Search Results (2,532)

Fretting wear due to flow-induced vibration (FIV) remains a primary cause of fuel failure in light water nuclear reactors. In the study of axial FIV, i.e., FIV caused by axial flows, three vibration characteristics, namely natural frequency, damping ratio, and root-mean-square (RMS) amplitude, are critical for mitigating fretting wear by avoiding resonance, maximising overdamping, and preventing large-amplitude instability motion, respectively. This paper presents a set of best practices for simulating axial FIV with a focus on predicting these parameters based on a URANS-FSI numerical framework, utilising high-Reynolds-number Unsteady Reynolds-Averaged Navier–Stokes (URANS) turbulence modelling and two-way fluid–structure interaction (FSI) coupling. This strategy enables accurate and efficient prediction of vibration parameters and offers promising scalability for full-scale nuclear fuel assembly applications. Validation is performed against a semi-empirical model to predict RMS amplitude and experimental benchmarking. The validation experiments involve two setups: vibration of a square beam with fixed and roller-supported ends in annular flow tested at Vattenfall AB, and self-excited vibration of a cantilever beam in annular flow tested at the University of Manchester. The study recommends best practices for numerical schemes, mesh strategies, and convergence criteria, tailored to improve the accuracy and efficiency for each validated parameter. Full article

Starch complexes have recently been identified as a new dietary supplement for dietary intervention in glycemic metabolism disorders. However, although the amylopectin significantly influenced starch complexes’ anti-digestibility, the underlying regulatory pattern remains unclear. Accordingly, this study constructed nano white waxy maize amylopectin (WMA) ternary complexes with a high self-assembly index (SI, 82.58%) using an ultrasound-assisted approach. And the relationship between self-assembly behavior and slow digestibility was revealed. Combined analyses of chemometrics revealed that during the WMA ternary self-assembly process, the increasing free side chains and α-1,6 glycosidic linkages contributed to the rise in potential, thereby generating more assembly sites and binding energy and ultimately elevating SI. Then, along with the transition from a diffuse state to V_h-type crystallinity and spherical configuration, increases in relative crystallinity, double helices, molecular weight, short-range order, and gel-network viscous were observed, whereas semicrystalline lamellar thickness and “blocklet” size decreased. These indicated that both the number and dimensions of hydrolysis channels were reduced. Consequently, the increasing gelatinization temperature led to rising slowly digestible starch content (19.86–43.28%), causing a more stable glycemic release after WMA ternary self-assembly. This investigation provides a key theoretical and technological foundation for the development of novel slow-digesting precision nutrition ingredients. Full article

Utilization of natural processes can reduce the complexity and production cost of any device by limiting the necessary steps in the production scheme, especially when it comes to fibers with periodic changes in refractive index. One such process is the nematic–isotropic phase separation of liquid crystal-based composite confined in 1D space. In this paper, we analyze the behavior of polymer-stabilized liquid crystal-based self-assembled periodic structures in an external electric field. We performed a detailed analysis regarding the reorientation of liquid crystal molecules under two orthogonal directions of the external electric field applied to the examined sample. It was demonstrated that the period of the polymerized structure remains constant until full reorientation, as the electric field induces the formation of new periodic defects in LC orientation. Consequently, the structure’s effective birefringence changes quite drastically, and this observed change depends on the direction of the electric field vector. The obtained results seem promising when it comes to application of the proposed periodic structures as voltage or electric field sensors operating as long-period fiber gratings or fiber Bragg gratings for the visible or near-infrared spectral regions. Full article

