Search Results (114)

Precast bridge columns offer efficiency and environmental benefits, yet complex mountainous terrain and limited workspace severely restrict the transportation of large segments. To address this challenge and the limited ductility of traditional connections, this study proposes a multi-segment precast bridge column with hybrid connections (PSC-GSPT) utilizing grouted sleeves and unbonded prestressing tendons. Quasi-static tests and OpenSees simulations compared a three-segment PSC-GSPT specimen with a cast-in-place (CIP) column. Results demonstrate that the hybrid system shifts the plastic hinge above the sleeves due to their high stiffness, ensuring controlled damage. Compared to the CIP specimen, the PSC-GSPT increased peak load by 30.2% and ductility by 20.7%, while exhibiting excellent self-centering capability and 27% higher cumulative energy dissipation. Numerical parametric analysis indicates that a central tendon configuration delays yielding, boosting ductility by over 15% versus perimeter layouts, and an initial prestress level of 30% is recommended to optimize both self-centering and ductility. This study provides a theoretical basis for applying high-performance precast piers in transportation-restricted environments. Full article

To address the limitation of 2D methods in inferring absolute scrap dimensions from images, we propose Scrap-SAM-CLIP (SSC), a vision-language model integrating the segment anything model (SAM) and contrastive language-image pre-training in Chinese (CN-CLIP). The model enables identification of canonical scrap shapes, establishing a foundational framework for subsequent 3D reconstruction and dimensional extraction within the 3D recognition pipeline. Individual modules of SSC are fine-tuned on the self-constructed scrap dataset. For segmentation, the combined box-and-point prompt yields optimal performance among various prompting strategies. MobileSAM and SAM-HQ-Tiny serve as effective lightweight alternatives for edge deployment. Fine-tuning the SAM decoder significantly enhances robustness under noisy prompts, improving accuracy by at least 5.55% with a five-positive-points prompt and up to 15.00% with a five-positive-points-and-five-negative-points prompt. In classification, SSC achieves 95.3% accuracy, outperforming Swin Transformer V2_base by 2.9%, with t-SNE visualizations confirming superior feature learning capability. The performance advantages of SSC stem from its modular assembly strategy, enabling component-specific optimization through subtask decoupling and enhancing system interpretability. This work refines the scrap 3D identification pipeline and demonstrates the efficacy of adapted foundation models in industrial vision systems. Full article

Background: Amyloidogenic proteins, a heterogenous group of proteins characterized by their ability to form amyloid fibrils, lead to pathological conditions when they undergo abnormal folding and self-assembly. Missense single-nucleotide polymorphisms (msSNPs) may occur in their sequence, disrupting the normal structure and function of these proteins, pushing them towards amyloidogenesis. Methods: A comprehensive dataset of amyloidogenic proteins was created and their msSNPs were collected and mapped on their amino acid sequence. The chi squared test, logistic regression and the bootstrap method were used to ascertain the statistical significance of the results. Results: The distribution of pathogenic and benign msSNPs highlighted the predicted amyloidogenic segments as hotspots for pathogenic msSNPs. Analysis of the change in residue properties and pathogenicity status revealed that the substitution of negatively charged residues by any other type of residue tends to be pathogenic. Furthermore, certain substitutions were found to be more likely pathogenic than average. Additionally, a case study of APP, a key protein in Alzheimer’s disease, is used as an example. Conclusions: This study will hopefully showcase the importance of amyloidogenic protein msSNPs as well as spark an interest in research of the mechanisms that lead to the formation of amyloid deposits under the scope of pathogenic msSNPs. Full article

