Search Results (426)

Prostate-specific antigen (PSA) is a key biomarker for the early detection of prostate cancer recurrence following surgical treatment. In this study, we present a PSA-responsive, aptamer-based switchable aggregate system, named AS2-US-AuNP-Aggregate, composed of ultrasmall gold nanoparticles (US-AuNPs) linked by (partially) pairing oligomers that selectively disassemble in the presence of PSA. The system was optimised also using a previously developed in silico routine and is designed for enhanced detection capabilities and for supporting in vivo applicability. We measured the sizes of the nanosystems by dynamic light scattering (DLS) and their extinction spectra, also in the presence of PSA in simple buffers, in the presence of DNaseI, and under blood-mimicking conditions (filtered plasma), obtaining a response down to 10 fM PSA in buffers and to 1 pM in filtered plasma. Our findings highlight the potential of aptamer-based nanoparticle aggregates as a basis for user-friendly diagnostic tools. Additionally, we discuss key optimisation strategies to further advance their development for in vivo diagnostic applications. Full article

This study introduces a novel imaging technology designed to address the critical challenges of high integration, wide field of view (FOV), and high-resolution detection in optoelectronic systems. The proposed approach leverages ultra-small pixels and a unique “single-eye + compound-eye” architecture, combining a concentric spherical lens for wide-FOV light collection with a distributed camera array for segmented imaging and stitching of the Petzval image plane. This design enables high-resolution imaging across a large area while maintaining compact system dimensions. The ultra-small-pixel large-format detector excels in capturing fine details, and by applying linear system theory, the technology achieves significant reductions in system size and complexity without compromising performance. Experimental validation shows that the imaging system achieves a modulation transfer function near the diffraction limit at 500 lp/mm, with a root-mean-square spot size consistently below 1 $\mathrm{\mu }$m. Additionally, the system delivers an angular resolution of 25 $\mathrm{\mu }$rad and distortion-free imaging over a ${61.5}^{\circ }\times {55}^{\circ }$ FOV. Full article

Background: Left ventricular (LV) mechanics assessed by speckle-tracking echocardiography provides sensitive markers of cardiac adaptation to exercise. Different training modalities—endurance, high-intensity interval training (HIIT), and acute exercise tests—impose distinct hemodynamic loads, yet their comparative effects on LV deformation remain unclear. Importantly, acute and chronic endurance exposures may elicit divergent myocardial responses that must be interpreted separately. Methods: A systematic search of PubMed, Scopus, and EMBASE (through September 2025) identified studies evaluating LV mechanics in response to endurance, HIIT, or acute exercise among healthy or recreationally active individuals. Echocardiographic parameters of strain and torsion were extracted, and methodological quality was appraised using the NIH Quality Assessment Tool. Results: Twenty-three studies (859 participants) met inclusion criteria. Acute prolonged endurance exercise—particularly marathon and ultra-endurance events—was associated with transient, fully reversible reductions in global longitudinal, circumferential, and radial strain and torsion, despite preserved ejection fraction, reflecting short-term myocardial fatigue rather than maladaptive remodeling. In contrast, chronic endurance training maintained or improved LV mechanics without evidence of dysfunction, while HIIT interventions consistently enhanced LV systolic strain and rotational indices across diverse age groups and sexes, reflecting improved contractile efficiency and physiological remodeling. Acute exercise produced heterogeneous, load-dependent strain responses, with isometric stress increasing regional strain and maximal exertion inducing temporary global reductions. Between-study heterogeneity was moderate, methodological quality generally good, and small-study effects varied by modality, being most evident in endurance studies, borderline for HIIT, and limited for acute tests due to sample size. Conclusions: Acute endurance exercise produces transient, reversible LV deformation changes, whereas chronic endurance training preserves mechanical efficiency. HIIT reliably enhances systolic strain and torsional mechanics, and acute exercise elicits variable but physiologically meaningful responses. These findings clarify that transient post-race strain reductions reflect physiological fatigue, not chronic maladaptation, and underscore the modality-specific nature of myocardial adaptation to exercise. Full article

Critically sized bone defects remain a global health and economic burden, and biomaterials associated with stem cell therapy have been widely applied as a significant strategy for bone regeneration. Due to limitations related to cell survivability, immune rejection, and transplantation at the defective bone site, the improved therapeutic outcomes of stem cells are achieved through paracrine actions, which involve the secretion of extracellular vesicles (EVs) and/or other factors. Ultra-small, nano-sized exosomes (Exos) of endosomal origin have demonstrated promising potential for bone regeneration through partially revealed intercellular communication. However, the real-time feasibility before clinical trials remains unknown. The current report aims to provide an overview of the various stem cell-derived exosomes in treating bone and cartilage defects, including osteoarthritis (OA) and osteochondral defect (OCD), and optimize the yield of Exos with enhanced tissue engineering potentials. Additionally, the encapsulation of Exos with various bioactive molecules to enhance therapeutic efficacy, their functionalization with biocompatible scaffolds to promote sustained release in the defective cellular microenvironment, and the molecular functions of Exos were investigated. Full article

