maintaining adequate ring flexibility. These findings highlight the potential of this tailored filler system to advance the production of lightweight, mechanically robust corrugated piping solutions for demanding infrastructure applications. Full article

Despite South Africa being the epicentre of HIV, some progress was made in the fight against HIV, i.e., the implementation of HIV programmes, provision of antiretroviral therapy (ART), etc. However, little is known about the association between HIV testing modalities and ART initiation. This study aimed to determine the association between HIV testing modalities and ART initiation among men who have sex with men (MSM) in selected provinces of South Africa. Following a retrospective cohort design, this study analysed programme data on 3345 MSM aged 16 years and older who were living with HIV and eligible for ART initiation. Logistic regression assessed the association between HIV testing modalities and ART initiation, controlling for age group, location, and the COVID-19 period. All analyses were done using SPSS version 30. Significance was set at p < 0.05. Participants who tested for HIV using the social network strategy (SNS) (98.6%) or index testing (96.3%) showed the highest proportions of ART initiation. Logistic regression showed that MSM who tested for HIV using the SNS had over 12 times higher odds of initiating ART (aOR = 12.166; 95% CI: 7.617–19.430; p < 0.001), compared to those who used a rapid test. A significant association was observed between HIV testing modalities and ART initiation, with SNS and index testing demonstrating higher odds of ART initiation. Full article

Drought stress critically constrains plant development and morphogenesis, representing a substantial challenge to crop production systems. Dehydrins (DHNs), belonging to the late embryogenesis abundant (LEA) protein superfamily, play crucial roles in plant adaptation to environmental stress conditions. Nevertheless, the capacity of Suaeda salsa SsDHN protein to confer drought resistance has not been adequately investigated. In the present study, transgenic tobacco lines with constitutive SsDHN expression (SsDHN-OE) were employed to examine its influence on seedling development under water-limited conditions. Results indicated that constitutive SsDHN expression enhanced biomass accumulation, foliar expansion, root elongation, and root surface dimensions in water-stressed seedlings. Moreover, transformed lines demonstrated elevated proline (Pro) accumulation and abscisic acid (ABA) content, augmented antioxidant enzyme activity, and intensified stomatal regulation under stress conditions. Conversely, photoinhibition intensity, chloroplast structural degradation, malondialdehyde (MDA) accumulation, electrolyte leakage, hydrogen peroxide (H₂O₂), and superoxide radical (O₂⁻) concentrations were diminished. Furthermore, transcript abundance of stress-responsive genes—encompassing NtNCED3, NtSnRK2.2, NtRD26, NtLEA5, NtPOD, NtSOD, NtCAT, and NtAPX1—was markedly increased in SsDHN-OE lines experiencing drought stress. Taken together, these findings establish that SsDHN functions as a positive regulator of drought resilience in plants. Full article

Very-high-cycle fretting fatigue (VHCFF) behavior at elevated temperatures is critical for the safety and longevity of aerospace components. This study investigates the VHCFF mechanisms of laser-clad IN718/20%WC composite coatings at 650 °C. Fatigue tests were conducted to generate S-N data, and the resulting wear and fracture morphologies were characterized. Crack initiation was found to preferentially occur in grains exhibiting higher Schmid factors, lower elastic moduli, and larger equivalent sizes. To simulate fretting fatigue, a crystal plasticity finite element model (CPFEM) incorporating the actual microstructure was developed. An improved fatigue indicator parameter (FIP) was proposed, which integrates multiple physically significant factors including plastic strain, dislocation density, elastic modulus, and grain size. Life predictions based on a critical FIP value demonstrated high accuracy, with 97.6% of the results falling within a ±3.5 scatter band of the experimental data, confirming the model’s effectiveness in predicting crack initiation life. Full article

This work aims to enhance the stability of the Mg/Al₃Y interface through first-principles investigations of low-cost dopants. Density functional theory calculations were employed to systematically examine the bulk properties of Mg and Al₃Y, as well as the structural stability, electronic characteristics, and alloying element effects at the Mg(0001)/Al₃Y(0001) interface. The calculated lattice parameters, elastic moduli, and phonon spectra demonstrate that both Mg and Al₃Y are dynamically stable. Owing to the similar hexagonal symmetry and a small lattice mismatch (~1.27%), a low-strain semi-coherent Mg(0001)/(2 × 2)Al₃Y(0001) interface can be constructed. Three representative interfacial stacking configurations (OT, MT, and HCP) were examined, among which the MT configuration exhibits significantly higher work of adhesion, indicating superior interfacial stability. Differential charge density and density of states analyses reveal pronounced charge transfer from Mg to Al/Y atoms and strong orbital hybridization, particularly involving Y-d states, which underpins the enhanced interfacial bonding. Furthermore, the segregation behavior and adhesion enhancement effects of typical alloying elements (Si, Ca, Ti, Mn, Cu, Zn, Zr, and Sn) were systematically evaluated. The results show that Mg-side interfacial sites, especially Mg₂ and Mg₃, are thermodynamically favored for segregation, with Zr and Ti exhibiting the strongest segregation tendency and the most significant improvement in interfacial adhesion. These findings provide fundamental insights into interfacial strengthening mechanisms and offer guidance for the alloy design of high-performance Mg-based composites. Full article