Background: Kenaf (Hibiscus cannabinus L.) is an important fiber crop belonging to the genus Hibiscus in the Malvaceae family. Research on its chloroplast genome holds significant importance for deciphering the evolutionary relationships of the Hibiscus species, developing genetic markers, and promoting kenaf (H. cannabinus) genetic breeding. Methods: Based on high-throughput sequencing technology, this study completed the sequencing and assembly of the kenaf (H. cannabinus) chloroplast genome. Results: (1) The kenaf (H. cannabinus) chloroplast genome exhibits a typical circular quadripartite structure with a total length of 163,019 bp, including a large single-copy region (LSC) of 90,467 bp, a small single-copy region (SSC) of 19,486 bp, and a pair of inverted repeat regions (IRa/IRb) of 26,533 bp each. The total GC content is 36.62%, among which, the IR region has the highest GC content (42.61%) and the SSC region the lowest (30.87%). (2) A total of 131 genes were annotated, including 85 mRNAs, 37 tRNAs, 8 rRNAs, and 1 pseudogene. Their functions cover photosynthesis (e.g., pet and atp family genes), self-replication (e.g., rpl, rps, and rpo family genes), and genes with unknown functions (e.g., ycf1 and ycf2). A codon usage bias analysis revealed that the relative synonymous codon usage (RSCU) value of the stop codon UAA is the highest (1.6329), and codons ending with A/U are preferentially used (e.g., GCU for alanine with RSCU = 1.778). (3) A repeat sequence analysis identified various interspersed repeat sequences (predominantly 30~31 bp in length, with a relatively high proportion in the 30~40 bp range, including forward and palindromic types) and simple sequence repeats (cpSSRs). Among them, single-base repeat SSRs account for the highest proportion (e.g., (A)8 and (T)9), and specific SSR primers were designed. (4) A comparative evolutionary analysis indicated that the Ka/Ks ratios (nonsynonymous substitution rate/synonymous substitution rate) of core chloroplast genes (e.g., rps2 and rpoC2) in kenaf (H. cannabinus) are all less than 1 (0.145~0.415), suggesting that they are under purifying selection. The collinearity similarity of chloroplast genomes between kenaf (H. cannabinus) and its closely related species reaches over 99.97%, and the IR region boundaries are relatively conserved. The phylogenetic tree shows that kenaf (H. cannabinus) clusters with closely related Hibiscus species with a 100% bootstrap value, indicating a close genetic relationship. Conclusions: This study provides basic data for the functional analysis of the kenaf (H. cannabinus) chloroplast genome, the phylogeny of Hibiscus, and the utilization of genetic resources. Full article

The prebiological anomeric selectivity of ribonucleosides is a key phenomenon in the understanding of the RNA world hypothesis and the origin of life. While each ribonucleoside can have two anomers (α or β), ribonucleosides naturally occur in the β form, while α anomers are extremely rare. Guanosine, a canonical ribonucleoside, binds to borate and self-assembles into G4-quartets, enabling the formation of borate–guanosine hydrogels. These macrostructures, exhibiting elevated thermal robustness and self-healing properties, have been suggested as plausible frameworks for the syntheses of prebiological molecules. Moreover, their external layers could have prevented degradation of compounds by aggressive primitive radiation and reduced molecular dispersion. Herein it is proposed that anomeric selectivity may have occurred due to the different 3D organization and stereochemical environment formed by each borate–guanosine anomer and subsequent formation of borate–guanosine hydrogels. DFT was applied to the optimization of α and β anomeric structures in four steps, from borate–guanosine diesters to G4 structures. The results obtained suggest that β-syn-guanosine (the most stable structure) is the only anomer that forms a planar G4-quartet with borate, capable of self-assembling into a hydrogel. Given the properties of borate–guanosine hydrogels, this could explain why β-guanosine is currently the sole anomer present in living organisms. Full article