This research presents an ultra-wideband antenna array for the non-invasive early detection of brain tumors. The primary objective of this work is to evaluate the detection capabilities of a proposed Vivaldi antenna array system for identifying small and multiple brain tumors under various simulated biological conditions. The core of the system is a Vivaldi-type antenna operating from 2.4 to 17.7 GHz, configured in both two- and four-antenna arrays. A high-fidelity, seven-layer phantom model was developed to replicate brain tissue, with each layer assigned specific electromagnetic properties (relative permittivity, tangential loss) and physical thickness. The study rigorously analyzes the system’s performance in detecting tumors across diverse scenarios, including variations in phantom complexity, tumor size, permittivity, and the number of present tumors. Using the Delay and Sum algorithm for image reconstruction, the results demonstrate the system’s feasibility in detecting tumors as small as 0.625 mm in diameter. This underscores the significant potential of the proposed design as a powerful tool for non-invasive medical diagnostics. Full article

Nanoparticles (NPs) have significantly changed the field of drug delivery, offering control over pharmacokinetics, biodistribution, and targeted therapy. Among these, ultrasmall nanoparticles (USNPs) with sizes of approximately 5–15 nm have garnered significant interest due to their unique physicochemical properties, including enhanced cellular uptake, deeper tissue penetration, and prolonged systemic circulation. This review explores the fundamental principles governing sub-15 nm nanoparticles, their classification, and their distinctive advantages in pharmaceutical applications. Various types of nanoparticles, including polymeric, lipid-based, metallic, and carbon-based nanosystems, are examined in the context of drug delivery in cancer therapy. We detail how sub-15 nm polymeric nanoparticles (PNPs) are emerging as transformative drug delivery platforms for cancer therapy. The impact of nanoparticle size, surface modifications, and biocompatibility on therapeutic performance is critically analyzed. Furthermore, we discuss emerging applications of these ultrasmall nanoparticles in cancer therapy, neurological disorders, vaccine delivery, and imaging. Despite their promise, key challenges such as stability, aggregation, toxicity, and regulatory concerns remain significant hurdles for clinical translation. This review provides insights into the potential of 5–15 nm nanoparticles to reshape modern drug delivery and highlights future directions for research and development in this rapidly evolving field. Full article

Localized ¹H magnetic resonance spectroscopy (MRS) is a powerful tool in pre-clinical and clinical neurological research, offering non-invasive insight into neurochemical composition in localized brain regions. Zebrafish (Danio rerio) are increasingly being utilized as models in neurological disorder research, providing valuable insights into disease mechanisms. However, the small size of the zebrafish brain and limited MRS sensitivity at low magnetic fields hinder comprehensive neurochemical analysis of localized brain regions. Here, we investigate the potential of ultra-high-field (UHF) MR systems, particularly 28.2 T, for this purpose. This present study pioneers the application of localized ¹H spectroscopy in zebrafish brain at 28.2 T. Point resolved spectroscopy (PRESS) sequence parameters were optimized to reduce the impact of chemical shift displacement error and to enable molecular level information from distinct brain regions. Optimized parameters included gradient strength, excitation frequency, echo time, and voxel volume specifically targeting the 0–4.5 ppm chemical shift regions. Exceptionally high-resolution cerebral metabolite spectra were successfully acquired from localized regions of the zebrafish brain in voxels as small as 125 nL, allowing for the identification and quantification of major brain metabolites with remarkable spectral clarity, including lactate, myo-inositol, creatine, alanine, glutamate, glutamine, choline (phosphocholine + glycerol-phospho-choline), taurine, aspartate, N-acetylaspartyl-glutamate (NAAG), N-acetylaspartate (NAA), and γ-aminobutyric acid (GABA). The unprecedented spatial resolution achieved in a small model organism enabled detailed comparisons of the neurochemical composition across distinct zebrafish brain regions, including the forebrain, midbrain, and hindbrain. This level of precision opens exciting new opportunities to investigate how specific diseases in zebrafish models influence the neurochemical composition of specific brain areas. Full article