Large-scale computer simulations were employed to investigate the conformational response of the spike protein components S1 and S2 using a coarse-grained model. Temperature was systematically varied to assess the balance between stabilizing residue–residue interactions and thermal fluctuations. The resulting contact profiles reveal distinct segmental reorganization and self-assembly behaviors between S1 and S2. At lower, thermoresponsive temperatures, pronounced segmental globularization occurs in the N-terminal domain (NTD; M153–K202) and receptor-binding domain (RBD; E406–E471) of S1, whereas S2 exhibits alternating regions of high and low contact density. Increasing temperature reduces this segmental globularization, leaving only minor persistence at elevated temperatures. The temperature dependence of the radius of gyration (R_g) further demonstrates the contrasting thermal behaviors of S1 and S2. For S1, R_g increases continuously and monotonically with temperature, reaching a steady-state value approximately 50% higher than that at low temperature. In contrast, S2 displays a non-monotonic response: R_g initially rises to a maximum nearly sevenfold higher than its low-temperature value, then decreases with further temperature increase. Scaling analysis of the structure factor reveals that the globularity of S1 diminishes significantly upon heating, while S2 becomes modestly more compact yet retains its predominantly fibrous character. Full article

This study examined a novel ethoxy-segment-regulated hydrophobic associative amphiphilic copolymer, P(AA-AAEO_n), and systematically evaluated its solution self-assembly behavior and enhanced oil recovery (EOR) performance. The influence of ethylene oxide (EO) chain length and polymer concentration on particle size distribution and aggregation morphology was analyzed using dynamic light scattering (DLS). The results revealed a concentration-dependent transition from intramolecular to intermolecular association, accompanied by a characteristic decrease followed by an increase in hydrodynamic diameter. At a fixed AA:AAEO_n molar ratio (400:1), increasing EO segment length increased aggregate size and improved colloidal stability. Viscometric analysis showed that longer EO chains markedly increased molecular chain flexibility and solution viscosity. Interfacial tension measurements demonstrated superior interfacial activity of P(AA-AAEO_n) compared to polyacrylic acid (PAA), and longer EO chains further reduced oil–water interfacial tension. Emulsification tests verified its strong ability to emulsify crude oil. Sandpack flooding experiments and micromodel studies demonstrated effective conformance control and high displacement efficiency, achieving up to 30.65% incremental oil recovery. These findings offered essential insights for designing hydrophobic associative polymers with tunable interfacial properties for EOR applications. Full article

Single-column hybrid-reinforced self-centering segmental assembled bridges (SHR-SCSAB) exhibit vertical stiffness discontinuities, significantly impacting the refinement of their seismic design methodology. In this study, we investigate SHR-SCSAB by employing the finite strip method to calculate the maximum transverse bearing capability of segmental assembled piers, and the corresponding horizontal displacement at the pier top. By leveraging the mechanical properties of hybrid reinforcement materials, we further derive an analytical expression for the equivalent elastic stiffness of SHR-SCSAB as an integrated system. OpenSees software was used to establish a finite element model of the SHR-SCSAB, and the agreement between numerical simulations and analytical solutions validates the accuracy of the derived equivalent elastic stiffness expression. Additionally, this study evaluates the seismic performance of single-column SHR-SCSAB and examines the influence of key parameters on its behavior. The results demonstrate that hybrid reinforcement effectively addresses the low energy dissipation capacity inherent in self-centering bridges while preserving their advantage of minimal residual displacement. These findings significantly advance the refinement of seismic design methods for SHR-SCSAB. Full article