Autophagy is a highly conserved catabolic process in eukaryotic cells that maintains cellular homeostasis by degrading damaged or superfluous intracellular components. Autophagy plays a dual, paradoxical role during viral infection. However, for most viruses, the induction of autophagy provides a favorable intracellular environment for the full completion of their life cycles. Most viruses that benefit from autophagy adopt a “regulate but not destroy” strategy, i.e., they initiate the autophagic process while suppressing their immune system through mechanisms such as blocking autophagosome-lysosome fusion. This allows them to avoid self-elimination while redirecting other functions of the autophagic machinery—for instance, utilizing autophagy-derived structures such as autophagosomes and double-membrane vesicles (DMVs) as specialized sites for viral genome replication, particle assembly, and maturation. The maintenance of cellular homeostasis by autophagy is crucial for the establishment of viral infection, as it provides a viable cellular microenvironment for viral replication; after infection occurs, inhibiting the degradative function of autophagy becomes a key strategy for viruses. Although canonical degradative autophagy exerts a negative effect on most viruses, redirected nondegradative autophagic structures and repurposed autophagic mechanisms are essential for the efficient replication of various viruses. In-depth analysis of this dynamic virus-autophagy interplay will provide important insights for elucidating virus-host interactions and developing autophagy-targeted antiviral strategies. Full article

Carbon aerogels (CAs) had been well applied in extreme condition thermal insulation, but achieving a balance between mechanical robustness and thermal insulation remains challenging. We present a novel strategy to fabricate carbon aerogels with tunable mechanical properties and thermal insulation properties by tailoring their skeleton architecture via molecular assembly. Carbon precursor aerogel with thick neck particle packing structure was obtained by strong hydrogen-bonding-induced self-assembly between polyurethane-urea oligomer (PUU) and phenolic resin (PF), and carbon aerogel retained robust interparticle connections after pyrolysis, resulting in excellent mechanical properties. The presence of PUU leads to denser packing of resin molecules, promotes graphitization of the carbon and formation of nanocrystalline structures at 1400 °C, resulting in optimized compression modulus and strength. The closed pore structure of carbon skeleton was further studied by Small-Angle X-ray Scattering (SAXS), while moderate pore width (0.4–0.6 nm) optimizes the balance between strength (110 MPa) and thermal conductivity (0.30 W/(m·K)). This work demonstrates that molecular-level assembly combined with pyrolysis control enables precise tuning of carbon aerogel structures and properties, providing new insights for high-temperature thermal insulation applications. Full article

Tungsten oxide (WO₃) nanostructures have emerged as promising electroactive materials due to their high pseudocapacitance, structural versatility, and chemical stability, while reduced graphene oxide (rGO) provides excellent electrical conductivity and surface area. The strategic combination of these nanomaterials in hybrid electrodes has gained attention for enhancing the energy storage performance of supercapacitors. In this work, we report the fabrication and electrochemical performance of nanostructured multilayer films based on the electrostatic Layer-by-Layer (LbL) self-assembly of poly (amidoamine) (PAMAM) dendrimers alternated with tungsten oxide (WO₃) nanofibers dispersed in reduced graphene oxide (rGO). The films were deposited onto indium tin oxide (ITO) substrates and subsequently subjected to electrochemical reduction. UV-Vis spectroscopy confirmed the linear growth of the multilayers, while atomic force microscopy (AFM) revealed homogeneous surface morphology and thickness control. Electrochemical characterization by cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) revealed a predominantly electrical double-layer capacitive (EDLC) behavior. From the GCD measurements (PAMAM/rGO-WO₃)₂₀ films achieved an areal capacitance of ≈2.20 mF·cm⁻², delivering an areal energy density of ≈0.17 µWh·cm⁻² and an areal power density of ≈2.10 µW·cm⁻², demonstrating efficient charge storage in an ultrathin electrode architecture. These results show that the synergistic integration of PAMAM dendrimers, reduced graphene oxide, and WO₃ nanofibers yields a promising strategy for designing high-performance electrode materials for next-generation supercapacitors. Full article