Background: Burn wound repair is driven by oxidative balance and keratinocyte regeneration. Polyphenol-rich botanicals are considered promising due to combined antioxidant and pro-regenerative properties. This study compares four ethnopharmacologically relevant species—Boswellia serrata (BS), Sambucus nigra (SN), Ocimum basilicum (OB), and Galium verum (GV)—to determine how their polyphenolic class profiles relate to in vitro regenerative activity. Methods: Ethanolic (E—99.5%) and hydroalcoholic (H—70%) extracts were profiled by LC–MS, total polyphenol content (TPC), and DPPH assays. Biological effects were assessed in HaCaT keratinocytes using Alamar Blue (24/48 h) and scratch wound closure (24 h), and results were correlated with chemical profiles. Results: The H extract of OB (OB-H) and of GV (GV-H) had the highest TPC (62.6 and 63.9 mg GAE/g) and lowest DPPH IC₅₀ (18.7 and 17.1 μg/mL), aligning with the strongest biological responses—HaCaT viability up to 169.1% and wound closure up to 414%. SN extracts, dominated by rutin, promoted moderate migration with preserved viability, whereas BS produced modest viability gains. Conclusions: Polyphenolic composition—particularly the dominance of phenolic acids—correlates strongly with in vitro regenerative responses in HaCaT keratinocytes. O. basilicum and G. verum hydroalcoholic extracts displayed the most favorable profiles. Full article

To address the issues of parameter setting, reliance on human experience, and the limitations of traditional model-driven control methods in handling complex nonlinear dynamics in the tin smelting industrial process, this paper proposes a data-driven control approach based on improved deep reinforcement learning (RL). Aiming to reduce the tin entrainment rate in smelting slag and CO emissions in exhaust gas, we construct a data-driven environment model with an 8-dimensional state space (including furnace temperature, pressure, gas composition, etc.) and an 8-dimensional action space (including lance parameters such as material flow, oxygen content, backpressure, etc.). We innovatively design a Dual-Action Discriminative Deep Deterministic Policy Gradient (DADDPG) algorithm. This method employs an online Actor network to simultaneously generate deterministic and exploratory random actions, with the Critic network selecting high-value actions for execution, consistently enhancing policy exploration efficiency. Combined with a composite reward function (integrating real-time Sn/CO content, their variations, and continuous penalty mechanisms for safety constraints), the approach achieves multi-objective dynamic optimization. Experiments based on real tin smelting production line data validate the environment model, with results demonstrating that the tin content in slag is reduced to between 3.5% and 4%, and CO content in exhaust gas is decreased to between 2000 and 2700 ppm. Full article

At the Ity gold deposit (Ivory Coast), carbonate-buffered tropical weathering fundamentally controlled the redistribution and enrichment of gold and associated metals within the Flotouo weathering profile. Primary mineralisation formed through skarn development at quartz diorite contacts, followed by mesothermal stages around 2 Ga, establishing the initial Au and trace-metal endowment. Hypogene processes alone, however, cannot explain the present distribution and concentration of Au, Cu, Mo, Bi, Sn, and W. Cenozoïc tropical weathering profoundly transformed the ores through coupled sulphide oxidation and carbonate dissolution. Oxidation of sulfides releases metals into circulating fluids. At the same time, dissolution of marble lenses buffered the pH towards near-neutral conditions, limiting long-distance metal transport and favouring local residual enrichment and secondary immobilisation. These processes, together with leaching of Ca, S, and Si, increased porosity and permeability, promoted fluid flow through karstic voids and collapse breccias. A lateritic blanket extends above the saprolitised hypogene ores. A systematic vertical mineralogical zonation developed across the profile, with goethite-dominated laterite at the top, kaolinite-rich saprolite in the middle, and smectite-bearing horizons at depth. This study highlights the key role of pH-buffered tropical lateritisation in upgrading pre-existing skarn-related mineralisation and producing atypical trace-metal enrichments in Birimian gold systems, providing a mechanistic framework relevant for regional exploration models. Full article

Topological semimetals with nontrivial band structures host a variety of unconventional transport phenomena and have attracted significant attention in condensed matter physics. SnTaS₂, a recently proposed topological nodal-line superconductor with a centrosymmetric layered structure, provides an ideal platform to explore the interplay between topology and electronic transport. Here, we report a comprehensive study of the normal-state magnetotransport and magneto-thermoelectric properties of SnTaS₂ single crystals. We observed large magnetoresistance and nonlinear Hall resistivity at low temperatures, which can be well described by a two-band model, indicating the coexistence of electron and hole carriers. The Seebeck and Nernst coefficients were found to exhibit pronounced and nonmonotonic magnetic field dependences at low temperatures, consistent with multiband transport behavior. Moreover, clear quantum oscillations with a single frequency are detected in both electrical and thermoelectric measurements. Analysis of the oscillations reveals a small effective mass and a nontrivial Berry phase, suggesting that the corresponding Fermi surface arises from a topologically nontrivial band. These findings shed light on the normal-state electronic structure of SnTaS₂ and highlight the important role of topological bands in shaping its transport properties. Full article