Double-column self-centering segmentally assembled bridges (SC-SABs) present greater design complexity compared to single-column systems, primarily due to vertical stiffness discontinuities at segmental spandrel abutments, which critically affect the refinement of their seismic design methods. To address these challenges, this study conducts a systematic investigation into the mechanical behavior and seismic performance of double-column SC-SAB. First, leveraging fundamental mechanical principles and stress-strain relationships, the coupling mechanism between the two columns is analytically established. An analytical expression for the elastic stiffness of a double-column SC-SAB, when simplified to an equivalent single-column system, is derived. This establishes the equivalent stiffness conditions for reducing a double-column system to a single-column model, and the overall equivalent stiffness of the double-column system is formulated. To validate the theoretical framework, a finite element model of the double-column SC-SAB is developed using OpenSees (1.0.0.1 version). An equivalent single-column model is constructed based on the derived stiffness equivalence conditions. By comparing the peak displacement and bearing capacity between the double-column and equivalent single-column models, the accuracy and feasibility of the simplification approach are confirmed. The numerical results further validate the derived overall equivalent stiffness, providing a robust theoretical foundation for simplified engineering applications. Additionally, pushover analysis and hysteretic response analysis are performed to systematically evaluate the influence of key design parameters on the seismic performance of double-column SC-SAB. The results demonstrate that the prestressed twin-column system exhibits excellent self-centering capability, effectively controlling residual displacements, aligning with seismic resilience goals. This research advances the seismic design methodology for SC-SAB by resolving critical challenges in stiffness equivalence and joint behavior quantification. The findings of this study can be utilized to derive equivalent damping ratios and equivalent periods. Based on the displacement response spectrum, the pier-top displacement and maximum force can be determined, thereby enabling a displacement-based seismic design approach. This research holds significant theoretical and practical value for advancing seismic design methodologies for self-centering segmental bridge piers and enhancing the seismic safety of bridge structures. Full article

In this study, we explore the design of novel random poly(lauryl methacrylate-co-tert-butyl methacrylate-co-methacrylic acid), P(LMA-co-tBMA-co-MAA) copolymers via the RAFT copolymerization of LMA and tBMA followed by the selective hydrolysis of tBMA segments. For the molecular characterization of the novel copolymer, a series of physicochemical techniques were implemented, including size exclusion chromatography (SEC), proton nuclear magnetic resonance (¹H-NMR) and attenuated total reflectance–Fourier transform infrared (ATR–FTIR) spectroscopy. Our experimental results confirmed the successful synthesis of the targeted copolymers. The compositions were in accordance with the targeted differing fraction of hydrophobic tBMA/LMA elements, and hydrolysis resulted in at least 64% conversion to hydrophilic MAA units. The copolymers, bearing both an amphiphilic character and polyelectrolyte properties while being composed of randomly distributed monomeric segments of biocompatible materials, were subsequently investigated in terms of their self-assembly behavior in aqueous solutions. Dynamic light scattering and fluorescence spectroscopy experiments demonstrated the formation of self-assembled nanoaggregates (average hydrodynamic radii, R_h < 100 nm) that formed spontaneously, having low critical aggregation concentration (CAC) values (below 3.5 × 10⁻⁶ g/mL), and highlighted the feasibility of using these copolymer systems as nanocarriers for biomedical applications. Full article

Self-assembling amphiphilic polymers represent highly promising materials with emerging applications across various fields. In these polymers, the presence of hydrophilic and hydrophobic segments within their structure drives the self-assembly process in aqueous environments, leading to organized structures capable of incorporating lipophilic drugs. Their high chemical versatility enables the design of tailored structures to meet specific requirements, such as the active targeting ability, thereby broadening their potential applications. In this work, a polyethylene glycol-phospholipid conjugate was employed to form nanocarriers loaded with a lipophilic derivative of gemcitabine. To achieve nano-assemblies actively targeted towards cancer cells overexpressing the hyaluronic acid (HA) receptor CD44, a HA-phospholipid conjugate was co-formulated in various molar ratios (1%, 10%, and 20%). All formulations exhibited a mean diameter below 130 nm, a negative zeta potential (approximately −30 mV), and a high encapsulation efficiency (above 90%). These nano-assemblies demonstrated stability during storage and effectively released the encapsulated drug in a cell culture medium. Upon incubation with cancer cells, the nano-assemblies were internalized via a CD44 endocytosis-mediated mechanism, with the extent of internalization depending on the HA conjugate content. Consistently, cell viability studies revealed that the nanocarriers decorated with higher amounts of HA exerted a higher cytotoxicity, enabling a fine tuning of the nano-assembly properties. Full article