Hydrogels are three-dimensional polymeric networks capable of retaining large amounts of water. Polyvinyl alcohol (PVA)-based hydrogels exhibit autonomous self-healing through reversible physical interactions within the hydrogel matrix, including hydrogen bonding, crystallite formation, and dynamic crosslinking. However, their long self-healing times and low strength limit practical application. Herein, we propose an effective strategy to simultaneously achieve excellent self-repairing and high mechanical strength. The tensile strength of uncut PVA hydrogel was 1.21 MPa; after cutting and rejoining for 12 h at room temperature (RT), it recovered 94% of the original uncut strength. To accelerate self-healing, hydrogels were treated at 40, 50, and 60 °C for 20, 40, and 60 min. Under optimal conditions (60 °C for 60 min), 96% recovery was achieved. Mechanical properties were further improved by silica (Si) nanoparticles of various sizes (~12, ~85, and ~200 nm). Si-loaded hydrogels, particularly ~12 nm, demonstrated increased mechanical properties, reaching a tensile strength of 1.45 MPa and a self-healing recovery of 95% of the uncut hydrogel strength. Ultra-small (~12 nm) Si nanoparticles enhanced the overall mechanical properties by acting as an efficient nucleating agent and did not hinder the existing self-healing mechanism. The developed strategy will pave the way for novel techniques in hydrogel research and will advance applications such as soft robotics and wound dressing. Full article

We present a compact hybrid imaging system operating in the 3–5 μm spectral band that combines refractive optics with a dispersion-engineered metasurface to overcome the longstanding trade-off between wide field of view (FOV), system size, and thermal stability. The system achieves an ultra-wide 178° FOV within a total track length of only 28.25 mm, employing just three refractive lenses and one metasurface. Through co-optimization of material selection and system architecture, it maintains the modulation transfer function (MTF) exceeding 0.54 at 33 lp/mm and the geometric (GEO) radius below 15 μm across an extended operational temperature range from –40 °C to 60 °C. The metasurface is designed using a propagation phase approach with cylindrical unit cells to ensure polarization-insensitive behavior, and its broadband dispersion-free phase profile is optimized via a particle swarm algorithm. The results indicate that phase-matching errors remain small at all wavelengths, with a mean value of 0.11068. This design provides an environmentally resilient solution for lightweight applications, including automotive infrared night vision and unmanned aerial vehicle remote sensing. Full article

Mesoporous silica nanoparticles have been synthesized through sol–gel synthesis in basic conditions. Gemini surfactants having urea in the headgroups were used as pore-forming agents. The effect of the spacer length of the surfactant on the particle morphology was studied on the sub-micrometer and nanometer scales using nitrogen porosimetry, small-angle X-ray scattering (SAXS), ultra-small-angle neutron scattering, and scanning and transmission electron microscopy (SEM, TEM). Depending on the spacer, spherical and/or cylindrical nanoparticles formed in different proportions, as revealed by statistical analysis of SEM micrographs. All prepared materials showed the hexagonal pore structure characteristic of the MCM-41 molecular sieves, with the exception of the sample prepared using the gemini surfactant with the shortest spacer length. The influence of the spacer length on the lattice parameter of the pore network, as well as the average size of the ordered domains, has been assessed by SAXS and TEM. Detailed analysis of the TEM images revealed a spread of the lattice parameter in a range of 10–20%. The broadening of the diffraction peaks was shown to be due to the combination of the effects of the finite domain size and the variance of the lattice parameter across the crystalline domains. The structural differences between the silica gels synthesized with the different surfactants were related to the variation of the micelle morphologies, reported in previous light scattering and small-angle scattering experiments. No connection could be revealed between the micelle shape and size and the pore sizes, showing that surfactants with a broad range of spacer lengths can equally well be used for the preparation of MCM-41 materials. Full article

This paper introduces a power-driven systems engineering methodology for the early-phase design of highly miniaturized satellites: PlanarSats. We derive an analytical framework linking power requirements, contingency policies, solar-cell performance, and subsystem integration to determine the absolute minimum satellite size. Through idealized and detailed case studies, we explore the trade-offs inherent in subsystem selection and integration constraints. Sensitivity analysis identifies critical factors affecting minimum area and operational envelopes. Our framework provides a clear tool for balancing functionality, reliability, and physical limits in next-generation ultra-small satellite missions. Full article

Molecular quantum-dot cellular automata (QCA) are attracting much attention as an alternative that can improve the problems of digital circuit design technology represented by existing CMOS technology. In particular, they are well suited to the upcoming nanoquantum environment era with their small size, fast switching speed, and low power consumption. In this study, we propose a 5 × 5 × 1 ultra-slim vertical panel type multi-layer 2-to-1 multiplexer (Mux) using molecular QCA, departing from conventional multi-layer formats, and show its expansion to 4-to-1 Mux and application to vertical panel type D-latch and RAM cells. In addition, the polarization phenomenon of cells is physically proven using the potential energy, distance among electrons, and the relative positions of cells, and the secure RAM design takes noise elimination and polarization of the output signal into consideration. The circuits are simulated in terms of operation and performance using QCADesigner 2.0.3 and QCADesignerE, and the proposed multi-layer 2-to-1 Mux shows a significant improvement of at least 1473% and 277% in two representative standard design costs compared to the state-of-the-art multi-layer Muxes. Full article