Four benzyltrimethylammonium (BTMA) salts were successfully prepared: bis(benzyltrimethylammonium) hexachloroplatinate (1), benzyltrimethylammonium tetrachloroaurate (2), bis(benzyltrimethylammonium) tetrachlorocuprate (3), and bis(benzyltrimethylammonium) tetrabromocuprate (4) from benzyltrimethylammonium hydroxide (Triton B). Their crystal structures were determined by single-crystal X-ray diffraction, and the supramolecular architectures were characterized hierarchically. Extended Hirshfeld surface analysis, including enrichment ratio calculations, was performed to evaluate intermolecular interactions. Nonclassical hydrogen bonds, such as C–H^…Cl(Br), involving the anions, contribute to the formation of self-assembled architectures. Additional stabilization arises from π^…π and Cu–Br^…π interactions, particularly in crystals 2 and 4, respectively. Hirshfeld surface analysis showed that H^…H and C^…H/H^…C interactions are the dominant contributors in all crystals. According to enrichment ratio calculations, C^…H/H^…C interactions in 1, 3, and 4; Cl^…H/H^…Cl in 1 and 3; Cu^…H/H^…Cu in 3 and 4; and Br^…H/H^…Br and Br^…C/C^…Br in 4 are statistically favored in the crystal packing. Halogen bonding Cl^…Cl was observed in 1 but does not significantly influence packing. Energy framework calculations indicated that dispersive interactions are favorable in the analyzed crystals. A library of H-bonding supramolecular patterns, including interchangeable synthons, is provided and may guide the rational design of new derivatives with controllable features. Finally, the topology of intermolecular connections and the electronic structure of the benzyltrimethylammonium cation, investigated by quantum-chemical calculations, provide insights into its reactivity. Full article

Silk proteins are versatile biopolymers well-suited to act as foundational components of a wide range of biomaterials. Rapidly gelling, self-assembling systems are especially valuable for drug delivery and biomedical applications. In this study, we present a way to induce the solid coaggregation of silk fibroin (SF) by adding the anionic surfactant sodium dodecylbenzene sulfonate (SDBS) into an SF solution prepared in formic acid (FA). SF films prepared by dissolving silk in CaCl₂–FA and subsequently rinsing in water to remove CaCl₂ were re-solubilized in FA with different content of SDBS. It was found that SF aggregation time is strongly modulated by the presence of SDBS. At increasing surfactant content, hydrophobic interactions between the SF chains and SDBS promote the formation of spherical coaggregates, whose size increases with surfactant concentration. FTIR analysis reveals that this process is accompanied by the formation of β-sheet structures, likely driven by hydrophobic interactions. This spontaneous liquid-to-solid phase transition promotes the formation of mechanically robust SF films with tunable electrical properties. Full article

The synthesis of biocidal peptide materials using simple, low-cost, solvent-free methods is a crucial challenge for developing new antimicrobial approaches. In this study, we produced proteinoid nanostructures through simple, inexpensive, and environmentally friendly thermal reactions between glutamic acid (Glu) and tyrosine (Tyr) in various molar ratios. Mechanistically, the thermal cyclization of glutamic acid into pyroglutamic acid (pGlu) facilitated the formation of short peptide chains containing pGlu as the N-terminus moiety and subsequent L-tyrosine or glutamic acid residues, which self-assembled into nanometric spheroidal structures that exhibit blue emission. Spectroscopic (FTIR, UV-Vis, photoluminescence) and mass (LC-MS) analyses confirmed the formation of mixed pGlu-/Tyr/Glu peptides. All products exhibit dose-dependent antimicrobial activity against Methicillin-Resistant Staphylococcus aureus (MRSA), with a minimum inhibitory concentration (MIC) of 25 mg mL⁻¹ for the GluTyr 1:1 and 2:1 proteinoids. The outcomes observed following 24 h exposure of the HEK293 cell line to the materials indicate their suitability for integration into hybrid systems for antimicrobial surfaces. This work is the first to demonstrate a direct antibacterial activity of proteinoids obtained by thermal condensation, opening up the possibility of designing a new class of synthetic antimicrobial peptides. Full article