Background/Objectives: Paclitaxel (PTX) is a potent anticancer drug that is poorly soluble in water. To enhance its delivery efficiency in aqueous environments, amphiphilic polymer micelles are often used as nanocarriers for PTX in clinical settings. However, the hydrophilic polymer segments on the surface of these micelles may possess potential immunogenicity, posing risks in clinical applications. To address this issue, nanomicelles based on human serum albumin (HSA)–hydrophobic polymer conjugates constructed via site-specific in situ polymerization-induced self-assembly (SI-PISA) are considered a promising alternative. The HSA shell not only ensures good biocompatibility but also enhances cellular uptake because of endogenous albumin trafficking pathways. Moreover, compared to traditional methods of creating protein–hydrophobic polymer conjugates, SI-PISA demonstrates higher reaction efficiency and better preservation of protein functionality. Methods: We synthesized HSA-PMEMA nanomicelles via SI-PISA using HSA and methoxyethyl methacrylate (MEMA)—a novel hydrophobic monomer with a well-defined and stable chemical structure. The protein activity and the PTX intracellular delivery efficiency of HSA-PMEMA nanomicelles were evaluated. Results: The CD spectra of HSA and HSA-PMEMA exhibited similar shapes, and the relative esterase-like activity of HSA-PMEMA was 94% that of unmodified HSA. Flow cytometry results showed that Cy7 fluorescence intensity in cells treated with HSA-PMEMA-Cy7 was approximately 1.35 times that in cells treated with HSA-Cy7; meanwhile, HPLC results indicated that, under the same conditions, the PTX loading per unit protein mass on HSA-PMEMA was approximately 1.43 times that of HSA. These collectively contributed to a 1.78-fold overall PTX intracellular delivery efficiency of HSA-PMEMA compared to that of HSA. Conclusions: In comparison with HSA, HSA-PMEMA nanomicelles exhibit improved cellular uptake and higher loading efficiency for PTX, effectively promoting the intracellular delivery of PTX. Tremendous potential lies in these micelles for developing safer and more efficient next-generation PTX formulations for tumor treatment. Full article

Three-dimensional genome organization reveals that gene regulatory elements, which are linearly distant on the genome, can spatially interact with target genes to regulate their expression. DNA fluorescence in situ hybridization (DNA-FISH) is an efficient method for studying the spatial proximity of genomic loci. In this study, we developed an optimized Tn5 transposome-based DNA-FISH method, termed Tn5-labeled DNA-FISH. This approach amplifies the target region and uses a self-assembled Tn5 transposome to simultaneously fragment the DNA into ~100 bp segments and label it with fluorescent oligonucleotides in a single step. This method enables the preparation of probes for regions as small as 4 kb and visualizes both endogenous and exogenous genomic loci at kb resolution. Tn5-labeled DNA-FISH provides a streamlined and cost-effective tool for probe generation, facilitating the investigation of chromatin spatial conformations, gene interactions, and genome architecture. Full article

Highly symmetric protein cages represent one of the most artistic architectures formed by biomolecules. However, the underlying reasons for the formation of some of these architectures remain unknown. The present study aims to investigate the significance behind their morphological formation by fabricating protein cage-like vesicles using a synthetic polymer. The vesicles were synthesized by combining polymerization-induced self-assembly (PISA) with polymerization-induced microphase separation (PIMS), employing an amphiphilic poly(methacrylic acid)-block-poly(n-butyl methacrylate-random-cyclohexyl methacrylate-random-methacrylic acid) diblock copolymer, PMAA-b-P(BMA-r-CMA-r-MAA). The copolymer, with a 60 mol% molar ratio of CMA to the BMA units, produced clathrin-like vesicles with angular windows in their shell, resulting from the segregation of the hard CMA units from the soft BMA matrix in the hydrophobic phase of the vesicle. These vesicles were highly stable against rising temperatures. In contrast, the vesicles with a 30 mol% CMA ratio dissociated upon heating to 50 °C into triskelion-like segments due to intramolecular microphase separation. These findings indicate that designing synthetic polymers can mimic living organ morphologies, aiding in elucidating their morphological significance and inspiring the development of new materials utilizing these morphologies. Full article