Ultra-deep tight sandstone gas reservoirs are key targets for natural gas exploration, yet their pore structures under high temperature, pressure, and stress greatly affect gas occurrence and flow. This study investigates representative reservoirs in the Kelasu structural belt, Tarim Basin. Porosity–permeability were measured under in situ conditions, and multi-scale pore structures were analyzed using thin sections, a SEM, mercury intrusion, and nitrogen adsorption. The results show that (1) the median permeability of cores at an ambient temperature and a confining stress of 3 MPa is 13.33–29.63 times that under the in situ temperature and pressure conditions. When the core permeability is lower than 0.1 mD, the stress sensitivity effect is significantly enhanced; (2) nanopores and micron-fractures are well developed yet exhibit poor connectivity. The majority of a core’s porosity is derived from the intergranular pores in clay minerals; (3) the volume of nano-sized pores within the 100 nm diameter range is mainly composed of mesopores, with an average proportion of 73.37%, while the average proportions of macropores and micropores are 22.29% and 4.34%, respectively; (4) full-scale pore sizes show bimodal peaks at 100–1000 nm and >100 μm, which are poorly connected; (5) the pore structure exhibits distinct fractal characteristics. The fractal dimension D_f1 (2.65 on average) corresponds to the larger pore diameters of the primary intergranular pores, residual intergranular pores, and intragranular dissolution pores. The fractal dimension D_f2 (2.10 on average) corresponds to the grain margin fractures, micron-fractures and partial throats. The pore types corresponding to the fractal dimensions D_f3 (2.36 on average) and D_f4 (2.58 on average) are mainly intercrystalline pores of clay minerals and a small number of intraparticle dissolution pores. These findings clarify the pore structure of ultra-deep tight sandstones and provide insights into their gas occurrence and flow mechanisms. Full article

Metallic nanoclusters (NCs), composed of a few to a hundred atoms, occupy a unique space between molecules and nanoparticles, exhibiting discrete electronic states, strong photoluminescence, and size-dependent catalytic activity. Their ultrasmall cores (<3 nm) and ligand-controlled surfaces confer tunable optical, electronic, and catalytic properties, making them attractive for diverse applications. In recent years, significant progress has been made toward developing faster, more reproducible, and scalable synthesis routes beyond classical wet-chemical reduction. Emerging strategies such as microwave-, photochemical-, sonochemical-, and catalytically assisted syntheses, together with smart, automation-driven platforms, have improved efficiency, structural control, and environmental compatibility. These advances have accelerated the deployment of NCs in imaging, sensing, and catalysis. Near-infrared emitting NCs enable deep-tissue, high-contrast fluorescence imaging, while theranostic platforms combine diagnostic precision with photothermal or photodynamic therapy, gene delivery, and anti-inflammatory treatment. NC-based sensors allow ultrasensitive detection of ions, small molecules, and pathogens, and atomically precise NCs have enabled efficient CO₂ reduction, water splitting, and nitrogen fixation. Therefore, in this review, we highlight studies reported in the past five years on the synthesis and applications of metallic NCs, linking emerging methodologies to their functional potential in nanotechnology. Full article

To address the challenge of efficiently identifying and providing early warnings for typical structural damages in small and medium-sized bridges during long-term service, this paper proposes an intelligent monitoring and recognition method based on ultra-weak fiber Bragg grating (UWFBG) array sensing. By deploying UWFBG strain-sensing cables across the bridge, the system enables continuous acquisition and spatial analysis of multi-point strain data. Based on this, a series of experimental scenarios simulating typical structural damages—such as single-slab loading, eccentric loading, and bearing detachment—are designed to systematically analyze strain evolution patterns before and after damage occurrence. While strain distribution maps allow for visual identification of some typical damages, the approach remains limited by reliance on manual interpretation, low recognition efficiency, and weak detection capability for atypical damages. To overcome these limitations, machine learning algorithms are further introduced to extract features from strain data and perform pattern recognition, enabling the construction of an automated damage identification model. This approach enhances both the accuracy and robustness of damage recognition, achieving rapid classification and intelligent diagnosis of structural conditions. The results demonstrate that the integration of the monitoring system with intelligent recognition algorithms effectively distinguishes different types of damage and shows promising potential for engineering applications. Full article