Since the introduction of the DNA origami technology by Seeman and Rothemund, the integration of functional entities (nanoparticles, quantum dots, antibodies, etc.) has been of huge interest to broaden the area of applications for this technology. The possibility of precise functionalization of the DNA origami technology gives opportunity to build up complex novel structures, opening up endless opportunities in medicine, nanotechnology, photonics and many more. The main advantage of the DNA origami technology, namely the self-assembly mechanism, can represent a challenge in the construction of complex mixed-material structures. Commonly, DNA origami structures are purified post-assembly by filtration (either spin columns or membranes) to wash away excess staple strands. However, this purification step can be critical since these functionalized DNA origami structures tend to agglomerate during purification. Therefore, custom production and purification procedures need to be applied to produce purified functionalized DNA origami structures. In this paper, we present a workflow to produce functionalized DNA origami structures, as well as a method to qualify the successful hybridization of a quantum dot to a square frame DNA origami structure. Through the utilization of a FRET fluorophore–quencher pair as well as a subsequent assembly, successful hybridization can be performed and confirmed using photoluminescence measurements. Full article

Background/Objectives: A carrier-free self-assembled nanomedicine delivery system refers to a high drug-loading nanomedicine delivery system prepared by one or more active drug ingredients through supramolecular self-assembly, which has the advantages of high drug-loading and a simple preparation process, enabling multidrug synergistic therapy. 10-hydroxycamptothecin (HCPT) have active antitumor effects. Pentacyclic triterpenes are natural active components with a wide range of pharmacological activities. This study aimed to investigate the impact of structural types on the self-assembly of pentacyclic triterpenes and HCPT. Methods: Molecular docking studies were performed. Self-assembled nanoparticles were designed by co-assembling ursolic acid (UA), asiatic acid (AA), oleanic acid (OA), and betulinic acid (BA) with HCPT via anti-solvent precipitation combined with ultrasonication, followed by characterization. Cytotoxicity assays using the CCK-8 method revealed that the prepared self-assembled nanoparticles exhibited concentration-dependent inhibitory effects against A375, AGS, HCT-116, and HepG2 tumor cells. Confocal laser scanning microscopy (CLSM) indicated that UA/HCPT nanoparticles (UA/HCPT-NPs) were more efficiently internalized and accumulated in cells compared with the UA + HCPT physical mixture. Results: Both in vitro and in vivo results demonstrated that the self-assembled nanoparticles significantly enhanced antitumor efficacy while exerting minimal toxicity on major organs within the tested dose range. Conclusions: In summary, these findings highlight that pentacyclic triterpenoids components possess significant self-assembly potential, and that dual-drug co-delivery via self-assembled nanoparticles represents as a promising strategy for cancer therapy. Full article

The formation of hemoglobin (Hb) and myoglobin (Mb) supramolecular complexes is examined. These key proteins for oxygen transport and storage undergo conformational transitions, some of which are induced by stress factors, particularly redox-active and toxic substances, e.g., reactive oxygen species (ROS) and reactive carbonyl compounds (RCC). These modifications can lead to partial denaturation, exposure of hydrophobic regions, and loss of stability, promoting self-assembly into high-molecular structures. Reversible associations serve regulatory roles: protein stabilization, transient functional inactivation, and generation of biological signals. Irreversible associations result in the formation of stable aggregates constituting pathological hallmarks of amyloidosis and other proteopathies. Although Hb and Mb fibrillization is not part of their physiological function, under oxidative stress, altered pH, high temperatures, or the presence of post-translational modifications, they can adopt amyloid-like structures characterized by cross-β conformation. Such aggregates exhibit high resistance to proteolysis and accumulate in tissues. Understanding molecular mechanisms behind Hb and Mb aggregation is critical for the diagnosis and timely therapy of amyloid-related diseases. The stability, regular structure, and biocompatibility of Hb and Mb fibrils make them promising for biomedical applications. Functional nanomaterials based on these fibrils are being developed for high-sensitivity biosensors, bioelectronic devices, and nanocarriers for targeted drug delivery. 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