There is relatively little research on cyclic amphiphilic block polymers, having both hydrophilic and hydrophobic segments placed in the ring and thus resulting in a higher degree of topological restriction, as drug vehicles. Cyclic amphiphilic binary block polymer is synthesized by the click coupling reaction of bimolecular homodifunctional precursors. The results indicate that cyclization between linear polymer precursors is successful if the trace linear by-products generated are ignored, which also suggests that the small molecule bifunctional terminating agent applied in traditional bimolecular homodifunctional ring-closure process can be extended to large molecule. Moreover, the study on the self-assembly behavior of polymers shows that, compared with linear counterparts, the stability and drug loading capacity of micelles based on the resultant cyclic polymer are not significantly improved due to the influence of topological structure and linear impurities. Nevertheless, drug loaded micelles formed by the obtained cyclic polymers still exhibit superior cellular uptake ability. It can be seen that topological effects do play an irreplaceable role in the application performance of polymers. Therefore, the construction and synthesis of cyclic and its derivative polymers with moderate topological confinement and high purity may be a key direction for future exploration of polymer drug delivery carriers. Full article

The development of new convenient tools for the design of multicomponent nucleic acid (NA) complexes is one of the challenges in biomedicine and NA nanotechnology. In this paper, we analyzed the formation of hybrid RNA/DNA concatemers and self-limited complexes by a pair of oligonucleotides using UV melting, circular dichroism spectroscopy, and a gel shift assay. Effects of the size of the linker between duplex-forming segments of the oligonucleotides on complexes’ shape and number of subunits were compared and systematized for RNA/DNA, DNA/DNA, and RNA/RNA assemblies. The data on complex types summarized here as heat maps offer a convenient tool for the design of NA constructs. General rules found for RNA/DNA, DNA/DNA, and RNA/RNA complexes allow not only designing complexes with desired structures but also purposefully transforming their geometry. The A-form of the double helix of the studied RNA/DNA complexes was confirmed by circular dichroism analysis. Moreover, we show for the first time efficient degradation of RNA in hybrid self-limited complexes by RNase H and imidazole. The results open up new prospects for the design of supramolecular complexes as tools for nanotechnology, nanomachinery, and biomedical applications. Full article

Double hydrophilic, random, hyperbranched copolymers were synthesized via reversible addition–fragmentation chain transfer (RAFT) polymerization of oligo(ethylene glycol) methyl ether methacrylate (OEGMA) and 2-(dimethylamino)ethyl methacrylate (DMAEMA) utilizing ethylene glycol dimethacrylate (EGDMA) as the branching agent. The resulting copolymers were characterized in terms of their molecular weight and dispersity using size exclusion chromatography (SEC), and their chemical structure was confirmed using FT-IR and ¹H-NMR spectroscopy techniques. The choice of the two hydrophilic blocks and the design of the macromolecular structure allowed the formation of self-assembled nanoparticles, partially due to the pH-responsive character of the DMAEMA segments and their interaction with -COOH end groups remaining from the chain transfer agent. The copolymers showed pH-responsive properties, mainly due to the protonation–deprotonation equilibria of the DMAEMA segments. Subsequently, a nanoscopic polymer–lipid (lipomer) mixed system was formulated by complexing the synthesized copolymers with cosmetic amphiphilic emulsifiers, specifically glyceryl stearate (GS) and glyceryl stearate citrate (GSC). This study aims to show that developing lipid–polymer hybrid nanoparticles can effectively address the limitations of both liposomes and polymeric nanoparticles. The effects of varying the ionic strength and pH on stimuli-sensitive polymeric and mixed polymer–lipid nanostructures were thoroughly investigated. To achieve this, the structural properties of the hybrid nanoparticles were comprehensively characterized using physicochemical techniques providing insights into their size distribution and stability. Full article